Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1996-10-29
1999-04-27
Wilson, James O.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 56, 536 90, 536 91, 536 95, 536 96, 536 97, 536 98, 536 99, C08B 1100, C08B 1102, C08B 11193, C08B 1108
Patent
active
058980725
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a suspension of a water-soluble, cross-linked cellulose ether having a fairly low salt content. The suspension is advantageously produced by adding water to a composition in the form of a dry blend that contains the water-soluble, cross-linked cellulose ether and a salt.
Water-soluble, non-ionic cellulose ethers are used in many industrial processes, as well as in many consumer products. Thus, such ethers are used in mining, papermaking, water purification and textile treatment, as well as in paint compositions, cleaning agents and cosmetics. It is, however, difficult to dissolve pulverulent, water-soluble and non-ionic cellulose ethers, owing to their tendency to gel and agglomerate. 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 dispersing agent and/or a stabiliser. When mixing water in, the electrolyte content is reduced and the cellulose ethers are dissolved without any gelling or lump formation. The cellulose ethers thus suspended in water have proved well suited for use as intermediate product in industrial processes and in the making of consumer products.
European Patent Application 413 274 discloses an aqueous suspension of hydroxyethylcellulose. This suspension contains 8-28% by weight of water-soluble hydroxyethylcellulose; 20-35% by weight of potassium carbonate, based on the weight of potassium carbonate and water; 0.2-8% by weight of a wetting agent having an HLB value of 6-9; and 0.08-0.6% by weight of a water-soluble or water-swellable thickening agent, both contents being based on the total weight of the suspension. Also, European Patent Application 482 533 teaches the suspension of a non-ionic cellulose ether, such as hydrophobe-modified hydroxyethylcellulose, hydrophobe-modified ethyl hydroxyethylcellulose, methylcellulose and hydroxyethylcellulose, in an aqueous solution of sodium formate. It appears from the Examples that a gel, and not a liquid suspension, is obtained when the content of sodium formate is 20% by weight or 25% by weight of the total composition. According to this European patent application, sodium formate has to be present in an amount of at least 30% by weight if a suspension is to be obtained. However, even though stable and useful suspensions can be produced in accordance with these two European patent applications, these suspensions will contain unacceptably high contents of electrolyte.
European Patent Application 3 582 teaches a method for reducing the electrolyte content of suspensions of water-soluble, non-ionic cellulose ethers. According to the patent application, this is achieved by adding not only an electrolytic 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, either in solid or in colloidal state, may, however, have adverse effects later on when the suspension is to be used.
One object of the present invention is to provide a suspension of a cellulose ether of low salt content without the use of any water-insoluble metal oxides. Another object of the invention is to enable the production of suspensions having a low as well as a high content of cellulose ether. Yet another object of the invention is to enable simple and expedient production of the suspension at the place where it is to be used, thereby to avoid unnecessary transports of water.
According to the present invention, it has now been found that these objects are attained by an aqueous suspension of a water-soluble, non-ionic cellulose ether, which is cross-linked with glyoxal and has a turbidity point of 25-100.degree. C., preferably 30-80.degree. C., as measured in a 1% aqueous solution, and an electrolytic salt giving a pH value below 8.0, preferably below 7.5, in water and at the concentration used in the suspension. Conveniently, the cellulose ether is present in an amount of 6-36%, based on
REFERENCES:
patent: 3489719 (1970-01-01), Savage et al.
patent: 5268466 (1993-12-01), Burdick
Abstract, Derwent, JP 48026235.
Andersson Lars
Bostrom Peter
Akzo Nobel nv
Mancini Ralph J.
White Everett
Wilson James O.
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