Liquid detergent and/or bleaching compositions

Abstract

 Liquid detergent and/or bleaching compositions for laundry use, contain low molecular weight tertiary amine oxide. The detergents are of the non-built type.

Description

[0001] The invention relates to prevailingly liquid detergent and/or bleaching compositions, containing low molecular weight tertiary amines, for example triethanolamine; the invention relates in particular to water-based liquid laundry detergent compositions usually utilized for automatic washing machines, as are described for example in British Patent No. 2,197,340.

[0002] The water-based liquid detergents for laundry washing machines at present in commerce have compositions, which can be substantially divided into two classes:

(a) clear compositions, consisting of highly concentrated solutions of surface-active matters, which do not con­tain water softeners (builders) and consequently are defined as "non-built" compositions; these compositions exhibit a rather low viscosity (below 500 mPa.s at room tem­perature) and usually contain triethanolamine (TEA), generally as a neutralizer of the acid components and/or as a solubilizer of the surface-active compounds;

(b) opaque compositions, which contain low concentrations of surface-active components and considerable amounts of builder (for example zeolites 4A, generally present in the form of suspensions) and which are therefore defined as "built" compositions; such compositions exhibit relatively high viscosities (high­er than 1,000 mPa.s at room temperature).

[0003] Both the "built" products and the "non-built" products do not contain any stain-removing (bleaching) com­ponent and, contrary to what happens with the detergents for washing machines (in powder), they do not exhibit satisfactory stain removal activity (chemical bleach­ing) and therefore provide lower performances.

[0004] It is generally assumed that this significant inferiority of the liquid detergents as compared with the corresponding products in powder can be overcome merely by adding to the liquid, as washing begins, the usual bleaching additives based, for example, on perborate, percabonate, hypochlorite and the like, either activated or non activat­ed.

[0005] Conversely,the Applicant has surprisingly observ­ed that the same bleaching results, at the doses suggest­ed for the bleaching agents, are obtained only with the li­quid detergents of the "built" type, while with the "non-­built" products the stain-removal action of the additive, for example perborate, is negligible, so that in practice the addition of that additive is nearly useless. If one considers that the use of liquid detergents for washing machines has great possibilities of development and that the detergent compositions of the "non-built" type are the most widely utilized, the inefficiency of non-built detergents in their bleaching action (despite the addition of bleaching agents which have proved to be highly effective with other compositions) represents a serious problem.

[0006] Thus, it is an object of the present invention to allow the bleaching agents to exert their stain-removing ac­tion also in the presence of liquid detergents of the " non-­built" type and, by consequence, to permit that also with such detergents bleaching effects may be obtained when the conventional bleaching additives are added at the suggested doses. The Applicant has now succeeded in properly modifying the composition of the "non-built" liquid detergents, by el­iminating the inhibiting action exerted by the latter on the bleaching agents.

[0007] In its broadest aspect, the invention rel­ates to liquid detergent and/or bleaching com­positions containing at least a low molecular weight tertiary amine oxide, selected from the group consisting of:

a) trialkanolamine oxides, having formula:

where groups R, same or different from eachother, are straight or branched alkylene groups having from 1 to 4 C atoms;

b) trialkylamine oxides, having formula:

where groups R′, like or different from one another,are straight or branched alkyl groups having 1 to 4 C atoms; and

c) heterocyclic compounds selected from: triethylenediamine N-oxide, triethylenediamine N,N′-dioxide, N-methyl-morpholine N-oxide and N-methyl-piperidine N-oxide.

[0008] For example, if the commonly used triethanolamine (TEA) is replaced in the liquid "non-built" detergents, by the respective N-oxide (TEAO) of formula (III) :
(HO-CH₂-CH₂-)₃-N=O      (III)
and obtained bleaching levels are comparable, other conditions being equal, with what is obtained with the liquid "built" detergents and with the powder detergents; the use of said N-oxides and in particular TEAO does not involve particular technological pro­blems and it can be proportioned in the same manner as tri­ethanolamine. As TEAO does not possess the alkalinity of TEA, the neutralization of the acid components of the liquid de­tergent(fatty acids, alkylbenzenesulphonic acid etc.), which is usually carried out with TEA, can be completed, in the presence of TEAO, with NaOH or, even better, with KOH, with­out jeopardizing the solution homogeneity; the use of potash is preferred to caustic soda as it allows a higher stability of the liquid detergent compositions at lower temperatures. If amine is not fully replaced by N-oxide, the alkali amount can be advantageously reduced. The composition of the invention may thus additionally contain a low molecular weight tertiary amine.

[0009] According to the known technique, N-oxides are obtainable for example by oxidation of the corresponding tertiary amines with hydrogen peroxide. Said oxidation may occur with H₂O₂ either substoichiometric amounts or in excess.

[0010] The synthesis of N-oxides with an excess of hydrogen peroxide results, on conclusion of the reaction, in the presence of residual traces of H₂O₂, the amount thereof being dependent on the utilized excess; for example, if the H₂O₂ excess amounts to 10%, the residue obtained amounts from 0.5 to 1% by weight based on the weight of the reaction mixture. This type of synthesis is less preferred since, unless suitable modifications are made immediate evaporation of the solvent cannot be carried out due to the inherent explosion risk, and/or a direct utilization of the reaction mixture in the preparation of the liquid detergents is not possible. Overcoming those problems may cause serious technological complications in both cases.

[0011] It has been suggested to eliminate the residual H₂O₂ by MnO₂, which is considered an excellent agent for H₂O₂ decomposition but which does not cause N-oxide damage. However, the use of MnO₂ is not possible in practice. It would require careful filtration, which involves a complex operation. However even after a careful filtration, small traces of MnO₂ remain in the N-oxide and by consequence also in the detergents containing it. These residues would be able to exert their decomposition effect also on the bleaching peroxides which are added to the liquid detergents during the washing cycle thereby drastically reducing the performance of the peroxides.

[0012] Other techniques for removing excess H₂O₂, such as eg heating, are not advisable because the N-oxides, in general, decompose at temperatures higher than 60°C. Also metals (for example Fe or Cu), which are known for their degradation action on H₂O₂, are not utilizable, because they are also efficacious in causing the degradation of N-oxides and, in many aspects, are undesirable during the end use of the detergents.

[0013] The applicant has noted that if the hydrogen peroxide amount is maintained below the stoichiometric values, it is possible to obtain a practically H₂O₂-free product, immediately ready for use in the detergents formulations and/or for water evaporation, if a concentration N-oxide is desired. The thus obtained product contains low amounts of converted tertiary amine which do not impair at all the bleaching power and, on the contrary, make the detergent formulability easier. Generally, a H₂O₂ amount ranging from 70% to 99% of the stoichiometric value is recommended in the amine oxidation step.

[0014] The presence of unconverted amine furthermore balances the lower alkalinity of the corresponding N-oxide, and the consequent lower neutralizing power, with respect to the fatty acids, promotes the detergent homogeneity and reduces the amount of alkali necessary to bring the composition to a prefixed pH value.

[0015] The present description, examples included, refers in detail to the use of triethanolamine (TEA), either free or salified (for example with fatty acids or alkylbenzene sulphonic acids), at least partially converted to the cor­responding N-oxide (TEAO); the scope of the invention, how­ever, includes other types of low molecular weight tertiary amines and in particular triethylamine, triethylenediamine (PABCO), N-methylmorpholine, N-methylpiperidine etc. The replacements of the amines by the corresponding N-oxides does not adversely affect the storage stability of the de­tergent even at low temperatures, at high humidity values and over long periods.

[0016] Oxidation of tertiary amines with hydrogen peroxide can be conducted on the amines as such, on the salts thereof with fatty acids (TEA soaps) or with other acid compounds, or also on a liquid detergent which contains the amine, by adding H₂O₂ to said detergent.

[0017] The detergent composition may contain other components conventional for non-built liquid detergents. The detergents are prevailing liquids, that is they may contain suspended solids but have a continuous liquid phase.

[0018] The following examples are given for a merely il­lustrative purposes, without limiting in any way the scope of the invention.

Example 1 (test with H₂O₂ in excess)

[0019] N-oxide of triethanolamine (TEAO) was synthesised by reaction between triethanolamine and hydrogen peroxide, according to the scheme :
(HO-CH₂-CH₂)₃-N + H₂O₂→(HO-CH₂-CH₂)₃-N=O + H₂O. Into a 2-neck, 1,000 cm³ flask, equipped with a bulb cooler, 150 g of triethanolamine (TEA), 300 g of water and 150 mg of EDTA (sodium ethylenediaminetetraacetate)were poured; the mixture was heated at 55°C by means of an outer water bath, whereafter 111 g of H₂O₂ at 33.8% by weight, cor­responding to about 10% of H₂O₂ in excess, with respect to the stoichiometric value, were gradually introduced (by us­ing a dropping funnel). The addition rate was such as to maintain the temperature below 60°C; on conclusion of the addition, temperature was maintained at 55°C for 90 minutes. Residual H₂O₂ was allowed to spontaneously decompose in the course of a few days, and subsequently the product was dried by evaporation of water (in a rotary evaporator under vacuum) at a temperature not exceeding 40°C. A dry residue of about 165 g, corresponding to a practically quantitative yield, was obtained.

Example 2 (test with deficient H₂O₂)

[0020] Example 1 was repeated reducing the amount of hy­drogen peroxide (at 33.8%) to 103 g, an amount equivalent to about 98% of the stoichiometric value; the final product was analyzed for its H₂O₂ content by means of the paper method (PEROXID-TEST; MERKOQUANT 1011) and the analysis result was negative. No appreciable traces of residual H₂O₂ were found.

Example 3 (concentrated N-oxide)

[0021] In order to obtain a more concentrated TEAO, without resorting to one or more water evaporation steps, ex­ample 1 was repeated, eliminating the 300 g of water (added in example 1 as a reaction solvent) and directly re­acting TEA with H₂O₂. In particular: 111g of H₂O₂ at 33.8% by weight were added at 55°C to 150 g of TEA, whereafter the temperature was maintained at 55°C for 2 hours. An aque­ous solution at about 67% by weight of TEAO was thus obtained, this value being much higher than the N-oxide concentration obtained in example 1 (29%).

Example 4

[0022] In order to check the influence of the invention on the bleach­ing power of the liquid "non-built" detergents, when a bleach­ing agent is added to the latter, bleaching tests in a com­mercial-type washing machine REX (mod. RF 224X) were conduct­ed under the following conditions :
washing water: tap water at 16°F hardness;
washing program: at 60°C (maximum suggested temperature for liquid detergents);
laundry load: 3 kg (for each washing) of white and clean cot­ton cloth + two 10x10 cm cotton test pieces EMPA 114 supplied by EMPA Institute, standard stained with red wine;
detersive dose: 180 g for each washing (average dose recom­mended by the manufacturers);
bleaching agent dose: 40 g for each washing (average dose recommended by the manufacturers). As a bleaching agent, a commercial product (product I) based on sodium monohydrate perborate (PBS-1) and on activator (TAED = tetraacetyl ethylenediamine)was used. The composition of the bleacher was the following: PBS-1 = 47%; TAEL = 13%;
fillers and minor components = the balance to 100%.
As liquid detergents, a "built" type com­mercial product (product II), a non-built type commercial product (product III), a laboratory-reproduced formulate hav­ing a composition similar to said product III (as to the most important components,TEA included) and an analogous formul­ate, also reproduced in laboratory, in which TEA had been replaced by N-oxide (TEAO) were compared; the last two formulates are indicated in Table 1 as III/TEA and III/TEAO, respectively.

TABLE 1

Components	PRODUCT II	PRODUCT III	III/TEA	III/TEAO
Anionic surfactants	7.5%	13.7%	14.0%	14.0%
Non-ionic surfactants	2.8%	10.7%	11.0%	11.0%
Coconut fatty acids	-	13.3%	13.0%	13.0%
Zeolite 4A	25.1%	-	-	-
Ethyl alcohol	-	8.0%	10.0%	10.0%
Glycerine	7.5%	-	-	-
TEA	-	10.0%	10.0%	(10.0%)
TEAO	-	-	-	10.0%
Water and minor additives (*)	bal.to 100	bal.to 100	bal.to 100	bal.to 100

(*) bal. = balance

Formulates III and III/TEA exhibited a pH value ranging from 8 to 8.5, while formulate II had a pH value equal to about 10; formulate III/TEAO had a pH value equal to 6.8, due to the lower alkalinity of TEAO in comparison with TEA. For the purposes of the invention, the pH of formulate III/TEAO was brought to a value of 8-8.5 (namely to the value of the "non-­ built" detergents) by addition of NaOH. The addition of NaOH, in order to adjust the pH value, is a usual step in the formulation of the liquid detergents, also in the absence of TEAO, and therefore it does not affect the validity of the invention. In the washing machine tests, the following comb­inations (detergent + bleaching agents) were used :

A PRODUCT II alone

B PRODUCT II + bleaching additive

C PRODUCT III alone

D PRODUCT III + bleaching additive

E III/TEA + bleaching additive

F III/TEAO + bleaching additive.

The obtained bleaching results are reported hereinafter and express the per cent removal (D) of bleachable stain (red wine), calculated as follows :

where :

a = whiteness of the test-piece washed during the test;

b = whiteness of the test-piece prior to washing;

c = whiteness of the not stained test-piece.

Whiteness was measured by means of reflectometer Elrepho-­Zeiss, in comparison with MgO, assumed as a blank (whiteness = 100), using filter No. 6. The results are recorded on Table 2.

TABLE 2

Formulate	Removal of bleachable stains (%)
A	29.1
B	72.0
C	48.7
D	50.6
E	48.2
F	78.1

These data prove that the addition of bleaching agents to liquid detergents leads to the expected bleaching effect only in the case of "built"detergents (see cases A and B) which do not contain TEA, while it does not lead to ap­preciable effects when the liquid detergent is of the "non-­built" type (see cases C and D). Furthermore, these data prove that the substitution of TEA by TEAO, in the "non-­built"detergents, results in a marked improvement of white­ness (see cases E and F), bringing it again to the values obtainable with the built formulates.

Example 5

[0023] Further bleaching tests were carried out by adding to a non-built liquid detergent a bleaching mixture consist­ing of sodium perborate monohydrate (PBS-1) and of TAED in a practically stoichiometric ratio (about 48% of PBS-1 and about 52% of TAED). The tests were conducted in a 500 cm³ flask, adding to 250 cm³ of deionized water, brought to 60°C, 7 g of liquid detergent and 0.7 g of the bleaching mixture; finally, two 5x5 cm test-pieces of cotton EMPA 114 stained with red wine (as in ex.4) were introduced. After 1 hour, during which time the test-pieces were kept at a constant temperature of 60°C and under stirring, the test-pieces were rinsed in running water, dried, ironed and subject­ed to whiteness determination as described in example 4. As detergents, another commercial li­quid product (PRODUCT IV), a laboratory-reproduced formulate having a composition similar to PRODUCT IV in the essential com­ponents, TEA included (product IV/TEA) and a formulate like the pre­ceding one, where TEA had been replaced by TEAO (form­ulate IV/TEAO) were compared; the weight percentages of the components are indicated in Table 3.

TABLE 3

Components	PRODUCT IV	IV/TEA	IV/TEAO
Linear sodium alkylbenzenesulphonate (LAS)	11.3%	11.3%	11.3%
Sodium lauryl sulphate	3.2%	3.2%	3.2%
Alcohol (C₁₂-C₁₃), ethoxylated with 7 moles of EO	13.7%	13.7%	13.7%
Cocunut fatty acids	7.0%	7.0%	7.0%
Ethyl alcohol	9.0%	10.0%	10.0%
TEA	5.0%	5.0%	-
TEAO	-	-	5.0%
Water and minor additives	bal.to 100%	bal.to 100%	bal.to 100%

The bleaching tests were carried out using the following combinations :

A PRODUCT IV alone

B PRODUCT IV + bleaching additive

C IV/TEA + bleaching additive

D IV/TEAO + bleaching additive

The bleaching results are shown in Table 4.

TABLE 4

Formulate	Dirtiness removal (%)
A	51.2
B	52.9
C	49.5
D	80.6

These tests prove that also for a different "non-built" form­ulate (PRODUCT IV), the action of the bleaching agent is negligible if TEA is present in the detergent, while it is fully exerted when the corresponding N-oxide is present.

Example 6

[0024] Example 4 was repeated with liquid "non-built" form­ulations, additioned, at the moment of washing, with a com­mercial bleaching product (PRODUCT I) (and having a basic com­position like composition III/TEA of example 4) and with other formulations in which TEA had partially been repla­ced by TEAO, maintaining the sum TEA+TEAO constant, accord­ing to the scheme of Table 5.

TABLE 5

Formulate	Weight ratio
	(TEA : TEAO)
A	1 : 0
B	9 : 1
C	7 : 3
D	5 : 5
E	3 : 7
F	1 : 9
G	0 : 1

Where necessary, the pH of the formulates was brought to 8-­8.5 with NaOH; the bleaching results, evaluated and expressed as in example 4, are indicated in Table 6.

TABLE 6

Formulate	stain removal (%)
A + PRODUCT I	34.1
B + PRODUCT I	35.6
C + PRODUCT I	36.4
D + PRODUCT I	46.7
E + PRODUCT I	69.9
F + PRODUCT I	76.3
G + PRODUCT I	78.1

These tests show that good bleaching performances are ob­tainable even if TEA is partially replaced by TEAO; al­ready with TEAO amounts corresponding to mixture TEA/TEAO in a 30:70 ratio, the results obtained are decidedly su­perior than the ones found with TEA alone.

Example 7

[0025] Formulates A-G of example 6 were subjected to a low temperature stability test, in order to ascertain pos­sible precipitations or demixing as the inner temperature of the detergent decreases. In particular, the formulates were gradually cooled by immersing them into an ice bath, till reaching an inner temperature of +3° C, then they were maintained at such temperature for 30 minutes. The results of the visual observations are reported on Table 7.

TABLE 7

Formulate	Appearance
A	Clear, homogeneous
B	Clear, homogeneous
C	Clear, homogeneous
D	Clear, homogeneous
E	Clear, homogeneous
F	Clear, homogeneous
G	Clear, homogeneous

This proves that the use of TEAO instead of TEA does not adversely affect the storage stability of the formulates at low temperatures.

Example 8

[0026] A series of formulates containing mixtures of TEA and TEAO was prepared on the basis of the IV/TEA described in example 5, bringing all the formulates to a pH value of 8-8.5 with NaOH (where necessary) and maintain­ing the sum TEA + TEAO constant as in example 7. The deter­gents were then subjected to a low-temperature storage test, as is described in example 7, maintaining the products at +2°C for 30 minutes. The results are reported on Table 8.

TABLE 8

Formulate	TEA/TEAO ratio	Formulate appearance
A	1 : 0	Clear and homogeneous
B	8 : 2	Clear and homogeneous
C	6 : 4	Clear and homogeneous
D	4 : 6	Clear and homogeneous
E	2 : 8	Clear and homogeneous
F	0 : 1	Clear and homogeneous

Example 9

[0027] In the preparation of the liquid"non-built" formul­ates it may be sometimes preferable to utilize, as a start­ ing material, the TEA salt of the coconut fatty acids (TEA soap) instead of the fatty acids and TEA separately, as usually occurs. This does not represent, in itself, a hin­drance to the replacement of TEA by TEAO; in fact, the test described hereinafter proves that also the TEA soap reacts with H₂O₂ to provide TEAO.
Description of the test:
Into a two-neck flask having a 1,000 cm³ volume, equipped with a bulb cooler, there were charged 180 g of TEA soap (from coconut fatty acids), 500 g of H₂O and 100 mg of EDTA; the mass was brought to 55°C and 55 g of H₂O₂ at 33.8% by weight were gradually added without exceeding 60°C; the temperature was then maintained at 55°C for about 90 minutes. The oc­curred conversion of TEA to TEAO was evidenced by the fact that the solution passed from the limpid state (before re­action) to a cloudy and gelatinous state. That was due to the reduced alkalinity of TEAO in comparison with TEA and to the consequent lower neutralizing activity ex­erted on the fatty acid, which at the end of the re­action was therefore (partially) present in the water-ins­oluble free acid form.

Example 10

[0028] The conversion of TEA to TEAO can be carried out also using a liquid (TEA-containing) detergent, by adding to said detergent a suitable H₂O₂ amount. To 100 g of li­quid detergent III/TEA, described in example 4, brought to 55°C in a two-neck, 250 cm³ flask, equipped with a bulb cooler, 6.8 cm³ of H₂O₂ at 33.8% by weight were gradually added (without exceeding 60°C); after the ad­dition, the temperature was maintained at 55°C for 150 minutes, whereafter the pH of the detergent was brought to a value of 8-8.5 by means of NaOH. To ascertain that the reaction had really occurred, the detergent so treated (freed from the residual H₂O₂ traces) was utilized to car­ry out a bleaching test according to the modalities des­cribed in example 5, using as a blank a commercial deter­gent (PRODUCT III). In particular, 5.3 g of detergent, dis­solved in 250 cm³ of distilled water (at 60°C), were additioned, under stirring, with 0.7 g of a bleaching mixture, describ­ed in example 5, consisting of PBS-1 (48%) and TEAO (52%) and furthermore, immediately after, with two 5x5 cm test-­pieces of cotton EMPA 114, stained with red wine. After 60 minutes the two test-pieces were rinsed in running water, air-dried, ironed, and subjected to whiteness determination, as described in example 4; the bleaching values were as follows :

Formulate	Removed stains (%)
PRODUCT III	57.5
III/TEA + H₂O₂	80.9

These tests prove the occurred replacement of TEA by TEAO in the III/TEA detergent treated with H₂O₂

Example 11

[0029] The liquid non-built detergents containing TEAO instead of TEA can be brought to the pre-established pH value, usually 8-8.5, either with NaOH or with KOH. However, when KOH is used, the formulate acquires an even higher sta­bility at low temperatures. The following test is a proof thereof: the III/TEA composition of example 4 was brought to a pH = 8.2 with KOH and was subjected to the stability test at low temperatures described in example 8; said composition remained limpid and homogeneous up to a temperature of -1°C.

Claims

1. Liquid detergent and/or bleaching composition containing a low molecular weight tertiary amine oxide, selected from:

a) trialkanolamine oxides having the formula (I):

where groups R are the same of different and are straight or branched alkylene groups having 1 to 4 carbon atoms;

b) trialkylamine oxides having the formula (II):

where groups R′ are the same or different and are straight or branched alkyl groups having 1 to 4 carbon atoms, and

c) heterocyclic compounds selected from:
triethylenediamine N-oxide, triethylenediamine N,N′-dioxide,N-methyl-morpholine N-oxide and N-methyl-piperidine N-oxide.

2. A composition according to claim 1, in which the tertiary amine oxide is triethanolamine N-oxide of the formula:

3. A composition according to claim 1, in which the tertiary amine oxide is selected from: triethylenediamine N-oxide, triethylenediamine N,N′-dioxide, N-methyl-morpholine N-oxide, N-methyl-piperidine N-oxide and triethylamine N-oxide.

4. A composition according to any of the preceding claims, containing also NaOH or KOH, as a pH regulator.

5. The compositions according to any of the preceding claims, containing also the tertiary aine in its non-oxidized form, the ratio of amine oxide:amine ranging preferably from 70:30 to 99:1 by weight.

6. A composition according to any preceding claim which is substantially free of builder.

7. Use of a low molecular weight tertiary amine oxide as defined in claim 1 optionally in admixture with the corresponding non-oxidised tertiary amine in the preparation of a non-built liquid laundry detergent composition.

8. A process of preparing a composition according to any of claims 1 to 6, characterised in that the selected tertiary amine is converted into the corresponding N-oxide, by reaction with hydrogen peroxide, and that the resulting N-oxide is then added to the other components of the composition.

9. A process of preparing a composition according to any of claims 1 to 6, characterised in that the selected tertiary amine is added in the non-oxidised form to the other components of the composition and it is then converted "in situ" into the corresponding N-oxide by reaction with hydrogen peroxide.

10. The process according to claim 8 or 9, in which the H₂O₂ is used in a substoichiometric amount.

11. The process according to any of claims 8 to 10, characterised in that the oxidation is carried out on the corresponding tertiary amine in salified form, preferably in the form of a salt with a fatty acid or with an alkylbenzenesulphonic acid.

12. A process for forming a laundry wash liquor in which a composition according to any of claims 1 to 6 and a composition containing a bleaching agent are dissolved in water.