In the past 20 years, radiation curing has become more and more popular since it provides low or zero volume emission and high productivity. This new technology has been widely used in coatings, inks and adhesives. Radiation curable compositions are typically mixtures of monomers, oligomers, photoinitiators, or additives which are applied to the substrates and cured in place via ultraviolet light.

The adhesion between the substrates and the cured compositions varies from system to system. Various additives have been used to improve adhesion. Silane agents have been widely used to improve adhesion in traditional coatings and composites based on epoxy chemistry. However, the application and selection of silane agents depends on cure mechanisms. In the radiation curable case, only one compound, gamma-methacryloxypropyl trimethoxysilane, is compatible with the cure mechanism and available.

Gamma-methacryloxypropyl trimethoxysilane monomer is a well known commercially available coupling agent for bonding coatings to substrates. The coupling agent is mixed with other copolymerizable monomers such as (meth)acrylates, i.e., acrylates, methacrylates, or mixtures thereof, and the mixture of monomers is applied to a surface and cured.

The methacryloxypropyl trimethoxysilane coupling agent of the prior art is prepared from allyl methacrylate, a volatile and odorous compound. The presence of the allyl methacrylate starting material along with the methacryloxypropyl trimethoxysilane monomer coupling agent also causes odor problems with the cured coatings. Other silane-based coupling agents are available, but are mainly directed to two-part, non-(meth)acrylate systems. See

Waldman, Silane Coupling Agents Improve Performance, Modern Paints and Coatings, Feb., 1996.

PCT publication WO 96/12749 of 2 May 1996 shows silane oligomers and radiation curable coating compositions for optical fiber coating. The silane oligomers are high in molecular weight (500-11,000) and a high level of silane oligomer is needed, typically about 5-99t of the coating composition. These silane oligomers are typically prepared based on urethane chemistry and urethane linkage.

Derwent abstract 95-225640/30 relating to DE-4 416 857 of 29 June 1995 shows hydrolysable and polymerizable silane(s) useful in coating, adhesive, and moulding compositions and composites prepared from reactive silane and unsaturated compound and polycondensed to hereto polysilicic acid compound or polymerized. These silanes have carboxylic acid functional groups for use in the radiation-hardenable binders. These silane agents are prepared from hydroxy containing compounds and acid anhydride containing silanes.

It is an object of this invention to provide coupling agents which have reduced volatility and odor.

It is another object to provide coupling agents which match the adhesion performance of the prior coupling agents, but avoid the volatility and odor problems.

A further object is to provide improved W curable coating compositions which have reduced volatility and odor.

These objects, and others as will become apparent from the following disclosure, are achieved by the present invention which comprises in one aspect compounds of the formula wherein - R1 = H, -CH3

- each of the Y, which may be the same or different when n is higher than 1, represents an alkylene oxide unit of the formula wherein R2 is H, -CH31 -CH2CH3 or -CH2CH2CH3 - n = 1-10 - X = halogen, (C1-C6) alkyl, (C1-C6) alkoxy, or aromatic radical, wherein each of the three X substituents can be the same or different.

In particular : X may be advantageously C1 or methoxy or ethyl ; R1 may be methyl ; and R2 may be H or methyl and n may be from 2 to 5.

In another aspect, the invention comprises a method of making such compounds of formula (I) comprising reacting (A) a compound of the formula wherein R1, Y and n are as defined above, and (B) HSiX3 (III) wherein X is as defined above, in the presence of a transition metal catalyst, for instance a platinum catalyst, such as H2PtC16.

A polymerization inhibitor, such as 4-methoxy- phenol, may be present.

Compounds of formula (II) can be prepared by reacting a compound of the formula HO[YI, CH2CH=CH2 (IV) wherein Y and n are as defined above, with acrylic or methacrylic acid.

The novel monomer compounds are the reaction product of a silane of the formula HSiX3 (III) and an alkoxylated (alk)acrylate of the formula in the presence of a transition metal catalyst.

Suitable silanes of formula (III) include trichlorosilane, tribromosilane, trifluorosilane, trimethoxysilane, triethoxysilane, trimethylsilane, triethylsilane and triphenylsilane. The preferred silane is trimethoxysilane.

Suitable alkoxylated (alk)acrylates are the reaction product of alkoxylated allyl alcohol and (meth)acrylic acids. The alkoxylated allyl alcohols are prepared by reacting alkylene oxide with allyl alcohol.

Suitable alkylene oxides are ethylene oxide, propylene oxide, which is preferred, butylene oxide, and pentylene oxide. The number of alkylene oxide groups, n, can be 1 to 10, with 2 to 5 being preferred.

Suitable (meth)acrylic acids are acrylic acid and methacrylic acid, with the latter preferred.

The transition metal catalyst is preferably platinum based, for example, H2PtC16. Other suitable catalysts are, for example, rhodium-containing compounds.

The present invention also encompasses the use of a compound (I) as defined above as a monomer in a free radically curable composition, said compound (I) being advantageously introduced as a coupling agent or an adhesion promoter ; a method of using a compound (I) as defined above, characterized by the fact that it comprises adding the compound to a coating composition in an amount capable of promoting adhesion of the composition to a substrate ; a

free radically curable composition comprising at least one compound of formula (I), in particular UV curable coating composition ; a composition comprising a copolymer of a compound of formula (I) and of one or more unsaturated monomers, said composition being useful as a coating or adhesive composition having adhesion properties in relation to a substrate ; a free-radically cured composition having adhesion properties in relation to a substrate, said composition being obtained by curing anyone of the compositions as defined above ; and articles, in particular comprising glass, coated with anyone of the compositions as defined above.

The monomers of the invention are preferably used in admixture with other unsaturated monomers and the mixture of monomers is applied to a surface of an article and cured to form a coating or adhesive.

The surfaces to which the coating compositions of the invention can be applied include glass, metal, wood, steel, plastic and the like. The new monomers can be used in the same manner as the prior methacryloxypropyl trimethoxysilane monomer with the advantage of imparting lower odor and reduced volatility to the free radically curable coating compositions.

The W curable coating compositions may contain 0.5-10 parts by weight of at least one compound (I) of this invention, 0.5-15 parts by weight of photoinitiator or photoinitiator mixture, and 50-90 parts by weight of (meth)acrylate monomers, oligomers or monomer/oligomer mixture. The various components can be mixed as in the regular composition and applied to the substrate by roller coating, spraying, or any other method. The applied coatings can be cured by irradiation with W light.

Alternatively, the silane agent could be applied first to the substrate followed by regular coating application and curing.

The following examples illustrate several embodiments of the invention.

EXAMPLE 1 Svnthesis of Pronoxylated Allvl Methacrylate Propoxylated allyl alcohol (5 propylene oxide units per molecule) (1344.8 g), Dow Chemical brand, methacrylic acid (448.5 g), 4-methoxyphenyl (6.75 g), methane sulfonic acid (70%, 33.75 g), and heptane (405.5 g) were added to a reactor and stored at room temperature. Air sparge was applied. Then, the mixture was heated to reflux and water generated was removed via azeotrope. After the reaction was complete (no more water formation), the mixture was neutralized with 25% NaOH and washed twice with 25% NaOH. The final product, propoxylated allyl methacrylate having 5 propylene oxide units per molecule, was obtained by removing the heptane solvent under reduced pressure. Yield was 1532.4 grams.

EXAMPLE 2 Synthesis of Propoxylated Allvl Methacrylate Example 1 was repeated using having 2 propylene oxide units per molecule of propoxylated allyl alcohol, forming propoxylated allyl methacrylate having 2 propylene oxide units per molecule was obtained.

EXAMPLE 3 Synthesis of Propoxylated Methacryloxypropyl Trimethoxysilane Monomer from Example 2 (104.0 g), trimethoxysilane (55.0 g), 4-methoxyphenol (0.16 g), platinum catalyst (4 drops, made by dissolving 2.0 g H2PtC16 in 98.0 g isopropanol) were added to a three neck flask and stirred.

After 4-methoxyphenol was dissolved, air sparge was applied

and the mixture was heated to 65"C. The addition reaction took place with the observation of exotherm. The reaction was followed by FTIR with the disappearance of Si-H stretch at 2200 cm 1. The reaction was completed in 8.0 hrs.

EXAMPLE 4 Synthesis of Propoxylated Methacrvloxv Propyl Triethylsilane Example 3 was repeated using equal moles of triethylsilane. Propoxylated methacryloxy propyl triethylsilane was obtained.

While the invention has been described in great detail, various alternatives and improvements should become apparent to those skilled in this art without departing from the spirit and scope of the invention as set forth in the claims.