JPH04240855A - Negative type photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain the negative type photosensitive resin composition for letterpress printing superior in water resistance and printing performance using an aqueous ink by incorporating a specified vinyl alcohol type polymer, a urea derivative, and an unsaturated acrylic urethane type oligomer. CONSTITUTION:This negative type photosensitive resin composition comprises (a) the vinyl alcohol type polymer etherified by acrylamide or methacrylamide of lower alkylol, (b) condensate of urea, thiourea, lower alkylated, lower alkylol- combined, or lower alkylated and lower alkylol-combined derivative, and lower alkylol acrylamide or lower alkylol methacryamide, (c) an unsaturated acrylic urethane oligomer, and (d) a photopolymerization initiator.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a novel negative photosensitive resin composition, and more specifically, a letterpress printing plate that can use water as a developer and has excellent resistance to water-based inks. This invention relates to a negative photosensitive resin composition that can provide the following properties.

0002

[Prior Art] Conventionally, oil-based ink has been used in letterpress printing plates, but the mist of this oil-based ink has a negative effect on the human body, and printed matter made with it takes a long time to dry. Recently, water-based inks have attracted attention because they have drawbacks such as staining hands, and therefore, the emergence of a negative photosensitive resin composition suitable for water-based inks as an alternative to oil-based inks is particularly desired. There is.

On the other hand, conventionally known negative photosensitive resin compositions are developed using organic solvents such as alcohols and halogens as developing solutions (for example, as disclosed in US Pat. No. 3,024). , Specification No. 180, Special Publication No. 1973
-43374, U.S. Patent No. 3,801,328, etc.) and alkaline water developable type or water developable type (for example, Japanese Patent Publication No. 54-3790, Japanese Patent Publication No. 53-208).
Publication No. 2, etc.), but currently there are issues such as safety, working environment,
From the viewpoint of preventing errors in preparing a developer, it is strongly desired to use a water-developable negative photosensitive resin composition.

However, conventional water-developable inks have a problem in that they cannot be printed using water-based inks because they have poor water resistance. Therefore, in order to solve such problems, various negative photosensitive resin compositions have been proposed (Japanese Unexamined Patent Publications No. 61-22339, No. 61-246742, No. 1999). -306836
(Japanese Patent Application Laid-open No. 2-4255).

[0005] However, although these compositions have water-developability and can be printed with water-based ink, they are not completely water-developable, resulting in cloudy developing solutions and the need to add surfactants. In addition, the resulting printing plate has drawbacks such as insufficient water resistance in the relief portion and poor printing durability.

[0006] Polyvinyl alcohol or vinyl alcohol copolymers can also be converted into N-methylol acrylamide or N-methylol acrylamide.
- A water-developable negative photosensitive resin composition containing as a photosensitive component unsaturated polyvinyl alcohol in which 1 to 40 mol% of the hydroxyl groups are converted to acrylamide methyl ether or methacrylamide methyl ether by reacting with methylol methacrylamide. Disclosed (Special Publication No. 49-5923
Publication No.). However, this composition has drawbacks such as low sensitivity and insufficient water resistance of the cured product.

[0007] As described above, all conventional negative-working photosensitive resin compositions have poor water resistance, insufficient printability with water-based inks, and are not completely water-developable. However, there has been a strong desire for improvement.

[0008]

SUMMARY OF THE INVENTION In response to these demands, the present invention provides a water-developable negative photosensitive resin composition that can provide a letterpress printing plate with good water resistance and excellent printability with water-based inks. It was done for the purpose of providing something.

[0009]

[Means for Solving the Problems] As a result of intensive research to develop a negative photosensitive resin composition having the above-mentioned preferable properties, the present inventors have found that specific vinyl alcohol polymers, urea derivatives, With a resin composition containing an unsaturated acrylic urethane oligomer and a photopolymerization initiator,
The inventors have discovered that the object can be achieved, and have completed the present invention based on this knowledge.

Specifically, the present invention provides (A) a vinyl alcohol polymer etherified with lower alkylol acrylamide or lower alkylol methacrylamide;
B) Condensate of urea, thiourea or lower alkylated, lower alkylolated or lower alkyl lower alkylolated derivatives thereof and lower alkylol acrylamide or lower alkylol methacrylamide, (C) Unsaturated acrylic urethane oligomer and (D) a negative photosensitive resin composition comprising a photopolymerization initiator.

In the composition of the present invention, a vinyl alcohol polymer etherified with lower alkylol acrylamide or lower alkylol methacrylamide is used as component (A). Examples of the lower alkylol of the lower alkylol acrylamide or lower alkylol methacrylamide in this vinyl alcohol polymer include methylol, ethylol, propyrrole, and butyrol. Further, the vinyl alcohol polymer may be polyvinyl alcohol obtained by completely saponifying polyvinyl acetate, or may be in the form of a partially saponified product, that is, a vinyl alcohol copolymer having vinyl alcohol units. When using a copolymer, one containing 60 mol% or more of vinyl alcohol units is desirable. Copolymerization components of this copolymer include, for example, vinyl acetate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, styrene, ethylene, propylene, maleic anhydride,
Examples include acrylonitrile, methacrylonitrile, acrylic esters, and methacrylic esters.

The degree of polymerization of this vinyl alcohol polymer is not particularly limited as long as the polymer is water-soluble, but the average degree of polymerization is 200 to 2000, preferably 30.
A value of 0 to 1000 is preferable.

The etherified vinyl alcohol polymer used as component (A) in the present invention is prepared by treating the vinyl alcohol polymer in the presence of an acidic catalyst such as an inorganic acid, a sulfonic acid derivative, or an ammonium halide. It can be produced by reacting with lower alkylol acrylamide or lower alkylol methacrylamide.

The etherified vinyl alcohol polymer thus obtained preferably contains 50 mol% or more of vinyl alcohol units, and the photosensitive resin composition obtained using this polymer has sufficient sensitivity. It is possible to provide a printing plate that has not only the above properties but also satisfactory flexibility, water resistance, and printability.

In the composition of the present invention, urea, thiourea or lower alkylated, lower alkylolated or lower alkyl lower alkylolated derivatives thereof, lower alkylolacrylamide or lower alkylolmethacrylamide are used as component (B). A condensate of is used.

[0016] This condensate is obtained by polycondensing, for example, an alkylol derivative or alkylated alkylol derivative of urea or thiourea and N-alkylol acrylamide or N-alkylol methacrylamide in the presence of an acid or an ammonium salt. or reacting urea or thiourea with formaldehyde to form a linear condensation polymer, which is then grafted with N-alkylol acrylamide or N-alkylol methacrylamide in the presence of an acid or ammonium salt. (Japanese Patent Publication No. 54-3790), or by reacting urea, thiourea or their alkyl derivatives with N-alkylol acrylamide or N-alkylol methacrylamide in water or a hydrophilic organic solvent with an acid. Or those obtained by reacting using an alkali catalyst with stirring in the temperature range of 60 to 95°C for 1 to 5 hours in the presence of a thermal polymerization inhibitor (Japanese Patent Publication No. 1-48528). Can be done. Here, the lower alkyl in the lower alkylated, lower alkylolated, or lower alkyl lower alkylolated derivative includes methyl, ethyl, propyl, butyl, etc., and the lower alkylol includes methylol, ethylol, propyrrol, butyrol, etc. ,
Examples of the lower alkylol in lower alkylol acrylamide or lower alkylol methacrylamide include methylol, ethylol, propyrrole, and butyrol.

In the composition of the present invention, an unsaturated acrylic urethane oligomer is used as component (C). This urethane oligomer contains the component (A) and (B).
) components are desirable, and examples of such compounds include diol compounds such as diethylene glycol, 1,6-hexanediol, and 1,3-dimethylol-2-propionic acid, and dicarboxylic acids such as adipic acid. First, a polyester oligomer is formed by reacting with the polyester oligomer, and then a diisocyanate compound such as xylylene diisocyanate is reacted with the two hydroxyl groups at the ends of this polyester oligomer, and then the isocyanate at the ends of this reaction product is reacted with a diisocyanate compound such as xylylene diisocyanate. Examples include unsaturated acrylic urethane oligomers obtained by reacting 2-hydroxyethyl methacrylate with 2-hydroxyethyl methacrylate.

There are no particular limitations on the photopolymerization initiator used as component (D) in the composition of the present invention, and from among those conventionally used in photopolymerizable resin compositions,
Any one can be selected and used. Examples of the photopolymerization initiator include benzophenone derivatives such as benzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-alkoxybenzophenone, benzoin derivatives such as benzoin, benzoin isopropyl ether, and benzoin methyl ether, anthraquinone, and 2-methyl. Examples include anthraquinone derivatives such as anthraquinone and 2-ethylanthraquinone. These photopolymerization initiators may be used alone or in combination of two or more.

Regarding the blending ratio of each component in the composition of the present invention, for 100 parts by weight of component (A), 10 to 200 parts by weight of component (B), 5 to 200 parts by weight of component (C), and 100 to 200 parts by weight of component (D). ) is preferably blended in a proportion of 0.1 to 10 parts by weight. If the amount of component (B) is less than 10 parts by weight, the sensitivity will be low, the exposure time will be long, and the mechanical strength and water resistance of the resulting printing plate will be insufficient due to the low crosslinking density. If the amount exceeds 1 part by weight, the surface of the photosensitive resin layer becomes sticky, resulting in poor adhesion to the negative film, which tends to reduce the reproducibility of the resulting relief.

Furthermore, if the amount of component (C) is less than 5 parts by weight, the flexibility will be poor and there is a risk of chipping of the plate during printing, while if it exceeds 200 parts by weight, it will not be compatible with component (A). There is a tendency for insoluble substances to precipitate on the surface.

On the other hand, if the amount of component (D) is less than 0.1 part by weight, the sensitivity will be low and exposure will take a long time, and if it exceeds 10 parts by weight, no improvement in sensitivity will be seen in relation to the amount. , it becomes economically disadvantageous.

The preferred blending ratio of each of these components is (
Component (B) is 30 to 10 parts by weight for 100 parts by weight of component A).
0 parts by weight, 20 to 100 parts by weight of component (C), and 1 to 5 parts by weight of component (D).

A photopolymerizable monomer may be added to the photosensitive resin composition of the present invention, if desired. This photopolymerizable monomer is an addition polymerizable compound having at least one ethylenically unsaturated group and is compatible with other components.

Examples of such photopolymerizable monomers include acrylic esters or methacrylic esters of polyhydric alcohols, glycerin diacrylate or dimethacrylate, diethylene glycol monoacrylate or monomethacrylate, diethylene glycol diacrylate or dimethacrylate, and diethylene glycol diacrylate or dimethacrylate. Ethylene glycol diacrylate or dimethacrylate, hexanediol diacrylate or dimethacrylate, trimethylolpropane triacrylate or trimethacrylate, pentaerythritol triacrylate or trimethacrylate, pentaerythritol tetraacrylate or tetramethacrylate, or epoxy compounds and acrylic or methacrylic acid addition reaction product of a compound having a carboxyl group and glycidyl acrylate or addition reaction product of glycidyl methacrylate; addition reaction product of a compound having a primary or secondary amino group and glycidyl acrylate or glycidyl methacrylate. Addition reaction products, acrylamide compounds such as acrylamide, methacrylamide, methylenebisacrylamide, methylenebismethacrylamide, diacetone acrylamide, triacrylformal, unsaturated compounds obtained by addition reaction between ethylenically unsaturated compounds having a hydroxyl group and isocyanates. Examples include saturated urethane compounds. These ethylenically unsaturated compounds may be used alone or in combination of two or more. The addition ratio of the photopolymerizable monomer is preferably within a range of not exceeding 100 parts by weight per 100 parts by weight of component (A). If it exceeds 100 parts by weight, the effects of the present invention may not be fully achieved, which is not preferable.

Furthermore, in the present invention, thermal polymerization inhibitors, colorants such as dyes and pigments, plasticizers, surfactants, etc., which are conventionally used in photopolymerizable resin compositions, may be appropriately blended within the range that does not cause any hindrance. It can also be used as

The photosensitive resin composition of the present invention is prepared by homogeneously mixing the required amounts of the above components (A), (B), (C), and (D), and various additive components used as desired. It can be prepared by In order to create a printing plate material using the photosensitive resin composition of the present invention prepared in this way, for example, a known method such as calendering, coating, compression molding, extrusion molding, etc. is applied to the support. What is necessary is to form the sheet into a sheet having a uniform thickness and form a photosensitive layer thereon. As the support, metal plates such as aluminum, steel, stainless steel, zinc, and magnesium, and sheets of synthetic resins such as polyethylene terephthalate, polypropylene, and cellulose derivatives are generally used to improve dimensional accuracy and mechanical strength. It is preferable to do so. When such a support is used, an adhesive layer, an antihalation layer, or an antihalation layer and adhesive layer may be provided between the photosensitive resin layer and the support, if necessary.

[0027]

Effects of the Invention The negative photosensitive resin composition of the present invention can be completely water-developable by using a specific vinyl alcohol polymer, urea derivative, unsaturated acrylic urethane oligomer, and photopolymerization initiator. , and can provide a printing plate with excellent water resistance and printability, and is particularly suitable for use as a negative photosensitive resin composition for letterpress printing.

[0028]

EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

Production Example 1 Production of polyvinyl alcohol A-1 etherified with N-methylolacrylamide Polyvinyl acetate 100 with a degree of polymerization of 500 and a degree of saponification of 80%
100 parts by weight of water and 20 parts by weight of methyl alcohol were added to the parts by weight, and the mixture was maintained at 80°C to dissolve. To this, 30 parts by weight of N-methylolacrylamide, 0.1 part by weight of methylhydroquinone and 1 part by weight of 85% by weight phosphoric acid were added,
After reacting at 80°C for 3 hours, the reaction product was neutralized with ammonia, added to 1000 parts by weight of acetone with vigorous stirring, and the deposited precipitate was filtered and dried to obtain polyvinyl etherified with N-methylolacrylamide. Alcohol A-1 was obtained.

Production Example 2 Production of polyvinyl alcohol A-2 etherified with N-methylolacrylamide Polyvinyl acetate 100 with a degree of polymerization of 500 and a degree of saponification of 88%
100 parts by weight of water and 20 parts by weight of methyl alcohol were added to the parts by weight, and the mixture was maintained at 80°C to dissolve. To this, 35 parts by weight of N-methylolacrylamide, 0.1 part by weight of methylhydroquinone and 1 part by weight of 85% by weight phosphoric acid were added,
After reacting at 80°C for 3 hours, it was neutralized with aqueous ammonia,
The reactant was added to 1000 parts by weight of acetone with vigorous stirring, and the precipitate was filtered and dried to obtain polyvinyl alcohol A-2 etherified with N-methylolacrylamide.

Production Example 3 Production of condensate B-1 of dimethylolacrylamide and urea 0.07 parts by weight of methylhydroquinone and 1.4 parts by weight of ammonium chloride were dissolved in 30 parts by weight of water, and 60 parts by weight of urea was dissolved in this.
138 parts by weight of N-methylol acrylamide were added, the reaction was carried out for 2 hours while maintaining the temperature at 80°C, the reactant was added to 1000 parts by weight of acetone with vigorous stirring, and the precipitate precipitated was filtered and dried. Target condensate B
-1 was obtained.

Production Example 4 Production of condensate B-2 of dimethylol urea dimethyl ether and N-methylol acrylamide 0.025 parts by weight of methylhydroquinone was dissolved in 10 parts by weight of water, and 74 parts by weight of dimethylol urea dimethyl ether was dissolved in 10 parts by weight of water.
parts by weight, 202 parts by weight of N-methylol acrylamide,
After adding 2 parts by weight of ammonium chloride and reacting at 80°C for 2 hours, the reactant was added to 1000 parts by weight of acetone with vigorous stirring, and the precipitate precipitated was filtered and dried to obtain the target condensate B. -2 was obtained.

Production Example 5 Production of unsaturated acrylic urethane oligomer C-1 Diethylene glycol, 1,6-hexanediol, dimethylolpropionic acid and adipic acid were mixed in a molar ratio of 2:5:3.
:7 to form a polyester, and then xylylene diisocyanate 2 to 1 mole of the polyester.
An unsaturated acrylic urethane oligomer C-1 was obtained by reacting 2 moles of 2-hydroxyethyl methacrylate and then adding 2 moles of 2-hydroxyethyl methacrylate thereto.

Example 1 100 parts by weight of A-1 obtained in Production Example 1, 100 parts by weight of B-2 obtained in Production Example 4, C-1 obtained in Production Example 5
50 parts by weight, pentaerythritol triacrylate 2
0 parts by weight, 3 parts by weight of benzyl dimethyl ketal, 0.05 parts by weight of methylhydroquinone and 150 parts by weight of water.
The solution was uniformly dissolved while stirring in a flask kept at 40°C, and then cast onto an antihalation layer provided on a 0.17 mm thick iron substrate.
After drying for 5 hours, a negative photosensitive resin layer having a dry film thickness of 0.4 mm was obtained. On top of this layer is a test negative film and No. Step 2 Tablets (manufactured by Kodak Corporation) are stacked and vacuum-adhered, and a chemical lamp [F manufactured by Toshiba Corporation] is applied.
After exposure for 4 minutes from a distance of 2.4 cm using [Model L40BL], incubate with warm water at 30°C for 1 minute and 30 minutes using a brush eluator.
It took a few seconds to wash out the unexposed areas. The film was then dried at 100° C. for 5 minutes, and further exposed to light using the chemical lamp described above for 5 minutes.

As a result, No. The number of insolubilization stages using step 2 tablets was 16. Further, the image reproducibility was as shown in Table 1. When this plate was immersed in water at 25° C. for 2 hours, it was confirmed that the relief surface swelled by only 5% in thickness, and the image area was solid and had excellent water resistance. Furthermore, this plate is rotated 180°
The plate did not break even when bent, and was highly flexible. On the other hand, when this plate was printed using a water-based emulsion ink on a newspaper letterpress rotary press, sharp images were maintained for more than 3 hours even when printing at a speed of 100,000 copies per hour.

Comparative Examples 1 to 5 Printing plates were prepared in the same manner as in Example 1 using negative photosensitive resin compositions having the compositions shown in Table 1, and their performance was evaluated. The results are shown in Table 1. From these results, (A)
Each of the components, (B) component, and (C) component has water resistance,
It was confirmed that this is important in producing flexible printing plates.

[Table 1] (Notes) 1) Regarding the condition of the image area after immersion in water at 25°C for 2 hours, 〇 indicates that there is no change at all, △ indicates that some of the fine lines have swelled and the relief has collapsed, and × indicates that the relief has collapsed. Each represents a situation in which the relief is completely swollen and does not retain its original shape. 2) Flexibility indicates the degree of cracking when bent at 180°, with 〇 representing items that do not break and × representing items that will break. 3) Kodak Step Tablet No. It represents the number of insolubilization stages when 2 is used. 4) Represents the limit value at which a halftone dot density of 65 lines/inch can be reproduced. 5) Represents the minimum reproducible line width (μm). 6) Depth of 0.5mm white area after plate making (μm)
represents.

Example 2 100 parts by weight of A-2 obtained in Production Example 2, 100 parts by weight of B-1 obtained in Production Example 3, C-1 obtained in Production Example 5
40 parts by weight, 2 parts by weight of benzyl methyl ketal, 0.05 parts by weight of methylhydroquinone and 130 parts by weight of water.
The solution was uniformly dissolved while stirring in a flask kept at 40°C, and then cast to a certain thickness onto the antihalation layer provided on the iron substrate, and then dried at 40°C for 15 hours. A negative photosensitive resin layer having a film thickness of 0.5 mm was obtained. On top of this layer is a test negative film and No.
Step 2 tablets (manufactured by Kodak Corporation) were stacked and vacuum evaporated, and a chemical lamp [FL40B manufactured by Toshiba Corporation] was applied.
After exposure for 5 minutes from a distance of 2.4 cm using [L-type], the unexposed areas were washed out with warm water at 30° C. for 2 minutes using a brush type eluator. The film was then dried at 100° C. for 5 minutes, and further exposed to light using the chemical lamp described above for 10 minutes.

As a result, No. The number of insolubilization stages using step 2 tablets was 15. Further, halftone dots in the 2% highlight portion with a minimum line width of 30 μm and 65 lines/inch remained. Furthermore, when this plate was immersed in water at 25° C. for 2 hours, the condition of the image area remained unchanged, and the plate did not crack even when bent 180°. Also, 0.5mm
The depth of the white part after plate making was 250 μm.

Claims (1)

[Claims] Claim 1: (A) a vinyl alcohol polymer etherified with lower alkylol acrylamide or lower alkylol methacrylamide; (B) urea, thiourea, or lower alkylated, lower alkylolated or lower alkyl thereof; A negative photosensitive resin composition comprising a condensate of a lower alkylol derivative and a lower alkylol acrylamide or a lower alkylol methacrylamide, (C) an unsaturated acrylic urethane oligomer, and (D) a photopolymerization initiator. .