KR20050046913A - Method of recycling abrasive grains for forming barrier ribs of plasma display panel - Google Patents

Abstract

 In the regeneration method of the PDP partition wall polishing powder according to the present invention, an alkaline aqueous solution is used for the frit glass and the cellulose-based polymer component remaining in the polishing waste after performing the PDP partition wall polishing step by sandblasting using the polishing powder. It is characterized by regenerating the polishing powder in the polishing waste by removing by a chemical washing process. Since the present invention does not use an organic solvent, the environment is simple and the process is simple. According to the present invention, the regeneration of the PDP partition wall polishing powder is almost perfect, resulting in a large cost reduction effect.

Description

Method of recycling abrasive grains for forming barrier ribs of plasma display panel

The present invention relates to a method for regenerating powder for polishing PDP barrier ribs, in particular, by removing the frit glass and cellulose-based polymer components remaining in the abrasive waste after the PDP barrier rib polishing process by sandblasting method by an environmentally friendly method. The present invention relates to a method for regenerating PDP partition wall polishing powder.

In general, plasma display panels (PDPs), which are widely attracting attention as next generation displays, include electrodes, barrier ribs, dielectrics, passivation layers, phosphors, driving circuits, and the like. In particular, barrier ribs may include respective discharge cells. This is to distinguish between and plays a very important role in preventing electrical and optical crosstalk between adjacent cells. The bulkhead is about 100 mu m wide and about 200 mu m high, and is formed by screen printing, sandblasting, or squeezing.

1A to 1G are cross-sectional views illustrating a method of forming a partition wall of a PDP by a sandblasting method, and refer to those disclosed in Korean Patent Application No. 97-2096.

First, as shown in FIG. 1A, the barrier material 3a is coated on the back substrate 2 of the PDP to a thickness of 100 to 200 μm, and then the dry film 21 is 15 to 100 on the barrier material 3a as shown in FIG. 1B. Coating to μm thickness.

1C, light 23 is selectively irradiated onto the dry film 21 using the mask 22 (exposure step). Then, the chemical composition of the portion irradiated with the light 23 and the portion not irradiated of the dry film 21 is changed.

Next, as shown in FIG. 1D, the developer 24a is supplied onto the dry film 21 using the developer supply nozzle 24 to selectively remove only the portion of the dry film 21 not irradiated with light 23 ( Developing process)

Subsequently, the abrasive powder 25a is sprayed onto the partition material 3a using the abrasive powder injection nozzle 25 as shown in FIG. 1E. Then, as shown in FIG. 1F, the portion under the remaining dry film 21 of the partition material 3a remains protected from the polishing powder 25a and the remaining portion is removed by the polishing powder 25a ( Sandblast process)

Then, when the remaining dry film 21 is peeled off, the partition 3 is completed as shown in FIG. 1G.

Al ₂ O ₃ powder, SiC powder, glass powder, stainless steel powder, or the like may be used as the polishing powder 25a used in the sandblasting method described above.

In the sand blasting process of removing the partition material 3a with the abrasive powder 25a, abrasive waste is generated. The abrasive waste includes frit glass and polymer resin components contained in the waste abrasive powder and the partition material 3a. This exists.

The waste polishing powder occupies approximately 10 to 40 wt%, and the frit glass is present in the form of a mixture with the waste polishing powder in powder form or adsorbed on the surface of the polishing powder. The frit glass has PbO, Al ₂ O ₃ , and SiO _{2 as} main components. The polymer resin component, which is used as a binder, is cellulose-based and mainly exists in an adsorbed state on the surface of the waste polishing powder.

Up to now, since the entire abrasive waste is landfilled, it is a cause of environmental pollution, and it is expensive to prepare polishing powder.

Therefore, the technical problem to be achieved by the present invention is the polishing powder after use by removing the frit glass and cellulose-based polymer components remaining in the polishing waste after the PDP partition wall polishing process by the sandblasting method in an environmentally friendly manner. The present invention provides a method for regenerating powder for polishing a PDP barrier rib, which is returned to the same state as before use.

In order to achieve the above technical problem, a method for regenerating PDP bulkhead polishing powder according to the present invention includes frit glass and cellulose-based polymer remaining in abrasive waste after performing PDP partition wall polishing by sandblasting using abrasive powder. The polishing powder in the polishing waste is regenerated by removing the component by a chemical washing process using an aqueous alkali solution.

As the aqueous alkali solution, one containing at least one selected from the group of inorganic alkalis consisting of sodium hydroxide, potassium hydroxide, and ammonia can be used. In addition, as the aqueous alkali solution, one containing at least one selected from the group of organic alkalis consisting of primary amines having 1 to 10 carbon atoms, secondary amines, and tertiary amines may be used.

It is more preferable if the alkali aqueous solution contains an anionic surfactant containing an alkyl group. In this case, as the anionic surfactant, sodium dodecyl sulfate, sodium linear dodecyl phenyl sulfate, ammonium steary sulfate, and sodium myristyl phosphate ( sodium myristyl phosphate) may be used including at least one selected from the group consisting of.

If the regeneration is not performed properly, the PDP partition wall polishing efficiency of the regenerated powder is reduced by the remaining of the frit glass, and the regeneration powder is disturbed by the residual of the organic polymer component, resulting in poor polishing of the PDP partition wall.

Therefore, in order to ensure the regeneration, it is better to perform the regeneration treatment by the above chemical method than the physical method. Although organic solvents such as alcohols and ketones may be used for regeneration, this is not preferable because of the high processing cost and the use of organic solvents, which may cause more environmental pollution.

Meanwhile, the method may further include a step of dry classifying the frit glass and the polishing powder in the polishing waste with a dry classifier before the chemical washing process.

The frit glass powder mixed in a large amount in the abrasive waste has a specific gravity of about 1.4 and an average particle diameter of 1 μm or less, which is very different from the polishing powder. For example, in the case of stainless steel polishing powder, specific gravity is about 4-5, and average particle diameter is about 12-18 micrometers. Therefore, since the frit glass powder may be selectively removed between them through a physical classification process, the above-described dry classification process may be further performed.

However, the fine frit glass and the polymer resin component remaining on the surface of the polishing powder cannot be removed by such a dry classification process and can be removed only by the above-described chemical method.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

The following examples are only presented to understand the content of the present invention, and those skilled in the art may make many modifications within the technical spirit of the present invention. Accordingly, the scope of the present invention should not be construed as being limited to these embodiments.

Figure 2 is a process flow chart for explaining the PDP partition wall regeneration method for polishing according to the present invention.

First, the PDP bulkhead grinding waste is classified into various types of sieving or forced vortex dry classifiers (S10). The classification of the sifting type classifier is a waste feed rate of 5 ~ 50kg / hr, preferably 10 ~ 20kg / hr. The classification of the forced vortex classifier is a waste input speed of 10 ~ 500kg / hr, preferably 100 ~ 200kg / hr, the rotor speed of the classifier is 500 ~ 5000rpm, preferably 1000 ~ 2500rpm do. Compressed air is preferably 0.05 MPa, preferably 0.1 to 0.2 MPa.

Next, as a first step of the chemical process (S20) to prepare a slurry (Slurry) (S20-1). Specifically, the surfactant is added to the aqueous alkali solution, and the polishing waste which has been subjected to the classification process is added thereto and mixed with a stirrer to prepare a slurry of 0.01 to 50 wt% at 10 to 100 ° C., preferably 60 to 80 ° C. (slurry) is prepared.

At this time, the concentration of the aqueous alkali solution is preferably 0.001 ~ 10wt%, more preferably 0.001 ~ 5wt%. The surfactant is preferably added by 0.001 to 2.5wt% with respect to the aqueous alkali solution, and more preferably added by 0.01 to 1wt%.

When not going through the dry classification process (S10), the concentration of the aqueous alkali solution is preferably 0.01 to 20wt%, more preferably 0.5 to 10wt%. In addition, the surfactant is preferably added by 0.01 to 5wt% with respect to the aqueous alkali solution, more preferably by 0.02 to 1wt%.

The stirring speed during the slurry preparation is preferably 300 to 2000 rpm so that the frit glass powder mixed in the abrasive waste is sufficiently dispersed and reacted with alkali ions.

Subsequently, as a second step of the chemical process (S20), a filtration process for removing water is performed (S20-2). The mother liquor is removed from the slurry by using a Nutsche filter, a filter press, a centrifuge or a decantation method after settling to obtain a cake. Then, the cake obtained at this time is slurried again in water, and the mother liquor removal method as described above is repeated to wash until a transparent mother liquor comes out.

Subsequently, the cake obtained by the filtration step (S20-2) is subjected to general drying steps such as hot air drying, vacuum drying, spray drying, and freeze drying to obtain a powder for regeneration polishing (S20-3).

Example 1

Dry classification process: Classify abrasive waste by forced vortex type dry classifier. At this time, classification condition is 100 kg / hr of waste input, rotor speed of 1000 rpm and compressed air 0.1 MPa. Shall be.

Slurry Preparation: 4 kg of 5 wt% NaOH aqueous solution, 0.05 g sodium dodecyl sulfate, and 1 kg of sorted abrasive waste were added to a 5 L beaker, mixed, and then stirred with a high speed stirrer to form a slurry. The stirring speed at this time is 1000rpm, the reaction temperature of the slurry is 80 ℃, the reaction time is 2 hours.

Filtration: The mother liquor was completely removed from the slurry using a 2000 rpm centrifuge, and the cake thus obtained was slurried again in water and washed three to four times in the same manner until the mother liquor became transparent.

Drying: The cake obtained by the filtration process is dried at 110 ° C. for 24 hours using a hot air dryer to obtain regenerated stainless steel powder.

FIG. 3A is a polishing waste, FIG. 3B is a regular product before being used for polishing, and FIG. 3C is a SEM photograph of a recycled powder. Table 1 shows the EDX analysis results of FIGS. 3A to 3C.

It can be seen that the shape of the recycled powder (FIG. 3C) and the distribution of impurities are completely different from the abrasive waste (FIG. 3A), and are almost the same as the regular product 3b. In particular, referring to Table 1, it can be seen that the regeneration powder (FIG. 3C) does not contain Pb, which is a main component of the frit glass, which means that the frit glass is completely removed by the regeneration process.

Example 2

Dry classification process: Abrasive wastes are classified by dry vortex type classifier. In this case, the classification conditions are 50kg / hr of waste input, rotor speed of 1500rpm and compressed air of 0.05MPa. Shall be.

Slurry Preparation: 8 kg of 1 wt% KOH aqueous solution, 0.05 g of ammonium steary sulfate, and 2 kg of the sorted abrasive waste were added to a 10 L beaker and mixed, followed by stirring with a high speed stirrer to form a slurry. The stirring speed at this time is 5000rpm, the reaction temperature of the slurry is 30 ℃, the reaction time is 2 hours.

Filtration: The mother liquor is completely removed using a Nutsche filter, and the cake obtained is slurried again in water and washed three to four times in the same manner until the mother liquor becomes transparent.

Drying: The cake obtained by the filtration process is dried at 700 mmHg at 90 ° C. for 12 hours using a vacuum dryer to obtain regenerated stainless steel powder.

Example 3

Dry Classification Process: No

Slurry Preparation: 8 kg of 5 wt% aqueous solution of ethylenediamine, 0.05 g of sodium myristyl phosphate, and 2 kg of unclassified abrasive waste were added to a 10 L beaker and mixed, followed by stirring with a high speed stirrer to form a slurry. The stirring speed at this time is 1500rpm, the reaction temperature of the slurry is 70 ℃, the reaction time is 2 hours.

Filtration: The mother liquor is completely removed using a filter press, and the cake thus obtained is slurried again in water and washed 7 to 8 times until the mother liquor becomes transparent in the same manner.

Drying: The cake obtained by the filtration process is dried at 700 mmHg at 90 ° C. for 12 hours using a vacuum dryer to obtain regenerated stainless steel powder.

[Table 1] Results of EDX Analysis

                                     unit:%

waste Recyclable Regular article Fe 33.098 75.859 75.798 Cr 10.790 20.003 20.423 Al 9.907 1.838 1.779 Mn 0.421 0.986 0.969 Si 4.127 0.578 0.507 Ti 2.401 0.516 0.39 Pb 30.652 ND ND Ni ND 0.059 0.069 Tl ND 0.056 0.065 S 6.053 0.057 ND Zn ND 0.05 ND V 0.07 ND ND Th 0.857 ND ND Ir 1.625 ND ND

The present invention for removing the frit glass and the polymer resin component present in the abrasive waste by chemical method using an aqueous alkali solution is environmentally friendly and simple to process since it does not use an organic solvent. According to the present invention, the regeneration of the PDP partition wall polishing powder is almost perfect, resulting in a large cost reduction effect.

1A to 1G are cross-sectional views illustrating a method of forming a partition wall of a PDP by sandblasting;

2 is a process flow chart for explaining a PDP partition wall powder regeneration method according to the present invention;

 FIG. 3A is a polishing waste, FIG. 3B is a regular product before being used for polishing, and FIG. 3C is a SEM photograph of a recycled powder.

<Description of reference numbers for the main parts of the drawings>

2: back substrate 3a: partition material

21: dry film 22: mask

23: light 24: supply nozzle

24a: Developer 25: Abrasive Powder Spray Nozzle

25a: abrasive powder

Claims (7)

Polishing powder in the polishing waste by removing the frit glass and cellulose-based polymer components remaining in the polishing waste after performing the PDP partition wall polishing process using the polishing powder by sand blasting by a chemical washing process using an aqueous alkali solution. PDP bulkhead polishing powder regeneration method, characterized in that for regenerating. The method of claim 1, wherein the aqueous alkali solution comprises at least one selected from the group of inorganic alkalis consisting of sodium hydroxide, potassium hydroxide, and ammonia. The powder regeneration for PDP partition wall polishing according to claim 1, wherein the aqueous alkali solution includes at least one selected from an organic alkali group consisting of primary amines, secondary amines, and tertiary amines having 1 to 10 carbon atoms. Way. The powder regeneration method for polishing PDP barrier ribs according to claim 1, wherein the aqueous alkali solution contains an anionic surfactant containing an alkyl group. The PDP of claim 4, wherein the anionic surfactant comprises at least one selected from the group consisting of sodium dodecyl sulfate, sodium linear dodecyl phenyl sulfate, ammonium stearyl sulfate, and sodium myristyl phosphate. Recycling method for bulkhead grinding. The method of claim 1, further comprising: dry classifying the frit glass and the polishing powder in the polishing waste with a dry classifier before the chemical washing process. The method of claim 1, wherein the polishing powder is Al ₂ O ₃ powder, SiC powder, glass powder, or stainless steel powder.