CAST URETHANES MADE FROM LOW FREE MONOMER PREPOLYMER WITH POLYCARBONATE BACKBONE
Polycarbonate based polyurethane prepolymers having a low amount of free isocyanate monomer with excellent handling and processing properties are prepared and used in the preparation of cast polyurethane polymers with excellent performance and handling properties.
1 . An isocyanate terminated, polycarbonate based polyurethane prepolymer, obtained by the reaction of one or more polyisocyanate monomer with a polyol component comprising one or more polyol, wherein at least one polyol is a polycarbonate polyol comprising a repeating unit of formula I or a co-polycarbonate polyol comprising more than one repeating unit of formula I
wherein X is selected from the group consisting of C 2-12 alkyl groups, wherein the prepolymer has a free poly isocyanate monomer content of less than 1 wt %, based on the weight of the prepolymer.
2 . The prepolymer according to claim 1 having a free polyisocyanate monomer content of less than 0.1 wt %, based on the weight of the prepolymer.
3 . The prepolymer according to claim 1 , wherein the one or more polyols comprises one or more co-polycarbonate polyols comprising a repeating unit of formula A and one or more repeating units of formula B
wherein R is C 2-12 alkyl other than straight chain C 6 H 12 , in a molar ratio of A to all repeating units of formula B of from 9:1 to 1:9.
4 . The prepolymer according to claim 3 wherein at least 50% of the one or more repeating units of formula B in at least one of the one or more co-polycarbonate polyols is of formula B 5
5 . The prepolymer according to claim 4 wherein 60 to 100% of all repeating units in at least one of the one or more co-polycarbonate polyols are of formula A and B 5 .
6 . The prepolymer according to claim 5 having a free polyisocyanate monomer content of less than 0.1 wt %, based on the weight of the prepolymer.
7 . The prepolymer according to claim 1 wherein at least one polyol is a polycarbonate polyol comprising a repeating unit of formula I or a co-polycarbonate polyol comprising more than one repeating units of formula I
wherein X is selected from the group consisting of C 5-6 alkyl groups.
8 . The prepolymer according to claim 7 having a free polyisocyanate monomer content of less than 0.1 wt %, based on the weight of the prepolymer.
9 . The prepolymer according to claim 1 wherein the one or more polyisocyanate monomer comprises paraphenylene diisocyanate, toluidine diisocyanate, isophorone diisocyanate, 2,4- and/or 4,4′-methylene bis (phenylisocyanate), toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, naphthalene-1,5-diisocyanate, diphenyl-4,4′-diisocyanate, dibenzyl-4,4′-diisocyanate, stilbene-4,4′-diisocyanate, benzophenone-4,4′diisocyanate, 1,3- and 1,4-xylene diisocyanates, 1,6-hexamethylene diisocyanate, 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate, and or geometric isomers of 1,1′-methylene-bis(4-isocyanatocyclohexane).
10 . The prepolymer according to claim 8 wherein the one or more polyisocyanate monomer comprises paraphenylene diisocyanate, 4,4′-methylene bis (phenylisocyanate), toluene-2,4-diisocyanate, toluene-2,6-diisocyanate and/or 1,6-hexamethylene diisocyanate.
11 . The prepolymer according to claim 2 wherein the one or more polyisocyanate monomer comprises paraphenylene diisocyanate, toluidine diisocyanate, isophorone diisocyanate, 2,4- and/or 4,4′-methylene bis (phenylisocyanate), toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, naphthalene-1,5-diisocyanate, diphenyl-4,4′-diisocyanate, dibenzyl-4,4′-diisocyanate, stilbene-4,4′-diisocyanate, benzophenone-4,4′diisocyanate, 1,3- and 1,4-xylene diisocyanates, 1,6-hexamethylene diisocyanate, 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate, and or geometric isomers of 1,1′-methylene-bis(4-isocyanatocyclohexane).
12 . The prepolymer according to claim 1 obtained by a process comprising reacting one or more polyisocyanate monomer with a polyol component comprising one or more polyols wherein at least one polyol is a polycarbonate polyol comprising a repeating unit of formula I or a co-polycarbonate polyol comprising more than one repeating units of formula I
wherein X is selected from the group consisting of C 2-12 alkyl groups, followed by removing unreacted polyisocyanate monomer by distillation under reduced pressure optionally in the presence of one or more inert solvents having a boiling point of 120° C. or higher selected from hydrocarbons, esters, diesters, lactones carbonates and amides.
13 . The prepolymer according to claim 2 obtained by a process comprising reacting one or more polyisocyanate monomer with a polyol component comprising one or more polyols wherein at least one polyol is a polycarbonate polyol comprising a repeating unit of formula I or a co-polycarbonate polyol comprising more than one repeating units of formula I
wherein X is selected from the group consisting of C 2-12 alkyl groups, followed by removing unreacted polyisocyanate monomer by distillation under reduced pressure optionally in the presence of one or more inert solvents having a boiling point of 120° C. or higher selected from hydrocarbons, esters, diesters, lactones carbonates and amides.
14 . A process for preparing a prepolymer comprising reacting one or more polyisocyanate monomer with a polyol component comprising one or more polyols wherein at least one polyol is a polycarbonate polyol comprising a repeating unit of formula I or a co-polycarbonate polyol comprising more than one repeating units of formula I
wherein X is selected from the group consisting of C 2-12 alkyl groups, followed by removing unreacted polyisocyanate monomer by distillation under reduced pressure to produce a prepolymer having a free polyisocyanate monomer content of less than 1 wt %, based on the weight of the prepolymer.
15 . The process according to claim 14 wherein the prepolymer has a free polyisocyanate monomer content of less than 0.1 wt %, based on the weight of the prepolymer.
16 . The process according to claim 14 wherein unreacted polyisocyanate monomer is removed by distillation under reduced pressure in the presence of one or more inert solvents having a boiling point of 120° C. or higher selected from hydrocarbons, esters, diesters, lactones carbonates and amides.
17 . The process according to claim 15 wherein unreacted polyisocyanate monomer is removed by distillation under reduced pressure in the presence of one or more inert solvents having a boiling point of 120° C. or higher selected from hydrocarbons, esters, diesters, lactones carbonates and amides.
18 . A polyurethane curing composition comprising a prepolymer according to claim 1 and a curing agent comprising one or more polyol, polyamine, polyamine derivative or a combination thereof.
19 . A polyurethane elastomer prepared by curing the polyurethane curing composition according to claim 18 .