Agent for protecting the surface of lithographic printing plate

Claim 2

An emulsion type protective agent for the surface of a lithographic printing plate comprising an aqueous phase having dissolved therein a hydrophilic high molecular weight compound and an oil phase containing an organic solvent, an alkylphenyl type nonionic surfactant having an HLB less than 14, wherein said alkylphenyl nonionic surfactant is represented by the formula (I) ##STR2## wherein R is an alkyl group, p is 1 or 2, m is an integer of 1 to 4, and n is an integer of 2 or more, an aliphatic carboxylic acid ester type surfactant and an anionic surfactant.

Claim 3

The protective agent of claim 1, wherein said aliphatic carboxylic acid ester type surfactant is an ester of an aliphatic carboxylic acid having 12 to 18 carbon atoms and a polyhydroxy alcohol.

Claim 4

The protective agent of claim 2, wherein said aliphatic carboxylic acid ester type surfactant is an aliphatic acid sorbitan type surfactant or an aliphatic acid glycerine type surfactant.

Claim 5

The protective agent of claim 3, wherein said aliphatic carboxylic acid ester type surfactant is selected from the group consisting of sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, monoglyceride-stearate, monoglycerideoleate, glycerol monostearate, and glycerol monooleate.

Claim 6

The protective agent of claim 4, wherein said aliphatic carboxylic acid ester type surfactant is selected from the group consisting of sorbitan monooleate, sorbitan monostearate and monoglyceride stearate.

Claim 7

The protective agent of claim 1, wherein the total amount of surfactants in the oil phase is about 1 to 15% based on the total weight of the protective agent.

Claim 8

The protective agent of claim 1, wherein the proportion of the alkylphenyl nonionic surfactant to anionic surfactant is about 10:1 to 1:10 and the proportion of the alkylphenyl type nonionic surfactant to the aliphatic carboxylic acid ester type surfactant is about 10:1 to 1:10.

Claim 9

The protective agent of claim 1, wherein said alkylphenyl nonionic surfactant is selected from the group consisting of polyoxymethylene octylphenyl ether, polyoxymethylene nonylphenyl ether, polyoxymethylene cetylphenyl ether, polyoxymethylene laurylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene decylphenyl ether, polyoxyethylene laurylphenyl ether, polyoxypropylene octylphenyl ether, polyoxypropylene nonylphenyl ether, polyoxypropylene decylphenyl ether, polyoxypropylene laurylphenyl ether, polyoxypropylene cetylphenyl ether, polyoxybutylene octylphenyl ether, polyoxybutylene nonylphenyl ether, polyoxybutylene decylphenyl ether, polyoxybutylene laurylphenyl ether, polyoxybutylene cetylphenyl ether, and polyoxyethylene dinonylphenyl ether all having an HLB less than 14.

Claim 10

The protective agent of claim 8, wherein said alkylphenyl nonionic surfactant is polyoxyethylene nonylphenyl ether or polyoxyethylene octylphenyl ether.

Claim 11

The protective agent of claim 1, wherein said anionic surfactant is an aliphatic acid salt, an alkyl sulfate ester, an alkylbenzenesulfonate, an alkylnaphthalenesulfonate, a dialkylsulfosuccinate ester, an alkylphosphate ester, a condensate of naphthalene sulfonic acid and formalin, or a polyoxyethylene alkylsulfate ester.

Claim 12

The protective agent of claim 10, wherein said anionic surfactant is a dialkylsulfosuccinate.

Claim 13

The protective agent of claim 11, wherein said dialkylsulfosuccinate is selected from the group consisting of sodium dihexylsulfosuccinate, sodium di(2-ethylhexyl)-sulfosuccinate, sodium dinonylsulfosuccinate and sodium dilaurylsulfosuccinate.

Claim 14

The protective agent of claim 1, wherein the total amount of said nonionic and said anionic surfactant is about 0.5 to about 10 weight % based on the weight of the protective agent.

Claim 15

The protective agent of claim 1, wherein the proportion of said nonionic surfactant to said anionic surfactant is about 10:1 to 1:10.

Claim 16

The protective agent of claim 1, wherein said organic solvent is a plasticizer which solidifies at a temperature less than 15° C. and boils at a temperature higher than 300° C. at atmospheric pressure.

Claim 17

The protective agent of claim 1, wherein said organic solvent is a solvent insoluble in water.

Claim 18

The protective agent of claim 1, wherein said solvent is present in an amount of about 0.1 to 10 weight % based on the weight of the protective agent.

Claim 19

The protective agent of claim 1, wherein said oil phase additionally contains a lipophilic substance which enhances the stability of the emulsion.

Claim 20

The protective agent of claim 1, wherein said hydrophilic polymer is selected from the group consisting of dextrin, gum arabic, an aliginate, a water-soluble cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, an acrylamide copolymer vinylmethyl ether-maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer.

Claim 21

The protective agent of claim 19, wherein said hydrophilic polymer is selected from the group consisting of gum arabic, dextrin, polyvinyl pyrrolidone, carboxymethyl cellulose and polyvinyl alcohol.

Claim 22

The protective agent of claim 20, wherein said hydrophilic polymer is gum arabic.

Claim 23

The protective agent of claim 1, wherein said hydrophilic polymeric compound is present in an amount of about 5 to 40 weight % based on the weight of the plate protective agent.

Claim 24

The protective agent of claim 1, wherein said aqueous phase additionally contains a wetting agent.

Claim 25

The protective agent of claim 23, wherein said wetting agent is a polyhydric alcohol.

Claim 26

The protective agent of claim 1, wherein said aqueous phase additionally contains a water soluble salt.

Claim 27

In a gumming process which comprises coating a protective solution on a lithographic printing plate consisting of a non-image area which retains water and repels a greasy printing ink, and an image-area which repels water and accepts said greasy printing ink, wherein said protective solution comprises an oil phase comprising an organic solvent dissolving a surfactant and an aqueous phase having dissolved therein a hydrophilic high molecular weight compound, the improvement wherein the said oil phase contains a combination of an alkylphenyl type nonionic surfactant having an HLB less than 14, an aliphatic carboxylic acid ester type surfactant and an anionic surfactant, wherein said alkylphenyl nonionic surfactant is represented by the formula (I) ##STR3## wherein R is an alkyl group, p is 1 or 2, m is an integer of 1 to 4, and n is an integer of 2 or more.

Claim 28

In a gumming process which comprises coating a protective solution on a lithographic printing plate consisting of a non-image area which retains water and repels a greasy printing ink, and an image-area which repels water and accepts said greasy printing ink, wherein said protective solution comprises an oil phase comprising an organic solvent dissolving a surfactant and an aqueous phase having dissolved therein a hydrophilic high molecular weight compound, the improvement wherein the said oil phase contains a combination of an alkylphenyl type nonionic surfactant having an HLB less than 14, an aliphatic carboxylic acid ester type surfactant and an anionic surfactant, wherein said alkylphenyl nonionic surfactant is represented by the formula (I) ##STR3## wherein R is an alkyl group, p is 1 or 2, m is an integer of 1 to 4, and n is an integer of 2 or more.

Claim 29

The process of claim 26, wherein said lithographic printing plate is prepared from a presensitized plate.

Claim 30

The process of claim 26, wherein said aliphatic carboxylic acid ester surfactant is an aliphatic acid sorbitan type surfactant or an aliphatic acid glycerine type surfactant.

Claim 31

The process of claim 28, wherein said aliphatic carboxylic acid ester type surfactant is selected from the group consisting of sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, monoglyceridestearate, monoglycerideoleate, glycerol monostearate, and glycerol monooleate.

Claim 32

The process of claim 29, wherein said aliphatic carboxylic acid ester type surfactant is selected from the group consisting of sorbitan monooleate, sorbitan monostearate and monoglyceridestearate.

Claim 33

The process of claim 26, wherein said amount of surfactant(s) in the oil phase is about 1 to 15% based on the total weight of the protective solution.

Claim 34

The process of claim 31, wherein the proportion of the alkylphenyl nonionic surfactant to anionic surfactant is about 10:1 to 1:10 and the proportion of the alkylphenyl type nonionic surfactant to the aliphatic acid ester type surfactant is about 10:1 to 1:10.

Claim 35

The process of claim 26, wherein said alkylphenyl nonionic surfactant is selected from the group consisting of polyoxymethylene octylphenyl ether, polyoxymethylene nonylphenyl ether, polyoxymethylene cetylphenyl ether, polyoxymethylene laurylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene decylphenyl ether, polyoxyethylene laurylphenyl ether, polyoxypropylene octylphenyl ether, polyoxypropylene nonylphenyl ether, polyoxypropylene decylphenyl ether, polyoxypropylene laurylphenyl ether, polyoxypropylene cetylphenyl ether, polyoxybutylene octylphenyl ether, polyoxybutylene nonylphenyl ether, polyoxybutylene decylphenyl ether, polyoxybutylene laurylphenyl ether, polyoxybutylene cetylphenyl ether, and polyoxyethylene dinonylphenyl ether all having an HLB less than 14.

Claim 36

The process of claim 33, wherein said alkylphenyl nonionic surfactant is polyoxyethylene nonylphenyl ether or polyoxyethylene octylphenyl ether.

Claim 37

The process of claim 26, wherein said anionic surfactant is an aliphatic acid salt, an alkyl sulfate ester, an alkylbenzenesulfonate, an alkylnaphthalenesulfonate, dialkylsulfosuccinate ester, an alkylphosphate ester, a condensate of naphthalene sulfonic acid and formalin, or a polyoxyethylene alkylsulfate ester.

Claim 38

The process of claim 35, wherein said anionic surfactant is an dialkylsulfosuccinate.

Claim 39

The process of claim 36, wherein said dialkylsulfonsuccinate is selected from the group consisting of sodium diethylsulfosuccinate, sodium di(2-ethylhexyl)sulfosuccinate, sodium dinonylsulfosuccinate and sodium dilaurylsulfosuccinate.

Claim 40

The process of claim 32, wherein the total amount of said nonionic and said anionic surfactant is about 0.5 to about 10 weight % based on the weight of the protective solution.

Claim 41

The process of claim 32, wherein the proportion of said nonionic surfactant to said anionic surfactant is about 10:1 to 1:10.

Claim 42

The process of claim 26, wherein said organic solvent is a plasticizer which solidifies at a temperatures less than 15° C. and boils at a temperature higher than 300° C. at atmospheric pressure.

Claim 43

The process of claim 40, wherein said plasticizer is present in an amount of about 0.1 to 10 weight % based on the weight of the protective solution.

Claim 44

The process of claim 26, wherein said oil phase additionally contains a lipophilic substance which enhances the stability of the emulsion.

Claim 45

The process of claim 6, wherein said hydrophilic polymer is selected from the group consisting of dextrin, gum arabic, an alginate, a water-soluble cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, an acrylamide copolymer, vinylmethyl ether-maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer.