The present invention relates to a composition comprising a polyarylene ether and a dispersible reactive solvent. Polyarylene ethers (PAEs) are a class of thermoplastic resins with excellent mechanical and electrical properties, heat resistance, flame retardancy, low moisture absorption, and dimensional stability. These resins are widely used in automobile interiors, particularly instrument panels, and electrical as well as electronic applications.
PAEs are very difficult to process (for example, by injection molding) as a result of their high melt viscosities and their high processing temperature relative to their oxidative degradation temperature. Consequently, PAEs are commonly blended with compatible polymers such as polystyrene (WO 97/21771 and U.S. Pat. No. 4,804,712); polyamides (U.S. Pat. No. 3,379,792); polyolefins (U.S. Pat. No. 3,351,851); rubber-modified styrene resins (U.S. Pat. Nos. 3,383,435 and 3,959,211, and Ger. Offen. No. 2,047,613); and mixtures of polystyrene and polycarbonate (U.S. Pat. Nos. 3,933,941 and 4,446,278). Unfortunately, improvements in processing have generally been obtained at the expense of flexural modulus, flexural strength, or heat distortion temperature.
Epoxy resins have also been investigated as a reactive solvent for the PAE. (See Venderbosch, R. W., "Processing of Intractable Polymers using Reactive Solvents," Ph.D. Thesis, Eindhoven (1995); Vanderbosch et al., Polymer, Vol. 35, p. 4349 (1994); Vanderbosch et al., Polymer, Vol. 36, p. 1167 (1995a); and Vanderbosch et al., Polymer, Vol. 36, p. 2903 (1995b)). In this instance, the PAE is first dissolved in an epoxy resin to form a solution that is preferably homogeneous. An article is then shaped from the solution, and the solution is cured at elevated temperatures, resulting in a phase separation that can give a continuous PAE phase with epoxy domains interspersed therein. The properties of the finished article are primarily determined by the PAE; however, the use of an epoxy resin as a reactive solvent for the PAE is not practical in a continuous melt process like injection molding because the epoxy resin needs a curing agent to set. The curing agent will, over time, accumulate in the injection molding barrel, thereby fouling the machine. Furthermore, the cure and subsequent phase separation has to take place at at least 150.degree. C., which is impractical in a molder environment.
In view of the deficiencies in the art, it would be desirable to find a reactive solvent that would solve the processing problems inherent in some reactive solvents for PAE, without deleteriously affecting the physical properties of the PAE.