Low viscosity polymer polyols characterized by a high hydroxyl number

Abstract

The present invention relates to novel polymer polyols which have low viscosities and high hydroxyl numbers, and to a process for the preparation of these novel polymer polyols. These polymer polyols have hydroxyl numbers of ≧20, solids contents of about 30 to about 65% by weight and a viscosity that is less than or equal to: be [2.7c] . These comprise the reaction product of a base polyol, a preformed stabilizer and at least one ethylenically unsaturated monomer, in the presence of a free-radical polymerization initiator and at least one polymer control agent. The base polyol has a hydroxyl number of 60 to 1900, a functionality of 1 to 10, and an equivalent weight of 30 to 900.

1 . A stable, low-viscosity polymer polyol having a hydroxyl number of ≧20, a viscosity that is less than or equal to: 
 be [2.7c] 
 wherein: 
 b represents the base polyol viscosity, and  
 c represents [wt. % solids in polymer polyol/(100−wt. % solids in polymer polyol)],  
 having a solids content of about 30% to about 65% by weight, based on the total weight of the polymer polyol, comprising the reaction product of:  
 
   (A) a base polyol having a hydroxyl number of from about 60 to about 1900, a functionality of about 1 to about 10, and an equivalent weight of about 30 to about 900,    (B) a preformed stabilizer, and    (C) at least one ethylenically unsaturated monomer, in the presence of    (D) a free-radical polymerization initiator, and    (E) at least one polymer control agent.    
   
   
       2 . The stable, low-viscosity polymer polyol of  claim 1  which is characterized by a hydroxyl number of at least about 35.  
   
   
       3 . The stable, low-viscosity polymer polyol of  claim 1 , wherein (A) said base polyol has a hydroxyl number of from about 70 to about 600, a functionality of about 2 to about 6, and an equivalent weight of from about 100 to about 600.  
   
   
       4 . The stable, low-viscosity polymer polyol of  claim 1 , wherein (A) said base polyol has an OH number of about 90 to about 400, a functionality of about 2 to about 3, and an equivalent weight of about 200 to about 500.  
   
   
       5 . The stable, low-viscosity polymer polyol of  claim 1 , wherein (C) said ethylenically unsaturated monomer comprises a mixture of styrene and acrylonitrile.  
   
   
       6 . The stable, low-viscosity polymer polyol of  claim 1 , wherein styrene and acrylonitrile are present in a weight ratio of from 80:20 to 40:60.  
   
   
       7 . The stable, low-viscosity polymer polyol of  claim 1 , wherein (D) said free-radical polymerization initiator is selected from the group consisting of azo compounds, peroxide compounds and mixtures thereof.  
   
   
       8 . The stable, low-viscosity polymer polyol of  claim 7 , wherein said azo compounds are selected from the group consisting of azobis(isobutyronitrile), 2,2′-azo bis(2-methylbutyronitrile) and mixtures thereof.  
   
   
       9 . The stable, low-viscosity polymer polyol of  claim 7 , wherein said peroxide compounds are selected from the group consisting of acyl peroxides, alkyl peroxides, persulfates, perborates, percarbonates and mixtures thereof.  
   
   
       10 . The stable, low-viscosity polymer polyol of  claim 1 , wherein said polymer control agent comprises one or more alcohols containing at least one carbon atom.  
   
   
       11 . The stable, low-viscosity polymer polyol of  claim 10 , wherein said polymer control agent comprises isopropanol.  
   
   
       12 . The stable, low-viscosity polymer polyol of  claim 1  which is characterized by a hydroxyl number of at least about 50.  
   
   
       13 . A process for preparing a stable, low-viscosity polymer polyol having a hydroxyl number of ≧20, a viscosity that is less than or equal to: 
 be [2.7c] 
 wherein: 
 b represents the base polyol viscosity, and  
 c represents [wt. % solids in polymer polyol/(100−wt. % solids in polymer polyol)],  
 and a solids content of about 30% to about 65% by weight, based on the total weight of the polymer polyol, comprising  
 
   (1) reacting: 
 (A) a base polyol having a hydroxyl number of from about 60 to about 1900, a functionality of about 1 to about 10, and an equivalent weight of about 30 to about 900,  
 (B) a preformed stabilizer, and  
 (C) at least one ethylenically unsaturated monomer, in the presence of  
 (D) a free-radical polymerization initiator, and  
 (E) at least one polymer control agent.  
   
   
   
       14 . The process of  claim 13  in which the stable, low-viscosity polymer polyol is characterized by a hydroxyl number of at least about 35.  
   
   
       15 . The process of  claim 13 , wherein (A) said base polyol has a hydroxyl number of from about 70 to about 600, a functionality of about 2 to about 6, and an equivalent weight of from about 100 to about 600.  
   
   
       16 . The process of  claim 13 , wherein (A) said base polyol has an OH number of about 90 to about 400, a functionality of about 2 to about 3, and an equivalent weight of about 200 to about 500.  
   
   
       17 . The process of  claim 13 , (C) said ethylenically unsaturated monomer comprises a mixture of styrene and acrylonitrile.  
   
   
       18 . The process of  claim 17 , wherein styrene and acrylonitrile are present in a weight ratio of from 80:20 to 40:60.  
   
   
       19 . The process of  claim 13 , wherein (D) said free-radical polymerization initiator is selected from the group consisting of azo compounds, peroxide compounds and mixtures thereof.  
   
   
       20 . The process of  claim 19 , wherein said azo compounds are selected from the group consisting of azobis(isobutyronitrile), 2,2′-azo bis(2-methylbutyronitrile) and mixtures thereof.  
   
   
       21 . The process of  claim 19 , wherein said peroxide compounds are selected from the group consisting of acyl peroxides, alkyl peroxides, persulfates, perborates, percarbonates and mixtures thereof.  
   
   
       22 . The process of  claim 13 , wherein said polymer control agent comprises one or more alcohols containing at least one carbon atom.  
   
   
       23 . The process of  claim 22 , wherein said polymer control agent comprises isopropanol.  
   
   
       24 . The process of  claim 13  in which the stable, low-viscosity polymer polyol is characterized by a hydroxyl number of at least about 50.  
   
   
       25 . The process of  claim 13  wherein the process comprises a semi-batch process.  
   
   
       26 . The process of  claim 13  wherein the process comprises a continuous process.  
   
   
       27 . In a process for the production of a polyurethane foam, comprising reacting a polyisocyanate with an isocyanate-reactive component, the improvement wherein the isocyanate-reactive component comprises the polymer polyol of  claim 1 .  
   
   
       28 . The polyurethane foam produced by the process of  claim 27.