Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Woven fabric – Including a foamed layer or component
Patent
1997-09-09
1999-12-07
Copenheaver, Blaine
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Woven fabric
Including a foamed layer or component
427244, 427336, 427373, 427541, 4283055, 4283166, 4283179, 4283191, 428378, 428913, 442370, B32B 3300, C08J 704, D06M 15263, H01B 728
Patent
active
059983124
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF INVENTION
The present invention relates to a substrate provided with a super-absorbent material, to a method for the manufacture thereof, a method for manufacturing the super-absorbent material, in addition to the use of the substrate in different products.
DESCRIPTION OF THE RELATED ART
Super-absorbent materials used for a variety of applications have existed for decades. Such super-absorbent materials are capable of binding a multiple of their own weight in liquid, particularly water, sometimes up to five hundred times as much.
The super-absorbent capacity of such materials is based on swelling. The materials are at least partially cross-linked polymer chains containing a large number of COOH groups. Through contact with water or an aqueous liquid hydrogen atoms will split off and COO.sup.- groups will be formed. These negatively charged carboxylate groups repulse each other, whereby the cross-linked polymer forms a three-dimensional network, in which the water molecules are as it were captured. The water molecules are held in the super-absorbent material by means of hydrogen bridges. The (partial) cross-linking of the material is essential for the effectiveness thereof, since "separate" polymer chains would simply dissolve in the liquid instead of absorbing it.
Super-absorbent materials occur as powders or fibres. The advantage of powders is that they have a markedly higher absorption capacity than fibres due to their significantly larger surface area. Super-absorbent fibres are moreover more expensive.
Powders are usually applied to a substrate, which in turn is further processed into the end product. In particular cases powders are also directly processed. The great drawback of powder however is that it causes dusting and dust nuisance both in the manufacture of substrates coated with powder and in the processing of those substrates or the loose powders themselves. Dust nuisance is not only very unpleasant but also causes loss of material and therefore waste and is moreover bad for the health of those working with the powders.
It is therefore the object of the present invention to provide a substrate provided with a super-absorbent material which does not have the above stated drawbacks.
SUMMARY OF THE INVENTION
This is achieved by the invention by manufacturing the substrate by causing suitable monomers to polymerize in the presence of a catalyst in order to obtain a polymer solution, adding a cross-linking agent to obtain a pasty composition, subsequently applying the composition on or in a substrate and allowing the applied composition to dry and cross-link to obtain the substrate with the super-absorbent material.
In an alternative embodiment of the invention the polymer solution can also be prepared, instead of by polymerization, by dissolving already formed polymers in water or an aqueous solvent and only then adding the cross-linking agent. The thus obtained composition can then again be applied to a suitable substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic diagram of preparatory steps for manufacturing a super-absorbent powder according to prior art; and
FIG. 2 shows a schematic diagram of the process of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The conventional method for preparing a super-absorbent powder consists of adding together suitable monomers and a cross-linking agent and causing these to polymerize in the presence of a catalyst. The polymer obtained in this manner is gelled and dried and subsequently ground to powder. FIG. 1 shows a schematic outline of the prepatory steps for manufacturing a super-absorbent powder according to the prior art.
In the method according to the invention however, the cross-linking step is not performed during polymerization but only thereafter. Cross-linking takes place just before, during or after the application of the mixture of the polymer solution and the cross-linking agent. The material with super-absorbent properties is subsequently manufactured by drying. FIG. 2 shows
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Copenheaver Blaine
Stockhausen GmbH & Co. KG
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