WO1994003581A1

WO1994003581A1 - Liquid detergent composition

Info

Publication number: WO1994003581A1
Application number: PCT/GB1993/001610
Authority: WO
Inventors: Symon Paul Clowes; Paul Lawrence Heffernan
Original assignee: Cussons (International) Limited
Priority date: 1992-08-01
Filing date: 1993-07-29
Publication date: 1994-02-17
Also published as: AU4718693A; GB9501489D0; GB9216570D0; PL307266A1; GB2284823A

Abstract

A liquid detergent composition comprises soap, builder or dispersant and hydrotrope. The soap is made in situ by saponification of an oil or fat in the presence of the builder/dispersant and hydrotrope. The composition optionally comprises one or more non-soap surfactants in an amount not exceeding 20 % of the weight of the soap.

Description

LIQUID DETERGENT COMPOSITION

The present invention relates to a liquid detergent composition and particularly but not exclusively to a heavy duty liquid laundry detergent composition and a method of manufacture of said composition.

It is known to manufacture laundry detergent compositions comprising soap as an active ingredient. Soap acts both as a builder and a surfactant while at the same time improves the softness of the washed fabric. The prior art soap containing formulations are conventionally made by neutralising fatty acids with base. Alternatively soap can be made from the saponification of fats. This may involve mixing the fat and base at a high temperature for a considerable period of time, for example about 100°C for three or more hours. Such detergent compositions are expensive to produce either because of the high cost of fatty acids or the high amount of energy and time normally need to saponify fats.

The present invention has been made from a consideration of this problem.

According to a first aspect of the present invention there is provided a method of making a detergent composition comprising water, at least one soap as a major proportion of the surfactant system of the composition, at least one builder or dispersant and at least one hydrotrope, said method comprising the step of producing the soap in situ by saponification of an oil or fat in the presence of the builder/dispersant and hydrotrope.

The in situ saponification is facilitated by the builder and hydrotrope. The water acts as a solvent and the reaction medium.

The oil or fat acts as the precursor to the soap. The oil or fat preferably comprises triglyceride which may be derived from animals or more preferably vegetables. The preferred chain length of the oil or fat is C^,2 ^{to C}22' ^more preferably C^, « to C₂₀ and ideally C, _g to C,o- The oil or fat may be saturated, poly unsaturated but is preferably mono unsaturated.

Any suitable base may be used. Strong bases are preferred such as hydroxides of group one metals e.g. sodium hydroxide and potassium hydroxide. It is evident that three moles of hydroxide would be needed to react with each mole of triglyceride to produce three moles of soap and one mole of glycerol.

Known soap containing liquid laundry compositions generally comprise a blended active system of soap and non-soap surfactants, the soap to non-soap surfactants ratio typically being in the range from 1:2 to 2:1. It has previously been considered undesirable to provide a blend of soap and non-soap surfactants outside this range.

According to a second aspect of the present invention there is provided a liquid detergent composition comprising at least one soap and optionally at least one non-soap surfactant in an amount not exceeding 20% of the weight of the soap.

If the soap makes up 80% or more of the surfactant system the composition will exhibit improved detergency on a range of test soils when compared to formulations of the same total active content with ratios of soap to non-soap surfactant in the range from 1:2 to 2:1.

In a preferred embodiment of the invention the non-soap surfactant content does not exceed 15% of the weight of the soap.

The compositions of the present invention are substantially unstructured. Thus the builder and surfactants should be substantially in solution.

The non-soap surfactants may be nonionic, anionic, cationic or zwitteronic . These additional surfactants aid the detergency of the finished product and assist in the saponification reaction by emulsification of the oil and water phases. Preferably the detergent comprises from 0% to 40.0% by weight of the additional surfactants.

The detergent composition preferably comprises from 1.0% to 47.0% by weight of soap. The amount of triglyceride and base to be added to the reaction mixture may be varied accordingly.

The builder and/or dispersant preferably comprises any of the following: phosphate, carbonate, carboxylate, citrate, phosphonate or silicate. Phosphate containing builders are preferred.

The detergent composition preferably comprises from

1% to 30.0%, but preferably no more than 25% weight of builder. The builder acts to enhance detergency by sequestration (chelation) of metal ions, dispersion of soil in the wash liquor and by providing alkalinity. The builders also function as a process aid by assisting the saponification reaction by dispersing the oil/fat as droplets thereby maximising the contact area of the reactant phases of oil and water. Furthermore the builders also reduce the process viscosity which facilitates more efficient mixing .

The hydrotrope preferably comprises any of the following: alcohols, glycols, xylene sulphonate, toluene sulphonate or cummene sulphonates. The detergent composition preferably comprises from 0.05 % to 20.0% by weight of hydrotrope. The hydrotropes assist in the solubilisation of ingredients and assist in the saponification reaction by increasing the solubility of the soap. This in turn aids the emulsification process. The detergent composition preferably comprises an effective amount of a proteolytic, amylolytic or lipoltytic enzyme. The composition preferably further comprises an effective stabilising system. The composition may further comprise any of the following: optical brightening agent, foam boosting agent, preservative, perfume, dye or anti redeposition agents.

In addition the composition may comprise further minor ingredients which are conventionally used in detergent compositions such as colouring agents or fragrance.

The process of the present invention typically comprises the following steps.

Water is charged into a reaction vessel and the base, builders and hydrotropes are dissolved in the water. Any additional surfactants are also added at this stage. Oil and/or fat is then charged into this solution. The batch is heated to the required temperature (in the order of 75°C) whilst being mixed. Mechanical agitation may be required here. The batch is maintained above a specified minimum temperature until the chemical reaction is complete. The reaction progress is monitored by the determination of free base possibly by titration with hydrochloric acid. When the required reaction temperature is achieved the reaction accelerates exothemically producing a further temperature increase. As the reaction proceeds the viscosity of the mixture slowly increases to a maximum and then rapidly decreases as the reaction nears completion. The batch is subsequently allowed to cool to a suitable temperature at which the remaining ingredients can be added sequentially.

Normally the saponification process has three stages:

(i) Slow incubation period (ii) Rapid exothermic stage (iii) Gradual completion.

(i) The incubation period is slow due to poor contact between the aqueous and oil phases. As the amount of soap produced increases a greater amount of oil is emulsified. This accelerates the reaction to the next stage.

(ii) Once significant levels of soap have been produced emulsification becomes more efficient causing the reaction to proceed rapidly and self-catalytically. The saponification reaction is exothermic . A temperature rise is observed owing to the accelerated rate of reaction.

(iii) The reaction progressively slows down due to the reduced concentration of reactants . This can take many hours for the reaction to approach completion.

The process of the present invention offers a number of significant advantages some of which are discussed below:

(i) The incubation period is accelerated due to the dispersing properties of the builders and additional surfactant present and the solubilising effect of the hydrotrope.

(ii) The exothermic stage proceeds at a more rapid rate resulting in a greater temperature rise. This enables the temperature to which the batch must be heated to be reduced, thereby saving on energy costs. (iii) The increased efficiency of the process results in the final stage being rapid rather than gradual.

The following example liquid laundry compositions were made by the method previously described.

5.00 5.00

5.00 25.00

25.00

30.00

S.15 6.18 5.15 2.00 5.00 2.00 2.00 2.00

8.00 10:00

4.00

5.00 4.00 7.00 4.00 5.00 4-00 0.10 0.10 0.20 4.00 5.00 4.00 0.20 0.20 0.20 0.50 0-SO 0.50 0.004 0.004 0.004 to 100* to 100* to 100*

1⁾ Synperonic A7 - Nonionic surfactant ex ICI based on C₁₃ - C₁₅ fatty alcohol with 7 ethoxylate groups.

2) Sinopal 1100 - S88 - Nonionic surfactant ex Sino-Japan Chemical Co Ltd - polyoxyethylene lauryl ether. 3) Dequest 2066 - 25% solution of diethylenetriamine penta (methylene phosphonic acid) heptasodium salt - ex monsanto.

4) Tinopal CBS-X- optical brightener ex Ciba-Geigy.

Detergency evaluation of blends of soap (predominantly C,_R. mono-unsaturated) with the anionic detergent Alkyl (C,,-C, -.) Benzene Sulphonate demonstrate, for certain soils, a substantially linear increase in detergency as the proportion of soap increases, and in other cases detergency passes through a minimum in the region of typical prior art formulations.

The results of the tests are shown in Figs. 1 to 6 in which Figs. 1 to 5 show graphs of percentage detergency agent soap to anionic surfactant ratio for a variety of standard soil samples. Fig. 6 shows a plot of CIE whiteness against soap to non-soap surfactant ratio.

The test formulations of Figs. 1 to 6 comprised the folowing percentages of active ingredients.

It is to be understood that the formulations described above are by way of illustration only. Many modifications and variations are possible.

Claims

1. A liquid detergent composition comprising water, at least one soap and optionally one or more non-soap surfactants in an amount not exceeding 20% of the weight of the soap.

2. A liquid detergent composition as claimed in claim 1, wherein the non-soap surfactant is present in an amount not exceeding 15% of the weight of the soap.

3. A liquid detergent composition as claimed in claim 1 or claim 2, wherein the composition is substantially unstructured.

4. A liquid detergent composition as claimed in any preceding claim, wherein the soap and non-soap surfactants are substantially in solution.

5. A liquid detergent composition as claimed in any preceding claim, wherein the composition comprises from 1.0% to 47% by weight of soap.

6. A liquid detergent composition as claimed in any preceding claim, wherein the composition further comprises at least one builder.

7. A liquid detergent composition as claimed in claim 6, wherein said builder is substantially soluble.

8. A liquid detergent composition as claimed in claim 6 or claim 7, wherein the builder comprises any of the following either alone or in combination: phosphate, carbonate, carboxylate, citrate, phosphonate or silicate.

9. A liquid detergent composition as claimed in claim 8, wherein the builder system includes at least 1% phosphate.

10. A liquid detergent composition as claimed in any preceding claim, wherein the composition comprises from 1% to 30.0% wt of builder.

11. A liquid detergent composition as claimed in claim 10, wherein the composition comprises no more than 25% wt of builder.

12. A liquid detergent composition as claimed in any preceding claim, wherein the composition comprises at least one hydrotrope.

13. A liquid detergent composition as claimed in claim 12, wherein the hydrotrope may comprise any of the following either alone or in combination: alcohols, glycols, xylene sulphonate, toluene sulphonate or cummene sulphonates.

14. A detergent composition as claimed in claim 12 or claim 13, wherein the composition comprises from 0.05% to 20% by weight of hydrotrope.

15. A detergent composition as claimed in any preceding claim, wherein the composition further comprises an effective amount of a proteolytic, amylolytic or lipoltytic enzyme.

16. A detergent composition as claimed in claim 15, wherein the composition further comprises an effective stabilising system.

17. A detergent composition as claimed in any preceding claim, wherein the composition further comprises any of the following: optical brightening agent, foam boosting agent, preservative, perfume, dye or anti-redeposition agent.

18. A method of making a detergent composition as claimed in any preceding claim, said method comprising the step of producing the soap in situ by saponification of an oil or fat in the presence of builder/dispersant and hydrotrope.

19. A method of making a detergent composition comprising water, at least one soap, at least one builder or dispersant and at least one hydrotrope, said method comprising the step of producing the soap in situ by saponification of an oil or fat in the presence of the builder/dispersant and hydrotrope.

20. A method as claimed in claim 18 or claim 19, wherein the oil or fat comprises triglyceride.

21. A method as claimed in any of claims 18, 19 or 20, wherein the chain length of the oil or fat is C, « to

^C22-

22. A method as claimed in any of claims 18, 19 or 20, wherein the chain length of the oil or fat is C, . to

^C20-

23. A method as claimed in any of claims 18, 19 or 20 wherein the chain length of the oil or fat is C- _fi to

^C18'

24. A method as claimed in any of claims 18 to 23, wherein the oil or fat is unsaturated.

25. A method as claimed in any of claims 18 to 24, wherein the in situ saponification of the oil or fat involves a base.

26. A method as claimed in claim 25, wherein the base comprises at least one hydroxide of a group one metal.

27. A method as claimed in any of claims 19 to 26, wherein the composition optionally comprises one or more non-soap surfactants .

28. A method as claimed in any of claims 19 to 27, wherein the composition is substantially unstructured.

29. A method as claimed in any of claims 19 to 28, wherein the soap and non-soap surfactants are substantially in solution.

30. A method as claimed in any of claims 19 to 29, wherein the composition comprises from 0% to 40.0% by weight of the non-soap surfactants.

31. A method as claimed in any of claims 19 to 30, wherein the composition comprises from 1.0% to 47% by weight of the soap.

32. A method as claimed in any of claims 19 to 31, wherein the builder is substantially soluble.

33. A method as claimed in any of claims 19 to 32, wherein the builder comprises any of the following either alone or in combination: phosphate, carbonate, carboxylate, citrate, phosphonate or silicate.

34. A method as claimed in any of claims 20 to 33, wherein the composition comprises from 0.05% to 30.0% wt of builder.

35. A method as claimed in any of claims 20 to 34, wherein the composition comprises no more than 25% wt of builder.

36. A method as claimed in any of claims 20 to 35, wherein the hydrotrope comprises any of the following either alone or in combination: alcohols, glycols, xylene sulphonate, toluene sulphonate or cummene sulphonates.

37. A method as claimed in any of claims 19 to 36, wherein the composition comprises from 0.05% to 20% by weight of the hydrotrope.