CA2390130A1 - Method of treating fabric - Google Patents

Abstract

A method of treating fabric comprising dyed cellulosic fibres to increase its photostability comprises applying to the fabric a substance which is absorbed into and/or coated on to the fibres such that the diffusion of atmospheric oxygen into and/or within the fibres is inhibited. The method may be carried out as part of a laundering process or an industrial textile treatment. The method is particurlarly effective when the compound is used in conjuction with a sunscreen such as a benzotriazole.

Description

METHOD OF TREATING FABRIC
This invention relates to a method of treating fabric. In particular, the invention s relates to a method of treating fabric comprising dyed cellulosic fibres so as to increase its photostability. The invention also relates to the use of certain substances for increasing the photostability of dyed cellulosic fibres, to textile material treated with the substances and to fabric care compositions comprising the substances.
1o Cellulosic fibres such as cotton, viscose, Tencel~ and ModalO, are constructed from polyglucosan chains arranged into amorphous and crystalline regions (see, for example, Cellulose, Krassig, H. A. Gordon and Breach Science Publishers, Switzerland 1993). When these materials are ~s dyed for use in garments, the dye is predominantly situated in the amorphous region of the structure. The nature of the amorphous environment is therefore important in controlling the behaviour of dyes in dyed cellulosic garments.
2o Unfortunately, when dyed cellulosic fabric is exposed to sunlight, conventionally used dyes tend to photodegrade and the fabric becomes faded. UV light causes some of the fading and this may be reduced by applying UV sunscreens to the fabrics. However, for many dyes the majority of fading takes place with visible light, and there is no widely 2s applicable method to stop or reduce this fading. While some dyes are resistant to fading, others, particularly those used for garments, are prone to fading and fading is accelerated by wearing such garments out of doors or drying washed garments outdoors. It is particularly advantageous to provide a process for reduction of fading as part of a domestic laundering operation rather than as a one-off industrial treatment.
The key reaction of dyes in visible light which is responsible for fading of s dyed fabrics is thought to be the reaction of a photoexcited state of the dye with oxygen to form a reactive oxygen species (ROS):
d ~'g ' dye*+ 02~ products + ROS
1o This ROS may then degrade further dye molecules. Previous approaches to this problem have concentrated on preventing photo-exitation of the dye by adsorbtion of incident + UV light.
It is an obj ect of the present invention to increase the photostability of dyed 15 cellulosic fibres and, thus, reduce the tendency of fabric made from such fibres to fade. The term "photostability", as used herein, refers to the chemical stability of the dye in the cellulosic product on exposure to natural sunlight in the presence of atmospheric oxygen.
2o It is a further object of the invention to provide a system which provides colour care benefits for fabrics.
Accordingly, the present invention provides the use of a substance which is absorbed into and/or coats cellulosic fibres, to increase the photostability of 2s a fabric which comprises dyed cellulosic fibres, by inhibiting the diffusion of atmospheric oxygen into and/or within the fibres.

In another aspect, the invention provides textile material comprising a fabric which comprises dyed cellulosic fibres, wherein the fabric has been treated with a sunscreen and a substance which is absorbed into and/or coats the fibres such that the diffusion of atmospheric oxygen into and/or within the fibres is inhibited.
The textile material of the invention is suitable for use in all environments and, for example, may be in the form of a garment or a sheet suitable for making into a garment. Alternatively, the textile material may be more 1o rigid and may be suitable for use in other applications where more rigid fabrics are used such as in automative textiles or for heavy duty outdoor use (eg, shop awnings). Embodiments of the invention which relate to the treatment of garments are preferred.
~5 Further provided by the invention, in another aspect, is a fabric care composition comprising a sunscreen and a substance which is capable of being absorbed into and/or of coating cellulosic fibres such that the diffusion of atmospheric oxygen into and/or within the fibres is reduced, together with a textile compatible carrier which facilitates contact between 2o the substance and the fabric. This is believed to further reduce the extent of photo-fading.
The dyed cellulosic fibres which may be treated according to the invention include, for example, cotton, viscose and Tencel~. The cellulosic fibres 25 may form all or part of a fabric which is treated according to the invention.
Where the fabric is not completely of cellulosic fibres (that is to say, for example, not 100% cotton), the remaining fibres in the fabric may be those conventionally used in the art such as polyester and polyamide, for example, and mixtures thereof. Preferably, the fabric treated according to the invention comprises from 50% to 100% cotton, more preferably from 75% to 100% cotton.
s The fabric which is treated in the method of the invention may be woven, non-woven or knitted. However, when the cellulosic fibres comprise cotton, the fabric is preferably woven.
The invention is preferably applied to cellulosic fibres dyed with a dye to which is at least partly absorbed into the amorphous regions in the fibres, although it may be applied to fibres wherein some of the dye is present at the surface of the fibres.
Without wishing to be bound by theory, it is believed that the present 15 invention increases photostability at least partly by the substance acting as a physical barrier to inhibit diffusion of atmospheric molecular oxygen into the fibres and thus inhibiting reaction of oxygen with the dye. Hence, the substance may be considered as acting as a physical barrier to the diffusion of molecular oxygen into and/or within the fibres. Therefore, the invention 2o can be expected to be effective with many different substances and classes of dye which are susceptible to photodegradation in the presence of oxygen.
The fabric treated according to the invention may be dyed with a single dye, a mixture of dyes or may comprise some parts of fibres treated with one dye or mixture of dyes and other parts or fibres treated with another dye or 25 another mixture of dyes. Thus, the fabric may have a single colour or different colours.

It has been found to be particularly advantageous to treat the fabrics according to the invention together with a sunscreen. Suitable sunscreens for use on fabrics are well-known to those skilled in the art and include those described in Oxidation Inhibition in Organic Materials, eds Pospisil et 5 al, CRC Press 1990 ISBN 0-8493-4767-X(Vl), 0-8493-4768-8 (V2).
Sunscreens may be used in the invention either alone or in combination.
Preferred sunscreen include benzotriazoles. The sunscreen may be applied to the fabric before treatment with the substance in the invention, at the same time as the treatment with the substance or after the treatment with the 1o substance. The combination of the use of a sunscreen and the compound of the invention provides a surprisingly good improvement in the photostability of dyed fabrics. The sunscreen is preferably applied to the fabric to give an amount of up to 1 % by weight on weight of fabric (owfJ.
The weight ratio of substance to sunscreen applied to the fabric preferably lies in the range of 5,000:1 to 5:1, more preferably 500:1 to 10:1.
The method of the invention may be carried out as part of a laundering process or an industrial textile treatment. A number of conventional methods of deposition are suitable for use in the invention. Laundering 2o processes most preferably comprise domestic laundering processes. When used in a domestic laundering process, the substance may be in the form of the fabric care composition of the invention. The fabric care composition of the invention may be a main wash detergent composition, in which case the textile compatible carrier may include a detergent (such as anionic, non-ionic and cationic surfactants, for example) and the composition may include other conventional components sometimes contained in such compositions (such as enzymes, optical brighteners, soil release polymers, suds suppressors and anti-redeposition agents, for example). Alternatively, the fabric care composition may be adapted for use in the rinse cycle of a laundering process, in which case the textile compatible carrier may be a cationic softener, for example, and the composition may contain other components that are conventionally present in compositions of this type.
Preferably, the fabric care composition andlor the substance are adapted such that at least 5.0% by weight on weight of fabric, more preferably 5.0%
to 20% of the substance remains absorbed into and/or coated onto the fibres of the fabric after a conventional laundering process.
1o In the context of the present invention the term "textile compatible Garner"
is a component which can assist in the interaction of the substance with the fabric. The carrier can also provide benefits in addition to those provided by the first component e.g. softening, cleaning etc. The carrier may be a water or a detergent-active compound or a fabric softener or conditioning compound or other suitable detergent or fabric treatment agent.
If the composition of the invention is to be used in a laundry process as part of a conventional fabric treatment product, such as a detergent composition, the textile-compatible carrier will typically be a detergent-active compound.
2o Whereas, if the fabric treatment product is a rinse conditioner, the textile-compatible carrier will be a fabric softening and/or conditioning compound.
If the composition of the invention is to be used before, or after, the laundry process it may be in the form of a spray or foaming product.
In the invention, the composition of the invention is preferably used to treat the fabric in the rinse cycle of a laundering process. The rinse cycle preferably follows the treatment of the fabric with a detergent composition.

Detergent Active Compounds If the composition of the present invention is in the form of a detergent composition, the textile-compatible carrier may be chosen from soap and non-soap anionic, cationic, nonionic, amphoteric and zwitterionic detergent active compounds, and mixtures thereof.
Many suitable detergent active compounds are available and are fully described in the literature, for example, in "Surface-Active Agents and Detergents", Volumes I and II, by Schwartz, Perry and Berch.
The preferred textile-compatible carriers that can be used are soaps and synthetic non-soap anionic and nonionic compounds.
1s Anionic surfactants are well-known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly linear alkylbenzene sulphonates having an alkyl chain length of C8-C 15; primary and secondary alkylsulphates, particularly C8-C~5 primary alkyl sulphates; alkyl ether sulphates; olefin sulphonates; alkyl xylene sulphonates; dialkyl 2o sulphosuccinates; and fatty acid ester sulphonates. Sodium salts are generally preferred.
Nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C8-C2o aliphatic alcohols ethoxylated 2s with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the Coo-C~5 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Non-ethoxylated nonionic surfactants include alkylpolyglycosides, glycerol monoethers, and polyhydroxyamides (glucamide).
Cationic surfactants that may be used include quaternary ammonium salts of s the general formula R1R2R3R4N+ X- wherein the R groups are independently hydrocarbyl chains of C~-C22 length, typically alkyl, hydroxyalkyl or ethoxylated alkyl groups, and X is a solubilising cation (for example, compounds in which R~ is a C8-C22 alkyl group, preferably a C8-C1o or C12-C~4 alkyl group, R2 is a methyl group, and R3 and R4, which may be the io same or different, are methyl or hydroxyethyl groups); and cationic esters (for example, choline esters) and pyridinium salts.
The total quantity of detergent surfactant in the composition is suitably from 0.1 to 60 wt% e.g. 0.5-55 wt%, such as 5-SOwt%.
is Preferably, the quantity of anionic surfactant (when present) is in the range of from 1 to 50% by weight of the total composition. More preferably, the quantity of anionic surfactant is in the range of from 3 to 35% by weight, e.g. S to 30% by weight.
Preferably, the quantity of nonionic surfactant when present is in the range of from 2 to 25% by weight, more preferably from 5 to 20% by weight.
Amphoteric surfactants may also be used, for example amine oxides or 2s betaines.

The compositions may suitably contain from 10 to 70%, preferably from 15 to 70% by weight, of detergency builder. Preferably, the quantity of builder is in the range of from 15 to 50% by weight.
s The detergent composition may contain as builder a crystalline aluminosilicate, preferably an alkali metal aluminosilicate, more preferably a sodium aluminosilicate.
The aluminosilicate may generally be incorporated in amounts of from 10 to 70% by weight (anhydrous basis), preferably from 25 to 50%.
Aluminosilicates are materials having the general formula:
0.8-1.5 M20. A1203. 0.8-6 Si02 1 s where M is a monovalent canon, preferably sodium. These materials contain some bound water and are required to have a calcium ion exchange capacity of at least 50 mg Ca0/g. The preferred sodium aluminosilicates contain 1.5-3.5 Si02 units in the formula above. They can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply 2o described in the literature.
Fabric Softening and/or Conditioner Compounds If the composition of the present invention is in the form of a fabric 25 conditioner composition, the textile-compatible carrier will be a fabric softening and/or conditioning compound (hereinafter referred to as "fabric softening compound"), which may be a cationic or nonionic compound.

The softening and/or conditioning compounds may be water insoluble quaternary ammonium compounds. The compounds may be present in amounts of up to 8% by weight (based on the total amount of the composition) in which case the compositions are considered dilute, or at 5 levels from 8% to about 50% by weight, in which case the compositions are considered concentrates.
Compositions suitable for delivery during the rinse cycle may also be delivered to the fabric in the tumble dryer if used in a suitable form. Thus, 1o another product form is a composition (for example, a paste) suitable for coating onto, and delivery from, a substrate e.g. a flexible sheet or sponge or a suitable dispenser during a tumble dryer cycle. The composition of the invention may be in the form of such a coated substrate.
Suitable cationic fabric softening compounds are substantially water-insoluble quaternary ammonium materials comprising a single alkyl or alkenyl long chain having an average chain length greater than or equal to C2o or, more preferably, compounds comprising a polar head group and two alkyl or alkenyl chains having an average chain length greater than or equal 2o to C14. Preferably the fabric softening compounds have two long chain alkyl or alkenyl chains each having an average chain length greater than or equal to C16. Most preferably at least 50% of the long chain alkyl or alkenyl groups have a chain length of CI8 or above. It is preferred if the long chain alkyl or alkenyl groups of the fabric softening compound are predominantly linear.
Quaternary ammonium compounds having two long-chain aliphatic groups, for example, distearyldimethyl ammonium chloride and di(hardened tallow alkyl) dimethyl ammonium chloride, are widely used in commercially available rinse conditioner compositions. Other examples of these cationic compounds are to be found in "Surface-Active Agents and Detergents", Volumes I and II, by Schwartz, Perry and Berch. Any of the conventional types of such compounds may be used in the compositions of the present s invention.
The fabric softening compounds are preferably compounds that provide excellent softening, and are characterised by a chain melting L(3 to La transition temperature greater than 25°C, preferably greater than 35°C, most preferably greater than 45°C. This L(3 to La transition can be measured by DSC as defined in "Handbook of Lipid Bilayers", D Marsh, CRC Press, Boca Raton, Florida, 1990 (pages 137 and 337).
Substantially water-insoluble fabric softening compounds are defined as Is fabric softening compounds having a solubility of less than 1 x 10-3 wt %
in demineralised water at 20°C. Preferably the fabric softening compounds have a solubility of less than 1 x 10-4 wt%, more preferably less than 1 x 10~
8 to 1 x 10-6 wt%.
2o Especially preferred are cationic fabric softening compounds that are water-insoluble quaternary ammonium materials having two C12_22 alkyl or alkenyl groups connected to the molecule via at least one ester link, preferably two ester links. An especially preferred ester-linked quaternary ammonium material can be represented by the formula II:

s R1 N+ R3-T-Rz (II) (CHz)p-T-Rz wherein each R~ group is independently selected from C,_4 alkyl or hydroxyalkyl groups or Cz_4 alkenyl groups; each Rz group is independently selected from C8_z8 alkyl or alkenyl groups; and wherein R3 is a linear or is branched alkylene group of 1 to 5 carbon atoms, T is O O
20 -O-C- or -C-O-;
and p is 0 or is an integer from 1 to 5.
2s Di(tallowoxyloxyethyl) dimethyl ammonium chloride and/or its hardened tallow analogue is especially preferred of the compounds of formula (II).
A second preferred type of quaternary ammonium material can be represented by the formula (III):

s (III) (Ri)3N+-(CH2)p CHZOOCRZ
wherein Rl, p and R2 are as defined above.
io It is advantageous if the quaternary ammonium material is biologically biodegradable.
Preferred materials of this class such as 1,2-bis(hardened tallowoyloxy)-3-is trimethylammonium propane chloride and their methods of preparation are, for example, described in US 4 137 180 (Lever Brothers Co). Preferably these materials comprise small amounts of the corresponding monoester as described in US 4 137 180, for example, 1-hardened tallowoyloxy-2-hydroxy-3-trimethylammonium propane chloride.
2s Other useful cationic softening agents are alkyl pyridinium salts and substituted imidazoline species. Also useful are primary, secondary and tertiary amines and the condensation products of fatty acids with alkylpolyamines.
The compositions may alternatively or additionally contain water-soluble cationic fabric softeners, as described in GB 2 039 556B (Unilever).
The compositions may comprise a cationic fabric softening compound and 3o an oil, for example as disclosed in EP-A-0829531.

The compositions may alternatively or additionally contain nonionic fabric softening agents such as lanolin and derivatives thereof.
Lecithins are also suitable softening compounds.
Nonionic softeners include L(3 phase forming sugar esters (as described in M Hato et al Langmuir 12, 1659, 1666, ( 1996)) and related materials such as glycerol monostearate or sorbitan esters. Often these materials are used in conjunction with cationic materials to assist deposition (see, for example, GB 2 202 244). Silicones are used in a similar way as a co-softener with a cationic softener in rinse treatments (see, for example, GB 1 549 180).
The compositions may also suitably contain a nonionic stabilising agent.
Suitable nonionic stabilising agents are linear C8 to C22 alcohols alkoxylated with 10 to 20 moles of alkylene oxide, Coo to C2o alcohols, or mixtures thereof.
Advantageously the nonionic stabilising agent is a linear C8 to Cz2 alcohol 2o alkoxylated with 10 to 20 moles of alkylene oxide. Preferably, the level of nonionic stabiliser is within the range from 0.1 to 10% by weight, more preferably from 0.5 to 5% by weight, most preferably from 1 to 4% by weight. The mole ratio of the quaternary ammonium compound and/or other cationic softening agent to the nonionic stabilising agent is suitably 2s within the range from 40:1 to about 1:1, preferably within the range from 18:1 to about 3:1.

The composition can also contain fatty acids, for example:
C8 to C24 alkyl or alkenyl monocarboxylic acids or polymers thereof.
Preferably saturated fatty acids are used, in particular, hardened tallow C1~
to C18 fatty acids. Preferably the fatty acid is non-saponified, more s preferably the fatty acid is free, for example oleic acid, lauric acid or tallow fatty acid. The level of fatty acid material is preferably more than 0.1 % by weight, more preferably more than 0.2% by weight. Concentrated compositions may comprise from 0.5 to 20% by weight of fatty acid, more preferably 1 % to 10% by weight. The weight ratio of quaternary ammonium material or other cationic softening agent to fatty acid material is preferably from 10:1 to 1:10.
The fabric conditioning compositions may include silicones, such as predominately linear polydialkylsiloxanes, e.g. polydimethylsiloxanes or 1 s aminosilicones containing amine-functionalised side chains; soil release polymers such as block copolymers of polyethylene oxide and terephthalate; amphoteric surfactants; smectite type inorganic clays;
zwitterionic quaternary ammonium compounds; and nonionic surfactants.
2o The fabric conditioning compositions may also include an agent which produces a pearlescent appearance, e.g. an organic pearlising compound such as ethylene glycol distearate, or inorganic pearlising pigments such as microfine mica or titanium dioxide (Ti02) coated mica.
2s The fabric conditioning compositions may be in the form of emulsions or emulsion precursors thereof.

Other optional ingredients include emulsifiers, electrolytes (for example, sodium chloride or calcium chloride) preferably in the range from 0.01 to 5% by weight, pH buffering agents, and perfumes (preferably from 0.1 to 5% by weight).
s Further optional ingredients include non-aqueous solvents, perfume carriers, fluorescers, colourants, hydrotropes, antifoaming agents, antiredeposition agents, enzymes, optical brightening agents, opacifiers, dye transfer inhibitors, anti-shrinking agents, anti-wrinkle agents, anti-spotting agents, 1o germicides, fungicides, anti-oxidants, LJV absorbers (sunscreens), heavy metal sequestrants, chlorine scavengers, dye fixatives, anti-corrosion agents, drape imparting agents, antistatic agents and ironing aids. This list is not intended to be exhaustive.
~s Fabric Treatment Products The composition of the invention may be in the form of a liquid, solid (e.g.
powder or tablet), a gel or paste, spray, stick or a foam or mousse.
Examples including a soaking product, a rinse treatment (e.g. conditioner or 2o finisher) or a mainwash product. The composition may also be applied to a substrate e.g. a flexible sheet or used in a dispenser which can be used in the wash cycle, rinse cycle or during the dryer cycle. The composition may be in the form of the substrate with the composition applied thereto.
2s The industrial textile treatment methods of the invention generally involve large scale processes for treating fabric. The methods may be batch or continuous processes. They include dyeing of fibres or fabric, treating fabric prior to it being made up into garments and the treatment of garments after they have been made up. Industrial treatment methods include dry cleaning processes.
In order to allow it to be readily absorbed into and/or coated onto the s cellulosic fibres, the substance used in the invention is preferably soluble in a solvent. Substances which are water soluble can be used, such as substances having a water solubility of greater than 5% by weight, more preferably greater than 10% by weight. Alternatively, the substance may be soluble in a non-aqueous solvent (such as, for example, toluene).
1o Substances which are water-soluble are preferred for ease of application.
The substances used in the invention are desirably colourless (ie, transparent to visible light) so as not to interfere with the colour of the dyed fabric, although they may be coloured if their colour does not interfere with 1s the colour of the dyed fabric. Preferably, therefore, the materials have a molar absorption coefficient M<10 mol 1-~crri' within the range 400 to 800 nm. The substances are preferably substantially stable in sunlight, so as not to provide a further mechanism for fading of the dye in the fabric. The substances may have a degree of antioxidant or radical quenching activity in 20 order to further enhance the ability of the compounds to increase the photostability of the fabric by neutralising reactive oxygen species (ROS) before they can react with the dye molecules in the cellulosic fibres. The substances are preferably capable of forming a continuous layer around the fibres and, where the substances coat the fibres, they preferably form a 2s coating having a low permeability to oxygen (ie, a permeability constant of less than 1015[cm3][cm]/[cm2][s][Pa]). Preferably, the substances are neutral molecules, or mixtures thereof.

Substances which meet the requirements mentioned above include carbohydrates. Suitable carbohydrates include relatively low molecular weight substances, such as mono- and di- saccharides (eg, sucrose and cellobiose) for example. Higher molecular weight polysaccharides have s also been found to be useful in the present invention including tri- and higher saccharides eg, maltotriose. Other suitable substances include polysaccharides (eg, dextran). Dextrans are useful on account of their ready availability.
1o It is an essential feature of the substances which may be used in the invention that they must be capable of being absorbed into cellulosic fibres and/or of coating cellulosic fibres. Hence, the precise chemical nature of the substances can be widely variable.
1s A wide variety of substances may therefore be used in the present invention.
Other suitable substances, in addition to those mentioned above, include organic polymers, including homo- and co-polymers. Co-polymers may be random or block copolymers. Examples of organic polymers which may be used include, for example: polyacrylates, polymethacrylates and their 2o copolymers, eg, poly(methyl methacrylate), poly(ethyl methacrylate), poly(methyl acrylate), poly(ethyl acrylate), poly(propyl acrylate), poly(butyl acrylate) and acrylate copolymers with other acrylic or non-acrylic monomers, such as poly(ethyl methacrylate co methyl acrylate);
polystyrene and its copolymers, eg, copolymers of styrene with other olefins 2s such as butadiene and isoprene (for instance, polystyrene-polybutadiene-polystyrene block copolymers and polystyrene-isoprene-polystyrene block copolymers); and other polymers having relatively polar groups, eg, polyvinylacetate and polyvinylalcohol.

A single substance or a mixture of substances may be used in the present invention.
In the industrial textile treatment methods of the invention, the compounds are preferably applied to the fabric as a solution, by dipping or spraying for example, although other methods of application may be employed eg, using different solvents or the compound in liquid form. The substance may be applied to the fabric in conjunction with other components, such as a to sunscreen, for example. Alternatively, the sunscreen may be applied before or after the application of the substance.
The invention will now be described, by way of non-limiting illustration only, with reference to the following examples.

Example 1 Cotton dyed in strips with 16 different dyes was purchased from Veebee Tech (Harrogate, UK). The dyes chosen cover a wide range of typical dye s types.
no. name a /k Procion 1 Red HE-7B h drazone 0.5 2 Scarlet HE-3G h drazone and azo 0.5 3 Crimson HE-XL h drazone 0.5 4 Yellow HE-6G azo 1.0 5 Red HE-GXL h drazone 0.5 6 Blue HE-XL anthra uinone and h drazone2.0 7 Tur uoise H-A hthaloc anine S.0 8 Na HE-XL h drazone 1.0 Remazol 9 Red RB h drazone 1.0 10 Golden Yellow RNL azo 1.0 11 Brill Red RBS h drazone 2.0 12 Yellow FG azo 1.0 13 Oran a FR h drazone 2.0 14 Nav GG h drazone 2.0 15 Tur uoise G hthaloc anine 2.0 16 Black B h drazone 1.0 Table 1 Dyes used 1o Sucrose at various levels was padded onto the fabric from deionized water and dried. Electron Paramagnetic Resonance experiments using nitroxide spin probes in the amorphous region of cotton, show that addition of sucrose greatly reduces the mobility of the probes, ie, decreases the ability of oxygen to diffuse within the fibres.

The cotton was placed in a weatherometer (WOM) for 15 hours. The cotton was then removed, washed with deionized water and the colour change expressed in CIELAB OE units measured using a SpectraflashTM reflectance spectrometer. Lower values of DE represent less fading. The results are displayed in table 2. They show that reducing the mobility of oxygen within the fibres using a compound which is absorbed into and/or coated onto the fibres (sucrose in this case), significantly reduces the photo fading of a wide range of all the dyes. The benefit increases with the amount of sucrose added, although it will be appreciated that the higher levels of sucrose may be less preferred on account of the other changes that they impart to the fabric (eg, stiffness and water attraction).
d a number owf 6.44.2 6.87.25.2 2.63.13.1 4.22.54.1 3.83.73.0 1.85.3 0 7.94.4 7.16.34.7 1.93.93.9 4.02.93.4 2.92.12.2 1.74.6 1.8 7.63.8 6.65.44.0 1.93.32.5 3.52.23.3 2.71.81.0 1.43.9 7.4 4.12.3 3.82.72.9 1.12.41.7 3.62.11.3 0.50.70.6 0.72.4 19 2.51.2 1.91.51.9 0.71.90.9 2.11.81.1 0.20.71.0 0.41.9 40 2.11.9 2.92.32.2 1.13.21.8 1.5-1.40.9 0.91.50.7 2.73.6 80.6 ~ ~ ~ ~ ~ ~ ~ ~

Table 2 variation in fading with treatment. (% owf = weight percent of sucrose on the dry fabric) Example 2 The cotton strips used in example 1 were padded with sucrose, such that 2o there was 40% ow~ To one set 0.38% owf of a benzotriazole sunscreen (Tinuvin 571 (trade mark), ex Ciba Speciality Chemicals) was also padded on (from ethanol). They were placed in a weatherometer (WOM) for 40 hours, removed, washed in deionized water and the CIELAB OE units measured using a reflectance spectrometer. All showed a reduction in photofading, and the average reduction is presented in table 3.
treatment avers a DE

none 7.22 40% sucrose 2.53 40% sucrose & 0.38% Tinuvin 1.54 Table 3: Reduction in fading with treatments over 40 hours of fading.
When used on its own 0.38% Tinuvin 571 (trade mark) gives 25%
reduction in fading, which for the above would be an average OE of 5.42.
Thus, combination of substance and sunscreen gives a large reduction in photofading. This is much greater than any other known method.
Example 3 Various dextrans (obtained from Sigma Aldrich Chemical Co. Ltd., hereinafter referred to as "Aldrich") were padded onto the cotton containing the dyes of Example 1, such there was 8 and 40% owf. They were then irradiated in a WOM, removed, rinsed in water and the fading measured and compared to a control without treatments. The results are shown below:

Avera a DE

level and time of irradiation dextran used RMM* 8% 60 hours 40% 15 hours none control 9.1 3.7 9900 7.6 1.7 18100 6.9 1.7 71400 6.3 1.6 148000 6.5 1.6 494000 6.4 [ - 1.6 *RMM = Relative Molecular Mass All the dextrans at both levels significantly reduce the photofading of the dyed cotton.
Example 4 D-cellobiose (Aldrich) was padded onto the dyed cotton of Example 1 to give 9.0% owf. The cloth was irradiated in a WOM for 40 hours. The cloth was removed and compared to a control that had been irradiated without treatment. The cellobiose treated cloth gave an average OE of 6.6 compared to the control of 7.4. Again photofading had been inhibited.
Example 5 is Maltotriose hydrate (Aldrich) was padded onto dyed cotton of Example 1 (excluding dye 15) from a water solution containing 4.5% of the sugar, then dried. The cloth was irradiated in a WOM for 40 hours. The cloth was removed and compared to a control that had been irradiated without 2o treatment. The cellobiose treated cloth gave an average of DE of 4.0 compared to the control of 8Ø Again photofading had been inhibited.

Example 6 Polystyrene (Aldrich) was padded onto the dyed cotton of Example 1 from a toluene solution containing 10% of the polymer. The cloth was irradiated in s a WOM for 18 hours. The cloth was removed and compared to a control that had been irradiated without treatment. The polystyrene treated cloth gave an average DE of 3.4 compared to the control of 4.9. Again photofading had been inhibited.
Example 7 Polystyrene (block-polybutadiene-block-polystyrene; 28% styrene) (Aldrich) was padded onto the dyed cotton of Example 1 from a toluene solution containing 6.6% of the polymer. The cloth was irradiated in a ~s WOM for 15 hours. The cloth was removed and compared to a control that had been irradiated without treatment. The polystyrene treated cloth gave an average 0E of 2.9 compared to the control of 3.9. Again photofading had been inhibited.
2o Example 8 Polyvinylalchol ( 14 000 RMM) (Aldrich) was padded onto the dyed cotton of Example 1 from a water solution containing 10% of the polymer. The cloth was irradiated in a WOM for 18 hours. The cloth was removed and 25 compared to a control that had been irradiated without treatment. The polyvinyl alcohol treated cloth gave an average OE of 1.9 compared to the control of 3.9. Again photofading had been inhibited.

Example 9 The polymers listed in the following table (obtained from Aldrich) were padded onto the dyed cotton of Example 1 from a toluene solution, with and s without the benzotriazole sunscreen Tinuvin 571 (trade mark) (ex Ciba Speciality chemicals). The cloth was irradiated in a WOM for 24 hours.
The cloth was removed and compared to a control that had been irradiated without treatment.
Polymer all at 10% wt Tinuvin average 571, wt% 4E

of (eth 1 methac late-co-meth 1 ac late0 3.6 of eth 1 methac late-co-meth 1 ac late 0.53 2.4 of eth 1 methac late 0 3.2 of eth 1 methac late 0.62 2.5 of vin 1 acetate 0 3.4 of vin 1 acetate 0.67 2.4 of bu 1 ac late 0 3.5 of meth 1 ac late 0 3.4 polystyrene-block-polybutadiene-block 0.50 2.7 polystyrene 28 wt% st rene of s rene-block-iso rene-block of s 0.55 2.9 rene control 1 5.1 control 2 5.2 In all cases the photofading was reduced and when the polymer was combined with a sunscreen, the fading was reduced further.
Example 10 is A fabric conditioning composition according to the invention was prepared by adding a water dispersed polymer dispersion, Prinlin B7216A (trade mark) (obtained from Pierce and Stevens Corp, USA) to a standard fabric conditioning composition, Comfort (trade mark) (Unilever, UK).

Claims (10)

27

1. Use of a substance which is absorbed into and/or coats cellulosic fibres, to increase the photostability of a fabric which comprises dyed cellulosic fibres, by inhibiting the diffusion of atmospheric oxygen into and/or within the fibres.

2. Use as claimed in Claim 1, wherein a sunscreen is applied to the fabric before, during or after treatment with the substance.

3. Use as claimed in Claim 2, wherein the sunscreen is a benzotriazole.

4. Use as claimed in any one of Claims 1 to 3, wherein the substance is colourless and is substantially stable in sunlight.

5. Use as claimed in any one of Claims 1 to 4, wherein the substance comprises a carbohydrate.

6. Use as claimed in Claim 5, wherein the substance comprises a polysaccharide or an oligosaccharide.

7. Use as claimed in Claim 5, wherein the substance comprises a mono-or di- saccharide.

8. Use as claimed in Claim 7, wherein the substance comprises sucrose.

9. Use as claimed in any one of Claims 1 to 4, wherein substance is a polymer.

10. Use as claimed in any one of Claims 1 to 9, wherein the substance is applied to the fabric as part of a domestic laundering process or an industrial treatment process.