HK1091907B - Radiation curable compositions - Google Patents

Description

Radiation curable compositions

Background

In the automotive refinish applications, minor repairs need to be performed quickly and at room temperature, UV technology ensures a significant increase in automotive output in body shops.

U.S. Pat. No. 5,684,081 describes a radiation curable aqueous dispersion, but this reference is silent as to the wavelength of the radiation used, the use of UV radiation curable compositions having very low UV-B content and substantially no UV-C content is also known (see, for example, U.S. patent application publication 2003/0059555 and U.S. patent 6,538,044.) the compositions described in the '044 patent are non-aqueous and are not based on urethane chemistry aromatic lacquer coatings the' 555 publication describes solvent-based compositions for use as primers. Wherein the composition is non-aqueous and requires wiping the coating with an organic solvent after exposure to UV radiation and prior to sanding the coated part.

U.S. Pat. No. 6,559,225 describes an aqueous polyurethane dispersion for paints and coatings. The '225 patent does not describe UV curing and suggests that the dispersion may be combined with a radiation curable binder (column 5, lines 17-20.) U.S. patent 6,579,932 describes an aqueous coating composition that is a mixture of a polyurethane/acrylate hybrid dispersion and a polyurethane resin having oxidized anhydrous groups the' 932 patent does not describe UV curing.

Aqueous radiation curable dispersions are also known (see e.g. us patents 5,362,773, 6,011,078, 6,479,577, 6,521,702 and 6,541,536).

Non-aqueous radiation curable compositions are also known. WO01/74499 describes a primer composition containing one or more compounds containing two or more ethylenically unsaturated polymerizable groups per molecule, epoxy acrylates, urethane acrylates and unsaturated polyesters, wherein the composition also requires a significant amount of relatively low molecular weight materials (such as ethylhexyl acrylate and isobornyl methacrylate). The' 499 publication suggests that wherein the composition can use UV-B: UV-A ratio of 1: UV lamps of 1 or less and substantially no UV-C content cure by UV radiation. Similar compositions are described in published U.S. patent applications US2003/0045598 and US2003/045596, and U.S. patents 4,937,173, 5,013,631, 5,213,875 and 6,509,389.

Radiation curable urethane acrylates are also described in U.S. Pat. Nos. 4,380,604, 6,232,360, 6,753,394, and 6,790,485, and finally, radiation curable epoxy acrylates are described in U.S. Pat. Nos. 5,726,255, 5,756,829, 6,359,082, and Re37,448.

It has now been found that compositions can be cured with radiation having a wavelength of at least 300nm and preferably from 320nm to 450nm.

Disclosure of Invention

More particularly, the present invention relates to a composition that is curable by radiation having a wavelength of 300nm or longer, preferably a wavelength of about 320nm to about 450nm.

The composition of the invention is a non-aqueous composition, which is free of ethylenically unsaturated monomers and comprises

A) From about 1 to about 99 weight percent, preferably from about 10 to about 90 weight percent, and most preferably from about 25 to about 75 weight percent of an unsaturated (meth) acrylate polymer or oligomer selected from the group consisting of:

a) an unsaturated urethane (meth) acrylate polymer or oligomer having an isocyanate group content of 1% by weight or less and prepared by reacting:

ai) one or more organic polyisocyanates, and

aii) unsaturated (meth) acrylates selected from

1)0 to 100% by weight of an unsaturated polyether (meth) acrylate polyol having an OH number of from about 30 to about 500 (preferably from about 100 to about 400 and most preferably from about 200 to about 300) and prepared by reacting a polyether di or polyol with acrylic acid and/or methacrylic acid, and

2)0 toAbout 100% by weight of a mono-, di-, tri-or polyhydroxy-C₁-C₁₀-alkyl or C₆-C₁₀Aryl (meth) acrylates, wherein the weight percentages of components aii)1) and aii)2) are based on the total weight of components aii)1) and aii)2) and add up to 100%,

the equivalent ratio of isocyanate to hydroxyl groups is about 0.95: 1 to about 1: 0.95 (preferably about 1: 1),

b) an unsaturated polyether (meth) acrylate polyol having an OH number of from about 30 to about 100 (preferably from about 30 to about 70 and most preferably from about 35 to about 65) and prepared by reacting a polyether di or polyol with acrylic and/or methacrylic acid, and

c) a mixture of these with a further component,

B) from about 1 to about 99 weight percent, preferably from about 10 to about 90 weight percent, and most preferably from about 25 to about 75 weight percent of an unsaturated epoxy (meth) acrylate that is substantially free of epoxy groups and is prepared by reacting:

bi) one or more organic compounds containing at least one epoxy group and having a number average molecular weight of from about 130 to about 1000,

bii)1.3 to 3.0 carboxyl equivalent of an organic dicarboxylic acid or anhydride having a number average molecular weight of about 98 to about 166,

biii)1 hydroxyl equivalent of a hydroxyl containing reaction product having a carboxyl to hydroxyl equivalent ratio of 0.6: 1 to 0.95: 1 the following components:

1) (meth) acrylic acid and

2) a tri-or tetrahydroxyether alcohol having a number average molecular weight of about 180 to about 1000 and containing at least two ethylene oxide and/or propylene oxide units as ether moieties,

the ratio of the reactive equivalents of components bii) to biii) to the epoxy equivalents of component bi) is at least about 1: 1,

C) from about 0.1 to about 10 wt%, preferably from about 0.5 to about 6 wt%, and most preferably from about 1 to about 4 wt% of one or more photoinitiators, wherein the wt% of component C) is based on the total weight of components A) and B), and wherein the percentages of components A) and B) total 100%, and

D)0 to about 90% by weight of a solvent or solvent mixture, wherein the% by weight of component D) is based on the total combined amount of components A) and B).

Component A is an unsaturated (meth) acrylate polymer or oligomer broadly selected from the group consisting of urethane (meth) acrylates, polyether (meth) acrylates, and mixtures thereof useful urethane (meth) acrylates are described in U.S. Pat. Nos. 4,380,604 and 6,753,394, the disclosures of which are incorporated herein by reference, and useful epoxy acrylates are described in U.S. Pat. Nos. 5,726,255 and Re37,448, the disclosures of which are incorporated herein by reference.

The phrase "ethylenically unsaturated monomer" as used herein means a relatively low molecular weight compound having a number average molecular weight of less than about 250.

Component A)

Component a) is an unsaturated (meth) acrylate polymer or oligomer selected from:

a) an unsaturated urethane (meth) acrylate polymer or oligomer having an isocyanate group content of 1% by weight or less and prepared by reacting:

ai) one or more organic polyisocyanates, and

aii) an unsaturated (meth) acrylate selected from:

1)0 to 100% by weight of an unsaturated polyether (meth) acrylate polyol having an OH number of from about 30 to about 500 (preferably from about 100 to about 400 and most preferably from about 200 to about 300) and prepared by reacting a polyether di or polyol with acrylic acid and/or methacrylic acid, and

2)0 to about 100% by weight of a mono-, di-, tri-or polyhydroxy-C₁-C₁₀-alkyl or C₆-C₁₀Aryl (meth) acrylates, wherein the weight percentages of components aii)1) and aii)2) are based on the total weight of components aii)1) and aii)2) and add up to 100%,

the equivalent ratio of isocyanate to hydroxyl groups is about 0.95: 1 to about 1: 0.95,

b) an unsaturated polyether (meth) acrylate polyol having an OH number of from about 30 to about 100 (preferably from about 30 to about 70 and most preferably from about 35 to about 65) and prepared by reacting a polyether di or polyol with acrylic and/or methacrylic acid, and

c) mixtures thereof.

As mentioned above, useful urethane (meth) acrylates (A) a)) are described in U.S. Pat. Nos. 4,380,604 and 6,753,394, such urethane (meth) acrylates are generally prepared by reacting more than one polyisocyanate with a hydroxyl group-containing unsaturated (meth) acrylate.

Suitable polyisocyanates include organic polyisocyanates having aliphatically, cycloaliphatically and/or aromatically bonded isocyanate groups and generally having a molecular weight of from about 144 to about 1000, more preferably from about 168 to about 300. Suitable examples include butylidene diisocyanate, hexamethylene diisocyanate (HTI), isophorone diisocyanate (IPDI), 3(4) -isocyanatomethyl-methylcyclohexyl isocyanate (IMCI), trimethylhexamethylene diisocyanate (2, 2,4 and/or 2,4, 4-trimethyl-hexamethylene diisocyanate), the isomeric bis (4, 4' -isocyanato-cyclohexyl) methane (H)₁₂MDI), isomeric bis (isocyanatomethyl) -methylcyclohexanes, isocyanatomethyl-1, 8-octane diisocyanate, 1, 4-cyclohexylene diisocyanate, 1, 4-phenylene diisocyanate, 2, 4-and/or 2, 6-Tolylene Diisocyanate (TDI), 1, 5-naphthylene diisocyanate, 2,4 ' -and/or 4, 4 ' -diphenylmethane diisocyanate (MDI), triphenylmethane-4, 4 ' -triisocyanate or their mixtures with urethanes, isocyanurates, allophanates, biurets, uretdiones, iminooxanes or their mixturesThe production of derivatives of the diazinedione structure and/or mixtures thereof and mixtures of aliphatic and aromatic diisocyanates and/or polyisocyanates is known and described, for example, in U.S. Pat. Nos. 3,124,605, 3,183,112, 3,919,218 and 4,324,879 and in European patent 798299.

Preferably HDI, IPDI, TDI, H are used₁₂MDI and/or polyisocyanates containing isocyanurate groups which are obtained by trimerization of HDI, TDI or IPDI. Particularly preferred are HDI and IPDI and mixtures thereof.

In the preparation of unsaturated urethane (meth) acrylates, the isocyanate to OH equivalent ratio is about 0.95: 1 to about 1: 0.95 (more preferably about 1: 1) reacting a polyisocyanate with i) an unsaturated polyether (meth) acrylate having an OH number of from about 30 to about 300, ii) a mono-, di-, tri-or polyhydroxy C₁To C₁₀-alkyl or C₆To C₁₀Aryl (meth) acrylates, or iii) mixtures thereof. The resulting unsaturated polyurethane (meth) acrylates have an isocyanate group content of less than 1% by weight.

Suitable polyether polyols are of the type known in the polyurethane art and are typically prepared by reacting a suitable starter molecule (e.g., ethylene glycol, propylene glycol, butanol, glycerol, trimethylolpropane, hexanediol, pentaerythritol, etc.) with ethylene oxide, propylene oxide, or mixtures thereof. When the unsaturated (meth) acrylate is used to prepare the unsaturated polyurethane (meth) acrylate, the polyether is selected so that the resulting (meth) acrylate has a desired OH number, and the components are reacted in amounts so that the resulting unsaturated polyether (meth) acrylate has an OH number of from about 30 to about 500, preferably from about 100 to about 400, and most preferably from about 200 to about 300. in the case where the unsaturated (meth) acrylate is used as part or all of component A), the polyether is selected so that the resulting (meth) acrylate has a desired OH number, and the polyether and acrylic (and/or methacrylic) acid are reacted in amounts so that the resulting unsaturated polyether (meth) acrylate has an OH number of from about 30 to about 100, preferably from about 100 to about 400, and most preferably from about 200 to about 300.

Useful mono-, di-, tri-or polyhydroxy C₁To C₁₀-alkyl or C₆To C₁₀Aryl (meth) acrylates are also known in the polyurethane art. Such materials are prepared by reacting relatively low molecular weight diols, triols and polyols (e.g., ethylene glycol, propylene glycol, butanol, glycerol, trimethylolpropane, hexanediol, pentaerythritol, etc.) with acrylic acid and/or methacrylic acid in amounts such that the resulting product contains one or more hydroxyl groups.

Component B)

Component B) is an unsaturated epoxy (meth) acrylate substantially free of epoxy groups and is prepared by reacting

bi) one or more organic compounds containing at least one epoxy group and having a number average molecular weight of from about 130 to about 1000,

bii)1.3 to 3.0 (preferably 1.8 to 2.2 and most preferably 1.9 to 2.1) carboxyl equivalent weight of an organic dicarboxylic acid or anhydride having a number average molecular weight of about 98 to about 166,

biii)1 hydroxyl equivalent of a hydroxyl containing reaction product having a carboxyl to hydroxyl equivalent ratio of 0.6: 1 to 0.95: 1 the following components:

1) (meth) acrylic acid and

2) a tri-or tetrahydroxyether alcohol having a number average molecular weight of about 180 to about 1000 and containing at least two ethylene oxide and/or propylene oxide units as ether moieties,

the ratio of the reactive equivalents of components bii) to biii) to the epoxy equivalents of component bi) is at least about 1: 1.

as noted above, useful unsaturated epoxy (meth) acrylates are described in U.S. Pat. nos. 5,726,255, 6,359,082 and RE37,448.

The epoxy (meth) acrylates used in the present invention are prepared by reacting an organic compound containing epoxy groups with bii)1.3 to 3.0 carboxyl equivalent of an organic dicarboxylic acid or anhydride having a molecular weight of about 98 to about 166 and biii)1 hydroxyl equivalent of the reaction product containing OH groups in a COOH/OH equivalent ratio of 0.6: 1 to 0.95: 1) (meth) acrylic acid and 2) a tri-or tetrahydroxyether alcohol having a number average molecular weight of 180 to 1000 and containing at least two ethylene oxide and/or propylene oxide units as ether moieties.

In the context of the present invention, "compound having an epoxy group" means a number average molecular weight (M)_n) "epoxy equivalent" means the grams of epoxy compound containing one mole of epoxy groups per molecule of an organic compound that is from about 130 to about 1000 and contains an average of at least one (preferably from 1.5 to 6, more preferably from 1.5 to 2) epoxy groups per molecule.

Examples include polyglycidyl ethers of polyhydric phenols such as catechol, resorcinol, hydroquinone, 4 ' -dihydroxydiphenylmethane, 2-bis- (4-hydroxyphenyl) -propane (bisphenol A), 4 ' -dihydroxydiphenylcyclohexane, 4 ' -dihydroxy-diphenylsulfone, tris- (4-hydroxyphenyl) -methane, and novolaks (i.e., the reaction product of a mono-or polyhydric phenol with an aldehyde, particularly formaldehyde, in the presence of an acid catalyst).

Also suitable are glycidyl ethers of monohydric alcohols such as n-butanol or 2-ethylhexanol; glycidyl ethers of polyhydric alcohols such as butane 1, 4-diol, butene 1, 4-diol, hexane 1, 6-diol, glycerol, trimethylolpropane, pentaerythritol and polyethylene glycol; triglycidyl isocyanurate; polyglycidyl sulfides of polyhydroxy thiols such as dimercaptomethyl benzene; a monocarboxylic acid, such as a glycidyl ester of a branched alkane carboxylic acid (versatic acid); and glycidyl esters of polyvalent aromatic, aliphatic and alicyclic carboxylic acids, such as diglycidyl phthalate, diglycidyl isophthalate, diglycidyl terephthalate, diglycidyl tetrahydrophthalate, diglycidyl adipate and diglycidyl hexahydrophthalate.

The dicarboxylic acid or dicarboxylic anhydride (bii) is selected from saturated or unsaturated aliphatic dicarboxylic acids containing from 4 to 10 carbon atoms, such as fumaric acid, maleic acid, succinic acid, adipic acid, sebacic acid, itaconic acid and/or the corresponding anhydrides thereof; alicyclic dicarboxylic acids or dicarboxylic anhydrides having 8 to 10 carbon atoms, such as tetrahydrophthalic acid, hexahydrophthalic acid, norbornene dicarboxylic acids and/or anhydrides thereof; and aromatic dicarboxylic acids having 8 carbon atoms or anhydrides thereof, such as phthalic acid, phthalic anhydride, isophthalic acid and terephthalic acid.

The dicarboxylic acid anhydrides (bii) are selected from anhydrides of saturated aromatic or unsaturated (cyclo) aliphatic dicarboxylic acids having from 4 to 9 carbon atoms, such as maleic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid or norbornene dicarboxylic acid, one carboxylic anhydride group corresponds to two carboxyl groups when calculating the ratio of carboxyl equivalents (component biii) to hydroxyl equivalents (component bii).

Component biii) is selected from the group consisting of the OH-group-containing reaction products of (meth) acrylic acid with tri-or tetrahydroxyether alcohols having a number-average molecular weight (determined by end group analysis) of from 180 to 1000 and containing at least two ethylene oxide and/or propylene oxide units as ether moieties, these reaction products having a COOH/OH equivalent ratio of 0.6: 1 to 0.95: 1, preferably 0.65: 1 to 0.90: the preferred starter molecules are tri-or tetrahydric alcohols that correspond to ether alcohols without ether groups examples include glycerol, trimethylolpropane, trimethylolethane, pentaerythritol and mixtures thereof the ether alcohols preferably have a degree of alkoxylation of from 2 to 20, more preferably from 2 to 15.

The reaction between components 1) and 2) can take place according to known methods, for example by azeotropic esterification of (meth) acrylic acid with ether alcohols the reaction of the epoxy compound with compounds bii) and biii) can also be carried out in one step, for example according to the methods of DE-OS 2,429,527 and DE-A2,534,012 (corresponding to U.S. Pat. Nos. 4,253,198 and 4,081,492, respectively, both of which are incorporated herein by reference), optionally in the presence of solvents. The reaction is usually carried out in the presence of about 0.01 to 3% by weight, based on the epoxy compound, of a catalyst such as a tertiary amine, a quaternary ammonium salt, an alkali metal hydroxide, an alkali metal salt of an organic carboxylic acid, a thiol, a dialkyl sulfide, a sulfonium or phosphonium compound and a phosphine. It is particularly preferred to use quaternary ammonium salts, such as triethylbenzylammonium chloride, the reaction taking place at from 20 to 120 c, preferably from 40 to 90 c.

The epoxy (meth) acrylate may optionally be modified with a basic nitrogen compound in an amount sufficient to provide up to 0.3NH equivalents per epoxide equivalent the modification reaction may be carried out before or after the reaction of the epoxy compound with components bii) and biii) suitable basic nitrogen compounds include ammonia, (cyclo) aliphatic primary or secondary mono-or polyamines, preferably having a molecular weight of from 31 to 300. Examples of primary amines include mono-and diamines such as methylamine, N-butylamine, N-hexylamine, 2-ethylhexylamine, cyclohexylamine, ethanolamine, benzylamine, ethylenediamine, the isomeric diaminobutanes, the isomeric diaminohexanes, and 1, 4-diaminocyclohexane examples of secondary amines include dimethylamine, diethylamine, diethanolamine, diisopropanolamine, N-methylethanolamine, and N-cyclohexylisopropylamine.

The reaction of the epoxide group with the nitrogen compound may optionally be carried out in the presence of a solvent as described previously. The reaction is preferably carried out in the absence of a solvent. The reaction temperature is from 20 to 120 ℃ and preferably from 40 to 90 ℃.

The amount of starting compound is chosen such that the reaction results in substantially complete conversion of the epoxide groups initially present.

In order to prevent undesired premature polymerization of the polymerizable reaction products according to the invention, it is advisable to add polymerization inhibitors or antioxidants, such as phenols and phenol derivatives, preferably sterically hindered phenols, in amounts of from 0.001 to 0.2% by weight, based on the total reaction mixture including auxiliaries and additives, during the preparation. Other suitable stabilizers are described in "Methodender organischen Chemie" (Houben-Weyl), 4 th edition, volume XIV/1, 433-452,756, Georg Thieme Verlag, Stuttgart, 1961 and include 2, 6-di-tert-butyl-p-cresol, hydroquinone monomethyl ether and/or phenothiazine.

Component C

Component C), i.e., the photoinitiator, can be essentially any photoinitiator various photoinitiators can be used in the radiation-curable compositions of the present invention. Commonly used photoinitiators are of the type that generate free radicals when exposed to radiant energy. Suitable photoinitiators include, for example, aromatic ketone compounds such as benzophenone, alkylbenzophenones, Michler's ketone, anthrone, and halobenzophenones additional suitable compounds include, for example, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, benzoyl formate, anthraquinone and its derivatives, benzil ketals, and hydroxyalkylphenyl ketones exemplary additional suitable photoinitiators include 2, 2-diethoxyacetophenone; 2-or 3-or 4-bromoacetophenone; 3-or 4-allyl-acetophenone; 2-acetonaphthone; benzaldehyde; benzoin; an alkyl benzoin ether; benzophenone; benzoquinone; 1-chloroanthraquinone; p-diacetylbenzene; 9, 10-dibromoanthracene; 9, 10-dichloroanthracene; 4, 4-dichlorobenzophenone; a thioxanthone; isopropyl thioxanthone; methyl thioxanthone; α, α, α -trichloro-p-tert-butylacetophenone; 4-methoxybenzophenone; 3-chloro-8-nonyl xanthone; 3-iodo-7-methoxyxanthone; carbazole; 4-chloro-4' -benzylbenzophenone; a fluoroalkene; a fluoroketone; 1, 4-naphthyl phenyl ketone; 1, 3-pentanedione; 2, 2-di-sec-butoxyacetophenone; dimethoxyphenylacetophenone; propiophenone; isopropyl thioxanthone; chlorothioxanthone; xanthone; maleimide and derivatives thereof; and mixtures thereof. There are several suitable photoinitiators available from Ciba, including Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone), Irgacure819 (bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide), Irgacure 1850 (50/50 mixture of bis (2, 6-dimethoxybenzoyl) -2, 4, 4-trimethylpentyl-phosphine oxide and 1-hydroxy-cyclohexyl-phenyl-ketone), Irgacure 1700 (25/75 mixture of bis (2, 6-dimethoxybenzoyl) -2, 4, 4-trimethylpentyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-1-propanone), Irgacure 907 (2-methyl-1 [4- (methylthio) phenyl ] -2-morpholine-1-propanone) Darocur MBF (methyl benzoylformate), Irgacure 2020 photoinitiator blend (20 wt% of phenyl bis (2, 3, 6-trimethylbenzoyl) phosphine oxide and 80 wt% of 2-hydroxy-2-methyl-1-phenyl-1-propanone) and Darocur 4265 (50/50 mixture of bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one). The above list is merely exemplary and is not meant to exclude any suitable photoinitiators those of ordinary skill in the art are familiar with the effective use of photoinitiators and typically do not exceed about 10% by weight of the radiation curable coating composition.

Photoactivators are well known in the art and it is known without further description what compound they are and the effective concentration thereof. However, exemplary compounds that are suitable photoactivators may include methylamine, tributylamine, methyldiethanolamine, 2-aminoethylethanolamine, allylamine, cyclohexylamine, cyclopentylamine, diphenylamine, xylidine, trimethylbenzylamine, tribenzylamine, N-cyclohexylethylenimine, piperidine, N-methylpiperazine, 2-dimethyl-1, 3-bis (3-N-morpholinyl) -propionyloxypropane, and mixtures thereof.

Curing can also be carried out in the presence of free-radical-generating compounds, such as (hydro) peroxides, optionally in the presence of accelerators, and cationically in the presence of peracids, such as phenyl sulfonium metal salts.

Component D

The compositions of the present invention may also contain one or more solvents in an amount of from 0 to about 90 weight percent, where the weight percent is based on the total combined amount of components A) and B). Useful solvents include C₅-C₈Aliphatic and cycloaliphatic compounds, fluorinated and/or chlorinated hydrocarbons, aliphatic esters, aliphatic ethers and ketones, and also known aromatic hydrocarbon solvents. Specific examples of useful solvents include ethyl acetate, butyl acetate, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, isopropyl alcohol, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and solvent naphtha.

Other additives

In addition, when the shape of the article to be coated is one in which the coated portions cannot be exposed to radiation, materials that crosslink through carboxyl groups, hydroxyl groups, amino groups, or moisture may be added. When used, such crosslinking agents should be used in amounts of 0.1 to 35 weight percent based on the total weight of components A) and B).

Application and curing

Typically, components a) and B) are first mixed with each other, and then component C) and any further additives are added thereto. The compositions of the present invention can be applied to a wide variety of substrates by spraying, rolling, knife coating, casting, brushing, dipping, puttying or doctoring. Any solvent present may then be flashed off in a conventional oven at a temperature of from about 20 to about 110 c, preferably from about 35 to about 60 c, for a period of from about 1 to about 10 minutes, preferably from about 4 to 8 minutes. The solvent may also be flashed off using a radiation source such as infrared or microwave.

Once the solvent has been baked off, the coated substrate is subjected to ultraviolet radiation having a wavelength of at least 300nm, preferably a wavelength of from about 320 to about 450nm the distance between the surface and the radiation source is dependent on the intensity of the light source and should generally be no more than four feet the duration of the irradiation of the coated substrate is dependent on the intensity and wavelength of the radiation, the distance to the radiation source, the amount of solvent in the formulation, the temperature and humidity of the curing environment, but generally should be less than 15 minutes and can be as short as 0.1 second.

Cured coatings are known for their sandability.

The radiation may be provided by any suitable light source, such as a UV lamp with or having reduced infrared emission or a UV lamp equipped with a filter to eliminate infrared emission or so-called LEDs (light emitting devices) emitting radiation at said wavelength. Particularly useful commercially available devices include: panacol UV H-254 lamp (available from Panacol-Elosol GmbH) -a 250W ozone-free iron-doped metal halide lamp with a spectral wavelength of 320 to 450 nm; panacol UVF-450(320nm to 450nm, depending on the black, blue or clear filter used); honle UVA HAND 250 CUL (available from Honle UV America Inc) -emission maximum intensity UVA range of about 320 to 390 nm; PMP250 watt metal halide lamps (available from Pro Motor Car Products Inc); Cure-Tek UVA-400 (from H)&S Autoshot) having a 400 watt metal halide bulb and the lamp assembly may be equipped with different filters, such as blue, light blue or clear filters to control/eliminate infrared radiation from the lamp light source); Con-Trol-Cure Scarab-250 UV-A workshop Lamp System (available from UV Process Supply)Inc-a 250W iron-doped metal halide lamp with a spectral output wavelength of 320 to 450 nm); Con-Trol-Cure-UV LED Cure-All 415 (available from UV Process Supply Inc. -with a spectral wavelength of 415nm, having a working wattage range of 2.5 to 7.95W); Con-Trol-Cure-UV LED Cure-All 390 (available from UV Process supply Inc. -with a spectral wavelength of 390nm, having a working wattage range of 2.76 to 9.28W); UV H253UV lamp (available from UV Light Technologies-the cell contains a 250W iron-doped metal halide lamp equipped with a black glass filter, producing a spectral wavelength between 300 and 400 nm); radius RX10 modulus cure using a solid state high intensity UV light source from phoseon technology; low intensity microwave UV System model QUANT-18/36 (available from Quantum Technologies-UV intensity range: 3-30 mW/cm)²(ii) a UV spectral range: 330-390 nm); WorkLED (from Inretechtechnologists, using 400nm LED array); flashlight MC with 20 x LED adapter (available from Inretech Technologies, using 400nm LEDs); and Phillips TL03 lamps with radiation output above 380 nm.

The following examples are intended to illustrate the invention, but not to limit its scope unless otherwise indicated, all percentages and parts are by weight.

In the examples, the following materials were used:

TiO₂： TiO₂r-960 from DuPont

Tronox-A: untreated anatase pigment, available from Kerr-McGee Pigments GmbH & Co.

Epon 828: aromatic epoxy resins based on bisphenol A and epichlorohydrin, epoxy equivalent weight 190, available from Resolution Performance Products

Desmodur N3600: low viscosity hexamethylene diisocyanate trimer available from Bayer Materialscience LLC

Barytes 1: sparmite No.1 barytes-extender pigment barium sulfate, available from Elementis Pigments, Inc.

CC: calcium carbonate, Vicron15-15, available from Whittaker, Clark & Daniels, Inc.

T399: talc 399 from Whittaker, Clark & Daniels, Inc.

B318: iron oxide pigment supplied as Bayferrox 318M, available from Bayer Chemical Corporation

CD 9052: trifunctional acid ester adhesion promoter, available from Sartomer Inc.

IRG 2020: photoinitiator blend { 20% by weight of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (I819) and 80% by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone (D1173) }, available from Ciba Specialty Chemicals

IRG 819: irgacure819 photoinitiator, { phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide }, available from Ciba Specialty Chemicals

Unsaturated acrylate polymer a 1:

step 1: 86 parts of a polyether polyol having a hydroxyl number of 250 (trimethylolpropane ethoxylated 12 times), 18.7 parts of acrylic acid, 1.5 parts of p-toluenesulfonic acid, 0.3 part of p-methoxyphenol and 0.02 part of 2, 5-di-tert-butylhydroquinone are dissolved in cyclohexane to form a 70% solution and heated to reflux temperature with stirring and by means of air.

Step 2: 70 parts of the unsaturated polyether acrylate polyol prepared using step 1, 10.5 parts of hydroxyethyl acrylate, 20 parts of isophorone diisocyanate and 0.01 part of dibutyltin dilaurate and 0.01 part of p-methoxyphenol (polymerization inhibitor) were mixed together, the reaction mixture was stirred at 80 ℃ and the NCO groups were monitored using infrared spectroscopy. When the isocyanate group was completely consumed, the resultant unsaturated urethane acrylate resin had a viscosity of about 7,000mpa.s measured at 23 ℃ and a C ═ C content of 2.7mol/kg.

Unsaturated acrylate Polymer A2: 1 mole of a polyether polyol having a hydroxyl number of 550 (trimethylolpropane ethoxylated 4 times) was reacted with 2.6 moles of acrylic acid in the presence of 1.5 parts of p-toluenesulfonic acid, 0.3 part of p-methoxyphenol and 0.02 part of 2, 5-di-tert-butylhydroquinone in 70% solution of cyclohexane with stirring and heating to reflux temperature by air, the mixture was maintained under vigorous reflux for about 4 hours until the acid number of the solid reached less than 5mg KOH/g, after cooling the mixture to 50 ℃ vacuum was applied and cyclohexane was distilled off together with the water formed, the hydroxyl number of the polyether acrylate polyol obtained was 50.

Unsaturated acrylate Polymer A3: 90.4 parts of an unsaturated polyether acrylate polyol having a hydroxyl number of 50, 9.6 parts of isophorone diisocyanate were mixed together with 0.01 part of dibutyltin dilaurate and 0.01 part of p-methoxyphenol (polymerization inhibitor). the reaction mixture was stirred at 80 ℃ and the NCO groups were monitored using infrared spectroscopyThe alkenoic acid ester resin had a viscosity of about 800mpa.s measured at 23 ℃ and a C ═ C content of 5.3mol/kg.

Unsaturated acrylate Polymer A4: 62.1 parts Desmodur N3600, 22.8 parts hydroxyethyl acrylate, 11 parts hydroxypropyl acrylate, 4.1 parts 2-ethyl-1, 3-hexanediol were mixed together with 0.05 parts dibutyltin dilaurate and 0.1 part p-methoxyphenol (polymerization inhibitor) and 25 parts butyl acetate. The reaction mixture was stirred at 80 ℃ and the NCO groups were monitored using infrared spectroscopy. When the isocyanate groups were completely consumed, the resulting unsaturated urethane acrylate resin had a viscosity of about 6800cPs measured at 23 ℃.

Unsaturated epoxy acrylate B: 74 parts of unsaturated acrylate polymer A2, 7.1 parts of maleic anhydride, 16.6 parts of Epon828 with an epoxy equivalent weight of 190, 2.5 parts of diethanolamine, with 0.5% of triethylbenzylammonium chloride (epoxy acid catalyst) and 0.01 part of p-methoxyphenol (polymerization inhibitor) were mixed together, the mixture was heated to 80 ℃ with stirring and by means of air, the mixture was maintained at this temperature until the acid number of the solid had reached<5mg KOH/g. the formed 100% solids unsaturated epoxy acrylate resin has a viscosity of about 8,000mpa.s measured at 23 ℃ and a C-C content of 5mol/kg.

Example 1：

50 parts by weight of an unsaturated acrylate polymer A1, 50 parts by weight of an unsaturated epoxy acrylate B and 7.8 parts by weight of IRG819 are thoroughly mixed with one another, 3.4 parts by weight of TiO are then added with constant stirring₂41.1 parts by weight of CC, 59 parts by weight of extender pigment T399 and 0.58 part by weight of B318M were slowly added to the resin mixture. The prepared solvent-free formulation was left overnight to degas. The formulation was then applied to a cold rolled steel substrate at a wet film thickness of 3 mils using a squeegee or paint blade or using a puttying knife.

The panels were cured under a low intensity UV-A light source (Cure-Tek UVA-400 from H & S Autoshot) at a distance of 10 inches for 2 minutes to provide a tack free surface having a dry film thickness of 1.6 to 2.0 mils. The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing.

Example 2：

50 parts by weight of the unsaturated acrylate polymer A1, 50 parts by weight of the unsaturated epoxy acrylate B and 7.8 parts by weight of IRG819 are mixed thoroughly with one another. Then, 3.4 parts by weight of TiO was added with continuous stirring₂41.1 parts by weight of CC, 59 parts by weight of extender pigment T399, 0.58 part by weight of B318M, 30 parts by weight of adhesion promoter CD9052 were slowly added to the resin mixture. The prepared solventless formulation (pigment/binder ratio 0.8) was left overnight to de-air then the formulation was applied to a cold rolled steel substrate at a wet film thickness of 3 mils using a squeegee or paint blade or using a puttying knife.

The panels were cured under a low intensity UV-A light source (Panacol UV H-254 lamp-250W metal halide lamp without ozone doped iron, spectral wavelength 320-450nm) at a distance of 3 inches for 2 minutes to provide a tack free surface having a dry film thickness of 1.6 to 2.0 mils the same formulation was similarly applied to the panels and exposed to a low intensity UV-A light source (Cure-TekUVA-400 from H & S Autoshot) at a distance of 10 inches for 2 minutes to provide a tack free surface. The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing. It exhibits excellent hiding power.

Example 3：

The same formulation used in example 2 was applied to a cold rolled steel substrate in the same manner, followed by the use of a Con-Trol-Cure-UV LED Cure-All 415 device or a Con-Trol-Cure-UV LED Cure-All^TM100 array (spectral wavelength 390nm) with wet coating exposed at 1/4 inchesFrom the radiation from the LED light source. A non-tacky surface with good solvent resistance was obtained. Details are shown in Table 1. the primer has excellent Adhesion to cold rolled steel as measured according to the cross-hatch Adhesion test (ASTM D3359-95 and General Motors GM 9071PTape Adhesion Tests). The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing.

Table 1: LED radiation curing colored primer

Test results	Formulation of example 1	MEK double rub
			Radiation source	Time/distance
415C-T-C	1 second/1/4 inches	>100
C-T-C390 array	2 minutes \6 inches	1

Test results	Formulation of example 1	MEK double rub
			”	2 minutes \5 inches	17
”	2 minutes \4 inches	>100

Example 4：

The same formulation used in example 2 was diluted using 60 parts of butyl acetate as solvent. The formulation was then applied to cold rolled steel substrates by spraying at a wet film thickness of 4 mils using a Binks Model #2001 air siphon gun (air pressure 38-40 psi). The sprayed panels were air dried at room temperature for 4 minutes and then cured under a low intensity UV-A light source (Panacol UV H-254 lamp-250W ozone-free iron-doped metal halide lamp with a spectral wavelength of 320-450nm) for 2 minutes at a distance of 3 inches to provide a tack-free surface with a dry film thickness of 1.2 to 1.5 mils the sprayed panels were also exposed under a low intensity UV-A light source (Cure-Tek UVA-400 from H & SAutoshot) for a distance of 10 inches for 2 minutes to provide a dry film thickness of 1.2 to 1.5 mils the formulations had excellent Adhesion to cold rolled steel as measured by the cross-cut Adhesion test (ASTM D3359-95 and General Motors GM 9071P Tape adhesives Tests). The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing. It exhibits excellent hiding power.

The sprayed panels were prebaked in a 50 ℃ conventional hot air oven for 8 minutes and then exposed to radiation from an LED light source at a distance of 1/4 inches using a Con-Trol-Cure-UV LED Cure-All 415 device. A non-tacky surface with good solvent resistance was obtained in less than one minute. The primer has excellent Adhesion to cold rolled steel as measured by the cross-hatch Adhesion test (ASTM D3359-95 and General Motors GM 9071P Tape addition Tests). The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing.

Example 5：

50 parts by weight of an unsaturated acrylate polymer A1 and 50 parts by weight of an unsaturated epoxy acrylate B were mixed with one another and, with constant stirring, 5 parts by weight of T-TiO₂25 parts by weight of extender pigment T399, 132 parts by weight of Barytes # l, 1.0 part by weight of B318M, 10 parts by weight of adhesion promoter CD9052 were slowly added to the resin mixture 4.4 parts by weight aloneAmounts of IRG819 are dissolved in 58.45 parts by weight of butyl acetate and added to the dispersion mixture with thorough stirring. The solvent-based formulation prepared (pigment/binder ratio ═ 1.5) was left overnight to degas. The formulation was then applied to cold rolled steel substrates by spraying at a3 mil wet film thickness using a Binks Model #2001 air siphon gun (air pressure 38-40 psi).

The formulation was cured for 2 minutes at a distance of 3 inches under a low intensity UV-A light source (Panacol UV H-254 lamp-250W metal halide lamp without ozone-doped iron, radiation wavelength 320 and 450nm) to give a dry film thickness of 1. A non-tacky surface of 0 to 1.2 mils has excellent Adhesion to cold rolled steel as measured by the cross-cut Adhesion test (ASTM D3359-95 and general Motors GM 9071P Tape addition Tests.) the coating can be sanded with a #320 grit sandpaper and the substrate coated immediately after curing. It exhibits excellent hiding power.

Example 6：

50 parts by weight of the unsaturated acrylate polymer A1 and 50 parts by weight of the unsaturated epoxy acrylate B are thoroughly mixed with one another 6 parts by weight of IRG819 is slowly added to the resin mixture with constant stirring. The prepared formulation was left overnight to degas. The clear formulation was then applied by spraying to a wood substrate at a wet film thickness of 2 mils using a Binks model #2001 siphon air gun (air pressure 38-40 psi).

The coatings were cured under a low intensity Panacol UVA 400 lamp at a distance of 10 inches for 8 minutes to provide coatings with high pendulum hardness (dry film thickness of 0.9 to 1.2 mils) which had excellent Adhesion to wood substrates as measured by the cross-cut Adhesion test (ASTM D3359-95 and General Motors GM 9071P Tape Adhesion Tests.) the coatings could be sanded with #320 grit sandpaper and the top coated immediately after curing.

The block resistance test was performed as follows: the test was performed after 1 hour of curing the coating a1 "x 1" square piece of cheesecloth was placed on the surface of the coating and then a force of 2 pounds per square inch was applied to the cheesecloth by placing a weight thereon. After weighing for 24 hours the cheesecloth was removed and the surface of the coating was observed for any defects/changes.

Example 7：

50 parts by weight of unsaturated acrylate polymer A1 and 50 parts by weight of unsaturated epoxy acrylate B were thoroughly mixed with one another, 30 parts by weight of adhesion promoter CD9052 and 7.8 parts by weight of IRG819 were slowly added to the resin mixture with constant stirring, the prepared formulation was left overnight to de-air, and the clear formulation was then applied to a wood substrate by spraying at a wet film thickness of 2 mils using a Binks Model #2001 air-type siphon gun (air pressure 38-40 psi).

The coatings were cured under a low intensity Panacol UV H-254 lamp for 8 minutes at a distance of 10 inches to provide coatings with high pendulum hardnesses (dry film thicknesses of 0.9 to 1.2 mils). It has excellent Adhesion to wood substrates as measured by the cross-cut Adhesion test (ASTM D3359-95 and General Motors GM 9071P Tape addition Tests). The coating may be sanded with #320 grit sandpaper and the top coated immediately after curing. It has good solvent resistance and excellent blocking resistance.

Example 8：

The same formulation used in example 7 was applied to a cold rolled steel substrate in the same manner as described in example 7, followed by the use of Con-Trol-Cure-UV LED Cure-All^TM415 apparatus, exposed to radiation from an LED light source at a distance of 1/4 inches the details of the exposure time are shown in table 2. the resulting non-stick surface in each case has good solvent resistance the coating can be sanded with #320 grit sandpaper and the base coating applied just after curing.

Table 2: LED radiation-curable transparent encapsulant

Test results	Formulation of example 1	MEK double rub
			Radiation source	Time/distance
415C-T-C	1 second/1/4 inches	37
			“	3 seconds \1/4 inches	80
“	4 seconds \1/4 inches	100
			“	5 seconds \1/4 inches	100

Example 9：

50 parts by weight of the unsaturated acrylate polymer A2, 50 parts by weight of the unsaturated epoxy acrylate B and 7.8 parts by weight of IRG819 are mixed thoroughly with one another. Then 3.4 parts by weight of TiO were added with constant stirring₂41.1 parts by weight of CC, 59 parts by weight of extender pigment T399 and 0.58 part by weight of B318M were slowly added to the resin mixture. The prepared solventless formulation was left overnight to de-air then the formulation was applied to a cold rolled steel substrate at a wet film thickness of 6 mils using a squeegee or paint blade or using a putty knife.

The formulation was cured under a low intensity UV-A light source (H & S Autoshot UVA 400 lamp (radiation wavelength 320-450nm)) at a distance of 3 inches for 2 minutes to give a non-tacky surface with a dry film thickness of 1.6 to 2.0 mils. It has excellent adhesion to cold rolled steel as measured by the cross hatch adhesion test (ASTM D3359-95 and General Motors GM 9071P tape adhesion Tests). The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing. It exhibits excellent hiding power.

Example 10：

50 parts by weight of the unsaturated acrylate polymer A3, 50 parts by weight of the unsaturated epoxy acrylate B and 7.8 parts by weight of IRG819 are mixed thoroughly with one another. Then 3.4 parts by weight of TiO were added with constant stirring₂41.1 parts by weight CC, 59 parts by weight extender pigment T399, 0.58 parts by weight B318M were slowly added to the resin mixture, the solvent-free formulation prepared was allowed to sit overnight to de-air, and then the formulation was applied to a cold rolled steel substrate at a3 mil wet film thickness using a squeegee or paint blade or using a doctor blade.

The formulations were cured under a low intensity UV-A light source (H & S Autoshot UVA 400 lamp (spectral wavelength 320-. The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing. It exhibits excellent hiding power.

Example 11：

50 parts by weight of an unsaturated acrylate polymer A4, 50 parts by weight of an unsaturated epoxy acrylate B and 7.8 parts by weight of IRG819 are thoroughly mixed with one another, 3.4 parts by weight of TiO are then added with constant stirring₂41.1 parts by weight of CC, 59 parts by weight of extender pigment T399 and 0.58 part by weight of B318M were slowly added to the resin mixture. The prepared solvent-free formulation was left overnight to degas. The formulation was then applied to a cold rolled steel substrate at a wet film thickness of 3 mils using a squeegee or paint blade or using a puttying knife.

The formulations were cured under a low intensity UV-A light source (H & S Autoshot UVA 400 lamp (spectral wavelength 320-. The coating may be sanded with #320 grit sandpaper and the substrate coated immediately after curing. It exhibits excellent hiding power.

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (14)

1. An anhydrous composition which is free of ethylenically unsaturated monomers and comprises

A)10 to 90 weight percent of an unsaturated (meth) acrylate polymer or oligomer selected from the group consisting of:

a) an unsaturated urethane (meth) acrylate polymer or oligomer having an isocyanate group content of 1% by weight or less and prepared by reacting:

ai) one or more organic polyisocyanates, and

aii) unsaturated (meth) acrylates selected from

1)0 to 100% by weight of an unsaturated polyether (meth) acrylate polyol having an OH number of 30 to 500 and prepared by reacting an aliphatic polyether di-or polyol with acrylic acid and/or methacrylic acid, and

2)0 to 100% by weight of mono-, di-, tri-or polyhydroxy-C₁-C₁₀-alkyl or C₆-C₁₀Aryl (meth) acrylates, wherein the weight percentages of components aii)1) and aii)2) are based on the total weight of components aii)1) and aii)2) and add up to 100%,

the equivalent ratio of isocyanate to hydroxyl is 0.95: 1 to 1: 0.95,

b) an unsaturated polyether (meth) acrylate polyol having an OH number of from 30 to 100 and prepared by reacting a polyether di or polyol with acrylic acid and/or methacrylic acid, and

c) a mixture of these with a further component,

B)10 to 90 weight percent of an unsaturated epoxy (meth) acrylate that is substantially free of epoxy groups and is prepared by reacting:

bi) one or more organic compounds containing at least one epoxy group and having a number average molecular weight of 130 to 1000,

bii)1.3 to 3.0 carboxyl equivalents of an organic dicarboxylic acid or anhydride having a number average molecular weight of 98 to 166,

biii)1 hydroxyl equivalent of a hydroxyl containing reaction product prepared with a carboxyl to hydroxyl equivalent ratio of from 0.6: 1 to 0.95: 1 of the following components:

1) (meth) acrylic acid and

2) tri-or tetrahydroxyether alcohols having a number-average molecular weight of 180 to 1000 and containing at least two ethylene oxide and/or propylene oxide units as ether moieties,

the ratio of the reactive equivalents of components bii) to biii) to the epoxide equivalents of component bi) is at least 1: 1,

C)0.5 to 6% by weight of one or more photoinitiators, wherein the% by weight of component C) is based on the total weight of components A) and B) and wherein the percentages of components A) and B) add up to 100%, and

D)0 to 90 wt.% of a solvent or solvent mixture, wherein the wt.% of component D) is based on the total weight of components A) and B).

2. The composition of claim 1 comprising 25 to 75 weight percent of component a), 25 to 75 weight percent of component B), and 1 to 4 weight percent of component C).

3. The composition of claim 1 wherein component aii)1) has an OH number of 100 to 400.

4. A composition according to claim 3, wherein component aii)1) has an OH number of 200 to 300.

5. The composition of claim 1, wherein the isocyanate to hydroxyl equivalent ratio is 1: 1.

6. The composition of claim 1 wherein component a) b) has an OH number of from 30 to 70.

7. The composition of claim 6 wherein component A) b) has an OH number of from 35 to 65.

8. The composition of claim 1 wherein from 1.8 to 2.2 carboxyl equivalents of the organic dicarboxylic acid or anhydride component bii) are reacted.

9. The composition of claim 8 wherein 1.9 to 2.1 carboxyl equivalents of the organic dicarboxylic acid or anhydride component bii) are reacted.

10. The composition of claim 1 wherein component bi) contains an average of from 1.5 to 6 epoxy groups per molecule.

11. A composition according to claim 10, wherein component bi) contains on average 1.5 to 2 epoxy groups per molecule.

12. A composition according to claim 1, wherein the equivalent ratio of carboxyl groups to hydroxyl groups in component biii) is from 0.65: 1 to 0.9: 1.

13. In a method of preparing a coated substrate by first applying a coating composition to said substrate and then subjecting the resulting coated substrate to radiation, the improvement wherein said composition is the composition of claim 1 and wherein the radiation has a wavelength of 300nm or greater.

14. A coated substrate prepared by the method of claim 13.