JP2967790B2 - Negative photosensitive resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a novel negative photosensitive resin, and more particularly, it is rich in flexibility such that it does not crack when dried or used in a printing machine having a small cylinder diameter. The present invention also relates to a negative photosensitive resin capable of providing a relief printing plate having excellent printing durability.

[0002]

2. Description of the Related Art Conventionally, negative photosensitive resins used in the production of printing plates include alcohol-soluble, alkali-soluble, organic solvent-soluble and water-soluble resins. In recent years, attention has been paid to a water-soluble type in view of safety of the treatment process, no necessity of waste liquid treatment, and easy management of work health.

As the water-soluble negative photosensitive resin for producing a printing plate, for example, a resin composed of polyvinyl alcohol, acrylamides and a photosensitizer (JP-B-39-259)
No. 41), a composition comprising a grafted product of polyvinyl alcohol and a photosensitizer (Japanese Patent Publication No. 44-28275), and a composition using an ester of polyvinyl alcohol and an unsaturated carboxylic acid as a photosensitive component (Japanese Patent Publication No. 48-6962). Gazettes) and those comprising a combination of polyvinyl alcohol and acrylates such as β-hydroxyethyl methacrylate (U.S. Pat. No. 3,801,328).

However, a water-soluble negative photosensitive resin composed of a combination of these polyvinyl alcohols and a resin having a photoreactive group has low developability, and furthermore, usually contains polyvinyl alcohol or a derivative thereof and a photosensitive agent. Due to the low compatibility with the unsaturated compound used, it is inevitable that the types of combinations are limited, and therefore it is difficult to obtain a printing plate excellent in flexibility and printing durability, and furthermore, the obtained printing Plates have drawbacks such as being easily cracked during drying in winter or the like.

Further, a composition comprising a combination of a water-soluble nylon and a photosensitive agent has been proposed (Japanese Patent Publication No. 53-20 / 1973).
No. 82), this composition has poor compatibility between the water-soluble nylon and the photosensitive agent and is not completely water-soluble, so that insoluble substances precipitate in the used developer after the development processing. Thus, there is a possibility that the pipes and the like may be clogged, and there is a disadvantage that acetic acid or the like must be added to react with the precipitate and be removed.

[0006] The present inventors have proposed polyvinyl alcohol and a polycondensate having compatibility with polyvinyl alcohol, as an improvement over the above-mentioned drawbacks of the conventional water-soluble negative photosensitive resin. For example, a photosensitive resin composition comprising a polycondensate of alkylol urea and N-alkylol acrylamide or a polycondensate of urea and formaldehyde and addition condensation of N-alkylol acrylamide has been proposed. JP-B-54-3790). However, although this composition can provide a printing plate of remarkably high quality as compared with the conventional water-soluble negative photosensitive resin, the prepared relief image tends to be hard, and the plate is easily broken, It was not always satisfactory.

On the other hand, the present inventors have further proposed a water-soluble resin,
A photosensitive resin composition comprising a photopolymerization initiator and a reaction product of polyglycerin and a photopolymerizable compound having an ethylenically unsaturated bond has been proposed (JP-A-60-101531). However, in this composition, although the resulting printing plate is hard to break, when used in a printing machine having a small-diameter cylinder such as a label printing machine,
There is a problem that the occurrence of cracks in the printing plate cannot be completely suppressed.

[0008]

SUMMARY OF THE INVENTION The present invention overcomes such disadvantages of the conventional water-soluble negative photosensitive resin,
Even when used for drying or printing machines with small-diameter cylinders,
It is an object of the present invention to provide a negative photosensitive resin which can provide a photosensitive resin plate which is free from cracks and has excellent flexibility and excellent printing durability.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to develop a negative photosensitive resin which is flexible and can provide a printing plate excellent in printing durability and printability. It has been found that a specific vinyl alcohol-based polymer, a urea derivative, a polyethylene glycol having an unsaturated group at a terminal, and a photosensitive resin containing a photopolymerization initiator can achieve the object. Thus, the present invention has been completed.

That is, the present invention relates to (A) a vinyl alcohol polymer etherified with lower alkylol acrylamide or lower alkylol methacrylamide having an average degree of polymerization of 200 to 2,000, (B) urea, thiourea, Lower alkylated, lower alkylolated or lower alkyl lower alkylolated derivative and lower alkylol acrylamide or lower alkylol methacrylamide condensate; (C) polyethylene glycol having 7 to 25 carbon atoms with acrylic acid or methacrylic acid And (D) a photopolymerization initiator.

In the photosensitive resin of the present invention, a vinyl alcohol polymer etherified with lower alkylol acrylamide or lower alkylol methacrylamide is used as the component (A). Examples of the lower alkylol of the lower alkylol acrylamide or the lower alkylol methacrylamide in the vinyl alcohol polymer include methylol, ethylol, propylol, and butyrol. The vinyl alcohol polymer may be polyvinyl alcohol obtained by completely saponifying polyvinyl acetate, or may be a partially saponified product, that is, a vinyl alcohol copolymer having a vinyl alcohol unit. When a copolymer is used, a copolymer containing at least 60 mol% of a vinyl alcohol unit is desirable. Examples of the copolymer component of the copolymer include vinyl acetate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-
Examples include methylol acrylamide, N-methylol methacrylamide, styrene, ethylene, propylene, maleic anhydride, acrylonitrile, methacrylonitrile, acrylate, methacrylate, and the like.

This vinyl alcohol-based polymer must be water-soluble, and has an average degree of polymerization of 200 to 200.
0, preferably in the range of 300 to 1000 is used.

The etherified vinyl alcohol-based polymer used as the component (A) in the present invention can be prepared by adding the vinyl alcohol-based polymer in the presence of an acidic catalyst such as an inorganic acid, a sulfonic acid derivative, and an ammonium halide. With lower alkylol acrylamide or lower alkylol methacrylamide. Further, as the reaction method, a method of reacting the reaction components in an aqueous medium may be used,
After uniformly mixing the reaction components in an aqueous medium, the solvent may be removed, and the resulting mixture may be reacted by heating.

The etherified vinyl alcohol polymer thus obtained preferably contains at least 50 mol% of a vinyl alcohol unit, and the photosensitive resin obtained by using this polymer has sufficient sensitivity. In addition, a printing plate having satisfactory flexibility, printing durability and printability can be provided.

In the photosensitive resin of the present invention, urea, thiourea or lower alkylation thereof may be used as component (B).
A condensate of a lower alkylol or a lower alkyl lower alkylol derivative and a lower alkylol acrylamide or a lower alkylol methacrylamide is used.

Examples of the condensate include polycondensation of an alkylol derivative or an alkylated alkylol derivative of urea or thiourea with N-alkylolacrylamide or N-alkylolmethacrylamide in the presence of an acid or ammonium salt. Or reacting urea or thiourea with formaldehyde to form a linear condensation polymer, which is then grafted with N-alkylolacrylamide or N-alkylolmethacrylamide in the presence of an acid or ammonium salt. Reaction product (Japanese Patent Publication No. 54-3790) or urea, thiourea or their alkyl derivatives and N-alkylolacrylamide or N-alkylolmethacrylamide in an acid in water or a hydrophilic organic solvent. Or use an alkali catalyst to inhibit thermal polymerization Under the presence, and the like those obtained by reacting under stirring for 1 to 5 hours at a temperature range of 60 to 95 ° C. (KOKOKU 1-48528 Patent Publication). Here, as the lower alkyl in the lower alkylated, lower alkylolated or lower alkyl lower alkylolated derivative, methyl, ethyl, propyl, butyl, etc., and as the lower alkylol, methylol, ethylol, propylol, butyrol, etc. Examples of the lower alkylol of lower alkylol acrylamide or lower alkylol methacrylamide include methylol, ethylol, propylol, and butyrol.

In the photosensitive resin of the present invention, a component obtained by diesterifying hydroxyl groups at both ends of polyethylene glycol having 7 to 25 carbon atoms with acrylic acid or methacrylic acid is used as the component (C). If the polyethylene glycol has less than 7 carbon atoms, it will not be water-soluble and will have poor compatibility with the component (A), and will have a brittleness exceeding 25, resulting in poor flexibility. That is, if the carbon number is outside the above range, a photosensitive resin which sufficiently satisfies all of the flexibility, printing durability and printability cannot be obtained. The preferred number of carbon atoms is selected in the range of 10-20.

In the photosensitive resin of the present invention, the photopolymerization initiator used as the component (D) is not particularly limited, and any one can be selected from those conventionally used in photopolymerizable resins. Can be 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-methylanthraquinone And anthraquinone derivatives such as 2-ethylanthraquinone. One of these photopolymerization initiators may be used,
Two or more kinds may be used in combination.

The mixing ratio of each component in the photosensitive resin of the present invention is based on 100 parts by weight of component (A).
Component (B) is 1 to 100 parts by weight, and component (C) is 5 to 10 parts by weight.
It is preferable to mix 0 part by weight and the component (D) in a ratio of 0.1 to 10 parts by weight. If the amount of the component (B) is less than 1 part by weight, the sensitivity is low, the exposure time is long, and the mechanical strength and printing durability of the printing plate obtained due to low crosslinking density are insufficient. If the amount exceeds 100 parts by weight, the reproducibility of the obtained relief is deteriorated and the water resistance is lowered.

If the amount of the component (C) is less than 5 parts by weight, the flexibility is poor and the plate may be chipped during printing. If the amount exceeds 100 parts by weight, the compatibility with the component (A) may occur. , And the insoluble matter tends to precipitate on the surface.

On the other hand, when the amount of the component (D) is less than 0.1 part by weight, the sensitivity is low and the exposure takes a long time. When the amount exceeds 10 parts by weight, the sensitivity is not improved for the amount. At an economic disadvantage.

The preferred mixing ratio of each of these components is as follows:
Component (B) is 5 to 70 parts by weight based on 100 parts by weight of component (A).
Parts by weight, the component (C) is selected in the range of 10 to 50 parts by weight, and the component (D) is selected in the range of 1 to 5 parts by weight.

A photopolymerizable monomer can be added to the photosensitive resin of the present invention, if desired. The 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 acid esters or methacrylic acid esters of polyhydric alcohols, glycerin diacrylate or dimethacrylate, diethylene glycol monoacrylate or monomethacrylate, diethylene glycol diacrylate or dimethacrylate, trimethacrylate. Ethylene glycol diacrylate or dimethacrylate, hexanediol diacrylate or dimethacrylate, trimethylolpropane triacrylate or trimethacrylate, pentaerythritol triacrylate or trimethacrylate, pentaerythritol tetraacrylate or tetramethacrylate, or epoxy compound and acrylic acid or methacrylic acid Addition reaction product, a compound having a carboxyl group and Addition products of glycidyl acrylate or glycidyl methacrylate, addition products of compounds having a primary or secondary amino group and glycidyl acrylate or glycidyl methacrylate, acrylamide, methacrylamide, methylenebis Examples include acrylamide compounds such as acrylamide, methylenebismethacrylamide, diacetone acrylamide, and triacrylformal, and unsaturated urethane compounds obtained by an addition reaction of an ethylenically unsaturated compound having a hydroxyl group with isocyanate. These ethylenically unsaturated compounds may be used alone or in combination of two or more. It is preferable that the addition ratio of the photopolymerizable monomer is not more than 100 parts by weight based on 100 parts by weight of the component (A). If the amount exceeds 100 parts by weight, the effect of the present invention may not be sufficiently achieved, which is not preferable.

Further, in the present invention, a thermal polymerization inhibitor, a coloring agent such as a dye or a pigment, a plasticizer, a surfactant, etc., which are conventionally used in a photopolymerizable resin, are appropriately compounded within a range that does not hinder. Can also be used.

The photosensitive resin of the present invention is prepared by uniformly mixing the required amounts of the above-mentioned components (A), (B), (C), (D) and various additives used as required. Can be prepared. In order to prepare a printing plate using the photosensitive resin of the present invention thus prepared, for example, calendering, coating, compression molding, extrusion molding and the like on a support may be performed using a known method. And a photosensitive layer may be formed. As the support, generally, aluminum, steel, stainless steel, in order to improve dimensional accuracy and mechanical strength,
It is preferable to use a metal plate of zinc or magnesium, or a sheet of a synthetic resin such as polyethylene terephthalate, polypropylene, or a cellulose derivative. When such a support is used, an adhesive layer, an antihalation layer, or an antihalation layer / adhesive layer can be provided between the photosensitive resin layer and the support as necessary.

[0027]

The negative photosensitive resin of the present invention has high flexibility by using a specific vinyl alcohol polymer, a urea derivative, polyethylene glycol having unsaturated groups at both terminals and a photopolymerization initiator. It can provide a printing plate excellent in printing durability and printability, and is particularly suitably used as a negative photosensitive resin for letterpress printing.

[0028]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Production Example 1 Production of polyvinyl alcohol A-1 etherified with N-methylolacrylamide Polyvinyl acetate 100 having a polymerization degree of 500 and a saponification degree of 80%
100 parts by weight of water and 20 parts by weight of methyl alcohol were added to the parts by weight and dissolved at 80 ° C. To this were added 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,
After reacting at 80 ° C. for 3 hours, the mixture was neutralized with ammonia, and the reaction product was added to 1,000 parts by weight of acetone with vigorous stirring, and the deposited precipitate was filtered and dried, and polyvinyl ether etherified with N-methylolacrylamide was used. Alcohol A-1 was obtained.

Production Example 2 Production of polyvinyl alcohol A-2 etherified with N-methylolacrylamide Polyvinyl acetate 100 having a polymerization degree of 500 and a saponification degree of 88%
100 parts by weight of water and 20 parts by weight of methyl alcohol were added to the parts by weight and dissolved at 80 ° C. To this were added 35 parts by weight of N-methylolacrylamide, 0.1 parts by weight of methylhydroquinone and 1 part by weight of 85% by weight phosphoric acid,
After reacting at 80 ° C for 3 hours, neutralize with ammonia water,
The reaction product was added to 1,000 parts by weight of acetone with vigorous stirring, and the deposited precipitate was filtered and dried to obtain polyvinyl alcohol A-2 etherified with N-methylolacrylamide.

Production Example 3 Production of condensate B-1 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 dimethylol urea dimethyl ether 74 was added thereto.
Parts by weight, N-methylol acrylamide 202 parts by weight,
After adding 2 parts by weight of ammonium chloride and reacting at 80 ° C. for 2 hours, the reaction product was added to 1,000 parts by weight of acetone with vigorous stirring, and the deposited precipitate was filtered and dried to obtain the desired condensate B-. 1 was obtained.

Production Example 4 Condensate B-2 of urea and N-methylolacrylamide
Production of 0.07 parts by weight of methylhydroquinone and 1.4 parts by weight of ammonium chloride were dissolved in 20 parts by weight of water.
After adding 138 parts by weight of N-methylolacrylamide and reacting for 2 hours while maintaining the temperature at 80 ° C., the reaction product was added to 1,000 parts by weight of acetone while vigorously stirring, and the deposited precipitate was filtered and dried. Thus, the desired condensate B-2 was obtained.

Example 1 100 parts by weight of A-1 of Production Example 1, B-1 of Production Example 3
20 parts by weight, 15 parts by weight of polyethylene glycol diacrylate having 14 carbon atoms, 3 parts by weight of benzyl methyl ketal, 0.05 parts by weight of methylhydroquinone, and 150 parts by weight of water were uniformly dissolved in a flask kept at 90 ° C. while stirring. The solution was cast on a polyethylene terephthalate film having a thickness of 188 μm, on which an antihalation layer was provided so as to have a uniform thickness, and then dried at 40 ° C. for 20 hours to obtain a film thickness of 0.64 mm upon drying. Of a negative photosensitive resin layer was obtained. On this layer, a negative film for test and 2 Step Tablet (Kodak)
Are exposed to each other for 4 minutes from a distance of 2.4 cm using a chemical lamp (FL40BL type, manufactured by Toshiba Corporation), and then exposed to warm water at 30 ° C. for 2 minutes using a brush-type dissolution machine. The exposed area was washed out. Next, it was dried at 100 ° C. for 5 minutes, and further exposed to light for 5 minutes using the above-mentioned chemical lamp.

As a result, no. The number of stages of insolubilization using the step tablet No. 2 was 14. In addition, a halftone dot of a 2% highlight part of a minimum line width of 30 μm and 65 lines / inch remained, and the depth of the thin line of 0.5 mm was 255 μm. This plate is used as a label printing machine (model A-100 manufactured by FSK)
50,000 copies were printed.
On the other hand, when the tensile strength and the elongation were measured for a sample in which only the photosensitive resin layer was entirely exposed, the tensile strength was 5.8 kg / m ^{2 and the} elongation was 150%.

Comparative Examples 1-4 Using a negative photosensitive resin having the composition shown in Table 1, a printing plate was prepared in the same manner as in Example 1, and its performance was evaluated. Table 1 shows the results. From these results, it was confirmed that each of the component (A), the component (B), and the component (C) is important in producing a printing plate having water resistance and flexibility.

[Table 1] (Note) 1) Polyethylene glycol having 14 carbon atoms was used. 2) Kodak's Step Tablet No. Indicates the number of insolubilization stages when 2 is used. 3) The limit value at which the halftone dot density of 65 lines / inch is reproduced. 4) Represents the minimum reproducible line width. 5) Depth after development of 0.5 mm white portion.

Example 2 100 parts by weight of A-2 of Production Example 2, B-2 of Production Example 4
30 parts by weight, 30 parts by weight of polyethylene glycol diacrylate having 24 carbon atoms, 2 parts by weight of benzyl methyl ketal, 0.05 parts by weight of methylhydroquinone, and 150 parts by weight of water were uniformly dissolved in a flask kept at 90 ° C. while stirring. The solution was cast on a polyethylene terephthalate film having a thickness of 250 μm on which an antihalation layer was provided so as to have a uniform thickness, and then dried at 40 ° C. for 20 hours to form a film having a dry thickness of 0.69 mm. Of a negative photosensitive resin layer was obtained. This plate was made in the same manner as in Example 1; The number of insolubilization stages was 14 using the 2 step tablets. Also, a minimum line width of 30 μm,
Halftone dots of 2% highlights of 65 lines / inch remained, and printing was performed by a printing machine. As a result, 50,000 copies of a print faithful to the film could be obtained.

──────────────────────────────────────────────────の Continuation of the front page (56) References JP-A-64-29836 (JP, A) JP-B Hei 1-48528 (JP, B2) JP-B Showa 54-3790 (JP, B2) JP-B Showa 49- 5923 (JP, B1) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03F 7/032 G03F 7/027

Claims (1)

(57) [Claims] (A) a vinyl alcohol polymer having an average degree of polymerization of 200 to 2,000 etherified with lower alkylol acrylamide or lower alkylol methacrylamide, (B) urea, thiourea or lower alkylation thereof. A condensate of a lower alkylolated or lower alkyl lower alkylolated derivative with a lower alkylol acrylamide or a lower alkylol methacrylamide,
A negative photosensitive resin comprising (C) a diester of polyethylene glycol having 7 to 25 carbon atoms and acrylic acid or methacrylic acid and (D) a photopolymerization initiator.