JP7794569B2 - Method for manufacturing pressure-sensitive adhesive sheet and pressure-sensitive adhesive sheet - Google Patents

Description

The present invention relates to a method for producing a pressure-sensitive adhesive sheet having a transparent pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet obtainable by the method. In particular, the present invention relates to a method for producing a pressure-sensitive adhesive sheet having a transparent pressure-sensitive adhesive layer that can be used to bond a transparent optical component to another optical component, and a pressure-sensitive adhesive sheet obtainable by the method.

Image display devices such as liquid crystal display devices or organic EL display devices are composed of optical component laminates, which are stacked with various transparent optical components, including polarizing films, retardation films, transparent cover materials such as cover glass, and other transparent optical components. An adhesive sheet made of a transparent pressure-sensitive adhesive layer is used to bond these optical components together. That is, an adhesive sheet is placed between the two optical components to be bonded, and the two optical components are bonded by pressing them together to form an optical component laminate. Furthermore, adhesive sheets, which have an adhesive layer on one side of a base film, are commonly used in the manufacturing process of optical products as surface protection films to protect the optical components from scratches and dirt.

The above-mentioned adhesive sheets may contain various additives such as polymerization initiators, crosslinking agents, UV absorbers, rust inhibitors, and antistatic agents depending on the required properties.

For example, in image display devices equipped with input devices such as touch panels, a transparent, conductive printed layer made of patterned ITO (indium tin oxide) or other material is formed on the surface of the optical component. Furthermore, silver or copper wiring is formed around the periphery. It is also common for a frame-shaped black concealing area to be printed around the periphery of the transparent cover component. Adhesive sheets used to bond optical components with such printed layers and wiring are required to have high fluidity in the pressure-sensitive adhesive layer and to exhibit step absorption properties that prevent air bubbles from remaining in the printed steps.

On the other hand, plastic films used as optical components contain gases such as carbon dioxide, and gas can be generated under high temperature conditions during the manufacturing process. If the adhesive layer is soft, the generation of gas cannot be suppressed, causing the adhesive layer to float and creating bubbles. Therefore, in order to suppress gas generation from plastic films, adhesive sheets are required to increase the elastic modulus of the adhesive layer, making it harder and improving adhesion reliability.

As a pressure-sensitive adhesive sheet that combines the above-mentioned level difference absorbency and adhesive reliability, a pressure-sensitive adhesive sheet containing a hybrid pressure-sensitive adhesive (sometimes referred to herein as a "hybrid pressure-sensitive adhesive sheet") is widely used (see, for example, Patent Document 1). A hybrid pressure-sensitive adhesive is a pressure-sensitive adhesive composition that cures in stages by blending two types of polymerization initiators and cross-linking agents (sometimes referred to herein as "triggers") that differ in curing initiation conditions, such as heat or light. In a hybrid pressure-sensitive adhesive sheet, one trigger (sometimes referred to herein as a "first trigger") first creates a semi-cured state with high fluidity and excellent level difference absorbency, allowing it to fully conform to the level difference. Then, the other trigger (sometimes referred to herein as a "second trigger") completes the curing, thereby improving adhesive reliability.

In addition, image display devices are sometimes required to have UV protection to prevent deterioration of components within the image display device due to incident UV rays. Organic EL display devices, in particular, use organic compounds as light-emitting elements, which cause faster deterioration due to UV rays than liquid crystal display devices. Furthermore, as optical components such as polarizing films and protective films become thinner, their resistance to UV rays has decreased, making it essential to provide a UV-absorbing layer. For example, it is known to use a pressure-sensitive adhesive sheet equipped with a UV-absorbing layer containing a UV absorber (see, for example, Patent Document 2).

Furthermore, as sensors become larger and frames become narrower in image display devices and input devices, more and more devices are being equipped with copper wiring. Copper has excellent electrical conductivity and is a useful material for wiring, but it is susceptible to oxidation and corrosion. It is known to incorporate a rust inhibitor into the adhesive sheet to inhibit the oxidation and corrosion of copper wiring (see, for example, Patent Document 3).

Furthermore, there is concern that static electricity generated when peeling a surface protection film from an optical component such as a polarizing film could damage the electrical circuits of the image display device. Static electricity can also attract dust and reduce workability. For example, it is known to incorporate an antistatic agent into the pressure-sensitive adhesive layer to prevent static electricity from being generated by the surface protection film (see, for example, Patent Document 4).

International Publication No. WO2016/170875 Japanese Patent Application Laid-Open No. 2012-211305 International Publication No. WO2015/145767 JP 2016-128537 A

When the various additives mentioned above are blended into a pressure-sensitive adhesive sheet, they may affect various physical properties of the pressure-sensitive adhesive sheet, such as adhesive strength and modulus of elasticity. In particular, in recent years, as image display devices have become lighter and thinner, pressure-sensitive adhesive layers have also become thinner, and there is an increasing demand for higher concentrations of additives in pressure-sensitive adhesive sheets to satisfy required properties. There is also an increasing demand for blending two or more additives to impart multiple functions to pressure-sensitive adhesive sheets, but the additives may interfere with each other, resulting in a trade-off. As such, the problems associated with blending various additives into pressure-sensitive adhesive sheets are becoming more apparent.

Given this background, when incorporating additives into adhesive sheets, it has become necessary to start from scratch and design the amounts of various additives to be added, the adhesive composition (such as the monomer composition of the base polymer), the thickness of the adhesive sheet, and curing conditions, in order to not only satisfy the required properties of the additives but also to minimize changes in the adhesive strength, elastic modulus, and other physical properties of the adhesive sheet, as well as interference between additives. Furthermore, there is the problem that achieving both the required properties of the additives and the physical properties of the adhesive sheet limits the degree of freedom in designing additive selection, curing conditions, and other aspects.

For example, in hybrid adhesive compositions, two types of triggers with different curing conditions are used in combination, which requires a combination of triggers and strict curing conditions to be set so that the first trigger does not promote the curing reaction caused by the second trigger, resulting in the problem of extremely limited design freedom in terms of trigger selection and curing conditions.

For example, when the first trigger is a thermal polymerization initiator and the second trigger is a photopolymerization initiator, the curing of the second trigger may proceed during the thermal curing of the first trigger, making it necessary to strictly control the curing reaction. Also, there is a problem that a thick adhesive layer takes a long time to thermally cure, resulting in a decrease in production efficiency.
Furthermore, when the first trigger is a photopolymerization initiator and the second trigger is a thermal polymerization initiator, process control is required to prevent exposure to high temperatures in the process after photocuring, and it is also difficult to heat the adhesive sheet after bonding, making this method less practical.
Furthermore, when the first trigger and the second trigger are photopolymerization initiators, the light absorption wavelength bands of the two types of photopolymerization initiators need to be sufficiently separated from each other. Furthermore, when the above-mentioned ultraviolet absorber is further blended, it is also necessary to distinguish from the wavelength range thereof, which extremely narrows the design possibilities.
When the first trigger and the second trigger are thermal polymerization initiators, the second trigger inevitably progresses when the first trigger is thermally cured, making it difficult to achieve a two-stage curing reaction.

Furthermore, adding a sufficient amount of UV absorber to the adhesive composition to provide UV protection can have an adverse effect on the physical properties and curing properties of the adhesive. In particular, when a photocurable adhesive sheet containing a UV absorber is cured by UV irradiation, the UV absorber absorbs the UV light, resulting in poor curing properties and reduced productivity.

Furthermore, photocurable adhesive sheets containing UV absorbers have the problem of differences in physical properties such as adhesiveness and viscoelasticity between the front and back of the adhesive sheet. This is because UV light is absorbed by the UV absorber as it passes through the adhesive layer, and the UV irradiance decreases the deeper it is from the UV-irradiated surface, resulting in differences in curing speed between the front and back.

In addition, in the above patent documents, additives are blended into the adhesive composition and dissolved uniformly, but anti-rust agents and anti-static agents, etc., are intended to function only near the interface with the optical component to be bonded. However, in order to impart sufficient anti-rust and anti-static properties to the surface of the adhesive sheet, it is necessary to blend the additives throughout the adhesive layer, which poses a dilemma as it affects the physical properties of the adhesive sheet.

The present invention was conceived in light of the above circumstances, and aims to provide a method for manufacturing an adhesive sheet that minimizes changes in the physical properties of the adhesive sheet and interference between additives, even when additives are blended into the adhesive sheet, while allowing for greater freedom in design, such as additive selection and curing conditions, and facilitating easy design.

Another object of the present invention is to provide an adhesive sheet that is easy to design, allowing for greater freedom in designing additive selection and curing conditions, while minimizing changes in the physical properties of the adhesive sheet and interference between additives, even when additives are blended into the adhesive sheet.

As a result of extensive research to achieve the above-mentioned objective, the inventors have discovered that by applying and penetrating a solution of additives after curing the adhesive layer of an adhesive sheet, it is possible to minimize the impact on the physical properties of the adhesive layer and interference between additives, thereby obtaining an adhesive sheet that has excellent physical properties for the adhesive layer and exhibits the excellent required properties of the additives. They have also discovered that this significantly increases the degree of freedom in designing the additive selection and curing conditions. The present invention was completed based on these findings.

That is, the first aspect of the present invention is
forming a pressure-sensitive adhesive layer made of a transparent pressure-sensitive adhesive base material on a support;
Curing the pressure-sensitive adhesive layer,
Prepare a solution of additives,
applying the solution to one surface of the cured pressure-sensitive adhesive layer, and allowing the additive contained in the solution to penetrate the pressure-sensitive adhesive layer from the one surface in a thickness direction;
The method for producing a pressure-sensitive adhesive sheet includes a step of drying the pressure-sensitive adhesive layer.

By curing the adhesive layer before incorporating the additive into the adhesive layer, the effect of the additive on the adhesive layer can be reduced. Therefore, changes in the physical properties of the adhesive layer due to the additive can be minimized.

By applying a solution of additives to the cured adhesive layer, the additives penetrate into the adhesive layer. This allows the adhesive layer to be given the required properties through the additives. Furthermore, the transparency of the adhesive layer is maintained as the additives penetrate in solution.

The adhesive layer is then dried by heating or other means. This process returns the adhesive layer to a state close to that before it was applied. In other words, because the adhesive layer has been hardened, its physical properties, such as adhesive strength and elastic modulus, are restored to a state close to that before the solution was applied.

Because the adhesive layer is cured before the additives are added, once the adhesive composition's composition, curing conditions, and physical properties are determined, there is no need to redesign the composition by adding additives, and the thickness of the adhesive layer can be easily changed. Then, by changing the coating conditions for the additive solution, the required properties imparted to the adhesive layer can be controlled. In this way, controlling the physical properties of the adhesive layer and controlling the required properties by the additives can be separated, eliminating the need to redesign the adhesive layer from scratch when changing the thickness of the adhesive layer or the amount of additive added, resulting in greater efficiency.

In the method for manufacturing a pressure-sensitive adhesive sheet according to the first aspect of the present invention, the additive solution may be a solution in which the additive is dissolved in a solvent, and the method may include a step of evaporating the solvent of the solution by drying the pressure-sensitive adhesive layer.
By applying a solution of an additive dissolved in a solvent to the cured pressure-sensitive adhesive layer, the solvent penetrates into the pressure-sensitive adhesive layer, causing the pressure-sensitive adhesive layer to swell, and the additive dissolved in the solvent penetrates into the pressure-sensitive adhesive layer swollen by the solvent, thereby imparting the required properties of the additive to the pressure-sensitive adhesive layer, and also maintaining the transparency of the pressure-sensitive adhesive layer due to the penetration of the additive in solution.
The solvent that has permeated the adhesive layer evaporates when heated, etc., and the adhesive layer returns to a state close to that before swelling. In other words, since the adhesive layer has been cured once, the physical properties such as adhesive strength and elastic modulus are restored to a state close to that before the solution was applied.

Furthermore, for example, by individually applying and drying solutions of two or more additives to the adhesive layer, it is possible to reduce interference between the additives and efficiently impart a variety of required properties.

The method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention may further include the step of attaching a release sheet to the surface of the pressure-sensitive adhesive layer opposite the support. Attaching a release sheet is preferable in that it protects the surface of the pressure-sensitive adhesive layer.

In the method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention, the additive may be at least one selected from the group consisting of a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an antistatic agent. These additives are preferred examples for achieving the desired effects of the present invention.

When the additive is at least one selected from a polymerization initiator and a crosslinking agent, the first aspect of the present invention is useful as a method for producing a hybrid pressure-sensitive adhesive sheet.

When the first aspect of the present invention is a method for producing a hybrid pressure-sensitive adhesive sheet,
the PSA base material contains a first polymerization initiator and a first crosslinking agent as a first trigger;
the curing is caused by a reaction between the first polymerization initiator and the first crosslinking agent,
The additive is preferably at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent, serving as a second trigger.
The first polymerization initiator may be the same as the second polymerization initiator.

Because the curing reaction caused by the first trigger is completed before the second trigger is added, there is no need to combine it with the first trigger or set strict curing conditions that would prevent the curing reaction caused by the second trigger from progressing, significantly increasing the design freedom of hybrid pressure-sensitive adhesive sheets.

In other words, because the curing reactions of the first and second triggers are separated, there is an extremely high degree of freedom in selecting the combination of the first and second triggers. For example, it is possible to freely select a combination in which both the first and second triggers are photopolymerization initiators, a combination in which the first trigger is a thermal polymerization initiator and the second trigger is a photopolymerization initiator, or a combination in which the first trigger is a photopolymerization initiator and the second trigger is a thermal polymerization initiator. It is also possible to combine both the first and second triggers as thermal polymerization initiators, which was difficult with conventional hybrid pressure-sensitive adhesive sheets. Furthermore, when both the first and second triggers are photopolymerization initiators, it is also possible for the light absorption wavelength bands of the two types of photopolymerization initiators to overlap or be similar.

Furthermore, it is also possible to combine the same polymerization initiator (whether a thermal polymerization initiator or a photopolymerization initiator) as the first trigger and the second trigger, which was not possible with conventional hybrid pressure-sensitive adhesive sheets.
In this way, the degree of freedom in the combination of the first trigger and the second trigger is extremely high, and it is also possible to combine the same triggers, which is advantageous in that it makes it possible to avoid the use of a polymerization initiator that may cause coloration or deterioration of the pressure-sensitive adhesive layer.

Furthermore, because the curing reactions of the first and second triggers are separate and do not interfere with each other, there is no need to set strict conditions to control each curing reaction. For example, with the first trigger, there is no need to set conditions that prevent the second trigger from progressing. Once the curing conditions that impart excellent step absorbency to the adhesive layer are determined, the adhesive reliability that should be imparted to the adhesive layer can be easily controlled by subsequently changing the application conditions and curing conditions for the second trigger solution.

In the first aspect of the present invention, when the additive is an ultraviolet absorber, the pressure-sensitive adhesive layer can be cured without being affected by the ultraviolet absorber by irradiating the pressure-sensitive adhesive layer with ultraviolet light before adding the ultraviolet absorber. This minimizes productivity reductions due to deterioration of curing properties caused by the ultraviolet absorber, and changes in the physical properties of the pressure-sensitive adhesive layer, such as differences in physical properties between the front and back surfaces.

In addition, because the adhesive layer is cured before the UV absorber is added, once the composition, curing conditions, physical properties, etc. of the adhesive composition have been decided, there is no need to redesign the composition by adding a UV absorber, and the thickness of the adhesive layer can be easily changed. Then, by changing the coating conditions for the UV absorber solution, the UV absorption function imparted to the adhesive layer can be controlled. In this way, since control of the physical properties of the adhesive layer and control of the UV absorption function can be separated, there is no need to design the adhesive layer from scratch to change the thickness or UV absorption function of the adhesive layer, which is efficient.

Furthermore, for example, when blending an ultraviolet absorber into a hybrid pressure-sensitive adhesive sheet, the ultraviolet absorber can be added after curing with the first and second triggers, so there is no need to distinguish between the absorption wavelength bands of the photopolymerization initiator and the ultraviolet absorber used as the first and second triggers. This significantly increases the freedom of choice when selecting a combination of photopolymerization initiator and ultraviolet absorber.

In the first aspect of the present invention, when the additive is at least one selected from a polymerization initiator and a crosslinking agent, it is also preferable that the additive further comprises an ultraviolet absorber. By including an ultraviolet absorber in addition to at least one selected from a polymerization initiator and a crosslinking agent, a hybrid pressure-sensitive adhesive sheet containing the ultraviolet absorber can be produced in a single coating step, thereby improving production efficiency. Furthermore, when a hybrid pressure-sensitive adhesive sheet containing the ultraviolet absorber is irradiated with ultraviolet light, the ultraviolet absorber absorbs the ultraviolet light and generates heat, thereby accelerating the curing reaction and improving adhesion reliability, which is even more preferable.

In the first aspect of the present invention, when the additive is a rust inhibitor or antistatic agent, sufficient rust prevention or antistatic function can be imparted to the surface of the adhesive layer by applying and penetrating a solution of the rust inhibitor or antistatic agent onto the surface of the cured adhesive layer. Because it is not necessary to uniformly disperse the rust inhibitor or antistatic agent in the adhesive layer, changes in physical properties such as the elastic modulus of the adhesive layer caused by the rust inhibitor or antistatic agent can be minimized, and the amount of rust inhibitor or antistatic agent used can also be reduced.

Furthermore, because the adhesive layer is cured before the rust inhibitor or antistatic agent is added, once the adhesive composition's composition, curing conditions, physical properties, etc. are determined, there is no need to redesign the composition by adding a rust inhibitor or antistatic agent, and the thickness of the adhesive layer can be easily changed. Then, by changing the application conditions for the rust inhibitor or antistatic agent solution, the rust prevention or antistatic properties imparted to the adhesive layer can be controlled. In this way, since control of the adhesive layer's physical properties and control of the rust prevention or antistatic properties provided by the rust inhibitor or antistatic agent can be separated, there is no need to redesign the adhesive layer from scratch when changing the thickness of the adhesive layer or the amount of rust inhibitor or antistatic agent added, which is efficient.

Moreover, a second aspect of the present invention is
A method for producing an optical member laminate including a substrate made of an optical member and a pressure-sensitive adhesive layer,
bonding a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet obtained by the method for producing a hybrid pressure-sensitive adhesive sheet according to the first aspect of the present invention to a main surface of a substrate made of the optical member;
a step of curing the pressure-sensitive adhesive layer by a reaction with at least one agent selected from the group consisting of the second polymerization initiator and the second crosslinking agent,
A method for producing an optical component laminate is provided.

In the method for producing an optical member laminate according to the second aspect of the present invention,
a main surface of the substrate made of the optical member has a printing layer;
The pressure-sensitive adhesive layer is preferably bonded so as to fill in any step between the main surface of the substrate made of the optical member and the printed layer.

A second aspect of the present invention is a method for producing an optical component laminate using a pressure-sensitive adhesive sheet (hybrid pressure-sensitive adhesive sheet) obtained by the method for producing a hybrid pressure-sensitive adhesive sheet according to the first aspect of the present invention.
The pressure-sensitive adhesive layer of the hybrid pressure-sensitive adhesive sheet used in the second aspect of the present invention is cured with a first polymerization initiator and a first crosslinking agent (first trigger), but is in a semi-cured, highly fluid state before being cured with at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent (second trigger). Therefore, even if the main surface of the substrate made of the optical component has a printed layer, the pressure-sensitive adhesive layer can sufficiently conform to and bond to the step between the main surface of the substrate made of the optical component and the printed layer so as to fill this step.

Next, the pressure-sensitive adhesive layer is cured by a reaction with at least one agent (second trigger) selected from the group consisting of the second polymerization initiator and the second crosslinking agent, thereby increasing the elastic modulus of the pressure-sensitive adhesive layer and improving adhesion reliability.

Moreover, a third aspect of the present invention is
A pressure-sensitive adhesive sheet having a support and a transparent pressure-sensitive adhesive layer on the support,
the pressure-sensitive adhesive layer is a single layer made of a transparent pressure-sensitive adhesive base material and having two opposing main surfaces;
an additive dissolved in the pressure-sensitive adhesive layer;
The adhesive sheet is characterized in that, when the single-layer adhesive layer is divided into two equal parts in the thickness direction, the concentration of the additive in a region to which a first main surface, one of the two main surfaces, belongs is different from the concentration of the additive in a region to which a second main surface, the other main surface, belongs.

The pressure-sensitive adhesive sheet of the third aspect of the present invention can be obtained by the pressure-sensitive adhesive sheet manufacturing method of the first aspect of the present invention. By applying a solution of an additive to one side of the pressure-sensitive adhesive layer and allowing it to penetrate, a difference in the concentration of the additive can be created between the front and back of the pressure-sensitive adhesive layer. As described above, a pressure-sensitive adhesive sheet that can be configured in this way can minimize changes in physical properties caused by the additive.

In the method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention, depending on conditions such as the thickness of the pressure-sensitive adhesive layer and the penetration time of the additive, the concentration of the additive may be the same or substantially the same on both sides of the pressure-sensitive adhesive layer. Therefore, the present invention also includes cases where a pressure-sensitive adhesive sheet in which the concentration of the additive is the same or substantially the same on both sides of the pressure-sensitive adhesive layer is obtained by the method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention.

In the adhesive sheet of the third aspect of the present invention, the adhesive layer is preferably a cured adhesive layer. This configuration is preferable in that it minimizes changes in physical properties due to additives.

In the pressure-sensitive adhesive sheet of the third aspect of the present invention, it is preferable that the second main surface faces the support, and the concentration of the additive in the region to which the first main surface belongs is higher than the concentration of the additive in the region to which the second main surface belongs. This configuration can be obtained by applying a solution of the additive to the first main surface.

In the pressure-sensitive adhesive sheet of the third aspect of the present invention, it is preferable that the single pressure-sensitive adhesive layer has a concentration gradient of the additive in the thickness direction. This configuration can be obtained by applying a solution of the additive to one main surface of the pressure-sensitive adhesive layer and allowing it to penetrate.

In the pressure-sensitive adhesive sheet of the third aspect of the present invention, the support preferably comprises a release sheet. In this case, the support made of a release sheet is preferably disposed on both sides of the pressure-sensitive adhesive layer. Having the support be a release sheet is preferable in that it can be bonded to a transparent optical component after being peeled off.

In the pressure-sensitive adhesive sheet of the third aspect of the present invention, the additive is preferably at least one selected from the group consisting of a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an antistatic agent. These additives are suitable examples for achieving the desired effects of the present invention.

When the additive is at least one selected from the group consisting of a polymerization initiator and a crosslinking agent, the third aspect of the present invention is useful as a hybrid pressure-sensitive adhesive sheet.

In the third aspect of the present invention, when the additive is at least one selected from a polymerization initiator and a crosslinking agent, it is also preferable that the additive further comprises an ultraviolet absorber. When the additive comprises an ultraviolet absorber in addition to at least one selected from a polymerization initiator and a crosslinking agent, the pressure-sensitive adhesive sheet of the third aspect of the present invention can be a hybrid pressure-sensitive adhesive sheet containing an ultraviolet absorber. When a hybrid pressure-sensitive adhesive sheet containing an ultraviolet absorber is irradiated with ultraviolet light, the ultraviolet absorber absorbs the ultraviolet light and generates heat, thereby accelerating the curing reaction and improving adhesion reliability, which is preferable.

When the third aspect of the present invention is a hybrid pressure-sensitive adhesive sheet,
the PSA base material contains a first polymerization initiator and a first crosslinking agent as a first trigger;
the curing is caused by a reaction between the first polymerization initiator and the first crosslinking agent,
The additive is preferably at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent, serving as a second trigger.
The first polymerization initiator may be the same as the second polymerization initiator.

When the third aspect of the present invention is a hybrid pressure-sensitive adhesive sheet, the same effects as when the first aspect of the present invention is a method for producing a hybrid pressure-sensitive adhesive sheet can be achieved.
Furthermore, by making the concentration of the second trigger in the region to which the first main surface belongs different from the concentration of the second trigger in the region to which the second main surface belongs, it is possible to control the crosslinking density between the first main surface and the second main surface, and to create differences in physical properties such as elastic modulus between the front and back of the pressure-sensitive adhesive layer. This configuration is suitable, for example, for bendable flexible displays. When a flexible display is bent, tensile stress is generally applied to the outside and compressive stress is applied to the inside, with the outside stress being stronger than the inside stress. Therefore, by placing the side of the pressure-sensitive adhesive layer with a higher concentration of the second trigger on the outside when bending the flexible display, it is possible to improve durability against bending.

When the additive in the pressure-sensitive adhesive sheet of the third aspect of the present invention is an ultraviolet absorber, the same effects can be achieved as when the additive in the pressure-sensitive adhesive sheet manufacturing method of the first aspect of the present invention is an ultraviolet absorber. In other words, the pressure-sensitive adhesive sheet of the third aspect of the present invention, in which the additive is an ultraviolet absorber, can minimize reduced productivity due to deterioration of curing properties caused by the ultraviolet absorber, and changes in physical properties such as differences between the front and back surfaces.

When the additive in the pressure-sensitive adhesive sheet of the third aspect of the present invention is a rust inhibitor or antistatic agent, the same effects can be achieved as when the additive in the pressure-sensitive adhesive sheet manufacturing method of the first aspect of the present invention is a rust inhibitor or antistatic agent. That is, the pressure-sensitive adhesive sheet of the third aspect of the present invention, in which the additive is a rust inhibitor or antistatic agent, can impart excellent rust prevention or antistatic function to one of its main surfaces (the first or second main surface) by distributing the rust inhibitor or antistatic agent at a higher concentration on that main surface. Because it is not necessary to uniformly disperse the rust inhibitor or antistatic agent in the pressure-sensitive adhesive layer, changes in the physical properties of the pressure-sensitive adhesive layer due to the rust inhibitor or antistatic agent can be minimized, and the amount of rust inhibitor or antistatic agent used can also be reduced.

In the pressure-sensitive adhesive sheet of the third aspect of the present invention, the thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 500 μm. A thickness within this range is suitable for forming a concentration gradient of the additive in the thickness direction of the pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer is more preferably 5 μm to 400 μm, and even more preferably 5 μm to 350 μm.

Moreover, a fourth aspect of the present invention is
a substrate made of an optical member;
An optical member laminate comprising:
the pressure-sensitive adhesive layer is laminated on a main surface of the substrate made of the optical member,
The present invention provides an optical member laminate, wherein the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive layer of the hybrid pressure-sensitive adhesive sheet according to the third aspect of the present invention.

In a fourth aspect of the present invention,
a main surface of the substrate made of the optical member has a print layer;
The pressure-sensitive adhesive layer is preferably laminated so as to fill in any step between the main surface of the substrate made of the optical member and the printed layer.

In addition, in a fourth aspect of the present invention,
The cured product is preferably a product obtained by the reaction of at least one selected from the group consisting of the second polymerization initiator and the second crosslinking agent.

A fourth aspect of the present invention is an optical member laminate using the hybrid pressure-sensitive adhesive sheet according to the third aspect of the present invention.
The optical member laminate according to the fourth aspect of the present invention can be produced by the method according to the second aspect of the present invention, and can achieve the same effects.

According to the method for producing a pressure-sensitive adhesive sheet and the pressure-sensitive adhesive sheet of the present invention, even when additives are blended into the pressure-sensitive adhesive sheet, changes in the physical properties of the pressure-sensitive adhesive layer and interference between the additives are unlikely to occur.
Furthermore, there is no need to design the adhesive layer from scratch when changing the thickness of the adhesive layer or the amount of additives added, which is efficient.

FIG. 1 is a schematic diagram showing steps for carrying out one embodiment of the method for producing a pressure-sensitive adhesive sheet of the present invention, in which (a) is a pressure-sensitive adhesive layer forming step, (b) is a pressure-sensitive adhesive layer curing step, (c) is a solution applying step, (d) is a solution penetrating step, and (e) is a drying step. FIG. 2(a) is a cross-sectional view showing one embodiment of a pressure-sensitive adhesive sheet according to the present invention, and FIG. 2(b) is a cross-sectional view showing another embodiment of a pressure-sensitive adhesive sheet according to the present invention. FIG. 3 is a cross-sectional view of an optical member laminate showing an example of the simplest embodiment using the pressure-sensitive adhesive sheet according to the present invention. FIG. 4 is a schematic diagram showing steps for carrying out one embodiment of the method for producing an optical member laminate using the hybrid adhesive sheet of the present invention. Figure 5 is a graph showing the results of TOF-SIMS analysis of the pressure-sensitive adhesive sheets of Example 9 and Comparative Example 9. Figure 5(a) shows the results of Example 9, and Figure 5(b) shows the results of Comparative Example 9. In Figure 5, the scale on the left vertical axis shows the intensity of butyl acrylate (BA) and N-vinylpyrrolidone (NVP), and the scale on the right vertical axis shows the intensity of the ultraviolet absorber (Tinosorb S).

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these and is merely an example.
1(a) to 1(e) are diagrams schematically illustrating steps for carrying out one embodiment of the method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention.
First, as shown in FIG. 1(a), an adhesive layer 10 made of a transparent adhesive base material is formed on a support S1 (adhesive layer forming step).

The support is not particularly limited, but a plastic film is preferred. Examples of materials for the plastic film include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymers, and cyclic olefin polymers such as "ARTON" (a cyclic olefin polymer manufactured by JSR Corporation) and "ZEONOR" (a cyclic olefin polymer manufactured by Zeon Corporation). These plastic materials may be used alone or in combination of two or more.
The support may be a release sheet. The release sheet is not particularly limited, but examples thereof include plastic films whose surfaces are treated with a release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based release agent.

The adhesive base material is not particularly limited as long as it is a transparent material with adhesive properties suitable for optical applications. For example, it can be appropriately selected from acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. From the perspectives of transparency, processability, and durability, acrylic adhesives are preferred. The adhesive base material can use any of the above adhesives alone or in combination of two or more. The acrylic polymer used as the base polymer for the acrylic adhesive is not particularly limited, but is preferably a homopolymer or copolymer of a monomer primarily composed of a (meth)acrylic acid alkyl ester. Here, the term "(meth)acrylic" is used to mean either or both of "acrylic" and "methacrylic," and similarly applies to other cases. In this invention, the term "acrylic polymer" is used to include not only the above-mentioned (meth)acrylic acid alkyl ester but also other monomers copolymerizable therewith.

When the PSA base material contains an acrylic polymer that serves as an acrylic PSA, the acrylic polymer preferably contains, as the predominant monomer unit by weight, a monomer unit derived from an alkyl acrylate ester having a linear or branched alkyl group and/or an alkyl methacrylate ester having a linear or branched alkyl group.

Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group that form the monomer units of the acrylic polymer, i.e., (meth)acrylic acid alkyl esters having a linear or branched alkyl group that are contained in the monomer components that form the acrylic polymer, include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and Examples of the alkyl (meth)acrylate include alkyl (meth)esters having a linear or branched alkyl group having 1 to 20 carbon atoms, such as octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. As the alkyl (meth)acrylate for the acrylic polymer, one type of alkyl (meth)acrylate may be used, or two or more types of alkyl (meth)acrylates may be used. In this embodiment, the (meth)acrylic acid alkyl ester used for the acrylic polymer is preferably at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and isostearyl acrylate.

The proportion of monomer units derived from (meth)acrylic acid alkyl esters having a linear or branched alkyl group in the acrylic polymer is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight or more. In other words, the proportion of (meth)acrylic acid alkyl esters in the monomer component composition of the raw materials used to form the acrylic polymer is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight or more.

The acrylic polymer contained in the PSA base material may contain a monomer unit derived from an alicyclic monomer. Examples of alicyclic monomers that form the monomer units of the acrylic polymer, i.e., alicyclic monomers contained in the monomer components for forming the acrylic polymer, include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic hydrocarbon ring, and (meth)acrylic acid esters having a tricyclic or higher hydrocarbon ring. Examples of (meth)acrylic acid cycloalkyl esters include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of (meth)acrylic acid esters having a bicyclic hydrocarbon ring include bornyl (meth)acrylate and isobornyl (meth)acrylate. Examples of (meth)acrylic acid esters having three or more hydrocarbon rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate. As the alicyclic monomer for the acrylic polymer, one type of alicyclic monomer may be used, or two or more types of alicyclic monomers may be used. In this embodiment, the alicyclic monomer for the acrylic polymer is preferably at least one selected from the group consisting of cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, and isobornyl methacrylate.

The proportion of monomer units derived from alicyclic monomers in the acrylic polymer is preferably 5 to 60% by weight, more preferably 10 to 50% by weight, and even more preferably 12 to 40% by weight, from the viewpoint of achieving appropriate flexibility in the PSA base material formed containing the acrylic polymer.

The acrylic polymer contained in the PSA base material may contain a monomer unit derived from a hydroxyl group-containing monomer. A hydroxyl group-containing monomer is a monomer that has at least one hydroxyl group within the monomer unit. When the acrylic polymer in the PSA base material contains a hydroxyl group-containing monomer unit, the PSA base material is more likely to achieve adhesiveness and appropriate cohesive strength. In addition, the hydroxyl group can also serve as a reaction site with the crosslinking agent described below.

Hydroxyl group-containing monomers for forming the monomer units of the acrylic polymer, i.e., hydroxyl group-containing monomers contained in the monomer components for forming the acrylic polymer, include, for example, hydroxyl group-containing (meth)acrylic acid esters, vinyl alcohol, and allyl alcohol. Examples of hydroxyl group-containing (meth)acrylic acid esters include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxyl group-containing monomer for the acrylic polymer, one type of hydroxyl group-containing monomer may be used, or two or more types of hydroxyl group-containing monomers may be used. In this embodiment, the hydroxyl group-containing monomer for the acrylic polymer is preferably at least one selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and 4-hydroxybutyl methacrylate.

The proportion of monomer units derived from hydroxyl group-containing monomers in the acrylic polymer is preferably 1% by weight or more, more preferably 2% by weight or more, more preferably 3% by weight or more, more preferably 7% by weight or more, more preferably 10% by weight or more, and more preferably 15% by weight or more. The proportion of monomer units derived from hydroxyl group-containing monomers in the acrylic polymer is preferably 35% by weight or less, more preferably 30% by weight or less. These configurations regarding the proportion of hydroxyl group-containing monomers are suitable for achieving adhesive properties and appropriate cohesive strength in a pressure-sensitive adhesive base material formed containing the acrylic polymer.

The acrylic polymer contained in the PSA base material may contain a monomer unit derived from a nitrogen-atom-containing monomer. A nitrogen-atom-containing monomer is a monomer that has at least one nitrogen atom within the monomer unit. When the acrylic polymer in the PSA base material contains a nitrogen-atom-containing monomer unit, the PSA base material is more likely to achieve hardness and good adhesive reliability.

Nitrogen-atom-containing monomers that form the monomer units of the acrylic polymer, i.e., nitrogen-atom-containing monomers contained in the monomer components that form the acrylic polymer, include, for example, N-vinyl cyclic amides and (meth)acrylamides. Examples of N-vinyl cyclic amides that are nitrogen-atom-containing monomers include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione. Examples of (meth)acrylamides as nitrogen atom-containing monomers include (meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-n-butyl(meth)acrylamide, N-octyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, and N,N-diisopropyl(meth)acrylamide. As the nitrogen atom-containing monomer for the acrylic polymer, one type of nitrogen atom-containing monomer may be used, or two or more types of nitrogen atom-containing monomers may be used. In this embodiment, N-vinyl-2-pyrrolidone is preferably used as the nitrogen atom-containing monomer for the acrylic polymer.

The proportion of monomer units derived from nitrogen-atom-containing monomers in the acrylic polymer is preferably 1% by weight or more, more preferably 3% by weight or more, and more preferably 5% by weight or more, from the viewpoint of achieving appropriate hardness, adhesion, and transparency in a pressure-sensitive adhesive base material formed containing the acrylic polymer. Furthermore, the proportion of monomer units derived from nitrogen-atom-containing monomers in the acrylic polymer is preferably 30% by weight or less, more preferably 25% by weight or less, from the viewpoint of achieving sufficient transparency in a pressure-sensitive adhesive base material formed containing the acrylic polymer and preventing the material from becoming too hard and achieving good adhesive reliability.

The acrylic polymer contained in the PSA base material may contain a monomer unit derived from a carboxy group-containing monomer. A carboxy group-containing monomer is a monomer that has at least one carboxy group within the monomer unit. When the acrylic polymer in the PSA base material contains a carboxy group-containing monomer unit, the PSA base material may achieve good adhesive reliability. In addition, the carboxy group can also serve as a reaction site with the crosslinking agent described below.

Carboxy group-containing monomers for forming the monomer units of the acrylic polymer, i.e., carboxy group-containing monomers included in the monomer components for forming the acrylic polymer, include, for example, (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. As the carboxy group-containing monomer for the acrylic polymer, one type of carboxy group-containing monomer may be used, or two or more types of carboxy group-containing monomers may be used. In this embodiment, acrylic acid is preferably used as the carboxy group-containing monomer for the acrylic polymer.

The proportion of monomer units derived from carboxyl group-containing monomers in the acrylic polymer is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, from the viewpoint of ensuring good adhesive reliability in a pressure-sensitive adhesive base material formed containing the acrylic polymer by utilizing the contribution of interactions between polar groups and carboxyl groups when polar groups are present on the surface of an adherend. Furthermore, the proportion of monomer units derived from carboxyl group-containing monomers in the acrylic polymer is preferably 20% by weight or less, more preferably 15% by weight or less, from the viewpoint of preventing the pressure-sensitive adhesive base material formed containing the acrylic polymer from becoming too hard and achieving good adhesive reliability.

The acrylic polymer contained in the adhesive base material may have a crosslinked structure derived from a crosslinking agent. The crosslinked structure of the adhesive base material increases the viscosity and improves shape stability, making it easier to form an adhesive layer on the support S1. Examples of crosslinking agents include copolymerizable crosslinking agents such as polyfunctional (meth)acrylates and thermosetting crosslinking agents. The acrylic polymer may have a crosslinked structure derived solely from a polyfunctional (meth)acrylate, a crosslinked structure derived solely from a thermosetting crosslinking agent, or a crosslinked structure derived from both a polyfunctional (meth)acrylate and a thermosetting crosslinking agent.
This crosslinking agent is a crosslinking agent (first crosslinking agent) that constitutes the first trigger when the pressure-sensitive adhesive sheet of the present invention is a hybrid pressure-sensitive adhesive sheet.

Examples of polyfunctional (meth)acrylates include 1,6-hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, and vinyl (meth)acrylate. As polyfunctional (meth)acrylates for acrylic polymers, one type of polyfunctional (meth)acrylate may be used, or two or more types of polyfunctional (meth)acrylates may be used. In this embodiment, the polyfunctional (meth)acrylate used for the acrylic polymer is preferably at least one selected from the group consisting of 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, and trimethylolpropane triacrylate.

The proportion of the monomer unit derived from the polyfunctional (meth)acrylate in the acrylic polymer is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, more preferably 0.05% by weight or more, and more preferably 0.1% by weight or more. The proportion of the monomer unit derived from the polyfunctional (meth)acrylate in the acrylic polymer is preferably 1% by weight or less, more preferably 0.5% by weight or less. These configurations regarding the proportion of the polyfunctional (meth)acrylate are suitable for achieving appropriate hardness, adhesiveness, and shape stability in a pressure-sensitive adhesive base material formed containing the acrylic polymer.

Examples of thermosetting crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. The adhesive base material may contain one type of thermosetting crosslinking agent, or two or more types of thermosetting crosslinking agents. Preferably, at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents is used.

Examples of isocyanate-based crosslinking agents include lower aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. Examples of lower aliphatic polyisocyanates include 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate. Examples of alicyclic polyisocyanates include cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate. Examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Other examples of isocyanate crosslinking agents include commercially available products such as trimethylolpropane/tolylene diisocyanate adduct (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane/hexamethylene diisocyanate adduct (trade name "Coronate HL", manufactured by Nippon Polyurethane Industry Co., Ltd.), and trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N", manufactured by Mitsui Chemicals, Inc.).

Examples of epoxy crosslinkers (polyfunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. Epoxy-based crosslinking agents also include epoxy-based resins having two or more epoxy groups. Additionally, epoxy-based crosslinking agents include commercially available products such as "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

When the adhesive base material contains the above-described thermosetting crosslinking agent for crosslinking between acrylic polymers, the content of the thermosetting crosslinking agent in the adhesive base material is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, per 100 parts by weight of the acrylic polymer in the adhesive base material, from the viewpoints of improving the shape stability of the adhesive base material, facilitating the formation of an adhesive layer on the support S1, and achieving sufficient adhesive reliability to the adherend. Furthermore, the content of the thermosetting crosslinking agent in the adhesive base material is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, per 100 parts by weight of the acrylic polymer in the adhesive base material, from the viewpoints of imparting appropriate flexibility to the adhesive base material and achieving good adhesive strength.

When the adhesive base material contains the above-mentioned acrylic polymer as an adhesive, the content of the acrylic polymer in the adhesive base material is, for example, 85 to 100% by weight.

The pressure-sensitive adhesive base material may contain a polymerization initiator in addition to a monomer and a crosslinking agent for forming an acrylic polymer. Examples of the polymerization initiator include a photopolymerization initiator and a thermal polymerization initiator. The pressure-sensitive adhesive base material may contain one type of polymerization initiator or two or more types of polymerization initiators.
This polymerization initiator is a polymerization initiator (first polymerization initiator) that constitutes a first trigger when the pressure-sensitive adhesive sheet of the present invention is a hybrid pressure-sensitive adhesive sheet.

Examples of the photopolymerization initiator include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-diphenylethan-1-one. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of benzoin photopolymerization initiators include benzoin. Examples of benzyl photopolymerization initiators include benzil. Examples of benzophenone photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, and polyvinylbenzophenone. Examples of ketal photopolymerization initiators include benzil dimethyl ketal. Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

The amount of the photopolymerization initiator used is not particularly limited, but is preferably 0.001 to 1 part by weight, and more preferably 0.01 to 0.50 parts by weight, per 100 parts by weight of all acrylic polymer monomer units (total amount of monomer components constituting the acrylic polymer).

Examples of thermal polymerization initiators include azo polymerization initiators, peroxide polymerization initiators, and redox polymerization initiators. Examples of azo polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis(2,4,4-trimethylpentane). Examples of peroxide polymerization initiators include benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane.

The amount of the thermal polymerization initiator used is not particularly limited, but is preferably 0.05 to 0.5 parts by weight, and more preferably 0.1 to 0.3 parts by weight, per 100 parts by weight of all monomer units of the acrylic polymer (total amount of monomer components constituting the acrylic polymer).

The adhesive base material may optionally contain additives such as crosslinking accelerators, silane coupling agents, tackifying resins, antioxidants, fillers, colorants such as pigments and dyes, antioxidants, chain transfer agents, plasticizers, softeners, and surfactants. Examples of tackifying resins include rosin derivatives, polyterpene resins, petroleum resins, and oil-soluble phenols.

When the additive described below is an ultraviolet absorber, it is preferable that the adhesive base material does not contain, or substantially does not contain, an ultraviolet absorber. This configuration is preferable in that it minimizes deterioration of curing properties and differences in physical properties between the front and back when the adhesive sheet of the present invention is subjected to the adhesive layer curing process described below. When the proportion of ultraviolet absorber in the total amount (100% by mass) of the adhesive base material is 0.05% by weight or less (preferably 0.01% by mass or less), it can be said that the adhesive base material does not substantially contain an ultraviolet absorber.

Furthermore, when the additive described below is a rust inhibitor, it is preferable that the pressure-sensitive adhesive base material does not contain, or substantially does not contain, a rust inhibitor. This configuration is preferable in that it minimizes the effect of the rust inhibitor on the adhesive layer of the pressure-sensitive adhesive sheet of the present invention. When the proportion of the rust inhibitor in the total amount (100% by mass) of the pressure-sensitive adhesive base material is 0.05% by weight or less (preferably 0.01% by mass or less), it can be said that the pressure-sensitive adhesive base material does not substantially contain a rust inhibitor.

Furthermore, when the additive described below is an antistatic agent, it is preferable that the PSA base material does not contain, or substantially does not contain, an antistatic agent. This configuration is preferable in that it minimizes the effect of the antistatic agent on the PSA layer of the PSA sheet of the present invention. When the proportion of the antistatic agent in the total amount (100% by mass) of the PSA base material is 0.05% by weight or less (preferably 0.01% by mass or less), it can be said that the PSA base material does not substantially contain an antistatic agent.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, but examples include coating (applying) the pressure-sensitive adhesive base material onto a support and drying and curing the resulting pressure-sensitive adhesive composition layer, or coating (applying) the pressure-sensitive adhesive base material onto a support and irradiating the resulting pressure-sensitive adhesive composition layer with active energy rays to cure it. If necessary, the layer may be further dried by heating.

The adhesive base material can be applied (coated) using known coating methods, such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters.

The drying and curing temperature is preferably 40 to 200°C, more preferably 50 to 180°C, and even more preferably 60 to 170°C. The drying and curing time can be set to an appropriate time, for example, 5 seconds to 20 minutes, preferably 5 seconds to 10 minutes, and more preferably 10 seconds to 5 minutes.

Examples of the active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. The irradiation energy, irradiation time, and irradiation method of the active energy rays are not particularly limited, and can be appropriately set to achieve the desired viscosity and viscoelasticity depending on the thickness of the pressure-sensitive adhesive layer 10, etc.

When the pressure-sensitive adhesive layer formed as described above is photocured by irradiation with the above-mentioned active energy rays and/or ultraviolet light described below, it is preferable that the main surface of the pressure-sensitive adhesive layer not facing the support be further laminated with another support (including a release sheet) to block oxygen, which inhibits photocuring.

Next, the adhesive layer 10 is cured (adhesive layer curing step). In Figure 1(b), 10a represents the cured adhesive layer 10. The method for curing the adhesive layer 10 is not particularly limited, but examples include heating the adhesive layer 10 or curing the adhesive layer 10 by irradiating it with active energy rays. If necessary, the adhesive layer may be further heated and dried. Examples of active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred.

The conditions for curing the pressure-sensitive adhesive layer 10 can be appropriately selected depending on the embodiment so that the pressure-sensitive adhesive layer 10a has desired physical properties.
For example, when the adhesive base material in the adhesive sheet of the present invention is a hybrid adhesive sheet containing the polymerization initiator and the crosslinking agent, the heating temperature, time, or the amount of irradiation of active energy rays can be appropriately set so that the adhesive layer 10a exhibits high fluidity and excellent step absorption properties.

On the other hand, if the additive described below is an ultraviolet absorber, anti-rust agent, or antistatic agent, the heating temperature, time, or amount of active energy ray irradiation can be appropriately set so that the pressure-sensitive adhesive layer 10a exhibits a high elastic modulus and excellent adhesive reliability.

1(b) shows an embodiment in which the adhesive layer 10 is cured by irradiating it with ultraviolet light U. While ultraviolet light may be irradiated directly onto the adhesive layer 10, it is preferable to irradiate it through a support to block oxygen, which inhibits curing by ultraviolet light irradiation. FIG. 1(b) shows an embodiment in which ultraviolet light is irradiated onto the adhesive layer 10 through a support S2. When irradiating ultraviolet light through a support, another support S2 (including a release sheet) is attached to the main surface of the adhesive layer 10 opposite the main surface facing the support S1, and ultraviolet light is irradiated through the support. The illuminance and duration of ultraviolet light irradiation are appropriately determined depending on the composition of the adhesive base material, the thickness of the adhesive layer, and other factors. A high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, or the like can be used for ultraviolet light irradiation.

Next, as shown in FIG. 1(c), after peeling and removing the support S2, a solution 12 of additive 11 is applied to one side of the adhesive layer 10a (solution application process). The additive solution is not particularly limited as long as it is liquid and can be applied to and penetrate the adhesive layer. For example, if the additive is liquid, the additive itself may be applied as a solution. Alternatively, a solution in which the additive is dissolved in a solvent may be applied. Alternatively, if the additive is a combination of two or more types (for example, a second polymerization initiator as a second trigger and a second crosslinking agent), a solution in which these are mixed may be applied. FIG. 1(c) shows an embodiment in which a solution 12 in which the additive 11 is dissolved in a solvent 13 is applied to one side of the adhesive layer 10a.

Additive 11 in solution 12 penetrates the surface of adhesive layer 10a in the thickness direction into adhesive layer 10a (solution penetration process). This state is shown in Figure 1(d). When solution 12 is a solution in which additive 11 is dissolved in solvent 13, solvent 13 penetrates and swells the surface of adhesive layer 10a, and additive 11, dissolved in the solvent, penetrates into adhesive layer 10a. Additive 11 becomes "dissolved" within adhesive layer 10a.

Furthermore, as the additive 11 penetrates the adhesive layer 10a, a concentration gradient may form in the thickness direction. Therefore, the concentration of the additive 11 on the side where the solution 12 is applied may be higher than on the opposite side. This state is shown in Figure 1(d).

Then, by drying the adhesive layer 10a, the adhesive sheet 1 shown in Figure 1(e) can be obtained (drying process). If the solution 12 is a solution in which the additive 11 is dissolved in the solvent 13, the permeated solvent 13 evaporates during the drying process. By drying the adhesive layer 10a, the adhesive layer 10a returns to a state close to that before application. Therefore, changes in the physical properties of the adhesive layer 10a due to the additive 11 can be minimized. Once the adhesive layer 10a is dried, the permeation of the additive 11 into the adhesive layer 10a stops, and the concentration gradient of the additive is fixed.

The additives can be any additive commonly used in the field of adhesives, and include, without limitation, polymerization initiators, crosslinking agents, UV absorbers, rust inhibitors, antistatic agents, crosslinking accelerators, silane coupling agents, tackifying resins, antioxidants, colorants such as dyes, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, etc. From the perspective of easily achieving the desired effects of the present invention, polymerization initiators, crosslinking agents, UV absorbers, rust inhibitors, and antistatic agents are preferred.

Note that acids are not preferred as additives. In other words, acids are excluded from the additives. Examples of such acids include organic acids such as acetic acid, propionic acid, and lactic acid, particularly lactic acid.

Examples of polymerization initiators and crosslinking agents include the same polymerization initiators and crosslinking agents that may be contained in the above-mentioned adhesive base material, and these may be used alone or in combination of two or more.

When the pressure-sensitive adhesive sheet of the present invention is a hybrid pressure-sensitive adhesive sheet, the pressure-sensitive adhesive base material contains a first polymerization initiator and a first crosslinking agent as a first trigger, the pressure-sensitive adhesive layer curing process is curing by reaction between the first polymerization initiator and the first crosslinking agent, and additive 11 is at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent as a second trigger.

After the pressure-sensitive adhesive layer curing process, both or either the first polymerization initiator and the first crosslinking agent may remain. In such cases, only either the second polymerization initiator or the second crosslinking agent can be used as additive 11. However, it is also possible to use both the second polymerization initiator and the second crosslinking agent as additives.

When the pressure-sensitive adhesive sheet of the present invention is a hybrid pressure-sensitive adhesive sheet, the degree of freedom in the combination of the first trigger and the second trigger is extremely wide. That is, there are no restrictions on the combination of polymerization initiators. For example, a combination in which both the first trigger and the second trigger are photopolymerization initiators, a combination in which the first trigger is a thermal polymerization initiator and the second trigger is a photopolymerization initiator, or a combination in which the first trigger is a photopolymerization initiator and the second trigger is a thermal polymerization initiator can be freely selected. Furthermore, a combination in which both the first trigger and the second trigger are thermal polymerization initiators, which was difficult with conventional hybrid pressure-sensitive adhesive sheets, is also possible. Furthermore, when both the first trigger and the second trigger are photopolymerization initiators, it is also possible for the light absorption wavelength bands of the two photopolymerization initiators to overlap or be similar. Furthermore, a combination of the same polymerization initiator (whether a thermal polymerization initiator or a photopolymerization initiator) as the first trigger and the second trigger, which was impossible with conventional hybrid pressure-sensitive adhesive sheets, is also possible.
Furthermore, there is no limitation on the combination of crosslinking agents, and it is also possible to combine the same crosslinking agent as the first trigger and the second trigger.

The UV absorber is not particularly limited, but examples include triazine-based UV absorbers, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, oxybenzophenone-based UV absorbers, salicylic acid ester-based UV absorbers, and cyanoacrylate-based UV absorbers. These may be used alone or in combination of two or more. Among these, triazine-based UV absorbers, benzotriazole-based UV absorbers, and benzophenone-based UV absorbers are preferred. At least one UV absorber selected from the group consisting of triazine-based UV absorbers having two or less hydroxyl groups per molecule, and benzotriazole-based UV absorbers and benzophenone-based UV absorbers having one benzotriazole skeleton per molecule is preferred because of its good solubility and high UV absorption ability at wavelengths around 380 nm.

Specific examples of triazine-based ultraviolet absorbers having two or less hydroxyl groups in one molecule include 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN460, manufactured by BASF), 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C ₁₀ -C ₁₆ (mainly C ₁₂ -C ₁₃ ) alkyloxy) methyl] oxirane (TINUVIN 400, manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethoxy)- Examples of suitable phenols include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-glycidic acid ester reaction products (TINUVIN 405, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (TINUVIN 1577, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADK STAB LA46, manufactured by ADEKA), and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN 479, manufactured by BASF).

Furthermore, examples of benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton per molecule include 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C _7-9 side chain and straight chain alkyl) ester compound (TINUVIN 384-2, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 900, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 (TINUVIN 1130, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN P, manufactured by BASF), 2(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 234, manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN 326, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN 328, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN N329, manufactured by BASF), a reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN 213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.).

Furthermore, examples of the benzophenone-based UV absorbers (benzophenone-based compounds) and oxybenzophenone-based UV absorbers (oxybenzophenone-based compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone (Seesorb 106, manufactured by Shipro Chemical Co., Ltd.), and 2,2'-dihydroxy-4,4-dimethoxybenzophenone.

Furthermore, examples of the salicylate ester-based ultraviolet absorbers (salicylate ester-based compounds) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl-2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN 120, manufactured by BASF).

Examples of the cyanoacrylate-based ultraviolet absorber (cyanoacrylate-based compound) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

The maximum absorption wavelength in the absorption spectrum of the ultraviolet absorber is preferably in the wavelength range of 300 to 400 nm, and more preferably in the wavelength range of 320 to 380 nm. When multiple absorption maxima exist in the spectroscopic absorption spectrum in the wavelength range of 300 to 460 nm, the maximum absorption wavelength refers to the absorption maximum wavelength that shows the greatest absorbance among them.

When the additive is at least one selected from a polymerization initiator and a crosslinking agent, it is also preferable that the additive further contains an ultraviolet absorber. By including an ultraviolet absorber in addition to at least one selected from a polymerization initiator and a crosslinking agent, a hybrid pressure-sensitive adhesive sheet containing the ultraviolet absorber can be produced with a single coating step, improving production efficiency. Furthermore, when a hybrid pressure-sensitive adhesive sheet containing the ultraviolet absorber is irradiated with ultraviolet light, the ultraviolet absorber absorbs the ultraviolet light and generates heat, accelerating the curing reaction and improving adhesion reliability, which is even more preferable.

The rust inhibitor is not particularly limited, but examples include benzotriazole compounds and amine compounds. Other examples include ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, dicyclohexylamine benzoate, urea, urotropine, thiourea, phenyl carbamate, and cyclohexylammonium N-cyclohexylcarbamate (CHC). Rust inhibitors can be used alone or in combination of two or more.

Examples of the benzotriazole-based compounds include alkylbenzotriazoles having 1 to 6 carbon atoms, such as benzotriazole (1,2,3-benzotriazole), 4-methylbenzotriazole, 5-methylbenzotriazole, 4-ethylbenzotriazole, 5-ethylbenzotriazole, 4-propylbenzotriazole, 5-propylbenzotriazole, 4-isopropylbenzotriazole, 5-isopropylbenzotriazole, 4-n-butylbenzotriazole, 5-n-butylbenzotriazole, 4-isobutylbenzotriazole, 5-isobutylbenzotriazole, 4-pentylbenzotriazole, 5-pentylbenzotriazole, 4-hexylbenzotriazole, and 5-hexylbenzotriazole; 5-methoxybenzotriazole; Examples of suitable benzotriazoles include benzotriazole, 1-hydroxybenzotriazole, 5-hydroxybenzotriazole, dihydroxypropylbenzotriazole, carboxybenzotriazole, 2,3-dicarboxypropylbenzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, 1-[maleic acid]benzotriazole, 4-chlorobenzotriazole, 5-chlorobenzotriazole, 4-nitrobenzotriazole, 5-nitrobenzotriazole, benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole isopropylamine salt, and methylbenzotriazole cyclohexylamine salt.

Examples of the amine compound include hydroxyl group-containing amine compounds such as 2-amino-2-methyl-1-propanol, monoethanolamine, monoisopropanolamine, diethylethanolamine, ammonia, and aqueous ammonia; cyclic amines such as morpholine; cyclic alkylamine compounds such as cyclohexylamine; and linear alkylamines such as 3-methoxypropylamine.

The antistatic agent is not particularly limited, but is preferably an ionic compound containing a fluorine-containing anion from the viewpoints of compatibility with the acrylic polymer and transparency of the pressure-sensitive adhesive layer. Examples of the ionic compound containing a fluorine-containing anion include _LiCF3SO3 , Li(CF3SO2) _2N , Li( _C2F5SO2 ) _2N , Li( _C4F9SO2 ) _2N , _and Li( _{CF3SO2 ) 3C .} Fluorine-containing _{lithium imide salts such as Li(CF3SO2)2N, Li(C2F5SO2)2N, Li(C4F9SO2)2N , and Li ( FSO2 ) 2N are preferred ,} with bis( _{trifluoromethanesulfonyl} )imide lithium salt and bis(fluorosulfonyl)imide lithium salt being particularly preferred. The antistatic agents may be used alone or in combination _of two or _more .

The solvent is not particularly limited as long as it can dissolve the additive and swell the adhesive layer 10a. However, since aqueous solvents have poor wettability to the adhesive layer and the additives do not easily penetrate, non-aqueous solvents are preferred. Non-aqueous solvents include, but are not limited to, esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alicyclic ketones such as cyclopentanone and cyclohexanone; aliphatic hydrocarbons such as hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as chloroform, dichloromethane, and 1,2-dichloroethane; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; nitriles such as acetonitrile, propionitrile, and benzonitrile; and alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol. Esters, aromatic hydrocarbons, ketones, and alcohols are preferred. These solvents can be used alone or in combination.

The concentration of the additive in the solution can be appropriately set depending on the desired properties to be imparted to the adhesive layer 10a. For example, it can be selected from 95% by weight or less (e.g., 0.1-95% by weight, 0.1-90% by weight, 0.1-85% by weight, 0.1-80% by weight, 0.1-70% by weight, 0.1-60% by weight, 0.1-50% by weight, 0.1-40% by weight, etc.), or 0.1% by weight or more (e.g., 0.1-95% by weight, 0.2-95% by weight, 0.3-95% by weight, 0.4-95% by weight, 0.5-95% by weight, 1-95% by weight, 1.5-95% by weight, 3-95% by weight, 5-95% by weight, etc.). A concentration of the additive in the solution within this range dissolves the additive and sufficiently swells the adhesive layer 10a, imparting the desired properties to the adhesive layer 10a.

Specifically, when the additive is a crosslinking agent, the concentration of the crosslinking agent in the solution can be appropriately set depending on the desired curing properties to be imparted to the pressure-sensitive adhesive layer 10a, and can be appropriately selected from the range of, for example, 95% by weight or less (e.g., 1 to 95% by weight, 1 to 90% by weight, 1 to 85% by weight, 1 to 80% by weight, 1 to 60% by weight, etc.), or, for example, 1% by weight or more (e.g., 1 to 95% by weight, 2 to 95% by weight).
Furthermore, when the additive is an ultraviolet absorber, the concentration of the ultraviolet absorber in the solution can be appropriately set depending on the desired ultraviolet absorption properties to be imparted to the pressure-sensitive adhesive layer 10a, and can be selected from a range, for example, with an upper limit of 50% by weight or less (e.g., 1 to 50% by weight, 1 to 45% by weight, 1 to 40% by weight, 1 to 35% by weight, 1 to 30% by weight, 1 to 25% by weight, 1 to 20% by weight, 1 to 15% by weight, etc.) or a lower limit of 1% or more (e.g., 1 to 50% by weight, 2 to 50% by weight, 3 to 50% by weight, 4 to 50% by weight, 5 to 50% by weight).
Furthermore, when the additive is a rust inhibitor, the concentration of the rust inhibitor in the solution can be set appropriately depending on the desired rust-preventing properties to be imparted to the pressure-sensitive adhesive layer 10a, and can be selected from a range, for example, with an upper limit of 10% by weight or less (e.g., 0.1 to 10% by weight, 0.1 to 9% by weight, 0.1 to 8% by weight, 0.1 to 7% by weight, 0.1 to 6% by weight, 0.1 to 5% by weight, 0.1 to 4% by weight, etc.) or a lower limit of 0.1% or more (e.g., 0.1 to 10% by weight, 0.2 to 10% by weight, 0.3 to 10% by weight, 0.4 to 10% by weight, 0.5 to 10% by weight).
Furthermore, when the additive is an antistatic agent, the concentration of the antistatic agent in the solution can be appropriately set depending on the desired antistatic properties to be imparted to the pressure-sensitive adhesive layer 10a, and can be selected from a range, for example, with an upper limit of 95% by weight or less (e.g., 0.1 to 90% by weight, 0.1 to 9% by weight, 0.1 to 85% by weight, 0.1 to 80% by weight, 0.1 to 75% by weight, 0.1 to 70% by weight, etc.) or a lower limit of 0.1% or more (e.g., 0.1 to 90% by weight, 0.2 to 90% by weight, 0.3 to 90% by weight, 0.4 to 90% by weight, 0.5 to 90% by weight, 0.6 to 90% by weight, 1 to 90% by weight, etc.).
If the concentration of each of the above additives (crosslinking agent, ultraviolet absorber, rust inhibitor, antistatic agent) is higher than the above range, the additives may bleed out or distribution variations may occur in terms of coating uniformity. Also, if the concentration is lower than the above range, more solvent than necessary may be required, which may result in a decrease in adhesive properties due to residual solvent or excessive swelling of the adhesive, resulting in appearance defects (surface irregularities).

The solution 12 can be applied (coated) to the adhesive layer 10a using known coating methods, such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, or direct coater.

The amount of the additive solution applied to the pressure-sensitive adhesive layer 10a can be appropriately set depending on the desired properties to be imparted to the pressure-sensitive adhesive layer 10a, and can be selected, for example, from the range of 1 to 1000 μg/cm ² , preferably 1 to 500 μg/cm ² , more preferably 1 to 300 μg/cm ² , and even more preferably 1 to 100 μg/cm ^2. When the amount of the additive solution applied is within this range, the additive can be dissolved while imparting sufficient required properties to the pressure-sensitive adhesive layer 10a.

After applying the additive solution to the adhesive layer 10a, it may be left to stand, if necessary, to allow the additive to penetrate. There are no particular limitations on the standing time, and it can be selected appropriately, for example, from within 15 minutes, and can be selected from the range of 1 second to 10 minutes, preferably 5 seconds to 5 minutes. The standing time can be room temperature (approximately 10 to 30°C). When left standing under the above conditions, the additive can be sufficiently penetrated into the adhesive layer 10a.

The heating and drying temperature in the drying step is preferably 40 to 200°C, more preferably 50 to 180°C, and even more preferably 60 to 170°C. The drying time can be appropriately set, but is, for example, 5 seconds to 20 minutes, preferably 5 seconds to 10 minutes, and more preferably 10 seconds to 5 minutes. By drying under the above conditions, the pressure-sensitive adhesive layer 10a can be restored to a state close to that before application.
If necessary, a standing time may be provided to further homogenize the additive and the pressure-sensitive adhesive layer. The standing time is not particularly limited and can be appropriately selected, for example, within 30 days, and can be appropriately selected, for example, between 1 hour and 15 days, preferably between 24 hours and 10 days. By standing, the additive and the pressure-sensitive adhesive layer in the pressure-sensitive adhesive layer 10a are stabilized, and variation in characteristic evaluation can be suppressed.

Figure 2(a) is a cross-sectional view showing one embodiment of the adhesive sheet according to the third aspect of the present invention, and Figure 2(b) is a cross-sectional view showing another embodiment of the adhesive sheet according to the third aspect of the present invention.

Referring to Figure 2(a), an adhesive sheet 2A according to one embodiment of the present invention is composed of an optically transparent adhesive layer 21 and a support S1 consisting of a release sheet attached to the other second main surface 21b of the adhesive layer 21, with no support attached to the first main surface 21a of the adhesive layer 21.

Referring to Figure 2(b), an adhesive sheet 2B according to one embodiment of the present invention is composed of an optically transparent adhesive layer 21, a first support S2 consisting of a release sheet bonded to one first main surface 21a of the adhesive layer 21, and a second support S1 consisting of a release sheet bonded to the other second main surface 21b of the adhesive layer 21. The adhesive sheet 2B can be obtained by bonding the support S2 to the first main surface 21a of the adhesive sheet 2A.

In Figures 2(a) and (b), the dotted line X-X' is a line that divides the adhesive layer 21 into two equal parts in the thickness direction. If the thickness of the adhesive layer 21 is not uniform, the dotted line X-X' is a line that divides the thickness at each point into two equal parts.

In Figure 2, adhesive layer 21 is a single layer made of a transparent adhesive base material and having two opposing main surfaces (a first main surface and a second main surface). Adhesive layer 21 can be formed by the adhesive layer formation process and adhesive layer curing process described above, and corresponds to adhesive layer 10a in Figure 1. Therefore, adhesive layer 21 is preferably a cured adhesive layer.

When we say that an adhesive layer is a "single layer," we mean that it is not a laminated structure. For example, forming an adhesive layer made of a transparent adhesive base material, and then forming another adhesive layer made of the same transparent adhesive base material on top of that, is a laminated structure, not a single layer. Similarly, forming an adhesive layer made of a transparent adhesive base material with an additive dissolved in it, and then forming another adhesive layer made of a transparent adhesive base material with an additive dissolved in a different concentration on top of that, is a laminated structure, not a single layer.

The thickness of the adhesive layer 21 is not particularly limited, but is typically 5 μm to 500 μm, preferably 5 μm to 400 μm, and more preferably 5 μm to 350 μm. A thickness of the adhesive layer 21 within this range is suitable for forming a concentration gradient of the additive in the thickness direction of the adhesive layer 21.

The total light transmittance of the entire pressure-sensitive adhesive layer 21 is not particularly limited, but is preferably 80% or more, and more preferably 90% or more, as measured in accordance with JIS K7361. The higher the total light transmittance of the pressure-sensitive adhesive layer 21, the better. Furthermore, the haze value is preferably 1.5% or less, and more preferably 1% or less.

Additive 11 is dissolved in the pressure-sensitive adhesive layer 21. Here, "dissolved" means, for example, that the additive is dissolved to an extent that the transparency of the pressure-sensitive adhesive layer can be maintained, i.e., to an extent that cloudiness due to light scattering by the additive does not occur. Specifically, it is preferable that the additive is contained in the pressure-sensitive adhesive layer so that the haze value of the pressure-sensitive adhesive layer is 1.5% or less, preferably 1% or less.

Additive 11 is formed by penetrating additive 11 into adhesive layer 21 through the solution application process, solution penetration process, and drying process, which can create a concentration gradient of additive 11 in the thickness direction of adhesive layer 21, as shown in Figure 2. Therefore, when a single adhesive layer 21 is divided into two equal parts in the thickness direction, the concentration of additive in the region containing first main surface 21a, one of the two main surfaces, will be different from the concentration of additive in the region containing second main surface 21b. Cases where no additive is present in the region with the lower additive concentration (additive concentration is 0) are also within the scope of the present invention.

The concentration of the additive in the region to which the first principal surface belongs and the concentration of the additive in the region to which the second principal surface belongs shall mean the average concentration of the additive in each region if there is a concentration gradient within each region.

Figure 2(a) shows an embodiment in which the second main surface 21b faces the support S1, and the concentration of the additive in the region to which the first main surface 21a belongs is higher than the concentration of the additive in the region to which the second main surface 21b belongs. This can be obtained by applying a solution of the additive to the first main surface 21a and allowing the additive to penetrate in a dissolved state into the adhesive layer 21 from the first main surface 21a to a depth in the thickness direction.

In the adhesive sheet of the third aspect of the present invention, additives such as rust inhibitors and antistatic agents are distributed at high concentrations near the first main surface 21a, as shown in Figure 2, thereby imparting the required additive properties, such as rust prevention and antistatic properties, to the first main surface 21a. Meanwhile, the concentration of additive 11 throughout the adhesive layer 21 can be reduced, thereby reducing changes in the physical properties of the adhesive layer 21 caused by additive 11.

The pressure-sensitive adhesive sheet of the third aspect of the present invention can be used to bond transparent optical components to other optical components in image display devices such as liquid crystal image display devices and organic EL image display devices. Examples of such optical components include polarizing films, retardation films, transparent cover materials such as cover glass, and various other transparent optical components. Glass substrates on which a transparent conductive layer such as a patterned ITO film is formed can also be included in the optical components of the present invention. The pressure-sensitive adhesive sheet of the third aspect of the present invention can also be suitably used as a surface protection film to prevent scratches and dirt from adhering to the optical components.

Figure 3 is a cross-sectional view of an optical component laminate showing an example of the simplest embodiment using a pressure-sensitive adhesive sheet according to the present invention. Referring to Figure 3, the optical component laminate 3 comprises an optically transparent first optical component 31 and a second optical component 32 bonded to the first optical component 31 via an optically transparent pressure-sensitive adhesive layer 21. The optical component laminate 3 is formed by peeling the supports S1 and S2 from the pressure-sensitive adhesive sheet 2B shown in Figure 2(b) and bonding the first and second optical components. The transparent first optical component 31 and second optical component 32 can be composed of a polarizing film, a retardation film, or other optical film used in optical display devices, or a transparent cover member such as a viewer-side cover glass of an optical display device. The first optical component 31 is bonded to the first major surface 21a of the pressure-sensitive adhesive layer 21, and the second optical component 32 is bonded to the second major surface 21b of the pressure-sensitive adhesive layer 21.

Figure 4 is a diagram schematically illustrating steps for carrying out one embodiment of the method for manufacturing an optical component laminate according to the second aspect of the present invention. In this embodiment, as shown in Figure 4(a), a substrate 42 (hereinafter sometimes simply referred to as "substrate 42") consisting of an adhesive sheet 2C and an optical component is used.

In this embodiment, adhesive sheet 2C is a hybrid adhesive sheet produced by the method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention, and specifically, produced by the following method.
forming a pressure-sensitive adhesive layer on a support, the pressure-sensitive adhesive layer being formed from a transparent pressure-sensitive adhesive base material containing a first polymerization initiator and a first crosslinking agent;
curing the pressure-sensitive adhesive layer by a reaction between the first polymerization initiator and the first crosslinking agent;
preparing a solution of at least one additive selected from the group consisting of a second polymerization initiator and a second crosslinking agent;
applying the solution to one surface of the cured pressure-sensitive adhesive layer, and allowing the additive contained in the solution to penetrate the pressure-sensitive adhesive layer from the one surface in a thickness direction;
The adhesive layer is dried.

In the adhesive sheet 2C of Figure 4(a), in this embodiment, the pressure-sensitive adhesive layer 41 is cured by the reaction of the first polymerization initiator and the first cross-linking agent (not shown), and the second polymerization initiator 11a and the second cross-linking agent 11b are dispersed in a dissolved state. The present invention also encompasses embodiments in which only either the second polymerization initiator 11a or the second cross-linking agent 11b is dissolved in the pressure-sensitive adhesive layer 41.

In this embodiment, the adhesive sheet 2C has a support S3, but the support S3 is not necessary. In this embodiment, a concentration gradient of the second polymerization initiator 11a and the second cross-linking agent 11b exists in the thickness direction from the main surface 41a where the pressure-sensitive adhesive layer 41 contacts the support S3.

In this embodiment, the main surface 42a of the substrate 42 in Figure 4(a) that is bonded to the adhesive sheet 2C has a printed layer 43. Examples of the printed layer 43 include a transparent, conductive printed layer made of patterned ITO (indium tin oxide), or a black concealing portion formed in a frame shape around the periphery of the transparent cover member. The present invention also encompasses the use of a substrate 42 that does not have a printed layer 43.

Next, the adhesive layer 41 of the adhesive sheet 2C is bonded to the main surface 42a of the substrate 42. Bonding can be performed by known methods, such as using an autoclave under heat and pressure. The adhesive layer 41 of the adhesive sheet 2C is cured by the reaction between the first polymerization initiator and the first crosslinking agent (first trigger), but is in a state prior to the curing reaction of at least one agent (second trigger) selected from the group consisting of the second polymerization initiator 11a and the second crosslinking agent 11b, exhibiting high fluidity and excellent level difference absorption properties. Therefore, the adhesive layer 41 is bonded so as to completely fill the level difference between the main surface 42a of the substrate 42 and the printed layer 43.

Next, the adhesive layer 41 is cured by a reaction of at least one agent (second trigger) selected from the group consisting of a second polymerization initiator 11a and a second crosslinking agent 11b. The method for curing the adhesive layer 41 is not particularly limited as long as the curing reaction proceeds due to the second trigger. Examples of the method include heating the adhesive layer 41 or irradiating the adhesive layer 41 with active energy rays to cure it. If necessary, the adhesive layer may be further heated and dried. Examples of active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred.

The conditions for curing the adhesive layer 41 can be appropriately set, for example, by setting the heating temperature, time, or amount of active energy radiation exposure so as to achieve a high elastic modulus and excellent adhesive reliability.

Figure 4(c) shows an embodiment in which the adhesive layer 41 is irradiated with ultraviolet light U to cure the adhesive layer 41. Irradiation with ultraviolet light U decomposes the second polymerization initiator 11a, generating radicals or ions, which initiate the polymerization/crosslinking reaction of the second crosslinking agent 11b. The adhesive layer 41 may be irradiated with ultraviolet light directly or via the support S3. Figure 4(c) shows an embodiment in which the adhesive layer 41 is irradiated with ultraviolet light U via the support S3. When ultraviolet light is irradiated directly to the adhesive layer 41, the support S3 may be peeled off from the adhesive layer 41 before irradiating the adhesive layer 41 with ultraviolet light U.

By curing the adhesive layer 41, the optical component laminate 4 is obtained as shown in FIG. 4(d). In FIG. 4(d), 41c denotes the adhesive layer 41 after curing. The optical component laminate 4 is an embodiment showing an example of the optical component laminate according to the fourth aspect of the present invention.

By curing the adhesive layer 41, the crosslinking agent 11b crosslinks and polymerizes to form a crosslinked structure 11c, forming the adhesive layer 41c. The adhesive layer 41c has an improved elastic modulus and improved adhesion reliability to the substrate 42. Therefore, the adhesive layer 41c suppresses the generation of gases such as carbon dioxide when the substrate 42 (plastic film) is heated, preventing the generation of air bubbles.

4(d), the crosslink density is higher on the main surface 41a where the pressure-sensitive adhesive layer 41c contacts the support S3 than on the opposite main surface 41b. This configuration is preferable in that it can improve flexibility when the optical component laminate 4 is used as a flexible image display device in which the main surface 41a side is bent outward.
That is, when a flexible display is bent, a tensile stress is generally applied to the outside and a compressive stress is applied to the inside, with the stress on the outside being stronger than the stress on the inside. Therefore, by arranging the main surface 41 a of the adhesive layer 41 c on the outside when the flexible display is bent, durability against bending can be improved.

In this embodiment, the optical member laminate 4 has, for example, the following configuration.
An optical member laminate 4 including a substrate 42 made of an optical member and a pressure-sensitive adhesive layer 41c,
The pressure-sensitive adhesive layer 41c is laminated on a main surface of the substrate 43 made of the optical member,
the pressure-sensitive adhesive layer 41c is a single layer having two opposing main surfaces and made of a transparent pressure-sensitive adhesive base material cured by a reaction between the first polymerization initiator and the first crosslinking agent (first trigger) and a reaction with at least one agent (second trigger) selected from the group consisting of the second polymerization initiator 11a and the second crosslinking agent 11b;
When the single-layer adhesive layer is divided into two equal parts in the thickness direction, the density of the cross-linked structure 11c in the region to which the first main surface 41a, one of the two main surfaces, belongs is different from the density of the cross-linked structure 11c in the region to which the second main surface 41b, the other main surface, belongs.

In this embodiment, the adhesive layer 41c is laminated so as to fill the gap between the main surface 42a of the substrate 42 and the printing layer 43.

The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

(Preparation of Pressure-Sensitive Adhesive Sheet A)
A monomer mixture consisting of 66 parts by weight of 2-ethylhexyl acrylate (2EHA), 19 parts by weight of 2-hydroxyethyl acrylate (HEA), and 15 parts by weight of N-vinyl-2-pyrrolidone (NVP) was blended with 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 184", manufactured by BASF Corporation) and 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 651", manufactured by BASF Corporation), and then irradiated with ultraviolet light until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa s, thereby obtaining a prepolymer composition in which a portion of the monomer components was polymerized.

Next, 0.2 parts by weight of hexanediol diacrylate (HDDA) was added to and mixed with the prepolymer composition to obtain an acrylic pressure-sensitive adhesive composition. The acrylic pressure-sensitive adhesive composition was applied to the release-treated surface of a release film (trade name "MRF#38", manufactured by Mitsubishi Plastics, Inc.) so that the thickness after formation of the pressure-sensitive adhesive layer would be 100 μm to form a pressure-sensitive adhesive composition layer, and then a release film (trade name "MRN#38", manufactured by Mitsubishi Plastics, Inc.) was attached to the surface of the pressure-sensitive adhesive composition layer. Thereafter, ultraviolet light was irradiated under conditions of illuminance: 5 mW/cm ² and light quantity: 1500 mJ/cm ² to photocure the pressure-sensitive adhesive composition layer, thereby forming a pressure-sensitive adhesive sheet A.

(Preparation of Pressure-Sensitive Adhesive Sheet B)
A pressure-sensitive adhesive sheet B was formed in the same manner as pressure-sensitive adhesive sheet A, except that the amount of hexanediol diacrylate (HDDA) added was 0.1 parts by weight.

(Preparation of Pressure-Sensitive Adhesive Sheet C)
A pressure-sensitive adhesive sheet C was formed in the same manner as pressure-sensitive adhesive sheet A, except that 96 parts by weight of butyl acrylate (BA) and 4 parts by weight of acrylic acid (AA) were used as the monomer mixture, 0.1 parts by weight of 2-hydroxyethyl acrylate (HEA) was used instead of hexanediol diacrylate (HDDA), and the thickness of the pressure-sensitive adhesive layer after formation was 23 μm.

(Preparation of Pressure-Sensitive Adhesive Sheet D)
A pressure-sensitive adhesive sheet D was formed in the same manner as pressure-sensitive adhesive sheet A, except that 57 parts by weight of butyl acrylate (BA), 23 parts by weight of 4-hydroxybutyl acrylate (4HBA), 8 parts by weight of 2-hydroxyethyl acrylate (HEA), and 12 parts by weight of cyclohexyl acrylate (CHA) were used as the monomer mixture, 0.02 parts by weight of dipentaerythritol hexaacrylate (DPHA) was used instead of hexanediol diacrylate (HDDA), and the thickness after pressure-sensitive adhesive layer formation was 150 μm.

(Preparation of Pressure-Sensitive Adhesive Sheet E)
A pressure-sensitive adhesive sheet E was formed in the same manner as pressure-sensitive adhesive sheet A, except that 29 parts by weight of 2-ethylhexyl acrylate (2EHA), 21 parts by weight of 4-hydroxybutyl acrylate (4HBA), 29 parts by weight of isostearyl acrylate (ISTA), and 21 parts by weight of isobornyl acrylate (IBXA) were used as the monomer mixture.

(Preparation of Pressure-Sensitive Adhesive Sheet F)
A pressure-sensitive adhesive sheet F was formed in the same manner as pressure-sensitive adhesive sheet A, except that 41 parts by weight of 2-ethylhexyl acrylate (2EHA), 1 part by weight of 4-hydroxybutyl acrylate (4HBA), 17 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 41 parts by weight of isostearyl acrylate (ISTA) were used as the monomer mixture, and 0.02 parts by weight of trimethylolpropane triacrylate (TMPTA) was used instead of hexanediol diacrylate (HDDA).

(Preparation of Pressure-Sensitive Adhesive Sheet G)
A pressure-sensitive adhesive sheet G was formed in the same manner as pressure-sensitive adhesive sheet A, except that 57 parts by weight of butyl acrylate (BA), 23 parts by weight of 4-hydroxybutyl acrylate (4HBA), 8 parts by weight of 2-hydroxyethyl acrylate (HEA), and 12 parts by weight of cyclohexyl acrylate (CHA) were used as the monomer mixture, 0.03 parts by weight of dipentaerythritol hexaacrylate (HEA) was used instead of hexanediol diacrylate (HDDA), and the thickness after pressure-sensitive adhesive layer formation was 250 μm.

Example 1
The release film on one main surface (referred to as the "first surface") of PSA sheet A was peeled off, and a 10 wt% ethyl acetate solution of an ultraviolet absorber (Tinosorb S, manufactured by BASF) was coated onto the exposed first surface using a No. 7 Wire Wound Rod type bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After coating, the PSA sheet A was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, yielding a PSA sheet A comprising a PSA layer in which the ultraviolet absorber was dissolved.

(Comparative Example 1)
The release film on the first surface of the pressure-sensitive adhesive sheet A was peeled off, and the pressure-sensitive adhesive sheet A to which the ultraviolet absorber solution was not applied was used as Comparative Example 1.

Example 2
An adhesive sheet B including an adhesive layer in which the ultraviolet absorber (Tinuvin 928, manufactured by BASF) was dissolved was obtained in the same manner as in Example 1, except that an ethyl acetate solution with a concentration of 12 wt % was applied to the adhesive sheet B.

Example 3
An adhesive layer B containing a dissolved ultraviolet absorber was obtained in the same manner as in Example 1, except that an ultraviolet absorber (Tinuvin 928, manufactured by BASF) solution having a concentration of 12 wt% in methyl ethyl ketone was applied using adhesive sheet B.

Example 4
An adhesive sheet B including an adhesive layer in which an ultraviolet absorber (Seesorb 106, manufactured by Shipro Kasei Co., Ltd.) was dissolved was obtained in the same manner as in Example 1, except that an ethyl acetate solution with a concentration of 15 wt % was applied to the adhesive sheet B.

(Comparative Example 2)
The release film on the first surface of the adhesive sheet B was peeled off, and the adhesive sheet B to which the ultraviolet absorber solution was not applied was used as Comparative Example 2.

Example 5
A pressure-sensitive adhesive sheet C including a pressure-sensitive adhesive layer having a dissolved ultraviolet absorber (Tinosorb S, manufactured by BASF) was obtained in the same manner as in Example 1, except that pressure-sensitive adhesive sheet C was used.

Example 6
An adhesive sheet C including an adhesive layer in which an ultraviolet absorber was dissolved was obtained in the same manner as in Example 1, except that an ethyl acetate solution with a concentration of 12 wt % of an ultraviolet absorber (Tinuvin 928, manufactured by BASF) was applied to the adhesive sheet C.

Example 7
An adhesive sheet C including an adhesive layer in which an ultraviolet absorber was dissolved was obtained in the same manner as in Example 1, except that a 12 wt% solution of an ultraviolet absorber (Tinuvin 928, manufactured by BASF) in methyl ethyl ketone was applied using the adhesive sheet C.

(Example 8)
An adhesive sheet C including an adhesive layer in which an ultraviolet absorber (Seesorb 106, manufactured by Shipro Kasei Co., Ltd.) was dissolved was obtained in the same manner as in Example 1, except that an ethyl acetate solution with a concentration of 15 wt % was applied to the adhesive sheet C.

(Comparative Example 3)
The release film on the first surface of the pressure-sensitive adhesive sheet C was peeled off, and the pressure-sensitive adhesive sheet C to which the ultraviolet absorber solution was not applied was used as Comparative Example 3.

(Comparative Example 4)
A pressure-sensitive adhesive sheet C containing no ultraviolet absorber was obtained in the same manner as in Example 1, except that the pressure-sensitive adhesive sheet C was used and ethyl acetate containing no ultraviolet absorber was applied.

Example 9
A pressure-sensitive adhesive sheet D including a pressure-sensitive adhesive layer having a dissolved ultraviolet absorber (Tinosorb S, manufactured by BASF) was obtained in the same manner as in Example 1, except that pressure-sensitive adhesive sheet D was used.

(Comparative Example 5)
The release film on the first surface of the pressure-sensitive adhesive sheet D was peeled off, and the pressure-sensitive adhesive sheet D to which the ultraviolet absorber solution was not applied was used as Comparative Example 5.

Example 10
A pressure-sensitive adhesive sheet E including a pressure-sensitive adhesive layer having a dissolved ultraviolet absorber (Tinosorb S, manufactured by BASF) was obtained in the same manner as in Example 1, except that pressure-sensitive adhesive sheet E was used.

(Comparative Example 6)
The release film on the first surface of the pressure-sensitive adhesive sheet F was peeled off, and a pressure-sensitive adhesive sheet E was obtained without applying the ultraviolet absorber solution, which was designated as Comparative Example 6.

Example 11
A pressure-sensitive adhesive sheet F including a pressure-sensitive adhesive layer having a dissolved ultraviolet absorber (Tinosorb S, manufactured by BASF) was obtained in the same manner as in Example 1, except that pressure-sensitive adhesive sheet F was used.

(Comparative Example 7)
The release film on the first surface of the pressure-sensitive adhesive sheet F was peeled off, and the pressure-sensitive adhesive sheet F to which the ultraviolet absorber solution was not applied was used as Comparative Example 7.

(Comparative Example 8)
A pressure-sensitive adhesive sheet F containing no ultraviolet absorber was obtained in the same manner as in Example 1, except that pressure-sensitive adhesive sheet F was used and ethyl acetate containing no ultraviolet absorber was applied.

(Comparative Example 9)
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the ultraviolet absorber was uniformly dissolved was obtained in the same manner as for pressure-sensitive adhesive sheet D, except that 70 parts by weight of butyl acrylate (BA), 14 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 16 parts by weight of N-vinyl-2-pyrrolidone (NVP) were used as the monomer mixture, and 0.0009 parts by weight of an ultraviolet absorber (Tinosorb S, manufactured by BASF) was further blended into the acrylic pressure-sensitive adhesive composition.

<Transmittance evaluation>
The release films were peeled off from the pressure-sensitive adhesive sheets obtained in Examples 1 to 11 and Comparative Examples 1 to 8, and the light transmittance at each wavelength (wavelength range: 300 to 800 nm) was evaluated using a spectrophotometer (U4100, manufactured by Hitachi High-Tech Science Corp.). The transmittances (%) at 380 nm and 420 nm are shown in Table 1.

<Adhesion strength evaluation>
The release films were peeled off from the pressure-sensitive adhesive sheets obtained in Examples 1 to 11 and Comparative Examples 1 to 8. The surface on which the ultraviolet absorber solution was applied was designated the first surface, and the opposite main surface was designated the second surface.
The resulting adhesive sheet was cut to a width of 100 mm and a length of 100 mm, and the first or second side was laminated to alkali glass, and a PET film (thickness: 25 μm) was laminated to the opposite side. The laminate was then laminated using a hand roller and heated and pressurized in an autoclave for 15 minutes (5 atm, 50 °C). The adhesive strength (N/10 mm) of the resulting sample was measured using an autograph (pulling speed: 60 mm/min, peel angle: 180 °). Three samples were prepared for each condition, and the number average value was taken. The adhesive strength (N/10 mm) of the first and second sides to alkali glass and the difference between them are shown in Table 1.

Table 1 shows that applying a solution of UV absorber to the adhesive layer of a UV-cured adhesive sheet can impart excellent UV absorption properties to the adhesive layer. Furthermore, the difference in adhesive strength between the first and second sides of the adhesive layer was 1.0 N/mm, indicating that applying a solution of UV absorber to the adhesive layer of a cured adhesive sheet can minimize differences in physical properties such as adhesive strength between the front and back of the adhesive layer.

<Evaluation of UV absorber distribution in the thickness direction of the adhesive>
TOF-SIMS analysis (Ar gas cluster ion etching method) was performed to examine the distribution state of the ultraviolet absorber (Tinosorb S) in the thickness direction of Example 9 and Comparative Example 9. The samples used were stored for one month after production.
The release films were peeled off from the pressure-sensitive adhesive sheets obtained in Example 9 and Comparative Example 9, and TOF-SIMS analysis was performed from the first surface side under the following measurement conditions. The results are shown in Figure 5. Figure 5(a) shows the results for Example 9, and Figure 5(b) shows the results for Comparative Example 9. In Figure 5, the scale on the left vertical axis shows the intensity of butyl acrylate (BA, _C3 + _H3 + _O2 ) and N-vinylpyrrolidone (NVP, _C4 + _H6 + N + O), and the scale on the right vertical axis shows the intensity of the ultraviolet absorber (Tinosorb S, _C30 + _H32 + _N3 + _O5 ).

Analysis equipment: TOF-SIMS (ULVAC-PHI, TRIFT V)
Etching ions: Ar gas cluster ions Irradiated primary ions: Bi ₃ ²⁺
Acceleration voltage: 30 kV
Measurement polarity: negative ions

Figure 5(a) shows that the adhesive layer of the adhesive sheet of Example 9 has a concentration gradient of the ultraviolet absorber (Tinosorb S) from the first side to the second side. On the other hand, Figure 5(b) shows that the adhesive layer of the adhesive sheet of Comparative Example 9 has the ultraviolet absorber (Tinosorb S) distributed at a constant concentration from the first side to the second side.

Example 12
The release film on one main surface (referred to as the "first surface") of the pressure-sensitive adhesive sheet A was peeled off, and an ethyl acetate solution containing 20 wt% hexanediol diacrylate (HDDA) and 1 wt% photopolymerization initiator (Omnirad 184, manufactured by IGM Resins B.V.) diluted to a concentration of 1 wt% was applied to the exposed first surface using a wire wound rod type #7 bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After application, the pressure-sensitive adhesive sheet A was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, thereby obtaining a pressure-sensitive adhesive sheet A including a pressure-sensitive adhesive layer in which HDDA was dissolved.

Example 13
A pressure-sensitive adhesive sheet B including a pressure-sensitive adhesive layer having HDDA dissolved therein was obtained in the same manner as in Example 12, except that pressure-sensitive adhesive sheet B was used.

Example 14
An adhesive sheet G including an adhesive layer in which DPHA was dissolved was obtained in the same manner as in Example 12, except that an ethyl acetate solution containing 5 wt % dipentaerythritol hexaacrylate (DPHA) and 0.25 wt % photopolymerization initiator (Omnirad 184, manufactured by IGM Resins B.V.) diluted to a concentration of 5 wt % was applied to the adhesive sheet G.

Example 15
An adhesive sheet G including an adhesive layer in which HDDA was dissolved was obtained in the same manner as in Example 12, except that an ethyl acetate solution diluted with 2 wt % hexanediol diacrylate (HDDA) and 0.1 wt % photopolymerization initiator (Omnirad 184, manufactured by IGM Resins B.V.) was applied to the adhesive sheet G.

Example 16
An adhesive sheet G including an adhesive layer in which HDDA was dissolved was obtained in the same manner as in Example 12, except that an ethyl acetate solution containing 40 wt % hexanediol diacrylate (HDDA) and 2 wt % photopolymerization initiator (Omnirad 184, manufactured by IGM Resins B.V.) was applied to the adhesive sheet G.

(Example 17)
An adhesive sheet G including an adhesive layer in which TMPTA was dissolved was obtained in the same manner as in Example 12, except that an ethyl acetate solution containing 5 wt % of trimethylolpropane triacrylate (TMPTA) and 0.25 wt % of the photopolymerization initiator Omnirad 184 (manufactured by IGM Resins B.V.) was applied to the adhesive sheet G.

<Elasticity Modulus Evaluation>
The release films were peeled off from the pressure-sensitive adhesive sheets obtained in Examples 12 to 17, and the pressure-sensitive adhesive layers were laminated to a thickness of approximately 2 mm to prepare measurement samples. Dynamic viscoelasticity measurements were carried out under the following conditions using an Advanced Rheometric Expansion System (ARES) manufactured by Rheometric Scientific.
(Measurement conditions)
Deformation mode: Torsion Measurement frequency: 1 Hz
Heating rate: 5°C/min. Shape: parallel plate 7.9mmφ

The measurement sample was then cured by irradiating it with ultraviolet light at an illuminance of 300 mW/ ^cm2 and an integrated light quantity of 3,000 mJ/ ^cm2 , and the dynamic viscoelasticity was measured by the method described above. Table 2 shows the storage modulus at 85°C before and after curing.

In Examples 12 to 17, the storage modulus was improved by applying a crosslinker solution to the adhesive layer and subjecting the dried adhesive sheets A, B, and G to curing conditions. Therefore, the adhesive sheets of Examples 12 to 17 are useful as hybrid adhesive sheets. Furthermore, Examples 15 and 16 also demonstrate that the storage modulus after curing can be controlled by adjusting the concentration of the crosslinker solution.

(Example 18)
The release film on one main surface (referred to as the "first side") of the pressure-sensitive adhesive sheet C was peeled off, and a 0.5 wt% ethanol solution of a rust inhibitor (1,2,3-benzotriazole) was coated onto the exposed first side using a Wire Wound Rod type #7 bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After coating, the pressure-sensitive adhesive sheet C was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, yielding a pressure-sensitive adhesive sheet C comprising a pressure-sensitive adhesive layer in which the rust inhibitor was dissolved.

(Comparative Example 10)
The release film on the first surface of the adhesive sheet C was peeled off, and the adhesive sheet C to which the rust inhibitor solution was not applied was used as Comparative Example 10.

<Evaluation of rust prevention function>
The release films were peeled off from the pressure-sensitive adhesive sheets obtained in Example 18 and Comparative Example 10. The surface coated with the rust inhibitor solution was designated the first side, and the opposite main surface was designated the second side. The obtained pressure-sensitive adhesive sheets were cut to a width of 100 mm and a length of 100 mm, and the first or second side was attached to a copper-plated film, and a PET film (thickness: 25 μm) was attached to the opposite side. The sheets were then laminated using a hand roller, and heated and pressurized in an autoclave (5 atm, 50° C.) for 15 minutes. The copper-coated film used was a cycloolefin film (trade name "ZEONOR (registered trademark) ZF16, thickness 50 μm) with hard coat layers formed on both sides and a 50 nm copper layer formed on one side by sputtering (surface resistance value: 0.58 Ω/□). This was stored in an environment of 85°C and 85% RH for 500 hours, and the state of the copper was evaluated before and after storage. The surface resistance value of the copper was measured using a Hall hardness measurement device (Accent Optical Technologies HL5500PC). In addition, the copper surface was visually observed to evaluate the presence or absence of corrosion. After storage, the presence or absence of the rust inhibitor was confirmed using a microscope. The results are shown in Table 3.

Table 3 shows that applying a rust inhibitor solution to the adhesive layer can impart rust prevention properties to the adhesive. Furthermore, the surface resistance value after 500 hours on the first side, on which the rust inhibitor solution was applied, was lower than on the second side, suggesting that there is a difference in the concentration of the rust inhibitor between the front and back surfaces.

Example 19
The release film on one main surface (referred to as the "first surface") of the pressure-sensitive adhesive sheet C was peeled off, and a 5 wt% ethanol solution of an antistatic agent (lithium bis(trifluoromethanesulfonyl)imide) was coated onto the exposed first surface using a Wire Wound Rod type #7 bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After coating, the pressure-sensitive adhesive sheet C was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, yielding a pressure-sensitive adhesive sheet C comprising a pressure-sensitive adhesive layer in which the antistatic agent was dissolved.

(Example 20)
A pressure-sensitive adhesive sheet C including a pressure-sensitive adhesive layer having an antistatic agent dissolved therein was obtained in the same manner as in Example 19, except that the concentration of the antistatic agent solution was 10 wt %.

(Example 20)
A pressure-sensitive adhesive sheet C including a pressure-sensitive adhesive layer having an antistatic agent dissolved therein was obtained in the same manner as in Example 19, except that the concentration of the antistatic agent solution was set to 20 wt %.

(Comparative Example 11)
The release film on the first surface of the adhesive sheet C was peeled off, and the adhesive sheet C to which the antistatic agent solution was not applied was used as Comparative Example 11.

<Evaluation of antistatic function>
One release film was peeled off from the pressure-sensitive adhesive sheets obtained in Examples 19 to 21 and Comparative Example 11, and the surface resistance of the pressure-sensitive adhesive layer was measured under the following conditions. The main surface coated with the antistatic agent solution was designated the first side, and the opposite main surface was designated the second side. The results are shown in Table 4.
Measuring device: Hiresta MCP-HT450 (Mitsubishi Chemical Analytical)
Probe: URS
Applied voltage: 250V

Table 4 shows that applying an antistatic agent solution to the adhesive layer can impart antistatic properties to the adhesive.

Example 22
The release film on one main surface (referred to as the "first surface") of the pressure-sensitive adhesive sheet B was peeled off, and an ethyl acetate solution containing 10 wt% of an ultraviolet absorber (Tinosorb S, manufactured by BASF), 20 wt% of hexanediol diacrylate (HDDA), and 0.3 wt% of a photopolymerization initiator (Omnirad 819, manufactured by IGM Resins BV) diluted to a concentration of 10 wt% was applied to the exposed first surface using a wire wound rod type bar coater, #7, manufactured by RD Specialties (target wet coating thickness: 15 μm). After application, the pressure-sensitive adhesive sheet B was heated and dried in an oven at 110 ° C. for 2 minutes to volatilize and remove the solvent, thereby obtaining a pressure-sensitive adhesive sheet B containing the ultraviolet absorber and a pressure-sensitive adhesive layer in which HDDA was dissolved.

(Example 23)
A pressure-sensitive adhesive sheet B comprising a pressure-sensitive adhesive layer in which the ultraviolet absorber (Tinuvin 928, manufactured by BASF) was dissolved and HDDA was obtained in the same manner as in Example 22, except that an ethyl acetate solution diluted to a concentration of 12 wt % of an ultraviolet absorber, 30 wt % of hexanediol diacrylate (HDDA), and 0.5 wt % of a photopolymerization initiator (Omnirad 819, manufactured by IGM Resins B.V.) was applied.

(Example 24)
An adhesive sheet B including an adhesive layer in which HDDA was dissolved was obtained in the same manner as in Example 22, except that an ethyl acetate solution diluted to a concentration of 20 wt % hexanediol diacrylate (HDDA) and 0.3 wt % photopolymerization initiator (Omnirad 819, manufactured by IGM Resins B.V.) was applied.

Example 25
An adhesive sheet B including an adhesive layer in which HDDA was dissolved was obtained in the same manner as in Example 22, except that an ethyl acetate solution diluted to a concentration of 30 wt % hexanediol diacrylate (HDDA) and 0.5 wt % photopolymerization initiator (Omnirad 819, manufactured by IGM Resins B.V.) was applied.

<Evaluation>
The pressure-sensitive adhesive sheets obtained in Examples 22 to 25 were left to stand for 7 days in the same manner as in Examples 12 to 17, and then evaluated for the above-mentioned "transmittance evaluation,""adhesive strength evaluation," and "elastic modulus evaluation." The transmittance evaluation and adhesive strength evaluation were performed on the pressure-sensitive adhesive sheets before they were cured by ultraviolet irradiation. The results are shown in Table 5.

The adhesive sheets of Examples 22 and 23, which were coated with a solution containing a UV absorber in addition to a photopolymerization initiator and crosslinker, showed a higher storage modulus after curing and improved adhesive reliability compared to the adhesive sheets of Examples 24 and 25, which were coated with a solution that did not contain a UV absorber. This is thought to be because the UV absorber absorbed UV light, generating heat and accelerating the curing reaction.

Variations of the present invention are listed below.
[Appendix 1] A pressure-sensitive adhesive layer made of a transparent pressure-sensitive adhesive base material is formed on a support,
Curing the pressure-sensitive adhesive layer,
Prepare a solution of additives,
applying the solution to one surface of the cured pressure-sensitive adhesive layer, and allowing the additive contained in the solution to penetrate the pressure-sensitive adhesive layer from the one surface in a thickness direction;
A method for producing a pressure-sensitive adhesive sheet, comprising the step of drying the pressure-sensitive adhesive layer.
[Appendix 2] The solution of the additive is a solution in which the additive is dissolved in a solvent,
Attachment 1, the manufacturing method of the pressure-sensitive adhesive sheet, comprising a step of evaporating the solvent of the solution by drying the pressure-sensitive adhesive layer.
[Appendix 3] The method for producing a pressure-sensitive adhesive sheet according to appendix 1 or 2, further comprising the step of attaching a release sheet to the surface of the pressure-sensitive adhesive layer opposite the support.
[Appendix 4] The method for producing a pressure-sensitive adhesive sheet according to any one of Appendices 1 to 3, wherein the additive is at least one selected from the group consisting of a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an antistatic agent.
[Appendix 5] The method for producing a pressure-sensitive adhesive sheet according to Appendix 4, wherein the additive is at least one selected from the group consisting of a polymerization initiator and a crosslinking agent.
[Appendix 6] The method for producing a pressure-sensitive adhesive sheet according to Appendix 5, wherein the additive further comprises an ultraviolet absorber.
[Appendix 7] The pressure-sensitive adhesive base material comprises a first polymerization initiator and a first crosslinking agent,
the curing is caused by a reaction between the first polymerization initiator and the first crosslinking agent,
7. The method for producing a pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the additive is at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent.
[Appendix 8] The method for producing a pressure-sensitive adhesive sheet according to Appendix 7, wherein the first polymerization initiator is the same as the second polymerization initiator.
[Appendix 9] A method for producing an optical member laminate including a substrate made of an optical member and a pressure-sensitive adhesive layer,
A pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet obtained by the method described in Appendix 7 or 8 is bonded to a main surface of a substrate made of the optical member;
a step of curing the pressure-sensitive adhesive layer by a reaction with at least one agent selected from the group consisting of the second polymerization initiator and the second crosslinking agent,
A method for manufacturing an optical member laminate.
[Appendix 10] The main surface of the substrate made of the optical member has a printing layer,
10. The method for producing an optical member laminate according to claim 9, wherein the pressure-sensitive adhesive layer is bonded so as to fill in any step between the main surface of the substrate made of the optical member and the printing layer.
[Appendix 11] A pressure-sensitive adhesive sheet having a support and a transparent pressure-sensitive adhesive layer on the support,
the pressure-sensitive adhesive layer is a single layer made of a transparent pressure-sensitive adhesive base material and having two opposing main surfaces;
an additive dissolved in the pressure-sensitive adhesive layer;
When the single-layer pressure-sensitive adhesive layer is divided into two equal parts in the thickness direction, the concentration of the additive in a region to which a first main surface, one of the two main surfaces, belongs is different from the concentration of the additive in a region to which a second main surface, the other of the two main surfaces, belongs.
[Appendix 12] The pressure-sensitive adhesive sheet according to Appendix 11, wherein the pressure-sensitive adhesive layer is a cured pressure-sensitive adhesive layer.
[Appendix 13] The pressure-sensitive adhesive sheet according to appendix 11 or 12, characterized in that the second main surface faces the support, and the concentration of the additive in the region to which the first main surface belongs is higher than the concentration of the additive in the region to which the second main surface belongs.
[Appendix 14] The pressure-sensitive adhesive sheet according to any one of Appendices 11 to 13, wherein the single-layer pressure-sensitive adhesive layer has a concentration gradient of the additive in the thickness direction.
[Appendix 15] The pressure-sensitive adhesive sheet according to any one of Appendices 11 to 14, wherein the support comprises a release sheet.
[Appendix 16] The pressure-sensitive adhesive sheet according to appendix 15, characterized in that the support made of a release sheet is disposed on both sides of the pressure-sensitive adhesive layer.
[Appendix 17] The pressure-sensitive adhesive sheet according to any one of Appendices 11 to 16, wherein the additive is at least one selected from the group consisting of a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an antistatic agent.
[Appendix 18] The pressure-sensitive adhesive sheet according to Appendix 17, wherein the additive is at least one selected from the group consisting of a polymerization initiator and a crosslinking agent.
[Appendix 19] The pressure-sensitive adhesive sheet according to Appendix 18, wherein the additive further comprises an ultraviolet absorber.
[Appendix 20] The pressure-sensitive adhesive base material comprises a first polymerization initiator and a first crosslinking agent,
the curing is caused by a reaction between the first polymerization initiator and the first crosslinking agent,
20. The pressure-sensitive adhesive sheet according to any one of claims 12 to 19, wherein the additive is at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent.
[Appendix 21] The pressure-sensitive adhesive sheet according to appendix 20, wherein the first polymerization initiator is the same as the second polymerization initiator.
[Appendix 22] The pressure-sensitive adhesive sheet according to any one of Appendices 11 to 21, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 500 μm.
[Appendix 23] A substrate made of an optical member;
An optical member laminate comprising:
the pressure-sensitive adhesive layer is laminated on a main surface of the substrate made of the optical member,
The optical member laminate, wherein the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of appendices 18 to 21.
[Appendix 24] The main surface of the substrate made of the optical member has a printing layer,
24. The optical member laminate described in Appendix 23, wherein the pressure-sensitive adhesive layer is laminated so as to fill in any step between the main surface of the substrate made of the optical member and the printing layer.
[Appendix 25] The optical component laminate according to Appendices 23 or 24, wherein the cured product is a cured product obtained by the reaction of at least one selected from the group consisting of the second polymerization initiator and the second crosslinking agent.

The present invention is useful for a method for producing a pressure-sensitive adhesive sheet having a transparent pressure-sensitive adhesive layer that can be used to bond a transparent optical component to another optical component, and for a pressure-sensitive adhesive sheet obtainable by this method.

10 Adhesive layer (before curing)
10a Adhesive layer (after curing)
S, S1, S2, S3 Support (release sheet)
U: ultraviolet light 11 additive 11a second polymerization initiator 11b second crosslinking agent 11c crosslinked structure 12 additive solution 13 solvent 31, 32 optical member 21 pressure-sensitive adhesive layer (after curing)
21a: Main surface (first surface) of pressure-sensitive adhesive layer
21b Main surface (second surface) of pressure-sensitive adhesive layer
41 Adhesive layer (before curing)
41a: Main surface (first surface) of adhesive layer
41b Main surface (second surface) of pressure-sensitive adhesive layer
42 Optical member 42a Main surface of optical member 43 Printed layer

Claims (24)

forming a pressure-sensitive adhesive layer made of a transparent pressure-sensitive adhesive base material on a support;
Curing the pressure-sensitive adhesive layer,
Prepare a solution of additives,
the additive solution is a solution in which the additive is dissolved in a solvent,
applying the solution to one surface of the cured pressure-sensitive adhesive layer, and allowing the additive contained in the solution to penetrate the pressure-sensitive adhesive layer from the one surface in a thickness direction;
A method for producing a pressure-sensitive adhesive sheet, comprising the step of drying the pressure-sensitive adhesive layer. The method for producing a pressure-sensitive adhesive sheet according to claim 1 , further comprising the step of drying the pressure-sensitive adhesive layer to evaporate the solvent of the solution. The method for manufacturing an adhesive sheet according to claim 1 or 2 further comprises a step of attaching a release sheet to the surface of the adhesive layer opposite the support. The method for producing a pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the additive is at least one selected from the group consisting of a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an antistatic agent. The method for producing a pressure-sensitive adhesive sheet according to claim 4, wherein the additive is at least one selected from the group consisting of a polymerization initiator and a crosslinking agent. The method for producing a pressure-sensitive adhesive sheet according to claim 5, wherein the additive further comprises an ultraviolet absorber. the pressure-sensitive adhesive base material includes a first polymerization initiator and a first crosslinking agent,
the curing is caused by a reaction between the first polymerization initiator and the first crosslinking agent,
The method for producing a pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the additive is at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent. The method for manufacturing a pressure-sensitive adhesive sheet according to claim 7, wherein the first polymerization initiator is the same as the second polymerization initiator. A method for producing an optical member laminate including a substrate made of an optical member and a pressure-sensitive adhesive layer,
A pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet obtained by the method according to claim 7 or 8 is bonded to a main surface of a substrate made of the optical member,
a step of curing the pressure-sensitive adhesive layer by a reaction with at least one agent selected from the group consisting of the second polymerization initiator and the second crosslinking agent,
A method for manufacturing an optical member laminate. a main surface of the substrate made of the optical member has a print layer;
The method for producing an optical member laminate according to claim 9 , wherein the pressure-sensitive adhesive layer is bonded so as to fill a step between the main surface of the substrate made of the optical member and the printed layer. A pressure-sensitive adhesive sheet having a support and a transparent pressure-sensitive adhesive layer on the support,
the pressure-sensitive adhesive layer is a single layer made of a transparent pressure-sensitive adhesive base material and having two opposing main surfaces;
the pressure-sensitive adhesive layer is a cured pressure-sensitive adhesive layer,
an additive dissolved in the pressure-sensitive adhesive layer;
When the single-layer pressure-sensitive adhesive layer is divided into two equal parts in the thickness direction, the concentration of the additive in a region to which a first main surface, one of the two main surfaces, belongs is different from the concentration of the additive in a region to which a second main surface, the other of the two main surfaces, belongs. The adhesive sheet of claim 11, characterized in that the second main surface faces the support and the concentration of the additive in the region to which the first main surface belongs is higher than the concentration of the additive in the region to which the second main surface belongs. The pressure-sensitive adhesive sheet according to claim 11 or 12 , wherein the single pressure-sensitive adhesive layer has a concentration gradient of the additive in the thickness direction. The pressure-sensitive adhesive sheet according to any one of claims 11 to 13 , wherein the support is a release sheet. The pressure-sensitive adhesive sheet according to claim 14 , wherein the support made of a release sheet is disposed on both sides of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to any one of claims 11 to 15 , wherein the additive is at least one selected from the group consisting of a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an anti-static agent. The pressure-sensitive adhesive sheet according to claim 16 , wherein the additive is at least one selected from the group consisting of a polymerization initiator and a crosslinking agent. The pressure-sensitive adhesive sheet according to claim 17 , wherein the additive further comprises an ultraviolet absorber. the pressure-sensitive adhesive base material includes a first polymerization initiator and a first crosslinking agent,
the curing is caused by a reaction between the first polymerization initiator and the first crosslinking agent,
The pressure-sensitive adhesive sheet according to any one of claims 11 to 18 , wherein the additive is at least one selected from the group consisting of a second polymerization initiator and a second crosslinking agent. 20. The pressure-sensitive adhesive sheet according to claim 19 , wherein the first polymerization initiator is the same as the second polymerization initiator. The pressure-sensitive adhesive sheet according to any one of claims 11 to 20 , wherein the pressure-sensitive adhesive layer has a thickness of 5 to 500 µm. a substrate made of an optical member;
An optical member laminate comprising:
the pressure-sensitive adhesive layer is laminated on a main surface of the substrate made of the optical member,
An optical member laminate, wherein the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to claim 19 or 20 . a main surface of the substrate made of the optical member has a print layer;
The optical member laminate according to claim 22 , wherein the pressure-sensitive adhesive layer is laminated so as to fill a step between the main surface of the substrate made of the optical member and the printed layer. 24. The optical member laminate according to claim 22 , wherein the cured product is a product obtained by a reaction of at least one agent selected from the group consisting of the second polymerization initiator and the second crosslinking agent.