Diphenylmethane diisocyanate compositions

Claim 2

A diphenylmethane diisocyanate composition which comprises diphenylmethane diisocyanate, a diphenylmethane diisocyanate uretonimine group-containing derivative, a reaction product of diphenylmethane diisocyanate and a diol of molecular weight less than 175 and not more than 10% by weight of methylene bridged polyphenyl polyisocyanates of isocyanate functionality higher than two, the composition having an isocyanate functionality of not more than 2.3.

Claim 3

A diphenylmethane diisocyanate composition as claimed in claim 1 wherein the diphenylmethane diisocyanate used in the composition and in the preparation of the uretonimine group-containing derivative and the diol/diphenylmethane diisocyanate reaction product has been subjected to at least one purification by distillation or crystallisation.

Claim 4

A diphenylmethane diisocyanate composition as claimed in claim 2 wherein the diphenylmethane diisocyanate has been at least once distilled.

Claim 5

A diphenylmethane diisocyanate composition as claimed in claim 2 wherein the diphenylmethane diisocyanate is diphenylmethane-4,4'-diisocyanate containing up to 50% of the 2,4'-isomer and up to 5% of the 2,2'-isomer thereof.

Claim 6

A diphenylmethane diisocyanate composition as claimed in claim 1 wherein the uretonimine group-containing derivative is made by converting from 3.5 to 35% of the isocyanate groups in diphenylmethane diisocyanate to carbodiimide groups by heating the diisocyanate in the presence of a catalyst, cooling the mixture, deactivating the catalyst if desired and then allowing the carbodiimide groups to react further to give the uretonimine derivative.

Claim 7

A diphenylmethane diisocyanate composition as claimed in claim 1 wherein the reaction product of the diol and diphenylmethane diisocyanate is the reaction product of 0.05 to 0.35 molar proportions of diol with 1 molar proportion of diphenylmethane diisocyanate.

Claim 8

A diphenylmethane diisocyanate composition as claimed in claim 1 having the composition: 30 to 80% of diphenylmethane diisocyanate, 5 to 25% of diphenylmethane diisocyanate uretonimine group-containing derivative, 20 to 50% of a reaction product of diphenylmethane diisocyanate and a diol or mixture of diols of M.W. less than 175 and 0 to 10% of methylene bridged polyphenyl polyisocyanates of isocyanate functionality higher than two, the above percentages being by weight and the average isocyanate functionality of the composition being not more than 2.3.

Claim 9

A process for the manufacture of a diphenylmethane diisocyanate composition as claimed in claim 1 which comprises blending a diphenylmethane diisocyanate diol reaction product with a diphenylmethane diisocyanate uretonimine group-containing derivative and diphenylmethane diisocyanate and optionally methylene bridged polyphenyl polyisocyanates of isocyanate functionality greater than two.

Claim 10

A process for the manufacture of a diphenylmethane diisocyanate composition as claimed in claim 1 which comprises mixing a solution of a uretonimine group-containing derivative of diphenylmethane diisocyanate in diphenylmethane diisocyanate with a diol or mixture of diols under such conditions that urethane formation but no other reaction takes place.

Claim 11

A process for the manufacture of a diphenylmethane diisocyanate composition as claimed in claim 1 wherein diphenylmethane diisocyanate is first treated with a phosphorus-containing catalyst to convert from 10 to 30% of the isocyanate groups to carbodiimide groups which then react with isocyanate groups to give a solution of the uretonimine group-containing derivative in the diisocyanate, there is then added from 50 to 150% of diphenylmethane diisocyanate based on the weight of the original diisocyanate and this mixture is then reacted with one or more diols below 85° C in such amount as to give a final composition having an isocyanate group content of from 22 to 30% and optionally up to 10% by weight of methylene bridged polyphenyl polyisocyanates having an isocyanate functionality greater than two are added to the composition.