REINFORCED INJECTION MOLDABLE BLENDS

Abstract: An injection moldable composition containing an aromatic polymer including a heterocyclic group, a low viscosity melt processible at least partially aromatic polymer selected from the group consisting of polyethers, polyketones, polyetherketones, polyether-ether ketones, polyamides, and polyesters, and a reinforcing agent. The reinforcing agent is glass fiber, carbon fiber, or a combination thereof.

Description: REINFORCED INJECTION MOLDAB E BLENDS Background Of The Invention This invention relates to the field of polymer blends, especially fiber-reinforced injection moldable blends. A variety of polymer blends are known in the art, including injection moldable blends. Polymer blends are made to take advantage of a synergy between the blended polymers, or to combine different properties not found in a single polymer. Polymers are sometimes mixed with fibers, e.g., glass fibers, graphite fibers, etc., to physically reinforce the polymer and enhance the physical properties of the neat polymer. Fiber reinforcement can be a simple and inexpensive way to obtain a polymer composition having certain desired properties. U.S. Patent Number 5,070,153 discloses an injection molded article formed from a homogeneous mixture comprising polybenzimidazole and polyaryleneketone. U.S. Patent Number 4,912,176 discloses a sintered molded article formed from a homogeneous mixture comprising polybenzimidazole and polyaryleneketone. Fillers may be included in these, including glass and carbon fiber. U.S. Patent Number 4,965,310 discloses wear resistant blends comprising at least one polyaryletherketone and at least one polyimide. U.S. Patents Number 4,980,447 and 5,071,948 disclose polyamide-polyimide and polybenzazole-polyimide polymers that may be molded, and may be compounded with fibers to form high strength structures. U.S. Patent Number 4,340,697 discloses a heat resistant molding resin comprising an aromatic polyamideimide resin and a thermoplastic resin. The composition may be filled with fibers or other fillers. Other patents relating to polymer blends include U.S. Patents Number: 4,973,629; 4,973,630; and 5,047,487. The disclosures of the patents cited above are incorporated by reference herein. Summary Of The Invention The present invention is an injection moldable composition comprising: a first polymer selected from the group consisting of polymers represented by and where A and A 1 each independently represent B represents 0 or NH, R 1 represents CH 2 , R 2 represents H or CH 3 , R represents either a covalent bond or CR 3 R 4 , R 3 and R 4 each independently represent H or CXYZ, and X, Y, and Z are each independently H, F, or Cl; a melt processible polymer including aromatic recurring moieties, having a viscosity of no more than about 300 centipoise, said melt processible polymer selected from the group consisting of polyethers, polyketones, polyetherketones, polyether-ether ketones, polyamides, and polyesters; and, a reinforcing agent selected from the group consisting of glass fiber and carbon fiber. Detailed Description Of The Preferred Embodiments In one preferred embodiment according to the present invention, poly[2,2' (m-phenylene)-5,5 ' -bibenzimidazole] ("PBI") resin is mixed thoroughly with polyetheretherketone ("PEEK") resin having a viscosity of less than about 300 centipoise and graphite fiber, each of the three ingredients being present in approximately the same amounts by weight. PEEK is an aromatic polymer having a repeating unit of formula The composition is injected into a mold and cold compressed at 20,000 psi for about 2 minutes. The molded article is then placed in a 785°F oven. After three hours in the oven, the article is again pressed at 20,000 psi for one minute at 785°F. The article remains another three and one-half hours in the oven and is then given a final hot press for three and one-half minutes at 785°F and 20,000 psi. This procedure is suitable for relatively small objects, e.g, a bar about 4-6 inches long and 1-2 inches thick. For larger objects it may be desirable to increase oven and/or compressing times. The pressure and temperature may also vary, depending on the size and shape of the object, the exact polymer composition used, and the use for which the article is intended. Those skilled in the art will be able to determine suitable times, temperatures, and pressures. The reinforcing fiber may be glass or carbon, or a mixture of the two may be used. The length of the fibers included in the composition of this invention preferably is in the approximate range of 1/64 to 1/2 inch, e.g., about 1/32 inch. The proportion of the ingredients in this composition may vary. For example, the proportion by weight of PBI/PEEK/fiber may be in the approximate range of 10-50/20-60/10-40, preferably 20-40/30-50/25-35. Examples of suitable weight proportions include 35/35/30, 30/40/30, 30/35/35, and the like. Other polymers may be substituted for the above- named PBI; these polymers include other polybenzimidazoles, polyimides, polyamideimides, and polybenzoxazoles. Generally, these polymers have repeating units selected from one of the following formulas: or where A and A' each independently represent B represents 0 or NH, R 1 represents CH 2 , R 2 represents H or CH 3 , R represents either a covalent bond or CR 3 R 4 , R 3 and R 4 each independently represent H or CXYZ, and X, Y, and Z are each independently H, F, or Cl. The second polymer is a melt processible, at least partially aromatic, polymer selected from polyethers, polyketones, polyetherketones, polyether-ether ketones, polyamides, and polyesters. The viscosity of this polymer is crucial; if the viscosity exceeds about 300 cp the resulting composition cannot be injection molded. The composition of the present invention may optionally include minor amounts of other ingredients, such as sizing or coupling agents, added fillers, pigments, and the like. Preferably, such additional ingredients do not comprise more than about 5% of the total weight of the composition. The compositions of the present invention have a unique combination of attributes and advantages, including being easily moldable or processible, forming strong, durable articles, and having good chemical, physical and high temperature resistance. The precise properties depend, of course, on the exact composition. These compositions are generally useful for a variety of molded parts, especially injection molded parts, e.g., sealing rings, and the like. These compositions may also be used where sintered parts are desired, using the procedure set forth in U.S. Pat. No. 4,912,176, or other methods known in the art. The following non-limiting Examples illustrate several embodiments of the present invention. However, these Examples are only intended as illustrative, and the scope of the present invention is not limited to the embodiments illustrated herein; the scope of the present invention encompasses the entire subject matter covered by the appended claims. EXAMPLE I A blend of 100 mesh PBI (32.5% by weight), PEEK having a viscosity of 150 centipoise (35% by wt) , glass fiber (30% by wt) and a sizing agent (2.5% by wt; containing 10% active ingredient neoalkenolato tris (3- amino) phenylato zirconium (VI) and obtained from Petro Chemicals under the designation NZ09) was prepared by combining these ingredients in a high speed blender. The blend was injected into a mold and cold compressed at 20,000 psi for 2 minutes and then placed in an oven maintained at 785°C where it remained for three hours. The molded article was then compressed for one minute at 785°C and 20,000 psi, left an additional 3.5 hours in the oven, and given a final hot press at 785°C and 20,000 psi for 3.5 minutes. EXAMPLE II A blend of 100 mesh PBI (27% by weight) , PEEK having a viscosity of 150 centipoise (40.5% by wt) , graphite fiber (30% by wt) and the sizing agent of Ex. I (2.5% by wt) was prepared and injection molded using the procedure of Example I. A molded article resulted. Many variations and equivalents of the present invention will occur to those skilled in the art. The present invention is not limited to the embodiments illustrated or described, but includes all the subject matter within the spirit and scope of the appended claims and of the foregoing disclosure.

Claims: Claims 1. An injection moldable composition comprising: a first polymer selected from the group consisting of polymers of the formula and αe..ιtly represent B represents 0 or NH, R 1 represents CH 2 , R 2 represents H or CH 3 , R represents either a covalent bond or CR 3 R 4 , R 3 and R 4 each independently represent H or CXYZ, and X, Y, and Z are each independently H, F, or Cl; a melt processible polymer including aromatic recurring moieties, having a viscosity of no more than about 300 centipoise, said melt processible polymer selected from the group consisting of polyethers, polyketones, polyetherketones, polyether-ether ketones, polyamides, and polyesters; and. a reinforcing agent selected from the group consisting of glass fiber and carbon fiber. AMENDED CLAIMS [received by the International Bureau on 27 August 1993 (27.08.93); original claim 1 cancelled; new claims 2-6 added (2 Pages) ] 2. An injection moldable composition comprising: approximately 20-40 weight % of poly[2,2 ' - (m- phenylene)-5,5'-bibenzimidazole] ; 5 approxia tely 30-50 weight % of polyetheretherketone having a viscosity of no more than about 300 centipoise; and, approximately 25-35 weight % of a reinforcing agent selected from the group consisting of glass fiber 10 and carbon fiber. 3. An injection moldable composition according to Claim 2 further comprising no more than about 5 weight percent of a sizing agent which comprises a neoalkenolato tris (3-amino) phenylato zirconium(VI) 15 compound. 4. An injection moldable composition according to Claim 3 wherein said compound comprises about 10% by weight of said sizing agent. 5. An injection moldable composition arrn f!'- B „ 20 Claim 4 'herein said sizing ~ ~ X '"'" 6. An injection moldable composition consisting essentially of: approximately 20-40 weight % of poly[2,2 '- (m- phenylene) -5,5' -benzi idazole] ; approximately 30-50 weight % of polyetheretherketone having viscosity of no more than about 300 centipoise; approximately 25-35 weight % of a reinforcing agent selected from the group consisting of glass fiber and carbon fiber; and, no more that about 5 weight percent of a sizing agent which comprises a neoalkenolato tris (3-amino) phenylato zirconiu (VI) compound.

Inventors: ALVAREZ EDUARDO, WANG CHUN, ALVAREZ, EDUARDO, WANG, CHUN
Applicants: HOECHST CELANESE CORP, HOECHST CELANESE CORPORATION
Application year: 1993
Main classification: C08L77
IPC codes: C08K5, C08K7, C08L67, C08L71, C08L73, C08L77, C08L79