Abstract: 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 of higher quality, in which the reaction temperature of a diamine hydrochloride composition and triphosgene is controlled to a specific range, or a crude diisocyanate composition obtained from the reaction of a diamine hydrochloride composition and triphosgene is distilled at a specific temperature range, or the molar ratio of a diamine hydrochloride and triphosgene is adjusted to a specific range.

Abstract: 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 of higher quality by controlling the water content in the diamine hydrochloride composition for preparing a diisocyanate within a specific range.

Abstract: 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.

Abstract: A diamine composition comprising a benzylmonoamine having a methyl group in an amount of 10 ppm to 2,000 ppm in the composition and use thereof for the preparation of a diisocyanate composition and an optical material. A process for preparing a diisocyanate composition wherein the b* value according to the CIE color coordinate of the diamine composition is adjusted to a specific range, whereby the yield and purity of the diisocyanate composition and the optical characteristics of the final optical lens are enhanced. Use of the process for the diisocyanate composition for preparing a plastic optical lens of high quality.

Abstract: 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 of high quality in which the content of water, the content of cations, or the content of an aromatic compound containing 3 or more of chlorine (Cl) in the organic solvent used in the reaction of a diamine hydrochloride composition and triphosgene is adjusted to a specific range.

Abstract: According to an embodiment, the pH of a diisocyanate composition and a diamine hydrochloride composition used in the preparation of an optical lens 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 by suppressing the striae and cloudiness. Specifically, according to the process of the embodiment, the amount of an aqueous hydrochloric acid solution introduced to the reaction may be adjusted to control the pH of the diisocyanate composition to a desired range, thereby enhancing the yield and purity. Accordingly, the process for preparing a diisocyanate composition according to the embodiment can be applied to the preparation of a plastic optical lens of high quality.

Abstract: 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 using a solid triphosgene composition instead of phosgene gas in the process of preparing a diisocyanate from a diamine through a hydrochloride thereof and by controlling the content of a decomposition product in a triphosgene composition, the b* value according to CIE color coordinate of the triphosgene composition in an organic solvent, or the content of water in the triphosgene.

Abstract: The embodiments relate to a process for preparing a polythiol composition, which comprises reacting a halogen compound or an alcohol compound with thiourea to prepare a thiouronium salt solution; and adding a basic solution to the thiouronium salt solution to hydrolyze it. The hydrolysis reaction is terminated when the area of peak A in the graph measured by gel permeation chromatography of the reactant in the hydrolysis step under certain conditions is 0.5% to 8% based on the total peak area. A tetrafunctional polythiol composition having high purity can be obtained. Thus, an optical lens having excellent color, transparency, and refractive index can be obtained.

Abstract: In the embodiments, an aqueous hydrochloric acid solution and an organic solvent 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 total content of metals, cations, or anions in a diamine hydrochloride composition.

Abstract: 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.

Abstract: 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.

Abstract: 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 of higher quality by controlling the water content in the diamine hydrochloride composition for preparing a diisocyanate within a specific range.

Abstract: The embodiments relate to a process for preparing a polythiol composition, which comprises reacting a halogen compound or an alcohol compound with thiourea to prepare a thiouronium salt solution; and adding a basic solution to the thiouronium salt solution to hydrolyze it. The hydrolysis reaction is terminated when the area of peak A in the graph measured by gel permeation chromatography of the reactant in the hydrolysis step under certain conditions is 0.5% to 8% based on the total peak area. A tetrafunctional polythiol composition having high purity can be obtained. Thus, an optical lens having excellent color, transparency, and refractive index can be obtained.

Abstract: According to an embodiment, the pH of a diisocyanate composition and a diamine hydrochloride composition used in the preparation of an optical lens 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 by suppressing the striae and cloudiness. Specifically, according to the process of the embodiment, the amount of an aqueous hydrochloric acid solution introduced to the reaction may be adjusted to control the pH of the diisocyanate composition to a desired range, thereby enhancing the yield and purity. Accordingly, the process for preparing a diisocyanate composition according to the embodiment can be applied to the preparation of a plastic optical lens of high quality.

Abstract: 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 of higher quality by controlling the water content in the diamine hydrochloride composition for preparing a diisocyanate within a specific range.

Abstract: The diisocyanate composition according to an embodiment of the present invention comprises, in the composition, a benzyl isocyanate having a methyl group in an amount of 5 ppm to 200 ppm, an aromatic compound having a halogen group in an amount of 5 ppm to 1,000 ppm, a benzyl isocyanate having an ethyl group in an amount of 1 ppm to 1,000 ppm, or a combination thereof. It is possible to improve the optical characteristics by preventing the occurrence of yellowing, striae, and cloudiness and to enhance the mechanical properties such as impact resistance at the same time. Thus, it can be advantageously used to prepare an optical material of high quality.

Abstract: 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.

Abstract: 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 using a solid triphosgene composition instead of phosgene gas in the process of preparing a diisocyanate from a diamine through a hydrochloride thereof and by controlling the content of a decomposition product in a triphosgene composition, the b* value according to CIE color coordinate of the triphosgene composition in an organic solvent, or the content of water in the triphosgene.

Abstract: 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 of higher quality, in which the reaction temperature of a diamine hydrochloride composition and triphosgene is controlled to a specific range, or a crude diisocyanate composition obtained from the reaction of a diamine hydrochloride composition and triphosgene is distilled at a specific temperature range, or the molar ratio of a diamine hydrochloride and triphosgene is adjusted to a specific range.

Abstract: In the embodiments, an aqueous hydrochloric acid solution and an organic solvent 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 total content of metals, cations, or anions in a diamine hydrochloride composition.