Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-02-11
2001-09-11
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S172000, C522S181000, C522S182000, C522S103000, C427S508000, C427S516000, C427S517000, C428S413000
Reexamination Certificate
active
06288136
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a radiation curable resin composition which can be rapidly cured by radiation exposure, and, especially to a radiation curable resin composition for cast polymerization which is suitable not only for molded articles used for manufacturing optical parts such as lenses, optical disks, prisms, glass sheets, and the like, but also for surface coating materials which are applied to plastic film substrate materials used as optical materials such as substrates for liquid crystal display devices and the like.
DESCRIPTION OF RELATED ART
There are methods proposed for manufacturing plastic lenses or the like by irradiating a radiation curable resin composition with UV-rays from a mercury lamp as activated energy rays (see Japanese Patent Applications Laid-open No. 194401/1986 and No. 207632/1989). These methods have an advantage whereby the resin composition can be cured in a short period of time by irradiation with UV-rays. However, the transparency and hue of lenses produced by curing using UV-ray radiation are inferior to those of polymers such as polymethyl methacrylate, polycarbonate, diethylene glycol bisaryl carbonate, or the like. Also, there is a problem of coloring by ultraviolet radiation exposure and the like after molding. In addition, in a cast molding process for a UV-ray curable resin, a curing stress at the time of curing tends to remain in a molded article, which causes camber deformation and shrinkage, leading to a reduction in dimensional accuracy.
Radiation curable compositions for cast polymerization are known from EP-A-313665 and WO-A-9321010. These applications disclose compositions based on an acrylate oligomer (resp. an urethane (meth)acrylate oligomer and an epoxy (meth)acrylate oligomer), an acrylate monomer and a photoinitiator.
Epoxy (meth)acrrlate oligomers having a (poly)alkylene oxide terminated aromatic backbone are disclosed in EP-A-780712. These oligomers are used in peelable coating/matrix materials for optical fibers.
Japanese Patent Application Laid-open No. 174910/1995 discloses a prism sheet used to improve the frontal brightness of a back light unit used in a liquid crystal display apparatus. As a method for manufacturing this prism sheet, which is a molded article molded into a specific form using a transparent material with a specific refractive index, a monobloc molding method using transparent glass with a refractive index of a specific range and a method of forming a prism-shaped article using a UV-ray curable resin composition are disclosed. Furthermore, an active ray curable resin composition for cast polymerization, which is depth curable and is featured by a small optical strain in the cured product, is disclosed in Japanese Patent Application Laid-open No. 65111/1989.
Plastic materials represented by these UV-ray curable resins, however, are limited in use in the fields which require a thermal resistance as described in the above Patent Application Laid-open No. 65111/1989. Specifically, such a plastic material has a fatal drawback that, when a lens sheet represented by a prism sheet obtained using the conventional UV-ray curable resin is allowed to stand at a high temperature, a part of the lens sheet fuses and erodes to leave an adhesion scar on the surface of the back light, exerting an adverse influence on the optical properties.
Especially in cast polymerization, because a resin composition is polymerized by the radioactive rays transmitted from a mold made of glass or the like and from materials such as a plastic film or the like, the bulk of the rays of a short wave length is absorbed by shielding materials. The resin composition cannot acquire sufficient energy (absorption energy) to cure itself, whereby not only the curability and productivity are reduced, but also unreacted substances remain in the cured product, resulting in reductions in surface hardness and thermal resistance, which are fatal problems.
PROBLEMS TO BE SOLVED BY THE INVENTION
The present invention has been undertaken to solve the above conventional problems and has an object to provide a radiation curable resin composition which has excellent transparency, small light-coloring resistance, high dimensional accuracy, excellent curability, high surface hardness, and high thermal resistance so that it can produce at high yield molded articles, which never stick to or erode an adjacent substrate or the like in a high temperature condition.
MEANS FOR THE SOLUTION OF THE PROBLEMS
The present inventors have conducted earnest studies in view of this situation, and, as a result, discovered the following radiation curable resin composition to complete the present invention.
Accordingly, the present invention provides a radiation curable resin composition for cast polymerization, comprising:
(A) 20-94.9% by weight of a (meth)acryloyl group-containing compound (hereinafter called “component (A)”) represented by the following general formula (1):
wherein R
1
represents a hydrogen atom or a methyl group, R
2
represents an alkylene group or a hydroxyalkylene group having 2-6 carbon atoms, R
3
represents a divalent organic group, n denotes an integer from 0 to 6, m denotes an integer from 1 to 10, and L denotes an integer from 0 or 1;
(B) 5-79.9% by weight of a (meth)acryloyl group-containing compound (hereinafter called “component (B)”) represented by the following general formula (2):
wherein R
4
represents a hydrogen atom or a methyl group, R
5
represents an alkylene group having 2-6 carbon atoms, and p denotes an integer from 1 to 16; and
(C) 0.1 to 10% by weight of a radiation active initiator (hereinafter called “component (C)”) having molar absorption coefficients of 100 L·mol
−1
·cm
−1
or more at a wave length of 360 nm and of 100 L·mol
−1
cm
−1
or less at a wave length of 450 nm.
The present invention will now be explained in detail by way of an embodiment.
In (meth)acryloyl group-containing compounds used as component (A) of the present invention, as the alkylene group or the hydroxyalkylene group having 2-6 carbon atoms, which is represented by R
2
in the above formula (1), divalent organic groups represented by the following formulae (
3-1
) to (
3-11
) are exemplified:
—CH
2
CH
2
— (
3-1
)
—CH
2
CH
2
CH
2
— (
3-2
)
—CH
2
CH
2
CH
2
CH
2
— (3-4)
—CH
2
CH
2
CH
2
CH
2
CH
2
— (3-6)
—CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
— (3-8)
Among these, the organic groups represented by formulae (3-1), (3-3), and (3-11) are preferred.
In addition, as preferable organic groups represented by R
3
when L is 1 in the above general formula (1), organic groups represented by the following formulae (4-1) to (4-7) are exemplified:
Among these, the organic groups represented by formula (4-1) are particularly preferable. Also, compounds having a structural formula in which hydrogens of optional aromatic rings in general formula (1) are substituted with a bromine atom and a chlorine atom may be used.
Specific examples of the compounds represented by formula (1) include ethylene oxide addition bisphenol A (meth)acrylate, propylene oxide addition bisphenol A (meth)acrylate, bisphenol A diglycidyl ether epoxy acrylate prepared by an epoxy ring-opening reaction of bisphenol A diglycidyl ether and (meth)acrylic acid, bisphenol F diglycidyl ether epoxy acrylate prepared by an epoxy ring-opening reaction of bisphenol F diglycidyl ether and (meth)acrylic acid, and the like.
These compounds are commercially available under the trademarks, for example, of Viscoat 700, 540 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), Aronix M-210 (manufactured by Toagosei Co., Ltd.), NK Ester BPE-100, BPE-200, BPE-500, A-BPE-4 (manufactured by Shin-Nakamura Chemical Co., Ltd.), Light Ester BP-4EA, BP-4PA, BP-2PA, BP-2EA, Epoxy Ester 3002M, 3002A, 3000M, 3000A (manufactured by Kyoeisha Chemical Co., Ltd.), KAYARAD R-551, R-712 (manufactured by Nippon Kayaku Co., Ltd.), BPE-4, BPE-10, BR-42M (manufactured by Daiichi Kogyo Seiyaku Co., Lt
Takahashi Toshihiko
Ukachi Takashi
Ukon Masakatsu
DSM N.V.
McClendon Sanza L.
Pillsbury & Winthrop LLP
Seidleck James J.
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