JP2007332169A - Photocurable resin composition and optical functional sheet obtained by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable resin composition which allows formation of an optical functional sheet having a fine pattern and can sufficiently satisfy adhesion with a sheet substrate, mold-release properties with a die, surface hardness of a processed layer, and flexibility/scratch resistance of a sheet, and to provide the optical functional sheet. <P>SOLUTION: The photocurable resin composition comprises a specific urethane (meth)acrylate represented by general formula (4) obtained by reacting a specific organic isocyanate compound which contains at least two isocyanate groups in a molecule and is represented by general formula (1), a specific compound which contains at least three active hydrogens in a molecule and is represented by general formula (2), wherein the specific compound excludes a compound which contains three active hydrogens in a molecule but does not contain a cyclic structure, and a specific (meth)acrylate containing a hydroxy group represented general formula (3). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photocurable resin composition, a curable resin composition, and an optical functional sheet, which are excellent in fine pattern-forming properties, and have excellent adhesion to a sheet substrate and excellent releasability from a mold. is there.

  Conventionally, photocurable resin compositions containing various acrylate monomers have been proposed in the production of optical functional sheets represented by lens sheets and prism sheets. Physical properties required for these photocurable resin compositions include viscosity suitable for production, curing speed, surface hardness after curing, flexibility, adhesion to sheet-like substrate, and external force applied to pattern shape. It is necessary to satisfy various requirements, such as the resilience when it is applied.

As a method for satisfying these physical properties, for example, in order to improve the scratch resistance of the surface processed layer, studies have been made to increase the elasticity of the processed layer and to provide a restoring property (Patent Documents 1 to 8).
JP 2000-344845 A JP 2002-105149 A JP 2003-277451 A JP 2004-131520 A JP-A-2005-23194 JP 2005-68331 A JP 2005-272700 A JP 2003-302501 A

However, such conventional polyfunctional, particularly tri- or higher functional urethane (meth) acrylate-containing photocurable resin compositions, for example, hydroxyl group-containing polyfunctional (meth) acrylates typified by bifunctional diisocyanate and pentaerythritol triacrylate. Urethane obtained by reacting a compound containing a hydroxyl group-containing (meth) acrylate and a urethane (meth) acrylate obtained by reacting a compound containing a trifunctional isocyanate compound obtained by reacting a bifunctional isocyanate compound with an isocyanurate or biuret. A photocurable resin composition containing (meth) acrylate is known, but sufficient physical properties were not obtained. That is, in the former, since the cross-linking group is localized due to the linear structure, the hardness and flexibility are opposite to each other, and in the latter, since structural freedom is low, it gives resilience and flexibility, There are very few means to obtain the desired physical properties such as reduced surface hardness, adhesion to the sheet base material, mold releasability, surface hardness of the processed layer and flexibility / abrasion resistance of the sheet. A sufficiently satisfactory cured product was not obtained.
In view of the background of such prior art, the present invention makes it possible to form an optical functional sheet having a fine pattern, adhesion to a sheet base material, releasability from a mold, surface hardness of a processed layer and the sheet. It is an object of the present invention to provide a photocurable resin composition and an optical functional sheet that can sufficiently satisfy flexibility and scratch resistance.

  The present invention employs the following means in order to solve such problems. That is, the photocurable resin composition of the present invention includes an organic isocyanate compound containing at least two isocyanate groups in one molecule represented by the following general formula (1), and 1 represented by the following general formula (2). A compound containing at least 3 active hydrogens in the molecule (excluding a compound containing 3 active hydrogens per molecule but not containing a cyclic structure), and a hydroxyl group represented by the following general formula (3): A photocurable resin composition comprising a urethane (meth) acrylate represented by the following general formula (4) obtained by reacting with (meth) acrylate.

  In the formula, R1 and R2 are compounds containing an aliphatic, alicyclic, aromatic ring-substituted aliphatic, aromatic or heterocyclic structure, R3 is aliphatic, alicyclic, aromatic ring-substituted aliphatic, aromatic or R4 is a hydrogen atom or a methyl group, a compound containing a structure such as a heterocyclic ring, a polyether chain, or a polyester chain. When the X atom is O or S, a = 1, and when the X atom is N, a = 2. l is 3-25. b is 0-10. m is an arbitrary value of 1 or more. n is a value smaller than l.

  The optical functional sheet of the present invention is characterized in that such a photocurable resin composition is applied to a sheet-like substrate and cured.

  According to the present invention, it is possible to form an optical functional sheet having a fine pattern, adhesion to a sheet base material, releasability from a mold, surface hardness of a processed layer and flexibility / abrasion resistance of the sheet. Can be obtained.

  The present invention makes it possible to form the above-mentioned problem, that is, an optical functional sheet having a fine pattern, adhesion to a sheet base material, releasability from a mold, surface hardness of a processed layer and flexibility / resistance of the sheet. With regard to the photo-curable resin composition that can sufficiently satisfy the scratch resistance, the inventors have intensively studied and selected three kinds of a specific organic isocyanate compound, a specific polyvalent active hydrogen compound, and a hydroxyl group-containing (meth) acrylate). As a result of the reaction, it was found that urethane (meth) acrylate having a special structure in which (meth) acrylate groups spread three-dimensionally radially was obtained, and light with urethane (meth) acrylate having such a special structure was obtained. When a curable resin composition is constituted, the photocurable resin composition has a very high degree of structural freedom, so that it is easy to adjust desired physical properties and further improve conventional physical properties. Rukoto also became possible. In addition, by creating a cured product using the photocurable resin composition, adhesion to a sheet-like substrate, mold releasability, surface hardness of the processed layer and flexibility / abrasion resistance of the sheet It has been found that an optical functional sheet satisfying the above can be obtained.

  The urethane (meth) acrylate component having a structure in which the (meth) acrylate group spreads in a three-dimensional radial pattern used in the photocurable resin composition of the present invention is contained in one molecule represented by the following general formula (1). An organic isocyanate compound containing at least two or more isocyanate groups, and a compound containing at least three or more active hydrogens in one molecule represented by the following general formula (2) (provided that three active hydrogens are contained in one molecule) Is a three-dimensional radial form represented by the following general formula (4) obtained by reacting a hydroxyl group-containing (meth) acrylate represented by the following general formula (3). This is a urethane (meth) acrylate having a structure in which a (meth) acrylate group is spread.

  In the formula, R1 and R2 are compounds containing an aliphatic, alicyclic, aromatic ring-substituted aliphatic, aromatic or heterocyclic structure, R3 is aliphatic, alicyclic, aromatic ring-substituted aliphatic, aromatic or R4 is a hydrogen atom or a methyl group, a compound containing a structure such as a heterocyclic ring, a polyether chain, or a polyester chain. When the X atom is O or S, a = 1, and when the X atom is N, a = 2. l is 3 to 25, and preferably 3 to 18. b is 0-10, and it is preferable that it is 0-1. m is an arbitrary value of 1 or more, and is preferably 1 to 3. n is a value smaller than l.

  The structure of R1 to R4 in the formula can be selected as a molecular structure in order to adjust desired physical properties such as flexibility, surface hardness, and scratch resistance. Increasing the values of l and m can be expected to improve photocurability and surface hardness by increasing the (meth) acrylate groups, and increasing the value of n increases the adhesion of polar groups. Can be expected.

  Hereinafter, each component used for production of urethane (meth) acrylate will be described.

  The organic isocyanate compound containing two or more isocyanate groups in the molecule will be described. Examples of such a compound include, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene- 1,4-diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxybiphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1 , 3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4′-diphenylpropane diisocyanate, 4,4′-diphenylhexafluoropropa Diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4 -Diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane and 1,3-bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, norbornane diisocyanate and the like.

  Furthermore, trifunctional or higher functional organic isocyanate compounds can also be used. Examples of such compounds are the aforementioned bifunctional isocyanate compounds as main raw materials, their trimers (burette or isocyanurate), formalin condensates of benzene isocyanate, polymerizable groups such as (meth) acryloyloxyethyl isocyanate. Polymeric lysine triisocyanate of an isocyanate compound having a hydrogen atom can also be used.

  These polyfunctional isocyanates may be used alone or in combination of two or more.

  A compound having 3 or more active hydrogens in the molecule (excluding compounds having no cyclic structure having 3 active hydrogens in one molecule) will be described. Examples of the functional group having active hydrogen include a hydroxyl group, an amino group, a carboxyl group, and a mercapto group. Of these, a hydroxyl group is particularly preferred. Examples of such compounds include alcohol compounds having a cyclic structure having three hydroxyl groups in the molecule, such as 1,2,3-trihydroxycyclohexane, 1,2,4-trihydroxycyclohexane, 1,3,5. -Trihydroxycyclohexane, tris (2-hydroxyethyl) isocyanurate, 1,3,5- (trihydroxyethyl) tolidine and the like. In the case of a compound having three active hydrogens not having a cyclic structure, flexibility is obtained, but surface hardness may be insufficient.

  Further, phenols having three hydroxyl groups include 1,3,5-trihydroxybenzene, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, 2,4,6-trihydroxybenzoate. Acids and 2,4,6-trihydroxybenzoic acid derivatives, gallic acid and gallic acid derivatives, 2,4,5-trihydroxypyrimidine, 2 ', 3', 4'-trihydroxyacetophenone, 2 ', 4', 6'-trihydroxyacetophenone, 4 ', 5,7-trihydroxyflavone and the like can be mentioned.

  Further, polyol compounds and polyphenol compounds having 4 or more hydroxyl groups include 1,2,4,5-tetrahydroxycyclohexane, 1,2,5,6-tetrahydroxycyclooctane, 2,3,4,4′-tetra. Hydroxydiphenylmethane, ellagic acid, 3,7,3 ′, 4′-tetrahydroxyflavone, 6,6 ′, 7,7′-tetrahydroxy-4,4,4 ′, 4′-tetramethyl-2,2 ′ -Spirobichroman, 5,5 ', 6,6'-tetrahydroxy-3,3,3', 3'-tetramethyl-1,1'-spirobiindane and D-(+)-glucose, D-mannitol, Examples thereof include saccharides typified by D-sorbitol and derivatives thereof, but it is not limited thereto.

  The hydroxyl group-containing (meth) acrylate will be described. Examples of such compounds include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4- Hydroxybutyl acrylate, tris (2-hydroxyethyl) isocyanurate diacrylate, glycerol diacrylate, glycerol dimethacrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polytetramethylene glycol mono (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid glycerin monomethacrylate, 3-acryloyloxyglycerin monomethacrylate, penta Erythritol tri (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolmethane di (meth) acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, terminal (Meth) acrylate having at least one hydroxyl group in the molecule, such as hydroxyl group polyester mono (meth) acrylate, is of course not limited thereto.

  In the production of the component urethane (meth) acrylate, the formation of a urethane bond is typically represented by copper naphthenate, cobalt naphthenate, zinc naphthenate, di-n-butyltin dilaurate, and stannous octylate. It is preferable to use 0.01 to 1% by weight of a urethanization catalyst such as an amine catalyst such as a tin catalyst, triethylamine or diaminobicyclooctene based on the total amount of reaction raw materials. In addition, reaction temperature is 10-90 degreeC normally, Especially 30-80 degreeC is preferable.

  The number average molecular weight of urethane (meth) acrylate is preferably 1000 to 30000, and particularly preferably 1500 to 15000. When the number average molecular weight of the component (A) urethane (meth) acrylate is less than 1000, the elastic modulus of the cured product obtained by curing the resin composition is increased, and when a desired pattern is formed, If the number average molecular weight exceeds 30000, the viscosity of the resin composition becomes very high and the workability tends to be lowered.

  A method for synthesizing urethane (meth) acrylate obtained by reacting a compound containing the above three components of organic isocyanate, polyvalent active hydrogen compound and hydroxyl group-containing (meth) acrylate will be described. Although there is no restriction | limiting in particular about a synthesis method, For example, a polyvalent isocyanate compound is synthesize | combined by making an organic isocyanate and a polyvalent active hydrogen compound react, and also this polyvalent isocyanate compound and a hydroxyl-containing (meth) acrylate are made to react. And urethane (meth) acrylate can be obtained.

  In the case of this synthesis method, the equivalent of the organic isocyanate to the polyvalent active hydrogen compound is preferably more than 3 equivalents and 10 equivalents or less, more preferably 6 equivalents or less.

  If it is 3 equivalents or less, the reaction mixture may gel or harden depending on the reaction conditions. If it exceeds 10 equivalents, the hydroxyl group-containing (meth) acrylate and unreacted organic isocyanate react to form a linear urethane ( As the content of (meth) acrylate increases, the surface hardness may decrease.

  As another synthesis method, for example, an isocyanate (meth) acrylate is synthesized by reacting an organic isocyanate and a hydroxyl group-containing (meth) acrylate, and further urethane (by reacting the isocyanate (meth) acrylate with a polyvalent active hydrogen compound). A (meth) acrylate can be obtained.

  In the case of this synthesis method, the equivalent of the organic isocyanate to the hydroxyl group-containing (meth) acrylate is preferably 0.8 equivalents or more and 1.2 equivalents or less, and preferably 0.9 equivalents or more and 1.1 equivalents or less. Further preferred. When the equivalent of the organic isocyanate is less than the lower limit, a bifunctional urethane (meth) acrylate is produced, and the reaction with the polyvalent active hydrogen compound is difficult to proceed. When more than an upper limit, unreacted organic isocyanate remains.

  The equivalent of the hydroxyl group-containing (meth) acrylate with respect to the active hydrogen group of the polyvalent active hydrogen compound is preferably 0.1 equivalent or more and 1.1 equivalent or less, and 0.3 equivalent or more and 1.05 equivalent or less. More preferably it is. If the equivalent is less than the lower limit, the content of the (meth) acrylate moiety relative to the urethane (meth) acrylate is small, and sufficient surface hardness may not be obtained. When it exceeds the upper limit, unreacted isocyanate (meth) acrylate remains.

  The urethane (meth) acrylate is preferably contained in the total resin composition in an amount of 10 to 90% by weight, more preferably 20 to 80% by weight. When the content is below the lower limit of the numerical range, flexibility is imparted to the cured product, while scratch resistance and surface hardness are reduced. Moreover, when content exceeds the upper limit of the said numerical range, since a viscosity will rise and workability | operativity will fall, it is preferable that it is the said range.

  In the present invention, in addition to the above components, other monofunctional and polyfunctional monomers, oligomers, and polymers that are curable can be added as long as they do not impair the properties of the resin composition of the present invention. As such a compound, for example, as a monofunctional (meth) acrylate monomer, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-hexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, Butoxyethyl (meth) acrylate, allyl (meth) acrylate, glycidyl (meth) acrylate, methallyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N , N-Diethylaminoethyl (meth) acryle N, N-diethylaminopropyl (meth) acrylate, polyethylene glycol monoalkyl ether (meth) acrylate, polypropylene glycol monoalkyl ether (meth) acrylate, acryloylmorpholine, styrene, N-vinylpyrrolidone, phenyl (meth) acrylate, Benzyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, phenoxyethyl ( (Meth) acrylate, phenoxy-2-methylethyl (meth) acrylate, phenoxyethoxyethyl (meth) acrylate, 3-phenoxy-2- Droxypropyl (meth) acrylate, 2-phenylphenoxyethyl (meth) acrylate, 4-phenylphenoxyethyl (meth) acrylate, 3- (2-phenylphenyl) -2-hydroxypropyl (meth) acrylate, ethylene oxide modified p- Examples include (meth) acrylate of cumylphenol, 2-bromophenoxyethyl (meth) acrylate, 2,4-dibromophenoxyethyl (meth) acrylate, 2,4,6-tribromophenoxyethyl (meth) acrylate, and the like.

  Examples of the polyfunctional (meth) acrylate monomer include 1,6-hexane diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol hydroxypivalate ester diacrylate, neopentyl glycol modified trimethylolpropane diacrylate, hydroxy Caprolactone-modified diacrylate of pivalic acid neopentyl glycol ester, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, bisphenol A di (meth) acrylate, ethylene oxide modified bisphenol A (meth) acrylate, propylene oxide modified Bisphenol A (meth) acrylate, bisphenol Epoxy (meth) acrylate obtained by reaction of diol A and glycidyl (meth) acrylate, epoxy (meth) acrylate obtained by reaction of ethylene oxide-modified bisphenol A and glycidyl (meth) acrylate, propylene oxide-modified bisphenol A and glycidyl ( Epoxy (meth) acrylate obtained by reaction with (meth) acrylate, tris [2- (acryloyloxy) ethyl] isocyanurate, tris [2- (acryloyloxy) propyl] isocyanurate, 2,4,6-tris (acryloyl) Oxyethoxy) -1,3,5-triazine, 2,4,6-tris (acryloyloxypropoxy) -1,3,5-triazine and the like.

  The photopolymerization initiator preferably used in the present invention is not particularly limited as long as it matches the wavelength of the electromagnetic wave to be irradiated and the electromagnetic wave is decomposed by irradiation to generate radicals to start polymerization. 2,2-dimethoxy-1,2-diphenylethane-1-one, p-tert-butyltrichloroacetophenone, 2,2′-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1- Acetophenones such as ON, ketones such as benzophenone, 4,4′-bisaminodimethylbenzophenone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzoin , Benzoin methyl ether, benzoin isopropyl Ether, benzoin ethers such as benzoin isobutyl ether, benzyl dimethyl ketal, benzil ketals, such as hydroxycyclohexyl phenyl ketone.

  A photosensitizer can be added to the photopolymerization initiator as necessary. Examples of the photosensitizer include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and 4-dimethylaminobenzoic acid. Examples include isoamyl.

  Moreover, various additives can be added to the photocurable resin composition of the present invention within a range where the effects of the present invention are not lost. Examples of additives to be added and blended include fillers such as inorganic fine particles, dyes, fluorescent whitening agents, antioxidants, anti-molding agents, antistatic agents, polymerization inhibitors, mold release agents, thickeners and the like. It is done. In the photocurable resin composition, the total of the additives preferably accounts for 30% by weight, more preferably 20% by weight, and even more preferably 10% by weight or less. If the upper limit of the numerical range is exceeded, sufficient physical properties cannot be obtained.

  You may add a solvent to the photocurable resin composition of this invention. Examples of solvents include aromatic hydrocarbon solvents such as toluene and xylene, alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butanol and isobutanol, and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. And ester solvents such as ethyl acetate, propyl acetate, and butyl acetate.

The cure shrinkage ratio of the photocurable resin composition containing urethane (meth) acrylate having a structure in which the (meth) acrylate group spreads radially in the three-dimensional radial form of the present invention is the specific gravity of the photocurable resin composition at 25 ° C. The specific gravity at 25 ° C. of the photocurable resin composition after photoirradiation curing was measured and calculated based on the following formula.
Curing shrinkage (%) = (d (after curing) −d (before curing)) / d (after curing) × 100
d (Before curing): Specific gravity at 25 ° C. of photocurable resin composition d (After curing): Specific gravity at 25 ° C. after photoirradiation curing of the photocurable resin composition.

  It is preferable that the cure shrinkage rate at 25 ° C. of the photocurable resin composition is 7.5% or less. If the curing shrinkage is greater than 7.5%, the optical functional sheet obtained by applying the photocurable resin composition to the substrate sheet and curing may be warped.

  The viscosity of the photocurable resin composition containing urethane (meth) acrylate having a structure in which the (meth) acrylate group spreads radially in the three-dimensional radial form of the present invention is not particularly limited, but the viscosity at 25 ° C. is usually 70 to It is preferably 30000 mPa · s, particularly 100 to 20000 mPa · s. When the viscosity exceeds the upper limit, it becomes difficult to fill the resin composition up to the details of the mold and it becomes easy to bite bubbles. When the viscosity is smaller than the lower limit, the fluidity of the resin composition increases, which may cause thickness unevenness during pattern formation.

In the production of an optical functional sheet, wherein the photocurable resin composition of the present invention is applied to a sheet-like substrate and cured, the light irradiation light source is not particularly limited, but includes a low pressure mercury lamp, a high pressure Mercury lamps, xenon lamps, chemical lamps, electron beams, sunlight, etc. can be used. Irradiation energy is not particularly limited. For example, in the case of ultraviolet rays, it is preferable to irradiate such that the integrated energy at a wavelength of 200 to 600 nm is 100 to 5000 mJ / cm ² .

  The cured product of the photocurable resin composition of the present invention preferably has a surface hardness of HB or higher, more preferably 2H or higher, in the pencil hardness measurement according to the method of JIS K5600. If the surface hardness is smaller than HB, the surface pattern is likely to be damaged during manufacture or transportation, and the surface pattern may be damaged.

  Even if the optical functional sheet obtained by curing the photocurable resin composition of the present invention is bent 180 ° along a cylinder having a diameter of 5 mm, more preferably 1 mm, in a bending test according to JIS K5600, the photocurable resin composition is obtained. It is preferred that the hardened surface does not break. If it breaks on the said conditions, the softness | flexibility of the cured film which the resin composition hardened | cured will become scarce, and a restoring property may fall.

  When the optical functional sheet obtained by curing the photocurable resin composition of the present invention is cut into a 10 cm square and exposed under conditions of a temperature of 80 ° C. and a humidity of 60% for 8 hours, then returned to room temperature and placed on a flat surface. In the measurement of the warp height of the four sides from the plane, it is preferable that the warp height of the four sides is 4 mm or less. If this condition is not satisfied, the sheet may be warped or distorted at high temperatures.

  In the cross-cut test in which the optical functional sheet obtained by curing the photocurable resin composition of the present invention is measured based on JIS K5600, the cured photocurable resin composition layer peeled at 10/100 or less. Some are preferred.

  Synthesis examples and examples are shown below, but the present invention is not limited thereto. In the synthesis examples and examples, “parts” are all parts by weight.

(Evaluation items and evaluation methods)
The following evaluation was performed about the obtained photocurable resin composition and optical functional sheet.

(1) Curing shrinkage: The specific gravity of the photocurable resin before and after curing at 25 ° C. was measured, and the curing shrinkage was determined from the change in specific gravity based on the following formula, and evaluated according to the following criteria.
Curing shrinkage (%) = (d (after curing) −d (before curing)) / d (after curing) × 100
d (before curing): specific gravity at 25 ° C. of the photocurable resin composition d (after curing): specific gravity at 25 ° C. after photoirradiation curing of the photocurable resin composition ◎: cure shrinkage ratio is 5% or less Good ○: Curing shrinkage greater than 5%, 7.5% or less x: Curing shrinkage greater than 7.5%

(2) Releasability: The degree of difficulty when releasing the cured product from the mold was evaluated according to the following criteria.
◎: Can be released from the mold without resistance ○: Can be released from the mold with some resistance △: Can be released from the mold is slightly difficult ×: Release from the mold Is difficult or the resin remains in the mold.

(3) Adhesiveness: A cross-cut test was conducted in accordance with JIS K5600 Part 5-Section 6 (established in 1999). The adhesion was evaluated according to the following criteria.
：: peeling is 0/100 ○: peeling is 1/100 to 10/100 or less Δ: peeling is 10/100 to 50/100 ×: peeling is 50/100 or more

(4) Pencil hardness: Pencil hardness was measured according to JIS K5600 Part 5-Section 4 (established in 1999) and evaluated according to the following criteria.
A: Hardness of 2H or more B: Hardness of HB or more and H or less x: Hardness of softer than HB

(5) Flexibility: In accordance with JIS K5600 Part 5-Section 1 (established in 1999), the optical functional sheet is wound around a cylinder, and the flexibility is judged from the breaking state of the optical functional layer, and evaluated according to the following criteria. did.
○: A cylinder with a diameter of 1 mm that does not break, etc. Δ: A cylinder with a diameter of 1 mm breaks, but a cylinder with a diameter of 5 mm does not break, etc. x: A cylinder with a diameter of 5 mm breaks.

(6) Dimensional stability: After the optical functional sheet cut to 10 cm square is heated with a dryer at a temperature of 80 ° C. and a humidity of 60% for 8 hours and then placed on a flat surface at 25 ° C., the warpage height of the four sides from the flat surface The thickness was measured and evaluated according to the following criteria.
◎: The total warp height of the four sides is 2 mm or less. ○: The total warp height of the four sides is greater than 2 mm and less than 4 mm. Δ: The total warp height of the four sides is greater than 4 mm and less than 8 mm. X: The total of the warp heights of the four sides exceeds 8 mm.
(7) Workability: Workability when drawing the photocurable resin composition into a prism mold was evaluated according to the following criteria.
○: Good viscosity and good workability ×: High viscosity, easy to entrain air bubbles and difficult to work.

(Synthesis Example 1)
Add 69.6 parts of 2,4-toluene diisocyanate, 12.6 parts of pyrogallol, and 0.5 parts of stannous octylate. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 32.5 parts of 2-hydroxypropyl acrylate and 62.0 parts of tetraethylene glycol monoacrylate were added and held at 50 ° C. for 5 hours to obtain urethane acrylate UA-1.

(Synthesis Example 2)
Add 69.6 parts of 2,4-toluene diisocyanate, 13.2 parts of 1,2,3-trihydroxycyclohexane, and 0.5 parts of stannous octylate. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 178.5 parts of nonapropylene glycol monoacrylate and 40.0 parts of glycerin diacrylate were added and kept at 50 ° C. for 5 hours to obtain urethane acrylate UA-2.

(Synthesis Example 3)
Add 88.8 parts isophorone diisocyanate, 13.2 parts 1,3,5-trihydroxybenzene, and 0.5 parts stannous octylate. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 44.4 parts of 2-hydroxy-3-phenoxypropyl acrylate and 130.5 parts of hexapropylene glycol monomethacrylate were added and held at 50 ° C. for 5 hours to obtain urethane acrylate UA-3.

(Synthesis Example 4)
Add 17.4 parts 2,4-toluene diisocyanate, 50.4 parts hexamethylene diisocyanate, 12.6 parts pyrogallol, and 0.5 parts stannous octylate. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 65.0 parts of 2-hydroxypropyl acrylate was added and maintained at 50 ° C. for 5 hours to obtain urethane acrylate UA-4.

(Synthesis Example 5)
Add 69.6 parts of 2,4-toluene diisocyanate, 40.8 parts of triethylene glycol monoacrylate, 121.8 parts of nonapropylene glycol monomethacrylate, and 1.0 part of stannous octylate. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 18.0 parts of D-(+)-glucose was added and maintained at 50 ° C. for 8 hours to obtain urethane acrylate UA-5.

(Synthesis Example 6)
Toluene diisocyanate 43.5 parts, hexamethylene diisocyanate 42.0 parts, 2-hydroxyethyl acrylate caprolactone 2-mole adduct 103.3 parts, 2-hydroxyethyl acrylate 23.2 parts and stannous octylate 0.5 parts Add. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 18.2 parts of D-mannitol was added and maintained at 50 ° C. for 8 hours to obtain urethane acrylate UA-6.

(Synthesis Example 7)
34.8 parts of toluene diisocyanate, 120 parts of polytetramethylene glycol (number average molecular weight 1200), and 0.5 part of stannous octylate are added. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 59.6 parts of pentaerythritol triacrylate was added and kept at 50 ° C. for 5 hours to obtain urethane acrylate UA-7.

(Synthesis Example 8)
50.5 parts of an isocyanurate-modified product of hexamethylene diisocyanate, 103.3 parts of 2-hydroxyethyl acrylate caprolactone 2 mol adduct and 0.5 parts of stannous octylate are added. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 5 hours to obtain urethane acrylate UA-8.

(Synthesis Example 9)
Add 69.6 parts of toluene diisocyanate, 13.4 parts of trimethylolpropane, and 0.5 part of stannous octylate. It was kept at room temperature for 1 hour, further heated to 50 ° C. and kept for 3 hours. To this reaction mixture, 58.0 parts of 2-hydroxyethyl acrylate was added and maintained at 50 ° C. for 5 hours to obtain urethane acrylate UA-9.

(Examples 1-6, Comparative Examples 1-4)
At 25 ° C., the photocurable resin and the initiator were mixed well in the composition shown in Table 2 to obtain a uniform solution to obtain a photocurable resin composition.

The obtained photocurable resin composition was applied to a 100 μm thick polyethylene terephthalate film (Lumirror (registered trademark) 100U42: manufactured by Toray Industries, Inc.) with a coating thickness of 30 μm. Then, the sheet | seat was manufactured by 1000 mJ / cm < ² > irradiation using the ultra high pressure mercury lamp.

In order to examine releasability and workability, a photocurable resin is poured into a prism mold having a pitch of 50 μm and an apex angle of 90 degrees, and a polyethylene terephthalate film and a mold are attached from the end of the mold by a hand roller. In addition, an optical functional sheet was manufactured by irradiating with 1000 mJ / cm ² using an ultrahigh pressure mercury lamp and peeling from the mold.

However, the meanings of the symbols in Table 1 are as follows.
PA-1: Bisphenol A ethylene oxide 4 mol addition diacrylate PA-2: Triethylene glycol diacrylate PA-3: Dipentaerythritol hexaacrylate MA-1: Benzyl methacrylate MA-2: Phenoxyethyl acrylate MA-3: Isobornyl Acrylate MA-4: Tetrahydrofurfuryl acrylate MA-5: 2-hydroxyethyl acrylate PI-1: Irgacure 184 (manufactured by Ciba Specialty Chemicals)
PI-2: Darocur 1173 (manufactured by Ciba Specialty Chemicals).

  As shown in Table 2, the photocurable resin compositions obtained in Examples 1 to 6 were excellent in workability for injection into a prism mold, and the photocurable resin composition was applied to a sheet-like substrate. The optically functional sheet obtained by curing sufficiently satisfies the adhesion to the sheet base material, the mold releasability, the surface hardness of the processed layer, and the flexibility and scratch resistance of the sheet. there were.

  On the other hand, in the photocurable resin composition containing the urethane (meth) acrylate of Comparative Examples 1 to 3, the surface hardness was poor. Moreover, in the photocurable resin composition of the comparative example 4, cure shrinkage, a softness | flexibility, and adhesiveness with a sheet | seat base material were inferior.

Claims (7)

An organic isocyanate compound containing at least two or more isocyanate groups in one molecule represented by the following general formula (1), and a compound containing at least three or more active hydrogens in one molecule represented by the following general formula (2) (However, a compound containing three active hydrogens in one molecule but excluding a cyclic structure is excluded) obtained by reacting a (meth) acrylate containing a hydroxyl group represented by the following general formula (3) A photocurable resin composition comprising a urethane (meth) acrylate represented by the general formula (4).

In the formula, R1 and R2 are compounds containing an aliphatic, alicyclic, aromatic ring-substituted aliphatic, aromatic or heterocyclic structure, R3 is aliphatic, alicyclic, aromatic ring-substituted aliphatic, aromatic or R4 is a hydrogen atom or a methyl group, a compound containing a structure such as a heterocyclic ring, a polyether chain, or a polyester chain. When the X atom is O or S, a = 1, and when the X atom is N, a = 2. l is 3-25. b is 0-10. m is an arbitrary value of 1 or more. n is a value smaller than l.   2. The photocurable resin composition according to claim 1, wherein the photocurable resin composition has a cure shrinkage of 7.5% or less as measured by a method defined in the specification. .   An optical functional sheet obtained by applying the photocurable resin composition according to claim 1 or 2 to a sheet-like substrate and curing the composition.   4. The optical functional sheet according to claim 3, wherein the cured photocurable resin composition has a surface hardness measured based on JIS K5600 of not less than HB in pencil hardness.   The optical functional sheet has a bending rate measured based on JIS K5600, and the surface on which the photocurable resin composition is cured does not break even if it is bent 180 ° along a cylinder having a diameter of 5 mm. The optical functional sheet according to claim 3 or 4, wherein the optical functional sheet is characterized in that: The optical functional sheet according to any one of claims 3 to 5, wherein the optical functional sheet has a dimensional stability defined below of 4 mm or less.
Dimensional stability: The test piece obtained by cutting an optical functional sheet into a 10 cm square was measured for the warp height of the four sides of the test piece when left at 80 ° C. for 8 hours.   The optically functional sheet is characterized in that, in a cross-cut test measured based on JIS K5600, peeling of the cured photocurable resin composition layer is 10/100 or less. The optical functional sheet according to any one of 3 to 6.