JP4478996B2

JP4478996B2 - Treatment method of polarizing plate manufacturing waste liquid

Info

Publication number: JP4478996B2
Application number: JP2000134909A
Authority: JP
Inventors: 寿子新明; 雅博川端; 剛根本; 洋井上
Original assignee: Organo Corp
Current assignee: Organo Corp
Priority date: 2000-05-08
Filing date: 2000-05-08
Publication date: 2010-06-09
Anticipated expiration: 2020-05-08
Also published as: JP2001314864A

Description

【０００１】
【発明の属する技術分野】
本発明は、液晶ディスプレイ等に用いられる偏光板の製造工程等で発生する廃液の処理方法に関するものである。
【０００２】
【従来の技術】
液晶ディスプレイ製造に用いられる偏光板製造工程では、一般的に、ポリビニールアルコールのフィルムを先ず沃素を溶かし込んだ沃化カリウム水溶液に浸し、沃素をポリビニールアルコールの中に充分吸い込ませた後、硼酸の水溶液の中に移し替え、その中でフィルムを一方向に引っ張って偏光フィルムを作る。この偏光フィルムに保護フィルムを付けて、偏光板を製造する。
【０００３】
この偏光板製造工程で排出される偏光板製造廃液は、従来は、水酸化ナトリウム等のアルカリで凝集後、液を蒸発法で濃縮して減容化し、廃棄処分されている。
【０００４】
【発明が解決しようとする課題】
しかし、この従来方法で処理すると、蒸発法による濃縮時にグリセリン（ポリビニールアルコールの可塑剤）を主成分とする有機物類と硼素分や沃素分等の無機物類が錯体等の化合物を形成し、液の粘性が過度に増大して処理が困難になるばかりか、冷えて固まると濃縮装置に付着して除去困難な状態となり、処理不能となる。これを改善するために、珪藻土等を添加すると粘性を抑えることができるが、これにより廃棄物量が増大してしまう。
【０００５】
また、有機物類を取り除く方法としては生物処理による方法が考えられるが、偏光板製造廃液中に含まれる有毒な硼素分や沃素分等の無機物類（硼酸や沃化物等）の高濃度が微生物に悪影響し、生物処理は困難である。
【０００６】
本発明の目的は、上述の様な従来方法の欠点を解消し、廃棄物量を減少させ得る偏光板製造廃液の処理方法を提供することである。
【０００７】
【課題を解決するための手段】
本発明者等は、上記目的を達成する為に鋭意研究を重ねた結果、偏光板製造廃液のｐＨをアルカリ側にせずにそのまま電気透析することにより、該廃液に含有されるグリセリンを主成分とする有機物と、硼素分や沃素分等からなる無機物成分とを分離できることを見出し、本発明を完成するに至った。ここで、偏光板製造廃液中では、硼素分は硼酸として、沃素分は分子の形でも存在すると考えられるが、その殆どは酸や塩の形で存在すると考えられる。
【０００８】
即ち、本発明は、偏光板製造工程より排出される廃液を電気透析し、有機物成分を主に含む脱塩液と無機物成分を主に含む濃縮液とに分離することを特徴とする偏光板製造廃液の処理方法を提供するものである。
【０００９】
本発明方法により処理される偏光板製造廃液（以下、時に「廃液」と言う）において、通常は、有機物成分はグリセリンやポリビニールアルコール等であるのが一般的で、一方、無機物成分は、電気透析中はその殆どが硼素や沃素の無機化合物類であって、水素イオン、カリウムイオン、硼酸イオン、沃化物イオン、次亜沃素酸イオン等の無機イオン類に解離していると考えられる。
【００１０】
本発明の処理方法に用いる電気透析装置は、一般的に使用されているものを用いることができる。図１に本発明の処理方法の原理を示す。陰極１と陽極２の間には、カチオン交換膜３とアニオン交換膜４が交互に並べられて複数のセルを構成している。セルに送られた廃液中の無機物成分である硼素分や沃素分等の無機物類は、イオンに解離しているため、陰極１と陽極２に直流電流が印加されると、これらのイオン類は、陽イオンであればカチオン交換膜３を通って陰極側に移動するが次のアニオン交換膜で実質的に阻止され、陰イオンであればアニオン交換膜４を通って陽極側に移動するが次のカチオン交換膜で実質的に阻止される。即ち、アニオン交換膜４を陽極１に面した側に持つセル（Ａ）は濃縮セルとして機能し、ここでは無機イオン類が濃縮されて濃縮液となり、アニオン交換膜４を陰極２に面した側に持つセル（Ｂ）は脱塩セルとして機能し、ここでは無機イオン類が減少して脱塩液となる。廃液中の有機物成分である有機化合物類はイオン交換膜を殆ど通らないため濃縮液と脱塩液中にほぼそのまま残留する。なお、ここで、無機イオン類としては、水素イオン、カリウムイオン等の陽イオン類と、硼酸イオン、沃化物イオン、次亜沃素酸イオン等の陰イオン類が廃液に含まれると考えられる。
【００１１】
上述の説明で明らかな様に、図１に示した様に脱塩セル及び濃縮セルの両方に廃液を通液した場合は、濃縮液中にも有機化合物類が残留することとなるが、濃縮セルでは無機イオン類のみが濃縮されるのであって有機化合物類は濃縮されないので、濃縮液中の有機化合物類濃度は廃液中の濃度と実質的に同じであり、この点において、有機化合物類、無機物類が同時に濃縮されてしまう蒸発法とは明らかに相違し、また、得られる脱塩液は、有毒な無機物類が少なくなっているので、生物処理が可能となる。
【００１２】
また、廃液を脱塩セルに通液し、濃縮セルには純水を通水する様な方式で本発明の方法を実施することもできる。この場合は、得られる濃縮液中に有機物成分が含まれるとしても極微量なので、錯体等の化合物の形成は殆ど無く、濃縮液は蒸発により容易に濃縮減容化でき、従来方法の欠点を解消することができる。
【００１３】
本発明の処理方法で用いる電気透析装置に使用されるイオン交換膜は、陽イオンと陰イオンを選択的に分離できるものであれば特に限定されない。また、イオン交換膜の性能も一般的なもので良く、例えば、厚さは０．１〜０．６ｍｍ、抵抗は１〜１０Ω・ｃｍ^２程度のものであれば良い。
【００１４】
また、本発明の処理方法に用いる電気透析装置の構造は限定されるものではなく、例えば、カチオン交換膜とアニオン交換膜とを、脱塩される液の流入孔及び流出孔、濃縮される液の流入孔及び流出孔が設けられているガスケットで適当な間隔を保って交互に複数積層して複数のセルを構成し、両端を一組の電極で挟んだもので、一組の電極の間に入れる膜対の数は、通常は１０〜１００である。
【００１５】
本発明方法により濃縮分離された沃素分や硼素分等の無機物類を主成分とする濃縮液は、偏光板製造工程中で再利用する為の原料として用いることもできる。例えば、イオンクロマトグラフィー法や硼素選択性イオン交換樹脂処理法等の適当な処理方法により、この濃縮液を沃素分を主として含む液と硼素分を主として含む液とに分離し、それぞれに必要に応じて新たに沃素や沃化カリウム、硼酸等を加えてそれぞれの無機成分濃度を調整して、偏光板製造用液として再利用することが可能である。
【００１６】
【発明の実施の形態】
次に、図２を参照しつつ、発明の実施の形態を説明するが、本発明はこれに限定されるものではない。図２は、本発明の処理方法を実施する為の装置を示す概略フロー図である。なお、図２中でＰはポンプを表す。
【００１７】
廃液槽６に貯留された廃液を脱塩液槽７に送り、ここから電気透析装置５に送り、また、濃縮液槽８中の純水を電気透析装置５に送り、電気透析を開始する。なお、純水の代りに廃液を濃縮液槽８から電気透析装置５に送って電気透析を開始してもよいことは、図１について説明したことから理解できるであろう。
【００１８】
脱塩液と濃縮液をそれぞれ脱塩液槽７と濃縮液槽８から電気透析装置５を通し、それぞれ脱塩液槽７と濃縮液槽８に戻すことを繰り返す様に循環させる循環処理方式で電気透析を行うことができ、電気伝導度計Ｃで脱塩液中の無機イオン濃度を監視し、所望の値に到達した時点で脱塩液槽７から脱塩液を排出させ、必要に応じて生物処理等に供し、一方、濃縮液は濃縮液槽８から排出させ、蒸発法により濃縮減容化したり、例えば、上述の様な適当な処理方法により、沃素分を主とする無機成分を含む液と硼素分を主とする無機成分を含む液とに分離し、それぞれの無機成分濃度を調整し、偏光板製造用液として再利用することもできる。廃液槽６と脱塩液槽７の間のポンプＰと電気伝導度計Ｃは点線で表される制御用配線で繋がれており、次の電気透析の為の廃液を廃液槽６から脱塩液槽７へ送る信号を該制御用配線を通して送信することができる。
【００１９】
また、電気透析を連続処理方式で行うこともでき、その際は脱塩液中の無機イオン濃度を所望の値に維持する様に、廃液槽６から脱塩液槽７へのライン（配管）中のポンプＰの開度を電気伝導度計Ｃの信号値で点線で表される制御用配線を経由して自動制御してもよい。
【００２０】
また、図２では１個の電気透析装置を用いているが、複数の電気透析装置を用いて多段処理方式で電気透析を行ってもよい。
【００２１】
【実施例】
以下、本発明を実施例により詳細に説明するが、本発明は実施例に限定されるものではない。
【００２２】
実施例１
図２について説明した様な循環処理方式（濃縮液槽８には、最初、純水を供給）により、グリセリン、ポリビニールアルコール、硼素分（硼酸等）、沃素分（沃化物等）を含有する偏光板製造工程で排出される廃液を処理した。使用した電気透析装置の性能を表１に示す。表１中の両イオン交換膜は、旭化成工業株式会社製である。
【００２３】
【表１】

【００２４】
表１に示した能力を持つ電気透析装置を用いて廃液を処理した結果、廃液は、表２に示すような濃縮液と脱塩液に分離された。なお、有機物成分は、ＴＯＣ（全有機体炭素）濃度で測定した。なお、表２中でＬはリットルを表す。
【００２５】
【表２】

【００２６】
表２の結果から、脱塩液中にはＴＯＣ成分がほぼそのまま残存しており、無機物類である硼素分（硼酸等）、沃素（沃化物等）は脱塩されて濃縮液中に移行したことが分かる。
【００２７】
従って、有機物類と無機物類は分離され、個別に処理することが可能となる。脱塩液側に残る有機物類は生物処理等を行うことができ、また、無機物類の濃縮液については蒸発法により濃縮減容化後廃棄処分することや、更に上述の様な処理を行って偏光板製造工程中で再利用することも可能となる。
【００２８】
【発明の効果】
本発明の処理方法は、偏光板製造廃液を効率良く処理し、廃棄物量を減少させることができる。また、回収された沃素分や硼素分等の無機成分は、例えば、イオンクロマトグラフィー法や硼素選択性イオン交換樹脂処理法等の適当な処理方法により分離し、偏光板製造用液を調製するのに有効に再利用することもできる。
【図面の簡単な説明】
【図１】図１は、本発明の処理方法の原理を示す概略説明図である。
【図２】図２は、本発明の処理方法を実施する為の装置を示す概略フロー図である。
【符号の説明】
１陰極
２陽極
３カチオン交換膜
４アニオン交換膜
Ａ濃縮セル
Ｂ脱塩セル
５電気透析装置
６廃液槽
７脱塩液槽
８濃縮液槽
Ｃ電気伝導度計
Ｐポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating a waste liquid generated in a manufacturing process or the like of a polarizing plate used for a liquid crystal display or the like.
[0002]
[Prior art]
In a polarizing plate manufacturing process used for manufacturing a liquid crystal display, generally, a polyvinyl alcohol film is first immersed in an aqueous potassium iodide solution in which iodine is dissolved, and iodine is sufficiently absorbed into the polyvinyl alcohol. In the aqueous solution, the film is pulled in one direction to make a polarizing film. A polarizing plate is produced by attaching a protective film to the polarizing film.
[0003]
Conventionally, the polarizing plate manufacturing waste liquid discharged in this polarizing plate manufacturing process is agglomerated with an alkali such as sodium hydroxide, and then the liquid is concentrated by evaporation to reduce the volume and discarded.
[0004]
[Problems to be solved by the invention]
However, when this conventional method is used, organic substances mainly composed of glycerin (polyvinyl alcohol plasticizer) and inorganic substances such as boron and iodine form a compound such as a complex when concentrated by evaporation. Not only does the viscosity increase excessively, the treatment becomes difficult, but when it cools and hardens, it adheres to the concentrator and becomes difficult to remove, making the treatment impossible. In order to improve this, when diatomaceous earth etc. are added, viscosity can be suppressed, but this will increase the amount of waste.
[0005]
In addition, biological treatment can be considered as a method for removing organic substances, but high concentrations of inorganic substances (boric acid, iodide, etc.) such as toxic boron and iodine contained in the polarizing plate production waste liquid are present in microorganisms. It is adversely affected and biological treatment is difficult.
[0006]
The objective of this invention is providing the processing method of the polarizing plate manufacture waste liquid which eliminates the fault of the above conventional methods and can reduce a waste amount.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors electrodialyzed the polarizing plate production waste liquid as it is without setting the pH to the alkali side, so that the glycerin contained in the waste liquid is the main component. The present invention has been completed by finding that it is possible to separate an organic substance from an inorganic component composed of boron, iodine, and the like. Here, in the polarizing plate production waste liquid, it is considered that boron is present as boric acid and iodine is present in molecular form, but most of it is considered to exist in the form of acid or salt.
[0008]
That is, the present invention provides a polarizing plate production characterized in that the waste liquid discharged from the polarizing plate production process is electrodialyzed and separated into a desalted liquid mainly containing organic components and a concentrated liquid mainly containing inorganic components. A method for treating a waste liquid is provided.
[0009]
In the polarizing plate production waste liquid (hereinafter sometimes referred to as “waste liquid”) treated by the method of the present invention, the organic component is generally glycerin, polyvinyl alcohol, or the like, while the inorganic component is an electric component. During dialysis, most of them are boron and iodine inorganic compounds, which are considered to be dissociated into inorganic ions such as hydrogen ion, potassium ion, borate ion, iodide ion, hypoiodite ion and the like.
[0010]
As the electrodialysis apparatus used in the treatment method of the present invention, those commonly used can be used. FIG. 1 shows the principle of the processing method of the present invention. Between the cathode 1 and the anode 2, a cation exchange membrane 3 and an anion exchange membrane 4 are alternately arranged to form a plurality of cells. Since inorganic substances such as boron and iodine which are inorganic components in the waste liquid sent to the cell are dissociated into ions, when a direct current is applied to the cathode 1 and the anode 2, these ions are If it is a cation, it moves to the cathode side through the cation exchange membrane 3, but is substantially blocked by the next anion exchange membrane, and if it is an anion, it moves to the anode side through the anion exchange membrane 4. The cation exchange membrane is substantially blocked. That is, the cell (A) having the anion exchange membrane 4 on the side facing the anode 1 functions as a concentration cell. Here, the inorganic ions are concentrated to become a concentrated liquid, and the side on which the anion exchange membrane 4 faces the cathode 2 is concentrated. The cell (B) possessed by the cell functions as a desalting cell, where inorganic ions are reduced to form a desalting solution. Organic compounds, which are organic components in the waste liquid, hardly pass through the ion exchange membrane, and therefore remain almost as they are in the concentrated liquid and the desalted liquid. Here, as the inorganic ions, it is considered that cations such as hydrogen ions and potassium ions and anions such as borate ions, iodide ions and hypoiodite ions are included in the waste liquid.
[0011]
As is clear from the above description, when waste liquid is passed through both the desalting cell and the concentration cell as shown in FIG. 1, organic compounds remain in the concentrated solution. Since only inorganic ions are concentrated in the cell, and organic compounds are not concentrated, the concentration of organic compounds in the concentrated liquid is substantially the same as the concentration in the waste liquid. This is clearly different from the evaporation method in which inorganic substances are concentrated at the same time, and the desalted liquid obtained has fewer toxic inorganic substances, so that biological treatment becomes possible.
[0012]
Further, the method of the present invention can be carried out in such a manner that waste liquid is passed through a desalting cell and pure water is passed through a concentration cell. In this case, even if an organic component is contained in the resulting concentrated liquid, it is extremely small, so there is almost no formation of a compound such as a complex, and the concentrated liquid can be easily concentrated and reduced by evaporation, eliminating the disadvantages of conventional methods. can do.
[0013]
The ion exchange membrane used in the electrodialysis apparatus used in the treatment method of the present invention is not particularly limited as long as it can selectively separate cations and anions. Moreover, the performance of the ion exchange membrane may be general, and for example, the thickness may be 0.1 to 0.6 mm and the resistance is about 1 to 10 Ω · cm ² .
[0014]
Further, the structure of the electrodialysis apparatus used in the treatment method of the present invention is not limited. For example, the cation exchange membrane and the anion exchange membrane are separated from the inflow and outflow holes of the liquid to be desalted and the liquid to be concentrated. A plurality of cells are formed by alternately laminating a plurality of cells at appropriate intervals with a gasket provided with an inflow hole and an outflow hole, and both ends are sandwiched between a pair of electrodes. The number of membrane pairs placed in is usually 10-100.
[0015]
The concentrated liquid mainly composed of inorganic substances such as iodine and boron which are concentrated and separated by the method of the present invention can also be used as a raw material for reuse in the polarizing plate production process. For example, this concentrated liquid is separated into a liquid mainly containing iodine and a liquid mainly containing boron by an appropriate processing method such as an ion chromatography method or a boron-selective ion exchange resin processing method. Then, iodine, potassium iodide, boric acid or the like can be newly added to adjust the concentration of each inorganic component and reused as a polarizing plate production solution.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the invention will be described with reference to FIG. 2, but the present invention is not limited to this. FIG. 2 is a schematic flowchart showing an apparatus for carrying out the processing method of the present invention. In FIG. 2, P represents a pump.
[0017]
The waste liquid stored in the waste liquid tank 6 is sent to the desalting liquid tank 7 and sent from here to the electrodialysis apparatus 5, and the pure water in the concentrated liquid tank 8 is sent to the electrodialysis apparatus 5 to start electrodialysis. It will be understood from the explanation of FIG. 1 that the waste liquid may be sent from the concentrate tank 8 to the electrodialyzer 5 instead of pure water to start electrodialysis.
[0018]
In the circulation processing system, the desalted solution and the concentrated solution are circulated through the electrodialyzer 5 from the desalted solution tank 7 and the concentrated solution tank 8, respectively, and repeatedly returned to the desalted solution tank 7 and the concentrated solution tank 8, respectively. Electrodialysis can be performed, and the inorganic ion concentration in the desalted solution is monitored with the electric conductivity meter C, and when the desired value is reached, the desalted solution is discharged from the desalted solution tank 7, and if necessary On the other hand, the concentrated liquid is discharged from the concentrated liquid tank 8 and concentrated and reduced in volume by an evaporation method. For example, an inorganic component mainly composed of iodine is removed by an appropriate processing method as described above. It can also be separated into a liquid containing and a liquid containing an inorganic component mainly containing boron, and the concentration of each inorganic component can be adjusted and reused as a polarizing plate-producing liquid. The pump P and the electric conductivity meter C between the waste liquid tank 6 and the desalting liquid tank 7 are connected by a control wiring represented by a dotted line, and the waste liquid for the next electrodialysis is desalted from the waste liquid tank 6. A signal to be sent to the liquid tank 7 can be transmitted through the control wiring.
[0019]
In addition, electrodialysis can also be performed in a continuous processing system, and in this case, a line (pipe) from the waste liquid tank 6 to the desalted liquid tank 7 so as to maintain the inorganic ion concentration in the desalted liquid at a desired value. The opening degree of the pump P may be automatically controlled via a control wiring represented by a dotted line with a signal value of the electric conductivity meter C.
[0020]
Moreover, although one electrodialyzer is used in FIG. 2, electrodialysis may be performed by a multistage treatment system using a plurality of electrodialyzers.
[0021]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to an Example.
[0022]
Example 1
2 contains glycerin, polyvinyl alcohol, boron content (boric acid, etc.), iodine content (iodide, etc.) by the circulation processing method as described with reference to FIG. 2 (firstly pure water is supplied to the concentrate tank 8). The waste liquid discharged in the polarizing plate manufacturing process was processed. Table 1 shows the performance of the electrodialyzer used. Both ion exchange membranes in Table 1 are manufactured by Asahi Kasei Corporation.
[0023]
[Table 1]

[0024]
As a result of treating the waste liquid using an electrodialyzer having the ability shown in Table 1, the waste liquid was separated into a concentrated liquid and a desalted liquid as shown in Table 2. The organic component was measured at the TOC (total organic carbon) concentration. In Table 2, L represents liters.
[0025]
[Table 2]

[0026]
From the results shown in Table 2, the TOC component remained almost as it was in the desalted solution, and the inorganic matters such as boron (boric acid, etc.) and iodine (iodide, etc.) were desalted and transferred to the concentrated solution. I understand that.
[0027]
Therefore, organic substances and inorganic substances are separated and can be treated individually. The organic substances remaining on the desalting solution side can be subjected to biological treatment, etc., and the concentrated concentrates of inorganic substances can be disposed of after being concentrated and reduced by evaporation, or further treated as described above. It can be reused in the manufacturing process of the polarizing plate.
[0028]
【The invention's effect】
The treatment method of the present invention can efficiently treat a polarizing plate production waste liquid and reduce the amount of waste. The recovered inorganic components such as iodine and boron are separated by an appropriate treatment method such as an ion chromatography method or a boron selective ion exchange resin treatment method to prepare a polarizing plate production solution. Can be effectively reused.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram showing the principle of a processing method of the present invention.
FIG. 2 is a schematic flowchart showing an apparatus for carrying out the processing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cathode 2 Anode 3 Cation exchange membrane 4 Anion exchange membrane A Concentration cell B Desalination cell 5 Electrodialyzer 6 Waste liquid tank 7 Desalted liquid tank 8 Concentrated liquid tank C Electric conductivity meter P Pump

Claims

A method for treating a polarizing plate manufacturing waste liquid, wherein the waste liquid discharged from the polarizing plate manufacturing process is electrodialyzed and separated into a desalted liquid mainly containing an organic component and a concentrated liquid mainly containing an inorganic component.

The method for treating a polarizing plate production waste liquid according to claim 1, wherein a concentrated liquid mainly containing an inorganic component concentrated and separated by electrodialysis is used as a raw material for reuse in the polarizing plate production process.

The waste, the organic components of glycerin and polyvinyl alcohol, and the processing method of the polarizing plate production waste according to claim 1 or 2, characterized in that contains inorganic components of the boron content and iodine content.