JP2010180300A - Active energy ray hardening composition, hardened body and laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray hardening composition capable of giving a laminate small in deformation right after radical change of environmental temperature or environmental humidity and having sufficient surface hardness and excellent wear resistance and load marking resistance. <P>SOLUTION: The active energy ray hardening composition contains compounds (A), (B) of urethane (metha) acrylate oligomers each having a specific structure, wherein the ratio (A)/(B) by weight of the content of the compounds (A) and (B) in the composition is 2.0-7.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an active energy ray-curable composition containing a urethane (meth) acrylate oligomer having a specific structure, a cured product obtained by irradiating the composition with active energy rays, and a laminate having a cured film composed thereof.

  In recent years, optical information recording media such as read-only optical discs and optical recording discs have been widely used as information recording media for recording or storing vast amounts of information such as moving image information. As one of them, for example, a high-density type optical disc (so-called Blu-ray disc, hereinafter sometimes referred to as “Blu-ray disc”) using a laser beam having a wavelength of 400 nm has been proposed (see Patent Document 1). The Blu-ray Disc is an optical recording medium having a resin substrate, a recording / reproducing functional layer, a protective layer, and a hard coat layer in this order. The hard coat layer is required to have scratch resistance and hardness. On the other hand, the entire disk is required to be able to read and write information stably even if the environment such as temperature and humidity changes. For example, after storing for a certain period of time under high temperature and high humidity, after returning to room temperature One of the required performances is that the deformation of the disk after a certain period of time is small, and among them, it is important to reduce the warpage of the disk that particularly affects the reading and writing of information.

  On the other hand, Patent Document 2 discloses urethane (Metal) as an active energy ray-curable composition that is excellent in transparency, abrasion resistance, recording film protection, and mechanical properties, and also excellent in heat resistance and moisture deformation resistance. ) An active energy ray-curable composition containing an acrylate is disclosed, and an optical recording medium using the active energy ray-curable composition has been proposed. In Patent Document 2, it is reported that the optical recording medium is less deformed after being stored at high temperature and high humidity for a long time and then returned to room temperature and stored for a long time.

  Further, Patent Document 3 proposes a radiation curable composition that has excellent transparency and mechanical strength, and can give a cured product having an excellent balance between surface hardness and heat and moisture resistance. In Patent Document 3, when the laminate of the cured layer of the radiation curable composition and the resin substrate is stored for a long time under high temperature and high humidity and then returned to room temperature and stored for a long time, the laminate is not deformed. Less reported.

Japanese Patent Laid-Open No. 11-273147 JP 2003-263780 A JP 2006-152289 A

  However, the optical recording medium described in Patent Document 2 has insufficient surface hardness, inferior surface wear resistance, and an object having an uneven shape is pressed against the surface of the cured product, resulting in local stress. When loaded, there is a problem such as poor load resistance, such that the surface thereof is plastically deformed to leave uneven marks (hereinafter sometimes referred to as load marks). On the other hand, when the surface hardness is increased, deformation of the optical recording medium due to environmental changes may increase and warp may occur, and the laminate may be deformed so as to be excellent in both surface hardness and warpage suppression of the optical recording medium. It is necessary to improve the surface hardness while suppressing.

  Furthermore, the present inventors have found that even if the deformation of the optical recording medium or the laminate is small when the temperature is returned from room temperature to room temperature as in the compositions described in Patent Documents 2 and 3, the environmental temperature is low. Warp tends to occur immediately after an abrupt change in environmental humidity, particularly in a low temperature range, or in a relatively low temperature environment such as room temperature or low temperature (for example, 5 ° C.). The problem that it was difficult to suppress was found.

  The present invention has been made in view of the above problems. That is, the object of the present invention is that immediately after the environmental temperature and humidity are changed rapidly, the temperature change occurs particularly in a low temperature region, or in a relatively low temperature environment such as room temperature or low temperature (for example, 5 ° C.). It is an object of the present invention to provide an active energy ray-curable composition that gives a laminate having little warping and sufficient surface hardness and excellent wear resistance and load resistance. In particular, it is an object to provide an active energy ray-curable composition having high recording film protection in an optical recording medium and suitable for forming a protective layer.

  In addition, an object of the present invention is to provide a cured product obtained by curing such a composition, and a laminate suitable for an optical recording medium, in which a cured film made of the cured product is laminated on a substrate. To do.

  As a result of intensive investigations to achieve the above object, the present inventor has cured an active energy ray-curable composition containing a specific structure urethane (meth) acrylate oligomer at a specific ratio into a laminate. In the present invention, the present invention has found that a laminate having little deformation immediately after an abrupt change in environmental temperature and humidity, having sufficient surface hardness, and excellent wear resistance and load resistance is provided. It came.

  That is, the present invention is an active energy ray-curable composition containing a urethane (meth) acrylate oligomer having two or more urethane bonds and two or more (meth) acryloyl groups in one molecule, Contains the following compounds (A) and (B) at a ratio of (A) / (B) = 2.0 to 7.0 (weight ratio), and relates to an active energy ray-curable composition.

  (A) Urethane (meth) acrylate oligomer represented by the following general formula (1)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group or a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, and n represents an integer of 1-50.)
(B) Urethane (meth) acrylate oligomer represented by the following general formula (2)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. And represents an optionally substituted cycloalkylene group having 1 to 15 carbon atoms, and n represents an integer of 1 to 50.)
Further, the present invention is an active energy ray-curable composition further comprising the following compounds (C) and (D), wherein the total content of the compounds (A), (B), (C) and (D) is determined. When it is 100 parts by weight, the total content of the compounds (A), (B), and (C) is 30 to 70 parts by weight, the content of the compound (D) is 70 to 30 parts by weight, and the compound ( It is related with the said active energy ray-curable composition whose content of A) is 5-30 weight part and whose content of a compound (B) is 10 weight part or less.

(C) Urethane (meth) acrylate oligomers other than the above compounds (A) and (B) (D) Monomers having an active energy ray-curable group and / or urethanes (A), (B) and (C) ( Oligomers having active energy ray-curable groups other than (meth) acrylate oligomers In the present invention, the number average molecular weight of the urethane (meth) acrylate oligomer mixture comprising the compounds (A), (B) and (C) is 700 to 4000. It is related with the said active energy ray curable composition which is.

Moreover, this invention relates to the said active energy ray curable composition whose viscosity in 25 degreeC is 500-3000 mPa * s.
The present invention also relates to the active energy ray-curable composition for optical recording media.
The present invention further relates to a cured product obtained by irradiating the active energy ray-curable composition with active energy rays.

  Furthermore, this invention relates also to the laminated body formed by laminating | stacking the cured film which consists of said hardened | cured material on a base material.

  The active energy ray-curable composition of the present invention has a low viscosity and excellent coatability, and when cured to give a cured product, it has excellent transparency, high surface hardness and excellent wear resistance, A cured product having good load resistance can be provided. Furthermore, when a cured film made of the cured product is laminated to form a laminate, the surface hardness is high and the wear resistance is excellent, and deformation due to environmental changes such as temperature and humidity is suppressed, and warpage is small. It can be set as a laminated body. In particular, it is possible to provide a laminate that has a remarkable influence on the warpage of the laminate and that is extremely small in deformation with respect to humidity change in a low temperature environment.

It is a figure which shows the molecular weight distribution of the urethane acrylate oligomer mixture (c) obtained by manufacture example 3 described in the Example. The horizontal axis represents the molecular weight in terms of standard polystyrene, and the vertical axis represents the content.

In the following, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of embodiments of the present invention, and the present invention is not limited to these contents. .
In this specification, (meth) acrylate is a general term for acrylate and methacrylate. The same applies to the (meth) acryloyl group and (meth) acrylic acid.

Further, in the present specification, “to” is used in the sense of including the numerical values described before and after it as a lower limit value and an upper limit value.
1. Active energy ray-curable composition
The active energy ray-curable composition of the present invention includes a urethane (meth) acrylate oligomer having two or more urethane bonds and two or more (meth) acryloyl groups in one molecule, and in particular, the urethane (meth). As the acrylic oligomer, urethane (meth) acrylate oligomers of the following compounds (A) and (B) are contained in a ratio of (A) / (B) = 2.0 to 7.0 (weight ratio).

  (A) Urethane (meth) acrylate oligomer represented by the following general formula (1)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group or a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, and n represents an integer of 1-50.)
(B) Urethane (meth) acrylate oligomer represented by the following general formula (2)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. And represents an optionally substituted cycloalkylene group having 1 to 15 carbon atoms, and n represents an integer of 1 to 50.)
Furthermore, the active energy ray-curable composition of the present invention can contain a urethane (meth) acrylate oligomer other than the compounds (A) and (B) as the compound (C). Hereinafter, the compounds (A), (B) and (C) may be collectively referred to as urethane (meth) acrylate oligomers.

First, the urethane (meth) acrylate oligomer will be described, and then the compounds (A), (B) and (C) will be described in detail.
1-1. Urethane (meth) acrylate oligomer The urethane (meth) acrylate oligomer is not particularly limited as long as it is an oligomer having two or more urethane bonds and two or more (meth) acryloyl groups in one molecule. A urethane acrylate oligomer is preferable in the composition of the present invention because it is excellent in low dose curability when cured by irradiating energy rays, and tack (stickiness) hardly remains. Here, the low dose curable property means that the surface is less tacky and apparently hardened despite the fact that the irradiation dose is about 1/10 of the normal and the curing reaction is hardly progressing. The nature that can be seen.

Examples of urethane (meth) acrylate oligomers include polyisocyanates as raw materials, compounds containing two or more hydroxyl groups, and reactants obtained using (meth) acrylates containing one or more hydroxyl groups. Can be mentioned.
(1) Polyisocyanate Polyisocyanate may be a compound having two or more isocyanate groups in one molecule, for example, a diisocyanate having two isocyanate groups in one molecule or three isocyanate groups. A triisocyanate etc. are mentioned. Among them, a diisocyanate having a C 1-20 alkylene group which may contain an alicyclic structure and a C 1-15 cycloalkylene group which may have a substituent is particularly preferable. Aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate; Xylylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate, naphthalene diiso Aromatic diisocyanates such as cyanate; 1,3,5-triisocyanatecyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatemethyl) -bicyclo [2. 2.1] Heptane, 2- (3-isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo [2.2.1] heptane, 3- (3-isocyanatopropyl) -2,5-di ( Isocyanatomethyl) -bicyclo [2.2.1] heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo [2.2.1] heptane, 6- ( 2-Isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanate propylene ) -Bicyclo [2.2.1] heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo [2.2.1] -heptane, 6- (2 -Triisocyanate such as -isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo [2.2.1] heptane, and multimers thereof. One of these may be used alone, or two or more may be used in combination.

  Of these, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate, bis (isocyanatomethyl) cyclohexane, cyclohexane Alicyclic diisocyanates such as diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate are preferred. Since the surface hardness of the cured product (hereinafter sometimes referred to as cured product) obtained by irradiating the composition with active energy rays is increased, bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) More preferred are alicyclic diisocyanates such as methane and isophorone diisocyanate.

(2) Compound containing two or more hydroxyl groups The compound containing two or more hydroxyl groups only needs to have two or more hydroxyl groups in one molecule. For example, two hydroxyl groups Glycolic alcohol, polyhydric alcohol having 3 or more hydroxyl groups, or polyol having 2 or more hydroxyl groups and having a repeating unit structure in the compound can be used.

  Among them, glycol is preferable because the surface hardness of the cured product is increased, and in particular, an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group, and a carbon number which may have a substituent. Glycols having 2 to 20 cycloalkylene groups are preferred. Specific examples include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,3,5-trimethyl-1,5-pentanediol, 1,6-hexane Diol, 2-ethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, , 12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,2-dimethylolcyclohexane 1,3-dimethylol cyclohexane, alkylene glycols such as 1,4-dimethylol cyclohexane.

Among these, in order to increase the surface hardness of the cured product, glycol having 10 or less carbon atoms between hydroxyl groups is preferable. In order to reduce the viscosity of the composition of the present invention, a glycol having a side chain is preferred.
Specific examples of the polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, 1,2,4-butanetriol, erythritol, sorbitol, pentaerythritol, dipentaerythritol, mannitol, And alkylene polyhydric alcohols containing 3 or more hydroxyl groups.

As the representative polyol, known ones such as polyether polyol, polyester polyol, polycarbonate polyol can be used. Since the polyol is added for the purpose of suppressing warpage of a laminate (hereinafter sometimes referred to as a laminate) formed by laminating a cured film made of a cured product, a polyol having a relatively flexible structure is preferable. Among these, when the composition of the present invention is used as a protective layer of an optical recording medium, a polyester polyol is preferred because the protective layer is in direct contact with the metal-containing layer and the metal-containing layer is unlikely to corrode.

The number average molecular weight of the polyol is preferably 500 or more because the viscosity of the composition of the present invention is easily adjusted to an appropriate range, and is preferably 5000 or less because the surface hardness of the cured product tends to increase.
Specific examples of the polyether polyol include polytetramethylene glycol as a ring-opening polymer of a cyclic ether such as tetrahydrofuran in addition to the glycol multimer, and the glycol, ethylene oxide, propylene oxide, 1, 2 Examples include adducts with alkylene oxides such as -butylene oxide, 1,3-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, and epichlorohydrin.

Specific examples of the polyester polyol include a reaction product of the glycol and a polybasic acid such as maleic acid, fumaric acid, adipic acid, sebacic acid and phthalic acid, and a ring-opening polymer of a cyclic ester such as caprolactone. And polycaprolactone.
Specific examples of the polycarbonate polyol include the glycol and alkylene carbonate such as ethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate; or diphenyl carbonate, 4-methyldiphenyl carbonate, 4-ethyldiphenyl carbonate. 4-propyl diphenyl carbonate, 4,4′-dimethyl diphenyl carbonate, 2-tolyl-4-tolyl carbonate, 4,4′-diethyl diphenyl carbonate, 4,4′-dipropyl diphenyl carbonate, phenyl toluyl carbonate, bischlorophenyl Diaryl carbonates such as carbonate, phenylchlorophenyl carbonate, phenylnaphthyl carbonate, dinaphthyl carbonate; or dimethyl carbonate Reaction with dialkyl carbonates such as dicarbonate, di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, di-t-butyl carbonate, di-n-amyl carbonate, diisoamyl carbonate, etc. Thing etc. are mentioned.

(3) (Meth) acrylate containing one or more hydroxyl groups
The (meth) acrylate containing one or more hydroxyl groups may be any (meth) acrylate having one or more hydroxyl groups and one or more (meth) acryloyl groups in one molecule. From the viewpoint of properties, it is preferably a compound represented by the following general formula (3), preferably a compound in which n in the general formula (3) is an integer of 1 to 30, more preferably hydroxyethyl (meth) acrylate, Hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate. When n in the general formula (3) is small, the surface hardness of the cured product tends to be high, which is preferable.

(R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkylene group having 2 to 6 carbon atoms, and n represents an integer of 1 to 50.)
In addition, addition reaction products of glycidyl ether and (meth) acrylic acid, polyol mono (meth) acrylate, and the like can be used.
As the (meth) acrylate containing one or more hydroxyl groups, one of these may be used alone, or two or more may be used in combination.

The molecular weight of the (meth) acrylate containing one or more hydroxyl groups is preferably 40 or more, more preferably 80 or more, and preferably 800 or less, more preferably 400 or less.
(4) Properties of urethane (meth) acrylate oligomer
As a urethane (meth) acrylate oligomer, it is preferable that it is a highly transparent thing, for example, it is preferable that it is a compound which does not have an aromatic ring. When the urethane (meth) acrylate oligomer has an aromatic ring, the active energy ray-curable composition and its cured product may be colored or may be colored during storage even if it is not initially colored. There is an increase in coloring (so-called yellowing).

  This is considered to be caused by the fact that the double bond part forming the aromatic ring irreversibly changes its structure by the active energy ray. For this reason, the urethane (meth) acrylate oligomer has an aromatic ring. By having a structure that does not have, there is an advantage that the hue is not deteriorated and the light transmittance is not lowered, and it is particularly suitable for application to an application requiring colorless and transparent such as an optical recording medium.

A urethane (meth) acrylate oligomer having no aromatic ring includes a polyisocyanate having no aromatic ring, a compound containing two or more hydroxyl groups having no aromatic ring, and one or more hydroxyl groups having no aromatic ring. It can manufacture by selecting (meth) acrylate containing as a raw material.
Specific examples of the polyisocyanate having no aromatic ring include alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate. Specific examples of the compound containing 2 or more hydroxyl groups that do not include alkylene polyol, alkylene polyester, each polyol of alkylene carbonate, etc., and also contains 1 or more hydroxyl groups that do not have an aromatic ring Specific examples of the (meth) acrylate to be used include hydroxyalkyl (meth) acrylate. In addition, these 1 type may be used independently and may be used in combination of 2 or more type.

The number average molecular weight of the urethane (meth) acrylate oligomer is preferably 700 or more, more preferably 800 or more from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. It is preferable that:
In addition, the weight average molecular weight of the urethane (meth) acrylate oligomer is preferably 1400 or more, more preferably 1500 or more, more preferably 10,000 or less, further from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. Is preferably 4000 or less.

1-1-2. Compound (A)
The compound (A) in the present invention is a urethane (meth) acrylate oligomer represented by the following general formula (1). It is preferable that the composition of the present invention contains the compound (A) because the cured product has a high surface hardness and can be sufficiently cured even when the irradiation amount of active energy rays is low, and is excellent in curability.

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group or a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, and n represents an integer of 1-50.)
The compound (A) is not particularly limited as long as it is represented by the general formula (1), but is usually a reaction product of the diisocyanate, the glycol, and the compound represented by the general formula (3). Is preferred.

R ₁ in the general formula (1) is a hydrogen atom or a methyl group, and is preferably a hydrogen atom because of excellent curability of the composition of the present invention.
R ₂ in the general formula (1) is an alkylene group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 4 carbon atoms.
R ₃ in the general formula (1) is usually a linking group derived from a diisocyanate, a C 1-20 alkylene group which may contain an alicyclic structure, or a carbon which may have a substituent. A cycloalkylene group having a number of 1 to 15. The alkylene group may have a branched structure. Here, the case where R ₃ is a cycloalkylene group refers to a structure in which a nitrogen atom derived from an isocyanate group is directly bonded to an alicyclic structure and does not contain an alkylene group therebetween.

  Preferably, it is derived from a cycloalkylene group having 6 to 15 carbon atoms which may have a substituent derived from cyclohexane diisocyanate or the like, or bis (isocyanatomethyl) cyclohexane, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate, etc. An alkylene group having 6 to 20 carbon atoms which may contain an alicyclic structure, particularly preferably derived from cyclohexane diisocyanate, bis (isocyanatomethyl) cyclohexane, bis (isocyanatocyclohexyl) methane, or isophorone diisocyanate. It is a linking group.

R ₄ in the general formula (1) is usually a linking group derived from glycol, and may have an alicyclic structure, an alkylene group having 2 to 20 carbon atoms, an alkenylene group, or a substituent. It is a good cycloalkylene group having 2 to 20 carbon atoms. The alkylene group and alkenylene group may have a branched structure.
Since the curability of the composition is good and the surface hardness of the resulting cured product is high, it is preferably an alkylene group having 3 to 9 carbon atoms. Specifically, 1,2-propanediol, 1,3 -Propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol 3-methyl-1,5-pentanediol, 2,3,5-trimethyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,6-hexanediol, 2,2,4 -An alkylene group which is a linking group derived from trimethyl-1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, etc. and an alkylene group having a branched structure There it is more preferable.

N in the general formula (1) is an integer of 1 to 50, and preferably 1 to 30 because the surface hardness of the cured product is good.
1-1-3. Compound (B)
The compound (B) in the present invention is a urethane (meth) acrylate oligomer represented by the following general formula (2).

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. And represents an optionally substituted cycloalkylene group having 1 to 15 carbon atoms, and n represents an integer of 1 to 50.)
Although it will not specifically limit if a compound (B) is represented by General formula (2), Usually, it is preferable that it is a reaction material of the compound represented by the said diisocyanate and the said General formula (3).

In the general formula (2), R ₁ , R ₂ , R ₃ , and n are the same as the structure in the general formula (1).
1-1-4. Compound (C)
The compound (C) in the present invention is not particularly limited as long as it is a urethane (meth) acrylate oligomer other than the above compounds (A) and (B). For example, the above-mentioned polyisocyanate, a compound containing two or more hydroxyl groups And urethane (meth) acrylate oligomers other than compounds (A) and (B) among (meth) acrylate reactants containing one or more hydroxyl groups. Specifically, the reaction product of the polyol represented by the diisocyanate, polyether polyol, polyester polyol, polycarbonate polyol, and the compound represented by the general formula (3); the diisocyanate, the glycol, and the general formula (3) And a urethane (meth) acrylate oligomer represented by the following general formula (4).

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group or a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, n is an integer of 1-50, m represents an integer of 2 or more.)
R ₁ , R ₂ , R ₃ , R ₄ and n in the general formula (4) are the same as the structure in the general formula (1).

  The active energy ray-curable composition of the present invention contains the compounds (A) and (B) at a ratio of (A) / (B) = 2.0 to 7.0 (weight ratio). If it is 2.0 or less, the warp tends to increase, and if it is 7.0 or more, the hardness decreases. In order to increase the surface hardness of the cured product and reduce the viscosity of the composition, it is preferably 2.8 or more and preferably 5.0 or less.

  In addition, content of a compound (A) and (B) can be measured by measuring molecular weight distribution of a composition. The molecular weight distribution is measured by size exclusion chromatography, particularly gel permeation chromatography (hereinafter sometimes abbreviated as GPC). Each content is obtained by calculating the peak area ratio of the peak corresponding to the molecular weight of the compound (A) or (B) from the molecular weight distribution measurement result. For example, the molecular weight of the obtained compounds (A) and (B) is calculated from the molecular weight of the raw material when producing the urethane (meth) acrylate oligomer, and the peak corresponding to this is specified.

  In addition, when the active energy ray-curable composition of the present invention contains the compound (C), the urethane (meth) acrylate oligomer is 20% by weight of the total composition as the sum of the compounds (A), (B) and (C). %, More preferably 30% by weight or more, still more preferably 40% by weight or more, and preferably 90% by weight or less, more preferably 80% by weight or less, still more preferably 70% by weight. % By weight or less. When the amount is not less than the lower limit value, both the surface hardness of the cured product and the warpage suppression of the laminate tend to be compatible, and when the value is not more than the upper limit value, the viscosity of the composition tends to become a viscosity suitable for smooth application, which is preferable. .

  In addition, the number average molecular weight of the urethane (meth) acrylate oligomer mixture composed of the compounds (A), (B) and (C) is 700 or more from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. Is preferably 800 or more, and is preferably 4000 or less, more preferably 2000 or less. The weight average molecular weight is preferably 1400 or more, more preferably 1500 or more, and preferably 10,000 or less, more preferably 4000 or less, from the viewpoint of the balance between the viscosity of the composition and the mechanical properties of the cured product. preferable.

1-1-5. Production method of urethane (meth) acrylate oligomer The production method of the urethane (meth) acrylate oligomer used in the present invention is not particularly limited. For example, the polyisocyanate and the compound containing two or more hydroxyl groups, A urethane (meth) acrylate oligomer can be produced by addition reaction with the (meth) acrylate containing one or more hydroxyl groups. Specifically, one molecule of a compound having two or more isocyanate groups in a molecule obtained by addition reaction of a polyisocyanate or a polydiisocyanate and a compound containing two or more hydroxyl groups, and one or more hydroxyls A urethane (meth) acrylate oligomer having a (meth) acryloyl group at both ends can be produced by addition reaction of two (meth) acrylate molecules containing a group.

As the addition reaction catalyst at this time, for example, dibutyltin laurate, dibutyltin dioctoate, dioctyltin dilaurate, and dioctyltin dioctoate are preferable, and one of these may be used alone, You may use combining more than a seed.
This addition reaction is not particularly limited, and can be usually performed by any known method. For example, a mixture of a polyisocyanate, a compound containing two or more hydroxyl groups, a (meth) acrylate containing one hydroxyl group and an addition reaction catalyst is usually 40 ° C. or higher, preferably 50 ° C. or higher. The mixing is usually performed at 90 ° C. or lower, preferably 75 ° C. or lower. As a method of mixing, polyisocyanate, a compound containing two or more hydroxyl groups, a (meth) acrylate containing one hydroxyl group, and an addition reaction catalyst may be mixed and reacted together. First, a polyisocyanate and a compound containing two or more hydroxyl groups are subjected to addition reaction, and then a mixture of (meth) acrylate containing one or more hydroxyl groups and an addition reaction catalyst is added dropwise. The addition reaction can also be performed in stages. In order to reduce the content of the compound (B) and adjust the ratio of the compounds (A) and (B) ((A) / (B)) to a desired range, a method of performing an addition reaction in two stages Is preferred.

When the urethane (meth) acrylate oligomer is produced, it is not necessary to use a solvent in particular, but an organic solvent such as ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene may be used.
In addition, when manufacturing a urethane (meth) acrylate oligomer, unless the effect of this invention is impaired, the polyisocyanate, the compound containing 1 or more hydroxyl groups, and the (meth) acrylate containing 1 or more hydroxyl groups In addition, other components may be included.

  When two or more kinds of urethane (meth) acrylate oligomers are obtained using two or more kinds of compounds, for example, glycol and polyol, as a compound having two or more hydroxyl groups, and the mixture is used, glycol and polyol May be mixed together and reacted with polyisocyanate to obtain a mixture at once, or after reacting glycol and polyol separately with polyisocyanate, the resulting urethane (meth) acrylate oligomer is mixed as a mixture It doesn't matter.

Among them, the compounds (A) and (B) are an alkylene group having 1 to 20 carbon atoms which may include an alicyclic structure, and a cycloalkylene group having 1 to 15 carbon atoms which may have a substituent. Having a diisocyanate (hereinafter sometimes referred to as diisocyanate (I)), an alicyclic structure, an alkylene group having 2 to 20 carbon atoms, an alkenylene group, and optionally having 2 substituents. Reaction of a glycol having -20 cycloalkylene groups (hereinafter sometimes referred to as glycol (II)) and a compound represented by the general formula (3) (hereinafter sometimes referred to as compound (III)) Can be manufactured. Specifically, for example,
After reacting diisocyanate (I) and glycol (II), compound (III) is added and an addition reaction is carried out, thereby being represented by compound (A), compound (B), and general formula (4). Various urethane (meth) acrylate oligomers such as a urethane (meth) acrylate oligomer corresponding to the compound (C) can be obtained.

  Here, compounds (A) and compounds in various urethane (meth) acrylate oligomers obtained by reacting polyisocyanate, a compound having two or more hydroxyl groups and a (meth) acrylate having one or more hydroxyl groups The ratio of (B) is the ratio of the number of isocyanate groups of the polyisocyanate used as a raw material to the number of hydroxyl groups of a compound having two or more hydroxyl groups (hereinafter sometimes referred to as NCO / OH ratio), 2 It can be controlled by the proportion of glycol in compounds having more than one hydroxyl group.

In general, when the ratio of glycol in a compound having two or more hydroxyl groups is high, the content of compound (A) increases when the NCO / OH ratio is large, and the compound increases as the NCO / OH ratio approaches 1. The content of (A) is close to 0%. On the other hand, when the glycol content of the compound having two or more hydroxyl groups is lowered, the content of the compound (A) is lowered.
Further, similarly to the compound (A), when the ratio of the glycol of the compound having two or more hydroxyl groups is high, the content of the compound (B) increases when the NCO / OH ratio is large. As the NCO / OH ratio approaches 1, the content of compound (B) approaches 0%.

  Furthermore, when the ratio of glycol of the compound having two or more hydroxyl groups is high, the ratio of the compound (A) and the compound (B) is large when the NCO / OH ratio is large (A) / (B) (weight ratio). The value of (A) / (B) (weight ratio) tends to increase as the NCO / OH ratio approaches 1. Further, when the glycol content of the compound having two or more hydroxyl groups is lowered, the value of (A) / (B) (weight ratio) tends to increase.

  Therefore, the NCO / OH ratio is preferably in the range of 1.2 to 1.8. When the NCO / OH ratio is greater than 1.2, the molecular weight of the resulting oligomer compound does not become too large, the viscosity of the composition can be easily adjusted to an appropriate range, and many other than the compounds (A) and (B) Since the ratio of the compound containing the urethane bond decreases, the rigidity is appropriate and the warp of the laminate is reduced, which is preferable. When NCO / OH is smaller than 1.8, the ratio of the compound (B) does not increase too much, and the warp when the laminate is formed and the warp when the temperature and humidity change are small, which is preferable.

1-2. Compound (D)
The active energy ray-curable composition of the present invention further includes a monomer having an active energy ray-curable group as the compound (D) and / or urethane (meth) acrylate of the compounds (A), (B), and (C). An oligomer having an active energy ray-curable group other than the oligomer can be included.

The composition of the present invention preferably contains a compound (D) suitable for the purpose of adjusting the viscosity so that it can be easily applied in accordance with various application methods when it is used as a coating film.
The active energy ray-curable group is not particularly limited as long as it is reactive to the active energy ray, and examples thereof include a vinyl group and a (meth) acryloyl group. Among them, a (meth) acryloyl group is preferred from the viewpoint of reactivity. Is preferred.

The monomer having an active energy ray-curable group is not particularly limited as long as it has one or more active energy ray-curable groups, and a vinyl group-containing monomer such as styrene or methylstyrene, (meth) acrylic acid, And (meth) acryloyl group-containing monomers such as esters thereof and (meth) acrylamide.
The oligomer having an active energy ray-curable group is not particularly limited as long as it has one or more active energy ray-curable groups, but one or two (meth) acryloyl groups in one molecule. It is possible to use an oligomer having Examples include epoxy (meth) acrylates, polyester (meth) acrylates, acrylic (meth) acrylates, and unsaturated polyesters.

  Among the above monomers having an active energy ray-curable group or oligomers having an active energy ray-curable group, (meth) acrylate having one or more (meth) acryloyl groups in one molecule (hereinafter referred to as monofunctional (meth)). (Sometimes referred to as an acrylate)) (meth) acrylate having two or more (meth) acryloyl groups in one molecule (hereinafter, sometimes referred to as polyfunctional (meth) acrylate).

  Specific examples of the monofunctional (meth) acrylate include (meth) acrylamides such as N, N-dimethyl (meth) acrylamide; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) ) Hydroxyalkyl (meth) acrylates such as acrylate; (meth) acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylate having a tricyclodecane skeleton, etc. Examples include alicyclic (meth) acrylates; aromatic (meth) acrylates such as phenoxyethyl (meth) acrylate, among which alicyclic (meth) acrylates and aromatic (meth) acrylates are preferred. Properly, among them, tetrahydrofurfuryl (meth) acrylate because it is good curability of the composition, cyclohexyl (meth) acrylate, tricyclodecane having a skeleton (meth) acrylate, phenoxyethyl (meth) acrylate are particularly preferred.

Examples of the polyfunctional (meth) acrylate include aliphatic poly (meth) acrylate, alicyclic poly (meth) acrylate, and aromatic poly (meth) acrylate. Specific examples include polyethylene glycol di (meth) acrylate. 1,2-polypropylene glycol di (meth) acrylate, 1,3-polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, 1,2-polybutylene glycol di (meth) acrylate, polyisobutylene Di (meth) acrylates of alkylene oxide adducts such as ethylene oxide, propylene oxide or butylene oxide of bisphenols such as glycol di (meth) acrylate, bisphenol A, bisphenol F, or bisphenol S Di (meth) acrylates of hydrogenated derivatives of bisphenols such as salts, bisphenol A, bisphenol F or bisphenol S, blocks of various polyether polyol compounds and other compounds, or di (meth) acrylates of random copolymers Di (meth) acrylate having a polyether skeleton such as hexanediol di (meth) acrylate, octanediol di (meth) acrylate, nonanediol di (meth) acrylate, decanediol di (meth) acrylate, 2,2 -Bis [4- (meth) acryloyloxyphenyl] propane, 2,2-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] propane, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] Decane = di (meth) ac Bifunctional (meth) acrylates such as relate, p-bis [β- (meth) acryloyloxyethylthio] xylylene, 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenylsulfone; trimethylolpropane Trifunctional (meth) acrylates such as tris (meth) acrylate, glycerin tris (meth) acrylate, pentaerythritol tris (meth) acrylate; tetrafunctional (meth) acrylates such as pentaerythritol tetrakis (meth) acrylate; dipentaerythritol (Meth) having 5 or more functional groups such as hexa (meth) acrylate.

Of these, bifunctional (meth) acrylates are preferred because of the controllability of the cross-linking formation reaction when irradiated with active energy rays. Among them, as the bifunctional (meth) acrylate, aliphatic di (meth) acrylate and alicyclic di (meth) acrylate are preferable, and hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, bis (Hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = di (meth) acrylate is preferred. Further, from the viewpoint of load resistance as a cured product, a di (meth) acrylate of a diol having 6 to 20 carbon atoms, and further 8 to 12 carbon atoms, specifically, hexanediol di (meth) acrylate, octane. Diol di (meth) acrylate, nonanediol di (meth) acrylate and the like are particularly preferable.

The molecular weight of the compound (D) is preferably 50 or more, more preferably 100 or more, and preferably 1,000 or less, more preferably 500, from the viewpoint of the balance between the viscosity and cure shrinkage of the resulting composition. It is preferable that:
These compounds (D) may be used alone or in combination of two or more. However, it is preferable to contain at least one polyfunctional (meth) acrylate from the point of hardness of the cured product.

  On the other hand, the content of the monofunctional (meth) acrylate when the monofunctional (meth) acrylate is contained in the compound (D) is preferably 70% by weight or less, more preferably 60%. % By weight or less. When the content of the monofunctional (meth) acrylate is 70% by weight or less, the surface of the cured product tends to hardly have a load mark, which is preferable. On the other hand, in order to reduce the content of the monofunctional (meth) acrylate, use a low-viscosity urethane (meth) acrylate oligomer or a polyfunctional (meth) acrylate having a relatively low viscosity. It is preferable to balance the viscosity as the active energy ray-curable composition and various physical properties as the cured product.

1-3. Content ratio of active energy ray-curable compound In the active energy ray-curable composition of the present invention, compounds (A), (B), (C) and (D) (hereinafter collectively referred to as active energy ray-curable compounds) The total content of the compounds (A), (B) and (C) (urethane (meth) acrylate oligomer) is preferably 30 parts by weight. Above, more preferably 40 parts by weight or more, preferably 70 parts by weight or less, more preferably 60 parts by weight or less. When it is 30 parts by weight or more, the strength of the cured product is increased, and when it is 70 parts by weight or less, the viscosity of the composition does not become excessively high and is easily adjusted to an appropriate range.

The content of the compound (D) in the active energy ray-curable composition of the present invention is preferably 30 parts by weight or more, more preferably 40 parts by weight or more with respect to 100 parts by weight of the active energy ray-curable compound, Preferably it is 70 weight part or less, More preferably, it is 60 weight part or less.
The content of the compound (A) is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably 30 parts by weight or less, more preferably 100 parts by weight of the active energy ray-curable compound. Is 20 parts by weight or less. The amount of 5 parts by weight or more is preferable because the surface hardness of the cured product is increased and the curability is excellent. Further, if it is 30 parts by weight or less, it is preferable because the amount of displacement of the warp of the laminate when the humidity changes is small, and this is because the hydrophilicity of the urethane bond is high and the compound (A) has a rigid structure. it is conceivable that.

The content of the compound (B) is preferably 0.1 parts by weight or more and 10 parts by weight or less, and more preferably 5 parts by weight or less with respect to 100 parts by weight of the active energy ray-curable compound. When it is 10 parts by weight or less, it is preferable that warpage when the laminate is used at room temperature (25 ° C., 50% RH) is small, and the amount of warpage displacement when temperature and humidity change is small.

1-4. Polymerization initiator The active energy ray-curable composition of the present invention preferably further contains a polymerization initiator for initiating a polymerization reaction that proceeds by active energy rays (for example, ultraviolet rays, electron beams, etc.). In particular, when the active energy ray is ultraviolet light, it is preferable to contain a polymerization initiator. As the polymerization initiator, a radical generator that is a compound having a property of generating radicals by light is generally used, and any radical generator can be used as long as the effects of the present invention are not significantly impaired. A known radical generator can be used.

  Specific examples of such radical generators include benzophenone, 2,4,6-trimethylbenzophenone, 4,4-bis (diethylamino) benzophenone, 4-phenylbenzophenone, methylorthobenzoylbenzoate, thioxanthone, diethylthioxanthone, and isopropylthioxanthone. Chlorothioxanthone, 2-ethylanthraquinone, t-butylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, Benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, methylbenzoyl formate, 2-methyl-1- [4 (Methylthio) phenyl] -2-morpholinopropan-1-one, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4 , 4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one and the like. Among them, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] 2-methyl-propan-1-one.

  Among the above radical generators, benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-hydroxycyclohexyl are included in that the curing speed is high and the crosslinking density can be sufficiently increased. Phenylketone, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one, and 2,4,6-trimethyl Benzoyldiphenylphosphine oxide is preferred.

  In addition, when the cured product of the active energy ray-curable composition of the present invention is used for an optical recording medium using a laser as a light source, the laser beam necessary for reading sufficiently passes through the cured product layer. It is preferable to select and use the type and amount of the radical generator. In particular, when laser light having a wavelength of 380 to 800 nm is used as a light source, it is particularly preferable to use a short-wavelength photosensitive radical generator in which the obtained cured product layer hardly absorbs laser light.

Among the above radical generators, such short wavelength photosensitive radical generators include benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, methylorthobenzoylbenzoate, diethoxyacetophenone, 2-hydroxy -2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, methyl benzoyl formate, etc. Among them, those having a hydroxyl group such as 1-hydroxycyclohexyl phenyl ketone are particularly preferable.

  In addition, these radical generators may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the radical generator is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, still more preferably 2 parts by weight or more, based on 100 parts by weight of the active energy ray-curable compound. Is 10 parts by weight or less, more preferably 9 parts by weight or less, more preferably 7 parts by weight or less, still more preferably 5 parts by weight or less, and particularly preferably 4 parts by weight or less. When the amount is 0.1 parts by weight or more, the active energy ray-curable composition can be sufficiently cured. On the other hand, when the amount is 10 parts by weight or less, the polymerization reaction proceeds at an appropriate rate, and optical distortion does not occur. , The hue is also favorable.

When a benzophenone polymerization initiator is used, the amount used is preferably 0.5 parts by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight or less. When the amount of the benzophenone-based polymerization initiator is large, the volatile component in the cured product of the active energy ray-curable composition increases, and the film thickness may decrease under a high temperature and high humidity environment.
In addition to these radical generators, for example, known sensitizers such as methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, amyl 4-dimethylaminobenzoate, 4-dimethylaminoacetophenone, etc. A sensitizer may be used in combination. A sensitizer may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the polymerization initiator other than the radical generator include an oxidizing agent, and these polymerization initiators may be used alone or in combination of two or more. The polymerization initiator may contain impurities such as a chlorine atom, a sulfur atom, a phosphorus atom, and a sodium atom, but the content of these impurities is preferably small, and each content is preferably It is 100 ppm or less with respect to a polymerization initiator, More preferably, it is 50 ppm or less, More preferably, it is 30 ppm or less, Most preferably, it is 10 ppm or less.

In addition, when the polymerization reaction is initiated by an electron beam as an active energy ray, the above polymerization initiator can be used, but since it is sufficiently cured without using a polymerization initiator, a radical generator or other polymerization is used. It is preferable not to use an initiator.
1-5. Auxiliary component The active energy ray-curable composition of the present invention may contain an auxiliary component such as an additive, if necessary, as long as the effects of the present invention are not significantly impaired. Specific examples of the auxiliary components include stabilizers such as antioxidants, heat stabilizers, or light absorbers; glass fibers, glass beads, silica, alumina, zinc oxide, titanium oxide, mica, talc, kaolin, metal Fillers such as fibers and metal powders; carbon materials such as carbon fibers, carbon black, graphite, carbon nanotubes, fullerenes such as C60 (fillers and carbon materials may be collectively referred to as inorganic components); Antistatic agents, plasticizers, mold release agents, antifoaming agents, leveling agents, antisettling agents, surfactants, thixotropic agents, modifiers such as epoxy group-containing compounds; pigments, dyes, hue modifiers, etc. Coloring agents; Monomers other than the above-mentioned compounds (A) to (D) or / and oligomers thereof, or curing agents, catalysts, curing accelerators and the like necessary for the synthesis of inorganic components. These auxiliary components may be used alone or in combination of two or more. The content of these auxiliary components is usually 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less of the active energy ray-curable composition.

In these, the silica as a filler which can be used in the active energy ray curable composition of this invention is explained in full detail. Silica here refers to silicon oxide in general, regardless of the ratio of silicon and oxygen, and whether it is crystalline or amorphous. Examples of the silica particles include industrially produced silica particles dispersed in a solvent, or powdered silica particles; silica particles derived and synthesized from raw materials such as alkoxysilanes, and the like. Can be mentioned. Among these, when used in the active energy ray-curable composition of the present invention, it was derived and synthesized from raw materials such as silica particles dispersed in a solvent or alkoxysilane, for ease of mixing and dispersion. Silica particles are preferred.

  The particle diameter of the silica particles is arbitrary, but the number average particle diameter measured by morphological observation using a TEM (transmission electron microscope) is preferably 0.5 nm or more, more preferably 1 nm or more, The thickness 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. The silica particles are preferably ultrafine particles, but if they are 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.

1-6. Production method of active energy ray-curable composition The active energy ray-curable composition of the present invention comprises a compound (A), a urethane (meth) acrylate oligomer of (B), and, optionally, a urethane of compound (C) ( The meth) acrylate oligomer, the compound (D), the polymerization initiator, or the auxiliary component is prepared by stirring and mixing uniformly in a state where the active energy ray is blocked. The order of addition of each compound at that time is not particularly limited, but it is preferable to add a high viscosity liquid component and / or a solid component to a low viscosity liquid component and stir, and the polymerization initiator is Preferably added last.

In addition, the stirring conditions at that time are not particularly limited, and the stirring temperature is usually normal temperature. When heating, the temperature may be usually 90 ° C. or lower, preferably 70 ° C. or lower. .
1-7. Characteristics of Active Energy Ray Curable Composition The active energy ray curable composition of the present invention has a viscosity at 25 ° C. of 300 mPa · s measured by an E type viscometer, a B type viscometer, a vibration type viscometer or the like. It is preferable that it is above, More preferably, it is 500 mPa * s or more. Moreover, it is preferably 3000 mPa · s or less, more preferably 2,500 mPa · s or less, and further preferably 1,500 mPa · s or less. When the viscosity is less than or equal to the upper limit value, for example, it becomes easy to form a cured product having a film thickness of 50 μm or more.

  Methods for adjusting the viscosity of the active energy ray-curable composition include adjusting the molecular weight and addition amount of the urethane (meth) acrylate oligomer and compound (D), and adding a diluent, a solvent, an increase to the composition. Although there exists a method of mixing a viscosity agent, a rheology control agent, etc., especially the method of adjusting each molecular weight or / and content of a urethane (meth) acrylate oligomer and a compound (D) is especially preferable.

  The active energy ray-curable composition of the present invention preferably contains substantially no solvent. This is to prevent bubbles from remaining when the cured film is used, and to prevent troubles in reading and writing information when the optical information recording medium is used. “Contains substantially no solvent” means a state in which the content of so-called organic solvent having volatility or a low boiling point is very low, and the content of the solvent in the active energy ray-curable composition is usually 5% by weight. The content is preferably 3% by weight or less, more preferably 3% by weight or less, still more preferably 1% by weight or less, and particularly preferably 0.1% by weight or less. For simplicity, it means a state in which no odor of the organic solvent is observed.

When the active energy ray-curable composition of the present invention contains water, the water content in the active energy ray-curable composition is preferably 1% by weight or less, more preferably 0.5% by weight or less, and still more preferably. Is 0.1% by weight or less.
2. Cured product The cured product of the present invention is a cured product obtained by irradiating an active energy ray-curable composition with active energy rays.

2-1. Manufacturing method of hardened | cured material The hardened | cured material of this invention is obtained by what is called "active energy ray hardening" which irradiates an active energy ray (electromagnetic wave and an electron beam), and starts a polymerization reaction. There is no restriction | limiting in particular in the form of a polymerization reaction, For example, well-known polymerization forms, such as radical polymerization, anionic polymerization, cationic polymerization, and coordination polymerization, can be used. Of these polymerization modes, radical polymerization is particularly preferable from the viewpoint of the homogeneity of the product and the like due to the initiation of the polymerization reaction proceeding homogeneously and in a short time within the polymerization system.

  Here, the active energy ray is an electromagnetic wave (gamma ray, X-ray, ultraviolet ray, visible ray, infrared ray) that acts on a polymerization initiator that initiates a necessary polymerization reaction to generate a chemical species that initiates the polymerization reaction. , A microwave, etc.), or an electron beam extracted from a particle accelerator of usually 20 to 2000 kV. An example of the active energy ray preferably used in the present invention is preferably an ultraviolet ray, a visible ray, and an electron beam, most preferably an ultraviolet ray, and an electron because an appropriate amount of energy is obtained and a general-purpose light source can be used. Is a line.

  When ultraviolet rays are used as the active energy rays, it is preferable to use as the polymerization initiator a photo radical generator that generates radicals by ultraviolet rays within the aforementioned polymerization initiation. At this time, a sensitizer may be used in combination as necessary. The wavelength of the ultraviolet rays used is preferably 200 nm or more, more preferably 240 nm or more, and preferably 400 nm or less, more preferably 350 nm or less.

The device for irradiating ultraviolet rays is not particularly limited, and known devices such as a xenon lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, and an ultraviolet lamp having a structure for generating ultraviolet rays by a microwave can be used. It can be preferably used.
The integrated light quantity of the active energy ray, preferably 100 mJ / cm ² or more, more preferably 500 mJ / cm ² or higher, preferably 5000 mJ / cm ² or less, more preferably irradiated with 2000 mJ / cm ² or less. If the integrated light quantity is within this range, it can be appropriately selected depending on the composition of the active energy ray-curable composition.

  The irradiation time of the active energy ray is preferably 1 second or longer, more preferably 10 seconds or longer, and preferably 3 hours or shorter, and more preferably 1 hour or shorter in terms of reaction promotion and productivity. When the irradiation energy or irradiation time of the active energy ray is extremely small, the heat resistance and mechanical properties of the cured product may not be sufficiently exhibited due to incomplete polymerization. On the other hand, when it is extremely excessive, deterioration such as deterioration of hue due to light such as yellowing may occur.

  The irradiation with the active energy ray may be performed in one step or may be performed in a plurality of steps. As the radiation source, a diffusion radiation source in which active energy rays spread in all directions is usually used. Irradiation of active energy rays is usually performed by fixing the active energy ray source in a state where the active energy ray curable composition shaped in the mold is fixed or standing, or being conveyed by a conveyor. Do. Further, the active energy ray-curable composition is applied onto a suitable substrate (for example, resin, metal, semiconductor, glass, paper, etc.) to form a coating film, which is irradiated with active energy rays to form the coating film. Can be cured to obtain a cured film.

In addition, when an electron beam is used as the active energy ray, the electron beam irradiation apparatus used for irradiation is not particularly limited, but examples thereof include a curtain type, an area beam type, a broad beam type, and a pulse beam type. The acceleration voltage at the time of irradiation is preferably 10 kV or more, more preferably 100 kV or more, and preferably 1,000 kV or less, more preferably 200 kV or less. Although the light source and irradiation device for electron beam irradiation are expensive, there are advantages that the use of a polymerization initiator can be omitted and that the polymerization is not hindered by oxygen and therefore the surface hardness is good. A cured product having excellent properties, particularly tensile elongation, can be obtained.

2-2. Properties of cured product The cured product of the active energy ray-curable composition of the present invention usually exhibits the property that it does not melt itself and is insoluble in solvents and the like, and even when it is thickened, it is an optical member. It has properties that are advantageous for applications, and has excellent adhesion and surface hardness. Specifically, it exhibits low optical distortion (low birefringence), high light transmittance, mechanical strength, dimensional stability, high adhesion, high surface hardness, and a certain level of heat and humidity resistance, and cures. Shrinkage is small. However, the hardened | cured material of this invention should just obtain a desired characteristic among the above as needed, and does not necessarily need to satisfy | fill all the characteristics.

  The film thickness of the cured product of the present invention can be selected according to the purpose, but when used for applications such as optical recording media, it is preferably 10 μm or more, more preferably 20 μm or more, more preferably It is 30 μm or more, more preferably 70 μm or more, particularly preferably 85 μm or more, preferably 300 μm or less, more preferably 130 μm or less, and even more preferably 115 μm or less. The range described here is preferable because the balance between the influence on the reading and writing of information due to dust and the like and the transmittance is good.

The light transmittance of the cured product of the present invention is a light transmittance per optical path length of 0.1 mm at a wavelength of 550 nm when a cured product having a film thickness of 100 μm obtained by irradiating an active energy ray of 1000 mJ / cm ² as an integrated light amount. The rate is preferably 85% or more, more preferably 89% or more, and the upper limit is not limited. Further, the light transmittance per optical path length of 0.1 mm at a wavelength of 400 nm is preferably 85% or more, more preferably 89% or more, and the upper limit is not limited. When the light transmittance is high, transparency as a cured product is high, and it is preferable that no error occurs when the recorded information is read when used in an optical recording medium. The light transmittance can be measured at room temperature by a known method using, for example, an HP8453 type ultraviolet / visible absorptiometer manufactured by Hewlett-Packard Company.

  In order to set the light transmittance of the cured product of the present invention within the above range, it is preferable to use a component having a high light transmittance as each component constituting the active energy ray-curable composition. Furthermore, those having a small amount of impurities such as colored substances and decomposed substances in each component are preferred. Moreover, the thing with little catalyst amount at the time of manufacture is preferable. These are particularly effective for not reducing the light transmittance in the visible light region. Furthermore, it is preferable to select an aliphatic or alicyclic skeleton having no aromatic ring in each component. These are particularly effective for preventing the light transmittance in the ultraviolet region from being lowered.

Further, the cured product of the present invention preferably has a tensile elastic modulus at 25 ° C. of 500 MPa or more as a cured product having a film thickness of 100 μm obtained by irradiating an active energy ray of 1000 mJ / cm ² as an integrated light amount. The pressure is more preferably 1,000 MPa or more, more preferably 4,000 MPa or less, and still more preferably 3,000 MPa or less. When the tensile elastic modulus is 500 MPa or more, load resistance tends to be good. On the other hand, when the tensile elastic modulus is 4,000 MPa or less, deformation hardly occurs, warpage is small when a laminate is formed, and delamination between layers occurs. This is preferable because it tends to be less likely to occur.

The surface hardness of the cured product of the present invention is a surface hardness according to a pencil hardness test in accordance with JIS K5600-5-4, preferably 6B or more, more preferably 4B or more, and still more preferably B.
Above, particularly preferably HB or more.
Furthermore, the surface hardness of the hard coat layer when a general hard coat agent is laminated on the cured product of the present invention is preferably B or more, more preferably HB or more, and still more preferably H or more. Since the cured product of the present invention has a high surface hardness, it is effective to laminate a general hard coating agent because it has a particularly high surface height.

3. Laminated body The laminated body of this invention is a laminated body formed by laminating | stacking the cured film which consists of hardened | cured material of this invention on a base material.
Normally, a laminate with multiple layers made of different materials has different effects when subjected to an environment such as temperature and humidity in each layer. Warping occurs. In the laminated body of this invention, the deformation | transformation of such a laminated body can be suppressed and the curvature of the laminated body accompanying an environmental change can be made small.

Although it does not specifically limit as a base material of the laminated body of this invention unless the effect of this invention is impaired, A plastic base material or a transparent base material is mentioned.
Examples of the plastic substrate include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polymethyl methacrylate (PMMA), or methyl methacrylate (MMA) copolymer (for example, methyl methacrylate-styrene copolymer resin ( MS resin)), polycarbonate, special polycarbonate (for example, Teijin Pure Ace), triacetyl cellulose, acrylonitrile butadiene styrene copolymer resin (ABS resin), modified polyolefin resin, hydrogenated polystyrene resin, cycloolefin-based transparent resin (for example, ASR made by JSR, ZEONOR made by Nippon Zeon, etc.). Alternatively, as other examples of the transparent substrate, thermosetting or photocurable transparent resins (for example, transparent epoxy resins, transparent urethane resins, thermosetting acrylic resins, photocurable acrylic resins, thermosetting) Other cured organic / inorganic hybrid resins and cured products such as various photocurable organic / inorganic hybrid resins).

These base materials may be in the form of molded articles (articles), or may be formed into desired articles after being formed into a laminate. Moreover, you may interpose another layer between a base material and an application surface.
The method for forming the cured film made of the cured product of the present invention is not particularly limited, and the cured film made of the composition of the present invention may be formed and then bonded to the base material. A method may be used in which a coating film is formed by applying to a material and cured to form a cured film.

Preferred examples of the coating method include spin coating, dip coating, flow coating, spray coating, bar coating, gravure coating, roll coating, blade coating, and air knife coating.
After a coating film is formed on the substrate by the above coating method, a volatile component is removed by heating and drying, and then irradiation with active energy rays yields a cured film.

The type of active energy ray and the irradiation method are the same as those in the above-described method for producing a cured product. A cured film cured with such active energy rays is particularly preferable because of its excellent balance between productivity and physical properties.
4). Optical Recording Medium The active energy ray-curable composition and the cured product and laminate of the present invention are suitably used as a material for an optical recording medium described below, particularly as a material for forming a protective layer of an information recording layer. .

Currently, optical recording media generally used include read-only media (ROM media), write-once media that can be recorded only once (WriteOnce media), and rewritable media that can repeatedly perform recording and erasure. The active energy ray-curable composition for an optical recording medium and the active energy ray-cured product of the present invention can be applied to any of these media (Rewriteable media).

  These optical recording media employ a layer structure according to their intended use. For example, in a read-only medium, a single layer containing a metal such as aluminum, silver, gold or the like is usually formed on a substrate on which unevenness for reproduction is formed. Further, in a write-once medium, a recording / reproducing functional layer in which a reflective layer containing a metal such as aluminum, silver or gold and a recording layer containing an organic dye are usually laminated on a substrate in this order. Is formed. In a rewritable medium, a reflective layer containing a metal such as aluminum, silver or gold, a dielectric layer, a recording layer containing an organic dye, and a dielectric layer are usually formed on a substrate. Are formed in this order. The active energy ray-curable composition of the present invention and the cured product thereof are a single layer in a read-only medium, a recording / reproducing functional layer in a write-once medium, and a recording / reproducing functional layer in a rewritable medium. It is suitable for use as a protective layer formed thereon.

  On the other hand, the wavelength of the laser light as the recording / reproducing light for recording / reproducing of the optical recording medium uses light of the optimum wavelength according to the standard such as CD, DVD, Blu-ray disc, HDDVD and the like. In addition, with the recent popularization of rich contents, the demand for higher density and higher capacity of optical recording media is increasing, and research using a blue laser with a shorter wavelength has been actively conducted. This next-generation high-density optical recording medium using a blue laser is an optical recording in which a recording / reproducing functional layer including a dielectric layer, a recording layer, a reflective layer, etc. is formed on a substrate, and a protective layer is formed thereon. Recording / reproducing light having a wavelength of usually 350 nm or more, preferably 380 nm or more, and usually 450 nm or less, preferably 430 nm or less, which is a medium. The active energy ray-curable composition of the present invention and the cured product thereof can be particularly suitably used for this next-generation high-density optical recording medium.

  The active energy ray-curable composition of the present invention and the laminate or optical recording medium in which the cured product is used have, for example, a two-layer structure having two recording layers and two reflective layers. It may be a thing. In the case of this two-layer type, one layer may be laminated on the substrate in order, or two layers obtained by laminating a pair of a recording layer and a reflective layer may be bonded together. Good. Further, a three-layer structure may be adopted, and the bonding may be performed through an adhesive layer. Furthermore, if necessary, a hub may be attached and incorporated in the cartridge.

  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, particularly preferably 85 μm or more, and usually 300 μm or less, preferably 130 μm or less, more preferably 115 μm. It is as follows. If the film thickness is in such a range, the influence of dust and scratches attached to the surface of the protective layer can be reduced, and the thickness of the recording / reproducing functional layer is sufficient to protect the moisture from outside air and the like. be able to. Moreover, a uniform film thickness can be easily formed by a general coating method used in spin coating or the like.

Specific examples of the present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited by these examples unless it exceeds the gist.
<Evaluation method>
[Method of measuring molecular weight and content of compounds (A) and (B)]
Gel permeation chromatography (HLC-8120GPC manufactured by Tosoh Corporation), column (TskGEL SuperH 1000, 2000, 3000), detector RI
(Refractive index), eluent Tetrahydrofuran (THF), flow rate 0.5 ml / min was used to measure the molecular weight distribution, and from the molecular weight distribution measured in terms of standard polystyrene, it corresponds to the molecular weight of compound (A) or (B) The peak to be determined was determined, and the peak area ratio of those peaks was calculated and used as the content.

The sample for measurement was adjusted to be a THF solution having a composition solution of 0.2% by weight.
[viscosity]
According to JIS K5600-2-3, the viscosity at 25 ° C. was measured with an E-type viscometer.
[Low irradiation curability]
An active energy ray-curable composition is formed to have a thickness of 100 ± 10 μm on a substrate in which an Ag reflection layer having a thickness of 100 nm is formed on the surface of a circular polycarbonate plate having a thickness of 1.1 mm and a diameter of 120 mm by sputtering. Thus, after applying by spin coating, under a condition of oxygen concentration of 20%, using a high-pressure mercury lamp having an irradiance of 400 mW / cm ² at a wavelength of 245 nm, the ultraviolet light becomes an integrated light amount of 74 mJ / cm ² . The surface state after irradiation with a UV irradiation apparatus (JU-C1500, manufactured by JATEC) was evaluated as follows.
×: The surface is sticky and the curing is insufficient Δ: Cured but remains sticky on the surface ○: The curing is sufficient and the surface is not sticky [Pencil hardness]
According to JIS K5600-5-4, the pencil hardness on the surface of the laminate was measured. In addition, although the pencil hardness of the hard-coat layer surface of a laminated body was measured here, these values are values reflecting the surface hardness of the cured film which consists of hardened | cured material of this invention.

[Initial tilt]
The laminate was allowed to stand at 25 ° C. and 50% RH for 24 hours, and then the tilt was measured using a displacement sensor LT-9010 (manufactured by KEYENCE).
Tilt expresses the warpage from the flat surface on the outermost periphery by an angle, and is a value indicating the warpage of the laminate. Each numerical value of the initial tilt represents the warpage of the substrate alone and the amount of warpage displacement when the laminate is formed.

The upward warping when the protective layer of the laminate was down was positive, and the downward warping was negative. The substrate used was originally warped by plus 0.3 °.
[Low temperature tilt]
The laminate after measuring the initial tilt was measured for 24 hours at 5 ° C. and 45% RH. Each numerical value of the low-temperature tilt represents an amount of change from the warp of the laminate in which the initial tilt is measured. It is preferable that the absolute value of the low temperature tilt is small because deformation of the laminated body due to temperature change is small.

[Humidity tilt]
After the laminated body whose initial tilt was measured was placed at 25 ° C. and 90% RH for 24 hours, the tilt immediately after placing it at 25 ° C. and 50% (0 hour) was measured, and then 1, 2, 3, 5, 9 The change in tilt over time was measured. The amount of change over time when the absolute value of the amount of change from the tilt at the time of 0 hour was the maximum was taken as the humidity tilt. It is preferable that the humidity tilt has a smaller absolute value because there is less deformation of the laminate due to a sudden change in humidity.

<Production Example 1> Synthesis of urethane acrylate oligomer mixture (a) 222 g of isophorone diisocyanate was placed in a four-necked flask, heated to 70 to 80 ° C in an oil bath, and gently stirred until the temperature became constant. When the temperature became constant, 79 g of 1,6-hexanediol was added dropwise using a dropping funnel, and the mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature is lowered to 70 ° C., a mixture of 81 g of hydroxyethyl acrylate and 0.1 g of p-methoxyhydroquinone is dropped with a dropping funnel, and when the dropping is finished, the temperature is kept at 80 ° C. and stirred for 10 hours to obtain a urethane acrylate oligomer. Mixture (a) was synthesized. Next, 164 g of tetrahydrofurfuryl acrylate (THFA, manufactured by Osaka Organic Chemical Co., Ltd.) is added as a compound (D) and diluted so that the urethane acrylate oligomer mixture (a) becomes 70% by weight, and the urethane acrylate oligomer mixture (a) is contained. A composition solution was prepared.

At this time, the ratio of the isocyanate group of isophorone diisocyanate to the hydroxyl group of 1,6-hexanediol (NCO / OH ratio) is 1.5.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (a) in a composition liquid was measured by GPC, the number average molecular weight was 1300 and the weight average molecular weight was 2060. Moreover, content of the compound (A) in the obtained composition liquid is 15.0 weight%, content of a compound (B) is 5.0 weight%, (A) / (B) = 3.0 (weight) Ratio).

<Production Example 2> Synthesis of urethane acrylate oligomer mixture (b) A urethane acrylate oligomer mixture (b) was prepared in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 107 g of 1,9-nonanediol. Synthesized. Next, 176 g of THFA was added as the compound (D) and diluted such that the urethane acrylate oligomer mixture (b) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (b).

At this time, the NCO / OH ratio is 1.5.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (b) in a composition liquid was measured by GPC, the number average molecular weight was 1490 and the weight average molecular weight was 2360. Further, the content of the compound (A) in the obtained composition liquid is 17.1% by weight, the content of the compound (B) is 3.4% by weight, and (A) / (B) = 5.0 (weight) Ratio).

<Production Example 3> Synthesis of urethane acrylate oligomer mixture (c) A urethane acrylate oligomer mixture was prepared in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 79 g of 3-methyl-1,5-pentanediol. (C) was synthesized. Next, 164 g of THFA was added as the compound (D) and diluted so that the urethane acrylate oligomer mixture (c) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (c).

At this time, the NCO / OH ratio is 1.5.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (c) in a composition liquid was measured by GPC, the number average molecular weight was 1240 and the weight average molecular weight was 1970. Further, the content of the compound (A) in the obtained composition liquid was 14.1% by weight, the content of the compound (B) was 5.8% by weight, and (A) / (B) = 2.4 (weight) Ratio).

<Production Example 4> Synthesis of urethane acrylate oligomer mixture (d) Production Example except that 79 g of 1,6-hexanediol was changed to 89 g of 3-methyl-1,5-pentanediol and 81 g of hydroxyethyl acrylate was changed to 61 g. In the same manner as in 1, a urethane acrylate oligomer mixture (d) was synthesized. Next, 159 g of THFA was added as the compound (D) and diluted so that the urethane acrylate oligomer mixture (d) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (d).

At this time, the NCO / OH ratio is 1.3.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (d) in a composition liquid was measured by GPC, the number average molecular weight was 1690 and the weight average molecular weight was 2820. Further, the content of the compound (A) in the obtained composition liquid is 8.5% by weight, the content of the compound (B) is 2.8% by weight, and (A) / (B) = 3.0 (weight) Ratio).

<Production Example 5> Synthesis of urethane acrylate oligomer mixture (e) Urethane acrylate oligomer mixture in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 70 g and 81 g of hydroxyethyl acrylate was changed to 100 g. (E) was synthesized. Next, 168 g of THFA was added as the compound (D), and the urethane acrylate oligomer mixture (e) was diluted to 70 wt% to prepare a composition liquid containing the urethane acrylate oligomer mixture (e).

At this time, the NCO / OH ratio is 1.7.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (e) in a composition liquid was measured by GPC, the number average molecular weight was 1050 and the weight average molecular weight was 1550. Further, the content of the compound (A) in the obtained composition liquid is 20.5% by weight, the content of the compound (B) is 8.4% by weight, and (A) / (B) = 2.4 (weight) Ratio).

<Comparative Production Example 1> Synthesis of urethane acrylate oligomer mixture (f) Urethane acrylate oligomer in the same manner as in Production Example 1 except that 79 g of 1,6-hexanediol was changed to 59 g and 81 g of hydroxyethyl acrylate was changed to 122 g. Mixture (f) was synthesized. Next, 173 g of THFA was added as the compound (D) and diluted such that the urethane acrylate oligomer mixture (f) was 70% by weight to prepare a composition liquid containing the urethane acrylate oligomer mixture (f).

At this time, the NCO / OH ratio is 2.0.
Moreover, when the molecular weight of the urethane acrylate oligomer mixture (f) in a composition liquid was measured by GPC, the number average molecular weight was 840 and the weight average molecular weight was 1180. Further, the content of the compound (A) in the obtained composition liquid is 25.0% by weight, the content of the compound (B) is 14.4% by weight, and (A) / (B) = 1.7 (weight) Ratio).

<Example 1>
In a 200 cc flask, 70 g of the urethane acrylate oligomer mixture prepared above (composition liquid containing (a), 20 g of THFA, 10 g of 1,9-nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), α-hydroxycyclohexyl-phenyl ketone 3 g was weighed and mixed at room temperature using a stirring blade for 5 hours to obtain a uniform liquid active energy ray-curable composition.The composition of the obtained active energy ray-curable composition is shown in Table 2. It was.

Moreover, the viscosity of the obtained composition was 1000 m · Pa, and the low dose curability was evaluated. The results are shown in Table 3.
Next, the active energy ray-curable composition is coated on a substrate having a thickness of 1.1 mm and a diameter of 120 mm on a circular polycarbonate plate surface on which a 100 nm thick Ag reflective layer is formed by sputtering. After applying by spin coating so as to be 100 ± 10 μm, UV light is accumulated at 500 mJ / cm ² using a high-pressure mercury lamp with an irradiance of 400 mW / cm ² at a wavelength of 245 nm under the condition of an oxygen concentration of 20%. Then, a protective layer was formed by irradiation with a UV irradiation apparatus (JU-C1500, manufactured by JATEC). Further, a hard coat layer composition having the following composition was applied thereon as a hard coat layer by spin coating so that the thickness of the coating film was 4 ± 1 μm, and ultraviolet rays were applied at 1000 mJ / cm under the same conditions as described above. Irradiated so as to obtain an integrated light quantity of ² , and a cured laminate was created.

The obtained laminate was evaluated for pencil hardness, initial tilt, low temperature tilt and humidity tilt. The results are shown in Table 3.
<< Hard Coat Layer Composition >>
90 g of dipentaerythritol (hexa / penta) acrylate (“Kayarad DPHA” manufactured by Nippon Kayaku Co., Ltd.), methyl methacrylate, perfluorooctylethyl methacrylate, and mercapto groups at both ends as water / oil repellency / low friction agents Of polydimethylsiloxane (“X-22-167B” manufactured by Shin-Etsu Chemical Co., Ltd.) and glycidyl methacrylate copolymer (25/40/5/30 (weight ratio)) (35% propylene glycol monomethyl ether) Solution) 28.57 g and 1 g of 1-hydroxycyclohexyl phenyl ketone (“Irgacure-184” manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator in an amount of 40 wt% solid content of propylene glycol monomethyl ether acetate Only for 2 hours at room temperature in the dark They were prepared by.

<Examples 2 to 5, Comparative Example 1>
In the same manner as in Example 1, an active energy ray-curable composition was prepared so as to have the composition shown in Table 2. The viscosity and low dose curability of each composition are shown in Table 3.
A laminate was obtained in the same manner as in Example 1 except that the active energy ray-curable composition obtained in each example was used, and pencil hardness, initial tilt, low temperature tilt and humidity tilt were evaluated. It was shown to.

When the active energy ray-curable composition of the present invention is cured to form a laminate, there is little deformation immediately after the environmental temperature and environmental humidity change abruptly, it has sufficient surface hardness, and is resistant to abrasion. A laminated body excellent in wear and load resistance can be provided. In particular, it is an active energy ray-curable composition suitable for obtaining a protective layer having high recording film protection in an optical recording medium.
As a result, the laminate obtained by laminating the cured product obtained from the active energy ray-curable composition of the present invention can read and write information stably even when the environment such as temperature and humidity changes. The present invention can be effectively applied to optical recording media such as the beginning.

Claims (7)

An active energy ray-curable composition containing a urethane (meth) acrylate oligomer having two or more urethane bonds and two or more (meth) acryloyl groups in one molecule, the composition comprising the following compound (A ) And (B) at a ratio of (A) / (B) = 2.0 to 7.0 (weight ratio), an active energy ray-curable composition.
(A) Urethane (meth) acrylate oligomer represented by the following general formula (1)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. A cycloalkylene group having 1 to 15 carbon atoms which may be present, R ₄ is an alkylene group having 2 to 20 carbon atoms which may contain an alicyclic structure, an alkenylene group or a carbon number which may have a substituent. 2-20 cycloalkylene groups are represented, and n represents an integer of 1-50.)
(B) Urethane (meth) acrylate oligomer represented by the following general formula (2)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 6 carbon atoms, R ₃ is an alkylene group having 1 to 20 carbon atoms which may contain an alicyclic structure, and a substituent. And represents an optionally substituted cycloalkylene group having 1 to 15 carbon atoms, and n represents an integer of 1 to 50.) Furthermore, it is an active energy ray-curable composition containing the following compounds (C) and (D), and the total content of the compounds (A), (B), (C) and (D) is 100 parts by weight. When the total content of the compounds (A), (B), and (C) is 30 to 70 parts by weight, the content of the compound (D) is 70 to 30 parts by weight, and the content of the compound (A) The active energy ray-curable composition according to claim 1, wherein 5 to 30 parts by weight and the content of the compound (B) is 10 parts by weight or less.
(C) Urethane (meth) acrylate oligomer other than the above compounds (A) and (B) (D) Monomer having an active energy ray-curable group and / or urethane (A), (B) and (C) ( Oligomers having active energy ray-curable groups other than (meth) acrylate oligomers The active energy ray curable composition of Claim 2 whose number average molecular weights of the urethane (meth) acrylate oligomer mixture which consists of said compound (A), (B) and (C) are 700-4000.   The active energy ray curable composition in any one of Claims 1-3 whose viscosity in 25 degreeC is 300-3000 mPa * s.   The active energy ray-curable composition according to any one of claims 1 to 4, which is used for an optical recording medium.   Hardened | cured material obtained by irradiating an active energy ray curable composition in any one of Claims 1-5 with an active energy ray.   The laminated body formed by laminating | stacking the cured film which consists of hardened | cured material of Claim 6 on a base material.

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