Process for chlorinating ethylene polymers

Abstract

A process for chlorinating solid, finely-divided ethylene polymers is disclosed, wherein the resulting chloropolyethylene has a statistical or hybridical distribution of chlorine in the polymer. The polymer is mixed with 10 - 100% by weight of water, based on the weight of the ethylene polymer, and the polymer is chlorinated with chlorine at a temperature which is above the crystalline melting point of the ethylene polymer during .[.at least 70%.]. .Iadd.a portion .Iaddend.of the chorination period. The chlorination pressure is such that the boiling point of water at that pressure is at least equal to the chlorination temperature. The amount of water in the ethylene polymer is maintained at a level of at least 10% by weight based on starting ethylene polymer until the chlorination has proceeded at least to the point where the chlorine content of the polymer is 15% by weight. The resulting chloropolyethylenes are useful in applications wherein previous chloropolyethylenes have been used, such as for mixing with synthetic polymers to improve the properties thereof.

What is claimed is: 
     
       1. Process for chlorinating a solid, finely divided ethylene polymer to produce statistical or hybridical chloropolyethylene, said process comprising a. mixing said polymer with 10 to 100% by weight of water, based on the weight of ethylene polymer, and   b. chlorinating the polymer with gaseous chlorine at a temperature which is below the ethylene polymer decomposition temperature and above the crystalline melting point of the ethylene polymer during .[.at least about 70%.]. .Iadd.a part .Iaddend.of the chlorination period and at a pressure such that the boiling point of water at said pressure is at least equal to the said chlorination temperature while maintaining the amount of water in the ethylene polymer at a level of at least 10% by weight, based on the weight of starting ethylene polymer, until the chlorination has proceeded to a polymer chlorine content of at least 15% by weight and maintaining the water substantially uniformly distributed in the polymer.   
     
     
       2. Process according to claim 1, wherein the chlorination is conducted in the presence of a chlorination reaction initiator or radiation which initiates the chlorination reaction. 
     
     
       3. Process according to claim 1, wherein the chlorination temperature is below the softening point of the starting ethylene polymer at least during the chlorination to a polymer chlorine content of 15% by weight. 
     
     
       4. Process according to claim 1, wherein at least 10% by weight of water is present, based on the weight of starting ethylene polymer, until the chlorination has proceeded to a polymer chlorine content of at least 20% by weight. 
     
     
       5. Process according to claim 1, wherein from 0.05 - 1% by weight of a wetting agent, based on the weight of water, is incorporated in the ethylene polymer/water system. 
     
     
       6. Process according to claim 5, wherein no more than 0.1% by weight of the wetting agent, based on the weight of the water, is used. 
     
     
       7. Process according to claim 1, wherein at least 1 strong acid or strong acid salt electrolyte is incorporated in the ethylene/polymer water system in an amount of at most 50% by weight of electrolyte, based on the weight of the water. 
     
     
       8. Process according to claim 7, wherein at least 1% by weight of the electrolyte is used. 
     
     
       9. Process according to claim 1, wherein water which is evaporated during the chlorination is condensed and returned to the chlorination zone during at least a portion of the chlorination reaction. 
     
     
       10. Process according to claim 1, wherein the water which is evaporated in the chlorination zone during the chlorination reaction is discharged from said zone. 
     
     
       11. Process according to claim 1, wherein the chlorination is continued until the resulting chlorinated ethylene polymers have a chlorine content of from 10 to about 50% by weight. 
     
     
       12. Process according to claim 11, wherein said chlorine content is 30 - 48% by weight. 
     
     
       13. Process according to claim 10, wherein at least during the latter portion of the chlorination reaction, water is removed so that the final chlorinated ethylene polymer is obtained in a dry state. 
     
     
       14. Process according to claim 1, wherein the degree of suspension of the ethylene/polymer water mixture is from 50 - 65 during at least a portion of the chlorination reaction. 
     
     
       15. Process according to claim 1, wherein the chlorination temperature is above the crystalline melting point of the ethylene polymer during substantially all of the chlorination period.