Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Ion-exchange polymer or process of preparing
Reexamination Certificate
2000-08-21
2004-03-02
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Ion-exchange polymer or process of preparing
C521S032000, C521S039000
Reexamination Certificate
active
06699913
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for preparing novel monodisperse anion exchangers whose strongly basic functional groups are either in the center of the resin particle or in the shell of the resin particle, as well as to their use.
U.S. Pat. No. 4,444,961 discloses, inter alia, a process for preparing monodisperse anion exchangers. Here, haloalkylated polymers are reacted with an alkylamine.
EP-A 46,535 describes, with reference to U.S. Pat. No. 3,989,650, the preparation of monodisperse, macroporous strongly basic anion exchangers of uniform particle size by a direct spraying and micro-encapsulation process.
EP-A 351,621 discloses the preparation of bifunctional hetero-disperse anion exchangers whose strongly basic functional groups are distributed in the center of the resin particle and in the shell of the resin particle.
Starting from this prior art, the object of the present invention was to provide a method for preparing monodisperse anion exchangers, preferably monodisperse macroporous anion exchangers with a high mechanical and osmotic stability of the beads, with an improved absorption capacity for anions, and at the same time with the strongly basic functional groups distributed either in the center of the resin particle or in the shell of the resin particle.
SUMMARY OF THE INVENTION
The present invention provides a process for preparing monodisperse anion exchangers having strongly basic functional groups distributed either in the center of the resin particle or in the shell of the resin particle comprising
(a) reacting monomer droplets made from at least one monovinylaromatic compound and at least one polyvinylaromatic compound, and, if desired, a porogen and/or, if desired, an initiator or an initiator combination to give a monodisperse, crosslinked bead polymer,
(b) amidomethylating the monodisperse, crosslinked bead polymer from step (a) with phthalimide derivatives,
(c) converting the amidomethylated bead polymer from step (b) to an aminomethylated bead polymer,
(d) Leuckart-Wallach-alkylating the aminomethylated bead polymer from step (c) to give a weakly basic anion exchanger having tertiary amino groups,
(e) partially loading the weakly basic anion exchanger from step (d) using a strong acid, and
(f) quaternizing the partially loaded weakly basic anion exchanger from step (e).
DETAILED DESCRIPTION OF THE INVENTION
Surprisingly, the monodisperse anion exchangers prepared according to the present invention have a higher utilizable capacity when in use, lower pressure loss, and higher osmotic and mechanical stability than the resins known from the above-mentioned prior art, in particular from EP-A 351,621.
The monodisperse, crosslinked vinylaromatic base polymer according to process step (a) may be prepared by the processes known from the literature. Processes of this type are described, for example, in U.S. Pat. No. 4,444,961, EP-A 46,535, U.S. Pat. No. 4,419,245, or WO 93/12167, the contents of which are incorporated into the present application by way of reference in relation to process step (a).
In process step (a), at least one monovinylaromatic compound and at least one polyvinylaromatic compound are used. However, it is also possible to use mixtures of two or more monovinylaromatic compounds and mixtures of two or more polyvinylaromatic compounds.
Preferred monovinylaromatic compounds for the purposes of the present invention in process step (a) are monoethylenically unsaturated compounds, such as styrene, vinyltoluene, ethylstyrene, &agr;-methylstyrene, chlorostyrene, chloromethylstyrene, alkyl acrylates, and alkyl methacrylates. Particular preference is given to the use of styrene or mixtures of styrene with the above-mentioned monomers.
Preferred polyvinylaromatic compounds for the purposes of the present invention for process step (a) are multifunctional ethylenically unsaturated compounds, such as divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene, trivinylnaphthalene, 1,7-octadiene, 1,5-hexadiene, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, or allyl methacrylate.
The amounts used of the polyvinylaromatic compounds are generally from 1 to 20% by weight (preferably from 2 to 12% by weight, particularly preferably from 4 to 10% by weight), based on the monomer or its mixture with other monomers. The nature of the polyvinylaromatic compounds (crosslinking agents) is selected with the subsequent use of the spherical polymer in mind. In many cases divinylbenzene is suitable. For most uses, commercial qualities of divinylbenzene are sufficient, and comprise ethylvinylbenzene besides the divinylbenzene isomers.
In one preferred embodiment of the present invention, micro-encapsulated monomer droplets are used in process step (a).
Possible materials for the microencapsulation of the monomer droplets are those known for use as complex coacervates, in particular polyesters, natural or synthetic polyamides, polyurethanes, and polyureas.
An example of a particularly suitable natural polyamide is gelatin, which is used in particular as coacervate and complex coacervate. For the purposes of the present invention, gelatin-containing complex coacervates are primarily combinations of gelatin with synthetic polyelectrolytes. Suitable synthetic polyelectrolytes are copolymers incorporating units of, for example, maleic acid, acrylic acid, methacrylic acid, acrylamide, or methacrylamide. Particular preference is given to the use of acrylic acid and acrylamide. Gelatin-containing capsules may be hardened using conventional hardeners, such as formaldehyde or glutaric dialdehyde. The encapsulation of monomer droplets with gelatin, with gelatin-containing coacervates and with gelatin-containing complex coacervates is described in detail in EP-A 46,535. The methods for encapsulation using synthetic polymers are known. An example of a highly suitable process is interfacial condensation, in which a reactive component dissolved in the monomer droplet (for example, an isocyanate or an acid chloride) is reacted with a second reactive component dissolved in the aqueous phase (for example, an amine).
The monomer droplets, which may be microencapsulated if desired, may, if desired, contain an initiator or mixtures of initiators to initiate the polymerization. Examples of initiators suitable for the novel process are 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-ethylhexanoyl-peroxy)-2,5-dimethylhexane, and tert-amylperoxy-2-ethylhexane, and azo compounds, such as 2,2′-azobis(isobutyronitrile) and 2,2′-azobis(2-methyl-isobutyronitrile).
The amounts used of the initiators are generally from 0.05 to 2.5% by weight (preferably from 0.1 to 1.5% by weight), based on the mixture of monomers.
To create a macroporous structure in the spherical polymer it is possible, if desired, to use porogens as other additives in the optionally microencapsulated monomer droplets. Suitable compounds for this purpose are organic solvents which are poor solvents and, respectively, swelling agents with respect to the polymer produced. Examples that may be mentioned are hexane, octane, isooctane, isododecane, methyl ethyl ketone, butanol, and octanol and isomers thereof.
The concepts “microporous” or “gel” and “macroporous” have been described in detail in the technical literature.
Substances that are monodisperse for the purposes of the present application are those for which the diameter of at least 90% by volume or by weight of the particles varies from the most frequent diameter by not more than 10% of the most frequent diameter.
For example, in the case of a substance with a most frequent diameter of 0.5 mm, at least 90% by volume or by weight have a size range from 0.45 to 0.55 mm, and in the case of a substance with a most frequent diameter of 0.7 mm, at least 90% by weight or by volume have a size range from 0.77 mm to 0.63 mm.
Bead polymers preferred for the purp
Klipper Reinhold
Lütjens Holger
Mitschker Alfred
Schnegg Ulrich
Seidel Rüdiger
Akorli Godfried R.
Eyl Diderico van
Lipman Bernard
LandOfFree
Process for preparing monodisperse anion exchangers having... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for preparing monodisperse anion exchangers having..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing monodisperse anion exchangers having... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3193075