The invention relates to a novel method for preparing carbodiimides.

The invention relates to a novel method for preparing carbodiimides.

Disclosed is a light colored modified isocyanate mixture and a preparation method thereof. The method comprises the following steps: a) reacting isocyanate groups of a raw material isocyanate under the action of a phospholenecatalyst, and finally obtaining a modified isocyanate reaction solution containing carbodiimide and/or uretonimine derivatives; and b) adding a compounded terminator of a halosilane organic and a sulfonic anhydride to the reaction solution obtained in step a so as to terminate the reaction of carbodiimidization. The modified isocyanate prepared by the method has the characteristics of a liquid state at room temperature, being stable in storage at room temperature and high temperature, and low color number.

Disclosed is a light colored modified isocyanate mixture and a preparation method thereof. The method comprises the following steps: a) reacting isocyanate groups of a raw material isocyanate under the action of a phospholenecatalyst, and finally obtaining a modified isocyanate reaction solution containing carbodiimide and/or uretonimine derivatives; and b) adding a compounded terminator of a halosilane organic and a sulfonic anhydride to the reaction solution obtained in step a so as to terminate the reaction of carbodiimidization. The modified isocyanate prepared by the method has the characteristics of a liquid state at room temperature, being stable in storage at room temperature and high temperature, and low color number.

The invention relates to a process for preparing liquid, storage-stable isocyanate mixtures having carbodiimide (CD) and/or uretonimine (UI) groups or prepolymers derived therefrom, wherein (i) in a first step, a starting isocyanate which is an organic isocyanate or a mixture of two or more organic isocyanates is partly carbodiimidized with a catalyst K of the formula cyclo-C.sub.4H.sub.6P(O)R, where the substituent R is a saturated or unsaturated, optionally substituted, especially halogen-substituted, organic radical, and then (ii) in a second step, the carbodiimidization reaction is stopped at a temperature of 80 C. by adding a stopper, the stopper used being an organic silane S of the general formula H.sub.nSiX.sub.4-n, where n is a natural number in the range from 1 to 3, where X is a saturated or unsaturated, optionally substituted, especially halogen-substituted, organic radical.

The invention relates to a process for preparing liquid, storage-stable isocyanate mixtures having carbodiimide (CD) and/or uretonimine (UI) groups or prepolymers derived therefrom, wherein (i) in a first step, a starting isocyanate which is an organic isocyanate or a mixture of two or more organic isocyanates is partly carbodiimidized with a catalyst K of the formula cyclo-C.sub.4H.sub.6P(O)R, where the substituent R is a saturated or unsaturated, optionally substituted, especially halogen-substituted, organic radical, and then (ii) in a second step, the carbodiimidization reaction is stopped at a temperature of 80 C. by adding a stopper, the stopper used being an organic silane S of the general formula H.sub.nSiX.sub.4-n, where n is a natural number in the range from 1 to 3, where X is a saturated or unsaturated, optionally substituted, especially halogen-substituted, organic radical.

An object of the present invention is to provide a bismaleimide using an aliphatic diamine, in which acid components remaining as an impurity at a very small amount in the bismaleimide have been effectively removed, that is, a bismaleimide using an aliphatic diamine, an acid value of which has sufficiently been reduced, and a method for producing it. There are provided a bismaleimide using an aliphatic diamine as a diamine component, characterized in that an acid value thereof is 2 mg-KOH/g or less, and a method for producing the bismaleimide, comprising adding carbodiimide to a solution comprising a crude bismaleimide having an acid value of more than 2 mg-KOH/g, and reacting acid components in the crude bismaleimide with carbodiimide.

An object of the present invention is to provide a bismaleimide using an aliphatic diamine, in which acid components remaining as an impurity at a very small amount in the bismaleimide have been effectively removed, that is, a bismaleimide using an aliphatic diamine, an acid value of which has sufficiently been reduced, and a method for producing it. There are provided a bismaleimide using an aliphatic diamine as a diamine component, characterized in that an acid value thereof is 2 mg-KOH/g or less, and a method for producing the bismaleimide, comprising adding carbodiimide to a solution comprising a crude bismaleimide having an acid value of more than 2 mg-KOH/g, and reacting acid components in the crude bismaleimide with carbodiimide.

An object is to provide a method for easily producing maleimide (MI) in which trace amounts of residual acid components as impurities in a crude MI are efficiently reduced, that is, the acid value is sufficiently reduced. <1> A method for producing purified MI, comprising reducing an acid value of crude MI by 50% or more, by adding carbodiimide (CDI) to a solution comprising the crude MI to react an acid component in the crude MI with the CDI. <2> The method for producing purified MI, comprising adding 0.5% by mass or more and 8% by mass or less of the CDI with respect to a mass of the crude MI for reaction. <3> The method for producing purified MI, wherein the CDI is N,N-diisopropyl carbodiimide (DIC). <4> The method for producing purified MI, comprising removing a urea derivative of the CDI (CDI-U) by-produced when reacting the acid component in the crude MI with the CDI.

An object is to provide a method for easily producing maleimide (MI) in which trace amounts of residual acid components as impurities in a crude MI are efficiently reduced, that is, the acid value is sufficiently reduced. <1> A method for producing purified MI, comprising reducing an acid value of crude MI by 50% or more, by adding carbodiimide (CDI) to a solution comprising the crude MI to react an acid component in the crude MI with the CDI. <2> The method for producing purified MI, comprising adding 0.5% by mass or more and 8% by mass or less of the CDI with respect to a mass of the crude MI for reaction. <3> The method for producing purified MI, wherein the CDI is N,N-diisopropyl carbodiimide (DIC). <4> The method for producing purified MI, comprising removing a urea derivative of the CDI (CDI-U) by-produced when reacting the acid component in the crude MI with the CDI.