JP6307336B2 - Glass polishing method and glass polishing apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for polishing glass containing Al as a component with a polishing liquid containing hydrofluoric acid.

  In recent years, liquid crystal display devices are widely used in products such as mobile phones, smartphones, tablet PCs, and notebook computers. A liquid crystal display device requires glass that is thick to some extent when the liquid crystal is held between the glasses. However, after encapsulating the liquid crystal between the glasses, the product using the liquid crystal display device can be reduced in weight by making it as light as possible.

  For this reason, the glass filled with liquid crystal is polished and thinned to reduce the weight of the liquid crystal display device. The polishing at this time is performed by etching with an etchant in order to ensure the transparency of the glass.

  In the liquid crystal display device in which the glass part is polished and thinned, there is a problem that the strength of the glass part is reduced. In particular, in a device used around a human head such as a mobile phone or a smartphone, a glass strength of a certain level or more is required. Therefore, the glass for such use is not a soda glass usually used for window glass or the like, but an aluminoborosilicate glass (aluminoborosilicate glass) mixed with boric acid and alumina. That is, in the liquid crystal display device of the product as described above, aluminoborosilicate glass is polished (etched).

  The aluminoborosilicate glass is polished with an etching solution containing hydrofluoric acid (hereinafter also referred to as “polishing solution”). At this time, it is known that unnecessary solids (hereinafter also referred to as “sludge”) that do not contribute to polishing are generated in the polishing liquid.

  In order to polish a large amount of glass, the polishing liquid is often used while circulating. Therefore, if this sludge remains mixed in the polishing liquid, there is a problem that the sludge adheres to the glass surface and the polished glass surface is uneven. Further, during the manufacturing process, when the circulating polishing liquid is filtered, problems such as filter clogging and an increase in filtration time occur.

In order to solve this problem, Patent Document 1 discloses an etching apparatus provided with a sludge treatment unit communicating with an etching tank for performing etching (polishing). The sludge treatment unit includes a precipitation tank and an acid supply unit. In Patent Document 1, sludge is assumed to be a compound (H ₂ SiF ₆ ) in which silicon separated from glass and hydrofluoric acid are combined, and is precipitated once in a precipitation tank. Then, the sludge is dissolved and removed by the acid supplied from the acid supply unit.

Patent Document 2 discloses an invention in which a barium compound is added to an etching solution. Here, the glass to be etched is a silicate glass with a low BaO content, and the glass component contains alumina (Al ₂ O ₃ ).

  In Patent Document 2, in the case of a glass having a low BaO content, a gel-like compound containing fluorine, aluminum, magnesium, and calcium is generated in the etching solution, and the viscosity of the etching solution is increased. It is said that there are problems such as clogging and solidification in piping and tanks. Then, the point by which the production | generation of such a gel-like compound is suppressed by mixing a barium compound in etching liquid is disclosed.

JP 2008-0666706 A JP 2003-313049 A

  In patent document 1, it is going to remove the sludge in the etching liquid used in circulation. However, the cause of sludge generation has not been studied. Therefore, if there are ions that cause sludge to remain in the liquid phase, these ions are circulated as they are. This cannot suppress the generation of sludge on the polished glass surface.

  Also, if the sludge is a compound of an etching solution and a glass component, the particle size of the compound produced by the liquid phase reaction is often fine, and it takes time to remove the sludge by precipitation (decantation). There are challenges. That is, a container for decanting a large amount of etching solution is required, resulting in an increase in equipment size.

  Patent Document 2 clearly shows that the target of etching is aluminoborosilicate glass, and thus the gel-like compound contains fluorine, aluminum, magnesium and calcium. However, it does not attempt to identify and eliminate substances that cause sludge.

  Moreover, an etching rate reduces by adding a barium compound to an etching liquid. Therefore, it can be said that productivity is sacrificed in order to suppress the generation of gel-like foreign matters.

  The present invention has been conceived in view of the above problems, and confirms the cause of sludge generated when aluminoborosilicate glass is polished. Even if the polishing liquid is circulated and used, the sludge remains on the glass surface. It is an object of the present invention to provide a glass polishing method and apparatus that are not generated and that can prevent sludge from solidifying in a production apparatus or piping.

More specifically, the glass polishing method according to the present invention is:
A method for polishing an Al-containing glass with a polishing liquid containing hydrofluoric acid,
A step of solidifying dissolved Al in the polishing liquid after use after polishing the glass to obtain a polishing liquid after reaction;
A step of solid-liquid separation of the polishing liquid after the reaction to obtain a regenerated polishing liquid;
Have a step of polishing the glass in the regeneration polishing liquid,
The step of obtaining the regenerated polishing liquid includes a step of adding a flocculant to the post-reaction polishing liquid and precipitating a solidified product .

Moreover, the glass polishing apparatus according to the present invention comprises:
A reservoir for storing the polishing liquid;
A polishing part that makes Al-containing glass and the polishing liquid contact each other, and returns the used polishing liquid after contact to the storage part,
A reaction vessel to which at least a part of the post-use polishing liquid in the reservoir is transferred;
A metal salt tank that communicates with the reaction vessel and stores a metal salt that removes dissolved Al in the polishing liquid after use;
A solid-liquid separation unit for solid-liquid separation of the post-reaction polishing liquid obtained from the reaction vessel ;
A recycled polishing liquid tank communicated with the solid-liquid separator;
A return pipe that communicates the reclaimed polishing liquid tank and the reservoir ;
Information including the amount of polishing liquid transferred to the reaction vessel, the polishing rate, the Al content in the glass, the polishing amount, and the amount of reclaimed polishing liquid supplied from the reclaimed polishing liquid tank to the reservoir. It has a control part which computes the amount of metal salt thrown into the above-mentioned reaction tank based on .

  As described above, in the glass polishing method of the present invention, specific element ions are added to the post-use polishing liquid used for polishing, and solidified (ions causing sludge) are forcibly solidified and then removed. . Therefore, the regenerated polishing liquid after solid-liquid separation contains almost no ions that cause sludge. That is, the circulating polishing liquid contains almost no ions that cause sludge. Therefore, sludge is hardly generated on the glass surface to be polished. Moreover, accumulation of sludge in the production apparatus and piping is also suppressed.

  In addition, since the specific element added to the polishing liquid after use is used only for forced generation of sludge, the regenerated polishing liquid after solid-liquid separation contains almost no added element. Therefore, the polishing rate of the polishing liquid is not reduced by the operation of removing the sludge.

It is a figure which shows the structure of the conventional glass polishing apparatus. It is a graph which shows Al removal rate of Mg, Ca, Sr, and Ba. Is a chart showing the measurement profile of XRD of sludge is generated by adding MgCl ₂ after the polishing liquid used. It is a graph showing the MgCl ₂ residual amounts of related reactivity polishing solution with added amount of MgCl _2. In addition the amount difference of MgCl _2, is a graph showing the amount of sludge relationship occurs when the amount of the glass component (corresponding to the amount of polishing). It is a figure which shows the structure of the glass polishing apparatus which concerns on this invention. It is a figure which shows the cross section of the liquid crystal display device before and after grinding | polishing. It is a figure which shows the structure of the modification of a grinding | polishing part. It is a figure which shows the structure of the modification of a grinding | polishing part. It is a figure which shows the structure of the glass polishing apparatus which can abbreviate | omit a reaction tank. It is a graph which shows the change of the element component in polishing liquid when not adding Al removal metal salt. It is a graph which shows the change of the sludge density | concentration in polishing liquid. It is a graph which shows the relationship between the change of the component density | concentration in polishing liquid, and product quality. It is a graph which shows the change of the element component in polishing liquid at the time of throwing in Al removal metal salt. It is a graph which shows the relationship between the change of sludge density | concentration, and product quality. It is a figure which shows the structure which added the solid-liquid separation part to the glass polishing apparatus of FIG.

  The glass polishing method and polishing apparatus according to the present invention will be described below. The following description shows one embodiment of the present invention, and the following embodiment and examples may be modified without departing from the spirit of the present invention.

(Embodiment 1)
The glass polishing method and apparatus of the present invention is aluminoborosilicate glass. More specifically, it is a strength glass mainly composed of SiO _{2 and} containing Al ₂ O ₃ , B ₂ O ₃ , BaO, CaO, MgO, Na ₂ O, and SrO and having a high tensile strength and a high softening point. It can be said that the glass contains aluminum. Hereinafter also referred to as “Al-containing glass”. The polishing liquid mainly contains hydrofluoric acid and inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid. In addition, additives such as surfactants, antifoaming agents, chelating agents may be included.

  Sludge generated when aluminoborosilicate glass is polished is a substance precipitated from the polishing liquid among the complex in which elements in aluminoborosilicate glass and fluorine derived from hydrofluoric acid in the polishing liquid are combined. It is. The inventor of the present application is that sludge generated when aluminoborosilicate glass is polished is a compound of Sr, Al, and F (Sr—Al—F precipitate), a compound of Ca, Al, and F (Ca—Al -F precipitate), a compound of Mg, Al and F (Mg-Al-F precipitate) and a compound of Ba, Al and F (Ba-Al-F precipitate).

  And, during the circulation of the polishing liquid, by removing Al-F complex ions that are the cause of generation of these compounds from the polishing liquid after use, sludge is generated on the surface of the glass that is the object to be polished and each part of the polishing apparatus As a result, the present invention has been conceived. The principle of the present invention will be described below while showing the flow of examination. Then, the structure of the glass polishing method and glass polishing apparatus according to the present invention will be described.

<Confirmation of sludge composition>
The component of the sludge was confirmed by polishing with a polishing liquid in which aluminoborosilicate glass was circulated and analyzing the sludge deposited in the polishing liquid. FIG. 1 shows the configuration of an aluminoborosilicate glass polishing apparatus. This may be called a conventional glass polishing apparatus. The polishing apparatus 100 includes a transfer unit 124 that transfers glass, a storage unit 112 that stores a polishing liquid, and a shower unit 114 that sucks the polishing liquid from the storage unit 112, sprays the polishing liquid onto the glass, and performs polishing.

  The shower unit 114 includes a pipe 114b for feeding a polishing liquid from the storage unit 112 to the transfer unit 124, and a pump 114p. The nozzle 116 of the shower unit 114 is provided above the storage unit 112, and the polishing liquid sprayed on the glass falls into the storage unit 112 as it is. By comprising in this way, polishing liquid is used cyclically.

  By polishing the glass, sludge is generated in the polishing liquid in the reservoir 112. The sludge is filtered by the filter 114f, and most of the sludge is removed from the polishing liquid. The sludge collected by this filter 114f exhibited a white powder when dried. The composition of the powdery sludge was quantitatively measured by ICP emission analysis and ion chromatography.

  As a result, in terms of mass%, F (fluorine) and Sr (strontium) account for 60 mass% or more, Al (aluminum) is about 13 mass%, Ca (calcium) and Mg (magnesium) are about 6 mass%, respectively. there were. On the other hand, compared with the composition of aluminoborosilicate glass, Ba (barium) and Si (silicon) were very small amounts, and B (boron) and Na (sodium) were not detected at all.

Usually, fluoride (AlF ₃ , SrF ₂ , CaF ₂ , MgF _2, etc.) is suspected as a component of sludge, but the polishing liquid contains inorganic acid in addition to hydrofluoric acid, and is extremely acidic. (= Low pH) Therefore, it is considered that HF, H ₂ F ₂ , and HF ₂ ⁻ are mainly present in hydrofluoric acid other than the following complex. That is, it can be concluded that precipitation of fluoride is unlikely to occur because the amount of F ⁻ which is the cause of fluoride formation is an extremely low environment.

Although Si is the main component of aluminoborosilicate glass, it was hardly found in the sludge. Also, B, which is one of the main additives of aluminoborosilicate glass, was not detected in the sludge. From these facts, Si and B are considered to exist in the liquid phase in the polishing liquid as Si-F complexes (silica fluoride ions, SiF ₆ ²⁻ ) and BF complexes (borofluoride ions, BF ₄ ⁻ ). It was. Al is known to exist in the liquid phase as an Al—F complex (fluoroaluminate ion, AlF ₆ ³⁻ , AlF ₅ ²⁻ , AlF ₄ ^−, etc.).

  However, a high concentration of Al component was detected in the sludge. From this, it is concluded that the sludge is solidified by combining the Al—F complex with a divalent element such as Sr, Ca, Mg, and Ba. Although a trace amount of Ba was detected in the sludge, the composition ratio in the aluminoborosilicate glass was originally very small, so it can be said that almost the entire amount was solidified.

  Sludge is generated by combining Sr, Ca, Mg, Ba and Al—F complex ions. Therefore, as long as Al-F complex ions are present in the polishing liquid, sludge is generated even on the surface of the glass to be polished. This is because they react with these elements in the aluminoborosilicate glass. That is, it is not possible to suppress the generation of sludge in the polishing apparatus or piping simply by removing the generated sludge. Moreover, the generation of sludge on the surface of the glass to be polished cannot be suppressed. Therefore, in the polishing of aluminoborosilicate glass, Al—F complex ions themselves must be removed from the polishing liquid in order to suppress sludge generated on the glass surface.

  Sludge is generated by combining Al-F complex ions and divalent elements such as Sr, Ca, Mg, and Ba. Therefore, the inventor of the present invention actively adds divalent metal ions to the polishing liquid after being used for polishing (hereinafter referred to as “post-use polishing liquid”) to generate sludge and remove the sludge. I thought that these elements could be removed. If this method is introduced outside the polishing apparatus, the sludge generation location can be removed from the conventional polishing apparatus to the outside of the polishing apparatus, and as a result, the sludge concentration in the polishing apparatus can be greatly reduced. Is possible.

  That is, the point of the present invention is to remove Al—F complex ions themselves in the polishing liquid by positively generating sludge in the polishing liquid after use and removing the generated sludge. Here, “removal” includes solidifying and separating the Al—F complex ions.

It was confirmed as follows that sludge can be generated positively in the polishing liquid after use. MgCl ₂ aqueous solution, CaCl ₂ aqueous solution, SrCl ₂ aqueous solution, and BaCl ₂ aqueous solution were added to the post-use polishing liquid obtained by the polishing apparatus 100 shown in FIG. 1 while changing the concentration. And stirring reaction was performed for 1 hour in the temperature state of 23 degreeC. The post-reaction polishing liquid is called post-reaction polishing liquid. After the reaction, the resulting polishing liquid is centrifuged to separate solids (sludge), and the Al concentration in the supernatant is analyzed by ICP emission spectroscopy (Inductively Coupled Plasma).
(Atomic Emission Spectrometry: hereinafter referred to as “ICP-AES”).

  And Al removal rate was calculated | required by making Al concentration when not adding each aqueous solution into 100% on a molar basis. The results are shown in FIG. In addition, it can be said that the removal rate of Al is what removed the Al-F complex ion. A polishing liquid obtained by removing sludge from the polishing liquid after the reaction is called a regenerated polishing liquid.

Referring to FIG. 2, the horizontal axis represents the divalent element addition concentration (mmol-Metal / L), and the vertical axis represents the Al removal rate (mol%). It was found that any divalent element of Mg, Ca, Sr, and Ba can remove Al in the polishing liquid after use. Moreover, it turned out that the removal rate of Mg is the highest among these four elements. That is, most sludge can be generated when MgCl ₂ is added to the polishing liquid after use.

After use, sludge produced by adding MgCl ₂ to the polishing liquid was centrifuged and washed with distilled water, dried at 23 ° C., and examined by XRD (X-Ray Diffraction). MgAlF ₅ · 1.5˜ 2H ₂ O. An XRD profile is shown in FIG. Referring to FIG. 3, the horizontal axis is 2θ (°), and the vertical axis is the count number.

  Further, when other elements were similarly examined by XRD, it was found to be a compound with Al and F. Therefore, the sludge is composed of a compound of Sr, Al, and F (Sr—Al—F precipitate), a compound of Ca, Al, and F (Ca—Al—F precipitate), and a compound of Mg, Al, and F. (Mg—Al—F precipitate) and a compound of Ba, Al, and F (Ba—Al—F precipitate) were confirmed.

<Polishing liquid with sludge removed>
Next, sludge was forcibly generated in the polishing liquid after use, and the amount of sludge generated when the polishing liquid (regenerated polishing liquid) from which the Al—F complex ions had been removed was used for polishing was verified. After use, an aqueous MgCl ₂ solution was added to a polishing liquid (aluminoborosilicate glass dissolved at about 180 g / L), and the mixture was reacted by stirring at 23 ° C. for 1 hour to obtain a polishing liquid after reaction. After the reaction, the polishing liquid was centrifuged, and the Al concentration of the supernatant liquid (regenerated polishing liquid) was measured by ICP-AES. Next, 50 mL of the regenerated polishing liquid was impregnated with aluminoborosilicate glass (2.5 cm × 5 cm) and polished under conditions of 40 ° C. for 10 minutes.

  The weight of the glass after polishing was measured, and the solubility of the glass was measured. And the used polishing liquid used for grinding | polishing was filtered with a 1 micrometer filter (PTFE: polytetrafluoroethylene), the sludge was capture | acquired, and the sludge generation amount was measured.

The results are shown in Table 1. Referring to Table 1, the first line shows two categories of Al removal treatment process and glass polishing process. In the Al removal treatment step, the treatment conditions indicate the amount of MgCl ₂ (mg-Mg / L) added to the polishing liquid after use and the reaction temperature. The composition of the treatment liquid is obtained by measuring the amount of Al in the regenerated polishing liquid, the amount of added Mg, and the total fluorine quantity in the polishing liquid.

  On the other hand, in the glass polishing step, the polishing conditions indicate the amount of glass polished (glass polishing amount) and the polishing temperature (° C.) by polishing at 40 ° C. for 10 minutes using a regenerated polishing liquid. The sludge generation amount is the total weight (g) of the generated sludge and the sludge weight converted to the unit weight of the glass.

Referring to the Al removal treatment step in Table 1, it was found that when MgCl ₂ was increased, the remaining amount of Al decreased accordingly (see “Al and Mg” in “Composition of treatment liquid”). On the other hand, when MgCl ₂ is added, the amount of sludge generated (see the glass polishing step) is once reduced (total weight 0.09 g) from the state where it is not added (total weight 0.291 g). However, the amount of sludge then increases (total weight 0.133 g, 0.225 g, 0.388 g). In other words, it was found that Al—F complex ions can be removed by increasing MgCl ₂ , but excessive addition promotes the generation of sludge.

This was considered to be because Mg ions became excessive from the remaining Al—F complex ions. In order to confirm this, an experiment was performed according to the following procedure. After use, MgCl ₂ was added to the polishing liquid, and a stirring reaction was performed at 40 ° C. for 1 hour. Next, the reaction liquid (this is called “post-reaction polishing liquid”) was centrifuged, and the Mg ion concentration in the supernatant liquid (regenerated polishing liquid) was measured. The result is shown in FIG. In FIG. 4, the horizontal axis represents the MgCl ₂ addition amount (mol-Mg / mol-Al), and the vertical axis represents the Mg residual concentration (mg / L) in the regenerated polishing liquid.

Referring to FIG. 4, when the added amount of MgCl ₂ increases and becomes equal to or higher than the molar concentration and molar equivalent of Al in the used polishing liquid (on the right side of the paper from 1.0 indicated by the dotted line on the horizontal axis), the regenerated polishing liquid It was found that the residual Mg residual concentration increased linearly. That is, in order to remove the Al—F complex ions, Mg ions equivalent to the Al concentration in the polishing liquid after use must be added. This is because the presence of Mg ions in excess of the Al—F complex ions increases sludge generation.

The effect of preventing the Mg ions in the regenerated polishing liquid from remaining was confirmed. After use, those having different concentrations of MgCl ₂ aqueous solution are added to the polishing liquid, and the mixture is stirred at 40 ° C. for 1 hour. The Al concentration, Mg concentration, and fluorine concentration of the filtrate (regenerated polishing liquid) obtained by centrifuging the solution after the reaction were measured.

  Each of these regenerated polishing liquids is composed of glass, 55 g, 117 g, and 190 g of glass components (Sr, Ca, Mg, Ba corresponding to the composition ratio of the aluminoborosilicate glass with respect to 1 L of the polishing liquid, all chlorides. Was prepared and allowed to stand at 40 ° C. for 1 hour. This is an experiment simulating polishing aluminoborosilicate glass with a regenerated polishing liquid with different amounts of remaining Al.

Since sludge was generated in the regenerated polishing liquid charged with the glass component, it was collected with a 1 μm filter (PTFE), and the amount of sludge generated was measured. The results are shown in Table 2. In Table 2, it divided roughly into two, the Al removal treatment process and the glass component addition process. In the Al removal treatment step, the treatment conditions indicate the amount of MgCl ₂ (mg-Mg / L) added to the polishing liquid after use and the reaction temperature. The composition of the treatment liquid is a value obtained by measuring the Al amount and Mg amount in the regenerated polishing liquid obtained by adding MgCl ₂ to the polishing liquid after use, and the total fluorine amount in the polishing liquid.

  On the other hand, in the glass component addition step, the sludge generation amount (mg / L) is a glass component equivalent to 55 (g-Glass / L), 117 (g-Glass / L), 190 (g-Glass / L). This is the amount of sludge generated that can be introduced and obtained.

Looking at the Al removal treatment step, the concentration of Al in the regenerated polishing liquid in the column of the composition of the treatment liquid decreases as the additive concentration of Mg in the column of the treatment condition increases. On the other hand, the Mg concentration in the treatment liquid column has almost no change, and increases to 40 (mg / L) when the amount of MgCl ₂ added in the treatment condition column is 2441 (mg-Mg / L). This is considered that the MgCl ₂ addition amount on the horizontal axis in FIG.

  Next, look at the column of the glass component addition step. Here, when the table is viewed in the horizontal direction, the amount of glass component added increases. For example, the top row with numerical values describes the amount of sludge generated when glass components equivalent to 55 g, 117 g, and 190 g are added to the reclaimed polishing liquid in which the amount of Mg added is 0 (zero) in the Al removal treatment process. Has been. Similarly, in the row immediately below the re-up row where the numerical values are described, 55 g, 117 g, and 190 g of glass components corresponding to the regenerated polishing liquid when the Mg addition amount was 412 (mg-Mg / L) were added. The amount of sludge generated at the time is described.

  Compared to the case where the amount of Mg added is zero, 412 (mg-Mg / L) of Mg is added and sludge is forcibly generated and removed, so that the Al-F complex in the regenerated polishing liquid is removed. Ion concentration is decreasing. Therefore, the amount of sludge generated is smaller than when the amount of Mg added is zero. FIG. 5 shows the relationship between the sludge generation amount (concentration) generated in the regenerated polishing liquid and the added glass component addition amount for each addition amount of Mg in Table 2.

Referring to FIG. 5, the horizontal axis represents the glass component addition amount (g-Glass / L), and the vertical axis represents the sludge generation concentration (mg / L). A plurality of broken lines indicate that MgCl ₂ addition amount is 0 (none): A, 412 (mg-Mg / L): B, 948 (mg-Mg / L): C, 1724 (mg-Mg / L): D , 2441 (mg-Mg / L): E is shown.

Apparently, the amount of sludge generated decreases as the amount of MgCl ₂ added increases ("Line A" to "Line E" in FIG. 5). The sludge volume is not a region increases as the added amount of MgCl ₂ is increased. This is because the amount of MgCl ₂ is controlled in the state where the added amount of MgCl ₂ is around 1.0 in FIG. That is, by adding MgCl ₂ having a molar equivalent or less than the Al concentration in the polishing liquid after use, excess Mg does not remain in the regenerated polishing liquid. Therefore, the generation of sludge is suppressed.

Now, the regenerated polishing liquid from which Al—F complex ions have been removed is a polishing liquid in which sludge is hardly generated. However, it is necessary to confirm whether or not the polishing liquid treated in this way can withstand actual use. Therefore, the following experiment was conducted. After use, an aqueous MgCl ₂ solution is added to the polishing liquid, and a stirring reaction is performed at 40 ° C. for 1 hour. The Al concentration of the filtrate (regenerated polishing liquid) obtained by centrifugation was measured. Then, 50 mL of the regenerated polishing liquid was impregnated with glass (2.5 × 5 cm), and the polishing rate was measured. In addition, instead of MgCl _2, an ultrapure water (control) was also prepared. The results are shown in Table 3.

As the added amount of MgCl ₂ increases (see “Mg concentration” column), the Al concentration in the regenerated polishing liquid decreases (see “Al” column). On the other hand, the polishing rate also decreased according to the amount of MgCl ₂ aqueous solution added. However, the polishing rate was also lowered in the case of adding ultrapure water. That is, it was determined that the decrease in the polishing rate was not caused by the addition of MgCl ₂ but the polishing liquid itself was diluted.

  Moreover, even when the Al concentration in the regenerated polishing liquid was reduced to 15 mg / L, the polishing rate was 13.80 μm / min or more. In general, for use in mass production, it is said that 12 μm / min or more is a standard, so it can be said that the polishing rate can be sufficiently used even in mass production.

From the above experiments, it was confirmed that the polishing liquid in which sludge was forcibly generated by adding MgCl ₂ and the Al—F complex ions were reduced can be sufficiently used as the polishing liquid again.

<Flocculant>
By removing the sludge from the polishing liquid in which the Al—F complex ions are reduced, a regenerated polishing liquid can be obtained. However, the sludge in the polishing liquid after reaction is often fine particles. Therefore, if this is removed only by the filter, the filter is clogged in a short time. If the fine sludge can be agglomerated into a large lump, the filter replacement time can be extended. It is also possible to precipitate in a short time. If solid-liquid separation can be achieved by precipitation, the load on the filter will be light and economical. Then, it confirmed about the effect of the flocculant of the sludge in polishing liquid after reaction as follows.

First, an MgCl ₂ aqueous solution was added to the polishing liquid after use in an amount equivalent to the equivalent of Al-F complex ions, and the mixture was kept at 40 ° C. for 1 hour with stirring reaction. After this reaction, sludge was generated in the polishing liquid as before. In this polishing solution after reaction, a sodium polyacrylate polymer (Akofloc A-190 manufactured by MT Aquapolymer Co., Ltd.) as an anionic flocculant, and polyacrylamide (Acofloc N manufactured by MT Aquapolymer Co., Ltd.) as a nonionic flocculant. -100S), a polyacrylate polymer (Aron Flock C-508 manufactured by MT Aquapolymer Co., Ltd.) was added as a cationic flocculant to a concentration of 5 ppm, and the mixture was stirred for 1 minute and allowed to stand. .

  When visually observed after 10 minutes, there was no significant change between the anionic flocculant and the cationic flocculant. However, with polyacrylamide, which is a nonionic flocculant, sludge was precipitated and a clear supernatant was obtained. From this, it was found that if a nonionic flocculant is added to the abrasive after the reaction, a large amount of sludge can be removed by precipitation during solid-liquid separation.

<Glass polisher>
Based on the above examination, the structure of the glass polishing apparatus according to the present invention is shown in FIG. The glass polishing apparatus 1 of the present invention includes a polishing tank 10 having a transfer means 24 for transferring an object to be polished 90, a polishing part 13 for polishing the object 90 to be polished, a storage part 12 for storing a polishing liquid, and Al- An F complex removing device 21, a solid-liquid separation unit 25, and a regenerated polishing liquid tank 32 are included. Moreover, you may have the new liquid supply part 35. FIG.

  The structure of the workpiece 90 is shown in FIG. The object to be polished 90 is a liquid crystal display device in which a liquid crystal 94 is sandwiched between two glass portions 91a and 91b containing aluminum such as aluminoborosilicate glass. Moreover, it is not limited to a liquid crystal display device, The aluminum containing glass should just be used for at least 1 surface.

  The end of the object to be polished 90 is liquid-tightly sealed with a shield 93. FIG. 7B shows a state where the glass portions 91a and 91b of the workpiece 90 are polished. The glass portions 91a and 91b are thinned by polishing. Thus, by thinning the glass portions 91a and 91b, the weight of the workpiece 90 is reduced.

  Referring again to FIG. 6, the workpiece 90 passes through the polishing tank 10 by the transfer means 24. The transfer means 24 is not particularly limited as long as the workpiece 90 can be transferred. A roller conveyor that supports the edge of the workpiece 90, a chain conveyor having a hook that suspends the workpiece 90, and the like are preferably used. In particular, it is preferable if it can be transferred in a state where both surfaces of the glass portion of the workpiece 90 are exposed. This is because both surfaces can be polished at a time by spraying the polishing liquid from both sides.

  The polishing tank 10 is a box-shaped container formed of a material having corrosion resistance, and is provided with an inlet 10 i and an outlet 10 o for the transfer means 24. It is desirable that the polishing tank 10 be sealed as much as possible. This is because a highly corrosive solution such as hydrofluoric acid is used as the polishing liquid.

  In the polishing tank 10, a storage unit 12 for storing the polishing liquid and a shower unit 14 for injecting the polishing liquid onto the workpiece 90 are provided. The shower unit 14 draws up the polishing liquid in the storage unit 12 and injects it onto the workpiece 90. Therefore, the shower unit 14 includes a pipe 14b having a suction port 14bi at the bottom of the storage unit 12, a polishing liquid pump 14p communicating with the pipe 14b, a pipe 14a connected to the liquid supply port of the polishing liquid pump 14p, and a pipe. The branch pipes 14aa and 14ab branched from the pipe 14a and the nozzles 16a and 16b provided in the branch pipes 14aa and 14ab are included.

  At least the suction port 14bi, the branch pipes 14aa and 14ab, and the nozzles 16a and 16b are provided inside the polishing tank 10. By injecting the polishing liquid onto the object 90, the object 90 is polished and the thickness of the Al-containing glass is reduced. That is, it can be said that the shower unit 14 is the polishing unit 13.

  The storage unit 12 is a container that receives a polishing liquid (post-use polishing liquid) that drops after being sprayed from the nozzles 16 a and 16 b of the shower unit 14 onto the object to be polished 90. Since it receives the falling polishing liquid after use, it has an opening above and is disposed below the shower 14. In general, polishing is often performed using a heated polishing liquid, and a heating device is installed in the storage unit 12 to be adjusted to a predetermined temperature.

  The storage unit 12 is provided with a drain pipe 18 having a drain port 18a in addition to the suction port 14bi. A valve 18b is disposed in the drain pipe 18. An Al—F complex removal device 21 is connected to the drain pipe 18. The Al—F complex removing device 21 adds a salt having at least one element of Mg, Ca, Sr, and Ba to the Al—F complex in the post-use polishing liquid accumulated in the reservoir 12 to forcibly make sludge. Is a device that removes the Al—F complex from the polishing liquid after use.

  The Al—F complex removal apparatus 21 includes a reaction tank 20 and an Al removal metal salt addition unit 22. The Al removal metal salt addition unit 22 includes a metal salt tank 22a, a pipe 22b communicating with the reaction tank 20, and a valve 22c provided in the middle of the pipe 22b.

  The drain pipe 18 is in communication with the reaction tank 20 of the Al—F complex removal device 21. The reaction tank 20 also communicates with a pipe 22b from the metal salt tank 22a. Further, the reaction vessel 20 is provided with a stirrer 20a. Further, the reaction vessel 20 may be provided with a temperature adjusting means 20c.

  The temperature adjusting means 20c includes a water jacket provided around the reaction tank 20, a heater and a temperature adjusting device provided in a water jacket (not shown). That is, the entire reaction vessel 20 is maintained at a predetermined temperature with the water jacket. A polishing liquid containing a large amount of highly corrosive hydrofluoric acid is injected into the reaction tank 20. Therefore, it is difficult to install a thermometer.

  A solid-liquid separation unit 25 is provided downstream of the Al—F complex removal device 21. The solid-liquid separation unit 25 may be simply the filter 28. However, it is preferable to use the flocculant addition unit 26 and the filter 28 because the filter 28 is less likely to be clogged.

  The flocculant addition unit 26 includes a flocculant tank 26d communicating with the liquid feed pipe 20b from the reaction tank 20, a flocculant tank 26a, a liquid feed pipe 26b communicating with the flocculant tank 26a and the flocculant tank 26d, and a liquid feed pipe. It includes a valve 26c provided in 26b. The aggregation tank 26d may be provided with a stirrer 26m. Further, the coagulant adding unit 26 may be provided with a precipitation tank 27. An example of the sedimentation tank 27 is a container or tank provided with a partition 27a penetrating at the bottom.

  A liquid feeding pipe 26e from the aggregation tank 26d is communicated with one section, and a liquid feeding pipe 27b in the downstream direction is communicated with the other section. The supernatant from which the sludge has naturally settled in the settling tank 27 communicates with the filter 28 via the liquid feeding pipe 27b in the downstream direction. The filter 28 is a filter press, a bag filter, or the like, and the filter medium is made of a highly corrosion-resistant material such as PTFE or PP.

  In addition, the filter 28 may be disposed directly downstream of the Al—F complex removal device 21. That is, the solid-liquid separation unit 25 may be configured by the filter 28 alone. In this case, the downstream liquid feeding pipe 20 b of the reaction tank 20 of the Al—F complex removing device 21 communicates directly with the filter 28.

  A regenerated polishing liquid tank 32 is provided downstream of the filter 28 through the liquid supply pipe 28a. The regenerated polishing liquid tank 32 is a tank for storing a polishing liquid (regenerated polishing liquid) from which the Al—F complex has been removed. A return pipe 32 a is connected from the regenerated polishing liquid tank 32 to the reservoir 12. A circulation pump 34 is provided in the return pipe 32a.

  The storage unit 12 is provided with a new liquid supply unit 35 for supplying a new liquid hydrofluoric acid solution. The new liquid supply unit 35 may include a hydrofluoric acid supply unit 36 and an inorganic acid supply unit 38 separately. The hydrofluoric acid supply unit 36 supplies hydrofluoric acid to the polishing liquid. A hydrofluoric acid tank 36a, a pipe 36b, and a valve 36c are included. The inorganic acid supply unit 38 supplies an acidic inorganic acid such as hydrochloric acid, nitric acid, and sulfuric acid to the polishing liquid. In addition, even if it supplies hydrofluoric acid or an inorganic acid separately, or it supplies only one, it may be said that a new liquid is supplied.

  The glass polishing apparatus 1 may be provided with a control unit 50. The controller 50 is provided for controlling the operation of the glass polishing apparatus 1. The controller 50 controls the opening and closing of the polishing liquid pump 14p, the circulation pump 34, and various valves. Further, it is possible to calculate the amount of the Al—F complex in the used polishing liquid in the reservoir 12 from the number of processed objects 90 to be processed, the amount of the polishing liquid ejected from the nozzles 16a and 16b, and the like. desirable.

  Since the polishing liquid is a highly corrosive solution, it is often very difficult to directly measure the Al—F complex in the polishing liquid after use. Therefore, it is preferable to calculate the concentration of the Al—F complex in the polishing liquid after use based on the polishing rate examined in advance.

  In FIG. 6, the control unit 50 represents a signal transmission line for a pump, a valve, and the like to be controlled by a one-dot chain line, and represents an input of data such as the number of processed sheets by a two-dot chain line. For the number of processed sheets, the number of sheets actually processed may be counted, or the transfer time or transfer distance of the transfer means 24 may be referred to.

  The operation of the glass polishing apparatus 1 having the above configuration will be described. Initially, the polishing liquid (new liquid) is injected into the reservoir 12. When the glass polishing apparatus 1 starts operation, the object to be polished 90 is transferred into the polishing tank 10 by the transfer means 24. The polishing liquid is sprayed from the nozzles 16a and 16b to the workpiece 90 transferred to the polishing tank 10. The sprayed polishing liquid hits the glass portions 91a and 91b of the workpiece 90 and polishes (etches) the glass portions 91a and 91b.

  Polishing liquid which grind | polished the glass part falls in the storage part 12 as it is. The glass component is dissolved in the polishing liquid obtained by polishing the glass portion. The polishing liquid in which the glass component is dissolved is a polishing liquid after use. As described above, the post-use polishing liquid contains Al-F complex ions and each component element of glass.

  The used polishing liquid that has fallen into the reservoir 12 flows through the pipe 14b from the suction port 14bi and is pressurized by the polishing liquid pump 14p. Thereafter, it flows through the pipe 14a, passes through the branch pipes 14aa and 14ab, and is again sprayed from the nozzles 16a and 16b onto the workpiece 90. Thus, the used polishing liquid is circulated and used. Note that the polishing liquid in the reservoir 12 may be referred to as a post-use polishing liquid after the post-use polishing liquid is mixed.

  The amount of Al—F complex ions increases while the polishing liquid after use is circulated and used. As already mentioned, the presence of Al-F complex ions causes sludge formation. Therefore, after polishing a certain number of objects to be polished 90, the valve 18b is opened, and the used polishing liquid in the storage section 12 is passed through the drain pipe 18 from the drain port 18a in the storage section 12 through the Al-F complex removal device 21. To the reaction tank 20. On the other hand, the regenerated polishing liquid in the regenerated polishing liquid tank 32 may be injected into the storage unit 12 by the circulation pump 34. Moreover, a new liquid may be supplied.

A predetermined amount of the metal salt aqueous solution is added from the Al removal metal salt addition unit 22 to the post-use polishing liquid sent to the reaction tank 20. The metal salt to be used is a salt of at least one element selected from Mg, Ca, Sr, and Ba, and chloride, nitrate, sulfate, and the like can be used. In particular, a salt of an inorganic acid contained in the polishing liquid is desirable. For example, when the inorganic acid contained in the polishing liquid is hydrochloric acid, it is chloride (MgCl ₂ ), when it is sulfuric acid, it is sulfide (MgSO ₄ ), and when it is nitric acid, it is nitrate (Mg (NO ₃ ) ₂ ). . This is because the use of the same salt as the inorganic acid contained in the polishing liquid reduces the influence on polishing. Further, when a plurality of inorganic acids are contained in the polishing liquid, a salt of the same inorganic acid may be used. That is, the metal salt aqueous solution may contain a plurality of salts with inorganic acids.

  The amount of the metal salt aqueous solution added to the reaction vessel 20 can be calculated if the Al—F complex ion concentration in the post-use polishing liquid introduced into the reaction vessel 20 is known. The control unit 50 calculates the amount of the metal salt aqueous solution, controls the Al removal metal salt addition unit 22, and adds an appropriate amount of the metal salt aqueous solution to the reaction vessel 20.

  The calculation of the Al—F complex ion concentration in the polishing liquid after use may be appropriately determined according to the operation method of the glass polishing apparatus 1 and the Al—F complex removal apparatus 21. Basically, it is based on the following principle. The Al—F complex concentration in the post-use polishing liquid is the polishing liquid concentration in the reservoir 12. Therefore, it is only necessary to be able to calculate the Al—F complex concentration of the post-use polishing liquid in the reservoir 12 at the time of introduction into the Al—F complex removing device 21.

  The Al-F complex concentration of the used polishing liquid in the reservoir 12 is determined by the polishing rate determined by the composition of the polishing liquid used and the object 90 to be polished, the Al composition ratio of the object 90 to be polished, and the processing of the object 90 to be polished. From the number of sheets, the new amount of polishing liquid supplied by the new liquid supply unit 35 (hydrofluoric acid supply unit 36 and inorganic acid supply unit 38), and the amount of regenerated polishing liquid supplied from the regenerated polishing liquid tank 32 Can be calculated.

  Therefore, the control unit 50 determines the amount of polishing liquid transferred to the reaction tank 20, the polishing rate, the Al content of the workpiece 90 (glass), the number of processed sheets (polishing amount), and the supply amount of the regenerated polishing liquid. It can be said that the amount of metal salt solution (the amount of metal salt) charged into the reaction vessel 20 is calculated based on the above. In addition, when a new liquid is introduced, the new liquid supply amount may be added as a parameter. The number of processed sheets (polishing amount) may be a cumulative number of polished sheets. The calculation of the Al—F complex concentration may be referred to as a step of calculating the Al concentration.

  The Al removal metal salt addition unit 22 adds a metal salt having an equimolar amount or less of Al from the calculated Al—F complex ion concentration to the reaction tank 20 from the metal salt tank 22a through the pipe 22b. This may be performed by the controller 50 controlling the valve 22c, or by controlling a pump (not shown). Thereafter, the reaction vessel 20 is reacted while being stirred by the stirrer 20a. The reaction time is about 10 minutes.

  By this reaction, most of the Al—F complex ions in the polishing liquid after use become sludge. Further, the metal ions added as the metal salt hardly remain in the polishing liquid. Thus, the Al-F complex ions in the polishing liquid after use react with the divalent metal ions to forcibly generate sludge when the dissolved Al in the polishing liquid after use is solidified, separated or removed. You can say that. The polishing liquid from which dissolved Al is separated is a post-reaction polishing liquid.

  The post-reaction polishing liquid is divided into the polishing liquid from which the sludge and Al—F complex ions have been removed by the solid-liquid separation unit 25. The polishing liquid from which the Al—F complex ions have been removed is called a regenerated polishing liquid. The solid-liquid separation unit 25 may include a flocculant addition unit 26 and a filter 28. Moreover, you may comprise only with the filter 28. FIG. It is preferable to provide the flocculant addition unit 26 because the load on the filter 28 is small and clogging is difficult to occur. In FIG. 6, the case where the flocculant addition part 26 is provided is shown.

  The post-reaction polishing liquid is added with a flocculant at the flocculant addition section 26. The post-reaction polishing liquid is fed from the reaction tank 20 to the aggregation tank 26d through the liquid feeding pipe 20b. Then, the flocculant is added from the flocculant tank 26a to the aggregating tank 26d through the liquid feeding pipe 26b. When a flocculant is added and stirred with a stirrer 26m, sludge aggregates in the polishing liquid after reaction in a short time of about 10 minutes. As already indicated, the flocculant used here is a nonionic resin, and polyacrylamide can be suitably used. The post-reaction polishing liquid in which the sludge in the aggregation tank 26d has aggregated is sent to the sedimentation tank 27 via the liquid feeding pipe 26e, and the sludge aggregates are settled and separated.

  Then, only the supernatant of the sedimentation tank 27 is sent to the filter 28 via the liquid feeding pipe 27b. The filter 28 further separates fine sludge. The precipitation by the flocculant addition unit 26 and / or the removal of sludge by the filter 28 is called solid-liquid separation. In other words, removing sludge in the solid-liquid separation unit 25 is called solid-liquid separation. The post-reaction polishing liquid after the solid-liquid separation is finished is a regenerated polishing liquid. The regenerated polishing liquid is sent to the regenerated polishing liquid tank 32 through the liquid supply pipe 28a and stored.

  Thereafter, when the post-use polishing liquid in the storage unit 12 is sent to the Al-F complex removal device 21, the regenerated polishing liquid in the regenerated polishing liquid tank 32 is transferred to the storage unit 12 via the return pipe 32a. The liquid is sent. That is, the used polishing liquid and the regenerated polishing liquid in the storage unit 12 are exchanged. The regenerated polishing liquid is used to polish the glass at the shower unit 14. That is, the polishing liquid is recycled.

  It is a desirable method to replace all of the used polishing liquid in the reservoir 12 with the regenerated polishing liquid. However, if all of the post-use polishing liquid in the reservoir 12 is to be replaced, the polishing must be interrupted once. On the other hand, when the regenerated polishing liquid is added while leaving a part of the used polishing liquid in the reservoir 12, the Al—F complex ion concentration in the used polishing liquid of the reservoir 12 dynamically changes. Therefore, the calculation of the concentration of Al—F complex ions in the polishing liquid of the reservoir 12 must be calculated by a differential equation.

  However, since the polishing liquid remains in the reservoir 12, the polishing itself can be continued without stopping. This can be a great advantage in an actual production device. Therefore, the amount of the used polishing liquid sent from the storage unit 12 to the Al—F complex removal device 21 may be at least a part of the storage unit 12.

  Note that the new liquid may be periodically supplied from the new liquid supply unit 35 to the polishing liquid containing the post-use polishing liquid of the storage unit 12. As for the supply of the new liquid, hydrofluoric acid and inorganic acid may be supplied separately from the hydrofluoric acid supply unit 36 and the inorganic acid supply unit 38, or only one of them may be supplied.

  FIG. 8 illustrates a case where the polishing unit 13 is in another form. Since the polishing liquid after use of the storage unit 12 is transferred to the Al—F complex removing device 21 and returned to the storage unit 12 as a regenerated polishing liquid, the description is omitted. In FIG. 8, the polishing unit 13 provided in the polishing tank 10 is constituted by an immersion unit 40. The immersion unit 40 includes an immersion tank 42 and an elevator 44. The immersion tank 42 is in communication with the storage unit 12. A circulation pump 42 p provided between the storage unit 12 and the immersion tank 42 circulates the polishing liquid between the storage unit 12 and the immersion tank 42. In addition, you may make the immersion tank 42 and the storage part 12 share.

  The workpiece 90 brought into the polishing tank 10 by the transfer means 24 is immersed in the immersion tank 42 by the elevator 44. The object to be polished 90 is etched by being immersed. The elevator 44 is made of a material having corrosion resistance to the polishing liquid, holds the workpiece 90, can immerse the workpiece 90 in the dipping bath 42, and can pull it up. The workpiece 90 immersed for a predetermined time is pulled up and transferred to the next step by the transfer means 24. Here, the other process may be another polishing apparatus.

  FIG. 9 shows an example in the case of another immersion part 40. In FIG. 9, the immersion tank 42 has a certain length. The polishing liquid circulates between the storage unit 12 and the case of FIG. In FIG. 9, the elevator 44 changes the moving height of the transfer means 41 itself. The workpiece 90 is moved by the transfer means 41 while being immersed in the immersion bath 42. The workpiece 90 is polished while moving in the polishing liquid.

  As described above, the glass polishing method and the polishing apparatus according to the present invention remove the Al—F complex, which is a causative substance of sludge present in the polishing liquid after use, as a sludge by adding a divalent metal salt. . Therefore, almost no Al—F complex remains in the regenerated polishing liquid. Therefore, even if the regenerated polishing liquid is reused, it is possible to suppress the generation of sludge on the glass portion surface of the workpiece 90.

(Embodiment 2)
In the glass polishing apparatus 1 described in the first embodiment, the Al—F complex removal apparatus 21 is configured by the reaction tank 20 and the Al removal metal salt addition unit 22. This is because it is considered effective for reducing defective products that no sludge remains in the reservoir 12 where the polishing liquid is circulating. That is, if sludge remains in the polishing liquid, it is considered that sludge remains on the glass surface during polishing, which is formed as a sludge mark and causes quality deterioration.

  However, the polishing liquid is sprayed or the glass is immersed in the polishing liquid so that it uniformly reaches the surface of the glass to be polished. Furthermore, it is washed with water after polishing. Therefore, even if sludge is mixed in the polishing liquid, it is considered that it is not easy to remain as sludge traces only on the glass surface. In order to remain as sludge traces, it is necessary to adhere to the glass surface, but since sludge is a component insoluble in the polishing liquid, there is little chance of welding with the glass surface.

  That is, it is considered that sludge generated on the glass surface is not the sludge in the liquid phase, but the quality is deteriorated as a sludge mark on the glass surface. Therefore, it was considered that as long as the dissolved Al concentration in the polishing liquid after polishing was lowered, the product quality was not deteriorated even if some sludge was present in the polishing liquid. Therefore, confirmation was performed with the following apparatus. FIG. 10 shows the configuration of the glass polishing apparatus 5. In the glass polishing apparatus 5, the reaction tank 20, the regenerated polishing liquid tank 32, and the flocculant addition unit 26 in the solid-liquid separation unit 25 are removed.

  The Al removal metal salt addition unit 22 is in direct communication with the storage unit 12. Further, the used polishing liquid from the storage unit 12 is directly connected to the filter 28 via the drain pipe 18. The polishing liquid that has passed through the filter 28 returns to the storage unit 12 again by the return pipe 32a.

  The glass polishing apparatus 5 was operated with the Al removal metal salt addition unit 22 stopped. And the polishing liquid in the storage part 12 was sampled for every fixed time, and the elemental analysis was performed by ICP-AES. Further, the sludge concentration (weight) in the sampled polishing liquid and the sludge weight captured by the filter 28 were examined. Further, the appearance evaluation level related to the sludge trace at the time of sampling was examined.

  The sludge concentration was the same as in the first embodiment, and the used polishing liquid after polishing was filtered with a 1 μm filter (PTFE: polytetrafluoroethylene), the sludge was captured, and the amount of sludge generated was measured. The sludge generation amount (mg / L) in the polishing liquid after use of this unit volume was defined as the sludge concentration.

  Further, the weight of the filter 28 was measured every time one piece of glass was polished, and the weight difference with a new dry filter was defined as the MF trapping sludge weight. The MF trapping sludge weight is a weight including the polishing liquid after use (denoted as “g-wet”).

  The appearance evaluation level is an evaluation of the glass surface state after polishing performed by the applicant himself. The appearance evaluation level is determined by the number of visually visible sludge traces. As the number of appearance evaluation levels increases, the number of sludge traces tends to increase. Conversely, if the appearance evaluation level is lowered, it can be said that the number of sludge traces has decreased. In this appearance evaluation level, level 2 or lower is a surface state that does not cause a problem as a product (indicated as “OK” in the figure), and level 3 or higher is not preferable as a product (“NG” in the figure). To the extent that it can be judged.

  FIG. 11A shows changes in each element in the polishing liquid when the glass polishing apparatus 5 is continuously operated. The continuous operation was started from the point when the number of polished sheets was 120 (indicated by a dotted line). The horizontal axis represents the number of processed (polished) sheets. The vertical axis represents the concentration of each element in liquid (mg / L). It can be seen that the content of Al (aluminum) indicated by white circles is higher than that of Sr (black triangle marks), Ca (black square marks), and Mg (black circle marks). In FIG.11 (b), the figure which expanded the vertical axis | shaft and showed only the part of Sr, Ca, and Mg is shown. Al is out of range and is not displayed. For Sr, Ca, and Mg, the concentration oscillated as the number of treatments (polishing) progressed.

  FIG. 12 shows the relationship between the concentration of Sr, Ca, Mg (mg / L) and the sludge concentration (mg / L) in the polishing liquid. The horizontal axis represents the number of processed (polished) sheets. FIG. 12A is the same graph as FIG. 11B, and the vertical axis represents the concentration (mg / L) of each component in the polishing liquid. In FIG. 12B, the left vertical axis represents the sludge concentration (mg / L: black circle mark), and the right vertical axis represents the MF trapping sludge weight (g-wet: white triangle mark).

  Sludge increased (indicated by an upward arrow in FIG. 12 (b)) when the concentration of Sr, Ca, Mg in the polishing liquid decreased (indicated by a downward arrow in FIG. 12 (a)). As shown in FIG. 11A, Al was present at a higher concentration than Sr, Ca, and Mg. Therefore, when Sr, Ca, and Mg have a constant concentration in the polishing liquid, it is considered that sludge is rapidly formed, and at that time, the concentration in the polishing liquid decreases.

  FIG. 13 shows the relationship between the change in the concentration of Sr, Ca, and Mg and the appearance evaluation level. Similarly, the horizontal axis is the amount corresponding to the number of processed (polished) sheets. FIG. 13A shows the same concentration change of Sr, Ca, and Mg as in FIGS. 11B and 12A. That is, the vertical axis represents the concentration (mg / L) of each component. In FIG. 13B, the vertical axis represents the appearance evaluation level. Comparing FIGS. 13A and 13B, it can be seen that the appearance evaluation level tends to increase as the concentration of each component increases.

  Further, the appearance evaluation level when the concentration of each component was increased was unfavorable as a product (becomes NG region). Since the concentration of each component increases periodically, a product that becomes NG periodically appears.

14A and 14B show changes in each element in the abrasive when the Al removal metal salt addition unit 22 is operated and continuously operated in the glass polishing apparatus 5 of FIG. In FIG. 14, the continuous operation was performed from the time when the number of polished sheets was zero. MgCl ₂ was used as the Al removal metal salt. At this time, an amount of magnesium chloride higher than the Al generation rate assumed from the number of treatments (polishing) and the etching rate was added. 14A and 14B, the horizontal axis represents the number of processed (polished) sheets.

  FIG. 14A shows changes in the concentration of Al in the polishing liquid. In FIG. 11A, the Al concentration in the continuous operation was 3000 to 3500 mg / L, whereas in FIG. 14A, it was 200 mg / L or less. That is, the amount of dissolved Al was significantly reduced. In addition, Sr, Ca, and Mg shown in FIG. 14B are 800 mg / L or more, whereas in FIG. 11A, they are 400 mg / L or less. In other words, these elements increased when the Al-removed metal salt was added. Further, these element concentrations did not vibrate.

  FIG. 15A shows changes in sludge concentration and MF trapping sludge weight, and FIG. 15B shows changes in appearance evaluation level. Even when the sludge concentration in FIG. 15A and the MF trapping sludge weight were compared with those in FIG. 12B, the generated concentration was extremely low. The appearance evaluation level shown in FIG. 15B was reduced to almost half. In other words, the glass surface state after polishing was continuously maintained at a level with no problem as a product.

  FIG. 15A and FIG. 12B compare the sludge concentration when the Al removal metal salt is introduced into the reservoir 12 and when it is not. The range of the vertical axis is the same. When an Al-removed metal salt is added, the sludge concentration itself decreases. However, even if the Al removal metal salt is added, sludge is still generated. Nevertheless, at the appearance evaluation level (comparison between FIG. 15 (b) and FIG. 13 (b)), the number of Al-removed metal salts is much less.

  From the above, it can be confirmed that the quality of the product is not deteriorated even if sludge is generated by introducing the Al removal metal salt into the reaction tank 20 and that the quality is sufficient for mass production. It was. Of course, it is more preferable if the reaction tank 20 is provided to forcibly generate sludge and the sludge is removed by the solid-liquid separator 25. However, it can be concluded that there is no reaction vessel 20 as shown in FIG. 10 and that suitable quality can be maintained even if the Al-removed metal salt is directly added to the reservoir 12.

  As described above, the removal of the Al—F complex by the Al removal metal salt may not be performed only in the reaction tank 20 provided therein. Even if an Al-removed metal salt is introduced into the reservoir 12 where the polishing liquid is stored after use, the product quality can be maintained in a high state. Moreover, it has been found that the product quality can be ensured by adding an excessive amount of the Al-removed metal salt even if it is not added in an amount equivalent to Al generated by polishing. Therefore, as shown in FIG. 10, from the glass polishing apparatus 1 shown in FIG. 6, the reaction tank 20, the regenerated polishing liquid tank 32, and the control necessary for calculating an Al-removed metal salt equivalent to the Al generated by polishing. The part 50 can be omitted.

  10 shows a configuration in which the coagulant addition unit 26 is also removed from the solid-liquid separation unit 25, the coagulant addition unit 26 may be provided. This configuration is shown in FIG. The post-use polishing liquid in the storage unit 12 is sent to the solid-liquid separation unit 25 through the drain pipe 18. Then, a flocculant is added in the solid-liquid separation unit 25, the agglomerate is precipitated in the settling tank, the supernatant is filtered through the filter 28, and then returned to the storage unit 12 again.

  The glass polishing apparatus 5 allows a certain amount of sludge to be generated in the storage unit 12. However, it is preferable that the sludge is removed, and the sludge in the storage portion 12 is easily captured by the flocculant. Therefore, it can be said that having the flocculant addition part 26 in the solid-liquid separation part 25 is a preferable structure.

  As described above, the glass polishing apparatus 5 according to the present invention reduces the generation of sludge and the sludge trace generated on the glass to be polished by directly feeding the Al removal metal salt into the storage section 12 where the polishing liquid is stored. can do.

  The glass polishing method according to the present invention can be used without selecting a target product as long as it is polishing of glass containing aluminum.

1, 5 Glass polishing apparatus 10 Polishing tank 10i Inlet 10o Outlet 12 Storage part 13 Polishing part 14 Shower part 14bi Suction port 14b Pipe 14f Filter 14p Polishing liquid pump 14a Pipes 14aa, 14ab Branch pipes 16a, 16b Nozzle 18 Drain pipe 18a Drain port 18b Valve 20 Reaction tank 20a Stirrer 20b Liquid feed pipe 20c Temperature control means 21 Al-F complex removal device 22 Al removal metal salt addition part 22a Metal salt tank 22b Pipe 22c Valve 24 Transfer means 25 Solid-liquid separation part 26 Coagulant addition part 26a Coagulant tank 26b Liquid feed pipe 26c Valve 26d Coagulation tank 26e Liquid feed pipe 26m Stirrer 27 Precipitation tank
27a Partition 27b Liquid feed pipe 28 Filter 28a Liquid feed pipe 32 Recycled polishing liquid tank 32a Return pipe 34 Circulating pump 35 New liquid supply part 36 Hydrofluoric acid supply part 36a Hydrofluoric acid tank 36b Pipe 36c Valve 38 Inorganic acid supply part 40 Immersion part 41 Transfer means 42 Immersion tank 42p Circulation pump 44 Elevator 50 Control part 90 Objects to be polished 91a, 91b Glass part 94 Liquid crystal 93 Shield

Claims (12)

A method for polishing glass containing Al with a polishing liquid containing hydrofluoric acid,
A step of solidifying dissolved Al in the polishing liquid after use after polishing the glass to obtain a polishing liquid after reaction;
A step of solid-liquid separation of the polishing liquid after the reaction to obtain a regenerated polishing liquid;
Having the step of polishing the glass with the regenerated polishing liquid;
The step of obtaining the regenerated polishing liquid includes a step of adding a flocculant to the post-reaction polishing liquid and precipitating a solidified product.   The step of obtaining the post-reaction polishing liquid is a step of adding a salt of at least one element selected from Mg, Ca, Sr, and Ba into the post-use polishing liquid. Glass polishing method.   The glass polishing method according to claim 2, wherein the salt is a salt of an inorganic acid contained in the polishing liquid.   The glass polishing method according to claim 2, wherein the salt is a salt of Mg. A step of calculating the Al concentration in the post-use polishing liquid from the Al content of the glass, the polishing rate of the glass, the cumulative number of polished glass sheets, and the amount of total polishing liquid used for polishing. An Al concentration calculation step,
The glass polishing method according to any one of claims 2 to 4, wherein the salt is added in an amount equal to or less than a molar equivalent in terms of the Al concentration ratio.   The glass polishing method according to any one of claims 1 to 5, wherein the step of obtaining the regenerated polishing liquid includes a step of filtering the post-reaction polishing liquid.   The glass polishing method according to any one of claims 1 to 6, wherein the flocculant is a nonionic substance. A reservoir for storing the polishing liquid;
A polishing part that makes Al-containing glass and the polishing liquid contact each other, and returns the used polishing liquid after contact to the storage part,
A reaction vessel to which at least a part of the post-use polishing liquid in the reservoir is transferred;
A metal salt tank that communicates with the reaction vessel and stores a metal salt that removes dissolved Al in the polishing liquid after use;
A solid-liquid separation unit for solid-liquid separation of the post-reaction polishing liquid obtained from the reaction vessel;
A recycled polishing liquid tank communicated with the solid-liquid separator;
A return pipe that communicates the reclaimed polishing liquid tank and the reservoir;
Information including the amount of polishing liquid transferred to the reaction vessel, the polishing rate, the Al content in the glass, the polishing amount, and the amount of reclaimed polishing liquid supplied from the reclaimed polishing liquid tank to the reservoir. A glass polishing apparatus comprising: a control unit that calculates the amount of metal salt charged into the reaction tank based on the control unit. A new liquid supply unit for supplying a new liquid to the storage unit;
Glass polishing apparatus according to claim 8, characterized in that it includes a new liquid supply amount to said information.   The solid-liquid separation unit is configured by a precipitation tank to which a flocculant addition unit is connected and the polishing liquid after the reaction is transferred, and a filter for filtering the supernatant liquid of the precipitation tank. A glass polishing apparatus according to claim 1.   The glass polishing apparatus according to any one of claims 8 to 10, wherein the polishing unit includes a shower unit that sprays the polishing liquid onto the Al-containing glass.   The glass polishing apparatus according to any one of claims 8 to 10, wherein the polishing unit includes an immersion unit for immersing the Al-containing glass in the polishing liquid.