JP2986365B2 - Lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate precursor, and more particularly, to a lithographic printing plate precursor having excellent printability, excellent image quality, and excellent workability without causing problems such as plate feeding. And a planographic printing plate precursor.

[0002]

2. Description of the Related Art In recent years, with the development of small-size offset printing machines and automatic printing machines, offset printing has become the mainstream in the field of light printing. As a lithographic printing plate precursor used for such offset printing, an electrophotograph in which a photoconductive fine powder such as zinc oxide is applied on a support together with an electrically insulating binder to form a photoconductive layer as a recording layer. A lithographic printing plate is well known, and such a printing plate is used as an offset printing plate by forming an oleophilic image on the surface of a recording layer by an electrophotographic method. Also, an electrophotographic image created separately can be transferred to an image receiving layer containing an inorganic pigment and a binder on a support, that is, a lithographic printing original plate on which a recording layer is formed, using oil-based ink or type printing. A method for forming an image directly on an image receiving layer by using a direct drawing offset printing plate, and a lithographic printing original plate such as one using a photosensitive resin or a silver halide photosensitive material as a recording layer. The ones used are known.

In the lithographic printing plate precursor as described above, the surface of the support is smoothed by calendering or the like in order to obtain a printed matter of good image quality, that is, to achieve excellent plate-making image characteristics. And generally has a smoothness of 200
The smoothing process is performed for about 500 seconds / 10 cc. However, a sufficiently good image has not been obtained with this level of smoothness. Therefore, since a more excellent plate-making image can be obtained as the degree of smoothing is increased, there is a type in which high smoothing is performed by a powerful calendering process or the like.However, the back side is also highly smoothed at the same time. There was a problem in workability such as poor plate feeding in a printing press.

In order to obtain good plate-making image characteristics,
As disclosed in JP-A-3-280067, it has been proposed to mirror-finish a pre-coat layer for forming a recording layer by a cast coating method. 1
There was a problem that the workability was remarkably reduced due to slippage when the support was rolled up into a roll shape.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has excellent workability with good plate feeding properties while maintaining good plate-making image characteristics in a lithographic printing plate precursor without causing problems such as slippage. It provides a lithographic printing original plate.

[0006]

According to the present invention, in a lithographic printing original plate having a recording layer on one side of a support, the surface of the support adjacent to the recording layer has a smoothness of 600 to 5000.
Sec / 10 cc, and the smoothness of the back surface of the support on the side where the recording layer is not formed is 150 to 600 sec / 10c.
c is a lithographic printing original plate characterized by being c. That is, the present invention, without impairing good plate making image characteristics,
Focusing on the smoothness of the support in order to achieve good workability with moderate friction resistance and no slippage and plate making, the surface of the support adjacent to the recording layer, that is, on the substrate or on the substrate It has been found that the object can be achieved by specifying the smoothness of the surface of the under layer and the back surface of the support on the side where the recording layer is not formed, that is, the back surface of the lithographic printing plate precursor. .

In the present invention, the smoothness of the support adjacent to the recording layer needs to be adjusted to 600 to 5000 sec / 10 cc, preferably 900 to 3000 sec / cc.
10 cc. Here, when the smoothness is less than 600 seconds, a good plate-making image cannot be obtained, and conversely, 5000 seconds /
When the support is subjected to a high level of smoothing processing exceeding 10 cc,
There arises a problem that the workability is impaired due to the occurrence of slippage of the winding, and furthermore, in the electrophotographic lithographic printing original plate, there is a possibility that a sufficient fixability of the plate-formed image of the formed toner cannot be obtained.

The method for obtaining a specific smoothness on the side adjacent to the recording layer as described above is not particularly limited. For example, a substrate such as paper described later or a support having an under layer formed on the substrate This is achieved by performing a calendering process. Here, the calendering conditions are appropriately controlled depending on the composition of the substrate and the underlayer, and the types and combinations of rolls such as metallic rolls, resin rolls, and cotton rolls, the number of calender rolls, the roll nip pressure, Conditions such as the roll surface temperature can be appropriately selected. When a support provided with an under layer is used as the support, the composition of the under layer may include the amount of water (increase in water content), the amount of the pigment used, and the particle size (small particle size, large particle size). Control, etc.) can achieve smoothing.

In the lithographic printing plate precursor of the present invention, the smoothness of the back surface on which the recording layer is not formed needs to be adjusted to 150 to 600 seconds / 10 cc, preferably 200 to 500 seconds / 10 cc. is there. Here, the smoothness is 1
In the case of less than 50 seconds / 10 cc, the surface of the recording layer is damaged by irregularities on the back surface, which causes a problem of so-called stain. On the other hand, if the smoothness exceeds 600 seconds / 10 cc, the friction coefficient of the back surface decreases, causing a problem in transportation by a plate making machine or the like. Will lead to dirtying.

In order to adjust the smoothness of the back surface of the support to a specific range as described above, a support comprising a substrate or a back layer provided on the substrate in the same manner as in the case of the side adjacent to the recording layer described above. By subjecting the back surface to a calendering treatment or appropriately adjusting the composition of the substrate and the back layer. Specifically, by adjusting the smoothness to be lower than the case of the support surface on the side adjacent to the recording layer, the calendering conditions are set to be weaker, and the composition of the back layer is It is also possible to perform adjustments such as using a pigment having a large particle size as described later, increasing the proportion of the pigment, and the like, and appropriately adjusting the type of resin used for the back layer as described later. You can also. Furthermore, when a material having high smoothness such as a film or a laminated paper is used as the support, a pigment having a large particle diameter is contained in the back layer, or the surface of the back layer is coated by a coating method. The smoothness can be adjusted by forming irregularities or performing a roughening treatment such as embossing.

In the present invention, the smoothness of each of the recording layer side and the back side is adjusted via the support as described above. It is difficult to simultaneously control the smoothness of the front and back surfaces specified in the present invention by performing the calendering process after forming the under layer, the (recording layer), and the back layer. Therefore, in order to produce the lithographic printing plate precursor of the present invention, the calendering process is performed a plurality of times, for example, a calendering process is performed once after the under layer is formed, and the calendering process is performed again after the back layer is formed. In addition, it is desirable to control the smoothness by a combination of adjustment of the composition of the under layer and the back layer, for example, the proportion and particle size of the pigment, and adjustment of the calendering conditions, as described below.

In the lithographic printing plate precursor according to the present invention, the support may be, for example, wood pulp paper, synthetic pulp paper, a mixed paper of wood pulp and synthetic pulp, nonwoven fabric, plastic film, cloth, metal sheet, or a composite sheet thereof. Or the like can be used as it is. Further, the substrate may be impregnated with a low-resistance substance, subjected to a conductive treatment by coating, vapor deposition or the like, and may be used as a support. Further, in order to obtain the smoothness specified in the present invention, and water resistance and other properties The substrate may be impregnated with a coating liquid composed of a hydrophobic resin, a water-dispersible or water-soluble resin, a pigment, or the like used for an under layer or a back layer described later.

In the present invention, underprintability suitable for a lithographic printing original plate, for example, recording properties, water resistance, durability, etc., is satisfied, and an undercoat is formed on the substrate to adjust to a desired smoothness as described above. It is preferable to use a support provided with a layer and a back layer. The under layer and the back layer are formed by applying a coating solution containing a resin, a pigment, and the like on a support, drying the coating solution, or laminating the coating solution.
Various resins are appropriately selected and used as the resin used here. Specifically, as the hydrophobic resin, for example, acrylic resin, vinyl chloride resin, styrene resin, styrene-butadiene resin, styrene-acrylic resin, urethane resin, vinylidene chloride resin, vinyl acetate resin And the like, as the hydrophilic resin, for example, polyvinyl alcohol-based resin, cellulose-based derivative, starch and its derivatives, polyacrylamide-based resin,
Styrene maleic anhydride copolymers and the like can be mentioned.

Examples of the pigment include clay, kaolin, talc, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica and the like. These pigments are used to achieve the desired smoothness.
As described above, it is preferable to appropriately select and use the particle size.For example, since a relatively high degree of smoothness is required in the under layer, specifically, by cutting small particles or large particles, 8 μm or less, preferably 0.5 to 5 μm
Pigments having a particle size of the order of magnitude are preferably used. Further, since a lower smoothness is required in the back layer as compared with the under layer, a material having a large grain size, specifically, 0.5 to
A pigment having a particle size of about 10 μm is preferably used. It is preferable that the pigment is used in an amount of 80 to 150 parts by weight in the under layer and 80 to 200 parts by weight in the back layer, based on 100 parts by weight of the resin. In order to obtain excellent water resistance, it is effective for the under layer and the back layer to contain a water-resistant agent such as, for example, a melamine resin or a polyamide epichlorohydrin resin.

The recording layer of the lithographic printing plate precursor according to the present invention is not particularly limited, and any known recording layer according to the method of preparing the printing plate precursor can be used. A layer, a direct print recording layer, a recording layer using a photosensitive resin or a silver salt material, or the like is applied. Specifically, the photoconductive layer which is a recording layer in the above electrophotographic method contains at least a photoconductive agent and a binder, and a sensitizer or the like is used as necessary. Examples thereof include inorganic materials such as zinc oxide, cadmium sulfide, titanium oxide, selenium, and selenium-tellurium alloy; organic pigments such as cyanine-based pigments, quinoline-based pigments, and phthalocyanine-based pigments having photoconductivity; and triphenylamine derivatives. And anthracene, a pyrazoline derivative, perylene, tetracene, carbazole and the like. Among them, a printing original plate using zinc oxide as a photoconductive agent is preferable because a remarkable effect is obtained. In addition, as a binder, acrylic resin, styrene resin,
Vinyl acetate resin, vinyl chloride resin, silicone resin,
Various resins such as butyral resin can be used.

In the lithographic printing original plate of the present invention, the coating amount of each of the above-mentioned layers varies depending on the support and the plate-making system.
In an electrophotographic lithographic printing plate precursor using paper as a substrate, the recording layer is 5 to 40 g / m ^2, preferably 15 to 30 g.
/ M ² , the under layer is 5 to 25 g / m ^2, preferably 8 to
15 g / m ^2, the back layer is 5 to 25 g / m ² preferably about 8~15g / m ^2. In the case of the printing original plate of the direct drawing system, substantially the same coating amount may be used. The measurement of the smoothness in the present invention is performed according to the Beck smoothness of JISP8119.

[0017]

Next, the present invention will be described with reference to examples. In addition, the number of parts representing the combination indicates parts by weight. Example 1 A high quality paper having a basis weight of 120 g / m ² was used as a substrate, and a coating for an under layer having the following composition was applied to one surface of the substrate using a Mayer bar, and an under layer having a dry coating amount of 13 g / m ^{2 was} applied. Was provided. The smoothness of the under layer surface is 94 sec / 10
cc, and the smoothness is set to 2015 by the calendering process.
Adjusted to seconds / 10 cc. <Coating for under layer> 200 parts of clay (50% aqueous dispersion) 30 parts of oxidized starch (20% aqueous solution) 150 parts of SBR latex (solid content 49%, Tg 0 ° C.) 150 parts 10 parts of melamine resin precondensate ( Solid content 80%, Sumiretz Resin SR-613)

Further, a coating material for the back layer having the following composition was applied to the other surface of the substrate by using a Mayer bar, and a dry coating amount of 1
After providing a back layer of ² g / m ² , calendering was performed by setting the calender conditions so that the smoothness of the back layer was about 500 seconds / 10 cc. <Coating for back layer> ・ Kaolin (50% aqueous dispersion) 200 parts ・ Polyvinyl alcohol aqueous solution (10%) 60 parts ・ SBR latex (solid content 49% Tg0 ° C.) 100 parts ・ Melamine resin precondensate 5 parts (solid 80%, Sumiretz Resin SR-613)

Next, a coating for a recording layer having the following composition was applied to the under layer of the support using a Mayer bar to form a recording layer having a dry coating amount of 25 g / m ^2.
The plate was seasoned for 16 hours under the condition of% RH to prepare a lithographic printing plate precursor of the invention. The underlayer smoothness of the lithographic printing plate precursor (measured before forming the recording layer) was 1612.
Sec / 10cc, smoothness of back layer is 350sec / 10cc
Met. <Coating for recording layer>-100 parts of photoconductive zinc oxide (Sasex # 2000 manufactured by Sakai Chemical Co., Ltd.)-20 parts of acrylic resin (LR018 manufactured by Mitsubishi Rayon Co., Ltd.)-20 parts-0.1 part of Rose Bengal-0.2 parts of fluorescein・ Methanol 10 parts ・ Toluene 150 parts

Example 2 In Example 1, no calendering treatment was performed after the formation of the under layer, and the smoothness of the under layer was 8 after the formation of the back layer.
A lithographic printing original plate of the present invention was produced in exactly the same manner as in Example 1 except that the calender treatment was performed while setting the calendering conditions so as to be about 00 seconds / 10 cc. The smoothness of the underlayer in such a lithographic printing plate precursor is 81.
5 seconds / 10cc, smoothness of back layer is 576 seconds / 10c
c. In Example 2, the SBR latex in the paint for the back layer was replaced with TBR having a Tg of 0 ° C.
g 30 ° C. was used. Example 3 Example 3 was the same as Example 1 except that the calendering process was performed after setting the calendering conditions after the back layer was formed so that the smoothness of the back layer was about 300 seconds / 10 cc. The lithographic printing original plate of the present invention was produced in exactly the same manner as in Example 1. In this lithographic printing original plate, the smoothness of the under layer was 1493 sec / 10 cc, and the smoothness of the back layer was 182 sec / 10 cc.

COMPARATIVE EXAMPLE 1 In Example 1, no calendering treatment was performed after the formation of the under layer, and the smoothness of the under layer was 1 after the formation of the back layer.
A lithographic printing plate precursor for comparison was prepared in exactly the same manner as in Example 1 except that the calendering treatment was performed while setting the calendering conditions so as to be about 500 seconds / 10 cc.
The smoothness of the under layer in such a lithographic printing plate precursor is 1
421 sec / 10 cc, smoothness of back layer is 802 sec / 1
It was 0 cc. Comparative Example 2 In Example 1, the calendering treatment after the formation of the under layer was not performed, and the smoothness of the back layer was 50 after the formation of the back layer.
A lithographic printing plate precursor for comparison was prepared in exactly the same manner as in Example 1 except that the calendering treatment was performed while setting the calendering conditions so as to be about 0 sec / 10 cc. The underlayer in the lithographic printing plate precursor has a smoothness of 580.
Sec / 10cc, smoothness of back layer is 396sec / 10cc
Met.

Comparative Example 3 In Example 1, the calendering conditions after the formation of the back layer were the same as those of the calendering process except that the smoothness of the back layer was set to about 200 seconds / 10 cc. In the same manner as in Example 1, a lithographic printing original plate for comparison was prepared. In the lithographic printing plate precursor, the smoothness of the under layer was 1305 seconds / 10 cc, and the smoothness of the back layer was 105 seconds / 10 cc. Comparative Example 4 Instead of the calendering treatment after the formation of the under layer in Example 1, rewet casting was performed using a rewetting liquid composed of a 0.5% aqueous solution of calcium formate to obtain a cast-coated paper, and further, a back layer was formed. A lithographic printing original plate for comparison was prepared in exactly the same manner as in Example 1 except that the subsequent calendering treatment was not performed. In this lithographic printing original plate, the under layer had a smoothness of 10,000 seconds / 10 cc or more, and the back layer had a smoothness of 72 seconds / 10 cc.

The lithographic printing plate precursors of Examples 1 to 3 and Comparative Examples 1 to 4 prepared above were evaluated for image quality, plate feedability, and stains as printability. The evaluation was made by an electrophotographic plate making machine ELP-40 manufactured by Fuji Photo Film Co., Ltd.
Plate making at 4V, printing is Ryobi 3200 PFA automatic printing press, ink is F gloss (ink) manufactured by Dainippon Ink & Chemicals, Inc., etching solution is ELP-E manufactured by Fuji Photo Film Co., Ltd., dampening water is Same etchant ELP-E2
Was diluted with 5 parts of water with respect to 1 part. The image quality is printed using a 2cm x 8cm black solid for the printing pattern, adjusting the printing machine so that the printing density of that portion is 1.0 in Macbeth reflection density, and printing the black solid uniformity of the printed matter. Good was evaluated as 、, faintly faint as も の, and faintly noticeable as ×. Kosle dirt is 2 of the printing original plate
The sheets are stacked with the recording layer facing upward, an aluminum metal piece having a bottom area of 5 cm ² and a weight of 20 g is placed thereon, and the lower printing master is fixed so as not to move, and only the upper printing master is fixed. Slides to forcibly reduce the friction between the recording layer of the lower printing plate and the back layer of the upper printing plate, and then making and printing using the lower printing plate. Then, the occurrence of stains on the printed matter was visually evaluated. A sample with no stain was evaluated as ○, a sample with slight stain was evaluated as Δ, and a sample with significantly stain was evaluated as ×. In addition, the plate feeding property was counted by counting the number of cases in which a transport problem occurred when 100 plates were continuously passed. Regarding the plate making properties of the above plate making machines, the planographic printing plate precursors of Examples and Comparative Examples both had good image characteristics. The measurement of the smoothness was performed using a Beck smoothness meter manufactured by Noya Riki Co., Ltd.

[0024]

[Table 1]

The evaluation results are as shown in Table 1. The lithographic printing plate precursor of the present invention can provide a printed matter having good image quality and has excellent printing characteristics without problems of plate feeding property and blemishes. It was confirmed that. On the other hand, the lithographic printing plate precursor of the comparative example has a problem in any of image quality, plate feeding property, and stain due to the smoothness of the under layer or the back layer being out of the range specified in the present invention. there were.

[0026]

According to the lithographic printing plate precursor of the present invention, a printed matter having good image quality can be obtained, excellent plate feeding property without causing a slip problem, and excellent scumming stains are not generated. Since it has good printability, it has a function and effect that does not cause a problem in workability at the time of production of the printing original plate and at the time of plate making and printing.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takao Nakayama, Fuji Photo Film Co., Ltd., 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture (72) Inventor Masayuki Dan 4000, Kawarijiri, Yoshida-cho, Haibara-gun, Shizuoka Fuji Photo Film Co., Ltd. Examiner Toshihiko Nakazawa (56) References JP-A-4-319962 (JP, A) JP-A-56-44690 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41N 1 / 14 G03G 5/14 101 G03G 5/10 G03G 13/28

Claims (2)

(57) [Claims] In a lithographic printing plate precursor having a recording layer on one side of a support, the surface of the support adjacent to the recording layer has a smoothness of 600 to 5000 sec / 10 cc, and the recording layer is formed. A lithographic printing plate precursor, wherein the smoothness of the back surface of the unsupported side is 150 to 600 seconds / 10 cc. 2. The lithographic printing original plate according to claim 1, wherein the recording layer contains zinc oxide.