MINERAL FIBER REINFORCED POLYCARBONATE

Abstract: Novel thermoplastic molding compositions which comprise (a) a bisphenol-A polycarbonate; in admixture with (b) a quantity of a processed mineral fiber reinforcing agent.

Description: Description Mineral Fiber Reinforced Polycarbonate This invention relates to thermoplastic molding compositions having improved physical characteristics comprising (a) a bisphenol-A polycarbonate; in admixture with (b) a quantity of a processed mineral fiber reinforcing agent. Background of the Invention The use of bisphenol-A polycarbonates are molding compositions, both with and without reinforcing agents, is well known and these materials have been widely employed in the manufacture of various thermoplastic molded articles. In the preparation of such bisphenol-A poly¬ carbonates for use as molding compositions, one may employ glass fibers or a mixture of glass fibers and glass beads in various amounts which improve the tensile, flexural and heat distortion properties of the molded article in proportion to the amount of such material employed. It has now been found that the incorporation of a quantity of a low cost, processed mineral fiber reinforcing agent in a bisphenol-A polycarbonate will also significantly improve the overall physical characteristics of the resultant polycarbonate molding composition, at a much lower cost than could be obtained without the use of such a material. Description of the Invention The present invention provides for a novel thermoplastic molding composition which comprises (a) a bisphenol-A polycarbonate; in admixture with (b) a quantity of a processed mineral fiber reinforcing agent. The polycarbonate resin has recurring units of the formula X I - R - C - R - O - C - 0 - Y O wherein each -R- is selected from the group consist- ing of phenylene, halo-substituted phenylene and alkyl substituted phenylene, and X and Y are each selected from the group consisting of hydrogen, hydrocarbon radicals free from aliphatic unsatura- tion and of radicals which together with the adjoining atom form a cycloalkane radical, the total number of carbon atoms in X and Y being up to 12. The preferred polycarbonate resins may be derived from the reaction of bisphenol-A poly¬ carbonate and phosgene. These polycarbonates have from 10-400 recurring units of the formula: The polycarbonates are described in U.S. Patents Nos. 3,028,365; 3,334,154 and 3,915,926 all of which are incorporated by reference. The polycarbonate should have an intrinsic viscosity between 0.2 and 1.0, preferably from 0.30 to 0.65 as measured at 20°C in methylene chloride. Although it is only necessary to use a rein¬ forcing amount of the mineral fiber reinforcing agent in the compositions of the present invention, from 1-60 parts by weight of the total weight of the resultant molding composition may comprise the reinforcing agent. A preferred range is from 5-40 parts by weight. The preferred mineral fiber reinforcing agents for use in the present invention are typically derived from mineral wool and have average fiber diameters in the order of from about 4-5 microns, and typically will have an aspect ratio (length/ diameter) of from about 40-60. The preferred fibers for use in the present invention are single m- Δ - strands unlike the fiber bundles conventionally used as glass fiber reinforcement agents. The preferred mineral fiber reinforcing agents for use in the present invention are commercially available products manufactured and sold by Jim Walter Research Corporation, 10301 Ninth Street North, St. Petersburgh, Florida. Description of the Preferred Embodiments The following examples are set forth to further illustrate the present invention and are not to be construed as limiting the invention thereto. EXAMPLE I - CONTROL / ~~ \ A blend of 100 parts by weight of LEXAN 140 grade of bisphenol-A polycarbonate and 0.1 parts by weight of epoxy stabilized octadecyl phenol*phosphite was prepared, extruded in a twin screw extruder and molded into sample parts of approximately 1/8 inch thickness. The results of various physical tests performed on this material is given in Table I. EXAMPLES II - V Various blends of LEXA ^140 grade of bisphenol-A polycarbonate, a processed mineral fiber reinforcing agent and epoxy stabilized octadecyl phenyl phosphite* were prepared in the proportions indicated in Table I, and extruded and * Epoxy stabilized octadecyl phenyl phosphite is a thermal stabilizer commonly used with poly¬ carbonates. The use of this particular agent or its equivalent is not essential to obtain the. benefits of the instant invention. O. PI molded into sample parts in the same manner as in Example I. The results of various physical tests performed on these materials is set forth in Table I. TABLE I - EXAMPLES I - V COMPOSITION EXAMPLE I EXAMPLE II EXAMPLE III EXAMPLE IV EXAMPLE V (parts by weight) Poly(BPA carbonate) 100 90 80 70 60 (LEXAN R 140) Processed Mineral Fiber 10 20 30 40 Epoxy Stabilized Octadecyl 0.1 0.1 0.1 0.1 0.1 Phenyl Phosphite (phr) PROPERTIES I <Tι DTUL °C(°F at 18.6 kg/cm (264 psi) 127 (260) 133 (272) 134 (274) 136 (277) 138 (280) Flex. Modulus- (xl0 ~3 ) kg/cnT (psi) 24.1 (343) 29,4 (418) 36.9 (525) 47.7 (678) 57.8 (822) Flex. Yield (xlO -3 ) kg/cπT (psi) 0.94 (13.5) 1.01 (14.4) 1.08 (15.4) 1.07 (15.2) 1.17 (16.6) Although the above examples show various modifications of the present invention, other variations are possible in light of the above teachings. Obviously, other materials can also be employed with the aromatic carbonate polymer of this invention and include such materials as: antistatic agents, pigments, thermal stabilizers, ultraviolet stabili¬ zers, impact modifiers and the like. It is, therefore, to be understood that changes may be made in the particular embodiment of the invention described which are within the full intended scope of the invention, as defined by the appended claims.

Claims: Claims 1. A thermoplastic molding composition which comprises (a) a bisphenol-A polycarbonate; in admixture with (b) a quantity of a processed mineral fiber reinforcing agent. 2. A thermoplastic molding composition as defined in claim 1 wherein the polycarbonate consists essentially of recurring units of the formula: X wherein each -R- is selected from the group consist¬ ing of phenylene, halo-substituted phenylene and alkyl substituted phenylene and X and Y are each selected from the group consisting of hydrogen, hydrocarbon radicals free from aliphatic unsatura- tion and of radicals which together with the adjoining atom form a cycloalkane radical, the total number of carbon atoms in X and Y being up to 12. 3. A thermoplastic molding composition as defined in claim 2 wherein the polycarbonate has the repeating unit 0 4. A thermoplastic molding composition as defined in claim 3 wherein the polycarbonate resin consists of from 10 to 400.repeating units. 5. A thermoplastic molding composition according to claim 1 wherein the processed mineral 5 fiber reinforcing agent is present in an amount about 1 to about 60 percent by weight. 6. A thermoplastic molding composition according to claim 1 wherein the processed mineral fiber reinforcing agent is present in an amount from 20. about 5 to about 40 percent by weight. 7. A thermoplastic molding composition as defined in claim 1 which includes a flame retardant amount of a flame retardant agent. 8. A method of preparing a bisphenol-A poly- 25 carbonate molding composition having improved physical characteristics which comprises adding to the polycarbonate molding powder a quantity of a processed mineral fiber reinforcing agent. 9. A method of preparing a bisphenol-A poly¬ carbonate molding composition having improved physical characteristics which comprises adding to the polycarbonate molding powder from about 1 to about 60 percent by weight of a processed mineral fiber reinforcing agent. 10. A method of preparing a bisphenpl-A poly¬ carbonate molding composition having improved physical characteristics which comprises adding to the polycarbonate molding powder from about 5 to about 40 percent by weight-of a processed mineral fiber reinforcing agent. 11. A method as defined in claim 8 wherein the polycarbonate has recurring units of the formula: X - R C 1 - R 0 - C - 0 Y O wherein each -R- is selected from the group consist¬ ing of phenylene, halo-substituted phenylene and alkyl substituted phenylene, and X and Y are each selected from the group consisting of hydrogen, hydrocarbon radicals free from aliphatic unsatura- tion and of radicals which together with the adjoining atom form a cycloalkane radical, the total number of carbon atoms in X and Y being up to 12. 12. A method as defined in claim 11 wherein the polycarbonate has the repeating unit 13. A method as defined in claim 12 wherein the polycarbonate resin consists of from 10 to 400 repeating units.

Inventors: WILSON P
Applicants: GEN ELECTRIC, GENERAL ELECTRIC CO
Application year: 1979
Main classification: C08L69
IPC codes: C08K7