WO1993003129A1

WO1993003129A1 - Concentrated hand dishwashing liquid composition having an alkane diol base

Info

Publication number: WO1993003129A1
Application number: PCT/GB1992/001415
Authority: WO
Inventors: Fred Kurt Rubin; David Van Blarcom; Jose Antonio Lopez
Original assignee: Unilever Plc; Unilever Nv
Priority date: 1991-08-02
Filing date: 1992-07-31
Publication date: 1993-02-18
Also published as: AU2363292A

Abstract

A concentrated light duty liquid detergent comprising 50 to 68 % of a mixture of anionic and non-ionic surfactants suspended in 9 to 18 % of an organic solvent, in particular an alkane diol having 3 to 6 carbons and no more than 2 hydroxy groups. The composition having no more than about 30 % of water, associated with the raw materials of the composition.

Description

CONCENTRATED ELAND DISHWASHING LIQUID COMPOSITION HAVING AN ALKANE DIOL BASE

The present invention relates to a hand dishwashing composition having a high level of surfactant actives and based on an organic solvent comprising an alkane diol.

Concern for the environment has provided an impetus to develop concentrated hand dishwashing liquid compositions. These concentrated compositions have a considerably higher level of surfactant actives than conventional detergent products. As a result of the high concentration of actives, these products can be sold in smaller plastic containers and consequently reduce the waste load of plastic materials. Additionally, the consumer uses appreciably less product in each washing operation: this brings savings in the cost of transporting the product and is convenient for the user. In use, the concentrated solution is diluted to a stock solution which while primarily intended for hand dishwashing can be used for a variety of household purposes. Important characteristics of hand dishwashing detergent liquids are foamability and effective soil removal without undue harshness to the user's hands. Other important characteristics are stability, clarity, mobility and low viscosity. It is difficult to formulate concentrated hand dishwashing liquids which meet all of these criteria.

It is well known that solvents may be used in concentrated detergent compositions. For example, US patent 2607740 discloses a liquid detergent composition incorporating sulphated and sulphonated detergents (40-60wt%) and alkanolamides (10-20wt%) . In that document, the use of solvents is suggested in order to overcome solubility problems at high concentrations of active, the preferred solvent being a mixture of water and ethanol

US 4555360 relates to a detergent composition comprising anionic surfactant, betaine and a ine oxide (as a foam booster) plus 1-90% water and 3-10% lower molecular weight alcohol. In addition, US 4554098 relates to liquid detergents having reduced skin irritation which include 30% alkyl ether sulphate, non-soap anionic, 1-8% zwit surfactant (selected from betaine, amido-betaine and sulphobetaine) and an alcohol as a solubiliser.

As an alternative to alcohols, other solvents have been proposed for use in laundry detergents. US 4747977 discloses laundry detergent compositions which avoid the odour and safety problems associated with alcohols and include 33wt% anionic surfactant, l-15wt% non-ionic surfactant and 4-25wt% of a polyol, selected from those having 4-6 carbon atoms and 2-4 hydroxyl groups, preferably 1,2, propane diol (propylene glycol) or alternatively trimethylene glycol, .diethylene glycol (2,2'oxy-bisethanol) , hexylene glycol (2-methyl-2,4 pentandiol) or glycerine. The compositions of this disclosure comprise about 20wt% to about 70wt% water. EP 109022 relates to a concentrated liquid detergent comprising a mix of anionic and non-ionic surfactants with solvents selected from alcohols, glycols, and ketones.

US 4671894 discloses a liquid dishwashing detergent comprising 4-20% alkyl sulphate, 5-20% alkylbenzene sulphonate, 1-10% non-ionic surfactant, 5-24% alkyl ethoxy sulphate, 0.25-10% zwitterionic surfactant (selected from alkylbetaine, alkyl-amidobetaine and sulphobetaine) and hydrotrope-water system in which the hydrotrope is selected from ethanol, urea, and/or lower alkyl benzene sulphonate. US 4088612 relates to compositions including sulphobetaines and anionic surfactant in molar ratio of not less than 1:2 in which lower alcohols are optional as hydrotropes. Hydrotropes are also known from EP 373851 which discloses a light duty liquid detergent including alkyl amidobetaines and alkyl amidosulphobetaines, 1-12% hydrotrope, optional electrolytes and an alkyl ether sulphate surfactant.

The present invention provides a liquid, stable, concentrated hand dishwashing compositions comprising less than 30% water and a mixture of anionic and non-ionic surfactants which comprise 9-18% of a 3-6 carbon alkane diol solvent having no more than 2 hydroxy groups.

No water need be added to these compositions to assist in the dispersion of the materials present, other than that which is present in the materials as supplied.

Preferably, the product comprises 35-65wt% of the anionic surfactant and l-15wt% of the non-ionic surfactant. It is particularly preferred to employ 40-50% anionics and 4-10% non-ionic. Typically, the formulations comprise at least 54% surfactant on product ie. 48-50wt% of anionic and 4- 10wt% non-ionic;

Suitable diols within the scope of the present invention are 1,2, propane diol, 1,4-butanediol, 2,3-butanediol, 2- methyl-2,4 pentanediol, 2,2'oxy-bisethanol, 1,2-pentane diol. The most preferred solvent is 1,2, propane diol.

It is preferable that the anionic actives include alkyl benzene sulphonate, alkyl ethoxy sulphate and secondary alkane sulphonate and mixtures thereof. In a preferred embodiment, the cation of the neutralised alkyl benzene sulphonic acid is mono-, di- or tri-alkalolamine, with the monoethanolamine particularly preferred. In a further preferred embodiment the anionic surfactants are alkylbenzene sulphonate and alkylethoxy sulphate in weight ratio's in a range of from 3:1-1:3. Preferably, the alkylethoxy sulphate is a C₁₂-C₁₃ or C₁₂-C₁₅ alcohol with an average of 3 moles of ethylene oxide per molecule.

The non-ionic component of the formulations is preferably an alkanolamide such as a C_X2-C₁₄ mono- or di-ethanolamide or an amine oxide or a mixture thereof. The ratio of the non-ionic component to the anionic component is preferably in the range 1:3 to 1:24 and most preferably 1:3 to 1:12. Optionally, an amphoteric component such as an amido- alkylbetaine, is added to improve performance and mildness.

Typical embodiments of the present invention provide a light duty liquid detergent suitable for hand dishwashing which comprises:

a) 35-65wt% anionic surfactant, b) l-15wt% non-ionic surfactant,

c) 9-18wt% alkane diol solvent having 3-6 carbons and no more than 2 hydroxy groups,

d) less than 30wt% water on product, said composition being free of added water.

Detailed Description of the Invention

Active Surfactants

The anionic active surfactants useful in the invention are alkylbenzene sulphonate, alkylethoxy sulphate and secondary alkane sulphonate and preferably alkylbenzene sulphonate and alkylethoxy sulphate. Additional anionics such as alkyl sulphates, alpha olefin sulphonates, etc. may also be suitable in the invention as known in the art. The anionic portion of the formula is in a range of from about 35 to about 65% by weight of the composition and may be composed of one or more anionics. In a preferred composition, the range of anionic proportion is from about 40 to about 55%, and most preferably 48 to 50%.

In preferred formulations, the alkyl benzene sulphonic acid is neutralised with its cation mono-, di- or trialkanolamine rather than alkali metal, alkaline earth metal or ammonium as used in conventional hand dishwashing liquids. In a particularly preferred embodiment, the monoethanolamine salt of alkylbenzene sulphonate is preferred.

The alkylethoxy sulphate (sodium, potassium, ammonium) used in the invention is derived from a C₁₂-C_n or C₁₂-C₁₅ alcohol having approximately 3 moles of ethylene oxide per molecule.

The secondary alkane sulphonate is preferably a sodium salt of a C₁₃-C₁₄ paraffin sulphonate.

In a preferred embodiment, mixtures of alkyl benzene sulphonate and alkylethoxy sulphate are combined in weight ratios varying respectively from 3:1 to 1:3. In particular, about 10 to about 20% of an alkylbenzene sulphonate is combined with about 25 to about 30% of an alcohol ethoxy sulphate.

The non-ionic component may be an alkanolamide such as C₁₂-C₁₄ mono- or diethanolamide or an amine oxide. In a preferred embodiment, cocodiethanolamide is used. About 1 to about 15% non-ionic surfactant preferably 4-10% is used. The ratio of the cocodiethanolamide to anionic surfactant may be in a range from about 1:3 to about 1:24, preferably 1:3 to 1:12. A non-ionic such as alkylpolyglycoside may replace a portion of the anionic component. A suitable alkylpolyglycoside has a C₁₂-C_1S alkyl chain and is linked to less than 2.0 polysaccharide units.

The amphoteric component of the formula imparts a degree of performance and mildness and is preferably an amidoalkylbetaine, and especially preferred is C₁₂-C₁₄ amidopropylbetaine. The amphoteric component is used in a range of 0 to about 10% by weight of the formulation.

Additional alkylamidobetaines which may also be used in the invention include cocoamidomethylbetaine, etc. as known in the art. Alkylamidobetaines useful in the invention are commercially available from Goldschmidt Inc. under the trademark Tego-Betaine.

Organic Solvents

In contrast with conventional aqueous detergent compositions, the formulations of the present invention do not utilise water to dissolve or disperse surfactants. Rather to suitably disperse and produce a stable suspension of ingredients to obtain a clear, mobile and low viscosity detergent formulation, an organic solvent system must be used.

Stable liquids of desirable physical properties are obtained by suspending the surfactants in about 9 to about 18% by weight of an alkane diol having 3 to 6 carbons and no more than 2 hydroxy groups. No more than about 30% water substantially associated with the raw materials used in the formulation may be present in the compositions. No free water is added to the formulation to assist in the dispersion of the components.

.Among the suitable diols are propanediol (propylene glycol), 1,4-butanediol, 2,3-butanediol, 2-methyl-2,4 pentanediol (hexylene glycol) and 2,2' oxybisethanol (diethylene glycol) and 1,2-pentanediol (pentylene glycol) . In a preferred embodiment, propylene glycol or hexylene glycol is used.

It was surprisingly found that a 2 carbon diol such as 1,2 ethane diol (ethylene glycol) did not produce a stable suspension but contributed to a phase separation in the formulation. Glycerol and sorbitol having 3 and 6 hydroxy groups respectively, are also unsuitable in the present invention because they induce rapid gel formation and eventually phase; separation.

Certain glycol ethers may be used as solvents but because of safety and environmental considerations as well as odour and cost are not preferred. Short chain alcohols such as ethanol and isopropynol induce flash points below 37°C and are unacceptable in formulating a consumer hand dishwashing liquid from a safety standpoint.

Optional ingredients which may be present in the light duty liquids include perfume, colourants, lemon juice and preservatives.

The pH of the compositions will generally range from about 6 to about 7.5, preferably about 7.

The compositions of the invention are stable and generally clear, although they may be opacified if desired.

The relatively low viscosity of the formulation provides a composition which may be easily dispensed by various means including pumps generally used with all-purpose cleaners and window wash products.

Moreover, the composition may be used directly on surfaces to be cleaned or may be diluted. Upon dilution the viscosity of the formulation increases until a dilution of about 1.1 composition to water has been reached. At a dilution of greater than 1:1 of water to composition, the viscosity decreases.

The light duty liquid detergent of the invention does not generally include a polymeric surfactant, cationic polymers, a clay or an abrasive, although inclusion of such ingredients may be appropriate in certain circumstances.

While the light duty liquid detergent compositions of the invention are primarily adopted to use as hand dishwashing detergent, their use is not limited thereto. For example, it may appropriate to utilise the formulations for general purpose cleaning, hand fabric washing and the like.

PREPJ-RATION PROCESS FOR CONCENTRATED HAND DISHWASHING LIQUIDS

The anionic component, such as alkylethoxysulphate, is put into a mixing vessel and the alkane diol and the monoethanolamine, if alkyl benzene sulphonic acid is selected as the second anionic, are added with gentle agitation. Monoethanolamine serves to neutralise the alkylbenzene sulphonic acid, if present, resulting in the formation of monoethanolamine alkylbenzene sulphonate. The quantity of monoethanolamine added is based on the activity and sulphuric acid content of the alkylbenzene sulphonic acid.

The temperature of the blend is kept at (or brought to) 16°-27°C before the slow addition of the second anionic, such as alkylbenzene sulphonic acid. During the latter addition, the batch temperature has to be cooled to below 52°C. After addition of the alkylbenzene sulphonic acid, an adjustment of pH to about 5 is made by means of small additions of monoethanolamine or alkylbenzene sulphonic acid. In formulations without alkylbenzene sulphonate, the respective replacements are added instead. The amphoteric component, if present, is added next, followed by alkyldiethanolamide or amine oxide. Each addition is accompanied by agitation.

The final additions consist of colourants, lemon juice (if required by the formula) and perfume. The colourants are dispersed in a small quantity of alkane diol prior to

_* addition to the batch.

After all components have been added, the batch is adjusted to pH 6.5-6.7; it then is ready for transfer to storage containers.

The following examples are included to more fully describe the preferred embodiments of the present invention and are ot included to be limiting in any manner.

Example 1

This example shows two conventional, commercially available hand dishwashing liquids. The compositions are shown on a weight percent active basis.

Example II

This example illustrates the criticality of the diol solvent. All compositions are formulated on a weight percent active basis.

Monoethanolamine 20.0 20.0 20.0 20.0 alkylbenzene sulphonate

-Ammonium 29.0 29.0 29.0 29.0 alkylethoxysulphate

Cocodiethanolamide 7.0 7.0 7.0 7.0

1,2-Propanediol 12.0 12.0

1,2,3-Propanetriol 12.0 (glycerol)

Sorbitol¹ 12.0

Water added 5.14

Water from raw 14.5 14.5 14.5 19.64 materials

Miscel. ingredients (colourants, perfume, Balance to 100%- le on juice, etc.)

Active content % 56.0 56.0 56.0 56.0

Physical appearance clear, non- clear, thick mobile uniform, mobile paste liquid mobile liquid with gel exudate

^xThe sorbitol used was a 70% aqueous solution, hence 12.0% sorbitol, active basis, is equivalent to 17.14% of the 70% sorbitol solution; hence sorbitol introduces 5.14% water into the composition. ²Water was added to Composition E (propanediol) to match the quantity of water carried into composition F by sorbitol. This was done to determine whether or not the water in the sorbitol solution was responsible for the destabilisation of composition F. 5.14% extra water does not cause the destabilisation of the composition.

The compositions were made as described above.

The above examples show clearly that the triol (glycerol) and the hexahydroxy compound sorbitol are unsuitable as solvent/carriers for the ingredients of the concentrated compositions.

Example III

This example is a further illustration of the criticality of the solvent. While diols with three to six carbons are effective solvents, the two carbon diol 1,2-ethanediol (ethylene glycol) is unsuitable as it does not permit preparation of stable compositions.

All compositions are formulated on a weight percent active bases and made as described above.

10

15

Freezing points, sometimes referred to as "cloud points", are indicators of the low temperature stability of compositions. Freezing points (f.p.) below -1.1°C indicate adequate stability of a composition on exposure to low temperatures which, in the case of a consumer product, may occur during shipping or warehousing of the product. The f.p. of composition H is 3.9°C which indicates a potential sensitivity to low temperatures that could result in irreversible phase separation on severe freezing. At in-home temperatures ranging from 15.6- 29.4°C, however, composition H is entirely stable. Compositions I to L have low f.p. and are not expected to be adversely affected by low temperatures.

Correlation exists between the position of the hydroxy group of a diol and freeze point. The terminal carbon (1,4) position of the hydroxy groups in 1,4-bu anediol leads to a composition (J) with higher f.p. (-9.4°C) than a parallel composition (K) based on 2,3-butanediol in which the hydroxy groups are positioned on vicinal carbons and the f.p. is well below -12.2°C. Diethylene glycol, which was used in composition H, also has the hydroxy group in the 1,4 position.

Example IV

The following compositions represent additional stable and useful concentrated hand dishwashing liquids. The compositions are shown on a weight percent active basis and were made as described above.

Example V

Performance Tests

Sudsing Test

Prior to evaluation by actual plate washing, the sudsing characteristics of the concentrated hand dishwashing compositions were assessed by means of a suds generating laboratory apparatus. The apparatus consists of a rotating platform on which are strapped graduated measuring cylinders containing aqueous solutions of the samples to be tested. A lid s fastened over the cylinders and suds are generated by forty revolutions of platform and cylinders. After initial suds formation, a small measured quantity of a mixed fat/carbohydrate/protein model soil is added to each cylinder and the revolving of the cylinders repeated. The soil addition/cylinder revolution procedure is repeated until the suds have dissipated. The cumulative suds volume of each sample is then compared against a control. High cumulative suds volumes are indicative of good sudsing performance in an actual hand dishwashing situation.

Both samples below were used at 0.15% concentration in water of 118 ppm hardness.

Cumulative Foam Volumes ml

Composition M 4950.0 Commercial Product A 2283.5 In the following case, both products were used again at 0.15% concentration and at a water hardness of 120 ppm. Another sample σf the commercial product was used.

Composition I Commercial Product A

The above data clearly show that at equal use concentrations, the concentrated compositions generate well over twice the suds volumes of the commercial product.

Plate Wash. Test

The concentrated hand dishwashing formulations were further evaluated in a "latin square" design plate washing test versus commercial products. In the test, plates were alternatively soiled with pre-measured quantities of a mix of mashed potato/beef gravy and with spaghetti sauce (Ragu brand) . The soils typically represent the protein, carbohydrate and fat components of household foods. The soiled plates were hand washed in detergent solutions of different use concentrations contained in hand wash bowls of six quart capacity. Prior to washing, suds were generated in the wash bowls by controlled mechanical means. Composition L Commercial Product A

Use concentration % 0.075 0.15 Number of soiled plates washed*

Water hardness - 30 ppm 53.25 53.0

- 120 ppm 53.13 52.5

Four wash average

Composition L Commercial Product B

Use concentration % 0.067 0.10 Number of soiled plates washed*

Water hardness - 30 ppm 43.3 42.5

- 130 ppm 43.0 45.8

Use concentration % 0.033 0.05

Number of soiled plates washed*

Water hardness - 180 ppm 32.0 29.5.

According to test results, a typical concentrated hand dishwashing composition such as Composition L (Example III) exhibits 100% greater washing efficacy than commercial product A (Example I) and 50% greater efficacy than commercial product B. The efficacy advantage is noticeable at different water hardnesses. Example VI

This example illustrates the effect of dilution with water upon the concentrated products' viscosities. As water is being added to the concentrates, viscosity will increase until at a dilution of around 1:1 it characteristically begins to decrease.

Composition I - Example III

Composition L - Example III

Composition Q - Example VI

Further work on concentrated hand dishwashing liquids is in progress and additions to the patent data will be made at a later date.

Claims

CLAIMS ;

1. Liquid, stable, concentrated hand dishwashing compositions comprising less than 30% water and a mixture of anionic and non-ionic surfactants which comprise 9-18% of a 3-6 carbon alkane diol solvent having no more than 2 hydroxy groups.

2. Composition according to claim 1 comprising 35-65wt% of the anionic surfactant and l-15wt% of the non-ionic surfactant.

3. Composition according to claim 1 wherein the diols is selected from the group comprising: 1,2, propane diol, 1,4-butanediol, 2,3-butanediol, 2-methyl-2,4 pentanediol, 2,2'oxy-bisethanol, 1,2-pentane diol.

4. Composition according to claim 1 wherein the anionic surfactants comprise alkyl benzene sulphonate, alkyl ethoxy sulphate and secondary alkane sulphonate and mixtures thereof.

5. Composition according to claim 4 wherein the anionic surfactants are alkylbenzene sulphonate and alkylethoxy sulphate in a weight ratio from 3:1-1:3.

6. Composition according to claim 5 wherein the alkylethoxy sulphate is a C₁₂-C₁₃ or C₁₂-C₁₅ alcohol with an average of 3 moles of ethylene oxide per molecule.

7. Composition according to claim 1 wherein the weight ratio of the non-ionic component to the anionic component is in the range 1:3 to 1:24, preferably 1:3 to 1:12.

8. Composition according to claim 1 comprising;

a) 35-65wt% anionic surfactant, selected from the group comprising: alkyl benzene sulphonate, alkyl ethoxy sulphate and secondary alkane sulphonate and mixtures thereof,

b) l-15wt% non-ionic surfactant, selected from the group comprising: alkanolamide, amine oxide and mixtures thereof,

c) 9-18wt% alkane diol solvent selected from the group comprising: 1,2, propane diol, 1,4- butanediol, 2,3-butanediol, 2-methyl-2,4 pentanediol, 2,2'oxy-bisethanol, 1,2-pentane diol and mixtures thereof, and

d) less than 30wt% water on product, said composition being essentially free of added water.