Hoses are often reinforced with continuous yarn to improve physical performance characteristics, such as burst strength. For example, radiator hoses for automobiles and trucks are generally reinforced with continuous yarn reinforcing elements. Continuous yarn reinforcements are typically used to improve the burst strength of such hoses. Even though building such fiber-reinforced hoses is a labor-intensive operation which results in a substantial amount of material waste, such techniques have been required to meet the demands of the automotive industry.
Building fiber reinforcements into hoses is a labor-intensive operation. After such hoses are built, they are typically trimmed to the exact size required. The fiber reinforcement containing material trimmed from such hoses generally has to be scrapped since it is not typically possible to recycle such fabric containing material.
Hoses have been made by extruding rubber compositions into the form of a tube which is subsequently shaped into the desired form and cured. Such techniques are advantageous in that they reduce labor costs, in-process inventory and waste. However, hoses made utilizing such extrusion techniques have typically not had the physical strength demanded by the automotive industry for radiator hose. More specifically, such hoses have had low burst strength.
By utilizing the technique disclosed in U.S. Pat. No. 5,268,134, hose which exhibits a burst strength of about 115 pounds per square inch can be made without utilizing fabric reinforcements. This process specifically comprises (1) extruding a rubber composition into the form of a tube, wherein the rubber composition is comprised of (a) an EPDM alloy comprised of (i) functionalized EPDM rubber, (ii) an EPDM rubber having thermoplastic side chains grafted thereto and (iii) dispersed thermoplastic wherein the thermoplastic is selected from the group consisting of nylons, polyesters and polyphenylene oxides, (b) an EPDM rubber, (c) carbon black, (d) at least one curative, (e) zinc oxide, (f) a processing oil and (g) stearic acid; (2) shaping the tube into the geometric form desired for the hose; and (3) curing the rubber composition at a temperature within the range of 130.degree. C. to 210.degree. C. to produce the hose.
U.S. Pat. No. 5,268,134 also discloses a process for manufacturing hose which comprises injection molding a rubber composition into the desired geometric form for the hose at a temperature which is within the range of 130.degree. C. to 210.degree. C., wherein the rubber composition is comprised of (a) an EPDM alloy comprised of (i) functionalized EPDM rubber, (ii) an EPDM rubber having thermoplastic side chains grafted thereto, and (iii) dispersed thermoplastic wherein the thermoplastic is selected from the group consisting of nylons, polyesters, and polyphenylene oxides, (b) an EPDM rubber, (c) carbon black, (d) at least one curative, (e) zinc oxide, (f) a processing oil, and (g) stearic acid; (2) shaping the tube into the geometric form desired for the hose; and (3) curing the rubber composition at a temperature within the range of 130.degree. C. to 210.degree. C. to produce the hose.