JPH0429604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to stabilized aqueous suspensions of synthesized zeolites, in particular zeolite A, and low phosphate and phosphate unsaturated suspensions optionally containing active chlorine. It relates to the use of said suspension for the production of powder-containing detergents and cleaning agents. Conventional technology Synthetic zeolite type A, especially zeolite NaA
The use of sulfuric acid as a builder in detergents and thus as a substitute for sodium tripolyphosphate in detergents and detergents has become increasingly important in recent years. Thus, a number of detergents containing zeolites with low phosphate and phosphate-free formulations already appear on the market. However, the use of zeolite A as a new water-insoluble cleaning agent component on an industrial scale has also led to new developments in the cleaning and cleaning agent industry. In this case, particular attention is given to processing the zeolite in the form of a storage-stable, well-flowing suspension containing as much zeolite as possible.
[For the production of zeolite-containing detergents, especially with the use of stabilized zeolite suspensions, see O. Koch: Seifen-O¨le-Fett-Wachse 106
(1980), pp. 321-324]. A number of stabilizers have already been proposed for the stabilization of aqueous zeolite suspensions which remain free-flowing after storage and transport and can be stirred and discharged via pipes. For example, in West German Patent Application No. 2527388, macromolecular organic polymer compounds having a molecular weight exceeding 1500 and containing carboxyl groups and/or hydroxyl groups are used as stabilizers.
Among others, those derived from natural products such as polysaccharides are described. For the stabilization of aqueous suspensions containing more than 40% by weight of zeolites, these stabilizers must be used in amounts of 0.5 to 6.0% by weight. Problems to be Solved by the Invention The object of the present invention is to find a stabilizer for stabilizing the suspension more effectively. Means to solve the problem By the way, industrially produced zeolite A
Stabilized aqueous zeolite suspensions consisting of type, water and macromolecular organic polymeric compounds with a molecular weight above 1500 and containing carboxyl and/or hydroxyl groups as stabilizers derived from natural products It has been found that a significant improvement can be achieved when using the polysaccharide xanthan gum. The amount of said suspension stabilizer is present in the suspension according to the invention in the range from 0.05 to 0.20% by weight, preferably from 0.10 to 0.15% by weight, based on the total stabilized aqueous zeolite suspension. Although such small amounts of stabilizers for zeolite suspensions are already known from German patent application no. Polyacrylamide or its copolymer. According to the invention, the content of zeolite may be up to 60% by weight, preferably from 40 to 55% by weight, based on the total stabilized aqueous zeolite suspension. In this specification, "xanthan gum" means RO¨mpps Chemie-
Lexikon, 7th edition, pages 1355-1356 and Kirk-
Othmer“Encyclopedia of Chemical
According to ``Xanthan Technology'', 3rd edition (1980), volume 12, pages 62-64, the Anglo-Saxon name ``
Xanthan gum is a polymeric polysaccharide, an extracellular heteropolysaccharide with a molecular weight of approximately 2,000,000 or more, produced from various xanthomonas bacteria, such as Xanthomonas campestris. It is a hydrophilic colloid. There are numerous publications on the production of xanthan gum by the growth and cultivation of Xanthomonas bacteria in aqueous media. The underlying research is published in U.S. Pat.
It is described in the specification of No. 3000790. Hydrophilic colloids produced from Xanthomonas campestris include mannose, glucose,
It is a polysaccharide containing glucuronic acid, an o-acetyl group, and acetyl-bound pyruvate. The polysaccharides arise as extracellular reaction products during aerobic cultivation of the bacterial species in an aqueous culture medium which, in addition to the customary growth-promoting components, contains in particular water-soluble carbohydrate compounds. Products of this type are commercially available, for example sold under the name Kelzan by Kelco Comp., Oklahoma, USA. This product is represented by the formula: The zeolite A used according to the invention can be produced by a number of known methods, for example by precipitation of a solution of sodium silicate and sodium aluminate and subsequent hydrothermal treatment, or by hydrothermal treatment of sulfurized kaolin and sodium hydroxide. can do. Many methods are known for the industrial production of zeolite A for detergents, and in the case of these known methods,
Zeolite-A crystals with rounded corners and edges are obtained and the formation of oversized particles (grit) is avoided by the specific process parameters. Such a method is described, for example, in West German Patent Application Publication No. 2447021.
No. 2517218, No. 2533614, No. 2533614, No. 2517218, No. 2533614, No.
No. 2651414, No. 2651420, No. 2651436, No. 2651445, No. 2651485, No. 2704310,
It is described in the specifications of the same No. 2734296, the same No. 2941636, the same No. 3011834, and the same No. 3021370. Zeolite A generally has a water content of about 40-60% during synthesis.
Resulting as a wet filter cake. Due to its thixotropic nature, the filter cake can be easily stirred, and suspension stabilizers may also be added directly. The suspension according to the invention has a low viscosity at room temperature and up to 50° C. and can be pumped and stirred up to 7 days of storage. Even after unlimited continuous storage at room temperature, only a small amount of soft sediment forms, which can be immediately stirred again. However, in addition to good stability at room temperature, the suspensions according to the invention also exhibit excellent rheological properties at elevated temperatures, ie at temperatures of 50 to 80 DEG C. In many industrial installations for processing zeolite suspensions for the production of powdered detergents, the zeolite suspensions are heated, i.e. at 50 °C.
must be used at temperatures exceeding It is crucial for its usefulness that the suspension is stable for a relatively long time at the temperature mentioned and does not decompose. Also, the PH value of the aqueous zeolite suspension of approximately PH 11-14 is not significantly changed by the neutral reactive stabilizer according to the invention. The stabilizer used according to the invention naturally does not have a negative effect on the calcium binding capacity and contains active chlorine, although the sensitivity of xanthan gum to strong oxidizing agents such as hypochlorous acid is known. When using the suspension according to the invention for the production of dishwashing detergents, no damage could be observed. Suspensions according to the invention can therefore be prepared by simply mixing the components. In practice, it is still wet due to its manufacture.
An aqueous suspension of undried zeolite is used, in which case the wet filter cake obtained after separation of the mother liquor and washing with water is converted by stirring into a fluid suspension. Generally no further water needs to be added. The stabilizer added according to the invention is used in the form of a pale yellow powder. Suspensions according to the invention can be prepared with zeolite concentrations of at least 20% by weight. Of course, for economic reasons, eg to save transport and energy costs, the water content in the suspension must be as low as possible. That is, it is desirable to adjust the zeolite content to a value exceeding 40% by weight, and preferably to a value exceeding 50% by weight. In the preparation of the suspensions according to the invention, elevated temperatures, ie approximately 60° C., are generally employed, which facilitates the mixing operation. In the preparation of the suspension according to the invention, it is of course also possible to use already dried zeolite powder, if a still moist filter cake of zeolite is not used for its preparation. For further processing to obtain detergents and cleaning agents, the stabilized zeolide suspension is used as liquid raw material according to the customary production methods for such drugs. It should also be noted that the foaming properties of detergents and cleaners are not negatively affected by the addition of the suspension. However, the stabilized zeolite suspension can also be converted into a powder which can easily be dispersed again in water by conventional drying means, for example by spray drying. When preparing pulverulent detergents using the suspensions according to the invention, especially by spray-drying methods, very dust-free products are obtained which can be easily used.
The suspensions according to the invention are also suitable for the production of powdered dishwashing detergents. EXAMPLE A wet filter cake of zeolite NaA was used for the production of a stabilized suspension with the following properties: Content of zeolite NaA relative to anhydride (ignition residue after heating to 800° C. for 1 hour): 47.0%, Calcium binding capacity: 155-157 mgCaO/g anhydrous (measured by the method below), Particle size distribution (Coulter counter, volume distribution): 100% less than 15μ; 98.1% less than 10μ; 5μ
less than 79%; less than 3μ 36.5%; average particle size: 3.9μ, alkaline content: 0.35% by weight Method for measuring calcium binding capacity Aqueous solution 1 containing 0.594 g of CaCl ₂ (300 mgCaO / = 30 ° d) was diluted with hydroxide. The pH was adjusted to 10 using sodium solution, and 2.13 g of filter cake (=1.00 g of anhydrous zeolite A) was added thereto while stirring. This suspension was then stirred for 10 minutes at room temperature of 22±2°C. After the zeolite was filtered off, the residual hardness X in the filtrate was measured by complex titration using ethylenediaminetetraacetic acid. Then the formula: (30-X)・10
Calcium binding capacity (mgCaO/g) is calculated. General method for producing stabilized zeolite suspensions: Filter cake of wet zeolite A (approximately 50% water
% by weight) each batch of 2 kg was stirred at 60°C.
The stirring strength of the MIG stirrer was 500 rpm. Under these conditions, the filter cake was transformed into a well-stirrable suspension. Stabilizers were gradually introduced into this suspension. After about 10 minutes a homogeneous suspension containing the stabilizer was obtained without the formation of lumps. Next, the viscosity (mPa.s) was measured at 20°C and 50°C using a B-type viscometer with a spindle speed of 20 rpm. In addition, the suspension was evaluated for sediment formation and sediment consistency based on sedimentation. The evaluation of suspensions is carried out empirically, ie without being based on precisely measurable values, and can therefore be carried out in each case by direct comparison within a series of experiments. Furthermore, when a mixture of zeolite A and hydrosodalite or a mixture of zeolite A and zeolite Comparable stability properties were observed. Test method A 250 ml screw cap glass was used as the container for the storage test. The injection height of the newly injected suspension
It was set as 100%. The height of the clear liquid zone above the suspension was measured and the sedimentation behavior was expressed in "% suspension". "100% suspension" therefore means that no clear liquid phase was formed. Also in the same containers, the consistency of the sediment formed after storage was checked by contacting with a glass rod. Sediment determination is performed not only on the presence or absence of sediment formation and its extent, but also on whether re-stirring of the sediment is easy, difficult, or impossible. The following rating was therefore chosen: B _F = no sediment in the suspension. B _W = Formation of sediment with soft consistency, easy to stir. B _M = formation of a sediment with medium consistency;
Difficult to stir. B _H = formation of a sediment with a hard consistency, not stirrable. The experimental results are listed in the table below. These results are
It is shown that the suspension according to the invention is stable even at high temperatures and can continue to be processed satisfactorily even after storage. 【table】

Claims (1)

[Scope of Claims] 1. A stabilized aqueous zeolite suspension consisting of an industrially produced zeolite, water and, as a stabilizer, a macromolecular organic polymer compound with a molecular weight range of more than 1500 having carboxyl and/or hydroxyl groups. A stabilized aqueous zeolite suspension, characterized in that the suspension contains the polysaccharide xanthan gum as a stabilizer. 2 0.01 for the suspension stabilized aqueous zeolite
Suspension according to claim 1, containing stabilizers in an amount of ~0.25% by weight, preferably 0.05-0.20% by weight. 3. The suspension contains up to 60% by weight, preferably 40-55% by weight of the total stabilized aqueous zeolite suspension.
The suspension according to claim 1 or 2, which contains a zeolite.