Self-extinguishing cable and flame-retardant composition used therein

Abstract

A self-extinguishing cable and the flame-retardant composition used therein are disclosed. The cable comprises at least one flame-retardant coating comprising a) at least one polymer material; b) at least one inorganic hydrated flame-retardant filler; and c) at least one silane substituted with at least one C 10 -C 40 hydrocarbon group and with at least one hydrolysable group. The self-extinguishing cable shows improved insulating properties in water or in the presence of a moist environment without adversely affecting self-extinguishing properties.

1 . Self-extinguishing cable comprising at least one conductor and at least one flame-retardant coating, wherein the at least one flame-retardant coating comprises: 
 a) at least one polymer material selected from: olefin homopolymers, olefin copolymers, copolymers of at least one olefin with at least one ethylenically unsaturated ester, polyesters, polyethers, polyether/polyester copolymers, and mixtures thereof;    b) at least one inorganic hydrated flame-retardant filler;    c) at least one silane substituted with at least one C 10 -C 40  hydrocarbon group and with at least one hydrolysable group.    
     
     
         2 . A cable according to  claim 1 , wherein the polymer material is selected from: 
 polyethylene; copolymers of ethylene with at least one α-olefin containing from 3 to 12 carbon atoms, and optionally with at least one diene containing from 4 to 20 carbon atoms; polypropylene; thermoplastic copolymers of propylene with ethylene and/or at least one α-olefin containing from 4 to 12 carbon atoms; copolymers of ethylene with at least one ester selected from alkyl acrylates, alkyl methacrylates and vinyl carboxylates, wherein the alkyl and the carboxylic groups comprised therein are linear or branched, and wherein the linear or branched alkyl group may contain from 1 to 8, preferably from 1 to 4, carbon atoms, while the linear or branched carboxylic group may contain from 2 to 8, preferably from 2 to 5, carbon atoms; and mixtures thereof.    
     
     
         3 . A cable according to  claim 2 , wherein the linear or branched alkyl group may contain from 1 to 4 carbon atoms, while the linear or branched carboxylic group may contain from 2 to 5 carbon atoms.  
     
     
         4 . A cable according to any of the previous claims, wherein the polymer material is selected from copolymers of ethylene with at least one α-olefin containing from 3 to 12 carbon atoms, and optionally with at least one diene containing from 4 to 20 carbon atoms, obtained by single-site catalysis.  
     
     
         5 . A cable according to any of the previous claims, wherein the inorganic hydrated flame-retardant filler is selected from: metal hydroxides, hydrated metal oxides, metal salts having at least one hydroxyl group, and hydrated metal salts.  
     
     
         6 . A cable according to any of the previous claims, wherein the inorganic hydrated flame-retardant filler is a calcium, aluminium, magnesium or zinc hydroxide, hydrated oxide, salt having at least one hydroxyl group or hydrated salt.  
     
     
         7 . A cable according to any of the previous claims, wherein the flame-retardant filler is selected from: magnesium hydroxide, alumina trihydrate, hydrated magnesium carbonate, hydrated calcium, magnesium carbonate, 4ZnO.B 2 O 3 .H 2 O, 2ZnO.3B 2 O 3 .3.5H 2 O, or mixtures thereof.  
     
     
         8 . A cable according to any of the previous claims, wherein the flame-retardant filler is magnesium hydroxide.  
     
     
         9 . A cable according to any of the previous claims, wherein the C 10 -C 40  hydrocarbon group contained in the silane is a C 10 -C 40  alkyl, alkenyl, aryl, alkylaryl, arylalkyl, arylalkenyl, alkenylaryl group, whereas the hydrolysable group is a C 1 -C 16  alkoxy group, optionally substituted by at least one C 1 -C 16  alkoxy group.  
     
     
         10 . A cable according to any of the previous claims, wherein the C 10 -C 40  hydrocarbon group contained in the silane is a C 12 -C 24  alkyl, alkenyl, aryl, alkylaryl, arylalkyl, arylalkenyl, alkenylaryl group.  
     
     
         11 . A cable according to any of the previous claims, wherein the silane has the following formula: 
       Y 4−(x+z) SiR x R′ z   (I) 
       wherein: 
 x is 1, 2 or 3; z is zero, 1 or 2; with the proviso that x+z is not higher than 3;  
 Y, equal or different from each other, are C 1 -C 8  alkoxy groups, optionally substituted by at least one C 1 -C 8  alkoxy group;  
 R, equal or different from each other, are selected from: 
 C 10 -C 40  alkyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 10 -C 40  alkenyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 6 -C 14  aryl groups, optionally substituted by at least one C 1 -C 30  alkyl group and/or by at least one C 2 -C 30  alkenyl group;  
 with the proviso that each of R has from 10 to 40 carbon atoms;  
 
 R′, equal or different from each other, are selected from: 
 hydrogen;  
 C 1 -C 20  alkyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 2 -C 20  alkenyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 6 -C 14  aryl groups, optionally substituted by at least one C 1 -C 20  alkyl group and/or by at least one C 2 -C 20  alkenyl group.  
 
 
     
     
         12 . A cable according to any of the previous claims, wherein the silane has the following formula: 
       Y 4−(x+z)SiR   x R′ z   (I) 
       wherein: 
 x is 1, 2 or 3; z is zero, 1 or 2; with the proviso that x+z is not higher than 3;  
 Y, equal or different from each other, are C 1 -C 4  alkoxy groups, optionally substituted by at least one C 1 -C 4  alkoxy group;  
 R, equal or different from each other, are selected from: 
 C 12 -C 24  alkyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 12 -C 24  alkenyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 6 -C 10  aryl groups, optionally substituted by at least one C 1 -C 30  alkyl group and/or by at least one C 2 -C 30  alkenyl group;  
 with the proviso that each of R has from 10 to 40 carbon atoms;  
 
 R′, equal or different from each other, are selected from: 
 hydrogen;  
 C 1 -C 16  alkyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 2 -C 16  alkenyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 6 -C 10  aryl groups, optionally substituted by at least one C 1 -C 20  alkyl group and/or by at least one C 2 -C 20  alkenyl group.  
 
 
     
     
         13 . A cable according to any of the previous claims, wherein the silane has the following formula: 
       Y 4−(x+z) SiR x R′ z   (I) 
       wherein: 
 x is 1, 2 or 3; z is zero, 1 or 2; with the proviso that x+z is not higher than 3;  
 Y, equal or different from each other, are C 1 -C 4  alkoxy groups, optionally substituted by at least one C 1 -C 4  alkoxy group;  
 R, equal or different from each other, are selected from: 
 C 14 -C 20  alkyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 14 -C 20  alkenyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 6 -C 10  aryl groups, optionally substituted by at least one C 1 -C 30  alkyl group and/or by at least one C 2 -C 30  alkenyl group;  
 with the proviso that each of R has from 10 to 40 carbon atoms;  
 
 R′, equal or different from each other, are selected from: 
 hydrogen;  
 C 1 -C 12  alkyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 2 -C 12  alkenyl groups, optionally substituted by at least one C 6 -C 14  aryl group;  
 C 6 -C 10  aryl groups, optionally substituted by at least one C 1 -C 20  alkyl group and/or by at least one C 2 -C 20  alkenyl group.  
 
 
     
     
         14 . A cable according to any of the claims  11 - 13 , wherein, in formula (I), x is 1; z is zero; Y, equal or different from each other, are selected from C 1 -C 4  alkoxy group, optionally substituted by at least one C 1 -C 4  alkoxy group; R is a C 14 -C 20  alkyl.  
     
     
         15 . A cable according to any of the claims  11 - 14 , wherein, in formula (I), x is 1; z is zero; Y, equal or different from each other, are selected from methoxy, ethoxy or methoxyethoxy group, optionally substituted by at least one methoxy, ethoxy or methoxyethoxy group and R is a hexadecyl or octadecyl group.  
     
     
         16 . A cable according to any of the previous claims, wherein the silane is in an amount from 0.1% to 10% with respect to the total weight of the inorganic flame-retardant filler.  
     
     
         17 . A cable according to any of the previous claims, wherein the silane is in an amount from 0.5% to 5% by weight with respect to the total weight of the inorganic flame-retardant filler.  
     
     
         18 . Flame-retardant composition comprising: a) at least one polymer material; b) at least one inorganic hydrated flame-retardant filler; and c) at least one silane; a), b) and c) being defined according to any of the previous claims.