GB2073768A - Washing Bar - Google Patents

Abstract

Washing bars for cleaning fabrics and washing bars for personal washing are disclosed. The improved bars of the invention, which comprise at least about 10% by weight of a detersive surfactant with or without a detergency builder, less than about 20% by weight of water and optionally about 50% by weight of an inert filler and yeild a pH of at least 6 when dispersed in one part by weight of water, include a material yielding halite ions in aqueous media, preferably sodium chlorite. The bars when used for washing under ultra-violet radiation conditions, e.g. from an artificial satisfactory bleaching to articles washed therewith.

Description

SPECIFICATION Washing Bar The invention relates to a washing bar, i.e. a detergent composition in bar form.

It is known to include bleaches in cleaning products, in particular in detergent compositions for cleaning fabrics and hard surfaces, for example. It is known for these bleaches to be photobleaches or to be bleaches activated by photosensitive bleach activators. For example, United States Patent Specification No. 4,033,81 8 describes a detergent composition containing particular species of zinc phthalocyanine as an oxygen bleach activator.

It is also known to use alkali metal chiorites as a bleach. For example, it is known to bleach cellulose with sodium chlorite in an acid medium, the chlorite in the acid medium producing chlorine dioxide, which is the species responsible for the actual bleaching. Acidic media are generally unsuitable for domestic cleaning processes. It is also known to activate chiorites at high pH with activators such as hydroxylammonium salts (see US Patent Specification No. 3,836,475), but such activators are expensive and may also be toxic. For these reasons they have not found commercial success in domestic situations.

It is further known from British Patent Specification No. 1,397,595 to use alkalimetal chlorite, particularly sodium chlorite, activated by high energy radiation, particular from X-rays, y-rays and electron rays, for bleaching fabrics under alkaline conditions.

It is an object of the present invention to provide a detergent composition in bar form which imparts a bleaching effect at alkaline or neutral pH without the use of high cost activators or high energy X-rays, y-rays or electrons rays.

We have discovered that satisfactory washing and bleaching of fabrics can be obtained by using a washing bar containing a chlorite or other halite, if the liquor containing the formulation or fabrics in contact therewith are irradiated with ultraviolet light. The present invention therefore provides a detergent composition in bar form for washing under ultra-violet light radiation.

Thus, according to the invention there is provided a detergent composition in bar form comprising: (i) at least about 10%, preferably from about 15% to about 99.5% by weight of a detersive surfactant with or without a detergency builder; (ii) at least about 0.1%, preferably from about 0.5% to about 40% by weight of a material yielding halite ions in aqueous media; (iii) less than about 20% by weight of water; and optionally (iv) up to about 50% by weight of an inert filler, the composition yielding a pH of at least 6.0 when dispersed in one part by weight of water.

The detersive surfactant may be selected from soaps; anionic, zwitterionic, amphoteric, semipolar, nonionic or cationic surfactants; and any mixtures thereof. Suitable such surfactants are for example sodium soaps of C,2C,8 fatty acids, sodium alkyl benzene sulphates, sodium alkane sulphonates, sodium olefin sulphonates, sodium alkyl sulphates and ethylene oxide or ethylene oxide/propylene oxide condensation products.

Further suitable surfactant materials are disclosed in Schwartz-Perry: "Surface-active agents and detergents", Vol. 11, 1958. In laundry bars for cleaning fabrics the detersive surfactant may include a detergency builder in an amount of up to about 80%, preferably about 15% to about 40% by weight of the composition. The builder may be selected from alkali metal phosphates and carbonates, aluminosilicates and other known inorganic and organic builders. Examples of such builders are sodium tripolyphosphate, sodium pyrophosphate, sodium orthophosphate, sodium carbonate, zeolite and nitrilotriacetate. A particularly preferred composition contains a synthetic anionic surfactant and a detergency builder.

The material yielding halite ions in aqueous media is preferably selected from chlorites and bromites, particularly chlorites, of substituted or unsubstituted ammonium, alkali metals (for example sodium, potassium or lithium) or alkaline earth metals (for example calcium or magnesium). The preferred material is sodium chlorite.

The inert filler, when present, may be selected from sodium sulphate, calcite and clays and mixtures thereof.

It is usual for the bar to be rubbed onto fabrics which have already been wetted, after which the fabrics are agitated in water. The amount of water present depends to a large extent on the user.

Generally more than one part by weight of water will be present for each part by weight of the composition. For a laundry bar it is essential that the composition should yield a pH of at least 6.0, preferably from about 8.5 to about 11.0, when dispersed in one part by weight of water The desired pH may be achieved by the addition of buffering agents, although where the various components of the composition have a suitable natural pH, no buffering agent needs to be added.

The exposure to ultra-violet light may be achieved by exposing the dispersed composition of the fabrics in contact therewith to daylight or to an artificial source of ultra-violet light. Thus the dispersed composition may be irradiated before contact with the fabrics or while the dispersed composition is in contact with the fabrics, or alternatively the fabrics may be irradiated while in contact with the dispersed composition or thereafter. It is essential that this radiation should occur before the halite is removed, e.g. by rinsing, from the fabrics. The ultra-violet light preferably has a component with a wavelength of between about 200 nm and about 400 nm, most preferably less than 370 nm.The intensity of the ultra-violet light, as measured at the fabric surface or at the surface of the liquor is preferably from about 0.01 to about 10.0, more preferably from about 0.05 to about 0.2 Wm-2nm-l.

Typical bright sunlight has an intensity over most wavelengths of 0.1-0.2 Wmnm-l. Under these conditions a suitable exposure time is between about 10 minutes and about 10 hours, more preferably between about 30 minutes and about 4 hours, depending on the concentration of the chlorite in the liquor and on the degree of bleaching required. The preferred light intensity can alternatively be expressed as from about 1 0-1 to about 10-6, preferably from about 10-2 to about 10-4 Einsteins of energy in the 200 nm to 370 nm wavelength region per litre of liquor.

The detergent composition may contain one or more ingredients other than those specified above, for example other bleaches, bleach precursors and colorants, including photoactivated bleaches such as sulphonated zinc phthalocyanine, anti-foaming agents, anti-redeposition agents, perfumes, perfume carriers, enzymes, organic solvents, optical brightening agents, thickeners, preservatives, dyes, plasticizers, processing aids, whitening agents, colouring agents or electrolytes.

Preferred optical brightening agents for use in the present invention are disodium-4,4'-bis(2 sulphostyryl)biphenyl and disodium-4,4'-bis(4-phenyl-1 ,2,3-triazol-2-yl)-2,2'-stilbene-disulphonate.

The composition should, before use, contain substantially no material which in the aqueous liquor will react with and remove the halite ions. Thus, chlorite ions are known to react with chlorite or chlorine producing materials such as calcium hypochlorite or sodium dichloroisocyanurate to produce chlorine dioxide. Thus, the composition preferably contains, for each part by weight of halite-yielding material, less than 0.4 parts, advantageously less than 0.1 part by weight of a material which in aqueous media in the absence of UV-light reacts to a substantial extent with the halite ions, that is reacts with at least a major proportion of the haiite ions.

In order to achieve adequate soil removal from the substrate, in addition to bleaching, it is desirable for the ratio of the total weight of the surfactant and builder (when present) to the weight of the haiite yielding material to be in excess of 1 :1, preferably in excess of 3.5:1, ideally in excess of 5.0:1.

The invention can also be applied to give an improved personal washing bar for washing the skin.

In such bars the detersive surfactants will normally be soap, but may also be selected from synthetic anionic, zwitterionic, amphoteric, semi-polar, cationic and nonionic surfactants and mixtures thereof or mixtures thereof with soap, though generally without the inclusion of a detergent builder.

In use with the composition of the personal washing bar comes into contact with the skin in the presence of water. Simultaneously with, or subsequent to, the contact between the composition and the skin, the skin is exposed to ultra-violet light. While this may be derived from an artificial source, it is most convenient if the source of radiation is daylight.

There are no specific requirements in the methods used to prepare the bars of the invention. A number of methods are known in the art (see e.g. U.S. Patent Specifications No. 3,291,744 and 3,1 78,370) and these methods are suitable for the manufacture of bars with the material yielding halite ions being added at a suitable stage.

The invention will now be illustrated by the following non-limiting Examples, in which percentages and parts are by weight unless otherwise specified.

In the following Examples 1 and 2, a pyrex cell was partially filled with water. Heavily tea-stained cloths were soaked with water, rubbed with the surfactant bar being tested and then immersed in the water in the cell, with a cloth:liquor ratio of 1:4 and an effective liquor concentration of 20 g/l. The cell was then placed in the chamber of an Atlas Weatherometer which had been adjusted to an output to simulate solar radiation both in intensity and energy distribution. The chamber had an initial temperature of about 220C. After irradiating the cloths from one side only for a selected time, the reflectance of the treated cloths changes (AR460*), both of those regions of the cloths which are immersed in the liquor and of those regions of the cloths which were suspended above the liquor.

Reflectanct changes of both front and back of each cloth were measured, and the average taken.

The totally immersed cloth simulates a method of bowl-washing fabrics in daylight, whereas the suspended cloth simulates a re-wet sun-bleaching operation.

Example 1 Non-soap detergent test bars were used having the following approximate formulations: Ingredient % % /0 % Sodium alkyl benzene sulphonate 28 28 28 28 Sodium pyrophosphate 1 6 1 6 1 6 1 6 Sodium carbonate 10 10 10 10 Calcite 32 27 22 17 Sodium carboxymethyl cellulose 2 2 2 2 Sodium sulphate 6 6 6 6 Water 6 6 6 6 Sodium chlorite 0 5 10 15 The bars were prepared in the following manner: In a Planetex high shear mixer alkyl benzene sulphonic acid was neutralized with excess sodium carbonate. After about 5 minutes water; calcite; sodium carboxymethyl cellulose+sodium chlorite, sodium pyrophosphate+remaining water, were added and mixed in the given sequential order at approximately 5 minutes' intervals.

The mass was then milled twice in a 3-roller mill, followed by plodding and cutting into bars.

The results are set out in the following Table I.

Table I AR460*

Chlorite Irradiation Suspended Immersed Concentration time cloth cloth 0 1 hour 0.1 0.0 0 1.5 hours 3.0 1.5 0 2 hours 3.3 4.1 5% 1 hour 3.7 1.7 5% 1.5 hours 6.4 3.2 5% 2 hours 7.8 6.3 10% 1 hour 5.4 5.1 10% 1.5 hours 11.4 10.4 10% 2hours 12.2 14.7 15% 1 hour 5.6 6.7 15% 1.5 hours 11.4 13.5 15% 2 hours 12.0 18.5 Example 2 Example 1 was repeated using non-soap detergent test bars of the following approximate formulations: Ingredient /0 % % % Sodium alkylbenzene sulphate 20 20 20 20 Sodium tripolyphosphate 30 30 30 30 Sodium orthophosphate 3 3 3 3 Sodium carboxymethyl cellulose 2 2 2 2 Water 9 9 9 9 Calcite 29 24 19 14 Sodium chlorite 0 5 10 15 Sodium carbonate 7 7 7 7 The bars were prepared by mixing the ingredients in the following order:: In a Planetex high shear mixer sodium carbonate and sodium tripolyphosphate were mixed with alkyl benzene sulphonic acid and a small amount of water for 1 5 minutes to neutralize the alkyl benzene sulphonic acid to sodium alkyl benzene sulphonate. Thereafter the calcite; sodium carboxy methyl cellulose+sodium chlorite+sodium orthophosphate; and water were added and mixed in the given sequential order at approximately 5 minutes' intervals.

The mass was then milled and plodded to form bars in the manner as described in Example 1.

The results are set out in the following Table II.

Table II AR460*

Suspended Immersed Chlorite % Treatment time cloth cloth 0 1 hour -2.0 -2.1 0 1.5 hours 1.4 -2.9 0 2 hours 5.4 -2.0 5 1 hour 6.8 1.4 5 1.5 hours 7.4 1.6 5 2 hours 19.8 9.7 10 1 hour 7.3 3.6 10 1.5 hours 13.0 9.7 10 - 2 hours 8.5 9.7 15 1 hour 12.2 17.2 15 1.5 hours 14.5 45.6 15 2 hours 21.3 38.0 I ne ueurrrlenl iiquias containing sodium chlorite in the above Examples had a pH of between 8.5 and 11.0.

Examples 3 to 5 The following compositions were made into personal washing bars and were found to exhibit a refreshing effect when used for skin washing in daylight.

Example 3 Ingredient Sodium soap of tallow fatty acid 45.26 Sodium soap of coconut fatty acid 37.04 Coconut fatty acid 4.50 Sodium chlorite 1.00 Butylated hydroxy toluene G.13 Phosphoric acid 0.12 Titanium dioxide 0.24 Water and minor ingredients balance Example 4 Ingredient Sodium acyl isethionate 48.6 Sodium dodecyl benzene sulphonate 2.0 Sodium soap of coconut fatty acid 11.0 Coconut fatty acid 3.0 Sodium chlorite 0.5 Stearic acid 21.7 Water and minor ingredients balance Example 5 Ingredient % Sodium C11-C14 alkane sulphonate 22.1 Sodium C15-C18 alkane sulphonate 29.4 Sodium C16-C18 olefin sulphonate 22.1 Myristyl alcohol 6.3 Cetyl alcohol 5.0 Stearyl alcohol 5.0 Sodium chlorite 2.0 Water and minor ingredients balance

Claims (7)

Claims

1. A detergent composition in bar form comprising: i) at least 10% by weight of a detersive surfactant selected from the group consisting of soaps, anionic, cationic, zwitterionic, semi-polar, amphoteric and nonionic surfactants and mixtures thereof, with or without a detergent builder; ii) at least 0.1% by weight of a material yielding halite ions in aqueous media, selected from the group consisting of chlorites and bromites of alkali metals, alkaline earth metals and substituted or unsubstituted ammonium: iii) less than about 20% by weight of water; and optionally iv) up to about 50% by weight of an inert filler, the composition yielding a pH of at least 6 when dispersed in one part by weight of water.

2. A composition according to Claim 1 wherein the surfactant is a synthetic anionic surfactant and the composition contains a detergency builder.

3. A composition according to Claim 1, wherein the material yielding halite ions in aqueous media is sodium chlorite.

4. A composition according to Claim 1 or 2, wherein the amount of detersive surfactant with or without a detergency builder is from 15% to 99.5% by weight of the composition.

5. A composition according to Claim 1 or 3, wherein the amount of material yielding halite ions in aqueous media is from 0.5% to 40% by wight of the composition.

6. A composition according to any one of Claims 1 to 5, wherein the composition, before use, contains, for each part by weight of the material yielding halite ions in aqueous media, less than about 0.4 parts by weight of a material which, in aqueous media in the absence of ultra-violet light reacts to a substantial extent with the halite ions.

7. A composition according to any of Claims 1 to 6, wherein the ratio of surfactant plus builders, when present, to the material yielding halite ions is at least about 3.5:1.