Power transmission belt and cord adhesive system and adhesion method

Abstract

A power transmission belt incorporating an adhesive treatment system and method for bonding fiber to rubber which includes an optional primer coat based on a low-molecular-weight isocyanate, followed by an overcoat including: (a) a prepolymer based on an isocyanate-terminated diene oligomer, and optionally (b) a low-molecular-weight isocyanate, and/or (c) a thermoplastic urethane comprising the reaction product of the same prepolymer with MDI and EHD. A polyester, aramid, or carbon fiber tensile cord for rubber reinforcement may be treated with the primer coat and the overcoat. A power transmission belt or other dynamic rubber product having ethylene-alpha-olefin elastomer as the primary rubber constituent may be reinforced by the tensile cord.

What is claimed is: 
     
         1 . A method of bonding a textile to an elastomer composition comprising:
 a) mixing an adhesive cement comprising an isocyanate-terminated diene polymer and a solvent;   b) applying said adhesive cement to a textile to form an adhesive-cement-treated textile; and   c) drying said adhesive-cement-treated textile to form a treated textile,   wherein said isocyanate-terminated diene reacts with available moisture and/or heat such that the reaction yields predominantly polyurea and/or polyisocyanurate reaction products.   
     
     
         2 . The method of  claim 1  further comprising:
 d) bringing an elastomer composition in contact with said treated textile; and 
 e) curing said elastomer composition to effect an adhesive bond between said adhesive and said elastomer composition. 
 
     
     
         3 . The method of  claim 1  wherein said isocyanate-terminated diene polymer is the primary reactive ingredient in the adhesive cement. 
     
     
         4 . The method of  claim 1  wherein said adhesive cement further comprises a low-molecular weight isocyanate. 
     
     
         5 . The method  claim 1  further comprising:
 f) mixing a primer cement comprising a low-molecular weight isocyanate in solvent; 
 g) applying said primer cement to said textile to form a primer-cement-treated textile; and 
 h) drying and heating said primer-cement-treated textile to form a primer-treated textile, wherein said isocyanate reacts with available moisture and/or with heat to form a predominantly polyurea and/or polyisocyanurate reaction product; 
 and wherein said applying said adhesive cement is carried out on said primer-treated textile. 
 
     
     
         6 . The method of  claim 1  wherein said adhesive further comprises a low-molecular weight isocyanate and wherein said diene polymer is polybutadiene. 
     
     
         7 . The method of  claim 6  wherein the low-molecular-weight isocyanate is diphenylmethane diisocyanate or a derivative thereof, and wherein the diene polymer is isocyanate-terminated polybutadiene of molecular weight from about 2000 to about 15,000. 
     
     
         8 . The method of  claim 7  wherein said textile comprises at least one fiber selected from the group consisting of polyesters, polyamides, aramids, carbon fiber, PBO, and polyketones; and wherein said elastomer composition comprises at least one elastomer selected from the group consisting of ethylene-alpha-olefin elastomer, EPM, EPDM, SBR, BR, HNBR, cast PU, TPU, TPE, and CR. 
     
     
         9 . The method of  claim 7  wherein said textile is a tensile cord for a power transmission belt having a belt body and said belt body comprises said elastomer. 
     
     
         10 . A method of bonding a textile to an elastomer composition comprising:
 a) mixing an adhesive cement comprising an isocyanate-terminated diene polymer as the primary reactive ingredient and a solvent;   b) applying said adhesive cement to a textile to form a adhesive-cement-treated textile;   c) drying said adhesive-cement-treated textile to form a treated textile,   wherein said isocyanate-terminated diene reacts with available moisture and/or heat such that the reaction yields predominantly polyurea and/or polyisocyanurate reaction products;   d) bringing an elastomer composition in contact with said treated textile; and   e) curing said elastomer composition to effect an adhesive bond between said adhesive and said elastomer composition.   
     
     
         11 . The method of  claim 10  wherein the diene polymer is isocyanate-terminated unsaturated polybutadiene. 
     
     
         12 . The method of  claim 11  further comprising a moisture-reactive low-molecular-weight isocyanate. 
     
     
         13 . The method of  claim 12  wherein the low-molecular-weight isocyanate is diphenylmethane diisocyanate or a derivative thereof, and wherein the diene polymer is isocyanate-terminated polybutadiene of molecular weight from about 2000 to about 15,000. 
     
     
         14 . The method of  claim 12  further comprising:
 f) mixing a primer cement comprising a low-molecular weight isocyanate in solvent; 
 g) applying said primer cement to said textile to form a primer-cement-treated textile; and 
 h) drying and heating said primer-cement-treated textile to form a primer-treated textile, wherein said isocyanate reacts with available moisture and/or with heat to form a predominantly polyurea and/or polyisocyanurate reaction product; 
 and wherein said applying said adhesive is carried out on said primer-treated textile. 
 
     
     
         15 . The method of  claim 14  wherein the low-molecular-weight isocyanate is diphenylmethane diisocyanate or a derivative thereof, and wherein the diene polymer is isocyanate-terminated polybutadiene of molecular weight from about 2000 to about 15,000.