JP2012116923A - Ultraviolet-curing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet-curing resin composition which gives a cured product in which the cured product obtained maintains scratch resistance, and warpage is small, and which is excellent in resin adhesion after wet heat treatment, and transparency.SOLUTION: The ultraviolet-curing resin composition includes: a two functional urethane (meth)acrylate (A) which is obtained by making a polyether polyol (a) which has an oxyalkylene chain in a molecule and whose number-average molecular weight is 300-2,000, an organic polyisocyanate (b), and a hydroxy group containing (meth)acrylate (c) react mutually; a multi-functional (meth)acrylate (B) in which a number of functional groups is 3-5; a monofunctional (meth)acrylate (C) which contains an aromatic ring in a molecule; and a photopolymerization initiator (D).

Description

The present invention relates to an ultraviolet curable resin composition.
More specifically, the present invention relates to an ultraviolet curable resin composition such as an optical film having small warpage and excellent in scratch resistance, resin adhesion after wet heat treatment, and transparency, and an optical film formed by curing it.

Conventionally, optical lenses such as prism sheets used in liquid crystal displays, Fresnel lenses and lenticular lenses used in projection televisions have been generally manufactured by injection molding of thermoplastic resin or hot press molding. . These manufacturing methods have a problem that productivity is low because a long time is required for heating and cooling during manufacturing, and reproducibility of the fine structure is poor due to thermal contraction of the optical lens.
Therefore, in order to solve these problems, a method in which an ultraviolet curable resin composition is poured into a mold in which a transparent resin base material is set on the inner surface of the mold and is cured by irradiating with ultraviolet rays is subsequently implemented. .

In recent years, with the thinning of displays, it has been studied to reduce the thickness of optical films such as diffusion films, brightness enhancement films, and prism lenses.
However, thinned optical films are easily damaged when they come into contact with each other at the time of transportation. Therefore, prevention thereof has been studied. For example, a method of introducing a rigid structure such as a bisphenol skeleton (Patent Document 1), a polyfunctional acrylate A method (Patent Document 2) and the like for introducing the method are proposed.

JP-A-11-240926 JP 2004-131520 A

However, the method of Patent Document 1 has a problem that the scratch resistance is insufficient.
In addition, since the method of Patent Document 2 uses hexafunctional acrylate, the acryloyl group content is high, and curing shrinkage during ultraviolet curing increases. In general, the higher the acryloyl group content, the greater the shrinkage of curing, resulting in the problem of warping of the film. Further, when a hexafunctional acrylate having a large cure shrinkage is used, there is a problem that the resin adhesion after the wet heat treatment is deteriorated.

An object of the present invention is to provide an ultraviolet curable resin composition that gives a cured product having small warpage and excellent in resin adhesion and transparency after wet heat treatment while maintaining scratch resistance.

The inventor of the present invention has arrived at the present invention as a result of studies to achieve the above object.
That is, in the present invention, a polyether polyol (a) having a number average molecular weight of 300 to 2,000 having an oxyalkylene chain in the molecule, an organic polyisocyanate (b), and a hydroxyl group-containing (meth) acrylate (c) are reacted. Bifunctional urethane (meth) acrylate (A), polyfunctional (meth) acrylate (B) having 3 to 5 functional groups, monofunctional (meth) acrylate (C) containing an aromatic ring in the molecule, and light An ultraviolet curable resin composition containing a polymerization initiator (D); a cured product for an optical member obtained by curing the ultraviolet curable resin composition by ultraviolet irradiation.

  Although the ultraviolet curable resin composition of the present invention has scratch resistance, the warpage is small, and the resin adhesiveness and transparency after wet heat treatment are excellent.

The ultraviolet curable resin composition of the present invention comprises a bifunctional urethane (meth) acrylate (A) having a specific chemical structure, a polyfunctional (meth) acrylate (B) having 3 to 5 functional groups, and an aromatic ring in the molecule. The monofunctional (meth) acrylate (C) and photopolymerization initiator (D) to be contained are essential components.
The bifunctional urethane (meth) acrylate (A) in the present invention is a polyether polyol (a), an organic polyisocyanate (b) and a hydroxyl group having an oxyalkylene chain in the molecule and a number average molecular weight of 300 to 2,000. It is comprised from the containing (meth) acrylate (c).

The bifunctional urethane (meth) acrylate (A), which is the first essential component in the present invention, is particularly limited as long as it is a urethane compound having a polyether polyol skeleton in the molecule and containing a (meth) acryloyl group. The urethane (meth) acrylate formed from the urethanization reaction of the urethane prepolymer (d) having an isocyanate group and the hydroxyl group-containing (meth) acrylate (c) is preferred.

The urethane prepolymer (d) having an isocyanate group is obtained by reacting a polyether polyol (a) having a number average molecular weight of 300 to 2,000 and an organic polyisocyanate (b), and (a) and The molar ratio (a) / (b) of (b) is usually 1/3 to 10/1, preferably 1/2 to 8/1. Within this range, low shrinkage is excellent while still having scratch resistance.
The OH / NCO equivalent ratio in the reaction of (a), (b) and (c) is usually 0.45 to 0.99, preferably 0.50 to 0.97.

The polyether polyol (a), which is a raw material of the urethane prepolymer (d), is number average molecular weight [hereinafter abbreviated as Mn] from the viewpoint of scratch resistance and low curing shrinkage. The measurement is based on a gel permeation chromatography (GPC) method. ] Is preferably 300 to 2,000, more preferably 500 to 1,500.

Examples of the polyether polyol (a) include the following (a1) to (a3) and a mixture of two or more thereof.

(A1): Aliphatic dihydric alcohol alkylene oxide (hereinafter, “alkylene oxide” is abbreviated as “AO”) adduct 1,4-butanediol ethylene oxide (hereinafter, “ethylene oxide” is referred to as “EO”) 5 mol adduct, propylene oxide of 1,6-hexanediol (hereinafter “propylene oxide” is abbreviated as “PO”) 5 mol adduct, and 5 mol addition of neopentyl glycol butylene oxide Things

(A2): polyoxyalkylene glycol polyoxyethylene glycol (Mn400), polyoxypropylene glycol (Mn600), polyoxytetramethylene glycol (Mn1,000), etc.

(A3): AO adduct of dihydric phenol compound (AO 2 to 20 mol)
Divalent phenol compounds [monocyclic phenols (catechol, resorcinol, hydroquinone, etc.), condensed polycyclic phenols (dihydroxynaphthalene, etc.), bisphenol compounds (bisphenol A, bisphenol-F, bisphenol-S, etc.)] AO adduct [resorcinol EO4 mol adduct, PO4 mol adduct of dihydroxynaphthalene, EO2 mol adducts of bisphenol A, bisphenol-F and bisphenol-S, etc.]

  Of these polyether polyols (a), preferred are (a1) and (a2), more preferably (a2), from the viewpoint of low shrinkage.

Examples of the organic polyisocyanate (b) used as the raw material for the urethane prepolymer (d) include the following (b1) to (b4) and a mixture of two or more thereof.

(B1): Aromatic polyisocyanate 1,3- and / or 1,4-phenylene diisocyanate 2,4- and / or 2,6-tolylene diisocyanate (TDI), 4,4'- and / or 2,4 '-Diphenylmethane diisocyanate (MDI), m- and p-isocyanatophenylsulfonyl isocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-Dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, and m- and p-isocyanatophenylsulfonyl isocyanate

(B2): aliphatic polyisocyanate ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4- and / or Or 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, 2,6-diisocyanatoethylcaproate, bis (2-isocyanatoethyl) fumarate, bis (2 -Isocyanatoethyl) carbonate and trimethylhexamethylene diisocyanate (TMDI)

(B3): cycloaliphatic polyisocyanate isophorone diisocyanate (IPDI), 2,4- and / or 2,6-methylcyclohexane diisocyanate (hydrogenated TDI), dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), Cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1,2-dicarboxylate and 2,5- and / or 2,6-norbornane diisocyanate, dimer acid diisocyanate

(B4): aromatic aliphatic polyisocyanate m- and / or p-xylylene diisocyanate (XDI), diethylbenzene diisocyanate and α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI)

  Of these organic polyisocyanates (b), (b1) and (b3) are preferred from the viewpoint of low curing shrinkage, and (b3) is more preferred.

  The OH / NCO equivalent ratio in the reaction of the polyether polyol (a) and the organic polyisocyanate (b) is 0.45 to 0.99, preferably 0.50 to 0.97, more preferably 0.55 to 0.95. It is. If the amount ratio is less than 0.45, the shrinkage rate at the time of curing is increased and the adhesion to the substrate described later is deteriorated, and if it exceeds 0.99, the compatibility with (meth) acrylate is deteriorated.

  The urethane prepolymer (d) having an isocyanate group obtained by the above reactions (a) and (b) is further reacted with a hydroxyl group-containing (meth) acrylate (c) to form a bifunctional urethane as an essential component of the present invention. (Meth) acrylate (A) can be obtained.

  Examples of the hydroxyl group-containing (meth) acrylate (c) include the following (c1) to (c6) and a mixture of two or more thereof.

(C1): AO adduct of (meth) acrylic acid (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid-2-hydroxybutyl and their AO addition Things

(C2): ε-caprolactone adduct of (c1) (meth) acrylic acid-2-hydroxyethyl-ε-caprolactone 2 mol adduct, etc.

(C3): Mono (meth) acrylate diol diol [polycarbonate diol, polyether diol, polyester diol] mono (meth) acrylate

(C4): Reaction product of epoxide and hydroxy (meth) acrylic acid 3-phenoxy-2-hydroxypropyl (meth) acrylate, 3-biphenoxy-2-hydroxyprop (meth) acrylate, etc.

(C5): (Meth) acrylic acid and trifunctional or higher polyol reaction product and adduct thereof Glycerol mono (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, ditrimethylolpropane Mono (meth) acrylate, dipentaerythritol mono (meth) acrylate and their AO adducts, etc.

(C6): reaction product of (meth) acrylic acid and at least one polyol selected from the group consisting of butadiene polyol, isoprene polyol, hydrogenated butadiene polyol and hydrogenated isoprene polyol

  Of these hydroxyl group-containing (meth) acrylates (c), (c1) and (c2) are preferred from the viewpoint of reactivity with the polyisocyanate component (b), and (c1) is more preferred. is there.

  In the production of the bifunctional urethane (meth) acrylate (A) of the present invention, a urethanization catalyst may be used. Urethane catalysts include metal compounds (organic bismuth compounds, organic tin compounds, organic titanium compounds, etc.), tertiary amines, amidine compounds and quaternary ammonium salts.

  The use amount of the urethanization catalyst is usually 1% by weight or less based on the weight of (A), preferably 0.001 to 0.5% by weight, more preferably 0.05 to 0.5% from the viewpoint of reactivity and transparency. 0.2% by weight.

  The content of (A) in the present invention is usually 5 to 45% by weight, preferably 10 to 40% by weight, based on the total weight of (A), (B) and (C). If the content of (A) is less than 5%, the curing shrinkage is large, so that the adhesion is deteriorated. On the other hand, if it exceeds 45%, the viscosity becomes high and the handling property is deteriorated.

The polyfunctional (meth) acrylate (B) having 3 to 5 functional groups, which is the second essential component in the present invention, is a compound (B1) in which X in the following general formula is a hydroxyl group, a methyl group or a (meth) acryloyloxy group To (B3), and a mixture of two or more thereof.

[In Formula (1), X represents a hydroxyl group, a methyl group, or a (meth) acryloyloxy group. R represents a hydrogen atom or a methyl group; R ′ represents a hydrogen atom or a methyl group, and a, b and c each independently represent an integer of 0 to 30. ]

In formula (1), X represents a hydroxyl group, a methyl group or a (meth) acryloyloxy group.
Of these, a (meth) acryloyloxy group is preferable, and an acryloyloxy group is more preferable.

In formula (1), R is represented by a hydrogen atom or a methyl group, preferably a hydrogen atom.

In the formula (1), when R ′ is a hydrogen atom, it corresponds to addition of ethylene oxide, and when it is a methyl group, it corresponds to addition of propylene oxide.
Ethylene oxide single addition, propylene oxide single addition, block addition or random addition of ethylene oxide and propylene oxide may be used.

a, b and c each represents the number of moles of ethylene oxide and / or propylene oxide, each independently usually a number of 0 to 10, preferably 0 to 5, more preferably 0 to 2, particularly preferably all 0. It is. (A + b + c) is a number from 0 to 30, preferably 0 to 15, particularly preferably 0 to 5.

In the present invention, the polyfunctional (meth) acrylate (B) having 3 to 5 functional groups is a compound (B1) to (B3) in which X in the following general formula is a hydroxyl group, a methyl group or a (meth) acryloyloxy group. The following are specific examples. The following compounds may be used alone or a mixture thereof.

(B1): Compound in which X in general formula (1) is a hydroxyl group Pentaerythritol triacrylate, triacrylate of pentaerythritol EO 10 mol adduct, triacrylate of pentaerythritol PO5 mol adduct, etc.

(B2): a compound in which X in the general formula (1) is a methyl group trimethylolpropane triacrylate, trimethylolpropane EO 20 mol adduct triacrylate, trimethylolpropane PO5 mol adduct trimethacrylate, etc.

(B3): Compound in which X in formula (1) is acryloyloxy group Pentaerythritol tetraacrylate, triacrylate of 15 mol adduct of pentaerythritol, tetramethacrylate of PO5 mol adduct of pentaerythritol, etc.

  Of these polyfunctional (meth) acrylates (B), (B2) and (B3) are preferable from the viewpoint of scratch resistance, and (B3) is more preferable.

The content of (B) in the present invention is usually 25 to 50%, preferably 30 to 40%, based on the total weight of (A), (B) and (C). When the content of (A) is less than 25%, the scratch resistance is deteriorated. On the other hand, if it exceeds 50%, the curing shrinkage rate becomes worse, the warpage becomes larger, and the adhesion is lowered.

The aromatic ring-containing monofunctional (meth) acrylate (C), which is the third essential component in the present invention, has an aromatic ring in the molecule and contains at least one (meth) acryloyl group. Its chemical structure is not limited.

Examples of the aromatic ring-containing monofunctional (meth) acrylate (C) include the following (C1) to (C3) and mixtures of two or more thereof.

(C1): monofunctional (meth) acrylate having a phenyl group in the molecule benzyl (meth) acrylate, phenylethyl (meth) acrylate, (meth) acrylate of phenol EO 1 mol adduct, phenol EO 2 mol adduct ( (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, (meth) acrylate of EO 1 mol adduct of tribromophenol, (meth) acrylate of EO 1 mol adduct of nonylphenol, etc.

(C2): monofunctional (meth) acrylate having a biphenyl group in the molecule o-, m-, or mono (meth) acrylate of p-phenylphenol, 3,3′-diphenyl-4,4′-dihydroxybiphenyl Mono (meth) acrylate, mono (meth) acrylate of o-, m-, or p-phenylphenol AO adduct, mono (meth) acrylate of 3,3′-diphenyl-4,4′-dihydroxybiphenyl Acrylate etc.

(C3): monofunctional (meth) acrylate having a styrenated phenoxy group in the molecule 2.5 mol of styrene added to phenol, mono (meth) acrylate of styrenated phenol, 2.5 mol of styrene added to phenol Mono (meth) acrylate of AO adduct of styrenated phenol, mono (meth) acrylate of AO adduct of styrenated phenol with 3 moles of styrene added to phenol, etc.

  Of these aromatic ring-containing monofunctional (meth) acrylates (C), (C1) and (C3) are preferable from the viewpoint of resin adhesion after wet heat treatment, and (C1) is more preferable.

The content of (C) in the present invention is usually 20 to 60%, preferably 25 to 50%, based on the total weight of (A), (B) and (C). When the content of (A) is less than 20%, the resin adhesion after the wet heat treatment is deteriorated. On the other hand, if it exceeds 60%, the scratch resistance deteriorates.

As the photoinitiator (D) as the fourth essential component in the present invention, a hydroxybenzoyl compound (2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, benzoin alkyl) Ether, etc.), benzoylformate compound (methylbenzoylformate, etc.), thioxanthone compound (isopropylthioxanthone, etc.), benzophenone (benzophenone, etc.), phosphate compound (1,3,5-trimethylbenzoyldiphenylphosphine oxide, etc.), benzyl Examples thereof include dimethyl ketal.
Two or more of these may be used in combination.

  Of these photopolymerization initiators (D), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 1,3,3 are preferred from the viewpoint of preventing coloring of the cured product. 5-trimethylbenzoyldiphenylphosphine oxide.

The content of (D) in the present invention is preferably 0.3 to 10% by weight from the viewpoint of curability and coloring of the cured product based on the sum of (A), (B), (C) and (D). More preferably, it is 0.5 to 5% by weight.

Moreover, you may make the ultraviolet curable resin for optical components of this invention contain various additives (E) as needed in the range which does not inhibit the effect of this invention.
Additives include mold release agents (alkyl phosphate esters, salts of alkyl phosphate esters and dimethylalkylamine, etc.), plasticizers, organic solvents, inorganic fillers, dispersants, antifoaming agents, leveling agents, silanes A coupling agent, a thixotropic agent (thickening agent), a slip agent, an antioxidant, and an ultraviolet absorber are included.

  Although the manufacturing method of the molded object using the resin composition of this invention is not specifically limited, For example, it can apply and shape | mold by the following method. That is, a mold (mold temperature is usually 20 to 50 ° C., preferably 25 to 40 ° C.) in which the temperature of the resin composition of the present invention is previously adjusted to 20 to 50 ° C. to obtain a molded body shape (for example, optical lens shape). Using a dispenser, etc., apply (or fill) the cured film to a thickness of 50 to 150 μm, and press laminate the transparent base material (including the transparent film) over the coating so that air does not enter. Furthermore, after irradiating the ultraviolet rays described later from the transparent substrate to cure the coating film, the film is released from the mold to obtain a film-like cured product or a sheet-like cured product.

When the resin composition of the present invention is cured by ultraviolet rays, various ultraviolet irradiation devices [for example, ultraviolet irradiation devices [model number “VPS / I600”, manufactured by Fusion UV Systems Co., Ltd.] can be used. Examples of the lamp to be used include a high-pressure mercury lamp and a metal halide lamp. The irradiation amount of ultraviolet rays (mJ / cm ² ) is preferably 10 to 10,000, more preferably 100 to 5,000, from the viewpoints of curability of the composition and flexibility of the cured product.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

Production Example 1
In a reaction vessel equipped with a stirrer, a condenser and a thermometer, polytetramethylene glycol having a molecular weight of 1000 [trade name: PTMG-1000, manufactured by Mitsubishi Chemical Corporation] 597 parts, 265 parts of isophorone diisocyanate [trade name: VESTANAT IPDI, BASF Japan Co., Ltd.] and 0.5 parts of bismuth tri (2-ethylhexanoate) (2-ethylhexanoic acid 50% solution) as a catalyst were added and reacted at 80 ° C. for 4 hours, and then 2-hydroxyethyl acrylate 138 parts were added and reacted at 80 ° C. for 3 hours to obtain urethane acrylate (A-1) of the present invention.

Production Example 2
In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 361 parts of a PO2 molar adduct of bisphenol A having a molecular weight of 344 [trade name: Newpol BP-2P, manufactured by Sanyo Chemical Industries, Ltd.], xylylene diisocyanate [ Trade name: Takenate 500, manufactured by Mitsui Takeda Chemical Co., Ltd.] 395 parts and bismuth tri (2-ethylhexanoate) (2-ethylhexanoic acid 50% solution) 0.5 part as urethanization catalyst, 6 at 80 ° C. Then, 244 parts of 2-hydroxyethyl acrylate was added and reacted at 80 ° C. for 3 hours to obtain urethane acrylate (A-2) of the present invention.

Comparative production example 1
In a reaction vessel equipped with a stirrer, a condenser and a thermometer, 228 parts of polyethylene glycol (trade name: PEG200, manufactured by Sanyo Chemical Industries), 507 parts of isophorone diisocyanate and bismuth tri (2- Ethyl hexanoate) (2-ethylhexanoic acid 50% solution) 0.2 part was charged, reacted at 80 ° C. for 4 hours, then 265 parts of 2-hydroxyethyl acrylate was added, and reacted at 80 ° C. for 3 hours for Comparative Example Urethane acrylate (A'-1) for was obtained.

Comparative production example 2
In a reaction vessel equipped with a stirrer, a condenser and a thermometer, 868 parts of polypropylene glycol (trade name: Sannix PP-4000, manufactured by Sanyo Chemical Industries, Ltd.) with a molecular weight of 4,000, xylylene diisocyanate [trade name: Takenate 500, manufactured by Mitsui Takeda Chemical Co., Ltd.] 82 parts and bismuth tri (2-ethylhexanoate) (2-ethylhexanoic acid 50% solution) 0.2 part as urethanization catalyst were charged and reacted at 80 ° C. for 5 hours. Then, 50 parts of 2-hydroxyethyl acrylate was added and reacted at 80 ° C. for 3 hours to obtain urethane acrylate (A′-2) for a comparative example.

Example 1
15 parts by weight of the urethane acrylate (A-1) synthesized in Production Example 1, 10 parts by weight of the urethane acrylate (A-2) synthesized in Production Example 2, pentaerythritol triacrylate [trade name “Light Acrylate PE-3A”, Kyoeisha Chemical Co., Ltd.] (B-1) 30 parts by weight, phenoxyethyl acrylate [trade name “Light Acrylate PO-A”, Kyoeisha Chemical Co., Ltd.] (C-1) 35 parts by weight, 1-hydroxycyclohexylphenyl Ketone [trade name “Irgacure 184”, manufactured by Ciba Specialty Chemicals Co., Ltd.] (D-1) 2 parts by weight, 2-ethylhexyl acid phosphate [trade name “AP-8”, manufactured by Daihachi Chemical Co., Ltd.] (E -1) was mixed at once, and was uniformly mixed and stirred with a disperser to obtain an ultraviolet curable resin composition of the present invention.

Examples 2-6 and Comparative Examples 1-6
Resin compositions for optical components of Examples 2 to 6 and Comparative Examples 1 to 6 were obtained in the same manner as in Example 1 according to the components and blending amounts shown in Table 1.

  In addition, the symbol of the compound described in Table 1 represents the following compounds.

(B-2): Pentaerythritol tetraacrylate [trade name “Light acrylate PE-4A”, manufactured by Kyoeisha Chemical Co., Ltd.]
(B-3): Triacrylate of trimethylolpropane with 20 mol of ethylene oxide adduct [trade name “SR-415”, manufactured by Sartomer Japan, Inc.]
(B′-1): Dipentaerythritol hexaacrylate [trade name “Light Acrylate DPE-6A”, manufactured by Kyoeisha Chemical Co., Ltd.]
(C-2): Monoacrylate of EO 1 mol adduct of o-phenylphenol [trade name “A-LEN-10” manufactured by Shin-Nakamura Chemical Co., Ltd.]
(D-2): 1,3,5-trimethylbenzoyldiphenylphosphine oxide [trade name “Darocur TPO”, manufactured by Ciba Specialty Chemicals Co., Ltd.]
(E-2): Dimethylstearylamine [trade name “Farmin DM8098”, manufactured by Kao Corporation]
(E-3): Hindered phenol antioxidant [trade name “Irganox 1010”, manufactured by Ciba Specialty Chemicals Co., Ltd.]

The scratch resistance, warpage, adhesion after wet heat treatment, and total light transmittance of the resin composition for comparison with the present invention were measured by the following methods.
The performance results are shown in Table 1.

<How to make a film for performance evaluation>
After coating the resin composition on one side of a glass plate with an applicator so as to have a thickness of 20 μm, a 100 μm-thick PET film [trade name “Cosmo Shine A4300” manufactured by Toyobo Co., Ltd.] is applied to the resin side. Bonding was performed, and the roller was rolled from above to extrude air.
From the PET film side, ultraviolet rays were irradiated at 1000 mJ / cm ² by an ultraviolet irradiation device [model number “VPS / I600”, manufactured by Fusion UV Systems Co., Ltd.] and cured. The cured product adhered to the PET film was peeled off from the glass plate, and a film for performance evaluation was created.

<Performance evaluation method>
(1) Scratch resistance A double-sided tape of the same size is affixed to a 2 cm x 2 cm acrylic plate, and the same size of unused steel wool # 0000 [trade name "Bonster", Nippon Steel Wool Co., Ltd. )]. A double-sided tape of the same size is attached to the side of the acrylic plate that does not have steel wool, and the adhesive surface is attached to a 500 g weight.
A film for performance evaluation is cut into a 10 cm × 10 cm square, placed on a horizontal base with the coated surface facing up, and a weight with steel wool affixed on it.
Hold the body of the weight by hand, reciprocate the weight 10 times horizontally against the coating film, conduct a friction test, and visually determine the appearance according to the following criteria.

○: No scratches are attached.
Δ: Nine or fewer scratches are observed.
X: 10 or more scratches are observed, and the surface is whitened.

(2) The film for warpage performance evaluation was cut into a 6 cm × 6 cm square, placed on a flat table, the warpage (mm) from the four end tables of the square was measured, and the average value of 4 points was calculated.

(3) A film for evaluation of resin adhesion performance after wet heat treatment was cut into a 10 cm × 10 cm square and 50 in a constant temperature and humidity chamber (SH-641, manufactured by Espec Corp.) at 60 ° C. and a relative humidity of 95%. Let stand for hours.
Then, it is left to stand for 24 hours in a room adjusted to 23 ° C. and 50% relative humidity, and the test piece is cut into a 1 mm width with a cutter knife in accordance with JIS K 5600-5-6. 10 × 10). A cellophane adhesive tape was applied on the grid and peeled by 90 degrees, and the peeled state of the cured product from the PET film was visually observed and evaluated according to the following criteria.

○: 90% or more area of the cured product remains on the base material Δ: Area of the cured product 10 to 90% remains on the base material ×: Area of the cured product remaining on the base material is less than 10%

(4) Transparency (total light transmittance)
Based on JIS-K7105, the film for performance evaluation was measured for total light transmittance (%) using a total light transmittance measuring device [trade name “haze-garddual” manufactured by BYK Gardner Co., Ltd.].

From the results of Table 1, the films obtained by curing the ultraviolet curable resin compositions of the present invention of Examples 1 to 6 have small warpage while maintaining scratch resistance, and resin adhesion after wet heat treatment. It can be seen that the transparency is excellent.
On the other hand, Comparative Example 1 containing no urethane acrylate (A), Comparative Example 2 using a hexafunctional acrylate, and Comparative Example using a urethane acrylate (A′-1) containing a low molecular polyol having a molecular weight of 200 as a constituent component No. 5 had a large warp, and Comparative Example 2 and Comparative Example 5 also deteriorated the resin adhesion after wet heat treatment.
In Comparative Example 4 not containing the aromatic ring-containing monofunctional acrylate (C), the resin adhesion after the wet heat treatment was deteriorated.
In Comparative Example 3 in which the polyfunctional acrylate (B) is not used, and in Comparative Example 6 in which the urethane acrylate (A′-2) containing a high molecular weight polyol having a molecular weight of 4,000 as a constituent component is used, the scratch resistance is poor.

Since the ultraviolet curable resin for optical components of the present invention is excellent in scratch resistance, low warpage, resin adhesion after wet heat treatment, and transparency, it is also useful as an optical member and electrical / electronic member.
The optical parts using the cured product of the present invention are used in the form of a film or sheet, as well as plastic lenses (prism lenses, lenticular lenses, microlenses, Fresnel lenses, viewing angle improvement lenses, etc.), electromagnetic shielding films. It is useful as prisms, optical fibers, solder resists for flexible printed wiring, plating resists, interlayer insulating films for multilayer printed wiring boards, and photosensitive optical waveguides.

Claims (6)

A bifunctional urethane obtained by reacting a polyether polyol (a) having an oxyalkylene chain in the molecule and a number average molecular weight of 300 to 2,000, an organic polyisocyanate (b) and a hydroxyl group-containing (meth) acrylate (c). (Meth) acrylate (A), polyfunctional (meth) acrylate (B) having 3 to 5 functional groups, monofunctional (meth) acrylate (C) containing an aromatic ring in the molecule, and photopolymerization initiator (D) An ultraviolet curable resin composition comprising: The ultraviolet curable resin composition according to claim 1, wherein the polyfunctional (meth) acrylate (B) is represented by the following general formula (1).

[In Formula (1), X represents a hydroxyl group, a methyl group, or a (meth) acryloyloxy group. R represents a hydrogen atom or a methyl group; R ′ represents a hydrogen atom or a methyl group, and a, b and c each independently represents an integer of 0 to 10. ] The ultraviolet curable resin composition of Claim 1 or 2 which contains 25-50 weight% of this polyfunctional (meth) acrylate (B) based on the total weight of (A), (B), and (C). . The ultraviolet curable type according to any one of claims 1 to 3, comprising 5 to 45% by weight of the bifunctional urethane (meth) acrylate (A) based on the total weight of (A), (B), and (C). Resin composition.   Hardened | cured material for optical members formed by hardening the ultraviolet curable resin composition in any one of Claims 1-4 by ultraviolet irradiation.   An optical film or optical sheet obtained by curing the ultraviolet curable resin composition according to claim 1 by ultraviolet irradiation.