Provided is a polythiol composition including a polythiol compound (A) and a compound represented by the following Formula (1), wherein, in high performance liquid chromatography measurement, a peak area of the compound represented by Formula (1) is 9.0 or less with respect to a total peak area 100 of all compounds contained in the polythiol composition. In Formula (1), X represents a carbon atom or a sulfur atom.

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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.

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.

A method for producing an optical component, the method including: a step of injecting a polymerizable composition including a polythiol component and a polyisocyanate component into a molding die using a tube; and a step of polymerizing the polymerizable composition, wherein a percentage content of a plasticizer in the tube is 20% by mass or less.

A method for producing an optical component, the method including: a step of injecting a polymerizable composition including a polythiol component and a polyisocyanate component into a molding die using a tube; and a step of polymerizing the polymerizable composition, wherein a percentage content of a plasticizer in the tube is 20% by mass or less.

A polythiol composition includes a polythiol compound (A) including at least one of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, or 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and a polythiol compound (B) that is 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane.

A polythiol composition includes a polythiol compound (A) including at least one of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, or 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and a polythiol compound (B) that is 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane.

Provided is a benzotriazole compound represented by Formula (1). In Formula (1), R.sub.1 to R.sub.4 represent substituents. In Formula (1), n1 represents an integer from 0 to 4, and n2 represents an integer from 0 to 3.

Provided is a benzotriazole compound represented by Formula (1). In Formula (1), R.sub.1 to R.sub.4 represent substituents. In Formula (1), n1 represents an integer from 0 to 4, and n2 represents an integer from 0 to 3.

A polymerizable composition for an optical material containing two or more different monomers for an optical material, and a polymerization catalyst, in which at least one of the two or more different monomers for an optical material is an isocyanate compound containing an aromatic ring, a content of the polymerization catalyst with respect to a total of 100 parts by mass of the two or more different monomers for an optical material is from 0.010 parts by mass to 0.50 parts by mass, and the viscosity measured by a B-type viscometer at 25° C. and 60 rpm is from 10 mPa.Math.s to 1,000 mPa.Math.s.