JP2017014376A - Adhesive composition for optical member, optical laminate and surface light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition capable of providing an adhesive layer having high refractive index, transparency and adhesiveness.SOLUTION: There is provided an adhesive composition for an optical member which comprises an acrylic polymer, inorganic particles, a plasticizer and a silane coupling agent, wherein the acrylic polymer is a copolymer of a copolymerization component containing 40 wt.% to 93 wt.% of an aromatic ring-containing acrylic monomer and 7 wt.% to 60 wt.% of a hydroxyl group-containing monomer and has a weight average molecular weight of 200000 or less, the silane coupling agent has an epoxy group, the inorganic particles have a volume-average particle diameter of 1 nm or more and 15 nm or less and the amount of the inorganic particles is 82 pts.wt. or more and 100 pts.wt. or less based on 100 pts.wt. of the acrylic polymer.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition for optical members, and an optical laminate and a surface light source device using the same.

  A surface light source device including an organic electroluminescence element (hereinafter, appropriately referred to as “organic EL element”) includes a surface light emitter including an organic EL element and a light extraction film (light extraction efficiency) provided on the light emitting surface of the surface light emitter. A film having a concavo-convex structure for enhancing the surface) and an adhesive layer for bonding the surface light emitter and the light extraction film in some cases (for example, see Patent Document 1). According to such a surface light source device, the light generated in the organic EL element is emitted outside the device through the adhesive layer and the light extraction film.

International Publication No. 2011/078092

  In the surface light source device as described above, it is particularly advantageous to increase the light extraction efficiency when the adhesive layer has a high refractive index. Therefore, in order to develop a high refractive index in the pressure-sensitive adhesive layer, the use of a pressure-sensitive adhesive composition containing inorganic particles, which are high refractive index materials, has been studied as a pressure-sensitive adhesive composition included in the pressure-sensitive adhesive layer.

  When a pressure-sensitive adhesive composition containing inorganic particles having a high refractive index is used, it is possible to realize a high refractive index pressure-sensitive adhesive layer. However, depending on the size of the inorganic particles, the transparency of the adhesive layer may decrease due to the use of the inorganic particles. Further, when the compatibility between the pressure-sensitive adhesive contained in the pressure-sensitive adhesive composition and the inorganic particles is not good, it may be gelled and cannot be used. Furthermore, even when a pressure-sensitive adhesive having high compatibility with inorganic particles is used, if the amount of inorganic particles is increased to achieve a high refractive index, the adhesive strength may be lowered. As a specific example, the light emitting surface of a surface light emitter including an organic EL element is generally formed of glass, but the pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing a large amount of inorganic particles is made of the glass described above. There was a tendency for the adhesiveness to the light emitting surface to be low. Therefore, a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer is required to have a high refractive index, a high transparency, and a sufficient pressure-sensitive adhesive property.

  The present invention was devised in view of the above-mentioned problems, and is a pressure-sensitive adhesive composition that can realize a pressure-sensitive adhesive layer having high refractive index, transparency, and adhesiveness; and any of refractive index, transparency, and adhesiveness. An object of the present invention is to provide an optical laminate and a surface light source device having a high adhesive layer.

As a result of intensive studies to solve the above-mentioned problems, the inventor is an acrylic polymer obtained by copolymerizing a copolymer component containing a predetermined amount of an aromatic ring-containing acrylic monomer and a predetermined amount of a hydroxyl group-containing monomer, It has been found that those having a weight average molecular weight in a predetermined range have both a high refractive index and a high tackiness. Furthermore, the present inventor has found that the above-mentioned problems can be solved by combining the acrylic polymer with inorganic particles, a plasticizer, and a silane coupling agent containing an epoxy group under predetermined conditions. Was completed.
That is, the present invention is as follows.

[1] Including an acrylic polymer, inorganic particles, a plasticizer, and a silane coupling agent,
The acrylic polymer is a copolymer of copolymer components including 40% to 93% by weight of an aromatic ring-containing acrylic monomer and 7% to 60% by weight of a hydroxyl group-containing monomer, and the weight average molecular weight thereof is 200,000 or less,
The silane coupling agent contains an epoxy group,
The volume average particle diameter of the inorganic particles is 1 nm or more and 15 nm or less,
The pressure-sensitive adhesive composition for an optical member, wherein the amount of the inorganic particles is from 82 parts by weight to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer.
[2] The pressure-sensitive adhesive composition for optical members according to [1], wherein the amount of the plasticizer is 11 to 17 parts by weight with respect to 100 parts by weight of the acrylic polymer.
[3] The pressure-sensitive adhesive composition for optical members according to [1] or [2], wherein the plasticizer has a melting point of 0 ° C. or lower.
[4] The pressure-sensitive adhesive composition for optical members according to any one of [1] to [3], wherein the plasticizer is selected from the group consisting of ester plasticizers.
[5] The pressure-sensitive adhesive composition for an optical member according to any one of [1] to [4], wherein the plasticizer is an aromatic ring-containing ester.
[6] The pressure-sensitive adhesive composition for optical members according to any one of [1] to [5], wherein the refractive index is 1.58 or more.
[7] A substrate and a pressure-sensitive adhesive layer formed on the substrate,
The optical laminated body in which the said adhesion layer contains the adhesive composition for optical members of any one of [1]-[6].
[8] a surface light emitter having a light emitting surface;
And an optical laminate according to [7],
A surface light source device in which the adhesive layer is attached to the light emitting surface.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can implement | achieve an adhesive layer with high refractive index, transparency, and adhesiveness; and the optical laminated body provided with the adhesive layer with high refractive index, transparency, and adhesiveness And a surface light source device.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be implemented with any modifications without departing from the scope of the claims of the present invention and its equivalents.

  In the following description, unless otherwise specified, the “solvent” is not only a medium in which a solute is dissolved, but also a suspension (slurry) in which a dispersion is dispersed, as well as a medium constituting the solution. It is also used as a term that includes a medium that constitutes a

  In the following description, “compatibility” between a certain substance and another substance is defined as a solution or suspension obtained by mixing these substances and a solvent as necessary, unless otherwise specified. These are properties that maintain a homogeneous state without causing gelation or separation.

  In the following description, unless otherwise specified, “(meth) acryl” is a term including acryl and methacryl, “(meth) acryloyl” is a term including acryloyl and methacryloyl, and “( “Meth) acrylate” is a term including acrylate and methacrylate, and “acrylic polymer” is a polymer having a structure obtained by polymerizing a monomer component containing at least one (meth) acrylic monomer. It is a term that means coalescence.

[1. Outline of adhesive composition]
The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition for an optical member containing an acrylic polymer, inorganic particles, a plasticizer, and a silane coupling agent. In the present application, a pressure-sensitive adhesive composition having fluidity like a slurry and a cured pressure-sensitive adhesive composition are referred to as “pressure-sensitive adhesive composition” without distinction. This pressure-sensitive adhesive composition is usually formed into a layer and used to bond optical members together. Hereinafter, the layer formed of the pressure-sensitive adhesive composition may be referred to as “pressure-sensitive adhesive layer” as appropriate. Thus, in the state as the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition has a high refractive index, high transparency, and high adhesiveness.

[2. Acrylic polymer]
The acrylic polymer is a copolymer of copolymer components including an aromatic ring-containing acrylic monomer and a hydroxyl group-containing monomer. Hereinafter, the copolymerization component containing an aromatic ring-containing acrylic monomer and a hydroxyl group-containing monomer may be appropriately referred to as “copolymerization component [I]”. Moreover, the said copolymerization component [I] can contain a (meth) acrylic-acid alkylester type monomer and arbitrary copolymerizable monomers as needed.

The aromatic ring-containing acrylic monomer can be a compound having one or more aromatic rings and one or more ethylenically unsaturated groups in one molecule.
Examples of the functional group containing an ethylenically unsaturated group include a (meth) acryloyl group, a crotonoyl group, a vinyl group, an allyl group, and the like. Among these, a (meth) acryloyl group is preferable in terms of excellent reactivity.

  Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a biphenyl ring, and a fluorene ring. The number of aromatic rings per molecule of the aromatic ring-containing acrylic monomer may be one or plural. The aromatic ring-containing acrylic monomer is preferably a compound containing one aromatic ring per molecule from the viewpoint that the physical properties of the adhesive can be balanced. Moreover, it is preferable that it is a compound containing two aromatic rings per molecule from the point which can control the refractive index and birefringence of an adhesion layer efficiently.

Examples of the aromatic ring-containing acrylic monomer include benzyl (meth) acrylate, benzyloxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and ethylene oxide-modified (meth) acrylic. Examples include acid cresol, ethylene oxide-modified (meth) acrylic acid nonylphenol, (meth) acrylic acid biphenyloxyethyl ester, and styrene. Of these, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferred.
An aromatic ring containing acrylic monomer may be used individually by 1 type, and may be used combining 2 or more types by arbitrary ratios.

  The amount of the aromatic ring-containing acrylic monomer in the copolymerization component [I] is usually 40% by weight or more, preferably 50% by weight or more, more preferably 55% by weight or more, particularly with respect to the entire copolymerization component [I]. Preferably it is 60 weight% or more, and is 93 weight% or less normally, Preferably it is 90 weight% or less, More preferably, it is 85 weight% or less. By making the amount of the aromatic ring-containing acrylic monomer more than the lower limit of the above range, it is possible to introduce a large number of aromatic rings into the acrylic polymer and increase its refractive index. Can be expensive. Moreover, since the adhesiveness of an acrylic polymer can be exhibited by making the amount of the aromatic ring-containing acrylic monomer not more than the upper limit of the above range, the adhesiveness of the adhesive composition can be improved.

A hydroxyl group-containing monomer is a monomer containing a hydroxyl group. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meta ) Hydroxyalkyl esters of acrylic acid such as acrylate, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, oxyalkylene-modified monomers such as diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate; 2-acryloyloxy Primary hydroxyl group-containing monomers such as ethyl 2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, and hydroxyethylacrylamide; 2-hydroxy Secondary hydroxyl group-containing monomers such as propyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate; 3 such as 2,2-dimethyl 2-hydroxyethyl (meth) acrylate Mention may be made of secondary hydroxyl group-containing monomers.
A hydroxyl-containing monomer may be used individually by 1 type, and may be used combining 2 or more types by arbitrary ratios.

  Among the hydroxyl group-containing monomers, the primary hydroxyl group-containing monomer is preferable in terms of excellent reactivity with the crosslinking agent. A monomer having a hydroxyl group at the end of the molecular chain is preferable because it tends to exhibit superior antistatic performance. Furthermore, it is particularly preferable to use 2-hydroxyethyl (meth) acrylate because it has few impurities such as di (meth) acrylate and is easy to produce.

The hydroxyl group-containing monomer preferably has a low content of di (meth) acrylate, which is an impurity. Specifically, the content ratio of the di (meth) acrylate of the hydroxyl group-containing monomer is preferably 0.5% by weight or less, more preferably 0.2% by weight or less, and particularly preferably 0.1% by weight or less.
Particularly preferred hydroxyl group-containing monomers include 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate.

  The amount of the hydroxyl group-containing monomer in the copolymerization component [I] is usually 7% by weight or more, preferably 10% by weight or more, and usually 60% by weight or less, preferably 50% by weight based on the entire copolymerization component [I]. % Or less, more preferably 40% by weight or less, and particularly preferably 35% by weight or less. By making the amount of the hydroxyl group-containing monomer at least the lower limit of the above range, the compatibility between the acrylic polymer and the inorganic particles can be improved, so that the dispersibility of the inorganic particles in the pressure-sensitive adhesive composition can be improved, By making it below the upper limit of the range, the amount of the aromatic ring-containing acrylic monomer can be relatively increased to increase the refractive index of the pressure-sensitive adhesive composition.

  The weight ratio (a1) :( a2) of the aromatic ring-containing acrylic monomer and the hydroxyl group-containing monomer is preferably 93: 7 to 40:60, more preferably 90:10 to 50:50, and still more preferably 85. 15 to 60:40. The refractive index of the pressure-sensitive adhesive composition can be effectively increased by increasing the amount of the aromatic ring-containing acrylic monomer relative to the hydroxyl group-containing monomer as described above. In addition, since the compatibility between the acrylic polymer and the inorganic particles can be improved by reducing the amount of the aromatic ring-containing acrylic monomer relative to the hydroxyl group-containing monomer as described above, the dispersion of the inorganic particles in the pressure-sensitive adhesive composition can be improved. Can be improved.

  As the (meth) acrylic acid alkyl ester monomer, those in which the number of carbon atoms of the alkyl group of the (meth) acrylic acid alkyl ester monomer is within a predetermined range are preferable. Specifically, the number of carbon atoms of the alkyl group is usually 1 or more, preferably 4 or more, preferably 20 or less, more preferably 12 or less, and particularly preferably 8 or less.

Examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, Examples include stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
One (meth) acrylic acid alkyl ester monomer may be used alone, or two or more may be used in combination at any ratio.

  Among the (meth) acrylic acid alkyl ester monomers, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are copolymerizable, adhesive properties, easy handling, and easy to obtain raw materials. N-butyl (meth) acrylate is particularly preferable from the viewpoint of excellent durability.

  The amount of the (meth) acrylic acid alkyl ester monomer in the copolymerization component [I] is preferably 0 to 40% by weight, more preferably 0 to 35% by weight, particularly preferably based on the entire copolymerization component [I]. Is from 0 to 30% by weight. By using the (meth) acrylic acid ester monomer (a3) in such a range, the adhesiveness of the adhesive composition can be effectively increased.

  Examples of the optional copolymerizable monomer include monomers other than the aromatic ring-containing acrylic monomer, the hydroxyl group-containing monomer, and the (meth) acrylic acid alkyl ester monomer. For example, a carboxyl group-containing monomer, an amino group-containing monomer, Examples thereof include functional group-containing monomers such as acetoacetyl group-containing monomers, isocyanate group-containing monomers, and glycidyl group-containing monomers.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, and cinnamic acid. Among them, (meth) acrylic acid is preferably used.

  Examples of the amino group-containing monomer include t-butylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and the like.

  Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

  Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

  Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, allyl glycidyl (meth) acrylate, and the like.

  Moreover, when it is desired to increase the molecular weight of the acrylic polymer, a compound having two or more ethylenically unsaturated groups may be used. Examples of the compound having two or more ethylenically unsaturated groups include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and propylene glycol. Examples include di (meth) acrylate and divinylbenzene.

  As an arbitrary copolymerizable monomer, an acidic group-containing monomer such as a carboxyl group-containing monomer may be used as long as the effects of the present invention are not significantly impaired. However, from the viewpoint of corrosion resistance, it is preferable not to use an acidic group-containing monomer.

Examples of optional copolymerizable monomers further include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2- Butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene Glycol-polypropylene glycol-mono (meth) acrylate, lauroxypolyethylene glycol mono (meth) acrylate, stearoxy Monomers containing alkoxy groups and oxyalkylene groups such as reethylene glycol mono (meth) acrylate; methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxymethyl (meth) acrylamide, isopropoxymethyl (meth) acrylamide, n -Alkoxyalkyl (meth) acrylamide monomers such as butoxymethyl (meth) acrylamide and isobutoxymethyl (meth) acrylamide; (meth) acryloylmorpholine, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth) acrylamide N- (Meth) acrylamide monomers such as methylol (meth) acrylamide; acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, Vinyl thearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, Examples include allyltrimethylammonium chloride and dimethylallyl vinyl ketone.
Arbitrary copolymerizable monomers may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the optional copolymerizable monomer in the copolymerization component [I] is preferably 0 to 40% by weight, more preferably 0 to 30% by weight, particularly preferably 0 to 0%, based on the entire copolymerization component [I]. 20% by weight. By using any copolymerizable monomer in such a range, the refractive index of the pressure-sensitive adhesive composition can be effectively increased by relatively increasing the amount of the aromatic ring-containing acrylic monomer.

  The acrylic polymer is produced by polymerizing monomer components such as an aromatic ring-containing acrylic monomer and a hydroxyl group-containing monomer, and a (meth) acrylic acid alkyl ester monomer and any copolymerizable monomer that can be used as necessary. it can. In the polymerization, for example, polymerization methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be employed. Among these, solution radical polymerization is preferable.

  Appropriate conditions that allow the polymerization reaction to proceed can be adopted as the polymerization conditions. For example, in an organic solvent, a polymerized monomer such as an aromatic ring-containing acrylic monomer, a hydroxyl group-containing monomer, a (meth) acrylic acid alkyl ester monomer and any copolymerizable monomer, and a polymerization initiator are mixed or dropped. An acrylic polymer can be produced by performing radical polymerization under reflux conditions or conditions of 50 ° C. to 90 ° C. usually for 2 hours to 20 hours.

  Examples of the organic solvent used for such polymerization include aromatic hydrocarbons such as toluene and xylene; esters such as methyl acetate, ethyl acetate, and butyl acetate; aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; One of these may be used alone, or two or more of these may be used in combination at any ratio.

  Examples of the polymerization initiator used in such polymerization include azo polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile; benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene And peroxide polymerization initiators such as hydroperoxide; One of these may be used alone, or two or more of these may be used in combination at any ratio.

  The weight average molecular weight of the acrylic polymer is usually 200,000 or less, preferably 180,000 or less, more preferably 160,000 or less, and particularly preferably 150,000 or less. By making the weight average molecular weight of the acrylic polymer below the upper limit of the above range, the compatibility between the acrylic polymer and the inorganic particles can be improved, so that the dispersibility of the inorganic particles in the pressure-sensitive adhesive composition is improved. it can. The lower limit of the weight average molecular weight of the acrylic polymer is arbitrary as long as the effect of the present invention is not significantly impaired, and is usually 10,000 or more.

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic polymer is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, and particularly preferably 5 or less. By setting the degree of dispersion of the acrylic polymer below the upper limit of the above range, the durability of the pressure-sensitive adhesive composition can be improved. The lower limit of the dispersity is arbitrary, but is usually 1.1 or more from the viewpoint of production limit.

The weight average molecular weight and the number average molecular weight are weight average molecular weights in terms of standard polystyrene molecular weight. This weight average molecular weight was measured by high performance liquid chromatography (manufactured by Waters, Japan, “Waters 2695 (main body)” and “Waters 2414 (detector)”), column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plate / piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) Can be done. The degree of dispersion can be determined from the weight average molecular weight and the number average molecular weight.

  The glass transition temperature of the acrylic polymer is preferably −70 ° C. or higher, more preferably −50 ° C. or higher, particularly preferably −40 ° C. or higher, preferably 10 ° C. or lower, more preferably 5 ° C. or lower, particularly preferably. Is 0 ° C. or lower. The heat resistance of the pressure-sensitive adhesive composition can be increased by setting the glass transition temperature of the acrylic polymer to be equal to or higher than the lower limit value of the range, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive composition can be decreased to the upper limit value of the range. Can be prevented from becoming too high.

The glass transition temperature of the acrylic polymer which is a copolymer can be calculated from the Fox equation shown in the following (1).
1 / Tg = Wa / Tga + Wb / Tgb +... Wn / Tgn (1)
Tg: Glass transition temperature of copolymer (K)
Tga: Glass transition temperature (K) of homopolymer of monomer A
Wa: weight fraction of monomer A Tgb: glass transition temperature (K) of homopolymer of monomer B
Wb: weight fraction of monomer B Tgn: glass transition temperature (K) of homopolymer of monomer N
Wn: weight fraction of monomer N (Wa + Wb +... + Wn = 1)

[3. Inorganic particles]
The inorganic particles are particles containing an inorganic material and are usually dispersed in the pressure-sensitive adhesive composition. In general, the refractive index of an inorganic material is high. Therefore, the pressure-sensitive adhesive composition containing inorganic particles within a range that does not impair the adhesive strength can achieve a high refractive index.

  As the inorganic material contained in the inorganic particles, it is preferable to use inorganic oxides such as metal oxides and non-metal oxides, and it is particularly preferable to use metal oxides. Furthermore, when using the particle | grains containing a metal oxide as an inorganic particle, the particle | grains containing the metal oxide and the organic substance which has the reactive functional group which modifies the surface as an inorganic particle are preferable. More specifically, coated particles containing metal oxide particles and an organic substance having a reactive functional group that modifies the surface of the particles (hereinafter sometimes referred to as “reactive modified metal oxide particles” as appropriate). .) Is preferred. The reactive functional group may be in a state having an interaction such as a hydrogen bond with the metal oxide, or may be in a state capable of interacting with another substance without being in such a state.

As the metal oxide, a metal oxide that can be generally used as a filler in a resin is preferable. Examples of such metal oxides include zirconium oxide (ZrO ₂ : zirconia), titanium oxide (TiO ₂ : titania), aluminum oxide (Al ₂ O ₃ : alumina), iron oxide (Fe ₂ O ₃ , Fe _3). O ₄ ), copper oxide (CuO), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ : yttria), niobium oxide (Nb ₂ O ₅ ), molybdenum oxide (MoO ₃ , MoO ₂ ), indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), tantalum oxide (Ta ₂ O ₅ , TaO ₂ ), tungsten oxide (WO ₃ , WO ₂ ), lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ), oxidation Cerium (CeO ₂ : ceria), antimony oxide (Sb ₂ O ₃ , Sb ₂ O ₅ ), tin-doped indium oxide (ITO), antimony Examples include silicon tin oxide (ATO), fluorine-doped tin oxide (FTO), phosphorus-doped tin oxide (PTO), zinc antimonate (AZO), indium-doped zinc oxide (IZO), aluminum-doped zinc oxide, and gallium-doped zinc oxide. It is done.

As the non-metal oxide, a non-metal oxide that can be generally used as a filler in a resin is preferable. Examples of such non-metal oxides include silicon oxide (SiO ₂ : silica) and boron oxide (B ₂ O ₃ ).

  One kind of the metal oxide and the nonmetal oxide may be used alone, or two or more kinds may be used in combination at any ratio.

Among the inorganic materials, those having a high refractive index are preferable, and specifically those having a refractive index of 1.5 or more are preferable. By using a material having a high refractive index in this way, the amount of inorganic particles in the pressure-sensitive adhesive composition can be reduced, and thus the pressure-sensitive adhesiveness can be sufficiently increased. Examples of the high refractive index inorganic material include titanium oxide (refractive index: 2.3 to 2.7), potassium titanate (refractive index: 2.68), and zirconium oxide (refractive index: 2.05 to 2. 4), zinc oxide (refractive index: 2.01 to 2.03) and the like. Among these, zirconium oxide (ZrO ₂ : zirconia) and titanium oxide (TiO ₂ : titania) are preferable because a highly refractive adhesive composition can be easily obtained.

  Examples of the reactive functional group in the organic substance having a reactive functional group include a hydroxyl group, a phosphate group, a carboxyl group, an amino group, an alkoxy group, an isocyanate group, an acid halide, an acid anhydride, a glycidyl group, a chlorosilane group, and an alkoxy group. A silane group is mentioned. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  As the organic substance having a reactive functional group, an organic substance having an isocyanate group is preferable because stability of the metal oxide and the surrounding substance can be improved. Examples of organic substances having an isocyanate group include acryloxymethyl isocyanate, methacryloxymethyl isocyanate, acryloxyethyl isocyanate, methacryloxyethyl isocyanate, acryloxypropyl isocyanate, methacryloxypropyl isocyanate, 1,1-bis (acryloxymethyl) Ethyl isocyanate is mentioned. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  In the reactive modified metal oxide particles, the proportion of the organic substance having a reactive functional group is preferably 1 to 40 parts by weight with respect to 100 parts by weight of the metal oxide.

  Reactive modified metal oxide particles are mixed with metal oxide particles, organic substances having reactive functional groups, organic solvents and optional additives that can be used as necessary, and further necessary in the resulting mixture. Accordingly, by performing treatment such as ultrasonic treatment, a suspension in which particles are dispersed in an organic solvent can be obtained.

  Examples of the organic solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, methanol, ethanol, isopropyl alcohol, n-butanol, iso-butanol and the like Alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and other ethers, ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether Esters such as acetate and propylene glycol monoethyl ether acetate, dimethylforma De, N, N- dimethyl acetoacetamide, amides such as N- methylpyrrolidone. An organic solvent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  As an arbitrary additive, a metal chelating agent can be mentioned, for example. Arbitrary additives may be used alone or in combination of two or more at any ratio.

  When the reactive modified metal oxide particles are obtained as a suspension in which the particles are dispersed in an organic solvent, conditions such as the amount of the solvent are adjusted, and the reactive modified metal oxide particles are 1 in the suspension. It is preferable to adjust so that it may be contained by weight%-50weight%. The suspension thus obtained is preferably used as it is for the production of the pressure-sensitive adhesive composition from the viewpoint of ease of production.

  In preparing the mixture, each component is preferably mixed by a bead mill or the like. By such mixing, secondary particles or higher order particles can be pulverized to the primary particle level, and the surface can be treated in the state of primary particles. As a result, uniform surface treatment can be performed on the metal oxide particles.

  If necessary, the mixture may be further subjected to ultrasonic treatment. The ultrasonic treatment can be performed using an ultrasonic treatment device such as an ultrasonic cleaner, an ultrasonic homogenizer, an ultrasonic disperser or the like. By such treatment, a good suspension can be obtained.

  Commercially available particles may be used as they are as the reactive modified metal oxide particles. Although the said commercially available particle | grain may be provided as a slurry containing components, such as a solvent and an additive, it can be used as a material of an adhesive composition in the state of the slurry containing this component as it is.

The volume average particle diameter of the inorganic particles is usually 1 nm or more, preferably 2 nm or more, more preferably 3 nm or more, and usually 15 nm or less, preferably 10 nm or less, more preferably 8 nm or less. By making the volume average particle diameter of the inorganic particles equal to or greater than the lower limit of the above numerical range, the refractive index of the pressure-sensitive adhesive composition can be effectively increased while improving the dispersion of the inorganic particles, and the above range. The transparency of the pressure-sensitive adhesive composition can be made favorable by setting it to the upper limit value or less. When inorganic particles are aggregated to form secondary particles or higher order particles, the particle size range may be the primary particle size range.
The volume average particle diameter can be measured by using a dynamic light scattering particle size distribution analyzer (Nanotrac Wave-EX150, manufactured by Nikkiso Co., Ltd.) and using the volume as a particle diameter standard.

  Examples of the inorganic particle include fine particle powder, paste, or sol. Among these, the inorganic particle is preferably a sol.

  The amount of the inorganic particles is usually 82 parts by weight or more, preferably 85 parts by weight or more, more preferably 88 parts by weight or more, and usually 100 parts by weight or less, preferably 95 parts by weight with respect to 100 parts by weight of the acrylic polymer. Part or less, more preferably 90 parts by weight or less. The refractive index can be effectively increased by setting the amount of the inorganic particles to be equal to or higher than the lower limit value of the range, and the adhesiveness can be effectively increased by setting the amount of the inorganic particles to be equal to or lower than the upper limit value of the range.

[4. Plasticizer]
The plasticizer can be used to lower the viscosity of the pressure-sensitive adhesive composition and increase the pressure-sensitive adhesiveness. In general, when the acrylic polymer has a rigid structure such as an aromatic ring in the molecule, the viscosity tends to increase, and as a result, the adhesiveness tends to decrease. On the other hand, the pressure-sensitive adhesive composition containing a plasticizer can increase the adhesiveness. Therefore, it is possible to achieve both high refractive index and high adhesiveness.

  The melting point of the plasticizer is preferably 0 ° C. or lower, and more preferably −10 ° C. or lower. The lower limit of the melting point is preferably −70 ° C. or higher, and more preferably −60 ° C. or higher. When the melting point of the plasticizer is within this range, the compatibility of the components contained in the pressure-sensitive adhesive composition is excellent, and there is no adhesive residue of the pressure-sensitive adhesive composition, and appropriate pressure-sensitive adhesiveness can be obtained. Here, the adhesive residue is a phenomenon in which the adhesive composition remains on an arbitrary member when the adhesive layer containing the adhesive composition is bonded to an arbitrary member and then peeled off from the arbitrary member. Say.

  Examples of the plasticizer include polybutene, vinyl ether plasticizer, polyether plasticizer (including polyalkylene oxide and functionalized polyalkylene oxide), ester plasticizer, polyol plasticizer (for example, glycerin), and petroleum resin. , Hydrogenated petroleum resins, and styrene compounds (for example, α-methylstyrene). Among them, a plasticizer selected from the group consisting of ester plasticizers is preferable because of its good miscibility with acrylic polymers, and the refractive index of the adhesive layer can be easily increased. Aromatic ring-containing esters such as acid esters are more preferred, and benzoic acid esters are particularly preferred.

Benzoic acid esters that can be used as plasticizers include, for example, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, benzyl benzoate, and 1,4-cyclohexanedimethanol dibenzoate, and among them, dipropylene glycol dibenzoate and benzyl benzoate. Is particularly preferred.
Examples of the phthalic acid ester that can be used as the plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, and ethyl phthalyl ethyl glycolate.
Examples of commercially available plasticizers include trade name “BENZOFLEX 9-88SG” (Eastman) and trade name “α-methylstyrene” (Mitsubishi Chemical Corporation).

  A plasticizer may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The amount of the plasticizer is preferably 11 parts by weight or more, more preferably 12 parts by weight or more, particularly preferably 13 parts by weight or more, preferably 17 parts by weight or less, based on 100 parts by weight of the acrylic polymer. The amount is preferably 16 parts by weight or less, particularly preferably 15 parts by weight or less. By making the amount of the plasticizer not less than the lower limit value of the range, the adhesiveness of the pressure-sensitive adhesive composition can be increased, and by making the amount not more than the upper limit value of the range, the amount of inorganic particles can be relatively increased. The refractive index of the agent composition can be increased.

[5. Silane coupling agent]
As the silane coupling agent, a silane coupling agent containing an epoxy group is used. Hereinafter, the silane coupling agent containing an epoxy group may be referred to as an “epoxy silane coupling agent” as appropriate. By using an epoxy silane coupling agent in combination with a plasticizer, the adhesiveness of the adhesive composition to glass can be effectively increased. In general, when a silane coupling agent that does not contain an epoxy group is used, the compatibility between the inorganic particles in the pressure-sensitive adhesive composition and components other than the inorganic particles is low, and the pressure-sensitive adhesive composition is gelled or clouded. Could occur. On the other hand, by using an epoxy-based silane coupling agent, the compatibility between the inorganic particles in the pressure-sensitive adhesive composition and components other than the inorganic particles can be increased. It can be suppressed and high transparency can be obtained.

  As the epoxy-based silane coupling agent, a silane coupling agent having one epoxy group in one molecule may be used, or a silane coupling agent having two or more epoxy groups in one molecule may be used. Good. In addition, an aliphatic epoxy silane coupling agent containing an aliphatic epoxy group having an epoxy group in the aliphatic chain may be used, and an alicyclic containing an alicyclic epoxy group having an epoxy group in the alicyclic structure Epoxy silane coupling agents may be used.

  Examples of epoxy silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxy Aliphatic epoxy silane coupling agents such as silane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethyldiethoxysilane; 2- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, 2 -(3,4-epoxycyclohexyl) ethylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldi-n-propoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldiisopropoxysilane, 2- (3,4-D Xylcyclohexyl) ethyldimethylmethoxysilane, 2- (3,4-epoxycyclohexyl) ethyldimethylethoxysilane, 2- (3,4-epoxycyclohexyl) ethyldimethyl n-propoxysilane, 2- (3,4-epoxycyclohexyl) Ethyldimethylisopropoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri-n-propoxy Silane, 2- (3,4-epoxycyclohexyl) ethyltriisopropoxysilane, 2- (3,4-epoxycyclohexyl) ethylethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylethyldiethoxysilane 2- (3,4-epoxycyclohexyl) propyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) propylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) propyltriethoxysilane, 2- ( And alicyclic epoxy-based silane coupling agents such as 3,4-epoxycyclohexyl) propylmethyldiethoxysilane; 3- (NN-glycidyl) aminopropyltrimethoxysilane; and the like.

  Among these, an alicyclic epoxy-based silane coupling agent is preferable because the adhesiveness of the pressure-sensitive adhesive composition can be effectively increased, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane are more preferred, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane is more preferred. Particularly preferred. Moreover, an epoxy-type silane coupling agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the epoxy silane coupling agent is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, preferably 10 parts by weight or less, more preferably 8 parts by weight, based on 100 parts by weight of the acrylic polymer. Part or less, particularly preferably 6 parts by weight or less. By increasing the amount of the epoxy-based silane coupling agent to the lower limit value or more of the above range, it is possible to increase the adhesiveness of the pressure-sensitive adhesive composition, increase the compatibility between the inorganic particles and components other than the inorganic particles, By making it below the upper limit of the range, the amount of inorganic particles can be relatively increased to increase the refractive index of the pressure-sensitive adhesive composition.

[6. Arbitrary ingredients]
The pressure-sensitive adhesive composition may contain optional components other than the above-described acrylic polymer, inorganic particles, plasticizer, and epoxy-based silane coupling agent as necessary.

  As an arbitrary component, a crosslinking agent is mentioned, for example. By using a cross-linking agent, it is possible to cross-link between the acrylic polymers and to impart durability to the adhesive layer as a certain degree of hardness.

  Examples of the crosslinking agent include chemical crosslinking such as isocyanate crosslinking agent, epoxy crosslinking agent, aziridine crosslinking agent, melamine crosslinking agent, aldehyde crosslinking agent, amine crosslinking agent, and metal chelate crosslinking agent. A crosslinking agent capable of forming physical crosslinking, such as a polyfunctional acrylate-based crosslinking agent. Among these, a crosslinking agent that can react with a hydroxyl group is preferable, and an isocyanate-based crosslinking agent and a metal chelate-based crosslinking agent are more preferable. Furthermore, an isocyanate-based crosslinking agent is particularly preferable in terms of improving the adhesiveness between the base material and the adhesive layer and the reactivity with the acrylic polymer.

  Examples of the isocyanate crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylylene diisocyanate, hexamethylene diisocyanate, Diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate; these polyisocyanate compounds and trimethylol Adducts with polyol compounds such as propane; Burettes of these polyisocyanate compounds; Isocyanurates of these polyisocyanate compounds Etc. The.

  Examples of the metal chelate-based crosslinking agent include acetylacetone or acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium, and zirconium. It is done.

  A crosslinking agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the crosslinking agent is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, particularly preferably 0.03 parts by weight or more, preferably 100 parts by weight or more based on the acrylic polymer. It is 20 parts by weight or less, more preferably 15 parts by weight or less, and particularly preferably 10 parts by weight or less. When the amount of the crosslinking agent is not less than the lower limit value of the above range, the cohesive force can be increased and the durability can be effectively increased, and when it is not more than the upper limit value, the flexibility and tackiness can be easily improved.

  Moreover, as an arbitrary component, a solvent is mentioned, for example. Usually, before forming the adhesive layer, the adhesive composition is a fluid composition containing a solvent. Examples of the solvent include the same organic solvents that can be used in the production of the reactive modified metal oxide particles. Moreover, a solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  As a result of manufacturing by a manufacturing method using a solvent, or as a result of purchasing a commercially available product, the above-mentioned acrylic polymer, inorganic particles, plasticizer, epoxy silane coupling agent, and optional components are contained in a solvent. It may be obtained as a solution or suspension dissolved or dispersed therein. In that case, you may mix | blend the solvent contained in them as it is, and may use it as a part or all of the solvent as a component of an adhesive composition.

  The amount of the solvent in the pressure-sensitive adhesive composition is preferably 50 parts by weight or more, more preferably 100 parts by weight or more, preferably 300 parts by weight or less, based on 100 parts by weight of the total solid content of the pressure-sensitive adhesive composition. The amount is preferably 250 parts by weight or less. Here, the solid content of a certain liquid refers to a substance remaining after the liquid is dried.

  Furthermore, as an arbitrary component, a light-diffusion particle is mentioned, for example. As the light diffusing particles, particles of an organic material are preferable. Examples of organic materials include silicone resins, acrylic resins, and polystyrene resins. The volume average particle diameter of the light diffusing particles is preferably 0.2 μm or more, more preferably 0.5 μm or more, preferably 5 μm or less, more preferably 3 μm or less.

  As an example of the commercially available organic light diffusing particles made of silicone resin, the trade name “XC-99” (manufactured by Momentive Performance Materials, volume average particle diameter 0.7 μm) can be mentioned. Moreover, as an example of the commercially available organic type light-diffusion particle | grains which use an acrylic resin as a material, brand name "MP series" (the Soken Chemical Co., Ltd. make, volume average particle diameter of 0.8 micrometer) can be mentioned. Furthermore, as an example of the commercially available organic light diffusing particles made of polystyrene resin, the trade name “SX series” (manufactured by Soken Chemical Co., Ltd., volume average particle diameter 3.5 μm) can be mentioned.

  The volume concentration V of the light diffusing particles is preferably 3% or more, more preferably 4% or more, particularly preferably 5% or more, preferably 35% or less, more preferably, with the entire volume of the adhesive layer being 100%. 30% or less, particularly preferably 25% or less. Light diffusion can be increased by setting the volume concentration V of the light diffusing particles to be equal to or higher than the lower limit value of the range, and compatibility between the acrylic polymer and the light diffusing particles is improved by setting the volume concentration V to be lower than the upper limit value of the range. Thus, the dispersibility of the light diffusing particles can be improved.

  Optional components include, for example, antistatic agents; acrylic adhesives other than those described above; adhesives other than acrylic adhesives; urethane resins, rosins, rosin esters, hydrogenated rosin esters, phenol resins, aromatics Tackifiers such as modified terpene resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins, xylene resins; colorants; fillers; anti-aging agents; ultraviolet absorbers; functional dyes; And compounds capable of causing coloration or discoloration upon irradiation. Furthermore, the pressure-sensitive adhesive composition may contain a small amount of impurities contained in the raw material for producing the constituent components of the pressure-sensitive adhesive composition. The amount of these optional components can be appropriately set so as to obtain desired physical properties.

[7. Physical properties of pressure-sensitive adhesive composition]
The pressure-sensitive adhesive composition described above has a high refractive index. The specific refractive index of the pressure-sensitive adhesive composition is preferably 1.53 or more, more preferably 1.58 or more, and preferably 2.00 or less in a cured state such as a state contained in the pressure-sensitive adhesive layer. It is. Due to the high refractive index of the pressure-sensitive adhesive composition, when the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is bonded to the light emitting surface of the surface light emitter, the light extraction efficiency from the surface light emitter is effectively reduced. Can be improved. The refractive index can be measured with an ellipsometer (M-2000 manufactured by JA Woollam Japan Co., Ltd.).

  The pressure-sensitive adhesive composition described above has high tackiness. Therefore, the pressure-sensitive adhesive composition can be adhered to a surface such as a glass surface or a resin surface with high adhesive force.

[8. Optical laminate]
By using the above-mentioned pressure-sensitive adhesive composition, an optical laminate is obtained. This optical layered body includes a base material and an adhesive layer containing the adhesive composition formed on the base material. This optical layered body is used by bonding the surface of the pressure-sensitive adhesive layer opposite to the substrate to the light emitting surface of the surface light emitter. In this case, since the pressure-sensitive adhesive composition contained in the pressure-sensitive adhesive layer has high adhesiveness, the optical laminate is difficult to peel off from the light emitting surface. In general, the light emitting surface of the surface light emitter is formed of a material having a high refractive index. However, since the refractive index of the pressure sensitive adhesive composition contained in the adhesive layer is high, the interface between the surface light emitter and the adhesive layer (that is, light emission). The light extraction efficiency from the surface light emitter can be increased.

[8.1. Base material〕
As the substrate, a film is usually used. Although it does not specifically limit as a material which comprises this base material, Since it is stuck and used on the light emission surface of a surface light-emitting body, the material which has transparency normally is used. Among them, it is preferable to use a transparent resin as the base material. That the transparent resin is “transparent” means having a light transmittance suitable for use as an optical member. In this embodiment, the members (adhesive layer, base material, and optional layer) constituting the optical layered body are usually provided so as to have a total light transmittance of 80% or more as the entire optical layered body.

  As the transparent resin, a thermoplastic resin is preferable. As the thermoplastic resin, a resin containing a polymer having thermoplasticity can be used. Examples of the thermoplastic polymer include polyester, polyacrylate, and cycloolefin polymer. Specific examples of the polymer include polyesters such as polyethylene naphthalate, polyethylene terephthalate, boribylene terephthalate, polyethylene terephthalate / isophthalate copolymer; polyolefins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride, polyfluoride, and the like. Polyfluorinated ethylenes such as vinylidene fluoride and polyfluorinated ethylene; polyamides such as nylon 6, nylon 6,6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer Polymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose polymers such as cellulose triacetate and cellophane; polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, poly Acrylic polymer butyl acrylic acid, and the like; polystyrene; polycarbonates; polyarylates; can be mentioned polyimide. Of these, cycloolefin polymers and polyesters are preferred. Examples of the substrate made of a resin containing a cycloolefin polymer include “Zeonor film” manufactured by Nippon Zeon. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  When the base material is the outermost surface of the surface light source device, the base material preferably has high scratch resistance. Specifically, the resin as the material of the base material is preferably one having a pencil hardness of HB or higher when a 7 μm-thick layer is formed on the substrate using the resin. Is more preferable, and more than 2H is more preferable.

  Although the thickness of a base material is not specifically limited, Usually, they are 50 micrometers-100 micrometers.

  The refractive index n3 of the substrate is usually 1.59 or more, preferably 1.63 or more.

  The difference between the refractive index n3 of the substrate and the refractive index n2 of the adhesive layer is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less. By setting the difference in refractive index within the above range, loss at the interface can be reduced, and light extraction efficiency can be further increased.

  Further, the base material may be a single-layer body having only one layer or a multilayer body having two or more layers.

[8.2. Adhesive layer)
The pressure-sensitive adhesive layer is a layer containing a pressure-sensitive adhesive composition, and can be formed by applying the pressure-sensitive adhesive composition onto a substrate, drying and curing. When there is a possibility that the substrate deteriorates due to the solvent, heat or active energy rays used at the time of forming the adhesive layer, the adhesive layer is formed on the separator using the adhesive composition, and then the adhesive layer is used as the substrate. It may be pasted. Examples of the separator include a release sheet coated with silicone or the like to give release properties.

  When the pressure-sensitive adhesive composition is applied, the pressure-sensitive adhesive composition may be diluted with a solvent and adjusted to a viscosity suitable for coating. As the dilution concentration, the solid content concentration is preferably 5% by weight or more, more preferably 10% by weight or more, particularly preferably 20% by weight or more, preferably 90% by weight or less, more preferably 80% by weight or less, Especially preferably, it is 75 weight% or less. As the solvent, a solvent capable of dissolving the acrylic polymer can be used. Specific examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic solvents such as toluene and xylene; methanol , Alcohol solvents such as ethanol and propyl alcohol. Among these, ethyl acetate and methyl ethyl ketone are preferable from the viewpoints of solubility, drying property, and price.

  When applied, the viscosity of the pressure-sensitive adhesive composition at 25 ° C. is preferably 20,000 mPa · s or less, particularly preferably 18,000 mPa · s or less, and further preferably 15,000 mPa · s or less. The lower limit of the viscosity is usually 100 mPa · s. Thus, by making a viscosity low, it becomes possible to suppress a coating stripe and can perform coating easily. The viscosity can be measured according to the 4.5.3 rotational viscoclock method of JIS K5400 (1990).

  As a coating method of the pressure-sensitive adhesive composition, a coating method such as a roll coating method, a die coating method, a gravure coating method, a comma coating method, or a screen printing method can be used.

  After coating the pressure-sensitive adhesive composition, the layer of the pressure-sensitive adhesive composition formed by coating is dried. Usually, the layer of the pressure-sensitive adhesive composition is cured by drying to obtain a desired pressure-sensitive adhesive layer. Drying is usually performed by heat drying. Specific drying conditions can be arbitrarily set within a range in which a desired adhesive layer can be obtained. The drying temperature is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, further preferably 65 ° C. or higher, particularly preferably 70 ° C. or higher, preferably 250 ° C. or lower, more preferably 150 ° C. or lower, still more preferably 120 ° C. It is 95 degrees C or less especially preferably. The drying time is preferably 10 seconds to 10 minutes.

Moreover, the formation method of the adhesion layer may include the arbitrary processes further combining with the process mentioned above.
For example, when the pressure-sensitive adhesive composition contains a crosslinking agent, it is preferable to perform an aging treatment after forming the pressure-sensitive adhesive layer. Such an aging treatment can balance the adhesive properties of the adhesive layer. As conditions for aging, the temperature is usually from room temperature to 70 ° C., and the time is usually from 1 day to 30 days. As a specific example, the reaction may be performed at 23 ° C. for 1 day to 20 days, 23 ° C. for 3 to 10 days, and 40 ° C. for 1 day to 7 days. In the present application, the layer before the aging treatment and the layer after the aging treatment are referred to as “adhesive layer” without distinction.

  The thickness of the adhesive layer is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, preferably 500 μm or less, more preferably 300 μm or less, and particularly preferably 250 μm or less.

  Since the adhesive layer contains the adhesive composition described above, it has a high refractive index n2. The specific refractive index n2 of the adhesive layer is preferably 1.53 or more, more preferably 1.58 or more, and preferably 2.00 or less. Since the refractive index n2 of the pressure-sensitive adhesive layer is thus high, the light extraction efficiency can be effectively improved when the optical laminate is provided on the surface light emitter. The refractive index of the adhesive layer can be measured with an ellipsometer (M-2000 manufactured by JA Woollam Japan Co., Ltd.).

  Since the adhesive layer contains the above-mentioned adhesive composition, it has high adhesiveness. The adhesion strength of the adhesive layer to glass is preferably 0.3 N / 25 mm or more, more preferably 0.5 N / 25 mm or more, and particularly preferably 0.7 N / 25 mm or more. When the adhesive strength of the adhesive layer to glass is not less than the lower limit of the above range, the optical laminate can be hardly peeled off from the light emitting surface. The upper limit of the adhesive strength to glass of the adhesive layer is not particularly limited, but is usually 30 N / 25 mm or less.

The adhesion strength of the adhesive layer to glass can be determined by the following method according to JIS K 6854-1.
The optical laminate is cut into a width of 25 mm and a length of 100 mm to obtain a test piece. The surface of the test piece on the adhesive layer side is pressed and adhered to the flat surface of a glass plate having a smooth flat surface by reciprocating a rubber roller weighing 2 kg twice in an atmosphere of 23 ° C. and 50% relative humidity. To do. Then, it is left for 24 hours under the same atmosphere. Then, with the glass plate fixed, a 90 degree peel test is performed by pulling the test piece in the normal direction of the glass plate, and the force required to peel the test piece from the glass plate is measured as an adhesive force (N / 25 mm). To do. In this measurement, the attaching member is attached to an electric measurement stand (for example, an electric measurement stand MX-500N-L550-E manufactured by Imada Co., Ltd.), and a force gauge (for example, a digital force gauge ZP-20N manufactured by Imada Co., Ltd.) is attached. To do. The 90 degree peel test is performed under the conditions of a peel speed of 20 mm / min and a measurement width of 10 mm at room temperature.

  Since the pressure-sensitive adhesive layer contains the above-mentioned pressure-sensitive adhesive composition, it has high transparency. The total light transmittance of the adhesive layer is preferably 80% or more, more preferably 85% or more. The measurement of the total light transmittance can be performed according to JIS K 7136.

[8.3. (Uneven structure layer)
The optical layered body preferably includes a concavo-convex structure layer on the side opposite to the adhesive layer of the substrate. By providing the concavo-convex structure layer, light emitted from the light emitting surface of the surface light emitter can be taken out particularly efficiently. In this case, the concavo-convex structure layer usually has an exposed surface exposed to the outside on the side opposite to the substrate, and this exposed surface has a concavo-convex structure.

  The concavo-convex structure layer preferably has a plurality of concave portions including inclined surfaces and a flat portion adjacent to the concave portions. Here, since the said recessed part is a part comparatively depressed compared with a flat part, it becomes a recessed part, and since the flat part protrudes relatively compared with a recessed part, it corresponds to a convex part. The concavo-convex structure layer is formed by the concavo-convex structure including such concave portions and convex portions.

  In a preferred embodiment, the concavo-convex structure layer includes a plurality of concave portions including four inclined surfaces and a flat portion positioned around the concave portion. Here, the “slope” is a surface that forms an angle that is not parallel to the exposed surface (outermost surface) of the concavo-convex structure layer. On the other hand, the surface on the flat portion is a flat surface parallel to the exposed surface. Each of the plurality of recesses is a regular quadrangular pyramid-shaped depression, and the depressions are arranged at a specific interval. Usually, the four slopes constituting the recess have the same shape, and the base of the regular quadrangular pyramid forms a square.

  Each concave part can usually have a base length of 1 μm to 200 μm, preferably 2 μm to 100 μm. The depth of each recessed part can be normally 1 micrometer-50 micrometers, Preferably it is 2 micrometers-40 micrometers.

  In a preferred embodiment, the recesses are continuously arranged along two orthogonal in-plane directions X and Y at a constant interval. And in the said in-plane direction X and Y, the part which hits the clearance gap between adjacent recessed parts comprises the flat part. Therefore, the concavo-convex structure layer has concave portions and flat portions alternately in the in-plane directions X and Y parallel to the exposed surface. Here, of the two in-plane directions X and Y, one in-plane direction X is parallel to the two bases. In the in-plane direction X, the plurality of recesses are aligned at a constant interval. Of the two in-plane directions X and Y, the other in-plane direction Y is parallel to the other two bases. In the in-plane direction Y, the plurality of recesses are aligned at a constant interval. Here, the flat portion, which is a portion corresponding to the gap, can usually have a width dimension of 0.1 μm to 50 μm.

  The angle formed by the four slopes constituting each of the recesses with the flat portion (and thus the light emitting surface) is preferably 10 ° or more, more preferably 20 ° or more, and preferably 170 ° or less, more preferably 160 ° or less. . In particular, when the shape of the recess is a quadrangular pyramid, the apex angle is preferably 30 ° to 120 °.

  Further, on the exposed surface, the distances in the thickness direction between the bottoms of the adjacent concave portions and the tips of the convex portions may be uneven within a predetermined range, or may be even. Here, the bottom of the concave portion refers to the most depressed portion in each of the concave portions, and refers to the portion where the distance to the base material in the thickness direction is the shortest. Moreover, the front-end | tip of a convex part points out the part most projected in each convex part, and points out the part where the distance to the base material in the thickness direction becomes the longest.

  You may adjust the ratio (henceforth a "flat part ratio") of the area which a flat part occupies with respect to the sum total of the area which a flat part occupies, and the area which a recessed part occupies. Specifically, by setting the flat portion ratio to 10% to 75%, it is possible to realize good light extraction efficiency and increase the mechanical strength of the concavo-convex structure layer.

  In another preferred embodiment, the concavo-convex structure layer has a row of prisms formed on the surface opposite to the substrate. This row-shaped prism includes a plurality of unit prisms as convex portions extending in a direction parallel to the exposed surface (outermost surface) of the concavo-convex structure layer. Normally, these unit prisms all extend in the same direction. Further, these unit prisms may be formed in a gap, but are usually formed side by side without a gap. In addition, the shape of a cross section obtained by cutting the unit prism in a plane perpendicular to the direction in which the unit prism extends is usually a triangle, and preferably an isosceles triangle. However, when the prism is transferred from the mold, the tip of the prism may be rounded. However, in the prism in this specification, the tip of the unit prism is flattened or rounded. including. By flattening or rounding the tip of the outermost unit prism, there is an effect of enhancing the scratch resistance.

  The apex angle of the unit prism is preferably 10 ° or more, more preferably 20 ° or more, particularly preferably 30 ° or more, preferably 80 ° or less, more preferably 70 ° or less, and particularly preferably 65 ° or less. It is. By setting the apex angle of the unit prism to be equal to or higher than the lower limit value of the above range, the prism can be prevented from being damaged. When the tip of the unit prism is flattened or rounded, the apex angle of the unit prism indicates an angle at which two inclined surfaces of the unit prism intersect.

  The dimensions of the unit prism can be arbitrarily set as long as the effects of the present invention are not significantly impaired. For example, the unit prism pitch is preferably 1 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, preferably 500 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm or less. The height (or depth) of the unit prism is preferably 1 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, preferably 500 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm or less. is there. By setting the dimensions of the unit prism in such a range, the light extraction efficiency can be increased and the production of the concavo-convex structure layer can be facilitated.

  The uneven structure layer may have a multilayer structure including a plurality of layers, or may have a single layer structure including a single layer. The concavo-convex structure layer can usually be formed of a transparent resin. The transparent resin is not particularly limited, and various resins that can form a transparent layer can be used. Examples thereof include a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, and an electron beam curable resin. Among them, since the thermoplastic resin is easily deformed by heat, and the ultraviolet curable resin is highly curable and efficient, the concavo-convex structure layer can be efficiently formed.

  Examples of the thermoplastic resin include polyester-based, polyacrylate-based, and cycloolefin polymer-based resins. Examples of the ultraviolet curable resin include epoxy resins, acrylic resins, urethane resins, ene / thiol resins, and isocyanate resins. Among these resins, those containing a polymer having a plurality of polymerizable functional groups are preferable. These resins may be used alone or in combination of two or more at any ratio.

  Furthermore, the resin forming the concavo-convex structure layer may contain an arbitrary component as necessary. Optional components include, for example, degradation inhibitors such as phenols and amines; antistatic agents such as surfactants and siloxanes; light-proofing agents such as triazoles and 2-hydroxybenzophenone; light diffusion particles; Is mentioned. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  In particular, the resin forming the concavo-convex structure layer preferably contains light diffusing particles. As the light diffusing particles, for example, particles selected from the range described as the light diffusing particles that the pressure-sensitive adhesive composition can contain can be used. By using the concavo-convex structure layer containing light diffusing particles, the light extraction efficiency can be effectively improved.

  The amount of light diffusing particles in the concavo-convex structure layer is preferably 1% by weight or more, more preferably 3% by weight or more, particularly preferably 5% by weight or more, preferably 50% by weight or less, more preferably 30% by weight or less. Particularly preferably, it is 20% by weight or less. By keeping the amount of the light diffusing particles in the above range, the light extraction efficiency can be effectively improved.

  Especially, as a material which comprises a concavo-convex structure layer, the material with high hardness at the time of hardening is preferable from a viewpoint that it is easy to form a concavo-convex structure and to obtain the abrasion resistance of a concavo-convex structure. Specifically, when a resin layer having a film thickness of 7 μm is formed on a substrate without a concavo-convex structure, a material having a pencil hardness of HB or higher is preferable, a material of H or higher is more preferable, and 2H or higher The material which becomes is particularly preferred. In the case of providing such a concavo-convex structure layer, the substrate is used to some extent in order to facilitate the handling of the concavo-convex structure layer and the concavo-convex structure layer after forming the concavo-convex structure layer. That which has the flexibility of this is preferable. By combining the flexible base material and the hard concavo-convex structure layer in this way, an optical laminate having a concavo-convex structure that is easy to handle and excellent in durability can be obtained. As a result, a high-performance optical laminate can be obtained. can get.

  Such a combination of the base material and the concavo-convex structure layer can be obtained by appropriately selecting the transparent resin exemplified above as the resin constituting each material. As a specific example, an ultraviolet curable resin such as acrylate is used as the transparent resin constituting the concavo-convex structure layer, while an alicyclic olefin polymer film (for example, Nippon Zeon Co., Ltd.) is used as the transparent resin constituting the substrate. It is preferable to use a ZEONOR film or a polyester film.

  A mode in which the refractive index of the concavo-convex structure layer and the refractive index of the substrate are as close as possible is preferable. In this case, the refractive index difference between the uneven structure layer and the substrate is preferably within 0.1, and more preferably within 0.05.

The thickness of the concavo-convex structure layer is not particularly limited, but is preferably 1 μm to 70 μm.
The thickness of the concavo-convex structure layer is the distance between the surface on the base material side where the concavo-convex structure is not formed and the portion farthest from the base material side surface on the surface opposite to the base material.

  The concavo-convex structure layer can be manufactured, for example, by preparing a mold such as a mold having a desired shape and transferring the mold to a layer of a material forming the concavo-convex structure layer.

[8.4. Any layer)
The optical layered body may further include an arbitrary layer in addition to the base material, the pressure-sensitive adhesive layer, and the uneven structure layer described above. Examples of the optional layer include a light diffusion layer and an ultraviolet absorption layer.

  The light diffusion layer can be formed of a material having light diffusibility. The light diffusion layer can diffuse the light transmitted through the light diffusion layer and change the optical path of the light. Thereby, the optical path length can be lengthened, and the light extraction efficiency can be further increased.

  Examples of the material having light diffusibility include a material containing particles, and an alloy resin that diffuses light by mixing two or more kinds of resins. Among these, from the viewpoint that light diffusibility can be easily adjusted, a material including particles is preferable, and a resin including particles is particularly preferable.

  Examples of the shape of the particles include a spherical shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, a pyramid shape, a conical shape, and a star shape. The particle diameter of the particles is preferably 0.1 μm or more, preferably 10 μm or less, more preferably 5 μm or less. Here, the particle diameter is a 50% particle diameter in an integrated distribution obtained by integrating the volume-based particle amount with the particle diameter as the horizontal axis. The larger the particle size, the larger the proportion of particles required to obtain the desired effect, and the smaller the particle size, the smaller the content. When the particle shape is other than spherical, the diameter of the sphere having the same volume is used as the particle size.

  When the particles are transparent particles and the particles are contained in the transparent resin, the difference between the refractive index of the particles and the refractive index of the transparent resin is preferably 0.05 to 0.5. More preferably, it is 07-0.5. Here, either the particle or the refractive index of the transparent resin may be larger. It is easy to obtain a diffusion effect by making the refractive index difference between the particles and the transparent resin equal to or higher than the lower limit value of the range, and light diffusion becomes excessive by making the refractive index difference equal to or lower than the upper limit value of the range. Can be suppressed.

  The amount of the particles is a volume ratio in the total amount of the layer containing the particles, preferably 1% or more, more preferably 5% or more, and preferably 80% or less, more preferably 50% or less. By setting the content ratio of the particles to the lower limit or higher, desired effects such as a diffusion effect can be obtained. Moreover, by setting it as this upper limit or less, aggregation of particle | grains can be prevented and particle | grains can be disperse | distributed stably.

  The ultraviolet absorbing layer is a layer containing an ultraviolet absorber. Since the surface light source device may use an organic material, the organic material may be easily deteriorated by ultraviolet rays contained in sunlight. Therefore, it is preferable to block ultraviolet rays by providing an ultraviolet absorbing layer. As the ultraviolet absorber, an organic material or an inorganic material may be used. Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, triazine-based, and phenyl salicylate-based ultraviolet absorbers as organic materials. Among these, preferred specific examples include 2,4-dihydroxy-benzophenone, 2-hydroxy-4-methoxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2- (2'-hydroxy-5-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-ditertiarybutylphenyl) benzotriazole, 2,4-bis "2-hydroxy-4-butoxyphenyl ] -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, phenyl salicylate, p-octylphenyl salicylate, p-tertiarybutylphenyl salicylate, etc. Inorganic Examples of the ultraviolet absorber made of the material include titanium dioxide and zinc oxide. Like cerium oxide. Among them, as the ultraviolet absorber, it is preferable to use an inorganic material. UV absorbing agents may be used one kind, or two or more may be used.

  The ultraviolet absorbing layer may contain a binder in order to hold the ultraviolet absorber. As the binder, it is preferable to use a material capable of holding the ultraviolet absorber in the ultraviolet absorbing layer without significantly impairing the effects of the present invention, and a resin is usually used. Examples of resins that can be used as the binder include polyester resins, epoxy resins, acrylic resins, and fluorine resins. Moreover, a binder may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The thickness of the ultraviolet absorbing layer is usually 1 μm or more, preferably 10 μm or more, more preferably 100 μm or more, and usually 10,000 μm or less, preferably 5000 μm or less, more preferably 3000 μm or less. The position where the ultraviolet absorbing layer is provided is not particularly limited.

[9. Surface light source device]
The optical layered body described above is used by sticking an adhesive layer on the light emitting surface of a surface light emitter. Thus, a surface light source device is obtained by providing an optical laminated body on the light emission surface of a surface light-emitting body by sticking an adhesion layer.

  This surface light source device includes a surface light emitter having a light emitting surface and the optical laminate, and the adhesive layer is stuck on the light emitting surface. Therefore, the light generated inside the surface light emitter is extracted through the light emitting surface, the adhesive layer, and the base material. Since the adhesive layer has a high refractive index, the difference in refractive index between the light emitting surface and the adhesive layer is small. Furthermore, the adhesive layer has high transparency. Therefore, in this surface light source device, it is possible to efficiently extract light through the optical laminate. In addition, since the adhesive layer has high adhesiveness, the optical laminate is difficult to peel off from the light emitting surface and is excellent in handleability.

  As the surface light emitter, a surface light emitter including an organic EL element can be used. As a material constituting the light emitting surface of the surface light emitter, glass is usually used. The refractive index n1 of the material constituting such a light emitting surface is preferably 1.50 or more, more preferably 1.51 or more, still more preferably 1.53 or more, and usually 2.00 or less.

  In addition, the adhesive layer can be suitably used in a see-through type surface light source device in which the other side of the surface light emitter can be looked over by making the electrode of the organic EL element transparent because of its high transparency.

  The method of manufacturing the surface light source device is not particularly limited. For example, the surface of the optical laminate on the adhesive layer side is attached to the glass light-emitting surface of the organic EL light-emitting body, and the uneven structure layer is appropriately formed as necessary. It can manufacture by sticking each layer. Here, the “glass-made light emitting surface” is a light emitting surface of a light-emitting body having a glass layer as the outermost layer that emits light.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.
In the following description, “parts” and “%” representing amounts are based on weight unless otherwise specified.

  In the following description, the weight average molecular weight, number average molecular weight, dispersity, and glass transition temperature of the acrylic polymer were measured according to the methods described above. The viscosity was measured according to the 4.5.3 rotational viscometer method of JIS K5400 (1990).

[Evaluation method]
[Method for evaluating appearance of pressure-sensitive adhesive composition]
The appearance of the pressure-sensitive adhesive composition was visually observed. When the pressure-sensitive adhesive composition was transparent without white turbidity and gelation, it was judged as “good”. Further, when the pressure-sensitive adhesive composition was clouded or gelled, it was determined as “bad”.

[Measurement method of refractive index of adhesive layer]
The release sheet on one side was peeled off from the adhesive layer of the double-sided adhesive sheet, and the refractive index of the adhesive layer was measured using an ellipsometer (“M-2000” manufactured by JA Woollam Japan).

[Measurement method of total light transmittance of optical laminate]
The total light transmittance of the optical laminated body was measured according to JIS K7361-1.

[Measurement method of adhesive strength of adhesive layer]
The optical laminate was cut into a width of 25 mm and a length of 100 mm to obtain a test piece. The surface of the test piece on the pressure-sensitive adhesive layer side is a flat surface of a glass plate having a smooth plane (thickness 0.7 mm, refractive index 1.53), and the weight is 2 kg under an atmosphere of 23 ° C. and a relative humidity of 50%. The rubber roller was reciprocated twice to apply pressure. Then, it was left under the same atmosphere for 24 hours. Then, with the glass plate fixed, a 90 degree peel test is performed by pulling the test piece in the normal direction of the glass plate, and the force required to peel the test piece from the glass plate is measured as an adhesive force (N / 25 mm). did. The 90 degree peel test was performed at room temperature under the conditions of a peel speed of 20 mm / min and a measurement width of 10 mm.

[Production Example 1. Production of acrylic polymer]
A reactor equipped with a thermometer, a stirrer, a dropping funnel and a reflux condenser was charged with 28 parts of methyl ethyl ketone and 8 parts of toluene, and the temperature was raised while stirring. After reaching 90 ° C., 70 parts of benzyl acrylate, 2-hydroxy A mixture in which 0.16 part of azobisisobutyronitrile (AIBN) as a polymerization initiator was dissolved in 15 parts of ethyl acrylate and 15 parts of butyl acrylate was dropped over 2 hours. Further, during the polymerization, while adding a polymerization catalyst solution in which 0.06 part of AIBN was dissolved in 2 parts of ethyl acetate, polymerization was continued for 7 hours, and an acrylic polymer solution (solid content concentration 65.1%, viscosity 1300 mPas). S (25 ° C.) was obtained. The obtained acrylic polymer had a weight average molecular weight of 105,000, a number average molecular weight of 36,000, a dispersity of 2.92, and a glass transition temperature of −8.3 ° C.

[Example 1]
[1-1. Production of pressure-sensitive adhesive composition)
A dispersion (“SZR-K” manufactured by Sakai Chemical Industry Co., Ltd.) containing zirconium oxide particles was prepared. The concentration of the zirconium oxide particles in this dispersion was 30% by weight, the volume average particle diameter of the zirconium oxide particles was 4 nm, and the solvent was a mixed solvent of methyl ethyl ketone and methanol (methyl ethyl ketone / methanol = 90% / 10%). It was. The dispersion was diluted by adding methyl ethyl ketone to adjust the concentration of the zirconium oxide particles to 20% by weight, and then stirred for 30 minutes using a homogenizer.

  The stirred dispersion containing the zirconium oxide particles was 82 parts in terms of solid content. To the dispersion containing the zirconium oxide particles, 100 parts of the acrylic polymer solution produced in Production Example 1 in solid content and dipropylene glycol dibenzoate ("BENZOFLEX 9-88SG" manufactured by Eastman); (Less than 0 °) 17 parts and 3 parts of an epoxy silane coupling agent (“KBM-303” manufactured by Shin-Etsu Silicone Co., Ltd.) represented by the following formula (2) are added and stirred for 30 minutes using a homogenizer. A pressure-sensitive adhesive composition was obtained. The appearance of this pressure-sensitive adhesive composition was evaluated by the method described above.

[1-2. Production of double-sided PSA sheet with adhesive layer]
The pressure-sensitive adhesive composition was applied to a polyester release sheet so that the film thickness after drying was 20 μm, and dried at 100 ° C. for 4 minutes to form a pressure-sensitive adhesive layer. Thereby, a multilayered product having a two-layer structure having a layer structure of (release sheet) / (adhesive layer) was obtained. Thereafter, another polyester-based release sheet is bonded to the surface on the pressure-sensitive adhesive layer side of the multilayer, and the three-layer structure has a layer structure of (release sheet) / (adhesive layer) / (release sheet). A multilayer was obtained. This multi-layered product was aged at 40 ° C. for 10 days to obtain a double-sided PSA sheet. Using this double-sided PSA sheet, the refractive index of the PSA layer was measured by the method described above.

[1-3. (Manufacture of optical laminate)
The release sheet on one side was peeled off from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to expose the pressure-sensitive adhesive layer. A 100 μm thick polyethylene terephthalate film (PET film; refractive index = 1.65) was bonded to the exposed surface of the adhesive layer. Thereafter, the release sheet on the other surface of the pressure-sensitive adhesive layer was peeled off to obtain an optical laminate having a layer structure of (pressure-sensitive adhesive layer) / (PET film). Using this optical laminate, the total light transmittance of the optical laminate and the adhesive strength of the adhesive layer were measured by the method described above.

[Example 2]
Production and evaluation of the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer, and the optical laminate were performed in the same manner as in Example 1 except that the amount of the dispersion containing zirconium oxide particles was changed to 100 parts in terms of solid content.

[Example 3]
The pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer, and the optical laminate were the same as in Example 1 except that the amount of the dispersion containing zirconium oxide particles was changed to 100 parts by solid content and the amount of the plasticizer was changed to 11 parts. The body was manufactured and evaluated.

[Example 4]
Except having changed the quantity of the plasticizer into 8 parts, it carried out similarly to Example 1, and manufactured and evaluated the adhesive composition, the adhesion layer, and the optical laminated body.

[Comparative Example 1]
A pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and an optical laminate were produced and evaluated in the same manner as in Example 1 except that no plasticizer was used.

[Comparative Example 2]
The pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer, and the optical lamination were the same as in Example 1 except that the amount of the dispersion containing zirconium oxide particles was changed to 100 parts in terms of solid content and that no plasticizer was used. The body was manufactured and evaluated.

[Comparative Example 3]
Instead of the dispersion containing zirconium oxide particles, a dispersion of reactive modified metal oxide particles containing ZrO ₂ ("NANON5 ZR-010" manufactured by Solar) was used in a solid content of 67 parts. In this dispersion of reactive modified metal oxide particles, the solvent is methyl ethyl ketone, the concentration of the particles is 30%, and the organic substance having a reactive functional group that modifies the particle surface is an isocyanate having a polymerizable functional group. The volume average particle diameter of the particles was 17 nm. Except for the above matters, the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer and the optical laminate were produced and evaluated in the same manner as in Example 1.

[Comparative Example 4]
Instead of the dispersion containing zirconium oxide particles, 82 parts of a dispersion of reactive modified metal oxide particles containing ZrO ₂ ("NANON5 ZR-010" manufactured by Solar) was used in solid content. Except for the above matters, the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer and the optical laminate were produced and evaluated in the same manner as in Example 1.

[Comparative Example 5]
As in Example 1, except that 3 parts of a mercapto silane coupling agent (“KBM-803” manufactured by Shin-Etsu Silicone Co., Ltd.) was used as the silane coupling agent instead of the epoxy silane coupling agent. Production and evaluation of the composition, the pressure-sensitive adhesive layer, and the optical laminate were performed.

[Comparative Example 6]
As in Example 1, except that 3 parts of an amino silane coupling agent (“KBM-602” manufactured by Shin-Etsu Silicone Co., Ltd.) was used as the silane coupling agent instead of the epoxy silane coupling agent. Production and evaluation of the composition, the pressure-sensitive adhesive layer, and the optical laminate were performed.

[Comparative Example 7]
As in Example 1, except that 3 parts of an amino silane coupling agent (“KBE-903” manufactured by Shin-Etsu Silicone Co., Ltd.) was used as the silane coupling agent instead of the epoxy silane coupling agent. Production and evaluation of the composition, the pressure-sensitive adhesive layer, and the optical laminate were performed.

[Comparative Example 8]
Production and evaluation of the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer, and the optical laminate were performed in the same manner as in Example 1 except that the amount of the dispersion containing zirconium oxide particles was changed to 40 parts in terms of solid content.

[Comparative Example 9]
Production and evaluation of the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer and the optical laminate were carried out in the same manner as in Example 1 except that the amount of the dispersion containing zirconium oxide particles was changed to 160 parts in terms of solid content.

[result]
The results of Examples and Comparative Examples described above are shown in Table 1 and Table 2 below. In Tables 1 and 2 below, the meanings of the abbreviations are as follows.
BZA: benzyl acrylate as an aromatic ring-containing monomer.
HEA: 2-hydroxyethyl acrylate as a hydroxyl group-containing monomer.
BA: Butyl acrylate as a (meth) acrylic acid alkyl ester monomer.
Mw: weight average molecular weight.
9-88SG: “BENZOFLEX 9-88SG” manufactured by Eastman.
SZR-K: “SZR-K” manufactured by Sakai Chemical Industry Co., Ltd.
NANON5: “NANON5 ZR-010” manufactured by Solar Corporation.

[Consideration]
As can be seen from Table 1 and Table 2 above, in the comparative examples, the results are inferior in refractive index, total light transmittance or adhesive strength, but in Examples, the refractive index, total light transmittance and adhesive strength are low. In any case, excellent results are obtained. From this, it was confirmed that the pressure-sensitive adhesive composition of the present invention can realize a pressure-sensitive adhesive layer having high refractive index, transparency, and pressure-sensitive adhesiveness.

Claims (8)

Including acrylic polymer, inorganic particles, plasticizer and silane coupling agent,
The acrylic polymer is a copolymer of copolymer components including 40% to 93% by weight of an aromatic ring-containing acrylic monomer and 7% to 60% by weight of a hydroxyl group-containing monomer, and the weight average molecular weight thereof is 200,000 or less,
The silane coupling agent contains an epoxy group,
The volume average particle diameter of the inorganic particles is 1 nm or more and 15 nm or less,
The pressure-sensitive adhesive composition for an optical member, wherein the amount of the inorganic particles is from 82 parts by weight to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer.   The pressure-sensitive adhesive composition for an optical member according to claim 1, wherein an amount of the plasticizer is 11 to 17 parts by weight with respect to 100 parts by weight of the acrylic polymer.   The pressure-sensitive adhesive composition for an optical member according to claim 1 or 2, wherein the plasticizer has a melting point of 0 ° C or lower.   The pressure-sensitive adhesive composition for an optical member according to any one of claims 1 to 3, wherein the plasticizer is selected from the group consisting of ester plasticizers.   The pressure-sensitive adhesive composition for an optical member according to any one of claims 1 to 4, wherein the plasticizer is an aromatic ring-containing ester.   The pressure-sensitive adhesive composition for an optical member according to any one of claims 1 to 5, wherein the refractive index is 1.58 or more. A base material, and an adhesive layer formed on the base material,
The optical laminated body in which the said adhesion layer contains the adhesive composition for optical members of any one of Claims 1-6. A surface light emitter having a light emitting surface;
An optical laminate according to claim 7,
A surface light source device in which the adhesive layer is attached to the light emitting surface.