NO166655B - APPLICATION OF PEROXYCARBOXYLIC ACID SUSPENSIONS AS Pale Blends. - Google Patents

Abstract

The disclosure relates to the use as pourable bleaching compositions of aqueous suspensions of peroxycarboxylic acids, said suspensions also containing an alkali metal salt of an alkyl benzene sulphonic acid. The compositions are chemically and physically stable. Their physical stability can be enhanced by the addition of sodium sulphate or potassium sulphate. They are protected from hazards due to spilling and drying up. Also disclosed are the above bleaching compositions in the packaged form.

Description

The present invention relates to the use as a pourable, aqueous bleaching mixture in the pre-bleaching treatment of soiled laundry at low temperatures of a mixture which comprises as a bleaching component a diperoxycarboxylic acid with 8-13 carbon atoms in an amount which gives an active oxygen content of 0.1-4%, water, optionally 0.1-1% by weight of a separating agent and an optional thickening agent of cellulose type where the bleaching mixture further comprises an alkali metal salt of an alkylbenzenesulfonic acid where the alkyl residue contains 9-22 carbon atoms in an amount of 0.5-15% by weight and 0.01-20 % by weight sodium sulphate, potassium sulphate or a mixture of sodium and potassium sulphate, which quantities are calculated on the basis of the weight of the mixture.

British Patent No. 1,535,804 describes liquid bleaching compositions having a viscosity of from 200 to 100,000 mPa.s and containing a peroxide, a thickener and water. They are suitable for use in washing machines and automatic clothes dryers.

The advantage of using liquid bleaching mixtures over

solid bleaching mixtures is that in their production there is no need for cost-increasing forming steps such as drying and granulation, and the substances to be treated are bleached quickly and evenly, so that high concentrations of the bleaching agent on

places can be satisfactorily avoided.

The bleaching agents in British patent 1,535,804, insofar as they can be poured (see below), have the disadvantage that they are not physically stable, which after prolonged storage leads to phase-separated products with a thick bottom layer that is difficult to disperse or homogenize, and as a result of this, the advantage of uniform distribution over the substance to be partially cleaned disappears.

The present bleaching mixture does not show this disadvantage.

The invention relates to the use of the above-mentioned type, in which the bleaching mixture also comprises an alkali metal salt of an alkylbenzene sulphonic acid.

A further advantage of the present bleaching composition is that, provided the proportions of the ingredients to be used are chosen correctly, it is protected against hazards due to spillage and drying, which lead to the formation of solid peroxide particles. Peroxides in solid form are known to cause an explosion, and are dangerous in the event of impact and abrasion.

However, in the case of spilling and drying of properly selected present suspensions, solid peroxide particles will be formed which have such a coating that they are desensitized. The pourable mixtures described in British patent 1,535,804

are not protected in this way, the amount of thickener required for these mixtures being so small that in the event of spillage and drying up, solids are formed which are insufficiently desensitized. From experiments, it has further been found that this disadvantage cannot be avoided by adding well-known desensitizing agents such as sodium sulphate to these suspensions, because the properties of these will then deteriorate further.

It should be noted that the present suspensions containing a peroxycarboxylic acid and an alkali metal salt of an alkylenebenzenesulfonic acid are disclosed in US Patent 4,126,573. However, this patent relates to solid, granular bleaching mixtures and the present suspensions are only used for the preparation of these solid mixtures by drying, which is obvious in light of what is mentioned in the introduction to US patent 4,126,573 (column 1, lines 17-20) , namely that the liquid-form bleaching mixtures containing peroxide materials as active bleaching agent tend to reduce the bleaching effect over longer storage times.

In light of US patent 4,126,573, the application of

the present suspensions as bleaching mixtures are not close at all. Because, if the peroxycarboxylic acid is finely divided in the water, the probability of decomposition during storage is high. Furthermore, it has been found from experiments that such cleavage occurs in the case of a number of anionic and nonionic emulsifiers. However, it has been found that the presence of an alkali metal salt of an alkylbenzenesulfonic acid as an emulsifier has no or hardly any detrimental effect on the active oxygen content of the mixture.

The mixture used according to the present invention is physically stable, i.e. after storage for 6 weeks at 20°C, the peroxycarboxylic acid is well dispersed and the suspension does not show any phase separation. If precipitation occurs at all, the homogeneity of the dispersion can be easily restored by shaking it gently.

Furthermore, the mixture used according to the invention is chemically stable, etc. that after storage for 2 weeks at 40°C it still has the same or practically the same active oxygen content.

The mixture is pourable, which means that at 20°C the mixture has a viscosity between 1 and 1200 mPa.s, preferably between 50 and 500 mPa.s (Brookfield rotary viscometer [RV type], 20 rpm)

The invention also relates to the use of such bleaching mixtures which are new as such.

The bleaching component in the present mixture consists of a peroxycarboxylic acid which originates from a dicarboxylic acid containing 8-13 carbon atoms. Such peroxycarboxylic acids are not, or hardly soluble, in water (solubility less than 1% by weight in water at 20°C). Mixtures of these acids can also be used.

It is preferred that the present composition contains diperoxydicarboxylic acids such as 1,12-diperoxydodecanedicarboxylic acid, 1,13-diperoxytridecanedicarboxylic acid or suitable mixtures thereof.

The production of these acids is carried out in a known manner by reacting the corresponding dicarboxylic acids with hydrogen peroxide in the presence of sulfuric acid.

In general, the mixture contains peroxycarboxylic acids

in such an amount that the active oxygen content in the mixture is between 0.1 and 4%, preferably between 0.1 and 3%.

The present mixture must contain an alkali metal salt of an alkylbenzenesulfonic acid. The alkyl group can be branched or straight-chain and contain 9-22 carbon atoms, preferably 9-15 carbon atoms, especially 11-13 carbon atoms. As examples of these alkylbenzenesulfonates, sodium undecylbenzenesulfonate, sodium dodecylbenzenesulfonate and sodium tridecylbenzenesulfonate can be mentioned. Mixtures of these sulphonates can also be used.

It is preferred that the mixture used according to the invention contains sodium dodecylbenzene sulphonate.

It is preferred that the mixture according to the invention contains sodium umdodecylbenzene sulphonate.

The alkali metal salt of an alkylbenzenesulfonic acid should be used

in such an amount that the mixture can be poured and is physically stable. In general, the mixture will contain the alkali metal salt of an alkylbenzenesulfonic acid in an amount of 0.5 to 15% by weight,

and preferably 2 to 10% by weight, calculated on the weight of the mixture. Use of amounts less than 0.5% by weight will result in mixtures

with insufficient physical stability; the use of amounts greater than 15% by weight will result in viscous mixtures that can no longer be poured.

The alkali metal salts of alkylbenzenesulphonic acids which are normally used in practice as an emulsifier are so-called technical products, in which an inorganic salt such as sodium sulphate is present as an impurity. Although these technical products can very well be used to prepare the present mixtures, a preferred embodiment consists in that also

special inorganic salts are added. It has been found that adding sodium sulphate, potassium sulphate or mixtures thereof has a beneficial effect on the physical stability of the mixtures, i.e. if there is found to be any precipitation at all after the use of a technical emulsifier alone, it can be completely stopped by further use of the inorganic salts. It has also been found that by using the inorganic salts, mixtures with the same properties can be prepared,

which contains less emulsifier than when these inorganic salts are not used. The latter embodiment is preferred in practice, due to the significantly lower cost price for the inorganic salts compared to the emulsifying agent used. A preferred inorganic salt is sodium sulfate.

The amount of inorganic salt to be used will partly depend on the amount of inorganic salt originating from the emulsifier as a contaminant and should be such that the bleach mixture can be poured and is physically stable. In general, the bleaching mixture used according to the invention will contain organic salt including the inorganic salt originating from the emulsifier in an amount of 0.01 to 20% by weight, preferably 2

to 10 weight*, calculated on the weight of the mixture.

The mixture used according to the invention may also contain other additives, and as examples of these can be mentioned: - thickeners; examples of such are described in British patent 1,535,804. Thickeners can be used in such

maximum amounts that the mixture remains pourable;

- insulating agents, which serve to bind any metal ions present that can accelerate the decomposition of peroxides. Examples of insulating agents are ethylenediamine tetraacetate, sodium pyrophosphate, phosphoric acid, dipicolinic acid and hydroxyethylidene diphosphonic acid. They can be used in quantities from

0.01 to 1% by weight, calculated in relation to the weight of the mixture;

- building materials such as polycarboxylates, and finally

optical brighteners, perfume and organic solvents.

The present bleaching mixtures can be used very effectively in the pre-bleaching treatment of dirty laundry at a low temperature (e.g. approx. 30°C). In the treatment of dirty laundry with the commonly used strong and weak detergents, they can also be suitable to be added separately to the washing water. Their effect is at least equivalent to the bleaching compositions described in British patent 1,535,804.

The mixtures used according to the invention can be prepared by adding the peroxycarboxylic acid while stirring to an acidified mixture (preferably pH 3.5-4.5) of water, alkylbenzene sulphonate and other additives. The peroxycarboxylic acid can be used in the form of powder (primary particle size l-100<y>) or in the form of wet filter cake which is obtained after peroxycarboxylic acid precipitation from the corresponding dicarboxylic acid and hydrogen peroxide. If necessary, the pH of the mixture is set to a particular desired value, which should lie in the acidic range when using e.g. aqueous sodium hydroxide or hydrochloric acid. It is preferred that the pH is not higher than 5. Higher values would have a detrimental effect on the chemical stability of the mixture. A lower pH

than 2 should also be avoided, however. Because, due to dilution with water, the resulting insufficiently high final pH would cause metal parts in the washing machine used to corrode. Particularly preferred are mixtures with a pH of 3.5-4.5, especially 3.9-4.1.

The invention shall be further described in the following examples. All percentages are % by weight.

Example 1

Mixtures as mentioned in Table 1 were prepared. Mixtures 1-6 are according to the invention. The pH values for these mixtures were in the range from 3.5 to 4.5. Mixture 7 is according to British patent 1,535,804.

A sample of each mixture was stored to determine its chemical stability. After 2 weeks at 40°C, all samples had retained their active oxygen content.

Furthermore, a sample of each mixture was stored in order to determine the physical stability. After 6 weeks at 20°C, mixtures 1, 2, 4, 5 and 6 did not show any phase separation or precipitation phenomenon. Although the sample in mixture 3 had precipitation, no thick bottom layer had formed, and the original homogeneity of the dispersion could be restored by gentle shaking. But the sample of mixture 7 had precipitation and a thick bottom layer had formed (phase separation) which could not be re-dispersed well.

In order to measure the differences in protection against dangers

arising from spillage and drying between the compositions of the invention on the one hand and the composition of British Patent 1,535,804 on the other, samples of compositions 2, 3 and 7 were evaporated to dryness by means of an air stream at 25 to 30°C , after which the material thus obtained was subjected to a pressure-boiler test. This sample is described in Vervoer Gevaarlijke stoffen, 23 December 1980, Aanhangsel Al

bij annex A, pp. 907, 908, 915: Staatsuitgeverij. In this test, 10 g of the material to be examined is heated with a standardized gas flame in a pressure cooker equipped with a rupture disk set at 6 bar. In the side wall of the pressure boiler is an exhaust opening with a variable diameter.

The test method means that such an exhaust opening

are found which after splitting (explosion, combustion) of the peroxide give a still intact rupture disc. The smaller the permissible opening, the more secure the formulation. The permissible opening

(in. mm) is given as PVT value. The PVT values found for the material from mix 2 were less than 1 mm, from mix 3 less than 1 mm and from mix 7 it was 6 mm. (The PVT value for pure diperoxydodecanedicarboxylic acid is 7 mm).

Example 2

In this example, the effect of various anionic and nonionic emulsifying agents on the chemical stability of peroxycarboxylic acid suspensions is given.

Suspensions were prepared from diperoxydodecanedicarboxylic acid (11.65 g wet filter cake with an active oxygen content of 5.1%), hydroxyethylidene diphosphonic acid ("Dequest"

2010; 0.25 g), emulsifier and water, and the PH of the suspensions was 3.9 to 4.1.

The nature and quantity of the emulsifiers and the amounts of water are indicated in the table below. Data on the chemical stability of the suspensions, i.e. the active oxygen content of the suspensions after storage at 40°C is mentioned in the lower part of the table.

The results in the table show that the emulsifiers, apart from alkylbenzene sulphonate, have a detrimental effect on the chemical stability of the peroxycarboxylic acid-containing suspensions.

It should be added that suspension 1 is not a mixture used according to the invention; it contains approx. 30% emulsifier and has a viscosity of 1975 mPa.s. It has been found that the effect of the emulsifiers on the chemical stability of the peroxycarboxylic acid mixtures can be very well established when they are used in relatively high concentrations.

Claims (8)

1. Use as a pourable, aqueous bleaching mixture in the pre-bleaching treatment of soiled laundry at low temperatures of a mixture that comprises as a bleaching component a diperoxycarboxylic acid with 8-13 carbon atoms in an amount that gives a active oxygen content of 0.1-4%, water, optionally 0.1-1% by weight of a separating agent and an optional thickening agent of cellulose type where the bleaching mixture further comprises an alkali metal salt of an alkylbenzenesulfonic acid where the alkyl residue contains 9-22 carbon atoms in an amount of 0 .5-15% by weight and 0.01-20% by weight of sodium sulfate, potassium sulfate or a mixture of sodium and potassium sulfate, which amounts are calculated on the basis of the weight of the mixture. 2. Use according to claim 1 where the alkyl group in the alkali metal salt of an alkylbenzenesulfonic acid contains 9-15 carbon atoms. 3. Use according to claim 1, where the alkali metal salt of an alkylbenzenesulfonic acid is sodium dodecylbenzenesulfonate. 4. Use according to claim 1 where the diperoxycarboxylic acid is selected from 1,12-diperoxydodecanedicarboxylic acid and 1,13-diperoxytridecanedicarboxylic acid. 5. Use as a pourable, aqueous bleaching mixture that is separately added to a washing liquid that is also added to a detergent mixture of a mixture that comprises as bleaching component a diperoxycarboxylic acid with 8-13 carbon atoms in an amount that gives an active oxygen content of 0.1-4 %, water, optionally 0.01-1% by weight of a separating agent and an optional thickening agent of the cellulose type, in which the bleaching mixture further comprises an alkali metal salt of an alkylbenzenesulfonic acid where the alkyl residue is 9-22 carbon atoms in an amount of 0.5-15% by weight and 0.01-20% by weight sodium sulphate, potassium sulphate or a mixture of sodium and potassium sulphate, which amounts are calculated on the basis of the mixture's weight. 6. Use according to claim 5 in which the alkali metal salt of an alkylbenzenesulfonic acid is sodium dodecylbenzenesulfonate. 7. Use according to claim 5 in which the alkyl group in the alkali metal salt of an alkylbenzenesulfonic acid contains 9-15 carbon atoms. 8. Use according to claim 5 in which the diperoxycarboxylic acid is selected from 1,12-diperoxydodecanedicarboxylic acid and 1,13-diperoxy tridecanedicarboxylic acid.