Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-08-25
2003-03-04
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S301000, C526S302000, C526S303100, C526S304000, C526S307200, C427S214000, C427S220000, C427S219000, C502S063000
Reexamination Certificate
active
06528604
ABSTRACT:
DESCRIPTION OF BACKGROUND ART
1. Field of the Invention
The present invention relates to reactive silica, a process for manufacturing the same, and use of the same. More particularly, the present invention relates to reactive silica particles which can provide a curable composition with superior storage stability and capability of producing a coating film on the surfaces of substrates, such as plastics, metals, wood, papers, glasses, slates, or the like. The coating film exhibits excellent characteristics, such as scratch resistance, weather resistance, adhesiveness, and curability. The film can be made to satisfy a wide spectrum of performances from transparent to semi-transparent, and from a glossy surface to a frosty surface. The film can for example be applied to the surface of molded articles made from polymers, such as polycarbonate, polymethacrylate, polyvinyl chloride, polyester or polyolefins, to protect the surface from scratch and contamination. The composition can be used as a material for plastic optical parts and touch panels, film-type liquid crystal elements, hard coatings of plastic molded articles, a photocurable adhesive, a photocurable sealing material, a contamination-proof or scratch-proof coating for building interior materials, a flooring material, a material for walls, or a binder for printing ink.
2. Prior Art
In recent years there is a demand for a material which can be used to make for example coatings that are excellent in characteristics, such as scratch resistance, weather resistance, adhesiveness, and curability, and which can be controlled with respect to the optical characteristics in a wide range from-transparent to semi-transparent. Various coating compositions containing colloidal silica have been proposed with an object of improving the scratch resistance of the cured coatings. For example, U.S. Pat. No. 3,451,838 and U.S. Pat. No. 2,404,457 disclose a thermoset coating composition containing an alkoxysilane hydrolyzate and colloidal silica as major components. Japanese Patent Publication (kokoku) No. 21815/1987 discloses a photocurable coating composition containing colloidal silica particles, of which the surface is modified with methacryloxy silane, and acrylate. In these compositions, the surface of silica particles is treated with a specific organic silane compound or under specific conditions to improve their characteristics as a coating material.
These coating materials, however, are not able to meet all the required properties such as constantly producing films which exhibit excellent scratch resistance, weather resistance, adhesiveness, and curability, and furthermore can be formulated to satisfy a wide spectrum of performances from transparency to semi-transparency, and to provide a glossy surface as well as a frosty surface.
In addition, the thermoset coating compositions disclosed, for example, by U.S. Pat. No. 3,451,838 and U.S. Pat. No. 2,404,357 require a heat treatment at high temperatures for a long time and, therefore, cannot be applied to low heat resistant plastic materials.
SUMMARY OF THE INVENTION
An object of the present invention is to provide reactive silica particles comprising silica particles and an organic compound chemically bonded to the silica particles via a silyloxy group, wherein the organic compound has a polymerizable unsaturated group, a group represented by the following formula (1),
(wherein X is a group selected from —NH—, —O—, and —S— and Y is a group selected from oxygen and sulfur, provided that when X is —O—, Y is a sulfur atom), and a group represented by the following formula (2),
(wherein Z is a group selected from oxygen and sulfur)
Another object of the present invention is to provide a process for manufacturing reactive silica particles comprising, hydrolizing (a) a compound containing a hydrolyzable silyl group, a polymerizable unsaturated group, a group of the above formula (1), and a group of the above formula (2) in the molecule (this compound is hereinafter referred to as “hydrolyzable silane modified with a polymerizable unsaturated group”) and reacting said hydrolyzed compound with (b) silica particles selected from powdery silica or colloidal silica, causing the hydrolyzable silane modified with a polymerizable unsaturated group (a) and the silica particles (b) to chemically bond together.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The process of the present invention is first illustrated, and then the reactive silica particles of the present invention will be illustrated.
Process for Manufacturina the Hydrolyzable Silane Modified with a Polymerizable Unsaturated Group
The hydrolyzable silane modified with a polymerizable unsaturated group (a) used in the process of the present invention is characterized by comprising at least one group represented by the above formula (1), at least one group represented by the above formula (2), and at least one polymerizable unsaturated group. The hydrolyzable silyl group is a component capable of bonding to the silanol group which is present on the surface of silica particles by a hydrolysis or condensation reaction. The polymerizable unsaturated group is a component capable of crosslinking molecules by the addition reaction by the action of active radicals. The groups represented by the formula (1) or (2) are constitutional units which bind the molecules having the hydrolyzable silyl group and the molecules having the polymerizable unsaturated group directly or via other molecules. These groups are considered to provide the cured composition with excellent mechanical strength and superior characteristics such as good adhesion to substrates, heat resistance, and the like.
The hydrolyzable silyl group can for example be a carboxylate silyl groups such as an acetoxy silyl group; an alkoxy silyl group such as a methoxy or ethoxy silyl group; halogenated silyl groups such as chloro silyl group; amino silyl groups; oxime silyl groups; and hydride silyl groups. The hydrolyzable silyl group is defined as the group capable of forming a silanol group (—SiOH) by the reaction with water, optionally aided by the use of a catalyst such as for instance an acid or a base. Among the groups given above, the alkoxy silyl group is preferred.
The following groups are included in the group represented by the formula (1).
As examples of the polymerizable unsaturated group, acryloxy group, methacryloxy group, vinyl group, propenyl group, butadienyl group, styryl group, ethynyl group, cinnamoyl group, maleate group, acryl amide, and the like are given.
The compounds represented by the following formula (3) can be given as preferred examples of the hydrolyzable silane modified with a polymerizable unsaturated group (a).
wherein X
1
is an alkoxy group, carboxylate group, halogen atom, amino group, oxime group or hydrogen atom; and R
2
represents a hydrogen atom or a monovalent organic group having 1-8 carbon atoms, such as an alkyl group, aryl group, aralkyl group, or nonhydrolyzable organic group consisting of carbon, oxygen and hydrogen atoms.
Among various groups represented by X
1
, given as examples of the alkoxy group are methoxy, ethoxy, isopropoxy, butoxy, phenoxy, and octyloxy groups; as examples of the carboxylate group, acetoxy group; as examples of the halogen atom, iodine, chlorine, bromine, and fluorine; as examples of the amino group, monoalkyl amino groups such as amino group and methylamino group, dialkyl amino groups such as dimethylamino group and diethylamino group; and as examples of the oxime group, methylene oxime and dimethylmethylene oxime groups. m denotes 1, 2, or 3. Among these groups, the alkoxy groups are preferred.
Among various groups represented by R
2
, given as examples of the alkyl group are methyl, ethyl, propyl, butyl and octyl groups; as examples of the aryl group, phenyl, tolyl, xylyl, and p-methoxyphenyl groups; and as examples of the aralkyl group, benzyl and phenylethyl groups; and as examples of the nonhydrolyzable organic group consisting of carbon, oxygen and hydrogen atoms, 2-methoxyethyl, 2-ethox
Baba Atsushi
Eriyama Yuichi
Ukachi Takashi
Choi Ling-Siu
DSM N.V.
Wu David W.
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