JPS6090338A - Original plate for photosensitive lithographic printing - Google Patents

Abstract

PURPOSE:To improve printing resistance and to enable use of an inexpensive flexible base by providing a layer which consists principally of the resulted product of reaction of a maleic anhydride copolymer and isocyanate compd. and which can be made hydrophilic between the base and a photosensitive layer. CONSTITUTION:A copolymer contg. maleic anhydride as a copolymerizing component (e.g.; a copolymer of styrene and maleic anhydride) and an isocyanate compd. (e.g.; toluene-2,4-diisocyanate) are dissolved in an org. solvent. Such solution is coated on a base 1 such as synthetic paper, plastic film or the like and is subjected to a heating treatment to bring the maleic anhydride copolymer and the isocyanate compd. into crosslindking reaction, thereby forming a layer 2 which can be made hydrophilic. A photosensitive layer 3 contg. a photosensitive material such as a photosetting diazo resin, a photosolubilizing orthonaphtoquinone diazide resin is provided thereon by which the intended original plate for photosensitive lithographic printing is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a photosensitive lithographic printing original plate, and more particularly to a photosensitive lithographic printing original plate having a layer made of a specific resin on a support.

Conventional technology Conventionally, photosensitive planographic printing plates (so-called PS plates) are
A support whose surface is made hydrophilic by mechanically graining the surface of a metal plate such as an aluminum plate, chemically treating it with an aqueous solution of helium silicate or zirconium fluoride, or anodizing it. Those in which a photosensitive layer made of a photosensitive resin, diazo resin, or orthoquinone diazide compound is provided thereon have been put into practical use and are widely used. With such PS plates, the photosensitive layer in the non-image area is removed by image exposure and development, and printing takes advantage of the hydrophilicity of the substrate surface and the lipophilicity (ink affinity) of the photosensitive layer remaining in the image area. It is done.

Hydrophilically treated metal plates are excellent in terms of strength as a support and maintaining hydrophilicity during printing, and can provide high printing durability, but are expensive and lack flexibility, so it is difficult to handle the plate. There are drawbacks such as restrictions on the size of the plate making device and the inability to downsize the plate making device.

Therefore, there is a method in which a hydrophilic resin layer is provided on an inexpensive and flexible support such as water-resistant paper, plastic film, or synthetic paper, and a photosensitive layer is formed thereon.

However, the resins used for the hydrophilic resin layer here include, for example, polyvinyl alcohol, gelatin, casein, gum arachia, starch, cellulose derivatives (ruboxymethylhyululose, hydroxyedyllerulose, etc.),
Since it is a water-soluble resin such as sodium polyacrylate, polyethylene oxide, and polyacrylamide, even though it is hydrophilic, it should be water resistant, so it may be eluted by etching solution or dampening water during plate making or printing. Smudged background and image loss are likely to occur.

In order to improve the water resistance of the hydrophilic resin layer, glyoxyl, melamine, urea, amine resins (e.g. urea formaldehyde resin, melamine formaldehyde resin) are used.
There is also a method of adding a crosslinking agent such as and curing by heating, but if you emphasize water resistance and crosslink sufficiently, the hydrophilicity will be impaired and cause staining of the background, but if you emphasize hydrophilicity, the water resistance will be insufficient. Therefore, it is extremely difficult to achieve both hydrophilicity and water resistance.

For this reason, the printing life of this type of lithographic printing original plate is several hundred.
The number is approximately 1,000 sheets.

A copolymer containing maleic anhydride as one of the copolymerization components (referred to for simplicity as a maleic anhydride copolymer) is used as a resin for forming the hydrophilic resin layer of such a lithographic printing original plate. For example, in Japanese Patent Publication No. 44-6406, the acid anhydride group in a maleic anhydride copolymer is ring-opened with water to form an aqueous solution, and a polyhydroxy compound such as polyvinyl alcohol or a polyamino compound such as urea is added to crosslink and cure the solution. A hydrophilic layer is used. However, in this case, since the maleic anhydride copolymer is ring-opened by hydrolysis and used as the hydrophilic resin, it has the same drawbacks as the lithographic printing original plate using the hydrophilic resin described in 7f above.

A maleic anhydride copolymer is originally a hydrophobic resin, but when the acid anhydride group is ring-opened by hydrolysis, it becomes hydrophilic.

There is a method in which this change to hydrophilicity is performed during plate making to form a hydrophilic layer. For example, US Pat. No. 2,772,972 discloses a lithographic printing original plate in which a layer mainly composed of an alkylvinyl I-thyl-maleic anhydride copolymer is provided on a support, and a photosensitive layer is provided thereon. Ma Iζ Japanese Patent Publication No. 1983
Publication No. 98395 discloses a printing original plate in which a layer of an aggregate of an al-4-ruhinyl-teru-maleic anhydride copolymer and a water-insoluble polyvalent metal compound is similarly provided between a support and a photosensitive layer. ing. When these are treated with an alkaline aqueous solution after or during development of the photosensitive layer, the acid anhydride group in the exposed part of the layer containing the maleic anhydride copolymer in the non-image area undergoes ring-opening and changes to hydrophilicity. A hydrophilic layer is formed.

In this way, printing original plates in which a hydrophobic resin layer is made hydrophilic during plate making are easier to coat onto hydrophobic supports such as plastic films than parent layers originally formed using hydrophilic resins. In addition, since only the non-image areas are made hydrophilic, there is an advantage that the adhesion with the photosensitive layer is good and the image is less likely to be lost. In both cases, the water resistance of the hydrophilic layer formed after hydrophilic treatment is insufficient, and the layer swells and is destroyed during printing, so high printing durability cannot be expected, and it is difficult to print several thousand sheets. is the limit.

Purpose The purpose of the present invention is to provide a photosensitive lithographic printing original plate that exhibits printing durability comparable to that of conventional PS plates by improving the water resistance of the hydrophilic layer of such a lithographic printing plate. ,
Another object of the present invention is to provide a photosensitive lithographic printing original plate using an inexpensive and flexible support such as paper, plastic film, or synthetic paper.

Structure The inventor of the present invention considered that the material should easily change from hydrophobic to hydrophilic during plate making, and at the same time be water resistant.
As a result of examining various materials, we found that the layer formed by the crosslinking reaction product of maleic anhydride copolymer and isocyanate compound has a surface that can be easily made hydrophilic by an aqueous alkaline solution, and is resistant to swelling and has high water resistance. I discovered that.

In the present invention, a layer containing a reaction product of a copolymer containing maleic anhydride as one copolymerization component and an isocyanate compound as a main component is arranged on a support, and a photosensitive layer is provided on top of the layer. This is a photosensitive lithographic printing original plate that is characterized by the following.

The basic structure of the photosensitive lithographic printing original plate of the present invention is shown in FIG. In the figure, 1 is a support, 2 is a layer mainly composed of a reaction product of a maleic anhydride copolymer and an isocyanate compound, and 3
is the photosensitive layer. Here, layer 2 is originally a hydrophobic layer, but when treated with an alkaline aqueous solution, the acid anhydride groups on and near the surface undergo hydration and change to hydrophilicity. Therefore, layer 2 will be referred to as the hydrophilizable layer in the middle of this specification.

Examples of the maleic anhydride copolymer used in forming the hydrophilizable layer of the printing plate of the present invention include methyl vinyl ether, ethyl vinyl ether, 2-chlorovinylethyl ether, propyl vinyl ether, isobutyl vinyl ether, 2- Copolymers of lower alkyl vinyl ethers such as methoxyethyl vinyl ether and maleic anhydride, copolymers of styrene and maleic anhydride,
Examples include copolymers of ethylene and maleic anhydride, and copolymers of vinyl YF acid and maleic anhydride. Furthermore, these maleic anhydride copolymers in which some of the acid anhydride rings are open can also be used.

Isocyanate compounds used as crosslinking agents include, for example, toluene-2,4-diisocyanate, toluene-2,4-diisocyanate, and toluene-2,4-diisocyanate.
2,6-diisocyanate, naphthylene-1,5-diisocyanate, 3,3-dimethylbiphenyl-4,4
'-diisocyanate, triphenylmethane-4,4-
Aromatic polyisocyanates such as 24"-triisocyanate, tris-(p-isocyanate phenyl) thiopht-sulfite, polymethylene polyphenyl isocyanate, xylene diisocyanate, or hexyl methylene diisocyanate 1-, trimethylhexamethylene diisocyanate 1, aliphatic polyisocyanates such as isoborone diisocyanate 1 or dimers thereof,
Trimers etc. can be used.

Examples of the support used in the printing original plate of the present invention include paper, synthetic paper, plastic film, metal foil, composite materials such as metal foil and paper or plastic film,
Examples include metal plates such as iron plates, zinc plates, and aluminum plates. Among these, plastic films, synthetic papers, and the like are particularly preferred because they are easy to handle and inexpensive.

For the photosensitive layer of the printing plate of the present invention, any photosensitive material used in ordinary PS plates can be used.

There are two types of photosensitive materials: negative type and positive type.Negative types include photocurable diazo resins and photodimerized vinyl polycinnamate photosensitive resins, and positive types include commercially available solubilized photosensitive resins. Orthonaphthoquinonediazide-based photosensitive resins are representative examples.

To produce the printing original plate of the present invention, first, a hydrophilic layer is provided on a suitable support.

The hydrophilic layer is prepared by dissolving a maleic anhydride copolymer as described above in an organic solvent having no active hydrogen, such as dioxane, tetrahydrofuran, or dimethylbormamide, and adding an isocyanate compound to the solution. After coating and drying, a heat treatment is performed to cause a crosslinking reaction between the maleic anhydride copolymer and the isocyanate compound. The temperature and time of this heat treatment vary depending on the combination of maleic anhydride copolymer and isocyanate compound used, but are 80 to 200°C,
You can choose from a few minutes to a few hours. By coating the photosensitive material as described above using a suitable solvent on the hydrophilizable layer thus formed and drying it, the photosensitive lithographic printing material 1 of the present invention (previously 11 tons) is obtained.

When forming the hydrophilic 1+J functional layer, in order to promote the crosslinking reaction between the maleic anhydride copolymer and the isocyanate compound, for example, dibutyltin dilaurate, dibutyltin diacetate-1-, 2-ethylhexoate,
Titanium)-1-nozo-I・1-cyto, Al-1-tin acid, dibdelsus (2-ethylhexoate), potassium oleate, lil'l M bispea, 2-ethylhexyl ditanate, tin chloride , metal compounds such as zinc naphthenate, antishine 1-lychloride, or amines such as 1-lyl-thylamine and 1-lyethylenediamine can be added in appropriate amounts.

The hydrophilic IIJ functional layer of the present invention is mainly composed of a crosslinking reaction product of a maleic anhydride polymer and an isocyanate compound, but in order to improve the strength of the layer, other resins such as polyester resin, polyamide resin, etc. , Bolicarbonate 1
~Resin, acrylic resin, polystyrene resin, vinyl acetal resin, vinyl acetate resin, etc. can be added. However, in this case, the proportion of these resins contained in the entire layer is preferably 50% by weight or less. If it exceeds this range, the rate of hydrophilization in the hydrophilic treatment will be slow and the hydrophilicity will be insufficient, resulting in background stains on printed matter.

In addition to this, additives such as plasticizers can be added to the hydrophilic layer. Alternatively, for the purpose of improving water retention in the non-image area after hydrophilic treatment, a matting agent may be included or the surface may be mechanically matted. Examples of the matting agent include silicon dioxide, zinc oxide, titanium oxide, zirconium oxide, glass particles, alumina, clay, and polymer particles such as polymethyl methacrylate, polystyrene, and phenolic resin.

Although there are no functional restrictions on the thickness of the hydrophilic layer in the printing original plate of the present invention, about 1 to 20 μm is practically appropriate.

Plate making of the printing original plate of the present invention is carried out through an exposure step, a development step, and a hydrophilization step.

Exposure is 7i4. I) Like the 8th edition, this is done by transmission image exposure using negative or positive film, or scanning exposure using laser light.

Next, in the development step, the photosensitive layer in the non-image area is removed, and ?
31 The hydratable layer is exposed and covered. When this is immersed in an alkaline aqueous solution in the hydrophilization step, the surface of the hydrophilizable layer in the non-image area changes from hydrophobic to hydrophilic. However, if the photosensitive layer is developed with an alkaline aqueous solution, the hydrophilization process is not necessary because it is made hydrophilic at the same time as the development.
It's convenient. After the hydrophilic treatment, if necessary, the plate is washed with water and dried to obtain a good lithographic printing plate.

Examples of the alkaline solution used in the hydrophilization step include aqueous solutions of inorganic salts such as su]-lium silicate, sodium phosphate, su-lium hydroxide, potassium hydroxide, aqueous ammonia, ethanolamine, jetanolamine, etc. These are aqueous solutions containing organic amines such as triethanolamine, propatoolamine, diisopropanolamine, butanolamine, and ethylenediamine.
Furthermore, organic solvents such as ethanol, benzyl alcohol, ethylene glycol, and glycerin, surfactants, and the like are added as necessary.

The time required for hydrophilization varies depending on the composition of the hydrophilizable layer, the degree of crosslinking, the formulation of the hydrophilic treatment liquid, etc., but if appropriate combinations and conditions are selected, hydrophilization can be achieved in about 1 to 30 seconds.

The non-image area of the lithographic printing plate prepared in this manner exhibits desirable hydrophilicity. This hydrophilicity can be confirmed, for example, by measuring the contact angle with respect to water. That is, the contact angle of the surface of the hydrophilizable layer with water before being made hydrophilic is approximately 60 to 80 degrees, but after being made hydrophilic, the contact angle with water is reduced to approximately 10 to 15 degrees, indicating that the surface is highly wettable with water. It becomes. This hydrophilic culm 1 is +ul 7:
'+ '7) t' Sand grain I used in 8th edition
It is equivalent to a polished aluminum plate, and the surface is dirty.
There is enough C to give high quality prints.

In addition, this layer whose surface has been made hydrophilic does not swell even when immersed in water, and has high water resistance. During printing, the lithographic printing plate is always wet with water. Furthermore, the printing plate according to the present invention is subjected to repeated mechanical pressure due to the blanket and ink []-no, but even under these conditions, the hydrophilized layer is destroyed. Never.

In the present invention, the hydrophilic layer d3 has adhesion to a support such as a plastic film or synthetic paper and a photosensitive layer. An image is formed on the transparent resin layer.
Images are less likely to be lost.

As described above, the photosensitive lithographic printing original plate of the present invention can provide a lithographic printing plate that has excellent printing durability and can produce high-quality printed matter.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples.

Example 1 [Hydrophilizable layer coating 'a] Medyl vinyl ether-maleic anhydride copolymer (manufactured by Altrich Chemical Company) 1 part by weight 1 to 2.4-cyisocyanate-1 to 0.17 parts dilaurin Dibdeltin acid 0.02 parts by weight Tetrahydrofuran 19 parts by weight The coating solution for the hydrophilizable layer having the above composition was applied onto a polynisdel film with a thickness of 100 μm, dried at 100°C for 5 minutes, and then at 150°C for 2 hours. Heat treated to a film thickness of 3μmL
:I) Forming a hydrophilic layer I[.

Next, on top of that, [Photosensitive layer coating liquid] His 71 Nor△ bis(1,2-naphthoginone-2-diazide-〇-sulfonic acid) ester 2 parts by weight Cresol novolac resin N! Manufactured by Yei Kagaku Jogyogi: MP-703> 8 parts by weight Medil violet 0.1 parts 1 part ethylene glycol 7-noethyl ether 100 parts by weight Coat the photosensitive layer coating solution with the above composition.l'i L, 100°C
to form a photosensitive layer with a thickness of about 3 μm.
19I of the photosensitive lithographic printing original plate of the present invention.

A film original with a positive image was brought into close contact with the surface of this printing original plate, and a 45All+3, 70°
After exposure for 70 seconds from a distance of co+, metasilicic acid 1
- 5.5 parts by weight of lithium, 3.4 parts by weight of tristrium phosphate, 0.4 parts by weight of sodium hydrogen phosphate, 0.4 parts by weight, and 90.7 parts by weight of water. At the same time as removing the photosensitive layer in the non-image area, the surface of the hydrophilizable layer in the non-image area was made hydrophilic.

After washing and drying, in order to confirm hydrophilicity, the contact angle of the non-image area with water was measured to be approximately 10° (by the way, the contact angle of the surface of the hydrophilic layer before hydrophilic treatment was 65°).
)Met.

The planographic printing plate made in this way is then printed on an offset printing machine (■
Printed using Ricoh's A P-1310), the result is a clear print with no background stains or missing images.
More than ,000 pieces were obtained.

Example 2 [Hydrophilizable layer coating liquid] Styrene-anhydrous to maleic acid copolymer (manufactured by Aldrich Chemical Company) 1 part by weight Toluene-2,4-diisocyanate 0.09 parts by weight 1.4-dioxane 19 Parts by Weight A hydrophilizable layer coating solution having the above composition was applied onto a polyester film having a thickness of 100 μm, dried at 100°C for 5 minutes, and then heat-treated at 150°C for 2 hours to obtain -CI+! 419, a hydrophilizable layer of about 3 μm was formed.

Next, a photosensitive layer was formed on the tenth plate in the same manner as in Example 1 to obtain a photosensitive lithographic printing original plate of the present invention.

This printing original plate was imagewise exposed and developed in the same manner as in Example 1, and the surface of the hydrophilic layer in the non-image area was made hydrophilic.

When printing was carried out in the same manner as in Example 1 using the lithographic printing plate made in this manner, there were 4'r of background stains and missing images.
, over 50,000 clear prints11? It was done.

Example 3 [Hydrophilizable layer surface A 11 Liquid 1 Methyl vinyl ether-maleic anhydride copolymer (manufactured by Aldrich Chemical Company) 1 part by weight Diphenylmethane-4,4'-diisocyanate 0.15 parts Tetrahydrofuran 19 parts by weight The above composition The thickness of the coating liquid for the hydrophilic layer is 1o.

Coated on μn1 polyester film and heated to 100°C.
After drying for 5 minutes, heat treatment was performed at 150° C. for 2 hours to form a hydrophilic layer having a thickness of 3 μm.

Next, a photosensitive layer was formed thereon in the same manner as in Example 1 to obtain a photosensitive lithographic printing original plate of the present invention.

This printing original plate was imagewise exposed and developed in the same manner as in Example 1, and the surface of the hydrophilizable layer in the non-image area was made hydrophilic.

When printing was carried out in the same manner as in Example 1 using the lithographic printing plate prepared in this way, more than 50,000 clear printed matter without background stains or image loss were obtained.

Comparative Example 1 1 part by weight of methyl vinyl ether-maleic anhydride copolymer (Aldrich Chemical Company, 1 liter) was mixed with 14 parts by weight of water.
In addition to the parts by weight, the acid anhydride group was dissolved by hydrolysis and ring opening.

Add polyvinyl alcohol (Poval 1 manufactured by Kuraray) to this solution.
50 parts by weight of a 6% aqueous solution of 17), precipitated barium sulfate 2
4tL Fh a++ was added and the '4fli solution was stirred and dispersed for 15 hours in a small lume mill. The '4 fli solution was coated on a 100μ thick polyester film, dried and heat treated at 150°C for 2 minutes, and a parent tree with a film thickness of 50μm was coated. formed a layer.

Next, a photosensitive layer was formed thereon in the same manner as in Example 1 to obtain a photosensitive lithographic printing original plate for comparison.

This printed IJλ plate was imagewise exposed and developed in the same manner as in Example 1 to remove the photosensitive layer in the non-image area.

When printing was carried out in the same manner as in Example 1 using the lithographic printing plate that had been @printed in this manner, the background began to become dirty and defects began to appear in the image after about the 100th sheet. When the plate after printing about 200 sheets was observed, the parent wood layer was partially peeled off and the polyester film of the support was exposed.

Comparative Example 2 [Hydrophilizable layer coating liquid] Methyl vinyl ether-maleic anhydride copolymer (manufactured by Aldrich Chemical Company) 0.71 parts polyvinyl acetate (manufactured by Nippon Gosei Kogyo) 0.3 parts by weight Tetrahydrofuran 19 parts by weight The coating liquid for the hydrophilic layer having the above composition was applied onto a polyester film having a thickness of 100 μm and dried at 100° C. for 5 minutes to form a hydrophilic layer having a thickness of 4 μm.

Next, a photosensitive layer was formed thereon in the same manner as in Example 1 to obtain a photosensitive lithographic original plate for comparison.

This printing original plate was imagewise exposed and developed in the same manner as in Example 1, and the photosensitive layer in the non-image area was removed.

When printing was carried out in the same manner as in Example 1 using the lithographic printing plate prepared in this manner, the background began to become dirty from about the 300th plate. Further, when the plate surface after printing about 500 sheets was observed, the hydrophilic layer was partially peeled off, and the polyester film of the support was exposed.

Comparative Example 3 0.5 parts by weight of oxidized powder and 1 part of tetrahydrofuran.
2 parts of 5i ff were stirred and dispersed in a ball mill for 5 hours, and 0.5 parts of methyl vinyl ether-maleic anhydride copolymer was added.
A solution of 5 parts dissolved in 4.5 parts m of tetrahydrofuran was added, and further stirred and dispersed with IW for 30 minutes to prepare a coating solution for a hydrophilic layer.
Coated on a μm polyester film and heated to 100°C for 5 minutes.
It was dried for a minute to form a hydrophilic layer having a thickness of about 4 μm.

Next, a photosensitive layer was formed on this in the same manner as in Example '1,
One photosensitive lithographic printing original plate was obtained for comparison.

This printing original plate was imagewise exposed and developed in the same manner as in Example 1, and the photosensitive layer in the non-image area was removed.

When printing was carried out in the same manner as in Example 1 using the lithographic printing plate prepared in this manner, the background I'11 began to become stained and the image began to be missing from about the 100th sheet. When the plate surface was observed after printing about 200 sheets, it was found that the hydrophilic layer had partially peeled off, and the polyester film of the support was exposed.

Effect As is clear from the results of the above examples and comparative examples,
The printing plate provided with the hydrophilic layer made of the crosslinking reaction product of the maleic anhydride copolymer and the polyisocyanate compound of the present invention has a much higher printing durability than the conventional printing original plate using the maleic anhydride copolymer. Show your gender.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view showing the basic structure of the photosensitive lithographic printing original plate of the present invention. 1...Support, 2...Hydrophilicizable layer, 3...Photosensitive layer, Patent applicant: Ricoh Co., Ltd. - Agent: Patent attorney Hide Komatsu Agent: Kosai Asahi, patent attorney

Claims (1)

[Claims] A hydrophilizable layer comprising a reaction product of a copolymer of maleic anhydride and an isocyanate compound as a main component is provided on the support, and a photosensitive layer is further provided on this layer. Jru photosensitive lithographic printing original plate.