Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From sulfur-containing reactant
Reexamination Certificate
2002-03-15
2003-05-20
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From sulfur-containing reactant
C528S383000, C528S387000, C528S489000
Reexamination Certificate
active
06566488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel polyarylene sulfide, a polyarylene sulfide resin composition comprising it, injection moldings of the composition, and a method for producing the polyarylene sulfide. Precisely, the invention relates to a resin composition comprising a polyarylene sulfide and glass fibers, of which the chloroform soluble content is at most 0.5% by weight and which therefore has much balanced properties of fluidity, flexural strength and impact resistance, and also to injection moldings of the composition for car parts. Further, the invention relates to a novel polyarylene sulfide in which the content of low-molecular-weight components is reduced, and to a method for producing it.
2. Description of the Related Art
Polyphenylene sulfide is a typical one of polyarylene sulfides, and is much used for parts for cars and electric and electronic appliances, as having the advantages of good heat resistance, flame retardancy, rigidity, solvent resistance and electric insulation.
However, for parts to be used in severe conditions, for example, for those for car engines, conventional resin compositions comprising a composite of polyphenylene sulfide with glass fibers are still defective in mechanical strength.
One known means for overcoming the problem is to increase the molecular weight of polyphenylene sulfide for enhancing the mechanical strength of the resin compositions. In this case, however, the fluidity of the resin compositions is lowered and therefore the moldability thereof is degraded. Given that situation, it is desired to develop some technique for enhancing the mechanical strength of the resin compositions without lowering the fluidity thereof.
SUMMARY OF THE INVENTION
The present invention has its object to provide a polyarylene sulfide resin composition having well balanced mechanical strength with its fluidity being not reduced, and its injection moldings, and also to provide a novel polyarylene sulfide in which the content of low-molecular-weight components is reduced, and a method for producing it.
We, the present inventors have assiduously studied the subject matter as above, and, as a result, have completed the invention which is as follows:
[1] A polyarylene sulfide resin composition comprising (A) from 30 to 80% by weight of a polyarylene sulfide and (B) from 20 to 70% by weight of an inorganic filler, of which the chloroform soluble content is at most 0.5% by weight relative to the polyarylene sulfide in the composition.
[2] Car parts as produced through injection molding of the polyarylene sulfide resin composition of [1].
[3] A polyarylene sulfide having a chloroform soluble content of at most 0.5% by weight and having an inherent viscosity, &eegr;inh, of from 0.05 to 0.4.
[4] A method for producing a polyarylene sulfide by reacting a dihalogenoaromatic compound with lithium sulfide in an aprotic organic solvent, which is characterized by adding from 21 to 100 mol %, relative to the starting lithium sulfide, of lithium hydroxide to the reaction system.
[5] The method for producing a polyarylene sulfide of [4], which is characterized by two-stage polymerization comprising a prepolymerization step of putting a part of the necessary amount of the starting dihalogenoaromatic compound into the reaction system and a final polycondensation step of adding the remaining part of the starting dihalogenoaromatic compound to the reaction mixture that contains the prepolymer formed in the previous step, or by multi-stage polymerization of repeating the two steps.
[6] A method for producing a polyarylene sulfide by putting a sulfur compound and a dihalogenoaromatic compound into a mixture containing lithium hydroxide in an aprotic organic solvent, which comprises;
(a) a step of putting a liquid or gaseous sulfur compound into a mixture containing lithium hydroxide in an aprotic organic solvent to lead direct reaction between the sulfur compound and lithium hydroxide,
(b) a step of controlling the sulfur content of the resulting reaction mixture,
(c) a step of controlling the lithium hydroxide content of the reaction mixture to fall between 21 and 100 mol % of lithium sulfide therein, and
(d) a step of putting a dihalogenoaromatic compound into the reaction mixture to lead polycondensation of the compound.
[7] The method for producing a polyarylene sulfide of [6], which is characterized by two-stage polymerization comprising (e1) a prepolymerization step of putting the starting dihalogenoaromatic compound into the reaction mixture and (e2) a final polycondensation step of further putting the starting dihalogenoaromatic compound into the reaction mixture that contains the prepolymer formed in the previous step, or by multi-stage polymerization of repeating the two steps.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the invention are described below.
Polyarylene Sulfide Resin Composition:
One aspect of the invention is to provide a polyarylene sulfide resin composition comprising (A) from 30 to 80% by weight, preferably from 50 to 70% by weight, more preferably from 55 to 65% by weight of a polyarylene sulfide and (B) from 20 to 70% by weight, preferably from 30 to 50% by weight, more preferably from 35 to 45% by weight of an inorganic filler, of which the chloroform soluble content is at most 0.5% by weight, preferably at most 0.4% by weight, more preferably at most 0.3% by weight relative to the polyarylene sulfide in the composition.
In the composition, if the amount of the inorganic filler is larger than 70% by weight, the fluidity of the composition is reduced; but if smaller than 20% by weight, the dimension stability of the composition is degraded. Preferably, the resin composition contains a coupling agent. Where the inorganic filler to be in the resin composition is previously subjected to coupling treatment, the amount of the coupling agent to be added to the resin composition may be suitably determined depending on the degree of the pre-coupling treatment of the inorganic filler. If the pre-coupling treatment of the inorganic filler is satisfactory, any additional coupling agent will be unnecessary for the resin composition. However, when the inorganic filler is a non-treated one, from 0.1 to 3.0 parts by weight, relative to 100 parts by weight of the polyarylene sulfide resin (A) in the composition, of a coupling agent maybe added to the composition.
Too much coupling agent over 3.0 parts by weight, if added to the resin composition, will cancel the capabilities of the inorganic filler in the composition. On the other hand, however, if the amount of the coupling agent added is smaller than 0.1 parts by weight, the mechanical strength of the composition will be reduced. If the chloroform soluble content of the resin composition that contains an inorganic filler is larger than 0.5% by weight, the balance of fluidity and mechanical strength of the composition is poor.
The inorganic filler for use in the invention includes, for example, glass fibers, carbon fibers, aramide fibers, potassium titanate whiskers, silicon carbide whiskers, mica ceramic fibers, wollastonite, mica, talc, silica, alumina, kaolin, clay, silica-alumina, carbon black, calcium carbonate, titanium oxide, lithium carbonate, molybdenum disulfide, graphite, iron oxide, glass beads, calcium phosphate, calcium sulfate, magnesium carbonate, magnesium phosphate, silicon nitride, hydrotalcite, etc. One or more of these inorganic fillers may be used either singly or as combined. Of those, especially preferred are glass fibers.
Glass fibers for use in the invention are not specifically defined, and may be any of alkali glass, low-alkali glass or non-alkali glass fibers. The fiber length preferably falls between 0.1 and 8 mm, more preferably between 0.3 and 6 mm; and the fiber diameter preferably falls between 0.1 and 30 &mgr;m, more preferably between 0.5 and 25 &mgr;m. If the fiber length is smaller than 0.1 mm, the reinforci
Bando Toru
Okamoto Masaya
Idemitsu Kosan Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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