Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-03-06
2004-09-21
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S09200D, C525S09200D, C525S397000, C525S425000
Reexamination Certificate
active
06794450
ABSTRACT:
BACKGROUND OF INVENTION
The invention relates to a method of enhancing the melt flow characteristics of compositions comprising a compatibilized poly(arylene ether)/polyamide resin blend.
Poly(arylene ether) resins are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of these resins with polyamide resins into compatibilized blends results in additional overall properties such as chemical resistance and high strength. Examples of such compatibilized blends can be found in U.S. Pat. No. 4,315,086 to Ueno, et al; U.S. Pat. No. 4,659,760 to van der Meer; and U.S. Pat. No. 4,732,938 to Grant, et al. The properties of these blends can be further enhanced by the addition of various additives such as impact modifiers, flame retardants, light stabilizers, processing stabilizers, heat stabilizers, antioxidants and fillers.
The physical properties of poly(arylene ether)/polyamide blends make them attractive for a variety of end-use articles in the automotive market, especially for under hood and various exterior components. Many of these components are subjected to a variety of abuses such as impacts and as such require outstanding impact resistance and ductility. Moreover, many of these same articles are preferentially produced using conversion techniques such as injection molding. Some of the desirable applications, for example connectors, have very thin wall sections and therefore require resins that have very low viscosities in order to completely fill the molding tools. Conventional poly(arylene ether)/polyamide blends have inadequate flow properties at the processing temperatures that are needed to minimize the thermal degradation of the resins. Increasing the processing temperature to higher than these temperatures in order to reduce viscosity of the blends results in brittle parts and many surface imperfections in the final part, both of which are unacceptable.
It is therefore apparent that a need continues to exist for compatibilized poly (arylene ether)/polyamide compositions that have improved melt flow yet retain the other attractive physical properties.
SUMMARY OF INVENTION
The needs discussed above have been generally satisfied by the discovery of a thermoplastic composition comprising a compatibilized poly(arylene ether)/polyamide resin blend and a dendritic polyester resin.
In another embodiment, a method of enhancing the melt flow of compatibilized poly(arylene ether)/polyamide resin blends comprises intimately mixing a poly(arylene ether) resin, a polyamide resin, and a compatibilizing agent with a dendritic polyester resin.
Alternatively, a method for enhancing the melt flow of a compatibilized poly (arylene ether)/polyamide resin blend comprises intimately mixing a compatibilized poly(arylene ether)/polyamide resin blend with a dendritic polyester resin.
DETAILED DESCRIPTION
A thermoplastic composition comprises a compatibilized poly(arylene ether)/polyamide resin blend and a dendritic polyester resin. The inclusion of as little as 0.5 weight percent of dendritic polyester resin can increase the melt flow rate of the compatibilized poly(arylene ether)/polyamide resin blend by as much as 100%. Melt flow rate is defined as the mass of plastic melt that flows through an orifice at a defined temperature and load on the plastic melt. The melt flow rate values contained herein were determined according to ASTM method D1238 (same as ISO 1130). Due to the increased melt flow, the thermoplastic composition may be formed into articles with broad ranges of thicknesses by injection molding without degradation of physical properties such as the heat distortion temperature due to thermal degradation.
Compatibilized poly(arylene ether)/polyamide resin blends are produced by combining poly(arylene ether), polyamide and a compatibilizing agent. The term poly (arylene ether) includes polyphenylene ether (PPE) and poly(arylene ether) copolymers; graft copolymers; poly(arylene ether) ether ionomers; and block copolymers of alkenyl aromatic compounds, vinyl aromatic compounds, and poly(arylene ether), and the like; and combinations comprising at least one of the foregoing; and the like. Poly(arylene ether)s per se, are known polymers comprising a plurality of structural units of the formula (I):
wherein for each structural unit, each Q
1
is independently halogen, primary or secondary lower alkyl (e.g., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms, or the like; and each Q
2
is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy, halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms, or the like. Preferably, each Q
1
is alkyl or phenyl, especially C
1-4
alkyl, and each Q
2
is hydrogen.
Both homopolymer and copolymer poly(arylene ether) are included. The preferred homopolymers are those containing 2,6-dimethylphenylene ether units. Suitable copolymers include random copolymers containing, for example, such units in combination with 2,3,6-trimethyl-1,4-phenylene ether units or copolymers derived from copolymerization of 2,6-dimethylphenol with 2,3,6-trimethylphenol. Also included are poly(arylene ether) containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes, as well as coupled poly(arylene ether) in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two poly(arylene ether) chains to produce a higher molecular weight polymer. Poly (arylene ether)s further include combinations comprising at least one of the above.
The poly(arylene ether) generally has a number average molecular weight of about 3,000-40,000 atomic mass units (amu) and a weight average molecular weight of about 20,000-80,000 amu, as determined by gel permeation chromatography. The poly(arylene ether) may have an intrinsic viscosity of about 0.10 to about 0.60 deciliters per gram (dl/g), preferably about 0.29 to about 0.48 dl/g, as measured in chloroform at 25° C. It is also possible to utilize a high intrinsic viscosity poly(arylene ether) and a low intrinsic viscosity poly(arylene ether) in combination. Determining an exact ratio, when two intrinsic viscosities are used, will depend somewhat on the exact intrinsic viscosities of the poly(arylene ether) used and the ultimate physical properties that are desired.
Poly(arylene ether) is typically prepared by the oxidative coupling of at least one monohydroxyaromatic compound such as 2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generally employed for such coupling; they typically contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.
Useful poly(arylene ether) also include those which comprise molecules having at least one aminoalkyl-containing end group. The aminoalkyl radical is typically located in an ortho position to the hydroxy group. Products containing such end groups may be obtained by incorporating an appropriate primary or secondary monoamine such as di-n-butylamine or dimethylamine as one of the constituents of the oxidative coupling reaction mixture. Also frequently present are 4-hydroxybiphenyl end groups, typically obtained from reaction mixtures in which a by-product diphenoquinone is present, especially in a copper-halide-secondary or tertiary amine system. A substantial proportion of the polymer molecules, typically constituting as much as about 90% by weight of the polymer, may contain at least one of said aminoalkyl-containing and 4-hydroxybiphenyl end groups.
It will be apparent to those skilled in the art from the foregoing that the contemplated poly(arylene ether) include all those presently known, irrespective of variations in structural units or ancillary chemical features. Poly(arylene ether) is
General Electric Company
Short Patricia A.
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