Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
1999-09-08
2001-04-10
Gupta, Yogendra (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S376000, C252S186250
Reexamination Certificate
active
06214785
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present invention is described in the German priority application No. 19841184.7, filed Sep. 09, 1998, which is hereby incorporated by reference as fully disclosed herein.
DESCRIPTION OF THE RELATED ART
Bleach activators are important constituents in compact detergents, stain removal salts and dishwashing detergents. At from 40° C. to 60° C., they permit a bleaching result which is comparable with a boil wash, by reacting with hydrogen peroxide donors (in most cases perborates or percarbonates) to release an organic peroxycarboxylic acid.
The bleaching result obtainable depends on the nature and reactivity of the peroxycarboxylic acid formed, on the structure of the bond that is to be perhydrolyzed and on the solubility of the bleach activator in water. A large number of substances are known as bleach activators according to the prior art. These are usually reactive organic compounds having an O-acyl or N-acyl group which, promoted by the residual moisture present, react even in the washing powder mixture with the bleaching agent, such as, for example, sodium perborate, if both components are present unprotected.
To prevent reaction with the bleaching agent and hydrolysis in the presence of alkaline constituents of the detergent, and to ensure sufficient storage stability, the bleach activator is employed in the detergent and cleaner preparations in granulated and coated form.
Numerous auxiliaries and processes have been described in the past for granulating these substances. EP-A-0 037 026 describes a process for producing readily soluble activator granules comprising between 90 and 98% by weight of activator. For this purpose, the pulverulent bleach activator is homogeneously mixed with likewise pulverulent cellulose ethers or starch ethers and then sprayed with water or an aqueous solution of the cellulose ether or starch ether, simultaneously granulated and then dried. Since starch and cellulose derivatives only form a gelatinous mass with water, the flowability and adhesion properties of which are insufficient, the activator granules prepared by the process described in EP-A-0 037 026 only have moderate strength.
According to EP-A-0 070 474, it is possible to prepare similar granules by spray-drying aqueous suspensions comprising the activator and the cellulose or starch ether. However, this does not result in a better strength of the granules. EP-A-0 374 867 describes another process for preparing activator granules, where the activator is initially moistened with water and subsequently mixed with the pulverulent auxiliary, preferably sodium carboxymethylcellulose, and granulated. This process variant achieves better coating of the activator particles with the auxiliary, resulting in better storage stability. However, it does not improve the strength of the granules.
EP-A-0 240 057 and EP-A-0 241 962 describe the use of readily water-soluble film-forming polymers as binders in activator granules. Other constituents of the granules described are salts and, if appropriate, bentonite. The granules described are very brittle and display little abrasion resistance.
The use of polymers which are poorly water-soluble at pH 7 and only readily water-soluble at pH 10 as binders in activator granules, if appropriate in combination with cellulose ethers or starch ethers, is described in EP-A-0 468 824. In this process, the polymer is employed as aqueous dispersion and not as a solution. The resulting disadvantage is a worse distribution of the polymer in the granules, associated with a poorer binding of the activator particles and correspondingly with a reduced strength of the granules.
Activator granules containing organic binders, for example carboxymethylcellulose, and a disintegrant are described in EP-A-0 238 341. The content of disintegrant does not improve the strength of the granules. At elevated atmospheric humidity it is observed that the granules even disintegrate more easily.
Thus, all the granules and granulation processes described have the disadvantage of a poor abrasion resistance of the activator granules. Since the storage stability of activator granules in detergents and cleaners decreases significantly with an increasing proportion of fines, a poorer abrasion resistance, during/handling, normal manner naturally results in a poorer storage stability.
The object of the present invention was to improve the abrasion resistance and storage stability of activator granules.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that the abrasion resistance and storage stability of granules comprising bleach activators and binders can be improved significantly by addition of about 1 to 5% by weight of readily water-soluble film-forming, optionally acidic polymers.
The invention provides bleach activator granules, obtained by mixing one or more bleach activators with one or more binders and x% by weight of the total amount of one or more water-soluble polymers, spraying of water which comprises 100-x% by weight of the total amount of the water-soluble polymer, where x is a number from 0 to 100, and subsequent granulation and drying.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The granules according to the invention are based on customary and known bleach activators, for example from the group consisting of the activated carboxylic esters, carboxylic anhydrides, lactones, acylals, oxamides, N-acylated amines, amides, lactams, acyloxybenzenesulfonates, acylated sugars, and also nitriles or nitrites which carry a quaternary ammonium group, for example N,N,N′,N′-tetraacetylethylenediamine (TAED), glucose pentaacetate (GPA), xylose tetraacetate (TAX), sodium 4-benzoyloxybenzenesulfonate (SBOBS), sodium trimethylhexanoyloxybenzenesulfonate (STHOBS), tetraacetylglucoluril (TAGU), tetraacetylcyanic acid (TACA), di-N-acetyldimethylglyoxime (ADMG) and 1-phenyl-3-acetylhydantoin (PAH). The granules according to the invention may comprise one or more of these bleach activators.
The amount of bleach activator, based on the finished dry granules, is from 50 to 99, preferably from 70 to 98, in particular from 80 to 95%, by weight.
Suitable binders are cellulose and starch and their ethers or esters, for example carboxymethylcellulose (CMC), methylcellulose (MC) or hydroxyethylcellulose (HEC), and the corresponding starch derivatives or mixtures thereof. The amount of binder, likewise based on the finished granules, can be from 1 to 45, preferably from 3 to 10%, by weight.
The two pulverulent components bleach activator and binder can be mixed in customary mixing devices operating batch-wise or continuously, which are generally fitted with rotating mixing implements, for example in a ploughshare mixer. Depending on the effectiveness of the mixing device, the mixing times for a homogeneous mixture are generally between 30 seconds and 5 minutes.
This mixture is subsequently moistened with an aqueous solution of one or more polymers at temperatures of from about 20 to 80° C. Polymers which are suitable for this purpose are all types of organic polymers insofar as they are water-soluble. Particularly suitable polymers are polyacrylic acid, polymaleic acid or fully copolymers of acrylic acid and maleic acid in partially or completely neutralized form. The amount of water-soluble polymer and its concentration in the aqueous solution is adjusted such that the proportion of the polymer in the finished granules is approximately from 0.1 to 10, preferably from 0.5 to 7, in particular from 1 to 5%, by weight and the water content of the mixture during granulation is approximately from 10 to 30, preferably from 15 to 20%, by weight.
This mixture is then granulated, preferably in the same aggregate which has previously been used to mix the components.
The water content of the resulting granules is subsequently reduced to below 2, preferably below 1%, by weight. The excess water can be removed by drying with input of heat, where the temperature of the granules advantageously does not exceed 100° C. and is below the melting point of the bleach acti
Cramer Jurgen
Himmrich Johannes
Clariant GmbH
Dearth Miles B.
Gupta Yogendra
Hanf Scott E.
Petruncio John M.
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