Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-07-24
2002-08-13
Reddick, Judy M. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C428S001100, C524S087000, C524S236000, C524S239000, C524S533000, C524S095000, C524S102000, C525S304000
Reexamination Certificate
active
06433044
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a methyl methacrylate resin composition and a molded article thereof. More specifically, it relates to a methyl methacrylate resin composition containing an ultraviolet absorber, and a molded article thereof.
2. Description of the Related Art
As a conventional method to improve the durability of a methyl methacrylate resin composition, a method including addition of an ultraviolet absorber to the composition is known. For instance, JETI, vol.46, No. 5, p.116-121 (1998) discloses use of a salicylate, cyano acrylate or benzotriazole compound as an ultraviolet absorber to be added to methyl methacrylate resins.
In the case where a methyl methacrylate resin blended with ultraviolet absorbers conventionally used is molded into an optical article, however, light transmitted through the optical article may be somewhat colored presumably due to the power absorbing viewable light of the ultraviolet absorbers used, hence, the transparency of the molded optical article may be insufficient. This problem becomes noticeable particularly when a transmitted optical path length of the molded optical article is long.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a methyl methacrylate resin composition exhibiting superior durability without impairing the transparency inherent to a methyl methacrylate resin.
The present inventors made intensive have studied a methyl methacrylate resin composition exhibiting superior durability without impairing the transparency inherent to a methyl methacrylate resin, as a result, found that a methyl methacrylate resin composition containing a 2-(1-arylalkylidene)malonic acid ester exhibits superior durability without impairing the transparency inherent to a methyl methacrylate resin, and have completed the present invention.
That is, the present invention provides a methyl methacrylate resin composition comprising a methyl methacrylate resin and a 2-(1-arylalkylidene)malonic acid ester in an amount of about 0.0005 to about 0.1 parts by weight per 100 parts by weight of the methyl methacrylate resin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will hereinafter be described in detail.
In the present invention, the methyl methacrylate resin is a polymer comprising not less than about 50% by weight of methyl methacrylate as a monomer forming the resin. An example of such a polymer is a polymer comprising not less than about 50% by weight of poly methyl methacrylate, which is essentially a monopolymer of methyl methacryate, or a copolymer comprising methyl methacrylate and not more than about 50% by weight of an unsaturated monomer, which is copolymerizable therewith.
Examples of unsaturated monomers which are copolymerizable with methyl methacrylate include methacrylic acid esters such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; styrene, &agr;-methylstyrene, acrylonitrile, methacrylonitrile, maleic acid anhydride, phenylmaleimide, and cyclohexylmaleimide. Two or more of these unsaturated monomers may be used in combination if necessary. The aforementioned copolymer may contain a glutaric acid anhydride unit or a glutarimide unit.
In terms of moldability, alkyl acrylates such as methyl acrylate are preferred as the unsaturated monomer, which is copolymerizable with methyl methacrylate. When such an alkyl acrylate is contained as the unsaturated monomer, the composition of the monomers used in the copolymer preferably comprises about 80 to about 99.5% by weight of methyl methacrylate and about 0.5 to about 20% by weight of the alkyl acrylate.
In terms of its lower water absorption property, styrene is preferred as the unsaturated monomer, which is copolymerizable with methyl methacrylate. When styrene is contained as the unsaturated monomer, the composition of the monomers used in the copolymer preferably comprises about 60 to about 90% by weight of methyl methacrylate and about 10 to about 40% by weight of styrene.
According to the present invention, a 2-(1-arylalkylidene)malonic acid ester is contained in the methyl methacrylate resin to provide a methyl methacrylate resin composition having superior transparency and durability. In terms of durability, an amount of the 2-(1-arylalkylidene)malonic acid ester is not less than about 0.0005 parts by weight, preferably not less than about 0.003 parts by weight, more preferably not less than about 0.005 parts by weight, per 100 parts by weight of the methyl methacrylate resin. In terms of transparency, the content of the 2-(1-arylalkylidene)malonic acid ester is not more than about 1 part by weight, preferably not more than about 0.05 parts by weight, more preferably not more than about 0.03 parts by weight, per 100 parts by weight of the methyl methacrylate resin.
Among 2-(1-arylalkylidene)malonic acid esters, those represented by the following general formula (1) are preferred in terms of durability;
wherein X represents a hydrogen atom, an alkyl group having 1 to about 6 carbon atoms or an alkoxy group having 1 to about 6 carbon atoms, and R
1
and R
2
independently represent an alkyl group having 1 to about 6 carbon atoms.
In the formula (1), X is preferably a hydrogen atom, an alkyl group having 1 to about 4 carbon atoms or an alkoxy group having 1 to about 4 carbon atoms. The alkyl group represented by X or the alkyl group in the alkoxy group represented by X may be either in a straight-chain form or in a branched-chain form. Examples of such alkyl groups include a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, and t-butyl group. More preferably, X is a methoxy group.
Preferably, R
1
and R
2
in the formula (1) are each an alkyl group having 1 to about 4 carbon atoms. The alkyl group represented by R
1
or R
2
may be either in a straight-chain form or in a branched-chain form. Examples of such alkyl groups include a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, and t-butyl group. More preferably, R
1
and R
2
are each a methyl group.
The composition of the present invention may contain a hindered amine such as a compound having a 2,2,6,6-tetraalkylpiperidine skeleton for further improved durability. In this case, the content of such a hindered amine is usually not less than about 0.0001 parts by weight, preferably not less than about 0.001 parts by weight, more preferably not less than about 0.003 parts by weight, per 100 parts by weight of the methyl methacrylate resin. In terms of cost and transparency, an amount of the hindered amine is usually not more than about 0.1 parts by weight, preferably not more than about 0.05 parts by weight, more preferably not more than about 0.03 parts by weight. The content of the hindered amine per 100 parts by weight of the 2-(1-arylalkylidene)malonic acid ester is usually not more than about 100 parts by weight, preferably in the range of about 10 to about 80 parts by weight.
Examples of such hindered amines include a polycondensate of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, poly((6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperidyl)imino))hexamethylene((2,2,6,6-tetramethyl-4-piperidyl)imino, 2-(2,3-di-t-butyl-4-hydroxybenzyl)-2-n-bis(1,2,2,6,6-pentamethyl-4-piperidyl)butylmalonic acid, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-bis(1,2,2,6,6-pentamethyl-4-piperidyl)butylmalonic acid, a condensate of N,N′-bis(3-aminopropyl)ethylenediamine and 2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-6-chloro-1,3,5-triazine, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bi
Maekawa Tomohiro
Manabe Kenji
Reddick Judy M.
Sumitomo Chemical Company Limited
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