U.S. patent application number 10/299299 was filed with the patent office on 2003-06-19 for monodisperse anion exchangers.
Invention is credited to Halle, Olaf, Klipper, Reinhold, Podszun, Wolfgang, Schmid, Claudia, Seidel, Rudiger, Soest, Hans-Karl.
Application Number | 20030114544 10/299299 |
Document ID | / |
Family ID | 7709547 |
Filed Date | 2003-06-19 |
United States Patent
Application |
20030114544 |
Kind Code |
A1 |
Klipper, Reinhold ; et
al. |
June 19, 2003 |
Monodisperse anion exchangers
Abstract
Process for preparing monodisperse weakly basic or optionally
strongly basic anion exchangers of the poly(meth)acrylamide type,
the ion exchangers themselves and their use.
Inventors: |
Klipper, Reinhold; (Koln,
DE) ; Halle, Olaf; (Koln, DE) ; Schmid,
Claudia; (Leichlingen, DE) ; Podszun, Wolfgang;
(Koln, DE) ; Seidel, Rudiger; (Leverkusen, DE)
; Soest, Hans-Karl; (Koln, DE) |
Correspondence
Address: |
WILLIAM GERSTENZANG
NORRIS, MCLAUGHLIN & MARCUS, P.A.
220 EAST 42ND STREET, 30TH FLOOR
NEW YORK
NY
10017
US
|
Family ID: |
7709547 |
Appl. No.: |
10/299299 |
Filed: |
November 19, 2002 |
Current U.S.
Class: |
521/32 |
Current CPC
Class: |
B01J 39/18 20130101;
C08F 20/56 20130101; B01J 41/07 20170101; B01J 39/04 20130101; B01J
39/04 20130101; B01J 41/07 20170101; B01J 41/05 20170101; B01J
41/05 20170101; B01J 41/14 20130101; B01J 39/04 20130101; B01J
39/18 20130101; B01J 41/14 20130101 |
Class at
Publication: |
521/32 |
International
Class: |
C08J 005/20; C08F
002/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2001 |
DE |
10161979.0 |
Claims
We claim
1. Process for producing monodisperse weakly basic anion exchangers
of the poly(meth)acrylamide type, wherein a) in a first stage a
monomer mixture of one or more different acrylic compounds and one
or more different crosslinkers or one or more different monovinyl
aromatic compounds and one or more different crosslinkers are
injected or sprayed into a liquid essentially immiscible with the
monomer mixture to form droplets, the droplets are then
encapsulated and polymerized, and the encapsulated and polymerized
droplets are then reacted with a feed of acrylic compounds and
crosslinkers in a seed-feed process and the resulting product is
polymerized to form monodisperse crosslinked acrylic polymer beads
or monodisperse crosslinked acryl-containing polymer beads, and b)
the product obtained by step a) is then introduced into a liquid
amine of the diamine type to form a suspension, the suspension is
heated to temperatures above 100.degree. C., optionally distilled,
stirred for several hours, and the resulting aminated bead polymer
is washed amine-free.
2. Process for producing monodisperse weakly basic anion exchangers
of the poly(meth)acrylamide type according to claim 1 wherein a) in
a first stage a monomer mixture of one or more different acrylic
compounds and one or more different crosslinkers is injected or
sprayed into a liquid essentially immiscible with the monomer
mixture to form droplets, the droplets are then encapsulated and
polymerized, and the encapsulated and the polymerized droplets are
then reacted according to step b).
3. Process according to claim 1, wherein the monodisperse
crosslinked acrylic polymer beads or monodisperse crosslinked
acryl-containing polymer beads in process step a) are produced by a
combination of spraying (jetting), encapsulation and
polymerization.
4. Process according to claim 1 or 2, wherein said polymerization
of said encapsulated droplets is a partial polymerization or a
complete polymerization.
5. Process according to claims 1 or 2, wherein the droplets are
microencapsulated with a complex coacervate.
6. Process according to claim 5, wherein the droplets are
microenclapsulated in the presence of a protecting colloid.
7. Process according to claims 1 or 2, wherein the polymerization
of the encapsulated droplets is carried out in the presence of at
least one initiator.
8. Process according to claims 1 or 2, wherein the monomer mixture
further comprises porogens and the droplets, after polymerization,
form macroporous crosslinked bead polymers.
9. Process according to claims 1 or 2, wherein said liquid
essentially immiscible with the monomer mixture is water.
10. Process according to claim 6, wherein said protecting colloid
is selected from the group consisting of gelatin, starch,
polyvinylalcohol, polyvinylpyrrolidone, polyacrylic acid,
polymethacrylic acid copolymers of (meth)acrylic acid and
copolymers of (meth)acrylic esters.
11. Process according to claims 1 or 2, wherein said crosslinkers
are selected from the group consisting of divinylbenzene,
divinyltoluene, trivinylbenzene, divinylnaphthalene,
trivinylnaphthalene, 1,7-octadiene, 1,5-hexadiene, ethylene glycol
dimethacrylate, trimethylolpropane trimethacrylate, allyl
methacrylate and diethylene glycol divinyl ether.
12. Process according to claim 7, wherein the initiator is a peroxy
compound or an azo compound.
13. Process according to claim 12, wherein said peroxy compound is
a member of the group consisting of dibenzoyl peroxide, dilauroyl
peroxide, bis(p-chlorobenzoyl) peroxide, dicyclohexyl
peroxydicarbonate, tert-butyl peroctoate, tert-butyl
peroxy-2-ethylhexanoate, 2,5-bis(2-ethyl-hexanoylp-
eroxy)-2,5-dimethylhexane and tert-amylperoxy-2-ethylhexane, and
said azo compound is a member of the group consisting of
2,2'-azobis(isobutyronitr- ile) and
2,2'-azobis(2-methylisobutyronitrile).
14. Process according to claims 1 or 2, wherein said liquid amine
of the diamine type is selected from the group consisting of
1-amino-3-dimethylaminopropane, diethylenetriamine and
triethylenetetramine.
15. Process for preparing strongly basic monodisperse anion
exchangers of the poly(meth)acrylamide type containing quaternary
amino groups, which comprises reacting the aminated bead polymer of
claims 1 or 2, process step b) with alkylhalides or
arylhalides.
16. Process of claim 15, wherein said alkylhalides or arylhalides
are selected from the group consisting of chloromethane, benzyl
chloride or mixtures of chloromethane and benzyl chloride
17. Weakly basic monodisperse anion exchangers of the
poly(meth)acrylamide type obtained by a) injecting or spraying a
monomer mixture of one or more different acrylic compounds and one
or more different crosslinkers or one or more monovinyl aromatic
compounds and one or more crosslinkers into a liquid which is
essentially immiscible with the monomer mixture, to form droplets,
encapsulating and polymerizing said droplets and then reacting them
with a feed of acrylic compounds and crosslinkers according to a
seed-feed process to produce monodisperse crosslinked acrylic
polymer beads or monodisperse crosslinked acryl-containing polymer
beads, and b) the product obtained by step a) is then introduced
into a liquid amine of the diamine type, heating the suspension to
temperatures above 100.degree. C. and stirring for a several hours,
and washing the aminated bead polymer until it is amine-free.
18. Weakly basic monodisperse anion exchangers of the
poly(meth)acrylamide type obtained by a) injecting or spraying a
monomer mixture of one or more different acrylic compounds and one
or more different crosslinkers into a liquid which is essentially
immiscible with the monomer mixture, to form droplets,
encapsulating and polymerizing said droplets and then b)
introducing the product obtained by step a) into a liquid amine of
the diamine type, heating the suspension to temperatures above
100.degree. C. and stirring for a several hours, and washing the
aminated bead polymer until it is amine-free.
19. Process according to claim 1, wherein in process step a) the
monovinyl aromatic compound is styrene and the crosslinker is
divinylbenzene.
20. Strongly basic monodisperse anion exchangers of the
poly(meth)acrylamide type obtained by reacting the aminated bead
polymer from process step b) of either claim 1 or claim 2 partially
or completely with alkyl halides or aryl halides to give strongly
basic monodisperse anion exchangers of the poly(meth)acrylate type
containing quaternary amino groups.
21. Process for removing anions, color particles or organic
components from aqueous or organic solutions and condensates, which
comprises contacting said aqueous or organic solutions and
condensates with the monodisperse weakly basic or strongly basic
anion exchangers of claims 17, 18 or 20.
22. Method of purifying and treating water of the chemical industry
and the electronic industry which comprises contacting said water
with the monodisperse strongly basic or weakly basic anion
exchangers of claims 17,18 or 20.
23. Method of demineralizing aqueous solutions and/or condensates
which comprises contacting said aqueous solutions and/or
condensates with the monodisperse strongly basic or weakly basic
anion exchangers of claims 17,18 or 20 in combination with gel-type
and/or macroporous cation exchangers.
24. Combinations of monodisperse strongly basic or weakly basic
anion exchangers of the poly(meth)acrylamide type according to
claims 17,18 or 20 together with gel-type and/or macroporous cation
exchangers.
25. The process of claim 1, 2, 17 or 18 wherein said temperature is
160.degree. C. to 200.degree. C.
Description
[0001] The present invention relates to a process for preparing
monodisperse weakly basic, and optionally monodisperse strongly
basic, anion exchangers of the poly(meth)acrylamide type, and to
uses thereof.
[0002] Monodisperse anion exchangers of the poly(meth)acrylamide
type according to the present invention are anion exchangers
starting from either monovinyl aromatic compounds or acrylic
compounds which are copolymerized with further acrylic compounds,
and then reacted with amines of the diamine-type and functionalized
with alkylhalides or arylhalides.
BACKGROUND OF THE INVENTION
[0003] From the prior art, heterodisperse anion exchangers of the
poly(meth)acrylamide type are already known. These are a class of
anion exchangers which can be used in practice for numerous
different applications.
[0004] An important area of use of heterodisperse anion exchangers
of the poly(meth)acrylamide type is water treatment technology, in
which it is possible to remove anions, for example, chloride,
sulphate or nitrate, and weak acids such as salicylic acid and
carbonic acid; organic acids such as formic acid, acetic acid,
citric acid, humic acids and others.
[0005] Currently, both gel-type and macroporous heterodisperse
anion exchangers of the poly(meth)acrylamide type are used in
decolorizing press juices from beets and sugar cane. In the course
of the complex production process of sugar extraction, the press
juices from the beets, preferably sugar beets, and the sugar cane
discolor. Pigments, for example melanoidines and caramel colors are
formed. U.S. Pat. No. 4,082,701 discloses the use heterodisperse
anion exchangers of the poly(meth)acrylamide type, for decolorizing
pigment solutions. Raw solutions of liquid sugar syrup or invert
sugar syrup are also currently desalted using heterodisperse anion
exchangers of the poly(meth)acrylamide type.
[0006] It is also known to use gel-type or macroporous
heterodisperse anion exchangers of the poly(meth)acrylamide type
for the removal of acids or acidic components from whey and fruit
thin press juices.
[0007] A known process for preparing heterodisperse anion
exchangers of the poly(meth)acrylamide type is aminolysis of
crosslinked acrylic ester bead polymers with polyamines according
to U.S. Pat. No. 2,675,359, CZ-A 169 356, DD 99 587 or U.S. Pat.
No. 5,414,020.
[0008] The crosslinked (meth)acrylic ester resin bead polymers used
for the aminolysis are prepared in the prior art as gel-type or
macroporous resins. They are prepared in mixed polymerization by
the suspension polymerization process. This produces heterodisperse
bead polymers having a broad particle size distribution in the
range from approximately 0.2 mm to approximately 1.2 mm.
[0009] The heterodisperse anion exchangers of the
poly(meth)acrylamide type obtained after the subsequent aminolysis
can be quaternized by alkylating agents. The reaction to be
performed here to give strongly basic groups can be carried out in
the range from 1 to 100%, that is to say completely. Customary
alkylating agents are alkyl halides or aryl halides or mixtures of
the two, for example chloromethane according to U.S. Pat. No.
4,082,701 or benzyl chloride.
[0010] In U.S. Pat. No. 2,675,359, gel-type and macroporous
heterodisperse bead polymers based on a
methylacrylate-divinylbenzene copolymer are reacted with
diethylenetriamine.
[0011] DD 99 587 describes the preparation of solid-grain weakly
basic heterodisperse anion exchangers based on polyacrylic esters.
The grain solidity is achieved by means of the fact that, after the
copolymer is reacted with the polyamine, the resin is treated with
a water-miscible solvent which swells the resin to a lesser extent
than water.
[0012] Suitable solvents used are, for example, methanol, ethanol,
acetone or mixtures thereof. 99% of the beads are obtained without
cracks or fissures.
[0013] Without the treatment with methanol, for example, 35% of the
beads have cracks and fissures.
[0014] The heterodisperse anion exchangers of the
poly(meth)acrylamide type, depending on the charged form of the
resin, that is to say depending on the type of counter ion to the
nitrogen, exhibit differing resin volumes. When converted from the
chloride form to the free base form, the resin swells markedly.
Conversely, it shrinks on conversion from the free base form to the
chloride form. In the industrial use of these heterodisperse anion
exchangers of the poly(meth)acrylamide type, therefore, charging
and regeneration is associated in each case with shrinkage or
swelling, respectively. In the course of long-term use, however,
these heterodisperse anion exchangers are regenerated several
hundred times. The shrinking and swelling operations occurring in
the course of this stress the bead stability so greatly that a
fraction of the beads develop cracks, finally even fracturing.
Fragments are produced which lead to blockages in the service
apparatus and the columns, and impede flow, which in turn leads to
an increased pressure drop. In addition, the fragments contaminate
the medium being treated, preferably water, and thus reduce the
quality of the medium or the water.
[0015] The flow of water through a column packed with beads,
however, is impeded not only by resin fragments, but also by fine
polymer beads, if present. An increase in pressure drop occurs. Due
to the particle size distribution of known heterodisperse anion
exchangers of the poly(meth)acrylamide type, beads of differing
diameters are present. The presence of such fine beads additionally
increases the pressure drop.
[0016] Seidl et al., Chemicky prumysl, roc. 29/54 (1979) cis 9,
470, studied the aminolysis reaction of crosslinked acrylic ester
resins and found that, in addition to the acrylamide unit, free
acrylic acid units are also formed. All acrylamide resins exhibit
free acrylic acid units.
[0017] After completion of charging of heterodisperse anion
exchangers of the poly(meth)acrylamide type with anions, therefore,
the resin is regenerated with dilute sodium hydroxide solution in
order to prepare it for new charging. Sodium hydroxide solution
residues are washed out of the resin with water. In addition the
carboxylate ion which results from treating the carboxylic acid
group with sodium hydroxide solution is hydrolysed by the water
washing. During production of the resins a low conductivity of the
effluent water (wash water) from the resin is desired, since
otherwise impure water is present. The goal is to achieve low
conductivity using small amounts of wash water, since this can be
regarded as a sign that only small amounts of weakly acidic groups
remain.
SUMMARY OF THE INVENTION
[0018] Starting from the prior art, an object of the present
invention was to provide not only weakly basic, but also strongly
basic, monodisperse anion exchangers of the poly(meth)acrylamide
type with high mechanical and osmotic stability of the beads, low
pressure drop of the bead bed in use and low wash water consumption
and high purity of the monodisperse anion exchanger itself.
[0019] In accordance with the present invention, this object,
therefore is achieved by a process for preparing monodisperse anion
exchangers of the poly(meth)acrylamide type, wherein
[0020] a) in a first stage a monomer mixture of
[0021] one or more different acrylic compounds and one or more
different crosslinkers or one or more different monovinyl aromatic
compounds and one or more different crosslinkers
[0022] are injected or sprayed into a liquid essentially immiscible
with the monomer mixture to form droplets, the droplets are then
encapsulated and polymerized, and the encapsulated and polymerized
droplets are then reacted with a feed of acrylic compounds and
crosslinkers in a seed-feed process and the resulting product is
polymerized to form monodisperse crosslinked acrylic polymer beads
or monodisperse crosslinked acryl-containing polymer beads, and
[0023] b) in a second stage the monodisperse crosslinked acrylic
polymer beads or acryl-containing polymer beads (when starting from
monovinyl aromatic compounds) obtained from the first stage are
introduced into a liquid amine of the diamine type to form a
suspension, the suspension is heated to temperatures above
100.degree. C., optionally distilled, stirred for several hours,
and the resulting aminated bead polymer is washed amine-free.
[0024] In case that the monomer mixture of step a) contains acrylic
compounds, a feed of the same acrylic compounds is preferred.
[0025] Alternatively the process can be started from one or more
different acrylic compounds and one or more different crosslinkers
without using a feed in step a) and the droplets formed are then
encapsulated and polymerized and the polymerized droplets are then
reacted according to step b). In this case the object of the
present invention is achieved by a process for preparing
monodisperse anion exchangers of the poly(meth)acrylamide type,
wherein
[0026] a) in a first stage a monomer mixture of one or more
different acrylic compounds and one or more different crosslinkers
is injected into a liquid essentially immiscible with the monomer
mixture to form droplets, the droplets are then encapsulated and
polymerized,
[0027] b) and the product obtained by step a) is introduced into a
liquid amine of the diamine type to form a suspension, the
suspension is heated to temperatures of from 160.degree. C. to
210.degree. C., optionally distilled, stirred for several hours,
and then the resulting aminated bead polymer is washed
amine-free.
[0028] Optionally, to prepare strongly basic monodisperse anion
exchangers of the poly(meth)acrylamide type, there follows a third
stage, in which:
[0029] c) the aminated bead polymer prepared according to the
second stage is partially or completely reacted with alkylhalides
or arylhalides to give the corresponding strongly basic
monodisperse anion exchangers of the poly(meth)acrylamide type
having quaternary amino groups.
[0030] In process step a), the polymerization of the encapsulated
droplets may be a partial polymerization or a complete
polymerization. Those partial or complete polymerizations are
described in U.S. Pat. No. 5,068,255 and U.S. Pat. No. 5,834,524,
both are hereby incorporated by reference into the present
application.
[0031] Preferably, methanol is distilled off in the second
stage.
[0032] The crosslinkers used in the practice of the invention
include, for example, polyvinylalkyl compounds, polyvinylaromatic
compounds, diene compounds and mixtures thereof.
DETAILED DESCRIPTION
[0033] Surprisingly, in the inventive process, complex and
expensive treatment of the monodisperse bead polymer with methanol,
for example, after the amination, can be dispensed with, and weakly
basic or, optionally, strongly basic monodisperse anion exchangers
of the poly(meth)acrylamide type are obtained having outstanding
osmotic and mechanical stability, low conductivities of the resin
effluent water, decreased pressure drop in use and markedly
decreased wash water consumption.
[0034] The term "monodisperse" as used herein means substances for
which at least 90% by volume or by mass of the particles have a
diameter which is distributed in the range around the most frequent
diameter having a width of .+-.10% of the most frequent diameter
(i.e., the "mode").
[0035] For example, for a substance having the most frequent
diameter of 0.5 mm (i.e., a distribution with a mode of 0.5 mm), at
least 90% by volume or 90% by mass are within a size range between
0.45 mm and 0.55 mm, in the case of a substance having the most
frequent diameter of 0.7 mm, at least 90% by volume or 90% by mass
are in a size range between 0.63 mm and 0.77 mm.
[0036] In principle, in process step a), two different methods can
be used. A distinction is made here between direct injection and
the seed-feed process.
[0037] When direct injection is used in process step a), a monomer
mixture comprising one or more different acrylic compounds,
preferably (meth)acrylate esters, particularly preferably methyl
acrylate or (meth)acrylonitrile, and one or more crosslinkers, for
example divinylbenzene or diethylene glycol divinyl ether are
injected into a liquid which is essentially immiscible with the
monomer mixture resulting in monodisperse droplets, then
encapsulated and then the resultant monomer droplets are
polymerized.
[0038] When the seed-feed process is used in process a), again two
variants are possible.
[0039] Either the process starts from a monovinyl aromatic compound
such as styrene and divinylbenzene as a crosslinker and a
monodisperse styrene-divinylbenzene bead polymer is obtained:
[0040] In such case for example a monomer mixture of
[0041] a) 98.5-99.98% by weight of styrene;
[0042] b) 0.01-2% by weight of divinylbenzene; and
[0043] c) 0.01-0.05% by weight of ethylstyrene;
[0044] injected into a liquid essentially immiscible with the
monomer mixture to form droplets, the droplets are then
encapsulated and polymerized and the encapsulated and polymerized
droplets are then fed with the above-described feed of acrylic
compounds and one or more crosslinkers. Monodisperse crosslinked
acryl-containing polymer beads are obtained. Other possible
monovinyl aromatic compounds are ethylstyrene or substituted
styrenes and the substituents can be C.sub.1-C.sub.4 alkyl or
halogen, preferred chlorine.
[0045] Or, the bead polymer obtained in accordance with the
above-described direct injection process is taken and fed with a
feed of acrylic compounds and one or more crosslinkers to give the
desired bead polymer with subsequent polymerization.
[0046] In all cases it is advisable to keep the monodisperse
bead-type crosslinked acrylic polymers as water-free as possible so
that these can be used in the subsequent process step b).
[0047] The monomer mixture to be used in the first stage a)
comprises 1 to 50% by weight, preferably 1 to 25% by weight,
particularly preferably 1.5 to 12% by weight, especially preferably
2 to 8% by weight, crosslinker and 50 to 99% by weight, preferably
75 to 99% by weight, particularly preferably 88 to 98.5% by weight,
and especially preferably 92 to 98% by weight, acrylic compounds,
preferably (meth)acrylic esters or (meth)acrylonitrile.
Particularly preferred starting materials are diethyl glycol
divinyl ether as crosslinker and methyl acrylate.
[0048] The beads prepared according to the seed-feed process are
significantly larger than the fine seed beads obtained by the
direct spraying process.
[0049] Techniques for preparing monodisperse crosslinked bead
polymers by the seed-feed process or by the direct spraying process
(jetting) are described, for example, in U.S. Pat. No. 4,444,961,
U.S. Pat. No. 4,427,794, U.S. Pat. No. 4,419,245, U.S. Pat. No.
5,231,115 or U.S. Pat. No. 4,564,644, the entire contents of which
are hereby incorporated by reference into the present
application.
[0050] In U.S. Pat. No. 4,427,794, the monodisperse crosslinked
vinylaromatic bead polymer is prepared in the desired size by
injecting (spraying) the monomer mixture into a liquid which is
essentially immiscible with the monomer mixture, then encapsulating
it and polymerizing the resultant monomer droplets. This method is
even used in the present invention.
[0051] Preferred (meth)acrylic esters of (meth)acrylonitriles in
the context of the present invention are monoethylenically
unsaturated compounds, for example alkyl acrylates or alkyl
methacrylates, particularly preferably methyl (meth)acrylate, ethyl
(meth)acrylate or acrylonitrile.
[0052] A (meth)acrylic ester which is particularly preferred in the
context of the present invention is methyl acrylate.
[0053] Preferred crosslinkers which are used in the context of the
present invention in process step a) are multifunctional
ethylenically unsaturated compounds such as divinylbenzene,
divinyltoluene, trivinylbenzene, divinylnaphthalene,
trivinylnaphtalene, 1,7-octadiene, 1,5-hexadiene, diethylene glycol
divinyl ether, ethylene glycol dimethacrylate, trimethylpropane
trimethacrylate or allyl methacrylate.
[0054] The particular type of crosslinker to be used is selected in
accordance with the expected use of the polymer beads.
Divinylbenzene, for example, is suitable in many cases. For most
applications, commercial divinylbenzene quality grades which also
comprise ethylvinylbenzene, in addition to the divinylbenzene
isomers, are sufficient.
[0055] In the event that the starting material is prepared from
styrene-divinylbenzene bead polymers by the seed-feed process, the
monodisperse bead-type crosslinked acrylic polymer to be used in
the inventive process in step b) still contains 0.001 to 8% by
weight, preferably 0.0015 to 5% by weight, divinylbenzene.
[0056] In a preferred embodiment of the inventive process,
microencapsulated acrylic polymers or microencapsulated
acryl-containing polymers are used in process step b).
[0057] For the preparation of microencapsulated acrylic polymers or
microencapsulated acryl-containing polymers for process step b),
the materials known for use as complex coacervates are suitable, in
particular polyesters, natural or synthetic polyamides,
polyurethanes, polyureas.
[0058] As a natural polyamide, gelatin, for example, is
particularly highly suitable. This is used, in particular, as
coacervate or complex coacervate. Gelatin-containing complex
coacervates in the context of the invention are taken to mean,
especially, combinations of gelatin with synthetic
polyelectrolytes. Suitable synthetic polyelectrolytes are
copolymers having incorporated units of, for example, maleic acid,
acrylic acid, methacrylic acid, acrylamide or methacrylamide.
Particularly preferably, acrylic acid or acrylamide is used.
Gelatin-containing capsules can be cured using conventional curing
agents, for example formaldehyde or glutardialdehyde. The
encapsulation of monomer droplets with gelatin, gelatin-containing
coacervates and gelatin-containing complex coacervates is described
in detail in U.S. Pat. No. 4,427,794. The methods of encapsulation
with synthetic polymers are known. A highly suitable method is, for
example, phase boundary condensation, in which a reactive component
(for example an isocyanate or an acid chloride) which is dissolved
in the monomer droplet is brought to reaction with a second
reactive component (for example an amine) which is dissolved in the
aqueous phase.
[0059] The optionally microencapsulated monomer droplets may
comprise an initiator or mixtures of initiators to initiate the
polymerization. Initiators which are suitable for the inventive
process are, for example, peroxy compounds, such as dibenzoyl
peroxide, dilauroyl peroxide, bis(p-chlorobenzoyl) peroxide,
dicyclohexyl peroxydicarbonate, tert-butyl peroctoate, tert-butyl
peroxy-2-ethylhexanoate, 2,5-bis(2-ethylhexanoylpe-
roxy)-2,5-dimethylhexane or tert-amylperoxy-2-ethylhexane, and azo
compounds, such as 2,2'-azobis(isobutyronitrile) or
2,2'-azobis(2-methylisobutyronitrile).
[0060] The initiators are generally used in amounts of 0.05 to 2.5%
by weight, preferably 0.1 to 1.5% by weight, based on the monomer
mixture.
[0061] Further additives which can be used in the optionally
microencapsulated monomer droplets are optionally porogens in order
to generate a macroporous structure in the bead polymer. Suitable
compounds for this are organic solvents which dissolve poorly, or
swell, the resultant polymer. Examples which may be mentioned are
hexane, octane, isooctane, isododecane, methyl ethyl ketone,
butanol or octanol or isomers thereof.
[0062] Substances which are suitable porogens are also, especially,
organic substances which dissolve in the monomer, but dissolve the
polymer poorly, or swell it (precipitant for polymers), for example
aliphatic hydrocarbons, as described in German Patent 1 045 102 or
German Patent 1 113 570.
[0063] The porogen used can, for example, be alcohols having 4 to
10 carbon atoms, such as those described in In U.S. Pat. No.
4,382,124 for producing monodisperse macroporous
styrene/divinylbenzene-based bead polymers. This patent also
provides a survey of the preparation methods for macroporous bead
polymers and is hereby incorporated by reference into the present
application.
[0064] The proportion of porogen used for the synthesis of
monodisperse macroporous anion exchangers based on
poly(meth)acrylamide is 1 to 50% by weight, preferably 3 to 30% by
weight, particularly preferably 4 to 20% by weight, based on the
monomer.
[0065] The terms microporous or gel-type or macroporous have been
described in detail in the specialist literature, for example in
Seidl, Malinsky, Dusek, Heitz, adv. Polymer Sci., Vol. 5 pages 113
to 213 (1967).
[0066] Preferred bead polymers in the context of the present
invention have a monodisperse gel-type structure.
[0067] The optionally microencapsulated monomer droplet can, if
appropriate, also comprise up to 30% by weight (based on the
monomer) of crosslinked or uncrosslinked polymer. Preferred
polymers are derived from the said monomers, particularly
preferably from styrene.
[0068] The mean particle size of the optionally encapsulated
monomer droplets is 10-1000 .mu.m, preferably 100-1000 .mu.m. The
inventive process is also very suitable for the preparation of
monodisperse bead-type polymers.
[0069] In process step a), the preferably aqueous phase may
optionally comprise a dissolved polymerization inhibitor. Suitable
inhibitors in the context of the present invention are both
inorganic and organic substances. Examples of inorganic inhibitors
are nitrogen compounds, such as hydroxylamine, hydrazine, sodium
nitrite and potassium nitrite, salts of phosphorous acid, such as
sodium hydrogen phosphite and sulphur compounds, such as sodium
dithionate, sodium thiosulphate, sodium sulphite, sodium
bisulphite, sodium rhodanide or ammonium rhodanide. Examples of
organic inhibitors are phenolic compounds, such as hydroquinone,
hydroquinone monomethyl ether, resorcinol, catechol,
tert-butylcatechol, pyrogallol or condensation products of phenols
with aldehydes. Other suitable organic inhibitors are nitrogen
compounds. These include hydroxylamine derivatives, for example
N,N-diethylhydroxylamine, N-isopropylhydroxylamine and sulphonated
or carboxylated N-alkylhydroxylamine derivatives or
N,N-dialkylhydroxylamine derivatives, hydrazine derivatives, for
example N,N-hydrazinodiacetic acid, nitroso compounds, for example
N-nitrosophenylhydroxylamine, N-nitrosophenylhydroxylamine ammonium
salt or N-nitrosophenylhydroxylamin- e aluminium salt. The
concentration of the inhibitor is 5 to 1000 ppm (based on the
aqueous phase), preferably 10 to 500 ppm, particularly preferably
10 to 250 ppm.
[0070] The optionally microencapsulated monomer droplets are
polymerized in process step a), as mentioned above, optionally in
the presence of one or more protecting colloids in the aqueous
phase to give the monodisperse acrylic polymer beads. Suitable
protecting colloids are natural or synthetic water-soluble
polymers, for example gelatin, starch, polyvinyl alcohol, polyvinyl
pyrrolidone, polyacrylic acid, polymethacrylic acid, or copolymers
of (meth)acrylic acid and (meth)acrylic esters. Very highly
suitable protecting colloids are also cellulose derivatives, in
particular cellulose esters and cellulose ethers, such as
carboxymethyl cellulose, methyl hydroxyethyl cellulose, methyl
hydroxypropyl cellulose and hydroxyethyl cellulose. Gelatin is
particularly highly suitable. The amount of protecting colloid used
is generally 0.05 to 1% by weight, based on the aqueous phase,
preferably 0.05 to 0.5% by weight.
[0071] The polymerization to give the monodisperse crosslinked
acrylic polymer beads as starting material for process step b) can
optionally also be carried out in the presence of a buffer system.
Preference is given to buffer systems which set the pH of the
aqueous phase at the start of polymerization to between 14 and 6,
preferably between 13 and 8. Under these conditions protecting
colloids containing carboxylic acid groups are present wholly or
partly as salts. In this manner the action of the protecting
colloids is favorably influenced. Particularly highly suitable
buffer systems comprise phosphate salts or borate salts. The terms
phosphate and borate in the context of the invention also include
the condensation products of ortho forms of corresponding acids and
salts. The concentration of phosphate or borate in the aqueous
phase is 0.5 to 500 mmol/l, preferably 2.5 to 100 mmol/l.
[0072] The stirrer speed in the polymerization to form the
monodisperse crosslinked acrylic polymer is less critical and, in
contrast to the conventional bead polymerization, has no effect on
the particle size. Low stirrer speeds are employed which are
sufficient to keep the suspended monomer droplets in suspension and
to support the removal of the heat of polymerization. For this
task, various stirrer types can be used. Particularly suitable
types are gate stirrers having an axial action.
[0073] The volumetric ratio of encapsulated monomer droplets to
aqueous phase is 1:0.75 to 1:20, preferably 1:1 to 1:6.
[0074] The polymerization temperature depends on the decomposition
temperature of the initiator used, and is generally between 50 and
180.degree. C., preferably between 55 and 130.degree. C. The
polymerization takes from about 1/2 hour to several hours. It has
proven useful to employ a temperature program in which the
polymerization is started at low temperature, for example
60.degree. C., and the reaction temperature is increased with
advancing degree of polymerization. In this manner, the demand for
a safe reaction course and a high degree of polymerization may be
fulfilled very well, for example. After polymerization the polymer
is isolated by conventional methods, for example by filtration or
decanting, and, if appropriate, washed.
[0075] The monodisperse acrylic polymer to be used for the
amination in process step b) can be prepared as described above in
a plurality of individual steps. Seed polymer based on
styrene-divinylbenzene, prepared according to U.S. Pat. No.
4,427,794, is fed, for example with a mixture of methyl acrylate,
diethylene glycol divinyl ether and dibenzoyl peroxide,
polymerized, washed and dried (Preparation of copolymer I).
[0076] The dried copolymer I is fed with further monomer mixture
methyl acrylate, diethylene glycol divinyl ether and dibenzoyl
peroxide, polymerized, washed and dried (Preparation of copolymer
II).
[0077] Copolymer II is then, according to the invention, aminated
in process step b) and optionally quaternized in a process step
c).
[0078] In process step b), the monodisperse crosslinked acrylic
polymer from process step a) is reacted with amines, preferably in
the absence of water. In this case, the amines are not only
reactant, but also constitute the stirring medium. However, if
appropriate, the stirring medium used for aminolysis can instead be
inert liquids such as alkanes, for example alkanes which are liquid
in the range from 120.degree. to 250.degree. C.
[0079] Amines of the diamine-type are those having at least two
amino groups.
[0080] Suitable amines in the context of the present invention are
compounds with at least two amino groups in the molecule such as,
for example, 1-amino-3-dimethylaminopropane, triethylenetetramine,
diethylenetriamine, tetraethylenepentamine,
penta-ethylenehexamine.
[0081] The amines are used in excess, based on the groups to be
aminolysed; preferably in amounts of 1.1-8 mol, in particular 2 to
6 mol, of amine per mole of ester or nitrile groups.
[0082] According to the inventive process, the temperature of the
suspension in process step b) is raised to above 100.degree. C.,
preferably 120.degree. C. to 210.degree. C., particularly
preferably 160.degree. C. to 210.degree. C., in particular
preferably 170.degree. C. to 200.degree. C.
[0083] The suspension in process step b) is stirred according to
the invention for a plurality of hours, preferably 10 to 30 hours,
particularly preferably 16 to 25 hours.
[0084] The aminated bead polymer produced according to the
inventive process in process step b) is washed amine-free,
preferably until the amine content is less than 0.01% by
weight.
[0085] The aminated bead polymer obtainable by the inventive
process is optionally, in an additional process step, partially or
completely alkylated to give strongly basic monodisperse anion
exchangers containing quaternary groups of the poly(methacryl)amide
type.
[0086] Partially or completely in the context of the present
invention means that, in the amination, approximately 10-98% of the
basic groups, preferably 35-98% of the basic groups are present as
quaternary amino groups.
[0087] The alkylating agent used in the context of the present
invention for process step c) is preferably chloromethane or benzyl
chloride or a mixture of chloromethane and benzyl chloride.
[0088] The alkylating agents are generally used in amounts of 10 to
100 mol %, based on the amount of weakly basic groups, these being
added to an aqueous suspension of the aminated bead polymer from
process step b).
[0089] The present invention, however, also relates to the weakly
basic monodisperse anion exchangers of the poly(meth)acrylamide
type themselves obtainable by a process comprising the following
steps:
[0090] a) injecting or spraying a monomer mixture of one or more
different acrylic compounds and one or more different crosslinkers
or one or more monovinyl aromatic compounds and one or more
crosslinkers into a liquid which is essentially immiscible with the
monomer mixture, to form droplets, encapsulating and polymerizing
said droplets and then reacting them with a feed of acrylic
compounds and crosslinkers according to a seed-feed process to
produce monodisperse crosslinked acrylic polymer beads or
monodisperse crosslinked acryl-containing polymer beads, and
[0091] b) introducing the product obtained by step a) into a liquid
amine of the diamine type, heating the suspension to temperatures
above 100.degree. C. and stirring for a several hours, and washing
the aminated bead polymer until it is amine-free.
[0092] In case that the monomer mixture of step a) contains acrylic
compounds, a feed of the same acrylic compounds is preferred.
[0093] Alternatively when the process is started from one or more
different acrylic compounds and one or more different crosslinkers
without using a feed in step a) the present invention however, also
relates to the weakly basic monodisperse anion exchangers of the
poly(meth)arylamide type themselves obtainable by a process
comprising the following steps:
[0094] a) injecting or spraying a monomer mixture of one or more
different acrylic compounds and one or more different crosslinkers
into a liquid which is essentially immiscible with the monomer
mixture, to form droplets, encapsulating and polymerizing said
droplets and
[0095] b) introducing the product obtained by step a) into a liquid
amine of the diamine type, heating the suspension to temperatures
above 100.degree. C. and stirring for a several hours, and washing
the aminated bead polymer until it is amine-free.
[0096] The present invention, however, also relates to the strongly
basic monodisperse anion exchangers of the poly(meth)acrylamide
type obtainable by partially or completely reacting the aminated
bead polymer obtained from process step b) with alkyl halides or
aryl halides to give strongly basic monodisperse anion exchangers
containing quaternary amino groups of the poly(meth)acrylamide
type.
[0097] On account of the particular osmotic and mechanical
stability and the high purity not only of the weakly basic but also
of the strongly basic monodisperse anion exchangers of the
poly(meth)acrylamide type, these are suitable for numerous
applications.
[0098] The present invention therefore also relates to the use of
the inventive monodisperse weakly basic or strongly basic anion
exchangers of the poly(meth)acrylamide type
[0099] for removing anions from aqueous or organic solutions or
their vapors,
[0100] for removing anions from condensates,
[0101] for removing color particles from aqueous or organic
solutions,
[0102] for decolorizing and desalting glucose solutions, wheys,
weak gelatin solutions, fruit juices, fruit wines or sugars,
preferably mono- or disaccharides, in particular fructose
solutions, cane sugar, beet sugar solution, for example in the
sugar industry, in dairies, in the starch industry and in the
pharmaceutical industry,
[0103] for removing organic components from aqueous solutions, for
example humic acids from surface water.
[0104] In addition, the inventive weakly basic or strongly basic
anion exchangers of the poly(meth)acrylamide type can be used for
purifying and treating waters in the chemical industry and
electronics industry, in particular for producing ultrapure
water.
[0105] In addition, the inventive weakly basic or strongly basic
monodisperse anion exchangers of the poly(meth)acrylamide type can
be used in combination with gel-type and/or macroporous cation
exchangers for demineralizing aqueous solutions and/or condensates,
in particular in the sugar industry.
[0106] The present invention therefore also relates to
[0107] processes for removing anions, preferably anions of strong
acids, such as chloride, sulphate, nitrate, from aqueous or organic
solutions and their vapors,
[0108] processes for removing anions, preferably anions of strong
acids, such as chloride, sulphate, nitrate, from condensates,
[0109] processes for removing color particles from aqueous or
organic solutions,
[0110] processes for decolorizing and demineralizing glucose
solutions, wheys, weak gelatin solutions, fruit juices, fruit wines
or sugars, preferably mono- or disaccharides, in particular cane
sugar, fructose solutions or beet sugar solutions, for example in
the sugar industry, starch industry or pharmaceutical industry, or
in dairies,
[0111] processes for removing organic components from aqueous
solutions, for example humic acids from surface water
[0112] using the inventive weakly basic or strongly basic
monodisperse anion exchangers of the poly(meth)acrylamide type.
[0113] The inventive monodisperse weakly basic or strongly basic
monodisperse anion exchangers of the poly(meth)acrylamide type can,
furthermore, be used finely ground in powder form as strongly basic
anion exchangers alone or in mixtures with cation exchangers for
filtering and demineralizing waters, for example condensates. Their
advantages are the high reaction rate and the excellent filtration
efficiency for suspended particles.
EXAMPLE 1
Preparation of a Copolymer I
[0114] An aqueous solution of 3.6 g of boric acid and 1.0 g of
sodium hydroxide in 1218 g of deionized water is placed in a 4 l
glass reactor. To this are added 264.7 g of monodisperse
microencapsulated seed polymer containing 99.63% by weight of
styrene, 0.3% by weight of divinylbenzene and 0.07% by weight of
ethylstyrene. The divinylbenzene used was a conventional
commercially-available isomer mixture of 80.6% by weight of
divinylbenzene and 19.4% by weight of ethylstyrene. The seed
polymer was prepared in accordance with U.S. Pat. No. 4,427,794 and
the seed polymer capsule wall consisted of a formaldehyde-cured
complex coacervate of gelatin and an acrylamide/acrylic acid
copolymer. The mean particle size of the seed polymer was 220 .mu.m
and the .O slashed.(90)/.O slashed.(10) value was 1.05. The mixture
is stirred at a stirrer speed of 220 rpm. In the course of 30
minutes, a mixture of 605.1 g of methyl acrylate, 30.2 g of
diethylene glycol divinyl ether and 3.39 g of dibenzoyl peroxide
(75% strength by weight) is added. The polymerization mixture is
stirred for 2 hours at room temperature, the gas space being purged
with nitrogen. Thereafter a solution of 2.7 g of methyl
hydroxyethyl cellulose in 132.3 g of deionized water is added. The
batch is heated to 63.degree. C. in the course of 75 minutes and
kept at this temperature for 5 hours. The batch is then heated to
95.degree. C. in the course of 60 minutes and stirred for a further
120 minutes at this temperature. The batch, after cooling, is
washed with deionized water over a 40 .mu.m screen and is then
dried at 80.degree. C. for 18 hours in a drying cabinet. 833 g of a
bead-type copolymer I having a mean particle size of 330 .mu.m and
a .O slashed.(90)/.O slashed.(10) value of 1.21 are obtained, which
means 96 Vol % are in a size range between 297 .mu.m and 363
.mu.m.
Preparation of a Copolymer II as Starting Material for the
Inventive Process
[0115] An aqueous solution of 1.08 g of boric acid and 0.34 g of
sodium hydroxide in 917 g of deionized water is placed in a 4 l
glass reactor. To this are added 288.7 g of copolymer I from
Example 1 a). The mixture is stirred at a stirrer speed of 220 rpm.
In the course of 30 minutes a mixture of 439.6 g of methyl
acrylate, 21.9 g of diethylene glycol divinyl ether and 2.46 g of
dibenzoyl peroxide (75% strength by weight) is added. The mixture
is stirred at room temperature for 2 hours, the gas space being
purged with nitrogen. Thereafter a solution of 1.83 g of methyl
hydroxyethyl cellulose in 89.8 g of deionized water is added. The
batch is heated to 60.degree. C. in the course of 75 minutes and
kept at this temperature for 5 hours. The batch is then heated to
95.degree. C. in the course of 60 minutes and stirred at this
temperature for a further 120 minutes. The batch, after cooling, is
washed with deionized water over a 40 .mu.m screen and then dried
for 18 hours at 80.degree. C. in a drying cabinet. 667 g of a
bead-type copolymer II having a mean particle size of 450 .mu.m and
a .O slashed.(90)/.O slashed.(10) value of 1.25 are obtained, which
means 95 Vol % are in a size range between 405 .mu.m and 495
.mu.m.
Reaction of the Monodisperse Crosslinked Methyl Acrylate Copolymer
I with 1-amino-3-dimethylaminopropane
[0116] 280 grams of the bead polymer from 1 a) are placed in a 3
liter stirred autoclave at room temperature. 1600 ml of
1-amino-3-dimethylamino- propane are added at room temperature. The
suspension is heated to 185.degree. C. in the course of 2.5 hours
and stirred for a further 24 hours at this temperature. After
cooling to room temperature, the reaction mixture is flushed from
the autoclave into a column with isopropanol and eluted with 4
further bed volumes of isopropanol. The resin is then eluted with 8
bed volumes of deionized water.
[0117] Yield: 1570 ml
[0118] Elemental composition:
[0119] 63.4% by weight of carbon
[0120] 10.0% by weight of hydrogen
[0121] 15.75% by weight of nitrogen
[0122] 11.45% by weight of oxygen.
[0123] Resin stability
[0124] Original state: 99% perfect beads
[0125] After the roller test: 96% perfect beads
[0126] After the swelling stability test: 98% perfect beads
[0127] Useable capacity of the resin: 0.94 mol/l
[0128] Wash water to 10 .mu.S/cm: 7.9 bed volumes
[0129] Wash water to 2 .mu.S/cm: 15.9 bed volumes
[0130] HCl number of the resin: 1.736 mol/l
[0131] NaOH number of the resin: 0.032 mol/l
[0132] Process description for preparing strongly basic
monodisperse anion exchanger of the poly(meth)acrylamide type.
[0133] Reaction (partial quaternization) of the monodisperse
crosslinked dimethylaminopropylamide group-containing bead polymer
I from the inventive process with chloromethane.
[0134] 800 ml of weakly basic resin washed amine-free are
introduced into 880 ml of deionized water. The suspension is heated
to 40.degree. C. In the course of 1 hour 28.05 grams of
chloromethane are added. The mixture is then stirred for a further
6 hours at 40.degree. C.
[0135] After cooling the resin is filtered off, washed with
deionized water and its volume is determined.
[0136] Yield: 940 ml
[0137] Resin stability
[0138] Original state: 98% perfect beads
[0139] After the roller test: 96% perfect beads
[0140] After the swelling stability test: 98% perfect beads
[0141] Useable capacity of the resin: 0.94 mol/l
[0142] Wash water to 10 .mu.S/cm: 4.8 bed volumes
[0143] Wash water to 2 .mu.S/cm: 24.2 bed volumes
[0144] HCl number of the resin: 0.74 mol/l
[0145] NaCl number of the resin: 0.49 mol/l
[0146] NaNO.sub.3 number of resin: 0.49 mol/l
[0147] From this is calculated a degree of quaternization of
39.8%.
[0148] Analytical Methods:
[0149] Particle Size
[0150] Conventional methods, such as screen analysis or image
analysis are suitable for determining the median particle size and
the particle size distribution. A measure used for the breadth of
the particle size distribution is the ratio formed from 90 % value
(.O slashed.(90)) and the 10% value (.O slashed.(10)) from the
volume distribution.
[0151] The 90% value (.O slashed.(90)) gives that diameter which is
greater than the diameter of 90% of the particles. Correspondingly,
the diameter of the 10% value (.O slashed.(10)) exceeds that of 10%
of the particles. Particle size distribution of .O slashed.(90)/.O
slashed.(10).ltoreq.1.5, particularly .O slashed.(90)/.O
slashed.(10).ltoreq.1.25, are preferred.
[0152] Determination of the Amounts of Basic and Weakly Acidic
Groups
[0153] 50 ml of exchanger in the as-delivered form are shaken into
a 100 ml measuring cylinder on a vibrating table under deionized
water and flushed into a filter tube. 500 ml of 2% strength by
weight sodium hydroxide solution are added in the course of 50
minutes. The exchanger is then washed with tetrahydrofuran in 100
ml portions. From the second portion, the eluate is collected
separately in Erlenmeyer flasks and titrated against
phenolphthalein from pink to colorless using 0.1 normal
hydrochloric acid. Washing ends when the effluent no longer gives a
color with phenolphthalein or only 0.1 ml of 0.1 normal HCl is
required to titrate from pink to colorless. Then, in succession,
300 ml of 1 normal HCl and 300 ml of tetrahydrofuran are filtered
through each in the course of 30 minutes. The effluent is collected
in a 1 liter measuring flask, made up to the mark with deionized
water and mixed. 10 ml of solution are diluted in a glass beaker
with 50 ml of deionized water and titrated with 0.1 n sodium
hydroxide solution to pH 4.3 using a pH electrode. When titration
is complete, the pH is adjusted to approximately 3 using 0.1 molar
HNO.sub.3, the solution is diluted with deionized water to a volume
of approximately 100 ml and the chloride is titrated with a silver
electrode and AgNO.sub.3.
[0154] HCl number: the HCl number is an index of the amount of
weakly basic groups in the resin dimension: moles of weakly basic
groups per liter of resin.
[0155] Determination of the HCl number
[0156] 300-(AgNO.sub.3-consumption.multidot.10)/50=mol/liter of
exchanger in the as-delivered form
[0157] NaOH number is an index of the amount of weakly acidic
groups in the resin dimension: moles weakly acidic groups per liter
of resin
[0158] Determination of the NaOH number
[0159]
(AgNO.sub.3-consumption.multidot.10)-(NaOH-consumption.multidot.10)-
.multidot.0.02=mol/liter of exchanger in the as-delivered form
[0160] Determination of the Amount of Weakly and Strongly Basic
Groups
[0161] 100 ml of anion exchanger are charged in a glass column in
the course of 1 hour and 40 minutes with 1000 ml of 2% strength by
weight sodium hydroxide solution. The resin is then washed with
deionized water to remove the excess of sodium hydroxide
solution.
[0162] Determination of the NaCl number
[0163] 50 ml of the exchanger in the free base form and washed to
neutrality are placed in a column and charged with 950 ml of 2.5%
strength by weight aqueous sodium chloride solution. The effluent
is collected, made up to 1 liter with deionized water and of this
50 ml is titrated with 0.1 n (=0.1 normal) hydrochloric acid. The
resin is washed with deionized water.
[0164] ml of 0.1 n hydrochloric acid consumed.multidot.4/100=NaCl
number in mol/l of resin.
[0165] Determination of the NaNO.sub.3 number
[0166] 950 ml of 2.5% strength by weight sodium nitrate solution
are then filtered through. The effluent is made up to 1000 ml with
deionized water. Of this one aliquot, 10 ml, is taken off and
analyzed for its chloride content by titration with mercury nitrate
solution.
[0167] ml of Hg (NO.sub.3) solution
consumed.multidot.factor/17.75=NaNO.su- b.3 number in mol/liter of
resin.
[0168] Determination of the HCl number
[0169] The resin is washed with deionized water and flushed into a
glass beaker. 100 ml of 1 n hydrochloric acid are added and the
mixture is allowed to stand for 30 minutes. The entire suspension
is flushed into a glass column. A further 100 ml of hydrochloric
acid are filtered through the resin. The resin is washed with
methanol. The effluent is made up to 1000 ml with deionized water.
Of this 50 ml are titrated with 1 n of sodium hydroxide
solution.
[0170] (20-ml of 1 n sodium hydroxide solution consumed)/5=HCl
number in mol/liter of resin.
[0171] The amount of strongly basic groups is equal to the sum of
NaNO.sub.3 number and HCl number.
[0172] The amount of weakly basic groups is equal to the HCl
number.
[0173] Number of Perfect Beads After Preparation
[0174] 100 beads are viewed under the microscope. The number of
beads which are cracked or splintered is determined. The number of
perfect beads is given by the difference between the number of
damaged beads and 100.
[0175] Determination of Resin Stability by the Rolling Test
[0176] The bead polymer to be tested is divided between two plastic
cloths in a uniform layer thickness. The cloths are placed on a
solid horizontally mounted support and subjected to 20 working
cycles in a rolling apparatus. One working cycle consists of
rolling carried out back and forth. After rolling, the number of
undamaged beads is determined by enumeration under the microscope
on representative samples (100 beads).
[0177] Swelling Stability Test
[0178] 25 ml of anion exchanger in the chloride form are charged
into a column. 4% strength by weight aqueous sodium hydroxide
solution, deionized water, 6% strength by weight hydrochloric acid
and again deionized water are successively placed into the column,
the sodium hydroxide solution and the hydrochloric acid flowing
from the top through the resin, and the deionized water being
pumped through the resin from the bottom. The treatment is
performed in timed cycles via a control apparatus. One working
cycle lasts 1 h. 20 working cycles are carried out. After the end
of the working cycles, 100 beads are counted from the resin sample.
The number of perfect beads which are not damaged by cracks or
splitters is determined.
[0179] Useable Capacity of Strongly Basic and Medium Strongly Basic
Anion Exchangers and Determination of the Amount of Wash Water
[0180] 1000 ml of anion exchanger in the chloride form, that is to
say the nitrogen atom bears chloride as counter ion, are charged
into a glass column. 2500 ml of 4% strength by weight sodium
hydroxide solution are filtered through the resin in 1 hour. The
resin is then washed with 2 liters of debased, that is to say
decationized, water. The amount of wash water which is required
until the eluate has a conductivity of 10 .mu.S/cm or 2 .mu.S/cm is
reported in bed volumes per liter of resin. Water having a total
anion hardness of 25 degrees German hardness is then filtered
through the resin at a rate of 10 liters per hour. In the eluate,
the hardness and the residual amount of salicylic acid are
analyzed. Charging is ended at a residual salicylic acid content of
.gtoreq.0.1 mg/l.
[0181] From the amount of water which is filtered through the
resin, the total anion hardness of the water filtered through and
the amount of packed resin, the number of grams of CaO that are
taken up per liter of resin is determined. The number of grams of
CaO is the utilizable capacity of the resin in the units grams of
CaO per liter of anion exchanger.
[0182] It should be understood that the preceding is merely a
detailed description of a few embodiments of this invention and
that numerous changes to the disclosed embodiments can be made in
accordance with the disclosure herein without departing from the
spirit or scope of the invention. The preceding description,
therefore, is not meant to limit the scope of the invention.
Rather, the scope of the invention is to be determined only by the
appended claims and their equivalents.
* * * * *