Process For Preparing Graft Polymers Without Initiator And Without Solvent And Bitumen/Polymer Compositions Comprising Said Graft Polymers

Abstract

A process for preparing graft polymers from a polymer is based on conjugated diene units and a graft which is a thiol derivative. The process has an absence of solvent and any radical initiator. The graft polymer can be advantageously be used as additive for a bitumen/polymer composition and in particular permits thermoreversible cross-linking.

The invention claimed is: 
     
         1 . A process for preparing a bitumen/polymer composition, comprising mixing a graft polymer with bitumen at a temperature comprised between 100° C. and 200° C. for a duration of 30 minutes to 4 hours, the graft polymer being obtained in the absence of solvent and of a source of radicals by a process comprising:
 (i) bringing a thiol derivative into contact with a polymer based on conjugated diene units at a temperature comprised between 20° C. and 120° C., for a duration of 10 minutes to 24 hours, to create a mixture; and then 
 (ii) heating the mixture at a temperature comprised between 80° C. and 200° C. for a duration of 10 minutes to 48 hours. 
 
     
     
         2 . The process of preparation according to  claim 1 , wherein mixing the graft polymer with bitumen is performed at a temperature between 120° C. and 180° C. 
     
     
         3 . The process of preparation according to  claim 1 , wherein mixing the graft polymer with bitumen is performed for a duration of 1 hour and 2 hours. 
     
     
         4 . The process of preparation according to  claim 1 , wherein the temperature of step (i) is between 30° C. and 110° C. 
     
     
         5 . The process of preparation according to  claim 1 , wherein the duration of step (i) is between 30 minutes and 12 hours. 
     
     
         6 . The process of preparation according to  claim 1 , wherein the temperature of step (ii) is between 100° C. and 160° C. 
     
     
         7 . The process of preparation according to  claim 1 , wherein the duration of step (ii) is between 30 minutes and 24 hours. 
     
     
         8 . The process of preparation according to  claim 1 , further comprising purifying the graft polymer after step (ii). 
     
     
         9 . The process of preparation according to  claim 1 , wherein steps (i) and/or (ii) and/or the step of mixing the graft polymer with bitumen are carried out with stirring. 
     
     
         10 . The process of preparation according to  claim 1 , wherein the thiol derivative has the general formula C n H 2n+1 —SH, where n is an integer comprised between 12 and 110. 
     
     
         11 . The process of preparation according to  claim 1 , wherein the polymer is a copolymer based on conjugated diene units and aromatic monovinyl hydrocarbon units. 
     
     
         12 . The process of preparation according to  claim 11 , wherein the aromatic monovinyl hydrocarbon is chosen from the group consisting of styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,3-dimethylstyrene, α-methylstyrene, vinyl naphthalene, vinyl toluene, vinyl xylene, and mixtures thereof. 
     
     
         13 . The process of preparation according to  claim 1 , wherein the conjugated diene is chosen from the group consisting of butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,2-hexadiene, chloroprene, carboxylated butadiene, carboxylated isoprene, and mixtures thereof. 
     
     
         14 . The process of preparation according to  claim 1 , wherein the polymer based on conjugated diene units has a content of units with 1,2 double bonds originating from the conjugated diene between 5 and 50 wt. %, relative to the total weight of the conjugated diene units. 
     
     
         15 . The process of preparation according to  claim 1 , wherein the molar ratio of the quantity of thiol derivative to the quantity of units with 1,2 double bonds originating from the conjugated diene is comprised between 0.01 and 5. 
     
     
         16 . The process of preparation according to  claim 1 , wherein the temperature of step (i) is between 40° C. and 100° C. and the temperature of step (ii) is between 120° C. and 140° C. 
     
     
         17 . The process of preparation according to  claim 1 , wherein the graft polymer has a polydispersity index between 1 and 4. 
     
     
         18 . The process of preparation according to  claim 1 , wherein the graft polymer has a polydispersity index comprised between 1.1 and 3. 
     
     
         19 . A process for preparing a bitumen/polymer composition, comprising:
 (i) bringing a thiol derivative into contact with a polymer based on conjugated diene units at a temperature between 20° C. and 120° C., for a duration of 10 minutes to 24 hours, to create a mixture;   (ii) heating the mixture at a temperature between 80° C. and 200° C. for a duration of 10 minutes to 48 hours to create a graft polymer, wherein steps (i) and (ii) are carried out in the absence of a solvent and of a source of radicals; and   (iii) mixing the graft polymer with bitumen at a temperature between 100° C. and 200° C. for a duration of 30 minutes to 4 hours to create the bitumen/polymer composition.   
     
     
         20 . The process of preparation according to  claim 19 , wherein the polymer is a copolymer based on conjugated diene units and aromatic monovinyl hydrocarbon units. 
     
     
         21 . A process for preparing a bitumen/polymer composition, comprising:
 (i) bringing a thiol derivative into contact with a copolymer based on conjugated diene units and aromatic monovinyl hydrocarbon units at a temperature between 20° C. and 120° C., for a duration of 10 minutes to 24 hours, to create a mixture;   (ii) heating the mixture at a temperature between 80° C. and 200° C. for a duration of 10 minutes to 48 hours to create a graft polymer having a polydispersity index between 1 and 4, wherein steps (i) and (ii) are performed in the absence of a solvent and of a source of radicals;   (iii) purifying the graft polymer to create a purified graft polymer; and   (iv) mixing the purified graft polymer with bitumen at a temperature between 100° C. and 200° C. for a duration of 30 minutes to 4 hours to create the bitumen/polymer composition.   
     
     
         22 . The process of preparation according to  claim 19 , wherein the thiol derivative has the general formula C n H 2n+1 —SH, where n is an integer comprised between 12 and 110, the conjugated diene units comprise butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,2-hexadiene, chioroprene, carboxylated butadiene, carboxylated isoprene, or mixtures thereof, and the aromatic monovinyl hydrocarbon units comprise styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,3-dimethylstyrene, α-methylstyrene, vinyl naphthalene, vinyl toluene, vinyl xylene, or mixtures thereof.