Stock material or miscellaneous articles – Composite – Of polycarbonate
Reexamination Certificate
2000-02-29
2001-12-25
Boykin, Terressa M. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polycarbonate
C264S176100, C528S196000, C528S198000
Reexamination Certificate
active
06333114
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thermoplastic aromatic polycarbonate molded article which has improved weatherability and improved resistance to coloring. More particularly, it relates to a coextruded polycarbonate resin article having improved weatherability and improved coloring resistance which comprises a thermoplastic aromatic polycarbonate resin core layer having on at least one side thereof a thermoplastic aromatic polycarbonate resin cover layer containing a triazine light stabilizer and is useful as various molded articles such as food packaging containers, interior and exterior automotive trim parts, and precision machines, films, constructional materials, and the like.
Polycarbonate resins are widely used as windowpanes, roofing materials for arcades, food packaging containers, automotive parts, precision machines, etc. for their strength, rigidity, wear resistance, chemical resistance, and transparency.
However, polycarbonate resins have limited applicability because they have insufficient weatherability and are prone to discoloration or strength reduction when used outdoors or under fluorescent lamps.
Hence, polycarbonate resins have been used in combination with one or more than one of various light stabilizers. In particular, benzotriazole light stabilizers are in general use because of their relatively high effects. Benzotriazole light stabilizers are effective to some extent but still insufficient for imparting resistance to coloring by high-temperature processing, leaving room for further improvement.
Further, polycarbonate resins easily receive damage to the surface by intense ultraviolet radiation, developing a great number of fine crazes on the essentially glossy surface, which results in haze.
Polycarbonate resin molded articles having a core layer on which a light stabilizer-containing cover layer is provided by coextrusion to protect the surface have been proposed as disclosed, e.g., in Japanese Patent Laid-Open No. 101360/84, but they are disadvantageous in that the resin is colored. Japanese Patent Laid-Open No. 165419/89 discloses a polycarbonate resin coextruded article having a cover layer containing a benzotriazole light stabilizer. This technique involves the problem that the resin is colored when processed at an extremely high temperature of 300° C. or higher with a large amount of the light stabilizer compounded therein. British Patent 2290745 describes a polycarbonate resin coextruded article having a cover layer containing a triazine light stabilizer. However, sufficient weatherability is not obtained due to poor compatibility of the light stabilizer with the resin component.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a polycarbonate resin coextruded article having a core layer and a cover layer which exhibits improved weatherability and improved resistance to coloring by high-temperature processing.
As a result of extensive investigations, the present inventors have found that the above object is accomplished by a polycarbonate resin coextruded article having a core layer and a cover layer wherein the cover layer contains a triazine ultraviolet absorber having a specific structure. The present invention has been completed based on this finding.
The present invention provides a polycarbonate resin coextruded article having a core layer comprising a thermoplastic aromatic polycarbonate resin and a cover layer comprising a thermoplastic aromatic polycarbonate resin which is provided on at least one side of the core layer, wherein the cover layer comprises a resin composition comprising 100 parts by weight of a thermoplastic aromatic polycarbonate resin and 0.1 to 25 parts by weight of a triazine light stabilizer represented by formula (I):
wherein R
1
represents an alkyl group having 1 to 17 carbon atoms; R
2
represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and n represents an integer of 1 to 20.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The polycarbonate resin composition according to the invention will be described in detail with reference to the preferred embodiments thereof.
The thermoplastic aromatic polycarbonate resin which can be used in the present invention preferably includes polycarbonic esters of bisphenol compounds. The bisphenol compounds include bisphenols, such as bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A), 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4-bis(hydroxyphenyl)heptane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, and 2,2-bis(4-hydroxy-3,5-dibromophenylpropane; diphenyl ethers, such as bis(4-hydroxyphenyl) ether and bis(3,5-dichloro-4-hydroxyphenyl) ether; dihydroxydiphenyls, such as p,p′-dihydroxydiphenyl and 3,3′-dichloro-4,4′-dihydroxydiphenyl; dihydroxyaryl sulfones, such as bis(4-hydroxyphenyl) sulfone, bis(3,5-dimethyl-4-hydroxyphenyl) sulfone; dihydroxybenzenes, such as 1,4-dihydroxy-2,5-dichlorobenzene and 1,4-dihydroxy-3-methylbenzene; resorcinol, hydroquinone, halogen-and alkyl-substituted dihydroxybenzenes; and dihydroxyphenyl sulfoxides, such as bis(4-hydroxyphenyl) sulfoxide and bis(3,5-dibromo-4-hydroxyphenyl) sulfoxide. Other various bisphenol compounds and triphenol compounds are also useful. The bisphenol compounds can be used either individually or as a mixture thereof
The thermoplastic aromatic polycarbonate resins can be prepared by, for example, the reaction between a dihydric phenol and a carbonate precursor. The carbonate precursor includes carbonyl halides, carbonic esters and haloformates. Examples of the carbonyl halides are carbonyl bromide, carbonyl chloride and a mixture thereof. Examples of the carbonic esters are diphenyl carbonate, di(chlorophenyl) carbonate, ditolyl carbonate, dinaphthyl carbonate, and mixtures thereof. Examples of the haloformates are dihydric phenol haloformates, such as hydroquinone bischloroformate, and glycol haloformates, such as ethylene glycol haloformate. Preferred of them is carbonyl chloride, which is known as phosgene.
The thermoplastic aromatic polycarbonate resins are prepared by using a molecular weight regulator and an acid acceptor. Suitable molecular weight regulators include phenol cyclohexanol, methanol p-t-butylphenol, and p-bromophenol, with p-t-butylphenol being preferred. The acid acceptors may be organic or inorganic. Examples of the organic acid acceptors include pyridine, triethylamine, and dimethylaniline. Examples of the inorganic acid acceptors include hydroxides, carbonates, hydrogencarbonates or phosphates of alkali metals or alkaline earth metals.
In the light stabilizers represented by formula (I) or (II), the alkyl group as represented by R
1
includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, sec-pentyl, t-pentyl, hexyl, isohexyl, heptyl, 1-ethylpentyl octyl isooctyl 1,1,3,3-tetramethylbutyl, nonyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl hexadecyl, and heptadecyl.
The alkyl group as represented by R
2
in formulae (I) and (II) includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and t-butyl,
In formula (I), n represents an integer of 1 to 20, preferably an integer of 1 to 10.
Specific examples of the triazine light stabilizers represented by formula (I) include the following compounds.
The triazine light stabilizer of formula (I) can be synthesized by any known method generally employed for triaryltriazine compounds with no particular restriction. For example, compound No. 1 is prepared by esterifying 2-(2-hydroxy-4-(2′-hydroxyethoxy)-4,6-di(2,4-diphenyl)triazine.
The polycarbonate resin molded article of the present invention is a coextruded article composed of a core layer comprising the above-described thermoplastic aromatic polycarbonate resin and a cover layer comprising the above-described thermoplastic aromatic polycarbonate resin which is provided on at least one side of the core layer.
The polycarbonate resin coextruded article is produced by coextrud
Ayabe Takashi
Ishikawa Shin-ichi
Kawaragi Saeko
Tobita Etsuo
Asahi Denka Kogyo Kabushiki Kaisha
Boykin Terressa M.
Young & Thompson
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