JPH05135405A - Ultraviolet curing type resin composition for optical disk - Google Patents

Abstract

PURPOSE:To provide an optical disk substrate which enables recording, reproducing and erasing by light and more specifically the UV curing type resin compsn. for optical disks constituted by forming a UV curing type resin having a specific compsn. CONSTITUTION:Urethane acrylate, a monofunctional vinyl compd. having the glass transition temp. at the time of independent polymn. within 150 to 180 deg.C range, multifunctional acrylate, and a photopolymn. initiator are incorporated into the which does not generate wrinkles and cracks in a high-temp. and high- humidity test, does not attack a recording film, does not generate clouding and yellowing and has the good adhesion to a base is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to recording / reproducing,
The present invention relates to an erasable optical disc substrate, and more particularly, to an ultraviolet curable resin composition for an optical disc, which uses an ultraviolet curable resin having a specific composition.

[0002]

2. Description of the Related Art Guide grooves are formed on the surface of an optical recording medium for the purpose of guiding a laser beam. Conventionally, two methods are known as methods for forming the guide groove.

One method is polycarbonate (PC)
This is a method of performing injection molding using a thermoplastic resin such as polymethacrylate (PMMA) and a mold provided with unevenness of the guide groove, and forming the substrate and transferring the guide groove at once.

Another method is to apply a UV-curable resin on a mold having guide groove irregularities, place a glass substrate on it, spread the resin with the substrate, and irradiate the resin with UV rays. By curing and peeling from the mold,
A method of forming a guide groove on a substrate, a so-called 2P (Pho
to Polymerization) method.

The former method has the advantages of excellent mass productivity and low cost, but has poor transferability of the guide groove shape. Further, since a thermoplastic resin such as polycarbonate (PC) or polymethacrylate (PMMA) is used, the birefringence is large. In addition, deformation due to heat and moisture occurs greatly. Furthermore, since the plastic substrate has air permeability, when the recording film is formed on the molded substrate, the recording layer is corroded by moisture or oxygen under high temperature and high humidity,
It also has a drawback that the recording characteristics are deteriorated with time, and thus lacks long-term reliability as an optical disk substrate.

On the other hand, the latter method has excellent transferability of the shape of the guide groove, and since glass can be used, there is no birefringence,
It is possible to manufacture an optical disk substrate that is not deformed or deteriorated by heat, moisture, and the like.

Generally, the UV curable resin used in the 2P method is (a) a photoradical polymerizable composition containing a photoradical polymerizable prepolymer, a monomer and a photoradical polymerization initiator as main components, and (b) a photoradical. A cationically polymerizable prepolymer, a cationic photopolymerization composition containing a monomer and a cationic photopolymerization initiator as main components, (c) a radical photopolymerization composition,
And a composition that is cured by ultraviolet light, such as a composition obtained by mixing a cationic photopolymerization composition.

Further, since the optical disk is required to have high reliability for a long time, the moldability is good and the guide characteristics are required when the ultraviolet curable resin composition is used as a material for forming the guide groove. In order to improve the transfer accuracy of the groove, the releasability from the mold after UV curing should be good, and the adhesiveness and transparency to the support should not deteriorate over time under high temperature and high humidity. It is required that neither cracks nor cracks occur.

[0009]

As an ultraviolet curable resin composition conventionally used in the 2P method, for example, JP-A-63-210118 and JP-A-2-118930 are available.
In the publication, a mixture of urethane acrylate, epoxy acrylate, low molecular weight polyfunctional acrylate and the like are used.

However, these materials are (1) an ultraviolet curable resin layer formed on a substrate by sputtering heat (50 to 60 ° C.) when a recording film is formed on the molded substrate by a sputtering method or the like. Wrinkles are generated. (2) When the molded substrate is formed and left under high temperature and high humidity (80 ° C., 85% RH) for 100 hours, wrinkle growth of the UV curable resin layer and generation of cracks are noticeable. Due to the above problem, a highly reliable optical disk substrate cannot be provided.

The problem to be solved by the present invention is the characteristics required when the UV curable resin composition is used in the 2P method, and abnormalities in appearance such as wrinkles and cracks occur over time under high temperature and high humidity. It is to provide an optical disk substrate characterized by not doing.

[0012]

In order to solve the above-mentioned problems, the present invention is directed to (1) urethane acrylate, (2) monofunctional glass transition temperature (Tg) during homopolymerization in the range of 150 to 180 ° C. Vinyl compounds, (3) polyfunctional (meta)
Provided is an ultraviolet-curable resin composition for an optical disk, which contains an acrylate and (4) a photopolymerization initiator.

The urethane acrylate used in the present invention may be one obtained by reacting a vinyl compound having a hydroxyl group with an isocyanate compound by a known method.

As the vinyl compound having a hydroxyl group, for example, hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, phenoxyhydroxypropyl acrylate, butoxyhydroxypropyl acrylate, pentaerythritol acrylate, dipentaerythritol monohydroxypentaacrylate. , Trimethylolpropane diacrylate, dipropylene glycol monoacrylate, 1,6-hexanediol monoacrylate, glycerin diacrylate, caprolactone modified 2-hydroxyethyl acrylate, stearic acid modified pentaerythritol diacrylate, polyethylene glycol monoacrylate, polypropylene glycol mono Acrylate, Polite Ramethylene glycol monoacrylate, monoacrylate of copolymer of propylene oxide and ethylene oxide, monoacrylate of copolymer of tetrahydrofuran and propylene oxide, monoacrylate of copolymer of tetrahydrofuran and ethylene oxide, ethylene oxide addition of bisphenol A And monoacrylate of propylene oxide adduct of bisphenol A and the like.

Vinyl compounds having these hydroxyl groups are
They may be used alone or in combination of two or more.

Examples of the isocyanate compound include:
Tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, trimethylhexamethylene diisocyanate,
1,5-naphthalene diisocyanate, tolidine diisocyanate, p-phenylene diisocyanate, lysine diisocyanate and the like can be mentioned.

These isocyanate compounds may be used alone or in combination of two or more kinds.

Among the urethane acrylates composed of these vinyl compounds having hydroxyl groups and isocyanate compounds, 2-hydroxypropyl acrylate (HPA)
And urethane acrylates consisting of hexamethylene diisocyanate (HDI) are particularly preferred.

The proportion of urethane acrylate used in the ultraviolet-curable resin composition for optical disks of the present invention is 25-3.
A range of 5% by weight is preferred.

The monofunctional vinyl compound used in the present invention having a glass transition temperature (Tg) during homopolymerization in the range of 150 to 180 ° C. is not particularly limited, and examples thereof include N-vinyl-2-pyrrolidone and iso Examples include bornyl methacrylate.

The glass transition temperature (Tg) during homopolymerization in the ultraviolet-curable resin composition for optical disks of the present invention is 150.
The proportion of the monofunctional vinyl compound used in the range of ˜180 ° C. is preferably in the range of 15 to 40% by weight.

As the polyfunctional (meth) acrylate used in the present invention, for example, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, Poly (meth) acrylates such as trimethylolpropane, glycerin and pentaerythritol; Di- or tri (meth) acrylate of triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane; neopentyl Di (meth) acrylate of diol obtained by adding 2 moles or more of ethylene oxide or propylene oxide to 1 mole of glycol; dipentaerythritol (Meth) acrylate, tris -
Poly (meth) of (hydroxyethyl) -isocyanuric acid
Acrylate, di (meth) acrylate of di- (hydroxyethyl) -dicyclopentadiene, neopentyl glycol di (meth) acrylate pivalate, caprolactone-modified neopentyl glycol di (meth) acrylate hydroxypivalate, linear aliphatic di ( Examples thereof include (meth) acrylate and polyolefin-modified neopentyl glycol di (meth) acrylate.

Among these polyfunctional (meth) acrylates, bifunctional acrylates are preferable from the viewpoint of coating strength and adhesion. The use of a trifunctional or higher functional (meth) acrylate is not preferable because the coating film obtained tends to become hard and brittle.

The polyfunctional (meth) acrylate may be used alone or in combination of two or more kinds.

The proportion of the polyfunctional acrylate used in the ultraviolet-curable resin composition for optical disks of the present invention is 25-60.
A weight% range is preferred.

The photopolymerization initiator used in the present invention includes:
For example, 2-hydroxy-2-methyl-1-phenylpropan-1-one (“Darocur 117 manufactured by Merck & Co., Inc.
3 "), 1-hydroxycyclohexyl phenyl ketone (" Irgacure 184 "manufactured by Ciba-Geigy), 1-
(4-Isopropylphenyl) -2-hydroxy-2-
Methylpropan-1-one (Merck & Co. "Darocur 1
116 "), benzyl dimethyl ketal (" Irgacure 651 "manufactured by Ciba-Geigy), 2-methyl-1-
[4- (Methylthio) phenyl] -2-morpholinopropanone-1 (“Irgacure 90 manufactured by Ciba Geigy”)
7 ”), 2,4-diethylthioxanthone (“ Kayacure DETX ”manufactured by Nippon Kayaku Co., Ltd.) and ethyl p-dimethylaminobenzoate (“ Kayacure-EPA ”manufactured by Nippon Kayaku Co., Ltd.)
And a mixture of isopropyl thioxanthone (“CANTACURE ITX” manufactured by Ward Prekinsop Co.) and ethyl p-dimethylaminobenzoate.

These photopolymerization initiators may be used alone or in combination of two or more kinds.

The proportion of the photopolymerization initiator used in the ultraviolet-curable resin composition for optical disks of the present invention is preferably in the range of 1 to 5% by weight.

The glass transition temperature in homopolymerization is 150.
When a UV-curable resin composition obtained by mixing a monofunctional vinyl compound in the range of 180 ° C. to 180 ° C. with urethane acrylate is used as the UV-curable resin composition for forming guide grooves, heat resistance is improved. Since it is a monofunctional acrylate, the resin will not be too hard and will be easily peeled off from the stamper during molding, and no unreasonable force will be applied during mold release, so it is possible to reduce the shape defects of the transferred guide groove. it can. Further, the substrate using the ultraviolet curable resin composition of the present invention, wrinkles even when left under high temperature and high humidity for a long time, surface changes such as cracks do not occur, without damaging the recording film layer,
Can maintain high adhesion.

[0030]

EXAMPLES The present invention will be described in more detail below with reference to examples.

(Example 1) (A) Urethane acrylate composed of 2-hydroxypropyl acrylate (HPA) and hexamethylene diisocyanate (HDI) 30 parts by weight (B) N-vinyl-2-pyrrolidone (Toa Gosei Kagaku Kogyo Co., Ltd.) Made: trade name "M-150") 37 parts by weight neopentyl glycol diacrylate (manufactured by Nippon Kayaku Co., Ltd .: trade name "NPGDA") 30 parts by weight (C) Photopolymerization initiator (manufactured by Ciba-Geigy Japan: trade name " Irgacure 184 ") 3 parts by weight The above (A), (B) and (C) were mixed to obtain an ultraviolet curable resin composition.

The obtained UV-curable resin composition was treated with 2P.
It was applied on a stamper using a molding machine (manufactured by Dainippon Ink and Chemicals, Inc.), the resin was spread by a glass substrate that had been treated with a primer, and the resin was cured by irradiation with ultraviolet rays in nitrogen. After that, the substrate on which the guide groove was formed was peeled from the stamper to obtain an optical disc substrate.

Si is sputtered on the obtained substrate.
N film 1,000 angstrom, TbFeCo film 30
A recording film consisting of a four-layer film of 0 Å, SiN film 300 Å and Al film 500 Å was formed, and as a result of microscopic observation of the cured resin layer immediately after sputtering, no wrinkles, cracks, etc. were found. It was Also, in high temperature and high humidity (80 ° C, 85% RH)
After leaving it to stand for 000 hours, it was observed with a microscope that no wrinkles, cracks or the like were observed and no influence on the recording film was observed.

(Example 2) (A) Urethane acrylate composed of 2-hydroxypropyl acrylate (HPA) and hexamethylene diisocyanate (HDI) 30 parts by weight (B) Isobornyl methacrylate (manufactured by SARTOMER: trade name "SR") -423 ") 30 parts by weight neopentyl glycol diacrylate (manufactured by Nippon Kayaku Co., Ltd .: trade name" NPGDA ") 37 parts by weight (C) Photopolymerization initiator" IRGACURE 184 "3 parts by weight Above (A), (B) And (C) were mixed to obtain an ultraviolet curable resin composition.

An optical disk substrate was manufactured in the same manner as in Example 1 except that the obtained ultraviolet-curable resin composition was used, a recording film was provided in the same manner as in Example 1, and then microscopic observation was performed. As a result, no wrinkles or cracks were found. Moreover, after leaving it in high temperature and high humidity (80 ° C., 85% RH) for 1,000 hours, the result of microscopic observation showed that
No wrinkles, cracks, etc. were observed, and no influence on the recording film was observed.

Example 3 (A) 29 parts by weight of urethane acrylate composed of (A) 2-hydroxypropyl acrylate (HPA) and hexamethylene diisocyanate (HDI) (B) N-vinyl-2-pyrrolidone (Toa Synthetic Chemical Industry Co., Ltd. Made: trade name "M-150") 15 parts by weight neopentyl glycol modified trimethylolpropane diacrylate (Nippon Kayaku Co., Ltd .: trade name "R-604") 30 parts by weight neopentyl glycol diacrylate (Nippon Kayaku Co., Ltd.) (Product name: “NPGDA”) 23 parts by weight (C) Photopolymerization initiator “Irgacure 184” 3 parts by weight The above (A), (B) and (C) were mixed to obtain an ultraviolet curable resin composition. .

An optical disk substrate was manufactured in the same manner as in Example 1 except that the obtained ultraviolet-curable resin composition was used, and a recording film was provided in the same manner as in Example 1, and then microscopic observation was performed. As a result, no wrinkles or cracks were found. Moreover, after leaving it in high temperature and high humidity (80 ° C., 85% RH) for 1,000 hours, the result of microscopic observation showed that
No wrinkles, cracks, etc. were observed, and no influence on the recording film was observed.

Comparative Example 1 (A) Urethane acrylate consisting of 2-hydroxypropyl acrylate (HPA) and hexamethylene diisocyanate (HDI) 35 parts by weight (B) Phenol EO-modified (n = 2) acrylate (Toagosei Kagaku) Kogyo Co., Ltd .: trade name "M-101") 40 parts by weight neopentyl glycol diacrylate (Nippon Kayaku Co .: trade name "NPGDA") 22 parts by weight (C) Photopolymerization initiator "Irgacure 184" 3 parts by weight The above (A), (B) and (C) were mixed to obtain an ultraviolet curable resin composition.

An optical disk substrate was manufactured in the same manner as in Example 1 except that the obtained ultraviolet-curable resin composition was used, and a recording film was provided in the same manner as in Example 1, and then observed under a microscope. As a result, wrinkles were found on the inner and outer mirror portions on the substrate. In high temperature and high humidity (80 ℃, 8
After being left at 5% RH) for 400 hours, microscopic observation revealed that wrinkle growth, cracking, and corrosion of the recording film were observed.

Comparative Example 2 (A) Urethane acrylate consisting of 2-hydroxypropyl acrylate (HPA) and hexamethylene diisocyanate (HDI) 34 parts by weight (B) Nonylphenol EO-modified (n = 1) acrylate (Toagosei Kagaku) Kogyo Co., Ltd .: trade name “M-111”) 37 parts by weight neopentyl glycol diacrylate (Nippon Kayaku Co .: trade name “NPGDA”) 26 parts by weight (C) Photopolymerization initiator “Irgacure 184” 3 parts by weight The above (A), (B) and (C) were mixed to obtain an ultraviolet curable resin composition.

An optical disk substrate was manufactured in the same manner as in Example 1 except that the obtained ultraviolet-curable resin composition was used, and a recording film was provided in the same manner as in Example 1, and then microscopic observation was performed. As a result, wrinkles were found on the inner and outer mirror portions on the substrate. In high temperature and high humidity (80 ℃, 8
After being left at 5% RH) for 400 hours, microscopic observation revealed that wrinkle growth, cracking, and corrosion of the recording film were observed.

Table 1 shows the glass transition temperatures of the UV-curable resin compositions obtained by mixing the monofunctional acrylates used in each example and each comparative example with the glass transition temperature at the time of homopolymerization.

The glass transition temperature was measured with a dynamic viscoelasticity measuring device at a frequency of 1 Hz and a heating rate of 4 ° C./min.

[0044]

[Table 1]

[0045]

EFFECTS OF THE INVENTION By using the ultraviolet-curable resin composition for optical disks of the present invention, as compared with the prior art, (1) no wrinkles or cracks are generated in the high temperature and high humidity test, (2) white turbidity, yellowing It is possible to provide an optical disk substrate which does not cause (3) does not attack the recording film and (4) has good adhesion to the support.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08F 299/06 MRX 7442-4J

Claims (3)

[Claims] 1. A glass transition temperature (Tg) during homopolymerization of (1) urethane acrylate and (2) is 150 to 180 ° C.
An ultraviolet-curable resin composition for an optical disc, which contains a monofunctional vinyl compound, (3) a polyfunctional (meth) acrylate, and (4) a photopolymerization initiator in the range of 1. 2. An optical disk substrate having a cured layer made of the ultraviolet curable resin composition according to claim 1. 3. The optical disk substrate according to claim 2, wherein the hardened layer has a preformat signal and a guide groove.