Method for curing polythiourethane-based substrates bonded to microstructured wafers

Abstract

The present invention relates to a method for curing a polythiourethane-based casting substrate, comprising: providing a first component A comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups of formula -NCX, where X is O or S; providing a second component B comprising a polythiourethane prepolymer B1 having thiol end groups or at least one polythiol monomer B2; providing a microstructured wafer made of a thermoplastic material, the wafer having an inner surface and an outer surface, the inner surface having the microstructure; mixing the first and second components A and B together; and filling the resulting mixture into a mold cavity, the mold cavity being defined by the inner surface of the microstructured wafer and at least a portion of a mold part; curing the mixture; and obtaining a polythiourethane-based substrate adhered to the microstructured wafer.

Description

[Technical Field]

[0001] The present invention relates to a method for producing microstructured wafer-bonded polythiourethane-based substrates, particularly optical substrates such as ophthalmic lenses, generally having a 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, using a short cure cycle. [Background technology]

[0002] Ophthalmic lenses made from polythiourethane-based substrates are typically prepared by a process that involves mixing appropriate monomers, such as a mixture of polyisocyanate and polythiol, in a tank, adding a catalyst and additives, filling a mold cavity with the liquid mixture of monomers, polymerizing the monomer mixture, and then recovering the polymerized polythiourethane-based substrate from the mold. The mixture is usually subjected to a thermal cycle in an oven, typically for 20 hours.

[0003] WO 00 / 26272 discloses a polymerizable composition for producing a poly(thio)urethane resin, comprising at least one polyiso(thio)cyanate monomer, at least one polythiol monomer, and a salt catalyst system (typically a mixture of KSCN and a crown ether).

[0004] U.S. Patent Application Publication No. 2007 / 098999 discloses a method for obtaining a polythiourethane light-polarizing article, comprising: placing a polarizing polyvinyl alcohol film in a molding cavity of a two-part mold assembly; pouring into the molding cavity a polymerizable composition comprising at least one poly(iso)thiocyanate monomer and at least one polythiol, or a mixture of at least one liquid NCO- or NCS-terminated poly(thio)urethane prepolymer and at least one liquid SH-terminated poly(thio)urethane prepolymer; curing the polymerizable composition; and removing the polythiourethane light-polarizing article from the molding cavity.

[0005] EP 3640714 A1 discloses a method for encapsulating microstructures such as microlenses, including forming a first optical element having an optical surface defining a plurality of recesses or protrusions, placing the first optical element in a two-part mold assembly, introducing a moldable material into the mold cavity, and forming a second optical element such that the second optical element bonds with the first optical element to encapsulate the microstructures. Similar processes are also described in EP 3640713 A1 and EP 3910411 A1. However, these processes cannot be used to form wafers starting from monomers into integral parts of polythiourethane lenses due to incompatibility issues.

[0006] In fact, it has been found that casting polythiourethane lenses using functionalized wafers with microstructures is difficult: When standard polythiourethane monomers, such as polyisocyanates mixed with polythiols, are used, diffusion of the monomers from the surface of the wafer into the interior of the wafer occurs, causing swelling of the wafer (typically a polycarbonate wafer), which can cause the final lens to become opaque and / or alter the microstructure geometry.

[0007] Therefore, there is a need for a technical solution that allows compatibility between the wafer and the mixture of polymerizable compounds that form the polythiourethane matrix, and respects the shape of the microstructures.

[0008] U.S. Patent Application Publication No. 2003 / 125410 discloses a method for curing a polythiourethane transparent casting substrate, the method comprising: 1) providing a first component A comprising a polythiourethane prepolymer having isocyanate or isothiocyanate end groups; 2) providing 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 the casting mold assembly; 4) curing the mixture to obtain a transparent solid substrate; Includes:

[0009] In the applications EP 3916470 and EP 3919967, a different approach to curing polythiourethane optical materials was chosen, combining the use of monomers and prepolymers in the presence of a polymerization catalyst (typically a basic catalyst). However, these methods have not been applied to the production of microstructured articles. Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to provide a method for obtaining a thermosetting polythiourethane-based cast substrate bonded to a wafer having a microstructure, which alleviates the drawbacks of prior art methods observed at the interface between the wafer and the polymer substrate. The method of casting a microstructured heat-cured lens must preserve the design integrity of the microstructure.

[0011] Another object of the present invention is to provide a method for curing polyurethane-based cast substrates that have high transmittance and clarity and a low yellowness index while being substantially free of optical defects caused by the polymerization process.

[0012] The inventors have found that the use of polythiourethane prepolymers having isocyanate or isothiocyanate end groups rather than isocyanate or isothiocyanate monomers can improve compatibility and prevent wafer swelling and microstructural shape alterations that result in haze at the polymer interface. [Means for solving the problem]

[0013] The present invention relates to a method for curing a polythiourethane-based casting substrate that can be used to manufacture optical articles such as ophthalmic lenses, comprising the following steps 1), 2), 3), 4), 5), 6), or 1'), 2'), 3), 4), 5), 6): 1) providing a first component A comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups of formula -NCX, where X is O or S, said prepolymer A1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; 2) providing a second component B comprising a polythiourethane prepolymer B1 having thiol end groups, said prepolymer B1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; or 1') providing a first component A comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups of formula -NCX, where X is O or S, said prepolymer A1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; 2') providing a second component B comprising at least one polythiol monomer B2; 3) providing a microstructured thermoplastic wafer, the wafer having an inner surface and an outer surface, the inner surface having the microstructure; 4) mixing the first and second components A and B together and filling the resulting mixture into a mold cavity, the mold cavity being defined by the inner surface of the microstructured wafer and at least a portion of the mold part; 5) curing the mixture to obtain a polythiourethane-based substrate; and 6) recovering the polythiourethane substrate adhered to the microstructured wafer; The present invention provides a method comprising:

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

[0015] In the method of the present invention, some monomers are first pre-reacted to form oligomers, which are then poured into a mold assembly that undergoes a short polymerization cycle, typically several hours. By at least partially replacing the monomers with prepolymers (or oligomers), the time required to cure the polymerizable composition poured into the mold assembly is dramatically reduced.

[0016] The rapid curing process is highly desirable because it dramatically increases productivity due to shorter residence times in the curing oven, allows for better yields of complex and demanding lens shapes due to lower shrinkage of the final polymerizable mixture than mixtures obtained directly from the monomer, provides excellent compatibility with tape adhesives used in mold assembly, and reduces energy consumption during the polymerization cycle.

[0017] Batch mixing of such mixtures is inherently safer than conventional processes using monomers because, if the viscosity is controlled, some of the available bond-forming energy is already released during oligomerization (prepolymerization), limiting the formation of localized hot spots in the final polymerizable mixture. The use of prepolymers allows for a stable and uniform reaction.

[0018] The foregoing and other objects, features, and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a stage of the method, namely step 4). [Figure 2] FIG. 1 is a schematic diagram of a stage of the method, namely step 6). [Figure 3] 1 shows the haze values ​​of three different optical articles produced in the experimental part. [Figure 4] 1 shows the transmittance (Tv) values ​​of three different optical articles fabricated in the experimental part. DETAILED DESCRIPTION OF THE INVENTION

[0020] The substrate of the present invention is an organic glass substrate made from a thermosetting resin. The polymer matrix of the substrate is obtained, in some embodiments, from a material composition ("substrate composition") comprising at least one polymerizable prepolymer and at least two polymerizable prepolymers.

[0021] The substrate is preferably an optical article substrate, more preferably an optical lens substrate. The optical article is preferably an ophthalmic lens, for example a plastic eyeglass lens.

[0022] In this specification, unless otherwise specified, a substrate is understood to be transparent if the observation of an image through said substrate is perceived without significant loss of contrast. That is, a substrate is understood to be transparent if the formation of an image through said substrate is obtained without adversely affecting the quality of this image. This definition of the term "transparent" can be applied to all objects so modified in this specification, unless otherwise specified.

[0023] The term "ophthalmic lens" is used to mean a lens that is fitted to a spectacle frame to protect the eyes and / or correct vision. Said lens may be chosen from afocal, monofocal, bifocal, trifocal, progressive, Fresnel, or any other type of lens with discontinuous surfaces. Although ophthalmic optical systems are the preferred field of the invention, it will be understood that the invention may be applied to other types of optical elements, such as, for example, lenses for optical instruments, in particular filters for photography or astronomy, optical aiming lenses, eye visors, the optics of lighting systems, screens, glass panes, etc.

[0024] When the optical article is an optical lens, it may have one or more functional coatings on the front main surface, the rear main surface, or both surfaces. As used herein, the rear surface of the substrate is intended to mean the surface that is closest to the wearer's eyes when the article is in use. This is usually a concave surface. In contrast, the front surface of the substrate is the surface that is farthest from the wearer's eyes when the article is in use. This is usually a convex surface. The optical article may also be a plano article.

[0025] Substrate, in the sense of the present invention, should be understood as meaning an uncoated substrate and generally has two main surfaces. The substrate may in particular be an optically transparent material having the shape of an optical article (for example, an ophthalmic lens to be attached to glass). In this context, the term "substrate" is understood as meaning the base component material of an optical lens (more particularly, an ophthalmic lens). This material may serve as a support for one or more coatings or layer stacks.

[0026] The refractive index of the polythiourethane-based 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, even more preferably 1.65 or more, and is preferably 1.80 or less, more preferably 1.70 or less, even more preferably 1.67 or less. Unless otherwise specified, refractive indices referred to in this application are expressed at 25°C at a wavelength of 550 nm.

[0027] The fast-setting polymerizable composition for obtaining polythiourethane-based materials is composed of two main components.

[0028] In a first embodiment of the present invention, which is a preferred embodiment, the first component A is composed of a polythiourethane prepolymer A1 having isocyanate (NCO) or isothiocyanate (NCS) end groups; the second component B is composed of a polythiourethane prepolymer B1 having thiol (SH) end groups.

[0029] In step 1) of the first embodiment of the method (and step 1' of the second embodiment of the method), a first component A is provided, comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups, which is prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer, the latter being used in excess. Thus, first component A comprises oligomers and unpolymerized initial monomers.

[0030] In step 2) of the first embodiment of the method, a second component B is prepared, comprising a polythiourethane prepolymer B1 having thiol end groups, prepared from at least one polythiol monomer and at least one polyisocyanate monomer or polyisothiocyanate monomer, the former being used in excess. Thus, the second component B comprises oligomers and unpolymerized initial monomers.

[0031] In a second embodiment of the present invention, the first component A is composed of a polythiourethane prepolymer A1 having isocyanate (NCO) or isothiocyanate (NCS) end groups, and the second component B is composed of at least one polythiol monomer B2.

[0032] In comparison to prior art processes that use only iso(thio)cyanate or thiol monomers, the present invention uses at least one prepolymer, particularly at least one polythiourethane prepolymer having isocyanate or isothiocyanate end groups.

[0033] Prepolymer refers to a polymer or oligomer that includes a prepolymer molecule. A prepolymer molecule refers to a polymer or oligomer molecule that can enter into further polymerization via reactive (polymerizable) groups, thereby contributing multiple monomer units to at least one chain of the final polymer. Prepolymer molecules are generally formed from two or more different monomers.

[0034] The polythiourethane prepolymer A1 having an isocyanate or isothiocyanate end group is prepared by reacting at least one polyisocyanate monomer or polyisothiocyanate monomer with at least one polythiol monomer in a ratio such that the molar ratio of the isocyanate or isothiocyanate group to the thiol group, NCX / SH (X is O or S), is preferably in the range of 3:1 to 30:1, preferably without a catalyst.

[0035] The polythiourethane prepolymer B1 having thiol terminal groups is prepared by reacting at least one polyisocyanate monomer or polyisothiocyanate monomer with at least one polythiol monomer in a molar ratio of thiol groups to isocyanate groups or isothiocyanate groups SH / NCX (X is O or S) preferably in the range of 3:1 to 30:1, preferably without a catalyst.

[0036] The polythiol compounds and polyisocyanate or polyisothiocyanate compounds used to prepare the polythiourethane prepolymers A1 or B1 are considered monomers herein, even if they are oligomers.

[0037] By polyisocyanate is meant any compound containing at least two isocyanate groups, i.e., diisocyanates, triisocyanates, etc. Polyisocyanate prepolymers may also be used. The polyisocyanate may be any suitable polyisocyanate having two or more, preferably two or three, isocyanate functional groups.

[0038] The polyisocyanate may be selected from aliphatic, aromatic, cycloaliphatic, or heterocyclic polyisocyanates, and mixtures thereof.

[0039] Polyisothiocyanates are defined similarly to the polyisocyanates above, with the "isocyanate" group replaced by an "isothiocyanate" group.

[0040] Preferred polyisocyanate or isothiocyanate monomers are those of the formula: [ka] wherein R 1 are independently H or a C1-C5 alkyl group, preferably CH3 or C2H5; R 2 is H, halogen, preferably Cl or Br, or a C1-C5 alkyl group, preferably CH3 or C2H5; Z is -N=C=X, where X is O or S, preferably O; a is an integer ranging from 1 to 4, b is an integer ranging from 2 to 4, and a+b≦6; x is an integer of 1 to 10, preferably an integer of 1 to 6.

[0041] The polyisocyanates of the present invention are preferably diisocyanates. Among the available diisocyanates are 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 Examples of the isocyanate include 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.

[0042] Another non-limiting example of a polyisocyanate is the isocyanurate 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 1 877 839.

[0043] The polythiol that can be used in the present invention is defined as a compound containing at least two sulfhydryl (mercapto) groups, i.e., a dithiol, trithiol, tetrathiol, etc. Polythiol prepolymers can also be used. The polythiol can be any suitable polythiol having two or more, preferably two or three, thiol functional groups. This polythiol can be used not only for the preparation of polythiourethane prepolymer A1 or B1, but also directly in component B in step 2') of the present method.

[0044] Among the preferred polythiol monomers and / or oligomers suitable for the present invention are 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)dis ... sulfide, 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, 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'-mercapentylthio)-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,Aliphatic polythiols such as 2-propanedithiol, 1,6-hexanethiol-1,2,3-propanetrithiol, and 1,2-bis(2'-mercaptoethylthio)-3-mercaptopropane can be mentioned. Further examples of polythiols are shown in the following formula or can be found in WO 2014 / 133111, EP 394495, U.S. Pat. No. 4,775,733, or EP 1,877,839: [ka] and C2H5C(CH2COOCH2CH2SH)3

[0045] Preferred embodiments include 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, a combination of pentaerythritol tetrakis(3-mercaptopropionate) and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol; a combination of xylylene diisocyanate and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol; A combination of an isocyanate 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 shown below: [ka]

[0046] Preferably, the polythiol has a viscosity of 1 Pa.s or less at 25°C, more preferably 5.10 Pa.s or less. -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 more preferably 0.5.10 -1 Pa.s or less.

[0047] Specific examples of polythiourethane resins suitable for the present invention are those commercially available from Mitsui Chemicals, Inc. under the MR® series, in particular MR6®, MR7® (refractive index: 1.67), MR8 (refractive index: 1.6) resin, and MR10® (refractive index: 1.67). These optical materials and the monomers used in their preparation are described, inter alia, in U.S. Pat. Nos. 4,689,387, 4,775,733, 5,059,673, 5,087,758, and 5,191,055.

[0048] Depending on the embodiment of the present invention, components A and B are prepared by polymerizing a mixture of the required amounts of at least one polyisocyanate and / or at least one polyisothiocyanate monomer, at least one polythiol monomer, and optional polyol or polyamine monomers. Typically, components A and B can be prepared by conventional thermal polymerization, including infrared heating.

[0049] The amounts of polyisocyanate monomers or polyisothiocyanate monomers and polythiol monomers in the reaction medium are preferably adjusted in each case so that, for the preparation of polythiourethane prepolymer A1, the molar ratio of NCX / SH groups of the polyisocyanate monomers or mixtures of polyisothiocyanate monomers and polythiol monomers is in the range of 3:1 to 30:1, preferably in the range of 6:1 to 10:1, and / or, for the preparation of polythiourethane prepolymer B1, the molar ratio of SH / NCX groups of the polyisocyanate monomers or mixtures of polyisothiocyanate monomers and polythiol monomers is in the range of 3:1 to 30:1, preferably in the range of 6:1 to 10:1, where X is O or S.

[0050] In one embodiment, both components A and B are prepared without a catalyst system, which allows for better control of the polymerization reaction and results in prepolymers that are stable over time, however, they can also be prepared using catalysts as described below.

[0051] Typically, in the first embodiment of the present invention, prepolymer A1 and prepolymer B1 are contained in the mixture in amounts such that the molar ratio of NCX groups to SH groups is 0.8 to 1.2, preferably 1.

[0052] Typically, in the second embodiment of the present invention, the prepolymer A1 and the at least one polythiol monomer of component B are contained in the mixture in amounts such that the molar ratio of NCX groups to SH groups is between 0.8 and 1.2, preferably 1.

[0053] The preparation of prepolymer B1 having thiol end groups has already been described in US Patent No. 5,908,876. A similar process can be used to prepare component B of the present invention.

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

[0055] The polythiol / polyiso(thio)cyanate mixture used to obtain prepolymer A1 may contain up to 90% by weight of at least one polyol. Preferably, the mixture may contain up to 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% by weight of at least one polyol. Also preferably, no polyol is used. By polyiso(thio)cyanate is meant polyisocyanate or polyisothiocyanate.

[0056] The polythiol / polyiso(thio)cyanate mixture for obtaining prepolymer B1 may contain up to 90% by weight of at least one polyol. Preferably, the mixture may contain up to 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% by weight of at least one polyol. Also preferably, no polyol is used.

[0057] The mixture of components A and B according to the present invention may also contain additives in conventional proportions conventionally employed in polymerizable compositions intended for the molding of optical articles, in particular ophthalmic lenses, namely inhibitors, dyes, photochromic agents, UV absorbers, fragrances, deodorants, antioxidants, resin modifiers, color balancing agents, chain extenders, crosslinkers, free radical scavengers such as antioxidants or hindered amine light stabilizers (HALS), dyes, pigments, fillers, adhesion promoters, anti-yellowing agents, and mold release agents.

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

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

[0060] The UV absorber not only protects the user's eyes from UV light but also protects the substrate material itself, thereby preventing the substrate from becoming brittle and / or yellowing due to weathering. The UV 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, and preferably a benzotriazole-based compound. Suitable UV absorbers include, but are not limited to, 2-(2-hydroxyphenyl)-benzotriazoles such as 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (Seesorb® 703 / Tinuvin® 326) or other arylhydroxymethylphenylchlorobenzotriazoles, 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. Further examples of benzotriazole UV absorbers that protect against blue light can be found in WO 2017 / 137372.

[0061] The amount of UV absorber compound according to the present invention used herein is sufficient to provide adequate protection from UV light, but not excessive to prevent precipitation. The UV absorber compound according to the present invention is generally present in an amount ranging from 0.05 to 4 wt. %, preferably from 0.1 to 3 wt. %, more preferably from 0.1 to 2 wt. %, 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 di-alkyl phosphates, alkyl ester phosphates, silicones, fluorinated hydrocarbons, fatty acids, and ammonium salts. Preferred release agents are mono- and di-alkyl phosphates, alkyl ester phosphates, and mixtures thereof. Such release agents are particularly disclosed in U.S. Pat. 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 may contain a solvent to facilitate dissolution of the catalyst, especially when the catalyst is in the form of a salt.

[0064] Any polar organic solvent can be used, such as acetonitrile, tetrahydrofuran, dioxane, ethanol, thioethanol, acetone, and 3-methyl-2-buten-1-ol. The amount of solvent is generally kept below 2 wt. % based on the total weight of the polymerizable compounds present in the mixture of components A and B, preferably 0-0.5 wt. % to avoid haze and foaming. In one embodiment, the catalyst is used in the form of a solution of a compound such as 2-mercaptoethanol.

[0065] In the present invention, at least one catalyst may be used in the process before the curing step 5). In one embodiment, the mixture obtained in step 4) comprises at least one catalyst.

[0066] The catalyst is a system for promoting the polymerization reaction. The catalyst can contain one or more latent thermal catalysts.

[0067] The catalyst is used in the polymerizable composition in an effective amount, that is, an amount sufficient to promote the polymerization of the mixture. Usually, at least one catalyst is used at a ratio 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 catalyst can be added at various stages of the process.

[0069] In one embodiment, the catalyst is added to the polythiol monomer B2 during the preparation of component B or to the polythiol-terminated polythiourethane prepolymer B1, depending on the situation.

[0070] In one embodiment, the catalyst is added to the first component A obtained in step 1) or 1') before being mixed with component B, or to the second component B obtained in step 2) or 2') before being mixed with component A. In this embodiment, the catalyst can be added to the prepolymer A1 and / or B1 after the preparation of the prepolymer A1 and / or B1, depending on the situation.

[0071] In another preferred embodiment, the catalyst is added to the mixture of components A and B in step 4) of the process.

[0072] In one embodiment, the catalyst is an anionic catalyst. Preferred catalysts are transition metal-based catalysts and ammonium salts of acids, and these salts preferably satisfy the condition of 0.5 < pKa ≤ 14.

[0073] In one embodiment, the catalyst is of the formula

Number

[0074] The preferred metal cation of the salt is Li + , Na + , K. + , Rb + , Mg 2+ , Ca 2+ , Ba 2+ and Al 3+ A particularly preferred metal cation is Li because it is colorless and soluble in the composition. + , Na + , and K + Transition metals are less preferred because their salts can result in colored compositions and, therefore, colored polymerized resins. In one embodiment, the method of the present invention does not use a tin-containing catalyst.

[0075] Preferred NR + In the four groups, R is a C1 to C8 alkyl group, more preferably a methyl group, an ethyl group, a propyl group, a butyl group, or a hexyl group.

[0076] Preferably, Y - is an anion such that the corresponding acid YH satisfies the condition 0.5≦pKa≦10, more preferably 0.5≦pKa≦8.

[0077] Preferably, the anion Y - is an anion of thiocyanate, carboxylate, thiocarboxylate, acetylacetonate, diketone anion, acetoacetate anion, malonate anion, cyanoacetate anion, ketonitrile anion, and an anion of formula RS -(wherein R is preferably a substituted or unsubstituted alkyl group having 2 to 10 carbon atoms, or an aryl group having preferably 6 to 12 carbon atoms).

[0078] Preferred anion Y - is the SCN - , acetylacetonate, acetate, thioacetate, formate, and benzoate. A preferred salt catalyst is KSCN.

[0079] Among the catalysts that can be used in the process of the invention, mention may also be made of amines, such as tertiary amines (e.g. triethylamine or 3,5-lutidine), organometallic compounds, such as alkyltins or alkyltin oxides, in particular dibutyltin dilaurate, dibutyltin dichloride, and dimethyltin dichloride. Several catalysts according to the invention can be combined in the process.

[0080] In particular, when the reactivity of the thiol and / or iso(thio)cyanate contained in the polymerizable composition is insufficient, an electron donor compound can also be used in combination with the catalyst, preferably a salt catalyst. Generally, the electron donor compound stabilizes the cation of the catalyst salt. Therefore, the electron donor compound contributes to dissociating the anion / cation ion pair, thereby increasing the anion reactivity in the polymerization medium and thus accelerating the polymerization reaction.

[0081] The electron donor compound is preferably selected from acetonitrile compounds, such as malononitrile, amides, amines, imines, phosphines, sulfones, sulfoxides, trialkyl phosphites, triaryl phosphites, ethylene glycol ethers, crown ethers, and cryptands. Preferred electron donor compounds are crown ethers, cryptands, trialkyl phosphites, triaryl phosphites, and malononitrile.

[0082] Examples of acetonitrile compounds are: [ka] In the formula, R is an alkyl group, preferably a C1 to C6 alkyl group, for example, methyl, ethyl, propyl, or butyl.

[0083] The amide compounds may be primary, secondary, or tertiary amide compounds. Trialkyl phosphites and triaryl phosphites have the formula: [ka] where R, R', and R''' are either alkyl groups (preferably C1-C6 alkyl groups) or aryl groups (e.g., phenyl groups) preferably having 6 to 12 carbon atoms. Preferred is a trialkyl phosphite, for example (C2H5O)3P.

[0084] The electron donor compound may also be selected from crown ethers and cryptands.

[0085] These cyclic molecules are usually selected to provide a good compromise between the size of the heteroatom or metal and the size of the "cage", i.e., between the number and size of the heteroatoms and the size of the "cage", i.e., between the number of heteroatoms and the size of the ring.

[0086] Preferred crown ethers and cryptands are of the formula: [ka] where X 1 represents O, S, or NH, x1 is an integer of 3 to 6, preferably an integer of 3 to 4, and n1 is 2 or 3; X 2 , X 3 , and X4 represent O or S; n2, n3, n4, y2, y3, and y4 are 2 or 3; and x2, x3, and x4 are 2 or 3.

[0087] Among the preferred crown ethers and cryptands are the following compounds: [ka] Examples include:

[0088] Examples of preferred crown ethers are 18-crown-6, 18-crown-7, 15-crown-5, and 15-crown-6.

[0089] The electron donor compound is preferably present in an amount ranging from 0 to 5% by weight, preferably from 0 to 1% by weight, based on the total weight of the polymerizable compounds present in the mixture of components A and B.

[0090] In step 3) of the method, a microstructured wafer made of a thermoplastic material is provided, having an inner (major) surface and an outer (major) surface, the inner surface of the wafer having the microstructure.

[0091] In another embodiment, the wafer has both major surfaces with the same or different microstructures, i.e., the outer surface of the wafer also has a microstructure.

[0092] Wafers, or carriers, are thin, supporting elements made of thermoplastic material. Wafers can include a variety of different structures and materials, including freestanding or unlaminated films, films with removable protective sheets, films with outer, permanent protective coatings or supporting plastic layers, and laminated films and wafers.

[0093] The wafer may be a preformed film or a stack of multiple coatings supported by the film. The coatings may be selected from, but are not limited to, anti-reflective coatings, anti-fouling topcoats, abrasion- and / or scratch-resistant coatings, impact-resistant coatings, polarizing coatings, photochromic coatings, colored coatings, printed layers, and anti-static coatings. The production of such coatings and coated wafers is described in WO 2008 / 015223 and U.S. Pat. No. 6,562,466, which are incorporated herein by reference. The coatings are applied to the surface of the wafer in the reverse order of the desired coating stack on the substrate.

[0094] Examples of thermoplastic (co)polymers that can be used to manufacture the present wafers include polysulfones, aliphatic poly(meth)acrylates (e.g., polymethyl methacrylate), polyethylene, polypropylene, polystyrene, SBM (styrene-butadiene-methyl methacrylate) block copolymers, polyphenylene sulfide, arylene polyoxides, polyimides, polyesters, polycarbonates (e.g., bisphenol A polycarbonate), PVC, polyamides (e.g., nylon), cellulose acetate butyrate, cellulose acetate, and cellulose triacetate, other copolymers thereof, and mixtures thereof. The microstructured wafer is preferably manufactured from polycarbonate. Preferably, the wafer is manufactured from a non-elastomeric material.

[0095] If the curable composition used is thermally cured, the material of the wafer must be selected to withstand the curing temperature.

[0096] Generally, the wafer has a thickness of 0.25 to 5 mm, preferably 0.5 to 4 mm, more preferably 1 to 3 mm, and even more preferably 1.5 to 2 mm.

[0097] By "inner surface of wafer" is meant the major surface of the wafer that will come into contact with the curable composition that forms the polythiourethane-based substrate during the present method.

[0098] The inner surface of the microstructured wafer may be concave or convex, depending on whether the wafer will be overmolded onto a concave or convex surface of the polythiourethane-based substrate in the final optical article.

[0099] The working surface of the wafer (its inner surface) has a relief structured according to a pattern, in other words a microstructured surface, which gives the final optical article an optical surface with properties imparted by the microstructure, such as properties to prevent the progression of myopia or hyperopia. Various techniques for obtaining microstructured mold parts are disclosed in WO 99 / 29494.

[0100] In one embodiment of the present invention, the microstructure comprises a plurality of lenslets, which may form ridges and / or depressions in the major surface on which they are disposed, and which may have a round or polygonal, e.g., hexagonal, outer shape.

[0101] In one embodiment, the inner surface of the wafer defines a plurality of recesses and / or a plurality of protrusions.

[0102] More specifically, the lenslets may be microlenses, such that the microstructure includes a plurality of microlenses. The microlenses may be spherical, toric, or have an aspherical shape, and may or may not be axisymmetric. The microlenses may have monofocal, astigmatic power, or non-focal.

[0103] In a preferred embodiment, the lenslets or microlenses can be used to arrest the progression of myopia or hyperopia, where the resulting polythiourethane-based substrate bonded to the microstructured wafer provides a refractive power that corrects myopia or hyperopia, with the microlenses or lenslets providing a refractive power greater than that of the polythiourethane substrate if the wearer is myopic or less than that of the polythiourethane substrate if the wearer is hyperopic, respectively.

[0104] In one embodiment, the inner surface of the wafer has at least one geometrically defined surface that forms a Fresnel lens.

[0105] The lenslets or microlenses may be Fresnel structures, diffractive structures defining Fresnel structures, permanent technological protuberances, or phase-shifting elements. They may also be refractive optical elements such as microprisms, light-dispersive optical elements such as small protrusions or cavities, or any type of element that creates irregularities on a substrate. They may be π-Fresnel lenslets, as described in U.S. Patent Application Publication No. 20211 / 09379, i.e., Fresnel lenslets whose phase function has a π phase step at the nominal wavelength, as opposed to single-focus Fresnel lenses whose phase step is a multiple of 2π. Such lenslets include structures with discontinuous shapes. In other words, the shape of such structures can be described by an elevation function in terms of distance from the base level of the main surface of the optical article to which the lenslet belongs, where the function exhibits discontinuities or its derivative exhibits discontinuities.

[0106] The lenslets may have a contour shape that can be inscribed in a circle having a diameter of 0.5 micrometers (μm) or more and 1.5 millimeters (mm) or less.

[0107] The lenslets may have a height of at least 0.1 μm and at most 50 μm, the height being measured in a direction perpendicular to the major surface on which the lenslets are disposed.

[0108] The inner surface of a wafer bearing a microstructure can be defined as the surface that contains the center points of any microstructures, and can be planar, spherical, spherocylindrical, or even more complex. This major surface can be an imaginary surface when the microstructures are embedded in a lens, or it can be close to or the same as the physical outer surface of the lens when the microstructures are not embedded. The height of the microstructure can then be determined by using a local normal axis to this major surface and calculating, for each point of the microstructure, the difference between the maximum positive deviation and the minimum negative deviation from the major surface along this axis.

[0109] The lenslets may have a periodic or quasi-periodic layout, but may also have random positions. Typical layouts of lenslets may be a honeycomb layout with a constant grid step, a grid of multiple concentric rings, or a continuous grid with no spaces between the microstructures, for example.

[0110] These structures can modify an optical wavefront in intensity, curvature, or light deflection, where the wavefront intensity is configured such that the structures can be absorptive and can locally absorb wavefront intensity in the range of 0% to 100%, the curvature is configured such that the structures can locally modify wavefront curvature in the range of ±20 diopters, and the light deflection is configured such that the structures can locally scatter light at angles in the range of ±1° to ±30°.

[0111] The distance between the structures may range from 0 (adjacent) to 3 times the structures (distinct microstructures).

[0112] Usually, microstructures, especially for myopia control, The microstructures include optical elements having a height of at least 0.1 μm or greater, preferably the following values ​​or greater: 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 (micrometers), measured at the surface of the lens when the microstructures are located at an interface microstructure / air or an internal interface within the optical element.

[0113] The microstructure may include a cylindrical annular refractive element.

[0114] The wafer may be treated to improve adhesion to the polythiourethane-based material, including mechanical roughening, physical cleaning, chemical surface modification, and plasma activation.

[0115] A preferred treatment is a chemical treatment that involves immersing the wafer in a basic or acidic solution, such as, but not limited to, NaOH, KOH, HCl, or HNO3 solution, rinsing, and drying. These acids or bases can be used at nominal concentrations of at least 0.001 N or higher. Treatment with a NaOH solution, typically a 5% NaOH solution, is preferred.

[0116] The mixing of the first component A and the second component B in step 4) can be carried out by any known mixing technique, such as that mentioned in U.S. Pat. No. 5,973,098. Preferably, the components A and B to be mixed are placed in a small reactor chamber and then mixed in 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, and even more preferably 0.1 Pa.s to 0.3 Pa.s.

[0117] During step 4), the mold cavity of the cast mold assembly is filled with a mixture of the first and second components A and B. The mold cavity is defined by the inner surface of the microstructured wafer and at least a portion of the mold part, which is typically made of inorganic glass, and can be held together using an annular fastener.

[0118] A cast mold assembly generally includes two mold parts that define two molding surfaces that cooperate to form a mold cavity when moved from an open position to a closed position. Each molding surface can be concave, convex, or planar, depending on the desired article shape. The molding surfaces can be convex, e.g., to form a concave substrate surface, or concave, e.g., to form a convex substrate surface.

[0119] Annular fastening elements, such as gaskets or adhesive tape, can be placed around and attached to the two mold pieces. A conventional method for filling such two-piece molds is by allowing a (liquid) optical material composition to flow into the mold cavity relative to the wafer through a pouring opening provided for this purpose in the closure member. In at least partially automated processes, the mold cavity to be filled is vertically aligned with a filling device adapted to deliver a specific amount of molding material through a nozzle.

[0120] In a first embodiment, step 4) comprises placing the wafer having the microstructure in a molding cavity of a cast mold assembly, the cast mold assembly comprising the mold part, such that the outer surface of the wafer is in contact with a surface, i.e., molding surface, of the cast mold assembly. In this embodiment, the wafer is placed in an empty cavity of the cast mold assembly, which is typically a two-part cast mold assembly, the first part of which is the mold part and the second part of which is the second mold part.

[0121] In a second embodiment, as shown in Figure 1, step 4) is performed using a two-part casting mold assembly, the first part of which is the mold part 4 and the second part of which is the microstructured wafer 1. In other words, in this embodiment, a microstructured wafer is used as the mold part. Figure 1 also shows tape 2 used to secure the two mold parts together, and a mixture 3 of first component A and second component B poured into the casting cavity.

[0122] In a third embodiment, step 4) comprises placing the microstructured wafer in a molding cavity of a cast mold assembly, the cast mold assembly comprising the mold part, such that the outer surface of the wafer does not contact a surface, i.e., molding surface, of the cast mold assembly. In this embodiment, the wafer is placed in an empty cavity of a cast mold assembly, which is typically a two-part cast mold assembly, the first part of which is the mold part and the second part of which is a second mold part.

[0123] In this third embodiment of the invention, a first volume (first mold cavity) can be defined between the inner surface of the microstructured wafer and a first mold surface of a first mold part, and a second volume (second mold cavity) can be defined between the outer surface of the wafer and a second mold surface of a second mold part. The two volumes can be filled with the same mixture or with the same or different mixtures of polymerizable compounds having the same or different refractive indices. Typically, the second volume is filled with the same mixture of first component A and second component B as the first volume. Thus, after curing, the wafer is sandwiched between two substrates: a first substrate bonded to the microstructured (inner) side of the wafer, and a second substrate bonded to the other (outer) side of the wafer, which can optionally have a microstructure that is the same as or different from the inner microstructure.

[0124] Depending on the desired properties of the resulting optical material, the optical material composition may be degassed under vacuum and / or filtered under pressure or vacuum before being poured into the mold assembly.

[0125] After the composition is poured, the casting mold assembly, preferably a lens casting mold assembly, can be heated in an oven or a water-immersed heater according to a predetermined temperature program to cure the resin within the mold assembly. The resin molded article may be annealed, if desired.

[0126] Step 5) of curing the mixture to provide a polythiourethane-based substrate adhered to the microstructured wafer can be carried out in the presence of a catalyst and can be carried out using any known polymerization technique, particularly thermal polymerization, including infrared heating, or radiation polymerization. The curing time for step 5) 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.

[0127] This process limits the diffusion of the polymerizable compound into the matrix of the wafer, thereby preserving the integrity of the microstructure design. Preferably, the compound from the mixture prepared in step 4) does not diffuse into the microstructured wafer during steps 4) and 5).

[0128] As explained above, using monomers to cast wafers to become an integral part of the final polythiourethane-based substrate, as in prior art processes, creates incompatibility problems, causing swelling of the wafer and resulting haze at the polymer interface.

[0129] Without wishing to be bound by any theory, the inventors believe that polythiourethane prepolymers with isocyanate or isothiocyanate end groups, which are larger molecules than the corresponding isocyanate or isothiocyanate monomers, are prevented from penetrating the wafer network, resulting in a transparent final product. The prepolymers (or oligomers) also reduce shrinkage of the polythiourethane matrix compared to standard monomers, resulting in less stress on the wafer. Low molecular weight, aromatic monomers such as isocyanates and isothiocyanates are believed to be stress cracking agents for the wafer matrix.

[0130] In step 6) of the method, as shown in Figure 2, after the resin has been molded onto the wafer, the cured polythiourethane-based substrate 5 adhered to the microstructured wafer 1 is recovered from the mold assembly. The overmolded substrate portion typically has a thickness greater than 2 mm, preferably greater than 3 mm.

[0131] The method can be used to produce a finished lens where both sides are of the required geometry, or to produce a semi-finished lens where one side still needs to be surfaced to the required geometry.

[0132] The article obtained from this method has satisfactory color properties, which can be quantified by the yellowness index Yi. The whiteness of the optical material of the present invention can be quantified by colorimetric measurements based on the CIE tristimulus values ​​X, Y, and Z, as described in standard ASTM E313, for example, with an illuminant C observer at 2°. The optical material according to the present invention preferably has a low yellowness index Yi, i.e., a yellowness index YI of less than 10, more preferably less than 8, and even more preferably less than 6, when measured according to the above standard. The yellowness index Yi is calculated according to ASTM method E313 according to the relationship Yi=(127.69X-105.92Z) / Y, where X, Y, and Z are the CIE tristimulus values.

[0133] The haze value of the polythiourethane-based substrate with the microstructured wafer bonded thereto, as determined according to standard ASTM D1003-00, is 6% or less, more preferably 5% or less, indicating a high level of transparency. Haze is preferably measured on a 2 mm thick sample.

[0134] The Tv coefficient, also known as the "luminous transmittance" of a system, is defined in ISO standard 13666:1998 and measured according to ISO standard 89803. It is defined as the average over the wavelength range 380-780 nm, weighted according to the eye's sensitivity in each wavelength range, and is measured under D65 lighting conditions (daylight).

[0135] The luminous transmittance Tv in the visible light range of the polythiourethane-based substrate to which the microstructured wafer is bonded, determined according to standard ISO 8980-3, is 74% or more, more preferably 78% or more or 80% or more.

[0136] In some embodiments, the method does not include depositing a catalyst composition onto an interior surface of the mold part and / or onto at least one surface of the light filtering element after it has been placed within the mold cavity.

[0137] In some embodiments, the method does not include depositing a catalyst composition on a surface of a wafer having a microstructure.

[0138] In some embodiments, the method does not include depositing a catalyst composition on the interior surface of the wafer having the microstructure.

[0139] In some embodiments, the method does not include depositing a catalyst composition on an outer surface of the wafer having a microstructure.

[0140] In some embodiments, the method does not include depositing a catalyst composition within the mold cavity prior to placing the polymerizable composition within the mold cavity.

[0141] In some embodiments, the method does not include depositing a catalyst composition on the interior surface of at least one mold.

[0142] In some embodiments, the method does not include depositing a catalyst composition on at least one of the surfaces of the light filtering element.

[0143] In some embodiments, the method does not include depositing a catalyst composition onto at least one surface of the light filtering element that is then placed within the mold assembly.

[0144] In one embodiment, the method according to the present invention does not include a method for rapidly curing a transparent casting substrate that can be used to manufacture an optical article such as an ophthalmic lens, and the method comprises: - providing a rapidly room temperature polymerizable composition; - providing a catalyst composition; - providing a mold assembly including two non-sealing molds each having an inner surface and an outer surface, and optionally providing a light filtering element disposed or configured to be disposed between the two molds; a catalyst composition, - on at least one inner surface of the mold, and / or - on at least one of the surfaces of the light filtering element that will be subsequently placed in the mold assembly. and depositing the - closing the mold assembly so that the interior surfaces of the molds together form a molding cavity; - filling a molding cavity of a mold assembly that already contains a catalyst composition deposited on at least one interior surface of the mold with a rapidly room-temperature polymerizable composition; - curing the filled mold assembly to obtain a transparent solid substrate, a) a first step for polymerizing said composition at room temperature to obtain a gel; b) a second step of post-curing the gel to obtain a transparent solid substrate; and - recovering the transparent solid substrate from the mold assembly; Includes:

[0145] The following examples illustrate the invention in a more detailed but non-limiting manner. Unless otherwise specified, all thicknesses disclosed in this application refer to physical thicknesses. [Example]

[0146] Chemicals used The optical material was prepared from a composition containing polymerizable monomers, Zelec N® (CAS 3896-11-5) as a mold release agent, and a catalyst solution containing 8.5% KSCN (CAS 333-20-0), 34.84% 18-crown-6 (CAS 17455-13-9), and 56.66% mercaptoethanol (CAS 60-24-2). 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).

[0147] Evaluation of the cured lens The following test procedures were used to evaluate optical articles made in accordance with the present invention: Several samples for each system were prepared for measurement, and the reported data was calculated using an average of the various samples.

[0148] Colorimetric measurements of hue angle h, chroma C*, and b* were performed in the international colorimetric CIE (L*, a*, b*) space using a Zeiss spectrophotometer, in transmission mode, at an incidence angle of 0°, considering standard illuminant D65 and a standard observer at 10°.

[0149] The luminous transmittance Tv in the visible light spectrum was measured in transmission mode (angle of incidence: 0°) from the wearer's viewing angle using a Hunter Cary 4000 spectrometer, with the (concave) rear surface of the lens (2 mm thick at the center) facing the detector and light incident on the front surface of the lens. Tv was measured under D65 lighting conditions (daylight).

[0150] Haze was measured according to standard ASTM D1003-00 with a Hazegard XL-211 Plus instrument from BYK-Gardner as disclosed in WO 2012 / 173596. Haze is a measure of the percentage of transmitted light that is scattered more than 2.5° from the axis of the incident light, so the lower the haze value, the less cloudy it is.

[0151] The yellowness index Yi of the prepared lenses was calculated as described above by measuring the CIE tristimulus values ​​X, Y, Z using the spectrophotometer described above on a white background, such as that described in standard ASTM E 313-05, by reflection measurement, with the front (convex) side of the lens facing the detector and light incident on said front surface. This method of measuring Yi from the viewing angle of the observer is closest to the actual wearing situation.

[0152] Preparation of Polythiourethane Prepolymer A1 with Isocyanate End Groups (Component A of Examples 1 and 3) A reactor equipped with a condenser, a heat probe, and an agitator was charged with a predetermined amount of polyisocyanate monomer m-xylylene diisocyanate (XDI) and heated to 120°C. 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol was then introduced and mixed with the polyisocyanate in an amount that resulted in an 8:1 molar ratio NCO / SH of isocyanate functional groups to thiol functional groups (89.7% polyisocyanate, 10.3% polythiol). The mixture was heated for 3.5 hours. The resulting prepolymer A1 was then cooled to approximately 35°C, transferred to a suitable drum, and stored in a refrigerator under an inert gas (nitrogen or argon) stream. The viscosity of the final prepolymer with isocyanate end groups at 25°C was approximately 0.1 Pa.s. Prepolymer A1 was prepared without the use of a catalyst.

[0153] Preparation of Polythiourethane Prepolymer B1 with Thiol End Groups (Component B of Examples 2 and 3) A reactor equipped with a condenser, a heat probe, and an agitator was charged with a predetermined amount of polythiol monomer, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol, and heated to 95°C. Xylylene diisocyanate was then charged and mixed with the polythiol in an amount to provide a molar ratio of thiol functional groups to isocyanate functional groups, SH / NCO, of 8:1. The mixture was heated for 3.5 hours. The end of the reaction was indicated by the temperature reaching a peak and then returning to 95°C (±2°C). The resulting prepolymer B1 was then cooled to approximately 35°C, transferred to a suitable drum, and stored in a refrigerator under an inert gas (nitrogen or argon) flush. The viscosity of the final prepolymer with thiol end groups at 25°C was approximately 0.5 Pa.s. Prepolymer B1 was prepared without the use of a catalyst.

[0154] Mold Assembly A two-part casting mold assembly was assembled using tape to a center thickness of 2 mm.

[0155] The two-part casting mold assembly is shown schematically in Figure 1. The first part of the mold assembly (the back part) was a 71 mm diameter inorganic glass mold part, and the second part of the mold assembly (the front part / top mold) was a microstructured polycarbonate wafer (3.25 mm base, i.e., 76 mm, surfaced to a 2 mm center-thick plano lens—71 mm; front radius was 167.81 mm) with a microlens pattern on the back (concave) surface for myopia suppression. This was pre-cleaned with isopropyl alcohol to remove any dust or contaminants.

[0156] The wafer was placed on top with its concave surface bearing the microstructure facing downwards, and a mating glass mold part was placed on the bottom with its concave surface facing downwards.

[0157] Preparation of transparent polythiourethane casting substrates Example 3 Prepolymers A1 and B1 were prepared as described above. A predetermined amount of cooled prepolymer A1 was mixed with a predetermined amount of Zelec UN®. This mixture was stirred at 15°C and degassed for 1 hour, then degassed for 15 minutes without stirring to form component A. A predetermined amount of prepolymer B1 was mixed with a predetermined amount of the above-mentioned catalyst solution (KSCN, 18-crown-6, 2-mercaptoethanol). This mixture was stirred at 15°C and degassed for 1 hour, then degassed for 15 minutes without stirring to form component B. Components A and B were then mixed in a small reactor with stirring and degassing for 5 minutes at room temperature, then 2 minutes at 15°C, to prevent gelation. The resulting mixture had a viscosity of approximately 0.1-0.3 Pa.s at 25°C. After mixing was complete, the mixture was filled into a mold assembly using a clean syringe. The assembled mold was held at room temperature for 10 minutes and then placed in a preheated convection oven at 120°C. The mixture began to gel in the mold assembly. The polymerization reaction was carried out by leaving the mold assembly in the oven at 120°C for 3 hours. The mold assembly was then allowed to cool to 65°C.

[0158] In the context of the present invention, gel refers to a reaction product of components A and B in which the conversion of reactive functional groups is significantly high, for example, in the range of 50-80%, preferably about 70%.

[0159] The mold assembly was then disassembled to yield lenses with a center thickness of 2 mm comprising an overmolded body of polythiourethane transparent thermoset substrate. The lenses were annealed at 120°C for 1 hour. The lenses were cleaned by immersion in a surfactant solution and sonication, then rinsed and dried. They had a refractive index of 1.67 and were free of optical defects such as striations.

[0160] The polycarbonate wafer used as the front surface mold now became an integral part of the final lens and could not be removed therefrom.

[0161] Example 1 The lenses of Example 1 were prepared similarly to Example 3, except that Component B contained a predetermined amount of the polythiol monomer 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol and a predetermined amount of the catalyst solution described above (KSCN, 18-crown 6, mercaptoethanol).

[0162] Comparative Example 2 The lens of Comparative Example 2 was prepared in the same manner as Example 3, except that Component A contained a predetermined amount of m-xylylene diisocyanate, a polyisocyanate monomer, and a predetermined amount of Zelec UN®.

[0163] Comparative Example 3 Attempts were made to prepare a mixture of at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer and inject it into a casting mold assembly, but the monomers reacted within 10 minutes at room temperature to form a gel that could not be introduced into the mold cavity.

[0164] Composition and Results The amounts (parts by weight) of the various compounds used and the results of their characterization are shown in Table 1:

[0165] [Table 1]

[0166] Comparison of Example 1 and Comparative Example 2 shows that when prepolymer A1 having isocyanate or isothiocyanate end groups is used instead of monomer A2 having isocyanate or isothiocyanate end groups, the transmittance (see Figure 4), yellowness index, and transparency (see Figure 3) are improved.

[0167] Lenses obtained by curing compositions containing prepolymer A1 having isocyanate or isothiocyanate terminal groups and either prepolymer B1 having thiol terminal groups (Example 3) or monomer B2 having thiol terminal groups (Example 1) all exhibited satisfactory yellowness index, transmittance, and clarity. The use of a mixture of two prepolymers in Example 3 can further improve the haze level, yellowness index, and transmittance compared to Example 1 or Comparative Example 2, which use only one prepolymer.

[0168] Without wishing to be bound by any theory, the inventors believe that casting a prepolymer A1 having isocyanate or isothiocyanate end groups can significantly reduce wafer swelling.

Claims

1. 1. A method for curing a polythiourethane-based casting substrate, comprising the steps of: 1), 2), 3), 4), 5) and 6), or 1′), 2′), 3), 4), 5) and 6): 1) providing a first component A comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups of formula -NCX, where X is O or S, said prepolymer A1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; 2) providing a second component B comprising a polythiourethane prepolymer B1 having thiol end groups, said prepolymer B1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; or 1') providing a first component A comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups of formula -NCX, where X is O or S, said prepolymer A1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; 2') providing a second component B comprising at least one polythiol monomer B2; 3) providing a microstructured thermoplastic wafer, said wafer having an inner surface and an outer surface, said inner surface having a microstructure; 4) mixing the first and second components A and B together and filling the resulting mixture into a mold cavity, the mold cavity being defined by the inner surface of the microstructured wafer and at least a portion of a mold part; 5) curing the mixture to obtain a polythiourethane-based substrate; and 6) recovering the polythiourethane substrate adhered to the microstructured wafer; A method comprising:

2. Steps 1) and 2) below: 1) providing a first component A comprising a polythiourethane prepolymer A1 having isocyanate or isothiocyanate end groups of formula -NCX, where X is O or S, said prepolymer A1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; 2) providing a second component B comprising a polythiourethane prepolymer B1 having thiol end groups, said prepolymer B1 being prepared from at least one polythiol monomer and at least one polyisocyanate or polyisothiocyanate monomer; The method of claim 1 , comprising:

3. 3. The method of claim 1 or 2, wherein the resulting mixture of step 4) comprises at least one catalyst.

4. The method according to any one of claims 1 to 3, wherein the curing time of step 5) is less than 10 hours, preferably less than 5 hours.

5. The method according to any one of claims 1 to 4, wherein the amounts of the polyisocyanate monomer or polyisothiocyanate monomer and the polythiol monomer are adjusted so that 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 in the preparation of the polythiourethane prepolymer A1, and / or the amounts of the polyisocyanate monomer or polyisothiocyanate monomer and the polythiol monomer are adjusted so that 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 in the preparation of the polythiourethane prepolymer B1, and X is O or S.

6. The method according to any one of claims 1 to 5, wherein the substrate is an optical lens substrate.

7. The method of any one of claims 1 to 6, wherein the microstructure comprises a plurality of microlenses.

8. The method of any one of claims 1 to 7, wherein the inner surface of the wafer defines a plurality of recesses or a plurality of protrusions.

9. The method of any one of claims 1 to 8, wherein the microstructured wafer is made of polycarbonate.

10. 10. The method of any one of claims 1 to 9, wherein the haze value of the polythiourethane-based substrate to which the microstructured wafer is bonded is 6% or less, determined according to standard ASTM D1003-00.

11. 11. The method according to any one of claims 1 to 10, wherein the polythiourethane-based substrate to which the microstructured wafer is bonded has a luminous transmittance Tv in the visible light range of 74% or more, determined according to standard ISO 8980-3.

12. 12. The method of any one of claims 1 to 11, wherein compounds from the mixture prepared in step 4) do not diffuse into the microstructured wafer during steps 4) and 5).

13. 13. The method of any one of claims 1 to 12, wherein step 4) comprises placing the microstructured wafer in a molding cavity of a cast mold assembly such that an outer surface of the wafer contacts a surface of the cast mold assembly, the cast mold assembly containing the mold part.

14. 13. The method of any one of claims 1 to 12, wherein step 4) is performed using a two-part cast mold assembly, a first part of which is the mold part and a second part of which is the microstructured wafer.

15. 15. The method of any one of claims 1 to 14, which does not include depositing a catalyst composition onto an inner surface of a mold part and / or onto at least one surface of the light filtering element after it has been placed in the mold cavity.

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