LU87512A1 - ADHESIVE COMPOSITIONS BASED ON PHOSPHORIC ESTER - Google Patents

Description

The present invention relates to adhesive compositions and relates, in particular, to polymerizable compositions capable of strongly adhering to hard, rigid body tissue, such as teeth and bones. The compositions of the invention can be used as fillings to which can be applied filling compositions for dental restoration and as priming compositions to which dental adhesives can be applied with a view to the installation, for example, of hooks orthodontics or crowns. The present invention therefore also relates to the use of new compositions as priming compositions in dentistry for the purposes of restoration, adhesion, or modification of the position of teeth.

Amalgam and filling compositions for dental restoration do not adhere properly to the surface of the teeth. In filling a dental cavity, the problem of poor adhesion can be alleviated by preparing cavities so as to improve the mechanical retention of the filling filler. In the case of the enamel surface, the mechanical bond can be improved on a microscopic scale by corrosive attack on the surface with phosphoric acid. However, a system involving genuine adherence would allow the dentist to improve the operating procedures. The use of phosphoric acid could be greatly reduced or even eliminated in some cases; restoration methods involving dentin removal could be implemented with a sharp reduction in the rate of removal of vital tissue; marginal leakage could be reduced.

We must not lose sight of the fact that an adhesive system is associated with bones and teeth which are real materials, that is to say that it is associated with a living dynamic tissue, and as such, any membership is likely to be the result of a compromise between competing influences. For example, to adhere to the surface of a tooth, the presence of hydrophilic groups is necessary, but their presence increases the likelihood that the adhesive will be unstable on hydrolysis. However, the practitioner has a certain number of adhesives, some of which are based on organic phosphoric esters. It is therefore very desirable that the active adhesive component has a low concentration in the adhesive composition and, therefore, this component must have pronounced adhesive properties. The composition should be low in viscosity so that it flows easily over the surface to be bonded.

European Patent No. 0 074 708 discusses a considerable number of patents in which various phosphorated ethylenically unsaturated esters are described as adhesives. In the aforementioned patent, specific phosphoric esters based on a long-chain alkyl ester of acrylic and methacrylic acids are mentioned, and it is stated that these esters exert very good adhesive properties in dental applications. This document mentions that 2-methacryloylloxyethyl dihydrogen phosphate is a relatively poor adhesive component and that it produces the blistering of a paint film. European patent application No. 0 115 948 describes the use of organic pyrophosphoric esters as polymerizable components of adhesives. European patent applications Nos. 0 058 483 and 0 132 318 describe the use of esters of halophosphorus acids as polymerizable monomers in an adhesive for dental use; these esters contain at least one ethylenically unsaturated functional group and a chlorine or bromine atom attached directly to the phosphorus atom.

U.S. Patent 4,044,044 describes the use of phosphoric esters of hydroxyacrylates as components of anaerobic adhesive compositions. These compositions are considered to remain in the liquid state as long as they remain in contact with air, while it is mentioned that they quickly set by polymerization in the absence of air. These adhesive compositions are useful as materials preventing loosening, in particular under high pressure.

The Applicant has just found that the adhesive properties linked to polymerizable esters of a phosphorus acid depended not only on the degree of impurity of the particular ester, but also on the inclusion of a small quantity of a relatively fine filler. .

According to the present invention, there is provided a single-component liquid adhesive composition, curable in visible light, which comprises: (a) 2 to 20 parts by weight of at least one practically pure phosphoric ester corresponding to the formula CH2 = C (R-1-) .C0.0.r2.0P (0) (OH) 2 in which R · * - is a hydrogen atom or a methyl group and R2 is a group -CH2-CH2-, -CH2-CH (CH3) - or -CH (CH3) -CH2- and (b) 98 to 80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphoric ester, and (c) 1 at 9% by weight, on the basis of a + b, of at least one inorganic filler in particles of diameter less than 0.1 μιη, and an effective amount of a catalyst activated by visible light.

The phosphorus ester component present in the compositions of the invention is preferably 2-methacryloyloxypropyl dihydro-genophosphate. The phosphoric esters used in the compositions of the present invention can be prepared for example by reaction of a hydroxyalkyl acrylate (or methacrylate) with at least an equimolar amount of phosphorus oxychloride in the presence of a tertiary amine, followed by hydrolysis of any remaining chlorine-phosphorus bonds. The dihydrogen phosphorus ester is then purified by a series of washing and extraction operations so that the ester is practically pure, that is to say free of other esters of phosphorus acid, so that the impurity level is less than 5% by weight and preferably less than 2% by weight.

The adhesive compositions of the present invention contain at least one ethylenically unsaturated monomer copolymerizable with the phosphoric ester. The most frequently used monomers include those of the (meth) acrylate, vinyl urethane and styrene types, and vinyl acetate. However, other monomers such as (meth) acrylamides, vinyl ethers, fumarates, maleates, vinyl ketones, vinyl nitriles, vinylpyridines and vinylnaphthalenes can also be used, alone or in combination, at the moment that the viscosity parameter of the composition is satisfied. The concentration of the phosphoric ester in the adhesive composition is preferably equal to or greater than 5 parts by weight and it is preferable that it does not exceed 15 parts by weight.

Advantageous vinyl esters for use in the process of the invention include, for example, vinyl acetate and acrylic acid esters of the formula CH2 = CH-COOR3, wherein R3 is an alkyl, aryl, alkaryl group , aralkyl or cycloalkyl. For example, R3 can be an alkyl group having 1 to 20 and preferably 1 to 10 carbon atoms. Particular vinyl esters which may be mentioned include, for example, methyl acrylate, ethyl acrylate, n-propyl and isopropyl acrylates and n-butyl, isobutyl and tert-butyl acrylates .

Other suitable vinyl esters include, for example, esters of formula CH2 = C (R4) COOR3 in which R4 is a methyl radical. In the ester of formula CH2 = C (R4) COOR3 R3 and R4 may be the same or different.

Particular vinyl esters which may be mentioned include, for example, methyl methacrylate, ethyl methacrylate, n-propyl and isopropyl methacrylates and n-butyl, isobutyl and tert-butyl methacrylates , and vinyl esters such as n-hexyl, cyclohexyl and tetrahydrofurfuryl acrylates and methacrylates. The monomers must have low toxicity. Suitable aromatic vinyl compounds of the styrene type include, for example, styrene and its derivatives, for example α-alkyl derivatives of styrene such as α-methylstyrene and vinyltoluene.

Suitable vinyl nitriles include, for example, acrylonitrile and its derivatives, for example methacrylonitrile.

Other ethylenically unsaturated monomers which can be advantageously used include vinylpyrrolidone and hydroxyalkyl acrylates and methacrylates, for example hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

Polyfunctional monomers can also be used as polymerisable materials, i.e., monomers containing two or more of two vinyl groups. Suitable monomers include, for example, glycol dimethacrylate, diallyl phthalate and triallyl cyanurate.

The ethylenically unsaturated material may comprise at least one ethylenically unsaturated polymer, advantageously in combination with at least one ethylenically unsaturated monomer.

The composition of the invention is advantageously devoid of volatile solvent.

These polymerizable materials are preferably liquid materials with ethylenic unsaturation such as vinylurethane, for example materials described in British Patents No. 1,352,063, 1,465,097, 1,498,421 and in the Republic's patent application. Federal Republic of Germany DE-OS-2 419 887, or the reaction product of a diol such as glycol, but in particular a bisphenol, with a glycidyl alkacrylate such as those which are described for example in state patents - United States of America n ° 3 066 112 and 4 131 729 (the description of which is incorporated here for documentary purposes).

A popular reaction product between a glycidyl alkacrylate and a diol has the formula:

Preferred vinyl urethanes described in the British patents and the aforementioned DE-OS patent application include the reaction product of a urethane prepolymer and an acrylic or methacrylic acid ester with a hydroxyalkanol having at least 2 atoms carbon, the urethane prepolymer being the reaction product of a diisocyanate of formula OCN-R5-NCO and a diol of formula HO-R6-OH, in which R5 is a divalent hydrocarbyl group and is the residue d 'a condensation product of an alkylene oxide with an organic compound containing two phenolic or alcoholic groups.

Other suitable vinyl urethanes include those which are prepared by reaction of alkyl and aryl diisocyanates, preferably alkyl, with hydroxyalkyl acrylates and alkacrylates such as those described in British Patents No. 1 4 01 805, 1 428 672 and 1 430 303 (incorporated here for documentary purposes).

The dental compositions of the present invention are cured by irradiation with visible radiation, preferably those having a wavelength in the range of 400 ιημιη to 500 ιημιπ. So that the curing of the compositions can be obtained within this range, the compositions contain a catalyst which is activated by visible light. Such a catalyst preferably contains at least one ketone chosen from fluorenone and diketone and at least one organic peroxide.

Advantageous ketones for use in the composition of the present invention also of themselves produce some photosensitive catalytic effect without the presence of an organic peroxide. This activity of the ketone is promoted by the addition of a reducing agent as described in the patent application of the Federal Republic of Germany DE-OS-n ° 2 251 048. The ketones are therefore chosen in this case between fluorenone and a-diketones and their derivatives which, when mixed with a similar amount of organic amine which is capable of reducing this ketone when the latter is in an excited state but in the absence of organic peroxide, catalyze the maturation of '' an ethylenically unsaturated material. Signs of maturation can be conveniently detected by examining the change in viscosity of a mixture of ethylenically unsaturated material containing the ketone and the organic amine each in a proportion of 1% by weight based on the material to be ethylenic unsaturation using an oscillating rheometer, samples 2 mm thick, while irradiating the mixture with light of a wavelength in the range 400 to 500 ιημιη. Such an examination may be carried out by the method described in British Standard British Standard 5199: 1975, paragraph 6.4, provided that arrangements are made to allow the incidence of visible light on the mixture. Preferably, the ketone has a maturation time of less than 15 minutes for an irradiation rate of 1000 w / m2, measured at 470 ιημιη, over a bandwidth of ± 8 πιμπι, using for example a Macam radiometer ( Macam Photometries Ltd., Edinburgh, Scotland).

Diketones have the formula:

wherein the groups A, which may be the same or different, are hydrocarbyl or substituted hydrocarbyl groups and these groups A can furthermore be linked together by a divalent junction or by a hydrocarbyl or substituted hydrocarbyl group, or else the groups A can form together a condensed aromatic nucleus. The groups A are preferably the same.

The groups A can be aliphatic or aromatic. Within the definition of the term aliphatic are included cycloaliphatic groups and aliphatic groups which carry aromatic substituents, i.e. aralkyl groups. In the context of the definition of the aromatic group, groups which bear alkyl substituents, that is to say alkaryl groups, are considered. The term aromatic groups also covers heterocyclic groups.

The aromatic group may be a benzene aromatic group, for example the phenyl group, or it may be a non-benzene cyclic group which is technically recognized as having the characteristics of a benzene aromatic group.

The groups A, in particular when they are aromatic, can carry substituent groups other than hydrocarbyl groups, for example a halogen or an alkoxy group. Substituents other than hydrocarbyl groups may cause inhibition of the polymerization of ethylenically unsaturated materials, and if the a-diketone contains such substituents, it is preferable that it is not present in the photopoly- deservable at a concentration such that it results in a significant inhibition of the polymerization of the ethylenically unsaturated material in the composition.

The groups A can also be linked to each other by a direct bond or by a divalent group, for example a divalent hydrocarbyl group, that is to say in addition to the bond by the group

The groups A can also be linked so as to form a cyclic ring. For example, when groups A are aromatic, a-diketone can have the structure

in which Ph is a phenylene group, Y is a group> CH2, or a derivative of this group in which one or both of the hydrogen atoms is replaced by a hydrocarbyl group, and m has the value 0, 1 or 2. Preferably, the group Y is attached to the aromatic groups in the ortho positions.

Groups A can jointly form a system of condensed aromatic rings.

In general, α-diketones are capable of being excited by radiation in the visible region of the spectrum, that is to say by light of wavelength greater than 400 ιημιη, for example in the length range from 400 ιημπι to 500 πιμιη. For the present invention, the a-diketone must have low volatility so as to minimize the odor and the variations in concentration. Suitable α-diketones include benzile in which the two groups A are phenyl groups, a-diketones in which the two groups A are condensed aromatic rings, for example a-naphthile and beta-naphthile and α -diketones whose groups A are alkaryl groups, for example p-tolile. As an example of a suitable a-diketone, the groups A of which are non-benzene aromatics, mention may be made of a furile, for example 2: 2'-furile. A-diketone derivatives in which the groups A carry non-hydrocarbyl groups such as, for example, a p, p'-dialkoxy-benzile, for example ρ, ρ'-dimethoxybenzile or a p, p'- dihalobenzile, for example p, p'-dichlorobenzile, or p-nitrobenzile can be incorporated.

Groups A can be linked to each other by a single bond or by a divalent hydrocarbyl group to form a cyclic ring. For example, when the groups A are aliphatic, the α-diketone can be camphoquinone.

An example of a-diketone of formula I is phenanthraquinone in which the aromatic groups A are attached by a single bond in ortho to the group

Suitable derivatives include 2-bromo-, 2-nitro, 4-nitro, 3-chloro-, 2,7-dinitro, 1-methyl-7-isopropylphenanthraquinone.

The α-diketone can be acenaphthenequinone in which the groups A together form a system of condensed aromatic rings.

The ketone can also be fluorenone and its derivatives such as, for example, lower alkyl derivatives (C1 to C6), halogenated, nitrated, carboxylic acid derivatives and their esters, in particular in positions 2 and 4.

The ketone may, for example, be present in the composition at a concentration in the range of 0.01% to 2% by weight of the polymerizable material in the composition, although concentrations deviating from this range may be used where appropriate. The ketone is advantageously present at a concentration of 0.1 to 1% and in particular 0.5 to 1% by weight of the ethylenically unsaturated material in the composition. The ketone must be soluble in the polymerizable material and the above concentrations refer to the concentration in solution.

The organic peroxides which can be advantageously used in the composition of the invention include those which correspond to the formula R7 - 0 - O - R7 in which the groups R7, which may be identical or different, represent hydrogen or alkyl groups , aryl or acyl, not more than one of the R groups representing hydrogen. The term acyl means a group of formula R8 - CO - in which R8 is an alkyl, aryl, alkoxy or aryloxy group. The terms alkyl and aryl have the definitions given above for groups A and include substituted alkyl and aryl groups.

Examples of organic peroxides which can be used in the composition of the present invention include diacetyl peroxide, dibenzoyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, tert-butyl perbenzoate, perdicar- di-tertio-butyl-cyclohexyl bonate.

The organic peroxide may, for example, be present in the composition in the range of 0.1 to 10% by weight of the polymerizable material in the composition, although a concentration deviating from this range may be used where appropriate. .

The reactivity of a peroxide is often measured by the half-life temperature of ten hours, that is to say that in ten hours at this temperature, half of the oxygen has been made available. The peroxides present in the compositions of the invention preferably have ten hour half-life temperatures of less than 150 ° C and preferably less than 100 ° C.

The speed at which the composition of the invention matures under the influence of visible light can be accelerated by the incorporation into the composition of a reducing agent at a concentration of 0.1 to 10% by weight of the polymerizable material. , which is able to reduce the ketone when it is in an excited state. Suitable reducing agents are described, for example, in the patent application of the Federal Republic of Germany DE-OS-2 251 048 and include organic amines, phosphites, sulfuric acids.

In general, non-basic reducing agents are preferable because they are capable of reacting with the phosphoric ester. Suitable non-basic reducing agents include aldehydes and organic tin compounds having the formula: (R9) n Sn (OR10) m where n and m are whole numbers 1, 2 or 3 and the sum n + m = 4, R9 is an alkyl or alkenyl group containing 1 to 18 carbon atoms and R10 represents R9 or a group R9.CO- or a group of formula ([R9] 3Sn) 20

The filler is present in an amount of 1 to 9% by weight of the composition, preferably 4 to 6%. The filler is any form of silica, including divided forms of crystalline silica, for example sand, but it is preferably in a colloidal form such as silica formed by pyrogenation or precipitated.

The components can be mixed by stirring the polymerizable material and the filler together. It may be useful to first dissolve the catalyst components in the polymerizable material; the latter can conveniently, but less advantageously, be diluted with a suitable diluent so as to improve the dissolution of the components of the catalyst. When mixing has been carried out, the diluent can be removed if necessary, for example by evaporation. The composition of the invention is advantageously almost devoid of solvent, because its presence can hinder adhesion and can cause toxicity problems.

Since the photo-sensitive catalyst makes the polymerizable material and the monomer sensitive to light in the visible range of 400 to 500 μm, this part of the preparation of the composition of the invention in which the photo-sensitive catalyst is added and subsequent handling, for example packaging in a container, must be carried out essentially away from light entering this range. The preparation can very advantageously be carried out by using light outside this range, for example with the light emitted by electric discharge lamps in sodium vapor.

According to another embodiment of the present invention, there is provided a maturation process which consists in irradiating the composition of the invention with visible radiation having a wavelength between 4 00 and 500 ιημιη. The process can be carried out at any suitable temperature, provided that the composition does not crystallize and does not fragment, in which case the temperature is too low, or does not undesirably volatilize, in which case the temperature is too high. The process is preferably carried out at ambient temperatures, that is to say between 15 "C and 40 ° C.

It is envisaged to coat the surface of a tooth with the composition of the invention which is then made to mature under a visible light source; the composition is advantageously matured using a portable light source. However, it is preferable that the surface of the tooth is primed before being so coated; a primer which is preferred is a bisbiguanide, a polybiguanide or a long chain quaternary salt as described in British patent application No. 8,810,412.

A dental composition according to the present invention is advantageously packaged in small individual containers (for example with a capacity of 10 g) so as to facilitate surgical handling and to reduce the risk of inadvertent maturation, for example under the effect of scattered light.

For aesthetic purposes, such a dental composition can take on the appearance of a tinted, colored or natural tooth and, consequently, the composition of the invention can contain small amounts of pigments, opalescent agents, etc. The composition may also contain small amounts of other materials such as antioxidants and stabilizers, as long as they do not significantly affect the ripening.

The invention is illustrated by the following examples:

Example 1 (a) Preparation of a phosphoric ester

Phosphorus oxychloride (127.9 g; 0.83 mole) was mixed with methylene chloride (600 cm3). The mixture was stirred and cooled to 0 ° C. A mixture of hydroxypropyl methacrylate (120 g; 0.83 mole), pyridine (65.8 g; 0.83 mole) and methylene chloride (400 cm3) was added dropwise to the mixture containing the phosphorus oxychloride over a period of 45 minutes while maintaining the reaction temperature in the range of 0 to 3 ° C. The mixture was stirred for a further 2 hours over this temperature range. The reaction mixture was then poured into 1 liter of cold water and the chloromethylenic phase was separated and washed twice with water. The chloromethylenic solution was then mixed with water and the methylene chloride was removed on a rotary evaporator leaving an aqueous phase and a small amount of inorganic material insoluble in water. The aqueous phase was washed twice with methylene chloride and then acidified carefully (hydrochloric acid 208 cm3) with stirring. The aqueous phase was then extracted with ethyl acetate (1 liter) and the new aqueous phase was discarded. The phosphoric ester concentration was then estimated and analyzed by acid-base titration methods and it was found that the product contained less than 2% by weight of 2-methacryloyloxypropyl dihydrogen phosphate ester as an impurity. Triethyleneglycol dimethacrylate (TEGDM) was then added to obtain a TEGDM: phosphate mixture at 90:10. The ethyl acetate was then removed on a rotary evaporator at 65 ° C and under a vacuum of 6.67 kPa.

(b) Several formulations were prepared having a filler concentration and a composition as indicated in Table 1. The catalyst components were added to the monomer mixture as follows:% w / w

Camphoquinone 0.73

Dibutyltin dilaurate 0.49 "Topanol" 0 amount sufficient for 200 mg / kg compared to the final composition "Aerosil" A130 variable amount

This addition and the subsequent operations of using the composition were carried out in the light of a discharge in sodium vapor.

The evaluation of the adhesion strength on samples having the above formulations was carried out using the methods described in the

British Dental Journal 1984, pages 93 to 95, except that the composite restorative material used in conjunction with the adhesive composition consisted of "Occlusin" (trademark of Imperial Chemical Industries PLC). The surface of the dentin was brushed with "Vantocil" solution (0.1% by weight in water), the operation being followed by drying under a stream of air, before the formulation was applied . The product "Vantocil" is a polybiguanide corresponding to the formula {(CH2) 6 "NH.C (: NH) .NH.C (: NH) NHtn in which na has a value of 4 to 7." Vantocil "is a brand commercial of Imperial Chemical Industries PLC. The samples were ripened by radiation emitted by a halogen lamp with tungsten filament having a tuned reflector and a dichroic filter eliminating ultraviolet rays; the intensity was 1000 Wm-2 and the maturation time was 30 seconds.

"Topanol" is a trademark of the

Firm Imperial Chemical Industries PLC and "Topanol" O denotes 2,6-ditertiobutyl-4-methylphenol.

"Aerosil" is a trademark of the

Degussa AG; "Aerosil" A130 is a hydrophilic quality of silica in impalpable particles with an average diameter of 0.02 μιη.

TABLE 1

Load,% Binding force (MPa) 0 7.0 5 13.0 7.5 11.0 10 7.0

The above results are reproduced in the single figure of the accompanying drawing.

Example 2

A similar bond strength was obtained using an adhesive of the following composition:% by weight

Phosphoric ester (as described in Example 1) 9.48 Vinyl urethane resin * 15.17 TEGDM 70.16

Camphoquinone 0.71

Dibutyltin dilaurate 0.48 "Aerosil" A130 4.00 * As described in Example 1 of European Patent No. 59,649.

The vinylurethane resin and the phosphoric ester are incorporated in the form of solutions in the TEGDM, the amount of TEGDM thus added being included in the total content of TEGDM.

Claims (10)

1. Liquid adhesive composition with a single component, which can be matured in visible light, characterized in that it comprises: (a) 2 to 20 parts by weight of at least one practically pure phosphoric ester corresponding to the formula CH2 = C ( R1). CO.O.R2.0P (0) (OH) 2 in which R1 is a hydrogen atom or a methyl group and R2 is a group -CH2-ch2 -, - ch2-ch (ch3) - or -ch ( ch3) -ch2- and (b) 98 to 80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphoric ester, and (c) 1 to 9% by weight of a fine inorganic filler and an effective amount of a catalyst activated by visible light. 2. Composition according to claim 1, in which the phosphoric ester corresponds to the formula CH2 = C (CH2) .C0.0.R2.0P (0) (OH) 2 in which R2 is an isopropylene group. 3. Composition according to one of claims 1 and 2, characterized in that the concentration of the phosphoric ester is 5 to 15 parts by weight. 4. Composition according to any one of claims 1 to 3, in which the ethylenically unsaturated monomer comprises a glycol dimethacrylate. 5. Composition according to claim 4, characterized in that the monomer also comprises a vinylurethane. 6. Composition according to any one of claims 1 to 5, characterized in that the filler weight present is in the range of 4 to 6%. 7. Composition according to any one of claims 1 to 6, characterized in that the filler consists of colloidal silica. 8. Composition according to any one of claims 1 to 7, characterized in that the catalyst activated by visible light comprises camphoquinone and a reducing agent. 9. Composition according to claim 8, characterized in that 11 reducing agent is an organic tin compound of formula (R9) nSn (OR10) m in which n and m are whole numbers having the value 1, 2 or 3 and the sum n + m is equal to 4, R9 is an alkyl or alkenyl group containing 1 to 18 carbon atoms and R10 represents R9 or a group R9CO-. 10. Composition according to claim 8, characterized in that the reducing agent is an organic tin compound of formula ([R9] 3Sn) in which R9 is an alkyl or alkenyl group containing 1 to 18 carbon atoms.