GB2047264A

GB2047264A - Detergent compositions having a low phosphorus content

Info

Publication number: GB2047264A
Application number: GB8008923A
Authority: GB
Original assignee: Mira Lanza SpA
Current assignee: Mira Lanza SpA
Priority date: 1979-03-23
Filing date: 1980-03-17
Publication date: 1980-11-26
Also published as: CA1138294A; AR222072A1; JPS568500A; FR2451940A1; DE3010590A1; IE800313L; BE882316A; NO800843L; GR67212B; SE8002189L; BR8001652A; IT7912524A0; IT1124027B; LU82283A1; DK122880A; PT70983A; FI800526A; NL8001680A

Abstract

A detergent composition comprising, as a hardness ion complexing agent, from 10% to 50% by weight of a water soluble salt of citric acid; from 5% to 60% by weight of a water soluble salt of a fatty acid having a chain length of from 6 to 24 carbon atoms; and a phosphorus content from 0% to 2.5% by weight all based upon the total weight of the composition. To the said composition additives may be added including bleaching agents, optical brighteners, builders, alkalinity-imparting agents, surface-active agents and fillers as well as other ingredients conventionally used in detergent compositions.

Description

SPECIFICATION Detergent composition The present invention relates to dried, finely divided detergent compositions, and more particularly to those powdery detergent compositions for use either when washing by hand or in an automatic washing machine for laundering or washing any type of fabric.

It is known that in order to achieve a satisfactory degree of efficiency, a detergent composition must be formed from at least: (a) one or more surface active agents; (b) one or more hardness ion removal agents, in order to reduce the hardness of the washing water; (c) one or more alkalinity imparting agents; and (d) one or more optical brighteners or chemical bleaching agents, in order to increase the whiteness of the fibers treated with them.

The composition is generally completed by additives which are present in small amounts and exert various supporting actions, as well as by inert filiers.

The hardness ion sequestering agents are commonly termed "builders", and are further responsible for various desirable actions, exerted concurrently with their sequestering action such as peptizing action, dispersing and anti-redeposition action.

The substances which today perform these functions in the most satisfactory manner are the polyphosphates. A crucial action has been attributed to the polyphosphates in promoting an uncontrolled propagation of seaweed under particular conditions within surface waters (eutrophication factor), which leads to an adverse effect resulting from the alteration in the environmental conditions with consequent lowering of the oxygen content of the waters, due to fermentation processes connected with the final stage of the life cycle of the seaweeds. The lowering of the oxygen content of the waters also adversely affects the life cycle of the aquatic fauna.

In detergents, the replacement of polyphosphates is not an easy matter, since at present no other substances are available which are entirely harmless from the viewpoint of environmental pollution and which possess the numerous requirements which are typical of a good builder.

Quite surprisingly, it has now been found that it is possible to substantially reduce or even to eliminate the polyphosphate content of detergent compositions, without affecting their washing efficiency, by partially or totally replacing the polyphosphates in the detergent composition by a synergistic combination of a soap and a water soluble salt of citric acid.

According to a main aspect, the detergent compositions according to the present invention are characterized in that they contain from 10% to 50% of a water soluble, preferably an alkali metal, salt of citric acid, and from 5% to 60% of a water soluble, preferably an alkali metal, salt or a natural or synthetic fatty acid having a chain length of from 6 to 24 carbon atoms.

The alkali metal fatty acid salts are commonly designated as "soaps", and they will be so designated hereinafter.

It is essential that the two aforementioned compounds be simultaneously present in a detergent composition, since neither of them individually has the power of performing the action of a builder, as required if a substantial reduction in or a complete replacement of the polyphosphates is desired in the detergent compositions.

The synergistic action of the citrate and of the soap used according to the invention is best shown when washing at high temperatures, where the diminished complexing power of the citrate is compensated for by the reduced hardening action of the soap causing the precipitation of the hardness ions present in the water in the form of water-insoluble soaps. The precipitate thus formed within the washing solution has no significant tendency to stick to a washing machine or to fabrics washed therein.

The detergent compositions according to the present invention are further-more characterized by a P content ranging between 0% and 2.5% by weight of the final detergent composition, which is significantly reduced content when compared to ordinary detergents used for the washing of fabrics, in which the P content generally has a much higher value, in the range of 6 to 8% or more. The detergent compositions according to the present invention are therefore provided with a low eutrophication power, since the percentage of P is at a low or at a zero value. The citrate which is present in these compositions has a very low toxicity toward any seaweeds, invertebrates, fishes and mammals.

Moreover, it has a good biological degradability both in water and in the earth, both under aerobic and anaerobic conditions. The soap too has a very low level of toxicity, and it can be wholly degraded into CO2 and water in a very quick manner. Therefore the pollution power of the citrate and the soap is a particularly low one;while the degree of their ecological consistency appears to be high.

Various surface-active agents, alkalizing agents, supporting agents, stain removing agents, bleaching agents, optical brighteners, anti-redeposition agents and inert fillers may be added to the composition according to the invention. The said agents are well known in the art, and will not be described further.

In the composition according to the invention also other sequestering agents different from polyphosphates and citrate might also be used, in order to achieve some additional purpose of the detergents, in addition to those already quite satisfactory, which can be obtained with the detergents according to the invention.

Among the several sequestering agents which can be used in the composition according to the invention, the following organic acids, and their salts, may be mentioned: poly-carboxylic acids (other than citric acid): hydroxyiic acids, amino-carboxylic acids, carboxylic-alkylethers; carboxylic- and phosphonic acids (with a maximum P value of 2.5% in weight/calculated on the total weight of the composition); and polyanionic polymers.

As an example of inorganic type agents developing a complexing action, the compounds corresponding to the general formula (Cat2nO)xBMe203 (SiO2)y may be mentioned, where Cat is a cation of the valence n, exchangeable for calcium, x is a number from 0.7 to 1.5, Me is aluminium or boron, and y is a number from 0.8 to 6.

The composition according to the invention can be prepared by any process which is suitable for the production of powdery detergents.

These compositions are preferably prepared by a process by which the alkali metal salt of citric acid, the soap and the other components of the composition, which are stable under heat conditions, in the form of aqueous pulpy batches are transformed by hot drying, preferably by hot atomization, into easy to handle powders, particularly into beads. To the thus obtained powdered composition it is possible to add some components, such as perborates, enzymes, perfumes and the like components that cannot be subjected to the heat-drying process.

The detergent compositions of the present invention do not present the problems which are peculiar to those compositions with a low, or no content of polyphosphates.

One of these problems is the tendency to form incrustations on the metallic parts of a washing machine, and particularly on the tank or on the drum of the washing machines, or on the movable parts of the pump and of the discharge valve, on the pressure switch, and especially on the heating elements of the said machines. Particularly in the case of incrustations on the heating elements several adverse effects might occur. At first, the thus formed incrustation tends to reduce the heat exchange between the heating elements and the washing water bath. This entails the risk of an undue increase in the temperature of the heating elements, so that the heating elements will probably have a shorter average life. Moreover, the washing cycle will last for a longer time, if switching from one to the next step of the cycle is controlled by a thermostat.As a result, not only a waste of time will result, but also a waste of energy. In the case in which switching from one to the next step of the cycle is controlled by a timer, the result will be that a temperature lower than that required will be attained in the particular washing step.

This will produce, according to statistical data, a lowering of the washing efficiency.

All the above factors have an adverse influence on the average life of the washing machine.

Another problem connected with detergents having a low, or even no content of polyphosphates, is that of the loading of the fabrics, due to the deposition of salts on the washed fabrics. The fabrics might therefore become greyish and rougher to the touch, and these factors are both of fundamental importance to the standard of the washing.

The average life of the fabrics is also adversely affected.

Finally, the problem which probably is the most important in detergent compositions with a low, or even no content of polyphosphates is that of the washing performance of the detergent.

The users are presently accustomed to employ high standad detergents which permit one to obtain quite satisfactory results. This is due to the significant contribution of polyphosphates which occur in the presently used detergents.

The detergents of the present invention enable a good standard to be maintained in the washing of fabrics, and to keep undamaged, in the mechanical washing, the components of a washing machine.

By the use of the detergents according to the invention, the incrustat;ons on the machine drum, on the tank surfaces and on the heating elements are eliminated or reduced to a minimum, whilst incrustations on the washed fabrics, are very much reduced, with a good efficiency of detergency. Therefore the compositions according to the invention enable the average life of both the fabrics and the washing machines to be maintained almost unchanged.

The following specific examples illustrate the invention. In the Examples, some detergent compositions according to the invention are compared with some commercial detergents having a high phosphorus content, in order to compare their efficiency.

EXAMPLE I Composition I with 1.5% of P % by Commonly sold detergent compositions weight as found on the market Sodium citrate dihydrate 20.0 A B C Sodium soap (1) (from fatty acids of hydrogenated tallow) 15.0 of P present 7.6 7.2 6.3 Sodium dodecyl benzene sulphonate 5.0 Polycondensates of tallow alcohols with 11 moles of ethylene oxide 2.0 Sodium silicate (Na2O. 2Si02) 6.0 Sodium tripolyphosphate Carboxymethylcellulose 1.0 Sodium perborate tetrahydrate 30.0 Stilbene optical bleaching agent 0.3 Sodium sulphate Moisture

to make 100 (1) Percentage of the hydrogenated tallow fatty acids in the sodium soap used.

Oto = 0.1%, C12 = 0.3%, Cl4 = 3.1%, C1, = 0.8%, Cl6 = 38%, Cl7 = 2.7%, C18 = 54%, C20 = 1.0% The tests were made in a drum-type washing machine under the following conditions: - Detergent concentration: 7.5 g/l in water - Hardness of the water: 25 F (french degrees) - Load of laundry with natural dirt: 4.5 Kg.

washing temperature: from ambient temperature up to 900C - Number of washings: 14 The results of these tests were as follows: Dtergency: on fabrics soiled with natural dirt it appeared to be substantially the same for the composition I, according to the present invention, and for the compositions A and B; C gave significantly lower results.

Degree of whiteness: the compositions I and A appeared to be the best, according to the classification shown hereunder: Composition I 1st Composition A 1st Composition B 2nd Composition C 3rd Deposits on fabrics: assessed upon completion of 14 washings, and expressed as the total ash percentage on a fabric, with the following results: Composition I 0.32% Composition A 0.25% Composition B 0.35% Composition C 0.90% Deposits on heating elements: assessed upon completion of 14 washings and expressed as increases in weight wffh the following values: Composition I +0.6 g.

Composition A +0.8 g.

Composition B +1.3 g.

Composition C +2.5 g.

EXAMPLE IT Composition II with 0% of P % by Commonly sold detergent compositions weight as found on the market Sodium citrate dihydrate 30% D E F Sodium soap Cfrom fatty acids of hydrogenated fish oil (1) 30% Sodium dodecylbenzene sulphate 3% Polycondensate of tallow alcohols with % of P present 7.0 7.2 4.4 11 moles of ethylene oxide 3% Sodium silicate (Na2O . 2SiO2) 6% Carboxymethylcellulose 1% Sodium perborate tetrahydrate 25% Stilbene optical breaching agent 0.3% Sodium sulphate Moisture Other minor components

to make 100 (1) Percentage of hydrogenated fish fatty acids in the sodium soap used:: Cl0 = 0.5%, Cl2 = 0.4%, Ci4 = 6.2%, C15 = 1.0%, C16 = 28.7%, C17 = 1.7%, C18 = 34.1% C20 = 15.0% C22 =12.4%.

The efficiency assessments have been made under the same conditions as in example The following results were obtained: Detergency: no significant differences between the four examined detergents were noted.

Degree of whiteness: Composition F 1st Composition II 2nd Composition D 2nd Composition E 2nd Deposits on fabrics: Composition II 0.11% Composition D 0.28% Composition E 0.23% Composition F 0. 16% Deposits on heating elements: Composition II 0.5 g Composition D 1.5 g Composition E 1.2 g Composition F 0.9 g EXAMPLE III Composition Ill with 0% of P % by Commonly sold detergent compositions weight as found on the market Sodium citrate dihydrate 10% A F Sodium soap (from fatty acids of non-hydrogenated tallow (1) 20% Sodium dodocylbenzene sulphonate 2% % of P present 7.6 7.4 Polycondensate of tallow alcohols with 11 moles of ethylene oxide 5% Sodium silicate (Na20.2SiO2) 6% Carboxymethyl cellulose 1% Sodium perborate tetrahydrate 27% Stilbene optical bleaching agent 0.25% Proteolytic enzyme 1.0% Sodium sulphate Moisture

to make 100 (1) Percentage of non-hydrogenated tallow fatty acids in the sodium soap used (the asterisks placed beside the numbers, such as: C18***, indicate the presence and number of unsaturated double bonds).

Clo = 0.1%, C12 = 0.6%, C14 = 3.3%, C15 = 1.2%, C16 = 18.8%, C16* = 4.8%, C17 = 1.6%, C18 = 8.8%, C18* = 51.1%, C18** = 7.1%, C20 = 0.4%, C20* = 1.5%, C22 = 0.4% The detergents A and F are the same as for Examples I and II.

Also, in this instance, the methods and the conditions of assessment are similar to those described in Example I.

Detergency: no significant differences in efficiency have been noted.

Degree of whiteness: Composition III 1 sot A 1st F 1st Deposits on fabrics: Composition Ill 0.25% A 0.25% F 0.16% Deposits on the heating elements: Composition lil 0.8 g A 0.8 g F 0.9 g Also a series of 50 consecutive washings was carried out with the compositions of Examples I, li, III in order to discover any damage possibly caused to the mechanism of the washing machines. This was found to be no worse than that encountered with the commonly available detergents A, C, and F, already mentioned in connection with the examples.

The preceding specific embodiments are merely illustrative of the invention. It is to be understood however that the expedients known to those skilled in the art, or disclosed herein, may be employed without departing from the'scope of the invention.

Claims

1. A dried finely divided detergent composition comprising a surface active agent, an alkalizing agent, a bleaching agent and a hardness ion complexing agent and having a total phosphorus content of from 0 to 2.5% by weight based on the total weight of the composition, characterized in that it comprises as the main hardness ions complexing agent from 10 to 50% by weight, based on the total weight of the composition, of a water soluble salt of citric acid, and from 5 to 60% by weight, based on the total weight of the composition of a water soluble salt of a fatty acid having a chain length of from 6 to 24 carbon atoms.

2. A composition according to claim 1, further characterized in that the fatty acid is a natural fatty acid.

3. A composition according to claim 1, further characterized in that the fatty acid is a synthetic fatty acid.

4. A composition according to any of the preceding claims, further characterized in that the said fatty acids have a chain length from 10 to 12 carbon atoms.

5. A composition according to any of the preceding claims, further characterized in that the salt of citric acid is an alkali metal salt of citric acid.

6. A composition according to any of the preceding claims, further characterized in that the salt of a fatty acid is an alkali metal salt of a fatty acid.

7. A composition according to any of the preceding claims, further characterised in that the salt of citric acid is present in an amount from 20 to 40% by weight, based upon the total weight of the composition.

8. A composition according to any of the preceding claims, further characterized in that the said salt of a fatty acid is present in an amount from 1 5 to 35% by weight, based upon the total weight of the composition.

9. A composition according to any of the preceding claims, further characterized in that the watersoluble salt of citric acid is tri-sodium citrate.

1 0. A composition according to any of the preceding claims, further characterized in that the water-soluble salt of a fatty acid is a sodium salt of a natural fatty acid.

11. A composition according to claim 1 or any of claims 4 to 10 as appendant to claim 1 characterized in that the fatty acids are hydrogenated fatty acids.

12. A composition according to any of the preceding claims further characterized in that said surface active agent is an anionic surface active agent.

1 3. A composition according to any of claims 1 to 11, further characterized in that said surface active agent is a non-ionic surface active agent.

14. A composition according to claims 1 to 1 further characterized in that the said surface active agent is a cationic surface active agent.

1 5. A composition according to any of claims 1 to 11, further characterized in that the said surface active agent is an amphoteric surface active agent 1 6. A dried, finely divided detergent composition according to claim 1 and substantially as hereinbefore described with reference to any one of the Examples.