Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2002-04-23
2003-10-21
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S330000, C428S403000, C428S432000, C428S469000, C428S689000, C428S701000, C428S702000, C428S407000, C428S472000, C525S100000, C525S105000, C526S285000, C526S333000, C106S285000, C106S287100, C106S287160, C106S287170, C106S287190, C106S287260
Reexamination Certificate
active
06635352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a coating composition, a process for producing optical elements having excellent durability as well as good film hardness, scratch resistance and adhesion using the coating composition; and to optical elements produced by the process.
2. Description of the Related Art
Various methods have been proposed for improving the scratch resistance of plastic lenses which include coating plastic lenses with a coating composition made of an organosilicon compound as the major raw material, followed by curing the lenses to form a cured film thereon. The scratch resistance of plastic lenses is generally improved by employing a technique of increasing the content of inorganic oxide fine particles in the coating composition.
For example, Japanese Laid-Open Patent Application No. 10640/1988 discloses an optical element comprising a cured film made of a coating composition applied to a plastic lens substrate, the coating composition for which contains high-concentration colloidal silica, a type of fine inorganic particles, and a trifunctional organic compound. The high-concentration colloidal silica accounts for from 70 to 95 mole % (in terms of its solids content) based on the total amount of the composition.
However, the optical element disclosed in the above-cited patent, which has a cured film containing high-concentration inorganic fine particles, is problematic in that the stresses generated by the substrate and the high-concentration inorganic fine particles-containing cured film are liable to lower the adhesion between the cured film and the antireflection film formed thereon.
Methods of adding high-concentration inorganic fine particles to the coating film or increasing the degree of crosslinking in the film are generally employed for hardening the coating film. Anyhow, when the coating film is hardened, the hard film does not absorb the stress change resulting from the antireflection film formed thereon, and the interface between the hard film and the antireflection film is distorted, thereby lowering significantly the adhesion between the two films.
SUMMARY OF THE INVENTION
This invention provides a coating composition capable of forming a cured film having excellent scratch resistance and excellent adhesion between the cured film and an antireflection film formed thereon, an optical element having excellent scratch resistance, whose adhesion between the cured film and the antireflection film is little impaired, and a process for producing such optical elements.
In accordance with the invention, a coating composition for a cured film to be formed between a plastic substrate and an antireflection film made of an inorganic oxide contains an organosilicon compound and an adhesion improver made of an acetylene compound having a specific structure as described below.
Specifically, the invention provides a coating composition for forming a cured film between a plastic substrate and an antireflection film made of an inorganic oxide, which contains an organosilicon compound and an adhesion improver made of an acetylene compound of the general formulas (I-a) to (I-d):
wherein R
a
and R
c
each independently represent a hydrogen atom or an optionally branched alkyl group having from 1 to 5 carbon atoms; R
b
and R
d
each independently represent an optionally branched alkyl group having from 2 to 8 carbon atoms; R
e
and R
f
each independently represent an optionally branched alkyl group having from 1 to 3 carbon atoms; m and n each indicate an integer of 1 or more; and m′ and n′ each indicate an integer of 0 or more;
The invention also includes a process for producing optical elements, which comprises forming a cured film of the coating composition described herein on a plastic substrate, and forming an antireflection film of an inorganic oxide on the cured film, as well as an optical element having a cured film made of the coating composition formed on a plastic substrate, and having an antireflection film made of an inorganic oxide formed on the cured film, which may be produced by this process.
DETAILED DESCRIPTION OF THE INVENTION
The coating composition of the invention contains an acetylene glycol compound of formula (I-a) or (I-b), or an acetylene compound of formula (I-c) or (I-d), and the adhesion between its cured film and the antireflection film that overlies it is good for a long time even when the cured film contains high-concentration inorganic fine particles. When the antireflection film contains a metal atom but not a metal oxide, the affinity between the metal atom and the triple bond in the acetylene glycol compound of formula (I-a) or (I-b), a type of acetylene compounds, or that in the acetylene compound of formula (I-c) or (I-d), is better and the metal atom itself relaxes the stress of the antireflection film. In this case, therefore, the adhesion between the cured film and the antireflection film is higher.
In formulas (I-a) and (I-b), R
a
and R
c
each represents a hydrogen atom or an optionally branched alkyl group. For these, preferred is a linear or branched alkyl group having from 1 to 5 carbon atoms, including, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and pentyl groups. For R
b
and R
d
each representing an optionally branched alkyl group, preferred is a linear or branched alkyl group having from 2 to 8 carbon atoms, including, for example, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and pentyl groups. m and n independently are integers of 1 or more, and preferably from 4 to 12.
The acetylene glycol compound of formula (I-a) is, for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol. The acetylene glycol compound of formula (II) is, for example, an adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol having from 3 to 10 moles of polyoxyethylene added thereto.
The acetylene compounds of formulas (I-a) and (I-b) are known and are disclosed in, for example, Japanese Laid-Open Patent Application Nos. 53570/1984, 161473/1985, 99217/1988, 63288/1991, 163038/1991, 188087/1995, 265690/1998 and 20104/1999; International Patent Publication No. 503050/2000; Japanese Laid-Open Patent Application Nos. 43601/1996, 43602/1996, 43603/1996 and 43604/1996. However, the applications of the compounds disclosed in these documents are as surfactants for improving the defoaming property of the compositions containing the compound and for improving the dispersibility and the wettability of a dye in the compositions, without any suggestions of the use of these acetylene glycol compounds for improving the long-lasting adhesion to an antireflection film of a cured film even though it contains high-concentration inorganic fine particles, as in this invention.
The content of the acetylene glycol compound of formula (I-a) or (I-b) in the coating composition preferably ranges from 1 to 5% by weight based on the total weight of the composition.
The acetylene compounds of formulas (I-c) or (I-d) are novel compounds that are obtained starting from the acetylene glycol compounds of formulas (I-a) or (I-b). For producing them, the hydroxyl group that is present at the &agr;-position relative to the triple bond in formula (I-a), or the terminal hydroxyl group of the polyethylene glycol that is presented at the &agr;-position relative to the triple bond in formula (I-b), is reacted. The solvent to be used for the reaction is methylene chloride. Using 2.2 equivalents of tosyl chloride, 3 equivalents of triethylamine and 0.1 equivalents of dimethylaminopyridine, the starting compound is tosylated, and then 2.2 equivalents of an alkyne compound such as methylacetylene (propyne) is added thereto and reacted to obtain the intended compound. The reaction solvent to be used may be anhydrous THF.
In formulas (I-c) and (I-d), R
a
and R
c
each represents a hydrogen atom or an optionally branched alkyl group. For these, preferred is a linear or branched alkyl group having from 1 to 5 carbon atoms, including, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-bu
Hoya Corporation
Morrison & Foerster / LLP
Xu Ling
LandOfFree
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