US3459669A - Bleaching compositions for hard surfaces - Google Patents

Description

United States Patent 3,459,669 BLEACHING COMPOSITIONS FOR HARD SURFACES Balaram Das, Rotterdam, and Karel Gerhard van Senden, Schiedam, Netherlands, assignors to Lever Brothers Company, New York, N.Y., a corporation of Maine No Drawing. Filed July 18, 1966, Ser. No. 565,748 Claims priority, application Great Britain, July 20, 1965, 30,814/ 65 Int. Cl. 011d 7/18 US. Cl. 252-99 10 Claims ABSTRACT OF THE DISCLOSURE Powdered bleaching compositions for hard surfaces, particularly scouring powder bleaching compositions, containing an inorganic per compound, such as an inorganic perborate, have their bleaching power improved by the incorporation therein of an activator mixture consisting of urea and an alkali metal phosphate.

The invention relates to low temperature bleaching compositions for hard surfaces containing inorganic per compounds, and to a process for the preparation of such bleaching compositions. In particular the invention relates to scouring powder compositions containing inorganic per compounds such as perborates with an effective bleaching action at relatively low temperatures of eg 10-50 C., as well as at higher temperatures.

Known low temperature bleaching compositions, including scouring powder bleaching compositions, generally contain a chlorine releasing compound, such as dichlorocyanuric or trichlorocyanuric acid, which has the disadvantage of spreading a disagreeable chlorine smell which persists for some time after use, especially on the skin. Another disadvantage connected with compositions based on chlorine bleaches is their instability in storage, resulting in a decrease of the bleaching effect. These disadvantages are not present to the same extent in bleaching compositions based on inorganic per compounds such as perborates. However, inorganic per compounds are relatively inactive bleaching agents at low temperatures of e.g. 10-50 C. Their bleaching effect increases with increasing temperatures and attains its maximum at the boil.

Certain heavy metal ions, e.g. Co are known to catalyse the bleaching action of inorganic per compounds and hence catalysts comprising these heavy metals have been suggested for incorporation in low temperature bleaching compositions containing inorganic per compounds, e.g. sodium perborate. There are, however, some disadvantages connected with such metal ion catalysts, especially cobalt catalysts. Many of these metal ions, e.g. Co tend to irritate the skin which makes them unsuitable for use in compositions that come into contact with the skin. Another disadvantage of such catalysts is that in order to obtain a stable product in a suitable form for incorporation in a composition, they have to be prepared in a rather complex and specific manner which results in the catalysts being expensive. Besides, in the case of coloured ions, they tend to give the characteristic colour of the metal ion to the object bleached. It has been suggested to overcome this nuisance by the addition of certain chelating or complexing agents.

It has now surprisingly been found that highly effective powdered bleaching compositions, particularly scouring powders containing inorganic per compounds, can be obtained with comparable bleaching action to chlorinecontaining bleach compositions without the use of such heavy metal ion catalysts and consequently without the above disadvantages, by the addition of an activator mixture consisting of urea and an alkali metal phosphate. The bleaching compositions according to the invention which are in the form of substantially dry powdered materials, are stable when stored at room temperature and may be packaged in suitable containers.

The compositions can be advantageously used for cleaning and stain-removing of various types of surfaces, viz. tile surfaces, porcelain objects, sinks, metal surfaces, etc. In the cleaning of metal surfaces they also effectively remove rust stains.

Either urea or the phosphates alone have hardly any effect on the bleaching action of per compounds, and it is quite surprising that mixtures of both compounds have at least the same catalysing effect on inorganic per compounds as the metal ion catalysts.

The phosphates which can be suitably mixed with urea according to the invention could be any condensed phosphate, such as the alkali metal hexametaphosphates, pyrophosphates, tripolyphosphates, or an alkali metal orthoor metaphosphate, such as Na HPO Na PO Naand/or K-hexametaphosphate being most particularly suitable.

The weight ratio of urea to alkali metal phosphate in the composition may be varied throughout a considerable range, but generally lies between 5:1 and 1:5, a ratio of approximately 1:1 giving the best results.

There are no particular requirements with respect to the ratio of activator mixture to per compound. Preferably, however, 'aweight ratio of at least 1:10 should be maintained in order to obtain the proper and desirable effect.

The bleaching or scouring powder compositions may contain 120% of each of phosphate and urea, preferably 35% and 130% inorganic per compounds, preferably 5-20%. In addition they may also contain so-ealled fillers e.g. sodiumor aluminum sulphate, as well as alkaline building materials e.g. sodium silicate, sodium carbonate etc. Scouring powder compositions contain additional amounts of abrasive material, such as silica, feldspar, calcium carbonate and the like.

The composition according to the invention can be prepared by intimately mixing the substantially dry components in any conventional mixing apparatus. Preferably a proper amount of surface-active agent is added in order to give them an effective washing effect as well. In some instances other ingredients may be required, such as perfumes, germicidal substances, etc. These ingredients can be properly added in the last stages of the mixing operation.

The invention will now be illustrated by the following examples:

Example 1 Two scouring powder compositions were prepared containing sodium perborate, one of them with phosphate and urea. Table 1 gives the compositions.

the bleaching of tea stains on unglazed tiles by applying them with water as a paste on the tile surface. The following test method was used:

The reflectance of a tea-stained tile was measured. Ten grams powder were mixed with 7 ml. distilled water and stirred for 30 seconds. The mixture was powdered on the tile surface. After a contact time of l or 2 minutes the TABLE 2 Increase in reflectance (percent) after contact time of- Composition 1 min. 2 min I 23 32 II 3 11 It can be seen from Table 2 that increase of reflectance with composition I which contains sodium hexametaphosphate and urea is much more than that with composition 11 without hexametaphosphate and urea.

Example 2 Two scouring powder compositions containing sodium perborate were prepared, one only with sodium hexametaphosphate and the other only with urea.

In Table 3 the two compositions are given.

The compositions were again tested at room temperature for the bleaching of tea stains on unglazed tiles in the same way as described in Example 1.

In the folowing Table 4 the increases in reflectance of the tiles after treatment are given.

TABLE 4 Increase in reflectance, (percent) after contact time oi- Compositlon 1 min. 2 min.

III IV 4 8 It will be seen that compositions III and IV are not much better than composition 11 of Example 1.

Example 3 The following compositions mentioned in Table 5 were tested in the same way as described in the previous examples, and the results are given in Table 6.

TABLE 5 Parts by weight TABLE 6 Increase in reflectance (percent) after contact time of- Composition 1 min. 2 min.

V 24 30 VI 27 33 From the above examples it will be seen that compositions I, V and VI, according to the invention are much better than compositions II, III and What is claimed is:

1. A powdered bleaching composition for hard surfaces consisting essentially of an inorganic perborate and an effective amount of an activator mixture for catalyzing the bleaching action of the inorganic perborate, the activator mixture consisting of urea and an alkali metal phosphate, the weight ratio of urea to alkali metal phosphate being between 5:1 and 1:5.

2. The powdered bleaching composition defined by claim 1 wherein the weight ratio of urea to alkali metal phosphate is about 1:1.

3. The powdered bleaching composition defined by claim 1 wherein the weight ratio of activator mixture to inorganic perborate is at least 1:10.

4. The powdered bleaching composition defined by claim 1 wherein the alkali metal phosphate is an alkali metal monohydric phosphate.

5. The powdered bleaching composition defined by claim 1 wherein the inorganic perborate is sodium perborate.

6. The powdered bleaching composition defined by claim 1 wherein the alkali metal phosphate is an alkali metal condensed phosphate.

7. The powered bleaching composition defined by claim 6 wherein the alkali metal condensed phosphate is an alkali metal hexametaphosphate.

8. The powdered bleaching composition defined by claim 6 wherein the alkali metal condensed phosphate is an alkali metal tripolyphosphate.

9. A powdered bleaching composition for hard surfaces consisting essentially of from about 1% to about 30% by weight of an inorganic perborate from about 1% to about 20% by weight of urea and from about 1% to about 20% by weight of an alkali metal phosphate.

10. The powdered bleaching composition defined by claim 9 wherein the amount of inorganic perborate is from about 5% to about 20% by weight, the amount of urea is from about 3% to about 5% by weight and the amount of alkali metal phosphate is from about 3% to about 5% by weight.

References Cited UNITED STATES PATENTS MAYER WEINBLATI, Primary Examiner US. Cl. X.R, 81113252-186