MXPA00006515A - Process for forming poly(allyl carbonate)-functional prepolymer composition - Google Patents

Abstract

A process for forming a polymerizable, liquid, substantially gel-free, poly(allyl carbonate)-functional prepolymer composition comprises heating a neat composition comprising at least one poly(allyl carbonate)-functional monomer and free radical initiator having a ten-hour half-life temperature of at least 85°C at temperatures in the range of from 5 Celsius degrees below the ten-hour half-life temperature of the free radical initiator to 150°C, to form a reaction mixture having an increased 25°C viscosity in the range of from 25 to 10,000 centipoises and an ethylenic double bond utilization of at least 3 percent;and over a period of less than 90 minutes cooling the reaction mixture to a temperature at least 20 Celsius degrees below the ten-hour half-life temperature of the initiator.

Description

PROCESS FOR FORMING COMPOSITIONS OF PREPOLIMERO WITH FUNCTION POLI (ALIL CARBONATO) BACKGROUND OF THE INVENTION Polymer (allyl carbonate) monomer compositions are polymerized using free radical initiators to produce hard polymers. Many of these polymers are substantially transparent to visible light, are substantially colorless, have refractive indices of 1.45 to 1.6, and possess a Barcol hardness above zero. For these reasons, said monomer compositions find application as precursors for transparent coatings, optical lenses, optical lens plates and other optical elements, as well as flat or curved transparent sheets. The light transmission characteristics can be altered by incorporating in the monomer composition dyes, light absorbing compounds, pigments and the like, prior to polymerization, or by dyeing the polymer. A problem associated with the polymerization of monomer compositions with poly (allyl carbonate) function is the relatively high shrinkage of the material that occurs during the course of the polymerization until the final thermoset polymer is obtained. For example, a shrinkage of about 13 percent occurs during the polymerization of diethylene glycol bis (allyl carbonate). These high contractions are particularly detrimental in molding operations such as those used to produce ophthalmic lenses and plates for ophthalmic lenses into which the liquid monomer composition is introduced into a mold and then polymerized into the final thermoset polymer. Although there is no intention to establish a theory, it is believed that the shrinkage is mainly due to a reduction in the volume associated with the conversion of the allylic groups into polymer units. It is known that it is possible to reduce shrinkage in the mold by introducing a liquid prepolymer into the mold and then polymerizing the prepolymer to the final thermoset polymer. Typically, the prepolymer is obtained by partial polymerization of the monomer composition with poly (allyl carbonate) function to consume a portion of the allylic groups. However, partial polymerization is stopped before significant gelation takes place, so that the prepolymer can be introduced into the mold as a liquid. Although the principle is solid, difficulties have been encountered in achieving an acceptable result in practice. There is a method which consists in carrying out the prepolymerization in the presence of a substantially inert organic solvent, checking the completion of the reaction and then removing the solvent by distillation. See, for example, the following patents: US 4613656, US 4686266, US 4959429, US 4959433, US 5017666 and JP 61 (1986) -64706. The elimination of the solvent takes time, it is expensive and in cases where the solvent is toxic or flammable, it is dangerous. In general, it is difficult to remove the last amounts of solvent without introducing an unsatisfactory color to the prepolymer. Another method is to carry out the prepolymerization in a net system, i.e., a system substantially free of inert solvent, using initiators having half-life temperatures of ten low hours. See, for example, the following patents: US 4590248; US 4623708; JP 51 [1976] -9188; JP 57 [1982] -26521; JP 57 [1982] -133106; JP 61 [1986] -51012 and JP 05 [1993] -29664. With this method, once the desired viscosity is reached, or when it is about to be reached, the reaction mixture is cooled to stop the reaction. If the low-temperature initiator of half-life of ten hours has not been consumed, the storage stability of the prepolymer product is insufficient. To address the problem, attempts have been made to regulate the amount of initiator, the reaction temperature and other variables, so that upon cooling the reaction to stop the polymerization, the low-temperature initiator having a half-life of ten hours was consumed and the viscosity of the prepolymer was maintained at the desired value. This mode of operation is not practical since the number of variables to be controlled is so extensive that obtaining the desired viscosity of the prepolymer product on a reproducible basis is difficult. A process which is relatively easy to control and which can be used to consistently obtain prepolymer products with viscosities within reasonably tight specification ranges has now been discovered. The prepolymer products are polymerizable, liquid, substantially gel-free and substantially stable in storage at ordinary room temperature. Accordingly, the invention consists in a process for forming a poly (allyl carbonate) polymer-free prepolymer composition, liquid, polymerizable, consisting of (a) heating a net composition including at least one poly-functional monomer (allyl carbonate) and a free radical initiator having a half-life of ten hours of at least 85 ° C at temperatures between 5 degrees Celsius below the ten-hour half-life of the free radical initiator and 150 ° C, to form a reaction mixture having a higher viscosity at 25 ° C within the range of 25 to 10,000 cps (25 to 10,000 milliPascal second (mPa.s)) and an ethylene double bond utilization of at least one 3 percent; and (b) for a period of less than 90 minutes, cooling the reaction mixture to a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator. Since the process is solvent-free, the hazards associated with the handling of solvents are eliminated and a step for solvent removal is not required. Since the initiator has a high half-life temperature of ten hours and is stable at normal room temperature, the prepolymer product is stable at normal room temperature despite the presence of initiator residues. Since it is not necessary to completely consume the initiator, the process is relatively firm in terms of variations in the concentration of the initiator. A product with a specific viscosity specification at 25 ° C (for example 110-120 cps) can be consistently obtained by monitoring the viscosity of the reaction mixture during the partial polymerization process. For short, primers with half-life temperatures of at least 85 ° C for 10 hours will be referred to as "high-temperature initiators" and initiators that have half-life temperatures of 10 hours at minus 85 ° C will be called "low-temperature initiators". temperature". The net composition that is heated includes at least one monomer with poly (allyl carbonate) function. In most cases the net composition includes a mixture of poly (allyl carbonate) monomers. Poly (allyl carbonate) monomers which can be used in the practice of the present invention are liquid poly (allyl carbonates) of polyhydroxy organic materials. Examples of such monomers include poly (allyl carbonates) of linear or branched aliphatic polyalcohols, poly (allyl carbonates) of polyalcohols containing cycloaliphatic groups, and poly (allyl carbonates) of polyhydroxy compounds containing aromatic groups. The monomers are known per se and can be prepared by methods well known in the art. See, for example, US patents. No. 2,370,567; 2,403,113; 2,455,652; 2,455,653; 2,587,437; 4,144,262; and 4,742,133. In one of the methods, the appropriate allylic alcohol is reacted with phosgene to form the corresponding alkyl chloroformate which is then reacted with the desired polyhydroxy organic material. In another method, the polyhydroxy organic material is reacted with phosgene to form organic polychloroformate which is then reacted with the appropriate allyl alcohol. In a third method, the polyhydroxy organic material, the appropriate allyl alcohol and phosgene are mixed and reacted. In all these reactions, the proportions of the reactants are approximately stoichiometric, with the exception that a substantial excess of phosgene can be used if desired. The temperatures of the chloroformate formation reactions are preferably below 100 ° C in order to minimize the formation of unwanted side products. Normally, the chloroformate formation reaction is within the range of 0 ° C to 20 ° C. Normally, the carbonate formation reaction is carried out at about the same temperature although higher temperatures may be employed. Among suitable acid acceptors, if desired, for example, pyridine, tertiary amine, alkali metal hydroxide or alkaline earth metal hydroxide may be used. Many of the poly (allyl carbonate) monomers can be represented by the formula (1): Formula (1) where R x is the group derived from the unsaturated alcohol and is an allyl group or substituted with allyl, R 2 is the organic group derived from the polyhydroxy organic material, and the average value of n lies within the range of 2 to 5, preferably 2. For any particular compound, the value of n is an integer. In contrast, for mixtures of compounds, the mean value of n can be an integer or a fractional number. The average value of n depends on the molecular weight of the number average of the poly (allyl carbonate) monomer species constituting the mixture. The allyl group (R) can be substituted at the 2-position with a halogen, preferably chlorine or bromine, or an alkyl group containing from 1 to 4 carbon atoms, generally a methyl or ethyl group, The group R can be represented by the formula (2): Formula (2) where R0 is hydrogen, halo or an alkyl group containing from 1 to 4 carbon atoms. Specific examples of Rx include allyl, 2-chloroallyl, 2-bromoalyl, 2-fluoroalyl, 2-methallyl, 2-ethylallyl, 2-isopropylallyl, 2-n-propylallyl and 2-n-butylallyl groups. Most commonly, Rt is the allyl group, H2C CH CH2- R2 is a polyvalent group derived from the polyhydroxy organic material which may be an aliphatic polyalcohol or a compound containing aromatic groups and polyhydroxy function containing 2, 3, 4 or 5 groups hydroxy. Typically, the polyhydroxy organic material contains 2 hydroxy groups, such as, for example, a glycol or bisphenol. The aliphatic polyalcohol can be linear or branched and contains from 2 to 10 carbon atoms. Commonly, the aliphatic polyalcohol is an alkylene glycol having from 2 to 4 carbon atoms or a poly (C2-C4) alkylene glycol, such as, for example, ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol or diethylene glycol, triethylene glycol , etc. A class of compounds containing aromatic groups and polyhydroxy function can be represented by the formula (3): Formula (3) wherein each R3 is independently alkyl containing 1 to 4 carbon atoms, phenyl, or halo; the value of each a is independently within the range of 0 to 4; each Q is independently oxy, sulfonyl, alkanediyl having 2 to 4 carbon atoms, alkylidene having 1 to 4 carbon atoms; and the value of q is within the range of 0 to 3. Preferably, Q is 1-methylethylidene, ie, isopropylidene. Preferably, the value of q is zero, in which case one of the subclasses is represented by the formula (4): Formula (4) where each R3, each a and Q are as mentioned in relation to formula (3). Preferably, the two hydroxyl groups are in the ortho or para positions. The positions for are especially preferable. The preferred aromatic group and polyhydroxy functional group compound is represented by the formula (5): CH, CH, Formula (5) The polyhydroxy organic material from which R3 is derived may also consist of extended chain compounds with polyhydroxy function. Examples of such compounds based on an alkylene oxide extension include extended trimethylolpropane with ethylene oxide, extended trimethylolpropane with propylene oxide, extended glycerol with ethylene oxide and extended glycerol with propylene oxide. Additional examples include bisphenols extended with ethylene oxide as, for example, those represented by the formula (6) < R3 > a < R3 > Formula a (6) where Q, R3 are already as indicated above in relation to formula (3) and j and 'k are each independently 1, 2, 3 or 4. Many of the compounds that are based on lactone extension are described in US patent No. 3,169,945. Specific examples of the radical R3 include alkylene groups containing from 2 to 10 carbon atoms such as ethylene, (-CH2-CH2-), trimethylene, methylethylene, tetramethylene, ethylethylene, pentamethylene, hexamethylene, 2-methylhexamethylene, octamethylene and decamethylene. , alkylene ether groups such as -CH2OCH2-, -CH2CH3OCH2CH2-, -CH20CH2CH2- and -CH2CH2CH3OCH3CH2CH2-, alkylene polyether groups such as -CH3CH2OCH2CH2OCH2CH2- and -CH2CH2CH3OCH2CH2CH2OCH3CH2CH2-; alkylene carbonate and alkylene ether groups. carbonate such as -CH2CH2OC (O) OCH3CH3- and -CH2CH2OCH3CH3OC (0) OCH2CH2OCH2CH2-; and l-methylethylidene-4, 1-phenylene. More commonly, R2 is -CH2CH2-, -CH2CH2OCH3CH3-, or -CH2CH3OCH2CH2OCH3CH2-. Specific examples of poly (allyl carbonate) functional monomers useful in the practice contemplated herein include bis (2-chloroalyl carbonate) of ethylene glycol, bis (allyl carbonate) of ethylene glycol, bis (allyl carbonate) ) of 1,4-butane diol, bis (allyl carbonate) of 1,5-pentanediol, bis (allyl carbonate) of 1,6-hexanediol, diethylene glycol bis (2-methallyl carbonate), diethylene bis (allyl carbonate) glycol, bis (allyl carbonate) of triethylene glycol, bis (2-ethylallyl carbonate) of propylene glycol, bis (allyl carbonate) of 1,3-propanediol, bis (allyl carbonate) of 1,3-butanediol, bis (2-) bromoalyl carbonate) of 1,4-butanediol, bis (allyl carbonate) of dipropylene glycol, bis (2-ethylallyl carbonate) of trimethylene glycol, bis (allyl carbonate) of pentamethylene glycol, bis (allyl carbonate) of isopropylidene bisphenol, bis ( allyl carbonate) of oxybisphenol, bis (allyl carbonate) of bisphenol sulfonyl and the tris (allyl carbonate) of tris (2-hydroxyethyl) isocyanur ato. A preferable class of monomers with poly (allyl carbonyl) function is represented by formula (7): R0 O O R0 CH2 CCH20 3CC? 04-j - CCHH22-CCHH22004 «--- CCOOCCHH22CC == - CCH2 m Formula (7) where R 0 is hydrogen, halo or C 1 -C 4 alkyl and the average value of m lies within the range of 1 to 3. R 0 is preferably hydrogen. Bis (allyl carbonate) of diethylene glycol is preferred. PPG Industries, Inc. distributes this monomer on the market as CR-39® Allyl Diglycol Carbonate. Due to the process by which the poly (allyl carbonate) monomer is prepared, the monomer compositions typically include a mixture of poly (allyl carbonate) functional compounds represented by the formula (8): Rx * ~ O Rj.

Formula (8) or formula (9) Formula (9¡ where R1 is as defined above in relation to formula (1), each R4 is independently a divalent group derived from a dihydroxy organic compound, R 'is Rx or hydroxyl, s is a positive integer, and t is a positive integer. Analogous principles are applied when the functionality of the polyhydroxy organic material is greater than two. The bis (allyl carbonate) monomer compositions of diethylene glycol usually include a mixture of diethylene glycol compounds (allyl carbonate) represented by the formula (10): OCH, CH-CH2 Formula (10) or by formula (11) H OCH, CH2OCH2CH2OC-OCH, CH = CH, Formula (11) where s is a positive integer and t is a positive integer. The diethylene glycol compound (allyl carbonate) for which the value of s is 1 usually constitutes 25 to 99 percent of the area of the mixture of the compounds (allyl carbonate) of diethylene glycol. Frequently, the (allyl carbonate) of diethylene glycol for which the value of s is 1 constitutes from 25 to 95 percent of the area of the mixture of the compounds (allyl carbonate) of diethylene glycol. As used herein and in the claims, the relative amounts, expressed as a percentage of area, of the diethylene glycol (allyl carbonate) compounds having different values of s are determined by high performance liquid chromatography using an instrument equipped with a DuPont Zorbax Sil column operating at a temperature of approximately 15 ° C, a refractive index detector and employing a mobile phase composition of 40% methylene chloride / 25% ethyl ether / 25% ethyl ether saturated with water / n -hexane at 10%, said percentages being expressed as percentages in volume. A subclass of particular interest is a mixture of diethylene glycol compounds (allyl carbonate) represented by formula (10) or formula (11), in which the compound (allyl carbonate) for which the value of s is 1 constitutes from 82 to 95 percent of the area of the mixture of the compounds (allyl carbonate) of diethylene glycol. Another subclass of particular interest is a mixture of diethylene glycol compounds (allyl carbonate) represented by formula (10) or formula (11) in which the compound (allyl carbonate) for which the value s is 1 constitutes 25 to 75 percent of the area of the mixture of the compounds (allyl carbonate) of diethylene glycol. Preferably, the mixture of diethylene glycol compounds (allyl carbonate) represented by formula (10) or formula (11) is prepared by reacting bischloroformate of diethylene glycol with an allyl alcohol and, optionally, diethylene glycol, in the presence of an acceptor of suitable acid, such as, for example, pyridine, a tertiary amine, or an alkali metal or alkaline earth metal hydroxide. Frequently, it is convenient to use a 50% by weight solution of sodium hydroxide in water as an acid acceptor. A substantially inert water-insoluble organic diluent can optionally also be used. The combined amounts of allyl alcohol and diethylene glycol employed are at least sufficient for their reaction with substantially all of the diethylene glycol bischloroformate. An increase in the ratio of the number of moles of diethylene glycol to the number of moles of diethylene glycol bischloroformate results in a decrease in the percentage of the area of the compound (allyl carbonate) of diethylene glycol represented by the formula (10) in which is 1, together with the corresponding increase in the percentage of the area of the compounds represented by the formula (10) in which s is greater than l. The ratio of the number of moles of diethylene glycol to the number of moles of diethylene glycol bischloroformate is generally in the range of 0 to 0.9: 1. The base is slowly added to the reaction medium containing the bischloroformate of diethylene glycol, allyl alcohol and diethylene glycol, while external cooling is applied in order to control the reaction temperature, frequently within the range of 0 ° C to 25 ° C. Once all of the chloroformate groups have reacted substantially, removal of the aqueous phase is usually preferable. If desired, the organic phase can be washed with water in order to remove the inorganic by-products and purify it under vacuum to remove water, solvent and other volatile materials. The poly (allyl carbonate) monomer composition can be purified so that it contains essentially no related monomer species, but is rarely made. Although the poly (allyl carbonate) monomer composition may contain only a single species of related monomer, it usually contains a mixture of different related monomer species. Typically, all the related monomer species taken together constitute from 1 to 75 weight percent of the poly (allyl carbonate) monomer composition. Frequently, all the related monomer species taken together constitute from 5 to 75 weight percent of the poly (allyl carbonate) monomer composition. In many cases, all the related monomer species taken together constitute from 5 to 18 weight percent of the poly (allyl carbonate) monomer composition. In other cases, all the related monomer species taken together constitute from 25 to 75 weight percent of the poly (allyl carbonate) monomer composition. As used in the present description and claims, the term monomer with poly (allyl carbonate) function, or similar names, eg, bis (allyl carbonate) of diethylene glycol, is meant to include and include the named monomer and all the related monomer species that may be contained. There are many materials that can optionally be present in the liquid poly (allyl carbonate) monomer composition employed in the process of the invention. Among them, optional ethylenically unsaturated compounds can be mentioned. As used herein and in the claims, "optional ethylenically unsaturated compound" refers to an ethylenically unsaturated compound that is not a compound having a poly (allyl carbonate) function. The optional ethylenically unsaturated compound can be an optional polyethylenically unsaturated compound or it can be an optionally monoethylenically unsaturated compound. When two or more optional ethylenically unsaturated compounds are present, they may be optional polyethylenically unsaturated compounds, optionally monoethylenically unsaturated compounds or a mixture of one or more optional polyethylenically unsaturated compounds and one or more optional monoethylenically unsaturated compounds. Other optional compounds that may be present include compounds that are devoid of (allyl carbonate) groups but that contain various allyl groups. Examples thereof include 2,4,6-tris (allyloxy) -1,3,5-triazine [CAS 101-37-1], triallyl-3,5-triazine-2,4,6 (lH, 3H, 5H) -trione [CAS 1025-15-6], diallyl phthalate [CAS 131-17-9], triallyl trimellicate [CAS 2694-54-4], and triallyl trimesate [CAS 17832-16-5 ] Polymerizable polyethylenically unsaturated compounds not containing allyl groups may optionally be present. These include the bis (acrylates) and bis (methacrylates) of diols, the tris (acrylates) and tris (methacrylates) of triols and the tetrakis (acrylates) and tetrakis (methacrylates) of tetraalcohols. Examples of suitable diols include HOCH2CH2OCH2CH2OH and the diols represented by the formula (12) HO - A - OH Formula (12) The divalent radical A can be aliphatic, aromatic or include both aliphatic and aromatic portions. Examples include alkanediyl groups containing from 2 to 10 carbon atoms such as 1,2-ethanediyl, 1,3-propanediyl, 2,2-dimethyl-1,3-propanediyl, 1-methyl-1,2-ethanediyl. , 1,4-butanediyl, 1-ethyl-l, 2-ethanediyl, 1,5-pentanediyl, 1,6-hexanediyl, 2-ethyl-l, 6-hexanediyl, 1,8-octanediyl and 1,10-decanediyl . Other examples include alkylene ether groups such as -CH2OCH3-, -CH2CH2CH2OCH2CH2CH2- and -CH2OCH2CH3-. Other examples include alkylene polyether groups such as -CH2CH2OCH2CH2OCH2CH2- and -CH2CH2CH2OCH2CH2CH2-OCH2CH2CH2. Further examples include alkylene carbonate groups such as -CH2CH2OC (0) OCH2CH2- and alkylene ether carbonate groups such as -CH2CH2OCH2CH2OC (0) OCH2CH2-. Examples of cycloaliphatic groups include 1,3-cyclopentanediyl, 1,3-cyclohexanediyl, 1,4-cyclohexanediyl and 1,5-cyclooctanediyl. Examples of aromatic groups include 1,3-phenylene and 1,4-phenylene. Examples of groups containing both aliphatic and aromatic moieties include 2-methyl-1,4-phenylene, 2,6-dimethyl-1,4-phenylene, methylene-di-4,1-phenylene, 1-methylethylidene. di-4, l-phenylene, 1-methylethylidenebis [2,6-dibromo-4,1-phenylene], 1-methylethylidenebis [2,6-dichloro-4,1-phenylene], 1-methylpropylidene-di-4, 1-phenylene, 1-methylethylidenebis [2-methyl-4,1-phenylene], 1,2-ethanediyl-di-4,1-phenylene, methylene-di-2, l-phenylene, 1-methylethylidenebis [2- ( 1-methylethyl) -4, 1-phenylene], 1,3-phenylenebis (l-methylethylidene-4,1-phenylene], 1,4-phenylenebis [1-methylethylidene-4,1-phenylene, sulfonyl-di-4 , l-phenylene, cyclohexylidene-di-4, l-phenylene, l-phenylethylidene-di-4,1-phenylene, ethylidene-di-4, l-phenylene, propylidene-di-4,1-phenylene, l-ethylpropylidene -di-4, l-phenylene, 1,4-cyclohexanediyl-di-4, l-phenylene, 1,3-cyclohexanediyl-di-4,1-phenylene, 1,2-cyclohexanediyl-di-4,1-phenylene and thio-di-4,1-phenylene Examples of suitable triols include 1, 1, 1 -trimethylolpropane, 1,2,3-propanetriol and tris (2-hydroxyethyl) isocyanurate. Suitable examples of tetraalcohols include pentaerythritol and erythritol. The half-life of the free radical initiator at any specified temperature is defined as the time period in which the initiator loses half of its activity. It is determined through studies of the decomposition kinetics of the initiator. See, for example, the Peroxide Selection Based on Half -life product bulletin, Atochem North America, Organic Peroxides Division, Buffalo, New York (1989); and Orville L. Magelli and Chester S. Sheppard, Organic Peroxides, Volume I, Daniel Swern, ed. , Wiley-Interscience, New York, pages 81-87 (1970). The ten-hour half-life of an initiator is the temperature at which half of the originally present initiator decomposes in 10 hours. Accordingly, the half-life temperature provides a useful and effective guide for the selection of primers for specific formulations and treatment conditions. For the partial polymerization of a monomer composition with poly (allyl carbonate) function, any conventional free radical initiator, especially peroxide initiators, can be used with a suitable average life of ten hours. Initiators suitable for use in the present invention have a half-life of ten hours of at least 85 ° C. The half-life temperature of ten hours is normally within the range between 85 ° C and 135 ° C. Frequently, it is within the range of 90 ° C to 120 ° C. It is preferable from 95 ° C to 105 ° C. There are many initiators of this type, although the preferred initiator is OO-tert-butyl-0- monoperoxycarbonate. { 2-ethylhexyl} [CAS 34443-12-4], which has a half-life of ten hours at 100 ° C. Other examples of initiators that may be used include OO-tert-butyl O-isopropyl monoperoxycarbonate [CAS 2372-21-6] and OO-tert-amyl O- monoperoxycarbonate. { 2-ethyl hexyl] having a half-life of ten hours at 99 ° C. High temperature initiator mixtures that have the same half-life temperatures of ten hours can be used, or different, when desired. If the half-life temperatures of ten hours are the same, the same principles apply as when using a single high-temperature initiator. If the half-life temperatures are different, it is preferable to use a non-isothermal reaction temperature profile that increases continuously or discontinuously. The highest temperature in the last reaction stages should be high enough to consume at least part of the initiator having the half-life temperature of ten hours higher. Also, mixtures of at least one high temperature initiator and at least one low temperature initiator can be used. In this case, it is preferable to use the lower reaction temperatures during the first part of the reaction until the low temperature initiators are mostly consumed. The purpose of using the high temperature initiator is to ensure that the product liquid prepolymer composition will be stable at ambient temperatures even though the high temperature initiator is present without being consumed. Therefore, it is preferable that the low temperature initiator, or not present, be present in the product liquid prepolymer composition which could result in product instability at room temperature. The amount of high temperature initiator that is present in the net composition can vary within a wide range. Typically, the amount of high temperature initiator employed is comprised between 10 and 2500 parts of initiator per million parts of monomer, by weight. Frequently, the amount used is between 25 and 1200 parts of initiator per million parts of monomer, by weight. It is preferable from 25 to 600 parts per million by weight.

It is especially preferable from 25 to 200 parts by weight per million. As the polymerization progresses, the concentration of the initiator usually decreases. Incremental additions of the initiator are contemplated during the polymerization. The monomer that includes at least one monomer with a poly (allyl carbonate) function is partially polymerized by heating a net composition which initially includes the monomer and a high temperature initiator at a temperature in the range of 80 ° C to 150 ° C. In many cases, the temperature is within the range of 5 degrees Celsius below the ten-hour average life temperature of the high temperature peroxide initiator at 30 degrees Celsius above the half-life temperature of ten hours. Preferably, the temperature is within the range between the half-life temperature of ten hours of the initiator and 10 degrees Celsius above the half-life temperature of ten hours. The net composition can optionally be sprayed with a non-reactive gas in order to remove substantially all of the dissolved oxygen. The net composition is usually sprayed with a non-reactive gas during the entire time it is heated. The flow rate of the non-reactive gas is usually at least 0.01 reactor volume per minute. Normally, the flow rate is within the range between 0.01 and 5 of the reactor volume per minute. Frequently, it is within the range of 0.03 and 2 of the reactor volume per minute. It is preferable to 0.05 to 1 of the reactor volume per minute. Examples of non-reactive gases that can be used to spray the net composition include helium, argon, nitrogen or a mixture of two or more of them. The most frequent is to spray the net composition with commercially pure nitrogen. The net composition can remain at rest or can be stirred at the same time that the aforementioned temperature is maintained. Generally, the agitation of the net composition provided by the bubbles in elevation of the nitrogen or other non-reactive gas used for the spraying is sufficient, although it is preferable to use additional agitation as is provided by shovels, agitators, mixers, pumps or other devices Similar. When the net composition is heated and the polymerization proceeds, its viscosity increases at 25 ° C. The net composition is heated to form a reaction mixture having a viscosity at 25 ° C in the range of 25 to 10,000 cps (25 to 10,000 mPa.s) and the use of a double ethylenic bond of at least 3 per cent. hundred. Next, the reaction mixture is cooled for a period of less than 90 minutes at a temperature of at least 20 degrees Celsius below the temperature of the ten-hour half-life of the initiator. Frequently, the reaction mixture has a viscosity at 25 ° C in the range of 45 to 3000 cps (45 to 3000 mPa.s) when cooling starts at a temperature of at least 20 degrees Celsius below the temperature of life average of ten hours of the initiator. Frequently, the reaction mixture has a viscosity at 25 ° C in the range of 60 to 1000 cps (60 to 1000 mPa.s) when said cooling starts. In many cases the reaction mixture has a viscosity at 25 ° C in the range of 75 to 400 cps (75 to 400 mPa.s) when cooling begins. In some cases, the reaction mixture has a viscosity at 25 ° C in the range of 80 to 120 cps (80 to 120 mPa.s) when cooling begins. In other cases, the reaction mixture has a viscosity at 25 ° C in the range of 200 to 350 cps (200 to 350 mPa.s) when said cooling begins. As used herein, viscosity at 25 ° C of a reaction mixture or composition substantially free of gel, liquid, polymerizable, is determined according to test method D 2393-86 of ASTM. Frequently, the reaction mixture has a double ethylenic bond utilization in the range of 3 to 16 percent when cooling begins at a temperature of at least 20 degrees Celsius below the ten-hour half-life of the initiator. Frequently, the reaction mixture has a double ethylenic bond utilization in the range of 6 to 14 percent when said cooling starts. Preferably, the reaction mixture has a double ethylenic bond utilization in the range of 8 to 12 percent when cooling begins at a temperature of at least 20 degrees Celsius below the ten-hour half-life of the initiator. As used herein and in the claims, the use of the double ethylenic linkage of a reaction mixture or a substantially liquid, polymerizable, gel-free composition is the total percentage of double ethylenic linkages available from the monomer that are consumed in forming the prepolymer. . The use of the double ethylenic bond is determined by iodometric titration in the manner indicated below. One gram of a heavy sample is introduced with the highest precision at 0.0001 grams in a 250 milliliter Erlenmeyer flask and 50 milliliters of chloroform are added to dissolve the sample. 20 milliliters of a 0.5 molar solution of iodine monochloride in acetic acid are added. The flask is covered and stored in the dark for one hour. Then, 50 milliliters of a 1.8 molar aqueous solution of potassium iodide is added and the titration is started with a standard 0.5 sodium standard thiosulfate solution with vigorous stirring. The titration is continued until the yellow color disappears. The assessment should be carried out slowly when approaching the end point to avoid overvaluation. Likewise, a blank sample is evaluated in the same way. The iodine number of both the partially polymerized monomer and the initial monomer that is not partially polymerized is calculated as follows: I = (Tb - TJ (N) (12.692) / W where: I is the iodine value expressed in grams of I2 per 100 grams of sample, Tb is the blank sample titration expressed in milliliters of thiosulfate solution sodium, Ta is the titration of the sample expressed in milliliters of sodium thiosulfate solution, N is the normality of the sodium thiosulfate solution and is the mass of the sample expressed in grams.The use of the double ethylenic bond is calculated as follows where: U is the double ethylenic bond expressed as a percentage;? is the iodine number of the initial monomer that has not been partially polymerized expressed in grams of I2 per 100 grams of the sample, and Ip is the iodine value of the partially polymerized monomer expressed in grams of I2 per 100 grams of sample The cooling period at a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator is fr consistently less than 1 hour. A cooling period at a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator of 30 minutes or less is preferable. The mixture is then cooled to room temperature at the convenient speed. During cooling, the viscosity of the reaction mixture increases somewhat, the magnitude of which depends on the reactivities of the initiator and ethylenically unsaturated compounds, the initial and final temperatures and the cooling rate.

The prepolymer product is substantially stable in storage at normal room temperature. Frequently, the substantially polymer-free liquid gel composition produced through the process of the invention has a viscosity at 25 ° C of 10,000 cps or less. In many cases, the viscosity at 25 ° C is 3000 cps or less. Frequently, the viscosity at 25 ° C is 1000 cps or less. Preferably, the viscosity at 25 ° C is 400 cps or less. More preferably, the viscosity at 25 ° C is 125 cps or less. The substantially polymer-free liquid gel composition produced through the process of the invention has a double ethylenic bond utilization of at least 3 percent. Frequently, the use of the double ethylenic bond is within the range of 3 to 16 percent. It is preferable from 6 to 14 percent. It is especially preferable from 8 to 12 percent. In most cases, the substantially gel-free, liquid polymerizable composition of the invention is molded into the solid polymerized article form desired prior to polymerization to form said article. For example, the substantially gel-free, liquid, polymerizable composition can be poured onto a flat surface and polymerized to form a flat sheet or for coating. According to yet another example, the composition is substantially free of gel, liquid, polymerizable in molds, such as for example glass molds, and is polymerized to form molded articles as a primer of lenses or lenses. This method is particularly advantageous for the preparation of ophthalmic lens and ophthalmic lens blanks. The substantially gel-free, liquid, polymerizable composition of the invention can be polymerized to a thermoset state by conventional techniques for the polymerization of formulations containing (allyl carbonate). In one embodiment, the polymerization is carried out by heating the polymerizable formulation containing free radical initiator at elevated temperatures. Normally, heating is carried out in an oven or in a bain-marie. Typically, polymerization is carried out at a temperature within the range of 28 ° C to 130 ° C. In many cases, post-curing is employed, that is, heating beyond the time considered necessary to substantially polymerize the formulation. The post-curing is carried out frequently at temperatures around the maximum temperature of the curing cycle, or above it, but below temperatures at which thermal degradation produces undesirable yellowing, preferably, for a period of time sufficient to obtain a substantially constant or maximum Barcol hardness. In most cases, post-curing is carried out at temperatures within the range of 100 ° C to 130 ° C. The initiators that can be used in the present invention to polymerize the substantially gel-free, liquid, polymerizable composition can be very varied, but in general they are thermally decomposable to produce pairs of radicals. One or both members of the radical pair are available to initiate addition polymerization of ethylenically unsaturated groups according to the known manner. Preferred initiators are peroxy initiators. In the US patent No. 4,959,429, many suitable peroxy initiators are described. Preferred initiators include diisopropyl peroxydicarbonate [CAS 105-64-6], benzoyl peroxide [CAS 94-36-0], tert-butylperoxy isopropyl carbonate [CAS 2372-21-6] and tere-amyl carbonate. peroxy isopropyl [CAS 2372-22-7]. When used, the amount of initiator present in the substantially gel-free, liquid, polymerizable composition of the invention can be varied. Normally, the weight ratio between the initiator and all the ethylenically unsaturated material present in the substantially liquid, polymerizable, gel-free composition is within the range of 0.3: 100 to 7: 100. In many cases, the weight ratio is in the range of 0.5: 100 to 5: 100. The initiator can be incorporated into the composition substantially free of gel, liquid, polymerizable by mixing it with other components. Those skilled in the art will recognize that the most preferable weight proportions of the initiator will depend on the nature of the initiator used, as well as on the nature and proportions of the various ethylenically unsaturated materials present in the substantially liquid, polymerizable, gel-free composition of the invention. A wide variety of curing cycles, i.e., time-temperature sequences, can be applied during the polymerization of the substantially liquid, polymerizable gel-free composition. Normally, the curing cycle employed is based on the consideration of several factors including the size of the molding, the identity of the initiator and the reactivity of the ethylenically unsaturated material. A preferred curing cycle for use with a diisopropyl peroxydicarbonate initiator is shown in Table 1. This curing cycle is illustrative only, and others may be used including those described in Tables 1-4 of US Pat. 4959429. Tables 1-4 of US Patent 4959429 are incorporated herein by reference.

Table 1 Cumulative hours = Kiln temperature, ° C 0 44 10,1 58 12,0 64 14,5 70 15,2 77 16,2 85 16,5 90 17,0 104 17,25 104 19,75 80 (end of cycle) Note: The temperature changes between adjacent points shown in the table are linear.

When molds are used, the polymerizations are separated from the molds. The substantially gel-free, liquid, polymerizable composition can be polymerized to the thermoset state by exposure to ionizing radiation such as gamma radiation, X-rays, accelerated electrons, accelerated protons, accelerated alpha particles or high-speed neutrons. In the following, the invention will be described in greater detail with the following example which should be considered as illustrative rather than limiting, and in which all parts are by weight and all percentages are percentages by weight unless otherwise specified. . The values of the different physical properties were determined as follows: The densities of the substantially gel-free, liquid, polymerizable compositions were determined according to ASTM method D 4052-96. The refractive indices of the substantially liquid polymerizable gel-free compositions were determined according to ASTM method D 1218-92. The yellowness indexes of the substantially gel-free, liquid, polymerizable compositions were determined according to ASTM method E 450-82 (reapproved in 1987). The densities of solid polymerizations were determined according to ASTM test method D 792-91. The light transmissions of the solid polymerizations were determined on samples having a thickness of 3.2 millimeters according to ASTM test method D 1003-95 using a HunterLab® Colorquest® II sphere colorimeter system (Hunter Associates laboratory, Inc. Reston, Virginia, USA). As the light transmission approaches one hundred percent, the difference in light transmission for two samples of the same material, but with different thickness approaches zero. Consequently, light transmission values of 90 percent or higher determined with samples that have a thickness of up to 2 millimeters below or up to 4 millimeters above approximate reasonably well the luminous transmission with the standard thickness; The yellowness rates of the solid polymerizations on specimens having a thickness of 3.2 millimeters were determined according to ASTM test method D 1925-70 (reappropriated in 1988) using a HunterLab® Colorquest® sphere colorimeter system. II (Hunter Associates laboratory, Inc., Reston, Virginia, USA). Although the yellowness index seems to vary more with the sample thickness than the light transmission, the yellowness indices determined from samples having a thickness of up to 2 millimeters below or up to 4 millimeters above provide a useful general indication of the index of Yellowing with the standard thickness.

The thermal distortion temperatures of the solid polymerizations were determined for a deflection of 0.25 millimeters (10 mils) according to ASTM D 648-95. The Barcol hardness of the solid polymerisates was determined according to ASTM test method D 2583-95 using a Barcol printer and taking scaled readings 15 seconds after the tip of the printer penetrated the specimen. The refractive indices of the solid polymerisates were determined according to ASTM test method D 542-95; and the optical constringency of solid polymerisates was determined according to the usual definition: A = (n0 - 1) / (NF - n where: n0 is the refractive index with the use of a wavelength of 589.3 nanometers (ie, the mean of the yellow sodium duplex) nF is the index of refraction with the use of a wavelength of 486.1 nanometers (ie the blue line of hydrogen) and nc is the refractive index with the use of a wavelength of 656.3 nanometers (ie the line hydrogen red).

Example Diethylene glycol bischloroformate (DECF) was mixed [CAS 106-75-2], allylic alcohol (AA) [CAS 107-18-6] and diethylene glycol [DEG] [CAS 111-46-6] in the following molar ratio: 1,00 DECF / 1,96 AA / 0,21 DEG. 2.44 moles of NaOH (in the form of a 50% by weight solution in water) was slowly added to this mixture, while maintaining a reaction temperature of 5 ° C with external cooling.

After substantially all the chloroformate groups were reacted, the aqueous phase was separated and the resulting mixture of diethylene glycol compounds (allyl carbonate) was washed twice with water. It was vacuum stripped at an absolute pressure of about 1.3 pascals at a temperature of about 150 ° C. Table 2 shows the results of the high performance liquid chromatography analysis of the mixture of formula (10) and formula (11).

Table 2 Compound Quantity,% < .le area s r. 1 64.1 2 5.0 3 17.6 4 3.0 5 5.2 6 1.0 7 1.1 1 0.5 2 1.1 3 0.7 Total1 99.3 1 Other diverse ones were also present peaks of reduced areas of compounds of undetermined structures.

A thermoset, 114-liter glass-lined reactor equipped with a stirrer, and steam and city water sources connected to the sleeve for heating and cooling, respectively, 81.65 kilograms (kg) of the mixture were introduced into a reactor with a 114 liter glass-lined reactor. above of diethylene glycol compounds (allyl carbonate) characterized according to Table 2, 4.90 kg of 2,4,6-tris (allyloxy) -1,3,5-triazine containing approximately 180 ppm 4-methoxyphenol and 17, 3 grams of OO-tert-butyl-O- (2-ethylhexyl) monoperoxycarbonate. The charged materials were mixed to form a reaction mixture. The viscosity of the reaction mixture ranged between 30 and 31 cps at 25 ° C and the density was 1.1628 g / cm3 at 25 ° C. The reaction mixture was stirred and heated to 110 ° C and maintained at 110 ° C while being sprayed with nitrogen at a flow rate of 0.05 reactor volume / minute. Samples were removed every 30 minutes in order to monitor the viscosity of the reaction mixture. After 3.5 hours at 110 ° C, the viscosity at 25 ° C of the reaction mixture reached 90 cpm. Then, the sample frequency was increased once every 10 to 15 minutes. After 4 hours at 110 ° C, the viscosity at 25 ° C of the reaction mixture was 105 cps. Next, the reaction mixture was cooled to 80 ° C over the course of 30 minutes by gradually increasing the amount of cold water in the steam-water mixture that was being supplied at the inlet of the sleeve. Next, the reaction mixture was cooled to 50 ° C for a period of 1 hour. During cooling from 110 ° C, there was an additional increase in viscosity of 12 cps, resulting in a viscosity of 117 cps measured at 25 ° C for the product. The density of the product was 1.1780 g / cm3 at 25 ° C. According to the measurements carried out by iodometric titration, 9 percent of the double bonds were consumed during the reaction. The product was a composition substantially free of gel, liquid, polymerizable. Portions of the substantially gel-free, liquid, polymerizable composition above were stored for various periods of time after which several of the properties were determined. Table 3 shows the results: Table 3 Storage conditions Storage period, months 0 7 3 4 6 Storage temperature, ° C NA1 22-26 40-43 4 0-43 4 0-43 Properties Density at 25 ° C , g / cm3 1.1780 1.1780 1, 1781 1, 1789 1, 1798 Viscosity, at 25 ° C, cps 117 117 123 1 38 1 62 refractive index, np29 1.4627 1.4627 N D2 ND 1, 4627 yellowness index (50 mm path length) 1.7 1.7 1.9 1.7 2, 1 XNA = Not applicable 2ND = not determined Initiator was introduced into a portion of the composition substantially free of gel, liquid, polymerizable, without aging earlier with 3, 5 parts of diisopropyl peroxydicarbonate per 100 parts of composition substantially free of gel, polymerizable liquid, by weight (parts per 100 parts of resin (phr)). The initiator composition was poured into a mold and polymerized into a 3.175 millimeter thick sheet using a curing cycle from Table 1. The resulting thermosetting polymer was allowed to cool to room temperature and then subjected to testing to determine the various physical properties. A portion of the substantially liquid, polymerizable gel-free composition that had been aged for 6 months at 40 ° C-43 ° C with 3.5 phr of diisopropyl peroxydicarbonate was initiated. The initiator composition was poured into a mold and polymerized into a sheet of 3.175 millimeters thick using the curing cycle of Table 1. The resulting thermosetting polymer was allowed to cool to room temperature and was assayed to determine the various physical properties. Table 4 shows the results of the test.

Table 4 Prepolymer The initial prepolymer aging Shrinkage,% 10, 9 ND1 Density at 25 ° C, g / cmi33 i1 ,,: 3 32222 1, 321 Light transmission,,% 93, 9 93.7 yellowing index 0, 8 0.9 Thermal distortion temperature, ° C 55 57 Barcol hardness 23 28 refractive index, nD2C 1,5011 1,5013 Optical constringency 54 59 1ND = Not determined The present invention is claimed in the appended claims.

Claims (17)

1. RETVTNDICACIONKS: 1. A process for forming a prepolymer composition with poly (allyl carbonate) function, lacking gel, liquid, polymerizable consisting of: (a) heating a net composition including at least one monomer with poly (allyl) function carbonate) and a free radical initiator having a half-life of ten hours of at least 85 degrees Celsius at a temperature comprised between 5 ° C below the half-life temperature of ten hours of the free radical initiator and 150 ° C, to form a reaction mixture having a higher viscosity at 25 ° C within the range of 25 to 10,000 mPa.s and a use of an ethylenic double bond of at least 3 percent; and (b) for a period of less than 90 minutes, cooling the reaction mixture to a temperature of at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator.
2. 2. The process of claim 1, wherein the net composition is heated to a temperature within the range of 5 degrees Celsius below the half-life temperature of 10 hours of the free radical initiator at 30 degrees Celsius above the ten-hour half-life of the free radical initiator.
3. 3. The process of claim 1, wherein the net composition is heated to temperatures within the ten-hour half-life temperature range of the free radical initiator at 10 degrees Celsius above the half-life temperature of ten hours of the initiator of free radicals.
4. 4. The process of claim 1 wherein the mixture of the net composition is sprayed with a non-reactive gas for at least the first 15 minutes of the period of time during which it is heated.
5. 5. The process of claim 1, wherein the net composition is sprayed with a non-reactive gas throughout the period of time during which it is heated.
6. 6. The process of claim 1, wherein the reaction mixture has a viscosity at 25 ° C in the range of 45 to 3000 centipoise when cooling begins at a temperature at least 20 degrees Celsius below the average life temperature of ten hours of the initiator.
7. 7. The process of claim 1 wherein the reaction mixture has a viscosity at 25 ° C in the range between 80 and 120 centipoise when cooling begins at a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator.
8. 8. The process of claim 1, wherein the reaction mixture has a viscosity at 25 ° C in the range of 200 to 350 centipoise when cooling begins at a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator.
9. 9. The process of claim 1, wherein the reaction mixture has a double ethylenic bond utilization in the range of 3 to 16 percent when cooling begins at a temperature at least 20 degrees Celsius below the average life temperature ten hours from the initiator.
10. 10. The process of claim 1 wherein the reaction mixture has a double ethylenic bond utilization in the range of 8 to 12 percent when cooling begins at a temperature at least 20 degrees Celsius below the average life temperature of ten hours of the initiator.
11. 11. The process of claim 1 wherein the reaction mixture is cooled for a period of less than 1 hour at a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator.
12. 12. The process of claim 1, wherein the reaction mixture is cooled for a period of less than 30 minutes at a temperature at least 20 degrees Celsius below the half-life temperature of ten hours of the initiator.
13. 13. The process of claim 1 wherein the net composition includes bis (allyl carbonate) monomer of diethylene glycol including a mixture of diethylene glycol (allyl carbonate) compounds, each represented by one of these formulas: or by the formula: where s is a positive integer and t is a positive integer.
14. 14. The process of claim 13, wherein the diethylene glycol compound (allyl carbonate) for which the value of s is 1 constitutes from 25 to 99 percent of the area of the mixture of compounds (allyl carbonate) of diethylene glycol.
15. 15. The process of claim 13, wherein the diethylene glycol compound (allyl carbonate) for which the value of s is 1 constitutes from 25 to 95 percent of the area of the mixture of compounds (allyl carbonate) of diethylene glycol.
16. 16. The process of claim 13, wherein the diethylene glycol compound (allyl carbonate) for which the value of s is 1 constitutes from 82 to 95 percent of the area of the mixture of compounds (allyl carbonate) of diethylene glycol.
17. 17. The process of claim 13, wherein the diethylene glycol compound (allyl carbonate) for which the value of s is 1 constitutes from 25 to 75 percent of the area of the mixture of compounds (allyl carbonate) of diethylene glycol.