BIODEGRADABLE POLYURETHANES
A method for preparing biodegradable polyurethanes includes contacting a flowable quasi-pre-polymer including free aliphatic polyisocyanate compounds with a polyester polyol hardener having a functionality of at least two to form a reactive liquid mixture. The quasi-prepolymer can, for example, be formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound to form an adduct of the polyisocyanate component and the polyol component wherein a sufficient excess of the polyisocyanate component is used to form the quasi-prepolymer.
1 . A method for preparing biodegradable polyurethanes comprising:
contacting a flowable quasi-prepolymer comprising free aliphatic polyisocyanate compounds with a polyester polyol hardener having a functionality of at least two to form a reactive liquid mixture.
2 . The method of claim 1 wherein the quasi-prepolymer is formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound to form an adduct of the polyisocyanate component and the polyol component wherein a sufficient excess of the polyisocyanate component is used to form the quasi-prepolymer.
3 . The method of claim 2 wherein the polyisocyanate component is contacted with the polyol component in the presence of a catalyst.
4 . The method of claim 3 wherein the catalyst is a tertiary amine or an organobismuth compound.
5 . The method of claim 1 wherein the quasi-prepolymer is formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound, wherein the molar ratio of aliphatic polyisocyanate compounds to polyol compounds is at least 2:1 and subsequently adding aliphatic polyisocyanate compound.
6 . The method of claim 1 wherein the quasi-prepolymer is formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound, wherein the molar ratio of aliphatic polyisocyanate compounds to polyol compounds is greater than 2:1.
7 . The method of claim 1 wherein the quasi-prepolymer is formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound, wherein the molar ratio of aliphatic polyisocyanate compounds to polyol compounds is greater than 3:1.
8 . The method of claim 1 wherein the quasi-prepolymer is formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound, wherein the molar ratio of aliphatic polyisocyanate compounds to polyol compounds is greater than 4:1.
9 . The method of claim 6 wherein the polyisocyanate component is contacted with the polyol component in the presence of a catalyst.
10 . The method of claim 9 wherein the catalyst is a tertiary amine or an organobismuth compound.
11 . The method of claim 9 wherein the catalyst is an organobismuth compound.
12 . The method of claim 1 wherein the polyester polyol has a functionality greater than 2.0.
13 . The method of claim 1 wherein the polyester polyol has a functionality is at least 2.5.
14 . The method of claim 12 wherein the polyester polyol comprises hydroxyl-terminated compounds having hydrolysable ester linkages:
15 . The method of claim 14 wherein the polyester polyol comprises a polyalkylene glycol ester or a polyester prepared from at least one cyclic ester.
16 . The method of claim 15 wherein the polyester polyol comprises poly(ethylene adipate), poly(ethylene glutarate), poly(ethylene azelate), poly(trimethylene glutarate), poly(pentamethylene glutarate), poly(diethylene glutarate), poly(diethylene adipate), poly(triethylene adipate), poly(1,2-propylene adipate), a mixture thereof, or a copolymer of at least two thereof.
17 . The method of claim 15 wherein the polyester polyol comprises polyesters prepared from at least one of ε-caprolactone, glycolide or DL-lactide.
18 . The method of claim 15 wherein the polyester polyol comprises polyesters prepared from castor-oil.
19 . The method of claim 1 wherein the polyisocyanate compounds comprise at least one of lysine diisocyanate, an alkyl ester of lysine diisocyanate, lysine triisocyanate, hexamethylene diisocyanate, isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate, cyclohexyl diisocyanate (H 12 MDI), 2,2,4-(2,2,4)-trimethylhexamethylene diisocyanate (TMDI), dimers prepared form aliphatic polyisocyanates or trimers prepared from aliphatic polyisocyanates.
20 . The method of claim 19 wherein the polyisocyanate compounds comprise at least one of hexamethylene diisocyanate dimer, hexamethylene diisocyanate trimer, isophorone diisocyanate dimer, or isophorone diisocyanate trimer.
21 . The method of claim 19 wherein the alkyl ester of lysine diisocyanate is lysine diisocyanate methyl ester or lysine diisocyanate ethyl ester.
22 . The method of claim 19 wherein the polyisocyanate compounds comprise lysine triisocyanate.
23 . The method of claim 1 wherein the polyisocyanate component has an average isocyanate functionality of at least 2.
24 . The method of claim 1 wherein the polyisocyanate component has an average isocyanate functionality of at least 2.5.
25 . The method of claim 1 wherein a catalyst is added to the polyester polyol before contacting the quasi-prepolymer with the polyester polyol.
26 . The method of claim 25 wherein the catalyst is a tertiary amine or an organobismuth compound.
27 . The method of claim 1 wherein a crosslinker is added to the polyester polyol before contacting the quasi-prepolymer with the polyester polyol.
28 . The method of claim 27 wherein the crosslinker has a functionality of at least 3 and a molecular weight of no more than 300 g/mol.
29 . The method of claim 27 wherein the crosslinker comprises at least one of glycerol, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, trimethylolpropane, 1,2,3-trihydroxyhexane, myo-inositol, ascorbic acid, a saccharide, or a sugar alcohol.
30 . The method of claim 1 further comprising the step of casting the reactive liquid mixture into a mold.
31 . The method of claim 30 further comprising the step of curing the biodegradable polyurethane in the mold.
32 . The method of claim 1 wherein the flowable quasi-prepolymer comprises free aliphatic polyisocyanate compounds of at least 1% by weight.
33 . The method of claim 1 wherein the flowable quasi-prepolymer comprises free aliphatic polyisocyanate compounds of at least 10% by weight.
34 . The method of claim 1 wherein the flowable quasi-prepolymer comprises free aliphatic polyisocyanate compounds of at least 20% by weight.
35 . The method of claim 2 wherein the polyol component comprises a polyester polyol.
36 . The method of claim 35 wherein the polyester polyol has a functionality greater than 2.0.
37 . The method of claim 35 wherein the polyester polyol has a functionality greater at least 2.5.
38 . The method of claim 36 wherein the polyester polyol comprises hydroxyl-terminated compounds having hydrolysable ester linkages:
39 . The method of claim 38 wherein the polyester polyol comprises a polyalkylene glycol ester or a polyester prepared from at least one cyclic ester.
40 . The method of claim 39 wherein the polyester polyol comprises poly(ethylene adipate), poly(ethylene glutarate), poly(ethylene azelate), poly(trimethylene glutarate), poly(pentamethylene glutarate), poly(diethylene glutarate), poly(diethylene adipate), poly(triethylene adipate), poly(1,2-propylene adipate), a mixture thereof or a copolymer of at least two thereof.
41 . The method of claim 39 wherein the polyester polyol comprises polyesters prepared from castor-oil.
42 . The method of claim 2 wherein the polyol component comprises at least one of glycerol, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, trimethylolpropane, 1,2,3-trihydroxyhexane, myo-inositol, ascorbic acid, a saccharide, or a sugar alcohol.
43 . A quasi-prepolymer formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound wherein an excess of the polyisocyanate component is used to result in free isocyanate component.
44 . A quasi-prepolymer formed by contacting a polyisocyanate component comprising at least one aliphatic polyisocyanate compound with a polyol component comprising at least one polyol compound and subsequently adding polyisocyanate compounds to result in free isocyanate component.
45 . A biodegradable polyurethane formed by contacting a flowable quasi-prepolymer comprising free aliphatic polyisocyanate compounds with a polyester polyol hardener having a functionality of at least two to form a reactive liquid mixture.
46 . The biodegradable polyurethanes of claim 45 having a modulus greater than 837 MPa.
47 . The biodegradable polyurethanes of claim 45 having a compressive strength greater than 61.9 MPa.
48 . (canceled)
49 . (canceled)
50 . The method of claim 39 wherein the polyester polyol comprises polyesters prepared from at least one of ε-caprolactone, glycolide or DL-lactide.