TW201708150A - Method of removing metallic deposits from glass - Google Patents

Abstract

A method of removing metallic deposits from a glass article, for example a glass substrate such as a glass sheet, includes exposing the glass article to a weak acid solution for a time effective to remove the metallic deposit.

Description

Method of removing metal deposits from glass

The present invention relates to a method of treating glass articles, such as glass substrates, such as glass sheets suitable for use in display applications, and more particularly to a method for treating glass articles from glass articles. A method of removing metal deposits.

A glass substrate suitable for use in display applications can be, for example, a substrate in a glass display panel or a protective glass sheet for a display panel. These glass substrates must be very clean and free of defects, because for these displays even the small defects on the screen, the visual acuity of the viewer can be perceived. In addition, the contaminants of the glass sheets used in these applications can hinder the deposition and/or action of the materials, and the materials deposited on the glass sheets are required for normal operation of the display elements. For example, contaminants can hinder the deposition of thin film transistors that are deposited on one or more glass substrates used to fabricate display devices.

The contaminants of the glass substrate may be, for example, organic or metallic materials. Since no single cleaning material can remove all of these contaminants, the process needs to be adjusted to use different cleaning agents to remove different contaminants. Even so, there is still a need for glass sheet manufacturing cost limitations, thus requiring an efficient method that does not significantly increase process cost and remove contaminants from the glass sheets.

The present inventors have discovered that weak acids can be used to treat glass articles, such as glass substrates, for example, glass sheets containing metal deposits on the surface, and it has been demonstrated that glass materials can be effectively treated even at very low concentrations, even at weak concentrations. Furthermore, in some specific examples, the use of hypochlorous acid from industrial water systems to provide a ready-made source of chlorinated water is advantageous because: 1) the above sources are abundant and inexpensive, and 2) the above sources are not Limited to special treatments requiring more active acid such as sulfuric acid or hydrochloric acid. Hypochlorous acid is widely used as a bleaching agent and deodorant, as well as for disinfecting and preventing the growth of bacteria in water. For example, hypochlorous acid can be used in industrial applications to prevent bacteria from growing in water as a cooling fluid in a heat exchange system. Hypochlorous acid can be easily produced, for example, by adding sodium chlorite to water to produce hypochlorous acid.

Accordingly, one aspect of the present invention is to describe a method of removing metal deposits from a glass article with a weak acid. The method includes exposing the glass article to a weak acid aqueous solution having a concentration of between 0.5 and 1.0 ppm for a period of time to effectively remove metal deposits from the surface of the glass article. The solution of a weak acid dissociation constant K can be between about _a range of between 2.95 x 10 ^-8 to about 7.5 x 10 ^-3. For example, the weak acid can be selected from the group consisting of hypochlorous acid, boric acid, and phosphoric acid. The metal deposit may comprise at least one of iron, calcium, barium, zinc, cobalt, manganese, cerium, and combinations or alloys thereof. In various specific embodiments, the metal deposit comprises iron and the weak acid comprises hypochlorous acid.

Another aspect of the invention is a method of removing metal deposits from a glass sheet. The method includes exposing the entirety of at least one major surface of the glass sheet to a hypochloric acid aqueous solution having a concentration of between 0.5 and 1.0 ppm for a period of time to effectively remove metal deposits from at least one major surface. The metal deposit may include at least one of iron, calcium, barium, zinc, cobalt, manganese, cerium, and combinations or alloys thereof.

It should be clearly understood that while the present invention is generally directed to glass substrates (e.g., glass sheets) fabricated in a glass sheet process, the specific examples described herein can be applied to other glass articles. Thus, the invention is not limited to glass sheets, glass sheets or other glass substrates, and the invention may also be used to remove metal deposits from conventional glass articles, regardless of the shape of the glass.

It is to be understood that the foregoing general description of the embodiments of the invention and The drawings are provided to provide a further understanding of the specific embodiments, which are incorporated in and constitute a part of the specification. The drawings illustrate various specific embodiments of the invention, and are in the

The apparatus and method will now be described more fully with reference to the exemplary embodiments of the invention presented in the drawings. Whenever possible, the same reference numbers are used in the drawings in the drawings. However, the disclosure of the present invention can be embodied in many different forms and should not be construed as limited to the specific examples described herein.

It is to be understood that the specific embodiments disclosed may be described in the specific features, elements or steps described in connection with the particular embodiments. It is also to be understood that the specific features, elements, or methods may be described in the various combinations and modifications of the various combinations and modifications.

Ranges may be expressed as "about" a particular value and/or to "about" another particular value. When such a range is indicated, another specific example includes from a particular value and/or to another specific value. Similarly, when the antecedent "about" is used to mean that the value is an approximation, it is understood that It should also be understood that it is meaningful that the endpoint of each range is related to another endpoint or to another endpoint.

The directional terms used herein, such as top, bottom, right, left, front, back, top, and bottom, are merely referenced to the drawing, and are not intended to imply absolute directions.

Unless otherwise expressly stated, it is not intended that any of the methods described herein be construed as being in a Therefore, the method request item does not actually record that these steps are subject to a certain order, or that any device request item does not actually record the order or direction of the individual components, or there is no specific specification in the scope of the patent application or the specification to limit these steps. The specific order or orientation of the various components of the device is not described in the specific order, and thus is not intended to infer a certain order or orientation. This applies to any possible unrepresented basis for interpretation, including: logical matters relating to step configuration, operational flow, component sequence or component orientation; general implications derived from grammatical organization or punctuation; and specific examples described in the specification The quantity or type.

The singular forms "a" and "the" Therefore, unless the context clearly dictates otherwise, for example, reference to "a" member includes the s

An example glass manufacturing apparatus 10 is illustrated in FIG. In some embodiments, the glass making apparatus 10 can include a glass melting furnace 12 that can include a melting tank 14. In addition to the melting tank 14, the glass melting furnace 12 can optionally include one or more additional components, such as heating elements (eg, burners or electrodes), configured to be batch heated and batch converted to molten glass. In a further embodiment, the glass melting furnace 12 can include a heat treatment device (eg, an insulating member) configured to reduce heat loss around the melting tank. In a further embodiment, the glass melting furnace 12 can include an electronic device and/or an electromechanical device configured to facilitate melting of the batch material into a glass melt. Still further, the glass melting furnace 12 can include a support structure (eg, a support chassis, a support, etc.) or other components.

The glass melting tank 14 is typically composed of a refractory material, such as a refractory ceramic material. In some embodiments, the glass melting tank 14 may be constructed of refractory ceramic tiles, such as refractory ceramic tiles comprising alumina or zirconia.

In certain embodiments, a glass melting furnace can be incorporated as a component of a glass manufacturing apparatus configured to make a glass ribbon. In some embodiments, the glass melting furnace of the present invention may be incorporated as a component of a glass manufacturing apparatus comprising a slot draw apparatus, a float bath apparatus, a pull down apparatus (eg, a fusion apparatus), Pull-up device, press roll device, tube drawing apparatus or any other glass manufacturing equipment. By way of example and not limitation, FIG. 1 is a schematic illustration of a glass-melting furnace 12 as a component of a fused glass manufacturing apparatus 10 for fusing a glass ribbon for fusing, and then for glass. The tape is subjected to subsequent processing to form a glass sheet.

The glass making apparatus 10 (eg, the fusion pull down apparatus 10) optionally includes an upstream glass making apparatus 16 disposed upstream of the glass melting tank 14. In some embodiments, one or the entirety of the upstream glass making apparatus 16 may be incorporated as part of the glass melting furnace 12.

As shown in the illustrated embodiment, the upstream glass manufacturing apparatus 16 can include a storage container 18, a batch delivery device 20, and a motor 22 coupled to the batch delivery device. The storage container 18 can be configured to store a quantity of batch material 24 and to feed a quantity of batch material 24 into the melting tank 14 of the glass melting furnace 12 as indicated by arrow 26. In some embodiments, the batch delivery device 20 can be powered by the motor 22 such that the configured batch delivery device 20 can deliver a predetermined amount of batch material 24 from the storage container 18 to the melting tank 14. In a further embodiment, the motor 22 can supply power to the batch conveyor 20 at a controlled rate based on the level of molten glass sensed downstream from the melt tank 14 to introduce the batch material 24. Thereafter, the batch material 24 in the melting tank 14 can be heated to form the molten glass 28.

The glass making apparatus 10 may also optionally include a downstream glass making apparatus 30 disposed downstream of the glass melting furnace 12. In some embodiments, a portion of the downstream glass making apparatus 30 can be incorporated as part of the glass melting furnace 12. For example, the first connecting conduit 32 discussed below or other portions of the downstream glass making apparatus 30 may be incorporated as part of the glass melting furnace 12. The components of the downstream glass making equipment include a first connecting conduit 32 that may be constructed of a precious metal. Suitable noble metals include platinum group metals selected from the group consisting of platinum, rhodium, ruthenium, osmium, iridium, and palladium or alloys of the foregoing. For example, the downstream member of the glass making apparatus may be composed of a platinum-rhodium alloy including 70 to 90% by weight of platinum and 10 to 30% by weight of ruthenium. However, other suitable metals include molybdenum, palladium, rhodium, iridium, titanium, tungsten, and the alloys described above.

The downstream glass making apparatus 30 includes a first conditioning tank (ie, a first processing tank), such as a clarification tank 34. The clarification tank 34 is located downstream of the smelting tank 14 and is coupled to the smelting tank 14 via the first connecting conduit 32 mentioned above. In some embodiments, the molten glass 28 can be gravity fed from the melting tank 14 through the first connecting conduit 32 to the clarification tank 34. For example, gravity can drive the molten glass 28 from the melt tank 14 through the internal passage of the first connecting conduit 32 to the clarification tank 34. However, it should be understood that other conditioning slots may be disposed downstream of the melting tank 14, such as between the melting tank 14 and the clarification tank 34. In some embodiments, a cooling tank (not shown) may be employed between the melting tank and the clarification tank, wherein the cooling glass cools the molten glass from the melting tank to a low temperature before entering the clarification tank. The temperature of the molten glass in the melting tank.

Within the clarification tank 34, bubbles can be removed from the molten glass 28 by various techniques. For example, batch material 24 can include a multivalent compound (i.e., a fining agent), such as tin oxide, which can undergo a chemical reduction reaction upon heating and release oxygen. Other suitable fining agents include, but are not limited to, arsenic, antimony, iron, and antimony. The clarification tank 34 is heated to a temperature higher than the melting tank to heat the clarifying agent. The oxygen bubbles generated by the chemical reduction reaction of the clarifying agent through the temperature rise up through the molten glass in the clarification tank, wherein the gas in the melt produced in the melting furnace can be combined with the oxygen bubbles generated by the clarifying agent. In the clarification tank, the enlarged bubbles can rise to the free surface of the molten glass and then be discharged.

The downstream glass making apparatus 30 may further include a second conditioning tank, such as a mixing tank 36 for mixing molten glass, which may be located downstream of the clarification tank 34. The glass melt mixing tank 36 can be used to provide a homogeneous glass melt composition to reduce or eliminate the heterogeneity that can otherwise be present in the clarified molten glass exiting the clarification tank. As shown, the clarification tank 34 can be coupled to the mixing tank 36 of molten glass via a second connecting conduit 38. In some embodiments, the molten glass 28 can be gravity fed from the clarification tank 34 to the mixing tank 36 via the second connecting conduit 38. For example, gravity can drive the molten glass 28 from the clarification tank 34 through the internal passage of the second connecting conduit 38 to the mixing tank 36. It should be noted that although the mixing tank 36 is shown downstream of the clarification tank 34, the mixing tank 36 may also be disposed upstream of the clarification tank 34. In some embodiments, the downstream glass making apparatus 30 can include a plurality of mixing tanks, such as a mixing tank upstream of the clarification tank 34 and a mixing tank downstream of the clarification tank 34. These multiple mixing tanks may be of the same design or may be of a different design than each other.

The downstream glass making apparatus 30 may further include another conditioning tank, such as a trough 40 that may be located downstream of the mixing tank 36. The trough 40 can condition the molten glass 28 for feeding into the downstream forming apparatus. For example, the trough 40 can act as an accumulator and/or flow controller to regulate and provide a consistent flow of molten glass 28 to the shaped body 42 via the outlet conduit 44. As shown, the mixing tank 36 can be coupled to the trough 40 via a third connecting conduit 46. In some embodiments, the molten glass 28 can be gravity fed from the mixing tank 36 to the trough 40 via a third connecting conduit 46. For example, gravity can drive the molten glass 28 from the mixing tank 36 through the internal passage of the third connecting conduit 46 to the trough 40.

The downstream glass making apparatus 30 may further comprise a forming apparatus 48 comprising the above-mentioned shaped body 42 and the shaped body 42 comprising an inlet duct 50. The outlet conduit 44 can be configured to deliver molten glass 28 from the trough 40 to the inlet conduit 50 of the forming apparatus 48. In the fusion molding process, the molded body 42 may include a trough 52 disposed in the upper surface of the molded body and the converging forming surface 54 along the bottom edge of the molded body (root) ) 56 gathering. The molten glass conveyed to the groove of the molded body through the conveying groove 40, the outlet pipe 44, and the inlet duct 50 overflows the groove wall and moves downward along the converging forming surface 54 as a separated flow of the molten glass. The separated flow of molten glass joins under the root and creates a single glass ribbon 58 along the root, which is pulled from the root 56 by applying tension to the glass ribbon, such as by gravity and pulling rolls (not shown). 58, to control the size of the glass ribbon as the glass cools and the viscosity increases, such that the glass ribbon 58 undergoes a viscous-elastic transition and has mechanical properties that impart a dimensional stability characteristic to the glass ribbon 58. The glass ribbon can then be separated into individual glass substrates 59 by a glass separation device (not shown).

It should be understood that the production of glass substrates suitable for sale and distribution to equipment manufacturers requires additional processing before the products can be shipped from the manufacturer. Thus, FIG. 2 depicts an exemplary finishing line 60 disposed downstream of the glass manufacturing apparatus 10. Processing line 60 may include a variety of different stations that are configured to process one or more glass substrates 59, including one or more cutting stations 62, beveling stations 64, washing stations 66. The detection station 68 and the packaging station 70.

In the first step of the exemplary processing line 60, the glass substrate 59 can be cut to a predetermined size. For example, the larger glass ribbon 58 produced by the above apparatus 10 is cut into a glass substrate having a predetermined size. In various embodiments, the glass ribbon can be a continuous glass ribbon that is cut in a direction substantially perpendicular to the length dimension of the glass ribbon (eg, perpendicular to the drawing direction). The glass substrate 59 can comprise a thickness ranging from about 0.05 to about 0.7 mm, such as between about 0.1 mm to about 3 mm, between about 0.3 mm to about 1 mm, and between about 0.5 mm to about 0.7 mm. And include all ranges and subranges between them. In many operations of pulling a glass ribbon, the edge of the glass ribbon is thickened due to the width-wise shrinkage of the glass ribbon as it is cooled from the viscous state to the elastic state, and the thickened edge portion is thickened. Called bead. However, typical applications, such as the fabrication of display panels for incorporation into various display devices, require the removal of these beads. In addition, the mother glass substrate cut from the glass ribbon can be further cut into several smaller glass substrates. Thus, the glass substrate 59 can be processed at the cutting station 62, which can perform a cutting operation to remove any edge portion beads present on the glass substrate, and optionally cut the glass substrate to a predetermined size.

Once the glass substrate 59 has been trimmed to remove the beads and/or cut to a predetermined size, the edges of the glass substrate can be beveled at the beveling station 64. Any one or more edges of the glass substrate can be beveled. In various embodiments, all four edges of the rectangular substrate can be beveled individually (one at a time) or simultaneously. The cutting process removes damaged edge faces on the glass substrate. For example, mechanical scoring and breaking processes typically involve contact of the major surface of the glass substrate with the scoring tool. The contact requires sufficient force to press the scoring tool into the glass substrate to create an open crack that extends at least partially through the thickness of the glass substrate. At least a portion of the thickness of the glass substrate is also damaged by forced contact with the scoring tool. This damage provides an initial flaw that is required to subsequently produce an unpleasant fracture. Using a variety of laser scoring and / or cutting techniques, it can produce less edge surface damage to the glass substrate, but the cutting process will leave the edge surface even in the case of perfect cutting without any damage to the edge surface. A sharp edge that comes into contact with the major surface of the glass substrate. These sharp edges are easily damaged during the processing of the glass substrate. Therefore, the treatment of the glass substrate to produce a bevel along the edge of the glass substrate can reduce the tendency to damage the glass substrate. Beveling can be performed by grinding and/or polishing the edges of the glass substrate. During the polishing process, water may be applied to the edge surface of the glass substrate, the major surface of the glass substrate, and/or the grinding wheel for beveling the edge to help the particles be washed away from the glass substrate to prevent the glass particles from adhering to the glass substrate. And a contact surface for cooling the glass substrate and the grinding wheel.

When the glass substrate is ground and/or polished, removal of the glass from the edge of the glass substrate produces glass particles that can adhere to the major surface of the glass substrate. If the particles are not removed, the particles can interfere with the downstream process, such as when the display panel is produced, the particles can interfere with film deposition. Thus, the glass substrate can be further processed at the wash station 66, the particles can be washed from the primary surface, and the particles can be washed from the edge surface as needed. The glass substrate can be exposed to one or more detergent solutions and/or cleaning solutions during the washing step. After the glass substrate is cleaned, it can be dried, and can be inspected at the inspection station 68, and then packaged at the packaging station 70 for shipment.

It has been found that in some cases one or both major surfaces of a glass substrate may be contaminated by metal deposits (eg, staining), wherein tiny areas of the glass surface include thin metal deposits, such as but not Limited to iron, calcium, barium, zinc, cobalt, manganese, antimony. Although not well understood for such deposition mechanisms, such deposition mechanisms are believed to occur when the glass is still at significant temperatures (e.g., between about 100 ° C and about 600 ° C), which may occur during the drawing process. Things. Such metal deposition occurs, for example, as glass condensate drops from the pull mechanical structure onto the glass substrate.

Figure 3 shows an image of an exemplary iron deposit at 20X magnification. The particular iron deposit in Figure 3 has a total length of about 460 microns with an annular central region of about 150 microns in length, as well as image streaking in the vertical and horizontal directions. In some processes, metal deposits can be removed by exposing the glass substrate to a relatively strong mineral acid such as hydrofluoric acid (HF) and/or hydrochloric acid. However, the use of these strong acids is expensive, regardless of the cost of the acid itself, the cost of special processing requirements, and the cost of waste disposal of hazardous waste. Again, such acids can cause unnecessary etching of the glass surface.

Accordingly, the inventors have discovered that exposing a glass substrate to a weak acid solution having an acid concentration ranging from about 0.5 ppm to about 1.0 ppm is sufficient to remove sporadic metal deposits, and the weak acid solution is inexpensive and requires no special treatment. And no discernible etch is produced under the conditions described herein. As defined herein, a weak acid comprising an acid dissociation constant K _a is interposed between an acid to the range of 1.8 × 10 ^-16 55.5, or between an acid number of constant ρK _a range between 15.74 to -1.74, wherein ρK _a = -log K _a . Suitable weak acid solutions include hypochlorous acid (K _a = 2.95 x 10 ^-8 , ρK _a = 7.53), boric acid (K _a = 5.8 x 10 ^-10 , ρK _a = 9.24) and phosphoric acid (K _a = 7.5 x 10 ^{- 3} , ρK _a = 2.125) or the above combination, but not limited thereto. Thus, in various embodiments, weak acids having a K _a value ranging from about 2.95 x 10 ^-8 to about 7.5 x 10 ^-3 can be used, including all ranges and subranges therebetween. In a specific embodiment, hypochlorous acid can be used.

According to the specific example shown in FIG. 4, the glass substrate 72 is exposed to a weak acid solution 74, wherein the glass substrate 72 means a glass substrate cut from the mother glass substrate 59, but in a further specific example, the glass substrate may be The mother glass substrate cut by the glass ribbon 58 with or without the removal of the beads. The one or more nozzles 76 are configured to wet one or both major surfaces 78, 80 of the glass substrate, for example, by exposing the weak acid solution from one or more nozzles 76 to expose the glass substrate to a weak acid solution. For example, in various embodiments described herein, the weak acid should completely wet one or both major surfaces 78, 80. In more detail, the surface of the glass treated with hypochlorous acid can be used to remove iron deposits according to the following chemical reactions. Fe + 2HClO → FeCl ₂ + H ₂ +O ₂ (1) 2HClO → 2HCl + O ₂ (2) Fe + 2HCl → FeCl ₂ + H ₂ , (3) where FeCl ₂ is water-soluble and easy to wash downstream Remove it in the step.

Exposure to weak acid can occur at any time after the glass substrate forming process, but in some embodiments, acid exposure is performed during the beveling process at the bevel station 64. However, in various other specific examples, exposure to a weak acid can occur after the beveling process but prior to the washing process at the washing station 66. In some embodiments, as shown in FIG. 5, one or both major surfaces 78, 80 may be exposed by a drizzle 82 (ie, low pressure flow) of acid from one or more nozzles 76. To weak acid. The glass substrate 72 may be disposed at an angle α equal to or greater than 0 degrees and equal to or less than 90 degrees with respect to the horizontal direction, where 0 degrees is a horizontal direction and 90 degrees is a vertical direction. In some embodiments, a weak acid can be applied at a rate ranging from about 7 liters per minute to about 9 liters per minute, such as 8.3 +/- liters per minute. It has been found that at the above concentrations and delivery rates, exposure times between about 20 seconds to about 60 seconds are sufficient to remove metal deposits, for example between about 20 seconds and about 30 seconds, between Between about 20 seconds and about 25 seconds, and including all ranges and subranges between them.

It is apparent that the benefit of the present invention is that the weak acid employed in any of the above specific examples can be deliberately made to specifically remove metal stains from the glass substrate. However, it is apparent that certain weak acids such as hypochlorous acid are available from other sources in the manufacturing facility. For example, hypochlorous acid has been used as an additive due to the ability of hypochlorous acid to inhibit bacterial growth, for example, in cooling water for air conditioning cooling elements such as heat exchangers. In addition, other systems in the manufacturing facility may employ hypochlorous acid-treated water as a hypochlorous acid supply. Hypochlorous acid can be recovered from water recovered by other processes and properly filtered, which can be used as a hypochlorous acid for treating glass substrates as described herein. Therefore, an off-the-shelf supply of a suitable hypochlorous acid solution can be obtained without significant additional cost.

Fig. 6 is a view showing the occurrence of iron deposition on a glass substrate every day for about 6 months in a glass manufacturing apparatus. The period from the left side of the figure to the dashed line 84 in the vertical direction represents the period during which only the alkaline detergent (e.g., Parker 225x) is washed during this period. The vertical axis represents the number of defects (metal stains) detected each day. Line 84 represents the beginning of washing with hypochlorous acid at the beveling station 64. This data shows that once the hypochlorous acid wash is started, the deposited iron is drastically reduced.

It will be apparent from the disclosure of the present invention that treatment with a weak acid solution (e.g., hypochlorous acid) can be performed on any suitable glass article, including glass substrates, glass articles made of glass substrates (e.g., display panels), and any Other glass objects that benefit from the removal of metal stains.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific examples described herein without departing from the spirit and scope of the invention. Therefore, the present invention is intended to cover such modifications and alternatives

10‧‧‧Glass manufacturing equipment / fusion pull-down equipment
12‧‧‧Glass melting furnace
14‧‧‧melting tank
16‧‧‧Upstream glass manufacturing equipment
18‧‧‧ storage container
20‧‧‧Batch conveyor
22‧‧‧Motor
24‧‧‧ batch materials
26‧‧‧ arrow
28‧‧‧Solder glass
30‧‧‧Down glass manufacturing equipment
32‧‧‧First connecting catheter
34‧‧‧Clarification tank
36‧‧‧Mixed tank
38‧‧‧Second connection catheter
40‧‧‧ conveyor
42‧‧‧ molded body
44‧‧‧Export conduit
46‧‧‧ Third connecting conduit
48‧‧‧Molding equipment
50‧‧‧Inlet catheter
52‧‧‧ Groove
54‧‧‧ Converging molding surface
56‧‧‧ root
58‧‧‧glass ribbon
59‧‧‧ glass substrate
60‧‧‧Processing line
62‧‧‧ cutting station
64‧‧‧Chopping platform
66‧‧·Washing station
68‧‧‧Testing platform
70‧‧‧Packing platform
72‧‧‧ glass substrate
74‧‧‧Weak acid solution
76‧‧‧Nozzles
78‧‧‧Main surface
80‧‧‧Main surface
82‧‧‧fine water drops
84‧‧‧ line α‧‧‧ angle

Figure 1 is a schematic illustration of an exemplary glass manufacturing facility.

Figure 2 is a block diagram of a glass substrate processing process downstream of the apparatus of Figure 1.

Figure 3 is a microscopic view of a metal deposit on a glass substrate manufactured by the apparatus of Figure 1.

Fig. 4 is a specific example of a processing apparatus for treating a glass substrate with hypochlorous acid.

Fig. 5 is another specific example of a processing apparatus for treating a glass substrate with hypochlorous acid.

Figure 6 is a graph showing the amount of iron deposits appearing on a glass substrate every day for about 6 months, and showing a significant reduction in iron deposits when the hypochlorous acid wash begins.

Domestic deposit information (please note according to the order of the depository, date, number)

Foreign deposit information (please note in the order of country, organization, date, number)

(Please change the page separately) No

72‧‧‧ glass substrate

74‧‧‧Weak acid solution

76‧‧‧Nozzles

78‧‧‧Main surface

80‧‧‧Main surface

Claims (10)

A method of removing metal deposits from a glass article, the method comprising the steps of: exposing the glass article to an aqueous solution of one of a weak acid having a concentration between 0.5 and 1.0 ppm for a period of time effective to be from one of the glass articles The surface removes a metal deposit. The method of claim 1 request, wherein the weakly acidic solution of one of the dissociation constant K _a line between mid-range of about 2.95 x 10 ^-8 to about 7.5 x 10 ^-3. The method of claim 1, wherein the weak acid is selected from the group consisting of hypochlorous acid, boric acid, and phosphoric acid or a combination thereof. The method of claim 1, wherein the metal deposit comprises at least one of iron, calcium, barium, zinc, cobalt, manganese, cerium, and combinations or alloys thereof. The method of claim 4, wherein the metal deposit comprises iron. The method of any one of claims 1 to 5, wherein the weak acid comprises hypochlorous acid. A method of removing metal deposits from a glass sheet, the method comprising the steps of: exposing the glass sheet to a concentration of 0.5 to 1.0 ppm of an aqueous solution containing hypochlorous acid for a period of time to effectively remove the glass substrate One surface removes metal deposits. The method of claim 7, wherein the metal deposit comprises at least one of iron, calcium, barium, zinc, cobalt, manganese, cerium, and combinations or alloys thereof. The method of claim 7, wherein the glass piece is exposed to hypochlorous acid for a period of time equal to or greater than 20 seconds. The method of any one of claims 7 to 9, wherein the glass sheet is exposed to hypochlorous acid for a period of time ranging from 20 seconds to 60 seconds.