The diamine composition according to an embodiment of the present invention comprises a benzylmonoamine having a methyl group in an amount of 10 ppm to 2,000 ppm in the composition. When it is used for the preparation of a diisocyanate composition and an optical material, it is possible to improve the optical characteristics by preventing the occurrence of yellowing, striae, and cloudiness in the optical material and enhancing the mechanical properties such as impact resistance at the same time. In addition, in the process for preparing a diisocyanate composition according to another embodiment, the b* value according to the CIE color coordinate of a diamine composition is adjusted to a specific range, whereby it is possible to enhance not only the yield and purity of the diisocyanate composition but also the optical characteristics of the final optical lens. Thus, the process for preparing a diisocyanate composition can be applied to the preparation of a plastic optical lens of high quality.

The invention relates to a process for purifying at least one isocyanate selected from the group consisting of aliphatic, cycloaliphatic, araliphatic isocyanates and mixtures thereof, to a process for producing at least one isocyanate selected from the group consisting of aliphatic, cycloaliphatic, araliphatic isocyanates and mixtures thereof, to the isocyanate obtainable by this process, to a polyurethane constructed from at least one such isocyanate, to the use of this isocyanate and to an optical component containing at least one polyurethane according to the invention.

The invention relates to a process for purifying at least one isocyanate selected from the group consisting of aliphatic, cycloaliphatic, araliphatic isocyanates and mixtures thereof, to a process for producing at least one isocyanate selected from the group consisting of aliphatic, cycloaliphatic, araliphatic isocyanates and mixtures thereof, to the isocyanate obtainable by this process, to a polyurethane constructed from at least one such isocyanate, to the use of this isocyanate and to an optical component containing at least one polyurethane according to the invention.

The invention relates to a process for purifying at least one isocyanate selected from the group consisting of aliphatic, cycloaliphatic, araliphatic isocyanates and mixtures thereof, to a process for producing at least one isocyanate selected from the group consisting of aliphatic, cycloaliphatic, araliphatic isocyanates and mixtures thereof, to the isocyanate obtainable by this process, to a polyurethane constructed from at least one such isocyanate, to the use of this isocyanate and to an optical component containing at least one polyurethane according to the invention.

The invention relates to a composition excellent in stability during storage and stability during utilization, and relates to a method of producing the composition. The composition includes a compound (A) represented by general formula (1) and a compound (B) represented by general formula (2), and includes 0.00002 to 0.2 parts by mass of the compound (B) with respect to 100 parts by mass of the compound (A),
(R.sub.1—COO).sub.n—R.sub.2—(NCO).sub.m  (1)
(R.sub.1—COO).sub.n—R.sub.2—(R.sub.3—R.sub.1).sub.m  (2)
wherein in general formulae (1) and (2), R.sub.1 is an ethylenically unsaturated group having 2 to 7 carbon atoms; R.sub.2 is a (m+n)-valent hydrocarbon group having 1 to 7 carbon atoms and optionally contains an ether group; R.sub.1 and R.sub.2 in the general formula (1) are the same as R.sub.1 and R.sub.2 in the general formula (2); in general formula (2), R.sub.3 is —NHC(═O)—; and n and m each represent an integer of one or two.

The invention relates to a composition excellent in stability during storage and stability during utilization, and relates to a method of producing the composition. The composition includes a compound (A) represented by general formula (1) and a compound (B) represented by general formula (2), and includes 0.00002 to 0.2 parts by mass of the compound (B) with respect to 100 parts by mass of the compound (A),
(R.sub.1—COO).sub.n—R.sub.2—(NCO).sub.m  (1)
(R.sub.1—COO).sub.n—R.sub.2—(R.sub.3—R.sub.1).sub.m  (2)
wherein in general formulae (1) and (2), R.sub.1 is an ethylenically unsaturated group having 2 to 7 carbon atoms; R.sub.2 is a (m+n)-valent hydrocarbon group having 1 to 7 carbon atoms and optionally contains an ether group; R.sub.1 and R.sub.2 in the general formula (1) are the same as R.sub.1 and R.sub.2 in the general formula (2); in general formula (2), R.sub.3 is —NHC(═O)—; and n and m each represent an integer of one or two.

In the embodiments, an aqueous hydrochloric acid solution instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by controlling the size of the diamine hydrochloride composition, the b* value according to the CIE color coordinate of the diamine hydrochloride composition, or the content of water in the diamine hydrochloride composition within a specific range.

In the embodiments, an aqueous hydrochloric acid solution instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by controlling the size of the diamine hydrochloride composition, the b* value according to the CIE color coordinate of the diamine hydrochloride composition, or the content of water in the diamine hydrochloride composition within a specific range.

Provided is a process for separating an organic isocyanate prepared by reacting an organic amine with a stoichiometric excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, the process comprising the steps of (i) at least partially condensing the crude product stream containing at least the isocyanate, hydrogen chloride and unconverted phosgene by contacting with at least one liquid stream containing at least one quench liquid in a first separation apparatus to obtain a liquid stream containing at least some of the quench liquid and some of the isocyanate and a gas stream containing at least hydrogen chloride, evaporated quench liquid and phosgene, (ii) discharging the liquid stream obtained in step (i) via a first liquid outlet and of the gas stream obtained in (i) via a first gas conduit and (iii) at least partially condensing and/or absorbing the gas stream discharged in step (ii) through the first gas conduit, wherein that the at least partial condensation and/or absorption is effected in step (iii) by direct introduction of at least one cooling fluid, wherein the cooling fluid is introduced directly into the first gas conduit via at least one addition unit assigned to the first gas conduit.

Provided is a process for separating an organic isocyanate prepared by reacting an organic amine with a stoichiometric excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, the process comprising the steps of (i) at least partially condensing the crude product stream containing at least the isocyanate, hydrogen chloride and unconverted phosgene by contacting with at least one liquid stream containing at least one quench liquid in a first separation apparatus to obtain a liquid stream containing at least some of the quench liquid and some of the isocyanate and a gas stream containing at least hydrogen chloride, evaporated quench liquid and phosgene, (ii) discharging the liquid stream obtained in step (i) via a first liquid outlet and of the gas stream obtained in (i) via a first gas conduit and (iii) at least partially condensing and/or absorbing the gas stream discharged in step (ii) through the first gas conduit, wherein that the at least partial condensation and/or absorption is effected in step (iii) by direct introduction of at least one cooling fluid, wherein the cooling fluid is introduced directly into the first gas conduit via at least one addition unit assigned to the first gas conduit.