DE3874806T2 - DETERGENT COMPOSITION. - Google Patents

Description

This invention relates to a detergent composition, in particular a detergent composition for washing and softening fabrics.

Detergent compositions usually contain, in addition to an active detergent material for removing soil from fabrics, a detergent builder material whose function is primarily to prevent calcium ions in hard water from reducing the effectiveness of the active detergent material. For many years, phosphates such as sodium tripolyphosphate have been used as detergent builders.

For a number of reasons it has become desirable to provide detergent compositions which are free or substantially free of phosphorus. A number of alternative non-phosphorus builders have been proposed, in particular a mixture of an alkali metal carbonate such as sodium carbonate with a calcium carbonate seed such as calcite (see GB 1 437 950 - UNILEVER Case No. C720) and its compositions containing such builders, to which the present invention is directed.

The use of a sodium carbonate/calcite builder blend instead of sodium tripolyphosphate results in a number of differences, in particular a greater tendency to harden fabrics. Hardening is a phenomenon that occurs with many detergent compositions, whereby the hand of the fabric becomes hard after washing. This is particularly evident in textiles made from natural fibres such as cotton, and may be partly due to the removal of natural lubricating materials from the fibers of the tissue.

A number of materials have been suggested by the art as fabric softeners capable of reducing the degree of hardening achieved in the wash. One such class of materials are the smectite clays which have a high exchange capacity as disclosed in GB 1 400 898 (PROCTER & GAMBLE). However, it has been found that such clays are most effective when used in the presence of a peptising agent such as sodium tripolyphosphate. Such clays are, however, less effective in the absence of tripolyphosphate ions. The art has therefore not recommended clays as effective fabric softening or anti-hardening agents for use with detergent compositions in which alkali metal carbonates are used instead of tripolyphosphate salts.

It has now been found that the tissue hardening effect of compositions containing a sodium carbonate/calcite builder mixture can be overcome by the presence of a tissue softening clay material.

Therefore, according to the invention there is provided a detergent composition for washing and softening fabrics, which is substantially free of phosphate builders and comprises:

(i) 2 to 40% by weight of at least one non-soap active detergent ingredient;

(ii) 5 to 40% by weight of a builder material containing a water-soluble carbonate in an amount that is at least 5% by weight of the composition;

(iii) 10 to 60% by weight of a water-insoluble carbonate having an internal surface area of at least 10 m²/g as calcium carbonate seed; and

(iv) up to 35% by weight of a fabric softening clay material;

where the weight ratio of crystal nucleus to clay material is less than 1.8:1.

The compositions of the invention necessarily contain at least one non-soap active detergent material, preferably in an amount of from 5 to 40% by weight. These materials are preferably selected from anionic and non-ionic non-soap active detergents and mixtures thereof.

Other active detergent materials, including soaps, may also be used, however this will normally be in admixture with anionic and/or non-ionic non-soap materials.

The non-soap (synthetic) anionic active detergent compound is usually the water-soluble alkali metal salt of an organic sulfate and sulfonate having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used in the sense of including the alkyl portion of higher alkyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulfates, particularly those obtained by sulfating higher (C8-C18) alcohols prepared, for example, from tallow or coconut oil, sodium and potassium alkyl (C9-C20) benzene sulfonates, particularly linear secondary sodium alkyl (C10-C15) benzene sulfonates; Sodium alkyl glyceryl ether sulfates, particularly those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulfates and sulfonates; sodium and potassium salts of sulfuric acid esters of higher (C8-C18) fatty alcohol alkylene oxide, particularly ethylene oxide, reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralized with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyltaurine; alkane monosulfonates such as those derived by reacting α-olefins (C8-C20) with sodium bisulfite and those derived from SO2-treated olefins. and Cl₂ and subsequent hydrolysis with a base to form a random sulfonate; and olefin sulfonates, which term is used to describe the material obtained by reacting olefins, particularly C₁₀-C₂₀ α-olefins, with SO₃ and subsequent neutralization and hydrolysis of the reaction product. The preferred anionic detergent compounds are sodium (C₁₁-C₁₅) alkylbenzenesulfonates and sodium (C₁₆-C₁₈) alkyl sulfates.

Suitable nonionic detergent compounds include, in particular, the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkylphenols with alkylene oxides, in particular ethylene oxide, either alone or with propylene oxide. Specific nonionic detergent compounds are alkyl (C6-C22) phenol ethylene oxide condensates, usually up to 25 EO, i.e. up to 25 units of ethylene oxide per molecule, the condensation products of aliphatic (C8-C18) primary or secondary linear or branched alcohols with ethylene oxide, usually up to 40 EO, and products prepared by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.

From an anti-hardening aspect, it has been found that if the active detergent system is a mixture of a soap and a non-soap anionic active detergent, and optionally with the further inclusion of a non-ionic active detergent material, there are particular advantages.

Particularly preferred active detergent systems contain from 2 to 17% non-soap anionically active detergent, up to 8% non-ionically active detergent, up to 8% soap and a non-ionic to soap ratio of from 3:1 to 1:3, more preferably from 2:1 to 1:2.

The term "soap" as used herein includes not only the usual alkali metal and alkaline earth metal salts of fatty acids, but also the organic salts which can be formed by complexing fatty acids with organic nitrogen-containing materials such as amines and derivatives thereof. Usually the soap contains salts of higher fatty acids containing from 8 to 24 carbon atoms, preferably from 10 to 20 carbon atoms in the molecule, or mixtures thereof.

Preferred examples of soaps include sodium stearate, sodium palmitate, sodium salts of tallow, coconut oil and palm oil fatty acids and complexes between stearic and/or palmitic fatty acid and/or tallow and/or coconut oil and/or palm oil fatty acids with water-soluble alkanolamines such as ethanolamine, di- or triethanolamine, and 2,2-dimethylethanolamine and N-containing ring compounds such as morpholine, 2'-pyrrolidone and their methyl derivatives.

Mixtures of soaps can also be used.

Particularly preferred are the sodium and potassium salts of the mixed fatty acids derived from coconut oil and tallow, i.e. sodium and potassium tallow and coconut soap.

An essential component of the composition is a water-soluble carbonate material as a builder. This is preferably sodium or potassium carbonate, or a mixture thereof.

Particular advantages have been found in connection with the present invention when the water-soluble carbonate material contains some bicarbonate salt. Accordingly, the carbonate salt may be completely neutralized, but preferably it is partially neutralized, for example a sesquicarbonate may be used as a partial replacement for the normal carbonate salt. A preferred carbonate to bicarbonate weight ratio is from 10:1 to 1:2, more preferably from 6:1 to 1:1. The amount of water-soluble carbonate material in the detergent composition may be varied widely, but the amount should be at least 5% by weight, such as from 10 to 40% by weight, preferably from 10 to 35% by weight. The amount of water-soluble carbonate material is determined on an anhydrous basis, although the salts may be hydrated either before or after they are incorporated into the detergent composition. It should be noted that it may also be desirable to limit the carbonate content to a lower level within the range mentioned so as to reduce the risk of internal damage following accidental ingestion, for example by children.

Subject to the maximum 40% limit of builder material in the compositions of the present invention, other builder materials may be present, although materials which act as seed poisons are best avoided. Examples of such other builder materials mentioned in the literature include fatty acids, selected water-soluble soaps, alkyl malonates, alkenyl or alkyl succinates, sodium fatty acid sulfonates, alkali metal orthophosphates, polyacetates, carboxylates, polycarboxylates, succinates and zeolites, or their amorphous equivalents.

The composition necessarily contains a water-insoluble particulate carbonate material. This material must be capable of acting as a crystal nucleus for the precipitate resulting from the reaction between the calcium hardness ions of the water and the water-soluble carbonate. Accordingly, this water-insoluble particulate material is a crystal nucleus for calcium carbonate, like calcium carbonate itself.

The water-insoluble particulate carbonate material must be finely divided with an internal surface area of at least 10 m²/g, and preferably at least 15 m²/g. The most preferred material has an internal surface area of 30 to 100 m²/g. Insoluble carbonate material with internal surface areas of over 100 m²/g can be used if such materials are economically available.

The internal surface area is measured by nitrogen absorption using the standard method of Brunauer, Emmet & Teller (BET method). A suitable apparatus for performing this method is a Carlo Erba Sorpty 1750 (registered trademark) instrument used according to the manufacturers instructions.

It is particularly preferred that the material with the high internal surface area be manufactured in the absence of poisons so that it retains its germicidal activity.

The insoluble carbonate material will usually have an average particle size of less than 10 µm as measured by sieve analysis, but may be granulated for ease of handling.

When the insoluble carbonate material is calcium carbonate, any crystalline form or mixture thereof may be employed, but calcite is preferred since aragonite and vaterite are less readily available commercially, and calcite is a little less soluble than aragonite or vaterite at most common washing temperatures. If any aragonite or vaterite is employed, it is usually in admixture with calcite. In the following general description, the term "calcite" is used to mean either calcite itself or any other suitable water-insoluble calcium carbonate seed material.

The selected level of calcite in the overall composition depends on the specific internal surface area as described above. The amount of calcite employed in the compositions should be in the range of 10% to 60%, more preferably 15% to 30%. A weight ratio of water-soluble carbonate material to calcite of less than about 4:1 is preferred.

Another essential component of the compositions of the present invention is a fabric softening clay material. This clay material should be a phyllosilicate clay with a 2:1 layered structure, with the non-silicate layer being either dioctahedral or trioctahedral coordinated and including the genus saponite, hectorite, montmorillonite or beidellite. Other 2:1 clay minerals such as talc, vermiculite, mica and chlorite have been found to be unsuitable for fabric softening because they are the unaltered minerals of the 1:1 layered clays of the kaolin group. Other aluminosilicate materials which do not have a layered structure, such as zeolites, are also unsuitable as fabric softening clay materials. Particularly suitable clay materials are the smectite clays described in detail in US Patent 3,959,155 (MONTGOMERY et al, assigned to THE PROCTER & GAMBLE COMPANY), particularly smectite clays as described in US Patent 3,936,537 (BASKERVILLE). Other disclosures of suitable clay materials for fabric softening purposes include European Patent Specification EP 26528-A (PROCTER & GAMBLE LIMITED).

The most preferred fabric softening clay materials include those of bentonitic origin, where bentonites are mainly montmorillonite-type clays together with various impurities, the content and nature of which depends on the source of the clay material.

The content of fabric softening clay material in the compositions of the invention should be sufficient to provide the fabrics with a softening benefit. A content of up to 35% by weight of the composition is suitable, preferably from 8% to 15%, these percentages being based on the content of the clay mineral as such. Levels of clay raw material higher than this level may be necessary if the raw material is from a particularly impure source.

The weight ratio of the seed crystal to the clay is less than 1.8 to 1. When a higher ratio, such as 3.0 to 1, is used, it has been found that the tissue softening benefit provided by the clay is insufficient.

The detergent composition may optionally contain any of the conventional ingredients in the amounts in which such ingredients are normally used in detergent compositions for washing fabrics.

One such optional ingredient is an alkali metal silicate, particularly sodium neutral, alkaline, meta- or ortho-silicate. A low level of silicate, for example 5 to 10% by weight, is usually beneficial in reducing corrosion of metal parts in fabric washing machines and can provide processing advantages. If higher levels of silicate up to a practical maximum of 30%, for example 10 to 20% by weight, are used, there can be a more noticeable improvement in detergency which can allow a reduction in the level of water soluble carbonate material. This effect appears to be particularly beneficial when the washing liquid is used in water with appreciable levels of magnesium hardness. The amount of silicate can also be used to some extent to control the equilibrium pH of the wash liquor, which is generally above 9, preferably 10 to 11 for an aqueous solution of the composition at the recommended concentration. Sodium silicate is usually added in concentrated aqueous solution, but the amounts are calculated on an anhydrous basis.

Examples of other optional ingredients include foam improvers such as alkanolamides, particularly the monoethanolamides derived from palm kernel oil fatty acids and coconut fatty acids, foam suppressors, oxygen-releasing bleaches such as sodium perborate and sodium percarbonate, peracid bleach precursors, chlorine-releasing bleaches such as trichloroisocyanuric acid, other fabric softening agents, inorganic salts such as sodium sulfate and, usually present in very small amounts, fluorescent agents, perfumes, enzymes such as proteases and amylases, germicides and dyes.

The detergent compositions may be prepared by any of the techniques conventionally used in the preparation of detergent compositions for washing fabrics, including slurry forming and spray drying processes.

Thus, the composition may contain spray dried beads containing at least some, such as all, of the active detergent system and the water soluble carbonate, whereas the calcite or other seed crystal is added as separate particles which may be pregranulated. The clay material may be included in the slurry for the spray dried beads or added separately to the composition either as a powder or as a pregranulated material. On the other hand, if the composition contains sodium silicate, it may be prepared by granulating a carbonate/silicate powder with the seed crystal material, ideally in the presence of a liquid binder such as sucrose solution, as described in more detail in South African Patent 87/8350 (UNILEVER PLC).

The invention will now be described in further detail in the following non-limiting examples.

In the examples, the following compositions were prepared by spray drying any ingredients to form a base powder and then adding other ingredients thereto. Composition: Spray dried ingredients Anionic active¹ Nonionic active² Soap³ Sodium carbonate Calcite⁴ Clay⁵ Sucrose Sodium sulfate Water and minor ingredients Other ingredients (added later) Sodium perborate⁴ Sodium silicate⁴ Antifoam granules Sodium bicarbonate Balance

Remarks:

1 - Dobane 112 (from Shell Chemicals) which is sulfonated to produce approximately a sodium benzene sulfonate in which the alkyl group contains from 10 to 15 carbon atoms.

2 - Dobanol 45-11 EO, which is approximately a C14/15 alcohol ethoxylated with 11 moles of ethylene oxide.

3 - Hardened tallow soap.

4 - Socal U3 (from Solvay) with a nominal internal surface area of 100 m²/g.

5 - RH412, a calcium bentonite from Morocco, from English China Clays.

6 - As the monohydrate.

7 - Has a Na₂O:SiO₂ ratio of 1:3.3.

8 - A grain containing a mixture of waxes, hydrocarbon oil and hydrophobized silica.

* - Composition A is listed for comparison purposes.

"Dobane", "Dobanol", "Socal" are registered trademarks.

EXAMPLE 1

Composition A was tested in the following manner. A 2.5 kg load of laundry containing a mixture of pre-washed and pre-hardened cotton plush controls was washed for 30 minutes at 40ºC or 95ºC in an automatic washing machine. The water hardness was 24ºFH and the product dosage was 140 g in 20 litres of washing liquid. A similar washing liquid was prepared containing the same amount of composition A together with 17 g of clay, therefore equivalent to a composition (B) containing about 12% clay. After each wash the controls were line dried and washed again. After 5 such washes the softness of the controls was determined by a panel of trained experts. The results are given as the number of merits - the higher the point value, the softer the cloth.

The results were: Temperature: Composition: Pre-washed controls Previously hardened controls

These results show that at both washing temperatures after 5 washes, product B, containing additionally added clay, is rated softer than the otherwise identical product without clay.

EXAMPLE 2

Compositions A and D were tested in the same manner as in Example 1, except that the laundry load contained naturally soiled articles, the washing temperature was 60ºC and for each wash 70 g of product was used for a prewash followed by 140 g of product as a main wash. The water hardness was 40ºFH and softness determinations were carried out after 2 and 6 washes.

The results were: Number of washes: Composition: Pre-washed controls Previously hardened controls

These results demonstrate the advantage of the invention when the clay is contained in the spray-dried base powder.

When composition D was modified by adding more clay and calcite and the modified composition was examined, it was found to be very similar to composition D in terms of softness behavior.

EXAMPLE 3

Compositions G to J were tested in the same manner as in Example 1, except that the washing temperature was 60ºC and the product dosage was 7.7 g/l. Instead of an automatic washing machine, a A laboratory scale apparatus fitted with a paddle stirrer was used, with the laundry load consisting of pre-washed cotton plush controls. Softness was determined after 1 wash. The initial pH of the wash liquid was measured in each case.

The results were: Composition: Total preference point value:

These results demonstrate the advantage of gradually replacing part of the carbonate salt by bicarbonate and the resulting decrease in the pH of the washing liquid.

When compositions G and J were tested in the same way, either at 40ºC or at 60ºC, and the laundry load contained two different standard cotton cleaning test cloths, the % detergency observed were as follows: Test cloth temperature

where Δ95 is the confidence limit for a significant difference at 95% probability. It can be seen that although composition J had the lower pH and was preferred in terms of softening, the observed wash performance results were not significantly different.

EXAMPLE 4

Compositions K to P were tested in the same manner as in Example 3 and the softness was determined after 1 wash.

The results were: Composition: Total preference point value:

These results demonstrate not only the benefit of the addition of bicarbonate to the compositions, but also that in the absence of bicarbonate there is an advantage for the inclusion of higher levels of soap and non-ionic actives.

Claims (6)

1. A detergent composition for washing and softening fabrics which is substantially free of phosphate builders and comprises: (i) 2 to 40% by weight of an active detergent system comprising at least one non-soap active detergent ingredient; (ii) 5 to 40% by weight of a builder comprising water-soluble carbonate in an amount of at least 5% by weight of the composition; and (iii) 10 to 60% by weight of a water-insoluble carbonate having a surface area of at least 10m²/g as calcium carbonate crystal nucleus; characterized in that the composition further comprises: (iv) up to 35% by weight of a fabric softening clay component; where the weight ratio of crystal nucleus to clay component is less than 1.8:1. 2. The composition of claim 1, wherein the water-soluble carbonate builder component comprises a mixture of an alkali metal carbonate salt and an alkali metal bicarbonate salt. 3. A composition according to claim 1 or 2, wherein the active detergent system comprises a non-soap, anionic, active detergent or a mixture of non-soap, anionic, active detergent with non-ionic active detergent, the amount of non-soap, anionic, active detergent being greater than the amount of any non-ionic, active detergent. 4. A composition according to any preceding claim, wherein the active detergent system comprises a mixture of soap and a non-soap, anionic, active detergent ingredient. 5. A composition according to claim 4, wherein the active detergent system also comprises a nonionic active detergent ingredient. 6. A composition according to any preceding claim, wherein at least a portion of the active detergent system and the water-soluble carbonate builder ingredient is present in the form of spray dried granules, the remaining ingredients, including at least a portion of the seed crystal, being present in the form of separate particles.