Thermoset composition, method, and article

Abstract

A curable composition includes a functionalized poly(arylene ether), an alkenyl aromatic monomer, an acryloyl monomer, and a polymeric additive effective selected from polystyrene, poly(styrene-maleic anhydride), poly(styrene-methyl methacrylate), polybutene, poly(ethylene-butylene), poly(vinyl ether), poly(vinyl acetate), and combinations thereof. The composition exhibits low shrinkage on curing and improved surface smoothness. It is useful, for example, in the manufacture of automotive body panels.

Description

[0001] Thermoset molding compositions known in the art are generally thermosetting resins containing inorganic fillers and / or fibers. Upon heating, thermoset monomers initially exhibit viscosities low enough to allow for melt processing and molding of an article from the filled monomer composition. Upon further heating, the thermosetting monomers react and cure to form hard resins with high stiffness.[0002] One industrial use of thermoset compositions is the molding of automotive body panels. These panels preferably exhibit high dimensional stability and a smooth as-molded surface. It is also preferred that the dimensions of the molded parts conform closely to those of the molds used to prepare them.[0003] Thermoset compositions based on unsaturated polyester resins and styrene are known to exhibit reduced shrinkage and improved surface properties when they incorporate a so-called low-profile additive, such as a polymethacrylate copolymer. See, for example, V. A. Pattison et al. J. ...

AI Technical Summary

Benefits of technology

[0011] After extensive investigations, the present inventors have characterized and identified polymeric additives that reduce shrinkage on molding and improve as-molded surface characteristics of poly(arylene ether)-containing thermoset compositions.

[0032] In a preferred embodiment, the capped poly(arylene ether) may be prepared by reaction of an uncapped poly(arylene ether) with an anhydride in an alkenyl aromatic monomer as solvent. This approach has the advantage of generating the capped poly(arylene ether) in a form that can be immediately blended with other components to form a curable composition; using this method, no isolation of the capped poly(arylene ether) or removal of unwanted solvents or reagents is required.

[0041] There is no particular limitation on the molecular weight or intrinsic viscosity of the functionalized poly(arylene ether). In one embodiment, the composition may comprise a functionalized poly(arylene ether) having a number average molecular weight up to about 10,000 atomic mass units (AMU), preferably up to about 5,000 AMU, more preferably up to about 3,000 AMU. Such a functionalized poly(arylene ether) may be useful in preparing and processing the composition by reducing its viscosity.

[0042] In another embodiment, the composition may comprise a functionalized poly(arylene ether) having an intrinsic viscosity of about 0.08 to about 0.30 deciliters per gram (dL / g), preferably about 0.12 to about 0.30 dL / g, more preferably about 0.20 to about 0.30 dL / g as measured in chloroform at 25.degree. C. Generally, the intrinsic viscosity of a functionalized poly(arylene ether) will vary insignificantly from the intrinsic viscosity of the corresponding unfunctionalized poly(arylene ether). Specifically, the intrinsic viscosity of a functionalized poly(arylene ether) will generally be within 10% of that of the unfunctionalized poly(arylene ether). These intrinsic viscosities may correspond approximately to number average molecular weights of about 5,000 to about 25,000 ANU. Within this range, a number average molecular weight of at least about 8,000 AMU may be preferred, and a number average molecular weight of at least about 10,000 AMU may be more preferred. Also within this range, a number average molecular weight up to about 20,000 AMU may be preferred. Such a functionalized poly(arylene ether) may provide the composition with a desirable balance of toughness and processability. It is expressly contemplated to employ blends of at least two functionalized poly(arylene ether)s having different molecular weights and intrinsic viscosities.

Problems solved by technology

However, low-profile additives known for polyester thermosets are ineffective in the poly(arylene ether)-containing compositions.

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