JPS6161165A - Processing method of photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To prepare a planographic printing plate having high accuracy with good reproducibility by feeding back a difference between a value of a pre- positioned sensor and a value of a post-positioned sensor, to a replenishing device of a development replenishing liquid. CONSTITUTION:An automatic developing device is provided with a sensor 1 and 2 for detecting a degree of elusion of a photosensitive layer of each photosensitive planographic printing plate in a position on the way of a developing zone, and in its position, so that a difference between a value of a pre-positioned sensor 1 and a value of a post-positioned sensor 2 is calculated and fed back to a replenishing device of a development replenishing liquid. That is to say, when a value of a difference in measured values by both the sensors 1, 2 has become below a prescribed value (5OMEGA), the development replenishing liquid is replenished by operating a pump 6. In case when many pieces of photosensitive planographic printing plates whose supporting body or photosensitive layer is different and developed by the same automatic developing device, a printing plate of high quality can be obtained with high accuracy and with good reproducibility.

Description

Detailed Description of the Invention (1) Object of the Invention (Field of Industrial Application) The present invention relates to a method for replenishing a developer replenisher when developing a large number of photosensitive lithographic printing plates using an automatic developing device. It is.

(Prior Art) Conventionally, a technique is known in which deterioration of a developer caused by developing a large number of photosensitive planographic printing plates is recovered by replenishing the developer with a replenisher.

For example, as described in Japanese Patent Application Laid-Open No. 56-115039, there is a technology that enables long-term running development by replenishing carbon dioxide gas fatigue over time and replenishing processing fatigue through photosensitive printing plate processing. .

Furthermore, the technology described in Japanese Patent Application Laid-Open No. 58-95349 improves the replenishment deviation caused by the size of the image area, which is a drawback of this technology. Examples include a technique in which a replenisher is provided, and when the degree of elution detected by the sensor falls to a predetermined level, a certain amount of replenisher is injected to restore the activity of the developer to its original state.

However, in plate feedback replenishment, which is equipped with a sensor that detects the degree of mosquito elution, accurate replenishment is performed only when developing a large number of the same photosensitive lithographic printing plates, and high-quality printing plates can be obtained. When processing printing plates of different types, manufacturers, etc., the actual situation is that the correlation between replenishment amount and fatigue weakens, and stable processing is no longer possible due to variations in data due to differences in support.

(Object of the Invention) In order to improve these drawbacks, the inventors of the present invention have conducted intensive research and found that the photosensitivity of the intermediate position of the developing zone of an automatic developing device and the position after this position has been improved. A sensor is installed to detect the degree of elution of the photosensitive layer of the lithographic printing plate, and the difference between the value of the sensor placed in front and the value of the sensor placed later is fed back to the developer replenisher replenishment device, allowing for more accurate automatic processing. This enables running development using a developing device.

That is, the object of the present invention is to process photosensitive lithographic printing plates with different amounts of anodic oxidation coatings on aluminum plate supports, with or without such coatings, and with different support materials and thicknesses in the same automatic process. To provide a method for replenishing a developer replenisher by which high-quality printing plates with good reproducibility can be obtained when a large number of printing plates are subjected to running development in a developing device.

Another object of the present invention is to provide a developer replenisher that can produce high-quality printing plates with good reproducibility when a large number of photosensitive lithographic printing plates of different types or manufacturers are processed using the same automatic processor. The objective is to provide a replenishment method.

Yet another object of the present invention is a method for replenishing developer replenisher to produce higher quality printing plates with greater reproducibility.

Still another object of the present invention is to provide a method for replenishing a developer replenisher that enables long-term running development.
be.

(2) Structure of the Invention The purpose of the present invention is to prevent non-image areas on a photosensitive lithographic printing plate in a developing process in which a large number of photosensitive printing plates are developed using an automatic developing device to which a developer replenisher replenisher is connected. Sensors for measuring the degree of elution of the photosensitive layer are provided at at least two positions, ie, a position in the middle of the development zone (~) and a position (B) after the position (A), and the sensor at the position (A) When the difference between the measured value of the sensor at position (B) and the measured value of the sensor at the position (B) is outside the preset value range, the replenishing device is automatically activated and the replenisher is added to the developer. This is achieved by a method for replenishing a developer replenisher in an automatic developing device, characterized in that the developer replenisher is added to the developer replenisher.

Examples of the sensor used in the present invention include a method of measuring the remaining amount of a photosensitive layer on an aluminum plate using an electrical resistance value, as described in JP-A No. 58-95349;
Examples include a method of measuring the capacitance of a film, and a method of detecting light using a densitometer or UV reflection absorbance meter.

The position for installing the sensor is the above position (A).
is the position at the initial stage of development where the influence of the fatigue level of the developer is most pronounced (for example, the position approximately 2 to 7 seconds after the start of development in the case of a generally known positive-type Pa plate), and the position mentioned above (B
) is preferably the position where development is almost completely completed (in the same case, approximately 10 seconds after the start of development) or the position where the development zone is completed.

41 A feature of the present invention is that the amount of anodization of the support, for example aluminum, can be determined by providing sensors at two or more locations and inputting the sensor measurement values of the plate that has almost completed development, that is, the support. It is possible to cancel factors, etc., and truly measures only the fatigue level of the developer, and feeds it back to the replenishment amount.

The sensor may be any sensor that can measure the degree of elution of the photosensitive layer; for example, a pair of electrodes made of metal such as stainless steel is set, and the total resistance value of the remaining photosensitive layer film and the aluminum plate is measured by alternating current. JP-A-58-953, which measures static capacitance by setting a long and thin metal plate on the remaining film on an aluminum plate, and measures the reflection spectrum of ultraviolet light (for example, 280 m).
Examples include a sensor as described in No. 49.

Sensor at position (3) (hereinafter referred to as sensor (g))
The measured value (A) and the position (I3) of the sensor (hereinafter,
The means for determining the difference (b) from the measured value (B) by the sensor (B) may be any method, such as calculation by a microcomputer or general logic circuit.

A preset range of values to be compared with this difference value (B) is determined as follows. In other words, the indicated value when the developer is new and the value when the developer is tired to some extent (
For example, when the number of clear steps on a Kodak Step Tablet changes by approximately H steps, the specified value may be input in advance.

A microcomputer may be used to compare the difference (B) between the measured value (A) and the measured value (B) with the above range.
As a result of this comparison, when the result is out of range, the replenisher pump is activated.

For example, cases such as reflected absorbance, electrical resistance, and capacitance exceed the upper limit of the range and fall outside the range.

The automatic developing device used in the present invention is preferably one that conveys the photosensitive printing plate and has a developing zone, and if necessary, a washing zone, a desensitizing liquid application zone, and a drying zone. However, it can also be used by simply setting it in a conventionally known automatic processor. The sensor can be installed in the same way in the case of an automatic developing device that has two developing tanks. In this case, the sensor at position (B) can be installed in the second developing tank or in the second developing tank. It is preferable to use the area after the developing tank to prevent staining of the cell.

As the developing replenisher replenishing device used in the present invention, a conventionally known replenishing device is applicable, and for example, a replenishing device operated by a pump incorporating a timer is preferably used.

Similarly, due to the feedback replenishment characteristic of the photosensitive printing plate of the present invention, the first photosensitive lithographic printing plate that is developed after being left for a long time may not be refilled in time, resulting in poor development. be. Therefore, it is preferable to incorporate a device (for example, a timer) for replenishing the amount of air fatigue due to time, in addition to the device according to the method of the present invention.

As the developer used in the present invention, for example, when processing a positive photosensitive planographic printing plate,
4-62004, Quantum No. 57-54938, and the like, developers mainly containing alkali metasilicate salts are preferably used.

In addition, as a developer replenisher, the purpose is to replenish the consumed alkaline content, and 81027M, alkali metal metasilicate with a small O ratio, potassium hydroxide, sodium hydroxide 1J11, etc. Aqueous solutions are preferably used.

Potassium metasilicate is preferred.

The developer replenisher preferably has a composition that replenishes the consumed alkaline content, and in the case of an aqueous solution of an alkali metal metasilicate, a composition with a low silicic acid content or an aqueous solution of potassium hydroxide and/or sodium hydroxide is preferably used. Also,
The amount of replenishment is preferably added in proportion to the difference value of the sensor obtained. This method is especially effective when a large amount of large-sized photosensitive printing plates are processed at one time because the liquid can be replenished without delay.

On the other hand, when processing a negative planographic printing plate material, for example, a developer containing an alkaline agent, benzyl alcohol and a surfactant as described in JP-A-50-26601g and JP-A-53-44202; The above-mentioned alkaline aqueous solutions substantially free of organic solvents are preferably used.

As the developer replenisher, a replenisher having a similar composition with a high alkaline content is used.

The photosensitive printing plate used in the present invention has a photosensitive layer whose solubility changes with light irradiation on a substrate such as an aluminum plate, zinc plate, iron plate, chrome-plated iron plate, paper plate, or plastic plate.
05 to 5 g/m. As a photosensitive layer,
A photosensitive layer containing an orthonaphthoquinonediazide compound, a diazonium salt compound, an azide compound, a photopolymerizable compound, a photocrosslinking compound, and, if necessary, an alkali-soluble binder is preferably applied. In particular, a photosensitive planographic printing plate most suitable for the replenishment method of the present invention is a photosensitive planographic printing plate in which a photosensitive layer containing an orthonaphthoquinone diazide compound and a novolac resin is coated on an anodized aluminum plate.

The present invention is characterized by feedback replenishment that focuses on the dissolution speed of the plate, and by a replenishment method that cancels out the factors of the support, so there are various advantages. For example, when processing negative and positive photosensitive planographic printing plates with the same developer, replenishment can be done without regard to the difference in support, which is unprecedented! Da
It is possible to produce printing plates with high quality.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these.

Example 1 (An automatic developing device as shown in Figure 1 was manufactured, and Sakura 2
5-fold dilution of 8th edition developer 5DR-1 2OA'1 Sakura P
Using a 4-fold dilution of S plate development replenisher 5DR-1, Sakura positive-type photosensitive planographic printing plate XX8MP-N// (thickness of aluminum plate 0.20cm, anodic oxide film amount 20cm/d)
d), Positive type photosensitive lithographic printing plate manufactured by Fuji Photo Film %
FPS" (aluminum plate thickness 0.24mm, anodic oxide film amount 1IIn9/dgo), standard exposure (idle fin 2g, distance im 90mm) using halftone original film.
First, after performing the '8MPN /I I
50 sheets of "n" equivalent were processed in succession.Next,
50 plates equivalent to 'FpBtt' were developed in succession, and the finishing quality of the plate was examined.

Subsequently, the process was repeated for each of these 50 photosensitive planographic printing plates made by different manufacturers, until a total of 400 plates were processed. For each of the 28 plates, changes in the number of clear petals on the step tablet (Kodak Step Tablet 42) and changes in the dot area ratio on the plate were observed.

Figure 1 is a schematic cross-sectional view of the automatic developing device used in Example 1. In Figure 1, 1 and 2 are sensors installed to measure the impedance between the electrodes only when the leading edge (non-image area) of the photosensitive lithographic printing plate passes, and the voltage between the electrodes is 1. As the power source, alternating current with a frequency of 10 KHz was used. 1a and 2a are sensors 1 and 2 respectively
The electrode is 1mm thick, 1.5cm thick, 5α long, and made of stainless steel. The distance between electrode 1a and electrode 2a is about 70R% when the center distance is □ and the development time is 20 seconds.
For electrode 1a, the center of the electrode is at the position 5 seconds after the start of development, and for electrode 2
a is the position after 18 seconds. 3 is the control unit, sensor 1
It has a circuit that subtracts the measured value of the sensor 2 from the measured value of , and a circuit that outputs a command to operate the pump when the difference between the constant values on both sides becomes less than a certain value (5Ω). 4 is a developer tank, 5 is a developer replenisher tank, 6 is a pump that operates according to a command from the control unit 3 (one replenishment command corresponds to 20 m1), 7 is a pump that is operated by a timer (30 m/hour), 8 is a pump for showering the developer, 9 is a showering nozzle for the developer, 10 is a rubber roller for conveying the photosensitive planographic printing plate, and 11 is the photosensitive planographic printing plate in the middle of development.

Next, the lithographic printing plate was transferred to an offset printing machine Heidel GT.
Approximately 100,000 sheets were printed using "O-52", and the quality of the finish of the printed matter, the opening of part of the shadow, the ink receptivity, etc. were observed. The results are shown in Table 1.

Comparative Example 1 Of the sensors 1 and 2 of the automatic developing device used in Example 1, 2 was removed, and the indicated value of sensor 1 was set to a constant value (21Ω
) The same operation as in Example 1 was carried out using an automatic developing apparatus in which 2°d of developer replenisher was added when the temperature exceeded 2°C, and the same tests were carried out.

The results are shown in Table 2.

Comparative Example 2 An experiment was carried out in the same manner as in Comparative Example 1, except that the photosensitive lithographic printing plate to be developed was only %SMP-N''.

The results are shown in Table 3.

Table 1 Table 2 Table 3 As shown in Table 3, with the conventional method of detecting the degree of deterioration of the developer using one sensor, high quality and highly stable printing can only be achieved when the same PS plate is repeatedly developed nine times. You can see that the version is obtained. That is, as is clear from the results in Tables 1 and 2, the material, thickness,
When two types of PS plates with different amounts of anodic oxide films are processed alternately in the same automatic developing device, the conventional method of detecting them with a single sensor has been found to be insufficient when starting with 'SMP-N' set. In contrast, the halftone dots of the reproduced image tend to become thicker over time, and there is also a tendency for stains to occur in non-image areas (particularly at the edges of erased traces), making it impossible to obtain satisfactory printed matter. It can be seen that with the method using two sensors, clean, high-quality printed matter can be stably obtained from the start up to a total of 400 sheets.

Example 2 A 3S aluminum plate with a thickness of 0.30 m+ was immersed in a 20X sodium phosphate aqueous solution to degrease it.
Electrolytic polishing was carried out in a N-hydrochloric acid bath at a current density of 3 to 10%.

Then, 1
Anodizing was performed for 1 minute (aluminum plate: A) and 10 seconds (aluminum plate: B), followed by neutralization and washing to obtain two types of aluminum supports. A.

The anodic oxide film amount of B is 30■'d m" and 5, respectively.
It was rv/dl.

Next, the following photosensitive liquid was applied onto these supports using a Whaler, dried, and the following photosensitive liquid was added: 1 part by weight of a condensation resin of pyrogallol and acetone.
Naphthoquinone diazide sulfonic acid ester (compound described in U.S. Pat. No. 3,635,709 (Example 1)
)) ・m-Cresol Formalin Novolac 2 parts by weight Resin ・2-Trichloromethyl-5-[β-0,015(2'
-Benzofuryl)vinyl)-1,1jLIk part 3.4-
Oxadiazole Biftlyapure Blue BOH0.05 (manufactured by Hodo Rikiya Chemical) Part by weight/Methyl cellosolve
A 10 parts by weight photosensitive lithographic printing plate was obtained. The coating amount after drying is A.

B each 22.3 mp/d m:, 22. Oq/
Alata on dm.

Next, a photosensitive lithographic printing plate using both supports A and B was exposed in the same manner as in Example 1, and running development was performed under the same conditions. The scale was 1/10, and the running amount was up to 40 m/l (per mother liquor), about twice that of Example 1, and the finishing of the printing plate was examined.

As a result, even in long-run development, which is approximately twice as long as conventional methods,
, B photosensitive lithographic printing plates using respective supports,
A reproducible, high-quality, and highly stable finish was obtained in each case.

(3) Effects of the invention According to the present invention, different supports (for example, differences in material, thickness, amount of anodic oxide film on the aluminum support, etc.),
When a large number of photosensitive lithographic printing plates having different photosensitive layers (for example, positive type and negative type) are developed in the same automatic developing device, high-quality printing plates can be obtained with good reproducibility.

The feature of the present invention is that it is a feedback replenishment method that focuses on the dissolution speed of the g-photolayer, and that it is a replenishment method that cancels out the factors of the support. Therefore, it is possible to create a lithographic printing plate with higher precision than ever before.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an automatic developing device according to an embodiment of the present invention. 1 and 2... Electric resistance sensor, 1a and 2a
... Electrode, 3 ... Control section, 4. River ...
Developer tank, 5... Developer replenisher tank, 6.
... Pump operated by command from control unit 3, 7.
...Pump that operates on a timer, 8...
・・Showering pump, 9・・Showering nozzle (10・・°・・Transport roller, 11・・・
・i Photosensitive planographic printing plate, 12... Brush roller.

Claims (1)

[Claims] In the development process of developing a photosensitive printing plate using an automatic development device connected to a developer replenisher replenisher, a sensor is installed in the development zone to measure the degree of elution of the photosensitive layer in the non-image area of the photosensitive planographic printing plate. position (A) in the middle of , and the position (A
) in at least two positions after position (B);
The replenishing device automatically operates when the difference between the measured value of the sensor at the position (A) and the measured value of the sensor at the position (B) falls outside a preset value range. A method for replenishing a developer replenisher for an automatic developing device, characterized in that the developer is replenished with the replenisher.