Process for the preparation of heat-stable polyurethane urea elastomers

• US 5,064,875 A
• Filed: 11/30/1990
• Issued: 11/12/1991
• Est. Priority Date: 12/06/1989
• Status: Expired due to Fees

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Thiery, Urs, Hess, Heinrich, Kopp, Richard, Ruckes, Andreas, Grogler, Gerhard
• Primary Examiner(s): WELSH JR, MAURICE
• Application Number:
  US07/620,986
• Time in Patent Office: 347 Days
• Field of Search: 521/159, 521/163, 528/64, 528/79
• US Class Current: 521/159
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/3243 containing two or more aromatic rings
• CPC Class Codes: C08G 18/6529 Compounds of group C08G18/3225 or polyamines of C08G18/38
• CPC Class Codes: C08G 2110/0008 flexible
• CPC Class Codes: C08G 2110/0016 semi-rigid
• CPC Class Codes: C08G 2110/0033 having integral skins
• CPC Class Codes: C08G 2120/00 Compositions for reaction injection moulding processes

Abstract

This invention relates to a process for preparing polyurethane urea elastomers by reacting (a) compounds containing at least two isocyanate-reactive groups and having a molecular weight in the range from about 400 to about 10,000; (b) polyisocyanates; and (c) aromatic diamines corresponding to the formula ##STR1## wherein R¹ and R² are independently hydrogen or alkyl.

Claims

1. A process for the preparation of a polyurethane urea elastomer comprising reacting

(a) a compound containing at least two isocyanate-reactive groups and having a molecular weight in the range from 400 to 10,000;

(b) a polyisocyanate; and

(c) an aromatic diamine corresponding to the formula ##STR6## wherein R¹ and R² are independently hydrogen or alkyl.

2. A process according to claim 1 additionally comprising

(d) auxiliaries and additives.

3. A process according to claim 1 wherein compound (a) has a molecular weight in the range from about 400 to about 6,000.

4. A process according to claim 1 wherein R¹ and R² are independently hydrogen or C₁ -C₆ alkyl.

5. A process according to claim 1 wherein R¹ and R² are independently hydrogen or methyl.

6. A process according to claim 1 wherein aromatic diamine (c) is used as a powder suspended in a portion of component (a) and wherein components (a), (b), and (c) are initially mixed at a temperature below the melting point of said aromatic diamine.

7. A process according to claim 1 wherein an NCO preadduct is initially prepared from components (a) and (b) and wherein aromatic diamine (c) is added as a powder to said NCO preadduct.

8. A process according to claim 1 wherein component (a) is a polyhydroxyl compound in which aromatic diamine (c) is only poorly soluble at temperatures below 100°

C. but in which aromatic diamine (c) is substantially soluble at temperatures of from 130°

to 200°

C.

9. A process according to claim 1 wherein component (a) is a polyester having a molecular weight of 400 to 10,000.

10. A process according to claim 9 wherein the polyester has a molecular weight of 400 to 6,000.

11. A process according to claim 1 wherein aromatic diamine (c) is 1,4-bis(2-(4-aminophenoxy)ethoxy)benzene having the formula ##STR7##

12. A process according to claim 1 wherein aromatic diamine (c) is used as a powder having a particle size of 1 to 100 μ

m.

13. A process according to claim 1 wherein aromatic diamine (c) is used as a powder having a particle size of 1 to 50 μ

m.

14. A process according to claim 1 wherein a suspension is formed by mixing aromatic diamine (c) in powder form with a portion of component (a) in quantities such that the ratio by weight of said aromatic diamine (c) to component (a) is from 1.0.5 to 5:

1.

15. A process according to claim 14 wherein the ratio by weight of aromatic diamine (c) to component (a) is from 1.0:

1.0 to 2.0.

16. A process according to claim 14 wherein the suspension is added as a chain-extending agent to polyisocyanate (b) and the remaining portion of component (a).

17. A process according to claim 14 wherein the suspension is mixed with polyisocyanate (b) in quantities such that 0.05 to 20% NH₂ equivalents of aromatic diamine (c) react in an initial reaction with said polyisocyanate (b).

18. A heterogeneous mixture comprising a mixture of

(A) an NCO-terminated preadduct, wherein said preadduct is prepared by reacting

(a) a compound containing at least two isocyanate-reactive groups and having a molecular weight in the range from 400 to 10,000 and

(b) a polyisocyanate, and

(B) an aromatic diamine corresponding to the formula ##STR8## wherein R¹ and R² are independently hydrogen or alkyl.