Method for manufacturing pressure-sensitive adhesive sheet and pressure-sensitive adhesive sheet

Abstract

To provide a manufacturing method of an adhesive sheet easy to design, enhancing a degree of freedom in design such as a selection of additives or curing conditions, while suppressing a change in physical properties of an adhesive sheet or an interference between additives, even when an additive is mixed in an adhesive sheet, and also to provide an adhesive sheet obtained through the manufacturing method.SOLUTION: A manufacturing method of an adhesive sheet includes steps of: disposing an adhesive layer 10 formed of a transparent adhesive base material on a substrate S; curing the adhesive layer 10; preparing a solution 12 of an additive 11; applying the solution 12 on one surface of the cured adhesive layer 10a; impregnating the additive 11 contained in the solution 12 in a thickness direction from the one surface of the adhesive layer 10a; and drying the adhesive layer 10a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] 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. [Background technology]

[0002] Image display devices such as liquid crystal display devices or organic EL display devices are composed of an optical component laminate in which transparent cover members such as polarizing films, retardation films, and cover glasses, as well as various other transparent optical components, are laminated. An adhesive sheet made of a transparent pressure-sensitive adhesive layer is used to bond these optical components. Specifically, a pressure-sensitive adhesive sheet is placed between two optical components to be bonded, and the two optical components are bonded by pressing them together to form an optical component laminate. Furthermore, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer provided on one side of a substrate film is commonly used as a surface protection film in the manufacturing process of optical products to prevent scratches and dirt from adhering to the optical components.

[0003] The pressure-sensitive adhesive sheet may contain various additives such as a polymerization initiator, a crosslinking agent, an ultraviolet absorber, an anti-rust agent, and an anti-static agent depending on the required properties.

[0004] 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 black frame-shaped 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.

[0005] On the other hand, plastic films used as optical components contain gases such as carbon dioxide, and gas may be generated under high temperature conditions during the manufacturing process. In this case, if the pressure-sensitive adhesive layer is soft, the generation of gas cannot be suppressed, causing the pressure-sensitive adhesive layer to float and generate bubbles. Therefore, in order to suppress the generation of gas from the plastic film, the adhesive sheet is also required to have a high elastic modulus and hardness of the pressure-sensitive adhesive layer, thereby improving adhesion reliability.

[0006] 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") is first used to create a semi-cured state with high fluidity and excellent level difference absorbency, allowing the sheet to fully conform to levels, and then the other trigger (sometimes referred to herein as a "second trigger") completes the curing, thereby improving adhesive reliability.

[0007] Furthermore, image display devices are sometimes required to have UV blocking properties in order to prevent deterioration of components within the image display device due to incident UV rays. In particular, organic EL display devices 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 decreases, making it essential to provide a UV absorbing layer. For example, it is known to use a pressure-sensitive adhesive sheet having a UV absorbing layer containing a UV absorber (see, for example, Patent Document 2).

[0008] Furthermore, as sensors become larger and frames become narrower in image display devices and input devices, there are an increasing number of examples in which copper wiring is provided. Copper has excellent electrical conductivity and is a useful material for wiring, but it has the problem of being susceptible to oxidation and corrosion. It is known to incorporate a rust inhibitor into a pressure-sensitive adhesive sheet in order to suppress the oxidation and corrosion of copper wiring (see, for example, Patent Document 3).

[0009] Furthermore, there is a concern that static electricity generated when peeling a surface protection film from an optical component such as a polarizing film may damage the electrical circuits of the image display device. Furthermore, static electricity may attract dust and reduce workability. For example, it is known to incorporate an antistatic agent into the pressure-sensitive adhesive layer in order to prevent static electricity from being generated by the surface protection film (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. WO2016 / 170875 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-211305 [Patent Document 3] International Publication No. WO2015 / 145767 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-128537 Summary of the Invention [Problem to be solved by the invention]

[0011] When the above-mentioned various additives 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 elastic modulus. In particular, in recent years, as image display devices have become lighter and thinner, pressure-sensitive adhesive layers have become thinner, and there is an increasing demand for higher concentrations of additives in pressure-sensitive adhesive sheets to satisfy the 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.

[0012] Given this background, when blending additives into a pressure-sensitive adhesive sheet, it has become necessary to start from scratch and design the amounts of various additives to be blended, the pressure-sensitive adhesive composition such as the monomer composition of the base polymer, the thickness of the pressure-sensitive adhesive sheet, the curing conditions, etc., in order to not only satisfy the required properties of the additives but also to minimize changes in the physical properties of the pressure-sensitive adhesive sheet, such as adhesive strength and elastic modulus, and to minimize interference between additives. Furthermore, there is the problem that achieving both the required properties of the additives and the physical properties of the pressure-sensitive adhesive sheet limits the degree of freedom in designing additive selection, curing conditions, etc.

[0013] For example, in a hybrid pressure-sensitive adhesive composition, 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 cause the curing reaction caused by the second trigger to proceed, resulting in the problem that the degree of freedom in designing the trigger selection and curing conditions, etc., is extremely limited.

[0014] For example, if the first trigger is a thermal polymerization initiator and the second trigger is a photopolymerization initiator, the second trigger may begin curing during the thermal curing of the first trigger, necessitating strict control of the curing reaction. Furthermore, there is also the problem that thick adhesive layers take a long time to thermally cure, reducing production efficiency. Furthermore, when the first trigger is a photopolymerization initiator and the second trigger is a thermal polymerization initiator, process management 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. 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.

[0015] Furthermore, the incorporation of a sufficient amount of ultraviolet absorber to impart ultraviolet blocking properties to the pressure-sensitive adhesive composition has the problem of affecting the physical properties and curing properties of the pressure-sensitive adhesive. In particular, when a photocurable pressure-sensitive adhesive sheet containing an ultraviolet absorber is cured by ultraviolet irradiation, the ultraviolet light is absorbed by the ultraviolet absorber, which deteriorates the curing properties and reduces productivity.

[0016] Furthermore, photocurable pressure-sensitive adhesive sheets containing ultraviolet absorbers have the problem of differences in physical properties such as adhesiveness and viscoelasticity between the front and back of the pressure-sensitive adhesive sheet. This is because ultraviolet light is absorbed by the ultraviolet absorber as it passes through the pressure-sensitive adhesive layer, and the ultraviolet irradiance decreases with increasing depth from the surface on the ultraviolet-irradiated side, resulting in differences in curing speed between the front and back.

[0017] Furthermore, in the above-mentioned patent documents, additives are blended into the pressure-sensitive adhesive composition and dissolved uniformly, but anti-rust agents, anti-static agents, etc., are originally intended to function only near the interface with the optical member to be bonded. However, in order to impart sufficient anti-rust and anti-static properties to the surface of the pressure-sensitive adhesive sheet, it is necessary to blend the additives into the entire pressure-sensitive adhesive layer, which creates a dilemma in that this affects the physical properties of the pressure-sensitive adhesive sheet.

[0018] The present invention was devised in light of the above circumstances, and aims to provide a method for manufacturing an adhesive sheet that is easy to design by providing a high degree of 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.

[0019] 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. [Means for solving the problem]

[0020]

[0005] As a result of extensive research to achieve the above object, the present inventors have found that by applying and penetrating a solution of an additive into the adhesive layer of a pressure-sensitive adhesive sheet after curing the adhesive layer, the influence on the physical properties of the adhesive layer and the interference between additives can be minimized, resulting in a pressure-sensitive adhesive sheet that has excellent physical properties of the adhesive layer and exhibits the excellent required properties of the additive. Furthermore, they have found that this significantly improves the degree of freedom in designing the additive selection and curing conditions. The present invention was completed based on these findings.

[0021] 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; Drying the adhesive layer The present invention provides a method for producing a pressure-sensitive adhesive sheet, comprising the steps of:

[0022] By curing the pressure-sensitive adhesive layer before incorporating the additive into the pressure-sensitive adhesive layer, the influence of the additive on the pressure-sensitive adhesive layer can be reduced, and therefore, changes in the physical properties of the pressure-sensitive adhesive layer due to the additive can be minimized.

[0023] By applying a solution of the additive to the cured pressure-sensitive adhesive layer, the additive penetrates into the pressure-sensitive adhesive layer. This allows the required properties of the additive to be imparted to the pressure-sensitive adhesive layer. Furthermore, the transparency of the pressure-sensitive adhesive layer is maintained by the additive penetrating in the form of a solution.

[0024] The adhesive layer is then dried by heating or the like. This process returns the adhesive layer to a state close to that before application. That is, 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 application of the solution.

[0025] Because the adhesive layer is cured before the additives are added, once the composition, curing conditions, physical properties, etc. of the adhesive composition are determined, there is no need to redesign the composition due to the addition of additives, and the thickness of the adhesive layer can be easily changed. The required properties imparted to the adhesive layer can then be controlled by changing the coating conditions of the additive solution. In this way, the control of the physical properties of the adhesive layer and the control of the required properties by the additives can be separated, so there is no need to design the adhesive layer from scratch when changing the thickness of the adhesive layer or the amount of additive added, which is efficient.

[0026] In the method for producing 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.

[0027] Furthermore, for example, by separately applying solutions of two or more additives to the adhesive layer and drying them, it is possible to reduce interference between the additives and efficiently impart a variety of required properties.

[0028] The method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention may further comprise the step of attaching a release sheet to the surface of the pressure-sensitive adhesive layer opposite the support, which is preferred in that the surface of the pressure-sensitive adhesive layer can be protected by attaching a release sheet.

[0029] 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.

[0030] 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.

[0031] 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, as a second trigger. The first polymerization initiator may be the same as the second polymerization initiator.

[0032] 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 the hybrid adhesive sheet.

[0033] In other words, because the curing reactions of the first and second triggers are separated, the degree of freedom in selecting the combination of the first and second triggers is extremely high. For example, combinations such as a combination where both the first and second triggers are photopolymerization initiators, a combination where the first trigger is a thermal polymerization initiator and the second trigger is a photopolymerization initiator, or a combination where the first trigger is a photopolymerization initiator and the second trigger is a thermal polymerization initiator can be freely selected. 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 photopolymerization initiators to overlap or be similar.

[0034] Furthermore, it is also possible to combine the same polymerization initiator (whether a thermal polymerization initiator or a photopolymerization initiator) as the first and second triggers, which was not possible with conventional hybrid pressure-sensitive adhesive sheets. In this way, there is an extremely high degree of freedom in the combination of the first trigger and the second trigger, and it is even possible to combine the same triggers, which is also advantageous in that it makes it possible to avoid the use of a polymerization initiator that may cause discoloration or deterioration of the adhesive layer.

[0035] 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 changing the coating conditions and curing conditions of the second trigger solution.

[0036] 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, thereby minimizing reduced productivity 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.

[0037] Furthermore, because the adhesive layer is cured before the addition of the UV absorber, once the composition, curing conditions, physical properties, etc. of the adhesive composition are determined, there is no need to redesign the composition due to the addition of a UV absorber, and the thickness of the adhesive layer can be easily changed. Then, by changing the coating conditions of the UV absorber solution, the UV absorbing function imparted to the adhesive layer can be controlled. In this way, since the control of the physical properties of the adhesive layer and the control of the UV absorbing function can be separated, there is no need to design the adhesive layer from scratch to change the thickness or UV absorbing function of the adhesive layer, which is efficient.

[0038] Furthermore, for example, when an ultraviolet absorber is blended into the hybrid pressure-sensitive adhesive sheet, the ultraviolet absorber can be added after curing by 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, which greatly increases the freedom of selection for the combination of photopolymerization initiator and ultraviolet absorber.

[0039] 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 the additive 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, improving production efficiency. Furthermore, when the 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.

[0040] In the first aspect of the present invention, when the additive is a rust inhibitor or an antistatic agent, a solution of the rust inhibitor or antistatic agent can be applied to and penetrated into the surface of the cured pressure-sensitive adhesive layer, thereby imparting sufficient rust inhibitor or antistatic function to the vicinity of the surface of the pressure-sensitive adhesive layer. Since it is not necessary to uniformly disperse the rust inhibitor or antistatic agent in the pressure-sensitive adhesive layer, changes in physical properties such as the elastic modulus 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.

[0041] Furthermore, because the adhesive layer is cured before the addition of the rust inhibitor or antistatic agent, once the composition, curing conditions, physical properties, etc. of the adhesive composition are determined, there is no need to redesign the composition by adding the rust inhibitor or antistatic agent, and the thickness of the adhesive layer can be easily changed. Then, by changing the coating conditions for the rust inhibitor or antistatic agent solution, the rust prevention function or antistatic ability imparted to the adhesive layer can be controlled. In this way, since the control of the physical properties of the adhesive layer and the control of the rust prevention function or antistatic ability by the rust inhibitor or antistatic agent can be separated, there is no need to design 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.

[0042] 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.

[0043] 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.

[0044] A second aspect of the present invention is a method for producing an optical member 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 agent (second trigger) selected from the group consisting of a second polymerization initiator and a second crosslinking agent. 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 gap.

[0045] Next, by curing the pressure-sensitive adhesive layer through a reaction with at least one (second trigger) selected from the group consisting of the second polymerization initiator and the second crosslinking agent, the elastic modulus of the pressure-sensitive adhesive layer can be increased, thereby improving adhesion reliability.

[0046] 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; When the single layer of adhesive layer is divided into two equal parts in the thickness direction, The adhesive sheet is characterized in that the concentration of the additive in the region to which the first main surface, one of the two main surfaces, belongs is different from the concentration of the additive in the region to which the other second main surface belongs.

[0047] The pressure-sensitive adhesive sheet according to the third aspect of the present invention can be obtained by the pressure-sensitive adhesive sheet manufacturing method according to 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 generated between the front and back of the pressure-sensitive adhesive layer. As described above, a pressure-sensitive adhesive sheet that can have this configuration can minimize changes in physical properties due to the additive.

[0048] In the method for producing a pressure-sensitive adhesive sheet according to the first aspect of the present invention, the concentration of the additive may be the same or substantially the same on both sides of the pressure-sensitive adhesive layer depending on conditions such as the thickness of the pressure-sensitive adhesive layer and the penetration time of the additive. Thus, 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.

[0049] In the pressure-sensitive adhesive sheet according to the third aspect of the present invention, the pressure-sensitive adhesive layer is preferably a cured pressure-sensitive adhesive layer, which is preferable in that changes in physical properties due to additives can be minimized.

[0050] In the pressure-sensitive adhesive sheet according to the third aspect of the present invention, it is preferred 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.

[0051] In the pressure-sensitive adhesive sheet according to the third aspect of the present invention, the single pressure-sensitive adhesive layer preferably has a concentration gradient of the additive in the thickness direction, which 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.

[0052] In the pressure-sensitive adhesive sheet according to the third aspect of the present invention, the support is preferably 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. The support being a release sheet is preferable in that it can be bonded to a transparent optical component after being peeled off.

[0053] In the pressure-sensitive adhesive sheet according to 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 preferred examples for achieving the desired effects of the present invention.

[0054] 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.

[0055] 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.

[0056] 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, as a second trigger. The first polymerization initiator may be the same as the second polymerization initiator.

[0057] When the third aspect of the present invention is a hybrid pressure-sensitive adhesive sheet, it can achieve the same effects as when the first aspect of the present invention is a method for producing a hybrid pressure-sensitive adhesive sheet. Furthermore, by making the concentration of the second trigger in the region to which the first principal surface belongs different from the concentration of the second trigger in the region to which the second principal surface belongs, it is possible to control the crosslinking density between the first principal surface and the second principal 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 stress on the outside being stronger than the stress on the inside. Therefore, by placing the side of the pressure-sensitive adhesive layer with a higher concentration of the second trigger on the outside when the flexible display is bent, it is possible to improve durability against bending.

[0058] When the additive in the pressure-sensitive adhesive sheet of the third aspect of the present invention is an ultraviolet absorber, it can achieve the same effects as when the additive is an ultraviolet absorber in the method for producing a pressure-sensitive adhesive sheet of the first aspect of the present invention. That is, 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.

[0059] 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 effect as when the additive is a rust inhibitor or antistatic agent in the method for producing a pressure-sensitive adhesive sheet of the first aspect of the present invention can be achieved. 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.

[0060] In the pressure-sensitive adhesive sheet according to 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.

[0061] 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.

[0062] 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.

[0063] In addition, in a fourth aspect of the present invention, The cured product is preferably a product cured by a reaction of at least one selected from the group consisting of the second polymerization initiator and the second crosslinking agent.

[0064] 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. [Effects of the Invention]

[0065] 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. [Brief explanation of the drawings]

[0066] [Figure 1] 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. [Figure 2] 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. [Figure 3] FIG. 3 is a cross-sectional view of an optical member laminate showing an example of the simplest embodiment using a pressure-sensitive adhesive sheet according to the present invention. [Figure 4] FIG. 4 is a schematic diagram showing steps for carrying out one embodiment of a method for producing an optical member laminate using a hybrid adhesive sheet of the present invention. [Figure 5] 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). DETAILED DESCRIPTION OF THE INVENTION

[0067] 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).

[0068] 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.

[0069] 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, an appropriate material can be selected from acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. From the viewpoints of transparency, processability, and durability, it is preferable to use an acrylic adhesive. 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 of 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 the same applies to other cases. In the present 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.

[0070] When the PSA base material contains an acrylic polymer that is an acrylic PSA, the acrylic polymer preferably contains, as the main monomer unit in the largest amount by weight, a monomer unit derived from an acrylic acid alkyl ester having a linear or branched alkyl group and / or a methacrylic acid alkyl ester having a linear or branched alkyl group.

[0071] Examples of the (meth)acrylic acid alkyl ester having a linear or branched alkyl group to form the monomer unit of the acrylic polymer, i.e., the (meth)acrylic acid alkyl ester having a linear or branched alkyl group contained in the monomer component to form the acrylic polymer, include 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, 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 for the acrylic polymer is preferably at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and isostearyl acrylate.

[0072] The proportion of monomer units derived from a (meth)acrylic acid alkyl ester 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. That is, the proportion of a (meth)acrylic acid alkyl ester in the monomer component composition of the raw material for forming 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.

[0073] 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.

[0074] The proportion of the monomer unit derived from the alicyclic monomer in the acrylic polymer is preferably 5 to 60% by weight, more preferably 10 to 50% by weight, and more preferably 12 to 40% by weight, from the viewpoint of realizing appropriate flexibility in the adhesive base material formed containing the acrylic polymer.

[0075] The acrylic polymer contained in the PSA base material may contain a monomer unit derived from a hydroxyl group-containing monomer. The hydroxyl group-containing monomer is a monomer having at least one hydroxyl group in 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 have adhesive properties and appropriate cohesive strength. In addition, the hydroxyl group can also serve as a reaction site with the crosslinking agent described below.

[0076] Hydroxyl-containing monomers for forming the monomer units of the acrylic polymer, i.e., hydroxyl-containing monomers contained in the monomer components for forming the acrylic polymer, include, for example, hydroxyl-containing (meth)acrylic esters, vinyl alcohol, and allyl alcohol. Examples of hydroxyl-containing (meth)acrylic 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-containing monomer for the acrylic polymer, one type of hydroxyl-containing monomer may be used, or two or more types of hydroxyl-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.

[0077] The proportion of monomer units derived from hydroxyl group-containing monomers in the acrylic polymer is preferably 1 wt% or more, more preferably 2 wt% or more, more preferably 3 wt% or more, more preferably 7 wt% or more, more preferably 10 wt% or more, more preferably 15 wt% or more. The proportion of monomer units derived from hydroxyl group-containing monomers in the acrylic polymer is preferably 35 wt% or less, more preferably 30 wt% or less. These configurations regarding the proportion of hydroxyl group-containing monomers are suitable for achieving adhesiveness and appropriate cohesive strength in a pressure-sensitive adhesive base material formed containing the acrylic polymer.

[0078] The acrylic polymer contained in the PSA base material may contain a monomer unit derived from a nitrogen atom-containing monomer. The nitrogen atom-containing monomer is a monomer that has at least one nitrogen atom in 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 have hardness and good adhesive reliability.

[0079] The nitrogen atom-containing monomer for forming the monomer unit of the acrylic polymer, i.e., the nitrogen atom-containing monomer contained in the monomer component for forming the acrylic polymer, can be, for example, N-vinyl cyclic amides and (meth)acrylamides. Examples of the N-vinyl cyclic amide as the nitrogen atom-containing monomer 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, Nn-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.

[0080] The proportion of the nitrogen-atom-containing monomer-derived monomer unit 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 realizing appropriate hardness, adhesiveness, and transparency in the pressure-sensitive adhesive base material formed containing the acrylic polymer. Also, the proportion of the nitrogen-atom-containing monomer-derived monomer unit in the acrylic polymer is preferably 30% by weight or less, more preferably 25% by weight or less, from the viewpoint of realizing sufficient transparency in the pressure-sensitive adhesive base material formed containing the acrylic polymer and realizing good adhesion reliability by preventing the material from becoming too hard.

[0081] The acrylic polymer contained in the PSA base material may contain a monomer unit derived from a carboxyl group-containing monomer. The carboxyl group-containing monomer is a monomer having at least one carboxyl group within the monomer unit. When the acrylic polymer in the PSA base material contains a carboxyl group-containing monomer unit, the PSA base material may achieve good adhesive reliability. Furthermore, the carboxyl group can also serve as a reaction site with the crosslinking agent described below.

[0082] Examples of the carboxyl group-containing monomer for forming the monomer unit of the acrylic polymer, i.e., the carboxyl group-containing monomer contained in the monomer component for forming the acrylic polymer, include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. As the carboxyl group-containing monomer for the acrylic polymer, one type of carboxyl group-containing monomer may be used, or two or more types of carboxyl group-containing monomers may be used. In this embodiment, acrylic acid is preferably used as the carboxyl group-containing monomer for the acrylic polymer.

[0083] The proportion of the monomer units derived from carboxyl group-containing monomers in the acrylic polymer is preferably 0.1 wt% or more, more preferably 0.5 wt% 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 the interaction between polar groups and carboxyl groups when polar groups are present on the adherend surface. Also, the proportion of the monomer units derived from carboxyl group-containing monomers in the acrylic polymer is preferably 20 wt% or less, more preferably 15 wt% or less, from the viewpoint of preventing the pressure-sensitive adhesive base material formed containing the acrylic polymer from becoming too hard and realizing good adhesive reliability.

[0084] The acrylic polymer contained in the adhesive base material may have a crosslinked structure derived from a crosslinking agent. When the adhesive base material has a crosslinked structure, the viscosity increases, shape stability improves, and it becomes easier to form an adhesive layer on the support S1. Examples of crosslinking agents include polyfunctional (meth)acrylates and thermosetting crosslinking agents, which are copolymerizable crosslinking agents. The acrylic polymer may have a crosslinked structure derived only from a polyfunctional (meth)acrylate, a crosslinked structure derived only 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.

[0085] 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 the polyfunctional (meth)acrylate 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, as the polyfunctional (meth)acrylate for the acrylic polymer, at least one selected from the group consisting of 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, and trimethylolpropane triacrylate is preferably used.

[0086] The proportion of the monomer unit derived from the polyfunctional (meth)acrylate in the acrylic polymer is preferably 0.01 wt% or more, more preferably 0.03 wt% or more, more preferably 0.05 wt% or more, more preferably 0.1 wt% or more. The proportion of the monomer unit derived from the polyfunctional (meth)acrylate in the acrylic polymer is preferably 1 wt% or less, more preferably 0.5 wt% or less. These configurations regarding the proportion of the polyfunctional (meth)acrylate are suitable for realizing appropriate hardness, adhesiveness, and shape stability in a pressure-sensitive adhesive base material formed containing the acrylic polymer.

[0087] 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.

[0088] 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. Further, examples of the isocyanate crosslinking agent 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.).

[0089] Examples of epoxy crosslinking agents (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. Further, examples of the epoxy crosslinking agent include epoxy resins having two or more epoxy groups. In addition, examples of the epoxy crosslinking agent include commercially available products such as "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0090] When the PSA base material contains the above-described thermosetting crosslinking agent for crosslinking between acrylic polymers, the content of the thermosetting crosslinking agent in the PSA 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 PSA base material, from the viewpoints of improving the shape stability of the PSA base material, facilitating the formation of a PSA layer on the support S1, and achieving sufficient adhesive reliability to the adherend. Furthermore, the content of the thermosetting crosslinking agent in the PSA 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 PSA base material, from the viewpoints of imparting appropriate flexibility to the PSA base material and achieving good adhesive strength.

[0091] When the pressure-sensitive adhesive base material contains the above-mentioned acrylic polymer as a pressure-sensitive adhesive, the content of the acrylic polymer in the pressure-sensitive adhesive base material is, for example, 85 to 100 wt %.

[0092] 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.

[0093] 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-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of benzoin-based photopolymerization initiators include benzoin. Examples of benzyl-based photopolymerization initiators include benzil. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, and polyvinylbenzophenone. Examples of ketal-based 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.

[0094] 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 monomer units of the acrylic polymer (total amount of monomer components constituting the acrylic polymer).

[0095] Examples of the thermal polymerization initiator include azo-based polymerization initiators, peroxide-based polymerization initiators, redox-based polymerization initiators, etc. Examples of the azo-based polymerization initiator 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), 2,2'-azobis(2,4,4-trimethylpentane), etc. 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.

[0096] 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, relative to 100 parts by weight of all monomer units of the acrylic polymer (total amount of monomer components constituting the acrylic polymer).

[0097] The PSA base material may further contain, as necessary, additives such as a crosslinking accelerator, a silane coupling agent, a tackifying resin, an antioxidant, a filler, a colorant such as a pigment or dye, an antioxidant, a chain transfer agent, a plasticizer, a softener, a surfactant, etc. Examples of tackifying resins include rosin derivatives, polyterpene resins, petroleum resins, and oil-soluble phenols.

[0098] When the additive described below is an ultraviolet absorber, the adhesive base material preferably does not contain or substantially does not contain an ultraviolet absorber. Such a configuration is preferable in that it can minimize deterioration of curing properties and differences in physical properties between the front and back sides when the adhesive sheet of the present invention is subjected to the adhesive layer curing step described below. When the proportion of the 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.

[0099] Furthermore, when the additive described below is a rust inhibitor, it is preferable that the PSA base material does not contain or substantially does not contain a rust inhibitor. Such a configuration is preferable in that it can minimize the effect of the rust inhibitor on the PSA layer of the PSA sheet of the present invention. When the proportion of the rust inhibitor in the total amount (100 mass%) of the PSA base material is 0.05 wt% or less (preferably 0.01 mass% or less), it can be said that the PSA base material does not substantially contain a rust inhibitor.

[0100] 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. Such a configuration is preferable in that it can minimize 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.

[0101] The method for forming the pressure-sensitive adhesive layer is not particularly limited, but examples thereof include coating (applying) the pressure-sensitive adhesive base material onto a support, 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.

[0102] The adhesive base material can be applied (coated) using a known coating method, for example, a coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or a direct coater.

[0103] 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 appropriately selected from among various times, and is, for example, 5 seconds to 20 minutes, preferably 5 seconds to 10 minutes, and more preferably 10 seconds to 5 minutes.

[0104] Examples of the active energy rays include ionizing radiation such as α-rays, β-rays, γ-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 may be appropriately set to achieve the desired viscosity and viscoelasticity depending on the thickness of the pressure-sensitive adhesive layer 10, etc.

[0105] When the pressure-sensitive adhesive layer formed 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 not facing the support is further laminated with another support (including a release sheet) to block oxygen, which inhibits photocuring.

[0106] Next, the pressure-sensitive adhesive layer 10 is cured (pressure-sensitive adhesive layer curing step). In FIG. 1(b), 10a denotes the pressure-sensitive adhesive layer 10 after curing. The method for curing the pressure-sensitive adhesive layer 10 is not particularly limited, but examples thereof include heating the pressure-sensitive adhesive layer 10 and curing the pressure-sensitive adhesive layer 10 by irradiating it with active energy rays. If necessary, the pressure-sensitive adhesive layer 10 may be further heated and dried. Examples of active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred.

[0107] 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.

[0108] On the other hand, when the additive described below is an ultraviolet absorber, an anti-rust agent, or an anti-static agent, the heating temperature, time, or the amount of irradiation with active energy rays may be appropriately set so that the adhesive layer 10a exhibits a high elastic modulus and excellent adhesive reliability.

[0109] FIG. 1(b) shows an embodiment in which the pressure-sensitive adhesive layer 10 is irradiated with ultraviolet light U to cure the pressure-sensitive adhesive layer 10. While ultraviolet light may be irradiated directly onto the pressure-sensitive adhesive layer 10, it is preferable to irradiate the pressure-sensitive adhesive layer 10 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 pressure-sensitive 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 pressure-sensitive 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 pressure-sensitive adhesive base material, the thickness of the pressure-sensitive adhesive layer, and the like. For ultraviolet light irradiation, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, or the like can be used.

[0110] Next, as shown in FIG. 1(c), after peeling and removing the support S2, a solution 12 of the additive 11 is applied to one side of the pressure-sensitive adhesive layer 10a (solution application step). The additive solution is not particularly limited as long as it is liquid and can be applied to and penetrate the pressure-sensitive 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 and a second crosslinking agent as a second trigger), 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 pressure-sensitive adhesive layer 10a.

[0111] The additive 11 in the solution 12 penetrates the surface of the pressure-sensitive adhesive layer 10a in the thickness direction into the pressure-sensitive adhesive layer 10a (solution penetration step). This state is shown in Figure 1(d). When the solution 12 is a solution in which the additive 11 is dissolved in the solvent 13, the solvent 13 penetrates into the surface of the pressure-sensitive adhesive layer 10a, causing it to swell, and the additive 11, dissolved in the solvent, penetrates into the pressure-sensitive adhesive layer 10a. The additive 11 becomes "dissolved" within the pressure-sensitive adhesive layer 10a.

[0112] Furthermore, as the additive 11 penetrates the pressure-sensitive adhesive layer 10a, a concentration gradient may be formed 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).

[0113] Thereafter, the adhesive layer 10a is dried to obtain the adhesive sheet 1 shown in FIG. 1(e) (drying step). If the solution 12 is a solution in which the additive 11 is dissolved in the solvent 13, the permeated solvent 13 evaporates in the drying step. 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. When 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.

[0114] The additives can be any additives used in the field of pressure-sensitive adhesives without any particular limitation, and examples thereof include polymerization initiators, crosslinking agents, ultraviolet 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 viewpoint of easily achieving the desired effects of the present invention, polymerization initiators, crosslinking agents, ultraviolet absorbers, rust inhibitors, and antistatic agents are preferred.

[0115] However, acids are not preferred as the additives, i.e., acids are excluded from the additives. Examples of such acids include organic acids such as acetic acid, propionic acid, and lactic acid, and particularly lactic acid.

[0116] Examples of the polymerization initiator and crosslinking agent include the same polymerization initiators and crosslinking agents that can be contained in the above-mentioned pressure-sensitive adhesive base material, and these can be used alone or in combination of two or more.

[0117] 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 a 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.

[0118] After the pressure-sensitive adhesive layer curing step, 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 may be used as additive 11. However, it is also possible to use both the second polymerization initiator and the second crosslinking agent as additives.

[0119] 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, 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 impossible with conventional hybrid pressure-sensitive adhesive sheets. 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.

[0120] The ultraviolet absorber is not particularly limited, but examples thereof include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, etc., and these can be used alone or in combination of two or more. Among these, triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and benzophenone-based ultraviolet absorbers are preferred, and at least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers having two or less hydroxyl groups per molecule, and benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers having one benzotriazole skeleton per molecule is preferred because it has good solubility and high ultraviolet absorption ability at a wavelength of around 380 nm.

[0121] Specific examples of triazine-based ultraviolet absorbers having two or less hydroxyl groups per 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-triazine]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), reaction products of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine with (2-ethylhexyl)-glycidic acid ester (TINUVIN 405, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]phenol (TINUVIN 1577, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol (ADK STAB LA46, manufactured by ADEKA), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN479, manufactured by BASF), and the like.

[0122] 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 7-9Branched and linear alkyl) ester compounds (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), methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 reaction product (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 (TINUVIN234, manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN326, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN328, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVI 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 (TINUVIN213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN571, manufactured by BASF), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (Sumisorb250, manufactured by Sumitomo Chemical Co., Ltd.).

[0123] Furthermore, examples of the benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and oxybenzophenone-based ultraviolet 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.

[0124] 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 (TINUVIN120, manufactured by BASF).

[0125] Examples of the cyanoacrylate ultraviolet absorber (cyanoacrylate compound) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

[0126] The maximum absorption wavelength in the absorption spectrum of the ultraviolet absorber is preferably in the wavelength range of 300 to 400 nm, 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 means the absorption maximum wavelength showing the greatest absorbance among them.

[0127] 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 by a single coating process, thereby improving production efficiency. Furthermore, when the 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.

[0128] The rust inhibitor is not particularly limited, but examples thereof include benzotriazole compounds, amine compounds, etc. Other examples include ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, dicyclohexylamine benzoate, urea, urotropine, thiourea, phenyl carbamate, cyclohexylammonium-N-cyclohexylcarbamate (CHC), etc. The rust inhibitors can be used alone or in combination of two or more.

[0129] Examples of the benzotriazole-based compound 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; triazole, 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, methylbenzotriazole cyclohexylamine salt, and the like.

[0130] Examples of the amine compound include hydroxy 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.

[0131] The antistatic agent is not particularly limited, but in terms of compatibility with acrylic polymers and transparency of the adhesive layer, an ionic compound containing a fluorine-containing anion is preferred. 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 can be used alone or in combination of two or more.

[0132] The solvent is not particularly limited as long as it can dissolve the additive and swell the adhesive layer 10a, but non-aqueous solvents are preferred because aqueous solvents have poor wettability to the adhesive layer and the additives do not easily penetrate. The non-aqueous solvent is not particularly limited, but examples thereof include 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. The solvents can be used alone or in combination of two or more.

[0133] The concentration of the additive in the solution can be appropriately set depending on the desired properties to be imparted to the pressure-sensitive adhesive layer 10a, and can be appropriately selected, for example, to 95% by weight or less (e.g., 0.1 to 95% by weight, 0.1 to 90% by weight, 0.1 to 85% by weight, 0.1 to 80% by weight, 0.1 to 70% by weight, 0.1 to 60% by weight, 0.1 to 50% by weight, 0.1 to 40% by weight, etc.), or to 0.1% by weight or more (e.g., 0.1 to 95% by weight, 0.2 to 95% by weight, 0.3 to 95% by weight, 0.4 to 95% by weight, 0.5 to 95% by weight, 1 to 95% by weight, 1.5 to 95% by weight, 3 to 95% by weight, 5 to 95% by weight, etc.). When the concentration of the additive in the solution is within this range, the additive is dissolved and the pressure-sensitive adhesive layer 10a is sufficiently swollen, thereby imparting the appropriate desired properties to the pressure-sensitive adhesive layer 10a.

[0134] 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 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 set appropriately 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 set appropriately 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, UV absorber, rust inhibitor, antistatic agent) is higher than the above range, the additives may bleed out or distribution may vary 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).

[0135] The solution 12 can be applied (coated) onto the adhesive layer 10a using a known coating method, 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.

[0136] 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 may be, for example, 1 to 1000 μg / cm 2, preferably 1 to 500 μg / cm 2 , more preferably 1 to 300 μg / cm 2 , and more preferably 1 to 100 μg / cm 2 If the amount of the additive solution to be applied falls within this range, the additive can be dissolved while providing the adhesive layer 10a with sufficient required properties.

[0137] After applying the additive solution to the pressure-sensitive adhesive layer 10a, the solution may be left to stand, if necessary, to allow the additive to penetrate. The standing time is not particularly limited and can be appropriately selected, for example, within 15 minutes, and can be selected, for example, from the range of 1 second to 10 minutes, preferably 5 seconds to 5 minutes. The standing temperature can be room temperature (approximately 10 to 30°C). When left standing under the above conditions, the additive can be sufficiently penetrated into the pressure-sensitive adhesive layer 10a.

[0138] The heating 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, 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.

[0139] FIG. 2(a) is a cross-sectional view showing one embodiment of the pressure-sensitive adhesive sheet according to the third aspect of the present invention, and FIG. 2(b) is a cross-sectional view showing another embodiment of the pressure-sensitive adhesive sheet according to the third aspect of the present invention.

[0140] 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 one first main surface 21a of the adhesive layer 21, but no support is attached to the other second main surface 21b of the adhesive layer 21.

[0141] 2(b), a pressure-sensitive adhesive sheet 2B according to one embodiment of the present invention is composed of an optically transparent pressure-sensitive adhesive layer 21, a first support S2 consisting of a release sheet attached to one first main surface 21a of the pressure-sensitive adhesive layer 21, and a second support S1 consisting of a release sheet attached to the other second main surface 21b of the pressure-sensitive adhesive layer 21. The pressure-sensitive adhesive sheet 2B can be obtained by attaching the support S2 to the first main surface 21a of the pressure-sensitive adhesive sheet 2A.

[0142] 2(a) and 2(b), the dotted line X-X' is a line that divides the pressure-sensitive adhesive layer 21 into two equal parts in the thickness direction. If the thickness of the pressure-sensitive 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.

[0143] In Fig. 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 forming step and adhesive layer curing step described above, and corresponds to adhesive layer 10a in Fig. 1. Therefore, adhesive layer 21 is preferably a cured adhesive layer.

[0144] A "single layer" of a pressure-sensitive adhesive layer means that it is not a laminated structure. For example, forming a pressure-sensitive adhesive layer made of a transparent pressure-sensitive adhesive base material, and then forming a pressure-sensitive adhesive layer made of the same transparent pressure-sensitive adhesive base material on top of that, is a laminated structure, not a single layer. Similarly, forming a pressure-sensitive adhesive layer made of a transparent pressure-sensitive adhesive base material with additives dissolved therein, and then forming a pressure-sensitive adhesive layer made of a transparent pressure-sensitive adhesive base material with additives dissolved therein at different concentrations on top of that, is a laminated structure, not a single layer.

[0145] The thickness of the pressure-sensitive adhesive layer 21 is not particularly limited, but is usually 5 μm to 500 μm, preferably 5 μm to 400 μm, and more preferably 5 μm to 350 μm. If the thickness of the pressure-sensitive adhesive layer 21 is within this range, it is suitable for forming a concentration gradient of the additive in the thickness direction of the pressure-sensitive adhesive layer 21.

[0146] 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.

[0147] The 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.

[0148] The additive 11 is formed by the penetration of the additive 11 into the pressure-sensitive adhesive layer 21 through the solution application step, solution penetration step, and drying step, and a concentration gradient of the additive 11 can be generated in the thickness direction of the pressure-sensitive adhesive layer 21 as shown in Fig. 2. Therefore, when the single-layer pressure-sensitive adhesive layer 21 is divided into two equal parts in the thickness direction, the concentration of the additive in the region to which the first main surface 21a, one of the two main surfaces, belongs will be different from the concentration of the additive in the region to which the other second main surface 21b belongs. The case where there is no additive in the region with the lower additive concentration (the additive concentration is 0) is also included in the scope of the present invention.

[0149] 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 are taken to mean the average concentration of the additive in each region when there is a concentration gradient within each region.

[0150] 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, and 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.

[0151] In the pressure-sensitive adhesive sheet according to the third aspect of the present invention, additives such as anti-rust agents and anti-static agents are distributed in high concentrations near first main surface 21a, as shown in Fig. 2, thereby imparting the desired properties of the additives, such as anti-rust function and anti-static function, to first main surface 21a. Meanwhile, the concentration of additive 11 throughout pressure-sensitive adhesive layer 21 can be reduced, thereby reducing changes in the physical properties of pressure-sensitive adhesive layer 21 caused by additive 11.

[0152] The pressure-sensitive adhesive sheet according to the third aspect of the present invention can be used to bond a transparent optical member to another optical member in an image display device such as a liquid crystal image display device or an organic electroluminescence (EL) image display device. Examples of the optical member include a polarizing film, a retardation film, a transparent cover member such as a cover glass, and various other transparent optical members. The optical member of the present invention also includes a glass substrate on which a transparent conductive layer such as a patterned ITO film is formed. The pressure-sensitive adhesive sheet according to 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 member.

[0153] FIG. 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 FIG. 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 FIG. 2(b) and bonding the first and second optical components. The transparent first optical component 31 and second optical component 32 can be formed from a polarizing film, a retardation film, or other optical film used in optical display devices, or a transparent cover member such as a cover glass on the viewing side of an optical display device. The first optical component 31 is bonded to the first main surface 21a of the pressure-sensitive adhesive layer 21, and the second optical component 32 is bonded to the second main surface 21b of the pressure-sensitive adhesive layer 21.

[0154] 4A and 4B are diagrams schematically illustrating steps for carrying out one embodiment of the method for producing an optical member laminate according to the second aspect of the present invention. In this embodiment, as shown in FIG. 4A, a substrate 42 (hereinafter sometimes simply referred to as "substrate 42") made of an adhesive sheet 2C and an optical member is used.

[0155] 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.

[0156] 4(a), in this embodiment, the pressure-sensitive adhesive layer 41 is cured by the reaction of the first polymerization initiator and the first crosslinking agent (not shown), and the second polymerization initiator 11a and the second crosslinking agent 11b are dispersed in a dissolved state. The present invention also encompasses an embodiment in which only one of the second polymerization initiator 11a and the second crosslinking agent 11b is dissolved in the pressure-sensitive adhesive layer 41.

[0157] In this embodiment, adhesive sheet 2C has support S3, but support S3 is not necessary. In this embodiment, a concentration gradient of second polymerization initiator 11a and second cross-linking agent 11b exists in the thickness direction from main surface 41a where pressure-sensitive adhesive layer 41 contacts support S3.

[0158] In this embodiment, the main surface 42a of the substrate 42 in Fig. 4(a) to be 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 a transparent cover member. The present invention also encompasses the use of a substrate 42 without a printed layer 43.

[0159] 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 a known method, such as heating and pressurizing using an autoclave. 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. This provides high fluidity and excellent level difference absorption. Therefore, the adhesive layer 41 is bonded to the main surface 42a of the substrate 42 so as to completely fill the level difference between the printed layer 43 and the printed layer 43.

[0160] Next, the pressure-sensitive adhesive layer 41 is cured by a reaction of at least one selected from the group consisting of a second polymerization initiator 11a and a second cross-linking agent 11b (a second trigger). The method for curing the pressure-sensitive adhesive layer 41 is not particularly limited as long as the curing reaction proceeds due to the second trigger, but examples thereof include heating the pressure-sensitive adhesive layer 41 and irradiating the pressure-sensitive adhesive layer 41 with active energy rays to cure the layer. If necessary, the pressure-sensitive adhesive layer 41 may be further heated and dried. Examples of active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred.

[0161] The conditions for curing the pressure-sensitive adhesive layer 41 may be appropriately set, for example, the heating temperature, time, or the amount of active energy ray irradiation so that the pressure-sensitive adhesive layer 41 exhibits a high elastic modulus and excellent adhesive reliability.

[0162] FIG. 4(c) shows an embodiment in which the adhesive layer 41 is irradiated with ultraviolet light U to cure the adhesive layer 41. The irradiation of ultraviolet light U decomposes the second polymerization initiator 11a to generate radicals or ions, which initiate the polymerization and cross-linking reaction of the second cross-linking agent 11b. The adhesive layer 41 may be irradiated with ultraviolet light directly or via a support S3. FIG. 4(c) shows an embodiment in which the adhesive layer 41 is irradiated with ultraviolet light U via a 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 the ultraviolet light U is irradiated.

[0163] By curing the pressure-sensitive adhesive layer 41, an optical component laminate 4 is obtained as shown in Fig. 4(d). In Fig. 4(d), 41c is the pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive layer 41. The optical component laminate 4 is an embodiment showing one example of the optical component laminate according to the fourth aspect of the present invention.

[0164] By curing the adhesive layer 41, the crosslinking agent 11b crosslinks and polymerizes to form a crosslinked structure 11c, thereby forming an adhesive layer 41c. The adhesive layer 41c has an improved elastic modulus and improved adhesive reliability to the substrate 42. Therefore, the adhesive layer 41c suppresses the generation of gases such as carbon dioxide due to heating of the substrate 42 (plastic film), preventing the generation of bubbles.

[0165] 4(d), the pressure-sensitive adhesive layer 41c has a higher crosslink density 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 member 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, tensile stress is generally applied to the outside and compressive stress is applied to the inside, with the stress on the outside being stronger than the stress on the inside. Therefore, by positioning the main surface 41a of the adhesive layer 41c on the outside when bending the flexible display, durability against bending can be improved.

[0166] 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 adhesive layer 41c is a single layer having two opposing main surfaces and made of a transparent adhesive base material cured by a reaction between the first polymerization initiator and a first crosslinking agent (first trigger) and a reaction between at least one agent (second trigger) selected from the group consisting of the second polymerization initiator 11a and a second crosslinking agent 11b; When the single layer of 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 principal surface 41a, one of the two principal surfaces, belongs is different from the density of the cross-linked structure 11c in the region to which the second principal surface 41b, the other principal surface, belongs.

[0167] In this embodiment, the adhesive layer 41c is laminated so as to fill in the step between the main surface 42a of the substrate 42 and the print layer 43. [Example]

[0168] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0169] (Preparation of 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 mixed with 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 184", manufactured by BASF) and 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 651", manufactured by BASF), 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, yielding a prepolymer composition in which some of the monomer components had polymerized.

[0170] 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 of the pressure-sensitive adhesive layer after formation 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, an illuminance of 5 mW / cm was applied. 2 , Light amount: 1500mJ / cm 2 The pressure-sensitive adhesive composition layer was photocured under the conditions of UV irradiation, to form a pressure-sensitive adhesive sheet A.

[0171] (Preparation of adhesive sheet B) An adhesive sheet B was formed in the same manner as adhesive sheet A, except that the amount of hexanediol diacrylate (HDDA) added was 0.1 parts by weight.

[0172] (Preparation of adhesive sheet C) Adhesive sheet C was formed in the same manner as 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 adhesive layer after formation was 23 μm.

[0173] (Preparation of adhesive sheet D) Adhesive sheet D was formed in the same manner as 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 adhesive layer formation was 150 μm.

[0174] (Preparation of adhesive sheet E) Adhesive sheet E was formed in the same manner as adhesive sheet A, except that the monomer mixture used was 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).

[0175] (Preparation of adhesive sheet F) Adhesive sheet F was formed in the same manner as adhesive sheet A, except that the monomer mixture used was 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), and 0.02 parts by weight of trimethylolpropane triacrylate (TMPTA) was used instead of hexanediol diacrylate (HDDA).

[0176] (Preparation of adhesive sheet G) Adhesive sheet G was formed in the same manner as 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 adhesive layer formation was 250 μm.

[0177] Example 1 The release film on one main surface (referred to as the "first side") 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 side using a wire wound rod type No. 7 bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After coating, PSA sheet A was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, yielding PSA sheet A comprising a PSA layer in which the ultraviolet absorber was dissolved.

[0178] (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.

[0179] Example 2 An adhesive sheet B including an adhesive layer in which an 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% by weight was applied to the adhesive sheet B.

[0180] 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 with a concentration of 12% by weight in methyl ethyl ketone was applied to the adhesive sheet B.

[0181] Example 4 Adhesive sheet B was obtained in the same manner as in Example 1, except that an ethyl acetate solution of an ultraviolet absorber (Seesorb 106, manufactured by Shipro Chemical Co., Ltd.) with a concentration of 15% by weight was applied to adhesive sheet B, and the adhesive sheet B included an adhesive layer in which the ultraviolet absorber was dissolved.

[0182] (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.

[0183] 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.

[0184] Example 6 An adhesive sheet C including an adhesive layer in which an 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% by weight was applied to the adhesive sheet C.

[0185] 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 to the adhesive sheet C.

[0186] Example 8 An adhesive sheet C including an adhesive layer in which an ultraviolet absorber (Seesorb 106, manufactured by Shipro Chemical 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% by weight was applied to the adhesive sheet C.

[0187] (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.

[0188] 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 pressure-sensitive adhesive sheet C was used and ethyl acetate containing no ultraviolet absorber was applied.

[0189] 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.

[0190] (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.

[0191] 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.

[0192] (Comparative Example 6) The release film on the first surface of the pressure-sensitive adhesive sheet F was peeled off, and the pressure-sensitive adhesive sheet E to which the ultraviolet absorber solution was not applied was used as Comparative Example 6.

[0193] 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.

[0194] (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.

[0195] (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.

[0196] (Comparative Example 9) A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the UV absorber was uniformly dissolved was obtained in the same manner as 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 UV absorber (Tinosorb S, manufactured by BASF) was further blended into the acrylic pressure-sensitive adhesive composition.

[0197] <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 transmittance (%) at 380 nm and 420 nm is shown in Table 1.

[0198] <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, with a PET film (thickness: 25 μm) laminated to the other side. The laminate was then laminated using a hand roller and heated and pressurized in an autoclave (5 atm, 50°C) for 15 minutes. The adhesive strength (N / 10 mm) of the resulting samples was measured using an autograph (pull rate: 60 mm / min, peel angle: 180°). Three samples were prepared for each condition, and the number average was taken. The adhesive strength (N / 10 mm) of the first and second sides to alkali glass, as well as the difference between them, are shown in Table 1.

[0199] [Table 1]

[0200] Table 1 shows that applying a solution of ultraviolet absorber to the adhesive layer of an adhesive sheet cured by ultraviolet light can impart excellent ultraviolet absorption properties to the adhesive layer. In addition, the difference in adhesive strength between the first and second sides of the adhesive layer is 1.0 N / mm, which shows that applying a solution of ultraviolet absorber to the adhesive layer of a cured adhesive sheet can minimize the difference in physical properties such as adhesive strength between the front and back of the adhesive layer.

[0201] <Evaluation of UV absorber distribution in the thickness direction of 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, C 30 +H 32 +N3+O5).

[0202] Analytical equipment: TOF-SIMS (ULVAC-PHI, TRIFT V) Etching ions: Ar gas cluster ions Irradiated primary ions: Bi3 2+ Accelerating voltage: 30 kV Measurement polarity: negative ions

[0203] Figure 5(a) shows that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of Example 9 has a concentration gradient of the ultraviolet absorber (Tinosorb S) from the first surface to the second surface, while Figure 5(b) shows that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of Comparative Example 9 has the ultraviolet absorber (Tinosorb S) distributed at a constant concentration from the first surface to the second surface.

[0204] Example 12 The release film on one main surface (referred to as "side 1") of PSA 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 BV) diluted to a concentration of 1 wt% was applied to the exposed side using a wire wound rod type #7 bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After application, PSA sheet A was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, yielding PSA sheet A containing a PSA layer in which HDDA had been dissolved.

[0205] 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.

[0206] 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 BV) was applied to the adhesive sheet G.

[0207] 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 to a concentration of 2 wt % hexanediol diacrylate (HDDA) and 0.1 wt % photopolymerization initiator (Omnirad 184, manufactured by IGM Resins BV) was applied to the adhesive sheet G.

[0208] 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 BV) was applied to the adhesive sheet G.

[0209] 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 % trimethylolpropane triacrylate (TMPTA) and 0.25 wt % photopolymerization initiator Omnirad 184 (manufactured by IGM Resins BV) was applied to the adhesive sheet G.

[0210] <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: 1Hz Heating rate: 5°C / min Shape: Parallel plate 7.9mmφ

[0211] Next, the measurement sample is placed under an illumination intensity of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2The composition was cured by irradiating ultraviolet light under the conditions shown above, and the dynamic viscoelasticity was measured using the method described above. Table 2 shows the storage modulus at 85°C before and after curing.

[0212] [Table 2]

[0213] In Examples 12 to 17, the storage modulus was improved by applying a crosslinker solution to the pressure-sensitive adhesive layer and subjecting the dried pressure-sensitive adhesive sheets A, B, and G to curing conditions. Therefore, it is clear that the pressure-sensitive adhesive sheets of Examples 12 to 17 are useful as hybrid pressure-sensitive adhesive sheets. Furthermore, Examples 15 and 16 also show that the storage modulus after curing can be controlled by adjusting the concentration of the crosslinker solution.

[0214] 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.

[0215] (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.

[0216] <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 pressure-sensitive adhesive sheets obtained 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 (product 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: 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 copper surface resistance was measured using a Hall hardness measurement device (Accent Optical Technologies HL5500PC). The copper surface was also visually observed to evaluate the presence or absence of corrosion. After storage, the presence or absence of the rust inhibitor was also confirmed using a microscope. The results are shown in Table 3.

[0217] [Table 3]

[0218] Table 3 shows that applying a rust inhibitor solution to the adhesive layer can impart rust prevention properties to the adhesive. In addition, the surface resistance value of the first side, to which the rust inhibitor solution was applied, was lower after 500 hours than that of the second side, suggesting that there is a difference in the concentration of the rust inhibitor between the front and back sides.

[0219] Example 19 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 5 wt% ethanol solution of an antistatic agent (lithium bis(trifluoromethanesulfonyl)imide) 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 antistatic agent was dissolved.

[0220] Example 20 An adhesive sheet C including an 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 %.

[0221] Example 20 An adhesive sheet C including an 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 %.

[0222] (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.

[0223] <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

[0224] [Table 4]

[0225] Table 4 shows that applying an antistatic agent solution to the adhesive layer can impart antistatic properties to the adhesive.

[0226] Example 22 The release film on one main surface (referred to as "side 1") of PSA sheet B was peeled off, and an ethyl acetate solution containing 10 wt% UV absorber (Tinosorb S, manufactured by BASF), 20 wt% hexanediol diacrylate (HDDA), and 0.3 wt% photopolymerization initiator (Omnirad 819, manufactured by IGM Resins BV) diluted to a concentration of 10 wt% was applied to the exposed side using a wire wound rod type #7 bar coater manufactured by RD Specialties (target wet coating thickness: 15 μm). After application, PSA sheet B was heated and dried in an oven at 110°C for 2 minutes to volatilize and remove the solvent, yielding PSA sheet B comprising a PSA layer containing the UV absorber and HDDA dissolved therein.

[0227] Example 23 An adhesive sheet B containing an adhesive layer in which the ultraviolet absorber (Tinuvin 928, manufactured by BASF) was dissolved and the HDDA was dissolved 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 BV) was applied.

[0228] 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 BV) was applied.

[0229] 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 BV) was applied.

[0230] <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.

[0231] [Table 5]

[0232] It can be seen that the pressure-sensitive adhesive sheets of Examples 22 and 23, which were coated with a solution containing an UV absorber in addition to a photopolymerization initiator and a crosslinking agent, had a higher storage modulus after curing and improved adhesive reliability compared to the pressure-sensitive 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, having absorbed UV light, generated heat, accelerating the curing reaction.

[0233] 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; Drying the adhesive layer 1. A method for producing a pressure-sensitive adhesive sheet, comprising the steps of: [Appendix 2] The solution of the additive is a solution in which the additive is dissolved in a solvent, Attachment 1, a method for producing a pressure-sensitive adhesive sheet, comprising a step of drying the pressure-sensitive adhesive layer to evaporate the solvent of the solution. [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 of adhesive layer is divided into two equal parts in the thickness direction, An adhesive sheet characterized in that the concentration of the additive in the region to which the first main surface, one of the two main surfaces, belongs is different from the concentration of the additive in the region to which the other second main surface 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 is made of 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, 22. 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 any one of claims 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 according to claim 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 member laminate according to appendix 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. [Industrial Applicability]

[0234] INDUSTRIAL APPLICABILITY 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 member to another optical member, and for a pressure-sensitive adhesive sheet obtainable by the production method. [Explanation of symbols]

[0235] 10 Adhesive layer (before curing) 10a Adhesive layer (after curing) S, S1, S2, S3 Support (Release sheet) U: Ultraviolet light 11 Additives 11a Second polymerization initiator 11b Second Crosslinker 11c Crosslinked structure 12 Additive solution 13 Solvents 31, 32 Optical components 21 Adhesive layer (after curing) 21a Main surface (first surface) of adhesive layer 21b Main surface (second surface) of adhesive layer 41 Adhesive layer (before curing) 41a Main surface (first surface) of adhesive layer 41b Main surface (second surface) of adhesive layer 42 Optical Components 42a Main surface of optical member 43 Printing layer

Claims

1. 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; Drying the adhesive layer 1. A method for producing a pressure-sensitive adhesive sheet, comprising the steps of:

2. A method for manufacturing an adhesive sheet as described in claim 1, comprising a step of evaporating the solvent of the solution by drying the adhesive layer.

3. The method for producing a pressure-sensitive adhesive sheet according to claim 1 or 2, further comprising the step of attaching a release sheet to the surface of the pressure-sensitive adhesive layer opposite to the support.

4. 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.

5. 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.

6. The method for producing a pressure-sensitive adhesive sheet according to claim 5 , wherein the additive further comprises an ultraviolet absorber.

7. 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.

8. The method for producing a pressure-sensitive adhesive sheet according to claim 7 , wherein the first polymerization initiator is the same as the second polymerization initiator.

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 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.

10. 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.

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; 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 of pressure-sensitive adhesive layer is divided into two equal parts in the thickness direction, An adhesive sheet characterized in that 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.

12. 12. The pressure-sensitive adhesive sheet according to claim 11, wherein 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.

13. The pressure-sensitive adhesive sheet according to claim 11 or 12, wherein the single-layer pressure-sensitive adhesive layer has a concentration gradient of the additive in the thickness direction.

14. The pressure-sensitive adhesive sheet according to any one of claims 11 to 13, wherein the support is a release sheet.

15. 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.

16. 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 antistatic agent.

17. 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.

18. The pressure-sensitive adhesive sheet according to claim 17 , wherein the additive further comprises an ultraviolet absorber.

19. 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. 20. The pressure-sensitive adhesive sheet according to claim 19, wherein the first polymerization initiator is the same as the second polymerization initiator.

21. 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.

22. 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.

23. 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. 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.

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