NO840986L - Particulate, bleaching detergent - Google Patents

Description

The invention generally relates to bleaching detergents that contain a peroxygen compound as a bleaching agent together with an organic activator for this. The available detergents are particularly suitable for washing clothes. More specifically, the invention relates to granular, bleaching detergents which are capable of providing improved bleaching together with a significant improvement in the stability of the peroxy acid bleaching material in the washing solution.

Bleaching mixtures which emit active oxygen in the washing solution are extensively described in the relevant state of the art and are commonly used for washing clothes. Such bleaching mixtures generally contain peroxygen compounds, such as e.g. perborates, percarbonates or per-phosphates etc., which promote the bleaching activity by the formation of hydrogen peroxide in aqueous solutions. A significant disadvantage with which the use of such peroxygen compounds is fraught is that they do not seem optimally effective at the relatively low washing temperatures used in most household washing machines in the USA, i.e. temperatures in the range 26-55°C. For comparison, it can be mentioned that in Europe the washing temperatures are generally significantly higher and lie within a range of typically 32-94°C. Even in Europe and in such other countries which generally currently use washing temperatures close to the boiling temperature, there is, however, a tendency towards washing clothes at a lower temperature.

In an attempt to improve the bleaching activity of peroxygen bleaches, according to the state of the art, materials known as activators have been used together with the peroxygen compound. It is generally believed that the interaction between the peroxygen compound and the activator leads to the formation of a peroxyacid which is a more active bleaching material than hydrogen peroxide at low temperatures. A number of compounds have previously been proposed as activators for peroxygen bleaches, and of these can be mentioned carboxylic acid anhydrides, such as those described in US Patents 3298775, 3338839 and 3532634, carboxylic acid esters, such as those described in US Patent 2995905, N-acyl compounds , such as those described in US Patents 3,912,648 and 3,919,102, cyanoamines, such as those described in US Patent 4,199,466, and acyl sulfonamides, such as those described in US Patent 3,245,913.

The formation and stability of the peroxyacid bleaching materials in bleaching systems containing a peroxygen compound and an organic activator has been recognized in the art to present a problem. For example, US patent document 4255452 specifically concerns the problem of avoiding a reaction between peroxyacid and peroxygen compound. during the formation of what is described in the patent document as "useless products, i.e. the corresponding carboxylic acid, molecular oxygen and water". It is stated in the patent document that such a side reaction is "doubly harmful as peracid and percompound are destroyed simultaneously." The patent then describes certain polyphosphonic acid compounds as chelating agents which are claimed to inhibit the above-described peroxyacid-consuming side reaction and provide improved bleaching action. In contrast to the use of these chelating agents, it is stated in the patent document that other more commonly known chelating agents, such as ethylenediaminetetraacetic acid (EDTA) and nitrile triacetic acid (NTA), are essentially ineffective and do not improve the bleaching effect. It is therefore a disadvantage of the bleaching mixtures according to US patent 4 25545 2 that they necessarily exclude the use of common sequestering agents (salt separators), a number of which are less expensive and more easily available than the described polyphosphonic acid compounds.

The effect of silicates on the decomposition of peroxyacids in the washing and/or bleaching solution has so far been overlooked in the state of the art. In US patent documents 3860391 and 4292575 it is described that silicates are commonly used as additives to peroxide-containing bleaching solutions to stabilize the peroxide compounds therein. However, it is noted in these patent documents that the use of silicates in such bleaching solutions can lead to other problems during the bleaching operation, such as e.g. the formation of silicate precipitates which settle on the bleached product. The US patents therefore relate to methods for bleaching cellulose fibers with silicate-free bleaching solutions in which the peroxide stability is improved by means of compounds other than silicates.

In European published patent document 0028432 which was published on May 13, 1981, a granular laundry detergent is described which contains, among other things, a water-insoluble silicate and an organic activator compound for a peroxygen bleach. For such a laundry detergent, it is claimed that the pH values are of critical importance. It is specified more specifically that the pH in a 2% aqueous dispersion is 2-9, preferably 4-7. On page 7 of the patent, certain polyphosphonic acid compounds are described as strongly preferred components of the detergent, and it is stated in this connection that the polyphosphonates "have proven to be particularly effective in stabilizing organic peroxyacids against the generally harmful effects of water-insoluble silicates, especially such belonging to the zeolite and kaolin groups". The nature of such "harmful impact" is not specified. On page 38 of the patent, granular laundry detergents are described in examples VTII-X, and these do not contain sodium silicate. All such laundry detergents are stated to contain Deques 1® 2041 (ethylenediaminetetramethylenephosphonic acid). The laundry detergents according to the above examples also contain

a peroxygen compound activator incorporated into agglomerate particles consisting of the activator, a water-insoluble silicate compound and a nonionic surfactant.

Summary of the invention

The present invention relates to a particulate, bleaching detergent which is characterized by the fact that it comprises (a) a bleaching agent comprising a peroxygen compound in combination with an activator for this, and (b) at least one surface-

active agent consisting of anionic, cationic, non-

ionic, ampholytic éiler' zwitterionic surfactants, the bleaching detergent being essentially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise the activator, a water-insoluble silicate compound and a non-ionic surfactant.

The present bleaching detergent is used for washing stained and/or soiled materials by bringing such materials into contact with an aqueous solution of the present bleaching detergent.

The present invention is based on the recognition of the unwanted loss of peroxyacid in the aqueous washing solution due to reaction between peroxyacid and a peroxygen compound (or more precisely hydrogen per-

oxide formed from a similar peroxygen compound) during the formation of molecular oxygen is markedly reduced in bleaching systems which are essentially free of water-soluble silicate compounds. Although it is not desired here to be bound by any particular theory regarding the occurring reaction mechanism, it is assumed that the presence of water-soluble silicates in bleaching systems containing a peroxygen compound/activator catalyzes the above-mentioned reaction between peroxyacid and hydrogen peroxide which leads to active oxygen is lost from the washing solution, which would otherwise have been available for bleaching. It has been recognized within the state of the art that metal ions, such as e.g. ions of iron or copper, catalyze the splitting of hydrogen peroxide and also the reaction between peroxyacid and hydrogen peroxide.

As far as such metal ion catalysis is concerned, however, it is

according to the invention has surprisingly been discovered by common sequestering agents, such as EDTA or NTA, which according to the state of the art have been considered to be ineffective in terms of inhibiting the above-mentioned peroxyacid-consuming reaction (see e.g. the statement in US patent document 4225452, column 4), can be incorporated in the detergents according to the invention to stabilize the peroxyacid in the solution.

The term "water-soluble silicate compounds" refers to compounds, such as sodium silicate, which are essentially soluble in aqueous laundry solutions and usually present in ordinary bleaching detergents, but which are essentially completely dissolved in the detergents according to the invention. According to the present invention, however, the aim is to incorporate essentially water-insoluble silicates, primarily aluminum silicate materials, such as clays or zeolites, into the present bleaching detergents, since water-soluble silicate compounds are considered to be far more harmful to peroxyacid stability than water-insoluble ones materials, such as aluminosilicates.

According to a preferred embodiment of the invention, the present bleaching detergents also contain a sequestering agent to improve the stability of the peroxy acid bleach compound in the solution by inhibiting its reaction with hydrogen peroxide in the presence of metal ions. The term "sequestering agent" as used here applies to organic compounds that are capable of • forming a complex with Cu<2+> ions, so that the complex's stability constant (pK) is equal to or greater than 6 in water at 25°C and an ionic strength of 0.1 mol/litre. pK is usually defined using the formula: pK - - log K, where K denotes the equilibrium constant. Thus, e.g. The pK values for complexes of copper ions with NTA and EDTA under the indicated conditions or 12.7 and 18.8. The term "sequestering agent" is therefore used here in

a sufficiently limited sense that inorganic compounds commonly used in detergent recipes,

such as building salts, are excluded. Particularly suitable sequestrants include EDTA, diethylenetriamin-pentaacetic acid (DEPTA) or the various phosphonate sequestrants sold under the trademark Dequest<®>, e.g. with the quality labels 2000, 2006, 2041, 2051 or 2060.

According to another embodiment of the invention is

the present bleaching systems are further limited to certain water-soluble, silicate-free systems that are described in the prior art, in that the use of sequestering agents in the present bleaching systems is limited to those that have a stability constant of not more than 20 for Cu 2 4* complex formation in water at 25 C and an ionic strength of

0.1 mol/litre. This limitation necessarily excludes the presence of polyphosphonic acid compounds, such as Dequesl<®>2041 (ethylenediaminetetramethylenephosphonic acid) and Dequest® 2060 (diethylenetriaminepentamethylphosphonic acid) in the bleaching system according to the invention as the above-mentioned sequestering agents have stability constants above 20. Suitable sequestering agents for this embodiment of the invention therefore include the sodium salts of nitrile triacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), ethylenediamine, tetramine, i.e. N-(CH2~CH2-NH2)3, bis(aminoethyl)-glycolether-NNN'N'-tetraacetic acid (EGTA), and N(CH2- P03H2)3 which is sold under the trademark Dequest<®>2000. EDTA and the above-mentioned Dequest® 2000

are particularly preferred for use according to this embodiment of the invention.

Detailed description of the invention

The bleaching detergents according to the invention comprise two essential components, i.e. (a) a bleaching agent and (b) a detergent-active surfactant.

The bleach that can be used in such detergents comprises a peroxygen compound in combination with an organic activator for this.

The peroxygen compounds which can be used in the present detergents include compounds which release hydrogen peroxide in aqueous media, such as e.g. alkali metal perborates, e.g. sodium perborate or potassium perborate, alkali metal perphosphates or alkali metal percarbonates. The alkali metal perborates are generally preferred because they are readily available commercially and relatively inexpensive.

Common activators, such as those described e.g. in column 4 of US patent 4259200, are suitable for use together with the above-mentioned peroxygen compounds. The poly-acylated amines are generally of particular interest, and tetraacetylethylenediamine (TAED) in particular is a highly preferred activator. TAED is preferably present in the detergent according to the invention in the form of "coated" granules containing TAED and a suitable carrier material, e.g. a mixture of sodium and potassium triphosphate. Such coated TAED granules are usually prepared by mixing finely divided particles of sodium triphosphate and TAED with each other, after which an aqueous solution of potassium triphosphate is sprayed onto such a mixture using conventional granulating equipment, such as a rotary disc granulator. A typical production method for this type of coated TAED is described in US patent 4 283302. The granules of TAED have a preferred particle size distribution as follows: 0-20%

greater than 150 µm, 10-100% greater than 100 µm but less than 150 µm, 0-50% less than 75 µm and 0-20% t-) less than 50 µm. Another particularly preferred particle size distribution is such that the median particle size for TAED is 160 µm, i.e. that 50% of the particles have a size above 160 µm. The above-mentioned size distributions refer to the TAED present in the coated granules and not to the coated granules as such. The molar ratio between peroxygen compound and activator can vary greatly depending on the particular choice of peroxygen compound and activator. However, molar ratios of 0.5:1-25:1 are generally suitable to achieve a satisfactory bleaching result.

The bleach may optionally also contain a peroxy acid compound together with the peroxygen compound and the activator. Useful peroxyacid compounds include water-soluble peroxyacids and water-soluble salts thereof. The peroxyacids can be represented by the following general formula:

wherein R denotes an alkylene group with 1-20 carbon atoms or a phenylene group, and Z denotes one or more groups consisting of hydrogen, halogen, alkyl, aryl or anion-active groups.

The organic peroxyacids and their salts may contain 1-4, preferably 1 or 2, peroxy groups and may be aliphatic or aromatic. The preferred aliphatic peroxy acids include diperoxyazelaic acid, diperoxydodecanedioic acid and monoperoxysuccinic acid. Among the aromatic peroxy acid compounds useful for the present detergents, monoperoxyphthalic acid (MPPA), especially the magnesium salt thereof, or diperoxyterephthalic acid are particularly preferred. A detailed description of the preparation of MPPA and its magnesium salt is set forth on pages 7-10 of European Published Patent 0027693 which was published on April 29, 1981.

The bleaching detergents according to the invention are distinctive in that they are essentially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which are essentially made of a mixture of three components, i.e. the organic activator for the peroxygen compound, a water Soluble silicate compound, such as clay or zeolite, and a non-ionic surfactant, such a mixture constituting at least 80% by weight of the agglomerate particles. The agglomerate particles which are excluded for use in the present bleaching detergents are of the type formed in such equipment as a plate granulator, and serve to incorporate the bleach activator into a base mass of materials, as described in published European patent 0028432. According to a particular embodiment of the invention, the bleaching tanks are further characterized by the fact that they are essentially free of sequestering agents with a stability constant for Cu2 + complex formation above approx. 20 in water at 25°C and an ionic strength of 0.1 mol/litre.

The water-insoluble silicate materials which can be advantageously used in the present bleaching detergents are preferably aluminum silicates, such as zeolites or clays of the smectite type. The crystalline types of zeolite that can be used include those described in the "Zeolite Molecular Series" by Donald W. Breck, published in 1974 by John Wiley&Sons, typical commercially available zeolites being listed in Table 9.6 on pages 747-749 of the textbook . Zeolite structures of type A are particularly desirable and are extensively described in the relevant state of the art, see e.g. page 133 of the above book by Breck and also US patent 2882243." Zeolites particularly useful as builder's salts in coarse or full detergents.

The above-mentioned clays of the smectite type are three-layered clays which are characterized by the fact that the layer structure is able to increase its volume several times by swelling or expanding when in the presence of water, forming a thixotropic, gelatinous material. There are two groups of clays of the smectite type. Within the first group, aluminum oxide is present in the silicate crystal lattice, and within the second group, magnesium oxide is present in the silicate crystal lattice. Atomic substitution with iron, magnesium, sodium, potassium or calcium etc. can take place in the crystal lattice of smectite clays. It is common to distinguish between clays on the basis of their dominant cation. For example, a sodium clay is a clay in which the cation is mainly sodium. What concerns the available bleaching detergents, is. aluminum silicates in which sodium is the dominant cation preferred, such as e.g. bentonite clays. Among the bentonite clays, those from Wyoming (commonly referred to as "western" or Wyoming bentonite) are particularly preferred. Calcium and magnesium clays are also usable although they are less preferred for the detergents according to the invention.

Preferred swelling bentonites are sold under the trade name "Mineral Colloid" as industrial bentonites. These materials, which are the same as those previously sold under the trade name "Thixo-Jel", are selectively pit-mined and are enriched bentonites, and those considered the most useful are sold under the trade name "Mineral Colloid" from No. 101 and further, corresponding to "Thixo-Jel" No. 1, 2, 3 and 4. Such materials have a pH (6% concentration in water) within the range 8-9.4, a maximum content of free moisture of approx. . 8% and specific weights of approx. 2.6, and for the powdered grade at least 85% (preferably 100%) passes through a 200 mesh sieve (U.S. sieve standard). The bentonite is more preferred than bentonite in which substantially all particles (ie at least 90% of these, preferably over 95%) pass through a No. 325 sieve, and it is most preferred that all particles pass through such a sieve. The swelling ability of the bentonites in water is usually in the range 3-15 ml/g, and their viscosity measured at a 6% concentration in water is usually 8-30 centipoise.

According to a particularly preferred embodiment of the invention, the carrier particles comprise agglomerates of finely divided bentonite with a particle size smaller than corresponding to the mesh openings in a sieve no. 200 and agglomerated into particles with a size that is essentially within the range from sieve no. 10 to sieve no. 100, with a bulk density of 0.7-0.9 g/ml and a moisture content of 8-13%. Such agglomerates include 1-5% of a binder or agglomerating agent to facilitate the maintenance of the structural integrity of the agglomerates until they are added to water in which they are intended to be broken down and dispersed. A detailed description of the production method for such agglomerates is given in US patent application 366587 filed on April 8, 1982.

Instead of using the bentonites of the "Thixo-Jel" or "Mineral Colloid" type, similarly competitive products can also be used, such as the product sold under the trade name "General Purpose Bentonite Powder, 325 mesh"

having particles of which at least 95% are finer than a diameter of 44 µm (wet particle size) and at least 96% are finer than a diameter of 74 µm (dry particle size).

Such a hydrated aluminum silicate consists mainly of montmorillonite (at least 90%) together with smaller amounts of feldspar, biotite and selenite. A typical analysis on an "anhydrous" basis is 63.0% silicon dioxide, 21.5% aluminum oxide, 3.3% trivalent iron (as Fe-^O.^ 0.4% divalent iron.

(as FeO), 2.7% magnesium (as MgO), 2.6% sodium and potassium (as Na2O), 0.7% calcium (as CaO), 5.6% water of crystal (as H2O) and 0.7 % trace elements. Although the "western" bentonites are preferred, it is also possible to use synthetic bentonites, such as those which can be prepared by treating Italian or similar bentonites containing relatively small proportions of exchangeable monovalent metals (sodium and potassium) with alkaline materials, such as sodium

carbonate, to increase the cation exchange capacity of such products.

It is believed that the Na20 content in the bentonite should be at least 0.5%, preferably at least 1%, and more preferably at least 2%, so that the clay will be satisfactorily swelling with good softening and dispersing properties in aqueous suspension. Preferred swelling bentonites of the synthetic types described are sold under the trade names "Laviosa" and "Winkelmann", e.g. "Laviosa AGB" and "Winkelmann G-13".

The detergents according to the invention contain one or more surfactants consisting of anionic, non-ionic, cationic, ampholytic or zwitterionic surfactants or cleaning agents. Among the anionic surfactants that can be used in the detergents according to the invention, are the surfactant compounds that contain an organic hydrophobic group with 8-26 carbon atoms • preferably 10-18 carbon atoms, in their molecular structure and at least one water-solubilizing group consisting of sulfonate, sulfate , carboxylate, phosphonate or phosphate so that a water-soluble surfactant or cleaning agent is obtained.

Examples of suitable anionic cleaning agents include soaps, such as the water-soluble salts (eg sodium, potassium, ammonium or alkanolammonium salts) of higher fatty acids or resin salts containing 8-20 carbon atoms, preferably 10-18 carbon atoms. Suitable fatty acids can be obtained from oils and waxes of animal or vegetable origin, e.g. tallow, shortening, coconut oil or mixtures thereof. The sodium and potassium salts of the fatty acid mixtures that form from coconut oil and tallow, e.g. sodium coconut soap or potassium tallow soap, are particularly useful.

The anionic group of cleaning agents or surfactants also includes the water-soluble, sulfated and sulfonated surfactants with an alkyl radical of 8-26, preferably 12-22, carbon atoms (the term "alkyl"4 includes the alkyl part of the higher acyl radicals). Examples of the sulfonated, anionic surfactants are the higher alkyl mononuclear aromatic sulfonates, such as the higher alkylbenzene sulfonates containing 10-16 carbon atoms in the higher alkyl group in a straight or branched chain, such as e.g. the sodium, potassium or ammonium salts of higher alkylbenzenesulfonates, higher alkyltoluenesulfonates or higher alkylphenolsulfonates.

Other suitable anionic surfactants are the olefin sulfonates, including long-chain alkenesulfonates, long-chain hydroxyalkanesulfonates or mixtures of alkenesulfonates and hydroxyalkanesulfonates. The olefin sulfonate surfactants can be prepared in the usual way by reacting SO^ with long-chain olefins of 8-25/preferably 12-21, carbon atoms, such olefins having the formula RCH=CHR^ in which R is a higher alkyl group of 6-2 3 carbon atoms and R^en alkyl group of 1-17 carbon atoms or hydrogen, forming a mixture of sultones and alkenesulfonic acids which are then treated to convert the sultones to sulphonates. Other examples of sulfate or sulfonate surfactants are paraffin sulfonates with 10-20, preferably 15-20, carbon atoms. The primary paraffin sulfonates are prepared by reacting long-chain α-olefins with bisulfites. Paraffin sulfonates with the sulfonate groups distributed along the paraffin chain are described in US patent documents 2503280, 2507088, 3260741 and 3372188 and in West German patent document 735096.

Other suitable anionic surfactants are sulfated,

ethoxylated higher fatty alcohols of the formula RO(C~H.O)SO-.M,

2 4 m 3 wherein R is a fatty alkyl group with 10-18 carbon atoms, m is 2-6 (preferably with a value from 1/5 to 1/2 the number of carbon atoms in R), and M is a solubilizing salt-forming cation, which an alkali metal, ammonium, lower alkylamine or lower alkanolamine cation, or a higher alkylbenzene sulfonate in which the higher alkyl group has 10-15 carbon atoms. The proportion of ethylene oxide in the polyethoxylated higher alkane sulphate is preferably 2-5 mol ethylene oxide groups per mol of anionic surfactant, with 3 mol being most preferred, especially if the higher alkanol has 11-15 carbon atoms. In order to maintain the desired hydrophilic-lipophilic balance when the number of carbon atoms in the alkyl chain is in the lower part of the range 10-18 carbon atoms, the surfactant's ethylene oxide content can be reduced to approx. 2 molecules per molecule, but when the higher alkanol has 16-18 carbon atoms within the upper part of this range, the number of ethylene oxide groups can be increased to 4 or 5 and in some cases to as many as 8 or 9. Similarly, the salt-forming cation can be changed for to achieve the best resolution. It can be made of any solubilizing metal or radical, but it will most often be made of an alkali metal, e.g. sodium, or of ammonium. If lower alkylamine or alkanolamine groups are used, the alkyl groups and alkanols will usually contain 1-4 carbon atoms,

and the amines and alkanolamines may be mono-, di- or tri-substituted, as e.g. in monoethanolamine, diisopropanolamine or trimethylamine. A preferred polyethoxylated alcohol sulfate surfactant is sold under the trade name "Neodol 25-3S".

The most preferred water-soluble anionic surfactant compounds are the ammonium and the substituted ammonium (such as mono-, di-, or triethanolamine), alkali metal (such as sodium or potassium), or alkaline earth metal (such as calcium or magnesium) salts of the higher alkylbenzene sulfonates , olefin sulfonates or higher alkyl sulfates. Among the above-mentioned anionic compounds, the most preferred are the sodium linear alkyl benzene sulfonates (LABS), especially those in which the alkyl group is a straight-chain alkyl radical of 12 or 13 carbon atoms.

The non-ionic, synthetic, organic surfactants are characterized by the presence of an organic hydrophobic group and an organic hydrophilic group and are typically produced by condensation of an organic aliphatic or alkylaromatic hydrophobic compound with ethylene oxide (of a hydrophilic nature). Practically any hydrophobic compound with

a carboxyl, hydroxyl, amide or amino group with a free hydrogen atom attached to the nitrogen atom can be condensed with ethylene oxide or with polyethylene glycol which is the polyhydrated product of ethylene oxide, forming a non-ionic 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.

The nonionic surfactant used is preferably a poly-lower alkoxylated higher alkanol in which the alkanol has 10-18 carbon atoms and the number of lower alkylene oxide molecules (with 2 or 3 carbon atoms) is 3-12. Among such materials, it is preferred to use those in which the higher alkanol is a higher fatty alcohol with 11-15 carbon atoms and which contains 5-9 lower alkoxy groups per molecule. The lower alkoxy group is preferably an epoxy group, but in some cases this can advantageously be mixed with a propoxy group, the latter, if present, usually making up a minor (less than 50%) component. Examples of such compounds are compounds in which the alkanol has 12-15 carbon atoms and with approx. 7 ethylene oxide groups present per molecule, e.g. "Neodol 25-7" and "Neodol 23-6.5". The former is a condensation product of a mixture of higher fatty alcohols which on average have 12-15 carbon atoms, with approx. 7 molecules of ethylene oxide,

and the latter is a corresponding mixture in which the carbon atom content in the higher fatty alcohol is 12-13 and the number of ethylene oxide groups per molecular average is approx.

6.5. The higher alcohols are primary alkanols. Other examples of such surfactants include Tergitol 15-S-7

and Tergitol 15 S-9 which are both linear, secondary alcohol ethoxylates. The former is a mixed ethoxylation product of a linear, secondary alkanol having 11-15 carbon atoms, with 7 molecules of ethylene oxide, and the latter is a similar product, but with 9 molecules of reacted ethylene oxide.

Also the nonionic surfactants with higher molecular weight,

like for example. "Neodol 45-11", which are similar ethylene oxide condensation products of higher fatty alcohols, the higher fatty alcohol having 14-15 carbon atoms and the number of ethylene oxide groups per molecule is approx. 11, can be used in the present detergents.

Zwitterionic surfactants, such as the betaines or sulfo-betaines of the following formula, are also useful:

in which R is an alkyl group with 8-18 carbon atoms, R 2 and R-.

are both an alkyl or hydroxyalkyl group containing 1-4 carbon atoms, R 1 is an alkylene or hydroxyalkylene group containing 1-4 carbon atoms, and X is C or S:O. The alkyl group may contain one or more intermediate bonds, such as amide, ether or polyether bonds, or non-functional substituents, such as hydroxyl or halogen,

which does not significantly affect the group's hydrophobic nature. When X is C, the surfactant is called a betaine, and when X is S:0, the surfactant is called a sulfobetaine or sultain.

Cationic surfactants can also be used. These include surface-active, detergent-active compounds that contain an organic hydrophobic group that forms part of a cation when the compound is dissolved in water, and an anion-active group. Typical cationic surfactants are amine or quaternary ammonium compounds.

Examples of suitable synthetic cationic surfactants include normal primary amines of the formula RNH2, wherein R is an alkyl group of 12-15 carbon atoms, diamines of the formula RNHC^H^NH-j, wherein R is an alkyl group of 12-22 carbon atoms, such as N -2-aminoethylstearylamine or N-2-aminoethylmyristylamine, amide-linked amines, such as those having the formula R1CONHC2H4NH2, in which is an alkyl group of 8-20 carbon atoms, such as N-2-aminoethylstearylamide or N-aminoethyl1-myristylamide, quaternary ammonium compounds in which typically one of the groups attached to the nitrogen atom is an alkyl group with 8-22 carbon atoms and where three of the groups attached to the nitrogen atom are alkyl groups with 1-3 carbon atoms, including alkyl groups with inert substituents, such as phenyl groups, and where an anion, such as halogen, acetate or metho-sulphate etc., are present. The alkyl group can contain intermediate bonds, such as amide bonds, which do not significantly affect the group's hydrophobic nature, e.g. stearyl amide propyl quaternary ammonium chloride. Typical quaternary ammonium surfactants are ethyldimethylstearylammonium chloride, benzyldimethylstearylammonium chloride, trimethylstearylammonium chloride, trimethylcetylammonium bromide, dimethylethyllaurylammonium chloride, dimethylpropylmyristylammonium chloride or the corresponding methosulphates or acetates.

Ampholytic surfactants are also suitable for the detergents according to the invention. Ampholytic surfactants are well known in the art, and a number of useful surfactants within this group are described by Schwartz, Perry and Berch in the above-mentioned "Surface Active Agents and Detergents." Examples of suitable amphoteric surfactants include alkyl-3-iminodipropionates, RN(C2H4COOM)2, alkyl-Ø-aminopropionates, RN(H)C^H^COOM, and long-chain imidazole derivatives of the general formula:

wherein R of each of the above formulas is an acyclic hydrophobic group of 8-18 carbon atoms and M a cation to neutralize the charge of the anion. Particularly useful amphoteric surfactants include the disodium salt of undecylcycloimidiniumethoxyethionic acid-2-ethionic acid, dodecyl-3-alanine and the inner salt of 2-trimethylaminolauric acid.

The bleaching detergents according to the invention optionally contain a detergent builder of the type that is commonly used in detergent recipes. Useful builders include any of the usual inorganic, water-soluble builder salts, such as water-soluble salts of phosphates, pyrophosphates, orthophosphates, polyphosphates.. or carbonates etc. Organic builders include water-soluble phosphonates, polyphosphonates, polyhydroxysulfonates, polyacetates, carboxylates, polycarboxylates or succinates etc.

Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, pyrophosphates or hexametaphosphates. The organic polyphosphonates include in particular e.g. the sodium or potassium salts of ethane-1-hydroxy-1,1-diphosphonic acid or the sodium or potassium salts of ethane-1/1,2-triphosphonic acid. Examples of these and other phosphorus-containing building compounds are described in US patents 3213030, 3422021, 3422137 and 3400176. Pentasodium tripolyphosphate and tetrasodium pyrophosphate are

especially preferred water-soluble organic builders.

Specific examples of non-phosphorous inorganic builders include water-soluble inorganic carbonate

or bicarbonate salts. Alkali metal, e.g. sodium or potassium, the -carbonates or -bicarbonates are particularly useful in the present detergents.

Water-soluble, organic builders can also be used.

For example, alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates or polyhydroxysulfonates are useful builders for the detergents according to the invention. Specific examples of polyacetate and polycarboxylate builders include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrile triacetic acid, benzene polycarboxylic (ie, penta- or tetra-) acids, carboxymethoxysuccinic acid or citric acid.

Water-soluble builders can also be used, and especially

the complex silicates, and more particularly the complex sodium-aluminium silicates, such as zeolites, e.g. zeolite 4A with a zeolite molecular type in which the monovalent cation is sodium and the pore size is approx. 4 Å. The production of such a zeolite type is described in US patent 3114603. The zeolites can be amorphous or crystalline and have water of hydration, as is well known in the relevant art.

An inert, water-soluble filler salt can optionally be included in the laundry detergents according to the invention. A preferred filler salt is an alkali metal sulfate, such as potassium or sodium sulfate, the latter being particularly preferred.

Various auxiliary additives can be incorporated

in the laundry detergents according to the invention. These include

generally perfumes, coloring materials, e.g. pigments or organic dyes, bleaching agents such as sodium perborate, antigen deposition agents such as alkali metal salts of carboxymethylcellulose, optical brighteners such as anion-active, cation-active or non-ionic brighteners, or foam stabilizers such as alkanolamides, etc. All of these are well known in laundry technology for use in detergents. Fluidity-promoting agents, which are designated as flow aids, can also be used so that the particulate detergents are maintained as free-flowing beads or powder. Starch derivatives and special clays are commercially available as additives that improve the flowability of otherwise sticky or paste-like particulate detergents, among others two such clay additives are sold

(6)

under the trade marks Satintone^ and "Microsil".

A preferred bleaching detergent according to the invention typically comprises (a) 2-50% by weight of a bleaching agent comprising a peroxygen compound together with an activator for this, (b) 5-50% by weight of a surface-active cleaning agent, (c) 1-60% by weight % of a detergent builder salt and (d) 0.1-10% by weight of a sequestering agent. Such a bleaching detergent is characterized by being essentially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise the activator, a water-insoluble silicate compound and a non-ionic surfactant. The rest of the mixture will mainly comprise water, filler salts, such as e.g. sodium sulfate, and minor additives selected from the many different auxiliary additives described above.

The particulate, bleaching detergents according to the invention are produced by mixing the bleaching agent and the possible sequestering agent with the spray-dried detergent which has such a recipe that the use of water-soluble silicate compounds, most often sodium silicate, is avoided. The presence of very small amounts of water-soluble silicate compounds in the final detergents, i.e. below 0.5%, preferably below 0.2%, and preferably not above 0.1%, which may occur when using silicate-containing pigments or dyes or by contact between the aqueous kneader slurry and residual amounts of sodium silicate in the spray tower, it is however aimed at may be present in the present detergents.

The spray drying of a silicate-free detergent mixture can result in a relatively dusty, granular product due to the absence of silicate as a binder for the spray-dried beads. However, alternative organic binding materials can be used, such as e.g. starch, carboxymethylcellulose or other comparable materials. The strength of the spray-dried beads can also

is improved by increasing the solids content of the silicate-free slurry in the mill to a maximum and/or by maintaining the inlet temperature for the hot air flow into the spray tower as low as possible.

The bleaching agent can be mixed directly with the spray-dried powder or the bleaching agent and the possible sequestering agent can be separately or collectively coated with a coating material to prevent premature activation of the bleaching agent. The coating process is carried out using methods that are well known in the state of the art. Suitable coating materials include such compounds as magnesium sulfate, polyvinyl alcohol, lauric acid or its salts, etc.

The bleaching detergents according to the invention are added to the washing solution in a sufficient amount so that the solution contains 3-100 parts of active oxygen per parts per million of the solution, and a concentration of 3-40 ppm is generally preferred.

The particulate bleaching detergents described above can be produced using such methods as spray drying, dry mixing or agglomeration of the individual components.

Example 1

A preferred silicate-free bleaching detergent consists of the following components:

The above product is produced by spray drying

of an aqueous slurry containing 60% by weight of a mixture of all the above components, except the enzyme, the perfume, the TAED and the sodium perborate. The resulting particulate, spray-dried product has a particle size in the range of 14-270 mesh (U.S. sieve standard). The spray-dried product is then mixed in a rotating drum with the appropriate amounts of sodium perborate of similar particle size, TAED, enzyme and perfume to obtain a particulate product with a moisture content of approx. 18% by weight.

The product described above is used to wash soiled clothes by hand and also in an automatic washing machine,

and good washing and bleaching results are achieved with both washing methods.

Other satisfactory products can be obtained by varying the concentrations of the following main components in the recipe described above, as follows:

For a highly concentrated coarse washing powder, the alkyl benzene sulfonate, TPP and soap component in the recipe described above can be omitted, and the content of ethoxylated alcohol can be increased to an upper limit of 20%.

Example 2

Bleaching tests are carried out as described below to compare the bleaching result with water-soluble, silicate-free, bleaching detergents according to the invention and with corresponding silicate-containing detergents which are comparable to the first in almost all respects except for the presence of a water-soluble silicate compound. More specifically, the silicate-free detergents are characterized by the presence of sodium metaborate, and the silicate-containing detergents contain sodium silicate. The detergents are produced by adding granules of sodium perborate tetrahydrate and tetraacetylethylenediamine (TAED) to a spray-dried, particulate detergent mixture to form the bleaching detergents shown in Table 1 below. The numbers given in the table represent the percentage by weight of each component in the detergent .

Test method

Bleaching tests were carried out in an Ahiba type apparatus at the highest temperatures of 60°C and 90°C, as described below. 600 ml tap water with a hardness of approx. 320 ppm, as calcium carbonate, is filled into each of six buckets in the Ahiba apparatus. Six cotton cloths (8 cm x 12 cm) soiled with immedial black were introduced into each bucket, and the original reflectance from each cloth was measured with a Gardner XL 20 reflectance meter.

6 g of each of the detergents A-F indicated in table 1 are introduced separately into the six buckets in the Ahiba apparatus, with a different detergent being introduced into each bucket. The bleaching detergents are carefully mixed in each bucket using a mixer, and the wash cycle is then started. The washing bath temperature, which is originally 30°C, may increase by approx. 1°C per minute until the maximum test temperature (60°C or 90°C) has been reached, and this maximum temperature is then maintained for approx. 15 minutes. The buckets are then removed, and each cloth is washed twice with cold water and dried.

The final reflectance from the cloths is measured, and the difference (A Rd) between the final and original reflectance values is determined. An average value of A Rd for the six cloths in each bin is then calculated. The results of the bleaching tests are reproduced in Table 2 below, with the values for A Rd being an average value ■^ or the specially specified detergent and the specially specified test.

As indicated in table 2, they provide silicate-free detergents

(A, B and C) improved bleaching results compared to the silicate-containing detergents at both test temperatures. Among the silicate-containing detergents, the one containing 1% EDITEMPA (F) gives an improved bleaching effect compared to the detergent D which does not contain a sequestering agent, but only at the high test temperature of 90°C. At both test temperatures, however, the silicate-free detergent A, which does not contain a sequestering agent, gives the best bleaching effect of all the detergents examined.

Example 3

The concentration of active oxygen in solution is determined as a function of time for washing the solutions containing each of the detergents A-F described in Table 1. The test method is as follows: 1 liter of tap water is introduced into a 2 liter beaker and then heated to a constant temperature of 60°C in a water bath. 10 g of the particulate detergent under investigation is added to the beaker (time = 0) with careful mixing to form a uniform washing solution. After given time periods (5, 15, 30, 45 and 60 minutes), a 50 ml aliquot is removed from the washing solution, and the concentration of total active oxygen is determined by the method specified below.

B determination of concentration of total active 0^

The above 50 ml aliquot is poured into a 300 ml Erlenmeyer flask fitted with a ground stopper and containing 15 ml of a sulfuric acid/molybdate mixture which has been prepared in bulk by dissolving 0.18 g of ammonium molybdate in 750 ml

deionized water and then adding 320 mL of H„SO.

2 4

(approx. 36N) with stirring. The solution in the Erlenmeyer flask is carefully mixed, and 5 ml of a 10% Kl solution in deionized water is added to this. The Erlenmeyer flask is closed with a stopper, agitated and then allowed to stand in a dark place for 7 minutes. The solution in the flask is then titrated with a solution of 0.1 N sodium thiosulfate in deionized water. The required volume of thiosulphate,

in ml, is equal to the concentration of total active oxygen, in millimoles/litre, in the washing solution. The test results for the six investigated detergents are reproduced in table 3 below.

As shown in table 3, the silicate-free detergents

agents A, B and C are significantly more stable and are characterized by a much slower loss of active oxygen from the solution than the corresponding silicate-containing detergents or D, E and F. Among the silicate-containing detergents are those that contain

1% EDITEMPA (F) is what gives the greatest stability, but such a detergent is less stable than all of the silicate-free detergents, including detergent A which does not contain a sequestering agent. Among the silicate-free detergents, the presence of a sequestering agent in detergents B and C leads to improved oxygen stability • compared to detergent A.

Example 4

Bleaching tests are carried out in an Ahiba apparatus, as indicated below, to compare the bleaching result with a bleaching detergent free of water-soluble silicates in accordance with the invention (B) and the bleaching result obtained with a water-soluble silicate-containing detergent

(A) • As indicated below, the two detergents are comparable in almost all respects except for the presence of sodium silicate in detergent A. A crystalline zeolite material is present in both detergents. The detergents are made by adding particles of sodium perborate tetrahydrate and tetraacetylethylenediamine (TAED) to a particulate detergent mixture formed from an aqueous slurry dried on a steam dryer (a method equivalent to spray drying) to form the bleaching detergent shown in Table 4 below The figures given in the table represent the percentage by weight of each component in the detergent. The bleaching test is carried out in accordance with the test method indicated in example 2, and the results of such a test are reproduced in the table 5 below. The values for ARd are given as an average value for the specified test.

As indicated in Table 5, the detergent B, which is free of water-soluble silicate, gives a significantly improved bleaching compared to the silicate-containing detergent A.

Claims (16)

1. Particulate, bleaching detergent, characterized in that it comprises (a) a bleaching agent comprising a peroxygen compound in combination with an activator for this, and (b) at least one surface-active agent from the group of anionic, cationic, non-ionic, ampholytic and zwitterionic detergents, the bleaching detergent being essentially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise a mixture of the activator, a water-insoluble silicate compound and a non-ionic surfactant. 2. Detergent according to claim 1, characterized in that it also contains a sequestering agent. 3. Detergent according to claim 2, characterized in that the sequestering agent contains ethylenediaminetetraacetic acid and/or a water-soluble salt thereof. 4. Detergent according to claim 2, characterized in that the sequestering agent comprises diethylenetriaminepentamethylenephosphonic acid and/or a water-soluble salt thereof. 5. Detergent according to claims 1-4, characterized in that it is essentially free of sequestering agents with a stability constant above approx. 20 for Cu <2+-> complexation in water at 25°C and an ionic strength of 0.1 mol litre. 6. Detergent according to claims 1-5, characterized in that the bleaching agent comprises an alkali metal perborate in combination with tetraacetylethylenediamine (TAED). 7. Detergent according to claim 6, characterized in that the tetraacetylethylene diamine is contained in granules in combination with a mixture of sodium and potassium triphosphate. 8. Detergent according to claim 6 or 7, characterized in that the tetraacetylethylenediamine has the following particle size distribution: 0-20% greater than 150yUm, 10-100% greater than lOO^um but less than 150yU m, 0-50% less than 75yum and 0-20% less than 50yU m. 9. Detergent according to claim 6 or 7, characterized in that approx. 50% of the particles of tetraacetylethylenediamine have a size above 160 yum. 10. Detergent according to claims 1-9, characterized in that at least 80% by weight of the agglomerate particles is made up of the aforementioned mixture. 11. Detergent according to claims 1-10, characterized in that it also contains a detergent builder salt. 12. Detergent according to claim 11, characterized in that the building salt is a zeolite. 13. Detergent according to claims 1-12, characterized in that the surfactant is an anionic cleaning agent. 14. Detergent according to claim 13, characterized in that the anionic cleaning agent is a linear alkylbenzene sulphonate. 15. Detergent according to claims 1-14, characterized in that it also contains a bentonite clay. 16. Detergent according to claims 1-15, characterized in that it comprises (a) 1-50% by weight of a bleaching agent comprising a peroxygen compound in combination with an activator thereof, (b) 5-50% by weight of a surface-active cleaning agent from the group of anionic, cation-active, non-ionic, ampholytic and zwitterionic cleaning agents, (c) 1-60% by weight of a detergent builder salt, (d) 0.1-10% by weight of a sequestering agent and (e) the remainder water and optionally a filler salt, the detergent being essentially free of (i) water-soluble silicate compounds and (ii) agglomerate particles which essentially comprise a mixture of the activator, a water-insoluble silicate compound and a non-ionic surfactant medium.