Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1990-08-03
1993-09-28
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
525221, 427180, 427221, 427222, 528502, 428407, C08K 908
Patent
active
052487091
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to granular material of water-swellable polymers, a method for the manufacture thereof and its use for the absorption of aqueous solutions, especially body liquids, such as blood and/or urine.
2. Description of Related Art
Today, water-swellable polymers are being used in various manners, particularly in the hygienic field for the absorption of body liquids, such as blood and/or urine. The water-swellable polymers must be capable to bind large amounts of liquid (water or body liquids) within a very short period of time. These known water-swellable finely divided polymers, however, tend to "block", i.e. when contacting water or aqueous solutions the outer layer of the bed becomes sticky and thus prevents the liquid from further penetrating into the innermost of the absorbent.
The water-swellable powder-like finely divided polymers are obtained in a more or less wide spectrum of grain sizes, depending on the method of manufacture, said spectrum starting from fine sizes to coarser grains up to coarse-grains. A typical grain spectrum for a water-swellable polymer ground after drying is in the range of from 10 to 800 .mu.m, whereby the size fraction of 150 to 630 .mu.m is used as absorbent for practical purposes. The fine powder obtained having a grain size of about 10 to 150 .mu.m is too fine for the use as absorbent and is therefore to be regarded as waste, and, moreover, is an annoyance.
Therefore it is the object of the present invention to provide such water-swellable, powderlike polymers in a novel appearance not having the disadvantage of blocking, having the capacity of rapidly absorbing large amounts of liquids and which additionally may be produced in an easy and economical way.
SUMMARY OF THE INVENTION
According to the present invention this object is achieved by a granular material of a water-swellable polymer obtainable by agglomeration with agglomeration auxiliary substances, which, due to their ability to melt and soften, are capable of agglomerating the finely divided polymer particles.
The increase of grain size by agglomeration of finely dispersed materials is known per se. In order to build up granular material from powder particles many processes are available (Ullmann Encyclopedia of Technical Chemistry, 4th edition, vol. 18, page 157; Chem. Ind. 53 (1981), pages 37-41), said processes include sintering agglomeration and melting agglomeration. However, pelletizing of powder-like, water-swellable polymers has not been used in the art, up to now.
Surprisingly, the powdery water-swellable polymers may be agglomerated by heating mixtures having powder-like, meltable, thermoplastic and thermosetting substances as agglomeration auxiliary agents, whereby the stability of the agglomerates is increased and thus processing and use is considerably improved. Furthermore it is surprising that the granular material manufactured in this way does not tend to "block" but may absorb large amounts of liquid within a short period of time.
DESCRIPTION OF PREFERRED EMBODIMENTS
This surprising improvement of their properties can be recognized in all agglomerated water-swellable polymers, e.g., cross-linked homopolymers, copolymers and terpolymers of the acrylic and methacrylic acid, graft polymers of acryl derivatives on starch and cellulose products, polyurethanes, saponification products of cross-linked homopolymers and copolymers of the (meth)-acrylonitrile, the (meth)-acrylamide and acrylic esters, and copolymers of isobutylene and maleic acid anhydride. The polymers may contain further ionomeric and non-ionic momomers, such as, e.g., acrylamidopropanesulfonic acid, vinyl phosphonic acid, vinyl sulfonic acid, dialkylaminoalkyl(meth)-acrylates, dialkylaminoalkyl(meth)-acrylamides, quaternization products of monomers having tertiary amino groups, monomers containing one or more allyl groups, (meth)-acrylamide, alkyl(meth)-acrylamides, methylenebisacrylamide, monoacrylic-acid alkyl ester, diacrylic-acid alkyl ester, and tr
REFERENCES:
patent: 4190563 (1980-02-01), Bosley et al.
Chemische Fabrik Stockhausen GmbH
Michl Paul R.
Szekely Peter
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