Plastic and nonmetallic article shaping or treating: processes – Spheroidizing or rounding of solid particles
Patent
1992-02-19
1993-01-26
Theisen, Mary Lynn
Plastic and nonmetallic article shaping or treating: processes
Spheroidizing or rounding of solid particles
252 99, 25218631, 264118, 264122, B29B 900
Patent
active
051820544
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the production of inorganic peroxo compounds.
Inorganic peroxo compounds, particularly perborates, have long been used as oxidizing agents in bleaches, detergents and disinfectants. Whereas perborate tetrahydrate has hitherto mainly been used in detergents and bleaches, the monohydrate has also recently been acquiring increasing significance by virtue of its higher active oxygen content and its higher dissolving rate. According to present knowledge, these compounds are in reality the hexahydrate or rather the anhydrous form of cyclic sodium diperoxodiborate although the old names, perborate tetrahydrate (NaBO.sub.3.4 H.sub.2 O) and sodium perborate monohydrate (NaBO.sub.3.H.sub.2 O), are used in the following. The standard characterization based on the active oxygen content, according to which products containing more than 15% AO are termed monohydrate, is also retained in the following (theoretical active oxygen content of the monohydrate: 16.0% by weight).
2. Discussion of Related Art
In its production on an industrial scale from sodium borate and hydrogen peroxide, perborate tetrahydrate is generally obtained in the form of a coarsely crystalline, abrasion-resistant powder of relatively high apparent density. Accordingly, it can readily be incorporated in standard detergents. By contrast, perborate monohydrate, which is normally produced by drying from the perborate tetrahydrate, is a light porous material with little abrasion resistance which is difficult to incorporate in this form. Accordingly, there has been no shortage of attempts to eliminate these disadvantages of the monohydrate. One possibility in this regard is to granulate the perborate monohydrate. Thus, it is proposed in DE 26 50 225 to combine hydrogen peroxide and borate with simultaneous drying in a fluidized bed to form perborate monohydrate which accumulates in granular form providing the process is suitably managed. However, reliable adjustment of the process parameters is difficult. In other known processes, the tetrahydrate is first agglomerated with water and/or other granulation aids to form relatively large particles which are then dewatered in a following drying step to form perborate monohydrate granules (EP 202 519, Ep 295 950, EP 296 813 and earlier application DE-p 38 30 545.3 . One feature common to all these processes is that the granulated monohydrate is also obtained in a relatively light form, i.e. with a low apparent density. Accordingly, these forms of the monohydrate can only be used to a limited extent in modern detergents, which have very high apparent densities, because separation can occur. In addition, it is proposed in EP 102 419 to granulate perborates, particularly the oxoborate obtainable by heating of the monohydrate, by compaction. However, this process requires the addition of polytetrafluoroethylene as lubricant and gives a product unsuitable for detergents and bleaches, not the least because this additive is non-biodegradable.
Accordingly, the problem addressed by the present invention was to provide perborate monohydrate in a form suitable for use in modern detergents.
DESCRIPTION OF THE INVENTION
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term "about ".
According to the invention, this problem has been solved by a process in which perborate monohydrate is dry-compacted with addition of compacting aids selected from the group consisting of alkali metal salts, alkaline earth metal salts, carbohydrates, which may optionally be etherified, anionic surfactants and nonionic surfactants and is then size-reduced to the required degree. Compacting is preferably carried out between rollers.
Whereas perborate monohydrate can only be compacted to a limited extent in the absence of additives, the process according to the invention provides a product of high density whi
REFERENCES:
patent: 2979464 (1961-04-01), Pistor
patent: 4405486 (1983-09-01), Eoga
patent: 4695397 (1987-09-01), Sommer et al.
patent: 4894211 (1990-01-01), Condo et al.
patent: 4925382 (1990-05-01), Bergendahl et al.
Abstract of JP 60-112714.
Bauer Volker
Jacobs Jochen
Koester Klaus
Raehse Wilfried
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Szoke Ernest J.
Theisen Mary Lynn
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