Microorganisms immobilized with hydrolysis resistant polyurethane foam

Claim 2

A water insoluble, hydrolysis resistant, hydrophilic polyether polyurea polyurethane foam having aspartase-producing microorganisms bound to the foam prepared by reacting under foaming conditions an aqueous mixture containing a culture of aspartase-producing microorganisms and a hydrophilic polyether polyurethane prepolymer, said foam having a weight ratio of polyurea polyurethane polymer to microorganisms in the foam ranging from about 2 to about 4, a weight ratio of prepolymer to water is from about 2 to about 0.5, and said prepolymer having an isocyanate functionality in excess of 2 but not greater than 8 with at least 50 mole % of the alkylene oxide units in the polyether segments of the polyurethane being ethylene oxide, and obtained by reacting a poly(oxy-C 2-4 alkylene) diol having at least about 50% by weight of oxyethylene groups. a diphenylmethane diisocyanate-containing isocyanate product with a functionality of greater than 2.0 comprising a mixture of diphenylmethane diisocyanate and isocyanate containing derivatives of diphenylmethane diisocyanate, and a polyol cross-linking agent having 3 or 4 hydroxyl equivalents per mole.

Claim 3

A foam according to claim 1, wherein said isocyanate product comprises a mixture of a major amount of pure diphenylmethane diisocyanate and minor amounts of carbodiimides and trifunctional cycloadducts of diphenylmethane diisocyanate.

Claim 4

A foam according to claim 1, wherein said prepolymer is either (A) a prepolymer derived from (a) a poly(oxy C 2-4 alkylene) diol having at least about 50% by weight of oxyethylene groups and a nominal number average molecular weight of about at least 1100, said diol having nominally two hydroxyl equivalents per mole, (b) a diphenylmethane diisocyanate-containing isocyanate product with a functionality of greater than 2.0 comprising a mixture of diphenylmethane diisocyanate and isocyanate containing derivatives of diphenylmethane diisocyanate, and (c) a monomeric polyol crosslinking agent having 3 or 4 hydroxyl equivalents per mole, said isocyanate containing product comprising less than 50% by weight of the prepolymer, said diol and polyol crosslinking agent being present in a mole ratio in the range of about 4:1 to 8:1, and the ratio of the isocyanate equivalents to the total hydroxyl equivalents being in the range of about 2.5:1 to 3.5:1; (B) a prepolymer derived from (a) a poly(oxy C 2-4 alkylene) diol having at least about 50% by weight of oxyethylene groups and a nominal number average molecular weight of about less than 2000, said diol having nominally two hydroxyl equivalents per mole, (b) a diphenylmethane diisocyanate-containing isocyanate product with a functionality of greater than 2.0 comprising a mixture of diphenylmethane diisocyanate and isocyanate containing derivatives of diphenylmethane diisocyanate, and (c) a polymeric poly(oxy C 2-4 alkylene) polyol crosslinking agent having 3 or 4 hydroxyl equivalents per mole, and having a number average molecular weight of at least 500 said isocyanate containing product comprising less than 50% weight of the prepolymer, said polymeric polyol crosslinking agent being present so that the hydroxy equivalents constitute 5 to 35 mole % of the total hydroxy equivalents in the diol and polyol, the ratio of the isocyanate equivalents to the total hydroxyl equivalents being in the range of about 2.5:1 to 3.5:1; or (C) a prepolymer derived from (a) a poly(oxy C 2-4 alkylene) diol having at least about 50% by weight of oxyethylene groups and a nominal number average molecular weight of about at most 1100, said diol having nominally two hydroxyl equivalents per mole, (b) a diphenylmethane diisocyanate-containing isocyanate product with a functionality of greater than 2.0 comprising a mixture of diphenylmethane diisocyanate and isocyanate containing derivatives of diphenylmethane diisocyanate, and (c) a monomeric polyol cross-linking agent having 3 or 4 hydroxyl equivalents per mole, said isocyanate product comprising more than 50% by weight of the prepolymer, said diol and polyol crosslinking agent being present in a mole ratio in the range of 4:1 to 8:1, and the ratio of the isocyanate equivalents to the total hydroxyl equivalents being in the range of 3:1 to 4:1.

Claim 5

A foam according to claim 3, wherein the nominal number average molecular weight of the poly(oxy C 2-4 alkylene) diol in part A is between 1100 and 2000 and the diol has at least 80% by weight of oxyethylene groups and wherein the nominal number average molecular weight of the poly(oxy C 2-4 alkylene) diol in part B is 600-2000 and the diol has preferably at least 80% by weight of oxyethylene groups.

Claim 6

A foam according to claim 4, wherein the nominal number average molecular weight of the poly(oxy C 2-4 alkylene) diol in part A is between 1200 and 1500 and wherein the nominal number average molecular weight of the poly(oxy C 2-4 alkylene) diol in part B is between 950 and 1500.

Claim 7

A foam according to claim 3, wherein the poly(oxy C 2-4 alkylene) diol in part A comprises a mixture of at least 2 diols each having a different nominal number average molecular weight.

Claim 8

A foam according to claim 6, wherein the poly(oxy C 2-4 alkylene) diol in part A comprises a mixture of a diol with a molecular weight of about 1000 and a diol of a molecular weight of about 1450.

Claim 9

A foam according to claim 3, wherein the polyol crosslinking agent in part A and part C is selected from the group consisting of trimethylolpropane, trimethylolethane, glycerol, triethanolamine, pentaerythritol, and mixtures thereof and wherein the polymeric polyol crosslinking agent in part B is selected from the group consisting of a poly(oxyethylene) triol having a molecular weight of about 900, and an oxyethylene-capped poly(oxypropylene) triol having a molecular weight of about 1400 and mixtures thereof.

Claim 10

A foam according to claim 3, wherein the nominal number average molecular weight of the poly(oxy C 2-4 alkylene) diol in part C is between 600 and 1100 and the diol has at least 80% by weight of oxyethylene groups.

Claim 11

A foam according to claim 3, wherein said isocyanate product comprises a mixture of a major amount of pure diphenylmethane diisocyanate and minor amounts of carbodiimides and trifunctional cycloadducts of diphenylmethane diisocyanate.

Claim 12

A process for preparing L-aspartic acid wherein a substrate comprising fumarate ion is contacted with the foam according to claim 1.

Claim 13

A process as in claim 11, wherein the substrate has a pH of from 8 to 10.

Claim 14

A process as in claim 11, wherein the temperature of the substrate is from 15° C. to 60° C.

Claim 15

A process as in claim 11, wherein the substrate comprises ammonium fumarate.

Claim 16

A process as in claim 11, wherein the substrate comprises magnesium ion.

Claim 17

A process as in claim 11, said process carried out on a continuous basis.

Claim 18

A process as in claim 11, said process carried out on a batch basis.

Claim 19

A process for preparing L-aspartic acid wherein a substrate comprising fumarate ion is contacted with the foam according to claim 2.

Claim 20

A process for preparing L-aspartic acid wherein a substrate comprising fumarate ion is contacted with the foam according to claim 3.