JPH04202028A - Method of cleaning plate glass - Google Patents

Abstract

PURPOSE:To easily treat waste liquid without requiring a large-scale facilitates and to easily remove tin deposition by bringing a float plate glass into contact with a specified acid soln., and then washing the glass by using a physical stripping means to remove the tin deposition. CONSTITUTION:Plural sheets of float glass 4 are arranged in a stand 5, transferred with a hanging means 6 into an acid treatment tank 1 and maintained therein at proper temp. for proper time, for example, at about 50 deg.C for about 10min. Then the glass 4 is pulled out, carried and once dipped in a water tank 7 as arranged in the stand in order to suppress harmful effect of the acid on the succeeding processes. Then the stand 5 is mounted on a table 8 with the hanging means 6, and the plate glass sheets 4 are successively transferred to carrier rollers 9 and carried to a washing tank 10. The glass is then sent to a roller conveyer 11 in the tank 10 where the glass is washed with water from shower heads 12, 12 provided above and under the conveyer. At same time, the glass is brushed with a scratching means such as brush rollers 13, 13 to remove tin deposition.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for cleaning float plate glass, that is, plate glass manufactured by the float plate manufacturing method, and in particular to a method for peeling off and removing tin adhering to the surface of the plate glass during the plate manufacturing process. Concerning an effective method for cleaning plate glass.

[Prior art and its problems]

During the sheet-making process, float plate glass has a bottom surface that is in contact with the tin bath (
Tin residue, or dross, adheres to the bottom surface (referred to as the bottom surface), and top speck, which is tin vapor that has fallen as droplets and solidified, adheres to the upper surface that is in contact with the atmosphere (referred to as the top surface), and depending on the size etc. There are many cases where tin cannot be used due to defects.

Conventionally, window glass for buildings and automobiles, etc., has been used as a product if tin deposits are barely visible and the size, number, and distribution are within specified limits, but in recent years demand has increased. In the field of electronic materials, such as display materials, where tin deposits are rapidly increasing, even minute tin deposits that are difficult to see with the naked eye are excluded as defects.

It is well known that nitric acid, which has a strong ability to dissolve and eliminate tin, is used to remove adhering tin on plate glass.On the other hand, sulfuric acid and hydrochloric acid have a weak dissolving effect (therefore, conventional attempts to use these have been unsuccessful). has not been done.

For example, JP-A-2-88445 discloses treating a glass plate at a relatively high temperature using a relatively high concentration nitric acid and hydrochloric acid mixture, but these mixed acids themselves have high vapor pressures. Since the gas is easily generated and volatilized, there are problems such as the need to make the equipment large and strong to ensure perfect airtightness of the acid treatment tank, and the need for gas suction removal equipment. It is not easy to convert these acids into solid compounds and remove them by precipitation.

Of course, the processing liquid itself is not cheap, and these equipment and processing liquid increase the overall cleaning cost.

It is an object of the present invention to solve the above-mentioned problems, and to provide a method for cleaning plate glass, which uses a cheap processing solution, makes waste liquid treatment easy, does not require large-scale equipment, and can easily remove tin deposits. It is in.

[Means for Solving the Problems 1] The present invention provides a method in which a float plate glass is brought into contact with an acid solution and then washed with water to remove adhering tin. These mixed acids are used together with a physical peeling means when washing with water, or when a physical peeling means is used together with the acid treatment. It consists of injecting a stream or applying ultrasonic vibrations to the liquid.

For the contact of the plate glass with the acid solution, methods such as immersing the plate glass in the dilute sulfuric acid, etc., or casting dilute sulfuric acid, etc. on the plate glass can be adopted, and of course, as a result, it is possible to reduce the amount of water that adheres to the plate glass. It also has the effect of dissolving and eliminating fine tin, but
At the same time, there is a point to be noted in that it exhibits a physical action that facilitates the peeling and removal of coarser tin.

This is presumably due to the fact that dilute sulfuric acid, dilute hydrochloric acid, or a mixed acid thereof has a different dissolution mechanism from other acids such as nitric acid, but the details are unknown.

In addition, when the plate glass comes into contact with the acid solution, if dilute sulfuric acid or the like is injected at high speed onto the plate glass surface, and of course the acid is circulated or other means is adopted and the injection is continued for the required time, tin can be removed by the acid itself. In addition to the effect of facilitating peeling, the physical peeling effect of the jet flow is also added.

Physical peeling means may include high-speed spraying of the acid solution or water during cleaning, or rubbing the plate glass surface with brushing, puff friction, etc. during the acid treatment or water washing process, or removing these during the acid treatment or water washing process. At least one or more of the following methods are employed, such as applying ultrasonic vibration to the liquid.

The present invention will be explained below based on examples.

[Example] Attached Figure 1 is a schematic side sectional view showing an example of the cleaning method of the present invention according to its flow, and 1 is an acid treatment tank having a heater 2 and storing a 2wtx sulfuric acid aqueous solution 3. be.

The nucleic acid processing tank 1 may be provided with stirring means if necessary.

A plurality of float glass plates 4 are placed on a pedestal 5, and then the pedestal 5 is transferred by a known suspension means 6, which is partially shown, and immersed in the acid treatment tank 1, where it is heated to an appropriate temperature, e.g. Hold at about 50°C for an appropriate time, for example about 10 minutes.

Then, after being lifted and carried out, it is immersed in a water tank 7 as it is to suppress the harmful effects of acid in subsequent operations, but the water tank 7 may be provided with an appropriate membrane as necessary, and is not essential.

Further, the pedestal 5 is placed on the table 8 by the suspension means 6, and the plate glasses 4 are sequentially transferred to the conveying rollers 9 and carried into the cleaning tank 10.
1, the upper and lower showers 12 are gradually sent out;
3. Remove tin and wash by brushing in step 13.

The brush roller 13.13 is made of a steel core material with fibers such as nylon implanted radially, and its rotation speed is, for example, 200 PPM, and the passage time of the plate glass 4 in the cleaning tank 10 is from several seconds to 1 minute or less. It is assumed that the

Thereafter, water is drained using air injection means 14, 14, and drying or other appropriate means (not shown) are employed to complete the cleaning of the glass plate 4.

As described above, the rubbing means may be, for example, puff friction, and these rubbing means can also be employed in the acid treatment tank.

Further, various physical peeling means such as ultrasonic means or the like can be employed in the acid treatment tank or the cleaning tank.

Below, in the preliminary test, 150mm opening x 1.2mm
Thick sheet glass is immersed in various acids at a predetermined temperature for a predetermined time, and then taken out and washed with water at approximately 20 ORPM.
It takes about 5 seconds to pass between a pair of upper and lower blacks rotating at
After drying, the size and number of tin-attached residues were measured under a microscope, and the results are shown in Table 1. In the table, E1 to E5 are examples, CE1
-CE2 are comparative examples.

As is clear from the table, good results were obtained within the scope of the present invention, while none of the comparative examples could achieve the intended purpose.

Table 1 This value is the size of the tin defect - mmφ, and the value in parentheses is the number [Effect 1 of the invention] According to the present invention, tin deposits on a glass plate can be easily removed with a simple configuration, and it is suitable for architectural use. It has the advantage that it can be applied not only to window glass but also to materials for electronic materials, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view showing an example of the cleaning method of the present invention according to its flow. 1-11 Acid treatment tank 3---Sulfuric acid aqueous solution 4-111 Float plate glass 7---Water tank 10---Cleaning tank 12.12---Shower 13.13---- Brush roller 5 tips recommended

Claims (1)

[Claims] 1) A method of contacting a float plate glass with an acid solution and then washing it with water to remove adhering tin, wherein the acid solution consists of dilute sulfuric acid, dilute hydrochloric acid, or a mixed acid thereof at room temperature to slightly high temperature, and the washing with water A method for cleaning plate glass characterized by using physical peeling means in combination. 2) In the method of contacting float plate glass with an acid solution and then washing it with water to remove adhering tin, the acid solution consists of dilute sulfuric acid, dilute hydrochloric acid, or a mixed acid thereof at room temperature to slightly high temperature, and physical peeling occurs during acid treatment. A method for cleaning plate glass characterized by the combined use of a method. 3) The sheet glass according to claim 1 or 2, wherein the physical peeling means comprises rubbing the sheet glass surface, jetting a high-speed flow of liquid onto the sheet glass surface, or applying ultrasonic vibration to the liquid. Cleaning method.