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
1993-01-29
2001-10-30
Sanders, Kriellion A. (Department: 1714)
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...
C524S494000
Reexamination Certificate
active
06310130
ABSTRACT:
The present invention relates to compositions based on polyphenylene sulphide. It relates more precisely to compositions containing a polyphenylene sulphide with improved electrical properties.
Polyphenylene sulphide (referred to hereinafter briefly as PPS) exhibits an excellent heat stability and a very good chemical resistance which make it a choice material for the moulding of components which can be employed especially in electrical and electronic applications and in the motor vehicle industry.
In demanding electrical and electronic applications (circuit breakers, multipole rods, breaker bulbs etc.), however, a material must be available which combines heat resistance with a good compromise of two electrical properties which are the tracking current resistance and arc resistance.
Attempts have already been made to attain this objective by proposing compositions based on PPS containing magnesium hydroxide and, optionally, glass fibres (Japanese Patent Application (Kokai) published under number 89-318068 (Ube Industries)).
While these compositions exhibit a good heat resistance and a good arc resistance, their tracking current resistance is insufficient.
The invention aims to provide PPS-based compositions exhibiting at the same time, at a sufficient level, a heat resistance, a tracking current resistance and an arc resistance.
To this end, the present invention relates to compositions containing, per 100 parts by weight of polyphenylene sulphide: 10 to 300 parts by weight of a polyamide and 20 to 350 parts by weight of a metal hydroxide the main constituent of which is magnesium hydroxide.
The polyphenylene sulphide (PPS) present in the compositions according to the invention is a polymer containing at least 70 mol %, preferably at least 90 mol %, of p-phenylene sulphide repeat units of formula
The PPSs containing at least 70 mol % of p-phenylene sulphide repeat units impart sufficient heat stability and chemical resistance to the compositions according to the invention. Less than 30 mol % of the repeat units present in the PPS may be chosen from those which have the structural formulae below:
Processes for the manufacture of the PPSs which can be applied according to the invention are well known. All of them can be employed. A process comprises heating an alkali metal sulphide, in most cases sodium sulphide hydrate, in a polar solvent to remove the water of hydration therefrom, followed by the addition of a di-halogenated aromatic compound, in particular p-dichloro-benzene, and polymerisation at a higher temperature (see, for example, patent U.S. Pat. No. 3,354,129 (Phillips Petroleum)). The molecular weight of the PPS obtained can be increased in a known manner by oxidative posttreatment resulting in branched products or by addition of known agents for increasing the molecular weight (esters, anhydrides, alkali metal carboxylates and sulphonates, etc.) to the polycondensation mixture, resulting in linear products of high molecular weight.
The molecular weight of the PPS which can be employed according to the invention can vary within wide measures. It is generally such that the melt index of the PPS is between 5 g/10 min and 10,000 g/10 min, preferably between 10 g/10 min and 500 g/10 min, determined according to ASTM standard D 1238-74 T, at a temperature of 315° C. under a 5-kg load).
The PPS which can be employed according to the invention may contain conventional additives in quantities which cannot be detrimental to the properties of the compositions according to the invention. By way of such additives there may be mentioned in particular: antioxidants and heat stabilisers such as, for example, hindered phenols, thioesters and phosphites, anti-UV agents such as, for example, resorcinol, benzotriazole and benzophenone, flame-retardant agents such as, for example, antimony salts, aryl chlorophosphates and chlorinated paraffins, lubricants such as, for example, graphite, molybdenum disulphide and silicones, corrosion inhibitors such as, for example, alkali metal carbonates, pigments such as, for example, titanium dioxide and zinc sulphide, processing agents such as, for example, aromatic esters of phosphoric acid and microtalc, agents for controlling the degree of crosslinking such as, for example, peroxides, crosslinking accelerators such as, for example, metal salts of thiophosphinic acid, cross-linking inhibitors such as, for example, dialkyltin dicarboxylates, impact strength improvers such as, for example, elastomeric copolymers derived from olefins and glycidyl esters of alpha,beta-unsaturated carboxylic acids, and the like.
The compositions according to the invention also contain a polyamide (called PA hereinafter). This poly-amide is generally chosen from PAs derived from, on the one hand, aliphatic, alicyclic and aromatic amines and, on the other hand, aliphatic, alicyclic and aromatic dicarboxylic acids.
Examples of amines which can be employed are hexamethylenediamine, decamethylenediamine, dodeca-methylenediamine, 2,2,4- and 2,4,4-trimethyl-hexamethylenediamines, 1,3- and 1,4-bis(aminomethyl)-cyclohexanes, bis(p-aminocyclohexylmethane), m-xylylenediamine and p-xylylenediamine.
Examples of acids which can be employed are adipic, suberic, sebacic, glutaric, azelaic, cyclohexane-dicarboxylic, isophthalic and terephthalic acids.
They may also be PAs derived from the halides or dialkyl esters of these acids, aminocarboxylic acids such as, for example, 6-aminocaproic, 6-aminocaprylic, 6-aminolauric, 11-aminoundecanoic and 12-aminododecanoic acids, or else lactams derived from these acids, such as, for example, &egr;-caprolactam and &ohgr;-dodecalactam.
These PAs may be derived from more than one amine or more than one acid; mixtures of different PAs can also be employed.
Examples of PAs which can be employed are polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polycapramide (nylon 6) and polydodecanamide (nylon 12), as well as the PAs obtained by reaction of condensation of m-xylylenediamine with adipic acid (PAMXD6).
Preferred PAs are nylon 66 and PAMXD6.
The compositions according to the invention generally contain from 10 to 300 parts by weight of PA per 100 parts by weight of PPS, preferably from 25 to 250 parts by weight of PA per 100 parts by weight of PPS.
When it is desirable that the PPS should form the continuous phase of the mixture of PPS and PA, for example with the aim of maintaining the heat resistance of the compositions according to the invention at higher values, the latter generally contain from 25 to 95 parts by weight of PA per 100 parts by weight of PPS, preferably from 35 to 80 parts by weight of PA per 100 parts by weight of PPS.
The compositions according to the invention also contain a metal hydroxide in which the main constituent is magnesium hydroxide. “Metal hydroxide” is hereinafter intended to denote those in which the main constituent is magnesium hydroxide (called more simply magnesium hydroxide hereinafter, reference being made only to its main constituent), that is to say compounds containing more than 50% by weight of Mg(OH)
2
, preferably more than 90% by weight of Mg(OH)
2
, other hydroxides which may be present being, for example, calcium hydroxide, aluminium hydroxide and barium hydroxide, or mixtures thereof. It is possible to employ a natural magnesium hydroxide such as brucite or nemalite, or a synthetic magnesium hydroxide obtained, for example, by electrolysis of a magnesium salt or by precipitation of a magnesium salt using potassium hydroxide or sodium hydroxide. This metal hydroxide may be in the form of powder, granules or fibres. Good results are obtained when the metal hydroxide consists essentially of magnesium hydroxide.
The compositions according to the invention generally contain from 20 to 350 parts by weight of metal hydroxide per 100 parts by weight of PPS, preferably from 50 to 200 parts by weight per 100 parts by weight of PPS. The best results are obtained when the said compositions contain from 75 to 150 parts by weight of metal hydroxide per 100 parts by weight of PP
Dubois Michel
Guyot Béatrice
Thommeret Richard
Sanders Kriellion A.
Schnelller Marina V.
Solvay S.A.
Venable
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