GB2371310A - Bleaching stains on fabrics using radical initiators - Google Patents

Abstract

The invention relates to bleaching compositions comprising radical initiators. More particularly the invention relates to laundry treatment compositions for the spot treatment of soiled articles and to a process using the said compositions. The invention provides a fabric treatment composition which comprises a radical initiator with a logP of greater than 2, which initiator produces active radicals having a logP of greater than 2, preferably greater than 4. The present invention further provides a method for the treatment of fabrics, which comprises applying to the fabric a composition according to the invention. Stains may be removed without affecting dyes on the fabrics.

Description

Fabric Treatment Composition

Technical Field : The present invention relates to bleaching compositions comprising radical initiators. More particularly the invention relates to laundry treatment compositions for the spot or other direct treatment of soiled articles and to a process using the said compositions.

Background of the Invention: Typical laundry stains contain chromophores based on carotenoids, phenolics and phytoestrogens. Radical photoinitiators are known as stain bleaches for laundry application. These are materials, which on exposure to light generate reactive radicals. In turn, these radicals cause chemical changes in the stain, which decolourise it.

Radical photo-initiators are well known in the unrelated fields of polymerisation and curing reactions.

Other types of radical initiators are known (such as thermal or chemical initiators) and use of these in bleaching and sewage or other effluent treatment has also been envisaged.

It is a well established problem in the field of laundry bleaching that compounds which can bleach stains will also have the capacity to bleach dyes present in the cloth.

Consequently, much effort has been spent in finding bleaches, which are effective against stains but are ineffective against dyes. This problem is especially difficult to solve in the context of porous fibres such as dyed cotton and other dyed cellulosics, particularly where these have been dyed with common dyestuffs based on strongly coloured azo-, anthroquinone or pthalocyanine compounds.

The swelling behaviour of cotton is discussed in'Cellulose - Structure Accessibility and Reactivity', Gordon and Breach Science Publishers and references therein. Commonplace solvents such as water and ethanol are effective at swelling the amorphous regions of cotton and other cellulosics.

UK Patent application no: 9917451.8, teaches that photoinitiators with high logarithm of octanol-water partition coefficient (log) give good stain bleaching with little dye damage on the fabric. This is highly desirous as consumers wish to remove stains without damaging their coloured fabric. The most preferred photoinitiators are those with logP values in excess of 4.0. It is believed that these high log ? materials do not pass into the amorphous regions of the cotton and consequently cause less damage than freely mobile initiators.

Many effective photoinitiators have logP values much lower than 4.0 but these are known to give some fabric dye damage particularly when used at high levels. It would be advantageous if these effective low log ? initiators could be used without causing damage. To some extent this can achieved by reducing the water or other transport activity

in use, either by use of selected anhydrous solvents or surfactants as carriers or by binding some or all of the water present in liquid crystal phases.

A further problem occurs if the initiator is to be used in an aqueous system. The presence of water increases the tendency of some initiators to cause damage whether they have been shown to have a high logP or a low logP.

A prior approach to this problem is disclosed in co-pending UK patent application UK 9929693.1. This teaches the use of radical terminators in conjunction with radical initiators to reduce dye damage. However the use of two active ingredients may not always be desirable, particularly for reasons of cost.

Brief Description of the Invention: We have found a new and effective approach to these problems. We have determined that those initiators, which lead to active radicals with a high logP, reduce dye damage without a corresponding reduction of stain bleaching.

Advantageously, and somewhat surprisingly, this reduction of damage is maintained even under wet conditions, i. e. under conditions where the radical initiator may enter the amorphous regions of the fibres.

Accordingly, the present invention provides a fabric treatment composition which comprises a radical initiator with a log ? of greater than 2, which initiator produces

radicals having a log ? of greater than 2, preferably greater than 3, more preferably greater than 4.

It is believed that, even under wet conditions (i. e. as typically found in the main wash cycle of domestic washing machines), formulations according to the present invention reduce the incidence of radical damage. It is believed that the passage and/or retention of the active radical into the regions of the fibres where the dye resides is prevented while allowing the radical to come into contact with the stain, which is essentially superficial. In preferred embodiments, both the initiator and the radical will have a logP above 3 and more preferably above 4.

The present invention further provides a method for the treatment of fabrics, which comprises applying to the fabric a composition according to the invention.

The invention further provides a main-wash formulation which comprises a fabric treatment composition according to the present invention.

Detailed Description of the Invention: The preferred radical initiators are photo and thermal initiators. The use of photo initiator systems is preferred as sunlight and other suitable sources of illumination are generally freely available. It is commonplace, for example, to dry laundered articles in sunlight.

Typical compositions will also comprise one or more surfactants.

Mode of application: The compositions may be contained in a wipe and the wipe used to physically remove stain and apply photo-initiator to it. Alternatively, the composition may be applied directly to the substrate being treated.

Surfactants, where present, may be employed in solid or liquid form. In some markets, liquid surfactants are preferred for ease of application. In other markets solid forms, particularly soft solids, will be preferred.

Preferably, these can take the form of soap or other nonsoap detergent bars, although embodiments of the invention may take the form of other applicator sticks.

A range of suitable application forms can be found in the art of deodorant sticks and other applicators.

A particularly preferred embodiment of the present invention will be in the form of a laundry main-wash detergent composition.

The initiator may be a perfume material or the carrier of a perfume material. Inclusion of the initiator in a final composition together with the perfume is advantageous as both classes of materials may require careful dosing and the composition is generally not subjected to heating once the perfume has been added.

The photo-initiator system must generally be stored in the absence of light of wavelength below 500nm, to avoid photo reaction. An opaque packaging is sufficient for this purpose.

Surfactant: When present, the surfactant may be chosen from soap and non-soap anionic, cationic, non-ionic, 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. Nonionic surfactants, particularly alkoxylated nonionics are preferred.

Nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C1O-Cls 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).

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-C15; primary and secondary alkylsulphates, particularly Cs-Cis primary alkyl sulphates ; alkyl ether sulphates ; olefin sulphonates; alkyl xylene sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.

Sodium salts are generally preferred.

Cationic surfactants that may be used include quaternary ammonium salts of the general formula R1R2R3R4N+ X-wherein the R groups are independently hydrocarbyl chains of Cl-C22 length, typically alkyl, hydroxyalkyl or ethoxylated alkyl groups, and X is a solubilising cation (for example, compounds in which Ri is a C8-C22 alkyl group, preferably a Cs-C1o or Cl. 2-CI4 alkyl group, R2 is a methyl group, and R3 and R4, which may be the same or different, are methyl or hydroxyethyl groups); and cationic esters (for example, choline esters) and pyridinium salts.

Amphoteric surfactants may also be used, for example amine oxides or betaines.

Radical Initiators:

The photo-initiators can be hydrogen abstraction radical photoinitiators. These include benzophenones, acetophenones, pyrazines, quinones and benzils.

However, bond cleavage photoinitiators are preferred.

Suitable bond cleavage radical initiators may be selected from the following groups: (a) alpha amino ketones, particularly those containing a benzoyl moiety, otherwise called alpha-amino acetophenones, for example 2-methyl 1-[4-phenyl]-2-morpholinopropan-1-one (Irgacure 907, trade mark, ex CIBA), (2-benzyl-2-dimethyl

amino-l- (4-morpholinophenyl)-butan-l-one (Irgacure 369, trade mark, ex CIBA) ; (b) alphahydroxy ketones, particularly alpha-hydroxy acetophenones, eg (1- [4- (2-hydroxyethoxy)-phenyl]-2-hydroxy- 2-methyl-l-propan-l-one) (Irgacure 2959, trade mark, ex CIBA), 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, trade mark, ex CIBA) ; 2-hydroxy-2-methyl-l-phenylpropan-l- one (Esacure m KL200 ex Lamberti SPA) ; and, oligomeric polyfunctional alpha-hydroxyketones (such as Esacure KIP150 ex Lamberti SPA) ; (c) phosphorus-containing photoinitiators, including monoacyl and bisacyl phosphine oxide and sulphides, for example 2-4-6- (trimethylbenzoyl) diphenyl-phosphine oxide, bis (2,4, 6-trimethylbenzoyl) -phenyl-phosphine oxide (Irgacure

819, trade mark ex CIBA), (2, 4, 6-trimethylbenzoyl) phenyl phosphinic acid ethyl ester (Lucerin TPO-L (trade mark) ex BASF) ;

(d) dialkoxy acetophenones ; particularly Benzildimethylketal (Esacure N KB1 ex Lamberti SPA) ; (e) alpha-haloacetophenones; (f) trisacyl phosphine oxides; and, (g) benzoin and benzoin-based photoinitiators.

Further suitable radical photoinitiators are disclosed in Wo 9607662 (trisacyl phosphine oxides), US 5399782 (phosphine sulphides), US 5410060, EP-A-57474, EP-A-73413 (phosphine oxides), EP-A-088050, EP-A-0117233, EP-A-0138754, EP-A0446175 and US 4559371.

Other suitable radical photoinitiators are disclosed in EP A-0003002 in the name of Ciba Geigy, EP-A-0446175 in the name of Ciba Geigy, GB 2259704 in the name of Ciba Geigy (alkyl bisacyl phosphine oxides), US 4792632 (bisacyl phosphine oxides), US 5554663 in the name of Ciba Geigy (alpha amino acetophenones), US 5767169 (alkoxy phenyl substituted bisacyl phosphine oxides) and US 4719297 (acylphosphine compounds).

Transition metal catalysts and complexes may also be used to initiate radicals.

Radical photoinitiators are discussed in general in A. F.

Cunningham, V. Desorby, K. Dietliker, R. Husler and D. G.

Leppard, Chemia 48 (1994) 423-426 and H. F. Gruber, Prog.

Polym. Sci. , 17, (1992), 953-1044.

The preferred radical photoinitiators become active when excited by radiation falling generally in the range 290-800 nm. For example, natural sunlight, which comprises light in this region, will be suitable for causing the radical photoinitiator to undergo one of the reactions described above.

Preferably, the radical photoinitiator has a maximum extinction coefficient in the ultraviolet range (290-400 nm) which is greater than 100 mol-llcm-l. Suitably, the radical photoinitiator is a solid or a liquid at room temperature.

Particularly preferrred photo-initiators include alpha hydroxy ketones, particularly those containing a benzoyl moiety.

Suitably, the radical photoinitiator is substantially colourless and gives non-coloured photo products upon undergoing one of the reactions set out above.

Optionally, the compositions comprise sensitisers such as thioxanthones, for example as described in EP-A-0088050, EP A-0138754.

The radical photoinitiators are preferably activated by ambient light eg, domestic lighting or sunlight. However, a separate light source (for example a tungsten filament or gas discharge tube) may be employed for activation of the photoinitiator.

In the alternative, the initiator may be a thermal initiator, which decomposes to form radicals on heating. As will be apparent, there will be some degree of overlap between the classes of initiator, which may be used in these two aspects of the invention. Some radical photoinitiators also decompose by heating (particularly at higher temperatures) and some thermal initiators decompose on exposure to light (particularly at shorter wavelengths).

Suitable thermal initiators include compounds comprising an azo-group or a peroxygen group. Preferred materials exclude those containing a peroxygen group and include those forming a carbon-centred radical rather than an oxygen-centred radical.

The thermal initiators are preferably stable at ambient temperature. Temperatures to which the thermal initiators should be heated to cause them to decompose are preferably

in the range of up to 100 C, more preferably from 35 C to 90oC, most preferably 35 C to 40oC. Heat may conveniently be applied by means available in the laundering environment such as by use of an iron or tumble drier.

The most preferred radical initiators, whether triggered by light or heat, are those which operate by a so-called 'cleavage'mechanism. These are generally advantageously free of side-products.

Preferred photo-initiators are those which function by the so-called'alpha-cleavage'mechanism. These photo-initiators are believed to cleave so as to produce an dye-inactive

carbonyl radical and an dye-active counter radical. As will be shown by way of example below it appears that under wet conditions the damage caused by the initiator is related to the logP of the counter radical. No corresponding correlation is believed to exist between the dye damage caused by the initiator and the logP of the carbonyl radical.

Compositions of the invention may further comprise radical terminators.

Main Wash Compositions: Main wash compositions according to the present invention may be liquids. The composition may also be in the form of a semisolid, tablet, powder or granule, which is dissolved in an aqueous medium when ready for use.

The total quantity of detergent surfactant in a main-wash composition is suitably from 0.1 to 60 wt%, eg 0.5-55 wt%, such as 5-50 wt%.

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 55% by weight, eg 5 to 30% by weight.

Preferably, the quantity of anionic surfactant is in the range of from 3 to 35% by weight, eg 5 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 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.

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 M2O Alios. 0. 8-6 Si02 where M is a monovalent cation, preferably sodium. These materials contain some bound water and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g.

The preferred sodium aluminosilicates contain 1.5-3. 5 SiO2 units in the formula above. They can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature.

The invention will be further described with reference to the following non-limiting examples.

Examples : For all the examples, values given are the average of 4 experiments. CIELAB AE values of the cloths compared to the original untreated fabric were measured using a reflectance spectrometer.

Blue, red and black dyed cotton cloth for use in the examples was prepared by reactively dying with Remazol Brilliant Blue R, Procion Red HE-7B and Remazol Black B. The cloths contained 9. 3x10-s mol kg-1, 8. 3x10-s mol kg-l and 1. 5x10-4 mol kg-1 of dye respectively. These cloths are sensitive monitors of dye damage.

Separate samples of white cloth were heavily stained with carotene (ex. Equest, Newcastle GB). These cloths served as monitors of bleaching activity.

Unless specified initiators were obtained from commercial suppliers (Ciba Speciality Chemicals, BASF. Lamberti Spa and Aldrich).

Example 1 The cloth was dipped in ethanol containing 0.2% by weight of 2-hydroxy-4'-hydroxyethoxy-2-methylpropiophenone, the ethanol evaporated and then the cloth irradiated in

Weatherometer for 18 minutes. CIELAB AE values of the cloths

compared to the original untreated fabric were measured. The experiment was then repeated using the radical initiators listed in table 1. The average damage to the 3 colours are shown in table 1.

It can be seen from the table that while there is some correlation between the LogP of the initiator and the damage under dry conditions, the correlation is far weaker under wet conditions.

Initiator Log P of AE AE initiator Average Average dye damage dye damage dry-wet 2-hydroxy-4'-0. 84 8. 5 14. 2 hydroxyethoxy-2methylpropiophenone Dimethoxyphenyl-2.68 3.8 4.1 acetophenone 1-hydroxycyclohexyl 2.81 3.4 9. 6 phenyl ketone Benzoin methyl ether 2. 95 3. 7 5. 5 Benzoin ethyl ether 3.48 2.7 3.6 Diethoxyphenyl-3.74 2.3 3.0 acetophenone 2,4, 6- 4. 3 i. t 5. 0 trimethylbenzoylphenyl - phosphinic acid ethyl ester Phenyl bis (2,4, 6- 5. 8 1.1 7.1 trimethylbenzoyl) phosphine oxide Table 1-Average dye damage to red, green and black cotton cloth caused by application of 0.2% of a radical photoinitiator.

All the initiators listed in table 1 function via an alpha cleavage mechanism to produce a carbonyl radical and a counter radical. The identity of the counter radical is given in table 2, also given is an estimation of the log ? of the radical.

In the wet the damage decreases as the logP of the counter radical increases. An excellent correlation is found between the damage in the wet and the logP of the counter radical.

(R=0. 80). No correlation is found with the logP value of the carbonyl radical, which is believed to be non-reactive in this context.

Initiator Counter radical Log P of #E counter Average radical dye damage - wet 2-hydroxy-4'- # 0. 0514. 2 hydroxyethoxy-2- (CHCOH methylpropiophenon e 1-1. 2 9. 6 hydroxycyclohexyl Cyclo- (CH2) 5 COH phenyl ketone Phenyl bis (2,4, 6-. 1.5 7.1 trimethylbenzoyl) (tPhCO) (Ph) P = 0 - phosphine oxide.

/Ph (R) P = 0 Dimethoxyphenyl- # 1.65 4.1 acetophenone (CH3O)2C Ph 2,4, 6- # 1. 8 5.0 trimethylbenzoylph (Ph)(CH3CH2O) P = O enyl-phosphinic acid ethyl ester Benzoin methyl. 1. 92 5.5 ether (CH3O) C (H) Ph Benzoin ethyl. 2. 45 3.6 ether (CH3CH2O)C(H)Ph Diethoxyhenyl- # 2. 71 3.0 acetophenone (CH3CH2O)CPh Table 2 log P values of the counter-radicals to the carbonyl radical formed by the photoinitiators.

Log P values of the radicals are estimated by assuming they

are identical to the equivalent C-H compound, i. e.

.

(CHCOH equivalent to propan-2-ol. For Phenyl bis (2, 4, 6trimethylbenzoyl)-phosphine oxide the molecule photoreacts twice to give two different counter radicals, the average log ? value of these two radicals is given. R is unknown and taken as methyl. Ph = phenyl and tPhCO = trimethylbenzoyl.

Example 2 The experiment of example 1 were repeated using -carotene stained white cotton. (Equest, Newcastle-u-Tyne, UK). All the initiators used bleached the stain.

Claims (13)

1. CLAIMS : 1. A fabric treatment composition, which comprises a radical initiator with a logP of greater than 2, which initiator produces active radicals having a log ? of greater than 2.
2. 2. A composition according to claim 1 wherein the composition is a liquid or soft solid.
3. 3. A composition according to any preceding claim, comprising an alkoxylated nonionic surfactant.
4. 4. A composition according to claim 3, wherein the surfactant is a liquid or solid ethoxylated alcohol.
5. 5. A composition according to any preceding claim, where the radical initiator is a photo or thermal initiator.
6. 6. A composition according to any preceding claim, wherein the initiator is a bond-cleavage photo-initiator.
7. 7. A composition according to claim 7, wherein the initiator is selected from: (a) alpha amino ketones, (b) alphahydroxy ketones, (c) phosphorus-containing photoinitiators, (d) dialkoxy acetophenones ; (e) alpha-haloacetophenones; (f) trisacyl phosphine oxides; (g) benzoin and benzoin-based photoinitiators, and,

   (h) mixtures thereof.
8. 8. A composition according to claim 7, wherein the radical photo-initiator becomes active when excited by radiation falling generally in the range 290-800 nm.
9. 9. A composition according to claim 7, wherein the radical photo-initiator has a maximum extinction coefficient in the ultraviolet range (290-400 nm) which is greater than 100 mol-llcm-1.
10. 10. A composition according to any preceding claim, further comprising one or more perfume components.
11. 11. A composition according to any preceding claim, further comprising a radical terminator.
12. 12. A method for the treatment of fabrics which comprises applying to the fabric a composition according to any of claims 1-11.
13. 13. A laundry main-wash composition comprising a composition according to any one of claims 1-11 and a detergency builder.