JP2959050B2 - Photocurable resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photocurable resin composition for modifying the surface of an optical disk substrate, and more particularly, to an optical disk substrate such as a digital audio disk, an optical disk or a magneto-optical disk. The present invention relates to a photocurable resin composition for a surface protective coat having a low surface resistance, which has improved scratch resistance on the surface and little adhesion of dust and dirt.

[Prior Art] Polycarbonate is used as a substrate of a digital audio disk, an optical disk, and a magneto-optical disk for recording and reproducing information on an optical recording layer comprising a recording layer or a light reflecting layer, and reproducing information formed on the information recording layer. Synthetic resin substrates such as polymethyl methacrylate and amorphous polyolefin are used.

These resins are optically homogeneous, have high transparency, and have excellent moldability and mechanical strength.However, they have low surface hardness and are easily scratched on the substrate surface. However, there is a disadvantage that the reading sensitivity of the information recorded in the information storage device is lowered and an error easily occurs.

In addition, the synthetic resin substrate is easily charged when used, and easily adsorbs dust and dust on the surface, and thus has the disadvantage that the signal reading sensitivity is lowered and an error occurs.

In order to solve such problems, a surface protective coating agent for protecting a substrate by applying a resin composition curable by light or heat on a synthetic resin substrate by a dipping or spinner method and curing the resin composition has been developed. I have.

However, the conventional protective coat for protecting the substrate cannot solve the charging property of the substrate, and unresolved problems such as a decrease in reading sensitivity due to adhesion of dust and dust to the substrate due to charging and the occurrence of errors. ing.

As a method of preventing the chargeability of the substrate, a method of blending an antistatic agent in a protective coating agent is also conceivable. However, in this method, since the antistatic agent bleeds on the surface of the disk, digital audio disks, optical disks, It cannot be applied to optical disks such as magneto-optical disks.

As described above, up to the present, a photocurable resin composition having good antistatic ability and not causing bleeding has not been found.

[Problems to be Solved by the Invention] In view of the above situation, the present inventors consider that dust on an optical disc,
The present invention relates to a photocurable resin composition having good antistatic ability for preventing dust from adhering and causing no bleeding, an optical recording medium using the same as a protective coating agent, and a method for producing the same.

[Means for Solving the Problems] The present inventors have conducted intensive studies in order to solve the above problems. As a result, the photocurable resin composition having a specific structure and containing a polymer having an acryl and / or methacryl group is effective as a protective coating agent on the surface of an optical disc substrate, and has a scratch resistance on the substrate surface. , A low surface resistance, and no bleeding.

That is, the present invention provides the following general formula (1) (However, R ₁ , R ₂ and R ₃ are each H or CH ₃ , and n is 1
An integer of 整数 14, x is 0 to 0.99, and y is a positive number of 0.01 to 1) as a protective coating agent for an optical disk such as a digital audio disk, an optical disk, or a magneto-optical disk. An object of the present invention is to provide a photocurable resin composition having excellent scratch resistance, a low surface resistance value, and no bleeding.

The polymer represented by the general formula (1) in the present invention is a polyethylene glycol monoacrylate or /
And methacrylic acid ester polymers and acrylic acid halides and / or methacrylic acid halides or from acrylic acid and / or methacrylic acid.

In the present invention, the reaction rate with acrylic acid halide and / or methacrylic acid halide or the reaction rate with acrylic acid and / or methacrylic acid is from 1% to 10%.
Any positive number of 0%, preferably 5% to 100%.

If the reaction rate is 1% or less, the reactivity due to light is reduced, and the required physical properties are not exhibited.

The photocurable resin composition in the present invention may be the above polymer alone, or may be a mixture containing a polyfunctional acrylic and / or methacrylic acid ester or a crosslinkable oligomer that is cured by light. It is optional as long as the physical properties after curing are not reduced. In consideration of the viscosity and the like of the obtained composition, it is preferable to use a mixture from the viewpoint of easy handling.

The polyfunctional acrylic and / or methacrylic acid ester in the present invention is a bifunctional or trifunctional or more functional acrylic and / or methacrylic acid (hereinafter referred to as “(meth) acrylic acid”) ester.
More than functional (meth) acrylates are preferred.

Representative examples of the trifunctional or higher functional (meth) acrylate used in the present invention include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol hexa. (Meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate , Isocyanuric acid ethylene oxide / ε-caprolactone modified tri (meth) acrylate, with hexamethylene diisocyanate and glycerin It can be mentioned diacrylate dimethacrylate things.

Representative examples of the bifunctional (meth) acrylate used in the present invention include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and ethylene oxide-modified bisphenol A (meth). ) Acrylate, polyethylene oxide-modified (meth) acrylate, trimethylolpropane (meth) acrylate benzoate, 3- (meth)
Acryloyloxyglycerin mono (meth) acrylate, dipropylene glycol di (meth) acrylate and the like can be mentioned.

The polyfunctional (meth) acrylate used in the present invention is preferably used in an amount of at least 15% by weight or more.

When the amount is less than 15% by weight, the degree of crosslinking of the film cured by ultraviolet rays is insufficient, and not only the initial physical properties such as the adhesive strength, but also the adhesive strength under a moist heat atmosphere are significantly reduced.

This polyfunctional (meth) acrylate may be used alone or in combination of two or more. The following can be illustrated as typical examples of the crosslinkable oligomer used in the present invention.

Examples thereof include polyester (meth) acrylate, polyether (meth) acrylate, polyurethane (meth) acrylate, epoxy (meth) acrylate, and silicon (meth) acrylate.

The following can be further mentioned as specific examples of these.

Polybutylene adipate diacrylate, polypropylene glycol diacrylate, polyurethane diacrylate (composed of polyester glycol and isocyanate), spiroglycol urethane diacrylate, bisphenol A type epoxy acrylate, bisphenol F type epoxy acrylate, phenol novolak type epoxy acrylate, cresol novolak Epoxy methacrylate, polydimethylsiloxane dimethacrylate and the like.

These acrylates are useful as practically useful crosslinkable oligomers.In addition, resins such as unsaturated polyesters and polyamides having active groups in side chains, such as polyamides, polyurethanes, polyesters, polysulfones, polyethersulfones, and polyphenylene oxides can be used. Acrylic acid ester modified ones can also be used satisfactorily.

Although the molecular weight of the crosslinkable oligomer used in the present invention can be used over a considerably wide range, preferably,
200 to 50000.

It is desirable to use at least 15% by weight or more of the crosslinkable oligomer of the present invention.

This crosslinkable oligomer may be used alone or in combination of two or more.

Although the photocurable resin composition of the present invention contains a photoinitiator, examples of the photoinitiator include ketals such as benzyldimethyl ketal, benzoin methyl ether,
Benzoins such as benzoin ethyl ether, benzoin-1-propyl ether, benzoin, α-methylbenzoin, anthraquinones such as 9,10-anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone and 2-ethylanthraquinone, benzophenone, p −
Chlorobenzophenone, p-dimethylaminobenzophenone, p, p'-tetramethyldiaminobenzophenone,
Benzophenones such as p, p'-tetraethyldiaminobenzophenone, acetophenones such as 2-hydroxy-2-methylpropiophenone and 1-hydroxycyclohexylphenyl ketone, suberones such as dibenzosuberone, diphenylsulfide, thioxanthone, Sulfur-containing compounds such as methyl-1- [4- (methylthio) phenyl] -2-morphylinopropanone-1 and dyes such as methylene blue, eosin, and fluorescein, and the like, alone or in combination of two or more. Used.

In the present invention, the compounding ratio of the photoinitiator is 0.1 to 20% by weight based on the whole resin composition, preferably 0.5 to 20% by weight.
~ 20% by weight.

The resin composition of the present invention contains hydroquinone monomethyl ether, t-butylcatechol, p-benzoquinone, 2,5,5 to prevent thermal polymerization during production and dark reaction during storage.
It is desirable to add a known thermal polymerization inhibitor such as -t-butylhydroquinone and phenothiazine.

Further, in the resin composition of the present invention, various additives such as an antifoaming agent and a leveling agent may be added in addition to the above additives as long as the physical properties of the cured product are not deteriorated.

The organic protective layer obtained by curing the resin composition as described above is provided on the optical disk substrate. To provide such a protective layer on the optical disk substrate, the following method may be used.

That is, first, the above resin composition is applied to a substrate using a coating method such as a brush coating method, a spray method, a dipping method, a bar coating method, a roll coater method, and a spin coater method, and a coating film is provided. What is necessary is just to harden this coating film.

The coating thickness is 0.5 to 500 μm, preferably 1 to 50 μm.

The method of curing the coating film can be obtained by irradiating light such as ultraviolet light under arbitrary conditions.

At this time, in order to improve the curability of the resin composition, nitrogen,
There is no problem even if curing is performed in an atmosphere of an inert gas such as argon.

The material and the configuration of the optical disc substrate are not limited at all.

[Effects of the Invention] The photocurable resin composition of the present invention obtained in this manner, which is photocured under predetermined conditions, has improved scratch resistance on the substrate surface, exhibits a low surface resistance, and has bleed. It has the characteristic of no occurrence of blemishes, and is extremely excellent as a protective coating agent for the surface of optical disk substrates such as digital audio disks, optical disks, and magneto-optical disks.

[Examples] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The physical properties obtained in the examples were measured by the following test methods.

(1) Accelerated durability test: In an environment with a temperature of 80 ° C and a humidity of 80% RH
Left for 2000 hours.

(2) Hardness: Measured with a pencil hardness tester according to JIS-KJ6911. (3) Microscopic observation: Observation was performed using a polarizing microscope.
When the bleeding of the surface was observed, it was evaluated as x, and when it was not observed, it was evaluated as ○.

(4) Surface resistance: 23 ° C, 50% using a surface resistance measuring device
The surface resistance was measured under the condition of RH.

Example 1 96.4 g of nonaethylene glycol monomethacrylate, 400 ml of tetrahydrofuran and 0.32 g of azoisobutyronitrile were added to a 1000 ml separable flask, and after degassing, the atmosphere was replaced with argon and the reaction was carried out at 55 ° C for 5 hours with stirring. After the reaction,
The reaction solution was poured into 2000 ml of hexane to obtain a product, which was then redissolved in 500 ml of tetrahydrofuran, and poured into 2000 ml of hexane to purify and recover the product. When the obtained polymer was dried under vacuum at 40 ° C., the yield was
It was 74 g.

The resulting polymer had an infrared absorption spectrum, ¹ H and ¹³
From the C-NMR spectrum, it was confirmed that nonaethylene glycol monomethacrylate was an oligomer obtained by radical polymerization.

Example 2 Under an argon atmosphere, 48.5 g of the polymer obtained in Example 1 was placed in a 500 ml separable flask in 200 ml of tetrahydrofuran.
Was added thereto, and 4.5 g of acrylic acid chloride was added at 0 ° C., followed by a reaction at room temperature for 2 hours with stirring.

After the completion of the reaction, 50 ml of water was added and the mixture was filtered, and the reaction product was poured into 1000 ml of hexane to recover a product.

The product was dried at 40 ° C. under vacuum and the yield was 42 g.
Met.

From the infrared absorption spectrum, ¹ H-NMR spectrum, and ¹³ C-NMR spectrum of the product, it was found that acrylation had progressed by 45%.

Example 3 A reaction was carried out in the same manner as in Example 2 except that 9.1 g of acrylic acid chloride was added.

After the completion of the reaction, 50 ml of water was added and the mixture was filtered, and the reaction product was poured into 1000 ml of hexane to recover a product.

The product was dried at 40 ° C under vacuum, yielding 45g
Met.

The product was found to be 95% acrylated from the infrared absorption spectrum, ¹ H and ¹³ C-NMR spectrum.

Example 4 50% of the polymer obtained in Example 2, 30% of pentaerythritol triacrylate and 20% of 1,6-hexanediol diacrylate were blended, and the total amount was adjusted to 100 g. -Hydroxycyclohexyl phenyl ketone was added to form a photopolymerizable resin composition.

This resin composition was spin-coated on a 5.25 inch polycarbonate magneto-optical disk at 3000 rpm for 5 seconds to form a coating film.

Then, the disk was exposed to ultraviolet light for 10 seconds using a high-pressure mercury lamp with an output of 120 W. The amount of ultraviolet light at this time is the wavelength
The integrated illuminance at 365 nm was 870 mJ.

An accelerated durability test was performed using the disk having the protective coating layer thus cured, and surface resistance, disk surface microscopic observation, and measurement of pencil hardness were performed. Table 1 shows the results
Shown in

Example 5 Example 4 was repeated except that the polymer synthesized in Example 3 was used.
In the same manner as described above, a resin composition was blended, spin-coated, and exposed to ultraviolet light.

Thereafter, the same test as in Example 4 was performed. Table 1 shows the results
Shown in

Comparative Example Bisphenol A-epoxy acrylate 40%, pentaerythritol triacrylate 30%, ethylene glycol diacrylate 20%, 1,6-hexanediol diacrylate 10 as base resin of surface protective coating agent
%, Adjusted to a total amount of 100 g, and 1% of 5%
After adding -hydroxycyclohexyl phenyl ketone to form a photopolymerizable resin composition, spin coating and ultraviolet exposure were performed in the same manner as in Example 4. Thereafter, the same test as in Example 4 was performed.

 Table 1 shows the results.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G11B 7/24 C08F 299/00-299/08 C08F 290/00-290/14 C08F 8/00-8 / 50 C08F 2/00-2/60

Claims (1)

(57) [Claims] 1. The following general formula (1) (However, R ₁ , R ₂ and R ₃ are each H or CH ₃ , and n is 1
An integer of 1414, x is 0 to 0.99, and y is a positive number of 0.01 to 1). An organic protective layer obtained by photocuring a photocurable resin composition containing a compound represented by An optical recording medium characterized by the following.