Method of new fluorinated polymers production

The invention relates to a solution or dispersion of a perfluorinated polymer. The solutions or dispersions according to the invention find particular application in the manufacture of ion exchange membranes.

Films or sheets of fluorinated polymers which are capable of ion exchange are widely used in industry, particularly as ion exchange membranes in chlor-alkali cells. Such membranes are made of fluorinated polymers having ion exchange active groups attached to pendant groups on the polymer chain.

These polymers are usually thermoplastic and can be melted into films or sheets, using a mechanical extruder. However, such a device operates in a temperature region close to the melting point of the polymer crystals, which is generally close to the decomposition temperature of some polymers. Therefore, decomposition can become a problem when some polymers are processed by conventional techniques into films. Similarly, these technologies make it difficult to process these polymers into films thinner than about 10 µm. In addition, it is difficult to produce films of uniform thickness · It would therefore be highly desirable to be able to produce films having a uniform thickness ·

Processing of Membrane Structures and Reinforcing Structures into Multilayer Structures It has been the subject of several patents and patent applications including U.S. Pat. No. 3,925,135,

However, these methods use complicated procedures and equipment, including such devices as vacuum manifolds, cylinder and release means.

The prior art processes for the production of perfluorinated polymer films are limited by the solubility of these polymers and the temperature dependence of the viscosity and shear rate relationship of these polymers. In order to overcome these properties of perfluorinated polymers based on carboxylic acid esters, the swelling of these polymers has been tested using various types of bottons and lowering the process temperatures of these polymers to a practical range by extraction. Extraction Methods These are described, for example, in U.S. Patent No. 4,366,501. The low-molecular-weight oligomers are removed from the carboxylic acid ester-based polymers. The polymer fluff * is extracted in a Soxhlet apparatus at atmospheric pressure for 24 hours (see Examples 1 and 3 of U.S. Pat.

36О 60l). It has been found that by such treatment certain fluorinated copolymers based on carboxylic acid esters achieve higher processability, and moreover such copolymers more effectively serve in the chlor-alkali cell when they are in hydrolyzed form. Such extractions modify molded articles from the polymer, for example, by forming a polymeric lubricant. As shown in Example 3 of US Patent No. 4,366,501.

In addition, such extraceses allow lower processing temperatures of the carboxylic acid ester polymer after isolation. The term isolation means separation from the polymerization latex by conventional surfactant-inactivating methods such as freeze-thawing, heating, shear stress, salting-out and pH adjustment.

British Patent No. 1,286,859 discloses that highly polar organic solvents dissolve a small amount of a fluorinated vinyl ether-totrafluorothylene copolymer in thermoplastic form. The term thermoplastic form means that the polymer is in a form that can be molded or processed above a transition temperature (such as a glass transition temperature or melting point) without altering the chemical structure or composition of the polymer. Patent Description There is use of solvents including butanol, ethanol, N, X-diraethvlacatamine and N, N-dimethylaniline.

A similar approach was used to swell membranes in ionic form. Ionic membrane forms are membranes that have been converted from thermoplastic form (-SO ^ F or -COOCH ^) to ionic forms (-SO ^ M or -COOM, where M stands for Η *, K *, Na⁺, NH4⁺ or Other metal ion).

High polar solvents or other mixtures have been used for substantially perfluorinated polymers and less polar solvents for fluorinated polymers containing hydrocarbon components such as co-monomers, thermonomers or thickeners.

CS 269 980 B2

However, each of these previously known methods of swelling, dispersion or extraction of polymers has certain drawbacks known to those skilled in the art. Polar solvents have the ability to absorb water or are reactive with functional groups during subsequent processing operations to provide poor coatings, films and the like. High boiling solvents are difficult to remove and often have toxic properties or are flammable. Functional forms (ionic films) of polymers can react with solvents (see Analytical Chem., 1982, vol. 54, pp. 1639-1641).

More polar solvents, such as methanol, butanol esters, and ketones, as disclosed in U.S. Pat. 1,286,859 and Chem, Abstr. 79 О6856, have a high vapor pressure under ambient conditions, which is suitable for solvent removal but tend to absorb water. Their water content is undesirable because it can cause problems in the production of continuous coatings and films of hydrophobic polymers. In addition, polar solvents often leave residues that are incompatible with polymers, and also often leave residues that may react during subsequent chemical or thermal operations if they are not subsequently removed.

In another variation, within the prior art, high molecular weight solvents are used in the production of fluorinated polymer films which are produced by halogenated vinyl ether monomers (British Patent No. 2,066,824).

The swelling of functional (ionic) forms of fluorinated polymers by polar or hydrophilic means has already been known. In addition, the solvent solubility parameters were compared to the swelling effect of the 1200 equivalent Nafion ion exchange membrane (available from EI DuPont Company) of Yeo at Brookhaven Laboratory (see Polymer, 1980, vol. 21, p. 432).

Swelling was found to be proportional to two different Solubility Parameter Intervals and a calculation was developed to optimize the solvent mixture ratios. The ionic forms of the functional fluorinated polymers can be processed in such a way, but the subsequent physical forming or processing of the polymers to conventional configurations by hot-processing is limited when the polymers are in functional forms. In addition, the temperature range of thermoplastic treatment of nonionic forms of polymers is also limited by the stability of functional group bonds.

Other solvation methods used temperatures close to the melting points of the crystalline phase of the polymers to be solvated. This requires either a high boiling point of the solvent or a high pressure vessel to keep the system in a solid-liquid state (see Annalsioal Chem., Vol. pp. 1639-1641 (1982)].

Burell notes that the theory of Baglay / J. Paint Těch., Vol. 41, p. 495 (1969)] predicts that the non-crystalline polymer will dissolve in a solvent of similar solubility parameters without chemical similarity, association or any intermolecular strength. However, it does not mention the solubility of polymers exhibiting crystallinity.

SUMMARY OF THE INVENTION The present invention provides a perfluorinated polymer solution or dispersion comprising a perfluorinated polymer comprising units derived from the first monomer of Formula I

CF₂ - czz '(i) wherein and Z * are substituents independently selected from the group consisting of hydrogen, chloro, fluoro and trifluoromethyl; and

Units derived from the second monomer of both patterns II

Y- (CF₂) and - (CFR_F) b- (CFR_F»)_O-O- / CF (CF₂X) -CF₂-O/_n-CF = CF₂ (II)

CS 269 98О B2 where

Y o

with the condition that the sum

X is a substituent selected from the group consisting of -SO_OZ, q L 2 is a cyano group, a group of the formula -COZ and a group of the formula c (R 2)^J_F) (r _F) O, where Z is an iodine, bromine, fluorine, fluorine atom, a group of formula OR nobo a group of formula NRjR₂, R represents a branched or straight C 1 -C 10 alkyl group or an aryl group,

Я? and R f are independently selected from perfluoroalkyl groups and from 1 to 10 carbon atoms, and R 6 is selected from the group consisting of:₂ are independently selected from the group consisting of hydrogen, branched or straight-chained groups, means means alkyl groups having 1 to 10 carbon atoms and aryl groups;

R_F and R_F'

O ii

O ia + b + o number number up to or 1, »is not equal to 0, means a atom of halogen, bromine or fluorine or its direction, if n is greater than 1, represents a number of 0 to 6 and are independently selected from the group consisting of fluorine, chlorine, C 1 -C 10 perfluoroalkyl, dissolved or dispersed in a solvent; or>

carbon atoms and a fluorofluoroalkyl dispersion medium of the formula

IV

XCF₂ - CYZX * (IV) who

X

X *

Y and Z include fluoro, chloro, including chloro, bromo and bromo;

Iodine means an atom selected from the group consisting of independently selected from the group consisting of hydrogen, fluorine, chlorine, bromine, iodine and R R wherein r 'is selected from perfluoroalkyl at a dissolved or dispersed concentration ranging from 0.1 to 50 % iodine, from the group consisting of porfluoroalkyl groups and chlorine groups having from 1 to 6 carbon atoms, of the dispersed perfluorinated polymer in a solution by weight, or

In the above formulas, X and X * are preferably chlorine. Y is particularly preferred when Y is -SO₂F or -COOCHy O or 1, R f and R 6 are fluorine atoms, X is chlorine or fluorine atom and a + b + o is 2 or 3 · or bromo, n is the sum of t

In addition to the monomer units of the formulas I and II, the perfluorinated polymer may also contain monomer units of the formula III (III) ^Y'^(CF2⁾and'^{(€ Fn}f) b '^(CFR'F⁾O⁰^{ZrCF (CF}2^X'⁾^CF2^_^ n '^{CF = CF}2

<td>where Y * a 'ab *</td><td>represents a fluorine, chlorine or bromine atom, independently from 0 to 3,</td>

<td>C</td><td>means 0 or 1,</td>

<td>3 condition, • n</td><td>that * the sum of a * + b '+ o * is not 0, meaning 0 to 6,</td>

<td>R_F and R_F*</td><td>They are independently selected from the group consisting of bromine, chlorine, fluorine, perfluoroalkyl of 1 to 10 carbon atoms and chloroperfluoroalkyl of 1 to 10 carbon atoms, and</td>

<td>X '</td><td>means a fluorine, chlorine or bromine atom or a mixture thereof when n 'is greater than 1</td>

CS 269 980 B2

The solvent or dispersing medium has a boiling point β preferably in the range from 30 to 110 ° C and its solubility parameter preferably lies in the range from 7.1 to 7.5 hildebrands.

A particularly preferred solvent and / or dispersing medium is 1,2-dibromotetrafluoroethane (known as Freon 11¼V 2)

BrCFg - CF₂Br and 1,2, 2-triohortrifluoroethane (known as Freon 113) cif₂ - cci₂F.

Of these two solvents and / or dispersing media, 1,2-dibromotetrafluoroethane having a boiling point of about 47.3 ° C, a density of about 2.156 g / onr and a solubility parameter of about 7.2 hildebrands is most preferred.

The term dispersion, as used herein, means a composition comprising a dispersing medium and a perfluorinated polymer as hereinbefore defined comprising sites convertible into ion exchange groups, wherein a portion of the polymer Jo is dissolved in the dispersion medium and a portion dispersed.

The invention can also be used to produce ion exchange resins, films and articles for use in olefins, films, and fluids and liquids.

Preferred for use in the present invention are the nonionic forms of perfluorinated polymers described in U.S. Pat. Nos. 3,282,875, 3,909,378, h 025,405, 4,065,366, 4,116,888, 4,112,336.

126 588, 4,151,052, 4,176,215, 4,178,218, 4,192,725, 4,219,635, 4,221,227, 4,251,333, h 270,996, 4,329,435, 4,330,654, 4,347,137, 4,347,211 , 4,340,680, 4,357,218, 4,358,412,

5458,545, h hv? Nos. 969, 4,462,877, 4,470,889 and 4,478,695 and European Patent 6. 0 027 009.

Such polymers typically have an equivalent weight in the range of 500 to 2000.

Ionox group -convenson It is well known in the art and is based on the interaction with an alkali metal solution.

Accordingly, it has been found that certain perhalogenated solvents and / or noble dispersing models have a surprising effect on the dissolution and / or dispersion of the polymers as defined above, especially when these polymers are in finely divided state.

It is important that the solvent and / or dispersing medium have a boiling point of from 30 to 110 ° C. The ease of removal of the solvent and / or dispersing medium and the degree of its removal are important in the production of various films, coatings and the like. media. Therefore, an acceptable boiling point at atmospheric pressure allows easy handling at ambient temperature, while still retaining effective removability of solvent and / or dispersing medium by atmospheric drying or gentle heating.

Further, it is important that the solvent and / or dispersing medium have a density of 1.55 to 2.97 g / m 2. The polymers of the invention have a density of the order of from 1.55 to 2.2 g / m 2, in particular from 1.6 to 2.2 g / m 2. The swelling, dissolution and dispersion of small particles of this polymer in the solvent and / or dispersion media of the present invention thus aid in the suspending effect which occurs due to the similarity of densities.

Monomer vzoroe

FSO₂CF₂CF₂OCF = CF₂ it has a density of about 1.65 g / m 2 and polytetrafluorothylene has a density of about 2.2 g / m 2. Thus, the copolymer of this monomer with totrafluorothylone would have a density between the two values.

CS 269 98B B2

According to the prior art, the density was not monitored, and therefore no attempts were made to adjust it. According to the state of the art, the interest has focused on the formation of solutions and there is no separation of solutions.

The solubility parameters are related to the cohesion energy density of the compounds. The calculation of solubility parameters is described in US patent δ. 4,348 ЗЮ ·

Importantly, the detergent and / or dispersing medium had a solubility parameter ranging from 7.1 to 8.2 g hildebrands. Similarity of cohesive energy densities between solvent and polymer determines the likelihood of dissolution and swelling of the polymer into solvent and / nobo dispersion model ·

It is preferred that the solvent and / or dispersing medium have a vapor pressure of up to about 100 kPa over a speoified temperature range in which the solvent and / or dispersant is removed. The solvent and / or dispersing medium should be easily removed without the need to use higher temperatures or reduced pressures, including prolonged heating, as would be necessary in cases similar to U.S. Patent No. 3,692,569 or British Patent No. 2,066 824, where it was necessary to use low pressures (395 Pa) as well as "non-solvents" to compensate for the high boiling points and low vapor pressure of complex solvents.

As mentioned above, a particularly preferred solvent and / or dispersing medium is 1,2-dibromotetrafluoroethane and 1,2,2-triohortrifluoroethane. Of these two substances, 1,2-dibromotetrafluoroethane, which has a boiling point of about 47.3 ° C, a density of

1) 156 g / onr and a solubility parameter of about 7.2 hildebrands ·

1,2-Dibromotetrafluoroethane works particularly well · Although not directly polar, it is highly polarizable · Because when 1,2-dibromotetrafluoroethane is assimilated to a polar molecule, its electron density shifts and causes the compound to flex like a polar molecule. when 1,2-dibromotetrafluoroethane is in contact with a non-polar molecule, is treated as a non-polar solvent · 1,2-dibromotetrafluoroethane therefore tends to dissolve both the non-polar main chain of polytetrafluoroethylene and such pendant polar groups contain ion exchange groups · The 1,2-dibromotetrafluoroethane solubility parameter is calculated to range from 7&gt; 13 to 7&gt; 28 hildeb ·

It is surprising that a commercially available compound such as 1,2-dibromotetrafluoroethane acts as a solvent and / or dispersion medium for the fluorinated polymers described above. Still more surprisingly, 1,2-dibromotetrafluoroethane accidentally has such a boiling point, density and solubility parameter. that they are particularly suitable for use as a solvent and / or dispersing medium according to the invention;

In practicing the present invention, the polymer may be in any physical form. Preferably, however, it is in the form of fine particles to facilitate dissolution of these particles in a solvent and / or dispersion medium. Preferably, the particle size of the polymers is from 0.01 to 84 µm. More preferably, the particle size is less than 250 µm.

In order to dissolve or disperse the polymer particles in the solvent and / or dispersing medium, they are contacted with the selected solvent and / or dispersing medium and mixed thoroughly. The polymer and solvent and / or dispersing medium may be mixed in any manner, such as by shaking, agitating, grinding or mixing by ultrasound. The list of possibilities is not limited by the examples given. For optimal dissolution, perfect contact of the brain with the polymorph and solvent and / or dispersion medium is required.

The polymers of this invention dissolve in a solvent and / or dispersion medium to a concentration of up to 0.5% by weight of the polymer based on the solvent and / or dispersing medium. At concentrations below 0.1% by weight, insufficient amounts of polymers are dissolved to allow the solution to be used as a coating composition for the coating of nobody films, with a reasonable number of repetitive deposition operations. Typically, about 0.5% by weight of the polymer is dissolved. Higher concentrations of polymers in the solutions can be obtained by evaporating the solvent from the solutions produced, up to the solubility limits of the polymers.

O

CS 2 9 980 B2

The polymers of the present invention may also dissolve and / or disperse in a solvent and / or dispersing medium at a concentration of from 0 to 0._F1 % to about 50% by weight of the polymer, relative to the solvent and / or dispersing medium. At concentrations above about 50% by weight, an amount of polymer is present as a separate phase such that acceptable coherent films and uniform structure-free films without agglomerates, and the like can no longer be formed.

Preferably, the polymer concentrate in the dispersion medium is from 1 to 20% by weight. The most preferred conjugates of the polymer in the dispersion medium are from 5 to 15% by weight.

The dissolution or dispersion of the polymer in the solvent and / or dispersing medium can be carried out at room temperature. In general, optimum dissolution is achieved at temperatures of from 10 to 50 ° C. However, at temperatures above 50 ° C, the dissolution of the polymer in the preferred solvents must be carried out at elevated pressure or the solvents condensed. Conversely, at temperatures below 10 ° C, a significant proportion of the polymers of this invention are below the glass transition temperature. creates solutions under appropriate mixing, mixing or grinding conditions ·

The dissolution or dispersion of the polymers of the present invention in the solvent and / or noble dispersion medium is best accomplished at atmospheric pressure. Obeone can effectively achieve a dissolution at a pressure of 100 kPa to 2 MPa or higher. Working at pressures below 100 kPA does not provide any advantages in dissolving the polymers, since it prevents the solvent from penetrating into the polymers and thus prevents the formation of solutions.

On the other hand, pressures above 100 kPa help to dissolve and disperse the polymers very little in comparison to the difficulty and complexity of the pperaoe.

The solutions or dispersions produced according to the invention can be fixed to other polymorphic films or substrates by sintering or pressing the polymer deposited from the solution or dispersion onto the substrate.

For fixing a polymer from a solution or dispersion of the invention to a substrate, the following methods are suitable: Dipping the substrate in solution or dispersion, then air drying and sintering at the desired temperature with sufficient number of repetitions to achieve the desired thickness. Solution spraying is preferably used to cover large nobo irregular shapes. Pouring a solution or dispersion onto a substrate is sometimes used. Painting the solution or dispersion with a brush or roller is also successfully used. In addition, the coating can be easily carried out by the application of knives or skates. Usually, coatings or films achieve the desired thickness by repeated drying and sintering.

The type of substrate to which the solution or dispersion of the present invention may be applied may include such materials as glass, polytetrafluoroethylene strips or sheets, electrodes in the form of a scrim, mesh, made, for example, of carbon, polytetrafluoroethylene or metal fibers, sheets or other polymeric films or articles.

The substrate to which the solution or suspension is to be applied is cleaned or treated in such a way as to ensure uniform contact with the solution or dispersion. It can be cleaned by washing with a degreaser or solvent and then dried. Metals should normally be acid etched and then optionally washed with solvent to promote adhesion. · If the metal is new, it is sufficient to degrease it.

After cleaning, the substrates may be pretreated by heating or vacuum drying before contacting the solution or dispersion during coating. Preferably, temperatures and pressures in this range of about 2.7 kPa at about 110 ° C are used. It is satisfactory in all cases, but moderate heating to about 50 ° C at atmospheric pressure is usually sufficient.

CS 269 980 B2

After preparation, the substrates are coated with a solution or dispersion by any one of several application methods, such as dipping, spraying, brushing or casting *, which is not limited thereafter. The solution or dispersion can be applied in a single stage or several steps depending on the polymer concentration in solution and the desired coating or film thickness.

After application of the solution or dispersion, the solvent and / or the dispersing medium is removed by any method * including but not limited to evaporation and extraction * but not limited to * extracoustically using one of the means * which selectively dissolves the solvent and / or dispersing medium or * but which dissolves the polymer and does not mix with it

The solvent and / or dispersion medium is removed until a uniform deposition of polymer is obtained and a continuous film is formed.

Removal of the solvent and / or dispersion medium is generally carried out by maintaining the coated substrate at a temperature in the range of from 10 to 110 ° C, preferably at a temperature in the range of from 20 to 110 ° C. or dispersing medium ·

The heating temperature is usually in the range of 20 to $ 0 ° C for 1 * 2-dibromotetrafluoroethane ·

The pressures used to remove the solvent and / or dispersing medium from the coated substrate may range from 2 to 7 kPa to 100 kPa depending on the nature of the solvent and / or dispersing medium * although for 1 * 2-dibromotetrafluoroethane, common pressures are 40 to 100 kPa. .

The coating or film formation may be performed as part of the polymer deposition and solvent removal and / or dispersion medium removal process or as a separate step by * adjusting thermal and pressure conditions * under which the polymer separates from the solvent and / or dispersion medium. and / or the dispersions are applied in several successive stages * a continuous film or a crater-free coating * can be formed without any subsequent heating above room temperature only by: controls evaporation rate · This can be achieved by vapor-liquid equilibrium * in the vessel or adjacent space · Therefore, the solvent removal and / or dispersion medium removal stage may consist solely of a drying stage or a controlled coating or film forming process · If the solvent and / or dispersion medium removes by flash evaporation * film does not form without a separate degree of heating ·

Thereafter, the solvent and / or dispersion medium is removed * preferably, in a separate stage, the remaining polymer is contacted with a heat source at 20 to 380 ° C for 10 seconds to 120 minutes * depending on the thermoplastic properties of the polymers. which have a melt viscosity of the order of 5, 1 (/¹ Pa, s at a temperature of about 300 ° C and a shear rate of 1 в¹ (as measured by a conventional capillary rheometer) would require longer times and higher temperatures within the halo group stability interval. · Polymers with viscosities of the order of 0 * 1 Pa, and would require no further processing at room temperature. .

The most preferred conditions for this treatment * for the most preferred polymers used according to the invention * are at a temperature of 270 to 350 ° C and a time of 0 * 2 to 45 minutes. Such polymers form continuous films under the conditions described above.

Films of different oh thicknesses can be easily produced using the methods and apparatus described above. When in ionic form, such films are suitable as membranes for use in electro-electro-softening, these films are particularly suitable for the electrolysis of brine solutions, i.e. sodium chloride solution. * which produces gaseous chlorine and sodium hydroxide solutions. The obtained motrates have surprisingly good current properties when used in chloroalkali metal salts.

CS 299980 B2

Example 1

The polymer solution is prepared from monomers of formulas I, II and III

<img file="CS269980B2_D0001.tif" />

CF - O - cf₂ - cf₂ - cf₂ - Cl (I)

<img file="CS269980B2_D0002.tif" />

CF

CF-O-CFg-CFj

CO - O

<img file="CS269980B2_D0003.tif" />

(II)

Hoztolc torpolymoru eo prepared by poatupomi

7.0 g of the monomer of formula I and monomer of the formula II are added to 400 ml of oxygen-free water containing 3 g ^TO2^WITH2 ° 8 1.5 g of Na 2 HPO 4 and 3.5 in C 4 F 4 COgK at a positive pressure of the monomer of formula III in a glass-lined I / L reactor at a temperature of 25 ° C and a positive pressure of 482 kPa The mixture is ventilated and acidified with 50 ml of concentrated hydrochloric acid to obtain latex coagulation. The polymer is washed extensively to remove residual salt, soap and monomers. A portion of the terpolymer is dissolved in 150 ml of BrCF? CF? Br by stirring 20 g of terpolymar in this solvent at a roflex temperature of 47.3 ° C for 2 hours Thus, at least a portion of the polymer is dissolved in the solvent. The solution is analyzed by evaporating a portion of it and determining the weight of polymer remaining in the vessel. The solution was found to contain 0.3% by weight of polymer. 50 ml of this solution is poured into a petri dish and the solvent does not evaporate. A continuous polymer film is obtained at the bottom of the dish. This film is hydrolyzed with a solution of potassium hydroxide in methanol at a concentration of 15% by weight for 1 hour at 5 ° C. The polymer thickness is determined to be 50.8%.

<img file="CS269980B2_D0004.tif" />

Example 2

A copolymer is prepared from the compounds of formulas CF ^ = CF a and CF ^ with CFOCF ^ CF CFSOgF having an equivalent weight of 1144. The preparation of the copolymer is as follows:

784 g of a compound of formula CF CF with CFOCF ^ CF ^SO ^F is added to 4700 g of deoxygenated water containing 25 g of NH ^C ^F F, 18.9 SΝβ, ΗΡΟΗΡΟ. 7H₂0. 15.6 g of NaHgPO4. H₂0 and 4 g (NH4S2O2) at a pressure of tetrafluoroethylene of 1 722 kPa at 60 DEG C. for 58 minutes. The reactor is ventilated under vacuum and heat to remove any remaining monomers. The reactor contents are frozen, thawed and washed thoroughly. to remove residual salts and soap · After drying under reduced pressure, a dispersion is prepared that 56 g of the polymer prepared as described above and 168 g of 1,2-dibromotetrafluoroethane are introduced into a Morton Jar Milí porcelain ball mill with a speed of 290 min.¹The mixture is mixed in a ball mill over noo at ambient temperature at atmospheric pressure.

300 g of 1,2-dibromotetrafluoroethane are added to the resulting soft paste and the mill is rotated for an additional 3 hours. The resulting dispersion contains 12.5% ​​by weight of polymer. The mixture is coated with an aluminum foil with a thick film.<img file="CS269980B2_D0005.tif" />by soaking in dispersion ·

The coated aluminum foil is allowed to bend in air again. At room temperature, the dispersion medium evaporates from the dispersion.

The coated aluminum foil is then heated to 300 ° C in a muffle furnace for 1 minute to achieve sintering of the polymer to form a more uniform film.

The resulting film was found to be continuous and has a thickness of 12.7 µm.

The soaking and heating process is repeated five times until a polymer film of 63.5 Λ * π&gt; · is applied.

Two pieces of aluminum foil that have been coated as described above are pressed together with the coated side to the coated side at a pressure of 5&gt; 512 MPa at 313 ° C for 4 minutes · The resulting aluminum foil film on both sides is hydrolyzed for 16 hours

<img file="CS269980B2_D0006.tif" />

CS 269 980 B2 in 25% by weight aqueous sodium hydroxide solution at 90 ° C · This process dissolves the aluminum foil and leaves only a two-layer Г11вц which is tested in a chlorine-alkaline membrane cell · The salt is operated at 89 ° C and current density 0.31 A / cm²based on the electrode surface area with a 3 mm gap between the anode and the cathode. A cathode having an electrocatalyst on its surface is used. The cell voltage is 3.11 V at about 12.9% by weight. · Caustic efficacy based on sodium hydroxide Jo 92.2 The caustic produced in the cathode compartment contains 1030 ppm of sodium hydroxide according to the analysis.

Example 3

A polymer was prepared from compounds of the formulas CF 2 = CF₂ and CF ^ CFOCF ^ CF ^ CO ^ CH ^, which has an equivalent weight of 874 · The procedure is as follows:

g of a compound of the formula CF 3 CF 3 CF 3 CF 3 O 2 O 3 CH 3 is added to a glass reactor to 300 g of deoxygenated water containing 3.0 g NH 4 O 4 CC 4 F 3, 1.5 g Na 2 HPO 4 · 7H₂0.1 g of NaH₂P0 ^. H ^O and 0.20 g (ΝΗΝΗ^^ za) at a pressure of tetrafluoroethylene of 1722 kPa and at 50 ° C for 180 minutes · The reactor is vented and the contents of the reactor are acidified with 6N hydrochloric acid to coagulate the polymer · The coagulated substance is filtered off g of polymer is milled and blended over noo with 315 g of 1,2-dibromotetrafluoroethane in a laboratory porcelain ball mill as described in Example 1;

According to the analysis, the dispersion medium contains 10% solids by weight · Dispersion is used to coat aluminum foil with a thickness of 38 µm by dipping · The coated foil is allowed to bend again to air and the coating is sintered at 250 ° C for 1 minute in muffle peoi, which is described in Example 1 ·

This coating process is repeated until a series of coated films having different coating thicknesses are produced. From 2 to 5 coatings, various films having a sintered coating thickness of 17.8 to 48.6 µm are obtained.

The coated films are then molded onto 850.6 equivalent fluorosulfonyl copolymer films having a thickness of 101.6 µm. A 850 equivalent polymer is prepared as the fluorosulfonyl copolymer in the foregoing example, except that a pressure of 1323 kPa and 88 times are used. minutes · Dry polymer is extruded at a temperature of 260 to 288 ° C using a Haake Rheomiex 254 ventilated screw extruder,

1.9 om 9 ratio to length 25: 1, and stainless steel ooeli 316, with a 15.24 µm hub · A 508 µm hubioid film is extruded and elongated with a thickness of 101 to 127 µm, which is sharply cooled on an unheated roll ooeli 316 stainless steel film samples are degreased with acetone and air dried. The coated side of the film is placed towards the extruded film and the assembly is placed between two sheets of polytetrafluoroethylene coated glass fabric. The whole set is then pressed at 250 ° C in a hydraulic heated press using a force of about 200 kN for 5 minutes ·

The laminates are hydrolyzed in an aqueous solution of sodium hydroxide at a concentration of 25% by weight at 90 ° C for 16 hours. This process dissolves the aluminum foil on all laminates. 56 om² and contains titanium anode compartment and pexiscus cathode compartment · Anode Is a ruthenium plated oxide coated electrode · The cathode has an electrocatalyst surface · During operation, a direct current of current density relative to the electrode surface of 0.3 A is passed over the electrodes / cm, 20% NaCl solution is introduced into the anode compartment and water is added to the cathode compartment. The membrane is placed between the electrodes and screwed over the two halves of the cell, each containing a gas outlet and an overflow.

CS 269 980 B2 on these films Are summarized in the following © © I.

Table I

<td>sample no.</td><td> 1</td><td> 2</td>

<td>as many times as possible</td><td> 2</td><td> 5</td>

<td>coating thickness (µm)</td><td> 20</td><td> 46</td>

<td>film thickness (µm)</td><td> 5,1</td><td>10 * 2 to 15 * 2</td>

<td>current efficiency * based on</td><td></td><td></td>

<td>sodium hydroxide (¢)</td><td> 95,6</td><td> 96,7</td>

<td>voltage (v)</td><td> 3,22</td><td> 3,33</td>

<td>sodium hydroxide</td><td> 34,7</td><td> 35,4</td>

<td>consumption (kWh / 1000 kg NaOH)</td><td> 2256</td><td> .2307.</td>

<td>The current efficiency relative to sodium hydroxide is</td><td>sets to</td><td>based on the quantity ratio</td>

The amount of sodium hydroxide produced during the test period in moles is therefore divided by the time in seconds and multiplied by the current during the test period and the result is divided by 98 520 ooulombs per equivalent (Faraday charge). The resulting decimal fraction represents the proportion of electrons * that produce sodium hydroxide · This fraction times 100 gives the current efficiency relative to sodium hydroxide ·

The above data obtained after 13 days of operation does not change substantially after 90 days of operation.

Example 4

A copolymer is prepared from compounds of the formulas CF 9 CF 3 and CF 9 = CFOCF 9 CF 6 CO 2 * which has an equivalent weight of 755. which contains 3.0 g NH 4 O 4 CC 4 F 4, 1 * 5 g NagHPO 4. 7HgO, 1.0 g NaHgPO4. HgO and 0 * 10 g (NH4gSgOg) at a pressure of tetrafluoroethylene of 1619 kPa * at 50 ° C for 5 hours. The reactor is vented and acidified with 6N hydrochloric acid to achieve latex coagulation. The coagulated substance is filtered off and washed thoroughly to remove inorganic compounds and soap. The polymer is dried under reduced pressure at 85 ° C for 16 hours. .

g of the polymer thus prepared is comminuted in a 135 [deg.] C. laboratory dish

1,2-dibromotetrafluoroethane to form a viscous dispersion. The dispersion was used to coat an aluminum foil * having a thickness of 38 * 1 µm. The coated film is compressed in a heated hydraulic press at a pressure of 13,780 kPa and a temperature of 282 ° C for 4 minutes and 20 seconds between two glass-reinforced cover sheets of tetrafluoroethylene sheets.

The covering sheets are removed from the first polymeric film and the coated side of the folio is applied to the second film having a thickness of 127 µm of ion-exchange polymer.

To attach the first film to the second film, a pressing operation is repeated using a pressure of 4616 kPa. The resulting bilayer film was hydrolyzed in an aqueous solution of sodium hydroxide at a concentration of 25% by weight for 16 hours at 90 ° C. In this process, the aluminum foil is dissolved. The two-layer film is mounted in the test cell so that the polymer having an equivalent weight of 7-55 adheres to the cathode space.

The test alkali metal cell was maintained in service for 190 days under the conditions set forth in Example 2. The cell produces gaseous chlorine and sodium hydroxide by electrolysis of the sodium chloride contained in solanoe. Sodium hydroxide is obtained in the form of an aqueous solution having a concentration of 33% by weight at a current density based on sodium hydroxide of 95.6% and a voltage of 3 * 38V.

CS 269 98B B2

1

Example 5

According to the procedure described below, a copolymer is prepared from compounds of the CF patterns₂ = CF 4 and CF₂ = CFOCF ^ CFgCOgF with an equivalent weight of 116O · g of the compound of formula CF ^ and CFOCF ^ CFgSO4F is added to a glass reactor to 300 ml of deoxygenated water containing 3 g of NH4CO3Cf Ft, 1.5 g of Na2 HPO ^. 7H₂0.1 g of XaHgPO4 · H4O and 0.1 g (NH4)₂SgO at a pressure of 1688 kPa of tetrafluoroethylene at 60 ° C for 75 minutes · The reactor is ventilated hot and acidified to coagulate the latex · The coagulated polymer is washed repeatedly to remove inorganic compounds and soap · Polymer dried under reduced pressure at 110 ° C for 16 hours · g of the fluorosulfonyl copolymer is comminuted with 270 g of 1,2-dibromotetrafluoroethane in a laboratory three bowl until a viscous dispersion is produced ·

This dispersion is used to coat an aluminum foil having a thickness of 38.1 µm. The coating is not allowed to get airborne. The coated foil is placed on both sides with glass-reinforced polytetrafluoroethylene sheets and the resulting assembly is pressed in a heated press between two ooel plates with a shiny gloss. C and pressing time 4 min. 20 sec. After removing the cryo sheets, film 9 is obtained with a thin polymer film.

As a second copolymer, a copolymer of compounds of the formulas CF 4 = CF is prepared₂ and CFg = CFOCFgCF ^ SOgF with an equivalent weight of 974 * The polymer is prepared as follows:

784 g of a compound of formula CFg and CFOCFgCP ^ SO ^ F is added to 4 700 g of deoxygenated water containing 25 g of NH4CO4F ^, 18,9 β Na₂HPO4 · 7H₂0, 15.6 g ЙаН₂РОц · H₂0 and 4 g (NH4)₂WITH₂0g under tetrafluoroethylene overpressure of 1516 kPa at 60 ° C for 30 minutes · Reactor is vented under heat and reduced pressure to remove residual monomers · Reactor contents are frozen, not thawed and washed vigorously to remove residual salts and soap · Film dried under reduced pressure at 85 ° C for 16 hours ·

The second film is extruded on a commercially available Killion laboratory extruder with regular cylindrical body (Xaloy) and screw · screw is a standard type commonly used to extrude polyethylene * The blown film is produced using a 3.2 µm hubioe with a 608 µm slit, when heated to 288 ° C without using a smoothing ring · Extraction works at a temperature of 232 to 288 ° C at a speed of 20 to 40 min *¹· Draw-off mechanioké device - for film winding works with a speed of 30 to 60 om / min · Blown films are produced in various thicknesses according to need by changing the speed and degree of bag blowing ·

The extruded polymer film of 127 µm thickness from the fluorosulfone copolymer (84K3O23) is placed against the coated side of the film, compression is performed under the above conditions except · The two-layer film obtained is hydrolyzed in an aqueous solution of sodium hydroxide at a concentration of 25% by weight for 16 hours at 90 ° C. · The film is etched in this process. The resulting two-layer film is placed in a test cell. It is described in Example 3) so that the polymeric side 83PO19 is facing the cathode compartment. After two days, the following results are obtained: Cell voltage 3&gt; O2 V and current efficiency based on sodium hydroxide 9b 5 * b at konoentraoi sodium hydroxide 12.56 $ w / w, kononontraoe sodium chloride in sodium hydroxide 940 ppm, energy consumption 2211 kWh per 1000 kg sodium hydroxide ·

Nobo Dispersion Solutions of the Invention Can be used to treat (apretaoi) polytotrafluoroethylone fabrics

Polytetrafluoroethylene fabrics Woven products of polytetrafluoroethylene yarn or tows · Such products are available in many kinds from a variety of distributors, such as Stem and Stem Textiles, Incorporated, New York, New York, USA, under the designation T41-3O · This product has in the form of a leno-woven fabric with 45 x 21 paleo warp threads and having a thickness of 0,25 µm and having a mass per unit area of ​​147,5 g / m².

2

CS 299980 B2

Polytetrafluoroethylone fabrics are used for a variety of purposes, such as for the manufacture of filters, screens, reinforcements, sealants, insulation, linings, and gasketing elements.

These fabrics are also used as carriers for films of fluorinated polymeric ion exchangers. Such films are used as ion-exchange membranes in electrolytic cells.

Fabrics of fluorinated polymers are confined and exhibit little friction between the fibers. This causes these fabrics to deform under normal handling and to create holes in them without breaking the fibers.

Until now, attempts to coat polytetrafluoroethylene fabrics have been unsuccessful. The present invention provides a suitable method.

Polytetrafluoroethylene fabrics They are flattened before finishing. During handling, the fibers tend to slip, which makes it very difficult to handle them without changing the shape of the fabric. The solutions and / or dispersions according to the invention make it possible to finish polytetrafluoroethylene fabrics.

Polytetrafluorothylene fabrics Suitable for use herein The fabrics are commercially available from a variety of manufactures. The fiber titer is not critical. Similarly, the overall physical dimensional parameters of fabrics are not critical.

Polyetetrafluoroethylene fabrics may thus be treated with the solutions or dispersions of the present invention, which then serve as finishing agents.

The following methods are suitable for fixing the finishing composition to the polytetrafluoroethylene fabric. One is to soak the fabric in a finish, followed by air drying and sintering at the desired temperature at a number of cycles sufficient to achieve the desired coating thickness. To cover large or irregular shapes, spraying the fabric with a finishing agent is used. Sometimes casting the finishing agent on the fabric can be used, and the application of the finishing agent by brush or roller can also be used successfully. In addition, coating bars, knives or skates can be easily used for coating. Typically, the coatings or films are formed to the desired thickness by repeated application, drying and sintering.

The fabric to which the finishing agent is to be applied is cleaned or treated in such a way as to achieve uniform contact with the finishing agent. The fabric may be cleaned by washing in a degreaser or similar solution and then dried. This removes dust or oil from the fabric.

After cleaning, the fabric may be preconditioned by heating or drying under reduced pressure prior to contact with the finish and coating. Preferably, temperatures and pressures in this range are used: a pressure of 2.7 kPa at 110 ° C is sufficient in all cases, but usually heat treatment under mild conditions is sufficient, i.e. at a temperature of the order of about 50 ° C and at atmospheric pressure .

After the pretreatment, the fabric is coated with a finish using any of the above methods. The deposition is carried out in a single step or in several steps, depending on the concentration of the polymer in the finishing agent and the desired coating thickness. .

After use of the conditioning agent, the solvent and / or dispersing medium is removed by any of the methods described above.

The solutions and / or dispersions of the invention can be used to prepare reinforcing agents impregnated or permeated with polymer. These reinforcing means may serve as membrane or sheet carriers. The reinforcing mesh or fabrics may be obtained by dipping, coating or spraying a finishing composition onto the starting mesh or fabrics. The coated mesh or fabric is then fired or sintered to provide good fixation of the fluorinated polymer impregnation. The impregnated mesh or fabric is easier to handle than when not finished.

CS 269 980 B2

Example 6

A copolymer of compounds of formulas CFg and CFg and CF was prepared₂ = CFOCF ^ CF ^ SO ^ F with an equivalent weight of 85О. The procedure is as follows:

78¼ g of a compound of formula CF ^ and CFOCF ^ CFgSO ^ F is added to 4700 g of deoxygenated water containing 25 g of NH4C ^ F ^, 18 * 9 in Na₂HPO ^. 7 ^ 0.15 * 6 g Na1 PO4. H₂0 and 4 g (NH4) 2^WITH2°8 ^for P *^E*^lalcu 1323 kPa of tetrafluoroethylene at 60 ° C for 88 minutes · The reactor is vented under heat and reduced pressure to remove monomer residues. The contents of the reactor are frozen, thawed and washed thoroughly to remove residual salts and soap. After vacuum drying, a finishing solution is prepared by treating 35 g of the polymer produced as described above in a single-row cylindrical Norton porcelain ball lab mill at a speed of 290 min.¹ together and 315 g

1,2-Dibromotetrafluoroethane · Mix in a ball mill at room temperature and atmospheric pressure. The dispersion medium was 10% solids by weight analysis.

To the resulting soft paste was added 300 g of 1,2-dibromotetrafluoroethane and the mill was rotated for a further 3 hours. The resulting dispersion contains 10% by weight of polymer.

From a Prodesoo polytetrafluoroethylene fabric with 24 x 24 leno weave, a disc of about 15 µm diameter is cut and clamped into the frame. The fabric frame is soaked in the finishing composition prepared above. Then, the fabric frame is removed from the finish and its excess is shaken off. · After drying in air, the coated fabric is placed in a muffle furnace where it is maintained at 225 ° C.^C For 1 minute ·

Finished polytetrafluoroethylene fabric It is well penetrated by the finish and has a good feel (as used in textile terminology), compared to a woven fabric prior to finish. removes it from the frame.

Finished polytetrafluoroethylene fabrics produced by the above process Can be used as ion exchange membrane carriers

At present polytetrafluoroethylene fabrics are attached to ion-exchange membranes in the form of a film or foil. Hardly present. According to current practice, fabrics are only deposited in the membranes and do not bond in any way. · Empty voids remain in the fiber and bonding sites.

By using polytetrafluoroethylene fabrics coated with the solutions and / or dispersions of the invention, a closer connection between the carrier polytetrafluoroethylene fabric and the ion exchange membrane can be achieved so that the fabric forms an integral part of the entire structure.

The solution-and / nobo dispersion-woven fabric of the present invention may be bonded to an ion exchange membrane as described in the following example. The same polymer as the membrane-forming polymer or the other polymer may be used for finishing.

Example 7

Following the same procedure as in Example 6, a copolymer of compounds of formulas CF was prepared₂ я CF₂ and CF₂ and CFOCF₂CF₂SO₂F, which has an equivalent weight of 85О.

The finished polytetrafluoroethylene fabric prepared in the same manner as in Example 6 has a good feel compared to the spun fabric prior to finishing.

The finished polytetrafluoroethylene fabric is placed on an ion exchange membrane formed by a film of a vinyl ether-carboxylic acid ester copolymer with tetrafluoroethylene, deposited on a 38.1 µm thick aluminum foil. A silicone rubber sheet abuts the back of the fabric. The assembly is placed between two layers of glass cloth coated on top

CS 269 980 B2 with lytetrafluoroethylene and between the steel plates and the mirror shine and sandwich is pressed for 5 minutes in a heated hydraulic press at 250 ° C with a force of 5. 1 N.

The membrane with the attached polytetrafluoroethylene fabric is placed in a 25% (w / w) aqueous solution of sodium hydroxide at room temperature to remove the aluminum foil. Observation by optical microscope reveals that excellent bonding and excellent adhesion of the polytetrafluoromethylene fabric to the membrane has been achieved. There are no cavities in the formation.

Example 8 has

A copolymer of vinyl ether / vinyl ester of carboxylic acid and totrafluoroethylene, which has an equivalent weight of 84%, is sprayed onto a 10% (w / w) dispersion in the compound BrCF₂CF₂Br. This dispersion is used to coat the aluminum foil. The film is then pressed for 10 minutes¹ N at 25 ° C for 5 minutes. The coated side of the film is then compressed with a force of 2 under the same pressure conditions to a piece of fluorosulfony vinyl ether copolymer having an equivalent weight of 830, having a thickness of 0.1 mm and dimensions of 10 x 10 µm. The fluorosulfonyl side of the film is inverted and a polytetrafluoroethylene fabric that has been coated with a fluorosulfonyl dispersion having an equivalent weight of polymer 850 (10% by weight in the compound of formula BrCF) is deposited thereon.₂CF₂Br). A silicone rubber sheet is adjacent to the back of the polytetrafluoroethylene. The assembly is placed between sheets of polytetrafluoroethylene coated glass fabric and a steel plate with photographic gloss, 4

The whole assembly is pressed for 35 minutes at 25 ° C with a force of 2. The heating is discontinued and the reinforced membrane is removed from the press when the temperature reaches 200 ° C. The membrane is then placed in a 25% (w / w) aqueous sodium hydroxide solution at room temperature to remove the aluminum foil.

Example 9

A portion of the aluminum foil was coated with a carboxylic acid ester copolymer of equivalent weight 856. The carboxylic acid ester copolymer was then coated with a fluorosulfonyl copolyiner of equivalent weight of 85 °. The coated film is placed with the polymer side facing down on the top of a finished polytetrafluoroethylene fabric (Prodesco Ino. 12 x 12, lined weave), which is placed on a vacuum bonded plate. A vacuum source is connected and the sandwich plate is placed under a heated plate at about 250 ° C for about 4 minutes. The polytetrafluoroethylene fabric is firmly bonded to the carrier polymer layer,₄

The solutions and / or dispersions of the invention can also be used for forming polymer films on temporary carriers (removable substrates), and in particular for forming ion exchange membranes on temporary carriers. In these processes, the solution and / or dispersion according to the invention is applied to a temporary carrier and, after removal of the solvent and / or dispersing medium, the resulting film is separated from the carrier. The separation of the carrier can be carried out in various ways, such as chemical etching of the carrier, peeling the carrier from the film, peeling the film from the carrier, and other physical or chemical techniques.

The solutions and / or dispersions according to the invention can also be used to produce bubble-free polynier films having a particularly ion-exchange membrane.

Ion exchange membranes often flow more efficiently when their surface is roughened. This is particularly true when these membranes are used in processes where gas is released in the space adjacent to the membrane. The roughened membranes release gas from their surface so that the membrane does not become clogged with gas. However, the preparation of such roughened membrane surfaces is difficult. By using solutions and / or dispersions, such roughened membrane surfaces can be easily produced.

The solutions and / or dispersions according to the invention can in particular be used to form excellent

CS 269 980 B2 Polymer electrolyte or fuel cell membrane solids with increased bond strength and conductive and catalytic layer bonding * Replicated film surface has fine roughness arrangements for better adhesion to catalyst and conductive parts * This allows for better contact than that achieved on the smooth surface produced by conventional manufacturing technologies ·

Various types of roughened membranes are described, for example, in U.S. Pat. 4 323 4 34, 4 468 301 а 4 3 ^ 9 ^ 22 * ​​Surface irregularities can be created by almost any surface treatment technology such as blasting with aluminum oxide, sand, zirconium oxide or the like, belt sander, vibrating wire brush, chemical etching or Other well known technologies ·

Roughening of the substrate, which serves as a temporary carrier, is carried out either by spraying its surface or by etching it to the desired degree of roughening. Roughening of the polymer film (membrane surface) is then achieved by adapting the polymer to the roughened surface of the substrate.

Roughening of the membrane surface may be accomplished by first depositing the particles in the roughened substrate. These particles may not be bent in the substrate, and when later used in the formation of polymer films, they may become part of the film. In this way, membranes having bubbles-releasing particles on their surface can be easily obtained.

The roughened surface to which the solution or dispersion of the invention is applied is prepared and the solvent or dispersion medium is removed from the polymer film adapted to the roughened surface. If desired, the polymer film and substrate can be processed by melting, sintering or pressing. The film can then be separated from the substrate by well-known physical or chemical technologies.

As the substrate to which the solution and / or dispersion of the present invention can be applied, any roughened surface substrate, such as nobo plate sheets made of metal such as aluminum, glass, wood or other polymers can be used.

The substrate to which the dispersion is to be applied may optionally be cleaned or treated in the above-mentioned manner in order to achieve uniform contact with the solution and / or dispersion of the invention.

Various techniques can be used to separate the continuous film formed on the substrate, such as by chemical etching of the substrate, evaporating the substrate, dissolving it, peeling the substrate from the film, peeling the film from the substrate, and the like.

In this way, films of different thicknesses can easily be produced.

Example 10

A 0.05 mm thick, stretched aluminum foil is treated with alumina particles (grit ЗОО) to impart an irregular, sharp edge to the aluminum foil. After this processing, some parts will remain in the foil ·

The aluminum foil treated as described above is coated with a viscous dispersion prepared as described in Example 4. '

The coating is melted at 25 ° C for five minutes · The deposition cycle is repeated as many times as possible until a film thickness of 0.02 mm is reached on the film.

The coated side of the foil is placed against a 0.1 mm thick film of polymer having an equivalent weight of 65 °, prepared as described in Example 6.

The dried polymer is then extruded at 20 to 288 ° C using a Haake Rheomex 254 stainless steel screw extruder and a 15 cm extrusion die. Extrusion nozzle

CS 269 980 B2 has a slot of 0.5%. Final drawing yields a film having a thickness of 0.1 to 0.13 mm, which is cooled on an unheated stainless steel roll. Film samples are cleaned by degreasing with acetone and air dried.

The coated aluminum foil and film thus produced are placed between two sheets of glass fabric coated with polytetrafluorothylene and the entire assembly is placed between two photographic gloss plates. The composite sandwich is pressed for 5 minutes at a pressure of 5512 kPa and a temperature of 25 ° C in a heated hydraulic press. The film composite film is then removed from the press and placed in a water bath of 25% (w / w) sodium hydroxide at 70 ° C for 4 hours to remove the film and hydrolyze the film. The membrane film is now in sodium form and is suitable for use in a chloroalkali cell with a minimum gap filled with brine.

Inspection of the surface by an optical microscope shows finely structured irregularities with sharp points and a certain number of debris particles adhering to the places where they remain after the film has peeled off.

The resulting ion exchange membrane was tested in a chloralkaline test cell formed for this purpose. The cell has an exposed electrode surface of 56 cm⁴ and comprising a titanium anode compartment and a plexiglass cathode compartment. The anode is a metal mesh electrode coated with ruthenium oxide. The cathode has an electrocatalyst surface. In operation, when a current of DC current relative to the electrode surface of 0.3 A / cm is passed through the electrodes, a sodium chloride solution containing 20% ​​by weight of NaCl is introduced into the anode compartment and water is added to the cathode compartment. The membrane is placed between the electrodes and screwed between two cell halves, each containing a gas outlet and an overflow. The membrane works well in a test chloralkali cell.

The solutions and / or dispersions according to the invention can be used in the production of composite polymer films and in particular in the production of ion exchange membranes.

when the polymers of each layer may contain standing or divergent groups, the most preferred are those composite films in which the single-layer polymer comprises a Y-labeling group of the formula -SO₂F and the second layer polymer comprises a Y-labeling group of the formula

The term composite film as used herein refers to a film consisting of two or more different polymers. These polymers may be of different types or may have different concentrations of sites convertible into ion exchange groups. These different polymers are located in layers parallel to the film surface. The second polymorphic film may comprise ion exchange sites or sites convertible into such ion exchange sites. However, the polymer used to prepare the solution and / or dispersion according to the invention should not contain ionoxic sites, but should contain sites convertible thereto.

The first polymorphic coating applied from the solution and / or noble dispersion according to the invention can be fixed to another polymer film by sintering or pressing.

The following methods are suitable for fixing the polymer from the solution or dispersion of the present invention to a second polymer film. Dipping the second polymer film in solution or dispersion, then air drying and sintering at the desired temperature with sufficient repetitions of the cycle to achieve the desired thickness. Solution spraying is preferably used to cover large or irregular shapes. Sometimes pouring a solution or dispersion onto a second polymer film is used. Painting the solution or dispersion with a brush or roller is also successfully used. In addition, the coating can readily be carried out using a knife or skate. Usually, coatings or films achieve the desired thickness by repeated drying and sintering.

The second polymorphic film to which the solution or suspension is to be applied is cleaned or processed in such a way as to ensure uniform contact with the solution or dispersion. It can be cleaned by washing with a degreaser or solvent and then dried. Cleaning up

WITH,.

monitors the removal of dust or oil.

CS 269 980 B2

After cleaning, the second polymer film may be pretreated by heating or drying under reduced pressure before contacting the solution and / or dispersion of the invention.

After pretreatment, the second polymer film is coated with a solution and / or dispersion according to the invention, wherein the solvent and / or dispersing medium is removed according to the procedures described above.

In this way, composite films of different layer thicknesses can be easily produced. When in ionic form, such films are particularly suitable as membranes in electrochemical cells for the electrolysis of sodium chloride solutions to form chlorine gas and sodium hydroxide solutions. The membranes prepared in this way have surprisingly good current properties when used in such chlor-alkali materials.

Example 11

A film of Example 4 is prepared having an equivalent weight of 974.

A dispersion of a carboxylic acid ester polymer with an equivalent weight of 856 is prepared by mixing 49 g of this polymer with 307 g of 1,2-dibromotetrafluoroethylene. The dispersion is used to coat the film prepared by the above-mentioned method of dipping. The coated film was pressed for 5 minutes in a heated press at a pressure of 2756 kPa and a temperature of 25 ° C between glass-fiber-reinforced polytetrafluoroethylene cover sheets, the entire assembly being placed between photographic gloss steel plates.

The coversheets were removed and the composite film was hydrolyzed in 25% (w / w) aqueous sodium hydroxide solution for 4 hours.

The composite membrane is placed in a chloro-alkaline cell wherein the carboxyl polymer is a giant. into the cathode compartment. The membrane works well during operation.

The solutions and / or dispersions of the invention can be used to produce composite films using temporary carrier (removable substrate) technology.

After the polymer from the dispersion has been fixed to the substrate, it contacts the substrate with a second dispersion formed in the same manner as the first dispersion. Thereafter, the polymer deposited from the second dispersion is melted to form a second film and this can be joined to the first film. After the second film has been formed, the two films flow to each other while heating under pressure to bond the two films together. The temperature of this bonding is from 150 to 380 ° C and the pressure is usually about 12 780 kPa. The time is 10 seconds to 120 minutes.

The removable substrate can be removed by various techniques as described above.

The stages of final heating and lopon may optionally be combined into an iodine coordinated operation, instead of being performed separately. That is, the second film can be formed and melted during melting to the first film.

Example 12

Prepares a copolymer of compounds of formulas CF ^ = CF ^ and СГ '₂ = CF0CF_nCF_OC00CH3, proceeding as follows:

g of a compound of formula CF₂ with CFOCF 2 CF 3 COOCH 2 was added to 250 g of deoxygenated water containing 3 K NH 4 CC 4 1.5 8 Na 2 PO 4. 7 »₂0 and 1.0 g Na 2 PO 4. HgO in glass reactor with stirring at 800 rpm '¹. 50 ml of deoxygenated water containing obsahuje / ^ g (NH ^) are then injected into the rooster.₂The reactor was kept under a positive pressure of 1516 kPa of tetrafluoroethylene at 50 ° C for 180 minutes. The reactor is vented and the contents are acidified with 50 ml of 6N hydrochloric acid to coagulate the latex and to exclude the polymer from the emulsion. The polymer is filtered off, washed extensively to remove inorganics, soap and monomer residues, and then vacuum dried at 85 ° C for 16 hours. Dry

CS 2 9 980 B2 polymer has a weight of 99.2 g. By titration it is found that its equivalent weight is 856.

By mixing about 49 g of polymer with about 304 g of 1,2-dibromotetrafluoroethane, a dispersion of a carboxylic acid ester polymer with an equivalent weight of 856 is produced.

A polymer having an equivalent weight of 85 ° C was prepared as described in Example 6.

A second dispersion was formed from 30 g of polymer using 270 g of 1,2-dibromotetrafluoroethane. The aluminum foil was coated with the dispersion and heated to 300 ° C for 1 minute. The coating and heating steps were repeated until a coating thickness of 0.1 mm was achieved.

A piece of aluminum foil was coated with a dispersion of a carboxylic acid ester copolymer with an equivalent weight of 856. The dispersion medium was allowed to air dry and the coated foil was melted for 1 minute at 250 ° C between two sheets of an inclined fabric coated with polytetrafluoroethylene. The process is repeated to form a 0.025 nun film. The film of the carboxylic acid ester copolymer film on the film is then coated in a similar manner with a fluorosulfonyl copolymer dispersion having an equivalent weight of 85О to form a fluorosulfonyl copolymer film until an overall thickness of the composite film consisting of the two films is 0.13 mm. The coated foil is placed polymer side down on the face side of a finished polished-tetrafluoroethylene fabric (Prodesco Tne., 12 x 12 leno-woven fabric), which itself places on a suction plate. A vacuum source is connected and the plate is placed under a heated plate at 25 ° C for 4 minutes. The polytetrafluoroethylene fabric is firmly adhered to the polymer backing layer.

The solutions and / or dispersions according to the invention may also be used in the following manner:

After applying the first dispersion to the first substrate and the second dispersion to the second substrate, the deposits can be pressed together to form a melted composite film. In this process, the substances will tend to mix.

After the polymers have been applied to the respective substrates, they are brought into contact with each other at a temperature, pressure and time sufficient to bond the polymers together. Such a temperature is usually from 150 to 380 ° C. The pressure is preferably up to 1380 kPa and the time is from 10 seconds to 120 minutes.

Subsequently, the substrates are removed by various methods as described above.

In this way, composite films with different layer thicknesses can easily be produced.

Example 13

Using the procedure of Example 6, a first polymer having an equivalent weight of 85 ° C is produced.

A dispersion is prepared from 30 g of the first polymer using 270 g of 1,2-dibromototrafluoroethane. The dispersion is applied to an aluminum foil and heated to 3 ° C for 1 minute. The coating and heating steps are repeated until a coating thickness of 0.1 mm is achieved.

A second copolymer is then prepared according to the procedure of Example 2. It is a copolymer of compounds of samples CF 4 = CF 8 and CF₂ After the polymorph is dried under reduced pressure, a second dispersion is prepared by contacting 56 g of polymer in a Norton porcelain ball mill with 168 g of 1,2-dibromotetrafl. .uoroethane. The mixture is stirred in a ball mill overnight at room temperature and atmospheric pressure,

300 g of 1,2-dibromotetrafluorothane are added to the resulting soft paste, and the mixture is rolled in the mill for a further 3 hours. The resulting dispersion contains 12.5% ​​by weight of polymer. The mixture is coated with a 0.95 mm thick sheet of aluminum foil shaped into an envelope or pocket by immersing it in the dispersion. The coated aluminum foil is allowed to air dry. The dispersing medium is evaporated from the dispensers at room temperature.

CS 269 980 B2

The aluminum foil coated with the second copolymer is heated to 300 ° C in a muffle furnace for an iodine minute to melt the polymer to form a more uniform film.

The resulting film is continuous and has a thickness of 12.7

The soaking and heating prooes are repeated five times until a second polymer is formed.

The two coated films mentioned above are then pressed together with the coated side to the coated side, at a temperature of 300 ° C and an overpressure of 2.776 kPa over 3 minutes. The resulting two-layer composite membrane is hydrolyzed with a 25% (w / w) aqueous sodium hydroxide solution. The membrane works satisfactorily in a chlorine-alkaline test cell. »»