WO2015145633A1 - Adhesive composition, adhesive agent, and adhesive sheet - Google Patents

Abstract

An adhesive composition which comprises an active-energy-ray-curable adhesive component and light-diffusing microparticles, wherein the difference between the refractive index of the active-energy-ray-curable adhesive component and the refractive index of the light-diffusing microparticles is 0.005 to 0.2, and the average particle diameter of the light-diffusing microparticles is 0.8 to 2.9 μm as determined by a centrifugal sedimentation photo-extinction method. When an adhesive agent produced from the adhesive composition is used, an optical member which has sufficient durability and a sufficient light-diffusing property and is highly precise can be provided.

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive (a material obtained by curing a pressure-sensitive adhesive composition), and a pressure-sensitive adhesive sheet, and in particular, a pressure-sensitive adhesive composition suitable for optical members such as polarizing plates, a pressure-sensitive adhesive, and The present invention relates to an adhesive sheet.

Generally, in a liquid crystal panel, a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition is often used to adhere a polarizing plate or a retardation plate to a glass substrate of a liquid crystal cell. However, since optical members such as polarizing plates and retardation plates tend to shrink due to heat, etc., shrinkage occurs due to thermal history, and as a result, stress remains in the adhesive layer laminated on the optical member. There has been pointed out a problem of durability such as peeling at the interface (so-called floating or peeling).

On the other hand, the liquid crystal panel has an advantage that it is thin and consumes less power, but has a problem that it is insufficient in terms of luminance and viewing angle. From the viewpoint of improving this problem with the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer used for the optical member may be required to have light diffusibility.

In order to impart light diffusibility to the pressure-sensitive adhesive layer, fine particles are usually added to the pressure-sensitive adhesive layer. However, when fine particles are added to the pressure-sensitive adhesive layer, due to differences in thermal expansibility or heat-shrinkability between the fine particles and the pressure-sensitive adhesive, misalignment occurs at the interface between the fine particles and the pressure-sensitive adhesive due to thermal history, generating bubbles. Such a problem is concerned.

In addition, as described above, in the case of an optical member that is thermally contracted, the pressure-sensitive adhesive layer is also deformed accordingly, and there is a concern that a problem arises in that a gap occurs at the interface between the foreign particles and the pressure-sensitive adhesive, and bubbles are generated. The In fact, when the pressure-sensitive adhesive layer to which fine particles are added is used for an optical member, the floating and peeling due to the heat history are worsened and the durability tends to be lower than when no fine particles are added.

On the other hand, in patent document 1 and patent document 2, by applying an adhesive having a high storage elastic modulus as the light diffusive adhesive, the thermal contraction of the optical member itself is suppressed by the adhesive layer, and at the same time, the thermal history. Attempts were also made to prevent the occurrence of misalignment at the interface between the adhesive and the fine particles due to deformation. And the generation | occurrence | production of the float and peeling by a heat history which was a problem of the light diffusable adhesive in an optical member was solved brilliantly.

JP 2007-332341 A JP 2008-260813 A

Incidentally, in recent years, with the development of various mobile electronic devices such as smartphones and tablet terminals, high-definition image display has been demanded. In order to contribute to high-definition image display in response to such demands, the pressure-sensitive adhesive for optical members can provide a high-definition optical member while having sufficient light diffusibility. The need for is increasing.

The present invention has been made in view of such a situation, and a pressure-sensitive adhesive composition capable of obtaining a high-definition optical member while having sufficient durability and light diffusibility as a light-diffusing pressure-sensitive adhesive. It aims at providing an adhesive and an adhesive sheet.

In order to achieve the above object, first, the present invention includes an active energy ray-curable adhesive component and light diffusing fine particles, and the refractive index of the active energy ray curable adhesive component and the light diffusing fine particles The pressure-sensitive adhesive composition is characterized in that a difference in refractive index is 0.005 to 0.2, and an average particle diameter of the light diffusing fine particles by a centrifugal sedimentation light transmission method is 0.8 to 2.9 μm. (Invention 1).

In the above invention (Invention 1), sufficient durability and light diffusibility are exhibited by containing an active energy ray-curable adhesive component and light diffusing fine particles. Moreover, by defining the difference between the refractive index of the active energy ray-curable adhesive component and the refractive index of the light diffusing fine particles and the average particle diameter of the light diffusing fine particles as described above, An optical member is obtained.

In the invention (Invention 1), the active energy ray-curable adhesive component preferably contains a (meth) acrylic acid ester polymer and an active energy ray-curable compound (Invention 2).

In the above invention (Invention 2), the active energy ray-curable compound is preferably a polyfunctional acrylate monomer having a molecular weight of 1000 or less (Invention 3).

In the said invention (invention 2 and 3), the said active energy ray hardening adhesive component contains a crosslinking agent further, The said (meth) acrylic acid ester polymer is the said bridge | crosslinking as a monomer unit which comprises the said polymer. It is preferable to contain a monomer having a functional group that reacts with the agent (Invention 4).

In the above inventions (Inventions 1 to 4), the light diffusing fine particles are preferably fine particles made of a silicon-containing compound having an intermediate structure between inorganic and organic (Invention 5).

Secondly, the present invention provides an adhesive obtained by curing the above-mentioned adhesive composition (Invention 1 to 5) (Invention 6).

In the above invention (Invention 6), the haze value is preferably 10 to 80% (Invention 7).

Thirdly, the present invention provides a pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive (Inventions 6 and 7). (Invention 8).

Fourthly, the present invention includes two release sheets and an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, and the adhesive layer is the adhesive ( An adhesive sheet comprising Inventions 6 and 7) is provided (Invention 9).

According to the pressure-sensitive adhesive composition, pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present invention, a high-definition optical member can be obtained while having sufficient durability and light diffusibility.

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

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to this embodiment (hereinafter referred to as “pressure-sensitive adhesive composition P”) contains an active energy ray-curable pressure-sensitive adhesive component and light diffusing fine particles. The difference between the refractive index of the active energy ray-curable adhesive component and the refractive index of the light diffusing fine particles is 0.005 to 0.2, and the average particle size of the light diffusing fine particles by the centrifugal sedimentation light transmission method is 0. .8 to 2.9 μm. In an optical member provided with a pressure-sensitive adhesive layer obtained by curing such a pressure-sensitive adhesive composition P, particularly in a polarizing plate, it has excellent light diffusibility and high glare suppression while having sufficient durability. It can be fine.

1. Active energy ray-curable adhesive component The adhesive composition P contains an active energy ray-curable adhesive component. The “active energy ray-curable adhesive component” in the present specification refers to a component that is cured by irradiation with an active energy ray and exhibits adhesiveness, and may consist of a single component or a plurality of components (compositions). ). In the case of the latter, the component hardened | cured by irradiation of an active energy ray and the component which does not harden | cure by irradiation of an active energy ray and shows adhesiveness may be contained.

As described above, the pressure-sensitive adhesive containing light diffusing fine particles often causes a problem in durability when applied to an optical member such as a polarizing plate. However, the pressure-sensitive adhesive composition P containing the active energy ray-curable pressure-sensitive adhesive component is excellent in durability. In addition, the pressure-sensitive adhesive containing light diffusing fine particles generally has a reduced cohesive force, and when the release sheet is peeled from the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer may be taken on the release sheet side. The pressure-sensitive adhesive composition P containing the energy ray-curable pressure-sensitive adhesive component is less likely to cause the above-described problems when cured, and the resulting pressure-sensitive adhesive layer has excellent handling properties.

As the active energy ray-curable adhesive component, those containing a (meth) acrylic acid ester polymer and an active energy ray-curable compound are preferable. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”. Hereinafter, the active energy ray-curable adhesive component containing the (meth) acrylic acid ester polymer and the active energy ray-curable compound will be mainly described.

(1) (Meth) acrylic acid ester polymer (Meth) acrylic acid ester polymer (hereinafter sometimes referred to as “(meth) acrylic acid ester polymer (A)”) is a monomer constituting the polymer. The alkyl group preferably contains (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms. Thereby, the obtained adhesive can express preferable adhesiveness. The (meth) acrylic acid ester polymer (A) includes a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms and a monomer having a reactive functional group (reactive functional group-containing monomer). And a copolymer with other monomer used as desired. By including a reactive functional group-containing monomer as a monomer constituting the polymer (meth) acrylic acid ester polymer (A), it is possible to improve adhesion with a glass surface such as a liquid crystal cell, Moreover, it can react with a crosslinking agent (C) described later to form a crosslinked structure.

Examples of (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n- (meth) acrylate. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples thereof include n-dodecyl, 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 an alkyl group having 1 to 8 carbon atoms are preferred, and n-butyl (meth) acrylate is particularly preferred. In addition, these may be used independently and may be used in combination of 2 or more type.

The (meth) acrylic acid ester polymer (A) contains 50 to 99% 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 65 to 97% by mass, more preferably 80 to 95% by mass.

As the reactive functional group-containing monomer, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing) Monomer) and the like. One of these reactive functional group-containing monomers may be used alone, or two or more thereof may be used in combination.

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 is preferred from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (C) of the hydroxyl group and the copolymerizability with other monomers. Is 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. 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 1 to 25% by mass, particularly 2 to 15% by mass of a reactive functional group-containing monomer as a monomer unit constituting the polymer. The content is preferably 3 to 10% by mass.

Examples of the other monomer include aliphatic rings such as (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and cyclohexyl (meth) acrylate (meth) Non-crosslinkable acrylamide such as acrylic ester, acrylamide, methacrylamide, etc. Non-crosslinkable tertiary such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Examples thereof include (meth) acrylic acid ester having an amino group, vinyl acetate, 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. In addition, since a (meth) acrylic acid ester polymer (A) is a component which provides adhesiveness, it is preferable not to have active energy ray curability.

The (meth) acrylic acid ester polymer (A) preferably has a weight average molecular weight of 400,000 to 2,500,000, particularly preferably 1,000,000 to 2,200,000, and more preferably 1,400,000 to 2,000,000. preferable. By making the weight average molecular weight of the (meth) acrylic acid ester polymer (A) relatively high, durability can be further improved. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

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

(2) Active energy ray-curable compound The active energy ray-curable compound contained in the active energy ray-curable adhesive component in the present embodiment (hereinafter may be referred to as “active energy ray-curable compound (B)”). As long as the difference in refractive index between the active energy ray-curable adhesive component containing the active energy ray-curable compound (B) and the light diffusing fine particles falls within the above-described range, it may be any of a monomer, an oligomer, or a polymer. It may be a mixture thereof. Among them, a polyfunctional acrylate monomer having a molecular weight of 1000 or less that is excellent in compatibility with the (meth) acrylic acid ester polymer (A) and the like can be preferably exemplified.

In the adhesive composition P in the present embodiment, the active energy ray-curable compound (B) forms a chemical bond with each other by irradiation with active energy rays to generate a three-dimensional network structure. Then, by capturing the (meth) acrylic acid ester polymer (A) in the structure, the cohesive force is improved, and as a result, the durability is excellent.

Examples of polyfunctional acrylate monomers having a molecular weight of 1000 or less 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 Bifunctional type such as di (meth) acrylate phosphate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, etc .; trimethylolpropane tri (meth) acrylate Rate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanate Trifunctional type such as nurate and ε-caprolactone modified tris- (2- (meth) acryloxyethyl) isocyanurate; tetrafunctional type such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; propionic acid modified 5-functional type such as dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate And hexafunctional types such as cartons. These may be used individually by 1 type and may be used in combination of 2 or more type.

The content of the active energy ray-curable compound (B) is preferably 1 to 50 parts by mass, particularly 5 to 30 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). It is preferable that the amount is 10 to 20 parts by mass. When the content of the active energy ray-curable compound (B) is within the above range, the resulting pressure-sensitive adhesive is superior in durability, and the resulting pressure-sensitive adhesive layer has excellent handling properties. Become. Furthermore, the adhesiveness by the (meth) acrylic acid ester polymer (A) is maintained well.

(3) Crosslinking agent It is also preferable that the adhesive composition P contains a crosslinking agent (C) as an active energy ray-curable adhesive component. When the adhesive component of the adhesive composition P contains a (meth) acrylic acid ester polymer (A) containing a reactive functional group-containing monomer as a monomer unit constituting the polymer, and a crosslinking agent (C), When the adhesive composition P is heated, the crosslinking agent (C) reacts with the reactive functional group of the reactive functional group-containing monomer constituting the (meth) acrylic acid ester polymer (A). Thereby, the structure by which (meth) acrylic acid ester polymer (A) was bridge | crosslinked with the crosslinking agent (C) is formed, and the cohesion force of the adhesive which is obtained improves.

In addition, in the adhesive composition P in this embodiment, the above-mentioned active energy ray-curable compound (B) improves the cohesive force of the obtained adhesive to improve durability. However, it is more preferable to use the crosslinking agent (C) in combination from the viewpoint of further improving the cohesive force while maintaining the appropriate adhesive strength of the adhesive and further improving the durability.

The crosslinking agent (C) may be any one that reacts with the reactive functional group of the (meth) acrylic acid ester polymer (A). For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, and an amine crosslinking agent. , Melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Is mentioned. When the (meth) acrylic acid ester polymer (A) has a hydroxyl group as a reactive functional group, among them, it is preferable to use an isocyanate-based crosslinking agent that is excellent in reactivity with a hydroxyl 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, etc. , 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 is preferable from the viewpoint of reactivity with hydroxyl groups.

The content of the crosslinking agent (C) is preferably 0.01 to 10 parts by weight, particularly 0.05 to 5 parts by weight, with respect to 100 parts by weight of the (meth) acrylic acid ester polymer (A). It is preferable that the amount is 0.1 to 1 part by mass.

(4) Various additives The active energy ray-curable adhesive component may be various additives, for example, a photopolymerization initiator, a silane coupling agent, a refractive index adjusting agent, an antistatic agent, a tackifier, an antioxidant, if desired. You may contain a ultraviolet absorber, a light stabilizer, a softening agent, a filler, etc.

In the case where ultraviolet rays are used as active energy rays for curing the adhesive composition P, the active energy ray-curable adhesive component preferably contains a photopolymerization initiator. By containing the photopolymerization initiator, the active energy ray-curable adhesive component can be efficiently cured, and the polymerization curing time and the irradiation amount of the active energy ray can be reduced.

Examples of the 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′-diethyla Nobenzophenone, 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 used in an amount in the range of 0.1 to 20 parts by weight, particularly 1 to 12 parts by weight with respect to 100 parts by weight of the active energy ray curable compound (B) in the active energy ray curable adhesive component. It is preferable to be used.

In addition, the active energy ray-curable adhesive component preferably contains a silane coupling agent from the viewpoint of improving the adhesive force of the obtained adhesive to the glass surface or the like. The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the adhesive component and having light transmittance.

Examples of such silane coupling agents 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 compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, etc. Elemental compound, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of them, and alkyl group such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Examples include condensates with silicon compounds. These may be used individually by 1 type and may be used in combination of 2 or more type.

The content of the silane coupling agent is preferably 0.01 to 10 parts by mass, particularly 0.05 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). More preferably, the content is 0.1 to 1 part by mass.

2. Light Diffusing Fine Particle The light diffusing fine particle contained in the pressure sensitive adhesive composition P according to the present embodiment has a refractive index difference of 0.005 to 0.2 with respect to the active energy ray-curable pressure sensitive adhesive component, and is determined by a centrifugal sedimentation light transmission method. The average particle size is 0.8 to 2.9 μm.

Examples of the light diffusing fine particles include inorganic fine particles such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc and titanium dioxide; organic fine particles such as acrylic resin, polystyrene resin, polyethylene resin and epoxy resin. Translucent fine particles; fine particles comprising a silicon-containing compound having an intermediate structure between inorganic and organic such as silicone resin (for example, Tospearl series manufactured by Momentive Performance Materials Japan). Among these, acrylic resin fine particles and fine particles made of a silicon-containing compound having an intermediate structure between inorganic and organic are preferable from the viewpoint of high definition of the pressure-sensitive adhesive layer. In addition, fine particles made of a silicon-containing compound having an intermediate structure between inorganic and organic are particularly preferable because they exert their effect even when added in a small amount and the adhesiveness of the active energy ray-curable adhesive component is maintained well. . The above light diffusing fine particles may be used alone or in combination of two or more.

Examples of the acrylic resin fine particles include those composed of a homopolymer of methyl methacrylate or a copolymer of monomers such as methyl methacrylate and vinyl acetate, styrene, methyl acrylate, and ethyl methacrylate. .

The shape of the light diffusing fine particles is preferably spherical fine particles with uniform light diffusion. The average particle diameter of the light diffusing fine particles by the centrifugal sedimentation light transmission method needs to be 0.8 to 2.9 μm, preferably 1 to 2.7 μm, particularly 1.2 to 2.2 μm. It is preferable. Thus, the average particle size of the light diffusing fine particles is relatively small, and due to the interaction between the above-mentioned active energy ray-curable adhesive component and the refractive index difference of the light diffusing fine particles, while having sufficient light diffusibility, A high-definition optical member with a pressure-sensitive adhesive layer in which glare is suppressed is obtained. When the average particle diameter of the light diffusing fine particles exceeds 2.9 μm, glare occurs in the optical member with the pressure-sensitive adhesive layer to which the obtained pressure-sensitive adhesive is applied. On the other hand, when the average particle size of the light diffusing fine particles is less than 0.8 μm, the light diffusibility becomes insufficient.

In addition, the average particle diameter by the centrifugal sedimentation light transmission method was obtained by sufficiently stirring 1.2 g of fine particles and 98.8 g of isopropyl alcohol as a measurement sample, and using a centrifugal automatic particle size distribution measuring apparatus (manufactured by Horiba, Ltd., Measured using CAPA-700).

The content of the light diffusing fine particles in the adhesive composition P is preferably 1 to 30 parts by mass, particularly 2 to 15 parts by mass with respect to 100 parts by mass of the active energy ray-curable adhesive component. And more preferably 6 to 12 parts by mass. When the content of the light diffusing fine particles is within the above range, the glare is effectively suppressed while having sufficient light diffusibility, and the adhesiveness of the active energy ray-curable adhesive component is not inhibited. .

3. Refractive Index Difference In the pressure-sensitive adhesive composition P according to the present embodiment, the difference in refractive index between the active energy ray-curable pressure-sensitive adhesive component and the light diffusing fine particles is from the viewpoint of achieving both light diffusibility and high definition. It needs to be 0.005 to 0.2, preferably 0.007 to 0.1, and particularly preferably 0.01 to 0.08. Thus, since the difference in refractive index between the active energy ray-curable adhesive component and the light diffusing fine particles is relatively small, high definition is facilitated.

The refractive index of the active energy ray-curable adhesive component is preferably 1.40 to 1.55, particularly preferably 1.42 to 1.50, and more preferably 1.44 to 1.49. It is preferable that Further, the refractive index of the light diffusing fine particles is preferably 1.40 to 1.55, particularly preferably 1.41 to 1.52, and further preferably 1.42 to 1.45. preferable.

Here, the refractive index of the active energy ray-curable adhesive component is a value measured according to JIS K0062 using an Abbe refractometer. In addition, since the refractive index of an active energy ray hardening adhesive component does not change before and after the curing, it may be a value measured before curing or a value measured after curing. On the other hand, the refractive index of the light diffusing fine particles is a value measured using a refractive index standard solution, as shown in a test example described later.

4). Method for Producing Adhesive Composition Adhesive composition P can be produced by mixing an active energy ray-curable adhesive component and light diffusing fine particles. When the active energy ray-curable adhesive component contains the (meth) acrylic acid ester polymer (A), the (meth) acrylic acid ester polymer (A) is first prepared, and the active energy ray-curable compound ( B), and optionally a cross-linking agent (C) and additives.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomer units 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, and 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 organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples thereof include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

In the polymerization step, the weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent 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 compound (B), the light diffusing fine particles, and optionally a crosslinking agent. (C) and an additive are added and mixed thoroughly to obtain an adhesive composition P (coating solution) diluted with a solvent.

Examples of the dilution solvent for diluting the adhesive composition P to form a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, methylene chloride, ethylene chloride, and the like. Halogenated hydrocarbons, alcohols such as methanol, ethanol, propanol, butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethyl A cellosolv solvent such as cellosolve is used.

The concentration / viscosity of the coating solution prepared in this manner is not particularly limited as long as it is within a coatable range, and can be appropriately selected according to the situation. For example, dilution is performed so that the concentration of the adhesive composition P is 10 to 40% by mass. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added.

[Adhesive]
The pressure-sensitive adhesive according to the present embodiment is obtained by curing the pressure-sensitive adhesive composition P. After the pressure-sensitive adhesive composition P is applied to a desired object and dried, the pressure-sensitive adhesive composition is irradiated with active energy rays. It can preferably be obtained by curing the product P.

Although drying of the adhesive composition P may be performed by air drying, it is usually performed by heat treatment (preferably hot air drying). In the case of performing the heat treatment, the heating temperature is preferably 50 to 150 ° C., particularly preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

As active energy rays, ultraviolet rays, electron beams and the like are usually used. The dose of the active energy ray varies depending on the type of the energy ray, for example, in the case of ultraviolet rays, preferably 50 ~ 1000mJ / cm ² in quantity, especially 100 ~ 500mJ / cm ² preferably. In the case of an electron beam, about 10 to 1000 krad is preferable.

When the active energy ray-curable adhesive component of the adhesive composition P contains the (meth) acrylic acid ester polymer (A), the active energy ray-curable compound (B), and the crosslinking agent (C), the adhesive composition By drying (heat treatment) of P, the (meth) acrylic acid ester polymer (A) is crosslinked with the crosslinking agent (C) to form a crosslinked structure. Moreover, by irradiating the adhesive composition P with active energy rays, the plurality of active energy ray-curable compounds (B) are bonded to each other to form a three-dimensional network structure, and are crosslinked by the crosslinking agent (C) (meta ) It is presumed that the acrylate polymer (A) is trapped in the three-dimensional network structure.

The haze value (value measured according to JIS K7105) of the pressure-sensitive adhesive according to this embodiment is preferably 10 to 80%, particularly preferably 20 to 70%, and more preferably 25 to 66%. Preferably there is. When the haze value is within the above range, the pressure-sensitive adhesive according to the present embodiment is more excellent in the glare suppression effect while being excellent in light diffusibility.

From the viewpoint of durability, the storage elastic modulus (G ′) at 80 ° C. of the pressure-sensitive adhesive according to this embodiment is preferably 0.2 to 5 MPa, particularly preferably 0.2 to 2 MPa. Further, it is preferably 0.3 to 1 MPa.

The storage elastic modulus (G ′) is a value measured by the following method.
<Method for measuring storage elastic modulus (G ′)>
A cylindrical test piece having a diameter of 8 mm and a thickness of 3 mm is prepared by laminating and punching the pressure-sensitive adhesive layer, and the storage elastic modulus (G ′) is measured by the torsional shear method under the following conditions.
Measuring device: Dynamic viscoelasticity measuring device “DYNAMIC ANALYZER RDAII” manufactured by Rheometric Co., Ltd.
Frequency: 1Hz
Temperature: 80 ° C

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 </ b> A according to the first embodiment is laminated on the pressure-sensitive adhesive layer 11, the pressure-sensitive adhesive layer 11 stacked on the release surface of the release sheet 12, and the pressure-sensitive adhesive layer 11. And the formed base material 13.

In addition, as shown in FIG. 2, the adhesive sheet 1B according to the second embodiment includes the two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. And the pressure-sensitive adhesive layer 11 sandwiched between the release sheets 12a and 12b. 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. .

In any of the pressure- sensitive adhesive sheets 1A and 1B, the pressure-sensitive adhesive layer 11 is made of a pressure-sensitive adhesive formed by curing the above-described pressure-sensitive adhesive composition P.

The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined according to the purpose of use of the pressure- sensitive adhesive sheets 1A and 1B, but is usually in the range of 5 to 100 μm, preferably 10 to 60 μm. For example, the pressure-sensitive adhesive for functional films When used as a layer, it is preferably 10 to 50 μm, more preferably 15 to 30 μm.

There is no restriction | limiting in particular as the base material 13, All can be used as a base material sheet of a normal adhesive sheet. For example, in addition to desired optical members, woven or non-woven fabrics using fibers such as rayon, acrylic, polyester, etc .; papers such as fine paper, glassine paper, impregnated paper, coated paper; metal foils such as aluminum and copper; urethane Foams, foams such as polyethylene foams; polyethylene terephthalate films, polybutylene terephthalate films, polyester films such as polyethylene naphthalate films, polyolefin films such as polyethylene films and polypropylene films, cellulose films such as triacetyl cellulose, polyvinyl chloride Film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polyurethane film, polystyrene film, polycarbonate film, acrylic resin film Lum, norbornene resin film, a plastic film such as a cycloolefin resin film; of two or more kinds of those laminates, and the like. The plastic film may be uniaxially stretched or biaxially stretched.

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 transflective film. Etc. Among these, since the polarizing plate (polarizing film) easily shrinks and has a large dimensional change, it is suitable as a target for forming the pressure-sensitive adhesive of the present embodiment (the pressure-sensitive adhesive layer 11) from the viewpoint of durability.

Although the thickness of the substrate 13 varies depending on the type, for example, in the case of an optical member, it is usually 10 to 500 μm, preferably 50 to 300 μm, and particularly preferably 80 to 150 μm.

As the release sheets 12, 12a, 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate 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, polyimide film A fluororesin film or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

The release surface of the release sheet (particularly the surface in contact with the pressure-sensitive adhesive layer 11) is preferably subjected to a release 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.

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

In order to manufacture the pressure-sensitive adhesive sheet 1A, a solution (coating solution) containing the pressure-sensitive adhesive composition P is applied to the release surface of the release sheet 12 and dried to form a coating layer of the pressure-sensitive adhesive composition P. A base material 13 is laminated on the coating layer. And it hardens | cures by irradiating an active energy ray to the said coating-film layer through the peeling sheet 12, and the adhesive layer 11 is formed. The active energy ray irradiation conditions are as described above.

Moreover, in order to manufacture the said adhesive sheet 1B, the coating solution containing the said adhesive composition P is apply | coated and dried on the peeling surface of one peeling sheet 12a (or 12b), and the coating film of the adhesive composition P After forming the layer, the other release sheet 12b (or 12a) is laminated on the coating layer. And it hardens | cures by irradiating the said coating-film layer to an active energy ray through the peeling sheet 12a (or 12b), and the adhesive layer 11 is formed.

Moreover, it replaces with forming an adhesive layer 11 by irradiating an active energy ray through a peeling sheet as mentioned above, and forms the coating-film layer of the adhesive composition P on a peeling sheet, The coating-film layer With the exposed state, the active energy ray may be irradiated to form the pressure-sensitive adhesive layer 11, and then a base material or a release sheet may be laminated on the pressure-sensitive adhesive layer 11. Furthermore, the adhesive layer 11 may be formed by directly forming a coating layer of the adhesive composition P on the substrate and irradiating the coating layer with active energy rays.

As a method for applying the coating solution, 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.

Here, for example, to manufacture a liquid crystal display device composed of a liquid crystal cell and a polarizing plate, a polarizing plate is used as the base material 13 of the pressure-sensitive adhesive sheet 1A, and the release sheet 12 of the pressure-sensitive adhesive sheet 1A is peeled off. What is necessary is just to bond the exposed adhesive layer 11 and a liquid crystal cell.

For example, in order to manufacture a liquid crystal display device in which a retardation plate is disposed between a liquid crystal cell and a polarizing plate, as an example, first, one release sheet 12a (or 12b) of the adhesive sheet 1B is released. Then, the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1B and the phase difference plate are bonded together. Next, the release sheet 12 of the pressure-sensitive adhesive sheet 1A using a polarizing plate as the base material 13 is peeled off, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1A and the retardation plate are bonded. Furthermore, the other release sheet 12b (or 12a) is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet B, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet B is bonded to the liquid crystal cell.

According to the above pressure- sensitive adhesive sheets 1A and 1B, a high-definition optical member with reduced glare can be obtained while exhibiting light diffusibility by the pressure-sensitive adhesive layer 11. In addition, since the pressure-sensitive adhesive layer 11 is extremely excellent in form stability, even when applied to adhesion of a polarizing plate, for example, deformation of the polarizing plate can be suppressed by the pressure-sensitive adhesive layer 11, thereby exhibiting high durability. It is estimated to be. Thereby, high-definition property, excellent temporal stability, and light diffusibility can be imparted to the optical member even in an environment where a heat history is applied.

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, the release sheet 12 of the adhesive sheet 1A may be omitted, or one of the release sheets 12a and 12b in the adhesive sheet 1B may be omitted.

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 to these examples and the like.

[Example 1]
1. Preparation of (meth) acrylic acid ester polymer 94.5 parts by mass of n-butyl acrylate, 5 parts by mass of acrylic acid and 0.5 parts by mass of 2-hydroxyethyl acrylate were copolymerized to give (meth) acrylic acid ester. A polymer (A) was prepared. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, the weight average molecular weight was 1.8 million.

2. Preparation of Adhesive Composition 83.5 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above step (converted to a solid content; the same applies hereinafter) and the active energy ray-curable compound (B) 15 parts by mass of tris (acryloxyethyl) isocyanurate (manufactured by Toa Gosei Co., Ltd., product name “Aronix M-315”; molecular weight 423) and trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent (C) , Product name “Coronate L”) 0.3 parts by mass and then mixed with benzophenone and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator at a mass ratio of 1: 1 (Ciba Specialty Chemicals) Product name “Irgacure 500”) 1.5 parts by mass, 3-glycidoxy as silane coupling agent 0.2 part by mass of propyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name “KBM-403”) (above, active energy ray-curable adhesive component), and intermediate between inorganic and organic as light diffusing fine particles Fine particles composed of silicon-containing compounds having a structure (manufactured by Momentive Performance Materials Japan, product name “Tospearl 120”, average particle size: 2.0 μm, refractive index: 1.43) 2.5 parts by mass (active 2.5 parts by mass) was added to 100 parts by mass of the energy ray-curable adhesive component, and the mixture was sufficiently stirred and diluted with ethyl acetate to obtain a coating solution of the adhesive composition.

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 (A)]
BA: n-butyl acrylate AA: acrylic acid HEA: 2-hydroxyethyl acrylate
[Light diffusion fine particles]
Silicone fine particles (2 μm): Fine particles composed of silicon-containing compounds having an intermediate structure between inorganic and organic (Momotive Performance Materials Japan, product name “Tospearl 120”, average particle size: 2.0 μm, refraction Rate: 1.430)
Silicone fine particles (4.5 μm): Fine particles composed of silicon-containing compounds having an intermediate structure between inorganic and organic (Momentive Performance Materials Japan, product name “Tospearl 145”, average particle size: 4.5 μm) , Refractive index: 1.430)
PMMA fine particles (2.5 μm): resin beads made of a crosslinked methacrylic acid polymer (manufactured by Sekisui Plastics Co., Ltd., product name “SSX102”, average particle size: 2.5 μm, refractive index: 1.490)
PMMA fine particles (4 μm): resin beads made of a crosslinked methacrylic acid polymer (manufactured by Sekisui Plastics Co., Ltd., product name “SSX104”, average particle size: 4.0 μm, refractive index: 1.490)
Styrene / acrylic copolymer fine particles (3.5 μm): resin beads made of a copolymer of styrene and an acrylic monomer (manufactured by Sekisui Plastics Co., Ltd., average particle size: 3.5 μm, refractive index: 1.555)

3. Production of polarizing plate with pressure-sensitive adhesive layer A release sheet (SP-PET3811, manufactured by Lintec Corporation, thickness) of a coating solution of the pressure-sensitive adhesive composition obtained in the above-described process was prepared by peeling one side of a polyethylene terephthalate film with a silicone-based release agent. : 38 μm) was applied to the release-treated surface with a knife coater, followed by heat treatment at 90 ° C. for 1 minute to form a coating layer of the adhesive composition.

Next, a polarizing plate made of a polarizing film with a discotic liquid crystal layer and integrated with a polarizing film and a viewing angle widening film was bonded to the exposed surface side of the coating layer. Then, the polarizing plate with an adhesive layer was obtained by irradiating an ultraviolet-ray on the following conditions through a peeling sheet, and making the said coating-film layer into an adhesive layer. In addition, the thickness of the formed adhesive layer was 25 micrometers.
<Ultraviolet irradiation conditions>
Fusion Co. electrodeless lamp H bulb used, illuminance 600 mW / cm ^2, light quantity 150 mJ / cm ²
・ UV illuminance / light meter uses "UVPF-36" manufactured by Eye Graphics.

[Examples 2 to 11, Comparative Examples 1 to 6]
Table 1 shows the blending amount of the (meth) acrylic acid ester polymer (A), the active energy ray-curable compound (B) and the photopolymerization initiator, the kind and blending amount of the light diffusing fine particles, and the thickness of the pressure-sensitive adhesive layer. A polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except for changing as shown.

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] (Calculation of refractive index)
The refractive index of the light diffusing fine particles used in Examples and Comparative Examples was measured by the following method. Fine particles were placed on a slide glass, a refractive index standard solution was dropped on the fine particles, and a cover glass was put on to prepare a sample. The sample was observed with a microscope, and the refractive index of the refractive index standard solution in which the outline of the fine particles was most difficult to see was taken as the refractive index of the fine particles.

On the other hand, the refractive index of the adhesive component used in Examples and Comparative Examples was measured by the following method. In each of the adhesive compositions of Examples and Comparative Examples, no light diffusing fine particles were added, and instead of the polarizing plate used for the preparation of the polarizing plate with the adhesive layer, one side of the polyethylene terephthalate film was replaced with a silicone-based release agent. The release sheet (SP-PET3801, manufactured by Lintec, thickness: 38 μm) was used, and the pressure-sensitive adhesive layer was 25 μm in thickness. Otherwise, the release sheet (SP-PET3801) / pressure-sensitive adhesive layer A pressure-sensitive adhesive sheet having a structure of (thickness: 25 μm) / release sheet (SP-PET3811) was produced.

A single pressure-sensitive adhesive layer obtained by peeling two release sheets from the pressure-sensitive adhesive sheet was used as a measurement sample. With respect to this measurement sample, the refractive index was measured according to JIS K0062-1992 using an Abbe refractometer, and this was taken as the refractive index of the active energy ray-curable adhesive component.

From the above measurement results, the refractive index difference between the active energy ray-curable adhesive component and the light diffusing fine particles was calculated. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)
Instead of the polarizing plate used for the preparation of the polarizing plate with the pressure-sensitive adhesive layer in Examples and Comparative Examples, a release sheet (SP-PET 3801, manufactured by Lintec Co., Ltd., thickness) on which one side of the polyethylene terephthalate film was treated with a silicone-based release agent. The pressure-sensitive adhesive sheet having a structure of release sheet (SP-PET3801) / adhesive layer / release sheet (SP-PET3811) was prepared.

About the adhesive layer of the obtained adhesive sheet, haze value (%) was measured according to JIS K7105 using the haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH2000). The results are shown in Table 2.

[Test Example 3] (Evaluation of definition)
A metal-deposited layer was provided on the glass plate, and a resist pattern and an etching process were performed to form a lattice pattern having a light transmission portion with a size of 60 ppi (pixels / inch). The glass plate provided with the lattice pattern was placed on a backlight (Bright Box 5000, manufactured by King Corp.).

Next, the release sheet of the polarizing plate with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples is peeled off, and placed on the lattice pattern so that the polarizing plate side of the polarizing plate with the pressure-sensitive adhesive layer is down, The location where glare occurred was confirmed. And when the polarizing plate with the pressure-sensitive adhesive layer is moved in a direction parallel to the glass plate on the lattice pattern, and the occurrence of glare that has been confirmed in advance has moved together with the polarizing plate with the pressure-sensitive adhesive layer, It was judged that the occurrence of the glare was due to the polarizing plate with the pressure-sensitive adhesive layer.

In addition, when the occurrence of glare due to the polarizing plate with the adhesive layer was not confirmed in the lattice pattern of 60 ppi, the occurrence of glare due to the lattice pattern of 70 ppi and still the polarizing plate with the adhesive layer was observed. If it was not confirmed, the same operation was performed until the occurrence of glare caused by the polarizing plate with the pressure-sensitive adhesive layer was confirmed using a lattice pattern of 10 ppi in sequence, such as a lattice pattern of 80 ppi. Went. Table 2 shows the largest lattice pattern (ppi) of ppi in which the occurrence of glare due to the polarizing plate with the pressure-sensitive adhesive layer is not confirmed.

Here, the glare caused by the polarizing plate with the pressure-sensitive adhesive layer is more likely to occur as ppi in the lattice pattern increases, in other words, as the display becomes higher definition. Therefore, it means that generation | occurrence | production of glare can be suppressed effectively, so that the value of ppi shown in Table 2 is large. In addition, what exceeds 100 ppi can be called a high-definition polarizing plate.

[Test Example 4] (Durability evaluation)
The polarizing plate with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut into a size of 233 mm × 309 mm using a cutting device (Super Cutter manufactured by Hadano Seisakusho, PN1-600). After peeling off the release sheet from the above polarizing plate with the pressure-sensitive adhesive layer and pasting the exposed pressure-sensitive adhesive layer on alkali-free glass (Corning Corp., Eagle XG), 0.5 MPa and 50 ° C. in an autoclave manufactured by Kurihara Seisakusho, The sample was pressurized for 20 minutes and used as an evaluation sample.

The evaluation sample was put in an environment of 80 ° C. in a dry state (relative humidity of less than 35%) for 500 hours, and then the presence or absence of lifting or peeling was confirmed using a 10 × loupe. And durability was evaluated by the following evaluation criteria. The results are shown in Table 2.
A: No lifting or peeling was confirmed.
○: Lifting or peeling of a size of 0.5 mm or less was confirmed.
X: Floating or peeling of a size exceeding 0.5 mm was confirmed.

[Test Example 5] (Measurement of storage elastic modulus)
A pressure-sensitive adhesive layer having a thickness of 30 μm was formed in the same manner as each example or comparative example. After laminating this pressure-sensitive adhesive layer, punching was performed to prepare a cylindrical test piece having a diameter of 8 mm and a thickness of 3 mm. About this test piece, the storage elastic modulus (G ') (MPa) in 80 degreeC was measured by the torsional shear method on the following conditions. The results are shown in Table 2.
Measuring device: Dynamic viscoelasticity measuring device “DYNAMIC ANALYZER RDAII” manufactured by Rheometric Co., Ltd.
Frequency: 1Hz
Temperature: 80 ° C

As can be seen from Table 2, the refractive index difference between the active energy ray-curable adhesive component and the light diffusing fine particles is in the range of 0.005 to 0.2, and the average particle size of the light diffusing fine particles is 0.8 to 2. The polarizing plate with the pressure-sensitive adhesive layer of the example in the range of 9 μm is capable of obtaining a high-definition optical member having light diffusibility and further suppressing glare while having sufficient durability. did it.

The pressure-sensitive adhesive composition, pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present invention are suitable for providing an optical member having high definition and light diffusibility.

1A, 1B ... Adhesive sheet 11 ... Adhesive layer 12, 12a, 12b ... Release sheet 13 ... Base material

Claims (9)

1. An active energy ray-curable adhesive component;
   Containing light diffusing fine particles,
   The difference between the refractive index of the active energy ray-curable adhesive component and the refractive index of the light diffusing fine particles is 0.005 to 0.2,
   An adhesive composition, wherein the light diffusing fine particles have an average particle diameter of 0.8 to 2.9 μm by a centrifugal sedimentation light transmission method.
2. The pressure-sensitive adhesive composition according to claim 1, wherein the active energy ray-curable pressure-sensitive adhesive component contains a (meth) acrylic acid ester polymer and an active energy ray-curable compound.
3. The pressure-sensitive adhesive composition according to claim 2, wherein the active energy ray-curable compound is a polyfunctional acrylate monomer having a molecular weight of 1000 or less.
4. The active energy ray-curable adhesive component further contains a crosslinking agent,
   The said (meth) acrylic acid ester polymer contains the monomer which has a functional group which reacts with the said crosslinking agent as a monomer unit which comprises the said polymer, The adhesiveness of Claim 2 or 3 characterized by the above-mentioned. Composition.
5. The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the light diffusing fine particles are fine particles comprising a silicon-containing compound having an intermediate structure between inorganic and organic.
6. A pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to any one of claims 1 to 5.
7. The pressure-sensitive adhesive according to claim 6, having a haze value of 10 to 80%.
8. A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer,
   The said adhesive layer consists of an adhesive of Claim 6 or 7, The adhesive sheet characterized by the above-mentioned.
9. Two release sheets,
   An adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets;
   The said adhesive layer consists of an adhesive of Claim 6 or 7, The adhesive sheet characterized by the above-mentioned.

Images