JP7441012B2 - adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

In general, adhesives (also referred to as pressure-sensitive adhesives, hereinafter the same) exhibit a soft solid state (viscoelastic body) in a temperature range around room temperature, and have the property of easily adhering to an adherend under pressure. Taking advantage of these properties, adhesives are widely used in various fields in the form of adhesive sheets with a base material that have an adhesive layer on the base material, or in the form of base material-less adhesive sheets that do not have a base material. It's being used. As a technical document regarding adhesives, Patent Document 1 can be cited.

JP2013-216726A

Adhesives are required to have various properties depending on their use. Some of these characteristics are difficult to achieve at a high level, such as when trying to improve one characteristic, the other tends to deteriorate. An example of such characteristics that are difficult to coexist is adhesion to an adherend and reworkability. The above-mentioned rework is, for example, when an adhesive sheet fails to adhere to an adherend (misalignment, generation of wrinkles or air bubbles, foreign matter gets caught, etc.), or when an adhesive sheet is attached to an adherend after it has been applied. This refers to peeling off the adhesive sheet from the adherend and reapplying it if a defect is found. In particular, when the adherend is fragile or thin, the peeling force of the adhesive sheet from the adherend (i.e., the adhesive force to the adherend) should be kept low to prevent damage or deformation of the adherend due to rework. Therefore, it is not easy to realize a pressure-sensitive adhesive sheet that has good reworkability and can form a highly reliable bond.

Patent Document 1 discloses that the adhesive does not foam or peel off even when exposed to high temperature or high temperature and high humidity conditions, and that the adhesive remains on the adherend even if exposed to high temperature conditions after being applied to the adherend. It has been described that in order to achieve both the property of being able to be peeled off without causing adhesive residue (adhesive-retaining property), an organopolysiloxane having a specific structure and/or a hydrolyzed condensate thereof is contained in the pressure-sensitive adhesive composition. However, no adhesive residue and low peel strength are different properties. Patent Document 1 does not consider reducing the peeling force during rework in order to prevent damage to the adherend.

Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet that can be easily peeled off using an aqueous liquid such as water and that can form a highly reliable bond. Another object of the present invention is to provide a laminate constructed using the above pressure-sensitive adhesive sheet.

According to this specification, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer is provided. The adhesive layer has an adhesive surface that can be attached to an adherend. The above-mentioned pressure-sensitive adhesive sheet has a water peeling force FW0 of 1, which is measured at a pulling speed of 300 mm/min and a peeling angle of 180 degrees by supplying 20 μL of peeling water 3 hours after the adhesive surface is pasted on the alkali glass plate. .0N/10mm or less. The above-mentioned pressure-sensitive adhesive sheet was prepared by pasting the pressure-sensitive adhesive surface on an alkali glass plate and heat-treating it at 60°C for 5 hours, then supplying 20 μL of peeling water, pulling at a speed of 300 mm/min, and peeling at a peel angle of 180 degrees at room temperature. The water peeling force FW2 measured in is 4.0 N/10 mm or more. Since such a pressure-sensitive adhesive sheet has a low water peeling force FW0, it can be easily peeled off from an adherend using an aqueous liquid such as water. Moreover, since the above-mentioned pressure-sensitive adhesive sheet has a high water peeling force FW2, it can be bonded to an adherend with good water resistance and reliability.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed in this specification, after 7 days have elapsed since the pressure-sensitive adhesive surface has been pasted on an alkali glass plate at room temperature, 20 μL of release water is supplied, the tension speed is 300 mm/min, and the peel angle is 180. The water peeling force FW1 measured under the conditions of 1.0 N/10 mm or less is 1.0 N/10 mm or less. Since the above-mentioned pressure-sensitive adhesive sheet has a low water peeling force FW1 after 7 days at room temperature, it can be easily peeled off using an aqueous liquid such as water even after a certain period of time has passed after being attached to an adherend. Is possible. By this, it is possible to improve the productivity of the laminate produced by pasting the above-mentioned pressure-sensitive adhesive sheet to an adherend and the flexibility of process control.

The adhesive layer preferably contains a compound S having an alkoxysilyl group represented by the following general formula (A) and a hydrophobic part in the molecule as a peel force increasing agent.
-Si(CH ₃ ) _n (OR) _3-n (A)
(where n is 0 or 1 and R is selected from methyl and ethyl groups.)
Since Compound S has a hydrolyzable alkoxy group (-SiOR group), it exhibits an effect of improving peeling force at the interface between the adhesive surface and the adherend, and can contribute to improving bonding reliability. The pressure-sensitive adhesive sheet disclosed herein can be suitably produced using Compound S.

In some embodiments, the adhesive layer includes, as the compound S, a compound having an ethoxysilyl group. By using the compound S having an ethoxysilyl group, an early increase in water peeling force can be suppressed, and a pressure-sensitive adhesive sheet having a high water peeling force FW2 can be suitably realized.

In some embodiments, the adhesive layer includes, as the compound S, a compound having a molecular weight of 500 [g/mol] or more. By using such compound S, it is possible to suppress an early increase in water peeling force and to suitably realize a pressure-sensitive adhesive sheet having a high water peeling force FW2.

In the pressure-sensitive adhesive sheet according to some embodiments, the pressure-sensitive adhesive layer includes a water affinity agent. By containing a water affinity agent in the adhesive layer, the water releasability of the adhesive surface can be improved.

In the pressure-sensitive adhesive sheet according to some embodiments, the pressure-sensitive adhesive layer may be a layer formed from a photocurable or solvent-type pressure-sensitive adhesive composition. A pressure-sensitive adhesive layer formed from such a pressure-sensitive adhesive composition is suitable for realizing a pressure-sensitive adhesive sheet having a low water peeling force FW0 and a high water peeling force FW2. A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition described above is also preferable from the viewpoint of optical properties (eg, transparency) of the pressure-sensitive adhesive layer.

In some embodiments, the adhesive layer is a photocrosslinkable adhesive layer. The deformation resistance of the photo-crosslinkable adhesive layer can be improved by photo-crosslinking the photo-crosslinkable adhesive constituting the layer. As a result, according to an adhesive sheet having a photo-crosslinkable adhesive layer, for example, by photo-crosslinking the photo-crosslinkable adhesive layer after pasting the adhesive sheet on an adherend, the surface of the adhesive sheet is It is possible to form a bond with good shape followability and high deformation resistance after photo-crosslinking.

The adhesive sheet according to some embodiments has the adhesive surface attached to an alkali glass plate and held in a moist heat environment of 85°C and 85% RH for 24 hours, and then held in an environment of 23°C and 50% RH for 5 hours. The peel strength after moist heat FN1 is 3.0 N/10 mm or more, which is measured under the same environment at a tensile speed of 300 mm/min and a peel angle of 180 degrees after being maintained for a period of time. A pressure-sensitive adhesive sheet having a high peel strength FN1 after wet heat can form a bond with good wet heat durability.

According to this specification, a laminate including a member and an adhesive sheet layer laminated on the member is provided. The adhesive sheet layer is a layer formed by laminating any of the adhesive sheets disclosed herein to the member. As a result, the laminate can have the pressure-sensitive adhesive sheet layer and the member joined together with good reliability.

In some embodiments, the member has a contact angle with respect to distilled water of 50 degrees or less on the surface to which the pressure-sensitive adhesive sheet is bonded. The laminate disclosed herein can be preferably implemented in a mode including such a member.

Note that an appropriate combination of each of the above-mentioned elements may also be included within the scope of the invention for which protection by patent is sought by the present patent application.

FIG. 1 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to an embodiment. FIG. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment. FIG. 1 is a cross-sectional view schematically showing an optical member with an adhesive sheet attached to the optical member with an adhesive sheet according to an embodiment.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in this specification that are necessary for carrying out the present invention are based on the teachings regarding carrying out the invention described in this specification and the common general knowledge at the time of filing. can be understood by those skilled in the art. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the field. Furthermore, in the following drawings, members and portions that have the same function may be described with the same reference numerals, and overlapping descriptions may be omitted or simplified. Further, the embodiments shown in the drawings are schematic for clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actually provided products.

In this specification, the term "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of an acrylic monomer, and is also referred to as an acrylic polymer. The above-mentioned acrylic monomer refers to a monomer derived from a monomer having at least one (meth)acryloyl group in one molecule. Furthermore, in this specification, "(meth)acryloyl" refers comprehensively to acryloyl and methacryloyl. Similarly, "(meth)acrylate" comprehensively refers to acrylate and methacrylate, and "(meth)acrylic" comprehensively refers to acrylic and methacrylic.

<Example of configuration of adhesive sheet>
FIG. 1 shows an example of the configuration of the adhesive sheet disclosed herein. This adhesive sheet 1 is a one-sided adhesive including an adhesive layer 10 whose one surface 10A is a surface to be attached to an adherend, and a base material 20 laminated on the other surface 10B of the adhesive layer 10. It is constructed as a sticky adhesive sheet. The adhesive layer 10 is fixedly bonded to one surface 20A of the base material 20. As the base material 20, for example, a plastic film such as a polyester film can be used. In the example shown in FIG. 1, the adhesive layer 10 has a single-layer structure. The adhesive sheet 1 before use (before being attached to an adherend) is, for example, as shown in FIG. It may be in the form of an adhesive sheet 50 with a release liner, which is protected by a release liner. Alternatively, the second surface 20B (the surface opposite to the first surface 20A, also referred to as the back surface) of the base material 20 is a release surface, and the adhesive surface 10A is on the second surface 20B of the base material 20. The adhesive surface 10A may be protected by being wound or laminated so as to be in contact with each other.

The release liner is not particularly limited, and includes, for example, a release liner in which the surface of a liner base material such as a resin film or paper has been subjected to release treatment, a fluorine-based polymer (such as polytetrafluoroethylene), or a polyolefin-based resin (such as polyethylene, polypropylene, etc.). ) can be used, such as a release liner made of a low adhesive material. For example, a silicone-based, long-chain alkyl-based, or other release agent may be used for the above-mentioned peeling treatment. In some embodiments, a release-treated resin film may be preferably employed as the release liner.

The adhesive layer of the adhesive sheet disclosed herein is not limited to a single layer structure as in the above structural example, and in addition to the above adhesive layer (typically a compound S-containing adhesive layer), the adhesive layer may be the same or different. It may further include one or more adhesive layers (additional adhesive layers) having the same composition. Each of the one or more additionally arranged pressure-sensitive adhesive layers may or may not contain the above-mentioned compound S. When the additional adhesive layer is disposed closer to the base material than the above-mentioned adhesive layer, the additional adhesive layer may contain a peel force increasing agent (e.g. , compound S) may or may not be included.

The adhesive sheet disclosed herein may be in the form of a base material-less double-sided adhesive sheet consisting of an adhesive layer. As shown in FIG. 2, before use, the base material-less double-sided adhesive sheet 2 has a peelable surface in which each side 10A, 10B of the adhesive layer 10 has at least the adhesive layer side a releasable surface (release surface). It may be in a form protected by liners 31, 32. Alternatively, the back surface of the release liner 31 (the surface opposite to the adhesive side) is the release surface, and the adhesive surface 10B is wound or laminated so that the back surface of the release liner 31 comes into contact with the adhesive surface. 10A and 10B may be in a protected form. Such a base material-less double-sided pressure-sensitive adhesive sheet can be used, for example, by bonding a base material to either surface of the pressure-sensitive adhesive layer.

The adhesive sheet disclosed herein may be a component of a member with an adhesive sheet, in which a member (for example, an optical member) is bonded to one surface of the adhesive layer. For example, the adhesive sheet 1 shown in FIG. 1 may be a component of an optical member 100 with an adhesive sheet, in which an optical member 70 is joined to one surface 10A of the adhesive layer 10, as shown in FIG. The above-mentioned optical member preferably has a non-water-absorbing smooth surface on which the pressure-sensitive adhesive sheet is attached. The optical member with a pressure-sensitive adhesive sheet having such a configuration can be easily reworked by applying a water peeling method, which will be described later, if necessary, when the pressure-sensitive adhesive sheet is attached to the optical member. The optical member may be, for example, a glass substrate, a resin film, a metal plate, a resin film having a surface-modified layer containing glass (for example, a coating layer, a sputtered layer, etc.), or the like. Further, the surface of the member to be bonded to the adhesive sheet may be subjected to a hydrophilic treatment. Examples of the hydrophilic treatment include treatments that contribute to improving hydrophilicity (for example, introduction of hydroxyl groups), such as corona treatment, plasma treatment, and hydrophilic coating treatment that provides a hydrophilic coating layer.

<Characteristics of adhesive sheet>
(Water peeling force FW0)
The adhesive sheet disclosed herein preferably has a water peeling force FW0 (hereinafter also referred to as "initial water peeling force") of 1.0 N/10 mm or less.
The above water peeling force FW0 was measured 3 hours after pasting the adhesive surface of the adhesive sheet to be measured on an adherend, supplying 20 μL of peeling water, pulling at a pulling speed of 300 mm/min, and at a peeling angle of 180 degrees. Ru. The pressure-sensitive adhesive sheet having the water peeling force FW0 can be easily peeled off from the adherend using an aqueous liquid such as water after being attached to the adherend. Thereby, for example, if a problem such as foreign matter getting caught or poor adhesion is observed during application to an adherend, the adhesive sheet can be easily peeled off from the adherend and reapplied.
In some embodiments, the water peel force FW0 (initial water peel force) is preferably less than 1.0 N/mm, may be less than 0.8 N/10 mm, may be less than 0.7 N/10 mm, and may be less than 0.7 N/10 mm. It may be less than 6N/10mm. With a pressure-sensitive adhesive sheet having a lower water peeling force FW0, it is possible to further reduce the load applied to an adherend when the pressure-sensitive adhesive sheet is peeled off by a water peeling method. This applies, for example, to adhesives that are attached to thin adherends, fragile adherends, adherends that are easily deformed (elongated, warped, twisted, etc.), adherends that have a thin film on the surface that is easily damaged, etc. This is particularly significant in sheets. The lower limit of the water peeling force FW0 is not particularly limited, and may be substantially 0 N/10 mm, may be more than 0 N/10 mm, or may be 0.1 N/10 mm or more.

In addition, from the viewpoint of improving reworkability, in the measurement of the water peeling force FW0, a pressure-sensitive adhesive sheet that can be peeled off from an adherend without leaving any adhesive on the adherend is preferable. That is, a pressure-sensitive adhesive sheet with excellent adhesive-free properties is preferable. Whether or not the adhesive remains on the adherend can be determined, for example, by visually observing the adherend after peeling off the adhesive sheet. Similarly, in the measurement of water peeling forces FW1 to FW3 described below, a pressure-sensitive adhesive sheet that can be peeled off from an adherend without leaving any adhesive on the adherend is preferred.

The pressure-sensitive adhesive sheet disclosed herein can improve bonding reliability (for example, water resistance reliability) by increasing water peeling force at a desired timing. The above-mentioned increase in water peeling force can be promoted by performing appropriate heat treatment. The heating temperature when performing the above heat treatment can be, for example, 40°C or higher, 50°C or higher, or 60°C or higher. The upper limit of the heating temperature is not particularly limited. Usually, it is appropriate to set the heating temperature to 100°C or lower, preferably 80°C or lower, 65°C or lower, or 45°C or lower. The heating time when performing the above-mentioned heat treatment can be set so as to appropriately obtain the effect of promoting an increase in water peeling force, and is not particularly limited. The heating time can be selected from a range of about 5 minutes to 12 hours, for example.

(Water peeling force FW2)
The pressure-sensitive adhesive sheet disclosed herein preferably has a water peeling force FW2 (hereinafter also referred to as "water peeling force after heat treatment") of 4.0 N/10 mm or more.
The above-mentioned water peeling force FW2 is determined by applying 20 μL of peeling water after pasting the adhesive side of the adhesive sheet to be measured on an adherend and heat-treating it at 60°C for 5 hours at a tensile speed of 300 mm/min and a peeling angle of 180 mm. Measured at room temperature under 30°C conditions. According to the pressure-sensitive adhesive sheet having a high water peeling force FW2, a bond with good water resistance and reliability can be formed after the water peeling force increases.
In some embodiments, the water peeling force FW2 (water peeling force after heat treatment) is preferably 4.5 N/10 mm or more, and may be 5.0 N/10 mm or more from the viewpoint of water resistance reliability. It may be 0N/10mm or more, or it may be 7.0N/10mm or more. The upper limit of the water peeling force FW2 is not particularly limited. In some embodiments, the water peeling force FW2 may be, for example, 20 N/10 mm or less, may be 15 N/10 mm or less, and may be 10 N/10 mm or less, from the viewpoint of facilitating both suppression of the water peeling force FW1 described below. The following may be used.

Note that the pressure-sensitive adhesive sheet disclosed in this specification includes embodiments in which there is no restriction on water peeling force, and in such embodiments, the pressure-sensitive adhesive sheet is not limited to one that satisfies the above-mentioned water peeling forces FW0 and FW2. Moreover, the above-mentioned heat treatment is not an essential treatment for increasing the water peeling force of the pressure-sensitive adhesive sheet disclosed herein. For example, by keeping it in a temperature range around room temperature for a long period of time (for example, about 30 days or more) after pasting it on the adherend, the water peeling force against the adherend can be increased and the reliability of water resistance can be increased. It is possible. After a process or period in which it is desired to have good water release properties (low water release force) on the adherend, heat treatment can be performed at an appropriate timing as necessary to increase the water release force. can be promoted.

(Water peeling force FW1)
The adhesive sheet disclosed herein preferably has a water peeling force FW1 (hereinafter also referred to as "water peeling force after 7 days at room temperature") of 1.0 N/10 mm or less.
The above-mentioned water peeling force FW1 was determined under the conditions of applying 20 μL of peeling water after pasting the adhesive surface of the adhesive sheet to be measured on an adherend at room temperature for 7 days, pulling at a pulling speed of 300 mm/min, and peeling angle of 180 degrees. It is measured in More specifically, it is measured by the procedure described in the Examples described later. A pressure-sensitive adhesive sheet with a low water peeling force FW1 can be easily peeled off using an aqueous liquid such as water even after 7 days have passed at room temperature since application. According to such a pressure-sensitive adhesive sheet, for example, it is possible to perform rework work on laminates manufactured within a predetermined period (for example, within 7 days) at once. This can improve productivity and flexibility in process control of a laminate produced by pasting the pressure-sensitive adhesive sheet onto an adherend (for example, a member, preferably an optical member).
In some embodiments, the water peeling force FW1 (water peeling force after 7 days at room temperature) is preferably less than 1.0 N/mm, may be less than 0.8 N/10 mm, and may be less than 0.7 N/10 mm. , may be less than 0.6N/10mm. According to an adhesive sheet with a low water peeling force FW1, even after a certain period of time has passed after pasting on the adherend, the load applied to the adherend when the adhesive sheet is peeled off by the water peeling method is reduced. It can be reduced. This applies, for example, to adhesives that are attached to thin adherends, fragile adherends, adherends that are easily deformed (elongated, warped, twisted, etc.), adherends that have a thin film on the surface that is easily damaged, etc. This is particularly significant in sheets. The lower limit of the water peeling force FW1 is not particularly limited, and may be substantially 0 N/10 mm, may be more than 0 N/10 mm, or may be 0.1 N/10 mm or more.

(Water peeling force FW3)
The adhesive sheet according to some preferred embodiments preferably has a water peel force FW3 (hereinafter also referred to as "water peel force after 14 days at room temperature") of 1.0 N/10 mm or less. According to such a pressure-sensitive adhesive sheet, it is possible to further improve the productivity and flexibility of process control of a laminate produced by pasting the pressure-sensitive adhesive sheet onto an adherend. The above-mentioned water peeling force FW3 is measured after 14 days have elapsed at room temperature after pasting the adhesive surface to the adherend, supplying 20 μL of peeling water, pulling speed 300 mm/min, and peeling angle 180 degrees. More specifically, it is measured by the procedure described in the Examples described later. The water peeling force FW3 (water peeling force after 14 days at room temperature) is preferably less than 1.0 N/mm, may be less than 0.8 N/10 mm, may be less than 0.7 N/10 mm, and may be less than 0.6 N/10 mm. It may be less than The lower limit of the water peeling force FW2 is not particularly limited, and may be substantially 0 N/10 mm, more than 0 N/10 mm, or 0.1 N/10 mm or more.

(Peel strength after moist heat FN1)
In some embodiments of the adhesive sheet disclosed herein, the adhesive sheet preferably has a peel strength FN1 after moist heat of 3.0 N/10 mm or more.
The above peel strength after moist heat FN1 is determined by pasting the adhesive side of the adhesive sheet to be measured on an adherend and holding it in a moist heat environment of 85°C and 85% RH for 24 hours, then under an environment of 23°C and 50% RH. After holding the sample for 5 hours, it is measured under the same environment at a tensile rate of 300 mm/min and a peeling angle of 180 degrees (no water is used). More specifically, it is measured by the procedure described in the Examples described later. A pressure-sensitive adhesive sheet having a high peel strength FN1 after moist heat is preferable from the viewpoint of bonding reliability.
The wet heat peel strength FN1 is more preferably 5.0 N/10 mm or more, may be 7.0 N/10 mm or more, may be 10 N/10 mm or more, or may be 12 N/10 mm or more. The upper limit of the wet heat peel strength FN1 is not particularly limited. In some embodiments, the water peeling force FW2 may be, for example, 25 N/10 mm or less, 20 N/10 mm or less, or even 15 N/10 mm or less, from the viewpoint of facilitating the suppression of the water peeling force FW1. good.

In measuring the water peeling forces FW1 to FW3 and the peel strength after moist heat FN1, an alkali glass plate having a contact angle of 5 degrees to 10 degrees with respect to distilled water is used as the adherend. As such an alkali glass plate, an alkali glass plate manufactured by Matsunami Glass Industry Co., Ltd. (thickness 1.35 mm, blue plate edge polished product) is used. Alternatively, a product equivalent to the above-mentioned alkali glass plate manufactured by Matsunami Glass Industry Co., Ltd. can be used. As the tensile testing machine, a universal tensile compression testing machine (device name: "Tensile Compression Testing Machine, TCM-1kNB", manufactured by Minebea) or its equivalent can be used. The peel strength is measured so that the test piece attached to the adherend is peeled off from the bottom to the top. A similar measuring method is used in the examples described later.
In addition, in the case of a pressure-sensitive adhesive sheet including a photo-crosslinkable pressure-sensitive adhesive layer, in which a part or all of the pressure-sensitive adhesive layer is photo-crosslinked after being bonded to the adherend, After being attached to the alkali glass plate, the test piece is irradiated with light through the alkali glass plate in an environment of 23° C. and 50% RH. When the object to be measured is a double-sided adhesive sheet, the measurement can be performed by attaching a PET film to one adhesive surface of the double-sided adhesive sheet for lining as described below.

The contact angle of the alkali glass plate is measured as follows. That is, in a measurement atmosphere of 23°C and 50% RH, a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name "Model DMo-501", a control box "DMC-2", and a control/analysis software "FAMAS") was used. Measurements are performed by the droplet method using version 5.0.30). The amount of distilled water dropped is 2 μL, and the contact angle is calculated from the image 5 seconds after dropping by the Θ/2 method (implemented with N5).

(Haze value)
In the technology disclosed herein, the haze value of the adhesive sheet is suitably about 10% or less, and may be about 5% or less (for example, about 3% or less). The haze value is preferably 1.0% or less. Adhesive sheets with such high transparency are suitable for optical applications that require high light transmittance. The haze value of the adhesive sheet may be less than 1.0%, may be less than 0.7%, and may be 0.5% or less (for example, 0 to 0.5%). These haze values regarding the adhesive sheet can also be preferably applied to the haze value of the adhesive layer in the technology disclosed herein.

Here, the "haze value" refers to the ratio of diffusely transmitted light to the total transmitted light when visible light is irradiated onto the measurement target. Also called cloudiness value. The haze value can be expressed by the following formula.
Th[%]=Td/Tt×100
In the above formula, Th is the haze value [%], Td is the scattered light transmittance, and Tt is the total light transmittance.
The haze value can be measured using a haze meter (for example, "MR-100" manufactured by Murakami Color Research Institute). The haze value can be adjusted, for example, by selecting the composition, thickness, etc. of the adhesive layer.

<Adhesive layer>
The adhesive layer of the adhesive sheet disclosed herein includes, for example, an acrylic adhesive, a rubber adhesive (natural rubber type, synthetic rubber type, a mixture thereof, etc.), a silicone adhesive, a polyester adhesive, An adhesive layer comprising one or more adhesives selected from various known adhesives such as urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. could be. Here, the acrylic adhesive refers to an adhesive whose base polymer is an acrylic polymer. The same meaning applies to rubber adhesives and other adhesives. Note that the concept of polymers herein also includes polymers with a relatively low degree of polymerization, which are generally referred to as oligomers. In this specification, the "base polymer" of the adhesive refers to the main component of the polymer contained in the adhesive. Furthermore, in this specification, the term "main component" refers to a component contained in an amount exceeding 50% by weight, unless otherwise specified.

(acrylic adhesive)
From the viewpoint of transparency, weather resistance, etc., in some embodiments, an acrylic pressure-sensitive adhesive can be preferably employed as a constituent material of the pressure-sensitive adhesive layer. The acrylic pressure-sensitive adhesive may be made of, for example, a monomer component containing 40% by weight or more of a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms at the ester end. Preferably, the base polymer contains an acrylic polymer having the following structure. Hereinafter, a (meth)acrylic acid alkyl ester having an alkyl group having at least X and Y or less carbon atoms at the ester end may be referred to as "(meth)acrylic acid C _XY alkyl ester." Since it is easy to balance the properties, it is appropriate that the proportion of (meth)acrylic acid C _1-20 alkyl ester in the total monomer components of the acrylic polymer according to one embodiment is more than 50% by weight, For example, it may be 55% by weight or more, 60% by weight or more, or 70% by weight or more. For the same reason, the proportion of (meth)acrylic acid C _1-20 alkyl ester in the monomer components may be, for example, 99.9% by weight or less, 99.5% by weight or less, or even 99% by weight or less. good. The proportion of the C _1-20 (meth)acrylic acid alkyl ester in the entire monomer component of the acrylic polymer according to another embodiment may be, for example, 98% by weight or less, from the viewpoint of improving the cohesiveness of the adhesive layer. It may be 95% by weight or less, 85% by weight or less (for example, less than 80% by weight), 70% by weight or less, or 60% by weight or less.

Non-limiting specific examples of (meth)acrylic acid C _1-20 alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, ( n-butyl meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, (meth) Hexyl acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, (meth)acrylate ) Decyl acrylate, Isodecyl (meth)acrylate, Undecyl (meth)acrylate, Dodecyl (meth)acrylate, Tridecyl (meth)acrylate, Tetradecyl (meth)acrylate, Pentadecyl (meth)acrylate, (Meth) Examples include hexadecyl acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

Among these, it is preferable to use at least C _4-20 alkyl (meth)acrylate, and more preferably to use at least C _4-18 alkyl (meth)acrylate. For example, it is preferable that the monomer component contains one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA), and an acrylic pressure-sensitive adhesive containing at least 2EHA is particularly preferable. Other examples of (meth)acrylic acid C _4-20 alkyl esters that may be preferably used include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA). ) etc.

In some embodiments, the monomer component constituting the acrylic polymer may contain 40% by weight or more of (meth)acrylic acid C _4-18 alkyl ester. The proportion of (meth)acrylic acid C _4-18 alkyl ester in the monomer components may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. It may be a monomer component containing (meth)acrylic acid C _6-18 alkyl ester in a proportion equal to or higher than any of the lower limits mentioned above.
In addition, from the viewpoint of improving the cohesiveness of the adhesive layer, it is appropriate that the proportion of (meth)acrylic acid C _4-18 alkyl ester in the monomer components is usually 99.5% by weight or less, and 95% by weight. % or less, 85% by weight or less, or 75% by weight or less. It may also be a monomer component containing (meth)acrylic acid C _6-18 alkyl ester in a proportion below any of the above-mentioned upper limits.

The monomer components constituting the acrylic polymer include (meth)acrylic acid alkyl ester and, if necessary, other monomers (copolymerizable monomers) that can be copolymerized with (meth)acrylic acid alkyl ester. You can stay there. As the copolymerizable monomer, monomers having a polar group (e.g., carboxyl group, hydroxyl group, nitrogen atom-containing ring, etc.) and monomers with a relatively high homopolymer glass transition temperature (e.g., 10° C. or higher) are preferably used. can do. A monomer having a polar group can be useful for introducing crosslinking points into the acrylic polymer and increasing the cohesive force of the adhesive. The copolymerizable monomers can be used alone or in combination of two or more.

Specific non-limiting examples of copolymerizable monomers include the following.
Carboxy group-containing monomers: for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.
Acid anhydride group-containing monomers: for example, maleic anhydride, itaconic anhydride.
Hydroxyl group-containing monomer: For example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth)acrylate 4-hydroxybutyl acid, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxy) Hydroxyalkyl (meth)acrylates such as methylcyclohexyl)methyl (meth)acrylate, etc.
Monomers containing sulfonic or phosphoric acid groups: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfonate Propyl (meth)acrylate, (meth)acryloyloxynaphthalene sulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc.
Epoxy group-containing monomers: For example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl (meth)acrylate, allyl glycidyl ether, glycidyl (meth)acrylate, and the like.
Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc.
Isocyanate group-containing monomers: for example, 2-(meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc.
Amide group-containing monomer: For example, (meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth) N,N-dialkyl (meth)acrylamide such as acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide; N-ethyl(meth)acrylamide , N-alkyl (meth)acrylamides such as N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, and Nn-butyl (meth)acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; Monomers having a hydroxyl group and an amide group, such as N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth) N-hydroxyalkyl (meth)acrylamide such as acrylamide; monomers having an alkoxy group and an amide group, such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide N-alkoxyalkyl (meth)acrylamide such as; others such as N,N-dimethylaminopropyl (meth)acrylamide, N-(meth)acryloylmorpholine, etc.
Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate.
Monomers having epoxy groups: for example glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3 -Morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinyl Thiazole, N-vinylisothiazole, N-vinylpyridazine, etc. (eg, lactams such as N-vinyl-2-caprolactam).
Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyhexamethylene succinimide, etc.
Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.
Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl itaconimide etc.
Aminoalkyl (meth)acrylates: For example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, (meth)acrylic acid t -Butylaminoethyl.
Alkoxy group-containing monomers: For example, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, (meth)acrylic acid Alkoxyalkyl (meth)acrylates (alkoxyalkyl (meth)acrylates) such as butoxyethyl, ethoxypropyl (meth)acrylate; methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, (meth)acrylate; Alkoxyalkylene glycol (meth)acrylates (eg, alkoxypolyalkylene glycol (meth)acrylates) such as methoxypolypropylene glycol acrylate.
Alkoxysilyl group-containing monomers: For example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxy Alkoxysilyl group-containing (meth)acrylates such as propylmethyldiethoxysilane, alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane, etc.
Vinyl esters: for example, vinyl acetate, vinyl propionate, etc.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene, etc.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene, etc.
(Meth)acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, etc. (meth)acrylate containing an alicyclic hydrocarbon group.
(Meth)acrylic acid ester having an aromatic hydrocarbon group: For example, an aromatic hydrocarbon group-containing (meth)acrylate such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.
In addition, heterocycle-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, and silicon atom-containing such as silicone (meth)acrylates. (Meth)acrylate, (meth)acrylic acid ester obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use it in an amount of 0.01% by weight or more based on the total monomer components. In order to better exhibit the effects of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more, or 0.5% by weight or more based on the total monomer components. In addition, from the viewpoint of making it easier to balance the adhesive properties, the amount of the copolymerizable monomer to be used is usually appropriate to be 50% by weight or less, preferably 40% by weight or less, based on the total monomer components.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use it in an amount of 0.01% by weight or more based on the total monomer components. In order to better exhibit the effects of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more, or 0.5% by weight or more based on the total monomer components. In addition, from the viewpoint of making it easier to balance the adhesive properties, the amount of the copolymerizable monomer to be used is usually appropriate to be 50% by weight or less, preferably 40% by weight or less, based on the total monomer components.

で表わされるＮ－ビニル環状アミドが挙げられる。ここで、一般式（１）中、Ｒ¹は２価の有機基であり、具体的には－（ＣＨ２₂）_ｎ－である。ｎは２～７（好ましくは２，３または４）の整数である。なかでも、Ｎ－ビニル－２－ピロリドンを好ましく採用し得る。窒素原子を有するモノマーの他の好適例としては、（メタ）アクリルアミドが挙げられる。 In some embodiments, the monomer component constituting the acrylic polymer may include a monomer having a nitrogen atom. Thereby, the cohesive force of the adhesive can be increased, and the peeling force after aging can be preferably improved. A preferred example of the monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used, for example, general formula (1):

N-vinyl cyclic amide represented by: Here, in the general formula (1), R ¹ is a divalent organic group, specifically -(CH2 ₂ ) _n -. n is an integer from 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably employed. Another suitable example of a monomer having a nitrogen atom is (meth)acrylamide.

When using a monomer having a nitrogen atom (preferably a monomer having a nitrogen atom-containing ring such as N-vinyl cyclic amide), the amount used is not particularly limited, and is, for example, 1% by weight or more of the total monomer components. The content may be 2% by weight or more, 3% by weight or more, further 5% by weight or more, or 7% by weight or more. In one embodiment, the amount of the nitrogen atom-containing monomer used may be 10% by weight or more, 15% by weight or more, or 20% by weight or more of the total monomer components. Further, the amount of the monomer having a nitrogen atom to be used is preferably, for example, 40% by weight or less of the entire monomer component, may be 35% by weight or less, may be 30% by weight or less, and may be 25% by weight or less. Good too. In another aspect, the amount of the nitrogen atom-containing monomer used may be, for example, 20% by weight or less, or 15% by weight or less of the total monomer components.

In some embodiments, the monomer component constituting the acrylic polymer may include a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force and degree of crosslinking (for example, crosslinking using an isocyanate crosslinking agent) of the adhesive can be suitably adjusted. The amount used when using a hydroxyl group-containing monomer is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, 0.5% by weight or more of the entire monomer component, It may be 1% by weight or more, 5% by weight or more, or 10% by weight or more. In addition, from the viewpoint of suppressing water absorption in the adhesive layer, in some embodiments, the amount of the hydroxyl group-containing monomer used is, for example, 40% by weight or less of the entire monomer component, and even if it is 30% by weight or less. The content may be 25% by weight or less, or 20% by weight or less. In another embodiment, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the entire monomer component.

In the adhesive layer of the adhesive sheet disclosed herein, the monomer component of the acrylic polymer may or may not contain the alkoxyalkyl (meth)acrylate or alkoxypolyalkylene glycol (meth)acrylate exemplified above. good. In one aspect of the technology disclosed herein, the proportion of alkoxyalkyl (meth)acrylate among the monomer components of the acrylic polymer is less than 20% by weight, and the proportion of alkoxypolyalkylene glycol (meth)acrylate is less than 20% by weight. less than %. Thereby, the adhesive layer can be easily formed into a sheet without problems such as gelation. The proportion of alkoxyalkyl (meth)acrylate in the monomer component is preferably less than 10% by weight, more preferably less than 3% by weight, even more preferably less than 1% by weight, and in a particularly preferred embodiment, the monomer component Substantially free of alkoxyalkyl (meth)acrylate (content 0 to 0.3% by weight). Similarly, the proportion of alkoxypolyalkylene glycol (meth)acrylate in the monomer components is preferably less than 10% by weight, more preferably less than 3% by weight, even more preferably less than 1% by weight, and in one particularly preferred embodiment , the monomer component is substantially free of alkoxypolyalkylene glycol (meth)acrylate (content 0 to 0.3% by weight).

In some embodiments, the proportion of the carboxy group-containing monomer in the monomer components of the acrylic polymer may be, for example, 2% by weight or less, 1% by weight or less, and 0.5% by weight or less (for example, 0.5% by weight or less). (less than 1% by weight). It is not necessary to substantially use a carboxy group-containing monomer as a monomer component of the acrylic polymer. Here, "substantially not using a carboxy group-containing monomer" means not using a carboxy group-containing monomer at least intentionally. An acrylic polymer having such a composition tends to have high reliability in water resistance, and can also have metal corrosion prevention properties for adherends containing metal.

Furthermore, in a preferred embodiment, the proportion of hydrophilic monomers in the monomer components of the acrylic polymer is limited. Thereby, the water releasability due to the water affinity agent described below is preferably exhibited. Here, the "hydrophilic monomer" in this specification refers to a carboxy group-containing monomer, an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, a monomer having a nitrogen atom (typically, an amide group-containing monomer such as (meth)acrylamide) monomers, monomers having a nitrogen atom-containing ring such as N-vinyl-2-pyrrolidone) and alkoxy group-containing monomers (typically alkoxyalkyl (meth)acrylates and alkoxypolyalkylene glycol (meth)acrylates) do. In this embodiment, the proportion of the hydrophilic monomer in the monomer components of the acrylic polymer is preferably 35% by weight or less, for example, it may be 30% by weight or less, or even 28% by weight or less. good. Although not particularly limited, the proportion of the hydrophilic monomer in the monomer components of the acrylic polymer may be 1% by weight or more, 10% by weight or more, or 20% by weight or more. It may be.

In some embodiments, the monomer component constituting the acrylic polymer may include an alicyclic hydrocarbon group-containing (meth)acrylate. Thereby, the cohesive force of the adhesive can be increased, and the peeling force after aging can be improved. As the alicyclic hydrocarbon group-containing (meth)acrylate, those exemplified above can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably employed. When using the alicyclic hydrocarbon group-containing (meth)acrylate, the amount used is not particularly limited, and can be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more based on the total monomer components. In one embodiment, the amount of the alicyclic hydrocarbon group-containing (meth)acrylate used may be 10% by weight or more, or 15% by weight or more of the entire monomer component. The upper limit of the amount of alicyclic hydrocarbon group-containing (meth)acrylate used is approximately 40% by weight or less, for example, it may be 30% by weight or less, and it may be 25% by weight or less (for example, 15% by weight or less). % or less, or even 10% by weight or less).

The composition of the monomer components constituting the acrylic polymer can be set so that the glass transition temperature Tg determined by the Fox equation based on the composition of the monomer components is, for example, −75° C. or higher and 10° C. or lower. In some embodiments, the above Tg is suitably 0°C or less, preferably -10°C or less, and preferably -20°C or less, from the viewpoint of the surface shape followability of the adhesive layer. The temperature may be -30°C or lower. Further, from the viewpoint of cohesiveness of the adhesive layer, the Tg may be, for example, -60°C or higher, -50°C or higher, -45°C or higher, or -40°C or higher.

Here, the above Fox equation is a relational equation between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below. .
1/Tg=Σ(Wi/Tgi)
In the above Fox equation, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi is the weight fraction of monomer i in the copolymer. Represents the glass transition temperature (unit: K) of a homopolymer.

As the glass transition temperature of the homopolymer used to calculate Tg, the value described in a known document shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomers.
2-Ethylhexyl acrylate -70℃
n-butyl acrylate -55℃
Isostearyl acrylate -18℃
Methyl methacrylate 105℃
Methyl acrylate 8℃
Cyclohexyl acrylate 15℃
N-vinyl-2-pyrrolidone 54℃
2-Hydroxyethyl acrylate -15℃
4-Hydroxybutyl acrylate -40℃
Dicyclopentanyl methacrylate 175℃
Isobornyl acrylate 94℃
Acrylic acid 106℃
Methacrylic acid 228℃

Regarding the glass transition temperature of homopolymers of monomers other than those exemplified above, the values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. If multiple types of values are listed in this document, the highest value is adopted. For monomers whose homopolymer glass transition temperature is not described in the Polymer Handbook, the value obtained by the method described in JP-A No. 2007-51271 shall be used.

The acrylic polymer disclosed herein is not particularly limited, but preferably has an SP value of 23.0 (MJ/m ³ ) ^1/2 or less. By incorporating a water affinity agent described below into an adhesive containing an acrylic polymer having such an SP value, an adhesive with a low initial water peeling force (FW0) and a high water peeling force after heating (FW2) can be obtained. The agent can be preferably realized. The SP value is more preferably 21.0 (MJ/m ³ ) ^1/2 or less (for example, 20.0 (MJ/m ³ ) ^1/2 or less). The lower limit of the above SP value is not particularly limited, and for example, it is suitably about 10.0 (MJ/m ³ ) ^1/2 or more, or about 15.0 (MJ/m ³ ) ^1/2 or more. It is preferably 18.0 (MJ/m ³ ) ^1/2 or more.

The SP value of acrylic polymers is calculated according to the calculation method of Fedors ["Polymer Engineering and Science (POLYMER ENG. &SCI.)", Vol. 14, No. 2 (1974), pp. 148-154] Reference] That is, the formula:
SP value δ=(Σ△e/Σ△v) ^1/2
(In the above formula, Δe is the evaporation energy Δe of each atom or atomic group at 25°C, and Δv is the molar volume of each atom or atomic group at the same temperature.);
It can be calculated according to The acrylic polymer having the above SP value can be obtained by appropriately determining the monomer composition based on the common technical knowledge of those skilled in the art.

The adhesive layer of the adhesive sheet disclosed herein contains monomer components having the composition as described above in the form of a polymerized product, an unpolymerized product (that is, a form in which the polymerizable functional group is unreacted), or a mixture thereof. The layer may be formed from a pressure-sensitive adhesive composition comprising: The above adhesive compositions include water-dispersed adhesive compositions in which the adhesive (adhesive component) is dispersed in water, solvent-based adhesive compositions in which the adhesive is contained in an organic solvent, and UV and radiation resistant adhesive compositions. An active energy ray-curable adhesive composition prepared to be cured by active energy rays to form an adhesive, and a hot melt adhesive composition that is applied in a heated molten state and forms an adhesive when cooled to around room temperature. It can be in various forms such as a composition. The pressure-sensitive adhesive composition according to one preferred embodiment is a solvent-type pressure-sensitive adhesive composition or a solvent-free pressure-sensitive adhesive composition. Solvent-free adhesive compositions include active energy ray-curable adhesive compositions and hot-melt adhesive compositions.

In the polymerization, a known or conventional thermal polymerization initiator or photopolymerization initiator may be used depending on the polymerization method, polymerization mode, etc. Such polymerization initiators can be used alone or in an appropriate combination of two or more.

The thermal polymerization initiator is not particularly limited, but includes, for example, an azo polymerization initiator, a peroxide initiator, a redox initiator based on a combination of a peroxide and a reducing agent, and a substituted ethane initiator. etc. can be used. More specifically, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-amidinopropane) ) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutyramidine), 2 , 2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate; persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide, t-butyl Peroxide-based initiators such as hydroperoxide and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; e.g. combinations of persulfates and sodium bisulfite, combinations of peroxides and sodium ascorbate Examples include, but are not limited to, redox initiators such as; Note that thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100°C (typically 40 to 80°C).

The photopolymerization initiator is not particularly limited, but includes, for example, a ketal photopolymerization initiator, an acetophenone photopolymerization initiator, a benzoin ether photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, and an α- Ketol-based photoinitiators, aromatic sulfonyl chloride-based photoinitiators, photoactive oxime-based photoinitiators, benzoin-based photoinitiators, benzyl-based photoinitiators, benzophenone-based photoinitiators, alkylphenone-based photoinitiators A photopolymerization initiator, a thioxanthone photopolymerization initiator, etc. can be used.

The amount of such a thermal polymerization initiator or photopolymerization initiator to be used can be a normal amount depending on the polymerization method, polymerization mode, etc., and is not particularly limited. For example, approximately 0.001 to 5 parts by weight (typically approximately 0.01 to 2 parts by weight, for example approximately 0.01 to 1 part by weight) of a polymerization initiator may be used for 100 parts by weight of the monomer to be polymerized. I can do it.

In the above polymerization, various conventionally known chain transfer agents (which may also be understood as molecular weight regulators or polymerization degree regulators) can be used as necessary. As the chain transfer agent, mercaptans such as n-dodecylmercaptan, t-dodecylmercaptan, thioglycolic acid, and α-thioglycerol can be used. Alternatively, a chain transfer agent that does not contain sulfur atoms (non-sulfur chain transfer agent) may be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; α-methylstyrene and α-methylstyrene dimer. Styrenes such as dibenzylidene acetone, cinnamyl alcohol, and cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; 2,3-dimethyl-2-butene , olefins such as 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like.
One type of chain transfer agent can be used alone or two or more types can be used in combination. When a chain transfer agent is used, the amount used can be, for example, approximately 0.01 to 1 part by weight per 100 parts by weight of the monomer component. The technology disclosed herein can also be preferably practiced in an embodiment that does not use a chain transfer agent.

The molecular weight of the acrylic polymer obtained by appropriately employing the various polymerization methods described above is not particularly limited, and can be set within an appropriate range depending on the required performance. The weight average molecular weight (Mw) of the acrylic polymer is usually about 10 x 10 ⁴ or more (for example, 20 x 10 ⁴ or more), and from the viewpoint of achieving both cohesive force and adhesive force in a well-balanced manner, it is 30 x 10 ⁴ It is appropriate to set it as super. The acrylic polymer according to one embodiment is preferably 40×10 ⁴ or more (typically about 50×10 ⁴ or more, for example about 55×10 ⁴ above). The upper limit of Mw of the acrylic polymer may usually be about 500×10 ⁴ or less (for example, about 150×10 ⁴ or less). The Mw may be approximately 75×10 ⁴ or less. Here, Mw refers to a standard polystyrene equivalent value obtained by gel permeation chromatography (GPC). As the GPC device, for example, a model name "HLC-8320GPC" (column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) may be used. The same applies to the embodiments described later. The above Mw may be the Mw of the acrylic polymer in either the adhesive composition or the adhesive layer.

Adhesive sheets according to some embodiments have an adhesive layer formed from an active energy ray-curable adhesive composition. As used herein, "active energy rays" refer to energy rays with energy capable of causing chemical reactions such as polymerization reactions, crosslinking reactions, and decomposition of initiators. Examples of active energy rays herein include light such as ultraviolet rays, visible rays, and infrared rays, and radiation such as α rays, β rays, γ rays, electron rays, neutron rays, and X rays. A preferred example of the active energy ray-curable adhesive composition is a photocurable adhesive composition. A photocurable pressure-sensitive adhesive composition has the advantage that even a thick pressure-sensitive adhesive layer can be easily formed. Among these, UV-curable pressure-sensitive adhesive compositions are preferred.

A photocurable pressure-sensitive adhesive composition typically contains at least a portion of the monomer components of the composition (which may be a portion of the type of monomer or a portion of the amount). Contains in the form of polymers. The polymerization method used to form the above-mentioned polymer is not particularly limited, and various conventionally known polymerization methods can be appropriately employed. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator); photopolymerization carried out by irradiating light such as ultraviolet rays (typically carried out in the presence of a thermal polymerization initiator); (Carried out in the presence of a photopolymerization initiator); Radiation polymerization carried out by irradiation with radiation such as β rays and γ rays; etc. can be employed as appropriate. Among these, photopolymerization is preferred.

A photocurable pressure-sensitive adhesive composition according to a preferred embodiment includes a partial polymer of monomer components. Such a partially polymerized product is typically a mixture of a polymer derived from a monomer component and an unreacted monomer, and preferably takes the form of a syrup (viscous liquid). Hereinafter, a partially polymerized product having such properties may be referred to as "monomer syrup" or simply "syrup." The polymerization method for partially polymerizing the monomer components is not particularly limited, and various polymerization methods such as those described above can be appropriately selected and used. From the viewpoint of efficiency and convenience, a photopolymerization method can be preferably employed. According to photopolymerization, the polymerization conversion rate (monomer conversion) of monomer components can be easily controlled by controlling the polymerization conditions such as the amount of light irradiation (light amount).

The polymerization conversion rate of the monomer mixture in the above partially polymerized product is not particularly limited. The polymerization conversion rate can be, for example, about 70% by weight or less, and preferably about 60% by weight or less. From the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition containing the above-mentioned partially polymerized product, the above-mentioned polymerization conversion rate is usually suitably about 50% by weight or less, and about 40% by weight or less (for example, about 35% by weight or less). % by weight or less) is preferred. The lower limit of the polymerization conversion rate is not particularly limited, but is typically about 1% by weight or more, and usually about 5% by weight or more is appropriate.

A pressure-sensitive adhesive composition containing a partial polymerization product of a monomer component can be obtained by, for example, partially polymerizing a monomer mixture containing the entire amount of the monomer component used for preparing the pressure-sensitive adhesive composition using an appropriate polymerization method (e.g., photopolymerization method). It can be obtained by In addition, an adhesive composition containing a partial polymer of a monomer component is a mixture of a partial polymer or a complete polymer of a monomer mixture containing a part of the monomer components used for preparing the adhesive composition, and the remaining monomer. It may be a mixture of the components or a partial polymer thereof. In this specification, the term "completely polymerized product" means that the polymerization conversion rate is more than 95% by weight.

The pressure-sensitive adhesive composition containing the above partially polymerized product may contain other components used as necessary (for example, a photopolymerization initiator, a peel force increasing agent as described below, a water affinity agent, a crosslinking agent, a polyfunctional monomers, acrylic oligomers, tackifying resins, etc.) may be blended. The method of blending such other components is not particularly limited, and for example, they may be included in the monomer mixture in advance, or may be added to the partially polymerized product.

Adhesive sheets according to some embodiments have an adhesive layer formed from a solvent-based adhesive composition. A solvent-based adhesive composition typically contains a solution polymer of monomer components and additives used as necessary. The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds (typically aromatic hydrocarbons) such as toluene; esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; 1,2- Selected from halogenated alkanes such as dichloroethane; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc. Any one type of solvent or a mixed solvent of two or more types can be used. According to solution polymerization, a polymerization reaction solution is obtained in which a polymer of monomer components is dissolved in a polymerization solvent. The solvent-based adhesive composition disclosed herein can be preferably manufactured using the above polymerization reaction solution.

The above-mentioned solvent-based adhesive composition may contain other components used as necessary (for example, a photopolymerization initiator, a peel force increasing agent as described below, a water affinity agent, a crosslinking agent, a polyfunctional monomer, an acrylic oligomers, etc.) may be blended. The solvent-based pressure-sensitive adhesive composition may be imparted with photocrosslinkability, for example, by adding a polyfunctional monomer and a photopolymerization initiator to the polymerization reaction solution.

(Peeling force increasing agent)
The adhesive layer of the adhesive sheet disclosed herein may contain a peel force increasing agent. As the peeling force increasing agent, a material capable of increasing the peeling force of the adhesive sheet from the adherend after the surface (adhesive surface) of the adhesive layer is attached to the adherend may be used as appropriate. It can be used selectively.

As the peel force increasing agent, for example, a compound S having an alkoxysilyl group and a hydrophobic part in the molecule may be used. An alkoxysilyl group is a functional group having at least one alkoxy group on a silicon atom. When the alkoxysilyl group is hydrolyzed, it generates a silanol group that reacts with the hydroxyl group on the surface of the adherend. Therefore, the alkoxysilyl group is a precursor of a group that reacts with the hydroxyl group. By containing the compound S in the adhesive layer, the peeling force of the adhesive sheet from the adherend can be increased by reaction or interaction between the hydroxyl groups on the adherend and the silanol groups. Furthermore, the hydrophobic portion of the compound S generally has a higher affinity with the base polymer (eg, acrylic polymer) of the adhesive layer than the alkoxysilyl group. By selecting this hydrophobic portion, it is possible to adjust the distribution and mobility of the compound S within the adhesive layer, and to control the increase in water peeling force.

The alkoxy group constituting the alkoxysilyl group is typically a methoxy group or an ethoxy group. The alkoxysilyl group may be a trialkoxysilyl group or a dialkoxysilyl group. From the viewpoint of enhancing the effect of increasing the peeling force, a compound S having a trialkoxysilyl group can be preferably employed in some embodiments. Compound S can be used alone or in combination of two or more.

In some embodiments, as the above-mentioned peeling force increasing agent, a compound S having an alkoxysilyl group represented by the following general formula (A) and a hydrophobic part in the molecule can be preferably used.
-Si(CH ₃ ) _n (OR) _3-n (A)
Here, n is 0 or 1 and R is selected from methyl and ethyl groups. For example, a compound S having an alkoxysilyl group in which n in the above general formula (A) is 0 may be preferably used.

The hydrophobic portion of the compound S may or may not have a reactive functional group (which may be a functional group that can react with the base polymer of the adhesive layer).
In one embodiment, a compound S (hereinafter sometimes referred to as compound S1) whose hydrophobic portion has at least one reactive functional group can be used. The number of reactive functional groups possessed by the hydrophobic portion of compound S1 may be, for example, about 1 to 5. From the viewpoint of suppressing gelation of the adhesive composition, etc., a compound S1 whose hydrophobic portion has one reactive functional group can be preferably employed. Examples of the above-mentioned reactive functional groups include epoxy groups, amino groups, isocyanate groups (which may constitute an isocyanurate group), acetoacetyl groups, (meth)acryloyl groups, mercapto groups, vinyl groups, and halogenated groups. Examples include alkyl groups. Various silane coupling agents can be used as the compound S1. Examples of the silane coupling agent having the above-mentioned reactive functional group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyltrimethoxysilane. Epoxy group-containing silane coupling agents such as oxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; for example, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3- Amino group-containing silane coupling agents such as aminopropyltrimethoxysilane and N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane; for example, 3-isocyanatepropyltriethoxysilane, tris(trimethoxysilylpropyl)isocyanurate, etc. isocyanate group-containing silane coupling agents; for example, acetoacetyl group-containing silane coupling agents such as acetoacetyl group-containing trimethoxysilane; for example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acrylic (meth)acryloyl group-containing silane coupling agents such as roxypropyltrimethoxysilane; vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxy Examples include mercapto group-containing silane coupling agents such as propyltrimethoxysilane; halogenated alkyl group-containing silane coupling agents such as 3-chloropropyltrimethoxysilane; and the like. Among these, epoxy group-containing silane coupling agents such as glycidoxypropyltrialkoxysilane (eg, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane) are preferred.

In another embodiment, a compound S (hereinafter sometimes referred to as compound S2) whose hydrophobic portion does not have a reactive functional group can be used. The hydrophobic part having no reactive functional group is, for example, a hydrocarbon group, a hydrocarbon group having a chain ether bond, a hydrocarbon group having a carbonyl group, a hydrocarbon group having an ester bond, a fluorinated product of these groups, etc. The hydrocarbon group in these examples can be an alkyl group, a cycloalkyl group, an aryl group, an alkylcycloalkyl group, an aralkyl group, and the like. When the hydrocarbon group is an alkyl group, the number of carbon atoms in the alkyl group is preferably 6 or more, more preferably 8 or more. The number of carbon atoms in the alkyl group may be, for example, 32 or less, 28 or less, 24 or less, or 20 or less. For example, C _8-18 alkyltrialkoxysilane can be used as compound S2. Non-limiting examples of _C8-18 alkyltrialkoxysilanes include octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, hexadecyltrimethoxysilane and hexadecyltriethoxysilane. Can be mentioned. Further, the number of carbon atoms in the cycloalkyl group, aryl group, alkylcycloalkyl group, and aralkyl group may be, for example, about 6 to 20. Note that the above-mentioned silane coupling agent is excluded from the concept of compound S (compound S2) having a structure in which the hydrophobic part does not have a reactive functional group.

The molecular weight [g/mol] of the compound S is not particularly limited, and may be, for example, about 120 to 30,000. For example, a compound S having a molecular weight of 180 or more, 200 or more, or 230 or more can be used. From the viewpoint of ease of controlling the reworkable period and mobility within the adhesive layer (particularly mobility to the adhesive surface), a compound S having a molecular weight of 240 or more (and even 260 or more) can be preferably used. . In some embodiments, a compound S having a molecular weight of 500 or more, 700 or more, 900 or more, 1200 or more, or 1500 or more can be preferably employed. In addition, from the viewpoints of ease of preparation and coating of the adhesive composition, mobility of compound S within the adhesive layer, etc., in some embodiments, the molecular weight is 20,000 or less, 10,000 or less, 7,000 or less, or 5,000 or less ( For example, Compound S having a molecular weight of 3,000 or less) can be preferably employed.
As the molecular weight of the compound S, the molecular weight (formula weight) based on the chemical formula or the weight average molecular weight based on the above GPC is adopted. When a commercially available product is used as Compound S, the nominal value provided by the manufacturer or the like may be used as the value of the molecular weight of the compound.

Compound S may have a hydrophobic portion having a repeating structure. For example, the hydrophobic portion of the compound S may be a polymer of an acrylic monomer that may or may not have a reactive functional group other than a (meth)acryloyl group. (Meth)acrylic acid alkyl esters are examples of acrylic monomers that do not have reactive functional groups other than (meth)acryloyl groups. The (meth)acrylic acid alkyl ester may be, for example, a (meth)acrylic acid C _1-20 alkyl ester, a (meth)acrylic acid C _1-18 alkyl ester, or a (meth)acrylic acid C _4-9 alkyl ester. It may be an alkyl ester or a (meth)acrylic acid C _6-9 alkyl ester. The above polymer of alkyl (meth)acrylate esters may be a homopolymer or a copolymer of two or more types of alkyl (meth)acrylate esters.

In the adhesive sheet disclosed herein, one suitable example of a material that can be preferably used as the compound S is a compound having an alkoxysilyl group and a hydrophobic part in the molecule (preferably represented by the above general formula (A)). compound) that satisfies one or both of the following: (1) the alkoxysilyl group is an ethoxysilyl group (e.g., triethoxysilyl group); and (2) the molecular weight is 500 [g/mol] or more. Compound S is mentioned. By using the compound S that corresponds to at least one of the above (1) and (2), it is possible to suppress an early increase in water peeling force and to suitably realize a pressure-sensitive adhesive sheet having a high water peeling force FW2. The reason for this is that the reaction between the hydroxyl group and the ethoxysilyl group on the surface of the adherend is clearly slower than the reaction with the methoxysilyl group, and/or that the compound S has a relatively large molecular weight, making it sticky. It is considered that the mobility within the adhesive layer is low and it takes time for the compound S present inside the adhesive layer to reach the adhesive surface and come into contact with the hydroxyl groups on the surface of the adherend. However, the interpretation shall not be limited to this reason alone.

The hydrophobic part of the compound S corresponding to (1) above may have a structure having a reactive functional group (compound S1) or may have a structure having no reactive functional group (compound S2). In some embodiments, a compound S having a reactive functional group (for example, an epoxy group) in the hydrophobic portion may be preferably employed from the viewpoint of wet heat durability and the like. For example, a compound S1 containing a hydrophobic part having an epoxy group as a reactive functional group (it may be a hydrophobic part having only an epoxy group as a reactive functional group) and a triethoxysilyl group can be used. ,
The molecular weight of the compound S corresponding to (1) above may be, for example, 10,000 or less, usually suitably 5,000 or less, 2,500 or less, or 1,500 or less. In some embodiments, the molecular weight of the compound S may be 800 or less, 500 or less, less than 500, 400 or less, or 340 or less, from the viewpoint of increasing the effect of increasing water release force by heat treatment. It may well be 310 or less. Further, from the viewpoint of suppressing early increase in water peeling force and non-staining of adherends, the above molecular weight may be, for example, 240 or more, 260 or more, or 270 or more.

The hydrophobic part of the compound S corresponding to (2) above may have a structure having a reactive functional group (compound S1) or may have a structure having no reactive functional group (compound S2). For example, a compound S2 containing a trimethoxysilyl group or an ethoxysilyl group and a hydrophobic portion having no reactive functional group can be used. The above-mentioned hydrophobic part having no reactive functional group may be, for example, a polymer of one or more monomers selected from acrylic monomers having no reactive functional group other than (meth)acryloyl group, or a hydrocarbon group. (For example, an alkyl group, a cycloalkyl group, an aryl group, an alkylcycloalkyl group, an aralkyl group), etc.

The peel force increasing agent is preferably contained in the adhesive layer in a free form. It is preferable that the peel force increasing agent is not chemically bonded to other components that may be included in the adhesive layer. The release force increasing agent contained in the pressure-sensitive adhesive composition in such a form can effectively contribute to increasing the water release force and improving the water resistance reliability.

When the adhesive layer contains a peel force increasing agent, the content of the peel force increasing agent in the adhesive layer can be set so as to obtain a desired effect of use, and is not particularly limited. The amount of the peel force increasing agent can be, for example, 0.005 parts by weight or more per 100 parts by weight of the acrylic polymer contained in the adhesive composition of the adhesive layer. The content of the release force increasing agent per 100 parts by weight of the acrylic polymer is usually suitably 0.01 parts by weight or more, preferably 0.03 parts by weight or more, for example 0.05 parts by weight or more. The amount may be at least 0.08 parts by weight. In some embodiments, the content of the release force increasing agent may be 0.10 parts by weight or more, 0.20 parts by weight or more, or 0.30 parts by weight or more. By increasing the content of the peel force increasing agent, the effect of increasing the peel force can be exhibited. Furthermore, depending on the usage mode, if the period until the peeling force increases over time at room temperature is too short, the reworkable period becomes too short, which may cause problems such as complicating process control. From this point of view, in some embodiments, the content of the peel force increasing agent per 100 parts by weight of the acrylic polymer in the adhesive composition may be, for example, 5 parts by weight or less, 3 parts by weight or less, The amount may be 1 part by weight or less, 0.7 part by weight or less, 0.5 part by weight or less, or 0.3 part by weight or less.

(water affinity agent)
The adhesive layer in the technology disclosed herein may contain a water-compatible agent, if desired. By containing a water-compatible agent in the adhesive layer, the peeling force can be effectively reduced using an aqueous liquid such as water. The reason for this is not particularly limited, but in general, water affinity agents tend to be unevenly distributed on the surface of the adhesive layer (adhesive surface) because they have a hydrophilic region, thereby effectively reducing the water affinity of the adhesive surface. It is thought that the adhesive layer exhibits a good enhancing effect and effectively reduces the peel force when the adhesive layer comes into contact with water.

As the water-compatible agent, one that is liquid at room temperature (approximately 25° C.) can be preferably used from the viewpoint of ease of preparation of the adhesive composition. One type of water-compatible agent can be used alone or two or more types can be used in combination.

In some embodiments, at least one compound A selected from a surfactant and a compound having a polyoxyalkylene skeleton can be used as the hydrophilic agent. As the surfactant and the compound having a polyoxyalkylene skeleton, one or more types of known surfactants and compounds having a polyoxyalkylene skeleton can be used without particular limitation. It goes without saying that among the surfactants mentioned above, there are compounds having a polyoxyalkylene skeleton, and vice versa.

As the surfactant that can be used as compound A, known nonionic surfactants, anionic surfactants, cationic surfactants, etc. can be used. Among these, nonionic surfactants are preferred. One kind of surfactant can be used alone or two or more kinds can be used in combination.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, and polyoxyethylene oleyl ether; Polyoxyethylene alkylphenyl ethers such as oxyethylene nonylphenyl ether; Sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate; polyoxyethylene sorbitan monolaurate, polyoxyethylene Polyoxyethylene sorbitan such as sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc. Fatty acid ester; polyoxyethylene glyceryl ether fatty acid ester; polyoxyethylene-polyoxypropylene block copolymer; and the like. These nonionic surfactants can be used alone or in combination of two or more.

Examples of anionic surfactants include alkylbenzene sulfonates, such as nonylbenzene sulfonate, dodecylbenzene sulfonate (e.g. sodium dodecylbenzene sulfonate); lauryl sulfate (e.g. sodium lauryl sulfate, ammonium lauryl sulfate), Alkyl sulfates such as octadecyl sulfate; fatty acid salts; polyoxyethylene alkyl ether sulfates such as polyoxyethylene octadecyl ether sulfate, polyoxyethylene lauryl ether sulfate (e.g. sodium polyoxyethylene alkyl ether sulfate), polyoxy Polyoxyethylene alkylphenyl ether sulfates such as ethylene lauryl phenyl ether sulfate (e.g., ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, etc.), polyoxyethylene styrenated phenyl ether sulfates, etc. Polyether sulfates; polyoxyethylene alkyl ether phosphates such as polyoxyethylene stearyl ether phosphates and polyoxyethylene lauryl ether phosphates; sodium salts, potassium salts, etc. of the above polyoxyethylene alkyl ether phosphates polyoxyethylene alkyl ether phosphate ester salt; sulfosuccinate such as lauryl sulfosuccinate, polyoxyethylene lauryl sulfosuccinate (e.g., sodium polyoxyethylene alkyl sulfosuccinate); polyoxyethylene alkyl ether acetate; etc. can be mentioned. When the anionic surfactant forms a salt, the salt may be, for example, a metal salt (preferably a monovalent metal salt) such as a sodium salt, a potassium salt, a calcium salt, a magnesium salt, an ammonium salt, an amine salt, etc. It can be. Anionic surfactants can be used alone or in combination of two or more.

In some embodiments, for example, anionic surfactants having at least one of -POH, -COH, and -SOH groups may be preferably used. Among these, surfactants having a -POH group are preferred. Such surfactants typically contain a phosphate ester structure, such as monoesters of phosphoric acid (ROP(=O)(OH) ₂ ; where R is a monovalent organic group), diesters, etc. ((RO) ₂ P(=O)OH; where R is the same or different monovalent organic group), a mixture containing both monoesters and diesters, and the like. A preferred example of the surfactant having a -POH group is polyoxyethylene alkyl ether phosphate. The number of carbon atoms of the alkyl group in the polyoxyethylene alkyl ether phosphate may be, for example, 6 to 20, 8 to 20, 10 to 20, 12 to 20, or 14 to 20.

Examples of cationic surfactants include polyether amines such as polyoxyethylene laurylamine and polyoxyethylene stearylamine. One type of cationic surfactant can be used alone or two or more types can be used in combination.

Examples of compounds having a polyoxyalkylene skeleton that can be used as compound A include polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); polyethers containing polyoxyethylene units, and polyoxypropylene units. Polyethers, compounds containing oxyethylene units and oxypropylene units (the arrangement of these units may be random or block-like); derivatives thereof; etc. can be used. Moreover, among the above-mentioned surfactants, compounds having a polyoxyalkylene skeleton can also be used. These can be used alone or in combination of two or more. Among these, it is preferable to use a compound containing a polyoxyethylene skeleton (also referred to as a polyoxyethylene segment), and PEG is more preferable.

The molecular weight (chemical formula weight) of the compound having a polyoxyalkylene skeleton (e.g. polyethylene glycol) is not particularly limited, and is suitably less than 1,000, for example. 500 or less). The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (for example, polyethylene glycol) is not particularly limited, and those having a molecular weight of about 100 or more (for example, about 200 or more, furthermore, about 300 or more) are preferably used.

Other examples of water-compatible agents include water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid. One type of water-soluble polymer can be used alone or two or more types can be used in combination. In the technology disclosed herein, as the water affinity agent, one or more types of compound A may be used, one or more types of water-soluble polymers may be used, or a combination of these may be used. It's okay.

The HLB of the water affinity agent is not particularly limited, and is, for example, 3 or more, suitably about 6 or more, and may be 8 or more (for example, 9 or more). In some preferred embodiments, the hydrophilic agent has an HLB of 10 or more. Thereby, water releasability tends to be favorably expressed. The HLB is more preferably 11 or more, still more preferably 12 or more, particularly preferably 13 or more (for example, 14 or more). By including a water affinity agent (typically a surfactant) having an HLB in the above range in the adhesive layer, water releasability can be more effectively expressed. The upper limit of the HLB is 20 or less, and may be, for example, 18 or less, 16 or less, or 15 or less.

Note that HLB in this specification is Hydrophile-Lipophile Balance according to Griffin, and is a value representing the degree of affinity of a surfactant for water and oil, and the ratio of hydrophilicity to lipophilicity is between 0 and 20. It is expressed as a numerical value. The definition of HLB is given by W. C. Griffin: J. Soc. Cosmetic Chemists, 1,311 (1949), co-authored by Etomi Takahashi, Yoshiro Namba, Motoo Koike, and Masao Kobayashi, "Surfactant Handbook", 3rd edition, Kogaku Toshosha Publishing, November 25, 1970, p179- As described in No. 182, etc. The water affinity agent having the above-mentioned HLB can be selected based on the technical common knowledge of those skilled in the art, by taking into consideration the above-mentioned references as necessary.

It is preferable that such a water affinity agent is contained in the adhesive layer in a free form. As the water-compatible agent, one that is liquid at room temperature (approximately 25° C.) is preferably used from the viewpoint of ease of preparing the adhesive composition.

The adhesive layer containing the water-compatible agent is typically formed from the adhesive composition A containing the water-compatible agent. The pressure-sensitive adhesive composition A may be any of the above-mentioned water-dispersed pressure-sensitive adhesive compositions, solvent-type pressure-sensitive adhesive compositions, active energy ray-curable pressure-sensitive adhesive compositions, and hot-melt pressure-sensitive adhesive compositions. In some preferred embodiments, the adhesive layer containing the water affinity agent may be an adhesive layer formed from a photocurable or solvent-based adhesive composition A. In such an adhesive layer, the effect of adding a water-compatible agent can be preferably exhibited. The adhesive layer may have photocrosslinkability.

The content of the water affinity agent in the adhesive layer is not particularly limited, and can be set so that the effect of using the water affinity agent is appropriately exhibited. In some embodiments, the content of the water affinity agent is, for example, 0.001 parts by weight or more per 100 parts by weight of monomer components constituting the polymer (e.g., acrylic polymer) contained in the adhesive layer. The content is suitably 0.01 parts by weight or more, 0.03 parts by weight or more, 0.07 parts by weight or more, or 0.1 parts by weight or more. In some preferred embodiments, the content of the hydrophilic agent may be, for example, 0.2 parts by weight or more, based on 100 parts by weight of the monomer component, and may be 0.5 parts by weight or more from the viewpoint of obtaining higher effects. The amount may be 1.0 parts by weight or more, or 1.5 parts by weight or more. Further, from the viewpoint of suppressing excessive water diffusion into the bulk of the adhesive layer, in some embodiments, the amount of the water affinity agent used is, for example, 20 parts by weight or less with respect to 100 parts by weight of the monomer component. Generally, the amount is suitably 10 parts by weight or less, preferably 5 parts by weight or less, and may be 3 parts by weight or less. It is preferable that the content of the water-compatible agent is not too large, also from the viewpoint of improving the transparency of the adhesive layer. For example, in some embodiments, the content of the hydrophilic agent based on 100 parts by weight of monomer components may be less than 2 parts by weight, less than 1 part by weight, less than 0.7 parts by weight, or 0.3 parts by weight. It may be less than 0.2 parts by weight. Water affinity agents having an HLB of 10 or more tend to exhibit good water releasability even when used in small amounts.

(Crosslinking agent)
A crosslinking agent may be used in the adhesive layer as necessary for the purpose of crosslinking within the adhesive layer or between the adhesive layer and its adjacent surface. The crosslinking agent may be contained in the adhesive layer in the form after the crosslinking reaction, or may be contained in the form before the crosslinking reaction. The type of crosslinking agent is not particularly limited, and is selected from among conventionally known crosslinking agents so that the crosslinking agent exhibits an appropriate crosslinking function within the adhesive layer, depending on the composition of the adhesive composition, for example. be able to. Examples of crosslinking agents that can be used include isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, melamine crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, and metals. Examples include chelate crosslinking agents, metal salt crosslinking agents, hydrazine crosslinking agents, and amine crosslinking agents. These can be used alone or in combination of two or more.

As the isocyanate-based crosslinking agent, a polyfunctional isocyanate compound having two or more functionalities can be used. For example, aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl) thiophosphate, diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic such as hexamethylene diisocyanate. Isocyanates; and the like. Commercially available products include trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), Examples include isocyanate adducts such as "Coronate HL") and isocyanurates of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX").

As the epoxy crosslinking agent, those having two or more epoxy groups in one molecule can be used without particular limitation. Epoxy crosslinking agents having 3 to 5 epoxy groups in one molecule are preferred. Specific examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylene diamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and 1,6-hexane. Examples include diol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include Mitsubishi Gas Chemical's product names "TETRAD-X" and "TETRAD-C," DIC's product name "Epicron CR-5L," and Nagase ChemteX's product name. Examples include "Denacol EX-512" under the name "Denacol EX-512" and "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd.

As the oxazoline crosslinking agent, those having one or more oxazoline groups in one molecule can be used without particular limitation.
Examples of aziridine-based crosslinking agents include trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)], etc. It will be done.
As the carbodiimide crosslinking agent, a low molecular compound or a high molecular compound having two or more carbodiimide groups can be used.

In some embodiments, peroxides may be used as crosslinking agents. Peroxides include di(2-ethylhexyl) peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate. , t-hexyl peroxy pivalate, t-butyl peroxy pivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxyisobutyrate, di- Examples include benzoyl peroxide. Among these, peroxides particularly excellent in crosslinking reaction efficiency include di(4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, dibenzoyl peroxide, and the like. In addition, when a peroxide is used as the polymerization initiator, it is also possible to use the peroxide remaining without being used in the polymerization reaction in the crosslinking reaction. In that case, the remaining amount of peroxide may be determined, and if the proportion of peroxide is less than a predetermined amount, peroxide may be added to the predetermined amount as necessary. Peroxide can be quantified by the method described in Japanese Patent No. 4,971,517.

The content of the crosslinking agent (if two or more types of crosslinking agents are included, the total amount thereof) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits adhesive properties such as adhesive strength and cohesive force in a well-balanced manner, the content of the crosslinking agent is usually approximately 100 parts by weight based on 100 parts by weight of the acrylic polymer contained in the pressure-sensitive adhesive composition. It is appropriate that the amount is 5 parts by weight or less, preferably about 0.001 to 5 parts by weight, more preferably about 0.001 to 4 parts by weight, and about 0.001 to 3 parts by weight. It is more preferable to do so. Alternatively, the pressure-sensitive adhesive composition may not contain a crosslinking agent as described above. When a photocurable adhesive composition is used as the adhesive composition disclosed herein, the adhesive composition may be substantially free of crosslinking agents such as isocyanate crosslinking agents. Here, when the pressure-sensitive adhesive composition does not substantially contain a crosslinking agent (typically an isocyanate-based crosslinking agent), it means that the amount of the crosslinking agent is less than 0.05 parts by weight (for example, less than 0.01 part by weight).

A crosslinking catalyst may be used to advance the crosslinking reaction more effectively. Examples of the crosslinking catalyst include metal crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nathem, butyltin oxide, and dioctyltin dilaurate. Among these, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of crosslinking catalyst used is not particularly limited. The amount of the crosslinking catalyst used per 100 parts by weight of the acrylic polymer in the adhesive composition may be, for example, approximately 0.0001 parts by weight or more and 1 part by weight or less, and 0.001 parts by weight or more and 0.1 parts by weight or less. It may be 0.005 parts by weight or more and 0.5 parts by weight or less.

(polyfunctional monomer)
A polyfunctional monomer may be used in the adhesive layer, if necessary. Polyfunctional monomers can be used in place of or in combination with the above-mentioned crosslinking agents, and can be useful for purposes such as adjusting cohesive force. As the polyfunctional monomer, a compound having two or more ethylenically unsaturated groups can be used. The polyfunctional monomer may be contained in the adhesive layer in an unreacted form, or may be contained in the adhesive layer in a reacted (post-crosslinked) form. The adhesive layer containing an unreacted polyfunctional monomer has photocrosslinkability, which allows the polyfunctional monomer to react and form a crosslinked structure by irradiating the adhesive layer with active energy rays such as ultraviolet rays. It can be an adhesive layer.

Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, Pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecane Diol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl Examples include diol (meth)acrylate, hexyl diol di(meth)acrylate, and the like. Among them, trimethylolpropane tri(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be preferably used. The polyfunctional monomers can be used alone or in combination of two or more.

The amount of the polyfunctional monomer used varies depending on its molecular weight, number of functional groups, etc., but it is usually in the range of about 0.01 parts by weight to 3.0 parts by weight per 100 parts by weight of the acrylic polymer. Appropriate. In some embodiments, the amount of the polyfunctional monomer used per 100 parts by weight of the acrylic polymer may be, for example, 0.02 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more. The amount may be at least 1.0 parts by weight, or at least 2.0 parts by weight. Higher cohesive strength tends to be obtained by increasing the amount of polyfunctional monomer used. On the other hand, from the viewpoint of avoiding deterioration of adhesion between the adhesive layer and the adjacent layer due to excessive improvement in cohesive force, the amount of the polyfunctional monomer to be used per 100 parts by weight of the acrylic polymer is, for example, 10 parts by weight or less. The amount may be 5.0 parts by weight or less, or may be 3.0 parts by weight or less.

(acrylic oligomer)
The pressure-sensitive adhesive composition (and thus the pressure-sensitive adhesive layer) disclosed herein can have improved cohesive force, improved adhesion to a surface adjacent to the pressure-sensitive adhesive layer (for example, the surface of a base material, etc.), etc. From this viewpoint, an acrylic oligomer can be contained. As the acrylic oligomer, it is preferable to use a polymer whose Tg is higher than that of the acrylic polymer.

The Tg of the acrylic oligomer is not particularly limited, and may be, for example, about 20°C or more and 300°C or less. The Tg may be, for example, about 30°C or more, about 40°C or more, about 60°C or more, about 80°C or more, or about 100°C or more. As the Tg of the acrylic oligomer increases, the effect of improving cohesive force generally tends to increase. Further, from the viewpoint of anchoring ability to the base material, shock absorption property, etc., the Tg of the acrylic oligomer may be, for example, about 250°C or less, about 200°C or less, about 180°C or less, or about 150°C or less. But that's fine. Note that the Tg of the acrylic oligomer is a value calculated based on the Fox formula, similar to the Tg of the acrylic polymer corresponding to the composition of the monomer components described above.

The Mw of the acrylic oligomer is typically about 1,000 or more and less than about 30,000, preferably about 1,500 or more and less than about 10,000, and more preferably about 2,000 or more and less than about 5,000. When Mw is within the above range, the effect of improving cohesion and adhesion to adjacent surfaces is likely to be suitably exhibited. The Mw of the acrylic oligomer can be measured by gel permeation chromatography (GPC) and determined as a value in terms of standard polystyrene. Specifically, the measurement is performed using HPLC8020 manufactured by Tosoh Corporation with two columns of TSKgelGMH-H (20) at a flow rate of about 0.5 mL/min using tetrahydrofuran solvent.

The monomer components constituting the acrylic oligomer include the various (meth)acrylic acid C _1-20 alkyl esters mentioned above; the various alicyclic hydrocarbon group-containing (meth)acrylates mentioned above; the various aromatic carbonizations mentioned above; Examples include (meth)acrylate monomers such as hydrogen group-containing (meth)acrylate; (meth)acrylate obtained from terpene compound derivative alcohol; These can be used alone or in combination of two or more.

Acrylic oligomers include alkyl (meth)acrylates in which the alkyl group has a branched structure, such as isobutyl (meth)acrylate and t-butyl (meth)acrylate; (meth)acrylates containing alicyclic hydrocarbon groups and aromatic hydrocarbons. From the viewpoint of improving adhesiveness, it is preferable that an acrylic monomer having a relatively bulky structure, such as group-containing (meth)acrylate, be included as a monomer unit. Furthermore, when employing ultraviolet rays during the synthesis of acrylic oligomers or the production of adhesive layers, monomers having a saturated hydrocarbon group at the ester end are preferable because they are less likely to inhibit polymerization, such as alkyl Alkyl (meth)acrylates in which groups have a branched structure and (meth)acrylates containing saturated alicyclic hydrocarbon groups can be suitably used.

The proportion of (meth)acrylate monomers in all monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (e.g. 80% by weight). 90% by weight or more). In one preferred embodiment, the acrylic oligomer has a monomer composition consisting essentially of one or more (meth)acrylate monomers. When the monomer component contains an alicyclic hydrocarbon group-containing (meth)acrylate and a (meth)acrylic acid C _1-20 alkyl ester, the weight ratio thereof is not particularly limited, and is, for example, 10/90 to 90/10. range, 20/80 to 80/20, 70/30 to 30/70, etc.

As the constituent monomer components of the acrylic oligomer, in addition to the above-mentioned (meth)acrylate monomers, functional group-containing monomers can be used as necessary. Examples of functional group-containing monomers include monomers having a nitrogen atom-containing heterocycle such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate; Examples include amide group-containing monomers such as N-diethyl (meth)acrylamide; carboxy group-containing monomers such as AA and MAA; and hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate. These functional group-containing monomers can be used alone or in combination of two or more. When using a functional group-containing monomer, the proportion of the functional group-containing monomer in the total monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and For example, it can be 15% by weight or less, 10% by weight or less, or 7% by weight or less.

Suitable acrylic oligomers include, for example, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), In addition to homopolymers of 1-adamantyl methacrylate (ADMA) and 1-adamantyl acrylate (ADA), copolymers of DCPMA and MMA, copolymers of DCPMA and IBXMA, and copolymers of ADA and methyl methacrylate (MMA). copolymer of CHMA and isobutyl methacrylate (IBMA), copolymer of CHMA and IBXMA, copolymer of CHMA and acryloylmorpholine (ACMO), copolymer of CHMA and diethylacrylamide (DEAA), Examples include copolymers of CHMA and AA.

Acrylic oligomers can be formed by polymerizing their constituent monomer components. The polymerization method and polymerization mode are not particularly limited, and various conventionally known polymerization methods (e.g., solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be employed in an appropriate mode. The types of polymerization initiators (for example, azo polymerization initiators) that can be used as necessary are generally the same as those exemplified for the synthesis of acrylic polymers, and the amount of polymerization initiators and chain transfer agents optionally used The amount of (for example, mercaptans) is appropriately set based on common technical knowledge so as to obtain a desired molecular weight, so a detailed explanation will be omitted.

When the adhesive composition contains an acrylic oligomer, the content can be, for example, 0.01 parts by weight or more based on 100 parts by weight of the acrylic polymer, from the viewpoint of obtaining higher effects. The amount may be 0.05 part by weight or more, 0.1 part by weight or more, or 0.2 part by weight or more. In addition, from the viewpoint of compatibility with the acrylic polymer, the content of the acrylic oligomer is usually less than 50 parts by weight, preferably less than 30 parts by weight, and more preferably less than 25 parts by weight. For example, it may be 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less.

The adhesive composition disclosed herein may contain a tackifier resin (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc. tackifier resin), a viscosity modifier (e.g., thickener), if necessary. We use various additives commonly used in the field of adhesive compositions, such as leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, antioxidants, and anti-aging agents. It may be included as other optional ingredients. Regarding such various additives, conventionally known ones can be used in a conventional manner, and since they do not particularly characterize the present invention, detailed explanations will be omitted.
In addition, since the technology disclosed herein can exhibit good adhesive strength without using the above-mentioned tackifying resin, the content of the above-mentioned tackifying resin in the pressure-sensitive adhesive composition is determined by the amount of the acrylic polymer. For example, the amount may be less than 10 parts by weight, or even less than 5 parts by weight, per 100 parts by weight. The content of the tackifier resin may be less than 1 part by weight (for example, less than 0.5 part by weight), or less than 0.1 part by weight (0 part by weight or more and less than 0.1 part by weight). , the pressure-sensitive adhesive composition may not contain a tackifying resin.

Since the adhesive composition disclosed herein is used for optical purposes, it may have predetermined optical properties (eg, transparency) even after the adhesive layer is formed. From the viewpoint of such optical properties, it is preferable that the amount of components other than the acrylic polymer in the pressure-sensitive adhesive composition is limited. In the technology disclosed herein, the amount of components other than the acrylic polymer in the adhesive composition is usually about 30% by weight or less, suitably about 15% by weight or less, and preferably about 15% by weight or less. It is 12% by weight or less (for example, approximately 10% by weight or less). The amount of components other than the acrylic polymer in the adhesive composition according to one embodiment may be approximately 5% by weight or less, approximately 3% by weight or less, and approximately 1.5% by weight or less ( For example, it may be approximately 1% by weight or less. A composition in which the amount of components other than the acrylic polymer is limited in this way can be preferably employed in a photocurable pressure-sensitive adhesive composition.

<Adhesive layer>
The adhesive layer constituting the adhesive sheet disclosed herein may be a cured layer of an adhesive composition. That is, the adhesive layer can be formed by applying (for example, coating) an adhesive composition to a suitable surface and then appropriately performing a curing treatment. When performing two or more types of curing treatments (drying, crosslinking, polymerization, etc.), these can be performed simultaneously or in multiple stages.
In pressure-sensitive adhesive compositions using partial polymers of monomer components (acrylic polymer syrup), a final copolymerization reaction is typically performed as the curing treatment. That is, the partially polymerized product is further subjected to a copolymerization reaction to form a complete polymerized product. For example, in the case of a photocurable adhesive composition, light irradiation is performed. Curing treatments such as crosslinking and drying may be performed as necessary. For example, if it is necessary to dry a photocurable adhesive composition (for example, in the case of a photocurable adhesive composition in which a partial polymer of a monomer component is dissolved in an organic solvent), dry the composition. It is preferable to perform photocuring after this.
In an adhesive composition using a complete polymer, typically, as the curing treatment, treatments such as drying (heat drying) and crosslinking are performed as necessary. In the case of a solvent-based adhesive composition imparted with photo-crosslinking properties by the addition of a polyfunctional monomer, the photo-crosslinking may be carried out after drying the composition. Here, the period after drying the composition may be the period after the pressure-sensitive adhesive sheet obtained through the drying is bonded to an adherend. The pressure-sensitive adhesive sheet disclosed herein can be used in an embodiment in which it is attached to an adherend by a method that includes photo-crosslinking after being attached to the adherend.
An adhesive layer having a multilayer structure of two or more layers can be produced by bonding together adhesive layers formed in advance. Alternatively, a second adhesive layer may be formed by applying a pressure-sensitive adhesive composition onto a first pressure-sensitive adhesive layer formed in advance and curing the pressure-sensitive adhesive composition. When the adhesive layer of the adhesive sheet used in an application mode in which the adhesive sheet is photo-crosslinked after being bonded to an adherend has a multilayer structure, the adhesive layer to be photocrosslinked may be a part of the layers included in the multilayer structure ( For example, it may be one layer) or all layers.

The adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, and a spray coater. In a pressure-sensitive adhesive sheet having a base material, the method of providing the pressure-sensitive adhesive layer on the base material may be a direct method in which the pressure-sensitive adhesive composition is directly applied to the base material to form the pressure-sensitive adhesive layer. A transfer method may be used in which the adhesive layer formed on the surface is transferred to the base material.

The thickness of the adhesive layer is not particularly limited, and may be, for example, about 3 μm to 2000 μm. In some embodiments, the thickness of the adhesive layer may be, for example, 5 μm or more, suitably 10 μm or more, preferably 20 μm or more, and more, from the viewpoint of adhesion to the adherend such as step followability. Preferably it is 30 μm or more. The thickness of the adhesive layer may be 50 μm or more, more than 50 μm, 70 μm or more, 100 μm or more, or 120 μm or more. Further, in some embodiments, the thickness of the adhesive layer may be, for example, 1000 μm or less, 700 μm or less, or 500 μm or less, from the viewpoint of preventing adhesive residue from occurring due to cohesive failure of the adhesive layer. , 300 μm or less, further 200 μm or less, or 170 μm or less. The technology disclosed herein can be suitably implemented in the form of a pressure-sensitive adhesive sheet in which the thickness of the pressure-sensitive adhesive layer may be 130 μm or less, 90 μm or less, or 60 μm or less (for example, 40 μm or less). In addition, in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a multilayer structure of two or more layers, the thickness of the pressure-sensitive adhesive layer is the thickness from the pressure-sensitive adhesive surface to be attached to the adherend to the surface opposite to the pressure-sensitive adhesive surface. That's what I mean.

(Photocrosslinkable adhesive layer)
In some embodiments of the adhesive sheet disclosed herein, the adhesive sheet has a photo-crosslinkable adhesive layer composed of a photo-crosslinkable adhesive. In one preferred embodiment, the adhesive layer constituting the adhesive surface of the adhesive sheet is a photocrosslinkable adhesive layer. A pressure-sensitive adhesive sheet having a photo-crosslinkable pressure-sensitive adhesive layer can have improved deformation resistance by photo-crosslinking the pressure-sensitive adhesive layer. As a result, the surface shape of the adhesive layer can be easily followed when attached to an adherend, and a bond with high deformation resistance can be formed by photo-crosslinking the adhesive layer after attachment. A pressure-sensitive adhesive layer that has good surface conformability can be suitably brought into close contact with the surface of an adherend by deforming (absorbing the difference in level) along the steps that may exist on the surface of the adherend.

The photocrosslinkable adhesive constituting the photocrosslinkable adhesive layer may be imparted with photocrosslinkability by, for example, containing an unreacted polyfunctional monomer as described above; It may also be one that is imparted with photo-crosslinking properties by containing a polymer. Each of the polyfunctional monomers and photocrosslinkable polymers can be used singly or in combination of two or more. It may be a photo-crosslinkable adhesive containing a combination of a polyfunctional monomer and a photo-crosslinkable polymer. The photocrosslinkable adhesive may contain a photoinitiator depending on the type of photocrosslinking.

A preferred example of the photocrosslinkable polymer is a polymer having a benzophenone structure in its side chain. A pressure-sensitive adhesive containing such a polymer can be photo-crosslinked using the benzophenone structure described above. As the polymer having a benzophenone structure in its side chain, an acrylic polymer having a benzophenone structure in its side chain can be preferably used.
Another suitable example of the above-mentioned photocrosslinkable polymer includes a polymer having a carbon-carbon double bond. A pressure-sensitive adhesive containing such a polymer can be photo-crosslinked by reacting the carbon-carbon double bonds. A preferred example of a polymer having a carbon-carbon double bond is, for example, an acrylic polymer having a (meth)acryloyl group introduced into the side chain. Such an acrylic polymer can be used, for example, to combine a primary acrylic polymer into which a hydroxyl group has been introduced by copolymerization with a compound having a carbon-carbon double bond and an isocyanate group so that the carbon-carbon double bond does not disappear. It can be obtained by reacting with.

<Base material>
The pressure-sensitive adhesive sheet according to some embodiments may be in the form of a pressure-sensitive adhesive sheet with a base material, which includes a base material bonded to the other back surface of the pressure-sensitive adhesive layer. The material of the base material is not particularly limited, and can be appropriately selected depending on the purpose and manner of use of the pressure-sensitive adhesive sheet. Non-limiting examples of base materials that can be used include polyolefin films mainly composed of polyolefins such as polypropylene and ethylene-propylene copolymers; polyester films mainly composed of polyesters such as polyethylene terephthalate and polybutylene terephthalate; Plastic films such as polyvinyl chloride film whose main component is polyvinyl chloride; Foam sheets made of foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; Various fibrous materials (natural fibers such as hemp and cotton, Woven fabrics and non-woven fabrics, such as synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc., alone or in combination; Papers such as Japanese paper, high-quality paper, kraft paper, and crepe paper; Aluminum foil, copper Examples include metal foil such as foil; and the like. A base material having a composite structure of these materials may also be used. Examples of base materials having such a composite structure include base materials having a structure in which metal foil and the above-mentioned plastic film are laminated, plastic sheets reinforced with inorganic fibers such as glass cloth, and the like.

Various films (hereinafter also referred to as support films) can be preferably used as the base material of the pressure-sensitive adhesive sheet disclosed herein. The support film may be a porous film such as a foam film or a non-woven fabric sheet, or a non-porous film, or may be a laminated layer of a porous layer and a non-porous layer. It may also be a structural film. In some embodiments, as the above-mentioned support film, one that includes a base film that can independently maintain its shape (self-supporting or independent) can be preferably used. Here, the term "resin film" refers to a resin film that has a non-porous structure and typically is substantially void-free. Therefore, the resin film is a concept that is distinguished from foam films and nonwoven fabrics. The resin film may have a single-layer structure or a multi-layer structure of two or more layers (for example, a three-layer structure).

Examples of the resin material constituting the resin film include polyester, polyolefin, polycycloolefin derived from a monomer having an aliphatic ring structure such as norbornene structure, polyamide (PA) such as nylon 6, nylon 66, and partially aromatic polyamide. , polyimide (PI) such as transparent polyimide (CPI), polyamideimide (PAI), polyetheretherketone (PEEK), polyethersulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), Fluororesins such as ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), polystyrene, ABS resin, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene (PTFE), acrylic resins such as polymethyl methacrylate, Resins such as cellulose polymers such as diacetyl cellulose and triacetyl cellulose (TAC), vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, and epoxy polymers can be used. The resin film may be formed using a resin material containing only one type of such resin, or may be formed using a resin material that is a blend of two or more types of resin. Good too. The resin film may be unstretched or may be stretched (for example, uniaxially or biaxially stretched).

Suitable examples of the resin material constituting the resin film include polyester resin, PPS resin, polyolefin resin, and polyimide resin. Here, the polyester resin refers to a resin containing polyester in a proportion exceeding 50% by weight. Similarly, PPS resin refers to a resin containing PPS in a proportion exceeding 50% by weight, polyolefin resin refers to a resin containing polyolefin in a proportion exceeding 50% by weight, and polyimide resin refers to a resin containing polyolefin in a proportion exceeding 50% by weight. It refers to a resin containing polyimide in a proportion exceeding 50% by weight.

As the polyester resin, a polyester resin containing as a main component a polyester obtained by polycondensing a dicarboxylic acid and a diol is typically used. Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate, and the like.

As the polyolefin resin, one type of polyolefin can be used alone or two or more types of polyolefin can be used in combination. The polyolefin may be, for example, a homopolymer of α-olefins, a copolymer of two or more α-olefins, a copolymer of one or more α-olefins and another vinyl monomer, or the like. Specific examples include ethylene-propylene copolymers such as polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene propylene rubber (EPR); Examples include butene copolymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, ethylene-ethyl acrylate copolymers, and the like. Both low density (LD) and high density (HD) polyolefins can be used. Examples of polyolefin resin films include unoriented polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, and medium density polyethylene (MDPE). films, high-density polyethylene (HDPE) films, polyethylene (PE) films that are a blend of two or more types of polyethylene (PE), and PP/PE blend films that are a blend of polypropylene (PP) and polyethylene (PE).

Specific examples of resin films that can be preferably used as the base material include PET film, PEN film, PPS film, PEEK film, CPI film, CPP film, and OPP film. Preferred examples from the viewpoint of strength include PET film, PEN film, PPS film, PEEK film, and CPI film. Preferred examples from the viewpoint of availability, dimensional stability, optical properties, etc. include PET film, CPI film, and TAC film.

Known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, anti-blocking agents, etc. may be added to the resin film as necessary. I can do it. The blending amount of the additive is not particularly limited, and can be appropriately set depending on the use of the pressure-sensitive adhesive sheet.

The method for producing the resin film is not particularly limited. For example, conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be appropriately employed.

The base material may be substantially composed of such a resin film. Alternatively, the base material may include an auxiliary layer in addition to the resin film. Examples of the above-mentioned auxiliary layers include optical property adjustment layers (e.g., colored layers, antireflection layers), printing layers or laminate layers for imparting a desired appearance to the base material or adhesive sheet, antistatic layers, and undercoat layers. , a surface treatment layer such as a release layer. Further, the support material may be an optical member described later.

The thickness of the base material is not particularly limited, and can be selected depending on the purpose and manner of use of the adhesive sheet. The thickness of the base material may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the base material decreases, the flexibility of the adhesive sheet and the ability to follow the surface shape of the adherend tend to improve. Further, from the viewpoint of handleability, processability, etc., the thickness of the base material may be, for example, 2 μm or more, and may be more than 5 μm or more than 10 μm. In some embodiments, the thickness of the substrate may be, for example, 20 μm or more, 35 μm or more, or 55 μm or more.

The side of the base material that will be bonded to the adhesive layer is treated with corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of an undercoat (primer), and antistatic treatment as necessary. A conventionally known surface treatment such as the like may be applied. Such surface treatment may be a treatment for improving the adhesion between the base material and the adhesive layer, in other words, the ability of the adhesive layer to anchor to the base material. The composition of the primer is not particularly limited, and can be appropriately selected from known primers. The thickness of the undercoat layer is not particularly limited, but it is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm.

The surface of the base material opposite to the side to be bonded to the adhesive layer (hereinafter also referred to as the back surface) may be treated with peeling treatment, adhesiveness or tackiness improvement treatment, antistatic treatment, etc. as necessary. A conventionally known surface treatment may be applied. For example, by surface-treating the back surface of the base material with a release agent, the unwinding force of the pressure-sensitive adhesive sheet wound into a roll can be reduced. As the release agent, silicone release agent, long chain alkyl release agent, olefin release agent, fluorine release agent, fatty acid amide release agent, molybdenum sulfide, silica powder, etc. can be used. .

<Additional adhesive layer>
The pressure-sensitive adhesive sheet disclosed herein may have a pressure-sensitive adhesive layer that may be additionally disposed in addition to the pressure-sensitive adhesive layer described above. The additional adhesive layer may be, for example, an acrylic adhesive, a rubber adhesive (natural rubber type, synthetic rubber type, a mixture thereof, etc.), a silicone adhesive, a polyester adhesive, a urethane adhesive, The adhesive layer may include one or more types of adhesives selected from various known adhesives such as polyether adhesives, polyamide adhesives, and fluorine adhesives. From the viewpoint of transparency, weather resistance, etc., in some embodiments, an acrylic adhesive may be preferably employed as a constituent material of the additional adhesive layer. Regarding other matters of the additional adhesive layer, the same configuration as the adhesive layer described above can be adopted, or an appropriate configuration can be adopted depending on the use and purpose based on publicly known or commonly used technology and common technical knowledge. Therefore, detailed explanation will be omitted here.

<Application>
The use of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, and it can be used for various purposes. For example, the adhesive sheet disclosed herein can be used for purposes such as fixing, joining, molding, decorating, protecting, and supporting members constituting various products. The materials constituting at least the surface of the above member include, for example, glass such as alkali glass and non-alkali glass; metal materials such as resin film, stainless steel (SUS), and aluminum; ceramic materials such as alumina and silica; acrylic resin, and ABS. It can be a resin material such as resin, polycarbonate resin, polystyrene resin, transparent polyimide resin, etc. The above-mentioned member may be a member constituting, for example, various types of mobile devices, automobiles, home appliances, and the like. The surface of the above member to which the adhesive sheet is attached may be acrylic-based, polyester-based, alkyd-based, melamine-based, urethane-based, acid-epoxy crosslinked system, or a composite system thereof (for example, acrylic-melamine-based, alkyd-melamine-based ) or a plated surface such as a galvanized steel plate. Further, the above-mentioned member may be any of the support films (for example, resin films) exemplified as materials that can be used for the base material. The adhesive sheet disclosed herein may be, for example, a component of a member with an adhesive sheet in which such a member is bonded to at least one surface of an adhesive layer.

The pressure-sensitive adhesive sheet disclosed herein can be preferably used in an embodiment in which it is attached to an adherend having a glass material on at least the surface. In such an embodiment, the adhesive exhibits good water releasability at the initial stage of application (preferably for a certain period of time after application), and can suitably exhibit the effect of bonding to the adherend with good water resistance and reliability. The adherend may be a plate-shaped body made of a glass material such as alkali glass or non-alkali glass, and may be made of a glass material (typically silicon oxide represented by SiO _x or dioxide represented by SiO ₂ ). It may also be a composite film in which a hydrophilic layer containing (silicone) is formed on a different material such as a resin film. The above-mentioned hydrophilic layer (surface modified layer) can be formed by known methods such as physical vapor deposition (PVD) such as vacuum evaporation, sputtering, and ion plating, and chemical vapor deposition (CVD) such as atomic layer deposition. It can be formed using a membrane method. Alternatively, the hydrophilic layer may be formed by applying a coating agent containing powder of a glass material. The coating agent may or may not contain various organic materials including organic polymer compounds that can be used as binders.

An example of a preferable use of the pressure-sensitive adhesive sheet disclosed herein is optical use. More specifically, the adhesive sheet disclosed herein is used, for example, as an optical adhesive sheet used for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the above-mentioned optical members. A pressure-sensitive adhesive sheet can be preferably used.

The above-mentioned optical member refers to a member having optical properties (for example, polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.). say. The above-mentioned optical member is not particularly limited as long as it has optical properties, but for example, it may be a member constituting a device (optical device) such as a display device (image display device) or an input device, or a member used in these devices. Members include, for example, polarizing plates, wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, antireflection films, hard coat (HC) films, shock absorption films, antifouling films, Photochromic films, light control films, transparent conductive films (ITO films), design films, decorative films, surface protection plates, prisms, lenses, color filters, transparent substrates, and members on which these are laminated (collectively referred to as (sometimes referred to as "functional film"). Note that the above-mentioned "plate" and "film" each include forms such as plate, film, and sheet. For example, "polarizing film" includes "polarizing plate", "polarizing sheet", etc. .

Examples of the above-mentioned display devices include liquid crystal display devices, organic EL (electroluminescence) display devices, PDP (plasma display panels), and electronic paper, and in particular, foldable display devices and vehicle-mounted display devices. , can be preferably applied when expensive members are involved. Furthermore, examples of the input device include a touch panel.

The optical member is not particularly limited, but includes, for example, members (for example, sheet-like, film-like, and plate-like members) made of glass, acrylic resin, polycarbonate, polyethylene terephthalate, metal thin film, and the like. Note that the term "optical member" in this specification also includes members (design films, decorative films, surface protection films, etc.) that serve to decorate and protect while maintaining the visibility of display devices and input devices.

The mode of bonding optical members together using the adhesive sheet disclosed herein is not particularly limited, but includes, for example, (1) a mode of bonding optical members together via the pressure-sensitive adhesive sheet disclosed herein; ) The optical member may be attached to a member other than the optical member via the adhesive sheet disclosed herein, or (3) the adhesive sheet disclosed herein may include an optical member and the optical member may be attached to a member other than the optical member. The adhesive sheet may be attached to an optical member or a member other than an optical member. In the above embodiment (3), the pressure-sensitive adhesive sheet containing an optical member may be, for example, a pressure-sensitive adhesive sheet whose base material is an optical member (for example, an optical film). A pressure-sensitive adhesive sheet containing an optical member as a base material in this manner can also be understood as a pressure-sensitive adhesive optical member (for example, a pressure-sensitive adhesive optical film). Further, when the adhesive sheet disclosed herein is a type of adhesive sheet having a base material, and the functional film is used as the base material, the adhesive sheet disclosed herein is a type of adhesive sheet having a base material, and when the functional film is used as the base material, the adhesive sheet disclosed herein is a type of adhesive sheet having a base material. It can also be understood as an "adhesive functional film" having the adhesive layer disclosed herein on at least one side.

<Water contact angle>
The pressure-sensitive adhesive sheet disclosed herein can be preferably used in an embodiment in which it is attached to a surface exhibiting hydrophilicity such that the contact angle with respect to distilled water is, for example, 60 degrees or less, preferably 50 degrees or less. In some embodiments, the contact angle of the bonding surface may be, for example, 45 degrees or less, 40 degrees or less, 35 degrees or less, or 30 degrees or less. When the contact angle of the bonded surface becomes smaller, water tends to wet and spread along the bonded surface, and the water releasability of the pressure-sensitive adhesive sheet tends to improve. This is preferable from the viewpoint of improving reworkability when producing a member with a pressure-sensitive adhesive sheet by bonding the pressure-sensitive adhesive sheet to the bonding surface. Further, on such a highly hydrophilic surface, for example, in an embodiment in which Compound S is used as a peel force improver, the effect of improving bonding reliability (for example, water resistance reliability) by Compound S can be preferably exhibited.
In addition, if the contact angle of the bonding surface is at least one of the angles mentioned above at the time of bonding the adhesive sheet (for example, 30 minutes before bonding), rework due to the contact angle being below the predetermined value is not possible. A sex-enhancing effect may be exhibited. The lower limit of the contact angle is 0 degrees in principle. In some embodiments, the contact angle of the bonding surface may be greater than 0 degrees, may be greater than or equal to 1 degree, may be greater than or equal to 3 degrees, or may be greater than or equal to 5 degrees. The contact angle of the bonding surface of the member is measured in the same manner as the contact angle of the alkali glass plate described above.

The joint surfaces of the members may be subjected to hydrophilic treatment to reduce the contact angle with distilled water. Examples of the hydrophilic treatment include treatments that contribute to improving hydrophilicity, such as corona treatment, plasma treatment, and treatment to form a hydrophilic layer. The equipment and treatment conditions used for corona treatment and plasma treatment can be set based on conventionally known techniques so that a bonded surface exhibiting a desired contact angle can be obtained.

The hydrophilic layer forming treatment may be a treatment for forming a hydrophilic coating layer. The hydrophilic coating layer can be formed by appropriately selecting from known coating agents that provide a bonding surface exhibiting a desired contact angle, and using the same in a conventional manner. The thickness of the hydrophilic coating layer may be, for example, 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, or, for example, 10 μm or less, 5 μm or less, or 2 μm or less. good.

The hydrophilic layer forming treatment may be a treatment for forming a hydrophilic layer containing an inorganic material. When the hydrophilic layer contains an inorganic material, good water releasability is easily obtained. As the inorganic material, materials that can form a hydrophilic surface are used, including various metal materials including simple substances and alloys of transition metal elements and metalloid elements, and inorganic compounds such as inorganic oxides. The above inorganic materials can be used alone or in combination of two or more. Suitable examples of inorganic materials include oxides such as titanium oxide, zinc oxide, magnesium oxide, aluminum oxide, silicon oxide, cerium oxide, chromium oxide, zirconium oxide, manganese oxide, zinc oxide, iron oxide, tin oxide, and niobium oxide. (inorganic oxides, typically metal oxides). Among these, inorganic oxides such as silicon oxide are used as preferred inorganic materials. In addition to inorganic materials, the hydrophilic layer may or may not contain various organic materials including organic polymer compounds that can be used as coating agents and binders.

The amount of the inorganic material (for example, inorganic oxide such as silicon oxide) in the hydrophilic layer can be set to an appropriate amount that provides the desired hydrophilic surface, and is not limited to a specific range. For example, the content of the inorganic material in the hydrophilic layer can be about 30% by weight or more, suitably about 50% by weight or more (for example, more than 50% by weight), and even about 70% by weight or more. good. In some preferred embodiments, the content of the inorganic material in the hydrophilic layer is about 90 to 100% by weight (eg, about 95% by weight or more).

In some preferred embodiments, an inorganic oxide such as silicon oxide (typically silicon oxide represented by SiO _x or silicon dioxide represented by SiO ₂ ) is used as the inorganic material. The proportion of the inorganic oxide (typically silicon oxide) in the above-mentioned inorganic material can be set to an appropriate amount to obtain the desired hydrophilic surface, and is not limited to a specific range, for example, approximately 30% by weight. % or more, suitably about 50% by weight or more (for example, more than 50% by weight), and may be about 70% by weight or more. In some preferred embodiments, the proportion of inorganic oxide (typically silicon oxide) in the inorganic material is about 90-100% by weight (eg, about 95% by weight or more).

The method for forming the hydrophilic layer is not particularly limited, and may be formed by any appropriate method depending on the desired thickness. For example, an inorganic material formed into a layer using a known film forming method such as a vacuum evaporation method, a sputtering method, or a plating method can be used as the hydrophilic layer. When using an inorganic compound as the inorganic material, various vapor deposition methods can be used, such as physical vapor deposition (PVD) such as vacuum vapor deposition, sputtering, and ion plating, atomic layer deposition, etc. A chemical vapor deposition method (CVD) or the like can be employed. The coating layer containing an inorganic polymer such as polysiloxane can be formed by appropriately selecting from known coating agents that provide a surface exhibiting a desired water contact angle, and using a conventional method.

<Peeling method>
According to this specification, a method for peeling a pressure-sensitive adhesive sheet stuck to an adherend is provided. This peeling method is suitable as a peeling method for any of the pressure-sensitive adhesive sheets disclosed herein.
In the peeling method, in a state where an aqueous liquid is present at the interface between the adherend and the adhesive sheet at a peeling front of the adhesive sheet from the adherend, the aqueous liquid follows the movement of the peeling front. The method includes a water peeling step of peeling the pressure-sensitive adhesive sheet from the adherend while progressing the water penetration into the interface. Here, the peeling front refers to a point where the adhesive sheet begins to separate from the adherend when the adhesive sheet is peeled from the adherend. According to the water peeling step, the adhesive sheet can be peeled from the adherend by effectively utilizing the aqueous liquid. As the aqueous liquid, water or a mixed solvent containing water as a main component, containing a small amount of additives as necessary, can be used. As the solvent other than water constituting the mixed solvent, lower alcohols (for example, ethyl alcohol), lower ketones (for example, acetone), etc. that can be uniformly mixed with water may be used. As the additive, known surfactants and the like can be used. From the viewpoint of avoiding contamination of the adherend, in some embodiments an aqueous liquid substantially free of additives may be preferably used. From the viewpoint of environmental hygiene, it is particularly preferred to use water as the aqueous liquid. The water is not particularly limited, and for example, distilled water, ion exchange water, tap water, etc. can be used in consideration of the purity and availability required depending on the purpose.

In some embodiments, the peeling method includes supplying an aqueous liquid onto the adherend near the outer edge of the adhesive sheet attached to the adherend, and applying the aqueous liquid from the outer edge of the adhesive sheet to the adhesive sheet. After entering one end of the interface with the adherend, the adhesive sheet is peeled off without supplying new water (i.e., using only the aqueous liquid supplied onto the adherend before starting peeling). This can be preferably carried out in a manner that allows the process to proceed. In some other embodiments, the above peeling method is such that a part of the adhesive sheet attached to the adherend (typically, a part continuous to the outer edge of the adhesive sheet) is lifted from the adherend. This can preferably be carried out in such a manner that an aqueous liquid is supplied to a portion where the remaining adhesive sheet begins to separate from the adherend, and the adhesive sheet is peeled off without supplying new water. In addition, if the water that follows the movement of the peeling front and enters the interface between the adhesive sheet and the adherend runs out during the water peeling process, intermittent or Additional water may be supplied continuously. For example, in cases where the adherend has water absorption properties or where aqueous liquid tends to remain on the adherend surface or adhesive surface after peeling, it is preferable to adopt a mode in which water is additionally supplied after the start of the water peeling process. obtain.

The amount of the aqueous liquid supplied before the start of peeling is not particularly limited as long as it can introduce the aqueous liquid to the interface between the pressure-sensitive adhesive sheet and the adherend. The amount of the aqueous liquid may be, for example, 5 μL or more, usually 10 μL or more is appropriate, and may be 20 μL or more. Further, there is no particular restriction on the upper limit of the amount of the aqueous liquid. In some embodiments, from the viewpoint of improving workability, the amount of the aqueous liquid may be, for example, 10 mL or less, 5 mL or less, 1 mL or less, 0.5 mL or less, 0.1 mL or less. It may be 0.05 mL or less. By reducing the amount of the aqueous liquid, the operation of removing the aqueous liquid by drying, wiping, etc. after peeling off the adhesive sheet can be omitted or simplified.

The operation of injecting an aqueous liquid into the interface between the adhesive sheet and the adherend from the outer edge of the adhesive sheet at the start of peeling can be carried out, for example, by inserting the tip of a jig such as a cutter knife or needle into the interface at the outer edge of the adhesive sheet. Insert the adhesive sheet, scratch the outer edge of the adhesive sheet with a hook or nail, etc., and lift it up, or attach a strong adhesive tape, suction cup, etc. to the back surface near the outer edge of the adhesive sheet and lift the edge of the adhesive sheet. It can be carried out. By forcing the aqueous liquid to enter the interface from the outer edge of the adhesive sheet in this way, it is possible to efficiently create a state in which the aqueous liquid exists at the interface between the adherend and the adhesive sheet. Further, it is desirable to suitably achieve both good water releasability after an operation for forcibly entering an aqueous liquid into an interface to create a trigger for peeling, and high water resistance reliability when such an operation is not performed. I can do it. Note that the above-mentioned operation to trigger peeling is performed on a part of the adhesive sheet attached to the adherend (typically, a part continuous to the outer edge of the adhesive sheet) before supplying the aqueous liquid. It can also be employed as an operation in which the object is suspended above the adherend.

The water stripping process according to some embodiments may be preferably carried out in such a manner that the stripping front is moved at a speed of 10 mm/min or more. Moving the peeling front at a speed of 10 mm/min or more corresponds to peeling the adhesive sheet at a tensile speed of 20 mm/min or more, for example, under the condition of a peeling angle of 180 degrees. The speed at which the peeling front is moved may be, for example, 50 mm/min or more, 150 mm/min or more, 300 mm/min or more, or 500 mm/min or more. According to the peeling method disclosed herein, by peeling the pressure-sensitive adhesive sheet from the adherend while allowing the aqueous liquid to enter the interface, it is possible to achieve good results even at a relatively high peeling speed. It can exhibit excellent water releasability. The upper limit of the speed at which the peeling front is moved is not particularly limited. The speed at which the peeling front is moved may be, for example, 1000 mm/min or less.

The peeling method disclosed herein is carried out in such a manner that the peeling area of the pressure-sensitive adhesive sheet per 10 μL volume of the aqueous liquid (e.g., water) used in the method is, for example, 50 cm ² or more, preferably 100 cm ² or more. be able to.

The peeling method disclosed herein can be preferably applied, for example, to peeling a pressure-sensitive adhesive sheet stuck to a non-water-absorbing smooth surface such as a glass plate, a metal plate, a resin plate, or the like. Moreover, the peeling method disclosed herein can be preferably used as a method for peeling a pressure-sensitive adhesive sheet from any of the above-mentioned optical members. Among these, this method is suitable as a method for peeling adhesive sheets stuck to glass plates such as alkali glass and non-alkali glass.

Hereinafter, some examples relating to the present invention will be described, but the present invention is not intended to be limited to what is shown in these examples. In the following description, "parts" and "%" are based on weight unless otherwise specified.

<Example 1>
(Preparation of adhesive composition)
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, 65 parts of n-butyl acrylate (BA), 6 parts of cyclohexyl acrylate (CHA), and N-vinyl-2-pyrrolidone (NVP) were added as monomer components. 18 parts of isostearyl acrylate (iSTA) and 15 parts of 4-hydroxybutyl acrylate (4HBA), 0.07 parts of α-thioglycerol as a chain transfer agent, 122 parts of ethyl acetate as a polymerization solvent, and a thermal polymerization initiator. A solution containing an acrylic polymer having an Mw of 300,000 was obtained by adding 0.2 part of 2,2'-azobisisobutyronitrile (AIBN) and carrying out solution polymerization in a nitrogen atmosphere.

To the solution obtained above, compound S-1 (3-glycidoxypropyltriethoxysilane, trade name: KBE-403, Shin-Etsu 0.1 part (manufactured by Kagaku Kogyo Co., Ltd.), 0.3 part of nonionic surfactant A (polyoxyethylene sorbitan monolaurate, HLB13.3, trade name: Rheodol TW-L106, manufactured by Kao Corporation) as a water affinity agent. , 0.09 part of isocyanate crosslinking agent (trimethylolpropane/xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Takenate 110N, solid content concentration 75% by mass)) based on solid content, 0.4 part of acrylic oligomer, 0.02 parts of dioctyltin dilaurate (manufactured by Tokyo Fine Chemical Co., Ltd., Envirizer OL-1) as a crosslinking accelerator, 3 parts of acetylacetone as a crosslinking retarder, 3 parts of dipentaerythritol hexaacrylate (DPHA) as a polyfunctional monomer, photopolymerization 0.22 parts of an initiator (manufactured by IGM Regins, trade name: Omnirad 184) was added and mixed uniformly to prepare a solvent-based adhesive composition.

The acrylic oligomer used was one synthesized by the following method.
[Synthesis of acrylic oligomer]
100 parts of toluene, 60 parts of dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Chemical Co., Ltd.), 40 parts of methyl methacrylate (MMA), and 3.5 parts of α-thioglycerol as a chain transfer agent. was added to a four-necked flask. After stirring at 70°C for 1 hour under a nitrogen atmosphere, 0.2 parts of AIBN was added as a thermal polymerization initiator, and the mixture was reacted at 70°C for 2 hours, and then at 80°C for 2 hours. Thereafter, the reaction solution was placed in an atmosphere at a temperature of 130° C., and toluene, a chain transfer agent, and unreacted monomers were removed by drying to obtain a solid acrylic oligomer. This acrylic oligomer had a Tg of 144° C. and a Mw of 4,300.

(Preparation of adhesive sheet)
The adhesive composition obtained above was applied to a 38 μm thick release film R1 (manufactured by Mitsubishi Plastics Co., Ltd., MRF #38) with one side of the polyester film serving as a release surface, and dried at 135° C. for 2 minutes. , an adhesive layer (substrate-less adhesive sheet) with a thickness of 50 μm was formed. The release surface of release film R2 (manufactured by Mitsubishi Plastics Co., Ltd., MRE #38), in which one side of the polyester film is a release surface, was bonded to this adhesive layer for protection. In this way, a laminate sheet was obtained in which the release film R1, the base material-less adhesive sheet, and the release film R2 were laminated in this order.

<Example 2>
As a peel force increasing agent, in place of Compound S-1 used in Example 1, 0.1 part of Compound S-2 (hexadecyltriethoxysilane (manufactured by Tokyo Kasei Kogyo Co., Ltd.)) was used. A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 in other respects, and a pressure-sensitive adhesive sheet according to this example was obtained.

<Example 3>
As a peeling force increasing agent, compound S-3 (3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)) was used instead of compound S-1 used in Example 1. .1 part was used. A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 in other respects, and a pressure-sensitive adhesive sheet according to this example was obtained.

<Example 4>
A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that no peel force increasing agent was used, and a pressure-sensitive adhesive sheet according to this example was obtained.

<Measurement and evaluation>
(1) Water peel force measurement (1-1) Attaching the test piece to the adherend The adhesive layer (substrate-less adhesive sheet) according to each example was cut into a rectangular shape with a width of 20 mm and a length of 120 mm and tested. A piece was prepared. The adhesive side of the above test piece was attached to an alkali glass plate (manufactured by Matsunami Glass Industries Co., Ltd., prepared by the float method, thickness 1.35 mm, polished blue plate edge, contact angle with distilled water: 8 degrees) as an adherend. After bonding with a hand roller and leaving to stand in an environment of 23° C. and 50% RH for 2 hours, light was irradiated through the alkali glass plate in the same environment. The light irradiation was performed from the glass plate side using a high-pressure mercury lamp (manufactured by Toshiba Corporation, trade name H3000L/22N, illuminance 300 mW/cm ² ) under conditions of an integrated light amount of 3000 mJ/cm ² . Thereafter, it was left standing in an environment of 23° C. and 50% RH for 1 hour.

(1-2) Measurement of initial water peeling force (FW0) For the sample obtained in (1-1) above, 3 hours after bonding the test piece to the adherend (i.e. 1 hour after light irradiation) Immediately after), 20 μL of distilled water was supplied onto the adherend, and the distilled water was allowed to enter one end of the interface between the adhesive layer and the base material layer, and then the method was applied in accordance with 10.4 of JIS Z0237:2009. 1 Method 1: According to the 180° peeling adhesive force on the test plate, specifically, the water peeling force FW0 was determined using a tensile tester at a test temperature of 23°C, a tensile speed of 300 mm/min, and a peeling angle of 180 degrees. It was measured. The obtained results are shown in Table 1 in terms of values per 10 mm width.

(1-3) Measurement of water peeling force (FW2) after heat treatment The sample obtained in (1-1) above was held in an environment of 60 °C for 5 hours (heat treatment), and then heated to 23 °C with a 50% After being held in this environment for 1 hour, the water peeling force FW2 was measured in the same manner as the above-mentioned measurement of the initial water peeling force (FW0). The obtained results are shown in Table 1 in terms of values per 10 mm width.

(1-4) Measurement of water peeling force after 3 days, 7 days, and 14 days at room temperature The sample obtained in (1-1) above was kept in an environment of 23°C and 50% RH for 3 days, 7 days, or 14 days. After being allowed to stand still, the water peeling force was measured in the same manner as the above-mentioned measurement of the initial water peeling force (FW0). The obtained results are shown in Table 2 in terms of values per 10 mm width.
The water peeling force of the adhesive sheet of Example 4 was 0.3 N/10 mm after 3 days, 7 days, and 14 days.

(2) Humid heat durability test The adhesive layers (substrate-less adhesive sheets) prepared in Examples 1 to 3 were further subjected to the following moist heat durability test.

(2-1) Preparation of polarizing plate with adhesive layer A 25 μm thick triacetyl cellulose is attached to the viewing side of a polarizer made of a 12 μm thick stretched polyvinyl alcohol film impregnated with iodine using a polyvinyl alcohol adhesive. (TAC) films were bonded together, and a 20 μm thick acrylic film was laminated on the image display side surface of the polarizer using a polyvinyl alcohol adhesive to obtain a polarizing film (P-1). The degree of polarization of the polarizing film was 99.995.
An acrylic adhesive layer A having a thickness of 20 μm was prepared by applying the following acrylic adhesive composition C to the release surface of release film R1 (MRF #38) and drying it. A polarizing plate with an adhesive was produced by laminating this acrylic adhesive layer A to the acrylic film side of the polarizing film (P-1).
[Acrylic adhesive composition C]
A monomer mixture consisting of 98 parts of BA, 1 part of 2-hydroxyethyl acrylate (HEA) and 1 part of acrylic acid (AA) was mixed with 0.3 part of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator. By using ethyl acetate as a polymerization solvent and reacting at 60°C for 4 hours under a nitrogen gas stream, a solution (solid content concentration 30%) containing an acrylic polymer with an Mw of 1.8 million was obtained, and this acrylic polymer Per 100 parts of the solid content of the solution, 0.3 parts of dibenzoyl peroxide (Niper BO-Y, manufactured by NOF Corporation) and 0.02 parts of trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, Coronate L) and 0.1 part of a silane coupling agent (3-glycidoxypropyltrimethoxysilane) were mixed and stirred uniformly to prepare a solvent-type acrylic adhesive composition C. .

(2-2) Preparation of samples for moist heat durability evaluation By laminating the base material-less adhesive sheet (thickness 50 μm) according to each example to the TAC film side of the above adhesive-coated polarizing plate, a photocrosslinkable adhesive layer was formed. A polarizing plate sheet having the following structure was produced.
The above polarizing plate sheet was cut into strips with a width of 40 mm and a length of 70 mm. Next, an alkali glass plate (manufactured by Matsunami Glass Industries Co., Ltd., prepared by the float method, thickness 1.35 mm, polished blue plate edge, contact angle with distilled water: 8 degrees) was cut as described above. A polarizing plate sheet was attached using a hand roller.
Next, the release film R1 covering the acrylic adhesive layer A of the polarizing plate sheet was peeled off, and aluminum foil (manufactured by Mitsubishi Aluminum Foil, trade name "Nipaku Foil", thickness 12 μm) was applied to the exposed acrylic adhesive layer A. I pasted them together using a hand roller and cut them to the same size as the polarizing plate sheet. Thereby, a laminate having a structure of alkali glass plate/adhesive layer/polarizing plate/aluminum foil was obtained.
The laminate was placed in an autoclave and treated for 15 minutes at a pressure of 5 atm and a temperature of 50°C, and then irradiated with light through the alkali glass plate in an environment of 23°C and 50% RH. The above light irradiation was performed by irradiating ultraviolet rays with a cumulative light amount of 3000 mJ/cm ² from the alkali glass side using a high-pressure mercury lamp (300 mW/cm ² ). .

(2-3) Peel strength after moist heat The sample obtained in (2-2) above was held in an environment of 85°C and 85% RH for 24 hours, and then held in an environment of 23°C and 50% RH for 5 hours. I left it still. After that, according to JIS Z0237:2009 10.4.1 Method 1: 180° peeling adhesion force to the test plate, specifically, peeling was performed at a tensile speed of 300 mm/min using a tensile tester at a test temperature of 23°C. Peel strength was measured at an angle of 180 degrees. The obtained results are shown in Table 2 in terms of values per 10 mm width.

(2-4) Humid heat durability evaluation The sample obtained in (2-2) above was held in an environment of 5°C and 85% RH for 500 hours, and then held in an environment of 23°C and 50% RH for 5 hours. I left it still. Thereafter, the presence or absence of peeling and the occurrence of bubbles at the interface between the adhesive layer and the glass plate were visually observed, and the durability was evaluated on the following three levels. The results are shown in Table 2. In addition, when using the pressure-sensitive adhesive sheet according to any of the examples, no air bubbles were observed immediately after the above-mentioned sample for durability evaluation was prepared.
A: Neither peeling nor generation of bubbles was observed.
B: No bubbles were generated, but peeling of less than 3 mm was observed at the edge of the sample.
C: No bubbles were generated, but peeling of 3 mm or more was observed at the edge of the sample.

As shown in Table 1, the pressure-sensitive adhesive sheets of Examples 1 to 4 all had low water peeling forces FW0 and exhibited good water peeling properties at the initial stage of application. In addition, by heat-treating the adhesive sheets of Examples 1 to 3, the water peeling force FW2 could be increased to a greater extent than that of the adhesive sheet of Example 4, and the water resistance reliability could be improved.
Furthermore, among the adhesive sheets of Examples 1 to 3, in which the water peeling force was significantly increased by heat treatment, the adhesive sheets of Examples 1 and 2 were able to retain water for a longer period of time than the adhesive sheet of Example 3, as shown in Table 2. It was possible to suppress the increase in peeling force. Among them, the pressure-sensitive adhesive sheet of Example 1 had high peel strength after moist heat and excellent appearance after moist heat durability test.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above.

1, 2 Adhesive sheet 10 Adhesive layer 10A One surface (adhesive surface)
10B Other surface 20 Base material 20A First surface 20B Second surface (back)
30, 31, 32 Release liner 50 Adhesive sheet with release liner 70 Optical member 100 Member with adhesive sheet

Claims (7)

An adhesive sheet having an adhesive layer,
The adhesive layer contains an acrylic polymer as a base polymer, a peel force increasing agent, a nonionic surfactant as a water affinity agent, an acrylic oligomer, a polyfunctional monomer, and a photopolymerization initiator. including;
The peel force increasing agent has the following general formula (A):
-Si(CH ₃ ) _n (OR) _3-n (A)
(where n is 0 or 1 and R is selected from methyl and ethyl groups);
Comprising a compound S having an alkoxysilyl group represented by and a hydrophobic part in the molecule,
The adhesive layer has an adhesive surface that can be attached to an adherend,
Three hours after pasting the adhesive surface on the alkali glass plate, 20 μL of peeling water is supplied, and the water peeling force FW0 measured at a pulling speed of 300 mm/min and a peeling angle of 180 degrees is 1.0 N/10 mm or less. and,
After the adhesive surface was attached to an alkali glass plate and heat treated at 60°C for 5 hours, water peeling force was measured at room temperature by supplying 20 μL of peeling water at a tensile speed of 300 mm/min and a peel angle of 180 degrees. FW2 is 4.0N/10mm or more,
In the measurement of the water peeling force FW0 and the water peeling force FW2, the adhesive sheet after being attached to the alkali glass is irradiated with light through the alkali glass plate in an environment of 23 ° C. and 50% RH. , adhesive sheet. After pasting the adhesive surface on the alkali glass plate for 7 days at room temperature, 20 μL of peeling water was supplied to obtain a water peeling force FW1 of 1.0 N measured at a pulling speed of 300 mm/min and a peeling angle of 180 degrees. /10 mm or less, where in the measurement of the water peeling force FW1, the adhesive sheet after being attached to the alkali glass is irradiated with light through the alkali glass plate in an environment of 23 ° C. and 50% RH. The adhesive sheet according to claim 1 , which performs the following . The adhesive sheet according to claim 1 or 2 , wherein the adhesive layer contains, as the compound S, a compound having an ethoxysilyl group. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the pressure-sensitive adhesive layer is a layer formed from a photocurable or solvent-type pressure-sensitive adhesive composition. The adhesive surface was attached to an alkali glass plate and held in a moist heat environment of 85°C and 85% RH for 24 hours, then held in an environment of 23°C and 50% RH for 5 hours, and then stretched at a tensile speed of 300 mm in the same environment. /min, peel strength after moist heat FN1 measured under the conditions of 180 degrees of peeling angle is 3.0 N/10 mm or more, where in the measurement of the peel strength after moist heat FN1, the adhesive after pasting on the alkali glass The adhesive sheet according to any one of claims 1 to 4 , wherein the sheet is irradiated with light through the alkali glass plate in an environment of 23° C. and 50% RH . A laminate including a member and an adhesive sheet layer laminated on the member,
The laminate, wherein the adhesive sheet layer is a layer formed by laminating the adhesive sheet according to any one of claims 1 to 5 to the member. 7. The laminate according to claim 6 , wherein the member has a surface to which the pressure-sensitive adhesive sheet is attached having a contact angle with respect to distilled water of 50 degrees or less.

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