EP3060639A1 - Process to manufacture an externally structured isotropic aqueous detergent liquid - Google Patents

Abstract

The present invention relates to a process of manufacturing an externally structured aqueous detergent liquid formulation the process comprising the steps of forming a premix of citrus fibre and water swellable clay powder followed by passing the premix of citrus fibre and water swellable clay powder through a high pressure homogeniser to form a structuring homogenised premix, followed by the addition of at least 2 weight % surfactant and the addition of at least 0.001 weight % non-clay solid particles to form an externally structured liquid formulation.

Description

PROCESS TO MANUFACTURE AN EXTERNALLY STRUCTURED ISOTROPIC AQUEOUS DETERGENT LIQUID

Technical Field of the invention

The present invention relates to a process of manufacturing an externally structured aqueous detergent liquid, a structured homogenised premix of clay powder and citrus fibre for use in the process and an externally structured aqueous detergent liquid resulting prepared using the structured homogenised premix.

Background of the invention

Isotropic liquid detergent compositions have no innate ability to suspend solid particles, for example cues and encapsulates. Whilst it is possible to obtain a suspending medium by appropriate manipulation of the surfactant and electrolyte levels, such processes impose undesirable constraints on the composition. This has lead to the use of so-called external 'structurants', through which it is now possible to achieve the required suspending duty without imposing limiting constraints on the levels of the components in the composition.

The term 'external' used herein in relation to structurants refer to reagents which may be added to a formulation whilst maintaining the desired fluid properties of a detergent liquid. This is in contrast to 'internal' structurants which structure detergent liquids from within using for example electrolytes or salts and which lead to the formation of a lamellar phase or "gel" which may suspend solid particles. Whilst the use of internal structurants may be a cost effective way of creating suspending properties for particles within a detergent, such formulations often possess a viscosity which is too high, resulting in the need for rheology modifiers. In contrast, it is often preferred to use reagents which may be added to a formulation "externally" whilst maintaining the fluid properties.

There are numerous structurants employed in detergent applications. One example of an external structurant is citrus fibre. Compositions comprising citrus fibre and the use of same in foodstuffs and personal care compositions are described in

US2004/0086626 and US2009/269376. ln addition, the compatibility of an activated citrus fibre structured liquid detergent composition with cleaning and care enzymes is described in WO 2012/052306. The use of citrus fibre in combination with a cationic deposition polymer (Jaguar

quaternised guar gum) for anti-dandruff shampoo is also disclosed in WO2012/019934. US 7981855 discloses detergent liquid surfactant compositions comprising up to 15 weight % surfactant, including at least 1 weight % anionic surfactant, up to 2 weight % bacterial cellulose (preferably MFC) and from 0.001 to 5 weight % citrus fibres.

Unfortunately, disadvantages exist when using activated citrus fibre as a structurant for detergent formulations, especially when used at sufficiently high yield strength levels to suspend solid particles as this may lead to the retention of residues on containers when for example a liquid composition is poured from a container. In addition it is often impossible to obtain the required levels of stability in a composition when using citrus fibres alone as the external structurant without over-processing the citrus pulp fibres.

Another known system for suspending solid particles is a combination of clay and a rheology modifying polymer, as disclosed in EP1402877 (Rohm and Haas) and

Research Disclosure, June 2000, No. 434, pages 1032-1033. Clay has been used previously in detergent formulations in liquid form as clay sol. Clay sol differs from clay powder in that the clay is pre-dispersed and usually stabilized with additional ingredients proprietary to suppliers. Whilst, the use of clay sol does offer some unique advantages over the use of clay powder in terms of the ease of handling of the sol thereby reducing inherent safety issues arising from inhalation of clay powder during processing, the use of clay sol produces alternative problems which need to be addressed to allow efficient processing. Such problems include the need for the use of a preservative as the clay is in liquid form as well as increased processing costs due to the high price of clay sol and the additional expense incurred to process a sol mixture into a detergent liquid.

In addition, a disadvantage of using clays as a main thickening agent in detergent compositions is that they are prone to interaction with other ingredients, with the result that the viscosity of the composition changes over time and syneresis may occur. Whilst formulations also exist using citrus fibre in combination with clay sol as the external structurants, such formulations have also been found to exhibit stability issues. In an attempt to reduce formulation costs and overcome the problems associated with known detergent formulations, the present inventors have now devised an improved, novel process which allows co-processing of structurants, specifically clay powder and citrus fibre, thereby overcoming inherent manufacturing problems and increased costs.

In addition, the present inventors have now devised a novel process whereby clay powder may be successfully co-processed with citrus pulp fibre to achieve an effective structurant system which overcomes the prior art problems previously experienced when using either structurant alone or in combination.

It is therefore an object of the present invention to provide an improved process for manufacturing co-structurant premixes for use in externally structured isotropic aqueous detergent liquids which overcome the problems associated with current processes.

It is a further object of the present invention to provide a detergent premix formulation comprising co-processed structurants and an externally structured isotropic aqueous detergent liquid which comprises same.

Summary of the invention

According to a first aspect of the present invention there is provided a process to manufacture an externally structured aqueous detergent liquid formulation comprising the steps of:

i) forming a premix of citrus fibre and water swellable clay powder; followed by ii) passing the premix of external structurants through a high pressure

homogeniser to form a structuring homogenised premix, followed by adding to the structuring homogenised premix;

iii) at least 2 weight % surfactant; and

iv) at least 0.001 weight % non-clay solid particles and milling to form the

externally aqueous structured detergent liquid formulation.

It is preferred that the premix of water swellable clay powder and citrus pulp fibre are passed through the high pressure homogeniser at a pressure of between 5 000 and 80 000 kPa. More preferably, the premix of water swellable clay powder and citrus pulp fibre are passed through the high pressure homogeniser at a pressure of between 7 00 and 70 000 kPa.

Such pressures are absolute pressures.

Passing the premix of citrus fibre and water swellable clay powder though the high pressure homogeniser leads to structural disruption and hydration of the citrus fibres and clay powder forming the structuring homogenised premix. The structuring homogenised premix is then dispersed with the surfactant and non-clay particles to form the externally aqueous structured detergent liquid formulation.

In the present invention the external structurants are therefore citrus pulp fibre and water swellable clay, preferably laponite clay, which have undergone a mechanical treatment and are therefore able to absorb at least 15 times their own dry weight of water. More preferably, the citrus pulp fibre and water swellable clay absorb at least 20 times their weight of water.

It is preferred that the premix preferably comprises clay powder in an amount of at least 0.04 weight % and activated citrus pulp fibre in an amount of at least 0.02 weight %. More preferably, the amount of citrus pulp fibre in the premix comprises 0.02 to 2.5 weight %. Most preferably the amount of citrus pulp fibre in the premix comprises 0.04 to 1 .5 weight %.

In addition, the amount of water swellable clay in the premix comprises 0.04 and 5.0 weight %. Most preferably the amount of citrus pulp in the premix comprises 0.06 to 3.0 weight %.

It is also preferred that yield stress range of the structuring homogenised premix is in the range of 10 and 200 Pa. More preferably, the yield stress range of the structuring homogenised premix is in the range of 15 and 140 Pa.

Also in relation to the process of the present invention the preparation of the detergent formulation requires the addition of a surfactant wherein the surfactant comprises between 2 % to 70 weight of the detergent formulation. More preferably the amount of surfactant in the detergent formulation comprises 3 to 50 weight %. The amount of anionic surfactant present as part of the total amount of surfactant comprises between 5 and 70 weight %, and the amount of amphoteric surfactant present as part of the total amount of surfactant comprises 1 to 20 weight %.

Furthermore, also in relation to the process of the present invention the detergent formulation comprises the addition of one or more non-clay particles which are selected from the group comprising:

visual cues, perfume encapsulates, care additives, and cleaning ingredients.

The amount of non-clay particles in the detergent formulation preferably comprises between 0.001 and 20 weight %. More preferably, the amount of non-clay particles in the detergent formulation comprises between 0.01 and 10%.

In addition, the process of manufacturing a detergent formulation according to the present invention involves the addition of one or more antifungal agents and/or antibacterial agents. A dye may also be added to the formulation of the present invention.

Citrus fibre is derived from citrus fruit and advantageously comprises the peel of lemons and/or limes. Citrus fibres are capable of absorbing and binding at least 15 times its own weight of water, preferably at least 20 times and even up to 30 times its own weight.

According to a second aspect of the present invention there is provided a structuring homogenised premix of water-swellable clay and citrus fibre pulp for use in an externally structured aqueous detergent liquid formulation comprising: at least 0.04 weight % water-swellable clay and at least 0.02 weight % citrus fibre.

More preferably the amount of citrus fibre pulp in the premix comprises 0.02 to 2.5 weight %. Most preferably the amount of citrus fibre pulp in the premix comprises 0.04 to 1 .5 weight %.

In addition, the amount of water swellable clay in the premix comprises 0.04 to 5.0 weight %. Most preferably the amount of water swellable clay in the premix comprises 0.06 to 3.0 weight %. Furthermore, the yield stress range of the premix comprises 10 and 200 Pa. More preferably, the yield stress range of the premix comprises 15 and 140 Pa. The premix pressure range is preferably 5 000 and 80 000 kPa. More preferably the premix pressure range is 7 000 and 70 000 kPa.

The inventors have found that the use of a premix of water-swellable clay and activated citrus pulp fibres offers a number of benefits when preparing detergent liquid formulations over using activated citrus fibres alone or water-swellable clay alone, or separately activated citrus fibres later combined with a water swellable clay.

Consequently according to a third aspect of the present invention there is provided an externally structured aqueous detergent liquid formulation obtainable using the process of any of claims 1 to 10 comprising: citrus fibre and water swellable clay powder in the form of a homogenised premix, wherein the composition comprises:

i) at least 0.04 weight % clay powder;

ii) at least 0.02 weight % citrus pulp fibre;

iii) at least 2 weight % surfactant; and

iv) at least 0.001 weight % non-clay solid particles. The externally structured aqueous detergent liquid composition according to the second aspect of the present invention preferably comprises an homogenised premix of water-swellable clay powder and citrus fibre comprising a yield stress of most preferably between 10 and 200 Pa. More preferably the homogenised premix of clay powder and citrus fibre pulp comprises a yield stress of 12 to 170 Pa. Most preferably the homogenised premix of clay powder and citrus fibre pulp comprise a yield stress of between 15 and 140 Pa.

The level of citrus fibre pulp in the formulation comprises 0.02 to 2.5 weight %. More preferably the level of citrus pulp in the formulation comprises 0.02 to 0.16.

The level of water swellable clay in the formulation comprises 0.04 to 0.5 weight %. More preferably the level of water swellable clay in the formulation comprises clay 0.04 to 0.45 weight %. The externally structured aqueous detergent liquid composition preferably further comprises one or more antifungal agents and/or antibacterial agents, and/or one or more dyes. In addition, the externally structured aqueous detergent liquid formulation preferably comprises citrus fibre in a range of 0.02 to 2.5 weight %. More preferably the externally structured aqueous detergent liquid formulation preferably comprises citrus fibre pulp in a range of 0.02 to 0.16 weight %. Furthermore, the clay powder is preferably present in the range of 0.04 to 0.5 weight %. More preferably, the clay powder is preferably present in the externally structured aqueous detergent liquid formulation in the range of 0.04 to 0.45 weight %.

The present invention therefore provides an improved process for manufacturing co- structurant premixes for use in externally structured isotropic aqueous detergent liquids; detergent premix formulations comprising co-processed structurants and an externally structured isotropic aqueous detergent liquid which comprises same, all of which overcome the problems associated with current processes. In addition, the present invention also provides the additional and unexpected benefit that whilst the yield stress of the premix prepared in accordance with the present invention is reduced with respect to premixes formed for example using clay sol and citrus pulp as structurant processed separately; the overall yield stress of the final formulation is increased. Consequently the detergent formulation is able to

successfully suspend solid particles, present in the formulation without loss of stability.

Detailed description of the invention

Detergent compositions

1. Activated Citrus fibre

Citrus fruits (mainly lemons and limes) may be de-juiced to leave an insoluble plant cell wall material with some internally contained sugars and pectin. The 'spongy microstructure', known as albedo, may be used to make acidic, powdered citrus fibre. The structure is dried, sieved and then washed to increase the fibre content. Dried materials are typically large (with 100's micron cell fragment, consisting of tightly bound/ bonded fibrils). After milling a powdered citrus fibre material is obtained. This procedure leaves much of the natural cell wall intact whilst sugars are removed. The resultant swellable citrus fibre materials are typically used as food additives and are often employed for example in low fat mayonnaise.

Microscopy shows that powdered citrus fibre is a heterogeneous mixture of particles with various sizes and shapes. The majority of the material consists of aggregated lumps of cell walls and cell wall debris. However, a number of tube-like structures with an open diameter of about 10 micron, often arranged in clusters, may be identified. These, so called, xylem vessels are water transport channels that are mainly located in the peel of citrus fruits. The xylem vessels consist of stacks of dead cells, joined together to form relatively long tubes, 200 to 300 micron long. The outsides of the tubes are reinforced by lignin, which is often laid down in rings or helices, preventing the tubes from collapse due to the capillary forces acting on the tube walls during water transport.

A preferred type of powdered citrus fibre for detergent compositions and used in accordance with the present invention is available from Herbafoods under the tradename, Herbacel™ AQ+ type N citrus fibre. This citrus fibre has a total (soluble and insoluble) fibre content of greater than 80% by weight and soluble fibre content of greater than 20% by weight. It is supplied as a fine dried powder with low colour and has a water binding capacity of about 20 kg water per kg of powder.

To obtain adequate structure, powdered citrus fibre is activated (hydrated and opened up structurally) via a high shear dispersion process in water with clay powder when forming the premix of the present invention. It is advantageous to include a

preservative into the premix as the dispersed activated citrus fibre is biodegradable.

It is desirable that the shear applied to the citrus fibre should not be so high as to lead to defibrillation. Consequently, if a high-pressure homogeniser is used, it is preferably operated between 5 000 and 100 000 kPa, more preferably, between 7 000 and 70 000 kPa. The more shear that is applied the less dense the resulting particles. Whilst the morphology is changed by the high shear, process aggregate size appears not to be changed. Instead, the fibres breakdown and then fill the water phase. The shearing process also loosens the outer parts of the fruit cell walls and these are able to form a matrix that structures the water outside of the volume of the original fibre.

Pulped citrus fibre is much less expensive to produce that bacterial cellulose.

2. Water-swellable Clay

Suitable water swellable clays used in laundry applications are hydrous aluminium phylosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations. Clays form flat hexagonal sheets similar to the micas. Clays are ultrafine-grained (normally considered to be less than 2 micrometres in size on standard particle size classifications).

Clays are commonly referred to as 1 :1 or 2:1 . Clays are fundamentally built of tetrahedral sheets and octahedral sheets. A 1 :1 clay consists of one tetrahedral sheet and one octahedral sheet, and examples include kaolinite and serpentine. A 2:1 clay consists of an octahedral sheet sandwiched between two tetrahedral sheets and examples are illite, smectite, and attapulgite. The Smectite group includes dioctahedral smectites such as montmorillonite and nontronite and trioctahedral smectites for example saponite. Also, bentonite, pyrophylite, hectorite, sauconite, talc, beidellite. Other 2:1 clay types include sepiolite or attapulgite, clays with long water channels internal to their structure. Phylosilicates include: Halloysite, Kaolinite, Illite, Montmorillonite, Vermiculite, Talc, Palygorskite, Pyrophylite. Montmorillonite is a smectite phylosilicate

(Na,Ca)o.33(AI,Mg)2(Si₄0io)(OH)2^«nH₂0. Montmorillonite is a very soft phylosilicate group of minerals that typically form in microscopic crystals to form a clay.

Montmorillonite, is a 2:1 clay, meaning that it has 2 tetrahedral sheets sandwiching a central octahedral sheet. The particles are plate-shaped with an average diameter of approximately one micrometre. Montmorillonite is the main constituent of bentonite - a volcanic ash weathering product. Hectorite is a natural smectite clay with high silica content. Natural hectorite is a rare soft, greasy, white clay mineral.

Suitable water-swellable clays include: smectites, kaolins, ilites, chlorites and attapulgites. Specific examples of such clays include bentonite, pyrophylite, hectorite, saponite, sauconite, nontronite, talc and beidellite as smectite type clays. The water- swellable clay is preferably a smectite-type clay.

Montmorillonite clays, even in the presence of stabilising agents are sensitive to ionic strength. They lose their liquid structuring efficiency at high electrolyte levels normally present in many detergent compositions. Clays tend to collapse onto themselves or flocculate under these conditions. If this collapse occurs during storage the liquid will lose its physical stability, suffer syneresis and /or settling of solids. The preferred water-swellable clay used in accordance with the present invention is a smectite-type clay, selected from the group consisting of Laponites, aluminium silicate, bentonite and fumed silica. Most preferred commercial synthetic hectorites are the Laponites from BYK Additives (a legal entity of Altana). Particularly preferred synthetic hectorites are: Laponite S, Laponite ES, Laponite RD, Laponite RDS, Laponite XLS, Laponite ESL and Laponite EL. Laponite RD, XLG, D, EL, OG, and LV: are all lithium magnesium sodium silicates. Most preferred are Laponite EL, Laponite ESL and Laponite ES.

Other synthetic hectorite type clays include: Velum Pro and Velum F from RT

Vanderbilt and the Barasymacaloids and Proaloids from Baroid division of National Lead Company.

Synthetic smectites are synthesised from a combination of metallic salts such as salts of sodium, magnesium and lithium with silicates, especially sodium silicates, at controlled ratios and temperature. This produces an amorphous precipitate which is then partially crystallised. The resultant product is then filtered washed dried and milled to give a powder containing platelets which have an average platelet size of less than 100 nm. Platelet size refers to the longest lineal dimension of a given platelet. Synthetic clay avoids the use of impurities found in natural clay.

Laponite is synthesised by combining salts of sodium magnesium and lithium with sodium silicate at carefully controlled rates and temperatures. This produces an amorphous precipitate which is then partially crystallised by a high temperature treatment. The resulting product is filtered, washed, dried and milled to a fine white powder. The size of the clay is important. Thus the very fine synthetic hectorites are especially preferred because of their small particle size. Particle size is the size of a discreet grain of moistened clay. A suitable particle size is 0.001 to 1 micron, more preferably 0.005 to 0.5 micron and most preferably from 0.01 to 0.1 micron. The clay may be ground or crushed to bring the average size within the desired range.

Laponite has an average platelet size maximum dimension less than 100 nm. Laponite has a layer structure, which in dispersion in water, is in the form of disc-shaped crystals each being about 1 nm thickness and about 25 nm diameter. Small platelet size provides good sprayability, rheology and clarity. Preferably the clay has a particle size range in the colloidal range. Typically such clays provide a clear solution when they are hydrated, possibly because the clay particles do not scatter light when the clay is hydrated and exfoliates. Other larger clays will provide low shear viscosity build as required but the compositions will lack clarity.

Most preferred as the water swellable clay for use in the process and detergent formulations of the present invention is the synthetic clay supplied under the name Laponite EL, ES or ESL from BYK Additives as these combines a very small grain size with a tolerance to high ionic strength as found in detergent liquids. Laponite EL, ES or ESL form a dispersion in water and has a high surface charge. This is said to give it improved tolerance to electrolyte (including anionic surfactant). Laponite EL, ES or ESL are available in both powder and sol forms. Either is suitable for use in the detergent liquid compositions. Laponite has a layer structure which, in dispersion in water, is in the form of discshaped crystals. It can be envisaged as a two dimensional "inorganic polymer" where the empirical formula forms a unit cell in the crystal having six octahedral magnesium ions sandwiched between two layers of four tetrahedral silicon atoms. These groups are balanced by twenty oxygen atoms and four hydroxyl groups. The height of the unit cell represents the thickness of the Laponite crystal. The unit cell is repeated many times in two directions, resulting in the disc shaped appearance of the crystal. It has been estimated that a typical Laponite crystal contains up to 2000 of these unit cells. Macromolecules of this particle size are known as colloids. Natural clay mineral thickeners such as bentonite and hectorite have a similar disc shaped crystal structure but are more than one order of magnitude larger in size. The primary particle size of Laponite is much smaller than either natural hectorite or bentonite. The idealised structure would have a neutral charge with six divalent magnesium ions in the octahedral layer, giving a positive charge of twelve. In practice, however, some magnesium ions are substituted by lithium ions (monovalent) and some positions are empty. The clay has a negative charge of 0.7 per unit cell, which becomes neutralised during manufacture as sodium ions are adsorbed onto the surfaces of the crystals. The crystals become arranged into stacks which are held together electrostatically by sharing of sodium ions in the interlayer region between adjacent crystals. At 25°C in tap water and with rapid agitation, this process is substantially complete after 10 minutes. High shear mixing, elevated temperature or chemical dispersants are not required. A dilute dispersion of Laponite in deionised water may remain a low viscosity dispersion of non-interacting crystals for long periods of time. The crystal surface has a negative charge of 50 to 55 mmol.100^9"1. The edges of the crystal have small localised positive charges generated by absorption of ions where the crystal structure terminates. This positive charge is typically 4 to 5 mmol.100^9"1. The addition of polar compounds in solution (e.g. simple salts, surfactants, coalescing solvents, soluble impurities and additives in pigments, fillers or binders etc.) to the dispersion of Laponite will reduce the osmotic pressure holding the sodium ions away from the particle surface. This causes the electrical double layer to contract and allows the weaker positive charge on the edge of the crystals to interact with the negative surfaces of adjacent crystals.

The process may continue to give a "house of cards" structure which, in a simple system of Laponite, water and salt, is seen as a highly thixotropic gel. This gel consists of a single flocculated particle held together by weak electrostatic forces.

The water swellable laponite clay used to form the premix in the process of the present invention is in powder form and may be used in an amount of at least 0.04 weight %.

Preferably the water swellable laponite clay may be used in an amount of at least 0.05 weight %. More preferably the water swellable laponite clay may be used in an amount of at least 0.06 weight %.

In addition, the water swellable clay is preferably present in an amount of no more than 3.5 weight %. More preferably the water swellable clay is present in an amount of no more than 3 weight%. Most preferably the water swellable clay is present in an amount of no more than 2.5 weight%. Laponite EL, ES and ESL clay is also a preferred structurant for use with citrus pulp containing formulations as in the present invention as the clay allows access to lower citrus pulp formulations by using the clay as a co-structurant.

In accordance with the present invention, an activated citrus fibre and clay structuring premix may be prepared by milling using a high shear mixer, such as a Silverson. In the process of the present invention, the premix may be passed through several sequential high-shear stages in order to ensure full hydration and dispersal of the citrus fibre and clay to form an activated citrus fibre/clay powder dispersion.

Whilst the premix may be left to hydrate further (or age) following high shear dispersal, it is preferred that the activated premix is used whilst fresh. Furthermore, high pressure homogenised premixes are preferred over milled premixes, as the former are more weight effective to provide sufficient suspending duty to liquids.

It has been found that increasing the homogenisation pressure provides further increased weight efficacy to the premix. A suitable operational pressure is in the region of 5 000 to 80 000 kPa. More preferably, an operating pressure in the region of 10 000 to 50 000 kPa may be used.

As there is sometimes a lack of stability in detergent formulation prepared on a large plant scale due to entrapment of air within the formulation, which is often worsened by the micronization of air during milling, a mechanical de-aerator may also be used to remove the air suspended and trapped by the milling process from the structured liquids.

The use of co-streamed water swellable laponite clay and citrus pulp fibre in

accordance with the present invention serves to reduce the amount of aeration in the formulation, thereby reducing the amount mechanical de-aeration, leading faster operating times and reduced production costs.

The level of activated citrus fibre in a premix prepared in accordance with the present invention preferably lies in the range of 0.2 to 3 weight %. More preferably the level of activated citrus fibre in a premix prepared in accordance with the present invention preferably lies in the range of 0.1 to 2 weight %. Most preferably the level of activated citrus fibre in a premix prepared in accordance with the present invention preferably lies in the range of 0.04 to 1.5 weight %.

It will however be apparent to a skilled reader that the concentration of activated citrus fibre in the pre-mix depends on the ability of the equipment to deal with the higher viscosity especially at higher concentrations.

Preferably the amount of water in the premix is at least 20 times greater than the amount of citrus fibres. More preferably the amount of water in the premix is at least at least 25 times the amount of citrus fibres. Even more preferably the amount of water in the premix is as much as 50 times the amount of citrus fibres. It is also advantageous that there is excess water in order to hydrate the activated citrus fibre fully. Preferred premixes have a measured yield stress of at least 15 Pa measured using an Anton Paar serrated cup and bob geometry at 25°C.

When added to a liquid detergent composition activated citrus fibre boosts the yield stress and the pour viscosity of the composition at 21 ^s"1 and the composition is referred to as a shear thinning liquid. Yield stress and viscosity at 21^s"1 increase generally in line with the level of activated citrus fibre.

Activated citrus fibre has the further advantage that it is compatible with enzymes used in laundry and household care detergent compositions.

The water swellable clay/citrus pulp premix prepared in accordance with the present invention may be added to a detergent liquid formulation as a post dosed ingredient. Alternatively, the detergent liquid formulation may be formed by starting with a water swellable clay/citrus pulp premix prepared in accordance with the present invention followed by the addition of other ingredients as required. Some high shear is required to disperse the premix in the detergent formulation fully but the duty is not as demanding as for the premix preparation.

Activated citrus fibre also benefits from air free processing as this improves the stability of the resulting liquid compositions, especially with regard to 'bottom clear layer' separation. That is, air, particularly air micronized in a mill will undergo ripening resulting in unwanted 'lift' or flotation of the fibre structurant within the formulation resulting in an uneven appearance of the detergent formulation . It is desirable to use the activated citrus fibre at a high enough level to ensure that the external structuring network does not settle under its own weight. If the network settles then any suspended solid particles settle with the network. To avoid air entrapment in the structuring network, the amount of activated citrus fibre is preferably reduced to close to a minimum value required to suspend solid particles such as for example, encapsulated fragrance or ground olive stones used in house-hold cleaning

compositions. It has also been found that the presence of the clay as a portion of the external structuring system also assists in reducing the level of the activated citrus fibre needed in a detergent composition.

An activated citrus fibre/clay structuring premix in accordance with the present invention may alternatively be prepared by milling using a high shear mixer, such as a Silverson. The premix of clay and citrus fibre may be passed through several high shear stages in order to ensure full hydration and dispersal of the citrus fibre and clay to from the activated citrus fibre dispersion. The premix may be left to hydrate further (also known as aging) after the high shear dispersal. It is preferred however, that the activated premix is used whilst fresh, especially as the premix is in liquid format, leading to an increased problem of microbial activity with time if the premix is not used within a few hours.

However, high pressure homogenised premixes are preferred over milled premixes, as the former are more weight effective and provide sufficient suspending duty to liquids. Furthermore, increasing the homogenisation pressure provides further increased weight efficiency to the premix. A suitable operational pressure is in the region of 50 000 kPa. 3. Water

The detergent compositions prepared in accordance with the present invention are aqueous and water forms the majority of the solvent in the composition. Hydrotropes such as propylene glycol and glycerol/glycerine may also be included as co-solvents to a lesser extent than the water solvent. Water is required in the composition in order to keep other components of the composition such as for example, surfactants, polymers, soluble builders, enzymes etc in solution. The water referred to in the composition includes both free water and any bound water. The amount of water in the composition is preferably at least 20 weight %. More preferably the amount of water in the composition is at least 30 weight %.

4. Mixed surfactant system

The use of activated citrus fibre and clay as external structurants, means that there are few limitations on the type or the amount of mixed surfactant system which may be employed in the detergent composition. However, synthetic surfactants preferably form a major part of the surfactant system. Mixtures of synthetic anionic and nonionic surfactants, or a wholly anionic mixed surfactant system or admixtures of anionic surfactants, nonionic surfactants and amphoteric or zwitterionic surfactants may all be used according to the choice of the formulator for the required cleaning duty and the required dose of the detergent composition.

In addition, the surfactants forming the mixed surfactant system may be chosen from the surfactants described in 'Surface Active Agents' Vol. 1 , by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958,

'McCutcheon's Emulsifiers and Detergents' published by Manufacturing Confectioners Company or in Tenside Taschenbuch', H. Stache, 2nd Edn., Carl Hauser Verlag, 1981.

The amount of surfactant in the composition may range from 3 to 75 weight %. More preferably the amount of surfactant in the composition may range from 4 to 60 weight %. Most preferably the amount of surfactant in the composition may range from 6 to 50 weight %. It will also be appreciated by the skilled addressee that the optimum surfactant concentration will largely depend on the product type and the intended mode of use.

The anionic surfactant may also further include soap (that is, a salt of fatty acid). A preferred soap employed in detergent formulations according to the present invention is made by neutralisation of hydrogenated coconut fatty acid, for example Prifac® 5908 (ex Croda). Mixtures of saturated and unsaturated fatty acids may also be used. Nonionic detergent surfactants are well-known in the art. A preferred nonionic surfactant is a C₁₂-C₁₈ ethoxylated alcohol, comprising 3 to 9 ethylene oxide units per molecule. More preferred are C₁₂-C₁₅ primary, linear ethoxylated alcohols with on average between 5 and 9 ethylene oxide groups. More preferably, linear ethoxylated alcohols with an average of 7 ethylene oxide groups are employed.

Examples of suitable synthetic anionic surfactants include: sodium lauryl sulphate, sodium lauryl ether sulphate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, ammonium lauryl ether sulphate, sodium cocoyl isethionate, sodium lauroyl isethionate, and sodium N-lauryl sarcosinate. Mostly preferably, the synthetic anionic surfactants comprise synthetic anionic surfactant linear alkylbenzene sulphonate (LAS) or another synthetic anionic surfactant sodium alcohol ethoxy-ether sulphate (SAES), most preferably comprising high levels of sodium C12 alcohol ethoxy-ether sulphate (SLES). It is preferred for the detergent composition according to the present invention to comprise LAS.

A preferred mixed surfactant system comprises synthetic anionic with nonionic detergent active materials and optionally amphoteric surfactant, including amine oxide. Another preferred mixed surfactant system comprises two different anionic surfactants, preferably linear alkyl benzene sulphonate and a sulphate, for example LAS and SLES.

Synthetic anionic surfactants may be present, for example, in amounts in the range from about 5% to about 70 weight % of the mixed surfactant system.

The detergent compositions may further comprise an amphoteric surfactant, wherein the amphoteric surfactant is present in a concentration of 1 to 20 weight %. Preferably the detergent compositions comprise an amphoteric surfactant present in a

concentration of 2 to 15 weight %. More preferably the detergent compositions comprise an amphoteric surfactant present in a concentration of 3 to 12 weight % of the mixed surfactant system. Typical examples of suitable amphoteric and zwitterionic surfactants include: alkyl betaines, alkylamido betaines, amine oxides,

aminopropionates, aminoglycinates, amphoteric imidazolinium compounds,

alkyldimethylbetaines or alkyldipolyethoxybetaines. 5. Suspended non-clay particles

The composition preferably comprises suspended non-clay particles. These particles are preferably solid; that is to say they are neither liquid nor gas. However, within the term solid we include particles with either rigid or deformable solid shells which may then contain fluids. For example the solid particles may be microcapsules such as perfume encapsulates, or care additives in encapsulated form. The particles may take the form of insoluble ingredients such as silicones, quaternary ammonium materials, insoluble polymers, insoluble optical brighteners and other known benefit agents as described, for example, in EP1328616. The amount of suspended particles may be from 0.001 to up to 10 or even 20 weight%. One type of solid particle to be suspended is a visual cue, for example the type of flat film cue described in EP131 19706. The cue may itself contain a segregated component of the detergent composition. Because the cue must be water-soluble, yet insoluble in the composition, it is conveniently made from a modified polyvinyl alcohol that is insoluble in the presence of the mixed surfactant system. In which case, the detergent composition preferably comprises at least 5 weight % anionic surfactant. The suspended non-clay particles may be any type. This includes perfume

encapsulates, care encapsulates and/ or visual cues or suspended cleaning ingredients, solid opacifiers such as mica or other suspended pearlescent materials and mixtures of these materials. The closer the match of the density of the suspended particles to that of the detergent liquid, and the thicker the detergent liquid before addition of the external structurants the greater the amount of particles that may be suspended in the detergent formulation. Typically, up to 5 weight % of suspended particles may be suspended stably using the mixed external structuring system;

however, amounts up to 20 weight % are possible. Suspension is achieved through providing a yield stress. The yield stress needs to be larger than the stress imposed on the network by the microcapsules or cues otherwise the network is disrupted and the particles may sink or float depending on whether or not they are denser than the base liquid. Perfume microcapsules are almost neutrally buoyant and small, so the required yield stress is low. Air bubbles are bigger and have the biggest density difference and so require a high yield stress (greater than 0.5 Pa, depending on bubble size). If the yield stress is not too high the air bubbles may escape by floating and disengaging from the surface.

Microcapsules preferably comprise a solid shell. Microcapsules carrying an anionic charge should be well dispersed to avoid agglomeration issues. Microcapsules with a cationic charge may also be used. The microcapsule may have a melamine formaldehyde shell, and may have deposition aids decorating the shell such as polysaccharide or xyloglucan. Other suitable shell material may be selected from (poly)urea, (poly)urethane, starch, and hydroxy propyl cellulose. However, it is preferred that the microcapsule comprises a melamine formaldehyde shell deposited on the outside with polysaccharides or xyloglucan.

The average particle diameter of the microcapsules lies in the range from 1 to 100 micrometer and at least 90 weight % of the microcapsules preferably has a diameter in this range. More preferably, 90 weight % of the microcapsules have a diameter in the range 2 to 50 micrometers, even more preferably 5 to 50 micrometers. Most preferred are microcapsules with diameters less than 30 micrometers.

It is advantageous to have a very narrow particle size distribution, for instance 90 weight % of microcapsules in the range 8 to 1 1 microns. Microcapsules in the range 2 to 5 microns cannot be dispersed so effectively due to the high surface area of the smaller particles.

Preferably the composition comprises at least 0.01 weight % of microcapsules, preferably with an anionic charge. Such microcapsules may deliver a variety of benefit agents by deposition onto substrates such as laundry fabric. To obtain maximum benefit the microcapsules should be well dispersed through the liquid detergent composition and the vast majority of the microcapsules must not be significantly agglomerated. Any microcapsules that become agglomerated during manufacture of the liquid remain so in the container and will thus be dispensed unevenly during use of the composition. This is highly undesirable. The contents of the microcapsules are normally liquid. For example, fragrances, oils, fabric softening additives and fabric care additives are possible contents. Preferred microcapsules are particles termed core-in- shell microcapsules. As used herein, the term core-in-shell microcapsules refers to encapsulates whereby a shell which is substantially or totally water-insoluble at 40°C surrounds a core which comprises or consists of a benefit agent (which is either liquid or dispersed in a liquid carrier).

Suitable microcapsules are those described in US-A-5 066 419 which have a friable coating, preferably an aminoplast polymer. Preferably, the coating is the reaction product of an amine selected from urea and melamine, or mixtures thereof, and an aldehyde selected from formaldehyde, acetaldehyde, glutaraldehyde or mixtures thereof. Preferably, the coating is from 1 to 30 weight % of the particles. Core-in-shell microcapsules of other kinds are also suitable for use in the present invention. Ways of making such other microcapsules of benefit agents such as perfume include precipitation and deposition of polymers at the interface such as in coacervates, as disclosed in GB-A-751 600, US-A-3 341 466 and EP-A-385 534, as well as other polymerisation routes such as interfacial condensation, as described in US-A-3 577 515, US-A-2003/0125222, US-A-6 020 066 and WO-A-03/101606.

Microcapsules having polyurea walls are disclosed in US-A-6 797 670 and US-A-6 586 107. Other patent applications specifically relating to use of melamine-formaldehyde core-in-shell microcapsules in aqueous liquids are WO-A-98/28396, WO02/074430, EP-A-1 244 768, US-A-2004/0071746 and US-A-2004/0142868.

Perfume encapsulates are a preferred type of microcapsule suitable for use in the present invention.

A preferred class of core-in-shell perfume microcapsule comprises those disclosed in WO 2006/066654 A1. These comprise a core having from about 5% to about 50 weight % of perfume dispersed in from about 95 % to about 50 weight % of a carrier material. This carrier material preferably is a non-polymeric solid fatty alcohol or fatty ester carrier material, or mixtures thereof. Preferably, the esters or alcohols have a molecular weight of from about 100 to about 500 and a melting point from about 37°C to about 80°C, and are substantially water-insoluble. The core comprising the perfume and the carrier material are coated in a substantially water-insoluble coating on their outer surfaces. Similar microcapsules are disclosed in US 5,154,842 and these are also suitable. The microcapsules may attach to suitable substrates, for example, to provide persistent fragrance that is desirably released after the cleaning process is complete. 6. Liquid detergent compositions

The detergent compositions have sufficient yield stress, also called critical stress, of at least 0.08 Pa. Preferably the detergent compositions have a yield stress of at least 0.09 Pa. More preferably the detergent compositions have a yield stress of at least 0.1 Pa, and even at least 0.15 Pa measured at 25°C. These increasing levels of yield stress are capable of suspending particles of increasingly different density from the bulk liquid. A yield stress of 0.09 Pa has been found sufficient to suspend most types of perfume encapsulates. Pure clay is unstable and cannot provide effective structuring of an aqueous isotropic detergent liquid composition. The mixed external structuring system also stays dispersed; neither floating (to give bottom clear layer separation) nor sinking (to give top clear layer separation). This self suspension is achieved by ensuring that the structuring system wants to occupy all the volume of the detergent liquid. This is a function of the amounts of clay and activated citrus fibre used. To obtain this from activated citrus fibre alone has been found to generate a yield stress so high that air bubbles are suspended and these then destabilise the structuring network. The detergent liquid may be formulated as a concentrated detergent liquid for direct application to a substrate, or for application to a substrate following dilution, such as dilution before or during use of the liquid composition by the consumer or in washing apparatus. Cleaning may be carried out by simply leaving the substrate in contact for a sufficient period of time with a liquid medium constituted by or prepared from the liquid cleaning composition. Preferably, however, the cleaning medium on or containing the substrate is agitated. Product Form

The liquid detergent compositions are preferably concentrated liquid cleaning compositions. The liquid compositions are also pourable liquids.

Throughout this specification, all stated viscosities are those measured at a shear rate of 21 s^"1 and at a temperature of 25°C unless stated to be otherwise. This shear rate is the shear rate that is usually exerted on the liquid when poured from a bottle. The liquid detergent compositions according to the invention are shear-thinning liquids.

Manufacturing process

At the higher levels of activated citrus fibre and water swellable clay required to suspend heavier particles the amount of water that may be removed from a base to make up the premix separately becomes too large so post dosing of a structuring premix is not a viable option. Instead structured detergent compositions may be prepared starting with the activated fibre/water swellable clay to which the other ingredients are added in their normal order of addition. In addition to enabling the incorporation of the higher level of activated fibre/clay into the detergent liquid this has the further advantage that dispersion of the activated fibre/clay by high shear continues during the addition of the later ingredients rather than as a post shearing step, thereby reducing the batch time. It has also been found that the best practice is to de-aerate the liquid composition before filling it into containers. However, the external structuring system allows for more process flexibility and this step is not essential.

Optional ingredients

Activated citrus fibre and water swellable clay has been found to be compatible with usual ingredients that may be found in detergent liquids. Among which there may be mentioned, by way of example: polymeric thickeners; enzymes, particularly: lipase, cellulase, protease, mannanase, amylase and pectate lyase; cleaning polymers, including ethoxylated polyethylene imines (EPEI) and polyester soil release polymers; chelating agents or sequestrants, including HEDP (1 -Hydroxyethylidene -1 ,1 ,- diphosphonic acid) which is available, for example, as Dequest® 2010 from

Thermphos; detergency builders; hydrotropes; neutralising and pH adjusting agents; optical brighteners; antioxidants and other preservatives, such as antimicrobial agents including Proxel®; other active ingredients, processing aids, dyes or pigments, carriers, fragrances, suds suppressors or suds boosters, chelating agents, clay soil removal/ anti-redeposition agents, fabric softeners, dye transfer inhibition agents, and transition metal catalyst in a composition substantially devoid of peroxygen species. These and further possible ingredients for inclusion in the present invention are further described in WO 2009/153184.

Packaging

The compositions may be packaged in any form of container. Typically a plastic bottle with a detachable closure/pouring spout. The bottle may be rigid or deformable. A deformable bottle allows the bottle to be squeezed to aid dispensing. If clear bottles are used they may be formed from PET. Polyethylene or clarified polypropylene may be used. Preferably the container is clear enough that the liquid, with any visual cues therein, is visible from the outside. The bottle may be provided with one or more labels, or with a shrink wrap sleeve which is desirably at least partially transparent, for example 50% of the area of the sleeve is transparent. The adhesive used for any transparent label should not adversely affect the transparency.

EXAMPLES

The invention will now be further described with reference to the following non-limiting examples and accompanying drawings in which:

Figure 1 a - is a schematic representation of a traditional formulation route for preparing externally structured isotopic aqueous detergent liquid.

Figure 1 b - is a schematic representation of a formulation route for preparing externally structured isotopic aqueous detergent liquid according to the present invention.

Figure 2a - is a microscope image of a sample of citrus pulp and water swellable laponite clay processed according to the process illustrated in Figure 1 a.

Figure 2b - is a microscope image of a sample of citrus pulp and clay processed according to the process of the present invention and illustrated in

Figures 3a - is a photographic images of an externally structured isotopic aqueous detergent liquid prepared according to the process of the present invention following equilibration of the aqueous detergent at room temperature for 24 hours.

Figure 3b - is a photographic images of an externally structured isotopic aqueous detergent liquid prepared according to the process of illustrated in Figure 1 a

demonstrating deterioration of the structure of the detergent liquid,

following equilibration at room temperature for 24 hours.

Abbreviations

The following abbreviated names used in these examples have the following meanings:

ACF is high pressure homogenizer (HPH) activated citrus fibre (2

weight % premix).

Water is Demineralised water.

Glycerol is hydrotrope.

MPG is Monopropylene Glycol (hydrotrope).

Neodol Nl is a nonionic surfactant ex Shell

NaOH is 50% sodium hydroxide base.

LAS acid is linear alkyl benzene sulphonic acid anionic surfactant.

ME A is Monoethanolamine base

TEA is Triethanolamine base not present.

Prifac 5908 is saturated fatty acid (soap) ex Croda SLES(3EO) is SLES 3EO anionic surfactant.

Dequest 2066 is Diethylenetriamine penta(methylene phosphonic acid (or

Heptasodium DTPMP) sequestrant ex Thermphos.

Dequest 2010 is HEDP (1 -Hydroxyethylidene -1 ,1 ,-diphosphonic acid)

sequestrant ex Thermphos

EPEI is ethoxylated polyethyleneimine PEI600EO20 Sokalan HP20 ex

BASF

HPH High pressure homogenizer.

Neolone MIT 950™ is antimicrobial preservative, is methylisothiazolin-3- one in water ex Dow chemical

Perfume encaps is encapsulated perfume, Oasis Cap Det B72 ex Givaudan. Polynesie is a fragrance oil

Preservative is Proxel GXL™ antimicrobial preservative, 20% solution of 1 ,2 benzisothiazolin-3-one in dipropylene glycol and water ex Arch

Chemicals.

Perfume is free oil perfume.

Laponite EL is water swellable synthetic hectorite clay ex BYK Additives. Laponite RD is water swellable synthetic hectorite clay ex BYK Additives. Micro is ISP white microbeads (visual cues).

Viscolam CK57 is a cross-linked thickening polymer ex Lamberti.

Tinopal 5BM-GX is a fluorescer.

Kleen is an encapsulated fragrance.

Xpect®1000L is pectate lyase ex Novozymes.

Protease is Relase Ultra 16L EX ex Novozymes.

L blend is a blend of 3 parts Stainzyme (amylase) to 1 part Mannaway

(mannanase) ex Novozymes.

Savinase is Ultra 16L - is an enzyme Ex Novozymes

Liquitint a dye Experimental General procedure 1 - Traditional Formulation method

A general formulation route as illustrated in Figure 1 a, for preparing externally structured isotopic aqueous detergent liquid is as follows.

Firstly, the process involves the preparation of a citrus powder/water premix (100) comprising citrus fibre powder (Herbacel AQ plus N Citrus Fibre (ex: Herbafoods)), for example 2 weight %, as the external structurant. The citrus pulp is added slowly to a mixture of demineralised water and a preservative such as for example, Proxel GXL™ and the reactants stirred using an agitator stirrer with overhead drive operated at 200 rpm for 15 minutes ensuring that clumping does not occur, and to allow the fibres to hydrate sufficiently prior to activation. The citrus pulp powder/water premix is then processed using a high pressure homogenizer (HPH) (200) to activate the citrus pulp fibres. That is, the solubilised citrus pulp powder is homogenized at around 50 000 kPa, at a flow rate of 1 1 kg/hour using an APV2000 laboratory high pressure homogenizer available from SPX.

Separately, a clay formulation (300) is prepared in which clay for example 0.1 weight % and encapsulates, are mixed together with demineralised water as required by stirring at 300 rpm for 15 minutes.

The stirring rate of the clay formulation is then reduced to 250 rpm before adding the activated citrus pulp premix (210). The citrus pulp and clay mixtures are then mixed together for 5 minutes.

The stirring rate of the reactants is then further reduced to 200 rpm and other components selected from for example, fluorescers, alkalis (neutralizers), surfactants and sequestrants are added and all of the components stirred for 15 minutes before passing the formulation to a mill operating at between 1 .2 and 3.8 kJ/Kg energy.

Finally, additional components such as preservatives, dyes, perfumes and enzymes are combined with the milled formulation and stirred for 15 minutes at 200 rpm to produce the final detergent liquid formulation (400). Procedure 2 - Co-streamed method according to the present invention

A formulation route for preparing an externally structured isotopic aqueous detergent liquid as illustrated in Figure 1 b in accordance with the present invention is as follows.

In contrast to the traditional route described above in procedure 1 , the process of the present invention involves the initial preparation of a premix comprising demineralised water (as required) and a preservative such as for example, Proxel GXL™ (0.02%) to which is added citrus fibre powder (0.66 weight %) (150) as well as clay powder (1.33 weight %) (160) and the reactants stirred at 200 rpm for 15 minutes.

The citrus pulp powder/clay premix is then processed using a high pressure

homogenizer (HPH) to activate the citrus pulp fibres (250). That is, the citrus pulp powder in combination with the clay powder is hydrated and subsequently

homogenized at 50 000 kPa pressure, at a flow rate of 1 1 kg/hour using an APV2000 laboratory high pressure homogenizer available from SPX.

The activated citrus pulp fibres and clay premix is then combined with for example encapsulates and batch water and the reactants stirred for 5 minutes at 250 rpm (350).

The stirring rate of the activated citrus pulp and clay formulation is then reduced to 200 rpm and other components selected from for example, fluorescers, alkalis

(neutralizers), surfactants and sequestrants are added and the mixture stirred for 15 minutes. The formulation is then further processed by passing through a mill, operating at a rate of between 1.2 and 3.8 kJ/Kg energy.

Finally, additional components such as preservatives, dyes, perfumes and enzymes are combined with the milled formulation and components stirred for 15 minutes at 200 rpm to produce the final detergent liquid formulation (450).

Preparation of Detergent Liquids A series of detergent liquids were prepared using the method according to the present invention outlined in procedure 2 above for different rations of citrus powder and clay, for comparison with detergent liquids prepared using the traditional formulation method outline in general procedure 1 above. As appropriate, sufficiently fresh activated citrus fibre/clay premix was added to a mixer to give the required level of activated citrus fibre in the finished composition prior to milling. The mill used comprises a dual blade impeller. Dispersion of the final detergent formulation is achieved using an in-line industrial high shear mixer, Silverson (L5T) at a specific energy input as required. The specific energy (kJ/Kg) is defined as the mixing conditions which imparts energy to give a consistent structure throughout the liquid. This energy may be attained by varying the mixing power and the resonance time within the mixer. A specific energy of between 1.2 and 3.8 kJ/Kg is defined as a reasonable operating window for consistent structurant dispersal.

Rheology Flow Curve Measurements

Rheology measurements were recorded for both the premix prepared by activation of the citrus pulp in combination with water swellable clay powder such as, laponite clay in accordance with the present invention and for a premix prepared using separately activated citrus pulp premix, as well as for the final detergent formulations prepared using the two premixes. Rheology flow curves were subsequently generated for the final detergent formulations using the following three step protocol:- The instrument used is a Paar Physica, MCR300 with automatic sample changer (ASC).

Geometry measurement performed with - CC27, profiled DIN concentric cylinder. The measurements were taken at 25°C.

Step 1 - Controlled stress steps from 0.01 to 400 Pa; 40 steps logarithmically spaced in stress with 40 seconds being spent at each point to measure the shear rate (and hence viscosity); Step 1 is terminated once a shear rate of 0.1 ^s"1 is reached. Step 2 - Controlled shear rate steps from 0.1 to 1200 ^s"1; 40 steps logarithmically spaced in shear rate with 6 seconds being spent at each point to determine the stress required to maintain the shear rate and hence the viscosity.

Step 3 - Controlled shear rate steps from 1200 to 0.1 ^s"1; 40 steps logarithmically spaced in shear rate with 6 seconds being spent at each point to determine the stress required to maintain the shear rate and hence the viscosity.

The results of the first two steps are then combined being careful to remove any overlap and to ensure that the required shear rates were achieved at the start of the step.

The yield stress in Pascals (Pa) is then taken to be the value of the stress at a shear rate of 0.1 .^s"1 , that is, the equivalent of the y-axis intercept in a Herschel-Buckley plot of shear stress versus shear rate. The yield stress was then taken as the point at which the data cut the viscosity = 10 Pa.s, and the pour viscosity recorded as the viscosity at 20 ^s' both at 25°C.

Table 1 below details the yield stress and viscosity values obtained for a citrus pulp and clay premix, prepared via the co-streaming process according to the present invention and outlined above in procedure 2, versus a premix comprising independently activated citrus pulp only, combined with clay in the general procedure outlined above.

The results show that the yield stress of the co-streamed citrus pulp and clay premix is more that 60% lower than that of the independently activated clay premix. In contrast however, the yield stress of the co-streamed citrus pulp and clay premix in the final product is higher than that of the independently activated clay premix. This has the effect that the final detergent formulations are more stable.

In addition, it can be seen that for the detergent liquid prepared using the co-streaming method of the present invention, the detergent liquid remained stable after a 12 week storage period in contrast to the detergent liquid prepared using the general method which failed a stability test after only 1 week when stored at room temperature.

Therefore it can be seen that the stability of the final detergent formulation is improved using the method of the present invention in which the detergent is prepared with a co- streamed citrus pulp and clay premix. _ilxampe.

Table 1 - Comparative data for clay and citrus fibre premixes prepared by standard procedure 1 and co-stream procedure 2.

Citrus

Premix fibres Clay

Yield (weiqht % (weiqht Yield Viscosit

Process Stress in % in Stress of v at Energy

LU type (Pa) formuln.) formuln.) product 21s-¹ (kJ/Ka) Stability

Costream Stable at

1 2 70.5 0.053 0.106 0.635 895 3.8 12 weeks

Standard Failed

2 1 124 0.05 0.1 - - 3.8 overnight

Costream Stable at

3 2 59.1 0.05 0.1 0.444 600 1.2 12 weeks

Standard Failed

4 1 1 10.4 0.05 0.1 - - 1.2 overnight

Costream Stable at

5 2 54.7 0.05 0.1 0.446 441 2.8 12 weeks

Standard Failed

6 1 124.6 0.05 0.1 - - 2.8 overnight

Stable at

4 weeks.

Costream Stability

7 2 84.8 0.15 0.1 1.028 786 1.2 ongoing

Standard Failed at

8 1 152.1 0.15 0.1 0.796 787 1.2 8 weeks

Stable at

4 weeks.

Costream Stability

9 2 84.7 0.15 0.1 0.824 512 1.2 ongoing

Standard Failed at

10 1 127.6 0.15 0.1 0.907 647 1.2 8 weeks

Costream Stable at

1 1 2 54.4 0.025 0.05 0.232 624 1.2 8 weeks

Costream Stable at

12 2 54.4 0.04 0.08 0.444 751 1.2 8 weeks

Costream Stable at

13 2 54.7 0.1 0.2 1 577 1.2 12 weeks

Costream Stable at

14 2 1 17.4 0.1 0.2 0.909 575 1.2 12 weeks

Stable at

4 weeks.

Standard Stability

15 1 155.4 0.1 0.2 0.763 556 1.2 ongoing

All processes had 2 % solids in premix except for example 14 which had 3% solids in premix.

In addition, examples using standard procedure 1 to compare with examples 1 1 and 12 failed at ratios of citrus pulp to water swellable clay of 0.05/0.1 .

Detergent Liquid Formulations. Detergent formulation prepared using citrus pulp/clav premix from example 1 in Table 1. Table 2

REAGENT AS 100% WEIGHT

ACTIVE

Demineralised water 59.172 2348.39

Non-clay particles 0.400 20.00

2% Citrus Pulp: 0.159 396.00

Laponite Clay Premix

Tinopal 5BM-GX 0.080 5.88

MPG 2.000 100.00

Glycerol 5.000 250.00

NaOH 1 .200 127.66

TEA 1 .690 85.35

Citric Acid 0.000 0.00

Neodol 25 7 13.720 686.00

LAS acid 9.150 471 .16

Prifac 5908

/ Palmera B1231 1 .500 75.00

SLES 3EO 4.570 326.43

Dequest 2066 0.340 53.13

0.02 5.00

Proxel™ GXL

Neolone MIT 950 0.00000 0.00

Perfume 1 .00000 50.00

Total 100% 5000.00

Table 3

Detergent formulation prepared using citrus pulp/clay premix from example 2 in Table 1 .

REAGENT AS 100% WEIGHT

ACTIVE

Demineralised water 59.172 2348.39

Non-clay particles 0.400 20.00

Laponite EL 0.106 264.00

2% Citrus Pulp

132.00

Premix 0.053

Tinopal 5BM-GX 0.080 5.88

MPG 2.000 100.00

Glycerol 5.000 250.00

NaOH 1 .200 127.66

TEA 1 .690 85.35

Citric Acid 0.000 0.00

Neodol 25 7 13.720 686.00

LAS acid 9.150 471 .16

Prifac 5908 1 .500 75.00

/ Palmera B1231

SLES 3EO 4.570 326.43

Dequest 2066 0.340 53.13

0.02 5.00

Proxel GXL

Neolone MIT 950 0.00000 0.00

Perfume 1 .00000 50.00

Total 100% 5000.00

Table 4

Detergent formulation prepared individuallv activated citrus pulp premix from example 3 in Table 1 .

REAGENT AS 100% WEIGHT

ACTIVE

Demineralised water 59.180 2369.39

Non-clay particles 0.400 20.00

2% Citrus Pulp: 0.15 375.00

Laponite Clay Premix

2% Citrus Pulp 0.050 125.00

Tinopal 5BM-GX 0.080 5.88

MPG 2.000 100.00

Glycerol 5.000 250.00

NaOH 1 .200 127.66

TEA 1 .690 85.35

Citric Acid 0.000 0.00

Neodol 25 7 13.720 686.00

LAS acid 9.150 471 .16

Prifac 5908 1 .500 75.00

/ Palmera B1231

SLES 3EO 4.570 326.43

Dequest 2066 0.340 53.13

0.02 5.00

Proxel GXL

Neolone MIT 950 0.00000 0.00

Perfume 1 .00000 50.00

Total 100% 5000.00

Table 5

Detergent formulation prepared individuallv activated citrus pulp premix from example 6 in Table 1 .

REAGENT AS 100% WEIGHT

ACTIVE

Demineralised water 58.390 2277.39

Non-clay particles 0.300 15.00

Laponite Clay 0.100 5.00

2% Citrus Pulp 0.050 125.00

Tinopal 5BM-GX 0.080 5.88

MPG 0.000 0.00

Glycerol 7.000 351 .76

NaOH 1 .550 164.89

TEA 1 .690 85.35

Citric Acid 0.620 62.00

Neodol 25 7 13.720 686.00

LAS acid 9.150 471 .16

Prifac 5908

75.00

/ Palmera B1231 1 .500

SLES 3EO 4.570 326.43

Dequest 2066 0.340 53.13

Proxel GXL 0.02000 5.00

Perfume 0.92 46.00

Total 100% 5000.00

Table 6

Detergent formulation prepared individuallv activated citrus pulp premix from example 13 in Table 1 .

REAGENT AS 100% WEIGHT

ACTIVE

Demineralised water 58.231 1897.39

Non-clay particles 0.300 15.00

2% Citrus Pulp:

750.00

Laponite Clay Premix 0.300

Tinopal 5BM-GX 0.080 5.88

MPG 0.000 0.00

Glycerol 7.000 351 .76

NaOH 1 .550 164.89

TEA 1 .690 85.35

Citric Acid 0.620 62.00

Neodol 25 7 13.720 686.00

LAS acid 9.150 471 .16

Prifac 5908

75.00

/ Palmera B1231 1 .500

SLES 3EO 4.570 326.43

Dequest 2066 0.340 53.13

Proxel GXL 0.02000 5.00

Neolone MIT 950 0.00950 5.00

Perfume 0.92000 46.00

Total 100% 5000.00

Table 7

Detergent formulation prepared individually activated citrus pulp premix from example 14 in Table 1 .

It may be seen that in Table 7 there is a more concentrated co-streamed premix of 3%. This concentration decreases the volume of water being processed into the premix without impacting upon stability.

Following preparation of the detergent liquids defined above using the premix prepared by the method of the present invention, detergent liquids stability tests were performed as follows. Aeration Test

The liquid detergent formulations were monitored for the appearance of air bubbles in the liquid formulations. The presence of air bubbles in the formulation may result in the break-down of the structure of the detergent formulation as a result of collapse of the citrus fibre. The presence of air bubbles in the detergent formulations was graded from AO to A3. A value of AO indicated zero or minimal air bubbles whilst a value of A2 to A3 indicated the presence of an extensive amount of air bubbles. As may be seen in Table 5 below, the detergent formulation prepared using the premix from example 1 had an aeration value of AO.

Photographic stability tests or 'dip' tests

'Dip test' - test for 'drop' or 'lift' visible inside detergent formulation

The liquid detergent formulations were also monitored for the appearance of a nonuniform region developing at the top or the bottom of the formulation. Photographs were taken of liquid detergent formulations in clear containers. The detergent liquid formulations were visually compared for formulations prepared using the co-streamed procedure of the present invention versus liquid detergent

formulations prepared using the non-co-streamed general procedure, as shown in Figures 3a and 3b respectively, following equilibration for 24 hours at room

temperature.

An example of a non-uniform region is discernible towards the top of the detergent liquid formulation illustrated in Figure 3b in which region Ά depicts a clear, non-uniform region which is indicative of a break-down in the uniformity of the detergent liquid and is different in appearance to the remainder of the detergent liquid. Region 'A' is referred to as a 'drop' or 'dip' within the formulation. A drop or dip of 1-2mm when the liquid formulation is held at room temperature or 5 °C is acceptable. A drop of greater than 5 mm when the liquid formulation is held at room temperature or 5 °C is deemed a product failure. In Figure 3b, the drop is greater than 5mm.

E_lxampe

Table 8

Summary of stability tests for the detergent liquid formulations prepared in Table 1 .

VISUAL VISUAL APPEARANCE APPEARANCE VISUAL

RATIO OF 12 WEEKS AFTER 12 WEEKS APPEARANCE

CITRUS AFTER STRORAGE AT AFTER 12

PULP TO STORAGE AT 5 ROOM WEEKS STORED RESULTS CLAY °C TEMPERATURE. AT 37°C

0.053 Stable at 12 /0.106 AO 2mm tcl AO 2mm tcl AO, 1 mm tcl weeks

0.05/0.1 >5mm tcl >5mm tcl > 5mm tcl Failed overnight

Stable at 12

AO < 1 mm tcl AO 2mm tcl AO, <1 mm tcl

0.05/0.1 weeks

0.05/0.1 >5mm tcl >5mm tcl >5mm tcl Failed overnight

Stable at 12

AO 1 mm tcl AO 1 mm tcl AO, <1 mm tcl

0.05/0.1 weeks

0.05/0.1 >5mm tcl >5mm tcl >5mm tcl Failed overnight

Stable at 4

AO 2mm tcl AO 1 mm tcl AO, 1 mm tcl weeks (stability

0.15/0.1 ongoing)

Failed at 8

0.15/0.1 AO >5mm tcl AO 1 mm tcl AO, 1 mm tcl weeks

Stable at 4

A1 2mm tcl A1 1 mm tcl AO, 1 mm tcl weeks(stability

0.15/0.1 ongoing)

Failed at 80 0.15/0.1 AO 4mm tcl AO >5mm tcl AO, >5mm tcl weeks

Stable at 8

AO < 1 mm tcl AO <1 mm tcl AO weeks (stability1 0.025/0.05 ongoing)

Stable at 8

AO 1 mm tcl AO 1 mm tcl AO weeks (stability2 0.04/0.08 ongoing)

Stable at 12

AO 1 mm tcl AO 4mm tcl AO, <1 mm tcl

3 0.1/0.2 weeks

Stable at 12

AO < 1 mm tcl AO 1 mm tcl AO, 2mm dip

4 0.1/0.2 weeks

In Table 9 stability tests are indicated for a detergent formulation prepared in

accordance with example 3 and formulated as indicated in Table 2 with a citrus pulp to clay ratio of 0.05/0.1 and stored over a range of conditions. TABLE 9

In contrast to the results shown in Table 9, Table 10 provides the stability tests for a detergent formulation prepared in accordance with example 2 and formulated as indicated in Table 4 with citrus fibre pulp activated in the absence of clay, at a ratio of 0.05 to 0.1 citrus pulp to clay and stored over a range of conditions. As can be seen in Table 10, all samples failed.

TABLE 10

Therefore it may be seen from the results above that for tests performed using liquid detergent compositions formulated with premixes prepared using the co-streaming procedure according to the present invention compared with standard premix methodology, for a range of structurant ratios, the liquid detergent products formulated using the co-streamed premix procedure were equally or more stable than the liquid detergent products formulated using the standard premix procedure.

This is also seen in Tables 9 and 10 above which for premixes ratios of citrus fibre to clay, the liquid detergent product samples prepared using the co-streamed premix procedure, were stable over a range of temperatures and for a number of weeks.

Furthermore, for a preferred detergent formulation prepared using a co-processed structurant premix comprising a ratio of 0.05% citrus fibres/0.1 % water swellable laponite EL, clay, the results of the tests performed on detergent formulations prepared using this premix formulation found that the liquid detergent was much more stable than its standard procedure counterpart. In addition, the structure of detergent formulation products prepared using the co-streamed premix according to the present invention are also observed to be more homogeneous than detergent formulation products made by the standard method.

Microscope Images

Microscope images were recorded for a premix sample prepared using the co- streaming procedure according to the present invention in which citrus pulp is activated in the presence of water swellable laponite clay, and for a premix sample in which the premix sample is prepared in accordance with the general procedure in which citrus pulp in activated in the absence of another structurants. The images produced for the two samples are illustrated as Figures 2a and 2b respectively.

The images were acquired using a BX51 Olympus microscope fitted with a Marzhauser motorised stage and fitted with a Zeiss HRc Axiocam camera controlled by Zeiss Axiovision software. For each detergent liquid, a sample was contained in a cavity slide which was sealed with a coverslip. The images were recorded in transmission DIC mode at x 10 magnification which gave images with a lateral resolution of 1.29 um and a field of view of 892 x 669 um.

It may be seen from Figures 2a and 2b that there was a reduced level of structurant material visible for the sample prepared by the method according to the present invention using the co-streaming procedure compared with the premix prepared using the general procedure, indicating that a significant change to the premix had taken place. Conclusion

From the experiments and results above it has been observed that the yield stress of the premix prepared according to the method of the present invention, which comprised the activation of the citrus pulp in combination with water swellable, laponite clay was lower than the method which involves preparing a premix which comprises only citrus pulp.

In addition, it was also observed that for the premix prepared using the co-streaming process of citrus pulp and water-swellable laponite clay in accordance with the present invention, the yield stress increased over time. This is in contrast to the citrus fibre only premix for which the yield stress was observed to decrease over time.

Whilst not wishing to be bound by any particular theory, the inventors believe that the increase in yield stress for the premix prepared in accordance with the present invention is due to the inclusion of the clay structurant within the citrus pulp fibres during activation of the citrus pulp, with the result that the co-streamed premix gradually forms a gel over time, thereby increasing the yield stress of the premix.

The increased yield stress of the co-streamed premix also provides a stabilising effect when the premix is used in final detergent liquid formulations as evidenced by the lack of air bubbles in the detergent, and the lack of 'dip' seen in the formulations once equilibrated (Figure 3a versus Figure 3b).

Consequently as a result of the increased stability observed for detergent formulations prepared using a premix in which the citrus pulp fibres are activated with the water swellable laponite clay in accordance with the present invention, it is possible to use lower levels of structurant combinations such as for example, citrus pulp/clay 0.05% /0.1 %. Lower levels of structurant combinations were previously not accessible and available to detergent formulators due to the instability of the structurant combinations. Therefore the present invention provides an improved process for producing stable co- structurant premixes wherein the structurants are processed together and at lower quantities when prepared singularly and which are able to be used in detergent formulations to provide products which are stable at all temperatures for 12 weeks thereby conforming to current industry standard testing.

Previously it had not been possible to produce a stable detergent formulation using a ratio of 0.05/0.1 citrus pulp fibre to water swellable clay. Therefore the process of co- streaming the citrus pulp fibres and the water-swellable laponite clay powder together according to the present invention in for example a 2% solids premix through a high pressure homogenizer produces a product which is stable at all temperatures for 12 weeks and therefore overcomes problems associated with prior art processes.

Claims

Claims

1. A process to manufacture an externally structured aqueous detergent liquid formulation comprising the steps of:

i) forming a premix of citrus fibre and water swellable clay powder; followed by ii) passing the premix of external structurants through a high pressure homogeniser to form a structuring homogenised premix, followed by adding to the structuring homogenised premix;

iii) at least 2 weight % surfactant; and

iv) at least 0.001 weight % non-clay solid particles and milling to form an externally structured detergent liquid formulation.

2. A process according to claim 1 wherein the premix of water swellable clay powder and citrus fibre are passed through the high pressure homogeniser at a pressure of between 5 000 and 80 000 kPa.

3. A process according to claim 1 wherein the premix of water swellable clay powder and citrus fibre are passed through the high pressure homogeniser at a pressure of between 7 000 and 70 000 kPa.

4. A process according to any of claims 1 to 3 wherein the premix comprises clay powder in an amount of at least 0.04 weight % and citrus fibre in an amount of at least 0.02 weight %.

5. A process according to any preceding claim wherein the premix comprises water swellable clay powder at a maximum value of 5 weight %.

6. A process according to any preceding claim wherein the premix comprises citrus fibre at a maximum value of 2.5 weight %.

7. A process according to any preceding claim wherein the at least 2 weight % surfactant comprises between 5 % to 70 weight % anionic surfactant, and between 1 and 20 weight % amphoteric surfactant.

8. A process according to any preceding claim wherein the

non-clay particles are selected from the group comprising:

visual cues, perfume encapsulates, care additives, and cleaning ingredients.

9. A process according to any of claims 1 to 8 wherein the structuring homogenised premix of citrus fibre and water swellable clay powder comprises a yield stress of between 10 and 200 Pa.

10. A process according to any of claims 1 to 8 wherein the structuring homogenised premix of citrus fibre pulp and water swellable clay powder comprises a yield stress of between 15 and 140 Pa.

1 1 . A structuring homogenised premix of water-swellable clay powder and citrus fibre pulp for use in an externally structured aqueous detergent liquid formulation comprising: at least 0.04 weight % water-swellable clay powder and at least 0.02 weight % citrus fibre.

12. An externally structured aqueous detergent liquid formulation obtainable using the process of any of claims 1 to 10 comprising: citrus fibre and water swellable clay powder in the form of a homogenised premix, wherein the formulation comprises:

i) at least 0.04 weight % clay powder;

ii) at least 0.02 weight % citrus pulp fibre;

iii) at least 2 weight % surfactant; and

iv) at least 0.001 weight % non-clay solid particles.

13. An externally structured aqueous detergent liquid composition according to claim 12 further comprising one or more antifungal agents and/or antibacterial agents, and/or one or more dyes.

14. An externally structured aqueous detergent liquid composition according to claim 12 wherein the citrus pulp fibre is present in a range of 0.02 to 2.5 weight %.

15. An externally structured aqueous detergent liquid composition according to claim 12 wherein the clay powder is present in a range of 0.04 to 0.45 weight %.