Dynamic membranes for reverse osmosis

ABSTRACT OF_THE DISCLOSURE

The invention relates to thin and minute foils of a synthetic material obtained by interfacial polycondensation

ץ of a compound B and a compound A. Basically a non-aqueous phase in which compound B is dissolved is dispersed in water in which compound A is dissolved. After the polycondensation has taken place, the result is a dispersion of the non-aqueous phase surrounded by the polymer in water. Then the dispersion is heated above the boiling point of the non-aqueous phase but below that of water. The thin minute and sdid foils may be used directly or after some purification treatment for the formation of a dynamic membrane.

1. Introduction

Dynamic membranes are used in the purifications of liquids especially in the demineralisation?; of water.

They essentially consist in the first place of .a microporous continuous structure such as ceramic material, sintered metal material and the like. If liquids are pressed through such a microporous continuous structure, scarcely any impurity is held back/ It has therefore been proposed in the second place to cover said microporous structure by a thin layer of discrete particles. It is noted that these particles have dimensions which in all directions are of the same order of magnitude. The combination of microporous structure and layer of particles is called dynamic membrane.

If a liquid flows through such a dynamic membrane a part of the impurities are held back and a part traverses the dynamic membrane. linger 100 parts of impurities present in the original liquid, say 70 parts are retained and only 30 parts traverse the membrane it is said that the retention factor R is 70%. It is obvious that the higher R is the better the removal of impurities i.e. the less impurities, such as minerals, are found in the effluent that has passed’ through the dynamic membrane e.g. as water. But this calls for a very fine microporous structure and a very evenly distributed layer of the discrete particles

43783/2 which covers the micrpporous structure, such a struc^^e means that the dynamic membrane offers a high flow resistance so 9 that in order to obtain a reasonable amount of the effluent the pressure drop across the membrane should be high. The amount of purified liquid is expressed by F = flux which is

2 measured in m /m /sec that is the volume of effluent per area of dynamic membrane per second.

Although the principle of the dynamic membrane is such that it can generally be used to remove impurities in any liquid a well-known use is to demineralise water and more specifically to desalinate water. The general use of a dynamic membrane is then called reverse osmosis. A high retention factor R indicates that the effluent, for example water, contains as small amount of minerals as possible.

An attractive feature of reverse osmosis with a dynamic membrane is that if, for one cause or another, the dynamic membrane gets blocked, that it if the flux F is becoming low, one may for a moment reverse the direction of flow of the liquid from the effluent side to the original side. The particles are blown away from the microporous structure and whirl in the original liquid. If necessary fresh particles are added to the original liquid. If then the flow of the liquid is again reversed the particles settle down on the microporous structure and the dynamic membrane will again function as usual.

A convenient way to build up a dynamic membrane is to have one side of the microporous structure in contact with the liquid to be purified then to disperse the particles in this liquid or to add a dispersion of the particles to the liquid, and finally to put pressure on this liquid. The .liquid starts to flow through the porous structure, taking the particles to the openings of the microporous structure, and in this way the dynamic membrane is formed.

The nature of the microporous structure is not־ an important feature of the present invention. Of course, the structure and the discrete particles should not dissolve in the liquid. The particles may consist of an inert material or may be made of an ion exchanging material.

The form of discrete particles is not of great importance. They should seal the miropores but it is not necessary that the > particles have dimensions of the same order of magnitude in all dire^ tions. Moreover, discrete particles are rigid and therefore they do not optimally seal the micropores.

It is preferred that the discrete particles are replaced by thin foils. ' Such foils have a structure so that one dimension of the foils is much smaller than the other two dimensions. However, the two larger dimensions should be such that micropores are sealed. During reverse osmosis such a dynamic membrane offers much less resistance to the flow of the liquid so that the normal flux is attained at a lower pressure, in other words, if pressures are the same as usual the flux of this type of dynamic membrane is higher than that of the type with the discrete particles which are more or less spherical.

Such dynamic membranes have a quite acceptable retention factor.

By means of the present invention, it is possible to make synthetic foils for use in dynamic membranes, and the process is sufficiently flexible to produce foils which can be tailored to a specific use. _x

According to the invention there is provided.a process for : . making thin polymer foils for use in a dynamic membrane which comprises the steps of (i) dispersing in water a non-aqueous liquid phase, immiscible with water and having a boiling-point below that of water, which phase contains a substantially water-insoluble polymerization reactant B (ii) adding an aqueous solution of a polymerization reactant A, which results in a polymer forming at the interface of the non-aqueous phase and the water, said polymer encapsulating the non-aqueous phase: and (iii) heating the dispersion to a temperature above the boilingpoint of the non-aqueous phase but below the boiling-point of water, so as to rupture the encapsulating polymer to form a dispersion of thin polymer foils, and to evaporate the non-aqueous phase.

If desired, the thin foils can be filtered and redispersed in water.

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There are a number of procedures, differing very little from each other, which attain the objective desired. As will appear from the scheme of Figure 1, the process of the invention occurs in two stages. In stage, a the interfacial polymerisation reaction takes place and a non-aqueous phase encapsulated by polymer is obtained.

This can be implemented in the fwo following ways:

Method I: A non-aqueous (usually organic) solution of reactant B, is dispersed in water. Depending on the nature of the interfacial polymerisation reaction to be implemented, an acid acceptor or a buffer can be addedto the dispersion.

Kinetic and catalytic aspects here determine type and pH range.

To promote dispersion, a surface active compound cart be used, if desired.

Then an aqueous solution of co-reactant A is added to the dispersion. To control the polymerisation reaction conditions, a buffer or acid acceptor and/or surface active compound may have been added tdothis d'queous^solutiohuOfcreacstantcA.'Qt a:

Now a reaction will take place at the interface of the water and the non-aqueous solvent.

Method II: In this method a non-aqueous (usually organic) solution Of reactant B, is dispersed in waier, in which reactant A has previously been dissolved. Depending on the nature of the interfacial polymerisation reaction, an acid acceptor or buffer can be added. In this case, however, the said acceptor or buffer is added before the preparation of the dispersion.

To promote dispersion, a surface active compound can be used, if desired.

Now the reaction will take place at the interface of the water and the non-aqueous solvent.

In stage β, the encapsulated non-aqueous phase obtained in stage a is prepared to be brought into the reverse osmosis apparatus by one of the following methods.

Method 1: The non-aqueous phase, which is encapsulated by the polymer, and which, has a boiling-point below that of water, is evaporated by hpating the dispersion obtained in stage a to a temperature between the boiling-points of water and the non-aqueous phase.

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In doing so, the spherical polymer foils formed in stage a burst open and the aqueous dispersion of polymer foils thus obtained is immediately brought into the reverse osmosis apparatus. In the process, the buffer or acid acceptor and surface active compound used, if any, are brought into the reverse osmosis apparatus.

Method 2: The buffer or acid acceptor and surface active compound used, if any, are removed from the aqueous dispersion of polymer foils obtained in method 1 by filtering and washing, before the polymer foils are brought into the reverse osmosis apparatus.

After having redispersed the purified polymer foils in water, the dispersion is brought into the reverse osmosis apparatus. It may be necessary, to promote redispersing, by adding again a surface active compound.

Method 3: The dispersion in water of non-aqueous phase encapsulated by polymer obtained in stage a is first filtered and washed in order to remove residue of reactant and buffer or acid acceptor and surface active compound added, if any.

The material thus obtained, consisting of non-aqueous phase encapsulated by polymer, is again taken up in water.

Now as in method 1 the non-aqueous phase is evaporated and the product obtained is !mediately brought into the reverse osmosis apparatus.

When the above product is again taken up in water, new buffer material or a new acid acceptor can be added, if desired« It may moreover be necessary to add again surface active compound.

Method 4: As in method 3 the non-aqueous phase is first filtered and taken up again in water, before it is evaporated. The same observations are ipSe in method 3 regarding the addition of buffers, acid acceptors and surface active compound.

After evaporation the material is not immediately brought into the reverse osmosis apparatus, but as in method 2 a f11traticm is first carried out. After washing and redispersing the foils in water, the residue is brought into the reverse osmosis apparatus. When redispersing, it may be necessary again to add surface active compound.

The above described scheme is illustrated in Figure 1.

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The numerals 1- 4 inclusive at the bottom of Figure 1 indicate the four methods for getting from the dispersion to the dynamic membrane. Stage a is indicated by steps K, M and N or steps L and N. Stage β is indicated by steps 0ן and Q.]; 0!, R׳| and Q2^: °2 an^d P, 02» ^R2 Q4. These steps are more fully described below.

Method 1 encompasses steps K, M and N. . K means that the non-aqueous phase, in which reactant B is dissolved', is dispersed in water. Compounds useful for preparing'dispersions, such as buffers, acid . acceptors, surface active compounds and the like, ־may also be dissolved in the water. K is followed by .M, namely the addition of a water solution of . reactant A to the dispersion formed in step K. The 'water solution of reactant A may also contain auxiliary'! compounds ;.if desired.Steps;Kgz1d,.Mlea(i io.^ U which describes the non-aqueous phase which is encapsulated by the polymer. The droplets of the non-aqueous phase enveloped by the polymer are formed by the reaction between reactants A and B. These droplets are in the form of a dispersion in water.

Method II encompasses steps L and N. 1 means that the non-aqueous solution of reactant B is dispersed in water in which reactant A is dissolved. Step L results in N which is described, above.

From N, one can use methods 1-4 described above to obtain the dynamic membrane. Method 1 is described by stepsן0׳ and . According to 0ן, one ־'? may evaporate the non-aqueous phase immediately by heating the dispersion obtained in step N to a temperature above the boiling point of the nonaqueous phase but below the boiling point of water. Step 0ן results in the rupture of the encapsulated , non-aqueous phase and the formation of a multitude of small thin foils. These foils are still dispersed in water and they may be used immediately .

: in the reverse osmosis apparatus (Step Q-j) .

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Method 2 is described by steps 0ן, Rj and Qg. According to step R!, the thin polymer foils obtained in step 0ן are washed and redispersed in water. The purified foils are then brought into the^reverse osmosis apparatus (Step Q2).

Method J is described by steps P, Og and Qj. In step P, the droplets of encapsulated non-aqeuous phase formed in step N are first filtered and then taken up.again in water. According to step 02, the dispersion obtained by step P is then heated to a temperature above the boiling point of the non-aqueous phase but below the boiling point of water. Step Og results in the rupture of the encapsulated non-aqueous phase, the evaporation of the non-aqueous solvent, and the formation of the polymer foils. The dispersion of th .in foils formed in step 02 may be immediately brought into thboreVersetosmosifSirapparatus-i^Stept-Qjr) p¹׳ - Method 4 is described by steps P, 02» R2 Q4. Steps P and 02 are described above. According to step R2, the thin polymer foils obtained in step 02 are filtered, washed and redispersed in water. The purified thin foils are then brought -into the reverse osmosis apparatus (Step Q4).

All the polymerisation reactions have been carried out at room temperatures but deviations are a־ 1־inwed provided the boiling point of the non-aqueous 'phase is not surpassed.

Dispersion can be accomplished in a number of known ways, for instance, by mechanical means such as stirring, or by ultrasonic means. Also, a gas .

can be passed through both phases. In general ghaking does not lead to a good, dispersion unless specially designed apparatus is used.

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3. Types of interfacial polycondensation products

3.1 Linear polymers

<td> No.</td><td> Product name</td><td> Reactant A water phase</td><td> Reactant B non-aqueous phase</td>

<td> 1</td><td> polyamide</td><td> diamine</td><td> dicarboxylic acid chloride</td>

<td> 2</td><td> polyoxamide</td><td> diamine</td><td> oxalylchloride</td>

<td> 3</td><td> polyurea</td><td> diamine</td><td> phosgene</td>

<td></td><td></td><td> diamine</td><td> dicarbamyl chloride</td>

<td></td><td></td><td> diamine</td><td> diisocyanate</td>

<td> '+ '</td><td> ־polybisurea</td><td> hydrazine</td><td> diisocyanate</td>

<td> 5</td><td> polyurethane</td><td> diamine</td><td> di (chloro formate)</td>

<td></td><td></td><td> diol</td><td> diisocyanate</td>

<td> 6</td><td> polyester</td><td> diol</td><td> di carboxylic acid chloride</td>

<td> 7</td><td> polybisester</td><td> diol</td><td> oxalyl chloride</td>

<td> 8</td><td> polycarbonate</td><td> diol</td><td> di (chloro formate)</td>

<td></td><td></td><td> diol</td><td> phosgene</td>

<td> 9</td><td> polymono’acylhydrazine</td><td> dihydrazine</td><td> dicarboxylic acid chloride</td>

<td> 10</td><td> polydi acylhydrazine</td><td> dihydrazide</td><td> dicarboxylic acid .chloride</td>

<td></td><td></td><td> hydrazine</td><td> dicarboxylic acid chloride</td>

<td></td><td colspan="2"> polybisdiacylhydrazine oxalic acid dihydrazide</td><td> dicarboxylic acid chloride</td>

<td> 12</td><td> poly'semi carbazide</td><td> dihydrazine</td><td> diisoc.yanate</td>

<td> 13</td><td> polyacylsemi carbazide</td><td> dihydrazide</td><td> diisocyanate</td>

<td> 14</td><td> polybi sacylsemicarbazide</td><td> oxalic acid dihydrazide</td><td> diisocyanate</td>

<td> 15</td><td> polyurethaneacylsemicarbazide</td><td> hydroxyacylhydrazine</td><td> dii socyanate</td>

<td> (One</td><td> of both or both amino</td><td> groups may also</td><td> be secondary amino</td>

<td colspan="3"> groups such e.g.־ in piperazine).</td><td></td>

<td></td><td> The last reaction,</td><td colspan="2"> no. 15, gives an example of a polyme:</td>

with two different chains between organic groups R and R', viz. the urethane group (see no.5) and the acylsemicarbazide group (see no.13).

/ A

43783/2 φAn infinite number of such polymers can be synthesized, but the following categories can be stated:

a. alternating copolymers (such as in reaction No.15)

b. random copolymers

c. blade copolymers

These categories can be manufactured in the known ways, re.b. by adding more than one reactant in one or two phases, recc. by starting fromxrepolynierized reactants with a low degree of polymerisation.

3.2. Crosslinked polymers

When one of the two ar both reactants have more than two functional groups, a crosslinked polymer is produced by means of the interfacial polycondensation reaction.

In that case the same scheme, as given in section 3.1, can be applied for this category of interfacial polycondensation reactions, giving rise to encapsulation having a threedimensional structure at the molecular seals.

For the group of crosslinked polyamides some examples are given as follows:

An example is that reactant A is 3,3*-diaminobenzidine and reactant B is terephthaloyl chloride. The product is shown in Figure 2.

Other examples are the formation of the product shown in Figure 3 from 4,4''־diamino-diphenylamine and terephthaloyl chloride and the product shown in Figure 4 from 2,4-diamlnodiphenylamine as reactant A and terephthaloyl chloride as reactant B.

Such an extension to non-linear products can be applied to all types of reactions specified in section 3.1»

Thus the compounds of the type of diols SOS. 5 to 8 can be extended with polyols such as monosaccharides (e.g.glucose), disaccharides (e.g. sucrose), polyhydroxybenzenes (e.g. phlorogluainol) and the like.

The reaction of such polyols with a diisocyanate produces polyols having intricate crosslinked structures containing urethane groups in a repetitive chain (see section 3.1. reaction 5). Such a chain is

- —r - 0 — CO — NH — R״ - NH - C00-|in which R and R’ represent organic groups as deAned more fully further below.

3.3 Autopolymerization diisocyanates

In several of the syntheses mentioned in section 3.1 use is

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I made of a diisocyanate as the reactant. _%

Diisocyanates, such as for example the dicarboxylic acid chlorides, undergo a hydrolysis which is less favourable for the polycondensation reaction (side reaction):

= C = N - R- N = C = 0 + 2H₂0 Η_£Ν - R - NH₂ + 2C0₂

So, the product of this hydrolysis is a diamine and in section 1 it has been stated that the reaction between a diisocyanate and a diamine yields a polyurea as product.

So, this hydrolysis provides a way of implementing interfacial polymerization with one reactant as starting material .For this purpose a solution of the diisocyanate in the organרn solvent is dispersed in water.

At the interface of the two phases the following reactions occurtjwu’i

H2N-R-NH2 + 2C0₂-R-NH-CO-NH-

1. 0 = C = N-R-N = C = 0 + 2H₂0

2. 0 = C = N- R- N = C = 0 + H₂N-R-NH₂ 'יי This interfacial polymerization reaction takes place in the same way as described in Methods 1 to 4» described abdve, as regards the rest of the details.

The selective permeable qualities of a membrane material are largely determined by the capacity of the material to bind water by means of hydrogen bridge linkages.

The types of chain units between the organic groups R and R’, mentioned above in section 2, should have certain properties required for promoting such hydrogen linkages. However, if such a type of hydrogen linkage is to function correctly, the organic groups R and R' also have to meet certain requirements.

Preferably, the reactant A in the water phase is a compound of the,general formula wherein p is 0 or 1 .and n is.>2 when p is 1 and is 2 when p is 0, X represents -NH₂, >NH, -NHZ, -OH, -NHNHg, >N-NHp, -CO-NH-NHg, wherein. Z represents a lower alkyl group, or an aromatic ring having up to 6 carbon atoms, R represents an aromatic ring, two condensed aromatic rings, or two aromatic rings linked together by a group selected from - CHp -, -SOp-, -00-, -NH-, -S-,

-NCH^- or >CHOH, each aromatic. ring having up to 6 carbon atoms, any of such >NH or -CHOH linking groups, as having reactive groups, being counted as an X group.

If p = 1 and n = 2, reactant A will give rise to linear polymer reaction products.

If p = 1 and n > 2, a crosslinking polymer reaction will occur.

In a polymerization reaction involving reactant A, the group X is the reactive group and R is the hrganic \ group.

If a > NH group is incorporated in the nucleus of group R, it also acts as a reactive group, i.e. a group \ involved in the polymerization reaction.

If R is piperazine, it reacts as the alicyclic form containing two>NH groups, and this also occurs if R is two aromatic rings coupled by a > NH group or a >CHOH group. Therefore, if e.g. RX₂ is 4,4’ - diaminodiphenylamine, a crosslinked polymer will be produced.

When p = 0 and n = 2, reactant A is preferably hydrazine or oxalyldihydrazine (then R being replaced by a hydrogen atom or a carbon-carbon linkage).

Preferably, reactant B in the non-aqueous phase” is;a substantially water insoluble compound having the general formula R' Y , wherein Y is -00-01, -NH-C0-C1, -N =0 =0, or q m^׳

-C0-C1, R^J represents an aromatic ring» ;־two condensed aromatic rings or two aromatic rings linked by a methylene group, each aromatic ring containing up to 6 carbon atoms, q is 1, and m is at least 2. . χ

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Alternatively, q may be 0 in which case R' is replaced by an atom-atom linkage in the formula of reactant B, and m is 2. One of the values of Y may then be Cl thus making reactant B phosgene.

The values^ of p and q in reactants A and B cannot both simultaneously be zero, and this means that a polymeric compound formed by reacting A and B must always contain a repetition of chain units comprising an organocyclic ring.

The organic groups R and R' mentioned above may be provided with preferably non-ionic substituent's with up to seven atoms including the hydrogen atoms.

In total, no more than two substituents are allowed per cyclic nucleus.

One or two ionic substituents may be present in R and R' but preferably should be avoided.

All these reactants for producing interfacial polymerization are known^as are the conditions of concentration, temperature and additions which are necessary to obtain good interfacial polymers.

The polymer produced by the interfacial, polymerization reaction should meet the following requirements:

It must not show a very high degree of intermolecular interaction;

The degree.of polymerization must be such that the ¹material is able to form a film.

The material obtained must not be soluble in water, nor in the non-aqueous solvent used in its preparation.

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Substituents

All organic groups R and R* may contain substituents preferably non-ionic substituents with up to seven atoms including hydrogen atoms.

In total no mor« than two substituents are allowed per alicyclic or aromatic nucleus.

Ionic substituents are allowed only in a very small percentage and preferably should be avoided.

All these reactants for producing interfacial polymerization are known in the art as are the conditions 0f concentration, temperature and additions which are necessary to obtain good interfacial polymers.

5. The polymer as a whole.

The polymer as a whole has to meet the following requirements:

- It must not show a very high degree of intermolecular interaction;

- The degree of polymerization must be such that the material is able to form a film.

- The material must not be soluble in water, nor in the nonaqueous solvent used in its preparation.

6. Kon-aqueons solvents

The non-aqueous solvents used in the interfacial polycondensation reactions has to meet the following requirements:

- The boiling point mast be lower than that of water, under the prevailing circumstances.

- It:must not be significantly miscible with water.

- The polymer formed must neither dissolve in, nor highly swell under the influence of the solvent.

The followings solvents are particularly appropriate:

<td> Solvent</td><td> boiling-point *C</td><td> Solubility in g/100cc water</td>

<td> hexane</td><td> 69.0</td><td> 0,0138 (15,5*0</td>

<td> benzene</td><td> 80.1</td><td> 0.082 {22.Ο</td>

<td> carbohj^etrachloride</td><td> 76.8</td><td> 0.08 (20*C)</td>

<td> cyclohexane</td><td> 81.4</td><td> insoluble</td>

<td> 1-hexene</td><td> 63.5</td><td> insoluble</td>

<td> pentane</td><td> 36.2</td><td> 0.036 (16*0</td>

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<img file="IL43783A_D0001.tif" />

<td> solvent</td><td> boiling-point °C</td><td> solubility wate</td>

<td> 1-pentane</td><td> 30.0</td><td> insoluble</td>

<td> cyclopentene</td><td> 44.2</td><td> insoluble</td>

<td> chloroform</td><td> 61.3</td><td> (°0ל1) 1.0</td>

<td> 1,1-dichloroethylene</td><td> 37</td><td> insoluble</td>

<td> 1,2-dichloroethylene</td><td> 60.1(c^s),48.4(tri</td><td> xns) insoluble</td>

<td> trichloroethylene</td><td> 87 </td><td> 0.1</td>

<td> diisopropylether</td><td> 69</td><td> 0,2</td>

<td> furan</td><td> 32 .</td><td> 1</td>

7. Acid acceptors

In case an acid (mostly HC1) is released in the polycondensation an acid acceptor is desired, in order to reach a sufficiently high degree of polymerization.

It is necessary that the acid acceptor reacts only slightly or not at all with the reactants. Otherwise the acid acceptor would act to a high degree as a terminator in the polymerization reaction. For this reason, the term acid acceptor, when applied to amines, which.are also . known to be acid acceptors, is limited to mean the tertiary amines.

As an acid acceptor for example the following bases can be used:

<td> NaOH</td><td> NaHC0₃</td><td> Na₂C0</td>

<td> Na-acetate</td><td> Na₂S</td><td> Borax</td>

<td> KOH</td><td> k₂co₃</td><td> CaCO₃</td>

<td> MgO</td><td> Ca(OH) ₂</td><td></td>

Tertiary amines, e.g. (^C2^H5^3^N

Quaternary ammonium bases.

8. Buffer systems

In some cases it may be necessary to maintain a constant pH during the interfacial polymerization, so that a buffer must be used instead of only an acid acceptor. This is e.g. the case with reactions between aromatic polyamines, such as e.g. diaminobenzene, and acid chlorides, to form polyurea.

These reactions do not proceed very well with a basic acid acceptor, but they do in an acid medium. Then acid catalyses the reaction. On the other hand, the milieu must not become too acidic, because then the amine is practically completely protonated (-NH₂ —/ -NH₃+) so that no reaction takes place any longer,

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So there is an optimum pH for the reaction and this must be maintained with a buffer. In some cases the amine itself, provided it is present in sufficient surplus, can be used as the basic component of the buffer.

Some examples of useful buffers:

<td> \acid component</td><td> basic component</td><td> pH range</td>

<td> oxalic acid</td><td> oxalate</td><td> 1-1.5</td>

<td> o-phosphoric acid</td><td> dihydrophosphate</td><td> 1.9 - 2.4</td>

<td> formic acid</td><td> formate</td><td> 3.5.- 4.0</td>

<td> acetic acid</td><td> acetate</td><td> 4.5 - 5.0</td>

<td> hydrophthalate</td><td> phthalate '</td><td> 5.8 ־ 5.3</td>

<td> hydrophosphate</td><td> phosphate</td><td> 7.0 - 7.5</td>

<td> hydrochloric acid</td><td> . borax</td><td> 8.0 - 9.0</td>

For a sufficiently great buffer capacity a minimum quantity of the buffer compounds, depending on the reactant concentrations, is required. In some cases the choice of the t^uffer-־ fomponentsLis also determined by the solubility bu. of a certain buffer system.

9. Surface active substances

Surface active compounds can be added to the reaction medium to attain a better dispersion of the non-aqueous phase into the aqueous'phase. Here, too, it is required that these compounds must not react with one of the reactants. Examples of the surface active compounds which may be used: Surface active compounds:

sodium laurylsulphate sodium oleate hexadecyltrimethyl ammoniumbromide hexadecylpyridine chloride dialkylsulphates

The conditions with regard to the use of solvents, acid acceptors, buffers, surfactants are again known per se.

10. Examples of possible reactant combinations

For the examples the same order will b^maintained as stated in the Table of section 3.1. group 1. polyamides a diamines Caqueous phase) diamine

1,3-diamino benzene

Λ

1.4- diamino benzene

2.4- diaminotoluene

2.5- diaminotoluene

2.6- diaminotolueae .,.

3-ethyl-m-phenylenediamine

4.6- dimethyl-m-phenylenediamine

2,4-diamino anisol

2,5־diamino-nitrobenzene

2.6- diaminopyridine benzidine

3,3'- dimethyl-benzidine

3,3¹-dimethoxybenzidine piperazine

2-methylpiperazine trans-2,5-dimethylpi perazine cis-2., 6-dimethylpi perazine 2-phenylpiperazine b dicarboxylic acid chlorides (non-aqueous phase) dicarboxylic acid chloride terephthaloyl chloride isophthaloyl chloride 3,3'-dibenzoyl chloride 4,4'-dibenzoyl chloride pypidine-2,5־dicarbonyl chloride pyridine-3,5-dicarbonyl chloride nyridine-2,4-dicarbonyl chloride pyridine-2,6-dicarbonyl chloride pyrazine-2,5־dicarbonyl chloride

2,6-dimethyl-3,5-pyridinedicarbonyl chloride fumaric acid chloride group 2. polyoxamides

-ג diamines (aqueous phase)' vide group 1. b oxalyl chloride (non-aqueous phase ) group 3. polyurea a diamines (aqueous phase) vide group 1.

b phosgene (non-aqueous phase) c dicarbamyl chloride (non-aqueous phase)

A dicarbamyl chloride can be prepared from a secondary diatribe and an excess of phosgene )N-H+C1-CO-C1—i)N-CO-Cl

From piperazine and phosgene:

Cl-CO-N^ / N-CO-C1

From 1,*t-bis(methylamino)-benzene and phosgene

C1-CO-N(CH )-'0&lt;M(CH )-CO-C1

From 1,4־-bi 3( phenylamine )benzene and phosgene

Cl-C0-N(CzH_c)-'0i-N(C_rH )-CO-C1

5 0 ׳_'5 0 d diisocynates (non-aqueous phase)

A diisocyanate can be prepared from a diamine and phosgene

-HC1

-R-11H +C1-C0-C1—) -R-NH-C0-C1 —)-R-N=C=O diisocyanate

2.4- toluenediisocyanate

2.5- toluenediisocyanate

2.6- toluenediisocyanate . .

p-phenylenediisocyanate m-phenylenediisocyanate

4,4'-bisphenylenediisocyanate

3,3'-dimethyl-4,4'-bisphenylenediisocyanate

3,3' -dimetho'xy-4,4 ^,-bisphenylenediisocyanate group 4 polybisureas a diisocyanates (non-aqueous phase) vide group 3 b hydrazine (aqueous phase) group 5. polyurethanes a diamines (aqueous phase) vide group 1 b dichloroformates (non-aqueous phase) dichloroformate

1,4-phenylenebischloroformate c diisocyanates (non-aqueous phase) vide group 3 d dioles (aqueous phase) diol hydroquinone resorcinol catechol methylhydroquinone

4-methylcatechol

2- methylresorcinol

3- methoxycatechol

2.4- dihydroxyacetophenone

2.5- dihydroxyacetophenone

0,0'-biphenol

4,4'-dihydroxybiphenyl

2.3- dihydroxypyridine

2.6- dihydroxypyridine

4.6- dihydroxypyridine group 6. polyesters a diols (aqueous phase) vide group 5 b dicarboxylic add chlorides (non-aqueous phase) vide group 1 group 7. polyesters a diols (aqueous phase) vide group 5 b oxalyl chloride (non-aqueous phase) group 8. polycarbonates ־^{: :} a diols (aqueous phase) vide group 3 b dichloroformates (non-aqueous phase) vide group 5 _c phosgene (non-aqueous phase) group 9. polymonoacylhydrazines a dihydrazines (aqueous phase) dihydrazine bi shydrazine (N,N¹-diaminopiperazine)

N,N'-diamino-trans-2,5-dimethylpiperazine

1.3- phenylenedihydrazine

1.4- phenylenedihydrazine b dicarboxylic acid chlorides (non-aqueous pnase) vide group 1 group 10. polydiacylhydrazine a dihydrazides (aqueous phase)

A dihydrazide can be prepared according to

2H₂N-NH₂ + CH -O-CO-P.-CO-O-CH^—ל Η₂Ν-ΝΗ-00-λ-00-ΝΗ-1'Έ₂

־1743783/2

A dihydrazide isophthalic acid dihydrazide terephthalic acid dihydraside

2.5- pyridinedicarboxylic acid dihydrazide

2.6- pyridinedicarboxylic acid dihydrazide pyrazine-2,5-dicarboxylic acid dihydrazide b dicarboxylie chlorides (non-aqueous phase) vide group 1 c hydrazine (aqueous phase) group 11. polybisdiacy!hydrazines a dicarboxylic chlorides (non-aqueous phase) vide group 1 b oxalic acid dihydrazides (aqueous phase) group 12. polysemicarbazides a diisocyanates (non-aqueous phase) vide group 3 b dihydrazines (aqueous phase) vide group 9 group 13. polyacylsemicarbazides a dihydrazides (aqueous phase) vide group 10 b (non-aqueous phase) vide group 3 group 14. polybisacylsemicarbazides a diisocyanates (non-aqueous phase) vide group 3 b oxalic acid dihydrazides (aqueous phase) group 15. pdyurethana acylsemicarbazidea a diisocyanates (non-aqueous phase) vide group 3 b hydroxyacylhydrazines (aqueous phase)

Dimensions of the foils

The dimensions of the foils depend on the concentration of reactants A and B, and on the degree of dispersion.

A condition is that the foil should be a solid, one dimension being at least 10 times smaller than the dimensions perpendicular to it. This should be noted with regard to what follows.

The dimensions in the plane of the foils may exceed 1 m if coarse dispersed particles are present but this should be avoided as much as possible. Under certain circumstances dimensions may also become smaller than 8.1 urn, for instance because of tearing as a result of excessive stirring. This shoddiaiso be avoided. Suitable dimensions are in the range of 1 p and 1 mm.

43783/2 3

Regarding the thickness of the foils the dispersion procedure must be such that little or no foils axe formed with a thickness above 10 1m. Suitable thicknesses axe 1 ym or smaller.

Generally the process must be carried out in such a way that at least 70% of the foils lie within the above-mentioned range.

General Example

In Table A the experiments are tabulated carried out via stages a and 8 according to the methods described in section 2. Column b of Table £ specifies to which group (see tables of section 3.1 for the division in groups) the polymer foxmed belongs. It is also indicated whether a linear (L) or a crosslinked (H) polymer has been formed. In column c the working procedure followed in stages a and 8 is specified, as it has been specified in the procedure scheme of Figure 1, for example 1,1 means that methods I and 1 were used. Upon application of method I the non-aqueous phase (column f), in which reactant B (column e) has been dissolved, is dispersed in 1500 cc water. In experiment 18 the non-aqueous phase was dispersed in 500 cc water only. To the dispersion obtained 500 cc of an aqueous solution of reactant A (column d) which may contain an acid acceptor (column מ) or a buffer (column n), is then added.

The dispersion of the non-aqueous phase in the aqueous phase was obtained by stirring with the aid of a Temp-Fluid TF 25 stirring machine manufactured by Oskar Krieger at Muttinz in Switzerland. The speed of the stirrer used to obtain the dispersion is listed in column 1 in revolutions per minute (rpm).

After tho interfacial polycondensation reaction in stage a was completed the sire of the particles of the product formed was determined (see column k).

All reactions were carried out at ambient temperature.

Polymer foils were formed during all experiments specified in Table A.

Bxample I

With the polymer foils,_vgorme!d during experiments nos. 3 and 6 (see Table A), dynamic membranes had been formed in a reverse osmosis apparatus. For both experiments as substrate a Millipore filter type GSWP was used with an average pore else of 0.22 um.

4־

Thia type of filter has been manufactured from blended cellulose-esters. The membraneB formed were tested at a S 2 system pressure of 50.10 N/m, a NaCl concentration &lt;tff 1.5 kg/p and a temperature af 20-25°C (N here designates ΝβνίΛη^Β), The formation of foils was carried out as follows: a Utilisation test with polymer foils of experiment no.3 After evaporation of the car bentetrachloride from the mother liquor the polymer formed was filtered off and washed with demineralized water and ethyl alcohol. Then the polymer was dispersed in an alcoholic soap solution (0.1 M NaOH and 2 g. Teepol/1) and applied in the reverse osmosis apparatus^ After five hours of dynamic membrane forming, the apparatus was rinsed clean for one hour with demineralized water, whereupon NaCl was added to the supply, whereupon the following properties were determined: Salt-retention : 32t

Flux s 4.9.10 m³/m²s.

Teepol is a Trade Mark for a surfactant with as active compounds 60-70 parts by weight of alkylbenzenesulphonate and 40-30 parts by weight of polyethylene oxide. These compounds are dissolved in water.

b Utilization test with polymer foils of experiment bo.6 After evaporation of the hexane, NaOH was added to the solution to increase the pH to 10 to 11, whereupon the solution was brought to 100.C. Next the polymer was filtered off and washed with demineralized water. After redispersing in demineralized water the polymer was applied in the reverse osmosis apparatus and NaCl was added. After 2 hours the pH of the apparatus liquid was increased to pH 10 with the aid of NaOH. After 22 hours the following membrane properties were measured:

Salt-retention ? 38%

Flux : 6.8.10“⁵ m³/n²s^

The foils indicated by na3 and no.6 were circular. Bo. 3 consisted. for more than 90% of foils with a diameter of 5 to 6 pm and a thickness of 0.2 to 0.3 ym. In experiment no.6 these dimensions were about 150 ym and 0.9 pm.

Τ Λ B L 3 A

<td> a</td><td> b</td><td> c *</td><td> d</td><td></td><td> e</td><td></td><td> f K</td><td></td>

<td> test</td><td> group*</td><td colspan="2"> inetbod aqueous phase</td><td> ג</td><td> non-aqu3cus phase</td><td></td><td> non-/⁷ volume</td><td></td>

<td> no,</td><td colspan="2"> (section !ection 3) 2</td><td> reactant A</td><td> vvIlL.« mol/l—</td><td> reactant B</td><td> cone, taol/1</td><td> aqueous aqueous phase phase ml</td><td></td>

<td> 1</td><td> μ</td><td> 1,4</td><td> piperazine</td><td> 0.05</td><td> terephthaloylchloride</td><td> 0.1</td><td> hexane 2000</td><td></td>

<td> 2</td><td> 1,1</td><td> • 1,4</td><td> diaminoanisol</td><td> 0.05</td><td> terephthaloylchloride</td><td> 0.1</td><td> hexane 2000 ׳ carbon-</td><td></td>

<td>¹ 3</td><td rowspan="2"> 1,1</td><td> 1,2</td><td> diamino-ethane</td><td> Q.2</td><td> isophthaloylchloride</td><td> 0.2</td><td> tetra -2000</td><td></td>

<td> _k</td><td></td><td></td><td></td><td></td><td></td><td> chloride</td><td> k.,</td>

<td> 1 4</td><td> . M</td><td> 1,4</td><td> 3,3' diaminoberizidine</td><td> 0.025</td><td> terephthaloylchloride</td><td> 0.2</td><td> benzene 2000</td><td></td>

<td> ־ ל</td><td> 1,N</td><td> 1,4</td><td> 3,3¹ diaminobensidine</td><td> 0.025</td><td> terephthaloylchloride</td><td> 0.2</td><td> hexane 2000</td><td></td>

<td> 6</td><td> 1,»</td><td> 1,4</td><td> 3,3' dianiinobenzidins</td><td> 0.05</td><td> terephthaloylchlorida₁</td><td> 0.1</td><td> hexane 2000</td><td></td>

<td> 1</td><td> 2,1</td><td> 1,4</td><td> 2,6 diaminopyridine</td><td> 0.05</td><td> oxalylchloride</td><td> 0.2</td><td> hexane 2000</td><td></td>

<td> 8</td><td> 2,1</td><td> 11,4</td><td> 2,6 diaminopyridine</td><td> 0.05</td><td> oxalylchloride</td><td> 0,2</td><td> hexane 2000</td><td> GJ si</td>

<td> 9</td><td> 3,1</td><td> '10</td><td> 1,4 diaminobeMne .</td><td> 0.05</td><td> toluenediisocyanate</td><td> 0.2</td><td> hexane 2000</td><td> CO W</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> hi</td>

<td> 10 </td><td> 3,1</td><td> 1,4</td><td> piperazine</td><td> 0,05</td><td> toluenediisocyanate</td><td> 0.2</td><td> hexane 2000</td><td></td>

<td> 11</td><td> 3,1</td><td> 11,4</td><td> 2,6 diaminopyridine</td><td> 0,05</td><td> toluenedi isocyanate</td><td> 0.2,</td><td> hexane 2000</td><td></td>

<td> 12</td><td> 4,1</td><td> 1,1</td><td> hydrazine</td><td> 0.05</td><td> tola?nediisocy:1nate</td><td> 0,2</td><td> hexane</td><td></td>

<td></td><td> TABLE A</td><td> cont.</td>

<td> a b</td><td> c d</td><td> e f g</td>

<td> , , + test group</td><td> method aqueous phase </td><td> u non-a(|0ous phase non- volume</td>

<td> no. (section 3)</td><td> section reactant A 2</td><td> cone. reactant B cone, aqueous aqueous mol/1 11101/1 phase phase ml</td>

<td> B</td><td> 5,1</td><td> Π,4</td><td> hydroquinone 0,05</td><td> toluenediisocyanate</td><td> 0.2</td><td> hexane</td><td> 2000</td>

<td> 14 1</td><td> 5,1</td><td> 11,4</td><td> resorcinol 0,05</td><td> toluenediisocyanate</td><td> 0.2</td><td> hexane </td><td> 2000</td>

<td> S 15 </td><td> 5,N</td><td> 11,4</td><td> pyrogallol 0.0$</td><td> toluenediisocyanate</td><td> 0.2</td><td> hexane</td><td> 2000</td>

<td> 1 16</td><td> 6,N</td><td> 1,4</td><td> D-glucose 0,025</td><td> terephthaloylchlorido</td><td> 0.2</td><td> benzene carbon-</td><td> 2000</td>

<td> 1?</td><td> 6,«</td><td> 11,4</td><td> pyrogallol O'.OJ</td><td> adipoylchloride</td><td> 0.2</td><td> tetrachloride</td><td> 2000</td>

<td> 18</td><td> 10,1</td><td> 1,4</td><td> hydrazine 0.05</td><td> ter^phthaloylchloride</td><td> 0.2</td><td> benzene</td><td> 1000</td>

<td> 19</td><td> 11,1</td><td> 1,4</td><td> oxalic acid dihydrazide 0.05</td><td> tarephthaloylchlorida</td><td> 0.1</td><td> hexane</td><td> 2000</td>

<td> 20</td><td> 11,1</td><td> . 1,4</td><td> oxalic acid dihydrazide 0*05</td><td> terephthaloylchloride</td><td> 0.1</td><td> pentane</td><td> 2000</td>

<td> 21</td><td> 4,1י</td><td> 1,4</td><td> oxalic acid dihyteide 0,05</td><td> toluenediisocyanate</td><td> 0.2</td><td> hexane</td><td> 2000</td>

+ L = linear polymer.

N = crosslinked pGlyrar

TAB 1,3 A - 2^nd cor.t.

<td> a</td><td> h</td><td> i</td><td> j</td><td colspan="2"> k 1</td><td> m</td><td> n</td><td> 0</td>

<td> test</td><td> volume</td><td> pH</td><td> react-</td><td> particles</td><td> rpm</td><td> acid</td><td> buffer</td><td> liemarks</td>

<td> no,</td><td> non</td><td> aqueous</td><td> ion</td><td> size</td><td colspan="2"> stirr--ccjptor</td><td> con.</td><td></td>

<td></td><td colspan="2">₄aqueous 'phase</td><td> time</td><td> before</td><td> ing</td><td> conc.iriol/1</td><td> mol/1</td><td></td>

<td></td><td> phase</td><td> at start</td><td> min,</td><td> evapor-</td><td> device</td><td></td><td></td><td></td>

<td></td><td> ’ ml</td><td></td><td></td><td> ation</td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td> yum</td><td></td><td></td><td></td><td></td>

<td> 1 1 M</td><td> 100</td><td> 11.7</td><td> 10</td><td> 23-140</td><td> 2200</td><td> 0,1ל tiajCOj</td><td></td><td></td>

<td> 2 I</td><td> 100</td><td> '4.6</td><td> 10</td><td> 14-60</td><td> 2200</td><td></td><td> 0,2 acetic acid/</td><td></td>

<td> 1</td><td></td><td></td><td></td><td></td><td></td><td></td><td colspan="2"> /0,2 sodium acetate</td>

<td> 3</td><td> 50</td><td> 11.?</td><td> b</td><td> -</td><td> 4000</td><td> 0,1 JajCO}</td><td></td><td></td>

<td> 4</td><td> 100</td><td> 2</td><td> '10</td><td> 14-140</td><td> 2200</td><td></td><td></td><td> pH with HC1 to 2</td>

<td> • 5</td><td> 100</td><td> 2</td><td> 10</td><td> 14-140 ‘</td><td> 2200</td><td></td><td></td><td> pH with HC1 to 2</td>

<td> 6</td><td> 100</td><td> 2.2</td><td> 1</td><td> 50-350</td><td> 1800</td><td></td><td></td><td> pH with HC1 to 2,2</td>

<td> 1</td><td> 100</td><td> 11.7</td><td> 10</td><td> 30-150</td><td> ?200</td><td> 0,15 lfa_?C0₃</td><td></td><td> small yield of polymer</td>

<td> 8</td><td> 100</td><td> 8.4</td><td> 10</td><td> 30-90</td><td> 1800</td><td> 0.06 JUHCO^</td><td></td><td> reaction pH 6</td>

A ω X) CO u to

<td> T A B L E A - 3^’ cont, 1</td>

<td> a h ' i j k 1 m 0 ט י</td>

<td> 1 A׳‘ ץ ' \ test volume pH react- particle rpm acid buffer Remarks</td>

<td> no, non aqueous ion size stirr- acceptor con.</td>

<td> aqueous phase time before ing cono.mcl/1 mol/1 . ׳</td>

<td> phase at start min, evapor- device</td>

<td> ation</td>

<td> r_____________________</td>

<td> 1 9 100 4.6 10 14-300 2200 0.2 acetic acid/</td>

<td>_w ’ /0,2 soiijin awtats.</td>

<td> .k ., .,</td>

<td> I 10 100 11.7' 10 '50-100 2200 0,15fe₂00j</td>

<td> 11 100 . 8.5 10 . ¢0-150 1800 0,06 feHCOj Mera .evaporation</td>

<td> already a membranous</td>

<td> product</td>

<td> 12 100 11.7 10 ]0-70 2200 0,15</td>

<td> 13 100 8 10 10-100 1800 0.06 MC0-J</td>

<td> 14 100 7.7 10 140.06 1800 ׳ 90־ WO, * . ג w</td>

<td> 15 100 7.6 10 80-90 1800 O.O6HaHC0j ”</td>

<td> 16 100 11,6 10 28-140 2200 0,075 l'^a2^c01</td>

<td> 17 ICC 7.8 10 — 1800 0,06 21:100!</td>

<td rowspan="2"> a</td><td rowspan="2"> h</td><td rowspan="2"> i</td><td colspan="5"> T A B L j A - 4^^j1 cont,</td><td rowspan="2"> 0</td>

<td> j</td><td> k</td><td> 1</td><td> m</td><td> n</td>

<td> test . no,</td><td> volume non aqueous phase</td><td> pH aqueous phase at start</td><td> reaction time , in in,</td><td> particle size ' before mpor- at ion ; pm</td><td colspan="2"> rpm acid stirr- acceptor ing conc.,mol/l device</td><td> buffer con. 1aol/l</td><td> / Remarks</td>

<td> 1 n 18 VI</td><td> 500</td><td> ii.,7</td><td> 10</td><td> 40-1¢</td><td> 2200</td><td> 0.15 lia₂C0^</td><td></td><td></td>

<td> ' 19</td><td> 100</td><td> 11.7</td><td> 10</td><td> 50-350</td><td> 2200</td><td> 0.15 Na₂C0₃</td><td></td><td></td>

<td> 20</td><td> 100</td><td> y</td><td> 10</td><td> סן</td><td> 2200</td><td></td><td> 0,01 borax + some dr.yHCL</td><td></td>

<td> .21</td><td> 100</td><td> 11.7</td><td> 10</td><td> ?0-80</td><td> 2200</td><td> 0,15 Na^COj</td><td></td><td></td>

w sJ CO w

N