JP2002188985A - Instrument and method for measuring specific gravity, and method of manufacturing planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure specific gravity of a treating liquid continuously without controlling a liquid level in a specific gravity measuring vessel. SOLUTION: A high-pressure receiving housing 26 and a low-pressure receiving housing 40 are attached, with 1000 mm of level difference, to the measuring vessel 18 to which an etchant L of a specific gravity measuring object is fed. A differential pressure corresponding to the level difference 1000 mm is detected by a differential pressure transmitter 30, resulting from a difference between liquid pressures applied to the both housings 26, 40. A computing part 46 computes the specific gravity of the liquid based on the differential pressure and the level difference. A reference water is not required as is required in a conventional specific gravity measuring instrument. The specific gravity is thereby measured accurately and continuously since free from water level fluctuation of the reference water and temperature fluctuation of the reference water. Specific gravity measurement is not affected substantially by fluctuation of an etchant flow rate because the flow rate of the etchant L to the measuring vessel 18 is not required to be held constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specific gravity measuring device and a specific gravity measuring method for measuring a specific gravity of a processing liquid, and a method of manufacturing a lithographic printing plate for controlling the concentration of a processing liquid in an aluminum web from the specific gravity measurement result.

[0002]

2. Description of the Related Art A support for a lithographic printing plate, for example, a thin plate of aluminum (hereinafter referred to as "web") is subjected to a surface roughening treatment to form fine irregularities called grain. By this surface roughening treatment, the water retention of the web as a photosensitive lithographic printing plate after the photosensitive liquid is applied, hydrophilicity, printing resistance,
Printability is improved.

At present, one of the methods for roughening a web is as follows.
As shown in FIG. 3, there is a method of chemically etching the grained web W by spraying an etchant L such as an acid or an alkali from a nozzle 10.

However, in the etching process, the composition of the etching solution L changes with time, so that the concentration of the etching solution L needs to be controlled by a specific gravity measuring device 80.

Here, the measurement principle of the specific gravity measuring device 80 will be described. The specific gravity measuring device 80 includes a specific gravity measuring tank 82, and the etching liquid L in the circulation tank 12 is sent to the specific gravity measuring tank 82 by the liquid sending pump 14.

A differential pressure measuring device 84 is attached to the lower side surface of the specific gravity measuring tank 82. An overflow portion of the etching solution is formed at a position 1000 mm from a measuring point of the high pressure diaphragm of the differential pressure measuring device 84. I have. When the etchant overflows from the overflow section into the overflow tank 86, the liquid column from the level of the etchant to the differential pressure measuring device 84 is maintained at 1000 mm.

A reference water tank 88 is provided alongside the overflow tank 86. The reference water is supplied to the reference water tank 88 and the overflow tank 9 is supplied from the overflow section.
By overflowing to 0, the level of the reference water and the level of the etching liquid are set to the level, and the reference water is sent from the reference water tank 88 to the low-pressure diaphragm of the differential pressure measuring device 84 via the pipe 92.

In the differential pressure measuring device 84, oil is sealed between the high pressure side diaphragm and the low pressure side diaphragm, and a center diaphragm is provided at the center.
When the high-pressure side diaphragm is distorted by the liquid pressure of the etching liquid and the low-pressure side diaphragm is distorted by the water pressure of the reference water, the center diaphragm is distorted via oil according to the pressure difference. The amount of distortion of the center diaphragm is electrically extracted as a differential pressure by a straight gauge,
The specific gravity is calculated from the pressure difference between the etching liquid having a height of 00 mm and the reference liquid.

By the way, in order to accurately measure the specific gravity of the etching solution, fluctuations in the liquid level of the etching solution and the reference water surface are suppressed, and fluctuations in the water temperature of the reference water are prevented in order to eliminate the expansion change due to the temperature change of the oil. Must be suppressed.

However, it is not easy to suppress the fluctuation of the water surface and the liquid surface, and it is necessary to keep the flow rate of the etching liquid constant due to the fluctuation of the liquid surface level of the circulation tank 12 and the clogging of the pipe to the specific gravity measuring tank 82. Is difficult. Therefore, the specific gravity of the etchant cannot be measured continuously.

[0011]

SUMMARY OF THE INVENTION According to the present invention, there is no need to control the liquid level in a specific gravity measuring tank, and the specific gravity of the processing liquid is accurately and continuously measured to guarantee the quality of the processing liquid of a lithographic printing plate. That is the task.

[0012]

According to a first aspect of the present invention, there is provided a measuring tank to which a liquid to be measured for specific gravity is fed, a high-pressure receiving unit attached below the measuring tank and receiving a liquid pressure;
A low-pressure receiving section mounted above the measuring tank at a height difference H from the high-pressure receiving section and receiving a hydraulic pressure; and detecting a differential pressure between the pressure at the high-pressure receiving section and the hydraulic pressure at the low-pressure receiving section. It is characterized by comprising a differential pressure measuring means, and an arithmetic means for calculating the specific gravity of the liquid based on the differential pressure and the height difference H.

In the above configuration, the high-pressure receiving portion and the low-pressure receiving portion are attached to the measuring tank to which the liquid to be measured for specific gravity is supplied with a height difference H. The differential pressure corresponding to the height difference H is detected by the differential pressure measuring means from the difference between the hydraulic pressures received by the high pressure receiving portion and the low pressure receiving portion. Next, the calculating means calculates the specific gravity of the liquid based on the differential pressure and the height difference H.

In this configuration, unlike the conventional specific gravity measuring device, reference water is not required. For this reason, there is no room for the fluctuation of the water level of the reference water and the fluctuation of the temperature of the reference water, so that the specific gravity can be continuously and accurately measured.

Further, it is not necessary to keep the flow rate of the liquid to the measuring tank constant, and it is sufficient that the liquid height is as high as the position of the low-pressure receiving portion. Therefore, there is almost no influence on the specific gravity measurement due to the fluctuation of the liquid flow rate.

According to a second aspect of the present invention, the pressure difference between the high pressure receiving portion and the low pressure receiving portion provided with a height difference H in a measuring tank to which the liquid to be measured for specific gravity is fed is determined by the difference between the pressure difference between the high and low pressure receiving portions. It is characterized in that the specific gravity of the liquid is obtained from the height difference H.

According to a third aspect of the present invention, in a chemical etching step as a pre-treatment until a photosensitive layer is formed on a support of a printing plate, a treatment liquid in a circulation tank is sent to a measurement tank to measure the same. The specific gravity of the processing liquid is determined from the pressure difference between the high and low pressure receiving sections provided with a height difference H in the tank and the high and low pressure receiving sections, and the concentration of the processing liquid in the circulation tank is controlled. It is characterized by:

In the above configuration, the replenishment water is added, etc.
Even if the flow rate of the processing solution sent from the circulation tank to the measurement tank fluctuates, it hardly affects the specific gravity measurement. Therefore, the specific gravity of the processing liquid can be accurately controlled.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific gravity measuring apparatus according to the present embodiment will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the specific gravity measuring device 16 has a measuring tank 18. A liquid sending pipe 20 is connected to the bottom surface of the measuring tank 18, and an etching solution is sent from the circulation tank 12 by a liquid sending pump 14.

An opening 22 is formed below the side surface of the measuring tank 18. This opening 22 is connected to a high-pressure diaphragm 24.
The high-pressure receiving housing 26 is attached in such a state that the housing is sealed by the above. The high-pressure diaphragm 24 is distorted by the pressure of the etching solution.

A high pressure receiving housing 26 is connected to a capillary 28 filled with a sealing liquid. The other end of the capillary 28 is connected to a differential pressure transmitter 30. Thereby, the hydraulic pressure corresponding to the distortion of the high-pressure diaphragm 24 is transmitted to the differential pressure transmitter 30 via the seal liquid.

A liquid chamber 32 is formed at the center of the differential pressure transmitter 30. The liquid chamber 32 is divided into two by a center diaphragm 34, and one of the liquid chambers is closed by an intermediate diaphragm 35 which is distorted by the sealing liquid of the capillary 28.

On the other hand, an opening 3 is provided above the side surface of the measuring tank 18.
6 are formed. In a state where the opening 36 is sealed with a low-pressure diaphragm 38, a low-pressure receiving housing 40 is provided.
Is installed. The center of the low-pressure diaphragm 38 of the low-pressure receiving housing 40 and the high-pressure receiving housing 26
The height difference H from the center of the high-pressure diaphragm 24 is 100
0 mm.

The low pressure receiving housing 40 is connected to a capillary 42 filled with a sealing liquid. The other end of the capillary 42 is connected to the other side of the liquid chamber 32 of the differential pressure transmitter 30 separated by the center diaphragm 34 via an intermediate diaphragm 37.

As a result, the center diaphragm 34 is connected to the liquid pressure on the low pressure receiving housing 40 side and the high pressure receiving housing 2.
When it is distorted by receiving a pressure difference from the fluid pressure on the 6 side, the amount of this strain is electrically extracted as a differential pressure as a resistance change of the strain gauge 44. Then, in the arithmetic unit 46, the height difference H is 1
It is compared with the differential pressure of water (specific gravity 1.0) at 000 mm, and is displayed on the display unit 48 as the specific gravity of the etching solution. Further, a conductivity meter 50 is provided in the liquid sending pipe 20, and the concentration of the etching solution is calculated by the calculation unit 46 from the measured conductivity and specific gravity.

The concentration of the etching solution in the circulation tank 12 is continuously controlled based on the measured concentration, while the etching solution that has risen to the ceiling of the measurement tank 18 is returned to the circulation tank 12 through the return pipe 52. Returned to Further, a supply pipe 54 is connected to the circulation tank 12. The end of the supply pipe 54 is branched, and the nozzle 10 is attached to the branch pipe. From this nozzle 10,
The etching solution sent from the circulation tank 12 by the circulation pump 56 is sprayed on the web W and chemically etched.

The web W is conveyed by a pass roll 60 disposed in the etching tank 58, and the etching solution sprayed from the nozzle 10 is collected in the etching tank 58. The collected etching liquid is returned to the circulation tank 12 through the collection pipe 62.

Next, the difference in performance between the specific gravity measuring device 16 according to the present embodiment and the conventional specific gravity measuring device 80 will be described.

The experiment conditions were as follows: 26 ± 1% of caustic soda and an aluminum concentration of 6.5 ± 0.5% as an etching solution, and the specific gravity was 1.409. The temperature of the etching solution is 76 ° C. ± 0.5 ° C., the ambient temperature is 25 ° C., the temperature of the reference water is 18 ° C. to 40 ° C., and the reference water flow fluctuation supplied to the reference water tank is 1 L ± 0.5 L / min. And

[0031]

[Table 1]

As shown in Table 1, the specific gravity measuring apparatus according to the present embodiment has the following characteristics:
The measurement was performed within an error range of 408 to 1.412. on the other hand,
In the conventional specific gravity measurement device, measurement is performed within an error range of 1.405 to 1.413.

As shown by the above results, in the specific gravity measuring apparatus of this embodiment, there is no room to be affected by the change of the reference water temperature and the fluctuation of the reference water flow rate supplied to the reference water tank, and the water is sent to the measurement tank. It turns out that it is hard to be affected by the fluctuation of the flow rate of the etching solution.

Next, Table 2 shows the relationship between the flow rate of the etching solution sent to the measuring tank and the specific gravity measurement time.

[0035]

[Table 2]

As shown in the above table, it can be seen that the specific gravity measurement time can be reduced by increasing the flow rate of the etching solution. However, in the conventional specific gravity measuring device, if the flow rate flowing into the measuring tank is increased, the flow rate cannot be increased due to large fluctuations in the liquid level, but in the specific gravity measuring apparatus of the present embodiment, the flow rate cannot be increased because the liquid level level is small. Can be increased to shorten the measurement time of the specific gravity.

In this embodiment, the example in which the specific gravity measuring device is used in the etching step has been described. However, the grain size range of the pumice particle size range: 15 to 40 μm, the specific gravity measurement range: 1.1 to 1.3, Concentration: 15%, Aluminum concentration 0.7
%, Specific gravity measurement range: 1.1 to 1.3. In addition, the present invention is not limited to the method of manufacturing a lithographic printing plate, and can be applied to a plant or the like that needs to continuously measure the specific gravity of a processing solution.

Next, a method of manufacturing a lithographic printing plate will be schematically described.

The web having been subjected to electrolytic surface roughening was washed with water, immersed in a 10% by weight aqueous solution of sodium hydroxide at 35 ° C., etched so that the amount of aluminum dissolved was 1 g / m ² , and washed with water. . Next, at 50 ° C. 30% by weight
After being immersed in an aqueous sulfuric acid solution and desmutted, it is washed with water.

Further, a porous anodic oxide film forming treatment was performed in a 20% by weight aqueous sulfuric acid solution (containing 0.8% by weight of aluminum) at 35 ° C. using a direct current. That is, electrolysis was performed at a current density of 13 A / dm ² , and the anodic oxide film weight was adjusted to 2.7 g / m ² by adjusting the electrolysis time. To prepare a negative photosensitive lithographic printing plate using a diazo resin and a binder, the support was washed with water, immersed in a 3% by weight aqueous solution of sodium silicate at 70 ° C. for 30 seconds, washed with water and dried.

[0041] The thus-obtained aluminum support, Macbeth RD920 reflection density was measured with a reflection densitometer 0.30, the center line average roughness R _a as defined in JIS B00601 is 0.58μm met Was.

Next, methyl methacrylate /
A 1.0% by weight aqueous solution of ethyl acrylate / 2-acrylamide-2-methylpropane sodium sulfonate copolymer (average molecular weight: about 60,000) (molar ratio: 50/30/20) was dried by a roll coater to obtain an applied amount of 1.0% by weight. 0.05g
/ M ² .

Further, the following photosensitive solution-1 was applied using a bar coater and dried at 110 ° C. for 45 seconds. The dry coating amount was 2.0 g / m ² . Photosensitive solution-1 Diazo resin-1 0.50 g Binder-1 5.00 g Stylite HS-2 (manufactured by Daido Kogyo Co., Ltd.) 0.10 g Victoria Pure Blue BOH 0.15 g Tricresyl phosphate 0.50 g Dipicolinic acid 0 .20 g FC-430 (Surfactant manufactured by 3M) 0.05 g Solvent 1-methoxy-2-propanol 25.00 g Methyl lactate 12.00 g Methanol 30.00 g Methyl ethyl ketone 30.00 g Water 3.00 g

The above diazo resin-1 was obtained as follows. First, 29.4 g of 4-diazodiphenylamine sulfate (99.5% purity) was added at 25 ° C to 9
It was slowly added to 70 ml of 6% sulfuric acid and stirred for 20 minutes. To this, paraformaldehyde (purity 92%) 3.
26 g was added gradually over about 10 minutes, and the mixture was added to 30
The mixture was stirred at 4 ° C. for 4 hours to allow the condensation reaction to proceed. In addition,
The condensation molar ratio of the diazo compound and formaldehyde is 1: 1. The reaction product was poured into 2 liters of ice water with stirring, and treated with a cold concentrated aqueous solution in which 130 g of sodium chloride was dissolved. The precipitate was collected by suction filtration and the partially dried solid was dissolved in 1 liter of water, filtered, cooled with ice and treated with an aqueous solution of 23 g of potassium hexafluorophosphate. Finally, the precipitate is recovered by filtration and air-dried to give the diazo resin-
1 g was obtained.

Binder-1 was 2-hydroxyethyl methacrylate / acrylonitrile / methyl methacrylate / methacrylic acid copolymer (weight ratio 50/20/26 /
4, average molecular weight 75,000, acid content 0.4 meq /
g) is a water-insoluble, alkaline water-soluble film-forming polymer.

Stylite HS-2 (manufactured by Daido Industry Co., Ltd.)
Is a polymer compound having a higher oil sensitivity than the binder,
It was a copolymer of styrene / mono-4-methyl-2-pentyl maleate = 50/50 (molar ratio), and the average molecular weight was about 100,000.

[0047]

Since the present invention has the above-mentioned structure, there is no need to control the liquid level in the specific gravity measuring tank, and the specific gravity of the processing liquid is accurately and continuously measured to assure the quality of the processing liquid of the lithographic printing plate. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an etching process in which a specific gravity measuring device according to an embodiment is used.

FIG. 2 is a cross-sectional view illustrating a main part of the specific gravity measuring device according to the embodiment.

FIG. 3 is a block diagram showing an etching process using a conventional specific gravity measuring device.

[Explanation of symbols]

 18 Measurement tank 26 High pressure receiving housing (high pressure receiving part) 30 Differential pressure transmitter (differential pressure measuring means) 40 Low pressure receiving housing (low pressure receiving part) 46 Operation part (operation means)

Claims (3)

[Claims] 1. A measuring tank to which a liquid to be measured for specific gravity is supplied, a high-pressure receiving section mounted below the measuring tank and receiving a hydraulic pressure, and a high-pressure difference H above the measuring tank. A low-pressure receiving portion mounted and receiving hydraulic pressure, a differential-pressure measuring means for detecting a differential pressure between the hydraulic pressure at the high-pressure receiving portion and the hydraulic pressure at the low-pressure receiving portion, Calculating means for calculating the specific gravity of the liquid based on the specific gravity. 2. A liquid pressure difference between a high-pressure receiving portion and a low-pressure receiving portion provided with a height difference H in a measuring tank to which a liquid to be measured as a specific gravity is fed, and the height difference H, A specific gravity measuring method characterized by determining a specific gravity. 3. In a chemical treatment step as a pretreatment before a photosensitive layer is formed on a support of a lithographic printing plate, a treatment liquid in a circulation tank is fed to a measurement tank, and a height difference H is set in the measurement tank. Lithographic printing, wherein the specific gravity of the processing liquid is determined from the pressure difference between the high and low pressure receiving sections provided and the height difference H to determine the specific gravity of the processing liquid and the concentration of the processing liquid in the circulation tank is controlled. Plate production method.