Method for manufacturing polymer optical articles and compositions therefor

Abstract

The present invention relates to a method for manufacturing a polymeric optical article comprising: providing a polymerizable composition comprising: at least one polyallyl functional monomer comprising a small amount of oligomer; 0.5 to 2 wt.% of at least one aromatic peroxide as radical initiator. The polymerizable composition is cured according to a predetermined curing period, which makes it possible to obtain an optical article having improved characteristics without using a highly reactive radical initiator such as IPP. In addition, the productivity of the method is improved while the number of defects in the optical article is significantly reduced. The invention also relates to a polymerizable composition suitable for use in the above process.

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for the manufacture of polymeric optical articles and to compositions therefor. BACKGROUND

[0002] Polyallyl functional monomers are polymerized using a free radical initiator to produce hard polymers. Many of these polymers are substantially transparent to visible light, substantially colorless, have a refractive index of about 1.45 to about 1.6, and have good mechanical resistance. For these reasons, these monomers are widely used as precursors for optical articles such as optical lenses and optical lens blanks, safety lenses, and flat or curved transparent sheets. The light transmission properties can be modified by introducing dyes, light absorbing compounds, pigments, etc. into the polymerizable composition containing the monomers prior to polymerization, or by dyeing the polymer.

[0003] The polymerization of polyallyl functional monomers is generally carried out in the presence of a peroxide initiator, in particular a dialkyl percarbonate such as, for example, diisopropyl peroxide carbonate (IPP) or a mixture of IPP with di-sec-butyl peroxide carbonate, which makes it possible to obtain polymerized products having excellent optical properties, in particular transparency and low coloration.

[0004] However, dialkyl percarbonate initiators, in particular IPP, have the drawback of being very expensive and very thermally unstable, with explosive decomposition, so that they require quite stringent transport and storage conditions. Even in the case where they are formulated in diluted form using, for example, a dilution polyallyl functional monomer, they still require transport and storage temperatures as low as about -20°C to -10°C.

[0005] In the prior art, peroxide initiators are also known which are stable at ambient temperature (also known as ambient stable initiators: ASI), thus having the potential to overcome the above-mentioned drawbacks of dialkyl percarbonate initiators. However, ASI compounds (for example, diacyl peroxides, alkyl peroxyesters, alkyl peroxyketones and peroxy monocarbonates) also have some drawbacks which have hitherto limited their use in practice as initiators for the polymerization of polyallyl functional monomers.

[0006] For example, certain ASI compounds have a low solubility in polyallyl functional monomers, thus leading to unsatisfactory levels of solidification of the polymerized material. Furthermore, polymerized materials obtained using ASI compounds such as diacyl peroxide initiators (for example, benzoyl peroxide) exhibit considerable yellowing and poor resistance to UV light. In addition, materials obtained by polymerization using ASI compounds generally exhibit a relatively high level of hardness and brittleness and high shrinkage, compared to polymerized materials obtained using IPP as initiator.

[0007] As used herein, the term "shrinkage" (S) refers to the ratio wherein Df is the density of the final thermoset polymer at 23°C, D1 is the density of the liquid polymerizable composition at 23°C. The term "percentage of shrinkage" is equal to the shrinkage multiplied by one hundred. pol mon As used herein, the term "shrinkage" (S) refers to the ratio

[0008] High shrinkage levels are particularly detrimental in casting processes, such as those commonly used to prepare ophthalmic lenses and ophthalmic lens blanks, wherein a liquid monomeric composition is introduced into a mold and then polymerized into a final polymer in the thermoset state.

[0009] When the polymerization is carried out in the presence of an ASI compound as initiator, in fact, the liquid polymerizable composition has to be heated to a relatively high initial temperature, for example about 60°C in the case of BPO (i.e. much higher than about 40°C in the case of IPP), in order to start the curing cycle and even the polymerization reaction. However, this initial heating step is accompanied by a volume expansion of the polymerizable composition within the mold, which leads to a non-negligible decrease of the density of the polymerizable composition to be cured. Since the initial volume expansion is higher than the one that occurs when the same polymerizable composition is cured with IPP or other non-ASI initiators, the shrinkage observed for the polymerized material cured with ASI initiators is significantly higher than for the same polymerizable composition cured with IPP or other non-ASI initiators.

[0010] This high shrinkage level brings many defects in the polymerized material and often causes breakage of the polymerized material or of the mold, thus leading to a low overall yield of the manufacturing process using ASI initiators.

[0011] In the prior art, it is known that shrinkage can be reduced by using specific polymerizable compositions. For example, when the multi-allyl functional monomer is diethylene glycol bis(allyl carbonate) having the following formula (II), wherein n is a positive integer (for example in the range of 1-10).

[0012] ​Examples of these mono- or poly-ethylenically unsaturated compounds, also referred to as co-monomers or reactive diluents, are mono- or poly-ethylenically unsaturated compounds such as the vinyl esters of versatic acid 9 and 10. The co-monomer can be a liquid component with a lower density of polymerizable double bonds (i.e. the number of double bonds per unit mass of the compound) compared to the diethylene glycol bis(allyl carbonate) monomer. These co-monomers enable to obtain a final polymeric material with a lower crosslinking level (i.e. a lower value of the term D pol in the shrinkage equation above) and thus with a lower final shrinkage compared to the polymeric material obtained from the diethylene glycol bis(allyl carbonate) monomer without co-monomer.

[0013] Alternatively, or in addition to the above effect, the co-monomer can have a higher density (i.e. mass / volume ratio) than the diethylene glycol bis(allyl carbonate) monomer, so that the cast polymeric composition containing the polyallyl functional monomer and the co-monomer has an increased density (i.e. a higher value of the term D mon in the shrinkage equation above) and thus a lower final shrinkage. This is for example the case for compounds with a high molar mass or a multi-functional structure, i.e. having three or more ethylenically unsaturated functional groups per molecule, as disclosed in US 4144262, wherein the compounds are also used in neat form as an alternative to the use of the diethylene glycol bis(allyl carbonate) monomer.

[0014] This approach of using co-monomers to reduce shrinkage is described for example in WO 2004090002 A1, US 2021 / 0263197 A1, EP 3381951 A1 and EP 0241997.

[0015] In an alternative approach, when the polyallyl functional monomer is the diethylene glycol bis(allyl carbonate) of formula (II) above, the polymeric composition can comprise a relatively high content of oligomeric species, i.e. species of formula (II) with n equal to 2 or more. As these oligomeric species have a lower density of polymerizable double bonds compared to the linear species of the diethylene glycol bis(allyl carbonate) monomer (i.e. species of formula (II) with n = 1 ), they enable to obtain a final polymeric material with a lower crosslinking level (i.e. a lower value of the term D pol in the shrinkage equation above) and thus with a lower final shrinkage.

[0016] This approach of reducing shrinkage is described for example in WO 00 / 27794 and WO 2017 / 168325 A1. SUMMARY

[0017] PROBLEMS TO BE SOLVED BY THE INVENTION Another method to mitigate shrinkage known in the art is based on the introduction of a liquid prepolymer into the mold, which is then polymerized to obtain the final thermoset polymer. The prepolymer is usually prepared by partially polymerizing a multi allyl functional monomer to consume a fraction of the allyl groups. However, the partial polymerization is stopped before more than a small amount of gelation occurs, so that the prepolymer can be introduced into the mold as a liquid. An example of this technology is described in US 6057411.

[0018] However, the methods and monomer compositions of the prior art suitable for reducing shrinkage involve high costs due to the use of additional raw materials (i.e. comonomers) and complex preparation processes (provision of specific multi allyl monomers and prepolymers).

[0019] Furthermore, the use of specific multi allyl monomers and prepolymers according to the prior art can have a detrimental impact on process productivity. In fact, the higher reactivity of the prepolymers makes it necessary to prepare small batches to avoid undesired premature gelation of the material in the process equipment. Moreover, the high molecular weight of the specific multi allyl monomers and prepolymers leads to higher viscosity and density of the material to be processed and, consequently, to longer times for filling the glass mold, resulting in reduced productivity.

[0020] Therefore, there is a need in the prior art for a new method to polymerize multi allyl functional monomers by means of environmentally stable polymerization initiators.

[0021] Means for solving the problem It has now been found a method which enables to easily polymerize (i.e. cure) multi allyl functional monomers, as defined hereinafter, by means of environmentally stable polymerization initiators, to obtain polymer materials with good mechanical and optical properties, substantially comparable to those of multi allyl functional monomers polymerized using IPP initiators.

[0022] The method of polymerization (i.e. curing) of the multi allyl functional monomers described herein is able to substantially minimize the detrimental effects associated with the shrinkage occurring in the methods of the prior art employing ASI compounds as initiators, thus providing a very efficient and productive way for the manufacturing of polymeric optical articles.

[0023] The present application is based on the observation that curing a polymerizable composition, comprising multi allyl functional monomers, as defined hereinafter, and a relatively small amount of environmentally stable aromatic peroxide (e.g. benzoyl peroxide), in a way that the composition is heated at a sufficiently slow speed, as defined hereinafter, brings to a gradual gelation and curing of the polymerizable composition without significant volume expansion within the mold. Therefore, the method described herein minimizes the occurrence of cracks and optical defects in the polymeric articles, with the result of increasing the process productivity.

[0024] In particular, according to the present application, the curing cycle comprises the steps of subjecting the polymerizable composition to an isothermal heat treatment at a temperature (T A ) close to the 10 hours half-life temperature of the aromatic peroxide, and maintaining the composition at this temperature T A for a certain period of time (as defined hereinafter), followed by a step of further heat treatment of the polymerizable composition by raising its temperature from the temperature T A to a final temperature (T F ) in the range of 80°C to 120°C. Then, the curing is completed to obtain a final polymeric material (hereinafter also referred to as "polymerized product").

[0025] Without wishing to be bound by any theory, it is believed that by using a small amount of aromatic peroxide initiator (i.e. lower than those usually used in the prior art for ASI compounds) and in combination with a curing cycle according to the temperature-time profile described herein, a more uniform distribution of the heat generated by the exothermic polymerization reaction within the mass of the polymerizable composition is achieved, and thus a more uniform polymerization reaction of the multi allyl functional monomers. This in turn leads to a polymeric material having the desired mechanical and optical properties, with few or no defects (e.g. flow marks). Moreover, since the isothermal treatment minimizes the volume expansion of the polymerizable composition within the mold, the difference between the density of the final polymeric material and the density of the liquid polymerizable composition at the starting temperature of the curing cycle remains low, with a beneficial effect in terms of shrinkage.

[0026] In one embodiment, these results can be achieved without resorting to the use in the polymerizable composition of any co-monomer, pre-polymer or multi allyl functional monomer requiring a complex preparation process. This is advantageous in that it enables the manufacture of an optical article starting from a multi allyl functional monomer obtained from a preparation process that is easier and more cost-effective, together with a more inexpensive and more handleable radical initiator.

[0027] Moreover, unlike the prior art, the use of a relatively small amount of aromatic peroxide (i.e. lower than the usual amount of about 3 wt.% based on the multi allyl functional monomer) has the additional advantage of keeping the yellowness and the hardness of the final optical article at an acceptable level.

[0028] Furthermore, although the duration of the manufacturing process is lengthened (about 20 to 48 hours), the present application allows the use of an environmentally stable initiator instead of more unstable peroxides (such as IPP), with significant advantages in terms of personnel safety, manufacturing costs, and transportation and storage conditions.

[0029] Thus, according to a first aspect, the present application relates to a method for manufacturing a polymeric optical article, the method comprising: A. providing a polymerizable composition comprising: - at least one multiallelically functional monomer of formula (I): wherein X represents a divalent to hexavalent radical derived from a linear or branched aliphatic polyol having 3 to 12 carbon atoms, or a divalent to hexavalent radical derived from a cycloaliphatic polyol having 5 to 16 carbon atoms, and n represents an integer from 2 to 6; wherein the multiallelically functional monomer of formula (I) comprises 70 wt.% or more, preferably 80 wt.% or more, of multiallelically functional monomers of formula (I) for which n is equal to 2, the weight percentage being based on the total weight of the multiallelically functional monomers of formula (I); - 0.5 to 2 wt.% of at least one aromatic peroxide as a free radical initiator, the weight percentage being based on the total weight of the multiallelically functional monomers; B. curing the polymerizable composition according to a curing cycle comprising: B1. heating the polymerizable composition to an activation temperature T A ; B2. maintaining the polymerizable composition at temperature T A for a period of 8 to 24 hours; B3. heating the polymerizable composition after step B2 to a final temperature T F ; B4. maintaining the polymerizable composition at final temperature T F to obtain an optical article.

[0030] According to a second aspect, the present application relates to a polymeric optical article obtained by the method according to the first aspect.

[0031] According to a third aspect, the present application relates to an ophthalmic lens comprising a polymeric optical article according to the second aspect.

[0032] According to a fourth aspect, the present application relates to a polymerizable composition comprising: - at least one multiallelically functional monomer of formula (I): wherein X represents a divalent to hexavalent radical derived from (al) a linear or branched aliphatic polyol having 3 to 12 carbon atoms, or (bl) a divalent to hexavalent radical derived from a cycloaliphatic polyol having 5 to 16 carbon atoms, and n represents an integer from 2 to 6; The polyallyl functional monomer having formula (I) comprises 70 wt.% or more, preferably 80 wt.% or more of n equal to 2 polyallyl functional monomers having formula (I), and this weight percentage is based on the total weight of the polyallyl functional monomers having formula (I). - 0.5 to 2 wt.% of at least one aromatic peroxide as a free radical initiator, the weight percentage being based on the total weight of the polyallyl functional monomers.

[0033] According to a preferred embodiment of the invention, the polymerizable composition does not contain olefinic unsaturated compounds that are different from polyallyl functional monomers having formula (I).

[0034] According to a preferred embodiment, the polyallyl functional monomer is a diethylene glycol bis(allyl carbonate) compound of formula (II): Where n is an integer equal to or greater than 1 and equal to or less than 10; The diethylene glycol bis(allyl carbonate) compound of general formula (II) comprises 70 wt.% or more, preferably 80 wt.% or more of the diethylene glycol bis(allyl carbonate) compound of formula (II) with n equal to 1, the weight percentage being based on the total weight of the diethylene glycol bis(allyl carbonate) compound of general formula (II).

[0035] According to a preferred embodiment of the invention, the polymerizable composition does not contain olefinically unsaturated compounds that are different from diethylene glycol bis(allyl carbonate) compounds having formula (II).

[0036] Further features of the invention are the subject of the dependent claims appended to this specification.

[0037] The compositions of the present invention may comprise, and be substantially composed of, or consist of, the basic components described herein and optional ingredients. In this document, “substantially composed of” means that the composition or components may include other ingredients, provided that such other ingredients do not substantially alter the essential characteristics and novel features of the claimed composition or method.

[0038] As used herein, the articles “a,” “an,” and “the” should be understood to include one or more, and the singular includes the plural unless there is an obvious other meaning. This is done for convenience and to give a general meaning to the published content.

[0039] Except as provided in the embodiments, or as otherwise specified, all figures used in the specification and claims to indicate the amounts of ingredients, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Detailed Implementation

[0040] Polyallyl functional monomers.

[0041] The polymerizable composition according to the present application comprises at least one polyallyl functional monomer having formula (I). In most cases, the polymerizable composition comprises a mixture of polyallyl functional monomers having formula (I) (i.e., a monomer composition) comprising 70 wt.% or more, preferably 80 wt.% or more, of polyallyl functional monomers having formula (I) equal to 2, the weight percent being based on the total weight of the mixture.

[0042] The polyallyl functional monomer can be selected from a variety of liquid polyallyl compounds, which can include monomers and oligomers having at least two allyl groups as the polymerizable functional group.

[0043] The polyallyl functional monomer can comprise, for example, compounds containing two or more allyl groups, such as diallyl esters and diallyl carbonates.

[0044] In one embodiment, the polyallyl functional monomer comprises a liquid poly(allyl carbonate) of a polyhydroxy organic material. Examples of such monomers include poly(allyl carbonates) of linear or branched aliphatic polyols, and poly(allyl carbonates) of cycloaliphatic-containing polyols. These monomers are known and can be prepared by procedures known in the art.

[0045] In one embodiment, the polyallyl functional monomer is selected from the group consisting of diethylene glycol bis(allyl carbonate), ethylene glycol bis(allyl carbonate), oligomers of diethylene glycol bis(allyl carbonate), oligomers of ethylene glycol bis(allyl carbonate), and mixtures thereof.

[0046] In formula (I) as defined above, X represents a divalent to hexavalent group derived from (a1) a linear or branched aliphatic polyol having 3 to 12 carbon atoms; or (b1) a divalent to hexavalent group derived from a cycloaliphatic polyol having 5 to 16 carbon atoms. These polyols generally contain 2 to 6 hydroxyl groups in the molecule, and it is preferred that these polyols can contain 2 to 4 hydroxyl groups in the molecule.

[0047] Examples of the aliphatic polyol (a1) include diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, glycerol, trimethylolpropane, tri(hydroxyethyl) isocyanurate, pentaerythritol, dipentaerythritol, and the like.

[0048] Examples of the alicyclic polyol (b1) include 1,4-dihydroxymethylcyclohexane, 4,8- di(hydroxymethyl)-[5.2.1.0 2,6 ]tricyclodecane, glycerol, trimethylolpropane, tris(hydroxyethyl) isocyanurate, pentaerythritol, dipolyglycerol, ditrimethylolpropane, dipentaerythritol, and the like.

[0049] Specific examples of the compound containing two or more allyloxycarbonyl groups include an allyl carbonate polymerizable compound (A1), an allyl ester polymerizable compound (A2), and a polymerizable compound (A3) containing at least one of an allyl carbonate group and an allyl ester group.

[0050] The compound of formula (I) containing two or more allyloxycarbonyl groups is a liquid product at room temperature, and has a viscosity of 10 to 1000 cSt measured at 25°C.

[0051] As used herein, the kinematic viscosity of a multi-allyl functional monomer or polymerizable composition is determined according to ASTM D446 using a KPG Ubbelohde viscometer (capillary type 1C or 2C).

[0052] As described above, the multi-allyl functional monomer of formula (I) can be composed of at least one monomer of formula (I) with n = 2, or can be a mixture of the at least one monomer of formula (I) with n = 2 and at least one oligomer thereof, i.e., at least one compound of formula (I) with n of 3 to 6. The oligomer is a poly(allyl carbonate) in which two or more molecules of a polyol are connected via a carbonate group produced by an ester exchange reaction of an allyl carbonate produced in the preparation step and a polyol.

[0053] Specific examples of the polyol forming the group X in formula (I) include diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-dihydroxymethylcyclohexane, 4,8-di(hydroxymethyl)-[5.2.1.0 2,6 ]tricyclodecane, glycerol, trimethylolpropane, tris(hydroxyethyl) isocyanurate, pentaerythritol, dipolyglycerol, ditrimethylolpropane, dipentaerythritol, and the like.

[0054] The polyol forming the group X in formula (I) can also be a chain-extended polyol such as a lactone chain-extended polyol and an alkylating oxygen chain-extended polyol. By chain-extended polyol is meant a reaction product of a terminal hydroxyl group of a polyol and a suitable reactant such as a lactone or an alkylating oxygen.

[0055] Examples of lactone chain-extended polyols include: ε-caprolactone chain-extended diethylene glycol, ε-caprolactone chain-extended dipropylene glycol, ε-caprolactone chain-extended triethylene glycol, ε-caprolactone chain-extended tetraethylene glycol, ε-caprolactone chain-extended pentaerythritol, and ε-caprolactone chain-extended trimethylolpropane.

[0056] Examples of alkylate chain-extended polyols include: ethylene oxide or propylene oxide chain-extended diethylene glycol, ethylene oxide or propylene oxide chain-extended dipropylene glycol, ethylene oxide or propylene oxide chain-extended triethylene glycol, ethylene oxide or propylene oxide chain-extended tetraethylene glycol, ethylene oxide or propylene oxide chain-extended pentaerythritol, ethylene oxide or propylene oxide chain-extended trimethylolpropane.

[0057] Examples of allyl carbonate compounds thus include at least one compound selected from the group consisting of: bis(allyl carbonate) compounds of at least one diol selected from the group consisting of diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-bishydroxymethylcyclohexane, and 4,8-bis(hydroxymethyl)-[5.2.1.0 2,6 ]tricyclodecane; tri(allyl carbonate) compounds of at least one triol selected from the group consisting of glycerol, trimethylolpropane, and tris(hydroxyethyl) isocyanurate; tetra(allyl carbonate) compounds of at least one tetrol selected from the group consisting of pentaerythritol, dipentaerythritol, and bistrimethylolpropane; dimeric pentaerythritol hexa(allyl carbonate) compounds; and mixed poly(allyl carbonate) compounds of at least two compounds selected from the group consisting of diols, triols, tetraols, and dimeric pentaerythritol.

[0058] For example, in the case where the diol is diethylene glycol and neopentyl glycol, "bis(allyl carbonate) of a mixture of at least two diols" is obtained as a mixture of the following monomer component and oligomer component: Monomer component: (1) diethylene glycol bis(allyl carbonate); (2) neopentyl glycol bis(allyl carbonate); Oligomer component: (3) an oligomer containing only hydrocarbons (and ethers) derived from diethylene glycol (a compound having the following structure: wherein both of the hydroxyl groups of a compound in which diethylene glycol is linearly oligomerized via carbonate bonds are replaced with allyl carbonate groups); (4) oligomers containing only hydrocarbons derived from neopentyl glycol (compounds having the following structure: wherein both hydroxyl groups of a compound in which neopentyl glycol is linearly oligomerized via carbonate bonds are replaced by allyl carbonate groups); (5) complex oligomers containing both hydrocarbons (and ethers) derived from diethylene glycol and hydrocarbons derived from neopentyl glycol in the same molecule (compounds having the following structure: wherein diethylene glycol and neopentyl glycol are linearly oligomerized via carbonate bonds in any order in the same molecule, both hydroxyl groups of the compound are replaced by allyl carbonate groups).

[0059] The following are preferred examples of allyl carbonate polymerizable compounds of formula (II) suitable for the purposes of the present application: (i) a mixture of diethylene glycol bis (allyl carbonate) and oligomers thereof, wherein diethylene glycol bis (allyl carbonate) can be defined by formula (IIa) Further, oligomers of diethylene glycol bis (allyl carbonate) can be defined by formula (IIb) wherein n is equal to or greater than 2 and equal to or less than 10.

[0060] For example, compound (IIa) can be manufactured by reacting diethylene glycol bis (chloroformate) with allyl alcohol, as described in "Encyclopedia of Chemical Technology", Kirk-Othmer, 3rd edition, vol. 2, pages 111-112. Diethylene glycol bis (allyl carbonate) (formula (IIa)) and mixtures of oligomers thereof (formula (IIb)) can be easily prepared by ester replacement between diallyl carbonate and diethylene glycol in the presence of a basic catalyst, for example as described in EP 35304. These mixtures typically contain up to about 80% by weight of oligomers; (ii) a mixture of bis (allyl carbonate) compounds of mixtures of diethylene glycol and neopentyl glycol and oligomers thereof The bis (allyl carbonate) compounds are identical to the bis (allyl carbonate) compounds of aspect (i) above, except that diethylene glycol is replaced with a mixture of diethylene glycol and neopentyl glycol; (iii) a mixture of poly (allyl carbonate) compounds of mixtures of diethylene glycol and tris (hydroxyethyl) isocyanurate and oligomers thereof The poly (allyl carbonate) compounds can be obtained by ester replacement of diallyl carbonate with a mixture of diethylene glycol and tris (hydroxyethyl) isocyanurate, for example as described in US 4,812,545.

[0061] (iv) a mixture of a poly(allyl carbonate) compound of a mixture of diethylene glycol and trimethylolpropane with oligomers thereof.

[0062] The poly(allyl carbonate) compound is the same as the poly(allyl carbonate) compound of aspect (iii) above except that trimethylolpropane is substituted for tri(hydroxyethyl) isocyanurate.

[0063] (v) a mixture of a poly(allyl carbonate) compound of a mixture of diethylene glycol and pentaerythritol with oligomers thereof.

[0064] The poly(allyl carbonate) compound is the same as the poly(allyl carbonate) compound of aspect (iii) above except that pentaerythritol is substituted for tri(hydroxyethyl) isocyanurate.

[0065] (vi) a mixture of a poly(allyl carbonate) compound of a mixture of diethylene glycol, neopentyl glycol, and pentaerythritol with oligomers thereof.

[0066] The poly(allyl carbonate) compound is the same as the poly(allyl carbonate) compound of aspect (v) above except that diethylene glycol and neopentyl glycol are substituted for diethylene glycol.

[0067] (vii) a poly(allyl carbonate) mixture comprising: a mixture of a poly(allyl carbonate) compound of a mixture of diethylene glycol, neopentyl glycol, and pentaerythritol with oligomers thereof, and a mixture of a diethylene glycol bis(allyl carbonate) compound with oligomers thereof.

[0068] In a preferred embodiment, the polyallyl-functional monomer comprises or is a diethylene glycol bis(allyl carbonate) compound of formula (II) wherein n is equal to or greater than 1 and equal to or less than 10.

[0069] Preferably, the polyallyl-functional monomer comprises 70 wt.% or more, preferably 80 wt.% or more, of the diethylene glycol bis(allyl carbonate) compound of formula (II) wherein n is equal to 1 (i.e. the monomeric compound of formula (Ha) above), the weight percentage being based on the weight of the polyallyl-functional monomer.

[0070] The above wt.% relative concentrations of monomeric species (n = 1) and oligomeric species (n = 2-10) of formula (lib) in the polyallyl-functional monomer can be determined by known methods. In particular, the concentration values can be determined by means of HPLC or GPC analysis under conditions enabling peaks corresponding to sufficient separation of the monomeric species and each oligomeric species to be obtained, followed by calculation of the percentage area of the chromatographic peak associated with each monomeric and oligomeric species.

[0071] In one embodiment, the multi-allyl functional monomer comprises, or is the reaction product (RP) of components comprising: diallyl carbonate (A); one or more linear or branched aliphatic diols containing 3 to 10 carbon atoms in the molecule (B); and optionally, a linear or branched aliphatic polyol containing 4 to 20 carbon atoms and 3 to 6 hydroxyl groups in the molecule (C); wherein the molar ratio A / (B+C) is in the range of 4 / 1 to 20 / 1 and the amount of optional component (C) in the mixture (B+C) is equal to or less than 5 wt.% relative to the weight of the mixture (B+C).

[0072] Preferably, the molar ratio A / (B+C) is in the range of 5 / 1 to 10 / 1 and the amount of (C) in the mixture (B+C) is equal to or less than 3 wt.% relative to the weight of the mixture (B+C).

[0073] The diol (B) is a linear or branched aliphatic diol, preferably containing 3 to 10 carbon atoms in the molecule.

[0074] Examples of suitable diols (B) are diethylene glycol, triethylene glycol, tetraethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-propanediol, neopentyl glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol and 1,4-cyclohexanedimethanol.

[0075] Preferably, the diol (B) is selected from the group consisting of diethylene glycol, neopentyl glycol and combinations thereof.

[0076] The polyol (C) is a linear or branched aliphatic polyol, preferably containing 4 to 20 carbon atoms and 3 to 6 hydroxyl groups in the molecule.

[0077] Examples of suitable polyols (C) are pentaerythritol, trimethylolpropane, dipentaerythritol, ditrimethylolpropane and tris(hydroxyethyl) isocyanurate.

[0078] Preferably, the polyol (C) is selected from the group consisting of pentaerythritol, trimethylolpropane and combinations thereof.

[0079] The multi-allyl functional monomer can be obtained as a reaction product (RP) by reacting diallyl carbonate (A) with a diol (B) or a mixture of diol (B) and polyol (C) under transesterification conditions and in the presence of a basic catalyst, as described for example in WO 2004 / 090002.

[0080] The reaction product (RP) has a kinematic viscosity at 25°C preferably in the range of 10 cSt to 300 cSt, more preferably 10 to 100 cSt, further more preferably 10 to 40 cSt. Preferably, the density of the reaction product RP at 25°C is in the range of 1.1 g / ml to 1.3 g / ml.

[0081] The reaction product (RP) is typically obtained as a mixture of the allyl carbonate species of components (B) and (C) (if present) in monomeric and oligomeric form, and as a mixture in the form of mixed oligomeric allyl carbonates of said components (B) and (C), the relative amounts of the allyl carbonate species depending mainly on the selected ratio of reagents (A), (B) and (C).

[0082] Polymerizable comonomers.

[0083] The polymerizable composition according to the present application can also contain an ethylenically unsaturated compound (as a monomer or an oligomer) capable of polymerizing with the above-described polyallyl functional monomer. Here, the optional ethylenically unsaturated compound is also referred to as a "comonomer". Examples of suitable comonomers include: aromatic vinyl compounds such as styrene, a-methylstyrene, vinyltoluene, chlorostyrene, chloromethylstyrene, and divinylbenzene; mono (meth) acrylate alkyl esters such as (meth) acrylate methyl ester, (meth) acrylate n-butyl ester, (meth) acrylate n-hexyl ester, (meth) acrylate cyclohexyl ester, (meth) acrylate 2-ethylhexyl ester, (meth) acrylate methoxydiethylene glycol ester, (meth) acrylate methoxypolyethylene glycol ester, (meth) acrylate 3-chloro-2-hydroxypropyl ester, (meth) acrylate stearyl ester, (meth) acrylate lauryl ester, (meth) acrylate phenyl ester, (meth) acrylate glycidyl ester, and (meth) acrylate benzyl ester, (meth) acrylate 2-hydroxyethyl ester, (meth) acrylate 2-hydroxypropyl ester, (meth) acrylate 3-hydroxypropyl ester, (meth) acrylate 3-phenoxy-2-hydroxypropyl ester, and (meth) acrylate 4-hydroxybutyl ester; di(meth) acrylates such as di(meth) acrylate ethylene glycol ester, di(meth) acrylate diethylene glycol ester, di(meth) acrylate triethylene glycol ester, di(meth) acrylate polyethylene glycol ester, di(meth) acrylate 1,3-butanediol ester, di(meth) acrylate 1,6-hexanediol ester, di(meth) acrylate neopentyl glycol ester, di(meth) acrylate polypropylene glycol ester, 2-hydroxy-1,3-di(meth) acryloyloxypropane, 2,2-bis[4-((meth) acryloyloxyethoxy)phenyl]propane, 2,2-bis[4-((meth) acryloyloxydiethoxy)phenyl]propane, and 2,2-bis[4-((meth) acryloyloxypolyethoxy)phenyl]propane; tri(meth) acrylates such as tri(meth) acrylate trimethylolpropane, and tetra(meth) acrylate tetramethylolmethane; and tetra(meth) acrylates such as tetra(meth) acrylate tetramethylolmethane. These comonomers can be used alone or in combination of two or more. In the above description, "(meth) acrylate" means "methacrylate" or "acrylate", and "(meth) acryloyloxy" means "methacryloyloxy" or "acryloyloxy".

[0084] The total amount of the comonomer in the polymerizable composition according to the present application can be 1 to 80% by weight, particularly 1 to 50% by weight, more particularly 2 to 20% by weight, even more particularly 3 to 10% by weight, based on the total weight of the polymerizable composition.

[0085] In a preferred embodiment, the polymerizable composition does not contain additional ethylenically unsaturated compounds, meaning that no polymerizable co-monomer is added to the polymerizable composition; thus, the only polymerizable compound present in the polymerizable composition is the multi-allyl functional monomer of formula (I) or (II).

[0086] In a preferred embodiment, the polymerizable composition contains a multi-allyl functional monomer that is a diethylene glycol bis(allyl carbonate) compound of formula (II) for which n is an integer equal to or greater than 1 and equal to or less than 10, and does not contain ethylenically unsaturated compounds as co-monomers; thus, the only polymerizable compound present in the polymerizable composition is said diethylene glycol bis(allyl carbonate) compound of formula (II).

[0087] In an embodiment, the polymerizable composition contains a multi-allyl functional monomer that is the above reaction product (RP) of components comprising diallyl carbonate (A), one or more aliphatic diols (B), and optionally an aliphatic polyol (C), and the polymerizable composition does not contain ethylenically unsaturated compounds as co-monomers; thus, the only polymerizable compound present in the polymerizable composition is the reaction product (RP) of components A, B, and optionally C.

[0088] In an embodiment, the multi-allyl functional monomer present in the polymerizable composition is not a pre-polymer, i.e., the multi-allyl functional monomer has not been partially polymerized to consume a portion of the allyl groups prior to use in the preparation of the polymerizable composition. Indeed, advantages of the present invention include the ability to use a multi-allyl functional monomer of simple construction and preparation to obtain a polymerized optical article with very low shrinkage without resorting to the preparation of pre-polymers and / or co-monomers.

[0089] In an embodiment, the polymerizable composition does not contain any polymerizable components that have been pre-partially polymerized.

[0090] Radical polymerization initiator According to the present invention, the polymerizable composition contains at least one free radical polymerization initiator. The free radical initiator is an aromatic peroxide compound. Preferably, the aromatic peroxide initiator is a compound having the following general formula (Fl): wherein X is selected from the group consisting of: hydrogen, Ci to C 12 alkoxy, chlorine, and bromine. In an embodiment, X is selected from the group consisting of hydrogen, Ci to C lto C4alkoxy or bromine. Examples of suitable aromatic peroxide initiators include benzoyl peroxide (BPO), di(p-methoxybenzoyl) peroxide, di(p-ethoxybenzoyl) peroxide, di(p- propoxybenzoyl) peroxide, di(p-isopropoxybenzoyl) peroxide, di(p-butoxybenzoyl) peroxide, and di(p-chlorobenzoyl) peroxide. An especially preferred initiator is benzoyl peroxide [CAS 94-36-0].

[0091] The half-life of a free radical initiator at any particular temperature is defined as the time for the initiator to lose half of its activity. It is determined by studying the kinetics of decomposition of the initiator. The 10 hour half-life temperature of an initiator is the temperature at which half of the initiator initially present decomposes within 10 hours.

[0092] The rate of decomposition of the initiator in the aromatic solvent monochlorobenzene is measured and thus the half-life temperature is determined by periodically sampling the peroxide solution maintained at several selected constant temperatures and determining the amount of undecomposed peroxide remaining in the sampled solution by conventional iodometric titration techniques. Such half-life measurement techniques are well known to those skilled in the art. Suitable techniques for determining such half-life temperatures in the same solvent using differential scanning calorimetry to provide a direct measurement of the desired half-life temperature are also known to those skilled in the art and can be used in place of the iodometric measurement. Both techniques provide equivalent results for the same solvent within the expected standard experimental deviation of the procedure. It is well known in the art that the half-life temperature depends on the solvent in which the determination is made, and therefore, in order to make an accurate comparison of the half-life temperature of one peroxide to another, the solvent in which the half-life is determined must be selected.

[0093] Preferably, the aromatic peroxide initiator suitable for use in the present application has a 10 hour half-life temperature equal to or greater than 55°C, more preferably equal to or greater than 60°C. For example, the 10 hour half-life temperature of the initiator can be in the range of 55°C to 100°C, preferably 60°C to 95°C, further more preferably 60°C to 85°C. An especially preferred aromatic peroxide is benzoyl peroxide, which has a 10 hour half-life temperature of 73°C.

[0094] In one embodiment, the polymerizable composition contains only one peroxide as the free radical polymerization initiator. However, when desired, a mixture of two or more aromatic peroxides having the same or different 10 hour half-life temperatures can be used, provided that the activation temperature T A .

[0095] The amount of free radical initiator or mixture of initiators in the polymerizable composition is in the range of 0.5 to 2 wt.%, preferably 0.7 to 1.8 wt.% based on the weight of the polyallyl functional monomers to be polymerized (the above wt% refers to the amount of pure initiator). An amount of initiator higher than 2 wt.% is not advantageous since they generate too much heat, thus increasing the risk of possible cracks and optical defects in the polymerized product; moreover, higher yellowness index and hardness are generated, which are not desirable for ophthalmic lenses.

[0096] Aromatic peroxide initiators are usually sold in the form of compositions containing a retarder and / or a stabilizer, such as alkyl benzoate-based retarders, phthalate-based retarders and cresol-based retarders, or water as a stabilizer. It has been observed that the use of initiators containing phthalate-based and cresol-based retarders can lead to polymerized optical articles having defects, so-called dots, which become particularly visible on coated lenses. Moreover, phthalate-based and cresol-based retarders have a relatively low solubility, which is reflected in a higher haze of the final polymerized product.

[0097] The use of water-stabilized peroxides can also have some drawbacks in the manufacturing process if the water content in the polymerizable composition before casting exceeds a certain concentration. For example, the presence of more than 0.5 wt% of residual water, based on the weight of the polymerizable composition, can actually lead to premature detachment of the optical article from the mold during the curing cycle, or to uneven transfer of the polyallyl functional monomers from one mold to another. However, since it is easier to remove water from the polymerizable composition before casting it into the mold (for example by degassing or purging the composition with an inert gas), it is preferred in one embodiment to use water-stabilized aromatic peroxides.

[0098] Especially preferred initiators are water-stabilized benzoyl peroxide, which is sold as a wet powder. Preferably, the water content is equal to or less than 50 wt%, more preferably equal to or less than 25 wt%, the weight percentage being based on the weight of the water-stabilized aromatic peroxide (e.g. BPO).

[0099] Other components.

[0100] The polymerizable composition can also comprise other additive compounds, such as internal mold release agents, UV and / or HEV light absorbers, resin modifiers (e.g. chain extenders, crosslinking agents, light stabilizers), antioxidants, fillers, adhesion promoters, bleaching agents, etc.

[0101] As an internal release agent, acidic phosphate esters or non-reactive silicone oils can be used, for example. Examples of acidic phosphate esters include monophosphate esters and diesters, and these substances can be used alone or in mixtures of two or more.

[0102] Examples of resin modifiers include olefin compounds containing cyclic sulfide compounds, alcohol compounds, amine compounds, epoxy compounds, organic acids and their anhydrides, (meth)acrylate compounds, etc.

[0103] Examples of suitable bleaching agents are those based on inorganic pigments or organic dyes dispersed in an allyl resin, such as those disclosed in WO 2021095774A1 and WO 2022224928A1 under the same applicant.

[0104] Examples of UV and / or HEV light absorbers include benzotriazole, benzophenone, triazine, and oxaloylaniline.

[0105] Preparation of optical materials.

[0106] According to the method of the present invention, the polymerizable composition can be prepared by mixing a polyallyl functional monomer, a free radical polymerization initiator and optional components (step A).

[0107] In one embodiment, step A includes combining a polyallyl functional monomer with benzoyl peroxide in a water-stabilized form.

[0108] The mixing of components is typically carried out at 25°C using conventional equipment. Because peroxides are stable at ambient temperature, the pot life of the polymerizable compositions is significantly longer compared to those containing IPP as an initiator.

[0109] According to a preferred embodiment, the composition is stirred until homogeneous, and then degassed and / or filtered under reduced pressure (e.g., below 50 mbar) before curing to remove as much water as possible that is introduced with its components, especially when water-stabilized peroxides are used.

[0110] In one embodiment, the polymeric composition has a water content of equal to or less than 0.5 wt% based on the weight of the polymeric composition.

[0111] Polymerizable compositions can be polymerized to a thermosetting state using conventional techniques known for polymerizing formulations containing polyallyl functional monomers.

[0112] In one embodiment, a polymeric composition is placed in a mold (e.g., a glass mold) and polymerized to form a shaped article such as a lens preform or a lens. This process is particularly advantageous for the preparation of ophthalmic lens preforms and ophthalmic lenses.

[0113] According to the present invention, polymerization is accomplished by heating the polymerizable composition according to a curing cycle (i.e., temperature-time sequence) as described below.

[0114] In step B1, the polymerizable composition is heated to an activation temperature T that is 12 to 3 degrees Celsius (°C), preferably 10 to 3 degrees Celsius, and more preferably 8 to 3 degrees Celsius, lower than the 10-hour half-life temperature of the aromatic peroxide. A For example, when BPO is used as an initiator (10-hour half-life temperature equals 73°C), T A You can choose from the range of 61℃ to 70℃, 63℃ to 70℃, or 65℃ to 70℃.

[0115] As described above, a mixture of two or more aromatic peroxides having the same or different 10-hour half-life temperatures can be used when needed. In this case, if the 10-hour half-life temperatures are the same, the activation temperature T is... A The activation temperature is 12 to 3 degrees Celsius lower than the 10-hour half-life temperature, or within the preferred range as described above. If the 10-hour half-life temperatures of the two or more initiators are different, the preferred activation temperature T is... A The temperature is 12 to 3 degrees Celsius lower than the lowest 10-hour half-life temperature of the initiator in the mixture, or within the preferred range described above.

[0116] Typically, the polymeric composition is at ambient temperature when cast into a mold, and the heating device used for polymerization (e.g., an oven) is at an initial temperature of about 35 to 50°C. However, it is not a problem to introduce the mold filled with the polymeric composition into the oven at such a temperature, because such a temperature is much lower than the 10-hour half-life temperature of the aromatic peroxide initiator.

[0117] The curing cycle according to the present invention includes at least a temperature T. A The isothermal step (B2) is then performed. In this step, the polymerizable composition is subjected to a temperature T... A The period during which the product is kept is 8 to 24 hours, preferably 8 to 20 hours, more preferably 8 to 15 hours, and even more preferably 8 to 12 hours.

[0118] If the polymeric composition being cast into the mold is at ambient temperature, it is preferable to slowly heat the mold containing the composition to the activation temperature T, for example, over a period of 1 to 6 hours, more preferably over a period of 1 to 3 hours. A .

[0119] Isothermal heat treatment and possible activation temperature T AThe slow heating rate avoids excessive heat generation within the material range of the polymeric composition caused by rapid activation of the initiator, thus allowing the polymeric composition to gradually gel without significant volume expansion.

[0120] When using temperatures with different 10-hour half-lives (e.g., T... 1-10h <T 2-10h <T 3-10h When a mixture of two or more aromatic peroxides (e.g., <etc.>) is used, it is preferable to use a mixture at a temperature T A1 Perform the first isothermal heat treatment, followed by temperature T A2 Perform a second isothermal heat treatment at temperature T A3 A third isothermal heat treatment is performed, and so on for each of the different further initiators present in the polymerizable composition, wherein T A1 T A2 T A3（…） This is compared to the 10-hour half-life temperature of the corresponding initiator (i.e., T). 1-10h T 2-10h T 3-10h (...)) 12 to 3 degrees Celsius lower, or the temperature value within its preferred range as described above.

[0121] The polymerizable composition at temperature T A (or temperature T) A1 T A2 T A3 …) After isothermal treatment, at the final temperature T F The polymerization is complete at the final temperature T. F Select within the range of 80°C to 120°C, preferably 85°C to 105°C, and more preferably 90°C to 100°C (step B3).

[0122] Temperature T F The choice of T depends on several factors, including the type of ASI selected, its amount in the polymerizable composition, the desired polymerization conversion, the type of polyallyl functional monomer, the duration of isothermal step B2, and the size of the mold. Those skilled in the art can select T based on their ordinary knowledge or through routine experiments. F .

[0123] In one implementation, temperature T F The temperature is equal to or higher than the 1-hour half-life temperature of the initiator, i.e., the temperature at which half of the initially present initiator will decompose within 1 hour. This temperature selection ensures that the residual peroxide is consumed in a short time and achieves complete curing of the polymerization product.

[0124] Temperature T F It is preferable to reach the final temperature T at a slow heating rate.F i.e. the temperature of the polymerizable composition is raised from the activation temperature T A slowly to the final temperature T F . The temperature of the polymerizable composition from T A to T F can be increased stepwise or continuously (i.e. at a constant heating rate). As a general principle, the longer the duration of the isothermal treatment at T A temperature, the faster the temperature ramp from T A to T F .

[0125] In order to obtain a process that can be advantageously employed on an industrial scale, the overall duration of the curing cycle is preferably in the range of 40 to 50 hours.

[0126] The duration of the heat treatment at temperature T F to obtain the optical article (step B4) can vary greatly depending on, for example, the value of T F , the temperature ramp of the previous heat treatment and the temperature and duration differences. Preferably, the polymerizable composition is maintained at temperature T F for a period of 0 to 30 hours, more preferably for a period of 1 to 25 hours, to achieve complete polymerization of the optical article. Complete polymerization of the polymerizable composition is considered to be achieved when the liquid polymerizable composition has been transformed into a solid optical material suitable for demolding.

[0127] After complete polymerization has been achieved, the solid optical material is generally cooled before demolding, preferably in the temperature range of 40 to 80°C, more preferably 50 to 70°C. The cooling rate is not a critical factor. For example, the mold containing the polymerized optical material can be left at ambient temperature outside the heating device.

[0128] The demolded optical material can be subjected to post-curing, i.e. to heating at a temperature at or above the maximum temperature of the curing cycle, but below those at which thermal degradation of the material can occur. The post-curing treatment can allow neutralization of the free radical species of the polymerization initiator that can still be present in the polymerized article, and elimination of possible demolding stresses from the polymerized article.

[0129] When a bleaching agent containing a tetraazaporphyrin (TAP) dye is added to the polymerizable composition to compensate for the yellow color of the polymer article (e.g. caused by the presence of UV absorbing compounds or due to the initiator), post-curing can also be used to increase the efficiency of the TAP dye, as disclosed in WO 2022224928 A1.

[0130] The post-cure treatment can be performed at a temperature ranging from 90°C to 130°C.

[0131] The polymerization of the polymeric composition can be performed in conventional equipment such as a convection oven or a water bath. The mold can be a traditional mold, for example made of two mold pieces and a gasket forming a cavity that defines the shape and dimensions of the final optical material. The mold pieces can be made of glass, metal or plastic.

[0132] The optical material of the application can be used for various applications, in particular ophthalmic lenses, lenses for protective visors, optical filters, etc. An ophthalmic lens is defined herein as a lens designed to fit into an eyeglass frame in order to protect the eye and / or to correct vision. The ophthalmic lens can be a non-corrective ophthalmic lens (also called a plain or afocal lens) or a corrective ophthalmic lens. The corrective lens can be a single vision, bifocal, trifocal or progressive lens.

[0133] The optical material can be coated with one or more functional coatings selected from the group consisting of an anti-abrasion coating, an anti-reflective coating, an anti-fouling coating, an anti-static coating, an anti-fog coating, a polarizing coating, a tinted coating and a photochromic coating.

[0134] The application will now be described in greater detail by way of the following examples, which are given for the purpose of illustration only and are not intended to limit the scope of the application in any way: Examples Characterization methods The optical material is evaluated by means of the following methods.

[0135] Yellowness index (YI) (ASTM D-1925) : The YI is determined on the optical material in the form of a 4 mm plain lens with a Gretag Macbeth 1500 Plus spectrophotometer, taking into account the standard illuminant C and the observer (2° angle). The YI is defined as: YI = 100 / Y (1.277X - 1.06Z).

[0136] Total light transmission and haze values : The total luminous transmission and haze values of the optical material in the form of a flat plate having a thickness of 2 mm are determined according to ASTM D 1003 with a digital haze meter haze-gard plus manufactured by BYK-Gardner.

[0137] Light transmission at specified wavelengths : The transmittance at the specified wavelength of the optical material in the form of a flat plate having a thickness of 2 mm is measured with an ultraviolet-visible spectrophotometer Agilent Cary 60.

[0138] The expressions "UV-cut" and "HEV-cut" as used herein mean the highest wavelength in the UV region (280 nm to 380 nm) and in the HEV region (380 nm to 500 nm) for which the optical material has a transmission lower than 1% measured according to ASTM D 1003.

[0139] Color test for 2 mm flat mirrors : The ability of the material to absorb the dye on its surface was determined by dyeing neutral flat 2 mm lenses in a BPI TM gray solution for 20 minutes at 95°C in a dyeing instrument bath (model COLORADO Electronic from ORGANIZZAZIONE GF). After rinsing with demineralized water, the lenses were measured for total transmission as described above. In addition, the dyed lenses were visually evaluated for homogeneity / heterogeneity by exposure to a backlit viewer (model Professional 20-5000K from LUPO DAYLIGHT).

[0140] Mechanical properties - Rockwell hardness M The Rockwell hardness M (ASTM D-785) of the optical material was evaluated on 5 mm thick flat sheets.

[0141] Materials In the examples, the following compounds were used.

[0142] Polyallyl functional monomers The polyallyl functional monomer was prepared by reacting diallyl carbonate (component A), diethylene glycol as diol (component B) and pentaerythritol as polyol (component C) in a molar ratio A / (B+C) equal to 7.2 and a ratio C / (B+C) equal to 2,29 wt.%.

[0143] The following compounds were charged into a three-necked jacketed flask equipped with a thermometer and a magnetic stirrer, topped with a distillation column with 10 perforated plates of 30 mm diameter: - pentaerythritol (PE): 5 g (0.04 moles); - diethylene glycol (DEG): 213 g (2.01 moles); - diallyl carbonate (DAC): 2100 g (14.80 moles); - 20% by weight solution of sodium methoxide in methanol: 1.0 ml.

[0144] The reaction was carried out at a temperature of 85°C to 120°C and at a reduced pressure of 200 to 130 mbar by distilling off the allyl alcohol (total 242 g (285 ml); purity greater than 99%) during the formation of the allyl alcohol for 3 hours.

[0145] After cooling, the reaction mixture was washed with two aliquots of 500 ml of demineralised water.

[0146] The excess DAC was distilled off at a pressure of about 1 mbar by operating at an elevated temperature of up to 130 C: the product obtained was filtered through a 0.45 m membrane filter.

[0147] 512 g of liquid product were obtained, having the following characteristics: - viscosity (25 C): 17 cSt; - density (20 C): 1.152 g / ml; - refractive index nD20: 1.453; - Apha colour: 1.

[0148] The above polyallyl functional monomers are obtained in the form of mixtures of monomers and oligomers of diethylene glycol bis(allyl carbonate), monomers and oligomers of neopentyl glycol bis(allyl carbonate), monomers and oligomers of tetra(allyl carbonate) of pentaerythritol, and mixed poly(allyl carbonates) of mixtures of the above diols and polyols.

[0149] The amount of diethylene glycol bis(allyl carbonate) compound of formula (II) with n = 1 is about 83% by weight, based on the weight of the mixture of monomers and oligomers. This amount was determined by HPLC analysis of the reaction product at a temperature = 25°C; the sample of the reaction product submitted for analysis was in the form of a 10% by weight solution in acetonitrile; the sample injected = 5 microlitres; eluent: mixture acetonitrile / water (45 / 55% by volume); UV detector.

[0150] UV absorbers - BP6 (2,2'-dihydroxy-4,4'-dimethoxybenzophenone, MFCI).

[0151] - Lowilite 20 by Addivant: 2-dihydroxy-4-methoxybenzophenone.

[0152] Peroxide radical polymerization initiator - Luperox A75 (registered trademark) by ARKEMA; water-stabilised benzoyl peroxide (25% by weight of water), in the form of a granular wet powder.

[0153] - PERKADOX CH50-L by Nouryon; peroxide benzoyl stabilized with phthalate ester (50 wt.% alkyl phthalate ester) in the form of a granular wet powder.

[0154] - Trigonox ADC-NS30 (registered trademark) by NOURYON; this commercial product contains about 70% by weight of diethylene glycol bis(allyl carbonate) and 30% by weight of a mixture of isopropyl peroxydicarbonate, sec-butyl and isopropyl / sec-butyl peroxydicarbonate.

[0155] TAP dyes (bleach) As bleaching agent is the commercial product FDG-005 (Pd-containing TAP compound with main absorption peak at 583 nm) by Yamada Chemicals. The product FDG-005 is used in the form of a masterbatch, i.e. pre-dispersed in a multi-allyl functional monomer at a concentration of 0.05 wt. based on the weight of the monomer.

[0156] UV & Blue cut MB TM (bleach) Bleaching masterbatch based on a proprietary composition of pigments dispersed in a multi-allyl functional monomer provided by Acomon SRL (about 2.0 wt.% of pigments in the multi-allyl functional monomer based on the weight of the monomer).

[0157] Example 1 (Samples 1 to 4) Liquid polymeric compositions were prepared by mixing 100 parts by weight (pbw) of multi-allyl functional monomer with BPO initiator, or with IPP initiator and additives in the ratios reported in Table 5 for comparison purposes.

[0158] Before casting, each polymeric composition was mixed vigorously with a magnetic stirrer, degassed for 3 hours at a pressure below 50 mbar and then filtered on a PTFE membrane of 0.45 microns (47 mm diameter).

[0159] To determine the total transmittance and the haze %, the polymeric compositions were cast in glass molds in the form of flat mirrors with a thickness of 2 mm and polymerized, and to determine the YI and the Rockwell hardness, the polymeric compositions were cast in glass molds in the form of flat mirrors with a thickness of 5 mm and polymerized. The Rockwell hardness was also determined on flat mirrors of 10 mm thickness.

[0160] The polymerization was completed by heating the molds containing the polymeric composition in a forced air circulation oven following one of the curing cycles reported in Tables 1 to 4. The polymeric composition was cast at ambient temperature (25°C) and introduced into the oven set at the initial temperature reported in Tables 1 to 4.

[0161] At the end of the curing cycle, the mould is removed from the oven and allowed to cool to ambient temperature. The polymeric article is then post-cured at a temperature of 110-130°C for 1-2 hours in a forced air circulation oven, as described below.

[0162] The process yield is evaluated by determining the ratio of the number of articles exhibiting defects (i.e. cracks or flow lines) relative to the total number of articles cast.

[0163] The optical and mechanical properties of the polymeric materials are reported in Table 5.

[0164] The polymeric optical article has a UV cut-off at 355 nm.

[0165] The data of Table 5 show that the use of BPO according to the process of the application (sample 3) enables to obtain optical articles having good mechanical and optical properties, which are comparable to those of the articles obtained from the IPP polymerized composition (sample 4). The yield of the process is also very high.

[0166] On the contrary, the use of BPO in higher amounts or by shorter curing cycles (samples 1 and 2) have a detrimental effect on the lens quality in addition to a decrease in the casting yield. The lenses obtained with comparative sample 1 have a too high yellowness index and hardness, which is mainly due to the high ASI content. The too high hardness is very likely to induce cracks during the curing and / or demoulding steps, especially for thick lenses. On the contrary, the lenses obtained according to comparative sample 2 have several features of optical defects, such as flow lines and streaks, especially when thick semi-finished lenses are prepared. This is mainly due to the too short curing cycle and the ASI reactivity.

[0167] The difference in curing conditions and the low initiator dose in comparative sample 2 are also reflected in the colouring behaviour, wherein samples can be considered as having similar colour shades in practice when the difference in total T% value is within + / - 5 units.

[0168] The lenses obtained according to the curing cycle 1 of the application show a T% and a good homogeneity similar to those of the same composition cured with the conventional IPP curing cycle 4 (reference). On the other hand, comparative samples 1 and 2 are either too hard or too soft, have a colour shade deviation or an undesirable inhomogeneity of dye absorption, relative to the lenses obtained with the reference (where IPP is used and curing cycle 4 is applied).

[0169] Example 2 - Samples 5 to 10 The polymeric compositions of samples 5 to 10 were prepared as described in example 1, except that a bleaching agent was additionally included in the polymeric composition. In the case of a pigment-based bleaching agent, a final filtration of the polymeric composition was performed on a depth filter with a maximum pore size of 5 microns.

[0170] The compositions tested and their optical and mechanical properties are reported in table 6.

[0171] The data of table 6 show the optical and mechanical properties of the lenses obtained with the conventional IPP curing cycle and the inventive curing cycle at different cut ratios (obtained by addition of UV absorbers).

[0172] Due to the low initiator dose and the high efficient polymer conversion, lenses with very similar properties to those of IPP cured lenses (reference) were obtained using the inventive process. Moreover, the tinting behavior, closely related to the good conversion of the final polymerization product, was very similar for BPO cured and IPP cured materials.

Claims

1. A method for manufacturing polymer optical articles, the method comprising: A. Providing a polymerizable composition, said polymerizable composition comprising: - At least one polyallyl functional monomer having formula (I): Where X represents a divalent to hexavalent group derived from a linear or branched aliphatic polyol having 3 to 12 carbon atoms, or a divalent to hexavalent group derived from an alicyclic polyol having 5 to 16 carbon atoms, and n represents an integer from 2 to 6. The polyallyl functional monomer having formula (I) comprises 70 wt.% or more, preferably 80 wt.% or more of n equal to 2 polyallyl functional monomers having formula (I), the weight percentage being based on the total weight of the polyallyl functional monomers having formula (I). - 0.5 to 2 wt.% of at least one aromatic peroxide as a free radical initiator, the weight percentage being based on the total weight of the polyallyl functional monomer; B. Curing the polymeric composition according to a curing cycle, the curing cycle including: B1. Heating the polymeric composition to an activation temperature T that is 12°C to 3°C lower than the 10-hour half-life temperature of the aromatic peroxide. A ; B2. The polymeric composition is subjected to temperature T. A Maintain for 8 to 24 hours; B3. After step B2, heat the polymeric composition to a final temperature T in the range of 80°C to 120°C. F ; B4. Maintain the polymerizable composition at the final temperature T. F To obtain optical items.

2. The method according to claim 1, wherein, In step B1, the polymerizable composition is heated to an activation temperature T that is 10°C to 3°C lower than the 10-hour half-life temperature of the aromatic peroxide. A .

3. The method according to claim 1 or 2, wherein, In step B2, the polymerizable composition is activated at temperature T. A The period during which it is kept is 8 to 20 hours, preferably 8 to 15 hours, and more preferably 8 to 12 hours.

4. The method according to any one of claims 1 to 3, wherein, In step B3, the polymeric composition is heated to a final temperature T in the range of 85°C to 105°C, preferably 90°C to 100°C. F .

5. The method according to any one of claims 1 to 4, wherein, In step B3, the polymeric composition is heated to a final temperature T over a period of 5 to 40 hours, preferably 15 to 40 hours, more preferably 18 to 40 hours, even more preferably 20 to 35 hours, and even more preferably 22 to 30 hours. F .

6. The method according to any one of claims 1 to 5, wherein, In step B4, the polymerizable composition is subjected to a final temperature T. F The period is maintained for 0 to 30 hours, preferably 1 to 25 hours.

7. The method according to any one of claims 1 to 6, wherein, The polymeric composition does not contain olefinic unsaturated compounds that are different from the polyallyl functional monomer having formula (I).

8. The method according to any one of claims 1 to 7, wherein, At least one of the polyallyl functional monomers has a kinematic viscosity at 25°C in the range of 10 to 300 cSt, preferably 10 to 100 cSt, and more preferably 10 to 40 cSt.

9. The method according to any one of claims 1 to 8, wherein, The polyallyl functional monomer is a diethylene glycol bis(allyl carbonate) compound of formula (II): Where n is an integer equal to or greater than 1 and equal to or less than 10; The diethylene glycol bis(allyl carbonate) compound of general formula (II) comprises 70 wt.% or more, preferably 80 wt.% or more of the diethylene glycol bis(allyl carbonate) compound of formula (II) with n equal to 1, the weight percentage being based on the total weight of the diethylene glycol bis(allyl carbonate) compound of general formula (II).

10. The method according to claim 9, wherein, The polymeric composition does not contain olefinically unsaturated compounds that are different from the diethylene glycol bis(allyl carbonate) compound having formula (II).

11. The method according to any one of claims 1 to 10, wherein, At least one of the polyallyl functional monomers comprises a reaction product (RP) containing: diallyl carbonate (A); one or more linear or branched aliphatic diols (B) having 3 to 10 carbon atoms in the molecule; and optionally, a linear or branched aliphatic polyol (C) having 4 to 20 carbon atoms and 3 to 6 hydroxyl groups in the molecule; wherein the molar ratio A / (B+C) is in the range of 4 / 1 to 20 / 1, and the amount of the optional component (C) in the mixture (B+C) is equal to or less than 5 wt.%, preferably equal to or less than 3 wt.%, relative to the total weight of the mixture (B+C).

12. The method according to any one of claims 1 to 10, wherein, At least one of the polyallyl functional monomers comprises a reaction product (RP) containing the following components: diallyl carbonate (A); one or more linear or branched aliphatic diols (B) containing 3 to 10 carbon atoms in a molecule; and linear or branched aliphatic polyols (C) containing 4 to 20 carbon atoms and 3 to 6 hydroxyl groups in a molecule; wherein the molar ratio A / (B+C) is in the range of 4 / 1 to 20 / 1, preferably 5 / 1 to 15 / 1, and the amount of component (C) in the mixture (B+C) is equal to or less than 5 wt.%, preferably equal to or less than 3 wt.%, relative to the total weight of the mixture (B+C).

13. The method according to any one of claims 1 to 12, wherein, The aromatic peroxide is benzoyl peroxide.

14. The method according to any one of claims 1 to 13, wherein, In step A, at least one of the polyallyl functional monomers is mixed with water-stabilized benzoyl peroxide.

15. The method according to claim 14, wherein, The water-stabilized benzoyl peroxide contains an amount of water equal to or less than 50 wt.%, preferably equal to or less than 25 wt.%, based on the total weight of the water-stabilized benzoyl peroxide.

16. A polymer optical article obtained by the method according to any one of claims 1 to 15.

17. An ophthalmic lens comprising the polymer optical article of claim 16.

18. A polymerizable composition comprising: - Polyallyl functional monomers of formula (I): in, X represents a divalent to hexavalent group derived from a linear or branched aliphatic polyol having 3 to 12 carbon atoms, or a divalent to hexavalent group derived from an alicyclic polyol having 5 to 16 carbon atoms, and n represents an integer from 2 to 6. The polyallyl functional monomer having formula (I) comprises 70 wt.% or more, preferably 80 wt.% or more of n equal to 2 polyallyl functional monomers having formula (I), the weight percentage being based on the total weight of the polyallyl functional monomers having formula (I). - 0.5 to 2 wt.% of at least one aromatic peroxide as a free radical initiator, preferably benzoyl peroxide, the weight percentage being based on the total weight of the polyallyl functional monomer.

19. The polymerizable composition according to claim 18, wherein, The polymeric composition does not contain olefinic unsaturated compounds that are different from the polyallyl functional monomer having formula (I).

20. The polymerizable composition according to claim 18, wherein, The polyallyl functional monomer is a diethylene glycol bis(allyl carbonate) compound of formula (II): Where n is an integer equal to or greater than 1 and equal to or less than 10; The diethylene glycol bis(allyl carbonate) compound of general formula (II) comprises 70 wt.% or more, preferably 80 wt.% or more of the diethylene glycol bis(allyl carbonate) compound of formula (II) with n equal to 1, the weight percentage being based on the total weight of the diethylene glycol bis(allyl carbonate) compound of general formula (II).

21. The polymerizable composition according to claim 20, wherein, The polymeric composition does not contain olefinically unsaturated compounds that are different from the diethylene glycol bis(allyl carbonate) compound having formula (II).

Images