JPH10133390A - Automatic developing machine for photosensitive planographic printing plate and developing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the vignetting of an image part and to make the omission property of a non-image part by providing a machine with plural non-driving rollers rotated by the contact of a photosensitive planographic printing plate and plural driving rollers having a developing promotion member rubbing the upper surface of the photosensitive planographic printing plate. SOLUTION: The carrying lowermost point of the photosensitive planographic printing plate in a dipping type developing tank is not provided with the driving roller but it is provided with the non-driving roller 4 rotated by the contact (friction) with the photosensitive planographic printing plate. Then, two or more driving rollers 6-8 having the developing promotion member are arranged at and after the lowermoset point of the printing plate. Then, the photosensitive planographic printing plate is moved on a carrying guide plate 8 in the case that it is the one-side plate. Besides, the upper surface of the printing plate is brought into contact with the roller 4 at the carrying lowermost point and the roller 4 is rotated by frictional force. Thereafter, the printing plate is passed through the driving rollers 6-8 having the developing promotion member by such contact pressure that it is lightly brought into contact with them without causing the vignetting of the image part or the damage of a film. After the printing plate is passed through the developing promotion member, it comes out from developer and it is interposed by a pair of squeeze rollers 3. Then, the developing processing thereof is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic developing machine and a developing method for developing a large number of imagewise exposed photosensitive lithographic printing plates. More specifically, the present invention relates to an automatic developing machine and a developing method in which image quality is good and stable development can be performed, and the developing tank is an immersion type developing tank.

[0002]

2. Description of the Related Art Conventionally, as a developing method for developing a large number of photosensitive lithographic printing plates subjected to image exposure, for example, JP-A No. 1-3
Japanese Patent No. 10354 proposes a so-called dip development system in which a photosensitive lithographic printing plate is transported in a developing tank filled with a developer, immersed in the developer, and developed. Also, in order to perform good development processing with less residual film on the non-image area and to shorten the time required for development, a development accelerating member is arranged in the developing tank, and the surface of the photosensitive material is rubbed in the developing solution. A developing method has been proposed and put to practical use.

[0003] As the development accelerating member, a brush roller or the like driven separately from conveyance has been mainly used. However, in order to efficiently remove the residual film in the non-image area and reduce the time required for development, if the contact pressure of the brush on the printing plate is increased or the number of rotations of the brush is increased, the image area may be thinned or damaged. Often occurred. In particular, in the case of a photosensitive lithographic printing plate having a low image intensity, these image portions are remarkably damaged, and in order to obtain a complete printing plate of the image portion, the non-image portion is hardly removed and a residual film is formed. Improving the removability of the image area will cause the image area to lose image quality (damage such as film thinning of the image area and peeling from the interface of the support, hereinafter referred to as “image quality”).
), And it becomes impossible to balance the vignetting of the image portion and the removability of the non-image portion. Examples of a photosensitive lithographic printing plate having a low image intensity include many using a high-sensitivity photosensitive material, and particularly include a high-sensitivity photopolymer type photosensitive lithographic printing plate. Therefore, it is often proposed that these plates be subjected to a heat treatment or the like to increase the image intensity before development, but the heat treatment requires a large load on the apparatus, and it is difficult to control the plate to maintain a constant image intensity by heating. There are many problems. In addition, the action by heating acts not only on the image portion but also on the non-image portion, and therefore has an adverse effect such that the removal of the non-image portion is deteriorated.

Further, even in the case of a photosensitive lithographic printing plate having a high image intensity without causing the image portion to be blurred, a brush plate is required to shorten the developing time and efficiently remove the residual film in the non-image portion. Although the contact pressure of the brush is increased or the number of rotations of the brush is increased, high speed rotation or high contact pressure of the brush shortens the life of the brush, which is not preferable. Conventionally, the driving brush was often arranged at the lowermost point of transport of the photosensitive lithographic printing plate in the immersion type developing tank, but at the bending point of the printing plate, the contact pressure between the printing plate and the driving brush was kept constant. In some cases, uneven development occurred.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic developing machine for a photosensitive lithographic printing plate wherein the contact pressure between the development promoting member and the printing plate is constant and the life of the development promoting member is long. That is. Another object of the present invention is to provide an automatic developing machine for a photosensitive lithographic printing plate which has no image portion of the developed lithographic printing plate and which has good removability of a non-image portion. . Another object of the present invention is to provide a method for developing a photosensitive lithographic printing plate which is free from image blurring in the image portion of the photosensitive lithographic printing plate and has good removability in a non-image portion.

[0006]

According to the present invention, there is provided an automatic developing machine for a photosensitive lithographic printing plate, wherein the developing tank for the photosensitive lithographic printing plate is an immersion type developing tank. A non-driving roller which is located at a position at which the photosensitive lithographic printing plate is transported at the lowest point in the developing tank and is in contact with the upper surface of the photosensitive lithographic printing plate, and which is rotated by the contact of the photosensitive lithographic printing plate; An automatic developing machine for a photosensitive lithographic printing plate, comprising at least two drive rollers provided with a development promoting member for rubbing the upper surface of the photosensitive lithographic printing plate behind the lowermost point of the conveyance. And a developing method using the automatic developing machine.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the automatic developing machine of the present invention, the developing tank is of an immersion type. In the automatic developing apparatus of the present invention, the photosensitive lithographic printing plate is transported at the lowest point in the immersion type developing tank without a driving roller, and is rotated by contact (frictional force) with the printing plate. It has a non-driving roller. The non-drive roller has a function of a fulcrum (bending point) when the printing plate is transported in the developing tank. The material of the non-driven roller is not particularly limited as long as it is a roller having a resistance to a developing solution, particularly an alkali, and examples thereof include a polyurethane, a nitrile rubber, and an ethylene-propylene copolymer rubber. The non-driving roller may be provided with a development promoting member, if necessary. In this case, the development promoting member includes, for example, molton, and the material thereof includes, for example, rayon, polypropylene, and vinylon. The diameter of the non-driving roller (including the development promoting member when a development promoting member is provided) is usually about 10 mm to 100 mm.

Since the above-mentioned non-driving roller is rotated by contact (frictional force) with the printing plate, the load is hardly applied to the surface of the printing plate, and the occurrence of uneven development can be suppressed. Further, the automatic developing apparatus of the present invention has two or more drive rollers provided with a development promoting member and rotated by a driving means, behind the lowermost point of transport of the printing plate. The development accelerating member has a function of rubbing the surface of the printing plate immersed in the developing solution with the rotation of the driving roller to promote the development of the printing plate, and is not necessarily directly involved in the transport of the printing plate. It should be understood that no.

As the development accelerating member provided in the driving roller, a molton or a brush is preferably used, of which a molton is more preferable. When the development accelerating member is a moleton, examples of the material include rayon, polypropylene, and vinylon. In the case of a brush, the material of the bristle is, for example, nylon or polypropylene, and a material in which a compound such as carbon black is mixed to improve the strength can be used. The diameter of the driving roller (including the development promoting member) is usually about 10 mm to 100 mm.

The present invention is characterized in that two or more drive rollers provided with a development accelerating member are provided after the lowest point of the printing plate. That is, by providing two or more drive rollers, the load per one development development member can be reduced,
Thus, it is possible to prevent the image portion from being blurred or film-thinning caused by each development promoting member, and to improve the removal of the non-image portion by using a large number of development promoting members.

The number of drive rollers used in the present invention is two.
It is sufficient that the length of the development promoting member is not less than the number of the developing promotion member.
When the load per book is reduced, the non-image portion can be reliably removed by increasing the number of the development promoting members by the reduced load per book. Therefore, this number varies depending on the plate material and the developing conditions.

Next, the rotation of the driving roller will be described.
The ratio n between the driving roller surface speed and the printing plate transport speed is:
The number of rotations of the driving roller is f (rpm), and the diameter of the roller is R
(Cm), the transport speed of the printing plate is v (cm / min), and the pi is π, and n = f · π · R / v. n>
When 0 (f> 0), it means that the drive roller rotates in the same direction as the transport direction of the printing plate, and n <0 (f <0)
In the case of, it means to rotate in the opposite direction. Here, the surface of the drive roller means a surface of the drive roller provided with the development promoting member, which is in contact with the printing plate, that is, the surface of the development promotion member.

When n = 0, it means that the drive roller is not rotating (that is, it is fixed), the printing plate and the drive roller surface have a relative speed, and the development promoting member The surface of the printing plate is rubbed by this, but it is rubbed at a certain place on the development accelerating member, which causes local deterioration of the development accelerating member, which is not preferable. Also, n
If = 1, the relative speed between the drive roller surface and the printing plate is 0
Therefore, the surface of the printing plate is not rubbed by the development accelerating member, and cannot exhibit the development accelerating effect. Therefore, in the present invention, cases where n = 0 or n = 1 are excluded.

The preferred range of n depends on the transport speed of the printing plate, the diameter of the driving roller, and the developing conditions.
It is -1 or less and 2 or more and 60 or less, and more preferably -50 or more and -3 or less and 4 or more and 50 or less. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view as an example of the immersion type developing tank of the present invention. A thick solid line 1 in FIG. 1 indicates the developing tank itself. As the material, a plastic such as polyvinyl chloride having a width of 10 mm is suitably used. The horizontal line 15 in the developing tank in this figure indicates the liquid level of the developing solution.

The photosensitive lithographic printing plate is processed from left to right in the drawing. The processing speed can be arbitrarily controlled according to the plate material, but the range is about 30 cm / min to 200 cm / min. Although a detailed transport mechanism is not shown in FIG. 1, the photosensitive lithographic printing plate is transported by driving and rotating the upper rollers of the transport roller pairs 2 and 3 in combination with a motor and a gear.

The temperature of the developing solution can be arbitrarily controlled in accordance with the printing plate material, but the range is generally about 10 ° C. to 50 ° C., and the temperature is controlled by a heater or the like (not shown) if necessary. The developing tank is usually provided with a developer circulation mechanism (not shown), and the developer is circulated. The photosensitive lithographic printing plate enters the developing solution while being supported by the developing entry roller pair 2. When the photosensitive lithographic printing plate is a single-sided printing plate, the photosensitive lithographic printing plate moves on the transport guide plate 8 (the actual transport route is the route shown by the broken line 14). Then, the lower surface of the printing plate comes into contact with the non-driven roller 4 at the lowermost point of the conveyance, and the non-driven roller rotates by the frictional force.

Thereafter, the printing plate passes through the drive rollers 6, 7, and 8 provided with the development promoting members at a contact pressure of such a degree as to lightly contact them without causing image blurring or film thinning in the image portion. When the photosensitive lithographic printing plate is a double-sided printing plate, there is no guide plate 8, and similar development promoting members 9, 10, and 11 are arranged at positions facing 5, 6, and 7. Between the printing plates.

After passing through the development accelerating member, the plate comes out of the developer and is supported by the developing squeegee roller pair 3 to complete the developing process. In addition to the immersion type developing tank of the present invention, the automatic developing machine that can be used in the present invention includes a pre-development processing tank (such as heating or washing), a washing tank (such as a rinse), a gumming tank, and a drying tank as required. Various functions can be provided.

[0019]

The present invention will be described below more specifically with reference to examples and comparative examples. As a photosensitive lithographic printing plate, a photosensitive lithographic printing plate of high sensitivity photopolymer type (size 10
(30 mm x 800 mm) was prepared as follows.

Highly sensitive photopolymer type photosensitive lithographic plate
Preparation of a printing plate After an aluminum plate having a thickness of 0.24 mm was degreased, the surface was polished with a nylon brush while flowing a liquid in which pumice powder was suspended in water, and grained. This aluminum plate was subjected to an anodic oxidation treatment at 35 ° C. for 1 minute at a current density of 4 A / dm ² using 30% phosphoric acid as an electrolytic bath to obtain an aluminum support having an oxide film having a film weight of 17 mg / dm ^2. Was. A coating solution of the photopolymerizable composition having the following composition was applied to the obtained support using a bar coater so as to have a dry film thickness of 2 g / m ² and dried.

Coating solution of photopolymerizable composition 30 parts by weight of trimethylolpropane triacrylate 20 parts by weight of ethylenic compound (A) having the following structure 50 parts by weight of polymer binder-1 having the following composition Sensitizer (B) having the following structure 2 parts by weight Activator (C) having the following structure 2 parts by weight 2-methylcaptobenzothiazole 5 parts by weight Copper phthalocyanine pigment 3 parts by weight Methyl ethyl ketone 900 parts by weight

(Polymer Binder-1) Methyl methacrylate / isobutyl methacrylate / isobutyl acrylate / methacrylic acid / 2-hydroxyethyl acrylate = 35/35/10/15/5 mol% copolymer, M
_W = 85000

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

On a plate obtained by coating and drying, a protective layer solution having the following composition containing a water-soluble polymer binder was applied using a bar coater to a dry film thickness of 4 g / m ² and dried. Was performed to obtain a photosensitive lithographic printing plate of a high sensitivity photopolymer type comprising a photopolymerizable photosensitive layer and a protective layer.

Protective layer solution containing a water-soluble polymer binder polyvinyl alcohol GL-03 10 parts by weight (manufactured by Nippon Synthetic Chemical Co., Ltd.) Liponox NC-95 (manufactured by Lion Corporation) 0.02 parts by weight 90 parts by weight of salt water

High sensitivity photopolymer type photosensitive lithographic printing plate
Exposure of the printing plate Image exposure is performed by an inner drum type plate setter PI-R of an argon ion laser manufactured by Dainippon Screen Mfg. Co., Ltd.
1080. At this time, the exposure conditions are a plate surface light quantity of 3.5 mW and a resolution of 4000 dpi. The exposed image was exposed as shown in FIG. 2 so that unevenness in development, film loss, blemishes and the like could be evaluated. The screen ruling is 17
Squares were used for the screen dots in five lines, and the screen gradation was performed without correction.

Preparation of Developing Solution and Replenisher A developer having the following composition, diluted three times with water, is used for 24 liters per automatic developing machine.
A 5-fold dilution was prepared per automatic developing machine.

Automatic Developing Machine (1) An automatic developing machine having the same structure as the automatic developing machine HL-860X manufactured by Mitsubishi Chemical Corporation was used. However, in this embodiment, a developing tank having a structure as shown in a cross section in FIG. 3 was used. In FIG. 3, the non-driving roller 4 is EPDM.
(Ethylene-propylene copolymer rubber), and the lowermost point of plate transport is below the non-driven roller 4. Reference numerals 5 and 7 denote drive rollers provided with a rayon-made molton as a development promoting member. The development conditions are shown in the results.

Automatic developing machine (2) In the comparative example, a developing tank having a structure as shown in a schematic sectional view of FIG. 4 was used as a developing tank. Reference numerals 5 and 7 denote drive rollers provided with a rayon-made molton as a development promoting member.
The lowest point of conveyance is the lower part of the drive roller 5.

The current image embodiment, the developing solution was prepared in both Comparative Examples were set development temperature to 30 ° C. Put replenisher. The transport speed of the printing plate was set to 80 cm / min, and the number of rotations of the drive roller (developing member: 4.0 cm in diameter) was set to 100 rpm (n
Corresponds to about 15.7). In each of Examples and Comparative Examples, the protective layer was removed in a washing tank prior to the development entry, washed with water after the development squeegee, and further set in a gumming tank so that water was circulated without gumming and then dried and output. . The high-sensitivity photopolymer type photosensitive lithographic printing plate exposed under the above conditions was developed.

Developer potassium hydroxide 1.5% by weight Potassium silicate A 11% by weight Perex NBL (manufactured by Kao Corporation) 5% by weight (sodium alkylnaphthalene sulfonate; content 35%) Water 82.5% by weight

Replenisher Developing solution and the same composition evaluation method In order to examine the non-image area removability using the 90% halftone dot area 12 shown in FIG. 2, a halftone area system was used at an interval of 50 mm from the head of the image. The point area ratio was measured. It has been found that the halftone dot area ratio is reduced when the removability is good. Also,
The reflection density was measured at intervals of 50 mm from the top of the solid portion in order to check film loss in the image portion using the solid portion 13 shown in FIG. The thickness of the image portion and the reflection density are proportional.

Results The above evaluation results are shown in Table 1 below.

[0036]

[Table 1]

From the above results, in the embodiment, the halftone dot area ratios are all constant at 93%, and appropriate omission of non-image portions is secured over the entire plate. The difference from 90% is due to the optical dot gain. In addition, the reflection density of the image portion also coincides within the error range and is the same as the highest value in the comparative example, which indicates that there is no film loss and no development unevenness occurs.

On the other hand, in the comparative example, most of the dot area ratios were higher than 93%, indicating that the removability was insufficient. In the portion 150 mm from the top, 93% is obtained, and the removability is appropriate. However, the reflection density of this portion is as low as 1.14, and film loss occurs. 750m to 850m
The dot area ratio decreases toward m, and the reflection density also decreases extremely. At 850 mm, it is less than 93% and is in an extremely over developed state. That is, in the comparative example, first, unevenness occurs in the development direction of the plate. Furthermore, it can be seen that film loss occurs in a portion where the removability is sufficiently ensured, and the removability is insufficient where no film reversal occurs. When the over-developing state is extremely caused by the development promoting member as in the comparative example, the life of the development promoting member is short. When the over-development state is always appropriately maintained as in the embodiment, the life of the development accelerating member is longer than the above case.

[0039]

According to the automatic developing machine for photosensitive lithographic printing plates of the present invention, the contact pressure of the development accelerating members is constant and their life is long. Thus, a photosensitive lithographic printing plate having no image blurring in the non-image area and having good removability in the non-image area is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one embodiment of an immersion type automatic developing machine of the present invention.

FIG. 2 is a schematic view of a photosensitive lithographic printing plate used in Examples and Comparative Examples.

FIG. 3 is a schematic sectional view of an automatic developing machine used in Examples.

FIG. 4 is a schematic sectional view of an automatic developing machine used in a comparative example.

[Explanation of symbols]

1 Developing tank 2 Conveying roller (entry roller) vs. 3 Conveying roller (developing squeegee roller) vs. 4 Non-driving roller 5, 6, 7 Driving roller 9, 10, 11 Driving roller (used when the printing plate is a double-sided plate) 12 90% halftone dot portion 13 Solid portion 14 Printing plate transport path 15 Liquid level of developer

Claims (6)

[Claims] In an automatic developing machine for a photosensitive lithographic printing plate, a developing tank for the photosensitive lithographic printing plate is an immersion type developing tank,
At the lowest point of transport of the photosensitive lithographic printing plate in the immersion type developing tank, a non-rotating photosensitive lithographic printing plate is present at a position in contact with the upper surface of the photosensitive lithographic printing plate and is rotated by the contact of the photosensitive lithographic printing plate. A photosensitive lithographic printing plate comprising: a driving roller; and at least two drive rollers provided with a development promoting member that rubs the upper surface of the photosensitive lithographic printing plate behind the lowermost point of the conveyance. Automatic developing machine. 2. The automatic developing machine for a photosensitive lithographic printing plate according to claim 1, wherein the non-driving roller has a development promoting member, and the development promoting member is Molton. 3. The automatic developing machine for a photosensitive lithographic printing plate according to claim 1, wherein the non-drive roller does not have a development promoting member. 4. The automatic developing machine for a photosensitive lithographic printing plate according to claim 1, wherein the development accelerating member provided on the driving roller is a Molton or a brush. 5. A photosensitive lithographic printing plate having at least a photopolymerizable photosensitive layer on a support is developed by an automatic developing machine for photosensitive lithographic printing plates according to claim 1. Lithographic printing plate development method. 6. The driving roller according to claim 5, wherein the ratio of the speed of the surface of the driving roller to the transport speed of the printing plate is -60 or more and -1 or less, or 2 or more and 60 or less.
3. The method for developing a photosensitive lithographic printing plate according to item 1.