Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Patent
1999-10-29
2000-10-31
Ogden, Necholus
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
510446, 510457, 510458, 510495, 510535, 510536, 23313FB, 159 481, 562 45, 562 97, C11D 1100
Patent
active
061403024
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an improved process for the production of anionic surfactant granules in which water-containing anionic surfactant pastes in their acidic form are subjected at a defined solids content to simultaneous neutralization, drying and granulation in a thin-layer evaporator or dryer.
1. Prior Art
Anionic surfactants are normally produced in several process steps. The sulfonation step is followed by neutralization with lyes in an aqueous medium and, finally, the water is removed to the required content in a concluding drying step. The production costs are determined to a very large extent by the quantity of water which ultimately has to be removed from the product. It will readily be appreciated that every effort should be made to keep this quantity as small as possible and, if possible, to eliminate the need for the drying step altogether.
Accordingly, various attempts have been made in the past to provide such processes and to improve process economy by reducing the energy costs and increasing the throughput. However, reducing the water content in the neutralization step leads through gel formation to a steep increase in the viscosity of the products which is accompanied by inhomogeneities in the product through inadequate mixing of the acidic anionic surfactant and the base used for neutralization. Accordingly, highly concentrated anionic surfactant pastes with residual water contents of at least 25 to 35% by weight can still just be produced and dried in correspondingly adapted industrial installations.
Another approach based on a different concept is to integrate neutralization and drying into a single process step. German patent application DE-A1 3741401 (Henkel) describes a process in which aqueous acidic anionic surfactants and aqueous neutralization bases are exposed to a gas stream and then dried by spraying. International patent application WO 96/06917 (Unilever) describes a process for the production of anionic surfactant granules in which water-containing, acidic anionic surfactants are mixed with water-containing neutralizing agents in a horizontally arranged thin-layer evaporator or dryer, so that neutralized preparations with a water content above 20% by weight are formed and are subsequently dried at temperatures above 130.degree. C. to the required water content of less than 20% by weight and, at the same time, granulated. The high water content in the neutralization step is unfavorable from the energy point of view and, in addition, leads to a comparatively low throughput. Balancing of the described neutralization of aqueous alkyl sulfuric acid semiester with 30% by weight sodium hydroxide shows that a product with a total water content of at least 25% by weight is formed in the meantime and is then dried.
By contrast, International patent application WO 96/06916 (Unilever) describes a process for drying water-containing anionic surfactant pastes in a horizontal thin-layer evaporator which is carried out at temperatures above 130.degree. C. under a light vacuum to almost normal pressure. Another feature of this process is the use of a very high peripheral speed of the stirrers used of at least 15 m/s which virtually rules out direct wall contact and leads to light-colored products. However, in the drying of water-containing anionic surfactant pastes, more particularly water-containing pastes of alkyl sulfates or alkyl ether sulfates, there is basically a danger of unwanted hydrolysis in the product. Even a brief local reduction in the pH value leads in the presence of water to re-hydrolysis, to the formation of inorganic sulfate and to a reduction in the content of washing-active substance. In following the teaching of WO 96/06916, applicants found that a hydrolysis-free product could not be reproducibly obtained over an operating period of several hours.
Accordingly, the problem addressed by the present invention was to provide a process for the production of anionic surfactant granules by simultaneous neutralization, drying and granulation which
REFERENCES:
patent: 5189207 (1993-02-01), Blasey et al.
Surfactants in Consumer Products (1987) pp. 54-127.
Katalysatoren, Tenside and Mineraloeladditive (1978) pp. 123-217.
Gutsche Bernhard
Lueder Thomas
Scholinakis Konstantinos
Cognis Deutschland GmbH
Drach John E.
Millson Jr. Henry E.
Ogden Necholus
LandOfFree
Method for producing anionic surfactant granulates does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing anionic surfactant granulates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing anionic surfactant granulates will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2051848