FR2511614A1 - PROCESS FOR THE PRODUCTION OF A CATION EXCHANGE RESIN - Google Patents

Abstract

THE PROCESS ACCORDING TO THE INVENTION CONSISTS OF POLYMERIZING IN SUSPENSION A MIXTURE OF MONOMERS CONSISTING OF: 1STYRENE; 2DU DIVINYLBENZENE; AND 3 AT LEAST ONE COMPOUND CHOSEN FROM ACRYLIC ACID, METHACRYLIC ACID AND THEIR LOWER ALKYL ESTERS, AND TO SULPHONATE THE RESULTING COPOLYMER PARTICLES.

Description

The present invention relates to a prior method

  gies for the production of an internal cation exchange resin

  uplifting from an industrial point of view.

  In general, a cation exchange resin is produced by sulfonation of styrene-divinylbenzene copolymer particles. As a cation exchange resin having a high ion exchange capacity per unit weight is preferred, the sulfonation should be performed consistently

  in all polymer particles from the surface inward

  However, the styrene-divinyl copolymer particles

  benzene have the disadvantage that the interior of the particles is

not easily sulfonated.

  To increase the ion exchange capacity, a method is known which consists in swelling the polymer particles with a swelling agent consisting of an organic solvent such as

  nitrobenzene, and then to sulfonate the particles thus treated.

  The following problems are encountered in this process, however.

  The first problem is that due to the use of a blowing agent, the number of processing steps increases and further, due to the presence of a blowing agent in the residual acid after sulfonation, the waste acid can not be recycled for reuse, which has an economic disadvantage In order to overcome this drawback, there is known

  process using a copolymer containing acrylonitrile

  trileen in addition to styrene and divinylbenzene, and the sulfonation is carried out substantially in the absence of a blowing agent, as described, for example, in Japanese patent publications 10343/1963 and 12602/1966 This method is preferred because sulfonation takes place easily without the use of a blowing agent, but it has the drawback that it causes a large number of cracks on the copolymer particles. A process has not yet been found in which sulfonation takes place

  easily, even in the absence of a blowing agent.

  The second problem is that the cation exchange resin obtained by sulfonation is colored brown and that part of the coloring components in the resin is dissolved in

  the solution to be treated while using the Ce resin

  leads is particularly increased when the resin is used after storage for a long time. It is believed that the reason is that a portion of the coloring components formed in the sulfonation stage transforms during storage of the resin into a component soluble in l water We have not yet proposed a

  method for effectively solving the second problem.

  Due to the above, the Applicant has found, following various researches to obtain a method making it possible to overcome the two disadvantages described above,

  that these problems can be solved by using a copo-

  lymer comprising styrene, divinylbenzene and a certain

specified compound.

  The object of the invention is therefore to propose a pro-

  yielded for the production of a cation exchange resin which consists in polymerizing in suspension a mixture of monomers comprising (1) styrene, (2) divinylbenzene and (3) at least one compound chosen from acrylic acid, acid methacrylic

  and their lower alkyl esters.

  The copolymer particles which are the matrix

  of the cation exchange resin according to the invention are

  killed from a copolymer obtained by suspension polymerization of a

  mixture of monomers comprising (1) styrene, (2) divinyl-

  benzene and (3) acrylic acid, methacrylic acid or

  a lower alkyl ester of acrylic or methacrylic acid.

  The lower alkyl esters according to the invention

  contain 1 to 6 carbon atoms in the alkyl residue.

  Suitable examples of component (3) are methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, etc. The amount of component (3) used is from 2 to mole%, preferably from 4 to 10 mole% relative to austyrene. If the amount is too small, the sulfonation of the resulting copolymer particles is not easily carried out and, on the contrary, if the quantity is too high; ion exchange groups are not introduced due to a decrease in the amount of styrene. The amount of divinylbenzene used depends on the

  desired degree of crosslinking of the copolymer and is generally

  ment from 0.8 to 55 mol%, preferably from 1.5 to 45 mol%, per

compared to styrene.

  It is new in the production of a cation exchange resin to use a copolymer containing acrylic acid, methacrylic acid or one of their lower alkyl esters as particles of copolymer It is known to use in the production of an anion exchange resin a copolymer

  containing methyl methacrylate, tri- trimethacrylate

  methylolpropane, acrylonitrile, isoddcyl methacrylate, etc. as copolymer particles, as described for example in

  U.S. Patent 4,207,398.

  However, cation exchange resins and anion exchange resins are different by the production processes, processing conditions, etc. and they have

  also different properties For example, in the pro-

  duction of an anion exchange resin, acrylonitrile is used as similar to methyl methacrylate, as described in US Patent 4,207,398 In contrast to the production of a cation exchange resin, l the use of acrylonitrile is not preferred, as appears from the data described below This difference is due to the technical difference between the anion exchange resins and the resins

cation exchangers.

  According to the invention, the monomers (1) to (3) are polymerized in suspension. Water is generally used as a dispersing medium. The amount of water used is from 1 to 10 times.

the total weight of the monomers.

  Poly-alcohol is used as a dispersing agent.

  vinyl, carboxymethylcellulose, etc. The amount of the dispersing agent is generally 0.1 to 5.0% 7 by weight, relative to the

total weight of the monomers.

  The polymerization initiators which can be used are conventional substances such as

  benzoyl, or nitrogen-type catalysts and the amount of ini-

  titrator is from 0.01 to 15% by weight relative to the total weight of the monomers. The polymerization is generally carried out at a temperature of approximately 50 to 900 ° C. for approximately 3 to 30 hours, for example according to the following procedures: predetermined quantities of water and of dispersing agent are placed in a

  polymerization reactor, then the mono-

  mothers in which a polymerization initiator has been dissolved and the oil-in-water suspension is subjected to polymerization

  resulting at a predetermined temperature with nitrogen bubbling.

  The copolymer particles obtained by the poly-

  suspended merization are crack-free beads having a particle diameter of about 0.1 to 1.0 min. The particles are then sulfonated to give the desired cation exchange resin. Sulfonation is usually carried out by stirring the copolymer particles in sulfuric acid

  95-100% The amount of sulfuric acid used is general-

  ment from 3 to 30 times the weight of the copolymer used.

  The invention encompasses a process in which the sulfona-

  tion is carried out substantially in the absence of a blowing agent and also a process in which the sulfonation is carried out in the presence of a blowing agent In the case where the blowing agent is not used, the residual acid obtained after sulfonation has the advantage of not containing organic solvent and in the case where the swelling agent is used, the content of coloring components in the resulting cation exchange resin is advantageously

weaker.

  The sulfonation temperature is usually at 1500 C, preferably 90-110 ° C when no blowing agent is used and 50-100 C, preferably 60-90 C when using a blowing agent When the temperature is too high in the case where the blowing agent is used, it is not possible to satisfactorily lower the content of the coloring component of the resin The time required for the

  sulfonation is usually 3 to 30 hours.

  The blowing agent used is an organic solvent, for example an aromatic hydrocarbon such as nitrobenzene, toluene or xylene, a halogenated aromatic hydrocarbon such as chlorobenzene or dichlorobenzene, a halogenated aliphatic hydrocarbon, such as carbon tetrachloride or dichloride ethylene; etc.

  Coating particles swelling treatment

  The polymer is generally carried out by suspending the particles.

  copolymer cules in an organic solvent before sulfonation,

  then stirring at 50-100 C for 1 to 5 hours.

  The copolymer particles are filtered after the sulfonation reaction and washed in a conventional manner and then they are recovered after transformation, if desired, into the H form.

in the Na form.

  As described above, the production of the resin

  cation exchanger using consisted copolymer particles

  as essentially in the components specified according to the invention can bring the following advantages: (1) Even when the sulfonation is carried out without

  blowing agent, the resulting resin is not cracked, sulfona-

  tion takes place easily in a uniform manner and the resulting residual acid does not contain an organic solvent; and (2) when the sulfonation is carried out using a blowing agent, the content of components in the resulting resin

dyes decreases.

  The process according to the invention therefore makes it possible to produce

  advantageously a cation exchange resin which is of interest

industrially healthy.

  The following examples and comparative examples illustrate

  the invention without however limiting its scope.

  EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLES 1 AND 2 A 3-liter flask fitted with a stirrer, a thermostat and a nitrogen inlet pipe is loaded with 2000 g of water and 3.0 g polyvinyl alcohol A mixture of 550 g of styrene, 80 g of divinylbenzene, a compound indicated in Table I below and 0.5 g of benzoyl peroxide is then added to the flask. The polymerization is carried out at 80 ° C. 8 hours in

stirring with bubbling nitrogen.

  The copolymer particles are recovered from the polymerization mixture. 100 g of copolymer particles are suspended in 650 g of 100% sulfuric acid and sulfonated at

 C for 5 hours.

  The ion exchange capacity of the cation exchange resins is measured and the proportion of particles cracked during sulfonation: the results obtained are

  indicated in Table I below.

TABLE I

  Example n Compound Quantity Capacity Proportion

added * 1 share exchange

of ions * 2 cules fis-

  surées * 3 (moles) m eq / (7) 1 ethyl acrylate 6 4.5 5 2 ethyl acrylate 15 4.5 5 3 methyl methacrylate 6 4.5 5 4 ethyl methacrylate 5 4.5 5 4 methacrylic acid 7 4.5 10

Example

comparative

1 2.0 80

  2 acrylonitrile 6 4.5 80 Remarks * 1): compared to styrene * 2): for 1 g of the resin * 3): particles with cracks, in 100 particles of resin

  * 4): the amount of benzoyl peroxide is 1.0 g.

Examples 6 to 9

  We load a 3 liter flask fitted with an agitator, a thermostat or a nitrogen intake manifold with 2000 g

11614

  water and 3.0 g of polyvinyl alcohol A mixture of 550 g of styrene and 80 g of divinylbenzene, a third monomer as indicated in Table II below and 0.5 g of peroxide is added to the flask. benzoyl The mixture is polymerized at 800 ° C. for 8 hours while stirring with bubbling nitrogen. The copolymer particles are recovered from the mixture after polymerization. 100 g of the particles are stirred in a mixture of 50 g of a swelling agent indicated in table II and 200 ml.

  of water at 80 ° C. for 1 hour The particles of copo-

  lymer and then sulfone them in 500 ml sulfuric acid

at 1007 to 80 ° C for 15 hours.

  The particles of sulfonated copolymer are filtered and

  they are washed 10 times with 500 ml of water.

  The measurement of the ion exchange capacity and the elution test of the coloring components of the resulting cation exchange resins are carried out: the results obtained are

indicated in Table II.

  Comparative Example 3 The same procedure is repeated as in Example 6, except that the polymerization is carried out without adding the third

  monomer The result obtained is shown in Table II.

  Comparative Examples 4 and 5 The same procedure is repeated as in Example 6, except that the polymer particles are not treated with a swelling agent and the sulfonation is carried out at the temperature indicated in Table II. The results obtained are indicated

in Table II below.

  It is understood that the invention is not limited

  to the preferred embodiments described above by way of illustration.

  that those skilled in the art can make various modifications thereto.

  various changes without departing from the framework and

the spirit of the invention.

TABLE II

Example N

  Third monomer Quantity * Compound * added methacrylic acid methacrylic acid methyl methacrylate ethyl methacrylate 2.5 6.0 2.5 2 X 5 Blowing agent used Nitrobenzene II It Capacity Exchange ion sulfonation temperature (C) (meq / g)

4.52

4.42

4> 53

4 X 52

Example com-

parative 3 "i 4

"5

  methacrylic acid methacrylic acid * Quantity used: compared to styrene ** Elution test: after storage in air for 3 months, 50 g of resin are immersed in 200 ml of water

  at 60 ° C. for 3 hours and the degree of coloring of the water is measured.

r Lj VI o - Ielution test **

(APIIA)

0 O *. 2.5 2.5 4.25 4.30 4.53

Claims (8)

  1 Process for the production of an exchange resin   cations, characterized in that it consists of polymerizing in addition   board a mixture of monomers comprising (1) styrene, (2) divinylbenzene and (3) at least one compound chosen from acrylic acid, methacrylic acid and their lower alkyl esters,   and sulfonating the resulting copolymer particles.   2 Method according to claim 1 characterized in that the amount of the component (3) used is from 2 to 20 mol%, compared to styrene.   3 Method according to claim 1 characterized in that the amount of divinylbenzene is 0.8 to 55 mol%, per compared to styrene.   4 Method according to claim 1 characterized in that the copolymer particles have a particle diameter of 0.1 to 1.0 mm.   Process according to Claim 1, characterized in that the sulfonation is carried out using sulfuric acid at 95-100%.   6 Process for the production of a cation exchange resin, characterized in that it consists in polymerizing in suspension   a mixture of monomers comprising (1) styrene, (2) divinyl-   benzene and (3) at least one compound chosen from acrylic acid, methacrylic acid and their lower alkyl esters, and to sulfonate the resulting copolymer particles practically   in the absence of a blowing agent consisting of an organic solvent.   7 Method according to claim 6, characterized in that   that the sulfonation temperature is 50 to 150 C.   8 Process for the production of a cation exchange resin, characterized in that it consists in polymerizing in suspension   a mixture of monomers comprising (1) styrene, (2) divinyl-   benzene and (3) at least one compound chosen from acrylic acid, methacrylic acid and their lower alkyl esters, and to sulfonate the resulting copolymer particles practically in the presence of a swelling agent consisting of an organic solvent, at 50-100 C.   9 Method according to claim 8 characterized in that the swelling agent is at least one organic solvent chosen from aromatic hydrocarbons, aromatic hydrocarbons   halogenated and halogenated aliphatic hydrocarbons.