Acrylate-grafted elastomers as polymer modifiers

#It is well known that diverse synthetic resinous materials are, by and large and inherently, mutually incompatible. Essentially because of this, physical admixtures of most given different polymers--such as those gotten from melt blending procedures--are usually opaque blended polymer (i.e., "polyblend") products. The theory and practice of polymer compatibility and blending is nicely documented as a recent presentation set forth in Polymer Blends, Vols. 1 and 2, by D. R. Paul and Seymour Newman, Academic Press (a Subsidiary of Harcourt Brace Jovanovich) Publishers of New York, San Francisco and London (1978).

#There are, nonetheless, a fair number of known and established exceptions to the foregoing generality. U.S. Pat. Nos. 3,177,268; 4,083,896; and 4,113,798 and French Pat. No. 1,526,375 are indicative of this. Likewise, the copending, concurrently filed application of the present Applicants pertains, inter alia to impact modification of mass-made ABS (acrylonitrile-butadiene-styrene) and ABS-type resins by means of polyblending thereof with particular grafted acrylate polymers; the same having Ser. No. 255,956; filed Apr. 20, 1981 and entitled "Blends of Grafted Acrylate Polymers and Mass-Made ABS-type Resins".

#Notwithstanding, the general incompatibility of polystyrene (i.e., "PS") and most other St (styrene) and the like polymers with PMMA (polymethylmethacrylate) is notoriously well known. The result of attempted mixing of such diverse polymer products is an invariably heterogeneous composition of less than desired properties. Thus, even the mixture of typical styrene/acrylonitrile (i.e., "SAN") copolymers with conventional rubber-modified, high impact polystyrene (i.e., "HIPS") causes reduction of impact strength-values of the involved HIPS. Analogously, due to the recognized incompatibility of the included PS and SAN in the involved matrixes, a markedly brittle blend (usually having less than about a 0.5 ft-lbs/in value in measured Izod Notched Impact strength taken at 73.degree. F. which is 22.8.degree. C.) is had when typical and conventional ABS and HIPS resins are admixed.

#The following illustrative examples show the great benefit of reduction to practice of the present invention. In them, all parts and percentages are given and to be taken on a weight basis and all temperature readings (unless otherwise specified) are in degrees Centigrade (.degree.C).

#In each illustration, the polyblends involved were prepared from granular stock. The Components to be blended were first physically mixed in measured quantities. This was followed by melting of the physical mixture on a 3.times.8 inch (ca. 7.62.times.20.32 centimeter) 2-roll mill. The front roll of the mill was kept supplied with steam at 200-240 psig so that its surface temperature was maintained at 160.degree.-190.degree.. The back roll of the mill was unheated. Each composite was milled for 5-7 minutes with frequent folding of the polyblend blanket being made. After the blending, each polyblend so made was compression molded into 1/8 inch (ca. 0.3175 centimeter) thick sheet from which suitably sized specimens were cut. Mechanical properties testing of the specimens was conducted by appropriated ASTM procedures. The Notched Izod (i.e., "N.I.") values, unless other noted, were determined at 22.8.degree., with results reported in ft-lbs/in. The Melt Flow Rate (i.e., "MFR") values were determined according to the American Society for Testing Materials Standard D-1238 condition "I", with results reported in grams (of flow)/10 minutes. Vicat heat distortion values, when made, were determined and reported in .degree.C.

#A series of polyblends were made using: as Component (Al), GRC(MMA)'s containing 78.1% and 77.3%, respectively, of PBD as the included El and having an unattached PMMA contents of about 7.1% and 9.7%, respectively (having been prepared excepting for appropriate ingredient variations generally in accordance with the method set forth in the First Illustration of the above referred to copending and concurrently-filed application of the Applicants); and, as Component (B1), various proportional combinations (including in some cases none of one or the other) of: "STYRON 666", a general purpose PS from The Dow Chemical Company, which is identified in the following tabulation as "B1.sub.a "; and "STYRON 492", a rubber-modified HIPS containing 6.5% interpolymerized PBD from The Dow Chemical Company which is identified in the following tabulation as "B1.sub.b ".