GB2393444A - Compositions comprising photoinitiator and oxetane compound - Google Patents

Abstract

An energy curable composition comprises a photoinitiator and a polymerisable compound of formula (I): <EMI ID=1.1 HE=37 WI=76 LX=752 LY=799 TI=CF> <PC>where: R<1> represents a C1 - C4 alkyl group, an aryl group or an aralkyl group; R<2> represents a group of formula -O-R<3> or a group R<4>; R<3> represents a C1 - C20 alkyl group, a C2 - C20 alkenyl group, an aryl group, an aralkyl group, a polyalkylene oxide group or a poly(lactone group); R<4> represents a C1 - C20 alkyl group, an aryl group or an aralkyl group; x is a number greater than 1 and no greater than 4; and (x + y) = 4. The composition may be used in printing ink or varnish.

Description

CATIONICALLY CURABLE COMPOSITIONS

The present invention relates to the use of a series of oxetane derivatives which may be employed as all or part of the polymerisable component of cationically 5 photopolymerisable compositions, especially for use in surface coating applications, such as printing inks and varnishes, and which are intended to be cured by polymerization initiated by radiation.

Photocurable compositions are cured by exposure to radiation, usually ultraviolet radiation, and include for example, lacquers which may be applied to wood, 10 metal or similar substrates by suitable techniques such as roll coating or curtain coating.

They may also be formulated as inks or varnishes, for example to be applied by techniques such as letterpress, offset lithography, rotogravure printing, silk screen printing, inkjet or flexographic printing. Printing, depending on the particular printing technique, is applicable to a wide range of substrates which include paper, board, glass, 15 plastics materials or metals. Other application areas will include adhesives, powder coatings, circuit boards and microelectronic products, stereolithography, composites, optical fibres and liquid crystals.

Initiation of polymerization in a monomer or prepolymer may be effected in a number of ways. One such way is by irradiation, for example with ultraviolet radiation, 20 in which case it is normally necessary that the polymerisable composition should contain an initiator, commonly referred to as a "photoinitiator", or alternatively by an electron beam. There are two main types of curing chemistry which can be used in this process; free radical and cationic. The compounds of the present invention are particularly useful in cationic photoinitiation.

25 Among the monomers used for energy-initiated cationic polymerization, the most common are the epoxides and vinyl ethers, although, in recent years, proposals have been made to use oxetane compounds for this purpose, for example, as described

in US6,121,342, US6,015,914, US5,882,842, US5,852,138, US5,674,922, US5, 463,084, US5,194,467, US4,456,717, US4,375,825 and US3,835,003. Ofthese, the closest to the present invention is currently thought to be US6,121, 342, which proposes the use of silane compounds of formula X3-Si-R , where X is a hydrolysable 5 group and R is a group containing an oxetanyl group. In practice, the groups containing an oxetanyl group and represented by R are groups having the formula: 6 /O\ 7

H2 where R6 is hydrogen or an alkyl group, and R7 is an aLkylene group, the most preferred compound apparently being: C2H5C/ \C3H6/

These compounds are said to have silicone-like properties and to cure to a very hard finish. However, these compounds have a relatively low reactivity and cure relatively slowly, which adversely affects the economics of any process employing them. 15 We have now discovered a series of compounds which may be used as all or part of the polymerisable component of cationically curable compositions and which retain the desirable properties on cure of these known compounds but which are highly reactive. The compounds used in the present invention have the formula (I):

[ -TO:Si R y (I) where: R1 represents a C1 - C4 alkyl group, an aryl group or an aralkyl group; R2 represents a group of formula {)-R3 or a group R4; 5 R3 represents a C1 - C20 alkyl group, a C2 - C20 alkenyl group, an aryl group, an aralkyl group, a polyalkylene oxide group or a poly(lactone) group; R4 represents a C1 - C20 alkyl group, an aryl group or an aralkyl group; x is a number greater than 1 and no greater than 4; and (x+y)=4. 10 The invention thus provides an energy curable composition comprising a photoinitiator and a polymerisable compound of formula (I), as defined above.

In the compounds of the present invention, where R1 represents an alkyl group, this may be a straight or branched chain group having from 1 to 4 carbon atoms, and examples include the methyl, ethyl, propyl, isopropyl, butyl, sec-butyl and t-butyl 15 groups, of which the methyl, ethyl and propyl groups are preferred, the ethyl group being most preferred.

Where R1, R3 or R4 represents an aryl group, this preferably has from 6 to 10 carbon atoms in one or more aromatic carbocyclic rings (which, if there are more than one, may be fused together). Such a group may be substituted or unsubstituted, and, if 20 substituted, the substituent(s) is preferably an alkyl group (as defined above in relation

to R1), or an alkoxycarbonyl or alkoxy group (as defined below). Where there are substituents, the number of such substituents is not critical, being limited only by the number of substitutable positions and possibly by steric constraints. In general, the number of substituents is preferably from 1 to S. more preferably from 1 to 3. however, 5 the unsubstituted aryl groups are normally preferred. Preferred aryl groups are the phenyl and naphthyl (1- or 2-) groups, the phenyl group being most preferred.

Examples of alkoxy groups which may be substituents on the aryl groups include straight or branched chain groups having from 1 to 4 carbon atoms, for example the methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy and t-butoxy groups, of 10 which the methoxy, ethoxy and propoxy groups are preferred.

Examples of alkoxycarbonyl groups which may be substituents on the aryl groups include straight or branched chain groups having from 2 to 5 carbon atoms, for example the methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, sec-butoxycarbonyl and t-butoxycarbonyl groups, of which the 15 methoxycarbonyl, ethoxycarbonyl and propoxycarbonyl groups are preferred.

Where R1, R3 or R4 represents an aralkyl group, this is an alkyl group having from 1 to 4 carbon atoms which is substituted by one or two aryl groups as defined and exemplified above, which may be substituted or unsubstituted, as described above.

Examples of such aralkyl groups include the benzyl, a-phenylethyl, pphenylethyl (= 20 phenethyl), 3-phenylpropyl, 4-phenylbutyl, diphenylmethyl, 1-naphthylmethyl and 2 naphthylmethyl groups, of which the benzyl group is preferred.

Where R3 or R4 represents an alkyl group, this may be a straight or branched chain group having from 1 to 20, preferably from 1 to 10, carbon atoms, and examples include the methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, pentyl, isopentyl, 25 neopentyl, 2-methylbutyl, 1ethylpropyl, 4-methylpentyl, 3-methylpentyl, 2 methylpentyl, 1methylpentyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 1, 2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 2-ethylbutyl, hexyl, isohexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl, pentadecyl, octadecyl, nonadecyl and

icosyl groups, but preferably the methyl, ethyl, propyl, butyl, hexyl and octyl groups, for example the methyl or octyl group.

Where R3 represents an alkenyl group having from 2 to 20, preferably from 2 to 10, more preferably from 2 to 6 and most preferably from 2 to 4, carbon atoms, this may 5 be a straight or branched chain group, and examples of such groups include the vinyl, 1-

propenyl, allyl, isopropenyl, methallyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl, tridecenyl, pentadecenyl, octadecenyl, nonadecenyl and icosenyl groups, but preferably the allyl, methallyl and butenyl groups, and most preferably the allyl group.

10 Where R3 represents a polyalkylene oxide group, this may be a group in which a polyalkylene oxide is attached to the silicon atom of the compound of formula (I) via a terminal oxygen atom and in which the other terminal hydroxy group is preferably etherified, for example a mono alkyl ether of poly(ethylene glycol), a mono alkyl ether of poly(propylene glycol), a mono alkyl ether of poly(tetrahydrofuran). These are most 15 commonly available as the methyl and ethyl ethers, which are thus preferred, although higher alkyl ethers, for example the propyl and butyl ethers may also be used.

Where R3 represents a poly(lactone), this is a group formed by the ringopening polymerisation of a lactone and attached to the silicon atom of the compound of formula (I) via an oxygen atom at one terminal. As with the polyalkylene oxide groups, this 20 may be terminated at the other terminal, for example, with an alkyl group. For example, R3 might be a mono-adduct of poly(caprolactone), such as Tone M- 100 (ex. Union Carbide) . x is a number greater than 1 but not exceeding 4, provided that (x + y) = 4.

Thus, y may be O or a number less than 3. The resulting compound is, therefore, 25 multifunctional, i.e. it contains, on average, more than one polymerisable group per molecule. In the hypothetical instance of considering an individual molecule, of course, these numbers, represented by x and y, are integral. However, in the real world, looking at a bulk product, this will be a mixture of compounds in which the values of x and y may vary, so that the measured value of either of these values is likely to be non

integral. In the context of the present specification, we are concerned only with

measured, not hypothetical, values. We prefer those compounds where the value of x is at least 2, more preferably at least 3, y then being determined as (4-x). Most preferably x is about 3 and y is correspondingly about 1.

5 We particularly prefer to use those compounds of formula (I) in which R1 represents a C1 - C4 alkyl group, a phenyl group, a benzyl group, a phenylethyl group or a 3-phenylpropyl group, more preferably a C1 - C4 alkyl group, and most preferably an ethyl group.

We also prefer those compounds of formula (I) in which R2 represents a phenyl l 0 group or a C1 - C8 alkyl group (preferably methyl or ethyl group, more preferably a methyl group), or a group of formula -o-R3, where R3 represents a Cl - C1o alkyl group, a C2 - C1 0 alkenyl group, a benzyl group, a phenylethyl group or a 3 phenylpropyl group, especially those compounds of formula (I) in which R2 represents a phenyl group, or in which R2 represents a group of formula -o-R3 and where R3 15 represents a C1 - Cg alkyl group, an allyl group or a methallyl group, preferably a methyl, ethyl, allyl or methallyl group, most preferably a methyl group.

Particularly preferred compounds are those compounds of formula (I) in which: R1 represents a C1 - C4 alkyl group, a phenyl group, a benzyl group, a phenylethyl group or a 3-phenylpropyl group; 20 R2 represents a phenyl group or a C 1 - C8 alkyl group (preferably methyl or ethyl group, more preferably a methyl group), or a group of formula -o-R3, where R3 represents a C1 - Clo alkyl group, a C2 - C1o alkenyl group, a benzyl group, a phenylethyl group or a 3-phenylpropyl group, especially those compounds of formula (I) in which R2 represents a phenyl group, or in which R2 represents a group of formula 25 -o-R3 and where R3 represents a C1 - C8 alkyl group, an allyl group or a methallyl

group, preferably a methyl, ethyl, allyl or methallyl group, most preferably a methyl group; and x is a number greater than 1 and no greater than 4, preferably at least 2, more preferably at least 3 and most preferably about 3.

5 Still more preferred compounds are those compounds of formula (I) in which: R1 represents a C1 - C4 alkyl group; R2 represents a phenyl group or a C1 - C8 alkyl group (preferably methyl or ethyl group, more preferably a methyl group), or a group of formula -o-R3, where R3 represents a C 1 - C1o alkyl group, a C2 - C 10 alkenyl group, a benzyl group, a 10 phenylethyl group or a 3-phenylpropyl group, especially those compounds of formula (I) in which R2 represents a phenyl group, or in which R2 represents a group of formula -o-R3 and where R3 represents a C1 - Cal alkyl group, an allyl group or a methallyl group, preferably a methyl, ethyl, allyl or methallyl group, most preferably a methyl group; and 15 x is a number greater than 1 and no greater than 4, preferably at least 2, more preferably at least 3 and most preferably about 3.

The most preferred compounds are those compounds of formula (I), in which: R1 represents an ethyl group; R2 represents a phenyl group or a C1 - Cal alkyl group (preferably methyl or ethyl 20 group, more preferably a methyl group), or a group of formula -CART, where R3 represents a C1 - C1o alkyl group, a C2 - C1o alkenyl group, a benzyl group, a phenylethyl group or a 3-phenylpropyl group, especially those compounds of formula (I) in which R2 represents a phenyl group, or in which R2 represents a group of formula -o-R3 and where R3 represents a C 1 - Cal alkyl group, an allyl group or a methallyl

group, preferably a methyl, ethyl, allyl or methallyl group, most preferably a methyl group; and x is a number greater than 1 and no greater than 4, preferably at least 2, more preferably at least 3 and most preferably about 3.

5 The compounds of formula (I) used in the present invention are known compounds, which have previously been proposed for use in the stabilization of polycarbonates, as described, for example, in US 4,375, 525, US4,456,717 and US5,194,467. They may be prepared as described in these US patents, the disclosures

of which are incorporated herein by reference.

10 The energy curable composition of the present invention comprises at least a photoinitiator and a polymerisable compound of formula (I), as defined above. In addition, it may contain any one or more of other well known materials which are commonly incorporated into such compositions to provide particular desired properties either in the curable composition or in the final cured product.

15 Non-limiting examples of such other components are as follows: Reactive diluents These, like the compounds of formula (I), are polymerisable under cationic, energy (e.g. W) induced conditions. They are commonly added to decrease the viscosity of the curable composition, but may also be incorporated in order to modify, 20 in a controlled manner, the properties of the final cured product. There is no particular restriction on the nature of the reactive diluents used in the present invention, and any of those compounds used for this purpose in the prior art may equally be used here.

Examples include compounds having an energy-induced, cationically polymerisable group, such as a vinyl, vinyloxy, epoxy or oxetanyl group. Specific examples of such 25 compounds include ethyl vinyl ether, diethyleneglycol divinyl ether, tri-ethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, butanediol divinyl ether, butanediol monovinyl ether, trimethylol trivinyl ether 1,2-epoxy-4-[1,2epoxycyclohex-4-yl-

carbonyloxymethyl]cyclohexane (Uvacure 1500 - Uvacure is a trade mark), bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, 1,4-bis[(3ethyl-3-oxetanylmethoxy)

methyl Benzene, 3 -ethyl-3 -allyloxymethyloxetane, 3 -ethyl-3 hexyloxymethyloxetane and 3-ethyl-3-[3-(triethoxysilyl)propoxymethyl] oxetane. The epoxy and oxetane compounds are generally more preferred since they give cured products having good chemical and heat resistance as well as good adhesion.

5 Other monomers and oligomers The composition may, if desired, contain other radiation-curable monomers and/or oligomers. These are preferably ethylenically unsaturated compounds, particularly acrylate compounds. Examples of suitable acrylate oligomers include aliphatic or aromatic urethane acrylates, polyether acrylates, polyester acrylates and 10 epoxy acrylates (such as bisphenol A epoxy acrylate). Examples of suitable acrylate monomers include hex anediol diacryl ate, trimethylolpropane tri acryl ate, di -

trimethylolpropane tetraacrylate, di-pentaerythritol pentaacrylate, polyether acrylates, such as ethoxylated trimethylol propane triacrylate, glycerol propoxylate triacrylate, ethoxylated pentaerythrito l tetraacryl ate, and epoxy acrylates such as di anol di acryl ate 15 (= the diacrylate of 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, Ebecryl 150 from UCB) and glycol diacrylates such as tripropylene glycol diacrylate.

Initiators The composition of the present invention will contain, in addition to the compound or compounds of formula (I), an initiator, sometimes referred to as a 20 'photoinitiator'. Such initiators are well known in the art, and there is no particular restriction on the choice of initiator for use in the present invention. A number of suitable cationic photoinitiators are commercially available and include onium salts, which generate initiating (acidic) species under the action of W light. Typical, commercially available photoinitiators are usually based upon diaryliodonium salts (e.g. 25 Irgacure 250, ex. Ciba Geigy) or triarylsulphonium salts (e.g. Uvacure 1592, ex. UCB Chemicals) with counterions such as SbF6-, PF6-, AsF6-, BF4-. It is also quite common to add sensitisers to the compositions; including anthracene, perylene, phenothiazine, thioxanthone, xanthone, Michlers ketone. More information on the choice of photoinitiators is provided in Chapter 3 of"Exploring the Science, Technology and

Applications of W and EB Curing", R.S. Davidson, Sita Technology Ltd., London, 1999, the disclosure of which is incorporated herein by reference.

Pigments In its broadest sense, the present invention provides an energy-, e.g. radiation 5 curable composition, which may be, for example, a printing ink or varnish composition.

That is to say, a composition which is curable by the application of suitable radiation such as ultra-violet (UV) radiation or electron-beam radiation. Such a composition may be only a substantially colourless curable varnish or a substantially colourless radiation-

curable base to which a colorant may be added. In the context of the present invention, 10 the term 'colorant' covers both materials which endow an actual visual colour and/or another optical property such as fluorescence. Colorants are typically included in amounts of up to 20% of total colorant(s) by weight of the total composition.

Broadly speaking, colorants may be considered as falling into two classes, namely dyes, which are substantially soluble in the ink composition, and pigments, 15 which are dispersed in the ink composition in the form of fine particles, if necessary with the aid of a suitable dispersant. Pigments may be selected from a wide range of classes, for example, Pigment Red 57:1, Pigment Red 52:2, Pigment Red 48:2, Pigment Blue 15:3, Pigment Green 7, Pigment Yellow 83, Pigment Yellow 13, Pigment White 6, Pigment Black 7. A non-exhaustive list of examples of such pigments include the 20 following from the Irgalite range ex CIBA: Rubine L4, Bordeaux CM, Red 2BP, Blue LO, Green GLN, Yellow B3R and yellow LBG; as well as Tioxide RHD6 (ex Tioxide) and Special Black 250 (ex Degussa). Other examples of suitable pigments are given in "Printing Ink Manual", fourth edition, Leach R. H. et a/. (eds.), Van Nostrand Reinhold, Wokingham, (1988), the disclosure of which is incorporated herein by reference.

25 Other additives Printing ink and varnish compositions according to the present invention optionally may also comprise one or more minor ingredients, for example, surfactants, levelling additives, photoinitiator stabilisers, wetting agents and pigment stabilisers.

The latter may for example be of polyester, polyurethane or polyacrylate types,

especially in the form of high molecular weight block co-polymers, and would typically be incorporated at from 2.5% to 100% by weight of the pigment. Suitable examples are Disperbyk 161 or 162 (ox BYK Chemie) or Solsperse ex Zeneca. Suitable photoinitiator stabilisers include those disclosed in EP-A-O 465 039.

5 Suitable surfactants are preferably of the non-ionic type, for example Fluorad FC430 (ex 3M Corp.). Such surfactants (when present) are preferably included in an amount of 0. 1% to 10% by weight of the total composition.

Compositions according to the present invention are preferably substantially free or totally free of organic solvent, the term "solvent" here meaning a compound which is 10 incorporated in the composition for the sole purpose of dissolving one or more components and which does not participate in the polymerization reaction, i.e. a reactive diluent is not considered a "solvent" in this context. Thus, they preferably contain less than 10%, more preferably less than 5%, especially less than 1% and most preferably less than 0. 1% of organic solvent(s) as expressed by weight of the total composition.

15 The formulation of the printing ink or varnish of the present invention may vary depending upon the substrate onto which it is to be applied, as is well known in the art.

There is no restriction on the nature of such substrates in the present invention.

The amount of the compound or compounds of formula (I) included in the composition of the present invention may vary over a wide range, depending, in part, on 20 the amount of the other ingredient or ingredients incorporated, as outlined above.

However, in general, we prefer that the amount of compound or compounds of formula (I) should be up to about 80% by weight of the whole curable composition. There is no particular minimum, although, if the amount is too low, the properties of the curable composition and of the final cured product will be dominated by the other components, 25 and the advantages of the present invention may not be fully appreciated. We suggest that a sensible minimum would be about 5% by weight and thus a preferred range is from 5 to 80% by weight of the compound or compounds of the present invention based on the weight of the whole curable composition. A more preferred range is from 20 to 60% by weight.

The application and curing of the compositions of the present invention may be carried out using techniques well known to those skilled in the art, for example, as described in "Printing Ink Manual", fourth edition, referred to above.

The invention is further illustrated by the following non-limiting Examples.

5 EXAMPLE 1

Synthesis of the silicon adduct, MeSi(Ox)3 OiSi CH3 The adduct was simply formed by the reaction of TMPO (3-ethyl-3-

hydroxymethyloxetane) with methyltrichlorosilane as follows.

10 TMPO (20.88 g, 0.18 mol) and triethylamine (18.24 g, 0.18 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere.

Methyltrichlorosilane (8.94 g, 0.06 mol) dissolved in diethyl ether (50 ml) was added dropwise over one and half hours at a temperature of 0 to 5 C. After the end of the addition, stirring was continued at 0-5 C for 30 minutes, and then the temperature was 15 increased to room temperature.

Precipitated triethylamine hydrochloride was removed by filtration. The filtered mixture was washed several times with 20 ml aliquots of water. The organic phase was collected and the solvent was removed under reduced pressure.

The residue was a clear liquid and the yield was 21.20 g (0.05 mol. 91. 1wt%).

EXAMPLE 2

The reaction product of 3-ethyl-3-methyloloxetane with dichlorodimethylsilane /osi (CH3)2 3-Ethyl-3-methyloloxetane (17.4 g, 0. 15 mol) and triethylamine (15.15 g, 5 0.15 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere. Dichlorodimethylsilane (9.72 g, 0.075 mol) dissolved in diethyl ether (50 ml) was added dropwise over one and a half hours at a temperature of 05 C. After the end of the addition, the reaction mixture was kept stirring at O-5 C for 30 minutes before allowing the temperature to increase to room temperature.

10 The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic phase was then separated and the solvent removed under reduced pressure.

The residue was a clear liquid and the yield was 18.9 g (87.5%).

EXAMPLE 3

15 The reaction product of 3-ethyl-3-methyloloxetane with Silicon tetrachloride /-:os' _ 4

3-Ethyl-3-methyloloxetane (23.2 g, 0.20 mol) and triethylamine (20.2 g, 0. 20 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere. Silicon tetrachloride (8.5 g, 0.05 mol) dissolved in diethyl ether (50 ml) was added dropwise over one and a half hours at a temperature of 0-5 C. After the end 5 of the addition, the reaction mixture was kept stirring at 0-5 C for 30 minutes before allowing the temperature to increase to room temperature.

The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic phase was then separated and the solvent removed under reduced pressure.

10 The residue was a solid and the yield was 21.7 g (89.0%).

EXAMPLE 4

The reaction product of 3-ethvl-3-methYloloxetane with Phenvltrichlorosilane oTs' _ _ 3 3-Ethyl-3-methyloloxetane (17.4 g, 0.15 mol) and triethylamine ( 15.15 g, 15 0.15 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere. Phenyltrichlorosilane (10.58 g, 0.05 mol) dissolved in diethyl ether (50 ml) was added dropwise over one and a half hours at a temperature of 05 C. After the end of the addition, the reaction mixture was kept stirring at 0-5 C for 30 minutes before allowing the temperature to increase to room temperature.

20 The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic phase was then separated and the solvent removed under reduced pressure.

The residue was a clear liquid and the yield was 19.8 g (87.8%).

EXAMPLE 5

The reaction product of 3-ethYI-3-methyloloxetane and octan-1-ol with methvltrichlorosilane >0- Nisi 5 Octan-l-ol (6.51 g, 0.05 mol) with triethylamine (15.15 g, 0.15 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere.

Methyltrichlorosilane (7.45 g, 0.05 mol) dissolved in diethyl ether (50 ml) was added dropwise over one hour at a temperature of 0-5 C. Then, 3ethyl-3-methyloloxetane (11.6 g, 0.10 mol) was added at the same temperature over 30 minutes. After the end of 10 the addition, the reaction mixture was kept stirring at 0-5 C for 30 minutes before allowing the temperature to increase to room temperature.

The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic phase was then separated and the solvent removed under reduced pressure.

15 The residue was a clear liquid and the yield was 17.7 g (87.6g).

EXAMPLE 6

The reaction product of 3-ethYI-3-methylolexetane and benzYI alcohol with methyltrichlorosilane /S\o lr si

Benzyl alcohol (5.4 g, 0.05 mol) with triethylamine (15.2 g, 0.15 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere.

Methyltrichlorosilane (7.45 g, 0.05 mol) dissolved in diethyl ether (50 ml) was added dropwise over one hour at a temperature of 0-5 C. Then, 3ethyl-3-methyloloxetane 5 (11.6 g, 0.10 mol) was added at the same temperature over 30 minutes. After the end of the addition, the reaction mixture was kept stirring at 0-5 C for 30 minutes before allowing the temperature to increase to room temperature.

The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic 10 phase was then separated and the solvent removed under reduced pressure.

The residue was a clear liquid and the yield was 17.8 g (93.7%).

EXAMPLE 7

The reaction product of 3-ethyl-3-methvloloxetane and allvl alcohol with methvltrichlorosilane MOCHA CH = CH2

Allyl alcohol (3.48 g, 0.06 mol) with triethylamine (18.2 g, 0.18 mol) were stirred together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere.

Methyltrichlorosilane (8.94 g, 0.06 mol) dissolved in diethyl ether (50 ml) was added dropwise over one hour at a temperature of 0-5 C. Then, 3ethyl-3-methyloloxetane 20 (13.9 g, 0.12 mol) was added at the sametemperature over 30 minutes. After the end of the addition, the reaction mixture was kept stirring at 0-5 C for 30 minutes before allowing the temperature to increase to room temperature.

1, The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic phase was then separated and the solvent removed under reduced pressure.

The residue was a clear liquid and the yield was 18.0 g (90.6%).

5 EXAMPLE 8

The reaction product of 3-ethvl-3-methyloloxetane and allyl alcohol with tetrachlorosilane [ /\0 Si OCH2 CH = CH2 Allyl alcohol (2.9 g, 0.05 mol) with triethylamine (20.2 g, 0.20 mol) were stirred 10 together in diethyl ether (250 ml) at 0-5 C under a nitrogen atmosphere.

Tetrachlorosilane (8.5 g, 0.05 mol) dissolved in diethyl ether (50 ml) was added dropwise over one hour at a temperature of 0-5 C. Then, 3-ethyl3-methyloloxetane (17.4 g, 0.15 mol) was added at the same temperature over 30 minutes. After the end of the addition, the reaction mixture was kept stirring at 0-5 C for 30 minutes before 15 allowing the temperature to increase to room temperature.

The precipitated triethylamine hydrochloride was removed by filtration. The product solution was washed several times with 20 ml aliquots of water. The organic phase was then separated and the solvent removed under reduced pressure.

The residue was a clear liquid and the yield was 19.1 g (88.8%).

EkAL\1P L E S 9 T O 12 An Assessment of the ExamnIe Materials in UVCurable Coatines A number of the products of the above Examples were evaluated in W-curable cationic varnishes according to the compositions set out in the following Table 1.

5 Table 1

Ex. 9 Ex. 10 Ex. 11 Ex. 12 Control Control Control Compound 48.0 % of Ex. 1 Compound 48.0 % of Ex. 3 Compound 48.0 % of Ex. 4 Compound 48.0 % of Ex. 8 Uvacure 47.9 % 47.9 % 47.9 % 47.9 % 95.9% 75.9 % 47.9 % Uvacure 4.0 % 4.0 % 4.0 % 4.0 % 4.0 % 4.0 % 4.0 % TegoRad 0.1% 0.1% 0.1% 0.1% 0.1% 0. 1% 0.1% TMPO 20.0%

OXT-221 48.0 %

Uvacure 1500 - a biscycloaliphatic epoxide from UCB of formula

o C\O Uvacurel 592 - triarylsulphonium salt photoinitiator from UCB TMPO 3-ethyl-3-methyloloxetane Tego Rad 2100 - a flow and levelling additive, ex. Tego Chemie.

5 Varnishes of the invention The varnishes containing the compounds produced in Examples 1, 3, 4 and 8 as about 50% of the polymerisable components, are compositions in accordance with the present invention.

Control 1 10 This varnish is based solely upon the biscycloaliphatic epoxide, Uvacure 1500, which is representative of the type of epoxide which is most commonly used in W cationically curable varnishes and inks.

Control 2 This varnish contains 20% TMPO, which is commercially available and allows 15 varnishes and inks with superior cure speeds to be prepared. Because of the hydroxyl group, amounts much greater than 20%(in a varnish) tend to reduce the cure response as a consequence of chain transfer. We have found that 20% TMPO in the simple varnish composition above promotes cure.

Control 3 20 OXT-221 has the formula:

It is a difunctional oxetane that we have found to be particularly reactive in W-

curable compositions (varnishes). Of the commercially available oxetane oligomers that we have evaluated it is by far the most reactive and, like the compounds of the 5 present invention, but unlike TMPO, can be used at relatively high concentrations in a curable composition.

Cure Performance The varnishes were coated on to Leneta unlacquered opacity charts with a No.0 K-Bar and cured through an FDS W-rig at 100 m/min with a lamp (medium pressure 10 mercury lamp) power of 40 W/cm. The number of passes through the rig to achieve a well cured film according to the thumb twist method were recorded. The cure of the films was also assessed by measuring the solvent resistance (number of methyl ethyl ketone double rubs required to disrupt the film). The solvent resistance was determined immediately after UV-curing and at various times after curing to assess the post cure.

15 Table 2 below provides the results.

Table 2

| Ex. 9 | Ex. 10 | Ex. 11 | Ex. 12 | Control 1 | Control 2 | Control 3 No. of passes 1 1 1 >3 >3 3 to achieve MEK Rubs 22 80 30 45 3 5 8 (zero time) MEK Rubs 59 10 15 31 MEK Rubs 54 23 29 48 (3 hours) MEK Rubs 61 70 90 N/A 65 71 71 (1 week) (Relative Humidity = 48%) As can be seen from the results above, the silicon-based monomers of the 5 present invention produce a varnish with markedly superior cure response compared with the control varnishes, both in terms of the number of passes required to achieve full cure and in terms of the high solvent resistance achieved directly after cure. Both these results are outstanding.

Claims (18)

CLAIMS:

1. An energy curable composition comprising a photoinitiator and a polymerisable compound of formula (I): Am> \Osi R2y (I) where: R1 represents a C1 - C4 alkyl group, an aryl group or an aralkyl group; R2 represents a group of formula -o-R3 or a group R4; R3 represents a C1 C20 alkyl group, a C2 - C20 alkenyl group, an aryl group, an aralkyl group, a polyalkylene oxide group or a poly(lactone) group; R4 represents a C1 - C20 alkyl group, an aryl group or an aralkyl group; x is a number greater than 1 and no greater than 4; and (x + y) = 4

2. A composition according to Claim 1, where x is a number of at least 2.

3. A composition according to Claim 1, where x is a number of at least 3.

4. A composition according to Claim 1, where x is about 3 and y is about 1.

5. A composition according to any one of Claims l to 4, in which R1 represents a Cl - C4 alkyl group, a phenyl group, a benzyl group, a phenylethyl group or a 3-

phenylpropyl group.

6. A composition according to Claim 5, in which R1 represents a C1 - C4 alkyl group.

7. A composition according to Claim 6, in which R1 represents an ethyl group.

8. A composition according to any one of Claims I to 7, in which R2 represents a phenyl group or a group of formula -o-R3, where R3 represents a C 1 - C 10 alkyl group, a C2 - Clo alkenyl group, a benzyl group, a phenylethyl group or a 3-

phenylpropyl group.

9. A composition according to Claim 8, in which R2 represents a phenyl group.

10. A composition according to Claim 8, in which R3 represents a C1 - C8 alkyl group, an allyl group or a methallyl group.

11. A composition according to Claim 8, in which R3 represents a methyl, ethyl, allyl or methallyl group.

12. A composition according to Claim 8, in which R3 represents a methyl group.

13. A composition according to any one of Claims 1 to 12, in which R3 represents a C1 - Cg alkyl group.

14. A composition according to Claim 13, in which R3 represents a methyl or ethyl group.

15. A composition according to Claim 14, in which R3 represents a methyl group.

16. A composition according to Claim 1, where said polymerisable compound is a compound of formula (II):

SO Thai (CH3)y (II) where x is a number of at least 2 and no greater than 4 and y is (4-x).

17. A composition according to Claim 16, where x is about 3 and y is about 1.

18. A composition according to any one of the preceding Claims, which is a printing ink or varnish.