GB2256647A - Detergent composition - Google Patents

Abstract

Method of making a detergent product in bar form containing a detergent active, detergency builder and other ingredients. The method comprises pro-mixing starch with the acid form of at least some of the detergent active prior to at least partial neutralisation thereof with silicate.

Description

DETERGENT COMPOSITION This invention relates to non-soap detergent laundry bars, used in certain countries for fabric washing and for cleaning surfaces. Such bars contain detergent active and detergent builder materials together with fillers and usually other components.

Such bars require an acceptable physical strength so that they retain their structural integrity during handling, transport and use. The hardness of the bars, at the time of manufacture and subsequently, is an especially important property. Techniques are known for enhancing the hardness of bars, generally consisting of including certain ingredients at a prescribed stage in manufacture, and bars so manufactured are known as structured bars.

Structured bars are commercially available. These bars generally have a density much higher than that of laundry bars made from ordinary soap. Because of the higher density, the Size of the bar for a given weight of material is considerably smaller than that of a soap laundry bar and the bar is thus less attractive to the consumer, more difficult to handle during fabric washing and can have a gritty feel.

In GB 1 230 427 (Colgate-Palmolive) it is suggested that at least 22% by weight of starch and/or cereal flour may be added to certain laundry bar compositions in order to reduce the density thereof. Some of the laundry bars disclosed in this prior art document are structured by addition of sodium silicate. In all cases the silicate is added when the mixture is alkaline to avoid formation of silica.

We have now devised an alternative route for forming low density, structured bars by addition of ingredients during manufacture in a particular order.

The invention provides a method of making detergent laundry bars containing anionic detergent active, detergency builder and other ingredients, in which method a plurality of components including the detergent active and builder are mixed together and the mixture is formed into bars, characterised by pre-mixing starch with the acid form of at least some detergent active prior to at least partial neutralisation thereof with silicate.

In a second aspect this invention provides a detergent laundry bar produced by the above method. This is advantageous in that processing is simplified and a silica structured grit free bar may be obtained. It is also advantageous in that it is possible to achieve high levels of detergent active and high water content which enables use of detergent actives in slurry or paste form.

Although this invention achieves bar structuring by use of in situ silica generation, it is preferred to incorporate as an additional structurant a two component system of a polyvalent metal compound and a silaceous material. In this case the silaceous material may be silica itself in finely divided form or silicates (alkaline or neutral), polymeric silicates and amorphous sodium aluminosilictes and kaloin, talc-pyrophyllite and smectite. The polyvalent metal compound may be an aluminium salt.

It is also preferable to increase bar structuring by incorporating a water soluble metal phosphate into the mixture preferably by mixing with the acid form of the detergent active prior to neutralisation. Such incorporation of phosphate can provide an acceleration or enhancement of bar structuring.

Detergent active and builder components are well characterised in detergent bar technology. These components are described in "Surface Active Agents" by Schwartz and Perry (Interscience 1958).

Specific examples of anionic detergent actives useful in this invention are: linear and branched alkyl benzene sulphonates, alkane sulphonates, secondary alcohol sulphates, primary alcohol sulphates, alpha oleo in sulphonates, alkyl ether sulphates, fatty acyl ester sulphonates, and mixtures of these. The invention is particularly applicable when at least part of the detergent active is alkyl benzene sulphonate, or a mixture thereof with fatty acyl ester sulphonate or primary alcohol sulphate.

Generally the amount nf detergent active (reckoned as anhydrous) will be from 5 to 65 wt % of the total bar composition, preferably 10 to 45 or 55 wt %, based on the total composition. Preferably the amount of detergent active present before the hardening materials are added is such as to provide at least 5 wt % of the final bar composition.

Some detergent active from a category other than anionic, such as nonionic, amphoteric or zwitterionic may be included within these quantities. Preferably then the preparation of anionic detergent active is such as to provide at least 5 wt %, better at least 10 wt % of the total bar composition.

One group of detergency builders are water soluble phosphate, e.g. sodium tripolyphosphate, pyrophosphate, orthophosphate, and metaphosphates (also called glassy phosphates). Phosphates intended to act as builder, rather than to function in bar structuring in accordance with this invention can be added after both neutralisation and the addition of structuring materials.

Part of any phosphate added as structuring material prior to the alkaline silicate and/or additional silaceous material and/or polyvalent metal compound may also function as a detergency builder. Indeed the amount may be chosen so as to provide a surplus to function as builder.

Examples of other builders are water soluble carbonates, e.g. sodium carbonate used in excess of the quantity required for neutralisation; organic builders, e.g.

sodium nitrilotriacetate, sodium tartrate, sodium citrate, trisodium carboxymethyl oxysuccinate, sodium oxydisuccinate, sodium -u'p'.;onated long-chain monocarboxylic acids, polymeric carboxylate builders such as polyacrylic acid, maleic acid copolymers and oxidised starch and cellulose; and aluminosilicate ion exchangers; e.g. zeolite 4A.

The water soluble phosphate which is preferably added as one of the structuring materials may be orthophosphate, pyrophosphate, tripolyphosphate, glassy phosphate or other phosphate condensates. A description of the various phosphate condensates is given in "Phosphorus and its compounds" by J.van Waser. Any water soluble salt can be used, but sodium salts will generally be used, as the most readily available and cost effective. A mixture of phosphates may be used.

A preferred amount of this phosphate used as one of the structuring materials is from 1 to 35% reckoned as anhydrous phosphate by weight of the final bar composition, more preferably 3 to 20%.

Generally the total amount of detergency builder plus any phosphate functioning as a structuring material (both reckoned as anhydrous) lies in the range from 5 to 60 wt % preferably 8 to 45 wt % of the total bar compositions.

When phosphate is added before the alkaline silicate and/or additional silaceous material and/or polyvalent metal compound, the amount so added is preferably at least 1 wt % of the total bar composition.

The silicate is preferably an alkali metal silicate and preferably of the type with a molar ratio of SiO2:M2O of less than 4, more preferably less than 3, most preferably between 3 and 1. M is preferably sodium.

Preferably the amount of alkali metal silicate added to the mixture to effect partial neutralisation is from 1 to 15%. The preferred amount of total silaceous material is such as to introduce from 1 to 10% of silica into the bar compositions and more preferably 2 to 5% reckoned as anhydrous silica by weight of final bar formulation.

The starch used in the mixture is preferably corn starch but other starches such as yucca starch, potato or tapioca starch may be used. Preferably the amount of starch in the final bar by weight is below 25%, and more preferably below 20% and above 2%. Most preferably the amount of starch in the final bar composition is between 10 and 20% by weight.

The polyvalent metal compounds may contain various metals.

Specific possibilities are aluminium which may for instance be introduced as aluminium sulphate, other salts with aluminium as cation or as sodium aluminate, magnesium which may be used as its sulphate or other salt with magnesium as cation and boron which may be introduced as boric acid or as a neutralised salt. Other group IIa, group IIb, transition or lanthanide metal salts can be used but are not preferred.

A preferred amount of this polyvalent metal compound is from cm. 5 to 12% reckoned as anhydrous material by weight of the final bar composition, more preferably from 2 to 10%.

Built NSD bars often contain a proportion of filler which although generally chemically inert is significant in contributing to the properties of the bar. An appropriate range for such filler (if used) is 5 to 60% by weight of the composition. The filler may consist of water soluble salts such as sodium sulphate but possibly it includes water-insoluble filler. The filler present may even be water insoluble and accordingly the possible amount of water insoluble filler is 5 to 602. Examples of water insoluble fillers are calcite, aluminosilicate, dolomite, feldspar, calcium silicate and calcium sulphate (and also clays such as talc, kaolin and bentonite if these are not complexed in accordance with preferred embodiments of this invention).

Other ingredients may also be present in the composition.

These include sodium carboxymethyl cellulose and cellulose ethers, cellulose itself, lather enhancing agents such as long chain alkanolamides and alcohols exemplified by coconut alcohol, humectants such as glycerol, sorbitol and mono- and disaccharides, colouring materials, enzymes, fluorescers, opacifiers, germicides, desiccants such as calcium, magnesium and aluminium oxides, perfumes and bleaching agents. Alkanolamines may be included, as described in our UK published patent application 2184452A.

A built detergent bar in accordance with this invention will generally be substantially rigid, enabling it to be rubbed against an item of laundry.

To prepare bars according to this invention, it is preferred to begin with the acid form of the detergent active, admix phosphate (if any is added before neutralisation) then starch and then part neutralise with alkaline silicate, then in succession mix in any other ingredients such as soda ash and filler(s), any remaining phosphate and finally minor ingredients such as perfume.

Mixing can be carried out in a high shear mixer and be followed by conventional extrusion and bar stamping.

In some instances, part of the starch is added prior to neutralisation of the acid form of the detergent active and the remainder added with the ingredients such as the soda ash and filler(s).

Total neutralisation is preferably effected by the known procedure of dry neutralisation, in which a carbonate (usually soda ash) is added to the acidic mixture.

Neutralisation in other ways, such as with very concentrated sodium hydroxide solution or a mixture of sodium hydroxide and soda ash, is also possible.

The invention will be further explained and illustrated by means of the following examples, in which all proportions and percentages are by weight unless otherwise stated.

In these examples, bars with the compositions given were manufactured on a conventional plant for the manufacture of NSD bars. This plant consisted of a sigma mixer, mill and vacuum plodder. The bars were tested for bar hardness immediately after extrusion (while the bar was still hot), and after 24 hours.

The test was carried out by means of a penetometer. The penetrometer used was a PNR6 manufactured by SUR, Berlin.

Example 1 Bars of the following composition were manufactured according to a procedure in which mixing and neutralisation were all carried out in a sigma mixer.

Formulation A LAS1 21.3 STp2 16.7 Soda Ash 3.0 Starch 12.5 Silicate (anhydrous) 3 9.0 Aluminium sulphate (anhydrous) 3.0 Lime 1.0 China Clay 16.3 Minors 0.6 Moisture 16.6 3 Density g/cm 1.68 1. LAS denotes linear alkyl benzene sulphonate as analysed in the freshly prepared bar.

2. STP denotes sodium tripolyphosphate.

3. denotes alkaline silicate with an SiO2:Na2O ratio of 4. denotes moisture in the freshly prepared bar.

The components marked 'premix' in the table below were mixed for two minutes following which the LAS was fully neutralised by addition of the remaining ingredients from formulation A. In each sequence only half of the ^ available alkaline silicate was added te the premix Sequence I Sequence II Sequence III Starch Starch LAS Premix Soda Ash Alkaline Alkaline (for partial silicate silicate neutralisation) LAS LAS O hr penetration 3.5 3.5 4.0 mm 24 hr penetration 1.2 1.2 1.5 mm Grit? No Yes Yes The bars were assessed for surface feel by scrubbing to obtain a flat surface and rubbing 20 times on wet cotton.

The bar was then turned in the hand in 24"FH still water and the feel described as either gritty or not.

These results show that sequence I according to the invention gives rise to grit free, low density bars of acceptable hardness.

Example 2 Bars of the following composition were manufactured according to the procedure of Example 1.

Formulation A B LAS 21.3 21.4 STP 16.7 16.7 Soda Ash 3.0 3.0 Starch 12.5 12.5 Silicate (anhydrous) 9.0 - Aluminium sulphate 3.0 Lime 1.0 1.0 China Clay 16.3 28.3 Minors 0.6 0.6 Moisture 16.6 16.5 Density g/cm3 1.68 1.70 Ohr penetration (mm) 3.5 6.8 24hr penetration (mm) 1.2 3.5 Formulation A was prepared as in Sequence 1 of Example 1 according to the invention. Formulation B contains no silicate or aluminium sulphate and therefore no structuring by silica or aluminium silicate generation i situ is present. Comparison of the penetration data of formulation A against B shows the structuring advantage obtained by using silica and silicate structuring.

Example 3 Bars of the following compositions were manufactured according to the procedure of Example 1, Sequence 1 where applicable.

Formulation A C LAS 21.3 21.6 STP 16.7 20.8 Soda Ash 3.0 3.0 Starch 12.5 Silicate 9.0 4.5 Aluminium Sulphate 3.0 1.5 Lime 1.0 1.0 China Clay 16.3 16.7 Calcite - 20.9 Minors 0.6 0.6 Moisture 16.6 9.4 Density g/cm 1.68 1.82 These results show that the addition of starch allows lower density bars to be produced. These have the advantage that the size of the bar for a given weight is similar to that of a soap laundry bar and is thus attractive to the consumer.

Example 4 Bars of the following composition were manufactured according to the procedure of Example 1 except: i) in formulations E and F, part of the total starch content was added following neutralisation of the detergent active; and ii) for comparison purposes, in formulation D the total starch content was added following neutralisation of the detergent active with the ingredients such as the soda ash.

Formulation D E F G LAS 20.1 20.3 20.5 20.2 STP 12.5 12.5 12.5 12.5 Soda Ash 3.0 3.0 3.0 3.0 Starch* 0.0 5.0 10.0 20.0 Starch** 16.7 15.0 10.0 0.0 Silicate 8.5 8.5 8.5 8.5 Aluminium sulphate 3.0 3.0 3.0 3.0 Lime 1.0 1.0 1.0 1.0 China Clay 18.1 13.9 13.7 14.6 Minors 0.6 0.6 0.6 0.6 Moisture 16.5 17.2 17.2 16.6 Density. g/cc 1.68 1.62 1.64 1.63 Grit Yes No No No * starch added prior to LAS neutralisation ** starch added after LAS neutralisation The results show when at least part of the starch is added prior to neutralisation of the detergent active grit free bars are obtained.

Claims (10)

Claims

1. A method of making detergent laundry bars containing anionic detergent active, detergency builder and other ingredients, in which method a plurality of components, including the detergent active and builder are mixed together and the mixture is formed into bars, characterised by pre-mixing starch with the acid form of at least some detergent active prior to at least partial neutralisation thereof with silicate.

2. A method as claimed in claim 1 characterised in that substantially all the starch is pre-mixed with the acid form of at least some detergent active prior to at least partial neutralisation thereof with silicate.

3. A method as claimed in claim 1 characterised in that i) part of the starch is pre-mixed with the acid form of at least some detergent active prior to at least partial neutralisation thereof with silicate; and ii) the remaining starch is added after step (i).

4. A method as claimed in claim 1 characterised by the laundry bar containing from 5% to 65% by weight of the total bar composition of detergent active.

5. A method as claimed in claim 1 characterised by the laundry bar containing from 5% to 60% by weight of the total bar composition of detergency builder.

6. A method as claimed in claim 1 characterised by the at least partial neutralisation of the detergent active with an alkali metal silicate.

7. A method as claimed in claim 6 characterised by the at least partial neutralisation of the detergent active with an alkali metal silicate with a molar ratio of SiO2:M2O of less than 4.

8. A method as claimed in claim 1 characterised by mixing at least one component of a two-component structuring system with the acid form of at least some detergent active prior to neutralisation thereof and incorporating the other component of the system before or after neutralisation, the said two components being a polyvalent metal compound and a silaceous material.

9. A method as claimed in claim 1 characterised by mixing a water soluble metal phosphate with the acid form of at least some detergent active prior to neutralisation thereof.

10. A detergent laundry bar produced by a method as claimed in any of the preceding claims.