One-part solvent-based adhesive for bonding polymer materials

Abstract

What is disclosed are adhesives and bonding methods employing a single coat of a solvent-based adhesive that effectively bonds thermoplastic polymers and especially thermoplastic elastomers. The adhesive components are a organosilane component selected from organosilane-isocyanate adduct and isocyanato-organosilane, a post-chlorinated polymer containing propylene repeating units or derivative thereof, and solvent. Also disclosed are methods for joining a rigid, structural substrate to a molten polymer such as a TPE via injection molding or extrusion. Durable adhesion between the adhesive treated portion of the rigid sub-strate and the melt-processed polymer is achieved with or without a previous heat treatment on the adhesive-coated substrate prior to joining to the thermoplastic melt.

1 . A liquid adhesive comprising an organosilane-containing component selected from the group consisting of a organosilane-isocyanate adduct and an isocyanato-organosilane, a polymer comprising post-chlorinated propylene repeating units, and an organic solvent.  
   
   
       2 . The adhesive according to  claim 1  wherein said polymer has a weight average molecular weight of from 5,000 to 60,000 and a chlorine content of from 10 wt. % to 60 wt. %.  
   
   
       3 . The adhesive according to  claim 1  wherein said polymer is selected from crystalline polypropylene, noncrystalline polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and propylene-C 4 -C 10 -α-olefin copolymer.  
   
   
       4 . The adhesive according to  claim 1  wherein said post-chlorinated polymer is maleated.  
   
   
       5 . The adhesive according to  claim 1  wherein said organic solvent is selected from the group consisting of aromatic and halogenated aromatic hydrocarbons.  
   
   
       6 . The adhesive according to  claim 1  having a total solids content of from 5 to 50 wt. %.  
   
   
       7 . The adhesive according to  claim 1  wherein said organosilane-containing component is a organosilane-isocyanate adduct containing the linkage —NH—C(O)-A-R—Si, wherein A is O, S, or N, and R is a divalent C 1 -C 20  hydrocarbyl group.  
   
   
       8 . The adhesive according to  claim 1  wherein the organosilane-containing component is an isocyanatosilane containing at least one hydrolyzable group and at one free isocyanate group and having the structure (E)  
     
       
         
         
             
             
         
       
     
     wherein R 1  is a monovalent aliphatic, cycloaliphatic or aromatic radical having from 1 to 20 carbon atoms; R 2  is a monovalent aliphatic, cycloaliphatic or aromatic organic radical containing from 1 to 8 carbon atoms, —R 3 —O—R 4 , and  
     
       
         
         
             
             
         
       
     
     where R 3  is an alkylene group having from 1 to 4 carbon atoms and R 4  is an alkyl group having from 1 to 4 carbon atoms; a is zero or 1, and Z is a divalent organic radical attached to the silicon atom via a carbon-silicon bond.  
   
   
       9 . A method for joining a polymer extrudate to a continuous or elongated structural member which has been treated with the adhesive of  claim 1  comprising passing the adhesive-treated substrate adjacent to or through an extruder die, and joining the member to the extrudate to form a joined article, and cooling the joined article.  
   
   
       10 . The method of  claim 9  wherein said joined article is a window channel.  
   
   
       11 . A method for joining an injection molded polymer to a structural member which has been treated with the adhesive of  claim 1 , comprising inserting the adhesive-treated member into an injection mold cavity adapted to receive the member, exposing an adhesive-treated surface of the member to the mold cavity, injecting said polymer into the cavity contacting the polymer with the treated surface of the member, and cooling the polymer.