Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-11-15
2004-09-21
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S340000, C525S353000
Reexamination Certificate
active
06794460
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, more particularly, to a production process and a use for a transparent heat-resistant resin, which process is characterized by involving a specific heating vacuum treatment.
B. Background Art
A methacrylic resin is excellent in transparency, surface gloss, and weather resistance and is well-balanced with regard to mechanical strength, molding processibility, and surface hardness, so the methacrylic resin is widely used for optical purposes of cars, home use electric appliances, and so on. However, the glass transition temperature (Tg) of the methacrylic resin is around 110° C. and is therefore difficult to use in fields where the heat resistance is demanded. On the other hand, light sources are often designed to be put in the vicinity of the resin to meet requests for the freedom degree of the design, the achievement of the compactness and high performance, and so on. Thus, a more excellent heat-resistant resin is desired.
Polym. Prepr., 8, 1, 576 (1967) discloses a process for obtaining a methacrylic resin having the heat resistance, in which process an alkyl 2-(hydroxymethyl)acrylate/methyl methacrylate copolymer or an &agr;-hydroxymethylstyrene/methyl methacrylate copolymer is allowed to run a dealcoholation reaction by heating under vacuum with an extruder to form a lactone ring due to condensation of hydroxyl group and ester group of the polymer, thus obtaining the heat-resistant resin. In this process, solution polymerization or bulk polymerization is carried out. In the case of the solution polymerization, the resultant polymer is separated in the form of a solid from polymerization reaction products, and then introduced into the extruder. In the case of the bulk polymerization, the solid polymer resultant from the polymerization is granulated without modification, and then introduced into the extruder. Therefore, this process is unfit for industrial production. Furthermore, in this process, when the content of the alkyl 2-(hydroxymethyl)acrylate or &agr;-hydroxymethylstyrene is increased, the resultant conversion of the dealcoholation reaction is low. As is seen in the case of the &agr;-hydroxymethylstyrene/methyl methacrylate copolymer, for example, when the content of &agr;-hydroxymethylstyrene in the polymer is 25%, the conversion of the dealcoholation reaction is 71%, and when the content of &agr;-hydroxymethylstyrene in the polymer is 30%, the conversion is 59%. Therefore, there are demerits, for example, in that when the resultant polymer is re-shaped by heating, the dealcoholation reaction proceeds to cause the molded product to foam. Another problem is that the production process is complicated because the solid polymer is transferred, or introduced into the extruder.
JP-A-09-241323 discloses another prior art in which, if poly[ethyl 2-(hydroxymethyl)acrylate], poly[alkyl 2-(hydroxymethyl)acrylate], or a polymer having a high content of ethyl 2-(hydroxymethyl)acrylate or alkyl 2-(hydroxymethyl)acrylate is used in a solid state in its dealcoholation reaction, then the polymer is crosslinked in the reaction to make melt-molding difficult, therefore the dealcoholation is carried out in a solution state as made by: once obtaining the polymer in a solid state by reprecipitation, and then re-dissolving the resultant polymer into dimethyl sulfoxide (DMSO). However, this process needs the steps of the reprecipitation, the separation of the resultant solid, and the re-dissolution of this solid, and is therefore unfit for industrial production. In addition, also as to this process, the dealcoholation conversion is so insufficient that it is necessary to keep high temperature for a certain time in order to further advance the reaction in the molding step such as press molding, or that it is necessary to run the reaction in a solution for a long time in order to increase the dealcoholation conversion. Furthermore, this process needs a step of removing the solvent again because the resin as obtained by the dealcoholation reaction is in a solution state. In addition, even if a dealcoholation conversion near 90% can be achieved, and even if the resultant resin provides results satisfactory in some degree with regard to the heat-resistance of the resin, there is still a great demerit in that foam or silver streak occurs in the molded product due to heating in the molding step.
SUMMARY OF THE INVENTION
A. Object of the Invention
An object of the present invention is to provide a production process for a transparent heat-resistant resin, and further, a transparent heat-resistant resin and uses therefor, wherein the production process involves high dealcoholation conversion and a low content of residual volatiles in the resultant resin, and therefore can prevent foam or silver streak from occurring in the molded product, and further, facilitates melt-molding such as injection molding, and is fit for industrial production, and involves good efficiency.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above problems, and as a result, found that the above problems could be all solved if a process comprising the step of running a dealcoholation reaction of a polymer having a hydroxyl group and an ester group in its molecular chain to introduce a lactone ring structure into the polymer to obtain a transparent resin having the heat resistance further comprises the step of running the dealcoholation reaction and a devolatilization treatment simultaneously with each other in the presence of a solvent.
That is to say, a production process for a transparent heat-resistant resin, according to the present invention, comprises the step of running a dealcoholation reaction of a polymer having a hydroxyl group and an ester group in its molecular chain to introduce a lactone ring structure into the polymer to obtain a transparent resin having the heat resistance, and is characterized in that the dealcoholation reaction is run in the presence of a solvent, and further characterized by further comprising a devolatilization step which is carried out jointly with the dealcoholation reaction.
In addition, a transparent heat-resistant resin, according to the present invention, is obtained by a process including the step of running a dealcoholation reaction of a polymer having a hydroxyl group and an ester group in its molecular chain to introduce a lactone ring structure into the polymer, and is characterized by having a dealcoholation conversion of not lower than 90% as determined from a weight loss between 150 and 300° C. in dynamic TG measurement. Furthermore, a transparent heat-resistant resin molding material, according to the present invention, is characterized by comprising this transparent heat-resistant resin according to the present invention. If this transparent heat-resistant resin molding material according to the present invention is molded, a molded product according to the present invention is obtained.
Another transparent heat-resistant resin, according to the present invention, is obtained by a process including the step of running a dealcoholation reaction of a polymer having a hydroxyl group and an ester group in its molecular chain to introduce a lactone ring structure into the polymer, and is characterized by having a yellowness index (YI) of not more than 6 in a 15 weight % chloroform solution. Furthermore, another transparent heat-resistant resin molding material, according to the present invention, is characterized by comprising this transparent heat-resistant resin according to the present invention. If this transparent heat-resistant resin molding material according to the present invention is molded, another molded product according to the present invention is obtained.
Yet another transparent heat-resistant resin, according to the present invention, is obtained by a process including the step of running a dealcoholation reaction of a polymer having a hydroxyl group and
Asano Hideo
Fujioka Kazumi
Haugen Law Firm PLLP
Lipman Bernard
Nippon Shokubai Co. , Ltd.
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