Carbon black containing EPDM compositions having a textured matte finish

Abstract: EPDM compositions comprising EPDM and specified carbon blacks which, when extruded or shaped, exhibit a textured matte finish. The carbon black is present in an amount of 100 to 300, and more preferably 150 to 250 parts by weight per 100 parts by weight EPDM.

Description: FIELD OF THE INVENTION The present invention relates to EPDM compositions containing certain carbon blacks which when extruded or shaped have a textured matte finish. BACKGROUND Carbon blacks have been widely utilized as fillers and reinforcing pigments in the compounding and preparation of EPDM compositions. Carbon blacks are generally characterized on the basis of their properties including, but not limited to, their surface areas, surface chemistry, aggregate sizes, and particle sizes. The properties of carbon blacks are analytically determined by tests known to the art, including iodine adsorption number (I 2 No.) and dibutyl phthalate adsorption (DBP). Heretofore generally known carbon black containing EPDM compositions yield profiles having a dull and flat surface finish when extruded or shaped. In contrast, a smooth glossy finish has a high degree of reflectance when viewed at any angle, in part due to the smooth nature of the surface. Conversely, a textured matte finish has a low degree of reflectance due in part to the rugged nature of the surface. EPDM compositions with high gloss or textured matte finishes are useful in industrial applications such as automotive weather stripping. SUMMARY OF THE INVENTION We have discovered EPDM compositions containing certain carbon blacks that yield profiles having textured matte finishes when extruded or shaped. The EPDM compositions comprise ethylene-propylene diene monomer (EPDM) and a specified carbon black, which when incorporated into the EPDM will provide articles having a desired textured matte finish. The amount of carbon black in the EPDM composition is such that the EPDM composition will, when extruded or shaped, yield profiles having a textured matte finish. The amounts of carbon black utilized range from 100 to about 300 parts by weight for each 100 parts by weight of EPDM. It is, however, preferred to use amounts varying from about 150 to about 250 parts by weight of carbon black per 100 parts by weight of EPDM. EPDM is well known and is commercially available from a variety of sources. The EPDM composition of the present invention may be produced by techniques generally known to those of ordinary skill in the art for mixing rubbers or polymers and carbon black. As will be understood by those of ordinary skill in the art the high gloss and textured matte finish EPDM compositions of the present invention are produced after extruding or otherwise shaping the carbon black-EPDM mixture. The textured matte finish EPDM compositions of the present invention are advantageous for use in applications where a textured matte finish is desirable. One such application is automotive weatherstripping. Other advantages of the present invention will become apparent from the following more detailed description of the invention. DETAILED DESCRIPTION OF THE INVENTION The EPDM compositions of the present invention which will yield a high gloss finish comprise EPDM and a carbon black selected from the group consisting of carbon blacks having a CTAB of about 10 m 2 /g to about 30 m 2 /g and a ratio of DBP/CTAB greater than about 4, preferably a CTAB of about 25 m 2 /g and a ratio of DBP/CTAB of about 5.3; and carbon blacks having a CTAB of about 30 m 2 /g to about 70 m 2 /g and a DBP greater than about 125 cc/100g, preferably a DBP of about 125 cc/100g to about 160 cc/100g, and most preferably a CTAB of about 47 m 2 /g and a DBP of about 126 cc/100g. The EPDM compositions of the present invention which will yield a textured matte finish comprise EPDM and a carbon black having a CTAB of about 10 m 2 /g to about 70 m 2 /g and a ratio of DBP/CTAB less than about 1.5, preferably a CTAB of about 45 m 2 /g and a ratio of DBP/CTAB of about 1.0, and most preferably a CTAB of about 67 m 2 /g and a ratio of DBP/CTAB of about 0.7. The amount of carbon black in the compositions of the present invention is sufficient to allow the EPDM composition to yield a profile having either a gloss or a textured matte finish after extruding or shaping. The amounts of carbon black to be incorporated into the EPDM compositions of the present invention range from 100 to about 300 parts by weight carbon black per 100 parts by weight EPDM, preferably from about 150 to about 250 parts by weight carbon black per 100 parts by weight EPDM. The textured matte finish EPDM compositions of the present invention may also contain conventional additives such as oils, stabilizers, oxides, acids, curing agents etc. known to those of ordinary skill in the art as useful for incorporation into, and during the formation of, EPDM compositions. The textured matte finish EPDM compositions of the present invention may be produced in any manner known to those of ordinary skill in the art for producing EPDM compositions incorporating carbon blacks. One method for producing the high gloss or textured matte finish compositions of the present invention, utilizing a Banbury BR mixer, is as follows. The Banbury BR mixer is started and maintained at a temperature of 45° C and a rotor speed of 77 RPM. EPDM is added to the mixer and mixed for approximately 30 seconds. oil, and preferably zinc oxide and stearic acid, or compounds having similar properties, are added to the EPDM and mixed for approximately 2 additional minutes. The carbon black is added to the mixture and the temperature of the mixing chamber is cooled and maintained at a temperature of below approximately 135° C. The carbon black - EPDM mixture is mixed for approximately 4 1/2 minutes and then curing agents are added to the mixture. The resulting mixture is mixed for approximately 1 1/2 minutes while the temperature is maintained at below approximately 135° C. The compound is then discharged from the mixer and extruded, or otherwise formed and cooled to form the high gloss or textured matte finish EPDM compositions of the present invention. By way of example, the batch compound may be extruded on a Brabender extruder at 50 RPM and 100° C through a die having an opening of 1 inch in width and 0.020 inch in height. This will yield a profile having a high gloss or textured matte finish. Although one method for producing the textured matte finish EPDM compositions of the present invention has been described, the textured matte finish EPDM compositions of the present invention may be produced'by other methods for producing polymer or rubber compositions known to those of ordinary skill in the art. The following testing procedures are used in the determination and evaluation of the analytical properties of the carbon blacks utilized in the following examples. The DBP (dibutyl phthalate adsorption value) of the carbon black was determined according to the procedure set forth in ASTM D2414. The I 2 No. (iodine adsorption number) of the carbon blacks was determined according to ASTM D1510. CTAB (cetyl-trimethyl ammonium bromide) absorption value of the carbon blacks was determined according to ASTM Test Procedure D3765-85. Tinting strength (Tint) of the carbon blacks was determined according to ASTM Test Procedure D3265-85a. The CDBP (dibutyl phthalate adsorption value) of the crushed carbon blacks was determined according to the procedure set forth in ASTM D3493-86. The effectiveness and advantages of the present invention will be further illustrated by the following example. EXAMPLE Eighteen EPDM compositions were prepared incorporating six different carbon blacks at each of three different loading levels into EPDM. Carbon blacks A and B were utilized to produce textured matte finish EPDM compositions of the present invention RA1 - RA3 and RB1 - RB3, respectively. Two control carbon blacks, C and D, were utilized to produce EPDM compositions RC1 - RC3 and RD1 - RD3, respectively. Carbon blacks E and F were utilized to produce high gloss EPDM compositions of the present invention RE1-RE3 and RF1-RF3, respectively. The analytical properties of the carbon blacks A-F were as shown in Table 1 below: Carbon Blacks A B C D E F I 2 No. (mg/g) 40 63 30 35 22 51 CTAB (m 2 /g) 45 67 30 36 25 47 DBP (cc/100g) 44 49 69 91 132 126 CDBP cc/100g 43 45 59 72 77 83 Tint (%) 80 101 52 57 33 60 DBP/CTAB 1.0 0.7 2.3 2.5 5.3 2.7 EPDM compositions RA1, RA2, RA3; RB1, RB2, RB3; RC1, RC2, RC3; RD1, RD2, RD3; RE1, RE2, RE3; and RF1, RF2, RF3 were prepared utilizing each of the carbon black samples in amounts of 150 parts by weight, 200 parts by weight and 250 parts by weight parts by weight, 200 parts by weight and 250 parts by weight in the EPDM Compound Formulation shown below in Table 3. The carbon black and amount by weight of the carbon black utilized in the EPDM compositions were as shown in Table 2. EPDM COMPOSITION CARBON BLACK AMOUNT BY WEIGHT RA1 A 150 RA2 A 200 RA3 A 250 RB1 B 150 RB2 B 200 RB3 B 250 RC1 C 150 RC2 C 200 RC3 C 250 RD1 D 150 RD2 D 200 RD3 D 250 RE1 E 150 RE2 E 200 RE3 E 250 RF1 F 150 RF2 F 200 RF3 F 250 EPDM COMPOUND FORMULATION INGREDIENT PART BY WEIGHT EPDM 100 Carbon Black 150/200/250 Sunpar 2280 Oil 100 Zinc Oxide 5 Stearic Acid 1 TMTDS 2.7 Butyl Zimate 2.7 Methyl Zimate 2.7 Sulfur 0.5 Sulfasan R 1.7 EPDM -EXXON VISTALON® 5600, manufactured and sold by EXXON Corporation, Wilmington, Delaware; Sunpar 2280 - A trademarked oil manufactured and sold by Sun Oil Company; TMTDS - tetramethylthiuram disulfide; Butyl Zimate - a trademarked zinc dibutyldithiocarbamate manufactured and sold by R. T. Vanderbilt Co.; Methyl Zimate - a trademarked zinc dimethyldithiocarbamate manufactured and sold by R. T. Vanderbilt Co.; Sulfasan R - a trademarked 4,4' - dithiodimorpholine, manufactured and sold by Monsanto, Co., St. Louis, Missouri. The EPDM compounds were produced as follows. A Banbury BR mixer was started and maintained at a temperature of 45° C and a rotor speed of 77 RPM. EPDM was added to the mixer and mixed for approximately 30 seconds. The Sunpar 2280 oil, zinc oxide and stearic acid, were added to the EPDM and mixed for approximately 2 additional minutes. The carbon black was added to the mixture and the temperature of the mixing chamber was cooled and maintained at a temperature of below approximately 135° C. The carbon black - EPDM mixture was mixed for approximately 4 1/2 minutes and then the TMTDS, Butyl Zimate, Methyl Zimate, Sulfur and Sulfasan R products were added to the mixture. The resulting mixture was mixed for approximately 1 1/2 minutes while the temperature was maintained at below approximately 135° C. The batch compound was then discharged from the mixer and extruded on a Brabender extruder at 50 RPM and 100°C. through a die having an opening of 1 inch in width and 0.020 inch in height to produce the EPDM compositions RA1-RF3 in the form of profiles. Upon visual inspection, the finish of each of the EPDM profiles was as follows: EPDM COMPOSITION FINISH RA1 Textured Matte RA2 Textured Matte RA3 Textured Matte RB1 Textured Matte RB2 Textured Matte RB3 Textured Matte RC1 Dull and Flat RC2 Dull and Flat RC3 Dull and Flat RD1 Dull and Flat RD2 Dull and Flat RD3 Dull and Flat RE1 High Gloss RE2 High Gloss RE3 High Gloss RF1 High Gloss RF2 High Gloss RF3 High Gloss These results show that the EPDM compositions RA1-RA3 and RB1-RB3 of the present invention have a textured matte finish whereas EPDM compositions RE1-RE3 and RF1-RF3 have a high gloss finish. Samples produced with the control carbon blacks, RC1-RC3 and RF1-RF3, have a dull and flat surface appearance which is neither highly glossy nor textured matte.

Claims: Process for preparing an EPDM composition having a textured matte finish in a manner known per se, characterized in that an EPDM and a carbon black having a CTAB of 10 m 2 /g to 70 m 2 /g and a ratio of DBP/CTAB less than 1.5 are used, wherein the carbon black is present in an amount of 100 to 300 parts by weight carbon black per 100 parts by weight EPDM. Process for preparing an EPDM composition according to claim 1 wherein the carbon black is present in an amount of 150 to 250 parts by weight carbon black per 100 parts by weight EPDM. Process according to anyone of the preceding claims, characterized in that the composition is shaped to become an automotive wheather stripping.

Inventors: CHUNG BIN, FUNT JOHN M, MACKAY BRUCE E, WILKINSON MARK A, CHUNG, BIN, FUNT, JOHN M., MACKAY, BRUCE E., WILKINSON, MARK A.
Applicants: CABOT CORP, CABOT CORPORATION
Application year: 1993
Main classification: C08K3
IPC codes: C08K3