Compositions: coating or plastic – Coating or plastic compositions – Carbohydrate or derivative containing
Patent
1994-10-07
1996-01-30
Brunsman, David
Compositions: coating or plastic
Coating or plastic compositions
Carbohydrate or derivative containing
C09D10128
Patent
active
054877776
DESCRIPTION:
BRIEF SUMMARY
This is a filing under 35 U.S.C. 371 of PCT/FI93/00132 filed Mar. 30, 1993.
BACKGROUND OF THE INVENTION
The present invention relates to a carboxymethyl cellulose slurry and a process for the preparation thereof.
Carboxymethyl cellulose (CMC) is often used in the form of its sodium salt for modifying the rheologic properties of aqueous liquids. The applications to be considered are the clarification of water, the treatment of minerals, the thickening of foodstuffs and medication, the thickening of farm products, the use in oil drilling liquids, the use in building materials, such as concrete, the modification of ceramic materials, the modification of latex colours, the use in paper coating and the use as a protective colloid in emulsion and suspension polymerization.
CMC has conventionally been delivered in a dry, particulate form. The drawbacks thereof are the formation of dust, the poor dispersing in aqueous liquids and the long dissolution times when CMC is dissolved in water.
The same problems are encountered with the treatment of CMC type powders as generally with dry particulate materials. Since CMC type powders are hygroscopic and absorb moisture from the air their particles can therefore become agglomerated. It is very difficult to disperse agglomerated particles in aqueous liquids. The dissolution of CMC powder is difficult in other respects, too, since the powder tends, during dissolution, to form an agglomerate, the gel on the surface of which prevents water from penetrating into the dry powder inside the agglomerate and from dissolving it.
For the above-mentioned reasons, users of CMC products tend to require them in a form in which they can be easily dissolved in the aqueous system of their process.
The FI-application 885969 presents the delivery of CMC products e.g. in the form of such aqueous dispersions that contain particulate CMC product, polyethylene glycol having a low molecular mass (LWPEG), water and polyethylene glycol having a high molecular mass (HWPEG). LWPEG was defined in the publication as a substituted or non-substituted polyethylene glycol being liquid at room temperature and having a molar mass of about 200 to 700 g/mol. HWPEG was defined as a substituted or non-substituted polyethylene glycol being solid at room temperature and having a molar mass of over 3000 g/mol.
According to the examples of the publication the part of the CMC(Na-salt)-product in the whole mixture counts for 20 to 23% by weight. The part of LWPEG counts for 41 to 48% by weight, the part of water counts for 29 to 33% by weight and the part of HWPEG counts for 3 to 4.5% by weight. The molar masses of the LWPEG-samples used were 200, 300, and 400 g/mol. The molar mass of the HWPEG-samples used was 20,000 g/mol.
The drawback of the product presented in the FI-publication mentioned is that its maximum CMC content giving a sufficiently flowing but stable dispersion, is only about 20% by weight. Despite this, the product according to the publication has a very low dispersion stability. Of the CMC dispersions prepared in the examples only two were stable after 24 hours from the time of preparation. It is clear that such a product cannot be used after storage and transport without cumbersome redispersion.
SUMMARY OF THE INVENTION
The aim of the present invention is to remove these drawbacks, i.e. to provide a stable, concentrated, easily pumpable dispersion or slurry which allows the dissolution of the CMC product more quickly into water. Such a product is easily storable, transportable, pumpable and dissolvable in aqueous mixtures without the formation of precipitations or aggolomerates typical of the handling and treatment of dry powders.
The aims of the present invention have now been achieved by a new carboxymethyl cellulose slurry or dispersion, which is mainly characterized by what has been stated in the characterizing clause of claim 1. It thus has been realized that the above-mentioned usability can be achieved by adding to the carboxymethyl cellulose, LW polyethylene glycol having a molar mass of
REFERENCES:
patent: 3311577 (1967-03-01), Rankia
patent: 4561985 (1985-12-01), Glass, Jr.
patent: 4799962 (1989-01-01), Ahmad
Lahteenmaki Mikko J.
Lundan Arvo O.
Brunsman David
Metsa-Serla Chemicals Oy
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