Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1985-06-13
1987-02-03
Jacobs, Lewis T.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
524539, C08L 6702
Patent
active
046409610
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a resin composition comprising a wholly aromatic copolyester and a polyarylate, capable of providing molded articles having excellent heat resistance and impact resistance and having a good appearance.
BACKGROUND ART
A heat-fusible wholly aromatic copolyester represented by the general formula: ##STR2## (wherein d, e, and f are not equal to O and e/f is from 0.90 to 1.10, and n is 0 or 1) has high heat resistance and exhibits excellent fluidity at suitable processing temperatures and thus, it is expected to find wide use in the fabrication of, for example, electric or electronic parts.
This wholly aromatic copolyester, however, has a disadvantage in that when injection molded, since its molding temperature is high, its melt viscosity varies markedly with even a slight change in molding temperature, and it readily undergoes orientation; thus it produces only molded articles having a bad appearance due to uneven flow marks. Further, in connection with the physical properties of its molded articles, they have a low impact strength and are brittle. Thus the wholly aromatic copolyester is difficult to put into practical use as a structural material even though it has excellent heat resistance.
In order to improve the appearance of molded articles, various attempts have heretofore been made. As the methods for improving the marked change of melt viscosity by the molding temperature, there is a method for blending with resins having a lower temperature dependency.
For example, a method of blending with polyethylene terephthalate or polycarbonate is such a method.
However, if the wholly aromatic copolyester is mixed with polyethylene terephthalate or polycarbonate, granulated, and molded in a temperature range where the wholly aromatic copolyester is uniformly melted, the polyethylene terephthalate or polycarbonate readily undergoes thermal decomposition. On the other hand, if they are treated in a temperature range where these resins can be melted stably, the fluidity of the wholly aromatic copolyester is not sufficient to enable the whole of the composition to become a uniform dispersion.
Further, as a method for increasing the impact strength of the molded articles, there is the method of blending with rubbers. In this case, however, the same problems as encountered in the blending with polyethylene terephthalate or polycarbonate occur.
Moreover, both the above-described methods are undesirable because they cause a serious reduction in heat resistance of the resulting molded articles.
DISCLOSURE OF THE INVENTION
As the result of extensive investigations to overcome the above-described problems, the present inventors have found that blending of a wholly aromatic copolyester with a polyarylate permits the production of a composition from which molded articles having a good appearance and a high impact strength can be produced, without causing a serious reduction in the excellent heat resistance of the wholly aromatic copolyester.
That is, the present invention relates to a resin composition comprising from 60 to 97% by weight of a wholly aromatic copolyester and from 3 to 40% by weight of a polyarylate.
The wholly aromatic copolyester that is used in the present invention is a heat-fusible wholly aromatic copolyester represented by the general formula: ##STR3## (wherein d, e, and f are not equal to O and e/f is from 0.90 to 1.10, and n is 0 or 1) and it is preferred that ##STR4## respectively and d/e is from 1.5 to 3.5 because the heat resistance is high and heat-fusibility is good. As methods for polymerization of such aromatic copolyesters there are methods as described in Japanese Patent Application Kokai Nos. 104932/81 and 44622/82, but the present invention is not intended to be limited thereto.
The polyarylate that is used in the present invention is a polyarylate prepared from a mixture of isophthalic acid or a functional derivative thereof and terephthalic acid or a functional derivative thereof and a bisphenol represented by the general formula: ##S
REFERENCES:
patent: 4267289 (1981-05-01), Froix
patent: 4379892 (1983-04-01), Ueno
patent: 4386174 (1983-05-01), Cogswell
patent: 4414365 (1985-11-01), Sugimoto
Asai Kuniaki
Kagiya Kei
Saito Teruo
Suzuki Yasuro
Jacobs Lewis T.
Short Patricia A.
Sumitomo Chemicial Company, Limited
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