WO1996030485A1

WO1996030485A1 - Alkaline isotropic liquid detergent with peroxide

Info

Publication number: WO1996030485A1
Application number: PCT/GB1996/000644
Authority: WO
Inventors: Michael John Day
Original assignee: Warwick International Group Ltd
Current assignee: Warwick International Group Ltd
Priority date: 1995-03-24
Filing date: 1996-03-18
Publication date: 1996-10-03
Anticipated expiration: 1997-09-24
Also published as: AU5114896A; GB9506066D0

Abstract

Concentrated aqueous alkaline isotropic liquid detergent composition comprising a mixture of nonionic and anionic surfactants and dissolved hydrogen peroxide. The mixture also contains a hydrotrope selected from the group comprising polyhydric alcohols with a flashpoint greater than 30 °C, other alcohols with a flashpoint greater than 30 °C or mixtures thereof. The composition is suitable for use as a laundry detergent and since it is substantially free from ethanol or other C1-4 monohydric alcohols, stability of the composition is increased and the danger of explosion from a mixture of low flashpoint alcohol and peroxide is reduced.

Description

^• .K&T.TMB TSOTROPTΓ LIQUID DETERGENT TTH PEROXIDE

This invention relates to aqueous alkaline isotropic liquid detergent compositions particularly to compositions containing hydrogen peroxide and a surfactant system including an anionic surfactant.

Aqueous isotropic liquids containing surfactant and peroxide often contain ethanol. However, the use of this solvent is undesirable when hydrogen peroxide is present because of the danger of explosion due to the low flashpoint of the ethanol.

W093/14183 describes liquid detergent compositions containing anionic and/or nonionic surfactant, oxygen bleach and a metal sequestering agent to prevent discoloration with time. The canposition may also contain a hydrotrope. Useful hydrotropes are stated to be alcohols such as ethanol and propylene glycol at a level of 0 to 15%; sodium and potassium toluene, xylene or cumene sulphonate at levels from 0 to 10%; and urea at a level of 0 to 10%. Exartple 1 uses a mixture of atrrmonium xylene sulphonate (4%) and ethanol (5.5%) . The level of peroxide is only 0.18% and the pH is 7.1 in this and the other examples in this patent specification. All examples are rich in anionic surfactant.

US 4 507 219 describes heavy duty liquid detergents in the form of isotropic liquids. A chlorine bleach can be added and the compositions are stated to be compatible with the bleach. A preferred solvent system is said to be a mixture of ethanol, a polyol and water. Propylene glycol is the preferred polyol. It is stated that the composition may also contain hydrotropes. There is no suggestion to use an oxygen bleach.

US 4 470 919 describes a liquid detergent composition containing hydrogen peroxide, surfactant, fatty acid and a calcium salt. Preferred anionic surfactants include alkylbenzene sulphonates, alkyl sulphates and alkyl ether sulphates. The pH of the composition must be less than 9. The compositions may contain a phase regulator such as ethanol, n-propanol, isopropanol, butanol, propane-1,2-diol, propane-1,3-diol, n-hexanol; 2-methyl,2,4- pentanediol, monomethyl-, ethyl and propyl and monobutyl- ethers and di-ethylene glycol. The composition may also include known detergent hydrotropes e.g. sodium, potassium and ammonium salts of xylene, toluene, ethyl benzene and cumene sulphonic acids. Examples use only ethanol and propane-1,2-diol.

EP 0 037 184 describes an aqueous detergent composition containing peroxide and an alcohol stabiliser system. Built anionic rich and unbuilt nonionic rich compositions are disclosed. Ethanol is always used, along with a sodium xylene sulphonate (SXS)hydrotrope for these compositions.

In related patent specification EP 0 076 166 there is described an aqueous detergent composition containing peroxide and an alcohol stabiliser system. Isopropanol is stated to be preferred over ethanol because of its higher flashpoint. In fact the flashpoint of 2-propanol is almost the same as ethanol and both lie below 20°C. The examples disclose the use of 6% anionic surfactant (linear alkylbenzene sulphonate) , 4% nonionic surfactant (primary alcohol ethoxylate) and 6% of the sulphonate hydrotrope ELTESOL SX30 (SXS) in addition to the peroxide and isopropanol. Some of the examples contain a builder which is either potassium tetrapyrophosphate or sodium citrate.

Despite the clear preference in prior art peroxide formulations for combinations of solvents which include ethanol we have found a range of stable formulations which contain the much higher flashpoint propylene glycol, butyl carbitol or hexylene glycol or other high flashpoint alcohols as a major solvent hydrotrope.

WO 92/02607 describes an aqueous liquid bleaching composition with good storage characteristics. It contains a surfactant system comprising a mixture of soap, alkyl polyglucoside and sodium fatty alkyl sulphate with a major part of C₁₂ fatty substituent. The formulations also include ethanol, propane-1,2-diol (propylene glycol) and diethylenetriaminepentamethylene phosphonate. The pH of the formulations is about 7.

According to the present invention there is provided a concentrated aqueous alkaline isotropic liquid detergent composition with a pH greater than 7.5 comprising a mixture of nonionic surfactant and anionic surfactants and dissolved hydrogen peroxide in an amount by weight in the range 0.2 to 15% characterised in that it also comprises from 5 to 25 % of a hydrotrope selected from the group comprising polyhydric alcohols with a flashpoint greater than 30°C or other alcohols with a flashpoint greater than 30°C or mixtures thereof and the composition is substantially free from ethanol or other Ci-₄ monohydric alcohols.

Flashpoint is measured by closed cup methods. It is preferred that the flashpoint of the neat alcohol is greater than 50°C, most preferably greater than 70°C. The anionic co-surfactant may be a linear alkylbenzene sulphonic acid (LAS) . A preferred anionic surfactant is lauryl ether sulphate (LES) . When the composition has LAS as the anionic surfactant the high flashpoint hydrotrope is selected from the group comprising propane-1,2-diol, also known as propylene glycol, 2-methyl-2,4-pentanediol also known as hexylene glycol, and 2- (2- butoxyethoxy)ethanol also known as butyl carbitol, or diethylene glycol monobutyl ether. When the composition has LES as the anionic surfactant the high flashpoint hydrotrope is selected from the group comprising hexylene glycol and butyl carbitol, preferably hexylene glycol.

The advantage of the cottposition being substantially free from ethanol or other lower C^ monohydric alcohols is that this increases stability and reduces the danger of explosion from the mixture of low flashpoint alcohol and peroxide. It also reduces the amount of odour due to evaporation of volatile material.

In this specification the term anionic rich means that the amount by weight of nonionic surfactant makes up less than or equal to

50% of the total of all anionic and nonionic surfactants.

Nonionic rich means that the proportion of nonionic surfactant is greater than 50% by weight of the total of all anionic and nonionic surfactants in the composition. Anionic rich compositions may contain builder or be unbuilt. If the composition is anionic rich, the total amount of surfactant in the composition preferably lies in the range 20 to 70% by weight, most preferably 30 to 45% for unbuilt anionic rich compositions. Anionic rich compositions may additionally comprise up to 30% of a builder, preferably up to 10% sodium citrate; for built anionic rich compositions the total amount of surfactant in the composition preferably lies in the range 20 to 50%, most preferably 30 to 50% by weight.

Preferred nonionic surfactants are alcohol ethoxylates such as C_8- ₂₄, preferably C_10-16, alcohols which have been ethoxylated using l to 20 moles, preferably 3 to 12 moles of ethylene oxide per mole of alcohol; alkyl phenol ethoxylates,- alkyl polyglycosides, particularly alkyl polyglucosides,- amine oxides and mixtures thereof. The composition may additionally contain other surfactants chosen from amphoteric, zwitterionic and cationic surfactants.

When the composition is nonionic rich the anionic surfactant is a linear alkylbenzene sulphonic acid (LAS) or preferably lauryl ether sulphate (LES) and the total surfactant level lies in the range 35 to 60% by weight.

An alternative or additional hydrotrope may be selected from a group comprising aπinonium, sodium and potassium salts of toluene, xylene and cumene sulphonate at levels up to 20%, preferably SXS is used. The combination of a hydrotrope of this type with a high flashpoint polyol in a composition according to the invention may provide the advantage of reduced pH drift whilst maintaining the high peroxide levels and thereby maintains detergency and stain removal properties of the formulation.

The pH of the composition may lie in the range 7.5 to 12, preferably around 9.5.

The hydrogen peroxide is preferably present in an amount by weight in the range 0.2 to 15% more preferably 0.2 to 8% and most preferably around 5%. The composition may also comprise minor coπponents conventionally found in a heavy duty liquid detergent composition. These include, perfume, enzymes, optical brighteners, preservatives, thickeners, colorants, builders, anti-redeposition agents or anti-dye transfer agents, such as polyvinylpyrrolidone (PVP) and other conventional additives.

The cottposition preferably contains sequestrants. Preferred sequestrants are sodium diethylenetriaminepentamethylene- phosphonate, sold as Dequest 2066 by Monsanto, 2,2' -dipyridylamine

(DPA) and 1,2 ' -diaminocyclohexyl tetrakis methylene phosphonic acid. Other sequestering agents for iron, cobalt, copper and manganese ions may be used instead of or in addition to these preferred sequestrants.

The invention will now be further described with reference to the following non limiting examples:

In the examples the nonionic surfactant used was SYNPERONIC A7 a 90% solution C₁₃.₁₅ 7E0 primary alcohol ethoxylate ex Cargo Fleet. The anionic surfactant was either MARLON AS3 a _₀.^ linear alkylbenzene sulphonic acid ex Huls, or NEOPON LOS 70 a sodium lauryl ether sulphate ex Baxenden chemicals. The initial %H₂0₂ was 5.0 and the initial pH was about 9.5. A mixed sequestrant system of Dequest 2066 and Dipyridylamine was used. All formulations contain sodium hydroxide to adjust the final pH of the composition and also to neutralise the LAS in situ where it is used. Formulations also included PVP as an anti-redeposition and anti-dye transfer agent and TINOPAL CBS-X, a fluorescer ex Ciba Geigy.

All the formulations were made using the same basic process. To water at 25°C is added sodium hydroxide, hydrotrope(s) , surfactants, sequestrant(s) , PVP and fluorescer before addition of the peroxide. The liquid is mixed and the pH is adjusted with sequestered sodium hydroxide. For processing reasons ingredients are preferably added as liquids. Solid ingredients such as SXS could be added directly in order to reduce the water contribution from an aqueous solution additive, however, this would only be preferred for very high levels of surfactant. The composition of the examples in % by weight of the active ingredient, or % solids is given in Table 1. Minors includes the sequestrants (Dequest 2066 and DPA) , anti-redeposition agent (PVP) and the TINOPAL CBS-X.

Table 1 - Composition of Examples

(wt.%) 1 2 3 A 4 B 5 6 7 c

Nonionic 24.5 24.5 24.5 24.5 12.2 12.2 31.5 31.5 30.0 31.5

LAS 10.5 10.5 10.5 10.5 22.8 22.8 13.5 - - 13.5

LES - - - - - - - 13.5 10.0 -

NaOH 1.3 1.3 1.3 1.3 2.9 2.9 1.7 0.2 0.2 1.7

Builder - - - - 4.0 4.0 - - - -

SXS - - - 12.5 - 12.5 - - 9.0 12.5

Propylene 12.5 "" ~ 12.5 12.5 ~ ~ ~ glycol ^"

Hexylene 12.5 - ~ - ~ 16.0 9.0 ~ glycol ^"

Butyl ~ ~ 12.5 ~ ~ ~ ~ - - ~ carbitol

H 5.0

Minors 1.16

Water to 100

RxamplPR I 2. 3 and comparative example A

These examples each contained 35% total surfactant and were formulated with a 70/30 ratio of nonionic to anionic. The anionic surfactant was LAS. In comparative example A the hydrotrope was SXS. The %HA was measured by permanganate titration initially and after storage for specified periods of time at constant temperature. Results are given in Table 2 for storage at 25°C and 37°C.

Table 2 - tH_0_ loss

Eg(°C) 1 week 2 weeks 4 weeks 8 weeks 12 weeks 26 weeks

1(25) 2.2 2.7 3.6 9.4 10.6 9.4

2(25) 0.0 1.0 1.6 7.9 10.1 16.3

3(25) 1.0 2.4 4.6 11.3 12.9 17.1

A(25) 1.8 3.2 5.8 10.7 16.9 22.4

1(37) 7.4 8.9 10.1 11.0 12.4 13.8

2(37) 1.6 7.5 10.3 - 15.5 15.1

3(37) 1.4 8.1 12.5 - 17.3 17.3

A(37) 5.8 9.1 15.5 17.7 18.3 18.1

It can be seen that the drop in %H₂θ₂ is slower for the examples formulated with a hydrotrope according to the invention compared with those formulated with SXS. Exaπple 4 anrl comparative example B

These are built anionic rich formulations with a 35% total level of surfactant and a 35/65 ratio of nonionic to anionic. %H-0₂ lost data is given in table 3. Again it can be seen that the formulation with the polyol is losing peroxide slower than that formulated with SXS.

Table 3 - H_ _ loss

Eg(°C) l week 2 weeks 4 weeks 8 weeks 12 weeks 26 weeks

4(25) 3.6 3.6 8.7 13.3 17.5 22.6

B(25) 11.3 22.6 50.7 76.8 85.6 92.7

4(37) 6.5 8.9 14.1 15.5 19.6 22.0

B(37) 26.9 47.2 76.4 85.8 90.8 94.8

Examples 5. 6 and 7 and Comparative example C

Example 5 is a 45% total surfactant formulation with a 70/30 weight ratio of nonionic to anionic. The hydrotrope is propylene glycol. Comparative example C is the equivalent formulation with SXS for comparison. Examples 6 and 7 contain LES in place of the LAS. Example 6 has 45% total surfactant. Hexylene glycol was used instead of propylene glycol for this example. Example 7 has 40% total surfactant with a 75/25 nonionic/anionic ratio and a mixed hydrotrope 50/50 hexylene glycol/SXS system. %H₂θ- loss data for 25°C and 37°C extended storage are given in Table 4.

Table 4 - iH,0, loss

Eg(°C) 1 week 2 weeks 4 weeks 8 weeks 12 weeks 26 weeks

5(25) 0.0 - 4.7 7.8 12.1 10.9

6(25) 0.0 1.0 0.0 5.5 7.9 9.1

7(25) 4.1 1.6 4.3 7.7 12.0 20.8

C(25) 1.2 1.2 5.2 9.1 13.9 16.5

5(37) 4.5 7.2 8.2 10.5 13.1 12.5

6(37) 0.6 1.6 2.0 6.5 10.5 7.5

7(25) 4.7 5.3 8.4 15.1 19.8 18.9

C(37) 2.4 8.5 10.7 16.7 17.9 18.6

Claims

_________

1. A concentrated aqueous alkaline isotropic liquid detergent composition with a pH greater than 7.5 comprising a mixture of nonionic surfactant and anionic surfactants and dissolved hydrogen peroxide in an amount by weight in the range 0.2 to 15% characterised in that it also comprises from 5 to 25% by weight of a hydrotrope selected from the group comprising alcohols with a flashpoint greater than 30°C and the composition is substantially free from C_1-4 monohydric alcohols.

2. An aqueous alkaline isotropic liquid detergent formula ion according to claim 1 wherein the hydrotrope is selected from the group comprising alcohols with a flashpoint greater than 50°C, preferably greater than 70°C.

3. An aqueous alkaline isotropic liquid detergent formulation according to claim 1 or 2 wherein the composition comprises at least 35% total surfactant when nonionic rich or at least 20% total surfactant when anionic rich.

4. An aqueous alkaline isotropic liquid detergent formulation according to any preceding claim wherein the composition is nonionic rich and the anionic surfactant is a linear alkylbenzene sulphonic acid or lauryl ether sulphate.

5. An aqueous alkaline isotropic liquid detergent formulation according to any preceding claim wherein the high flashpoint alcohol is selected from the group comprising propane-1,2- diol, 2-methyl-2,4-pentanediol, and 2- (2-butoxyethoxy) ethanol.

6. An aqueous alkaline isotropic liquid detergent formulation according to any preceding claim wherein the composition comprises a further hydrotrope selected from the group comprising ammonium, sodium and potassium salts of toluene, xylene and cumene sulphonate at levels up to 20%.

7. An aqueous alkaline isotropic liquid detergent formulation according to any preceding claim wherein the surfactant part of the composition is anionic rich and the formulation also comprises a builder, preferably sodium citrate.

8. An aqueous alkaline isotropic liquid detergent formulation according to any preceding claim wherein the hydrogen peroxide is present in an amount by weight in the range 0.2 to 8% and most preferably around 5%.

9. An aqueous alkaline isotropic liquid detergent formulation according to any preceding claim wherein the pH of the composition is greater than 8, preferably greater than 9.