Polymerizable composition for optical materials, polymerizable prepolymer composition for optical materials, cured product, and method for producing an optical material

Abstract

The polymerizable composition for an optical material of the present disclosure contains two or more different monomers for an optical material, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, and at least one of the two or more different monomers for an optical material is an isocyanate compound, and the viscosity measured at 25°C and 60 rpm with a B-type viscometer is 10 mPa·s to 1000 mPa·s.

Description

Technical Field

[0001] The present disclosure relates to a polymerizable composition for an optical material, a polymerizable prepolymer composition for an optical material, a cured product, and a method for producing an optical material.

Background Art

[0002] As a method for producing a resin used for an optical material for a plastic lens, for example, there is a casting polymerization method in which a polymerizable composition containing a monomer is injected into a mold and heat-cured. In the casting polymerization method, after preparing and degassing the polymerizable composition, the polymerizable composition is injected into a mold, and through heat curing (polymerization reaction), the product is taken out of the mold (demolded) and annealed to obtain an optical material (for example, a lens, a semi-finished blank, etc.). In the casting polymerization method, in order to improve the quality of the optical material, it is common to carry out the polymerization reaction over a long period of time (for example, about 20 hours to 48 hours) while gradually increasing the temperature of the polymerizable composition by heating. For this reason, it is known that a large proportion (for example, about 90%) of the total time required for producing the optical material is spent on heat polymerization.

[0003] In the examples of Patent Document 1, it is described that a mold injected with a polymerizable composition was gradually heated from 10°C to 120°C and polymerized for 20 hours to obtain a molded body.

[0004] Also, in the examples of Patent Document 2, it is described that a mold injected with a polymerizable composition was gradually heated from 25°C over 16 hours to rise to 120°C and heated at 120°C for 4 hours to obtain a molded body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] The polymerizable composition used in the methods described in Patent Document 1 and Patent Document 2 has a high rate of increase in viscosity after preparation, and there is room for improvement in pot life. The problem to be solved by one embodiment of the present disclosure is to provide a polymerizable composition and a polymerizable prepolymer composition that can shorten the production time of an optical material and have an excellent pot life. Another problem to be solved by one embodiment of the present disclosure is to provide a method for producing an optical material and a cured product using the above polymerizable composition or polymerizable prepolymer composition.

MEANS FOR SOLVING THE PROBLEMS

[0007] <1> It contains two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, at least one of the two or more different monomers for optical materials is an isocyanate compound, A polymerizable composition for an optical material having a viscosity of 10 mPa·s to 1000 mPa·s as measured with a B-type viscometer at 25°C and 60 rpm. <2> At least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, The polymerizable composition for an optical material according to <1>, wherein the content of the basic polymerization catalyst is 0.010 parts by mass to 0.50 parts by mass with respect to 100 parts by mass in total of the two or more different monomers for optical materials. <3> At least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, The polymerizable composition for an optical material according to <1>, wherein the content of the basic polymerization catalyst is more than 0.05 parts by mass and 2.0 parts by mass or less with respect to 100 parts by mass in total of the two or more different monomers for optical materials. <4>The polymerizable composition for an optical material according to any one of <1> to <3>, further comprising a prepolymer which is a polymer of two or more different monomers for an optical material and has a polymerizable functional group. <5>The polymerizable composition for an optical material according to any one of <1> to <4>, wherein the two or more different monomers for an optical material further comprise at least one active hydrogen compound selected from the group consisting of a polythiol compound having two or more mercapto groups, a hydroxy thiol compound containing one or more mercapto groups and one or more hydroxyl groups, a polyol compound containing two or more hydroxyl groups, and an amine compound. <6>The polymerizable composition for an optical material according to any one of <1> to <5>, wherein at least one of the two or more different monomers for an optical material is an active hydrogen compound, and the total proportion of the isocyanate compound and the active hydrogen compound in the total of the two or more different monomers for an optical material is more than 70% by mass. <7>The polymerizable composition for an optical material according to any one of <1> to <6>, wherein the number of moles of the functional group of the organic acid having a pKa value of less than 4 is less than the number of moles of the functional group of the basic polymerization catalyst. <8>The polymerizable composition for an optical material according to any one of <1> to <7>, wherein the basic polymerization catalyst includes a basic polymerization catalyst having a pKa value of 4 to 8. <9>Comprising a prepolymer which is a polymer of two or more different monomers for an optical material and has a polymerizable functional group, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein at least one of the two or more different monomers for an optical material is an isocyanate compound, A polymerizable prepolymer composition for an optical material having a viscosity of 10 mPa·s to 2000 mPa·s measured at 25 °C and 60 rpm with a B-type viscometer. <10>The polymerizable prepolymer composition for an optical material according to <9>, wherein at least one of the two or more different monomers for an optical material is an isocyanate compound having an aromatic ring, and the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the prepolymer is 0.002 parts by mass to 1 part by mass. <11>At least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, The content of the basic polymerization catalyst with respect to 100 parts by mass in total of the prepolymer is 0.1 part by mass to 4.0 parts by mass, The polymerizable prepolymer composition for an optical material according to <9>. <12>A cured product of the polymerizable composition for an optical material according to any one of <1> to <8> or the polymerizable prepolymer composition for an optical material according to any one of <9> to <11>. <13>Comprising two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, A preparation step of preparing a polymerizable composition for an optical material, wherein at least one of the two or more different monomers for optical materials is an isocyanate compound, A casting step of adjusting the viscosity of the polymerizable composition for an optical material measured at 25 ° C. and 60 rpm with a B-type viscometer to 10 mPa·s to 1000 mPa·s and casting the polymerizable composition for an optical material into a mold, A curing step of curing the polymerizable composition for an optical material by polymerizing the two or more different monomers for optical materials in the polymerizable composition for an optical material in the mold, A method for producing an optical material, including <14>At least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, The method for producing an optical material according to <13>, wherein the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is 0.010 part by mass to 0.50 part by mass. <15>At least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, The method for producing an optical material according to <13>, wherein the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is more than 0.05 part by mass and 2.0 parts by mass or less. <16>A preparation step of preparing two or more different monomers for optical materials and a basic polymerization catalyst, Mixing a part of the two or more different monomers for optical materials and at least a part of the basic polymerization catalyst, and polymerizing at least a part of the part of the two or more different monomers for optical materials to obtain a prepolymer, thereby obtaining a mixture containing the prepolymer, which is a prepolymerization step; An acid addition step of adding an organic acid having a pKa value of less than 4 to the mixture containing the prepolymer, which includes; A method for producing an optical material, wherein at least one of the two or more different monomers for optical materials is an isocyanate compound. <17>At least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, The method for producing an optical material according to <16>, wherein the total amount of the two or more different monomers for optical materials is 100 parts by mass, and the amount of the basic polymerization catalyst is 0.010 parts by mass to 0.50 parts by mass. <18>At least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, The method for producing an optical material according to <16>, wherein the total amount of the two or more different monomers for optical materials is 100 parts by mass, and the amount of the basic polymerization catalyst is more than 0.05 parts by mass and 2.0 parts by mass or less. <19>Furthermore, by adding at least the remainder of the two or more different monomers for optical materials to the mixture containing the prepolymer, an optically polymerizable composition for an optical material containing the two or more different monomers for optical materials, the prepolymer, the basic polymerization catalyst, and an organic acid having a pKa value of less than 4 is obtained, which is a step for producing an optically polymerizable composition for an optical material; A curing step of curing the two or more different monomers for optical materials in the optically polymerizable composition for an optical material to obtain an optical material which is a cured product of the optically polymerizable composition for an optical material, which includes the method for producing an optical material according to any one of <16> to <19>. <20>A cured product of two or more different monomers for optical materials, wherein at least one of the two or more different monomers for optical materials is an isocyanate compound, and there is no vein with a length of 1.0 mm or more within a range of 15 mm from the center of the cured product. A cured product in which the content of an amine measured by gas chromatography-mass spectrometry is more than 0% by mass and the content of an organic acid having a pKa value of less than 4 measured by gas chromatography-mass spectrometry is more than 0% by mass. <21>At least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, The cured product according to <20>, wherein the content of the amine is 0.001% by mass or more and 0.50% by mass or less, and the content of the organic acid having a pKa value of less than 4 is 0.001% by mass or more and 1% by mass or less. <22>At least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, The cured product according to <20>, wherein the content of the amine is 0.03% by mass or more and 2.5% by mass or less, and the content of the organic acid having a pKa value of less than 4 is 0.01% by mass or more and 5% by mass or less.

Advantages of the Invention

[0008] According to one embodiment of the present disclosure, there are provided a polymerizable composition and a polymerizable prepolymer composition that can shorten the production time of an optical material and are excellent in pot life. Further, according to one embodiment of the present disclosure, there are provided a method for producing an optical material using the polymerizable composition or the polymerizable prepolymer composition and a cured product.

Modes for Carrying Out the Invention

[0009] In the present disclosure, a numerical range represented by "~" means a range including the numerical values described before and after "~" as a lower limit value and an upper limit value. In the present disclosure, the amount of each component in the composition means the total amount of the plurality of substances present in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical ranges described in other step-by-step descriptions. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved.

[0010] ≪Polymerizable Composition for Optical Materials≫ The polymerizable composition for optical materials of the present disclosure contains two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, and at least one of the two or more different monomers for optical materials is an isocyanate compound, and the viscosity measured at 25 °C and 60 rpm with a B-type viscometer is 10 mPa·s to 1000 mPa·s. Hereinafter, the polymerizable composition for optical materials may also be simply referred to as "polymerizable composition".

[0011] The polymerizable composition of the present disclosure can shorten the production time of optical materials and has excellent pot life. Specifically, by using a basic polymerization catalyst as the polymerization catalyst and having a relatively large content thereof, the polymerization reaction during curing proceeds rapidly, and the production time of the optical material as a cured product is shortened. On the other hand, the viscosity of the polymerizable composition tends to increase after preparation, and the pot life tends to be short. The polymerizable composition of the present disclosure contains an organic acid having a pKa value of less than 4, so that the increase in viscosity after preparation is suppressed. The reason for this is considered to be that the organic acid having a pKa value of less than 4 forms a salt with the basic polymerization catalyst, thereby suppressing the activity of the basic polymerization catalyst. In the curing step of the polymerizable composition, it is considered that the salt formed by the organic acid having a pKa value of less than 4 and the basic polymerization catalyst dissociates by heat, and the activity of the basic polymerization catalyst is expressed, and the polymerization reaction proceeds rapidly. Furthermore, since the polymerizable composition having excellent pot life is excellent in injectability into a mold, a cured product having excellent optical properties (such as few veins) can be obtained.

[0012] (Monomer for optical material) The polymerizable composition contains two or more different monomers for optical materials, and at least one of the monomers for optical materials is an isocyanate compound.

[0013] The monomer for optical material is not particularly limited as long as it is a monomer used in the production of optical materials. For example, it may be a monomer used for producing an optical material having any of the following properties. The optical material obtained using the monomer for optical material may have a total light transmittance of 10% or more. The total light transmittance of the above optical material may be measured in accordance with JIS K 7361-1 (1997). The optical material obtained using the monomer for optical material may have a haze (i.e., total haze) of 10% or less, 1% or less, or 0.5% or less. The haze of the optical material is a value measured at 25 °C using a haze meter [(manufactured by Tokyo Denshoku Co., Ltd., TC-HIII DPK)] in accordance with JIS-K7105. The optical material obtained using the monomer for optical material has a refractive index of 1.56 or more, preferably 1.58 or more. The optical material obtained using the monomer for optical material may have a refractive index of 1.80 or less, or 1.75 or less. The refractive index of the optical material may be measured in accordance with JIS K7142 (2014).

[0014] The shape of the optical material obtained using the monomer for optical material is not particularly limited, and may be plate-like, columnar, cuboid, etc.

[0015] Examples of the monomer for an optical material include compounds having a property of polymerizing when a basic polymerization catalyst described later is used. Specifically, isocyanate compounds, polythiol compounds having two or more mercapto groups, hydroxy thiol compounds containing one or more mercapto groups and one or more hydroxyl groups, polyol compounds containing two or more hydroxyl groups, amine compounds, and the like can be mentioned.

[0016] The monomer for an optical material preferably contains an active hydrogen compound together with an isocyanate compound. The monomer for an optical material preferably contains at least one active hydrogen compound selected from the group consisting of a polythiol compound having two or more mercapto groups, a hydroxy thiol compound containing one or more mercapto groups and one or more hydroxyl groups, a polyol compound containing two or more hydroxyl groups, and an amine compound.

[0017] [Isocyanate compound] Examples of the isocyanate compound include aliphatic isocyanate compounds, alicyclic isocyanate compounds, aromatic isocyanate compounds, heterocyclic isocyanate compounds, and the like. These isocyanate compounds may contain dimers, trimers, and prepolymers. Examples of these isocyanate compounds include the compounds exemplified in International Publication No. 2011 / 055540. Furthermore, examples of the isocyanate compound include halogen-substituted products (for example, chlorine-substituted products, bromine-substituted products, etc.), alkyl-substituted products, alkoxy-substituted products, carbodiimide-modified products, urea-modified products, or burette-modified products of the above-mentioned compounds, Prepolymer type modified products of the above-mentioned compounds and nitro-substituted products, polyhydric alcohols, etc., Dimerization or trimerization reaction products of the above-mentioned compounds can also be used. These compounds may be used alone or in combination of two or more.

[0018] In the present disclosure, the aliphatic isocyanate compound refers to an isocyanate compound that does not contain an aromatic structure, an alicyclic structure, and a heterocyclic structure. An alicyclic isocyanate compound refers to an isocyanate compound that contains an alicyclic structure, does not contain an aromatic structure, and may contain a heterocyclic structure. An aromatic isocyanate compound refers to an isocyanate compound that contains an aromatic structure and may contain any one or a combination of an aliphatic structure, an alicyclic structure, and a heterocyclic structure. A heterocyclic isocyanate compound refers to an isocyanate compound that contains a heterocyclic structure and does not contain an alicyclic structure and an aromatic structure. In the present disclosure, a heterocyclic ring or a heterocyclic structure having aromaticity shall not correspond to an aromatic ring or an aromatic structure.

[0019] It is preferable that two or more different monomers for optical materials contain at least one selected from an aliphatic isocyanate compound, an alicyclic isocyanate compound, an aromatic isocyanate compound, and a heterocyclic isocyanate compound.

[0020] At least one of the monomers for optical materials may be an isocyanate compound having an aromatic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, etc., and a benzene ring is preferable. Specific examples of the isocyanate compound having an aromatic ring include aromatic isocyanate compounds. More specifically, isocyanate compounds in which an isocyanate group is directly bonded to the aromatic ring, isocyanate compounds in which an isocyanate group is bonded to the benzylic position of the aromatic ring, etc. can be mentioned. The isocyanate compound having an aromatic ring is preferable in that the activity of the isocyanate group is higher than that of the isocyanate compound having no aromatic ring, and the polymerization reaction is easily promoted.

[0021] At least one of the monomers for optical materials may be an isocyanate compound having no aromatic ring. Specific examples of the isocyanate compound having no aromatic ring include alicyclic isocyanate compounds having no aromatic ring, heterocyclic isocyanate compounds, and aliphatic isocyanate compounds. Isocyanate compounds without an aromatic ring are preferable in that the rate of the polymerization reaction is not too fast compared to isocyanate compounds having an aromatic ring, and the polymerization reaction is easy to control.

[0022] The monomer for an optical material may contain an isocyanate compound having an aromatic ring and an isocyanate compound without an aromatic ring. When the monomer for an optical material contains an isocyanate compound without an aromatic ring and an isocyanate compound having an aromatic ring, from the viewpoint of controlling the polymerization reaction, the ratio (A:B) of the isocyanate compound A without an aromatic ring to the isocyanate compound B having an aromatic ring is preferably in the range of 3:7 to 0:10, more preferably in the range of 2:8 to 0:10, in terms of the molar ratio of isocyanate groups.

[0023] When the monomer for an optical material contains an isocyanate compound without an aromatic ring and an isocyanate compound having an aromatic ring, it is preferable that the number of moles of isocyanate groups in the isocyanate compound without an aromatic ring is less than the number of moles of isocyanate groups in the isocyanate compound having an aromatic ring.

[0024] From the viewpoint of maintaining the quality of the optical material and shortening the production time of the optical material, the isocyanate compound preferably contains at least one selected from isophorone diisocyanate, 2,5-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, m-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, dicyclohexylmethane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,6-hexamethylene diisocyanate, and 1,5-pentamethylene diisocyanate. It is more preferable to contain at least one selected from isophorone diisocyanate, 2,5-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, m-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, dicyclohexylmethane diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane.

[0025] [[Active hydrogen compound]] Examples of the active hydrogen compound include polythiol compounds having two or more mercapto groups, hydroxy thiol compounds containing one or more mercapto groups and one or more hydroxyl groups, polyol compounds containing two or more hydroxyl groups, amine compounds, and the like. As the active hydrogen compound, oligomers of the above active hydrogen compounds or halogen-substituted products (for example, chlorine-substituted products, bromine-substituted products, etc.) of the above active hydrogen compounds may be used. The active hydrogen compound may be used alone or in combination of two or more.

[0026] (Polythiol compound having two or more mercapto groups) Examples of the polythiol compound having two or more mercapto groups include the compounds exemplified in International Publication No. 2016 / 125736. From the perspective of maintaining the quality of the optical material and shortening the manufacturing time of the optical material, the polythiol compound preferably contains at least one selected from 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, pentaerythritol tetrakis(3-mercaptopropionate), bis(mercaptoethyl) sulfide, pentaerythritol tetrakis(2-mercaptoacetate), 2,5-bis(mercaptomethyl)-1,4-dithiane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, and 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithietane. More preferably, it contains at least one selected from 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), and 2,5-bis(mercaptomethyl)-1,4-dithiane. Even more preferably, it contains at least one selected from 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and pentaerythritol tetrakis(3-mercaptopropionate).

[0027] (Polythiol compound having three or more mercapto groups) Examples of the active hydrogen compound also include polythiol compounds having three or more mercapto groups. When the polymerizable composition contains a polythiol compound having three or more mercapto groups as an active hydrogen compound, from the viewpoint of promoting the polymerization reaction, at least one of the three or more mercapto groups contained in the polythiol compound having three or more mercapto groups It is preferable to contain a compound in which a mercapto group is substituted with a group represented by the following formula (N1) (also referred to as compound (N1)).

[0028] [Chemical formula]

[0029] In formula (N1), * represents the bonding position.

[0030] When the polymerizable composition contains a polythiol compound having three or more mercapto groups as an active hydrogen compound, from the viewpoint of easy adjustment of the polymerization reaction, when measuring the peak area by high performance liquid chromatography, with respect to the peak area 100 of the polythiol compound having three or more mercapto groups, the peak area of compound (N1) is preferably 3.0 or less, and more preferably 1.5 or less. When measuring the peak area by high performance liquid chromatography, with respect to the peak area 100 of the polythiol compound having three or more mercapto groups, the peak area of compound (N1) is preferably 0.01 or more from the viewpoint of promoting the polymerization reaction. The peak area by high performance liquid chromatography can be measured by the method described in paragraph 0146 of International Publication No. 2014 / 027665 etc.

[0031] (Hydroxythiol compound containing one or more mercapto groups and one or more hydroxyl groups) Examples of the thiol compound having a hydroxy group include 2-mercaptoethanol, 3-mercapto-1,2-propanediol, glycerin bis(mercaptoacetate), 4-mercaptophenol, 2,3-dimercapto-1-propanol, pentaerythritol tris(3-mercaptopropionate), pentaerythritol tris(thioglycolate), and the like.

[0032] (Polyol compound containing two or more hydroxy groups) Examples of the polyol compound include one or more aliphatic or alicyclic alcohols. Specifically, linear or branched aliphatic alcohols, alicyclic alcohols, and alcohols obtained by adding at least one selected from the group consisting of ethylene oxide, propylene oxide, and ε-caprolactone to these alcohols can be mentioned. More specifically, the compounds exemplified in International Publication No. 2016 / 125736 can be mentioned.

[0033] The polyol compound is preferably at least one selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, and 1,4-cyclohexanediol.

[0034] (Amine compound) Examples of the amine compound include primary polyamine compounds such as ethylenediamine, 1,2- or 1,3-diaminopropane, 1,2-, 1,3- or 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, 1,2-, 1,3- or 1,4-diaminocyclohexane, o-, m- or p-diaminobenzene, 3,4- or 4,4'-diaminobenzophenone, 3,4- or 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3' or 4,4'-diaminodiphenyl sulfone, 2,7-diaminofluorene, 1,5-, 1,8- or 2,3-diaminonaphthalene, 2,3-, 2,6- or 3,4-diaminopyridine, 2,4- or 2,6-diaminotoluene, m- or p-xylylenediamine, isophoronediamine, diaminomethylbicycloheptane, 1,3- or 1,4-diaminomethylcyclohexane, 2- or 4-aminopiperidine, 2- or 4-aminomethylpiperidine, 2- or 4-aminoethylpiperidine, N-aminoethylmorpholine, N-aminopropylmorpholine; monofunctional secondary amine compounds such as diethylamine, dipropylamine, di-n-butylamine, di-sec-butylamine, diisobutylamine, di-n-pentylamine, di-3-pentylamine, dihexylamine, dioctylamine, di(2-ethylhexyl)amine, methylhexylamine, diallylamine, N-methylallylamine, piperidine, pyrrolidine, diphenylamine, N-methylamine, N-ethylamine, dibenzylamine, N-methylbenzylamine, N-ethylbenzylamine, dicyclohexylamine, N-methylaniline, N-ethylaniline, dinaphthylamine, 1-methylpiperazine, morpholine; Secondary polyamine compounds such as N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,2-diaminobutane, N,N'-dimethyl-1,3-diaminobutane, N,N'-dimethyl-1,4-diaminobutane, N,N'-dimethyl-1,5-diaminopentane, N,N'-dimethyl-1,6-diaminohexane, N,N'-dimethyl-1,7-diaminoheptane, N,N'-diethylethylenediamine, N,N'-diethyl-1,2-diaminopropane, N,N'-diethyl-1,3-diaminopropane, N,N'-diethyl-1,2-diaminobutane, N,N'-diethyl-1,3-diaminobutane, N,N'-diethyl-1,4-diaminobutane, N,N'-diethyl-1,5-diaminopentane, N,N'-diethyl-1,6-diaminohexane, N,N'-diethyl-1,7-diaminoheptane, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2,6-dimethylpiperazine, homopiperazine, 1,1-di-(4-piperidyl)methane, 1,2-di-(4-piperidyl)ethane, 1,3-di-(4-piperidyl)propane, 1,4-di-(4-piperidyl)butane, tetramethylguanidine; etc. are included.

[0035] Among the above, from the viewpoint of enhancing the heat resistance and refractive index of the cured product, the active hydrogen compound preferably contains a polythiol compound having two or more mercapto groups. The content of the polythiol compound having two or more mercapto groups is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more based on the total mass of the active hydrogen compound.

[0036] As the active hydrogen compound, the total content of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and pentaerythritol tetrakis(3-mercaptopropionate) is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more based on the total mass of the active hydrogen compound.

[0037] In the polymerizable composition, the molar ratio (NCO group / (OH group + SH group)) of the total of the hydroxyl group (OH group) and mercapto group (SH group) in the active hydrogen compound to the isocyanate group (NCO group) in the isocyanate compound is preferably 0.8 or more, more preferably 0.85 or more, and even more preferably 0.9 or more. In the polymerizable composition, the molar ratio (NCO group / (OH group + SH group)) of the total of the hydroxyl group (OH group) and mercapto group (SH group) in the active hydrogen compound to the isocyanate group (NCO group) in the isocyanate compound is preferably 1.2 or less, more preferably 1.15 or less, and even more preferably 1.1 or less.

[0038] When the polymerizable composition contains an isocyanate compound and an active hydrogen compound as monomers for an optical material, the total proportion of the isocyanate compound and the active hydrogen compound in the whole monomers for an optical material is preferably more than 70% by mass, more preferably 75% by mass or more, and even more preferably 80% by mass or more. The total proportion of the isocyanate compound and the active hydrogen compound in the whole monomers for an optical material may be 100% by mass, less than 100% by mass, 95% by mass or less, or 90% by mass or less.

[0039] <Basic polymerization catalyst> The coincidence composition contains at least one basic polymerization catalyst. Only one kind of basic polymerization catalyst may be used, or two or more kinds may be used in combination.

[0040] Examples of the basic polymerization catalyst include amine-based catalysts (including imidazole-based catalysts). Specific examples of the amine-based catalyst include triethylenediamine, N,N-dimethylethanolamine, triethylamine, N-ethylmorpholine, 2-methylpyrazine, pyridine, α-picoline, β-picoline, γ-picoline, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-propylpyridine, 2,4-lutidine, 3,4-lutidine, 2-methyl-5-ethylpyridine, 3,5-diethylpyridine, 2,3,5-collidine, 2,3-cyclopentenopyridine, 2,3-cyclohexenopyridine, 2,3-cycloheptenopyridine, 2-phenylpyridine, 4-phenylpyridine, 2-(4-methylphenyl)pyridine, 2,6-lutidine, 3,5-lutidine, 2,4,6-collidine, 3-chloropyridine, N,N-diethylaniline, N,N-dimethylaniline, hexamethylenetetramine, quinoline, isoquinoline, N,N-dimethyl-p-toluidine, N,N-dimethylpiperazine, quinazoline, 4-methylmorpholine, triallylamine, trioctylamine, 1-phenylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, etc.

[0041] As the basic polymerization catalyst, an amine-based catalyst is preferred. Preferred amine-based catalysts include tertiary amine-based catalysts such as 3,5-lutidine, 2,6-lutidine, 2,4,6-collidine, 2-ethylpyridine, 2,4-lutidine, 2-methyl-5-ethylpyridine, 2,3,5-collidine, triethylenediamine, N,N-dimethylethanolamine, triethylamine, N-ethylmorpholine, etc.

[0042] From the perspective of promoting the polymerization reaction during the curing process, the amine-based catalyst preferably contains at least one selected from 3,5-lutidine, 2,6-lutidine, 2,4,6-collidine, 2-ethylpyridine, 2,4-lutidine, 2-methyl-5-ethylpyridine, 2,3,5-collidine, triethylenediamine, and N-ethylmorpholine.

[0043] The basic polymerization catalyst preferably contains a compound represented by the following general formula (2) and / or a compound represented by the following general formula (3).

[0044]

Chemical formula

[0045] In general formula (2), R1 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a halogen atom, and a plurality of R1 may be the same or different. Q represents a carbon atom or a nitrogen atom. m represents an integer of 0 to 5.

[0046]

Chemical formula

[0047] In general formula (3), R2, R3, and R4 each independently represent a linear alkyl group having 3 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an allyl group, or a hydrocarbon group containing a hydroxyl group.

[0048] The pKa value of the basic polymerization catalyst is preferably 1 or more, more preferably 3 or more, and even more preferably 4 or more. The pKa value of the basic polymerization catalyst is preferably 9 or less, and more preferably 8 or less.

[0049] The pKa value (acid dissociation index) can be measured, for example, by the method described in (a) The Journal of Physical Chemistry vol.68, number6, page1560 (1964), the method using a potentiometric automatic titrator (such as AT-610 (trade name) etc.) manufactured by Kyoto Electronics Industry Co., Ltd., or the like. Alternatively, (c) the acid dissociation index described in the Chemical Handbook edited by the Chemical Society of Japan (revised 3rd edition, June 25, 1984, published by Maruzen Co., Ltd.) can be used as the pKa value of the basic polymerization catalyst.

[0050] The basic polymerization catalyst preferably contains at least one selected from basic polymerization catalysts having a pKa value of 4 to 8.

[0051] In the polymerizable composition of the present disclosure, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of two or more different monomers for optical materials is not particularly limited. For example, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of two or more different monomers for optical materials may be selected from the range of 0.010 parts by mass to 2.0 parts by mass. The polymerizable composition in which the content of the basic polymerization catalyst is within the above range contains a larger amount of the polymerization catalyst as compared with the polymerizable composition used in the conventional method for producing optical materials. As a result, when polymerizing the monomer for optical materials in the polymerizable composition in the curing step, the heat of reaction (i.e., the heat due to self-heating) of the polymerizable composition can be generated in a short time. As a result, the polymerization reaction can be promoted well. Furthermore, the heat convection, which is presumed to cause streaks due to the rapid increase in viscosity by the polymerization reaction of the polymerizable composition, is suppressed. As a result, a high-quality optical material can be obtained.

[0052] The content of the basic polymerization catalyst may be determined according to the type of the isocyanate compound contained in the polymerizable composition. For example, the content of the basic polymerization catalyst may be determined according to the presence or absence of an aromatic ring in the isocyanate compound.

[0053] When at least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably from 0.010 part by mass to 0.50 part by mass.

[0054] When the content of the basic polymerization catalyst used together with the isocyanate compound having an aromatic ring is 0.010 part by mass or more, the polymerization reaction can be promoted favorably, and a high-quality optical material can be obtained in a short time. Further, by promoting the polymerization reaction favorably, the mold release property when removing the cured product from the mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably 0.020 part by mass or more, and more preferably 0.030 part by mass or more.

[0055] When the content of the basic polymerization catalyst used together with the isocyanate compound having an aromatic ring is 0.50 part by mass or less, for example, the handleability when injecting the polymerizable composition into the mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably 0.20 part by mass or less, more preferably 0.10 part by mass or less, and still more preferably 0.09 part by mass or less.

[0056] When at least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably more than 0.05 part by mass and 2.0 parts by mass or less.

[0057] When the content of the basic polymerization catalyst used together with the isocyanate compound having no aromatic ring exceeds 0.05 parts by mass, the polymerization reaction can be promoted well, so that a high-quality optical material can be obtained in a short time. Further, by promoting the polymerization reaction well, the mold release property when removing the cured product from the mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of two or more different monomers for optical materials is preferably 0.08 parts by mass or more, preferably 0.10 parts by mass or more, more preferably 0.13 parts by mass or more, and still more preferably 0.15 parts by mass or more.

[0058] When the content of the basic polymerization catalyst used together with the isocyanate compound having no aromatic ring is 2.0 parts by mass or less, for example, the handleability when injecting the polymerizable composition into a mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of two or more different monomers for optical materials is preferably 1.8 parts by mass or less, more preferably 1.5 parts by mass or less, still more preferably 1.0 parts by mass or less, particularly preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less.

[0059] In the present disclosure, the content of the basic polymerization catalyst in the polymerizable composition can be appropriately set according to the type of the basic polymerization catalyst, the types and amounts of monomers (isocyanate compounds, active hydrogen compounds, other components, etc.) used, and the shape of the desired molded body.

[0060] When the polymerizable composition contains a prepolymer that is a polymer of monomers for optical materials, the content of the basic polymerization catalyst described above is the content with respect to 100 parts by mass of the monomers for optical materials including the raw materials of the prepolymer. The above-described range of the content of the basic polymerization catalyst may be appropriately changed depending on the types of the monomers for optical materials and the polymerization catalyst.

[0061] The basic polymerization catalyst preferably satisfies the following Condition 1. [Condition 1] -Ea / R is -7100 or more and -2900 or less. (Ea is the activation energy calculated by the Arrhenius plot from the reaction rate constants of the two or more different monomers for optical materials at two or more different temperatures, and R is the gas constant (8.314 J / mol / K).)

[0062] By the basic polymerization catalyst satisfying Condition 1, the variation in the polymerization rate of the polymerizable composition can be suppressed. As a result, the occurrence of optical distortion and vein patterns is suppressed, and an optical material with excellent appearance can be obtained.

[0063] The value of Ea is calculated by the following method. A physical property acquisition step of heating a composition 1 containing a polymerizable reactive compound and a predetermined amount of a polymerization catalyst, and acquiring the physical property value 1a derived from the functional group before heating of the polymerizable reactive compound and the physical property value 1b derived from the remaining functional group after holding at a plurality of temperatures; A remaining functional group rate calculation step of calculating the remaining functional group rate 1 at a plurality of the above temperatures from the physical property value 1a and the physical property value 1b; A reaction rate constant calculation step of calculating the reaction rate constant 1 at a plurality of the above temperatures from the remaining functional group rate 1 based on the reaction rate equation; A fitting step of calculating the activation energy Ea1 and the frequency factor A1 by the Arrhenius plot from the reaction rate constant 1 at a plurality of the above temperatures; By performing the above, the value of Ea is calculated. Using the calculated Ea, it is determined whether the polymerization catalyst satisfies Condition 1. The specific embodiments of the method for calculating the value of Ea and the method for determining whether the polymerization catalyst satisfies Condition 1 are the same as the specific embodiments described in International Publication No. 2020 / 256057.

[0064] <Organic acid with a pKa value of less than 4> The polymerizable composition of the present disclosure contains at least one organic acid having a pKa value of less than 4. Organic acids with a pKa value of less than 4 may be used alone or in combination of two or more.

[0065] The organic acid with a pKa value of less than 4 contained in the polymerizable composition forms a salt with the basic polymerization catalyst and suppresses the activity of the basic polymerization catalyst. Therefore, an increase in viscosity associated with the polymerization reaction of the monomer after the preparation of the polymerizable composition is suppressed, and the pot life is improved.

[0066] Specific examples of the organic acid with a pKa value of less than 4 include 10-camphorsulfonic acid (pKa: 1.2), methanesulfonic acid (pKa: -2.6), ethanesulfonic acid (pKa: 1.8), propanesulfonic acid (pKa: 1.9), butanesulfonic acid (pKa: 1.9), p-toluenesulfonic acid (pKa: -2.8), vinylsulfonic acid (pKa: -2.7), benzenesulfonic acid (pKa: 0.7), formic acid (pKa: 3.8), phthalic acid (pKa: 2.9), and the like. The organic acid may form a hydrate.

[0067] The content of the organic acid with a pKa value of less than 4 contained in the polymerizable composition may be, for example, 0.001 part by mass or more with respect to 100 parts by mass in total of two or more different monomers for optical materials. When the content of the organic acid with a pKa value of less than 4 with respect to 100 parts by mass in total of two or more different monomers for optical materials is 0.001 part by mass or more, an increase in viscosity of the polymerizable composition is effectively suppressed. From the above viewpoints, the content of the organic acid with a pKa value of less than 4 with respect to 100 parts by mass in total of two or more different monomers for optical materials is preferably 0.005 part by mass or more, and more preferably 0.01 part by mass or more.

[0068] The content of the organic acid with a pKa value of less than 4 contained in the polymerizable composition may be, for example, 1 part by mass or less with respect to 100 parts by mass in total of two or more different monomers for optical materials. When the content of an organic acid having a pKa value of less than 4 is 1 part by mass or less with respect to a total of 100 parts by mass of two or more different monomers for an optical material, in the curing step, dissociation of a salt formed by the organic acid and a basic polymerization catalyst due to heat is promoted, and the activity of the basic polymerization catalyst is likely to be exhibited. Thereby, the polymerization reaction can proceed rapidly. From the above viewpoints, the content of the organic acid having a pKa value of less than 4 is preferably 0.50 part by mass or less, more preferably 0.1 part by mass or less, with respect to a total of 100 parts by mass of two or more different monomers for an optical material.

[0069] When the polymerizable composition contains a prepolymer which is a polymer of a monomer for an optical material, the content of the organic acid having a pKa value of less than 4 described above is the content with respect to 100 parts by mass of the monomer for an optical material including the raw material of the prepolymer.

[0070] The molar ratio (X / Y) of the organic acid (X) having a pKa value of less than 4 to the basic polymerization catalyst (Y) is preferably 0.1 to 2.0, more preferably 0.15 to 1.25, and even more preferably 0.2 to 1.2.

[0071] From the viewpoint of favorably exhibiting the activity of the basic polymerization catalyst, the number of moles (x) of the functional groups of the organic acid having a pKa value of less than 4 in the polymerizable composition is preferably less than the number of moles (y) of the functional groups of the basic polymerization catalyst (the molar ratio represented by x / y is less than 1.0). That is, it is preferable that an excessive amount of the basic polymerization catalyst is present in the polymerizable composition with respect to the organic acid having a pKa value of less than 4.

[0072] (Other additives) The polymerizable composition may contain an arbitrary additive. Examples of the arbitrary additive include a photochromic compound, an internal release agent, a bluing agent, an ultraviolet absorber, and the like.

[0073] (Photochromic compound) A photochromic compound is a compound whose molecular structure changes reversibly upon irradiation with light of a specific wavelength, and whose light absorption characteristics (absorption spectrum) change accordingly. Examples of photochromic compounds include compounds whose light absorption characteristics (absorption spectrum) change with respect to light of a specific wavelength.

[0074] There are no particular restrictions on the photochromic compound, and any one can be appropriately selected and used from among conventionally known compounds that can be used for photochromic lenses. For example, one or more kinds can be used according to the desired coloring from among spiro pyran compounds, spiro oxazine compounds, fulgide compounds, naphtho pyran compounds, bis imidazole compounds, etc.

[0075] (Internal release agent) Examples of the internal release agent include acidic phosphoric esters. Examples of the acidic phosphoric esters include phosphoric acid monoesters and phosphoric acid diesters, and they can be used alone or in combination of two or more.

[0076] (Blueing agent) Examples of the blueing agent include those having an absorption band in the wavelength range from orange to yellow in the visible light region and having a function of adjusting the hue of an optical material made of resin. More specifically, the blueing agent includes substances showing blue to purple.

[0077] (Ultraviolet absorber) Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers such as 2,2'-dihydroxy-4-methoxybenzophenone, triazine-based ultraviolet absorbers such as 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, benzotriazole-based ultraviolet absorbers such as 2-(2H-benzotriazol-2-yl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-4-tert-octylphenol, and 2-(5-chloro-2H-benzotriazol-2-yl)-4-methyl-6-tert-butylphenol.

[0078] (Viscosity) From the viewpoint of suppressing the veins in the cured product, the viscosity of the polymerizable composition measured with a B-type viscometer under the conditions of 25°C and 60 rpm is 10 mPa·s or more, preferably 40 mPa·s or more, more preferably 70 mPa·s or more, still more preferably 80 mPa·s or more, particularly preferably 100 mPa·s or more, and even more preferably 120 mPa·s or more. From the viewpoint of maintaining good handleability when molding the optical material into a desired shape, the viscosity of the polymerizable composition measured with a B-type viscometer under the conditions of 25°C and 60 rpm is 1000 mPa·s or less, preferably 700 mPa·s or less, and more preferably 400 mPa·s or less.

[0079] The viscosity of the polymerizable composition may be adjusted according to the use of the resulting cured product. For example, when obtaining a cured product using a mold for a plus lens, since the runner (i.e., the injection port) is narrow (e.g., 1 mm to 3 mm), the viscosity of the polymerizable composition is preferably 10 mPa·s to 100 mPa·s from the viewpoint of suppressing the veins. On the other hand, when obtaining a cured product using a mold for a normal lens other than a plus lens, since the collar (i.e., the injection port) is wide (for example, 5 mm to 15 mm), from the viewpoint of suppressing streaks, the viscosity of the polymerizable composition is preferably 10 mPa·s to 1000 mPa·s, more preferably 100 mPa·s to 1000 mPa·s.

[0080] By increasing the viscosity of the polymerizable composition, when heat is applied from the outside, heat convection due to the temperature difference between the inside and the outside of the polymerizable composition can be suppressed, and streaks derived from heat convection can be reduced. If the amount of catalyst is small like in a conventional polymerizable composition, the thickening rate during polymerization is not sufficient, so the viscosity does not increase to a level where heat convection can be suppressed, and the temperature cannot be rapidly increased in a short time. Furthermore, the time required to complete the polymerization also becomes longer. On the other hand, considering the reactivity of the isocyanate compound having an aromatic ring as in the present disclosure and increasing the amount of catalyst within an optimal range, the viscosity of the entire above composition can be increased more rapidly. Thereby, heat convection due to a rapid temperature rise can be suppressed while suppressing uneven polymerization, and polymerization can proceed in a short time.

[0081] (Thickening rate) From the viewpoint of shortening the curing time of the polymerizable composition, the slope of the thickening rate of the polymerizable composition is preferably 0.005 or more, more preferably 0.007 or more, and even more preferably 0.01 or more. From the viewpoint of improving the pot life of the polymerizable composition, the slope of the thickening rate is preferably 0.04 or less, more preferably 0.035 or less, and even more preferably 0.03 or less.

[0082] The slope of the thickening rate of the polymerizable composition is defined as the value of b when the change in viscosity over time at 25°C is plotted with the horizontal axis (=X) being time (hr) and the vertical axis (=Y) being the viscosity of the polymerizable composition (mPa·S) and approximated by the following equation. a in the equation is the intercept. Y = a * exp(b * X) The viscosity X of the polymerizable composition in the above formula is measured with a B-type viscometer at 25°C and 60 rpm or 30 rpm. The time Y in the above formula is the elapsed time from the reference time (for example, when the polymerizable composition is prepared).

[0083] (Thixotropy ratio) The thixotropy ratio of the polymerizable composition is preferably 1.3 or less, more preferably 1.2 or less, and even more preferably 1.1 or less. When the thixotropy ratio of the polymerizable composition is 1.3 or less, it can be quickly filled into a polymerization container such as a mold, and heat convection during polymerization can be suppressed to effectively prevent the occurrence of streaks and the like. As a result, the quality of the obtained optical material can be kept good. The thixotropy ratio of the polymerizable composition is preferably 0.9 or more, more preferably 0.95 or more, and even more preferably 1.0 or more.

[0084] The thixotropy ratio of the polymerizable composition is calculated by dividing the viscosity η1 measured at 25°C and a rotational speed of 6 rpm with a B-type viscometer by the viscosity η2 measured at a rotational speed of 60 rpm.

[0085] The thixotropy ratio of the polymerizable composition can be decreased, for example, by decreasing the molecular weights of two or more different monomers for optical materials, suppressing the degree of polymerization of the prepolymer to a certain level or less, or decreasing the ratio of the structure that gives elasticity in the monomer.

[0086] The polymerizable composition is preferably a polymer of two or more different monomers for optical materials and further contains a prepolymer having polymerizable functional groups. In the present disclosure, the prepolymer means a polymer that is a polymer of two or more different monomers for optical materials and has polymerizable functional groups. A cured product obtained by polymerizing a prepolymer and two or more different monomers for optical materials can be used as an optical material. Examples of the prepolymer include a polymer obtained by polymerizing two types of monomers for optical materials among monomers for optical materials at an equivalent ratio of 1:1, a polymer obtained by polymerizing two types of monomers for optical materials among monomers for optical materials at an unbalanced equivalent ratio, and the like. In the present disclosure, the polymerizable functional group means a functional group capable of polymerizing with other polymerizable functional groups. Specific examples of the polymerizable functional group include functional groups having active hydrogen such as an isocyanate group and a mercapto group described later. In the present disclosure, polymerizing at an equivalent ratio of 1:1 means, for example, when polymerizing using an isocyanate compound and a polythiol compound, polymerizing at an amount such that the molar ratio of the isocyanate group of the isocyanate compound and the mercapto group of the polythiol compound is 1:1.

[0087] ≪Polymerizable prepolymer composition for optical material≫ The polymerizable prepolymer composition for optical material of the present disclosure is a polymer of two or more different monomers for optical materials and includes a prepolymer having a polymerizable functional group, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4. At least one of the two or more different monomers for optical materials is an isocyanate compound, and the viscosity measured at 25°C and 60 rpm with a B-type viscometer is 10 mPa·s to 2000 mPa·s. Hereinafter, the polymerizable prepolymer composition for optical material is also simply referred to as "polymerizable prepolymer composition". The polymerizable prepolymer composition of the present disclosure can shorten the production time of optical materials and has excellent pot life.

[0088] Specific examples, preferred specific examples, preferred embodiments, etc. of the monomer for optical material, the basic polymerization catalyst, and the organic acid having a pKa value of less than 4 in the polymerizable prepolymer composition are the same as those of the monomer for optical material, the basic polymerization catalyst, and the organic acid having a pKa value of less than 4 described in the section of the polymerizable composition for optical material above. The definition of the prepolymer in the coincident prepolymer composition is the same as the definition of the prepolymer described in the section of the polymerizable composition above. Specific examples, preferred specific examples, preferred embodiments, etc. of physical properties such as the viscosity of the polymerizable prepolymer composition are the same as those of the physical properties, specific examples, preferred specific examples, preferred embodiments, etc. described in the section of the polymerizable composition for optical materials above.

[0089] In the polymerizable prepolymer composition of the present disclosure, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of two or more different monomers for optical materials is not particularly limited. For example, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of two or more different monomers for optical materials may be selected from the range of 0.002 parts by mass to 4.0 parts by mass.

[0090] The content of the basic polymerization catalyst may be determined according to the type of the isocyanate compound contained in the polymerizable prepolymer composition. For example, the content of the basic polymerization catalyst may be determined according to the presence or absence of an aromatic ring in the isocyanate compound.

[0091] When at least one of two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, the content of the basic polymerization catalyst contained in the polymerizable prepolymer composition is preferably 0.002 parts by mass to 1 part by mass with respect to a total of 100 parts by mass of two or more different monomers for optical materials.

[0092] Since the content of the basic polymerization catalyst used together with the isocyanate compound having an aromatic ring is 0.002 parts by mass or more, the polymerization reaction can be promoted well, so that a high-quality optical material can be obtained in a short time. Further, by promoting the polymerization reaction well, the mold release property when removing the cured product from the mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of two or more different monomers for optical materials is preferably 0.010 parts by mass or more, more preferably 0.050 parts by mass or more, and even more preferably 0.070 parts by mass or more.

[0093] By having the content of the basic polymerization catalyst used together with the isocyanate compound having an aromatic ring be 1 part by mass or less, for example, the handleability when injecting the polymerizable prepolymer composition into a mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably 0.50 part by mass or less, more preferably 0.15 part by mass or less, and even more preferably 0.10 part by mass or less.

[0094] When at least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, the content of the basic polymerization catalyst contained in the polymerizable prepolymer composition is preferably 0.1 part by mass to 4.0 parts by mass with respect to 100 parts by mass in total of the two or more different monomers for optical materials.

[0095] By having the content of the basic polymerization catalyst used together with the isocyanate compound having no aromatic ring be 0.1 part by mass or more, the polymerization reaction can be promoted well, so that a high-quality optical material can be obtained in a short time. Also, by promoting the polymerization reaction well, the mold release property when removing the cured product from the mold can be improved. From the above viewpoints, the content of the polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably 0.15 part by mass or more, and more preferably 0.20 part by mass or more.

[0096] By having the content of the basic polymerization catalyst used together with the isocyanate compound having no aromatic ring be 4.0 parts by mass or less, for example, the handleability when injecting the polymerizable prepolymer composition into a mold can be improved. From the above viewpoints, the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the two or more different monomers for optical materials is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, and even more preferably 1.0 parts by mass or less.

[0097] (Viscosity) From the viewpoint of suppressing the texture in the cured product, the viscosity of the polymerizable prepolymer composition measured with a B-type viscometer under the conditions of 25°C and 60 rpm is 10 mPa·s or more, preferably 40 mPa·s or more, more preferably 70 mPa·s or more, still more preferably 80 mPa·s or more, particularly preferably 100 mPa·s or more, and even more preferably 120 mPa·s or more. The method for measuring the viscosity of the polymerizable prepolymer composition is as described above.

[0098] (Rate of viscosity increase) From the viewpoint of shortening the curing time of the polymerizable prepolymer composition, the slope of the rate of viscosity increase of the polymerizable prepolymer composition is preferably 0.005 or more, more preferably 0.007 or more, and still more preferably 0.01 or more. From the viewpoint of improving the pot life of the polymerizable prepolymer composition, the slope of the rate of viscosity increase is preferably 0.04 or less, more preferably 0.035 or less, and still more preferably 0.03 or less. The method for measuring the slope of the rate of viscosity increase of the polymerizable prepolymer composition is as described above.

[0099] (Thixotropy ratio) The polymerizable prepolymer composition preferably has a thixotropy ratio of 1.3 or less, more preferably 1.2 or less, and still more preferably 1.1 or less. When the thixotropy ratio of the polymerizable prepolymer composition is 1.3 or less, the polymerizable prepolymer composition can be quickly filled into a polymerization container such as a mold, and heat convection during polymerization can be suppressed to further prevent the occurrence of texture and the like. As a result, the occurrence of texture and the like in the obtained optical material can be suppressed, and the quality can be kept good. The thixotropy ratio of the polymerizable prepolymer composition is preferably 0.9 or more, more preferably 0.95 or more, and still more preferably 1.0 or more. The method for measuring the thixotropy ratio is as described above.

[0100] From the perspective of handleability, the prepolymer may preferably contain isocyanate groups in the polymerizable prepolymer composition. That is, it is preferable that not all of the isocyanate groups possessed by the prepolymer are polymerized, but only a part thereof is polymerized, and it is preferable that 70% or more of the isocyanate groups possessed by the isocyanate compound used in the production of the polymerizable prepolymer composition remain unpolymerized. When the prepolymer contains isocyanate groups, that is, when it contains more than other monomers for optical materials that can polymerize with the isocyanate compound, the viscosity of the polymerizable prepolymer composition can be kept low when the viscosity of the other monomers for optical materials is high, and handling becomes easy. In particular, when the above-mentioned other monomers for optical materials include one or more selected from the group consisting of 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and pentaerythritol tetrakis(3-mercaptopropionate), it is preferable that the prepolymer contains isocyanate groups from the perspective of handleability.

[0101] It is also preferable that the polymerizable prepolymer composition substantially does not contain isocyanate groups in the prepolymer. In the present disclosure, "the prepolymer substantially does not contain isocyanate groups" means a state in which almost all of the isocyanate groups are polymerized. Specifically, "the prepolymer substantially does not contain isocyanate groups" means that the content of isocyanate groups in the prepolymer is below the detection limit when measured with an IR spectrometer. When the prepolymer substantially does not contain isocyanate groups, since substantially no highly reactive isocyanate groups exist, the stability of the polymerizable prepolymer composition can be improved.

[0102] The refractive index difference (also referred to as "refractive index A - refractive index B") obtained by subtracting the refractive index B of the prepolymer raw material composition, which is the composition before forming the prepolymer and contains two or more different monomers for optical materials and a polymerization catalyst, from the refractive index A of the polymerizable prepolymer composition is preferably greater than 0, more preferably 0.005 or more, and even more preferably 0.01 or more. The refractive index A is the refractive index of the polymerizable prepolymer composition after polymerizing the monomers for optical materials and the polymerization catalyst to obtain a prepolymer, and the refractive index B is the refractive index of the prepolymer raw material composition before polymerizing the monomers for optical materials and the polymerization catalyst to obtain a prepolymer.

[0103] When the refractive index A - refractive index B is within the above range, it becomes easy to adjust the viscosity of the polymerizable prepolymer composition to a predetermined range. Also, it becomes easy to stabilize the quality (refractive index, appearance, etc.) of the cured product of the polymerizable prepolymer composition. The refractive index A - refractive index B may be 0.04 or less, or may be 0.03 or less. When the prepolymer contains isocyanate groups, the refractive index A - refractive index B is preferably 0.005 or more, more preferably 0.010 or more. Also, the refractive index A - refractive index B is preferably 0.040 or less, more preferably 0.030 or less. When the prepolymer substantially does not contain isocyanate groups, the refractive index A - refractive index B is preferably 0.005 or more, more preferably 0.010 or more. Also, the refractive index A - refractive index B is preferably 0.035 or less, more preferably 0.025 or less.

[0104] The polymerizable prepolymer composition preferably has a viscosity that does not easily change over time (i.e., is stable). The stability of the viscosity of the polymerizable prepolymer composition means that when the polymerizable prepolymer composition is stored at 20°C for 24 hours, the change in viscosity before and after storage is 10% or less. Examples of the polymerizable prepolymer composition with stable viscosity include a polymerizable prepolymer composition that does not contain a polymerizable functional group that easily undergoes a polymerization reaction with the polymerizable functional group contained in the prepolymer.

[0105] ≪Cured product≫ The cured product of the present disclosure is a cured product of the above-described polymerizable composition or polymerizable prepolymer composition.

[0106] The cured product of the present disclosure may contain an amine as a component derived from the polymerizable composition or polymerizable prepolymer composition. For example, a cured product of a polymerizable composition or polymerizable prepolymer composition containing an amine-based catalyst as a basic polymerization catalyst may contain an amine. The content of the amine contained in the cured product is not particularly limited, and may be, for example, more than 0% by mass and 1% by mass or less.

[0107] When the polymerizable composition or polymerizable prepolymer composition contains an isocyanate compound having an aromatic ring as a monomer for an optical material and contains an amine-based catalyst as a basic polymerization catalyst, from the viewpoint of reducing the veining in the cured product, the content of the amine in the cured product is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more. From the viewpoint of improving the handleability of the polymerizable composition, the content of the amine in the cured product is preferably 0.50% by mass or less, more preferably 0.20% by mass or less, and even more preferably 0.10% by mass or less.

[0108] When the polymerizable composition or polymerizable prepolymer composition contains an isocyanate compound having no aromatic ring as a monomer for an optical material and contains an amine-based catalyst as a basic polymerization catalyst, from the viewpoint of reducing the veining in the cured product, the content of the amine in the cured product is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.07% by mass or more. From the viewpoint of improving the handleability of the coincidence composition, the content of amine in the cured product is preferably 2.5% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less.

[0109] In the present disclosure, the content of amine in the cured product is the content of amine measured by gas chromatography-mass spectrometry from the dichloromethane composition obtained by dispersing the cured product in dichloromethane and performing ultrasonic extraction. The method for measuring the content of amine in the cured product is as follows. Put 200 mg of the cured product powdered with a metal file and 3 mL of dichloromethane into a centrifuge tube (volume 10 mL), perform ultrasonic extraction at room temperature for 10 minutes using an ultrasonic cleaner (manufactured by IUCHI, US-4), and perform centrifugation at 4000 rpm for 10 minutes using a centrifuge (manufactured by KUBOTA, tabletop small centrifuge 2410). Collect the supernatant, disperse the residue again in 3 mL of dichloromethane, perform the above ultrasonic extraction and centrifugation, and collect the supernatant (hereinafter also referred to as "residue extraction"). After performing the above residue extraction two more times, add dichloromethane to the obtained supernatant so that the total amount becomes 10 mL. Filter the obtained 10 mL supernatant, analyze it by gas chromatography-mass spectrometry (also referred to as GC-MS) (GC-MS device: manufactured by Agilent, 6890GC / 5973N MSD, column: CP-Sil 8 CB for Amine (0.25 mm ID × 30 m F.T = 0.25 μm)) to obtain the peak area value derived from amine. Prepare a calibration curve of the obtained peak area value derived from amine and the amount of amine, and measure the content of amine in the cured product.

[0110] Note that the above amine means an amine compound contained as a basic polymerization catalyst, an active hydrogen compound, etc. in the polymerizable composition or the polymerizable prepolymer composition.

[0111] The cured product of the present disclosure may contain an organic acid having a pKa value of less than 4 as a component derived from the polymerizable composition or the polymerizable prepolymer composition. The content of the organic acid having a pKa value of less than 4 contained in the cured product is not particularly limited, and may be, for example, more than 0% by mass and 1% by mass or less.

[0112] When the polymerizable composition or the polymerizable prepolymer composition contains an isocyanate compound having an aromatic ring as a monomer for an optical material, from the viewpoint of improving the pot life of the polymerizable composition or the polymerizable prepolymer composition and reducing the veins in the cured product, the content of the organic acid having a pKa value of less than 4 in the cured product is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more. From the viewpoint of shortening the curing time of the polymerizable composition, the content of the organic acid having a pKa value of less than 4 in the cured product is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.

[0113] When the polymerizable composition or the polymerizable prepolymer composition contains an isocyanate compound having no aromatic ring as a monomer for an optical material, from the viewpoint of improving the pot life of the polymerizable composition or the polymerizable prepolymer composition and reducing the veins in the cured product, the content of the organic acid having a pKa value of less than 4 in the cured product is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.03% by mass or more. From the viewpoint of shortening the curing time of the polymerizable composition, the content of the organic acid having a pKa value of less than 4 in the cured product is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0114] In the present disclosure, the content of the organic acid having a pKa value of less than 4 in the cured product is measured in the same manner as the content of the above-described amine.

[0115] Particularly in optical applications where light transmissivity is required, the devitrification degree of the cured product is preferably less than 50, and more preferably less than 35. The devitrification degree of the cured product is measured by the following method. For the cured product, transmit light from a light source (for example, Luminar Ace LA-150A manufactured by Hayashi Repic) in a dark place. Capture the image of the light transmitted through the cured product into an image processing device (for example, an image processing device manufactured by Ube Information Systems), and perform shading processing on the captured image. Quantify the degree of shading of the processed image for each pixel, and define the value calculated as the average value of the numerical values of the degree of shading of each pixel as the opacity.

[0116] It is preferable that the cured product has no veins with a length of 1.0 mm or more within a range of 15 mm in radius from the center of the cured product, and it is more preferable that there are no veins with a length of 1.0 mm or more within and outside the range of 15 mm in radius from the center of the cured product.

[0117] More specifically, the cured product is a cured product of two or more different optical monomers, at least one of the two or more different optical material monomers is an isocyanate compound, there are no veins with a length of 1.0 mm or more within a range of 15 mm in radius from the center of the cured product, the content of amine measured by gas chromatography-mass spectrometry is more than 0% by mass, and the content of an organic acid with a pKa value of less than 4 measured by gas chromatography-mass spectrometry is more than 0% by mass. The cured product may also be such that the content of amine measured by gas chromatography-mass spectrometry may be 1% by mass or less, and the content of an organic acid with a pKa value of less than 4 measured by gas chromatography-mass spectrometry may be 1% by mass or less. The content of amine measured by gas chromatography-mass spectrometry may be 1% by mass or less, and the content of an organic acid with a pKa value of less than 4 measured by gas chromatography-mass spectrometry may be 1% by mass or less. The preferable range of the content of amine or an organic acid with a pKa value of less than 4 contained in the cured product is as described above.

[0118] The details and preferable embodiments of two or more different optical material monomers and an isocyanate compound having an aromatic ring are as described above.

[0119] In the cured product of the present disclosure, two or more different optical material monomers may include an isocyanate compound having an aromatic ring and an isocyanate compound not having an aromatic ring. When two or more different monomers for optical materials contain an isocyanate compound having no aromatic ring and an isocyanate compound having an aromatic ring, from the viewpoint of controlling the polymerization reaction, the ratio of the isocyanate compound having no aromatic ring to the isocyanate compound having an aromatic ring is preferably in the range of 3:7 to 0:10 and more preferably in the range of 2:8 to 0:10 in terms of the molar ratio of isocyanate groups.

[0120] ≪Manufacturing Method of Optical Material≫ The manufacturing method of the optical material of the present disclosure includes the following manufacturing methods A and B.

[0121] <Manufacturing Method A> Manufacturing method A includes a preparation step of preparing a polymerizable composition containing two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein at least one of the two or more different monomers for optical materials is an isocyanate compound; a casting step of adjusting the viscosity of the polymerizable composition measured at 25°C and 60 rpm with a B-type viscometer to 10 mPa·s to 1000 mPa·s and casting the polymerizable composition for optical materials into a mold; and a curing step of curing the polymerizable composition by polymerizing the two or more different monomers for optical materials in the polymerizable composition in the mold.

[0122] By including the above preparation step, the above casting step, and the above curing step, manufacturing method A can maintain the quality of the obtained optical material and shorten the manufacturing time of the optical material.

[0123] Manufacturing method A may include the above preparation step, the above casting step, and the above curing step in this order.

[0124] In the polymerizable composition prepared in the preparation step, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of two or more different monomers for optical materials is not particularly limited. For example, the content of the basic polymerization catalyst may be 0.010 parts by mass to 2.0 parts by mass with respect to a total of 100 parts by mass of two or more different monomers for optical materials. The polymerizable composition with the basic polymerization catalyst content within the above range contains a large amount of basic polymerizable catalyst as compared with the conventional manufacturing methods of optical materials. Thereby, when polymerizing the monomer for the optical material in the polymerizable composition in the curing step, the heat of reaction (i.e., the heat due to self-heating) of the polymerizable composition can be generated in a short time. Since the polymerization reaction of the monomer for the optical material in the polymerizable composition can be promoted by utilizing the above heat of reaction, a high-quality optical material can be obtained in a shorter time than before. In the conventional method, the polymerization reaction was mainly generated by heating the polymerizable composition. However, in Production Method A, heating of the polymerizable composition is not necessarily required. Moreover, since Production Method A also utilizes the self-heating of the polymerizable composition, the polymerization can proceed without excessively depending on the supply of heat from the outside. Therefore, in combination with increasing the viscosity of the polymerizable composition described later, the non-uniformity of heat and heat convection in the polymerizable composition can be suppressed, and the generation of streaks can be suppressed. In the present disclosure, streaks refer to a state where the refractive index of a specific portion is different from the normal refractive index of the surroundings. It can also be expressed as a state that causes disadvantages in the desired use of the optical material. In an optical material, streaks are a type of defect.

[0125] The content of the basic polymerization catalyst contained in the polymerizable composition may be determined according to the type of the isocyanate compound contained in the polymerizable composition. For example, the content of the basic polymerization catalyst may be determined according to the presence or absence of an aromatic ring in the isocyanate compound.

[0126] The preferable range of the content of the basic polymerization catalyst contained in the polymerizable composition is the same as the preferable range of the content of the basic polymerization catalyst contained in the above-described polymerizable composition.

[0127] <Preparation Step> Production method A includes a preparation step of preparing a polymerizable composition containing two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein at least one of the two or more different monomers for optical materials is an isocyanate compound. The preparation step may be simply a step of preparing a pre-produced polymerizable composition, or may be a step of producing a polymerizable composition.

[0128] In the preparation step, the polymerizable composition is not particularly limited as long as it contains two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4. As the polymerizable composition, a ready-made product may be used, or at least two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4 may be mixed and prepared. The mixing method is not particularly limited, and known methods can be applied.

[0129] The temperature when mixing each component of the polymerizable composition is not particularly limited, but it is preferably 30°C or lower, and more preferably room temperature (25°C) or lower. From the perspective of the pot life of the polymerizable composition, it may be preferable to make the temperature even lower than 25°C. When the solubility of additives such as internal release agents and the above components is not good, the above components may be heated in advance to dissolve the above additives in the above components.

[0130] When mixing the above components, it is preferably carried out under a dry inert gas to prevent moisture from entering the polymerizable composition.

[0131] The preparation step is preferably a step of pre-mixing a basic polymerization catalyst and an organic acid having a pKa value of less than 4 in a part of the two or more different monomers for optical materials, and then mixing the remaining part of the two or more different monomers for optical materials to produce a polymerizable composition. In this case, until the mixture containing a part of monomers for two or more different optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4 is mixed with the mixture containing no basic polymerization catalyst and no organic acid having a pKa value of less than 4 and containing the remainder of the two or more different monomers for optical materials, polymerization between a part of the two or more different monomers for optical materials and the remainder of the two or more different monomers for optical materials can be prevented from occurring. Therefore, by performing the preparation steps in the above order, the start timing of polymerization can be adjusted. Therefore, for example, the handleability when injecting the polymerizable composition into a mold can be improved. The mixing of the remainder of the two or more different monomers for optical materials with the mixture of a part of the two or more different monomers for optical materials, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4 may be carried out in a single time or may be carried out in multiple times. Specific embodiments of the preparation step include, for example, the following embodiments.

[0132] First, a part of the monomer for the optical material and an additive (for example, an internal mold release agent) are charged and mixed to prepare a mixed solution. After this mixed solution is stirred at 25°C for 1 hour to completely dissolve each component, a part of the remainder of the monomer for the optical material is further charged and stirred to obtain a uniform solution. Defoaming is performed on this solution to obtain a first mixed solution. Next, the remainder of the monomer for the optical material, the basic polymerization catalyst, and the organic acid having a pKa value of less than 4 are stirred at 25°C for 30 minutes to completely dissolve them, and a second mixed solution is obtained. Then, the first mixed solution and the second mixed solution are mixed to obtain a polymerizable composition.

[0133] <Casting step> Production method A includes a casting step of adjusting the viscosity of the polymerizable composition measured with a B-type viscometer at 25°C and 60 rpm to 10 mPa·s to 1000 mPa·s and casting it into a mold. By adjusting the viscosity of the polymerizable composition within the above range and casting it, the veins in the obtained optical material can be effectively suppressed.

[0134] From the above viewpoints, the viscosity of the polymerizable composition is 10 mPa·s or more, preferably 40 mPa·s or more, more preferably 70 mPa·s or more, still more preferably 80 mPa·s or more, particularly preferably 100 mPa·s or more, and even more preferably 120 mPa·s or more. From the viewpoint of maintaining good handleability when molding the optical material into a desired shape, the viscosity of the polymerizable composition is 1000 mPa·s or less, preferably 700 mPa·s or less, and more preferably 400 mPa·s or less.

[0135] There is no particular limitation on the method for adjusting the viscosity of the polymerizable composition. For example, the viscosity of the polymerizable composition may be adjusted by methods such as adding a high-viscosity compound, heating, and stirring.

[0136] <Curing step> Production method A includes a curing step of curing the polymerizable composition by polymerizing the two or more different monomers for optical materials in the polymerizable composition in the mold. By including a curing step, production method A can polymerize the polymerizable composition and produce an optical material. In the conventional method, the polymerizable composition was heated to cause a polymerization reaction. However, in production method A, the polymerizable composition can promote the polymerization reaction of the monomers for optical materials in the polymerizable composition by increasing the heat of reaction (i.e., heat due to self-heating) associated with the polymerization reaction. That is, in the curing step of production method A, the polymerizable composition can be cured by allowing the polymerizable composition to stand still. Therefore, in production method A, heating of the polymerizable composition is not necessarily required, but the polymerizable composition may be heated to promote the polymerization reaction.

[0137] The environment in which the curing process is carried out is not particularly limited, and it can be cured by heating from outside the mold. However, from the perspective of enhancing optical quality such as texture and polymerizing in a short time, it is preferable that the polymerizable composition is cured by being left standing in a closed space. By leaving the polymerizable composition standing in a closed space, the heat generated by the self-heating of the polymerizable composition can be prevented from being released to the outside. As a result, the heat generated by self-heating can be retained in the closed space. As a result, the polymerization reaction can be promoted more efficiently, and an optical material can be manufactured in a shorter time. Examples of the closed space include a heat-insulated environment. The heat-insulated environment refers to an environment that retains heat inside and suppresses heat conduction between the inside and the outside. The environment in which heat conduction between the inside and the outside is suppressed means an environment in which the heat conductivity between the inside and the outside of the closed space is at a level that can cure the polymerizable composition when the polymerizable composition is left standing in the closed space.

[0138] The heat-insulated environment can be formed using, for example, a heat-insulating material. That is, by leaving the polymerizable composition standing in a heat-insulating container made of a heat-insulating material, heat can be retained inside the heat-insulating container, and heat conduction between the inside and the outside can be suppressed.

[0139] The thermal conductivity of the heat-insulating material is preferably 0.50 W / mK or less, more preferably 0.10 W / mK or less, and even more preferably 0.05 W / mK or less.

[0140] The density of the heat-insulating material is preferably 10 kg / m 3 or more, more preferably 15 kg / m 3 or more, and even more preferably 20 kg / m 3 or more.

[0141] In the "heat insulation" or "heat-insulated environment" in Production Method A, heating is preferably performed to keep the heat-insulated reaction tank in a constant temperature state (constant temperature reaction tank) within a range that does not prevent the polymerization reaction due to the heat of reaction of the polymerizable composition or overly accelerate the polymerization reaction of the polymerizable composition by external heating. Thereby, according to the temperature rise state or the like due to the self-heating of the monomer for optical materials, the environment in the reaction tank where the mold is placed can be kept in a heat-insulated state or a constant temperature state, so that the polymerization reaction can be promoted better.

[0142] As the heat-insulated environment, for example, the above-described heat-insulated reaction tank or constant temperature reaction tank can be used. For example, when the mold into which the monomer is injected is left still in a vacuum container that is a heat-insulated reaction tank, the heat-insulated polymerization in the heat-insulated environment using the heat-insulated reaction tank (constant temperature reaction tank) can be carried out according to the following procedure. Cover the inner surface of the vacuum container with a member having heat-insulating and heat-retaining properties such as urethane foam and cork, and wrap the mold into which the monomer is injected with a member such as a cloth as needed. Then, the mold into which the monomer is injected is left still in the vacuum container.

[0143] The curing step may be a step of curing the polymerizable composition by leaving the polymerizable composition still without heating it from the outside. As described above, in Production Method A, heating of the polymerizable composition is not necessarily required. In order to heat from the outside, a device may be used, and the economic burden may increase. In the case of Production Method A, since an optical material can be produced by a simple method, the economic burden can be reduced.

[0144] The curing step is preferably a step of curing the polymerizable composition by leaving the polymerizable composition still for 2 to 10 hours. According to the conventional method, generally, the polymerization reaction is carried out over several hours to several tens of hours (for example, about 20 to 48 hours) while gradually increasing the temperature by heating. When the time for performing the polymerization reaction is short, the polymerizable composition may not cure completely, resulting in the inability to obtain an optical material or a deterioration in the quality of the optical material. However, according to Production Method A, an optical material can be produced in a short time while maintaining the quality of the obtained optical material. Specifically, the optical material can be produced by allowing the polymerizable composition to stand for 10 hours or less. From the above viewpoints, in the curing step, it is more preferable to allow the polymerizable composition to stand for 8 hours or less. Also, from the viewpoint of performing the polymerization reaction to obtain a well-cured optical material, it is preferable to allow the polymerizable composition to stand for 2 hours or more, and more preferably 5 hours or more.

[0145] In the curing step, if necessary, a microwave irradiation step of irradiating the polymerizable composition with microwaves for a predetermined time may be provided.

[0146] One embodiment of the curing step includes the following steps a and b. Step a: Inject (cast) the polymerizable composition into a mold (inside the cavity of the mold). Step b: Allow the mold filled with the polymerizable composition to stand in a closed space for a predetermined time for adiabatic polymerization.

[0147] (Step a) First, inject the polymerizable composition into a molding mold (mold) held by a gasket or tape, etc. At this time, depending on the physical properties required for the obtained optical material, it is preferable to perform a defoaming treatment under reduced pressure and / or a filtration treatment under pressure or reduced pressure, etc., if necessary.

[0148] (Step b) The polymerization conditions are not limited, but it is preferable to appropriately adjust them according to the composition of the polymerizable composition, the type and amount of the catalyst used, the shape of the mold, etc. The mold filled with the polymerizable composition may be allowed to stand in an adiabatic environment for 2 to 4 hours for polymerization.

[0149] In Process b, after the heat insulation polymerization process of allowing the mold injected with the polymerizable composition to stand in a heat insulation environment for a certain period of time as needed, a heating step may be added. In Process b, parallel to the step of allowing the mold injected with the polymerizable composition to stand (heat insulation polymerization) in a heat insulation environment as needed, continuously or intermittently, the mold injected with the polymerizable composition may be heated at a temperature not exceeding the self-heating generated by the polymerizable composition in the heat insulation polymerization process, or the inside of the heat insulation reaction tank may be heated to keep the environmental temperature inside the heat insulation reaction tank constant.

[0150] <Annealing step> Production Method A may include an annealing step of annealing the cured polymerizable composition as needed. The temperature at which the annealing treatment is performed is usually 50 to 150 °C, preferably 90 to 140 °C, and more preferably 100 to 130 °C.

[0151] <Other steps> Production Method A may be provided with other steps as needed. Examples of other steps include an injection step of injecting the polymerizable composition into the mold when producing an optical material using the mold.

[0152] <Use of optical material> The optical material in Production Method A can be used for plastic lenses, prisms, optical fibers, information recording substrates, filters, light-emitting diodes, etc. Among the above, the optical material in the embodiments of the present disclosure can be preferably used for plastic lenses, and more preferably used for plastic lenses for glasses.

[0153] <Production Method B> Production Method B includes a preparation step of preparing two or more different monomers for optical materials and a basic polymerization catalyst, Mix a part of the monomers for the two or more different optical materials and at least a part of the basic polymerization catalyst, and polymerize at least a part of the part of the monomers for the two or more different optical materials to obtain a prepolymer, thereby obtaining a mixture containing the prepolymer, which is a prepolymerization step. An acid addition step of adding an organic acid having a pKa value of less than 4 to the mixture containing the prepolymer. including At least one of the two or more different monomers for optical materials is an isocyanate compound.

[0154] Production method B includes a preparation step, a prepolymerization step, and an acid addition step, thereby suppressing streaks in the obtained optical material and shortening the production time of the optical material.

[0155] In addition to the above steps, production method B further adds at least the remainder of the two or more different monomers for optical materials to the mixture containing the prepolymer, thereby obtaining a polymerizable composition containing two or more different monomers for optical materials, a prepolymer, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, which is a polymerizable composition production step. A curing step of curing two or more different monomers for optical materials in the polymerizable composition to obtain an optical material which is a cured product of the polymerizable composition. It is preferably included.

[0156] By further including a polymerizable composition production step and a curing step in production method B, streaks in the obtained optical material can be better suppressed, and the production time of the optical material can be better shortened.

[0157] In the preparation step, the content of the basic polymerization catalyst with respect to a total of 100 parts by mass of the two or more different monomers for optical materials is not particularly limited. For example, the content of the basic polymerization catalyst may be 0.010 parts by mass to 2.0 parts by mass with respect to a total of 100 parts by mass of the two or more different monomers for optical materials. The polymerizable composition with the basic polymerization catalyst content within the above range contains a large amount of the basic polymerization catalyst as compared with the conventional manufacturing method of optical materials. Therefore, similar to the case of Production Method A, a high-quality optical material with suppressed veining can be obtained in a shorter time than before. Similar to the case of Production Method A, in Production Method B, heating of the polymerizable composition for optical materials is not necessarily required. Production Method B includes a preparation step, a prepolymerization step, a polymerizable composition production step, and a curing step, thereby suppressing convection in the mold where the polymerization reaction is carried out and suppressing the generation of veining in the resulting cured product. In addition, by including the prepolymerization step, Production Method B can maintain the storage stability of the mixture (for example, the polymerizable composition) better than in the case without prepolymerization. For example, when a mixture containing a prepolymer is stored for a certain period, the polymerization reaction in the mixture can be suppressed. That is, a longer pot life can be ensured. Furthermore, by adding an organic acid with a pKa value of less than 4 to the mixture containing the prepolymer in the acid addition step, the activity of the basic polymerization catalyst is suppressed and the pot life of the polymerizable composition is further improved.

[0158] <Preparation Step> Production Method B includes a preparation step of preparing two or more different monomers for optical materials and a basic polymerization catalyst.

[0159] The amount of the basic polymerization catalyst in the preparation step may be determined according to the types of isocyanate compounds contained in two or more different monomers for optical materials. For example, the content of the basic polymerization catalyst may be determined according to the presence or absence of an aromatic ring in the isocyanate compound.

[0160] When at least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, the amount of the basic polymerization catalyst may be 0.010 parts by mass to 0.50 parts by mass with respect to a total of 100 parts by mass of the two or more different monomers for optical materials.

[0161] By using 0.010 parts by mass or more of a basic polymerization catalyst with respect to 100 parts by mass of monomers for two or more different optical materials, the polymerization reaction can be promoted well, so that a high-quality optical material with suppressed vein patterns can be obtained in a short time. In addition, by promoting the polymerization reaction well, the releasability when taking out the cured product from the mold can be improved. From the above viewpoints, it is preferable to use 0.015 parts by mass or more of the basic polymerization catalyst with respect to 100 parts by mass of monomers for two or more different optical materials, and more preferably 0.030 parts by mass or more.

[0162] The range of the content of the basic polymerization catalyst described above may be appropriately changed depending on the types of the monomers for optical materials and the basic polymerization catalyst.

[0163] For example, when the monomers for optical materials include m-xylylene diisocyanate (an isocyanate compound having an aromatic ring), 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and the basic polymerization catalyst includes 3,5-lutidine, it is preferable to use 0.015 parts by mass or more of the basic polymerization catalyst with respect to 100 parts by mass of monomers for two or more different optical materials, and more preferably 0.020 parts by mass or more.

[0164] For example, when the monomers for optical materials include m-xylylene diisocyanate and 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, and the basic polymerization catalyst includes 3,5-lutidine, it is preferable to use 0.010 parts by mass or more of the basic polymerization catalyst with respect to 100 parts by mass of monomers for two or more different optical materials, and more preferably 0.015 parts by mass or more.

[0165] By using 0.50 parts by mass or less of a basic polymerization catalyst with respect to 100 parts by mass of monomers for two or more different optical materials, for example, the handleability when injecting the polymerizable composition into a mold can be improved. From the above viewpoints, the amount of the basic polymerization catalyst is preferably 0.09 parts by mass or less, more preferably 0.07 parts by mass or less, and still more preferably 0.05 parts by mass or less with respect to 100 parts by mass of monomers for two or more different optical materials.

[0166] When at least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, the amount of the basic polymerization catalyst may be more than 0.05 parts by mass and 2.0 parts by mass or less with respect to 100 parts by mass in total of the two or more different monomers for optical materials.

[0167] By using a basic polymerization catalyst of more than 0.05 parts by mass with respect to 100 parts by mass of monomers for two or more different optical materials, the polymerization reaction can be promoted well, so that a high-quality optical material with suppressed vein patterns can be obtained in a short time. Also, by promoting the polymerization reaction well, the mold release property when removing the cured product from the mold can be improved. From the above viewpoints, the amount of the basic polymerization catalyst is preferably 0.08 parts by mass or more, more preferably 0.10 parts by mass or more, still more preferably 0.13 parts by mass or more, and particularly preferably 0.17 parts by mass or more with respect to 100 parts by mass of monomers for two or more different optical materials.

[0168] The above-mentioned range of the content of the basic polymerization catalyst may be appropriately changed depending on the types of the monomers for optical materials and the basic polymerization catalyst.

[0169] For example, when the monomers for optical materials include 2,5(6)-bis(isocyanatomethyl)-bicyclo-[2.2.1]-heptane, pentaerythritol tetrakis(3-mercaptopropionate), and 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, and the polymerization catalyst includes 3,5-lutidine, it is preferable to use 0.10 parts by mass or more, and more preferably 0.17 parts by mass or more of the polymerization catalyst with respect to 100 parts by mass of two or more different monomers for optical materials.

[0170] By using 2.0 parts by mass or less of a basic polymerization catalyst with respect to 100 parts by mass of two or more different monomers for optical materials, for example, the handleability when injecting the polymerizable composition into a mold can be improved. From the above viewpoints, the amount of the basic polymerization catalyst is preferably 1.5 parts by mass or less with respect to 100 parts by mass of two or more different monomers for optical materials. Also, depending on the types of the monomers for optical materials and the basic polymerization catalyst, the basic polymerization catalyst may be 1.0 part by mass or less, 0.3 part by mass or less, or 0.15 part by mass or less with respect to 100 parts by mass of two or more different monomers for optical materials.

[0171] The amount of the basic polymerization catalyst can be appropriately set according to the type of the basic polymerization catalyst, the types and amounts of the monomers used (isocyanate compounds, active hydrogen compounds, other components, etc.), the shape of the desired molded article, and the like.

[0172] <Prepolymerization step> Production method B includes a prepolymerization step of obtaining a mixture containing a prepolymer by mixing a part of two or more different monomers for optical materials and at least a part of a basic polymerization catalyst, and polymerizing at least a part of a part of two or more different monomers for optical materials to obtain a prepolymer.

[0173] The inventors considered that the occurrence of convection due to the non-uniform temperature distribution within the mold where the polymerization reaction occurs is one of the causes of the formation of streaks in the resulting cured product. Therefore, the inventors focused on producing a prepolymer by previously polymerizing a part of the monomers for optical materials, and increasing the viscosity of the polymerizable composition for optical materials by including the prepolymer in the polymerizable composition. By this, convection within the mold can be suppressed. Also, production method B can make it difficult to generate a temperature difference between the inside and the outer periphery of the mold by preventing self-heat from escaping to the outside. From the above viewpoints combined, it is presumed that production method B can suppress the streaks in the resulting cured product.

[0174] According to production method B, a prepolymer excellent in pot life can be obtained.

[0175] There is no particular limitation on the aspect of "a part of two or more different monomers for optical materials". For example, "a part of two or more different monomers for optical materials" may be the amount of a part of each of two or more different monomers for optical materials. Also, "a part of two or more different monomers for optical materials" may be all of one or more kinds of monomers for optical materials among two or more different monomers for optical materials.

[0176] The basic polymerization catalyst used in the prepolymerization step may be a part or all of the basic polymerization catalyst contained in the polymerizable composition. When using a part of the basic polymerization catalyst contained in the polymerizable composition in the prepolymerization step, similar to "a part of two or more different monomers for optical materials", there is no particular limitation on the aspect of "a part of the basic polymerization catalyst". For example, "a part of the basic polymerization catalyst" may be the amount of a part of the basic polymerization catalyst.

[0177] When using a part as a basic polymerization catalyst, from the viewpoint of ensuring a long pot life, a part of the basic polymerization catalyst is preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass, and still more preferably 15 to 50 parts by mass within 100 parts by mass of the basic polymerization catalyst.

[0178] A part of two or more different monomers for optical materials is preferably 5 to 95 parts by mass, more preferably 20 to 80 parts by mass, and still more preferably 30 to 70 parts by mass within 100 parts by mass of the two or more different monomers for optical materials from the viewpoint of ensuring a long pot life.

[0179] Examples of specific embodiments of the prepolymerization step are shown below, but the prepolymerization step in Production Method B is not limited to the following embodiments.

[0180] (Embodiment a) The prepolymerization step of Embodiment a is a step of obtaining a mixture containing a prepolymer by mixing a part of two or more different monomers for optical materials and all of the basic polymerization catalyst, and polymerizing at least a part of the part of the two or more different monomers for optical materials to obtain a prepolymer.

[0181] In Embodiment a, it is preferable that a part of the two or more different monomers for optical materials is composed of all of one monomer for optical material among the two or more different monomers for optical materials and a part of the other monomers for optical materials other than one monomer for optical material.

[0182] (Embodiment b) The prepolymerization step of Embodiment b is a step of obtaining a mixture containing a prepolymer by mixing a part of two or more different monomers for optical materials and a part of the basic polymerization catalyst, and polymerizing at least a part of the part of the two or more different monomers for optical materials to obtain a prepolymer. When Production Method B includes the prepolymerization step of Embodiment b, the polymerizable composition production step described below is to add at least the remainder of two or more different monomers for optical materials and the remainder of the basic polymerization catalyst to a mixture containing the prepolymer, thereby obtaining a polymerizable composition containing two or more different monomers for optical materials, the prepolymer, the basic polymerization catalyst, and an organic acid having a pKa value of less than 4.

[0183] In Embodiment b, it is preferable that two or more different monomers for optical materials contain an isocyanate compound, a part of the two or more different monomers for optical materials contains a part of the isocyanate compound, and the remainder of the two or more different monomers for optical materials contains the remainder of the isocyanate compound.

[0184] <Acid addition step> Production Method B includes an acid addition step of adding an organic acid having a pKa value of less than 4 to a mixture containing the prepolymer.

[0185] The amount of the organic acid having a pKa value of less than 4 added to the mixture containing the prepolymer is not particularly limited. For example, the content of the organic acid having a pKa value of less than 4 with respect to 100 parts by mass in total of two or more different monomers for optical materials as raw materials of the prepolymer may be 0.001 part by mass to 1 part by mass. When the content of the organic acid having a pKa value of less than 4 with respect to 100 parts by mass in total of two or more different monomers for optical materials is 0.001 part by mass or more, the increase in the viscosity of the polymerizable composition is effectively suppressed. From the above viewpoints, the content of the organic acid having a pKa value of less than 4 with respect to 100 parts by mass in total of two or more different monomers for optical materials is preferably 0.005 part by mass or more, and more preferably 0.01 part by mass or more.

[0186] When the content of the organic acid having a pKa value of less than 4 with respect to 100 parts by mass in total of two or more different monomers for optical materials is 1 part by mass or less, in the curing step, the dissociation of the salt formed by the organic acid and the basic polymerization catalyst due to heat is promoted, and the activity of the basic polymerization catalyst is likely to be expressed. Thereby, the polymerization reaction can proceed rapidly. From the above viewpoints, it is preferable that the content of the organic acid having a pKa value of less than 4 is 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, based on 100 parts by mass in total of two or more different monomers for optical materials.

[0187] The molar ratio (X / Y) of the organic acid (X) having a pKa value of less than 4 to the basic polymerization catalyst (Y) is preferably from 0.1 to 2.0, more preferably from 0.15 to 1.25, and even more preferably from 0.2 to 1.2.

[0188] From the viewpoint of favorably expressing the activity of the basic polymerization catalyst, the number of moles (x) of the functional groups of the organic acid having a pKa value of less than 4 in the mixture containing the prepolymer is preferably less than the number of moles (y) of the functional groups of the basic polymerization catalyst (the molar ratio represented by x / y is less than 1.0).

[0189] <Viscosity adjustment step> Production method B preferably further includes a viscosity adjustment step of adjusting the viscosity of the mixture containing the prepolymer to 30 mPa·s to 2000 mPa·s after the prepolymerization step and before the polymerizable composition production step. When the viscosity of the mixture containing the prepolymer is within the above range, from the viewpoint of suppressing streaks in the resulting optical material, the viscosity of the polymerizable composition produced in the polymerizable composition production step can be within an appropriate range. As a result, streaks in the resulting optical material can be suppressed.

[0190] From the above viewpoints, the viscosity of the mixture containing the prepolymer is preferably 40 mPa·s to 2000 mPa·s, and more preferably 50 mPa·s to 1800 mPa·s. The above viscosity is measured using a B-type viscometer under the conditions of 25°C and 60 rpm (revolutions per minute).

[0191] There is no particular limitation on the method for adjusting the viscosity of the mixture containing the prepolymer. For example, the viscosity of the mixture containing the prepolymer may be adjusted by methods such as adding a high-viscosity compound, heating, and stirring.

[0192] The temperature for preparing the mixture containing the prepolymer is not particularly limited as long as it is a temperature at which the prepolymer can be obtained by a polymerization reaction. For example, it may be 20°C to 50°C, or may be 25°C to 45°C. The stirring time for preparing the mixture containing the prepolymer is not particularly limited as long as it is a stirring time at which the prepolymer can be obtained by a polymerization reaction. For example, it may be 30 minutes to 5 hours, or may be 1 hour to 5 hours.

[0193] Specifically, as a method for preparing the mixture containing the prepolymer, it may be a method of preparing the mixture containing the prepolymer while adjusting the viscosity by stirring under the conditions of 40°C and 3 hours.

[0194] <Polymerizable composition production step> Production method B includes a polymerizable composition production step of obtaining a polymerizable composition containing at least two or more different monomers for optical materials, a prepolymer, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, by adding at least the remaining portions of two or more different monomers for optical materials to the mixture containing the prepolymer.

[0195] The polymerizable composition production step is a step of obtaining a polymerizable composition for optical materials containing at least two or more different monomers for optical materials, a prepolymer, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, by adding at least the remaining portions of two or more different monomers for optical materials to the mixture containing the prepolymer. Thereby, it is possible to prevent the occurrence of polymerization between the prepolymer and the remaining portions of two or more different monomers for optical materials until the mixture containing the prepolymer and the remaining portions of two or more different monomers for optical materials are mixed. Therefore, by performing the polymerizable composition production step at an appropriate time, for example, the handleability when injecting the polymerizable composition into a mold can be improved. In the process of manufacturing the coincidence composition, when adding the remainder of at least two or more different monomers for optical materials to the mixture containing the prepolymer, the addition may be carried out once or divided into multiple times.

[0196] Note that the "remainder of two or more different monomers for optical materials" means the remaining part of two or more different monomers for optical materials with respect to the "part of two or more different monomers for optical materials" in the prepolymerization process. The "remainder of two or more different monomers for optical materials" may be a monomer for optical materials having a functional group that polymerizes with respect to the polymerizable functional group of the prepolymer, and the amount of the functional group that polymerizes with respect to the polymerizable functional group of the prepolymer is an amount (i.e., equivalent) that can substantially polymerize with all of the polymerizable functional groups of the prepolymer. From the viewpoint of enhancing the optical uniformity of the polymerizable composition, it is preferable that the remainder of two or more different monomers for optical materials contains the same type of monomers as the monomers for optical materials constituting the prepolymer.

[0197] The temperature for mixing the above components is not particularly limited, but it is preferably 30 °C or lower, and more preferably room temperature (25 °C) or lower. In some cases, it may be preferable to make the temperature for mixing each component even lower than 25 °C. However, when the solubility of additives such as internal release agents and the above components is not good, the above components may be heated in advance to dissolve the above additives in the above components.

[0198] Specific embodiments of the process for manufacturing the polymerizable composition include the following embodiments.

[0199] First, an organic acid with a pKa value of less than 4 and other additives (such as an internal release agent) are charged into the mixture containing the prepolymer to prepare a mixed solution. After stirring this mixed solution at 25 °C for 1 hour to completely dissolve each component, degassing is performed to obtain a first mixed solution. Further, the remainder of the monomer for the optical material and, if necessary, the remainder of the basic polymerization catalyst are stirred at 25°C for 30 minutes to be completely dissolved, thereby obtaining a second mixed solution. Then, the first mixed solution and the second mixed solution are mixed, stirred, and degassed to obtain a polymerizable composition.

[0200] <Liquid feeding step> Production method B may further include a liquid feeding step of feeding the polymerizable composition into a casting mold after the polymerizable composition production step and before the curing step. The liquid feeding step may be a step of feeding the polymerizable composition into the casting mold while remixing the polymerizable composition in a static mixer. The liquid feeding step may be a step of feeding the polymerizable composition into the casting mold while remixing the polymerizable composition by a dynamic mixer. When the polymerizable composition is fed while being remixed, the non-uniformity of the distribution of the polymerizable composition can be eliminated while the polymerizable composition is being fed into the mold. Therefore, the veins of the obtained cured product can be suppressed.

[0201] <Curing step> Production method B includes a curing step of obtaining an optical material that is a cured product of the polymerizable composition by curing two or more different monomers for the optical material in the polymerizable composition. The specific embodiments and preferred embodiments of the curing step in production method B are the same as the specific embodiments and preferred embodiments described in the <Curing step> section of the above-described production method A.

[0202] <Second prepolymerization step> In addition to the above-described steps, production method B further includes mixing the remainder of two or more different monomers for the optical material and the remainder of the basic polymerization catalyst, and polymerizing at least a part of the remainder of the two or more different monomers for the optical material to obtain a second prepolymer, thereby obtaining a mixture containing the second prepolymer, i.e., a second prepolymerization step. To a mixture containing a prepolymer obtained by a prepolymerization step, a polymerizable composition containing the prepolymer, the second prepolymer, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4 is obtained by adding the mixture containing the second prepolymer. A polymerizable composition production step. A curing step of obtaining an optical material which is a cured product of the polymerizable composition by curing the prepolymer and the second prepolymer in the polymerizable composition may be included.

[0203] By including the above configuration, Production Method B can obtain a mixture containing a prepolymer obtained by a prepolymerization step and a mixture containing a second prepolymer obtained by a second prepolymerization step. Thereby, since the viscosities of the mixture containing the prepolymer and the mixture containing the second prepolymer can be made close to each other, the two can be more easily mixed.

[0204] In the second prepolymerization step, the specific embodiments and preferred embodiments of two or more different monomers for optical materials and the basic polymerization catalyst are the same as the specific embodiments and preferred embodiments of two or more different monomers for optical materials and the basic polymerization catalyst in the prepolymerization step.

[0205] When Production Method B includes a second prepolymerization step, in the polymerizable composition production step, a polymerizable composition containing the prepolymer, the second prepolymer, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4 is obtained by adding the mixture containing the second prepolymer to the mixture containing the prepolymer obtained by the prepolymerization step. In the polymerizable composition production step, the specific embodiments and preferred embodiments of the mixture containing the prepolymer are the same as the specific embodiments and preferred embodiments in the above <Polymerizable Composition Production Step>.

[0206] When Production Method B includes a second prepolymerization step, the curing step is a step of obtaining an optical material that is a cured product of the polymerizable composition by curing the prepolymer and the second prepolymer in the polymerizable composition. In the above curing step, the specific embodiments and preferred embodiments of the prepolymer are the same as the specific embodiments and preferred embodiments of the prepolymer in the above <Curing Step>.

[0207] <Annealing Step> Production Method B may optionally include an annealing step of annealing the cured polymerizable composition. The specific embodiments and preferred embodiments of the annealing step in Production Method B are the same as the specific embodiments and preferred embodiments of the annealing step in Production Method A.

[0208] <Other Steps> Production Method B may optionally be provided with other steps. The specific embodiments and preferred embodiments of the other steps in Production Method B are the same as the specific embodiments and preferred embodiments of the other steps in Production Method A.

[0209] <Use of Optical Material> The specific embodiments and preferred embodiments of the use of the optical material in Production Method B are the same as the specific embodiments and preferred embodiments of the use of the optical material in Production Method A.

Examples

[0210] Examples of the present disclosure are shown below, but the present disclosure is not limited to the following examples. Unless otherwise specified, "parts" are based on mass.

[0211] 〔Example 1-1〕 1.50 parts by mass of Tinuvin 329 [UV absorber] manufactured by BASF and 43.80 parts by mass of m-xylylene diisocyanate [monomer a1 for optical materials] were mixed and stirred at 25 °C for 1 hour to be completely dissolved to obtain a mixed solution. To this mixed solution, 10.56 parts by mass of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] was added and stirred at 25 °C for 5 minutes to obtain a uniform solution. 0.028 parts by mass of 3,5-lutidine [basic polymerization catalyst, pKa value = 6.15] was added to the obtained solution, and the monomers for optical materials were polymerized by stirring at 40 °C for 1 hour to obtain a mixture containing a prepolymer.

[0212] 3.00 parts by mass of m-xylylene diisocyanate [monomer a1 for optical materials], 0.1 part by mass of JP-506H [release agent] manufactured by Johoku Chemical Industry Co., Ltd., and 0.029 parts by mass of (±)-10-camphorsulfonic acid [organic acid, pKa value = 1.17] were mixed to prepare a mixed solution. This mixed solution and the mixture containing the prepolymer were mixed, and degassing was performed at 400 Pa and 25 °C for 1 hour to obtain Mixture 1 containing a prepolymer. The viscosity and refractive index of Mixture 1 containing a prepolymer are shown in Table 1.

[0213] 5.20 parts by mass of m-xylylene diisocyanate [monomer a1 for optical materials] and 37.44 parts by mass of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] were mixed and stirred at 25 °C for 5 minutes to obtain a uniform solution. 0.01 part by mass of 3,5-lutidine [basic polymerization catalyst, pKa value = 6.15] was added to the obtained uniform solution, and the monomers for optical materials were polymerized by stirring at 40 °C for 1 hour. Thereafter, degassing was performed at 400 Pa and 25 °C for 1 hour to obtain Mixture 2 containing a prepolymer. The viscosity of Mixture 2 containing a prepolymer is shown in Table 1.

[0214] Mixture 1 containing a prepolymer and Mixture 2 containing a prepolymer were mixed at 20 °C to obtain a polymerizable composition. The obtained polymerizable composition was fed to a casting mold (i.e., a mold) while remixing in a static mixer. The viscosity of the polymerizable composition (also referred to as the casting viscosity) when it is fed into the mold and cast was adjusted to the values shown in Table 1. During the feeding, while filtering the polymerizable composition through a 1 μm PTFE filter, it was injected into the cavity of a mold type having a cavity for lens production composed of a 4-curved glass mold (upper mold) with a diameter of 78 mm and a 4-curved glass mold (lower mold) with a diameter of 78 mm at a rate of 10 g / second. The mold type into which the polymerizable composition was injected was placed in a polymerization oven, and the temperature was raised from 20 °C to 120 °C over 10 hours. The molded body in a state where the polymerizable composition was cured was demolded from the mold type, and further annealed at 120 °C for 2 hours to obtain a molded body (lens).

[0215] 〔Example 1-2〕 A molded body (lens) was obtained in the same manner as in Example 1-1 except that the method for producing Mixture 1 containing the prepolymer was changed as follows. 1.50 parts by mass of Tinuvin 329 [ultraviolet absorber] manufactured by BASF and 46.80 parts by mass of m-xylylene diisocyanate [monomer a1 for optical materials] were mixed and stirred at 25 °C for 1 hour to be completely dissolved to obtain a mixed solution. To this mixed solution, 10.56 parts by mass of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] was added and stirred at 25 °C for 5 minutes to obtain a homogeneous solution. 0.028 parts by mass of 3,5-lutidine [basic polymerization catalyst] was added to the obtained homogeneous solution, and the monomers for optical materials were polymerized by stirring at 40 °C for 1 hour to obtain a mixture containing a prepolymer. 0.1 part by mass of JP-506H [release agent] manufactured by Johoku Chemical Industry Co., Ltd. and 0.007 part by mass of methanesulfonic acid [organic acid, pKa value = -2.6] were mixed with the above mixture containing the prepolymer, and degassed at 400 Pa and 25 °C for 1 hour to obtain Mixture 1 containing the prepolymer. The viscosity and refractive index of Mixture 1 containing the prepolymer are shown in Table 1.

[0216] 〔Example 1-3〕 A molded body (lens) was obtained in the same manner as in Example 1-1, except that the basic polymerization catalyst was changed from 3,5-lutidine to 2,6-lutidine [basic polymerization catalyst, pKa value = 6.6], and the addition amount of the organic acid was changed to 0.025 parts by mass.

[0217] [Example 1-4] A molded body (lens) was obtained in the same manner as in Example 1-1, except that the mixture 1 containing the prepolymer and the mixture 2 containing the prepolymer were changed to those shown in Table 1. Specifically, the monomers for optical materials used in the preparation of the mixture 1 containing the prepolymer and the mixture 2 containing the prepolymer were changed from 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] to a mixture of 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane [monomer b2 for optical materials], and the amounts of the respective components were changed to the amounts shown in Table 1.

[0218] [Example 1-5] A molded body (lens) was obtained in the same manner as in Example 1-2, except that the mixture 1 containing the prepolymer and the mixture 2 containing the prepolymer were changed to those shown in Table 1. Specifically, the monomers for optical materials used in the preparation of the mixture 1 containing the prepolymer and the mixture 2 containing the prepolymer were changed from 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] to a mixture of 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane [monomer b2 for optical materials], and the amounts of the respective components were changed to the amounts shown in Table 1.

[0219] [Comparative Example 1-1] In the preparation of Mixture 1 containing a prepolymer, a molded article (lens) was obtained in the same manner as in Example 1-1, except that (±)-10-camphorsulfonic acid was not used.

[0220] [Comparative Example 1-2] In the preparation of Mixture 1 containing a prepolymer, a molded article (lens) was obtained in the same manner as in Example 1-1, except that octanoic acid [organic acid, pKa value = 4.90] was used instead of (±)-10-camphorsulfonic acid.

[0221] [Comparative Example 1-3] In the preparation of Mixture 1 containing a prepolymer, a molded article (lens) was obtained in the same manner as in Example 1-3, except that (±)-10-camphorsulfonic acid was not used.

[0222] [Comparative Example 1-4] In the preparation of Mixture 1 containing a prepolymer, a molded article (lens) was obtained in the same manner as in Example 1-3, except that octanoic acid was used instead of (±)-10-camphorsulfonic acid.

[0223] [Example 2-1] 0.10 part by mass of an internal mold release agent for MR manufactured by Mitsui Chemicals [internal mold release agent], 1.5 parts by mass of Tinuvin 329 manufactured by BASF [ultraviolet absorber], and 43.07 parts by mass of a mixture of 2,5-bis(isocyanatomethyl)-bicyclo-[2.2.1]-heptane and 2,6-bis(isocyanatomethyl)-bicyclo-[2.2.1]-heptane [monomer a1 for optical materials] were mixed and stirred at 25°C for 1 hour to completely dissolve to obtain a mixed solution. To this mixed solution, 3.47 parts by mass of pentaerythritol tetrakis(3-mercaptopropionate) [monomer b2 for optical materials] and 3.70 parts by mass of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] were added and stirred at 25°C for 5 minutes to obtain a homogeneous solution. 0.13 part by mass of 3,5-lutidine [basic polymerization catalyst, pKa value = 6.15] was added to the obtained homogeneous solution, and the monomers for optical materials were polymerized by stirring at 40°C for 3 hours to obtain a mixture containing a prepolymer.

[0224] A mixture of 2,5-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane and 2,6-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane [monomer a1 for optical materials] (5.00 parts by mass) and (±)-10-camphorsulfonic acid [organic acid, pKa value = 1.17] (0.165 parts by mass) were mixed to prepare a mixed solution. This mixed solution and the mixture containing the prepolymer were mixed, and degassing was performed at 400 Pa and 25 °C for 1 hour to obtain a mixture 1 containing the prepolymer. The viscosities and refractive indices of the mixture 1 containing the prepolymer are shown in Table 1.

[0225] A mixture of 2,5-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane and 2,6-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane [monomer a1 for optical materials] (2.53 parts by mass), pentaerythritol tetrakis(3-mercaptopropionate) [monomer b2 for optical materials] (20.43 parts by mass), and 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [monomer b1 for optical materials] (21.80 parts by mass) was mixed and stirred at 25 °C for 5 minutes to obtain a homogeneous solution. To the obtained homogeneous solution, 0.02 parts by mass of 3,5-lutidine [basic polymerization catalyst, pKa value = 6.15] was added, and the monomers for optical materials were polymerized by stirring at 40 °C for 3 hours. Thereafter, degassing was performed at 400 Pa and 25 °C for 1 hour to obtain a mixture 2 containing the prepolymer. The viscosities and refractive indices of the mixture 2 containing the prepolymer are shown in Table 1.

[0226] The mixture 1 containing the prepolymer and the mixture 2 containing the prepolymer were mixed at 20 °C to obtain a polymerizable composition. The obtained polymerizable composition was fed to a casting mold (i.e., a mold type) while remixing in a static mixer. The viscosity of the polymerizable composition (also referred to as the casting viscosity) when it is fed to the mold and cast was adjusted to the values shown in Table 1. During liquid delivery, while filtering the polymerizable composition through a 1 μm PTFE filter, it was injected into the cavity of a mold type having a cavity for lens production, which is composed of a 4-curved glass mold (upper mold) with a diameter of 78 mm and a 4-curved glass mold (lower mold) with a diameter of 78 mm, at a rate of 10 g / second. The mold type into which the polymerizable composition was injected was placed in a polymerization oven, and the temperature was raised from 20 °C to 120 °C over 10 hours. The molded body in a cured state of the polymerizable composition was demolded from the mold type, and further annealed at 120 °C for 2 hours to obtain a molded body (lens).

[0227] [Example 2-2] A molded body (lens) was obtained in the same manner as in Example 2-1, except that the method for producing Mixture 1 containing the prepolymer was changed as follows. 0.1 part by mass of an internal mold release agent for MR manufactured by Mitsui Chemicals [Internal mold release agent], 1.5 parts by mass of Tinuvin 329 manufactured by BASF [UV absorber], and 48.07 parts by mass of a mixture of 2,5-bis(isocyanatomethyl)-bicyclo-[2.2.1]-heptane and 2,6-bis(isocyanatomethyl)-bicyclo-[2.2.1]-heptane [Monomer a1 for optical materials] were mixed and stirred at 25 °C for 1 hour to be completely dissolved to obtain a mixed solution. To this mixed solution, 3.47 parts by mass of pentaerythritol tetrakis(3-mercaptopropionate) [Monomer b2 for optical materials] and 3.70 parts by mass of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane [Monomer b1 for optical materials] were added and stirred at 25 °C for 5 minutes to obtain a uniform solution. 0.13 part by mass of 3,5-lutidine [Basic polymerization catalyst] was added to the obtained uniform solution and stirred at 40 °C for 3 hours to polymerize the monomers for optical materials, thereby obtaining a mixture containing a prepolymer. 0.06 part by mass of methanesulfonic acid [Organic acid, pKa value = -2.6] and the mixture containing the prepolymer were mixed, and degassed at 400 Pa and 25 °C for 1 hour to obtain Mixture 1 containing the prepolymer. The viscosity and refractive index of Mixture 1 containing the prepolymer are shown in Table 1.

[0228] [Comparative Example 2-1] In the preparation of Mixture 1 containing a prepolymer, a molded article (lens) was obtained in the same manner as in Example 2-1, except that (±)-10-camphorsulfonic acid was not used.

[0229] [Comparative Example 2-2] In the preparation of Mixture 1 containing a prepolymer, a molded article (lens) was obtained in the same manner as in Example 2-1, except that octanoic acid [organic acid, pKa value = 4.90] was used instead of (±)-10-camphorsulfonic acid.

[0230] [Evaluation] The following evaluations were performed on the polymerizable compositions and molded articles obtained in each example or comparative example. The results are shown in Tables 1 and 2.

[0231] (Viscosity of the mixture containing the prepolymer) The mixture containing the prepolymer was stirred at 25 °C and 60 rpm, and the viscosity was measured using a B-type viscometer (Spindle No. 2: Brookfield).

[0232] (Refractive index of the mixture containing the prepolymer) Using a refractometer (RA-600: Kyoto Electronics Industry Co., Ltd.), the refractive index of the mixture containing the prepolymer at 20 °C was measured.

[0233] (Viscosity of the polymerizable composition) The polymerizable composition was stirred at 25 °C and 60 rpm, and the viscosity was measured using a B-type viscometer (Spindle No. 2: Brookfield).

[0234] (Rate of increase in viscosity) With the horizontal axis (=X) being time (hr) and the vertical axis (=Y) being the viscosity (mPa·S) of the polymerizable composition, the change in viscosity over time was plotted and approximated by the following equation. The value of b in the equation was taken as the rate of increase in viscosity. The viscosity of the polymerizable composition was measured using a B-type viscometer (Spindle No. 2: Brookfield) under the conditions of 25 °C and 30 rpm. Y = a * exp(b * X) The smaller the numerical value of the thickening speed slope, the slower the viscosity increase speed and the better the pot life.

[0235] (Pot life) The state of the polymerizable composition 30 minutes after mixing mixture 1 containing a prepolymer and mixture 2 containing a prepolymer was evaluated according to the following criteria. A: It is still pourable 30 minutes after mixing. B: The viscosity increases 30 minutes after mixing and it is not pourable.

[0236] (Vein pattern) The molded body was projected with an ultra-high pressure mercury lamp (light source model OPM-252HEG: manufactured by Ushio Inc.), and the transmitted image was visually observed and evaluated according to the following criteria. A: No vein pattern was observed. Specifically, no vein pattern with a length of 1.0 mm or more was visually observed within and outside the range of a radius of 15 mm from the center of the molded body. B: Although a vein pattern was observed, it was generally acceptable as a product. Specifically, although a vein pattern with a length of 1.0 mm or more was visually observed outside the range of a radius of 15 mm from the center of the molded body, no vein pattern with a length of 1.0 mm or more was visually observed within the range of a radius of 15 mm from the center of the molded body, and it was generally acceptable as a product. C: A vein pattern was observed and it was not acceptable as a product. Specifically, a vein pattern with a length of 1.0 mm or more was visually observed within and outside the range of a radius of 15 mm from the center of the molded body.

[0237]

Table 1

[0238]

Table 2

[0239] As shown in Table 1 and Table 2, the polymerizable composition of the examples using an organic acid with a pKa value of less than 4 together with a basic polymerization catalyst had an increased viscosity suppressed compared to the polymerizable composition of the comparative examples using no organic acid or an organic acid with a pKa value of 4 or more, and had a good pot life. Further, no veins were observed in the molded article (cured product) obtained using the polymerizable composition of the examples.

[0240] The disclosures of Japanese Patent Application Nos. 2023-135607 and 2023-135613 are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. A polymerizable composition for an optical material, comprising two or more different monomers for an optical material, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein the number of moles of the functional group of the organic acid having a pKa value of less than 4 is less than the number of moles of the functional group of the basic polymerization catalyst, wherein the two or more different monomers for an optical material include an isocyanate compound and an active hydrogen compound, and the active hydrogen compound includes a polythiol compound, and having a viscosity of 10 mPa·s to 1000 mPa·s as measured by a B-type viscometer under the conditions of 25°C and 60 rpm.

2. A polymerizable composition for an optical material, comprising two or more different monomers for an optical material, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein the basic polymerization catalyst includes a basic polymerization catalyst having a pKa value of 4 to 8, wherein the two or more different monomers for an optical material include an isocyanate compound and an active hydrogen compound, and the active hydrogen compound includes a polythiol compound, and having a viscosity of 10 mPa·s to 1000 mPa·s as measured by a B-type viscometer under the conditions of 25°C and 60 rpm.

3. The polymerizable composition for an optical material according to claim 1 or claim 2, wherein at least one of the two or more different monomers for an optical material is an isocyanate compound having an aromatic ring, and the content of the basic polymerization catalyst is 0.010 parts by mass to 0.50 parts by mass with respect to 100 parts by mass in total of the two or more different monomers for an optical material.

4. The polymerizable composition for an optical material according to claim 1 or claim 2, wherein at least one of the two or more different monomers for an optical material is an isocyanate compound having no aromatic ring, and the content of the basic polymerization catalyst is more than 0.05 parts by mass and 2.0 parts by mass or less with respect to 100 parts by mass in total of the two or more different monomers for an optical material.

5. The polymerizable composition for an optical material according to claim 1 or claim 2, further comprising a prepolymer which is a polymer of the two or more different monomers for an optical material and has a polymerizable functional group.

6. The polymerizable composition for an optical material according to claim 1 or claim 2, wherein the two or more different monomers for an optical material further include at least one active hydrogen compound selected from the group consisting of a polythiol compound having two or more mercapto groups, a hydroxythiol compound containing one or more mercapto groups and one or more hydroxyl groups, a polyol compound containing two or more hydroxyl groups, and an amine compound.

7. The polymerizable composition for an optical material according to claim 1 or claim 2, wherein the total proportion of the isocyanate compound and the active hydrogen compound in the whole of the two or more different monomers for an optical material is more than 70% by mass.

8. A prepolymer which is a polymer of two or more different monomers for an optical material and has polymerizable functional groups, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein the two or more different monomers for an optical material include an isocyanate compound and an active hydrogen compound, and the active hydrogen compound includes a polythiol compound, the viscosity measured at 25°C and 60 rpm with a B-type viscometer is 10 mPa·s to 2000 mPa·s, at least one of the two or more different monomers for an optical material is an isocyanate compound having an aromatic ring, a polymerizable prepolymer composition for an optical material, wherein the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the prepolymer is 0.002 parts by mass to 1 part by mass.

9. A prepolymer which is a polymer of two or more different monomers for an optical material and has polymerizable functional groups, a basic polymerization catalyst, and an organic acid having a pKa value of less than 4, wherein the two or more different monomers for an optical material include an isocyanate compound and an active hydrogen compound, and the active hydrogen compound includes a polythiol compound, the viscosity measured at 25°C and 60 rpm with a B-type viscometer is 10 mPa·s to 2000 mPa·s, at least one of the two or more different monomers for an optical material is an isocyanate compound having no aromatic ring, a polymerizable prepolymer composition for an optical material, wherein the content of the basic polymerization catalyst with respect to 100 parts by mass in total of the prepolymer is 0.1 parts by mass to 4.0 parts by mass.

10. A cured product of the polymerizable composition for an optical material according to claim 1 or claim 2.

11. A cured product of the polymerizable prepolymer composition for an optical material according to claim 8 or claim 9.

12. A preparation step of preparing two or more different monomers for an optical material and a basic polymerization catalyst, a prepolymerization step of mixing a part of the two or more different monomers for an optical material and at least a part of the basic polymerization catalyst, and polymerizing at least a part of the part of the two or more different monomers for an optical material to obtain a prepolymer, thereby obtaining a mixture containing the prepolymer. An acid addition step of adding an organic acid having a pKa value of less than 4 to the mixture containing the prepolymer, A method for producing an optical material, wherein the two or more different monomers for optical materials include an isocyanate compound and an active hydrogen compound, and the active hydrogen compound includes a polythiol compound.

13. At least one of the two or more different monomers for optical materials is an isocyanate compound having an aromatic ring, The method for producing an optical material according to claim 12, wherein the total amount of the two or more different monomers for optical materials in the preparation step is 100 parts by mass, and the amount of the basic polymerization catalyst is 0.010 parts by mass to 0.50 parts by mass.

14. At least one of the two or more different monomers for optical materials is an isocyanate compound having no aromatic ring, The method for producing an optical material according to claim 12, wherein the total amount of the two or more different monomers for optical materials in the preparation step is 100 parts by mass, and the amount of the basic polymerization catalyst is more than 0.05 parts by mass and 2.0 parts by mass or less.

15. Furthermore, by adding at least the remainder of the two or more different monomers for optical materials to the mixture containing the prepolymer, a polymerizable composition for an optical material containing the two or more different monomers for optical materials, the prepolymer, the basic polymerization catalyst, and an organic acid having a pKa value of less than 4 is obtained. A polymerizable composition production step for an optical material, A curing step of obtaining an optical material that is a cured product of the polymerizable composition for an optical material by curing the two or more different monomers for optical materials in the polymerizable composition for an optical material. The method for producing an optical material according to claim 12.

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