SE467040B - INCOMPONENT BINDING COMPOSITION INCLUDING A SIGNIFICANT PURE PHOSPHATESTER - 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

Practicing dentist and almost all are based on organic phosphate esters. It is therefore highly desirable that the active binder component have a low concentration in the binder composition and therefore the component must have strong binder properties. The composition should have a low viscosity so that it flows smoothly over the surface to be bonded.

EP 0 074 708 discusses a large number of patent publications. in which various ethylenically unsaturated phosphoric acid esters are described as binders. In the said publication, special phosphate esters on the basis of an alkyl ester with a long carbon chain of acrylic and methacrylic acids are subject to protection and are stated to have improved binder properties in dental contexts. The publication states that 2-methacryloyloxyethyl dihydrogen phosphate is a relatively poor binder component and causes blistering in a paint film. EP 0 115 948 describes the use of organic pyrophosphate esters as polymerizable pharmaceutical components. EP 0 058 483 and 0 132 318 describe the use of halophosphoric acid esters as polymerizable monomers in a dentifrice, these esters containing at least one ethylenically unsaturated functional group and a chlorine or bromine atom directly bonded to the phosphorus atom.

US-A-4,044,044 discloses the use of phosphate esters of hydroxyacrylates as components in anaerobic binder compositions. Such compositions are said to remain in a liquid state as long as they remain in contact with air while being said to cure rapidly by polymerization with the exclusion of air. These binder compositions are useful as anti-slip materials, especially at high pressure.

It has now been found that the binder properties associated with polymerizable esters of phosphoric acid depend on the degree of contamination in the specific ester. Thus, if a dihydrogen phosphate ester is substantially free of phosphoric acid, the non-hydrogen ester and the fully esterified ester. so the resulting binder composition is surprisingly effective as a binder in an aqueous environment. The present invention provides storage stable binder compositions which are rapidly curable in the presence of air.

According to the invention there is provided a one component, visually curable, liquid binder composition having a viscosity of less than 25 cP at 25 ° C, which comprises (a) 2-20 parts by weight of at least one substantially pure phosphate ester of the formula CH 2 = C (R 1). CO.O.R2.0P (O) (OH) 2, in which R1 is a hydrogen atom or a methyl group and R2 is -CH2-CH2-, -CH2-CH (CH3) - or -CH (CH3) - CH2 and (b) 98-80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphate ester and an effective amount of a visible light activated catalyst.

The phosphoric acid ester component of the compositions is preferably 2-methacryloyloxypropyl dihydrogen phosphate. The phosphate esters used in the compositions according to the invention can be prepared by e.g. 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 residual 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 this level of contamination is less than 5% by weight, preferably less than 2% by weight.

The binder compositions of the invention contain at least one ethylenically unsaturated monomer 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 the monomer. A large amount of monomer (s) is suitable for the compositions provided that the viscosity of the resulting composition is less than 25 cP at 25 ° C. The most commonly used monomers are those of the (meth) acrylate, vinyl urethane and styrene type and vinyl acetate. Other monomers, such as (meth) acrylamides, vinyl ethers, fumarates. however, maleates, vinyl ketones, vinyl nitriles, vinyl pyridines and vinyl naphthalenes can also be used either singly or in combination provided that the viscosity parameter of the composition is met. The concentration of the phosphate ester in the binder composition is preferably 5% by weight or higher and preferably not higher than 15% by weight.

Vinyl esters suitable for use in the process of the invention include e.g. vinyl acetate and esters of acrylic acid of the formula CH 2 = CH-COOR 3, wherein R 3 is an alkyl, aryl, alkaryl, aralkyl or cycloalkyl group. R3 can e.g. be an alkyl group of 1-20. preferably 1-10 carbon atoms. Special vinyl esters that can be mentioned are e.g. methyl acrylate, ethyl acrylate, n- and isopropyl acrylates and n-, iso- and t-butyl acrylates.

Other suitable vinyl esters include e.g. esters of the formula CH 2 = C (R 4) CO 3 R 3 where RA is methyl. In the ester of the formula cnz = cuz4) coon3, R3 and R4 may be the same or different.

Special vinyl esters that can be mentioned are e.g. methyl methacrylate, ethyl methacrylate. n- and isopropyl methacrylate and n-, iso- and t-butyl methacrylate. vinyl esters such as n-hexyl, cyclohexyl and tetrahydrofurfuryl acrylates and methacrylates. The monomers should have low toxicity. Suitable styrene-type aromatic vinyl compounds include e.g. styrene and derivatives thereof. for example u-alkyl derivatives of styrene, e.g. n-methylstyrene, and vinyl toluene.

Suitable vinyl nitriles include e.g. acrylonitrile and derivatives thereof. for example netacrylonitrile. 10 15 20 25 30 35 467 040 Other suitable. ethylenically unsaturated monomers include vinyl pyrrolidone and hydroxyalkyl acrylates and methacrylates, e.g. hydroxyethyl acrylate. hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

Multifunctional monomers are also suitable as polymerization materials, i.e. monomers containing two or more vinyl groups. Suitable monomers include e.g. glycol dimethacrylate. diallyl phthalate and triallyl cyanuarate.

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

The composition of the invention is preferably free of volatile solvent. However, if a solvent is included, the following polymerizable materials may also be present provided that the viscosity of the composition is lower than 25 cP at 25 ° C.

Such polymerizable materials are preferably liquid, ethylenically unsaturated materials such as vinyl urethane, e.g. they are described in GB 1 352 063. 1 465 097 and 1 498 421 and DE 0 419 887 or the reaction product of a diol. such as glycol 1 in particular a bisphenol, with a glycidyl alkacrylate, such as those described e.g. in US-A-3,066,112 and 4,131,729 (the contents of these publications are incorporated herein by reference).

A preferred reaction product of a glycyl dyl alkacrylate and a diol has the formula: CH 3 OH CH 3 9 caz-c-cmo-cuz-cn-caz 10 15 20 25 30 35 467 040 ° Preferred vinyl urethanes described in said GB patents and DE patent publication 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 of a diisocyanate of the formula OCN-R5-NCO and a diol of the formula H0-R6-OH. wherein R 5 is a divalent hydrocarbyl group and R 6 is the remainder 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 those described in GB 1,401,805, 1,428,672 and 1,430,303 (the contents of which are incorporated herein by reference).

The dental compositions according to the invention are cured by irradiating the composition with visible radiation, preferably those with a wavelength in the range 400-500 mp. In order for 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 selected from 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 of the kind described in DE 2 251 048. Thus, the ketones in question are selected from fluorenone and α-diketones and derivatives thereof, which in admixture with a similar amount of organic amine, sol is in able to reduce this ketone when the latter is present in an excited state but in the absence of organic peroxide catalyzes curing of an ethylenically unsaturated material.

Signs of curing can be conveniently detected 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 ethylenically unsaturated material with using an oscillating rheometer with sample thicknesses of 2 mm while the mixture is irradiated with light having a wavelength in the range 400-500 mp. Such an examination may be carried out using the method described in British Standard 5l99: l975, § 6.4, provided that measures are taken to direct visible light towards the mixture.

Preferably, the ketone has a curing time of less than 15 minutes at an irradiation level of 1000 W / m2 measured at 470 mn, bandwidth ¿8 mn, e.g. using a Hacam radiometer (Hacam Photometrics Ltd., Edinburgh, Scotland).

Diketones of the formula: A - C - C - A 0 0 in which the groups A, which may be the same or different, are hydrocarbyl groups or substituted hydrocarbyl groups and the groups A may further be linked via a direct bond or through a divalent hydrocarbyl group or substituted hydrocarbyl group or where the groups A together may form a fused aromatic ring system. Preferably, the groups A are the same.

Groups A may be aliphatic or aromatic. The term aliphatic includes cycloaliphatic groups and aliphatic groups, which bear aromatic substituents. i.e. ar-alkyl groups. Likewise, within the term aromatic group are groups bearing alkyl substituents. i.e. alkaryl groups. Within the framework of the term aromatic groups, heterocyclic groups are included.

The aromatic group may be a benzenoid aromatic group, e.g. phenyl group, or a non-benzenoid cyclic group. which is recognized in the art as possessing the properties of a benzenoid aromatic group.

Groups A can. especially when aromatic, bear substituent groups other than hydrocarbyl. for example halogen or alkoxy. Substituents other than hydrocarbyl may result in an inhibition of 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 results in significant inhibition of polymerization of the ethylenically unsaturated material in the composition.

The groups A may further be joined 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 _ C _ C _ ö ö, the groups A may be further interconnected to form a cyclic ring system. When e.g. the groups A are aromatic, the α-diketone may have the formula (v), / in Ph - C'-C-'Ph H N 0 0 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 _ C _ O C10. form a condensed aromatic ring system. α-diketones generally have the ability to be excited by irradiation within the visible light spectrum. i.e. with light having a wavelength greater than 400 mn. for example within the wavelength range 400-500 mn. For the present invention, α-diketone should have a low volatility to reduce odor and concentration variations. Suitable u-diketones include benzyl, wherein both groups A are phenyl, u-diketones in which both groups A are fused aromatic, e.g. α-naphthyl and β-naphthyl, and β-diketones in which the groups A are alkaryl groups, e.g. p-tolil. As an example of a suitable α-diketone, in which the groups A are non-benzenoid aromatic groups, furil may be mentioned, e.g. 2: 2'-furil. Derivatives of the u-diketone, in which groups A carry non-hydrocarbyl groups, such as e.g. p, p'-dialkoxybenzyl, e.g. p, p'-dimethoxybenzyl or p, p'-dihalobenzil, e.g. p, p'-dichlorobenzyl or p-nitrobenzyl, may be included.

The groups A may be linked together by a direct bond or via a divalent hydrocarbyl group to form a cyclic ring system. NAr e.g. 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 joined via a direct ortho bond to the group C 0 C10 Suitable derivatives include 2-bromo-, 2-nitro-, 4-nitro-, 3- chloro-, 2,7-dinitro- and 1-methyl-7-isopropylphenanthraquinone. The u-diketone may be an acenaphthene quinone, in which the groups A together form a fused aromatic ring system.

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

The ketone can e.g. be present in the composition in a concentration in the range of 0.01-2% by weight of the polymerizable material in the composition, although concentrations outside this range may be used if desired. The ketone is suitably present in a concentration of 0.1-1% by weight and most preferably 0.5-1% 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 concentration.

The organic peroxides suitable for use in the composition include those of the formula R 7 - O - O - R 7 where the groups R 7 may be the same or different and are hydrogen, alkyl, aryl or acyl groups, not more than one of the groups R 7 is hydrogen. The term acyl denotes the formula RB - co - in which R8 is an alkyl, aryl, alkoxy or aryloxy group.

The term alkyl and aryl have the above definitions 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.

The organic peroxide can e.g. 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 this temperature, half of the oxygen has been made available. The peroxides in the compositions in question preferably have 10 hour half-life temperatures lower than 150 ° C, most preferably lower than 100 ° C. The rate at which the composition of the invention cures under the influence of visible light can be increased by introducing into the composition a reducing agent capable of reducing the ketone when the latter is in the excited state. Suitable reducing agents are described e.g. in DE 2 251 048 and includes 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 formula: 9 (R in ° Sn (ORI) m in which n and m are integers having 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 or R .CO- or has the formula 9 ([R] 3Sn) Mixing of the components can be performed by mixing together the polymerizable material and any filler. first dissolving the catalyst components in the polymerizable material, the polymerizable material suitably but not preferably being diluted with a suitable diluent to improve the dissolution of the catalyst components.Once the mixing has been carried out, the diluent may be removed if desired, e.g. The composition is preferably substantially free of solvents as its presence may interfere with the binding ability and may give rise to toxicity problems.

Since the photosensitive catalyst makes the polymerizable material and monomers sensitive to light in the visible range between 400 mu and 500 μm, the part of the preparation of the composition is carried out, where photosensitive catalyst is added and subsequent manipulation, e.g. filling of containers, in the substantial absence of light within this range. The preparation is preferably carried out using light outside this range. for example under light emitted by electric discharge lamps containing sodium gas.

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

Typically, a tooth surface is coated with the composition in question and then cured under a visible light source. suitably the composition is cured from a portable light source.

A dental composition according to the invention is preferably packaged in individual small containers (holding eg 10 g) to facilitate handling in connection with procedures and reduce the risk of accidental curing by e.g. stray light.

For cosmetic purposes, such a dental composition may be colored or have the appearance of natural teeth and the composition may therefore contain small quantities 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 substantially affect the cure.

The invention is illustrated by reference to the following examples.

Example 1 (a) Preparation of phosphate ester Phosphorus oxychloride (127.9 g, 0.83 mol) was mixed with methylene xiona (soo ef). The mixture is stirred and cooled to C111 ° C.

A mixture of hydroxypropyl methacrylate (120 g, 0.83 mol), pyrene (e5.ag, o, .a3 moi) and methylene chloride (400 cn3) was added dropwise to the phosphorus oxychloride mixture over a period of 45 hours. minutes while keeping the reaction temperature in the range of 0-3 ° C. The mixture was stirred for a further two 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 a small amount of water-insoluble inorganic material. The aqueous layer was washed twice with methylene chloride and then carefully acidified (hydrochloric acid 208 cm 3) with stirring. The aqueous phase was then extracted with ethyl acetate (1 L) and the aqueous phase was discarded. The concentration of phosphate ester was then determined and analyzed by acid-base titration methods and found to contain ester impurities less than 2% by weight of 2-methacryloyloxy-propyl dihydrogen phosphate. Another ethylenically unsaturated monomer (comonomer) was then added as desired in accordance with the relative concentrations required in the final composition. Ethyl acetate was then removed using a rotary evaporator at 65 ° C under a vacuum of 50 mm Hg. (b) Preparation of vinyl urethane (VU) was performed using the method described in Example 11 of EP 0 059 649. (c) A series of formulations were prepared with a comonomer concentration and composition as shown in the following Table 1. To the monomer mixture was added the catalyst component as follows: Weight percent canferquinone 0.73 dinethylaminoethyl methacrylate (DHAEH) 0.49 t-butyl perbenzoate 0.98 'Topanol' 0 to 200 ppm on final composition. 467 040 14 This addition and subsequent actions with the composition were performed under a sodium gas-based discharge lamp.

The evaluation of the binding strength on samples with the above formulations was performed using the procedure described in the British Dental Journal 1985, p. 93-95, with the difference that the composite reinforcing material used in connection with the barrier agent composition was "Occlusin '(trademark of Imperial Chemical Industries PLC). The samples were cured by irradiation with a tungsten halogen lamp with a tinted reflector and a dichromatic filter which eliminated led radiation and which exhibited an intensity of 1000 Wm'2 and with a curing time of 30 s.

'Topanol' is a trade name for 2,6-di-t-butyl-4-methylphenol from Imperial Chemical Industries PLC 15 4 6 7 0 4 Û I wt% I b, d I phosphate ester phosphate- | samonomer ln (âš: ¥ rka I I ester I I '' inner I outer: S: (deep) I (upper) - I »~ - I. '. |...

I Ro - P - oH I 10 I (1) TEGDM 8.o_I _-_ 3.6 I 18.146.4 I | I lo ”: (11) vIr / 'rrzcnn e.o¿a.s I 14.z_I¿s.2' OH I I (5o) (5o) I I I I I I I I weight proportion I I I I 5 80 7 I I | I 0 O O I I | I | || || I I.

I Ro-II-oumo-P-oRmo-P-ox I 35 Inn) rnsnu '9.a_I_-4.e I 12.1¿3.1 I | | I I so !! mv) vu / rzcnu: Lai-Ina I 13.2¿s.s I on on on I I (5o) <5o) I I J I _ | I weight proportion 'IIII 24 48 4 IIII ogo IIIIUIIII Ro-P-clmo-P-ORI-Ro-P-oa I 201 * I (v) vU /' rncnu 3.4_-I_-1.5 I a.1¿2.o I l | I I (5o) (5o) I I cl c on I I I | I I I | magnifying glass I I I "s <= ° == nb ° na" Itill 25: I | (35) fl in ethanol) | + I I I I I IEGDII I | I I I f fl s 3 fila f fl s ° _ chips Anm, g R: CH2'C-C-'0CH2CH-, C32 'C -C-O-CHCHZ-! according to the present invention I! TEGDH 'triethylene glycol dimethacrylate binder applied as a 20% by weight solution in ethanol. 467 040 1 ”Example 2 A binder formulation was prepared as described in Example 1 but with the following composition.

Parts by weight of phosphate ester (Example 1a) 9.78 TEGDH 90.22 camphorquinone 0.73 dibutyltin dilaurate 0.49 t-butyl perbenzoate 0.98 'Topanol' 0 to 200 ppm A sample of the above composition was cured and evaluated as described in Example 1 and was found to have a binding strength similar to that of Table 1 (i).

Example 3 A series of binder compositions were prepared as described in Example 1 but using a variety of tin compounds instead of DMAEH. Samples of the compositions were evaluated for curing time using the above-described oscillating rheometer technique.

Parts by weight of phosphate ester (Example 1a) 15 TEGDH 85 camphorquinone 0.75 tin compound 0.5 10 Tin compound none * dibutyltin diacetate dioctyltin dioacetate tributyltin acetate acetate tributyltin methacrylate bis (tributyltin oxide) tributyltin methoxide 30% Co .

Claims (10)

10 15 20 25 30 35 467 040 ia Patent claim 1. One-component, with visible light curable. liquid binder composition having a viscosity lower than 25 cP at 25 ° C, characterized in that it comprises (a) 2-20 parts by weight of at least one. substantially pure phosphate ester of the formula cnfcazl) .co.o.R2.oP (o) (ou) 2, 1 adult 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 (CH3) -CH2- and (b) 98-80 parts by weight of at least one ethylenically unsaturated monomer copolymerizable with the phosphate ester and an effective amount of a visible light activated catalyst. A composition according to claim 1, characterized in that R1 is a methyl group. of that Composition according to Claim 1 or 2, characterized in that R 2 is a propylene group. Composition according to any one of claims 1-3. k n a n e t e c k - n a d that the visible light activated catalyst contains an α-diketone. A composition according to claim 4, the diketone is camphorquinone. k ä n n e t e c k n a d of att Composition according to any one of claims 1-5. characterized in that the visible light activated catalyst contains an organotin compound. Composition according to any one of claims 1-6. characterized in that the visible light activated catalyst contains an organic peroxide. A composition according to any one of claims 1-7. know that the amount of impurity in the phosphate ester is less than 2% by weight. 19 - _ 467 040 Composition according to any one of claims 1-8. know that the concentration of phosphate ester is 5% by weight or more. Use of an adhesive composition according to any one of claims 1-9, which comprises coating a surface of a tooth with the composition and irradiating the composition at room temperature with visible light of a wavelength in the range 400-500 nm.