HK1053481B

HK1053481B - Method of preparing an optical polymerizate

Info

Publication number: HK1053481B
Application number: HK03105823.9A
Authority: HK
Inventors: M‧O‧俄克劳弗; R‧A‧史密斯; M‧J‧格拉汉姆; R‧塔巴科维克; R‧D‧海洛尔德
Original assignee: Ppg工业俄亥俄公司
Priority date: 1999-11-18
Filing date: 2000-11-18
Publication date: 2010-09-03

Description

Process for producing optical polymer

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from USSN 60/166184 entitled "method for producing optical polymers" filed on 11/18/1999.

Background

1. Field of the invention

The invention relates to a method for producing polymers from a two-component organic composition, said polymers having a refractive index of at least 1.6, an Abbe number of at least 33 and an initial Babbitt hardness of at least 1. More particularly, the present invention relates to polymerizing certain two-part organic compositions comprising at least one polycyanate reactant having at least two isocyanate and/or isothiocyanate groups and a polyamine having at least two primary and/or secondary amine groups. The invention also relates to polymers and photochromic articles.

2. Description of the Prior Art

Many organic polymeric materials, such as plastics, have been developed as glass substitutes in applications such as optical lenses, fiber optics, windows and automotive, marine and aerospace transparencies. The term "glass" as used herein means silica-based inorganic glass. These polymeric materials may provide several advantages over glass, including shatter resistance, lighter weight for a given application, ease of molding, and ease of dyeing. Typical examples of such polymeric materials include polymethyl methacrylate, thermoplastic polycarbonate and poly (allyl carbonate) diethylene glycol.

In general, many polymeric materials have a refractive index lower than that of glass. For example, the refractive index of the polydiallyl diglycol ester of poly (allyl carbonate) is about 1.50, while the refractive index of the high index glass may be in the range of, for example, 1.60 to 1.80. In forming lenses to correct a given degree of visual impairment, for example to correct myopia, a thicker lens will be required with a polymeric material having a lower refractive index than a material having a higher refractive index, for example high index glass. If the degree of correction required is large, for example in the case of severe myopia, lenses made from low index polymer materials may need to be thick. A very thick lens may negate any benefit of using a low density lens material relative to an equivalent degree of correction obtained from a glass lens with a higher refractive index. Furthermore, thicker optical lenses are also less desirable from an aesthetic point of view.

It is known that polymeric materials having a refractive index greater than 1.50 can be prepared from aromatic monomers containing halogen and/or sulfur atoms. The materials from which the lenses, particularly optical lenses, are made can be classified according to their refractive index. As known to those of ordinary skill in the art, low indices typically include refractive indices below 1.50 to 1.53; medium indices include refractive indices of 1.54 to 1.57; high indices typically include refractive indices of 1.58 and greater. Lenses made of high refractive index polymeric materials typically also have a lower abbe number (also referred to as v-number). A low abbe number indicates an increase in the dispersion, typically manifested as optical distortion at or near the edge of the lens.

US5961889(Jiang et al) discloses optical polymers for ophthalmic lenses prepared from polythiol group-containing components, polyisocyanate group-containing components and/or polyfunctional vinyl group-containing components. The disclosed polymers typically have a refractive index of less than 1.69 and an Abbe number of less than 35.

US5932681(Herold et al) discloses an optical polymer useful as a lens material, prepared from isocyanates or isothiocyanates and polythiols. The disclosed polymers have a refractive index of at least 1.57 and an Abbe number of at least 33.

U.S. Pat. No. 5,5679756 (Zhu et al) discloses an optical polymer, known as a thermoplastic thiocarbamate-urethane copolymer, prepared by reacting an aliphatic diisocyanate with a dithiol to form a thiocarbamate prepolymer, which is then reacted with a diisocyanate and a polyol. The disclosed polymers typically have a refractive index between 1.57 and 1.60 and an abbe number between 35 and 38.

Although the above optical polymers have sufficient refractive index and dispersion, they do not necessarily have impact resistance suitable for use as required for daily wearing spectacle lenses.

It would therefore be desirable to find new polymeric materials, such as polymers, useful for the preparation of transparent polymers, in particular optical lenses, having a high refractive index and a sufficiently high abbe number, and also having physical properties, in particular impact resistance, at least equal to, preferably better than, polymeric materials having a lower index.

Summary of The Invention

The present invention provides a method of preparing a polymer comprising the step of polymerizing a two-part composition comprising:

(a) a first component comprising at least one polycyanate reactant having at least two functional groups selected from the group consisting of isocyanate, isothiocyanate and combinations thereof, the polycyanate reactant being the reaction product of:

(i) a polythiol monomer having at least two thiol groups; and

(ii) a polycyanate monomer having at least two functional groups selected from isocyanate, isothiocyanate and combinations thereof; and

(b) a second component comprising at least one polyamine reactant having at least two functional groups selected from the group consisting of primary amines, secondary amines, and combinations thereof.

The invention also relates to polymers prepared by the process of the invention.

The present invention also relates to photochromic articles that can be prepared from the polymers of the present invention.

Detailed Description

Unless otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, and the like used herein are to be understood as modified by the term "about.

(i) a polythiol monomer having at least two thiol groups;

(iii) optionally an active hydrogen material having at least two active hydrogen groups selected from polyols, hydroxyl and thiol containing materials and mixtures thereof, the relative amounts of (i), (ii) and (iii) being selected such that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is greater than 1.0; and

(b) a second component comprising at least one polyamine reactant having at least two functional groups selected from the group consisting of primary amines, secondary amines, and combinations thereof. The first and second components are selected such that they, when polymerized, produce a polymer having a refractive index of at least 1.6 (e.g., 1.60 to 1.74), an Abbe number of at least 33, and an initial Babbitt hardness of at least 1. The refractive index is measured according to the American Standard Test Method (ASTM) D542-95. The Abbe or v-value is measured with a suitable instrument such as a Bausch & Lomb ABBE-3L refractometer. The initial Babbitt hardness (also commonly referred to as zero second Babbitt hardness) is measured according to ASTM No. D2583-95.

The polycyanate reactant of the first component of the two-component composition has at least two functional groups selected from the group consisting of isocyanato (-NCO), isothiocyanato (-NCS), and combinations thereof. The term "cyanato" as used herein means unblocked (or unblocked) isocyanato and isothiocyanato groups capable of forming covalent bonds with active hydrogen groups such as thiol, hydroxyl or amine groups.

The polycyanate reactant is the reaction product of a polythiol monomer, a polycyanate monomer, and optionally an active hydrogen source such as a polyol or a material having hydroxyl and thiol groups. The relative amounts of polythiol monomer, polycyanate monomer, and optional active hydrogen starting material in preparing the polycyanate reactant are selected such that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is greater than 1.0, for example, from 1.2: 1.0 to 4.0: 1.0 or from 2.0: 1.0 to 3.0: 1.0.

The polycyanate reactant of the first component of the two-part composition has a backbone selected from the group consisting of a urethane chain (-NH-C (O) -O-), a thiocarbamate chain (-NH-C (O) -S-), a thiocarbamate chain (-NH-C (S) -O-), a dithiocarbamate chain (-NH-C (S) -S-), and combinations thereof. The molecular weight of the polycyanate reactant can vary over a wide range, for example, from 500 to 15000, or from 500 to 5000 number average molecular weight (Mn) as measured by Gel Permeation Chromatography (GPC) using polystyrene standards.

The polythiol monomer used to prepare the polycyanate reactant has at least two thiol groups and can be selected from the group consisting of aliphatic polythiols, cycloaliphatic polythiols, aromatic polythiols, and mixtures thereof. Furthermore, the polythiol monomer may further comprise a monomer selected from the group consisting of an ether chain (-O-), a sulfur chain (-S-), and a polythiol chain (-S-)_xWhere x is at least 2, for example 2 to 4) and combinations of these chains. As used herein, thiol "or" mercapto "means an-SH group capable of forming a thiourethane chain (i.e., -NH-C (O) -S-) with an isocyanate group or a dithiourethane chain (i.e., -NH-C (S) -S-) with an isothiocyanate group.

Examples of polythiol monomers that can be used to prepare the polycyanate reactant include, but are not limited to, 2, 5-dimercaptomethyl-1, 4-dithiane, 2 '-thiodiethanethiol, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (2-mercaptoacetate), 4-mercaptomethyl-3, 6-dithio-1, 8-octanedithiol, 4-tert-butyl-1, 2-benzenedithiol, 4' -thiodiphenylthiol, benzenedithiol, ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (2-mercaptoacetate), Polyethylene glycol bis (3-mercaptopropionate). Mixtures of polythiol monomers can also be used to prepare the polycyanate reactants.

The polythiol monomer can also be selected from polythiols represented by the following general formula I:

wherein R is₁And R₂Independently selected from the group consisting of straight or branched chain alkylene, cycloalkylene, phenylene and C₁-C₉Alkyl-substituted phenylene radicals. R₁And R₂Examples of alternative straight or branched chain alkylene groups include, but are not limited to, methylene, ethylene, 1, 3-propylene, 1, 2-propylene, 1, 4-butylene, 1, 2-butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, octadecylene and eicosylene. R₁And R₂Examples of alternative cycloalkylene groups include, but are not limited to, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, and alkyl-substituted derivatives thereof. Divalent linking group R₁And R₂And may also be selected from phenylene and alkyl-substituted phenylene, such as methyl-, ethyl-, propyl-, isopropyl-and nonyl-substituted phenylene. In a preferred embodiment of the invention, R₁And R₂Each methylene or ethylene.

Polythiols of formula I can be prepared by esterification or transesterification of 3-mercapto-1, 2-propanediol (Chemical AbstractServices (CAS) Registry No.96-27-5) and a mercapto-functional carboxylic acid or ester in the presence of a strong acid catalyst such as methanesulfonic acid while removing water or alcohol from the reaction mixture. More particularly, preferred polythiol monomers are R in formula I₁And R₂Polythiol monomers which are all methylene groups.

Polythiol monomers such as thioglycerol di (2-mercaptoacetate), as described and named according to formula I, are used herein to mean a polythiol monomer composition that also includes any associated co-produced oligomers and contains the remaining raw materials. For example, oxidative coupling of the thiol group may occur when the reaction mixture obtained by esterification of 3-mercapto-1, 2-propanediol and a thiol-functional carboxylic acid, such as 2-mercaptoacetic acid, is washed with an excess of a base, such as aqueous ammonia. This oxidative coupling may result in polythiol oligomers having disulfide chains, i.e., -S-chains.

The polythiol monomer used to prepare the polycyanate reactant can be a polythiol oligomer having disulfide linkages, prepared by reacting a polythiol monomer having at least two thiol groups with sulfur in the presence of a basic catalyst. The molar equivalent ratio of polythiol monomer to sulfur is m to (m-1), wherein m is an integer from 2 to 21. The polythiol monomer can be selected from those examples previously described, such as 2, 5-dimercaptomethyl-1, 4-dithiane. The sulphur used may be, for example, in the form of crystalline, colloidal, powder and sublimed sulphur, having a purity of at least 98%, preferably at least 99%.

The co-produced oligomers may include oligomers of formula I, which may be described by formula Ia:

wherein R is₁And R₂As previously defined, n and m are independently integers from 0 to 21, and n + m is at least 1. Formula Ia demonstrates that oligomerization can occur through the disulfide bond formed between any thiol groups in general structure I. While not all possibilities are shown, generic structure Ia is meant to represent all possible oligomers that can be formed from generic structure I.

The basic catalyst used to prepare polythiol oligomers having disulfide linkages can be selected from the group consisting of ammonia, amines, and mixtures thereof. Examples of amines include, but are not limited to, alkylamines such as ethylamine and n-butylamine, dialkylamines such as diethylamine, trialkylamines such as triethylamine, morpholine, substituted morpholines, piperidine, and substituted piperidines. The basic catalyst is typically present in an amount of from 0.001 to 1.0 mole percent, for example from 0.01 to 0.1 mole percent, based on the moles of polythiol monomer present at the beginning of the reaction. The basic catalyst may be charged into the reaction vessel together with the polythiol monomer and sulfur, or may be added to the reaction vessel after the polythiol monomer and sulfur are added.

The synthesis of polythiol oligomers having disulfide chains can be carried out in the presence of a solvent, for example, a halogenated hydrocarbon such as chloroform, an aliphatic hydrocarbon such as hexane, an aromatic hydrocarbon such as toluene, and an ether such as tetrahydrofuran. The polythiol oligomer can be prepared at a temperature ranging from room temperature to the boiling point of the solvent, e.g., from room temperature to 120 ℃. The preparation of polythiol oligomers having disulfide linkages suitable for use in the present invention is described in more detail in US5961889, the contents of which are incorporated herein by reference.

In one embodiment of the invention, the polythiol oligomer having disulfide linkages can be selected from those represented by the following formula II:

wherein n is an integer from 1 to 21. Polythiol oligomers of formula II can be prepared by reacting 2, 5-dimercaptomethyl-1, 4-dithiane with sulfur in the presence of a basic catalyst (as described above).

The polycyanate monomer (a) (ii) used to prepare the polycyanate reactant of first component (a) can be selected from the group consisting of polyisocyanates having at least two isocyanate groups, isothiocyanates having at least two isothiocyanate groups, and polycyanates having both isocyanate and isothiocyanate groups. The types of polyisocyanates that can be selected for the polycyanate monomer (a) (ii) include, but are not limited to: an aliphatic polyisocyanate; an ethylenically unsaturated polyisocyanate; an alicyclic polyisocyanate; aromatic polyisocyanates in which the isocyanate groups are not directly bonded to the aromatic ring such as α, α' -xylene diisocyanate; aromatic polyisocyanates such as phenylene diisocyanate in which the isocyanate groups are directly bonded to aromatic rings; an aliphatic polyisocyanate containing a sulfur chain; aromatic polyisocyanates containing sulfur or disulfide chains; an aromatic polyisocyanate containing sulfone chains; sulfonate type polyisocyanates such as 4-methyl-3-isocyanatobenzenesulfonyl-4' -isocyanato-phenol ester; aromatic sulfonamide type polyisocyanates; sulfur-containing heterocyclic polyisocyanates such as thiophene-2, 5-diisocyanate; halogenated, alkylated, alkoxylated, nitrated, carbodiimide-modified, urea-modified and biuret-modified derivatives of these polyisocyanates; and the dimeric and trimeric polymers of these polyisocyanates. Particularly preferred are aliphatic polycyanate monomers containing sulfur chains and other polycyanate monomers having one or more sulfur atoms in the main chain of the monomer. Particularly preferred sulfur-containing polycyanate monomers are of one of the general formulae (III):

wherein R is₁₀And R₁₁Independently is C₁-C₃An alkyl group.

Examples of aliphatic polyisocyanates which may be selected for the polyisocyanate monomer (a) (ii) include, but are not limited to, ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, 2' -dimethylpentane diisocyanate, 2, 4-trimethylhexane diisocyanate, decamethylene diisocyanate, 2, 4, 4-trimethylhexamethylene diisocyanate, 1, 6, 11-undecane triisocyanate, 1, 3, 6-hexamethylene triisocyanate, 1, 8-diisocyanato-4- (isocyanatomethyl) octane, 2, 5, 7-trimethyl-1, 8-diisocyanato-5- (isocyanatomethyl) octane, bis (ethyl isocyanate) carbonate, bis (ethyl isocyanate) ether, 2-isocyanatohexanoic acid 2-isocyanatopropyl ester, lysine diisocyanate methyl ester and lysine triisocyanato methyl ester.

Examples of ethylenically unsaturated polyisocyanates include, but are not limited to, butene diisocyanate and 1, 3-butadiene-1, 4-diisocyanate. The optional cycloaliphatic polyisocyanate of the polyisocyanate monomer (a) (ii) includes, but is not limited to, isophorone diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, bis (isocyanatomethyl) cyclohexane, bis (isocyanatocyclohexyl) methane, bis (isocyanatocyclohexyl) -2, 2-propane, bis (isocyanatocyclohexyl) 1, 2-ethane, 2-isocyanatomethyl-3- (3-isocyanatopropyl) -5-isocyanatomethyl-bicyclo [2.2.1] heptane, 2-isocyanatomethyl-3- (3-isocyanatopropyl) -6-isocyanatomethyl-bicyclo [2.2.1] heptane, 2-isocyanatomethyl-2- (3-isocyanatopropyl) -5-isocyanatomethyl-bicyclo [2.2.1] heptane, and mixtures thereof, 2-isocyanatomethyl-2- (3-isocyanatopropyl) -6-isocyanatomethyl-bicyclo [2.2.1] heptane, 2-isocyanatomethyl-3- (3-isocyanatopropyl) -6- (2-isocyanatoethyl) -bicyclo [2.2.1] heptane, 2-isocyanatomethyl-2- (3-isocyanatopropyl) -5- (2-isocyanatoethyl) -bicyclo [2.2.1] heptane and 2-isocyanatomethyl-2- (3-isocyanatopropyl) -6- (2-isocyanatoethyl) -bicyclo [2.2.1] heptane.

Examples of the aromatic polyisocyanate in which the isocyanate group is not directly bonded to the aromatic ring include, but are not limited to, di (isocyanatoethyl) benzene, α, α, α ', α' -tetramethylxylene diisocyanate, 1, 3-di (1-isocyanato-1-methylethyl) benzene, di (isocyanatobutyl) benzene, di (isocyanatomethyl) naphthalene, di (isocyanatomethyl) diphenyl ether, di (isocyanatoethyl) phthalate, 1, 3, 5-trimethylbenzene triisocyanate and 2, 5-di (isocyanatomethyl) furan. Examples of the aromatic polyisocyanate in which the polyisocyanate monomer (a) (ii) may be selected from isocyanate groups directly bonded to the aromatic ring include, but are not limited to, phenylene diisocyanate, ethylphenylene diisocyanate, isopropylphenylene diisocyanate, dimethylphenylene diisocyanate, diethylphenylene diisocyanate, diisopropylphenylene diisocyanate, trimethylbenzene triisocyanate, benzene triisocyanate, naphthalene diisocyanate, methylnaphthalene diisocyanate, biphenyl diisocyanate, o-toluidine diisocyanate, o-benzylene diisocyanate, 4 ' -diphenylmethane diisocyanate, bis (3-methyl-4-isocyanatophenyl) methane, bis (isocyanatophenyl) ethylene, 3 ' -dimethoxy-biphenyl-4, 4 ' -diisocyanate, mixtures thereof, and the like, Triphenylmethane triisocyanate, polymeric 4, 4 ' -diphenylmethane diisocyanate, naphthalene triisocyanate, diphenylmethane-2, 4, 4 ' -triisocyanate, 4-methyldiphenylmethane-3, 5, 2 ', 4 ', 6 ' -pentaisocyanate, diphenylether diisocyanate, bis (isocyanatophenyl ether) ethylene glycol, bis (isocyanatophenyl ether) -1, 3-propanediol, benzophenone diisocyanate, carbazole diisocyanate, ethylcarbazole diisocyanate, and dichlorocarbazole diisocyanate.

The polyisocyanate monomer (a) (ii) optional sulfur-chain containing aliphatic polyisocyanates include, but are not limited to, thiodiethyl diisocyanate, thiodipropyl diisocyanate, dithiodihexyl diisocyanate, dimethylsulfone diisocyanate, dithiodimethyl diisocyanate, dithiodiethyl diisocyanate, dithiodipropyl diisocyanate, and dicyclohexylsulfide-4, 4' -diisocyanate. Examples of sulfur or disulfide chain containing aromatic polyisocyanates include, but are not limited to, diphenyl sulfide-2, 4 ' -diisocyanate, diphenyl sulfide-4, 4 ' -diisocyanate, 3 ' -dimethoxy-4, 4 ' -diisocyanatodibenzyl sulfide, bis (4-isocyanatomethylbenzene) -sulfide, diphenyl disulfide-4, 4 ' -diisocyanate, 2 ' -dimethyldiphenyl disulfide-5, 5 ' -diisocyanate, 3 ' -dimethyldiphenyl disulfide-6, 6 ' -diisocyanate, 4 ' -dimethyldiphenyl disulfide-5, 5 ' -diisocyanate, 3, 3 '-dimethoxydiphenyl disulfide-4, 4' -diisocyanate, and 4, 4 '-dimethoxydiphenyl disulfide-3, 3' -diisocyanate.

The aromatic polyisocyanate containing sulfone chain which may be selected from the polycyanate monomer (a) (ii) includes, but is not limited to, diphenylsulfone-4, 4 ' -diisocyanate, diphenylsulfone-3, 3 ' -diisocyanate, benzidine sulfone-4, 4 ' -diisocyanate, diphenylsulfone-4, 4 ' -diisocyanate, 4-methyldibenzenesulfone-2, 4 ' -diisocyanate, 4 ' -dimethoxydiphenylsulfone-3, 3 ' -diisocyanate, 3 ' -dimethoxy-4, 4 ' -diisocyanatodibenzylsulfone, 4 ' -dimethyldiphenylsulfone-3, 3 ' -diisocyanate, 4 ' -di-tert-butyldiphenylsulfone-3, 3 ' -diisocyanate, and 4, 4 '-dichlorodiphenyl sulfone-3, 3' -diisocyanate.

Examples of aromatic sulfonamide type polyisocyanates that can be used to prepare the polycyanate reactant include, but are not limited to, 4-methyl-3-isocyanato-benzenesulfonanilide-3 '-methyl-4' -isocyanate, diphenylsulfonoethylenediamine-4, 4 '-diisocyanate, 4' -methoxybenzenesulfonyl-ethylenediamine-3, 3 '-diisocyanate, and 4-methyl-3-isocyanato-benzenesulfonanilide-4-ethyl-3' -isocyanate.

The types of polyisothiocyanates that can be selected for the polycyanate monomer (a) (ii) include, but are not limited to: aliphatic polyisothiocyanates; alicyclic polyisothiocyanates such as cyclohexane diisothiocyanate; aromatic polyisothiocyanates such as α, α' -xylene diisothiocyanate in which the isothiocyanato group is not directly bonded to an aromatic ring; aromatic polyisothiocyanates such as phenylene diisothiocyanate wherein the isothiocyanato group is bonded directly to an aromatic ring; heterocyclic polyisothiocyanates such as 2, 4, 6-triisothiocyanate-1, 3, 5-triazine and thiophene-2, 5-diisothiocyanate; carbonyl polyisothiocyanates; aliphatic polyisothiocyanates containing sulfur chains such as thiobis (3-isothiocyanatopropane); an aromatic polyisothiocyanate containing a sulfur atom other than that of the isothiocyanate group; halogenated, alkylated, alkoxylated, nitrated, carbodiimide-modified, urea-modified and biuret-modified derivatives of these polyisothiocyanates; and the dimeric and trimeric polymers of these polyisocyanates.

Examples of aliphatic polyisothiocyanates from which the polycyanate monomer (a) (ii) may be selected include, but are not limited to, 1, 2-diisothiocyanatoethane, 1, 3-diisothiocyanatopropane, 1, 4-diisothiocyanatobutane and 1, 6-diisothiocyanatohexane. Examples of the aromatic polyisothiocyanate having an isothiocyanate group directly bonded to the aromatic ring include, but are not limited to, 1, 2-diisothiocyanatobenzene, 1, 3-diisothiocyanatobenzene, 1, 4-diisothiocyanatobenzene, 2, 4-diisothiocyanatotoluene, 2, 5-diisothiocyanatom-xylene, 4 ' -diisothiocyanato-1, 1 ' -biphenyl, 1 ' -methylenebis (4-isothiocyanatobenzene), 1 ' -methylenebis (4-isothiocyanato-2-methylbenzene), 1 ' -methylenebis (4-isothiocyanato-3-methylbenzene), 1 ' - (1, 2-ethanediyl) bis (4-isothiocyanatobenzene), 4 ' -diisothiocyanatobenzophenone, and mixtures thereof, 4, 4 ' -diisothiocyanato-3, 3 ' -dimethylbenzophenone, benzanilide-3, 4 ' -diisothiocyanate, diphenyl ether-4, 4 ' -diisothiocyanate and diphenylamine-4, 4 ' -diisothiocyanate.

Carbonyl polyisothiocyanates that can be used to prepare the polycyanate reactant of the first component of the two-component composition include, but are not limited to, adipoyl diisothiocyanate, azelaiyl diisothiocyanate, carbonic acid diisothiocyanate, 1, 3-benzenedicarbonyl diisothiocyanate, 1, 4-benzenedicarbonyl diisothiocyanate, and (2, 2 '-bipyridine) -4, 4' -dicarbonyl diisothiocyanate. Examples of aromatic polyisothiocyanates containing a sulfur atom other than the sulfur of an isothiocyanato group that can be used in the present invention include, but are not limited to, 1-isothiocyanato-4- [ (2-isothiocyanato) sulfonyl ] benzene, thiobis (4-isothiocyanatobenzene), sulfonylbis (4-isothiocyanatobenzene), sulfinylbis (4-isothiocyanatobenzene), dithiobis (4-isothiocyanatobenzene), 4-isothiocyanato-1- [ (4-isothiocyanatophenyl) -sulfonyl ] -2-methoxybenzene, 4-methyl-3-isothiocyanatobenzene-sulfonyl-4 ' -isothiocyanatophenyl ester and 4-methyl-3-isothiocyanatobenzene-sulfonanilide-3 ' -methyl-4 ' -isothiocyanate.

The polycyanate monomer (a) (ii) used to prepare the polycyanate reactant of the first component of the two-component composition can also be selected from polycyanate monomers having both isocyanate and isothiocyanate groups, and can be, for example, aliphatic, cycloaliphatic, aromatic, heterocyclic, or those containing a sulfur atom other than the sulfur of the isothiocyanate group. Examples of such compounds include, but are not limited to, 1-isocyanato-3-isothiocyanatopropane, 1-isocyanato-5-isothiocyanatopentane, 1-isocyanato-6-isothiocyanatohexane, isocyanatocarbonyl isothiocyanate, 1-isocyanato-4-isothiocyanatocyclohexane, 1-isocyanato-4-isothiocyanatobenzene, 4-methyl-3-isocyanato-1-isothiocyanatobenzene, 2-isocyanato-4, 6-diisothiocyanato-1, 3, 5-triazine, 4-isocyanato-4 '-isothiocyanato-diphenyl sulfide and 2-isocyanato-2' -isothiocyanatodiethyl disulfide.

The polycyanate reactant of the first component of the two-component composition can optionally be prepared from an active hydrogen material (a) (iii) selected from the group consisting of polyols having at least two hydroxyl groups, hydroxyl and thiol groups, and mixtures thereof. As used herein, "active hydrogen source" means a source having active hydrogen groups capable of forming covalent bonds with isocyanate and isothiocyanate groups.

Alternative active hydrogen feedstocks (a) (iii) alternative polyol types include, but are not limited to: straight or branched chain alkane polyols such as 1, 2-ethanediol, 1, 3-propanediol, 1, 2-propanediol, 1, 4-butanediol, 1, 3-butanediol, glycerol, neopentyl glycol, trimethylolethane, trimethylolpropane, ditrimethylolpropane, erythritol, pentaerythritol and dipentaerythritol; polyalkylene glycols, such as diethylene glycol, dipropylene glycol and higher polyalkylene glycols such as polyethylene glycols having a number average molecular weight of, for example, 200 to 2000 g/mol; cycloalkane polyols such as cyclopentanediol, cyclohexanediol, cyclohexanetriol, cyclohexanedimethanol, hydroxypropylcyclohexanol, and cyclohexanediol; aromatic polyols such as dihydroxybenzene, benzenetriol, hydroxybenzyl alcohol, and dihydroxytoluene; bisphenols, such as 4, 4 '-isopropylidenediphenol, 4' -oxydiphenol, 4 '-dihydroxybenzophenone, 4' -thiobisphenol, phenolphthalein, bis (4-hydroxyphenyl) methane, 4 '- (1, 2-ethenediyl) bisphenol, and 4, 4' -sulfonylbisphenol; halogenated bisphenols, such as 4, 4 ' -isopropylidenebis (2, 6-dibromophenol), 4 ' -isopropylidenebis (2, 6-dichlorophenol) and 4, 4 ' -isopropylidenebis (2, 3, 5, 6-tetrachlorophenol); alkoxylated bisphenols, for example alkoxylated 4, 4' -isopropylidenediphenol having 1 to 70 alkoxy groups such as ethoxy, propoxy, α -butoxy and β -butoxy; and biscyclohexanols which can be prepared by hydrogenation of the corresponding bisphenols, for example 4, 4 ' -isopropylidene-biscyclohexanol, 4 ' -oxydicyclohexanol, 4 ' -thiobicyclohexanol and bis (4-hydroxycyclohexanol) methane.

In one embodiment of the present invention, the polyol of choice for the optional active hydrogen source (a) (iii) is a polyurethane prepolymer having two or more hydroxyl groups. The hydroxyl functional polyurethane prepolymers suitable for use in the present invention can be prepared from any of the polyols listed above and suitable polyisocyanates. The molar equivalent ratio of hydroxyl groups to isocyanate groups is selected so as to produce a hydroxyl functional polyurethane prepolymer that is substantially free of isocyanate groups. Examples of polyisocyanates suitable for use in preparing the hydroxyl functional polyurethane prepolymers include those previously described. The optional active hydrogen starting material (a) (iii) optionally hydroxyl functional polyurethane prepolymer typically has a number average molecular weight (Mn) of less than 50000, preferably less than 20000, more preferably less than 10000g/mol, as measured by Gel Permeation Chromatography (GPC) using polystyrene standards.

Examples of alternative hydroxyl and thiol containing materials for the alternative active hydrogen source materials (a) (iii) include, but are not limited to, 2-mercaptoethanol, 3-mercapto-1, 2-propanediol, glycerol bis (2-mercaptoacetate), glycerol bis (3-mercaptopropionate), 1-hydroxy-4-mercaptocyclohexane, 2, 4-dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 1, 3-dimercapto-2-propanol, 2, 3-dimercapto-1-propanol, 1, 2-dimercapto-1, 3-butanediol, trimethylolpropane bis (2-mercaptoacetate), trimethylolpropane bis (3-mercaptopropionate), pentaerythritol mono (2-mercaptoacetate), Pentaerythritol bis (2-mercaptoacetate), pentaerythritol tris (2-mercaptoacetate), pentaerythritol mono (3-mercaptopropionate), pentaerythritol bis (3-mercaptopropionate), pentaerythritol tris (3-mercaptopropionate), hydroxymethyl-tris (mercaptoethylthiomethyl) methane, 1-hydroxyethylthio-3-mercaptoethylthiobenzene, 4-hydroxy-4' -mercaptodiphenylsulfone, dihydroxyethyl sulfide mono (3-mercaptopropionate), and hydroxyethylthiomethyl-tris (mercaptoethylthio) methane.

The reaction of the polythiol monomer (a) (i), polycyanate monomer (a) (ii), and optional active hydrogen starting material (a) (iii) can be carried out in the presence of a suitable catalyst. Types of suitable catalysts include, but are not limited to, tertiary amines such as triethylamine and organometallic compounds such as dibutyltin dilaurate. Other examples of catalysts that can be used to prepare the polycyanate reactant are described below. If a catalyst is used in the preparation of the polycyanate reactant, it is generally present in an amount less than 5 weight percent, preferably less than 3 weight percent, and more preferably less than 1 weight percent, based on the total weight of (a) (i), (a) (ii), and (a) (iii).

The polyamine reactant of the second component (b) of the two-component composition may be selected from aliphatic polyamines, cycloaliphatic polyamines, aromatic polyamines and mixtures thereof. The polyamine reactant has at least two members selected from the group consisting of primary amines (-NH)₂) A secondary amine (-NH-), and combinations thereof. Preferably, the polyamine reactant has at least two primary amine groups.

The polyamine reactant may be selected from any of the ethylene amine families, such as Ethylene Diamine (EDA), diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA), piperazine, diethylene diamine (DEDA), and 2-amino-1-ethyl piperazine. The polyamine reactant may also be selected from C₁-C₃One or more isomers of dialkyltoluenediamines, such as 3, 5-dimethyl-2, 4-toluenediamine, 3, 5-dimethyl-2, 6-toluenediamine, 3, 5-diethyl-2, 4-toluenediamine, 3, 5-diethyl-2, 6-toluenediamine, 3, 5-diisopropyl-2, 4-toluenediamine, 3, 5-diisopropyl-2, 6-toluenediamine, and mixtures thereof. Other examples of polyamines from which the polyamine reactant may be selected include, but are not limited to, methylenedianiline and propyleneglycol bis (p-aminobenzoate).

In one embodiment of the present invention, the polyamine reactant can be generally described as having one of the following general structures (IV-VI):

particularly preferred structures include one or more diamines of the formulae VII-XX:

wherein R is₃And R₄Independently is C₁-C₃Alkyl radical, R₅Selected from hydrogen and halogens, such as chlorine and bromine. Diamines of formula VII may be generally referred to as 4, 4' -methylene-bis (dialkylanilines). Specific examples of diamines of formula VII include, but are not limited to, 4 '-methylene-bis (2, 6-dimethylaniline), 4' -methylene-bis (2, 6-diethylaniline), 4 '-methylene-bis (2-ethyl-6-methylaniline), 4' -methylene-bis (2, 6-diisopropylaniline), 4 '-methylene-bis (2-isopropyl-6-methylaniline), and 4, 4' -methylene-bis (2, 6-diethyl-3-chloroaniline). A preferred diamine of formula VII is 4, 4' -methylene-bis (2, 6-diethyl-3-chloroaniline).

According to the process of the invention, the polymerization of the two-component composition can be carried out by: mixing the first and second components together, for example with a high speed mixer or extruder; optionally degassing the mixture; optionally adding the mixture to a mold; the mold and the mixture therein are then heated for a period of time. The thermal cure cycle used may vary depending on, for example, the reactivity and molar ratio of the components and the presence of any catalyst. Typically, the thermal curing cycle involves heating the mixture of the two-part composition from room temperature up to 200 ℃ in 0.5 to 72 hours.

Catalysts that may be used with the two-component composition include, for example, tertiary amines (such as triethylamine, triisopropylamine, and N, N-dimethylbenzylamine) and organometallic compounds (such as dibutyltin dilaurate, dibutyltin diacetate, and stannous octoate). Further examples of tertiary amines are listed in US5693738 at column 10, lines 6 to 38, incorporated herein by reference. Other examples of organometallic compounds suitable for use as catalysts are listed in US 561339, column 4, lines 26-46, incorporated herein by reference. If used, the catalyst is typically incorporated into the first and second components of the two-component composition prior to mixing of the second component. The catalyst content is typically less than 5% by weight, preferably less than 3% by weight, more preferably less than 1% by weight, based on the total weight of the combined first and second components.

The first and second components of the two-component composition are typically present in amounts sufficient to result in (NCO + NCS)/(-NH)₂+ -NH-) in a molar equivalent ratio of 0.5 to 3.0, preferably 0.5 to 1.5, more preferably 0.8 to 1.2.

Various conventional additives may be incorporated into the two-part organic composition polymerized according to the process of the present invention. The additives may include light stabilizers, heat stabilizers, antioxidants, ultraviolet light absorbers, mold release agents, static (non-photochromic) dyes, pigments, and toughening agents such as alkoxylated phenol benzoates and poly (alkylene glycol) dibenzoates. Yellowing prevention additives such as 3-methyl-2-butenol, organic pyrocarbonates, and triphenyl phosphite (CAS registry No.101-02-0) may also be added to the two-part organic composition to improve yellowing resistance. These additives are typically present in the two-part composition in a total amount of less than 10 weight percent, preferably less than 5 weight percent, and more preferably less than 3 weight percent, based on the total weight of the combined first and second parts. While these conventional additives may be added to either the first or second component of the composition, they are typically incorporated into the second component to reduce potential side effects with the isocyanate or isothiocyanate groups of the first component.

The polymers prepared according to the process of the invention will be solid, preferably transparent, and suitable, for example, for optical or ophthalmic applications. The polymers of the present invention also have a refractive index of at least 1.6, preferably at least 1.63, more preferably at least 1.65; a sufficiently high abbe number, for example an abbe number of at least 33, preferably at least 35; a zero second Babbitt hardness of at least 1; and good impact resistance. The reactants and compounds making up the first and second components of the two-component composition and the amounts combined may be selected so that the polymers prepared therefrom have the characteristics listed above. Solid articles that can be prepared according to the methods of the present invention include, but are not limited to, optical lenses such as plano-lenses, spectacles, sunglasses, windows, automotive transparencies such as windshields, side and back lighting, and aerospace transparencies, among others.

For use in the preparation of photochromic articles, such as lenses, the polymer should be transparent to the portion of the electromagnetic spectrum that activates the photochromic substance incorporated in the matrix, i.e., the Ultraviolet (UV) light wavelengths that produce a colored or open photochromic substance and the portion of the visible spectrum that includes the UV activated form, i.e., the wavelength of maximum absorption of the open photochromic substance. Photochromic substances that can be used with the polymers of the present invention are organic photochromic compounds or substances containing said compounds that can be incorporated, for example, dissolved, dispersed or diffused into said polymers.

A first group of organic photochromic substances useful in forming the photochromic articles of the present invention are those having an activated absorption peak in the visible range greater than 590nm, for example between greater than 590 and 700 nm. These materials typically appear blue, blue-green, or blue-violet when exposed to ultraviolet light in a suitable solvent or matrix. Examples of the types of such materials suitable for use in the present invention include, but are not limited to, spiro (indoline) phenoxazines and spiro (indoline) benzoxazines. These and other classes of photochromic substances are described in the open literature. See, e.g., US 3562172; 3578602, respectively; 4215010, respectively; 4342668, respectively; 5405958, respectively; 4637698, respectively; 4931219, respectively; 4816584, respectively; 4880667, respectively; 4818096. see also, for example: JP 62/195383; and Techniques in Chemistry, Volume III, "Photochromym", Chapter 3, Glenn H.Brown, Editor, John Wiley and Sons, Inc., New York, 1971.

A second group of organic photochromic substances useful in forming the photochromic articles of the present invention are those having at least one absorption peak, preferably two absorption peaks, in the visible range between 400 and less than 500 nm. These materials are typically yellow-orange in color when exposed to ultraviolet light in a suitable solvent or matrix. Such compounds include certain chromenes, i.e., benzopyrans and naphthopyrans. Many such chromenes are described in published documents such as US 3567605; 4826977, respectively; 5066818, respectively; 4826977, respectively; 5066818, respectively; 5466398, respectively; 5384077, respectively; 5238931, respectively; and 5274132.

A third group of organic photochromic substances useful in forming the photochromic articles of the present invention are those having one absorption peak in the visible range between 400 and 500nm and another absorption peak in the visible range between 500 and 700 nm. These materials typically exhibit a color in the yellow/brown to violet/gray range when exposed to ultraviolet light in a suitable solvent or matrix. Examples of such materials include certain benzopyran compounds, having a substituent at the 2-position of the pyran ring and a substituted or unsubstituted heterocyclic ring, such as a benzothiophene or benzofuran ring fused to the benzene portion of the benzopyran. This substance is the subject of US 5429774.

Other photochromic substances are photochromic organometallic dithizonates, i.e. (arylazo) -thiocarbonylhydrazines, such as mercury dithizonates, as described, for example, in US 3361706. Fulgides and fulgimides such as 3-furyl and 3-thienyl fulgides and fulgimides are described in US 4931220, column 20, line 5 to column 21, line 38.

The disclosures of such photochromic materials in the above-mentioned patents are incorporated herein by reference in their entirety. The photochromic articles of the present invention can comprise one photochromic material or a mixture of photochromic materials, as desired. Mixtures of photochromic substances can be used to obtain certain activated colors such as a nearly neutral gray or brown.

The photochromic substances described herein are used in amounts and proportions (when mixtures are used) such that the polymer incorporating or using the mixture of compounds exhibits the desired color, for example, substantially achromatic as would be imparted by the color of the activated photochromic substance as a gray or brown shade when activated by unfiltered sunlight, i.e., as close as possible to the color of the activated photochromic substance. The relative amounts of the above photochromic substances will vary in part with the relative intensities of the activated substance colors of the compounds and the desired final color.

The photochromic compounds or materials described herein can be coated onto or incorporated into the polymer by a variety of methods described in the art. This method comprises dissolving or dispersing the substance in the polymer, for example by immersing the polymer in a hot solution of the photochromic substance or by imbibing the photochromic substance into the polymer by heat transfer; providing the photochromic substance as a separate layer between adjacent polymer layers, for example as part of a polymer film; and applying the photochromic substance to the polymeric surface as a coating or as part of a coating or polymeric surface coating. The term "imbibe" means and includes penetration of the photochromic substance alone into the polymer, transfer uptake of the photochromic substance into the porous polymer with the aid of a solvent, vapor phase transfer, and other transfer mechanisms. One example of the inhalation method comprises the steps of: coating the photochromic article with a photochromic substance; heating the surface of the photochromic article; the remaining coating is then removed from the surface of the photochromic article.

The amount of photochromic substance or composition comprising the same applied to or incorporated into the polymer is not limited so long as it is sufficient to produce a photochromic effect discernible to the naked eye upon activation. This amount can generally be referred to as a photochromic amount. The specific amount is generally related to the desired color intensity upon irradiation and the method used to blend or coat the photochromic substance. Typically, the greater the amount of photochromic substance used, the greater the intensity of the color. The total amount of photochromic substance incorporated or applied to the photochromic optical polymer can generally be from 0.15 to 0.35mg/cm²Within the range of the surface into which the photochromic substance is incorporated or coated.

Photochromic substances can be added to the two-part organic composition prior to polymerization, e.g., cast curing, of the composition. In doing so, however, it is preferred that the photochromic substance be resistant to potential side effects with the initiator(s) that may be present and/or the isocyanate, isothiocyanate and amine groups of the first and second components. These side effects can result in the deactivation of the photochromic substances, for example by trapping them in the open or closed position. Photochromic substances may also include photochromic pigments and organic photochromic substances encapsulated in metal oxides, the latter being described in US 4166043 and 4367170. Organic photochromic substances that are well encapsulated within an organic polymer matrix as described in US 4931220 may also be incorporated into the two-component composition of the present invention prior to curing. If the photochromic substance is incorporated into the two-part organic composition of the present invention prior to curing, it is typically incorporated into the second part before the first and second parts are mixed together.

Example 1

Thioglycerol bis (2-mercaptoacetate) is a preferred polythiol monomer of the invention, wherein R of formula I₁And R₂Are all methylene groups. Thioglycerol bis (2-mercaptoacetate) was prepared from the following ingredients.

(a) 5% by weight aqueous ammonia solution.

The ingredients of feed 1 were charged to a 5 liter round bottom flask equipped with a magnetic stirrer, a thermocouple and heating mantle coupled by a temperature feedback control device, and a vacuum distillation column. A vacuum of 5-10mmHg was pulled, and the reaction mixture was heated and maintained at 70 ℃ for 4 to 5 hours while collecting water from the distillation column.

Upon observing that no more water was collected from the distillation column, the reaction mixture was allowed to cool to room temperature and transferred to a 6 liter round bottom flask equipped with a motor driven stirring paddle, thermocouple, and water cooling jacket. Charge 2 was added to the mixture, which was then stirred for 30 to 45 minutes, with an exotherm of 10 to 20 ℃. Upon cooling to room temperature, the reaction mixture was allowed to stand to accumulate the upper layer of ammonia and was removed by pipette. The remaining lower layer was washed three times with 2 liters of deionized water each time. Vacuum desorption of water from the washed layer yielded 1995g of thioglycerol bis (2-mercaptoacetate) as a pale yellow oil with a refractive index of 1.5825.

Examples 2 and 3

Mixing polyisocyanate with polythiol (example 2) and also with polyol (example 3) at 80 ℃ for 2 hours produced a viscous first component prepolymer. The warm first component prepolymer is rapidly stirred and the second component diamine is added. After stirring the mixture for a few seconds, the mixture was immediately filled between two flat glass molds. The filled mold was heated to 120 ℃ and held at this temperature for 16 hours, yielding a plastic panel. The polyisocyanates used in these examples are α, α' -Xylylene Diisocyanate (XDI) and bis (isocyanatocyclohexyl) methane (H-MDI). The dithiol and Polyol are 2, 2' -thiodiethylene thiol (DMDS) and Tone Polyol 32B8(UC32B8), available from Union carbide Corporation, Danbury, Connecticut. The second component polyamine is diethyltoluenediamine (DETDA). The molar composition and molar ratio of each component used in each example are shown in table 1. The physical properties measured in each example are shown in Table 2.

Example 4

The first component was prepared by mixing 0.6 equivalent of H-MDI with 1 equivalent of DMDS at 90 ℃ for 1 hour. To the first component was added 0.6 equivalents of XDI with stirring. The mixture was stirred for an additional 1.5 hours to yield a viscous prepolymer. To the warm prepolymer was added 0.25 equivalents of DETDA. After stirring for a few seconds, the mixture is filled between two flat glass molds. The filled mold was heated to 120 ℃ and held at this temperature for 16 hours, yielding a plastic panel.

¹With B&L Abbe Refractometer (AR) measurements

²Using polarizing microscopyMirror (PLM) measurements.

These examples demonstrate that the polymers according to the invention have an extremely high refractive index, a high Abbe number and a good hardness (impact resistance).

The invention has been described with reference to the preferred embodiments. Obvious modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. A method of preparing a polymer comprising the step of polymerizing a two-part composition consisting of:

(i) a polythiol monomer having at least two thiol groups; and

2. The method of claim 1, wherein the first component further comprises

(iii) An active hydrogen source having at least two active hydrogen groups selected from the group consisting of polyols, hydroxyl and thiol bearing materials, and mixtures thereof.

3. The process of claim 1, wherein the relative amounts of (i) and (ii) in the first component are selected such that the molar equivalent ratio of (NCO + NCS)/(SH) is greater than 1.0.

4. The process of claim 2 wherein the relative amounts of (i), (ii) and (iii) in said first component are selected such that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is greater than 1.0.

5. The process of claim 1 wherein said first component and said second component are selected such that when they are polymerized the resulting polymer has a refractive index of at least 1.6, an Abbe number of at least 33 and an initial Babbitt hardness of at least 1.

6. The process of claim 2, wherein the relative amounts of (i), (ii) and (iii) are selected so that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is from 1.2: 1.0 to 4.0: 1.0.

7. The process of claim 1 wherein said polythiol monomer is selected from the group consisting of 2, 5-dimercaptomethyl-1, 4-dithiane, 2 '-thiodiethanethiol, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (2-mercaptoacetate), 4-mercaptomethyl-3, 6-dithio-1, 8-octanedithiol, 4-tert-butyl-1, 2-benzenedithiol, 4' -thiodithiol, benzenedithiol, ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (2-mercaptopropionate), and mixtures thereof, A polythiol of the formula:

wherein R is₁And R₂Independently selected from the group consisting of straight or branched chain alkylene, cycloalkylene, phenylene and C₁-C₉Alkyl-substituted phenylene, oligomers of the polythiol; and a mixture of said polythiol monomers.

8. The process of claim 7, wherein the polythiol oligomer has disulfide linkages and is prepared by reacting a polythiol monomer with sulfur in the presence of a basic catalyst.

9. The process of claim 7 wherein said polythiol oligomer is represented by the general formula:

wherein n is an integer from 1 to 21.

10. The process of claim 7 wherein said polythiol oligomer is represented by the general formula:

wherein R is₁And R₂Independently selected from the group consisting of straight or branched chain alkylene, cycloalkylene, phenylene and C₁-C₉An alkyl-substituted phenylene group, n and m are independently integers from 0 to 21 such that n + m is at least 1.

11. The method of claim 1, wherein said polycyanate monomer is a polycyanate having at least two isocyanate groups.

12. The method of claim 1, wherein said polycyanate monomer is a polycyanate having one or more sulfur atoms in the backbone.

13. The method of claim 12, wherein the polycyanate monomer having one or more sulfur atoms in the backbone has the general structure:

wherein R is₁₀And R₁₁Independently is C₁-C₃An alkyl group.

14. The process of claim 11 wherein said polycyanate monomer is selected from the group consisting of α, α '-xylylene diisocyanate, α, α, α', α '-tetramethylxylylene diisocyanate, isophorone diisocyanate, bis (isocyanatocyclohexyl) methane, o-toluidine diisocyanate, o-benzylidene diisocyanate, and 4, 4' -diphenylmethane diisocyanate, and mixtures of said polycyanate monomers.

15. The process of claim 1, wherein said polyamine reactant of said second component is selected from the group consisting of ethyleneamine family polyamines, C₁-C₃Dialkyltoluenediamine, methylenedianiline, trimethylenediol bis (p-aminobenzoate), a diamine represented by the general formula (a):

(A)

a diamine represented by the general formula (B):

(B)

and a diamine represented by the general formula (C):

(C)

16. the process of claim 15 wherein the diamine of formula (a) is selected from one or more of the following diamines:

(IX)

(X)

wherein R is₃And R₄Independently is C₁-C₃Alkyl radical, R₅Selected from hydrogen and halogen.

17. The process of claim 15 wherein the diamine of formula (B) is selected from one or more of the following diamines:

(XIII)

18. The process of claim 15 wherein the diamine of formula (C) is selected from one or more of the following diamines:

19. The method of claim 1, further comprising the step of adding a catalyst to said two-part composition.

20. The process of claim 16 wherein the catalyst is selected from the group consisting of tertiary amines and organometallic compounds.

21. The method of claim 1, further comprising the steps of:

mixing the first component and the second component.

22. The method of claim 1, further comprising the steps of:

degassing the first component.

23. The method of claim 1, further comprising the steps of:

degassing the second component.

24. The method of claim 21, further comprising the steps of:

the mixture is added to a mold.

25. The method of claim 24, further comprising the steps of:

heating the mold and the mixture of the first component and the second component therein.

26. The method of claim 25, wherein the heating step further comprises heating the mold and the mixture to a temperature of up to 200 ℃ over a period of 0.5 to 72 hours.

27. The method of claim 1, wherein said first component and said second component are present in amounts sufficient to result in (NCO + NCS)/(-NH)₂+-NH-) in a molar equivalent ratio of 0.5 to 3.0.

28. The method of claim 1, further comprising the step of adding an additive selected from the group consisting of light stabilizers, heat stabilizers, antioxidants, ultraviolet light absorbers, mold release agents, static dyes, pigments, toughening agents, and anti-yellowing additives; and mixtures of said additives.

29. The method of claim 28 wherein said additive is present in said two-part composition in an amount of up to 10% by weight of said two-part composition.

30. The method of claim 1, wherein the polymer further comprises a photochromic substance.

31. A polymer prepared by polymerization of a two-part composition according to the method of claim 1, the two-part composition consisting of:

(i) a polythiol monomer having at least two thiol groups; and

(ii) a polycyanate monomer having at least two functional groups selected from isocyanate, isothiocyanate and combinations thereof; the number average molecular weight of the first component is 500-; and

(b) a second component comprising at least one polyamine reactant having at least two functional groups selected from the group consisting of primary amines, secondary amines, and combinations thereof;

the first and second components are present in amounts sufficient to result in (NCO + NCS)/(-NH)₂+ -NH-) in a molar equivalent ratio of 0.5 to 3.0.

32. The polymer of claim 31 wherein said first component further comprises (iii) an active hydrogen material having at least two active hydrogen groups, said active hydrogen material being selected from the group consisting of polyols, hydroxyl and thiol containing materials, and mixtures thereof.

33. The polymer of claim 31, wherein the relative amounts of (i) and (ii) in said first component are selected such that the molar equivalent ratio of (NCO + NCS)/(SH) is greater than 1.0.

34. The polymer of claim 32, wherein the relative amounts of (i), (ii), and (iii) in said first component are selected such that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is greater than 1.0.

35. The polymer of claim 31, wherein said first component and said second component are selected such that when they are polymerized, the resulting polymer has a refractive index of at least 1.6, an abbe number of at least 33, and an initial babbitt hardness of at least 1.

36. The polymer of claim 34, wherein the relative amounts of (i), (ii) and (iii) are selected so that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is from 1.2: 1.0 to 4.0: 1.0.

37. The polymer of claim 31, wherein said polythiol monomer is selected from the group consisting of 2, 5-dimercaptomethyl-1, 4-dithiane, 2 '-thiodiethanethiol, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (2-mercaptoacetate), 4-mercaptomethyl-3, 6-dithio-1, 8-octanedithiol, 4-tert-butyl-1, 2-benzenedithiol, 4' -thiodithiol, benzenedithiol, ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (2-mercaptopropionate), and mixtures thereof, And polythiols of the general formula:

38. The polymer of claim 37, wherein said polythiol oligomer has disulfide linkages and is prepared by reacting a polythiol monomer with sulfur in the presence of a basic catalyst.

39. The polymer of claim 37, wherein said polythiol oligomer is represented by the general formula:

wherein n is an integer from 1 to 21.

40. The polymer of claim 37, wherein said polythiol oligomer is represented by the general formula:

41. The polymer of claim 31, wherein said polycyanate monomer is a polycyanate having at least two isocyanate groups.

42. The polymer of claim 41, wherein said polycyanate monomer is selected from the group consisting of α, α '-xylylene diisocyanate, α, α, α', α '-tetramethylxylylene diisocyanate, isophorone diisocyanate, bis (isocyanatocyclohexyl) methane, o-toluidine diisocyanate, o-benzylidene diisocyanate, and 4, 4' -diphenylmethane diisocyanate, and mixtures of said polycyanate monomers.

43. The polymer of claim 31 wherein said polyamine reactant of said second component is selected from the group consisting of ethyleneamine group polyamines, C₁-C₃Dialkyltoluenediamine, methylenedianiline, trimethylenediol bis (p-aminobenzoate), a diamine represented by the general formula (a):

(A)

a diamine represented by the general formula (B):

(B)

and a diamine represented by the general formula (C):

(C)

44. a polymer according to claim 43, wherein the diamine of formula (A) is selected from one or more of the following diamines:

(IX)

(X)

45. A polymer according to claim 43, wherein the diamine of formula (B) is selected from one or more of the following diamines:

46. A polymer according to claim 43, wherein the diamine of formula (C) is selected from one or more of the following diamines:

47. The polymer of claim 31 wherein a catalyst is added to the two-part composition to promote polymerization.

48. The polymer of claim 47, wherein the catalyst is selected from the group consisting of tertiary amines and organometallic compounds.

49. The polymer of claim 31, wherein the polymerization process further comprises the steps of:

mixing the first component and the second component.

50. The polymer of claim 31, wherein the polymerization further comprises the steps of:

degassing the first component.

51. The polymer of claim 31, wherein the polymerization further comprises the steps of:

degassing the second component.

52. The polymer of claim 49, wherein said polymerization further comprises the steps of:

the mixture is added to a mold.

53. The polymer of claim 52, wherein said polymerization further comprises the steps of:

54. The polymer of claim 53, wherein the heating step further comprises heating the mold and the mixture to a temperature of up to 200 ℃ over a period of 0.5 to 72 hours.

55. The polymer of claim 31 further comprising an additive selected from the group consisting of light stabilizers, heat stabilizers, antioxidants, ultraviolet light absorbers, mold release agents, static dyes, pigments, toughening agents, and anti-yellowing additives; and mixtures of said additives.

56. The polymer of claim 55, wherein said additive is present in said polymer in an amount up to 10% by weight of said polymer.

57. The polymer of claim 31, further comprising a photochromic substance.

58. The polymer of claim 31, wherein said polycyanate monomer having one or more sulfur atoms in the backbone has the general structure:

wherein R is₁₀And R₁₁Independently is C₁-C₃An alkyl group.

59. A photochromic article derived from a polymer and a photochromic substance prepared by polymerization of a two-part composition according to the process of claim 1, said two-part composition consisting of:

(i) a polythiol monomer having at least two thiol groups; and

60. The photochromic article of claim 59 wherein said first component further comprises (iii) an active hydrogen material having at least two active hydrogen groups selected from the group consisting of polyols, hydroxyl and thiol bearing materials, and mixtures thereof.

61. The photochromic article of claim 59 wherein the relative amounts of (i) and (ii) in said first component are selected so that the molar equivalent ratio of (NCO + NCS)/(SH) is greater than 1.0.

62. The photochromic article of claim 60 wherein the relative amounts of (i), (ii) and (iii) in said first component are selected so that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is greater than 1.0.

63. The photochromic article of claim 59 wherein said first component and said second component are selected such that when they are polymerized the resulting polymer has a refractive index of at least 1.6, an Abbe number of at least 33 and an initial Babbitt hardness of at least 1.

64. The photochromic article of claim 60 wherein the relative amounts of (i), (ii) and (iii) are selected so that the molar equivalent ratio of (NCO + NCS)/(SH + OH) is from 1.2: 1.0 to 4.0: 1.0.

65. The photochromic article of claim 59 wherein said polythiol monomer is selected from the group consisting of 2, 5-dimercaptomethyl-1, 4-dithiane, 2 '-thiodiethanethiol, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (2-mercaptoacetate), 4-mercaptomethyl-3, 6-dithio-1, 8-octanedithiol, 4-tert-butyl-1, 2-benzenedithiol, 4' -thiodithiol, benzenedithiol, ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (2-mercaptoacetate), and mixtures thereof, Polyethylene glycol bis (3-mercaptopropionate), a polythiol of the general formula:

66. The photochromic article of claim 65 wherein said polythiol oligomer has disulfide linkages and is prepared by reacting a polythiol monomer with sulfur in the presence of a basic catalyst.

67. The photochromic article of claim 65 wherein said polythiol oligomer is represented by the general formula:

wherein n is an integer from 1 to 21.

68. The photochromic article of claim 65 wherein said polythiol oligomer is represented by the general formula:

69. The photochromic article of claim 59 wherein said polycyanate monomer is a polycyanate having at least two isocyanate groups.

70. The photochromic article of claim 69 wherein said polycyanate monomer is selected from the group consisting of α, α '-xylylene diisocyanate, α, α', α '-tetramethylxylylene diisocyanate, isophorone diisocyanate, bis (isocyanatocyclohexyl) methane, o-toluidine diisocyanate, o-benzylidene diisocyanate, and 4, 4' -diphenylmethane diisocyanate, and mixtures of said polycyanate monomers.

71. The photochromic article of claim 59 wherein said polyamine reactant of said second component is selected from the group consisting of ethyleneamine family polyamines, C₁-C₃Dialkyltoluenediamine, methylenedianiline, trimethylenediol bis (p-aminobenzoate), a diamine represented by the general formula (a):

(A)

a diamine represented by the general formula (B):

(B)

and a diamine represented by the general formula (C):

(C)

72. the photochromic article of claim 71 wherein the diamine of formula (A) is selected from one or more of the following diamines:

73. The photochromic article of claim 71 wherein the diamine of formula (B) is selected from one or more of the following diamines:

74. The photochromic article of claim 71 wherein the diamine of formula (C) is selected from one or more of the following diamines:

75. The photochromic article of claim 59 wherein a catalyst is added to said two-part composition to promote polymerization.

76. The photochromic article of claim 75 wherein said catalyst is selected from the group consisting of tertiary amines and organometallic compounds.

77. The photochromic article of claim 59 wherein said polymerization process further comprises the steps of:

mixing the first component and the second component.

78. The photochromic article of claim 59 wherein said polymerization process further comprises the steps of:

degassing the first component.

79. The photochromic article of claim 59 wherein said polymerization process further comprises the steps of:

degassing the second component.

80. The photochromic article of claim 59 wherein said polymerization process further comprises the steps of:

the first and second component mixtures are added to a mold.

81. The photochromic article of claim 80 wherein said polymerization process further comprises the steps of:

heating the mold and the mixture therein.

82. The photochromic article of claim 81 wherein said heating step further comprises heating said mold and said mixture to a temperature of up to 200 ℃ for a period of time of from 0.5 to 72 hours.

83. The photochromic article of claim 59 further comprising an additive selected from the group consisting of light stabilizers, heat stabilizers, antioxidants, ultraviolet light absorbers, mold release agents, static dyes, pigments, toughening agents, and anti-yellowing additives; and mixtures of said additives.

84. The photochromic article of claim 83 wherein said additive is present in said polymer in an amount of up to 10 percent by weight of said polymer.

85. The photochromic article of claim 59 wherein said photochromic substance is mixed with said first component.

86. The photochromic article of claim 59 wherein said photochromic substance is mixed with said second component.

87. The photochromic article of claim 59 wherein the photochromic substance is present at 0.15 to 0.35mg/cm²The amount of surface area of the photochromic article is applied to the photochromic article.

88. The photochromic article of claim 59, wherein the photochromic substance is selected from the group consisting of spiro (indoline) phenoxazines, spiro (indoline) benzoxazines, chromenes, benzopyrans, naphthopyrans, organometallic dithizonates, (arylazo) -thiocarbonylhydrazines, mercuriumdithizonates, fulgides, fulgimides, 3-furanyl fulgides, 3-thienyl fulgides, 3-furanyl fulgimides and 3-thienyl fulgimides; and mixtures of said photochromic substances.

89. A photochromic article according to claim 59 wherein said photochromic substance has an activated absorption peak in the visible range between 590 and 700 nm.

90. The photochromic article of claim 59 wherein said photochromic substance has an activated absorption peak in the visible range between 400 and 500 nm.

91. The photochromic article of claim 59 wherein said photochromic substance has an activated absorption peak in the visible range between 500 and 700 nm.

92. The photochromic article of claim 59 wherein said photochromic substance is coated on or incorporated into said photochromic article by a method selected from the group consisting of cast curing, encapsulation within a matrix of an organic polymer, and incorporation into said two-part composition prior to curing.

93. The photochromic article of claim 59 wherein a photochromic substance is applied by imbibing said photochromic article such that said photochromic substance penetrates into said polymer.

94. The photochromic article of claim 93 wherein said imbibition process comprises imbibition via solvent transfer.

95. The photochromic article of claim 93 wherein said imbibition process comprises vapor phase transfer.

96. The photochromic article of claim 93 wherein said photochromic substance is applied as a coating to the surface of said photochromic article.

97. The photochromic article of claim 93 wherein said imbibing process comprises the steps of:

coating the photochromic article with a photochromic substance;

heating the surface of the photochromic article; and

the remaining coating is removed from the surface of the photochromic article.

98. The photochromic article of claim 59 wherein said photochromic article is an optical lens for correcting a visual deficit.

99. The photochromic article of claim 59 wherein said polycyanate monomer has one or more sulfur atoms in the backbone.

100. The photochromic article of claim 99 wherein the polycyanate monomer containing one or more sulfur atoms in the backbone has the general structure:

wherein R is₁₀And R₁₁Independently is C₁-C₃An alkyl group.