WO2009135765A1 - Process to manufacture a liquid laundry detergent composition - Google Patents

Abstract

A process for the manufacture of a structured liquid detergent composition comprising: a) at least 0.00005%wt, preferably 0.05-10%wt, of a disperse-phase benefit agent, b) 0.025- 0.2%wt, of micro-fibrous cellulose, c) less than l%vol incorporated air, and, d) at least 5%wt of anionic surfactant and 25 to 55%wt surfactant, the process comprising the steps of (i) preparation of a micro-fibrous cellulose premix, at a concentration of 0.1-2.5%wt, preferably 0.1- 2%wt, using high shear mixing, preferably under conditions which generate a liquid velocity of greater than 3 m.s^-1, (ii) separate preparation of an aqueous surfactant mix comprising less than l%wt of incorporated air, and the bulk of the water in the composition, (iii) combination of the micro-fibrous cellulose premix and the surfactant mix using high shear mixing, preferably under conditions which generate a liquid velocity of greater than 3 m.s^-1 and maintaining the air content below l%vol at least during gel formation.

Description

PROCESS TO MANUFACTURE A LIQUID LAUNDRY DETERGENT

COMPOSITION

Field of the Invention

This invention relates to a process for the manufacture of liquid laundry detergent compositions.

Background of the Invention

Many laundry detergent liquids are clear, isotropic liquids with an approximately Newtonian (i.e. shear rate independent) viscosity profile. Dispersed-phase benefit agents, for example in the form of encapsulated materials such as encapsulated perfume, dispersed droplets of, for example, silicone antifoam may not interact with the product, but it is difficult to incorporate these materials in a stable product, as they can, for example, either "cream" or sediment. In order to suspend droplets and particles, such as those including benefit agents, the low/zero shear viscosity of products must typically be high and the liquid must possess a critical stress. However, to be dispensed by pouring, a low viscosity at intermediate shear rates is required. Therefore, to maintain a dispersed phase in suspension, a shear-thinning rheology is preferred, ideally in combination with a moderate critical stress for the onset of this low viscosity region. Thus, a purely Newtonian liquid allows little scope for product differentiation, particularly as regards the incorporation of dispersed benefit agents in the product.

There is therefore a need to develop versatile structuring routes that allow the suspension of, for example, perfume encapsulates. This is particularly true in applications relating to so-called "3X" and higher "super-concentrated" fabric washing liquids, as many conventional thickening systems cannot be formulated well, if at all, at high surfactant concentrations.

US patent application US2007/0197779 (CP Kelco, published August 23^rd, 2007) discloses a structurant consisting of bacterially produced micro-fibrous cellulose combined with carboxy methyl cellulose and xanthan gum as dispersion aids. Upon high shear dispersion in water, the micro-fibrous cellulose forms a 3-D network structure, which can suspend inert materials such as sand and nylon beads. However, practical difficulties arise when this type of thickening agent is used with surfactant containing compositions.

Summary of the Invention

We have determined that effective thickening by micro- fibrous cellulose (MFC) can be obtained provided that the incorporated air content of the liquid is below l%vol. Accordingly, the present invention provides a process for the manufacture of a structured liquid detergent composition comprising: a) at least 0.00005%wt, preferably 0.05-10%wt, of a disperse-phase benefit agent, b) 0.025- 0.2%wt, of micro-fibrous cellulose, c) less than l%vol, preferably less than 0.8%vol, most preferably less than 0.5%vol incorporated air, and, d) greater than 5%wt of anionic surfactant and a total surfactant concentration of 25 to 55%wt,

the process comprising the steps of:

(i) preparation of a micro-fibrous cellulose premix, at a concentration of 0.1-2.5%wt, preferably 0.1-2%wt, using high shear mixing , preferably under conditions which generate a liquid velocity of greater than 3 m.s^'1, (ii) separate preparation of an aqueous surfactant mix comprising less than l%wt of incorporated air, the surfactant premix comprising the bulk of the water in the composition, and,

(iii) combination of the micro-fibrous cellulose premix and the surfactant mix using high shear mixing, preferably under conditions that generate a liquid velocity of greater than 3 m.s^'1.

By separately forming a premix of the micro-fibrous cellulose and a surfactant premix comprising the bulk of the water and a low level of air, and combining these pre-mixes using intensive shear, it is possible to obtain a stable product which does not show separation on storage. Moreover, employing the bulk of the water in the preparation of the surfactant-containing process stream makes formulation of this process stream more straightforward, avoiding the formation of gel phases and other difficulties.

The mixed surfactant system comprising at least 5%wt anionic surfactant displaces air from the water so it is advantageous that the bulk of the water is already in contact with the surfactant system before the structuring system is introduced.

The high shear mixing step in (iii) above is preferably achieved using an in-line mixing process, such as by contacting the two process streams directly before an inline mixer. A rotor/stator type in-line mixer has been found suitable.

The above process results in good structuring; avoids aeration and permits late structuring if required. Late structuring makes cleaning in place less difficult, allows for more process and product flexibility, especially on existing plant. Late addition of the disperse phase benefit agent is particularly advantageous for product and process flexibility where a range of different products is produced with a single bulk formulation and different benefit agents.

As noted above, the compositions of the present invention comprise 25-55%wt surfactant.

It is believed that aeration of products during production leads to instability due to a froth-flotation mechanism where the air adsorbs to the micro-fibrous cellulose then floats regions of the structural network leaving behind free isotropic liquid. Severe separation occurs when aeration levels approach 5% by volume but even lower levels (1 to 2% by volume) deplete the fibre network. Finer bubbles are believed to be more damaging. The level of incorporated air in the composition should thus be kept to a maximum of 1% by volume, but desirably it is even lower, preferably less than 0.8%vol or more preferably less than 0.5%vol. The separation is typically observed as a clear layer forming at the base of samples although clear patches can also appear in the bulk. The solubility of air in pure water (at 25C and IATM) is around 1.9%vol, hence for products containing around 50% water any additional air has the potential to form bubbles, moreover, when surfactant is present, the solubility of air is lower and air may be displaced from solution to form fine bubbles.

Compositions manufactured according to the invention advantageously exhibit the desired shear-thinning properties. Preferred compositions according to the invention exhibit (at 25 Celsius) a viscosity of below 1

Pa. s at a shear stress of above 10 Pa and a viscosity above 1 Pa. s at a shear stress below 0.1 Pa. Preferably the composition is translucent and more preferably it is transparent.

Preferably, the benefit agent is an encapsulated benefit agent, more preferably an encapsulated perfume.

The skilled worker will be aware of suitable methods to measure the level of incorporated air. One such suitable method uses a Pycnometry based density measurement method comprising the following methodology.

1) Fill a cylindrical pycnometer (volume 38.24cm³) with ^λaerated' laundry liquid. Ensure the liquid fill level corresponds to the pre-defined pycnometer volume. The fluid meniscus should be small as the surface tension will be low for a surfactant containing liquid.

2) Measure the weight of the fluid, by subtracting the weight of the pycnometer from the gross weight of the pycnometer and the fluid.

3) The density is then calculated through the simple relation Mass/ Volume (Kg/ m³)

4) Remove the air from the formulation using centrifugation . A centrifugal acceleration of 300 X (the standard acceleration of gravity, g) for 30 seconds should be sufficient to remove all the air.

5) Repeat steps 1) to 3) to calculate the density of the ^λair free' formulation.

6) The difference between the two densities provides a measure of the %vol incorporated air.

7) Although the density of these systems is relatively insensitive to temperature, measurements should be made under the same conditions. Detailed Description of the Invention

In order that the present invention can be further understood, it is described below with reference to various preferred features.

Micro-fibrous Cellulose:

Micro-fibrous celluloses suitable for use in the present invention include those described in US 2007/019779 (CP

Kelco) . Particular preferred materials are those obtained from Acetobacter. These materials are available in the marketplace from CP Kelco (Atlanta, Georgia USA) .

Dispersed Phase:

The disperse phase benefit agent can be present in the form of solid particles or liquid droplets. Preferably, the benefit agent is present as solid particles and more preferably, the particles comprise a carrier or encapsulant as well as the benefit agent.

While it is preferred to use polymer particles, preferably core-shell encapsulates, many other types of particle can be envisaged as the carrier. Benefit agents, such as perfumes have been adsorbed onto a clay or zeolite material that is then admixed into particulate detergent compositions: U.S. Pat. No. 4,539,135 discloses particulate laundry compounds comprising a clay or zeolite material carrying perfume. Other perfume delivery systems are taught by WO 97/34982 and WO 98/41607, published by The Procter & Gamble. WO 97/34982 discloses particles comprising perfume loaded zeolite and a release barrier, which is an agent derived from a wax and having a size (i.e., a cross-sectional area) larger than the size of the pore openings of the zeolite carrier. WO 98/41607 discloses glassy particles comprising agents useful for laundry or cleaning compositions and a glass derived from one or more of at least partially-water-soluble hydroxylic compounds.

Silicas, amorphous silicates, crystalline nonlayer silicates, layer silicates, calcium carbonates, calcium/sodium carbonate double salts, sodium carbonates, sodalites, alkali metal phosphates, pectin, chitin microbeads, carboxyalkylcelluloses, gums, resins, gelatin, gum arabic, porous starches, modified starches, carboxyalkyl starches, cyclodextrins, maltodextrins, synthetic polymers such as polyvinyl pyrrolidone (PVP) , polyvinyl alcohol (PVA) , cellulose ethers, polystyrene, polyacrylates, polymethacrylates, polyolefins, aminoplast polymers, crosslinkers and mixtures thereof can all provide a basis for perfume particles.

Aminoplast core-shell particles are particularly preferred.

Suitable particle sizes for the benefit agent range from nanometre scale to micron scale and even to millimetre scale. Typical particle sizes range from 1 micron to 1 mm, with, for encapsulated perfumes, particle sizes in the range of 5-50 microns being preferred, especially particles of 10- 30 microns. In preferred embodiments herein, encapsulated benefit agent (particularly perfume) leaves little or no visible residues on fabrics onto which it is deposited. Larger particles can be employed in the form of functional, but visible "beads", typically of a size range of 0.1-5mm.

Particulate benefit agents are preferably provided with a deposition aid. A deposition aid can be incorporated in the shell of an encapsulated benefit agent. The deposition aid is preferably attached to the particle by means of a covalent bond, entanglement or strong adsorption, preferably by a covalent bond or entanglement and most preferably by means of a covalent bond. By entanglement as used herein is meant that the deposition aid is for example adsorbed onto the particle as polymerisation proceeds and the particle grows in size, part of the adsorbed deposition aid becomes buried within the interior of the particle. The deposition aid can be nonionic, cationic or anionic.

In one preferred embodiment, the deposition aid is a polysaccharide. In these embodiments the polysaccharide preferably has a β-l,4-linked backbone and is substantive to cellulose .

Preferably, the polysaccharide is cellulose, a cellulose derivative, or another β-l,4-linked polysaccharide having an affinity for cellulose, such as polymannan, polyglucan, polyglucomannan, polyxyloglucan and polygalactomannan or a mixture thereof. More preferably, the polysaccharide is selected from the group consisting of polyxyloglucan and polygalactomannan. For example, preferred polysaccharides are locust bean gum, tamarind xyloglucan, guar gum or mixtures thereof. Most preferably, the deposition aid is locust bean gum.

Benefit Agents:

The present invention may be applied with any of the benefit agents used in fabric treatment. The benefit agent is preferably selected from, antifoams, softening agents, finishing agents/protective agents and, most especially, perfumes.

Examples of softening agents are clays, cationic surfactants or silicone compounds. Examples of finishing agents/protective agents are lubricants, soil repelling agents, soil release agents, photo-protective agents (sunscreens) , anti-static agents, dye-fixing agents, whitening agents, including fluorescer, anti-bacterial agents and anti-fungal agents. Other benefit agents include insect repellents and/or pheromones.

So-called "shading dyes" are a further useful benefit agent. These deposit on the cloth to give a hue, which counteracts the effects of yellowing, and give an impression of whiteness. Typically, shading dye will be present at 0.00001 wt% to 0.0010 wt% of the formulation.

Other useful benefit agents include encapsulated enzymes and antifoams. Typical levels of encapsulated benefit agent are 0.01-10%. Un-encapsulated benefit agents such as particles of shading dyes may be present at even lower levels. Perfume :

The benefit agent is most preferably a perfume, which is typically present in an amount of from 10-85% by total weight of the particle, preferably from 20 to 75 % by total weight of the particle. The perfume suitably has a molecular weight of from 50 to 500.

Useful components of the perfume include materials of both natural and synthetic origin. They include single compounds and mixtures. Specific examples of such components may be found in the current literature, e.g., in Fenaroli's Handbook of Flavor Ingredients, 1975, CRC Press; Synthetic Food Adjuncts, 1947 by M. B. Jacobs, edited by Van Nostrand; or Perfume and Flavor Chemicals by S. Arctander 1969,

Montclair, N.J. (USA) . These substances are well known to the person skilled in the art of perfuming, flavouring, and/or aromatizing consumer products, i.e., of imparting an odour and/or a flavour or taste to a consumer product traditionally perfumed or flavoured, or of modifying the odour and/or taste of said consumer product.

By perfume in this context is not only meant a fully formulated product fragrance, but also selected components of that fragrance, particularly those that are prone to loss, such as the so-called ^λtop notes' . The perfume component could also be in the form of a profragrance . WO 2002/038120 (P&G), for example, relates to photo-labile pro-fragrance conjugates, which upon exposure to electromagnetic radiation are capable of releasing a fragrant species. Top notes are defined by Poucher (Journal of the Society of Cosmetic Chemists 6(2) : 80 [1955]) . Examples of well known top-notes include citrus oils, linalool, linalyl acetate, lavender, dihydromyrcenol, rose oxide and cis-3-hexanol . Top notes typically comprise 15-25%wt of a perfume composition and in those embodiments of the invention which contain an increased level of top-notes it is envisaged at that least 20%wt would be present within the encapsulate. Typical perfume components that it is advantageous to encapsulate include those with a relatively low boiling point, preferably those with a boiling point of less than 300, preferably 100-250 Celsius.

It is also advantageous to encapsulate perfume components which have a low LogP (i.e. those which will be partitioned into water), preferably with a LogP of less than 3.0. These materials, of relatively low boiling point and relatively low LogP have been called the "delayed blooming" perfume ingredients and include the following materials:

Allyl Caproate, Amyl Acetate, Amyl Propionate, Anisic Aldehyde, Anisole, Benzaldehyde, Benzyl Acetate, Benzyl Acetone, Benzyl Alcohol, Benzyl Formate, Benzyl Iso Valerate, Benzyl Propionate, Beta Gamma Hexenol, Camphor Gum, Laevo-Carvone, d-Carvone, Cinnamic Alcohol, Cinamyl Formate, Cis-Jasmone, cis-3-Hexenyl Acetate, Cuminic Alcohol, Cyclal C, Dimethyl Benzyl Carbinol, Dimethyl Benzyl Carbinol Acetate, Ethyl Acetate, Ethyl Aceto Acetate, Ethyl Amyl Ketone, Ethyl Benzoate, Ethyl Butyrate, Ethyl Hexyl

Ketone, Ethyl Phenyl Acetate, Eucalyptol, Eugenol, Fenchyl Acetate, Flor Acetate (tricyclo Decenyl Acetate) , Frutene (tricyclco Decenyl Propionate), Geraniol, Hexenol, Hexenyl Acetate, Hexyl Acetate, Hexyl Formate, Hydratropic Alcohol, Hydroxycitronellal, Indone, Isoamyl Alcohol, Iso Menthone, Isopulegyl Acetate, Isoquinolone, Ligustral, Linalool, Linalool Oxide, Linalyl Formate, Menthone, Menthyl Acetphenone, Methyl Amyl Ketone, Methyl Anthranilate, Methyl Benzoate, Methyl Benzyl Acetate, Methyl Eugenol, Methyl Heptenone, Methyl Heptine Carbonate, Methyl Heptyl Ketone, Methyl Hexyl Ketone, Methyl Phenyl Carbinyl Acetate, Methyl Salicylate, Methyl-N-Methyl Anthranilate, Nerol, Octalactone, Octyl Alcohol, p-Cresol, p-Cresol Methyl Ether, p-Methoxy Acetophenone, p-Methyl Acetophenone, Phenoxy Ethanol, Phenyl Acetaldehyde, Phenyl Ethyl Acetate, Phenyl Ethyl Alcohol, Phenyl Ethyl Dimethyl Carbinol, Prenyl

Acetate, Propyl Bornate, Pulegone, Rose Oxide, Safrole, 4- Terpinenol, Alpha-Terpinenol, and /or Viridine.

It is commonplace for a plurality of perfume components to be present in a formulation. In the encapsulates of the present invention it is envisaged that there will be four or more, preferably five or more, more preferably six or more or even seven or more different perfume components from the list given of delayed blooming perfumes given above present in the encapsulated perfume.

Part or all of the perfume may be in the form of a pro- fragrance. For the purposes of the present invention, a pro-fragrance is any material that comprises a fragrance precursor that can be converted into a fragrance. Suitable pro-fragrances are those that generate perfume components, which are aldehydes. Aldehydes useful in perfumery include but are not limited to phenylacetaldehyde, p-methyl phenylacetaldehyde, p-isopropyl phenylacetaldehyde, methyinonyl acetaldehyde, phenylpropanal, 3- (4-t- butylphenyl) -2 -methyl propanal, 3- (4-t-butylphenyl) - propanal, 3- (4-methoxyphenyl) -2-methylpropanal, 3- (4- isopropylphenyl) -2- methylpropanal, 3- (3, 4- methylenedioxyphenyl) -2-methyl propanal, 3- (4- ethylpheny) - 2, 2-dimethylpropanal, phenylbutanal, 3-methyl-5- phenylpentanal, hexanal, trans-2-hexenal, cis-hex-3-enal, heptanal, cis-4-heptenal, 2-ethyl-2- heptenal, 2, 6-dimethyl- 5-heptenal, 2, 4-heptadienal, octanal, 2-octenal, 3,7- dimethyloctanal, 3, 7-dimethyl-2, 6-octadien-l-al, 3,7- dimethyl-1, 6-octadien-3-al, 3, 7-dimethyl-6-octenal, 3,7- dimethyl-7-hydroxyoctan-l-al, nonanal, 6-nonenal, 2,4- nonadienal, 2, 6-nonadienal, decanal, 2-methyl decanal, 4- decenal, 9- decenal, 2, 4-decadienal, undecanal, 2- methyldecanal, 2-methylundecanal, 2, 6, 10-trimethyl-9- undecenal, undec-10-enyl aldehyde, undec-8-enanal, dodecanal, tridecanal, tetradecanal, anisaldehyde, bourgenonal, cinnamic aldehyde, a-amylcinnam-aldehyde, a- hexyl cinnamaldehyde, methoxy- cinnamaldehyde, citronellal, hydroxy-citronellal, isocyclocitral, citronellyl oxyacet- aldehyde, cortexaldehyde, cumminic aldehyde, cyclamen aldehyde, florhydral, heliotropin, hydrotropic aldehyde, lilial, vanillin, ethyl vanillin, benzaldehyde, p- methyl benzaldehyde, 3, 4-dimethoxybenzaldehyde, 3-and 4- (4- hydroxy-4- methyl-pentyl) -3-cyclohexene-l-carboxaldehyde, 2 , 4-dimethyl-3-cyclohexene-l- carboxaldehyde, l-methyl-3- (4-methylpentyl) -3-cyclohexen-carboxaldehyde, p- methylphenoxyacetaldehyde, and mixtures thereof.

Another group of perfumes with which the present invention can be applied are the so-called ^λaromatherapy' materials. These include many components also used in perfumery, including components of essential oils such as Clary Sage, Eucalyptus, Geranium, Lavender, Mace Extract, Neroli, Nutmeg, Spearmint, Sweet Violet Leaf and Valerian. These materials can be transferred to textile articles that will be worn or otherwise come into contact with the human body (such as handkerchiefs and bed-linen) .

The perfume may be encapsulated alone or co-encapsulated with carrier materials, further deposition aids and/or fixatives. Preferred materials to be co-encapsulated with the perfume include waxes, paraffins, stabilizers and fixatives .

An optional yet preferred component of capsule is a formaldehyde scavenger. This is particularly advantageous in capsules that may comprise formaldehyde as a consequence of their manufacturing process or components. Formaldehyde scavenger is chosen from: sodium bisulfite, urea, cysteine, cysteamine, lysine, glycine, serine, carnosine, histidine, glutathione, 3, 4-diaminobenzoic acid, allantoin, glycouril, anthranilic acid, methyl anthranilate, methyl 4- aminobenzoate, ethyl acetoacetate, acetoacetamide, malonamide, ascorbic acid, 1, 3-dihydroxyacetone dimer, biuret, oxamide, benzoguanamine, pyroglutamic acid, pyrogallol, methyl gallate, ethyl gallate, propyl gallate, triethanol amine, succinamide, thiabendazole, benzotriazol, triazole, indoline, sulfanilic acid, oxamide, sorbitol, glucose, cellulose, poly (vinyl alcohol), poly (vinyl amine), hexane diol, ethylenediamine-N, N ' -bisacetoacetamide, N- (2- ethylhexyl) acetoacetamide, N- (3-phenylpropyl) acetoacetamide, lilial, helional, melonal, triplal, 5, 5-dimethyl-l, 3- cyclohexanedione, 2, 4-dimethyl-3-cyclohexenecarboxaldehyde, 2, 2-dimethyl-l, 3-dioxan-4, 6-dione, 2-pentanone, dibutyl amine, triethylenetetramine, benzylamine, hydroxycitronellol, cyclohexanone, 2-butanone, pentane dione, dehydroacetic acid, chitosan, or a mixture thereof. Preferred formaldehyde scavengers are sodium bisulfite, ethyl acetoacetate, acetoacetamide, ethylenediamine-N, N '- bisacetoacetamide, ascorbic acid, 2, 2-dimethyl-l, 3-dioxan- 4, 6-dione, helional, triplal, lilial and mixtures thereof.

Other benefit agents include photo-bleaches and/or other materials that may become activated when the fabric is being dried, e.g. by line drying or tumble drying. Anionic Surfactant:

The laundry detergent compositions of the present invention contain greater than 5% anionic surfactant by weight of the composition.

The anionic surfactants used in this invention can be any anionic surfactant that is water soluble. "Water soluble" surfactants are, unless otherwise noted, here defined to include surfactants which are soluble or dispersible to at least the extent of 0.01% by weight in distilled water at 25⁰C. "Anionic surfactants" are defined herein as amphiphilic molecules with an average molecular weight of less than about 10,000, comprising one or more functional groups that exhibit a net anionic charge when in aqueous solution at the normal wash pH of between 6 and 11. It is preferred that at least one of the anionic surfactants used in this invention be an alkali or alkaline earth metal salt of a natural or synthetic fatty acid containing between 4 and 30 carbon atoms. It is especially preferred to use a mixture of carboxylic acid salts with one or more other anionic surfactants. Another important class of anionic compounds is the water soluble salts, particularly the alkali metal salts, of organic sulfur reaction products having in their molecular structure an alkyl radical containing from about 6 to 24 carbon atoms and a radical selected from the group consisting of sulphonic and sulfuric acid ester radicals. - I i

Preferred anionic surfactants are the alkyl benzene sulfonates of the general formula:

RArSO₃M

where R is an alkyl group of 8 to 18 carbon atoms, Ar is a benzene ring (CeH₄) and M is a solubilising cation. The group R may be a mixture of chain lengths. A mixture of isomers is typically used, and a number of different grades, such as "high 2-phenyl" and "low 2-phenyl" are commercially available for use depending on formulation needs. A plentitude of commercial suppliers exist for these materials, including Stepan (Northfield, 111.) and Witco (Greenwich, Conn.) . Typically, they are produced by the sulfonation of alkylbenzenes, which can be produced by either the HF-catalyzed alkylation of benzene with olefins or an AlCl3-catalyzed process that alkylates benzene with chloroparaffins, and are sold by, for example, Petresa (Chicago, 111.) and Sasol (Austin, Tex.) . Straight chains of 11 to 14 carbon atoms are usually preferred.

Nonionic Surfactant:

For the purposes of this disclosure, "nonionic surfactant" means amphiphilic molecules with a molecular weight of less than about 10,000, which are substantially free of any functional groups that exhibit a net charge at the normal wash pH of 6-11. Any type of nonionic surfactant may be used, although preferred materials are fatty alcohol ethoxylates :

RO (EO) _n

Wherein R represents an alkyl chain of between 4 and 30 carbon atoms, (EO) represents one unit of ethylene oxide monomer and n has an average value between 0.5 and 20. R may be linear or branched. Such chemicals are generally produced by oligomerizing fatty alcohols with ethylene oxide in the presence of an effective amount catalyst, and are sold in the market as, for example, Neodols from Shell (Houston, Tex.) and Alfonics from Sasol (Austin, Tex.) . The fatty alcohol starting materials, which are marketed under trademarks such as Alfol, Lial and Isofol from Sasol

(Austin, Tex.) and Neodol, from Shell, may be manufactured by any of a number of processes known to those skilled in the art, and can be derived from natural or synthetic sources or a combination thereof. Commercial alcohol ethoxylates are typically mixtures, comprising varying chain lengths of R and levels of ethoxylation . Often, especially at low levels of ethoxylation, a substantial amount of unethoxylated fatty alcohol remains in the final product, as well .

Insoluble Matter

It is preferred that the compositions of the present invention are formulated with low levels, if any at all, of any matter other than the benefit agent that is substantially insoluble in the solvent intended to be used to dilute the product. For the purposes of this disclosure, "substantially insoluble" shall mean that the material in question can individually be dissolved at a level of less than 0.001% in the specified solvent. Examples of substantially insoluble matter in aqueous systems include insoluble builders. Preferably, insoluble and substantially insoluble matter will be limited to less than 10% of the composition, more preferably to about 5%. Most preferably, especially in the case of liquid conditioning compositions, the bulk phase of the composition will be essentially free, or have less than about 5%, of substantially insoluble matter or precipitation.

Optional Ingredients

In addition to the above-mentioned essential elements, the formulator may include one or more optional ingredients, which are often very helpful in rendering the formulation more acceptable for consumer use.

Examples of optional components include, but are not limited to: anionic polymers, uncharged polymers, nonionic surfactants, amphoteric and zwitterionic surfactants, cationic surfactants, hydrotropes, fluorescent whitening agents, photobleaches, fiber lubricants, reducing agents, enzymes, enzyme stabilizing agents, powder finishing agents, defoamers, builders, bleaches, bleach catalysts, soil release agents, dye transfer inhibitors, buffers, colorants, fragrances, pro-fragrances, anti-ashing polymers, preservatives, insect repellents, soil repellents, water- resistance agents, suspending agents, aesthetic agents, structuring agents, sanitizers, solvents, fabric finishing agents, dye fixatives, wrinkle-reducing agents, fabric conditioning agents and deodorizers.

Preservatives

Optionally, a soluble preservative may be added. The presence of a preservative is preferred when the composition is a liquid, as these products tend to be especially susceptible to microbial growth.

The use of a broad-spectrum preservative, which controls the growth of bacteria and fungi, is preferred. Limited- spectrum preservatives, which are only effective on a single group of micro-organisms, may also be used, either in combination with a broad-spectrum material or in a "package" of limited-spectrum preservatives with additive activities. Depending on the circumstances of manufacturing and consumer use, it may also be desirable to use more than one broad- spectrum preservative to minimize the effects of any potential contamination.

The use of both biocidal materials, i.e. substances that kill or destroy bacteria and fungi, and biostatic preservatives, i.e. substances that regulate or retard the growth of micro-organisms, may be indicated for this invention . In order to minimize environmental waste and allow for the maximum window of formulation stability, it is preferred that preservatives that are effective at low levels be used. Typically, they will be used only at an effective amount. For the purposes of this disclosure, the term "effective amount" means a level sufficient to control microbial growth in the product for a specified period of time, i.e., two weeks, such that the stability and physical properties of it are not negatively affected. For most preservatives, an effective amount will be between about 0.00001% and about 0.5% of the total formula, based on weight. Obviously, however, the effective level will vary based on the material used, and one skilled in the art should be able to select an appropriate preservative and use level.

Preferred preservatives for the compositions of this invention include organic sulphur compounds, halogenated materials, cyclic organic nitrogen compounds, low molecular weight aldehydes, quaternary ammonium materials, dehydroacetic acid, phenyl- and phenoxy- compounds and mixtures thereof.

Examples of preferred preservatives for use in the compositions of the present invention include: a mixture of about 77% 5-chloro-2-methyl-4-isothiazolin-3-one and about 23% 2-methyl-4-isothiazolin-3-one, which is sold commercially as a 1.5% aqueous solution by Rohm & Haas (Philadelphia, Pa.) under the trade name Kathon; 1,2- benzisothiazolin-3-one, which is sold commercially by Avecia (Wilmington, Del.) as, for example, a 20% solution in dipropylene glycol sold under the trade name Proxel GXL; and a 95:5 mixture of 1,3 bis (hydroxymethyl) -5, 5-dimethyl-2, 4 imidazolidinedione and 3-butyl-2-iodopropynyl carbamate, which can be obtained, for example, as Glydant Plus from Lonza (Fair Lawn, N.J.) .

Fluorescent Whitening Agents

Many fabrics, and cottons in particular, tend to lose their whiteness and adopt a yellowish tone after repeated washing. As such, it is customary and preferred to add a small amount of fluorescent whitening agent, which absorbs light in the ultraviolet region of the spectrum and re-emits it in the visible blue range, to the compositions of this invention, especially if they are combination detergent/fabric conditioner preparations.

Suitable fluorescent whitening agents include derivatives of diaminostilbenedisulfonic acid and their alkali metal salts. Particularly, the salts of 4, 4' -bis (2-anilino4-morpholino- 1 , 3, 5-triazinyl-6-amino) stilbene-2 , 2 ' -disulfonic acid, and related compounds where the morpholino group is replaced by another nitrogen-comprising moiety, are preferred. Also preferred are brighteners of the 4, 4' -bis (2-sulfostyryl) biphenyl type, which may optionally be blended with other fluorescent whitening agents at the option of the formulator. Typical fluorescent whitening agent levels in the preparations of this invention range between 0.001% and 1%, although a level between 0.1% and 0,3%, by mass, is normally used. Commercial supplies of acceptable fluorescent whitening agents can be sourced from, for example, Ciba Specialty Chemicals (High Point, N. C.) and Bayer (Pittsburgh, Pa.) .

Builders

Builders are often added to fabric cleaning compositions to complex and remove alkaline earth metal ions, which can interfere with the cleaning performance of a detergent by combining with anionic surfactants and removing them from the wash liquor. The preferred compositions of this invention contain low levels, if any at all, of builder. Generally, these will comprise less than 10%, preferably less than 7% and most preferably less than 5% by weight of total phosphate and zeolite.

Soluble builders, such as alkali metal carbonates and alkali metal citrates, are particularly preferred, especially for the liquid embodiment of this invention.

Other builders, as further detailed below, may also be used, however. Often a mixture of builders, chosen from those described below and others known to those skilled in the art, will be used. Organic detergent builders can also be used as nonphosphate builders in the present invention. Examples of organic builders include alkali metal citrates, succinates, malonates, fatty acid sulfonates, fatty acid carboxylates, nitrilotriacetates, oxydisuccinates, alkyl and alkenyl disuccinates, oxydiacetates, carboxymethyloxy succinates, ethylenediamine tetraacetates, tartrate monosuccinates, tartrate disuccinates, tartrate monoacetates, tartrate diacetates, oxidized starches, oxidized heteropolymeric polysaccharides, polyhydroxysulfonates, polycarboxylates such as polyacrylates, polymaleates, polyacetates, polyhydroxyacrylates, polyacrylate/polymaleate and polyacrylate/ polymethacrylate copolymers, acrylate/maleate/vinyl alcohol terpolymers, aminopolycarboxylates and polyacetal carboxylates, and polyaspartates and mixtures thereof. Such carboxylates are described in U.S. Patent Nos. 4,144,226, 4,146,495 and 4,686,062. Alkali metal citrates, nitrilotriacetates, oxydisuccinates, acrylate/maleate copolymers and acrylate/maleate/vinyl alcohol terpolymers are especially preferred nonphosphate builders. Soaps can also be used a builders. Typical levels of organic builder are l-15%wt, preferably 3-10%wt.

Phosphates are difficult to formulate into liquid products, and have been identified as potential agents that may contribute to the eutrophication of lakes and other waterways. As such, the preferred compositions of this invention comprise phosphates at a level of less than about 10% by weight, more preferably less than about 5% by weight. The most preferred compositions of this invention are formulated to be substantially free of phosphate builders. Zeolites are insoluble matter, it is advantageous to minimize their level in the compositions of this invention. As such, the preferred formulations contain less than about 10% of zeolite builder, while especially preferred compositions comprise less than about 5% zeolite.

Enzyme Stabilizers When enzymes, and especially proteases, are used in liquid detergent formulations, it is often necessary to include a suitable quantity of enzyme stabilizer temporarily to deactivate it until it is used in the wash. Examples of suitable enzyme stabilizers are well-known to those skilled in the art, and include, for example, borates and polyols such as propylene glycol. Borates are especially suitable for use as enzyme stabilisers because in addition to this benefit, they can further buffer the pH of the detergent product over a wide range, thus providing excellent flexibility.

If a borate-based enzyme stabilization system is chosen, along with one or more cationic polymers that are at least partially comprised of carbohydrate moieties, stability problems can result if suitable co-stabilisers are not used. It is believed that this is the result of borates' natural affinity for hydroxyl groups, which can create an insoluble borate-polymer complex that precipitates from solution either over time or at cold temperatures. Incorporating into the formulation a co-stabilizer, which is normally a diol or polyol, sugar or other molecule with a large number of hydroxyl groups, can ordinarily prevent this. Especially preferred for use as a co-stabilizer is sorbitol, used at a level that is at least about 0.8 times the level of borate in the system, more preferably 1.0 times the level of borate in the system and most preferably more than 1.43 times the level of borate in the system, is sorbitol, which is effective, inexpensive, biodegradable and readily available on the market. Similar materials including sugars such as glucose and sucrose, and other polyols such as propylene glycol, glycerol, mannitol, maltitol and xylitol, should also be considered within the scope of this invention.

Fiber Lubricants

In order to enhance the conditioning, softening, wrinkle- reduction and protective effects of the compositions of this invention, it is often desirable to include one or more fiber lubricants in the formulation. Such ingredients are well known to those skilled in the art, and are intended to reduce the coefficient of friction between the fibers and yarns in articles being treated, both during and after the wash process. This effect can in turn improve the consumer's perception of softness, minimize the formation of wrinkles and prevent damage to textiles during the wash. For the purposes of this disclosure, "fiber lubricants" shall be considered non-cationic materials intended to lubricate fibers for the purpose of reducing the friction between fibers or yarns in an article comprising textiles which provide one or more wrinkle-reduction, fabric conditioning or protective benefit.

Examples of suitable fiber lubricants include functionalized plant and animal-derived oils, natural and synthetic waxes and the like. Such ingredients often have low HLB values, less than about 10, although exceeding this level is not outside of the scope of this invention. Various levels of derivatization may be used provided that the derivatization level is sufficient for the oil or wax derivatives to become soluble or dispersible in the solvent it is used in so as to exert a fiber lubrication effect during laundering of fabrics with a detergent containing the oil or wax derivative .

When the use of a fiber lubricant is elected, it will generally be present as between 0.1% and 15% of the total composition weight.

Bleach Catalyst

An effective amount of a bleach catalyst can also be present in the invention. A number of organic catalysts are available such as the sulfonimines as described in U.S. Patents 5,041,232; 5,047,163 and 5,463,115.

Transition metal bleach catalysts are also useful, especially those based on manganese, iron, cobalt, titanium, molybdenum, nickel, chromium, copper, ruthenium, tungsten and mixtures thereof. These include simple water-soluble salts such as those of iron, manganese and cobalt as well as catalysts containing complex ligands.

Suitable examples of manganese catalysts containing organic ligands are described in U.S. Pat. 4,728,455, U.S. Pat. 5,114,606, U.S. Pat 5,153,161, U.S. Pat. 5,194,416, U.S.

Pat. 5,227,084, U.S. Pat. 5,244,594, U.S. Pat .5, 246, 612,

U.S. Pat. 5,246,621, U.S. Pat. 5,256,779, U.S. Pat.

5,274,147, U.S. Pat. 5,280,117 and European Pat. App . Pub.

Nos. 544,440, 544,490, 549,271 and 549,272. Preferred examples of these catalysts include Mn^IV ₂ (u-O) 2 (1, 4, 7- trimethyl-1, 4, 7-triazacyclononane) 2 (PF₆) 2, Mn^IIΣ ₂ (u-O) 1 (u- OAc) 2 (1,4, 7- trimethyl-1, 4, 7-triazacyclononane) 2 (CIO₄) 2 Mn^IV ₄ (u-0) ₆ (1, 4, 7-triazacyclononane)₄ (CIO₄) ₄, MnⁱⁿMn^IV ₄ (u- 0) i (u-OAc) 2(1,4, 7 -trimethyl-1, 4, 7-triazacyclononane) 2 (ClO₄) 3 Mn^IV(l, 4, 7-trimethyl-l, 4, 7-triazacyclononane) - (OCH₃) 3 (PF₆) , and mixtures thereof. Other metal-based bleach catalysts include those disclosed in U.S. Pat. 4,430,243 and U.S. Pat. 5,114,611. Other examples of complexes of transition metals include Mn gluconate, Mn(CFsSOs) 2, and binuclear Mn complexed with tetra-N-dentate and bi-N-dentate ligands, including [bipy2Mn^IIΣ (u-0) 2Mn^Ivbipy2] - (CIO₄) 3. Iron and manganese salts of aminocarboxylic acids in general are useful herein including iron and manganese aminocarboxylate salts disclosed for bleaching in the photographic colour processing arts. A particularly useful transition metal salt is derived from ethylenediaminedisuccinate and any complex of this ligand with iron or manganese.

Another type of bleach catalyst, as disclosed in U.S. Pat. 5,114,606, is a water soluble complex of manganese (II), (III), and/or (IV) with a ligand which is a non-carboxylate polyhydroxy compound having at least three consecutive C-OH groups. Preferred ligands include sorbitol, iditol, dulsitol, mannitol, xylithol, arabitol, adonitol, meso- erythritol, meso-inositol, lactose and mixtures thereof. Especially preferred is sorbitol.

Other bleach catalysts are described, for example, in European Pat. App . Pub. Nos. 408,131 (cobalt complexes), 384,503 and 306,089 (metallo-porphyrins) , U.S. Pat. 4,728,455 (manganese/multidenate ligand), U.S. Pat.

4,711,748 (absorbed manganese on aluminosilicate) , U.S. Pat. 4,601,845 (aluminosilicate support with manganese, zinc or magnesium salt), U.S. Pat. 4,626,373 (manganese/ligand) , U.S. Pat. 4,119,557 (ferric complex), U.S. Pat. 4,430.243 (Chelants with manganese cations and non-catalytic metal cations), and U.S. Pat. 4,728,455 (manganese gluconates) .

Useful catalysts based on cobalt are described in WO 96/23859, WO 96/23860 and WO 96/23861 and U.S. Pat. 5,559,261. WO 96/23860 describe cobalt catalysts of the type [ Co_nL_1nXp ] ^ZY_Z , where L i s an organic l igand molecule containing more than one heteroatom selected from N, P, O and S; X is a co-ordinating species; n is preferably 1 or 2 ; m is preferably 1 to 5; p is preferably 0 to 4 and Y is a counterion. One example of such a catalyst is N, N'- Bis (salicylidene) ethylenediaminecobalt (II) . Other cobalt catalysts described in these applications are based on Co(III) complexes with ammonia and mono-, bi-, tri- and tetradentate ligands such as [Co (NH₃) ₅0Ac] ²⁺ with Cl^", OAc^", PFε^", SO4^", and BF₄ ^" anions.

Certain transition-metal containing bleach catalysts can be prepared in the situ by the reaction of a transition-metal salt with a suitable chelating agent, for example, a mixture of manganese sulfate and ethylenediaminedisuccinate . Highly colored transition metal-containing bleach catalysts may be co-processed with zeolites to reduce the colour impact.

When present, the bleach catalyst is typically incorporated at a level of about 0.0001 to about 10% by wt . , preferably about 0.001 to about 5% by weight. Hydrotropes

In many liquid and powdered detergent compositions, it is customary to add a hydrotrope to modify product viscosity and prevent phase separation in liquids, and ease dissolution in powders.

Two types of hydrotropes are typically used in detergent formulations and are applicable to this invention. The first of these are short-chain functionalized amphiphiles.

Examples of short-chain amphiphiles include the alkali metal salts of xylenesulfonic acid, cumenesulfonic acid and octyl sulphonic acid, and the like. In addition, organic solvents and monohydric and polyhydric alcohols with a molecular weight of less than about 500, such as, for example, ethanol, isoporopanol, acetone, propylene glycol and glycerol, may also be used as hydrotropes.

EXAMPLES:

The following examples will more fully illustrate the embodiments of this invention. All parts, percentages and proportions referred to herein and in the appended claims are by weight unless otherwise illustrated. Physical test methods are described below.

The following materials were used in the examples:

Example 1 : Preparation of MFC premix :

A batch mixer with an external recirculation loop comprising an in-line dynamic mixer was used to prepare a premix of 1% w/w micro-fibrous cellulose (as received) with 0.8%w/w Proxel (as received) in 98.2 demin water. The trials were conducted using a 2 to 3 litre batch mixer agitated by a two or three stage paddle driven by an overhead stirred (Heidolph™ drive) . The paddles had an agitator to tank diameter ratio of 0.5-0.8. Liquid was pumped through the recycle loop by a peristaltic pump at ~1 litre/min. The inline rotor-stator mixer used was an in-line Silverson™ machine driven by a L4RT variable speed drive (operated at a speed of 8000 - 10000 rpm) .

Prior to addition of any MFC, water was re-circulated through the mixer to displace all air (at a flow rate of 20 batch volumes per hour at lab scale) . The MFC powder was sprinkled slowly over five minutes on the surface with paddle agitation and recycling through the mixer. Mixing was continued until the mixture was homogeneous (typically 15 minutes, i.e. 5 batch turnovers) .

Example 2 : Preparation of surfactant premix :

A composition was prepared with the following formulation

The composition was prepared in a paddle-stirred batch mixer at ambient temperature. The product obtained was an isotropic liquid. The product was left to stand for >24hours in order for the incorporated air level to fall below l%vol .

Example 3 : Combination of premixes :

Samples were prepared by use of an apparatus identical to that of Example 1 except that a second peristaltic pump was added to introduce the fibre premix (as prepared in Example 1) in-line just ahead of the high shear mill (Silverson) . Five parts of the product of Example 1 was added to the surfactant pre-mix of Example 2 over a period of three minutes. The operating condition as regards mill speed etc were as in Example 1. Mixing was continued for 15 minutes after the addition of the micro-fibrous cellulose pre-mix.

Example 4: Post dosing of components:

Perfume encapsulates (Amberfresh, ex IFF) were added to 25Og aliquots of the liquid composition resulting from Example 3 at a dosage of 1.5%wt. Addition was performed over 30secs, using a Heidolph stirrer, mixing continued for 5mins (if required) .

Example 5: Storage stability:

Samples prepared from de-aerated premixes were stored at room temperature and 37 Celsius for several weeks. The results are shown in the table below. It can be seen that improved stability was found at a level of >0.025wt% fibres

Claims

CLAIMS :

1. A process for the manufacture of a structured liquid detergent composition comprising: a) at least 0.00005%wt, preferably 0.05-10%wt, of a disperse-phase benefit agent, b) 0.025- 0.2%wt, of micro-fibrous cellulose, c) less than l%vol incorporated air, and, d) at least 5%wt of anionic surfactant and 25 to 55%wt surfactant, the process comprising the steps of

(i) preparation of a micro-fibrous cellulose premix, at a concentration of 0.1-2.5%wt, preferably 0.1- 2%wt, using high shear mixing , preferably under conditions which generate a liquid velocity of greater than 3 m.s^'1,

(ii) separate preparation of an aqueous surfactant mix comprising less than l%wt of incorporated air, and the bulk of the water in the composition, (iii) combination of the micro-fibrous cellulose premix and the surfactant mix using high shear mixing, preferably under conditions which generate a liquid velocity of greater than 3 m.s^'1 and maintaining the air content below l%vol at least during gel formation.

2. A process according to claim 1, which further comprises the step of adding a dispersed phase benefit agent.

3. A process according to claim 1 or 2 in which the composition exhibits (at 25 Celsius) a viscosity of below 1 Pa. s at a shear stress of above 10 Pa and a viscosity above 1 Pa. s at a shear stress below 0.1 Pa.

4. A process according to any preceding claim wherein the composition is transparent.

5. A process according to any preceding claim wherein the benefit agent is an encapsulated benefit agent.

6. A process according to claim 5 wherein the benefit agent is a perfume.

7. A process according to claim 5 wherein the benefit agent comprises a deposition aid.

8. A process according to any preceding claim in which the amount of incorporated air in the composition is less than 0.8%vol, preferably less than 0.5%vol.