Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1997-06-10
1998-11-17
Robinson, Douglas W.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 84, 536 90, 536 91, 536 95, 536 96, 536 99, 536100, C08B 1100, C08B 1108, C08B 11193, C08B 100
Patent
active
058378642
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/SE95/01362, which was filed Nov. 16, 1995.
The present invention relates to a method for producing a suspension of a nonionic cellulose ether that has no turbidity point by mixing the water forming part of the suspension with a dry mixture that contains a cellulose ether, which is cross-linked with glyoxal, and an electrolyte salt.
Water-soluble, nonionic cellulose ethers are used in many industrial processes as well as in various consumer goods. The fields of application include mining, paper production, water treatment, textile treatment, colour compositions, detergents and cosmetic products. However, it is difficult to dissolve pulverulent, water-soluble and nonionic cellulose ethers, owing to the powder having a tendency towards gelling and agglomeration. One way of solving this problem is to suspend the water-soluble cellulose ethers in water containing a considerable amount of electrolyte and, optionally, a dispersant and/or a stabiliser. When water is mixed in, the electrolyte content is reduced and the cellulose ethers are dissolved without any gelling or lump formation. The cellulose ethers suspended in water have proved to be well suited for use as intermediary products in industrial processes, as well as in the production of consumer goods.
Thus, European Patent Application 413 274 teaches an aqueous suspension of hydroxyethylcellulose, i.e. a cellulose ether having no turbidity point in water. This suspension contains a water-soluble hydroxyethylcellulose in an amount of 8-28% by weight and further contains 20-35% by weight of potassium carbonate, based on the weight of potassium carbonate and water, 0.2-8% by weight of a detergent having a HLB value of 6-9, as well as 0.08-0.6% by weight of a water-soluble or water-swellable thickener, both contents being based on the weight of the total suspension.
European Patent Application 482 533 further discloses the suspension of a nonionic cellulose ether, such as hydrophobe-modified hydroxyethylcellulose, hydrophobe-modified ethyl-hydroxyethylcellulose, methylcellulose and hydroxyethylcellulose, in an aqueous sodium formate solution. It appears from the Examples that the amount of sodium formate should be at least 30% by weight, if one is to obtain a suspension.
Further, European Patent Application 3 582 discloses a method of reducing the electrolyte content of the suspension of water-soluble nonionic cellulose ethers. According to the European application, this is achieved by adding not only an electrolyte salt but also an aluminium oxide compound. Owing to the addition of aluminium oxide, the electrolyte content may, according to the patent application, be reduced from about 25% to 10%. The presence of aluminium oxide in solid or colloidal state may, however, have adverse effects when the suspension is used at a later stage.
One object of the present invention is to provide a method for suspending a cellulose ether, which has no turbidity point in water, together with an electrolyte salt and optionally other ingredients, such as a stabiliser and/or a dispersant, directly in the aqueous phase without there being any gelling. The invention thus provides a simple and reliable method for producing the suspension.
According to the invention, it has now been found that this object can be attained by producing an aqueous suspension of a water-soluble nonionic cellulose ether, which has no turbidity point in water. This is achieved by preparing a dry mixture which contains the nonionic cellulose ether cross-linked with glyoxal, as well as an electrolyte salt consisting of a salt or a mixture of salts which, in water and at the concentration used in the suspension, results in a pH value below 8.0, preferably below 7.5, and mixing the water forming part of the suspension with the dry mixture. Conveniently, the cellulose ether constitutes 8-25% by weight of the suspension, whereas the electrolyte salt is present in an amount of 20-45% by weight of the suspension, preferably 25-40%. Apart from the cellulose ether and the electro
REFERENCES:
patent: 3356519 (1967-12-01), Chambers et al.
patent: 3926951 (1975-12-01), Lindenfors et al.
Water-soluble cellulose ethers with high solubility, Wood Products, vol. 79, 1973.
Andersson Lars
Bostrom Peter
Akzo Nobel nv
Mancini Ralph J.
Robinson Douglas W.
White Everett
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