JPWO2018101421A1 - Adhesive composition, laminate using the adhesive composition, method for producing the laminate, and use of the adhesive composition - Google Patents

Abstract

The present invention provides an adhesive for bonding a convex surface of a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a base sheet [II] having a flat surface. An adhesive composition comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more. Related to things.

Description

The present invention relates to an adhesive composition for bonding a convex surface of a base sheet [I] having a convex surface and a flat surface of a base sheet [II] having a flat surface, particularly, prism sheets to each other. It is related with the adhesive composition for bonding together, and the adhesive composition for bonding together a prism sheet and a diffusion sheet.
Moreover, this invention relates to the laminated body using this adhesive composition, the manufacturing method of this laminated body, and use of this adhesive composition.

  Conventionally, ultraviolet curable adhesives, thermosetting adhesives, and the like have been used as adhesives for bonding prism sheets and the like. For example, Patent Document 1 describes “three bond 3042B” as a specific example of an ultraviolet curable adhesive, and “Sankei Epochure and Epochik Co., Ltd. 5: 1 as thermosetting adhesives”. "Mixed with".

Japanese Laid-Open Patent Publication No. 2007-155938

  However, in the technique described in Patent Document 1, when the prism sheet is bonded, the adhesiveness is obtained to some extent, but it is still not satisfactory, and as the technology becomes more advanced in recent years, further adhesion is achieved. Sex is required.

  Furthermore, in the bonding of the prism sheet, high optical characteristics are required from the viewpoint of luminance and color of the display. For example, in a laminated body in which prism sheets are bonded together, it is necessary to bond the prism sheets to each other only with convex portions without filling the concave and convex portions in order to exert the function of “diffusing light”. is there. In this case, when the object over there is viewed through the laminate composed of the prism sheet, the light is diffused and the object over there appears to be doubled, and it has good optical characteristics. . On the other hand, if the adhesive is buried in the concavo-convex portion of the prism sheet, the light diffusibility is lowered.

  Therefore, in the present invention, under such a background, an adhesive for bonding the convex surface of the base sheet [I] having a convex surface and the flat surface of the base sheet [II] having a flat surface is provided. Adhesive composition having excellent properties and optical properties (light diffusibility), laminate using the adhesive composition, method for producing the laminate, and use of the adhesive composition It is intended to provide.

  However, as a result of intensive studies to solve the above-mentioned problems, the present inventors have found that an ethylenically unsaturated monomer having a high viscosity (as a photocurable compound) in an adhesive composition containing a photocurable compound ( The present inventors have found that the above problem can be solved by using A) and completed the present invention.

That is, the present invention relates to the following <1> to <8>.
<1> Adhesive for bonding the convex surface of the base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and the flat surface of the base sheet [II] having a flat surface A composition comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more. , Adhesive composition.
<2> The adhesive composition according to <1>, wherein the ethylenically unsaturated monomer (A) has a molecular weight of 1,000 or less.
<3> The adhesive composition according to <1> or <2>, wherein the ethylenically unsaturated monomer (A) is contained in the photocurable compound in an amount of 20% by weight or more.
<4> The adhesive composition according to any one of <1> to <3>, further comprising a photopolymerization initiator (B).
<5> The base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and the base sheet [II] having a flat surface are any one of <1> to <4>. A laminated body characterized by being laminated through an adhesive comprising the described adhesive composition.
<6> The laminate according to <5>, wherein the base sheet [I] and the base sheet [II] are each a prism sheet or a diffusion sheet.
<7> Using the adhesive composition according to any one of <1> to <4>, a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface. The manufacturing method of a laminated body characterized by including the process of laminating | stacking base material sheet [II] which has, and the process of hardening | curing the said adhesive composition.
<8> An adhesive composition comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more. Use for bonding the convex surface of the base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and the flat surface of the base sheet [II] having a flat surface.

  The adhesive composition of the present invention comprises a convex surface of a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a base sheet [II] having a flat surface. An adhesive composition for bonding, comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more. Therefore, it has very good adhesiveness and also has excellent optical properties (light diffusibility).

  Moreover, the adhesive composition of this invention comes to become further excellent in adhesiveness because the molecular weight of the said ethylenically unsaturated monomer (A) is 1,000 or less.

  Furthermore, the adhesive composition of the present invention is excellent in adhesion at the convex portion of the uneven surface when the ethylenically unsaturated monomer (A) is contained in the photocurable compound in an amount of 20% by weight or more. .

  Further, the adhesive composition of the present invention can further be cured by ultraviolet rays by containing the photopolymerization initiator (B), and is excellent in workability.

  Further, the base sheet [I] and the base sheet [II] are laminated via an adhesive composed of the above-mentioned adhesive composition, whereby the adhesive layer is less peeled and the like is excellent in stability over time. The body comes to be obtained.

  And since the contact point for bonding them decreases depending on the apex angle on the prism sheet or the diffusion sheet, it has been difficult to sufficiently bond them conventionally. The base sheet [I] and the base sheet Even if [II] is a prism sheet or a diffusion sheet, respectively, it is possible to obtain a laminate having excellent temporal stability with little peeling of the adhesive layer and the like by using an adhesive comprising the above adhesive composition. become.

  Using the adhesive composition, an adhesive is produced by a method for producing a laminate comprising a step of laminating a base sheet [I] and a base sheet [II] and a step of curing the adhesive composition. A layered product with less peeling of the layer and the like and excellent stability over time can be obtained.

FIG. 1 is a cross-sectional view showing a preferred embodiment of the laminate of the present invention. FIG. 2 is a schematic exploded perspective view illustrating the laminate shown in FIG. FIG. 3 is a sectional view of the prism sheet 2 and the prism sheet 3 cut along X-X ′ in the exploded perspective view shown in FIG. 2. 4 is a cross-sectional view similar to FIG. 3 except that the prism sheet 2 in the cross-sectional view of FIG. . FIG. 5 is a cross-sectional view showing in more detail the bonding of the diffusion sheet 1 and the prism sheet 2 of the laminate shown in FIG. 6 is a cross-sectional view of the diffusion sheet 1 and the prism sheet 2 cut along X-X ′ in the exploded perspective view shown in FIG. 2 (corresponding to the exploded view of FIG. 5).

  Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

  In the present invention, “(meth) acrylate” is a generic term for acrylate and methacrylate, and “(meth) acryl” is a generic term for acrylic and methacrylic. “Polyfunctional” means having two or more (meth) acryloyl groups in the molecule.

<Adhesive composition>
The adhesive composition of the present invention comprises a convex surface of a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a base sheet [II] having a flat surface. An adhesive composition for bonding, comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more. It is characterized by doing.
Here, the components of the adhesive composition will be described.

[Photocurable compound]
The adhesive composition of the present invention contains a photocurable compound. The content of the photocurable compound in the adhesive composition of the present invention is preferably 1 to 99.5% by weight, more preferably 5 to 99.5% by weight, and still more preferably, from the viewpoint of adhesive strength after curing. Is from 10 to 99% by weight. If the content of the photocurable compound is too low, the hardness after curing tends to be insufficient and the adhesive strength tends to be low. If the content is too high, the adhesive strength tends to decrease due to curing shrinkage.

In the adhesive composition of the present invention, it is important that the photocurable compound contains an ethylenically unsaturated monomer (A).
The ethylenically unsaturated monomer (A) has a viscosity at 25 ° C. of 3,000 mPa · s or more, preferably 4,000 to 30,000 mPa · s, particularly preferably 5,000 to 25,000 mPa · s, More preferably, it is 6,000 to 20,000 mPa · s, and particularly preferably 8,000 to 15,000 mPa · s. If the viscosity is too low, the adhesive composition enters the uneven portions of the prism and the brightness increasing function of the prism sheet tends to be reduced. In addition, when this viscosity is too high, there exists a tendency for the coating property to fall.

  In addition, the viscosity in 25 degreeC of an ethylenically unsaturated monomer (A) can be measured based on JISZ8803 using E-type viscosity meter TPE-100H (made by Toki Sangyo Co., Ltd.).

  The ethylenically unsaturated monomer (A) preferably has a molecular weight of 1,000 or less, more preferably 50 to 900, more preferably 150 in terms of adhesion between the convex surface and the flat surface. More preferably, it is -500. If the molecular weight is too large, the adhesiveness tends to decrease. If the molecular weight is too small, the viscosity cannot be maintained and coating tends to be difficult.

Specific examples of the ethylenically unsaturated monomer (A) include, for example,
2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropyl phthalic acid, 2- (meth) acryloyloxypropyl tetrahydrophthalic acid, 2- ( (Meth) acryloyloxypropylhexahydrophthalic acid, (meth) acryloyloxyethylphthalic acid, (meth) acryloyloxyethyltetrahydrophthalic acid, (meth) acryloyloxyethylhexahydrophthalic acid, (meth) acryloyloxypropylhexahydrophthalic acid (Meth) acrylates having a carboxyl group such as
Acrylates having a hydroxyl group such as 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylate, isocyanuric acid ethylene oxide-modified diacrylate;
(Meth) acrylates having a fluorene structure such as 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorange (meth) acrylate;
(Meth) acrylates having an alkoxylated bisphenol structure, such as proxiated bisphenol A di (meth) acrylate;
(Meth) acrylate having a phosphate group such as 2- (meth) acryloyloxyethyl acid phosphate;
(Meth) acrylates having an isocyanurate structure such as caprolactone-modified tris- (2-acryloxyethyl) isocyanurate;
Dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol (meth) acrylate;
Bifunctional acrylates such as bisphenol A ethylene oxide modified (3.8) adduct di (meth) acrylate, bisphenol A diglycidyl ether acrylic acid adduct, tripentaerythritol acrylate;
Rubber-terminated (meth) acrylates such as polybutadiene-terminated di (meth) acrylate;
Etc.

  Among these, those having an aromatic ring structure are preferable from the viewpoint of adhesion, and in particular, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxypropylphthalic acid, 2-acryloyloxypropyltetrahydrophthalic acid, 2-acryloyloxypropyl. Acrylate having a carboxyl group such as hexahydrophthalic acid, methacryloyloxyethyl phthalic acid, methacryloyloxyethyl tetrahydrophthalic acid, methacryloyloxyethyl hexahydrophthalic acid, methacrylate having a carboxyl group such as methacryloyloxypropylhexahydrophthalic acid are preferred, In particular, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxypropyl phthalic acid, 2-acryloyloxypropyltetra Dorofutaru acid, acrylate having a 2-acryloyloxypropyl hexahydrophthalate carboxyl group, such as phthalic acid are preferred.

  Moreover, the adhesive composition of this invention may contain photocurable compounds other than an ethylenically unsaturated monomer (A).

Such a photocurable compound is used for coating properties, curability, adhesiveness, and the like. For example, it is ethylenic having one ethylenically unsaturated group other than the ethylenically unsaturated monomer (A). An unsaturated compound (hereinafter sometimes referred to as “monofunctional monomer”) or an ethylenically unsaturated compound having two or more ethylenically unsaturated groups (hereinafter referred to as “polyfunctional monomer”). ) And the like.
Moreover, oligomers, such as a urethane (meth) acrylate type compound and an epoxy (meth) acrylate type compound, are mentioned as a photocurable compound.

  In the adhesive composition of the present invention, it is preferable that the ethylenically unsaturated monomer (A) is contained in the photocurable compound in an amount of 20% by weight or more from the viewpoint of optical properties and coatability, and particularly 25% by weight. % Or more, preferably 30% by weight or more. When the content ratio is too low, the optical properties after production of the laminate tend to deteriorate due to the low viscosity. In addition, the upper limit of this content rate is 100 weight%.

[Photopolymerization initiator (B)]
In the adhesive composition of the present invention, it is preferable to further contain a photopolymerization initiator (B) in that it can be cured by irradiation with active energy rays such as ultraviolet rays for a very short time.

  Examples of the photopolymerization initiator (B) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4- Acetophenones such as morpholinophenyl) butanone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl Benzo such as ether Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium Benzophenones such as chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy ) -3, -Thioxanthones such as dimethyl-9H-thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentyl Acylphosphine oxides such as phosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; In addition, as for these photoinitiators (B), only 1 type may be used independently and 2 or more types may be used together.

  Moreover, triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid as an auxiliary for these photopolymerization initiators (B) Ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2 , 4-Diisopropylthioxanthone can also be used in combination.

  Among these photopolymerization initiators (B), benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-hydroxy It is preferable to use 2-methyl-1-phenylpropan-1-one.

  About content of the said photoinitiator (B), it is preferable that it is 0.5-20 weight part with respect to 100 weight part of said photocurable compounds, Especially 0.8-15 weight part, Furthermore, Is preferably 1 to 10 parts by weight. If the content of the photopolymerization initiator (B) is too small, the curability tends to be poor and the physical properties tend to be unstable. If the content is too large, the low molecular weight component increases, the crosslinking density decreases, and water resistance, heat resistance, etc. There is a tendency to decrease.

[(Meth) acrylic resin (C)]
The adhesive composition of the present invention may further contain (meth) acrylic resin (C) (hereinafter sometimes simply referred to as “acrylic resin (C)”) to form a film upon coating. This is preferable.

  The acrylic resin (C) is obtained by polymerizing a monomer component containing a (meth) acrylic monomer, and the (meth) acrylic monomer is used alone or in combination of two or more. It is made.

  The acrylic resin (C) preferably contains a (meth) acrylic acid ester monomer as a polymerization component, and a functional group-containing monomer or other copolymerizable monomer as a copolymerization component, if necessary. You can also.

Examples of such (meth) acrylic acid ester monomers include monomer components that are usually used in acrylic resins. Among them, copolymerization, excellent coating strength, ease of handling, and availability of raw materials In particular, aliphatic (meth) acrylate monomers, typically methyl (meth) acrylate, n-butyl (meth) acrylate, and isobornyl (meth) acrylate are preferably used, and particularly preferably methyl (meth) acrylate. It is.
These (meth) acrylic acid ester monomers can be used alone or in combination of two or more.

  Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an alkoxy group-containing monomer, a phenoxy group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, a nitrogen-containing monomer (however, the amide group-containing monomer, Amino group-containing monomers are excluded.), Glycidyl group-containing monomers, phosphate group-containing monomers, sulfonic acid group-containing monomers, and the like. These may be used alone or in combination of two or more.

  The acrylic resin (C) is preferably a polymer comprising a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms as a polymerization component, particularly methyl ( A polymer containing meth) acrylate as a polymerization component is preferred, a polymer containing methyl metallate as a polymerization component is preferred, and polymethyl methacrylate is more preferred.

The glass transition temperature (Tg) of the acrylic resin (C) is usually 0 to 180 ° C, preferably 15 to 175 ° C, particularly preferably 50 to 130 ° C. If the glass transition temperature is too high, the effect of alleviating the thermal shrinkage of the cured product tends to decrease, and if it is too low, the thermal durability of the cured product tends to decrease.
The measurement of the glass transition temperature is a value measured using a DSC (differential scanning calorimeter).

  The weight average molecular weight of the acrylic resin (C) is usually 10,000 to 500,000, preferably 10,000 to 100,000. If the weight average molecular weight is too large, the coating strength tends to decrease, and if it is too small, the adhesion to a substrate such as a glass substrate or the coating appearance tends to decrease.

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (C) is usually 1 to 4, preferably 1.5 to 2.5.

In addition, said weight average molecular weight and number average molecular weight are based on standard polystyrene molecular weight conversion, a column is added to a high performance liquid chromatography (Nippon Waters Co., Ltd., "Waters2695 (main body)" and "Waters2414 (detector)"). : ShodexGPCKF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / piece, filler material: styrene-divinylbenzene copolymer, filler particle size : 10 μm).

  In addition, the use of a solvent-free acrylic resin that does not substantially contain a solvent as the acrylic resin (C) makes it possible to eliminate environmental measures such as compliance with VOC (volatile organic compound) regulations, and the drying process. It is preferable in terms of improvement of coating property and improvement of coating property to a material weak against heat and solvent.

  As the solventless acrylic resin, an acrylic resin that does not substantially contain a solvent in the resin can be used. As the “acrylic resin substantially free of solvent”, the content of the solvent in the resin is usually 3% by weight or less, preferably 1% by weight or less, particularly preferably 0.5% by weight or less, and more preferably 0%. An acrylic resin that is 2% by weight or less may be mentioned.

  The content of the acrylic resin (C) in the adhesive composition of the present invention is preferably 1 to 50% by weight, more preferably 5 to 40% by weight, and still more preferably, from the viewpoints of adhesive strength and coatability. 10 to 30% by weight. If the content is too small, the curing shrinkage of the adhesive composition cannot be alleviated, and the adhesive strength tends to decrease. If the content is too large, the viscosity tends to be high and coating tends to be difficult.

[Others]
In the adhesive composition of the present invention, in addition to the above components, an antistatic agent, other acrylic adhesives, other adhesives, urethane resin, rosin, rosin ester, as long as the effects of the present invention are not impaired. Hydrogenated rosin ester, phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin and other tackifiers, polyol and other plasticizers, antioxidants, Mixing conventionally known additives such as leveling agents, rheology control agents, colorants, fillers, anti-aging agents, ultraviolet absorbers and functional dyes, and compounds that cause coloration or discoloration upon irradiation with ultraviolet rays or radiation. However, the amount of these additives is preferably 30% by weight or less, particularly preferably 20% by weight or less, based on the whole adhesive composition. .
In addition to the above additives, a small amount of impurities contained in the raw materials for producing the constituent components of the adhesive composition may be contained.

The adhesive composition of the present invention can be obtained by stirring and mixing the above-described constituent components according to a known method.
The adhesive composition of the present invention preferably functions as an adhesive by being cured by irradiation with active energy rays, and can be suitably used as an adhesive for bonding base sheets.

  The adhesive composition of the present invention has a viscosity at 25 ° C. of usually 1 to 35,000 mPa · s, preferably 2 to 30,000 mPa · s, particularly from the viewpoint of applicability to a substrate. Preferably it is 3-25,000 mPa * s. If the viscosity is too low, unevenness tends to occur during application to the substrate, and if it is too high, application to the substrate tends to be difficult.

  The adhesive composition of the present invention can be used as it is when it is applied to a substrate sheet, but it is preferable to adjust the viscosity by diluting with a solvent from the viewpoint of the coating property to the substrate. In coating, the viscosity after viscosity adjustment is preferably in the above range.

  The concentration in the case of containing a solvent is usually 3 to 90% by weight, preferably 5 to 80% by weight, particularly preferably 10 to 70% by weight as the solid content of the adhesive. If the concentration is too low, the leveling property tends to decrease when applied to the substrate, and if it is too high, the viscosity tends to increase, making it difficult to apply.

Examples of such solvents include alcohols such as methanol, ethanol, propanol, n-butanol and i-butanol, ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone and cyclohexanone, cellosolves such as ethyl cellosolve, toluene, xylene and the like. Aromatics, glycol ethers such as propylene glycol monomethyl ether, acetates such as methyl acetate, ethyl acetate, and butyl acetate, diacetone alcohol, and the like. These solvents may be used alone, Two or more kinds may be used in combination.
These solvents are preferably removed by drying after application to the substrate sheet and before curing by irradiation with active energy rays described later.

<Laminated body>
The laminate of the present invention is characterized in that the base sheet [I] and the base sheet [II] are laminated via an adhesive comprising the adhesive composition of the present invention.
The laminate of the present invention obtained by laminating the base sheet [I] and the base sheet [II] using the adhesive comprising the adhesive composition of the present invention has less peeling of the adhesive layer, etc. It is a laminate excellent in stability over time.

  As the base sheet [I], at least one surface of the sheet has a convex surface with a surface roughness Ra of 0.1 to 100 μm, and the convex surface has a plurality of convex portions. The height of may be constant or different. Examples of the convex shape include dots, stripes, and lattices, and a stripe shape is particularly preferable from the viewpoint of both optical properties and adhesiveness.

  The base sheet [I] is a lens sheet in which convex lenses formed in one axial direction are arranged adjacent to each other, a so-called prism sheet, or a diffusion sheet in which irregularities are randomly formed. It is particularly preferred. Examples of the prism sheet include a prism sheet having a pitch of 60 μm, an average unevenness height of 30 μm, and a convex portion having an apex angle of 90 degrees (right angle).

  The measurement of the surface roughness Ra (μm) is in accordance with JIS B 0601 (1982), centerline average roughness. In the case of a prism sheet or a diffusion sheet, the average unevenness height corresponds to this. To do.

  The material and manufacturing method of such a base sheet [I] can take various known aspects. For example, a sheet-shaped resin material extruded from a die is transferred to a concave transfer roller (with a reverse surface of the convex surface formed on the surface) that rotates at substantially the same speed as the extrusion speed of the resin material. It is possible to employ a resin sheet manufacturing method in which pressure is sandwiched between nip roller plates arranged opposite to each other and rotating at the same speed, and the uneven shape on the transfer roller surface is transferred to a resin material.

  Moreover, the manufacturing method of the resin sheet which laminates | stacks the transcription | transfer mold board (stamper) in which the inversion type | mold of the convex part surface is formed on the surface by hot press, and is press-molded by thermal transfer is employable.

  As a resin material used in such a manufacturing method, a thermoplastic resin can be used. For example, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyolefin, acrylic, polystyrene, polycarbonate Polyamide, PET (polyethylene terephthalate), biaxially stretched polyethylene terephthalate, polyethylene naphthalate, polyamideimide, polyimide, aromatic polyamide, cellulose acylate, cellulose triacetate, cellulose acetate propionate, cellulose diacetate, etc. It is done.

  Further, as another manufacturing method, the unevenness on the surface of a concavo-convex roller (inverted type of convex surface is formed on the surface) is transferred and formed on the surface of a transparent film (for example, a film made of the thermoplastic resin). A resin sheet manufacturing method can be employed.

  As another manufacturing method, a thermosetting or UV curable resin layer is formed on the surface of a transparent film (for example, a film made of the above-mentioned thermoplastic resin), and an uneven roller (an inversion type of the convex surface is used). It is possible to adopt a method for producing a resin sheet in which surface irregularities (formed on the surface) are transferred to a resin layer and cured by heat or UV.

  On the other hand, as the base sheet [II], if at least one side of the sheet has a flat surface, the other side may have a convex shape shown in the base sheet [I]. Good. Here, the flat surface means a flat surface having no unevenness, and preferably has a surface roughness Ra of less than 0.1 μm. The lower limit value of the surface roughness Ra is usually 0.001 μm.

  Examples of such a base sheet [II] include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyolefin, acrylic, polystyrene, polycarbonate, polyamide, PET (polyethylene terephthalate), and PEN (polyethylene). Naphthalate), polymethyl methacrylate, polyether ether ketone, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, biaxially stretched polyethylene terephthalate, polyamideimide, polyimide, aromatic polyamide, cellulose acylate, cellulose triacetate, cellulose A known transparent film made of a material such as acetate propionate or cellulose diacetate can be used.

  Of these, polyesters such as polyethylene terephthalate and polyethylene naphthalate, acrylics such as cellulose acylate and polymethyl methacrylate, and polyolefins such as polycarbonate, polypropylene and cyclic polyolefin can be preferably used.

  Moreover, as base material sheet [II], the sheet | seat one side is a convex part surface shown by said base material sheet [I], and the sheet | seat whose other surface is a flat surface can also be used. In particular, in order to obtain an optical sheet, the base sheet [II] is preferably a prism sheet or a diffusion sheet.

In order to obtain a more excellent optical sheet, both the base sheet [I] and the base sheet [II] are prism sheets, or the base sheet [I] is a diffusion sheet and the base sheet [II]. ] Is a prism sheet, the base sheet [I] is preferably a prism sheet, and the base sheet [II] is preferably a diffusion sheet.
The adhesive composition of the present invention can exhibit a very excellent adhesive force in bonding between prism sheets, which has conventionally been difficult to obtain sufficient adhesive force, and in bonding a prism sheet and a diffusion sheet.

  When both the base sheet [I] and the base sheet [II] are prism sheets, both are arranged in a direction in which the axes of the convex lenses (prisms) are substantially orthogonal. That is, when the axis of the convex lens of the prism sheet of the base sheet [I] is arranged in the vertical direction, the axis of the convex lens of the prism sheet of the base sheet [II] is arranged in the parallel direction. .

  A cross-sectional view of one preferred embodiment of the laminate of the present invention is shown in FIG. The laminated body shown in FIG. 1 includes, in order from the bottom, a diffusion sheet 1, a cured body 5 of an adhesive composition, a prism sheet 2, a cured body 5 of an adhesive composition, a prism sheet 3, and a cured body 5 of an adhesive composition. An optical sheet in which the diffusion sheet 4 is laminated. The form in which the base sheet [I] and the base sheet [II] are both prism sheets is exemplified between the prism sheet 2 and the prism sheet 3, and the base sheet [I] is a prism sheet. The form in which the base sheet [II] is a diffusion sheet is exemplified between the prism sheet 3 and the diffusion sheet 4, and further, the base sheet [I] is a diffusion sheet, and the base sheet [II] is a prism sheet. The form which is is illustrated between the diffusion sheet 1 and the prism sheet 2. In addition, the figure shown in detail about bonding of this diffusion sheet 1 and the prism sheet 2 is shown in FIG.

  Moreover, the schematic exploded perspective view explaining the laminated body shown in FIG. 1 is shown in FIG. 2 (the hardening body 5 is not shown), and the prism sheet 2 and the prism sheet 3 are taken along XX ′ shown in FIG. A cross-sectional view taken along the line is shown in FIG.

  Here, as described above, the diffusion sheet 1 and the diffusion sheet 4 and the prism sheet 2 and the prism sheet 3 are manufactured by applying unevenness to the resin material using a concave transfer roller, a transfer template (stamper), an uneven roller, or the like. can do.

  Moreover, the diffusion sheet 1 and the diffusion sheet 4 are made of, for example, a plurality of beads having light diffusibility on an acrylic resin or epoxy on the surface (one side) of a transparent film (support) such as a PET film, a polycarbonate film, or polystyrene. It can also be manufactured by fixing with a binder such as a resin, urethane resin, olefin resin, etc., and has a predetermined light diffusion performance. The diffusion sheet 1 and the diffusion sheet 4 are mainly used for the purpose of reducing luminance unevenness in the backlight surface.

  Examples of the beads include acrylic beads, silica beads, barium sulfate, titanium oxide, and calcium silicate. For example, TDF-127 (manufactured by Toray Sehan Co., Ltd.), Opulse BS-080 (manufactured by Keiwa Co., Ltd.), D141 (manufactured by Tsujiden Co., Ltd.) and the like can be mentioned.

  The average particle size of the beads is preferably 100 μm or less, particularly preferably 50 μm or less, and further preferably 25 μm or less. Further, it is preferable that the diffusion sheet 1 and the diffusion sheet 4 have different average particle diameters of beads and have different light diffusion performance.

  In addition, as the prism sheet 2 and the prism sheet 3, for example, the surface of the base material 21 and the base material 31 such as a PET film, a polycarbonate film, and polystyrene may be provided with the arrayed prism pattern 22 and the prism pattern 32. It is often used for the purpose of concentrating backlight light and improving luminance.

  Examples of the material of the prism pattern 22 and the prism pattern 32 include acrylic photopolymer, polycarbonate, fluorene resin, and the like, but are not limited thereto. Also, the prism pattern 22 and the prism pattern 32 do not have to be strictly prismatic, and may be those having an R shape at the top, a wave film shape, or a downward prism shape.

  In the laminate of FIG. 1, the prism sheet 2 and the prism sheet 3 are bonded together by the cured body 5 of the adhesive composition of the present invention. Specifically, the adhesive composition is thinly coated on the flat surface of one prism sheet 3, and this prism sheet 3 is used to form the prism pattern surface (convex surface) of the other prism sheet 2 using the adhesive composition. Are bonded together and cured by curing the adhesive composition. At this time, the prism sheet 2 and the prism sheet 3 are point-bonded or line-bonded by the convex portion of the prism sheet 2.

  Further, the diffusion sheet 1 and the prism sheet 2 of FIG. 1 may be bonded by the cured body 5 of the adhesive composition of the present invention. Specifically, the adhesive composition is thinly coated on the flat surface of one prism sheet 2, and the prism sheet 2 is bonded to the convex surface of the diffusion sheet 1 using the adhesive composition, and the above-mentioned adhesion It can also adhere | attach by hardening an agent composition (FIG. 5).

  3 is a cross-sectional view of the prism sheet 2 and the prism sheet 3 in the exploded perspective view of FIG. 2 cut along X-X ′ shown in FIG. 2. As shown in the sectional view of FIG. 3, the prism pattern 22 of the prism sheet 2 and the prism pattern 32 of the prism sheet 3 may each be composed of a plurality of convex portions (prisms) having the same uneven height. The prism pattern 22 of the prism sheet 2 and the prism pattern 32 of the prism sheet 3 may be prism patterns having the same uneven height, or may be different.

  As another embodiment, as shown in the prism sheet 2 of FIG. 4, a plurality of protrusions (prisms) 8 that are one step higher than the prism pattern 22 having the same uneven height are arranged in the prism pattern 22 at regular intervals. A prism sheet may be used.

  As shown in FIG. 4, when a plurality of convex portions (prisms) 8 that are one step higher than the prism pattern 22 are arranged at regular intervals, only the higher convex portions (prisms) 8 are bonded. Among the plurality of convex portions, the interval at which the higher convex portion (prism) 8 is provided is 1/3 (one of the three convex portions is set as a higher convex portion) to 1 / from the viewpoint of improving luminance. 10 (one of the ten convex portions is set as a higher convex portion) is preferable.

  6 is a cross-sectional view of the diffusion sheet 1 and the prism sheet 2 in the exploded perspective view of FIG. 2 cut along X-X ′ shown in FIG. 2. 6 corresponds to the exploded view of FIG. 5 showing the combination of the diffusion sheet 1 and the prism sheet 2 in detail. As shown in the sectional view of FIG. 6, the prism pattern 22 of the prism sheet 2 has a regular pattern, and the diffusion layer 12 of the diffusion sheet 1 has a random pattern. The prism pattern 22 and the prism pattern 32 may be uniform in height and shape, or may be non-uniform. Further, the shape of the diffusion layer 12 may be random or regular.

<Method for producing laminate>
As a manufacturing method of the laminated body of this invention, the process of laminating | stacking base material sheet [I] and base material sheet [II] using the said adhesive composition, The process of hardening the said adhesive composition, Is provided.

  Specifically, after uniformly applying an adhesive composition, which is usually in a liquid state and adjusted in viscosity with a solvent, to the flat surface of the base sheet [II], the base sheet [I] is then passed through the adhesive composition. The adhesive composition is cured by laminating, pressing and applying active energy rays to the convex surface of the film, and a laminate is obtained.

  In coating such an adhesive composition on the flat surface of the substrate sheet [II], for example, a reverse coater, a gravure coater (direct, reverse, offset), a bar reverse coater, a roll coater, a die coater, a bar coater, A rod coater or the like can be used, or coating by a dipping method can be performed.

  For the bonding and pressure bonding, for example, a roll laminator or the like can be used, and the pressure is selected from a range of 0.1 to 10 MPa.

  For such active energy ray irradiation, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used. Curing by ultraviolet irradiation is advantageous from the standpoint of availability of the device and price. In addition, when performing electron beam irradiation, it can harden | cure even without using the said photoinitiator (B).

As a light source for such ultraviolet irradiation, a high pressure mercury lamp, an electrodeless lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, an LED lamp or the like is used.
Such ultraviolet irradiation is performed under conditions of ^{2 to} 3,000 mJ / cm ² , preferably 10 to 2,000 mJ / cm ² .

In particular, in the case of the high-pressure mercury lamp, for example, it is performed under conditions of 5 to 3,000 mJ / cm ² , preferably 50 to 2,000 mJ / cm ² .
In the case of the electrodeless lamp, for example, 2~2,000mJ / cm ^2, preferably at the conditions of 10~1,000mJ / cm ^2.

  The irradiation time varies depending on the type of the light source, the distance between the light source and the coating surface, the coating thickness, and other conditions, but may be usually from several seconds to several tens of seconds, and in some cases, may be a fraction of a second. On the other hand, in the case of the electron beam irradiation, for example, an electron beam having an energy in the range of 50 to 1,000 keV is used, and the irradiation amount is preferably 2 to 50 Mrad.

  Irradiation direction of such active energy rays (ultraviolet rays, electron beams, etc.) can be irradiated from any appropriate direction, but is not a convex surface of the base sheet [I] in terms of preventing deterioration of the laminate. It is preferable to irradiate from the surface side.

  Further, in the present invention, when curing by irradiating with active energy rays, the solvent used at the time of coating is removed by drying, and irradiation is performed after increasing the viscosity of the adhesive composition. From the viewpoint of the optical characteristics after the laminate is produced. The viscosity of the adhesive composition before irradiation is preferably 300 to 25,000 mPa · s, more preferably 500 to 20,000 mPa · s, and particularly preferably 1,000 to 18,000 mPa · s. If the viscosity is too low, the adhesive fills the unevenness of the base material, which may cause a decrease in optical properties. If the viscosity is too high, the adhesive force tends to decrease.

  The thickness of the adhesive layer in the laminate of the present invention obtained as described above is usually 0.01 to 20 μm, preferably 0.01 to 10 μm, particularly preferably 0.01 to 7 μm, more preferably 0.1 to 5 μm. It is. If the thickness is too thin, the cohesive strength of the adhesive force itself cannot be obtained, and the adhesive strength tends to be not obtained. If the thickness is too thick, the durability of the laminate tends to be reduced due to cracking or the like.

  The adhesive composition of the present invention is an adhesive having excellent adhesive strength at the initial stage and with the passage of time, and is obtained from the convex surface of the base sheet [I] having a convex surface and the base sheet [II] having a flat surface. Used for bonding flat surfaces, but is particularly suitable for bonding prism sheets (illustrated in FIG. 3), for bonding prism sheets and diffusion sheets (illustrated in FIG. 6), and for prisms. The sheet exhibits good adhesiveness without being influenced by the moisture content of the sheet itself, and does not require a drying step, and is excellent in production efficiency of the laminate.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis.

  Prior to the examples and comparative examples, the components of the adhesive composition shown below and the substrate sheet were prepared.

<Photocurable compound>
・ Ethylenically unsaturated monomer (A-1)
2- (Meth) acryloyloxypropylphthalic acid (“ACB-21” manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity 15,000 mPa · s at 25 ° C., molecular weight 263)
・ Ethylenically unsaturated monomer (A-2)
2- (Meth) acryloyloxypropylphthalic acid (“ACB-22” manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity 13,000 mPa · s at 25 ° C., molecular weight 263)
・ Ethylenically unsaturated monomer (A-3)
2- (Meth) acryloyloxypropylphthalic acid (“ACB-23” manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity 11,000 mPa · s at 25 ° C., molecular weight 263)
・ Benzyl acrylate (A'-1)
(“Viscoat # 160” manufactured by Osaka Organic Industry Co., Ltd., viscosity 2 mPa · s at 25 ° C., molecular weight 162)
・ Cyclohexyl acrylate (A'-2)
(Osaka Organic Industries “Biscoat # 155”, viscosity 3 mPa · s at 25 ° C., molecular weight 154)
・ Acryloylmorpholine (A'-3)
(“ACMO” manufactured by KJ Chemicals, viscosity 12 mPa · s at 25 ° C., molecular weight 141)
・ 2-hydroxyethyl acrylate (A'-4)
(“HEA” manufactured by Osaka Organic Industry Co., Ltd., viscosity 6 mPa · s at 25 ° C., molecular weight 116)

<Photoinitiator (B)>
(B-1): 1-hydroxycyclohexyl phenyl ketone (“Irgacure 184” manufactured by BASF)

<Base sheet [I], [II]>
Base material sheet [I]: Prism sheet The prism sheet has a pitch of 50 μm, an average height of irregularities of 25 μm (surface roughness Ra of 25 μm), and a vertex angle of 90 °.
Base sheet [II]: Biaxially stretched polyethylene terephthalate film (“Lumirror T60 # 50” manufactured by Toray Industries, Inc.)

[Example 1]
As a photocurable compound, 100 parts of the ethylenically unsaturated monomer (A-1) and 2 parts of a photopolymerization initiator (B-1) were stirred and mixed in a flask to obtain an adhesive composition.
A solution obtained by diluting the adhesive composition obtained above twice with ethyl acetate (viscosity at 25 ° C .: 4.7 mPa · s) on the base sheet [II] so that the thickness after drying becomes 10 μm. The substrate was coated with a bar coater and dried for 10 minutes with a dryer at 80 ° C. to obtain a base sheet [II] with an adhesive composition layer (the viscosity at 25 ° C. of the adhesive composition layer after drying was 15 , 000 mPa · s).

  The base material sheet with adhesive composition layer [II] so that the adhesive composition layer surface of the obtained base material sheet with adhesive composition layer [II] adheres to the prism pattern surface of the base material sheet [I]. And base material sheet [I] was bonded together using a 2 kg hand roller, and the lamination sheet was obtained.

The obtained laminated sheet is exposed to 500 mJ / cm ² with a UV irradiation machine (high pressure mercury lamp), the adhesive composition is cured, and the base sheet [II] with the adhesive composition layer is bonded to the base sheet [I]. A laminated body was obtained.
Using the laminate obtained above, performance evaluation was performed as follows, and the results are also shown in Table 1.

[Examples 2-3]
In Example 1 described above, a bonded laminate was obtained in the same manner except that the photocurable compound was changed to (A-2) to (A-3).

[Comparative Examples 1-4]
In Example 1 above, the photocurable compound was changed to (A′-1) to (A′-4), and the coating was applied so that the thickness after drying was 10 μm without dilution with ethyl acetate. Except for the above, an adhered laminate was obtained.
Using the laminate obtained above, performance evaluation was performed as follows, and the results are also shown in Table 1.

[Adhesion evaluation]
The laminate obtained above was 15 cm long and 2.5 cm wide and measured at 180 ° peel strength (N / 25 mm) at room temperature of 23 ° C. according to the adhesive strength measurement method of JIS Z 0237. The evaluation was based on the following criteria.

○: 180 ° peel strength was 40 mN / 25 mm or more.
X: The 180 ° peel strength was less than 40 mN / 25 mm.

[Optical evaluation]
The laminate obtained above is cut into 5 cm × 5 cm, and a printed matter on which 4 characters of 1 cm × 1.5 cm are written is placed 10 cm behind the laminate, and from the 20 cm front of the laminate over the laminate. Evaluation was made according to the following criteria depending on how the characters were seen when the characters were seen.

○: The transmitted light of the entire laminate sheet was scattered, and the prism sheet was functioning.
(Triangle | delta): There existed a part in which the transmitted light was not scattered in a part (less than 10% by area) of a laminated body sheet.
X: Many portions (10% or more in area) of the laminate sheet had portions where transmitted light was not scattered.

From the results of Table 1 above, the laminates of Examples 1 to 3 using the adhesive composition of the present invention were excellent in adhesiveness and optical properties, whereas low viscosity ethylenic unsaturated. The laminates of Comparative Examples 1, 2, and 4 using the monomer-containing adhesive composition were excellent in adhesiveness but did not satisfy the optical properties.
Further, the laminate of Comparative Example 3 using the adhesive composition containing a low-viscosity ethylenically unsaturated monomer did not satisfy both the adhesiveness and the optical properties.

  Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Japanese Patent Application No. 2006-233785) filed on Dec. 1, 2016, the contents of which are incorporated herein by reference.

  The adhesive composition of the present invention is very adhesive in bonding of the convex surface of the base sheet [I] having a convex surface and the flat surface of the base sheet [II] having a flat surface. Since it is excellent, it can be used for, for example, bonding of various optical films or sheets, and bonding of electronic parts, precision devices, packaging materials, display materials, and the like, in addition to the prism sheet adhesive application.

DESCRIPTION OF SYMBOLS 1 Diffusion sheet 2 Prism sheet 3 Prism sheet 4 Diffusion sheet 5 Hardened | cured material 8 of adhesive composition High convex part (prism)
DESCRIPTION OF SYMBOLS 11 Base material 12 Diffusion layer 21 Base material 22 Prism pattern 31 Base material 32 Prism pattern 41 Base material 42 Diffusion layer

Claims (8)

  An adhesive composition for bonding a convex surface of a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a base sheet [II] having a flat surface. An adhesive comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more. Composition.   The adhesive composition according to claim 1, wherein the ethylenically unsaturated monomer (A) has a molecular weight of 1,000 or less.   The adhesive composition according to claim 1 or 2, wherein the ethylenically unsaturated monomer (A) is contained in the photocurable compound in an amount of 20% by weight or more.   Furthermore, a photoinitiator (B) is contained, The adhesive composition of any one of Claims 1-3 characterized by the above-mentioned.   The adhesive composition according to any one of claims 1 to 4, wherein the base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 µm and the base sheet [II] having a flat surface are used. A laminated body characterized by being laminated through an adhesive made of a product.   The laminate according to claim 5, wherein the base sheet [I] and the base sheet [II] are respectively a prism sheet or a diffusion sheet.   Using the adhesive composition according to any one of claims 1 to 4, a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 µm and a base sheet having a flat surface [ II] and a step of curing the adhesive composition.   An adhesive composition comprising a photocurable compound, wherein the photocurable compound contains an ethylenically unsaturated monomer (A) having a viscosity at 25 ° C. of 3,000 mPa · s or more, Use for bonding the convex surface of the base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and the flat surface of the base sheet [II] having a flat surface.

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