The present invention refers to a novel radiation curable composition comprising 2-hydroxy-3- butenoic acid and/or at least one ester of 2-hydroxy-3-butenoic acid and at least one additional compound selected from radiation curable monomers, oligomers and polymers.

Chemical compounds having one or more carbon-carbon double bonds (unsaturations) are well known in the art and used as reactants and chemical building blocks in a wide variety of applications, such as drying and/or heat curing and/or UV, IR and EB curing paints, enamels, putties, lacquers, varnishes, adhesives and inks, esters and polyesters, latex, fibres, textiles and so on, as well as in for instance moulding and casting compositions and the like. There is, however, despite the large amount of commercially available unsaturated compounds and derivatives thereof, due to for instance environmental concerns and legislation and/or new application areas, a substantial and ever growing demand for novel, safer, more efficient and/or more versatile compounds having one or more carbon-carbon double bonds. A major search, for safer unsaturated compounds for use in polymeric materials, is directed to suitable replacements for presently used unsaturated compounds, such as acrylic and allylic compounds.

An object of the present invention is to provide a novel unsaturated compound having at least one carbon-carbon double bond. A further object is to provide a suitable, complement and/or replacement for compounds such as acrylic, methacrylic and crotonic ester, allyl and methallyl ethers, and other compounds comprising at least one vinyl unsaturation. Yet a further object is to provide a said suitable complement and/or replacement obtained from a renewable source, such as a biomass.

It has now quite unexpectedly been found that 2-hydroxy-3-butenoic acid and its esters provide excellent radiation curing compositions, wherein said acid and/or said ester is used as complement to or substitute for radiation curable compounds having for instance one or more carbon-carbon double bonds, such as acrylic, methacrylic and crotonic esters, allyl or methallyl ethers, and/or compounds such as vinyl monomers, oligomers and polymers. 2-Hydroxy-3- butenoic acid and its methyl ester, methyl vinyl glycolate, are easily obtained from biomass via for instance lactic acid. Said 2-hydroxy-3-butenoic acid and said methyl vinyl glycolate can easily via esteriflcation or transesterification with mono, di, tri and polyalcohols, be transformed to a number of versatile compounds having one or more vinyl unsaturations. Embodiments of the present invention accordingly include compositions wherein at least one of the included components is 2-hydroxy-3-butenoic acid or an ester of 2-hydroxy-3-butenoic acid. Said ester is in various embodiments a linear or branched alkyl ester, such as methyl or ethyl vinyl glycolate, or an ester of 2-hydroxy-3-butenoic acid and a monoalcohol, such as 2- ethyl-heptanol, 2-propyl-heptanol, 5-hydroxy-l,3-dioxane, 5-hydroxymethyl-l ,3-dioxane or 5- hydroxyethyl-l,3-dioxane. Further embodiments include esters of 2-hydroxy-3-butenoic acid and di, tri or polyhydroxy functional compounds, such as diols, triols, tetrols, pentols, hexols and hyperbranched dendritic polyols. These embodiments accordingly include esters, such as mono and diesters of diols, mono, di and triesters of triols, mono, di, tri and tetraesters of tetrols, mono, di, tri, tetra and pentaesters of pentols, and mono, di, tri, tetra, penta and hex- aesters of hexols as well as mono, oligo or polyesters of hydroxyfunctional compounds having seven or more hydroxyl groups.

Said additional compound is in embodiments of the present invention at least one acrylic, methacylic or crotonic ester having at least one carbon-carbon double bond, such as acrylic, methacrylic or crotonic mono and diesters of diols, mono, di and triesters of triols, mono, di, tri and tetraesters of tetrols, mono, di, tri, tetra and pentaesters of pentols, mono, di, tri, tetra, penta hexaesters of hexols and mono, di (oligo) or polyesters of hyperbranched dendritic polyols and hydroxyfunctional compounds having seven or more hydroxyl groups, and/or is at least one allyl or methallyl ether having at least one carbon-carbon double bond, such as mono and diethers of diols, mono, di and triethers of triols, mono, di, tri and tetraethers of tetrols, mono, di, tri, tetra and pentaethers of pentols, mono, di, tri, tetra, penta hexaethers of hexols and mono, di or polyethers of di (oligo) or polyesters of hyperbranched dendritic polyols and hydroxyfunctional compounds having seven or more hydroxyl groups.

Embodiments of said diol include, but are not limited to, compounds of formula HO-R-OH, wherein R is a linear or branched alkyl, cycloalkyl or aryl group, and can suitably be exemplified by butanediol, propanediol, heptanediol, pentanediol, hexanediol, dipropylene glycol, tri- ethylene glycol, cyclohexanedimethanol, 2-ethyl-2-butyl- 1,3 -propanediol, neopentyl glycol, 5,5-dihydroxymethyl-l,3-dioxane, xylylene glycol (benzene dimethanol), pentaerythitol spiro- glycol and by caprolactone diols and/or by a to a said diol corresponding polycarbonate diol. Further suitable embodiments of said diol include alkoxylated, such as ethoxylated, propox- ylated and/or butoxylated, neopentyl glycol, 5,5-dihydroxymethyl-l,3-dioxane, xylylene glycol and pentaerythitol spiroglycol having an alkoxylation degree of for instance 1-20 alkoxy units / molecule. Yet further suitable embodiments of said diol include compounds such as bisphenol A and bisphenol F as well as alkoxylated, such as ethoxylated, propoxylated and/or butoxylat- ed, species thereof having an alkoxylation degree as previously said.

Embodiments of said triol can be exemplified by, but not limited to, glycerol, trime- thylolethane, trimethylolpropane, trimethylolbutane, xylylene triol (benzene trimethanol), caprolactone triols, to a said triol corresponding polycarbonate triols as well as alkoxylated, such as ethoxylated, propoxylated and/or butoxylated, glycerol, trimethylolethane, trimethylolpropane, trimethylolbutane or xylylene triol (benzene trimethanol) having an alkoxylation degree of for instance 1-20 alkoxy units / molecule.

Embodiments of said tetrol can be exemplified by, but not limited to, pentaerythritol, di- trimethylolethane, di-trimethylolpropane, ditrimethylolbutane, caprolactone tetrols, to a said tetrol corresponding polycarbonate tetrols as well as by alkoxylated, such as ethoxylated, propoxylated and/or butoxylated, pentaerythritol, di-trimethylolethane, di-trimethylolpropane and ditrimethylolbutane having an alkoxylation degree of for instance 1-20 alkoxy units / molecule.

Embodiments of said pentol can be exemplified by, but not limited to, anhydroenneaheptitol, xylitol, caprolactone pentols, to a said pentol corresponding polycarbonate pentols as well as alkoxylated, such as ethoxylated, propoxylated and/or butoxylated, anhydroenneaheptitol or xylitol having an alkoxylation degree of for instance 1-20 alkoxy units / molecule.

Embodiments of said hexol can be exemplified by, but not limited to, di-pentaerythritol, sorbitol, mannitol, caprolactone hexols, to a said hexol corresponding polycarbonate hexols as well as alkoxylated, such as ethoxylated, propoxylated and/or butoxylated, dipentaerythritol, sorbitol or mannitol having an alkoxylation degree of for instance 1-20 alkoxy units / molecule.

In embodiments of the present invention, said composition suitably and additionally comprises at least one epoxy (meth)acrylate, amine modified epoxy (meth)acrylate, urethane (meth)acrylate, bisphenol A (meth)acrylate, polyester (meth)acrylate, polyether (mefh)acrylate, amine modified polyether (meth)acrylate, acid functional (meth)acrylate, lauryl(mefh)acrylate, nonylphenol (meth)acrylate, alkoxylated, such as ethoxylated, propoxylated and/or butoxylated, nonylphenol (meth)acrylate, oxetane(meth)acrylate, cyano(meth)acrylate and/or tetrahydro- furfuryl (meth)acrylate. In further embodiment of the present invention, said composition may suitably and additionally comprise at least one vinyl monomer, oligomer or polymer such as, but not limited to vi- nylpyrrolidones, polyolefins, including polyethylenes, polypropylenes and polybutadienes, sty- renes including polystyrenes, vinyl halides, including polyvinyl chlorides and fluorides, vinyl acetates including polyvinyl acetates, vinyl alcohols including polyvinyl alcohols, and acrylo- nitriles including polyacrylonitriles.

In yet further embodiments of the present invention, said composition is a UV, IR and EB curable composition and can optionally and additionally comprise at least one matting agent, flow/levelling agent, rheology modifying agent, dye and/or pigment.

The composition of the present invention is in especially preferred embodiments a UV curable composition which additionally comprises at least one photoinitiator such as at least one free radical, cation and/or anion photoinitiator. Suitable photoinitiator can be exemplified by, but not limited to, sulphonium antimonates, such as triarylsulphonium hexaantimonate, sulphoni- um fluoroantimonates, sulphonium fluorophosphates, such as triarylsulphonium hexafluoro- phosphate, sulphonium nitrates, sulphonium triflates, iodonium fluorophophates, such as dimetyl-diphenyl iodonium hexafluorophosphate, hydroxy(cyclo)alkylaryl ketones, such as hy- droxycyclohexylphenyl ketones, metallocenes, such as ferrocenes, rhutenocennes and titano- cenes, ketoprofens, benzoin ethers, benzil ketals, benzophenones, acetophenones, aminoal- kylphenones, acylphosphine oxides, benzoephenones, thixantones, anthraquinones and/or camphorquinones .

In a further aspect, the present invention refers to the use of a composition as disclosed above in coatings, including haptic coatings, for wood, metal, plastics, textiles and paper, flexo and digital inks, 3D printing, graphic arts, adhesives, medical and dental applications and devices, absorbents, sanitary articles, packaging, electronic and electric applications and devices, and/or optical application and devices. In yet a further aspect, the present invention refers to the use of 2-hydroxy-3-butenoic acid or methyl or ethyl vinyl glycolate acid as reactive diluent in a radiation curing composition.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilise the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative and not limitative in any way whatsoever. In the following Examples shows that the 2-hydroxy-3-butenoic acid ester methyl vinyl glycolate, unexpectedly and despite having only one carbon-carbon double, UV cures and Example 2 shows that said ester in combination with a second UV curable compound give excellent curing and excellent film properties.

Example 1

96 parts by weight of methyl vinyl glycolate was mixed with 4 parts by weight of the photoin- itiator Irgacure® 500 (Ciba Specialty Chemicals) and UV cured 30 * 5 m/min H-bulb set at 100% with a filmthickness of 40 μιη on glass panels.

The following harness properties were obtained:

Konig hardness, 1 hr. 70 konig sees.

Konig hardness, 24 hrs. 74 konig sees.

Konig hardness, 1 week 62 konig sees.

Used equipment gave UV dose J/cm ² H-bulb set at 100%:

UV-A UV-B UV-C UV-V

26.7 23.46 5.25 28.38

Example 2

50 parts by weight of methyl vinyl glycolate was mixed with 46 parts by weight of hexanediol diacrylate and 4 parts by weight of the photoinitiator Irgacure^ 500 (Ciba Specialty Chemicals) and UV cured 20 * 5 m/min H-bulb set at 100% with a filmthickness of 40 μηι on glass panels.

The following hardness properties were obtained:

Konig hardness, 1 hr. 170 konig sees.

Konig hardness, 24 hrs. 181 konig sees.

Konig hardness, 1 week 200 konig sees.

Used equipment gave UV dose, J/cm ² H-bulb set at 100%:

UV-A UV-B UV-C UV-V

17.8 15.64 3.7 18.92