Aqueous quenching media and use thereof in quenching metal substrates

Abstract

Aqueous media for quenching metal substrates are provided and contain (i) a polyvinylpyrrolidone/polyvinylcaprolactam copolymer and (ii) one or more of a second polymer, which is selected from (a) a substituted oxazoline polymer; (b) a poly(oxyethylene-oxyalkylene) glycol; or (c) a polyvinylpyrrolidone polymer. The quenching bath provides reduced cooling rates through the martensite temperature ranges. Also provided are processes for quenching metal substrates using these quenching media.

1 . A process for quenching heated metal substrate, comprising quenching said heated metal substrate with an aqueous quenching medium comprising:
 (i) a non-ionic, water-soluble or water-dispersible polyvinylpyrrolidone/polyvinylcaprolactam copolymer; and   (ii) a non-ionic, water-soluble or water-dispersible polymer comprising one or more of a polymer comprising:
 (a) a substituted oxazoline polymer; 
 (b) a poly(oxyethyleneoxyalkylene) glycol polymer; or 
 (c) a polyvinylpyrrolidone polymer. 
   
     
     
         2 . The process according to  claim 1 , wherein component (i) is of formula I: 
       
         
           
           
               
               
           
         
       
       wherein:
 R is an organic radical which does not significantly alter the nonionic, water-solubility, and water-dispersibility characteristic of said vinylpyrrolidone/vinylcaprolactam polymer; 
 n and m are, independently, integers, provided that said polymer of component (i) has a molecular weight of about 5,000 to about 2,000,000 and a K-value of about 60 to about 70. 
 
     
     
         3 . The process according to  claim 2 , wherein R is an alkyl, alkenyl, or alkynyl comprising one or more heteroatoms in the backbone of said alkyl, alkenyl, alkynyl. 
     
     
         4 . The process according to  claim 2 , wherein said copolymer (i) contains about 75% of n and about 25% of m. 
     
     
         5 . The process according to  claim 1 , wherein said polyvinylpyrrolidone/polyvinylcaprolactam copolymer (i) has a molecular weight of about 50,000 to about 1,000,000. 
     
     
         6 . The process according to  claim 1 , wherein component (ii) is said substituted oxazoline polymer (a) and is of formula II: 
       
         
           
           
               
               
           
         
       
       wherein:
 R 1  is an organic radical which does not significantly alter the nonionic and water soluble or water dispersible characteristics of said substituted oxazoline polymer (a); and 
 p is an integer, provided that the molecular weight of said oxazoline polymer (a) is about 5,000 to about 1,000,000. 
 
     
     
         7 . The process according to  claim 6 , wherein R 1  is aryl, aryl substituted with halogen, C 1  to C 7  alkyl, or C 1  to C 7  alkyl substituted with halogen. 
     
     
         8 . The process according to  claim 6 , wherein said oxazoline polymer (a) has a molecular weight of about 50,000 to about 500,000. 
     
     
         9 . The process according to  claim 1 , wherein component (ii) is said polyoxyethylene/polyoxyalkylene polymer (b) and is of formula III: 
       
         
           
           
               
               
           
         
       
       wherein:
 R 2  is an a chemical moiety that maintains the water solubility of said polymer (b); 
 x and y are integers, provided that said polymer (b) is water-soluble and said polyoxyethylene/polyoxyalkylene polymer has a molecular weight of about 1,000 to about 500,000. 
 
     
     
         10 . The process according to  claim 9 , wherein R 2  is an alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substituted alkynyl. 
     
     
         11 . The process according to  claim 1 , wherein component (ii) in said vinylpyrrolidone polymer (c) and is of formula IV: 
       
         
           
           
               
               
           
         
       
       wherein:
 z is an integer, provided that said vinylpyrrolidone polymer has a molecular weight of about 5,000 to about 3,500,000 and a K-value of about 26 to 130. 
 
     
     
         12 . The process according to  claim 11 , wherein said vinylpyrrolidone polymer (c) has a molecular weight of about 5,000 to about 1,000,000. 
     
     
         13 . The process according to  claim 1 , wherein the total concentration of components (i) and (ii) in said aqueous quenching medium is about 0.05% to about 5% by weight. 
     
     
         14 . The process according to  claim 1 , wherein said process further comprises one or more of a bacteriocidal agent, preservative, corrosion inhibitor, buffer, metal deactivator, and defoamer. 
     
     
         15 . The process according to  claim 1 , wherein the ratio of component (i) to component (ii) is about 90:10 to about 10:90. 
     
     
         16 . An aqueous quenching medium for heat-treating metal substrates, comprising:
 (i) a nonionic, water-soluble or water-dispersible substituted vinylpyrrolidone/vinylcaprolactam polymer of formula I:   
       
         
           
           
               
               
           
         
       
       wherein:
 R is an organic radical which does not significantly alter the nonionic, water-solubility, and water-dispersibility characteristic of said vinylpyrrolidone/vinylcaprolactam polymer; 
 n and m are independently integers, provided that said polymer of component (i) has a molecular weight of from about 5,000 to about 1,000,000 and a K-value of about 60 to about 70; and 
 wherein said vinylpyrrolidone/vinylcaprolactam copolymer has a vinylpyrrolidone component of about 10 to about 90 mol %, said copolymer has a vinylcaprolactam component of about 90 to about 10 mol %, and the sum of said vinylpyrrolidone and vinylcaprolactam components is 100 mol %; and 
 (ii) one of more polymers selected from the group consisting of:
 (a) a nonionic, water soluble or water dispersible substituted oxazoline polymer having formula I: 
 
 
       
         
           
           
               
               
           
         
         wherein:
 R 1  is an organic radical which does not significantly alter the nonionic and water soluble or water dispersible characteristics of said substituted oxazoline polymer; 
 p is an integer, provided that the molecular weight of said oxazoline polymer is about 50,000 to about 1,000,000; 
 (b) a polyoxyethylene/polyoxyalkylene polymer having formula III: 
 
       
       
         
           
           
               
               
           
         
         wherein:
 R 2  is an alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substituted alkynyl; 
 x and y are integers, provided that said polymer (b) is water-soluble and said polyoxyethylene/polyoxyalkylene polymer has a molecular weight of about 1,000 to about 500,000; and 
 (c) a vinylpyrrolidone polymer having formula IV: 
 
       
       
         
           
           
               
               
           
         
         wherein:
 z is an integer, provided that said vinylpyrrolidone polymer has a molecular weight of about 5,000 to about 3,500,000 and a K-value of about 26 to 130. 
 
       
     
     
         17 . The quenching medium according to  claim 16 , wherein the total concentration of components (i) and (ii) in said quenching medium is about 0.05% to 5%, by weight; said vinylpyrrolidone/vinylcaprolactam polymer has a molecular weight of about 50,000 to about 1,000,000; and said oxazoline has a molecular weight of about 50,000 to about 500,000. 
     
     
         18 . The quenching medium according to  claim 16 , wherein the total concentration of components (i) and (ii) in said quenching medium is about 0.05% to about 1.5%; said vinylpyrrolidone/vinylcaprolactam polymer has a molecular weight of about 100,000 to about 200,000; and said oxazoline polymer has a molecular weight of about 200,000 to about 500,000. 
     
     
         19 . The quenching medium according to  claim 16 , wherein the total concentration of components (i) and (ii) in said quenching medium is about 0.05% to about 5%, by weight, based on the total weight of the quenching medium; said (a) vinylpyrrolidone/vinylcaprolactam copolymer has a molecular weight of about 50,000 to about 1,000,000; and said polyoxyethylene/polyoxyalkylene polymer has a molecular weight of about 1,000 to about 500,000. 
     
     
         20 . The quenching medium according to  claim 16 , wherein the total concentration of components (i) and (ii) in said quenching medium is about 0.05% to about 1.5%; said vinylpyrrolidone/vinylcaprolactam copolymer has a molecular weight of about 100,000 to about 200,000; and said polyoxyethylene/polyoxyalkylene polymer has a molecular weight of about 5,000 to about 100,000. 
     
     
         21 . The quenching medium according to  claim 16 , wherein the total concentration of components (i) and (ii) in said quenching medium is about 0.05% to about 5%, by weight, based on the total weight of the quenching medium; said vinylpyrrolidone/vinylcaprolactam copolymer has a molecular weight of about 50,000 to about 1,000,000; and said vinylpyrrolidone polymer has a molecular weight of about 5,000 to about 1,000,000. 
     
     
         22 . The quenching medium according to  claim 16 , wherein the total concentration of components (i) and (ii) in said quenching medium is about 0.05% to about 1.5%; said vinylpyrrolidone/vinylcaprolactam copolymer has a molecular weight of about 100,000 to about 200,000; and said vinylpyrrolidone polymer has a molecular weight of about 5,000 to about 1,000,000. 
     
     
         23 . A concentrate for preparing an aqueous quenching medium useful in the heat treatment of metal substrates comprising at least about 5% by weight, of a mixture of:
 (i) a nonionic, water-soluble or water-dispersible substituted vinylpyrrolidone/vinylcaprolactam polymer of formula I:   
       
         
           
           
               
               
           
         
       
       wherein:
 R is an organic radical which does not significantly alter the nonionic, water-solubility, and water-dispersibility characteristic of said vinylpyrrolidone/vinylcaprolactam polymer; 
 n and m are independently integers, provided that said polymer of component (i) has a molecular weight of from about 5,000 to about 1,000,000 and a K-value of about 60 to about 70; and 
 wherein said vinylpyrrolidone/vinylcaprolactam copolymer has a vinylpyrrolidone component of about 10 to about 90 mol %, said copolymer has a vinylcaprolactam component of about 90 to about 10 mol %, and the sum of said vinylpyrrolidone and vinylcaprolactam components is 100 mol %; and 
 (ii) one of more polymers selected from the group consisting of:
 (a) a nonionic, water soluble or water dispersible substituted oxazoline polymer having formula II: 
 
 
       
         
           
           
               
               
           
         
         wherein:
 R 1  is an organic radical which does not significantly alter the nonionic and water soluble or water dispersible characteristics of said substituted oxazoline polymer; 
 p is an integer, provided that the molecular weight of said oxazoline polymer is about 50,000 to about 1,000,000; 
 
         (b) a polyoxyethylene/polyoxyalkylene polymer having formula III: 
       
       
         
           
           
               
               
           
         
         wherein:
 R 2  is an alkyl substituted alkyl alkenyl, substituted alkenyl, alkynyl, or substituted alkynyl; 
 x and y are integers, provided that said polymer (b) is water-soluble and said polyoxyethylene/polyoxyalkylene polymer has a molecular weight of about 1,000 to about 500,000; and 
 (c) a vinylpyrrolidone polymer having formula IV: 
 
       
       
         
           
           
               
               
           
         
         wherein:
 z is an integer, provided that said vinylpyrrolidone polymer has a molecular weight of about 5,000 to about 3,500,000 and a K-value of about 26 to 130. 
 
       
     
     
         24 . The concentrate according to  claim 23 , wherein the concentration of components (i) and (ii) is about 5% to 70%; said vinylpyrrolidone/vinylcaprolactam copolymer has a molecular weight of about 50,000 to about 1,000,000; and said oxazoline has a molecular weight of about 50,000 to about 500,000.