Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
2000-02-02
2002-02-26
Lovering, Richard D. (Department: 1712)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C523S468000, C524S251000, C524S255000, C525S392000, C525S905000
Reexamination Certificate
active
06350514
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to compositions of thermoplastic blends. More particularly, the invention relates to thermoplastic blends comprising a poly(arylene ether) and a poly(alkenylaromatic) compound.
Thermoplastic resins have been used in recent years as a replacement for metal in the interior parts of automobiles, such as the instrument panels, top covers and arm rests. Recently there has been a desire for materials with exceptional stability of mechanical properties during the lifetime of the vehicle. This desire is motivated by safety precaution, in general, and particularly by requirements for seamless instrument panels for use with air bags. Further requirements of the thermoplastic resin are that it must have low odor and emission and must adhere to polyurethane foam, to which the thermoplastic is bonded to form an automobile interior part.
U.S. Pat. No. 5,910,526 to Chu et al. teaches the addition of terpene phenol resins to a thermoplastic to promote moldability and adhesion to polyurethane foam. However, the use of such terpene phenol resins has the undesired effect of reducing the thermal stability of the finished thermoplastic article. U.S. Pat. No. 5,756,196 to Chao et al. describes thermoplastic compositions comprising polyphenylene ethers, poly(alkenylaromatic) compounds, and primary or secondary aliphatic amine compounds. Compared to formulations without the aliphatic amine compound, these compositions exhibit improved surface adhesion to polyurethane foam. However, there is a desire for adhesion-promoting materials with higher inherent stability, lower corrosivity, and lower volatility to facilitate use at high compounding temperatures. There is also a desire for adhesion-promoting materials that can be handled as solids.
There is therefore a need for thermoplastic resins that exhibit improved thermal stability and processing characteristics while maintaining good adhesion to polyurethane foam.
BRIEF SUMMARY OF THE INVENTION
Good adhesion to polyurethane foam and improved thermal stability is provided by a thermoplastic composition comprising: (a) a poly(arylene ether) at about 20 to about 80 weight percent; (b) a poly(alkenylaromatic) material at about 20 to about 80 weight percent; and (c) an aromatic amine at about 0.1 to about 25 weight percent, based on the weight of the entire composition.
DETAILED DESCRIPTION OF THE INVENTION
Good thermal stability and adhesion to polyurethane foam are provided by a thermoplastic composition comprising: (a) a poly(arylene ether) at about 20 to about 80 weight percent; (b) a poly(alkenylaromatic) material at about 20 to about 80 weight percent; and (c) an aromatic amine at about 0.1 to about 25 weight percent, based on the weight of the entire composition.
Although all conventional poly(arylene ether)s can be employed with the present invention, polyphenylene ethers (“PPE”) are preferred. Poly(arylene ether)s per se, are known polymers comprising a plurality of structural units of the formula:
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, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q
2
is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q
1
. 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)s 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)s containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes, as well as coupled poly(arylene ether)s 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 of the present invention further include combinations of any of the above.
The poly(arylene ether)s generally have a number average molecular weight of about 3,000 to about 40,000 and a weight average molecular weight of about 20,000 to about 80,000, as determined by gel permeation chromatography. The poly(arylene ether) generally has 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, all 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.
The 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.
Particularly useful poly(arylene ether)s for many purposes are 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 weight percent 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 poly(arylene ether) contemplated for use in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features.
The poly(alkenylaromatic) compound employed in the thermoplastic resinous substrate composition includes homopolymers and copolymers of such compounds as styrene, &agr;-methylstyrene, 4-methylstyrene, dibromostyrene, and the like, and combinations comprising at least one of these compounds with, styrene generally preferred. Particularly preferred are conventional rubber-modified polystyrenes, sometimes designated “high impact polystyrene” or “HIPS”. Also highly preferred are non-impact modified polystyrenes (often referred to as crystal clear polystyrene or ccPS), such as the material sold by Elf Atochem as Lacqrene 1810, or the material sold by Nova Chemicals as Crystal 209.
It is known that poly(arylene ether)s and poly(alkenylaromatic) materials are miscible in all proportions. While poly(arylene ether) and poly(alkenylaromatic) material blends containing any proportion of the two resins may be employed in the invention, it is preferred that the poly(arylene ether) be present in amounts of about 20 to about 80 weight percent of the total composition, preferably about 20 to about 60 weight percent of the total composition, and more preferably about 25 to about 50 weight percent of the total composition. The poly(alkenylaromatic) material can be present in an amount of about 20 to about 80 weight percent of the total composition,
General Electric Co.
Lovering Richard D.
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