JPH0473718B2 - - Google Patents

Description

Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to a composition for forming a surface layer of a support for a lithographic printing plate, and more specifically to a composition for forming a surface layer of a support on the surface of a support. The present invention relates to a composition that is applied to the surface of a substrate to form a surface layer in order to provide adhesive properties.

(b) Problems to be solved by conventional techniques and inventions Conventionally, the surface of the support of a lithographic printing plate has been subjected to graining treatment to improve adhesion with photosensitive resin, or to make it hydrophilic. Various treatments such as immersion treatment in silicate solution etc. have been carried out to improve the quality.

However, performing these various treatments may cause problems with quality stability, quality control,
The drawback is that equipment, maintenance, etc. are constantly required to be perfect, and as a result, the support for the lithographic printing plate becomes expensive.

Therefore, the present invention aims to improve the hydrophilicity of the support surface and the adhesion to the photosensitive resin by simply applying a specific composition to the surface of the support once.

(c) Means and action for solving the problems That is, the present invention provides an organic solvent with a compound having the general formula RSi(OH) ₃ (wherein R is 1 to 3 carbon atoms).
alkyl group, gamma-macrolopropyl group, vinyl group, 3,3,3-trifluoropropyl group, gamma-glycidoxypropyl group, gamma-methacryloxypropyl group, gamma-mercaptopropyl group, and phenyl group. )
A partial condensate of silane triol (hereinafter simply referred to as "silane triol") represented by (2) polyvinyl alcohol (also simply referred to as "polyvinyl alcohol") with a degree of saponification of 30 to 60%.
(c) a crosslinked product of an alkali polyacrylic acid salt; and (d) an inorganic powder insoluble in the organic solvent. This relates to a composition for use.

Component (a) used in the present invention is a partial condensate of silane triol. Specific examples of silane triols are as follows.

_CH3Si (OH) ₃ , _{C2H5Si (} OH) ₃ , _{C3H7Si (} OH) ₃ ,
_CH2 =CHSi(OH) ₃ , _C6H5Si ( _OH ) ₃ ,
(CH ₃ ) ₂ CHSi(OH) ₃ , F ₃ C−(CH ₂ ) ₂ Si(OH) ₃ , Cl
(CH ₂ ) ₃ Si(OH) ₃ , H ₂ C=O(CH ₃ )COO
( _CH2 ) _3Si (OH) ₃ , HS( _CH2 ) _3Si (OH) ₃ , .

Component (A) is obtained by partially condensing these silane triols alone or in combination. Partial condensation (partial condensate) is a state in which the hydroxy groups of the silane triol do not completely react, and a considerable amount of hydroxy groups remains, for example, about 1 mole per 3 moles of silicon atoms. means. As the silane triol used in the present invention, it is most preferable to use monomethylsilane triol.

A partial condensate of monomethylsilane triol is produced by adding monomethyltrialkoxysilane to a water-alcohol mixed solvent. As the alkoxy group, methoxy group, ethoxy group,
A propoxy group, an isopropyl group, etc. can be used. The reaction mechanism is that monomethylalkoxysilane is hydrolyzed and the resulting monomethylsilane triol is condensed. This condensation is not carried out completely in a water-alcohol mixed solvent, but is carried out partially to obtain a partial condensate of monomethylsilane triol.

When the partial condensate of silane triol is heated or dried, residual hydroxyl groups are condensed to form a three-dimensional network polymer with an (O-Si-O) structure as the skeleton, which becomes the base of the surface layer of the support. It is something. When curing the partial condensate of silane triol, it is preferable to use a curing catalyst such as an alkali metal salt of a carboxylic acid such as sodium acetate, an amine carboxylate, or a quaternary ammonium carboxylate because it facilitates curing.

The component (b) used in the present invention has a saponification degree of 30 to 60.
% polyvinyl alcohol. Saponification degree is 60%
If it exceeds 30%, it becomes insoluble in organic solvents, which is not preferable, and if it is less than 30%, the degree of hydrophilicity is low, which is not preferable.

Component (iii) used in the present invention is a crosslinked product of alkali salt of polyacrylic acid. Examples of the alkali salt of polyacrylate include sodium polyacrylate and calcium polyacrylate. In the present invention, this polyacrylic acid alkali salt is crosslinked with a crosslinking agent. Examples of crosslinking agents include diglycidyl ether compounds such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and glycerin diglycidyl ether, epichlorohydrin, epibromohydrin,
Haloepoxy compounds such as α-methylepichlorohydrin, aldehyde compounds such as glutaraldehyde and glyoxal, and isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate are used. The crosslinked polyacrylic acid alkali salt improves the hydrophilicity of the surface layer of the support and also improves the retention of dampening water.

Component (2) used in the present invention is an inorganic powder that is insoluble in organic solvents. Inorganic powders that are insoluble in organic solvents may be those that are insoluble in organic solvents or have extremely low solubility, such as zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, tin oxide, titanium oxide, iron oxide,
Metal or non-metal oxides such as copper oxide, lead oxide, bismuth oxide, magnesium oxide, manganese oxide, salts such as calcium carbonate and calcium sulfate,
Silicon compounds such as silicon dioxide, natural pigments such as kaolin, bentonite, clay, aluminum, iron,
Examples include various metal powders such as zinc. When an inorganic powder insoluble in an organic solvent is present in the surface layer of a support, it forms fine irregularities on the surface. Further, the particle size of the inorganic powder may be about 320 mesh passes, and the smaller the particle size, the more suitable it is for use in the present invention.

The composition according to the present invention can be obtained by uniformly dissolving or dispersing the components (a) to (d) described above in an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether. and mixed solvents of these alcohols and water,
Acetic acid, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, ethyl cellosolve, butyl cellosolve, acetic acid cellosolve, toluene, xylene, trichloroethylene, chloroform, acetone, tetrahydrofuran, ethylene glycol monoethyl ether acetate, ethylene glycol dimethyl ether, etc. alone or in combination It is used as

In preparing the composition according to the present invention, for example, a trialkoxysilane such as monomethyltrialkoxysilane is added to a water-alcohol mixed solvent, and the silane, which is the component (a), is hydrolyzed and condensed. A partial condensate of triol is produced, and then a crosslinked product of polyvinyl alcohol with a degree of saponification of 30 to 60% as component (b), a polyacrylic acid alkali salt as component (c), and a crosslinked product of polyacrylic acid alkali salt as component (d), which is insoluble in an organic solvent as component Inorganic powder may be added, and if necessary, a chelating agent, pigment, dye, thickener, etc. may be added and vigorous stirring may be performed to defoam.

The quantitative proportions of each component in the composition according to the present invention are preferably as follows. That is, the amount of polyvinyl alcohol is
Polyvinyl alcohol 50-200 parts per 100 parts by weight
It is about 80 to 180 parts by weight, more preferably about 80 to 180 parts by weight. If polyvinyl alcohol is less than 50 parts by weight, the surface layer tends to lack hydrophilicity,
Moreover, if it exceeds 200 parts by weight, the surface layer may melt and cause printing stains. The amount of crosslinked polyacrylic acid alkali salt is silane triol 100
It is about 50 to 200 parts by weight, more preferably about 80 to 150 parts by weight. If the amount of polyacrylic acid alkali salt is less than 50 parts by weight, the ability to retain dampening water on the surface of the support will decrease and the hydrophilicity will tend to decrease, and if it exceeds 200 parts by weight, it will retain dampening water. There is a tendency that the ability to do so does not increase, resulting in uneconomical results. The amount of inorganic powder insoluble in organic solvent is about 30 to 150 parts by weight, more preferably 50 parts by weight, per 100 parts by weight of silane triol.
~120 parts by weight. If the amount of the inorganic powder insoluble in the organic solvent is less than 30 parts by weight, irregularities on the surface of the support tend to vary and halftone dot reproducibility in the image area tends to be poor. Moreover, if it exceeds 150 parts by weight, the amount of penetration of the photosensitive liquid into the support will increase.
As a result, the amount of photosensitive liquid used tends to increase, making it uneconomical.

As the base material for applying the composition according to the present invention, any material may be used as long as it is inexpensive and satisfies the required performance as a lithographic printing plate, such as aluminum, iron, copper, zinc, Foils or plates made of single metals such as lead or alloys thereof; plastic films or sheet-like molded products made of polyester, polypropylene, polyimide, polyacrylonitrile, polycarbonate, polyamide, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, etc. , synthetic paper, art paper,
Various materials such as coated paper, cardboard, thin paper, etc. can be used. Aluminum, zinc, iron, etc. are suitable as the metal base material. As the plastic base material, polyester, polyimide, and polycarbonate, which have relatively high dimensional stability, are suitable. As the paper base material, synthetic paper, coated paper, art paper, and cardboard are suitable.

When applying the composition according to the present invention to a metal substrate, 5%
-Sulfosalicylic acid, ethylenediaminetetraacetic acid, trans-cyclohexane-1,2-diaminetetraacetic acid, butane-1,2,3,4-tetracarboxylic acid, propylenediaminetetraacetic acid, pentamethylenediaminetetraacetic acid, cyclopentane-1, Chelating agents such as 2-diaminetetraacetic acid, cyclohexane-1,4-diaminetetraacetic acid, and 2-hydroxytrimethylenediaminetetraacetic acid may be added to the composition according to the present invention. Furthermore, the substrate does not need to be pretreated prior to application of the composition according to the invention, as long as its surface is not contaminated with oily substances. If necessary, the specific surface area of the substrate surface can be reduced by physically treating the surface of the substrate by wet or dry honing, ball polishing, brush polishing, etc., or by chemically treating it by chemical conversion treatment with acid or alkali. Of course, there is no problem in increasing it.

(d) Examples Example 1 100 parts by weight of monomethyltrimethoxysilane was added to an organic solvent prepared by mixing 700 parts by weight of water and 700 parts by weight of isopropanol, and then the degree of saponification was 55.
After dissolving 100 parts by weight of % polyvinyl alcohol, cross-linked sodium polyacrylate (Sumitomo Chemical
Co., Ltd., product name Sumikagel) 100 parts by weight, particle size 10
100 parts by weight of silicon dioxide having a particle size of ~15 mmμ and 1 part by weight of sodium acetate were added and mixed and stirred to obtain a composition.

This composition was applied to a degreased aluminum thin plate (JIS A-1100, thickness 0.15 mm, dimensions 200 mm x 300
mm) with a #6 bar coater and heated to 100°C.
was heated for 60 seconds to form a surface layer (surface film) to obtain a support for a lithographic printing plate.

A negative photosensitive resin liquid was applied to the surface of this support, and after drying for 1 minute in a hot air dryer at 120°C, a negative film (test pattern: 175 lines,
Halftone dots (3 to 75%) were overlapped and exposed for 30 seconds from a distance of 1 m using an ultra-high pressure mercury lamp (electrical capacity 4 KW).
Thereafter, it was resolved using a developer to obtain a lithographic printing plate.

In this lithographic printing plate, the hydrophilicity of the non-image area and the adhesive strength of the image area were evaluated, and both were found to be good. The hydrophilicity of the non-image area can be evaluated by applying offset ink directly to the non-image area, and then
Water was poured on the surface and judgment was made based on whether the offset ink came off or not, and if it came off, it was evaluated as good. In addition, the adhesive strength of the image area was determined by using a taper type rotary breather (wearing wheel; CS-17, load 1000g), applying offset ink to the wearing wheel, and applying halftone dots (75 lines, 5% mesh area) to the image area. ), and the halftone dots were judged by whether or not they fell off after 1000 wears of that part.If they did not fall off, the halftone dots were evaluated as good.

Furthermore, when this lithographic printing plate was printed on high-quality paper using a Heidel KORD printing machine, more than 50,000 copies of printed matter with good image reproducibility and no printing stains could be obtained.

Example 2 After adding 100 parts by weight of monomethyltrimethoxysilane to an organic solvent prepared by mixing 800 parts by weight of water and 500 parts by weight of methanol, and then dissolving 80 parts by weight of polyvinyl alcohol with a degree of saponification of 40%. , 90 parts by weight of a cross-linked product of sodium polyacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumikagel), 55 parts by weight of titanium oxide with a particle size of 10 to 15 mmμ, and 2 parts by weight of sodium acetate were mixed and stirred to form a composition. I got something.

This composition was used in the same manner as in Example 1 to obtain a lithographic printing plate. This lithographic printing plate had good hydrophilicity in the non-image area and good adhesive strength in the image area.
Further, when printing was carried out in the same manner as in Example 1, more than 50,000 copies of printed matter with good image reproducibility and no printing stains could be obtained.

Example 3 100 parts by weight of γ-glycidoxypropyltrimethoxysilane was added to an organic solvent prepared by mixing 400 parts by weight of water and 1000 parts by weight of isopropanol, and then polyvinyl alcohol with a degree of saponification of 50% was added.
After dissolving 100 parts by weight, a crosslinked product of sodium polyacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumikagel)
50 parts by weight, 30 parts by weight of barium sulfate having a particle size of 10 to 15 mmμ, and 1 part by weight of sodium acetate were added, mixed and stirred to obtain a composition.

This composition was used in the same manner as in Example 1 to obtain a lithographic printing plate. This lithographic printing plate had good hydrophilicity in the non-image area and good adhesive strength in the image area.
Further, when printing was carried out in the same manner as in Example 1, more than 50,000 copies of printed matter with good image reproducibility and no printing stains could be obtained.

(F) Effects of the Invention As explained above, if the composition of the present invention is used, the conventional graining treatment, hydrophilization treatment, etc., are no longer necessary, and the composition can be applied to the surface of the base material to make it hydrophilic. It is possible to obtain a support for a lithographic printing plate having a surface layer having excellent properties and adhesion to a photosensitive resin. If a lithographic printing plate obtained using this support is used, it is possible to print a large amount of printed matter with good reproducibility in the image area and with little printing stain.

Claims (1)

[Claims] 1. In an organic solvent, (a) general formula RSi(OH) ₃ (wherein, R has 1 to 3 carbon atoms)
alkyl group, gamma-macrolopropyl group, vinyl group, 3,3,3-trifluoropropyl group, gamma-glycidoxypropyl group, gamma-methacryloxypropyl group, gamma-mercaptopropyl group, and phenyl group. )
(b) polyvinyl alcohol with a degree of saponification of 30 to 60%; (c) a crosslinked product of an alkali salt of polyacrylic acid; and (d) an inorganic substance insoluble in the organic solvent. 1. A composition for forming a surface layer on a support of a lithographic printing plate, comprising a powder and dissolving or dispersing the following.