Method for rapid curing of polythionocarbamate-based substrates using delayed action catalysts

Abstract

The present invention relates to a method of rapidly curing a transparent cast substrate based on polythionocarbamate, the method comprising, in a preferred embodiment, providing a first component A comprising a polythionocarbamate prepolymer A1 having isocyanate or isothiocyanate end groups, providing a second component B comprising a polythionocarbamate prepolymer B1 having thiol end groups, the first component A and the second component B are mixed together and the mold cavity of the casting mold assembly is filled with the resulting mixture, said mixture is cured to obtain the transparent substrate, at least one heat-activatable latent catalyst being added in the method prior to curing step 4), and subsequently activating the catalyst to accelerate the polymerization reaction forming the polythionocarbamate-based transparent substrate.

Description

[0001] The present invention relates to a method for making polythiourethane-based substrates, and in particular optical substrates such as ophthalmic lenses, which typically have a medium or high refractive index of 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 in a short cure cycle.

[0002] Background and Summary of the Invention

[0003] Ophthalmic lenses made from polythiourethane-based substrates are typically made by a process that includes mixing appropriate monomers (such as a mixture of polyisocyanates and polythiols) in a tank, adding catalysts and additives, filling a mold cavity with the liquid mixture of monomers, polymerizing the monomer mixture, and thereafter recovering the polymerized polythiourethane-based substrate from the mold. The mixture is typically subjected to a thermal cycle in an oven for a typical duration of 20 hours.

[0004] The fast curing method is highly desirable compared to conventional methods, since shorter residence times in the curing oven allow for a significant increase in productivity, complex and demanding lens geometries can be obtained at higher yields due to lower shrinkage of the final polymerizable mixture than that obtained directly from the monomers, better compatibility with tape adhesives used for mold assembly, and reduced energy consumption during the polymerization cycle.

[0005] It is known to reduce the time required to cure a polymerizable composition injected into a mold assembly by using oligomers rather than monomers. The monomers are first pre-reacted to form oligomers, then blended with a catalyst (which provides high overall reactivity in a very small volume) or even blended by in-line mixing equipment, and then injected into the mold assembly which is subjected to a short polymerization cycle (typically a few hours).

[0006] In this regard, US2003 / 125410 discloses a method for rapidly curing a polythiourethane transparent casting substrate, the method comprising the following steps:

[0007] 1) providing a first component A comprising a polythiourethane prepolymer having isocyanate or isothiocyanate terminal groups,

[0008] 2) providing a second component B comprising a polythiourethane prepolymer having thiol end groups,

[0009] 3) mixing the first component A and the second component B together and filling the mold cavity of the casting mold assembly with the resulting mixture,

[0010] 4) Curing the mixture in the presence of a highly reactive catalyst to obtain a transparent solid substrate to significantly shorten the curing time of the polymerizable composition to within a typical 2 hours.

[0011] If the viscosity is controlled, the batch mixing of such mixtures is inherently safer than the conventional method of mixing from monomers, because a portion of the available bonding energy has been released during the oligomer formation (prepolymerization), which limits the formation of local hot spots in the final polymerizable mixture. The use of prepolymers allows a stable and steady reaction. The known catalysts used for the synthesis of polythiourethanes are mixtures of dibutyltin dichloride or KSCN and 18-crown ether-6. However, when all the ingredients are mixed together, they will react and form a gel in less than 10 minutes at room temperature.

[0012] In applications EP 3916470 and EP 3919967, a different approach is chosen for the rapid curing of polythiourethane optical materials, using a combination of monomers and prepolymers in the presence of a polymerization catalyst, typically a basic catalyst.

[0013] However, the main technical problem of the fast curing methods described in the prior art is the short pot life of the polymerizable mixture, which places a great restriction on the mixing / filling step, since highly intimate mixing of very viscous prepolymers is only allowed for a short time before gelling. Therefore, a polymerizable mixture with a longer pot life, for example, a polymerizable mixture with a longer time range before reaching a viscosity that is no longer processable (mixing / filling) would be a great advantage to extend the mixing time, especially important because the mixture is highly viscous. In addition, similar to the customary methods starting from monomers, such a mixture can be advantageously processed in batches.

[0014] It is therefore an object of the present invention to provide a process for rapidly curing transparent cast substrates based on polythiourethanes which remedies the disadvantages of the prior art processes with regard to the shortened pot life of the polymerizable mixtures.

[0015] Another object of the present invention is to provide a method for rapidly curing transparent polythiourethane-based cast substrates which are substantially free of optical defects, in particular bubbles and / or streaks resulting from the polymerization process.

[0016] The present inventors have discovered that the reactivity of the polymerizable mixture can be minimized by using specific catalysts that are blended in an inactive form and exhibit essentially no catalytic effect in the polymerizable mixture but are subsequently triggered to form the final polythiourethane-based polymer. These catalysts allow for better control of the polymerization reaction.

[0017] The present invention provides a method for rapidly curing a transparent polythiourethane-based cast substrate useful for making optical articles such as ophthalmic lenses, the method comprising the following steps:

[0018] 1) providing a first component A from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the first component comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate terminal groups of the formula -NCX, wherein X is O or S,

[0019] 2) providing a second component B from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the second component comprising a polythiourethane prepolymer B1 having thiol end groups,

[0020] or:

[0021] 1) providing a first component A comprising at least one polyisocyanate or polyisothiocyanate monomer,

[0022] 2) providing a second component B from polythiol and polyisocyanate or polyisothiocyanate monomers, the second component comprising a polythiourethane prepolymer B1 having thiol terminal groups,

[0023] or:

[0024] 1) providing a first component A from polythiol and polyisocyanate or polyisothiocyanate monomers, wherein the first component comprises a polythiourethane prepolymer A1 having isocyanate or isothiocyanate terminal groups of the formula -NCX, wherein X is O or S,

[0025] 2) providing a second component B comprising at least one polythiol monomer,

[0026] 3) mixing the first component A and the second component B together and filling the mold cavity of the casting mold assembly with the resulting mixture,

[0027] 4) curing the mixture to obtain a polythiourethane-based transparent substrate, and

[0028] 5) recovering the polythiourethane-based transparent substrate from the mold assembly,

[0029] In this process, at least one thermally activatable latent catalyst is used before the curing step 4), and the catalyst is subsequently activated.

[0030] In the present invention, at least one heat-activatable latent catalyst is added in the process before the curing step 4), and the catalyst is subsequently activated to accelerate the polymerization reaction to form the polythiourethane-based transparent substrate.

[0031] The method of the present invention provides several advantages in addition to those mentioned above.

[0032] The reactivity of the final formulated polymerizable mixture is essentially the same as that of the uncatalyzed blend, and it can be made to flow through pipes to a filling station with less risk of blockage due to localized gelation.

[0033] All components (including the catalyst) can be mixed together over a period of time that is compatible with very high levels of mixing, thereby reducing the possibility of inhomogeneities and optical defects such as streaks. DETAILED DESCRIPTION

[0034] The substrate of the present invention is an organic glass substrate made of a thermosetting resin. The polymer matrix of the substrate is obtained from a material composition ("substrate composition") comprising at least one, preferably at least two polymerizable prepolymers.

[0035] The substrate is preferably an optical article substrate, more preferably an optical lens substrate. The optical article is preferably an ophthalmic lens, such as a plastic spectacle lens.

[0036] In this specification, unless otherwise specified, a substrate is understood to be transparent when no significant contrast loss is perceived when viewing an image through the substrate, i.e., when an image formed through the substrate is obtained without adversely affecting the quality of the image. Unless otherwise specified, this definition of the term "transparent" can be applied to all objects so defined in this specification.

[0037] The term "ophthalmic lens" is used to mean a lens that fits into a spectacle frame to protect the eyes and / or correct vision. The lens may be selected from afocal, monofocal, bifocal, trifocal, progressive and Fresnel lenses or any other type of lens with a discontinuous surface. Although ophthalmic optics is a preferred field of the present invention, it is understood that the present invention may be applied to other types of optical elements, such as lenses for optical instruments, filters (particularly filters for photography or astronomy), optical sight lenses, eye goggles, optics for lighting systems, screens, inlaid glass, etc.

[0038] If the optical article is an optical lens, it may be coated with one or more functional coatings on its front main surface, rear main side or both sides. As used herein, the back of the substrate is intended to mean the face closest to the wearer's eyes when the article is used. The back is usually a concave face. Conversely, the front of the substrate is the face farthest from the wearer's eyes when the article is used. The front is usually a convex face. The optical article may also be a flat light article.

[0039] In the sense of the present invention, a substrate is understood to mean an uncoated substrate and generally has two main faces. The substrate may in particular be an optically transparent material having the shape of an optical article, such as an ophthalmic lens destined to be mounted in spectacles. In this context, the term "substrate" is understood to mean the basic constituent material of an optical lens and more particularly an ophthalmic lens. This material may serve as a support for a stack of one or more coatings or layers.

[0040] The refractive index of the polythiourethane-based transparent substrate is preferably 1.52 or more, more preferably 1.54 or more, more preferably 1.56 or more, more preferably 1.58 or more, more preferably 1.60 or more, and still more preferably 1.65 or more, and it is preferably 1.80 or less, more preferably 1.70 or less, and still more preferably 1.67 or less. Unless otherwise specified, the refractive index mentioned in the present application is expressed at 25° C., 550 nm wavelength.

[0041] The fast curing polymerizable compositions that produce polythiourethane-based materials are composed of two main components.

[0042] In the first embodiment of the present invention, the first component A is composed of a polythiourethane prepolymer A1 having isocyanate (NCO) or isothiocyanate (NCS) terminal groups, and the second component B is composed of a polythiourethane prepolymer B1 having thiol (SH) terminal groups.

[0043] In step 1) of the first and third embodiments of the process of the invention, a first component A is provided which comprises a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups and has been prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the latter being used in excess. The first component A thus comprises oligomers and unpolymerized initial monomers.

[0044] In step 2) of the first and second embodiments of the process of the invention, a second component B is provided which comprises a polythiourethane prepolymer B1 having thiol end groups and has been prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the former being used in excess. The second component B thus comprises oligomers and unpolymerized initial monomers.

[0045] In a second embodiment of the present invention, the first component A is composed of at least one polyisocyanate or polyisothiocyanate monomer, and the second component B is composed of a polythiourethane prepolymer B1 having thiol (SH) end groups.

[0046] In a third embodiment of the present invention, the first component A is composed of a polythiourethane prepolymer A1 having isocyanate (NCO) or isothiocyanate (NCS) terminal groups, and the second component B is composed of at least one polythiol monomer.

[0047] In contrast to prior art processes using only iso(thio)cyanate or thiol monomers, the present invention uses at least one prepolymer.

[0048] Prepolymer means a polymer or oligomer comprising a prepolymer molecule. A prepolymer molecule means a macromolecule or oligomer molecule that is capable of entering into further polymerization through a reactive (polymerizable) group, thereby contributing more than one monomer unit to at least one chain of the final macromolecule. Prepolymer molecules are usually formed from two or more different monomers.

[0049] The polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups is prepared by reacting at least one polyisocyanate or polyisothiocyanate monomer with at least one polythiol monomer, preferably in the absence of a catalyst, in a ratio such that the molar ratio of isocyanate or isothiocyanate groups to thiol groups NCX / SH is preferably in the range of 3:1 to 30:1, X being O or S.

[0050] The polythiourethane prepolymer B1 having thiol end groups is prepared by reacting at least one polyisocyanate or polyisothiocyanate monomer with at least one polythiol monomer, preferably in the absence of a catalyst, in a ratio such that the molar ratio of thiol groups to isocyanate or isothiocyanate groups SH / NCX is preferably in the range of 3:1 to 30:1, X being O or S.

[0051] The polythiol and polyisocyanate or polyisothiocyanate compounds used to prepare the polythiourethane prepolymers A1 or B1 are considered monomers herein even when they are oligomers.

[0052] Polyisocyanate means any compound containing at least two isocyanate groups, in other words, diisocyanate, triisocyanate, etc. Polyisocyanate prepolymers can be used. The polyisocyanate can be any suitable polyisocyanate having two or more, preferably two or three isocyanate functional groups.

[0053] The polyisocyanate may be selected from aliphatic, aromatic, cycloaliphatic or heterocyclic polyisocyanates and mixtures thereof.

[0054] Polyisothiocyanates are defined in the same manner as the above-mentioned polyisocyanates by replacing the "isocyanate" group with an "isothiocyanate" group.

[0055] Preferred polyisocyanates or isothiocyanate monomers are those having the formula:

[0056]

[0057] Where R 1 are independently H or C1-C5 alkyl, preferably CH3 or C2H5;

[0058] R 2is H, halogen, preferably Cl or Br, or C1-C5 alkyl, preferably CH3 or C2H5;

[0059] Z is -N=C=X, wherein X is O or S, preferably O;

[0060] a is an integer ranging from 1 to 4, b is an integer ranging from 2 to 4, and a+b≤6; and

[0061] x is an integer of 1-10, preferably 1-6.

[0062] The polyisocyanate of the present invention is preferably a diisocyanate. Among the diisocyanates available for use, there can be mentioned toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, p-phenylene 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, perhydrophenylmethane-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.

[0063] 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 use in the present invention are described in detail in WO 98 / 37115, WO 2014 / 133111 or EP 1877839.

[0064] The polythiol that can be used in the present invention is defined as a compound containing at least two sulfhydryl (mercapto) groups, in other words, dithiol, trithiol, tetrathiol, etc. Polythiol prepolymers can be used. The polythiol can be any suitable polythiol having two or more, preferably two or three thiol functional groups.

[0065] Among the preferred polythiol monomers and / or oligomers suitable according to the invention, there may be mentioned aliphatic polythiols such as 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(mercapto 1-(2-mercaptoethyl)thio)-1-propanethiol, 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 and 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'-mercaptobutylthio)-2,3-dimercaptopropane, 1-(5'-mercaptopentylthio)-2,3-dimercaptopropane, 1-(6'-mercaptohexylthio)-2,3-dimercaptopropane, 1,2-bis-(4'-mercaptobutylthio)-3-mercaptopropane, 1,2-bis-(5'-mercaptopentylthio)-3-mercaptopropane, 1,2-bis-(6'-mercaptohexylthio)-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'-mercaptobutylthio)propane, 1,2,3-tris-(6'-mercaptohexylthio)propane, methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanethiol-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, EP 394495, US 4775733 or EP 1877839:

[0066]

[0067] Preferred embodiments are a combination of xylylene diisocyanate and pentaerythritol tetrakis(3-mercaptopropionate); a combination of xylylene diisocyanate and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol; a 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-propanethiol; a combination of xylylene diisocyanate and 4 ,8 (or 4,7 or 5,7)-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane; a combination of dicyclohexylmethane diisocyanate and 4,8 (or 4,7 or 5,7)-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane; or a 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-propanethiol, as shown below:

[0068]

[0069] Preferably, the polythiol has a value of 1 Pa.s or less, more preferably 5.10 -1 Pa.s or less, more preferably 2.5.10 -1 Pa.s or less, more preferably 2.10 -1 Pa.s or less, more preferably 10 -1 Pa.s or less, and even more preferably 0.5.10 -1 Viscosity at 25°C of Pa.s or less.

[0070] Depending on the embodiment of the invention, components A and B are prepared by polymerizing a mixture of at least one polyisocyanate and / or at least one polyisothiocyanate monomer and at least one polythiol monomer and optionally a polyol monomer or a polyamine monomer in the desired amount. Typically, components A and B can be prepared by classical thermal polymerization including induction and infrared heating.

[0071] The amounts of polyisocyanate or polyisothiocyanate monomers and polythiol monomers in the reaction medium are preferably adjusted in each case in such a way that the molar ratio of NCX / SH groups of the mixture of polyisocyanate or polyisothiocyanate monomers and polythiol monomers for the preparation of the polythiourethane prepolymer A1 is in the range from 3:1 to 30:1, preferably from 6:1 to 10:1, and / or the molar ratio of SH / NCX groups of the mixture of polyisocyanate or polyisothiocyanate monomers and polythiol monomers for the preparation of the polythiourethane prepolymer B1 is in the range from 3:1 to 30:1, preferably from 6:1 to 10:1, X being O or S.

[0072] In one embodiment, both components A and B are prepared without the use of a catalyst system, which allows better control of the polymerization reaction and produces a prepolymer with high stability over time. However, they can be prepared using a catalyst or catalyst system as described above.

[0073] Typically, in the first embodiment of the present invention, the prepolymer A1 and the prepolymer B1 are contained in the mixture in such an amount that the molar ratio of NCX to SH groups is from 0.8 to 1.2, preferably 1.

[0074] Typically, in the second embodiment of the present invention, the at least one polyisocyanate or polyisothiocyanate monomer and the prepolymer B1 are contained in the mixture in such an amount that the molar ratio of NCX to SH groups is from 0.8 to 1.2, preferably 1.

[0075] Typically, in the third embodiment of the present invention, the prepolymer A1 and the at least one polythiol monomer are contained in the mixture in such an amount that the molar ratio of NCX to SH groups is from 0.8 to 1.2, preferably 1.

[0076] Typically, in the second embodiment of the invention, the polyisocyanate or polyisothiocyanate of component A and the prepolymer B1 are contained in the mixture in such an amount that the molar ratio of NCX to SH groups is from 0.8 to 1.2, preferably 1.

[0077] Typically, in the third embodiment of the invention, the prepolymer A1 and the polythiol of component B are contained in the mixture in such an amount that the molar ratio of NCX to SH groups is from 0.8 to 1.2, preferably 1.

[0078] The preparation of prepolymers B1 having thiol end groups has been described in US Pat. No. 5,908,876. A similar process can be used to prepare component B of the invention.

[0079] When component A of the invention comprises a polythiourethane prepolymer A1, it can be prepared in an analogous manner, but with the desired ratio of polyisocyanate or polyisothiocyanate to polythiol monomers in order to obtain a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups.

[0080] The mixture polythiol / polyiso(thio)cyanate from which the prepolymer A1 is obtained may contain 90% by weight or less of at least one polyol. Preferably, the mixture may contain 80% by weight or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less of at least one polyol. Also preferably, no polyol is used. Polyiso(thio)cyanate means polyisocyanate or polyisothiocyanate.

[0081] The mixture polythiol / polyiso(thio)cyanate from which the prepolymer B1 is obtained may contain 90% by weight or less of at least one polyol. Preferably, the mixture may contain 80% by weight or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less of at least one polyol. Also preferably, no polyol is used.

[0082] The mixture of components A and B according to the invention may also contain additives conventionally used in polymerizable compositions intended for molding optical articles, in particular ophthalmic lenses, in conventional proportions, namely inhibitors, dyes, photochromics, UV absorbers, fragrances, deodorants, antioxidants, resin modifiers, color balancers, chain extenders, crosslinkers, free radical scavengers such as antioxidants or hindered amine light stabilizers (HALS), dyes, pigments, fillers, adhesion promoters, anti-yellowing agents and release agents.

[0083] In one embodiment, the additive is added to the first component A prior to mixing with the second component B.

[0084] UV absorbers are often incorporated into optical articles in order to reduce or prevent UV light from reaching the retina (particularly in ophthalmic lens materials). UV absorbers that can be used in the present invention preferably have the ability to at least partially block light having a wavelength shorter than 400 nm, but may also have an absorption spectrum extending to the visible blue range of the electromagnetic spectrum (400-450 nm), particularly 420-450 nm.

[0085] The UV absorber protects the user's eyes from UV light and protects the substrate material itself, thereby preventing it from weathering and becoming brittle and / or yellowing. The UV absorber according to the present invention can be, but is not limited to, a benzophenone-based compound, a benzotriazole-based compound, or a dibenzoylmethane-based compound, preferably a benzotriazole compound. Suitable UV absorbers include, but are not limited to, 2-(2-hydroxyphenyl)-benzotriazole such as 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole ( 703 / 326), or other allyl hydroxymethylphenyl chlorobenzotriazole, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol ( 550), n-octyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate ( 109), 2-(2-hydroxy-5-methoxyphenyl)benzotriazole, 2-(2-hydroxy-5-butoxyphenyl)benzotriazole and BASF Preferred absorbers are from the benzotriazole family. Further examples of benzotriazole UV absorbers that protect against blue light can be found in WO 2017 / 137372.

[0086] The amount of the UV absorber compound according to the present invention used herein is an amount sufficient to provide satisfactory protection from UV light, but not excessive to prevent precipitation. The UV absorber compound of the present invention is generally present in an amount ranging from 0.05% to 4% by weight, preferably from 0.1% to 3% by weight, more preferably from 0.1% to 2% by weight, relative to 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 relative to the weight of the optical material composition).

[0087] Among the release agents that can be used in the present invention, there can be mentioned mono- and dialkyl phosphates, alkyl phosphates, silicones, fluorinated hydrocarbons, fatty acids and ammonium salts. Preferred release agents are mono- and dialkyl phosphates, alkyl phosphates and mixtures thereof. Such release agents are disclosed in particular in US 4975 328 and EP 271 839. The release agent is preferably used in an amount less than or equal to 1% by weight, based on the total weight of the polymerizable compounds present in the mixture of components A and B.

[0088] The polymerizable mixture of the present invention may contain a solvent for facilitating dissolution of the catalyst, especially if the catalyst is in the form of a salt.

[0089] Any polar organic solvent may be used, such as acetonitrile, tetrahydrofuran, dioxane, ethanol, thioethanol, acetone and 3-methyl-2-butene-1-ol. The amount of solvent is generally kept below 2% by weight, and preferably 0 to 0.5% by weight, based on the total weight of polymerizable compounds present in the mixture of components A and B, to avoid turbidity and bubbling.

[0090] In the present invention, at least one heat-activatable latent catalyst is added in the process before the curing step 4), and the catalyst is subsequently activated to accelerate the polymerization reaction to form the polythiourethane-based transparent substrate.

[0091] The catalyst is a system used to accelerate the polymerization reaction. The catalyst may comprise one or more latent thermal catalysts. The catalyst used in the process of the invention is in fact a precatalyst which produces an active catalyst after activation.

[0092] The catalyst should be used in an effective amount (i.e., an amount sufficient to promote polymerization of the mixture) in the polymerizable composition. Typically, the at least one catalyst is used in a proportion of 0.01% to 5%, more preferably 0.02% to 2% by weight relative to the total weight of polymerizable compounds present in the mixture of components A and B.

[0093] As used herein, a latent catalyst or blocking / protection / triggerable catalyst is a catalyst that exhibits a delayed action. A latent catalyst will not exhibit a significant catalytic action, i.e., will not react significantly with active SH, NCO and / or NCX groups prior to activation. In the present invention, a latent catalyst may be activated by heat and / or radiation, depending on its properties.

[0094] The latent catalyst according to the present invention generally exhibits a pot life significantly longer than the pot life of conventional non-latent catalysts or the pot life of the latent catalyst once activated. For example, the pot life is 1 day or longer, and preferably 2 days or longer.

[0095] 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. The mixture will quickly become too viscous and may not fill the mold properly.

[0096] The heat-activatable latent catalyst 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. It is generally inactive at room temperature (20° C.) and does not react appreciably until its deblocking temperature is reached.

[0097] The latent catalyst may be added at different stages of the process of the present invention.

[0098] In one embodiment, the catalyst is added to the polythiol and the polyisocyanate or polyisothiocyanate monomer during the preparation of the polythiourethane prepolymer A1 having an isocyanate or isothiocyanate terminal group, or the catalyst is added to the polythiol and the polyisocyanate or polyisothiocyanate monomer during the preparation of the polythiourethane prepolymer B1 having a thiol terminal group, or the catalyst is added to the polyisocyanate or polyisothiocyanate monomer during the preparation of component A, or the catalyst is added to the polythiol monomer during the preparation of component B.

[0099] In this embodiment, the activation temperature of the heat-activatable latent catalyst should be higher than the oligomerization temperature used to form prepolymer A1 or prepolymer B1, as the case may be. Otherwise, the catalyst may be activated at a too early stage during the preparation of the polythiourethane prepolymer and the pot life of the mixture will be shortened.

[0100] In this embodiment, if the monomers are sufficiently reactive at the activation temperature to form prepolymers, it is preferred to work under conditions which do not allow activation of the heat-activatable latent catalyst according to the invention (such as at temperatures lower than this temperature, for example at room temperature).

[0101] In a preferred embodiment, the catalyst is added to the first component A obtained in step 1) before mixing with component B, or the catalyst is added to the second component B obtained in step 2) before mixing with component A. In this embodiment, the catalyst is added to the prepolymer A1 and / or B1 after the preparation of the prepolymer A1 and / or B1, as the case may be.

[0102] In another preferred embodiment, the catalyst is added to the mixture of components A and B in step 3) of the process of the invention.

[0103] In one embodiment, the catalyst is a latent catalyst selected from protected amines and ammonium salts, wherein the active form of the catalyst is an amine.

[0104] The protected amine contains one or more covalent bonds which can be broken upon heating of the latent catalyst, thereby releasing the amine active form of the catalyst.The amine is preferably protected with at least one isocyanate compound, more preferably two isocyanate compounds.

[0105] 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 may be broken upon heating to regenerate the amine active form of the catalyst.

[0106] The amine generated by heating the latent catalyst is preferably selected from amidines, guanidines, and fused or bridged bicyclic amines in which at least one of the bridgehead atoms is a nitrogen atom (such as fused 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, in particular 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0107] It is well known to those skilled in the art that aromatic heterocyclic compounds containing nitrogen, such as imidazole or pyrazole, are not amines.

[0108] Preferably, the amine produced by heating the latent catalyst has a pKa in the range of 8-14.

[0109] For example, the catalyst can be a latent catalyst obtained by the reaction of an amine and an isocyanate compound (such as a polyisocyanate) or an acid (such as a carboxylic acid), preferably the amine is selected from amidines, guanidines and fused or bridged bicyclic amines in which at least one of the bridgehead atoms is a nitrogen atom, such as bridged bicyclic diamines 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 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, in particular 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).

[0110] In one embodiment, the catalyst is a latent catalyst obtained by the reaction of two identical or different isocyanates, preferably an aryl isocyanate, with 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) compounds (such as 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene). Without wishing to be bound by any theory, the isocyanate blocking reaction produces an isocyanurate derivative precatalyst or blocked catalyst, 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 aromatic group of the aryl isocyanate blocking component, the activation temperature of the latent catalyst ranges from 40°C to 120°C. The temperature is typically greater than or equal to 40°C, 60°C, 80°C, 100°C, or 120°C.

[0111] In the present application, the term "aryl" refers to an aromatic monovalent carbocyclic group containing only one ring (e.g., phenyl) or several condensed rings (e.g., naphthyl or terphenyl), which may be optionally substituted with one or more groups, such as, but not limited to, alkyl (e.g., methyl), hydroxyalkyl, aminoalkyl, hydroxy, thiol, amino, halogen (fluorine, bromine, iodine or chlorine), 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. Alternatively, two adjacent positions of the aromatic ring may be substituted with methylenedioxy or ethylenedioxy.

[0112] With formula R 2 -NCO (where R 2 Non-limiting examples of suitable aryl isocyanates (eg, 4-(4-(4-phenyl)-1-yl)) are phenyl isocyanate and 4-fluorophenyl isocyanate.

[0113] In one embodiment, the DBN-based latent catalyst is used in combination with a cocatalyst such as a standard alkyltin catalyst (eg, dibutyltin dilaurate) in a molar ratio of latent catalyst / alkyltin catalyst preferably greater than or equal to 40 / 1, more preferably greater than or equal to 50 / 1.

[0114] In another embodiment, the catalyst is a latent catalyst obtained by 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 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) compounds such as 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Without wishing to be bound by any theory, the reaction produces a DBU salt that is catalytically inactive at room temperature. The organic carboxylic acid acts as a blocking agent to prevent the DBU salt from reacting until it is activated by heating, which decomposes the salt to regenerate the DBU.

[0115] Depending on the nature of the organic carboxylic acid blocking component, the activation temperature of the latent catalyst is higher than or equal to 60°C, 80°C, 100°C, 120°C or 130°C.

[0116] The organic carboxylic acid may be selected from, but not limited to, acetic acid, cyanoacetic acid, malonic acid, acrylic acid, aryl carboxylic acids such as benzoic acid, preferably benzoic acid. "Aryl" is as defined above.

[0117] In another embodiment, the catalyst is a 7-alkyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (a guanidine compound of formula (I)) and two identical or different compounds of formula R 2 -NCO (where R 2 Without wishing to be bound by any theory, the NCO-capping reaction produces a bench-stable isocyanurate derivative precatalyst having formula (II) which, upon heating, produces the active form of the catalyst:

[0118]

[0119] Depending on the nature of the alkyl isocyanate or aryl alkyl isocyanate blocking component, the activation temperature of such thermolatent catalysts is greater than or equal to 40° C., 60° C. or 80° C.

[0120] In the present patent application, the term "alkyl" means a linear or branched, saturated or unsaturated hydrocarbon-based group containing 1 to 25 carbon atoms, especially including acyclic groups containing 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, butyl and n-hexyl, preferably a cycloalkyl containing 3 to 7 carbon atoms, preferably a cycloalkylmethyl containing 4 to 8 carbon atoms. The term "alkyl" as used herein also includes alkoxyalkyl, such as methoxymethyl.

[0121] In the present patent application, the term "arylalkyl" means an alkyl group substituted by at least one aryl group, such as trityl (-CPh3), benzyl or 4-methoxybenzyl. 3 The carbon atom is attached to the rest of the molecule.

[0122] Non-limiting examples of suitable alkyl isocyanates or arylalkyl isocyanates are benzyl isocyanate and methyl isocyanate.

[0123] Several catalysts according to the invention can be combined in the method of the invention. In particular, two or more catalysts with different activation temperatures can be used. In this case, a first catalyst having an activation temperature lower than that of a second catalyst can form a gel while minimizing defects, and then trigger a second catalyst at a higher temperature to drive the polymerization to completion. Such relay catalytic systems can have the advantage of relaying heat formation during the method, thereby reducing local hot spots.

[0124] In the context of the present invention, gel means the reaction product of components A and B, wherein the conversion of the reactive functional groups is very high. For example, the conversion ranges from 50% to 80%, and is preferably about 70%.

[0125] In the context of the present invention, additional catalysts that are not thermally activatable latent catalysts can also be used. Among the additional catalysts that can be used in the process of the present invention, amines such as tertiary amines (e.g., triethylamine or 3,5-dimethylpyridine), organometallic compounds such as alkyl tin or alkyl tin oxide (especially dibutyltin dilaurate, dibutyltin dichloride, and dimethyltin dichloride), and ammonium salts of acids that satisfy the condition 0.5 < pKa < 14 can be cited. In the present application, pKa is preferably expressed at 25 °C. pKa can be measured in water by potentiometric (pH) titration using a glass electrode and a pH meter under standard pressure.

[0126] In one embodiment, the process according to the present invention does not use a catalyst that is not a thermally activatable latent catalyst.

[0127] The mixing of the first component A and the second component B can be carried out by any known mixing technique (such as those mentioned in US 5,973,098). Preferably, the components A and B to be mixed are added to 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 ranges from 0.01 Pa·s to 5 Pa·s, preferably from 0.05 Pa·s to 0.5 Pa·s, and even more preferably from 0.1 Pa·s to 0.3 Pa·s.

[0128] During step 3), the cavity of the mold assembly is filled with the mixture of the first component A and the second component B.

[0129] More specifically, the optical material composition can be injected into the cavity of two mold parts held together using an annular closure (such as a gasket) or tape. Depending on the desired characteristics of the resulting optical material, degassing can be carried out under reduced pressure and / or filtration can be carried out under increased or reduced pressure before injecting the optical material composition into the mold. After pouring the composition, the mold, preferably a lens mold, can be heated in an oven or heating device immersed in water according to a predetermined temperature program to cure the resin in the mold. If necessary, the resin molded product can be annealed.

[0130] The curing step of the mixture providing 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, and especially thermal polymerization (including induction and infrared heating) or radiation polymerization. The curing time of step 4) is preferably less than 10 or 5 hours, more preferably less than 4, 3, or 2 hours.

[0131] In step 5) of the process of the present invention, the polysulfide polyurethane transparent substrate is recovered from the mold.

[0132] Specific examples of polythiourethane resins suitable for use in the present invention are those produced by Mitsui Chemicals Company under the trade name Those sold in series, especially (Refractive index: 1.67), (Refractive index: 1.6) resin, (Refractive index: 1.67). These optical materials and the monomers used for their preparation are described in particular in patents US Pat. Nos. 4,689,387, 4,775,733, 5,059,673, 5,087,758 and 5,191,055.

[0133] The following examples illustrate the invention in a more detailed but non-limiting manner. Unless otherwise stated, all thicknesses disclosed in this application relate to physical thicknesses.

[0134] Examples

[0135] Chemicals used

[0136] The optical material comprises a polymerizable monomer, a delayed action catalyst and a Zelec The monomers used in the examples of the present invention are xylylene diisocyanate (CAS 3634-83-1) and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (CAS 131538-00-6) to produce a polythiourethane transparent matrix with a refractive index of 1.67.

[0137] Example 1

[0138] Preparation of polythiourethane prepolymer A1 (component A) having isocyanate terminal groups

[0139] In a reactor equipped with a condenser, a thermal probe and an agitator, a determined amount of the polyisocyanate monomer xylylene diisocyanate (XDI) is charged and heated to 115°C. Then, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol is introduced and mixed with the polyisocyanate in an amount such that the molar ratio of isocyanate functional groups to thiol functional groups NCO / SH is 8:1. The mixture is heated for 4.5 hours. The resulting prepolymer A1 is then cooled to about 35°C and transferred to a suitable drum, purged (tap) with an inert gas (nitrogen or argon) and stored in a cold room. The final prepolymer with isocyanate end groups has a viscosity at 25°C of about 0.1 Pa.s.

[0140] Prepolymer A1 was prepared without using a catalyst.

[0141] Preparation of polythiourethane prepolymer B1 (component B) having thiol terminal groups

[0142] In a reactor equipped with a condenser, a thermal probe and a stirrer, a determined amount of the polythiol monomer 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol is charged and heated to 90°C. Then, xylylene diisocyanate is introduced and mixed with the polythiol in such an amount that the molar ratio of thiol functional groups to isocyanate functional groups SH / NCO is 8:1. The mixture is heated for 3 hours. The end of the reaction is indicated by reaching a peak and returning to a temperature of 90°C (+ / -2°C). The resulting prepolymer B1 is then cooled to about 35°C and transferred to a suitable drum, purged with an inert gas (nitrogen or argon) and stored in a cold room. The final prepolymer with thiol end groups has a viscosity at 25°C of about 0.5 Pa.s.

[0143] Prepolymer B1 was prepared without using a catalyst.

[0144] Preparation of latent catalyst C1

[0145]

[0146] The guanidine compound 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (1 equivalent) was dissolved in tetrahydrofuran (THF). The mixture was then cooled to 0°C. Benzyl isocyanate (2 equivalents) was added dropwise, and the mixture was stirred under nitrogen for 24 hours. The solvent was then stripped at room temperature, and the solid residue was further vacuum dried for 24 hours to obtain the expected latent catalyst as a colorless solid.

[0147] Preparation of Transparent Polythiourethane Casting Substrate

[0148] Assemble the male and female molds by using adhesive tape. The center thickness is 2mm.

[0149] Prepolymers A1 and B1 were prepared as described above. 299.68 g of cooled prepolymer A1 was mixed with 0.175 g of latent catalyst C1 and 0.0480 g of Zelec Mix. The mixture was stirred and degassed at 15°C for 1 hour to form component A. 281.57g of prepolymer B1 was stirred and degassed at 15°C for 1 hour to form component B. Components A and B were then mixed in a small reactor while stirring and degassed at room temperature for 5 minutes. The resulting mixture had a viscosity at 25°C of about 0.1 to 0.3 Pa.s. Once the mixing was complete, the mold was filled with the aid of a clean syringe. The assembled molds were kept at room temperature for 10 minutes, after which they were inserted into a convection oven heated at 120°C for 3h to perform the polymerization reaction. The mold was then disassembled to obtain a plano (no-power) lens with a center thickness of 2mm, the plano lens comprising a body of a polythiourethane transparent thermosetting substrate having a refractive index of 1.67 and no optical defects such as streaks. The lenses were cleaned by immersion and ultrasound in a surfactant solution, then rinsed and dried.

[0150] Example 2

[0151] Similar to Example 1, except that latent catalyst C2 was used instead of latent catalyst C1.

[0152] Preparation of latent catalyst C2

[0153]

[0154] A solution of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN, 1 eq) in dry THF was added dropwise to a cold solution (-10°C) of 4-fluorophenylisocyanate (2 eq) in dry toluene. The mixture was stirred under nitrogen for 24 hours. The solvent was then stripped to dryness at room temperature, and the solid residue was further dried under vacuum for 24 hours to give the expected latent catalyst as a colorless solid.

[0155] Example 3

[0156] Similar to Example 1, except that latent catalyst C3 was used instead of latent catalyst C1 and heating at 130° C. was performed during the molding step.

[0157] Preparation of Latent Catalyst C3

[0158]

[0159] 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 nitrogen atmosphere. The salt precipitated quickly as a white solid, which was filtered and washed with cold THF, then dried under vacuum for 24 hours.

Claims

1. A method for rapidly curing a transparent casting substrate based on polythiourethane, the method comprising the following steps 1), 2), 3), 4) and 5): 1) providing a first component A from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the first component comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate terminal groups of the formula -NCX, wherein X is O or S, 2) providing a second component B from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the second component comprising a polythiourethane prepolymer B1 having thiol end groups, or: 1) providing a first component A comprising at least one polyisocyanate or polyisothiocyanate monomer, 2) providing a second component B from polythiol and polyisocyanate or polyisothiocyanate monomers, the second component comprising a polythiourethane prepolymer B1 having thiol terminal groups, or: 1) providing a first component A from polythiol and polyisocyanate or polyisothiocyanate monomers, wherein the first component comprises a polythiourethane prepolymer A1 having isocyanate or isothiocyanate terminal groups of the formula -NCX, wherein X is O or S, 2) providing a second component B comprising at least one polythiol monomer, 3) mixing the first component A and the second component B together and filling the mold cavity of the casting mold assembly with the resulting mixture, 4) curing the mixture to obtain a polythiourethane-based transparent substrate, and 5) recovering the polythiourethane-based transparent substrate from the mold assembly, In the method, at least one heat-activatable latent catalyst is added before the curing step 4), and the catalyst is subsequently activated to accelerate the polymerization reaction to form the polythiourethane-based transparent substrate.

2. The method of claim 1, wherein: The latent catalyst is added to the polythiol and polyisocyanate or polyisothiocyanate monomers during the preparation of the polythiourethane prepolymer A1 having isocyanate or isothiocyanate terminal groups, or the latent catalyst is added to the polythiol and polyisocyanate or polyisothiocyanate monomers during the preparation of the polythiourethane prepolymer B1 having thiol terminal groups.

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

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

5. A method as claimed in any one of the preceding claims, wherein: The latent catalyst is activated during the curing step 4).

6. A method as claimed in any one of the preceding claims, wherein: The heat-activatable latent catalyst is activated by heating at a temperature of at least 40°C, preferably at least 60°C.

7. A method as claimed in any one of the preceding claims, wherein: The latent catalysts are obtained from the reaction of amines with isocyanates or acids.

8. A method as claimed in any one of the preceding claims, wherein The latent catalyst is obtained from the reaction of two isocyanates with 1,5-diazabicyclo[4.3.0]non-5-ene.

9. A method as claimed in any one of the preceding claims, wherein: The latent catalyst is obtained by the reaction of an organic carboxylic acid with 1,8-diazabicyclo[5.4.0]undec-7-ene.

10. A method as claimed in any one of the preceding claims, wherein: The latent catalyst is obtained by the reaction of 7-alkyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene with two alkyl isocyanates or two aryl alkyl isocyanates.

11. A method as claimed in any one of the preceding claims, wherein: The curing time of step 4) is less than 10 hours, preferably less than 5 hours.

12. A method as claimed in any one of the preceding claims, wherein: The amounts of the polyisocyanate or polyisothiocyanate monomers and the polythiol monomers are adjusted so that the molar ratio of the NCX / SH groups of the mixture of the polyisocyanate or polyisothiocyanate monomers and the polythiol monomers used to prepare the polythiourethane prepolymer A1 is in the range of 3:1 to 30:1, and / or the molar ratio of the SH / NCX groups of the mixture of the polyisocyanate or polyisothiocyanate monomers and the polythiol monomers used to prepare the polythiourethane prepolymer B1 is in the range of 3:1 to 30:1, and X is O or S.

13. A method as claimed in any one of the preceding claims, wherein: The substrate is an optical lens substrate.

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