Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1997-04-04
2003-07-01
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S329400, C525S329900, C526S306000, C526S307600, C526S318500
Reexamination Certificate
active
06586534
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to agglomerated particles of finely divided, water-soluble or water-swellable polymers which contain ammonium carboxylate groups and at least 50% by weight of a monoethylenically unsaturated carboxylic acid as polymerized units, the agglomerated particles having a mean particle diameter of from 20 to 2500 &mgr;m and consisting of primary particles having a mean particle diameter of from 0.1 to 15 &mgr;m, which are obtainable by polymerization of monomer mixtures of at least 50% by weight of a monoethylenically unsaturated carboxylic acid, in the presence or absence of other monomers and of crosslinking agents, by a water-in-oil polymerization method and can be prepared by azeotropic removal of water from the water-in-oil polymer emulsion containing the primary particles, in the presence of polyalkylene glycols which have an agglomerating effect and which
a) are obtainable by an addition reaction of C
2
-C
4
-alkylene oxides with alcohols, phenols, amines or carboxylic acids and
b) contain at least two polymerized alkylene oxide units,
and the agglomerated polymer particles disintegrating into the primary particles on introduction into an aqueous medium, processes for the preparation of the agglomerated polymer particles by the azeotropic removal of water from water-in-oil emulsions of water-soluble or water-swellable polymers which contain ammonium carboxylate groups and have a mean particle diameter of from 0.1 to 15 &mgr;m, in the presence of from 0.1 to 40% by weight, based on the polymers, of polyalkylene glycols which have an agglomerating effect and which
a) are obtainable by an addition reaction of C
2
-C
4
-alkylene oxides with alcohols, phenols, amines or carboxylic acids and
b) contain at least two polymerized alkylene oxide units,
and isolation of the particles, and the use of the agglomerated polymer particles as thickeners for pigment print pastes.
2. Description of the Background
G-A-1 319 632 discloses a process for the preparation of granular polymers in which first of all a water-in-oil emulsion of a water-soluble monomer in an organic solvent is prepared, the emulsion containing ethylcellulose or polyvinyl acetate and a water-soluble emulsifier comprising a condensate of ethylene oxide or propylene oxide and alcohols, amines, amides, fatty acids or phenols. The water-in-oil emulsion is subsequently polymerized in the presence of initiators and then dewatered by azeotropic distillation. The granular polymer is filtered off. It has a particle size of from about 1 to 6 mm. Such coarse-particled polymers dissolve only very slowly in water.
WO-A-92/13912 discloses agglomerated particles of water-soluble or water-swellable polymers having a mean particle diameter of from 20 to 5000 &mgr;m. The agglomerated polymer particles consist of primary particles having a mean diameter of from 0.1 to 15 &mgr;m and are prepared by polymerization of water-soluble monomers, in the presence or absence of crosslinking agents, by a water-in-oil polymerization method and subsequent azeotropic removal of water from the water-in-oil polymer emulsion containing the primary particles in the presence of polyalkylene glycols which have an agglomerating effect and which
a) are obtainable by an addition reaction of C
2
-C
4
-alkylene oxides with alcohols, phenols, amines or carboxylic acids and
b) contain at least two polymerized alkylene oxide units.
The agglomerated polymer particles disintegrate into the primary particles on introduction into an aqueous medium. However, difficulties occur in the azeotropic removal of water from polymers which contain ammonium carboxylate groups because different amounts of ammonia simultaneously evaporate depending on the duration of removal, leading to a nonreproducible degree of hydrolysis of the polymer. Consequently, the polymer is quantitatively deposited on the wall of the kettle used for removal of water until the stirrer ceases to rotate.
Moreover, it is difficult to establish the particle size of the agglomerated polymers in a controlled manner.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide agglomerated particles of finely divided, water-soluble or water-swellable polymers containing ammonium carboxylate groups and a process for their preparation. The polymers should have a narrow particle size distribution, the maximum of the particle size distribution being readily variable by changing the process conditions in the preparation.
SUMMARY OF THE INVENTION
We have found that this object is achieved, according to the invention, by agglomerated particles of finely divided, water-soluble or water-swellable polymers which contain ammonium carboxylate groups and at least 50% by weight of a monoethylenically unsaturated carboxylic acid as polymerized units, the agglomerated polymer particles having a mean particle diameter of from 20 to 2500 &mgr;m and consisting of primary particles having a mean diameter of from 0.1 to 15 &mgr;m, which are obtainable by polymerization of monomer mixtures of at least 50% by weight of monoethylenically unsaturated carboxylic acids in the presence or absence of other monoethylenically unsaturated monomers and crosslinking agents by a water-in-oil polymerization method and can be prepared by azeotropic removal of water from the water-in-oil polymer emulsion containing the primary particles, in the presence of polyalkylene glycols which have an agglomerating effect and which
a) are obtainable by an addition reaction of C
2
-C
4
-alkylene oxides with alcohols, phenols, amines or carboxylic acids and
b) contain at least two polymerized alkylene oxide units,
and the agglomerated polymer particles disintegrating into the primary particles on introduction into an aqueous medium, if the azeotropic removal of water is additionally carried out in the presence of from 0.1 to 20% by weight, based on the polymers, of protective colloids which are obtainable by free radical copolymerization of
a) C
8
-C
40
-monoolefins with
b) monoethylenically unsaturated C
4
-C
6
-dicarboxylic anhydrides
by a mass polymerization method at from 80 to 300° C. to give copolymers having molecular weights of from 500 to 20,000 g/mol.
The present invention furthermore relates to a process for the preparation of agglomerated polymer particles by azeotropic removal of water from water-in-oil emulsions of water-soluble or water-swellable polymers which contain ammonium carboxylate groups and have a mean particle diameter of from 0.1 to 15 &mgr;m, in the presence of from 0.1 to 40% by weight, based on the polymers, of polyalkylene glycols which have an agglomerating effect and which
a) are obtainable by an addition reaction of C
2
-C
4
-alkylene oxides with alcohols, phenols, amines or carboxylic acids and
b) contain at least two polymerized alkylene oxide units,
and isolation of the particles, if the azeotropic removal of water is additionally carried out in the presence of from 0.1 to 20% by weight, based on the polymers, of protective colloids which are obtainable by free radical copolymerization of
a) C
8
-C
40
-monoolefins with
b) monoethylenically unsaturated C
4
-C
6
-dicarboxylic anhydrides
by a mass polymerization method at from 80 to 300° C. to give copolymers having molecular weights of from 500 to 20,000 g/mol.
DETAILED DESCRIPTION OF THE INVENTION
In order to obtain the novel agglomerated polymer particles, it is possible either first to polymerize monomer mixtures which contain at least 50% by weight of a monoethylenically unsaturated carboxylic acid and, if required, other monoethylenically unsaturated monomers and, if required, crosslinking agents, the carboxylic acids being, if required, in the form partly or completely neutralized with ammonia, by the known water-in-oil polymerization method or, if such water-in-oil polymer emulsions are available, to start directly from these and to remove water azeotropically from the emulsions in the presence of the polyalkylene glycols which have an agglomerating effect and the protective c
Denzinger Walter
Hartmann Heinrich
Kistenmacher Axel
Nieberle Jürgen
Rübenacker Martin
BASF - Aktiengesellschaft
Lipman Bernard
LandOfFree
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