Laminating Adhesives Based on Primary Hydroxyl-Containing Curatives

Abstract

A curative containing two or more primary hydroxyl groups per molecule and one or more moieties derived from a secondary hydroxyl-containing polyol such as polypropylene glycol is prepared in a multistage process wherein the secondary hydroxyl-containing polyol is end-capped with an excess of a reactant such as a polybasic acid and the resulting functionalized intermediate is then reacted with a polyol such as glycerin or diethylene glycol containing primary hydroxyl groups. Such curatives may be used in combination with isocyanate-functionalized polyurethane prepolymers to provide two component adhesives useful for laminating thin films and/or foils.

1 - 20 . (canceled) 
   
   
       21 . A laminating adhesive, comprising Component A and Component B, wherein Component A comprises at least one isocyanate-functionalized compound and Component B comprises a curative containing a molecule having at least about two primary hydroxyl groups and at least about two secondary hydroxyl groups, the Component A and Component B being reactive when mixed to form a cured adhesive. 
   
   
       22 . The laminating adhesive of  claim 21 , wherein Component B has the structure:
   Y—O—C(═O)—Z—C(═O)—O—CH(CH 3 )—CH 2 —O—(C 3 H 6 O) n —CH 2 —CH(CH 3 )—O—C(═O)—Z′—C(═O)—O—Y′,   wherein Y and Y′ are the same or different and are selected from the group consisting of HO—CH 2 —CH(OH)—CH 2 — and HO—(CH 2 —CH 2 —O—) p —CH 2 —CH 2 —,   Z and Z′ are the same or different and are selected from the group consisting of —C 6 H 4 —, —(CH 2 ) o — and combinations thereof,   p is 0 or an integer of 1 to 3,   o is an integer of from 2 to 10, and   n is 0 or an integer of from 1 to 100.   
   
   
       23 . The laminating adhesive of  claim 21 , wherein Component B has the structure:
   Y—O—C(═O)—Z—C(═O)—O—CH(CH 3 )—CH 2 —O—(C 3 H 6 O) n —CH 2 —CH(CH 3 )—O—C(═O)—Z′—C(═O)—O—Y′,   wherein Y and Y′ are the same or different and are selected from the group consisting of HO—CH 2 —CH(OH)—CH 2 — and HO—(CH 2 —CH 2 —O—) p —CH 2 —CH 2 —,   Z and Z′ are the same or different and are selected from the group consisting of —C 6 H 4 —, —(CH 2 )— and combinations thereof,   p is 0 or an integer of 1 to 3,   o is an integer of from 2 to 10, and   n is an integer of from 4 to 50.   
   
   
       24 . A process for making curative Component B of  claim 21 , comprising:
 reacting a first polyol containing at least one secondary hydroxyl group with a stoichiometric excess of a reactant selected from the group consisting of polybasic acids, polybasic acid anhydrides, polybasic acid esters, and polyisocyanates to form an intermediate containing at least about two terminal functional groups per molecule, each functional group independently selected from the group consisting of isocyanate, carboxylic acid and carboxylic acid ester;   reacting the intermediate with a stoichiometric excess of a second polyol containing at least 2 primary hydroxyl groups to convert terminal functional groups on the intermediate to urethane or ester groups and form the curative component.   
   
   
       25 . The process of  claim 24  wherein the first polyol is a polyalkylene glycol containing secondary hydroxyl groups. 
   
   
       26 . The process of  claim 24  wherein the first polyol is a polypropylene glycol. 
   
   
       27 . The process of  claim 24  wherein the first polyol has a number average molecular weight of from about 200 to about 10,000 grams per mole. 
   
   
       28 . The process of  claim 24  wherein the reactant is selected from the group consisting of aliphatic linear saturated dicarboxylic acids containing from 4 to 12 carbon atoms, phthalic acids, orthophthalic acid anhydride, and mixtures thereof. 
   
   
       29 . The process of  claim 24  wherein the second polyol is an aliphatic compound containing 2 to 5 hydroxyl groups per molecule and the ratio of primary hydroxyl groups to secondary hydroxyl groups in the second polyol is at least 2:1. 
   
   
       30 . The process of  claim 24  wherein the second polyol is selected from the group consisting of ethylene glycol, ethylene glycol oligomers, 1,4 butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol and mixtures thereof. 
   
   
       31 . The process of  claim 24  wherein reactant is selected from the group consisting of adipic acid, orthophthalic acid anhydride and mixtures thereof. 
   
   
       32 . The process of  claim 24  wherein the curative component comprises a molecule having 2 primary hydroxyl groups and 2 secondary hydroxyl groups. 
   
   
       33 . The process of  claim 24  wherein the curative component has the structure:
   Y—O—C(═O)—Z—C(═O)—O—CH(CH 3 )—CH 2 —O—(C 3 H 6 O) n —CH 2 —CH(CH 3 )—O—C(═O)—Z′—C(═O)—O—Y′,   wherein Y and Y′ are the same or different and are selected from the group consisting of HO—CH 2 —CH(OH)—CH 2 — and HO—(CH 2 —CH 2 —O—) p —CH 2 —CH 2 —, Z and Z′ are the same or different and are selected from the group consisting of —C 6 H 4 —, —(CH 2 ) o — and combinations thereof, p is 0 or an integer of 1 to 3, o is an integer of from 2 to 10, and n is  0  or an integer of from 1 to 100.   
   
   
       34 . The process of  claim 24  wherein the curative component has the structure:
   Y—O—C(═O)—Z—C(═O)—O—CH(CH 3 )—CH 2 —O—(C 3 H 6 O) n —CH 2 —CH(CH 3 )—O—C(═O)—Z′—C(═O)—O—Y′,   wherein Y and Y′ are the same or different and are selected from the group consisting of HO—CH 2 —CH(OH)—CH 2 — and HO—(CH 2 —CH 2 —O—)p-CH 2 —CH 2 —, Z and Z′ are the same or different and are selected from the group consisting of —C 6 H 4 —, —(CH 2 ) o — and combinations thereof, p is 0 or an integer of 1 to 3, o is an integer of from  2  to  10 , and n is an integer of from 4 to 50.   
   
   
       35 . A laminate comprised of at least one polymeric film and cured reaction products of the two component reactive adhesive of  claim 21 . 
   
   
       36 . The laminate of  claim 35  comprised of at least two polymeric films, wherein the two component reactive adhesive is located between two of said polymeric films and adheres said polymeric films to each other. 
   
   
       37 . The laminate of  claim 35  wherein at least one polymeric film is comprised of a thermoplastic selected from the group consisting of polyethylene terephthalate, polyethylene, polypropylene, and polyvinylidene chloride. 
   
   
       38 . The laminate of  claim 35  additionally comprising a metal foil, wherein the two component reactive adhesive is located between the metal foil and at least one polymeric film. 
   
   
       39 . The laminate of  claim 35  wherein at least one polymeric film is metallized or has a coating comprised of an inorganic oxide deposited thereon. 
   
   
       40 . The laminate of  claim 35  comprising (a) a first layer comprised of a first polyolefin or first polyester; (b) a second layer comprised of a second polyolefin, which may be the same or different from the first polyolefin; a second polyester, which may be the same as or different from the first polyester; or a metal foil; (c) and cured reaction products of the two component reactive adhesive of claim  1  bonding the first layer to the second layer.