Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-09-18
2003-04-01
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S404000, C523S414000, C525S528000
Reexamination Certificate
active
06541541
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an aqueous resin composition and more particularly to an aqueous resin composition having high resistance to thermal coloring and suited for application to coatings on various substrates and sizing agents for fibrous materials such as glass fiber.
BACKGROUND OF THE INVENTION
Epoxy resins are widely used in coatings, adhesives, fiber treating agents, and the like for their excellent properties such as adhesion to various substrates, heat resistance, chemical resistance, and electrical and mechanical characteristics.
For ease in handling, epoxy resins for these applications have generally been supplied in the form of a solution in various low-boiling solvents, but use of low-boiling solvents has been restricted in view of the danger of fires, bodily harm, and adverse influences on the global environment. In recent years, aqueous resin compositions comprising an epoxy resin dispersed in water with the aid of an emulsifying agent have been developed and put to practical use.
On the other hand, fiber-reinforced plastics (FRPs) or fiber-reinforced thermoplastics (FRTPs) comprising a thermoplastic resin, such as polyolefins and polyesters, and a fibrous material, such as glass fiber, have been remarkably extending their use for their high strength and high rigidity.
In glass fiber production, molten glass is spun into filaments, and several hundreds to several thousands of the filaments are gathered into a bundle called a strand, which is cut to 3 to 6 mm lengths to obtain chopped strands, or several tens of the strands are bundled into a roving. A sizing agent is used to prevent glass filaments from splitting and fuzzing due to friction in the production of glass fibers or while blended with a thermoplastic resin.
Sizing agents conventionally applied to glass fiber or other fibrous materials include starch products, such as starch, processed starch, dextrin, and amylose (see JP-A-50-12394 and JP-A-3-183644); and synthetic polymers, such as carboxymethyl cellulose, polyvinyl alcohol, and an acrylamide-vinyl acetate copolymer (see JP-A-63-236733). These sizing agents have insufficient film-forming properties for sufficiently preventing glass fiber from fuzzing. They are also unsatisfactory in mechanical strength and hot water resistance.
To overcome these disadvantages, it has been proposed to use an aqueous resin comprising an epoxy resin as a sizing agent for fibrous materials. For example, JP-A-10-182951 discloses an aqueous epoxy resin dispersion suitable as a glass fiber sizing agent, which comprises a bisphenol type polyether compound comprising an alkylene oxide (80 to 800 mol) adduct of a bisphenol compound or a condensation product between the adduct and a polyisocyanate compound. The aqueous resin composition disclosed which contains a general epoxy resin still has the problem that FRPs or FRTPs containing the composition undergo coloring or have poor physical properties.
It has also been taught that a polyfunctional bisphenol type epoxy resin obtained by allowing epichlorohydrin to react with the secondary hydroxyl group of a general bisphenol compound diglycidyl ether is suitable for use in sealing materials for electric and electronic components, laminated sheets, etc. (see U.S. Pat. No. 4,623,701, JP-A-5-5020, JP-A-6-248055, and JP-A-6-298904). The publications, however, have no mention of preparation of an aqueous resin composition comprising these epoxy resins.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an aqueous resin composition suitable as a sizing agent for fibrous materials, such as glass fiber, that will provide fiber-reinforced resins resistant to thermal coloring and excellent in physical properties.
As a result of extensive investigation, the present inventors have found that an aqueous resin composition comprising a specific polyepoxy compound can be used as a sizing agent for fibrous materials, particularly glass fiber, to provide fiber-reinforced resin products which undergo no thermal coloring and exhibit excellent physical properties.
The present invention provides an aqueous resin composition comprising (A) a polyepoxy compound represented by formula (I):
wherein n represents a number of from 0.1 to 20; Z represents a single bond, an alkylidene group having 1 to 4 carbon atoms or SO
2
(sulfone group); and X represents a hydrogen atom or a glycidyl group, provided that at least 10% of nX's represent a glycidyl group, and water.
DETAILED DESCRIPTION OF THE INVENTION
In formula (I), the alkylidene group having 1 to 4 carbon atoms as represented by Z includes methylidene, ethylidene, propylidene, and butylidene. n represents 0.1 to 20, preferably 1 to 15. X represents a hydrogen atom or a glycidyl group, provided that at least 10%, preferably 30% or more, of nX's represent a glycidyl group.
Where n is smaller than 0.1, or where less than 10% of nX's represent a glycidyl group, the aqueous resin composition has an insufficient content of the polyfunctional epoxy compound having tri- or higher functionality and, when used as a fibrous material sizing agent, fails to provide a fiber-reinforced resin with satisfactory physical properties. If n exceeds 20, the resulting aqueous resin composition tends to have poor stability.
The polyepoxy compound which can be used in the present invention as component (A) (hereinafter referred to as the polyepoxy compound (A)) is easily prepared by allowing a bisphenol diglycidyl ether having at least one secondary hydroxyl group in the molecule and epichlorohydrin to react in the presence of an alkali and a phase transfer catalyst.
The alkali which can be used includes sodium hydroxide, potassium hydroxide, and calcium hydroxide. The phase transfer catalyst which can be used includes tetramethylammonium chloride, tetrabutylammonium bromide, methyltrioctylammonium chloride, methyltridecylammonium chloride, N,N-dimethylpyrrolidinium chloride, N-ethyl-N-methylpyrrolidinium iodide, N-butyl-N-methylpyrrolidinium bromide, N-benzyl-N-methylpyrrolidinium chloride, N-ethyl-N-methylpyrroldinium bromide, N-butyl-N-methylmorpholinium bromide, N-butyl-N-methylmorpholinium iodide, N-allyl-N-methylmorpholinium bromide, N-methyl-N-benzylpiperidinium chloride, N-methyl-N-benzylpiperidinium bromide, N,N-dimethylpiperidinium iodide, N-methyl-N-ethylpiperidinium acetate, and N-methyl-N-ethylpiperidinium iodide. Tetramethylammonium chloride is preferred of them.
Epichlorohydrin is used in an amount of an equivalent or more, particularly 2 to 10 equivalents, per hydroxyl equivalent of the diglycidyl ether. The alkali is used in an amount of 0.1 to 2.0 mol, particularly 0.3 to 1.5 mol, per equivalent of the hydroxyl group to be glycidylated. The phase transfer catalyst is used in an amount of 0.01 to 10 mol %, particularly 0.2 to 2 mol %, based on the total weight of the reactants.
The reaction is carried out in the presence of a solvent, such as a hydrocarbon, an ether or a ketone, or an excess of epichlorohydrin can serve as a solvent.
The reaction is performed at 20 to 100° C., particularly 30 to 80° C. At reaction temperatures lower than 20° C., the reaction is slow to require an extended reaction time. Temperatures higher than 100° C. induce unfavorable side reactions.
For the details of the reaction, reference can be made, e.g., in H. Batzer and S. A. Zahir,
Journal of Applied Polymer Science,
vol. 19, pp. 609-617 (1975). The process of producing a glycidyl ether of a secondary alcohol disclosed in JP-A-5-239181 is also applicable. Additionally, the processes using dimethyl sulfoxide taught in JP-A-1-168722 and JP-A-5-5020 are also effective.
The starting diglycidyl ether of a bisphenol compound having at least one secondary hydroxyl group per molecule is a known compound. It is obtainable by either a one-stage process in which a bisphenol compound and epichlorohydrin are allowed to react or a two-stage process in which a diglycidyl ether of a low-molecular bisphenol compound and a bisphenol compound are allowed to react. The st
Akimoto Koji
Fujita Naohiro
Masamune Kiyoshi
Ogawa Ryo
Asahi Denka Kogyo Kabushiki Kaisha
Aylward D.
Dawson Robert
Young & Thompson
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