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.

The present disclosure relates to a diisocyanate stabilizer, use of the diisocyanate stabilizer for stabilizing diisocyanate, and a diisocyanate composition comprising the stabilizer. The diisocyanate stabilizer comprises a sterically hindered phenol other than butylated hydroxytoluene, a thioether, and a phosphite other than triphenyl phosphite. The present disclosure aims to provide a diisocyanate stabilizer which can make diisocyanates maintain stable during long-term storage and heating condition.

The present disclosure relates to a diisocyanate stabilizer, use of the diisocyanate stabilizer for stabilizing diisocyanate, and a diisocyanate composition comprising the stabilizer. The diisocyanate stabilizer comprises a sterically hindered phenol other than butylated hydroxytoluene, a thioether, and a phosphite other than triphenyl phosphite. The present disclosure aims to provide a diisocyanate stabilizer which can make diisocyanates maintain stable during long-term storage and heating condition.

The present invention relates to a polyisocyanate composition comprising, on the basis of the total mass of the polyisocyanate composition, 97 mass % or more of a polyisocyanate; and 2.0 mass ppm to 1.010.sup.4 mass ppm of a compound represented by the formula (1): ##STR00001## wherein R.sup.1 is an aliphatic group having 6 to 70 carbon atoms, R.sup.2 is an aromatic ring, a is an integer of 1 to 5, b is an integer of 0 to 4, and the sum of a and b is 2 to 5.

The present invention relates to a polyisocyanate composition comprising, on the basis of the total mass of the polyisocyanate composition, 97 mass % or more of a polyisocyanate; and 2.0 mass ppm to 1.010.sup.4 mass ppm of a compound represented by the formula (1): ##STR00001## wherein R.sup.1 is an aliphatic group having 6 to 70 carbon atoms, R.sup.2 is an aromatic ring, a is an integer of 1 to 5, b is an integer of 0 to 4, and the sum of a and b is 2 to 5.

The xylylene diisocyanate composition according to the embodiments has a chlorine content of 100 to 1,000 ppm to improve the stability, so that the degradation of the reactivity can be prevented even when it is stored for a long period of time. Therefore, even if the xylylene diisocyanate composition according to the embodiments is used after it has been stored for a long period of time for sale or the like, the xylylene diisocyanate composition can be polymerized with a thiol to produce a polythiourethane-based optical material having excellent properties such as refractive index, Abbe number, transparency, glass transition temperature, yellowness index, and the like. Therefore, it can be advantageously used in the field of eyeglass lenses, camera lenses, and the like.

The xylylene diisocyanate composition according to the embodiments has a chlorine content of 100 to 1,000 ppm to improve the stability, so that the degradation of the reactivity can be prevented even when it is stored for a long period of time. Therefore, even if the xylylene diisocyanate composition according to the embodiments is used after it has been stored for a long period of time for sale or the like, the xylylene diisocyanate composition can be polymerized with a thiol to produce a polythiourethane-based optical material having excellent properties such as refractive index, Abbe number, transparency, glass transition temperature, yellowness index, and the like. Therefore, it can be advantageously used in the field of eyeglass lenses, camera lenses, and the like.

The present invention relates to a polyisocyanate composition comprising, on the basis of the total mass of the polyisocyanate composition, 97 weight % or more of a polyisocyanate, and 2.0 mass ppm or more and 1.010.sup.4 mass ppm or less of a compound having at least one unsaturated bond in which the compound is a different compound from the polyisocyanate, or 5.0 mass ppm or more and 2.010.sup.4 mass ppm or less of at least one inactive compound selected from the group consisting of a hydrocarbon compound, an ether compound, a sulfide compound, a halogenated hydrocarbon compound, a Si-containing hydrocarbon compound, a Si-containing ether compound, and a Si-containing sulfide compound.

The present invention relates to a polyisocyanate composition comprising, on the basis of the total mass of the polyisocyanate composition, 97 weight % or more of a polyisocyanate, and 2.0 mass ppm or more and 1.010.sup.4 mass ppm or less of a compound having at least one unsaturated bond in which the compound is a different compound from the polyisocyanate, or 5.0 mass ppm or more and 2.010.sup.4 mass ppm or less of at least one inactive compound selected from the group consisting of a hydrocarbon compound, an ether compound, a sulfide compound, a halogenated hydrocarbon compound, a Si-containing hydrocarbon compound, a Si-containing ether compound, and a Si-containing sulfide compound.