WO2002083999A1

WO2002083999A1 - Wool scouring process

Info

Publication number: WO2002083999A1
Application number: PCT/AU2002/000455
Authority: WO
Inventors: John M. Swan
Original assignee: Hallmark Dell Pty Ltd
Priority date: 2001-04-12
Filing date: 2002-04-10
Publication date: 2002-10-24
Also published as: AUPR439901A0; NZ528619A

Abstract

The present invention relates to the clearing of raw wool and other greasy and/or waxy textile materials, and in particular to a process for scouring wool utilising anionic, non-ionic detergents, amphoteric detergents, or blends thereof. The invention also relates to scouring wool in an acidic environment. Furthermore, the invention relates to recovering significant percentages of the wool wax and allows for re-use of substantial quantities of the water used in the scouring.

Description

WOOL SCOURING PROCESS

The present invention relates to the cleaning of raw wool and other greasy and/or waxy textile materials, and in particular to a process for scouring wool utilising anionic, non-ionic detergents, amphoteric detergents, or blends thereof.

The invention also relates to scouring wool in an acidic environment. Furthermore, the invention relates to recovering significant percentages of the wool wax and allows for re-use of substantial quantities of the water used in the scouring. Raw wool, after being removed from sheep, is called "greasy wool" or

"fleece wool" and it contains large amounts of dirt, vegetable matter, suint salts (salts of long chain carboxylic acids) and wool wax. These need to be removed to create clean wool that can then be further processed. The greasy wool contains:

Suint (long chain hydroxy di-carboxylic acids) 3 - 10%

Wool wax (or wool grease) 6 - 15%

Dirt (or mineral matter) 5 - 20%

Vegetable matter 5 - 15%

When greasy wool is cleaned by a scouring process, clean wool is produced containing:

Suint 0.1 - 0.3% Wool wax 0.3 - 0.8%

Dirt 0.1 - 0.5%

Vegetable matter 1 - 10%

Wool fleeces are traditionally opened in hoppers and drum openers and the wool staples are then scoured by passing them through a series of water baths of varying temperatures containing detergents. The scouring action of these various organic detergents removes grease and dirt, together with other contaminants which are also present in raw wool. Scouring is the first stage in wool processing. It is a aqueous chemical and mechanical cleaning process using detergents, typically either nonylphenol ethoxylates or fatty alcohol ethoxylates at a usage of around 10 kg per 1000 kg of greasy wool, concentrations of 0.03 to 0.06% v/v in the scour bowls, reasonably high temperatures (65°C), and agitation to clean the wool.

In summary, wool scouring consists of four successive treatments of the raw wool as it passes through the scour train: firstly a washing process at temperatures around 28 to 30°C, designed to remove some of the dirt and suint, secondly a scouring process at temperatures around 65°C to remove most of the wool wax and remaining dirt and suint and other contaminants, thirdly a rinsing process to separate the last of the scour liquors entrained in the wool fibres, and fourthly a drying process to yield the scoured product. Most wool scours operate at around 65°C in the scour bowls to take advantage of the fact that wool wax liquefies at about 40°C, with lower temperatures in the wash and rinse bowls. Scouring is normally done without adjustment of the pH of the bowls, and so, because of the variety of wool scoured, the pH in the scour bowls is usually between 6 and 8. Some scourers add small quantities of an alkali such as sodium carbonate to the scour bowls, resulting in a higher pH, e.g., in the range 8 to 9. Wool scourers often use a combination of bowls in the scouring process which are well documented in the literature. These are typically:

^■ One or two washing or suint bowls at 25 to 30°C

^■ Two or three scour bowls at 50 to 70° C ^■ Two or three rinse bowls at 25 to 50° C.

The cleaned wool is finally dried prior to further processing.

There are a number of disadvantages of the currently available scouring techniques.

Firstly, existing detergents used in wool scouring, typically nonylphenol ethoxylates are not readily biodegradable as defined by Australian Standard

AS4351. It is clearly desirable to use readily biodegradable detergents and whilst not currently mandatory in Australia, detergents not considered readily biodegradable have been voluntarily removed from retail detergent applications such as for clothes washing and dish washing. Similar environmental concerns exist worldwide. Whilst there are various detergents classed as readily biodegradable that have been used for wool scouring such as fatty alcohol ethoxylates and sodium alpha olefin sulphonates, they usually require a higher dose level than existing nonylphenol detergents and are usually more expensive. As a consequence, they are not used to any great extent for cost and performance reasons.

Secondly, existing scouring processes lead to damage to the wool due to the pH of the system. Mildly alkaline solutions can lead to protein degradation and subsequent yellowing of wool. Wool proteins are easily degraded if wool is heated in mildly alkaline solution. By contrast, the proteins of wool have maximum stability at pH 4.8, the isoelectric point of wool protein. The isoelectric point is the pH value at which the protein molecules have zero overall electric charge. Scouring above the isoelectric point of wool increases damage to the wool.

Furthermore, most commercial wool scours have difficulty in recovering more than about 50% of the total wax from the wool scour liquors, even with use of highly expensive centrifuges. For each tonne of wool scoured there is a potential to recover approximately 100 kg of wool wax. Less than half this amount is recovered in normal scouring operations and hence over 50 kg of wool wax per tonne of wool scoured is sent out as part of the effluent stream. The wax and other impurities remaining in the waste liquors constitute a major environmental cost when these liquors are discharged to waste. Also a significant financial concern is that the 50% of wool wax that is not recovered not only has a large disposal cost, but represents an economic loss with respect to its potential sale value. The recovered wool wax is sold by the scourer for further processing.

Thus for every 1000 kg of greasy wool scoured, approximately 50 kg of wool wax is either discharged to the sewer system at significant cost and environmental effect, or treated by a variety of expensive treatment systems. The biodegradation of wool wax is relatively slow, and chemical means to break the conventional waste-liquor emulsions can result in the co-precipitation of wax and dirt as an unattractive sludge. In addition, water costs are increasing around the world and some scourers attempt to recover re-usable water from the waste liquors. This can be achieved only at a significant cost. The more wax and dirt that can be removed via the centrifuges in a scour, the lower will be the costs of water recovery and re-use.

The cost of treating the effluent from the scouring process represents one of the major costs to a scourer operation, second only to the cost of labour. For every kilogram of clean wool produced, five to eleven litres of mains or clean water is used. Discharge rates to sewer, based on the Biological Oxygen Demand (BOD) and Suspended Solids (SS) levels of the effluent, will continue to increase through regional government legislation in an effort to encourage high users of water to adopt water-saving and recycling methods. The cost of purchasing mains water is also increasing as the true costs of supplying drinking water begins to be incorporated into its price. When treating the effluent to remove the factors producing the BOD and

SS levels, a solid waste stream is produced which must either be treated or disposed of. Practices currently deal with this solid waste by either transporting it to specific landfill sites (the solid waste is classified as a "prescribed waste" and therefore commands a premium tipping cost) or a lagoonal sewerage system is used to settle/biodegrade the solid particulate and organic material. Eventually the solid material must be removed from the lagoons or the system breaks down.

There are three effluent streams produced in conventional wool scouring processes: the wash effluent containing some of the suint salts and mineral matter; the heavily-contaminated hot scour effluent, containing the emulsion of wool wax, mineral matter, vegetable matter and suint (referred to as the strong flow because of its high BOD and SS levels); and the rinse effluent (often referred to as the weak flow).

Any method that improves the efficiency of using water within a scouring operation will improve its triple bottom line - the economic, environmental and social aspects. The present invention aims to:

^■ Obtain a higher wool wax recovery from the strong flow to obtain a high proportion of the total wool wax initially adsorbed to the greasy wool; 6

More specifically, the pH in the scouring process is modified in the scouring process, preferably either in the scour bowl or prior to centrifugation. It is preferred that the pH be modified to the range 3 to 7 and preferably to between 4 and 5 in the scour bowl. Alternatively, the pH can be lowered to between 1 and 7 and preferably between 4 to 5 prior to centrifugation. This enables the aqueous emulsion formed from the detergent and the wool wax to be broken more easily, with an increase in the recovery rate of the wool wax.

According to another embodiment of the invention, there is provided a method of cleaning textile materials comprising: (a) subjecting the textile material to a washing process in a washing solution comprising water, or water containing a suitable wetting and/or chelating agent at a temperature of between about 15°C to about 35°C;

(b) separating the textile material from the washing solution and subjecting the textile material to a scouring process in an aqueous scouring solution comprising long-chain organic sulphonic acid with optional adjustment of the pH of the scouring solution, such that the pH of the solution is in the range 3 to 7, and preferably 4 to 5;

(c) removing the textile material from the scouring solution, followed by rinsing and drying. Preferably the wetting and/or chelating agent is selected from citric acid, nonyl phenol ethoxylate, polyphosphoric acid, sodium alkyl sulphate, Calgon™, sodium tripolyphosphate and long chain sulphonic acids, which are most preferred. Preferably the method includes repeated washing, scouring and rinsing steps, preferably with counter-current flow of aqueous solution and textile material.

The preferred long chain organic sulphonic acid detergent used in the scouring process can be blended with other detergents if desired.

In a preferred embodiment of the invention effluent from the washing step(s) is used in fertiliser production as a source of sodium and potassium salts, in the case where the textile material is wool or the like.

Preferably the textile material to be cleaned is oily, waxy and/or greasy textile material including animal and/or synthetic and/or vegetable fibres or textiles woven from them. For example, animal fibres include sheep's wool, 5

^■ Allow recycling of the strong and weak flows, thereby reducing the cost of mains water purchased and reducing the volume of the discharge effluent;

■ Concentrate the solid waste stream, with possible diversion to a composting operation.

Another disadvantage of existing scouring systems is the entanglement of the wool during scouring. The entanglement increases with water temperature, pH and time of agitation.

SUMMARY OF THE INVENTION

It is thus proposed to provide a wool scouring system and method where one or more of the foregoing disadvantages of existing systems are minimised or removed:

In particular, a method for scouring wool is provided in which anionic detergents, non-ionic detergents, amphoteric detergents or blends of anionic, non-ionic and amphoteric detergents are used. Typically, the anionic detergents are alkylaryl sulphonic acids and their salts, alkyl sulphonic acids and their salts, alpha-olefin sulphonic acid and its salts, alcohol sulphates and their salts, alcohol ethoxy sulphates and their salts, alkyl sulphosuccinic derivatives, alkyl ether carboxylates, alkyl phosphates and alkyl ether phosphates, alkane sulphonates and their salts, alkyl phenol hydrogen sulphate and their salts, alpha-sulpho methyl esters, alkyl isethionates, and acyl sarcosinates, are preferred. The nonionic detergents are typically ethoxylated alkylphenol, ethoxylated alcohols, ethoxylated fatty acids, fatty acid alkanolamides, ethoxylated alkyl amines, alkyl amine oxides, alkyl amidoamine oxides, glyceryl fatty acid esters, sorbitan and ethoxylated sorbitan esters, sucrose esters, alkyl poly glucosides, ethylene oxide / propylene oxide copolymers, and ethoxylated/propoxylated alcohols. The amphoteric detergents are typically alkyl dimethyl betaines, alkyl amido betaines, alkyl sulphobetaines, alkyl amido sulphobetaines, imidazoline betaines, alkyl amino propionates, alkyl betaines, alkylamine oxides, and alkylamido propyl betaines.

The anionic, non-ionic, and amphoteric detergents can be used individually or in combination. cashmere, mohair and other goat hairs, down, alpaca hair, llama hair, camel hair, horse hair, cow tail hair, rabbit fur and insect fibres such as silk; vegetable fibres for example include cotton, corn silk and hemp fibre and synthetic fibres include nylon, Lycra™, polyester and the like. Preferably the textile material is sheep's wool.

Preferably the washing step is conducted at a temperature of between about 25°C to about 32°C, particularly preferably at about 28°C.

According to the nature and source of the wool to be cleaned, the aqueous washing solution can be either water alone or water containing an appropriate wetting and/or chelating agent such as an anionic detergent in low concentration, just sufficient to assist the "wetting-out" of the wool as it enters the wash bowl and/or a chelating (water softening) agent such as citric acid, polyphosphoric acid, sodium tripolyphosphate, Calgon™ and the like.

Preferably wax is extracted from effluent from the scouring step. For example, wax may be extracted from the effluent by centrifugation, leaving an aqueous acidic detergent solution which may be re-used. A chemical cracking process can be used to enhance wax recovery.

According to other embodiments of the invention there are provided textile material, washing and/or scouring step effluents and textile material wax produced according to the process outlined above.

The effluent liquor from the washing step will contain sodium and potassium suint salt, plus dirt and a small quantity of detergent or wetting agent, and this liquor has value in composting operations.

It has been found advantageous in the washing process to pass the wool through two successive baths, one containing water with some detergent or wetting agent (e.g., dodecylbenzene sulphonic acid) being added at the rate just sufficient to allow ready "wetting-out" of the wool. The second wash bowl can then contain water only, or water plus some inorganic acid, such as sulphuric acid sufficient to maintain the pH value of the first scour bowl at around 4 to 5 as a result of some of this acidic water moving with the wool via the squeeze rollers.

This process yields a large amount of liberated dirt and ensures that the bulk of the suint salts are eliminated before the wool is subjected to the scouring process. It has been found advantageous to remove as much dirt as possible in the washing process, as finely divided clays and other dirt can in general contribute to an increased stability of the subsequent emulsions of wool wax, leading to lower yields of recovered wax in the centrifugation step of a conventional wool scour. The preferred long-chain sulphonic acids for the claimed process are commercial linear-dodecylbenzene sulphonic acid which is in practice a mixture of the linear less than C-10, C-10, C-11 , C-12, C-13 , C-14 and greater than C-14 alkyl compounds, with a preponderance of the C-11 and C-12 acid. This commercial product , hereinafter referred to as linear alkylbenzene sulphonic acid is a preferred scouring agent, as are the individual sulphonic acids it contains. All these products usually contain a few percent of free sulphuric acid.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the cleaning of wool and other textile materials, and in particular to a process for scouring raw wool which involves the use of anionic detergents, particularly those based on long-chain sulphonic acids. In particular, the scouring agent consists of a mixture of the free acids together with the corresponding sodium, potassium or ammonium salts of the acids such that the pH value of the scour liquor lies in the range 3 to 7, preferably 4 to 5. The overall process also preferably involves the use of a strong acid such as sulphuric acid which is added to the grease-laden scour liquor just prior to centrifugation so as to lower the pH to a value between 1 and 7, preferably 4 to 5. The strong acid can also be added at other points in the process. This lowering of the pH essentially "cracks" the emulsion by virtue of the fact that anionic detergents are less effective in the free acid form as compared to their corresponding sodium, potassium or ammonium salts. In this way a high recovery of wool wax is achieved. The underflow from the final centrifuge can then be returned to the scour train. It can also be advantageous in some cases to add some sulphuric or other strong acid to the wash bowl or bowls, or the liquours discharged from these bowls, to assist in destruction of some of the suint salts present, and to promote settling of the dirt from the wash bowl effluent. As the wool passes from Bowl 1 to Bowl 2, it passes through squeeze rollers, with the expelled liquor being returned to Bowl 1. However, both here and at all successive squeeze rollers, the damp wool passing along the line carries with it about 40% of its own weight as liquor, held between the fibres by capillary forces.

Hence, according to the nature of the wool being cleaned, and the concentration and nature of the suint salts present, it may be necessary to add some strong acids to the scour bowls so that the pH of the scour liquors is held at around 4 to 7. Alternatively, for wools with a low suint content, or in a scouring system where the wool emerging from the wash bowl can be given a further water rinse to remove any adhering suint salts before it enters the main scour bowl, this scour bowl can be charged with a suitable mixture of free sulphonic acid and added alkali such that the pH value of the liquor is in the range 4 to 7.

Upon immersion in an aqueous solution above 40°C, the wool wax adhering to the wool fibres begins to melt forming an emulsion of wax, proteinacious material, dirt and suint. Wool scourers often use a combination of three hot scour bowls (containing a detergent) and two or three rinse bowls to remove the contaminants, leaving a cleaned wool. The residual vegetable matter is removed further along the early stage wool processing pipeline, mainly in the carding process. The hot scouring baths operate at approximately 50°C to 65°C to ensure that all the wool wax is molten. Modern detergents also show high efficiency in this temperature range. The rinse bowls, containing mains water, operate up to 50°C.

The liquor flow from one bowl to the next is in the opposite direction to the flow of wool - a counter-current system. The initial concentration of detergents in the scour bowls is relatively low, and more detergent is added on a semi- continuous or continuous basis as wool flows along the system, bringing with it more wax. When the wax content of the liquor in the first two scour bowls reaches a "saturation" level, where most of the detergent present has been used up in forming a stable emulsion of wool wax in water and cleaning efficiency is declining, the liquor can then be diverted on a semi-continuous or continuous basis to a hydrocyclone and centrifuge train. The hydrocyclones remove fine dirt and the centrifuges remove and concentrate wool wax.

In the present invention, wax recovery is greatly enhanced by the process of acidifying the liquor, at the point where it leaves the hydrocyclones and enters the primary centrifuge, with a strong acid such as sulphuric acid, so that the pH value is lowered to around 3. This "cracks" the emulsion, which is still at around 65°C, and the liquid wax is easily separated by centrifugation.

If the wool wax recovery in the hot wash effluent can be above the current 50%, the costs of either treating the effluent before discharge to sewer or direct discharge of this effluent to sewer are greatly reduced. Wool wax is a useful material in the pharmaceutical, cosmetic and other industries, and can be sold to intermediary agents to produce lanolin. World's current best-practice in the wool scouring industry allows approximately 45% to 50% of the wool wax from the strong flow to be recovered economically.

The acidic underflow from the centrifuge train can then be returned to the scour bowls. Other variants of this cracking process are outlined below.

Other efficiencies are also realised by the present invention, leading to further water savings and process streams which have a potential for waste minimisation, for example by use of these streams in compost manufacture.

With the higher yields of wax obtainable by utilisation of the present invention, the environmental and cost burden is greatly reduced. In addition, the sale of wool wax can contribute significantly to a profit margin for the wool scourer. With wools having a high suint content and very fine dirt, which is usually correlated with a high wax content, it is advantageous to first wash the wool at around 30°C in water containing only a small quantity of wetting agent, sufficient to assist wetting of the wool. This will allow the suint to function as an additional detergent to promote dirt removal. Acidification to destroy any residual suint can then be achieved, if required, in a second stage of the washing process, conducted prior to the scouring process.

The use of an acidic detergent such as linear alkylbenzenesulphonic acid provides opportunities for chemical "cracking" of the emulsion. As described above, the entire volume of the emulsion leaving the hydrocyclones can be acidified, thereby releasing most of the wax prior to the liquor entering the centrifuge train. In addition to the economic gain via the sale of the wax, this has significant implications for a simplified, lower-speed centrifuge system.

As a variant to acid cracking after the hydrocyclone stage, the liquor can first be first centrifuged in the normal manner in order to obtain un-oxidised wax.

Acid can then be added to the underflow to liberate the oxidised wax, which can be separately collected in a second centrifuge. At least two wax fractions can be encountered - the un-oxidised wax from the bulk of the fibre and oxidised wax from the fibre tips, which forms there as a result of photo-oxidation in sunlight throughout the growing season.

It can be noted that repeated passage of a wax emulsion through a series of centrifuges, with the associated pumping, contributes energy to the liquid so as to form a more and more finely divided emulsion, which increasingly resists centrifugal cracking. Chemical cracking of the emulsion helps to overcome this problem.

The choice of the best detergent for use in wool scouring depends on a number of factors including grease recovery rates, detergent efficiency, detergent cost, and suitability for use in the wool scouring process. In the past, wool scouring bowls were predominantly manufactured of mild steel. Only in the last 20 years or so has the use of stainless steel for bowl construction become the preferred material. The use of stainless steel bowls allows a wider choice of detergents than previously due to the better corrosion resistance of this material. Linear alkylbenzene sulphonic acid can be commercially produced using two different methods, to produce two quite different products with respect to corrosion properties.

The first method, a batch sulphonation, uses an excess of sulphuric acid to react with alkylbenzene to produce "Batch Acid" which contains about 10% sulphuric acid and about 90% alkylbenzene sulphonic acid.

The second method, a continuous sulphonation, uses sulphur trioxide gas to react with alkylbenzene to produce "Continuous Acid" that contains less than

2% sulphuric acid and about 95% alkylbenzene sulphonic acid.

In Australia, batch acid was commercially produced in the past but the market converted to the more modern process about 30 years ago and around the world the latter process is the method of choice. The mild steel nature of the earlier scour bowls restricted the choice of detergents that could be used as use of batch acid, with its high level of sulphuric acid, would have significant corrosion problems with the mild steel scour bowls.

Continuous acid, on the other hand, with its much lower sulphuric acid content, does not significantly attack stainless steel, and can in fact be stored in mild steel for reasonably long periods of time.

Also of importance is the cost of the detergent, particularly compared to the most widely used detergents in wool scouring , the nonyl phenol ethoxylates.

Alkylbenzene sulphonic acid is normally supplied to detergent manufacturers as the acid containing 95% alkylbenzene sulphonic acid. The sulphonic acid is then normally neutralised with caustic soda and/or other neutralising agents to form a ready-to-use detergent, e.g., a dishwashing liquid.

Neutralised alkylbenzene sulphonic acid can also be supplied as solutions in water up to about 25% active matter, or as a drum dried powder of about 80% active matter.

However, the cost of supplying these neutralised versions is considerably greater than supplying the acid, due to extra manufacturing steps and additional chemicals needed, and the extra freight of shipping lower active products.

Using the selling price of sulphonic acid as a base of 100, the following comparison can be made of the different detergents, as 100% active.

Sulphonic acid 100

Nonyl phenol ethoxylate 110

Sodium neutralised sulphonic acid (80%) 170 Sodium neutralised sulphonic acid (25%) 270

This indicates that use of the lower active neutralised versions of sulphonic acid are considerably more expensive than either sulphonic acid itself, or nonyl phenol ethoxylate. As it is normally the neutralised version that has been seen as the finished detergent, the much higher costs of these versions precluded their use in wool scouring unless the cleaning efficiency was much greater then expected. There are numerous measures of detergency and the results depend on the test method used, and the item to be cleaned, amongst other factors.

Compared to nonyl phenol ethoxylates, alkylbenzene sulphonic acids have poorer detergency on oily soil and poorer hard water tolerance but better performance on particulate soil. They are also not recognised for their emulsifying ability.

The scouring of wool involves the removal of wool wax (an oily soil) and a large quantity of dirt (a particulate soil) under conditions of often hard water to form an emulsion of the wool wax in water. It would normally be expected that alkylbenzene sulphonic acid under such conditions would be used at higher dosage rate than nonyl phenol ethoxylates. Our trials have shown quite the contrary.

The expensive neutralisation step is bypassed by in situ neutralisation of alkylbenzene sulphonic acid by greasy wool and its associated contaminants such as suint and dirt. This removes the cost hurdle, and also gives an unexpected efficiency in dosage rate of around 50% of the nonyl phenol ethoxylate.

EXAMPLES

LABORATORY TRIALS

Trial L1

Wool (500 g) containing 10.1% wax, was washed in water (8 L) at 30°C containing 0.2% linear alkylbenzene sulphonic acid. The dark brown liquor had a pH of 7. The wool was squeezed thoroughly but was not rinsed. The damp wool was divided into five equal portions. A wash liquor was prepared consisting of one litre of water containing 0.5% linear alkylbenzene sulphonic acid, the pH then being adjusted down to 5 by addition of sulphuric acid. The five portions of washed wool were then scoured successively in this liquor at 65°C, each lot being squeezed thoroughly, with the expressed liquor being returned to the scouring bowl. The final pH value of the scour liquor was 6.5. Sulphuric acid (80 ml of 5% solution) was added to bring the pH value to 2. This caused the separation of a voluminous precipitate of fine droplets of wool wax, which settled to the bottom of the vessel on account of entrainment of residual dirt (fine clay) particles.

The wax plus dirt was filtered off. After being dried, this material was then heated with mineral turpentine to dissolve the wax, and the mixture was filtered. The yield of wax was 41.5 g (i.e., 82% wax recovery).

This trial indicates the ability of emulsions of wool wax with alkylbenzene sulphonic acid to be de-stabilised by adjustment of the pH to give improved recovery rates of the wool wax.

Trial L2

This trial involved laboratory tests comparing sulphuric acid and polyphosphoric acid in relation to a washing process (dirt removal), followed by scouring (wax removal). The raw wool contained 10.12% grease. Equal portions (30 g) were used for each test. All washing tests were done at 26°C. After visual examination, the samples were then scoured at 65°C in 300 ml portions of 0.5% linear alkylbenzene sulphonic acid.

Sample 1 Water

Sample 2 0.05% linear alkylbenzene sulphonic acid Sample 3 0.05% linear alkylbenzene sulphonic acid (300 ml) plus 100 ml 0.25% sulphuric acid Sample 4 0.05% linear alkylbenzene sulphonic acid plus 10 ml 5% sulphuric acid Sample 5 0.05% linear alkylbenzene sulphonic acid plus 1 ml polyphosphoric acid

Sample 6 0.05% linear alkylbenzene sulphonic acid plus 2 ml polyphosphoric

The analytical results after scouring and drying were:

The dirt removal in washing for samples 5 and 6 was distinctly better than for samples 1 to 4, having a much whiter colour. Samples 1 to 4 were all reasonably similar by eye, with sample 1 being marginally the worst. The ash content of the scoured samples was also lowest for samples 5 and 6, where polyphosphoric acid was present in the wash liquor.

This shows that adjustment of pH by addition of polyphosphoric acid aids in the removal of dirt, and that scouring in acid conditions (samples 2 to 6) gives acceptable scouring performance.

Trial L3

To 200 ml of a 0.05% solution of sodium tripolyphosphate (STPP) at pH 9 was added 20 ml of 0.25% sulphuric acid, which reduced the pH value to 8.0. This solution was used to wash 15 g wool (wax content 13.82%) at 30°C. The pH of the liquor fell to 7.0 during this brief washing. Much dirt was released. The wool was then rinsed in water and scoured in 200 ml of 0.5% linear alkylbenzene sulphonic acid at 65°C for one minute, then rinsed. The residual grease content was 0.69%, ash 0.35%. This trial shows that the use of STPP in conjunction with linear alkylbenzene sulphonic acid gives improved dirt removal and very good grease removal. Trial L4

To a solution of Calgon™ (2.5 g) in water (500 ml) was added sodium tripolyphosphate (2.5 g) and the solution was then diluted to one litre. The final pH value was 8.0. Wool (15 g, wax content 13.82%) was then washed in a 200 ml portion of the Calgon/SPP solution. Much dirt was released. When this wash liquor was acidified to pH 3, the dirt settled rapidly and a clear, pale-yellow supernatant could be easily decanted.

The washed wool, now very white, was then scoured for one minute in a 200 ml portion of 0.5% linear alkylbenzene sulphonic acid at 65°C. Very little dirt settled from the scour liquor. After rinsing and drying the wool was shown ^"to contain 0.69% grease, 0.30% ash.

This trial shows that use of Calgon and STPP in addition to linear alkylbenzene sulphonic acid scoured wool to acceptable grease levels, and that modification to lower pH increased the separation of the dirt from the wash liquor.

Trial L5

This trial used 20 grams of greasy wool. The wool was treated in an ultrasonic bath at 30°C for five minutes to simulate the first washing bowl. The wool was dried and the grease content measured by solvent extraction. The wool was then washed in a 0.1 % active solution of detergent at 65°C with agitation for three minutes then removed from the liquor and squeezed to simulate the squeeze rollers normally present in commercial scours. The wool was then washed in water at 35°C for one minute to simulate the rinsing step usually used in commercial scours and squeezed to simulate the squeeze rollers normally present in commercial scours. The wool was then dried and the grease content measured by solvent extraction.

The relative grease removal in the table below is based on linear alkylbenzene sulphonic acid having a grease removal of 100. Higher numbers for other detergents mean less grease recovery, lower numbers mean greater grease recovery.

This trial showed that the grease removal varies according to the detergent used. Linear alkylbenzene sulphonic acid was more efficient than the nonyl phenol ethoxylates normally used in wool scouring and as linear alkylbenzene sulphonic acid is normally cheaper then nonyl phenol ethoxylates, it is more cost effective.

MANUAL MINI-SCOUR TRIALS AND LAB TRIALS

Table 1 shows the final grease (wax) and ash contents of the scoured wool using linear alkylbenzene sulphonic acid as the scouring detergent from six trials at a manual mini-scour with the following configuration. The wool portions were gently agitated by hand in each bowl, and passed from one bowl to the rtext through squeeze rollers. This was a batch-wise process - there was no counter- current flow of liquors. Initial detergent concentrations were 0.05% in the wash bowls and 0.5% in the scour bowls, higher than would be used in a commercial counter-current system. In Trials 1 to 4 the pH of the scour was reduced by the addition of alkylbenzene sulphonic acid alone, in Trials 5 and 6, additional sulphuric acid was used.

Bowl 1 Suint - 50 L 30°C

Bowl 2 Scour - 50 L 30°C

Bowl 3 Scour - 50 L 65°C

Bowl 4 Rinse - 50 L 65°C

Bowl 5 Rinse - 50 L 50°C

Table 1

These trials show that scouring in acid conditions by the addition of sulphuric acid gives similar scouring performance to scouring in acid conditions without addition of sulphuric acid, and both of the above give scouring performance similar to commercially accepted practice. FULL SCALE SCOUR TRIALS

Trial C1

BowM (B1 ) Wash - 1 ,600 L 30°C

Bowl 2 (B2) Scour - 1 ,200 L 65°C

Bowl 3 (B3) Scour - 1 ,200 L 65°C

Bowl 4 (B4) Rinse - 600 L 28°C

Bowl 5 (B5) Rinse - 600 L 25°C

This trial washed 921 kg of raw wool at a rate of 175 kg/hr over 5.3 hr.

Initial grease content was 10.12%, ash, 9.88%.

STPP and Calgon™ were added to Bowl 1 (4 kg each) and Bowl 2 (2.75 kg each) and Calgon, no additions of sulphuric acid were made.

The pH of B1 was 7.5 and rose to 9.2; B2, 7.0 to 9.1 ; B3, 2.3 to 8.3; B4, 2.1 to 8.2. The average grease content of the cleaned wool was 0.69%, the lowest value being 0.53 and the highest 1.09.

This trial did not use sulphuric acid to adjust the pH of the bowls, but rather the natural effect of adding alkylbenzene sulphonic acid. This trial shows that scouring in acid conditions with the addition of STPP and Calgon gave wool of commercially acceptable quality.

Trial C2

The configuration for the scour was

Bowl 1 Wash - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2,400 L 29°C

Wool feed rate - 1092 kg per hour Wool type - crutchings, bellies and fleece blend

Wool vegetable matter - 4.0%

Trial length - 3 hours

The raw wool was fed at a rate of 1092 kg/hr and used 30 kg per 1000 kg of a typical detergent, nonylphenol 8 mole ethoxylate, which produced scoured wool with a grease content of 1.34% which was commercially acceptable.

One of the preferred detergents, linear alkylbenzene sulphonic acid, was used at the rate of 60% of the nonyl phenol ethoxylate detergent dose, i.e., 18 kg/1000 kg of greasy wool, for three hours. The pH of the scouring bowls was not adjusted and remained at similar levels to those encountered with the nonyl phenol 8 mole ethoxylate.

This use of linear alkylbenzene sulphonic acid produced commercially acceptable wool and was of similar quality to that produced earlier in the trial using nonyl phenol 8 mole ethoxylate.

This trial showed the linear alkylbenzene sulphonic acid can be used at 60% of the dosage rate of nonyl phenol ethoxylate to produce commercially acceptable scoured wool.

Trial C3

The configuration for the scour was

Bowl 1 Wash - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C.

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2,400 L 29°C

Wool feed rate - 1185 kg per hour greasy

Wool type - Locks

Wool vegetable matter - 0.5% Trial length - 3 hours

The raw wool was fed at a rate of 1185 kg per hour kg/hr and 6.24 kg per 1000 kg of a typical detergent, nonylphenol 8 mole ethoxylate was used, which produced scoured wool with a grease content of 1.21 % which was commercially acceptable

The preferred detergent, linear alkylbenzene sulphonic acid, was then introduced at the rate of 88% of the typical detergent dose, i.e., 5.5 kg/1000 kg of greasy wool, for three hours, pH of the scouring bowls was not adjusted and remained at similar levels to those encountered with the typical detergent. Scoured wool was produced with a grease content of 1.21% which was commercially acceptable.

This trial showed the linear alkylbenzene sulphonic acid can be used at 88% of the dosage rate of nonyl phenol ethoxylate to produce commercially acceptable scoured wool.

Trial C4

The configuration for the scour was

Bowl 1 Suint - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C Bowl 6 Rinse - 2,400 L 29°C

Wool feed rate - see table

Wool type - see table

Wool vegetable matter - see table Trial length - 5 days The normal usage rate of nonyl phenol 8 mole ethoxylate was used as a reference rate to determine the relative efficiency of blends of linear alkylbenzene sulphonic acid and nonyl phenol 8 mole ethoxylate.

Blends of detergents (linear alkylbenzene sulphonic acid and nonylphenol 8 mole ethoxylate) were used during the five day trial to give the results in the following table.

This trial showed that blends of linear alkylbenzene sulphonic acid and nonyl phenol 8 mole ethoxylate performed more efficiently than pure nonyl phenol 8 mole ethoxylate.

NPE = nonyl phenol 8 mole ethoxylate LAS = linear alkylbenzene sulphonic acid

Trial C5

The configuration for the scour was

Bowl 1 Suint - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2.400L, 29°C

Wool type - merino lamb and fleece blend

Wool vegetable matter - 0.3%

Trial length - 1 day

Linear alkylbenzene sulphonic acid detergent was used during the trial.

On the second half of the trial the pH was adjusted just prior to the first centrifuge and the grease flows generated were measured as follows:

This trial shows that wool of acceptable quality can be produced from acid scouring and that there is an improvement of over 4% in grease recovery compared to the recovery rate without adjustment of the pH.

Trial C6

The configuration for the scour was

Bowl 1 Suint - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2,400 L 29°C

Wool type - merino lamb and fleece blend

Wool vegetable matter - 0.3%

Trial length - 1 day

Modification of pH was made by additions of sulphuric acid prior to the centrifuge train.

This trial showed that pH modification prior to the centrifuge train increased grease recovery by over 20% compared to the recovery without pH adjustment. Trial C7

The configuration for the scour was

Bowl 1 Suint - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2,400 L 29°C

Wool type - merino lamb and fleece blend

Wool vegetable matter - 0.3%

Trial length - 1 day

This trial showed that pH modification prior to the centrifuge train increased grease recovery by over 23% compared to the recovery without pH adjustment.

Trial C8

The configuration for the scour was

Bowl 1 Suint - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2.400L 29°C

Wool type - cross bred lamb

Trial length - 5 hours

Trial C7 showed improved grease recovery rates and this trial incorporated four centrifuges rather then the normal three to ensure that the extra grease generated by the new process would not be above the capacity of three centrifuges to separate. The trial used linear alkylbenzene sulphonic acid.

This trial showed that the recovery rate of the grease can be improved by increasing the number of centrifuges in the centrifuge train as, with the extra recovery rate by use of pH adjustment the grease available for recovery can exceed the capability of the centrifuges.

Trial C9

The configuration for the scour was

Bowl 1 Suint - 5,500 L 30°C

Bowl 2 Scour - 7,800 L 65°C

Bowl 3 Scour - 11 ,700 L 69°C

Bowl 4 Scour - 11 ,700 L 58°C

Bowl 5 Rinse - 5,400 L 28°C

Bowl 6 Rinse - 2,400 L 29°C Trial length - 6 days

This trial involved a full week of full scale scour operation, with acid scouring using nonyl phenol 8 mole ethoxylate and linear alkylbenzene sulphonic acid individually at different times, totalling approximately 20% of the week. The acid scouring process involved adjusted the pH just prior to the centrifuge train by the addition of sulphuric acid to 4 to 7. Grease recovery for the week was 5% higher than would normally expected for a week scouring similar wools using nonyl phenol ethoxylate and normal operating conditions. This trial showed that, assuming normal grease recovery rates for the time the scour was using nonyl phenol 8 mole ethoxylate in normal conditions, the recovery rate when the scour was using the acid scouring process was 25% higher than normal.

Throughout this specification it is to be understood that the word "comprise" and related words such as "comprises" and "comprising" are intended to convey an inclusive meaning. That is, unless the context indicates otherwise, these words convey the possible inclusion of other integers or steps or features that may not be specifically referred to.

In the context of the above explanation it will be understood that the processes of the present invention may include other steps not specifically recited, such as further washing, scouring, rinsing, centrifugation, separation, pH adjustment, temperature alteration or other steps. Similarly, the solutions adopted for the washing, scouring, rinsing, centrifugation and pH adjustment steps may include chemical species in addition to those specifically recited, and particularly including common acids and/or bases, chelating agents, wetting agents, detergents, textile material conditioning agents and the like, as long as their presence is compatible with the goals of the step or process concerned.

Unless the context suggests otherwise, reference within this specification to prior art is not to be taken as an admission or suggestion that such prior art constitutes common general knowledge in the field.

It is to be understood that the present invention encompasses modifications and/or alterations not specifically recited, that would be readily apparent to a person skilled in the art, based upon the disclosure provided herein.

Claims

1. A method of cleaning textile materials comprising the use of one or more anionic detergents.

2. A method according to claim 1 wherein the anionic detergents are selected from alkylaryl sulphonic acids and their salts, alkyl sulphonic acids and their salts, alpha-olefin sulphonic acid and its salts, alcohol sulphates and their salts, alcohol ethoxy sulphates and their salts, alkyl sulphosuccinic derivatives, alkyl ether carboxylates, alkyl phosphates and alkyl ether phosphates, alkane sulphonates and their salts, alkyl phenol hydrogen sulphate and their salts, alpha-sulpho methyl esters, alkyl isethionates, and acyl sarcosinates.

3. A method according to claim 1 or claim 2 wherein one or more non-ionic detergents are blended with the anionic detergent.

4. A method according to claim 3 wherein the non-ionic detergents are selected from detergents that exhibit decreased emulsion stability as the pH is lowered.

5. A method according to claim 3 or claim 4 wherein the non-ionic detergents are selected from ethoxylated alkylphenol, ethoxylated alcohols, ethoxylated fatty acids, fatty acid alkanolamides, ethoxylated alkyl amines, alkyl amine oxides, alkyl amidoamine oxides, glyceryl fatty acid esters, sorbitan and ethoxylated sorbitan esters, sucrose esters, alkyl poly glucosides, ethylene oxide / propylene oxide copolymers, and ethoxylated/propoxylated alcohols.

6. A method according to any one of claims 1 to 5 wherein one or more amphoteric detergents are also selected.

7. A method according to claim 6 wherein the amphoteric detergents are selected from alkyl dimethyl betaines, alkyl amido betaines, alkyl sulphobetaines, alkyl amido sulphobetaines, imidazoline betaines, alkyl amino propionates, alkyl betaines, alkylamine oxides, and alkylamido propyl betaines.

8. A method according to any one of claims 1 to 7 wherein the textile material is selected from animal and/or synthetic and/or vegetable fibres or textiles woven therefrom.

9. A method according to claim 8 wherein the textile material is wool.

10. A method according to any one of claims 1 to 9 wherein the anionic detergent is a long chain organic sulphonic acid.

11. A method according to claim 10 wherein the anionic detergent is alkylbenzene sulphonic acid.

12. A method according to any one of claim 1 to 11 wherein the pH of the scouring solution is in the range of about 3 to about 7.

13. A method according to claim 12 wherein the pH of the scouring solution is in the range of about 4 to about 5.

14. A method according to claim 12 or 13 wherein the pH of the scouring solution is altered by the addition of an acid.

15. A method according to claim 14 wherein the acid is sulphonic acid.

16. A method of cleaning textile materials which comprises:

(a) subjecting the textile material to a washing process in a washing solution comprising water and optionally a suitable wetting agent, at a temperature of between about 15°C to about 35°C; (b) separating the textile material from the washing solution and subjecting the textile material to a scouring process in an aqueous scouring solution comprising one or more anionic detergents, with adjustment of the pH of the scouring solution if necessary, such that the pH of the solution is in the range of 3 to 7; (c) removing the textile material from the scouring solution.

17. A method according to claim 16 wherein the wetting agent is selected from citric acid, nonyl phenol ethoxylate, polyphosphoric acid, sodium alkyl sulphate, Calgon™ and long chain sulphonic acids.

18. A method according to claim 16 or claim 17 wherein the anionic detergents are selected from alkylaryl sulphonic acids and their salts, alkyl sulphonic acids and their salts, alpha-olefin sulphonic acid and its salts, alcohol sulphates and their salts, alcohol ethoxy sulphates and their salts, alkyl sulphosuccinic derivatives, alkyl ether carboxylates, alkyl phosphates and alkyl ether phosphates, alkane sulphonates and their salts, alkyl phenol hydrogen sulphate and their salts, alpha-sulpho methyl esters, alkyl isethionates, and acyl sarcosinates.

19. A method according to any one of claims 16 to 18 wherein one or more non-ionic detergents are blended with the anionic detergent.

20. A method according to claim 19 wherein the non-ionic detergents are selected from ethoxylated alkylphenol, ethoxylated alcohols, ethoxylated fatty acids, fatty acid alkanolamides, ethoxylated alkyl amines, alkyl amine oxides, alkyl amidoamine oxides, glyceryl fatty acid esters, sorbitan and ethoxylated sorbitan esters, sucrose esters, alkyl poly glucosides, ethylene oxide / propylene oxide copolymers, and ethoxylated/propoxylated alcohols or other detergents that exhibit decreased emulsion stability as the pH is lowered.

21. A method according to any one of claims 16 to 20 wherein one or more amphoteric detergents are also used.

22. A method according to claim 21 wherein the amphoteric detergents are selected from alkyl dimethyl betaines, alkyl amido betaines, alkyl sulphobetaines, alkyl amido sulphobetaines, imidazoline betaines, alkyl amino propionates, alkyl betaines, alkylamine oxides, and alkylamido propyl betaines.

23. A method according to any one of claims 16 to 22 wherein the textile material is selected from animal and/or synthetic and/or vegetable fibres or textiles woven therefrom.

24. A method according to claim 23 wherein the textile material is wool.

25. A method according to any one of claims 16 to 24 wherein the anionic detergent is a long chain organic sulphonic acid.

26. A method according to claim 25 wherein the anionic detergent is alkylbenzene sulphonic acid.

27. A method according to any one of claims 16 to 26 wherein the pH of the scouring solution is in the range of about 4 to about 5.

28. A method according to any one of claims 16 to 27 wherein the pH of the scouring solution is altered by the addition of an acid.

29. A method according to claim 28 wherein the acid is sulphonic acid.

30. A method according to any one of claims 16 to 29 which further includes the step of recovering wax from the effluent of the scouring step.

31. A method according to claim 30 wherein the wax is recovered from the effluent by centrifugation.

32. A method according to claim 30 or claim 31 wherein acid is added to the effluent prior to centrifugation to increase wax recovery.

33. A method of cleaning textile materials which comprises:

(a) subjecting the textile material to a washing process in a washing solution comprising water and optionally a suitable wetting agent, at a temperature of between about 15°C to about 35°C; (b) separating the textile material from the washing solution and subjecting the textile material to a scouring process in an aqueous scouring solution comprising one or more detergents, with adjustment of the pH of the scouring solution if necessary, such that the pH of the solution is in the range of 3 to 7;

(c) removing the textile material from the scouring solution.

34. A method according to claim 33 wherein the wetting agent is selected from citric acid, nonyl phenol ethoxylate, polyphosphoric acid, sodium alkyl sulphate, Calgon™ and long chain sulphonic acids.

35. A method according to claim 33 or 34 wherein the detergents are selected from non-ionic detergents, namely ethoxylated alkylphenol, ethoxylated alcohols, ethoxylated fatty acids, fatty acid alkanolamides, ethoxylated alkyl amines, alkyl amine oxides, alkyl amidoamine oxides, glyceryl fatty acid esters, sorbitan and ethoxylated sorbitan esters, sucrose esters, alkyl poly glucosides, ethylene oxide / propylene oxide copolymers, and ethoxylated/propoxylated alcohols.

36. A method according to any one of claims 33 to 35 wherein one or more amphoteric detergents are also used.

37. A method according claim 36 wherein the amphoteric detergents are selected from alkyl dimethyl betaines, alkyl amido betaines, alkyl sulphobetaines, alkyl amido sulphobetaines, imidazoline betaines, alkyl amino propionates, alkyl betaines, alkylamine oxides, and alkylamido propyl betaines.

38. A method according to any one of claims 33 to 37 wherein the textile material is selected from animal and/or synthetic and/or vegetable fibres or textiles woven therefrom.

39. A method according to claim 38 wherein the textile material is wool.

40. A method according to any one of claims 33 to 39 wherein the pH of the scouring solution is in the range of about 4 to about 5.

41. A method according to any one of claims 33 to 40 wherein the pH of the scouring solution is altered by the addition of an acid.

42. A method according to claim 41 wherein the acid is sulphonic acid.

43. A method according to any one of claims 33 to 42 which further includes the step of recovering wax from the effluent of the scouring step.

44. A method according to claim 43 wherein the wax is recovered from the effluent by centrifugation.

45. A method according to claim 43 or claim 44 wherein acid is added to the effluent prior to centrifugation to increase wax recovery.

46. Textile materials cleaned by the method of any one of claims 1 to 45.