MXPA00011973A - Photopolymerizable dental compositions - Google Patents

Abstract

Photopolymerizable compositions that include free radically active and cationically active functional groups, and methods for polymerizing such compositions, in which the onset of cationic polymerization is controllably delayed to extend the time between formation of a moldable gel and formation of a hardened solid.

Description

FOTOPOLIMERI ZABLES DENTAL COMPOSITIONS FIELD OF THE INVENTION The present invention relates to polymer compositions having cationically active functional groups by free radicals.

BACKGROUND OF THE INVENTION The compositions based on acrylate and methacrylate are polymerized through a free-radical, single-stage mechanism. "Hybrid" compositions that exhibit components that can be polymerized both cationically and free radicals, have been proposed as such. Epoxy resins are typically used as the cationically polymerizable component, and offer the advantage of reduced shrinkage, relative to the acrylate and methacrylate based compositions. The hybrid composition is initially polymerized to form a moldable "gel" which can be shaped and REF. : 125409 can compact. As the polymerization proceeds, the gel forms a hard solid.

BRIEF DESCRIPTION OF THE INVENTION The inventors have discovered that a problem that occurs in hybrid compositions is the difficulty in controlling the time between gel formation and hardened solid formation. To solve that problem, the inventors have discovered polymerizable hybrid compositions, and methods for polymerizing the functional groups by free radicals and cationically active, of those compositions, in which the beginning of the cationic composition can be delayed in a controlled manner to prolong the time between the formation of the moldable gel and the formation of the hardened solid. The net result is improved processing flexibility. Accordingly, in a first aspect, the invention features a polymerizable composition that includes: (a) a cationically active functional group, (b) a functional group, active by free radicals, (c) a system of initiation. Examples of preferred or preferred polymerizable compositions are dental compositions such as dental adhesives, dental composite materials (including restorative and dental prostheses), and dental sealants.The photoinitiation system is capable of initiating, at a reaction temperature of about 40 ° C, the free radical polymerization of the free radical active functional group, after a period of finite induction Ti and the cationic polymerization of the cationically active functional group, after a period of finite induction T3 where T3 is greater than Ti, Tx T3 are measured in relation to the administration of the first dose of actinic radiation that occurs at 0. The photoinitiation system includes: (i) a source of species capable of initiating polymerization by free radicals, of the functional groups active by free radicals, and the cationic polymerization of the functional group cationically to and (ii) a cationic polymerization modifier. The amount and type of the modifier are selected such that in the absence of the modifier, the cationic polymerization of the cationically active functional group is initiated under the same irradiation conditions at the end of the finite induction period T2 (also measured in relation to To) where T2 is less than T3. As used herein, a "cationically active functional group" refers to a chemical moiety that is activated in the presence of an initiator capable of initiating cationic polymerization, such that it is available for reaction with other compounds containing ionically active ca functional groups. A "free radical active functional group" refers to a chemical moiety that is activated in the presence of an initiator capable of initiating free radical polymerization, such that it is available for reaction with other compounds having active functional groups by free radicals. "Polymerization initiation" after a "finite induction period" means that after a finite period of time has elapsed, an exotherm occurs (as measured by Differential Scanning Calorimetry), reflecting the initiation of the polymerizable groups. the initiation (and thus a successful polymerization of cationically polymerizable groups, to occur, it is said, if the area under the resulting exotherm peak is greater than 5% of the corresponding peak area for a control composition lacking the modifier , but irradiated under the same conditions presented in the examples, infra.The term "composite material" refers to a filled dental material.The term "restorative" refers to a composite material that is polymerized after it is placed on a site. adjacent to a tooth The term "prosthesis" refers to a composite material that is shaped and polymerized for its final use (eg, a crown, a bridge, a sheet, an inlay, or the like) before it be placed adjacent to a tooth.The term "sealant" refers to a slightly filled composite material or an unfilled dental material, which polymerizes after being cured. placed in a position adjacent to a tooth. Each of these materials is suitable for temporary or permanent use. Suitable components of the photopolymerizable composition include epoxy resins, which contain cationically active epoxy groups), vinyl ether resins (containing cationically active vinyl ether groups) and ethylenically active unsaturated compounds (containing free radical active unsaturated groups) examples of compounds ethylenically unsaturated, useful, include esters of acrylic acid, esters of methacrylic acid, esters of acrylic acid, with hydroxy functionality, esters of methacrylic acid with hydroxy functionality, and combinations thereof. Also convenient are the polymerizable components that contain both a cationically active functional group and a free radical functional group, in a single molecule. Examples include esters of acrylic acid with epoxy functionality, esters of methacrylic acid and combinations thereof.

A preferred material for component (i) of the photoinitiation system is an onium salt, for example, an iodonium salt. The photoinitiation system preferably contains a photosensitizer as such, for example, a visible light sensitizer. The term "visible light" refers to light having a wavelength of about 400 to about 1000 nanometers. Examples of suitable photosensitizers include the alpha diketones. The cationic polymerization modifier is selected in such a way that the photoinitiating system has a photoinduced potential lower than that of 3-dimethylaminoben zoi co acid in a standard solution of 2.9 x 10"5 moles / g of hexaf luoroantimoniat or of diphenyliodonium and 1.5 x 10 ~ 5 moles / g of camphorquinone in 2-butanone The modifiers are typically bases having pb values, measured in an aqueous solution, not greater than 10. Particularly preferred are modifiers in which the type and amount of the modifiers they select in such a way that the cationic polymerization of the cationically active functional group after a period of finite induction T3 proceeds with a speed greater than the speed occurring in the absence of the cationic polymerization modifier, under the same irradiation conditions. of suitable cationic polymerization modifiers, include aromatic sheets, (for example t-butyldim et ilani lina); aliphatic amines (for example, t r ime t i 1 - 1, 3 -pr opandi amine, 2- (methylamino) ethanol, and combinations thereof; aliphatic amides; aliphatic ureas; phosphines (for example aliphatic and aromatic); salts of organic or inorganic acids (for example salts of sulfinic acid); and combinations thereof. In a second aspect, the invention features a polymerization method of a photopolymerizable composition, which includes exposing the composition to a source of actinic radiation (preferably visible radiation) at a reaction temperature high enough to initiate the polymerization reaction. Preferably the reaction temperature is less than 40 ° C. The photopolymerizable compositions include the compositions described above. Also suitable are photopolymerizable compositions which include a cationically active functional group, a functional group by free radicals, and the photoinitiation system (as defined above), but which are not necessarily capable of polymerizing at temperatures less than 40 ° C. ° C. The method is particularly useful for impervious polymer compositions which are in the form of dental adhesives, dental composite materials, dental sealants and combinations thereof, in which case the method includes applying the photopolymerizable composition to a surface and carry out the polymerization inside the oral cavity at temperatures lower than 40 ° C. In one embodiment, the photopolymerizable composition is continuously exposed to actinic radiation starting at T0. In another embodiment, the photopolymerizable composition is exposed to a single dose of actinic radiation to To.

In one embodiment, the photopolymerizable composition is continuously exposed to actinic radiation starting at T0. In another embodiment, the photopolymerizable composition is exposed to a single dose of actinic radiation to To. In a third embodiment, three separate irradiation events occur. First, the photopolymerizable composition is exposed to a first reaction temperature, at a first dose of actinic radiation at Tc to initiate the polymerization of the active functional group by free radicals, after a period of finite induction Ti. Subsequently the polymerizable composition is exposed to a second reaction temperature, to a second dose of actinic radiation to initiate the polymerization of the cationically active functional group, after a finite induction period T3 which is greater than Ti (both Ti and T3 are measured in relation to To).

Preferably, actinic radiation of the same wavelength is used for both irradiation events. The first and second reaction temperatures are preferably substantially the same. In a third aspect the invention presents a method for preparing a polymerized dental composition in which the polymerizable composition includes two separate initiation systems. One of the initiation systems initiates the polymerization of the active functional group by free radicals at a first at a reaction temperature lower than 40 ° C. Suitable examples include photoinitiation systems, thermal initiation systems, and oxidation and reduction initiation systems (i.e. self-curing). The other initiation system is another photoinitiation system that initiates the photopolymerization of the cationically active functional group at a second reaction temperature of 40 ° C. The first and second reaction temperatures are preferably and substantially the same. The method includes applying the polymerizable composition to a surface, inducing polymerization of the active functional group free radical, and subsequently, in a separate step, exposing the composition to actinic radiation, to use polymerization of cationically active functional group. The polymerization is carried out inside the oral cavity. The invention provides polymerizable compositions hybrid in which the initiation of the polymerization of the functional groups cationically can be delayed with the start of the polymerization of the active functional group by free radicals, by a desired time without adversely affecting cationic polymerization one once it starts at the end of that period. The invention thus provides flexibility and control in applications for which the compositions are used. These advantages are particularly useful in dental applications where the compositions can be applied within the oral cavity. By retarding the polymerization of the component cationically, the dentist has ample time to apply and shape the composition so that it conforms to the contours of the oral surface to which they are applied, for example, a tooth. Once these operations have been completed, the dentist can then initiate the cationic polymerization to form the final hardened material. Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plot of the flow of heat versus time, obtained. by Photocalor Differential Sweeping Imaging for polymerizable compositions containing various concentrations of the cationic polymerization modifier, 2- (meth i lamino) -ethanol. Figure 2 is a graph of heat flow versus de'l time obtained by Fotocalorimet I RI Differential Scanning for polymerizable compositions containing various concentrations of the cationic polymerization modifier N, N, N '- 1 r t ime yl- 1, 3 -propandi amine.

DETAILED DESCRIPTION OF THE INVENTION Polymerizable composition The polymerizable compositions of the invention have one or more cationically active functional groups, one or more functional groups active by free radicals, and at least one initiation system. The compositions are designed for use in a step polymerization process in which the free radical functional groups are polymerized in a first step and the cationically active functional groups are subsequently polymerized in a second step. The initiation system can perform the dual function of initiating both cationic polymerization and free-radical polymerization. Alternatively, two separate initiation systems can be used, one of which initiates free radical polymerization and the other initiates cationic polymerization.

Simple Initiation System A suitable initiation system for initiating both free-radical polymerization and cationic polymerization is so designed that at a given reaction temperature, the initiation of free-radical polymerization occurs after a period of finite induction and the initiation of the cationic photonization occurs after a period of finite induction T3, where T3 is greater than Ti. Ti and T3 are measured in relation to the administration of the first dose of actinic radiation which begins at T0. The photoinitiation system includes: (i) a source of species capable of initiating free-radical polymerization of the functional group by free radicals, and cationic polymerization by cationically active functional group; and (ii) a cationic polymerization modifier. The amount and type of the modifier are selected such that in the presence of the modifier, the initiation of the cationic polymerization, under the same irradiation conditions, occurs at the end of a finite induction period T2 (also measured in relation to To), where T2 is less than T3. The induction periods (Ti, T2 and T3) can be measured using differential scanning calorimetry. Following the first irradiation event at T0, the exotherm of the reaction is measured as a function of time. Both the initiation of free radical polymerization and the initiation of cationic polymerization result in an exotherm, observed as a pair of separated peaks in a graph of heat flux versus time. The time in which initiation occurs is taken as the time at which the exotherm begins to grow. There are numerous examples of sources of species capable of initiating both. free radical polymerization such as cationic polymerization. Representative examples include the onium salts and cyclopentadienyl metal salts of arene from mixed ligands, with complex metal halide ions, as described in "CRC Handbook of Organic Photochemistry", vol II, ed. J.C.

Scaiano, pp. 335-339 (1989). Preferably the source is an onium salt, the iodonium salts (for example the iodonium salts of aryl) are particularly useful. The iodonium salt should be soluble in the composition and preferably is shelf stable, which means that it does not spontaneously promote polymerization when dissolved therein in the presence of a modifier and photosensitizer (if included) of cationic polymerization. Accordingly, the selection of a particular iodonium salt may depend to some degree on the particular polymerizable reagents, the cationic polymerization modifiers, and the sensitizers (if present). Suitable iodonium salts are described in U.S. Patent Nos. 3,729,313; 3,, 741, 769; 4,250,053; and 4,394,403, wherein the descriptions of the iodonium salt, thereof, are incorporated herein by reference. The iodonium salt can be a simple salt containing an anion such as Cl ", Br", I ", C H5S03", or C (S02CF3) 3", or a metal complex salt having an antimonate, arsenate, phosphate , or borate such as SbF5OH ", AsF6 ~, or B (C6F5) ~. If desired, mixtures of iodonium salts can be used. Examples of photoinitiators of useful aromatic iodonium complex salts include: diphenyliodonium tetrafluoroborate; di (4-methylphenyl) iodonium tetrafluoroborate; phenyl-4-methylphenyliodonium tetrafluoroborate; di (4-heptylphenyl) iodonium tetrafluoroborate; di (3-nitrophenyl-iodonium hexafluorophosphate, di (4-chlorophenyl) iodonium hexafluorophosphate; di (naphthyl) iodonium tetrafluoroborate; di (4-trifluoromethyl) -iodonium tetrafluoroborate; hexafluor-fos-fat or diphenyliodonium hexafluorophosphate of di (4-methylphenyl) iodonium; diphenyliodonium hexafluoroarsenate; di (4-phenoxyphenyl) iodonium tetrafluoroborate; phenyl-2-phenyliodonium hexafluorophosphate; 3,5-dimethylpyrazolyl-4-phenyliodonium hexafluorophosphate; diphenyliodonium hexafluoroantimonate; 2, 2 '-difenyliodonium tetrafluroborate; di (2,4-dichlorophenyl) iodonium hexafluorophosphate; di (4-bromophenyl) iodonium hexafluorophosphate; di (4-methoxy-enyl) yodonium hexafluorophosphate; di (3-carboxyphenyl) iodonium hexafluorophosphate; di (3-methoxycarbonyl) iodonium hexafluorophosphate; di (3-methoxy sulphonyl phenyl) iodonium hexafluorophosphate; di (4-acetamidophenyl) iodonium hexafluorophosphate; di (2-benzothienyl) iodonium hexafluorophosphate; diphenyliodonium hexafluoroantimonate; diphenyldifluoromethylsulfonylmethyl diphenyl or diaryliodonium; or diphenyl or diaryliodonium tetra (pentafluorophenyl) borate. The cationic polymerization modifier preferably has a photoinduced potential lower than that of 3-dimethylaminobenzoic acid in a standard solution of 2.9 × 10 ~ 5 mol / g of hexafluor oant imoniat or diphenyliodonium 1.5 × 10 'mole / g of camphorquinone in 2-butanone. The photo-induced potential can be evaluated in the following way. A standard solution containing 2.9 x 10"5 mol / g hexafluoroant imoniat or diphenyliodonium and 1.5 x 10" 5 mol / g canf orquinone in 2-butanone is prepared. Then a pH electrode is immersed in the solution and the pH meter is calibrated at zero mV. Subsequently, an analysis solution of the standard solution and the modifier is prepared, using the modifier at a concentration of 2.9 x 10 ~ 5 moles / g. This analysis solution is irradiated using blue light having a wavelength of about 400 to 500 nm having an intensity of about 200 to 400 mW / cm2 for a time of about 5 to 10 seconds at a distance of about 1 mm . The millivolts are then determined in relation to the standard solution by immersing the pH electrode in the analysis solution and obtaining a reading in mV in the pH meter The useful modifier are those compounds that provide a reading no greater than approximately 75. mV in relation to the standard solution In certain cases there may be some uncertainty concerning the result of the previous procedure, this may be due to questions of uncertainty arising from the instrumentation used, from the way in which the procedure was carried out. , or of other factors, or it may be desired to verify the convenience of a particular modifier A second analysis can be performed to verify the result obtained by following the above procedure and resolve any uncertainty The second method involves the evaluation of the photo-induced potential of a system of initiator that includes the modifier, compared to a system that i include 3-dimethyl t-amminobenzoic acid co. For this method, a standard solution of 2.9 x 10"5 moles / g of hexaf luoroant imoniat or of diphenyliodonium, 1.5 x 10" 5 moles / g of camphorquinone and 2.9 x 10"5 moles / g of acid 3-dime is prepared t ila inoben zo i co in 2-butanone Then a pH electrode is immersed in the solution and a pH meter is calibrated to zero V. The standard solution is irradiated with blue light having a wavelength of between approximately 400 and 500 nm and an intensity of 200 to 400 mW / cm2 for a time of approximately 5 to 10 seconds, using a concentrated light source, such as a light for dental curing, at a distance of approximately 1 mm. light, the potential of the solution is measured by immersing a pH electrode in the standard irradiated solution and reading the potential in mV using a PH meter, then preparing an analysis solution using 2.9 x 10"5 moles / g of diphenyliodonium hexafluoroant imonium, 1.5 x 10 ~ 5 moles / g of canfin orquinone, and 2.9 x 10"5 moles / g of the modifier, in 2-butanone. The analysis solution is irradiated and the photoinduced potential is measured using the same technique described for the standard solution. If the analysis solution has a photoinduced potential that is lower than that of the 3-dimethylaminobenzoic acid containing the standard solution, then the modifier can be a useful cationic polymerization modifier. Useful cationic polymerization modifiers are typically bases having pKb values, measured in aqueous solution, less than 10. Examples of suitable classes of cationic polymerization modifiers include aromatic amines, aliphatic amines, aliphatic amides, aliphatic ureas; aliphatic and aromatic phosphines, and salts of organic and inorganic acids (for example, salts of sulfinic acid). Specific examples include 4- (dimethylamino) phenylacetic acid, dimethylaminophene anol, dihydroxy p-toluidine, N- (3, 5-dimethyphenyl) -N, N-diethanolamine, 2,4,6-pent amet ilani 1 ina , tell me you lbencyl lamina, N, N-dimethylacetamine, t et ramet i lurea, N-methyldiethanolamine, triethylamine, 2- (methylamino) ethanol, dibutyl amine, diethanolamine, N-ethymorpholine, t rimet i 1 - 1, 3 -propanedi amine, 3-quinuclidinol, triphenylphosphine, sodium toluene, tri-cyclohexyl-1 -succin, N- and ilp-rol idona, and t -but i 1 tell me ti lani 1 ina. These modifiers can be used alone or in combination with each other, or with a material that has a photo-induced material greater than that of 3-dimethylaminobenzoic acid in a standard solution of 2.9 x 10-5 moles / g of hexafluor oant imoniat or diphenyliodonium and 1.5 x 10"5 moles7 g of canfin orquinone in 2-butanone, an example of that material is ethyl 4- (dimethylamino) benzoate (" EDMAB ") .The choice of modifier, and the amount thereof it is selected on the basis of the light-curing position and the degree to which it is desired to retard the initiation of the cationically polymerizable groups (ie, what the target value of T3 is.) Furthermore, it is important that the amount of the modifier is not so high as for the polymerization to be completely inhibited.As discussed in the brief description of the invention, above, a successful cationic polymerization is one in which the area under the peak of the exotherm that accompanies the cationic initiation to the to be determined by differential scanning calorimetry, is greater than 5% of the corresponding peak area for a control composition lacking the modifier, but irradiated under the same conditions presented in the examples, infra. Another variable that influences the fact that if a successful polymerization occurs or not, is the reaction temperature. For example, some compositions that do not polymerize successfully (as defined above) at a reaction temperature, can polymerize successfully at a higher temperature. However, it is generally preferred that the polymerization reaction will be able to be carried out at temperatures lower than 40 ° C. This feature is particularly useful in the case of dental compositions wherein the polymerization takes place within the oral cavity, where the temperature is body temperature (37 ° C) or slightly higher. If the composition is capable of polymerizing at reaction temperatures of less than 40 ° C, the polymerization reaction can be carried out without supplying additional heat. The inventors have discovered that a class of cationic polymerization modifiers offers an additional advantage. Specifically, these modifiers not only delay the initiation of cationic polymerization but, at the start, increase the polymerization rate in relation to the polymerization rate in the absence of the cationic polymerization modifier, carried out under the same irradiation conditions. The speed is measured using Differential Scanning Calorimetry, as the difference between the time required to reach the height of the maximum exotherm peak (T) and the time at which the polymerization is initiated (ie, the induction time). Examples of modifiers, which have been found to exhibit such behavior, include the aliphatic amines, such as N-methyldiethanolamine, triethylamine, dibutylcholine, diethanolamine, Ne-lignolphin, 2- (methylamino) ethanol, and tell me you lbenci lamina. The initiation system may also include a sensitizer such as a visible light sensitizer that is soluble in the polymerizable composition. The sensitizer is preferably capable of absorbing light having wavelengths in the range from about 300 to about 1000 nanometers Examples of suitable sensitizers include ketones, coumarin dyes (e.g., ce tcumerizes), dyes of xanthene, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons, amino-t-ioletone p-subsides, aminotriaryl methanes, mercyanins , escuarilium dyes and pyridinium dyes.Ketones (for example monoketones or alpha-say tones), cet ocumar inas, aminars i 1 ketones, and thyroloketone p-subs tute amino compounds, are the preferred sensitizers. For applications that require deep curing (eg, curing of highly filled composites), it is preferred to employ sensitizers having an extinction coefficient below about 1000 lmol_1cm -1, more preferably about below 100 lmol ~ 1cm ~ 1, at the desired wavelength of the irradiation for the photopolymerization. Al-di-ketones are examples of a class of sensitizers having this property and are particularly preferred for dental applications. Examples of visible light sensitizers, particularly preferred include canf orquinone, glyoxal; the biacetyl; 3,3,6,6-tetramethylcyclohexanedione; 3, 3, 7, 7-tetramethyl-1,2-cycloheptanedione; 3, 3, 8, 8-tetramethyl-l, 2-cyclooctanedione; 3, 3, 18, 18-tetramethyl-l, 2-cyclooctadecandione; dipivaloyl; benzyl; Furyl hydroxybenzyl; 2,3-butanedione; 2,3-pentandione; 2,3-hexanedione; 3,4-hexanedione; 2,3-heptanedione; 3,4-heptanedione; 2, 3 -oct andiona; 4, 5-oct andiona; and 1,2-cyclohexanedione. Of these, canfin orquinone is the most preferred sensitizer.

Double Initiation Systems Stepwise polymerizations can also be carried out, using an initiation system for free radical polymerization and a separate initiation system for cationic polymerization. The initiation system for free radical polymerization is selected such that upon activation, only free radical polymerization is initiated. A class of initiators capable of initiating the polymerization of functional groups active by free radicals, but which are not cationically active functional groups includes conventional chemical initiator systems such as a combination of a peroxide and an amine. These initiators, which are based on a thermal reduction and oxidation reaction, are often referred to as "self-curing catalysts". These are typically supplied as two-part systems in which reagents are stored separately and then combined immediately before use. A second class of initiators, capable of initiating the polymerization of functional groups active by free radicals, but not cationically active functional groups, includes photoinitiators that generate free radicals, optionally combined with a photosensitizer or accelerator. These initiators are typically capable of general free radicals for addition polymerization at a certain wavelength between 200 and 800 nm. Examples include the alpha-diketones, the monoacetes, the alpha-diketones or the cet aldehydes, acyloins and their corresponding ethers, the haloesters substituted with chromophore and the substituted halomethyl-oxadiazoles with chromophore. A third class capable of initiating the polymerization of active functional groups by free radicals, but not of cationically active functional groups, includes thermal initiators that generate free radicals. Examples include peroxides and azo compounds such as AIBN. The double initiation systems further include a separate photoinitiation system to initiate the polymerization of cationically active functional groups. The cationic initiation system is selected such that activation of the free radical initiation system does not activate the cationic initiation system. Examples of cationic initiation photo systems for a dual initiation system composition include onium salts and mixed cyclopentadienyl metal salts of mixed ligand, with complex metal halide ions, described above.

Polymerizable Components The polymerizable compositions include cationically active functional groups and functional groups active by free radicals. Materials that have cationically active functional groups include epoxy resins that can be cationically polymerized. These materials are organic compounds that have an oxirane ring, that is, a group of the formula , _c. OR which can be polymerized by ring opening. These materials include monomeric epoxide compounds and epoxies of the polymeric type and can be aliphatic, cycloaliphatic, aromatic or heterocyclic. These materials generally have, on average, at least 1 polymerizable epoxy group per molecule, preferably at least about 1.5 and more preferably at least 2 polymerizable epoxy groups per molecule. Polymeric epoxides include linear polymers having terminal epoxide groups (eg, a diglycidyl ether of a polyoxyalkylene glycol), polymers having oxirane units in the main chain (eg, polybutadiene polyepoxide) and polymers having pendant epoxies ( for example, a polymer or copolymer of glycidyl methacrylate). Epoxides can be pure compounds or they can be mixtures of compounds containing 1, 2 or more epoxy groups per molecule. The "average" number of epoxy groups per molecule is determined by dividing the total number of epoxy groups in the material containing the epoxy, between the total number of molecules that contain the epoxy, present. These epoxy-containing materials can vary from low molecular weight monomeric materials to high molecular weight polymers and the nature of their main chain and substituent groups can vary greatly. Illustrative of permissible substituent groups include halogens, ester groups, ethers, sulfonate groups, siloxane groups, nitro groups, phosphate groups and the like. The molecular weight of the epoxy-containing materials can vary from about 58 to about 100,000 or more. Useful epoxy-containing materials include those containing cyclohexane oxide groups, such as the epoxy cyclohexane carboxylates, typified by 3,4-hepoxycyclohexylmethyl-3, 4-epoxycyclohexne carboxylate, 3,4-epoxy carboxylate -2-met i 1 ci clohexi lme ti 1 -3,4-epoxy-2-methylcyclohexane, and bis (3, -epoxy-6-met ilcyclohexylmethyl) adipate. For a more detailed list of epoxies of this nature, useful, reference is made to U.S. Patent No. 3,117,099, which is incorporated herein by reference. Additional epoxy-containing materials, which are useful in the compositions of this invention, include the glycidyl ether monomers of the formula Examples are the glycidyl ethers of polyhydric phenols obtained by reacting a polyhydric phenol with an excess of chlorohydrin such as epichlorohydrin (for example, the ether of polyhydric phenols). glycidyl of 2, 2, -bi s - (2,3-epoxypropoxy f ene 1) -propane). Additional examples of epoxides of this type are described in U.S. Patent No. 3,018,262, which is incorporated herein by reference, and in "Manual of Epoxy Resins" by Lee and Neville, McGraw-Hill Book Co., New York ( 1967). There is a major list of commercially available epoxy resins, which can be used in this invention. in particular, epoxies that are readily available include the oxide of acetylene oxide, epichlorohydrin, styrene oxide, vinylcyclohexene oxide, glycidol, glycidyl methacrylate, diglycidyl ether of Bisphenol A (for example, those available under the trade designations). Epon 828"," Epon 825"," Epon 1004"and" Epon 1010"from .Shell Chemical Co.," DER-331"," DER-332", and" DER-334", from Dow Chemical Co.) , vinylcyclohexane dioxide (for example "ERL-4206" by Union Carbide Corp.), 3,4-epoxycyclohexylmethyl-3,4-epoxy-cyclohexane carboxylate (for example "ERL-4221" or "CYRACURE UVR 6110" or "UVR 6105"by Union Carbide Corp.), 3, 4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methyl-cyclohexene carboxylate (e.g.," ERL-4201"from Union Carbide Corp.), bi s (3, 4-epoxy-6-methylcyclohexylmethyl) adipate (for example "ERL 4289" from Union Carbide Corp.), bis (2,3-epoxycyclopentyl) ether (for example "ERL -0400" from Union Carbide Corp.), modified aliphatic epoxy of polypropylene glycol (e.g. "ERL-4050" and "ERL-4052" of Union Carbide Corp.), dipentene dioxide (e.g. "ERL-4269" from Union Carbide Corp.), epoxidized polybutadiene (e.g. " Oxiron 2001"by FMC Corp.), silicone resins containing epoxy functionality, epoxies" flame retardant "(for example," DER-580"an epoxy resin of the brominated bisphenol type, available from Dow Chemical Co.), ether diglycidyl 1,4-butyl phenol formaldehyde novolak (for example "DEN-431" DEN-438 from Dow Chemical Co.) resorcinium diglycidyl ether (eg, "Kopoxite" from Koppers Company, Inc.), bis (3,4-epoxycyclohexyl) adipate (e.g. "ERL-4299" or "UVR -6128", by Union Carbide Corp.), 2- (3, 4-epoxycyclohexyl-5, 5-spiro-3, 4-epoxy) cyclohexane-meta-dioxane (e.g.," ERL-4234"from Union Carbide Corp .), 1,2-epoxyhexadecane vinylcyclohexene monoxide (for example "UVR-6216" from Union Carbide Corp.), glycidyl alkyl ethers such as the alkyl glycidyl ether of 8 to 10 carbon atoms (eg, "HELOXY Modifier 7"from Shell Chemical Co.), alkyl glycidyl ether of 12 to 14 carbon atoms (eg," HELOXY Modifier 8"from Shell Chemical Co.), butyl glycidyl ether (eg," HELOXY Modifier 61"from Shell Chemical Co.), cresyl glycidyl ether (eg" HELOXY Modifier 62"from Shell Chemical Co.), p-tert-butyl phenyl glycidyl ether (eg," HELOXY Modifier 65"from Shell Chemic al.), polyfunctional glycidyl ether such as diglycidyl ether of 1,4-butylamino (for example, "HELOXY Modifier 67" from Shell Chemical Co. ), diglycidyl ether of neopent i 1 gl i col (for example, "HELOXY Modifier 68" from Shell Chemical Co.), diglycidyl ether of cyclohexanedimethanol (for example, "HELOXY Modifier 107" from Shell Chemical Co.), triglycidyl ether of t rime t ilolet anus (for example, "HELOXY Modifier 44" from Shell Chemical Co.), trimethylolpropane triglycidyl ether (for example, "HELOXY Modifier 48" from Shell Chemical Co.), polyethylene glycol ether an aliphatic polyol (eg, "HELOXY Modifier 84" from Shell Chemical Co.), polyglycol diepoxide (eg, "HELOXY Modifier 32" from Shell Chemical Co.), bisphenol F epoxides (e.g., "EPN-1138" or "GY-281" from Ciba Geigy Corp.), 9,9-bis [4- (2,3-epoxypropoxy) -phenyl-fluorenone (e.g., "Epon 1079" from Shell Chemical Co.) . Still other epoxy resins contain copolymers of esters of acrylic acid or glycidol such as glycidyl acrylate and glycidyl methacrylate with one or more copolymerizable vinyl compounds. Examples of these copolymers are glyceryl methacrylate -methacrylate in proportions of 1: 1, methyloacrylate methacrylate or glycidyl methacrylate in 1: 1 proportions, and methyl methacrylate-ethylacrylate -methyl acrylate. i the glycidyl to, in proportions of 62.5: 24: 13.5. Other useful epoxy resins are well known and contain epoxides such as epichlor or hydroxides, alkylene oxides, for example propylene oxide, styrene oxide.; alkenyl oxides, for example butadiene oxide; glycidyl esters, for example ethyl glycidate. Mixtures of various materials containing epoxies are also contemplated. Examples of such mixtures include two or more weight average molecular weight distributions of epoxy-containing compounds, such as those of low molecular weight (below 200), of intermediate molecular weight. (from about 200 to 10,000) and of higher molecular weight (above about 10,000). Alternatively or additionally, the epoxy resin may contain a mixture of epoxy-containing materials, having different chemical natures, such as aliphatics and aromatics or functionalities such as polar and non-polar. Other types of useful materials having cationically active functional groups include vinyl ethers, oxetanes, spiro-orthocarbonates, spi ro-ort or es, and the like. The materials having functional groups by free radicals include monomers, oligomers and polymers having one or more ethylenically unsaturated groups. Suitable materials contain at least one ethylenically unsaturated bond, and are capable of undergoing addition polymerization. Those materials that can be polymerized by free radicals include monoacrylates, diacrylates or polyacrylates and methacrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, isopropyl methacrylate, n-hexyl acrylate, stearyl acrylate, acrylate. of allyl, glycerol diacrylate, glyceryl triacrylate, ethylene glycol diacrylate, diacrylate of diet ilenegl i col, dimethacrylate. of triethylene glycol, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, trimethylolpropane triacrylate, 1,2,4-butanetriol tri-acrylate, 1,4-cyclohexanediol diacrylate, pentaerythritol triachloride, tetraacrylate of pentaerythritol, tet rametacr urate of pentaerythritol, sorbitol hexacrylate, bis [l- (2-acryloxy)] - p-ethoxyphenyl dimethyl methane, bis [1 - (3-acyloxy-2-hydroxy)] - p-propoxy fe .nildimet ilmet anus, and trimether acrylate isocyanurate of trishidr oxyethyl; the bis-acrylics and bi-methyl acrylates of polyethylene glycols of molecular weight from 200 to 500, copolymerizable mixtures of acrylated monomers such as those of U.S. Patent No. 4,652,274, and acrylated oligomers such as those of U.S. Patent No. 4,642,126; and vinyl compounds such as styrene, diallyl phthalate, divinyl succinate, divinyl adipate and divinyl phthalate. If desired, mixtures of two or more of these materials that can be polymerized by free radicals can be used. If desired, functional groups, cationically active and active by free radicals, can be found in a single molecule. These molecules can be obtained, for example, by reacting a di-epoxide or poly-epoxide with one or more equivalents of an ethylenically unsaturated carboxylic acid. An example of that material is the reaction product of UVR-6105 (available in Union Carbide) with an equivalent of methacrylic acid. The materials, commercially available, which have epoxy functionalities and active functionalities by free radicals, include the "Cyclomer" series, such as the Cyclomer M-100, M-101, or A-200 available from Daicel Chemical, Japan, and the Ebecryl -3605 available from Radcure Specialties.

Other additives The polymerizable composition may further include a hydroxyl-containing material. Suitable hydroxyl-containing materials can be any organic material having hydroxyl functionalis of at least 1 and preferably at least 2. Preferably, the hydroxyl-containing material contains two or more aliphatic, primary or secondary hydroxyl groups (ie, the hydroxyl group is directly linked to a non-aromatic carbon atom). The hydroxyl groups may be terminally located, or may be suspended from a polymer or copolymer. The molecular weight of the hydroxyl-containing organic material can vary from a very low molecular weight (for example of 32) to a very high molecular weight (for example of one million or more). Suitable hydroxyl-containing materials can have low molecular weights, i.e. from about 32 to 200, an intermediate molecular weight, i.e. from about 200 to 10,000, or a high molecular weight. That is, above about 10,000. As used herein, all molecular weights are weight average molecular weights. The hydroxyl-containing materials may be non-aromatic in nature or may contain aromatic functionality. The hydroxyl-containing material may optionally contain heteroatoms in the main chain of the molecule, such as nitrogen, oxygen, sulfur, and the like. The hydroxyl-containing material can be selected, for example, from natural cellulose materials or synthetically prepared. Of course, the hydroxyl-containing material is also substantially free of groups that can be thermally or photically unstable; that is, the material will not decompose or release volatile components at temperatures below about 100 ° C or in the presence of actinic light which may be found during the desired polymerization conditions, for the free radical active components, of the polymerizable composition . Representative examples of suitable hydroxyl-containing materials having a hydroxyl functionality of 1 include the alkanols, monoalkyl ethers of polyoxyalkylene glycols, monoalkyl ethers of alkylene glycols, and others known in the art. Representative examples of polyhydroxiorganic, monomeric materials include the alkylene glycols (eg, 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 2-ethyl-1, , 6-hexanediol, bis (hydroxymethyl) cyclohexane, 1,18-dihydroxioct-adecano, 3-chloro-1,2-propanediol); polyhydroxyalkanes (for example, glycerin, trimethyl ioletane, pentaerythritol, sorbitol) and other polyhydroxy compounds; 2-butyne-1,4-diol; 4,4-bis (hydroxymethyl) difnylsulfone; Castor oil; and similar.

Representative examples of polymeric hydroxyl-containing materials include polyoxyethylene glycols and polyoxypropylene glycols, and particularly polyoxyethylene and polyoxypropylene glycol diols and triols, having molecular weights from about 200 to about 10,000, corresponding to an equivalent hydroxy weight, from 100 to 5000 for diols or from 70 to 3300 for triols, polytetramethylene ether glycols, such as polytetrahydrofuran or "poly THF" of variable molecular weight; copolymers of hydroxypropyl and hydroxyethyl acrylates and methacrylates, with other monomers which can be polymerized by free radicals such as acrylate esters, vinyl halides, or styrene; copolymers containing pendant hydroxy groups formed by the hydrolysis or partial hydrolysis of the vinyl acetate copolymers, polyvinyl acetal resins containing pendant hydroxyl groups; modified cellulose polymers such as hydroxyethylated and hydropropylated cellulose; polyesters with hydroxy termination; polylactones with hydroxy termination and particularly the polycaprolactones; polyoxyethylene glycol or polyoxypropylene glycols; and the polyalkadienes with hydroxy termination. Commercially available, useful hydroxyl-containing materials include the "TERATHANE" series of polytetramethyl ether glycols such as "TERATHANE" 650,1000,2000 and 2900 (available from du Pont de Nemours, Wilmington, DE) the "PEP" series "of polyoxyalkylene tetroles having a secondary hydroxyl groups, such as the" PEP "450,550 and 650; the "BUTVAR" series of polyvinylacetal resins such as "BUTVAR" B-72A, B-73, B-76, B-90 and B-98 (available from Monsanto Chemical Company, St. Louis, MO); and the "FORMVAR" series of resins such as 7/70, 12/85, 7 / 95S, 7 / 95E, 15 / 95S and 15 / 95E (available from Monsanto Chemical Company). The "TONE" series of polycaprolactone polyols such as "TONE" 0200, 0210, 0230, 0240, 0300 and 0301 (available from Union Carbide); the aliphatic polyester diol "PARAPLEX U-148" (available from Rohm _ and Haas, Philadelphia, PA), the "MULTRON" R series of saturated polyester polyols such as "MULTRON" R-2, R-12A, R- 16, R-18, R-38, R-68 and R-74 (available from Mobay Chemical Co.); the cellulose hidopr opi 1 ada "KLUCEL E" has an equivalent weight of approximately 100 (available from Hercules Inc.); "Alcohol-Soluble Butyrate" cellulose acetate butyrate ester having a hydroxyl equivalent weight of about 400 (available from Eastman Kodak Co., Rochester, NY); polyether polyols such as propylene glycol diol (for example "ARCOL PPG-425", "Arcol PPG-725", "ARCOL PPG-1025", "ARCOL PPG-2025", ARCOL PPG-3025"," ARCOL PPG-4025"by ARCO Chemical Co.), the polypropylene glycol triol (for example," ARCOL LT-28"," ARCOL LHT-42"," ARCOL LHT-112"," ARCOL LHT-240"," ARCOL LG-56"," ARCOL LG-168"," ARCOL LG-650"by ARCO Chemical Co.); with polyoxypropylene triol or diol (for example "ARCOL 11-27", "ARCOL 11-34", "ARCOL E-351", "ARCOL E-452", "ARCOL E-785", "ARCOL E-786" , by ARCO Chemical Co.), ethoxylated bis-phenol A, polyols based on propylene oxide or ethylene oxide (for example the polyether polyols "VORANOL" from Dow Chemical Co.) .The amount of the organic material which contains hydroxyl used in the polymerizable compositions, can vary in wide ranges, depending on factors such as the compatibility of the hydroxyl-containing material, with the epoxide and / or component that can be polymerized by free radicals, the equivalent weight and the hydroxyl-containing functionality, the properties desired physical properties in the final composition, the desired polymerization rate, and the like. Mixtures of various hydroxyl-containing materials can also be used. Examples of such mixtures include two or more molecular weight distributions of hydroxyl-containing compounds, such as low molecular weight (below 200), intermediate molecular weight (from about 200 to 10,000) and higher molecular weight (above about 10,000 ). Alternatively or additionally, the hydroxyl-containing material may contain a mixture of hydroxyl-containing materials and having different chemical natures, such as aliphatic and aromatic, or functionalities such as polar and non-polar. As a further example, mixtures of two or more hydroxy, polyfunctional materials, or one or more monofunctional hydroxy materials can be used with polyfunctional hydroxy materials. The porable material (s) can also contain hydroxyl groups and functional groups active by free radicals, in a single molecule. Examples of such materials include hydroxyalkyl acrylates and hydroxyalkyl methacrylates, such as hydroxyethyl acrylate, hydroxyethyl methacrylate; glycerol mono (meth) acrylate or glycerol di (meth) acrylate; the mono (meth) acrylate of trimethylolpropane or the di- (me t) acrylate of trimethylolpropane, the mono- (me t) acrylate of pentaerythritol, the di-, (me t) acrylate of pentaerythritol and the tri- (meth) acrylate pentaerythritol, sorbitol mono (meth) acrylate, sorbitol di- (meth) acrylate, sorbitol tri- (meth) acrylate, sorbitol tetra- (meth) acrylate, or pent - (me t) acrylate sorbitol; and 2, 2-bis [4- (2 -hi dr oxy-3-met acryloxypropoxy) phenyl] propane. The polymerizable material (s) (en) may also contain hydroxyl groups and cationically active functional groups, in a single molecule. An example is a single molecule that includes both hydroxyl groups and epoxy groups. The polymerizable composition may also contain suitable additives such as fluoride sources, antimicrobial agents, accelerators, stabilizers, absorbers, pigments, dyes, modifiers. viscosity, surface tension and auxiliary humidifiers, antioxidants, fillers and other ingredients well known to those skilled in the art. The amounts and types of each ingredient should be adjusted to provide the desired physical and handling properties before and after polymerization.

Polymerization Procedure The polymerizable compositions are prepared by mixing, under conditions of "safe light", the different components of the compositions. Suitable inert solvents may be used, if desired when mixing is effected. Examples of suitable solvents include acetone, dichloromethane, and acetonitrile. In the case of individual initiation systems, the polymerization is carried out by exposing the composition to a radiation source, preferably to a source of visible light. It is convenient to use light sources that emit ultraviolet or visible light, such as quartz halogen lamps, tungsten halogen lamps, mercury arcs, carbon arcs, low, medium and high pressure mercury lamps, plasma arcs, light-emitting diodes and lightning bolts. To be. In general, useful light sources have intensities that are in the range of 200 to 500 m W / cm2. One example, which is particularly useful for dental applications, is a Visilux dental curing light commercially available from 3M Company of St. Paul, MN. These lights have an intensity of approximately 200 to 400 m W / cm2 at a wavelength of 400 to 500 nm. The exhibition can be done in several ways. For example, the polymerizable composition can be continuously exposed to radiation, throughout the polymerization process. It is also possible to expose the composition to a single dose of radiation, and then remove the source of radiation, thereby allowing the polymerization to occur. However, preferably the composition is initially exposed to a single radiation dose, to initiate the polymerization of the functional groups by free radicals, followed by exposure to a second radiation dose to initiate the polymerization of the cationically active functional groups. Where double exposures are used, the intensity of each dosage can be the same or different. Similarly, the total energy of each exposure can be the same or different. Regardless of the particular irradiation protocol used, the cationic polymerization initiating species are generated during the first exposure. However, the amount of the cationic polymerization modifier is sufficient to purify some or all of these species, thereby preventing the cationic polymerization from occurring until a desired time has elapsed. In the case of a single dose exposure, the amount of modifier is adjusted such that a sufficient number of cationic polymerization initiating species remains to initiate the cationic polymerization. However, the onset is delayed because the concentration of the initiating species of the cationic polymerization has been effectively reduced. In the case of exposure to continuous radiation, additional cationic polymerization initiator species continue to be generated, increasing the concentration of these species. However, again, due to the cationic debugging effect of the modifier, the concentration of those species is lower than what would have been in the absence of the modifier, resulting in a delayed cationic polymerization. In the case of the double exposure protocol, the concentration of the modifier is adjusted such that it substantially cleans all available cationic polymerization initiating species, thereby preventing any significant amount of cationic polymerization from occurring. However, with exposure to a second dose of radiation, additional species are generated. Because the modifier molecules are no longer available, to perform the purification function, these species then proceed to initiate the cationic polymerization. Therefore the net effect is to "turn off" the cationic polymerization until a certain desired time has elapsed and then "turn on" again at the end of this period.

The delay of the initiation of the cationic polymerization is also achieved using the double initiation systems. In these systems, the preferential polymerization of the active functional groups by free radicals is initiated, selectively activating the system of initiation by free radicals. Because this system does not generate cationically active species, cationic polymerization does not occur. After a desired time has elapsed, the cationic polymerization is activated by exposing the composition to radiation (preferably visible radiation), at which point the cationic polymerization proceeds. Regardless of whether single or double initiation systems are used, the ability to carry out step curing offers the advantage of controlling the overall polymerization process. This ability is particularly useful in dentistry, since the viscosity (and therefore the ease with which it is handled) of the composition changes significantly through the polymerization process. For example, the previously polymerized composition is generally in the form of a viscous liquid that can be easily applied to a tooth. With irradiation, the polymerization of the active groups by free radicals occurs, leading to the final formation of a "gel" of higher viscosity. This gel has unique handling characteristics. Specifically, it can be shaped, can be adapted, carved, or manipulated in another way, easily; In this way the dentist can manipulate it to fill in cracks and adjust it to the desired portions of the tooth surface. A. Once the handling is complete, the cationic polymerization is initiated, causing the composition to form a hardened solid that provides the final characteristics of the product. However, this solid can not be handled without using mechanical or machined abrasives (for example, milling cutters or bits). By controlling the onset of cationic polymerization, the dentist has ample time to manipulate the composition while still in the gel form.

The invention will now be described further, through the following examples.

EXAMPLES Examples 1-21 and Control A concentrated resin solution (Concentrated Solution # 1) was prepared by combining 5.0 grams of cartridqinone (CPQ) and 15.0 grams of diaryliodonium hexafluoroantimonate (CD1012 from Sartomer) with 720.0 grams of CyracureMT UVR 6105, diepoxy resin. cloal if á ti ca (available from Union Carbide), 180.0 grams of diol of po lit etrahydrofuran having an average molecular weight of 250 (p-THF-250, available from Aldrich Chemical Co.), and 100 grams of acrylate oligomer (Ebercryl 1830, available from UCB Raducure, Inc.)), and stirring until a homogeneous mixture is obtained, under safe light conditions. A second concentrated solution (Concentrated Solution # 2) was prepared by combining 10.0 grams of Concentrated Solution # 1 with a sufficient amount of a cationic polymerization modifier, to achieve a modifier of 1.13 x 10-4 moles per 10.0 grams of Concentrated Solution # 1 . A total of 22 solutions were prepared, each with a different cationic polymerization modifier. The following cationic polymerization modifiers were used: Then three experimental samples were prepared for each cationic polymerization modifier, combining enough Concentrate # 1 and Concentrated Solution # 2 to obtain samples having a modifier concentration of 1.4 x 10"6 moles / gram (prepared by combining 3.5 g of Solution) Concentrate # 1 and 0.5 grams of Concentrated Solution # 2), 2.8 x 10 ~ 6 moles / gram (prepared by combining 3.0 grams of Concentrated Solution # 1 and 1.0 g of Concentrated Solution # 2), and 5.6 x 10"6 moles / gram (prepared by combining 2.0 grams of Concentrated Solution No. 1 and 2.0 grams of Concentrated Solution # 2), respectively. A control sample consisting of 100% Concentrated Solution # 1 was also prepared. The polymerization behavior of each sample was examined using differential scanning photocalorimetry ("Photo DSC"). The equipment used was a DSCS Double Signs photo of TA Instruments, Model 2920, with a cured resin reference of 10 milligrams. The light source was a mercury / argon lamp with a 425 nm long-pass light filter, Oriel, Part No. 59480 luminous intensity can 3mW / cm2, measured using an International Light photometer, Model IL 1400 equipped with a 340A detector, XRL model. A sample dish, made of aluminum, was prepared using 10 milligrams of each sample. The temperature of the samples was then raised to 37 ° C and maintained at that temperature for one minute. Subsequently, the opening for light entry was opened, in order to irradiate the sample. During the irradiation the temperature of the samples was maintained at 37 ° C.

The total irradiation time was 30 minutes. After 30 minutes the opening was closed and the sample was maintained at 37 ° C for an additional minute. Data were collected such as heat production per unit weight (m W / g). The data was analyzed using the set of computer programs called Thermal Solutions Universal Analysis of TA. The following parameters were determined for each sample: Ti (induction period for acrylate initiation); T3 (induction period for the initiation of the epoxy); - T4 (time to reach the maximum peak for the polymerization of the epoxy); Exotherm associated with epoxy polymerization (J / g). DSC photo analysis was also performed on the control sample that lacked a cationic polymerization modifier. The induction period for the initiation of the epoxy was measured and designated as T2. The value of T2 was 1.93 minutes. The difference between T2 and T3 was then calculated for each sample prepared with a cationic polymerization modifier, to determine the effect of the modifier on the extension of the epoxy induction period. The exotherm of the control sample was also determined. Its value was 227.9 J / g. It was then compared with the exotherm of the samples containing the cationic polymerization modifier. If the value of the exotherm of the sample containing the modifier was at least 5% of the value of the exotherm of the control sample, it was determined that the polymerization of the epoxy was an exorbitant polymerization. The results of these experiments are presented in Table I. All concentrations of the modifier are given as modifier moles per 10 ~ 6 / g resin. All values of the induction period are given in minutes. All the values of the exotherm are given in J / g. The asterisks associated with Example 4 (modifier concentration = 5.6 x 10"6 moles / gram of resin) and Example 20 (modifier concentration = 5.6 x 10 ~ 6 moles / gram of resin) reflect the fact that the peak maximum for the polymerization of the epoxy was not observed in the time scale used for the experiment (ie 30 minutes) With respect to the remaining samples, the results show that, with two exceptions (example 7 / modifier concent = 1.4 x 10 ~ 6 moles / gram of resin and example 8 / concentration of modifier = 1.4 x 10"6 moles / gram of resin), each cationic polymerization initiator, at the concentrations tested, extended the period of time for initiation epoxy, cationic, as evidenced by the fact that the T3 values were higher than those of T2, without unacceptably eliminating the epoxy polymerization reaction, which was evidenced by the fact that the value of the exotherm for each sample was greater than 5% of the corresponding value for the control sample. The relatively low T3 values for the samples of Example 7 and Example 8, mentioned above, reflect the fact that the epoxy initiation occurred relatively soon after initiation. However, the T -T3 values, calculated for these two samples previously analyzed, show that, once started, the speed of epoxy polymerization was relatively slow. The difference between T4 and T3 reflects the speed with which the epoxy polymerization is carried out. The smaller the difference, the faster the polymerization. This difference was determined for both the samples containing the modifier and the control sample. In the case of the latter, the difference between T4 and T2 was determined and found to have a value of 4.86. As shown in Table I, some of the samples exhibited differences that were less than the difference exhibited by the control sample, indicating that once initiated, the epoxy polymerization of these samples is carried out faster than the of the control sample.

TABLE I TABLE I (Cont.) Examples 22-24 and Control The procedure of Examples 1-21 was followed except that samples of filled composite were analyzed. In addition, a concentrated solution (Concentrated Solution # 3) having modifier concentrations two times greater than the amounts used in Concentrated Solution # 2, was used to prepare samples for analysis. Three different modifiers were analyzed: 2- (methylamino) ethanol (example 22), t r ime t i 1 - 1, 3 -pr opandiamine (example 23), and t -but ildime t i 1 aniline (example 24). Then four experimental samples were prepared for each cationic polymerization modifier, combining sufficient quantities of Concentrate Solution # 1 and Concentrated Solution # 3 to obtain samples having a modifier concentration of 2.8 x 10"6 moles / gram (prepared by combining 3.5 gram of Concentrated Solution # 1 and 0.5 gram of Concentrated Solution # 2), 5.6 x 10"6 moles / gram (prepared by combining 3.0 grams of Concentrated Solution # 1 and 1.0 grams of Solution Concentrated # 2 11.26 x 10 -6 mol / gram (prepared by combining 2.0 grams of Concentrated Solution # 1 and 2.0 grams of Concentrated Solution # 2), and 22.4 x 10 ~ 6 moles / gram (prepared by combining 0.0 grams of Concentrated Solution # 1 and 4.0 grams of Concentrated Solution # 2), respectively . A control sample consisting of 100% Concentrated Solution # 1 was also prepared. Each sample, including the control sample, was then combined with a sufficient amount of quartz filling material treated with epoxysilane to create a filler paste having 84% by weight filler and 16% by weight resin. The samples were then subjected to Photo DSC as described above. The results are presented in table II. The designation "###" means that measurable epoxy polymerization could not be detected within the time period of the analysis (ie, 30 minutes), suggesting that the modifier concentration was so high that it suppressed the polymerization of the epoxy, instead just delay it. For the purpose of comparison, the control sample exhibited a T2 value of 2.99, a T4 value of 6.37, and an exotherm value of 58.99 J / g. The difference between T and T2, which reflects the speed of polymerization for the control sample, was 3.38. The results shown in Table II show that both the identity of the modifier and its concentration,. they are important with respect to the modifier's ability to retard the initiation of epoxy polymerization, without totally suppressing polymerization.

TABLE X Examples 25-26 and Control Two sets of samples were prepared following the procedure used to prepare examples 22-24. The first sample set (example 25) included three samples prepared using 2- (meth i 1 amino) -ethanol as the cationic polymerization modifier, at concentrations of 5.6 x 10"6 moles / gram of resin, 11.2 x 10 ~ 6 moles / gram of resin, and 22.4 x 10 ~ 6 moles / gram of resin The second set of samples (example 26) included three samples prepared using trimet-1, 1, 3-propanediamine as the cationic polymerization modifier, Concentration of 2.8 x 10 ~ 6 moles / gram of resin, 5.6 x 10 ~ 6 moles / gram of resin and 11.2 x 10"6 moles / gram of resin. The samples as well as the control sample were subsequently subjected to Photo DSC as described above. The results are presented in figure 1 (example 25) and figure 2 (example 26). Referring to Figure 1, two distinct peaks were observed, with the exception of the sample containing the highest concentration of the modifier (22.4 x 10"6 moles / gram of resin) First the initiation of the acrylate polymerization occurred. The induction period for the acrylate polymerization was short and relatively unchanged regardless of the concentration of the modifier., at modifier concentrations of 5.6 x _ 10 ~ 6 moles / gram of resin and 11.2 x 10"6 moles / gram of resin, the period of induction of epoxy was clearly lengthened in relation to the control sample. In each case, the epoxy polymerization proceeded successfully once it was started, in addition, the speed of the epoxy polymerization was greater than the speed of the control sample, which was evidenced by the fact that the peak of the exotherm of the epoxy fu .e narrower for the samples containing the modifier, relative to the control sample; the effect was particularly pronounced in the case of the sample containing 5.6 x 10 ~ 6 moles / gram of resin. Once the modifier concentration reached 22.4 10 -6 gram / moles of resin, however, the epoxy polymerization was suppressed which was evidenced by the fact of a detectable epoxy peak. Similar effects were observed in the Fig. 2 in the case of example 26. Samples containing 2.8 x 10 ~ 6 gram / moles of resin and 5.6 x 10"6 grams / moles of resin, exhibited longer induction periods, for the polymerization of epoxy relative to the control sample, while the acrylate polymerization was relatively unaffected The resin sample of 2.8 x 10"6 gram / moles also exhibited a faster epoxy polymerization than the control sample, which was evidenced by the peak more narrow. At a modifier concentration of 11.2 x 10"6 gram / mole of resin, the epoxy polymerization was suppressed, which was evidenced by the lack of a detectable epoxy peak.

Examples 27-30 These examples describe polymerized epoxy and acrylate mixtures using a double irradiation process. Four resin solutions were prepared by combining various amounts of camphorquinone (CPQ), hexafluoroantimoniat or diaryliodonium (CD1012), and t-buty Idime ti 1 aniline (tBDMA) with diepoxide resin ciel oal i fát i ca ÜVR 6105 (7.6% by weight), p-THF-250 (18% by weight), and Ebecryl 1830 acrylate oligomer (8% by weight) and stirring until a homogenous mixture was obtained, under conditions of safe light. The amounts of CPQ, CD1012, and tBDMA for each example, were as follows (all amounts are in% by weight): Each sample was placed on a polyester film and then irradiated using a curing light Model 5530 AAWZ, of 3M, which had a light guide of 12 millimeters. The distance between the curing light and the sample was 1 centimeter. Each sample was irradiated for 10 seconds and then analyzed for handling characteristics. Then each sample was allowed to stand for 5 minutes and then re-evaluated, after which each sample was irradiated until a hard solid formed. All the samples remained relatively soft and manipulable after periods of 10 seconds and 5 minutes followed by the first irradiation and formed hard solids followed by the second irradiation.

Example 31 This example describes the polymerization of an epoxy / methacrylate composition using an oxidation reduction initiation system (benzoyl peroxide plus dimethylaminfenet anol ("DMAPE")) to initiate the free radical polymerization of the acrylate and an iodonium salt to initiate the cationic polymerization of the epoxy. A concentrated solution ("Concentrated solution # 4") was prepared by combining 0.1 grams of camphorquinone (COQ), 0.3 grams of hexafluoroant imoniat or of diary lyodoni or (CD1012), 18.0 grams of diepoxide resin ci c loal i fa ti ca UVR 6105 , and 2 grams of Ebecryl 1830 acrylate oligomer, with stirring until the mixture became homogeneous, under safe light conditions. Then 9.94 grams of Concentrated Solution # 4 was combined with 0.03 grams of ethyl dimethylaminobenzoate ("EDMAB") and .0.0 grams of DMAPE to create the Coentered Solution # 5. 9.90 grams of Concentrated Solution # 4 was combined with 0.10 grams of benzoyl peroxide to create Concentrate Solution # 6. 0.50 milliliters of Concentrated Solution # 5 and 0.50 milliliters of Concentrated Solution # 6 were combined in a glass vial and thoroughly mixed in a dark room. After 7.5 minutes the mass had solidified to form a gelatinous solid, reflecting the polymerization of the Ebecryl 1830 acrylate oligomer. The gelled material was then exposed to light from a dental cure light called 3M Visilux 2, commercially available from 3M Company of St. Paul, MN, to initiate epoxy polymerization. After a 50-second exposure the material behaved exothermically and formed a hard solid. In a second experiment, the gelled material was not exposed to Visilux light. In the absence of exposure the material remained gelled (ie, did not form a hard solid) for a prolonged period of time, reflecting the absence of any measurable epoxy polymerization. Other modalities are found within the following claims. For example, the polymerizable compositions, described above, can be provided on a substrate. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (14)

REVINDICAT IONS

1. A photopolymerizable composition, characterized in that it comprises: (a) a cationically active functional group; (b) an active functional group by free radicals; and (c) a photoinitiation system capable of initiating, at a reaction temperature of less than about 40 ° C, free radical polymerization of the active functional group by free radicals, after a period of finite Ti induction and cationic polymerization. of the cationically active functional group, after a finite induction period T3, where T3 is greater than Ti. the photoinitiation system comprises: (i) a source of species capable of initiating the free-radical polymerization of the functional group by free radicals and the cationic polymerization of the cationically active functional group; and (ii) a cationic polymerization modifier, wherein, in the absence of that modifier, the cationic polymerization of the cationically active functional group is initiated under the same irradiation conditions, at the end of a finite induction period T2, wherein T2 is smaller than T3.

2. A photopolymerizable composition according to claim 1, characterized in that the composition is a photopolymerizable dental composition.

3. A photopolymerizable composition according to claim 1 or 2, characterized in that the source comprises an onium salt.

4. A photopolymerizable composition according to claim 1 or 2, characterized in that the photoinitiator system has a photoinduced potential lower than that of 3-dimethylaminoben z oi co acid in a standard solution of 2.9 x 10"5 _ moles / gram of hexaf luor oant imoniat or diphenyliodonium and 1.5 x 10 ~ 5 moles / gram of canfin orquinone in 2-butanone.

5. A photopolymerizable composition according to claim 1 or 2, characterized in that the modifier has a pKb value, measured in aqueous solution, not greater than 10.

6. A photopolymerizable composition according to claim 1 or 2, characterized in that the modifier comprises an aromatic mine, an aliphatic amine, an aliphatic amide, an aliphatic urea, a phosphine, a salt of an organic or inorganic acid, or a salt of sulfinic acid.

7. A photopolymerizable composition according to claim 1 or 2, characterized in that the photoinitiation system further comprises a photosensitizer.

8. A photopolymerizable composition according to claim 1 or 2, characterized in that the composition comprises (a). an epoxy resin having a cationically active functional group or a vinyl ether resin having a cationically active functional group; and (b) an ethylenically unsaturated compound having an active functional group by free radicals selected from the group consisting of an acid ester acrylic, an ester of methacrylic acid, and combinations thereof.

9. A photopolymerizable composition according to claim 1 or 2, characterized in that the composition comprises a polymerizable component containing a cationically active functional group and a functional group by free radicals.

10. A photopolymerizable composition according to claim 1 or 2, characterized in that it also comprises a polyol.

11. A method for polymerizing a composition, the method is characterized in that it comprises exposing a photopolymerizable composition, to a source of actinic radiation, at a reaction temperature, the photopolymerizable composition comprising: (a) a cationically active functional group, (b) a group functional active by free radicals; and (c) a photoinitiation system capable of initiating, at that reaction temperature, the free-radical polymerization of the active functional group by free radicals, after a period of finite induction and the cationic polymerization of the cationically active functional group, then of a finite induction period T3, where T3 is greater than Ti, the photoinitiation system comprises: (i) a source of species capable of initiating free radical polymerization, of the active functional group by free radicals, and polymerization cationic of the cationically active functional group; and (ii) a cationic polymerization modifier, wherein, in the absence of the modifier, the cationic polymerization of the cationically active functional group is initiated under the same irradiation conditions at the end of the finite induction period T2 / where T2 is less what T3.

12. A method according to claim 11, characterized in that the composition is a fotopol imereldable dental composition.

13. A method according to claim 12 or 13, characterized in that it comprises: (a) exposing the photopolymerizable composition at a first reaction temperature, to a first dose of actinic radiation, to initiate the polymerization of the active functional group by free radicals, then of a finite induction period i; and (b) after exposing the photopolymerizable composition at a second reaction temperature, to a second dose of actinic radiation, initiating the polymerization of the cationically active functional group, after a period of finite induction T3.

14. A method for preparing a polymerized dental composition, the method is characterized in that it comprises: (a) providing a polymerizable dental composition comprising: (i) a cationically active functional group; (ii) an active functional group by free radicals; (iii) a first initiation system capable of initiating the free-radical polymerization of the active functional group by free radicals, at a first reaction temperature of less than 40 ° C; and (iv) a second initiation system different from the first initiation system, which is capable of initiating the photoinduced cationic polymerization of the cationically active functional group, at a second reaction temperature of less than 40 ° C; (b) applying the composition to a surface; (c) inducing the polymerization of the active functional group by free radicals, at the first reaction temperature; and (d) after exposing the composition to actinic radiation, at the second reaction temperature, causing the polymerization of the cationically active functional group.