EP0912691A1

EP0912691A1 - Concentrated alkaline isotropic detergent liquid with bleach

Info

Publication number: EP0912691A1
Application number: EP97924117A
Authority: EP
Inventors: Michael John Day
Original assignee: Warwick International Group Ltd
Current assignee: Warwick International Group Ltd
Priority date: 1996-05-28
Filing date: 1997-05-28
Publication date: 1999-05-06
Also published as: NO985541L; CN1219962A; PL330118A1; CZ385398A3; SK160298A3; AU2968897A; KR20000016075A; CA2252634A1; TR199802461T2; JP2001501646A; BG102957A; ID17256A; BR9709384A; IL126559A0; WO1997045518A1; NO985541D0; GB9611063D0; TW381119B

Abstract

A concentrated alkaline isotropic fabric washing liquid detergent composition comprising at least 23 % of surfactants and further comprising at least 0.2 % hydrogen peroxide bleach, the composition is substantially free from hydrotropes which cause the pH to reduce and impair the effectiveness of the composition. Also a concentrated alkaline isotropic fabric washing liquid detergent composition comprising at least 15 % by weight of surfactant further comprises at least 0.2 % by weight hydrogen peroxide bleach and an optical brightener and is also substantially free from hydrotropes. The compositions may be used as a main wash bleaching liquid or a pretreatment liquid and may be activated with a bleach activator.

Description

CONCENTRATED ALKALINE ISOTROPIC DETERGENT LIOUΪP WΠΉ BLEACH

This invention relates to concentrated alkaline isotropic fabric washing liquid detergents with hydrogen peroxide bleach.

Concenrrated alkaline isotropic fabnc washing liquid detergents xisualry contain a hydrotrope to allow a high suj-factaπt level to be used without die viscosity becoming too great Typical hydrotropes are sodium xylene su-phαnate, ethanol, and propylene grycoL Inlemational application PCT/GB96 00642 contains such compositiøDs comprising a nrixture of nonionic surfactant and anionic surfactant together with a hydrotrope and hydrogen peroxide characterised in that die composition comprises greater than 40% total surfactant when nonionic rich or greater than 20% total surfactant when anionic rich. A concentrated peroxide liquid is desirable because of the reduced transport and storage costs. A solution to the problem of how to formulate stable concentrated alkaline isotropic fabric washing liquid detergents with peroxide has ehided those skilled in the ait for many years.

Although there are many publications of concentrated alkaline isotropic fabric washing liquid detergent formulations containing a hydrotrope, there are very few indeed that disclose hydrotrope- free fbrmiilations. The closest prior art is probably the 15% anionic (secondary alkane suJphonate) and 3.75% nonionic (primary alcohol ethoxylate (7EO)) composition disclosed in WO96/01311. This formulation had a total surfactant level below 20%. Furthermore, this coπφosiricπi did not contain additional ingredients such as optical brightener, aπti-redeposition or anri-dye transfer agent which renders me composition unsuitable for use as a practical concentrated alkaline isotropic fabric washing liquid detergent with hydrogen peroxide bleach.

Thickened peroxide compositions are also known. These contain a thickening system to boost viscosity when only low levels of surfactant are present. GB 2255507 is typical and discloses a thk-kened peroxide-containing composition with less than 10% surfactant These comrpositions are not suitable for use as laundry detergents. They are thickened in order to give the desired result of a squeezable ∞mposition that does not nm when put on to a vertical surface. Such compositions do not contain a hydrotrope and always contain less than 10% total surfactant A skilled person would not use these thickened hydrotrope-free compositions as a starting point for the formulation of a new concentrated fabric washing detergent

We have now found that the presence of a hydrotrope has a large and very undesirable negative effect on the storage stability of αmceπtrated alkaline isotropic fabric washing liquid detergents, particularly we have found that this is a problem for compositions containing high levels of surfactant This is a problem for the formulation of concentrated liquid detergents because conventionally such detergents contain hydrotropes. In this specification concentrated means that the liquid in its undiluted state contains more than 15% and preferably at least 20% and most preferably at least 23% total a^*(rfactant Unless stated otherwise all percentages are on a w w basis.

According to the present iwention there is provided a concentrated alkaline isotropic fabric washing liquid detergent composition comprising a total surfactant level which includes at least 15% surfactants and further comprises at least 0.2% hydrogen peroxide bleach and an optical brightener, characterised in that the composition is substantially free from hydrotropes. It is preferred that die composition has no added -^*r drot-rope whatsoever. A small presence of up to 2.5% preferably less than 1.5%, and most preferably less than 0.5% of a material which may "function as a hydrotrope may be present perhaps as a result of one of e ingredients of die composition containing this material as a minor constituent or impurity. Such ingredients are advantageously avoided as they probably compromise the shelf life of the composition, however, for an otherwise very stable cc-nφositiøn me loss in perfbnnance due to a very small amount of material which may function as a hydrotrope may still leave an acceptable shelf life. Such compositions which are substantially free from material which may mnction as a hydrotrope are therefore within the scope of the present invention. The total surfactant level is preferably at least 20%, more preferably at least 23 %. Preferably die composition comprises anionic and nonionic surfactants.

Any optic^*al r_-rigl^*ύ'£nCTtJιat is An optical brightener that has good compatibility with peroxide bleach is Tinopal CBS-X a distyiyl biphenyl derivative ex Ciba Geigy. Stϋbene based fluorescers may also be used as the optical brightener.

According to a second aspect of die invention there is provided a concentrated alkaline isotropic fabric washing liquid detergent composition comprising a total surfactant level which includes at least 23% of surfactants selected fiom the group corαprising anionic and nonionic surfactants, and further comprises at least 0.2% hydrogen peroxide bleach, characterised in that the composition is substantially free fiom hydrotropes. The composition may also comprise an optical brightener as defined above.

When present, the nonionic surfactant preferably comprises more than 5% by weight of the total composition and advantageously d e composition includes no more than 5% of surfactants winch do not satisfy d e pH criteria when tested according to Test A as described hereinafter. Most advantageously it comprises no more than 5% of surfactants which do not satisfy the residual peroxide criteria when tested according to Test A as described hereinafter.

The surfactant system is preferably a mbcture of anionic and nonionic surfactants, although entirely nonionic or anionic surfactant systems may be used. Compositions may contain an appropriate builder or be unbuilt Among the preferred anionic surfactants are:

a) Secondary alkane sulphonates, such as Hostapur SAS 93 a 93% active flake ex. Hoechst or Marion PS65 a sodium n-alkane (C_I}.₁₇) sulphonate with low sodium sulphate content ex. Huls;

b) Linear alkyl (C_{ιr 13}) benzene sulphonic acids such as Marlon AS3 ex Huls;

c) Alkyl ether sulphates such as Neopon LOS70, a 70% active sodium salt ex Witco; and

d) Olefin sulphonates such as Hostapur OS supplied as 40% actives ex Hoechst

Among die preferred nonionic surfactants are:

e) Primary alcohol (C₁₃.,_s) ethoxylates, erhoxylated with fiom 5 to 9 moles of ethylene oxide, preferably 7 moles, such as Synperonic A7 ex ICI / Cargo Fleet

The pH of the composition may lie in die range 7 to 12, and is preferably around 9.5.

The peroxide is preferably present as dissolved hydrogen peroxide in an amount by weight in the range 0.2 to 15% preferably 1 to 8% and most preferably around 5%.

The composition may also comprise minor components conventionally found in a heavy duty liquid detergent composition. These include perfume, suitably protected enzymes, surfactant preservatives, thickeners, colorants, builders, anti-redeposition agents, anti-dye transfer agents - poryvinylpyrroHdone (PVP) which acts bom as an aπthredeposition agent and an anti-dye transfer polymer is preferred - and other conventional additives.

The composition preferably contains sequestrants. Preferred sequestrants are sodium diedrylene triamine pentam.ahy.ene phosphonate, sold as Dequest 2066 by Monsanto, either alone or used with 2,2' dipyridylamine (DPA) or l,2'-diaminocyclohexyl tetrakis methylene phosphonic acid. Otiher sequejiering agents for transition metal ions may be used instead of, or in addition to, ώese preferred sequestrants.

In a preferred embodiment the compositions according to die invention are activated by use of a bleach activator such as TAF.D which may be brought into contact with the composition at the time of use by means of a two compartment dispensing system.

Accoiding to a πrd aspect of the invention the concentrated alkaline isotropic fabric washing liquid detergent composition may be used to pre-treat stained or other specific fabric localities before d e fabric is washed. In this process the stain removal is superior to tiiat which can be obtained fiom the known acid peroxide compositions and d e overall performance is enhanced by the high level of surfactant which is possible in compositions according to die present invention. The use of a concentrated fo-cmulation also confers the advantage of lower transport and packaging cost, which is environmentally desirable. according to any one of claims 1 to 11 to a selected area of the item, leaving it in contact with the item for a short treatment period and then washing die item. The treatment period will typically be 1 to 5 minutes, preferably about 2 minutes.

Compatibility of Surfactants with Peroxide

The following procedure, referred to as Test A is used for identifying suitable surfactants on de basis of pH and peroxide stability data. A trial foππulation is prepared using 20% w w (except Mariinat CM20 which was tested at 15% ww) of die surfactant to be screened. After sequestration with Dequest 2066, hydrogen peroxide sufficient to give a 5% w/w concentration of peroxide is added and d e pH is adjusted to 9.5 by die addition of pre-sequestered caustic solution. Details of the surfactants tested are given in Table 1. Table 1 - Surfactants tested

From experience we have derived die following pH and Peroxide Stability Targets. Residual peroxide is determined by permanganate titration. A surfactant should pass bom die pH and die peroxide targets. It is possible to use small (<5% preferred) amounts of surfactant which does not pass all die taigets, but this is only practical when die majority of the sur&ctants exceed die taigets by a good margin. As will be seen fiom d e test results in Table 2 it is possible to have satisfactory rcκ^*rmteπ-peratι^*fre -tabiliry even if die d Such surfactants would not be suitable for use in compositions destined to be stored at teπφeratures in excess of 30°C, which is often die case in warmer climates.

pH targets: pH^**5^ ^*> 9.0 after 12 weeks at 25°C H-'._j ^*> 7.5 after 12 weeks at 37°C ρH*⁵ ₄ ≥ 8.0 after 4 weeks at 45°C

Residual Peroxide targets:

Per²^ ^*> 85% after 12 weeks at 25°C

Per³⁷^ ≥ 50% after 12 weeks at 37°C Per ⁵ ₄ ≥ 55% after 4 weeks at 45°C

* 16 week data ** 8 week data *** 4 week data

The surfactants which pass botii die pH and peroxide stability tests are listed below (this eliminates die surfectantsfbr which good peroxide stability is due predominantly to a decrease in composition pH). A3 and A4 are inferior in terms of pH stability because me pH has drifted urwards for them. In practice an upward drift may not be a problem because d e benefits of an alkaline composition are retained.

In descending order of pH stability: Al > A4/A3 > N1 A6

In descending order of peroxide stability: NI > A6 > A3 > A4 > Al Gαnsklering bodi pH and peroxide stability, the preferred surfactants are therefore those listed above. Especially preferred for their combination of pH stability and peroxide stability are die secondary alkane sulphonates A3 and A4.

In addition to pH and peroxide stability, phase behaviour must also be suitable. We screened die s-n-factants which passed me pH and peroxide stability criteria and obtained die following results in a procedure which is referred to in this specification as Test B. Test B consists of measuring d e viscosity of a series of surfactant solutions w h concentrations increasing by increments of 5%. The concentration above which the viscosity exceeds a value of 1200 cps is referred to in this specification as die threshold concentration The test uses 1200 cps as being an approximate upper limit in terms of consumer acceptability. The level at which a particular surfactant is used in a liquid detergent should be below die threshold concentration, preferably by at least 5%, and more preferably by at least 9%. This is to allow for inaccurate dosing in the commercial manufacture of a liquid detergent and/or evaporation on storage. The results of die determination of the direshold concentrations for the preferred surfiictants is given in Table 3. The numbers in brackets are the viscosity in centipoise at 25°C, 21s^'1 of the aqueous solution of surfactant at die specified concentration.

Table 3 - Results of Test B

The itrv-ention will now be further described with reference to die following non-limiting examples:

Table 4 gives details of the example formulations. All composition data is on a 100% w/w basis.

Table 4

^•■•further NaOH is added to make me final pH adjustment

Fomrnilarions included PVP (polyvmylpyπOHdone) as an ant edeposition and anti-dye transfer agent and TINOPAL CBS-X, an optical brightener ex Ciba Geigy. Storage Data for die fomiulations at a range of isothermal storage conditions is given in Tables 5 to 9. Bodi pH and residual peroxide data is given Often, because peroxide is more stable under more acid conditions, a reasonable peroxide stability is obtained if there is a decrease in composition pH A pH drop is undesirable because it reduces die detergency and it makes it harder to activate die peroxide widi a bleach activator such as TAED. T_jφl ^** - Example. 1

Claims

1. A concentrated alkaline isotropic fabric washing liquid detergent composition comprising at least 15% by weight of surfactant and further comprises at least 0.2% by weight hydrogen peroxide bleach and an optical brightener, characterised in that the composition is substantially free fiom hydrotropes.

2. A composition according to claim 1 in which the composition comprises at least 20% by weight of surfactant.

3. A concentrated alkaline isotropic fabric washing liquid detergent composition comprising at least 23% of surfactants and further comprising at least 0.2% hydrogen peroxide bleach, characterised in that the composition is substantially free fiom hydrotropes.

4. A composition according to any preceding claim in which the surfactant comprises anionic and nonionic surfactant.

5. A composition accoiding to any preceding claim which further comprises an anti- redeposition agent.

6. A composition according to any preceding claim which further comprises an anti-dye transfer agent.

7. A composition according to any one of claims 4 to 6 in which the nonionic surfactant comprises more than 5% by weight of the total composition.

8. A composition according to claim 7 which comprises at most 5% of a surfactant which does not satisfy the pH targets when tested according to Test A as described herein.

9. A composition according to claim 8 comprising at most 5% of a surfactant which does not satisfy the residual peroxide targets when tested according to Test A as described herein.

10. A composition according to claim 6 wherein at least 95% of the surfactant comprises surfactants which are being used at a level below their threshold concentration as determined by Test B described herein.

11. A composition according to claim 3 in which all of the surfactants used satisfy the pH targets and preferably also the peroxide stability targets of Test A and are used at a level below their threshold concentration as determined by Test B.

12. A method of washing laundry with a wash liquor comprising adding to the wash liquor a composition according to any preceding claim together with a bleach activator, preferably TAED.

13. A method of pre-treating a laundry item comprising administering the composition according to any one of claims 1 to 11 to a selected area of the item, leaving it in contact with the item for a short treatment period and then washing the item.