JP2008019116A - Method and equipment for automatically replenishing acid treatment liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To replenish automatically an acid treatment liquid prepared by mixing an acid and pure water so as to keep the concentration of the acid treatment liquid in a circulation tank, which tends to increase by evaporation, at a specific level. <P>SOLUTION: At a point of time when a liquid level sensor of an acid treatment liquid in a circulation tank detects a supply level, the concentration of the acid treatment liquid in the circulation tank is continuously measured. When the concentration is higher than specified concentration, pure water is supplied until the concentration of the acid treated liquid in the circulation tank reaches within a specified range. Then the acid and pure water are simultaneously supplied at a specified ratio calculated beforehand so as to be equal to the specified concentration of the acid treatment liquid in the circulation tank until the liquid level in the circulation tank reaches a supply stop level. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for controlling the concentration of an acid treatment liquid used for acid treatment of a glass plate surface and automatically replenishing the acid treatment liquid.

  Various stains and deposits may remain in the glass plate during the manufacturing process, but these deposits may become defects depending on the type, location, size, and purpose of use. It is necessary to remove by processing or the like.

  In particular, glass substrates used for flat panel displays such as plasma displays and liquid crystal displays also have defects on the film of traces of fine fallen objects, dross, tin, etc. adhering to the surface, so that normal acid treatment In order to remove dirt and deposits that cannot be removed, acid treatment with various acid treatment solutions is known. The concentration of the acid treatment solution in the tank is measured, and the result is based on the result. There are some known replenishers with acid treatment solutions.

  For example, Japanese Patent Application Laid-Open No. 2000-57953 discloses an automatic pre-acid treatment apparatus having a filter for filtering the hydrofluoric acid treatment liquid, which is an automatic supply apparatus for the hydrofluoric acid treatment liquid used in a glass cleaning process, and the filtration A concentration measuring device for measuring the concentration of hydrofluoric acid in the hydrofluoric acid treatment liquid, and a supply device for supplying the hydrofluoric acid to the hydrofluoric acid treatment liquid to a predetermined concentration based on the measured hydrofluoric acid concentration. An automatic supply device for hydrofluoric acid treatment liquid characterized by having an acid automatic concentration adjusting device is disclosed (Patent Document 1).

Further, in JP-A-7-258875, in the liquid quality control method in the circulation tank of the jet pickling equipment, when the steel strips having different descaling properties are pickled continuously, the traveling speed of the steel strip is A liquid quality control method in a circulation tank of a jet pickling facility having high responsiveness in adjusting the acid concentration in the circulation tank when changing is disclosed (Patent Document 2).
JP 2000-57953 A JP 7-258875 A

  Conventionally, in facilities that handle acid treatment liquids, pipes, tanks, and other peripheral equipment have been made of materials that do not corrode with acid treatment liquids. During acid treatment of glass plates in acid treatment equipment, There is a high risk that the atmosphere gas that has evaporated to workers near the glass plate inlet and outlet is adversely affected.

  For this reason, an acid equipment is supplied to the inlet and outlet of the acid treatment equipment, and the acid treatment equipment, and an exhaust equipment for exhausting the atmospheric gas in the circulation tank for collecting the acid-treated liquid is provided. It is necessary to discharge the atmospheric gas from which the processing liquid has evaporated. When the acid treatment liquid is nitric acid, etc., the components contained in the gas discharged from this exhaust system are mostly water, but the acid also evaporates depending on the concentration, temperature, etc. of the acid treatment liquid, and the amount varies. There is.

  In this way, the concentration of the acid treatment liquid in the circulation tank increases only by exhausting with the exhaust equipment, due to a decrease in moisture due to evaporation of the acid treatment liquid.

  When the glass plate is acid-treated with the acid treatment liquid and the glass plate is discharged, the acid treatment liquid is discharged on the glass surface, so the ratio of the acid treatment liquid carried out by the glass plate is the same as the acid treatment liquid. is there.

  The invention described in Patent Document 1 automates the maintenance and management of the hydrofluoric acid treatment liquid by incorporating an automatic analyzer into the concentration management work of the hydrofluoric acid treatment liquid used for the acid treatment of the glass panel. When measuring the concentration of the acid treatment solution tank, measure the concentration via the filter unit, wash the filter, and prepare a new treatment solution supply tank separately from the two acid treatment solution tanks. There was a problem that the facilities were large.

  In addition, the invention described in Patent Document 2 quickly corresponds to the acid concentration in the circulation tank when steel strips having different descaling properties are pickled continuously or when the traveling speed of the steel strip changes. Therefore, the hydrogen ion concentration, iron ion concentration, or liquid level of the acid solution is detected, and the waste acid, new acid, and pure water from the circulation tank are further determined based on the target values of each ion concentration required after a predetermined time. There is a problem that complicated control is required to control one of these and put it into each circulation tank.

  The present invention aims to solve the above problems, that is, while keeping the concentration of the acid treatment liquid in the tank constant and improving the productivity by replenishing the acid treatment liquid without stopping the acid treatment facility, The purpose is to keep the quality level of the glass plate by the acid treatment constant by making it possible to automatically replenish the acid treatment liquid which is dangerous in handling work and to make the acid treatment liquid of a predetermined concentration.

  That is, the present invention provides an acid treatment liquid composed of an acid and pure water, wherein the concentration of the acid treatment liquid whose concentration increases by evaporation is replenished in a constant and automatic manner in the circulation tank. When the acid level sensor detects the replenishment level, the concentration of the acid treatment liquid in the circulation tank is continuously measured, and when the concentration is higher than the set concentration, the concentration of the acid treatment liquid in the circulation tank. Is supplied at a predetermined ratio until the water concentration is within the set range, and then the high concentration acid stock solution and pure water are calculated in advance to be equal to the acid treatment solution set concentration in the circulation tank. At the same time, replenishment is performed until the liquid level in the circulation tank reaches the replenishment stop level.

  Alternatively, in the present invention, when the acid treatment liquid level in the circulation tank is between the lower limit level and the upper limit level, the concentration measurement of the acid treatment liquid is continuously performed, and the concentration of the acid treatment liquid is equal to or higher than a set value. Pure water is replenished until the concentration falls within the set range, and when the liquid level sensor detects the replenishment lower limit level, the liquid level of the circulation tank is determined at a predetermined ratio calculated in advance by calculation of the stock solution and pure water. Is an automatic replenishment method of an acid treatment solution, which is performed until a replenishment stop level is reached.

    Alternatively, in the present invention, the acid treatment liquid may be used for acid treatment of a surface of a glass substrate for a flat panel display such as a plasma display or a liquid crystal display, and nitric acid having a concentration of 18 vol% to 30 vol%. It is an automatic replenishment method of the above-mentioned acid treatment liquid characterized by using a nitric acid aqueous solution mixed with pure water.

  Alternatively, the present invention is an automatic replenishing device used in any of the above-described automatic replenishing methods of an acid treatment liquid, between an acid treatment chamber for acid-treating a glass plate surface and a circulation tank for supplying the acid treatment liquid. The acid treatment liquid circulating means for circulating the acid treatment liquid, the concentration measuring means for measuring the concentration of the acid treatment liquid in the circulation tank, and the raw solution supply for supplying the acid treatment liquid stock solution in the stock tank to the circulation tank Means, pure water supply means for supplying pure water in the pure water tank into the circulation tank, and exhaust means for exhausting atmospheric gas in the acid treatment chamber and the circulation tank, the liquid level of the circulation tank The controller controls the flow rate of the stock solution metering pump of the stock solution supply unit and the pure water metering pump of the pure water supply unit based on the signal and the measurement data by the concentration measuring unit, and the supply ratio of the acid treatment solution stock solution and the pure water is determined. control In an operational automatic supply device of the acid treatment solution for use in automatic replenishment process of the above-mentioned acid treatment solution, characterized in that the flow rate controlled so that the supply amount of the predetermined concentration.

  With a very simple configuration, the concentration of the non-volatile acid treatment liquid in the circulation tank can be automatically adjusted within the set range, and the acid treatment liquid to be replenished in the circulation tank can be easily purchased. Since it is a commercially available acid treatment liquid, the acid treatment liquid can be automatically replenished while operating the acid treatment equipment, and the acid treatment equipment is not stopped during the replenishment work of the acid treatment liquid.

  Thereby, the operator can ensure the safety of the operator without directly handling or touching the acid stock solution harmful to the human body.

  As shown in FIG. 1, the embodiment of the automatic replenishing device for acid treatment liquid of the present invention can store acid treatment equipment 1 for acid treatment of the glass plate G surface with acid treatment liquid and an acid treatment liquid of a predetermined concentration. A supply pipe 13 for supplying the acid treatment liquid and a recovery pipe 14 for collecting the acid treatment liquid are connected between the circulation tank 11 and the acid treatment liquid in the circulation tank 11 is supplied by the circulation pump 12 through the supply pipe 13. The remaining acid treatment liquid in the acid treatment equipment 1 after being supplied to the upper shower 2 and the lower shower 3 in the acid treatment equipment 1 and showering the acid treatment liquid on the glass substrate G conveyed by the conveyer 4 The liquid consists of acid treatment liquid circulating means 10 that recovers into the circulation tank 11 through the recovery pipe 14.

  Further, the acid treatment equipment 1 and the circulation tank 11 are provided with an exhaust equipment (not shown) for exhausting the atmospheric gas from which the acid treatment liquid has evaporated, and the circulation tank 11 has an upper limit level 16 of the liquid level of the acid treatment liquid. A sensor for detecting the replenishment level 17, the lower limit level 18, and the extreme upper limit level for preventing overflow is provided.

  Further, a stock solution tank 21 for storing the stock solution of the acid treatment solution and a pure water tank 31 for storing pure water are disposed in the vicinity of the circulation tank 11, and supply pipes are circulated from the stock solution tank 21 and the pure water tank 31, respectively. Connected to the tank 11, a raw solution supply means 20 for supplying the stock solution of the acid treatment solution in the stock solution tank 21 to the circulation tank 11 by the stock solution metering pump 22, and pure water in the pure water tank 31 to the pure water metering pump 32. The pure water supply means 30 which supplies in the circulation tank 11 by this was provided.

  Further, as a concentration measuring means for measuring the concentration of the acid treatment liquid in the circulation tank 11, a conductivity meter 41 is provided that uses an electrode rod 42 immersed in the acid treatment liquid as a sensor. Exhaust means (not shown) for exhausting the atmospheric gas in the tank 11 was provided.

  The liquid level signal of the circulation tank 11 and the measurement data by the conductivity meter 41 of the concentration measuring means 40 are input to a controller (not shown), and the controller controls the stock solution metering pump 22 of the stock solution supply means 20 and the pure water supply means 30. The ON / OFF control of the pure water metering pump 32 is performed, the supply ratio of the acid treatment liquid stock solution to the pure water is calculated by the controller, and the supply amount of a predetermined concentration which is the set concentration of the acid treatment liquid in the circulation tank is obtained. Control the flow rate.

  The acid treatment equipment 1, the circulation tank 11, the stock solution tank 21, the supply pipe 13, and the recovery pipe 14 are made of a material that does not corrode by the acid treatment liquid. For example, in the case of nitric acid, it is made of stainless steel or resin.

  The following is an embodiment of a method for automatically replenishing the acid treatment liquid into the circulation tank 11 while keeping the concentration of the acid treatment liquid in the circulation tank 11 constant.

  The acid treatment liquid automatic replenishment method according to the first embodiment is an acid treatment liquid composed of acid and pure water, and the concentration in the circulation tank 11 of the acid treatment liquid whose concentration increases by evaporation is constant, In the automatic replenishment method, when the acid level sensor of the acid treatment liquid in the circulation tank 11 detects the replenishment level 17, the concentration of the acid treatment liquid in the circulation tank 11 is continuously measured and set. When the concentration is higher than the concentration, pure water is replenished until the concentration of the acid treatment liquid in the circulation tank 11 falls within the set range, and then the stock solution of pure acid and pure water with a high concentration are preliminarily calculated. In this method, replenishment is performed until the liquid level of the circulation tank 11 reaches the upper limit level 16 at a predetermined ratio calculated so as to obtain the set concentration of the acid treatment liquid.

As the second embodiment, the acid treatment liquid level in the circulation tank 11 is between the lower limit level 18 and the upper limit level 16, and the concentration of the acid treatment liquid is continuously measured. When above the set value, replenish the pure water until the concentration falls within the set range,
Further, when the liquid level sensor detects the replenishment level 17, the liquid level of the circulation tank 11 is calculated at a predetermined ratio calculated in advance so that the stock solution and the pure water become the set concentration of the acid treatment liquid in the circulation tank 11 by calculation. Is performed until the upper limit level 16 is reached.

  The acid treatment liquid is an acid treatment liquid in which pure water is mixed with an acid such as an aqueous nitric acid solution used for acid treatment of the surface of a glass substrate for a flat panel display such as a plasma display or a liquid crystal display to be conveyed. The concentration is preferably 18 vol% to 30 vol%, and the treatment liquid is preferably 40 ° C. to 50 ° C.

  Next, the operation of the present invention will be described.

  When the acid treatment liquid in the circulation tank 11 needs to be replenished, the concentration of the acid treatment liquid in the circulation tank 11 is first measured and only pure water is replenished first, for example with nitric acid. In the case of the acid treatment liquid, most of the evaporation of the acid treatment liquid contained in the atmospheric gas in the circulation tank 11 or the acid treatment facility 1 due to the evaporation of the acid treatment liquid is moisture, and the evaporation amount of nitric acid or the like is Since the concentration of the acid treatment liquid changes to a concentration higher than the predetermined concentration, the concentration of the acid treatment liquid is first returned to the predetermined concentration range by replenishing the circulation tank 11 with pure water. is there.

  After that, the pure water and the acid treatment liquid stock solution were replenished at a predetermined ratio at the same time until the liquid level of the circulation tank 11 reached the upper limit level 16. Even if it is replenished, the concentration of the acid treatment liquid in the circulation tank 11 fluctuates greatly, and it takes time to return to a predetermined concentration by replenishing pure water, and the control becomes complicated.

  In particular, when only the stock solution of the acid treatment liquid having a high concentration is supplied in a state where the liquid level is just before the upper limit level 16 of the circulation tank 11, even if it is necessary to supply pure water thereafter, the upper limit level is detected to supply pure water. This is because density cannot be adjusted.

  The concentration of the acid treatment liquid is set to 18 vol% or more and less than 30 vol% because the concentration of the acid treatment liquid is 18 vol% or more in order to remove dirt such as adhering matter or falling matter attached to the glass substrate G. On the contrary, the acid treatment solution having a high concentration of 30 vol% or more not only increases the cost of the acid treatment solution itself, but also may cause adverse effects such as corrosion on the equipment. This is because when the operator accidentally contacts the acid treatment liquid adhering to the liquid tank or the like, the higher the concentration, the greater the danger and the handling becomes difficult.

  In addition, the temperature of the acid treatment solution is heated to about 40 ° C. to remove dirt and deposits such as minute falling matter, dross, tin, etc. attached to the surface of the glass substrate G. However, if the acid treatment liquid is heated to around 40 ° C., the removal of dirt is faster, and it can be removed more cleanly than in the case of treatment at room temperature, but if the heating temperature is further increased, Instead of cleaning it cleanly, the piping material that supplies the acid treatment liquid and the material used for the acid treatment equipment cannot be used with resin-based materials, which increases the corrosion of the equipment, and there is a safety problem. Further, the concentration of the acid treatment liquid, particularly the evaporation of water, increases and the concentration changes, which is not preferable.

Example 1 As shown in FIG. 1, a circulation tank 11 storing a nitric acid aqueous solution heated to 40 ° C. with a volume concentration of 3 N (18 vol%), and connected to the circulation tank 11 and commercially available as industrial nitric acid. The nitric acid stock solution tank 21 storing nitric acid having a concentration of 67.5 vol% and the pure water tank 31 connected to the circulation tank 11 and storing pure water are used for a glass substrate G used for PDP, liquid crystal, etc. Arranged in the vicinity of the acid treatment facility 1.

  In the circulation tank 11, the upper limit level (not shown) for preventing the overflow of the acid treatment liquid from the upper end side, the upper limit level 16 with the upper limit of replenishment of the acid treatment liquid, and the start of replenishment of the acid treatment liquid are detected. A sensor capable of detecting the replenishment level 17 and the lower limit level 18 of the acid treatment liquid was provided.

  The acid treatment liquid in the circulation tank 11 is showered by an acid treatment liquid composed of nitric acid having a concentration of 3 N (18 vol%) on the upper surface side and the lower surface side of the glass plate G conveyed in the acid treatment facility 1 by a circulation pump. The residual liquid that has been treated and showered on the glass plate G in the acid treatment facility 1 is collected in the circulation tank 11.

  Also, a 67.5 vol% nitric acid stock solution in the nitric acid stock solution tank 21 is supplied into the circulation tank 11 by a metering pump, and pure water in the pure water tank 31 is supplied into the circulation tank 11 by a metering pump.

  Another exhaust gas treatment (not shown) is performed by an exhaust means (not shown) so that the atmosphere gas evaporated from the acid treatment liquid does not leak from the opening side and the opening side of the glass plate G to be acid treated in the acid treatment facility 1. Similarly, the atmosphere gas evaporated in the circulation tank 11 was also discharged by an exhaust means (not shown).

In order to measure the concentration of the liquid in the circulation tank 11, an electrode bar of a conductivity meter is set in the liquid surface. For example, when a nitric acid solution having a concentration of 18 vol% was measured with a conductivity meter, a measured value of 700 millisiemens (msc) / cm was obtained. When this value is converted into a concentration, it becomes 3 regulations (18 vol%). This was confirmed by titration analysis.

The acid treatment liquid in the circulation tank 11 is circulated to the acid treatment facility 1, and the acid treatment is performed when the level of the acid treatment liquid in the circulation tank 11 reaches the replenishment level 17 during the acid treatment of the glass plate G. Start replenishing the liquid.

  First, the concentration of the acid treatment liquid in the circulation tank 11 was measured, and since the concentration of the acid treatment liquid was high, pure water was replenished until a predetermined concentration was reached.

  Subsequently, 67.5 vol% (15.2 N) of industrial nitric acid and pure water, which is a stock solution of the acid treatment liquid, are simultaneously supplied into the circulation tank 11 at a ratio of 1: 4, and 3N (normative). The acid treatment solution was replenished until the upper limit level 16 that is the replenishment stop level was detected by the sensor.

  Thereby, it can replenish, making the density | concentration of the acid treatment liquid of the nitric acid aqueous solution in the circulation tank 11 constant, operating, without stopping the acid treatment equipment 1 of a glass plate.

[Example 2]
The equipment used in Example 2 is performed using the same equipment as that described in Example 1. When the acid treatment liquid level in the circulation tank 11 is between the lower limit level 18 and the upper limit level 16, the concentration of the acid treatment liquid is continuously measured, and when the concentration of the acid treatment liquid is equal to or higher than a set value, the concentration is Supply the pure water until it is within the set range,
Further, when the liquid level sensor detects the replenishment level 17, it is performed until the liquid level of the circulation tank 11 reaches the upper limit level 16 at a predetermined ratio calculated so that the stock solution and pure water have a preset concentration by calculation in advance. .

  The preferred embodiment has been described above, but the present invention is not limited to this.

Schematic which showed the whole structure of the acid treatment equipment of this invention.

Explanation of symbols

G glass substrate 1 acid treatment equipment 2 upper shower 3 lower shower 4 transport conveyor 10 acid treatment liquid circulation means 11 circulation tank 12 circulation pump 13 supply pipe 14 recovery pipe 16 upper limit level 17 replenishment level 18 lower limit level 20 stock solution supply means 21 Stock solution tank 22 Metering pump 30 Pure water supply means 31 Pure water tank 32 Metering pump 40 Concentration measuring means 41 Conductivity meter 42 Electrode bar

Claims (4)

An acid treatment liquid in which acid and pure water are mixed, and the concentration of the acid treatment liquid whose concentration increases by evaporation is maintained constant, and the acid and pure water are automatically supplied to the circulation tank. In the method, when the level sensor of the acid treatment liquid in the circulation tank detects the replenishment level, the concentration of the acid treatment liquid in the circulation tank is continuously measured, and when the concentration is higher than the set concentration, the circulation tank The pure water is replenished until the concentration of the acid treatment liquid within the set range is reached, and then the acid and the pure water are calculated in advance so as to be equal to the set concentration of the acid treatment liquid in the circulation tank. An acid replenishment liquid automatic replenishment method, wherein acid and pure water are replenished at a ratio at the same time until the liquid level in the circulation tank reaches a replenishment stop level. When the acid treatment liquid level in the circulation tank is between the lower limit level and the upper limit level, the concentration of the acid treatment liquid is continuously measured, and when the concentration of the acid treatment liquid is equal to or higher than the set value, the concentration is within the set range. When the water level sensor detects the replenishment lower limit level, the liquid level in the circulation tank reaches the replenishment stop level at a predetermined ratio calculated in advance for the stock solution and pure water. An automatic replenishment method of an acid treatment liquid, which is performed until The acid treatment liquid is a nitric acid aqueous solution in which nitric acid having a concentration of 18 vol% to 30 vol% used for acid treatment of the surface of a glass substrate for a flat panel display such as a plasma display or a liquid crystal display to be transported is mixed with pure water. The method for automatically replenishing an acid treatment liquid according to claim 1 or 2, wherein: It is an automatic replenishment apparatus used for the automatic replenishment method of the acid treatment liquid in any one of the said Claim 1 thru | or 3, Comprising: Between the acid treatment chamber which acid-treats a glass plate surface, and the circulation tank which supplies an acid treatment liquid Acid treatment liquid circulation means for circulating the acid treatment liquid, concentration measurement means for measuring the concentration of the acid treatment liquid in the circulation tank, and raw solution supply means for supplying the acid treatment liquid stock solution in the raw solution tank to the circulation tank A pure water supply means for supplying pure water in the pure water tank into the circulation tank, and an exhaust means for exhausting the atmosphere gas in the acid treatment chamber and the circulation tank, and a liquid level signal of the circulation tank, The controller controls the flow rate of the stock solution metering pump of the stock solution supply unit and the pure water metering pump of the pure water supply unit based on the measurement data obtained by the concentration measuring unit, and the controller supplies the supply ratio of the acid treatment solution stock solution to the pure water. Calculate Automatic replenishment device for the acid treatment solution for use in automatic replenishment process of acid treatment solution, characterized in that the flow rate controlled so that the supply amount of the constant concentration.

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