JPS63256493A - Direct drawing type planographic plate material - Google Patents

Abstract

PURPOSE:To restrain scumming and enhance plate wear characteristics, by incorporating at least one resin comprising at least one functional group which has at least two hydroxyl groups located sterically close to each other in the state of being simultaneously protected by a protective group, as a main constituent of a binder in an image-receiving layer. CONSTITUTION:A resin comprising at least one functional group having at least two hydroxyl groups located sterically close to each other in the state of being simultaneously protected by a protective group is used as a main constituent of a binder in an image-receiving layer. The resin generates hydroxyl groups when being hydrolyzed or decomposed through hydrogen addition by a desensitizing liquid or dampening water used at the time of printing. Therefore, when an image is drawn on the image-receiving layer of a direct drawing type planographic plate material comprising the resin in a surface layer, by using an oil based ink or the like as a printing area, the oleophilic functional groups having hydroxyl groups being protected ensure favorable adhesion between the image receiving layer and the oil based ink or the like, whereby plate wear characteristics are enhanced. In a non-image area, the oleophilic functional groups are hydrolyzed or decomposed through hydrogen addition by the desensitizing liquid and dampening water to become hydroxyl groups, whereby the non-image area is made to be hydrophilic, as clearly contrasted to the oleophilic property of the printing area. Thus, a printing ink is prevented from being adhered to the non-image area at the tine of printing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lithographic printing original plate, and more particularly to a direct-drawing type lithographic printing original plate suitable for office printing original plates and the like.

(Prior Art) Currently, pointillist planographic printing plates having an image-receiving layer on a support are widely used as printing plates for office use. To perform plate making, that is, image formation on such a printing original plate, generally, oil-based ink is drawn by hand on the image-receiving layer, or
Printing methods such as a typewriter, an inkjet method, or a transfer type heat-sensitive method are employed. In addition, a method has recently begun to be used in which a toner image formed on a photoreceptor is transferred and fixed onto an image-receiving layer through the steps of charging, exposure, and development using a plain paper electrophotographic copying machine (RPC). In any case, the printing original plate after plate making is subjected to surface treatment with a desensitizing liquid (so-called etch liquid) to make the non-image area non-greasy, and then subjected to planographic printing as a printing plate.

In conventional straight groove planographic printing plates, surface layers are provided on both sides of a support such as paper with a back layer and an intermediate layer interposed therebetween. The back layer or intermediate layer is made of a water-soluble resin such as PVA starch, a water-dispersible resin such as a synthetic resin emulsion, and a pigment. The surface layer is formed from a pigment, a water-soluble resin, and a water-resistant agent.

A typical example of such a pointillist planographic printing plate is U.S. Patent No. 2.
No. 532,865, the image receiving layer is PV
It is composed mainly of a water-soluble resin binder as shown in A, an inorganic pigment such as silica and calcium carbonate, and a water resistance agent such as an initial condensate of melamine/formaldehyde resin.

(Problems to be solved by the invention) However, the conventional printing plates obtained in this way are
In order to improve printing durability, increasing hydrophobicity by increasing the amount of water-resistant agent added or using a hydrophobic resin will improve printing durability, but the hydrophilicity will decrease and printing stains will occur. On the other hand, there was a problem in that improving hydrophilicity deteriorated water resistance and decreased rigidity. Particularly in high-temperature operating environments of 30° C. or higher, the surface layer dissolves in the soaking water used in offset printing, resulting in major drawbacks such as decreased rigidity and printing stains.

Furthermore, lithographic printing plates are used to draw oil-based inks as image areas on the image-receiving layer, and if the adhesion between the image-receiving layer and the oil-based ink is not good, even if the non-image areas have sufficient hydrophilicity, Even if such printing stains do not occur, there is a problem in that oil-based ink in the image area is missing during printing, resulting in a decrease in printing durability.

The present invention is intended to improve the problems of the drawing type lithographic printing original plate as described above.

An object of the present invention is to provide an original plate for drawing type lithographic printing which has excellent desensitization properties and does not cause not only uniform background smudges over the entire surface but also dotted smudges as an offset original plate.

The object of the present invention is to improve the adhesion between the oil-based ink in the image area and the image-receiving layer, to maintain sufficient hydrophilicity in the non-image area even when the number of prints increases, and to prevent background smearing. An object of the present invention is to provide a lithographic printing original plate having high stiffness.

(Means for Solving the Problems) The above-mentioned aspects are such that in a drawing-type lithographic printing original plate having an image-receiving layer on a support, as a main component of the binder of the image-receiving layer, At least 2 in close proximity
This is achieved by a drawing-type lithographic printing original plate, which is characterized by containing at least one resin containing at least one functional group having two hydroxyl groups simultaneously protected with one protecting group.

The resin of the present invention is a resin that is hydrolyzed or hydrolyzed to produce hydroxyl groups by a desensitizing liquid and soaking water used during printing.

Therefore, drawing type lithographic printing original plates containing the resin as a main component in the surface layer contain lipophilic functional groups with protected hydroxyl groups when drawing on the image receiving layer with oil-based ink etc. Therefore, the adhesion between the receiving layer and oil-based ink etc. becomes good, and the rigidity resistance is improved.

On the other hand, in the non-image area of the main drawing type lithographic printing original plate, the lipophilic functional groups are hydrolyzed or hydrolyzed by the unfattening liquid and soaking water to become hydroxyl groups, and become hydrophilic. Therefore, it is clearly distinguished from the lipophilicity of the image area, and printing ink does not adhere to the non-image area during printing.

As mentioned above, conventionally, the image area was made hydrophobic by drawing oil-based ink on a hydrophilic resin, whereas in the present invention, a resin containing lipophilic functional groups is surface-treated. Based on a completely different idea of making the non-image area hydrophilic, we obtained an innovative drawing-type lithographic printing original plate that combines the advantages of the hydrophilic and hydrophobic properties of the binder resin. This is what we have come to.

In the present invention, examples of functional groups having at least two hydroxyl groups located sterically close to each other protected simultaneously with one protecting group include the following general formula (I
), (II) and (I[[).

In formula (1), R3 and Rz may be the same or different, and are a hydrogen atom, a hydrocarbon group, or -〇-R'
(R' represents a hydrocarbon group), and Z represents a carbon-carbon bond which may be via a heteroatom (provided that the number of atoms between oxygen atoms is 5 or less).

In formula (n), Z is as defined above.

In formula (II[), R,, R2 and Z are as defined above.

A more detailed explanation of the functional group is as follows.

In formula (I), R,, R, may be the same or different, preferably a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms (e.g., methyl group, ethyl group, propyl group). butyl group, hexyl group, 2-methoxyethyl group, octyl group, etc.), optionally substituted aralkyl group having 7 to 9 carbon atoms (e.g. benzyl group, phenethyl group, methylhensyl group, methoxybenzyl group, chlorobenzyl group) groups), alicyclic groups having 5 to 7 carbon atoms (e.g., cyclopentyl group, cyclohexyl group, etc.) or optionally substituted aryl groups (e.g., phenyl group, chlorophenyl group, methoxyphenyl group, methylphenyl group, cyanophenyl group) group) or -〇-R'(R' has the same meaning as the hydrocarbon group in R, , R).

Z represents a carbon-carbon bond which may be via a heteroatom, and the number of atoms between oxygen atoms is 5 or less.

The resin containing at least one kind of functional group used in the present invention can be obtained by a method in which hydroxyl groups contained in a polymer and located in positions sterically close to each other are protected with a protecting group by a polymer reaction, Or produced by a method of polymerizing a monomer containing at least two hydroxyl groups that has been previously protected with a protecting group, or by a polymerization reaction of the monomer and another monomer that can be copolymerized with it. .

As for the production method of the former polymer reaction, for example, a polymer component R'R# (R ' indicates a substituent such as H or CHs) HOB ゝ. 1 (X' represents a linking group) with a compound such as a carbonyl compound, an orthoester compound, a halogen-substituted formate, a dihalogen-substituted silyl, etc. to form at least two hydroxyl groups of interest. It is possible to form functional groups that are simultaneously protected with one protecting group. Specifically, the Chemical Society of Japan, “New Experimental Chemistry Lecture Volume 14, Synthesis and Reactions of Organic Compounds [■]”, page 2505 (published by Maruzen Co., Ltd.), J, F, Mc, 抛ie, rProt
activegroups in Organic C
Chapters 3 and 4 (Plenum
.

It can be produced by a method described in a known literature cited in a review such as published by Press. In the latter method, a monomer with at least two hydroxyl groups protected in advance is synthesized by a known method cited in the above-mentioned review, and then, if necessary, other monomers that can be copolymerized with the monomer are synthesized. A homopolymer or a multicomponent copolymer can be produced by polymerizing the polymer by a normal polymerization method in the coexistence of polymers.

Other monomers to be copolymerized include, for example, fatty acid vinyl carboxylate or allyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, allyl acetate, allyl propionate, acrylic acid, methacrylic acid, croton, etc. acids, unsaturated carboxylic acids such as itaconic acid, maleic acid, fumaric acid, esters or amides of these unsaturated carboxylic acids, styrene derivatives such as styrene, vinyltoluene, α-methylstyrene, α-olefins, Acrylonitrile, methacuronide'J)V
and vinyl group-substituted heterocyclic compounds such as N-vinylpyrrolidone.

In order to further improve the strength of the surface layer, it is possible to utilize the crosslinking effect described below. , carboxyl group, hydroxyl group, etc.) is preferably copolymerized.

These methods are described, for example, in Nippon Kagaku Hall, “New Experimental Chemistry Course Volume 14, Synthesis and Reactions of Organic Compounds (V) J Volume 25.
35 pages (published by Maruzen Co., Ltd.), Yoshio Iwakura: Keisuke Kurita, “
It is described in detail in the known literature cited in the review, such as "Reactive Polymer", page 170 (published by Kodansha).

The molecular weight of the resin of the present invention is from 103 to 106, preferably from 5X10'' to 105.

In addition, the polymer component containing the functional group in the resin is 30 to 1
00% by weight, preferably 35 to 85% by weight.

More specifically, examples of polymer components containing the functional group include the following. However, the scope of the present invention is not limited to the following.

CH3 H3CCH:l OCT.

U113LAI 0CHi co, QC, HsQ
S) fcnz-c-→- C1,co.

00 fcHz C-sunichi CH 2CO α1 fcH2-CI −→− 113ul　　　　　LIL;　i,.

CH.

CH, -O CH.

(21) +CHz−C1(−→− しI′I!−υ 0jiztlsCHzc
00 CH3 Hz ■ (25)+CH,-C+ CH3 IIz U C6H
5. Conventionally known resins can be used in combination with the resin used in the present invention. Examples include silicone resin, alkyd resin, vinyl acetate resin, polyester resin, styrene-butadiene resin, and acrylic resin.

The resin of the present invention may be dissolved or dispersed in an organic solvent,
Furthermore, an aqueous emulsion can also be used.

Therefore, in addition to the resin of the present invention, a water-soluble resin can optionally be used in combination, such as PVA, modified PVA such as carboxyPVA, starch and its derivatives, CMC, hydroxyethylcellulose, casein, gelatin, polyvinylpyrrolidone, Water-soluble resins such as vinyl acetate-crotonic acid copolymer and styrene-maleic acid copolymer can be used.

When these water-soluble resins are used together, it is preferable to use a water-resistant agent. Examples of the water-resistant agent include initial condensates of aminoblast such as glyoxal, melamine formaldehyde resin, and urea formaldehyde resin, and methylolated polyamide resins. Examples include modified polyamide resins such as polyamide-polyamine-epichlorohydrin adducts, polyamide epichlorohydrin resins, modified polyamide polyimide resins, and the like.

The resin of the present invention and known resins can be mixed in any proportion, but the content of the functional group component of the present invention in the total amount of resin is 40 to 100% by weight, preferably 45% by weight or more. Must be included.

If the content of the functional group component is less than 40% by weight, the resulting lithographic printing original plate will not have sufficient hydrophilicity caused by the desensitization treatment using a desensitizing liquid or soaking water, resulting in stains during printing. occurs.

Inorganic pigments are used as other components of the image-receiving layer of the present invention, such as kaolin clay,
Examples include calcium carbonate, silica, titanium oxide, zinc oxide, barium sulfate, and alumina.

The ratio of binder resin/R material in the image-receiving layer varies depending on the type of material and particle size in the case of pigment, but is generally 1/(0.5 to 5) by weight, preferably 1/(0 ,8~
2.5) is appropriate.

In addition, a crosslinking agent may be added to the image-receiving layer in order to further improve the film strength. As the crosslinking agent, commonly used ammonium chloride, organic peroxide, metal soap, organic silane, polyurethane crosslinking agent, epoxy resin curing agent, etc. can be used. Specifically, they are described in "Crosslinking Agent Handbook" edited by Shinzo Yamashita and Tosuke Kaneko, published by Taiseisha (1981).

Examples of the support used in the present invention include wood-free paper, wet reinforced paper, plastic film such as polyester film, and metal plate such as aluminum plate.

In the present invention, an intermediate layer is provided between the support and the image-receiving layer for the purpose of improving water resistance and interlayer adhesion, and a back coat layer is provided on the support surface opposite to the image-receiving layer for the purpose of preventing curling. Can be done.

Here, the intermediate layer is made of acrylic resin, styrene-butadiene copolymer, methacrylate ester-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-
Emulsion type resin such as vinyl acetate copolymer; solvent type resin such as epoxy resin, polyvinyl butyral, polyvinyl chloride, polyvinyl acetate; composed mainly of at least one type of water-soluble resin as mentioned above. However, inorganic pigments and waterproofing agents can be added as necessary.

The structure of the back coat layer is also almost the same as that of the intermediate layer.

When used as PPC plate-making, in order to further reduce scumming of the printing original plate of the present invention, an image-receiving layer, intermediate layer and/or Alternatively, a dielectric agent can be added to the backcoat layer.

The dielectric agent may be inorganic or organic, and inorganic materials include Na, K, Li, Mg, and Z.
n.

Salts of monovalent or polyvalent metals such as Co, Ni, etc., and organic ones such as polyvinylbenzyltrimethylammonium chloride, acrylic resin-modified quaternary ammonium salts, and polymeric cation conductive agents and polymeric sulfonates. Examples include polymeric anionic conductive agents. The amount of these conductive agents added is 3 to 40% by weight of the amount of binder used in each layer.
, preferably 5 to 20% by weight.

In general, to make the lithographic printing original plate of the present invention, an aqueous solution containing an intermediate layer component, if necessary, is applied to one side of the support, dried to form an intermediate layer, and then an aqueous solution containing an image-receiving layer component is applied to one side of the support. An image-receiving layer is formed by coating and drying, and if necessary, an aqueous liquid containing backcoat layer components is coated on the other side and drying to form a backcoat layer. The amount of each of the image-receiving layer, intermediate layer, and back coat layer is 1 to 30 g.
/rrf, 5-20g/bo, 5-20g/po are suitable.

(Example) Examples of the present invention are shown below, but the scope of the present invention is not limited thereto.

Example I A mixed solution of 30 g of N-butyl methacrylate, 20 g of a monomer corresponding to the copolymerization component shown in Specific Example (15), and 200 g of toluene was heated to a temperature of 70°C under a nitrogen stream, and then azobis Isobutyronitrile (AIBN) 1.
0 g was added and reacted for 8 hours. The weight average molecular weight of the obtained copolymer was 43,000.

Next, 35 g of the above copolymer, [ethyl methacrylate/acrylic acid (951
5) Weight ratio] A dispersion obtained by dispersing a mixture of 5 g of copolymer, 200 g of zinc oxide, and 300 g of toluene in a ball mill for 2 hours was applied with a wire bar so that the dry coating weight was 18 g/rrf, It was dried at 110°C for 1 minute to produce a planographic printing original plate.

This original plate was treated with a desensitizing treatment solution (E manufactured by Fuji Photo Film).
LP-EX) was passed once through an etching prosensor, a droplet of 2 μ2 of distilled water was placed thereon, and the contact angle with the water formed was measured with a goniometer and found to be 13°. Note that the temperature was 105° before the unfattening treatment. This indicates that the non-image area of the image-receiving layer of the original plate of the present invention has changed from lipophilic to hydrophilic. The degree of oxidation needs to be 20°C or less in terms of contact angle with water).

Next, a plate was made using commercially available PPC, and the obtained original plate was subjected to a desensitization treatment under the same conditions as above to obtain a printing original plate.

The density of the image area of the obtained original plate was 1.0 or more, there was no ground blur in the non-image area, and the image quality of the image area was clear.

This is an offset printing machine (Huff Duster 800SX type)
Printed on high-quality paper.

Even after printing more than 5,000 sheets, no problems occurred in the background stains in the non-image areas and the image quality in the image areas of the printed matter.

Furthermore, using the above original plate, the environmental conditions were adjusted to 30°C, 180% P.
When a plate was made using commercially available PPC as H, the image of the obtained original plate had a density of 1.0 or more in the image area, no ground blur in the non-image area, and the image quality of the image area was clear. When this was printed in the same manner as above, there was no problem even after printing 2000 sheets.

As mentioned above, the image quality of this original plate did not deteriorate during PPC plate making even under high temperature and high humidity conditions.

Examples 2 to 9 Copolymers shown in Table 1 below were produced under the same polymerization conditions as in Example 1.

Example 1 except that each resin was used in place of the resin in Example 1.
A lithographic printing original plate was prepared in the same manner as above.

In the same manner as in Example 1, the contact angle with water, image quality after PPC platemaking, and printing results are shown in Table 1.

Example IO Resin (J) with the following compound composition (weight average molecular weight 4600
0) 20% emulsion aqueous solution 400g, polyvinyl alcohol 10% aqueous solution [PVA-117 manufactured by Kuraray ■]
A mixture of 200 g and 400 g of a 20% mixed dispersion (zinc oxide/silica (2/8) weight ratio) was dispersed in a ball mill for 1 hour. On top, use a wire bar to achieve a dry adhesion of 8g/
ctll and dried at 130°C for 2 minutes to prepare a lithographic printing original plate.

When processed and printed in the same manner as in Example 1, the image area of the printed matter was clear, and the printed matter had no blur in the non-image area.
I got more than one.

(Effects of the Invention) According to the present invention, it is possible to obtain an original plate for drawing-type lithographic printing in which the occurrence of scumming is well suppressed and also has good stiffness resistance.

Agent: Patent Attorney (8107) Kiyotaka Sasaki,・-
19＞, τ子゛(and 3 others)−・,μs′

Claims (1)

[Claims] In a direct-drawing lithographic printing original plate having an image-receiving layer on a support, at least two hydroxyl groups located in positions sterically close to each other are treated with one protective group as a main component of the binder of the image-receiving layer. A direct drawing type lithographic printing original plate comprising at least one resin containing at least one functional group in a protected form.