JPS6166697A - Direct-descriptive type offset printing plate - Google Patents

Abstract

PURPOSE:To obtain title original plate for impact-type printer plate which produces no blank during printing using a plate made using a dot printer and also no fouled print from an early stage of printing by applying a coating liquid for image receptor layer on a water-proof support and adjusting the coat to specific density. CONSTITUTION:(B) (i) Inorganic pigment, (ii) water-soluble binder (preferably modified or acetone-acetylated PVA) and (iii) a coating liquid for image receptor layer containing water-proofing agent are applied on (A) water-proof support (e.g.: high-quality paper moisturized and hardened). Then the support thus coated is adjusted to more than 1.02g/cm<2> of density by, for instance, calender processing. As a result, an original plate intended for is made available. It is recommended that a mixture of kaolin and synthetic silica be used as (i) components and aldehyde, etc. as (iii) components.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a direct-printing type offset printing plate, and particularly to a direct-printing type offset printing plate made by a typewriter or a wire tod printer. .

Offset printing plates currently used in the light printing field include (1) direct printing type plates with an image-receiving layer on a water-resistant support, and (2) a photoconductive layer on a water-resistant support. (3) A silver salt photographic type in which a silver halide emulsion layer is provided on a water-resistant support. Among these, the above printing plate (1) can be handwritten with lipophilic ink on the image-receiving layer, printed with a printer, or plate-made directly with a PPC copying machine, so other (2) above, There are some advantages compared to the original printing plate (3).

With the spread of office automation equipment, particularly word processors, it has become more common to use them to perform direct printing on offset printing plates. When making a plate using this word processor, an impact printing printer such as a typeface or wire tod is often used, and the plate is made by printing directly onto a direct-printing type offset printing plate via an ink-impregnated cloth ink ribbon. The transferred ink is fixed on the printing plate and exhibits lipophilic properties.The fixation of the transferred ink and the image receiving calendar is important in obtaining clear printed matter.

CB) Prior art The conventional direct printing type offset printing original plate
581, JP 484802, JP 57-2051
98 etc., and generally, an image-receiving layer coating liquid consisting of an inorganic pigment, a water-soluble binder, a water-resistant agent, etc. is applied onto a water-resistant support to create a hydrophilic and water-resistant image-receiving layer. was used. When printing on this printing plate using an impact method such as a typewriter or wire tod printer, strong localized pressure is applied to the printing area, which tends to dent the image-receiving layer surface.When printing with an offset printing machine, the dented area of the printing area This phenomenon occurs when printing ink does not adhere to the blank area, and only the peripheral area has ink. For this reason, plate making using an impact printer was extremely difficult.

(C) Purpose of the Invention The purpose of the present invention is to provide a direct-printing type offset printing original plate that does not cause white spots during plate making using an impact printer. To provide a direct printing type offset printing original plate that does not show stains.

(0) Structure of the Invention The present inventor has conducted extensive research into improving this phenomenon of white spots, and has succeeded in creating a direct printing type offset printing original plate that does not produce white spots. After carefully investigating the phenomenon in which the printed portion on the surface of the image-receiving layer becomes depressed due to the printing pressure of the printer, it was found that this tendency is greater when the density of the master is lower. That is,
If the density is lower than 1.02 g/cm'', the printed area tends to sink deeply, and for this reason, the master after printing becomes like an intaglio plate, and water accumulates in the recessed area even though it is lipophilic. Ink is applied only to the periphery of the printed area, and no ink is applied to the center of the printed area, resulting in a so-called white spot.However, when the density is 1.02 g/cm2 or more, there is less depression in the printed area and the entire printed area is covered. Because the ink adheres to it, the prints are finished beautifully.

That is, the present invention is characterized in that an image-receiving layer coating solution comprising an inorganic pigment and a water-soluble binder O water-resistant agent is applied onto a water-resistant support, and the density thereof is adjusted to 1.02 g/cm2 or more.

The density of direct printing type offset printing original plate is 1.02g/crr
To achieve a density of r or more, (1) apply an image-receiving layer to the water-resistant support after making the water-resistant support have a density of t, 02 g/am'' or more by calendering or the like; (2) coat the image-receiving layer on the water-resistant support. The coated material is calendered to a cloth density of 1.
．． 02g/cm' or more.

As the inorganic pigment for the image-receiving layer, kaolin alone or a mixture of kaolin and other inorganic pigments can be used, but a mixture of kaolin and synthetic silica is particularly preferred. Kaolin is generally used for paper coating. Things can be used. The chemical composition of kaolin is aluminum silicate, and it has the shape of fine hexagonal plates.

Synthetic silica used in combination includes so-called white carbon, such as metathesis precipitation products caused by thermal decomposition of silicon tetrachloride, acids of sodium silicate, carbon dioxide, ammonium salts, etc., metathesis of sodium silicate, etc. Silica sol obtained through an exchange resin layer or colloidal silica obtained by heating and aging this silica sol, three-dimensional silica in which primary particles ranging from several m4 to several tens of mg are bonded with siloxane by gelling the silica sol and changing the production conditions. This evening silicon compounds mainly composed of silicic acid, such as silica gel which has become secondary particles, and also so-called synthetic molecular sieves produced by heating silica sol, sodium silicate, sodium flumate, etc. as starting materials at 80 to 120°C. Several liters of amorphous synthetic silica are preferred for the present invention.

The amount of synthetic silica added is 5/9 in terms of silica/kaolin ratio.
A ratio of 5 to 60/40 is preferable; as the amount of silica increases, the plate surface becomes more hydrophilic, which is advantageous in preventing printing stains, but on the other hand, the ink transferred from the ink ribbon tends to peel off, reducing printing durability. .

Examples of water-soluble binders include starch or starch derivatives, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, polyvinyl alcohol, casein, vinegar-vinyl-crotonic acid copolymers, ammonium polyacrylates, and especially vinyl methacrylate-anhydride. Completely saponified product of maleic acid copolymer, completely saponified product of vinyl acetate-versatic acid copolymer, completely saponified product of vinyl acetate-acrylamide copolymer, vinyl acetate and ethylenically unsaturated monomer containing silicon in the molecule. Modified polyvinyl alcohol such as a completely saponified product of a copolymer with a polyvinyl alcohol, and a 7-cetoacetylated product (acetoacetylated polyvinyl alcohol) of a completely saponified polyvinyl alcohol are preferred.

Further, water-proofing agents such as aldehydes, amines, melamine-formalin resin, urea-formalin resin, hydrazides, persulfates, or antifoaming agents may be added to the image-receiving layer.

As mentioned above, the original plate of the present invention has a form in which an image-receiving layer is provided on a water-resistant support, and the water-resistant support used here includes melamine-formalin resin,
High-quality paper, resin-coated paper, moisture-strengthened using urea-formalin resin, polyamide epiglolhydrin resin, etc.
Examples include plastic films.

To make the direct printing type offset printing original plate according to the present invention,
An image-receiving layer coating solution containing inorganic pigments such as kaolin and silica, a water-soluble binder, and a water-resistant agent is coated on a water-resistant support with a density of 1.02 g/c or more by calendering. and dry at 80-150℃,
It is sufficient to form an image-receiving layer with a thickness of about 20 IL, or to reduce the density to 1.5L by calendering after coating the image-receiving layer.
It may be 02g/Crr11 or more.

In this case, a water-resistant intermediate layer may be provided between the support and the image-receiving layer to further improve rigidity, and a backing layer may be provided to prevent curling on the back side of the support. may be provided.

The intermediate layer (1 to 20 ml thick) is acrylic resin, SBR.
, MBR, NBR1, emulsion type resins such as vinyl acetate-ethylene copolymers, or solvent-soluble resins such as epoxy resins, polyvinyl butyral, polyvinyl acetate, polyvinyl chloride, etc. are used alone or in combination of two or more parts. Also, a suitable amount of pigment may be added to this intermediate layer.

Backcoat M (1 to 20 ml thick) is starch or starch derivative, carboxymethylcellulose.

Cellulose derivatives such as hydroxyethyl cellulose, polyvinyl alcohol, casein, vinyl acetate-crotonic acid copolymer, water-soluble resins such as ammonium polyacrylate, bad acrylic resins, emulsion type resins such as SBR, MBR1 vinyl acetate-ethylene copolymer These may be used alone or in combination of two or more. A suitable amount of pigment may also be added to this backcoat layer.

(E) Examples The present invention will be explained in more detail by way of examples.

Example 1 An intermediate layer coating solution having the following composition was coated on the surface of a support (100 g/rn' wet reinforced paper) and dried at about 130°C to form an intermediate layer of about 15 g/rn'.

[Intermediate layer coating liquid]

Carboxyl-modified SBR latex (solid content 50%) 120 parts 10% aqueous solution of oxidized starch 100 parts Zikrite 5
200 parts of 0% aqueous dispersion (sericite content 35%)
Inorganic pigment, manufactured by Zikrite Chemical) 80% aqueous solution of melamine resin 12 parts (trade name: Violet Resin-613゜ manufactured by Sumitomo Chemical Tai) 35% aqueous solution of curing catalyst 1.2 parts (trade name: Accelerator ACX-P, (Manufactured by Jumin Kagaku N) Next, a back coat layer coating liquid having the following composition was applied to the back side of this support, and dried at about 130°C to give about 15 g.
A back coat layer of /rn' was provided and calendered to obtain a water-resistant support having a density of 1.10 g/cm'.

C back coat layer coating solution] SBR latex 10 parts (solid content 50%) 50 parts of a 10% aqueous solution of polyvinyl alcohol (trade name Tararebovar 117, manufactured by Kuraray) 50% aqueous dispersion of kaolin 100 parts Melamine resin 8
0% aqueous solution 2 parts 10% ammonium chloride
Aqueous solution 2 parts water
Further, 50 parts of this was coated with an image-receiving layer coating solution having the following layer composition, and dried at about 130°C to give about 8 g.
An image-receiving layer of /m' was formed. The density of the direct printing type offset printing original plate obtained at this time was 1.08 g/crn'.

[Image-receiving layer coating liquid]

100 parts of a 50% dispersion of kaolin (trade name: Ultra White-90°, manufactured by Engelhard) 250 parts of a 20% dispersion of synthetic silica (trade name: Thyroid 308, manufactured by Fuji Davison Chemical) 200 parts of a 10% aqueous solution of polyvinyl alcohol (Product name: Tararebovar 117. Manufactured by Kuraray ■) 80% aqueous solution of melamine resin 2.5 parts (Product name: Sumirezu Resin-813, manufactured by Sumitomo Chemical ■) 10% aqueous solution of ammonium chloride 2 parts water
60 copies When this direct printing type offset printing original plate was made into a printing plate using a Mitsubishi Japanese word processor Office Ace 200 dot printer (manufactured by Mitsubishi Kemari), there were few dents in the printed area, and this was used for offset printing. When printing was carried out using a machine (Gestera Toner 338, manufactured by Gestella Toner Co., Ltd.), there was no staining from the beginning, and a clear printed matter with no white spots was obtained that was better than an SOO sheet.

Comparative Example 1 The water-resistant support of Example 1 had a density of 0 and 99 g/c.
A press-type offset printing original plate was obtained in the same manner as in Example 1 except that a blank plate was used. The density of the obtained original plate was 0.97 g/c. When this original plate was plate-made using the dot printer of Example 1, quite deep depressions were observed in the printed area. Furthermore, when printed on an offset printing machine, only printed matter was obtained that had some imperfections.

Example 2 The image-receiving layer coating solution was applied to the water-resistant support of Example 1 without calendering, and then calendering was performed to give a density of 1.07 g/crn' to obtain a direct printing offset printing original plate. . When this master plate was made using a dot printer, there were few dents in the printed area, and when it was printed using an offset printing machine, it was free from stains from the beginning and a clear printed matter with no white spots was obtained that was better than an SOO sheet.

Example 3 The same amount of modified polyvinyl alcohol (trade name Gosenal?-330H, completely saponified vinyl acetate-maleic anhydride copolymer 1 manufactured by Nippon Gosei Kagaku) was added to the same amount of polyvinyl alcohol in the image-receiving layer coating solution of Example 1. A direct printing type offset printing original plate with a density of 1.06 g/cm'' was obtained in the same manner as in Example 1, except that the original plate was replaced with . However, there are few dents in the printed area,
When this was printed on an offset printing machine, there were no stains from the beginning, and more than 500 clear prints with no holes were obtained.

(F) Effects of the Invention As is clear from the Examples, 1. The direct-printing type offset printing original plate of the present invention does not produce white spots during printing even when plate-formed by a dot printer, and no stains are seen from the initial stage of printing. It has great value as a direct printing type offset printing plate for plate making using impact printers.

Claims (1)

[Claims] 1. An image-receiving layer coating solution containing an inorganic pigment, a water-soluble binder, and a water-resistant agent is coated on a water-resistant support, and its density is reduced to 1.
．． A direct printing type offset printing original plate characterized in that it is prepared to have a density of 0.02 g/cm^2 or more. 2. Direct printing type offset printing original plate according to claim 1, wherein the water-soluble binder is modified polyvinyl alcohol or acetoacetylated polyvinyl alcohol.