Process for the hydrogenation of a polymer composed of diene monomer units and nitrile group containing monomer units and hydrogenated polymer

Abstract

A polymer composition in solid form contains hydrogenated units of a polymer composed of diene monomer units and nitrile group containing monomer units. The hydrogenated polymer has an α/β peak ratio >1, measured by 1 H-NMR. The a peak is measured between 2.05 and 2.2 ppm. The β peak is measured between 1.8 and 2.05 ppm. The polymer composition has a gel content of less than 15 wt. % and a molecular weight distribution (of its soluble part) of less than 10. The polymer compositions may be used to form articles, such as automotive parts, which are less sensitive to oxidation degradation.

1 . Process for the hydrogenation of a polymer composed of diene monomer units and nitrile group containing monomer units, in which the hydrogenation in the form of an aqueous dispersion is carried out in the presence of hydrazine and an oxidizing compound characterized in that crosslinks formed as a result of the hydrogenation are broken by adding after the hydrogenation, a compound that satisfies formula I or by adding before, during or after the hydrogenation a compound that statisfies formula II  
       
         
           
           
               
               
           
         
       
       where 
 R 1  is a hydrogen atom, an alkyl or cycloalkyl group with 1-30 carbon atoms, or an aromatic group with 6-30 carbon atoms and  
 R 2  is an alkyl or cycloalkyl group with 1-30 carbon atoms, or an aromatic group with 6-30 carbon atoms,  
 X is chosen from the group comprising -R 3 , —OR 4 , —SR 4 , —NR 5 R 6 , where R 3 , R 4  and R 5  are a hydrogen atom, an alkyl or cycloalkyl group with 1-30 carbon atoms or an aromatic group with 6-30 carbon atoms and R 6  is an alkyl or cycloalkyl group with 1-30 carbon atoms or an aromatic group with 6-30 carbon atoms  
 Y is chosen from the group comprising -R 7 , —OR 8 , —SR 8 , —NR 9 R 10  and —N═CR 11 R 12 , where R 7 , R 8 , R 9 , R 10 , R 11  and R 12  are a hydrogen atom, an alkyl or cycloalkyl group with 1-30 carbon atoms or an aromatic group with 6-30 carbon atoms, and it being possible for R 3 -R 12  to also contain one or more heteroatoms from the groups 13, 14, 15, 16 or 17 of the Periodic System of the Elements.  
 
     
     
         2 . Process according to  claim 1 , characterized in that R 1  is a hydrogen atom.  
     
     
         3 . Process according to  claim 2 , characterized in that hydroxylamine is used as the compound that satisfies formula I.  
     
     
         4 . Process according to  claim 3 , characterized in that crumb of the hydrogenated polymer is contacted with a 1-10 wt. % solution of hydroxylamine in water.  
     
     
         5 . Process according to  claim 1 , characterized in that use is made of a compound that satisfies formula II with Y being an OH group.  
     
     
         6 . Process according to either of claims  1  or  5 , characterized in that the compound satisfies formula II with Y being an OH group, R1 a hydrogen atom and R2 an alkyl or cycloalkyl group with 1-15 carbon atoms or an aryl group with 6-10 carbon atoms.  
     
     
         7 . Process according to any one of claims  1 - 6 , characterized in that the compound that satisfies formula II, where Y is an OH group, R 1  a hydrogen atom and R 2  an alkyl or cycloalkyl group with 1-15 carbon atoms or an aryl group with 6-10 carbon atoms, is added before or during the hydrogenation and in that hydroxylamine is added during post-treatment of the hydrogenated polymer crumb.  
     
     
         8 . Process according to  claim 7 , characterized in that the hydrogenated polymer is kneaded at elevated temperature.  
     
     
         9 . Process according to  claim 8 , characterized in that the temperature at which the hydrogenated polymer is kneaded lies between 100 and 200° C.  
     
     
         10 . Process according to claims  8 - 9 , characterized in that an o-aromatic diamine is used as the compound that satisfies formula I in combination with a ketone.  
     
     
         11 . Polymer composition in solid form that contains hydrogenated polymer composed of diene monomer units and nitrile group containing monomer units, characterized in that the hydrogenated polymer has an α/β peak ratio >1, measured by means of  1 H-NMR, the α peak having been measured between 2.05 and 2.2 ppm and the β peak having been measured between 1.8 and 2.05 ppm, a gel content of less than 15 wt. % and a molecular weight distribution (Mw/Mn, measured using gel permeation chromatography) of the soluble part of the polymer composition of <10.  
     
     
         12 . Polymer composition according to  claim 11 , characterized in that the gel content is less than 10 wt. %.