Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-11-28
2002-07-09
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S193000, C526S259000, C526S320000, C526S328500
Reexamination Certificate
active
06417306
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a production process and a use for a transparent heat-resistant resin having both transparency and heat resistance, a production process therefor, and its use, more particularly, to a production process for a transparent heat-resistant resin, which is preferably used for such as optical materials and automobile materials to need shape stability and colorless transparency in a high temperature because of being excellent in heat resistance; a production process therefor; and its use.
B. Background Art
It is known that thermoplastic resins having a good balance with various physical properties such as heat resistance, heat stability, mechanical strength, and moldability, can be produced by copolymerizing high copolymerizable maleimide monomer and other monomer such as methacrylic acid ester up to now.
Among these thermoplastic resins, a thermoplastic resin obtained by copolymerizing methacrylic acid ester monomer and maleimide monomer is excellent in transparency and heat resistance, and becomes often used for the fields to need heat resistance and transparency, such as optical materials and automobile materials. Particularly, it is generally known to introduce the maleimide monomer much more if the resin needs more higher heat resistance.
When polymerizing the methacrylic acid ester monomer, a chain-transfer agent such as mercaptan is used in order to suppress to form a terminal double bond by disproportionation termination and to adjust molecular weight. The double bond by disproportionation termination is formed in the polymer terminal and pyrolysis by zipping is easily arises unless the chain-transfer agent is used. However, if using the chain-transfer agent, a Michael adduct of such as the mercaptan and the maleimide monomer during the polymerization is formed and a reverse reaction is carried out in a heat treatment process (such as devolatilization and granulation) after the polymerization. As a result, the maleimide monomer remained much.
If the maleimide monomer remains much, the much maleimide monomer evaporates and disperses from the melting resin when heat processing the resin as obtained. In recent years, the toxicity of the maleimide monomer is considered, and the influence on human body and environment is feared. In addition, it is feared to give the similar danger to such as a worker if the maleimide monomer is generated by pyrolysis because the heat stability of the resin is not sufficient and the resin is heated in order to carry out a mold processing.
On the other hand, if polymerizing comonomers including the maleimide monomer, there was a problem that yellowness is easily caused by heating during the polymerization or the mold processing. For example, if the Michael adduct and the residual maleimide monomer thereby become much, an amine compound is generated and yellowness is caused easily by the amine compound. Particularly, it is known that arylamine has a great influence on the yellowness when using arylmaleimide that generates the arylamine.
Until now, as a method for decreasing the residual maleimide monomer, for example, JP-A-141715/1986 and JP-A-171708/1986 disclose arts of: carrying out a suspension polymerization of N-phenylmaleimide/methyl methacrylate, and washing by alcohol or carrying out styrene copolymerization in order to decreasing the residual maleimide monomer. However, the residual maleimide monomer is still much by these methods. Moreover, only a yellowish polymer has obtained.
In addition, as a method for decreasing yellowness, for example, JP-A-175711/1990 discloses an art of: suppressing hydrolysis of the maleimide monomer by controlling pH during the suspension polymerization, and decreasing the generation of the amine compound that causes yellowness. However, the effects in a reaction system including N-phenylmaleimide that causes yellowness as mentioned above conspicuously, is not reported. Moreover, the residual maleimide monomer was still much.
In addition, JP-A-324016/1997 discloses an art of: decreasing the residual maleimide monomer and yellowness also by controlling a supplying method of the monomer in the solution polymerization. The residual maleimide monomer considerably decreased thereby. However, heat stability was deteriorated and the maleimide monomer generated by heating in order to carry out such as a mold processing was much in the existing circumstances.
In this way, until now, in transparent heat-resistant resins derived from a methacrylic acid ester monomer/a maleimide monomer, it was difficult to fulfill decreasing the residual maleimide monomer and the maleimide monomer generated by heating in order to carry out such as a mold processing, and suppressing yellowness at the same time.
SUMMARY OF THE INVENTION
A. Object of the Invention
Therefore, an object of the present invention is to provide: a transparent heat-resistant resin that has a small amount of both the residual maleimide monomer and the maleimide monomer generated by heating in order to carry out such as a mold processing, and further, is excellent in heat resistance and yellowish little; a production process therefor; and a resin composition utilizing this resin.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above problems. As a result, they found that Michael adducts formed as by-products during the polymerization are decreased and hydrolysis of a maleimide monomer can be suppressed at the same time by making an acidic substance exist in the polymerization system for polymerizing a methacrylic acid ester monomer/a maleimide monomer by use of a chain-transfer agent such as mercaptan. Thereby, they also found that: even in case of introducing N-substituted maleimide that can give high heat resistance only, the residual maleimide monomer and the maleimide monomer generated by heating in order to carry out such as a mold processing are decreased and the yellowness can be suppressed. Then, the present invention was completed.
That is to say, a transparent heat-resistant resin, according to the present invention, is obtained by a process including the step of running a polymerization of comonomers including a maleimide monomer and a methacrylic acid ester monomer, wherein: the amount of the residual maleimide monomer in the resin is not more than 10×ppm when the amount of a structural unit derived from the maleimide monomer is X weight % in the resin, and the amount of the generated maleimide monomer by heating the resin at 240° C. for 10 minutes is not more than 10×ppm when the amount of a structural unit derived from the maleimide monomer is X weight % in the resin.
In addition, a production process for a transparent heat-resistant resin, according to the present invention, comprises the step of running a polymerization of comonomers including a maleimide monomer and a methacrylic acid ester monomer in order to obtain a transparent resin having heat resistance, with the production process being characterized by making an acidic substance exist with a sulfur chain-transfer agent in the polymerization system during the polymerization.
In addition, a resin composition, according to the present invention, comprises the transparent heat-resistant resin according to the present invention, and a synthetic resin except for the transparent heat-resistant resin.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
<Production Process for the Transparent Heat-resistant Resin>
(Comonomers)
The production process for a transparent heat-resistant resin, according to the present invention, comprises the step of running a polymerization of comonomers including a maleimide monomer and a methacrylic acid ester monomer. The heat stability of the resin as obtained can be improved because the comonomers include the maleimide monomer, and transparency can be given to the resin as obtained because the comonomers include t
Makino Tomomi
Ueda Ken-ichi
Yamaguchi Minoru
Nippon Shokubai Co. Ltd
Pezzuto Helen L.
Roylance Abrams Berdo & Goodman L.L.P.
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