Microgel-containing vulcanizable composition based on hydrogenated nitrile rubber

Abstract

A novel vulcanizable composition is provided, based on at least one hydrogenated nitrile rubber, on at least one peroxide, on at least one unsaturated carboxylic acid and/or salts thereof, and also on specific microgels. These vulcanizable compositions can be used to obtain vulcanized products which can in particular be used for drive belts, roll coverings, hoses and cables.

1 . A vulcanizable composition comprising 
 a) one or more hydrogenated nitrile rubbers,    b) one or more unsaturated carboxylic acids and/or one or more salts thereof,    c) at least one peroxide and    d) at least one microgel whose glass transition temperature is below −20° C.    
   
   
       2 . The vulcanizable composition according to  claim 1 , wherein the component a) used comprises one or more hydrogenated nitrile rubbers which are co- or terpolymers based on at least one conjugated diene and on at least one α,β-unsaturated nitrile monomer and also if appropriate on other copolymerizable monomers, in which the diene units incorporated into the polymer have been entirely or to some extent hydrogenated.  
   
   
       3 . The vulcanizable composition according to  claim 1  or  2 , wherein the component a) used comprises one or more hydrogenated nitrile rubbers in which the Mooney viscosity (ML 1+4 @ 100° C.) is in the range from 10 to 120 MU, where the Mooney viscosity is determined to ASTM standard D1646.  
   
   
       4 . The vulcanizable composition according to  claim 1  or  2 , wherein the component a) used comprises one or more hydrogenated nitrile rubbers in which the Mooney viscosity (ML 1+4 @ 100° C.) is in the range from 15 to 100 MU, where the Mooney viscosity is determined to ASTM standard D1646.  
   
   
       5 . The vulcanizable composition according to  claim 1  or  2 , wherein the component b) used comprises one or more unsaturated carboxylic acids and/or one or more salts thereof and the unsaturated carboxylic acid can be an α,β-ethylenically unsaturated mono- or dicarboxylic acid having from 3 to 10 carbon atoms.  
   
   
       6 . The vulcanizable composition according to  claim 1  or  2 , wherein the component b) used comprises one or more unsaturated carboxylic acids and/or one or more salts thereof and the unsaturated carboxylic acid is selected from the group consisting of methacrylic acid, acrylic acid, cinnamic acid, crotonic acid and itaconic acid and the salts are selected from the group consisting of sodium, potassium, magnesium, calcium, zinc, barium, aluminium, tin, zirconium and lithium.  
   
   
       7 . The vulcanizable composition according to  claim 1  or  2 , wherein the component b) used comprises one or more metal diacrylates and/or metal dimethacrylates.  
   
   
       8 . The vulcanizable composition according to  claim 1  or  2 , wherein the component b) used comprises zinc diacrylate or zinc dimethacrylate.  
   
   
       9 . The vulcanizable composition according to  claim 1  or  2 , wherein the component c) used comprises at least one peroxide.  
   
   
       10 . The vulcanizable composition according to  claim 1  or  2 , wherein the component c) used comprises at least one peroxide selected from the group consisting of dicumyl peroxide, tert-butyl cumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, di-tert-butyl peroxide, 2,5-dimethylhexane 2,5-dihydroperoxide, 2,5-dimethylhex-3-yne 2,5-dihydroperoxide, dibenzoyl peroxide, bis(2,4-dichlorobenzoyl)peroxide, tert-butyl perbenzoate, butyl 4,4-di(tert-butylperoxy)valerate and 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.  
   
   
       11 . The vulcanizable composition according to  claim 1  or  2 , wherein the component d) used comprises at least one microgel whose glass transition temperature is below −20° C. and which is a crosslinked homopolymer or crosslinked random copolymer.  
   
   
       12 . The vulcanizable composition according to  claim 1  or  2 , wherein the component d) used comprises at least one microgel whose glass transition temperature is below −20° C. and which has at least 70% by weight of fractions (“gel content”) insoluble in toluene at 23° C.  
   
   
       13 . The vulcanizable composition according to  claim 1  or  2 , wherein the component d) used comprises at least one microgel whose glass transition temperature is below −20° C. and which has a swelling index (“SI”) in toluene at 23° C. of less than 80, where the swelling index is calculated from the weight of the solvent-containing microgel swollen for 24 hours in toluene at 23° C. (after centrifuging at 20 000 rpm) and the weight of the dry microgel by using the following formula:  
         SI =wet weight of microgel/dry weight of microgel.  
   
   
       14 . The vulcanizable composition according to  claim 1  or  2 , wherein the component d) used comprises at least one microgel whose glass transition temperature is in the range from −100° C. to −20° C.  
   
   
       15 . The vulcanizable composition according to  claim 1  or  2 , wherein the component d) used comprises at least one microgel whose glass transition temperature is below −20° C. and which has been selected from the group consisting of BR (polybutadiene), IR (polyisoprene), SBR (random styrene-butadiene copolymers with styrene contents of 1-60% by weight, preferably 5-50% by weight), X-SBR (carboxylated styrene-butadiene copolymers), FKM (fluororubber), ABR (butadiene-C1-4-alkyl acrylate copolymers), ACM (acrylate rubber), NBR (butadiene-acrylonitrile copolymers with acrylonitrile contents of 5-60% by weight, preferably 10-50% by weight), X-NBR (carboxylated nitrile rubbers), CR (polychloroprene), IIR (isobutylene-isoprene copolymers with isoprene contents of 0.5-10% by weight), BIIR (bromated isobutylene-isoprene copolymers with bromine contents of 0.1-10% by weight), CIIR (chlorinated isobutylene-isoprene copolymers with chlorine contents of 0.1-10% by weight), HNBR (partially and/or fully hydrogenated nitrile rubbers), EPDM (ethylene-propylene-diene copolymers), EAM (ethylene-acrylate copolymers), EVM (ethylene-vinyl acetate copolymers), CO and ECO (epichlorohydrin rubbers), Q (silicone rubbers), AU (polyester urethane polymers), EU (polyether urethane polymers), ENR (epoxidized natural rubber) and mixtures thereof.  
   
   
       16 . The vulcanizable composition according to  claim 1  or  2 , comprising 
 a) 100 parts by weight of one or more hydrogenated nitrile rubbers,    b) from 1 to 100 parts by weight 
 of one or more unsaturated mono- or dicarboxylic acids having from 3 to 10 carbon atoms and/or of one or more salts thereof,  
   c) from 0.2 to 8 parts by weight 
 of one or more peroxides,  
   d) from 5 to 60 parts by weight 
 of one or more microgels, whose glass transition temperature T g  is below −20° C. and  
   e) from 0 to 100 parts by weight 
 of one or more conventional rubber additives.  
   
   
   
       17 . A process for the preparation of the vulcanizable compositions according to claims  1  or  2 , wherein the components a, b, c and d are mixed with one another.  
   
   
       18 . A process for the production of vulcanized products, wherein the vulcanizable composition according to  claim 1  or  2  is exposed to heat treatment.  
   
   
       19 . The process according to  claim 14 , wherein the vulcanizable composition according to  claim 1  or  2  is exposed in moulds to a temperature in the range from 120 to 200° C.  
   
   
       20 . A vulcanized product obtainable by the process of  claim 19  or  20 .  
   
   
       21 . The vulcanized product according to  claim 20  in the form of a drive belt, a roll covering, a gasket, a hose or a cable.