JPH0359419B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to photosensitive emulsions for coating plastic films. More specifically, the present invention relates to a photosensitive emulsion for image formation that prevents uneven coating due to bubble formation and repellent phenomenon during coating. A photosensitive material made by coating a plastic film with a photosensitive emulsion containing polyvinyl alcohol, polyacetic acid emulsion, dichromate, or diazo compound is known as a photosensitive image forming material for screen plate making and various other uses. . However, when producing such a photosensitive material, the photosensitive emulsion is coated onto a plastic film, for example, a polyethylene terephthalate film, using a conventional coating device such as a roll coater, air knife coater, curtain coater or slit coater. After coating and drying, many uneven coatings were observed on the surface of the coating film due to bubbles and repelling phenomena that occurred during the preparation and coating process of the photosensitive emulsion, and it was found that precise images could not be obtained. Ivy. The present inventors have studied various antifoaming agents in order to prevent such foaming and repelling phenomena. Mineral oil, fat, fatty acid, fatty acid ester, or alcohol-based products are usually used to prevent foaming in various processes in the textile industry, dye dyeing industry, pulp and paper industry, synthetic rubber latex industry, paint industry, and synthetic resin industry. Various types of antifoaming agents are used, such as silicone-based, polyalkylene glycol-based, fluorine-based, and mixtures thereof. The present inventor added these general antifoaming agents to the photosensitive emulsion of the present application and coated it on a support such as a polyethylene terephthalate film, but although the antifoaming agent was effective in preventing foaming, repelling and other problems occurred. The antifoaming effect was insufficient for those that did not generate oxidation or smearing. As a result of further investigation, the number of carbon atoms is 8.
The present inventors have discovered that the aliphatic alcohol has excellent antifoaming effects and the appearance of the resulting coating film, and does not impair performance such as sensitivity, resolution, printing durability, and solubility resistance, and has thus arrived at the present invention. That is, the present invention relates to an emulsion containing a film-forming polymer compound, a photosensitive emulsion containing polyvinyl alcohol and a diazo compound, and an aliphatic alcohol having 8 carbon atoms as an antifoaming agent in the photosensitive emulsion. The present invention relates to a photosensitive emulsion coated with a plastic film, which is characterized by the following. The photosensitive emulsion of the present invention contains an antifoaming agent, which does not adversely affect the state of the emulsion, and when it is applied onto a plastic film and dried, it does not significantly impair drying properties and the surface of the coating film is There was no generation of bubbles or popping phenomenon. When the present invention is used for screen printing, the photosensitive emulsion of the present invention is first applied to a plastic film such as polyethylene terephthalate film to create a photosensitive film, and the photosensitive film is applied to screen printing using water or light exposure. Attach using a sex emulsion. After drying, the plastic film is removed to provide a screen print with a photosensitive coating of uniform thickness. Hereinafter, the present invention will be explained in more detail by taking as an example the case where the present invention is used for such screen plate making, but the present invention is not limited to this use. Examples of the emulsion containing the film-forming polymer compound in the present invention include vinyl acetate emulsion, acrylic emulsion, and ethylene-based emulsion.
Emulsions containing film-forming polymer compounds such as vinyl acetate emulsion, ethylene-acrylic emulsion, SBR latex, vinyl chloride emulsion, and vinylidene chloride emulsion are used. The polyvinyl alcohol used in the photosensitive emulsion of the present invention preferably has an average degree of polymerization of 500 to 3000 and a degree of saponification of 78 to 98 mol%. If the average degree of polymerization is less than 500, the degree of insolubilization by the diazo compound is low, resulting in poor mechanical strength and water resistance.
When it is high, such as 3000 or more, the viscosity of the composition solution becomes extremely high, making it difficult to coat. Furthermore, the water solubility during development is low, and the washout property of unexposed areas is poor, which is not preferable. Furthermore, when polyvinyl alcohol having a degree of saponification of 78 mol % or less is used, the water solubility is low, and the resulting film is flexible and inferior in strength. On the other hand, if the degree of saponification is higher than 98 mol%, the reactivity with the diazo compound will be low, and the washout properties of unexposed areas will also be poor. As the diazo compound, one or two of tetrazonium salts, diazide compounds, diazo resins which are condensates of diazonium salts and formalin, and other known compounds are used.
More than one species can be mixed and used. The blending composition of polyvinyl alcohol, polyvinyl acetate emulsion and diazo compound in the photosensitive emulsion of the present invention is 70-30:30-70:2
A range of 12 parts by weight is preferred. When the polyvinyl alcohol component is more than 70 parts by weight, the degree of insolubilization by the diazo compound is low, resulting in poor printing durability and water resistance, and poor surface smoothness. On the other hand, if the polyvinyl alcohol component is less than 30 parts by weight, the coating film will have low solvent resistance and printing durability will be poor, and unexposed areas will have poor washout properties, resulting in insufficient development. . In addition, the more the diazo compound component is used, the better in order to sufficiently insolubilize and improve mechanical strength, solvent resistance, and water resistance, but if it is less than 2 parts by weight, crosslinking will be insufficient and a sharp line will not be obtained. If the amount exceeds 12 parts by weight, there is little penetration into the screen and the screen is easily affected by halation. Next, as the aliphatic alcohol having 8 carbon atoms which is the antifoaming agent of the present invention, 1-octyl alcohol,
2-octyl alcohol, 2-ethylhexyl alcohol, and a combination system of two or more thereof can be used. The amount of these antifoaming agents used is 0.0001 to 0.01% by weight, more preferably 0.0005 to 0.005% by weight, based on the weight of the photosensitive emulsion. If it is less than 0.0001 weight, there is no defoaming effect,
Also, if the amount is more than 0.01% by weight, repellency will occur. In addition, in aliphatic alcohols having other carbon numbers,
Aliphatic alcohols with carbon atoms of 6 or less are water-soluble and do not exhibit an antifoaming effect, while aliphatic alcohols with carbon atoms of 10 or more are insoluble in water and therefore have no antifoaming effect, and repellency was observed. These aliphatic alcohols having 8 carbon atoms may be used in combination with other general antifoaming agents or the acetylene glycol compounds and acetylene alcohol compounds previously proposed by the present inventor. Furthermore, a mixture of water and lower aliphatic alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and isopropyl alcohol may be used as the dispersion medium of the photosensitive emulsion containing these antifoaming agents. In the present invention, a photosensitive emulsion containing an antifoaming agent obtained by mixing as described above is applied onto a support using a coating device such as a roll coater, an air knife coater, a curtain coater, or a slit coater, and then dried. This makes it possible to obtain a photosensitive material with no bubbles and a good coated appearance. Examples of plastic films include films of polyethylene terephthalate, polycarbonate, polystyrene, polyvinyl chloride, cellulose acetate, and the like. Examples will be explained below. Examples 1-4, Comparative Examples 1-3 Photosensitive emulsions having the following compositions were prepared. Partially saponified polyvinyl alcohol aqueous solution (average degree of polymerization = 2200, saponification strength = 88 mol%) solid content concentration = 20 wt%) 100 parts by weight polyvinyl acetate emulsion (solid content concentration =
50wt%) 40 parts by weight diazo resin aqueous solution (condensate of diazodiphenylamine salt and paraformaldehyde) (solid content = 25wt%) 9.6 parts by weight Water 100 parts by weight Next, based on 1000 parts by weight of the above photosensitive emulsion As an antifoaming agent, the aliphatic alcohol having 8 carbon atoms of the present invention, a commercially available conventional product, and four other types were added in the weights shown in Table 1, and after mixing, a biaxially oriented polyethylene with a thickness of 75μ was added using a curtain coater. It was applied to one side of a terephthalate film and dried with hot air at 60°C to form a photosensitive coating film with a thickness of 30μ.
The results of evaluating the surface condition of the obtained coating film are shown in Table 1.

[Table] Example 5 A photosensitive emulsion was prepared using the photosensitive emulsion shown in Example 2 and having a dispersion medium composition of methanol/water = 30/70 (weight ratio). Next, a photosensitive coating film was obtained by the same operation as in Example 1. The resulting coating film had a clean appearance without bubbles, repellents, etc., and had good image forming ability. Example 6 1000 was added to the photosensitive emulsion used in Example 5.
In addition to the weight part, an ethylene glycol solution of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (solid content concentration = 50 wt%) 1 is added as an antifoaming agent.
parts by weight were added. Next, a photosensitive coating film was obtained by the same operation as in Example 1. The resulting coating film had a clean appearance without bubbles, repellents, etc., and had good image forming ability.

Claims (1)

[Claims] 1. An emulsion containing a film-forming polymer compound, a photosensitive emulsion containing polyvinyl alcohol and a diazo compound, and in which the photosensitive emulsion contains 8 carbon atoms as an antifoaming agent.
1. A photosensitive emulsion coated on a plastic film, characterized in that it contains an aliphatic alcohol.