Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1991-01-17
1993-07-06
Short, Patricia A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 53, C08G 6391
Patent
active
052254976
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Technical Field of the Invention
The present invention relates to a novel process for the preparation of an elastic polyester comprising an aromatic polyester as a hard segment and an aliphatic polyester as a soft segment.
Background Art
A polyester-polyester type block copolymer comprising hard segments composed of an aromatic polyester such as polybutylene terephthalate and soft segments composed of a polylactone is widely used as a thermoplastic elastomer having excellent tensile strength, tear strength, flexural fatigue resistance and heat resistance for the production of automobile parts, electric and electronic parts and machine parts.
This polyester-polyester block copolymer type elastic polyester is prepared by melt-mixing and reacting a crystalline aromatic polyester with a lactone compound in a reaction vessel, and the preparation processes are known from Japanese Examined Patent Publication No. 48-4116, Japanese Examined Patent Publication No. 52-49037, Japanese Unexamined Patent Publication No. 61-281124, Japanese Unexamined Patent Publication No. 61-283619, Japanese Unexamined Patent Publication No. 61-287922, Japanese Unexamined Patent Publication No. 62-20525, Japanese Unexamined Patent Publication No. 62-27425 and Japanese Unexamined Patent Publication No. 62-53336.
The known processes disclosed in these patent publications have problems, however, in that the reaction time is long and since the aromatic polyester constituting hard segments and the polylactone constituting soft segments are partially rendered random by the ester exchange reaction, only an elastic polyester having large variations of the melting point and mechanical strength is obtained.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to solve the above-mentioned problem and provide a process for the continuous preparation of an elastic polyester having a stable quality.
The inventors of the present invention found that this object can be attained by using a specific extruder as the reaction vessel and continuously supplying and reacting an aromatic polyester and a lactone compound therein.
More specifically, in accordance with the present invention, there is provided a process for the continuous preparation of an elastic polyester, which comprises continuously supplying an aromatic polyester and a lactone compound into an extruder which has (A) a cylinder having a shape of 5.ltoreq.L/D.ltoreq.60 (where L represents the length of the cylinder and D represents the inner diameter of the cylinder) and (B) at least one screw, and wherein (C) the occupancy ratio (V) of the space in the inner volume of the cylinder in the screw-attached state as defined by the following formula is not larger than 70% volume of the cylinder including the screw volume, and reacting the aromatic polyester with the lactone compound while performing melting, delivery and kneading in the extruder, whereby the reaction of the aromatic polyester with the lactone is completed in the extruder and an elastic polyester is continuously prepared.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow chart illustrating one embodiment of the present invention;
FIG. 2 is a side view illustrating a part of a screw kneading unit of a single-screw extruder;
FIG. 3 is a sectional view of a twin-screw extruder used in one embodiment of the present invention;
FIG. 4 is a sectional view showing a part of a screw and cylinder of an extruder in one embodiment of the present invention, which has a structure where the screw makes one reciprocating motion in the axial direction while the screw makes one revolution;
FIG. 5 is a partially cut-out side view showing a self-cleaning type twin-screw extruder used in one embodiment of the present invention;
FIGS. 6(A) and 6(B) are sectional views showing typical shapes of the paddle;
FIG. 7 is a partially cut-out sectional view of a polymerization vessel used for comparison; and
FIG. 8 is a sectional view of a polymerization reactor used for comparison.
TABLE
REFERENCES:
patent: 3254053 (1966-05-01), Fisher
patent: 4500686 (1985-02-01), Kobayashi
patent: 4680345 (1987-07-01), Kobayashi
Ishii Hiromitsu
Yamamoto Shoji
Yamamoto Yoshiyuki
Short Patricia A.
Toray Industries Inc.
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