NO168488B - SOLUTION MIXING. - Google Patents

Abstract

Detergent composition with improved dispensability in automatic washing machines and based on a builder mixture of a water-soluble alkali metal carbonate, for example sodium carbonate, and a water-insoluble particulate carbonate seed crystal for calcium carbonate, for example calcite. The composition comprises a ternary active system containing 30-70% of anionically active material, for example an alkylbenzene sulfonate, 20-27 of a nonionic active material, for example ethoxylated alcohol, and at least 10% of soap. However, the soap must not exceed 10% of the mixture as a whole.

Description

The invention relates to detergent mixtures. These detergent mixtures are intended to be used for washing clothes in an automatic washing machine, and these mixtures contain little or no phosphorus-containing materials.

Detergent mixtures usually contain, in addition to a detergent active material, a detergency builder whose role, among other things, is to remove hardness ions from the washing bath which could otherwise reduce the effectiveness of the detergent active material. Water-soluble phosphate materials. have been in extensive use as washability builders. However, it has for a number of reasons, including eutrophication

which is alleged to be caused by phosphates, and also for reasons of price, there has been a desire to use instead alkali metal carbonates, especially sodium carbonate. However, alkali metal carbonate detergent builders suffer from a number of disadvantages. First, the reaction between the alkali metal carbonate and calcium ions present in hard water results in the formation of water-insoluble calcium carbonate which, depending on the conditions, may be in such a form that it is deposited on the washed laundry. Secondly, the reaction between the alkali metal carbonate and the calcium ions in the water is slow, especially at low temperatures, and is easily inhibited by materials that act as calcium carbonate build-up growth inhibitors, hereinafter referred to as poison. The result of this is that the concentration of calcium ions in the washing bath is not reduced as far or as quickly as desired, so that some free calcium ions are still available to reduce the effectiveness of the washing active material.

As a possible solution to this problem, it has been proposed

to include in the detergent mixture a water-insoluble material which would serve as a seed crystal for the calcium carbonate produced and would absorb the poison from the wash bath. Among other materials, finely divided calcite has been proposed as such a material, see British Patent 1,437,950.

The detergent active material can be selected from a number of classes of materials, but it is preferred to use a mixture of an anionic non-soap detergent, a non-ionic detergent and soap.

However, it has been found that detergent compositions containing such a ternary active system together with an alkali metal carbonate and calcite, in comparison with equivalent compositions containing phosphates as detergency builders, suffer from poor dispensability from automatic washing machines. In such machines, the user places an appropriate amount of washing powder in a dispenser where it is retained until the machine needs it. At an appropriate moment in the wash cycle, the water enters the dispenser and washes the powder into a feed pipe leading to the wash chamber of the machine. If the powder is not substantially washed out of the dispenser by this process, not only is it wasted, but after repeated use it will build up and eventually block the dispenser and/or feed tube. Alternatively, it makes it necessary for the user to clean the dispenser after each wash cycle.

The reason for the poor dispensability of the carbonate/calcite based powder in some machines is not fully understood, but we have surprisingly discovered that relatively good dispensability can be achieved with selected ternary active systems.

According to the invention, a detergent mixture is therefore provided which contains: (i) 5-25% by weight of a detergent-active system; as? comprises a mixture of (a) an anionic non-soap detergent active material; (b) a non-ionic detergent active material; and; (c) soap; (ii) 5-75% by weight of a water-soluble alkali metal carbonate.;, and; (iii) 5-60% by weight of a water insoluble; particle of carbonate material which is a seed crystal for calcium carbonate,

and the detergent mixture is characterized in that, based on the total weight of the components (a), (b;) and, fe) , the level of (a) is from 38 to 70%; the level of (b) is from 20 to 27%; and the level of (c) is from 10 to 35%, but not more than 8%, by weight of the entire mixture.

British patent document 2 104 912 describes in example 8 a calcite/carbonate-built mixture which has a ternary active system where the proportions of anionic, non-ionic agi soap within said system fall in the above specified ranges. However, the composition does not fall within the above definition as a whole because the soap content is stated to be 12%. Furthermore, the previously published British specification contains no teaching, exclusive or implicit, as to how to achieve improved dispensing properties with calcite/carbonate-based ternary systems.

It has been found particularly useful when the detergent composition contains: from 35 to 60% anionic active material;

from 21 to 26% nonionic active detergent; and from 15 to 35% soap.

The non-soap (synthetic) anionic detergent compound is usually the water-soluble alkali metal salt of an organic sulfate and sulfonate having alkyl radicals containing from 8 to 22 carbon atoms, the term alkyl being used to include the alkyl portion in higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphation of higher (Cg-C18) alcohols produced for example from tallow or coconut oil, sodium and potassium alkyl (Cg-C2Q) benzene sulphonates , especially sodium linear-secondary alk<y>1(C1Q-C15)-benzenesulfonates; sodium alkylglyceryl ether sulfates, especially such ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium and potassium salts of sulfuric acid esters of higher (Cg-C-^g)-f alcohol-alkylene oxide-, especially -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 methyl taurine; alkane monosulfates, such as those derived from the reaction of °C olefins (Cg-C2u-) with sodium bisulfide, and those derived from the reaction of paraffins with SC^ and Cl 2 and then hydrolysis with a base to produce randomized sulfonate ; and the olefin sulphonate, this term being used to describe the material which is made by reacting olefins, especially ci<g>~<C>20~ ^-olefins with SO^ and then neutralizing and hydrolysing the reaction product. The preferred anionic washing compounds are sodium (C16-C18) alkyl sulfates.

Suitable nonionic washing 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, especially ethylene oxide either alone or with propylene oxide. Specific non-ionic washing compounds are alkyl (C 8 -C 22 )-phenols-ethylene oxide condensates, generally 5-25 EO, i.e. 5-25 units of ethylene oxide per molecule, the condensation products of aliphatic (Cg-C18)-primary or -secondary linear or branched alcohols with ethylene oxide, generally 5-40 EO, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergents include long-chain tertiary amine oxides, long-chain tertiary phosphine oxides and dialkyl sulfoxides.

As used here, the term "soap" includes not only the usual alkali metal and alkaline earth metal salts of fatty acids, but also the organic salts that can be formed by complexing fatty acids with organic nitrogenous materials, for example amines and derivatives thereof. Generally, the soap comprises salts of higher fatty acids containing 8-24 carbon atoms, preferably 10-20 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 acids and/or tallow and/or coconut oil and/or palm oil fatty acids with water-soluble alkanolamines, for example ethanolamine, di- or tri-ethanolamine, N-methylethanolamine, N-ethylethanolamine, 2-methylethanolamine and 2,2-dimethylethanolamine

and N-containing ring compounds, for example 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 ingredient in the mix is a water-soluble carbonate material that builds. This is preferably sodium or potassium carbonate or a mixture thereof, for reasons related to price and efficiency. The carbonate salt is preferably fully neutralized, but it may be partially neutralized,

for example, a sesquicarbonate can be used as a partial replacement for the normal carbonate salt; the partial salts tend to be less alkaline and are therefore less effective.

The amount of water-soluble carbonate materials in the detergent mixture can be varied within wide limits, but the amount must

be at least 5% by weight, for example 10 - 40%, preferably 10 - 35% by weight, up to an amount of 75% by weight for special products. The amount of water-soluble carbonate

materials are determined on an anhydrous basis, although the salts may be hydrated either before or when they are incorporated into the detergent mixture. It should be noted that it may also be desirable to limit the carbonate content to a lower level within the aforementioned area, in order to reduce the risk of internal damage as a result of the product being incorrectly ingested, for example by children.

The mixture necessarily contains a water-insoluble particulate carbonate material. This material must have the ability to act as a seed crystal for the precipitation product resulting from the reaction between the calcium hardness ions in the water and the water-soluble carbonate. Thus, this water-insoluble particulate material is a seed crystal for calcium carbonate, for example calcium carbonate itself.

The water-insoluble particulate carbonate material should be finely divided and should have a surface area of at least 10 m 2 /g, preferably at least 15 m 2 /g. The particularly preferred material has a surface area of 30-100 m 2 /g. Insoluble carbonate material with surface areas in excess of 100 m 2 /g can be used, if such materials are economically available.

Surface area is measured by nitrogen absorption using the standard method of Bruayer, Emmet & Teller (BET). A suitable instrument for carrying out this method is a Carlo Erba Sorpty 1750 instrument which is operated according to the manufacturer's instructions.

It is most preferred that the material with a high surface area is produced in the absence of poison, so that it preserves its germinating

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 thereof may be used or a mixture thereof, but calcite is preferred, as aragonite and vaterite are less readily available commercially, and calcite is slightly less soluble than aragonite or vaterite at most common washing temperatures. When possibly aragonite or vaterite is used,

It is usually mixed with calcite. In the following general description, the term "calcite" is used in the sense of either calcite itself or any other suitable water-insoluble calcium carbonate seeding material.

The chosen level of calcite in the total mixture depends

of the specific surface area as described above. The amount of calcite used in the mixtures should be from 5 to 60%,

but preferably from 5 to 30%.

In addition to the water-insoluble carbonate material, the detergent-active material and the water-soluble carbonate material, it is possible to include small amounts of other washability builders, provided that the total amount of the washability builders does not exceed 85% by weight, so that there is room in the detergent mixture tlT.

other desirable ingredients.

Apart from the calcite, the detergent-active compounds and the washing ability builders, the detergent mixture may optionally contain any of the conventional ingredients in the quantities in which such ingredients are normally used in laundry detergent mixtures.

One such optional ingredient is an alkali metal silicate,

especially neutral sodium/alkaline, meta- or orthosilicate A low level of silicate, for example 5-10% by weight, is usually beneficial in terms of reducing the corrosion of metal parts in clothes washing machines, and it can give advantages in processing.

If higher levels of silicate are used up to a practical maximum of 30%, for example 10-20%, by weight, there may be a more noticeable improvement in detergency, which may allow some reduction in the content of water-soluble carbonate material. This effect appears to be particularly useful when the washing liquid is used in water with significant 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 in the range of 9-11, preferably 10-11, for an aqueous solution of the mixture at the recommended concentration. It should be noted that a higher pH value (i.e. above a pH of 10.5) tends to be more effective in detergency, but may be less desirable for home safety. Sodium silicate is usually available in concentrated aqueous solution, but the amounts are calculated on an anhydrous basis.

Examples of other optional ingredients include the suds enhancing agents, for example alkanolamides, especially the monoethanolamide derived from palm kernel fatty acids and coconut fatty acids, defoamers, oxygen releasing bleaches, for example sodium perborate and sodium percarbonate, peracid bleach precursors, chlorine releasing bleaches, for example trichloroisocyanuric acid , fabric softeners, inorganic salts such as sodium sulfate, and, usually present in very small amounts, fluorescent agents, perfumes, enzymes, for example proteases and amylases, germicides and dyes.

The detergent mixtures can be produced by any of the techniques that are commonly used in the production of laundry detergent mixtures, including in particular slurry and spray drying processes for the production of the washing powder.

The invention will now be illustrated by means of examples.

EXAMPLES 1 TO 7

Mixtures were prepared according to the following recipes. Each mixture was made into a powder form by spray drying the slurry of the indicated ingredients, with the exception of the sodium silicate, sodium perborate and TAED (when used), which were added separately to the spray dried base powder. The powders were atomized to a target moisture content of 3-4%.

Remarks

1 - Dobane 113, sodium salt of linear alkylbenzene sulphonate in which the alkyl group contains 10-15 carbon atoms. 2 - Synperonic A7, an alcohol with an alkyl chain length of 13-15 carbon atoms ethoxylated with an average of 7 ethylene oxide groups per molecule). 3 - hardened tallow sodium soap with the exception of examples 1 and 4, which used a 50:50 mixture of hardened tallow and hardened rapeseed sodium soap.

4 - measured as anhydrous.

5 - Socal U3 with a nominal surface area of

100 m<2>/g.

6 - in the form of the monohydrate.

In each example, 150g of powder was placed in a dispenser

in a HOOVER® automatic washing machine. Cold water was allowed to flow into the dispenser at a rate of 2 liters per minute for 2 minutes. The water had a hardness of 24°FH (i.e. a free calcium ion concentration of 24 x 10 -4 molar). The water pressure was 5 psi (0.35 kg/cm 2 ). After the water had been allowed to drain naturally from the dispenser, the weight of the powder residue in it was measured.

The results were as follows: A residual weight of less than 20 g in this test is considered acceptable. The following table also shows the percentage of anionic active, nonionic active and soap in each recipe.

These results show that the mixtures according to the invention (Examples 1 to 7) leave significantly less residue in the residue than the comparison mixtures A to D.

Claims (6)

1. Detergent mixture containing (i) 5-25% by weight of a detergent active system comprising a mixture of (a) an anionic non-soap detergent active material; (b) a nonionic detersive material; and (c) soap; (ii) 5-75% by weight of a water-soluble alkali metal carbonate; and (iii) 5-60% by weight of a water-insoluble particulate carbonate material which is a seed crystal for calcium carbonate; characterized in that, based on the total weight of components (a), (b) and (c), the level of (a) is from 38 to 70%; the level of (b) is from 20 to 27%; and the level of (c) is from 10 to 35%, but not more than 8%, by weight of the entire mixture. 2. Mixture as stated in claim 1, characterized in that the anionic non-soap-containing detergent active materials are a water-soluble alkali metal salt of an organic sulfate or sulfonate having an alkyl radical containing from 8 to 22 carbon atoms. 3. Mixture as set forth in any of the preceding claims, characterized in that the non-ionic detergent active material is selected from: (i) C6-C22~alkylphenol ethylene oxide condensates having 5-25 units of ethylene oxide per molecule, (ii) the condensation products of C8-C15 primary and secondary linear or branched alkylene alcohols having 5-40 units of ethylene oxide per molecule, and (iii) products made by condensation of ethylene oxide with the reaction products of ethylene oxide and ethylenediamine. 4. Mixture as set forth in any of the preceding claims, characterized in that the soap is a fatty acid salt with an alkali metal or alkaline earth metal. 5. Mixture as set forth in any one of the preceding claims, characterized in that the water-soluble particulate carbonate material is calcite. 6. Mixture as stated in any of the preceding claims, characterized in that it also contains 0-30% by weight of an alkali metal silicate.