Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-07-02
2003-05-13
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C528S388000
Reexamination Certificate
active
06562900
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a production process for a polyarylene sulfide (hereinafter abbreviated as PAS) resin. More specifically, it relates to a production process for a PAS resin having a high molecular weight and an excellent heat stability, a PAS resin having such characteristics, a resin composition comprising this PAS resin and an inorganic filler and a molded article comprising this resin composition.
RELATED ART
Polyarylene sulfide, especially polyphenylene sulfide is known as an engineering plastic which is excellent in a mechanical strength and a heat resistance and which has good electric characteristics and a high rigidity, and it is widely used as various materials such as base materials for electric and electronic equipment parts. In particular, articles of a resin composition comprising polyphenylene sulfide and an inorganic filler are used for various uses.
In a conventional production process in which a dihalogen aromatic compound such as p-dichlorobenzene is reacted with alkaline metal sulfide in a polar solvent such as N-methyl-2-pyrrolidone to thereby obtain PAS, alkaline metal sulfide is insoluble in the polar solvent, and therefore a prescribed amount of water is added. In this case, alkaline metal sulfide is dissolved in the solvent by virtue of the presence of water, and a part thereof is subjected to hydrolysis and changed to metal hydrosulfide. This alkaline metal hydrosulfide works as a chain-transfer agent, so that a molecular weight of PAS is inhibited from going up or a terminal of the polymer is turned into —SH. This brings about the problem that PAS having an inferior heat stability is produced.
In order to solve this problem, provided are a method in which water is added and then pre-polymerization is carried out at a low temperature to thereby turn PAS into a high polymer (Japanese Patent Application Laid-Open No. 9228/1989) and a method in which a small amount of water is added and then pre-polymerization is carried out to thereby raise a conversion of alkaline metal sulfide, followed by adding water to carry out polycondensation (Japanese Patent Application Laid-Open No. 7332/1986). However, they are not satisfactory in terms of obtaining PAS having a high molecular weight and an excellent heat stability.
SUMMARY OF THE INVENTION
The present invention has been made in light of the problem described above, and an object thereof is to provide a production process for PAS having a high molecular weight and an excellent heat stability.
Another object of the present invention is to provide PAS having a high molecular weight and an excellent heat stability.
Intensive investigations repeated by the present inventors have resulted in finding that in a process for producing polyarylene sulfide by reacting a dihalogen aromatic compound with metal sulfide in a polar solvent, all or a part of water required for the reaction is added on a condition that the reaction system is 100° C. or higher, whereby the objects described above can be achieved. Thus, they have completed the present invention.
That is, the present invention comprises the following essential points.
(1) Polyarylene sulfide which is reduced in an intrinsic viscosity [&eegr;] by 0.05 deciliter/g or less at 206° C. when added to an N-methyl-2-pyrrolidone solvent is the polyarylene sulfide of an amount equivalent to that of the solvent and it is maintained at 265° C. for 8 hours.
(2) The polyarylene sulfide as described in the above item (1), wherein the polyarylene sulfide is a homopolymer or a copolymer comprising 70 mole % or more of a paraphenylene sulfide unit as a repeating unit.
(3) The polyarylene sulfide as described in the above item (2), wherein the polyarylene sulfide comprises a copolymerization structural unit selected from a metaphenylene sulfide unit, an orthophenylene sulfide unit, a p,p′-diphenylene ketone sulfide unit, a p,p′-diphenylene sulfone sulfide unit, a p,p′-biphenylene sulfide unit, a p,p′-diphenylene ether sulfide unit, a p,p′-diphenylenemethylene sulfide unit, a p,p′-diphenylenecumenyl sulfide unit and a naphthyl sulfide unit.
(4) A production process for polyarylene sulfide by reacting a dihalogen aromatic compound with metal sulfide in a polar solvent, wherein all or a part of water required for the reaction is added on a condition that the reaction system is 100° C. or higher to obtain the polyarylene sulfide as described in the above item (1).
(5) The production process as described in the above item (4), wherein the dihalogenoaromatic compound is selected from dihalogenobenzenes, dihalogenoalkyl-substituted benzenes or dihalogenocycloalkyl-substituted benzenes, dihalogenoaryl-substituted benzenes, dihalogenobiphenyls and dihalogenonaphthalenes.
(6) The production process as described in the above item (4), wherein water is added on a condition that the reaction system is 100 to 270° C.
(7) The production process as described in the above item (4), wherein a use amount of the dihalogen compound is 0.8 to 1.2 in terms of a mole ratio based on the metal sulfide.
(8) The production process as described in the above item (4), wherein a use amount of water is 0.05 to 4.0 in terms of a mole ratio based on the metal sulfide.
(9) A polyarylene sulfide resin composition comprising 20 to 90% by weight of the polyarylene sulfide as described in the above item (1) and 80 to 10% by weight of an inorganic filler.
(10) An article prepared by molding the polyarylene sulfide resin composition as described in the above item (9).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention shall specifically be explained below.
1. Polyarylene Sulfide (PAS)
The PAS of the present invention is a polyarylene sulfide resin in which polyarylene sulfide (PAS) is reduced in an intrinsic viscosity [&eegr;] by 0.05 deciliter/g or less, preferably 0.03 deciliter/g or less and particularly preferably 0.02 deciliter/g or less at 206° C. when added to an N-methyl-2-pyrrolidone(NMP) solvent is the polyarylene sulfide of an amount equivalent to that of the solvent and it is maintained at 265° C. for 8 hours. The above resin is excellent in a heat stability and therefore can be used for various severe uses.
A method for evaluating a heat stability in the present invention is suitably a method in which a mixture of PAS and NMP is used and this mixture is maintained at a high temperature (265° C.) for 8 hours to observe a change in an intrinsic viscosity [&eegr;]. In this case, a mixing proportion of PAS to NMP is optional, but in order to elevate the reproducibility, both are mixed in an equivalent amount, for example, each 2.5 g. Taking a solubility of this kind of the resin into consideration, the intrinsic viscosity [&eegr;] is conveniently expressed by the value at 206° C.
The PAS produced by the production process of the present invention is, for example, a polymer having 70 mole % or more of a repeating unit represented by a structural formula —Ar—S— (wherein A is an arylene group). A representative thereof includes PPS having 70 mole % or more of a repeating unit represented by the following structural formula
(wherein R
1
represents a substituent selected from an alkyl group having 6 or less carbon atoms, an alkoxy group, a phenyl group, a carboxylic acid/metal salt group, an amino group, a nitro group and a halogen atom such as fluorine, chlorine and bromine; m represents an integer of 0 to 4; and n represents an average degree of polymerization and falls in a range of 10 to 200) or PPS represented by the following structural formula (II):
(wherein n is synonymous with n in Formula (I).
In general, known according to a production process thereof are PAS which is substantially linear and has a molecular structure having no branched and cross-linking structures and PAS of a molecular structure having branched and cross-linking structures. The production process of the present invention is effective for either type thereof. The PAS includes a homopolymer or a copolymer e
Bando Toru
Okamoto Masaya
Senga Minoru
Dawson Robert
Petroleum Energy Center
Zimmer Marc S.
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