Process for decreasing the build up of inorganic incrustations on textiles and detergent composition used in such a process

Description

[0001] The present invention relates to a process for decreasing the build-up of inorganic incrustations on fabrics caused by water hardness and repeated washing cycles with detergent compositions.

[0002] More particularly, the present invention relates to a process for decreasing the build-up of inorganic incrustations wherein a co-builder is added to the washing cycle, and to detergent and/or anti-incrustation compositions containing said co-builder.

[0003] It is well known that detergents contain builders in order to support detergent action and to eliminate calcium and magnesium ions (hardness ions), which arise partly from the water and sometimes also from soil and fabrics.

[0004] In case of multiple washing cycles the washing performance is significantly reduced because of the build up of inorganic incrustations on fabrics and on washing machine components. Such build up of inorganic incrustations on fabrics decreases the flexibility of fibres and consequently shortens the fabric life, in addition to greying the tissue.

[0005] A well known builder is sodium tripolyphosphate which has excellent properties in the washing process even at low concentrations. Despite its many advantageous properties however, it causes serious ecological problems, namely eutrophication of stationary or slowly flowing surface waters leading to extreme algal growth which adversely influences marine organisms. As a result, the use of phosphate free detergents is of great importance.

[0006] Some substitutes of phosphate builders such as zeolites have been adopted. However, zeolites alone in water softening have poor efficiency. Therefore, good anti-incrustation effects are achieved only in the presence of auxiliary compounds called co-builders.

[0007] The most widely used co-builders are synthetic polymers and/or co-polymers of olefinic mono- or dicarboxylic acids such as acrylic and maleic acid and copolymers of said monomers with other allylic or vinylic monomers. A common characteristic of these polymeric materials is their minimal biodegradability which leads to ecological problems.

[0008] There are known other non-polymeric co-builders, such as EDTA (ethylenediaminetetraacetic acid sodium salt), NTA (nitrilotriacetic acid sodium salt) and phosphonates. As with the polymeric co-builders these substances too are non-biodegradable.

[0009] It is therefore an object of the present invention to provide a process for decreasing the build-up of inorganic incrustations on fabrics and on washing machine components by using co-builders which are very efficient in reducing incrustation build up during washing cycles and which are cheap and biodegradable.

[0010] Another object of the present invention is to provide detergent and/or anti-incrustation compositions containing said biodegrable co-builders.

[0011] It has now surprisingly been found that certain carbohydrates show a high efficiency in reducing incrustation build up when combined with detergents, particularly with zeolite-based detergents.

[0012] In European patent application 0 618 286 there is described a co-builder based upon a non-reducing carbohydrate or a non-reducing carbohydrate derivative. Preferred among the non-reducing carbohydrate derivatives are certain sugar alcohols exemplified by maltitol and, especially, by mannitol. It has now been found however that the carbohydrate or carbohydrate derivative need not be fully non-reducing but that some reducing activity is tolerable and that certain compounds showing such activity are as effective co-builders as the sugar alcohols referred to above.

[0013] In accordance with one aspect of the present invention therefore there is provided a process for decreasing the build-up of inorganic incrustations on fabrics and on washing machine components during multiple washing cycles with detergent compositions characterized by the addition to the washing cycle of a co-builder based on a carbohydrate or carbohydrate derivative having a DE of 0.5 to 20 inclusive.

[0014] A range of carbohydrates or carbohydrate derivatives having a DE of 0.5 to 20 inclusive may be used in the process of the invention eg. polydextrose or partially degraded inulin but preferably the carbohydrate or carbohydrate derivative is a maltodextrin having a DE of 0.5 to 20 inclusive, particularly a DE of 8 to 17 inclusive.

[0015] "DE" or dextrose equivalent is a measure of the reducing activity of a carbohydrate measured by comparison with dextrose which has a DE of 100.

[0016] The co-builders based on such carbohydrates and carbohydrate derivatives having a DE of 0.5 to 20 inclusive can be incorporated into the detergent compositions or added as such directly to the washing bath.

[0017] In accordance with another aspect of the present invention, there are provided detergent and/or anti-incrustation compositions containing the hereinbefore defined co-builders. These compositions may also contain other conventional components such as anionic, non-ionic, cationic or amphoteric surfactants, alkali metal salts (e.g. sodium carbonate, sodium silicate), neutral salts (e.g. sodium sulphate), zeolites, bleaching agents, bleaching activators and other minor ingredients.

[0018] In accordance with one preferred embodiment of the present invention the novel co-builders are used in combination with zeolite-based detergents.

[0019] The co-builders used according to the present invention are particularly efficacious in the presence of inorganic persalts, such as sodium perborate tetrahydrate or monohydrate.

[0020] The amount of the co-builders used in the process can vary from 1 g/washing cycle to 40 g/washing cycle, and preferably from 2 g/washing cycle to 20 g/washing cycle. This amount is achieved by a range of from 0.5 % to 20 % and preferably by a range of from 1 % to 10 %, expressed as 100 % dry substance of co-builder in the detergent or anti-incrustation compositions.

[0021] The co-builders used according to the present invention are naturally derived, biodegradable compounds. In combination with detergents they reduce the build up of inorganic incrustations on fabrics and on washing machine components. Such activity is more significant at high temperatures e.g. at 90°C.

[0022] The present invention is disclosed in still further detail in the following Example, which is supplied for purely illustrative and not limiting purposes.

Example

[0023] The co-builder activities of the following compositions were evaluated on a laboratory scale using the so-called "Hampshire" test which measures the Ca⁺⁺ sequestering capacity of the composition. The test was carried out as follows :-
1 gram of the substance under test is dissolved in 100 ml of demineralised water, the solution filtered and the filtrate made up to 100 ml with demineralised water. 10 ml of a 2 % by weight aqueous solution of sodium carbonate is then added, the pH adjusted to 11 with sodium hydroxide solution (0.1 N or more concentrated for a large pH adjustment) and the temperature regulated at 20°C. The solution is then titrated with a calcium acetate solution (39.59 g/l) at a rate of 1 ml/min until a permanent turbidity becomes apparent. The quantity of Ca⁺⁺ in the calcium acetate solution, determined by a preliminary titration with EDTA, is 10.03 mg Ca⁺⁺/ml.

[0024] The results of the determinations in mg Ca⁺⁺/g of test substance were as follows : -

Substance	Solution with borax (2g/50 ml)	Solution without borax
Maltodextrin (DE = 12)	40.7	9.7
Mannitol	46.9	7.9
Maltitol	47.8	9.2

Claims

1. A process for decreasing the build up of inorganic incrustations on fabrics and on washing machine components during multiple washing cycles characterized by the addition to the washing cycle of a co-builder based on a carbohydrate or carbohydrate derivative having a DE of 0.5 to 20 inclusive.

2. The process according to Claim 1, characterized in that the carbohydrate or carbohydrate derivative is a maltodextrin.

3. The process according to Claim 2 characterized in that the maltodextrin has a DE of 8 to 17 inclusive.

4. The process according to Claim 1, characterized in that the co-builder as such is added directly to the washing bath.

5. The process according to Claim 4, characterized in that the co-builder is added in amount ranging from 1 g/washing cycle to 40 g/washing cycle, preferably from 2 g/washing cycle to 20 g/washing cycle.

6. The process according to Claim 1, characterized in that the co-builder is incorporated in the detergent composition.

7. Detergent and/or anti-incrustation composition containing a co-builder based on a carbohydrate or carbohydrate derivative having a DE of 0.5 to 20.

8. Detergent and/or anti-incrustation composition according to Claim 7, characterized in that it contains a zeolite.

9. Detergent and/or anti-incrustation composition according to Claim 7, characterized in that it contains the co-builder in an amount ranging from 0.5 % to 20 %, preferably from 1 % to 10 %, expressed as 100 % dry substance of the detergent or anti-incrustation composition.

10. Detergent and/or anti-incrustation composition according to Claim 7, characterized in that it contains an inorganic persalt.