TWI777753B - Manufacturing method of display body - Google Patents

Abstract

The subject of the present invention is to provide an adhesive sheet having high film strength of the adhesive layer and excellent in both step followability and blister resistance, a display body excellent in both step followability and blister resistance, and the and other manufacturing methods. The solution of the present invention is to provide an adhesive sheet 1, which is an adhesive sheet 1 provided with an adhesive layer 11 for attaching a display body constituent member 21 to another display body constituent member 22. The adhesive layer 11 series has a crosslinked structure composed of a (meth)acrylate copolymer (A) and a thermal crosslinking agent (B), and is composed of an ultraviolet curable component (C) and acetonitrile at a concentration of 0.1% by mass. The solution is composed of a photopolymerization initiator (D) with an absorbance of 0.3 or more at a wavelength of 380 nm and an ultraviolet curable adhesive.

Description

Manufacturing method of display body

The present invention relates to an adhesive sheet for laminating display body constituent members, a display body formed by laminating display body constituent members, and a manufacturing method of these articles.

In recent years, various portable electronic devices such as mobile phones, smart phones, and tablet terminal devices have used displays including liquid crystal elements, light emitting diodes (LED elements), organic electroluminescence (organic EL) elements, and the like. The display body (display) of the body module.

In such a display, a protective panel is usually provided on the surface side of the display module. Between the protection panel and the display module, a gap is provided in such a way that even if the protection panel is deformed by an external force, the deformed protection panel will not collide with the display module.

However, when there is a gap as described above, that is, the air layer, the reflection loss of light caused by the difference in refractive index between the protective panel and the air layer and the refractive index difference between the air layer and the display module is relatively large, and there are displays The problem of low picture quality.

Therefore, there are proposals to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, on the display module side of the protective panel, the frame-shaped printed layer exists as a level difference. When the adhesive layer does not follow the step, the adhesive layer floats in the vicinity of the step, thereby causing a reflection loss of light. Therefore, the above-mentioned adhesive layer system is required to be step-following.

In order to solve the above-mentioned problems, Patent Document 1 discloses an ultraviolet crosslinkable adhesive sheet comprising a (meth)acrylic copolymer containing a monomer, wherein the monomer contains a portion having ultraviolet crosslinkability (two (meth)acrylate of phenyl ketone structure), and the storage elastic modulus before and after UV crosslinking is specified. In this type of ultraviolet crosslinkable adhesive sheet, after the adherend is attached, it is irradiated with ultraviolet rays to advance the crosslinking reaction and improve the cohesion. The ultraviolet cross-linkable adhesive sheet has a low storage elastic modulus at the stage of adhering to the adherend, that is, the stage before ultraviolet cross-linking, so it is easy to follow the step difference of the adherend. prior art literature Patent Literature

[Patent Document 1] Japanese Patent Laid-Open No. 2011-184582

The problem to be solved by the invention

However, the (meth)acrylic copolymer used in the ultraviolet crosslinkable adhesive sheet of Patent Document 1 has low crosslinking density and cohesive force before ultraviolet crosslinking, so this ultraviolet crosslinkable adhesive sheet The (meth)acrylic copolymer adheres to the blade during cutting, etc., or when the ultraviolet crosslinkable adhesive sheet is stored, etc., the (meth)acrylic copolymer oozes out from the ultraviolet crosslinkable adhesive sheet. situation. In this way, the film strength of the ultraviolet cross-linkable adhesive sheet in the patent document is low.

On the other hand, when an ultraviolet-curable adhesive containing a usual photopolymerization initiator is used for the above-mentioned ultraviolet cross-linkable adhesive sheet, the ultraviolet-curable adhesive may not be sufficiently cured depending on the type of the protective panel. Problems arise in durable conditions. For example, when high temperature and high humidity conditions are applied, air bubbles are generated in the vicinity of the level difference, or exhaust gas is generated from the plastic plate of the protective panel, and foaming such as air bubbles, floating, and peeling occurs.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an adhesive sheet having a high film strength of an adhesive layer and excellent in both step followability and blister resistance. Excellent displays of both parties, and methods of manufacturing such items. means of solving problems

In order to achieve the above object, a first aspect of the present invention provides an adhesive sheet, which is an adhesive sheet provided with an adhesive layer for laminating a display component member and another display component member, characterized in that the above-mentioned adhesive The agent layer has a cross-linked structure composed of a (meth)acrylate copolymer (A) and a thermal cross-linking agent (B), and is composed of an ultraviolet curable component (C) and a concentration of 0.1 mass %. The photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm of an acetonitrile solution of 0.3 or more is composed of an ultraviolet curable adhesive (Invention 1).

In the adhesive sheet of the above invention (Invention 1), since the adhesive constituting the adhesive layer is thermally cross-linked, the film strength of the adhesive layer is high. In addition, since the adhesive layer contains a specific photopolymerization initiator (D), even when a display component and/or other display components contain an ultraviolet absorber, the adhesive layer can be absorbed by ultraviolet light. It is sufficiently hardened by irradiation and has excellent step followability and blister resistance.

In the above invention (Invention 1), the gel fraction of the adhesive is preferably 30% or more and 70% or less (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that at least one of the above-mentioned one display body constituent member and the above-mentioned other display body constituent members contains an ultraviolet absorber (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferable that at least the surface on the side to be bonded has a level difference (Invention 4).

In the above inventions (Inventions 1 to 4), the adhesive sheet is preferably provided with two release sheets, and the adhesive layer is preferably held between the release sheets so as to contact the release surfaces of the two release sheets (Invention 5). ).

The second aspect of the present invention provides a method for manufacturing an adhesive sheet, which is a method for manufacturing an adhesive sheet including an adhesive layer for laminating one display component member and another display component member, characterized in that: By photopolymerization containing a (meth)acrylate copolymer (A), a thermal crosslinking agent (B), an ultraviolet curable component (C), and an acetonitrile solution with a concentration of 0.1 mass % having an absorbance of 0.3 or more at a wavelength of 380 nm The adhesive composition of the initiator (D) is coated and thermally cross-linked to form a UV-curable adhesive layer (Invention 6).

The third aspect of the present invention is to provide a display including a display constituent member, another display constituent member, and a cured adhesive layer that adheres the one display constituent member and the other display constituent member to each other. A display body, characterized in that the cured adhesive layer has a cross-linked structure composed of a (meth)acrylate copolymer (A) and a thermal cross-linking agent (B), and also contains an ultraviolet curable component. (C) and the adhesive of the photopolymerization initiator (D) whose absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass is 0.3 or more (Invention 7).

A fourth aspect of the present invention provides a display including a display constituent member, another display constituent member, and a cured adhesive layer for bonding the one display constituent member and the other display constituent member to each other. A display body, characterized in that the cured adhesive layer has a cross-linked structure composed of a (meth)acrylate copolymer (A) and a thermal cross-linking agent (B), and also contains an ultraviolet curable component. (C) consists of the adhesive agent, and the gel fraction of the said adhesive agent layer after hardening is 40% or more and 95% or less (Invention 8).

A fifth aspect of the present invention provides a method for manufacturing a display, characterized in that a display component is produced by laminating one display component and another display component through the adhesive layer of the above-mentioned adhesive sheet (Inventions 1 to 5). In the laminated body, ultraviolet rays are irradiated to the adhesive layer of the laminated body, so that the adhesive layer becomes an adhesive layer after curing (Invention 9). Invention effect

The adhesive layer of the adhesive sheet of the present invention has high film strength, and is excellent in both step followability and foam resistance. In addition, the display body of the present invention is excellent in both step followability and foam resistance. Furthermore, according to the method of the present invention, the adhesive sheets and the display body can be manufactured.

Form for carrying out the invention

Hereinafter, embodiments of the present invention will be described. (adhesive board) The adhesive sheet of the present embodiment is an adhesive sheet provided with an adhesive layer for bonding one display body constituent member and another display body constituent member. The display body and the display body constituent members will be described later.

As shown in FIG. 1, as an example, the adhesive sheet 1 of the present embodiment is composed of the following: two release sheets 12a, 12b; The adhesive layer 11 sandwiched by the two release sheets 12a, 12b. In addition, the peeling surface of a peeling sheet in this specification means the surface which has peeling property of a peeling sheet, and includes any of the surface which performed peeling process, and the surface which shows peeling property without performing peeling process.

1. Adhesive layer The above-mentioned adhesive layer 11 has a cross-linked structure composed of a (meth)acrylate copolymer (A) and a thermal cross-linking agent (B), and contains an ultraviolet curable component (C) and a concentration of A 0.1 mass % acetonitrile solution has an absorbance at a wavelength of 380 nm of 0.3 or more and is composed of an ultraviolet curable adhesive of the photopolymerization initiator (D). In other words, the above-mentioned adhesive layer 11 is composed of a wavelength containing a (meth)acrylate copolymer (A), a thermal crosslinking agent (B), an ultraviolet curable component (C), and an acetonitrile solution at a concentration of 0.1% by mass. The photopolymerization initiator (D) having an absorbance at 380 nm of 0.3 or more is composed of an ultraviolet curable adhesive formed by thermal crosslinking of the adhesive composition (hereinafter referred to as "adhesive composition P"). In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

As mentioned above, the adhesive layer 11 of the adhesive sheet 1 is composed of an adhesive obtained by thermally crosslinking the adhesive composition P, and the adhesive is composed of a (meth)acrylate copolymer (A) and the cross-linked structure formed by the thermal cross-linking agent (B). On the other hand, the ultraviolet curable component (C) is not yet cured, and is present in the adhesive in the state after being blended in the adhesive composition P. This ultraviolet curable component (C) polymerizes and hardens when the adhesive layer 11 is irradiated with ultraviolet rays during use of the adhesive sheet 1 (after bonding to the adherend).

In the adhesive sheet 1 of the present embodiment, the adhesive constituting the adhesive layer 11 is thermally cross-linked, and has a certain degree of cross-linking density and predetermined cohesive force, so the adhesive layer 11 has a high film strength. Therefore, for example, at the time of cutting the adhesive sheet, etc., it is possible to suppress the occurrence of problems such as adhesion of the adhesive to the blade. Moreover, it is also possible to suppress the bleeding of the adhesive from the adhesive layer 11 at the time of storage of the adhesive sheet 1 or the like.

In addition, since the adhesive layer 11 of the adhesive sheet 1 of the present embodiment is relatively soft in the stage before curing by ultraviolet irradiation, when the adhesive sheet 1 is attached to the display component member having the step difference, The adhesive layer 11 easily follows the level difference, and can suppress generation of gaps, floating, and the like in the vicinity of the level difference.

On the other hand, when the adhesive sheet 1 of the present embodiment is used, after a display element constituting member is bonded to other display element constituting members through the adhesive layer 11 of the adhesive sheet 1, a display element constituting member or As for the other display constituent members, the adhesive layer 11 is irradiated with ultraviolet rays to cure the adhesive layer 11 to form a post-curing adhesive layer (in the second figure described later, the post-curing adhesive layer 11 ′). Thereby, even when the obtained laminated body (display body) is left to stand for 72 hours under high temperature and high humidity conditions, for example, 85° C., 85% RH conditions, generation of bubbles, floating, peeling, etc. in the vicinity of the level difference can be suppressed. Furthermore, it is possible to suppress the occurrence of foaming, such as air bubbles, floating, and peeling, at the interface between the display body constituent member and the cured adhesive layer. That is, the adhesive sheet 1 of the present embodiment is excellent in initial step followability, step followability under high temperature and high humidity conditions, and foaming resistance.

Here, when the above-mentioned one display component and/or other display component contains an ultraviolet absorber, when a previous photopolymerization initiator such as 1-hydroxycyclohexyl phenyl ketone is used as an adhesive, the When the adhesive layer is irradiated with ultraviolet rays by the above-mentioned one display element constituting member or other display element constituting members, the ultraviolet rays of the wavelengths used to crack the above-mentioned photopolymerization initiator are absorbed by the ultraviolet absorber in the display element constituting member, so that light is emitted. Cracking of the polymerization initiator is hindered. As a result, the curing reaction of the ultraviolet curable component does not proceed favorably, and the curing of the adhesive layer becomes insufficient. Therefore, the adhesive layer is inferior in step followability and foaming resistance under high temperature and high humidity conditions. On the other hand, the adhesive layer 11 of the adhesive sheet 1 of the present embodiment contains a photopolymerization initiator (D) having an absorbance of 0.3 or more at a wavelength of 380 nm in an acetonitrile solution with a concentration of 0.1 mass %. At this time, even if the adhesive layer 11 is irradiated with ultraviolet rays through the display element constituting member containing the ultraviolet absorber, the ultraviolet rays of the wavelength (long wavelength) for cracking the photopolymerization initiator (D) are not constituted by the display element. Since the ultraviolet absorber in the member absorbs, the photopolymerization initiator (D) is cracked without any problem. As a result, the curing reaction of the ultraviolet curable component (C) proceeds favorably, and the adhesive layer 11 is sufficiently cured. Thereby, the obtained layered body (display body) has excellent step followability and foaming resistance under high temperature and high humidity conditions. That is, when the adhesive sheet 1 of the present embodiment is used, even when one display component and/or other display component contains an ultraviolet absorber, it has excellent step followability and lift resistance under high temperature and high humidity conditions. Foamy.

(1) (Meth)acrylate copolymer (A) The (meth)acrylate copolymer (A) is a monomer unit constituting the polymer, and a reactive group-containing monomer having a reactive group reactive with the thermal crosslinking agent (B) in the molecule is used as good. The reactive group derived from the reactive group-containing monomer can react with the thermal crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure) to form the adhesive layer 11 with high film strength.

Examples of the reactive group-containing monomer include monomers having a hydroxyl group in the molecule (hydroxyl-containing monomer), monomers having a carboxyl group in the molecule (carboxyl group-containing monomer), and amines having an amine in the molecule. group-based monomers (amine group-containing monomers) and the like are preferred. Among these, hydroxyl-containing monomers which are excellent in reactivity with the thermal crosslinking agent (B) and have less adverse effects on the adherend are particularly preferred. Moreover, even if the weight average molecular weight of the (meth)acrylate copolymer (A) is low, it is preferable to use a carboxyl group-containing monomer from the viewpoint of exhibiting the required cohesive force.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. -Hydroxyalkyl (meth)acrylate such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. Especially in terms of reactivity with the thermal crosslinking agent (B) in the hydroxyl group of the obtained (meth)acrylate copolymer (A) and copolymerizability with other monomers, (methyl) 2-hydroxyethyl acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl (meth)acrylate is particularly preferred. These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. In particular, acrylic acid is preferable in terms of reactivity with the thermal crosslinking agent (B) in the carboxyl group of the obtained (meth)acrylate copolymer (A) and copolymerizability with other monomers. These may be used alone or in combination of two or more.

As an amino group-containing monomer, aminoethyl (meth)acrylate, n-butyl (meth)acrylate aminoethyl, etc. are mentioned, for example. These may be used alone or in combination of two or more.

The lower limit of the (meth)acrylate copolymer (A) as a monomer unit constituting the polymer and a hydroxyl group-containing monomer is preferably 3% by mass or more, particularly 10% by mass or more Preferably, it is more preferable to contain 15 mass % or more. In addition, the upper limit of the (meth)acrylate copolymer (A) is preferably 35% by mass or less of a hydroxyl group-containing monomer as the monomer unit of the polymer, and 30% by mass or less is preferably contained as the monomer unit of the polymer. It is especially preferable, and it is more preferable to contain 25 mass % or less. When the (meth)acrylate copolymer (A) contains the hydroxyl group-containing monomer in the above amount as a monomer unit, the obtained adhesive can form a favorable cross-linked structure and obtain an adhesive with high film strength While layering 11, a predetermined amount of hydroxyl groups remains in the adhesive. The hydroxyl group is a hydrophilic group. When the hydrophilic group exists in the adhesive in a predetermined amount, even if the adhesive is placed under high temperature and high humidity conditions, the compatibility with the water entering the adhesive is good under the high temperature and high humidity conditions. As a result, when returning to normal temperature and normal humidity, whitening of the adhesive can be suppressed (it has excellent wet-heat whitening resistance).

When the (meth)acrylate copolymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the (meth)acrylate copolymer (A) is a lower limit value containing 5 The carboxyl group-containing monomer is preferably contained in an amount of at least 7% by mass, preferably at least 7% by mass, and more preferably at least 10% by mass. In addition, the upper limit of the (meth)acrylate copolymer (A) is preferably 30 mass % or less of a carboxyl group-containing monomer as a monomer unit constituting the polymer, and 20 mass % or less is preferably contained More preferably, it is more preferable to contain 15 mass % or less. When the (meth)acrylate copolymer (A) contains a carboxyl group-containing monomer in the above amount as a monomer unit, the obtained adhesive can form a favorable cross-linked structure and obtain an adhesive layer 11 with high film strength. .

Moreover, it is also preferable that the (meth)acrylate copolymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, by not containing a carboxyl group-containing monomer, it is possible to suppress defects caused by acid on the adhesive attachment object, such as transparent conductive films such as indium tin oxide (ITO), metal films, etc. In some cases, such defects (corrosion, change in resistance value, etc.) due to acid can also be suppressed. However, a predetermined amount of the carboxyl group-containing monomer can be tolerated to such an extent that such a defect does not occur. Specifically, in the (meth)acrylate copolymer (A), the monomer unit can tolerate less than 5 mass % of the carboxyl group-containing monomer, preferably 2 mass % or less, particularly preferably 0.1 mass % or less.

The (meth)acrylate copolymer (A) can exhibit better adhesion by using alkyl (meth)acrylate having an alkyl group of 1 to 20 carbon atoms as a monomer unit constituting the polymer. Examples of alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylate. ) n-butyl acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-(meth)acrylate Decyl ester, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate and the like. In particular, from the viewpoint of improving adhesiveness, (meth)acrylates having 1 to 8 carbon atoms in the alkyl group are preferred, and n-butyl (meth)acrylates or 2-(meth)acrylates are preferred. Ethylhexyl ester is particularly preferred. Moreover, these may be used individually or in combination of 2 or more types.

The (meth)acrylate copolymer (A) is preferably an alkyl (meth)acrylate having 1 to 20 carbon atoms containing 40% by mass or more of an alkyl group as a monomer unit constituting the polymer. 50 mass % or more is especially preferable, and it is more preferable to contain 60 mass % or more. When 40 mass % or more of alkyl (meth)acrylates are contained, suitable adhesiveness can be imparted to the (meth)acrylate copolymer (A). Moreover, it is preferable to contain 90 mass % or less of alkyl (meth)acrylates with an alkyl carbon number of 1-20, it is especially preferable to contain 80 mass % or less, and it is more preferable to contain 70 mass %. By making content of alkyl (meth)acrylate 90 mass % or less, the other monomer component of a required amount can be introduce|transduced into (meth)acrylate copolymer (A).

The (meth)acrylate copolymer (A) preferably contains a monomer having an alicyclic structure in the molecule (an alicyclic structure-containing monomer) as a monomer unit constituting the copolymer. Since the unit containing an alicyclic structure has a high volume, it is presumed that by making it exist in the polymer, the distance between the polymers can be widened, and the resulting adhesive can be provided with excellent flexibility. Therefore, the (meth)acrylate polymer (A) is an adhesive obtained by crosslinking the adhesive composition P using an alicyclic structure-containing monomer as a constituent monomer unit, and has a more excellent initial stage. Stage difference follower.

The carbocycle of the alicyclic structure of the alicyclic structure-containing monomer may be a saturated structure or may have an unsaturated bond in a part. In addition, the alicyclic structure may be a monocyclic alicyclic structure, or may be a polycyclic alicyclic structure such as bicyclic and tricyclic. The above-mentioned alicyclic structure is a polycyclic alicyclic structure from the viewpoint of increasing the distance between the obtained (meth)acrylate copolymers (A) and effectively exhibiting the flexibility of the adhesive. structure (polycyclic structure) is preferred. Furthermore, considering the compatibility between the (meth)acrylate copolymer (A) and other components, the above-mentioned polycyclic structure is particularly preferred to be bicyclic to tetracyclic. Also, in the same manner as above, from the viewpoint of effectively exerting the softening effect of the adhesive, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in the part forming the ring, and when a plurality of rings exist independently, Refers to the total carbon number) is usually 5 or more preferably, and particularly preferably 7 or more. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but in the same manner as described above, from the viewpoint of compatibility, it is preferably 15 or less, and particularly preferably 10 or less.

The alicyclic structure includes, for example, a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, an isocamphenyl skeleton, a cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, Cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.), cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornanediene skeleton, cubic alkane ( cubane) skeleton, basketane (Basketane) skeleton, house alkane (Housane) skeleton, spiro skeleton, etc., especially those containing dicyclopentadiene skeleton (alicyclic structure carbon number: 10) which exhibits more excellent durability ), adamantane skeleton (carbon number of alicyclic structure: 10), or isocamphenyl skeleton (carbon number of alicyclic structure: 7), and those containing an isocamphenyl skeleton are particularly preferred.

The above-mentioned alicyclic structure-containing monomer is preferably a (meth)acrylate monomer containing the above-mentioned skeleton, and specific examples thereof include cyclohexyl (meth)acrylate and di(meth)acrylate. Cyclopentyl, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc., especially Dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate or isobornyl (meth)acrylate are preferred, and isobornyl (meth)acrylate is particularly preferred . These may be used individually by 1 type, and may be used in combination of 2 or more types.

When the (meth)acrylate copolymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the (meth)acrylate copolymer (A) contains 5 mass % The above units containing an alicyclic structure are preferably contained, particularly preferably 8% by mass or more, and more preferably 10% by mass or more. In addition, the (meth)acrylate copolymer (A) preferably contains 40 mass % or less of an alicyclic structure-containing monomer as a monomer unit constituting the polymer, particularly 30 mass % or less. It is preferable, and it is more preferable to contain 20 mass % or less. When the content of the unit containing an alicyclic structure is in the above-mentioned range, the initial step followability of the obtained adhesive becomes more excellent.

The (meth)acrylate copolymer (A) preferably contains a monomer having a nitrogen atom in the molecule (a nitrogen atom-containing monomer) as a monomer unit constituting the copolymer. In addition, the amine group-containing monomer exemplified as the reactive group-containing monomer is assumed to be removed from the nitrogen atom-containing monomer. By having a nitrogen atom-containing monomer in the polymer as a structural unit, the reaction between the acrylate copolymer (A) and the thermal crosslinking agent (B) can be accelerated, or the adhesive can be imparted with polarity and the cohesive force of the adhesive itself can be improved. .

Examples of the above-mentioned nitrogen atom-containing monomers include monomers having a tertiary amine group, monomers having an amide group, monomers having a nitrogen-containing heterocycle, and the like, especially monomers having a nitrogen-containing heterocycle. Body is good.

As the monomer having a nitrogen-containing heterocycle, for example, N-(meth)acryloyl morpholinone, N-vinyl-2-pyrrolidone, and N-(meth)acryloylpyrrolidone can be mentioned. , N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, (meth)acryloyl ethyl aziridine, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc., especially for better adhesion N-(meth)acryloyl molyfrin is preferable, and N-acrylo molyfrin is preferable.

In addition, as a nitrogen atom-containing monomer other than the above-mentioned nitrogen-containing heterocyclic monomer, for example, (meth)acrylamide, N-methyl(meth)acrylamide, N-methylol can also be used Ethyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-ethyl(meth)acrylamide Amine, N,N-Dimethylaminopropyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-phenyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, N-vinylcaprolactam, (meth)acrylate dimethylamine ethyl, etc. The above nitrogen atom-containing monomers may be used alone or in combination of two or more.

When the (meth)acrylate copolymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the (meth)acrylate copolymer (A) contains 1 mass % or more of the The monomer of nitrogen atom is preferable, and it is especially preferable to contain 2 mass % or more, and it is more preferable to contain 5 mass % or more. In addition, the (meth)acrylate copolymer (A) preferably contains 40 mass % or less of a nitrogen atom-containing monomer as a monomer unit constituting the polymer, particularly preferably 25 mass % or less, Furthermore, it is preferable to contain 15 mass % or less. When the content of the nitrogen atom-containing monomer is within the above range, the cohesive force of the obtained adhesive is effectively improved.

The (meth)acrylate copolymer (A) may contain other monomers as a monomer unit constituting the polymer as needed. As other monomers, those containing a non-reactive functional group are preferable. Examples of such other monomers include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, benzene Ethylene etc. These may be used alone or in combination of two or more.

The polymerization aspect of the (meth)acrylate copolymer (A) may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 100,000 or more, particularly preferably 200,000 or more, and more preferably 300,000 or more. When the lower limit value of the weight average molecular weight of the (meth)acrylate polymer (A) is the above or more, the film strength of the obtained adhesive becomes the higher one. The upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 900,000 or less, particularly preferably 800,000 or less, and more preferably 700,000 or less. When the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is the above-mentioned or less, the step followability of the obtained adhesive becomes more excellent. In addition, the weight average molecular weight in this specification is the value in terms of standard polystyrene measured by the gel permeation chromatography (GPC) method.

Moreover, in the adhesive composition P, (meth)acrylate copolymer (A) may be used individually by 1 type, and may be used in combination of 2 or more types.

(2) Thermal crosslinking agent (B) When the adhesive composition P containing the thermal crosslinking agent (B) is heated, the thermal crosslinking agent (B) crosslinks the (meth)acrylate copolymer (A) and forms a three-dimensional network structure. Thereby, the adhesive layer 11 with high film strength can be obtained.

As said thermal crosslinking agent (B), what is necessary is just to react with the reactive group which the (meth)acrylate copolymer (A) has, for example, an isocyanate type crosslinking agent and an epoxy type crosslinking agent are mentioned. , Amine-based cross-linking agent, melamine-based cross-linking agent, aziridine-based cross-linking agent, hydrazine-based cross-linking agent, aldehyde-based cross-linking agent, oxazoline-based cross-linking agent, metal alkoxide-based cross-linking agent, Metal chelate-based cross-linking agents, metal salt-based cross-linking agents, ammonium-based cross-linking agents, etc. Among the above, when the reactive group possessed by the (meth)acrylate copolymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. When the reactive group which the copolymer (A) has is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group. Moreover, a thermal crosslinking agent (B) can be used individually by 1 type, or in combination of 2 or more types.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and isophorone. Alicyclic polyisocyanates such as diisocyanates and hydrogenated diphenylmethane diisocyanates, etc., and biuret compounds and triisocyanate compounds thereof, and further ethylene glycol, propylene glycol, neopentylerythritol, and trimethylolpropane , castor oil, etc. and the adducts of reactants containing low molecular active hydrogen compounds, etc. In particular, from the viewpoint of reactivity with hydroxyl groups, aromatic polyisocyanates modified with trimethylolpropane, especially trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified benzene diisocyanates. Methyl diisocyanate is preferred.

Examples of epoxy-based crosslinking agents include 1,3-bis(N,N-diglycidaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m Xylylenediamine, Ethylene Glycol Diglycidyl Ether, 1,6-Hexanediol Diglycidyl Ether, Trimethylolpropane Diglycidyl Ether, Diglycidylaniline, Bicyclo Oxypropylamine, etc. In particular, from the viewpoint of reactivity with a carboxyl group, 1,3-bis(N,N-diglycidaminomethyl)cyclohexane is preferable.

With respect to 100 parts by mass of the (meth)acrylate copolymer (A), the content of the thermal crosslinking agent (B) in the adhesive composition P is preferably 0.01 part by mass or more, preferably 0.05 part by mass or more Particularly preferred, and more preferably 0.1 part by mass or more. Moreover, this content is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and more preferably 0.4 parts by mass or less. When the content of the thermal crosslinking agent (B) is in the above-mentioned range, the obtained adhesive system has sufficient flexibility, exhibits good cohesive force, and can obtain the adhesive layer 11 with high film strength.

(3) UV curable component (C) When the adhesive composition P contains the ultraviolet curable component (C), the formed adhesive layer 11 becomes an ultraviolet curable adhesive layer. After the adhesive layer 11 is attached to the adherend, it is cured by irradiating ultraviolet rays, and it is presumed that the ultraviolet curable components (C) are polymerized with each other, and the polymerized ultraviolet curable components (C) are entangled in (A) base) the crosslinked structure (three-dimensional network structure) of the acrylate copolymer (A). Adhesives with such a high-dimensional structure have excellent step followability and foaming resistance under high temperature and high humidity conditions.

The ultraviolet curable component (C) is cured by irradiating ultraviolet rays in the presence of a photopolymerization initiator (D) described later, and is not particularly limited as long as it can obtain the above-mentioned effects, and may be monomeric, oligomeric Either the polymer or the polymer may be a mixture of these. In particular, a polyfunctional acrylate-based monomer having a molecular weight of less than 1,000 and having excellent compatibility with the (meth)acrylate copolymer (A) and the like can be suitably used.

Examples of polyfunctional acrylate-based monomers having a molecular weight of less than 1,000 include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyldiol Alcohol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxytrimethylacetate neopentyl glycol di(meth)acrylate Acrylate, dicyclopentenyl di(meth)acrylate, caprolactone modified dicyclopentene di(meth)acrylate, ethylene oxide modified phosphoric acid di(meth)acrylate, di(meth)acrylate Acryloyloxyethyl) isocyanate, allyl cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-propenyloxy) 2-functional type of ethoxy) phenyl] stilbene, etc.; trimethylolpropane tri(meth)acrylate, dipivalerythritol tri(meth)acrylate, propionic acid-modified dipivalerythritol Tri(meth)acrylate, neotaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, trimeric isocyanate (acryloyloxyethyl) Tri-functional type such as bis(2-(meth)acryloyloxyethyl) ester, ε-caprolactone-modified trimeric isocyanate (2-(meth)acryloyloxyethyl)ester; diglycerol tetra(meth)acrylate, neopentyl Four-functional type such as tetraol tetra(meth)acrylate; 5-functional type such as propionic acid-modified dipivalerythritol penta(meth)acrylate; dipivalerythritol hexa(meth)acrylate, Caprolactone-modified dipivoerythritol hexa(meth)acrylate etc. hexafunctional type etc. Among the above, from the viewpoint of step followability and foaming resistance of the obtained adhesive under high temperature and high humidity conditions, it is based on bis(acryloyloxyethyl) isocyanate, ginseng (acrylooxyethyl) Polyfunctional acrylate-based monomers containing a trimeric isocyanate structure in the molecule, such as ethyl) isocyanate and ε-caprolactone-modified gins (2-(meth)acrylooxyethyl) isocyanate Preferably, the polyfunctional acrylate-based monomer with more than 3 functions and a trimeric isocyanate structure in the molecule is preferable, and ε-caprolactone modified trimeric isocyanate (2-(meth)propylene) is preferred. Acetyloxyethyl) esters are particularly preferred. These may be used individually by 1 type, and may be used in combination of 2 or more types.

As the ultraviolet curable component (C), an ultraviolet curable acrylate-based oligomer can be used. The acrylate-based oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, poly Silicone acrylate, etc.

The weight average molecular weight of the acrylate-based oligomer is preferably 50,000 or less, preferably 500 to 50,000, and more preferably 3,000 to 40,000. These acrylate-based oligomers may be used alone or in combination of two or more.

Moreover, as an ultraviolet curable component (C), the addition acrylate type polymer which introduced the group which has a (meth)acryloyl group to a side chain can also be used. Such an addition acrylate-based polymer can be obtained by using a (meth)acrylate and a copolymer of a monomer having a crosslinkable functional group in the molecule, and further having a (meth)acryloyl group. The compound which reacts with the crosslinkable functional group is obtained by reacting a part of the crosslinkable functional group of the copolymer.

The weight average molecular weight of the above-mentioned addition acrylate polymer is preferably about 50,000 to 900,000, and particularly preferably about 100,000 to 500,000.

The ultraviolet curable component (C) can be used singly selected from the above-mentioned polyfunctional acrylate-based monomers, acrylate-based oligomers, and addition acrylate-based polymers, or two types can be combined. The above-mentioned use can also be used in combination with ultraviolet curable components other than these.

The content of the ultraviolet curable component (C) in the adhesive composition P is relatively high from the viewpoint that the obtained adhesive has excellent step followability and foaming resistance under high temperature and high humidity conditions. With respect to 100 parts by mass of the (meth)acrylate copolymer (A), it is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and particularly preferably 3 parts by mass or more. On the other hand, from the viewpoint of preventing the cross-linking from becoming too tight, resulting in low adhesion and poor durability, the above-mentioned content is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and 10 parts by mass The following are excellent.

(4) Photopolymerization initiator (D) In the photopolymerization initiator (D) of the present embodiment, the absorbance at a wavelength of 380 nm of an acetonitrile solution having a concentration of 0.1 mass % is 0.3 or more. Since the adhesive constituting the adhesive layer 11 contains such a photopolymerization initiator (D), even when the adhesive layer 11 is irradiated with ultraviolet rays through the display constituting member containing the ultraviolet absorber, the adhesive layer 11 (ultraviolet rays) The curable component (C)) hardens well and has excellent step followability and foaming resistance under high temperature and high humidity conditions.

From the above-mentioned viewpoints, the absorbance at a wavelength of 380 nm of the photopolymerization initiator (D) is preferably 0.5 or more, particularly preferably 1.0 or more. The upper limit of the absorbance is not particularly limited, but usually 2.5 or less is preferable, and 2.0 or less is particularly preferable. When the absorbance is greater than 2.5, the ultraviolet curable component (C) undergoes a curing reaction due to the photopolymerization initiator (D) in accordance with the ambient light of a fluorescent lamp during the formation or storage of the adhesive sheet, and then there is a A situation where the step followability is low. Here, the method for measuring the absorbance of the photopolymerization initiator (D) is disclosed in the test example described later.

In addition, the photopolymerization initiator (D) is the absorption maximum wavelength of the absorbance at the wavelength of 200 to 500 nm of the acetonitrile solution with a concentration of 0.1 mass %, preferably 350 nm or more, particularly preferably 370 nm or more, and more preferably 380 nm or more. good. In addition, when there are plural absorption maximum wavelengths of absorbance at a wavelength of 200 to 500 nm, at least one absorption maximum wavelength may be within the above-mentioned range. Thereby, when the adhesive layer 11 is irradiated with ultraviolet rays through the display constituent member containing the ultraviolet absorber, the curability of the adhesive layer 11 (ultraviolet curable component (C)) is further improved, and the adhesive layer 11 becomes a high-temperature and high-humidity condition. It has more excellent step followability and foam resistance. On the other hand, the upper limit of the absorption maximum wavelength is not particularly limited, but from the viewpoint of preventing the hardening reaction when the adhesive layer 11 is stored in ambient light, it is preferably 450 nm or less, and particularly preferably 410 nm or less. , and more preferably 405nm or less.

Examples of such a photopolymerization initiator (D) include 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzyl) acyl)-phenylphosphine oxide, etc. These may be used alone or in combination of two or more.

In addition, in the adhesive (adhesive composition P) of the present embodiment, the photopolymerization initiator (D) and the photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm at a concentration of 0.1 mass % of an acetonitrile solution of less than 0.3 may be photopolymerized. An initiator (hereinafter referred to as "photopolymerization initiator (ND)") is used together. Such a photopolymerization initiator (ND) includes, for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethyl ketone Oxy-1,2-diphenylethan-1-one, etc. In this case, the ratio of the photopolymerization initiator (ND) is preferably 50 to 150 parts by mass, particularly preferably 75 to 125 parts by mass, and further preferably 80 parts by mass relative to 100 parts by mass of the photopolymerization initiator (D). ~120 parts by mass is preferred.

The photopolymerization initiator (D) is used in an amount of 2 to 15 parts by mass with respect to 100 parts by mass of the ultraviolet curable component (C), and is particularly preferably used in an amount in the range of 4 to 12 parts by mass.

(5) Silane coupling agent (E) The adhesive composition P preferably further contains a silane coupling agent (E). Thereby, when the to-be-adhered object has a glass member, the adhesiveness of the obtained adhesive agent and this glass member improves. In addition, even if the adherend is a plastic board, the obtained adhesive system has improved adhesion to the plastic board. Thereby, the obtained adhesive becomes one which has more excellent step followability under high temperature and high humidity conditions.

The silane coupling agent (E) is an organosilicon compound having at least one alkoxysilyl group in the molecule, and one having good compatibility with the (meth)acrylate copolymer (A) and having light transmittance is good.

Examples of such a silane coupling agent (E) include polymerizable unsaturated group-containing silicon such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloyloxypropyltrimethoxysilane. Compounds, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and other silicon compounds with epoxy structure, 3-hydrothiopropyl Trimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane and other silicon compounds containing mercapto, 3-aminopropyltrimethoxysilane , N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and other silicon compounds containing amino groups , 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of these, together with methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane Condensates of alkyl-containing silicon compounds such as ethyl silane, ethyl trimethoxy silane, etc. These may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the silane coupling agent (E) in the adhesive composition P is based on 100 parts by mass of the (meth)acrylate copolymer (A), preferably 0.01 part by mass or more, particularly 0.05 part by mass or more Preferably, it is more preferably 0.1 part by mass or more. Moreover, this content is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, and more preferably 0.3 part by mass or less.

(6) Various additives In the adhesive composition P, various additives commonly used in acrylic adhesives, such as ultraviolet absorbers, antistatic agents, adhesion imparting agents, antioxidants, light stabilizers, softeners, fillers, Refractive index modifier, etc. In addition, the polymerization solvent and diluting solvent mentioned later are assumed to be additives that are not included in the adhesive composition P.

(7) Manufacture of adhesive composition Adhesive composition P is produced by (meth)acrylate copolymer (A), and the obtained (meth)acrylate copolymer (A), thermal crosslinking agent (B), ultraviolet curable component ( It can also be manufactured by adding a silane coupling agent (E) and/or an additive as needed while mixing C) and the photopolymerization initiator (D).

The (meth)acrylate copolymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a normal radical polymerization method. The polymerization of the (meth)acrylate copolymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as necessary. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. are mentioned, for example, You may use 2 or more types together.

As a polymerization initiator, an azo compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane Alkane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile) ), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2 -Hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], etc.

Examples of organic peroxides include benzyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, and di-n-propyl peroxydicarbonate. , Di(2-ethoxyethyl) peroxydicarbonate, 3-butyl peroxyneodecanoate, 3-butyl peroxytrimethyl acetate, (3,5,5-trimethyl peroxide) Hexyl alcohol), dipropylene peroxide, diacetyl peroxide, etc.

In addition, in the above-mentioned polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-hydrothioethanol.

After the (meth)acrylate copolymer (A) is obtained, the thermal crosslinking agent (B), the ultraviolet curable component (C), and the photopolymerization are added to the solution of the (meth)acrylate copolymer (A). The starting agent (D), the silane coupling agent (E) and the additives according to need are sufficiently mixed to obtain the adhesive composition P.

(8) Formation of the adhesive layer The adhesive layer 11 is obtained by thermally crosslinking the adhesive composition P. That is, the cross-linking of the adhesive composition P is performed by the heat treatment. In addition, the drying treatment after the application of the adhesive composition P may be performed concurrently with the heat treatment.

The heating temperature of the heat treatment is preferably 50 to 150°C, and particularly preferably 70 to 120°C. In addition, the heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes. Furthermore, it is particularly preferable to set the aging period at room temperature (for example, 23° C., 50% RH) for about 1 to 2 weeks after the heat treatment.

By the above-mentioned heat treatment (and aging), the (meth)acrylate copolymer (A) can be favorably crosslinked through the thermal crosslinking agent (B).

The thickness of the adhesive layer 11 (value measured according to JIS K7130) is preferably 20 μm or more, more preferably 25 μm or more, particularly preferably 30 μm or more, and more preferably 50 μm or more as the lower limit. When the lower limit value of the thickness of the adhesive layer 11 is 20 μm or more, the required adhesive force is likely to be exhibited. Moreover, when the lower limit value of the thickness of the adhesive layer 11 is 30 micrometers or more, sufficient level difference followability can be ensured with respect to the normal level difference of a display body structural member.

In addition, as an upper limit, the thickness of the adhesive layer 11 is preferably 500 μm or less, more preferably 400 μm or less, and particularly preferably 300 μm or less. When the upper limit of the thickness of the adhesive layer 11 is the above-mentioned or less, the workability is good. In addition, the adhesive layer 11 may be formed by a single layer, or may be formed by laminating a plurality of layers.

(9) Gel fraction (before UV irradiation) The lower limit of the gel fraction of the adhesive (before ultraviolet irradiation) constituting the adhesive layer 11 is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more. When the lower limit value of the gel fraction of the adhesive before ultraviolet irradiation is the above-mentioned or more, the cohesive force of the adhesive layer 11 is improved and the film strength is higher. The upper limit of the gel fraction of the adhesive before ultraviolet irradiation is preferably 70% or less, particularly preferably 65% or less, and more preferably 60% or less. When the upper limit of the gel fraction of the adhesive before ultraviolet irradiation is not more than the above, the adhesive does not become excessively hard, and the initial step followability becomes more excellent. The method for measuring the gel fraction of the adhesive (before ultraviolet irradiation) is disclosed in the test example described later.

2. Peel off sheet As the release sheets 12a and 12b, for example, polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyparaphenylene films can be used. Ethylene dicarboxylate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene·(meth)acrylic acid copolymer Film, ethylene·(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Moreover, these crosslinked films can also be used. Furthermore, these laminated films may be used.

It is preferable to perform a peeling process on the peeling surface (especially the surface contacting the adhesive layer 11) of the said peeling sheets 12a and 12b. Examples of the release agent used in the release treatment include alkyd-based, polysiloxane-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. In addition, among the release sheets 12a and 12b, one of the release sheets is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a smaller release force. good.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

3. Adhesive sheet manufacturing As one production example of the adhesive sheet 1, the coating liquid of the adhesive composition P described above is applied to the release surface of one release sheet 12a (or 12b), and heat treatment is performed to heat the adhesive composition P. After forming the coating layer in combination, the release surface of the other release sheet 12b (or 12a) is superimposed on the coating layer. When the above-mentioned coating layer requires an aging period, it is left to stand for the aging period, and when the aging period is not required, it directly becomes the adhesive layer 11 . Thereby, the above-mentioned adhesive sheet 1 can be obtained. The conditions for heat treatment and aging are as described above.

As another production example of the adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the release surface of one release sheet 12a, and heat-treated to thermally crosslink the adhesive composition P to form a coating The coating layer-attached release sheet 12a is obtained by distributing the layers. Then, the coating liquid of the above-mentioned adhesive composition P is applied to the peeling surface of the other peeling sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer to obtain a coating layer. the release sheet 12b. Then, the release sheet 12a with a coating layer and the release sheet 12b with a coating layer are attached together so that the two coating layers are in contact with each other. The above-described laminated coating layer is left to stand for the aging period when the aging period is required, and becomes the adhesive layer 11 directly when the aging period is not required. Thereby, the above-mentioned adhesive sheet 1 can be obtained. According to this manufacturing example, even when the adhesive layer 11 is thick, it can be manufactured stably.

As a method of applying the coating liquid of the above-mentioned adhesive composition P, for example, a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. can be used. .

In the adhesive sheet 1 of the present embodiment, since the film strength of the adhesive layer 11 is high, when the adhesive sheet 1 is cut, etc., it can be suppressed that the adhesive is extruded at the cross-section and the adhesive is adhered to the blade or the like. The problem. Furthermore, the bleeding of the adhesive from the adhesive layer 11 can also be suppressed during storage of the adhesive sheet 1 or the like.

[display body] As shown in FIG. 2, the display body 2 of the present embodiment is composed of the following: a first display body constituting member 21 (a display body constituting member) having a level difference at least on the surface on the side to be bonded; a second display body The constituent member 22 (other display body constituent member); and the cured adhesive layer 11 ′, which is located between them and adheres the first display body constituent member 21 and the second display body constituent member 22 to each other. In the display body 2 of the present embodiment, the first display body constituent member 21 has a level difference on the surface on the side of the adhesive layer 11' after curing, specifically, a level difference formed by the printing layer 3 .

The adhesive layer 11' of the above-mentioned display body 2 after curing is formed by curing the adhesive layer 11 of the above-mentioned adhesive sheet 1 by ultraviolet irradiation. The cured adhesive layer 11 ′ firstly has a cross-linked structure composed of a (meth)acrylate copolymer (A) and a thermal cross-linking agent (B), and is composed of an ultraviolet curable component (C ) of the cured product (polymer) and the adhesive of the photopolymerization initiator (D). It is presumed that the ultraviolet curable component (C) after polymerization is entangled in a crosslinked structure composed of the (meth)acrylate copolymer (A) and the thermal crosslinking agent (B).

The photopolymerization initiator (D) contained in the adhesive constituting the above-mentioned cured adhesive layer 11 ′, and the photopolymerization initiator (D) contained in the adhesive composition P, are not effective even when irradiated with ultraviolet rays. cracked and remained. Therefore, the content thereof is not much, and is usually 0.00001 mass % or more and 0.1 mass % or less, preferably 0.0001 mass % or more and 0.01 mass % or less in the adhesive.

The said cured adhesive layer 11 ′ has a second cross-linked structure composed of the (meth)acrylate copolymer (A) and the thermal cross-linking agent (B), and is composed of an ultraviolet curable component (C). ) of the adhesive of the cured product, and the gel fraction of the adhesive (after ultraviolet irradiation) is preferably 40% or more and 95% or less. Compared with the gel fraction of the adhesive constituting the adhesive layer 11 before UV curing, the gel fraction of the adhesive constituting the adhesive layer 11' after curing is the ultraviolet curable component (C) cured by ultraviolet rays become higher.

When the adhesive layer 11 is irradiated with ultraviolet rays over a display component that does not contain an ultraviolet absorber, the gel fraction of the adhesive constituting the adhesive layer 11' after curing is preferably 65% or more as a lower limit. , with more than 70% as the best. In addition, when the adhesive layer 11 is irradiated with ultraviolet rays over the display constituent member containing the ultraviolet absorber, the gel fraction of the adhesive constituting the adhesive layer 11' after curing is 40% or more as the lower limit. Good, more than 60% is more preferred, and more than 62% is particularly preferred. When the lower limit value of the gel fraction of the adhesive after ultraviolet irradiation is more than the above, the step followability and foaming resistance under the high temperature and high humidity conditions of the adhesive layer 11 ′ after curing of the display body 2 are relatively low. Excellent.

On the other hand, when the adhesive layer 11 is irradiated with ultraviolet rays over the display constituent member that does not contain an ultraviolet absorber, the gel fraction of the adhesive constituting the adhesive layer 11' after curing is set to 90 as the upper limit. % or less is preferable, 85% or less is particularly preferable, and 80% or less is more preferable. In addition, when the adhesive layer 11 is irradiated with ultraviolet rays beyond the display constituent member containing the ultraviolet absorber, the gel fraction of the adhesive constituting the adhesive layer 11' after curing is 90% or less as the upper limit. Preferably, 80% or less is particularly preferred, and more preferably 75% or less. When the upper limit of the gel fraction of the adhesive after ultraviolet irradiation is equal to or lower than the above, it is possible to prevent the adhesive force of the adhesive layer 11' after curing from decreasing and the durability from deteriorating. The method for measuring the gel fraction of the adhesive (after ultraviolet irradiation) is as disclosed in the test examples described later.

The step following rate (%) represented by the following formula of the adhesive layer 11' after curing is preferably 20% or more, particularly preferably 25% or more, and more preferably 30% or more as the lower limit. In addition, the upper limit value of the step tracking rate is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less. Step follow-up rate (%)={(After the scheduled durability test, there is no bubble, floating, peeling, etc., and the step height (μm) can be maintained in a buried state)/(The thickness of the adhesive layer)}×100 In addition, the test method of the step following rate is disclosed as a test example to be described later.

With the step following ratio of the adhesive layer 11 ′ after curing in the above-mentioned range, the adhesive layer 11 ′ after curing can follow the step difference of the display body constituent member (the first display body constituent member 21 ) well even after the durability test and can The generation of air bubbles, floating, peeling, etc. in the vicinity of the level difference can be suppressed, and the reflection loss of the light caused by this can be suppressed.

As the display body 2, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, etc. are mentioned, for example, and a touch panel may be sufficient as it. Moreover, as the display body 2, the member which comprises a part of these may be sufficient.

In addition to a glass plate, a plastic plate, and the like, the first display body constituting member 21 is preferably a protective panel composed of a laminate or the like including these. At this time, the printed layer 3 is usually formed in a frame shape on the side of the adhesive layer 11' after curing of the first display body constituent member 21.

The first display body constituent member 21 , especially the first display body constituent member 21 serving as the protective panel, preferably contains an ultraviolet absorber. At this time, the display body 2 has excellent light resistance, and even if the manufactured display body 2 is exposed to ultraviolet rays from the side of the first display body constituent member 21 , the adhesive layer 11 ′ and the lower layer after curing can be suppressed from being damaged. The second display body constituent member 22 deteriorates. In particular, the adhesive layer 11' can maintain excellent step followability and blister resistance well after curing.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium boron Silicon glass etc. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

Although it does not specifically limit as said plastic plate, For example, an acrylic board, a polycarbonate board, etc. are mentioned. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

In addition, various functional layers (transparent conductive films, metal layers, silicon oxide layers, hard coat layers, anti-glare layers, etc.) may be provided on one or both surfaces of the glass plate and the plastic plate, and optical members may be laminated. Moreover, a transparent conductive film and a metal layer may be patterned.

The second display body structuring member 22 is an optical member to be attached to the first display body structuring member 21, and is a display body module (eg, a liquid crystal (LCD) module, a light emitting diode (LED) module , organic electroluminescence (organic EL) modules, etc.), optical components that are part of the display module, or laminates including the display module are preferred. Also, display module systems generally do not transmit ultraviolet rays.

Examples of the optical member include anti-scattering films, polarizers (polarizing films), polarizers, retardation films (retardation films), viewing angle compensation films, brightness enhancement films, contrast enhancement films, liquid crystal polymer films, Diffusion film, semi-transmissive reflection film, transparent conductive film, etc. As an anti-scattering film, the hard-coat film etc. which formed a hard-coat layer on one surface of a base film can be illustrated. The said optical member may contain an ultraviolet absorber.

The material constituting the printing layer 3 is not particularly limited, and conventional materials for printing can be used. The thickness of the printed layer 3, that is, the lower limit of the height of the step, is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. By setting the lower limit value to be equal to or greater than the above, it is possible to sufficiently secure the shielding properties that prevent the circuit or the like from being seen from the viewer's side. In addition, the upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and more preferably 20 μm or less. By setting the upper limit to the above-mentioned or lower value, it is possible to prevent the adhesive layer 11' after curing from deteriorating the step followability of the printed layer 3 .

In the best form of the display body 2, the first display body constituent member 21 is a protective panel including a plastic plate containing an ultraviolet absorber, and the second display body constituent member 22 is a touch screen of a display module module that does not transmit ultraviolet rays panel. In addition, the patterned transparent conductive film and the metal layer may exist in any part. Such a display body 2 is excellent in all of light resistance, step followability, and foam resistance.

The above-mentioned display body 2 is manufactured, as an example, by peeling off the release sheet 12a of the adhesive sheet 1, and bonding the exposed adhesive layer 11 of the adhesive sheet 1 to the printed layer 3 of the first display body constituent member 21 There are side faces. In this case, since the adhesive layer 11 has excellent initial step followability, it is possible to suppress generation of gaps and floating in the vicinity of the step caused by the print layer 3 .

Next, the other peeling sheet 12b of the adhesive layer 11 of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second display component 22 to obtain a laminate. Moreover, as another example, the bonding order of the 1st display body structure member 21 and the 2nd display body structure member 22 may be changed.

Subsequently, ultraviolet rays are irradiated to the adhesive layer 11 in the above-mentioned laminate. Thereby, the ultraviolet curable component (C) in the adhesive layer 11 is polymerized and the adhesive layer 11 is hardened to become the hardened adhesive layer 11'. Irradiation of ultraviolet rays to the adhesive layer 11 is usually carried out over either the first display body constituting member 21 or the second display body constituting member 22, preferably over the first display body constituting member 21 as a protective panel. Here, even if the display element constituting member (preferably the first display element constituting member 21 serving as the protective panel) on the ultraviolet irradiated side contains an ultraviolet absorber, the photopolymerization contained in the adhesive constituting the adhesive layer 11 starts to polymerize. The initiator (D) is one whose absorbance at a wavelength of 380 nm is 0.3 or more, so that the ultraviolet rays of the wavelength used to crack the photopolymerization initiator (D) are not absorbed by the ultraviolet absorber in the display element constituting member, so that photopolymerization is carried out. The initiator (D) cracked without problems. As a result, the curing reaction of the ultraviolet curable component (C) proceeds favorably, and the adhesive layer 11 is sufficiently cured. Thereby, the obtained display body 2 has excellent step followability and foaming resistance under high temperature and high humidity conditions.

The irradiation of ultraviolet rays can be performed using a high-pressure mercury lamp, a Fusion H lamp, a xenon lamp, or the like, and the illuminance of the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW/cm ² . In addition, the amount of light is preferably 50 to 10000 mJ/cm ² , preferably 80 to 5000 mJ/cm ² , and particularly preferably 200 to 2000 mJ/cm ² .

In the above display body 2, since the cured adhesive layer 11' has excellent step followability even under high temperature and high humidity conditions, even if the display body 2 is placed under high temperature and high humidity conditions (for example, 85°C, 85% RH, 72 hours), generation of bubbles, floating, peeling, etc. in the vicinity of the level difference can also be suppressed.

In addition, in the above-mentioned display body 2, since the adhesive layer 11' after curing has excellent foaming resistance, the display body 2 is placed under high temperature and high humidity conditions (for example, 85°C, 85% RH, 72 hours), Even when outgassing is generated from the display element constituting member composed of a vinyl plate or the like, the generation of bubbles, floating, peeling, etc., can be suppressed at the interface between the adhesive layer 11 ′ and the display element constituting members 21 and 22 after curing. .

The embodiments described above are described in order to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, the gist of each element disclosed in the above-described embodiment also includes all design changes and equivalents that belong to the technical scope of the present invention.

For example, either of the peeling sheets 12a and 12b in the adhesive sheet 1 may be omitted. Moreover, the 1st display body structure member 21 may have a level difference other than the printing layer 3, and may not have a level difference. In addition, not only the first display body constituting member 21 but also the second display body constituting member 22 may have a level difference on the adhesive layer 11' side after curing. [Example]

Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the scope of the present invention is not limited by these Examples and the like.

[Example 1] 1. Preparation of (meth)acrylate copolymer (Methyl) was prepared by copolymerizing 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of N-acrylomorphine, and 20 parts by mass of 2-hydroxyethyl acrylate Acrylate copolymer (A). When the molecular weight of this (meth)acrylate copolymer (A) was measured by the method mentioned later, the weight average molecular weight (Mw) was 500,000.

2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylate copolymer (A) obtained in the above step 1 (solid content conversion value; the same below), trimethylolpropane-modified toluene diisocyanate as the thermal crosslinking agent (B) 0.2 parts by mass, ε-caprolactone-modified ginseng (2-propenyloxyethyl) isocyanate as ultraviolet curable component (C), 5.0 parts by mass, 2, as photopolymerization initiator (D) 0.5 parts by mass of 4,6-trimethylbenzyl-diphenyl-phosphine oxide, and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent (E) , product name "KBM-403") 0.3 parts by mass, mixed with sufficient stirring, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition with a solid content concentration of 50 mass %.

3. Manufacture of adhesive sheets The obtained coating solution of the adhesive composition was coated on the peeling-treated surface of a heavy-peeling release sheet (manufactured by LINTEC, product name "SP-PET752150") using a knife coater, wherein the heavy-peeling peeling The sheet is obtained by peeling off one side of a polyethylene terephthalate film using a polysiloxane-based release agent. Then, the coating layer was heat-treated at 90° C. for 1 minute to form a coating layer.

Next, the coating layer on the heavy release type release sheet obtained above, and the light release type release sheet (LINTEC The company's product, product name "SP-PET382120"), the peeling treatment surface of the light peeling type release sheet is attached so that the peeled surface is in contact with the coating layer, and by aging at 23 ° C and 50% RH for 7 days, and An adhesive sheet having an adhesive layer with a thickness of 50 μm, that is, an adhesive sheet consisting of a heavy release type release sheet/adhesive layer (thickness: 50 μm)/light release type release sheet was produced. In addition, the thickness of the adhesive layer is a value measured using a constant pressure thickness measuring device (manufactured by Teclock, product name "PG-02") in accordance with JIS K7130.

Here, Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth)acrylate copolymer (A) is taken as 100 parts by mass (solid content conversion value). In addition, the details of the abbreviations etc. described in Table 1 are as follows. [(Meth)acrylate Copolymer (A)] 2EHA: 2-ethylhexyl acrylate IBXA: Isobornyl Acrylate ACMO: N-acryloyl molyfrin HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate AA: Acrylic [Thermal crosslinking agent (B)] TDI series: Trimethylolpropane modified toluene diisocyanate Epoxy system: 1,3-bis(N,N-diglycidamine methyl)cyclohexane [Photopolymerization initiator (D)] D1: 2,4,6-Trimethylbenzyl-diphenyl-phosphine oxide D2: bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide D3: 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one in a mass ratio of 1:1 mixed D4: 1-Hydroxycyclohexyl phenyl ketone

[Examples 2 to 5, Comparative Examples 1 to 2] In addition to the types and proportions of the monomers constituting the (meth)acrylate copolymer (A), the types and amounts of the thermal crosslinking agent (B), the amount of ultraviolet curable components (C), and photopolymerization An adhesive sheet was produced in the same manner as in Example 1 except that the type and compounding amount of the initiator (D) were changed as shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is the weight average molecular weight in terms of standard polystyrene measured under the following conditions using gel permeation chromatography (GPC). <Measurement conditions> ‧GPC measurement device: HLC-8020 manufactured by TOSOH Corporation ‧GPC column (passed in the following order): manufactured by TOSOH TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL ‧Measurement solvent: tetrahydrofuran ‧Measurement temperature: 40℃

[Test Example 1] (Measurement of absorbance) An acetonitrile solution with a concentration of 0.1 mass % of the photopolymerization initiator used in the examples and comparative examples was prepared, and the absorbance in the wavelength range of 200 to 500 nm was used for the solution (manufactured by Shimadzu Corporation, product name "UV-3600") And measure. Based on the results, the absorption maximum wavelength (nm) of the absorbance at a wavelength of 380 nm and the absorbance at a wavelength of 200 to 500 nm was derived. The results are shown in Table 1.

[Test Example 2] (Measurement of gel fraction) The adhesive sheets obtained in the Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed using a precision balance. The mass of the adhesive alone is calculated by subtracting the mass of the above mesh alone. Let the mass at this time be M1.

Next, the adhesive covered by the polyester mesh was immersed in ethyl acetate at room temperature (23° C.) for 72 hours. Then, the adhesive was taken out and air-dried in an environment with a temperature of 23° C. and a relative humidity of 50% for 24 hours, and was further dried in an oven at 80° C. for 12 hours. After drying, the mass is weighed using a precision balance, and the mass of the adhesive alone is calculated by subtracting the mass of the above mesh alone. Let the mass at this time be M2. The gel fraction (%) is represented by (M2/M1)×100. Thereby, the gel fraction of the adhesive (before ultraviolet irradiation) was derived. The results are shown in Table 2.

On the other hand, a light peeling type release sheet was peeled off from the adhesive sheets obtained in the examples and comparative examples, and the exposed adhesive layer was directly irradiated with ultraviolet rays under the following conditions to harden the adhesive layer to form a post-hardening adhesive agent layer. The gel fraction (after ultraviolet irradiation; direct irradiation) was derived in the same manner as above with respect to the adhesive of the adhesive layer after curing. The results are shown in Table 2.

In addition, the light peeling type release sheet was peeled off from the adhesive sheets obtained in Examples and Comparative Examples, and the exposed adhesive layer was attached to a resin sheet (Mitsubishi) having a polymethyl methacrylate layer and a polycarbonate layer. The polycarbonate layer side surface of Gas Chemical Co., Ltd., product name "UPILON·SHEET MR-58U", thickness: 0.8mm, containing UV absorber). Next, the above-mentioned adhesive layer was irradiated with ultraviolet rays under the following conditions over the above-mentioned resin plate, and the adhesive layer was hardened to form a post-hardening adhesive layer. With respect to the adhesive of the adhesive layer after curing, the gel fraction was derived in the same manner as described above (after ultraviolet irradiation; irradiation over the resin plate). Moreover, the value obtained by subtracting the gel fraction after ultraviolet irradiation irradiated over the resin plate from the gel fraction after direct irradiation with ultraviolet rays was calculated. The results are shown in Table 2.

<Ultraviolet irradiation conditions> ‧Using high pressure mercury lamp ‧Illumination 200mW/cm ² , light intensity 2000mJ/cm ² ‧UV illuminance

[Test Example 3] (Evaluation of foaming resistance) A polyethylene terephthalate film (manufactured by Oike Kogyo Co., Ltd.) provided with a transparent conductive film made of indium tin oxide (ITO) on one side of the adhesive layer of the adhesive sheets obtained in the examples and comparative examples was used. , ITO film, transparent conductive film of thickness: 125μm), and resin plate with polymethyl methacrylate layer and polycarbonate layer (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "UPILON·SHEET MR-58U", thickness: 0.8mm, the surface on the polycarbonate layer side containing the ultraviolet absorber) is sandwiched. Subsequently, autoclave treatment was performed under the conditions of 50° C. and 0.5 MPa for 30 minutes, and left to stand at normal pressure, 23° C., and 50% RH for 24 hours.

The adhesive layer of the obtained laminated body was irradiated with ultraviolet rays under the same conditions as in Test Example 2 beyond the above-mentioned resin plate, and the adhesive layer was hardened to form a post-hardening adhesive layer. Next, it was stored for 72 hours under high temperature and high humidity conditions of 85°C and 85% RH. Then, the state of the interface between the adhesive layer and the adherend after curing was visually confirmed, and the foaming resistance was evaluated according to the following criteria. The results are shown in Table 2. ○...No bubbles, floating and peeling ×…Bubble, bubble trace or floating・Peeling

[Test Example 4] (Measurement 1 of step tracking rate) On the surface of a glass plate (manufactured by NSG PRECISION, product name "Corning Glass EAGLE XG", vertical 90 mm × horizontal 50 mm × thickness 0.5 mm), an ultraviolet curable ink ( Imperial Ink Co., Ltd., product name "POS-911 ink"), screen-printed into a frame shape (outline: vertical 90 mm x horizontal 50 mm, width 5 mm) so that the coating thickness is any of 25 μm, 30 μm, and 40 μm. Next, ultraviolet rays (80 W/cm ² , 2 metal halide lamps, 15 cm lamp height, and 10 to 15 m/min of conveyor speed) are irradiated with ultraviolet rays to harden the above-mentioned UV-curable ink after printing, to produce a step (step difference) by printing. height: any one of 25 μm, 30 μm and 40 μm) with a glass plate with a step difference.

The light peeling type release sheet was peeled off from the adhesive sheets obtained in Examples and Comparative Examples, and the exposed adhesive layer was attached to a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Product name "PET A4300", thickness: 100 μm) easily bonding layer. Next, peel off the heavy peeling type release sheet to expose the surface of the adhesive layer, and use a laminating machine (manufactured by Fujipla, product name "LPD3214") to cover the entire surface of the adhesive layer with the adhesive layer. The glass plate of the step difference is attached. Subsequently, autoclave treatment was performed under the conditions of 50° C., 0.5 MPa for 30 minutes and left to stand at normal pressure, 23° C., 50% RH for 24 hours.

The adhesive layer of the obtained laminate was irradiated with ultraviolet rays under the same conditions as in Test Example 2 over the polyethylene terephthalate film to harden the adhesive layer to obtain a post-hardening adhesive layer. Next, it was stored for 72 hours under high temperature and high humidity conditions of 85° C. and 85% RH (endurance test), and then, the step followability was evaluated. The level difference followability is judged by whether the adhesive layer after curing completely fills the printing level difference. When air bubbles, floating, peeling, etc. can be observed at the interface between the printing level difference and the cured adhesive layer, it is judged that the printing level difference cannot be followed. Segment difference. Here, the level difference followability was evaluated as a level difference follow rate (%) represented by the following formula. The results are shown in Table 2. In addition, the case where the level difference following rate of 50% cannot be satisfied is described as ×. Step follow-up rate (%)={(Height of step (μm) without air bubbles, floating, peeling, etc. and can maintain the buried state after durability test) / (thickness of adhesive layer: 50μm)}×100

[Test Example 5] (Measurement of step follow rate 2) In the same manner as in Test Example 4, a laminate obtained by sandwiching the adhesive sheet adhesive layers obtained in Examples and Comparative Examples using the above-mentioned glass plate with step and the above-mentioned polyethylene terephthalate film was obtained. On the polyethylene terephthalate film of the obtained laminated body (after the above autoclave treatment, it was left at normal pressure, 23° C., and 50% RH for 24 hours) with a polymethyl methacrylate layer on the polyethylene terephthalate film. and the polycarbonate layer of the resin sheet (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "UPILON·SHEET MR-58U", thickness: 0.8mm, containing an ultraviolet absorber) and its polycarbonate layer side surface and the above-mentioned polyparaphenylene Set in the way of surface contact of ethylene diformate film. Then, the above-mentioned adhesive layer was irradiated with ultraviolet rays under the same conditions as in Test Example 2 over the resin plate and the polyethylene terephthalate film to harden the adhesive layer to obtain a post-hardening adhesive layer. Subsequently, the above-mentioned resin plate was removed, and the same durability test and evaluation as in Test Example 4 were performed. The results are shown in Table 2.

[Test Example 6] (Evaluation of Light Resistance) A laminate was produced in the same manner as in Test Example 3 using the adhesive sheet obtained in the Example. The adhesive layer of the obtained laminate was irradiated with ultraviolet rays under the same conditions as in Test Example 2 over the above-mentioned resin plate to harden the adhesive layer to obtain a post-hardening adhesive layer. Subsequently, it was put into a light resistance tester (manufactured by SUGA Testing Machine Co., Ltd., product name "Ultraviolet Fade Meter U48", light source: carbon arc lamp) and irradiated with ultraviolet rays (illuminance: 50 mW/cm ² ) from the resin plate side for 100 hours. Then, when the state of the transparent conductive film of the laminated body was visually confirmed, no change was observed in the transparent conductive film.

On the other hand, except that the adhesive sheet of Comparative Example 2 was used and the resin sheet was changed to a polycarbonate resin sheet (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "HMRS51T") that did not contain an ultraviolet absorber, it was the same as that of Test Example 3. In the same manner, a layered body was produced. The adhesive layer of the obtained laminate was irradiated with ultraviolet rays under the same conditions as in Test Example 2 over the above-mentioned resin plate to cure the adhesive layer to obtain a post-curing adhesive layer. Subsequently, it was put into a light resistance tester (manufactured by SUGA Testing Machine Co., Ltd., product name "Ultraviolet Fade Meter U48", light source: carbon arc lamp), and irradiated with ultraviolet rays (illuminance: 50 mW/cm ² ) from the resin plate side for 100 hours. Then, when the state of the transparent conductive film of the laminated body was visually confirmed, discoloration was observed in the transparent conductive film.

[Table 1]

[Table 2]

As can be seen from Table 2, even when the adhesive layer obtained in the Example is irradiated with ultraviolet rays over the resin plate containing the ultraviolet absorber, as the adhesive layer after curing, the step followability and the lifting resistance under high temperature and high humidity conditions are Both foaming properties are excellent. industrial availability

The adhesive sheet of the present invention can be suitably used, for example, for lamination of a protective panel having a step and containing an ultraviolet absorber and a desired display body constituent member.

1: Adhesive board 11: Adhesive layer 12a, 12b: release sheet 2: Display body 11': Adhesive layer after hardening 21: Components of the first display body 22: Second display body component 3: Printing layer

Fig. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of a laminate according to an embodiment of the present invention.

1: Adhesive board

11: Adhesive layer

12a, 12b: release sheet

Claims (4)

A method of manufacturing a display, characterized in that: manufacturing a laminated body, which is an adhesive for connecting a display constituent member containing an ultraviolet absorber and other display constituent members through an adhesive sheet having an ultraviolet curable adhesive layer A layered product formed by laminating layers, wherein the UV-curable adhesive layer contains a photopolymerization initiator whose absorbance at a wavelength of 380 nm in an acetonitrile solution with a concentration of 0.1 mass % is 0.3 or more, and is displayed over one of the UV-absorbing agents. The body constituting member and the adhesive layer of the layered body are irradiated with ultraviolet rays to harden the adhesive layer to form a post-hardening adhesive layer. The method for producing a display body according to claim 1, wherein the adhesive constituting the adhesive layer has a gel fraction of not less than 30% and not more than 70%. The method for manufacturing a display body according to claim 1, wherein the one display body constituent member has a level difference at least on the surface on the side to be bonded. The method for producing a display body according to claim 1, wherein the cured adhesive layer has a gel fraction of 40% or more and 95% or less.

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