Stock material or miscellaneous articles – Structurally defined web or sheet – Physical dimension specified
Reexamination Certificate
2001-01-12
2002-05-21
Beck, Shrive P. (Department: 1762)
Stock material or miscellaneous articles
Structurally defined web or sheet
Physical dimension specified
C428S336000, C351S166000, C427S164000, C427S372200, C427S384000
Reexamination Certificate
active
06391433
ABSTRACT:
This application is based on Japanese Laid-Open Patent Application No. 2000-002801, filed Jun. 12, 1998, and published Jan. 7, 2000, the entire contents of which are incorporated by reference.
FIELD OF THE INVENTION
The invention relates to a coating composition for optical parts, a thin film layer made of the coating composition and an optical part. In particular, it relates to a coating composition favorable for obtaining optical parts having good impact resistance, good adhesion between the substrate and the thin film layer, good scratch resistance and good antireflection capabilities, and also to a thin film layer made of the coating composition and an optical part including the coating composition.
BACKGROUND OF THE INVENTION
Recently, plastic materials have been used for optical parts in place of inorganic glass, especially for eyeglass lenses, because they are lightweight and have good dyeability and good impact resistance. In particular, a diethylene glycol bisallylcarbonate polymer (hereinafter referred to as CR-39) has been used, primarily for plastic lenses. However, it has a refractive index of 1.50, which is lower than that of inorganic glass. Although lenses made of CR-39 have relatively strong power, they are thick and do not generally have a good appearance. Various types of high-refractive-index, low-chromatic-aberration plastic lenses have also been tried, but they are also not free from problems.
Ordinary plastic lenses are poor in scratch resistance. It has been known to provide a silicone-based, hard coat layer on the substrate surface of plastic lenses to improve scratch resistance. In addition, the hard coat layer can be overcoated with an inorganic antireflection layer. The reflection layer can be applied, for example, by vacuum vapor deposition. The added antireflection layer provides the additional benefit of reducing surface reflection that could cause image flickering. In addition, an outer layer can be provided to protect the inner layers from aging. A problem that occurs, however, in forming both a hard coat layer and an antireflection layer on the surface of a plastic substrate is that the impact resistance of the lenses is low.
One means for improving the impact resistance of lenses comprising a low-refractive-index substrate, such as CR-39, is to form a thermosetting or thermoplastic resin layer between the substrate and the hard coat layer (JP-A-63-87223, JP-A-63-141001). However, lenses which have a high-refractive-index substrate, such as polythiourethane, and a resin layer, will exhibit interfacial light interference due to the difference in refractive index between the substrate and the hard coat layer. The result will be diminished optical quality, as well as inferior appearance. For lenses of that type, a technique of forming a primer layer of a thermosetting or thermoplastic resin that contains particles of dispersed metal oxide has been used (JP-A-9-80206, JP-A-9-291227). However, this method of incorporating particles of metal oxide in the primer layer is problematic in that the impact resistance of the lenses is lowered, even though the refractive index of the layer can be increased.
SUMMARY OF THE INVENTION
In order to overcome many of the problems in the prior art, the invention provides a high-refractive-index thin film layer, which has good impact resistance, good adhesiveness between the substrate and the thin film layer, good scratch resistance and good antireflection capabilities.
The invention provides a coating composition for optical parts, and in particular, a thin film layer on the substrate surface. The thin film layer is preferably formed by curing the coating composition. Also provided is a method for producing optical parts, which comprises applying the coating liquid onto the surface of a synthetic resin substrate to form thereon a thin film layer.
In one aspect, the invention provides a coating composition for optical parts, which comprises:
(i) a dithian ring containing sulfur compound of the general formula (1):
wherein n is an integer from 1 to 3, or a benzene ring containing sulfur compound of the general formula (2):
wherein m is 0 or 1, and
(ii) a polyfunctional thiol.
In a preferred embodiment, the polyfunctional thiol is at least one thiol selected from the group consisting of 2,5-dimercaptomethyl-1,4-dithian and its oligomers, 1,2,3-trimercaptopropane, tetrakis(7-mercapto-2,5-dithiaheptyl)methane, pentaerythritol tetrakis(2-mercaptoacetate), 4,4′-thiodibenzenedithiol, bis(4-mercapto-2-thiobutylphenyl) sulfide and bis(7-mercapto-2,5-dithiaheptylphenyl) sulfide.
In another embodiment, the thin film layer can be applied to an optical part, and the optical part can further comprise a hard coat layer and an antireflection layer on the thin film layer. The hard coat layer can comprise particles of metal oxide and an organic silicon compound. The optical part can be an eyeglass lens.
Yet another aspect of the invention provides a method for producing optical parts, comprising the steps of:
(A) applying a coating liquid onto a surface of a plastic substrate, and
(B) forming a thin film of said coating liquid, wherein said coating liquid comprises
(i) a dithian ring containing sulfur compound of a general formula (1A):
wherein n is an integer from 1 to 3, or a benzene ring containing sulfur compound of the general formula (2A):
wherein m is 0 or 1, and
(ii) a polyfunctional thiol.
The method can further comprise the steps of forming a hard coat layer and an antireflection layer on the thin film layer.
DETAILED DESCRIPTION OF THE INVENTION
We have found that when a thin film layer of a coating composition for optical parts comprises (1) a dithian ring containing sulfur compound and/or a benzene ring containing sulfur compound, and (2) a polyfunctional thiol compound formed on the surface of a plastic substrate, the resulting optical parts have good impact resistance and good adhesion between the substrate and the overlying layer. These good qualities remain even when a hard coat film and an antireflection film are further formed on the thin film layer.
The coating composition for optical parts comprises (1) a dithian ring containing sulfur compound and/or a benzene ring containing sulfur compound, and (2) a polyfunctional thiol compound. Preferred examples of the dithian ring containing sulfur compounds of formula (1) include 2,5-bis(2-thia-3-butenyl)- 1,4-dithian (n=1 in formula (1)), 2,5-bis(3-thia-4-pentenyl)-1,4-dithian (n=2 in the same), 2,5-bis(4-thia-5-hexenyl)-1,4-dithian (n=3 in the same), etc.
Preferred examples of the benzene ring containing sulfur compounds of formula (2) include bis(4-vinylthiophenyl) sulfide (m=0 in formula (2)), bis(4-vinylthiomethylphenyl) sulfide (m=1 in the same), etc.
Preferred polyfunctional thiol compounds that can be used in the invention are 2,5-dimercaptomethyl-1,4-dithian (hereinafter referred to as DMMD), DMMD oligomers, 1,2,3-trimercaptopropane, tetrakis(7-mercapto-2,5-dithiaheptyl)methane, pentaerythritol tetrakis(2-mercaptoacetate), 4,4′-thiodibenzenedithiol, bis(4-mercapto-2-thiobutylphenyl) sulfide, bis(7-mercapto-2,5-dithiaheptylphenyl) sulfide, etc. These compounds can be used either singly or in combination.
In addition to those mentioned above, other polyfunctional thiols can be used. Included are aliphatic polythiols such as methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-methylcyclohexane-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, 2,3-dimercapto-1-propanol (2-mercaptoacetate), 2,3-dimercapto-1-propanol (3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl) ether, ethylene glycol bis(2-mercaptoacetat
Jiang Jian
Ohta Hiroshi
Beck Shrive P.
Hoya Corporation
Morrison & Foerster / LLP
Tsoy Elena
LandOfFree
Coating composition and thin film layer for optical parts does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coating composition and thin film layer for optical parts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coating composition and thin film layer for optical parts will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2898067