USE OF A FIBRE COMPRISING COMPOSITE FIBRES OF CELLULOSE AND CELLULOSE ACETATE AS

BLEACH ACTIVATOR

The present invention relates to fibres. More specifically, the present invention relates to fibres which can be used as a bleach activator.

There are two distinct types of fibres used in the manufacture of textiles, namely natural fibres, for example cellulose fibres, and synthetic fibres, for example polyester, nylon and cellulose acetate fibres.

Synthetic fibres offer many advantages over natural fibres, for example synthetic fibres may be strong and light weight, fast drying and/or resistant to wrinkles and creases. However, synthetic fibres may be considered to have an unacceptable feel and/or appearance for certain textile applications.

To address this issue, it is known to blend synthetic fibres with other synthetic or natural fibres. Common examples of fibre blends include polyester/cotton blends and polyester/viscose blends.

There have also been attempts made in the prior art to intimately combine synthetic and natural fibres to impart certain characteristics of one type of fibre to the other.

United States patent number 6,258,304 describes a process for the preparation of lyocell fibre or film by extruding a solution of cellulose in amine oxide through a spinneret or film die at elevated temperature via an air gap into an aqueous precipitation bath, thereby to form said fibre or film. Our international application number WO201 1/048420 describes a biodegradable fibre comprising composite filaments of cellulose and cellulose acetate, and a process for making such a fibre comprising providing a solution dope comprising a blend of cellulose and cellulose acetate in an ionic liquid or in N-methylmorpholine (NMMO), and spinning the blend into a protic solvent to generate fibres.

Bleaches are often used for the removal of stains from textiles manufactured from fibres.

Bleaches work by removing coloured stains, altering the stain chromophore such that it is no longer coloured, and/or solubilising the stain molecules which can then be removed by a wash liquor.

Commonly used bleaches are based on peroxides/peroxide precursors such as hydrogen peroxide, sodium perborate and sodium percarbonate.

Bleach activators work by reacting with the peroxide/peroxide precursor, to form peracetic acid, which is a more kinetically powerful bleaching agent than the peroxide.

Known bleach activators include Λ/,Λ/,Λ/',/V -tetraacetylethylenediamine (TAED), nonanoyl benzene sulfonic acid (sodium salt) (NOBS), A/-[4-(thethylammoniomethyl) benzoyl] butyrolactam chloride (TBBC), sodium lauroyloxybenzene sulfonate (LOBS), 4-decanoyloxybenzoic acid (DOBA), benzoyloxybenzene sulfonate (BOBS), benzoylcaprolactam (BCL), 4-morpholinocarbonitrile (MOR) and acetyl caprolactam

These known bleach activators are typically formulated into a detergent. The bleach activators are ideally stable and compatible with the other components in the detergent. However, this is often not the case.

For solid detergents, a common approach to overcoming incompatibility between the bleach activator and the other detergent components, for example the peroxide precursor, is to encapsulate each component within a binder system, which physically separates the components prior to solubilisation. Commonly used binders include fatty acids, for example C9 and C16 fatty acids. However, these fatty acids may cause the detergent to have an unpleasant odour, leading to a poor consumer experience. To address this problem, detergent manufacturers often add perfumes or other masking agents to the detergent. However, this increases the manufacturing cost of the detergent.

For liquid detergents, overcoming incompatibility between the bleach activator and the other detergent components, particularly the peroxide precursor, may involve anionic activators and cationic surfactant complexes being dissolved with a non-ionic surfactant micelle in the detergent. Again, this increases the manufacturing cost of the detergent.

The use of bleach activators has many advantages, for example it allows bleaching to occur at lower temperatures which improves energy efficiency, reduces the environmental impact of the bleaching process, and increases fabric longevity. In addition, the use of bleach activators enables low temperature sanitisation and a reduction in odour formation due to microbial activity. However, the use of bleach activators in detergents may significantly increase the manufacturing cost of the detergent.

The present invention seeks to address the problems associated with the prior art.

In accordance with the present invention there is provided the use of fibres comprising one or more composite filaments of cellulose and cellulose acetate, as a bleach activator.

In this context, the term 'bleach activator' is used to describe a material that is capable of reacting with a peroxide and/or a peroxide precursor, to form peracetic acid.

Reference herein to composite filaments of cellulose and cellulose acetate shall be understood to mean filaments spun from a dope comprising cellulose and cellulose acetate.

Composite filaments of cellulose and cellulose acetate spun from the dope may comprise: a continuous phase of cellulose containing dispersed phases of cellulose acetate; a continuous phase of cellulose acetate containing dispersed phases of cellulose; and/or a co-continuous phase of cellulose and cellulose acetate, for example. The inventors of the present invention have surprisingly found that fibres comprising one or more composite filaments of cellulose and cellulose acetate are capable of reacting with a peroxide and/or a peroxide precursor, to form peracetic acid i.e. the fibres can be used as a bleach activator.

Without wishing to be bound by any such theory, it is believed that a peroxide, for example hydrogen peroxide, undergoes a perhydrolysis reaction with the cellulose acetate in the fibre to produce the corresponding peracetic acid. This can occur under the alkaline conditions of a domestic wash, for example.

Peracetic acids are known to react readily with oxidisable compounds, thus, facilitating the bleaching process.

As a result of the above, textiles comprising the fibres of the present invention may not require detergents containing a bleach activator. There are numerous advantages to formulating detergents without bleach activators. For example, the following problems can be avoided: incompatibility between the bleach activator and the other detergent components such as the peroxide precursor; poor solubility and stability of the bleach activator in the detergent; and the toxicity and environmental impact of the bleach activator in waste streams.

The weight ratio of the cellulose to the cellulose acetate in the composite filaments may be from 99.9:0.1 to 0.1 :99.9, from 99:1 to 1 :99, from 95:5 to 5:95, from 90:10 to 10:90, from 80:20 to 20:80, from 70:30 to 30:70, or from 60:40 to 40:60. The weight ratio of the cellulose to the cellulose acetate in the composite filaments may be from 99.9:0.1 to 50:50, from 90:10 to 50:50, from 80:20 to 50:50, from 70:30 to 50:50, or from 60:40 to 50:50.

The fibres may be coloured.

The colour may be effected by a disperse dye.

The disperse dye may be any known suitable disperse dye. For example, the disperse dye may be selected from: anthraquinone dyes, for example Colour Index Disperse Red 15, Colour Index Disperse Red 60, Colour Index Disperse Violet 4 and Colour Index Disperse Violet 26; azo dyes, for example Colour Index Disperse Yellow 3, Colour Index Disperse Orange 25, Colour Index Disperse Red 167, Colour Index Disperse Violet 33 and Colour Index Disperse Blue 79; nitroarylamine; coumarin; methine; naphthostyryl; formazan; and benzodifuranone.

Also provided in accordance with the present invention is a bleach activator comprising a fibre blend comprising fibres comprising one or more composite filaments of cellulose and cellulose acetate, and synthetic fibres.

Also provided in accordance with the present invention is the use of a fibre blend comprising fibres comprising one or more composite filaments of cellulose and cellulose acetate, and synthetic fibres, as a bleach activator.

The synthetic fibres may be any known suitable synthetic fibres, for example polyester fibres, nylon fibres, acrylic fibres, elastane fibres, cellulose acetate fibres, cellulose triacetate fibres, polylactic acid fibres, polypropylene fibres, or polyphenylene sulfide fibres.

The fibre blend may be coloured.

The colour may be effected by a disperse dye.

The disperse dye may be any known suitable disperse dye. For example, the disperse dye may be selected from those previously outlined.

Also provided in accordance with the present invention is a textile manufactured from the fibres comprising one or more composite filaments of cellulose and cellulose acetate as hereinbefore described.

Also provided in accordance with the present invention is a textile manufactured from the fibre blend as hereinbefore described.

Also provided in accordance with the present invention is a textile manufactured from the bleach activator as hereinbefore described.

Also provided in accordance with the present invention is a textile manufactured from the fibres comprising composite filaments of cellulose and cellulose acetate, and synthetic and/or natural fibres, wherein the fibres comprising composite filaments and the synthetic and/or natural fibres are provided in separate yarn or thread. Advantageously, the textiles as hereinbefore described may be used as a bleach activator.

The textile provided in accordance with the present invention will have a unique combination of physical, aesthetic and tactile properties. These properties can be adjusted through the optimisation of the weight ratio of the cellulose to the cellulose acetate in the composite filaments and/or by altering the fibre morphology, for example the denier, cross-sectional shape and degree of elongation during the spinning of the fibres.

The denier per filament may be from about 0.1 to about 100 g/9000m. Preferably, the denier per filament is from about 0.3 to about 50 g/9000m or from about 0.5 to about 25 g/9000m.

The cross-sectional shape may be selected from flat, circular, elliptical, triangular, hexagonal, rounded triangular, trilobal, lobular, mushroom-shaped, dog-bone-shaped, ribbon-shaped, star-shaped, hollow/tubular and collapsed tube.

The degree of elongation may be from about 0% to about 100%, from about 0% to about 75% or from about 0% to 50%.

Also provided in accordance with the present invention is a garment or soft furnishing made at least partly from the textile as hereinbefore described. Also provided in accordance with the present invention is a process for manufacturing the fibres used as a bleach activator as hereinbefore described, comprising: providing a solution dope comprising a blend of cellulose and cellulose acetate in an ionic liquid or in N-methylmorpholine-N-oxide; and spinning the solution dope into a coagulant to generate fibres.

The use of ionic liquids and N-methylmorpholine-N-oxide (NMMO) for dissolving cellulose and other polymers is known in the art. A wide range of ionic liquids are suitable for dissolving cellulose and cellulose acetate to form a solution dope and for spinning fibres therefrom. Suitable ionic liquids include those based on imidazole, pyrrole, thiazole, or pyrazole cations in combination with halogen, phosphite, carboxylate or metal chloride anions. Particularly preferred ionic liquids of this type include 1 -butyl-3-methylimidazolium chloride (BMIM-CI), 1 -butyl-3-methylimidazolium acetate (BMIM-Ac) and 1 -ethyl-3-methylimidazolium acetate (EMIM-Ac). Suitable ionic liquids also include those comprising a conjugate acid formed from a strong organic base, for example a substituted amidine or guanidine, in combination with a weaker Bronsted acid, for example a carboxylic acid. Particularly preferred ionic liquids of this type include 1 ,1 ',3,3'-tetramethylguanidinine carboxylates, 1 ,8- diazabicyclo[5.4.0]undec-7-ene carboxylates and 1 ,5-diazabicyclo[4.3.0]non-5-ene carboxylates.

The solution dope may also comprise a suitable co-solvent, for example an aprotic solvent. Examples of suitable co-solvents include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), tetrahydrofuran (THF), and dioxane. The co-solvent may aid dissolution of the cellulose and cellulose acetate. A particularly preferred co- solvent is DMSO.

Where a co-solvent is used, the ratio of the ionic liquid or NMMO to the co-solvent may be selected to ensure dissolution of both the cellulose and cellulose acetate, whilst providing a solution suitable for spinning into fibres.

The weight ratio of the cellulose to the cellulose acetate in the solution dope may be from 99.9:0.1 to 0.1 :99.9, from 99:1 to 1 :99, from 95:5 to 5:95, from 90:10 to 10:90, from 80:20 to 20:80, from 70:30 to 30:70, or from 60:40 to 40:60. The weight ratio of the cellulose to the cellulose acetate in the solution dope may be from 99.9:0.1 to 50:50, from 90:10 to 50:50, from 80:20 to 50:50, from 70:30 to 50:50, or from 60:40 to 50:50.

Typically, the solution dope comprises a solids content of up to about 50% by weight, up to about 45% by weight, up to about 40% by weight, up to about 35% by weight, up to about 30% by weight, up to about 25% by weight, or up to about 20% by weight. Preferably the solution dope comprises a solids content of from about 5% by weight to about 25% by weight, or from about 10% by weight to about 20% by weight.

The solution dope is preferably spun using a spinneret.

The coagulant may be any suitable non-solvent. Preferably, the coagulant comprises water, methanol and/or ethanol. Water is a particularly preferred coagulant. The process may further include the application of a spin finish, for example an emulsifier, lubricant and/or antistatic spin finish. Preferably, an emulsifier, lubricant and antistatic spin finish are applied.

The emulsifier may be selected from one or more of: alkali surfactants; amine surfactants; glycerol mono-di-fatty acid esters; sorbitan esters; polyoxyethylene sorbitan esters; polyglycerol esters, polyoxyethylene esters; polyoxyethylene ethers; polyoxyethylene polyol ether esters; polyoxyethylene amines; polyoxyethylene amides; partial polyol ester ethoxylates; sulfated vegetable oils; and sulfonated aromatic petroleum.

The lubricant may be selected from one or more of: mineral oils; alkyl esters; glycerides; silicone oils; waxes, for example paraffinic wax, naphthenic wax or polyolefinic wax; polyalkene glycols; polyoxalkylene glycols; and glycol esters.

The antistatic agent may be selected from one or more of: cationic species, including quaternary ammonium, pyridinium, imidazolium, or quinolinium species; phosphate alcohols; phosphate ethoxylates of fatty acids and fatty alcohols; amines; amides; organic sulfates; and organic sulfonates.

The process may further comprise drying of the fibres, preferably at raised temperatures, for example between 50°C and 150°C.

The process may further comprise dyeing the fibres with a disperse dye. The disperse dye may be any known suitable disperse dye. For example, the disperse dye may be selected from those previously outlined.

Also provided in accordance with the present invention is an activatable bleaching composition comprising fibres comprising one or more composite filaments of cellulose and cellulose acetate; and a peroxide and/or a peroxide precursor.

The peroxide/peroxide precursor may be selected from hydrogen peroxide, sodium perborate and sodium percarbonate.

The invention will now be more particularly described with reference to the following non-limiting figures and examples.

Figure 1 undyed fibres comprising composite filaments of cellulose and cellulose acetate

Figure 2: a scanning electron microscopy image of a fibre comprising composite filaments of cellulose and cellulose acetate

Figure 3: a graph showing the results for difference in Yl between control fibres and bleached fibres

Figure 4: a graph showing the results for percentage difference in Y (Yellow component from CMYK) between control fibres and bleached fibres Figure 5: a graph showing the results for percentage difference in K (Key component from CMYK) between control fibres and bleached fibres

Examples

Example 1 - Preparation of Fibres

Using standard wet-spinning equipment, fibres were spun from a solution of 8 wt. % cellulose (DP ~ 450) and 8 wt. % cellulose acetate (Eastman, CA-398-30), at 16% solids in EMIM-Ac:DMSO (26:74). A cluster head containing 7 x 560-orifice spinnerets with an orifice diameter of 40 μιτι was used. The spinnerets were submerged in a water coagulation bath heated to a temperature of 80°C. The fibres were washed extensively with water, dried at 120°C and reeled up.

The resulting fibres can be used as a bleach activator.

Figure 1 is a photograph of the resulting fibres once reeled up.

Figure 2 is a scanning electron microscopy (SEM) image of a resulting fibre.

Example 2 - Preparation of Fibres with Varying Cellulose to Cellulose Acetate Ratios Using standard wet-spinning equipment, fibres were spun from solutions of cellulose (DP ~ 450) and cellulose acetate (Eastman, CA-398-30), at ratios of 100:0 (comparative), 0:100 (comparative), 90:10, 80:20, 70:30, 60:40 and 50:50, at 16% solids in EMIM-Ac:DMSO (50:50). A cluster head containing 7 x 560-orifice spinnerets with an orifice diameter of 40 μιτι was used. The spinnerets were submerged in a water coagulation bath heated to a temperature of 80°C. The fibres were washed extensively with water, dried at 120°C and reeled up.

The fibres resulting from the solutions with cellulose to cellulose acetate ratios of 90:10, 80:20, 70:30, 60:40 and 50:50 can be used as a bleach activator.

Example 3 - Fibres as a Bleach Activator

Preparation of Fibres

Using standard wet-spinning equipment, fibres were spun from solutions of cellulose (DP ~ 450) and/or cellulose acetate (Eastman, CA-398-30), at ratios of 100:0 (comparative), 0:100 (comparative), and 50:50 (according to the invention), at 16% solids in EMIM-Ac:DMSO (50:50). A cluster head containing 7 x 560-orifice spinnerets with an orifice diameter of 40 μιτι was used. The spinnerets were submerged in a water coagulation bath heated to a temperature of 80°C. The fibres were washed extensively with water and dried at 120°C.

Staining of Fibres A hot tea solution was prepared by adding 3.3% granulated tea into hot water and steeping it for 5 minutes. The fibres as prepared above were stained in the hot tea solution for 5 minutes. After staining, the fibres were air dried for 12 hours.

Bleaching of Fibres

The stained fibres were bleached using hydrogen peroxide at 6% on the weight of fibre (OWF) with ethylenediaminetetraacetic acid (EDTA) stabiliser added at 2% OWF and a pH of around 10 - 10.5. Bleaching was performed at room temperature for 45 minutes with continuous stirring and a bleaching solution (hydrogen peroxide + EDTA) to fibre ratio of 15:1 . After bleaching, the fibres were washed in hot water (~95°C) for 15 minutes followed by cold water for 10 minutes. The fibres were then air dried for 12 hours.

Control bleaching experiments for each of the three fibre types were also carried out according to the above procedure except that the bleaching solution was replaced with water.

Determination of Bleach Activation

CMYK values, optical density (OD) values and CIE L ^* a ^* b ^* colour space data were measured using an X-Rite Densitometer for the stained fibres before and after bleaching (for both the control fibre samples and the bleached fibre samples).

As the tea-stained fibres were predominantly yellow, this colour was focussed on from the CMYK values recorded. Yellowness Index (Yl) values were also calculated from the CIE L ^* a ^* b ^* colour space data according to standard test method ASTM E313. The higher the Yl value, the more staining was present.

Yl was calculated using the following equation:

Y

X, Y and Z are CIE tristimulus values (calculated based on CIE l ^* a ^* b ^* values)

Cx and Cz are coefficients which are dependent on the illuminant and observer angle as indicated in the table below:

Coefficients for D65 standard illuminant and observer angle of 10 ^c

Cx = 1 .3013

Cz = 1 .1498

To determine the effectiveness of the bleaching process for each of the three fibre types, the difference between the colour/value change (Y and K from CMYK, and Yl) of the control fibres and the bleached fibres, was calculated for Yl, and Y and K from CMYK, according to the below formulae.

Difference in Yl between control fibres and bleached fibres:

(YIBs - YIB _W ) - (YICs - YIC _W )

where: YIBs = Yl of stained fibres prior to bleaching (prewash)

YIBw = Yl of stained fibres after bleaching (washed)

YICs = Yl of stained fibres for control (prewash)

YICw = Yl of stained fibres after control wash (water only)

Percentage difference in Y (Yellow component from CMYK) between control fibres and bleached fibres:

100 100

«YB _S - YB _W ) X f^) - «YC _S - YC _W ) X— ) where:

YBs = Y value of stained fibres prior to bleaching (prewash)

YBw = Y value of stained fibres after bleaching (washed)

YCs = Y value of stained fibres for control (prewash)

YCw = Y value of stained fibres after control wash (water only)

Percentage difference in K (Key component from CMYK) between control fibres and bleached fibres:

100 100

«KB _S - KB _W ) X— ) - {{KC _S - KC _W ) X— ) where:

KBs = K value of stained fibres prior to bleaching (prewash)

KBw = K value of stained fibres after bleaching (washed)

KCs = K value of stained fibres for control (prewash)

KCw = K value of stained fibres after control wash (water only) The results for difference in Yl between control fibres and bleached fibres are shown in Table 1 .

Table 1

These results are displayed graphically in Figure 4.

The results for percentage difference in K (Key component from CMYK) between control fibres and bleached fibres are shown in Table 3. Table 3

Fibre Type % Difference in K

100% Cellulose (comparative) 15.87

Cellulose and Cellulose Acetate (50:50) 22.16

100% Cellulose Acetate (comparative) 25.59

These results are displayed graphically in Figure 5.

The above results show that the bleaching process is more effective when cellulose acetate is present in the fibres. This is highlighted by the difference in Yl between control fibres and bleached fibres for the 100% cellulose (comparative) fibres and the 50:50 cellulose:cellulose acetate fibres, which had Yl values of 2.45 and 21 .97 respectively. A similar trend was observed for the Y and K values.

As hydrogen peroxide has low bleaching effectiveness at low temperatures and without a bleach activator present, it can be concluded that the greater bleaching efficiency of the fibres containing cellulose acetate is due to the cellulose acetate component acting as a bleach activator via the mechanism described hereinbefore.