KR101607729B1 - In-line reusing method for cleaning solution for preparing a polizer comprising potassium iodied and boric acid for preparing a polizer - Google Patents

Abstract

The present invention relates to a method of in-line reuse of a cleaning solution for the production of polarizers comprising potassium iodide and boric acid, and more particularly to a method of recovering a cleaning solution containing potassium iodide and boric acid in a washing facility for producing polarizers, Storing; Introducing the stored cleaning solution into a membrane having a selective permeability according to molecular weight and charge to separate the potassium iodide and boric acid-containing fractions from the cleaning solution; And a step of charging the fraction into a polarizer manufacturing facility and reusing it for preparing a polarizer, thereby maximally recovering and reusing active ingredients such as potassium iodide and boric acid, thereby avoiding waste of cost and deterioration of productivity of the polarizer To a method for in-line reuse of a cleaning solution for polarizer production.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for in-line reuse of a cleaning solution for preparing a polarizer comprising potassium iodide and boric acid. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002]

The present invention relates to a method for in-line recycling of a cleaning solution comprising potassium iodide and boric acid in the production process of a polarizer.

A polarizing plate used for a liquid crystal display (LCD) or the like has a multilayer structure in which a polarizer and a protective film typified by triacetylcellulose (TAC) film are laminated on one or both sides thereof.

A polarizer enables to obtain polarized light having a vibration plane in a predetermined direction when natural light is passed through. The polarizer is a polarizing plate in which an iodine polarizer in which iodine is adsorbed and oriented on a polyvinyl alcohol (PVA) film, a dichroic dye is adsorbed An oriented dye-based polarizer or the like is used. In particular, iodine polarizers are most widely used because of their excellent optical properties such as transmittance and polarization degree.

Polarizers are typically prepared by swelling, dyeing and crosslinking PVA films. The dyeing process includes a step of impregnating the swollen PVA film into a dyeing bath containing iodine (I ₂ ), potassium iodide (KI), boric acid and the like in order to dye iodine on the swollen PVA film. The crosslinking step includes a step of impregnating a PVA film with a crosslinking bath containing iodide (KI), boric acid or the like after the iodine is stained through stretching. The cleaning step is a step of removing foreign matter remaining on the surface of the crosslinked PVA film with a cleaning solution such as water.

When the PVA film is repeatedly impregnated with the water bath used in the washing process, the treatment solution used in the previous process, such as potassium iodide and boric acid, is dissolved and contained in the cleaning solution in addition to the dust and impurities remaining on the surface of the PVA film do. However, conventionally, when the washing power of the washing solution is lowered, all the washing solution is discarded and potassium iodide or boric acid is also discarded.

In order to solve this problem, for example, in Korean Patent No. 781566, a waste solution of potassium iodide stored in a storage tank is purified by colorless and transparent contact with activated carbon, the fine particles having a predetermined size or larger are filtered out, And a method of refining the potassium iodide waste solution by filtering the foreign matter again with a nanofilter. However, this purification method focuses only on the purification of potassium iodide, which limits the difficulty of applying to the purification of other components of the solution of the polarizer. In addition, since the potassium iodide solution is stored in a separate reservoir, There is a problem in that it can not be reused immediately after purification in a polarizer manufacturing process.

In addition, there have been other attempts to treat wastewater by the methods such as coagulation, adsorption, microbial treatment, etc., but the purification effect of PVA has not been satisfactory because it is difficult to remove the degradable PVA.

Korean Patent No. 781566

It is an object of the present invention to provide a continuous reuse method of a cleaning solution comprising potassium iodide and boric acid which can be implemented in a polarizer manufacturing process.

It is an object of the present invention to provide a method for reusing an effective component such as potassium iodide, boric acid and the like contained in a cleaning liquid by filtering the cleaning solution so as to be used in the production process of the polarizer.

1. Recovering a cleaning solution containing potassium iodide and boric acid in a washing facility for polarizer production and storing the cleaning solution in a first buffer tank; Introducing the stored cleaning solution into a membrane having a selective permeability according to molecular weight and charge to separate the potassium iodide and boric acid-containing fractions from the cleaning solution; And introducing the fraction into a polarizer manufacturing facility and reusing it for polarizer production.

2. The method of claim 1, further comprising refluxing the fraction to the first buffer tank and then flowing it into the membrane to concentrate potassium iodide and boric acid in the fraction.

3. The method of claim 1, further comprising concentrating the separated fraction solution so that the concentration of potassium iodide in the fraction is less than 10% of potassium iodide in the manufacturing solution in the polarizer manufacturing facility.

4. The method of recycling as recited in claim 1, further comprising adjusting the temperature of the fraction solution to less than 10% of the temperature of the production solution in the manufacturing facility.

5. The method of recycling 1 or 2 above, further comprising discharging the fraction to discard the separated cleaning solution.

6. The method of claim 5, wherein the fraction is stored in a second buffer tank prior to discharging the separated cleaning solution, the stored cleaning solution is introduced into a membrane having selective permeability according to molecular weight and charge, Separating the fraction containing potassium and boric acid and transferring the fraction to the first buffer tank.

7. The method of recycling as recited in claim 1 further comprising monitoring the concentration of potassium iodide and boric acid.

8. The method of recycling as recited in 1 above, further comprising passing a filter having a pore size of 0.1-10 mu m before introducing said cleaning solution into said membrane.

9. The reuse method according to 1 above, wherein the water washing facility is a water bath provided in a line or a water bath tank circulating and supplying a wash water solution to the water bath.

10. The method of 1 above, wherein the manufacturing facility is a dyeing facility, a bridging facility, or both.

11. The recycling method according to item 1 above, wherein the polarizer cleaned with the cleaning solution of the water washing equipment is preliminarily removed from the process for removing polyvinyl alcohol in the polarizer manufacturing facility of the previous process.

12. The method of claim 11, wherein the step of removing the polyvinyl alcohol foreign substance comprises the steps of: recovering a preparation solution containing polyvinyl alcohol as a foreign substance in the polarizer manufacturing facility and storing the solution in a buffer tank; Introducing the stored preparation solution into a membrane having selective permeability according to molecular weight to separate the polyvinyl alcohol-containing fraction from the preparation solution; And introducing the production solution from which the fraction has been removed into the production facility and reusing it for production of a polarizer.

13. The method of claim 12, further comprising refluxing the fraction to the buffer tank and then flowing it into the membrane to concentrate the polyvinyl alcohol in the fraction.

14. The method of recycling according to claim 12, further comprising the step of concentrating the production solution from which the fraction has been removed such that the composition ratio of the production solution from which the fraction is removed is less than 10% .

15. The method of claim 12 further comprising adjusting the temperature of the manufacturing solution from which the fraction has been removed to be less than 10% of the temperature of the manufacturing solution in the manufacturing facility.

16. The method of recycling according to 12 or 13 above, further comprising discharging said fraction for disposal.

17. The method of recycling according to 12 above, wherein the preparation solution from which the fraction has been removed is a dyeing solution, a crosslinking solution or both.

18. The method of recycling according to 17 above, wherein the production solution from which the fraction is removed contains at least one selected from the group consisting of iodine, potassium iodide and boric acid.

19. The method of recycling according to 18 above, further comprising monitoring at least one concentration selected from the group consisting of iodine, potassium iodide and boric acid.

20. The method of recycling according to 12 above, further comprising the step of passing a filter having a pore size of 0.1-10 mu m prior to introducing the preparation solution into the membrane.

21. The recycling method of claim 12, wherein the manufacturing facility is a solution tank installed in a line or a solution tank for circulating and supplying a solution for preparation in the solution tank.

22. The method of recycling according to 12 above, wherein said film does not transmit those having a molecular weight of 300 or more.

23. The method of recycling according to 12 above, wherein said membrane further has a selective permeability according to the ionic charge repulsion.

24. The method of recycling according to 13 above, wherein the concentration of said concentrated polyvinyl alcohol is from 10 to 100,000 ppm.

25. The method of recycling according to 14 above, wherein the preparation solution from which the fraction is removed contains 0.001 to 0.1 mol / L of iodine, 0.001 to 15% by weight of potassium iodide, or 0.001 to 8% by weight of boric acid.

26. The method of recycling according to 15 above, wherein the production solution from which the fraction has been removed has a temperature of from 20 to 60 캜.

27. The method of claim 12, further comprising the step of passing a safety filter having an air pore size of 0.1 - 10 [mu] m prior to introducing the manufacturing solution from which the fraction has been removed into the manufacturing facility.

The reuse method of the present invention is advantageous in that it can be used again in the process for producing polarizers by selectively separating the effective components such as potassium iodide and boric acid contained in the cleaning solution of the polarizer.

The reuse method of the present invention is constituted by an in-line process of a manufacturing process which is in operation for producing a polarizer, so that the cleaning solution can be purified from time to time without interrupting the manufacturing process.

The re-use method of the present invention can recover potassium iodide and boric acid in the cleaning solution, thus contributing to a reduction in the production cost of the polarizer.

The reuse method of the present invention is constituted by an in-line process of a polarizer manufacturing process, and is configured to have independence, and maintenance, repair, and improvement are possible separately from the manufacturing process.

The reuse method of the present invention is more efficient and economical than the conventional methods of selectively separating only a part of the effective components such as potassium iodide and boric acid contained in the cleaning solution.

The reuse method of the present invention can maximize the recovery of effective components such as potassium iodide and boric acid contained in the cleaning solution.

The reuse method of the present invention can improve the productivity of the polarizer and is effective in saving limited resources such as iodine and boric acid and improving environmental problems.

1 is a cleaning solution recycling system according to an embodiment of the present invention.
Fig. 2 shows the concentration change trends according to the re-input order of potassium iodide in the reuse system of the embodiment.
FIG. 3 shows the concentration change trends depending on the degree of re-introduction of boric acid and the increase in boric acid recovery rate according to the concentration method change in the reuse system of the embodiment.
4 is a polyvinyl alcohol purification system according to an embodiment of the present invention.
FIG. 5 shows changes in concentration of polyvinyl alcohol (PVA) and total organic carbon contained in a solution for preparation in a solution tank of the polyvinyl alcohol refining system of the embodiment with time.
Fig. 6 shows the concentrations of iodine contained in each of the preparation solutions before and after purification by the polyvinyl alcohol refining system of the examples.
FIG. 7 shows the concentrations of potassium iodide contained in the preparation solutions before and after purification by the polyvinyl alcohol refining system of the examples, respectively.
Fig. 8 shows the concentrations of boric acid contained in each of the preparation solutions before and after purification by the polyvinyl alcohol refining system of the examples.
9 shows the recovery rates of iodine, potassium iodide and boric acid by the polyvinyl alcohol refining system of the examples.

The present invention relates to a method for recovering a cleaning solution containing potassium iodide and boric acid in a washing facility for polarizer production and storing the cleaning solution in a buffer tank; Introducing the stored cleaning solution into a membrane having a selective permeability according to molecular weight and charge to separate the potassium iodide and boric acid-containing fractions from the dyeing solution; And a step of injecting the fraction into a polarizer crosslinking facility and reusing it for producing a polarizer, thereby maximally recovering and reusing active ingredients such as potassium iodide and boric acid, thereby avoiding waste of cost and deterioration of polarizer productivity To a method for in-line reuse of a cleaning solution for polarizer production.

Hereinafter, the present invention will be described in detail.

The cleaning solution recycling method of the present invention is to treat the cleaning solution used in the polarizer manufacturing process. Water (water) is usually used as the original solution of the cleaning solution supplied to the cleaning tank before being used in the polarizer manufacturing process. However, when such a cleaning solution is used in the polarizer manufacturing process, impurities remaining on the surface of the polarizer, processing chemicals in a previous process such as potassium iodide, boric acid, and the like may contaminate the cleaning solution.

The reuse method of the present invention includes a step of recovering a cleaning solution containing potassium iodide and boric acid in a washing facility for polarizer production and storing the cleaning solution in a buffer tank. The upper water washing facility may be a water bath installed on a line in which the polarizer film is impregnated, or a water bath tank circulating and supplying wash water to the water bath.

The amount of the cleaning solution recovered in the buffer tank and the recovery frequency of the cleaning solution can be appropriately adjusted according to the reuse capacity, the content of foreign matter, the operating conditions of the polarizer manufacturing process, and the like.

The reusing method of the present invention includes a step of introducing the cleaning solution stored in a buffer tank into a membrane having a selective permeability according to molecular weight and charge to separate the potassium iodide and boric acid-containing fractions from the dyeing solution.

Since the cleaning solution used is mostly water, when water is introduced into the membrane, the water component permeates the membrane and the potassium iodide or boric acid can not permeate the membrane and can be separated. The membrane used in the reuse method of the present invention is not particularly limited as long as it is capable of separating potassium iodide and boric acid from other components of the cleaning solution. For example, the film forming conditions of the flat membrane constituting the membrane may be changed or the membrane may be subjected to a surface treatment for separation so that potassium iodide and boric acid are separated from other components of the cleaning solution.

More specifically, since potassium iodide and boric acid are very small in size, separation of potassium iodide and boric acid from the cleaning solution is performed by using a membrane having both physical size (molecular weight) and chemical characteristics (electrostatic force by charge) .

The cleaning solution may be introduced into the membrane from the buffer tank through suitable means. For example, a transporting device such as a pump can be used so that the cleaning solution can flow into the membrane at a constant pressure.

The fraction containing potassium iodide and boric acid includes potassium iodide and boric acid, but the content of potassium iodide and boric acid may be small depending on the performance of the membrane or the composition of the cleaning solution before purification. Since the amount of potassium iodide and boric acid in the fraction increases with the repetition of the membrane separation step by reflux, the concentration of potassium iodide and boric acid in the fraction can be increased through this reflux and concentration process.

Thus, when this reflux and concentration process is repeated, the concentration can be adjusted to be similar to the concentration of the crosslinking solution (solution made in the intended composition) used in other manufacturing processes of the polarizer, for example, a crosslinking process. Since potassium iodide is easier to separate than boric acid, the concentration of potassium iodide in the separated fraction becomes higher than that of boric acid.

Regarding waste treatment, it is also possible to reduce the amount of waste discharged because potassium iodide and boric acid are removed by repeating the step of introducing into the membrane.

The reutilization method of the present invention includes the step of injecting a fractionated solution containing separated potassium iodide and boric acid into a polarizer manufacturing facility and reusing it for polarizer production. The above manufacturing facility may be a dyeing facility, a bridge facility, or both. The dyeing equipment or crosslinking equipment may be a dyeing tank or a crosslinking tank installed in a line impregnated with a polarizer film or a dyeing tank for circulating and supplying a dyeing solution to the dyeing tank or a crosslinking tank for circulating and supplying a crosslinking solution to the crosslinking tank.

According to the method of the present invention, the fraction containing potassium iodide and boric acid can be concentrated to be used in a polarizer manufacturing facility. As described above, since the concentration of potassium iodide in the separated fraction is higher than the concentration of boric acid, it is preferable to determine the composition ratio of the fraction to be added to the production facility based on potassium iodide. For example, the concentration of potassium iodide in the fraction may be less than 10% of the potassium iodide in the manufacturing solution in the polarizer manufacturing facility. In addition, the fraction containing potassium iodide and boric acid and the like may be repeatedly refluxed and concentrated so that the difference in the concentration of potassium iodide can be substantially reduced. For this, the concentration of potassium iodide and boric acid can be monitored.

According to the method of the present invention, the fractional solution can be adjusted so that the composition ratio, as well as the temperature of the solution, before the composition is put into the production facility, is substantially the same as that of the original crosslinking solution by employing a temperature control unit. For example, the temperature difference between both may be less than 10%.

In order to finely adjust the concentration and temperature of the fraction solution, the fraction solution separated from the membrane may be collected in a certain storage tank and then introduced into the manufacturing facility. When transferring the fraction solution from the storage tank to the crosslinking facility, a conveying means such as a pump may be used.

The cleaning solution from which potassium iodide and boric acid fractions have been removed can be discharged collectively for disposal or can be discharged separately if necessary. Disposal of the cleaning solution from which potassium iodide and boric acid have been removed can be appropriately carried out according to the operating conditions of the reuse process. For example, it can be carried out from several days to several weeks.

In the reusing method of the present invention, potassium iodide and boric acid fractions are stored in a second buffer tank before discharging the separated cleaning solution, and the stored cleaning solution is introduced into a membrane having a selective permeability according to molecular weight and charge, Separating the fraction containing potassium iodide and boric acid from the solution, and transferring the separated fraction to the first buffer tank. The concentration of potassium iodide and boric acid can be further increased through the two-stage concentration process.

In the reusing method of the present invention, a filtering process may be further included in order to remove foreign matter that may be included in the transferring and processing of the cleaning solution before each step, if necessary. For example, before the washing solution containing potassium iodide and boric acid is introduced into the separation membrane, the foreign matter generated in the feeding process of the washing solution is passed through a filter having a pore size of 0.1-10 μm according to the size of the foreign substance, And a purified filter solution having a pore diameter of 0.1 to 10 탆 can be passed through the safety filter according to the size of the foreign matter before the purified solution is injected into the crosslinking facility to remove foreign matter generated in the crosslinking facility.

In the present invention, the polarizer cleaned with the cleaning solution in the water washing equipment may be a process for removing the polyvinyl alcohol foreign substance in advance in the polarizer manufacturing facility of the previous process. In the production process of the polarizer, the polarizer component may be polyvinyl alcohol separated from the polarizer and present as a foreign substance in the production solution. Since the polyvinyl alcohol has a molecular size larger than that of potassium iodide or boric acid, when the polyvinyl alcohol is present in the cleaning solution, the polyvinyl alcohol is separated from the separation membrane for reuse of the cleaning solution together with potassium iodide or boric acid, It may be the cause.

Therefore, when the polyvinyl alcohol foreign matters are removed from the surface of the polarizer before the cleaning step, the polyvinyl alcohol can be prevented from being contained in the cleaning solution, and thus polyvinyl alcohol can be used in the separation membrane for reuse of the cleaning solution together with potassium iodide or boric acid Separation can be prevented.

One embodiment of the polyvinyl alcohol foreign matter removal process that can be performed before the reuse process of the cleaning solution according to the present invention is to recover the preparation solution containing polyvinyl alcohol as a foreign substance in a facility for producing polarizers, Separating the fraction containing the polyvinyl alcohol from the solution for preparation by introducing the stored solution for preparation into a membrane having a selective permeability according to molecular weight, and introducing the solution for preparation into which the fraction is removed into the manufacturing facility And reusing it for polarizer production.

This will be described in more detail as follows.

The method for removing foreign matter of polyvinyl alcohol according to the present invention is to treat a solution for production used in a polarizer manufacturing process. Preferably, the dyeing solution, the crosslinking solution, or both used in the dyeing step, the crosslinking step, or both of them in the production step can be treated.

The solution for preparation generally contains at least one or more of iodine (I ₂ ) as a dyeing component, potassium iodide (KI) as a dissolution aid, and boric acid as a crosslinking aid for crosslinking a polyvinyl alcohol film and an iodine molecule, And may further include other components.

The concentration of the above active ingredients in the preparation solution need not be included in a specific range, but it is preferable that the concentration is, for example, 0.001 to 0.1 mol / L of iodine, 0.001 to 15 wt% of potassium iodide and 0.001 to 8 wt% of boric acid.

The temperature of the production solution used in the polarizer manufacturing process is, for example, 20 to 60 캜, preferably 30 to 50 캜.

If the polyvinyl alcohol film is repeatedly impregnated into the preparation solution in the polarizer manufacturing process, polyvinyl alcohol or the like is detached from the film and enters the preparation solution and contaminates the production solution.

The method for removing a polyvinyl alcohol foreign matter of the present invention includes recovering a production solution contaminated with polyvinyl alcohol in a manufacturing facility of a polarizer manufacturing process and storing the solution in a buffer tank. The above manufacturing facility means, for example, a solution tank provided on a line in which a film is impregnated, or a solution tank circulating and supplying a solution for preparation in the solution tank.

The amount of the preparation solution recovered in the buffer tank and the recovery frequency of the solution for preparation can be appropriately adjusted according to the purification capacity, the content of foreign matter, the operating conditions of the polarizer manufacturing process, and the like.

The method of removing polyvinyl alcohol foreign matter according to the present invention includes a step of introducing a solution for preparation stored in a buffer tank into a membrane having selective permeability according to molecular weight to separate polyvinyl alcohol-containing fractions from the solution for preparation do.

The polyvinyl alcohol has a molecular weight (weight average molecular weight) of, for example, 1,000 to 1,000,000. Most of the polyvinyl alcohol chains separated from the film have a molecular weight of several hundred to several thousands. Therefore, when a solution for preparation contaminated with an organic substance such as polyvinyl alcohol flows into the above membrane, organic substances such as polyvinyl alcohol can not pass through the membrane, and compounds such as iodine, potassium iodide, and boric acid permeate the membrane to form polyvinyl alcohol- Is separated from the preparation solution.

The above organic materials include plasticizer organic substances such as glycerin contained in the preparation solution for processing polyvinyl alcohol, various impurity organic substances, and the like.

The membrane used in the method for removing foreign matters of polyvinyl alcohol of the present invention is not limited to the one having a specific structure or made of a specific material and is particularly limited as long as it can separate organic matters such as polyvinyl alcohol from other components of the solution for preparation It does not. For example, the film forming conditions of the flat membrane constituting the membrane may be varied, or the membrane may be subjected to a surface treatment for separation so that the organic matter such as polyvinyl alcohol is separated from the other components of the preparation solution.

More specifically, a functional coating film or a surface layer capable of determining the permeability of a substance depending on a difference in the repulsive force of the ionic charge on the film (for example, controlling the internal pore size of the film inner membrane) A treatment film may be formed to separate organic materials such as polyvinyl alcohol from other components of the preparation solution.

It is preferable to use a membrane capable of setting a plurality of separation standards (for example, molecular weight and ionic charge repelling force) capable of separating organic components such as polyvinyl alcohol and other components of the preparation solution.

The preparation solution may be introduced into the membrane from the buffer tank through suitable means. For example, a transfer device such as a pump can be used so that the solution for preparation can be introduced into the membrane at a constant pressure.

The polyvinyl alcohol-containing fraction mainly contains polyvinyl alcohol, but may contain a small amount of active ingredients for the preparation solution (iodine, potassium iodide, boric acid, etc.) depending on the performance of the membrane or the composition of the pre-purification solution. Since the amount of the active ingredient in the fraction is reduced by repeating the membrane separation step by refluxing, repeating the membrane inflow step can increase the recovery rate of the effective ingredient.

Further, as the amount of the preparation solution collected through the membrane increases through the reflux and concentration process of the fraction containing polyvinyl alcohol and the like, the composition ratio of the effective ingredients becomes larger than that of the unused manufacturing solution Lt; / RTI > solution). To this end, at least one concentration selected from the group consisting of iodine, potassium iodide and boric acid may be monitored.

Regarding the waste treatment, it is also possible to reduce the amount of waste to be discharged because the polyvinyl alcohols and the like are concentrated in the buffer tank by repeating the step of introducing the waste into the film.

The method for removing polyvinyl alcohol foreign matter according to the present invention includes a step of putting a purified preparation solution (a solution for preparation in which a fraction containing polyvinyl alcohol or the like is removed) into a production facility and reusing it for producing a polarizer.

According to the method for removing foreign matters of polyvinyl alcohol of the present invention, the purified preparation solution has almost no difference in composition ratio from the original production solution. For example, there may be a difference of less than 10% between the two. In addition, the fraction containing polyvinyl alcohol or the like may be repeatedly refluxed and concentrated so that the difference in the component ratio can be substantially reduced.

According to the method for removing foreign matter of polyvinyl alcohol according to the present invention, the purified preparation solution can be adjusted so that the composition ratio and the temperature of the solution are substantially the same as the original preparation solution before being put into the manufacturing facility. For example, the temperature difference between both may be less than 10%.

In order to finely adjust the concentration and temperature of the purified preparation solution, the purified preparation solution permeated through the membrane may be collected in a certain storage tank and then introduced into the production facility. In transferring the purified manufacturing solution from the storage tank to the manufacturing facility, a transfer means such as a pump may be used.

The fraction containing polyvinyl alcohol may be discharged collectively for disposal or may be separately discharged for controlling the concentration of polyvinyl alcohol. When the fraction containing polyvinyl alcohol is refluxed and introduced into the membrane again, if the concentration of the polyvinyl alcohol flowing into the membrane is too high, the membrane may be damaged, shortening the lifetime or reducing the recoverability of the active ingredient. For example, the concentration of the preferred concentrated polyvinyl alcohol is 10 to 100,000 ppm.

The disposal of the fraction containing polyvinyl alcohol can be suitably carried out according to the operating conditions of the purification process, for example, it can be carried out from several days to several weeks.

The polyvinyl alcohol foreign matter removal method of the present invention may further include a filtering process for removing the foreign matter that may be included in the transfer of the preparation solution and the treatment process before each step as needed. For example, prior to introducing the production solution containing polyvinyl alcohol into the separation membrane, the filtrate is passed through a filter having a pore size of 0.1-10 μm according to the size of the foreign material, And the foreign matter generated during the injection process can be removed through the safety filter having a pore diameter of 0.1-10 탆 according to the size of the foreign object before the purified manufacturing solution is introduced into the manufacturing facility.

Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples are merely illustrative examples of the present invention, and the scope of the present invention should not be construed as being limited to the following examples.

Example

<Reuse Process of Cleaning Solution>

As shown in FIG. 1, a system in which the reuse method of the present invention is implemented is operated.

A cleaning solution containing potassium iodide and boric acid was fed from the cleaning bath to the buffer tank. And the cleaning solution is supplied from one time to several times according to the treatment target amount.

The temperature adjusting unit is adopted so that the temperature of the cleaning solution supplied to the film is different from the temperature of the solution in the solution tank by less than 30 占 폚. As the temperature control unit, a heating line in a buffer tank, a tank jacket or a heat exchanger was used.

Before the cleaning solution was supplied to the membrane, the solution for preparation was filtered using a filter having a pore size of 0.1 mu m to several mu m to remove foreign matter generated during the supply of the solution for preparation, and the stability of the solution for preparation of the treatment was secured.

The RO membrane (reverse osmosis membrane) was used as the membrane in the separation step.

In order to discharge the cleaning solution through the separation step, the waste liquid discharge line together with the reflux line is configured to enable disposal without stopping the system.

The main operating conditions of this embodiment are shown in Table 1 below.

Transmission flux (m ³ / hr) membrane
Transmittance
(%) Movable pressure
(kg _f / cm ²⁾ driving
Temperature
(° C) Membrane specification Feed Reject Permeate Return available
Membrane area (m ² ) module
size
(inch) module
Quantity 5 4 One 0.0083 20 50 10 ~
40 37.4 8 6

FIG. 2 shows changes in the concentration of potassium iodide that is concentrated according to the number of reflux cycles (re-charge degree), and FIG. 3 shows the change in the concentration of boric acid. Referring to FIG. 3, it can be seen that the recovery rate of boric acid in the sixth order is remarkably increased.

< PVA  Foreign material removing process>

As shown in FIG. 4, the purification system implementing the purification method of the present invention was operated.

The purification system is applied to the dyeing and crosslinking process to feed the production solution containing polyvinyl alcohol from the solution tank of the mass production site to the buffer tank of the purification site. And the manufacturing solution is supplied from one time to several times according to the treatment target amount.

A temperature control unit was employed so that the temperature of the production solution supplied to the membrane was controlled within 3 ° C of the solution temperature of the solution tank. As the temperature control unit, a heating line in a buffer tank, a tank jacket or a heat exchanger was used.

Before the solution for preparation was supplied to the membrane, the solution for preparation was filtered using a filter having a pore size of 0.1 mu m to several mu m to remove the foreign matter generated during the supply of the solution for preparation, and the stability of the solution for preparation of the solution was secured.

In the purification step, the preparation solution was filtered with a few inches of the membrane that did not pass the molecular weight of 300 or more, and the fraction that did not pass through the membrane was recycled to the buffer tank. The purified preparation solution passed through the membrane was collected in a storage tank.

A temperature control unit similar to that in the buffer tank was also installed in the storage tank to minimize the temperature difference between the solution for mass production of the solution tank and the solution for the treatment of the storage tank, and was then reintroduced into the solution tank. In addition, a safety filter having a pore size of several micrometers or less was provided in the line reintroduced into the solution tank from the storage tank to secure the stability of the solution for preparation after purification.

In order to discharge the polyvinyl alcohol separated, the waste liquid discharge line together with the reflux line is constructed so that the waste can be continuously discharged without stopping the system.

The main operating conditions of this embodiment are shown in Table 1 below.

Transmission flux (LPM) membrane
Transmittance
(%) Movable pressure
(kg _f / cm ²⁾ driving
Temperature
(° C) Membrane specification Feed Reject Permeate Drain available
Membrane area (m ² ) module
size
(inch) module
Quantity 16 12.5 3.3 0.2 20% 3 25
-55 7.9 4 3

FIG. 5 shows changes in the concentration of polyvinyl alcohol (PVA) and total organic carbon contained in the thus-prepared preparation solution with time. The results are shown in Table 5. In the purification solution before and after purification by the purification system of this Example, The concentrations of iodine, potassium iodide, and boric acid contained in each of these are shown in FIGS. 6 to 8, and the recovery rates of these iodine, potassium iodide, and boric acid are shown in FIG.

The total organic carbon was measured using a TOC-V CPH model from SHIMADZU.

The recovery rates of the active ingredients (iodine, potassium iodide and boric acid) were calculated as the ratio of the content of each component in the solution for preparation in the storage tank collected after purification to the content of each component in the solution tank in the solution tank.

In FIG. 5, the preparation solution (chemical solution) of the buffer tank in the purification system and the polyvinyl alcohol (PVA) of the solution for solution preparation (chemical solution) in the purification system are treated at a rate of 1000 L / day or 2000 L / The loss and its loss were confirmed by analyzing the concentrations of the active ingredients.

As shown in FIG. 6, iodine was initially lost due to dyeing of the membrane, but after 20 days, the loss of iodine was remarkably reduced from about 50% at the initial stage to about 25% at 20 days. For more than 20 days, iodine was expected to produce less than 10% loss and to be recovered for longer periods of operation. For the remaining potassium iodide and boric acid, only a loss of less than 10% in the test period of this example was recorded.

Claims (27)

Introducing a polarizer preliminarily removed from a polyvinyl alcohol foreign object into a water washing equipment in a polarizer manufacturing facility;
Recovering a cleaning solution containing potassium iodide and boric acid in the washing facility and storing the cleaning solution in a first buffer tank;
Introducing the stored cleaning solution into a membrane having a selective permeability according to molecular weight and charge to separate the potassium iodide and boric acid-containing fractions from the cleaning solution; And
Introducing said fraction into at least one of a dyeing facility and a crosslinking facility installed in a line on which a film is impregnated and reusing it for producing a polarizer;
Of the cleaning solution for polarizer production.
The method of claim 1, further comprising refluxing the fraction to the first buffer tank and then flowing it into the membrane to concentrate the potassium iodide and boric acid in the fraction.
3. The method of claim 1, further comprising concentrating the separated fraction so that the concentration of potassium iodide in the fraction is less than 10% of the potassium iodide in the manufacturing solution in the polarizer manufacturing facility. Line reuse method.
The method of claim 1, further comprising adjusting the temperature of the fraction to less than 10% of the temperature of the manufacturing solution in the manufacturing facility.
The in-line recycling method of a cleaning solution for polarizer production according to claim 1 or 2, further comprising discharging the fraction to discard the separated cleaning solution.
The method of claim 5, wherein the fraction is stored in a second buffer tank prior to discharging the separated cleaning solution, and the stored cleaning solution is introduced into a membrane having a selective permeability according to molecular weight and charge to remove the potassium iodide Further comprising separating the boric acid-containing fraction and transferring it to the first buffer tank. The method for in-line recycling of a cleaning solution for polarizer production according to claim 1,
3. The method of claim 1, further comprising monitoring the concentration of potassium iodide and boric acid in the fraction after separating the fraction.
The in-line recycling method of a cleaning solution for polarizer production according to claim 1, further comprising the step of passing a filter having a pore size of 0.1 to 10 mu m prior to introducing the cleaning solution into the membrane.
The in-line recycling method according to claim 1, wherein the wash water facility is a water bath provided in a line or a wash tank for circulating and supplying a wash water solution to the water bath.
delete delete The method according to claim 1, wherein the step of removing the polyvinyl alcohol foreign matter comprises:
Recovering a preparation solution containing polyvinyl alcohol as a foreign substance in the polarizer manufacturing facility and storing the recovered solution in a buffer tank;
Introducing the stored preparation solution into a membrane having selective permeability according to molecular weight to separate the polyvinyl alcohol-containing fraction from the preparation solution; And
Adding the manufacturing solution from which the fraction has been removed to the manufacturing facility and reusing it for polarizer production;
Of the cleaning solution for polarizer production.
13. The method of claim 12, further comprising refluxing the fraction to the buffer tank and then flowing it into the membrane to concentrate the polyvinyl alcohol in the fraction.
The cleaning solution for polarizer production according to claim 12, further comprising the step of concentrating the fraction-removed solution for preparation such that the composition ratio of the fraction of the preparation solution from which the fraction is removed is less than 10% In-line reuse method.
13. The in-line recycling method of a cleaning solution for polarizer manufacturing according to claim 12, further comprising the step of adjusting the temperature of the manufacturing solution from which the fraction is removed to a difference of less than 10% with the temperature of the manufacturing solution in the manufacturing facility.
14. The method of claim 12 or claim 13, further comprising discharging the fraction for discarding.
13. The in-line recycling method of claim 12, wherein the preparation solution from which the fraction is removed is a solution for dyeing, a solution for crosslinking, or both.
18. The in-line recycling method of a cleaning solution for preparing a polarizer according to claim 17, wherein the preparation solution from which the fraction is removed contains at least one selected from the group consisting of iodine, potassium iodide, and boric acid.
19. The method of claim 18, further comprising monitoring at least one concentration selected from the group consisting of iodine, potassium iodide, and boric acid prior to reusing the preparation solution from which the fraction has been removed, Way.
13. The method of claim 12, further comprising the step of passing a filter having a pore size of 0.1 - 10 [mu] m before introducing the manufacturing solution into the membrane.
delete The in-line recycling method of a cleaning solution for polarizer production according to claim 12, wherein the film does not transmit a molecular weight of 300 or more.
13. The in-line recycling method of a cleaning solution for polarizer production according to claim 12, wherein the membrane further has a selective permeability according to an ionic charge repulsion force.
14. The in-line recycling method according to claim 13, wherein the concentration of the concentrated polyvinyl alcohol is 10 to 100,000 ppm.
15. The manufacturing solution according to claim 14, wherein the preparation solution from which the fraction is removed has an in-line of a cleaning solution for polarizer production comprising 0.001 to 0.1 mol / L of iodine, 0.001 to 15% by weight of potassium iodide, or 0.001 to 8% Reuse method.
16. The in-line recycling method of a cleaning solution for producing a polarizer according to claim 15, wherein the production solution from which the fraction is removed has a temperature of 20 to 60 ° C.
13. The method of claim 12, further comprising passing a safety filter having a pore size of 0.1 - 10 [mu] m prior to introducing the manufacturing solution into which the fraction has been removed, into the manufacturing facility.

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