GB2168985A

GB2168985A - Polyol (allyl carbonate) compositions and polymerizates

Info

Publication number: GB2168985A
Application number: GB08531225A
Authority: GB
Inventors: Michael Stephen Misura
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Inc
Priority date: 1984-12-28
Filing date: 1985-12-19
Publication date: 1986-07-02
Also published as: JPS61162506A; DE3545628A1; FR2575478A1; DE3545628C2; GB2168985B; IT1188094B; GB8531225D0; FR2575478B1; IT8568109A0

Abstract

A solution suitable for use in the manufacture of tinted optical products comprises (a) liquid allylic-functional material comprising polyol (allyl carbonate) monomer, liquid polyol (ally carbonate) polymer, or a mixture thereof, and (b) bromoxylenol blue. A pourable, polymerizable composition may be produced by incorporating a thermally decomposable polymerization initiator.

Description

SPECIFICATION Polyol (allyl carbonate) compositions and polymerizates The present invention relates to compositions based on allylic-functional materials. More particularly it relates to solutions and pourable compositions containing polyol (allyl carbonate) monomers and/or polymers and the production of polymerizates therefrom.

Pourable, polymerizable compositions containing polyol (allyl carbonate) material and various initiators have been used to produce various polymeric articles, especially those such as ophthalmic lenses, face shields, and the like, which are generally transparent to at least portions of the visible spectrum. The polymerizates are typically formed by heating the polymerizable compositions to temperatures at which the initiator decomposes at a rate sufficient to initiate polymerization which then proceeds to the desired degree, which is usually substantially complete polymerization.

In many cases it is desirable to incorporate into the polymerizable compositions one or more dyes in order to produce polymerizates of various colours. Coloured polymerizates have a variety of uses including tinted ophthalmic lenses, lenses for sunglasses, optical filters, shields for welders, and face masks.

Many dyes have been tried in the polymerizable compositions, but in only a very few instances have the dyes remained stable during the polymerization process. Although it is not desired to be bound by any theory, it is believed that the initiator reacts chemically with the dye during the polymerization process. Whatever the reason, the result is typically a polymerizate in which the colour is severely faded or severely changed in hue or both, as compared to the colour of the polymerizable composition containing the dye.

Many dyes have also been tried in an effort to produce, from pourable, polymerizable compositions containing polyol (allyl carbonate) material, polymerizates which are brilliant yellow in colour. Several dyes tend to induce a yellow-orange or brownish yellow colour to such polymerizates, but few dyes, if any at all, have been found which are sufficiently soluble in the polymerizable composition and which provide a brilliant yellow colour to the polymerizate.

It has now been found that bromoxylenol blue may be employed as dye for liquid allylic functional material, and that when a solution of the liquid allylic-functional material and the dye is polymerized using a thermally decomposable polymerization initiator, the colour imparted by the bromoxylenol blue remains substantially stable during the polymerization.

It has also been found that bromoxylenol blue imparts a brilliant yellow colour to polymerizates of allylic-functional material.

According to one embodiment of the present invention there is provided a solution which comprises (a) liquid allylic-functional material comprising polyol (allyl carbonate) monomer, liquid polyol (allyl carbonate) polymer, or a mixture thereof, and (b) bromoxylenol blue.

According to another embodiment ofthe present invention there is provided a pourable, polymerizable composition which comprises (a) liquid allylic-functional material comprising polyol (allyl carbonate) monomer, liquid polyol (allyl carbonate) polymer, or a mixture thereof, (b) bromoxylenol blue and (c) thermally decomposable polymerization initiator.

The present invention also provides a method which comprises heating the pourable, polymerizable composition of the present invention to form a polymerizate, and further provides a polymerizate provided by such a method.

Polyol (allyl carbonate) monomer which can be utilised in the practice of the present invention include the liquid allyl carbonates of linear or branched aliphatic or aromatic polyols, e.g. aliphatic glycol bis(allyl carbonate) compound or alkylidene bisphenol bis(allyl carbonate) compounds. These monomers can be described as unsaturated polycarbonates of polyols, e.g. glycols. The monomers can be prepared by procedures well known in the art, e.g. United States Patent Specifications 2 370 567 and 2403 113. In the procedure described in United States Patent Specification 2 113, the monomers are prepared by treating the polyol, e.g. glycol, with phosgene at temperatures between 0 C and 20"C to form the corresponding polychloroformate, e.g. dichloroformate.The polychloroformate is then reacted with an unsaturated alcohol in the presence of a suitable acid acceptor, e.g., pyridine, a tertiary amine, of an alkaline or alkaline earth metal hydroxide. Alternatively, the unsaturated alcohol can be reacted with phosgene and the resulting chloroformate reacted with the polyol in the presence of an alkaline reagent, as described in United States Patent Specification 2,370,567.

The polyol (allyl carbonate) monomers can be represented by the general formula:

wherein R1 is the radical derived from the unsaturated alcohol and is an allyl or substituted allyl group, R2 is the radical derived from the polyol and the average value of n is in the range of from 2 to about 5, preferably about 2.

For any particular compound the value of n is an integer. For mixtures of compounds, however, the average value of n may be a whole or a fractional number. The average value of n is based on the number average molecular weight of the polyol (allyl carbonate) monomer species constituting the mixture.

The allyl group (R,) may be substituted at the 2-position with a halogen, most notably chlorine or bromine, or an alkyl group containing from 1 to 4 carbon atoms, generally a methyl or ethyl group. The R1 radical may be represented by the general formula:

wherein R0 is hydrogen, halogen, or a C1 to C4 alkyl group. Specific examples of R1 include the groups: allyl, 2-chloroallyl, 2-bromoallyl, 2-fluoroallyl, 2-methallyl, 2-ethylallyl, 2-isopropylallyl, 2-n-propylallyl, and 2-n-butylallyl. Most commonly, R1 is the allyl group, H2=CH-CH2-.

R2 is a polyvalent radical derived from the polyol, which may be be an aliphatic or aromatic polyol that usually contains 2, 3,4 or 5 hydroxy groups. Typically, the polyol contains 2 hydroxy groups, i.e., a glycol or bisphenol. The aliphatic polyol may be linear or branched and contain from 2 to 10 carbon atoms. Commonly, the aliphatic polyol is an alkylene glycol having from 2 to 4 carbon atoms or a poly (C2-C4) alkylene glycol, e.g., ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, or triethylene glycol.

One class of aromatic polyols can be represented by the general formula:

wherein A is oxy, sulphonyl, or an alkylidene radical, having from 1 to 4 carbon atoms, e.g., methylene, ethylidene, dimethylmethylene (isopropylidene), each Ra independently represents a lower alkyl substituent of from 1 to 3 carbon atoms, and p and q are each independently 0, 1, 2, or 3. Preferably, the hydroxyl group is in the ortho or para position. The para position is especially preferred.

The polyols from which R2 is derived may also be polyol-functional chain extended compounds.

Examples of such compounds based on alkylene oxide extension include ethylene oxide extended trimethylolpropane, propylene oxide extended trimethylolpropane, ethylene oxide extended glycerol, and propylene oxide extended glycerol. Additional examples include ethylene oxide extended bisphenols such as those represented by the general formula:

where A, Ra, p, and q are as discussed above in respect of Formula Ill, and j and k are each independently 1, 2, 3, or 4. Many compounds based on lactone extension are described in United States Patent Specification 3,169,945.

Specific examples of the radical R2 include: alkylene groups containing from 2 to 10 crabon atoms such as ehtylene (-CH2-CH2-), trimethylene, methylethylene, tetramethylene, ethylethylene, pentamethylene, hexamethylene, 2-methylhexamethylene, octamethylene, and decamethylene; alkylene ether groups for example -CH2-O-CH2-, -CH2CH2-O-CH2CH2-, -CH2-O-CH2-CH2-, and -CH2CH2CH2-O-CH2CH2CH2-; alkylene polyether groups for example -CH2CH2-O CH2CH2-O-CH2CH2- and - CH2CH2CH2-O-CH2CH2CH2-O-CH2CH2CH2-; al kylene carbonate and alkylene ether carbonate groups for example -CH2CH2-O-CO-O-CH2CH2- and -CH2CH2-O CH2CH2-O-CO-O-CH2CH2-O-CH2CH2-; and isopropylidene bis(para-phenyl),

Most commonly, R2 is -CH2CH2-, -CH2CH2-O-CH2CH2-, or -CH2CH2-O-CH2CH2-O-CH2CH2-.

Specific examples of polyol (allyl carbonate) monomers useful in the practice of the present invention include ethylene glycol bis(2-chloroallyl carbonate), ethylene glycol bis(allyl carbonate), 1,4-butanediol bis(allyl carbonate), 1,5-pentanediol bis(allyl carbonate), 1,6-hexanediol bis(allyl carbonate), diethylene glycol bis(2-methallyl carbonate), diethylene glycol bis(allyl carbonate), triethylene glycol bis(allyl carbonate), propylene glycol bis(2-ethylallyl carbonate), 1,3-propanediol bis(allyl carbonate), 1,3-butanediol bis(allyl carbonate), 1,4-butanediol bis(2-bromoallyl carbonate), dipropylene glycol bis(allyl carbonate), trimethylene glycol bis(2-ethylallyl carbonate), pentamethylene glycol bis(allyl carbonate), isopropylidene bisphenol bis(allyl carbonate), oxy bisphenol bis(allyl carbonate), and sulphonyl bisphenol bis(allyl carbonate).

A preferred class of polyol (allyl carbonate) monomers is represented by the general formula,

wherein R0 is hydrogen, halogen or C1 to C4 alkyl, and the average value of m is in the range of from about 1 to about 3. R0 is preferably hydrogen.

Industrially important polyol bis(allyl carbonate) monomers which may be utilized in the present invention include:

Triethylene Glycol bis(Allyl Carbonate)

Diethylene Glycol bis(Allyl Carbonate)

Ethylene Glycol bis(Allyl Carbonate) Diethylene glycol bis(allyl carbonate) is preferred. This monomer is commercially available from PPG Industries, Inc. and is soid under the trademark CR-39 Allyl Diglycol Carbonate.

Because of the process by which the polyol (allyl carbonate) monomer is prepared, i.e., by phosgenation of the polyol (or allyl alcohol) and subsequent esterification by the allyl alcohol (or polyol), the monomer product may contain related monomer species. In the case of diol bis(allyl carbonate), individual related monomer species may be represented by either the general formula:

or the general formula:

wherein R1 is as defined above with respect to graphic formula I, each R3 is independently a divalent radical, derived from a diol, R' is R1 or hydroxyl, s is a whole number from 2 to about 5, and t is a whole number from 1 to about 5.Individual related monomer species associated with diethylene glycol bis(allyl carbonate) may be represented by either the general formula:

or by the general formula:

wherein s is a whole number from 2 to about 5, and t is a whole number from 1 to about 5. Analogous principles apply when the functionality of the polyol is greater than two.

The polyol (allyl carbonate) monomer composition may be purified so as to contain substantially no related monomer species, but this is rarely done. Although the polyol (allyl carbonate) monomer composition may contain only a single related monomer species, it usually contains a mixture of different related monomer species. Typically all of the related monomer species taken together constitute from about 1 to about 20 weight percent of the polyol (allyl carbonate) monomer composition.

As used in the present description and claims, the term polyol (ailyl carbonate) monomer or like names, e.g., diethylene glycol bis(allyl carbonate), are intended to mean and include the named monomer and all related monomer species which may be contained therein.

The liquid polyol (allyl carbonate) polmer which is useful in the practice of the present invention and preparation of the liquid polyol (allyl carbonate) polymer are described in detail in European Patent Specification 0144782.

In accordance with a method of European Patent Specification 0144782 polyol (allyl carbonate) monomer is dissolved in a solvent in which the polymer produced from such monomer is also soluble.

Preferably, the initiator used to conduct the polymerization is also soluble in the solvent. The resulting liquid solution comprising polyol (allyl carbonate) monomer, solvent and preferably initiator is then partially polymerized, e.g., by heating the liquid solution to polymerization temperatures. The polymerization reaction is allowed to continue until from 15 to 50 percent allylic utilization is attained, i.e., until from 15 to 50 percent of the unsaturated carbon - carbon linkages in the monomer are consumed. The degree of allylic utilization can be controlled by regulating the amount of initiator added to the liquid solution, the temperature at which the partial polymerization is performed, and the ratio of solvent to polyol (allyl carbonate). Generally, the greater the amount of initiator used, the higher is the allylic utilization.The higher the temperature of polymerization, the lower is the degree of allylic utilization. At constant temperature and employing a given amount of initiator, the higher the ratio of solvent to monomer, the lower is the degree of allylic utilization. Ordinarily however, if at constant temperature the ratio of solvent to monomer is increased and the amount of initiator employed is also sufficiently increased, the reaction can be driven to a higher degree of allylic utilization without the formation of gel than in a system containing less solvent.

In a preferred embodiment of European Patent Specification 0144782 from about 0.1 to about 1.5 weight percent of initiator, basis the amount of monomer, from about 0.5 to 5 milliliters of solvent per gram of monomer, and polymerization temperatures of from 28"C to about 100 C are used. The degree of allylic utilization can be monitored by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The solvent in the resulting composition can be removed by known techniques, e.g., by evaporation or distillation, leaving a viscous liquid comprising a solution of partially polymerized polyol (allyl carbonate) in polyol (allyl carbonate) monomer. This liquid product is for convenience, referred to herein as "liquid polyol (allyl carbonate) polymer".

The liquid polyol (allyl carbonate) polymer is typically a pourable, syrupy liquid having a kinematic viscosity (measured with a capillary viscometer) of from at least about 100 centistokes to about 100,000 centistokes, typically from about 1000 to 40,000 centistokes, more typically from about 500 to 2,000 centistokes, measured at 25"C., and a bulk density at 25"C. of from about 1.17 to about 1.23 grams per cubic centimeter. The liquid polyol (allyl carbonate) polymer may be further characterized by having more than 12 percent allylic utilization, preferably from at least 15 to 50 percent allylic utilization, and, in a particularly preferred exemplification, from about 20 to 50 percent allylic utilization, as determined by IR or NMR analysis. IR analysis is preferred.

Organic solvents useful in carrying out the solution polymerization are those which are non-reactive chemically with the monomer and resulting polymer, have a boiling temperature substantially below the monomer, i.e., a higher vapour pressure, so as to be easily separated from the monomer by distillation, and which serve as a solvent for the polyol (allyl carbonate) monomer and the resulting liquid polyol (allyl carbonate) polymer (and preferably also the initiator). Useful solvents include the halogenated, e.g., chlorinated, C, or C2 hydrocarbon solvents, e.g., methyl chloride, methylene chloride, ethyl chloride, ethylene dichloride, 1,1,2-trichloro-1,2,2-trifluoroethane, and mixtures thereof.

Methylene chloride is preferred because of its high vapour pressure, low boiling point, ease of separation, and relatively low toxicity.

The amount of solvent used in the partial polymerization process should be sufficient to solubilize all of the monomer and to maintain all of the resulting polymer in solution. This is generally from about 0.5 o 5 milliliters of solvent per gram of monomer. Greater amounts of solvent can be used without deleterious effect. Lesser amounts of solvent result in the formation of an insoluble, infusible intractable gel.

The concentration of initiator useful for the partial polymerization should be sufficient to result in the desired degree of allylic utilization at the conditions used, and generally may vary from 0.1 to about 1.5 weight percent initiator, basis weight of monomer. Greater amounts of initiator may result in either residual initiator in the liquid polyol (allyl carbonate) polymer or formation of an infusible, insoluble, intractable gel.

The initiators useful in carrying out the solution polymerization of the polyol (allyl carbonate) monomer are free radical intiators, e.g., organic peroxides and azo catalysts, and are well known in the art. The preferred free radical initiators are organic peroxy compounds, such as peroxyesters, diacyl peroxides peroxydicarbonates and mixtures of such peroxy compounds.

Examples of peroxy compounds include: peroxydicarbonate esters for example di(n-propyl)-, diisopropyl-, di(n-butyl)-, di(secondary butyl)-, diisobutyl-, di(2-ethylhexyl)-, dicetyl-, dicyclohexyl- and di (4-tertiary-butyl cyclohexyl) peroxydicarbonate; diacyl peroxides for example diacetyl-dibenzoyl-, dilauroyl-, and diisobutyryl peroxide; and peroxyesters for example tertiary-butyl perpivalate, tertiary-butyl peroctoate and tertiary-butyl peroctoate and tertiary-butyl perneodecanoate.

The solution polymerization is generally carried out at temperatures of from about 28"C. to about 100"C., for from about 1 to about 24 hours. The time and temperature depend on the initiator and the concentration thereof, and the solvent: monomer ratio used. For the polymerization of diethylene glycol bis(allyl carbonate) in methylene chloride at a solvent:monomer ratio of 1:1 vlw, with 0.1 to 1.0 weight percent diisopropyl peroxydicarbonate, basis weight of diethylene glycol bis-(allyl carbonate), the time required to obtain the high viscosity, syrupy polymer contemplated is from about 6 to about 18 hours at 60"C.

According to one exemplification, a liquid mixture comprising 100 grams of diethylene glycol bis(allyl carbonate), 300 milliliters of methylene chloride and 1.1 milliliters of diisopropyl peroxydicarbonate was prepared. The liquid mixture was placed in a bottle and the bottle was purged with argon for 3 minutes. The bottle and its contents were held at 70"C for 18 hours and then cooled to 25"C. The liquid reaction mixture was placed in a one-liter round bottom flask and vacuum stripped at 50"C for 2 hours. Then the temperature was raised to 60"C for 1 hour and the pressure lowered until an absolute pressure of 267 pascals was obtained.The residue (viz., liquid polyol (allyl carbonate) polymer) remaining after vacuum stripping was a liquid having a viscosity of 1900 milli Pascals (1900 centipoises) and an allyl utilization of 34 percent.

Although it is not desired to be bound by any theory, it is believed that bromoxylenol blue has tautomeric structures in which the heterocyclic ring may be considered closed or open. Irrespective of whether the heterocyclic ring is closed or open in the compositions of the present invention, it is preferred for chemical nomenclature purposes that bromoxylenol blue be named in closed form.

Closed-form names of bromoxylenol blue are 3', 3"-dibromo-2',2",5',5"tetramethylphenolsulfonephthalein and 2,2'-dibromo-3,3',6,6'-tetramethyl-4,4'-(3H-2,1 -benzoxathiol- 3-ylidene)bisphenol,S,S-dioxide.

The initiators used in the present invention may be widely varied, but in general they are thermally decomposable to produce radical pains. One or both members of the radical pair are available to initiate addition polymerization of allylic groups (and acylic groups when present in the well-known manner.

The preferred initiators are peroxy initiators. Examples of suitable peroxy initiators include those represented by any of the following general formulae:

wherein R4 and R5 are each individually phenyl, phenylalkyl in which the alkyl portion is straight or branched and contains from 1 to about 10 carbon atoms, straight alkyl containing from 1 to about 20 carbon atoms, branched alkyl containing from 3 to about 20 carbon atoms, cycloalkyl containing from about 6 to about 12 carbon atoms, or polycycloalkyl containing from about 7 to about 12 carbon atoms.

The specific groups used for R4 and R5 may be the same or they may be different.

It is to be understood that unless/otherwise qualified, either expressly or contextually, any of the above groups may be substituted with one or more minor substituents so long as their numbers and identities do not render the intiator unsuitable for its intended purpose. Halo groups, alkoxy groups containing from 1 to about 4 carbon atoms, haloalkyl groups containing from 1 to about 4 carbon atoms, and polyhaloalkyl groups containing from 1 to about 4 carbon atoms are examples of substituents which may be used. Alkyl groups containing from 1 to about 4 carbon atoms may be used as substituents on non-aliphatic groups or on non-aliphatic portions of complex groups.

The phenylalkyl groups used for R4, R5, or both R4 and R5 often contain from 1 to about 4 carbon atoms in the alkyl portion. Benzyl and phenylethyl are preferred.

The branched alkyl groups often have at least one branch in the 1-position or the 2-position. In many cases each branched alkyl group contains from 3 to about 8 carbon atoms. Preferably, each branched alkyl group contains 3 or 5 carbon atoms.

Examples of branched alkyl groups that may be used include isopropyl, secondary butyl, isobutyl, tertiary butyl, 1-methylbutyl, 2-methylbutyl, tertiary pentyl, 1,2-dimethylpropyi, neopentyl, 1- methylpentyl, 2-methylpentyl, 1,1 -dimethylbutyl, 1 ,2-dimethylbutyl, 1 3-dimethylbutyl, 2,2- dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, and 1-ethyldecyl. Preferred are secondary butyl, tertiary butyl, and neopentyl.

The cycloalkyl often contains from about 6 to about 8 carbon atoms.

Examples of cycloalkyl groups include cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, and cyclododecyl. Cyclohexyl is preferred.

The polycycloalkyl typically contains from about 7 to about 10 carbon atoms.

Examples of polycycloalkyl groups that may be used include 1-norbornyl, 2-bornyl, and 1adamantyl.

Exemplary peroxy initiators include those described above in respect of the preparation of liquid polyol (allyl carbonate) polymer. Diisopropyl peroxydicarbonate and benzoyl peroxide are the preferred initiators.

Other examples of suitable peroxy initiators include monoperoxycarbonates represented by the following general formula:

wherein R6 is a tertiary C4 or C5 alkyl, e.g., tertiary butyl and tertiary amyl, and R7 is a C3 to C7alkyl.

Examples of alkyl radicals representative of R7 include: isopropyl, n-propyl, isobutyl, secondary butyl, n-butyl, secondary amyl, isoamyl, n-amyl, secondary hexyl, isohexyl, n-hexyl, n-heptyl and 2,4dimethyl-3-pentyl. Preferred as R7 are secondary C3 or C5 C3 to C7 alkyls for example isopropyl, secondary butyl, and 2,4-dimethyl-3-pentyl. Particularly preferred monoperoxycarbonates are tertiarybutylperoxy isopropyl carbonate and teriary-amylperoxy isopropyl carbonate.

The amount of initiator present in the polymerizable composition may be widely varied. Ordinarily the weight ratio of the initiator to the liquid allylic-functional material is in the range of from about 0.5:100 to about 10:100. In many cases the weight ratio is in the range of from about 2:100 to about 8:100. A weight ratio in the range of from about 3:100 to about 7:100 is preferred.

The amount of bromoxylenol blue present in the composition may also be widely varied. Typically the weight/ratio of the bromoxylenol blue to the liquid allylic-functional material is in the range of from about 0.01:100 to about 1:100. In many cases the weight ratio is in the range offrom about 0.05:100 to about 0.8:100. A weight ratio in the range of from about 0.1:100 to about0.5: 100 is preferred.

There are many materials which may optionally be present in the pourable, polymerizable composition. Among these are acrylate additives which may be polyfunctional acrylic monomer and/or monofunctional acrylic monomer.

The polyfunctional acrylate monomers useful as the acrylate additive include those represented by the general formula:

which is the ester of the polyol, R8(OH)1, and an acrylic acid which may be alpha-unsubstituted or alpha-substituted, for example

wherein Rs is hydrogen, halogen, or a C,-C4 alkyl group; RB is the organic residue of the aliphatic polyol, which typically contains from 1 to 12, more typically 2 to 6, carbon atoms, and i is a whole number from 2 to 5, more usually 2 to 3.

In most cases Rg is hydrogen, methyl, or ethyl; hydrogen or methyl is preferred. R8(OH)j can be a diol, a triol, a tetracarbinol, or a pentacarbinol. Most commonly R8(0H)j is a diol ortriol. Typical diols useful in providing esters with terminal diacrylate functionality include: alpha, omega-glycols for example ethylene glycol, trimethylene g lycol, 1,4-buta nediol, 1,5-pentane diol and 1,6-hexanediol, other 1,2-glycols for example propylene glycol, the hydrated ethylene oxide and propylene oxide condensation products for example diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and tetrapropylene glycol.

Preferably the polyfunctional acrylate monomers are the di- or the triacrylates, more preferably the diacrylates.

Suitable triacrylates include trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, glycerol triacrylate, glycerol trimethacrylate, pentaeryth ritol triacrylate, and pentaerythritol trimethacrylate. Suitable tetraacrylates include pentaeryth ritol tetraacrylate and pentaerythritol tetramethacrylate.

Difunctional acrylate monomers are the preferred polyfunctional acrylate monomers. Especially preferred are the diacrylates and dimethacrylates of aliphatic diols. Examples of such diacrylates and dimethacrylates are those represented by the general formulae:

where for any particular compound each Rg is individually hydrogen or methyl, u is a whole number from 1 to 4, vis awhole number from 1 to 4when (C3H60) is

and a whole number from 1 to 3 when (C3H5O) is -CH2CH2CH20-; and w is a whole number from 1 to 12.

Examples of diacrylates include ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, trimethylene glycol diacrylate, trimethylene glycol dimethacrylate, butanediol diacrylate, butanediol dimethacrylate, pentanediol diacrylate, pentanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, di propylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, tetrapropylene glycol diacrylate, and tetrapropylene glycol diethacrylate.

Monofunctional acrylates that can be used in the present invention are typically chosen from C, to C4, preferably C1 or C2 alkyl, and C5 or C6 cycloalkyl, preferably cyclohexyl, esters of the acrylic type acid of general formula XIX, most notably, acrylic acid, methacrylic acid and 2-methylenebutyric acid.

Examples of monofunctional acrylates include: methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, and cyclohexyl methacrylate. The methacrylic acid esters, e.g., methyl methacrylate, are preferred.

The acrylate additive may comprise/only one acrylate compound or it may comprise a plurality of acrylate compounds.

The amount of acrylate additive present in the polymerizable composition may vary widely. When it is used, it is often present in the range of from about 5 to about 20 percent by weight of the liquid allylic-functional material. Frequently, it is present in the range of from about 5 to about 10 percent by weight of the liquid allylic-functional material. However, the amount of the acrylate additive should be low enough that the optical and physical properties of the solid article produced polymerizing the polymerizable composition, such as refractive index and abrasion resistance, are substantially the same as those of a polymerizate prepared from a corresponding polymerizable composition without the acrylate additive.

One or more unsaturated, non-acrylic monomers may optionally be present in the polymerizable composition of the invention. These are often chosen from C1 to C4 alkyl esters of unsaturated dicarboxylic acids, vinyl esters of C1 to C3 saturated monocarboxylic acids and styrene. The unsaturated, non-acrylic monomers, when used, are often present in amounts of from 5 to 20, e.g., 5 to 10, weight percent, basis the liquid allylic-functional material. Examples of such monomers include:C, or C2 alkyl esters of unsaturated C4to C6 dicarboxylic acids. As the unsaturated dicarboxylic acid there can be mentioned maleic, fumaric, itaconic, citraconic, ethylmaleic and mesaconic acids.Alcohols used to prepare the esters of the mono-and dicarboxylic acids include C1 to C4 alkanols, e.g., methanol, ethanol, propanol, isopropanol, the butanols cyclopentanol and cyclohexanol.

Vinyl esters of lower members of monocarboxylic acids can also be used as the unsaturated, non-acrylic monomer. In particular, there are contemplated the vinyl esters of C1 to C3 saturated monocarboxylic acids, e.g., formic, acetic and propionic acids, such as vinyl acetate.

Examples of unsaturated, non-acrylic monomers contemplated herein include: dimethyl maleate, diethyl maleate, methyl ethyl maleate, dimethyl fumarate, diethyl fumarate, methyl ethyl fumarate, vinyl acetate, vinyl formate, vinyl propionate and, styrene. Dimethyl maleate and di methyl fumarate are preferred.

One or more allylic-functional materials which are not polyol (allyl carbonate) compounds (hereinafter referred to as allylic additive), may optionally be present. These include monoallylicfunctional allylic additives for example, allylbenzene, allylcyclopentane, and allylic esters of lower monocarboxylic acids, especially the saturated monocarboxylic acids. Also included are polyallylicfunctional allylic additives for example triallyl isocyanurate and polyallylic functional esters of polycarboxylic acids, especially diallylic-functional esters of dicarboxylic acids; ordinarily such acids are saturated but they may be unsaturated. The amount of allylic additive present in the polymerizable composition may vary widely. When it is used, it ordinarily constitutes from about 1 to about 20 percent by weight of the allylic-functional material present.

Another material which may optionally be present in the pourable, polymerizable composition is mould release agent. When used, the mould release agent is employed in the polymerizable composition in amounts sufficient to ensure an intact, that is, unbroken and uncracked, casting which releases easily from the mould. The mould release agent should be compatible with the pourable, polymerizable composition and not adversely affect the physical properties of the casting. More particularly, the mould release agent should not adversely affect the physical properties most characteristic of the polymerizate such as its rigidity, hardness, index of optical refraction, transmission of visible light and absence of coloring which affects optical clarity. The mould release agent should, therefore, be a liquid or, if a solid, be soluble in the polymerizable composition.

Mould release agents that may be used include alkyl phosphates and stearates. Among the alkyl phosphates that may be used as a mould release agent are the mono and dialkyl phosphates (and mixtures of mono and dialkyl phosphates) which are commercially available from E.l. du Pont de Nemours & Company under the trade names ORTHOLEUM 162 and ZELEC UN. These alkyl phosphates are reported to have straight chain alkyl groups of from 16 to 18 carbon atoms.

Other mould release agents that may be used include stearic acid and the metal salts of stearic acid, e.g., stearic acid salts of the metals zinc, calcium, lead, magnesium, barium, cadmium, aluminium, and lithium. Other fatty acids and fatty acids salts may also be used, provided that they do not adversely effect the physical properties of the casting.

When used, the mould release agent is ordinarily present in the pourable, polymerizable composition in an amount between about 1 and about 2000 parts by weight of mould release agent per million parts by weight of the liquid allylic-functional material (PPM). In many cases, between about 20 and about 200 PPM is used. Between about 25 and about 100 PPM is preferred.

It will be appreciated that the proportions of the bromoxylenol blue and the optional materials and their proportions discussed above in respect of the pourable, polymerizable composition are also applicable to the solution of the bromoxylenol blue in the liquid allylic-functional material.

When the dye consists substantially of only bromoxylenol blue the solution of the dye in the liquid allylic-functional material, the pourable, polymerizable composition, and the resulting polymerizate are all yellow. Indeed yellow polymerizates and their preparation are preferred embodiments of the invention. However, one or more additional dyes may also be incorporated into the solution and/or the polymerizable composition to form a polymerizate of a colour which varies from yellow. The amounts of such optional dye is highly variable and depends upon the effect desired.

The listing of optional ingredients discussed above is by no means exhaustive. These and other ingredients may be employed in their customary amounts for their customary purposes so long as they do not seriously interfere with good polymer formulating practice.

The polymerizable compositions of the invention are usually prepared by admixing the various ingredients. Mixing may be accompanied with heating when it is desirable to hasten dissolution of the bromoxylenol blue or other materials. However, if initiator is present during heating, the temperature should ordinarily be maintained below that at which polymerization is initiated. It is preferred to heat the bromoxylenol blue with all or a portion of the allylic-functional material in the absence of initiator, to cool the resulting solution, and then to introduce the initiator and other ingredients which enter the solution without undue difficulty.

The pourable, polymerizable compositions of the present invention can be polymerized (viz., cured) by the known conventional techniques for polymerizing polyol (allyl carbonate) containing compositions to form solid, crosslinked polymer.

In general, polymerization is accomplished by heating the polymerizable composition to elevated temperatures. Typically polymerization is conducted at temperatures in the range of from about 28"C to about 100"C. In many cases post curing, that is, heating beyond the time thought necessary to substantially fully polymerize the composition is employed. The post cure is often carried out above about 1 OO"C, but below the temperatures at which thermal degredation provides undesirable yellowness, e.g., about 125"C, and preferably for a time sufficient to attain either substantially constant or maximum Barcol hardness.For example, when the cure cycle shown in Table 1 below is followed, the polymerizate may be maintained at 100" for an additional 1 to 4 hours or more. Although not wishing to be bound by any theory, the additional 1 to 4 hours of post cure is believed to decompose, primarily by initiation and chain termination, from 83 percent to 99.9 percent of the peroxide initiator remaining unreacted at the end of the normal 18 hour cure cycle. Moreover, the additional 1 to 4 hours of cure often increases the Barcol Hardness by about 5 to 8 units.

TABLE 1 Time-temperature sequence for benzoyl peroxide cure Cumulative hours Oven temperature, "C 0 63 2 63 4 65 6 67 8 77 10 80 12 85 14 88 16 92 18 100 In most cases, the pourable, polymerizable composition is comformed to the shape of the final solid polymerized article before polymerization. For example, the composition can be poured onto a flat surface and heated, whereby to effect polymerization and form a flat sheet or coating. According to a still further exemplification, the polymerizable composition is placed in moulds as for instance glass moulds, and the molds heated to effect polymerization, thereby forming shaped articles such as lens blanks or ophthalmic lenses. In a particularly preferred embodiment, the composition is poured into a lens mould and polymerized therein to produce an ophthalmic lens.

The invention may be further described with reference to, but in no matter limited to, the following Example.

In the example, fifteen second Barcol hardness was determined in accordance with ASTM Test Method D 2583-81 using a Barcol Impressor, luminous transmission and haze values were determined in accordance with ASTM Test Method D 1003-61 (Reapproved 1967) using a Hunterlab Tristimulus Colorimeter Model D25P-2 employing a collimated Illuminant C standard light source, and 1931 CIE Standard Tristimulus values were determined using the above identified colorimeter in accordance with the accompanying instruction manual. Chromaticity coordinates were calculated from the observed 1931 CIE Standard Tristimulus values as follows: X X Y X+Y+Z' y =X+Y+Z Example Approximately 0.2 to 0.3 part by weight of bromoxylenol blue was dissolved in 100 parts by weight of diethylene glycol bis(allyl carbonate) monomer. The resulting solution had a very dark brilliant yellow color. A pourable, polymerizable composition was formed by admising the above solution and 0.035 parts by weight of diisopropyl peroxydicarbonate. The polymerizable composition was poured into a glass mould constructed of two glass plates separated by a U-shaped pliable gasket that was 3.18 millimeters thick. The glass mould was held together by means of iarge binder clips. After filling the mould with the polymerizable composition, it was placed in a hot air oven and exposed to the Standard Cure Cycle for Diisopropyl peroxydicarbonate shown in Table 2.

TABLE 2 Standard cure cycle for diisopropyl peroxydicarbonate Cumulative hours Oven temperature, "C 0 44 2 46 4 48 6 50 8 54 10 58 12 64 14 69 16 85 17 107(End of Cycle) When the cure cycle was completed, the mould was removed from the oven and allowed to cool to room temperature. The casting, which measured about 15 centimeters x about 15 centimeters by about 3.18 millimeters was removed from the mold and was visually observed to be brilliant yellow in colour. The results of physical and optical testing of the casting are shown in Table 3.

TABLE 3 Luminous Transmission, percent 82.7 Haze, percent 0.9 15 Second Barcol Hardness 21 1931 CIE Standard Tristimulus Values X 73.2 y 82.9 Z 26.5 Chromaticity Coordinates x 0.401 Y 0.454

Claims

1. A solution which comprises (a) liquid allylic-functional material comprising polyol (allyl carbonate) monomer, liquid polyol (allyl carbonate) polymer, or a mixture thereof, and (b) bromoxylenol blue.

2. A solution as claimed in claim 1 in which the liquid allylic-functional material is polyol (allyl carbonate) monomer.

3. A solution as claimed in claim 1 or 2 in which the polyol (allyl carbonate) monomer is represented by the general formula

wherein R1 is allyl or substituted allyl, R2 is a polyvalent radical derived from the polyol, and the average value of n is in the range of from about 2 to about 5.

4. A solution as claimed in claim 1 or 2 in which the polyol (aliyl carbonate) monomer is represented by the general formula:

wherein R0 is hydrogen, halogen or C1 to C4 alkyl, and the average value of m is in the range of from about 1 to about 3.

5. A solution as claimed in claim 1 or 2 in which the polyol (allyl carbonate) monomer is diethylene glycol bis (allyl carbonate) monomer.

6. A solution as claimed in any of claims I to 5 in which the weight ratio of bromoxylenol blue to liquid allylic-functional material is in the range of from about 0.01:100 to about 1:100.

7. A solution according to claim 1 substantially as hereinbefore described with particular reference to the foregoing Example.

8. A pourable, polymerizable composition which comprises (a) liquid allylic-functional material comprising polyol (allyl carbonate) monomer, liquid polyol (allyl carbonate) polymer, or a mixture thereof, (b) bromoxylenol blue, and (c) thermally decomposable polymerization initiator.

9. A pourable, polymerizable composition as claimed in claim 8 in which the liquid allylicfunctional material is polyol (allyl carbonate) monomer.

10. A pourable, polymerizable composition as claimed in claim 8 or 9 in which the polyol (allyl carbonate) monomer is represented by the general formula

wherein R1 is allyl or substituted allyl, R2 is a polyvalent radical derived from the polyol, and the average value n is in the range of from about 2 to about 5.

11. A pourable, polymerizable composition as claimed in claim 8 or 9 in which the polyol (allyl carbonate) monomer is represented by the general formula:

wherein Ro is hydrogen, halogen or C1 to C4 alkyl, and the average value of m is in the range of from about 1 to about 3.

12. A pourable, polymerizable composition as claimed in claim 8 or 9 in which the polyol (allyl carbonate) monomer is diethylene glycol bis(allyl carbonate) monomer.

13. A pourable, polymerizable composition as claimed in any of claims 8 to 12 in which the weight ratio of bromoxylenol blue to liquid allylic-functional material is in the range of from about 0.01:100 to about 1:100.

14. A pourable, polymerizable composition as claimed in any of claims 8 to 13 in which the thermally decomposable polymerization initiator is peroxy initiator.

15. A pourable, polymerizable composition as claimed in claim 14 in which the peroxy initiator is represented by any of the following general formulae:

R400R5

16. A pourable, polymerizable composition as claimed in claim 14 in which the peroxy initiator is diisopropyl peroxydicarbonate or benzoyl peroxide.

17. A pourable, polymerizable composition as claimed in any of claims 8 to 16 in which the weight ratio of bromoxylenol blue to liquid allylic-functional material is in the range of from about 0.5:100 to 10:100.

18. A pourable, polymerizable composition according to claim 8 substantially as hereinbefore described with particular reference to the foregoing Example.

19. A method for the production of a polymerizatee which comprises heating a pourable, polymerizable composition comprising: (a) liquid allylic-functional material comprising polyol (allyl carbonate) monomer, liquid polyol (allyl carbonate) polymer, or a mixture thereof, (b) bromoxylenol blue, and (c) thermally decomposable polymerization initiator, to form a polymerizate.

20. A method as claimed in claim 19 in which the liquid allylic-functional material is polyol (allyl carbonate) monomer.

21. A material as claimed in claim 19 or 20 in which the polyol (allyl carbonate) monomer is represented by the general formula

22. A method as claimed in claim 19 or 20 in which the polyol (allyl carbonate) monomer is represented by the general formula:

23. A method as claimed in claim 19 or 20 in which the polyol (allyl carbonate) monomer is diethylene glycol bis(allyl carbonate) monomer.

24. A method as claimed in any of claims 19 to 23 in which the weight ratio of bromoxylenol blue to liquid allylic-functional material is in the range of from about 0.01:100 to 1:100.

25. A method as claimed in any of claims 19 to 24 in which the thermally decomposable polymerization initiator is peroxy initiator.

26. A method as claimed in claim 25 in which the peroxy initiator is represented by any of the following general formulae:

wherein R4 and R5 each each individually phenyl, phenylalkyl in which the alkyl portion is straight or branched and contains from 1 to about 10 carbon atoms, straight alkyl containing from 1 to about 20 carbon atoms, branched alkyl containing 3 to about 20 carbon atoms, cycloalkyl containing from about 6 to about 12 carbon atoms, or polycycloalkyl containing from about 7 to about 12 carbon atoms.

27. A method as claimed in claim 25 in which the peroxy initiator is diisopropyl peroxydicarbonate or benzoyl peroxide.

28. A method as claimed in any of claims 19 to 27 in which the weight ratio of initiator to liquid allylic-functional material is in the range offrom about 0.5:100 to 10:100.

29. A method according to claim 19 substantially as hereinbefore described with particular reference to either of the foregoing Examples.

30. A polymerizate whenever produced by a method as claimed in any of claims 19 to 29.