SE470063B - One component, visible light curable liquid adhesive composition comprising a phosphate ester - Google Patents

Description

Organic phosphate esters. It is therefore highly desirable that the active adhesive component has a low concentration in the adhesive composition and that component therefore does not have to have high adhesive properties. Compositions should have a low viscosity so that it flows smoothly over the surface to be glued to.

EP 0074708 A1 discusses a number of patent publications. in which various ethylenically unsaturated phosphorus esters are described as adhesives.

Said patent specification has specific phosphate esters based on a long-chain alkyl ester of acrylic and methacrylic acids and is stated to have improved adhesive properties in the dental context. The patent states that 2-methacryloxyethyl dihydrogen phosphate is a relatively weak adhesive component and causes blistering in a lacquer film. EP 0115948 A1 describes the use of organic pyrophosphate esters as polymerizable adhesive components. EP 0058583 and 013218 A1 describe the use of halophosphosic acid esters as polymerizable monomers in a tooth glue; these esters contain at least one ethylenically unsaturated functional group and a chlorine or bromine tone attached directly to the phosphorus atom.

US-A-4044044 describes the use of phosphate esters of hydroxyacrylates as components in anaerobic adhesive compositions.

These compositions are said to remain in the liquid state as long as they are in contact with air while being said to cure rapidly by polymerization with the exclusion of air. Such adhesive compositions are useful as materials to prevent tooth loss especially at high pressure.

It has now been found that the adhesive properties associated with polymerizable esters of phosphoric acid depend not only on the degree of contamination in the specific ester but also on the presence of a small amount of a related fine-grained filler.

According to the invention, a one-component is provided. with visible light curable liquid adhesive composition. which comprises 10-20 parts by weight of at least one substantially pure phosphate ester of the formula CH 2 -C (R 1 COCO.R 2 OP (O) (OH) 3 wherein R 1 is a hydrogen atom or a methyl group and R is -CH 2 -CH 2 -, -CH 2 -CH (CH 3) - or -CH (CH 3) -CH 2 - and b) 98-80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphate ester and c) 1-9% by weight, calculated on a + b, of at least one inorganic filler with a particle size of less than 0.1 μm and an effective amount of a catalyst activated by visible light.

The phosphoric ester component of the compositions in question is preferably 2-methacryloyloxypropyl dihydrogen phosphate. The phosphate esters used in the compositions of the invention can be prepared by, for example, reacting 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 chlorophosphorus compounds. The dihydrogen phosphoric acid ester is then purified by a series of washing and extraction steps so that the ester is substantially pure. i.e. free from other esters of phosphoric acid so that such a level of contamination is less than 5% by weight. preferably less than 2% by weight.

The adhesive compositions of the invention contain at least one ethylenically unsaturated monomer copolymerizable with the phosphate ester.

The most commonly used monomers include those of the (co) acrylate, vinyl urethane and styrene types, and vinyl acetate.

Other monomers such as (meth) acrylamides. vinyl ethers, fumarates. however, maleates, vinyl ketones, vinyl nitriles, vinyl pyridines and vinyl naphthenes can also be used either alone or in combination provided that the viscosity parameter of the composition is met. The concentration of the phosphate ester in the adhesive composition is preferably 5 parts by weight or more and preferably at most 15 parts by weight.

Vinyl esters are suitable for use in the process according to the invention. The invention includes, for example, vinyl acetate and esters of acrylic acid of the formula CH 2 = CH-COOR 3, where R 3 is an alkyl, aryl. alkaryl aralkyls or cycloalkyl group For example, R 3 may be an alkyl group having 1-20, preferably 1-10 carbon atoms.

Specific vinyl esters which may be mentioned include, for example, methyl acrylate, ethyl acrylate. n- and isopropyl acrylates and n-, iso- and t-butyl acrylates.

Other suitable vinyl esters include, for example, esters of the formula cH2 = 'c (R4) cooR3 where R4 is methyl. In the ester of the formula cH2 = c (R4) coon3, R? and R 4 be the same or different.

Particular vinyl esters which may be mentioned include, for example, methyl methacrylate, ethyl methacrylate. n- and isopropyl methacrylate and n-, iso- and t-butyl methacrylic vinyl esters such as n-hexyl-. cyclohexyl and tetrahydrofurfuryl acrylates and methacrylates.

The monomers should show low toxicity. Suitable styrene-type aromatic vinyl compounds include, for example, styrene and derivatives thereof. eg alpha-alkyl derivatives of styrene. eg alpha-methylstyrene and vinyltoluene.

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

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

Polyfunctional monomers are also suitable as polymerization materials. i.e. monomers containing two or more vinyl groups. Suitable monomers include, for example, glycol dimethacrylate, diallyl phthalate and triallyl cyanurate.

The ethylenically unsaturated material may include at least one ethylenically unsaturated polymer suitably in combination with at least one ethylenically unsaturated monomer.

The composition is preferably free of volatile solvent.

Such polymerizable materials are preferably liquid ethylenically unsaturated materials such as vinyl urethane. for example those described in GB Patents 1352063. 1465097 and 1498421 and DE Offenlegungsschrift 2419887 or the reaction product of a diol such as glycol but in particular a bisphenol with a glycidyl alkacrylate such as those described e.g. in US-A-3066112 and 4131729 (contents in these publications is introduced here as a reference).

A preferred reaction product of a glycidyl alkacrylate and a diol has the formula: m 3 on CH 2: C-CO. O-CH 2 -CH-CH 2 Preferred vinyl urethanes described in said GP patents and DE 0fenlegungsschrift are the reaction product of a urethane prepolymer and an ester of acrylic or methacrylic acid with a hydroxyalkanol having at least 2 carbon atoms, the urethane prepolymer being the reaction product. a diisosyanate of the formula OCN-R5-NCO and a diol of the formula HO-R6-OH wherein R5 is a divalent hydrocarbon group and R6 is the remainder of a condensate of -IN * <1 in CDCl3 xl an alkylene oxide having 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 those described in GB-A-1401805, 1428672 and 1430303 (the contents of which are incorporated herein by reference).

The tooth compositions of the invention are cured by irradiating the composition with visible radiation. preferably those with a wavelength in the range between 400 mn and 500 mn. In order for the curing of the compositions to be achieved in this range, the compositions contain a catalyst which is activated by visible light. Such a catalyst preferably contains at least one ketone wad of fluorenone and diketone and at least one organic peroxide.

Ketones suitable for use in the composition of the invention also exhibit some photosensitive catalytic activity per se without the presence of organic peroxide. Such activity of the ketone is enhanced by the addition of a reducing agent as described in DE Offenlegungsschrift 2251048. The ketones in question are thus selected from fluorenone and α-diketones and and derivatives thereof as in admixture with an approximately equal amount of organic amine capable of reducing the ketone when the latter is in an excited state but in the absence of organic peroxide catalyzes the curing of an ethylenically unsaturated material. Evidence of curing can be conveniently read by examining the change in viscosity of a mixture of the ethylenically unsaturated material containing the ketone and organic amine each in an amount of 1% by weight based on the ethylenically unsaturated material using an oscillating rheometer, the sample thicknesses being 2 mm while the mixture is irradiated with light having a wavelength in the range 400-500 mu. Such an examination may be carried out using the method described in British Standard 5199: 1975. paragraph š.4 provided that measures are taken to direct visible light towards the mixture f: 10 15 20 25 30 35 470 065. Preferably, the ketone has a cure time of less than 15 minutes at a radiation level of 1000 w / m 2 measured at 470 mu. bandwidth for 8 mn. for example using a Hacam Radiometer (Macam Photometrics 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 wherein the groups A may be further linked with a divalent bond or with a divalent hydrocarbyl or substituted hydrocarbyl groups or wherein the groups A together can form a condensed aromatic ring system. Preferably, the groups A are the same.

The groups Ä can be älifätí fi ka or ärOlllätíßkä. IIIOIII rämê fl -for the term aliphatic include cycloaliphatic groups and aliphatic groups bearing aromatic substituents. i.e. aralkyl groups. Also within the scope of the term aromatic group are included groups bearing alkyl substituents. i.e. alkaryl groups. The term aromatic groups includes heterocyclic groups.

The aromatic group may be an aromatic benzenoid group, eg the phenyl group, or a cyclic non-benzenoid group which is recognized as possessing the properties of an aromatic benzenoid group.

Groups A can. especially when they are aromatic. carry substituent groups other than hydrocarbyl. eg halogen or alkoxy. Substituents other than hydrocarbyl may result in inhibited polymerization of ethylenically unsaturated materials and if the alpha-diketone contains such substituents, it is preferably not present in the photopolymerizable composition at such a concentration that it results in significant There is about an inhibition of the polymerization of the ethylenically unsaturated material in the composition.

Groups A can be further interconnected via a direct bond or via a divalent group. for example a divalent hydrocarbyl group. i.e. in addition to the bond via the group Groups A may further be interconnected to form a cyclic ring system. For example, when groups A are aromatic, the α-diketone may have the formula (Y) m Ph.- E-E - Ph O O in which Ph is a phenylene group. Y is> CH 2. or a derivative thereof wherein one or both hydrogen atoms are replaced by a hydrocarbyl group and m is 0. 1 or 2. Preferably the group Y is attached to the aromatic groups in the ortho position of the group.

Groups A can together form a fused aromatic ring system.

Usually α-diketones have the ability to be excited by radiation within the visible light range. i.e. of light with a wavelength higher than 400 mu. eg in the wavelength range 400-500 mn. For the present invention, the α-diketone should have a low volatility in order to keep the odor and concentration variation down as much as possible. Suitable α-diketones include benzyl. in which both groups A are phenyl, α-diketones in which both groups A are fused aromatics. for example α-naphthyl and β-naphthyl and α-diketones in which the 4) groups A are alkaryl groups, eg β-tolyl. An example of a suitable α-diketone in which groups A are aromatic non-benzenoids is furil. for example 2: 2'-furil. Derivatives of the α-diketone in which groups A carry non-hydrocarbyl groups such as p.p'-dialkoxybenzyl, eg p, p'-dimethoxybenzyl or P.p'-dihalobenzil. eg p.p'-dichlorobenzyl or p-nitrobenzyl may be included.

The groups A can be linked together by a direct bond or by a divalent hydrocarbyl group to form a cyclic ring system. For example, when groups A are aliphatic, the α-diketone may be camphorquinone.

An example of an α-diketone of formula I is phenanthraquinone in which the aromatic groups A are linked by a direct bond ortho to the group _ C..C._ H U O 0 Suitable derivatives include 2-bromo-. 2-nitro-. 4-nitro, 3-chloro- and 2,7-dinitro-1-methyl-7-isopropylphenanthraquinone. the α-diketone may be acenaphthenic quinone in which the groups A together form a fused aromatic ring system.

The ketone may also be fluorenone and derivatives thereof such as lower alkyl (C 1-6). halo, nitro. carboxylic acid and esters thereof. especially in 2- and 4-positions.

For example, the ketone may be present in the composition in a concentration between 0.01 and 2% by weight of the polymerizable material in the composition, although concentrations outside this range may be used if desired. Suitably the ketone is present in a concentration of 0.1-1% by weight and most preferably in a concentration of 0.5% by weight of the ethylenically unsaturated material in the composition. The ketone should be soluble in the polymerizable material and the above concentrations refer to solution concentrations.

The organic peroxides suitable for use in the composition in question include those of the formula R 7 - O - O - R 7 in which the groups R 7. which may be the same or different, are hydrogen, alkyl-. aryl or acyl groups, at most one of the groups R being hydrogen. The term acyl means that the group has the formula Ra - co - In which RB is an alkyl-. aryl-. alkoxy or aryloxy group.

The term alkyl and aryl have the above definition for groups A and include substituted alkyl and aryl.

Examples of organic peroxide suitable for use in the composition of the invention include diacetyl peroxide. dibenzoyl peroxide. di-t-butyl peroxide, dilauroyl peroxide. t-butyl perbenzoate, di-t-butylcyclohexyl perdicarbonate. For example, the organic peroxide may be present in the composition in an amount in the range of 0.1-10% by weight of the polymerizable material in the composition, although a concentration outside this range may be used if desired.

The reactivity of a peroxide is often measured in terms of a 10 hour half-life temperature, i.e. within 10 hours at which temperature half of the oxygen has been made available. The peroxides in the compositions preferably have 10 hour half-life temperatures lower than 150 ° C, more preferably lower than 100 ° C. The rate at which the composition of the invention cures under the influence of visible light can be accelerated by incorporation into the composition of a reducing agent in a concentration of 0.1-10% by weight of the polymerizable material, which is capable of reducing the ketone when the latter is in an excited state Suitable reducing agents are described, for example, in DE Offenlegungsschrift 2251048 and include organic amines, phosphites and sulfinic acids.

In general, non-basic reducing agents are preferred because they are less likely to react with the phosphate ester. Suitable non-basic reducing agents include aldehydes and organotin compounds of the formula Sn (ORI) (R) II m in which n and m are integers having the value 1,2 or 3 and n + m = 4. 9 n.

R is an alkyl or alkenyl group containing 1-18 carbon atoms and R 10 is R 9 or R 9 CO- or has the formula ([R 9] 3sn) 20 The filler is present in an amount of 1-9% by weight of the composition, preferably in an amount of 4-6% by weight. The filler in any form of silica including finely divided forms of crystalline silica such as sand but is preferably a colloidal form such as fumed, shaped or precipitated silica.

The mixing of the components can be performed by mixing the polymerizable material and the filler. It may be useful to dissolve the catalyst components first in the polymerizable material; the polymerizable material can be smoothly but less conveniently diluted with a suitable diluent to improve the solubility of the catalyst components. Once the mixing is complete, the diluent can be removed if desired. eg by evaporation. The composition is preferably substantially free of solvent as its presence can interfere with the adhesion and give rise to toxicity problems. Since the photosensitive catalyst makes the polymerizable material and the monomer sensitive to light in the range of 400-500 μm, it should be that of the preparation of the composition whereby the photosensitive catalyst is added and subsequent processing. eg filling containers, is carried out in the substantial absence of light in this area. The preparation can most conveniently be carried out using light outside this range. discharge lamps based on gaseous sodium. For example, under the light emitted by electric. According to a further embodiment of the invention, a curing process is provided which consists in irradiating the composition according to the invention with visible light with a wavelength of between 400 and 500 μm. The process can be carried out at any suitable temperature provided that the composition does not crystallize and fragment, the temperature being too low. or volatilize to an excessive extent. whereby the temperature is too high. Preferably, the process is carried out at room temperature. i.e. between 15 and 40 ° C. The intention is that a tooth surface should be coated with the composition according to the invention and then cured under the influence of visible light, and suitably the composition is cured with a portable light source. However, it is preferred that the tooth surface be treated with primer before it is coated in said manner and a preferred primer is a bisbiguanide. polybiguanide or long chain quaternary salt of the type described in GB-A-8810412.

A dental composition according to the invention is preferably packaged in a single small container (eg receiving 10 g) to facilitate handling during the procedure and reduce the risk of undesired curing with, for example, stray lice. rd For cosmetic purposes, such a dentifrice composition may have a gloss. colored or natural tooth appearance and consequently the composition in question may include small amounts of pigments. opalescents and the like. The composition may also contain small amounts of other materials such as antioxidants and stabilizers provided that they do not significantly affect curing. 10 15 20 25 30 35 470 063 _13 The invention is illustrated with reference to the following examples.

Example 1 (a) Preparation of phosphate ester.

Phosphorus oxychloride (127.9 g, 0.83 mol) was mixed with methylene chloride (600 cm 3). The mixture was stirred and cooled to 0 ° C. A mixture of hydroxypropyl methacrylate (120g, 0.83 mol). pyridine (65.8 g, 0.83 mol) and methylene chloride (400 cm 3) were added dropwise to the phosphorus oxychloride mixture over a period of 45 minutes while maintaining the reaction temperature in the range 0-3 ° C.

The mixture was stirred for a further 2 hours within said temperature range. The reaction mixture was then poured into 1 L of cold water and the methylene chloride layer was separated, washed twice with water. The methylene chloride solution was then mixed with water and the methylene chloride was removed using a rotary evaporator leaving an aqueous phase and some water-insoluble organic material. The aqueous layer was washed twice with methylene chloride and then carefully acidified (hydrochloric acid 208 cm 3) with stirring and the aqueous phase was then extracted using ethyl acetate (1 L) and the aqueous phase was discarded. The concentration of phosphate ester was then estimated and analyzed by acid-base titration methods and found to contain ester impurity_ less than 2% by weight of 2-methacryl-oyloxypropyl dihydrogen phosphate. Triethylene glycol dimethacrylate (TEGDM) was then added to give a 90:10 mixture of TEGDM: phosphate. Ethyl acetate was then removed by rotary evaporation at 65 ° C and under a vacuum of 50 mm Hg. (b) A number of formulations were prepared having the filler concentration and composition given in Table 1. To the imonomer mixture were added the following catalyst components: 10 V15 20 25 30 470 '063 14% by weight Camphorquinone 0.73 Dibutyltin dilaurate 0.49 "Topanol" to 200 ppm of the final composition "Aerosil" A130 varying This addition and subsequent processing of the composition was carried out under a gaseous sodium discharge lamp.

The evaluation of the adhesion strength of samples of the above composition was performed using the method described in the British Dental Journal 1984. pages 93-95 except that the composite material used in combination with the adhesive composition was "Occlusin ®" (Imperial Chemical Industries PLC). .

The dentin surface was coated with a solution of "Vantoci1" (0.1% by weight in water) followed by drying with an air blower before the adhesive formulation was applied. "Vantocil" is a polybiguanide of the formula [(CH2) 6-NH.C ( : NH) .NH.C (: NH) NH] n where n is 4-7.

"Vantocil®" is a trademark of Imperial Chemical Industries PLC. The samples were cured by irradiation with tungsten halogen lamp with tinted reflector and dichromatic filter which eliminated 2 ultraviolet radiation and the intensity was 100 Nm 'and the curing time was 30 s.

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

"Aerosil ®" is a trademark of Degussa AG; "Aerosil ® A130" is a hydrophilic grade of fine dispersed silica with an average particle size of 0.02 μm. 10 15 25 30 35 15 Table 1% Filler 7.5 10 Joint strength (MPa) 7.0 13.0 11.0 7.0 4 7 Ü. Û 5 The above results are presented in the attached drawing figure.

Example 2 Similar values of joint strength were obtained using an adhesive with the following composition: Phosphate ester (according to example) Vinyl urethane resin * TEGDM Camphorquinone Dibutyltin dilaurate "Aerosil" A130 * According to example 1 in EP 59649 Vinyl urethane resin and the phosphate ester TEG the quantity of ïEGDM thus added was included in the total TEGDM content.

Claims (10)

470,063 16 Patent claims One-component, visibly curable, liquid adhesive composition, characterized in that it consists essentially of (a) 2-20 parts by weight of at least one substantially pure phosphate ester of the formula cH2 = c (a1) .co.o R 2 .OP (o) (oH) 2 in the 1xene R 1 is a hydrogen atom or a methyl group and R 2 is -CH 2 -CH 2 -. -CH 2 -CH (CH 3) - or -CH (CH 3) -CH 2 - and (b) 98-80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphate ester and (c) 1-9% by weight. calculated on a + b. of a fine-grained inorganic filler and an effective amount of a visible light-activated catalyst. Composition according to Claim 1, characterized in that the phosphate ester has the formula cn2 = c (cn2) .co.o.R2.oP (o) (on) 2 in which R propylene group. 2 is an iso- Composition according to Claim 1 or 2, characterized in that the concentration of the phosphate ester is 5-15 parts by weight. Composition according to any one of claims 1-3. It is known that the ethylenically unsaturated monomer contains a glycol dimethacrylate. 5. A composition according to claim 4, characterized in that the monomer also includes a vinyl urethane. Composition according to any one of claims 1-5. know that the amount of filler present is between 4 and 6% by weight. Composition according to any one of claims 1-6. k ä n n e - t'e c k n a d that the filler is colloidal Eiseldioxide. d! f ~ 470 063 17 Composition according to any one of claims 1-7. It is known that the catalyst activated by visible light comprises camphorquinone and a reducing agent. Composition according to Claim 8, characterized in that the reducing agent is an organic tin compound of the formula (R °) nsn (oR1 °) m in which n and m are integers with the value 1, 2 or 3 and n + m = 4. R 9 is an alkyl or alkenyl group containing 1-18 carbon atoms and R 10 is R 9 or R 9 CO-. 10. A composition according to claim 8, characterized in that the reducing agent is an organic tin compound of the formula ([R913sn) 2o in which R9 is an alkyl or alkenyl group containing 1-18 carbon atoms.