JPS5892412A - Separation of liquid mixture - Google Patents

Abstract

PURPOSE:To effectively separate an org. liquid mixture, by using a high molecular membrane formed from a blended composition comprising fluorine contained polymers having carboxylic acid type functional groups and different ion exchange capacities to carry out pervaporization. CONSTITUTION:A fluorinated olefin monomer such as tetrafluoroethylene and a carboxylic acid type functional monomer such as CF2=CFO(CF2)3COOCH3 are copolymerized to obtain a fluorine contained polymer. Two kinds or more of fluorine contained polymers having different ion exchange capacities are blended by a roller and the blended composition is formed into a film by press molding. The obtained film is hydrolyzed in caustic soda and the hydrolyzed film is treated by pure water and dried to obtain a high molecular membrane. Through this membrane, a liquid mixture containing an org. liquid is permeated to separate or concentrate the org. liquid by pervaporization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing a liquid mixture containing at least an organic liquid as one of its components (hereinafter abbreviated as an organic liquid mixture) by a per-paper resin using a specific polymer membrane. Relating to methods of separating or concentrating - Processes for separating organic liquid mixtures using non-porous homogeneous polymeric membranes have been previously described in U.S. Pat.
This is taught in Specification No. 2, etc. This separation process is generally called a pervaporation process using a membrane.The liquid to be treated is supplied to the primary side (high pressure side) of the polymer membrane, and substances that are easily permeable are transferred to the secondary side (low pressure side). This is a method of preferentially transmitting it as vapor. This separation method is used to separate or concentrate 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 denature when heated. It is attracting attention as a new way to do so.

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 using such a model to separate an organic liquid mixture using a paper resin, the following practical difficulties are observed. That is, (1) The concentration rate (separation coefficient α) of an organic liquid mixture when it passes through a polymer membrane once is small, so in order to concentrate or separate it to the desired concentration, it is necessary to pass through a very large number of It must pass through a membrane. In general, the separation factor α
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 the membrane.

As the above-mentioned improved booths, a method using a polymer membrane in which a sulfonic acid group or the like is bonded to a polymer base, a method using a specific polyamide membrane, a method using an ionomer-based polymer membrane, etc. are disclosed in Japanese Patent Application Laid-open No. It is disclosed in 1982-111888, 1982-111889, 1982-33278, 1982-63279, and the like.

The present inventor has conducted various studies on means for separating or concentrating various organic liquid mixtures by pervaporation.
As a result of repeated studies, it was discovered that a polymer membrane made by blending two or more types of fluororesins with carboxylic acid type functional groups with different ion exchange capacities can smoothly and advantageously overcome the above-mentioned difficulties. .

The present invention has been completed based on the above-mentioned findings, and a liquid mixture containing at least an organic liquid as one of its constituent components is prepared using at least one fluorine-containing polymer having a carboxylic acid type functional group having a different ion exchange capacity. The present invention provides a novel method for separating liquid mixtures, which is characterized by separating liquid mixtures by pervaporation using a polymer membrane made of a blend of two or more types.

According to the present invention, when a polymer membrane is constituted by blending at least two or more fluorinated polymers having different ion exchange capacities, the ion exchange capacity of at least one of the fluorinated polymers is preferably 0. 9 or less, particularly 0.8 or less, and the content of the fluorine-containing polymer having such an ion exchange capacity is preferably equal to or less than the total amount of the fluorine-containing polymer constituting the polymer membrane. It is preferably 50% by weight or less, particularly 40% by weight or less. The content of the fluorine-containing polymer having a low ion exchange capacity is preferably selected from a range of 1% by weight or more, particularly 3% by weight or more.

On the other hand, the fluorine-containing polymer with a high ion-exchange capacity to be blended with the fluorine-containing polymer with a low ion-exchange capacity is adjusted so that the ion-exchange capacity of the polymer membrane falls within the desired range. and the mixing amount is selected. However, too high an ion exchange capacity is disadvantageous in terms of mechanical properties as a polymer membrane, so the upper limit is preferably selected from a range of about 6, particularly 2.2 or less. Thus, by blending the above-mentioned at least two types of fluorine-containing Pi aggregates, the ion exchange capacity after blending can be made to fall within the preferred range described below.

Examples of the fluorine-containing polymer used to produce the polymer membrane in the present invention include a copolymer of a fluorinated olefin monomer and a polymerizable monomer having a carboxylic acid type functional group. obtain. As such copolymers, fluorine-containing polymers having the following structures (a) and (b) are particularly preferred.

(a) ±OF, -0XX' +, (b) ±
at'2-cx±ko\, where X is F, 01. H or -0
Fs, and X' is X or -(OF' t ) m O
F m, m is an integer from 1 to 5, and Y is selected from the following.

Z! (.

Z Rf In the above, both Xe"l and ZU are 0 to 10, and 2 and FL ( are selected from F or a perfluoroalkyl group having 1 to 10 carbon atoms. Also, A is 1000H, -
Coo-TM or -ON, -COF, -00OR' which can be converted into these groups by hydrolysis.

-CON R'R'', M is a metal atom such as an alkali metal or alkaline earth metal, or -NR'R
'R'R', l is the valence number of M, R1 is the number of carbon atoms from 1 to
20 alkyl groups, nG, R$, R4, nG
, am and R7 represent a hydrogen atom or R1.

Accordingly, in the present invention, the fluorine-containing polymer having a carboxylic acid type functional group (hereinafter abbreviated as carboxylic acid type fluororesin) is a fluorinated ethylenically unsaturated monomer (Il).
and a carboxylic acid type functional monomer (II).

(Il is exemplified by tetrafluoroethylene, chlorotrifluoroethylene, propylene hexafluoride, ethylene trifluoride, vinylidene fluoride, vinyl fluoride, etc., and preferably the general formula OF'2=OXX' (X and X' is a fluorinated olefin compound represented by (as described above).Among them, perfluoroolefin compounds are preferred, and tetrafluoroethylene is particularly preferred.(n) is
A fluorovinyl compound of the general formula OF, =OXY (X and Y are as described above) is desirable, and a preferred one is CF 2 =OX (OOF 2 CF ROp
(0) q (OF ROr-A (here, p is O~
6e Q' is O~1. [ is an integer from θ to 12, X,
A fluorovinyl compound represented by Rf and A are as described above, and R1 is Rf is exemplified. From the point of view of performance and availability, X is a fluorine atom, R( is -ci
;'s.

R1 is a fluorine atom, p is θ~1eQ is 0~1°T is O~
Preferably, it is 8. A fluorovinyl compound (a preferred representative example of 1 is 0F2=OFO(O
F2) Rays 0OOR'.

OF2=OFO(CF2)+-sOOF
, OF 2 =OF (OF 2)o-sooOR'
.

CF2 = OFOOF2 C! F(OFs)OOF2
0F2000R'.

OF'2=CFOOF20F(CFs)OOP20F
Examples include 200F.

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 No. 52-24175, No. 52-2417)
6, JP-A-52-24177, etc.), oxidation treatment (JP-A-56-132094, JP-A-53-132069)
A polymer in which a sulfonic acid type functional group is converted to a carboxylic acid type functional group by a method such as 7) may be used as the specific carboxylic acid type fluororesin. Of course,
The monomer may be converted into the carboxylic acid type functional monomer (II) as described above by the same treatment.

Furthermore, in the present invention, the above-mentioned (I), (III) or (A) is used as a structural unit of the carboxylic acid type fluororesin.
It is also possible to use two or more of each of (b) and (b).
In addition to these, other components such as olefin compounds such as ethylene, propylene, and imbutylene, OF
, =OFOQ (Q represents a perfluoroalkyl group having 1 to 10 carbon atoms), fluorovinyl ethers such as CF
2 duck Fl-CF duck F2゜OF 2 =OFO(OF 2
) r~, 0CF=C! divinyl monomers such as F2,
Furthermore, one or more types of other functional monomers having sulfonic acid type functional groups etc. can also be used in combination.

In the case of a copolymer consisting of the polymerized units of (a) and (b) above, the ratios of (a) and (b) above are determined so that each of the (b) units in the copolymer provides the desired ion exchange capacity. The amount of polymerized units can be appropriately controlled by selecting the amount of polymerized units. In addition, the carboxylic acid type fluororesin in the present invention may be a graft copolymer or a block copolymer, but it can be obtained by directly copolymerizing monomers such as (a), (b), (I), and (Ill) above. Particularly preferred are copolymers with uniform dispersibility of functional groups.

When the carboxylic acid type fluororesin of the present invention is produced by a copolymerization reaction as described above, polymerization using peroxy compounds, azo compounds, ultraviolet rays, ionizing radiation, etc. The copolymerization can be carried out by known means under the action of an initiating source. For example, Japanese Patent Publication No. 48-2223, Japanese Patent Publication No. 48-20
Copolymerization can be carried out by methods such as those described in Japanese Patent Publication No. 788, Japanese Patent Publication No. 48-41942, and US Pat. No. 3,282,875. Polymerization methods include bulk polymerization and solution polymerization.

Various polymerization methods such as suspension polymerization and emulsion polymerization can be employed.

In the present invention, the content of the carboxylic acid type functional group in the carboxylic acid type fluororesin can be adopted over a wide range;
In a preferred embodiment, the ion exchange capacity described below is 0.01.
Selected from a wide range of ~6 meq/g dry resin. The ion exchange capacity is preferably 0.1 to 2.
．． Approximately 2 milliequivalents/gram dry resin is employed. In addition, from the viewpoint of mechanical strength as a polymer membrane, the molecular weight of the carboxylic acid type fluororesin is expressed as the TQ value described below.
The temperature is preferably 50°C or higher, preferably about 70 to 300°C.

In this specification, the term rTQJ is defined as follows. That is, the temperature t is defined as TQ, which indicates a volumetric flow rate of 100-1"7 seconds, which is related to the molecular weight of the polymer. Here, the volumetric flow rate is 100 Hz when the carboxylic acid type functional group is used as a polymer. The polymer was filtered at a constant temperature for 1 kg/- under pressure.
The amount of polymer melted and flowed out from an orifice with a length of 2+n is expressed in units of fl''7 seconds.

In addition, "ion exchange capacity" was determined as follows. That is, carboxylic acid type functional group is 1000H group.
The acid type fluororesin was allowed to stand at 60° C. for 5 hours in IN Hot to completely convert to H type, and was thoroughly washed with water so that no ) lot remained.

Then, 0.5 g of this H-type resin was added to 0.5 g of this H-type resin. IN NaO
It was left standing at room temperature for 2 days in a solution of H25- and water 25-. Then, the resin was taken out and the Na0 in the solution was removed.
The amount is determined by back titrating with 0.1N Hot.

When blending two or more types of fluorine-containing polymers having different ion exchange capacities, this can be done using a conventional method.

That is, it is preferably mixed or kneaded using an appropriate roller or Banbury mixer, preferably at a temperature of 50° C. or higher and below the decomposition point of the polymer, usually for 1 minute to 1 hour. .

Subsequently to or together with the blending of the fluorine-containing polymer, the fluorine-containing polymer is formed into a film. As a method for forming such a film, conventionally known or well-known means such as press molding, roll molding, extrusion molding,
Solution casting method, dispersion molding, powder molding, etc. can be adopted. In this case, an olefin polymer such as polyethylene or polypropylene, preferably polytetrafluoroethylene, a copolymer of ethylene and tetrafluoroethylene, or a copolymer of tetrafluoroethylene and hexafluoropropylene is optionally used during film formation. It can be molded by blending a fluorine-containing polymer such as a polymer, or it can be supported on a support made of a cloth, a woven fabric such as a net, a nonwoven fabric, or a porous film made of these polymers. In addition, the weight of the resin that makes up the blend or support is:
It is not included in the above ion exchange capacity value.

In the present invention, when a blend of two or more carboxylic acid-type fluororesins is formed into a polymer film by hot melt molding, etc., the carboxylic acid-type fluororesin is used in such a way that its functional groups do not decompose. It is preferable to use an appropriate functional group form, for example, a carboxylic acid type functional group, an acid type or an ester type.

The polymer film made of carboxylic acid type fluororesin used in the present invention is a non-porous uniform film, and the film thickness is 1 to 25 mm.
0 micron, preferably about 5 to 180 micron. If the film thickness becomes too thin, the film will lack strength or durability. Furthermore, if the membrane is too thick, the amount of permeation of the liquid mixture becomes small, making it impractical. The shape of the polymer membrane is usually a flat membrane, but it can also be used in other shapes such as a cylindrical shape or a hollow fiber shape to increase the surface area. Furthermore, various reinforcing means may be applied, such as embedding a reinforcing material such as a cloth in the membrane, or laminating the membrane on a porous reinforcing body.

The method of the present invention uses the above-mentioned carboxylic acid type fluororesin membrane, -
It is carried out using a device that is divided into a secondary chamber and a secondary chamber.

- The next chamber contains the organic liquid mixture to be separated or concentrated in liquid form, - The pressure in the crab firebox is reduced by an appropriate method, or
or circulating other liquids or gases. In this way, the organic liquid mixture is permeated through the polymer membrane and separated or concentrated by barbage separation. - 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 have permeated the polymer membrane from the next chamber are extracted 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 carried out over a wide range of temperatures, typically from 0 to 200°C, preferably from room temperature to 100°C.
Selected from a range of degrees.

If the temperature is too high, problems will arise 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. Also,
The applicable pressure range is usually vacuum to 100kg/cds
Preferably, the pressure is from vacuum to about 30 ky/-, and 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/chloroform; water/isopropanol, water/ethanol, water/n
-furopanol, water/allylic alcohol, water/2-methoxyethanol, water/isobutanol.

Water/n-butanol, water/2-butanol, water/furfuryl alcohol, water/n-pentanol, water/2-pentanol, water/water such as 4-methyl-1-butanol/
Alcohol-based mixtures 1 Water/organic and vehicle-based mixtures such as water/tetrahydrofuran, water/dioxane, and water/methyl ethyl ketone can be mentioned.

In addition, as mixtures whose boiling points are close to each other, TE, ethylbenzene/styrene, p-chloroethylbenzene/p
-Chlorstyrene, toluene/methyl 7 chlorohexane,
Examples include butadiene/butenes, butadiene/butanes, n-butene/mebutene, and the like. Other examples include water/glycerin, water/glycols, water/propylene chlorohydrin, water/propylene dichlorohydrin, water/epichlorohydrin, water/hydrazine, and isomer mixtures.

Furthermore, the method of the present invention can be applied to these mixtures not only in the above two-component systems but also in multi-component systems, such as ternary or more. 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 temperature volume ratio of the liquid mixture to be treated can be changed within an arbitrary range, but in general, the closer the ratio is to the equal-situation mixture, the higher the concentration ratio will be. If the desired purity cannot be obtained by passing through a polymer membrane once (-membrane concentration), pass it through a similar device multiple times (multi-stage concentration).
It is also possible to concentrate or separate the organic liquid mixture to the desired extent.

Further examples of the present invention are provided below. Although a specific explanation will be given, it goes without saying that the present invention is not limited to this explanation in any way.

Example 1 Tetrafluoroethylene and OF, =OFO(OF,
) 100OOH*, gold, and azobisisobutyronitrile are used as catalysts to copolymerize in bulk, resulting in an ion exchange capacity of 1.60.
Copolymer (2) of meq/g was obtained. On the other hand, both of the above monomers were subjected to solution polymerization using azobisisobutyronitrile as a catalyst and trichlorotrifluoroethane as a solvent to obtain a copolymer (2) having an ion exchange capacity of 0.70 meq/g. Next, 80 parts by weight of copolymer (1) and 2 parts of copolymer (2)
0 parts by weight were blended using a roll and further heated at 230°C.
It was press-molded to form a film with a thickness of 100μ.

After hydrolyzing the film in caustic soda,
It was treated at 0°C for 16 hours and then dried at 70°C for 24 hours to obtain a membrane with an ion exchange capacity of 1.42 meq/g. Using this membrane, a mixed solution of water and isopropanol (impropanol/water = 82/18. weight ratio) was separated by barbage separation. Temperature 40℃, permeate side pressure 10'mH
The separation coefficient for isoprono(nol) of water obtained at
Met.

Example 2 Tetrafluoroethylene and 0F2=CFOOF20F (OFs )o (OF2
) 1oooCHs to obtain two types of copolymers with ion exchange capacities of 1.40 meq/g and 0.72 meq/g. 75 parts by weight of the former and 2 parts by weight of the latter
5 parts by weight were blended on a roll to give an ion exchange capacity of 1.
It was made into a blend of 23 meq/g. A film with a thickness of 100 μm was obtained from the blend by press molding.

After hydrolyzing the obtained film in caustic soda, the functional group was changed to 1000H type in hydrochloric acid, and the film was diluted with 9% in pure water.
It was treated at 0°C for 16 hours and dried at 70°C for 24 hours.

Using this membrane, a mixture of water and ethanol (ethanol/water = 94/6. weight ratio) was separated by barbage separation. The separation coefficient of the obtained water with respect to ethanol at 40°C e 10 ""Hg was 5.52, and the permeation amount was 732 g/-.hr.

Procedural amendment (letter) April 1980, Japan Patent Office Commissioner Haruki Shimada1, Indication of the case, Patent Application No. 190698, filed in 19822, Name of the invention, Method for separating liquid mixtures3, 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 liquid mixture containing at least an organic liquid as one of its constituent components is prepared by using a polymer III consisting of at least two or more types of fluorine-containing polymers having different ion exchange capacities having carboxylic acid type functional groups. A method for separating a liquid mixture, characterized by separating it by paperage.