JP6270941B2 - Adhesive, adhesive sheet, and display body manufacturing method - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet for bonding display-body constituent members, and a method for manufacturing a display body using a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet.

  Various mobile electronic devices such as mobile phones and tablet terminals in recent years include a display body (display) using a display body module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like. Yes.

  In such a display, a protective panel is usually provided on the surface side of the display module. A gap is provided between the protection panel and the display module so that the deformed protection panel does not hit the display module even when the protection panel is deformed by an external force.

  However, if there is a gap as described above, that is, an air layer, the difference in refractive index between the protective panel and the air layer, and the reflection loss of light due to the difference in refractive index between the air layer and the display module is large. There is a problem that the image quality deteriorates.

  Therefore, it has been proposed 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, a frame-like printed layer may exist as a step on the display module side of the protective panel. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer floats in the vicinity of the step, thereby causing light reflection loss. For this reason, the pressure-sensitive adhesive layer is required to have a step following ability.

In order to solve the above-described problem, Patent Document 1 discloses that the shear storage elastic modulus (G ′) at 25 ° C. and 1 Hz is 1.0 as an adhesive layer that fills the gap between the protective panel and the display module. × is at 10 5 ^Pa or less, and a gel fraction discloses a pressure-sensitive adhesive layer is 40% or more.

JP 2010-97070 A

  In patent document 1, it is going to improve level | step difference followability by making low the storage elastic modulus at the time of normal temperature in an adhesive layer. As another method, it is conceivable to improve the step following property by lowering the degree of crosslinking of the heat-crosslinking type pressure-sensitive adhesive, that is, the gel fraction. However, when the storage elastic modulus and the gel fraction are lowered as described above, the coating strength of the pressure-sensitive adhesive layer is lowered, and the workability is deteriorated. For example, when the pressure sensitive adhesive sheet is punched out, a problem arises in that the pressure sensitive adhesive adheres to the blade and a part of the pressure sensitive adhesive layer is lost.

The present invention has been made in view of such a situation, and provides a pressure-sensitive adhesive and pressure-sensitive adhesive sheet having excellent step followability and high film strength, and a method for producing a display using the pressure-sensitive adhesive sheet. For the purpose.

In order to achieve the above object, first, the present invention is a pressure-sensitive adhesive for bonding one display member constituting member having a step on at least the surface to be bonded and another display member constituting member. der is, and I prior to adhesive der in contact with the display body components and other display-constituting member of the one, the adhesive is a reactive functional group-containing monomer as a monomer unit constituting a polymer and a containing (meth) acrylic acid ester polymer (a), using a bifunctional or more active energy ray-curable component (B), thermally crosslinkable crosslinking agent adhesive composition containing a (C) The (meth) acrylic acid ester polymer (A) contains a component crosslinked by the crosslinking agent (C) and a component formed by polymerizing the active energy ray-curable component (B). cage, wherein the active energy in the adhesive composition The content of ghee ray curing component (B), the (meth) acrylic acid ester polymer (A) with respect to 100 parts by weight, 0.1 parts by mass or more, or less 4 parts by mass, and thickness of 600μm When the pressure-sensitive adhesive layer has a width of 10 mm, the maximum stress is 2.8 N or more when stretched to the breaking elongation at a measurement length of 20 mm and a tensile speed of 200 mm / min in an environment of 23 ° C. and 50% RH. There is provided a pressure-sensitive adhesive (Invention 1).

  The pressure-sensitive adhesive according to the invention (Invention 1) satisfies the above-described conditions, thereby being excellent in step following ability and exhibiting high film strength.

  In the said invention (invention 1), it is preferable that the said gel fraction (G1) is 40 to 80% (invention 2).

  In the above inventions (Inventions 1 and 2), when the adhesive layer has a thickness of 600 μm and a width of 10 mm, when stretched at a measurement length of 20 mm and a tensile speed of 200 mm / min in an environment of 23 ° C. and 50% RH The elongation at break is preferably 1000% or more (Invention 3).

  In the said invention (invention 1-3), it is preferable that the weight average molecular weights of the said (meth) acrylic acid ester polymer (A) are 200,000-1 million (invention 4).

  In the said invention (invention 1-4), the said (meth) acrylic acid ester polymer (A) contains 5-30 mass% of said reactive functional group containing monomers as a monomer unit which comprises the said polymer. Preferred (Invention 5).

  In the said invention (invention 1-5), the reactive functional group of the said reactive functional group containing monomer is a carboxyl group and / or a hydroxyl group, and the said crosslinking agent (C) is an isocyanate type crosslinking agent and / or epoxy. A cross-linking agent is preferable (Invention 6).

  2ndly this invention provides the adhesive sheet which has an adhesive layer which consists of the said adhesive (invention 1-6) (invention 7).

  In the said invention (invention 7), it is preferable that the thickness of the said adhesive layer is 10-400 micrometers (invention 8).

  In the above inventions (Inventions 7 and 8), the pressure-sensitive adhesive sheet includes two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. (Invention 9)

3rdly, this invention is a method of manufacturing the display body provided with one display body structural member which has a level | step difference at the surface of the side bonded together, and another display body structural member , Comprising: The said adhesive sheet Provided is a method for manufacturing a display body , wherein the one display body constituent member and the other display body constituent member are bonded to each other using the pressure-sensitive adhesive layer of (Invention 7 to 9) (Invention). 10).

  In the said invention (invention 10), the said level | step difference may be frame shape in planar view (invention 11).

  The pressure-sensitive adhesive according to the present invention and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet are excellent in step following ability and exhibit high film strength. In the display obtained using such an adhesive sheet, when there is a step on the bonding surface side, the adhesive layer follows the step, and even after the endurance condition, the step and the adhesive It is difficult to form voids or bubbles between them, and the pressure-sensitive adhesive layer can maintain a state where the step is filled.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the laminated body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive]
The pressure-sensitive adhesive according to the present embodiment is a pressure-sensitive adhesive for bonding at least one display member constituting member having a step on the surface to be bonded and another display member forming member. A display body and a display body structural member are mentioned later.

  The pressure-sensitive adhesive according to this embodiment includes a (meth) acrylic acid ester polymer (A) containing a reactive functional group-containing monomer as a monomer unit constituting the polymer, and a bifunctional or higher functional energy ray-curable component (B). ) And a heat-crosslinkable crosslinking agent (C) (hereinafter, sometimes referred to as “adhesive composition P”) are thermally crosslinked and active energy ray cured. In such an adhesive, the (meth) acrylic acid ester polymer (A) is crosslinked by a crosslinking agent (C) to form a three-dimensional network structure, and the active energy ray-curable components (B) are polymerized with each other. It is presumed to be entangled with the three-dimensional network structure. Hereinafter, this structure may be referred to as “structure X”. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

  The content of the active energy ray-curable component (B) in the adhesive composition P includes the gel fraction (G1) of the adhesive according to the present embodiment and the active energy ray-curable component from the adhesive composition P. The gel fraction (G2) of the pressure-sensitive adhesive obtained by thermally crosslinking the pressure-sensitive adhesive composition excluding (B) (hereinafter sometimes referred to as “pressure-sensitive adhesive H”) is an amount that is substantially the same. . Here, “substantially the same” means that the gel fraction change rate shown below is at a level of 15% or less.

The gel fraction change rate is obtained by thermally crosslinking a pressure-sensitive adhesive composition obtained by removing the active energy ray-curable component (B) from the pressure-sensitive adhesive composition P by G1 (%). When the gel fraction of the pressure-sensitive adhesive H is expressed as G2 (%), it is represented by the following formula.
Gel fraction change rate (%) = {(G1-G2) / G2} × 100

  The pressure-sensitive adhesive according to this embodiment preferably has a gel fraction change rate of 0 to 15%, particularly preferably 0 to 10%, and more preferably 0 to 4%. In addition, the measuring method of a gel fraction is as showing to the test example mentioned later.

  Further, the adhesive according to the present embodiment has a breaking elongation at a measurement length of 20 mm and a tensile speed of 200 mm / min in an environment of 23 ° C. and 50% RH when the adhesive layer has a thickness of 600 μm and a width of 10 mm. It is necessary that the maximum stress when it is extended to 2.8 N or more. Thereby, the film intensity | strength which can prevent the glue chipping etc. of the adhesive layer at the time of a cutting | disconnection can be obtained. From the same viewpoint, the maximum stress is preferably 3N or more, particularly preferably 4N or more. On the other hand, the upper limit of the maximum stress is not particularly limited, but is preferably 7N or less, and particularly preferably 6N or less from the viewpoint of not deteriorating the step following rate. In addition, the specific method of this tensile test is as showing to the test example mentioned later. Such maximum stress is achieved when the adhesive composition P contains a predetermined amount of the active energy ray-curable component (B).

  In the pressure-sensitive adhesive according to this embodiment, the (meth) acrylic acid ester polymer is obtained by thermally crosslinking and curing the active energy ray of the pressure-sensitive adhesive composition P containing the active energy ray-curable component (B) in the above amount. It is presumed that the three-dimensional network structure formed by (A) and the crosslinking agent (C) forms a structure X in which the polymerized active energy ray-curable component (B) is entangled to such an extent that the gel fraction is not substantially changed. The With this structure X, the pressure-sensitive adhesive according to the present embodiment exhibits excellent stress relaxation properties and excellent step-following properties. Therefore, the adhesive according to the present embodiment satisfactorily follows the steps when bonding one display body constituent member having a step on the surface to be pasted and another display body constituent member. However, even after a predetermined durability condition, it is difficult to form a gap or a bubble between the step and the pressure-sensitive adhesive, and the pressure-sensitive adhesive layer can maintain a state in which the level difference is filled (hereinafter, after the predetermined durability condition). The step following ability may be simply referred to as “step following ability”. Further, due to the structure X described above, the pressure-sensitive adhesive according to the present embodiment exhibits high film strength. Therefore, for example, when the pressure-sensitive adhesive sheet is punched out, it is possible to suppress the occurrence of problems such as adhesion of the pressure-sensitive adhesive to the blade and a lack of a part of the pressure-sensitive adhesive layer.

(1) (Meth) acrylic acid ester polymer (A)
The (meth) acrylic acid ester polymer (A) contains a reactive functional group-containing monomer as a monomer unit constituting the polymer. The reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (C) to form a crosslinked structure.

  The reactive functional group-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer includes a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer) and a carboxyl in the molecule. Preferred examples include a monomer having a group (carboxyl group-containing monomer) and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer excellent in reactivity with an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent are preferable.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate in terms of reactivity with the crosslinking agent (C) of the hydroxyl group in the obtained (meth) acrylic acid ester polymer (A) and copolymerization with other monomers. Or 4-hydroxybutyl (meth) acrylate is preferable. 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. Of these, acrylic acid is preferred from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (C) of the carboxyl group and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains 5 to 30% by mass of a reactive functional group-containing monomer as a monomer unit constituting the polymer, and particularly 7 to 25% by mass. It is preferable to contain 10 to 20% by mass. When the content of the reactive functional group-containing monomer is 5% by mass or more, a crosslinking point can be secured and the structure X can be favorably formed. Moreover, desired adhesiveness is easy to be acquired as content of a reactive functional group containing monomer is 30 mass% or less.

  When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a reactive functional group-containing monomer constituting the polymer, the content is preferably 10 to 25% by mass, In particular, the content is preferably 15 to 20% by mass. Moreover, when a (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a reactive functional group-containing monomer constituting the polymer, the content thereof is 8 to 25% by mass. It is preferable that it is 10-15 mass% especially.

  The (meth) acrylic acid ester polymer (A) preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Thereby, the obtained adhesive can express preferable adhesiveness. In addition, the below-mentioned hard monomer is removed from the (meth) acrylic acid alkyl ester.

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, ( N-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate , Myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferred, and n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are particularly preferred. . These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) contains 40 to 95% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. The content is preferably 50 to 93% by mass, more preferably 55 to 90% by mass.

  Here, when high-temperature and high-humidity conditions are applied to the display body, bubbles are generated in the vicinity of the step, or outgas is generated from the plastic plate as the protective panel, causing blisters such as bubbles, floating, and peeling. Problems may occur. Based on this, the (meth) acrylic acid ester polymer (A) may contain a hard monomer having a glass transition temperature (Tg) of 70 ° C. or more as a homopolymer as a monomer unit constituting the polymer. preferable. By containing the hard monomer as a monomer unit constituting the (meth) acrylic acid ester polymer (A), the resulting pressure-sensitive adhesive has improved cohesive force and has excellent blister resistance in the display. Become. In particular, as a monomer unit constituting the (meth) acrylic acid ester polymer (A), a homopolymer having a low glass transition temperature (Tg) such as 2-ethylhexyl (meth) acrylate (for example, Tg is preferably −30) When the main component is one having a temperature of ℃ or less, particularly preferably -60 ° C or less, it is preferable to use the hard monomer because the cohesion tends to be low. The glass transition temperature (Tg) as a homopolymer of the hard monomer is preferably 75 to 200 ° C, and particularly preferably 80 to 180 ° C. In addition, when a carboxyl group-containing monomer is used as the reactive functional group-containing monomer in the (meth) acrylic acid ester polymer (A), a certain degree of cohesion can be obtained by the monomer. Therefore, in this case, the hard monomer is often not used.

  Examples of the hard monomer include methyl methacrylate (Tg 105 ° C.), isobornyl acrylate (Tg 94 ° C.), isobornyl methacrylate (Tg 180 ° C.), acryloylmorpholine (Tg 145 ° C.), adamantyl acrylate (Tg 115 ° C.), and adamantyl methacrylate. (Tg 141 ° C.), dimethylacrylamide (Tg 89 ° C.), acrylamide (Tg 165 ° C.) and the like. These may be used alone or in combination of two or more.

  Among the above hard monomers, methyl methacrylate, isobornyl acrylate and acryloyl morpholine are more preferable from the viewpoint of exerting the performance of the hard monomer while preventing adverse effects on other properties such as adhesiveness and transparency, and follow the step. From the viewpoint of further reducing the decrease in properties, isobornyl acrylate and acryloylmorpholine are particularly preferable.

  The (meth) acrylic acid ester polymer (A) preferably contains 10 to 45% by mass of the hard monomer as a monomer unit constituting the polymer, and particularly preferably contains 15 to 30% by mass. By containing the hard monomer in an amount of 10% by mass or more, an effect of improving blister resistance by the monomer unit can be expected. On the other hand, by setting the hard monomer content to 45% by mass or less, the relative shortage of other monomer units in the (meth) acrylic acid ester polymer (A) is prevented, and the pressure-sensitive adhesive obtained The adhesiveness and the step following ability can be made excellent.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group so as not to interfere with the action of the reactive functional group-containing monomer. Such other monomers include, for example, (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and aliphatic rings such as cyclohexyl (meth) acrylate (meta ) Acrylic acid ester, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid N, N-dimethylaminopropyl, etc. (meth) acrylic acid ester having acetic acid tertiary amino group, acetic acid Examples include vinyl and styrene. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 200,000 to 1,000,000, particularly preferably 300,000 to 900,000, and more preferably 400,000 to 700,000. . In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  When the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is within a relatively low range as described above, a pressure-sensitive adhesive having better step following ability can be obtained. If the weight average molecular weight of the (meth) acrylic acid ester polymer (A) exceeds 1,000,000, the step following ability may be inferior. On the other hand, when the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is less than 200,000, the pressure-sensitive adhesive may be inferior in durability.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

(2) Active energy ray-curable component (B)
When the pressure-sensitive adhesive composition P contains the bifunctional or higher active energy ray-curable component (B) in the blending amount described above, the pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition P has a step following ability. In addition to being excellent, it exhibits high film strength.

  The active energy ray-curable component (B) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays without impeding the effects of the present invention, and may be any of a monomer, an oligomer, or a polymer. Or a mixture thereof. Among them, a polyfunctional acrylate monomer having a molecular weight of less than 1000 that is excellent in compatibility with the (meth) acrylic acid ester polymer (A) and the like can be preferably exemplified.

  Examples of polyfunctional acrylate monomers having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol diene. (Meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified Di (meth) acrylate phosphate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis Bifunctional type such as [4- (2-acryloyloxyethoxy) phenyl] fluorene; trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, penta Trifunctional such as erythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, ε-caprolactone modified tris- (2- (meth) acryloxyethyl) isocyanurate Type; tetrafunctional type such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate Dipentaerythritol hexa (meth) acrylate, and hexafunctional type such as caprolactone-modified dipentaerythritol hexa (meth) acrylate. These may be used individually by 1 type and may be used in combination of 2 or more type.

  As the active energy ray-curable component (B), an active energy ray-curable acrylate oligomer can also be used. The acrylate 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, and silicone acrylate.

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

  Moreover, as the active energy ray-curable component (B), an adduct acrylate polymer in which a group having a (meth) acryloyl group is introduced into the side chain can also be used. Such an adduct acrylate-based polymer uses a copolymer of (meth) acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and a part of the crosslinkable functional group of the copolymer. , A (meth) acryloyl group and a compound having a group that reacts with a crosslinkable functional group can be reacted.

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

  The active energy ray-curable component (B) can be used by selecting one from among the above-mentioned polyfunctional acrylate monomers, acrylate oligomers and adduct acrylate polymers, or a combination of two or more. It can also be used in combination with other active energy ray-curable components.

  The content of the active energy ray-curable component (B) in the adhesive composition P is as described above. Specifically, from the viewpoint of obtaining appropriate film strength, a (meth) acrylic acid ester polymer is used. (A) It is preferable that it is 0.1 mass part or more with respect to 100 mass parts, It is preferable that it is 0.5 mass part or more especially, It is preferable that it is 1 mass part or more further. On the other hand, the gel fraction (G1) of the pressure-sensitive adhesive according to the present embodiment and the pressure-sensitive adhesive H obtained by thermally crosslinking the pressure-sensitive adhesive composition obtained by removing the active energy ray-curable component (B) from the pressure-sensitive adhesive composition P. From the viewpoint of making the gel fraction (G2) substantially the same and obtaining excellent step followability, the content of the active energy ray-curable component (B) is (meth) acrylic acid ester polymer (A) 100. It is preferably 4 parts by mass or less, more preferably 3 parts by mass or less, particularly preferably 2.5 parts by mass or less, and less than 2.0 parts by mass with respect to parts by mass. Most preferred.

(3) Crosslinking agent (C)
The pressure-sensitive adhesive composition P contains a heat-crosslinkable cross-linking agent (C), and crosslinks the (meth) acrylic acid ester polymer (A) by heating to form a three-dimensional network structure. It improves the cohesive strength of the agent and imparts durability to the pressure-sensitive adhesive.

  As said crosslinking agent (C), what is necessary is just to react with the reactive functional group which (meth) acrylic acid ester polymer (A) has, for example, isocyanate type crosslinking agent, epoxy type crosslinking agent, amine type crosslinking Agent, melamine-based crosslinking agent, aziridine-based crosslinking agent, hydrazine-based crosslinking agent, aldehyde-based crosslinking agent, oxazoline-based crosslinking agent, metal alkoxide-based crosslinking agent, metal chelate-based crosslinking agent, metal salt-based crosslinking agent, ammonium salt-based crosslinking agent Etc. Among these, when the reactive functional group of the (meth) acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that is excellent in reactivity with the hydroxyl group, and (meth) acrylic acid When the reactive functional group which the ester polymer (A) has is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group. In addition, a crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

  The content of the crosslinking agent (C) in the pressure-sensitive adhesive composition P is preferably 0.001 to 2 parts by mass, particularly 0, with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). It is preferably 0.01 to 1 part by mass, and more preferably 0.02 to 0.3 part by mass. When the content of the cross-linking agent (C) is 0.001 part by mass or more, a durability improving effect can be imparted to the obtained pressure-sensitive adhesive. When the content of the cross-linking agent (C) is 2 parts by mass or less, the degree of cross-linking can be made moderate, and the step following property of the obtained pressure-sensitive adhesive can be ensured satisfactorily.

(4) Various additives For the adhesive composition P, if desired, various additives usually used in acrylic adhesives, such as silane coupling agents, photopolymerization initiators, antistatic agents, tackifiers, Antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index adjusters, and the like can be added.

  The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule and having good compatibility with the (meth) acrylic acid ester polymer (A). Moreover, when an adhesive is an optical use, the silane coupling agent which has a light transmittance is suitable.

  Examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane Amino group-containing silicon such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane Compound, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of them, and alkyl group-containing silicon such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Examples include condensates with compounds. These may be used individually by 1 type and may be used in combination of 2 or more type.

  It is preferable that the addition amount of a silane coupling agent is 0.01-1.0 mass part with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), especially 0.05-0.5 mass. Part.

  Moreover, when using an ultraviolet-ray as an active energy ray irradiated with respect to the adhesive composition P, it is preferable that the adhesive composition P contains a photoinitiator further. By containing the photopolymerization initiator in this manner, the active energy ray-curable component (B) can be efficiently cured, and the polymerization curing time and the amount of active energy ray irradiation can be reduced.

  Examples of such a photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2- Phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) Phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-di Tylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2 4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

  The photopolymerization initiator is preferably used in an amount in the range of 2 to 15 parts by mass, particularly 4 to 12 parts by mass with respect to 100 parts by mass of the active energy ray-curable component (B).

(5) Manufacture of adhesive composition The adhesive composition P manufactured the (meth) acrylic acid ester polymer (A), the obtained (meth) acrylic acid ester polymer (A), and an active energy ray. While mixing a sclerosing | hardenable component (B) and a crosslinking agent (C), it can manufacture by adding an additive if desired.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 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] and the like.

  Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  Once the (meth) acrylic acid ester polymer (A) is obtained, the solution of the (meth) acrylic acid ester polymer (A) is added to the active energy ray-curable component (B), the crosslinking agent (C), and, if desired. An adhesive composition P is obtained by adding an additive and mixing well.

(6) Manufacture of pressure-sensitive adhesive After applying the above pressure-sensitive adhesive composition P to a desired object, the composition is thermally crosslinked and cured by irradiation with active energy rays (active energy ray curing). Is obtained.

  Thermal crosslinking of the adhesive composition P can be performed by heat treatment. This heat treatment can also serve as a drying treatment after the application of the adhesive composition P. The heating temperature of the heat treatment is preferably 50 to 150 ° C, and particularly preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

  Here, active energy rays refer to those having energy quanta among electromagnetic waves or charged particle beams, and specific examples include ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays that are easy to handle are particularly preferable.

Irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW / cm ^{2 in} illuminance. Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 200~2000mJ / cm ^2. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation amount is preferably about 10 to 1000 krad.

  When the pressure-sensitive adhesive composition P is heat-treated, the (meth) acrylic acid ester polymer (A) reacts with the crosslinking agent (C) to form a crosslinked structure, that is, a three-dimensional network structure. Moreover, when an active energy ray is irradiated with respect to the adhesive composition P, an active energy ray hardening component (B) will superpose | polymerize and it will harden | cure while being entangled in the said three-dimensional network structure. The pressure-sensitive adhesive according to this embodiment obtained in this manner is excellent in step following ability and exhibits high film strength.

  In addition, in manufacturing the adhesive which concerns on this embodiment, after performing heat processing, you may perform active energy ray irradiation and you may perform both processes simultaneously. Moreover, it is also preferable to provide a curing period of about 1 to 2 weeks at normal temperature (for example, 23 ° C., 50% RH) after heat treatment or irradiation with active energy rays.

(7) Gel fraction The gel fraction (G1) of the pressure-sensitive adhesive according to this embodiment is preferably 40 to 80%, particularly preferably 45 to 70%, and more preferably 50 to 65%. Preferably there is. When the gel fraction (G1) is 40% or more, the coating strength of the pressure-sensitive adhesive can be ensured satisfactorily. Further, when the gel fraction (G1) is 80% or less, the step following performance of the pressure-sensitive adhesive can be ensured satisfactorily.

(8) Elongation at break The pressure-sensitive adhesive according to this embodiment is a pressure-sensitive adhesive layer having a thickness of 600 μm and a width of 10 mm. The elongation at break when stretched at is preferably 1000% or more, particularly preferably 1100 to 4000%, and more preferably 1200 to 2500%. In addition, the specific method of this tensile test is as showing to the test example mentioned later.

  The pressure-sensitive adhesive according to the present embodiment can achieve the above-described elongation at break by forming the above-described pressure-sensitive adhesive composition P by thermal crosslinking and active energy ray curing. When the elongation at break is large as described above, the pressure-sensitive adhesive is more excellent in step following ability.

(9) Step-following rate The pressure-sensitive adhesive according to this embodiment preferably has a step-following rate (%) represented by the following formula of 20% or more, particularly preferably 25 to 80%. Is preferably 30 to 70%.
Step follow-up rate (%) = {(height (μm) of the step maintained without gaps or bubbles after a predetermined durability test) / (thickness of the adhesive layer)} × 100
In addition, the test method of a level | step difference tracking rate is as showing to the test example mentioned later.

  The pressure-sensitive adhesive according to the present embodiment can achieve a large step following rate as described above by thermal crosslinking and active energy ray curing of the above-described pressure-sensitive adhesive composition P.

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to this embodiment includes two release sheets 12a and 12b and the two release sheets 12a so as to be in contact with the release surfaces of the two release sheets 12a and 12b. , 12b and an adhesive layer 11 sandwiched between the two layers. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

(1) Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 is composed of the above-described pressure-sensitive adhesive, that is, a pressure-sensitive adhesive formed by thermal crosslinking and active energy ray curing of the pressure-sensitive adhesive composition P.

  The thickness of the pressure-sensitive adhesive layer 11 (value measured according to JIS K7130) is preferably 10 to 1000 μm, more preferably 30 to 400 μm, and particularly preferably 50 to 300 μm. The pressure-sensitive adhesive layer 11 may be formed as a single layer or may be formed by laminating a plurality of layers.

  If the thickness of the pressure-sensitive adhesive layer 11 is less than 10 μm, sufficient step followability may not be obtained. On the other hand, workability will become favorable in the thickness of the adhesive layer 11 being 1000 micrometers or less.

(2) Release sheet Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate. Phthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film A polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 11) of the release sheets 12a and 12b is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. Of the release sheets 12a and 12b, one release sheet is preferably a heavy release release sheet having a high release force, and the other release sheet is preferably a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of release sheet 12a, 12b, Usually, it is about 20-150 micrometers.

(3) Manufacture of an adhesive sheet As one manufacture example of the adhesive sheet 1, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of one peeling sheet 12a (or 12b). Then, the adhesive layer P is formed by performing heat treatment on the coating layer to thermally crosslink the adhesive composition P and irradiating active energy rays to cure the adhesive composition P. The release surface of the other release sheet 12b (or 12a) is superimposed on the pressure-sensitive adhesive layer 11 formed as described above, and this is used as the pressure-sensitive adhesive sheet 1. In addition, you may perform irradiation of the said active energy ray after carrying out the thermal bridge | crosslinking of the coating layer of the adhesive composition P, and overlapping the peeling surface of the other peeling sheet 12b (or 12a) on the said coating layer.

  As another production example of the pressure-sensitive adhesive sheet 1, the pressure-sensitive adhesive composition P is prepared by applying a coating liquid of the pressure-sensitive adhesive composition P to the release surface of one release sheet 12 a and subjecting the coating layer to heat treatment. Are thermally crosslinked and irradiated with active energy rays to cure the pressure-sensitive adhesive composition P to form a first pressure-sensitive adhesive layer. In addition, the adhesive liquid P is applied to the release surface of the other release sheet 12b, and the adhesive layer P is thermally cross-linked by applying heat treatment to the coating layer. Is applied to cure the pressure-sensitive adhesive composition P to form a second pressure-sensitive adhesive layer. And the peeling sheet 12a with the 1st adhesive layer and the peeling sheet 12b with the 2nd adhesive layer are bonded together so that both adhesive layers may mutually contact, and let this be the adhesive sheet 1. FIG. Instead of obtaining the pressure-sensitive adhesive sheet 1 after forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer individually, the respective application layers are brought into contact with each other at the stage of thermal crosslinking, and then summarized. The adhesive sheet 1 may be obtained by irradiating active energy rays.

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P. The heat treatment conditions for the applied adhesive composition P are as described above.

  In the above pressure-sensitive adhesive sheet 1, since the pressure-sensitive adhesive layer 11 is excellent in level-step following property, even when the pressure-sensitive adhesive layer 11 is applied to a display member having a level difference and then exposed to predetermined durability conditions, the level difference and the pressure-sensitive adhesive layer 11 are present. It is difficult for voids or bubbles to be formed between them, and the pressure-sensitive adhesive layer 11 can fill the steps. Further, since the pressure-sensitive adhesive layer 11 has high film strength, for example, when the pressure-sensitive adhesive sheet 1 is punched, there is a problem that the pressure-sensitive adhesive adheres to the blade and a part of the pressure-sensitive adhesive layer 11 is lost. Is suppressed.

(4) Haze value The pressure-sensitive adhesive layer 11 in the present embodiment preferably has a haze value (measured according to JIS K7136: 2000) of 3% or less, particularly preferably 2% or less. Further, it is preferably 1% or less. When the haze value is 3% or less, the transparency is very high, which is suitable for optical applications.

(5) Adhesive strength The adhesive sheet 1 in the present embodiment has an adhesive strength (measured according to JIS Z0237: 2009) of 5 N / 25 mm or more in order to exhibit excellent step following ability even after durability conditions. It is preferably 10N / 25mm or more, particularly preferably 25N / 25mm or more. Moreover, from the viewpoint of imparting reworkability to the pressure-sensitive adhesive sheet 1, the pressure-sensitive adhesive force is preferably 50 N / 25 mm or less, more preferably 40 N / 25 mm or less, and particularly preferably 35 N / 25 mm or less. . The details of the adhesive strength test method are as described in the test examples.

[Display]
As shown in FIG. 2, the display body 2 according to this embodiment includes a first display body constituent member 21 (one display body constituent member) having a step on at least a surface to be bonded, and a second display body. The display body constituent member 22 (other display body constituent member) and the pressure-sensitive adhesive layer 11 that is located between them and bonds the first display body constituent member 21 and the second display body constituent member 22 to each other. It is prepared for. In the display body 2 according to the present embodiment, the first display body constituting member 21 has a step on the surface on the pressure-sensitive adhesive layer 11 side, and specifically has a step due to the printing layer 3. .

  Examples of the display body 2 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel.

  It is preferable that the 1st display body structural member 21 is a protective plate which consists of a laminated body containing them other than a glass plate, a plastic plate, etc. In this case, the printing layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side in the first display member constituting member 21.

  The second display member constituting member 22 includes a display module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, etc.) or a part thereof (for example, a polarizing plate). An optical member) is preferable.

  The glass plate is not particularly limited. For example, chemically tempered glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate Glass etc. are mentioned. Although the thickness of a glass plate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

  The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. Although the thickness of a plastic board is not specifically limited, Usually, it is 0.2-5 mm, Preferably it is 0.4-3 mm.

  Various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) may be provided on one or both surfaces of the glass plate or plastic plate, or an optical member. May be laminated. Moreover, the transparent conductive film and the metal layer may be patterned.

  Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation plate (retarding film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, and a hard coat film. And a semi-transmissive reflective film.

  The material which comprises the printing layer 3 is not specifically limited, The well-known material for printing is used. The thickness of the printing layer 3, that is, the height of the step, is preferably 3 to 45 μm, particularly preferably 5 to 35 μm, more preferably 7 to 25 μm, and 7 to 15 μm. Is most preferred.

  In order to manufacture the display body 2, as an example, first, the adhesive sheet 1 is cut into a size corresponding to the first display body constituting member 21 and the second display body constituting member 22. In the cutting, the entire thickness direction of the pressure-sensitive adhesive sheet 1 may be cut, or the other release sheet 12b of the pressure-sensitive adhesive sheet 1 may not be cut, and the pressure-sensitive adhesive layer 11 and the one release sheet 12a may be half-cut. . At this time, since the coating strength of the pressure-sensitive adhesive layer 11 is high, it is suppressed that the pressure-sensitive adhesive adheres to the blade and a part of the pressure-sensitive adhesive layer 11 is lost.

  Next, one release sheet 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1 is bonded to the surface of the first display member constituting member 21 on the side where the printed layer 3 exists. . Then, the other peeling sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1 and the second display member constituting member 22 are bonded together.

  When the pressure-sensitive adhesive layer 11 and the first display member constituting member 21 are bonded together in the above process, the pressure-sensitive adhesive layer 11 is excellent in level-step following capability, so that the level difference between the printed layer 3 and the pressure-sensitive adhesive layer even after a predetermined durability condition. It is difficult to form a gap between the pressure-sensitive adhesive layer 11 and the pressure-sensitive adhesive layer 11 can fill the step.

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

  For example, one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted. Further, the first display member constituting member 21 may have a step other than the printing layer 3 or may not have a step. Furthermore, not only the 1st display body structural member 21, but the 2nd display body structural member 22 may also have a level | step difference in the adhesive layer 11 side.

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

[Example 1]
1. Preparation of (meth) acrylic acid ester polymer 90 parts by weight of n-butyl acrylate and 10 parts by weight of acrylic acid were copolymerized to prepare a (meth) acrylic acid ester polymer (A). When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, it was a weight average molecular weight (Mw) of 400,000.

2. Preparation of adhesive composition As (meth) acrylic acid ester polymer (A) 100 mass parts (solid content conversion value; same hereafter) obtained by the said process (1), and active energy ray hardening component (B) Tris (acryloxyethyl) isocyanurate (product name “M-315” manufactured by Toa Gosei Co., Ltd.) and 1,3-bis (N, N—) as an epoxy-based crosslinking agent (C) Diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name “TETRAD-C”, solid content concentration: 100% by mass) and 0.05 part by mass of 3-glycidoxypropyltrimethoxy as a silane coupling agent Silane (manufactured by Shin-Etsu Chemical Co., Ltd., product name “KBM-403”) is mixed with 0.2 part by mass, and 1-hydroxycyclohexyl phenyl ketone (BASF) is used as a photopolymerization initiator. The product name “Irgacure 184” manufactured by the company is added at a mass equivalent to 10% by mass of the component (B), sufficiently stirred, and diluted with methyl ethyl ketone to give an adhesive composition having a solid content concentration of 37% by mass. A coating solution of the product was obtained.

Here, Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic acid ester polymer]
BA: n-butyl acrylate AA: acrylic acid 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate IBXA: isobornyl acrylate ACMO: acryloylmorpholine VAc: vinyl acetate [active energy ray curable component]
M-315: Tris (acryloxyethyl) isocyanurate (manufactured by Toa Gosei Co., Ltd., product name “M-315”)
A-400: Polyethylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “A-400”, molecular weight of polyethylene glycol: 400)
A-TMM-3: Pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “A-TMM-3”)
A-DPH: Dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “A-DPH”)
[Crosslinking agent]
Epoxy-1: 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane (product name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Company)
Epoxy-2: N, N, N ′, N′-tetraglycidyl-m-xylenediamine (manufactured by Mitsubishi Gas Chemical Company, product name “TETRAD-X”)
Isocyanate: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name “L-45”)

3. Production of pressure-sensitive adhesive sheet Peeling of a heavy-peelable release sheet (product name "SP-PET752150", manufactured by Lintec Corporation), in which one side of a polyethylene terephthalate film was subjected to a release treatment with a silicone-based release agent The treated surface was applied with a knife coater. And after heat-processing with respect to a coating layer for 2 minutes at 100 degreeC, the ultraviolet-ray was irradiated on the following conditions, and the 25-micrometer-thick adhesive layer was formed.
[UV irradiation conditions]
・ Light source: High-pressure mercury lamp ・ Light quantity: 500 mJ / cm ²
Illuminance: 200 mW / cm ²
The illuminance and the light amount were confirmed by a UV illuminance / light meter “UVPF-36” manufactured by Eye Graphics.

  Similarly, a release treatment of a light release release sheet (product name “SP-PET382120” manufactured by Lintec Corporation) in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent was applied to the obtained adhesive composition coating solution. The surface was coated with a knife coater. And after heat-processing with respect to an application layer for 2 minutes at 100 degreeC, it irradiated with the ultraviolet-ray similarly to the above, and formed the 25-micrometer-thick 2nd adhesive layer.

  Next, both the pressure-sensitive adhesive release sheet with the first pressure-sensitive adhesive layer obtained above and the light release-type release sheet with the second pressure-sensitive adhesive layer obtained above are in contact with each other. Thus, a pressure-sensitive adhesive sheet having a configuration of heavy release type release sheet / pressure-sensitive adhesive layer (thickness: 50 μm) / light release type release sheet was produced. The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

[Examples 2 to 17, Comparative Examples 1 to 4]
The ratio of each monomer constituting the (meth) acrylic acid ester polymer (A), the weight average molecular weight of the (meth) acrylic acid ester polymer (A), the type and blending amount of the active energy ray-curable component (B), A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the type and amount of the crosslinking agent (C) and the amount of the silane coupling agent were changed as shown in Table 1. In Comparative Examples 1 and 4, the ultraviolet irradiation treatment was not performed.

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

[Test Example 1] (Measurement of adhesive strength)
The light release type release sheet was peeled off from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was easily made of a polyethylene terephthalate film (PET A4300, manufactured by Toyobo Co., Ltd., thickness: 100 μm) having an easy adhesion layer. Bonded to the adhesive layer. The laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample. The heavy release release sheet was peeled off from the sample, and the exposed adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.).

  Then, after leaving for 24 hours under the conditions of normal pressure, 23 ° C. and 50% RH, using a tensile tester (Orientec, product name “Tensilon”) according to JIS Z0237: 2009, the peeling rate. The adhesive strength (N / 25 mm) was measured under the conditions of 300 mm / min and peeling angle of 180 °. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)
About the adhesive layer of the adhesive sheet obtained by the Example and the comparative example, according to JISK7361-1: 1997, a haze value was used using a haze meter (Nippon Denshoku Industries Co., Ltd., product name "NDH-2000"). (%) Was measured. The results are shown in Table 2.

[Test Example 3] (Measurement of gel fraction)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), the mass was weighed with a precision balance, and the mesh By subtracting the single mass, the mass of the adhesive alone was calculated. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the pressure sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (G1;%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 4] (Measurement of gel fraction change rate)
In Examples and Comparative Examples, adhesive compositions were prepared in the same manner as described above except that the active energy ray-curable component (B) was not added. A pressure-sensitive adhesive sheet was prepared in the same manner as described above except that the pressure-sensitive adhesive composition was used and no ultraviolet irradiation treatment was performed. About the adhesive layer of the obtained adhesive sheet, it carried out similarly to Test Example 3, and measured the gel fraction (G2;%). When the gel fraction was G2, and the gel fraction measured in Test Example 3 was G1, the gel fraction change rate (%) represented by the following formula was calculated. The results are shown in Table 2.
Gel fraction change rate (%) = {(G1-G2) / G2} × 100

[Test Example 5] (Tensile test)
After laminating a plurality of pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples so as to have a total thickness of 600 μm, a 10 mm wide × 75 mm long sample was cut out. The sample is set in a tensile tester (product name “Tensilon”, manufactured by Orientec Co., Ltd.) so that the sample measurement site is 10 mm wide × 20 mm long (extension direction), and the measurement is performed in an environment of 23 ° C. and 50% RH. The sample was stretched at a tensile speed of 200 mm / min using a tensile tester, and the elongation at break (%) was measured. Moreover, the sample was extended to the breaking elongation and the maximum stress (N) was measured. The results are shown in Table 2.

[Test Example 6] (Blister resistance evaluation)
Polyethylene terephthalate film (manufactured by Oike Kogyo Co., Ltd., ITO film, thickness) provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples 125 μm) transparent conductive film and polycarbonate (PC) board (Mitsubishi Gas Chemical Co., Ltd., product name “Iupilon sheet MR58”, thickness: 1 mm) or acrylic sheet made of polymethyl methacrylate (PMMA) (Mitsubishi Gas Chemical Co., Ltd.) And a product name “Iupilon sheet MR200” (thickness: 1 mm).

The obtained laminate was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and then allowed to stand at normal pressure, 23 ° C. and 50% RH for 15 hours. Subsequently, it was stored for 72 hours under 85 ° C. and 85% RH durability conditions. Thereafter, it was visually confirmed whether or not the pressure-sensitive adhesive layer had bubbles, floating or peeling, and blister resistance was evaluated according to the following criteria. The results are shown in Table 2.
A: There were no bubbles, no floating, and no peeling.
○: Only bubbles with a diameter of 0.1 mm or less were generated.
X: Bubbles with a diameter of more than 0.1 mm, floating or peeling occurred.

[Test Example 7] (Evaluation of film strength)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in the examples and comparative examples were laminated in a plurality of layers so that the total thickness was 1 mm, and the laminate was cut into a cutting device (product name “Super Cutter PN1- 600 "). The cut surface (length: 100 mm) of the pressure-sensitive adhesive layer after cutting was visually confirmed, and the coating strength was evaluated according to the following criteria. The results are shown in Table 2.
○: No chipping of the adhesive layer on the cut surface (high film strength)
×: There is a lack of the adhesive layer on the cut surface (low film strength)

[Test Example 8] (Evaluation of step following ability)
On the surface of a glass plate (manufactured by NSG Precision, product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), UV curable ink (product name “POS-911 Black”, manufactured by Teikoku Ink Co., Ltd.) ) Was screen-printed in a frame shape (outer shape: 90 mm long × 50 mm wide, 5 mm wide) so that the coating thickness was any one of 5 μm, 10 μm, 15 μm and 20 μm. Next, irradiation with ultraviolet rays (80 W / cm ² , ^two metal halide lamps, lamp height of 15 cm, belt speed of 10 to 15 m / min) is performed to cure the printed ultraviolet curable ink, and a level difference due to printing (level difference) A stepped glass plate having a thickness of any one of 5 μm, 10 μm, 15 μm, and 20 μm was produced.

  The light release type release sheet was peeled off from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was replaced with a polyethylene terephthalate film having an easy adhesion layer (product name “PET A4300” manufactured by Toyobo Co., Ltd., thickness: 100 μm) easy adhesion layer. Next, the heavy release type release sheet was peeled off to expose the pressure-sensitive adhesive layer. Then, using a laminator (product name “LPD3214”, manufactured by Fuji Plastics Co., Ltd.), the laminate is laminated on each stepped glass plate so that the adhesive layer covers the entire frame-like print, and this is used as an evaluation sample. did.

The obtained sample for evaluation was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and then allowed to stand at normal pressure, 23 ° C. and 50% RH for 24 hours. Subsequently, it was stored for 72 hours under an endurance condition of 85 ° C. and 85% RH (endurance test), and then the step following ability was evaluated. Step followability is determined by whether or not the printing step is completely filled with the adhesive layer.If gaps or bubbles are observed at the interface between the printing step and the adhesive layer, it can follow the printing step. It is judged that there was not. Here, the step following property was evaluated as a step following rate (%) represented by the following formula. The results are shown in Table 2.
Step follow-up rate (%) = {(height of the step maintained without gaps or bubbles after the durability test (μm)) / (thickness of the adhesive layer: 50 μm)} × 100

  As can be seen from Table 2, the pressure-sensitive adhesive layers obtained in the examples were excellent in step following ability and high in film strength.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding between a display module and a protective plate having a step.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet 2 ... Display body 21 ... 1st display body structural member 22 ... 2nd display body structural member 3 ... Print layer

Claims (11)

A pressure-sensitive adhesive for bonding at least one display member constituting member having a step on the surface to be bonded and another display member constituting member, and the one display member constituting member and the other A pressure-sensitive adhesive before contacting the display member constituting member,
The adhesive is
(Meth) acrylic acid ester polymer (A) containing a reactive functional group-containing monomer as a monomer unit constituting the polymer;
A bifunctional or higher active energy ray-curable component (B);
By using an adhesive composition containing a thermally crosslinkable crosslinking agent (C),
The (meth) acrylic acid ester polymer (A) contains a component crosslinked by the crosslinking agent (C) and a component obtained by polymerizing the active energy ray-curable component (B);
Content of the said active energy ray hardening component (B) in the said adhesive composition is 0.1 mass part or more and 4 mass with respect to 100 mass parts of said (meth) acrylic acid ester polymers (A). When the pressure-sensitive adhesive layer has a thickness of 600 μm and a width of 10 mm, the film is stretched to the breaking elongation at a measurement length of 20 mm and a tensile speed of 200 mm / min in an environment of 23 ° C. and 50% RH. A pressure-sensitive adhesive having a maximum stress of 2.8 N or more (provided that the content of the ethylenically unsaturated compound containing one ethylenically unsaturated group is 5 to 70 wt. % Excluding those that are%) .   The pressure-sensitive adhesive according to claim 1, wherein the gel fraction (G1) is 40 to 80%.   When the adhesive layer has a thickness of 600 μm and a width of 10 mm, the elongation at break when stretched at a measurement length of 20 mm and a tensile speed of 200 mm / min in an environment of 23 ° C. and 50% RH is 1000% or more. The pressure-sensitive adhesive according to claim 1 or 2.   The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the (meth) acrylic acid ester polymer (A) has a weight average molecular weight of 200,000 to 1,000,000.   The said (meth) acrylic acid ester polymer (A) contains 5-30 mass% of said reactive functional group containing monomers as a monomer unit which comprises the said polymer, Any one of Claims 1-4 characterized by the above-mentioned. The pressure-sensitive adhesive according to claim 1. The reactive functional group of the reactive functional group-containing monomer is a carboxyl group and / or a hydroxyl group;
The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the crosslinking agent (C) is an isocyanate crosslinking agent and / or an epoxy crosslinking agent.   The adhesive sheet which has an adhesive layer which consists of an adhesive as described in any one of Claims 1-6.   The pressure-sensitive adhesive sheet according to claim 7, wherein the pressure-sensitive adhesive layer has a thickness of 10 to 400 μm. The pressure-sensitive adhesive sheet includes two release sheets,
The pressure-sensitive adhesive sheet according to claim 7 or 8, wherein the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. At least one display member constituting member having a step on the surface to be bonded;
A method for producing a display body comprising other display body constituent members,
The said display body structural member and said other display body structural member are mutually bonded using the adhesive layer of the adhesive sheet as described in any one of Claims 7-9. Body manufacturing method.   The method of manufacturing a display body according to claim 10, wherein the step has a frame shape in a plan view.

Images