JP2006241234A - Optical recording medium and coating agent therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating agent for an optical recording medium, comprising an active energy radiation-curing resin composition which shows a low viscosity and a good workability at application and is excellent in transparency, adhesiveness and environment resistance such as moisture resistance and heat resistance. <P>SOLUTION: The coating agent for the optical recording medium comprises the active energy radiation-curing resin composition comprising a urethane (meth)acrylate compound [I] obtained by reacting a polyol component (A), a polyisocyanate component (B) and a hydroxy group-containing (meth)acrylate component (C), an ethylenically unsaturated compound [II] and a silica particle [III]. Here, the polyol component (A) contains a carboxy group-containing polyol (a3) and a polyoxypropylene glycol (a1) with a number average molecular weight of 300-2,000 and/or an aliphatic copolycarbonate diol (a2) with a number average molecular weight of 300-2,000 having a specific repeating unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coating agent for an optical recording medium comprising an active energy ray-curable resin composition. More specifically, the present invention relates to a coating composition having a low viscosity and good coatability, and transparency, surface hardness, adhesion, and shrinkage resistance against curing. The present invention relates to a coating agent for an optical recording medium comprising an active energy ray-curable resin composition excellent in environmental resistance such as heat resistance, moisture resistance and heat resistance. The present invention also relates to an optical recording medium having such a cured layer of the coating agent for optical recording medium.

  2. Description of the Related Art Conventionally, active energy ray-curable resin compositions have been widely used for coating agents and adhesives for various substrates. It is also widely used in optical applications. Specific examples thereof include a protective film for an information recording layer in an optical recording medium. In recent years, application to a next-generation high-density optical disk using a blue laser has been studied. Yes.

  Specifically, the next-generation high-density optical disk is formed by forming a recording film on a transparent or opaque support substrate made of plastic or the like, and then laminating a transparent layer of about 100 μm on the recording film. The optical disc is used so that recording light and / or reproduction light is incident from the transparent layer side through the transparent layer.

  These optical discs are not yet sufficiently reduced in the shrinkage ratio of the curable composition, so that warping occurs and recording and / or reproduction cannot be performed; However, there is a problem that recording and / or reproduction cannot be sufficiently performed using the light beam, and the present situation is not sufficient for practical use.

  Therefore, as a countermeasure for the above problem, a protective layer having a low curing shrinkage rate using, for example, urethane (meth) acrylate has been proposed (for example, see Patent Document 1).

Moreover, the proposal of the organic-inorganic hybrid composition of the inorganic component containing the silica particle which consists of a hydrolyzate of an alkoxysilane oligomer, an ethylenically unsaturated compound, and / or its oligomer is also made | formed (for example, refer patent document 2).
JP 2002-245672 A JP 2004-169028 A

  However, in the technique disclosed in Patent Document 1, since the protective layer is made thicker than the conventional one, the protective layer alone is insufficient in hardness, and further, the colloidal silica fine particles and the ethylenically unsaturated compound are cured. Although the strength and cure shrinkage are balanced by laminating an object as a hard coat layer, such a laminate type protective film is still poor in practicality in terms of cost and operability Met.

  In addition, the disclosed technique of Patent Document 2 has sufficient strength and low curing shrinkage even when the film is thickened, but satisfies all of adhesion to the base material, environmental resistance, and high surface hardness, and In terms of the difficulty in reducing the viscosity required to ensure sufficient coating workability, the method is still not satisfactory, and further improvements are desired.

  Thus, the conventionally known active energy ray-curable resin composition having transparency as used for a protective film of an optical recording medium has a problem in strength and cure shrinkage when the film is thickened. Alternatively, there is a problem that it is difficult to ensure application workability after satisfying adhesion to the substrate, environmental resistance, and high surface hardness.

  For this reason, it has the transparency, environmental resistance, high adhesion, and coating workability that conventional protective films have, and has sufficient strength and low curing shrinkage even when thickened. The advent of a functional resin composition has been desired.

  Accordingly, the present invention has an active energy ray having a low viscosity and good application workability and excellent environmental resistance such as transparency, high surface hardness, adhesion, curing shrinkage resistance, moisture resistance and heat resistance. An object of the present invention is to provide an optical recording medium comprising a coating agent for an optical recording medium comprising a curable resin composition and a cured product layer of such a coating agent for an optical recording medium.

As a result of intensive studies in view of such circumstances, the present inventors have obtained a polyol component containing a specific polyoxypropylene glycol (a1) and / or an aliphatic copolycarbonate diol (a2) and a carboxyl group-containing polyol (a3). (A), urethane (meth) acrylate compound [I] obtained by reacting polyisocyanate component (B) and hydroxyl group-containing (meth) acrylate component (C), ethylenically unsaturated compound [II], and silica particles The inventors have found that an active energy ray-curable resin composition containing [III] meets the above object as a coating agent for optical recording media, and has completed the present invention.
That is, the gist of the present invention is as follows.

（式中Ｒ¹とＲ²、及びＲ³とＲ⁴は同じでも異なってもよく、Ｈ又はＣＨ_３であり、１≦ｎ≦４，１≦ｍ≦４である。） [1] A polyoxypropylene glycol (a1) having a number average molecular weight of 300 to 2000 and / or a repeating unit of the following (i) and (ii), and a ratio (molar ratio) between (i) and (ii): Is a polyol component (A) comprising an aliphatic copolycarbonate diol (a2) having a number average molecular weight of 300 to 2000 and a carboxyl group-containing polyol (a3), and a polyisocyanate component (B). And an urethane (meth) acrylate compound [I] obtained by reacting a hydroxyl group-containing (meth) acrylate component (C), an ethylenically unsaturated compound [II], and silica particles [III]. A coating agent for optical recording media, comprising an energy beam curable resin composition.

(In the formula, R ¹ and R ² , and R ³ and R ⁴ may be the same or different, and are H or CH ₃ , and 1 ≦ n ≦ 4, 1 ≦ m ≦ 4.)

[2] The urethane (meth) acrylate compound [I] contains a polyol component (a4) other than the above (a1) to (a3) as the polyol component (A) [1] The coating agent for optical recording media as described.

[3] The coating agent for optical recording media according to [2], wherein the polyol component (a4) is a low molecular weight polyol having a number average molecular weight of 300 or less.

[4] The coating for optical recording media according to [1] to [3], wherein the polyisocyanate component (B) is at least one selected from isophorone diisocyanate and hydrogenated xylene diisocyanate. Agent.

[5] The coating agent for optical recording media according to [1] to [4], wherein the acid value of the urethane (meth) acrylate compound [I] is 1.5 to 50 KOH-mg / g.

[6] The ethylenically unsaturated compound [II] contains an alicyclic (meth) acrylate monomer having a glass transition point (Tg) of 0 ° C. or higher. Coating agent for optical recording media.

[7] To contain 10 to 150 parts by weight of ethylenically unsaturated compound [II] and 5 to 100 parts by weight of silica particles [III] with respect to 100 parts by weight of urethane (meth) acrylate compound [I]. The coating agent for optical recording media according to [1] to [6], which is characterized in that

[8] The active energy ray-curable resin composition contains a urethane (meth) acrylate compound [IV] other than the urethane (meth) acrylate compound [I] [1] to [7] The coating agent for optical recording media described in 1.

[9] The urethane (meth) acrylate compound [IV] includes a urethane (meth) acrylate compound obtained by reacting the polyisocyanate component (B) and the hydroxyl group-containing (meth) acrylate component (C). The coating agent for optical recording media according to [8].

[10] The coating agent for optical recording media according to [1] to [9], wherein the silica particles [III] contain a hydrolyzate of an alkoxysilane oligomer.

[11] The coating agent for optical recording media according to [1] to [10], wherein the active energy ray-curable resin composition contains a photopolymerization initiator [V].

[12] An optical recording medium having a cured product layer made of the coating agent for optical recording media according to [1] to [11].

  According to the present invention, while having transparency as a conventional coating agent for optical recording media, the viscosity is low even in the absence of a solvent, the coating workability is good, the surface hardness is high, moisture resistance, heat resistance, etc. An optical recording medium having a coating material for an optical recording medium having excellent environmental resistance, low cure shrinkage, and excellent adhesion to a substrate, and a cured product layer formed by such a coating agent for an optical recording medium A medium is provided.

  The embodiments of the coating agent for optical recording media and the optical recording medium of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of the embodiment of the present invention. The present invention is not specified in these contents unless it exceeds the gist.

  In the present invention, “(meth) acrylic acid” means “acrylic acid or methacrylic acid”, and “(meth) acrylate” means “acrylate or methacrylate”.

[Component composition of active energy ray-curable resin composition]
The active energy ray-curable resin composition constituting the coating agent for an optical recording medium of the present invention is a polyoxypropylene glycol (a1) having a number average molecular weight of 300 to 2000 and / or the following (i) and (ii): An aliphatic copolycarbonate diol (a2) having a ratio (molar ratio) of (i) and (ii) of 9: 1 to 1: 9 and a number average molecular weight of 300 to 2000, and a carboxyl group-containing A urethane (meth) acrylate compound [I] obtained by reacting a polyol component (A) containing a polyol (a3), a polyisocyanate component (B) and a hydroxyl group-containing (meth) acrylate component (C); In the present invention, this specific urethane (meth) acrylate compound is composed of a saturated compound [II] and silica particles [III]. By using [I] as a component of the composition of the present invention, the composition according to the present invention exhibits particularly low viscosity characteristics and low curing shrinkage, and the composition according to the present invention has transparency, adhesion, high surface hardness, moisture resistance. Environment resistance such as heat resistance and heat resistance can be imparted.

（式中Ｒ¹とＲ²、及びＲ³とＲ⁴は同じでも異なってもよく、Ｈ又はＣＨ_３であり、１≦ｎ≦４，１≦ｍ≦４である。）

(In the formula, R ¹ and R ² , and R ³ and R ⁴ may be the same or different, and are H or CH ₃ , and 1 ≦ n ≦ 4, 1 ≦ m ≦ 4.)

<Urethane (meth) acrylate compound [I]: Component [I]>
(Polyol component (A))
Polyoxypropylene glycol (a1) having a number average molecular weight of 300 to 2000 used to obtain component [I]: Component (a1) is a polypropylene oxide homopolymer, for example, a product from Asahi Denka Kogyo Co., Ltd. Names “Adeka Polyether P-400”, “Adeka Polyether P-700”, “Adeka Polyether P-1000”, “Adeka Polyether P-2000”, product name “Uniol D-400” from Nippon Oil & Fats Co., Ltd. , “Uniol D-700”, “Uniol D-1000”, “Uniol D-2000”, trade names “Actol Diol-400”, “Actol Diol-700”, “Actol” from Mitsui Takeda Chemical Co., Ltd. "Cole Diol-1000", "Act Call Diol-1500", "Act Call Diol-20" 0 ", trade name from Sanyo Chemical Industries Co., Ltd." San Knicks PP-400 "," San Knicks PP-1000 ", it is possible to use those which are commercially available as such as" San Knicks PP-2000 ". By using component (a1) as component [I], a cured product having particularly low environmental resistance while having low viscosity characteristics and low curing shrinkage can be obtained.

  The number average molecular weight of the component (a1) used in the present invention is 300 to 2000, and when the number average molecular weight is less than 300, the viscosity tends to be high and the coating property tends to be poor. When the number average molecular weight exceeds 2000, Although the viscosity is lowered, it is not preferable because the surface hardness of the cured product is lowered. The lower limit of the particularly preferable number average molecular weight range is 700, more preferably 800, and the upper limit is 1500, and more preferably 1200.

  Aliphatic copolycarbonate diol component (a2) used to obtain component [I]: Component (a2) is a variety of methods described by Schell, Polymer Review Vol. 9, pages 9-20 (1964). And is composed of the repeating units (i) and (ii) above.

  Examples of the diol having an aliphatic alkylene group that satisfies the unit (i) used for obtaining the component (a2) include ethylene glycol, 1,2-propanediol, 1,4-butanediol, and 2,3-butane. Examples include diol, 1,6-hexanediol, 2,5-hexanediol, 1,8-octanediol, and the like. These may be used alone or in combination of two or more.

  Examples of the diol having an aliphatic alkylene group satisfying the unit (ii) include 1,3-propanediol, 1,3-butanediol, neopentyl glycol, 1,5-pentanediol, and 1,7-heptane. Examples include diol, 3-methyl-1,5-pentanediol, and 1,9-nonanediol. These may be used alone or in combination of two or more.

  By combining the units (i) and (ii), the component (a2) can suppress the crystallinity and exhibits effective flexibility. Furthermore, the units (i) and (ii) are preferably aliphatic diols having 5 to 8 carbon atoms from the viewpoint of hydrolysis resistance and weather resistance. For example, the aliphatic alkylene satisfying the unit (i) As the diol having a group, 1,6-hexanediol and 1,8-octanediol are preferable, and as the diol having an aliphatic alkylene group satisfying the unit (ii), 1,5-pentanediol, 1 , 7-pentanediol is preferably used.

  Particularly preferred aliphatic copolycarbonate diol component (a2) is 1,6-hexanediol in a diol having an aliphatic alkylene group satisfying the unit (i) and an aliphatic alkylene group satisfying the unit (ii). A copolymerized polycarbonate diol synthesized using 1,5-pentanediol as the diol is preferable because it is a viscous liquid at room temperature, is easy to handle, and is excellent in low-temperature characteristics and rebound resilience of the resulting composition. The ratio (molar ratio) of the above (i) and (ii), which are repeating units in the polymer, is 1: 9 to 9: 1, preferably 2: 8 to 8: 2, and more preferably 3: 7. ~ 7: 3. When the number of repeating units is out of the range of 1: 9 to 9: 1, flexibility is deteriorated, which is not preferable.

  The number average molecular weight of the component (a2) used in the present invention is 300 to 2000, and when the number average molecular weight is less than 300, the curing shrinkage tends to increase. It is difficult and not preferred. In particular, the lower limit of the range of the number average molecular weight is 500, more preferably 600, and the upper limit is 1500, more preferably 1200.

  By using component (a2) as component [I], a cured product having particularly low surface hardness can be obtained while having low viscosity characteristics and low cure shrinkage.

  Moreover, when the component (a1) and the component (a2) are used in combination as the component [I], a cured product having a balance between environmental resistance and surface hardness is obtained while having low viscosity characteristics and low curing shrinkage. Can do. The fine adjustment of the balance can be performed by adjusting the ratio of the component (a1) and the component (a2).

  Carboxyl group-containing polyol (a3): Component (a3) is a compound having one or more carboxyl groups and two or more hydroxyl groups. Specific examples thereof include 2,2-bis (hydroxymethyl) butyric acid, tartaric acid, 2,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2 , 2-bis (hydroxyethyl) propionic acid, 2,2-bis (hydroxypropyl) propionic acid, dihydroxymethylacetic acid, bis (4-hydroxyphenyl) acetic acid, 4,4-bis (4-hydroxyphenyl) pentanoic acid, A homogentisic acid etc. are mentioned. These may be used alone or in combination of two or more.

  Among these, 2,2-bis (hydroxymethyl) butyric acid and 2,2-bis (hydroxymethyl) propionic acid are preferable as the component (a3) from the viewpoint of the hardness and adhesion of the obtained cured product.

  In the present invention, as the polyol component (A), in addition to the components (a1), (a2), and (a3), other polyols (a4): component (a4) may be used in combination as necessary. Examples of a4) include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, 1,4-butanediol, polybutylene glycol, and 1,6-hexanediol. , Neopentyl glycol, cyclohexanedimethanol, hydrogenated bisphenol A, polycaprolactone, trimethylolethane, trimethylolpropane, polytrimethylolpropane, pentaerythritol, polypentaerythritol, sorbi And at least one structure of polyhydric alcohols such as polyol, mannitol, arabitol, xylitol, galactitol, glycerin, polyglycerin, polytetramethylene glycol, polyethylene oxide, ethylene oxide / propylene oxide block or random copolymerization Polyether polyol, polyester polyol or caprolactone which is a condensate of polyhydric alcohol such as polyhydric alcohol or polyether polyol and maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, adipic acid, isophthalic acid, etc. Examples thereof include caprolactone-modified polyol such as modified polytetramethylene polyol, polybutadiene-based polyol such as polyolefin-based polyol and hydrogenated polybutadiene polyol. These may be used alone or in combination of two or more.

  Among these, from the viewpoint of the hardness of the resulting cured product, the component (a4) is preferably a low molecular weight polyol having a molecular weight of 300 or less, for example, a molecular weight of 80 to 200, more preferably cyclohexanedimethanol or neopentyl glycol from the viewpoint of water resistance. Is mentioned.

(Polyisocyanate component (B))
Polyisocyanate component (B) used for obtaining component [I]: Component (B) is not particularly limited, and examples thereof include aromatics, aliphatics, cycloaliphatics, and alicyclics. Polyisocyanates, among which tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, modified diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, Isophorone diisocyanate, norbornene diisocyanate, allophanate-modified diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, phenylene diisocyanate Over DOO, lysine diisocyanate, lysine triisocyanate, trimer, etc. diisocyanate or of naphthalene diisocyanate is used. These may be used alone or in combination of two or more.

  Among these, the number average molecular weight of the polyisocyanate component (B) is preferably 150 to 700 from the viewpoint of reactivity with a hydroxyl group. In addition, isophorone diisocyanate and hydrogenated xylene diisocyanate are particularly preferably used from the viewpoints of transparency and weather resistance of the resulting cured product.

  Moreover, it is preferable from a corrosion-resistant viewpoint that the amount of hydrolyzable chlorine in a polyisocyanate component (B) is 100 ppm or less. The hydrolyzable chlorine amount in the present invention is a general term for substances contained in isocyanate and producing chlorine by hydrolysis, and the amount is defined as “hydrolyzable” defined in JIS K1556 (tolylene diisocyanate test method). It is calculated | required by the "chlorine" measuring method, and is the value converted into the amount of chlorine.

((Meth) acrylate component (C))
Hydroxyl-containing (meth) acrylate component (C) used to obtain component [I]: Component (C) is not particularly limited, and examples thereof include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) ) Acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxyethylacryloyl phosphate, 4-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, glycerin di (meth) acrylate 2-hydroxy-3-acryloyloxypropyl methacrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, ethylene Side-modified dipentaerythritol penta (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, isocyanuric acid ethylene oxide modified di (meth) acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate. These may be used alone or in combination of two or more.

  Among these, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate are preferably used as the hydroxyl group-containing (meth) acrylate component (C).

(Synthesis method)
As a synthesis method of the urethane (meth) acrylate compound [I],
(1) A method in which a polyol component (A) and a polyisocyanate component (B) are reacted and then a hydroxyl group-containing (meth) acrylate component (C) is reacted. (2) A polyisocyanate component (A) and a hydroxyl group-containing (meth) acrylate. Method of reacting component (C) and then reacting polyol component (A) (3) Reacting by charging batch of polyol component (A), polyisocyanate component (B) and hydroxyl group-containing (meth) acrylate component (C) The method of letting it be mentioned.

  Any of these methods may be used, but preferably (1) a method in which the polyol component (A) and the polyisocyanate component (B) are reacted and then the hydroxyl group-containing (meth) acrylate component (C) is reacted. Good.

  In this reaction, for the purpose of promoting the reaction, a metal catalyst such as dibutyltin dilaurate, an amine catalyst such as 1,8-diazabicyclo [5.4.0] undecene-7, bismuth ethylhexanoate, It is also preferable to use organic bismuth compounds such as bismuth naphthenate and bismuth neodecanoate as appropriate, and the reaction temperature is preferably 30 to 90 ° C., particularly 40 to 80 ° C.

(Physical properties)
The acid value of the urethane (meth) acrylate compound [I] used in the present invention is not particularly limited, but is preferably 1.5 to 50 KOH-mg / g, particularly 3 to 3, from the viewpoint of adhesion. It is preferable that it is 30KOH-mg / g. When the acid value is less than 1.5 KOH-mg / g, the adhesion to the base material is inferior. When the acid value exceeds 50 KOH-mg / g, the base material is inferior in environmental resistance such as corrosiveness and moisture resistance. It is not preferable.

  Moreover, as a weight average molecular weight of urethane (meth) acrylate type compound [I], it is preferable that it is 500-50,000, and also it is preferable that it is 1,000-30,000. When the weight average molecular weight is less than 500, the curing shrinkage ratio is increased, and when it exceeds 50,000, the viscosity becomes high, the coating property is deteriorated, and the hardness is remarkably inferior.

The weight average molecular weight of the urethane (meth) acrylate compound [I] is a weight average molecular weight in terms of standard polystyrene molecular weight, and is a high performance liquid chromatography (“Waters 2695 (main body)” manufactured by Waters, Japan). “Waters 2414 (detector)”), column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / line, packing material It is measured by using three series of materials: styrene-divinylbenzene copolymer, filler particle size: 10 μm.

<Urethane (meth) acrylate compound [IV]: Component (IV)>
Urethane (meth) acrylate compound [I] is an essential component for imparting environmental resistance such as transparency, adhesion, moisture resistance and heat resistance, but the hardness and acid value of the resulting composition are desired. Use of a urethane (meth) acrylate compound [IV] other than component [I] in combination for the purpose of adjusting the range is also suitably employed.

  The urethane (meth) acrylate compound [IV] is not particularly limited as long as it is other than the urethane (meth) acrylate compound [I]. Among them, the hardness and coatability of the resulting cured product are not limited. From the viewpoint, as the component [IV], those obtained by reacting the polyisocyanate component (B) and the hydroxyl group-containing (meth) acrylate component (C) are preferably used.

  The preferable blending ratio of the urethane (meth) acrylate compound [IV] in the active energy ray-curable resin composition according to the present invention is 80 weights with respect to 100 parts by weight of the urethane (meth) acrylate compound [I]. The amount is preferably not more than 50 parts by weight, particularly preferably not more than 50 parts by weight. When the urethane (meth) acrylate compound [IV] exceeds 80 parts by weight, the urethane (meth) acrylate compound [I] is sufficiently effective in improving environmental resistance such as transparency, adhesion, moisture resistance and heat resistance. It is not preferable because it cannot be expressed in

<Ethylenically unsaturated compound [II]: Component [II]>
The active energy ray-curable resin composition according to the present invention includes ethylene in combination with the urethane (meth) acrylate compound [I], from the viewpoints of low water absorption, environmental resistance, and lowering the viscosity of the composition. Unsaturated compound [II] is contained as an essential component.

  The ethylenically unsaturated compound [II] is not particularly limited, and conventionally known compounds can be used. For example, (meth) acrylic acid is bonded to a compound containing a hydroxyl group by an esterification reaction. Compounds and the like.

  Among such compounds, examples of monofunctional compounds include methyl (meth) acrylate, ethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxy. Butyl (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, dis Lopentenyl (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, phenol ethylene oxide modified (n = 2) (meth) acrylate, nonylphenol propylene oxide modified (n = 2.5) phthalic acid derivatives such as (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxy-2-hydroxypropyl phthalate Examples include fur (meth) acrylate, furfuryl (meth) acrylate, carbitol (meth) acrylate, benzyl (meth) acrylate, butoxyethyl (meth) acrylate, allyl (meth) acrylate, 2-acryloyloxyethyl acid phosphate monoester, and the like. It is done.

  Examples of the bifunctional compound include ethylene glycol di (meth) acrylate, diethylene 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, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaeryth Tall di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, diglycidyl phthalate di (meth) acrylate, hydroxypivalic acid modified neopentyl glycol di (meth) acrylate , Tricyclodecane dimethanol di (meth) acrylate, isocyanuric acid ethylene oxide modified diacrylate, 2-acryloyloxyethyl acid phosphate diester, and the like.

  Further, as the trifunctional or higher functional compound, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (Meth) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly (meth) acrylate, isocyanuric acid ethylene oxide modified triacrylate, ethylene oxide modified dipentaerythritol penta (meth) acrylate, ethylene oxide modified di Pentaerythritol hexa (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate , Ethylene oxide modified pentaerythritol tetra (meth) acrylate.

  In addition, styrene, vinyl toluene, chlorostyrene, α-methyl styrene, vinyl acetate, acrylonitrile, acryloyl morpholine, 2-hydroxyethyl acrylamide, N-methylol (meth) acrylamide, N-vinyl pyrrolidone, 2-vinyl pyridine, acrylic Examples thereof include a Michael adduct of acid and 2-acryloyloxyethyl dicarboxylic acid monoester. Examples of the Michael adduct of acrylic acid include acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, and methacrylic acid tetramer. 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, 2-methacryloyloxyethyl hexahydrophthalic acid monoester, and the like. Furthermore, other oligoester acrylates and epoxy acrylates are also included. These can be used alone or in combination of two or more.

  Among these, from the viewpoints of curability and low shrinkage, heat resistance, adhesion, and low water absorption of the resulting cured product, it contains an alicyclic (meth) acrylate monomer having a glass transition point (Tg) of 0 ° C. or higher. Is effective. Specific examples of the alicyclic (meth) acrylate monomer having a Tg of 0 ° C. or more include cyclohexyl (meth) acrylate [Tg = 15 ° C.], isobornyl (meth) acrylate [Tg = 97 ° C.], dicyclopentanyl (meth) ) Acrylate [Tg = 132 ° C.].

  Furthermore, a (meth) acrylate compound containing a hydroxyl group is preferably added for the purpose of improving adhesiveness and adhesion. Specific examples of the compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like.

  The preferable compounding ratio of the ethylenically unsaturated compound [II] in the active energy ray-curable resin composition according to the present invention is 10 to 150 parts by weight with respect to 100 parts by weight of the urethane (meth) acrylate compound [I]. In particular, it is preferably 15 to 100 parts by weight. When the blending ratio of the ethylenically unsaturated compound [II] is less than 10 parts by weight, the coating property is deteriorated because the viscosity is high. It is difficult to sufficiently exhibit environmental resistance effects such as heat resistance and heat resistance.

<Silica particles [III]: component [III]>
The active energy ray-curable resin composition according to the present invention contains silica particles [III] in addition to the urethane (meth) acrylate compound [I] and the ethylenically unsaturated compound [II].

  The silica particle [III] is not particularly limited, and silica particles composed of a hydrolyzate of so-called colloidal silica or an alkoxysilane oligomer can be used, and more preferably, an alkoxysilane oligomer hydrolyzed. Silica particles made of a product are used.

  The silica particles [III] are preferably ultrafine particles, and the upper limit of the number average particle diameter is preferably 50 nm or less, more preferably 40 nm or less, still more preferably 30 nm or less, particularly preferably 15 nm or less, and most preferably 12 nm or less. It is. On the other hand, the lower limit of the number average particle diameter is preferably 0.5 nm or more, more preferably 1 nm or more. When the number average particle size is too small, the cohesiveness of the ultrafine particles is extremely increased, and the transparency and mechanical strength of the cured product tend to be extremely decreased.

  Further, among the silica particles [III], the content of silica particles having a particle size of more than 30 nm and further silica particles having a particle size of more than 15 nm is preferably 1% by weight or less based on the active energy ray-curable resin composition. Further, it is preferably 0.5% by weight or less, and preferably 1% by volume or less, more preferably 0.5% by volume or less based on the cured product. When a large amount of silica particles having such a large particle size is contained in the composition, light scattering increases, which is not preferable because the transmittance decreases.

  For the determination of the number average particle diameter, a numerical value measured from a transmission electron microscope (TEM) observation image is used. That is, the diameter of a circle having the same area as the observed ultrafine particle image is defined as the particle size of the particle image. The number average particle diameter is calculated using, for example, a known image data statistical processing method using the particle diameter determined in this way, and the number of ultrafine particle images (number of statistical processing data) used for such statistical processing should be as large as possible. Is desirable. For example, in terms of reproducibility, the number of randomly selected particle images is 50 or more, preferably 80 or more, and more preferably 100 or more. Calculation of the volume% in hardened | cured material is converted with the volume of the bulb | ball which makes the particle size determined by the above a diameter.

  Conventional ordinary silica particles generally have a broad particle size distribution, for example, particles containing particles having a particle size larger than 50 nm. For this reason, the transparency is often poor and the particles tend to settle. There is also. Although what isolate | separated the particle | grains of a big particle size (what is called a cut product) is also known, there exists a tendency which is easy to carry out secondary aggregation, and most things which transparency is impaired. In that respect, according to a specific synthesis method of hydrolysis of an alkoxysilane oligomer, silica particles having a very small particle diameter can be stably obtained, and the silica particles have a property of being difficult to aggregate. There is an advantage that transparency can be obtained.

  Here, the hydrolyzate refers to a product obtained by a reaction including at least a hydrolysis reaction, and may be accompanied by dehydration condensation and the like. The hydrolysis reaction also includes a dealcoholization reaction. The alkoxysilane is a compound in which an alkoxy group is bonded to a silicon atom, and these also generate an alkoxysilane multimer (oligomer) by a hydrolysis reaction and a dehydration condensation reaction (or dealcoholization condensation). In order for the alkoxysilane oligomer to be compatible with water and a solvent described later, the alkyl chain of the alkoxysilane used in the present invention is preferably not too long, and usually has about 1 to 5 carbon atoms, preferably the carbon number. It is about 1-3. Specific examples include tetramethoxysilane and tetraethoxysilane.

  The silica particles [III] used in the present invention preferably use this alkoxysilane oligomer as a starting material. The reason why the alkoxysilane monomer (monomer) is not used as a starting material is that it is difficult to control the particle size, the particle size distribution tends to be broad, and the particle size is difficult to be uniform. This is because it is difficult to obtain the composition, and there are some kinds of monomers that are toxic, which is undesirable for safety and health. The oligomer can be produced by a known method such as the method described in JP-A-7-48454.

  Hydrolysis of the alkoxysilane oligomer is performed by adding a certain amount of water to the alkoxysilane oligomer in a specific solvent and causing a catalyst to act. Silica ultrafine particles can be obtained by this hydrolysis reaction. As the solvent, one or more kinds of alcohols, glycol derivatives, hydrocarbons, esters, ketones, ethers and the like can be used in combination. Among them, alcohols, ketones, and ethers can be used. Is particularly preferred.

  Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, octanol, n-propyl alcohol, acetylacetone alcohol and the like. Specific examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Specific examples of ethers include tetrahydrofuran, methoxypropanol, methoxybutanol and the like. In order to allow the hydrophilic silica particles to exist stably, the alkyl chains of these solvents are preferably short. Particularly preferred are methanol, ethanol, acetone, tetrahydrofuran, methoxypropanol, and methoxybutanol. Of these, tetrahydrofuran has an advantage of easily removing alcohol generated during hydrolysis of the alkoxysilane oligomer.

  The amount of water necessary for the hydrolysis reaction of the alkoxysilane oligomer is usually 0.05 times or more, more preferably 0.3 times or more the number of moles of alkoxy groups of the alkoxysilane oligomer. If the amount of water is too small, the silica particles do not grow to a sufficient size, and therefore the desired characteristics cannot be exhibited, which is not preferable. However, the upper limit is usually 1 time or less. On the other hand, if the amount is too large, the alkoxysilane oligomer tends to form a gel, which is not preferable.

  The alkoxysilane oligomer used in the present invention is preferably compatible with the solvent and water.

  As the catalyst used for the hydrolysis, one or more of metal chelate compounds, organic acids, metal alkoxides, boron compounds and the like can be used, and metal chelate compounds and organic acids are particularly preferable.

  Specific examples of the metal chelate compound include aluminum tris (acetylacetonate), titanium tetrakis (acetylacetonate), titanium bis (isopropoxy) bis (acetylacetonate), zirconium tetrakis (acetylacetonate), zirconium bis (butoxy). ) Bis (acetylacetonate), zirconium bis (isopropoxy) bis (acetylacetonate), etc., and one or more of these can be used in combination. Narto) is preferably used.

  Specific examples of the organic acid include formic acid, acetic acid, propionic acid, maleic acid and the like. Among these, one or more kinds can be used in combination, and maleic acid is particularly preferably used. When maleic acid is used, there is an advantage that a cured product obtained by performing active energy ray curing has a good hue and tends to have a small yellowness, which is preferable.

  The amount of these catalyst components to be added is not particularly limited as long as the effect is sufficiently exerted, but is usually preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight based on 100 parts by weight of the alkoxysilane oligomer. It is more than part by weight. However, even if the amount is too large, the action is not changed, so that the amount is usually preferably 10 parts by weight or less, more preferably 5 parts by weight or less based on 100 parts by weight of the alkoxysilane oligomer.

  In the present invention, as silica particles [III], silica particles made of a hydrolyzate of alkoxysilane oligomers are used, so that the particle diameter is far larger than that of silica particles generally used as a filler component. There is an advantage that fine ultrafine particles can be imparted to the active energy ray-curable composition. Moreover, since this silica particle has a property which is hard to aggregate, there also exists an advantage which can be uniformly disperse | distributed to an active energy ray hardening-type composition. Therefore, even if a large amount of silica particles is added, the active energy ray permeability is not impaired, so that a sufficient amount of silica particles can be added to enhance dimensional stability and mechanical strength. Furthermore, the silica particles obtained by such a specific production method and the surface protective effect of silica particles such as a silane coupling agent described later are used in combination, and the above urethane (meth) acrylate compound [I] and ethylenic By adding the unsaturated compound [II], there is an advantage that a larger amount of silica particles can be dispersed without agglomeration. Therefore, an active energy ray-curable resin composition having excellent properties having transparency, dimensional stability, mechanical strength, adhesion, and the like can be obtained.

  The silica particle [III] used in the present invention can protect the particle surface by surface treatment, if necessary. Usually, the silica particle [III] component, particularly the silica particles produced as described above, is highly polar and compatible with water, alcohol, etc., and the urethane (meth) acrylate compound [I] described above The ethylenically unsaturated compound [II] is not compatible. For this reason, aggregation occurs when the urethane (meth) acrylate compound [I] and the ethylenically unsaturated compound [II] are added. There is a risk of causing cloudiness. Therefore, by using a surface treatment agent having a hydrophilic functional group and a hydrophobic functional group, the surface of the silica particles is made hydrophobic, whereby the urethane (meth) acrylate compound [I] and the ethylenically unsaturated compound [ It is preferable to have compatibility with II] to prevent aggregation and cloudiness.

  As a method for surface treatment of the silica particles, a method of modifying the surface with a dispersant or a surfactant or a coupling agent is preferably used.

  The dispersant may be selected from polymer dispersants used in fine particle dispersions such as various inks, paints, and electrophotographic toners. As such a polymer dispersant, an acrylic polymer dispersant, a urethane polymer dispersant and the like are appropriately selected and used. Specific examples include “EFKA” (manufactured by Efka Additives), “Disperbyk” (manufactured by BYK Chemy (BYK)), “Disparon” (manufactured by Enomoto Kasei), and the like. The amount of the dispersant used is preferably 10 to 500% by weight, more preferably 20 to 300% by weight, based on the silica particles.

  The surfactant is not particularly limited, but can be selected from cationic, anionic, nonionic, or amphoteric polymers or low molecular weight non-aqueous surfactants. Specifically, sulfonic acid amide (“Solsperse 3000” manufactured by Avecia Pigments & Additives), hydrostearic acid (“Solsperse 17000” manufactured by Avecia Pigments & Additives), fatty acid amine, ε -Caprolactone ("Solsperse 24000") manufactured by Avecia Pigments & Additives, 1,2-hydroxystearic acid multimer, beef tallow diamine oleate ("Duomine TDO" manufactured by Lion Akzo), and the like. The amount of the surfactant used is preferably 10 to 500% by weight, more preferably 20 to 300% by weight, based on the silica particles.

  In particular, it is preferable that the silica particles made of the hydrolyzate of alkoxysilane oligomer are surface-treated with a silane coupling agent. A silane coupling agent is a compound having a structure in which an alkoxy group and an alkyl group having a functional group are bonded to a silicon atom, and has a role of making the surface of silica particles hydrophobic.

  The silane coupling agent to be used is not particularly limited as long as the purpose is achieved, but trialkoxysilane having an active energy ray-curable functional group is particularly preferable. Specific examples include epoxycyclohexylethyltrimethoxysilane, glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane. And mercaptopropyltriethoxysilane. These may be used alone or in combination of two or more.

  In this surface treatment, a Si—O—Si bond is generated through a dealcoholization reaction between the alkoxy group of the silane coupling agent and the hydroxy group on the surface of the silica particle. The amount of the silane coupling agent used is preferably 1% by weight or more of the silica particles, more preferably 3% by weight or more, and further preferably 5% by weight or more. If the amount of the silane coupling agent used is too small, the surface of the silica particles will not be sufficiently hydrophobized, which hinders uniform mixing of the urethane (meth) acrylate compound [I] and the ethylenically unsaturated compound [II]. May come. On the other hand, if the amount is too large, a large number of silane coupling components that do not bind to the silica particles will be mixed in, and it is not preferable because it tends to adversely affect the transparency and mechanical properties of the resulting cured product. Is preferably 400% by weight or less, more preferably 350% by weight or less, and still more preferably 300% by weight or less of the silica particles.

  The silane coupling agent may be partially hydrolyzed during the surface treatment of the silica particles. Accordingly, the composition after the surface treatment of the silica particles with the silane coupling agent includes a surface selected from a compound selected from the group consisting of a silane coupling agent, a hydrolysis product of the silane coupling agent, and a condensate thereof. Silica particles being treated, preferably silica particles comprising a hydrolyzate of an alkoxysilane oligomer. In addition, there may be a condensate of silane coupling agents and / or a silane coupling agent and a hydrolysis product thereof. The hydrolysis product of the silane coupling agent refers to a product in which part or all of the alkoxysilane group contained in the silane coupling agent has undergone a hydrolysis reaction to become a hydroxysilane, that is, a silanol group. For example, when the silane coupling agent is epoxycyclohexylethyltrimethoxysilane, epoxycyclohexylethylhydroxydimethoxysilane, epoxycyclohexylethyldihydroxymethoxysilane, and epoxycyclohexylethyltrihydroxysilane are the examples.

  Silane coupling agents and / or a condensate of a silane coupling agent and a hydrolysis product thereof are those in which an alkoxy group undergoes a dealcoholization reaction with a silanol group to produce a Si-O-Si bond, or a silanol group Refers to those in which a Si—O—Si bond is produced through a dehydration reaction with other silanol groups.

  In the active energy ray-curable resin composition according to the present invention, the preferable blending ratio of the silica particles [III] is 5 to 100 parts by weight, more preferably 100 parts by weight of the urethane (meth) acrylate compound [I]. Is 10 to 50 parts by weight. When the compounding ratio of the silica particles [III] is less than 5 parts by weight, the surface hardness is lowered, and when it exceeds 100 parts by weight, the composition becomes brittle or increases in shrinkage due to curing.

<Photoinitiator [V]: Component [V]>
In addition to the above components, a photopolymerization initiator [V] can be added to the active energy ray-curable resin composition according to the present invention as necessary.

  The photopolymerization initiator [V] is not particularly limited as long as it generates radicals by the action of light, and conventionally known ones can be used. For example, 4-phenoxydichloroacetophenone, 4-t- Butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylenephenyl) -2-hydroxy-2-methylpropan-1-one, 1 -(4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenylketone, 2 -Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, benzoin, Zoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyldimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, camphorquinone, dibenzosuberone, 2 -Ethyl anthraquinone, 4 ', 4 "-diethylisophthalophenone, 3,3', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, α-acy Roxime ester, acylphosphine oxide, methylphenylglyoxylate, benzyl, 9,10-phenanthrenequinone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, etc. Among them, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1-phenylpropane- 1-one is preferably used, and these can be used alone or in combination of two or more.

  Further, triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4 as an auxiliary of photopolymerization initiator [V], 4 -Ethyl dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4 -It is also possible to use together 1 type, or 2 or more types, such as diisopropyl thioxanthone.

  The blending amount of the photopolymerization initiator [V] in the active energy ray-curable resin composition according to the present invention includes urethane (meth) acrylate compound [I], ethylenically unsaturated compound [II], and silica particles. The total of [III] (when urethane (meth) acrylate compound [IV] is included, further include urethane (meth) acrylate compound [IV])) 0.01 to 20 parts by weight with respect to 100 parts by weight Is preferable, more preferably 0.05 to 10 parts by weight, and particularly preferably 0.1 to 8 parts by weight. When the blending amount is less than 0.01 parts by weight, it is extremely difficult to sufficiently cure. When the blending amount exceeds 20 parts by weight, the polymerization reaction proceeds rapidly and not only increases the optical distortion but also deteriorates the hue. There is a case.

<Other ingredients>
The active energy ray-curable resin composition according to the present invention includes urethane (meth) acrylate compound [I], ethylenically unsaturated compound [II], silica particles [III], and other urethane (meth) acrylate compounds. In addition to [IV] and photopolymerization initiator [V], antioxidants, polymerization inhibitors, yellowing inhibitors, ultraviolet absorbers, fillers, dyes and pigments, oils, plasticizers, waxes, desiccants, Dispersing agents, wetting agents, emulsifying agents, gelling agents, stabilizers, antifoaming agents, leveling agents, thixotropic agents, flame retardants, fillers, reinforcing agents, matting agents, crosslinking agents, etc. can also be added. is there.

  The active energy ray-curable resin composition according to the present invention preferably contains substantially no solvent. However, from the viewpoint of ensuring viscosity adjustment, smoothness as a coating agent, uniformity, and the like, it is an organic solvent. May be blended. Examples of such organic solvents include ethyl acetate, butyl acetate, toluene, xylene, methanol, ethanol, propanol, butanol, acetone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cellosolves, diacetone alcohol, and the like. These can be used alone or in combination of two or more.

[Method for producing active energy ray-curable resin composition]
The method for producing the active energy ray-curable resin composition according to the present invention uses a urethane (meth) acrylate compound [I], an ethylenically unsaturated compound [II] and silica particles [III], and further, if necessary. The urethane (meth) acrylate compound [IV], the photopolymerization initiator [V], and other components that are uniformly dispersed and mixed are not particularly limited. Specifically,
(1) A method of preparing a powder of component [III], applying an appropriate surface treatment and then directly dispersing it in component [I] and component [II]. (2) Liquid of component [I] and component [II] Method of synthesizing component [III] in (3) Preparing component [III] in a liquid medium, mixing component [I] and component [II] in the liquid medium, and then removing the volatile liquid medium Method (4) Method of mixing component [I] and component [II] in a liquid medium, preparing component [III] in the liquid medium and then removing the volatile liquid medium (5) Component in the liquid medium Examples include a method of synthesizing [III] and component [I], mixing component [I] and component [III], adding component [II], and then removing the volatile liquid medium. Among these, the method (3) is most preferable because it is easy to obtain a product having high transparency and good storage stability.

  The method of mixing the urethane (meth) acrylate compound [IV] used as necessary is not particularly limited as long as it is a method of uniformly dispersing and mixing, but the component [I] and / or component [II] is not limited. It is preferable to mix. The method of mixing the photopolymerization initiator [V] and other components is not particularly limited as long as they are uniformly dispersed and mixed and no side reaction occurs, but they are mixed before or after the removal of the volatile liquid medium. Is preferred. Before the removal of the volatile liquid medium, the viscosity is low, the workability is good, and the solubility is good and preferable. On the other hand, after removal, it is preferable in terms of suppressing side reactions.

Specifically, the method (3) is as follows.
(A) A step of hydrolyzing an alkoxysilane oligomer at a temperature of 10 to 100 ° C. in a liquid medium such as a solvent, a surface treatment agent or a diluent to synthesize silica particles. It is preferable to sequentially perform the step of c) mixing component [I] and component [II] and (d) removing the volatile liquid medium at a temperature of 10 to 75 ° C. According to this production method, an active energy ray-curable resin composition in which ultrafine silica particles having a uniform particle diameter are highly dispersed can be obtained more easily.

  In the step (a), an alkoxysilane oligomer, a catalyst and water are added in a liquid medium to hydrolyze the alkoxysilane oligomer to synthesize silica particles. The liquid medium is not particularly limited, but is preferably compatible with component [I] and component [II]. Specifically, a solvent, a surface treatment agent or a diluent is used. The surface treatment agent and diluent are the same as described above. As the solvent, alcohols, ketones or ethers are preferably used, and particularly preferably, one or more of alcohols having 1 to 4 carbon atoms, acetone, methyl ethyl ketone, tetrahydrofuran, methoxypropanol, and methoxybutanol are used. It is done. The amount of the liquid medium is preferably 0.3 to 10 times the weight of the alkoxysilane oligomer.

  Examples of the catalyst include organic acids such as formic acid and maleic acid; inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid; and hydrolysis catalysts such as metal complex compounds such as acetylacetone aluminum, dibutyltin dilaurate and diztiltin dioctate. . The amount used is preferably 0.1 to 10% by weight based on the alkoxysilane oligomer.

  10 to 50% by weight of water is preferably added to the alkoxysilane oligomer.

  The hydrolysis temperature is 10 to 100 ° C. If the temperature is lower than this, the reaction for forming silica particles does not proceed sufficiently, which is not preferable. On the other hand, if it is too high, gelation or white turbidity of the oligomer tends to occur, which is not preferable. The hydrolysis time is preferably 30 minutes to 1 week.

  The reaction (b) is a step of protecting the surface of the silica particles, and examples of the surface protective agent include the aforementioned surfactants, dispersants, silane coupling agents and the like.

  When using a surfactant and / or dispersant as the surface protective agent, a method of adding a surface protective agent and stirring and reacting at room temperature to 60 ° C. for about 30 minutes to 2 hours, surface protective agent And the like, followed by aging for several days at room temperature. When adding the surface protective agent, it is important not to select a solvent with a very high solubility of the surface protective agent. When a solvent having a very high solubility of the surface protective agent is used, it is not preferable because the protection to the silica particles is not sufficiently performed or a long time is required for the protection process. In the case of a solvent having a very high solubility of the surface protective agent, for example, when a solvent having a difference in solubility value (SP value) between the solvent and the surface treatment agent of 0.5 or more is used, protection to the silica particles is achieved. Often done well.

  When a silane coupling agent is used, the surface protection reaction proceeds at room temperature (about 25 ° C.). Usually, stirring is performed for 0.5 to 24 hours to allow the reaction to proceed, but heating may be performed at a temperature of 75 ° C. or lower. When heated, the reaction rate increases and the reaction can be carried out in a shorter time. However, if the temperature is too high, the reaction of the functional group of the silane coupling agent occurs and gelation tends to occur, which is not preferable. When a silane coupling agent is used, water may be added. Water is usually added in the range of the amount necessary for hydrolysis of the alkoxy group derived from the silane coupling agent and the remaining alkoxy group derived from the alkoxysilane.

  The silane coupling agent may be added in multiple portions. In that case, water may be added in a plurality of times, and the amount thereof is the same as that described in the amount of water added to the silane coupling agent.

The step (c) needs to be performed after the reaction (b) is sufficiently completed. The confirmation can be performed by measuring the residual amount of the silane coupling agent in the reaction solution. Usually, the reaction is terminated when the remaining amount of the silane coupling agent in the reaction solution becomes 10% by weight or less with respect to the charged amount. If the operation (c) is performed before the reaction (b) sufficiently proceeds, the monomers and oligomers are not mixed uniformly, and the composition becomes unclear in the subsequent step, which is not preferable.
The step (c) can be performed at room temperature (25 ° C.). However, when the viscosity of the monomer or oligomer is high, or when the melting point of the monomer or oligomer is room temperature (25 ° C.) or higher, the temperature is 30 to 90 ° C. You may carry out by heating. The mixing time is preferably 30 minutes to 5 hours.

  In the step (d), the solvent such as the solvent used as a liquid medium and the alcohol produced by hydrolysis of the alkoxysilane oligomer is mainly removed. However, these may be removed within a necessary range, and may not be completely removed. In addition, it is preferable that processing temperature shall be the range of 10-75 degreeC. If the temperature is lower than this range, the solvent is not sufficiently removed, which is not preferable. Conversely, when too high, since a composition becomes easy to gelatinize, it is unpreferable. The temperature may be controlled step by step. The removal time is preferably 1 to 12 hours. Moreover, it is preferable to remove under reduced pressure of 20 kPa or less, more preferably 10 kPa or less, and still more preferably 2 kPa or less. The pressure may be gradually reduced.

  According to the preferred production method described above, the particle size is smaller in the composition than in the method in which the silica particles or silica particles treated with a surface treatment agent such as a silane coupling agent are dispersed in the resin composition. There is an advantage that a large amount of ultrafine particles can be dispersed without agglomeration. Therefore, the obtained active energy ray-curable resin composition is obtained by dispersing a sufficient amount of silica particles to increase the dimensional stability and mechanical strength of the resin without impairing the active energy ray permeability. And the active energy ray hardened | cured material obtained by hardening it has transparency, high surface hardness, and low cure shrinkage. Preferably, in addition, there is an advantage of having both dimensional stability and adhesion, and more preferably having excellent surface curability.

[Physical properties of active energy ray-curable resin composition]
The active energy ray-curable resin composition according to the present invention is preferably a liquid having a low viscosity at room temperature. If the composition is solid at room temperature or is a high-viscosity liquid, workability during application of the composition is significantly reduced, which is not preferable.

  The upper limit of the preferable range of the viscosity at 25 ° C. of the active energy ray-curable resin composition according to the present invention is 10.0 Pa · s, more preferably 7.0 Pa · s, and the lower limit is 0.5 Pa · s. Preferably, it is 1.0 Pa · s. If the viscosity is higher than this range, various coating methods, especially spin coating, may cause coating defects such as uneven film thickness, uneven coating, crater defects, crushed skin, shark skin, etc. This is not preferable. On the other hand, if the viscosity is too low, it is not preferable because it is difficult to control the film thickness when a large layer having a film thickness of several tens of μm or more is formed.

[Physical properties of cured active energy rays]
The active energy ray-cured product obtained from the active energy ray-curable resin composition according to the present invention usually exhibits insoluble and infusible properties in a solvent or the like, and can be used for an optical recording medium even when it is thickened. It is preferable that it has advantageous properties and is excellent in adhesion and surface hardening. Specifically, it is preferable to exhibit low optical distortion (low birefringence), high light transmittance, dimensional stability, high adhesion, high degree of surface curing, and a certain level of heat resistance. Further, the smaller the curing shrinkage, the better.

  Regarding the transparency of the cured active energy ray, the light transmittance per optical path length of 0.1 mm at 550 nm is preferably 80% or more, more preferably 85% or more, and still more preferably 89% or more. More preferably, the light transmittance per optical path length of 0.1 mm at 400 nm is preferably 80% or more, more preferably 85% or more, and still more preferably 89% or more. The light transmittance may be measured at room temperature using, for example, an HP8453 ultraviolet / visible absorptiometer manufactured by Hewlett-Packard Company.

  Moreover, it is preferable that the surface hardness by the pencil hardness test based on JISK5400 is HB or more, More preferably, it is F or more, More preferably, it is H or more. Moreover, it is preferable that it is 7H or less. In this case, the cured product preferably satisfies the above-mentioned hardness even in a cured product cured on an inorganic substrate such as glass or metal, and also in the cured product cured on a plastic substrate such as polycarbonate. It is preferable to satisfy. If the hardness is too small, it is not preferable because the surface is easily scratched. Although there is no problem with the hardness being too large, the cured product tends to become brittle, and cracks and peeling are likely to occur, which is not preferable.

  Furthermore, curing shrinkage is preferably as small as possible, and is usually 3% by volume or less, more preferably 2% by volume or less. For convenience, this curing shrinkage is replaced by a method in which an active energy ray-curable resin composition is applied on a substrate and the amount of concave warpage generated after curing is measured. The measuring method is to form a composition film with a thickness of 100 ± 5 μm on a circular polycarbonate plate having a diameter of 130 mm and a thickness of 1.2 ± 0.2 mm using a spin coater, and irradiate a prescribed amount of active energy rays. Then, leave it on the surface plate for 1 hour. After standing, the concave warp of the polycarbonate plate caused by the curing shrinkage of the composition is measured. The concave warp is preferably 1 mm or less, more preferably 0.5 mm or less.

In addition, it is preferable that the adhesion of the active energy ray cured product to the substrate is high. This adhesion measuring method is, for example, by forming a coating film of 100 ± 5 μm by spin coating on a 10 cm square optically polished glass plate, irradiating active energy rays of 1 J / cm ² , and then 1 at room temperature. Leave for hours. A 3 cm long cut is made in the center of the cured composition so as to reach the glass surface with a cutter knife, and after standing for another 14 days at room temperature, peeling of the interface between the cured product of the cut and the glass surface is visually observed. Can be evaluated by whether or not. When the number of samples is 5 and no peeling is observed for all the samples, ◎ when no peeling is observed for two or more samples, ○ when no peeling is observed for only one sample, Δ, all The case where peeling was visually observed for the sample of can be evaluated as x. The degree of adhesion is preferably ◯ or ◎, and more preferably ◎. Moreover, what has the said adhesiveness with a plastic substrate, such as a polycarbonate, is further more preferable than on an optical polishing glass plate.

  In addition, the hardened surface of the active energy ray cured product is preferably hard. This hardness is measured by irradiating a specified amount of active energy rays, and with the right index finger and thumb wearing rubber gloves, the sample is lightly sandwiched so that the thumb is on the application surface side, and the thumb is separated from the application surface. The case where the trace is not observed visually is measured as ◯, the case where the trace is observed thinly, Δ, and the case where the trace is observed deeply as ×. The surface hardness is preferably ◯.

  Moreover, it is preferable that this active energy ray hardened | cured material does not melt | dissolve with respect to various solvents. Typically, it is preferable not to dissolve in a solvent such as toluene, chloroform, acetone, or tetrahydrofuran.

[Method for producing cured active energy ray]
The active energy ray-curable resin composition according to the present invention is cured by irradiating active energy rays to obtain an active energy ray cured product. As such active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used. Curing by ultraviolet irradiation is advantageous from the viewpoint of easy availability and price.

As a method of curing by ultraviolet irradiation, 0.01 to 10 J / cm using a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, etc. that emit light in a wavelength range of 150 to 450 nm. ^It is sufficient to irradiate about ² times. After the ultraviolet irradiation, heating can be performed as necessary to complete the curing.

  In addition, the atmosphere at the time of curing the active energy ray at the time of curing the composition of the present invention may be air or an inert gas such as nitrogen or argon.

[Use of cured active energy rays]
The active energy ray cured product according to the present invention is excellent in low shrinkage, surface hardness, and environmental resistance, and thus is preferably used for an optical recording medium material.

[Optical recording medium]
The optical recording medium referred to in the present invention is not particularly limited, but a next-generation high-density optical recording medium using a blue laser is preferable. As the optical recording medium, light on which a protective film is formed on a surface on which a dielectric film, a recording film, a reflective film, etc. (hereinafter, these layers are collectively referred to as “recording / reproducing functional layer”) is formed. The recording medium means an optical recording medium using a laser beam having a wavelength of 380 to 800 nm, preferably a laser beam having a wavelength of 450 to 350 nm.

The coating agent for an optical recording medium of the present invention is preferably used for a protective layer in the optical recording medium.
The protective layer is made of a cured product obtained by spin-coating the active energy ray-curable resin composition according to the present invention described above and usually curing it, and is provided in contact with the recording / reproducing functional layer.

  The transmittance of the protective layer thus formed needs to be usually 80% or more, preferably 85% or more, more preferably 89% or more at the wavelength of light used for recording / reproduction. Within such a range, loss due to absorption of recording / reproducing light can be minimized. On the other hand, the transmittance is most preferably 100%, but is usually 99% or less because of the performance of the material used.

  The protective layer desirably has a property that protects the recording / reproducing functional layer from water and dust.

  In addition, the surface hardness of the protective layer is preferably HB or more, more preferably F or more, particularly preferably H or more, particularly preferably 7H or less, according to the pencil hardness test according to JIS K5400. Is preferred. If the hardness is too small, it is not preferable because the surface is easily scratched. Although there is no problem with the hardness being too large, the cured product tends to become brittle, and cracks and peeling are likely to occur, which is not preferable.

  Furthermore, it is preferable that the adhesion between the protective layer and the recording / reproducing functional layer is high. Further, it is preferable that the curing shrinkage is small. About this adhesiveness and hardening shrinkage, it is as having demonstrated in the term of the physical property of the above-mentioned active energy ray hardening-type resin composition.

  The thickness of the protective layer is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, still more preferably 70 μm or more, and particularly preferably 85 μm or more. If the film thickness is in such a range, the influence of dust and scratches adhering to the surface of the protective layer can be reduced, and the thickness should be sufficient to protect the recording / reproducing functional layer from moisture in the outside air. Can do. On the other hand, the thickness of the protective layer is usually 300 μm or less, preferably 130 μm or less, more preferably 115 μm or less. When the film thickness is within this range, a uniform film thickness can be easily formed by a general coating method used in spin coating or the like. The protective layer is preferably formed with a uniform film thickness in a range covering the recording / reproducing functional layer.

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

Example 1
[Production of Aliphatic Copolycarbonate Diol (a2-1)]
1,6-hexanediol and 1,5-pentanediol were charged into the reactor at a molar ratio of 5: 5, and phosgene was introduced to obtain an aliphatic copolycarbonate diol (a2-1).
The obtained aliphatic copolycarbonate diol (a2-1) had a hydroxyl value of 139.5 KOH-mg / g, a molecular weight of 800, and a viscosity of 1020 mPa · s / 50 ° C.

[Production of urethane (meth) acrylate compound [I-1]]
A four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer was charged with 310.0 g of hydrogenated xylene diisocyanate (B-1) (hydrolyzable chlorine content = 100 ppm). The temperature was raised to 80 ° C., and a mixture of 428.0 g of aliphatic copolycarbonate diol (a2-1), 39.5 g of 2,2-bis (hydroxymethyl) butyric acid (a3-1) and 0.1 g of dibutyltin dilaurate (A-1) was dropped at an internal temperature of 80 to 90 ° C. over about 5 hours, and when the remaining isocyanate group reached 8.63%, 0.4 g of di-t-butylhydroxyphenol was mixed. -Hydroxyethyl acrylate (C-1) (222.4 g) was added and allowed to react for 12 hours. When the residual isocyanate group reached 0.3%, the reaction was terminated and urethane (meta To give the acrylate compound [I-1].
The obtained urethane (meth) acrylate compound [I-1] had a weight average molecular weight of 4640 and an acid value of 14.9 KOH-mg / g.

[Preparation of tetramethoxysilane oligomer]
After mixing 234 g of tetramethoxysilane and 74 g of methanol, 22.2 g of 0.05% hydrochloric acid was added, and a hydrolysis reaction was performed at 65 ° C. for 2 hours. Next, the system temperature was raised to 130 ° C., and the produced methanol was removed, and then the temperature was gradually raised to 150 ° C. while blowing nitrogen gas, and the tetramethoxysilane monomer was removed by keeping it for 3 hours.

[Preparation of silica particles [III-1]]
After 312 g of methanol was added to 154 g of the tetramethoxysilane oligomer obtained by the above operation and stirred uniformly, 1.54 g of acetylacetone aluminum was dissolved as a catalyst. To this solution, 32.6 g of demineralized water was gradually added dropwise with stirring, and the mixture was stirred at 60 ° C. for 2 hours to grow silica particles. The diameter of the produced silica particles was estimated to be 2 to 5 nm by morphological observation using a TEM electron microscope.

[Hydrophobization treatment of silica particle surface with silane coupling agent]
After adding 12 g of acryloxypropyltrimethoxysilane as a silane coupling agent to 40 g of the alcohol solution of silica particles obtained by the above operation and stirring for 2 hours at room temperature, the silane coupling agent is brought into contact with the surface of the silica particles. Then, 5.4 g of demineralized water and 12 g of acryloxypropyltrimethoxysilane were gradually added to modify the silica particle surface to obtain 69.4 g of a silane-treated silica particle solution [III-1a].

[Mixing and solvent removal]
53.2 g of the silane-treated silica particle solution [III-1a] was taken, 46.3 g of urethane (meth) acrylate compound [I-1] was added thereto, and isobornyl acrylate [II] as ethylenically unsaturated compound [II]. II-1] 23.2 g, 2-hydroxyethyl acrylate [II-2] 7.7 g, and 1-hydroxycyclohexyl phenyl ketone [V-1] 2.7 g as a photopolymerization initiator [V] were added. The mixture was stirred at room temperature for 2 hours to obtain a transparent curable resin composition.

  Low boiling components contained in the curable resin composition were removed by evaporation at 50 ° C. for 2 hours under reduced pressure. The following evaluation was performed about the obtained composition.

〔viscosity〕
The viscosity at 25 ° C. was measured using an E-type viscometer.

[Applicability]
When spin coating is performed by dropping 2 g of the resin composition on a circular polycarbonate plate having a diameter of 130 mm and a thickness of 1.2 mm and silicon nitride is sputter-deposited, ◯ indicates that there is no unpainted residue or repellency. Or the case where repelling occurred was set as x.

〔transparency〕
A resin composition is applied on a 100 × 100 × 3 mm glass plate by spin coating to a thickness of 100 ± 5 μm, and then irradiated with 1 J / cm ² of ultraviolet light from a distance of 15 cm with a high-pressure mercury lamp. Was cured and cooled for 1 hour. The light transmittance at 550 nm of this cured product-formed glass plate was measured using a spectrometer and evaluated.

〔surface hardness〕
A resin composition is applied to a polyethylene terephthalate film having a thickness of 100 ± 5 μm with a bar coater to a thickness of 100 ± 5 μm, and then irradiated with 1 J / cm ² of ultraviolet light from a distance of 15 cm with a high-pressure mercury lamp. Cured and cooled for 1 hour. It measured by the pencil hardness test based on JISK5400 of this hardened | cured material surface.

[Adhesion]
On a 10 cm square optically polished glass plate, 15 drops of the resin composition were dropped using a dropper and left at room temperature for 1 minute, and then placed between a metal halide lamp with an output of 80 W / cm installed vertically at a distance of 40 cm. The composition was cured by irradiating with ultraviolet rays for 5 minutes (irradiation intensity was 1.5 J / cm ² ), and left at room temperature for 1 hour. A cut is made in the center of the cured composition part with a cutter knife so as to reach the glass surface, and after standing for another 14 days at room temperature, is peeling of the interface between the cured product of the cut part and the glass surface observed visually? It was evaluated by how. When the number of samples is 5 and no peeling is observed for all the samples, ◎ when no peeling is observed for two or more samples, ○ when no peeling is observed for only one sample, Δ, all The case where peeling was visually observed with respect to the sample was marked with ×.

[Curing shrinkage]
A resin composition film having a thickness of 100 ± 5 μm is formed on a circular polycarbonate plate having a diameter of 130 mm and a thickness of 1.2 mm by using a spin coater, and an output of 80 W / cm installed at a distance of 15 cm from this film. Were irradiated with ultraviolet rays for 30 seconds (irradiation intensity was 1 J / cm ² ), and then allowed to stand on a surface plate for 1 hour. After standing, the concave warp of the polycarbonate plate caused by curing shrinkage of the composition was measured. The gap gauge was used for the measurement, and the floating amount (mm) from the surface plate was measured at four locations on the polycarbonate plate end, and the average value was taken as the curing shrinkage value (mm).

(Environment resistance)
The concave warp of the polycarbonate plate generated after the heat and humidity resistance test at 80 ° C., 85%, 200 hr was measured by the same method as the curing shrinkage.

Example 2
[Production of urethane (meth) acrylate compound [I-2]]
308.6 g of isophorone diisocyanate (B-2) (hydrolyzable chlorine content = 5 ppm) was charged into a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, and an internal temperature of 80 ° C. The polyoxypropylene glycol (a1-1) having a number average molecular weight of 1000 (Sanyo Chemical Industries, “Sanix PP-1000”) 463.7 g and 2,2-bis (hydroxymethyl) butyric acid ( a3) A mixture (A-2) of 34.3 g and 0.1 g of dibutyltin dilaurate was dropped at an internal temperature of 80 to 90 ° C. over about 5 hours, and when the residual isocyanate group became 7.23% Then, 193.4 g of 2-hydroxyethyl acrylate (C-1) mixed with 0.4 g of di-t-butylhydroxyphenol was added and reacted for 12 hours. The reaction was terminated when the sulfonate group became 0.3%, obtaining a urethane (meth) acrylate compound [I-2].
The obtained urethane (meth) acrylate compound [I-2] had a weight average molecular weight of 3750 and an acid value of 12.9 KOH-mg / g.

[Preparation and evaluation of resin composition]
A transparent curable resin composition was obtained in the same manner as in Example 1 except that the urethane (meth) acrylate compound [I-2] was used instead of the urethane (meth) acrylate compound [I-1]. About the obtained transparent resin composition, evaluation similar to Example 1 was performed.

Example 3
[Production of urethane (meth) acrylate compound [I-3]]
A four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer was charged with 293.0 g of hydrogenated xylene diisocyanate (B-1) and the temperature was raised to an internal temperature of 80 ° C. 251.9 g of polyoxypropylene glycol (a1-1) having an average molecular weight of 1000 (manufactured by Sanyo Chemical Industries, “Sanniks PP-1000”) and the aliphatic copolycarbonate diol (a2-1) 207 produced in Example 1 7 g, a mixture (A-3) of 2,2-bis (hydroxymethyl) butyric acid (a3-1) 37.0 g and dibutyltin dilaurate 0.1 g at an internal temperature of 80 to 90 ° C. over about 5 hours When the residual isocyanate group was 8.02% by dropwise addition, 2-hydroxyethyl acrylate (C) mixed with 0.4 g of di-t-butylhydroxyphenol was added. 1) was reacted for 12 hours by adding 210.2 g, residual isocyanate groups is complete the reaction when it becomes 0.3% to obtain a urethane (meth) acrylate compound [I-3].
The obtained urethane (meth) acrylate compound [I-3] had a weight average molecular weight of 4700 and an acid value of 13.4 KOH-mg / g.

[Preparation and evaluation of resin composition]
A transparent curable resin composition was obtained in the same manner as in Example 1 except that the urethane (meth) acrylate compound [I-3] was used instead of the urethane (meth) acrylate compound [I-1]. About the obtained transparent resin composition, evaluation similar to Example 1 was performed.

Example 4
[Production of urethane (meth) acrylate compound [I-4]]
Charged 350.8 g of hydrogenated xylene diisocyanate (B-1) into a four-necked round bottom flask equipped with a reflux condenser, stirrer, nitrogen gas inlet and thermometer, and raised the internal temperature to 80 ° C. 298.5 g of the aliphatic copolycarbonate diol (a2-1) prepared in Example 1, 11.3 g of 2,2-bis (hydroxymethyl) butyric acid (a3-1), and neopentyl glycol (a4-1) 37. 5 g and a mixture (A-4) of dibutyltin dilaurate 0.1 g were dropped at an internal temperature of 80 to 90 ° C. over about 5 hours, and when the residual isocyanate group became 13.05%, di-t- 301.9 g of 2-hydroxyethyl acrylate (C-1) mixed with 0.4 g of butylhydroxyphenol was added and reacted for 12 hours, resulting in a residual isocyanate group of 0.3%. The reaction was terminated at a point, to obtain a urethane (meth) acrylate compound [I-4].
The urethane (meth) acrylate compound [I-4] obtained had a weight average molecular weight of 2800 and an acid value of 14.1 KOH-mg / g.

[Preparation and evaluation of resin composition]
A transparent curable resin composition was obtained in the same manner as in Example 1 except that the urethane (meth) acrylate compound [I-4] was used instead of the urethane (meth) acrylate compound [I-1]. About the obtained transparent resin composition, evaluation similar to Example 1 was performed.

Example 5
[Production of urethane (meth) acrylate compound [I-5]]
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 339.6 g of isophorone diisocyanate (B-2) was charged and the internal temperature was raised to 80 ° C. Mixture (A-5) of manufactured aliphatic copolycarbonate diol (a2-1) 409.7g, 2,2-bis (hydroxymethyl) butyric acid (a3-1) 37.8g, and dibutyltin dilaurate 0.1g Was added dropwise at an internal temperature of 80 to 90 ° C. over about 5 hours, and when the residual isocyanate group reached 8.16%, 2-hydroxyethyl acrylate (0.4 g) mixed with 0.4 g of di-t-butylhydroxyphenol ( C-1) 212.9 g was added and allowed to react for 12 hours. When the residual isocyanate group reached 0.3%, the reaction was terminated and the urethane (meth) acrylate was made. To give things [I-5].
The obtained urethane (meth) acrylate compound [I-5] had a weight average molecular weight of 4740 and an acid value of 14.2 KOH-mg / g.

[Preparation and evaluation of resin composition]
A transparent curable resin composition was obtained in the same manner as in Example 1 except that the urethane (meth) acrylate compound [I-5] was used instead of the urethane (meth) acrylate compound [I-1]. About the obtained transparent resin composition, evaluation similar to Example 1 was performed.

Comparative Example 1
[Production of urethane (meth) acrylate compound [I-6]]
A four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer was charged with 416.8 g of isophorone diisocyanate (B-2) to an internal temperature of 80 ° C., and the number average molecular weight was A mixture (A-6) of 850 polytetramethylene glycol (a4-2) 265.7 g, 1,4-butanediol (a4-3) 37.5 g and dibutyltin dilaurate 0.1 g was used at an internal temperature of 80 to 2-hydroxyethyl acrylate (C-1) 261. mixed with 0.4 g of di-t-butylhydroxyphenol at the time when the reaction was performed dropwise at 90 ° C. over about 5 hours and the residual isocyanate group was 10.67%. 3 g was added and reacted for 12 hours. When the residual isocyanate group became 0.3%, the reaction was terminated, and the urethane (meth) acrylate compound [I-6] Obtained.
The obtained urethane (meth) acrylate compound [I-6] had a weight average molecular weight of 3560 and an acid value of 0.3 KOH-mg / g.

[Preparation and evaluation of resin composition]
A transparent curable resin composition was obtained in the same manner as in Example 1 except that the urethane (meth) acrylate compound [I-6] was used instead of the urethane (meth) acrylate compound [I-1]. About the obtained transparent resin composition, evaluation similar to Example 1 was performed.

Comparative Example 2
[Production of Aliphatic Polycarbonate Diol (a2′-2)]
1,6-hexanediol was charged into the reactor, and phosgene was introduced to obtain an aliphatic polycarbonate diol (a2′-2).
The obtained aliphatic polycarbonate diol (a2′-2) had a hydroxyl value of 112 KOH-mg / g, a molecular weight of 1000, and a viscosity of 2100 mPa · s / 50 ° C.

[Production of urethane (meth) acrylate compound [I-7]]
308.5 g of isophorone diisocyanate (B-2) was charged into a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, and the temperature was raised to an internal temperature of 80 ° C. A mixture (A-7) of (a2′-2) 463.7 g, 2,2-bis (hydroxymethyl) butyric acid (a3-1) 34.3 g, and dibutyltin dilaurate 0.1 g was used at an internal temperature of 80 to 90. When the reaction was conducted dropwise at about 5 hours over a period of about 5 hours to reach 7.23% of the remaining isocyanate groups, 193.4 g of 2-hydroxyethyl acrylate (C-1) mixed with 0.4 g of di-t-butylhydroxyphenol Was added and allowed to react for 12 hours. When the residual isocyanate group reached 0.3%, the reaction was terminated to obtain urethane (meth) acrylate compound [I-7].
The obtained urethane (meth) acrylate compound [I-7] had a weight average molecular weight of 4880 and an acid value of 12.5 KOH-mg / g.

[Preparation and evaluation of resin composition]
A transparent curable resin composition was obtained in the same manner as in Example 1 except that the urethane (meth) acrylate compound [I-7] was used instead of the urethane (meth) acrylate compound [I-1]. About the obtained transparent resin composition, evaluation similar to Example 1 was performed.

  The evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 1.

  From Table 1, it can be seen that the coating agent for optical recording media of the present invention is excellent in all of applicability, transparency, surface hardness, adhesion, curing shrinkage, and environmental resistance.

The coating agent for optical recording media of the present invention has low viscosity, good coating workability, high surface hardness, low curing shrinkage, transparency, adhesion, moisture resistance, heat resistance, and other environmental resistance. It is very useful as an excellent coating agent, and particularly useful as a coating agent for forming a protective layer of an optical recording medium.
The optical recording medium of the present invention having such a cured product layer, particularly a protective layer, with the coating agent for optical recording medium of the present invention is useful as a next generation high density optical recording medium using various optical recording media, particularly blue laser. is there.

Claims (12)

It is composed of polyoxypropylene glycol (a1) having a number average molecular weight of 300 to 2000 and / or repeating units (i) and (ii) below, and the ratio (molar ratio) between (i) and (ii) is 9: A polyol component (A) comprising an aliphatic copolycarbonate diol (a2) having a number average molecular weight of 300 to 2000 and a carboxyl group-containing polyol (a3),
Polyisocyanate component (B)
And hydroxyl-containing (meth) acrylate component (C)
Urethane (meth) acrylate compound [I] obtained by reacting
An ethylenically unsaturated compound [II],
A coating agent for an optical recording medium comprising an active energy ray-curable resin composition containing silica particles [III].

(In the formula, R ¹ and R ² , and R ³ and R ⁴ may be the same or different, and are H or CH ₃ , and 1 ≦ n ≦ 4, 1 ≦ m ≦ 4.)   The urethane (meth) acrylate compound [I] contains a polyol component (a4) other than the (a1) to (a3) as the polyol component (A). Coating agent for optical recording media.   The coating agent for an optical recording medium according to claim 2, wherein the polyol component (a4) is a low molecular weight polyol having a number average molecular weight of 300 or less.   The coating agent for optical recording media according to any one of claims 1 to 3, wherein the polyisocyanate component (B) is at least one selected from isophorone diisocyanate and hydrogenated xylene diisocyanate. .   The coating agent for optical recording media according to any one of claims 1 to 4, wherein the acid value of the urethane (meth) acrylate compound [I] is 1.5 to 50 KOH-mg / g.   The optical recording medium according to any one of claims 1 to 5, wherein the ethylenically unsaturated compound [II] contains an alicyclic (meth) acrylate monomer having a glass transition point (Tg) of 0 ° C or higher. Coating agent.   10 to 150 parts by weight of ethylenically unsaturated compound [II] and 5 to 100 parts by weight of silica particles [III] are contained per 100 parts by weight of urethane (meth) acrylate compound [I]. The coating agent for optical recording media according to any one of claims 1 to 6.   The active energy ray-curable resin composition contains a urethane (meth) acrylate compound [IV] other than the urethane (meth) acrylate compound [I]. The coating agent for optical recording media as described.   The urethane (meth) acrylate compound [IV] contains a urethane (meth) acrylate compound obtained by reacting a polyisocyanate component (B) and a hydroxyl group-containing (meth) acrylate component (C). 8. The coating agent for optical recording media according to 8.   The coating agent for an optical recording medium according to any one of claims 1 to 9, wherein the silica particles [III] contain an oligomer hydrolyzate of alkoxysilane.   The coating composition for optical recording media according to any one of claims 1 to 10, wherein the active energy ray-curable resin composition contains a photopolymerization initiator [V].   The optical recording medium which has a hardened | cured material layer which consists of a coating agent for optical recording media as described in any one of Claims 1 thru | or 11.