Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-01-27
1998-06-16
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523205, 523206, C08K 904
Patent
active
057671745
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a vinyl chloride resin composition which is excellent in moldability and which provides a molded product excellent in strength, impact strength, elastic modulus, moisture resistance and surface appearance.
BACKGROUND ART
A vinyl chloride resin and a vinyl chloride resin composition obtained by blending a plasticizer to a vinyl chloride resin have such merits that they are relatively excellent in mechanical strength, and they can be produced at a low cost. Accordingly, as resin materials for producing general purpose molded products, they are used for various purposes such as architectural parts, industrial parts and parts of electrical machinery and apparatus. However, they have such demerits that for some purposes, they are poor in heat resistance, mechanical strength, dimensional stability and thermal expansion.
To overcome these demerits, a study is being made to improve properties of a resin by alloying polymers having properties different from each other. For example, there are various proposals for alloying a vinyl chloride resin and an olefin resin (JP-B-60-36178, JP-A-63-604039, JP-A-1-165640, JP-A-2-199127, JP-A-2-199128, JP-A-2-199129 and the like). However, the polymer alloy thus obtained is poor in elastic modulus and heat resistance, since it contains an olefin resin.
On the other hand, it is known to incorporate glass fibers to a vinyl chloride resin to strengthen and improve the properties of the vinyl chloride resin. By this method, the rigidity and tensile strength can be fairly improved, but the impact strength is often lowered.
Particularly, since a vinyl chloride resin is poorer in melt flowability than other thermoplastic resins, the wettability with glass fibers is unsatisfactory, glass fibers are not dispersed evenly, and the melt flowability of the vinyl chloride resin wherein glass fibers are blended is extremely low. As a result, there were such demerits as breaking down of glass fibers during kneading, heat deterioration of the resin, and particularly a poor impact strength. Further, glass fibers come up to the surface of a molded material, and the surface therefore becomes coarse. Accordingly, surface appearance becomes inferior. Thus, satisfactory properties could not be easily obtained.
To overcome the above demerits, there are, for example, such proposals as (1) raising the molding temperature and (2) adding a lubricant, a surface modifying agent, or a resin miscible with a vinyl chloride resin having an excellent melt flowability, such as an ethylene-vinyl acetate copolymer, an ethylene-vinylchloride copolymer or chlorinated polyethylene, to lower the viscosity of a vinyl chloride resin, as a result, to improve the dispersibility and the wettability with glass fibers.
However, the above proposal (1) wherein the molding temperature is raised, is not practical, because a vinyl chloride resin originally has a molding temperature very close to the decomposition temperature, and it is therefore necessary to control the temperature strictly. Further, when adopting the above proposal (1), only a little rise of temperature makes the resin decomposed, and the mechanical strength of the molded material will be low.
The above proposal (2) wherein a resin is added so that the viscosity of a vinyl chloride resin is lowered, needs an addition of a large amount of resin to get a satisfactory level of viscosity, and it substantially changes the original characteristic of a vinyl chloride resin.
Therefore, the above proposal (2) has such demerits as the loss of such merit that the mechanical strength of a resin is improved by adding glass fibers.
Further, it is known that glass fibers are added from a vent hole or a die of an extruder to prevent the glass fibers from being broken down during molding and to improve the mechanical strength of a molded product. In accordance with this method, the glass fibers are not broken down, but the wetting between the resin and the glass fibers is not sufficient. Accordingly, this method has demerits su
REFERENCES:
patent: 5047263 (1991-09-01), Glemet
patent: 5258232 (1993-11-01), Summers et al.
Arai Shigeharu
Kaida Yuriko
Kozawa Shigeyuki
Min Kyon Hun
Nakagawa Hideki
Asahi Fiber Glass Company, Ltd.
Asahi Glass Company Ltd.
Aylward D.
Marquis Melvyn I.
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