JP2010065192A - Radiation curable composition and cured product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation curable composition capable of realizing a laminate having a low viscosity, excellent transparency and little deformation with respect to environmental temperature and humidity change, and a cured product thereof.
A radiation curable composition having a viscosity at 25 ° C. of 100 to 5000 mPa · s, a light transmittance of 85% or more at a wavelength of 400 nm of a cured product having a thickness of 0.1 mm, and at least one kind. A compound having a polyester skeleton having a molecular weight of 500 or more and di (meth) acrylate which is a (meth) acrylate of two hydroxyl groups linked by 7 or less carbon-carbon bond chains, The content ratio of the total polyether skeleton and the content of the total polycarbonate skeleton contained in the radiation curable composition with respect to the total polyol skeleton contained in the adhesive composition are both 20% by weight or less. A radiation curable composition and a radiation curable product obtained by curing the radiation curable composition by irradiation with radiation.
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Description

  The present invention relates to a radiation curable composition, a cured product thereof, and an optical recording medium using the same. More specifically, the present invention relates to a radiation curable composition that has a low viscosity, excellent transparency, and can give a cured product with little deformation against changes in environmental temperature and humidity, and the cured product.

Radiation curable materials are widely used in the so-called optoelectronic field represented by lenses and optical fibers. This means that unlike thermoplastic resins and thermosetting resins, radiation curable materials do not need to be heated when forming and processing, and that they can be formed and processed in a short time by irradiation. Because you can.
On the other hand, in recent years, the volume of information data handled in the fields of computers, movies, television images, etc. has increased remarkably, and technologies related to recording media for recording the information data have been rapidly advanced. The importance of optical recording media represented by CD, DVD, BD (Blu-ray Disc (registered trademark)) and the like is increasing for reasons such as being advantageous in terms of security.

Many attempts have been made to use a radiation-curable composition for a protective layer for protecting an information data recording layer in such an optical recording medium.
For example, Patent Document 1 discloses that a monomer having a urethane bond or / and an oligomer thereof includes at least a compound having two or more isocyanate groups in a molecule, a polymer polyol, and a (meth) acrylate having a hydroxyl group. A radiation curable composition comprising two or more skeletons selected from the group consisting of a polyether polyol skeleton, a polyester polyol skeleton, and a polycarbonate polyol skeleton, wherein the polymer polyol is obtained by reaction. However, it is described that it has excellent transparency and surface hardness as a cured product and can suppress the occurrence of warping after the laminate is placed in a certain high temperature and high humidity environment.

However, this radiation curable composition is highly warped against more severe changes in environmental humidity. For example, it is still insufficient when used as a protective layer for an information recording layer in an optical recording medium. Has come to understand.
JP 2006-152289 A

  The present invention has been made to realize a reduction in warpage with respect to a change in environmental humidity in the above-described prior art. Therefore, the present invention can realize a laminated body with less deformation with respect to a change in environmental temperature and humidity. An object of the present invention is to provide a radiation curable composition and a cured product thereof.

As a result of intensive studies to give a solution to the above-mentioned problems, the present inventors,
1) A compound having a molecular weight of 500 or more derived from a polyol, wherein the polyol contains at least one polyester polyol, and the content of all polyether skeletons and the content of all polycarbonate skeletons with respect to all polyol skeletons. A range of compounds,
2) The inventors have found that the object can be achieved by using a radiation curable composition containing di (meth) acrylate, and have completed the present invention.

That is, the first gist of the present invention is a radiation curable composition having a viscosity of 100 to 5000 mPa · s at 25 ° C. and a light transmittance of 85% or more at a wavelength of 400 nm of a cured product having a thickness of 0.1 mm. There,
1) A compound derived from a polyol and having a molecular weight of 500 or more, wherein the polyol contains at least one polyester polyol, and the content of all polyether skeletons and the content of all polycarbonate skeletons with respect to all polyol skeletons. A compound that is 20% by weight or less,
2) It exists in the radiation-curable composition characterized by containing di (meth) acrylate.
Here, 1) The compound derived from polyol and having a molecular weight of 500 or more is preferably (meth) acrylate.

Here, the di (meth) acrylate is connected by 7 or less carbon-carbon bond chains.
Preferably, it is a (meth) acrylic acid ester of a single hydroxyl group.
The di (meth) acrylate may be butanediol di (meth) acrylate, pentanediol di (meth) acrylate, methylpentanediol di (meth) acrylate, hexanediol di (meth) acrylate and bis (hydroxymethyl) tricyclo [ 5.2.1.0 ^2,6 ] Decane = di (meth) acrylate is preferably at least one di (meth) acrylate selected from the group consisting of.

Further, the polyester polyol preferably contains a polyester polyol having a molecular weight of 800 or more.
The compound derived from the polyol and having a molecular weight of 500 or more is preferably urethane (meth) acrylate.
Moreover, it is preferable to contain the compound which has an isocyanurate skeleton, and it is preferable that the compound which has the said isocyanurate skeleton is a urethane (meth) acrylate.
The second gist of the present invention resides in a cured product of the above-mentioned radiation curable composition.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation-curable composition which can implement | achieve the laminated body which is low-viscosity, excellent in transparency, and with few deformation | transformation with respect to environmental temperature / humidity change, and its hardened | cured material can be provided. Therefore, its industrial value is extremely high.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention. it can. In the present invention, the molecular weight means a number average molecular weight unless otherwise specified.
1. Radiation curable composition
The radiation curable composition of the present invention comprises:
A radiation curable composition having a viscosity of 100 to 5000 mPa · s and a light transmittance of 85% or more at a wavelength of 400 nm of a cured product having a thickness of 0.1 mm,
1) A compound derived from a polyol and having a molecular weight of 500 or more, wherein the polyol contains at least one polyester polyol, and the content of all polyether skeletons and the content of all polycarbonate skeletons with respect to all polyol skeletons. A compound that is 20% by weight or less,
2) It contains di (meth) acrylate.

Hereinafter, the components contained in the radiation curable composition of the present invention will be described in detail.
1-1. Component 1)
As the component 1) of the radiation-curable composition of the present invention, “a compound having a molecular weight of 500 or more derived from a polyol, the polyol containing at least one polyester polyol, A compound having a polyether skeleton content and a total polycarbonate skeleton content of 20% by weight or less is used.

As the component 1) of the radiation curable composition of the present invention, a polyether skeleton and a polycarbonate skeleton may be contained, but the content of the polyether skeleton and the polycarbonate skeleton with respect to the total polyol skeleton is any Must be 20% by weight or less.
The polyether skeleton in the present invention means a skeleton having a polyether repeating structure represented by the following general formula (1) and having both ends sandwiched between oxygen atoms and having a molecular weight of 200 or more.

In the following general formula (1), R is an alkylene group which may contain an aromatic ring or an alicyclic ring, and may be branched. A main example is a skeleton portion sandwiched between terminal oxygen atoms excluding both hydrogen atoms at both ends of the polyether polyol.
The polycarbonate skeleton in the present invention means a skeleton having a polycarbonate repeating structure represented by the following general formula (2) and having both ends sandwiched between oxygen atoms and having a molecular weight of 200 or more.

  In the following general formula (2), R is an alkylene group which may contain an oxygen atom, an ester bond, an aromatic ring or an alicyclic ring, and may be branched. A main example is a skeleton part sandwiched between terminal oxygen atoms excluding hydrogen atoms at both terminals of polycarbonate polyol.

  When the total polyether skeleton exceeds 20 wt% with respect to the total polyol skeleton, the warpage deformation of the laminate with respect to environmental humidity changes tends to increase due to an increase in the dehydration shrinkage rate.

Further, if the total polycarbonate skeleton contains more than 20% by weight with respect to the total polyol skeleton, the elastic modulus at the time of water absorption is large, so that the warpage deformation of the laminate with respect to environmental humidity changes tends to increase.
The component 1) contained in the radiation curable composition of the present invention is a compound having a molecular weight of 500 or more derived from a polyol, and the polyol contains at least one polyester polyol.

In the present invention, a skeleton having a polyester repeating structure in which both ends are sandwiched between oxygen atoms and represented by the following general formula (3) and having a molecular weight of 200 or more is represented as a polyester skeleton.
In the following general formula (3), R1 and R2 are the same or different alkylene groups (however, they may contain an oxygen atom, an ester bond, an aromatic ring, an alicyclic ring, or may be branched). A main example is a skeleton part sandwiched between terminal oxygen atoms excluding hydrogen atoms at both terminals of the polyester polyol.

Component 1) contained in the radiation curable composition of the present invention is a compound having the polyester skeleton.
Component 1) is preferably liquid and colorless and transparent, and preferably has a functional group having radiation curability from the viewpoint of physical properties and storage stability of the cured product. Examples of such a functional group include a (meth) acryloyl group, a vinyl group, a mercapto group, and an epoxy group, and a (meth) acryloyl group that can easily obtain a sufficient curing rate in air is particularly preferable.

The polyester skeleton has a feature that the surface modulus is high, but the elastic modulus is low and the warp is less likely to occur. Further, it is preferable because the degree of expansion and contraction with respect to a change in humidity tends to be small as compared with other skeletons.
Here, the compound having a polyester skeleton and having a molecular weight of 500 or more is preferably a reactive product obtained by reacting a composition containing a polyester polyol having a molecular weight of 800 or more.

Furthermore, what is called urethane (meth) acrylate which has a urethane bond from the point with the favorable mechanical physical property of hardened | cured material and the adhesiveness to a base material is used suitably.
Hereinafter, component 1) is a compound having a molecular weight of 500 or more derived from polyol, the polyol containing at least one polyester polyol, and the content of all polyether skeletons and the total content of all polyether skeletons. The case where urethane (meth) acrylate is used as the compound having a polycarbonate skeleton content of 20% by weight or less will be described in detail.

Urethane (meth) acrylate is usually obtained by reacting a polyisocyanate and a hydroxyl group-containing compound with a hydroxyl group-containing (meth) acrylate. As urethane (meth) acrylate in this invention, urethane acrylate is preferable from the point which is excellent in surface curability. Further, it is necessary to use a polyester polyol as at least a part of the compound containing a hydroxyl group.
(A) Polyisocyanate
Polyisocyanate is a compound having two or more isocyanate groups in the molecule. For example, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate, bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate. , Cycloaliphatic diisocyanates such as bis (isocyanatocyclohexyl) methane and isophorone diisocyanate, aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate and naphthalene diisocyanate, and multimers thereof. One of these may be used alone, or two or more may be used in combination. . Among these, alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate are preferable in that the hue of the urethane (meth) acrylate obtained is good. preferable.

In addition, ethylene diisocyanate trimer or / and pentamer, hexamethylene diisocyanate trimer or / and pentamer in terms of good surface hardness as a cured product of the radiation curable composition of the present invention. And trimers or / and pentamers of isophorone diisocyanate are preferred.
The molecular weight of the polyisocyanate is preferably 100 or more, more preferably 150 or more, more preferably 1,000 or less, and even more preferably 500, in terms of the balance between the strength and elastic modulus of the cured product of the composition. It is preferable that:
(B) Compound containing a hydroxyl group As a compound containing a hydroxyl group used as a raw material for urethane (meth) acrylate, polyols containing two or more hydroxyl groups are preferred, and specific examples thereof 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-hexanediol, 2-ethyl- 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,8-octa And alkylene polyols such as diol, trimethylolpropane, pentaerythritol, sorbitol, mannitol, glycerin, 1,2-dimethylolcyclohexane, 1,3-dimethylolcyclohexane, 1,4-dimethylolcyclohexane.

  In general, among these, the polyols are polyether polyols having ether bonds for forming multimers, etc., polyester polyols having ester bonds by reaction with polybasic acids or ester bonds by ring-opening polymerization of cyclic esters. Or a polycarbonate polyol having a carbonate bond by reaction with carbonate. In the present invention, when urethane (meth) acrylate is used as component 1), the polyester polyol is a compound containing a hydroxyl group. It is essential to use as at least a part of By using the polyester polyol, deformation of the cured product of the composition of the present invention due to changes in environmental humidity, in particular, warpage deformation of the laminate in which the cured product layer of the composition of the present invention is formed on the substrate is significantly reduced. be able to.

The larger the proportion by weight of the polyester polyol in the compound containing a hydroxyl group, the better. In principle, 100% by weight is optimal. However, when modification or side chain introduction is required depending on the application, it is not limited, but it is contained at least 30% by weight, more preferably 50% by weight or more.
On the other hand, the preferred content of component 1) relative to the total weight of the radiation curable composition of the present invention is 3% by weight or more, more preferably 7% by weight or more, and 50% by weight or less, more preferably 30% by weight or less. is there.

Specific examples of the polyester polyol include a reaction product of the polyol 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.
The polyether polyol can be used in combination with the polyester polyol, and specific examples thereof include polytetramethylene glycol as a ring-opening polymer of a cyclic ether such as tetrahydrofuran, in addition to the polyol multimer, Examples of the polyols include adducts of alkylene oxides such as ethylene oxide, propylene oxide, 1,2-butylene oxide, 1,3-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, and epichlorohydrin.

  Polycarbonate polyols can also be used in combination with polyester polyols. Specific examples thereof include the polyols and alkylene carbonates such as ethylene carbonate, 1,2-propylene carbonate, and 1,2-butylene carbonate. Or diphenyl carbonate, 4-methyl diphenyl carbonate, 4-ethyl diphenyl carbonate, 4-propyl diphenyl carbonate, 4,4′-dimethyl diphenyl carbonate, 2-tolyl-4-tolyl carbonate, 4,4′-diethyl diphenyl carbonate, 4,4'-dipropyldiphenyl carbonate, phenyltoluyl carbonate, bischlorophenyl carbonate, phenylchlorophenyl carbonate, phenylnaphthyl carbonate, di Diaryl carbonate such as butyl carbonate, or dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, di-t-butyl carbonate, di-n-amyl carbonate, Reaction products with dialkyl carbonates such as diisoamyl carbonate and the like can be mentioned.

The molecular weight of these polyols is preferably 15 mol% or more, more preferably 30 mol% or more of the total of polyols from the viewpoint of small curing shrinkage deformation upon radiation curing and good environmental resistance. The molecular weight is preferably 800 or more, 3,000 or less, and more preferably 2,000 or less. The molecular weight of the entire polyols is 3,500 or less, more preferably 2,500 or less, particularly 2,500 or less, optimally 1,500 or less, 200 or more, further 400 or more, especially It is preferably 600 or more. As for the polyester polyol, it is particularly preferable that the molecular weight is 800 or more.
(C) (Meth) acrylate containing hydroxyl group
The (meth) acrylate containing a hydroxyl group is a compound having both a hydroxyl group and a (meth) acryloyl group. Specifically, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) ) Acrylate, addition reaction product of glycidyl ether and (meth) acrylic acid, mono (meth) acrylate body of glycol, and the like. These may be used alone or in combination of two or more. It may be used.
The molecular weight of the hydroxyl group-containing (meth) acrylate is preferably 40 or more, more preferably 80 or more, and is preferably 800 or less, more preferably 400 or less.

(D) Method for producing urethane (meth) acrylate
A urethane (meth) acrylate having a (meth) acryloyl group can be produced by addition reaction of the polyisocyanate, the hydroxyl group-containing compound, and the hydroxyl group-containing (meth) acrylate. . In that case, it adjusts so that an isocyanate group and a hydroxyl group may become stoichiometric amount. In particular, diols are used as a compound containing a hydroxyl group, and urethane (meth) acrylate having a (meth) acryloyl group further has an advantage that adhesion and surface curing degree are further increased as a cured product of the resulting composition. There is.

  When producing urethane (meth) acrylate, the amount of the (meth) acrylate containing the hydroxyl group was combined with the compound containing the hydroxyl group and the (meth) acrylate containing the hydroxyl group. It is usually 20% by weight or more, preferably 40% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less, based on the total amount of hydroxyl group-containing compounds. According to the ratio, the molecular weight of the urethane (meth) acrylate obtained can be controlled.

The addition reaction between the polyisocyanate and the (meth) acrylate containing a hydroxyl group can be performed by any known method. For example, a mixture of a polyisocyanate, a hydroxyl group-containing (meth) acrylate and an addition reaction catalyst is usually at 40 ° C or higher, preferably 50 ° C or higher, and usually 90 ° C or lower, preferably 75 ° C or lower. Mix under. As a mixing method at that time, it is preferable to drop a mixture of a hydroxyl group-containing (meth) acrylate and an addition reaction catalyst in the presence of polyisocyanate. In addition, 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, Two or more kinds may be used in combination.
In addition, when manufacturing urethane (meth) acrylate, you may contain other components suitably other than the said polyisocyanate, the compound containing the said hydroxyl group, and the (meth) acrylate containing the said hydroxyl group. .

(E) Properties of urethane (meth) acrylate
As urethane (meth) acrylate, 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 has an aromatic ring, the radiation curable composition having an aromatic ring and the cured product thereof are colored during storage even if the resulting product is a colored product or is not colored. Or coloring may increase (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 energy rays, and therefore urethane (meth) acrylate does not have an aromatic ring. By having the structure, 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.

  For urethane (meth) acrylates that do not have aromatic rings, select polyisocyanates that do not have aromatic rings, compounds that contain hydroxyl groups that do not have aromatic rings, and (meth) acrylates that contain hydroxyl groups that do not have aromatic rings Specific examples of the polyisocyanate that can be produced by the process and have no aromatic ring include alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate. In addition, specific examples of the compound containing a hydroxyl group having no aromatic ring include alkylene polyol, alkylene polyester, and alkylene carbonate polyols, and the like, and a hydroxyl group having no aromatic ring. Specific examples of the content to (meth) acrylate, hydroxyalkyl (meth) acrylate. In addition, these 1 type may be used independently and may be used in combination of 2 or more type.

The weight average molecular weight of these urethane (meth) acrylates is preferably 1,000 or more, more preferably 1,500 or more, and more preferably 10,000 or less, and more preferably from the viewpoint of the balance between viscosity and mechanical properties. It is preferably 5,000 or less.
In the radiation curable composition of the present invention, the content of the urethane (meth) acrylate is preferably 25% by weight or more, more preferably 30% by weight or more, and 95% by weight or less. And is more preferably 90% by weight or less. If the content of the urethane (meth) acrylate is too small, moldability and mechanical strength when forming a cured product tend to be lowered, and cracks tend to occur in the cured product. The surface hardness tends to decrease.

1-2. Component 2)
In the radiation curable composition of the present invention, di (meth) acrylate is an essential component.
Among these, di (meth) acrylate which is a (meth) acrylic acid ester of two hydroxyl groups linked by 7 or less carbon-carbon bond chains is preferably used.
“Two hydroxyl groups linked by 7 or less carbon atoms” means that the number of carbon atoms in the carbon-carbon bond chain bonded to the hydroxyl group and the hydroxyl group is 7 or less. In the case where the molecular chain has a cyclic structure, it means a chain having the smallest number of carbon atoms of 7 or less among a plurality of carbon-carbon bond chains between the hydroxyl groups.

Examples of the di (meth) acrylate include butanediol di (meth) acrylate, pentanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, methylpentanediol di (meth) acrylate, and 1,6-hexanediol. Di (meth) acrylate, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ]
Examples include decane = di (meth) acrylate, nonanediol di (meth) acrylate, and decanediol di (meth) acrylate. These di (meth) acrylates may be used alone or in combination of two or more.

Preferred specific examples of the di (meth) acrylate in the present invention include butanediol di (meth) acrylate, pentanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, methylpentanediol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = di (meth) acrylate, and the like. These di (meth) acrylates may be used alone or in combination of two or more.

  Di (meth) acrylate forms a cross-linked structure with component 1) and is used for the purpose of maintaining flexibility, surface hardness and elastic modulus moderately. Among them, 7 or less skeletons of di (meth) acrylate are used. The reason why the carbon-carbon bond chain is preferable is that a molecular chain between cross-linking points formed by di (meth) acrylate has an appropriate flexibility and a cured product having a good balance between surface hardness and elastic modulus. For example, the water absorption rate of carbon-carbon bonds is low, the deformation with respect to humidity change is small, and the durability against high-temperature and high-humidity environment is high.

1-3. Compound having an isocyanurate skeleton The radiation-curable composition of the present invention preferably contains a compound having an isocyanurate skeleton. By containing a compound having an isocyanurate skeleton, the surface hardness of the cured product obtained by curing the radiation curable composition of the present invention can be further increased, and the elastic modulus can be relatively reduced. it can.
As described above, as a method of containing a compound having an isocyanurate skeleton, as described above, the component 1) is urethane (meth) acrylate and the urethane (meth) acrylate contains the isocyanurate skeleton, or has an isocyanurate skeleton. The method of adding (meth) acrylate is mentioned.

Specifically, the method of incorporating an isocyanurate skeleton into urethane (meth) acrylate is, for example, polyisocyanate which is one of the raw materials of urethane (meth) acrylate, and the total number of carbon atoms including carbon atoms in the isocyanate group is An isocyanurate skeleton triisocyanate which is a trimer of 4 to 12 diisocyanates can be used.
Among them, as a cured product of the radiation curable composition, hexamethylene diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate are three in that they have high surface hardness, low elastic modulus, and small deformation due to curing shrinkage. A monomeric isocyanurate is particularly preferred.

Specific examples of the (meth) acrylate having an isocyanurate skeleton include tris (acryloyloxyethyl) isocyanurate, tris (methacryloyloxyethyl) isocyanurate, caprolactone-modified tris (acryloyloxyethyl) isocyanurate, caprolactone-modified tris (meta) Examples include acryloyloxyethyl) isocyanurate and bis (acryloyloxyethylhydroxyethyl) isocyanurate.
When these (meth) acrylates having an isocyanurate skeleton are added, they may be added singly or in combination of two or more.

The content of the compound having an isocyanurate skeleton in the radiation curable composition of the present invention is preferably 1 × 10 ⁻⁵ mol / g or more, and more preferably 5 × 10 ⁻⁵ mol / g or more. It is particularly preferably 1 × 10 ⁻⁴ mol / g or more. Further, it is preferably 1 × 10 ⁻³ mol / g or less, more preferably 5 × 10 ⁻⁴ mol / g or less, and particularly preferably 3 × 10 ⁻⁴ mol / g or less.
If the content of the compound having an isocyanurate skeleton is too small, the surface hardness of the radiation-cured composition as a cured product is lowered. Conversely, if the content is too large, deformation due to curing shrinkage after curing tends to increase. .

  As a method of introducing the isocyanurate skeleton, when the method of incorporating the isocyanurate skeleton into the urethane (meth) acrylate is adopted, the content of the urethane (meth) acrylate having the isocyanurate skeleton is 3% by weight or more. Preferably, it is more preferably 7% by weight or more, and particularly preferably 12% by weight or more. Further, it is preferably 60% by weight or less, more preferably 40% by weight or less, and particularly preferably 30% by weight or less.

1-4. Other components in the radiation curable composition The radiation curable composition of the present invention may contain arbitrary components as long as the effects of the present invention are not impaired, and examples thereof include the following.

(A) Other (meth) acrylate compounds The composition of the present invention preferably contains a relatively low molecular weight (meth) acrylate as a component other than the above-mentioned constituents mainly for the purpose of reducing the viscosity. By containing a relatively low molecular weight (meth) acrylate, the composition becomes a liquid state having an appropriate viscosity, and a smooth coating layer with few defects can be easily formed by various coating methods. The relatively low molecular weight (meth) acrylates in the present invention are classified into monofunctional (meth) acrylates and polyfunctional (meth) acrylates.

  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) acrylate, and the like. Hydroxyalkyl (meth) acrylates, (meth) acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylate having a tricyclodecane skeleton, etc. Among them, alicyclic (meth) acrylates are preferable, and among them, hydrophobic tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, Kurohekishiru (meth) acrylate, having tricyclodecane skeleton (meth) acrylate are particularly preferred.

Examples of the polyfunctional (meth) acrylate compounds include aliphatic poly (meth) acrylates, alicyclic poly (meth) acrylates, aromatic poly (meth) acrylates, and specific examples include polyethylene glycol diacrylate. (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) Di () of alkylene oxide adducts such as ethylene oxide, propylene oxide or butylene oxide of bisphenol such as acrylate, polyisobutylene glycol di (meth) acrylate, bisphenol A, bisphenol F, or bisphenol S B) Di (meth) acrylates of hydrogenated derivatives of bisphenols such as acrylate, bisphenol A, bisphenol F or bisphenol S, blocks of various polyether polyol compounds with other compounds, or di (meth) of random copolymers (Meth) acrylates having a polyether skeleton such as acrylate, 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 (meta ) Bifunctional (meth) acrylates such as acrylate, p-bis [β- (meth) acryloyloxyethylthio] xylylene, 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenylsulfone, tri Trifunctional (meth) acrylates such as methylolpropane tris (meth) acrylate, glycerin tris (meth) acrylate, pentaerythritol tris (meth) acrylate, and tetrafunctional (meth) acrylates such as pentaerythritol tetrakis (meth) acrylate Indefinite polyfunctional (meth) acrylates such as pentafunctional or higher (meth) acrylates such as dipentaerythritol hexa (meth) acrylate.

Furthermore, as the polyfunctional (meth) acrylate in the present invention, a side chain that is not related to crosslinking when it is made into a cured product, for example, a (meth) acryloyl group like an ethyl group in trimethylolpropane tri (meth) acrylate. When a crosslinked structure is formed, it is preferable not to have a molecular chain that is not directly involved in the formation of the crosslinked structure. From this viewpoint, polyethylene glycol di (meth) acrylate, 1,3-polypropylene glycol di (Meth) acrylate, polytetramethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, octanediol di (meth) acrylate, nonanediol di (meth) acrylate, decanediol di (meth) acrylate, bis (hydroxy Methyl) tricyclo [5. .1.0 ^2,6] include decane = di (meth) acrylate, glycerol tris (meth) acrylate, pentaerythritol tetrakis (meth) acrylate, as dipentaerythritol hexa (meth) acrylate are preferable polyfunctional (meth) acrylate It is done.

These (meth) acrylates preferably have a relatively low molecular weight from the viewpoint of the balance between the viscosity and the curing shrinkage as the composition, specifically, the molecular weight is 1,000 or less, more preferably 500 or less. Is preferred. There is no particular lower limit for the molecular weight, but it is usually 100 or more.
In the radiation curable composition of the present invention, the content of the relatively low molecular weight (meth) acrylate is preferably 5% by weight or more, more preferably 10% by weight or more, and 75% by weight. The following is preferable, and it is further more preferable that it is 70 weight% or less. If the amount of the (meth) acrylate having a relatively low molecular weight is too small, the viscosity of the radiation curable composition increases, and the surface hardness of the cured product tends to decrease. Formability and mechanical strength at the time of forming are lowered, and the cured product tends to be cracked.

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

  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 is preferred.

  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 radiation curable composition of the present invention is used for an optical recording medium using a laser having a wavelength of 380 to 800 nm as a light source, the laser beam necessary for reading sufficiently passes through the cured product layer. Thus, it is preferable to select and use the type and amount of the radical generator. In this case, 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 usually 0.1 parts by weight or more, preferably 1 part by weight or more, more preferably 2 parts by weight or more, and usually 10 parts by weight with respect to a total of 100 parts by weight of the radiation curable composition. Part or less, 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. If the amount added is too small, the radiation curable composition tends not to be cured sufficiently. On the other hand, if the amount is too large, the polymerization reaction proceeds rapidly, causing problems such as an increase in optical distortion. And the hue tends to deteriorate.

When a benzophenone polymerization initiator is used, it is usually 0.5 parts by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight or less. This is because when the amount of the benzophenone-based polymerization initiator is large, the volatile components in the cured product of the radiation curable composition increase, and the film thickness may be reduced in 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. are used in combination. May be. 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 chlorine atom, sulfur atom, phosphorus atom, sodium atom, etc., but the content of these impurities is preferably small, and each content is preferably It is 100 ppm or less, 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 starting a polymerization reaction with an electron beam as radiation, the above polymerization initiator can be used, but since it is sufficiently cured without using a polymerization initiator, a radical generator or other polymerization initiator is used. It is preferable not to use.

(C) Auxiliary component
The radiation curable composition of the present invention may contain an auxiliary component such as an additive as 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 fibers, fillers metal powders and the like; carbon fiber, carbon black, graphite, carbon nanotube, a carbon material such as fullerene such as C ₆₀ (fillers, referred to as an inorganic component are collectively a carbon material such.); charge Modifiers such as inhibitors, plasticizers, mold release agents, antifoaming agents, leveling agents, anti-settling agents, surfactants, thixotropy imparting agents, epoxy group-containing compounds; pigments, dyes, hue modifiers, etc. Agents; monomers 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. It may be used 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 entire radiation-curable composition.

Among these, silica as fillers will be described in detail. In the radiation curable composition of the present invention, silica refers to silicon oxide in general, and it does not matter whether the ratio of silicon and oxygen 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 do. Among these, when used in the radiation curable composition of the present invention, silica particles dispersed in a solvent or silica particles derived and synthesized from a raw material such as alkoxysilane, because of ease of mixing and dispersion. Is preferred. Solvents include alcohols such as methanol, ethanol and propanol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, ethers such as propylene glycol methyl ether, cyclic ethers such as tetrahydrofuran, toluene, xylene and the like. Common organic solvents such as aromatics can be used.

  Although the particle diameter of the silica particles is arbitrary, the number average particle diameter measured by morphological observation using a TEM (transmission electron microscope) or the like is preferably 0.5 nm or more, more preferably 1 nm or more, Further, it 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. Silica particles are preferably ultrafine particles in order to maintain light transmission properties. However, if they are too small, the cohesiveness of ultrafine particles is extremely increased, and the transparency and mechanical strength of the cured product are extremely decreased. This is because the characteristics due to the quantum effect tend not to be remarkable.

  When forming a coating layer having a film thickness of about 20 μm or more, it is necessary to remove the dispersion medium of silica particles in order to prevent the generation of bubbles. As a method for the removal, first, a dispersion medium in which silica particles are dispersed (hereinafter referred to as “silica sol”) is uniformly mixed with (meth) acrylate or the like which is a radiation curable composition, and then an apparatus such as an evaporator is used. And a method of removing the dispersion medium while heating and reducing the pressure. The heating and decompression conditions at that time are determined in consideration of the boiling point and vapor pressure of the dispersion medium to be removed. The heating temperature is usually from room temperature to about 150 ° C., and the decompression pressure is usually 0.1 KPa. About 50 KPa. Further, the heating and decompression treatment time is usually about 15 minutes to 10 hours.

2. 2. Production method and physical properties of radiation curable composition 2-1. Method for producing radiation curable composition
The radiation curable composition of the present invention comprises:
1) A compound derived from a polyol and having a molecular weight of 500 or more, wherein the polyol contains at least one polyester polyol, and the content of all polyether skeletons and the content of all polycarbonate skeletons with respect to all polyol skeletons. Any of which is 20% by weight or less,
2) In addition to di (meth) acrylate, a compound having an isocyanurate skeleton used as necessary, other (meth) acrylate compounds, polymerization initiators, auxiliary components, etc. are stirred in a state where radiation is blocked. And then uniformly mixed.
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.

  The stirring conditions at that time are not particularly limited, but the stirring temperature is usually room temperature, but it may be heated to a temperature of usually 90 ° C. or lower, preferably 70 ° C. or lower. The speed is usually 100 rpm or more, preferably 300 rpm or more, and usually 1,000 rpm or less, and the stirring time is usually 10 seconds or more, preferably 3 hours or more, and usually 24 hours or less.

2-2. Physical Properties of Radiation Curable Composition In the present invention, the viscosity of the radiation curable composition is measured by an E type viscometer, a B type viscometer, a vibration type viscometer or the like.
The radiation curable composition of the present invention has a viscosity at 25 ° C. of 100 mPa · s or more, preferably 300 mPa · s or more, more preferably 500 mPa · s or more, and particularly preferably 1000 mPa · s or more. Moreover, it is 5000 mPa * s or less, Preferably it is 3000 mPa * s or less, More preferably, it is 2000 mPa * s or less.
If the viscosity is too small, for example, it becomes difficult to form a cured product having a film thickness of 50 μm or more,
On the other hand, when the viscosity is too large, it becomes difficult to form a cured product having a smooth surface.

  The radiation curable composition of the present invention preferably contains substantially no solvent. This is to prevent bubbles from remaining and hindering reading and writing of information. “Contains substantially no solvent” means a state in which the content of a so-called organic solvent having volatility or a low boiling point is very low, and the solvent content in the radiation-curable composition is usually 5% by weight or less. It is preferably 3% by weight or less, 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.

3. Cured product of radiation curable composition
3-1. Method for producing cured product of radiation curable composition
The cured product of the radiation curable composition in the present invention is obtained by so-called “radiation curing” in which a polymerization reaction is started by irradiation with radiation (active energy rays or electron beams). 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 term “radiation” refers to electromagnetic waves (gamma rays, X-rays, ultraviolet rays, visible rays, infrared rays, micro rays, which act on a polymerization initiator that initiates a necessary polymerization reaction to generate chemical species that initiate the polymerization reaction. Wave) or particle beam (electron beam, α-ray, neutron beam, various atomic beams, etc.). Examples of radiation preferably used in the present invention are preferably ultraviolet rays, visible rays, and electron beams, and most preferably ultraviolet rays and electron beams because energy and a general-purpose light source can be used.

When ultraviolet rays are used as radiation, it is preferable to use a photoradical generator that generates radicals by ultraviolet rays within the above-described polymerization initiation as the polymerization initiator. At this time, a sensitizer may be used in combination as necessary. The wavelength of the ultraviolet rays is usually 200 nm or more, preferably 240 nm or more, and usually 400 nm or less, preferably 350 nm or less.
As a device for irradiating ultraviolet rays, a known device such as a high-pressure mercury lamp, a metal halide lamp, or an ultraviolet lamp having a structure for generating ultraviolet rays by microwaves can be preferably used. The output of the apparatus is usually 10 W / cm or more, preferably 30 W / cm or more, and usually 200 W / cm or less, preferably 180 W / cm or less. The apparatus is usually 5 cm or more, preferably Is preferably at a distance of 30 cm or more, and usually 80 cm or less, preferably 60 cm or less, because the light deterioration, thermal deterioration, thermal deformation, etc. of the irradiated object are small.

The irradiation intensity of the radiation, usually 0.1 J / cm ² or more, preferably 0.2 J / cm ² or more, and usually 20 J / cm ² or less, preferably 10J / cm ² or less, more preferably 5 J / cm ² or less, more preferably 3J / cm ² or less, particularly preferably irradiated with 2J / cm ² or less. If irradiation intensity is in this range, it can select suitably by the kind of radiation-curable composition.

  The irradiation time of radiation is usually 1 second or longer, preferably 10 seconds or longer, and usually 3 hours or shorter, and preferably 1 hour or shorter in terms of promoting the reaction and productivity. When the irradiation energy or irradiation time of radiation 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 of the radiation 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 radiation spreads in all directions is usually used. The irradiation of radiation is usually carried out with the radiation source fixed and left in a state where the radiation-curable composition shaped in the mold is fixed and left or transported by a conveyor. It is also possible to use a radiation curable composition as a coating liquid film on a suitable substrate (for example, resin, metal, semiconductor, glass, paper, etc.), and to cure the coating liquid film by irradiation with radiation. is there.

  In addition, when an electron beam is used as radiation, the electron beam irradiation apparatus used for irradiation is not particularly limited, and 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 usually 10 kV or more, preferably 100 kV or more, and usually 1,000 kV or less, 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.

3-2. Properties of cured products of radiation curable compositions
The cured product of the radiation curable composition of the present invention usually exhibits insoluble and infusible properties in a solvent or the like, and has properties that are advantageous for the use of optical members even when it is thickened. It is preferable that the degree of curing is excellent. 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. preferable. Further, the smaller the curing shrinkage, the better.

The film thickness of the radiation cured product of the present invention 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 it is 115 micrometers or less. This is because the balance between the influence on the reading and writing of information by dust and the transmittance is good.
The light transmittance of the radiation cured product of the present invention is as follows: when a thin film layer of a cured product having a thickness of 0.1 mm obtained by irradiating 1 J / cm ² of radiation is formed, the optical path length at a wavelength of 400 nm is 0.1 mm. The light transmittance is 85% or more, preferably 89% or more, and the upper limit is not limited. If the light transmittance is too low, the transparency as a cured product is inferior. For example, when used in an optical recording medium, errors increase when reading recorded information. 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 radiation-cured product of the present invention within the above range, it is preferable to use a material having a high light transmittance as each component constituting the radiation-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 effective in order not to reduce 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 effective in order not to reduce the light transmittance in the ultraviolet region.

The radiation cured product of the present invention preferably has a tensile elastic modulus of 500 MPa or more when a thin film layer of a cured product having a thickness of 0.1 mm obtained by irradiation with 1 J / cm ² of radiation is formed. Further, it is preferably 1,000 MPa or more, more preferably 2,000 MPa or less, and further preferably 1,800 MPa or less. If the tensile modulus is too small, the load resistance is liable to be insufficient. On the other hand, if the tensile modulus is too large, the warping resistance is lowered, deformation occurs, and when the laminate is formed, delamination tends to occur. .

Here, the tensile elastic modulus means an elastic modulus when a 0.1 mm thick film is formed and a tensile test is performed at a tensile speed of 1 mm / min using a tensile strength tester.
The hardness of the radiation-cured product of the present invention is usually 6B or more, preferably 4B or more, more preferably B or more, and particularly preferably HB or more as a surface hardness according to a pencil hardness test in accordance with JIS K5400.

3-3. Application of cured product of radiation-curable composition The radiation-cured product of the present invention has good transparency and has excellent functional properties such as dimensional stability and surface hardness, and can be used for various applications. . Specific examples include various lenses such as spectacle lenses, optical connector microlenses, and light-emitting diode condensing lenses, optical switches, optical fibers, optical branching in optical circuits, junction circuits, optical multiple branching circuits, luminous intensity adjusters, etc. Optical communication components, liquid crystal substrates, touch panels, light guide plates, retardation plates, various display materials, optical disc substrates, optical disc film and coating applications, and other optical communication materials such as optical adhesives , Functional film, antireflection film, optical multilayer film (selective reflection film, selective transmission film, etc.), super-resolution film, ultraviolet absorption film, reflection control film, optical waveguide, and identification function printing surface, etc. Applications are listed.

  Although the cured product of the radiation curable composition of the present invention can be used as an optical material itself, such as resin, glass, ceramics, inorganic crystal, metal, semiconductor, diamond, organic crystal, paper pulp, wood, etc. It is also possible to form a thin film on an arbitrary substrate and to have a specific function as a part of the optical material. In the latter case, the laminate is usually used in the form of an arbitrary thin film made of a material different from the cured product.

  When used as the above laminate, the film thickness of the cured film of the radiation curable composition of the present invention has a lower limit of usually 0.05 μm in terms of mechanical strength and optical properties, preferably 0. 0.1 μm, more preferably 0.5 μm, still more preferably 5 μm, and most preferably 25 μm. On the other hand, the upper limit of the film thickness is usually 3000 μm, preferably 2000 μm, more preferably 1000 μm, still more preferably 200 μm, and most preferably 100 μm, from the viewpoint of thin film processability and cost-effective balance. There is no limitation on the shape of the thin film, but it is not necessarily flat, and may be formed on a base of an arbitrary shape such as a spherical shape, an aspherical curved surface shape, a cylindrical shape, a conical shape, or a bottle shape. Good.

  When the cured product of the radiation curable composition of the present invention is used as a thin film, a known coating method such as spin coating, dip coating, roll coating, bar coating, die coating, gravure coating, or screen printing is appropriately used. I can do it. The radiation curable composition of the present invention has a viscosity of 100 to 5000 mPa · s at 25 ° C., and particularly has a viscosity suitable for forming a coating layer having a thickness of about 25 to 100 μm. Spin coating and dip coating are suitable as a method for forming a coating layer having a thickness of about 25 to 100 μm. However, for optical recording media, film thickness uniformity in the circumferential direction is often important. In that case, application by spin coating is particularly preferred. Further, the cured product of the radiation curable composition of the present invention has a relatively high transparency with a light transmittance of 85% or more at a wavelength of 400 nm of the cured product having a thickness of 0.1 mm. It can be suitably used as a protective layer for a recording medium.

When the cured product of the radiation curable composition of the present invention is used as a thin film, a hard coat layer is further formed on the thin film layer made of the cured product of the radiation curable composition of the present invention for the purpose of improving surface hardness and antifouling property. It is possible to create a laminated body provided with. The kind of the hard coat layer is not particularly limited, and a known hard coat layer can be used as a general hard coat layer. In the present invention, the surface hardness is preferably B or more, more preferably HB or more, still more preferably F or more,
Most preferably, it is H or more. The measurement of the surface hardness can be the same as the method for measuring the surface hardness of the cured product of the radiation curable composition of the present invention.

The hard coat layer preferably has a light transmittance at a wavelength of 400 nm of 80% or more, more preferably 85% or more, and further preferably 89% or more. The measurement of the light transmittance is the same as the method for measuring the light transmittance of the cured product of the radiation curable composition of the present invention described above.
Moreover, it is preferable that the contact angle with respect to water is 90 degrees or more, More preferably, it is 100 degrees or more. Thereby, the antifouling property of a laminated body can be made high. The measurement of the contact angle with respect to water can be carried out by a known method using a contact angle meter or the like.

The film thickness of the hard coat layer is usually 0.5 μm or more, preferably 1 μm or more, more preferably 1.5 μm or more. Further, it is usually 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less.
The hard coat layer of the laminate having the cured product of the radiation curable composition of the present invention preferably has antifouling properties such as a high contact angle with water.

  As hard coat materials having antifouling properties, radiation curing containing a silicone compound or fluorine compound as a stain resistance imparting agent and containing inorganic components such as polyfunctional (meth) acrylate monomers, epoxy compounds, inorganic nanoparticles, etc. The composition is preferably used. Specifically, the stain resistance imparting agent includes a polymer having a silicone skeleton such as an organopolysiloxane skeleton, a radiation curable compound having a silicone skeleton and an acrylic group, a silicone compound such as a silicone surfactant, and a fluorine atom. Examples thereof include fluorine compounds such as a polymer to be contained, a radiation curable compound having a fluorine atom and an acryl group, and a fluorine-based surfactant.

The antifouling hard coat agent that can be used in the present invention is basically not particularly limited as long as it is an active energy ray-curable hard coat agent containing a polysiloxane or a stain resistance imparting agent containing a fluorine-containing group. It is preferable that active energy ray curability is imparted to the contamination imparting agent. Specific examples include the following.
(1) An active energy ray-curable hard coating agent containing a polysiloxane compound having an active energy ray-curable group at the terminal and / or a fluorine compound and not containing an inorganic component.
(2) An active energy ray-curable hard coating agent containing an active energy ray-curable group and a polymer containing a polysiloxane unit and / or an organic fluorine group unit.
(3) An active energy ray-curable hard coat agent containing a polysiloxane compound having an active energy ray-curable group in the side chain and / or a fluorine compound.

  Such a hard coat layer is, for example, a radiation curable monomer or / and oligomer having at least one functional group selected from the group consisting of (meth) acryloyl groups, vinyl groups, and mercapto groups, fluorine, and the like. It can form using the radiation-curable composition for hard-coat layer formation containing a compound, a silicone compound, the above-mentioned silica particle, etc. Specifically, it can be formed by applying the radiation-curable composition for forming a hard coat layer onto a layer of a cured product comprising the composition of the present invention and curing the composition.

  As a preferable composition of the radiation curable composition for forming the hard coat layer, for example, the radiation curable component is 50 parts by weight or more and 99 parts by weight or less, and the water / oil repellency / low friction agent is 0.1 parts by weight or more. , 15 parts by weight or less, and 0.1 parts by weight or more and 10 parts by weight or less of the photopolymerization initiator are added to the composition (total 100 parts by weight) containing 0 to 50 parts by weight of the inorganic component, and further necessary as appropriate. Depending on the case, those diluted with a solvent and / or a reactive diluent may be used. In addition, it is not limited to the said composition, Unless it deviates from the summary of this invention, it is possible to change the said composition arbitrarily.

Moreover, the application | coating method of the radiation curable composition for hard-coat layer formation at the time of forming the said hard-coat layer is not specifically limited, For example, it can be set as general application methods, such as a spin coat method. Moreover, it does not specifically limit about the radiation used for hardening of the said radiation-curable composition for hard-coat layer formation, For example, it can be made to be the same as that of the radiation used in the case of radiation curing of the composition of this invention.

4). Optical Recording Medium The radiation curable composition and the radiation cured product 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 that are generally used include read-only media (ROM media), write-once media that can only be recorded once (Write Once media), and rewritable media that can be repeatedly erased. There are types of media (Rewritable media) and the like, but the radiation curable composition of the present invention and the radiation cured product thereof can be applied to any of them.

  These optical recording media employ a layer structure according to their intended use. For example, in a read-only medium, a single layer containing, for example, a metal such as aluminum, silver, or gold is usually formed on a substrate on which unevenness for reproduction is formed, and in a write-once medium, A recording / reproducing functional layer in which a reflective layer containing a metal such as aluminum, silver, and gold and a recording layer containing an organic dye are laminated in this order on the substrate is usually formed. In a medium, a reflective layer containing a metal such as aluminum, silver, or gold, a dielectric layer, a recording layer made of a phase change material, and a dielectric layer are usually stacked in this order on a substrate. The radiation curable composition of the present invention and the radiation cured product thereof are formed on a single layer in a read-only medium, on a recording / reproduction functional layer in a write-once medium, and Rewritable media It is suitable for use as a protective layer formed on the definitive recording and reading layer.

  On the other hand, the wavelength of laser light as recording / reproducing light for recording / reproducing of an optical recording medium is light having an optimum wavelength depending on the standard such as CD, DVD, BD (Blu-ray Disc (registered trademark)). With the recent spread 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 is also 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. This is an optical recording medium using 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. The radiation-curable composition of the invention and the radiation-cured product thereof are particularly preferably used.

  The radiation-curable composition of the present invention and the optical recording medium in which the radiation-cured product is used have, for example, a two-layer structure having two recording layers and two reflection layers. Also good. 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.

  Further, in the optical recording medium having the cured product of the radiation curable composition of the present invention as a protective layer, it is preferable to provide a hard coat layer on the protective layer as described above.

Example 1
(Preparation of radiation curable composition A)
In a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, thermometer, 13.3 g of isophorone diisocyanate, 26.4 g of hexamethylene diisocyanate trimer ("Tronate HDT" manufactured by Rhodia) and 10 mg of dibutyltin laurate The mixture was heated to 70-80 ° C. in an oil bath and gently stirred until the temperature became constant. When the temperature becomes constant, 29.8 g of a polyester polyol (“Kuraray polyol P-1010” manufactured by Kuraray Co., Ltd .; molecular weight 1000) is dropped with a dropping funnel, and the mixture is stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature was lowered to 70 ° C., a mixture of 10.5 g of hydroxyethyl acrylate and 15 mg of methoquinone was added dropwise with a dropping funnel. When the addition was completed, the temperature was kept at 80 ° C. and stirred for 10 hours to obtain urethane acrylate oligomer (A). Was synthesized. The urethane acrylate oligomer (A) has an isocyanurate skeleton and has a molecular weight of 500 or more. 60.0 g of tetrahydrofurfuryl acrylate (manufactured by Osaka Organic Chemical Co., Ltd.) to the synthesized urethane acrylate oligomer (A), di (meth) acrylate ester of two hydroxyl groups linked by 7 or less carbon-carbon bond chains As a (meth) acrylate, 60.0 g of 1,6-hexanediol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) and 6.0 g of 1-hydroxycyclohexyl phenyl ketone (manufactured by Nippon Siebel Hegner Co., Ltd.) were added and mixed for 3 hours for dilution. A uniform liquid radiation curable composition A was prepared.

(Preparation of radiation curable composition B)
In the preparation of the radiation curable composition A, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) was used instead of 1,6-hexanediol diacrylate. A-DCP ") was used in the same manner to prepare a uniform liquid radiation-curable composition B.
(Preparation of radiation curable composition C)
In the preparation of the radiation curable composition A, di (meth) which is a (meth) acrylic acid ester of two hydroxyl groups linked by nine carbon-carbon bond chains instead of 1,6-hexanediol diacrylate A uniform liquid radiation curable composition C was prepared in the same manner except that nonanediol diacrylate (“A-NOD-N” manufactured by Shin-Nakamura Chemical Co., Ltd.) was used as the acrylate.

(Preparation of radiation curable composition D)
The synthesis of the urethane acrylate oligomer (A) in the preparation of the radiation curable composition A was carried out in the same manner except that a polyether polyol (“PTMG1000” manufactured by Mitsubishi Chemical Corporation; molecular weight 1000) was used instead of the polyester polyol. A radiation curable composition D was prepared.
(Preparation of radiation curable composition E)
In the synthesis of the urethane acrylate oligomer (A) in the preparation of the radiation curable composition A, it was carried out in the same manner except that polycarbonate polyol (“Kuraray polyol C-1090” manufactured by Kuraray Co., Ltd .: molecular weight 1000) was used instead of polyester polyol. A uniform liquid radiation curable composition E was prepared.

(Preparation of composition for hard coat layer)
90 g of dipentaerythritol (hexa / penta) acrylate (trade name: Kayalad DPHA (manufactured by Nippon Kayaku Co., Ltd.)) as a curable composition for a hard coat layer, and methyl methacrylate (water repellent / oil repellent / low friction agent) MMA), perfluorooctylethyl methacrylate, X-22-167B (both end mercapto polydimethylsiloxane, manufactured by Shin-Etsu Chemical Co., Ltd.) and glycidyl methacrylate (GMA) 25/40/5/30 (weight ratio) copolymer 28.57 g of acrylic acid adduct (35% PGM solution) and 2 g of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator were added, and PGMA was added in an amount corresponding to a solid content of 40% by weight. Stirring for a time, the composition for hard-coat layers was prepared.
About said radiation-curable composition, the characteristic was evaluated with the following method.
(viscosity)
The viscosity of the radiation curable composition A was measured using an E-type viscometer in a constant temperature and humidity chamber at 25 ° C. and 65% RH.

(surface hardness)
After applying the radiation curable composition A on a 100 mm square and 3 mm thick glass plate using a spin coater, the irradiation dose is 1 J / cm ² using a high pressure mercury lamp (“J-cure 100” manufactured by JATEC). The film was cured by irradiating with UV light to prepare a thin film layer of a cured product having a film thickness of 100 μm. On the thin film layer of the cured product, the composition for the hard coat layer was applied using a spin coater, dried in an oven at 60 ° C. for 2 minutes, and then irradiated with ultraviolet rays having a dose of 1 J / cm ² using a high-pressure mercury lamp. Was hardened by irradiation to form a hard coat layer with a thickness of 2 ± 0.3 μm, and the surface of the hard coat layer was measured for pencil hardness in accordance with JIS K5400.

(Light transmittance)
The radiation curable composition A was applied onto a 100 mm square, 3 mm thick glass plate coated with fluorine using a spin coater, and then the wavelength was measured using a high pressure mercury lamp (“J-cure 100” manufactured by JATEC). A cured thin film layer having a thickness of 100 μm was prepared by irradiating with ultraviolet rays having an irradiation amount of 1 J / cm ² at 365 nm. After the thin film layer of the cured product was peeled from the glass plate, the optical path length at a wavelength of 400 nm was 0.1 mm for the peeled thin film layer of the cured product using an ultraviolet / visible absorptiometer (manufactured by Hewlett-Packard; HP8453 type). The light transmittance per hit was measured.

(Environmental resistance test)
An Ag—Cu—Au reflective layer having a thickness of 100 nm was formed by sputtering on a smooth polycarbonate resin substrate surface having a diameter of 120 mm and a thickness of 1.1 mm.
A radiation curable composition A was applied to the surface of the reflective layer with a spin coater so as to have a thickness of 100 μm, and using a high-pressure mercury lamp (manufactured by JATEC; J-cure 100), an irradiation amount of 1000 mJ / cm at a wavelength of 365 nm. ^The test disc was obtained by curing by irradiating with ultraviolet ray No. ² .
After storing this test disk in an environment of 25 ° C. and 45% RH for 24 hours, the warp a ₀ of the disk was measured at a position 35 mm from the center of the disk by a displacement sensor (manufactured by Keyence Corporation; model number “LT-9010”). It was determined by measuring the displacement. However, the case of concave warpage on the cured product layer side was positive, and the case of convex warpage was negative.

Thereafter, the test disk is stored in a constant temperature and humidity tester set at 80 ° C. and 80% RH for 100 hours, and then the test disk is taken out and stored in a 25 ° C. and 45% RH environment for 24 hours. warping a _1, in the same manner as described above was measured to determine the post-resistance environmental test warp a (mm) according to the following.

a = | a ₀ −a ₁ |
The warp amount of the optical recording medium according to the above test is practically preferably 0.1 mm or less in order to perform stable recording and reproduction.
(Anti-humidity deformation evaluation test)
A test disk was prepared in the same manner as described above, and after standing for 3 days in an environment set at 25 ° C. and 45% RH (relative humidity), the test disk was kept at 25 ° C. and a constant temperature set at 90% or more RH. It was stored in a constant humidity tank for 3 days. Thereafter, the test disk is taken out in an environment set to 25 ° C. and 45% RH, and the warp d ₀ of the disk immediately after removal is set at a position 35 mm from the center of the disk by a displacement sensor (manufactured by Keyence Corporation; model number “LT-9010”). It was obtained by measuring the displacement of. However, the case of concave warpage on the protective layer side was positive, and the case of convex warpage was negative.

Thereafter, the warp d _1, d _2, d _{4, and} d ₆ of the disk for 1 hour, 2 hours, 4 hours, and 6 hours were obtained by measurement, and D _{1 to} D ₆ were calculated by the following equations.
D ₁ = | d ₁ -d ₀ |
D ₂ = | d ₂ −d ₀ |
D ₄ = | d ₄ −d ₀ |
D ₆ = | d ₆ -d ₀ |
The maximum value among D ₁ , D ₂ , D ₄ , and D ₆ was defined as the “humidity deformation value” of this disk.

The humidity deformation value of the optical recording medium by the above test is practically preferably 0.06 mm or less in order to perform stable recording and reproduction.
(Polyether skeleton content, polycarbonate skeleton content)
The polyether skeleton content (% by weight) and the polycarbonate skeleton content (% by weight) relative to the total polyol skeleton were defined as the polyether skeleton content and the polycarbonate skeleton content, respectively.

The above characteristic evaluation results are summarized in Table 1. In Table 1, “diacrylate carbon number” describes the carbon number of the carbon chain connecting the two hydroxyl groups of the diol esterified with acrylic acid in the structure of the diacrylate contained. Is.
(Example 2)
In Example 1, it carried out similarly to Example 1 except having used the radiation curable composition B instead of the radiation curable composition A. FIG. The characteristic evaluation results are summarized in Table 1.

(Example 3)
In Example 1, it carried out similarly to Example 1 except having used the radiation curable composition C instead of the radiation curable composition A. FIG. The characteristic evaluation results are summarized in Table 1.
(Comparative Example 1)
In Example 1, it carried out similarly to Example 1 except having used the mixture which mixed the radiation curable composition A and the radiation curable composition D by the ratio of 7: 3 instead of the radiation curable composition A. It was. The characteristic evaluation results are summarized in Table 1.
(Comparative Example 2)
In Example 1, it carried out similarly to Example 1 except having used the mixture which mixed the radiation-curable composition A and the radiation-curable composition E in the ratio of 7: 3 instead of the radiation-curable composition A. It was. The characteristic evaluation results are summarized in Table 1.

When the results of Comparative Examples 1 and 2 and Examples 1 to 3 are compared, the following is clear. That is, in the present invention, by containing the polyester skeleton and diacrylate, and by making the content of the polyether skeleton and the polycarbonate skeleton below a specific amount, the deformation value with respect to environmental humidity change can be reduced, and By making the carbon number of diacrylate 7 or less, the deformation value after the environmental resistance test can be reduced at the same time.

(Evaluation results)
In Examples 1, 2, and 3, the warpage after the environmental resistance test is 0.1 mm or less, and the evaluation results of the deformation value against humidity are both 0.06 mm or less, which is deformed with respect to changes in temperature and humidity. A good disk with a small amount of was obtained. In particular, in Examples 1 and 2, compared to Example 3 containing di (meth) acrylate which is a (meth) acrylic acid ester of two hydroxyl groups linked by nine carbon-carbon bond chains, It can be seen that the warpage after the environmental test is small and the warpage can be reduced by setting the number of carbon-carbon bond chains to 7 or less. On the other hand, in Comparative Example 1, when the content of the polyether skeleton exceeds 20 wt%, although the warpage after the environmental resistance test is small, the deformation value against humidity is large and the results are inferior to Examples 1 and 2. became. Further, in Comparative Example 2, when the content of the polycarbonate skeleton exceeded 20 wt%, the warpage after the environmental resistance test and the deformation value against humidity were both large, resulting in inferior results to Examples 1 and 2.

Claims (9)

A radiation curable composition having a viscosity at 25 ° C. of 100 to 5000 mPa · s, a light transmittance at a wavelength of 400 nm of a cured product having a thickness of 0.1 mm of 85% or more,
1) A compound derived from a polyol and having a molecular weight of 500 or more, wherein the polyol contains at least one polyester polyol, and the content of all polyether skeletons and the content of all polycarbonate skeletons with respect to all polyol skeletons. A compound that is 20% by weight or less,
2) A radiation curable composition containing di (meth) acrylate.   1) The radiation curable composition according to claim 1, wherein the compound having a molecular weight of 500 or more derived from a polyol is (meth) acrylate. The radiation curable composition according to claim 1 or 2, wherein the di (meth) acrylate is a (meth) acrylic acid ester of two hydroxyl groups linked by 7 or less carbon-carbon bond chains. Composition. The di (meth) acrylate is butanediol di (meth) acrylate, pentanediol di (meth) acrylate, methylpentanediol di (meth) acrylate, hexanediol di (meth) acrylate and bis (hydroxymethyl) tricyclo [5.
2.1.0 ^2,6 ] Decane = one or more di (meth) acrylates selected from the group consisting of di (meth) acrylates, according to any one of claims 1 to 3 Radiation curable composition.   The radiation curable composition according to claim 1, wherein the polyester polyol contains a polyester polyol having a molecular weight of 800 or more.   1) The radiation curable composition according to any one of claims 1 to 5, wherein the compound having a molecular weight of 500 or more derived from a polyol is urethane (meth) acrylate.   The radiation curable composition according to claim 1, comprising a compound having an isocyanurate skeleton.   The radiation curable composition according to claim 7, wherein the compound having an isocyanurate skeleton is urethane (meth) acrylate.   Hardened | cured material of the radiation-curable composition in any one of Claims 1-8.