KR20090010880A - Method and apparatus for utilizing a circulation of a process solution of polarizing film - Google Patents

Abstract

A cycle use system of the polaroid film manufacture drug solution is provided to reduce industrial waste and to reduce raw material cost by mixing iodination potassium concentrate with iodine and being adjusted a solution for dyeing and again being supplied to a dye bath etc. A cycle use system(1) of the polaroid film manufacture drug solution comprises a waste water reservoir(14), an electrodialytic unit(16) and a recycle process part. The waste water reservoir stores waste water from a bath. A PVA(polyvinyl alcohol) film(2) manufacturing the polaroid film is dipped into a solution including iodine and iodination potassium. The electrodialytic unit controls a pH of the waste water stored in the waste water reservoir to 7 or less and separates iodine ingredient in the waste water by an electrodialysis method as an iodination potassium concentrate.

Description

METHODS AND APPARATUS FOR UTILIZING A CIRCULATION OF A PROCESS SOLUTION OF POLARIZING FILM}

The present invention relates to a circulating use method and system of a polarizing film-producing chemical liquid which circulates and uses raw materials of iodine and boron from waste liquid generated when producing an iodine polarizing film or the like.

As a polarizing film used for a liquid crystal display etc., the polyvinyl alcohol-type film (PVA film) which adsorbed and oriented iodine is generally known. Among such polarizing films, an iodine-based polarizing film is usually produced by immersing a PVA film in which iodine is adsorbed and orientated in an aqueous solution containing boric acid. In this manufacturing process, a waste liquid containing iodine ions, boric acid, potassium ions, water-soluble organic substances, and the like is generated. Such manufactured waste liquid is generally treated by industrial flocculation by reducing the specific component contained therein by a flocculation method, adsorption method, ion exchange method, filtration method, or the like below the value defined in the drainage standard, and then discharging or concentrating it as industrial waste water. It is becoming.

However, in recent years, the drainage standard has become much stricter, and it is difficult to reduce the boron concentration in the wastewater below the reference value in conventional treatment methods such as flocculation, adsorption, ion exchange and filtration. In addition, emission reduction is desired for industrial waste in view of disposal costs and environmental issues.

In addition, if boron and iodine can be efficiently recovered from these wastewaters, and this can be circulated and used as a raw material for producing a polarizing film, it is also possible to reduce industrial waste and reduce raw material costs.

In general, in order to recover iodine and boron from the wastewater and recycle it, it is necessary to concentrate the production waste thereof.

In the conventionally disclosed method for treating a polarizing plate manufacturing waste liquid (see Patent Document 1, for example), the waste liquid discharged by the polarizing plate manufacturing process is electrodialyzed, and a concentrated liquid mainly containing an organic component and a desalting liquid mainly containing an inorganic component. Was separated.

By the way, it is not only possible to process such a polarizing plate manufacturing waste liquid, but also to recycle it as a raw material, so that it is possible to reduce raw material cost and disposal cost, and to build an environmentally friendly manufacturing system by reducing industrial waste. It becomes possible.

However, the above-described conventional techniques have been developed mainly for the treatment of the waste liquid, and no studies have been made on the technique for circulating and using the iodine and boron separated and recovered with high efficiency, and the detailed conditions for the circulating use.

 [Patent Document 1] Japanese Unexamined Patent Publication No. 2001-314864

Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method and a system for circulating use of a polarizing film manufacturing chemical which can circulate and use a manufacturing chemical with high efficiency from the waste liquid generated when producing a polarizing film. do.

In order to solve the above-mentioned problems, the circulating use system of the polarizing film production chemical solution to which the present invention is applied is dyed for immersing a PVA (polyvinyl alcohol) film for producing a polarizing film in a dyeing solution containing iodine and potassium iodide. An electrodialysis apparatus for storing the waste liquid from the bath and adjusting the pH of the waste liquid stored in the waste liquid reservoir to be less than 7, and then separating the iodine component in the waste liquid as potassium iodide concentrate by electrodialysis. And a recycling processing unit for adjusting the dyeing solution by adding and mixing new iodine to the potassium iodide concentrate from the electrodialysis apparatus and supplying it to the dyeing bath.

The present invention provides a pH adjustment step of adjusting a waste solution from a dye bath for immersing a PVA (polyvinyl alcohol) film for producing a polarizing film in a dyeing solution containing iodine and potassium iodide so as to have a pH of 7 or less; A separation step of separating the iodine component in the waste solution as a potassium iodide concentrate by electrodialysis, and a recycling step of adjusting the dyeing solution by adding and mixing new iodine to the potassium iodide concentrate and supplying it to the dye bath. By mixing the potassium iodide concentrate with iodine, it is adjusted as a dyeing solution and supplied again to a dye bath, so that a so-called recycling system can be constructed. Therefore, it becomes possible to reduce raw material cost while reducing industrial waste.

EMBODIMENT OF THE INVENTION Hereinafter, the best form for implementing this invention is demonstrated in detail with reference to attached drawing.

1 shows a configuration of a circulating use system 1 of a polarizing film production chemical according to the present invention. The circulation use system 1 of this polarizing film manufacturing chemical | medical solution is used for the dyeing bath 11 and the dyeing bath 11 for immersing the PVA (polyvinyl alcohol) film 2 for manufacturing the polarizing film 2. About the manufacturing line 20 which consists of the crosslinking bath 12 for immersing the PVA film 2a after being immersed, and the washing bath 13 for washing the PVA film 2b immersed in the crosslinking bath 12 The array is installed. This circulation use system 1 includes a waste liquid storage tank 14 for temporarily storing waste liquids from the dyeing bath 11, the cross-linking bath 12, and the washing bath, and the waste liquid supplied from the waste liquid storage tank 14. The activated carbon tank 15, the electrodialysis apparatus 16 to which the waste liquid which passed this activated carbon tank 15 are supplied, and the electrodialysis apparatus 17 to which the desalination liquid from this electrodialysis apparatus 16 are supplied are provided. Doing.

The PVA film 2 is a film obtained by forming a film of these resins containing polyvinyl alcohol, ethylene-vinyl acetate copolymer saponification, or a small amount of other copolymerization components. As other polymer components, for example, unsaturated carboxylic acid, olefin, unsaturated sulfonic acid, or the like may be applied.

The polymerization degree of PVA resin is 1000-10000 normally, Preferably it is 1500-5000.

The saponification degree of PVA resin is about 85-100 mol% normally, Preferably it is about 98-100 mol%.

The PVA film 2 may be applied to any method of forming a PVA resin into a film. Although the film thickness of this polarizing film 2 is not specifically limited, For example, it is about 30 micrometers-150 micrometers.

The PVA film is sufficiently swollen in water and then dyed in the dye bath 11.

The dye bath 11 contains a dyeing solution containing iodine and potassium iodide. The composition of the dyeing solution is, for example, a weight ratio of water: iodine: potassium iodide of 100: 0.01 to 0.5: 0.1 to 10. By immersing the PVA film 2 in the dyeing solution of such a weight composition, it becomes possible to set it as the PVA film 2a which adsorbed iodine on the surface. It is preferable to make the temperature of this dyeing bath 11 into 20-50 degreeC normally.

The crosslinking bath 12 contains a solution for crosslinking containing boric acid and potassium iodide. The composition of the solution for crosslinking is, for example, a weight ratio of water: boric acid: potassium iodide of 100: 1.0 to 7.0: 1.0 to 8.0. By immersing the PVA film 2 in the crosslinking solution which consists of such a weight composition, it becomes possible to set it as the PVA film 2b which the polymer of iodine bridge | crosslinked and stabilized on the surface of the PVA film 2a. In addition, it is preferable that the temperature of this crosslinking bath 12 shall be 40 degreeC or more, More preferably, it is 50 degreeC-85 degreeC. Moreover, although the immersion time of the PVA film 2 by this crosslinking solution is not specifically limited, For example, it is 10 to 1200 second, Preferably it is about 30 to 600 second.

The washing bath 13 is filled with washing water. By immersing the PVA film 2b from the crosslinking bath 12 in this washing bath 13, it becomes possible to remove the impurity etc. which adhered to the surface. Then, a polarizing film is manufactured from the PVA film 2 through a drying process.

In the process of being immersed in these dyeing baths 11-13, this PVA film 2 is extended | stretched. The ratio of the final length of the stretched PVA film 2 to the initial length of the unstretched PVA film 2 is usually 3 to 7 times, preferably 4 to 6 times.

Moreover, in the process for obtaining a polarizing film, you may make it perform extending | stretching process to the direction orthogonal to the said extending | stretching direction using suitable apparatuses, such as a widening roll and a cross guider.

In addition, the manufacturing process until obtaining a polarizing film from the PVA film 2 mentioned above is not limited to the form mentioned above, You may make it apply any other method.

In addition, you may paste a protective film on one side or both surfaces of the polarizing film obtained as mentioned above. Here, a protective film is added for the purpose of the improvement of water resistance, handleability, etc. of a polarizing film, and the transparent material suitable for the formation can be used. In particular, plastics excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and the like are preferably used. Examples thereof include thermoplastic resins such as polyester resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins and acrylic resins, acrylic resins, And thermosetting resins such as urethanes, acrylic urethanes, epoxys, and silicones, or ultraviolet curable resins, and the like, and preferred protective films include acetyl cellulose (TAC), and the like, and polyolefin resins include novo as amorphous polyolefin resins. And resins having a polymerized unit of a cyclic polyolefin such as a linen or polycyclic norbornene-based monomer. In addition, the transparent protective film used for a protective layer may be the thing which performed the hard coating treatment, an anti-reflective process, the treatment for the prevention of sticking, the diffusion, an antiglare, etc., etc., unless the objective of this invention is impaired.

Moreover, although the adhesion treatment of a polarizing film and a protective film is not specifically limited, For example, the adhesive agent which consists of vinyl alcohol type polymers, or the adhesive agent which consists of water-soluble crosslinking agents of vinyl alcohol type polymers, such as boric acid, borax, glutaraldehyde, melamine, and oxalic acid, It can carry out through solvent-type adhesive agents, such as epoxy type, polyester type, and vinyl acetate with favorable transparency, or adhesive resin which can be hardened by polymerization reaction, such as acrylic polymerization resin and a urethane resin.

In addition, the waste liquid from each of these baths 11-13 is gathered in each waste bath, or it collects in the waste liquid storage tank 14. In addition, a facility for concentrating the waste liquid collected in the waste liquid storage tank 14 may be arranged.

The wastewater from this waste liquid storage tank 14 is adjusted to less than pH7 in the pH adjustment process 21. Furthermore, the water-soluble organic compound (TOC) is removed by passing through the activated carbon tank 15. Thereafter, this waste liquid is introduced into the electrodialysis apparatus 16. In addition, the structure of this activated carbon tank 15 can also be abbreviate | omitted. In addition, instead of installing the activated carbon tank 15 at the rear end of the waste liquid storage tank 14, it may be installed at the rear end of the electrodialysis apparatus 17 to remove the TOC.

In the electrodialysis apparatus 16 used in the present invention, a cation exchange membrane and an anion exchange membrane are alternately arranged, for example, between an anode and a cathode, and a plurality of cells are formed by these cation exchange membranes and anion exchange membranes. In this electrodialysis apparatus, when a waste liquid is introduced into a central cell while a direct current is applied between the anode and the cathode, iodine ions (iodine component) and potassium ions in the waste liquid move to the anode side and the cathode side, respectively, and the center cell In cells on both sides of, potassium iodide (KI) is produced. And the aqueous solution (KI concentrate) containing 50-150 g / l of KI, and the desalting liquid in which iodine amount was reduced to 1.0 g / l or less are discharge | emitted from the electrodialysis apparatus 16. As shown in FIG.

At this time, if the pH of the waste liquid introduced into the electrodialysis apparatus 16 exceeds 7, the coexisting boric acid (H ₃ BO ₃ ) is dissociated to increase the amount of boric acid ions. It is incorporated. On the other hand, when the pH of the waste liquid is less than 7, since most of the boric acid is present as a molecule without dissociation, the boric acid is discharged in the desalting liquid as it is, even when electrodialysis is carried out. As a result, boron and iodine in the waste liquid can be efficiently separated.

2 is a diagram showing the pH on the horizontal axis, and the concentration of boric acid (H ₃ BO ₃ ) relative to the vertical axis showing the relationship between the pH of the solution and the form of boron. Under the condition that the pH of the solution is less than 7, most of the boric acid is present as boric acid molecules without dissociation. Therefore, the pH of the waste liquid to be added to the electrodialysis apparatus 16 is less than 7. Accordingly, since dissociation of boric acid can be suppressed, boric acid is discharged as it is without moving even when electrodialysis is performed, and the amount of iodine can be reduced without changing the amount of boron in the waste liquid.

In addition, when the waste liquid is acidic, free iodine is generated, the ion exchange membrane may deteriorate, and the efficiency of electrodialysis may decrease, so that the pH of the waste liquid is preferably 3 or more. Thereby, generation | occurrence | production of free iodine by air oxidation of iodine ion can also be suppressed. Alternatively, the redox potential may be controlled by a reducing agent such as potassium sulfite such that free iodine is not produced. In such a case, it is possible to prevent the mixing of sulfate ions with the KI concentrate by using a selective membrane capable of moving only monovalent ions in the anion exchange membrane.

The KI concentrate thus obtained is adjusted as a dyeing solution by adding and mixing new iodine and supplied to the dyeing bath 11 again. In addition, this KI concentrate is adjusted as a solution for crosslinking by adding and mixing new boric acid, and can be reused again as a preparation chemical in the crosslinking bath 12. In this way, it is possible to construct a so-called recycling system in which the KI concentrate is separated from the waste liquid and used again as a manufacturing chemical liquid. Therefore, it is also possible to reduce raw material costs while reducing industrial waste.

The KI concentrate can be recycled to any one of a dyeing solution and a crosslinking solution.

Further, the desalting liquid containing boric acid (H ₃ BO ₃ ) and organic matter separated from the electrodialysis apparatus 16 is added to alkali pH hydroxide, such as NaOH and KOH, more preferably KOH, to the pH adjustment step 23. In this case, the pH is adjusted to 7 or more, preferably 9 or more, and then introduced into the electrodialysis apparatus 17. In this electrodialysis apparatus 17, boron is isolate | separated and the aqueous solution (boric acid concentrate) containing about 100-500 g / liter of NaB (OH) ₄ and KB (OH) ₄ can be isolate | separated. In order to circulate and reuse the boric acid concentrate as a crosslinking solution, free alkali is removed, and in the pH adjustment step 23, boric acid having a pH of 4 to 7 is preferably used. The alkali may be removed, and the like may be adjusted as a solution for iodine crosslinking to be supplied to the crosslinking bath 12 again. In addition, as the acid for pH adjustment in this pH adjustment process 23, hydroiodic acid is preferable. Accordingly, in the present invention, the recycling of not only the KI concentrate but also the boric acid concentrate can be realized. In addition, when recycling this boric acid concentrate, the potassium iodide solution mixed with this can be made to use the produced | generated KI concentrate.

Moreover, in the above-mentioned embodiment, the manufacturing line 20 which arranged the dyeing bath 11, the crosslinking bath 12, and the washing bath 13 in order in the circulation use system 1 to which this invention was applied to the last. Although the installation case has been described, the configuration is not limited thereto. The circulation use system 1 to which the present invention is applied may be applied to any production line in which a bath for immersing a PVA film exists.

The bath for immersing the PVA film is injected with any one of a solution containing iodine and potassium iodide, a solution containing boric acid and potassium iodide, a solution containing only potassium iodide, a solution containing iodine and potassium iodide and boric acid have.

The waste liquid from the bath is stored in the waste liquid reservoir 14 to obtain a boric acid concentrate and / or potassium iodide concentrate as in the above-described process. These boric acid concentrates and / or potassium iodide concentrates are mixed with each other in some cases, and then sent to the bath, whereby they are recycled.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited by these. In addition, evaluation of the transmittance | permeability and polarization degree shown in the Example was performed as follows.

Transmittance at the time of measuring the obtained polarizing film by one piece Ts and two polarizing films so that the absorption axis direction is the same The transmittance | permeability in parallel position (Tp), and the absorption axis orthogonal to two polarizing films The transmittance | permeability in case of foaming was made into orthogonal transmittance (Tc).

The transmittance | permeability T calculated | required the spectral transmittance ((tau) (lambda)) for every predetermined | prescribed wavelength space | interval d (lambda here) in the wavelength range of 380-780 nm, and was computed by following formula (1). In the formula, Pλ represents the spectral distribution of standard light (C light source), and yλ represents a two-degree field of view orange function.

식 (1)

Formula (1)

Spectral transmittance (?) Was measured using a spectrophotometer ("U-4100" manufactured by Hitachi). The polarization degree Py was calculated | required by following formula (2) from the parallel phase transmittance Tp and the quadrature transmittance Tc.

Py = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100 Equation (2)

The color was obtained by a *, b * of the Commission for International Illumination (Commission Internationale de l'Eclairage, abbreviated CIE) based on JIS Z 8729.

<Example 1>

Iodine amount 16g / liter, boron amount 5.4g / liter, potassium amount 4.9g / liter, TOC 0.01g / liter and pH pH 5.2, 5.7 liters of the waste liquid for polarizing film production was electrodialysis apparatus S3)) was used as a concentrate, 1 liter of water, and dialyzed for 3 hours at a constant voltage of 10V. In addition, the membrane area in this electrodialysis apparatus is 0.055 m <^2> . ACS-8T (manufactured by Astom Co., Ltd.) was used as the anion exchange membrane, and K501-SB (manufactured by Astom Co., Ltd.) was used as the cation exchange membrane. As a result, the concentrate after electrodialysis had an iodine amount of 87 g / liter, a boron amount of 1.0 g / liter, potassium of 26.7 g / liter, TOC of 0 g / liter, an iodine migration rate of 94%, and a boron migration rate of 1.9%. In addition, the desalting liquid had an iodine amount of 1.0 g / liter, a boron amount of 5.3 g / liter, a potassium amount of 0.3 g / liter, and a TOC of 0.01 g / liter.

<Example 2>

48 liters of desalting solution (iodine amount 1.0g / liter, boron amount 5.3g / liter, potassium amount 0.3g / liter, TOC 0.01g / liter, pH 5.2) after moving iodine in Example 1 0.026 liters of% KOH aqueous solution was added, and the pH was adjusted to 11 using an electrodialysis apparatus (Asizer A3, manufactured by Astom, Inc.), using 0.2 liters of water as a concentrate, and dialyzing at a constant voltage of 10 V for 3 hours. It was done. AHA (manufactured by Astom Corporation) and CMB (manufactured by Astom Corporation) were used as the anion exchange membrane. As a result, the concentrate after electrodialysis had an iodine concentration of 4.75 g / liter and a boron concentration of 25 g / liter. The boron migration rate was 94%. In the desalting solution, the amount of iodine was 0.05 g / liter, the boron concentration was 0.3 g / liter, and the TOC was 0.01 g / liter.

<Example 3>

The PVA (polyvinyl alcohol) film (Gurereza brand name: VF-PS) whose saponification degree is 99% or more and 2400 degree of average polymerization degree was immersed for 2 minutes in 30 degreeC warm water, and swelling process was carried out. The swelling-treated film was diluted with water at 0.1% iodine (manufactured by Junsei Chemical Co., Ltd.) and 11.4% of potassium iodide recovered in Example 1 by diluting with water and immersed in a dye bath adjusted to 1.0% at 30 ° C for 3 minutes to perform dyeing treatment. It was.

The film obtained by dyeing was mixed with 14.3% of boric acid recovered in Example 2 with a boric acid concentrate adjusted to pH 4-7 with a 57% hydrochloric acid solution, and a 11.4% potassium iodide concentrate from Example 1, followed by mixing with water. In the crosslinking bath which diluted, the boric acid concentration was 4%, and the potassium iodide concentration was adjusted to 5%, it immersed at 50 degreeC for 3 minutes, and the extending | stretching process was performed by 5 times the magnification. Furthermore, the polarizing film was obtained by wash | cleaning the film extended | stretched in a crosslinking bath for 30 second in the washing bath which put washing water of 30 degreeC, and drying for 2 minutes at 70 degreeC after washing process. The polarizing film obtained by drying and the triacetyl cellulose film (trade name: TD-80U manufactured by Fuji-Shashin Film Co., Ltd.) which were treated with alkali were laminated using the polyvinyl alcohol-type adhesive agent, and the polarizing plate was obtained.

<Example 4>

Hereinafter, as a comparative example 1, the PVA (polyvinyl alcohol) film (Gurereza brand name: VF-PS) whose saponification degree is 99% or more and 2400 degree of average polymerization degree was immersed in 30 degreeC warm water for 2 minutes, and swelling process was carried out. The film which swelled was immersed for 3 minutes at 30 degreeC in the dyeing bath adjusted to 0.1% of iodine (made by Junsei Chemical Co., Ltd.) and 1.0% of potassium iodide (made by Junsei Chemical Corporation). The film obtained by dyeing was extended | stretched by 5 times magnification for 3 minutes in the 50 degreeC crosslinking bath adjusted to 4% of boric acid (made by Societa Chimica Larderello s.p.a.) and 5% of potassium iodide (made by Junsei Chemical Co., Ltd.).

The polarized film was obtained by wash | cleaning the film extended | stretched in a crosslinking bath for 30 second in the washing bath which put washing water of 30 degreeC, and drying for 2 minutes at 70 degreeC after washing process.

Used iodine, potassium iodide, and boric acid were all industrial reagents, and the processing conditions were the same conditions as Example 1, and the polarizing film was produced.

The polarizing film obtained by drying and the alkali-treated triacetyl cellulose film (Fuji Shashin Film company make brand name: TD-80U) were laminated using the polyvinyl alcohol-type adhesive agent, and the polarizing plate was obtained.

Table 1 shows the results of measuring optical characteristics of the polarizing plates obtained in Example 3 and Comparative Example 1 by using a spectrophotometer.

S, p, and c in a table | surface represent the single, parallel, orthogonal | vertical position of a polarizing plate, respectively.

The polarizing plates obtained in Example 3 and Comparative Example 1 were cut to a size of 40 × 40 mm, and an endurance test was performed.

In the durability test, a polarizing plate was placed in a tester having a dry heat atmosphere of 95 ° C., a wet heat atmosphere of 65 ° C., and a relative humidity of 95%, and compared with the amount of change in the single transmittance (Ts) and the degree of polarization (Py) before the test and after 506 hours.

The test results are shown in Tables 2 and 3.

As apparent from the above Examples, Comparative Examples, and Tables 1, 2, and 3, a polarized film was recovered using a circulating use system of a polarizing film preparation chemical liquid from a waste liquid containing iodine and potassium iodide and boric acid. It was confirmed that a good polarizing film with optical properties and durability could be prepared using aqueous potassium iodide solution and concentrated boric acid solution.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the circulation use system of the polarizing film manufacturing chemical liquid to which this invention is applied.

Figure 2 shows the pH on the horizontal axis and the concentration of boric acid (H ₃ BO ₃ ) compared to the vertical axis showing the relationship between the pH of the solution and the form of boron.

<Description of the code>

One… Raw material recycling system,

2… Polarizing film,

11... Dyeing Bath,

12... Crosslinking Bath,

13... Cleaning Bath,

14... Waste fluid reservoir,

15... Activated Carbon,

16, 17... Electric dialysis device,

20... Manufacturing line

Claims (6)

A waste liquid storage tank for storing waste liquid from a bath for immersing a PVA (polyvinyl alcohol) film for producing a polarizing film in a solution containing iodine and potassium iodide, An electrodialysis apparatus for adjusting the pH of the waste liquid stored in the waste liquid storage tank to be less than 7 and thereafter separating the iodine component in the waste liquid as a potassium iodide concentrate by electrodialysis; The recycling use system of the polarizing film manufacturing chemical | medical agent characterized by including the recycling process part which adjusts the said solution by adding and mixing a new iodine component with the said potassium iodide concentrate from the said electrodialysis apparatus, and supplies it to the said bath. A waste liquid storage tank for storing waste liquid from a bath for immersing a PVA (polyvinyl alcohol) film for producing a polarizing film in a solution containing boric acid and potassium iodide, An electrodialysis apparatus for adjusting the pH of the waste liquid stored in the waste liquid storage tank to be less than 7 and thereafter separating the iodine component in the waste liquid as a potassium iodide concentrate by electrodialysis; In the electrodialysis apparatus, the desalting liquid from which iodine is separated from the waste liquid is adjusted to have a pH of 7 or more, preferably 9 or more, and thereafter, boron for separating the boron component in the desalting solution as a boric acid concentrate by electrodialysis. Separation and concentration unit, The boric acid concentrate from the electrodialysis apparatus is adjusted to have a pH of less than 7, the potassium iodide concentrate is mixed, the solution is adjusted by adding fresh potassium iodide and boric acid, and this is supplied to the bath. System for circulating use of chemical liquid for manufacturing polarizing film. A waste liquid storage tank for storing waste liquid from a bath for immersing a PVA (polyvinyl alcohol) film for producing a polarizing film in a solution containing potassium iodide, An electrodialysis apparatus for adjusting the pH of the waste liquid stored in the waste liquid storage tank to be less than 7 and thereafter separating the iodine component in the waste liquid as a potassium iodide concentrate by electrodialysis; And a recycling treatment section for adjusting the solution by further mixing fresh potassium iodide with the potassium iodide concentrate from the electrodialysis apparatus and supplying it to the bath. A waste liquid storage tank for storing waste liquid from a bath for immersing a PVA (polyvinyl alcohol) film for producing a polarizing film in a solution containing iodine and potassium iodide and boric acid, An electrodialysis apparatus for adjusting the pH of the waste liquid stored in the waste liquid storage tank to be less than 7 and thereafter separating the iodine component in the waste liquid as a potassium iodide concentrate by electrodialysis; In the electrodialysis apparatus, after adjusting the desalting liquid from which iodine is separated from the waste liquid to have a pH of 7 or more, preferably 9 or more, boron separation for separating boron components in the desalting solution as boric acid concentrate by electrodialysis. The concentrating unit, The pH of the potassium iodide concentrate from the electrodialysis apparatus and the boric acid concentrate from the boron separation concentrate is adjusted to be less than 7, and the solution is adjusted by further mixing the potassium iodide concentrate with a new iodine component and boric acid. And a recycling processing unit for supplying this to the bath. Waste solution from the first bath for immersing a PVA (polyvinyl alcohol) film for preparing a polarizing film in a first solution containing iodine and potassium iodide and a PVA film in a second solution containing boric acid and potassium iodide Waste liquid storage tank for storing the waste liquid from the 2nd bath to make, An electrodialysis apparatus for adjusting the pH of the waste liquid stored in the waste liquid storage tank to be less than 7 and thereafter separating the iodine component in the waste liquid as a potassium iodide concentrate by electrodialysis; In the electrodialysis apparatus, after adjusting the desalting liquid which separated the iodine component from the said waste liquid so that pH may be 7 or more, preferably 9 or more, boron which isolate | separates the boron component in the said desalting solution as boric acid concentrate by electrodialysis. Separation and concentration unit, The first solution is adjusted by adding and mixing new iodine components to the potassium iodide concentrate from the electrodialysis apparatus, supplying it to the first bath, and reducing the pH of the boric acid concentrate from the boron separation concentrate to less than 7 Adjusting the second solution by further mixing the potassium iodide concentrate with the new iodine component and boric acid and adjusting the second solution, and supplying it to the second bath. Circular use system. The system of claim 5, wherein the second bath is a bath for immersing the PVA film immersed in the first bath.

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