EP0088612B1

EP0088612B1 - Detergent

Info

Publication number: EP0088612B1
Application number: EP83301188A
Authority: EP
Inventors: William Keane
Original assignee: BRIDGEMACE Ltd
Current assignee: BRIDGEMACE Ltd
Priority date: 1982-03-06
Filing date: 1983-03-04
Publication date: 1987-01-14
Also published as: DE3369157D1; ATE24931T1; GB2116994B; GB8305884D0; GB2116994A; EP0088612A1

Abstract

This invention relates to detergent particularly but not exclusively for use in domestic dishwashing. The detergent is a mobile liquid comprising not more than 6% water and not less than 90% of active detergent including an anionic surface active agent, coconut oil ethanolamide and a non-ionic polyether. The detergent is self thickening when diluted to 7% to 50% aqueous solutions.

Description

This invention relates to detergent particularly but not exclusively for use in domestic dishwashing although it may find industrial or alternative domestic applications.
European Patent Specifications Nos. 34393 and 34039 disclose detergents which contain in excess of 20% water.
Percentage compositions used in this specification are by weight unless indicated otherwise.
According to the present invention a mobile liquid detergent comprising not more than 8% water and not less than 90% of active detergents including an anionic surface active agent, an ethanolamide derivative of coconut oil and a non-ionic polyether, wherein a 0.01 % w/w solution of the active detergent exhibits a surface tension at 20°C of not more than 4.5x 10-² Nm-² (45 dyne cm-1) characterised in that the said mobile liquid detergent contains a total of not less than 50% of the ethanolamide derivative of coconut oil and the non-ionic polyether, and in that the liquid detergent may be diluted to form an aqueous solution having a strength in the range 7 to 50% by weight, which has a viscosity not less than 2× 10^-4m²s^-1 (200 centistokes) in the absence of an inorganic thickening agent.
The viscosities are determined at 20°C.
An active detergent is a surface active agent, an 0.01 % aqueous solution of which exhibits a surface tension at 20°C of not more than 4.5×10^-2Nm^-1 (45 dyne/cm).
Preferred detergents in accordance with this invention comprise not less than 92% active detergent, not more than 1% polyethylene glycol and not more than 4% glycerine.
Detergents in accordance with this invention have an advantage that they do not contain a large proportion of water, thereby facilitating economical transportion and packing. Furthermore, use of inactive thickening agents such as sodium chloride in compositions which have been diluted for use is unnecessary since detergents in accordance with this invention thicken upon dilution with water alone.
A preferred high foaming composition may be diluted to a 15% to 45% aqueous solution having a viscosity not less than 2x10-4m2s-1 (200 centistokes) and being capable of passing a dishwashing and foam test as hereinafter defined.
The non-ionic polyether may comprise an alkylphenyl polyether or a polyether derivative of an alcohol. Preferred alcohol polyethers may be derived from C₁₃/C₁₅ or C₁₇/C₁₈ aliphatic alcohols or from mixtures of oleyl and cetyl alcohols.
Especially preferred compositions may be diluted to 8% to 10% of their strength to produce solutions preferably having viscosities of 5×10^-4 to 10×10^-4m²s^-1 (500 to 1000 centistokes), but solutions showing viscosities up to 20×10^-4m²s^-1 (2000 centistokes) may also be obtained.
The dishwashing and foam test is performed as follows. Sodium chloride (2.5%), gelatine (2.5%), caramel (5%), instant potato (9.5%), fat (Trex or Tesco (Registered Trade Mark) lard 68%), and water (12.5%) are warmed and mixed together. The mixture is placed in a refrigerator for 24 hours and is removed from the refrigerator at least 30 minutes before use. A portion (5 g) of the mixture is applied to the surface of each plate used in the test and the plates are then left to stand for 1 hour. The plates are 23 cm in diameter and are white in colour.
A portion (0.5 g) of the detergent solution is placed in one end of a polyethylene bowl having internal dimensions of 33 cmx29 cm and a depth of 13 cm and which is inclined at an angle of 25° to the horizontal. Water (5 1) at a temperature of 54°C is allowed to run onto the detergent through an aperture 6 mm in diameter located 40 cm above the detergent. The bowl is arranged horizontally when half of the water has been added and the remaining water is allowed to pour into the opposite end of the bowl thereby providing a good foam covering the entire water surface. A second bowl is filled with water for rinsing the plates. Two soiled plates are immersed into the water and a stopclock is immediately started. After 20 seconds the first plate is washed and rinsed. A third plate is then immersed below the second plate and the second plate is then washed. A fourth plate is then immersed below the third and the process is repeated until there is no foam remaining on the surface of the water. The final temperature of the water must not be less than 45°C. The test is repeated ten times and the mean taken.
The detergent passes this test if eight or more plates can be washed before the foam dissipates when using a diluted solution equivalent to a maximum concentration of 0.01 % of the concentrated detergent.
The ethanolamide derivative of coconut oil may be a monoethanolamide or diethanolamide derivative. These may be formed by reacting coconut oil or the methyl ester thereof with either monoethanolamine or diethanolamine in the presence of sodium methoxide. The major constituent of coconut oil is the triglyceride of dodecanoic acid although shorter and longer chain triglycerides are also present.
Preferably the anionic detergent is a salt of dodecylbenzenesulphonic acid or a mixture of salts of alkylbenzenesulphonic acids of which a major constituent is dodecylbenzenesulphonic acid. Suitable mixtures may be either broad cut or narrow cut, that is there may be greater or lesser variation in the lengths of the alkyl chains. Narrow cut mixtures are preferred. The dodecylbenzenesulphonate is soft. There should be no propylene tetramer present.
Alternatively or in addition the anionic detergent may comprise an alkyl sulphate, or an alkyl ether sulphate. These sulphates are advantageous for production of detergents with good foaming properties. Alkyl sulphates may be derived from linear alk-1-ene having 12 to 18 carbon atoms for example sodium lauryl sulphate. Preferred alcohol sulphates may be derived from products of the OXO or Ziegler processes. Preferred ether sulphates are derived from ethylene oxide and may comprise a major proportion having the general formula:-
wherein n is 13 or 15, m is 2 or 3 and X is Na, K, NH₄ or an ethanolamine.
Preferred detergents in accordance with the invention incorporate an alkylphenyl polyether such as OH terminated polyether. The latter may be formed by reacting an alkyl phenol with ethylene oxide. Preferred polyethers incorporate nonyl or octyl alkyl chains or mixtures including major proportions of such chains. Preferred polyethers may comprise mixtures of polyether chains with major proportions of chains having 6 or 9 (CH₂CH₂0) units or, more preferably, major proportions of both 6 and 9 (CH₂CH₂0) unit containing chains. A greater proportion of chains having 6 (CH₂CH₂0) units to chains having 9 (CH₂CH₂0) units is particularly preferred. Smaller proportions of polyethers with larger ether chain lengths may be incorporated for example having 12 (CH₂CH₂0) units.
Preferred detergents in accordance with this invention incorporate a base. Preferred bases include monoethanolamine, diethanolamine, triethanolamine or potassium or sodium hydroxides. Monoethanolamine and triethanolamine are particularly preferred.
Detergents in accordance with this invention may be selected from a wide range of compositions in which the proportions of the ingredients are chosen so that they may be diluted to form an aqueous solution having a strength in the range 7 to 50% by weight, which has a viscosity of at least 2x10-4m2s-' (200 centistokes) in the absence of an inorganic thickening agent, and which has adequate cleaning properties in accordance with the plate washing test.
The cleaning capabilities and foam end point of detergents in accordance with this invention are dependent on a number of factors.
The ratio of anionic detergent to nonionic detergent is important, an excess of nonionic detergent being essential.
The ratio of anionic detergent to insoluble polyethers is also important, a greater proportion of anionic detergent having been found to increase the solubility of the polyether constituent.
Preferably the detergent composition of this invention incorporates not more than 30% of anionic detergent estimated as the free acid. More preferably there is between 15% and 25% of dodecylbenzenesulphonic acid present in detergents which do not contain alkyl or ether sulphates. If the latter compounds are present the preferred proportion of dodecylbenzenesulphonic acid is 8% to 25%. The proportion of alkyl or ether sulphate is preferably 10% to 30% based on the weight of the commercially available solutions, the latter containing approximately 70% of the pure compounds.
The proportion of the ethanolamide derivative of coconut oil has an important effect of the viscosity of the detergent. The derivative also serves to stabilise the foam. Preferably there is 10% to 40% of coconut oil ethanolamide present. More preferably there is 15% to 33% of the ethanolamide, a range of 20% to 30% being especially preferred.
It has been found that incorporation of alkylphenyl polyethers having a side chain incorporating a small number of (CH₂CH₂0) groups is a key factor effecting the viscosity of detergents in accordance with the invention. However, such polyethers alone may be insoluble in water. Preferably the cloud point of the insoluble polyether is less than zero. Mixtures incorporating nonylphenyl polyether are particularly preferred ingredients, a wide range of ether chain lengths being advantageous.
Optimum cleansing capacity has been achieved with alkylphenyl polyethers incorporating six or nine (CH₂CH₂0) groups of mixtures thereof. Nonylphenyl polyethers are particularly efficacious in control of the viscosity of the diluted detergent. Nonylphenyl polyethers having a low solubility in water, notably those comprising six (CH₂CH₂0) groups are particularly preferred as a major proportion of total polyethers in the detergent. Preferred detergent compositions of this invention incorporate between 25% and 55% of nonylphenyl polyether. More preferably there is between 40% and 55% of the polyether. Detergent compositions of this invention often incorporate a blend of nonylphenyl polyethers. For example a detergent which can be diluted to from 8-20% solutions having a viscosity not less than 0.3 Pa . s (300 cp) may comprise 1―5% of nonylphenyl polyether incorporating 12 (CH₂CH₂O) units, 25―45% of nonylphenyl polyether incorporating 6 (CH₂CH₂0) units and 2-10% of nonylphenyl polyethers having 8 or 9 (CH₂CH₂0) units. The actual percentages of these three components are chosen so that the total percentage of polyether falls within the aforementioned range of 25-55%. A particular efficacious range for the three aforementioned polyethers is 1-3% with 12 (CH₂CH₂0) units, 30-45% with 6 (CH₂CH₂0) units and 5-10% with 8 or 9 (CH₂CH₂0) units.
Bases having a low molecular weight are preferred, monoethanolamine having been found to provide more viscous detergents than diethanolamine. Use of triethanolamine has the advantage of maintaining a constant pH in the detergent. Ethanolamines may be used in conjunction with sodium or potassium hydroxides, the ratio of alkali metal hydroxide to ethanolamine being important.
Preferably the amount of mono-, di- and triethanolamine present is approximately 1.01.5× the stoichiometric amount based on the sulphonate and sulphate present being desirable. The amount of mono, di- or triethanolamine is preferably selected so that a 10% aqueous solution of the detergent has a pH of 6.8 to 9, more preferably of 7.5 to 8.5. A relatively larger proportion of diethanolamine or triethanolamine is required if this reagent is used in place of ethanolamine since the mono derivative is the most active.
Detergent in accordance with this invention may be diluted to form aqueous solutions of more than 7% strength, for example 8%, 10%, 20%, 25% and 40%.
The typical viscosities of various solutions are set out below:-
A particular preferred detergent comprises ingredients not exceeding a total of 100% and comprising, 7% to 30% of dodecylbenzenesulphonic acid, 10% to 30% of a solution equivalent to a 70% solution of anionic detergent of the formula:
wherein n is 13 or 15 and m is 3; X is Na or NH₄ or an ethanolamine, 25% to 50% of nonylphenyl polyether; 5% to 40% of coconut oil diethanolamide and residual percentages of ethanolamine and triethanolamine.
More preferably the detergent may comprise: 7% to 15% of dodecylbenzenesulphonic acid; 15% to 25% of the said solution of anionic detergent; 30% to 45% of nonylphenyl polyether; 20% to 35% of coconut oil diethanolamide; 1% to 4% of ethanolamine and 2% to 5% of triethanolamine.
The total percentage of nonylphenyl polyether and coconut oil diethanolamide is preferably 50% to 65%. The total percentage of dodecylbenzenesulphonic acid and the said anionic detergent is preferably 20% to 35%. The percentage of coconut oil diethanolamide is preferably 15% to 35%. This detergent yields self-thickening 10-25% aqueous solutions. Such detergents having a total percentage of polyether and coconut oil diethanolamide less than 50% form self thickening 15% to 45% aqueous solutions.
The invention is further described by means of the following Examples and with reference to Table 2 and Figures 1 to 6 of the accompanying drawings which illustrate detergent formulations in accordance with the invention.
Table 2 shows the compositions and properties of preferred detergents including the viscosities of 7%, 8%, 10% and 20% aqueous solutions;

Fig. 1 shows a 3 dimensional representation of detergent compositions in accordance with the invention;
Fig. 2 is a plan view of the diagram shown in Figure 1;
Figs. 3 to 6 show sections taken through the diagram shown in Figures 1 and 2.

In the following examples, and in Table 2, viscosity is expressed in centistokes (cs) 1 cs=10^-6m²s^-1.

Example 1

A detergent was prepared from a nonylphenyl polyether incorporating six (CH₂CH₂0) units in the side chain (36%), dodecylbenzenesulphonic acid (30%) monoethanolamine (9%), coconut oil diethanolamide (25%). A 72% aqueous solution of the detergent had a viscosity of 300 cs an 8% solution was found to have a viscosity of 1000 cs and a 10% solution was found to be thixotropic and to have a viscosity of 2000 cs on a Ford Cup No. 4. 5 gm of the 10% solution was found to clean 9 plates according to the plate test.

Example 2

A detergent was prepared from nonylphenyl polyether incorporating six (CH₂CH₂0) units (18%), dodecylbenzenesulphonic acid (20%) monoethanolamine (7%), coconut oil diethanolamide (37%) and nonylphenyl polyether incorporating 9 (CH₂CH₂0) units (18%). An 8% aqueous solution of the detergent was found to have a viscosity of 210 cs and a 10% solution was found to have a viscosity of 2000 cs 5 g of the 10% solution was found to clean 12 plates.

Example 3

A detergent was prepared from nonylphenyl polyether containing six (CH₂CH₂0) units (20%) dodecylbenzenesulphonic acid (20%), monoethanolamide (7%), coconut oil diethanolamide (33%) and nonylphenyl polyether containing nine (CH₂CH₂0) units (20%). An 8% aqueous solution of the detergent was found to have a viscosity of 200 cs and a 10% solution was found to have a viscosity of 2000 cs. The detergent (5 g of 10% solution) was found to clean 13 plates.

Example 4

A detergent was prepared from coconut oil diethanolamide (33%) nonylphenylpolyether containing 9 (CH₂CH₂0) units (5%), nonylphenylpolyether containing 6 (CH₂CH₂0) units (35%), dodecylbenzenesulphonic acid (21 %) and monoethanolamine (6%). A (10%) aqueous solution of the detergent was found to have a viscosity of 1600 cs and 7% aqueous solution was found to have a viscosity of 700 cs. The detergent (5 g of 10% solution was found to clean 10 plates).

Example 5

A detergent was prepared from coconut oil diethanolamide (32.8%) nonylphenylpolyether containing 9 (CH₂CH₂0) groups (10.8%), nonylphenylpolyether containing 6 (CH₂CH₂0) groups (29.5%), narrow cut dodecylbenzenesulphonic acid (20.9%) and monoethanolamine (5.9%).

Example 6

A detergent was prepared from coconut oil diethanolamide (25.94%), nonylphenylpolyether containing 12 (CH₂CH₂0) groups (0.89%), nonylphenylpolyether containing 8 (CH₂CH₂0) groups (4.47%), nonylphenylpolyether containing 6 (CH₂CH₂0) groups (30.41 %), a sodium sulphated C₁₃/C₁₅ alcohol with 3 (CH₂CH₂0) groups (Synperonic 3S70 a 70% commercial solution manufactured by ICI, 24.15%), dodecylbenzenesulphonic acid (8.68%), monoethanolamine (0.54%), triethanolamine (4.47%) and preservative (0.45%; Ketrol T, Cochrane and Keane Chemicals).
The resultant detergent yielded viscous, high foaming solutions upon dilution to a strength of 10%, 15% or 20%.

Example 7

A detergent was prepared from coconut oil diethanolamide (20%), nonylphenylpolyether containing 9 (CH₂CH₂0) groups (2%), nonylphenylpolyether containing 6 (CH₂CH₂0) groups (43%), Synperonic 3S70 (20%), dodecylbenzenesulphonic acid (10%), monoethanolamine (1%) and triethanolamine (4%). The resultant detergent yielded viscous detergents upon dilution to a strength of 9% to 10%.

Example 8

A detergent was prepared from coconut oil diethanolamide (25%), nonylphenylpolyether containing 6 (CH₂CH₂0) groups (25%), Synperonic 3S70 (20%), dodecylbenzenesulphonic acid (20%), monoethanolamine (2%) and triethanolamine (8%).
The resultant detergent produced viscous detergents when diluted to strengths of 15%, 20%, 25%, 30% and 40%.
A number of abbreviations are used in the following description and in Table 2 and Figures to which the description relates. These are set out below:-

diethanolamine derivative of coconut oil=CD
nonylphenylpolyether containing six (CH₂CH₂0) units=N6
nonylphenylpolyether containing 9 (CH₂CH₂0) units=N9
nonylphenylpolyether containing twelve (CH₂CH₂0) units=N12
dodecylbenzenesulphonic acid="a_cid"
monoethanolamine=MEO

Table 2 shows the composition and properties of preferred detergents. The compositions of the detergents indicated by the reference numbers 18, 20, 26, 28 and 29 may be determined from Figure 6. Figure 1 is a three-dimensional diagram showing the proportions of N6, N9, CD and dodecylbenzenesulphonic acid which may be present in detergents in accordance with the invention. Figure 2 is a plan view of the latter diagram. Figures 3 to 6 are sections through the diagram shown in Figures 1 and 2 showing variation of the ingredients N6, N9 and CD at constant proportions of dodecylbenzenesulphonic acid.
Figure 3 illustrates the variation at D of Figure 2 of a total of 40% of N9, N6 and CD in detergents containing constant proportions of 40% Acid, 11 % MEO and 9% CD. The shaded area shows the preferred compositions.
Figure 4 shows the variation at B of Figure 2 of a total of 60% of N9, N6 and CD in detergents containing constant proportions of 30% Acid, 9% MEO and 1 % CD. The shaded area shows preferred compositions.
Figure 5 shows the variations at A of Figure 2 of a total of 70% of N9, N6 and CD in detergents containing constant properties of 20% Acid, 7% MEO and 3% CD. The first shaded area shows preferred compositions including diethanolamide prepared from coconut oil or from the methyl ester thereof. The second shaded area shows additional preferred compositions including diethanolamide prepared from coconut oil only.
Figure 6 is a section of Figure 2 taken close to Figure 6 and showing variation of a total of 70% of N6, N9 and CD, in compositions containing constant proportions of 21 % Acid, 6% MEO and 3% of CD. The two shaded areas show preferred and especially preferred compositions.
Detergents including 65% or more of dodecylbenzenesulphonic acid have been found to form gels or to be unstable. Detergents comprising less than 17% of the acid have been found to have poor cleaning capacity and to exhibit low foam stability. Compositions containing 10-25% of ether sulphate need only contain 8% to 15% of the acid.
The ingredients NP6, NP9 and NP12 are manufactured under the Registered Trade Mark Synperonic by ICI although alternative brands may also be used. Coconut oil derivatives which are useful in accordance with the invention may be obtained under the Registered Trade Mark Ethylan, manufactured by Diamond Shamrock Process Chemicals Limited. Coconut oil may also be obtained from Rewo Chemicals Limited and Baxenden Chemicals Limited. Dodecylbenzenesulphonic acid may be obtained from Shell, BP, CFC or Henkel. Ethanolamine should preferably be the last ingredient which is added when making detergents in accordance with this invention.

Claims

1. A mobile liquid detergent comprising not more than 8% by weight water and not less than 90% by weight of active detergent including an anionic surface active agent, an ethanolamide derivative of coconut oil and a non-ionic polyether, (wherein a 0.01% w/w solution of the active detergent exhibits a surface tension at 20°C of not more than 4.5x10-^ZNm-² (45 dyne cm-¹) characterised in that the said mobile liquid detergent contains a total of not less than 50% by weight of the ethanolamide derivative of coconut oil and the non-ionic polyether, and in that the liquid detergent may be diluted to form an aqueous solution having a strength in the range 7 to 50% by weight, which has a viscosity not less than 2×10^-4m²s^-1 (200 centistokes) in the absence of an inorganic thickening agent.

2. A detergent as claimed in claim 1, characterised in comprising not less than 92% of active detergent, not more than 1% polyethylene glycol and not more than 4% glycerine.

3. A detergent as claimed in claim 1, characterised in that 8% to 10% aqueous solutions have a viscosity of from 5×10^-4 to 10×10^-4m²s^-1 (500 to 1000 centistokes).

4. A detergent as claimed in claim 1 characterised in that 15% to 45% aqueous solutions have a viscosity not less than 2x 10-⁴m²s-¹ (200 centistokes).

5. A detergent as claimed in any preceding claim characterised in comprising a polyether selected from an alkylphenyl polyether or a polyether derived from aliphatic alcohol selected from: alcohols having 13 to 15 carbon atoms; alcohols having 17 or 18 carbon atoms or a mixture of oleyl and cetyl alcohols.

6. A detergent as claimed in any preceding claim characterised in that the anionic surface active agent comprises dodecylbenzenesulphonic acid or a salt thereof.

7. A detergent as claimed in any preceding claim, characterised in comprising an anionic surface active agent selected from an alkyl sulphate or an anionic surface active agent represented by the formula:

wherein n is 12 or 15, m is 2 or 3 and X is Na, K, NH₄ or an ethanolamine.

8. A detergent as claimed in any of claims 5 to 7 characterised in comprising a polyether represented by the formula:

wherein r and s are integers.

9. A detergent as claimed in claim 8 characterised in that r is 8 or 9 and s is 6 to 12.

10. A detergent as claimed in claim 9 characterised in that a major proportion of the polyethers have r equal to 8 or 9 and s equal to 6 or 9 and comprise a greater proportion of polyethers having s=6 than having s=9.

11. A detergent as claimed in any preceding claim, characterised in comprising a greater percentage of anionic surface active agent than polyether.

12. A detergent as claimed in any of claims 1 to 6, or claim 11 when not appendent on claims 7 to 10 characterised in comprising 15% to 25% of dodecylbenzenesulphonic acid.

13. A detergent as claimed in any of claims 7 to 10 characterised in comprising 8% to 25% of dodecylbenzenesulphonic acid and an amount equivalent to 10% to 30% of a 70% solution of an alkyl or ether sulphate.

14. A detergent as claimed in any preceding claim, characterised in comprising 15% to 33% of said ethanolamide.

15. A detergent as claimed in claim 8 characterised in comprising 1 % to 5% of polyether wherein r is 9 and s is 12, 25% to 45% of polyether wherein r is 9 and s is 6 and 2% to 10% of polyether wherein r is 9 and s is 8 or 9.

16. A detergent as claimed in claim 15 characterised in comprising 1 % to 3% of polyether wherein r is 9 and s is 12,30% to 45% of polyether wherein r is 9 and s is 6 and 5% to 10% of polyether wherein r is 9 and s is 8 or 9.

17. A detergent as claimed in any preceding claim characterised in comprising ingredients selected from: 7% to 30% of a solution equivalent to a 70% solution of an anionic surface active agent of the formula:

wherein n is 13 or 15, m is 3, X is Na, NH₄or an ethanolamine, 25% to 50% of nonylphenyl polyether; 5% to 40% of coconut oil diethanolamide and residual proportions of ethanolamine and triethanolamine.

18. A detergent as claimed in claim 17 characterised in comprising ingredients selected from: 7% to 15% of dodecylbenzenesulphonic acid; 15% to 25% of the said solution of anionic detergent; 30% to 45% of nonylphenyl polyether; 20% to 35% of coconut oil diethanolamide; 1 % to 4% of ethanolamine, and 2% to 5% of triethanolamine.

19. A detergent as claimed in claim 17 or 18, characterised in comprising a total of 50% to 65% of nonylphenyl polyether and coconut oil diethanolamide.

20. A detergent as claimed in any of claims 18 or 19 characterised in comprising a total of 20% to 35% of dodecylbenzenesulphonic acid and the said anionic detergent.