NO163627B - LIQUID DETERGENTS. - Google Patents

Description

The invention relates to a floating cloth. detergent.

Liquid, non-aqueous full detergents for clothes are well known in the relevant art. For example, detergents of this type may comprise a liquid, non-ionic, surfactant in which particles of a builder are dispersed, e.g. a polyphosphate builder, as described for example in US patents 4,316,812, 3,630,929 and 4,264,466 and in British patents 1,205,711 and 1,270,040.

It is known that such suspensions can be stabilized against bottom precipitation by adding an inorganic, insoluble thickener or dispersant with a very large surface area, such as e.g. finely divided silicon dioxide with an extremely finely divided particle size (e.g. with a diameter of 5-100 Pm, as for example sold under the trademark Aerosil ) or the other very high volume inorganic carrier materials described in US patent 3,630,929, or by incorporating different clays, such as e.g. attapulgite, as described in US patent 4,264,466. Grinding down to very finely divided particle sizes also increases stability.

The present invention relates to liquid, non-aqueous full detergent for washing clothes and with a flow limit of 2-8 Pa, and the detergent is characterized by the fact that it comprises a suspension of an alkali metal polyphosphate building salt with a particle size of less than 10 µm in 30-70% by weight, based on the detergent, of a liquid, nonionic, surface-active agent prepared by condensing an alkoxylable organic hydrophobic compound with alkylene oxide, and 0.01-5% by weight of an organic phosphorus compound having an acidic -JPOH group and is a partial ester of phosphoric acid or phosphoric acid with a mono- or polyhydric alcohol.

According to the present invention, the stability of the suspension is increased by including in it an acidic, organic phosphorus compound with an acidic -POH group. This is a partial ester of phosphoric acid or phosphoric acid and a mono- or polyhydric alcohol, such as an alkanol, which is of a lipophilic nature, with e.g. over 5 carbon atoms, e.g. 8-20 carbon atoms. It has been found that as a result of the incorporation of rather small amounts of the acidic organic phosphorus compound, the suspension becomes significantly more stable against settling to the bottom on standing, but remains pourable. As described below, the incorporation of the acidic phosphorus compound thus increases the suspension's yield point, but it decreases its plastic viscosity.

It is believed that the use of the acidic phosphate bond can lead to the formation of a high-energy physical bond between the -POH part of the molecule and the surfaces of the inorganic polyphosphate builder, so that these surfaces acquire an organic character and become more compatible with the non- ionic surfactants.

The suspensions of the alkali metal polyphosphate builder, e.g. sodium tripolyphosphate (NTPF), in the nonionic surfactant has been shown to behave rheologically essentially in accordance with the Casson equation:

where i^ is the shear rate, tf is the shear force, <fQ is the yield stress (or yield strength), and *? oo is the infinite shear rate of plastic viscosity (which can be measured by determining the slope of a curve showing the square root of the shear force (as the ordinate) versus the square root of the shear rate). The yield point is the minimum shear force below which no yielding occurs (ie it corresponds to the intersection of the above curve with the ordinate at a shear rate of zero). It is therefore a criterion for stability. The plastic viscosity is a measure of flowability as soon as the flow limit has been overcome.

Yield strength (measured at 25°C)

must be at least 2 Pa and (for reasons of pourability and dispersibility) not more than 8 Pa, e.g. 3-7, and more preferably approx. 4 Pa.

To study this rheological behavior, a uniform, well-defined, shear rate viscometer (with coaxial cylinders or cone-plate geometry), such as a Rheometrics type rheometer is used.

The suspensions are preferably produced by grinding a mixture of non-ionic surfactant, particles of polyphosphate builder salt and the acidic, organic phosphorus compound in a mill which will grind the builder particles to a diameter below 10 Vm. The building salt will generally be added in the form of much larger particles with a diameter of over 40 ym, such as e.g. 100, 200 or 400 ym. If desired, the builder's salt can be mixed in advance with the acidic, organic phosphorus compound (e.g. by spraying the acidic compound dispersed or dissolved in water or in a volatile organic solvent, onto the builder's salt).

During painting, it is preferred that the amount of solid components is sufficiently high (e.g. at least 40%, such as approximately 50%) that the solid particles will come into contact with each other and not be shielded to a significant extent from each other by the non-ionic surface-active liquid. Mills in which downward grinding balls (ball mills) or similar mobile grinding elements are used have given good results. Thus, a laboratory attritor working in batches with steatite grinding balls can

with a diameter of 8 mm is used. To work on a larger scale, a continuously working mill with grinding balls with a diameter of 1 mm or 1.5 mm working in a very narrow gap between a stator and a rotor rotating at a relatively high speed (e.g. a CoBall mill), could be used. When such a mill is used, it is advantageous to pass the mixture of non-ionic surfactant and solids first through a mill which does not effect such fine grinding (eg a colloid mill), in order to reduce the particle size to below 100 ym ( eg about 40 ym) before the step where grinding to an average particle diameter below 10 ym takes place in the continuous ball mill.

The invention is described in more detail using the example below.

Example

A non-aqueous, built-up liquid full detergent is prepared by mixing non-ionic surfactant and sodium tripolyphosphate (NTPF) with other ingredients with and without an acidic organic phosphorus bond, as described below, and then grinding the mixture in an attritor ( to reduce the particle size of the suspended constituents to below 10 ym).The grinding conditions are identical in each case, i.e. grinding for 0.5 hour in an attritor containing steatite grinding balls with a diameter of 8 mm (Wieneroto W-1 .S attritor filled with 2.5 kg mixture).

The apparent viscosity at any shear rate can be calculated using the Casson equation and the relationship that the apparent viscosity is equal to shear force divided by the shear rate.

The acidic organic phosphorus compound of this example is a partial ester of phosphoric acid and a C-)g-Ci 8-alkanol ("Empiphos 5632"). It consists of approx. 35% monoester and 65% diester.

The detergent contains the following ingredients in the indicated amounts.

35% nonionic surfactant comprising a mixture of equal parts of (a) a relatively water soluble nonionic surfactant which forms a gel when mixed with water at 25°C, more specifically a C-] 3 -C15-alkanol which has been alkoxylated to introduce 10 ethylene oxide units and 5 propylene oxide units per alkanol moiety, and (b) a less water-soluble, nonionic surfactant, specifically a C-| 3-C1 5-alkanol which has been alkoxylated to introduce 4 ethylene oxide units and 7 propylene oxide units per alkanol unit.

12% of the reaction product prepared by mixing 100 g of succinic anhydride with 522 g of the nonionic surfactant known as "Dobanol 25-7". (the product of

ethoxylation of a C-] 2_c15-alkanol, the product having approx. 7 ethylene oxide units per molecule alkanol) and 0.1 g of pyridine (which here acts as an esterification catalyst), heating for 2 hours at 60°C, cooling and filtering to remove unreacted succinic acid material (an infrared analysis suggests that essentially all the free hydroxyl groups in the surfactant has been reacted to form an acidic half-ester in which the OH group of the non-ionic surfactant has been esterified with one carboxyl group from the succinic anhydride). 31.5% NTPF according to recipe A, 31.4% according to recipe B, 31.3% according to recipe C and 31.2% according to recipe D.

9% sodium perborate monohydrate, NaB03«H20.

4.5% tetraacetylethylenediamine. This is an activator for sodium perborate.

4% copolymer of approximately equal numbers of molecules of methacrylic acid and maleic anhydride, completely neutralized to form the sodium salt thereof ("Sokalan CP5"). This serves to inhibit crust formation (e.g. due to formation of dicalcium phosphate).

1% of the sodium salt of diethylenediaminepentamethylenephosphonic acid. This is a sequestering agent with a high stability constant for complex formation.

1% proteolytic enzyme slurry (in a nonionic surfactant) (Esperase ® ). 1% of a mixture of Na carboxymethylcellulose and hydroxymethylcellulose (an antigen precipitating agent) ("Relatin DM 4050").

0.5% perfume.

0.5% optical brightener (of the stilbene-4 type).

The NTPF used is preferably essentially an anhydrous material containing a small amount of NTPF hexahydrate (e.g. such an amount that the chemically bound water content is about 3%, which corresponds to about 1 molecule of H2O per .pentasodium tripolyphosphate molecule). Such an NTPF can be prepared by treating anhydrous NTPF with a limited amount of water. The presence of the hexahydrate slows down the rapid dissolution of NTPF in the wash bath and prevents it from caking. A suitable grade of NTPF is sold under the trade name "Thermphos NW", and the particle size of this NTPF in the form it is supplied is approx. 400 ym and its content of phase I approx. 60%.

The mixture can be easily dispensed with cold water in an automatic washing machine. Its specific weight is approx. 1.25, and it provides excellent washing when used in an amount of approx. 100 g per wash load (compared to 170 g per wash load for the usual powdered full detergents for clothes in standard European household washing machines (in which approx. 20 liters of water are used for the washing bath).

The delesters of phosphoric acid are known in the relevant art as foam suppressants and are mentioned for this purpose of use in US patent 4,264,466 (column 33, lines 34-45). The detergents according to this example are, however, of the low-foaming type when used for washing ordinary laundry in typical European, e.g. German washing machines with front loading. They produce little foam even in the absence of the delester of phosphoric acid and thus require no foam suppressant.

The acidic organic phosphorus compound may be selected from a number of different materials in addition to the partial esters of phosphoric acid and alkanols mentioned above. Thus, a partial ester of phosphoric acid or phosphoric acid with a mono- or polyhydric alcohol such as hexylene glycol, ethylene glycol, di- or triethylene glycol or higher polyethylene glycol, polypropylene glycol, glycerol, sorbitol, mono- or diglycerides of fatty acids, etc., can be used, in which one, two or more of the alcoholic OH groups in the molecule can be esterified with the phosphoric acid. The alcohol can be a non-ionic surfactant, such as e.g. an ethoxylated or ethoxylated-propoxylated higher alkanol, higher alkylphenol or higher alkyl amide. The carbon:phosphorus (C:P) atomic ratio in it

organic phosphorus compound is preferably at least 3:1, e.g. 5:1, 10:1, 20:1, 30:1 or 40:1. Among the suitable compounds are the surfactant phosphate esters described and summarized in Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd edition, Vol. 22 (1983) pp. 359-361.

The particular partial alkyl ester of phosphoric acid and the C15-C13 alkanol described in the above example is a solid material which generally swells but does not dissolve in the nonionic surfactant. It is supplied in the form of a powder. According to a preferred method used in this example, NTPF is added last (after the other solid ingredients have been added to the liquid mixture of nonionic surfactant and the reaction product of succinic anhydride and nonionic surfactant), and the powder of the phosphoric acid subalkyl ester is added just before NTPF. Acidic organic phosphorus compounds which are soluble in the non-ionic surfactant can also be used.

It is well known that the nonionic surfactants are characterized by the presence of an organic hydrophobic group and an organic hydrophilic group and that they are typically produced by condensation of an organic aliphatic or alkyl-aromatic hydrophobic compound with ethylene oxide (which is hydrophilic in nature). Practically any hydrophobic compound with a carboxy, hydroxy, amide or amino group with a free hydrogen atom attached to the nitrogen can be condensed with ethylene oxide or with polyethylene glycol which is the polyhydration product thereof, forming a nonionic surfactant . The length of the hydrophilic chain or polyoxyethylene chain can be easily adjusted to achieve the desired balance between the hydrophobic and hydrophilic groups. Typical suitable nonionic surfactants are those described in US Patents 4,316,812 and 3,630,929 as well as those described and summarized in the discussion of nonionic surfactants in the Kirk-Othmer "Encyclopedia of Chemical Technology ", 3rd edition, Vol. 22 (1983) pp. 360-379.

Non-ionic surfactants are often prone to forming gels with limited amounts of cold water. This can occasionally adversely affect a complete dispensing of the detergent from the usual dispensing devices found in standard automatic household washing machines used in Europe. In order to lower the gel formation temperature and thus facilitate an easier discharge, a carboxylic acid can be incorporated into the detergent as an antigelling agent. A preferred type of agent of this type is a compound with a carboxyl group attached to the residue of a nonionic surfactant, e.g. a half ester of succinic acid or of another dicarboxylic acid in which the OH group in the nonionic surfactant has been esterified with one carboxyl group from the acid. This material is preferably dissolved in the nonionic surfactant.

The polyphosphate builder salt is preferably an alkali metal (eg Na or K) tripolyphosphate, pyrophosphate (eg tetrasodium pyrophosphate) or hexamethaphosphate. It is preferred that these are mainly present in anhydrous form. Mixtures of two or more different polyphosphates can be used. The polyphosphate can also be used in a mixture with one or more other water-soluble surfactant builders.

Among the suitable builders are inorganic and organic builders' salts, such as e.g. the phosphates, carbonates, silicates, phosphonates, polyhydroxysulfonates or polycarboxylates, etc. Typical suitable builders are those described in US patents 4,316,812, 4,264,466 and 3,630,929.

As the detergents according to the invention, as indicated in the example, can be used in relatively small doses, it is desirable to supplement an eventual phosphate- or phosphate-forming builder (such as sodium tripolyphosphate) with an auxiliary builder, such as a polymeric carboxylic acid with a high ability to bind calcium, in a quantity of e.g. 1-10% of the detergent, in order to inhibit crust formation which would otherwise have occurred due to the formation of an insoluble calcium phosphate. Such auxiliary builders are well known in the relevant art.

The detergent preferably comprises a peroxygen bleach. This can be a peroxygen compound, e.g. an alkali metal perborate, percarbonate or perphosphate. Sodium perborate monohydrate is a particularly suitable material. The peroxygen compound is preferably used in mixture with an activator for this. Suitable activators are those described in US patent 4,264,466 or in column 1 of US patent 4,430,244. Polyacylated compounds are preferred activators, and among these, such compounds as tetraacetylethylenediamine (TAED) and glucose pentaacetate are particularly preferred.

The activator usually reacts with the peroxygen compound to form a peroxyacid bleach in the wash water. It is preferred to incorporate a sequestering agent with a high complex-forming ability to inhibit any unwanted reaction between such a peroxyacid and hydrogen peroxide in the washing solution in the presence of metal ions. Such a sequestering agent is an organic compound capable of forming a complex with Cu2 + ions, so that the stability constant (pK) of the formed complex is equal to or greater than 6, at 25°C, in water with an ionic strength of 0.1 mol/litre. pK is usually defined by the formula pK = -log K where K denotes the equilibrium constant. Thus, for example, the pK values for the formed complex of copper ions with NTA and EDTA under the stated conditions are respectively 12.7 and 18.8. Suitable sequestering agents include the sodium salts of nitrile triacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DETPA), diethylenetriaminepentamethylenephosphonic acid (DTPMP) and ethylenediaminetetramethylenephosphonic acid (EDITEMPA).

Other ingredients that may be present in the detergent are enzymes (e.g. proteases, amylases or lipases or mixtures thereof), optical whitening agents, antigen deposition agents or coloring agents (e.g. pigments or dyes) etc.

The detergent can also contain an inorganic, insoluble thickener or dispersant with a very high surface area, such as e.g. finely divided silica with an extremely finely divided particle size (eg, with a diameter of 5-100 nm, such as that sold under the trademark Aerosil® ) or the other large volume inorganic carrier materials described in US Patent 3,630,929, in amounts of 0.1-10%, e.g. 1-5%. In order to achieve the best results, however, it is preferred that detergents which form peroxyacids in the washing bath (e.g. detergents containing peroxygen compound and activator for this) are essentially free of such compounds and of other silicates. It has been shown, for example, that silicon dioxide and silicates promote the unwanted decomposition of the peroxyacid. Moreover, the use of these water-insoluble, inorganic materials can present other problems in the system. No high volume silicon dioxide or a clay of the chain structure type is required in the present detergents which are therefore preferably substantially free of such materials.

Although the average particle size of the solid materials in the preferred detergents has been reduced to less than 10 µm (e.g. typically only 5-10% of the content of the solid materials has a particle size above 10 µm), the present invention also applies to detergents that have not been ground as finely. It will be understood that a finer grinding increases the detergent's stability against sedimentation during standstill. According to Stokes' law, the smaller the particle size, the lower the sedimentation rate. If the yield point obtained is increased for a given grinding degree, the use of the acidic phosphorus compound can make it possible to increase the stability of detergents in which the average particle diameter is e.g. 15, 20 or 25 ym, e.g. by using increased amounts of the acidic phosphate compound to achieve the desired yield stress of at least 2 Pa.

In the detergents according to the invention, typical amounts of the components are as follows: Suspended surfactant builder, within the range 10-60, e.g. 20-50, e.g. 25-40, %.

Liquid phase comprising non-ionic, surface-active agent (and possibly dissolved carboxylic acid as a gel formation inhibitor) within the range 30-70, e.g. 40-60, %.

This phase may also include a diluent, such as glycol, e.g. polyethylene glycol (eg "PEG 400") or hexylene glycol.

Carboxylic acid as antifreeze in an amount sufficient to provide 0.5-10 parts (e.g. 1-6 parts, such as 2-5 parts) of -COOH (molecular weight 45) per 100 parts of the mixture of such a compound and the nonionic surfactant. The amount of this antifreeze is typically 0.01-1, e.g. 0.05-0.6, e.g. 0.2-0.5, part per part non-ionic surfactant.

Peroxygen f orb compound (e.g. sodium perborate monohydrate) in an amount of 2-15, e.g. 4-10, %.

11

Activator in an amount of 1-8, e.g. 3-6, %.

Sequestering agent with high complexing ability in an amount of 0.25-3, e.g. 0.5-2.%.

An acidic organic -POH compound in an amount of 0.01-5, e.g. 0.05-2, e.g. 0.1-1.%.

In the present description and in the patent claims, all stated parts are based on weight if nothing else is stated. In the examples, atmospheric pressure is used if nothing else is specified.

Claims (4)

<!>• Liquid, non-aqueous full detergent for washing clothes and with a flow limit of 2-8 Pa, characterized in that it comprises a suspension of an alkali metal polyphosphate building salt with a particle size of less than 10 µm in 30-70% by weight, based on the detergent, of a liquid, nonionic, surface-active agent prepared by condensing an alkoxylable organic hydrophobic compound with alkylene oxide, and 0.01-5% by weight of an organic phosphorus compound having an acidic POH group and being a partial ester of phosphoric acid or phosphoric acid with a mono- or polyhydric alcohol, 2. Full detergent according to claim 1, characterized in that the organic phosphorus compound is a partial ester of a higher alkanol and phosphoric acid. 3. Full detergent according to claim 1 or 2, characterized in that the atomic ratio of carbon: phosphorus in the phosphorus compound is at least 3:1. 4. Full detergent according to claims 1-3, characterized in that the non-ionic, surfactants are prepared by alkoxylation of a higher alkanol and contain ethylene oxide units and propylene oxide units.