GB2127426A - Detergent bars - Google Patents

Abstract

Detergent bars comprising from 5-60% by weight of detergent active material, 0-60% by weight of detergent builder material and acid treated bentonite clay have improved physical hardness.

Description

SPECIFICATION Detergent bars This invention relates to improved detergent bars.

Detergent bars used, for example, for fabric washing and cleaning surfaces require certain porperties. In some climatic conditions or when specific components are used the bar may be soft after manufacture or become soft during use. When in this condition the bar may lose its appeal to the public and sufferfrom an increased rate of wea r.

The invention is an improvement in detergent bars containing from about 5% to about 60% by weight of detergent active material and from zero to about 60% by weight of detergent builder material. Detergent bars ofthistype are characterised by containing an effective amount of an acid-treated bentonite clay.

The treated claywill be effective to harden the bar to a more acceptable level when judged by the user or by a more acceptable rate of wear. The effective amount of treated bentonite will usually be above about 1 % by weight of the total bar and up to about 20% by weight. Preferably the level will be above about 2% and upto about 10% by weight.

The acid treated bentonite is prepared from naturally occuring bentonite clays; these have an essentially montmorillonite structure. Preferablythe bentonite hasaswelling number, determined by the British Pharmacopoeia method, of at least 20. The raw clay is treated with dilute, for example 10% to 20% by weight, sulphuric acid or othersuitable mineral acid.

Usually the acid solution will be used in the range 1:2 to 2:1 by weight relative to the clay. The mixture is refluxed as a slurry for a period, usually Sto 12 hours, filtered and the clay washed free of acid. It is then dried, suitably atabout 11O"Cfor3to 4 hours,to a moisture content of about 10% to about 15%: the yield is a bout 70%. Acid-treated bentonite, which is obtainable commercially, has a partially disrupted crystalline structure and is capable of acting as a very efficient absorbentforwater. The structure of the bentonite during acidtreatment is monitored by X-ray powder diffraction.The spacing between the layers in the crystalline structure (C-axis) give rise to a distinctive line in the X-ray spectrum and a suitable acid treated bentonite will retain the C-axis line.

In a typical process bentonite (500 g) with a swelling number of 35was refluxed as a slurry in sulphuric acid (4N, 2.5 litres). The product (330g) had a bulkdensity of 0.76 gimp, a superficial acidity of 0.07%, a water absorption capacity of 100% and a water vapour absorption capacity of 13%.The infra-red spectrum showed a well defined band at 360 cm- which corresponds to the presence of structural hydroxyl groups; it is believed these groups assist in providing the product with its desirable water absorption properties.

The detergent active and builder components usable in the detergent bars of the invention are well characterised in the field ofdetergentbartechnology.

Examples of these components will be found in "Surface Active Agents" by Schwartz & Perry published by Interscience (1949) and Volume II by Schwartz Perry & Berch (Interscience 1958). The actives are present in the general classes of anionic, nonionic, amphotericand cationic materials; in general there will be no criticality in the selection of active or builder materials. Examples of active materials are fatty acid ester sulphonates, alkane sulphonates, alcohol sulphates, alkaryl sulphonates, fatty acid sulphonates, ethoxylated alcohols, alkyl sulphates, alkene sulphonates and soaps.

Specific examples of builder materials are: water soluble phosphate salts, e.g. sodium tripolyphosphate, pyrophosphate and orthophosphate; water soluble carbonate salts, e.g. sodium carbonate; organic builders, e.g. sodium nitrilotriacetate, sodium tartarate, trisodiu m carboxymethyl oxysuc ci nate, sodium oxydisuccinate and sulphonated fatty acids of specific chain length.

Other ingredients,forexample, sodium alkaline silicates, starch, sodium carboxy methyl cellulose, colouring materials, fluorescers, opacifiers, germicides, perfumes, fillers, abrasives and bleaching agents, are optionally added.

The bar softness was studied using a Tomson and Mercer Cone penetrometer. The printed end ofthe cone penetrates the bar and the extent of penetration is measured on the scale attached to the instrument.

Thus the highervalues of the penetration reading are obtained from the softer bars. The measurments provide a quantitative comparison, although on an arbitraryscale.

From experience it has been found a penetration value of 10 or below is characteristic of a commercially satisfactory product Examples: Detergent bars of the invention will now be described to illustrate but not limitthe invention.

Example! Atest detergentformulation (2kg batch) suitable for processing into bar form was prepared. Linear alkyl (C12) benzene sulphonic acid (41 6g) was placed in a Sigma mixer and sodium carbonate (1409) and sodium hydroxide (1049 asa50%wjwsolution) added with mixing: the latterwas added dropwise.

The temperature during mixing was maintained in the range400to450C.Thefollowing components were then added in sequence with a mixing period of five minutes between each addition - calcite (809), sodium tripolyphosphate (6009), trisodium orthophosphate (2409 anhydrous), wax (409), dical cium phosphate (2009), sodium carboxymethyl cellu lose (409), fluorescer (69) and titanium dioxide (6g).

The acid-treated bentonite (2009) and a mixture of water (449) with colour and perfume were then added in sequence with five minute mixing periods. Follow ing a final mixing period often minutes the dough was milled and plodded into barform. These bars formed sample A.

Example II Sample B ofthe test bars was prepared using the procedure of Example I but omitting the dicalcium phosphate ingredient and utilising 2809 ofcalcite.

Sample C, which acted as a control, was prepared using the procedure of Example I but omitting the acid-treated bentonite and utilising 2809 of calcite.

The three bar samples were tested bythe penetra tion method immediately after manufacture and after periods of time. The results are given in Table I.

Table I Time (hrs) 0 0.5 1 24 SampleA 33 21 16 2 Sample B 31 18 12 3 SampleC 39 29 NM ca 29 NM indicates no measurement was made These results demonstrate the presence of acidtreated bentonite (10% level) provides bar products ofthe desired hardness.

Example 111 The advantage of using acid treated bentonite compared with non treated bentonite was studied using the following composition. Sample D contained acid treated bentonite as the bentonite component, while Sample E incorporated untreated bentonite.

The samples (each of 2 kg) had the composition: % wt Sodium linear alkyl (Cq2) benzene sulphonate 20 Sodium tripolyphosphate 30 Sodium carbonate 7 Trisodium orthophosphate (anhydrous) 3 Wax 2 Dicalcium phosphate 10 Calcite 4 Sodium carboxymethyl cellulose 2 Bentonitecomponent 10 Titanium dioxide present Fluorescer/colour present Perfume present Organicandinorganicsalts ca 2 Moisture 8.5 The appropriate detergent sulphonic acid was neutralised with sodium carbonate in a Sigma mixer with caustic soda (50% w/wsolution) being added dropwise. Thetemperature was maintained in the range 400 to 450C during mixing.The following components were then added in sequence with a mixing period offive minutes between each addition -trisodium orthophosphate and wax; calcite and dicalcium phosphate; sodium tripolyphosphate; sodium carboxymethyl cellulose, titanium dioxide andfluorescer; bentonitecomponentwith some water; perfume and colour.

After a final mixing period often minutes the dough was milled and plodded into bar form. The samples were tested using the penetrometer method described previously; the results are given in Table II.

Table II Time (hours) 0 0.5 1 24 SampleD 17 13 12 6 Sample E 38 26 13 10 These results demonstrate the acid treated bento nite provides harder bars than the use of non treated bentonite, although the latter bars are commercially acceptable. Sample D bars had bettercolourthan Sample E.

Claims (7)

1. A detergent bar comprising from 5% to 60% by weight of detergent active material and from zero to 60% by weight of detergent builder material and containing an effective amount of an acid treated bentonite clay.

2. A detergent bar as claimed in Claim 1 containing at least 1 % by weight of acid treated bentonite.

3. A detergent bar as claimed in Claim 1 or 2 containing up to 20% acid treated bentonite.

4. A detergent bar as claimed in Claim 2 containing above 2% of acid treated bentonite.

5. A detergent bar as claimed in any preceding claim containing upto 10% of acid treated bentonite.

6. A detergent bar as claimed in any preceding claim wherein the acid treated bentonite was obtained from bentonite which has a swelling number of at least 20.

7. A detergent bar substantially as described with reference to Samples A, B and D of the Examples.