Preparation of carbodiimide-containing polyisocyanates

• US 4,143,063 A
• Filed: 04/10/1978
• Issued: 03/06/1979
• Est. Priority Date: 01/31/1977
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Upjohn Company (Pharmacia Corp.)
• Inventors: Smith, Curtis P., Alberino, Louis M.
• Primary Examiner(s): Torrence, Dolph H.
• Application Number:
  US05/894,737
• Time in Patent Office: 330 Days
• Field of Search: 260/453 AR, 260/453 AL, 260/453 AM, 260/566 R, 260/453 SP, 260/25 BF
• US Class Current: 560/334
• CPC Class Codes: B01J 31/069 Hybrid organic-inorganic polymers, e.g. silica derivatized with organic groups nitrogen containing groups on mineral substrates B01J31/0254; organometallic polymers B01J31/123; coordination complexes immobilised on an inorganic support B01J31/1616; coordination polymers, e.g. metal-organic frameworks B01J31/1691
• CPC Class Codes: C08F 12/04 containing one ring
• CPC Class Codes: C08F 8/42 Introducing metal atoms or metal-containing groups
• CPC Class Codes: C08G 18/797 containing carbodiimide and/or uretone-imine groups

Abstract

A process is described for converting organic polyisocyanates to carbodiimide-containing polyisocyanates by heating said organic polyisocyanates in the presence of an organoarsine-substituted polystyrene carbodiimide-forming catalyst until a desired level of conversion is achieved, followed by separation of catalyst from product. It is thus possible to obtain a carbodiimide-containing polyisocyanate which is free from catalyst and hence free from the possibility that carbodiimide formation can continue on storage of the product. In a particular embodiment the process is employed to convert methylenebis(phenyl isocyanate), which is normally solid at ambient temperatures, to a storage stable liquid product. The polymeric catalysts employed in the process are characterized by a recurring unit of the formula: ##STR1## wherein R₁ and R₂ are hydrocarbyl, R₃ is hydrogen, chloro or methyl, R₄ is hydrogen or methyl and n is 0 or 1.

Claims

1. A process for preparing a carbodiimide-containing organic polyisocyanate said process comprising:

heating an organic polyisocyanate to a temperature in the range of about 70°

C. to about 200°

C. in the presence of a catalytic amount of a polymer characterized in that from 0.1 percent to 100 percent of the recurring units have the formula ##STR14## wherein R₁ and R₂ are hydrocarbyl free from substituents reactive with isocyanate groups, R₃ is selected from the class consisting of hydrogen, chloro and methyl, R₄ is selected from the class consisting of hydrogen and methyl, and n is an integer from 0 to 1 and the remainder of the recurring units in said polymer have the formula ##STR15## wherein R₄ and R₃ are as above defined;

continuing said heating until the desired proportion of carbodiimide-formation has occurred; and

stopping said reaction by separating the solid catalyst from the carbodiimide containing organic polyisocyanate.

2. The process of claim 1 wherein the recurring unit (I) has the formula:

##STR16##

3. The process of claim 1 wherein said organic polyisocyanate is methylenebis(phenyl isocyanate).

4. The process of claim 1 wherein said organic polyisocyanate is a toluene diisocyanate selected from the class consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures thereof.

5. A process for preparing a storage stable liquid form of methylenebis(phenyl isocyanate) which comprises

heating methylenebis(phenyl isocyanate) at a temperature in the range of about 70°

C. to about 200°

C. in the presence of a catalytic quantity of a polymer characterized in that from 0.1 percent to 100 percent of the recurring units have the formula;

##STR17## wherein R₁ and R₂ are hydrocarbyl free from substituents reactive with isocyanate groups, R₃ is selected from the class consisting of hydrogen, chloro and methyl, R₄ is selected from the class consisting of hydrogen and methyl and n is an integer from 0 to 1 and the remainder of the recurring units of said polymer have the formula ##STR18## wherein R₃ and R₄ are as defined above;

continuing said heating until from about 3 percent to about 25 percent of the isocyanate groups in said methylenebis(phenyl isocyanate) have been converted to carbodiimide groups; and

thereupon separating the solid catalyst from the liquid polyisocyanate.

6. The process of claim 5 wherein the recurring unit (I) has the formula:

##STR19##

7. The process of claim 5 wherein said methylenebis(phenyl isocyanate) employed as starting material contains from about 85 percent to about 98 percent of the 4,4'"'"'-isomer.

8. The process of claim 5 wherein said methylenebis(phenyl isocyanate) employed as starting material is present in admixture with oligomeric polymethylene polyphenyl polyisocyanates.