Photopolymerizable epoxide coating compositions containing titanium dioxide pigment and method of polymerization using same

Claim 2

In an epoxide coating composition, the combination comprising: A. 54.7-89.7 percent by weight of a cationically polymerizable material consisting at least principally of an epoxide prepolymer; B. 10-45 percent by weight of titanium dioxide pigment; and C. 0.3-10.0 percent based upon the weight of said polymerizable material, of a photoinitiator component relatively stable to ambient white light but readily decomposable upon exposure to ultraviolet light to provide a Lewis acid to effect polymerization of said cationically polymerizable material, said photoinitiator component including: a first photoinitiator compound comprising an aryldiazonium salt wherein the aryldiazonium group is selected from the class consisting of 2,5-diethoxy-4-p-tolylmercaptobenzene diazonium, 4-chloro-2,5-dimethoxybenzene diazonium, 2,5-dimethoxybenzene diazonium, 2,5-dimethoxy-4-p-tolylbenzene diazonium and 2,5-dibutoxy-4-benzamidobenzene diazonium, and mixtures thereof, and wherein the salt group is selected from the class consisting of hexafluorophosphates, fluoroborates, fluoroantimonates and fluoroarsenates, and mixtures thereof; and a second photoinitiator compound relatively stable to ultraviolet radiation having a wavelength of at least 355 nanometers and decomposable by ultraviolet radiation having a wavelength of 200-355 nanometers.

Claim 3

The epoxide coating composition of claim 1 wherein said second photoinitiator compound is selected from the class consisting of aryldiazonium salts, diaryldiazonium salts, alkyl/aryldiazonium salts, diaryliodionium salts, alkyl/arylsulfonium salts and bis-(aryl/alkylsulfonium) bis-salts and wherein the salt groups are as set forth for said first photoinitiator.

Claim 4

The epoxide coating composition of claim 1, wherein said second photoinitiator compound is present in a molar ratio relative to said first photoinitiator compound of 0.5-4.0:1.0.

Claim 5

The epoxide coating composition of claim 1 wherein said polymerizable material includes at least about 25 percent by weight of an epoxide ether having the following structural formula: ##STR8## wherein n=1-3 and wherein R is an aliphatic or cycloaliphatic group having 5-12 carbon atoms.

Claim 6

The epoxide coating composition of claim 1 wherein said polymerizable material includes at least about 25 percent by weight of an epoxycarbocyclic ether having the structural formula: R.sup.1 --(R.sup.2).sub.a --O--(CH.sub.2).sub.n --R.sup.3 wherein R 1 is an epoxycarbocyclic group having 4-12 carbon atoms in its ring structure which may be mononuclear or polynuclear; wherein R 2 is a C 1 -C 3 alkyl group; wherein R 3 may be the same as R 1 or an epoxy group having the following general structural formula: ##STR9## wherein R 4 may be hydrogen, a C 1 -C 3 alkyl group or a phenyl group, and such alkyl and phenyl groups may be substituted or unsubstituted; wherein a=0 or 1; and wherein n=1-3.

Claim 7

The epoxide coating composition of claim 1 wherein said polymerizable material includes at least about 25 percent by weight of an epoxidic ester having at least two epoxycycloalkyl groups.

Claim 8

The epoxide coating composition of claim 1 wherein said titanium dioxide pigment is rutile titanium dioxide particles coated with aluminum oxide.

Claim 9

In the method of producing a glossy adherent white coating upon a substrate, the steps comprising: A. admixing to form a polymerizable epoxide composition: (i) 54.7-89.7 percent by weight of a cationically polymerizable material consisting at least principally of an epoxide prepolymer; (ii) 10-45 percent by weight of titanium dioxide pigment; and (iii) 0.3-10.0 percent based upon the weight of said polymerizable material, of a photoinitiator component relatively stable to ambient white light but readily decomposable upon exposure to ultraviolet light to provide a Lewis acid to effect polymerization of said cationically polymerizable material, said photoinitiator component including: a first photoinitiator compound comprising an aryldiazonium salt wherein the aryldiazonium group is selected from the class consisting of 2,5-diethoxy-4-p-tolylmercaptobenzene diazonium, 4-chloro-2,5-dimethoxybenzene diazonium, 2,5-dimethoxybenzene diazonium, 2,5-dimethoxy-4-p-tolylbenzene diazonium and 2,5-dibutoxy-4-benzamidobenzene diazonium, and mixtures thereof, and wherein the salt group is selected from the class consisting of hexafluorophosphates, fluoroborates, fluoroantimonates and fluoroarsenates, and mixtures thereof; and a second photoinitiator compound relatively stable to ultraviolet radiation having a wavelength of at least 355 nanometers and decomposable by ultraviolet radiation having a wavelength of 200-355 nanometers; B. applying said polymerizable composition to a substrate to develop a coating of the desired thickness thereon; and C. exposing said coating to ultraviolet radiation to produce photolysis of said photoinitiator component to generate a Lewis acid and polymerize the epoxide composition within one minute to a hard glossy surface which is tack-free.

Claim 10

In the method of producing a glossy adherent white coating upon a substrate, the steps comprising: A. admixing to form a polymerizable epoxide composition: (i) 54.7-89.7 percent by weight of a cationically polymerizable material consisting at least principally of an epoxide prepolymer; (ii) 10-45 percent by weight of titanium dioxide pigment; and (iii) 0.3-10.0 percent based upon the weight of said polymerizable material, of a photoinitiator component relatively stable to ambient white light but readily decomposable upon exposure to ultraviolet light to provide a Lewis acid to effect polymerization of said cationically polymerizable material, said photoinitiator component including: a first photoinitiator compound comprising an aryldiazonium salt wherein the aryldiazonium group is selected from the class consisting of 2,5-diethoxy-4-p-tolylmercaptobenzene diazonium, 4-chloro-2,5-dimethoxybenzene diazonium, 2,5-dimethoxybenzene diazonium, 2,5-dimethoxy-4-p-tolylbenzene diazonium and 2,5-dibutoxy-4-benzamidobenzene diazonium, and mixtures thereof, and wherein the salt group is selected from the class consisting of hexafluorophosphates, fluoroborates, fluoroantimonates and fluoroarsenates, and mixtures thereof; and a second photoinitiator compound relatively stable to ultraviolet radiation having a wavelength of at least 355 nanometers and decomposable by ultraviolet radiation having a wavelength of 200-355 nanometers; B. applying said polymerizable composition to a substrate to develop a coating of the desired thickness thereon; and C. exposing said coating to ultraviolet radiation to produce photolysis of said photoinitiator component to generate a Lewis acid and polymerize the epoxide composition within one minute to a hard glossy surface which is tack-free.

Claim 11

The method of producing a white coating in accordance with claim 8 wherein said second photoinitiator compound is selected from the class consisting of aryldiazonium salts, diaryldiazonium salts, diaryliodionium salts, alkyl/aryldiazonium salts, alkyl/arylsulfonium salts and bis-(aryl/alkylsulfonium) bis-salts and wherein the salt groups are as set forth for said first photoinitiator.

Claim 12

The method of producing a white coating in accordance with claim 8 wherein said second photoinitiator compound is present in a molar ratio relative to said first photoinitiator compound of 0.5-4.0:1.0.

Claim 13

The method of producing a white coating in accordance with claim 8 wherein said polymerizable material includes at least about 25 percent by weight of an epoxide ether having the following structural formula: ##STR10## wherein n=1-3 and wherein R is an aliphatic or cycloaliphatic group having 5-12 carbon atoms.

Claim 14

The method of producing a white coating in accordance with claim 8 wherein said polymerizable material includes at least about 25 percent by weight of an epoxycarbocyclic ether having the structural formula: R.sup.1 --(R.sup.2).sub.a --O--(CH.sub.2).sub.n --R.sup.3 wherein R 1 is an epoxycarbocyclic group having 4-12 carbon atoms in its ring structure which may be mononuclear or polynuclear; wherein R 2 is a C 1 -C 3 alkyl group; wherein R 3 may be the same as R 1 or an epoxy group having the following general structural formula: ##STR11## wherein R 4 may be hydrogen, a C 1 -C 3 alkyl group or a phenyl group, and such alkyl and phenyl groups may be substituted or unsubstituted; wherein a=0 or 1; and wherein n=1-3.

Claim 15

The method of producing a white coating in accordance with claim 8 wherein said polymerizable material includes at least about 25 percent by weight of an epoxidic ester having at least two epoxycycloalkyl groups.

Claim 16

The method of producing a white coating in accordance with claim 8 wherein said titanium dioxide pigment is rutile titanium dioxide particles coated with aluminum oxide.

Claim 17

The method of producing a white coating in accordance with claim 8 wherein said coating is exposed to ultraviolet radiation in the range of 200-400 nanometers for a period of two to twenty seconds.