SE450835B - Dishwashing composition - Google Patents

Description

15 20 25 30 35 450 835 '"" fïTv ~ fnmm 2 is to contribute to wetting and emulsification, at the same time as it must have a defoaming effect against eg proteins.

The bleach normally consists of organic chlorine compounds, which act as oxidative bleach with the task of attacking deposits of, among other things, coffee, tea and fruit juice.

When the compound comes in contact with water, it emits chlorine, which in addition to its bleaching effect also cures. In most cases, chlorinated is disinfected isocyanuric acid or salts thereof as an organic chlorine compound, and chlorinated sodium isocyanurates have, mainly for economic reasons, found the widest area of use.

In addition to the above components, dishwasher detergents often also contain varying amounts of conventional additives, such as alkali metal carbonates and bicarbonates, alkali metal sulphate, aluminum silicate, sodium borate, dyes, perfumes, etc.

When using conventional dishwasher detergents, starchy dish residues, for example from spaghetti and potatoes, cause special problems. Namely, the acetal bond in starch is difficult to hydrolyze, and even under the strongly alkaline conditions prevailing during the machine washing process, the starch degradation is slow; One way to accelerate the hydrolysis of starch is to introduce starch-degrading enzymes, so-called amylases, into the dishwasher detergent composition. As a result, a rapid removal of starch-containing food residues is achieved even at a neutral pH. The amylase acts by hydrolyzing u-1,4-glycoside bonds in amylose and amylopectin, thereby breaking down starch into soluble dextrins and oligosaccharides.

A difficult problem with amylases is that they are easily degraded in alkaline ling, although more alkali-resistant enzymes have an environment in this context. A development has taken place recently, but it has still not been possible to produce amylases which work well with products with a high alkali content, such as silicates. Since a high pH is required in the dishwashing solution in order for fat and protein to be removed, this means that a compromise must be made between enzyme activity and alkali content. practice has shown that the upper practical limit of the metasilicate content in dishwasher detergents is about 20% by weight if a moderately maintained enzyme activity is desired. degradation of the dishwashing effect with respect to fat and protein.

Various ways of solving the above problems have been proposed. Among other things, attempts have been made to use a kind of two-component system, in which amylase is first dissolved in a fairly neutral dishwashing solution and thereby given the opportunity to break down the starch for the required time. In a second dish step, a basically conventional dishwasher detergent with a high alkali content is then added. However, the use of a two-component system means an increased time consumption for the dish cycle and other practical problems. It is an object of the present invention to obviate the above problems and to provide a machine dishwashing detergent composition which contains enzyme with retained activity while exhibiting normal alkali metal silicate content. it has surprisingly been found in the invention that this object can be achieved if the alkali metal silicate content of the composition is in the form of two-layer granules, the core of which consists of alkali metal silicate, preferably sodium metasilicate (anhydrous or hydrate), and whose outer shell consists of alkali metal triphosphate or phosphate.

The further features of the invention appear from the following claims.

Thus, it has been found in the invention that if an enzyme, preferably amylase, is combined with a dishwasher detergent based on the above-mentioned two-layer granule, the starch-degrading effect of the enzyme will remain even at very high alkali levels. This is very surprising in that the alkali content of the silicate should inactivate the enzyme. The alkali content of the silicate is available for normal hydrolysis reactions after the dissolution of the bilayer granule in the dishwashing solution, which occurs immediately when the granule is brought into contact with the dishwashing solution. There is as yet no satisfactory explanation for the phenomenon that the enzyme is not inactivated by the strongly alkaline dishwashing solution when using bilayer granules in accordance with the invention, but it appears that it is rather a prolonged contact with dry silicate in the dishwasher detergent which is damaged. for the enzyme than a short break in a highly alkaline dishwashing solution. www. . . -...., ... A ï-.nu-n ~ vv ---- ~ "It should be mentioned in this connection that it is formerly known to the Swedish Patent 7706216-4 (publication number 424 739) to produce a two-layer granule of the kind which According to this prior art, granules of silicate, usually sodium metasilicate (anhydrous or hydrate), are used, which granules suitably have a grain size of 0.05-1.5. mm, preferably 0.2-1.2 mm, and on top of these granules a coating of powdery, partially hydrated tripolyphosphate is applied. The grain size of the finished two-layer granules is generally 0.25-2.5 mm, preferably 0.4-2 These two-layer granules thus contain both silicate and phosphate, but the outer surface consists only of phosphate and is thus not markedly alkaline. For further details regarding these known two-layer granules, reference may be made to the above-mentioned Swedish patent and 7706216-4.

Because chlorine inactivates enzyme in a very short time, probably by oxidative cleavage of peptide bonds, enzymes such as amylase cannot be used in conjunction with chlorine-releasing substances, such as the oxidative chlorine bleaches normally included in dishwasher detergent compositions. Therefore, in order to avoid such inactivation of the enzyme, the present invention provides either that the bleach is omitted altogether or if it is included in the composition, that it be a hydrogen peroxide-based bleach.

Preferred hydrogen peroxide-based bleaches are perborates and percarbonates, such as sodium perborate and sodium percarbonate.

There are no special limitations on the other components of the dishwasher detergent composition, but these can be selected from conventionally used substances.

The content ranges of the components of the composition according to the invention are generally within the following limits: alkali metal silicate / alkali metal phosphate bilayer granules 40-99% by weight surfactant 1-4% by weight oxidative hydrogen peroxide based bleach 0-15% by weight enzyme 0.5-5% by weight aaaitive up to 100 weighted in In the bilayer granule, the weight ratio of silicate / phosphate can vary within wide limits. A practically preferred weight ratio is from 80:20 to 40:60 calculated on anhydrous components. It is also possible, and sometimes advantageous, not to include the entire amount of phosphate in the composition in the bilayer granule, but to add a part as a separate component. One condition, however, is that each silicate grain is covered by such a thick phosphate layer that the surface no longer becomes strongly alkaline. Furthermore, the entire silicate content of the composition need not be in the form of two-layer granules, but a part of the silicate may be in free form without the protective phosphate layer obtained from the granules. However, in order to avoid detrimental effects on the enzyme, the amount of silicate present in this way must not be too large, and more particularly, according to the invention, at least half of the silicate must be in the form of two-layer granules. The composition preferably contains 1-3% by weight of enzyme, which is normally present in the form of a granulated product.

In order that the invention may be better understood, an example is given below, which is intended only to illustrate the invention and not to limit it.

EXAMPLE 'Three different dishwasher detergents, A, B and C, were manufactured with the following composition (figures indicate percentage by weight):. ..¿..¿.¿¿ .. è EE tripolyphosphate 40 40 - É metasilicate 5 aq 56 20 - É k two-layer granule - - 96 k * sodium sulphate - 36 - iir * enzyme (amylase) defoaming surfactant ll 1 * consisting of 40 parts tripolyphosphate and 55-60 parts metasilicate 5 aq ** sodium sulphate is an inert filler. eg '*** Termamyl 605 from Novo Industri A5.

Detergent C was a dishwasher detergent in accordance with the present invention, while detergents A and B g were comparative compositions. k After 3 months of storage in normal dishwasher detergent packaging and at ambient temperature and humidity, dishwashing tests were performed. The dirt load in the tests consisted of a mixture of potato flour, oatmeal, spinach, eggs, tomato juice, milk, tea, fat and minced meat. after washing, the washing effect was assessed partly as a total effect and partly as an effect on starch. The total effect was assessed directly visually, while the remaining starch was assessed after treatment of the dishes with iodine solution.

The results are shown in the table below. The scale goes from 0 to 10, where 0 is completely clean and 10 very dirty. The dosage of the detergent was 3 g / l and the hardness of the dish water was 3 dh.

J 'U 450 835 7 A B total dirt 4 5 starch dirt 4 l l As can be seen, formulation A shows a rather poor effect on starch but a good effect in general. Formulation B gives a good dishwashing effect on starch but is rather poor in other respects.

Only formulation C has a good effect on all dirt. . ..- f- fi- g-. . .w-øæp. ä.

Claims (8)

10 15 20 25 30 35 450 835 .m .fl -... fwmup -qji PATENTKRAV Vf 1. A dishwasher detergent composition which, in addition to conventional additives, comprises alkali metal silicate, alkali metal phosphate, surfactant, and, optionally, a hydrogen peroxide-based bleaching agent, characterized in that the composition also contains an enzyme, and that at least half of the alkali metal silicate and at least a portion of the alkali metal phosphate are in the form of bilayer granules with a core of alkali metal silicate surrounded by an outer shell of alkali metal phosphate. Composition according to Claim 1, characterized in that the enzyme is amylase. claim 1 or 2, characterized in that the alkali metal weight ratio of the bilayer granules is from 3. A composition according to the claim that silicate: alkali metal phosphate 80:20 to 40:60. Composition according to any one of claims 1-3, characterized in that it, calculated on its total weight, contains 40-99% by weight of granules, 1-4% by weight of surfactant, 0-15% by weight of bleach, 0 , 5-5% by weight of enzyme and the rest additive. Composition according to any one of claims 1 to 4, characterized in that the alkali metal silicate is sodium silicate. Composition according to any one of claims 1-5, characterized in that the alkali metal phosphate is sodium tripolyphosphate. 7. A composition according to any one of claims 1-6, characterized in that the surfactant is a nonionic surfactant, preferably a block polymer of ethylene and propylene oxide. Composition according to any one of claims 1 to 7, characterized in that the additives consist of alkali metal carbonate, alkali metal bicarbonate, alkali metal sulphate, corrosion inhibitors, dyes, perfume, a or mixtures thereof.