JPS5889902A - Method for separating liquid mixture - Google Patents

Abstract

PURPOSE:To enhance separation efficiency in separating org. liquid mixture through pervaporation, by using a polymer membrane made by uniformly mixing a fluorine-contg. resin having acid type functional groups with a low mol. wt. polymer not contg. acid type functional groups. CONSTITUTION:A membrane is formed by mixing 100pts.wt. a fluorine-contg. polymer having carboxylic, sulfonic, phosphoric, or phenolic acid groups with 5-100pts.wt. low. mol. wt. polymer of trifluorochloroethylene or copolymer of perfluoroalkyl winyl ether and fluoroolefin. The obtained blended membrane is a nonporous uniform film, and use of this membrane for pervaporation operation permits a mixture of org. liquids to be separated with high separation coefft. and permeation rate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for separating or separating a liquid mixture containing at least an organic liquid as one of its components (hereinafter abbreviated as an organic liquid mixture) by pervaporation using a specific polymer membrane. Concerning the method of concentrating.

A process for separating organic liquid mixtures using non-porous, uniform polymeric membranes has been previously described in U.S. Pat. No. 29,535.
No. 02 Specification. In this separation process, the liquid to be treated is generally supplied to the primary side (high pressure side) of the polymer membrane, and the easily permeable substance is transferred to the secondary side (low pressure side). This is a method of preferentially transmitting it as vapor. This membrane separation method is used to separate liquid mixtures that could not be separated using conventional simple methods, such as azeotropic mixtures, mixtures with close boiling points and low relative volatility, and mixtures containing substances that polymerize or modify when heated. It is attracting attention as a new method of concentration.

Conventionally, the polymer membranes used in such separation methods are polyethylene and polypropylene.

Cellulose polymer materials, polyacrylonitrile, polyamide, polyester, polystyrene.

Membranes made of polytetrafluoroethylene or copolymers thereof are known. However, when such a membrane is used to separate an organic liquid mixture by pervaporation, the following practical difficulties are observed. That is, (1) Since the concentration ratio (separation coefficient 'AB) of the organic liquid heated substance passing through the polymer membrane once is small, it takes a very large number of times to concentrate or separate it to the desired concentration. must pass through the membrane. Generally, the separation factor 'AB is as follows.

(2) Since the amount of permeation of an organic liquid mixture through a polymer membrane (generally expressed as the permeation amount per unit membrane surface area, unit membrane thickness, and unit time) is small, the membrane surface area must be made very large or The thickness of the molecular membrane must be made extremely thin. Therefore, in the former case, the equipment cost becomes excessive, and in the latter case, problems arise in the strength and durability of M.

As the above-mentioned improved process, a method using a polymer membrane in which sulfonic acid groups etc. are bonded to a polymer base, a method using a specific polyamide membrane, a method using an ionomer polymer membrane, etc. are disclosed in Japanese Patent Application Publication No. It is disclosed in Japanese Patent No. 52-111888, Japanese Publication No. 52-111889, Japanese Publication No. 54-33278, Japanese Publication No. 54-33279, etc.

The present inventor has conducted various studies on means for separating or concentrating various organic liquid mixtures by pervaporation.
As a result of repeated investigations, we came to the following extremely interesting findings. That is, CJ, CI or Cx F4 /C
F* (FOCs F+ and other polymers room temperature to 100℃
When a wax-like solid low-molecular weight material is blended into a fluororesin membrane having acid-type functional groups such as carboxylic acid groups or sulfonic acid groups, internal plasticization occurs within the membrane and toughness can be imparted. be. It has also been found that the above-mentioned difficulties can be smoothly and advantageously overcome by using such a blend film for paper lamination.

The present invention has been completed based on the above findings, and it is possible to prepare a liquid mixture containing at least an organic liquid as one of its constituents by using a fluorine-containing tree containing no acid-type functional groups. The present invention provides a novel method for separating a liquid mixture, which is characterized in that separation is performed by pervaporation using a polymer membrane formed by uniformly mixing solid low-molecular-weight polymers.

In the present invention, it is important to form a film by uniformly mixing a specific solid low-molecular-weight substance into a fluorine-containing tal exchanger having an acid type functional group (hereinafter referred to as fluorine-containing ion exchange tatitt?). The mixing ratio of the solid low molecular weight substance is not particularly limited, but is usually selected from a range of 5 to 100 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the fluorine-containing ion exchange fat. If the mixing ratio of the solid low molecular weight material is too small, the reinforcing effect such as toughness in the present invention will be slight, and if it is too large, the fluorine-containing resin having functional groups will not be used as the polymer membrane material. At the same time, the reinforcing effect may also decrease and be destroyed. It is preferable that the optimum mixing ratio be selected depending on the type of the fluorine-containing ion-exchanged fat, the solid low molecular weight substance, or a combination thereof.

Therefore, the solid low molecular weight material in the present invention has a temperature ranging from room temperature to 10
It is important that the material exhibits a solid form such as a waxy state at about 0° C., and that it has a relatively low molecular weight. That is, the molecular weight of the solid low molecular weight substance is usually 500
- About 30,000, preferably 1,000 to io, o
Selected from a range of about oo. If the molecular weight is too low, for example in the form of liquid or oil, it will be disadvantageous in terms of reinforcing effect, and it will be difficult to stabilize the effect over a long period of time due to round numbers. However, the effect of imparting toughness is small, and as mentioned above, there are difficulties in terms of film performance.

There is no particular reason to limit the type of specific low molecular weight polymer used in the present invention as long as it is as described above. It is desirable to select For example, low molecular weight copolymers of ethylene trifluoride, perfluoroalkyl vinyl ethers such as perfluoromethyl vinyl ether and perfluoropropyl vinyl ether, and fluoroolefins such as ethylene tetrafluoride and ethylene trifluorochloride are used. Polymers, low molecular weight copolymers of tetrafluoroethylene, etc., and hexafluoropropylene, octafluorobutene, etc. can be mentioned. In addition, low molecular weight polymers with excellent corrosion resistance and thermal stability, such as hexafluoropropylene/epoxide and tetrafluoroethylene epoxide, may also be used.

In the present invention, the fluorine-containing ion exchange resin is preferably a resin made of a fluorine-containing polymer having an ion exchange group such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, or a thunol hydroxyl group.

Such resins include, for example, tetrafluoroethylene,
chlorotrifluoroethylene natonohynyl monomer,
Fluorovinyl containing ion exchange groups such as sulfonic acid, carboxylic acid, and phosphoric acid groups.

In particular, it is preferable to use polymers having the following structures (a) and (b).

(Il (CF, -cxx'→+, (0)
+cp+ -cx +where X is F, CI, H or -CFm, and X' is X or CFm (CFt+m, m is 1 to 5, and Y is selected from the following nine).

-(cps)A, -o-fcv*fA, (
0-CF-CFkA.

X+y+! - both are 0 to 10, and Z.

Ri is selected from -F or a perfluoroalkyl group having 1 to 10 carbon atoms. Moreover, A is -COOH.

-coo・-! -M, -5OIH, -5, etc., or -50. which can be converted to these groups by hydrolysis.
F, -CN.

-COF, -COOR', -5o,R', -
CONR'R', -5 is an acid type functional group such as NR'R', M is a metal atom such as an alkali metal or alkaline earth metal, or -NR'R'R'R', an atom of lFiM valence, R' is an alkyl group having 1 to 20 carbon atoms, and R*, R3, R4, R@.

R. and R1 represent a hydrogen atom or R'.

Therefore, in the present invention, the fluorine-containing ion exchange resin (hereinafter abbreviated as acid type fluororesin) is composed of a fluorinated ethylenically unsaturated monomer (1) and an acid type functional group. Quantity (n)
It can be a copolymer with (1) is tetrafluoroethylene.

Examples include chlorotrifluoroenalene, propylene hexafluoride, ethylene trifluoride, vinylidene fluoride, vinyl fluoride, and preferably fluorine represented by the general formula CFI -CXX' (X and X' are as described above). It is an olefin compound. Among these, perfluoroolefin compounds are preferred, and tetrafluoroethylene is particularly preferred. (Ill is preferably a fluorovinyl compound of the general formula CF, =CXY (X and Y are as defined above), and preferred examples include CF, dicx-(ocptcpRl), -(o), −(
cpR'1) r-A (here, p is 0 to 5. q is 0 to
Examples include fluorovinyl compounds represented by the following formula: it r is an integer of 0 to 12, X, R,, A are as described above, and a/ is R. From the point of view of performance and availability, X is a fluorine atom, and Rf is -CFs +
R'f is a fluorine atom, p is 0 to 1. q is 0 to 1 + r is 0
It is preferable that it is 8. fluorovinyl compounds (preferable representative examples include CFm ""CFO
(CFs) 1++s C0OR'.

CFm = CFO (CFt), ~8COF.

CFI=CF(CFt). ~8COOR'ICF!
=CFOCF Snow CF (CFs) OCF Goose CFICOO
R'.

CFm ”'CFOCF*CF(CFs)OCF*C
F*COF.

CFm “CFO (CF Otori), ~8so, p lCFm
””CFOCFxcF (CFs)QCFxCF2
Examples include 80s F.

In addition, in the present invention, functional groups other than carboxylic acid type,
For example, reduction treatment of fluorinated copolymers having sulfonic acid type functional groups (JP-A-52-24175, JP-A-52-241)
76, No. 52-24177, etc.), oxidation treatment (JP-A No. 53-132094, No. 53-132069)
A polymer obtained by converting a sulfonic acid type functional group into a carboxylic acid type functional group may be used as a specific acid type fluorine group. Of course, the carboxylic acid type may be converted to the sulfo/acid type, or the acid type functional monomer may be converted to the carboxylic acid type or sulfonic acid type as described above by the same treatment at the monomer stage. (You can also use it as a river.

Furthermore, in the present invention, two or more of each of (1) and (Ill) or (a) and (b) above may be used as the structural unit of a specific acid type fluororesin. In addition, other components such as olefin compounds such as ethylene, propylene, isobutylene, CFj=
cvroo (o is carbon number 1 - fluorovinyl ether, CFs ""CF-CF=CF*.

Divinyl monomers such as CFs=CFO (CF), ~40CF=CF, and others can also be used singly or in combination of two or more.

In the present invention, the content t of the acid type functional group in the acid type fluorinated resin can be adopted over a wide range, and is selected from a wide range of 0.01 to 6 milliequivalents/g dry resin in terms of ion exchange capacity.

The ion exchange capacity is preferably about 0.1 to 22 meq/g dry resin. In addition, from the viewpoint of mechanical strength as a polymer membrane, the molecular weight of the specific acid type fluorine resin is preferably 50°C or higher, preferably about 70 to 300°C, when expressed as the TQ value described below. It is.

In this specification, the term r TQ J is defined as follows. That is, the temperature at which the volumetric flow rate 10C1+j/sec, which is related to the molecular weight of the polymer, is defined as To. In this case, the volume flow rate was determined by using a polymer with an acid type functional group of methyl ester type such as -COOCHs group, and applying the polymer under a pressure of 30 kg/cd at a constant temperature.

The amount of polymer melted and flowed out from an orifice having a length of 2 i+i+ is expressed in units of 1/sec. t
The ``ion exchange capacity'' was calculated as follows. That is, a specific acid-type fluororesin whose acid-type functional group is H-type, such as -COOH, is left in 1N HCI at 60°C for 5 hours to completely convert it to H-type, so that no HCI remains. Washed thoroughly with water. Then, add 0.5 g of H-type resin here to I
], and was left standing at room temperature for 2 days in a solution prepared by adding 25 ml of water to 25 ml of 1N NaOH. The resin is then taken out and the amount of NaOH in the solution is determined by back titration with 0.1N MCI.

In the present invention, the solid low molecular weight substance and acid type fluorine,
1 fat is uniformly mixed and a film is formed. The blend membrane thus obtained does not necessarily need to be formed from one type of polymer, nor does it need to have only one type of acid type functional group.

For example, two types of polymers may be used together as the ion exchange material, or a blend membrane may be used in which a weakly acidic functional group such as a carboxylic acid group and a strongly acidic functional group such as a sulfonic acid group are used together. For film formation, various conventionally known methods can be employed. However, such specific blend membranes are still necessary.
Non-woven fabrics, metal sheets, porous materials, etc. can be used for reinforcement.

In the present invention, uniform mixing of the specific low molecular weight substance and the fluorine-containing ion exchange resin and film formation are carried out by various means as described above. For example, homogeneous mixing with specific low molecular weight substances can be carried out using an aqueous dispersion, an organic solution, or an organic dispersion of a fluorine-containing ion exchange resin, or a specific low molecular weight substance can be mixed with a specific low molecular weight substance in a wet process. It is also possible to form a film from a solution, organic dispersion, etc. by a casting method. Of course, it is also possible to form a film by employing a tri-blend method or by heat-melting a blended product. In the latter case, when forming a film by hot melt molding, the fluorine-containing ion exchange + @ fat should be in the form of an appropriate ion exchange group that does not cause decomposition of the ion exchange group it has, for example, an acid or ester in the case of a carboxylic acid group. It is preferable to do it in a mold,
In the case of a sulfonic acid group, it is preferable to use the -5O1F type. Furthermore, the blend may be heated and melt-molded to form pellets, and the pellets may be formed into a film by extrusion molding, press molding, or the like.

The above-mentioned blend membrane used in the present invention is a polymer membrane formed by uniformly mixing a specific low molecular weight substance with acid type fluorine TATLW, and is a non-porous uniform membrane with a thickness of 1 to 1. A thickness of about 250 microns, preferably from 5 to 180 microns is adopted.1 If the film thickness becomes too thin, the film will lack strength or durability. Moreover, if the film thickness is relatively thick, the permeation of the liquid mixture becomes small, making it impractical. The shape of the polymer membrane is usually a flat membrane, but other shapes such as a cylindrical or hollow fiber shape can be used to increase the surface area and embed a reinforcing material, or the membrane can be formed on a porous reinforcement. Various reinforcing means such as lamination may be applied.

The method of the present invention is carried out using the above-mentioned specific acid type fluororesin using an apparatus partitioned into a secondary chamber and a secondary chamber. −
The next chamber contains the organic liquid mixture to be separated or concentrated in liquid form, while the two chambers are reduced in pressure by appropriate methods or circulated with other liquids or gases. In this way,
The organic liquid mixture is passed through a polymer membrane and separated or concentrated by pervaporation. - The liquid inside the next chamber is preferably circulated externally or internally, or - agitated by providing a suitable stirring device inside the next chamber. The specific polymer membrane is held in a suitable manner to partition the primary chamber and the secondary chamber, but it is advantageous in terms of durability if it is supported by, for example, a perforated reinforcing plate. - Substances that permeate the polymer membrane from the next chamber are taken out from the second chamber and collected. It is usually desirable to appropriately heat the secondary chamber and/or the secondary chamber using a suitable heating device, such as a heating jacket.

The separation method of the present invention is practical under a wide range of temperatures, typically (1 to 200' C1, preferably room temperature to 10
It is selected from a range of about 0°C.

If the temperature is too high, there will be problems in maintaining the shape of the polymer membrane, and if the temperature is too low, the amount of liquid permeated will be small. Generally, the amount of permeation can be increased at high temperatures, but the concentration ratio (separation coefficient) due to membrane permeation becomes smaller. In addition, the pressure range that can be adopted is normally vacuum to 100ky/clt,
Preferably, the pressure is from vacuum to about 50 to 9/cd; if the pressure is too high, it becomes difficult to maintain the shape of the polymer membrane.

The organic liquid mixtures that can be separated by the method of the present invention include various combinations, such as mixtures of organic substances that cannot be separated by normal distillation methods because of the presence of azeotropic points, and mixtures of organic substances that cannot be separated by ordinary distillation methods because their boiling points are close to each other. This method is particularly effective in the case of mixtures of organic substances that are difficult to separate by distillation.

Further, the organic liquid mixture may be entirely dissolved in each other uniformly, or a part of the organic liquid mixture may exceed the solubility and precipitate into a suspended state.

However, the organic liquid mixture needs to be in a liquid state in its mixed state within the above-mentioned implementation temperature range and at normal pressure or within the employed pressure range.

Examples of such organic liquid mixtures include benzene/cyclohexane and benzene/n as mixtures having an azeotropic point.
- mixtures of organic substances such as hexane, methanol/acetone, benzene/methanol, acetone/chloro, form; water/isopropanol, water/ethanol/l/
, water/n-furohanol, water/allyl alcohol,
Water/2-methoxyethanol, water/isobutanol.

Water/alcohol mixtures such as water/n-butanol, water/2-butanol, water/furfuryl alcohol, water/n-pentanol, water/2-pentanol, water/4-methyl-1-furinol; water/ Tetrahydrofuran, water/
Examples include water/organic solvent mixtures such as dioxane/water/methyl ethyl ketone.

Mixtures whose boiling points are close to each other include ethylbenzene/styrene and p-chloroethylbenzene/
p-Chlorstyrene, toluene/methylcyclohexane, butadiene/butenes, butadiene/butanes, n-
Examples include butene/mebutene. Other examples include water/glycerin, water/glycols, water/propylene chlorohydrin, */7'' robin dichlorohydrin, water/epichlorohydrin, water/hydrazine, and mixtures of isomers.

Furthermore, the method of the present invention can be applied to these mixtures not only in two-component systems as described above, but also in multi-component systems, such as ternary or more component systems. Of course, the method of the invention can also be applied to mixtures containing organic and inorganic substances, such as wastewater containing organic liquids.

The closer the mixing ratio of the liquid mixture to be treated is to an equivalent mixture, the higher the concentration ratio becomes. If the desired purity cannot be obtained by passing through a polymer membrane once (-membrane concentration), the organic liquid mixture may be concentrated or separated to the desired degree by passing through a similar device multiple times (multi-stage concentration). You can also.

Examples of the present invention will be described in more detail below, but it goes without saying that the present invention is not limited by the above description.

Example 1 Using C, FWCOON as an emulsifier, NHa)*St
C5Fa and CFa =CFO(CF
m ) m C00CHs is copolymerized and the ion exchange capacity is 1
．． A copolymer having a meq/f of 44 was obtained. To this copolymer, 20%
It was added in an amount of % by weight and thoroughly kneaded with a mixing roll. The film was then press-formed at 200°C to form a film with a thickness of 100μ, which was then hydrolyzed with caustic soda and diluted with pure water at 90°C.
After being treated at 70°C for 16 hours, it was dried at 70°C for 24 hours.

Using the obtained membrane, a mixed solution of water and inpropatol (isopropatol/water 82/18. weight ratio) was separated by vane extraction. Temperature: 40°C, permeation side power: 10" At wmHg, the separation coefficient of improvised water with respect to C-nol was 196, and the permeation rate was 483 f/m1·hr.

Example 2 C@Fe C00NHh as emulsifier (Nua)s
C5Fa and CFs = CFOC using stos as an initiator
A wax-like low molecular weight product was obtained by copolymerizing sFt at room temperature to 100°C.

This is the same mountain C as in Example 1 and CFt ””CF O (C
Fm) It was added to a copolymer of acO*cH* at a concentration of 20% by weight, and thoroughly kneaded with a mixing roll. Next, it was press-formed at 200° C. to form a film with a thickness of 100 μm.

After the film was hydrolyzed in caustic soda, the functional groups were changed to -COOH type in hydrochloric acid, treated in pure water at 90°C for 16 hours, and dried at 70°C for 24 hours. Using the obtained experiment, a mixture of water and ethanol (ethanol-non-water = 9476, weight ratio) was separated using a refrigerator. The separation factor for ethanol was 5.21 and the permeation rate was 935 f/m''hr.

Procedural Amendment (Paper) April 1980 Director-General of the Patent Office Haruki Shimada 1, Indication of the case 1986 Patent Application No. 186828 2, Name of the invention Method for separating liquid mixtures 3, Person making the amendment Case and Relationship Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (
004) Asahi Glass Co., Ltd. 6. Number of inventions increased by amendment None 7. Subject of amendment Specification

Claims (1)

[Claims] A film is formed by uniformly mixing a solid low-molecular-weight polymer that does not contain an acid-type functional group with a fluorine-containing resin having an acid-type functional group from a liquid mixture containing at least an organic liquid as one of its constituent components. 1. A method for separating a liquid mixture, the method comprising separating a liquid mixture using a pervaporage method using a polymer membrane.