Polyurethane

Abstract

A self-healing polyurethane, a polyol for use in the polyurethane, and the use of the polyol and/or polyurethane in coatings, elastomers, composites, adhesives and/or sealants is described, where the polyurethane is capable of exhibiting self-healing which results in recovery of a proportion of one or more physical parameters. The self-healing polyurethane is the reaction product of reactants comprising a polyol, a polyisocyanate; and optionally, a chain extender, where the polyol comprises at least one dimer fatty residue; at least one carbonate group; and at least two hydroxyl end groups.

1 . A polyurethane which is capable of self-healing and which is the reaction product of reactants comprising:
 (A) a polyol, wherein the polyol comprises:
 (i) at least one dimer fatty residue; 
 (ii) at least one carbonate group; and 
 (iii) at least two hydroxyl end groups; 
   (B) a polyisocyanate; and   (C) optionally, a chain extender.   
     
     
         2 . A polyurethane obtained by reacting:
 (A) a polyol which is the reaction product of reactants comprising:
 (i) at least one of a dimer fatty diacid, a dimer fatty diol, a dimer fatty diamine, or a dimer fatty diisocyanate; 
 (ii) a diaryl carbonate, a dialkyl carbonate or phosgene; and 
 (iii) optionally, a non-dimeric diol, a non-dimeric diacid and/or a lactone, 
   wherein the polyol is capable of forming at least two hydrogen bonds within the polyurethane;   (B) a polyisocyanate; and   (C) optionally, a chain extender,   wherein the polyurethane is capable of self-healing.   
     
     
         3 . A polyurethane according to  claim 1  wherein the polyol comprises a polyisocyanate reactant which is not an aromatic polyisocyanate. 
     
     
         4 . A polyurethane according to  claim 1  wherein the polyol comprises a dimer fatty diol reactant. 
     
     
         5 . A polyurethane according to  claim 1  wherein the polyol is capable of forming at least 3 hydrogen bonds within the polyurethane. 
     
     
         6 . A polyurethane according to  claim 1  wherein:
 (B) the polyisocyanate comprises an aromatic polyisocyanate. 
 
     
     
         7 . A polyurethane according to  claim 1  which comprises a chain extender wherein the chain extender is a branched diol or diamine. 
     
     
         8 . A polyurethane according to  claim 1  wherein the polyurethane has at least 30% self-healing recovery of a physical parameter when the polyurethane is exposed to a temperature of at least 20° C. for a time of at least 24 hours. 
     
     
         9 . A polyurethane according to  claim 6  wherein the physical parameter is selected from tensile strength, elongation and/or scratch length. 
     
     
         10 . A polyurethane according to  claim 1  wherein the polyurethane has at least 30% self-healing recovery of a physical parameter after a first cut and a second cut, wherein the first cut is made and self-healed and the second cut is made at the location of the first cut after it has self-healed. 
     
     
         11 . A coating composition comprising a polyurethane according to  claim 1 . 
     
     
         12 . An article comprising:
 a substrate; and   a coating composition according to  claim 11 .   
     
     
         13 . An adhesive, sealant, elastomer or composite composition comprising a polyurethane according to  claim 1 . 
     
     
         14 . An article comprising:
 a substrate; and   an adhesive composition according to  claim 13 .   
     
     
         15 . A polyol for a polyurethane according to  claim 1 , wherein the polyol is the reaction product of reactants comprising:
 (i) at least one of a dimer fatty diacid, a dimer fatty diol, a dimer fatty diamine, or a dimer fatty diisocyanate;   (ii) at least one of a diaryl carbonate, a dialkyl carbonate or phosgene;   (iii) optionally, a non-dimeric diol;   (iv) optionally, a non-dimeric diacid; and   (v) optionally, a lactone,   
       wherein the polyol comprises at least two hydroxyl end groups and comprises at least two internal groups which are capable of hydrogen bonding. 
     
     
         16 . A polyol according to  claim 15  wherein (i) is present at 10 to 80 wt % based on the total weight of the polyol. 
     
     
         17 . A polyol according to  claim 16  wherein (ii) is present at 2 to 20 wt % based on the total weight of the polyol. 
     
     
         18 . The method of providing or improving a self-healing ability of a polyurethane comprising forming the polyurethane from a reaction mixture comprising a polyol comprising at least one of a dimer fatty diacid, dimer fatty diol, dimer fatty diamine or dimer fatty diisocyanate,
 wherein the polyol also comprises at least one carbonate group.