JP6699132B2 - Photocurable composition, laminated body using the same, and light guide plate - Google Patents

Description

  The present invention relates to a photocurable composition, a laminated body using the same, and a light guide plate. Specifically, the present invention relates to a photocurable composition having high transparency and excellent hard coat properties, a laminate using the same, and a light guide plate.

  A transmission type image display device such as a liquid crystal display device generally has, as a backlight, a surface light source device that supplies planar light by a light guide plate. As the method of the surface light source device, there are a direct type in which a light source is provided on the back side of the light guide plate and an edge light method in which the light source is provided along the side surface of the light guide plate. The edge light method is advantageous from the viewpoint of thinning the image display device.

  In an edge light type surface light source device, light incident from the side surface of the light guide plate is reflected by the action of a light distribution pattern (for example, a light distribution pattern composed of light reflection dots) provided on the back side of the light guide plate in an uneven shape. And diffused (scattered), and light having an angle component equal to or greater than the critical angle is emitted from the emission surface of the light guide plate to supply planar light.

  In recent years, a sheet material made of polycarbonate or the like having high strength has begun to be used as the light guide plate. However, since the surface of a polycarbonate sheet is easily scratched, it is necessary to hard coat the surface of such a sheet with a highly transparent resin to increase the surface hardness (pencil hardness).

  On the other hand, since polycarbonate generally has weak adhesion to other resins, if a polycarbonate sheet is used as a base material, it is necessary to hard coat the resin with the adhesion to the base material.

  Further, in the above-mentioned light guide plate, it is considered to achieve an uneven light distribution pattern by providing a surface uneven layer. That is, the unevenness is formed on the surface of the polycarbonate sheet, and the uneven surface is not treated by hard coating with a hard coating agent, but by using a photocurable composition, the surface of the flat polycarbonate sheet surface is compared. A method of forming the uneven layer by 2p has been studied. Then, as described above, in order to form 2p of the surface uneven layer using the photocurable composition, it is important that the photocurable composition has an appropriate viscosity from the viewpoint of processability. Further, it is advantageous in terms of cost and productivity that the function as the surface uneven layer and the function as the hard coat layer are integrated.

  Further, in order to use the 2p molded product as a light guide plate as described above, it is important to have a high refractive index from the viewpoint of light extraction efficiency, and preferably a high refractive index of 1.57 or more. It has been demanded.

  Against this technical background, in recent years, a resin composition using a (meth)acrylic monomer having a biphenyl structure has been developed (see Patent Document 1). Also, many resin compositions using urethane (meth)acrylate compounds have been developed (see Patent Documents 2 to 5).

Japanese Patent No. 5340460 JP, 2005-68331, A JP, 2014-164133, A JP, 2009-173863, A WO2012/141275

However, the resin composition of Patent Document 1 has problems such as insufficient pencil hardness (surface hardness) at the time of curing, difficulty in 2p molding due to too low viscosity, and poor adhesion to a substrate. Problems remain as the photocurable composition for forming the hard coat layer as described above.
Further, the resin compositions of Patent Documents 2 to 5 have problems such as insufficient pencil hardness at the time of curing and insufficient refractive index. Therefore, these resin compositions also have the above-mentioned hard coat. It is insufficient as a photocurable composition for forming a layer.

  The present invention has been made in view of the above circumstances, a photocurable composition having a high pencil hardness during curing and excellent hard coat characteristics and a high refractive index, and a laminate using the same, and a conductor. The purpose is to provide a light board.

The present inventors have conducted intensive studies in view of the above circumstances. In the process, a high refractive index is realized by using a (meth)acrylic monomer having a biphenyl structure as a photocurable composition, and by using a urethane (meth)acrylate compound in combination therewith, It was investigated to improve the hard coat properties while achieving a viscosity suitable for forming the hard coat layer. However, since just it was not obtained the desired pencil hardness, the present inventors have evolving, the urethane (meth) acrylate compound, possess 4 or more ethylenically unsaturated groups, a carbonate structure as a result of what is Yes, we have found that desired objects can be achieved.
Usually, the urethane (meth)acrylate-based compound is obtained by reacting a hydroxyl group-containing (meth)acrylate-based compound with a polyvalent isocyanate-based compound, and a hydroxyl group is added to both ends of the urethane (meth)acrylate-based compound. It has a double bond (ethylenically unsaturated group, that is, a (meth)acrylate group) derived from the contained (meth)acrylate compound. On the other hand, the present inventors have increased the amount of the hydroxyl group-containing (meth)acrylate-based compound in the urethane (meth)acrylate-based compound to be an ethylenically unsaturated group (which serves as a crosslinking point when photocured). When the number of (meth)acrylate groups is 4 or more to have a carbonate structure, the crosslinking density when photocured is increased while maintaining a high refractive index without lowering the refractive index, and the desired pencil is obtained. The inventors of the present invention have completed the present invention by finding that hardness can be obtained.

That is, the first gist of the present invention is to contain a (meth)acrylic monomer (A) having a biphenyl structure and a urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups ,
The urethane (meth)acrylate compound (B) having 4 or more ethylenically unsaturated groups is a urethane (meth)acrylate compound having a carbonate structure,
The content ratio (A/B) of the (meth)acrylic monomer (A) having a biphenyl structure and the urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups is a weight ratio, A/B=50/50 to 90/10 The present invention relates to a photocurable composition.

  Further, in the present invention, the second gist is a laminated body characterized in that a cured resin layer comprising the photocurable composition of the first gist is laminated on at least one surface of a base material.

  Further, in the present invention, a light guide plate, which is the laminated body of the second aspect, is a third aspect.

  As described above, the photocurable composition of the present invention comprises a (meth)acrylic monomer (A) having a biphenyl structure and a urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups. Since it contains, it is possible to exhibit a high pencil hardness, excellent hard coat properties, and a high refractive index by photocuring. Further, it has a viscosity suitable for forming a hard coat layer, and can exhibit excellent workability even when it is molded by 2p.

In particular, having a biphenyl structure (meth) acrylic monomer (A), since the content of the urethane having an ethylenically unsaturated group 4 or more (meth) acrylate compound (B) is within a specific range , And becomes superior due to the balance between high refractive index and hard coat properties.

Also, urethane having an ethylenically unsaturated group 4 or more (meth) acrylate compound (B) is, since a urethane (meth) acrylate compound having a carbonate structure, to the plastic substrate (especially a polycarbonate substrate) The adhesion will be better.

  Furthermore, when the weight average molecular weight of the urethane (meth)acrylate compound (B) having 4 or more ethylenically unsaturated groups is within a specific range, the coatability will be improved.

  When the photocurable composition of the present invention further contains a photopolymerization initiator (C), it can be cured by irradiation with active energy rays such as ultraviolet rays for a very short time.

  Further, when the viscosity of the photocurable composition at 20° C. is within a specific range, it becomes more excellent in coatability and the like.

  Then, a laminate in which a cured resin layer made of the photocurable composition is laminated on at least one surface of the substrate, the cured resin layer has high pencil hardness and excellent hard coat properties, and exhibits a high refractive index. be able to. Further, the cured resin layer having an uneven structure on its surface can have an uneven surface having high reproducibility by 2p molding or the like. From this, the laminated body can be suitably used as a light guide plate, a prism sheet, a diffusion plate or the like depending on the type of the base material and the pattern of the uneven structure.

It is sectional drawing which shows an example of a light guide plate.

  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)acrylic” is a generic term for acrylic and methacrylic.

<Photocurable composition>
The photocurable composition of the present invention contains a (meth)acrylic monomer (A) having a biphenyl structure and a urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups. is there. Below, the detail of the component of the said photocurable composition is demonstrated.

[(Meth)acrylic Monomer (A) Having Biphenyl Structure]
As the (meth)acrylic monomer (A), any compound having a biphenyl structure in its molecular structure may be used, and among them, for example, a compound represented by the following general formula (1) is used.

  In the compound represented by the general formula (1), the substitution position of the biphenyl group is the ortho position or the para position, and X is a divalent organic group having 1 to 12 carbon atoms from the viewpoint of high refractive index. preferable. From the same viewpoint, as the (meth)acrylic monomer (A), a compound represented by the following general formula (2) is more preferably used.

[Urethane (meth)acrylate compound (B) having 4 or more ethylenically unsaturated groups]
The urethane (meth)acrylate-based compound (B) is a compound having an ethylenically unsaturated group and a urethane bond, and particularly, a hydroxyl group-containing (meth)acrylate-based compound (b1) and a polyvalent isocyanate-based compound (b2). Examples thereof include a reaction product and a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2) and a polyol compound (b3). Among them, the reaction product of the hydroxyl group-containing (meth)acrylate compound (b1), the polyvalent isocyanate compound (b2) and the polyol compound (b3) is particularly preferable from the viewpoint of adhesion to the substrate. It is a urethane (meth)acrylate compound (B1).
The urethane (meth)acrylate compound (B) has four or more double bonds (ethylenically unsaturated group, that is, (meth)acrylate group) derived from the hydroxyl group-containing (meth)acrylate compound (b1). It has, preferably 5 or more, particularly preferably 6 or more. That is, if the amount of the ethylenically unsaturated groups is too small, the desired pencil hardness cannot be obtained. Further, when the amount of the ethylenically unsaturated group is too large, there is a possibility that a problem such as curing shrinkage becomes large, so that the upper limit of the number of the ethylenically unsaturated groups is 20, preferably 12. ..

Examples of the hydroxyl group-containing (meth)acrylate compound (b1) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth). ) Acrylate, hydroxyalkyl(meth)acrylate such as 6-hydroxyhexyl(meth)acrylate, 2-hydroxyethylacryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl( (Meth)acrylate, dipropylene glycol (meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl A hydroxyl group-containing (meth)acrylate compound containing one ethylenically unsaturated group such as (meth)acrylate;
A hydroxyl group-containing (meth)acrylate compound containing two ethylenically unsaturated groups such as glycerin di(meth)acrylate and 2-hydroxy-3-acryloyl-oxypropyl methacrylate;
Pentaerythritol tri(meth)acrylate, caprolactone modified pentaerythritol tri(meth)acrylate, ethylene oxide modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone modified dipentaerythritol penta(meth)acrylate, ethylene Examples thereof include hydroxyl group-containing (meth)acrylate compounds containing three or more ethylenically unsaturated groups such as oxide-modified dipentaerythritol penta(meth)acrylate.
These hydroxyl group-containing (meth)acrylate compounds (b1) can be used alone or in combination of two or more.

  Among these, a hydroxyl group (meth)acrylate compound having two or more ethylenically unsaturated groups is preferable from the viewpoint of producing a urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups. ..

Examples of the polyvalent isocyanate compound (b2) include aromatic compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate. System polyisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, aliphatic polyisocyanate such as lysine triisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, Alicyclic polyisocyanates such as 1,3-bis(isocyanatomethyl)cyclohexane, trimer compounds or multimer compounds of these polyisocyanates, allophanate type polyisocyanates, burette type polyisocyanates, water-dispersed polyisocyanates, etc. can give.
These polyvalent isocyanate compounds (b2) can be used alone or in combination of two or more.

  Among these, diisocyanate compounds are preferable from the viewpoint of stability during urethanization reaction, and in particular, aliphatic diisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane. Aliphatic diisocyanates such as diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane are preferably used, and more preferably isophorone diisocyanate and water in that curing shrinkage is small. Hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate and norbornene diisocyanate are used, and particularly preferably hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate and isophorone diisocyanate are used because of their excellent reactivity and versatility.

The polyol-based compound (b3) may be a compound containing two or more hydroxyl groups, and examples thereof include polycarbonate-based polyols, aliphatic polyols, alicyclic polyols, polyether-based polyols, polyester-based polyols, polyolefin-based polyols. , Polybutadiene-based polyols, polyisoprene-based polyols, (meth)acrylic-based polyols, polysiloxane-based polyols and the like.
These polyol compounds (b3) can be used alone or in combination of two or more.

Of these, polycarbonate-based polyols are important from the viewpoint of adhesion to the substrate. That is, the urethane (meth)acrylate-based compound (B) having four or more ethylenically unsaturated groups is a urethane (meth)acrylate-based compound having a carbonate structure relative to the plastic substrate (particularly polycarbonate substrate). adhesion, ing as more excellent.

  Examples of the polycarbonate-based polyol include a reaction product of a polyhydric alcohol and phosgene, a ring-opening polymerization product of a cyclic carbonic acid ester (alkylene carbonate, etc.), and the like.

  Examples of the polyhydric alcohol used in the polycarbonate-based polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, and 2-methyl. -1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5 -Pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (1,4-cyclohexanediol etc.), bisphenols (bisphenol A etc.), sugar alcohols (xylitol, sorbitol etc.) and the like can be mentioned.

  Examples of the alkylene carbonate used in the above polycarbonate-based polyol include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate and the like.

  The polycarbonate-based polyol may be a compound having a carbonate bond in the molecule and a hydroxyl group at the terminal, and may have an ester bond in addition to the carbonate bond.

  The aliphatic polyols exemplified as the polyol compound (b3) include, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2-diethyl. -1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol , 1,5-pentamethylenediol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, pentaerythritol diacrylate, 1, Aliphatic alcohols containing two hydroxyl groups such as 9-nonanediol and 2-methyl-1,8-octanediol, sugar alcohols such as xylitol and sorbitol, 3 such as glycerin, trimethylolpropane and trimethylolethane. Examples thereof include aliphatic alcohols containing one or more hydroxyl groups.

  Examples of alicyclic polyols exemplified as the polyol compound (b3) include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tris Examples thereof include cyclodecane dimethanol.

  Examples of the polyether polyol exemplified as the polyol compound (b3) include alkylene structures such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol and polyhexamethylene glycol. Examples thereof include polyether-based polyols and random or block copolymers of these polyalkylene glycols.

  Examples of the polyester polyol exemplified as the polyol compound (b3) include, for example, a condensation polymer of a polyhydric alcohol and a polycarboxylic acid, a ring-opening polymer of a cyclic ester (lactone), a polyhydric alcohol, Examples thereof include reaction products of three kinds of components of polyvalent carboxylic acid and cyclic ester.

Examples of the polyhydric alcohol include the polyhydric alcohols exemplified in the description of the polycarbonate polyol.
Examples of the polycarboxylic acid include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and aromatic dicarboxylic acids such as trimellitic acid.
Examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, ε-caprolactone and the like.

  Examples of the polyolefin-based polyol exemplified as the polyol-based compound (b3) include those having a homopolymer or copolymer of ethylene, propylene, butene or the like as a saturated hydrocarbon skeleton, and having a hydroxyl group at its molecular end. ..

Examples of the polybutadiene-based polyol exemplified as the polyol-based compound (b3) include those having a copolymer of butadiene as a hydrocarbon skeleton and having a hydroxyl group at its molecular end.
The polybutadiene-based polyol may be a hydrogenated polybutadiene polyol obtained by hydrogenating all or part of the ethylenically unsaturated groups contained in its structure.

Examples of the polyisoprene-based polyol exemplified as the polyol-based compound (b3) include those having a copolymer of isoprene as a hydrocarbon skeleton and having a hydroxyl group at its molecular end.
The polyisoprene-based polyol may be a hydrogenated polyisoprene polyol obtained by hydrogenating all or part of the ethylenically unsaturated groups contained in the structure.

  The (meth)acrylic polyol exemplified as the polyol compound (b3) has at least two hydroxyl groups in the molecule of the polymer or copolymer of (meth)acrylic acid ester. Examples of such (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and hexyl (meth)acrylate. , Octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, and the like (meth)acrylic acid alkyl ester. ..

  Examples of the polysiloxane polyol exemplified as the polyol compound (b3) include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

  In the present invention, the number average molecular weight of the polyol compound (b3) is preferably 200 to 3,000, particularly preferably 250 to 2,000, further preferably 300 to 1,000. If the number average molecular weight is too small, the crosslinking density tends to be too high, resulting in poor adhesion to the substrate. If it is too large, the crystallinity tends to be high and the viscosity tends to be high.

The above-mentioned number average molecular weight is the number average molecular weight in terms of standard polystyrene molecular weight, and is used for high performance liquid chromatography (manufactured by Nippon Waters Co., Ltd., "Waters 2695 (main body)" and "Waters 2414 (detector)"). : Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , theoretical plate number: 10000 plates/piece, filler material: styrene-divinylbenzene copolymer, filler particle size : 10 μm) in series.

  In the present invention, the urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups (hereinafter, may be abbreviated as “urethane (meth)acrylate compound (B)”) is as follows. Can be manufactured as follows. The following explanation is about a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2) and a polyol compound (b3). By carrying out the reaction, a product obtained by reacting the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2) can also be produced.

For example,
(1) A method in which the above-mentioned hydroxyl group-containing (meth)acrylate compound (b1), polyvalent isocyanate compound (b2), and polyol compound (b3) are charged in a reactor all at once or separately and reacted.
(2) A method of reacting a hydroxyl group-containing (meth)acrylate compound (b1) with a reaction product obtained by previously reacting the polyol compound (b3) and the polyvalent isocyanate compound (b2),
(3) A method of reacting the polyol compound (b3) with a reaction product obtained by previously reacting the polyvalent isocyanate compound (b2) and the hydroxyl group-containing (meth)acrylate compound (b1), and the like. However, the method (2) is preferable from the viewpoints of reaction stability and reduction of by-products.

  For the reaction of the polyol compound (b3) and the polyvalent isocyanate compound (b2), known reaction means can be used. At that time, for example, the molar ratio of the isocyanate group in the polyvalent isocyanate compound (b2) to the hydroxyl group in the polyol compound (b3) is usually about 2n:(2n-2) (n is an integer of 2 or more). By doing so, a terminal isocyanate group-containing urethane (meth)acrylate compound having an isocyanate group remaining can be obtained, and after the compound is obtained, an addition reaction with a hydroxyl group-containing (meth)acrylate compound (b1) is performed. It can be carried out.

  A known reaction is also applied to the addition reaction of the reaction product obtained by previously reacting the polyol compound (b3) with the polyvalent isocyanate compound (b2) and the hydroxyl group-containing (meth)acrylate compound (b1). Means can be used.

  The reaction molar ratio between the reaction product and the hydroxyl group-containing (meth)acrylate compound (b1) is, for example, two isocyanate groups in the polyvalent isocyanate compound (b2) and the hydroxyl group-containing (meth)acrylate compound (b1). 2) has one hydroxyl group, the reaction product: hydroxyl group-containing (meth)acrylate compound (b1) is about 1:2, and the polyvalent isocyanate compound (b2) has three isocyanate groups. When the hydroxyl group-containing (meth)acrylate compound (b1) has one hydroxyl group, the reaction product:hydroxyl group-containing (meth)acrylate compound (b1) is about 1:3.

  In the addition reaction of this reaction product with the hydroxyl group-containing (meth)acrylate compound (b1), the reaction is terminated when the residual isocyanate group content of the reaction system is usually 0.5% by weight or less, A urethane (meth)acrylate compound (B) is obtained.

  In the reaction between the polyol compound (b3) and the polyvalent isocyanate compound (b2) and the reaction product thereof with the hydroxyl group-containing (meth)acrylate compound (b1), a catalyst is used for the purpose of promoting the reaction. It is also preferable to use, and examples of such a catalyst include organic metal compounds such as dibutyltin dilaurate, trimethyltin hydroxide, tetra-n-butyltin, zinc octenoate, tin octenoate, cobalt naphthenate, and stannous chloride. , Metal salts such as stannic chloride, triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N', Amine catalysts such as N'-tetramethyl-1,3-butanediamine and N-ethylmorpholine, bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide, etc., and organic such as dibutylbismuth dilaurate, dioctylbismuth dilaurate Bismuth compound, bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate Bismuth-based catalysts such as salts, bismuth acetate salts, bismuth ribis neodecanoate, bismuth disalicylate, bismuth digallic acid salts and other organic acid bismuth salts, zirconium-based catalysts such as inorganic zirconium, organic zirconium and zirconium alone, 2 Examples thereof include those in which two or more kinds of catalysts such as zinc ethylhexanoate/zirconium tetraacetylacetonate are used in combination, and among them, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferable. . In addition, these catalysts may be used individually by 1 type, and may use 2 or more types together.

  Further, in the reaction between the polyol compound (b3) and the polyvalent isocyanate compound (b2), and further the reaction product thereof with the hydroxyl group-containing (meth)acrylate compound (b1), the reaction with the isocyanate group is performed. It is possible to use an organic solvent having no functional group such as, for example, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatic solvents such as toluene and xylene.

  The reaction temperature is generally 30 to 90° C., preferably 40 to 80° C., and the reaction time is generally 2 to 10 hours, preferably 3 to 8 hours.

Thus, the urethane (meth)acrylate compound (B) is obtained.
The weight average molecular weight of the urethane (meth)acrylate compound (B) is preferably 1000 to 20000, more preferably 1200 to 15000, and further preferably 1500 to 10000. That is, when the weight average molecular weight is too small, the viscosity is lowered, and when it is applied to the substrate, it tends to cause cissing, and when it is too large, the viscosity is increased, and there is a tendency that it cannot be applied to the substrate at room temperature. is there.

The above-mentioned weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and is used for high performance liquid chromatography (Showa Denko KK, "Shodex GPC system-11 type"), column: Shodex GPC KF-806L (excluded). Limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , theoretical plate number: 10000 plates/piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) It is measured by using.

Regarding the viscosity of the urethane (meth)acrylate compound (B), the viscosity at 60° C. is preferably 500 to 100000 mPa·s, particularly 800 to 50000 mPa·s, and further 1000 to 35000 mPa·s. Is preferred. If the viscosity is too high, a large amount of diluent must be used, and the workability tends to decrease. If it is too low, the adhesion to the substrate tends to decrease.
The viscosity is measured by an E-type viscometer.

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

  Examples of the photopolymerization initiator (C) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, and 4-(2-hydroxyethoxy)phenyl-(2. -Hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 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 Benzoins such as ethers; 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]benzenemethanaminium bromide, (4-benzoylbenzyl ) Benzophenones such as trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-). 2-Hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one thioxanthones such as mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2 , 4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and other acylphosphine oxides; and the like. In addition, as for these photoinitiators (C), only 1 type may be used independently and 2 or more types may be used together.

  Further, as these auxiliaries, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid Ethyl, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone It is also possible to use the above together.

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

[Other]
In the photocurable composition of the present invention, in addition to the above components, other monomers, antioxidants, flame retardants, antistatic agents, fillers, leveling agents, stabilizers in addition to the above components It is also possible to add a reinforcing agent, a matting agent or the like. And, the compounding amount of these additives is preferably 30% by weight or less, and particularly preferably 20% by weight or less of the whole composition. Further, the content of the above-mentioned other monomer is preferably 30% by weight or less, particularly preferably 20% by weight or less, and further preferably 10% by weight or less based on the whole composition.

  Examples of the other monomer include, for example, an ethylenically unsaturated compound having one ethylenically unsaturated group (monofunctional monomer) and an ethylenically unsaturated compound having two or more ethylenically unsaturated groups (polyfunctional monomer). (Monomer) is used.

Examples of the monofunctional monomer include styrene, vinyltoluene, chlorostyrene, α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, acrylonitrile, vinyl acetate, 2-hydroxyethyl (meth)acrylate, 2- Hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3 -Chloro-2-hydroxypropyl (meth)acrylate, glycerin mono (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth) Acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, Octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, benzyl (meth)acrylate, cyclic trimethylolpropane formal ( (Meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenol ethylene oxide modified (n=2) (meth)acrylate, nonylphenol propylene oxide modified (n=2.5) (meth)acrylate, 2-(meth)acryloyloxyethyl Half (meth)acrylate, furfuryl (meth)acrylate, carbitol (meth)acrylate, ethylcarbitol (meth)acrylate of a phthalic acid derivative such as acid phosphate and 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, ( 3-ethyloxetane-3-yl)methyl (meth)acrylate, benzyl (meth)acrylate, butoxyethyl (meth)acrylate, allyl (meth)acrylate, acryloylmorpholine, dimethylacrylamide, 2-hydroxyethylacrylamide, N-methylol ( (Meth)acrylamide, N-vinylpyrrolidone, 2-vinyl Examples include rupyridine and polyoxyethylene secondary alkyl ether acrylate.
Further, for example, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, N- Hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, mercaptoethyl( Examples also include monomers having a proton-accepting group such as (meth)acrylamide, N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.
Further, in addition thereto, a Michael adduct of acrylic acid or 2-acryloyloxyethyldicarboxylic acid monoester can be used in combination, and as the Michael adduct of acrylic acid, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid can be used. Examples thereof include trimer, tetramer acrylic acid, and tetramer methacrylic acid. Further, the 2-acryloyloxyethyl dicarboxylic acid monoester is a carboxylic acid having a specific substituent, for example, 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxy. Examples thereof include ethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahydrophthalic acid monoester and 2-methacryloyloxyethyl hexahydrophthalic acid monoester. Furthermore, other oligoester acrylates are also included.

Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth). Acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide modified bisphenol A type Di(meth)acrylate, propylene oxide-modified bisphenol A type di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, ethoxylated cyclohexanedimethanol di(meth)acrylate, dimethyloldicyclopentanedi(meth)acrylate, tri Cyclodecane dimethanol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol di Bifunctional monomers such as glycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, hydroxypivalic acid modified neopentyl glycol di(meth)acrylate, isocyanuric acid ethylene oxide modified diacrylate;
Trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxy Trimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, isocyanuric acid ethylene oxide modified tri(meth)acrylate, caprolactone modified dipentaerythritol penta(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate, caprolactone modified penta Erythritol tri(meth)acrylate, caprolactone modified pentaerythritol tetra(meth)acrylate, ethylene oxide modified dipentaerythritol penta(meth)acrylate, ethylene oxide modified dipentaerythritol hexa(meth)acrylate, ethylene oxide modified pentaerythritol tri(meth)acrylate Trifunctional or higher functional monomers such as acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, and ethoxylated glycerin triacrylate;
Can be given.

  Further, the photocurable composition of the present invention may contain a solvent or may be used as a solventless composition, but a solventless composition in which the step of drying the solvent can be omitted. Is preferably used as.

[Preparation of photocurable composition]
The photocurable composition of the present invention comprises a (meth)acrylic monomer (A) having a biphenyl structure, a urethane (meth)acrylate compound (B), a photopolymerization initiator (C), and if necessary. Then, the above various additives can be prepared by blending them in a predetermined blending amount and mixing.

In the photocurable composition of the present invention, the content ratio (A/B) of the (meth)acrylic monomer (A) having a biphenyl structure and the urethane (meth)acrylate compound (B) is a weight ratio, It is important that A/B= 50 / 50 to 90/10 from the viewpoint of a balance between high refractive index and hard coat properties. From the same viewpoint, it is particularly preferable that A/B= 50 / 50 to 85/15, and further A/B= 50 / 50 to 80/20. That is, if A/B is too small, the refractive index tends to decrease, and if A/B is too large, the crosslinking density tends to decrease and the pencil hardness tends to decrease.

  Regarding the content of the photopolymerization initiator (C), based on 100 parts by weight of the total amount of the (meth)acrylic monomer (A) having a biphenyl structure and the urethane (meth)acrylate compound (B), It is preferably 0.1 to 10 parts by weight, particularly preferably 0.2 to 7 parts by weight, further preferably 0.3 to 5 parts by weight. If the content of the photopolymerization initiator (C) is too small, the curability tends to be poor and the physical properties tend to be unstable, and if it is too large, the transparency of the cured product tends to deteriorate and the weather resistance tends to deteriorate. There is.

The viscosity at 20° C. of the photocurable composition of the present invention is preferably 300 to 30,000 mPa·s, particularly 500 to 20,000 mPa·s, and further 700 to 10,000 mPa·s, from the viewpoint of coatability and the like. Is preferred. That is, if the viscosity is too low, it tends to cause cissing when applied to the substrate, and if it is too high, it tends to be difficult to apply to the substrate at room temperature.
The viscosity is measured by an E-type viscometer.
Thus, the photocurable composition of the present invention is obtained.

<Laminate>
At least one surface of the substrate, a laminate formed by laminating a cured resin layer comprising the photocurable composition of the present invention, the cured resin layer has a high pencil hardness and excellent hard coat properties, high refractive index. Can be shown. Further, as described above, the urethane of the photocurable composition (meth) acrylate compound (B) is, since a urethane (meth) acrylate compound having a carbonate structure, the base material is a plastic The adhesiveness of the cured resin layer becomes more excellent than that of the base material (particularly the polycarbonate base material). Further, the cured resin layer having an uneven structure on its surface can have an uneven surface having high reproducibility by 2p molding or the like. From this, the laminated body can be suitably used as a light guide plate, a prism sheet, a diffusion plate or the like depending on the type of the base material and the pattern of the uneven structure.

  The base material is preferably polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester (polyethylene terephthalate, polyethylene naphthalate, etc.), polyolefin (polypropylene, cyclic polyolefin, etc.), acrylic (polymethyl methacrylate). Etc.), polystyrene, polycarbonate, polyamide, biaxially stretched polyethylene terephthalate, polyethylene naphthalate, polyamide imide, polyimide, aromatic polyamide, cellulose acylate, cellulose triacetate, cellulose acetate propionate, cellulose diacetate, etc. , A transparent sheet is used. Among them, a sheet made of polymethylmethacrylate, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, cyclic polyolefin is effective as a base sheet for a light guide plate, and in particular, polycarbonate is excellent as a base sheet for a light guide plate. There is.

  Here, FIG. 1 shows an example of the light guide plate. As shown in FIG. 1, a flat substrate sheet 1 for a light guide plate is used, and a surface uneven layer 2 laminated on the substrate sheet 1 is used as a cured resin layer made of the photocurable composition of the present invention. And The cured resin layer comprising the photocurable composition of the present invention has a high pencil hardness and excellent hard coat characteristics, and can exhibit a high refractive index. Therefore, the surface uneven layer 2 functions as a surface uneven layer. , And the function as a hard coat layer are integrated. Therefore, it is also advantageous in terms of cost and productivity.

  Further, by forming the uneven surface by 2p molding, the surface uneven layer 2 has high reproducibility of the unevenness formed on the inner peripheral surface (mold surface) of a molding die such as a glass mold.

  The formation of the surface uneven layer 2 is not limited to 2p molding, and for example, the surface of the base sheet 1 is coated with the photocurable composition of the present invention and photocured to form a flat cured resin layer. After forming, on the surface of the cured resin layer, a method of forming an uneven surface by cutting with a laser or a plotter, a method of forming the uneven surface by applying the photocurable composition by silk printing, etc. It may be.

  In applying the photocurable composition onto the flat surface of the substrate sheet 1, for example, a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod. It is possible to use a coater or the like, or to perform coating by a dipping method.

  In addition, irradiation with active energy rays necessary for curing the photocurable composition includes light rays such as deep ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, Although neutron rays and the like can be used, curing by ultraviolet irradiation is advantageous in terms of curing speed, availability of irradiation equipment, and cost. In the case of performing electron beam irradiation, it can be cured without using the photopolymerization initiator (C).

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 and the like are used as a light source when performing such ultraviolet irradiation.
Such ultraviolet irradiation is performed under the condition of ^{2 to} 3000 mJ/cm ² , preferably 10 to 2000 mJ/cm ² .

Particularly if the high-pressure mercury lamp, for example, 5~3000mJ / cm ^2, preferably at the conditions of 50~2000mJ / cm ^2.
Further, in the case of the above electrodeless lamp, for example, it is performed under the conditions of ^{2 to} 2000 mJ/cm ² , preferably 10 to 1000 mJ/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 is usually several seconds to several tens of seconds, and in some cases, it 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 1000 keV is preferably used and the irradiation amount is 2 to 50 Mrad.

  The thickness of the cured resin layer in the laminate of the present invention obtained as described above is usually 1 to 3000 μm, preferably 2 to 2000 μm, particularly preferably 3 to 1000 μm, and further preferably 5 to 500 μm. Further, in the light guide plate, the thickness of the cured resin layer is usually 1 to 1000 μm, preferably 2 to 700 μm, particularly preferably 3 to 500 μm, and further preferably 5 to 300 μm.

  In the light guide plate, the thickness of the substrate sheet is usually 10 to 2000 μm, preferably 30 to 1000 μm, particularly preferably 50 to 800 μm, and further preferably 100 to 700 μm.

The size (depth/height) and shape of each concave portion (convex portion) on the uneven surface of the cured resin layer in the light guide plate are not particularly limited, but for example, a dot pattern, a line pattern, a grid It is preferably a pattern. Further, the pattern of the uneven surface of the light guide plate is preferably a dot pattern.
The depth (height) of each recess (projection) on the uneven surface of the cured resin layer of the light guide plate is usually 1 to 1000 μm, preferably 2 to 500 μm, particularly preferably 3 to 300 μm, and further preferably Is 5 to 200 μm.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.
In addition, "part" and "%" in the examples mean weight basis.

  Prior to the Examples and Comparative Examples, urethane (meth)acrylate compounds (B-1, B-2, B') shown below were synthesized.

<Synthesis of hexafunctional urethane (meth)acrylate compound (B-1)>
In a four-necked flask equipped with a thermometer, a stirrer, a water-cooled condenser, and a nitrogen gas inlet, 19.9 g (0.09 mol) of isophorone diisocyanate, 36.1 g of polycarbonate diol (hydroxyl value 139.5 mg KOH/g; hydroxyl value (Molecular weight calculated from 804; 0.07 mol) and 0.01 g of dibutyltin dilaurate as a reaction catalyst were charged and reacted at 60°C. When the residual isocyanate group became 6.7% or less, pentaerythritol triacrylate [a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (hydroxyl value 120 mgKOH/g)] 44.0 g (0.09 mol), polymerization Methoxyphenol 0.04 g was further charged as an inhibitor and reacted at 60° C., the reaction was terminated when the residual isocyanate group was 0.3% or less, and the urethane (meth)acrylate compound (B-1) ( The number of functional groups: 6 and the weight average molecular weight: about 6000) were obtained.

<Synthesis of hexafunctional urethane (meth)acrylate compound (B-2)>
In a flask equipped with a thermometer, a stirrer, a water-cooled condenser, and a nitrogen gas blowing port, 219.0 g (0.84 mol) of dicyclohexylmethane diisocyanate and pentaerythritol triacrylate (a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate ( Hydroxyl value 120 mg KOH/g)] 781.0 g (1.67 mol) were charged, 0.01 g of hydroquinone methyl ether as a polymerization inhibitor and 0.01 g of dibutyltin dilaurate as a reaction catalyst were charged, and the mixture was reacted at 60° C. for 8 hours and left. The reaction was terminated when the isocyanate group content was 0.3% or less, and a urethane (meth)acrylate compound (B-2) (functional group number: 6, weight average molecular weight: about 2000) was obtained.

<Synthesis of bifunctional urethane (meth)acrylate compound (B′)>
In a four-necked flask equipped with a thermometer, a stirrer, a water-cooled condenser, and a nitrogen gas blowing port, 29.9 g (0.14 mol) of isophorone diisocyanate, 54.2 g of polycarbonate diol (hydroxyl value 139.5 mgKOH/g; hydroxyl value) (Molecular weight calculated from 804; 0.07 mol) and 0.02 g of dibutyltin dilaurate as a reaction catalyst were charged and reacted at 60°C. When the residual isocyanate group became 6.7% or less, 15.9 g (0.14 mol) of 2-hydroxyethyl acrylate and 0.04 g of methoxyphenol as a polymerization inhibitor were further charged and reacted at 60° C. The reaction was terminated when the isocyanate group content was 0.3% or less, and a urethane (meth)acrylate compound (B′) (functional group number: 2, weight average molecular weight: about 5000) was obtained.

[Example 1]
As an acrylic monomer (A) having a biphenyl group, 69 parts of "A-LEN-10" manufactured by Shin-Nakamura Chemical Co., Ltd., as a 6-functional urethane (meth)acrylate compound, (B-1) 29 parts, photopolymerization start As an agent (C), 2 parts of "IRGACURE 184" manufactured by BASF Corp. was stirred and mixed in a flask, and the viscosity at 20°C was 1200 mPa.s. A photocurable composition [I-1] of s was obtained.
This was applied to an A4 size polycarbonate sheet “Panlite PC-1151 (thickness 500 μm)” manufactured by Teijin Ltd. with an applicator to obtain a photocurable composition layer having a thickness of 150 μm.
Further, a release agent-coated glass plate having irregularities of 1 mm pitch was placed on the photocurable composition layer, and the polycarbonate sheet was exposed to 250 mJ/cm ² with a UV irradiator (high pressure mercury lamp) and cured. After that, the glass plate was peeled off to obtain a laminate [II-1] in which the cured resin layer (hard coat layer) on which unevenness had been formed was laminated on one surface of the polycarbonate sheet.
Adhesion between the cured resin layer (hard coat layer) of the laminate [II-1] and the polycarbonate sheet was sufficient, and it was not peeled off with Cellotape (registered trademark). The refractive index of the cured resin layer was 1.58, and the pencil hardness of the cured resin layer was 3H. Further, the unevenness faithfully reproduced the glass type, and there was no problem in the fluidity and processability (2p processability) of the photocurable composition.

[ Reference Example 1 ]
The above (B-2) was used as the hexafunctional urethane (meth)acrylate compound. Otherwise in the same manner as in Example 1, the viscosity at 20° C. was 800 mPa.s. A photocurable composition [I-2] of s and a cured resin layer (hard coat layer) on which unevenness had been formed were laminated on one surface of a polycarbonate sheet to obtain a laminate [II-2].
The cured resin layer (hard coat layer) of the laminate [II-2] had a refractive index of 1.58, and the cured resin layer had a pencil hardness of 3H. Furthermore, the unevenness faithfully reproduced the glass mold, and there was no problem in the fluidity and processability (2p processability) of the resin composition.
Regarding the adhesive force between the cured resin layer (hard coat layer) of the laminate [II-2] and the polycarbonate sheet, there was a case where a piece of cellophane tape (registered trademark) was peeled off.

[Comparative Example 1]
A bifunctional urethane (meth)acrylate compound (B′) was used instead of the above (B-1). Otherwise in the same manner as in Example 1, the viscosity at 20° C. was 1200 mPa.s. A photocurable composition [I′-1] of s and a laminate [II′-1] were obtained.
The adhesive force between the cured resin layer of the laminate [II′-1] and the polycarbonate sheet was sufficient, and peeling did not occur with Cellotape (registered trademark). On the other hand, the cured resin layer had a refractive index of 1.58 and the cured resin layer had a pencil hardness of 3B, which was insufficient. The unevenness faithfully reproduced the glass mold, and there was no problem in the fluidity and processability (2p processability) of the resin.

[Comparative Example 2]
Instead of the above (A), an acrylic monomer having no biphenyl structure (“BPE-500” manufactured by Shin-Nakamura Chemical Co., Ltd.) was used. Otherwise in the same manner as in Example 1, the viscosity at 20° C. was 1200 mPa.s. A photocurable composition [I′-2] of s and a laminate [II′-2] were obtained.
Adhesion between the cured resin layer of the laminate [II′-2] and the polycarbonate sheet was sufficient, and peeling did not occur with Cellotape (registered trademark). On the other hand, the cured resin layer had a refractive index of 1.53, and the cured resin layer had a pencil hardness of B, which was insufficient. The unevenness faithfully reproduced the glass mold, and there was no problem in the fluidity and processability (2p processability) of the resin.

  In addition, each evaluation method in the said Example and a comparative example was performed as follows.

(Adhesion)
It was carried out with reference to the cross-cut method described in JIS K5600-5-6.
A 500 μm surface-untreated polycarbonate sheet was used as the substrate, and a UV-cured sample was used by coating the surface with the photocurable composition (coating agent). The coating amount at the time of coating and the UV irradiation amount at the time of curing were based on the conditions at the time of manufacturing the laminate of Examples and Comparative Examples. Then, the cross-cut to the cured resin layer made of the above coating agent was made by cutting 11 lines at 1 mm intervals with a cutter until reaching the base material in vertical and horizontal directions, and then, on the surface of the cured resin layer, cellophane tape (manufactured by Nichiban Co., Ltd. After applying (registered trademark), the peeling of the coating agent when peeled off quickly was visually observed.
○: It does not come off at all.
Δ: Part of the lattice is peeled off.
X: All the grids are peeled off.

(Pencil hardness)
It was carried out with reference to the scratch hardness test method described in JIS K5600-5-4.
A 500 μm surface-untreated polycarbonate sheet was used as the substrate, and a UV-cured sample was used by coating the surface with the photocurable composition (coating agent). The coating amount at the time of coating and the UV irradiation amount at the time of curing were based on the conditions at the time of manufacturing the laminate of Examples and Comparative Examples. Then, a pencil of each hardness was pressed against the surface of the cured resin layer made of the above coating agent at an angle of 45 degrees with a load of about 750 g, and was slid for 1 cm to observe scratches.

(Refractive index)
The refractive index of the cured resin layer of the photocurable composition (coated surface) was measured with a refractometer manufactured by Atago Co., Ltd. with reference to the plastic refractive index measurement method described in JIS K7142.

(Processability)
A 500 μm thick polycarbonate sheet was coated with a photocurable composition (coating agent) having a thickness of 150 μm, and a release agent-coated glass having irregularities with a pitch of 1 mm was covered thereon and irradiated with ultraviolet rays. Then, when the glass was peeled off, it was visually observed whether the unevenness of the surface of the cured resin layer (coat surface) of the photocurable composition reflected the unevenness of the glass.
○: It is completely reflected.
Δ: There is a defect that can be visually identified.
X: The unevenness is not reflected at all.

  Here, the results of the above-mentioned Examples and Comparative Examples are summarized as shown in Table 1 below.

From the results in Table 1 above, there was no evaluation of “x” in the adhesive strength and workability in both Examples and Comparative Examples. However, in Examples, the pencil hardness was further excellent and the refractive index was also high. On the other hand, in Comparative Example, the pencil hardness was obviously insufficient as compared with the cured resin layer in the laminate of Example, and in Comparative Example 2, the refractive index was also low. It was
From the above, the laminated body of the example showed excellent performance as a light guide plate, for example.

The invention is not limited to the above embodiment, having a biphenyl structure (meth) acrylic monomer (A), and ethylenically unsaturated groups possess four or more, urethanes have a carbonate structure (meth) acrylate compound (B It was confirmed by experiments that a photocurable composition containing) in a specific ratio can achieve both high pencil hardness and high refractive index, as in the above-mentioned Examples.

  Since the photocurable composition of the present invention is excellent in hard coat properties and has a high refractive index, it can be suitably used as a material for a light guide plate, a prism sheet, a diffusion plate or the like.

1 Base material sheet 2 Surface uneven layer

Claims (7)

Containing a (meth)acrylic monomer (A) having a biphenyl structure and a urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups ,
The urethane (meth)acrylate compound (B) having 4 or more ethylenically unsaturated groups is a urethane (meth)acrylate compound having a carbonate structure,
The content ratio (A/B) of the (meth)acrylic monomer (A) having a biphenyl structure and the urethane (meth)acrylate compound (B) having four or more ethylenically unsaturated groups is a weight ratio, A/B=50/50-90/10 The photocurable composition characterized by the above-mentioned. Urethane having an ethylenically unsaturated group 4 or more (meth) acrylate compound weight average molecular weight of (B) is, the photocurable composition of claim 1 Symbol mounting, characterized in that 1,000 to 20,000. The photocurable composition according to claim 1 or 2 , further comprising a photopolymerization initiator (C). The viscosity of the photocurable composition at 20 ° C., the photocurable composition according to any one of claims 1 to 3, characterized in that a 300~30000mPa · s. On at least one side of the substrate, the laminate cured resin layer comprising a photocurable composition according to any one of claims 1 to 4, characterized in that formed by laminating. The laminate according to claim 5, wherein the cured resin layer has an uneven structure on its surface. A light guide plate which is a laminate according to claim 5 or 6, wherein.

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