DE2207003A1 - Process for the manufacture of lined heterogeneous ionic membranes - Google Patents

Description

Dr. F. Zumstein Sr. - Dr. E. Ae
Dr. R. Koviiirj- ^ ctr?.: - r>'-'. ~ iv _J. ^. Ü '' -

Dr. P. Lurr. ..V. ; J.-i.
'Patent attorneys
3 Mönchen 2, Bräuhauistraße 4 / Iil

SC 5860

RHONE-POULENC S.A. - Paris, France

Method of making ir. With an insert

provided heterogeneous ionic membranes

The present invention relates to a method for producing heterogeneous ion exchange membranes provided with an insert.

Heterogeneous membranes are membranes that consist of a Combination of at least one ion exchange polymer and at least one polymer that does not exchange ions exist, this latter polymer generally being called "matrix" or also "binder".

Membranes provided with an inlay are called membranes which have a reinforcing support called an "insert". The inlays generally consist of a fabric, a mesh or a non-woven material.

The heterogeneous ion exchange membrane membranes provided with an insert are in particular from French patents 1 122 044, 1 123 5S3, 1 279 797 and 1 584 187 and British patents 823 077 and 873 903 known.

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Several techniques for making such membranes are also known. One such (British patent specification 823 077) consists in joining an insert (or several inserts) to a non-lined ion exchange film (or several such films) by hot pressing. According to a preferred embodiment, a symmetrical "sandwich" membrane is produced by pressing a film between two inserts or an insert between two foils. In any case, with this method, in the course of the production of the membrane, one must handle an ion exchange film which is not provided with an inlay. Such films are somewhat fragile, especially when the content of ion exchange resin in the resin-binder mixture is increased. They can be treated fairly easily if their surface area does not exceed a few square decimeters. However, if rr.an wants to manufacture membranes on an industrial scale (several square meters or several tens of square meters) continuously or semi-continuously, cracks, tears or tearing of the non-lined ion exchange films occur during the course of their treatment. Even after pressing these cracks, fissures or Einreissstellen remain or provide at least germs f ^{i #} lr an auto-destruction is, which have a tendency to reduce the maximum useful life of the .Membranen.

Another technique for making lined heterogeneous ion exchange membranes is coating (British Patent specification 873 903), possibly with the following Press. However, this technique has several disadvantages:

a) If one wishes the solvent of the coating mixture at least partially loosens the insert in order to better adhere this insert to the matrix-ion exchange resin system ensure, a weakening of the insert then occurs due to its solution, which causes particular coating difficulties comes with it, especially when trying to work continuously.

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b) If it is desired that the solvent of the coating mixture the insert does not loosen in order to avoid the disadvantages described above, then one is in the choice of the materials, which form this deposit, limited, which eliminates the usual and marketable deposits, such as fabrics vinyl chloride polymer.

c) It is difficult to get a regular coating surface to obtain in deposits with large meshes, their use in particular due to the small increase in the electrical Resistance that they bring with them is desirable. An irregular coating surface affects itself afterwards Pressing either through insufficient tightness of the equipment in which these membranes are used, or in a degradation the mechanical properties and / or the aging resistance of the membranes.

Finally, in French patent specification 1 279 797, for the production of membranes provided with an insert, apply the calendering, molding, sintering and casting techniques. The disadvantages of casting are those of coating. In addition, these various techniques do not make it possible to manufacture membranes on an industrial scale, whose inlay regularly is centered, causing irregularities in the mechanical or electrochemical properties.

There has now been a method of making liner heterogeneous ionic memoranda found that the disadvantages the previous method does not have and is particularly suitable for production on an industrial scale. This method is characterized in that the following operations are carried out in succession:

1) A solution or suspension of ion exchange resin is poured and binding agent on a continuous (i.e. free from holes) and flexible carrier film;

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2) the solvent is evaporated from the solution or suspension, resulting in a binary sandwich consisting of an ion exchange film on a flexible and continuous carrier film consists;

3) a ternary sandwich is made by inserting an insert and on either side of this two previously made binary sandwiches are united, the continuous and flexible ones Carrier foils are arranged outside;

4) the previously made ternary sandwich is pressed in the, Warmth;

5) one loosens the continuous and flexible carrier foils aD.

The method according to the invention is suitable for a large number of types of heterogeneous ion exchange membranes, but it is particularly advantageous for the production of membranes whose matrix consists of a vinyl chloride polymer. Under These vinyl chloride polymers can be linked to the homopolymer, the copolymers with vinyl esters of lower aliphatic acids (generally having 1 to 6 carbon atoms) and the copolymers with alkyl esters of unsaturated aliphatic acids, such as maleic acid and fumaric acid, in which the alkyl radicals generally have 3 to 10 carbon atoms, to name. The reduced specific viscosity of these vinyl chloride polymers (measured at 25 ° C in 0.5 pointer solution in cyclohexanone) is usually between 30 and 400 cnr / g, preferably between 50 and 150 cm / g.

If the matrix is a vinyl chloride polymer, the continuous and flexible carrier film used then preferably consists made of polyester and in particular of polyethylene glycol terephthalate. However, carrier films made of polyvinyl alcohol, Use polyamides, polyimides, and cellulose.

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The one used in the first stage of the process according to the invention Solution or suspension consists of:

a) an ion exchange resin

b) a binder

c) a solvent

d) optionally a plasticizer.

The type, the proportion and the dimensions of the ion exchangers Resin particles can in particular be those as described in French patents 1,056,884 and 1,556,896 and in US Pat DAS 1 042 541 and are preferably such as they are described in French patent 1,584,187.

The solvent is advantageously a solvent for the binder polymer. As a solvent that can be used, ir.an in particular acetone, acetophenone, cyclohexanone, butyrolactone, monochlorobenzene, methylene chloride, trichlorethylene, tetrachloroethane, Name epichlorohydrin, nitroenzene, pyridine and dimethylformamide.

The amount of solvent is such that the solution or suspension can flow as such at room temperature. Typically, one uses 40 to 80 wt -.% Solvent, based on the mixture.

The solvent can optionally be combined with a minor amount of a nonsolvent for the binder. Examples of nonsolvents in the case of vinyl chloride polymers can be methyl ethyl ketone, methyl isobutyl ketone, benzene, Name toluene, xylenes, cyclohexanol, aliphatic alcohols, chloroform, dioxane and ethyl acetate. These will be nonsolvents used in amounts such that the binder is still soluble in the solvent-nonsolvent mixture. The amount of nonsolvent is generally less than 40 wt .- ^ in the solvent-nonsolvent mixture.

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The solutions or suspensions used in the first stage of the process according to the invention can also contain a plasticizer or plasticizer, the type and proportion of which depends mainly on the binder used. If the binder is a vinyl chloride polymer, then as plasticizers that can be used are the alkyl, aryl or arylalkyl phthalates, phosphates and phosphonates, the esters derived from hydroxy acids and aliphatic diacids, the esters of polyols, the polymeric plasticizers, the hydrocarbons with high molecular weight and the derivatives of the aforementioned compounds which also contain amide, ketone or epoxy functions or chlorine atoms. These plasticizers are well-known products. They are usually present in proportions less than 20 wt -.%, Based on the binder, preferably below 5 wt -.%, Is used.

The evaporation of the solvent in the second stage of the process according to the invention takes place by guiding the continuous and flexible carrier film into an oven or via a heat source, for example a heating drum. The evaporation is usually continued until the content of the solvent content of the mixture resin-binder-solvent is less than 50% by weight , preferably less than 20% by weight.

If the binder is a vinyl chloride polymer and the continuous flexible sheet of polyethylene glycol terephthalate exists, one finds that the ion exchange film is attached to this continuous and flexible carrier film adheres, which ensures good cohesion of these two components and in particular prevent the cracks and tears of the ion exchange film.

As deposits that are used to make the ternary sandwiches in the the third stage of the process according to the invention can be used, in particular, the fabrics ÄSsxyinylchlorid, vinyl chloride vinylidene chloride copolymers, Polyethylene and polypropylene, the

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We call fabrics based on polyamide or polyester hair and fabrics based on glass fibers or metal thread.

The pressing, which is carried out in the fourth stage of the present process, takes place at a pressure between 5 and 110 bar, preferably between 15 and 70 bar, with the temperature between 50 and 200 ⁰ C, preferably between 80 and 15O ⁰ C, . In any case, this temperature is lower than the softening temperature or the melting temperature of the insert.

If the binder is a vinyl chloride polymer and the continuous and flexible carrier film consists of polyethylene glycol terephthalate, it is found after pressing that the Adhesion between this carrier film and the ion exchange film is extremely low, so that the dissolving that occurs in the fifth stage of the process according to the invention is carried out easily without detrimentally affecting the state of the Ion exchange film can be made.

The process according to the invention can be discontinuous or continuous or carried out semi-continuously.

It enables rr.it-lined ion exchange membranes with a well-centered insert and good electrical resistance to obtain.

In addition to the method described above, a variant of this method has also been found which enables membranes with improved To receive reinforcement, whereby this reinforcement comprises two deposits. This variant is the third Replace stage with the series of the following stages:

3.1. You combine two binary sandwiches, iniem they are arranged against one another, the carrier films being arranged on the outside;

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3.2. the arrangement produced according to 3.1 · is pressed in the heat;

3.3. the carrier films are detached from the, according to 3 »2 · produced pressed arrangement from;

3.4. a quinternary sandwich is made

here, the successive binary sandwich, one against the Resin-binder part of the binary sandwich arranged insert, the arrangement produced according to 3.3 · an insert and a having binary sandwich, the resin-binder part of which is arranged against the preceding insert (the carrier film is located outside).

In this variant of the method according to the invention, the fourth and fifth stages are retained as such, but they are applied to the quinternary sandwich described above and not to the ternary sandwich. The special conditions regarding pressing and heating and the types of deposits are in the main process according to the invention and its Comparable variant.

The following examples serve to further explain the Invention. The tests or measurements of the properties are carried out according to French patent specification 1,584,187.

example 1

A suspension of the following constituents is prepared by stirring from:

37 * 5 g of a mixture of cyclohexanone and methyl isobutyl ketone in proportions by weight of 70/30

15 * 9 ß anion exchange resin made from chloromethylated and aminated Styrene-divinylbenzene copolymer (ion exchange capacity: 1.5

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mval per gram of dry resin)

7 * 5 g vinyl chloride butylrr.aleat-copolymer in weight proportions of between 91 * 5 / 8.5 "reduced specific viscosity of the copolymer (measured at 25 ⁰ C in 0.5 ^ igerLösung in cyclohexanone) is 91 c.nr/e .

This brought to 30 ⁰ C suspension is poured in an amount of 10 kg / h in a continuous and flexible support backing of polyethylene glycol terephthalate with a width of 75 cm, wherein the support base is passed over a brought to 75 ° C heating drum. The duration of the evaporation of the solvent on this drum is 20 minutes.

The binary sandwich obtained is then cut into pieces 150 cm in length.

Two of these pieces are placed on an insert in such a way that the polyester carrier film is on the outside. The insert consists of a fabric made of polypropylene with 18 meshes per cm

and a weight of 28 g / m.

The ternary sandwich is pressed for > 0 minutes at 125 ^° C. under 25 bar.

An anion exchange membrane is obtained with the following properties:

Thickness when wet: 0.6 mm Substitution resistance: 12 \ j \ j cm

Permselectivity: 86 #

Burst pressure: 9 kg / cm
Example 2

The procedure is as in Example 1, but used as the ion exchange resin a cation exchange resin made from styrene divinyl

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benzene copolymer which has sulfonic acid groups and a Has ion exchange capacity of 3 * 5 meq / g dry resin. ,

The properties of the membrane obtained are as follows:

Thickness when wet: 0.4 mm Substitution resistance: 4 uu cm Permselectivity: 80 %

Example 3

The procedure is as in Example 2, but a cation exchange resin is used with an ion exchange capacity of 4 meq / g.

The properties of the membrane obtained are as follows:

Thickness when wet: 0.65 mm

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Substitution resistance: 6.5 uu cm Permselectivity: 84 %

Example 4

The procedure is as in Example 1, but an anion exchange resin is used with an ion exchange capacity of 2.2 meq / g.

Thickness when wet: 0.55 now resistance to substitution: 8 \ J ~ \ * cm Permselectivity: 80 %

Example 5

The procedure is as in Example 1, but modified as follows Way: The vinyl chloride-butyl maleate copolymer is reduced by a vinyl chloride homopolymer with a specific viscosity (measured as before) of 77 cmve replaced;

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the ternary sandwich is ^{pressed for 5 minutes at 135 °} C. under 60 bar.

The properties of the membrane obtained are as follows:

Thickness when wet: 0.52 mm Substitution resistance: 26 u \ / cm Permselectivity: 86 %

Example 6

A suspension is made by stirring the following ingredients from:

35 g of a mixture of cyclohexanone and methyl isobutyl ketone in proportions by weight from 70/30,

13 6 ion exchange resin used according to example 2,

7 g vinyl chloride-butyl maleate copolymer similar to that of Example 1 is comparable,

0.15 g octyl phthalate.

Subsequent work as in Example 1 is poured this suspension on a carrier film, produces a binary and then a ternary sandwich with an insert that consists of a Polyethylene glycol terephthalate fabric with a thickness of 0.17 mm and a weight of 28 g / m, which has 10 threads per cm.

After pressing as in Example 1, the continuous one can easily be removed and flexible carrier film. The properties of the obtained Membrane are the following:

Thickness when wet: 0.48 mm

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Substitution resistance: 4.7 \ S ~ \ j cm Permselectivity: 80 % Burst pressure: 4.5 bar

Example 7

The procedure is as in Example 6, but a polyethylene fabric with a thickness of 0.15 mm and a weight is used as the insert

weight of 82 g / m, which has 18 threads per cm.

The properties of the membrane obtained are as follows:

Thickness when wet: 0.5 ^ mm Substitution resistance: 7 \ f ~ \ j cm Permselectivity: 88 % Burst pressure: 17 bar

Example 8

The procedure is as in Example 6, but using a polyhexamethylene adipamide 0.14 mm thick and weighing as an insert of 95 g / m, which has 21 threads per cm.

The properties of the membrane obtained are as follows:

Thickness when wet: 0.5 mm Substitution resistance: 6.5 κ / \ ι ^ m Permselectivity: & 7 % Burst pressure: 11 bar

Example 9

The procedure is as in Example 2, except that the vinyl chloride butyl naleate copolymer is used by a vinyl chloride-vinyl acetate-malein-S'iure-conolymorcs in proportions by weight of 85 / 14.5 / 0.5 with a reduced specific viscosity of 52 cm / ^ replaced.

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The properties of the membrane obtained are as follows:

Thickness when wet: 0.45 mm Substitution resistance: 3 * 5 JV cm Permselectivity: 72> £

Example 10

The procedure is as in Example 2, but using a polyvinyl chloride fabric with a thickness of 0.19 mm and a

2 2

Weight of 30 g / rn, which has 35 meshes per cm, is used.

The properties of the membrane obtained are as follows:

Thickness in the wet state: 0.65 ram Substitution resistance: 4 u u cm Permselectivity: 71 % Burst pressure: 2 bar

Example 11

The procedure is as in Example 2, but a fabric made of Viriylchlorid-vinylidene chloride copolymer is used as an insert Thickness of 0.64 mm and a weight of 200 g / m, which has 6 threads per cm.

The properties of the membrane obtained are as follows:

Thickness When wet: 0.8 mm Substitution resistance: 6.8 \ j \ j cm Permselectivity: 75 % Burst pressure: 10 bar

Bo3 game 12

The procedure is as in Example 1, but used as an insert

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a fabric made of horsehair-like threads made of polyethylene glycol terephthalate with a thickness of 0.16 mm and a weight of 33 g / m, which has 22 threads per cm.

The properties of the membrane obtained are as follows:

Thickness when wet: 0.45 mm Substitution resistance: 11 \ J ^ \ j cm '' Permselectivity: 77 %
Burst pressure: 6 bar

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Claims (4)

22Q7QQ3 - 15 - Patent claims 1) j A process for preparing provided with insert heterogeneous Ionenaustauscnmemoranen, characterized in that one carries out the following operations in succession: 1.1. a solution or suspension of ion exchange resin is poured and binding agent on a continuous (i.e. free from holes) and flexible support base, 1.2. the solvent is evaporated from the solution or suspension and a binary sandwich, des from an ion exchange film and a continuous one and flexible carrier film, 1.3 nr.an makes a ternary sandwich, incier. man one insert and two binary sandwiches produced as above are combined on both sides, the continuous and flexible foils are arranged on the outside, 1.4. the ternary sandwich prepared as above is subjected to hot pressing and 1.5 · n: an loosens the continuous and flexible carrier foils away. 2) Method according to claim 1, characterized in that the binder is a vinyl chloride polymer and the continuous and a flexible carrier film made of polyester is used. 3) Method of making heterogeneous ion exchange membranes with double insert, characterized in that the following operations are carried out in sequence: 2Ü9636 / U824 3.1. a solution or suspension of ion exchange resin and binder is poured onto a continuous and flexible carrier film, 3.2. the solvent is evaporated from the solution or suspension and thus a binary sandwich is obtained, which consists of an ion exchange film on a continuous and flexible carrier film, 3.3. one combines two binary sandwiches in which one arranges them opposite one another, with the carrier films arranged on the outside, 3.4 · «one subjects the arrangement according to 3» 3 » a pressing in the warmth, 3.5. the carrier films are detached from the J> A. produced pressed arrangement, 3.6. one makes a quinternary sandwich, which successively a binary sandwich, one against the resin-binder part of the binary sandwich arranged insert, which according to 3 x 5. manufactured pressed Arrangement, an insert and a binary sandwich, the resin-binder part of which is against the previous one Insert is arranged, has, 3.7. the quinternary sandwich previously prepared is subjected to hot pressing and 3.8. the continuous and flexible carrier films are removed. 4. Ion exchange membranes produced by one of the methods according to one of claims 1 to 3 209836/0824