Polyurethane adhesive for a surface treatment-free fiber reinforced plastic

Abstract

A two component type polyurethane adhesive is provided for fiberglass reinforced plastics which requires no cleaning, preparation or treatment of the surface, and the like. The curative component is a nitrogen-free liquid polyether or polyester in an amount such that in association with a urethane prepolymer component containing free NCO groups, the ratio of the free NCO groups in the prepolymer component to the OH groups in said curative component is at least 1.2 and desirably at least 1.35. Such high NCO/OH ratios have unexpectedly been found to provide good adhesion and especially good humidity adhesion and peel strength adhesion to fiberglass reinforced plastics or metal surfaces which are free from any surface treatment.

What is claimed is:  
     
       1. A two component urethane adhesive, comprising: 
       a urethane prepolymer component and a curative component, said urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the amount  equivalent ratio of said polyisocyanate to the hydroxyl terminated intermediate being an equivalent excess of  at least 2.0 so that said prepolymer component has free NCO groups, said curative component comprising a nitrogen- free polyol curative which comprises  a nitrogen-free polyether polyol having OH groups, a nitrogen-free polyester polyol having OH groups  a nitrogen-free low molecular weight  polyol, or combinations thereof and a primary polyamine, the amount of said polyol  curative being such that the equivalents ratio of said free NCO groups to said OH  hydroxy groups and NH  amine groups of said curative component is from about 1.2 to about 2.0, the two component urethane adhesive being capable of bonding to a surface treatment-free plastic, fiber reinforced plastic, or metal.  
     
     
       2. A two component urethane adhesive according to claim  1 , wherein said hydroxyl terminated intermediate is a polyester polyol or a polyether polyol having a number average molecular weight of from about 400 to about 10,000, wherein said polyisocyanate has the formula R(NCO) n  where n is an integer of 2, 3 or 4, wherein R is an aliphatic having from 2 to about 20 carbon atoms, an aromatic or an alkyl substituted aromatic having from 6 to 20 carbon atoms, and  or combinations of said polyisocyanate. 
     
     
       3. A two component urethane adhesive according to claim  2 , wherein said polyether polyol intermediate  is made from an alkylene oxide having from 2 to 10 carbon atoms, wherein said polyester polyol intermediate  is made from a polyhydric alcohol having from 2 to 15 carton atoms and a polycarboxylic acid having from 2 to 14 carbon atoms, wherein R of said polyisocyanate is an aromatic or an alkyl substituted aromatic having from 6 to 15 carbon atoms, and wherein said curative compound is a liquid. 
     
     
       4. A two component urethane adhesive according to claim  3  wherein said equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate is from about 5.0 to about 10.0 based upon said hydroxyl terminated intermediate , wherein the equivalent excess  ratio of said free NCO groups to said OH  hydroxy and NH  amine groups of said curative component is from about 1.35 to about 1.6, and wherein said nitrogen-free low molecular weight  polyol curative is alkyl diol having from 2 to 12 carbon atoms, a polyhydric alcohol having from 3 to 15 carbon atoms and from 3 to 8 hydroxyl groups, a carbohydrate having from 5 to 12 carbon atoms and from 4 to 10 hydroxyl groups, or combinations thereof. 
     
     
       5. A two component urethane adhesive according to claim  4 , wherein said polyether polyol intermediate  and said polyester polyol intermediate  has a number average molecular weight of from about 2,000 to about 4,000, wherein said polyol curative is said alkyl diol, said polyhydric alcohol or said carbohydrate, or combinations thereof, said urethane prepolymer component including a filler, the amount of said filler being from about 5 parts to about 100 parts by weight for every 100 parts by weight of said prepolymer component, and said curative component including a filler, the amount of said filler being from about 5 parts to about 100 parts by weight for every 100 parts by weight of said polyol curative. 
     
     
       6. A two component urethane adhesive according to claim  5 , wherein said hydroxyl terminated intermediate is polypropylene ether diol, polybutylene ether diol, polytetramethylene ether diol, polycaprolactone diol, and  or combinations thereof, wherein said equivalent ratio of said free NCO groups to said OH  hydroxy and NH  amine groups of said curative component is from about 1.35 to about 1.45 wherein said polyisocyanate is methylene diphenyl diisocyanate or toluene diisocyanate, and wherein said nitrogen-free low molecular weight  polyol curative is an ethylene or propylene oxide adduct of trimethylol propane, pentaerythritol, glycerol, an alkyl glucoside wherein said alkyl has from 1 to 12 carbon atoms, or combinations thereof. 
     
     
       7. A two component urethane adhesive according to claim  6 , wherein said filler of said prepolymer component and said curative component independently is ground mica, talc, kaolin clay, calcium sulfite, colloidal silica, wollastonite, ballotini, hallow glass microspheres, glass, carbon fibers, graphite fibers, zinc oxide, titanium oxide, zirconium oxide, ground quartz, a metallic silicate, lead powder, aluminum powder, bronze powder, or combinations thereof, wherein the amount of said filler in said prepolymer component is from about 20 parts to about 50 parts by weight for every 100 parts by weight of said prepolymer component, and wherein the amount of said filler in said curative component is from about 30 parts to about 60 parts by weight for every 100 parts by weight of said curative component, said prepolymer component including from about 0.1 to about 40 parts by weight for every 100 parts by weight  of a polyhydric alcohol having from 2 to 15 carbon atoms for every  100  parts by weight of said polyether polyol or said polyester polyol or both, said curative component containing from about 1 part to about 5 parts by weight for every 100 parts by weight  of said primary polyamine having from 1 to 14 carbon atoms for every  100  parts by weight of said curative. 
     
     
       8. A two component urethane adhesive according to claim  7 , wherein said filler of said prepolymer and said curative component is talc, and wherein the amount of said polyhydric alcohol in said prepolymer component is from about 0.1 to about 10 parts by weight for every 100 parts by weight of said polyol intermediate. 
     
     
       9. A urethane adhesive composite containing treatment-free substrates therein, comprising: 
       the urethane adhesive, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component, said urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate of said hydroxyl terminated intermediate being from about 2 to 20 so that said prepolymer component contains free NCO groups,  
       said urethane curative component containing a polyol curative having OH groups therein and a primary polyamine containing NH groups therein, the equivalent ratio of said free NCO groups to said OH groups of said polyol curative and said NH groups of said primary polyamine being at least 1.2, at least two surface treatment-free substrate, said substrates bonded together by said urethane adhesive.  
     
     
       10. A urethane adhesive composite according to claim  9 , wherein said hydroxyl terminated intermediate is a polyester polyol or a polyether polyol having a number average molecular weight of from about 400 to about 10,000, wherein said polyisocyanate has the formula R(NCO) n  where n is an integer of 2, 3 or 4, wherein R is an aliphatic having from 2 to about 20 carbon atoms, an aromatic or an alkyl substituted aromatic having from 6 to 20 carbon atoms, and combinations of said polyisocyanate. 
     
     
       11. A urethane adhesive composite according to claim  10 , wherein said substrate is a treatment-free fiber-glass reinforced plastic, a treatment-free metal, or a treatment-free plastic substrate. 
     
     
       12. A urethane adhesive composite according to claim  11 , wherein said polyether polyol intermediate is made from an alkylene oxide having from 2 to 10 carbon atoms, wherein said polyester polyol intermediate is made from a polyhydric alcohol having from 2 to 15 carbon atoms and a polycarboxylic acid having from 2 to 14 carbon atoms, wherein R of said polyisocyanate is an aromatic or an alkyl substituted aromatic having from 6 to 15 carbon atoms, wherein said equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate is from about 5.0 to about 10.0, wherein the equivalent ratio of said free NCO groups to said OH groups and said NH groups of said curative is from about 1.35 to about 1.6, and wherein said polyol curative is alkyl diol having from 2 to 12 carbon atoms, a polyhydric alcohol having from 3 to 15 carbon atoms and from 3 to 8 hydroxyl groups, a carbohydrate having from 5 to 12 carbon atoms and from 4 to 10 hydroxyl groups, or combinations thereof. 
     
     
       13. A urethane adhesive composite according to claim  12 , wherein said polyether polyol intermediate and said polyester polyol intermediate has a number average molecular weight of from about 2,000 to about 4,000, 
       wherein said hydroxyl terminated intermediate is polypropylene ether diol, polybutylene ether diol, polytetramethylene ether, polycaprolactone diol, and combinations thereof, wherein said equivalent ratio of said free NCO groups to said OH groups and said NH groups of said curative is from about 1.35 to about 1.45, wherein said polyisocyanate is methylene diphenyl diisocyanate or toluene diisocyanate, and wherein said polyol curative is an ethylene or propylene oxide adduct of trimethylol propane, pentaerythritol, glycerol, an alkyl glucoside wherein said alkyl has from 1 to 12 carbon atoms, or combinations thereof.  
     
     
       14. A urethane adhesive composite according to claim  13 , including a filler is said urethane prepolymer component, the amount of said filler being from about 5 parts to about 100 parts by weight of said prepolymer component, and including a filler in said curative component, the amount of said filler being from about 5 parts to about 100 parts by weight for every 100 parts by weight of said polyol curative. 
     
     
       15. A urethane adhesive composite according to claim  14 , wherein said filler of said prepolymer component and said curative component independently is ground mica, talc, kaolin clay, calcium carbonate, calcium sulfite, colloidal silica, wollastonite, bottotini, hollow glass microspheres, glass carbon fibers, graphite fibers, zinc oxide, titanium oxide, zirconium oxide, ground quartz, a metallic silicate, lead powder, aluminum powder, bronze powder, or combinations thereof, wherein the amount of said filler in said prepolymer component is from about 20 parts to about 50 parts by weight for every 100 parts by weight of said prepolymer component, and wherein the amount of said filler in said curative component is from about 30 parts to about 60 parts by weight for every 100 parts by weight of said polyol curative, said prepolymer component including from about 0.1 to about 40 parts by weight for every 100 parts by weight of a polyhydric alcohol having from 2 to 15 carbon atoms, said curative component containing from about 1 part to about 5 parts by weight for every 100 parts by weight of said primary polyamine having from 1 to 14 carbon atoms. 
     
     
       16. A urethane adhesive composite according to claim  14 , wherein said substrate is said treatment-free fiberglass reinforced plastic. 
     
     
       17. A process for adhering at least one treatment-free substrate to another substrate, comprising the steps of: 
       applying a two component urethane adhesive to at least a first treatment-free substrate, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component, said urethane prepolymer being made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being from about 2 to 20 so that said prepolymer component contains free NCO groups,  
       said urethane curative component containing a polyol curative having OH groups therein and a primary polyamine containing NH groups therein, the equivalent ratio of said free NCO groups to said OH groups and said NH groups of said polyol curative being at least 1.2,  
       applying said two component urethane adhesive to at least a second substrate, and  
       curing said two component urethane adhesive by heating.  
     
     
       18. A process according to claim  17 , wherein said second substrate is a treatment-free substrate, wherein said hydroxyl terminated intermediate is a polyester polyol or a polyether polyol having a number average molecular weight of from about 400 to about 10,000, wherein said polyisocyanate has the formula R(NCO) n  where n is an integer of 2, 3 or 4, wherein R is an aliphatic having from 2 to about 20 carbon atoms, an aromatic or an alkyl substituted aromatic having from 6 to 20 carbon atoms, and combinations of said polyisocyanate, and wherein said first and said second substrate is a treatment-free metal, or a treatment-free plastic substrate. 
     
     
       19. A process according to claim  18 , including curing said two component urethane adhesive by heating said adhesive to a temperature above 50° C., wherein said polyether polyol intermediate is made from an alkylene oxide having from 2 to 10 carbon atoms, wherein said polyester polyol intermediate is made from a polyhydric alcohol having from 2 to 15 carbon atoms and a polycarboxylic acid having from 2 to 14 carbon atoms, wherein R of said polyisocyanate is an aromatic or an alkyl substituted aromatic having from 6 to 15 carbon atoms, wherein said equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate is from about 5.0 to about 10.0, wherein the equivalent ratio of said free NCO groups to said OH groups and said NH groups of said curative is from about 1.35 to about 1.6, and wherein said polyol curative is alkyl diol having from 2 to 12 carbon atoms, a polyhydric alcohol having from 3 to 15 carbon atoms and from 3 to 8 hydroxyl groups, a carbohydrate having from 5 to 12 carbon atoms and from 4 to 10 hydroxyl groups, or combinations thereof. 
     
     
       20. A process according to claim  19   34 , wherein said first and second treatment free substrates are a fiberglass reinforced plastic. 
     
     
       21. A urethane adhesive capable of bonding to a treatment-free surface of plastic, fiber reinforced plastic, or metal comprising: 
       a urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being at least 2.0 so that said prepolymer component has free NCO groups, and  
       a curative component comprising a nitrogen-free polyol curative having hydroxy groups and a primary polyamine,  
       the equivalent ratio of said free NCO groups of said prepolymer to said hydroxy groups and amine groups of said curative component is from about 1.2 to about 2.0.  
     
     
       22. A two component urethane adhesive according to claim  1 , wherein said equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate is from  2  to  20 . 
     
     
       23. A two component urethane adhesive according to claim  1 , wherein the equivalent ratio of said free NCO groups to said hydroxy groups and said amine groups of said curative component is  1 . 25  to  1 . 50 . 
     
     
       24. A urethane adhesive according to claim  21 , wherein said equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate is from 2 to 20. 
     
     
       25. A urethane adhesive according to claim  21 , wherein the equivalent ratio of said free NCO groups to said hydroxy groups and said amine groups of said curative component is  1 . 25  to  1 . 50 . 
     
     
       26. A two component urethane adhesive comprising: 
         a urethane prepolymer component and a curative component, said urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to the hydroxyl terminated intermediate being at least  2 . 0  so that said prepolymer component has free NCO groups, said curative component comprising a nitrogen - free polyol curative which comprises a nitrogen - free polyether polyol having OH groups, a nitrogen - free polyester polyol having OH groups, a nitrogen - free low molecular weight polyol, or combinations thereof and a primary polyamine, the amount of said curative being such that the equivalent ratio of said free NCO groups to said hydroxy groups and amine groups of said curative component is from about  1 . 2  to about  2 . 0 , the two component urethane adhesive being capable of bonding to a surface treatment - free plastic, fiber reinforced plastic, or metal, wherein the urethane prepolymer component does not contain an aliphatic isocyanate.   
     
     
       27. A urethane adhesive composite containing treatment- free substrates therein, comprising:    
       
         the urethane adhesive, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component, said urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being from about  2  to  20  so that said prepolymer component contains free NCO groups,  
       
         said urethane curative component containing a nitrogen - free polyol curative having hydroxy groups therein and a primary polyamine containing amine groups therein, the equivalent ratio of said free NCO groups to said hydroxy groups and amine groups of said curative component being about  1 . 2  to about  2 ,    
         at least two surface treatment - free substrates, said substrates bonded together by said urethane adhesive,    
       
         wherein the urethane prepolymer component does not contain an aliphatic isocyanate. 
       
     
     
       28. A process for adhering at least one treatment- free substrate to another substrate, comprising the steps of:    
         applying a two component urethane adhesive to at least a first treatment - free substrate, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component, said urethane prepolymer component being made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being from about  2  to  20  so that said prepolymer component contains free NCO groups,    
         said urethane curative component containing a nitrogen - free polyol curative having hydroxy groups therein and a primary polyamine containing amine groups therein, the equivalent ratio of said free NCO groups to said hydroxy groups and said amine groups of said curative component being about  1 . 2  to about  2 ,    
       
         applying said two component urethane adhesive to at least a second substrate, and curing said two component urethane adhesive by heating,  
       
       
         wherein the urethane prepolymer component does not contain an aliphatic isocyanate. 
       
     
     
       29. A urethane adhesive capable of bonding to a treatment- free surface of plastic, fiber reinforced plastic, or metal comprising:    
       
         a urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being at least  2 . 0  so that said prepolymer component has free NCO groups, and  
       
         a curative component comprising a nitrogen - free polyol curative having hydroxy groups and a primary polyamine,    
       
         the equivalent ratio of said free NCO groups of said prepolymer to said hydroxy groups and amine groups of said curative component is from about  1 . 2  to about  2 . 0 ,  
       
       
         wherein the urethane prepolymer component does not contain an aliphatic isocyanate. 
       
     
     
       30. A urethane adhesive composite containing treatment- free substrates therein, comprising:    
       
         the urethane adhesive, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component, said urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being from about  5  to  10  so that said prepolymer component contains free NCO groups,  
       
         said urethane curative component containing a nitrogen - free polyol curative having hydroxy groups therein and a primary polyamine containing amine groups therein, the equivalent ratio of said free NCO groups to said hydroxy groups and amine groups of said curative component is from about  1 . 35  to about  1 . 6 ,    
       at least two surface treatment- free substrates, said substrates bonded together by said urethane adhesive; and    
       
         wherein said hydroxyl terminated intermediate is a polyester polyol or a polyether polyol having a number average molecular weight of from about  400  to about  10 , 000 , wherein said polyisocyanate has the formula R(NCO) 
         n  
         here n is an integer of  2 ,  3  or  4 , or combinations of said polyisocyanate; and  
       
         wherein each of said substrates is a treatment - free fiber - glass reinforced plastic, a treatment - free metal, or a treatment - free plastic substrate;    
       
         wherein said polyether polyol is made from an alkylene oxide having from  2  to  10  carbon atoms, wherein said polyester polyol is made from a polyhydric alcohol having from  2  to  15  carbon atoms and a polycarboxylic acid having from  2  to  14  carbon atoms, wherein R of said polyisocyanate is an aromatic or an alkyl substituted aromatic having from  6  to  15  carbon atoms, and wherein said polyol curative is alkyl diol having from  2  to  12  carbon atoms, a polyhydric alcohol having from  3  to  15  carbon atoms and from  3  to  8  hydroxyl groups, a carbohydrate having from  5  to  12  carbon atoms and from  4  to  10  hydroxyl groups, or combinations thereof. 
       
     
     
       31. A urethane adhesive composite according to claim  30 , wherein said polyether polyol and said polyester polyol has a number average molecular weight of from about  2 , 000  to about  4 , 000 , 
       
         wherein said hydroxyl terminated intermediate is polypropylene either diol, polybutylene either diol, polytetramethylene ether, polycaprolactone diol, or combinations thereof, wherein said equivalent ratio of said free NCO groups to said hydroxyl groups and said amine groups of said curative component is from about  1 . 35  to about  1 . 45 , wherein said polyisocyanate is methylene diphenyl diisocyanate or toluene diisocyanate, and wherein said polyol curative is an ethylene or propylene oxide adduct of trimethylol propane, pentaerythritol, glycerol, an alkyl glucoside wherein said alkyl has from  1  to  12  carbon atoms, or combinations thereof. 
       
     
     
       32. A urethane adhesive composite according to claim  31  including a filler in said urethane prepolymer component, the amount of said filler being from about  5  parts to about  100  parts by weight for every  100  parts by weight of said prepolymer component, and including a filler in said curative component, the amount of said filler being from about  5  parts to about  100  parts by weight for every  100  parts by weight of said polyol curative. 
     
     
       33. A urethane adhesive composite containing treatment- free substrates therein, comprising:    
       
         the urethane adhesive, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component, said urethane prepolymer component made from a hydroxyl terminated intermediate and a polyisocyanate, the equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate being from about  2  to  20  so that said prepolymer component contains free NCO groups,  
       
         said urethane curative component containing a nitrogen - free polyol curative having hydroxy groups therein and a primary polyamine containing amine groups therein,    
       
         wherein the equivalent ratio of said free NCO groups to said hydroxy groups and said amine groups of said curative component is  1 . 25  to  1 . 50 ,  
       
         at least two surface treatment - free substrates, said substrates bonded together by said urethane adhesive.   
     
     
       34. A process for adhering at least one treatment- free substrate to another substrate, comprising the steps of:    
         applying a two component urethane adhesive to at least a first treatment - free substrate, said urethane adhesive being the reaction product of a two component system of a urethane prepolymer component and a urethane curative component said urethane prepolymer component being made from a hydroxyl terminated intermediate and a polyisocyanate,    
       
         wherein said hydroxyl terminated intermediate is a polyester polyol or a polyether polyol having a number average molecular weight of from about  400  to about  10 , 000 , wherein said polyisocyanate has the formula R(NCO) 
         n  
         wherein n is an integer of  2 ,  3  or  4 , wherein R is an aromatic or an alkyl substituted aromatic having from  6  to  15  carbon atoms, or combinations of said polyisocyanate, and  
       
       
         wherein said polyether polyol is made from an alkylene oxide having from  2  to  10  carbon atoms, wherein said polyester polyol is made from a polyhydric alcohol having form  2  to  15  carbon atoms and a polycarboxylic acid having from  2  to  14  carbon atoms, wherein said equivalent ratio of said polyisocyanate to said hydroxyl terminated intermediate is from about  5 . 0  to about  10 . 0 , so that said prepolymer component contains free NCO groups,  
       
       
         said urethane curative component containing a nitrogen free polyol curative having hydroxy groups therein and a primary polyamine containing amine groups therein, and  
       
       
         wherein the equivalent ratio of said free NCO groups to said hydroxy groups and said amine groups of said curative component is from about  1 . 35  to about  1 . 6 , and wherein said polyol curative is alkyl diol having from  2  to  12  carbon atoms, a polyhydric alcohol having from  3  to  15  carbon atoms and from  3  to  8  hydroxyl groups, a carbohydrate having from  5  to  12  carbon atoms and from  4  to  10  hydroxyl groups, or combinations thereof, and  
       
       
         applying said two component urethane adhesive to at least a second substrate, and curing said two component urethane adhesive by heating to a temperature above  50 ° C.,  
       
         and wherein each said first and second substrate is individually a treatment - free fiberglass reinforced plastic, a treatment - free metal, or a treatment - free plastic substrate.