Novel compound, isocyanate composition comprising same, and polymerizable composition comprising isocyanate composition

Abstract

The present invention relates to a novel compound, an isocyanate composition comprising same, and a polymerizable composition comprising the isocyanate composition. An isocyanate composition comprising a compound represented by chemical formula 1 according to the present invention can be used in a polymerizable composition for manufacturing an optical element. An optical element manufactured from a polymerizable composition comprising the isocyanate composition has high transparency, an excellent glass transition temperature, and improved impact resistance.

Description

Novel compound, isocyanate composition comprising same, and polymerizable composition comprising said isocyanate composition

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0187694, filed December 20, 2023, and Korean Patent Application No. 10-2024-0189145, filed December 17, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a novel compound, an isocyanate composition comprising the same, and a polymerizable composition comprising the isocyanate composition.

[0004]

[0005] Isocyanate compounds such as xylylene diisocyanate (XDI) are raw materials for poly(thio)urethanes used in advanced optical lenses and flexible displays.

[0006] The physical properties of isocyanate compounds influence the optical properties of poly(thio)urethane lenses, such as transparency and refractive index. Accordingly, research and development are ongoing on isocyanate compositions for obtaining poly(thio)urethane lenses with superior physical properties.

[0007]

[0008] The present invention aims to provide a novel compound, an isocyanate composition comprising the same, and a polymerizable composition comprising the isocyanate composition.

[0009]

[0010] According to one embodiment of the present invention, a compound represented by the following chemical formula 1 is provided:

[0011] [Chemical Formula 1]

[0012]

[0013] In the above chemical formula 1,

[0014] n1 to n3 are each independently integers from 0 to 6,

[0015] R1 to R6 are each independently hydrogen, deuterium, tritium, or C 1-6 It's alkyl.

[0016] In one implementation, n1 to n3 can each independently be an integer from 1 to 3.

[0017] In one embodiment, R1 to R6 can all be hydrogen.

[0018] In one embodiment, the compound may be represented by the following chemical formula 1-1:

[0019] [Chemical Formula 1-1]

[0020]

[0021] According to another embodiment of the present invention, an isocyanate composition is provided, which comprises xylylene diisocyanate and a compound represented by the above chemical formula 1, wherein the content of the compound represented by the above chemical formula 1 is from more than 0 ppm to less than 1000 ppm:

[0022] In one embodiment, the content of the compound represented by the chemical formula 1 in the isocyanate composition may be 0.1 ppm to 1000 ppm.

[0023] In one embodiment, the isocyanate composition may further include at least one selected from the group consisting of chloromethylbenzyl isocyanate, isocyanomethylbenzaldehyde, and isocyanomethylbenznitrile.

[0024] According to another embodiment of the present invention, a polymerizable composition comprising the isocyanate composition and a polyol and / or polythiol component is provided.

[0025] In one embodiment, the polyol and / or polythiol component may include one or more of 2,3-bis(2-sulfanylethylsulfanyl)propane-1-thiol, 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, alone or in combination.

[0026] The above polymerizable composition may further include a polymerization initiator, an internal release agent, and an ultraviolet absorber.

[0027] According to another embodiment of the present invention, an optical device is provided comprising a polymer in which the polymerizable composition is polymerized.

[0028]

[0029] The compound represented by Chemical Formula 1 of the present invention is added to an isocyanate composition to improve low-temperature stability. The isocyanate composition comprising the compound represented by Chemical Formula 1 of the present invention can be used in a polymerizable composition for producing an optical element. An optical element produced from a polymerizable composition comprising the isocyanate composition exhibits high transparency and low yellowness, an excellent glass transition temperature, and improved impact resistance.

[0030]

[0031] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprise," "include," or "have" indicate the presence of a feature, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, steps, components, or combinations thereof.

[0032] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated and described in detail below. However, this is not intended to limit the present invention to specific disclosed forms, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0033] Hereinafter, the present invention will be described in detail.

[0034]

[0035] compound

[0036] The present invention provides a compound represented by the above chemical formula 1.

[0037] The compound represented by the above chemical formula 1 may be included as an additive in an isocyanate composition including an isocyanate compound such as xylylene diisocyanate.

[0038] In a preferred embodiment, n1 to n3 can each independently be an integer from 1 to 3.

[0039] In a preferred embodiment, R1 to R6 can each independently be hydrogen, deuterium, tritium, or methyl.

[0040] In a preferred embodiment, R1 to R6 can be the same.

[0041] In a preferred embodiment, all of R1 to R6 can be hydrogen.

[0042] In a preferred embodiment, n1 to n3 may all be 1, and R1 to R6 may all be hydrogen. In this case, chemical formula 1 may be represented by the following chemical formula 1-1:

[0043] [Chemical Formula 1-1]

[0044]

[0045] The compound represented by the above chemical formula 1 may be, for example, represented by the following chemical formula 1-1-a:

[0046] [Chemical Formula 1-1-a]

[0047]

[0048] The compound represented by the above chemical formula 1 can be prepared, for example, through a reaction represented by the following reaction formula 1. However, the method for preparing the compound represented by the chemical formula 1 is not limited to the following:

[0049] [Reaction Formula 1]

[0050]

[0051] In the above reaction formula 1, n1 to n3 and R1 to R6 are as defined in chemical formula 1.

[0052] The reaction of the above reaction scheme 1 can proceed under conditions that remove by-product water. For example, it can proceed using a Dean-Stark trap or by adding a dehydrating agent capable of removing water (e.g., MgSO4, Na2SO4, molecular sieve, etc.).

[0053]

[0054] Isocyanate composition

[0055] The isocyanate composition of the present invention comprises xylylene diisocyanate (XDI) and a compound represented by the above chemical formula 1, and the content of the compound represented by the above chemical formula 1 satisfies a range of more than 0 ppm and less than or equal to 1000 ppm.

[0056] Specifically, the above xylylene diisocyanate may be at least one selected from the group consisting of 1,2-xylylene diisocyanate (o-xylylene diisocyanate, o-XDI), 1,3-xylylene diisocyanate (m-xylylene diisocyanate, m-XDI), and 1,4-xylylene diisocyanate (p-xylylene diisocyanate, p-XDI).

[0057] Preferably, the xylylene diisocyanate may be m-XDI.

[0058] The above xylylene diisocyanate can be prepared using a commercially available product or by a preparation method including a step of reacting xylylene diamine or a xylylene diamine salt with phosgene. The xylylene diisocyanate preferably has a purity of 97.7 wt% or more, 98.0 wt% or more, 98.3 wt% or more, 99.0 wt% or more, or 99.2 wt% or more. The purity of the xylylene diisocyanate may be 100 wt%, or 99.9 wt% or less, or 99.8 wt% or less.

[0059] The content of the xylylene diisocyanate in the isocyanate composition of the present invention may be 97.7 wt% or more, 98.0 wt% or more, 98.3 wt% or more, 99.0 wt% or more, or 99.2 wt% or more.

[0060] In one embodiment, the remainder of the isocyanate composition, excluding the compound represented by the chemical formula 1, may be xylylene diisocyanate. Alternatively, the xylylene diisocyanate may be included in an amount of 99.9 wt% or less, or 99.8 wt% or less, of the isocyanate composition.

[0061] An isocyanate composition comprising a compound represented by Chemical Formula 1 as described above, but having a content of 0 ppm to 1000 ppm, exhibits little clouding even when stored at low temperatures. In addition, a poly(thio)urethane lens manufactured using such an isocyanate composition exhibits high transparency, low yellowness, a high glass transition temperature (Tg), and improved impact resistance, and thus can be suitably used as a high-quality optical element.

[0062] To secure these effects, the content of the compound represented by the above chemical formula 1 in the isocyanate composition may be 0.1 ppm or more, 0.2 ppm or more, 0.3 ppm or more, or 0.5 ppm or more, and 1000 ppm or less, 800 ppm or less, 500 ppm or less, or 300 ppm or less.

[0063] If the content of the compound in the above isocyanate composition exceeds 1000 ppm, the storage stability of the isocyanate composition deteriorates, and the yellowness of the poly(thio)urethane lens increases and the transparency decreases. In addition, an isocyanate composition having a content of the compound of less than 0.1 ppm cannot exhibit the effect of improving the glass transition temperature and impact resistance during the production of poly(thio)urethane.

[0064] Meanwhile, the above isocyanate composition may further include at least one selected from the group consisting of chloromethylbenzyl isocyanate, isocyanomethylbenzaldehyde, and isocyanomethylbenznitrile, and the content thereof may be 0.01 to 0.5 parts by weight based on 100 parts by weight of the isocyanate composition.

[0065] When the composition further comprises at least one additional substance selected from the group consisting of chloromethylbenzyl isocyanate, isocyanomethylbenzaldehyde, and isocyanomethylbenznitrile, the content of xylylene diisocyanate in the isocyanate composition may be the remainder excluding the additional substance and the compound of the chemical formula 1.

[0066]

[0067] polymeric composition

[0068] The isocyanate composition of the present invention described above can be used as a raw material for producing poly(thio)urethane, and the poly(thio)urethane produced in this way exhibits improved impact resistance and excellent transparency.

[0069] Accordingly, according to one embodiment of the present invention, a polymerizable composition comprising the isocyanate composition and a polyol and / or polythiol component is provided.

[0070] The above polymerizable composition has high transparency and excellent impact strength, and can be suitably used as a high-quality optical material.

[0071] The description of the isocyanate composition included in the above polymerizable composition is as described above.

[0072] The polyol included in the above polymerizable composition is a compound having two or more hydroxyl groups, and compounds commonly used in the production of polyurethane can be used without limitation. For example, the polyol includes dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 2-methyl-2,3-butanediol, 1,6-hexanediol, 1,2-hexanediol, etc.; trihydric alcohols such as glycerol, trimethylolethane, trimethylolpropane (TMP), etc.; tetrahydric alcohols such as diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol, etc.; pentahydric alcohols such as L-arabinitol, ribitol, xylitol, etc.; hexahydric alcohols such as D-glucitol, D-mannitol, galactitol, etc.; heptahydric alcohols such as trehalose, etc. Examples include octahydric alcohols such as sucrose and maltose, or low molecular weight polyols such as polyalkylene oxides having a number average molecular weight of 60 to 400.

[0073] Among these, diethylene glycol, glycerol, trimethylolethane, trimethylolpropane or a mixture thereof may be used, and more specifically, it may be preferable to use a trihydric alcohol such as glycerol, trimethylolpropane or trimethylolethane alone, or to use the trihydric alcohol in combination with another polyol.

[0074] The above polythiol is a compound having two or more mercapto groups, and compounds used in the production of polythiourethane can be used without limitation. For example, aliphatic polythiols such as 2,3-bis(2-sulfanylethylsulfanyl)propane-1-thiol, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithianedecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithianedecane, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithianedecane can be used alone or in combination of two or more, but are not limited thereto.

[0075] Meanwhile, the molar ratio of the hydroxyl group (-OH) or mercapto group (-SH) to the isocyanate group (-NCO) in the polymerizable composition (i.e., the molar ratio of OH / NCO or SH / NCO) may be 0.5 or more, or 0.8 or more, and 3.0 or less, or 2.0 or less.

[0076] The above polymerizable composition may further include compounds such as an internal release agent, an ultraviolet absorber, a polymerization initiator, a heat stabilizer, a color corrector, a chain extender, a crosslinking agent, a light stabilizer, an antioxidant, and a filler, as needed.

[0077] For example, the polymerizable composition may further include a polymerization initiator, an internal release agent, and an ultraviolet absorber.

[0078] The polymerization initiator may be an amine-based, phosphorus-based, organotin-based, organocopper-based, organogallium-based, organozirconium-based, organozinc-based, organoaluminum-based, etc. The polymerization initiator may be included in an amount of 0.001 to 0.1 parts by weight per 100 parts by weight of the polymerizable composition.

[0079] The internal release agent may be selected from among fluorine-based nonionic surfactants having a perfluoroalkyl group, a hydroxyalkyl group, or a phosphate ester group; silicone-based nonionic surfactants having a dimethylpolysiloxane group, a hydroxyalkyl group, or a phosphate ester group; quaternary alkyl ammonium salts, such as trimethyl cetyl ammonium salt, trimethylstearyl, dimethylethyl cetyl ammonium salt, triethyldodecyl ammonium salt, trioctylmethyl ammonium salt, and diethylcyclohexadodecyl ammonium salt; and phosphoric acid ester compounds such as acidic phosphoric acid esters, which may be used alone or in combination of two or more. Preferably, a phosphoric acid ester compound may be used. The internal release agent may be used in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the polymerizable composition.

[0080] Examples of the above ultraviolet absorbent include benzotriazole compounds (specifically, Tinuvin 571, Tinuvin 213, Tinuvin 234, and Tinuvin P (all manufactured by BASF)), formamidine compounds (specifically, Zikasorb R, Zikasorb BS, ZIKA-FA02, ZIKA-FUA, ZIKA-FUV, ZIKA-UVS3, and ZIKA-UVS4 (all manufactured by ZIKO)), and Biosorb 583 (manufactured by Sakai Chemical Industry Co., Ltd.). The ultraviolet absorbent may be used in an amount of 0.01 to 1 part by weight per 100 parts by weight of the polymerizable composition.

[0081] An optical element comprising a polymer polymerized with a polymerizable composition comprising the isocyanate composition of the present invention described above exhibits high transparency and improved impact resistance. Accordingly, the optical element can be usefully used as an eyeglass lens, a camera lens, an adhesive requiring transparency, a resin, and the like.

[0082]

[0083] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0084]

[0085] <Example>

[0086] Example 1

[0087] (1) Preparation of compound 1-1-a

[0088]

[0089] 3-(isocyanatomethyl)benzylamine 324.4 mg (2.0 mmol) and 3-(isocyanatomethyl)benzaldehyde 322.4 mg (2.0 mmol) were added to 10 ml of anhydrous methylene chloride solvent and stirred for 15 minutes. Then, 710.2 mg (5 mmol) of Na2SO4 was added and stirred at room temperature for 4 hours. After the reaction was completed, Na2SO4 was filtered off, and the solvent was removed under reduced pressure. The compound 1-1-a thus obtained was confirmed through GC-MS analysis (molecular formula: C 18 H 15 N3O2(305.34))

[0090]

[0091] (2) Preparation of xylylene diisocyanate composition

[0092] A xylylene diisocyanate composition was prepared by adding the compound 1-1-a to m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)) so that the mass thereof was 0.5 ppm with respect to the total mass of the composition.

[0093]

[0094] (3) Preparation of polymerizable composition

[0095] 62.4 g of the xylylene diisocyanate composition prepared above, 0.16 g of ZELEC™ UN (manufactured by Stepan) as an internal release agent, and 0.80 g of Tinuvin® 329 (manufactured by BASF) as an ultraviolet absorber were mixed in a flask at room temperature with stirring for about 20 minutes.

[0096] 0.024 g of dibutyltin dichloride was added to the above mixture and stirred for 10 minutes. Then, 57.6 g of 2,3-bis(2-sulfanyl ethyl sulfanyl)propane-1-thiol as a multifunctional thiol compound was added, and the mixture was degassed under 5 mbar conditions and stirred for 1 hour to prepare a polymerization composition.

[0097]

[0098] (4) Manufacturing of optical lenses

[0099] The polymerizable composition thus prepared was filtered through a 1 μm PTFE filter and then injected into a mold comprising a glass mold and tape. The mold was placed in an oven, and the temperature was gradually increased from 10°C to 120°C, during which time polymerization was performed for 20 hours. After polymerization, the mold was removed from the oven and released to obtain a plastic optical lens. The resulting lens was annealed at 120°C for 6 hours.

[0100]

[0101] Example 2

[0102] A xylylene diisocyanate composition was prepared by adding the compound 1-1-a to m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)) so that the mass thereof was 30 ppm with respect to the total mass of the composition.

[0103] Thereafter, a polymerizable composition and an optical lens were manufactured using the same method as in Example 1.

[0104]

[0105] Example 3

[0106] A xylylene diisocyanate composition was prepared by adding the compound 1-1-a to m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)) so that the mass thereof was 240 ppm with respect to the total mass of the composition.

[0107] Thereafter, a polymerizable composition and an optical lens were manufactured using the same method as in Example 1.

[0108]

[0109] Example 4

[0110] A xylylene diisocyanate composition was prepared by adding the compound 1-1-a to m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)) so that the mass thereof was 500 ppm with respect to the total mass of the composition.

[0111] Thereafter, a polymerizable composition and an optical lens were manufactured using the same method as in Example 1.

[0112]

[0113] Comparative Example 1

[0114] The compound 1-1-a was added to m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)) so that the mass thereof was 1100 ppm with respect to the total mass of the composition, thereby obtaining a xylylene diisocyanate composition.

[0115] Thereafter, a polymerizable composition and an optical lens were manufactured using the same method as in Example 1.

[0116]

[0117] Comparative Example 2

[0118] The compound 1-1-a was added to m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)) so that the mass thereof was 1500 ppm with respect to the total mass of the composition, thereby obtaining a xylylene diisocyanate composition.

[0119] Thereafter, a polymerizable composition and an optical lens were manufactured using the same method as in Example 1.

[0120]

[0121] Comparative Example 3

[0122] A polymerizable composition and an optical lens were prepared in the same manner as in Example 1 using m-xylylene diisocyanate (TOKYO CHEMICAL INDUSTRY CO.LTD., purity >98.0% (GC)).

[0123]

[0124] <Experimental Example>

[0125] (1) Component analysis of isocyanate composition

[0126] The content of the compound of chemical formula 1 in the isocyanate composition was analyzed using gas chromatography (GC). The analysis conditions were as follows.

[0127] GC system: Agilent 7890A 5975C

[0128] Column: DB-17MS (30 m * 0.25 mm * 0.25 μm)

[0129] Carrier gas: Nitrogen (1.0 mL / min)

[0130] Sample injection volume: 1μl

[0131] Inlet temperature: 250 ℃

[0132] Detector temperature: 280 ℃

[0133] Oven temperature: Increase from 80 ℃ to 160 ℃ at a rate of 5 ℃ / min, maintain for 8 minutes, then increase again to 280 ℃ at a rate of 20 ℃ / min, maintain for 18 minutes, and then analyze.

[0134] Splitby: Pulsed Splitless Method

[0135] Detection method: SIM (monitoring ions: m / z 146, 305)

[0136]

[0137] (2) Yellowness (YI) and haze of optical lenses

[0138] The yellowness index (YI) and haze (%) of an optical lens manufactured to a thickness of 9.3 mm were measured using the method described below. The smaller the YI and haze values, the better the color and transparency of the lens are evaluated to be.

[0139] Equipment: Ultrascan Pro, HunterLab

[0140] Light source: D65 / 10

[0141] Measurement standard: ASTM E313

[0142]

[0143] (3) Glass transition temperature (Tg) of optical lenses

[0144] The glass transition temperature (Tg) of the optical lens was measured by the penetration method (50 g load, pin tip 0.5 mmФ, heating rate 10°C / min) using a thermomechanical analyzer (TMA Q400, TA instruments).

[0145]

[0146] (4) Impact resistance of optical lenses

[0147] A 350 g steel ball at 22°C was dropped from a height of 127 cm onto the front surface of a 2 mm thick lens. The above experiment was performed on each of 30 lenses manufactured from the same composition, and if no lens was broken, the impact resistance was judged to be excellent (O), if 1 or 2 lenses were broken or cracked, the impact resistance was judged to be average (△), and if 3 or more lenses were broken, the impact resistance was judged to be poor (X).

[0148]

[0149] The results of the above experiment are summarized in Table 1 below.

[0150]

[0151] Chemical Formula 1 Compound Content (ppm) YI Haze (%) Tg (℃) Impact Resistance Example 10.5 5.00 0.2 10 1.4 O Example 2 3 05.07 0.3 10 1.6 O Example 3 2 4 05.11 0.4 10 2.1 O Example 4 5 005.12 0.4 10 3.2 O Comparative Example 1 1 1 005.28 0.9 10 4.4 O Comparative Example 2 1 5 005.36 1.5 10 4.7 O Comparative Example 305.00 0.3 10 0.9 △

[0152]

[0153] Referring to Table 1 above, it can be confirmed that the optical lenses manufactured using the isocyanate compositions of Examples 1 to 4, which include the compound represented by Chemical Formula 1 but have a content of 1000 ppm or less, have low yellowness and high transparency, and have a high glass transition temperature and excellent impact resistance compared to Comparative Example 3, which does not include the compound represented by Chemical Formula 1.

[0154] However, it can be confirmed from Comparative Examples 1 and 2 that when the compound represented by Chemical Formula 1 exceeds 1000 ppm, the yellowness and turbidity of the optical lens increase.

[0155] Through the above results, it can be confirmed that an optical lens having excellent glass transition temperature and impact resistance while having less clouding and yellowing can be provided by using an isocyanate composition including a compound represented by Chemical Formula 1 but satisfying a content of more than 0 ppm and less than 1000 ppm.

Claims

1. A compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, n1 to n3 are each independently integers from 0 to 6, R1 to R6 are each independently hydrogen, deuterium, tritium, or C 1-6 It's alkyl.

2. In paragraph 1, n1 to n3 are each independently an integer from 1 to 3, compound.

3. In paragraph 1 or 2, R1 to R6 are all hydrogen, compound.

4. In paragraph 1, The above compound is represented by the following chemical formula 1-1: compound: [Chemical Formula 1-1] .

5. An isocyanate composition comprising xylylene diisocyanate and a compound represented by the following chemical formula 1, wherein the content of the compound represented by the following chemical formula 1 is more than 0 ppm and less than or equal to 1000 ppm: [Chemical Formula 1] In the above chemical formula 1, n1 to n3 are each independently integers from 0 to 6, R1 to R6 are each independently hydrogen, deuterium, tritium, or C 1-6 It's alkyl.

6. In paragraph 5, An isocyanate composition having a content of the compound represented by the chemical formula 1 of 0.1 ppm to 1000 ppm.

7. In paragraph 5 or 6, An isocyanate composition further comprising at least one selected from the group consisting of chloromethylbenzyl isocyanate, isocyanomethylbenzaldehyde and isocyanomethylbenznitrile.

8. An isocyanate composition according to any one of claims 5 to 7; and A polymerizable composition comprising a polyol and / or polythiol component.

9. In paragraph 8, A polymerizable composition, wherein the polyol and / or polythiol component comprises one or more of 2,3-bis(2-sulfanylethylsulfanyl)propane-1-thiol, 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.

10. In clause 8 or 9, A polymerizable composition further comprising a polymerization initiator, an internal release agent, and an ultraviolet absorber.

11. An optical element comprising a polymer polymerized with the polymerizable composition of any one of claims 8 to 10.

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