Polyurethane adhesive for windshield applications

Abstract

A polyurethane adhesive which is useful in bonding porous and non-porous surfaces is provided. The adhesive is especially useful in bonding windshield glass into automotive frames under a variety of environmental conditions, particularly in after market windshield replacement applications. The polyurethane includes at least one urethane prepolymer which is based on at least one thermoplastic polyol. In one embodiment, the urethane prepolymer may be formed from one or more polyisocyanates, one or more polyetherpolyols and one or more thermoplastic polyesterpolyols, wherein the prepolymer has a free isocyanate content of from about 0.6 to about 3.5% by weight, based on the weight of the polyurethane. In another embodiment, a one-part adhesive composition is provided which includes an isocyanate-functional and thermoplastic polyurethane prepolymer having a free isocyanate content of from about 0.6 to about 3.5% by weight, based on the weight of the polyurethane, and a combination of several catalysts which are capable of catalyzing the reaction of isocyanate moieties with isocyanate-reactive moieties while providing less temperature dependent catalyzing of the reaction between isocyanate moieties and water. Also provided is a process for bonding two or more substrates together utilizing the polyurethane adhesive. In automotive windshield replacement applications, the polyurethane adhesive allows for a sufficient working time and development of green strength to provide a safe drive-away time within 1 hour at a temperature from about 0 to about 100° C.

1 - 86 . (canceled)  
   
   
       87 . An automotive windshield replacement method which comprises: 
 a) applying an adhesive to an automotive windshield and/or an automobile body substrate, said adhesive comprising at least one urethane prepolymer formed from reaction materials comprising: 
 i) isophorone diisocyanate and/or 4,4′-diphenylmethanediisocyanate:  
 ii) an ethylene oxide-end-capped triol having a weight average molecular weight of about 4500 to about 5000; and  
 iii) hexanediol adipate  
   b) contacting the substrates together, within the working time of the adhesive, along at least a portion of the substrate(s) to which the adhesive has been applied; and    c) allowing the adhesive to bond the substrates together.    
   
   
       88 . An automotive windshield replacement method according to  claim 87 , wherein said reaction materials further comprise at least one of a polypropylene glycol and a propylene oxide-end-capped triol.  
   
   
       89 . An automotive windshield replacement method according to  claim 88 , wherein said reaction materials comprise a polypropylene glycol having a weight average molecular weight of about 3500 to about 4500.  
   
   
       90 . An automotive windshield replacement method according to  claim 87 , wherein the adhesive (1) has a tensile strength of 1.0 MPa or greater when measured at a strain rate of 1 meter/second, (2) has a compression force of less than about 0.18 MPa when measured at 5° C., (3) provides a safe drive-away time according to U.S. Federal Motor Vehicle Safety Standards of one hour or less from application of the adhesive to the windshield and/or automobile body, and (4) provides a working time of about 6 to about 15 minutes.  
   
   
       91 . An automotive windshield replacement method which comprises: 
 a) applying an adhesive to an automotive windshield and/or an automobile body substrate, said adhesive comprising at least two urethane prepolymers, the first said prepolymer formed from reaction materials comprising: 
 i) isophorone diisocyanate and/or 4,4′-diphenylmethanediisocyanate, and  
 ii) an ethylene oxide-end-capped triol having a weight average molecular weight of about 4500 to about 5000; and  
   the second said prepolymer formed from reaction materials comprising: 
 i) isophorone diisocyanate and/or 4,4′-diphenylmethanediisocyanate, and  
 ii) a thermoplastic polyesterpolyol;  
   b) contacting the substrates together, within the working time of the adhesive, along at least a portion of the substrate(s) to which the adhesive has been applied; and    c) allowing the adhesive to bond the substrates together.    
   
   
       92 . An automotive windshield replacement method according to  claim 90  wherein the reaction materials of said second prepolymer comprise hexanediol adipate.  
   
   
       93 . An automotive windshield replacement method according to  claim 92  wherein the reaction materials of said first prepolymer further comprise at least one of a polypropylene glycol and a propylene oxide-end-capped triol.  
   
   
       94 . An automotive windshield replacement method according to  claim 93 , wherein said reaction materials of said first prepolymer comprise a polypropylene glycol having a weight average molecular weight of about 3500 to about 4500 comprise hexanediol adipate.  
   
   
       95 . An automotive windshield replacement method according to  claim 93 , wherein said reaction materials of said first prepolymer comprise a propylene oxide-end-capped triol.  
   
   
       96 . An automotive windshield replacement method according to  claim 91  wherein the reaction materials of said first prepolymer further comprise at least one of a polypropylene glycol and a propylene oxide-end-capped triol.  
   
   
       97 . An automotive windshield replacement method according to  claim 96 , wherein said reaction materials of said first prepolymer comprise a polypropylene glycol having a weight average molecular weight of about 3500 to about 4500.comprise hexanediol adipate.  
   
   
       98 . An automotive windshield replacement method according to  claim 96 , wherein said reaction materials of said first prepolymer comprise a propylene oxide-end-capped triol.  
   
   
       99 . An automotive windshield replacement method according to  claim 91 , wherein the adhesive (1) has a tensile strength of 1.0 MPa or greater when measured at a strain rate of 1 meter/second, (2) has a compression force of less than about 0.18 MPa when measured at 5° C., (3) provides a safe drive-away time according to U.S. Federal Motor Vehicle Safety Standards of one hour or less from application of the adhesive to the windshield and/or automobile body, and (4) provides a working time of about 6 to about 15 minutes.