Method for rapid curing of a polythiourethane-based substrate using a delayed-action catalyst

Abstract

The present invention relates to a method for rapidly curing a polythiourethane-based transparent casting substrate. In a preferred embodiment, the method includes preparing a first component A containing a polythiourethane prepolymer A1 having isocyanate end groups or isothiocyanate end groups, preparing a second component B containing a polythiourethane prepolymer B1 having thiol end groups, mixing the first component A and the second component B together, filling the resulting mixture into the molding cavity of a casting mold assembly, and curing the mixture to obtain a transparent substrate. At least one heat-activatable latent catalyst is added in the process before the curing step 4), and then the catalyst is activated to promote the polymerization reaction for forming the polythiourethane-based transparent substrate.

Description

Technical Field

[0001] The present invention generally relates to a method for producing a polythiourethane-based substrate having a refractive index of medium or high refractive index, preferably at least 1.52, more preferably at least 1.54, more preferably at least 1.6, and even more preferably at least 1.67, particularly an optical substrate such as an ophthalmic lens, with a short curing cycle.

Background Art

[0002] Ophthalmic lenses produced from polythiourethane-based substrates are typically manufactured by a method including mixing appropriate monomers such as a mixture of a polyisocyanate and a polythiol in a tank, adding a catalyst and additives, filling a molding cavity with this liquid mixture of monomers, polymerizing the monomer mixture, and then recovering the polymerized polythiourethane-based substrate from the mold. The mixture usually undergoes a heat cycle in an oven, typically for 20 hours.

[0003] A rapid curing process is highly desirable compared to a normal process because it dramatically improves productivity due to the short residence time in the curing oven, gives a better yield of complex and demanding lens shapes due to the lower shrinkage rate of the final polymerizable mixture compared to the mixture obtained directly from the monomers, has excellent compatibility with the adhesive of the tape used in the mold assembly, and reduces energy consumption during the polymerization cycle.

[0004] It is known that using oligomers instead of monomers shortens the time required for curing the polymerizable composition poured into the mold assembly. The monomers first undergo a preliminary reaction to form oligomers, which are then blended with a catalyst that provides a high overall reactivity, even in very small amounts or via an in-line mixing device, and then poured into the mold assembly, which typically undergoes a short polymerization cycle of several hours.

[0005] In this regard, US Patent Application Publication No. 2003 / 125410 discloses a method for rapidly curing a polythiourethane transparent casting substrate, which method comprises: 1) preparing a first component A comprising a polythiourethane prepolymer having isocyanate or isothiocyanate end groups; 2) preparing a second component B comprising a polythiourethane prepolymer having thiol end groups; 3) mixing the first component A and the second component B together and filling the resulting mixture into the molding cavity of a casting mold assembly; 4) curing the mixture in the presence of a highly reactive catalyst to obtain a transparent solid substrate, typically shortening the curing time of the polymerizable composition significantly within 2 hours. It includes.

[0006] If the viscosity is controlled, a part of the available bond-forming energy is already released during oligomer formation (pre-polymerization), and the formation of local hot spots in the final polymerizable mixture is limited. Therefore, batch mixing of such mixtures is essentially safer than the normal process from monomers. Using prepolymers enables a stable and constant reaction. Known catalysts for polythiourethane synthesis are dibutyltin dichloride or a mixture of KSCN and 18-crown-6. However, when all components are mixed together, they react to form a gel in less than 10 minutes at room temperature.

[0007] In the applications of European Patent No. 3916470 and European Patent No. 3919967, another approach for rapidly curing polythiourethane optical materials is selected, which combines the use of monomers and prepolymers in the presence of a polymerization catalyst (typically a basic catalyst).

[0008] However, the main technical problem of the rapid curing process described in the prior art is the short pot life of the polymerizable mixture. This results in a major constraint in the mixing / filling step because only a short time is allowed to achieve sufficient mixing of the very viscous prepolymer before gelling. Therefore, a polymerizable composition having a longer pot life, for example a polymerizable mixture with a longer time range until it reaches a viscosity that cannot be handled (mixed / filled), offers a great advantage in extending the mixing time and is particularly important when the mixture is highly viscous. Furthermore, such mixtures can advantageously be processed in batch form in the same way as normal processes starting from monomers. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0009] Accordingly, an object of the present invention is to provide a method for rapidly curing a polythiourethane-based transparent casting substrate that improves the drawback of the conventional method of having a short pot life of the polymerizable mixture.

[0010] Another object of the present invention is to provide a method for rapidly curing a polythiourethane-based transparent casting substrate that is substantially free of optical defects, particularly bubbles and / or streak-like scratches resulting from the polymerization process.

[0011] The inventors have found that by using specific catalysts that are blended in an inert form and essentially show no catalytic action in the polymerizable mixture but subsequently induce the formation of the final polythiourethane-based polymer, the reactivity of the polymerizable mixture can be minimized. These catalysts allow better control of the polymerization reaction.

[0012] The present invention is a method for rapidly curing a polythiourethane-based transparent casting substrate that can be used in the manufacture of optical articles such as ophthalmic lenses, 1) Preparing a first component A containing a polythiourethane prepolymer A1 having an isocyanate terminal group or an isothiocyanate terminal group of the formula -NCX (where X is O or S) from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer; 2) Preparing a second component B containing a polythiourethane prepolymer B1 having a thiol terminal group from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer; Or 1) Preparing a first component A containing at least one polyisocyanate monomer or polyisothiocyanate monomer; 2) Preparing a second component B containing a polythiourethane prepolymer B1 having a thiol terminal group from a polythiol monomer and a polyisocyanate monomer or polyisothiocyanate monomer; Or 1) Preparing a first component A containing a polythiourethane prepolymer A1 having an isocyanate terminal group or an isothiocyanate terminal group of the formula -NCX (where X is O or S) from a polythiol monomer and a polyisocyanate monomer or polyisothiocyanate monomer; 2) Preparing a second component B containing at least one polythiol monomer; 3) Mixing the first and second components A and B together and filling the resulting mixture into the molding cavity of a casting mold assembly; 4) Curing the mixture to obtain a polythiourethane-based transparent substrate, and 5) Recovering the polythiourethane-based transparent substrate from the casting mold assembly comprising providing a method in which at least one heat-activatable latent catalyst is used in the process before the curing step 4), and then the catalyst is activated.

[0013] In the present invention, at least one heat-activatable latent catalyst is added in the process before the curing step 4), and then the catalyst is activated to promote the polymerization reaction to form a polythiourethane-based transparent substrate.

[0014] The method of the present invention provides several advantages in addition to those described above.

[0015] The reactivity of the finally formulated polymerizable mixture is essentially the same as that of the blend without catalyst, with a low risk of clogging due to local gelation and can be flowed through a pipe to a filling station.

[0016] All components containing the catalyst can be mixed together for a time corresponding to a very high level of mixing state, reducing non-uniformity and optical defects such as streaky scratches.

Embodiments for Carrying Out the Invention

[0017] The substrate of the present invention is an organic glass substrate made from a thermosetting resin. The polymer matrix of the substrate is obtained from a material composition (the "substrate composition") containing at least one, preferably at least two polymerizable prepolymers.

[0018] The substrate is preferably a substrate for an optical article, more preferably a substrate for an optical lens. The optical article is preferably an ophthalmic lens, such as a plastic ophthalmic lens.

[0019] In this specification, unless otherwise specified, a substrate is understood to be transparent when the observation of an image through the substrate is perceived without a significant loss of contrast, that is, when the formation of an image through the substrate is obtained without adversely affecting the quality of the image. This definition of the term "transparent" can be applied to all objects so modified in the description, unless otherwise specified.

[0020] The term "ophthalmic lens" is used to mean a lens adapted to an eyeglass frame to protect the eye and / or correct vision. The lens can be selected from an afocal, single-focus, bifocal, trifocal, progressive lens, Fresnel lens, or other types of lenses having a discontinuous surface. Although the ophthalmic optical system is a preferred field of the present invention, it will be understood that the present invention can be applied to other types of optical elements, such as lenses for optical instruments, particularly filters for photography or astronomy, optical aiming lenses, ophthalmic visors, optical systems of lighting systems, screens, plate glass, etc.

[0021] When the optical article is an optical lens, it may have one or more functional coatings on the front principal surface, the rear principal surface, or both. As used herein, the rear surface of the substrate is intended to mean the surface closest to the wearer's eye when the article is in use. This is generally a concave surface. Conversely, the front surface of the substrate is the surface farthest from the wearer's eye when the article is in use. This is generally a convex surface. The optical article can also be a planar article.

[0022] The substrate should be understood to mean, in the context of the present invention, an uncoated substrate, and generally has two principal surfaces. The substrate can be, in particular, an optically transparent material having the shape of an ophthalmic lens intended to be attached to an optical article, such as glass. In this context, the term "substrate" is understood to mean the base component material of an optical lens, more specifically an ophthalmic lens. This material can function as a support for a stack of one or more coatings or layers.

[0023] The refractive index of the polythiourethane-based transparent substrate is preferably 1.52 or more, more preferably 1.54 or more, still more preferably 1.56 or more, still more preferably 1.58 or more, still more preferably 1.60 or more, and even more preferably 1.65 or more, and this is preferably 1.80 or less, more preferably 1.70 or less, and even more preferably 1.67 or less. Unless otherwise specified, the refractive index referred to in this application is expressed at 25 °C at a wavelength of 550 nm.

[0024] The rapid-curing polymerizable composition for obtaining a polythiourethane-based material is composed of two main components.

[0025] In the first embodiment of the present invention, the first component A is composed of a polythiourethane prepolymer A1 having an isocyanate (NCO) terminal group or an isothiocyanate (NCS) terminal group. The second component B is composed of a polythiourethane prepolymer B1 having a thiol (SH) terminal group.

[0026] In step 1) of the first and third embodiments of the present method, a first component A containing a polythiourethane prepolymer A1 having an isocyanate terminal group or an isothiocyanate terminal group is prepared, which is prepared from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer, and the latter is used in excess. Therefore, the first component A contains an oligomer and unreacted initial monomers.

[0027] In step 2) of the first and second embodiments of the present method, a second component B containing a polythiourethane prepolymer B1 having a thiol terminal group is prepared, which is prepared from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer, and the former is used in excess. Therefore, the second component B contains an oligomer and unreacted initial monomers.

[0028] In the second embodiment of the present invention, the first component A is composed of at least one polyisocyanate monomer or polyisothiocyanate monomer. The second component B is composed of a polythiolurethane prepolymer B1 having a thiol (SH) terminal group.

[0029] In the third embodiment of the present invention, the first component A is composed of a polythiolurethane prepolymer A1 having an isocyanate (NCO) terminal group or an isothiocyanate (NCS) terminal group. The second component B is composed of at least one polythiol monomer.

[0030] In contrast to prior art processes that use only iso(thio)cyanate monomers or thiol monomers, at least one prepolymer is used in the present invention.

[0031] A prepolymer means a polymer or oligomer containing prepolymer molecules. A prepolymer molecule means a polymer or oligomer molecule that can enter into further polymerization via reactive (polymerizable) groups, thereby contributing two or more monomer units to at least one chain of the final polymer. This is usually formed from two or more different monomers.

[0032] The polythiolurethane prepolymer A1 having an isocyanate terminal group or an isothiocyanate terminal group is prepared by reacting at least one polyisocyanate monomer or polyisothiocyanate monomer and at least one polythiol monomer in a ratio such that the molar ratio of isocyanate group or isothiocyanate group to thiol group NCX / SH (X is O or S) is preferably in the range of 3:1 to 30:1, preferably without a catalyst.

[0033] The polythiourethane prepolymer B1 having a thiol terminal group is prepared by reacting at least one polyisocyanate monomer or polyisothiocyanate monomer with at least one polythiol monomer at a ratio such that the molar ratio of thiol groups to isocyanate groups or isothiocyanate groups SH / NCX (X is O or S) is preferably in the range of 3:1 to 30:1, preferably without a catalyst.

[0034] The polythiol compound and polyisocyanate compound or polyisothiocyanate compound used in the preparation of the polythiourethane prepolymer A1 or B1 are regarded as monomers herein even if they are oligomers.

[0035] Polyisocyanate means a compound containing at least two isocyanate groups, in other words, diisocyanate, triisocyanate, etc. A polyisocyanate prepolymer may be used. The polyisocyanate may be any suitable polyisocyanate having two or more, preferably two or three isocyanate functional groups.

[0036] The polyisocyanate can be selected from aliphatic, aromatic, alicyclic, or heterocyclic polyisocyanates, and mixtures thereof.

[0037] Polyisothiocyanate is defined in the same manner as the above polyisocyanate by replacing the "isocyanate" group with an "isothiocyanate" group.

[0038] Preferred polyisocyanate monomers or isothiocyanate monomers have the following formula:

Chemical formula

[0039] The polyisocyanate of the present invention is preferably a diisocyanate. Among the available diisocyanates, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, paraphenylene diisocyanate, xylylene diisocyanate, biphenyl-diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, 2,2,4-trimethylhexane-1,6-diisocyanate, lysine methyl ester diisocyanate, bis(isocyanatoethyl) fumarate, isophorone diisocyanate (IPDI), ethylene diisocyanate, dodecane-1,12-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene-2,4-diisocyanate, hexahydrotoluene-2,6-diisocyanate, hexahydrophenylene-1,3-diisocyanate, hexahydrophenylene-1,4-diisocyanate, perhydrodiphenylmethane-2,4'-diisocyanate, perhydrodiphenylmethane-4,4'-diisocyanate (or bis-(4-isocyanatocyclohexyl)methane, or 4,4'-dicyclohexylmethane diisocyanate), bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, 2,5 (or 2,6)-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, and mixtures thereof can be mentioned.

[0040] Other non-limiting examples of polyisocyanates are isocyanurates from isophorone diisocyanate and 1,6-hexamethylene diisocyanate, both of which are commercially available. Further polyisocyanates suitable for the present invention are described in detail in WO 98 / 37115, WO 2014 / 133111, or EP 1877839.

[0041] The polythiols that can be used in the present invention are defined as compounds containing at least two sulfhydryl (mercapto) groups, in other words dithiols, trithiols, tetrithiols, etc. Polythiol prepolymers may be used. The polythiol may be any suitable polythiol having two or more, preferably two or three thiol functional groups.

[0042] Preferred polythiol monomers and / or oligomers suitable for the present invention include trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), trimethylolethane tris(2-mercaptoacetate), trimethylolethane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), bis(mercaptomethyl) sulfide, bis(mercaptomethyl) disulfide, bis(mercaptoethyl) sulfide, bis(mercaptoethyl) disulfide, bis(mercaptopropyl) sulfide, bis(mercaptopropyl) disulfide, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol, 4,8(or 4,7 or 5,7)-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis[(2-mercaptoethyl)thiomethyl]-1,4-dithiane, 1-(1'-mercaptoethylthio)-2,3-dimercaptopropane, 1-(2'-mercaptopropylthio)-2,3-dimercaptopropane, 1-(3'-mercaptopropylthio)-2,3-dimercaptopropane, 1-(4'-mercapbutylthio)-2,3-dimercaptopropane, 1-(5'-mercapentylthio)-2,3-dimercaptopropane, 1-(6'-mercaphexylthio)-2,3-dimercaptopropane, 1,2-bis-(4'-mercapbutylthio)-3-mercaptopropane, 1,2-bis-(5'-mercapentylthio)-3-mercaptopropane, 1,2-bis-(6'-mercaphexylthio)-3-mercaptopropane, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris-(3'-mercaptopropylthio)propane, 1,2,3-tris-(2'-mercaptoethylthio)propane, 1,2,3-tris-(4'-mercapbutylthio)propane, 1,2,3-tris-(6'-mercaphexylthio)propane, methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,Examples of aliphatic polythiols include 2-propanedithiol, 1,6-hexanedithiol-1,2,3-propanetrithiol, and 1,2-bis(2'-mercaptoethylthio)-3-mercaptopropane. Further examples of polythiols are shown in the following formula, or can be found in WO 2014 / 133111 pamphlet, EP 394495 specification, US 4775733 specification, or EP 1877839 specification:

Chem.

[0043] Preferred embodiments include the combination of xylylene diisocyanate and pentaerythritol tetrakis(3-mercaptopropionate); the combination of xylylene diisocyanate and 2,3-bis((2-mercaptoethyl)thio)-1-propanedithiol; the combination of 2,5(or 2,6)-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, pentaerythritol tetrakis(3-mercaptopropionate) and 2,3-bis((2-mercaptoethyl)thio)-1-propanedithiol; the combination of xylylene diisocyanate and 4,8(or 4,7 or 5,7)-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane; the combination of dicyclohexylmethane diisocyanate and 4,8(or 4,7 or 5,7)-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane; or the combination of bis(2,3-epithiopropyl) disulfide and 4,8(or 4,7 or 5,7)-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane. The most preferred polythiol is 2,3-bis((2-mercaptoethyl)thio)-1-propanedithiol shown below:

Chem.

[0044] Preferably, the polythiol has a viscosity of 1 Pa·s or less at 25°C, more preferably 5×10 -1 Pa·s or less, even more preferably 2.5×10 -1 Pa·s or less, even more preferably 2×10 -1 Pa·s or less, even more preferably 10 -1 Pa·s or less, still more preferably 0.5×10 -1 Pa·s or less.

[0045] According to an embodiment of the present invention, components A and B are prepared by polymerizing a mixture of at least one polyisocyanate and / or at least one polyisothiocyanate monomer in a required amount, at least one polythiol monomer, and an optional polyol monomer or polyamine monomer. Typically, components A and B can be prepared by conventional thermal polymerization including induction heating and infrared heating.

[0046] The amounts of the polyisocyanate monomer or polyisothiocyanate monomer and the polythiol monomer in the reaction medium are preferably such that for the preparation of the polythiourethane prepolymer A1, the molar ratio of the NCX / SH groups of the polyisocyanate monomer or polyisothiocyanate monomer and the mixture of the polythiol monomer is in the range of 3:1 to 30:1, preferably 6:1 to 10:1, and / or for the preparation of the polythiourethane prepolymer B1, the molar ratio of the SH / NCX groups of the polyisocyanate monomer or polyisothiocyanate monomer and the mixture of the polythiol monomer is in the range of 3:1 to 30:1, preferably 6:1 to 10:1, and are adjusted in each case, where X in the formula is O or S.

[0047] In one embodiment, both components A and B are prepared without using a catalyst system, whereby the polymerization reaction can be better controlled and a prepolymer with high stability over time can be obtained. However, it can also be prepared using the above-described catalyst or catalyst system.

[0048] Generally, in the first embodiment of the present invention, prepolymer A1 and prepolymer B1 are contained in the mixture in an amount such that the molar ratio of NCX groups to SH groups is 0.8 to 1.2, preferably 1.

[0049] Generally, in the second embodiment of the present invention, at least one polyisocyanate monomer or polyisothiocyanate monomer and prepolymer B1 are contained in the mixture in an amount such that the molar ratio of NCX groups to SH groups is 0.8 to 1.2, preferably 1.

[0050] Generally, in the third embodiment of the present invention, prepolymer A1 and at least one polythiol monomer are contained in the mixture in an amount such that the molar ratio of NCX groups to SH groups is 0.8 to 1.2, preferably 1.

[0051] Generally, in the second embodiment of the present invention, the polyisocyanate or polyisothiocyanate of component A and prepolymer B1 are contained in the mixture in an amount such that the molar ratio of NCX groups to SH groups is 0.8 to 1.2, preferably 1.

[0052] Generally, in the third embodiment of the present invention, prepolymer A1 and the polythiol of component B are contained in the mixture in an amount such that the molar ratio of NCX groups to SH groups is 0.8 to 1.2, preferably 1.

[0053] The preparation of prepolymer B1 having thiol end groups has already been described in U.S. Patent No. 5,908,876. Component B of the present invention can be prepared using a similar process.

[0054] When component A of the present invention contains polythiolurethane prepolymer A1, it can be prepared in a similar manner, but in order to obtain polythiolurethane prepolymer A1 having isocyanate end groups or isothiocyanate end groups, it can be prepared using the required ratio of polyisocyanate or polyisothiocyanate and polythiol monomer.

[0055] The mixture of polythiol / polyiso(thio)cyanate for obtaining prepolymer A1 may contain at least one polyol of 90% by weight or less. Preferably, the mixture may contain at least one polyol of 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less. It is also preferable not to use a polyol. Polyiso(thio)cyanate means polyisocyanate or polyisothiocyanate.

[0056] The mixture of polythiol / polyiso(thio)cyanate for obtaining prepolymer B1 may contain at least one polyol of 90% by weight or less. Preferably, the mixture may contain at least one polyol of 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less. It is also preferable not to use a polyol.

[0057] The mixture of component A and B according to the present invention may contain additives conventionally employed in a polymerizable composition for the purpose of molding an optical article, particularly an ophthalmic lens, namely inhibitors, dyes, photochromic agents, ultraviolet absorbers, fragrances, deodorants, antioxidants, resin modifiers, color balance adjusters, chain extenders, crosslinking agents, free radical scavengers such as antioxidants or hindered amine light stabilizers (HALS), dyes, pigments, fillers, adhesion promoters, anti-yellowing agents, and release agents also in conventional proportions.

[0058] In one embodiment, the additive is added to the first component A before mixing with the second component B.

[0059] Ultraviolet absorbers are often incorporated into optical articles (particularly in ophthalmic lens materials) to reduce or prevent ultraviolet light from reaching the retina. The ultraviolet absorber that can be used in the present invention preferably has the ability to at least partially block light having a wavelength shorter than 400 nm, but may also have an absorption spectrum extending over the visible blue light range (400 - 450 nm), particularly 420 - 450 nm, of the electromagnetic spectrum.

[0060] The ultraviolet absorber protects the user's eyes from ultraviolet light and at the same time protects the base material itself, thereby preventing the base material from weathering and becoming brittle and / or yellowing. The ultraviolet absorber according to the present invention may be, but is not limited to, a benzophenone-based compound, a benzotriazole-based compound, or a dibenzoylmethane-based compound, preferably a benzotriazole-based compound. Suitable ultraviolet absorbers include, but are not limited to, 2-(2-hydroxyphenyl)-benzotriazole, such as 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (Seesorb® 703 / Tinuvin® 326), or other allyl hydroxymethylphenyl chlorobenzotriazoles, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol (Viosorb® 550), n-octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate (Eversorb® 109), 2-(2-hydroxy-5-methoxyphenyl)benzotriazole, 2-(2-hydroxy-5-butoxyphenyl)benzotriazole, and BASF's Tinuvin® CarboProtect®. Preferred absorbers are the benzotriazole family group. Another example of a benzotriazole-based ultraviolet absorber that protects from blue light is described in WO 2017 / 137372 pamphlet.

[0061] The amount of the UV absorber compound according to the present invention used herein is an amount sufficient to obtain sufficient protection from ultraviolet light, but not excessive to prevent precipitation. The ultraviolet absorber compound of the present invention is usually present in an amount in the range of 0.05 to 4% by weight, preferably 0.1 to 3% by weight, more preferably 0.1 to 2% by weight, based on the total weight of the optical material (or per 100 parts by weight of the polymerizable compound present in the mixture of components A and B, or based on the weight of the optical material composition).

[0062] Among the release agents that can be used in the present invention, mention may be made of mono- and dialkyl phosphates, alkyl ester phosphates, silicones, fluorinated hydrocarbons, fatty acids, and ammonium salts. Preferred release agents are mono- and dialkyl phosphates, alkyl ester phosphates, and mixtures thereof. Such release agents are disclosed in particular in US Patent No. 4,975,328 and European Patent No. 271,839. The release agent is preferably used in an amount of 1% by weight or less based on the total weight of the polymerizable compounds present in the mixture of components A and B.

[0063] The polymerizable mixture of the present invention can include a solvent for promoting the dissolution of the catalyst, especially when the catalyst is in the form of a salt.

[0064] Any polar organic solvent such as acetonitrile, tetrahydrofuran, dioxane, ethanol, thioethanol, acetone, and 3-methyl-2-buten-1-ol can be used. The amount of the solvent is usually kept less than 2% by weight, preferably 0 to 0.5% by weight, based on the total weight of the polymerizable compounds present in the mixture of components A and B in order to avoid haze and foaming.

[0065] In the present invention, in the process before the curing step 4), at least one latent catalyst activatable by heat is added, and then the polymerization reaction for forming a polythiourethane-based transparent substrate is promoted by activating the catalyst.

[0066] The catalyst is a system for promoting the polymerization reaction. The catalyst can include one or more latent thermal catalysts. The catalyst used in the method of the present invention is actually a catalyst precursor that becomes an active catalyst when activated.

[0067] The catalyst is used in an effective amount, that is, an amount sufficient to promote the polymerization of the mixture, in the polymerizable composition. Usually, at least one catalyst is used in a proportion of 0.01 to 5% by weight, more preferably 0.02 to 2%, based on the total weight of the polymerizable compounds present in the mixture of components A and B.

[0068] The latent catalyst, or blocked / protected / inducible catalyst, used in this specification is a catalyst that exhibits a delayed action. The latent catalyst does not show significant catalytic activity until it is activated. That is, it does not significantly react with active SH groups, NCO groups, and / or NCX groups. In the present invention, the latent catalyst can be activated by heat and / or radiation depending on its nature.

[0069] The latent catalyst according to the present invention usually exhibits a significantly longer pot life than that of a conventional non-latent catalyst or the pot life of the latent catalyst after activation. For example, the pot life is 1 day or more, preferably 2 days or more.

[0070] The catalyst is usually activated during the curing step 4). If the catalyst is activated during the mixing step 3), the pot life of the mixture will be shortened. There is a possibility that the mixture becomes too viscous too early and cannot be properly filled into the mold.

[0071] The latent catalyst that can be activated by heat is preferably activated by heating at a temperature of at least 40°C, preferably at least 60°C, more preferably at least 80°C, 100°C, or 120°C. This is usually inert at room temperature (20°C), and no significant reaction occurs until the deblocking temperature is reached.

[0072] The latent catalyst can be added at various stages of the method.

[0073] In one embodiment, the catalyst is added to the polythiol monomer and the polyisocyanate monomer or polyisothiocyanate monomer during the preparation of the polythiourethane prepolymer A1 having an isocyanate terminal group or an isothiocyanate terminal group according to the situation, or to the polythiol monomer and the polyisocyanate monomer or polyisothiocyanate monomer during the preparation of the polythiourethane prepolymer B1 having a thiol terminal group, or to the polyisocyanate monomer or polyisothiocyanate monomer during the preparation of component A, or to the polythiol monomer during the preparation of component B.

[0074] In this embodiment, the potentially heat-activatable catalyst has an activation temperature higher than the oligomerization temperature used for the formation of prepolymer A1 or prepolymer B1, depending on the situation. Otherwise, the catalyst may be activated at too early a stage during the preparation of the polythiourethane prepolymer, shortening the pot life of the mixture.

[0075] In this embodiment, when the monomers have sufficient reactivity to form the prepolymer at this temperature, it is preferable to work under conditions where the potentially heat-activatable catalyst according to the invention cannot be activated, for example at a temperature lower than the activation temperature, for example at room temperature.

[0076] In a preferred embodiment, the catalyst is added to the first component A obtained in step 1) before mixing with component B, or to the second component B obtained in step 2) before mixing with component A. In this embodiment, the catalyst is added to prepolymer A1 and / or B1 after preparation, depending on the situation.

[0077] In another preferred embodiment, the catalyst is added to the mixture of components A and B in step 3) of the method.

[0078] In one embodiment, the catalyst is a potentially heat-activatable catalyst selected from protected amines and ammonium salts, and the active form of the catalyst is an amine.

[0079] The protected amine contains one or more covalent bonds that can be cleaved upon heating the latent catalyst to release the amine active form of the catalyst. The amine is preferably protected by at least one isocyanate compound, more preferably two isocyanate compounds.

[0080] The anion of the ammonium salt may be an anion of an acid such as a boron compound or a carboxylic acid. The ionic bond is cleaved by heating, and the amine active form of the catalyst is regenerated.

[0081] The amine produced by heating the latent catalyst is preferably selected from amidines, guanidines, and condensed or bridged bicyclic amines in which at least one bridgehead atom is a nitrogen atom, such as condensed or bridged bicyclic diamines having one or two nitrogen bridgehead atoms, more preferably selected from amidines and guanidines. The amine is more preferably an amine such as 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) compounds, such as 7-alkyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, particularly 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0082] It is well known to those skilled in the art that aromatic heterocyclic compounds containing nitrogen such as imidazole and pyrazole are not amines.

[0083] Preferably, the amine produced by heating the latent catalyst has a pKa in the range of 8 to 14.

[0084] For example, the catalyst may be a latent catalyst obtained from the reaction of an amine with an isocyanate compound such as a polyisocyanate or an acid (such as a carboxylic acid), preferably an amine selected from amidine, guanidine, and a condensed or bridged bicyclic amine in which at least one bridgehead atom is a nitrogen atom, for example, a bridged bicyclic diamine having one or two nitrogen bridgehead atoms. More preferably, the amine is 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), or a 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) compound, such as 7-alkyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, particularly 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Preferably, the latent catalyst is obtained from the reaction of two isocyanates with 1,5-diazabicyclo[4.3.0]non-5-ene (DBN).

[0085] In one embodiment, the catalyst is a latent catalyst obtained from the reaction of two identical or different isocyanates, preferably aryl isocyanates, with 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), or a 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) compound, such as 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Without wishing to be bound by any theory, this isocyanate capping reaction produces a catalyst precursor or blocked catalyst that is an isocyanurate derivative, which reversibly regenerates the active form of the catalyst (DBN, DBU, or 1,5,7-triazabicyclo[4.4.0]dec-5-ene compound) upon heating. Depending on the nature of the aryl group of the aryl isocyanate blocking component, the activation temperature of the latent catalyst is in the range of 40°C to 120°C. This is usually 40, 60, 80, 100, or 120°C or higher.

[0086] In the present application, the term "aryl" represents an aromatic monovalent carbocyclic radical containing only one ring (e.g., phenyl group) or multiple condensed rings (e.g., naphthyl group or terphenyl group), which is optionally substituted with one or more groups such as, but not limited to, alkyl (e.g., methyl), hydroxyalkyl, aminoalkyl, hydroxyl, thiol, amino, halo (fluoro, bromo, iodo, or chloro), nitro, alkylthio, alkoxy (e.g., methoxy), aryloxy, monoalkylamino, dialkylamino, acyl, carboxyl, alkoxycarbonyl, aryloxycarbonyl, hydroxysulfonyl, alkoxysulfonyl, aryloxysulfonyl, alkylsulfonyl, alkylsulfinyl, cyano, trifluoromethyl, tetrazolyl, carbamoyl, alkylcarbamoyl, or dialkylcarbamoyl groups. Alternatively, two adjacent positions of the aromatic ring may be substituted with a methylenedioxy or ethylenedioxy group.

[0087] Formula R 2 -NCO(R 2 =aryl) Non-limiting examples of suitable aryl isocyanates are phenyl isocyanate and 4-fluorophenyl isocyanate.

[0088] In one embodiment, this DBN-based latent catalyst is used in combination with a co-catalyst such as a standard alkyltin catalyst (such as dibutyltin dilaurate), preferably at a molar ratio of latent catalyst / alkyltin catalyst of 40 / 1 or more, more preferably 50 / 1 or more.

[0089] In another embodiment, the catalyst is a latent catalyst obtained from the reaction of an organic carboxylic acid with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), or a 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) compound (e.g., 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene). Without wishing to be bound by any theory, this reaction produces a DBU salt that is inert as a catalyst at room temperature. The organic carboxylic acid functions as a blocker that inhibits the reaction of the DBU salt until the DBU salt is activated by heating and decomposed to regenerate the DBU.

[0090] Depending on the nature of the organic carboxylic acid blocking component, the activation temperature of the latent catalyst is 60, 80, 100, 120, or 130 °C or higher.

[0091] The organic carboxylic acid can be selected from, but is not limited to, acetic acid, cyanoacetic acid, malonic acid, acrylic acid, aryl carboxylic acids such as benzoic acid, preferably benzoic acid. "Aryl" is defined above.

[0092] In another embodiment, the catalyst is a latent catalyst obtained from the reaction of a 7-alkyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (guanidine compound of formula (I)) with two identical or different alkyl isocyanates or arylalkyl isocyanates of the formula R 2 -NCO (R 2 = alkyl or arylalkyl). Without wishing to be bound by any theory, this NCO capping reaction produces a catalyst precursor that is an isocyanurate derivative of formula (II) and is stable in handling, and this becomes the active form of the catalyst upon heating:

Chemical formula

[0093] Depending on the nature of the alkyl isocyanate or arylalkyl isocyanate blocking component, the activation temperature of this thermally latent catalyst is 40, 60, or 80 °C or higher.

[0094] In this patent application, the term "alkyl" means a straight-chain or branched saturated or unsaturated hydrocarbon-based radical containing 1 to 25 carbon atoms, particularly an acyclic radical containing 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, butyl, and n-hexyl groups. The cycloalkyl group preferably contains 3 to 7 carbon atoms, and the cycloalkylmethyl group preferably contains 4 to 8 carbon atoms. The term "alkyl" as used herein also includes alkoxyalkyl groups such as the methoxymethyl group.

[0095] In this patent application, the term "arylalkyl" means an alkyl group substituted with at least one aryl group, such as the trityl group (-CPh3), benzyl group, or 4-methoxybenzyl group. This is bonded to the rest of the molecule via an sp 3 carbon atom.

[0096] Non-limiting examples of suitable alkyl isocyanates or arylalkyl isocyanates are benzyl isocyanate and methyl isocyanate.

[0097] In this method, a plurality of catalysts according to the present invention can be combined. In particular, two or more catalysts with different activation temperatures can be used. In this case, the first catalyst having an activation temperature lower than that of the second catalyst can form a gel while minimizing defects, and then the second catalyst is induced at a higher temperature to complete the polymerization. Such a relay catalyst system can have the advantage of heat formation relayed during the process, so that local heat spots are reduced.

[0098] In the context of the present invention, a gel refers to the reaction product of components A and B with a significantly high conversion rate of reactive functional groups. For example, the conversion rate is in the range of 50 to 80%, preferably about 70%.

[0099] Additional catalysts that are not latent catalysts activatable by heat can also be used in the context of the present invention. Among the additional catalysts that can be used in the method of the present invention, amines such as tertiary amines (e.g., triethylamine or 3,5-lutidine), organometallic compounds (alkyltin or alkyltin oxide, particularly dibutyltin dilaurate, dibutyltin dichloride, and dimethyltin dichloride, etc.), and ammonium salts of acids (these salts satisfy the condition 0.5 < pKa < 14) can be mentioned. In the present application, pKa is preferably represented at 25 °C. pKa can be measured in water at standard pressure by potentiometric (pH) titration using a glass electrode and a pH meter.

[0100] In one embodiment, the method according to the present invention does not use a catalyst that is not a latent catalyst activatable by heat.

[0101] The mixing of the first component A and the second component B can be carried out by any known mixing technique such as that described in US Patent No. 5,973,098. Preferably, components A and B to be mixed are placed in a small reactor chamber and then mixed with a screw mixer. In one embodiment, the viscosity of the mixture of components A and B at 25 °C is in the range of 0.01 Pa·s to 5 Pa·s, preferably 0.05 Pa·s to 0.5 Pa·s, more preferably 0.1 Pa·s to 0.3 Pa·s.

[0102] During step 3), the molding cavity of the casting mold assembly is filled with the mixture of the first component A and the second component B.

[0103] More specifically, the optical material composition can be poured into the cavities of two mold parts integrally held using an annular fastener such as a gasket or tape. Depending on the desired properties of the resulting optical material, degassing can be performed under reduced pressure before pouring the optical material composition into the mold, and / or filtration can be performed under pressure or reduced pressure. After pouring the composition, the cast mold, preferably a lens cast mold, can be heated in an oven or a heating device immersed in water according to a predetermined temperature program to cure the resin in the mold. The resin molded article may be annealed as necessary.

[0104] The curing step of the mixture to obtain the transparent substrate is carried out in the presence of the catalyst according to the present invention and can be implemented using any well-known polymerization technique, particularly thermal polymerization including induction heating and infrared heating, or radiation polymerization. The curing time in step 4) is preferably less than 10 hours or less than 5 hours, more preferably less than 4 hours, less than 3 hours, or less than 2 hours.

[0105] In step 5) of the method, the polythiourethane transparent substrate is recovered from the mold.

[0106] Specific examples of the polythiourethane resin suitable for the present invention are those commercially available from Mitsui Chemicals, Inc. as the MR (registered trademark) series, particularly MR6 (registered trademark), MR7 (registered trademark) (refractive index: 1.67), MR8 (refractive index: 1.6) resin, and MR10 (registered trademark) (refractive index: 1.67). These optical materials and the monomers used in their production are described in particular in U.S. Patent No. 4,689,387, U.S. Patent No. 4,775,733, U.S. Patent No. 5,059,673, U.S. Patent No. 5,087,758, and U.S. Patent No. 5,191,055.

[0107] The following examples illustrate the present invention in a more detailed but non-limiting form. Unless otherwise specified, all thicknesses disclosed in this application relate to physical thickness.

Examples

[0108] Chemicals used The optical material was prepared from a composition containing a polymerizable monomer, a delayed-action catalyst, and Zelec UN (registered trademark) (CAS 3896-11-5) as a release agent. The monomers used in this example to produce a polythiourethane transparent matrix with a refractive index of 1.67 were xylylene diisocyanate (CAS 3634-83-1) and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (CAS 131538-00-6).

[0109] Example 1 Preparation of polythiourethane prepolymer A1 having isocyanate end groups (Component A) A reactor equipped with a condenser, a thermal probe, and a stirrer was charged with a predetermined amount of xylylene diisocyanate (XDI), a polyisocyanate monomer, and heated to 115°C. Then, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol was added and mixed with the polyisocyanate in an amount such that the molar ratio of isocyanate functional groups to thiol functional groups NCO / SH was 8:1. The mixture was heated for 4.5 hours. Thereafter, the obtained prepolymer A1 was cooled to about 35°C, transferred to a suitable drum, and stored in a refrigerator with an inert gas (nitrogen or argon) flowing through it. The viscosity of the final prepolymer having isocyanate end groups at 25°C was about 0.1 Pa·s.

[0110] Prepolymer A1 was prepared without using a catalyst.

[0111] Preparation of polythiourethane prepolymer B1 having thiol end groups (Component B) A reactor equipped with a capacitor, a thermal probe, and a stirrer was charged with a predetermined amount of 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol, a polythiol monomer, and heated to 90 °C. Then, xylylene diisocyanate was added and mixed with the polythiol in an amount such that the molar ratio of thiol functional groups to isocyanate functional groups SH / NCO was 8:1. The mixture was heated for 3 hours. The end of the reaction was indicated by the temperature reaching a peak and returning to 90 °C (±2 °C). Thereafter, the obtained prepolymer B1 was cooled to about 35 °C, transferred to a suitable drum, and stored in a refrigerator while flowing an inert gas (nitrogen or argon). The viscosity of the final prepolymer having thiol end groups at 25 °C was about 0.5 Pa·s.

[0112] Prepolymer B1 was prepared without using a catalyst.

[0113] Preparation of latent catalyst C1 [Chemical formula] 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (1 equivalent), a guanidine compound, was dissolved in tetrahydrofuran (THF). Then, the mixture was cooled to 0 °C. Benzyl isocyanate (2 equivalents) was added dropwise, and the mixture was stirred under nitrogen for 24 hours. Thereafter, the solvent was distilled off at room temperature, and the solid residue was further dried under vacuum for 24 hours to obtain the expected latent catalyst as a colorless solid.

[0114] Preparation of polythiourethane transparent casting substrate A convex and a concave mold were assembled using tape. The central thickness was 2 mm.

[0115] Prepolymers A1 and B1 were prepared as described above. 299.68 g of the cooled prepolymer A1 was mixed with 0.175 g of latent catalyst C1 and 0.0480 g of Zelec UN (registered trademark). This mixture was stirred at 15 °C and degassed for 1 hour to form Component A. 281.57 g of prepolymer B1 was stirred at 15 °C and degassed for 1 hour to form Component B. Then, Components A and B were mixed in a small reactor while stirring and degassing at room temperature for 5 minutes. The viscosity of the resulting mixture at 25 °C was about 0.1 - 0.3 Pa·s. After completion of mixing, a clean syringe was used to fill the mold. The assembled mold was held at room temperature for 10 minutes and then placed in a convection oven heated to 120 °C for 3 hours to carry out the polymerization reaction. Then, the mold was disassembled to obtain a plano (without degree) lens with a central thickness of 2 mm. This lens included the body of a polythiourethane-based transparent thermosetting substrate having a refractive index of 1.67 and had no optical defects such as streak-like scratches. This lens was immersed in a surfactant solution and sonicated for cleaning, and then rinsed and dried.

[0116] Example 2 It is the same as Example 1 except that latent catalyst C2 was used instead of latent catalyst C1.

[0117] Preparation of Latent Catalyst C2 [Chemical formula] A solution of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN, 1 equivalent) in dry THF was added dropwise to a cold solution (-10 °C) of 4-fluorophenyl isocyanate (2 equivalents) in dry toluene. The mixture was stirred under nitrogen for 24 hours. Next, the solvent was evaporated to dryness at room temperature, and then the solid residue was further dried under vacuum for 24 hours to obtain the expected latent catalyst as a colorless solid.

[0118] Example 3 It is the same as Example 1 except that latent catalyst C3 was used instead of latent catalyst C1 and heating was carried out at 130 °C in the molding step.

[0119] Preparation of Latent Catalyst C3 [Chemical formula] Latent catalyst C3 was prepared by neutralizing 1 equivalent of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with 1 equivalent of benzoic acid in THF under a nitrogen atmosphere. The salt immediately precipitated as a white solid. This was filtered, washed with cold THF, and then dried under vacuum for 24 hours.

Claims

1. A method for rapidly curing a polythiourethane-based transparent casting substrate, comprising the following steps 1), 2), 3), 4), and 5): 1) Preparing a first component A containing a polythiourethane prepolymer A1 having an isocyanate terminal group or isothiocyanate terminal group of the formula -NCX (X is O or S) from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer; 2) Preparing a second component B containing a polythiourethane prepolymer B1 having a thiol terminal group from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer; Or 1) Preparing a first component A containing at least one polyisocyanate monomer or polyisothiocyanate monomer; 2) Preparing a second component B containing a polythiourethane prepolymer B1 having a thiol terminal group from a polythiol monomer and a polyisocyanate monomer or polyisothiocyanate monomer; Or 1) Preparing a first component A containing a polythiourethane prepolymer A1 having an isocyanate terminal group or isothiocyanate terminal group of the formula -NCX (X is O or S) from a polythiol monomer and a polyisocyanate monomer or polyisothiocyanate monomer; 2) Preparing a second component B containing at least one polythiol monomer; 3) Mixing the first and second components A and B together and filling the resulting mixture into the molding cavity of a casting mold assembly; 4) Curing the mixture to obtain a polythiourethane-based transparent substrate, and 5) Recovering the polythiourethane-based transparent substrate from the casting mold assembly Including At least one heat-activatable latent catalyst is added in the process before the curing step 4), and then the catalyst is activated to promote the polymerization reaction for forming the polythiourethane-based transparent substrate.

2. The method according to claim 1, wherein the latent catalyst is added to the polythiol monomer and the polyisocyanate monomer or polyisothiocyanate monomer during the preparation of the polythiourethane prepolymer A1 having an isocyanate terminal group or an isothiocyanate terminal group, or is added to the polythiol monomer and the polyisocyanate monomer or polyisothiocyanate monomer during the preparation of the polythiourethane prepolymer B1 having a thiol terminal group.

3. The method according to claim 1, wherein the latent catalyst is added to the first component A obtained in step 1) before mixing with component B, or is added to the second component B obtained in step 2) before mixing with component A.

4. The method according to claim 1, wherein the latent catalyst is added to the mixture of components A and B in step 3).

5. The method according to any one of claims 1 to 4, wherein the latent catalyst is activated during the curing step 4).

6. The method according to any one of claims 1 to 5, wherein the latent catalyst activatable by heat is activated by heating at a temperature of at least 40 °C, preferably at least 60 °C.

7. The method according to any one of claims 1 to 6, wherein the latent catalyst is obtained from the reaction of an amine with an isocyanate or an acid.

8. The method according to any one of claims 1 to 7, wherein the latent catalyst is obtained from the reaction of two isocyanates with 1,5-diazabicyclo[4.3.0]non-5-ene.

9. The method according to any one of claims 1 to 8, wherein the latent catalyst is obtained from the reaction of an organic carboxylic acid with 1,8-diazabicyclo[5.4.0]undec-7-ene.

10. The method according to any one of claims 1 to 9, wherein the latent catalyst is obtained from the reaction of 7-alkyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene with two alkyl isocyanates or two arylalkyl isocyanates.

11. The method according to any one of claims 1 to 10, wherein the curing time in step 4) is less than 10 hours, preferably less than 5 hours.

12. The amount of the polyisocyanate monomer or polyisothiocyanate monomer and the polythiol monomer is adjusted such that, for the preparation of the polythiourethane prepolymer A1, the molar ratio of NCX / SH groups in the mixture of the polyisocyanate monomer or polyisothiocyanate monomer and the polythiol monomer is in the range of 3:1 to 30:1, and / or for the preparation of the polythiourethane prepolymer B1, the molar ratio of SH / NCX groups in the mixture of the polyisocyanate monomer or polyisothiocyanate monomer and the polythiol monomer is in the range of 3:1 to 30:1, where X in the formula is O or S, the method according to any one of claims 1 to 11.

13. The method according to any one of claims 1 to 12, wherein the substrate is an optical lens substrate.

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