Optical materials derived from prepolymers obtained from free heterobifunctional alkyne compounds

Abstract

The invention relates to a polymerizable composition comprising a) at least one polyiso (thio) cyanate and at least one prepolymer having thiol end groups, obtained from the reaction of a mixture of at least one polythiol and at least one polymerizable compound of formula (I), or b) a prepolymer of at least one polythiol and at least one isocyanate or isothiocyanate end group having the formula-NCX, where X is O or S, obtained from the reaction of a mixture of at least one polyiso (thio) cyanate and at least one polymerizable compound having the formula (I), where R1 and R2 represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero) aryl group, or R1 and R2 together form a divalent group having the formula-R1-R2-, where-R1-R2-represents a substituted or unsubstituted alkylene group, Z represents OH, SH, NH2 or NHR4, where R4 represents a substituted or unsubstituted alkyl or (hetero) aryl group, and R3 represents a hydrogen atom, a substituted or unsubstituted alkyl group, (hetero) aryl group, or a CR '1R' 2Z 'group, where R' 1, R '2 and Z' are defined as R1, R2 and Z. (Formula I))

Description

[0001] The present invention relates to an optical material having improved thermo-mechanical properties, in particular impact resistance, which can be particularly used in optical substrates, such as ophthalmic lenses, generally having a medium or high refractive index. The present invention also relates to a polymerizable composition, to a pre-polymer, and to a method of manufacturing an optical material.

[0002] BACKGROUND AND SUMMARY OF THE INVENTION

[0003] Plastic materials have been developed as substitutes and replacements for glass in applications such as optical lenses, optical fibers, windows, and in the automotive, marine, and aerospace industries. Organic polymeric materials are advantageous in terms of light weight, impact resistance, ease of molding, and dyeability compared to inorganic glasses.

[0004] Optical elements have been developed from various durable organic polymers, including polythiourethanes obtained by condensation of polyis(thio)cyanate and polythiol monomers, disclosed for example in applications WO 00 / 26272, US 2007 / 098999, WO 2021 / 182526, EP 3916470, and EP 3919967.

[0005] Polythiourethane materials exhibit relatively high refractive indices and are of primary interest because this property allows the manufacture of optical articles such as lenses having a lower thickness for an equivalent corrective power. However, most of the resulting polythiourethane polymers exhibit poor mechanical properties, such as low glass transition temperature and low impact resistance.

[0006] US 2016 / 376453 discloses a curable composition comprising a polythiol component, an olefin- and / or acetylene-containing component, and an epoxy-containing component. The polythiol component can be derived from a thiol-containing terpene or terpenoid, a thiol-containing cyclic olefin, a thiol-containing polycyclic olefin, a straight-chain olefin, a thiol-containing alkyne, a thiol-containing unsaturated fatty acid, a thiol-containing unsaturated fatty ester, or a thiol-containing polyolefin. The cured composition is used to manufacture a cell phone case or a foamed polystyrene foam. However, three different chemicals need to be synthesized and then blended to obtain the polymerizable composition.

[0007] US 2008 / 0125570 discloses an optical article comprising the reaction product of (A) a reactive compound comprising a material having a functional group reactive with active hydrogen such as an isocyanate group; (B) a thioether-functional oligomeric polythiol prepared by reacting together a compound having at least two thiol functional groups, a hydroxyl-functional compound having a triple bond functional group; and a compound having at least two double bonds. The hydroxyl-functional compound having a triple bond functional group is used in a high amount to produce a polymeric material (stoichiometric amount relative to other monomers), and thus constitutes the backbone of the network.

[0008] EP 3257876 describes a polymerizable composition comprising 100 parts by weight of a terminal diacetylene compound and 25-75 parts by weight of a polythiol for obtaining a material having a high refractive index. Since diacetylene is used in a high amount, the glass transition temperature of the material is expected to be very low.

[0009] EP 2980113 discloses a polymerizable composition for optical materials comprising a polythiol compound and a bifunctional compound having a carbon-carbon triple bond and at least one group selected from an isocyanate group and an isothiocyanate group, such as propargyl isocyanate.

[0010] JP 2019 / 026755 and JP 2019 / 142849 describe an optical material composition containing a compound having two or more acetylene groups at terminal positions, which compound is polymerizable with a polythiol compound.

[0011] Therefore, there is a need in the art to develop a polymeric material having a sufficient refractive index and glass transition temperature, good impact resistance / strength for practical use in optical articles at a reasonable cost.

[0012] The present invention relates to a polymerizable composition comprising:

[0013] a) at least one polyisocyanate or polyisothiocyanate and a component B comprising at least one prepolymer having thiol end groups, said component B being obtained from the reaction of at least one polythiol with a mixture of at least one polymerizable compound of formula (I), or

[0014] b) at least one polythiol and a component A comprising at least one prepolymer having an isocyanate or isothiocyanate end group of formula -NCX, wherein X is O or S, said component A being obtained from the reaction of at least one polyisocyanate or polyisothiocyanate with a mixture of at least one polymerizable compound of formula (I),

[0015]

[0016] wherein R 1 and R 2 independently of one another represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R 1 and R 2 together form a divalent group of formula -R 1 -R 2 -, wherein -R 1 -R 2 - represents a substituted or unsubstituted alkylene group, and Z represents OH, SH, NH2or NHR 4 wherein R 4 represents a substituted or unsubstituted alkyl group or a (hetero)aryl group, and R 3 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or a group of formula:

[0017]

[0018] wherein R’ 1 and R’ 2 independently of one another represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R’ 1 and R’ 2 together form a divalent group of formula -R’ 1 -R’ 2 -, wherein -R’ 1 -R’ 2 - represents a substituted or unsubstituted alkylene group, and Z’ represents OH, SH, NH2or NHR’ 4 wherein R’ 4 represents a substituted or unsubstituted alkyl group or a (hetero)aryl group,

[0019] wherein the polymerizable composition is obtained from polymerizable compounds, such that the polymerizable compounds used for the preparation of the prepolymer and the polymerizable compounds added to the prepolymer in the polymerizable composition are adapted such that the molar ratio of SH / alkynyl groups present in all the polymerizable compounds is used in an amount higher than or equal to 7, and

[0020] the polymerizable composition is obtained from polymerizable compounds, such that the polymerizable compounds used for the preparation of the prepolymer and the polymerizable compounds added to the prepolymer in the polymerizable composition are adapted such that the molar ratio of NCX / alkynyl groups present in all the polymerizable compounds is used in an amount higher than or equal to 6, X being O or S.

[0021] The inventors of the present invention have discovered that acetylene compounds of Formula (I) having at least one group with active hydrogen can be used as modifiers in standard polythiourethane compositions containing polythiols and poly(iso(thio)cyanates). This addition of acetylene comonomer allows standard polythiourethane resins with poor impact resistance to meet FDA impact resistance requirements without the need to use special coatings or plasticizers that provide this property, while in some embodiments improving the glass transition temperature and / or the elastic modulus of the material.

[0022] The present invention provides polythiourethane polymer networks modified by increased crosslinking from thiol-alkyne reaction providing thioether functionality due to specially designed starting materials that can copolymerize with polythiols and poly(iso)thiocyanates and can be partially cured by photochemical methods. Improving the impact resistance of the material by increasing crosslinking with acetylene modifiers is an innovative approach.

[0023] It has also been found that the introduction of acetylene comonomer reduces the reaction time to reach the specified level of conversion of polyisocyanate or polyisothiocyanate compounds in the optical material according to the invention.

[0024] The foregoing and other objects, features and advantages of the present invention will become apparent to those skilled in the art upon reading the following of the present invention, taken together with the accompanying drawings, in which Figure 1 represents the FTIR spectrum of the initial monomer formulation before reaction, and Figure 2 represents the FTIR spectrum of the polymer obtained after a certain reaction time. DETAILED DESCRIPTION

[0025] The terms "comprise" (and any grammatical variations thereof such as "comprises" and "comprising"), "have" (and any grammatical variations thereof such as "has" and "having"), "contain" (and any grammatical variations thereof such as "contains" and "containing") and "include" (and any grammatical variations thereof such as "includes" and "including") are open-ended linking verbs. They are used to specify the presence of stated features, integers, steps or components or groups thereof but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. As a result, a method or step in a method that "comprises," "has," "contains" or "includes" one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements.

[0026] All numbers or expressions regarding amounts, ranges, response times, or the like that occur in the specification are to be understood to be prefaced by the term "about," unless otherwise explicitly indicated.

[0027] In the present specification, an optical article / material is understood to be transparent when viewing an image through said optical article does not perceive a significant loss of contrast, i.e. when an image formation through said optical article is obtained without adversely affecting the quality of the image. This definition of the term "transparent" can be applied to all objects defined as such in the present specification, unless otherwise indicated.

[0028] The optical material of the present application is an organic glass made of a thermosetting resin. The polymeric matrix of said material is obtained by polymerization of a polymerizable composition comprising: a) at least one polyisocyanate or polyisothiocyanate and a component B comprising at least one prepolymer having thiol end groups, said component B being obtained from the reaction of at least one polythiol with a mixture of at least one polymerizable compound of formula (I), or b) at least one polythiol and a component A comprising at least one prepolymer having isocyanate or isothiocyanate end groups of formula -NCX, wherein X is O or S, said component A being obtained from the reaction of at least one polyisocyanate or polyisothiocyanate with a mixture of at least one polymerizable compound of formula (I),

[0029] wherein R 1 and R 2 independently of one another represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R 1 and R 2 together form a divalent radical of formula -R 1 -R 2 - wherein -R 1 -R 2 - represents a substituted or unsubstituted alkylene group, Z represents OH, SH, NH2or NHR 4 wherein R 4 represents a substituted or unsubstituted alkyl group or a (hetero)aryl group, and R 3 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or a group of formula:

[0030] wherein R’ 1 and R’ 2 independently of one another represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R’ 1 and R’2 together form a divalent radical of formula -R' 1 -R' 2 - wherein -R' 1 -R' 2 - represents a substituted or unsubstituted alkylene group and Z' represents OH, SH, NH2or NHR' 4 wherein R' 4 represents a substituted or unsubstituted alkyl or (hetero)aryl group.

[0031] The optical material of the application can be used as a substrate of an optical article, preferably an optical lens or lens blank, more preferably an ophthalmic lens or lens blank, such as a plastic spectacle lens. It can also be used as a coating.

[0032] The term "ophthalmic lens" is intended to mean a lens adapted to be mounted in a spectacle frame to protect the eye and / or to correct vision. The lens can be chosen from afocal lenses, single- vision lenses, bifocal lenses, trifocal lenses, progressive lenses, piano lenses, solar lenses and Fresnel lenses or any other type of lens having a discontinuous surface.

[0033] Although ophthalmic optics is the preferred field of the application, it is understood that the application can be applied to other types of optical articles, such as for example lenses for optical instruments in photography or astronomy, optical sighting lenses, eye visors, optical devices of illumination systems, screens, glazing, windshields, sports visors, face shields, goggles, optical coatings or adhesives, etc.

[0034] If the optical article is an optical lens, it can be coated on one or more of its front major surface, back major side or both with one or more functional coatings. As used herein, the back of the substrate is intended to mean the face that is closest to the wearer's eye when using the article. The back is usually a concave face. Conversely, the front of the substrate is the face that is farthest from the wearer's eye when using the article. The front is usually a convex face. The optical article can also be a piano article.

[0035] In the sense of the present application, the substrate is understood to mean the uncoated substrate and usually has two major faces. The substrate can in particular be made of the optical material of the application having the shape of an optical article, such as an ophthalmic lens intended to be mounted in a spectacle. In this context, the term "substrate" is understood to mean the base constitutive material of the optical article and more particularly of the optical lens. Such material can act as a support for the stack of one or more coatings or layers.

[0036] From the point of view of reducing the thickness of the lens, plastic materials having a high refractive index are desirable. The optical material according to the application preferably has a refractive index higher than or equal to 1.50, more preferably 1.52 or more or 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, 1.67 or more, 1.70 or more, or 1.72 or more, and it is preferably 1.80 or less, more preferably 1.75 or less. Unless otherwise specified, the refractive index mentioned in the present application is expressed at 25°C, at a wavelength of 550 nm.

[0037] The refractive index of the optical material can be adjusted by adapting the structure of the polymerizable precursor, in particular the weight amount represented by the sulfur atoms in the monomers, typically the polythiol monomers or the bifunctional compounds of formula (I). The refractive index of the material can also be increased by the presence of one or more aromatic groups in the structure of at least one polymerizable precursor.

[0038] In one embodiment, the optical material according to the application is thin, i.e. it preferably has a central thickness of 2 mm or less, more preferably 1.5 mm or less and even better 1.2 mm or 1.1 mm or less.

[0039] The optical material according to the application preferably has a glass transition temperature higher than or equal to 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C. It is preferably lower than or equal to 200°C. The glass transition temperature can be measured by DMA (Dynamic Mechanical Analysis).

[0040] The optical material according to the application preferably has an elastic modulus E (or Young's modulus, or storage modulus, or tensile elastic modulus) higher than or equal to 2.5, 3, 3.2, 3.4 or 3.6 GPa. The elastic modulus E of the material assesses the ability of the material to deform under the action of an applied force. It can be measured by DMA (Dynamic Mechanical Analysis).

[0041] The optical material according to the application preferably has a relative light transmission factor Tv in the visible spectrum higher than or equal to 70%, preferably higher than or equal to 75%, more preferably higher than or equal to 80%, and better still higher than or equal to 85%.

[0042] The Tv factor, also called the "light transmittance" of the system, is as defined in ISO standard 13666:1998 and measured according to standard ISO 8980-3. It is defined as the average transmittance in the 380-780 nm wavelength range, weighted according to the sensitivity of the eye at each wavelength of this range, and measured under D65 illumination conditions (daylight). The transmittance is expressed for an optical article of 2 mm thickness, measured at the center of the optical article and at normal incidence of the light beam (0° with the normal).

[0043] The optical material according to the application has satisfactory color properties, which can be quantified by the yellowness index Yi. The whiteness of the optical material of the application can be quantified by colorimetry, based on the CIE tristimulus values X, Y, Z as described in standard ASTM E313, in the case of illuminant C observer 2°. The optical article according to the application preferably has a low yellowness index Yi, i.e. lower than 8, more preferably lower than 6, even better lower than 4, as measured according to the above-mentioned standard. The yellowness index Yi is calculated according to ASTM method E313 by the relation Yi = (127.69 X - 105.92 Z)) / Y, where X, Y and Z are the CIE tristimulus values.

[0044] The polymerizable composition yielding the optical material is obtained from three main components, i.e. a polythiol, a polyis(thio)cyanate and a heterobifunctional alkyne compound of formula (I) having at least one alkynylene-C≡C- group and at least one Z group bearing a heteroatom (O, S or N) and at least one active hydrogen atom.

[0045] In one embodiment, the compound of formula (I) and the polythiol are different compounds.

[0046] By convention, the compound of formula (I) is generally referred to as a bifunctional compound, but it can actually comprise more than two reactive functional groups, for example when at least one of its substituents R 1 , R 2 or R 3 comprises at least one reactive functional group.

[0047] In one embodiment, the polymerizable compound of formula (I) comprises less than two thiol functional groups, preferably 0 or 1 thiol functional group. In one embodiment, the polymerizable compound of formula (I) comprises less than two is(thio)cyanate functional groups, preferably no is(thio)cyanate functional group.

[0048] The polymerizable composition can be obtained from only one type of compound having formula (I), or from a mixture of compounds having formula (I) of different structures. As used herein, "polymerizable composition" without further details refers to a composition containing a prepolymer according to the present application and a complementary polymerizable compound.

[0049] The prepolymer is obtained from a non-stoichiometric blend of at least two monomers, the reaction of which yields an oligomer, in particular from a small amount of a given monomer in excess of another monomer.

[0050] The polymerizable composition according to the present application is obtained in two steps, comprising a step of preparing a prepolymer having is(thio)cyanate or thiol end groups, and a step of adding to said prepolymer a complementary polymerizable compound. Depending on the nature of the end groups of the prepolymer, the complementary polymerizable compound is a polythiol or a polyis(thio)cyanate.

[0051] Thus, the prepolymer according to the present application is a polymerizable compound (adduct) intended to further react with a complementary polymerizable compound, generally a monomer, in order to provide a final optical material.

[0052] In a first main embodiment of the present application, the prepolymer having thiol end groups is prepared from the reaction of a mixture of at least one polythiol and at least one polymerizable compound having formula (I), the former being used in excess. Thus, component B comprises oligomers resulting from thiol-yne condensation and un-polymerized initial monomers, if any, which are mainly polythiols.

[0053] In a second main embodiment of the present application, the prepolymer having isocyanate or isothiocyanate end groups is prepared from the reaction of a mixture of at least one polyis(thio)cyanate and at least one polymerizable compound having formula (I), the former being used in excess. Thus, component A comprises oligomers (resulting from the condensation of is(thio)cyanate and groups bearing active hydrogens) and un-polymerized initial monomers, if any, which are mainly polyis(thio)cyanates.

[0054] The polymerizable composition can comprise additional polymerizable compounds which are neither compounds of formula (I) according to the present application nor polythiols or polyis(thio)cyanates. In one embodiment, such additional polymerizable compounds (co-monomers) can be co-polymerized with at least one of the compounds of formula (I) according to the present application, polyis(thio)cyanates and polythiols. The above mentioned additional polymerizable compounds can also be used in the polymerizable composition forming the prepolymer according to the present application (having -SH or -NCX end groups), i.e. during the reaction of at least one polythiol with at least one polymerizable compound of formula (I) (first main embodiment of the present application) or during the reaction of at least one polyisocyanate or polyisothiocyanate with at least one polymerizable compound of formula (I) (second main embodiment of the present application).

[0055] The polythiols, polyis(thio)cyanates and compounds of formula (I) according to the present application preferably make up at least 50% by weight, more preferably at least 60%, 70%, 80%, 90%, 95%, 99%, or 100% by weight relative to the total weight of the polymerizable compounds used to prepare the polymerizable composition (i.e. the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to the prepolymer in the polymerizable composition).

[0056] In one embodiment, the polymerizable composition comprises less than 5% by weight, more preferably less than 4%, 3%, 2% or 1% by weight of polymerizable compounds having at least two C=C double bonds relative to the total weight of the polymerizable compounds present in the composition, even more preferably does not comprise any polymerizable compounds having at least two C=C double bonds. In one embodiment, the prepolymer according to the present application is not formed from polymerizable compounds having at least two C=C double bonds. In another embodiment, the prepolymer according to the present application is prepared using less than 5% by weight, more preferably less than 4%, 3%, 2% or 1% by weight of polymerizable compounds having at least two C=C double bonds relative to the total weight of the polymerizable compounds used to prepare the prepolymer.

[0057] Examples of polymerizable compounds which are neither compounds of formula (I) according to the present application nor polythiols or polyis(thio)cyanates include polyols, polyamines, epoxy-containing compounds.

[0058] In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that the polythiols represent from 35% to 70% by weight, more preferably from 38% to 65% by weight, 40% to 60% by weight, 42%-58% by weight, 44%-54% by weight, or 52% to 54% by weight, relative to the total weight of the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to said prepolymer in the polymerizable composition. In another embodiment, the polymerizable composition is obtained from polymerizable compounds such that the polythiols represent from 38% to 58% by weight, relative to the total weight of the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to said prepolymer in the polymerizable composition.

[0059] In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that the tri-thiols represent from 35% to 42% by weight and the tetra-thiols represent from 3% to 16% by weight, relative to the total weight of the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to said prepolymer in the polymerizable composition. In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that the polyis(thio)cyanates represent from 20% to 70% by weight, more preferably from 25% to 65% by weight, 30% to 60% by weight, 40%-50% by weight, 47%-55% by weight, or 42%-47.5% by weight, relative to the total weight of the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to said prepolymer in the polymerizable composition.

[0060] The compounds of formula (I) are used as modifiers in the preparation of polymerizable compositions obtained from polythiols and polyis(thio)cyanates as main components, which means that the backbone of the optical material according to the present application is a polythiourethane.

[0061] In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that the compounds of formula (I) represent from 0.15% to 4% or 5% by weight, more preferably from 0.2% to 3.5% by weight, 0.25% to 3% by weight, 0.25% to 2.5% by weight, 1% to 3% by weight, or 0.3% to 2% by weight, relative to the total weight of the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to said prepolymer in the polymerizable composition. When the amount of alkyne compounds of formula (I) is increased, the polymer network becomes richer in sulfide bonds resulting from the reaction of alkyne and thiol functional groups, which results in S-C bonds.

[0062] In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that the polyis(thio)cyanate and the polythiol represent from 80% to 99.85% by weight, more preferably from 85% to 99.85%, 90% to 99.85%, 95% or 96% to 99.85%, 96.5% to 99.8% by weight, 97% to 99.75% by weight, 97.5% to 99.75% by weight, or 98% to 99.7% by weight, relative to the total weight of the polymerizable compounds (used to prepare the prepolymer and the polymerizable compounds added to said prepolymer in the polymerizable composition).

[0063] In one embodiment, the polymerizable composition comprises from 35% to 65% by weight, more preferably from 40% to 60% by weight, even more preferably from 40% to 50% by weight, of the prepolymer according to the application, relative to the total weight of the polymerizable compounds present in said polymerizable composition.

[0064] In one embodiment, the polymerizable composition comprises from 35% to 65% by weight, more preferably from 40% to 60% by weight, even more preferably from 40% to 50% by weight, of the complementary polymerizable compound according to the application (which is either a polythiol or a poly(iso)thiocyanate), relative to the total weight of the polymerizable compounds present in said polymerizable composition.

[0065] The inventors surprisingly found that the use of even small amounts of the alkyne comonomer compound of formula (I) in the preparation of the modified polythiourethane material leads to a material with improved impact resistance compared to pure polythiourethane materials with low impact resistance.

[0066] Without wishing to be bound by any theory, the inventors believe however that the alkyne compound of formula (I), acting as a crosslinker in the polymer network, also introduces thioether bonds which impart greater flexibility to the polymer network compared to the pure polythiourethane matrix without the alkyne comonomer.

[0067] As demonstrated in the experimental part, the preparation of the polymerizable composition using amounts of the alkyne comonomer compound of formula (I) satisfying the SH / alkyne and NCX / alkyne molar ratios according to the application is beneficial for other thermo-mechanical properties of the optical material, i.e. increases its glass transition temperature and elastic modulus compared to the pure polythiourethane matrix.

[0068] However, below the SH / alkyne molar ratio according to the present application, i.e. when using too high amounts of the alkyne co-monomer compound of formula (I) to prepare the polymerizable composition, the glass transition temperature of the material is significantly decreased. Without wishing to be bound by any theory, the inventors believe that the glass transition temperature is initially increased due to the increased crosslinking brought by the alkyne co-monomer compound of formula (I), but too high amounts of this alkyne decrease the glass transition temperature again, as the polymer network is more and more mediated by sulfide bonds, leading to network bond relaxation.

[0069] According to the present application, the polymerizable composition is obtained from polymerizable compounds, such that the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to the prepolymer in the polymerizable composition are adapted such that the molar ratio of SH / alkynyl groups present in all the polymerizable compounds is used in an amount higher than or equal to 7. The molar ratio of SH / alkynyl groups is preferably higher than or equal to 8, 9, 10 or 11, and / or the molar ratio of SH / alkynyl groups is preferably lower than or equal to 90, 85, 81 or 80. Those polymerizable compounds can be compounds of formula (I), polythiols, other classes of optional polymerizable compounds, etc., which can be the same or different.

[0070] According to the present application, the polymerizable composition is obtained from polymerizable compounds, such that the polymerizable compounds used to prepare the prepolymer and the polymerizable compounds added to the prepolymer in the polymerizable composition are adapted such that the molar ratio of NCX / alkynyl groups present in all the polymerizable compounds is used in an amount higher than or equal to 6, X being O or S. The molar ratio of NCX / alkynyl groups is preferably higher than or equal to 7, 8, 9 or 10, and / or the molar ratio of NCX / alkynyl groups is preferably lower than or equal to 90, 85, 80 or 79. Those polymerizable compounds can be compounds of formula (I), poly(iso)thiocyanates, other classes of optional polymerizable compounds, etc., which can be the same or different.

[0071] In one embodiment, when the molar ratio of NCX / alkynyl groups is higher than or equal to 7, 8, 9 or 10, the molar ratio of SH / alkynyl groups is higher than or equal to 8, 9, 10 or 11, respectively. In one embodiment, when the molar ratio of NCX / alkynyl groups is lower than or equal to 90, 85, 80 or 79, the molar ratio of SH / alkynyl groups is lower than or equal to 90, 85, 81 or 80, respectively.

[0072] The molar ratio of reactive groups defined with respect to the polymerizable composition can be calculated from the amounts of all starting materials used to prepare the prepolymer and the polymerizable composition (polythiols, polyiso(thio)cyanates, polymerizable compounds of formula (I), etc.).

[0073] In one embodiment, the prepolymer with thiol end groups obtained by reacting a mixture of at least one polythiol and at least one polymerizable compound having formula (I) is prepared such that the molar ratio of SH / alkynyl groups in the mixture of the polythiol and the polymerizable compound having formula (I) used to prepare the prepolymer is greater than or equal to 7, 8, 9, 10, or 11. The molar ratio of SH / alkynyl groups is preferably less than or equal to 90, 85, 81, or 80.

[0074] In one embodiment, the prepolymer having isocyanate or isothiocyanate end groups of formula -NCX (where X is O or S) obtained by reacting at least one polyisocyanate or polyisothiocyanate with at least one polymerizable compound having formula (I) is such that the molar ratio of the polyisocyanate or polyisothiocyanate used to prepare the prepolymer to the mixture of the polymerizable compound having formula (I) of NCX / alkynyl group is greater than or equal to 6, and X is O or S, more preferably greater than or equal to 7, 8, 9 or 10. The molar ratio of NCX / alkynyl group is preferably less than or equal to 90, 85, 80 or 79.

[0075] In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that, on the one hand, the polymerizable compound used to prepare the prepolymer and on the other hand, the polymerizable compound added to the prepolymer in the polymerizable composition are adapted such that the (NCX group + 2 alkynyl groups) / (SH group + OH, NH2 and / or NHR groups present in all of the polymerizable compounds may be present in compounds having formula (I). 4 The molar ratio of the group is in the range of 0.9 to 1.1, and preferably 1, where X is O or S.

[0076] In fact, when no other functional groups are reactive to these functional groups, the stoichiometric reaction between polyisocyanates, polythiols, and compounds having formula (I) requires three equivalents (OH, SH, NH2, and NHR). 4 (Functional groups) Polymerizable compositions are prepared using two equivalents of alkyne functional groups and one equivalent of NCX functional groups.

[0077] In one embodiment, the polymerizable composition is obtained from polymerizable compounds such that, on the one hand, the polymerizable compound used to prepare the prepolymer and on the other hand, the polymerizable compound added to the prepolymer in the polymerizable composition are adapted to be used in amounts ranging from 0.9 to 1.1 for the (NCX group + alkynyl group) / SH group present in all of the polymerizable compounds, where X is O or S. When this simplified ratio approaches 1, the polymerization reaction is generally close to equilibrium in terms of reactive functional groups.

[0078] In one embodiment, the polymerizable composition is obtained from polymerizable compounds, making that on the one hand the polymerizable compounds used for the preparation of the prepolymer and on the other hand the polymerizable compounds added to said prepolymer in the polymerizable composition are adapted so that the molar ratio of NCX / SH groups present in all said polymerizable compounds is used in an amount ranging from 0.7 to 1.2, more preferably from 0.8 to 1, X being O or S.

[0079] The compound of formula (I) is a heterobifunctional compound containing at least two different reactive (polymerizable) functional groups, i.e. the Z group and the alkynylene-C≡CH group.

[0080] The compound of formula (I) is defined as a compound comprising at least one acetylenic bond. It preferably comprises one or two acetylenic bonds, more preferably one.

[0081] The compound of formula (I) is defined as a compound comprising at least one group selected from OH, SH, NH2or NHR 4 , wherein R 4 represents a substituted or unsubstituted alkyl or (hetero)aryl group. It preferably comprises 1 or 2, more preferably 1 group selected from OH, SH, NH2or NHR 4 , wherein R 4 represents a substituted or unsubstituted alkyl or (hetero)aryl group. The Z and Z' groups of the compound of formula (I) are reactive groups that can participate in a polymerization reaction with an iso(thio)cyanate group.

[0082] In one embodiment, the compound of formula (I) is such that the ratio of groups / alkynyl groups selected from OH, SH, NH2or NHR 4 (R 4 as defined above) per molecule of compound of formula (I) is equal to 1 or 2, preferably 1.

[0083] In the present application, the term "hydrocarbyl" denotes a linear or branched, cyclic or acyclic, saturated or unsaturated hydrocarbon group containing preferably from 1 to 25 carbon atoms, linked to the rest of the molecule via a sp 3 carbon atom, including in particular acyclic groups containing from 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl and n-hexyl, cyclic alkyl groups containing preferably from 3 to 7 carbon atoms, cyclic alkylmethyl groups containing preferably from 4 to 8 carbon atoms.

[0084] A "substituted alkyl" group is understood to mean an alkyl group as defined above in which one or more hydrogen atoms are replaced by a group selected from halogen, hydroxyl, SH, NH2, NHR 3An alkyl group as defined above, in which a carbon atom is attached to the remainder of the molecule and one or more methylene hydrogen atoms are replaced by substituents. The substituted alkyl group may be replaced by one or more aryl groups and / or one or more heteroatoms (such as N, S, O) or halogen atoms (fluorine, chlorine, bromine, or iodine). Arylalkyl groups such as triphenylmethyl (-CPh3), benzyl, or 4-methoxybenzyl, alkoxyalkyl groups, particularly dialkoxymethyl groups such as diethoxymethyl or dimethoxymethyl, and the group CH2CO2R will be mentioned by way of example. 11 , where R 11 Indicates an alkyl or aryl group that may be optionally substituted.

[0085] The term "aryl" refers to a compound containing a single ring (e.g., phenyl) or multiple fused rings (e.g., naphthyl, terphenyl) via sp. 2 The aromatic monovalent carbocyclic group linked to a carbon atom may optionally be substituted with one or more groups, such as, but not limited to, alkyl (e.g., methyl), hydroxyalkyl, aminoalkyl, hydroxyl, thiol, amino, halogen (fluorine, bromine, iodine, chlorine), nitro, alkylthio, alkoxy (e.g., methoxy), aryloxy, monoalkylamino, dialkylamino, acyl, carboxyl, alkoxycarbonyl, aryloxycarbonyl, hydroxysulfonyl, alkoxysulfonyl, aryloxysulfonyl, alkylsulfonyl, alkylsulfinyl, cyano, trifluoromethyl, tetrazolyl, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl. Alternatively, two adjacent positions of the aromatic ring may be substituted with methylenedioxy or ethylenedioxy. The aryl group preferably contains 6 to 15 carbon atoms.

[0086] The term "heteroaryl" indicates that via sp 2 A carbon atom is attached to an aryl group as defined above, which is part of the rest of the molecule, wherein one or more carbon atoms of one or more aromatic rings have been replaced by heteroatoms (such as nitrogen, oxygen, phosphorus, or sulfur). A heteroaryl group can have a structure having one or more aromatic rings, or a structure having one or more aromatic rings coupled to one or more non-aromatic rings. In structures with multiple rings, the rings can be fused, covalently bonded, or bonded together via divalent common groups (such as methylene, ethylene, carbonyl). Examples of heteroaryl groups are thiophene (2-thiophene, 3-thiophene), pyridine (2-pyridyl, 3-pyridyl, 4-pyridyl), isoxazole, phthalimide, pyrazole, indole, furan groups and their benzo-fused analogs, phenylpyridinyl ketones, quinoline, phenothiazine, carbazole, and benzopyranone.

[0087] (Hetero)aryl indicates heteroaryl or aryl.

[0088] The suffix "-ylidene" is used to describe divalent groups. Thus, any monovalent radical defined herein can be modified with the suffix "-ylidene" to describe the divalent form of that moiety. For example, a divalent aryl group is an "arylidene" group, a divalent alkyl group is an "alkylidene" group. Alkylidene groups are connected to the rest of the molecule via two sp 3 Carbon atoms. Arylidene groups are connected to the rest of the molecule via two sp 2 Carbon atoms.

[0089] Examples of alkylidene groups include straight-chain C1-C10 alkylidene groups, such as methylene -CH2-, ethylene -CH2-CH2-, 1,3-propylidene, butylidene or hexylidene, especially 1,4-butylidene and 1,6-hexylidene, and branched-chain C3-C10 alkylidene groups, such as 1,4-(4-methylpentylidene), 1,6-(2,2,4-trimethylhexylidene), 1,5-(5-methylhexylidene), 1,6-(6-methylheptylidene), 1,5-(2,2,5-trimethylhexylidene), 1,7-(3,7-dimethyloctylidene), 2,2-(dimethylpropylidene), 1,5-pentylidene, 1,1-dimethylpentylidene and 1,6-(2,4,4-trimethylhexylidene). Preferred cycloalkylidene groups include cyclopentylidene and cyclohexylidene, which can optionally be substituted especially by alkyl groups.

[0090] Examples of arylidene groups include 2,4-tolylidene, 2,6-tolylidene, 2,4-naphthylidene, 2,6-naphthylidene, 1,5-naphthylidene, 1,4-phenylidene, 1,4-bisphenylidene (-C6H4-p-C6H4-), 2-methyl-1,3-phenylidene, 4-methyl-1,3-phenylidene, tetramethylbenzenedimethylenes, 1,4-phenylidene-methylene-1,4-phenylidene (4,4-biphenylylidene-methylene). p

[0091] In the present application, alkyl groups preferably comprise from 1 to 5 carbon atoms, more preferably from 1 to 4 carbon atoms, from 1 to 3 carbon atoms, or from 1 to 2 carbon atoms.

[0092] In one embodiment, R 1 = R 2 .

[0093] In the present application, the group -R 1 -R 2 preferably represents a straight-chain alkylene group, such as -(CH2)5- (thereby forming a cyclohexyl group with the carbon atom connected to the acetylenic bond) or -(CH2)4-.

[0094] R 1 and R 2 ​The radicals preferably denote, independently of one another, a hydrogen atom or a substituted or unsubstituted alkyl radical, the alkyl radical preferably being a Ci-C5alkyl radical, more preferably a Ci-C2alkyl radical and ideally a methyl radical.

[0095] In a preferred embodiment of the application, R 1 = R 2 = H, or R 1 = R 2 = CH3, or R 1 = H and R 2 = CH3, or R 1 = H and R 2 = 3-heptyl, or R 1 = H and R 2 = = isobutyl.

[0096] One class of useful compounds of formula (I) comprises terminal alkynes, wherein R 3 = H.

[0097] In one embodiment, the polymerizable compound is selected from compounds of formula (IV):

[0098] wherein R 1 and R 2 are as defined above and preferably denote, independently of one another, a hydrogen atom, a substituted or unsubstituted alkyl radical, a (hetero)aryl radical, or R 1 and R 2 together form a divalent radical of formula -R 1 -R 2 -, wherein -R 1 -R 2 - denotes a substituted or unsubstituted alkylene radical, and Z is as defined above and preferably denotes OH, SH or NH2.

[0099] In one embodiment, the polymerizable compound is selected from compounds of formula (II):

[0100] wherein R 1 and R 2 are as defined above and preferably denote, independently of one another, a hydrogen atom, a substituted or unsubstituted alkyl radical, a (hetero)aryl radical, or R 1 and R 2 together form a divalent radical of formula -R 1 -R 2 -, wherein -R 1 -R 2- represents a substituted or unsubstituted alkylene group.

[0101] Particular examples of such compounds of formula (II) are shown below:

[0102] Another class of useful compounds of formula (I) includes those wherein R 3 represent a group of formula:

[0103] wherein R' 1 and R' 2 are as defined above and preferably represent, independently of each other, a hydrogen atom, a substituted or unsubstituted alkyl, (hetero)aryl group, or R' 1 and R' 2 together form a divalent group of formula -R' 1 -R' 2 - wherein -R' 1 -R' 2 - represents a substituted or unsubstituted alkylene group, Z' represents OH, SH, NH2or NHR' 4 wherein R' 4 represents a substituted or unsubstituted alkyl or (hetero)aryl group.

[0104] In one embodiment, R 1 = R 2 and R' 1 = R' 2 In another embodiment, Z = Z'.

[0105] The group -R ’1 -R ’2 - preferably represents a linear alkylene group, such as -(CH2)5- (thus forming a cyclohexyl group with the carbon atom linked to the alkyne bond) or -(CH2)4-.

[0106] R' 1 and R' 2 groups preferably represent, independently of each other, a hydrogen atom or a substituted or unsubstituted alkyl group, the alkyl group preferably being a C1-C5 alkyl group, more preferably a C1-C2 alkyl group and ideally a methyl group.

[0107] In a preferred embodiment of the application, R' 1 = R' 2 = H, or R' 1 = R' 2 = CH3, or R' 1 = H and R' 2 = CH3, or R'1 = H and R' 2 = isobutyl, or R 1 = R 2 = R' 1 = R' 2 = H, or R 1 = R 2 = R' 1 = R' 2 = CH3, or R 1 = R' 1 = H and R 2 = R' 2 = CH3, or R 1 = R' 1 = CH3 and R 2 = R' 2 = isobutyl.

[0108] In one embodiment, the polymerizable compound is selected from compounds having formula (V):

[0109] wherein R 1 , R 2 , R' 1 and R' 2 are as defined above and preferably, independently of one another, represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R 1 and R 2 together form a divalent radical of formula -R 1 -R 2 -, wherein -R 1 -R 2 - represents a substituted or unsubstituted alkylene group, or R' 1 and R' 2 together form a divalent radical of formula -R' 1 -R' 2 -, wherein -R' 1 -R' 2 - represents a substituted or unsubstituted alkylene group, and Z and Z' are as defined above and preferably independently represent OH, SH or NH2.

[0110] In one embodiment, the polymerizable compound is selected from compounds having formula (IIa):

[0111] wherein R 1 , R 2 , R' 1 and R'2 R is as defined above and preferably denotes, independently from each other, a hydrogen atom, a substituted or unsubstituted alkyl, (hetero)aryl group, or R 1 and R 2 form together a bivalent radical of formula -R 1 -R 2 - wherein -R 1 -R 2 - denotes a substituted or unsubstituted alkylene group, or R’ 1 and R’ 2 form together a bivalent radical of formula -R’ 1 -R’ 2 - wherein -R’ 1 -R’ 2 - denotes a substituted or unsubstituted alkylene group.

[0112] Specific examples of such compounds of formula (IIa) are shown hereafter:

[0113] Other examples of useful polymerizable compounds of formula (I) include SH and NH2 analogues of compounds of formula (II) and (IIa), such as propargyl amines or propargyl mercaptans.

[0114] The polymerizable compounds of general formula (I), (II), (IIa), (IV) and (V) are commercially available or can be easily synthesized by chemical reactions well known to the person skilled in the art from widely available and relatively inexpensive starting materials such as propargyl alcohol, propargyl chloride, 1-ethynyl-1-cyclohexanol, 3-butyn-2-ol, 2-methyl-3-butyn-2-ol, 2-butyn-1,4-diol, 3-hexyn-2,5-diol, propargyl mercaptan, propargyl amine, etc. The wide use of these starting materials for the synthesis of the monomers of the present invention makes the cost very competitive in terms of the achieved refractive index.

[0115] The polythiols that can be used in the present invention are defined as compounds comprising at least two sulfhydryl (mercapto) groups, in other words, di-, tri-, tetra-, etc. thiols. Polythiol prepolymers or oligomers can be used. The polythiol can be any suitable polythiol having two or more, preferably two, three or four thiol functional groups.

[0116] Prepolymer means a polymer or oligomer comprising a prepolymer molecule. Prepolymer molecule means a macromolecular or oligomeric molecule capable of entering into further polymerization through reactive (polymerizable) groups, thereby contributing more than one monomeric unit to at least one chain of the final macromolecule. The prepolymer molecule is usually formed from two or more different monomers.

[0117] In one embodiment of the present application, the polythiol is a compound having the formula: R 5 (SH) n1 (III) wherein n1 represents an integer ranging from 2 to 6, and R 5 represents an aliphatic, alicyclic, heterocyclic or aromatic group.

[0118] Suitable preferred polythiol monomers and / or oligomers according to the present application can be listed among the aliphatic polythiols such as trimethylolpropane tri(2- mercaptoacetate), trimethylolpropane tri(3-mercaptopropionate), trimethylolethane tri(2- mercaptoacetate), trimethylolethane tri(3-mercaptopropionate), pentaerythritol tetra(2- mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), dipentaerythritol hexa(3- mercaptopropionate), bis(mercaptomethyl)sulfide, bis(mercaptomethyl)disulfide, bis(mercaptoethyl)sulfide, bis(mercaptoethyl)disulfide, bis(mercaptopropyl)sulfide, bis(mercaptopropyl)disulfide, 2,3-bis((2-mercaptoethyl)thio)-1-propane thiol of formula (Via), 4,8- dimercaptomethyl-1,1 1 -dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,1 1 - dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,1 1 -dimercapto-3,6,9- trithiaundecane, 2,5-bis(mercaptomethyl)-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'-mercaptpentylthio)-2,3-dimercaptopropane, 1 -(6'-mercaptohexylthio)-2,3-dimercaptopropane, 1,2-bis-(4'-mercaptobutylthio)-3- mercaptopropane, 1,2-bis-(5'-mercaptpentylthio)-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-hexanedithiol-1,2,3-propanethiol, 1,2-bis(2'-mercaptoethylthio)-3- mercaptopropane, tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate of formula (Villa), 2- mercaptoacetate 2-mercaptoethyl ester, 3-mercaptopropionate 2-mercaptoethyl ester of formula (IX), 1,1,3,3-tetrakis(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3- dithiane, 1,1,2,2-tetrakis(mercaptomethylthio)ethane, 3-mercaptomethyl-1,5-dimercapto-2,4-dithiolane, tris(mercaptomethylthio)methane, ethylene glycol bis(3- mercaptopyrrolate), butanediol bis(3-mercaptopyrrolate), 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithiane.

[0119] (X) (VIIIa) (X) Further examples of polythiols are shown in the following formulae or can be found in WO 2014 / 133111, EP 394495, US 4775733 or EP 1877839:

[0120] In one embodiment of the present application, the polythiol is selected from the group consisting of pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(2- mercaptoacetate), tris(3-mercaptopropionate)trimethylolpropane, tris(2- mercaptoacetate)trimethylolpropane, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol, ethylene glycol bis(3-mercaptopropionate), butanediol bis(3-mercaptopropionate), 2- mercaptoacetic acid 2-mercaptoethyl ester, 3-mercaptopropionic acid 2-mercaptoethyl ester, 5,7-dimercaptomethyl-1,1 1-dimercapto-3,6,9-trithiaundecane, 4,7- dimercaptomethyl-1,1 1-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,1 1- dimercapto-3,6,9-trithiaundecane, 2,5-bis(mercaptomethyl)-1,4-dithiane, bis(mercaptoethyl) sulfide, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3- dithiane, 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithietane, 1,1,2,2-tetrakis(mercaptomethylthio)ethane, 3-mercaptomethyl-1,5-dimercapto-2,4- dithiolane, tris(mercaptomethylthio)methane, dipentaerythritol hexa(3- mercaptopropionate), tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, and ethanedithiol.

[0121] The most preferred polythiols are 2-mercaptoacetic acid 2-mercaptoethyl ester having formula (IX), pentaerythritol tetra(3-mercaptopropionate) having formula (X) and 2,3- bis((2-mercaptoethyl)thio)-1-propanethiol having formula (Via). In particular, a mixture of 2-mercaptoacetic acid 2-mercaptoethyl ester and 2,3-bis((2- mercaptoethyl)thio)-1-propanethiol can be used.

[0122] In one embodiment, a mixture of at least two different polythiols, preferably having a different number of thiol groups, is used, for example a mixture of two polythiols. In some embodiments, the polymerizable composition comprises at least one polythiol having three SH groups and at least one polythiol having four SH groups. In one embodiment, the polymerizable composition comprises a mixture of pentaerythritol tetra(3-mercaptopropionate) and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol.

[0123] By adjusting the respective proportions of the polythiols, the refractive index and the mechanical properties of the final polymer can be adjusted.

[0124] Polyisocyanate means any compound comprising at least two isocyanate groups, in other words diisocyanates, triisocyanates, etc. Polyisocyanate prepolymers can be used. The polyisocyanate can be any suitable polyisocyanate having two or more, preferably two or three isocyanate functional groups.

[0125] The polyisocyanate can be chosen from aliphatic, aromatic, cycloaliphatic or heterocyclic polyisocyanates and mixtures thereof.

[0126] The polyisothiocyanate is defined in the same way as the polyisocyanate described above, by replacing the “isocyanate” group with an “isothiocyanate” group.

[0127] In one embodiment of the application, the polyisocyanate or polyisothiocyanate is a compound of formula (VI): R 6 (NCX) n2 (VI) where X represents O or S, n2 represents an integer ranging from 2 to 6, and R 6 represents an aliphatic, cycloaliphatic, heterocyclic or aromatic radical.

[0128] The preferred polyisocyanate or polyisothiocyanate compounds are those of formula:

[0129] where R 1 is independently H or C1-C5 alkyl, preferably CH3 or C2H5; R 2 is H, halogen, preferably Cl or Br, or C1-C5 alkyl, 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; and x is an integer from 1 to 10, preferably 1 to 6.

[0130] The polyisocyanate of the present application is preferably a diisocyanate, such as an arylene diisocyanate. Among the diisocyanates that can be used, mention can be made of tolylene-2,4-diisocyanate, tolylene-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, norbornane diisocyanate, ethylene diisocyanate, dodecane-1,12-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene-2,4-diisocyanate, tetramethylxylylene diisocyanate, hexahydrotoluene-2,6-diisocyanate, perhydrodiphenylmethane-2,4'-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, 2,5-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, 1,5-naphthalene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate trimer, 1,6-hexamethylene diisocyanate trimer, and mixtures thereof.

[0131] Further polyis(thio)cyanates suitable for the present application are described in detail in WO 98 / 37115, WO 2014 / 133111 or EP 1877839.

[0132] Preferred embodiments are the combination of xylylene diisocyanate and pentaerythritol tetrakis(3-mercaptopropionate); the combination of xylylene diisocyanate and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol; the combination of 2,5 (or 2,6)-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, pentaerythritol tetrakis(3-mercaptopropionate) and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol; the combination of xylylene diisocyanate and 4,8 (or 4,7 or 5,7)-dimercaptomethyl-1,1 1-dimercapto-3,6,9-trithiaundecane; the combination of dicyclohexylmethane diisocyanate and 4,8 (or 4,7 or 5,7)-dimercaptomethyl-1,1 1-dimercapto-3,6,9-trithiaundecane.

[0133] The polymerizable compositions according to the invention may also contain additives, in conventional proportions, commonly used in polymerizable compositions intended for use in molding optical articles, particularly ophthalmic lenses, namely catalysts / polymerization initiators, photochromic agents, UV absorbers, fragrances, deodorants, resin modifiers, color balancers, chain extenders, crosslinking agents, free radical scavengers such as antioxidants or hindered amine light stabilizers (HALS), dyes, pigments, fillers, adhesion promoters, inhibitors, anti-yellowing agents, and release agents.

[0134] UV absorbers are often incorporated into optical materials to reduce or prevent UV light from reaching the retina (especially in ophthalmic lens materials). UV absorbers used in this invention preferably have the ability to at least partially block light with wavelengths shorter than 400 nm, but may also have an absorption spectrum extending into the visible blue light range (400-450 nm), particularly 420-450 nm.

[0135] The UV absorber protects the user's eyes from UV light and also protects the optical materials themselves, preventing them from weathering, becoming brittle, and / or yellowing. The UV absorber according to the 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)-benzotriazoles such as 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (Seesorb). ® 703 / Tinuvin ® 326), or other allyl hydroxymethyl phenyl chlorobenzotriazole, 2-(5-chloro-2H-benzotriazole-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 Tinuvin from BASF. ® CarboProtect ® Preferred absorbers are from the benzotriazole family. Other examples of benzotriazole UV absorbers that protect against blue light can be found in WO 2017 / 137372.

[0136] The amount of UV absorber compound according to the application used herein is an amount sufficient to provide satisfactory protection from UV light, but not so much as to prevent precipitation. The UV absorber compound of the present application 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 polymerizable compound present in the composition or relative to the weight of the optical material composition).

[0137] Among the release agents that can be used in the present application, mention can be made of mono- and dialkyl phosphates, alkyl phosphate esters, silicones, fluorinated hydrocarbons, fatty acids and ammonium salts. The preferred release agents are mono- and dialkyl phosphates, alkyl phosphate esters and mixtures thereof. Such release agents are notably disclosed in US 4975328 and EP 271839. The release agent is preferably used in an amount lower than or equal to 1% by weight, based on the total weight of the polymerizable compounds present in the polymerizable composition (or relative to the weight of the optical material composition).

[0138] The optical material is a dual-cure system, in the sense that it is obtained from both a thermally polymerizable and a photopolymerizable compound.

[0139] In one embodiment, the optical material polymerizable composition contains (or is prepared using) at least one system for initiating and / or accelerating the polymerization reaction (initiator). The polymerization initiation system can comprise at least one (thermal) catalyst or at least one photochemical polymerization initiator (photoinitiator) or alternatively a mixture of (thermal) and photochemical polymerization initiators. In a preferred embodiment, the polymerizable composition contains both a photoinitiator and a (thermal) catalyst (or is prepared using both a photoinitiator and a (thermal) catalyst).

[0140] The polymerization initiation system can be used to initiate and / or accelerate the polymerization reaction of the prepolymer having a thiol end group or of the prepolymer having an isocyanate or isothiocyanate end group of formula -NCX (where X is O or S, the prepolymer being obtained from at least one polymerizable compound of formula (I) and at least one polythiol or at least one polyisocyanate or polyisothiocyanate), and can still be present in the polymerizable composition comprising the prepolymer and the complementary polymerizable compound.

[0141] The polymerization initiation system can also be used in the polymerizable composition to initiate and / or accelerate the polymerization reaction between the prepolymer and the complementary polymerizable compound.

[0142] A photoinitiator denotes a molecule that absorbs light and generates a reactive species (ion or radical) that initiates a chemical reaction or transformation. In the present application, the photoinitiator is preferably used to promote the reaction between a thiol group and an alkyne group (thiol-alkyne reaction).

[0143] Photoinitiators can be selected from, for example, halogenated alkylated aromatic ketones such as chloromethylbenzophenone, benzoin and benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin, dialkoxyacetophenones such as diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone, benzyl acetophenone, hydroxy ketones such as (1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-prop-1-one) (from Ciba Corporation's Irgacure). ® 2959), 2,2-di-sec-butoxyacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1-hydroxy-cyclohexyl-phenyl-ketone (from Ciba's Irgacure) ® 184) and 2-hydroxy-2-methyl-1-phenylprop-1-one (such as Darocur sold by Ciba) ® 1173), α-amino ketones, especially those containing a benzoyl moiety, are also known as α-aminoacetophenones, such as 2-methyl-1-[4-phenyl]-2-morpholinopropyl-1-one (from Ciba's Irgacure). ® 907), (2-phenyl-2-dimethylamino-1-(4-morpholinophenyl)-but-1-one (from Ciba's Irgacure) ® 369), monoacyl and diacylphosphine oxides and sulfides, such as phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide (Irgacure sold by Ciba). ® 819 and Irgacure ® 2022, which contains Irgacure ® 819 and Darocur ® Blends of 1173), 2,4,6,-trimethylbenzoylethoxydiphenylphosphine oxide, triacylphosphine oxide, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole and mixtures thereof.

[0144] Thermally or photocatalyzed free radical initiators, such as peroxides and azo compounds, as well as Lewis acids, such as triarylsulfonium hexafluoroantimonate or diaryliodonium salts, can also be used.

[0145] The photoinitiator should be used in the polymerizable composition or for the preparation of the prepolymer according to the application in an amount sufficient to promote the polymerization reaction. They are generally present in an amount ranging from 0.05% to 10% by weight, preferably from 0.2% to 5% by weight, and more preferentially from 0.25% to 2% by weight, relative to the total weight of the polymerizable compounds present in the polymerizable composition or used for the preparation of the prepolymer according to the application, or relative to the total weight of the polymerizable compounds used for the preparation of the prepolymer and of the polymerizable compounds added to said prepolymer in the polymerizable composition.

[0146] In the present application, the thermal catalyst promotes the reaction (thiourethanization reaction) between the is(thio)cyanate group and a functional group selected from thiol, hydroxyl, amino and NHR 4 4 represents a group of substituted or unsubstituted alkyl or (hetero)aryl) between the is(thio)cyanate group and a functional group selected from thiol, hydroxyl, amino and NHR 4 4 The heating favors this condensation reaction.

[0147] In one embodiment, the (thermal) catalyst is selected from tin compounds such as alkyl tin, alkyl tin oxides, metal complexing complexes such as cobalt naphthenate and amine or nitrogen-containing basic compounds. Several catalysts can be combined in the polymerizable composition of the application.

[0148] The tin catalyst can be selected from the group consisting of tin octoate, tin octoate (tin 2-ethylhexanoate), dibutyl tin diacetate, dibutyl tin dichloride, dimethyl tin dichloride, dibutyl tin dilaurate, dibutyl tin mercaptide, dibutyl tin dimaleate, dimethyl tin diacetate, dimethyl tin dilaurate, dimethyl tin mercaptide, dimethyl tin dimaleate, triphenyl tin acetate, triphenyl tin hydroxide.

[0149] The amine or nitrogen-containing basic catalyst can be selected from aliphatic or aromatic tertiary amines, which preferably contain a supplementary heteroatom in the ring or a functional group with a positive inductive and / or a positive mesomeric effect (e.g. alkyl or amino groups). Examples include 1,4-diazabicyclo[2.2.2]octane (DABCO), triethylamine, quinuclidine, 2,2'-dimorpholino diethyl ether, N,N-dimethylpiperazine, 1-methylimidazole, 2-methyl-1-vinylimidazole, 1-allylimidazole, 1-phenylimidazole, 1,2,4,5-tetramethylimidazole, 1(3-aminopropyl)imidazole, 4-dimethylaminopyridine, 4-pyrrolidinyl-pyridine, 4-morpholinopyridine, 4-methylpyridine, 3,5-dimethylpyridine, N-dodecyl-2-methylimidazole, triazines such as tris(dimethylaminopropyl)hexahydrotriazine, dimethylbenzylamine, N,N-dimethylcyclohexylamine, bis-dimethylamino-ethyl ether and pentamethyldiethylene triamine.

[0150] In another embodiment, the catalyst is of formula salt compounds, wherein M p+ is a cation having a valence p selected from the group consisting of alkali metal cations, alkaline earth metal cations, transition metal cations and ammonium groups of the formula NR4 + , wherein R is an alkyl group, preferably having from 1 to 10 carbon atoms, Y - is an anion, such that the corresponding acid YH has a pKa satisfying the condition 0.5 ≤ pKa ≤ 14, m, n and p are integers such that n = m x p.

[0151] Preferred metal cations of the salt are Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Mn 2+ , Ag + , Ba 2+ and Al 3+ . Particularly preferred metal cations are Li + , Na + and K + , as they are not present in color and solubility in the composition. Transition metals are less preferred as their salts can lead to colored compositions and thus to colored polymeric resins. In one embodiment, the process according to the present application does not use a catalyst containing tin.

[0152] Preferred NR + 4 groups are those wherein R is a Ci-C8alkyl group and more preferably methyl, ethyl, propyl, butyl or hexyl.

[0153] Preferably, Y - is an anion, such that the corresponding acid YH satisfies the condition 0.5 ≤ pKa ≤ 10, and more preferably 0.5 ≤ pKa ≤ 8. In the present application, pKa is preferably expressed at 25°C. The pKa can be measured in water at standard pressure using a glass electrode and a pH meter by potentiometric (pH) titration.

[0154] Preferably, the anion Y - is selected from the group consisting of thiocyanate, carboxylate anions, thiocarboxylate anions, acetylacetonate, diketonate anions, acetoacetate anions, malonate anions, cyanoacetate anions, ketonitrile anions, malonitrile anions and anions of the formula RS - , wherein R is a substituted or unsubstituted alkyl group, preferably having from 1 to 10 carbon atoms, or an aryl group, preferably having from 6 to 12 carbon atoms.

[0155] Preferred anions Y- is SCN - , acetylacetonate, acetate, thioacetate, formate and benzoate. The preferred salt catalyst is potassium thiocyanate KSCN.

[0156] Such salt catalysts are described in more detail in application US 2007 / 202265. They are preferably used in combination with an electron donor compound (such as a crown ether, typically 18-crown-6) also described in US 2007 / 202265.

[0157] The (thermal) catalysts should be used in the polymerizable composition or in the preparation of the prepolymer according to the application in an amount sufficient to promote the polymerization of the mixture. They are generally present in an amount ranging from 0.01 % to 5% by weight, more preferentially from 0.02% to 2% by weight, relative to the total weight of polymerizable compounds present in the polymerizable composition or used in the preparation of the prepolymer according to the application, or relative to the total weight of polymerizable compounds used in the preparation of the prepolymer and of the polymerizable compounds added to said prepolymer in the polymerizable composition. Too high amounts of catalyst should also be avoided to prevent premature gelling of the polymerizable mixture before it is introduced into the mold.

[0158] The polymerizable composition can comprise a solvent for promoting the dissolution of the additives (such as catalysts). Any polar organic solvent can be used, such as acetonitrile, tetrahydrofuran, dioxane, ethanol, 2-mercaptoethanol, acetone or 3-methyl-2-buten-1-ol. The amount of solvent is generally kept below 2% by weight, and preferably from 0% to 0.5% by weight, based on the total weight of polymerizable compounds present in the composition, to avoid turbidity and bubbling.

[0159] The present application also relates to an optical material obtained by polymerization of a polymerizable composition as described above. The optical material combines thioether and thiocarbamate functional groups, and optionally carbamate (when Z or Z' = OH) and / or urea (when Z or Z' = NH2or NHR 4 as defined above) functional groups, depending on the structure of the compound of formula (I). The thioether bond results from the reaction of an alkynyl group with a thiol, the thiocarbamate bond results from the reaction of an iso(thio)cyanate group with a thiol, the carbamate bond results from the reaction of an iso(thio)cyanate group with an alcohol, and the urea bond results from the reaction of an iso(thio)cyanate group with an amine.

[0160] The optical material according to the present application is distinguishable from the related polythiourethane-based optical materials obtained in the prior art by means of its improved thermo-mechanical properties (impact resistance, elastic modulus, glass transition temperature...) and lower yellowness index (as demonstrated in the experimental part), and also its improved monomer conversion.

[0161] The conversion rate of the polyisocyanate or polyisothiocyanate compound in the optical material according to the application is preferably higher than or equal to 95%, more preferably higher than or equal to 98%. The conversion rate of such a compound can be calculated by methods well known to the skilled person, such as by infrared spectroscopy studying the relative intensity of the NCO / NCS peak on the solid lens relative to the relative intensity of the NCO / NCS peak on the monomer.

[0162] As an example, reference will be made to Figure 1 and Figure 2 The calculation of the relative intensity of the NCO / CH peak on the solid lens relative to the relative intensity of the NCO / CH peak on the monomer by infrared spectroscopy is detailed in the experimental part.

[0163] The calculation of the NCO conversion rate (or conversion rate) is described hereafter.

[0164] The conversion rate is related to the completion of the polymerization, which is calculated by comparing the relative NCO value of the lens to the relative NCO value of the monomer.

[0165] PkNCO and PkCH2 are measured on the FTIR spectrum of the initial monomer composition (comprising one or more isocyanate and one or more thiol) after the corresponding reaction time, as shown on the typical spectrum of Figure 1 and on the FTIR spectrum of the corresponding polymer composition, as shown on the typical spectrum of Figure 2

[0166] Pk is the peak intensity corresponding to the T at the baseline of the NCO peak or CH2 peak.

[0167] The ratio of NCO to CH2 internal peak can then be calculated according to the following equation:

[0168] The NCO residual rate and conversion rate are then calculated according to the following equations:

[0169] The application further relates to a prepolymer having thiol end groups, obtained from the reaction of a mixture of at least one polythiol and at least one polymerizable compound having formula (I) as described above, wherein the molar ratio of SH / alkynyl of the mixture of polythiol and polymerizable compound having formula (I) used to prepare said prepolymer is higher than or equal to 7. The preferred SH / alkynyl molar ratios described above also apply to this prepolymer.

[0170] ​The application further relates to a prepolymer having an isocyanate or isothiocyanate end group of formula -NCX, wherein X is O or S, which is obtained from the reaction of a mixture of at least one polyisocyanate or polyisothiocyanate and at least one polymerizable compound of formula (I) as described above, wherein the molar ratio of NCX / alkynyl of the mixture of polyisocyanate or polyisothiocyanate used for the preparation of said prepolymer and of the polymerizable compound of formula (I) is higher than or equal to 6. The preferred molar ratio of NCX / alkynyl described above also applies to this prepolymer.

[0171] The application further relates to a process for the preparation of an optical material as described above, which comprises the following steps 1), 2) and 3) or 1'), 2') and 3'): 1) providing a first component comprising at least one prepolymer having a thiol end group, which is obtained by polymerization, preferably photopolymerization, of a mixture of at least one polythiol and at least one polymerizable compound of formula (I) as described above in the presence of at least one initiator, preferably a photoinitiator, 2) providing a second component comprising at least one polyisocyanate or polyisothiocyanate, 3) mixing the first component and the second component together to form a polymerizable composition and thermally polymerizing said polymerizable composition in the presence of at least one catalyst to obtain an optical material, or: 1') providing a first component comprising at least one prepolymer having an isocyanate or isothiocyanate end group of formula -NCX, wherein X is O or S, which is obtained by thermal polymerization of a mixture of at least one polyisocyanate or polyisothiocyanate and at least one polymerizable compound of formula (I) as described above in the presence of at least one catalyst, 2') providing a second component comprising at least one polythiol, 3') mixing the first component and the second component together to form a polymerizable composition and polymerizing, preferably photopolymerizing, said polymerizable composition in the presence of at least one initiator, preferably a photoinitiator, to obtain an optical material, wherein the polymerizable composition is obtained from polymerizable compounds, such that on the one hand the polymerizable compounds used for the preparation of the prepolymer and on the other hand the polymerizable compounds mixed with said prepolymer in the polymerizable composition are adapted in such a way that the molar ratio of SH / alkynyl present in all said polymerizable compounds is higher than or equal to 7, and The polymerizable composition is obtained from polymerizable compounds, such that the polymerizable compounds used for the preparation of the prepolymer on the one hand and the polymerizable compounds mixed with said prepolymer in the polymerizable composition on the other hand are adapted such that the molar ratio of NCX / alkynyl present in all said polymerizable compounds is used in an amount higher than or equal to 6, X being O or S.

[0172] Compared to prior art processes using only is(thio)cyanate, alkyne or thiol monomers, the present invention uses at least one prepolymer, which offers several advantages. As demonstrated in the experimental part, the optical material obtained by the process of the present invention starting from a prepolymer and a complementary polymerizable compound has a much lower yellowness index than the corresponding optical material obtained by in situ mixing of the same amount of all precursor monomers.

[0173] The process preferably involves cast polymerization.

[0174] The mixing of the different components of the polymerizable composition can be performed by any known mixing technique, such as those mentioned in US 5973098, preferably by introducing the components into a small reactor chamber and then mixing with a screw mixer.

[0175] In one embodiment, one or more of the above-mentioned additives, such as an initiator, are added to the first component (comprising the prepolymer) before mixing with the second component (comprising the complementary polymerizable compound). In another embodiment, one or more of the above-mentioned additives are added to the mixture of polymerizable compounds of formula (I) with a polythiol or a polyisocyanate or a polyisothiocyanate, i.e. during the preparation of the prepolymer (component A or B). In another embodiment, one or more of the above-mentioned additives are added during or before step 3) or 3") in which the first and second components are mixed together.

[0176] The optical material is obtained by a sequential process, in which first a prepolymer is formed from a compound of formula (I) and then reacted with a complementary polymerizable compound, which is a polythiol or a poly(iso)thiocyanate, depending on the end group of the prepolymer.

[0177] The mold cavity of a mold assembly having any desired shape can then be filled with the polymerizable composition.

[0178] A mold assembly typically comprises two mold pieces defining two molding surfaces that cooperate to form a mold cavity when moved from an open position to a closed position. Each of the molding surfaces can be concave, convex, or planar, depending on the desired article shape. The molding surfaces can be convex, for example to form a concave substrate surface, or concave, for example to form a convex substrate surface.

[0179] More specifically, the optical material composition can be injected into the cavity of two mold parts held together using a ring-shaped closure, such as a gasket or a tape.

[0180] The ring-shaped closure member can be provided around the periphery of the two mold pieces and attached to them. The conventional way of filling such a two-piece mold is by flowing the (liquid) optical material composition into the mold cavity through a casting opening provided in the closure member for this purpose. In an at least partially automated process, the mold cavity to be filled is vertically aligned with a filling device which is adapted to deliver a specific amount of molding material through a nozzle.

[0181] Depending on the desired features of the resulting optical material, degassing under reduced pressure and / or filtering under increased or reduced pressure can be performed prior to injecting the optical material composition into the mold assembly.

[0182] After the composition is cast in the mold assembly, preferably the lens mold assembly, polymerization is triggered.

[0183] The thiol-yne reaction occurs upon irradiation. This is the main reaction that occurs during step 3’) of the method of the present invention. The thiocarbamate formation reaction (and possible urea and / or carbamate bond formation) occurs upon heating. This is the main reaction that occurs during step 3) of the method of the present invention.

[0184] The thiol / alcohol / amine-is(thio)cyanate condensation on the one hand and the thiol-yne condensation on the other hand can be performed orthogonally, especially when a combination of a thermal catalyst and a photoinitiator is used to polymerize the polymerizable composition.

[0185] The photopolymerization of the polymerizable composition (formation of the pre-polymer or optical material) can be performed by irradiating the composition with radiation, preferably ultraviolet light. Preferably, the UV light wavelength ranges from 320 nm to 390 nm. The UV light intensity typically ranges from 40 to 90 mW / cm 2 and the total exposure time to UV light, whether in one shot or multiple shots, is preferably in the range from 15 to 1650 seconds, more preferably from 20 to 600 seconds.

[0186] The thermal polymerization of the polymerizable composition (formation of the pre-polymer or optical material) can be performed in an oven or a heating device immersed in water according to a predetermined temperature program to cure the resin. Thermal polymerization includes induction and infrared heating. The curing temperature typically ranges from 60 °C to 140 °C. The curing time is preferably lower than or equal to 25, 20, 10 or 5 hours, more preferably lower than or equal to 4, 3 or 2 hours. As used herein, curing refers to the chemical process of converting monomers or oligomers into polymers of higher molar mass and then into a network.

[0187] If desired, the resin molded product can then be annealed at a temperature preferably ranging from 100°C to 150°C.

[0188] Thereafter, the mold assembly is removed from the heat source, the annular closure is removed, and the polymerized optical material can be obtained after disassembling the mold parts.

[0189] The method of the application can be used to manufacture finished lenses, both faces of which are of the desired geometry, or semi-finished lenses, one face of which still needs to be surface treated in the desired geometry.

[0190] In some applications, it is preferred that the main surfaces of the optical material are coated with one or more functional coatings to improve optical and / or mechanical properties. The term "coating" is understood to mean any layer, layer stack or film that can be in contact with the substrate and / or with another coating, for example a sol-gel coating or a coating made of an organic resin. The coatings can be deposited or formed by various methods, including wet processing, gas processing and film transfer. These functional coatings, which are classically used in optics, can be, without limitation, impact-resistant and / or adhesion primers, abrasion- and / or scratch-resistant coatings, anti-reflective coatings, polarizing coatings, photochromic coatings, or antistatic coatings, or stacks made of two or more such coatings, in particular impact-resistant primer coatings coated with abrasion- and / or scratch-resistant coatings.

[0191] The following examples illustrate the application in more detail but in a non-limiting manner. Unless otherwise stated, all thicknesses disclosed in this application relate to physical thicknesses. The percentages given in the tables are percentages by weight.

[0192] Examples

[0193] The polymerizable heterobifunctional alkyne compound according to the application can be chosen from, but is not limited to, the compounds of formula:

[0194] 1. Chemicals used and polymerization conditions

[0195] The optical substrate was prepared by polymerization of a heterobifunctional alkyne monomer (propargyl alcohol, CAS number 107-19-7), at least one polythiol monomer and a polyisocyanate monomer (isophorone diisocyanate, CAS number 4098-71-9) in the presence of a photoinitiator (2,2-dimethoxy-2-phenylacetophenone, CAS number 24650-42-8, 0.25% by weight) and a thermal catalyst (dimethyltin dichloride, CAS number 753-73-1, 0.2% by weight). The polymerizable composition also contained Zelec UN ®As a release agent (0.15% by weight).

[0196] The following polythiol monomers were used: 2,3-bis((2-mercaptoethyl)thio)-1- propanethiol (CAS number 131538-00-6) and / or pentaerythritol tetrakis(3- mercaptobutyrate) (CAS number 7575-23-7).

[0197] Clean convex and concave plano glass molds with a high refractive index of 75 mm diameter were assembled with adhesive tape. Center thickness adjustment was performed to obtain 1.1 mm thick samples. The thermal catalyst, the photoinitiator and the alkyne monomer of formula (I) were dissolved in one or more polythiol monomers in a Duran bottle with magnetic stirrer at room temperature for 30 minutes. The prepolymerization reaction was performed by UV-irradiation (365 nm) for 30 seconds (Examples 1 to 4, C1 to C3) or 180 seconds (Examples 5 to 7, C4) in a UV-LED curing oven (Height-LED HTBX-II). The thermal catalyst was added in this initial stage to make it easier to dissolve.

[0198] The resulting prepolymer with thiol end groups was mixed with the polyisocyanate monomer and the release agent. The composition was allowed to degas for 10-30 minutes to avoid bubbles in the final material.

[0199] The assembled mold was filled with the polymerizable composition prepared above using a clean syringe and the polymerization was performed by thermal curing (100 °C, 2 h, 120 °C, 10 h for all examples except Examples C4, 5-7) by placing the assembled mold in a convection oven (hot air oven, model B: 121218B, Reliance tech-service Co, LTD) to complete the polymerization.

[0200] The mold was removed from the oven and allowed to cool at room temperature for 10 minutes and then disassembled when the surface temperature of the mold was < 50 °C to obtain a lens comprising a thermoset material body.

[0201] In Comparative Example 1 (denoted as C1), no alkyne monomer was used. Isophorone diisocyanate is difunctional and pentaerythritol tetrakis(3- mercaptobutyrate) is tetrafunctional, the NCO / SH molar ratio used of 1 : 1 indicates the use of 0.5 mol of the latter for 1 mol of the former (see 3).

[0202] 2. Test methods

[0203] The following test procedures were used to evaluate the optical articles prepared according to the application. They were obtained from an integration of 5 different casting runs.

[0204] The thermal and mechanical properties (glass transition temperature Tg and elastic modulus E) of the lenses have been evaluated by DMA (Dynamic Mechanical Analysis) using a Dynamic Mechanical Analyzer Q800 module supplied by TA Instruments. The measurements were performed in a multi-frequency strain mode. The samples were in the shape of a rectangle with dimensions 50 x 8 x 2 mm. The operation was performed from 25°C-130°C at a heating rate of 2°C / min, at 30 pm amplitude, pre-load force 0.5 N, force tracking 150%.

[0205] The impact resistance of a 75 mm diameter plano lens (center thickness: 1.1 mm) was evaluated according to the FDA Ophthalmic Eye Wear Drop Ball Test (ANSI Z87.1-1989 standard). This test consists in dropping a 16 g steel ball from a height of 127 cm onto the center of the convex face of the lens, which corresponds to an energy of 200 mJ. The lens successfully passed the test when it did not break nor present star cracks. The impact test was performed on at least four independent casting runs to ensure reproducibility.

[0206] The yellowness index Yi of the optical materials prepared was calculated by reflectance measurements by measuring the CIE tristimulus values X, Y, Z as described in the standard ASTM E 313-05 on a white background with a Cary 60 spectrophotometer, with the front (convex) side of the lens facing the detector and the light entering on said front side. From the observer’s point of view, this way of measuring Yi is the closest to the real wearing situation.

[0207] 3. Prepared optical articles and characterization

[0208] The following table indicates the different monomer formulations prepared as well as the thermal mechanical properties of the resulting polymers. NCO / SH, NCO / alkyne and SH / alkyne are the molar ratios of the reactive functions introduced to prepare the prepolymer and polymerizable composition. Polyisocyanate / alkyne compound (I) and polythiol / alkyne compound (I) are the molar ratios of the monomers introduced to prepare the prepolymer and polymerizable composition. The SH function is used in an amount equilibrating the amount of NCO + alkyne functions.

[0209] a) Results with the polythiol pentaerythritol tetra(3-mercaptopropionate)

[0210] The optical material according to the present application successfully passed the FDA impact resistance test at amounts of alkyne component as low as 0.3% by weight, while maintaining very good optical quality, such as low or no visual haze. In comparison, the optical material of Comparative Example 1 (containing no alkyne monomer) did not pass the impact resistance test.

[0211] The presence of the alkyne component improved or maintained the glass transition temperature of the resulting polymer at high levels (89°C - 94°C) compared to Comparative Example 1 (92°C). However, when the amount of alkyne modifier was too high (Comparative Examples 2 and 3), the glass transition temperature of the resulting polymer decreased significantly (70°C - 79°C).

[0212] The introduction of the alkyne compound of Formula (I) into the polythiurethane matrix also improved the elastic modulus of the resulting polymer compared to the pure polythiurethane matrix of Comparative Example 1.

[0213] b) Results with a mixture of polythiols: 2,3-bis((2-mercaptoethyl)thio)-1- propanethiol (polythiol 1) and pentaerythritol tetra(3-mercaptopropionate) (polythiol 2)

[0214] Similar trends were observed regarding the effect of alkyne addition on the thermo-mechanical properties (modulus improvement) in Examples 5-7 on the one hand and Examples 1-4 on the other hand.

[0215] 4. Comparison of the polymerization process using a prepolymer with the polymerization process starting from monomers Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Examples Chemicals used and polymerization conditions Test methods Prepared optical articles and characterization a) Results with the polythiol pentaerythritol tetra(3-mercaptopropionate) b) Results with a mixture of polythiols: 2,3-bis((2-mercaptoethyl)thio)-1- propanethiol (polythiol 1) and pentaerythritol tetra(3-mercaptopropionate) (polythiol 2) Comparison of the polymerization process using a prepolymer with the polymerization process starting from monomers

[0216] Further experiments were performed by changing the polymerization method to show the benefit of forming the optical material from the reaction of a prepolymer with a polyisocyanate monomer instead of from the reaction of three monomers on the yellowness index.

[0217] The optical material was prepared by one-pot reaction of three monomers (polyisocyanate, polythiol, alkyne compound of Formula (I)) using the same amounts of monomers as in Comparative Examples 1-3 and Examples 1-4.

[0218] The one-pot preparation method was as follows. In a Duran flask with magnetic stirrer, the polyisocyanate monomer and the alkyne monomer of Formula (I) were mixed with thermal catalyst, photoinitiator and mold release agent. The solution was homogenized by stirring for 5 minutes. Thereafter, the reaction was cooled at 20°C - 22°C and the polythiol monomer was added. The composition was then mixed and allowed to degas for 30 minutes to avoid bubbles in the final material. The degassing was continued for 5 minutes without stirring. The assembled mold was filled with the polymerizable composition prepared above using a clean syringe and the polymerization reaction was carried out by UV-irradiation and then by thermal curing under the same conditions as in Comparative Examples 1-3 and Examples 1-4.

[0219] The following shows that the optical material obtained by the method of the present application starting from a prepolymer and a complementary polymerizable compound has a much lower yellowness index than the corresponding optical material obtained by mixing all the precursor monomers in situ.

[0220] .

Claims

1. A polymerizable composition comprising: a) At least one polyisocyanate or polyisothiocyanate and component B comprising at least one prepolymer having a thiol end group, said component B being obtained by reacting at least one polythiol with a mixture of at least one polymerizable compound having formula (I), or b) Component A of at least one polythiol and a prepolymer comprising at least one isocyanate or isothiocyanate end group having the formula -NCX, wherein X is O or S, said component A being obtained by reacting at least one polyisocyanate or polyisothiocyanate with a mixture of at least one polymerizable compound having formula (I), Where R 1 and R 2 Each of these can independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R. 1 and R 2 Together they form a form with -R 1 -R 2 - a divalent group, wherein -R 1 -R 2 - indicates a substituted or unsubstituted alkylene group, and Z indicates OH, SH, NH2, or NHR. 4 , where R 4 Indicates substituted or unsubstituted alkyl or (hetero)aryl groups, and R 3 Represents a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or a group having the following formula: Where R' 1 and R' 2 Each of these can independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R'. 1 and R' 2 Together they form a shape with the formula -R' 1 -R' 2 - a divalent group, wherein -R' 1 -R' 2 - indicates a substituted or unsubstituted alkylene group, and Z' indicates OH, SH, NH2, or NHR'. 4 , where R' 4 Indicates substituted or unsubstituted alkyl or (hetero)aryl groups. The polymerizable composition is obtained from polymerizable compounds such that, on the one hand, the polymerizable compound used to prepare the prepolymer and on the other hand, the polymerizable compound added to the prepolymer in the polymerizable composition are used in amounts such that the molar ratio of SH / alkynyl groups present in all of the polymerizable compounds is greater than or equal to 7. The polymerizable composition is obtained from polymerizable compounds such that, on the one hand, the polymerizable compound used to prepare the prepolymer and on the other hand, the polymerizable compound added to the prepolymer in the polymerizable composition are adapted to be used in amounts such that the molar ratio of NCX / alkynyl groups present in all of the polymerizable compounds is greater than or equal to 6, where X is O or S.

2. The polymerizable composition of claim 1, wherein, The polymerizable compound is selected from compounds having formula (II): Where R 1 and R 2 Each of these can independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a (hetero)aryl group, or R. 1 and R 2 Together they form a form with -R 1 -R 2 - a divalent group, wherein -R 1 -R 2 - indicates a substituted or unsubstituted alkylene group.

3. The polymerizable composition of claim 1, wherein, The polymerizable compound is selected from compounds having the following formula: 。 4. The polymerizable composition as claimed in any of the preceding claims, wherein, The polymerizable composition is obtained from a polymerizable compound such that the compound having formula (I) accounts for 0.15% to 4% by weight of the total weight of the polymerizable compound used to prepare the prepolymer and the polymerizable compound added to the prepolymer in the polymerizable composition.

5. The polymerizable composition as claimed in any of the preceding claims, wherein, The polythiol is a compound having the following formula: R 5 (SH) n1 (III) Where n1 represents an integer from 2 to 6, and R 5 It indicates an aliphatic, alicyclic, heterocyclic, or aromatic group.

6. The polymerizable composition as claimed in any of the preceding claims, wherein, The polythiols are selected from the group consisting of: pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(2-mercaptoacetate), tri(3-mercaptopropionate)trimethylolpropane, tri(2-mercaptoacetate)trimethylolpropane, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol, ethylene glycol bis(3-mercaptopropionate), butanediol bis(3-mercaptopropionate), 2-mercaptoethyl 2-mercaptoacetic acid, 2-mercaptoethyl 3-mercaptopropionic acid, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane. The compounds include methyl-1,11-dimercapto-3,6,9-trithiaundecane, 2,5-bis(mercaptomethyl)-1,4-dithiaane, bis(mercaptoethyl)sulfide, 1,1,3,3-tetra(mercaptomethylthio)propane, 4,6-bis(mercaptomethylthio)-1,3-dithiaane, 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithiacyclobutane, 1,1,2,2-tetra(mercaptomethylthio)ethane, 3-mercaptomethyl-1,5-dimercapto-2,4-dithiapentane, tris(mercaptomethylthio)methane, pentaerythritol hexa(3-mercaptopropionate), tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, and ethane dithiol.

7. The polymerizable composition as claimed in any of the preceding claims, wherein, The polyisocyanate or polyisothiocyanate is a compound having formula (VI): R 6 (NCX) n2 (VI) Where X represents O or S, n2 represents an integer from 2 to 6, and R 6 It indicates an aliphatic, alicyclic, heterocyclic, or aromatic group.

8. The polymerizable composition as claimed in any of the preceding claims, wherein, The polyisocyanate or polyisothiocyanate is selected from the group consisting of: toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, p-phenylene diisocyanate, phenylene 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(ethyl isocyanate) fumarate, isophorone diisocyanate, ethylene diisocyanate, dodecane-1,12-diisocyanate, cyclobutane Alkane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene-2,4-diisocyanate, tetramethylphenyldimethyl diisocyanate, hexahydrotoluene-2,6-diisocyanate, perhydrodiphenylmethane-2,4'-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, bis(isocyanomethyl)cyclohexane, dicyclohexylmethane diisocyanate, 2,5-bis(isocyanomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanomethyl)bicyclo-[2.2.1]-heptane, 1,5-naphthalene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate trimer and 1,6-hexamethylene diisocyanate trimer.

9. The polymerizable composition as claimed in any of the preceding claims, wherein, The polymerizable composition is obtained from polymerizable compounds such that, on the one hand, the polymerizable compound used to prepare the prepolymer and on the other hand, the polymerizable compound added to the prepolymer in the polymerizable composition are adapted to be used in an amount ranging from 0.9 to 1.1 for the molar ratio of (NCX group + alkynyl group) / SH group present in all of the polymerizable compounds, where X is O or S.

10. The polymerizable composition as claimed in any of the preceding claims, wherein, The polymerizable composition is obtained from polymerizable compounds such that, on the one hand, the polymerizable compound used to prepare the prepolymer and on the other hand, the polymerizable compound added to the prepolymer in the polymerizable composition are adapted to be used in an amount in which the molar ratio of NCX / SH groups present in all of the polymerizable compounds ranges from 0.7 to 1.2, where X is O or S.

11. An optical material obtained by polymerization of a polymerizable composition as described in any one of the preceding claims.

12. The optical material as described in claim 11 is further defined as a substrate for an optical lens.

13. The optical material of claim 12 is further defined as having a refractive index greater than or equal to 1.

50.

14. A prepolymer having thiol end groups, obtained by reacting a mixture of at least one polythiol and at least one polymerizable compound having formula (I) as defined in claim 1, wherein the molar ratio of SH / alkynyl groups of the polythiol and the polymerizable compound having formula (I) used to prepare the prepolymer is greater than or equal to 7.

15. A method for preparing an optical material, the method comprising the steps 1), 2), and 3), or 1'), 2'), and 3'): 1) A first component comprising at least one prepolymer having a thiol end group, said prepolymer being obtained by polymerization of a mixture of at least one polythiol and at least one polymerizable compound having formula (I) as defined in any one of claims 1 to 10 in the presence of at least one initiator. 2) Provide a second component comprising at least one polyisocyanate or polyisothiocyanate, 3) The first component and the second component are mixed together to form a polymerizable composition, and the polymerizable composition is thermally polymerized in the presence of at least one catalyst to obtain the optical material. or: 1') Provides a first component comprising at least one isocyanate or isothiocyanate end group having the formula -NCX, wherein X is O or S, said prepolymer being obtained by thermal polymerization of a mixture of at least one polyisocyanate or polyisothiocyanate and at least one polymerizable compound having formula (I) as defined in any one of claims 1 to 10 in the presence of at least one catalyst. 2') Provide a second component comprising at least one polythiol, 3') The first component and the second component are mixed together to form a polymerizable composition, and the polymerizable composition is polymerized in the presence of at least one initiator to obtain the optical material. The polymerizable composition is obtained from polymerizable compounds such that the polymerizable compound used, on the one hand, to prepare the prepolymer, and on the other hand, the polymerizable compound mixed with the prepolymer in the polymerizable composition, are used in amounts adapted such that the molar ratio of SH / alkynyl groups present in all of the polymerizable compounds is greater than or equal to 7. The polymerizable composition is obtained from polymerizable compounds such that the polymerizable compound used on the one hand to prepare the prepolymer and the polymerizable compound mixed with the prepolymer in the polymerizable composition on the other hand are used in an amount adapted such that the molar ratio of NCX / alkynyl groups present in all of the polymerizable compounds is greater than or equal to 6, where X is O or S.

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