JPH09194546A - Curing resin composition and low hygroscopic optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curing resin composition which is suitable for obtaining an optical material of reduced warpage and deformation caused by moisture absorption because its low moisture absorption, and an optical material of low moisture absorption. SOLUTION: This curing resin composition comprises (A) 25-70 pts.wt. of a polybutadiene main chain skeleton oligomer bearing 2 or more (meth)acryloyl groups every molecule, (B) 20-60 pts.wt. of a monofunctional (meth)acrylate, (C) 0-40 pts.wt. of 3 or more functional (meth)acrylate and (D) 0.01-5 pts.wt., per 100 pts.wt. of the total of components A+B+C, of a radical polymerization initiator. This resin composition is cured in a prescribed shape to give an optical material of low moisture absorption.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a curable resin composition and a low hygroscopic optical member suitable for obtaining an optical member having low hygroscopicity.

[0002]

2. Description of the Related Art Conventionally, resins based on radical polymerization have been used for optical members such as optical disk substrates and composite aspherical lenses. However, when the optical members are made of a radically polymerizable resin composition. However, the occurrence of warpage and deformation of the optical member due to moisture absorption has been a problem. Particularly in the optical disk substrate, if the warpage due to moisture absorption is large, it becomes impossible to read a signal, and also in the complex aspherical lens, the deformation due to moisture absorption causes a decrease in accuracy and optical distortion.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a curable resin composition and a low hygroscopic optical member suitable for obtaining an optical member having low hygroscopicity and less warpage and deformation due to moisture absorption. .

[0004]

The present invention provides the following (A),
25-70 parts by weight of a polybutadiene main chain skeleton oligomer having two or more (meth) acryloyl groups in one molecule, (A) a curable resin composition comprising components (B), (C) and (D). ) 20 to 60 parts by weight of monofunctional (meth) acrylate (C) 0 to 3 or more polyfunctional (meth) acrylate
40 parts by weight (D) at least one radical polymerization initiator (A),
The total amount of components (B) and (C) is 100 parts by weight, and
01-5 parts by weight

Also, there is provided a low hygroscopic optical member obtained by curing the curable resin composition into a predetermined shape.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A polybutadiene main chain skeleton oligomer having two or more (meth) acryloyl groups in one molecule of the component (A) in the resin composition of the present invention (hereinafter,
Polybutadiene oligomer) is a homopolymer of butadiene or a copolymer mainly composed of butadiene, in which two or more (meth) acryloyl groups are introduced at the molecular end and / or side chain, and it is possible to obtain a cured product with low hygroscopicity. It is an essential ingredient in.

The polybutadiene oligomer as the component (A) is, for example, Nisso-PB TE-produced by Nippon Soda Co., Ltd.
Although it is available as 2000, a homopolymer or copolymer of butadiene having a hydroxyl group, a carboxyl group or a glycidyl group at a molecular end and / or a side chain is used for the synthesis of a polybutadiene oligomer, and in the case of using a hydroxyl group-containing butadiene polymer, After the urethanization reaction with two or more isocyanate group-containing isocyanate compounds, the remaining isocyanate group and hydroxyl group-containing (meth)
A method of synthesizing by reacting with an acrylate, a method of synthesizing by an epoxy ring-opening reaction in the case of using a carboxyl group-containing butadiene polymer, and a method of synthesizing in the case of using a glycidyl group-containing butadiene polymer (meth) acrylic acid or aliphatic or aromatic The method of synthesizing by an epoxy ring-opening reaction of the acid anhydride of (1) with an adduct of (meth) acrylic acid is used.

To give more specific examples of the synthesis of polybutadiene oligomer, aliphatic diisocyanate compounds such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, diphenylmethane diisocyanate, etc. Aromatic diisocyanate compound, isophorone diisocyanate, diisocyanate compound such as alicyclic diisocyanate compound such as dicyclohexylmethane diisocyanate, and 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) By the urethanization reaction with hydroxyl group-containing (meth) acrylates such as acrylates, Generates sulfonates, further the product with, for example Nippon Soda Co. Nisso-PB, by reacting a hydroxyl group-containing butadiene polymer, available as G-Series synthesize polybutadiene oligomer.

The polybutadiene oligomer as the component (A) is used in an amount of 25 to 70 parts by weight, preferably 30 to 60 parts by weight. If it is less than 25 parts by weight, the toughness of the cured product will decrease, and 70 parts by weight will be used. When it exceeds the above range, the viscosity of the resin liquid increases and bubbles easily enter, so that the injection workability deteriorates.

The monofunctional (meth) acrylate as the component (B) plays a role as a reactive diluent, and specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate and n-butyl (meth) acrylate. , I-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and other aliphatic (meth) acrylates, phenyl (meth) acrylate , Benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypropyl (meth) acrylate and other aromatic (meth) acrylates, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, Cyclopentenyloxyethyl (meth) acrylate, tricyclo [5 · 2 · 1 · 0
^Examples thereof include alicyclic (meth) acrylates such as ^2,6 ] decanyl (meth) acrylate.

In order to exhibit a lower hygroscopicity, the monofunctional (meth) acrylate as the component (B) is an aromatic (meth) acrylate and an alicyclic (meth) acrylate as exemplified above. More preferably, it is at least one selected from the group

The amount of the monofunctional (meth) acrylate used as the component (B) is 20 to 60 parts by weight, preferably 30 to 50.
If the amount is less than 20 parts by weight, the viscosity of the resin liquid becomes high, bubbles are likely to enter, and the workability of injection is deteriorated.
If it exceeds the amount by weight, the toughness of the cured product decreases.

Trifunctional or higher polyfunctional (meta) component (C)
Acrylate is used for the purpose of improving curability and physical properties of a cured product such as heat resistance, and specific examples include trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth). Acrylate, tris (meth) acryloxyethyl isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and the like can be mentioned.

The amount of the polyfunctional (meth) acrylate used as the component (C) is 0 to 40 parts by weight, preferably 10 to 30 parts by weight. And the like tend to remain, and the cured product is likely to crack when cured.

The radical polymerization initiator of the component (D) is one which produces radical species by heat or light to initiate polymerization. Specific examples of the thermal polymerization initiator include benzoyl peroxide, diisopropyl peroxypercarbonate, t
Examples include organic peroxides such as -butyl peroxyisobutyrate, t-butyl peroxy-2-ethylhexanoate, cumene hydroperoxide, and azobisisobutyronitrile.

Specific examples of the photopolymerization initiator include 2
-Hydroxy-2-methyl-1-phenylpropane-1
-One, 1-hydroxycyclohexyl phenyl ketone, methylphenyl glyoxylate, acetophenone, benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-methyl [-4- (methylthio)
Phenyl-] morpholino-1-propane, benzyl,
Benzoin methyl ether, benzoin ethyl ether, 2-chlorothioxanthone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl- Examples thereof include phosphine oxide.

The radical polymerization initiator of the component (D) is required to be at least one selected from the group of thermal polymerization initiators and photopolymerization initiators exemplified above. From the viewpoint of properties, a photopolymerization initiator is preferable.

The amount of the radical polymerization initiator as the component (D) used is 10 in total of the components (A), (B) and (C).
0.01 to 5 parts by weight relative to 0 parts by weight, 0.01
If it is less than 5 parts by weight, the curability will be insufficient, and if it exceeds 5 parts by weight, the curability will not be significantly improved and the economy will be impaired.

The resin composition of the present invention may contain other copolymerizable compounds and additives within a range that does not impair the low hygroscopic effect of the present invention. A silane coupling agent such as γ-methacryloxypropyltrimethoxysilane or vinyltriethoxysilane may be blended for the purpose of improving the properties, and a thermal oxidation stabilizer, an ultraviolet absorber, a bluing agent, a foaming agent, etc. Additives can also be added.

The resin composition of the present invention is curable by heat or light, and by curing the resin composition of the present invention into a predetermined shape, it becomes an optical member such as an optical disk substrate or a complex aspherical lens. The obtained optical member has low hygroscopicity and is useful as a low hygroscopic optical member.

When a thermal polymerization initiator is used for curing the resin composition of the present invention, after injecting the resin composition into a mold,
Method of heating and curing in a hot air drying oven, when using a photopolymerization initiator, the resin composition is injected into a light-transmitting mold such as a glass mold and irradiated with active energy rays such as ultraviolet rays. A method of polymerizing and curing is used. It is also possible to use a method in which a thermal polymerization initiator and a photopolymerization initiator are used in combination, and after irradiation with ultraviolet rays or the like for polymerization and curing, further heating for polymerization and curing.

When polymerizing and curing by irradiation of ultraviolet rays,
Preferably, ultraviolet rays having a wavelength of 2000 to 8000 angstroms are used, and as the light source, a chemical lamp, a xenon lamp, a low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp or the like is used. In addition to the method of polymerizing and curing by irradiation with ultraviolet rays, a method of polymerizing and curing by irradiation with X-rays, electron beams, visible rays or the like can also be used.

The optical member obtained by curing the resin composition of the present invention into a predetermined shape is an optical member having low hygroscopicity and less warpage and deformation due to moisture absorption.

[0024]

The present invention will be described below in more detail with reference to examples. The abbreviations for monomers and the abbreviations in the table are as follows.

PB01: polybutadiene oligomer (butadiene polymer Nisso-P manufactured by Nippon Soda Co., Ltd.)
Reaction product of BC-1000 and glycidyl methacrylate) PB02: polybutadiene oligomer Nisso-PBTE-2000 BzMA manufactured by Nippon Soda Co., Ltd .: benzyl methacrylate IBXMA: isobornyl methacrylate TMPTA: trimethylolpropane triacrylate UMA1: tolylene diisocyanate Urethane oligomer with hydroxypropyl methacrylate EMA1: bisphenol A diglycidyl ether dimethacrylate PI1: 2-hydroxy-2-methyl-1-phenylpropan-1-one PI2: 1-hydroxycyclohexylphenyl ketone TI1: t-butylperoxyiso Butyrate

(Example 1) <Synthesis of polybutadiene oligomer (PB01)> A butadiene polymer having a carboxyl group at the molecular end (Niso-PB C-1000, Mw manufactured by Nippon Soda Co., Ltd.)
= 1350 ± 150) 1300 parts by weight, glycidyl methacrylate 284 parts by weight, dimethylaminomethyl methacrylate 8 parts by weight, hydroquinone monomethyl ether 0.8 parts by weight at 70 ° C. for 3 hours, then 11
It was synthesized by reacting at 0 ° C. for 5 hours.

The resulting polybutadiene oligomer (PB
01) 50 parts by weight, benzyl methacrylate 25 parts by weight, trimethylolpropane triacrylate 25 parts by weight, 2-hydroxy-2-methyl- as a photopolymerization initiator
0.1 part by weight of 1-phenylpropan-1-one and 0.1 part by weight of 1-hydroxycyclohexyl phenyl ketone were blended to obtain a resin composition.

This resin composition was poured between glass plates with a spacer having a thickness of 1 mm interposed therebetween, the periphery was sealed with tape so that the liquid did not leak, and ultraviolet rays were irradiated with a high pressure mercury lamp at 1
After irradiation with 000 mJ / cm ² for polymerization and curing, the glass plate was removed to obtain a cured product. The obtained cured product is cut into 3 cm square pieces, and they are placed in a thermo-hygrostat at 60 ° C. and 90% RH for 200 hours.
When a moisture absorption test was performed for a period of time and the moisture absorption rate was calculated from the weight change before and after the test, the moisture absorption rate was 0.39%. The evaluation results of the obtained cured product are shown in Table 1.

(Example 2) In Example 1, 0.5 parts by weight of t-butylperoxyisobutyrate was used as a thermal polymerization initiator instead of the photopolymerization initiator, and the reaction was carried out at 80 ° C for 10 hours and then at 150 ° C. A cured product was obtained in the same manner as in Example 1 except that the polymer was cured by heating for 1 hour. The moisture absorption rate obtained by the same moisture absorption test as in Example 1 of the obtained cured product was 0.3.
It was 9%. The evaluation results of the obtained cured product are shown in Table 1.
It was shown to.

(Examples 3 to 4 and Comparative Examples 1 to 7) The composition of the resin composition was changed as shown in Table 1, and in the case of photopolymerization, a metal halide lamp was used and thermal polymerization was performed in the same manner as in Example 1. In that case, a cured product was obtained in the same manner as in Example 2.
The moisture absorption rate of the obtained cured product and the evaluation results are shown in Table 1.
As the polybutadiene oligomer (PB02), Nisso-PB TE-200 manufactured by Nippon Soda Co., Ltd. is used.
0 was used.

[0031]

[Table 1]

As shown in Table 1, the cured products obtained in Examples 1 to 4 had low hygroscopicity, were tough, and had good injection workability. However, as shown in Comparative Examples 1 and 2, (A)
When a urethane oligomer or an epoxy oligomer is used as a component, the moisture absorption rate of the cured product does not exceed 1% and does not have low hygroscopicity, and the amount of the component (A) exceeds 70 parts by weight as shown in Comparative Example 3. As shown in Comparative Example 6, if the amount of the component (B) is less than 20 parts by weight, the viscosity of the resin composition becomes too high, and bubbles tend to enter, resulting in a decrease in injection work. Comparative Example 4
When the amount of the component (A) is less than 25 parts by weight as shown in Fig. 4 or the amount of the component (B) exceeds 60 parts by weight as shown in Comparative Example 5, the cured product becomes brittle and the toughness is insufficient, resulting in a cured product. The cured product becomes liable to crack during demolding. Further, as shown in Comparative Example 7, when the amount of the component (C) exceeds 40 parts by weight, the curing shrinkage becomes large, so that the cured product is easily cracked during curing.

[0033]

According to the curable resin composition of the present invention, a tough cured product having good workability and low hygroscopicity can be obtained, which is suitable for obtaining an optical member. The cured product obtained from the curable resin composition of, warps due to moisture absorption,
Therefore, it is extremely useful as a low hygroscopic optical member for obtaining a highly accurate optical member with little deformation.

Claims (4)

[Claims] 1. The following (A), (B), (C) and (D)
A curable resin composition comprising components. (A) 25 to 70 parts by weight of polybutadiene main chain skeleton oligomer having two or more (meth) acryloyl groups in one molecule (B) 20 to 60 parts by weight of monofunctional (meth) acrylate (C) Trifunctional or more Polyfunctional (meth) acrylate is 0
40 parts by weight (D) at least one radical polymerization initiator (A),
The total amount of components (B) and (C) is 100 parts by weight, and
01-5 parts by weight 2. The monofunctional (meth) acrylate as the component (B) is an aromatic (meth) acrylate or an alicyclic (meth) acrylate.
The curable resin composition according to claim 1, which is at least one selected from the group of acrylates. 3. The curable resin composition according to claim 1, wherein the radical polymerization initiator of the component (D) is a photopolymerization initiator. 4. A low hygroscopic optical member obtained by curing the curable resin composition according to claim 1 into a predetermined shape.