CA1204016A

CA1204016A - Actinic light polymerizable coating compositions and method of using the same

Info

Publication number: CA1204016A
Application number: CA000270745A
Authority: CA
Inventors: Gerald W. Gruber
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Ohio Inc
Priority date: 1976-02-02
Filing date: 1977-01-31
Publication date: 1986-05-06
Also published as: GB1571060A; FR2339649A1; JPS52101290A; DE2703863A1; JPS5426253B2; FR2339649B1

Abstract

ABSTRACT OF THE DISCLOSURE

An aromatic ketone photopolymerization activator is present in an actinic light curable composition containing organic polymerizable material containing a plurality of sites of ethylenic unsaturation. The composition is polymerized by exposing it to actinic light. Another aromatic ketone photopolymerization activator having a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole and phenanthrenequinone are present in a second actinic light polymerizable coating composition containing organic polymerizable material containing a plurality of sites of ethylenic unsaturation and ultraviolet light absorbing hiding pigment. Coatings of the second coating composition are polymerized by exposing them to actinic light of a wavelength where absorption by the pigment is substantial and to actinic light of a wave-length where absorption by the pigment is insubstantial.

Description

The use of actinic light polymerizable compositions is becoming mo~e widespread. This growing interest is primarily ocassionecl by the low power requirements of actinic light sources as compared to thermal ovens~ by the low l~vels of environmental pollution which can be obtained, and by the minimal space required or actinic light curing equipment. Nonetheless, several problems have arlsen which have retarded the use of actinic light curable compositions in certain areas.
One problem is that the presence of a photopolymerization activator often imparts an unacceptable degree of instability to the compositions during storage prior to use.
Another problem is that during polymerization by exposure to actinic light, the photopolymerization activator or the reaction products of the photopolymerization activator often imparts an undesirable color to the polymerized composition.
In some uses, as for example in the coating of food and beverage containers, it is frequently desirable to apply an actinic light polymerizable composition to one side of a substrate and cure it by exposure to actinic light. The other side of the substrate is then coated with a heat curable coating composltion and polymerized by baking at elevated temperatures in an oven. Often the presence of the photopoly-merization activator or its reaction products in the actinic light cured coating causes the exterior coating to discolor.
It has now been found that actinic light polymerizable composltions containing certain aromatic ketones as photopolymerization activators possess acceptable storage stability and show insignificant color development upon curing by exposure to actinic light. After poly-merization by exposure to actinic light, the polymerized composition usually shows insignificant color development upon post baking at the temperatures customarily used to crosslink thermally cured organic coating compositions. The photopolymerization activators of the invention may be represented by the formula:

X ~,~_ ~2~ L6 ~ OR
~, whereln R is hydrogen, alkyl containing from one to about twenty-two carbon atoms, benzyl, phenyl, hydroxy-alkyl containing from one to about ten carbon atoms, chloroalkyl containing from one to about ten carbon atoms, bromoalkyl containing from one to about ten carbon atoms, alkoxyalkyl where the alkoxy portion contalns from one to about four carbon atoms and where the alkyl portion contains from one to about ten carbon atoms, or phenoxyalkyl where the alkyl portion contains from one to about ten carbon atoms;
X i~ hydrogen, halo, alkoxy containing from one to about four carbon atoms or alkyl containing from one to about four carbon atoms;
R is preferably alkyl containing from one to about twelve carbon atoms, benzyl or phenyl. Most preferably, R is alkyl containing from one to about four carbon atoms9 alkoxyalkyl where the alkoxy portion contains from about one to about four carbon atoms and where the alkyl portion contains from one to about six carbon atoms or phenyl.
X ifi preferably hydrogen or chloro. X i9 preferably loca ed in ~he ortho position although the meta and para positions are satisfactory.
Additional minor substltuents which do not render the compound unsuitable for its intended purpose may be placed on the phenyl ring.
Examples of these photopolymeri~ation activators are:

methyl phenylg].yoxylate ethyl phenylglyoxylate butyl phenylglyoxylate ben~yl phenylglyoxylate J~ - 2 -~2~
butoxyethyl phenylglyoxylate phenoxyethyl phenylglyoxylate dodecyl phenylglyoxyla~e phenyl phenylglyoxylate ethyl o-chlorophenylglyoxylate phenylglyoxylic acid The preferred photopolymerization activators are methyl phenylg]yoxylate, ethyl phenylglyoxylate, butyl phenylglyoxylate and butoxyethyl phenyl glyo~ylate. The esters of phenylglyoxylic acid may be prepared by reacting phenylglyoxyloyl chloride (Kharasch and Bro~m, ~ h~
Chemical Society, vol. 64, page 329 et seq. [19~2]) with the appropriate alcohol.
The photoRolymerization activators of the invention are useful in the photopolymerization of organic polymerizable materlal contain-ing ethylenic unsaturation. The polymerization reaction may be used to form polymers, solutions of polymers, polymer emulsions, coatings, adhesives, and photoresists. A particularly preferred use ls in the formation of hard, infusible thermoset coatings.
There are many types of organic polymerizable materiai which may be used in the practice of the invèntion. In general, these molecules contain one or more sites of ethylenic unsaturation and are capable of being free radically addition polymerized by interaction with the photo-polymerization activator upon exposure to actinic light. The organic poly-merizable material usually comprises molecules containing a plurality ofsuch sites of ethylenic unsaturation. The sites of ethylenic unsaturation may lie along the backbone of the molecule or they may be present in side c'nains attached to the molecular backbone. As a further alternative, both of these configurations may be present concurrently. Most often, the organic polymerizable material comprises ethylenically unsaturated polyester containing a plurality of sites of ethylenic unsaturation, polymer having a plurality of sites of acrylic unsaturation, moaomer having a plurality of sites of acrylic unsaturation or mixture thereof. The term "acrylic unsaturation" as used throughout the specification and claims, unless otherwise quallfied, means unsaturation provlded by unsubstituted acrylyl J~ - 3 -~4~

or ~-substituted acrylyl groups. Examples of ~-stlbstituted acrylyl groups are methacrylyl, ethacrylyl and cC~chloroacrylyl.
The ethylenically unsaturated polyesters constitute a use~ul class of organic polymerizable material. These polyesters are ordinarily esterification products of ethylenically unsaturated polycarboxylic acids and polyhydric alcohols. Usually, the ethylenic unsaturation is in the alpha, beta position.
The ethylenically unsaturated polycarboxyllc acids inlude maleic acid, fumaric acid, aconitic acid, itaconic acid, citraconic acid, mesaconic acid, muconic acid and dihydromuconic acid and halo and alkyl derivatives of such acids. The preferred acids are maleic acid and fumaric acid. Especially preferred is maleic acid. Mixtures of ethylenically un-saturated polycarboxylic acids may be used or only a single such acid may be employed. The anhydrides of these acids, where the anhydrides exist, are, of course, embraced by the term "acid", since the polyesters obtained therefrom are essentially the same whether the acid or anhydride is used in the reaction.
One or more saturated polycarboxylic acids may optionally be utilized in combination with the ethylenically unsaturated acid or anhydride in the preparation of unsaturated polyesters. Such acids7 especially the saturated dicarboxylic acids, increase the leng~h of the polyester without adding additional crosslinking sites, which is a desired feature in some polyesters. Saturated tricarboxylic acids and saturated acids of higher carboxylic functionality may be used to provide oranching where this is desirable.
For purposes of the present invention, the aromatlc nuclei of aromatic acids such as phthalic acid are generally regarded as saturated since the double bonds do not ordinarily react by addition as do ethylenic groups. Therefore, wherever the term "saturated" is utilized, it is to be understood that such term includes aromatic unsaturation or other form of unsaturation which does not react by addition, unless otherwise qualified.

Examples of useful saturated polycarboxyllc acids include oxalic acid, malonlc acid, succinic acid, methylsuccinic acid, 2,2-dimethyl-succinic acid, 2,3-dimethylsuccinic acid, hexylsuccinic acid, glutaric acid,

2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid,

3,3-dimethylglutaric acid, 3,3-diethylglutaric acid, adipic acid, pimelic acid9 suberic acid, azelaic acid, sebaccic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acld, 1,2-hexahydrophthalic acid, 1,3-hexahydrophthalic acid, 1,4-hexahydrophthalic acid9 l,l-cyclo-butanedicarboxylic acid and trans-1,4-cyclohexanedicarboxylic acid. As i.s the case of the ethylenically unsaturated polycarboxylic acids, the anhydrides of the saturated acids, where anhydrides exist, are embraced by the term "acid" since the polyesters obtained therefrom are essentially the same.
The ethylenically unsaturated polycarboxylic acids are usually present in an amount in the range of from about 10 mole percent to about 100 mole percent of the polycarboxylic acids employed. Preferably, they are present in the range of from about 50 mole percent to about 100 mole percent.
The polyhydric alcohols useful in preparing ethylenically unsaturated polyesters include saturated polyhydric alcohols such as ethylene glycol, 1,3-propanediol., propylene glycol, 2,3-butanediol 1,4-butanediol, 2-ethylbutane-1,4-diol, 1,5-pen~anediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanedi.ol, l,10-decanediol, 2,10-decanediol, 1,4-cyclohexanediol, 1,4-dimethylolcyclohexane, 2,2-diethyl-propane-1,3-diol, 2,2-dimethylpropane-1,3-dlol, 3-methylpen~ane 1,4-diol, 2 9 2-diethylbutane-1,3-diol, 4,5-nonanediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, pentaerythritol, erythritol, sorbitol, mannitol, l,l,l-trimethylolpropane, trimethylolethane, and 2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl 3-hydroxypropionate. Ethylenically unsaturated polyhydric alcohols such as 2-butene-1, 4-dio:L may be used alone or in admixture with the saturated polyhydric alcohols. Of course, mlxtures of saturated polyhydrlc alcohols or mlxtures of unsaturated polyhydric al.cohols ~ 5 ~

~g~

may be employed. If unsaturated polyhydric alcohols are used to introduce ethylenic unsaturatlon into the polyegter, the preparatlon of ethylenically unsaturated polycarboxyllc acid may be reduced correspondingly, if desired.
~ ~ixture of ethylenically unsaturated polyesters containing a plurality of sites of ethylenic unsaturation may be used, if deslred.
Another useful class of organic polymerizable material is polymer having a plurality of sites o~ acrylic unsaturation. The sites of acrylic unsaturation may be provided by acrylyl groups or ~-substitu~ed acrylyl groups such as methacrylyl, ethacrylyl and C~-chloroacrylyl. The sites of acrylic unsaturation may be terminal groups of the polymer, they may be in sidechains attached to the molecular backbone of the polymer or both.
Polymers having acrylic unsaturation in sidechains at~ached to the molecular backbone are usually prepared by including one or more monomers which, when interpolymerized with other monomers, to forrn the polymer, provldes reactive sites attarhed tc the polymer along the backbone.
~crylically unsaturated compounds havin~ at least one functional group which will react with the reactive sites on the polymeric backbone are then used to introduce the acrylic unsaturation into the molecule. The usual reactive sites attached directly or indirectly to the polymer are hydro~y, amino, carboxy, carbamyl, isocyanato or epoxy. Hydroxy or carboxy are most often used. When the reactive sites are hydroxy, the acrylically unsa~u-rated compound usually has carboxy, haloformyl (most often chloroformyl) or isocyanato functionality. When the reactive sites on the polymer are amino, the acrylically unsaturated compound usually has isocyanato, halo-formyl (again, most often chloroformyl) or epoxy functionality. When the reactive sites on the polymer are carboxy, the acrylically unsaturated compound generally has hydroxy, epoxy or isocyanato functionality. When the reactive sites are carbamyl, they are usually reacted with formaldehyde to produce ~-methylol carbamy]. groups. When the reactive sites are lso-cyanato, the acrylically unsatura~ed compound ord:lnarily contains hydroxy J~ - 6 -~z~
or carboxy functionality. When the reactlve sites are epoxy (usually glycidyl), the acrylically unsaturated compound generally has carboY.y functionality The acrylically unsaturated cornpound ordinarily contains carboxy, haloformyl or isocyanato functionality.
The polymer having reactive sites attached thereto can itself be any of many types, as for example, polyacryla~es, polyamides, polyesters, polyethers or polyurethanes.
The term polyacrylate is used in its broadest sense to include not only polymerized unsubstituted acrylates, but also polymerized ~-substituted acrylates, such as methacrylates9 ethacrylates and ~-chloro-acrylates. Compounds from any of these subclasses may be used alone, but most often, compounds from two or more subc]asses are interpolymeri~ed.
Examples of suitable monomers which may be used in the preparation of the polyacrylate polymer include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate, methy] methacrylaee~ ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl me~hacrylate, isobutyl metha-crylate, sec-butyl methacrylate, tert-butyl methacrylate3 amyl methacrylate, hexyl methacrylate, hep~yl methacrylate, octyl methacrylate, 2-ethylhegyl methacrylate, decyl methacrylate, dodecyl methacrylate methyl ~-chloro-acrylate, ethyl ~-chloroacrylate, propyl C~-chloroacrylate, hexyl ~-chlcroacrylate, octyl ~-chloroacrylate, decyl ~-chloroacrylate and dodecyl ~-chloroacrylate. Esters of unsubstituted acrylic acid and metha-crylic acld are most often used.
Acrylic monomers which introduce reactlve sites to the polymer molecule include acrylic acid, 2-hydroxyethyl acrylate, 2-hydroxy-propyl acryla~e, 3-hydroxypropyl acrylate, glycidyl acrylate, acrylamide, 2-amino-ethyl acrylate, methacrylie acid, 2-hydroxyethyl me~hacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, glycidyl methacrylate, methacrylamide, 2-aminoethyl methacrylate, 3 aminopropyl ~ - 7 -methacrylate and Ct-chloroacrylic acld.
Other ethylenically unsaturated monomers are often included.
Examples of these compounds are s~yrene arld ~r-me~hylstyrene.
The amount o acrylic monomers which are used to introduce reactive sites to the polymer molecule may vary ~7idely, but they are ordinarily present in the range of from about 3 percent to about 50 percent by weight of the ethylenically unsaturated monomers interpolymerized. An amount in the range of from about 4 percent to about 25 percent is most often the case.
Addition polymeri2ation may be effectuated by combining the ethylenically unsaturated monomers with a free radical initiator and heating the mixture. Exemplary free radical initiators are organic peroxides such as ethyl peroxide and benzoyl peroxide; hydroperoxides such as methyl hydro-peroxide, certain azo compounds such as ~,a'-azobisisobutyronitrile and K ~'-azobis~-cyanovaleric acid); persulfates; peracetates such as methyl peracetate and tert-butyl peracetate; peroxalates such as dimethyl per-oxalate and di(tert-butyl) peroxalate; dlsulfides such as dimethyl thiuram disulfide and Xetone peroxides such as methyl ethyl ketone peroxide. The polymerization may be accomplished in the presence or absence of an inert ?.0 solvent. Temperatures in the range of from about 75 F. to about 400 F. are generally employed. More often, temperatures in the range of from about 100F, to about 300F. are used.
When the polymer is a polyamide, polyester, polyether or polyurethane, the principles are analogous to those given for the poly-acrylates. The known reactions or forming such polymers will~ of course, be used instead of the addition polymerization reaction illustrated above for the polyacrylates.
Other examplPs of satisfactory polymers having a plurality of sites of acrylic unsaturation are acrylic polyester and acrylic polyamide molecules represented by the formulae:

~ - 8 -~ 2~4~

R' E~.' CH2 = Cl ARA ~CRCARi\ CC XCH~

and R' R' G~2==CC ~ARCl ARACC-~ CH2 (II) O O O
n wherein n is an in~eger in the range of from 1 to 4;
each R independently reprcsents a divalent aliphatic, cycloaliphatic or aromatic hydrocarbon radical having from 1 to 10 carbon atoms;
each R' independently represents hydro, methyl or ethyl;
~ and each A independently represents 0 or N~.
It is preferred that every A represent 0. The polyester and polyamide oligomers represented by formula ~I) may be prepared by reacting dicarboxylic acids or acid amides and dihydric alcohols or diamines and then reacting the product with an unsubstituted acrylic acid or an ~-substituted acrylic acid. The acrylic polyester and polyamlde oligomers represented by formula (II) may be prepared by reacting a hydroxy functional monocarboxylic acid, a dimer, trimer or a tetramer of such acid, an amino functional mono-carboxylic acid or a dimer, trimer or tetramer of such acid with an unsub-stituted or ~-substltuted acrylic acid. Where desired, the lactonc may be used in lieu of the hydroxy functional monocarboxylic acid and the lactam may be used in place of the amino functional monocarboxylic acid.
A mixture of polymer3 having a plurality of sites of acrylic unsaturation may be used, if desired.
Another useful class of organic polymerizable material is monomer having a plurality of si~es of acrylic unsaturation. Such monomers ,X - g _ generally comprise divalent, trivalent or tetravalent organic radicals whose bonds are satisfle~ with unsuhstituted acrylyloxy or ~-substituted acrylyloxy groups. The polyvalent radical may be aliphatic, cycloaliphatic or aromatic. Usually, the molecular weight of the monomer is in the range of from about 170 to about 1000. Examples of such monomers are the di~
acrylates and dimethacrylates of ethylene glycol, 193-propanediol, propylene glycol, 2,3-butanediol, 1,4-butanediol, 2 ethylbutane--1,4-diol, 1,5-pentane~
diol, 1,6-hexanediol, 1,7-heptanediol, l,~-octanediol, l,9-nonancdiol, l,10-decaned~ol~ 2,10-decanediol, 1,4-cyclohexanediol, 1,4-dlmethylolcyclo-hexane, 2,2-dimethylpropane-1,3-diol, 3-methylpentane-1,4-diol, 4,5-nonane-diol, diethylene glycol, triethylene glycol, propylene glycol, 5,5-dime~hyl-3,7-dioxanonane-1,9-diol, ~,2-dimethyl-3-hydroxypropyl 2,2-dirnethyl-3-hydroxypropionate, ~ispheno~ A-diglycidyl ether, 1~4-butanediol diglycidyl ether and neopentyl glycol diglycidyl ether; the triacrylates, trimetha-crylates, diacrylates an~ dimethacrylates of glycerol, l,l,l-trimethylol-propane and trimethylolethane; and the tetracrylates, tetramethacrylates, triacrylates, trim~thacrylates, diacrylates and di-methacrylates of penta-erythritol and erythritol. The acrylic groups on the monomer molecules are usually the same, but they may be different as exemplified by the compound 2,2-dimethyl-1-acrylyloxy-3-methacrylyloxypropane.
A mixture of monomers having a plurality of sites of acrylic unsaturation may be used, if desired.
Additional monomers having one or more vinyl groups which crossllnk with the organic polymerizable material containing a ylurality of sites of ethylenic unsaturation heretofore described may optionally be present in the composition. Examples are ~-vinyl-2-pyrrolidone, styrene~
methylstyrene, divinyl benzene, vinyl toluene, vinyl benzoate, vinyl acetate, vinyl propionate and diallyl phthalate. Partlcularly preferred are monomers having monoacrylic functionality which crosslink with the resin having acrylic unsaturat~on which may optionally be present in the coating composition. Examples of monoacrylic functional monomers which may be used are methyl acrylate, methyl methacrylate, ethyl acrylate, ~L2~9L5~

ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexy] methacrylate, octyl acrylate and octyl methacrylate. The preferred vinyl functional monomers are liquid compounds miscible with the resin. The use of one or more vinyl functional monomers is desirable, A benefit is that the vinyl functional monomer usua]ly acts as a reactive solvent for the resin thereby providing compo-sitions having a satisfactorily low viscosity without using an inordinate amount, if any at all, of volatile, nonreactive solvent.
The vinyl functional monomer, or mixtures of vinyl functional monomers, may be employed over a broad range. At the lower end of the range, no vinyl functional monomer need be used. At the upper end of the range, about 80 percent by weight of the binder can be vinyl functional monomer. Often, the vinyl functional monomer will be present in the coating composition in the range of from about 1 to about 80 percent by weight of the binder of the coating composition. Ordinarily when used, the vinyl functional monomer will be in the range of from about 15 to about 30 percent by weight of the binder.
Extender pigments which are generally transparent to ultra-violet light are optional ingredients which are often included in ehe composition. Examples of suitable extender pigments are finely divided particles of silica, barytes, calcium carbonate, talc, magnesium silicate, aluminum silicate, etc. When used, e~xtender pigment is generally present in an amount in the range of from about 1 to about 70 percent by weight of the composition. An amount in the range of from about 1 to about 50 percent is more often employed. Most often, it is present in the range of from about 1 to about 35 percent by weight of the composition. Although a single extender pigment is ordinarily used, mixtures of several extender pigments are satisfactory.
Ultraviolet light absorbing pigments may optionally be used in amounts which do not preclude polymerization of the interior of the actinic light curable composition. The maximum amount is therefore related X

4Q~L6 to the thickness of the composition to be polymerl~ed. Thin coatings may tolerate more ultraviolet light absorblng pigment than thick coatings.
When ultraviolet light absorbing pigment is used, it is usually present in the range of from about 1 percent to about 70 percent by weight based on the weight of the binder. ~or thicker sections, from about 1 percent to about S0 percent are ordinarily satisfactory. Examples of suitable ultra-violet light absorbing pigments are titanium dioxide, antimony oxide, zinc oxide, zirconium oxide, zinc sulfide and lithopone. Mixtures o~ pigments may be used.
Another optional ingredient which is often included in the composition is an inert volatile organic solvent. Mixtures of several inert volatile organic solvents may be used when desired. Examples of suitable inert volatile organic solvents are acetone, methyl ethyl ketone, methyl isobutyl ~etone, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, sec-butyl alcohol, isobutyl alcohol, tert-butyl alcoholj amyl alcohol9 hexyl alcohol, 2-ethylhexyl alcohol, cellosolve, ethyl cellosolve, cellosolve acetate, 2-ethylhexyl acetate, tetrahydrofuran, and aliphatic naphtha. When inert volatile organic solvent is used, it is usually present in the range of from about 1 to about 15 percent by weight of the vehicle.
Another optional ingredlent is resinous pigment dispersant or grinding vehicle. There are many resinous dispersants which are com-mercially available for that purpose. These resins are often low molecular weight resins which have a high carboxyl content. Illustrative of such pigment dispersants are the so-called acrysol dispersants such as Acrysol 1-94, a copolymer of ~utyl acrylate, methyl methacrylate, styrene and acrylic acid, available commercially from the Rohm and Haas Company. These dispersants are used in the manner and in amounts ~nown to the art.
Conventional plasticizers such as dibutyl phthalate, butyl benzyl phthalate, diisooctyl phthalate, decyl butyl phthalate, diisooctyl adipate, dibutyl sebacate, butyl benzoa~e triisooctyl trimellitate, n-octyl n-decyl trimellitate, and tricresyl phosphates and flow promoters such as ~2~ 6 phenyl ben~oate, dibe~yl ketone, benzyl methyl ketone and the like may also be optiona]ly included in amounts customary in the art.
Various conventional chain modi~ying agents of chain~transfer agents may be included in tlle mixture. The preferred chaln-transfer agents are the mercaptan compaunds such as dodecyl mercaptan, tertiary-dodecyl mercaptan, octyl mercaptan, hexyl mercaptan and the like. The quantity and manner of use are also known in the art.
~ ny of the conventional viscosity con~rol agen~s may be optionally employed in the composition. The preferred materials are resinous or polymeric viscosity control agents. Many of these resinous materials are available. Illustrative of such materials are cellulose acetate butyrate, sodium carboxymethyl cellulose and the like. The use of SUCll reslnous or polymeric viscosity control agents is advantageous in that it permits the mixture to be prepared in the form of a viscous mass or syrup having sufficient viscosity to remain in place on the sub-strate until polymeriæation is effected. These viscosity control agents are used in the manner and in amounts known to the art.
The amount of aromatic ketone photopolymerization activator present in the actinic light polymeriæable compositions of the invention may be widely varied. Usually, the photopolymerization activator is present in an amount in the ran~e of from about 0.01 percent to about 50 percent based on the wPight of the binder of the coating composition.
More often, an amount in the range of from about 0.1 percent to about 20 percent ls employed. From about 0.5 to about 10 percent by weight based on the weight of the binder is preferred.
The amount of organic polymerlzable material having a plurality of sites of ethylenic unsaturation present ln the polymerizable composition is subject to wide variation. The material is ordinarily present in an amount in the range of from about 20 to 100 percent by weight of the binder of the composition. An amount in the range of from about 50 to 100 percent is typical. From about ~0 to 100 percent by weight of the binder is preferred.

s~

The polymerizable compositions of the invention are usually prepared by simply admixing the various ingredients. The compounds comprlsing the photocatalyst system may be premixed and then admixed with the other ingredients of ~he coating composition or they may be added separately. Although mixing is usually accomplished at room temperature, elevated temperatures are sometimes used. The maximum temperature which is usable depends upon the heat stability of the ingredients. Temperatures above about 200C are only rarely employed.
The actinic light polymerizable compositions of the invention are generally used to form cured adherent coatings on substrate. The sub-strate is coated with the polymerizable composition using substantially any technique known to ~he art. These include spraying, curtain coating, dipping, roller application, printing, brushing, drawing and extrusion.
The coated substrate is then exposed to ultraviolet light to cure (viz., C-stage) the coating into a hard, infusible film throughout its thickness~
The thicknesses of polymerized coatings of the actinic light polymerizable composition of the invention are subject to wide variation.
Usually, such thiclcnesses are in the range of from about 0.001 millimeter to about 1 milIimeter. More often, they are in the range of from about 0.005 millimeter to about 0.3 millimeter. Typically, they are in the range of from about 0.012 millimeter to about 0.15 millimeter~ When the actinic light polymerizable composition is an actinic light polymerizable printing ink, the polymerized coatlngs usually have thicknesses in the range of from about 0.001 millimeter to about 0.03 millimeter.
The coatings may be polymerized by exposing the coated sub-strate to actinic light. Usually, the actinic light is ultraviolet light having a wavelength in the range of from about 185 to about 400 nanometers.
Any suitable sources of actinic light may be used in the practice of this invention. Suitable sources are mercury arcs9 carbon arcs, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, swirl-flow plasma arc, radio frequency lnduced mercury lamps and ultraviolet light emitting xenon flash lamps. ~articularly preferred ~ - 14 --are ultraviolet light emitting lamps of the medium or high pressure mercury vapor type. Such lamps usually have fused quartz envelopss to withstand the heat and transmit the ultraviolet radiati.on and are ordinarily in the form of long tubes having an electrode at either end. Examples of these lamps are PPG Models 60-2032, 60-0393, 60-0197 and 60-2031 and Hanovia Models 6512A431, 6542A431, 6565A431 and 6577A431.
The times of exposure to actinic light and the intensity of the actinic light to which the polymerizable composition is exposed may vary greatly. Generally, the exposure to actinic light is continued until the C-stage is reached where the film is hard and infuslble throughout its thlckness, although in some instances, as for example in the formation of pressure sensitive adhesives, the exposure is continued only to form a gel (viz., B-stage).
Substrates which may be coated with the compositions of this invention may vary widely in their properties. Organic substrates such as wood, iberboard, particle board, composition board, paper, cardboard and various polymers such as polyesters, polyamides, cured phenolic resins, cured aminoplasts, acrylics, polyurethanes and rubber may be used. Inorganic substrates are exemplified by glass, quartz and ceramic materials. Many metallic substrates may be coated. Exemplary metallic substrates are iron, steel, stalnless steel, copper, brass, bronze, aluminum, rnagnesium~ titanium, nickel, chromium, zinc and alloys. Strippable substrates or substrates including a release coating are sometimes used~ particularly when the poly~erized composition is an adhesive.
The photopolymerization of compounds containing acrylyl or ~ -substituted acrylyl groups such as methacrylyl groups is often inhibited by the presence of oxygen. The oxygen content of air is, in many instances, sufficient to preclude curing the thin layer of the coating having a surface which is adjacent to the air. In many cases, the interior of the coating may be adequately cured, but oxygen inhibition causes the surace to remain tacky and unsuitable for most applications. This phenornenon Ls known in the ~ - 15 -l6 art as inadequate "surface cure". Although it is not desired to be bound by any theory, it is believed that the inhibitlon is due to the formation of peroxide at the site of chain propagation which quenches the reaction and thereby terminates chain growth.
It has now been found that the oxygen inhibition of the photopolymerization of resins containing acrylic group~ may be substantia:Lly reduced by employing at least one aromatic ketone photopolymerization activator of ~he invention. Accordingly, substrates coated with the poly-merizable compositions of the present invention may not only be exposed to actinic light in the presence of an inert atmosphere, viz., an atmosphere either containing no oxygen or only a concentration of oxygen which produces an insignificant degree of polymeri~ation inhibition, but also in the presence of an atmosphere containing a polymerization inhibiting con-centration of oxygen, such as air.
The actinic light polymerizable compositions of the present invention are particularly useful for coating steel and aluminum food and beverage cans.
In the illustrative examples which follow, all parts are parts by weight and percentages are percent by weight unless otherwise specified~
Exam ~
A reactor equipped with a thermometer, a heater, a pressure equalizing addition funnel and an agitator is charged with 275 parts acrylic acid, 4 parts N,N-dimethylcyclohexylamine, 1.6 parts 2,6-di-tert-butyl-p-cresol and 0.015 part hydroquinone. The charge is then heated to 100C. and 500 parts 1,4-butanediol diglycidyl ether (Araldite RD-2, Ciba Geigy) is added dropwise over 6 hours. After the addition is completed, the mixture is held at 100 C. for 2 hours and then cooled to produce a diacrylate of 1,4-butanediol diglycidyl ether product having an acid value of 6.

*Trade Mark ~ - 16 -Seventy-four parts titanium dioxide and 106 parts of the diacrylate of 1,4-butanediol dlglycldyl ether are ground to form a paste.
An intermedia~e composition is prepared by admlxlng 1S5 parts of the paste and 5 parts tributylphosphine.
A first coating composition is prepared by admixing 25 parts of the intermedlate composition ~nd 0.75 part ethyl phenylglyoxylate.
A second coatin~ eomposition is prepared by admi~ing 25 pa~ts of the inter~ediate composltion and 0.75 part benzophenone.
Each coating composition is dra~m down onto separate aluminum substrates with a number 006 wire wound bar to provide films having thick-nesses of about 0.00~ millimeter. The coated substrates are passed twice at 9.1 meters per minute, in air, under four medium pressure mercury vapor lamps, each operating at 78.7 watts per centimeter and emitting both ultra-violet light and visibl~ light. The lamps are 8.89 centimeters above the plane of the substrate surface and are spaced apart at intervals of about 20.3 centimeters. The coating of the first coating composition is found to be polymerized to a wrinkle-free dry coating with fair adhesion to the substrate. The coating of the second coating composition is found to be wrinkled and wet to the touch.
~xample II
A reactor equipped with a thermometer, a heater, a cooler an agitator, a condenser set for total reflux, a source of air and a source of nitrogen i~ charged with 1150 parts acrylic acid, 0.44 part methyl hydroquinone, 6.1 parts 2,6-di-tert-butyl-4-methylphenol, 21.1 parts 2- 2- 4-(1,1,3,3-tetramethylbu~yl)-3-methylphenoxy ethoxy ethyl dimethyl ben~yl ammonium chlorlde monohydrate and 205 parts toluene and a sllght alr sparge is applied. The charge is then heated to 107 C. Over a period o 3-1/2 hours, 2915 parts bisphenol A-diglycidyl ether (Epon 828; Shell Chemical Co.) which has been preheated to a temperature in the range of from 51.6C. to 54.6C. is added to the reactor while maineainlng the *Trade Mark ~ ~ 17 -~%o~

temperature of the reaction mixture in the range of from 107C to 109 C.
Upon completion of the addition, the t.emperature of the reaction mixture is held in the range o~ rom 107C to 110C. for 3-3/4 hours. At the end o~ this per~od, the conden~ser i8 set for total distillation, viz.l no condensate is returned to the reactor, and both air and nitrogen sparges are applied. The reaction mixture is held at a temperature in the range of from 108C, to 113C. for 5 hours and distillate is removed. At the conclusion of this period, heat is shut off, cooling is applied ~nd a slight air sparge is maintained. One hour later when the temperature has reached 90.6C., the product is discharged from the reactor through a nylon bag filter into containers. The product, which is the diacrylate of bisphenol A-diglycidyl ether, is found to have an acid number of 0.5, a hydroxyl number of 214 and to contain 0.01 percent water and 0.2 percent toluene.
A 75 percent solution of the product in ethyl cellosolve has a Gardner-Holdt viscosity of T-U. The product may be depicted as having the structural formula:

CN2=~Cll~oCN2fHCN20 -~-C-~> -OC}12CNC1120'~_C_~-ocN2cl~cN:2occN=cH2 n where the value of n is in the range of from O to about 1.
A reactor equipped with a heater, a cooler, an agitator, a distillation column, condenser, phase separator, a source of air and a source of nitrogen is charged with 1150 parts 2,2 dimethylpropane-1,3-diol ~Vi2., neopentyl glycol)~ 1830 parts acrylic acid and 66.5 parts hydro-quinone. The condenser and phase separator are set for azeotropic distil-lation and heat is applied to melt the charge. Three hundred twenty-five parts cyclohexane and 165 parts p~toluene sulfonlc acid are added to the melt.

*Trade Mark ~ - 18 -~4~ 6 The reaction mixture is then heated to 79C, when reflux is observed and the removal of water is begun. Three hours and ~en minutes later when 403 parts water have been removed and the temperature has rlsen to 102 C., 55 parts cyclohexane is added. After a period of 55 minutes, the tempera-ture has dropped to 99C. Over the next 1-1/2 hours, the temperature rises to 103 C. At this point, a total of 479 parts water has been removed.
The source of heat is thereupon removed, cooling ls applied and the removal of water is halted. When the temperature has dropped to 27 C., filtrati~n of the reaction mixture through a filter bag into a container is begun.
Twenty-five minutes later (temperature: 23C.), the filtration is completed and the addition of 1445 parts cyclohexane is begun. Thirty minutes later (temperature: 18 C.), the addition is completed. Approximately half of the filtered reaction mixture is charged back into the reactor and washed with 455 parts of 20 percent aqueous sodium hydroxide solution. After withdrawing the aqueous layer, the organic layer is discharged into con-tainers. The remaining half of the filtered reaction mixture is charged to the reactor. Thereafter, 1500 parts cyclohexane and 455 parts 20 percent aqueous sodium hydroxide solution are added and the mixture well agitated.
After settling, the aqueous layer is removed. The organic layer is dis-charged into containers and the reactor is flushed with cyclohexane whic'n is removed. The washed product is then transferred from containers, to the reactor in two increments. Additions totaling 5.6 par~s p-methoxyphenol are made. After mixing well, the material is discharged into ~ontainers.
The material is next passed through a continuous vacuum flash-stripper operating at an absolute pressure o~ about 17 kilopascals (1 pascal=l newton per square meter) and a temperature of about 127 C. where 1429 parts stripped product and 3134 parts condensed vapor (essentially cyclohexane) are recovered. The str~pped product is found to have an acid number of 0.9, a Gardner-Holdt viscosity of A , a Gardner color of 1-2 and to contain 0.06 percent water. Next, 1350 parts of the stripped product is subjected to further stripping in a batch vacuum disti]lation apparatus until the temperature of the remaining liquid (1250 parts) is 54.4 C, at an absolute ~ - 19 -~L2~4~

pressure of 3.2 kilopascals. The liquid is cooled to about 27 C., the vacuum is broken with nitrogen and the product i9 discharged into containers.
The product is a 1,3-bis(acrylyloxy)-2,2-dimethylpropane (vi~., diacrylate of neopentyl glycol) composition having a solids content of 99~ percent, a Gardner-Holdt ~iscosity of A , an acid number of less than one and a Çardner color of less than one.
A mixed resin composition is prepared by admixing 500 parts of the diacrylate of bisphenol A-diglycidyl ether and 500 parts of the 1,3-bis-(acrylyloxy)~2,2-dimethylpropane composition.
io A first coating composition is prepared by admixing lO0 parts of the mixed resin composition and 2 parts ethyl phenylglyoxylate.
A second coating composition is prepared by admixing lO0 parts of the mixed resin composition and 2 parts dimethylbenzil.
A third coating composition is prepared by admixing 100 parts oE the tnixed resin composition and 2 parts benzophenone.
Each coating composition is drawn down on a plurality of separate substrates. Substrates coated with each ~oating composition are passed once, in air, under a source of ultraviolet light at various speeds in order to ascertain the maximum speed at ~hich polymerization to a hard, dry coating could be obtained. The maximum speed for satisfac~orily poly-merizing the first coating composition is found to be 15.2 meters per minutes. The maximum speed for the second coating composition is found to be much less than 15.2 meters per mlnute. The coating of the third coatillg composition is observed to be substantially unpolymeri~ed at a speed of 9.1 meters per minute.

The preparation of 3-acrylyloxy-2,2-d~nethylpropyl 3-acryly-loxy-2,2-d~methylpropionate ls desc~ibed in Example 1 of United States Patent No. 3,645,984.

A first coa~ing composition is prepared by admixing 100 parts of 3-acrylyloxy-2,2-dimethylpropyl 3-acrylyloxy-2,2-dlmethylproplonate and 2 parts phenylglyoxylic acid.

A second coating composltion is prepared by admixing 100 parts of 3-acrylyloxy-2,2-dimethylpropyl 3-acrylyloxy 2,2-dimethylpropionate and 2 parts isobutyl benzoin ether.
A third coating composition is prepared by admixing 100 parts of 3-acrylyloxy-2,2-dimethylpropyl 3~acrylyloxy-2,2-dimethylproPionate and 2 parts benzoyl cyanide.
Each coating composition is dra~m down on a plurality of separate aluminum substrates. Substrates coated with each coating composi-tion are passed once, in a nitrogen atmosphere9 under a source of ultra-violet light at various speeds in order to ascertain the maxlmum speed at which polymer~zation to a hard, dry coating which is resistant ~o fingernail scratching, could be obtained. For the first coatlng composition, the maximum speed at which the surface is mar free after the fingernail xcratch test is 15.2 meters per minute. For the second coating compositlon, the maximum speed at which the surface is mar free after the fingernail scratch test is 27.~ meters per minute. For the third coating composition, the maximum speed at which the surface is mar free after the fingernail scratch test is 9.1 meters per minute.
Example IV
._ A urethane resin is prepared in a conventional manner from 2 molar parts 2-hydroxyethyl acrylate and one molar part 2,2,4--trimethylw hexamethylene diisocyanate.
A first coating composition is prepared by admixing lO0 parts

4-hydroxybutyl acrylate, 60 parts of the urethane resln and 3.2 parts isobutyl benzoin ether.
A second coating composition is prepared by admixing 10 parts of the first coating composition and 0.2 part ethyl phenylglyoxylate.
A third coating composition is prepared by admixing 10 parts of the first coating composition and 0.2 part benzophenone.
Each coating composltion is drawn down on two separate sub-strates. One ~ubstrate coated with each coating composition is passed once, in air, under a source oE ultraviolet light operating at 2 kilowatts, X - 2l :

at a speed of 3.05 meters per minute. The other substrate coated with each coating composition is passed once, in air, under the same æource of ultraviolet light at a speed of 6.1 meters per minute. After pa~sage under the source of ultraviolet light, coatings of the first coating composition remain wet to the touch at speeds of both 3.05 meters per minute and 6.1 meters per minute whereas coatln~s of the second and third coating compositions become hard and dry at these speeds.
Rxample V
A coatin~ composition is prepared by admixing 100 parts of the diacrylate of 1,4-butanediol diglycidyl ether of E~ample I, 2 parts N,N-dimethylcyclohexylamine and 2 parts methyl phenylglyoxylate.
The coating composi~ion is drawn down on a substrate and the coated substrate is passed once at 61.0 meters per minute, in air, under the ultraviolet light emitting lamps of Example I to produce a hard, dry coating.
Example VI
A reactor equipped with an agitator, a heater, a packed dis-tillatlon column, a condenser, thermometers and a source of nitrogen ls charged with 272.8 parts ethylene glycol, 296 parts phthalic anhydride and 0.57 part butyl stannoic acid. A nitrogen sparge is applied, the contents of the reactor are heated to 195C. and water is removed from the system.
Fifty minutes later, the temperature has risen to 210 C. The temperature is then held in the range of from about 209C. to about 210C. for ~0 minutes while water is removed. At the end of this time, the distillation column is bypassed so that the vapor from the reactor is vented through a condenser in a manner such that condensate is not returned to the reactor. The liquid is maintained at temperatures in the range of from about 209 C. to about 211 C. for 1-1/4 hours and then discharged into containers. The product polyester resin has an acid number of 0 8~, a Gardner-Holdt viscosity of Z-2 and a total solids content greater than 99 percent.
A reactor equipped with a heater, a cooler, an a~itator, a distillation column, condenser, phase separator, a vacuum source, a source X ~ 22 -~2~ 6 of air and a source of nitrogen is char~ed with 777 parts of the above polyester resin, 475 parts acrylic acid, 173 parts toluene and 9.6 parts hydroquinone. The condenser and phase separa~or are set for total reflux.
The reaction mixture is heated to 49C. at an absolute pressure of about 80 kilopascals and 28.7 parts sulfuric acid is added. The absolute pressure is reduced to about 67 kilopascals and refluxing is observed.
The condenser and phase separator are set for a~eotropic distillation.
One hour later (temperature: 89C.; absolute pressure: 43 kilopascals), 52 parts water has been removed. After another hour (temperature: 94 C.;
absolute pressure: 36 kilopascals), a total of 98 parts water has been removed. After another 45 minutes (temperature: 85C.; absolute pressure:
24 kilopascals), a total of 102 parts water has been removed. ~leat is then removed and cooling is applied. When the temperature reaches 24C., tho vacuum ls broken with nitrogen, 2210 parts toluene and 170 parts normal hexane are added and the mixture is well agitated. The mixture is then washed with 340 parts 20 percent aqueous sodium hydroxide solution using ~itntion while maintaining the temperature below 27 C. Agitation is opped nnd the phases are allowed to separate. The aqueous layer is r~movcd alld 25 parts sodium sulfate is added and admixed with the organic 2~ plla~,e. The mixture is filtere~S into containers to remove solid material.
'rhe flltrate (3188 parts) is charged back into the reactor. A solution is prepared by admixing 1.6 parts hydroquinone and 13.3 parts acetone and the solution (14.9 parts) is added to the reactor. The condenser is set for vacuum distillation. A vacuum is applied to reduce the absolute pressure to about 46.7 kilopascals, the contents of the r~actor are heated to 60 C.
and the removal of distillate is begun. The temperature of the liquid is maintained in the range of from about 52 C. to about 60 C. for 8-1/3 hours while the absolute pressure is gradually reduced to 13.3 kilopascals, and 1835 parts distillate is removed. During the next 3 hours 25 minutes, the ~0 absolute pressure is increased to 16 kilopascals and the temperature is increased to 61 C~ At this time, a total of 2263 parts distilla~e has been )~ - 23 -removed. Distillation is stopped, heat is removed and cooling is begun.
~hen the temperature reaches 27 C., the vacuum is broken with nitrogen.
The stripped product, amounting to 896 parts, is admixed wi~h 180 parts methanol and the mi~ture is subjected to stripping by batch vacuum distlllation until the temperature of the remaining liquid is 60 C. at an absolute pressure of 3.3 kilopascals. The product, amounting to 769 parts, is cooled to about 27C., the vacuum is broken with nitrogen and the product is discharged into containers. This product, a polyester diacryl-ate, has a solids content o~ greater than 99 percent, an acid number of 0.84 and a hydroxyl number of 13.
Several pairs of coating compositions are prepared by admix-ing (~) 2 parts ethyl phenylglyoxylate and 100 parts of an ultraviolet light curable resin, and (B) 2 parts isobutyl benzoin ether and 100 parts of the same resin. Each coating composition is drawn down onto an aluminum substrate with a number 010 wire wound bar. The coated sub-s~rates are passed once, ln air, under the ultraviolet light emitting lamps ~ Fxmnplc I. The exposed coatings are tested for mar resistance by noratchins with a fingernail. Stability to heat is tested by placing the exposed coated substrates in a dark 65.5C. oven until the coating gels or or 20 days, whichever first occurs. The identities of the resins, speeds of passage under the lamps (meters per minute), the mar resistance and the heat stabilities are shown in Table 1, which follows.

~ - 24 -~2~ 6 P~

" " ,, " U ,~
,~ V
h ~ ~
~ 1 40 ~1 C~ V
N R h ).1 :~Xa) :~ h U~ V
~ OQ~ o u~
V ~ r~
~0 ;~ C
H
.C
V

O O ~ ~ O
~ . . . . . U C~
O
V U~ ¢ ¢
~ ~ ~o ¢ _ ~
O .C
~1 .~ P~
N
a).~1 ~ ~
,Q h P~ O O
~1 a) ah~ a~
,~ ,J O O o o o ~ S
O ~1 ~ -1 4 ~1 V l\l\l\
O V~ ~ ~ ~ O
P~ ~
p:~ C ~ C
a~ O o ~ rC
v a~ ~ P. I
~d u ~ Q v o ~C V ~ h V a~ u U~ X ~o~ ~ h C ~1 ,_1 u~ a~
~1 P~ C,C ~ ,C O ~ S
~ oo r~ u a h ,1,~~ ,l v . ~ ~ u a~ ~ ~ ~ ~ ~1a~
P~ X u7~nX ~ 3 a ,) a 4 V
~1ID ~ U~
~1 ~.r~ O ~ r ) 5 .~ uP~ a) X ~ U V ~4 X O O~t ~ O u) h a) h C) 0 ~1 . . . . . Q)a) ,, a) u h 1v :) v ~ ~ q) ~1 ~ t~l ~) U~ rl~ V
_ ~ a~ o u c h ~_ ~ P~¢ ~ E~ ¢ U ~
a .
U~
a) ~ ~ ~ ~ ~ U~

~2~ 6 Example VII
A reactor equipped with a therrnometer, a heater, a cooler, an agitator, a condenser set for total reflux, a source of air and a source of nitrogen is charged with 380.8 parts acrylic acid, 1.87 parts 2,6-di-tert-butyl-4-methylphenol and 1.86 parts triphenyl phosphine and an air spar~e is applied. The charge is then heated to 110C. A mixture compris-ing 385 parts epichlorohydrin and 166.6 parts Epon 828 bisphenol A-diglycidyl ether is preheated to about 110C. 0ver a period of 4 hours, 551.6 parts of the preheated mixture is added to the reactor while main-taining the temperature of the reaction mixture in the range of from 110 C.to 111.7C. ~pon completion of the addition, the temperature o~ the reaction mixture is held in the range of from 110 C. to 113 C. for 75 minutes. At the end of this period ~ternperature 112.2C.), heat is shut of and cooling is applied. Fifteen minutes later (temperature:
96,1C.), the condenser is set for distillation, a slight vacuum of 12 kilopascals is applied while maintaining an air sparge and distillation is begun. Two hours later (temperature: 97.8 C.), 21 parts distillate has ~cen removed nnd the vacuum is removed. Thirty minutes later (temperature:
97~2C.), a sli~ht vacuum of 10.7 kilopascals is applied while maintaining an alr sparge and distillation is again begun. Two hours later (temperature: 97.2C.), 7 additional parts distillate has been removed and the vacuum and air sparge are removed. Fifteen minutes later (temperatur~: 97.8 C.), the vacuum and air sparge are reapplied. Thirty minutes later (temperature: 97.8 C.), the vacuum and air sparge are removed, heat is shut off and cooling is applied. Forty-five minutes later when the temperature has reached 54.4 C., the product is discharged thro~l~h a filter into containers. This intermediate product~ which is a mixture of 3-chloro-2-hydroxypropyl acrylate, 2-chloro-2-(hydroxyrnethyl) ethyl acrylate and the diacrylate of Epon 828 bisphenol A-diglycidyl ether, is found to have an acid number of 3.9, a Gardner-Holdt viscosity of K, a hydroxyl number of 242 and to contain 0.02 percent water and 14.1 percent chlorine.

V

J~ - 26 -Coating Composition A is prepared by admixing 50 parts of the intermediate product and 1 part benzophenone.
Coating Composition B is prepared by admixing 50 parts of the intermediate product, 0.5 part benzophenone and 0.5 part N,N-dimethyl-ethanolamine.
Coating Composition C is prepared by admixing 50 parts of the intermediate product and 1 part isobutyl benzoin ether.
Coating Composition D is prepared by admixing 50 parts oE
the intermediate product and 1 part ~,c~-diethoxyacetophenone.

Coating Composition E is prepared by admixing 50 parts of the intermediate product and 1 part methyl phenylglyoxylate.
Each coating composition is drawn down on a plurality of ~eparate aluminum substrates using a number 014 wire wound draw bar to produce coatings having thicknesses of abou~ 0.02 millimeter. The coated substrates are each passed once, in air, at speeds in the range of from 6.1 to 30.5 meters per minute under the ultraviolet light emitting lamps o~ ~xample 1.
The maxlmum speed at which no fingernail mark could be made ln the exposed coatings and at which the coating could not be removed by ~cratching with a fingernail is ascertained for each coating composition.
The results are shown in Table 2.
Table 2 Maximum Curing Speed For Coating Composi_ion Mar-Free Coating, M/M-ln A 9.1 B 18.3 C 9.1 D 21.3 E 27.4 Example VIII

Five coating compositions are each prepared by admixing 50 parts of the intermediate product of Example VII and a photopolymerization activator. The amounts by weight of photopolymerization activator used are such that the coating compocitions contain about the same molar amount ~ - 27 -~4~6 of photopolymerization activator. Each coating composition is drawn down on a plurality of aluminum substrates. Some coated substrates are passed once, in air, at various speeds under the ultraviolet light emitting lamps of Example I and the degree of cure is ascertained by the fingernail test, The maximum speed which provides little or no mar is determined.
Other coated substrates are similarly exposed in a nitrogen atmosphere and the degree of cure ascertained in like manner. The maximum speed which provldes only a slight ~ar is determined. The identities and amounts of the photopolymerization activators used and the maximum speeds at which the coatings would polymerize to the degree above specified are shown in Table 3.

Table 3 Maximum Curing Photopolymerization Activator Speed, m/min Co~tln~ _ _ Identity Amount, Parts by Wt, In Air In N2 A benzyl phenylglyoxylate 1.2 12.2 15.2 B n-butyl phenylglyoxylate 1.03 15.2 15.2 ethyl phenylglyoxylate 0.89 15.2 15.2 ~ benzophenone 0.91 6.1 12.2 l~ ethyl o-chlorophenylglyoxylate 1,1 12.2 12.2 2~
Example IX
A polyester is prepared in the conventional manner by react-lng 10.6 molar parts propylene glycol, 5 molar parts phthalic anhydride and

5 molar parts maleic anhydride. A resin composition is prepared by thinning the polyester with styrene and the diacrylate of bisphenol A-diglycidyl ether.
Four coating compositions are each prepared by admixing 100 parts by weight resin composition and one part by weight photopolymerization activator. Each coating composition is drawn down on substrates and passed ollce, in air, at various speeds under the ultraviolet light emitting lamps of Example I, and the degree of polymerization is ascertained by the finger-nail test. The maximum speed which provides little or no mar is determined.

~ - 28 _ :~L2~ 6 Relative polymerization rates are calculated by dividing t~e maximum speed of each coating composition by the greatest maximum speed of any coating composition. The identities of the photopolymerization activators and the relative polymerization rates are shown in Table 4.
Table 4 Relative Coating C~E_sition PhotoE~lyme ation ~ctivator Polymerization Rate A Mixture of butyl isomers of 1.00 butyl benzoin ether (Trigonal* 14; Noury Chemical Corp.) B ~thyl phenylglyoxylate 0.40 C Xanthone 0.35 D ~-Phenoxyacetophenone 0.30 ~nother problem that has arisen retarding the use of actinic ligh~ polymerizable coating compositions is that of achieving adequate hiding in coating systems where hiding of the substrate is desired. In theory, one method of obtaining hiding is to incorporate pigments into the coating composition. Unfortunately, many of the pigments known to provide opnclty to non-ratliation curable coatings absorb strongly in most areas of the ultraviolet light region, viz., electromagnetic radiation having wave-lengths in the range of from about 180 nanometers to about 400 nanometers.
This absorption prevents adequate quantities of ultraviolet light from penetrating very far into the interior of the film. The result is in-adequate polymerization of the interior region of the coating, or using the terminology of the art, inadequate "through cure". Ultraviolet light absorbing hiding pigments which are desirably used in coating compositlons due to their excellent hiding characteristics include, but are not limited to, titanium dioxide (including rutile and anatase), zinc sulfide, zinc oxide, antimony trioxide and lithopone. The preferred pigment is titanium dioxide, ~util.e is especially preEerred.
It has now been found that the use of 9,10-phenanthrene-quinone in actinic light polymerizable coating compositions containing *Trade Mark X - 29 _ ultraviolet light absorbing hiding pigments allows the interior of coating of the composition to be adequately polymerized. Although it is not desired to be bound by any theory, it is believed that the reason phenan-threnequinone performs satisfactorily is as follows: ~lthough the pigments absorb light strongly in the ultraviolet region at a wavelength of about 200 nanometers, the absorption diminishes as the wavelength of light is increased~ At about ~100 nanometers, the absorption has diminished to a small value so that a significant portion of such light is able to reach the lnterlor of the coating. The absorption of phenanthrenequinone, how-ever, remains at a high value well into the visible spectrum before it too diminishes to a small value. Phenanthrenequinone is, therefore, suitable for pigmented systems because it absorbs actinic light having a wavelength in a region of substantial pigment transparency and uses the energy of the absorbed photons to produce free radicals capable of causing polymerization of organic polymerizable material containing a plurality of sites of ethylenic unsaturation.
The use of phenanthrenequinone alone is not without dis-a~vantagc, however. Since phenanthrenequinone absorbs photons, as indeed lt must in order to produce free radicals, and since much of the adsorption 2() ls ln the violet and blue regions of the visible spectrum, phenanthrene-quinone is a highly colored compound having a yellow to orange hue.
Although the photoreaction of phenanthrenequinone produces compounds which do not significantly absorb in the visible region and hence are not colored, some of the phenanthrenequinone remains unreacted at the end of the poly-merization process and imparts a yèllow or orange color to the polymerized coating. Yellow and orange coatings are not desirable where opaque white coatings or opaque coatingsof colors other than yellow or orange are desired.
further disadvantage is that phenanthrenequinone does not materially reduce the oxygen inhibition of the polymerization process.
It has now been found that the presence of at least one aromatic ketone photopolymerization activator whlch has a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole causes more complete reaction of the phenanthrenequinone in the thin surface layer resulting in a much whiter appearance of the coating.
According to another embodiment of the present invention, a substrate is coated with a coating composition containing (l~ at least one aromatic ketone photopolymerization activator having a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole, (2) phenanthrenequinone, (3) organlc polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said photo-polymerization activator and said phenanthrenequinone upon exposure toactinic light, and (4) ultraviolet light absorbing hiding pigment. The coated substrate is then exposed to actinic light of two kinds to thereby polymerize the coating into a hard, infusible film throughout its thickness.
Actinic light of the first kind has a wavelength in the ultraviolet region of the spectrum such that the ultraviolet light absorbing hiding pigment ls substantially opaque thereto, and is absorbable by the photopolymeriza-tion activator to produce free radicals capable of causing the polymerization o~ organic polymerizable material. Actinic light of the second kind has a wavelength longer than that of actlnic light of the first kind and such that the ultraviolet light absorbing pigment is substantially transparent thereto. Actinic light of the second kind is also absorbable by phenan-threnequinone to produce free radicals capable of causing polymerization of organic polymerizable material.
The photopolymerization activator and the phenanthrene-quinone constitute one type of photocatalyst system of an embodiment of the invention. Actinic light polymerlzable coating compositions of this e~bodiment contain this photocatalyst system of the invention, organic polymerizable material containing a plurality of sites of ethylenic un-saturation and capable of being free radically addition polymerized by interaction with the photopolymerization activator and the phenanthrene-quinone upon exposure to actinic light and ultraviolet light absorbing ~\ - 31 -~4~6 hiding pigment. It is preferred that the sites of ethylenic unsaturation of the organic polymerizable material be sites of acrylic unsaturation.
As used throughout the instant specification and claims, unless otherwise indicated, the term "acrylic unsaturation" is used in its broad sense to mean the unsaturation provided by unsubstituted acrylyl groups or ~-substituted acrylyl groups such as methacrylyl, ethacrylyl and ~ chloroacrylyl groups.
Examples of photopolymerization activators which may be used in the present invention are:

2~

~ ~ 32 -benz;l 3,4-benzofluorene l-acetylllaphtllalene l -bellzoylnapllthalelle 9-acetylpllellalltllrene 3-acetylphenalltlll^ene 2-acetyln.lpllLlla:Lene 2-benzoy.ll)~l~htha:l.elle 4-phenylbenzop11ellone :10 4-ph~nylacetophe~one anthl.aquinolle 2-methylanth1-aquinoTle thioxanthone 2-chlorotl)ioxanthone 3,4-methylene(lioxyacetophetlolle 4-cyanohenzoE-hen~ne 4-benzoylpyridine 2-benzo~:Lpyri:dille 4,4'-diclllorobell7,opllenone 4-trifluorometllylber~zopllenonc 3-metllox~belli;or)lienone 4--cll~ orobellz(-pllellolle 3-chlorob~nz(lphcnon~
3-benzoylpyridlne 4-methoxybenæopllenone 3,4-dimet:lly:Lbenzophenone 4-metllylbenzaphenone bell7.0pherl0ne 2-methylhcnzophenone 4,~-dimetlly.lbenzophen.olle 2,5-(1imetlllb(enzophenone 2,4-dLmethylben~.opllenone 4-cyanoacoto~ ellone 4-Eluorot-enzophanone o-ben7.0yll en:~ophenolle, 4,4'-dlll~ethoxybanzopllenone 4-acety]~yri(llne 3,4,5-trimetllylacetophenone 3,5-dlmethylacetophenone 4-bromoacetophenone 4-methoxyAcetophenone 3,4-dimethy].acetopherlolle triphenylmethylacetophenone anthrone 4-chloro~cetophenone 4-trl~luoromethylacetophenone 2-chloroanthraqllinone o-benzoylben~,oic acid ethyl benzoy:l.benzoate 50 ~ diben7Ao~ul)erolle o-benzoylbenzophenone acrylylc-xyethyl ben;:oylbenzoate 4-acrylyloxybenzophenone 2-acrylyloxyethoxybenæophenone -A preferred class of photopolymeriza~ion activator comprises the aromatic ketones mentioned before as represented by the formula:

O O
~ OR

wherein R and X comprise the aforementioned constituents.
The amount of aromatic ketone photopolymerization ac~ivator present in the photocatalyst system of this embodiment may vary widely.
Often it is present in the range of from about 25 percent to about 98 per-cent by weight of the photocatalyst system. An amount in the range of from about 35 percent to about 97 percent is typical. From about 45 per-cent to about 95 percent is preferred.
The amount of phenanthrenequinone present in the photo-catalyst system of this embodiment may likewise vary widely. Often it is pr~scnt :Ln the rnnge of from about 2 percent to about 75 percent by weight o~ the photocatalyst system. An amount in the range of from about 3 per-cenc to nbout 65 percent is more often ~Ised. From about 5 percent to about 55 percent is preferred.
The amount of aromatic ketone photopolymerization activator present in the actinic light polymerizable coating compositions is as heretofore described.
The amount of phenanthrenequinone present in the coating composition may also be widely varied. Ordinarily, the phenanthrenequinone i9 present in an amount in the range of from about 0.005 percent to about S percent by weight based on the weight of the binder-of ~he coating composition. ~ost often, an amount in the range of from about 0.01 percent to abo~t 3 percent is used. From about 0.1 percent to about 1 percent by weight based on the weight of the binder is preferred.

The amount of organic polymerizable material havin~ a J~ - 34 ~Z~

plurality of sites of ethylenic unsaturation present in the polymerizable coating composition is as heretofore described.
The ultraviolet light absorbing hiding pigment should csnstitute at lea~t about 5 percent by weight of the actlnic light poly-merizable coating composition of this embodiment. Amounts in the range of from about 5 percent to about 70 percent by weight of the polymerizable coating composition are satisfactory. From about 20 percent to about 70 percent is typical. An amount in the range of from about 33 percent to about 50 percent by weight: is preferred.
The coating composltions of this embodiment of the invention are usually prepared by simply admixing the various ingredients as hereto-~ore described, The pigmented coating compositions containing phenanthrene-quinone may be polymerized by sequentially exposing the coated substrate to actinic light of the first kind and then to actinic light of the second kind. Polymerization may also be accomplished by sequentially exposing contcd substr~te to actinic light of the second kind and then to ~ct;Ln1c Ilght of the first kind. Preferably, however, the coated substrate l~ exposecI ~imIlltaneously to actlnic light of the first kind and to actinic 2n ll~ht o~ thc second kind.
Any suitable sources of actinic light of the first kind and actinic light of the second kind may be used in the practice of this invention. Separate sources for the two kinds of actinic light may be used, but it is preferred to employ a source which emits both actinic light of the first Icind and actinic light of the second kind. Suitable sources include the aforementioned lamps of the specified types.
The wavelengths of electromagnetic radiation which are suLtable for use as actinic light of the first kind and actinic light of the second kind may be ascertained from the general principals and definitions of the two kinds of actinic light heretofore set out. Usually, but not necessarily, actinic light of the first kind has a wavelength in the range of from about 185 to about 380 nanometers and actinic light of 3~

the second kind has a wavelength in the range of from about 380 to about 500 nanometers.
It has now been found that the oxygen inhibition of the photopolymerization of organic polymerizable materials containing a plurality of sites of ethylenic unsaturation may be substantially reduced by employing at least one aromatic ketone photopolymerization activator which has a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole. Accordingly, substrates coated with the coating composition of the present invention may not only be exposed to actinic light in the presence of an inert atmosphere, viz., an atmosphere either containing no oxygen or only a concentration of oxygen uhich produces an insignificant degree of polymerization inhibition, but also in the presence of an atmosphere containing a polymerization inhibiting concentration of oxygen, such as air.
In the illustrative examples which follow, all parts are parts by weight and percentages are percent by weight unless otherwise specified.
Example A reactor equipped with a thermometer, a heater, a cooler, an agitator, a condenser set for total reflux, a source of alr and a source of nitrogen is charged with 380.8 parts acrylic acid, 1.87 parts 2,6-di-tert-butyl-4-methylphenol and 1.86 parts triphenyl phosphite and an air sparge is applied. The charge is then heated to 110 C. A mixture com-prising 385 parts epichlorohydrin and 166.6 parts Epon 828 bisphenol A-diglycldyl ether is preheated to about 110 C. Over a period of 4 hours, 551.6 parts of the preheated mixture is added to the reactor while main-taining the temperature of the reaction mixture in the range of from 110 C.
to 111.7C Upon completion of the addition, the temperature of the re-action mixture is held in the range of from 110 C. to 113 C. for 75 minutes.
At the end of this period (temperature: 112.2 C.), heat is shut off and cooling is applied. Fifteen minutes later (temperature: 96.1 C.), the condenser is set for distillation, a slight vacuum of 12 kilopascala (1 pascal=l newton per square meter) is applied while maintaining an air sparge, and distilla~ion is begun. Two hours later (temperature: 97.8C.), 21 parts distillate has been removed and ~he vacuum is removed. Thirty minutes later (temperature: 97.2C.), a slight vacuum of 10.7 kilopascals is applied while maintaining an air sparge and distillation is again begun.
Two hours later (temperature: 97.2C.), 7 additional parts distillate has been removed and the vacuum and air sparge are removed. Fifteen minutes later (temperature: 97.8C.), the vacuum and air sparge are reapplied.
Thirty minutes later (temperature: 97.8C.), the vacuum and air sparge are removed, heat is shut off and cooling is applied. Forty-five minutes later when the temperature has reached 54.4C., the product is disch~rged throu~h a filter into containers. This intermediate product, which is a mlxture of 3-chloro-2-hydroxypropyl acrylate, 2-chloro-1-(hydroxymethyl) ethyl acrylate and the diacrylate of Epon ~28 bisphenol A~diglycidyl ether, i3 found to have an acid number of 3.9, a Gardner-Holdt viscosity of K, a hy~roxyl numl~er of 242 and to contain 0.02 percent water and 14.1 percent ~l~lorine.
reactor equipped with an agitator, a heater, a packed clls~lllation column, a condenser, thermometers and a source of nitrogen ls charged witl 272.8 parts ethylene glycol, 296 parts phthalic anhydride and 0.57 part butyl stannoic acid. A nitrogen sparge is applied, the contents of ~he reactor are heated to 195 C. and water is removed from the system. Fifty minutes later, the temperature has risen to 210C.
The temperature is then held in the range of from about 209C. to about 210 C. for 40 minutes while water is removed. At the end of this time, the distillation column is bypassed so that the vapor from the reactor is vented through a condenser in a manner such that condensate is not returned to the reactor. The liquid is maintained at temperatures in the range of from about 209 C. to about 211 C. for 1-1/4 hours and then dis-charged into containers. The product polyester resin has an acid number of 0.84, a Gardner-Holdt viscosity of Z-2 and a total solids content greater than 99 percent.
A reactor equipped with a heater, a cooler 3 an agitator, a distillation column, condenser, phase separator, a vacuum source, a source of air and a source of nitrogen is charged with 777 parts of the above polyester resin, 475 parts acrylic acid, 173 parts toluene and 9.6 parts hydroquinone The condenser and phase separator are set for total reflux. The reaction mixture is heated to 49C. at an absolute pressure of about 80 kilopascals and 28.7 parts sulfuric acid is added. The absolute pressure is reduced to about 67 kilopascals and refluxing is observed The condenser and phase separator are set for azeotropic dlstillation One hour later, (temperature: 89 C.; absolute pressure:
43 kllopascals), 52 parts water has been removed. After another hour, (tcmpcrature: 94C.; absolute pressure: 36 kilopascals), a total of 98 parts water has been removed. After another 45 minutes,(temperature:
85 C., absolute pressure: 24 kilopascals), a total of 102 parts water has bcen removed. Heat is then removed and cooling is applied. When the ~emp~rnture reaches 24C., the vacuum is broken with nitrogen, 2210 parts tolllcne and 170 pnrts normal hexane are added and the mixture is ~ell a~itated. The mixture is then washed with 340 parts 20 percent aqueous 2~ sodium hydroxide solution using agitation while maintaining the temperature below 27 C. Agitation is stopped and the phases are allowed to separate.
The aqueous layer is removed and 25 parts sodium sulfate is zdded and ad-mixed with the organic phase. The mixture is filtered into containers to remove solid material. The filtrate (3188 parts) i~ charged back into the reactor. A solution is prepared by admixing 1.6 parts hydroquinone and 13.3 parts acetone and the solution (14.9 parts) is added to the reactor.
The condenser is set for vacuum distillation. A vacuum is applied to reduce the absolute pressure to about 46.7 kilopascals, the con~ents of the reactor are heated to 60 C. and the removal of distillate is begun. The temperature of the liquid is maintained in the range of Erom about 52C. to about 60 C. for 8-1/3 hours while the absolute pressure is gradually reduced to 13 3 kilopascals and 1835 parts distillate is removed. During the next X - 38 _ :~2C~ 6 3 hours 25 minutes, the absolute pressure is increased to 16 kilopascals and the temperature is increased to 61C. At this time, a total of 2263 parts dlstillate has been removed. Distillation is stopped, heat is removed and cooling is begun. When the temperature reachPs 27C., the vacuum i9 broken with nitrogen. The stripped product, amounting to 896 parts, is admixed with 180 parts methanol and the mixture is sub~ected to stripping by batch vacuum distillation until the temperature of the remain ing liquid is 60C. at an absolute pressure of 3.3 kilopascals. The product, amounting to 769 parts, is cooled to abou~ 27C., the vacuum is broken with nitrogen and the product is discharged into containers. This product, a polyester diacrylate composition, has a solids content of greater than 99 percent, an acid number of 0.84 and a hydroxyl number of 13.

A pigment paste is prepared by grinding 200 parts rutile k *
(RTC 2 , Tioxide of Canada) with 100 parts of the above polyester di-acrylate composition.
A coating composition is prepared by admixing 300 parts of thc nbove plgment paste, 3 parts phenanthrenequinone, 300 parts of the abovc intermediate product and 6 parts benzophenone.
The coating composition is spread onto an aluminum substrate 2~ wlth n number 024 wire wound bar to provide a film having a thickness o about 0.03 millimeter. The coated substrate is passed once at 6.1 meters per minute, in air, under four medium pressure mercury vapor lamps, each operating at 78.7 watts per centimeter and emitting both ultraviolet light and visible light.
The lamps are 8.9 centimeters above the plane of the sub-strate surface and are spaced apart at intervals of about 20.3 centimeters.
Passage of the coated substrate under the lamps causes polymerization of the film and prod~ces a hard, adherent, white coating.
Example XI

A reactor equipped with a thermometer, a heater, a pressure equalizing dropping funnel, an agitator and air sparge is charged with *Trade Mark ~ - 39 -725 parts acrylic acid, ~ parts 2,~-di-tert=butyl-p-cresol, 10 parts N~N-dlmethylcyclohexylamine and 0.04 part hydroquinone. The charge is then heated to 100C. and 1300 parts neopentyl glycol diglycidyl ether *

(XD 7114 , Dow Chemical Co.) is added dropwise over 3.67 hours. After the addi~ion is completed, the mixture is held at about 100C. for 5.83 hours and then cooled to produce a diacrylate of neopentyl glycol diglycidyl ether product having an acid value of 14.
One hundred fifty parts of the above diacrylate of neo-pentyl glycol diglycidyl ether and 300 parts RlC 2 rutile are ground using a Cowles blade to form a fine intermediate paste. Three hundred parts of the above diacrylate of neopentyl glycol diglycidyl ether is added to and admixed with the intermediate paste to produce a pigment paste.
Coating Composition A is prepared by admixing 50 parts of t~l~ pigment paste and 1 par~ methyl phenylglyoxylate.
Coating Composition B is prepared by admixing 700 parts of the above pigment paste and 7 parts of phenanthrenequinone using a Cowles l)la~le untll the phenanthrenequinone dissolves.
Coating Composition C is prepared by admixing 50 parts of ~ompo~ltion ~ and 2 parts methyl phenylglyoxylate.
2~ Coating Compositions D through ~l are each prepared by admixing 50 partq of Coating Composition B with 1 part of a photopoly-merization activator additive, the identities of which are shown in Table 1.
~ ach coating composition is drawn down onto separate aluminum substrates with a number 014 wire wound bar to provide films having thicknesses of about 0.02 millimeter. The coated substrates are each passed once at 15.2 meters per minute, in air, under the four lamps of example ~. The results are shown in Table 5, which follows.

*Trade Mark o ~q o u~ ~ ~ ~ ~ ~ ~ ~ ~
~D O CO 1~ ~GO C~ 00 CO 0 ~ ~ o ~ o ~ ~
~ a) o ~cJ ~L: ~1 .C ~1 ,r~ ~1 O J- ~ V ~ V~10 ~ ~0 ~1 CO
C~ ~ ~ ~ 3 a a~ ~ ,- a~ 5 ~J ~ h~ ~J h ~ h h ~~I v u~ ~ ~.1 h h h S~ )~
v~ ~ e J~ V ~J~ ~ ~ V
a a a d a a a ,,~ a~
O ~ ~ ~ 'I ~'I ~ ~ C~
1~ ~.) O C~ tJ U~J CJ O tJ
r~. ~4 X X X X X X X
E~

a a ~
, o~ o ~cn ~ o~
rl .
~ a ~J ~ ~,, ~ ~ ,, ,~
O
~ ~) P~

"
a~
~ ,.
.~ ~d ~n) a) ,1 ,1,~ a ~ x~ x~0~ ~ ~ ~o ,~ P~ ~ ~ a ~ ~
~ ~, ~J~, o ~
~3 ~ a P~ ~a ~1 XO
o ~ a ~ N ~1 ,1 ~ O
a c~ ~ vo O
., e e e e C~
g V
.
a ~
a~
.q ,~ O ~ O~ cn ~ cr~ a~
., ~ o~ o o o o o O o c o P~ ~

r1 '~ O ¢ F4 C~ ~ ~ ~ ~ p~
~ e O O

X

Example XII
One hundred parts of the diacrylate of neopentyl glycol diglycldyl ether is admixed with 200 parts titanium dioxide ~R960; ~.I.
duPont de Nemours and Co.) and ground to a fine paste with a Gowles blade, Three parts phenanthrenequinone is then added and ground into the paste with a Cowles blade, To the resulting mixture are added 300 parts of the dlacrylate of neopentyl glycol diglycidyl ether, 20 parts me~hyl ethyl ketone and 9 parts ethyl phenylglyoxylate. The whole is admixed to form an intermediate composition.
To 90 parts of the above intermediate composition are added 10 parts of methyl ethyl ketone and 10 parts of a 5~ dispersion of phthalo blue pigment in the diacrylate of neopentyl glycol diglycidyl ether.
~fter mixin~, the resulting composition is filtered tc produce a sprayable coating composition.
The sprayable coating composition is sprayed onto a metal substrate to form a film having a thickness of about 0.05 millimeter. The co~ted substrate is passed once at 3.05 meters per minute, in air, under the ~our lamps of Example X to polymerize the film into a hard, adherent, ~lue coating having a high gloss.
?.0 ~ le XIII
A reactor equipped with a thermometer, a heater, an addition f~mnel and an agitator is charged with 918 parts propylene carbonate.
The charge is then heated to about 60C. ~7er a period of one hour, 675 parts N-methyl-ethanolamine is added while maintaining the temperature of the mixture at 60 to 70 C. Upon completion of the addition, the mixture is held at 60 to 70 C. for one hour and cooled to produce a first polyol intermediate .
~ loop reactor equipped wi~h a steam heated heater on one leg, a cooler on the other leg, a thermometer, a pressure gauge and a pump for circulating liquid in the loop i3 charged with 1210 parts of the first polyol intermediate and 14 parts crushed sodium hydroxide. The charge is ~ - 42 -heated to 99C. and maintained in a range of from 99C. to 108 C. at a pressure in the range from about 206 to about 290 kilopascals gauge for about 4-1/2 hours during which time 970 parts propylene oxide is added.
The reactor is cooled and vented and 14 parts crushed sodium hydroxide is added. The reaction mixture ls heated to 99C. and maintained in the range of from 99C to 107C. at a pressure of from about 138 to about 311 kilopascals gauge for about 1-3/4 hours during which time 350 parts propylene oxide is added. The reactor is cooled. The next morning, the reactor is heated to 102C. and malntained in the range of from 101 C. to 107C. at a pressure of from about 206 to about 345 kilopascals gauge for about one hour during which time 270 parts propylene oxide is added. The reactor is held at a temperature of from 105C. to 110C. at a pressure of from about 311 to about 345 kilopascals gauge for about 3/4 hour. The renctor iA then cooled and vented, and the liquid contents of the reactor are drained into a container. The container is found to contain 2688 parts of product which is a second polyol intermediate.
To 2688 parts of the second polyol intermediate is added 2~ parts o~ ~6~ phosphoric acid at 60C. After mixing, a sample of the ~e~ction mixture is taken and diluted with an equal weight of water. The 2~ pll o~ the diluted sample is measured and found to be less than 7Ø A
v~cuum is applied to the reaction mixture and the reaction mixture is heated to 120 C. and held at that temperature for one-half hour. The vacuum is then released, and one percent diatomaceous earth filter aid (Hy-Flo ), based on the weight of total charge, is added. The mixture is then filtered in a pressure filter to form a third polyol intermediate.
A reactor equipped with a thermometer, a heater, an addition funnel, an agitator and an air sparge i9 charged with 222 parts l-isocyana-tomethyl-5-isocyanato-1,3,3-trimethylcyclohexane, 132 parts phenylcellulose acryla~e, 1 part N,N-dimethylcyclohexylamine and 0.2 part dibutyl tin dilaurate. The charge is heated to 50 C. Over a period of one hour, *Trade Mark ~ - 43 -178 parts of the third polyol intermediate is added. Upon completion of the addition, the reaction mixture is held at 50C. for one hour and then at 70 C. for two hours. Over a period of 5 to 10 minutes at 70 C. under an air sparge, 0.5 part 2,6-di-tert-butyl-~-cresol and 1~0 parts 2-hydroxy-ethyl acrylate are added. The reaction mixture is held at 70C. for six hours~ Twenty-five parts 2-hydroxyethyl acrylate is added. The reaction mixture is then held at 85C. for two hours and cooled to produce a poly-urethane terminated with acrylyl groups.
A reactor equipped with a thermometer, a heater, a pressure equalizing addition funnel and an agltator is charged with 275 parts acrylic acid, 4 parts N,N-dimethylcyclohexylamine, 1.6 parts 2,6-di-tert=butyl-p-cresol and 0.015 part hydroquinone. The charge is then heated to 100 C.
and 500 parts 1,4-butanediol diglycldyl ether (Araldite RD-2, Ciba Geigy) ls ndded dropwise over 6 hours. ~fter the addition is completed, the mixture is held at 100 C. for 2 hours and then cooled to produce a di-ncrylate of 1,4-butanediol diglycidyl ether product having an acid value o~ 6.
One hundred parts of the diacrylate of 1,4-butanediol ~liglycidyl ether and 150 parts titanium dioxide are combined and ground 2~ to n Eine paste.
A coating composition is prepared by admixing 25 parts of the above fine paste, 5 parts 2-hydroxyethyl acrylate, 15 parts of the polyurethane terminated with acrylyl groups, 0.45 part phenanthrenequinone and 0.45 part ethyl phenylglyoxylate.
The coating composition is drawn down on an aluminum sub-strnte with a number 009 wire wound bar to provide a film having a thickness of about 0.01 millimeter. The coated substrate is passed once at 45.7 meters per minute, in air, under the four lamps of Example ~ to produce a tough, nearly completely adherent coating.
3~ The coating composition is drawn down on an aluminum substrate with a number 026 wire wound draw bar to provide a film having a thickness ~ - 44 -~ ..__i, of about 0.03 millimeter. The coated substrate is exposed to the four lamps of Example X to produce a flexible coating having high gloss.
According to the provisions of the Patent Stat~es, there are described above the invention and what are now considered to be its best embodiments. However, within the scope of the appended claims, it is to be understood that the invention can be practiced otherwise than as specifically described.

~ - 45 -

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE
IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An actinic light polymerizable composition having a binder comprising:
at least one photopolymerization activator represented by the formula:

wherein (1) R is hydrogen, alkyl containing from one to about twenty-two carbon atoms, benzyl, phenyl, hydroxyalkyl containing from one to about ten carbon atoms, chloroalkyl containing from one to about ten carbon atoms, bromoalkyl containing from one to about ten carbon atoms, alkoxyalkyl where the alkoxy portion contains from one to about four carbon atoms and where the alkyl portion contains from one to about ten carbon atoms, or phenoxyalkyl where the alkyl portion contains from one to about ten carbon atoms; and (2) X is hydrogen, halo, alkoxy containing from one to about four carbon atoms or alkyl containing from one to about four carbon atoms;
and b. organic polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said photopolymerization activator upon exposure to actinic light, said organic polymerizable material comprising ethylenically unsaturated polyester containing a plurality of sites of ethylenic unsaturation, polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or a mixture thereof.

2. The actinic light polymerizable composition of claim 1 wherein:
a. said photopolymerization activator is present in an amount in the range of from about 0.01 percent to about 50 percent by weight of the binder of said composition; and b. said organic polymerizable material is present in an amount in the range of from about 20 to about 100 percent by weight of the binder of said composition.

3. The actinic light polymerizable composition of claim 2 wherein X is located in the ortho position.

4. The actinic light polymerizable composition of claim 2 wherein said photopolymerization activator is selected from the group consisting of methyl phenylglyoxyalate, ethyl phenylglyoxyalate, butyl phenylglyoxyalate and butoxyethyl phenylglyoxyalate.

5. The actinic light polymerizable composition of claim 2 containing at least one additional vinyl functional monomer.

6. The actinic light polymerizable composition of claim 5 wherein said vinyl functional monomer is present in the range of from about 1 to about 80 percent by weight of the binder of said composition.

7. The actinic light polymerizable composition of claim 2 wherein said organic polymerizable material comprises polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or a mixture thereof.

8. The actinic light polymerizable composition of claim 1 further comprising:
a. phenanthrenequinone present in an amount in the range of from about 0.005 percent to about 5 percent by weight based on the weight of the binder of said coating composition;
b. ultraviolet light absorbing pigment present in an amount in the range of from about 5 percent to about 70 percent by weight of said coating composition.

9. A method comprising:
a. coating substrate with an actinic light curable composition having a binder comprising:
(1) at least one aromatic ketone photopolymerization activator represented by the formula:

wherein R is hydrogen, alkyl containing from one to about twenty-two carbon atoms, benzyl, phenyl, hydroxyalkyl containing from one to About 10 carbon atoms, chloroalkyl containing from one to about 10 carbon atoms, bromoalkyl containing from one to about 10 carbon atoms, alkoxyalkyl where the alkoxy portion contains from one to about four carbon atoms and where the alkyl portion contains from one to about 10 carbon atoms, phenoxyalkyl where the alkyl portion contains from one to about 10 carbon atoms, and X is hydrogen, halo, alkoxy containing from one to about four carbon atoms or alkyl containing from one to about four carbon atoms;
and (2) organic polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said photopolymerization activator upon exposure to actinic light, said organic polymerizable material comprising ethylenically unsaturated polyester containing a plurality of sites of ethylenic unsaturation, polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or a mixture thereof; and b. exposing said coated substrate to actinic light which is absorbable by said photopolymerization activator to produce free radicals capable of causing polymerization of sites of ethylenic unsaturation to thereby polymerize the coating into a hard, infusible film throughout its thickness.

10. The method of claim 9 wherein:

a. said photopolymerization activator is present in an amount in the range of from about 0.001 percent to about 50 percent by weight of the binder of said composition; and b. said organic polymerizable material is present in an amount in the range of from about 20 to about 100 percent by weight of the binder of said composition.

11. The method of claim 10 wherein said exposure is conducted in an atmosphere containing a polymerization inhibiting concentration of oxygen.

12. The method of claim 10 wherein said exposure is conducted in air.

13. The method of claim 10 wherein said actinic light has a wavelength in the range of from about 185 to about 400 nanometers.

14. The method of claim 10 wherein X is located in the ortho position.

15. The method of claim 10 wherein said photopolymerization activator is selected from the group consisting of methyl phenylglyoxyalate, ethyl phenylglyoxyalate, butyl phenylglyoxyalate and butoxyethyl phenylglyoxyalate.

16. The method of claim 10 wherein said organic polymerizable materiel comprises polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or a mixture thereof.

17. A method comprising:
a. coating a substrate with an actinic light polymerizable composition having a binder comprising:
(1) a photopolymerization activator selected from the group consisting of methyl phenylglyoxyalate, ethyl phenylglyoxyalate, butyl phenylglyoxyalate and butoxyethyl phenylglyoxyalate, and (2) organic polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said photopolymerization activator upon exposure to actinic light, said organic polymerizable material comprises ethylenically unsaturated polyester containing a plurality of sites of ethylenic unsaturation: polymer having a plurality of site of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or a mixture thereof;
and b. exposing said coated substrate, in air, to actinic light, said actinic light (1) having a wavelength in the range of from about 185 to about 400 nanometers, and (2) being absorbable by said photopolymerization activator to produce free radicals capable of causing polymerization of sites of ethylenic unsaturation, to thereby polymerize said coating into a hard, infusible film throughout its thickness.

18. The method of claim 17 wherein a. said photopolymerization activator is present in an amount in the range of from about 0.01 percent to about 50 percent by weight of the binder of said composition; and b. said organic polymerizable material is present in an amount in the range of from about 20 to about 100 percent by weight of the binder of said composition.

19. The method of claim 18 wherein said organic polymerizable material comprises polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or a mixture thereof.

20. A method comprising exposing to actinic light an actinic light polymerizable composition having a binder comprising:
a. at least one photopolymerization activator represented by the formula:

wherein (1) R is hydrogen, alkyl containing from one to about twenty-two carbon atoms, benzyl, phenyl, hydroxyalkyl containing from one to about ten carbon atoms, chloroalkyl containing from one to about ten carbon atoms, bromoalkyl containing from one to about ten carbon atoms, alkoxyalkyl where the alkoxy portion contains from one to about four carbon atoms and where the alkyl portion contains from one to about ten carbon atoms, or phenoxyalkyl where the alkyl portion contains from one to about ten carbon atoms; and (2) X is hydrogen, halo, alkoxy containing from one to about four carbon atoms or alkyl containing from one to about four carbon atoms;
and b. organic polymerizable material containing ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said photopolymerization activator upon exposure to actinic light, to polymerize said organic polymerizable material.

21. An actinic light polymerizable coating composition having a binder comprising:
a. at least one aromatic ketone photopolymerization activator having a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole;
b. phenanthrenequinone;
c. organic polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said aromatic ketone photopolymerization activator and said phenanthrenequinone upon exposure to actinic light, said organic polymerizable material comprising ethylenically unsaturated polyester containing s plurality of sites of ethylenic unsaturation, polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or mixture thereof; and d. ultraviolet light absorbing hiding pigment.

22. The actinic light polymerizable coating composition of claim 21 Wherein:
a. said photopolymerization activator is present in an amount in the range of from about 0.01 percent to about 50 percent by weight based on the weight of the binder of said coating composition;
b. said phenanthrenequinone is present in an amount in the range of from about 0.005 percent to about 5 percent by weight based on the weight of the binder of said coating composition;
c. said organic polymerizable material is present in an amount in the range of from about 20 to about 100 percent by weight of the binder of said coating composition;
d. said ultraviolet light absorbing hiding pigment is present in an amount in the range of from about 5 percent to about 70 percent by weight of said coating composition.

23. The actinic light polymerizable coating composition of claim 22 wherein said ultraviolet light absorbing hiding pigment is selected from the group consisting of titanium dioxide, zinc sulfide, zinc oxide, antimony trioxide and lithopone.

24. The actinic light polymerizable coating composition of claim 22 wherein said ultraviolet light absorbing hiding pigment is rutile.

25. A method comprising:
a. coating a substrate with an actinic light polymerizable coating composition having a binder comprising:
(1) at least one aromatic ketone photopolymerization activator having n triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole, (2) phenanthrenequinone, (3) organic polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said aromatic ketone photopolymerization activator and said phenanthrenequinone upon exposure to actinic light, said organic polymerizable material comprising ethylenically unsaturated polyester containing a plurality .

of sites of ethylenic unsaturation, polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or mixture thereof; and (4) ultraviolet light absorbing hiding pigment; and b. exposing said coated substrate to actinic light of the first kind and to actinic light of the second kind, said actinic light of the first kind (1) having a wavelength in the ultraviolet region of the spectrum such that said ultraviolet light absorbing hiding pigment is substantially opaque thereto, and (2) being absorbable by said photopolymerization activator to produce free radicals capable of causing polymerization of acrylic groups, said actinic light of the second kind (3) having a wavelength longer than that of said actinic light of the first kind and such that said ultraviolet light absorbing pigment is substantially transparent thereto, and (4) being absorbable by said phenanthrenequinone to produce free radicals capable of causing polymerization of acrylic groups to thereby polymerize said costing into a hard, infusible film throughout its thickness.

26. The method of claim 25 wherein a. said photopolymerization activator is present in an amount in the range of from about 0.001 percent to about 50 percent by weight based on the weight of the binder of said coating composition;
b. said phenanthrenequinone is present in an amount in the range of from about 0.005 percent to a about 5 percent by weight based on the weight of the binder of said coating composition;
c. said organic polymerizable material is present in an amount in the range of from about 20 to about 100 percent by weight of the binder of said coating composition;
d. said ultraviolet light absorbing hiding pigment is present in an amount in the range of from about 5 percent to about 70 percent by weight of said coating composition.

27. The method of claim 26 wherein said exposure is conducted in an atmosphere containing a polymerization inhibiting concentration of oxygen.

28. The method of claim 26 wherein said exposure is conducted in air.

29. The method of claim 26 wherein said actinic light of the first kind has a wavelength in the range of from about 185 to about 380 nanometers wherein said actinic light of the second kind has a wavelength in the range of from about 380 to about 500 nanometers.

30. The method of claim 26 wherein said coated substrate is exposed to both actinic sight of the first kind and to actinic light of the second kind simultaneously.

31. The method of claim 26 wherein said ultraviolet light absorbing hiding pigment is selected from the group consisting of titanium dioxide, zinc sulfide, zinc oxide, antimony trioxide and lithopone.

32. The method of claim 26 wherein said ultraviolet light absorbing hiding pigment is rutile.

33. A method comprising:
a. coating a substrate with an actinic light polymerizable coating composition having a binder comprising:
(1) a photopolymerization activator selected from the group consisting of methyl phenylglyoxyalate, ethyl phenylglyoxyalate, butyl phenylglyoxyalate and butoxyethyl phenylglyoxyalate, (2) phenanthrenequinone, (3) organic polymerizable material containing a plurality of sites of ethylenic unsaturation and capable of being free radically addition polymerized by interaction with said aromatic ketone photopolymerization activator and said phenanthrenequinone upon exposure to actinic light, said organic polymerizable material comprising polymer having a plurality of sites of acrylic unsaturation, monomer having a plurality of sites of acrylic unsaturation or mixture thereof, and (4) rutile;
b. exposing said coated substrate, in air, to actinic light of the first kind and to actinic light of the second kind, said actinic light of the first kind (1) having a wavelength in the ultraviolet region of the spectrum such that said rutile is substantially opaque thereto and (2) being absorbable by said photopolymerization activator to produce free radicals capable of causing polymerization of acrylic groups, said actinic light of the second kind (3) having a wavelength such that said rutile is substantially transparent thereto, and (4) being absorbable by said phenanthrenequinone to produce free radicals capable of causing polymerization of acrylic groups to thereby polymerize said coating into s hard, infusible film throughout its thickness.

34. The method of claim 33 wherein:
a. said photopolymerization activator is present in an amount in the range of from about 0.01 percent to about 50 percent by weight based on the weight of the binder of said coating composition;
b. said phenanthrenequinone is present in an amount in the range of from about 0.005 percent to about 5 percent by weight based on the weight of the binder of said coating composition;
c. said organic polymerizable material is present in an amount in the range of from about 20 to about 100 percent by weight of the binder of said coating composition;
d. said rutile is present in an amount in the range of from about 5 percent to about 70 percent by weight of said coating composition.

35. The method of claim 34 wherein said coated substrate is exposed to both actinic light of the first kind and to actinic light of the second kind simultaneously.

36. In the photopolymerization of monomeric and polymeric composition of photopolymerizable substances wherein a photoinitiator is admixed with a photopolymerizable composition and the mixture exposed to actinic radiation, the improvement wherein photopolymerization is effectively initiated by a member of the group of methyl phenylglyoxyalate, ethyl phenylglyoxalate, tart-butyl phenylglyoxyalate, benzyl phenylglyoxyalate and ethyl p-ethylphenyl-glyoxalate as photoinitiator, said photoinitiator being present in said composition at a concentration of 0.01 to about 30 weight percent.

37. The method of claim 36 wherein the photoinitiator is methyl phenylglyoxyalate.

38. The method of claim 36 wherein the photoinitiator is ethyl phenylglyoxalate.

39. The method of claim 36 wherein the photoinitiator is tertiary butyl phenylglyoxalate.

40. The method of claim 36 wherein the photoinitiator is benzyl phenylglyoxalate.

41. The method of claim 36 wherein the photoinitiator is ethyl-p-ethylphenylglyoxalate.

42. A composition photopolymerizable by actinic radiation comprising unsaturated polymerizable constituents containing dispersed therein from 0.01 to 30 weight percent of a photoinitiating compound of the formula:

wherein R is straight or branched chain hydrocarbon of from one to ten carbon atoms, aryl, aralkyl, or mono-, di- or trialkylsilyl and R' is a heterocyclic radical, aryl of from 6 to 15 carbon atoms or mono-, di- or polysubstituted phenyl with substituents selected from the group consisting of alkyl, alkoxy, arlyloxy, alkylthio, arylthio, and halogen, wherein said unsaturated polymerizable constituents consist essentially of derivatives of acrylic acid.

43. The composition of claim 42 wherein the photoinitiating compound is methyl phenylglyoxalate.

44. An actinic light polymerizable composition comprising at least one unsaturated polymerizable constituent and a photoinitiator compound of the formula:

where R is alkyl, aryl or arlkyl and X is hydrogen, halogen, alkyl or alkoxy.

45. In the photopolymerization of a composition comprising at least one photopolymerizable substance wherein a photoinitiator is mixed with a photopolymerizable composition and the mixture exposed to actinic radiation, the improvement wherein photopolymerization is initiated by compound of the formula:

where a is alkyl, aryl or aralkyl and X is hydrogen, halogen, alkyl or alkoxy.