NL8702561A - ADHESIVE PREPARATIONS. - Google Patents

Abstract

A single-component, visible light-curable liquid adhesive composition having a viscosity of less than 25 centipoise at 25 DEG C which comprises (a) 2 to 20 parts by weight of at least one substantially pure phosphate ester having the formula CH2=C(R<1>).CO.O.R<2>.OP(O)(OH)<2> in which R<1> is a hydrogen atom or a methyl group, and R<2> is -CH2-CH2-, -CH2-CH(CH3)- or -CH(CH3)-CH2- and (b) 98 to 80 parts by weight of at least one ethylenically unsaturated monomer copolymerisable with the phosphate ester, and an effective amount of a visible light activated catalyst. The compositions may be used as liners in dental restorations and as primers for adhesives for orthodontic brackets and crowns.

Description

“17λ) ..7

Adhesive preparations.

The invention relates to adhesive preparations and in particular to polymerizable preparations which can adhere strongly to rigid hard tissues in the body such as teeth and bones. The compositions according to the invention can be used as liners to which dental filler compositions can be applied and as primers to which adhesives used in dentistry can be applied for mounting, for example, orthodontic bridges, brackets or crowns.

The invention therefore also relates to the use of the present compositions as base layers or base materials for restoring, adhering to or changing the position of teeth.

Amalgam and restorative dental filler materials do not adhere very well to dental surfaces. When filling a cavity in a tooth, the problem of poor adhesion can be improved by forming a cavity with undercut edges to improve the mechanical retention of the filling. In the case of enamel surfaces 20, the mechanical anchoring can be improved on a small scale by etching the surface with phosphoric acid. But a true adhesive system would allow the dentist to improve methods of tooth repair. The use of phosphoric acid could be greatly reduced or even eliminated in some cases; restorations involving dentin removal could be performed with much less vital tissue removal; leakages around edges could be reduced.

30 It should be remembered that an adhesive system associated with bones and teeth is a real material, ie it is associated with living, dynamic tissue and as such any adhesive or adhesive is likely to result from a compromise 35 between conflicting influences. For example, to adhere 8702561 w - 2 - to the surface of a tooth requires hydrophilic groups, but their presence increases the likelihood that the adhesive or adhesive will be hydrolytically unstable. Nevertheless, a number of adhesives or adhesives 5 are available to the dentist, almost all of which are formulated on the basis of organic phosphate esters. Therefore, it is particularly desirable that the active adhesive component in the adhesive or adhesive composition has a low concentration and thus should have strong adhesive properties. The preparation should have a low viscosity so that it easily flows over the surface to be bonded (must be adhered).

European patent application 0 074 708 discusses a considerable number of patent applications in which 15 different ethylenically unsaturated phosphorus esters are described as adhesives. In that patent application certain phosphate esters based on an alkyl ester of acrylic acid and / or long-chain methacrylic acid are described which are said to have improved bonding properties in applications in dentistry. In that patent application it is stated that 2-methacryloyloxyethyl dihydrogen phosphate is a relatively poor adhesive component and leads to flaking in a paint layer. European patent application 0 115 948 describes the use of organic pyrophosphate esters as polymerizable adhesive components. European patent applications 0 058 483 and 0 132 318 describe the use of halophosphoric acid esters as polymerizable monomers in an adhesive for dental purposes; these esters contain at least one ethylenically unsaturated functional group and a chlorine or bromine atom bonded directly to the phosphorus atom.

U.S. Patent 4,044,044 describes the use of phosphate esters of hydroxy acrylates as components of anaerobic adhesive compositions. These adhesive formulations are said to remain liquid as long as they remain in contact with air while rapidly curing by air exclusion polymerization. Those adhesive compositions are suitable as materials that prevent peeling, especially at high pressures.

8702561 - 3 -

It has now been found that the adhesion properties are poor. linked with polymerizable esters of phosphoric acid depending on the impurity content in the respective ester; therefore, if a dihydrogen phosphate ester is substantially free of phosphoric acid, of the monohydrogen ester and of the fully esterified ester, the adhesive composition formed surprisingly is effective as an adhesive in an aqueous environment. The invention provides storage stable adhesive compositions which cure rapidly in the presence of air.

According to the invention there is provided a one-component, visible-curable liquid adhesive composition having a viscosity of less than 25 centipoises at 25 ° C, comprising (a) 2 to 20 wt. din of at least one substantially 15 pure phosphate ester of the formula CH2 = C (Rj) .CO.OR ^ .OPCO) (0H) 2> where Rj represents a hydrogen atom or a methyl group and a> -CH2-CH (CH3) - or -CH (CH3) -CH2- moiety and (b) 98 to 80 parts by weight of at least one ethylenically unsaturated monomer that can be polymerized with the phosphate ester, and an effective amount of a catalyst which is visible is activated.

The phosphorus ester component in the present compositions is preferably 2-methacryloyloxypropyl dihydrogen phosphate. The phosphate esters used in the compositions of the present invention can be prepared by reacting, for example, 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 phosphor ester is then purified in a series of washing and extraction steps so that the ester is substantially pure, that is, free from other esters of phosphoric acid, so that that impurity content is less than 5 wt% and preferably less than 2 wt% .%.

The adhesive compositions of the invention contain at least one ethylenically unsaturated monomer which is copolymerizable with the phosphate ester. The viscosity properties of the composition, such as the viscosity itself and the flow and wetting properties, are largely determined by that of the monomer. A wide variety of monomer (s) is suitable for the present compositions, provided that the viscosity of the obtained composition is less than 25 centipoises at 25 ° C. The most commonly 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, 10 maleates, vinyl ketones, vinyl nitriles, vinyl pyridines and vinyl naphthalenes can also be used either alone or in combination, provided the condition for the viscosity parameter of the composition is met. The concentration of phosphate ester in the adhesive composition is preferably. Preferably 5 wt.% Or more, and preferably not greater than 15 wt.%.

Vinyl esters suitable for use in the process of the invention include, for example, vinyl acetate and esters of acrylic acid having the structure C 1 -CH-COORg, which is an alkyl, aryl, alkaryl, aralkyl-20, or cycloalkyl group. For example, R ^ may be an alkyl group of 1 to 20 and preferably 1 to 10 carbon atoms. Specific vinyl esters which may be mentioned include, for example, methyl acrylate, ethyl acrylate, n- and isopropyl acrylates and n-, iso and tertiary butyl acrylates.

Other suitable vinyl esters include, for example, esters of the formula C 1 C 1 C 12 COORg wherein R 4 is methyl. In the ester of the formula CH2 = C (R ^) C00Rj, R ^ and R ^ may be the same or different.

Specific vinyl esters which may be mentioned include, for example, methyl methacrylate, ethyl methacrylate, n- and isopropyl methacrylate, and n-, iso and tertiary butyl methacrylate vinyl esters, such as n-hexyl, cyclohexyl and tetrahydrofurfury acrylates and methacrylates. The monomers must have low toxicity. Suitable styrene-type aromatic vinyl compounds include, for example, styrene and derivatives thereof, for example, α-alkyl derivatives of styrene, for example, α-methylstyrene and vinyl toluene.

Suitable vinyl nitriles include e.g. 8702561

V

5%, for example, acrylonitrile and derivatives thereof, for example methacrylonitrile.

Other suitable ethylenically unsaturated monomers include vinyl pyrrolidone and hydroxyalkyl acrylates and methacrylates, for example hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

Polyfunctional monomers are also suitable as polymerization materials, ie monomers containing two or more 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, suitably in combination with at least one ethylenically unsaturated monomer.

The present compositions are preferably free from volatile solvents. However, when a solvent is included, the following polymerizable materials may also be present, provided that the viscosity of the composition is less than 25 centipoises at 25 ° C.

Such polymerizable materials are preferably liquid ethylenically unsaturated materials such as vinyl urethanes, for example those disclosed in British Pat. Nos. 1,352,063, 1,465,097, 1,498,421 and in German Offenlegungsschrift 2,419,887, or the reaction product of a diol such as glycol, but in particular a bisphenol, with a glycidyl alkacrylate such as the products described in, for example, U.S. Pat. Nos. 3,0 3,066,112 and 4,131,729 (the contents of which are hereby referred by reference).

A reaction product of a glycidyl alkacrylate and a preferred diol is of the formula 1.

Preferred vinyl urethanes described in the aforementioned British Patents and German Offenlegungsschrift are the reaction product of a urethane prepolymer and an ester of acrylic acid or methacrylic acid with a hydroxyalkanol having at least two carbon atoms, the urethane prepolymer being the reaction polymer. 1 * - - 6 -

product of a diisocyanate with the structure OCN-R 2 -NCO

and a diol of the structure HO-R, -OH in which Rc is a divalent hydrocarbyl group and Rc is the residue of a condensate of an alkylene oxide with an organic compound containing two phenolic or alcoholic groups.

Other suitable vinyl urethanes include those prepared by reacting alkyl and aryl, preferably alkyl, diisocyanates with hydroxyalkyl acrylates and alkacrylates such as the products disclosed in British Patents 1,401,805, 1,428,672 and 1,430,303 ( the contents of which patents are referenced herein by reference).

The dental treatment preparations according to the invention are cured by irradiating the preparation with visible radiation, preferably with a wavelength in the range from 400 nm to 500 nm. In order to achieve curing of the preparations in that (wavelength) range, the preparations contain a catalyst which is activated by visible light. Such a catalyst preferably contains at least one ketone selected from fluorenone and diketone and at least one organic peroxide.

Ketones suitable for use in the compositions according to the invention also show a certain photosensitive catalytic action by themselves without the presence of an organic peroxide. Such an activity of the ketone is enhanced by the addition of a reducing agent, as described in German Offenlegungsschrift 2,251,048. The subject ketones are therefore selected from fluorenone and α-diketones and their derivatives which, when mixed with a corresponding amount of organic amine capable of reducing the ketone when the latter is in the excited state, but in the absence of organic peroxide, an ethylene catalyzing unsaturated material. A proof that curing occurs (has occurred) can conveniently be obtained by the change in viscosity of a mixture of the ethylenically unsaturated material containing the ketone and the organic amine, each in an amount of 1% by weight based on ethylenic unsaturated material, using an oscillating rheometer to track samples of 2 mm thick, while the mixture 8702561 * - 7 - is irradiated with light having a wavelength in the range of 400 to 500 nm. Such viscosity observation can be performed according to the method described in British Standard 5199i 1975, paragraph 6.4 provided that provision is made to allow visible light to be directed onto the mixture. Preferably, the ketone has a cure time of less than 15 minutes at a radiation level of 1000 w / m2 measured at 470 nm with a bandwidth of 8 nm, e.g. using a Macam Radiometer (Macam Photometries Ltd., Edinburgh, Scotland) .

Diketones are of the formula 2 wherein the groups A which may be the same or different are hydrocarbyl or substituted hydrocarbyl groups and wherein the groups A may be further linked together by a direct bond or by a divalent hydrocarbyl or substituted hydrocarbyl group or wherein the groups A together may form a fused aromatic ring system. Preferably, the groups A are the same.

Groups A can be aliphatic or aromatic. The term aliphatic also includes cycloaliphatic groups and aliphatic groups bearing aromatic substituents, ie aralkyl groups. Likewise, it is within the scope of the term aromatic group to include those groups which carry alkyl substituents, i.e., alkaryl groups. Heterocyclic groups also fall within the scope of the term aromatic groups.

The aromatic group can be a benzoide aromatic group, for example the phenyl group, or it can be a non-benzoide cyclic group which is recognized in the art to have the properties of a benzoide aromatic group.

The groups A, especially if aromatic, may carry substituents other than hydrocarbyl groups, for example, halogen atoms or alkoxy groups. Substituents other than hydrocarbyl groups can inhibit the polymerization of ethylenically unsaturated materials and if the α-diketone contains such substituents, it is preferably not present in the photopolymerizable composition at such a concentration that it leads to a post-35 P 7 ? 2: ·.

- 8 - e mention complete inhibition of the polymerization of the food unsaturated material in the preparation.

The groups A may further be joined together by a direct bond or by a divalent group, for example a divalent hydroxycarbyl group, ie, in addition to the bond through the group of the formula 3, the groups A may be further joined to form a cyclic ring system . For example, if groups A are aromatic, the α-diketone may have the structure of formula 4 wherein Ph represents a phenylene group, Y is a radical of the formula> CH 2 / or a derivative thereof in which one or both hydrogen atoms are replaced by a hydrocarbyl group, and wherein m is 0, 1 or 2. Preferably, the group Y is attached to the aromatic groups at ortho positions relative to the group of formula 3.

Groups A together may form a fused aromatic ring-15 system.

In general, α-diketones are capable of being excited by radiation in the visible part of the spectrum, that is, by light with a wavelength in excess of 400 nm, for example in the range from 400 nm to 500 nm. For the present invention, the α-diketone must have a low volatility to minimize odor and minimize variations in concentration. Suitable α-diketones include benzil in which both groups A are phenyl groups, α-diketones in which both groups A are fused aromatic, for example a-naphthil and β-naphthil groups, and a-dike-25 in which the groups A are alkaryl groups, for example p-tolil.

As an example of a suitable α-diketone in which the groups A are non-henzenoid aromatic groups, mention can be made of furil, for example 2.2'-furil. Derivatives of the α-diketone in which the groups A carry non-hydrocarbyl groups, such as, for example, p.p'-dialkoxybenzil, for example p.p'-dimethoxybenzil or p.p'-dihalogenbenzil, for example p.p'dichlorobenzil or p-nitrobenzil can be recorded.

Groups A may be joined together by a direct bond or by a divalent hydrocarbyl group to form a cyclic ring system.

When the groups A are aliphatic groups, the α-diketone can be 8 7 0 2 5 6 1 - 9 - for example camphorquinone.

An example of an α-diketone of the structural formula 4 is phenanthraquinone in which the aromatic groups A are linked by a direct bond ortho to the group of the formula 3. Suitable derivatives include 2-bromo, 2- nitro, 4-nitro, 3-chloro, 2,7-dinitro, 1-methyl-7-isopropylphenanthraquinone.

The α-diketone may be acenaphthenequinone in which the groups A together form a fused aromatic ring system.

The ketone may also be fluorenone or a derivative thereof, such as, for example, lower alkyl (C 1-4), halogen, nitro, carboxylic and carboxylic acid ester derivatives, especially in the 2 and 4 positions.

For example, the ketone may be present in the composition at a concentration of 0.01 to 2% by weight of the polymerizable material in the composition, although concentrations outside this range may also be used if desired. The ketone is suitably present in a concentration of from 0.1 to 1 and more preferably from 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 suitable for use in the present invention include the peroxides of the formula R 1 -OR 1, wherein the groups R-, which may be the same or different, are hydrogen, an alkyl, aryl, or acyl group wherein no more than one of the 30 R groups is hydrogen. By the term "acylic" is meant a radical of the formula Rg-CO-, wherein Rg is an alkyl, aryl, alkyloxy or aryloxy group. The term alkyl and aryl have the meanings given above for the groups A and also include substituted alkyl and aryl.

Examples of organic peroxides suitable for use in the compositions of the invention include diacetyl peroxide, dibenzoyl peroxide, di-tertiary butyl peroxide, dilauroyl peroxide, tertiary butyl perbenzoate, ditertiary butylcyclohexyl perdicarbonate.

For example, the organic peroxide may be present in the 870256 1 * 10 formulation in an amount in the range of 0.1 to 10% by weight of the polymerizable material in the formulation, although concentrations outside this range may also be used if desired. .

The reactivity of a peroxide is often measured in terms of a temperature at which the half-life is 10 hours, that is, half of the oxygen becomes available at that temperature within 10 hours.

The peroxides in the present compositions preferably have a temperature at which the half-life of 10 hours is less than 150 ° C and even more preferably less than 100 ° C.

The speed at which the preparation according to the invention cures under the influence of visible light can be increased by including in the preparation a reducing agent capable of reducing the ketone when the latter is in an excited state. Suitable reducing agents are described, for example, in German Offenlegungsschrift 2,251,048 and they include organic amines, phosphites and sulfinic acids.

Generally, non-basic reducing agents are preferred because they tend to react less readily with the phosphate ester. Suitable non-basic reducing agents include aldehydes and organotin compounds of the formula (®. <)) NSn (0R] _Q) m 25 wherein n and m are integers of 1, 2 or 3 and n + m = 4, RQ represents an alkyl or alkenyl group with y 1 to 18 carbon atoms and represents R 1 or R 1 CO 2 or has the formula ([R 1 J 1 Sn ^ O.

Mixing of the components can be done by stirring the polymerisable material and any fillers together. It may be useful to first dissolve the catalyst components in the polymerizable material; the polymerizable material can be suitably diluted with, but less preferred, a suitable diluent to improve the dissolution of the catalyst components. When the mixing has taken place, the diluent can be removed if desired, for example by evaporation. Preferably, the present composition is substantially free of any solvent, because its presence may hinder adhesion and lead to toxicity problems.

Since the photosensitive catalyst sensitizes the polymerizable material and monomer to light in the visible range from 400 nm to 500 nm, that portion of the preparation of the present composition in which the photosensitive catalyst is added and the subsequent handling, e.g. container filling, are performed in the substantially complete absence of light 10 in said range. Most suitably, the preparation can be carried out with light outside the said range, for example, the light emitted by electric sodium vapor discharge lamps.

According to a further embodiment of the invention, a curing method is provided which comprises irradiating the preparation according to the invention with visible radiation with a wavelength between 400 nm and 500 nm. The process can be carried out at any suitable temperature, provided that the composition does not crystallize and breaks into splinters, if the temperature is too low or undesirably volatile, the temperature being too high. Preferably the process is carried out at the ambient temperature, i.e. between 15 ° C and 40 ° C.

It is contemplated that a tooth surface will be coated with the subject composition which is then cured under a visible light source, the composition being suitably cured with a portable light source.

A dental preparation according to the invention is preferably packaged in single clay containers (for example, with a capacity of 10 g) to facilitate handling in the treatment and to reduce the risk of accidental curing by, for example, stray light.

For cosmetic purposes, such a dental composition may have the appearance of stained teeth, colored teeth or the natural tooth color, and therefore the present compositions may include small amounts of pigments, opacifiers and the like. The formulation may also contain small amounts of other materials, such as antioxidants and stabilizers, as long as they do not significantly affect curing.

The invention is illustrated by the following examples.

Example I

(a) Preparation of phosphate ester.

Phosphorus oxychloride (127.9 g; 0.83 mol) was mixed with methylene chloride (600 cm3). The mixture was stirred and cooled to 0 ° C. A mixture of hydroxypropylmeth-10 acrylate (120 g; 0.83 mol), pyridine (65.8 g; 0.83 mol) and methylene chloride (400 cm3) was added dropwise to the phosphorus oxide mixture over a period of 45 minutes while keeping the reaction temperature in the range of 0 to 3 ° C. The mixture was stirred for an additional 2 hours in this temperature range. The reaction mixture was then poured into 1 liter of cold water and the methylene chloride layer was separated and washed twice with water. The methylene chloride solution was then mixed with water and the methylene chloride was removed using a rotary evaporator to leave an aqueous phase and a small amount of water-insoluble inorganic material. The aqueous layer was washed twice with methylene chloride then carefully acidified (208 ml hydrochloric acid) with stirring. The aqueous phase was then extracted with ethyl acetate (1 liter) and the aqueous phase was discarded.

The concentration of phosphate ester was then determined and analyzed by acid-base titration methods to find that the ester contained less than 2% by weight of 2-methacryloyloxy-propyl dihydrogen phosphate as an impurity. Thereafter, other ethylenically unsaturated monomer (s) (comonomer or comonomers) were added in the desired amount according to the relative concentration required in the final preparation.

Ethyl acetate was then removed with a rotary evaporator at 65 ° C and under a vacuum of 50 mm Hg.

(b) Preparation of vinyl urethane (VU) was carried out using the method described in Example 1 of European Patent Application 0 059 649.

8702561 - 13 - (c) A number of formulations were prepared with the comonomer concentrations and the compositions listed in Table A. To the monomer mixture, the catalyst components were added as follows: 5 wt%

Camphorquinone 0.73 dimethylaminoethyl-0.49 methacrylate (DMAEM) t-butyl perbenzoate 0.98 10 "Topanol" 0 to 200 ppm calculated on final composition

This addition and subsequent operations carried out with the preparation were performed under the light of a sodium vapor discharge lamp.

Assessment of bond strength to samples of the above formulations were performed according to the procedure described in British Dental Journal 1984, pages 93 to 95, except that the composite recovery material used in conjunction with the adhesive preparation was "Occlusin" (Oeclusin is a trademark of Imperial Chemical Industries PLC). The samples were cured by radiation from a tungsten filament halogen lamp with a matched reflector and a dichroic filter that eliminates ultraviolet radiation; the intensity _2 was 1000 Wm and the curing time was 30 seconds.

"Topanol" is a trademark of Imperial Chemical Industries PLC and "Topanol" 0 is 2,6-ditertiary-butyl-4-methylphenol.

30 87 0 256 1 r - 14 - *

Table A

Phosphate ester Wt% Comonomer Adhesion strength phosphate (MPa) _ ester Internal External (Deep) (Upper surface) 0 * RO - P - OH 10 (i) TEGDM 8.0 ± 3.6 18.1 ± 6.4 I 10 ** (ii) VUTEGDM A? +? R IA 7 OH (50) (50) 6.3 ± 3.8 14.2 ± 6.2 relative wt, amount 5 80 7 0 0 0

«II II

RO-P-OH + RO-P-OR + RO-P-OR 35 (iii) TEGDM 9.8 ± 4.6 12.1 ± 3.1

| I I 50 ** (iv) VUTEGDM fi +, «9+, R

OH OH OR (50) (50) 8.8-4.3 13.2-5.8 relative weight 24 48 4 0 0 0

II II II

R0-P-C1 + R0-P-0R + R0-P-0R 20 ** (v) VUTEGDM 3.4 ± 1.5 8.1 ± 2.0 I I I (50) (50)

Cl Cl 0R

(vi) bisGMA 3.9 ± 2.0 10.2 ± 1.4 to 25% +

Scotchbond (in TEGDM

(3M) ethanol) 0pm .: CH, 0CH „CH„ O CH_ I 3 II I 3 I 3 II I 3 R: CH2 = C - C - 0CH2CH -, CH2 - C - C - 0 - CHCH2- * According to the invention ** adhesive applied as a 20 wt% solution in ethanol TEGDM triethylene glycol dimethacrylate.

8702561 5 - 15 - 5

Example II

An adhesive preparation was prepared as described in Example I, having the following composition: 5

Wt. parts

Phosphate ester (Example Ia) 9.78 TEGDM 90.22

Camphorquinone 0.73 10 Dibutyltin dilaurate 0.49 t-butyl perbenzoate 0.98 "Topanol" 0 to 200 ppm

A sample of the above formulation 15 was cured and evaluated as described in Example I.

and was found to have a bond strength similar to that in Table A (i).

Example III

20

A series of adhesive compositions were prepared as described in Example I, but using a series of tin compounds in place of the DMAEM.

Samples of the formulations were evaluated for their cure time using the oscillating rheometer technique described above.

Parts by weight

Phosphate ester (Example Ia) 15 30 TEGDM 85

Camphorquinone 0.75

Tin connection 0.5 35 8702 561 r - 16 -

Tin joint Curing time _ (seconds)

None * 126 dibutyltin diacetate 96 5 dibutyltin dilaurate 90 dioctyltin diacetate 75 tributyltin acetate 30 tributyltin methacrylate 43 bis (tributyltin oxide) 30 10 tributyltin methoxide 24 * same result as obtained with 0.5% DMAEM. 15 8702561

Claims (10)

A one component liquid adhesive composition which can be cured by visible light and has a viscosity of less than 25 centipoises at 25 ° C, comprising a) 2 to 20 parts by weight of at least one substantially pure phosphate ester of the formula CH 2 CCR 3 ) .C0.0.R2.0P (0) (OH) 2 where R ^ represents a hydrogen atom or a methyl group and R2 represents -C ^ -C ^ j -C1 ^ -CHCCH ^) - or -CH (CH3) - CH2, and b) 98 to 80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphate ester, and an effective amount of a catalyst activated by visible light. The composition of claim 1, wherein is a methyl group. The composition according to claim 1 or 2, wherein R 2 is a propylene group. A composition according to any preceding claim wherein the visible light activated catalyst comprises an α-diketone. The formulation of claim 4 wherein the diketone is camphorquinone. The formulation of any preceding claim wherein the visible light activated catalyst comprises an organotin compound. The formulation of any preceding claim, wherein the visible light activated catalyst comprises an organic peroxide. Preparation according to any one of claims 1 to 7, wherein the impurity content in the phosphate ester is less than 2% by weight. The composition according to any one of claims 1 to 8, wherein the concentration of the phosphate ester is 5% by weight or more. 10. Use of an adhesive preparation according to any one of the preceding claims, comprising coating a surface of a tooth with the preparation and irradiating the preparation at ambient temperature with visible light of a wavelength. in the range from 400 nm to 500 nm. -o-o-o-o-o- 8702561 f ^ V / 9hj OH \ CHj / I I 6 - \ i ch 2 = C-co. o — CH2 —CH —CHZ— o - \ y - cvw / I ACCA —cC- II II II II OO 0 0 2 3 Ph-C - C —— ^ - Ph li II 0. i * Imperial Chemical Industries plc, London, Great Britain 8702 56 1