JP6188380B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive sheet, and particularly relates to a thin film single-sided pressure-sensitive adhesive sheet or double-sided pressure-sensitive adhesive sheet.

  In recent years, various mobile electronic devices typified by game machines and mobile phones have been improved in functionality, and devices have been made lighter, thinner and smaller. Accordingly, each member used in the mobile electronic device is required to have high functionality, lightness, and miniaturization.

  In the assembly of the mobile electronic device as described above, a pressure-sensitive adhesive sheet such as a double-sided tape may be used, and the use of the pressure-sensitive adhesive sheet can simplify the assembly process and reduce the thickness of the device. As for the total thickness of such an adhesive sheet, about 40-200 micrometers is common. However, even the thickness of the pressure-sensitive adhesive sheet cannot be ignored due to the miniaturization of mobile electronic devices, and recently, a pressure-sensitive adhesive sheet having a total thickness of 30 μm or less is often demanded.

  For example, Patent Document 1 discloses a thin-film double-sided adhesive tape. Specifically, it has a pressure-sensitive adhesive layer made of an acrylic or silicone pressure-sensitive adhesive on both sides of a support made of a polyester film, and is supported. The body thickness is 0.002 to 0.004 mm, and the total thickness including the thickness of the support and the two adhesive layers formed on both sides of the support is 0.003 mm or more and less than 0.03 mm Also disclosed is a double-sided adhesive tape having a breaking strength of 2 to 26 MPa / 10 mm width.

  In the above double-sided adhesive tape, in order to protect the adhesive surface of the adhesive layer, a release sheet having a release agent layer formed on one side of a release substrate such as a plastic film by a release treatment is provided.

Japanese Patent No. 4646508

  By the way, when the thickness of an adhesive sheet will be 20 micrometers or less as mentioned above, a peeling sheet will become difficult to peel from an adhesive layer. Therefore, a separate adhesive tape is prepared, and after the adhesive tape is attached to the end of the release sheet opposite to the release agent layer (non-release treatment surface), the release adhesive tape is lifted. Thus, it is considered effective to create a trigger for peeling and peel the release sheet. However, depending on the type of the release agent layer, the adhesiveness of the non-peeled surface of the release sheet to the peelable adhesive tape is low, and when the peelable adhesive tape is lifted, the peelable adhesive tape is detached from the non-peeled treated surface. Therefore, the release sheet may not be peeled off.

  In addition, for the purpose of positioning when the pressure-sensitive adhesive sheet is bonded to the adherend, it is conceivable to perform marking with an oil-based pen on the surface of the pressure-sensitive adhesive sheet on the side of the release sheet (the non-peeled surface of the release sheet). In this case, oil-based ink adhesion is required for the non-peeling surface of the release sheet. However, similar to the above, depending on the type of the release agent layer, the oil-based ink may be repelled and marking may not be possible.

  This invention is made | formed in view of such an actual condition, and it aims at providing the adhesive sheet excellent in the adhesiveness with respect to the adhesive tape for peeling in the non-peeling process surface of a peeling sheet, and oil-based ink adhesiveness. .

  In order to achieve the above object, the present invention provides a base material, a pressure-sensitive adhesive layer laminated on one or both sides of the base material, and a release laminated on the surface of the pressure-sensitive adhesive layer opposite to the base material. The pressure-sensitive adhesive sheet has a thickness of 1 to 16 μm, the thickness of the base material is 1 to 16 μm, and the thickness of the pressure-sensitive adhesive sheet excluding the release sheet. Is 2 to 20 μm, and the release sheet is composed of a release substrate and a release agent layer formed on one side of the release substrate, and the release agent layer contains a silicone compound. The pressure-sensitive adhesive sheet is characterized in that the amount of silicone on the surface of the release sheet opposite to the release agent layer is 4% or less (Invention 1).

  In the pressure-sensitive adhesive sheet according to the invention (Invention 1), the amount of silicone on the surface opposite to the release agent layer (non-release treatment surface) of the release sheet is defined as described above, whereby the release on the non-release treatment surface. Excellent adhesion to adhesive tape and oil-based ink adhesion.

  In the said invention (invention 1), it is preferable that the said peeling base material is comprised from a plastic film (invention 2).

  In the said invention (invention 2), it is preferable that the said plastic film which comprises the said peeling base material is a polyethylene terephthalate film (invention 3).

  In the said invention (invention 1-3), it is preferable that the thickness of the said peeling base material is 12-75 micrometers (invention 4).

  In the said invention (invention 1-4), it is preferable that the thickness of the said releasing agent layer is 0.01-2 micrometers (invention 5).

  In the said invention (invention 1-5), it is preferable that the peeling force of the said peeling sheet is 10-200 mN / 25mm (invention 6).

  According to the present invention, since the non-peeling surface of the release sheet to be used is excellent in adhesiveness to the adhesive tape for peeling and excellent in oil-based ink adhesion, it is possible to provide a thin film adhesive sheet with excellent handling properties. it can.

It is sectional drawing of the adhesive sheet which concerns on the 1st Embodiment of this invention. It is sectional drawing of the adhesive sheet which concerns on the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[First Embodiment]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 </ b> A according to the first embodiment of the present invention has a release sheet 4, a pressure-sensitive adhesive layer 3 laminated on the release surface of the release sheet 4, and a release of the pressure-sensitive adhesive layer 3. It is a so-called single-sided pressure-sensitive adhesive sheet composed of a base material 2A laminated on the side opposite to the sheet 4 side (upper side in FIG. 1). Note that the release surface of the release sheet in this specification refers to a surface having release properties (a surface subjected to release treatment) in the release sheet. On the other hand, the surface opposite to the release agent layer of the release sheet in this specification refers to the surface (non-release treatment surface) of the release substrate that does not contact the release agent layer.

  The pressure-sensitive adhesive sheet 1A according to this embodiment is a thin-film pressure-sensitive adhesive sheet. Specifically, the thickness of the pressure-sensitive adhesive layer 3 is 1 to 16 μm, the thickness of the base material 2A is 1 to 16 μm, and the thickness of the pressure-sensitive adhesive sheet 1A excluding the release sheet 4 (the pressure-sensitive adhesive layer 3 and the base layer). The total thickness of the material 2A is 2 to 20 μm. When each part of the pressure-sensitive adhesive sheet 1A has such a thickness, the pressure-sensitive adhesive sheet 1A is suitable for use in, for example, a thin mobile electronic device.

  The release sheet 4 in the present embodiment includes a release substrate 401 and a release agent layer 402 formed on one side of the release substrate 401 by a release process. By forming the release agent layer 402 on the release substrate 401 in this way, the release force of the release sheet 4 is reduced, and the thin adhesive layer 3 is prevented from being deformed or broken when the release sheet 4 is released. Can do.

  The release agent layer 402 in this embodiment contains a silicone compound. That is, the release agent constituting the release agent layer 402 in the present embodiment is a silicone release agent. Silicone release agents are cheaper and can stably achieve lower release forces than other release agents.

  The silicone amount of the surface opposite to the release agent layer 402 in the release sheet 4 (non-release treatment surface; reference numeral 40) is 4% or less, preferably 0.5 to 3.8%, particularly preferably. 0.5 to 3.5%. When the release sheet 4 is manufactured and wound up, the release agent layer 402 and the non-release treatment surface 40 come into contact with each other. At this time, the silicone compound contained in the release agent layer 402 is non-release treatment surface. 40. As a result, silicone is detected on the non-peeling surface 40. When the amount of silicone is 4% or less, the adhesiveness of the non-peeling treatment surface 40 to the peeling pressure-sensitive adhesive tape is excellent. Accordingly, when the release sheet 4 is peeled from the pressure-sensitive adhesive sheet 1A (pressure-sensitive adhesive layer 3), a peeling adhesive tape is applied to the non-peeling treatment surface 40, and the peeling adhesive tape is lifted to create a trigger for peeling. In addition, the release adhesive tape is prevented from being detached from the release sheet 4, and the release sheet 4 can be smoothly released by the release adhesive tape. Further, when the amount of silicone is 4% or less, the non-peeled surface 40 is excellent in oil-based ink adhesion. Therefore, even when marking the non-peeling surface 40 with an oil pen, the oil ink is prevented from being repelled and marking can be performed without any problem. When the amount of silicone exceeds 4%, the adhesiveness of the non-peeling surface 40 to the peeling adhesive tape is lowered, and the peeling adhesive tape cannot be used as described above, and the peeling sheet 4 is poorly peeled. It becomes. Moreover, the oil-based ink adhesion of the non-peeling surface 40 is lowered, and the oil-based ink is repelled. The silicone amount may be reduced by densely crosslinking the release agent layer 402 or by reducing the temperature and time of heat drying when forming the adhesive layer 3 on the release sheet 4. it can.

  On the other hand, the lower limit value of the silicone amount is preferably 0.5% or more. If the amount of silicone is to be less than 0.5%, it is necessary to increase the crosslink density of the silicone compound in the release agent layer 402, and thereby the release force of the release sheet 4 becomes too high, and the thin film is peeled off. The adhesive layer 3 may be deformed.

Here, the amount of silicone (%) in this specification is the silicon atom (Si), carbon atom (C), and oxygen atom (O) measured by X-ray photoelectron analysis (XPS) on the non-peeled surface 40. % Based on the amount of A calculated by the following formula.
Silicone amount (%) = {Si / (Si + C + O)} × 100
That is, the atoms detected by XPS on the non-peeled surface 40 are approximately 100% of silicon, carbon and oxygen, so the silicon content in these atoms is the amount of silicone as described above. In most cases, the release substrate itself is at a level at which silicon is not detected by XPS, and therefore the silicone amount can be used as an evaluation standard for the transfer amount of the release agent (silicone compound) in the release agent layer. it can.

  The silicone release agent contains a silicone compound such as polyorganosiloxane. A typical example of polyorganosiloxane is polydimethylsiloxane. The polyorganosiloxane may have no reactive functional group or may have a reactive functional group, but in order to keep the amount of silicone low, the reactive functional group may be reduced. What has is preferable. By using this, it is possible to crosslink the polyorganosiloxane at the time of forming the release agent layer 402 to reduce the amount of low molecular weight polyorganosiloxane present in the release agent layer 402, thereby reducing the amount of silicone. it can.

  The thickness of the release agent layer 402 is preferably 0.01 to 2 μm, particularly preferably 0.01 to 1 μm, and more preferably 0.01 to 0.5 μm. If the thickness of the release agent layer 402 is less than 0.01 μm, the function as the release agent layer 402 may not be sufficiently exerted depending on the material constituting the release agent layer 402 or the like. On the other hand, when the thickness of the release agent layer 402 exceeds 2 μm, blocking tends to occur when the release sheet 4 is wound up alone, and there is a possibility that a problem may occur when the pressure-sensitive adhesive layer 3 is formed.

  It is preferable that the peeling base material 401 is comprised from a plastic film. By forming the release substrate 401 from a plastic film, the surface of the release agent layer 402 opposite to the release substrate 401, that is, the release surface of the release sheet 4 is flattened, and the pressure-sensitive adhesive is in contact with the release surface. The adhesive surface of the layer 3 can also be made flat. Thereby, the contact area of an adhesion surface and a to-be-adhered body can be increased, and adhesive force can be raised.

  Examples of the plastic film constituting the release substrate 401 include, for example, a polyester film made of polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, a polyolefin film made of polyolefin such as polyethylene, polypropylene, and polymethylpentene, a polycarbonate film, Examples thereof include plastic films such as polyvinyl acetate film; and laminates of two or more of these. Among these, from the viewpoints of thickness accuracy, surface smoothness, availability, and the like, a polyester film is preferable, and a polyethylene terephthalate film is particularly preferable.

  In the peeling substrate 401 made of the plastic film as described above, for example, an oxidation method or a concavo-convex method on one side or both sides as desired for the purpose of improving the adhesion with the release agent layer 402 provided on the surface. The surface treatment or primer treatment can be performed. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like. Examples include a thermal spraying method. These surface treatment methods are appropriately selected according to the type of the plastic film, but in general, the corona discharge treatment method is preferably used from the viewpoints of effects and operability.

  The thickness of the release substrate 401 is preferably 12 to 75 μm, particularly preferably 25 to 50 μm, and more preferably 25 to 38 μm. If the thickness of the release substrate 401 is less than 12 μm, thermal shrinkage that occurs during the drying process for forming the release agent layer 402 or the pressure-sensitive adhesive layer 3 is increased, which may cause problems such as wrinkles. . On the other hand, when the thickness of the release substrate 401 exceeds 75 μm, the adhesive sheet 1A (laminated body of the base material 2A and the adhesive layer 3) follows the release sheet 4 when the release sheet 4 is released, and is low. Even if it is peeling force, there exists a possibility that it may become difficult to peel.

  The peeling force of the release sheet 4 with respect to the pressure-sensitive adhesive layer 3 (peeling force according to ISO 8510-2: 1990) is preferably 10 to 200 mN / 25 mm, particularly preferably 10 to 150 mN / 25 mm, Is preferably 10 to 100 mN / 25 mm. When the peeling force is less than 10 mN / 25 mm, the release sheet 4 may float from the pressure-sensitive adhesive layer 3 when an impact is applied to the pressure-sensitive adhesive sheet 1A from the outside. On the other hand, when the peeling force exceeds 200 mN / 25 mm, the peeling force of the release sheet 4 is too high, and the adhesive layer 3 of the thin film may be deformed at the time of peeling, and peeling with the peeling adhesive tape becomes difficult. There is a fear.

  The substrate 2A in the present embodiment is preferably composed of a plastic film. According to the plastic film, it is relatively easy to set the thickness of the base material 2A within the above-described range. Examples of the plastic film include polyester films made of polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyurethane films, polyethylene films, polypropylene films, cellulose films such as triacetyl cellulose, polyvinyl chloride films, poly Plastic films such as vinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene resin film, cycloolefin resin film; laminates of two or more of these Can be mentioned. The plastic film may be uniaxially stretched or biaxially stretched. Among these, a polyester film is preferable and a polyethylene terephthalate film is particularly preferable from the viewpoints of thickness accuracy, surface smoothness, availability, and the like required as the film is thinned.

  Also for the base material 2A, for the purpose of improving the adhesiveness with the adjacent pressure-sensitive adhesive layer 3 or the like, a surface treatment by an oxidation method, a concavo-convex method or the like is applied to one side or both sides as desired, similarly to the peeling base material 401. Alternatively, primer treatment can be performed.

  As described above, the thickness of the base 2A is 1 to 16 μm, preferably 2 to 12 μm, and particularly preferably 2 to 6 μm. When the thickness of the base material 2A exceeds 16 μm, it is difficult to make the thickness of the pressure-sensitive adhesive sheet 1A excluding the release sheet 4 20 μm or less, which satisfies the required performance as a pressure-sensitive adhesive sheet used for thin mobile electronic devices and the like. become unable. On the other hand, if the thickness of the base material 2A is less than 1 μm, sufficient strength cannot be obtained, and there is a possibility of breaking during processing.

  The type of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3 is not particularly limited as long as a desired adhesive strength can be obtained with a thin film, and is an acrylic pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyurethane-based pressure-sensitive adhesive. Any of rubber adhesives and the like may be used. The pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, and may be a crosslinked type or a non-crosslinked type. As an adhesive which comprises the adhesive layer 3, an acrylic adhesive is preferable among the above. The acrylic pressure-sensitive adhesive easily exhibits a desired adhesive force even in a thin film, and has good releasability from the release sheet 4 having the release agent layer 402 containing a silicone compound. Further, from the viewpoint of obtaining the thin-film pressure-sensitive adhesive layer 3, the pressure-sensitive adhesive is preferably a solvent-type pressure-sensitive adhesive.

  The acrylic pressure-sensitive adhesive is preferably a cross-linked type having a high film strength even in a thin film. Specifically, the acrylic pressure-sensitive adhesive is obtained by cross-linking a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester polymer and a cross-linking agent. Is preferred. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

  The (meth) acrylic acid ester polymer preferably has a reactive group capable of reacting with the crosslinking agent. Examples of the reactive group include a hydroxyl group, a carboxyl group, an amino group, and the like, and among them, a hydroxyl group or a carboxyl group is preferable. That is, the (meth) acrylic acid ester polymer preferably contains a monomer having a hydroxyl group (hydroxyl group-containing monomer) or a monomer having a carboxyl group (carboxyl group-containing monomer) as a monomer unit constituting the polymer.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. These may be used alone or in combination of two or more.

  Preferred examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer preferably contains 0.1 to 20% by mass, particularly 1 to 10% by mass, of a hydroxyl group-containing monomer or a carboxyl group-containing monomer as a monomer unit constituting the polymer. It is preferable to contain 5-10 mass%.

  When the content of the hydroxyl group-containing monomer or the carboxyl group-containing monomer is in the above range, the cross-linked structure to be formed becomes favorable, and the resulting adhesive can maintain high film strength even in a thin film.

  The (meth) acrylic acid ester polymer preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer, particularly as a main component. It is preferable. Thereby, the obtained adhesive can express preferable adhesiveness.

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the tackiness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferred, methyl (meth) acrylate, n-butyl (meth) acrylate and (meth) acrylic. The acid 2-ethylhexyl is particularly preferred. In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer preferably contains 10 to 99.9% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. In particular, the content is preferably 30 to 99% by mass, and more preferably 80 to 99% by mass.

  The (meth) acrylic acid ester polymer may contain other monomers as a monomer unit constituting the polymer, if desired.

  A random copolymer may be sufficient as the superposition | polymerization aspect of a (meth) acrylic acid ester polymer, and a block copolymer may be sufficient as it.

  The weight average molecular weight of the (meth) acrylic acid ester polymer is preferably 300,000 to 2,000,000, particularly preferably 500,000 to 1,500,000, and more preferably 500,000 to 900,000. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  The crosslinking agent may be any one that reacts with the reactive group of the (meth) acrylic acid ester polymer. For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an amine crosslinking agent, a melamine crosslinking agent, an aziridine -Based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. An isocyanate-based crosslinking agent that is excellent in reactivity with a carboxyl group is preferred. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. And biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with a low-molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, and the like. Among these, trimethylolpropane-modified aromatic polyisocyanate, especially from the point of reactivity with the reactive group of (meth) acrylic acid ester polymer, Trimethylolpropane-modified xylylene diisocyanate and trimethylolpropane-modified tolylene diisocyanate is preferable.

  It is preferable that the compounding quantity of a crosslinking agent is 0.01-10 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymers, and it is especially preferable that it is 0.1-5 mass parts. When the blending amount of the crosslinking agent is in the above range, the gel fraction of the pressure-sensitive adhesive described later can be easily controlled within a preferable range, and the durability of the pressure-sensitive adhesive can be improved.

  The above-mentioned pressure-sensitive adhesive composition can be prepared by adding various additives usually used for acrylic pressure-sensitive adhesives, for example, rosin-based, methylstyrene-based, terpene-based tackifiers, silane coupling agents, antistatic agents, oxidation agents, and the like. You may contain an inhibitor, a ultraviolet absorber, a light stabilizer, a softener, a filler, a refractive index regulator, a dye, a pigment, a rust preventive agent, etc.

  As described above, the thickness of the pressure-sensitive adhesive layer 3 is 1 to 16 μm, preferably 2 to 12 μm, and particularly preferably 2 to 6 μm. When the thickness of the pressure-sensitive adhesive layer 3 exceeds 16 μm, it is difficult to make the thickness of the pressure-sensitive adhesive sheet 1A excluding the release sheet 4 20 μm or less, and satisfy the required performance as a pressure-sensitive adhesive sheet used for thin mobile electronic devices and the like. Can not be. On the other hand, when the thickness of the pressure-sensitive adhesive layer 3 is less than 1 μm, it is impossible to follow the surface unevenness of the adherend, and the necessary adhesive force cannot be obtained.

  The gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3 is preferably 20 to 100%, particularly preferably 30 to 90%, and further preferably 40 to 80%. When the gel fraction is the above value, the pressure-sensitive adhesive layer 3 exhibits good durability. If the gel fraction is less than 20%, the pressure-sensitive adhesive layer 3 may be deformed or foamed under heating conditions or the like. In addition, the said gel fraction is a value about the adhesive formed after the curing period passed (for example, after storing in 23 degreeC and 50% RH environment for 7 days). If it is unclear whether the curing period has elapsed, after storing again for 7 days in an environment of 23 ° C. and 50% RH, the gel fraction should be within the above range.

  The storage elastic modulus (G ′) at 25 ° C. of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3 is preferably 0.03 to 0.3 MPa, particularly preferably 0.03 to 0.25 MPa. Is preferably 0.03 to 0.2 MPa. If the storage elastic modulus is less than 0.03 MPa, the adhesive may ooze out from the edge of the adhesive sheet 1A. On the other hand, when the storage elastic modulus exceeds 0.3 MPa, the pressure-sensitive adhesive layer 3 cannot follow the surface irregularities of the adherend, and the adhesive force may be reduced. The storage elastic modulus (G ′) is a value measured by a torsional shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6.

  The pressure-sensitive adhesive sheet 1A preferably has an adhesive strength to an alkali-free glass of 4 N / 25 mm or more, particularly preferably 4.7 N / 25 mm or more, and more preferably 5 N / 25 mm or more. When the adhesive strength is within the above range, good adhesiveness can be obtained with an adherend such as a glass plate, and floating or peeling can be prevented.

  The adhesive strength here means basically the adhesive strength measured by the 180 ° peeling method according to JIS Z0237: 2009. The measurement sample has a width of 25 mm and a length of 250 mm and uses a 2 kg rubber roller. After the measurement sample is attached to the adherend, the sample is allowed to stand for 24 hours under conditions of normal pressure, 23 ° C., and 50% RH, and then measured at a peeling rate of 300 mm / min.

  As one manufacturing example of the pressure-sensitive adhesive sheet 1A, a solution (coating solution) containing a pressure-sensitive adhesive composition is applied to the release surface of the release sheet 4, and heat treatment is performed to form a coating layer. The substrate 2A is laminated. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 3 as it is. Thereby, the said adhesive sheet 1A is obtained.

  When the pressure-sensitive adhesive is a crosslinked type, the pressure-sensitive adhesive is obtained by crosslinking the pressure-sensitive adhesive composition. Cross-linking of the pressure-sensitive adhesive composition can be performed by heat treatment. This heat treatment can also serve as a drying treatment when the diluting solvent of the adhesive composition is volatilized.

  When performing heat processing, it is preferable that heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes. Furthermore, it is particularly preferable to provide a curing period of about 1 to 2 weeks at room temperature (for example, 23 ° C., 50% RH) after the heat treatment.

  In order to use the pressure-sensitive adhesive sheet 1 </ b> A according to the present embodiment, a pressure-sensitive adhesive tape for peeling is affixed to an end portion, preferably a corner portion, of the non-peeled surface 40 of the release sheet 4. Then, while supporting the base material 2A of the adhesive sheet 1A, the release adhesive tape is lifted while curving, and the release sheet 4 is peeled from the adhesive layer 3 of the adhesive sheet 1A. At this time, since the non-peeling treatment surface 40 of the release sheet 4 is excellent in adhesiveness to the peeling adhesive tape, it is prevented that the peeling adhesive tape is detached from the non-peeling treatment surface 40, and the release sheet 4 is made smooth. Can be peeled off. Then, 1 A of adhesive sheets and a to-be-adhered body are bonded through the exposed adhesive layer 3. FIG.

  Although it does not specifically limit as said adhesive tape for peeling, The thing using an acrylic adhesive is preferable. Examples of commercially available products include polyester adhesive tape No. 1 manufactured by Nitto Denko Corporation. 31B or the like can be used.

  Further, in the pressure-sensitive adhesive sheet 1A according to the present embodiment, the non-peeled surface 40 of the release sheet 4 is excellent in oil-based ink adhesion. Therefore, even if an oil-based pen is used for the non-peeled surface 40, the oil-based ink is not elastic. It is possible to mark without any problem.

[Second Embodiment]
As shown in FIG. 2, the pressure-sensitive adhesive sheet 1 </ b> B according to the second embodiment of the present invention is a base material 2 </ b> B and a first pressure-sensitive adhesive layered on one surface (the upper surface in FIG. 2). The first release sheet 41 laminated on the side opposite to the base material 2B (upper side in FIG. 2) in the first adhesive layer 31, and the other side of the base material 2B (lower side in FIG. 2) The second adhesive sheet 32 laminated on the side surface), and the second release sheet 42 laminated on the opposite side (lower side in FIG. 2) of the base material 2B in the second adhesive layer 32; Consists of The pressure-sensitive adhesive sheet 1 </ b> B in the present embodiment is a so-called double-sided pressure-sensitive adhesive sheet, and the base material 2 </ b> B is a support base material that supports the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32.

  The first release sheet 41 includes a release substrate 411 and a release agent layer 412 formed on one side of the release substrate 411. The second release sheet 42 includes the release substrate 421 and the release substrate. It is composed of a release agent layer 422 formed on one surface of the substrate 421. The first release sheet 41 is laminated on the first adhesive layer 31 so that the release agent layer 412 is in contact with the first adhesive layer 31, and the second release sheet 42 is the release agent layer. 422 is laminated on the second pressure-sensitive adhesive layer 32 so as to be in contact with the second pressure-sensitive adhesive layer 32.

  The adhesive sheet 1B according to the present embodiment is also a thin film adhesive sheet. Specifically, the thickness of the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32 is 1 to 16 μm, the thickness of the substrate 2B is 1 to 16 μm, and the first release sheet 41 The thickness of the pressure-sensitive adhesive sheet 1B excluding the second release sheet 42 (the total thickness of the first pressure-sensitive adhesive layer 31, the second pressure-sensitive adhesive layer 32, and the base material 2B) is 3 to 20 μm. When each part of the pressure-sensitive adhesive sheet 1B has such a thickness, the pressure-sensitive adhesive sheet 1B is suitable for use in, for example, a thin mobile electronic device.

  The material and physical properties of the base material 2B are the same as those of the base material 2A of the pressure-sensitive adhesive sheet 1A according to the first embodiment, and the materials and physical properties of the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32 are: This is the same as the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1A according to the first embodiment.

  The materials and physical properties of the first release sheet 41 and the second release sheet 42 are the same as those of the release sheet 4 of the pressure-sensitive adhesive sheet 1A according to the first embodiment. However, it is preferable to provide a difference in peel force between the first release sheet 41 and the second release sheet 42, and one (for example, the first release sheet 41) is a light release release sheet having a small peel force, The other (for example, the second release sheet 42) is preferably a heavy release type release sheet having a high release force. Specifically, the first release sheet 41 and the second release sheet 42 preferably have a peel force difference of 5 mN / 25 mm or more, and have a peel force difference of 10 mN / 25 mm or more. It is particularly preferable. This is because, by having the above-described difference in peel force, the release sheet that is peeled first can be easily removed without damaging the surface of the pressure-sensitive adhesive layer.

  Also in the pressure-sensitive adhesive sheet 1B according to the present embodiment, the silicone amount of the non-peeling treated surface 40 of the first release sheet 41 and the non-peeling treated surface 40 of the second release sheet 42 is 4% or less, preferably 0. 0.5 to 3.8%, particularly preferably 0.5 to 3.5%. Thereby, the adhesiveness with respect to the peeling adhesive tape of the non-peeling process surface 40 in the 1st peeling sheet 41 and the 2nd peeling sheet 42 becomes excellent, and the adhesive sheet 1B (the 1st adhesive layer 31 or the 2nd When the first release sheet 41 or the second release sheet 42 is peeled from the pressure-sensitive adhesive layer 32), the first release sheet 41 or the second release sheet 42 is smoothly peeled off using the peeling adhesive tape. Can do. In addition, the oil-based ink adhesion on the non-peeled treated surface 40 of the first release sheet 41 and the second release sheet 42 becomes excellent, preventing the oil-based ink from being repelled, and marking with an oil-based pen is a problem. Can be done without.

  As an example of production of the pressure-sensitive adhesive sheet 1B, a solution (coating solution) containing a pressure-sensitive adhesive composition is applied to the release surface of the first release sheet 41, and heat treatment is performed to form a coating layer. The base material 2B is laminated on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the first pressure-sensitive adhesive layer 31 as it is. In this way, a first laminate is obtained. On the other hand, a solution (coating solution) containing the adhesive composition is applied to the release surface of the second release sheet 42, and heat treatment is performed to form an application layer. When a curing period is required, a curing period is set. When the curing period is not necessary, the coating layer becomes the second pressure-sensitive adhesive layer 32 as it is. In this way, a second laminate is obtained. Then, the first laminate and the second laminate are bonded together so that the base material 2B of the first laminate and the second adhesive layer 32 of the second laminate are overlapped, and the adhesive Sheet 1B is obtained. In addition, in the adhesive layer (31 and 32) formation stage on the release sheets (41 and 42), the substrate 2B is laminated without taking a curing period, and the first adhesive layer 31 and The said adhesive sheet 1B can also be obtained by taking the curing period match | combined with the longer one of the 2nd adhesive layer 32. FIG.

  In order to use the pressure-sensitive adhesive sheet 1B according to the present embodiment, as an example, the first release sheet 41 (preferably a light release type release sheet) is peeled at an end portion, preferably a corner portion, of the non-peeled treatment surface 40. Apply adhesive tape. Then, while supporting the second release sheet 42 (preferably a heavy release type release sheet), the release adhesive tape is lifted while being bent, and the first release from the first adhesive layer 31 of the adhesive sheet 1B. The sheet 41 is peeled off. Thereafter, the pressure-sensitive adhesive sheet 1B and the first adherend are bonded through the exposed first pressure-sensitive adhesive layer 31. Next, a peeling adhesive tape is affixed to an end portion, preferably a corner portion, of the non-peeling treatment surface 40 of the second release sheet 42. Then, while supporting the adherend, the second peeling sheet 42 is peeled from the second pressure-sensitive adhesive layer 32 of the pressure-sensitive adhesive sheet 1B by lifting the peeling pressure-sensitive adhesive tape while curving it. Then, the adhesive sheet 1B and the second adherend are bonded through the exposed second adhesive layer 32. Since the non-peeling surface 40 of the release sheet 4 is excellent in the adhesive property of the peelable adhesive tape, the peelable adhesive tape is not peeled off in the peeling step of the first release sheet 41 and the second release sheet 42 described above. Detachment from the surface 40 is prevented, and the first release sheet 41 and the second release sheet 42 can be smoothly released.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, on the surface opposite to the pressure-sensitive adhesive layer 3 in the base material 2A of the pressure-sensitive adhesive sheet 1A, a functional layer such as a hard coat layer, an easy-adhesion layer, a reflective layer, an antiglare layer, a conductive film, a print layer, a print Other layers such as a decorative layer such as a layer or a paint coating film may be laminated.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of (meth) acrylic acid ester polymer In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introduction tube, 90 parts by mass of n-butyl acrylate, 10 parts by mass of acrylic acid, 200 ethyl acetate Part by mass and 0.15 part by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 16 hours, and then cooled to room temperature. Here, the molecular weight of a part of the obtained solution was measured by the method described later, and production of a (meth) acrylic acid ester polymer having a weight average molecular weight (Mw) of 600,000 was confirmed.

2. Preparation of adhesive composition 100 parts by mass (solid content converted value; the same applies hereinafter) of the (meth) acrylic acid ester polymer (A) obtained in the above step (1) and a crosslinking agent (isocyanate-based crosslinking agent) By mixing 0.15 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate L), stirring sufficiently, and diluting with methyl ethyl ketone, an adhesive composition having a nonvolatile content concentration of 15% by mass A coating solution was obtained.

3. Manufacture of pressure-sensitive adhesive sheet A release sheet in which a release layer is formed with a silicone release agent on one side of a polyethylene terephthalate film, which is a release substrate (RLTEC, release substrate thickness: 38 μm, release agent layer After coating the adhesive composition coating solution on the surface of the release agent layer (peeling surface) (thickness: 0.1 μm, total thickness: about 38 μm) with a knife coater so that the thickness after drying becomes 2 μm. Then, a coating layer was formed by heat treatment at 90 ° C. for 1 minute.

  Next, a polyethylene terephthalate film (manufactured by Mitsubishi Plastics, K100-2.0W, thickness: 2 μm) as a base material is bonded to the exposed surface side of the coating layer, and under conditions of 23 ° C. and 50% RH. By curing for 7 days, a pressure-sensitive adhesive sheet having a structure of base material (thickness: 2 μm) / pressure-sensitive adhesive layer (thickness: 2 μm) / release sheet (thickness: 38 μm) was produced.

[Example 2]
As a release sheet, another release sheet in which a release agent layer is formed with a silicone release agent on one side of a polyethylene terephthalate film which is a release substrate (RLTECH, RL-2, release substrate thickness: 38 μm, release agent) A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the layer thickness was 0.1 μm and the total thickness was about 38 μm.

Example 3
As a release sheet, another release sheet in which a release agent layer is formed with a silicone release agent on one side of a polyethylene terephthalate film as a release substrate (RLTEC, release substrate thickness: 38 μm, release agent) A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the layer thickness was 0.1 μm and the total thickness was about 38 μm.

Example 4
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, except that the thickness of the pressure-sensitive adhesive layer was 4 μm, and another polyethylene terephthalate film (Embret PET, thickness: 12 μm) was used as the base material.

Example 5
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the amount of the crosslinking agent in the pressure-sensitive adhesive composition was changed to 0.03 parts by mass.

[Comparative Example 1]
As a release sheet, another release sheet having a release agent layer formed of a silicone release agent on one side of a polyethylene terephthalate film as a release substrate (RLTEC, RL-4, release substrate thickness: 38 μm, release agent A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the layer thickness was 0.1 μm and the total thickness was about 38 μm.

[Comparative Example 2]
As a release sheet, another release sheet having a release agent layer formed with a silicone release agent on one side of a polyethylene terephthalate film as a release substrate (manufactured by Lintec, RL-6, thickness of release substrate: 38 μm, release agent A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the layer thickness was 0.1 μm and the total thickness was about 38 μm.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of silicone content)
The pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was cut to prepare samples having a width of 10 mm and a length of 10 mm. The silicone amount (%) of the non-peeled surface of the release sheet in this sample was measured and calculated by X-ray photoelectron analysis (XPS). As a measuring device, Quantara SXM manufactured by ULVAC-PHI was used, and the measurement conditions were as follows.
X-ray: AlKα (1486.6 eV)
Extraction angle: 45 °
Measurement elements: silicon atom (Si), carbon atom (C), oxygen atom (O)

The silicone amount (%) is calculated based on the following formula. The results are shown in Table 1.
Silicone amount (%) = {Si / (Si + C + O)} × 100

  In addition, although the amount of silicone (%) of the polyethylene terephthalate film (release substrate) itself before forming the release agent layer was measured in the same manner, it was 0%. That is, the amount of silicone has a correlation with the transfer of the release agent (silicone compound) in the release agent layer.

[Test Example 2] (Evaluation of peelability of release sheet)
The pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was cut to prepare a 50 mm × 50 mm sample. This sample was fixed to a support on the base side using a double-sided pressure-sensitive adhesive tape (manufactured by Lintec Corporation, TL-201) so that the non-peeled surface of the release sheet was exposed. Next, a polyester pressure-sensitive adhesive tape (Nitto Denko, No. 31B) as a pressure-sensitive adhesive tape is applied to a 1.0 cm ² region in the corner portion of the non-peeled surface of the release sheet, and the pressure-sensitive adhesive tape for bending is curved. The release sheet was peeled off from the pressure-sensitive adhesive layer of the sample. This test was performed three times. As a result, the release sheet was peeled off with the peeling adhesive tape three times, and the peelability was good (◯). It was evaluated as poor sex (x). The results are shown in Table 1.

[Test Example 3] (Evaluation of oil-based ink adhesion)
The pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was cut to prepare a sample of 100 mm × 100 mm. A 5 cm long line was drawn with an oil-based pen (manufactured by Zebra Co., McKee) on the non-peeled surface of the release sheet in this sample, and the presence or absence of repelling was visually confirmed. As a result, it was evaluated that oil repellent ink adhesion was good (O) when repelling could not be confirmed, and oil repellent ink adhesion poor (x) when repelling was confirmed. The results are shown in Table 1.

[Test Example 4] (Measurement of gel fraction)
Instead of the substrate used in the examples or comparative examples, a release sheet (RLTEC, RL-5, thickness: 38 μm) obtained by releasing one side of a polyethylene terephthalate film with a silicone-based release agent was used. A sheet was produced. Specifically, the release sheet is subjected to a release treatment on the exposed adhesive layer of the structure composed of the release sheet / adhesive layer (thickness: 2 μm) obtained in the production process of Examples or Comparative Examples. The layers were laminated so that the surface side was in contact. Thereby, the adhesive sheet which consists of a structure of a peeling sheet / adhesive layer / release sheet was produced.

  The obtained pressure-sensitive adhesive sheet was cured for 7 days under the conditions of 23 ° C. and 50% RH. Thereafter, the pressure-sensitive adhesive sheet is cut into a size of 50 mm × 90 mm, and the pressure-sensitive adhesive layer obtained by peeling the release sheets on both sides is wrapped in a polyester mesh (mesh size # 380), and the mass of the pressure-sensitive adhesive alone is placed on a precision balance. And weighed. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in 200 ml of ethyl acetate at room temperature (23 ° C.) for 48 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 2 hours. The mass of only the pressure-sensitive adhesive after drying was weighed with a precision balance. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 1.

[Test Example 5] (Measurement of adhesive strength)
The pressure-sensitive adhesive sheet obtained in the example or the comparative example was cut to prepare a sample having a width of 25 mm and a length of 250 mm. The release sheet was peeled from this sample, and the sample was affixed to non-alkali glass (Corning Corp., Eagle XG) using a 2 kg rubber roller. Then, after leaving for 24 hours under the conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec, Tensilon), in accordance with JIS Z0237: 2009, a peeling speed of 300 mm / min, a peeling angle of 180 The adhesive strength (N / 25 mm) was measured under the condition of °. The results are shown in Table 1.

[Test Example 6] (Durability evaluation)
The pressure-sensitive adhesive sheet obtained in the example or the comparative example was cut to prepare a sample having a width of 50 mm and a length of 50 mm. The release sheet was peeled from this sample, and the sample was affixed to non-alkali glass (Corning Corp., Eagle XG) using a 2 kg rubber roller.

The obtained laminate was put in an environment with a durability condition of 80 ° C. · dry for 500 hours. Then, the presence or absence of floating or foaming was confirmed visually. The evaluation criteria are as follows. The results are shown in Table 1.
○: No floating or foaming was confirmed.
X: Floating and foaming were confirmed.

  As is clear from Table 1, the release sheet of the pressure-sensitive adhesive sheet in Examples where the amount of silicone on the non-release treated surface of the release sheet was 4% or less was peelable by the pressure-sensitive adhesive tape, that is, adhered to the pressure-sensitive adhesive tape for release. In addition, there was no repellency with an oil-based pen, and the oil-based ink adhesion was also excellent.

  The pressure-sensitive adhesive sheet of the present invention is suitable as a pressure-sensitive adhesive sheet used for thin mobile electronic devices and the like.

DESCRIPTION OF SYMBOLS 1A, 1B ... Adhesive sheet 2A, 2B ... Base material 3 ... Adhesive layer 31 ... 1st adhesive layer 32 ... 2nd adhesive layer 4 ... Release sheet 41 ... 1st release sheet 42 ... 2nd release Sheet 401,411,421 ... Peeling base material 402,412,422 ... Peeling agent layer 40 ... Non-peeling surface

Claims (5)

A pressure-sensitive adhesive sheet having a base material, a pressure-sensitive adhesive layer laminated on one side or both sides of the base material, and a release sheet laminated on the surface of the pressure-sensitive adhesive layer opposite to the base material,
The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester polymer and an isocyanate-based crosslinking agent,
The (meth) acrylic acid ester polymer contains a monomer having a hydroxyl group or a monomer having a carboxyl group as a monomer unit constituting the polymer,
The pressure-sensitive adhesive layer has a thickness of 1 to 16 μm,
The substrate has a thickness of 1 to 16 μm,
The thickness of the adhesive sheet excluding the release sheet is 2 to 20 μm,
The release sheet is composed of a release substrate and a release agent layer formed on one side of the release substrate,
The thickness of the release substrate is 12 to 50 μm,
The release agent layer contains a silicone compound,
The silicone content of the surface opposite to the release agent layer in the release sheet state, and are 4% or less,
The pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive force to the alkali-free glass after peeling off the release sheet is 4 N / 25 mm or more .   The pressure-sensitive adhesive sheet according to claim 1, wherein the release substrate is made of a plastic film.   The pressure-sensitive adhesive sheet according to claim 2, wherein the plastic film constituting the release substrate is a polyethylene terephthalate film. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the release agent layer has a thickness of 0.01 to 2 µm. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein a peeling force of the release sheet is 10 to 200 mN / 25 mm.

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