|Title of Invention||
A CLEANING COMPOSITION
|Abstract||The present invention relates to a cleaning composition comprising an immiscible liquid system having at least one liquid-liquid interface with an interfacial tension greater than 5 mN/m. By providing that the pH of the composition is above 7, an improved cleaning efficacy, particularly regarding the removal of tough stains like iron/humic acid stains, is obtained.|
|Full Text||FORM -2
THE PATENTS ACT, 1970 (39 of 1970)
(See Section 10)
A IMPROVED LIQUID CLEANING COMPOSITION
HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.
The invention relates to a cleaning composition comprising a non-toxic
and safe system of immiscible liquids with high interfacial tension having a pH
above 7 and which does not require the use of additional detergency benefit
agents, and an improved process/method of cleaning/washing fabric using the
Background and prior art:
Conventionally, fabric is cleaned using water and a detergent surfactant system which is known as wet cleaning. Surfactants adsorb on both fabric and soil and thereby reduce the respective interfacial energies and this facilitates removal of soil from the fabric. Alternatively it is done by a process called dry cleaning where organic solvents such as perchloroethylene (PCE), petroleum based or Stoddard solvents, chlorofluorocarbon (CFC)-113 and 1,1,1-trichloroethane are used, all of which are generally aided by a surfactant. The organic solvent helps in the removal of oily soil in the presence of detergents. Soil removal can be achieved by a small reduction in interfacial tension. The particulate soil is largely removed by providing agitation.
Most washing processes applied to fabrics involve a combination of physical, physico-chemical and chemical actions. Soil removal from fabrics is an extremely complex affair and to date there are no theories which give adequate account of the processes involved. One of the most important parameters in detergency is the temperature of the wash liquor. A second important parameter is the free calcium ion and active detergent level. Most soils respond positively to a decrease in free calcium ion concentration and to an increase in active detergent level. Another important parameter in detergency is the pH. In general, the lower the pH the poorer the physical cleaning will be.
Apart from physical and physico-chemical soil removal, bleaching and stain removal by chemical reaction can play an important role in fabric washing. Commercial fabric- washing products are generally formulated as an alkaline built detergent composition having a pH of about 7-11.0 in aqueous solution.
In dry cleaning formulations the pH used is usually from 5-9 to provide excellent cleaning and also minimise equipment corrosion and fabric damage.
Our earlier-filed co-pending application 469/Mum/2000 dated 23/5/2000 equivalent to WO-A-01/90474, published 29 November 2001 discloses a process of cleaning fabric using the liquid-liquid interface of at least two immiscible liquid phases with an interfacial tension greater than 5mN/m, under agitation, but does not teach any specific benefit of pH for specific stain removal.
There are many types of stains that are found on the fabric to be cleaned and certain of these require specific treatment to be removed. One of the commonly encountered stains is from a combination of iron (III) and humic acid. This stain is very commonly found and especially in the monsoon season, the humic acid present in the soil sequesters iron from crustal soil in water and leaves a red/brown stain on fabric with which it comes into contact. This stain is extremely difficult to remove using conventional wet or dry cleaning systems.
The object of the present invention is to formulate immiscible liquid systems that specifically remove tough stains e.g. iron-humic acid stains from fabric and improve detergency,
Our co-pending application 999/MUM/2001 of even date discloses a cleaning composition comprising an immiscible liquid system having at least one liquid-liquid interface with an interfacial tension greater than 5mN/m, characterized in that the less polar solvent in the system has a carbon chain length of at least 4, but does not teach any specific benefit of pH for specific stain removal.
Our co-pending application 1000/MUM/2001 of even date discloses a cleaning composition comprising an immiscible liquid system having at least one liquid-liquid interface with an interfacial tension greater than 5 mN/m, the less polar solvent in the system being a silicon with more than 3 SiO units, characterized in that the composition comprises from 0.001-20% of one or more benefit agents which are soluble in at least one of the phases of the liquid system, but does not teach any specific benefit of pH for specific stain removal.
Summary of the invention:
The applicants have found that efficient removal of tough stains is possible by cleaning a fabric under agitation using a washing/cleaning system comprising a liquid-liquid interface of at least two immiscible liquid phases with an interfacial tension greater than 5mN/m, said system having a pH ranging from above 7-12.
The applicants have developed a system with at least one immiscible phase and with high interfacial tension having a pH above 7 which provides superior tough stain cleaning.
Detailed description of the invention:
Thus according to one aspect of the present invention there is provided a cleaning/washing composition comprising an immiscible liquid system having an interfacial tension greater than 5mN/m, said composition having a pH above 7.
Interfacial tension may be measured using various techniques, such as sessile drop,pendant drop, spinning drop, drop volume or Wilhelmy plate method.For the
purposes of the present invention, interfacial tension is measured by the Wilhelmy plate method, using a Kruss Processor Tensiometer K12, at 25°C. For some systems, the interfacial tension may change whilst undergoing shearing forces typically encountered in a washing process, it is customary to refer to the interfacial tension under these conditions as a " dynamic interfacial tension"(DIFT) and may be measured by a maximum bubble pressure technique.
According to a preferred aspect of the invention the cleaning/washing composition comprises an immiscible liquid system with an interfacial tension greater than 5mN/m, said composition having a pH above 7, wherein the less polar solvent has a carbon chain length of at least 4 and/or is a silicone with more than 3 SiO units.
According to another preferred aspect the cleaning/washing composition comprises anjmmiscible liquid system with an interfacial tension greater than 10mN/m.having a pH in the range of above 7 to 12, wherein the less polar solvent has a carbon chain length of at least 4 and/or is a silicone with more than 3 SiO units, the concentration of the most polar liquid being from 10-90% (v/v).
According to a more preferred aspect of the present invention the cleaning/washing composition comprises an immiscible liquid system with an interfacial tension greater than 20mN/m, said composition having a pH in the range of above 7 to 12, wherein the less polar solvent has a carbon chainlength of at least 4 and/or is a silicone with more than 3 SiO units and selectively provided such that the.concentration of the most polar liquid is. 40-90% (v/v) for a period of at least 5 minutes during the wash process.
It is preferred that the carbon chain length of the less polar solvent is greater than 6, preferably greater than 12 and more preferably greater than 16.
According to another aspect of the present invention there is provided a process of cleaning fabric comprising agitating the fabric in the above disclosed immiscible liquid system having an interfacial tension greater than 5mN/m and a pH above 7.
Solvents that can be used include water, alcohols, esters, ethers, ketones, hydrocarbons, paraffins, aromatic solvents, halogenated solvents such as chloromethane, perchlorethylene(PERC), carbon tetrachloride, 1,1,2,-trtchloro-1,2,2,trifluoroethane,chlorobenzene, bromobenzene, heterocyclics etc. Mixtures of these can be used such that at least one interface exists and the interfacial tension is greater than 5 mN/m, preferably greater than 10mN/m.
The solvents that have a carbon chain length of at least 4, preferably,greater than 6 may be selected from branched and linear alkanes (chemical formula CnH2n+2 where n is at least 4), including but not limited to hexane, heptane, octane, nonane, decane, dodecance, tridecane, tetradecane, pentadecane etc. and mixtures thereof. Commercially available mixtures of this type include Isopar L (C11-C15 alkanes - ex-Exxon) and DF2000 (C11-C15 iso-alkanes;CAS# 90622-58-5ex-Exxon). Branched and linear alkenes with at least 4, preferably morer
than 6 carbon atoms including but not limited to octenes, nonenes, decenes, undecenes, dodecenes etc, with one or more double bonds and mixtures thereof may also be used.
Ethers including fluoroethers with at least 4 carbon atoms such as methoxy nonafluorobutane HFE7100 (ie. C4F9-OCH3) and ethoxy nonafluorobutane HFE-7200 (ie. C4F9-OC2H5), esters with at least 4 carbon atoms, such as dibutyl phthalate, dioctyl phthalate, C8-C24 saturated and/or unsaturated fatty acid methyl esters such as C10-C18 fatty acid methylesters like methyl laurate, methyl myristate, methyl stearate, methyl linoleate, methyl linolenate, and terpenes, such as limonene or mixtures thereof may be used.
The solvents with SiO units greater than 3 may be selected from polydimethyl
siloxane oils. Linear and cyclic siloxanes known as Lx and Dx where x is greater
than three are suitable for this technology. Specific examples include
octamethylcyclotetrasiloxane(D4) (ex-Dow Corning), decamethyl-
cyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), decamethyl-tetrasiloxane (L4) and dodecamethyl pentasiloxane(L5).
It is possible to incorporate other conventional detergent ingredients such as
surfactants, builders, anti redeposition agents, soil release polymers,
hydrotropes, enzymes, bleaches, fluorescers, perfumes etc. in the immiscible
The pH of the system should be above 7 and is preferably maintained in the range of above 7 to 12 , usually by the addition of conventional alkaline chemicals such as alkali metal carbonates or bicarbonates, amines, organic amines, hydroxyl amines etc.
Agitation can be provided by impellers that cover the vertical flow profile or radial flow profile or a combination of both so that thorough-mixing of the immiscible liquids take place. Agitation can be provided by impellers that are open curved turbine, turbine type propeller, axial flow turbine, flat blade turbine, inverted vane turbine, marine propeller etc.. This action may also be accompanied by a tumbling action. Optionally agitation can also be provided;by a combination of rotation and tumbling action. Other forms of agitation using gas jets or ultra sound may also be employed. Other forms of agitation generally known in the art can also be employed provided it ensures a good mixing of the immiscible liquid phases.
The nature of the invention, its objects and advantages will be more apparent from the ensuing description made with relation to non-limiting examples of the above identified various aspects of the invention.
Effect of immiscible liquid system on iron-humic acid stain removal: Test monitors (8x8 cm) were prepared by soaking non-fluorescent desized cotton (18 Nos.) for 12 hours in 360 ml of a mixture comprising a 1.2 g/l solution of humic acid procured from John Baker Inc. Colorado, USA (Lot no. 20301), 0.6 g/l solution of ferric chloride (FeCb) procured from Acros Organics, and 58.2 g/l English India china clay (kaolinite) and then drying on a flat surface. The reflectance of the fabrics was determined at 460nm, with uv excluded, using a Macbeth Colour-eye 7000 reflectometer (R460* initial).
Three 8x8 soiled iron humic acid soiled swatches were then washed using a detergent composition having a pH 10.5 (Example 1) whose formulation details are presented in Table 1. Washing was carried out using a laundrometer (Linitest, Atlas) at 45 rpm, 28°C for 45 min. The fabric was soaked tor 30 min in the detergent solution prior to washing. The fabrics were allowed to dry in air and
then the final reflectance at 460nm, with uv excluded, was determined using the same reflectometer.(R460*final).
The initial reflectance at 460 nm of three swatches soiled with iron-humic acid was determined using reflectometry as described in the above examples. The swatches were placed into a 500 ml., conical flask to which 60ml of perchloroethylene and 240 ml of water were added and maintained at pH 6.0 (Example 2), and at pH 10.5 (Example 3) by adding sodium carbonate. The conical flask was then agitated at 120rpm for 30 mins at ambient temperature using a reciprocating agitator, which facilitates efficient mixing of the liquids. Following washing the individual swatches were allowed to dry in air and the final reflectance values for the swatches determined using the Macbeth Colour-eye 7000 reflectometer. The difference in reflectance ∆R460* was determined by subtracting the initial reflectance from the final reflectance and the average result for the three swatches is given in Table 2.
The results in Table 2 illustrate that washing in oil /water systems having an alkaline pH provides an enhancement in the cleaning performance of oil /water cleaning systems for iron /humic acid stains.
Delta R460* value indicates the difference in reflectance values obtained by subtracting the initial reflectance of the soiled swab from the final reflectance of the swab after washing. The more is the cleaning efficiency, higher is the final reflectance, higher will be the Delta R460* values.
Higher Delta R460* values for the present system have been demonstrated in Table 2 where even the tough iron humic acid stains were seen to be removed more efficiently with the compositions at the selected pH range. Example 3 (of the present invention) having pH 10.5 is seen to have higher delta R460* values for particulate soil and iron humic acid stains when compared with example 2 of identical system but having pH 6.0, indicating more cleaning efficiency in the selected range. Additionally example 3 is also showing superior effect over the conventional detergent composition of example 1 having identical alkaline pH 10.5.
1. A cleaning composition comprising an immiscible liquid system having at least one liquid-liquid interface with an interfacial tension greater than 5 mN/m, characterised in that the composition has a pH ranging from above 7 to 12.
2. A composition as claimed in claim 1, wherein the less polar solvent of the system has a carbon chain length of at least 4.
3. A composition as claimed in claim 2, wherein the less polar solvent of the system has a carbon chain length, greater than 6.
4. A composition as claimed in claims 1-3, wherein the interfacial tension is greater than 10 mN/m.
5. A composition as claimed in claim 4, wherein the interfacial tension is greater than 20mN/m.
6. A composition as claimed in claim 1, wherein the less polar solvent of the system is a silicone with more than 3 SiO units.
7. A composition as claimed in claim 6, wherein the silicone is a polydimethylsiloxane.
8. A composition as claimed in claims 1-7, wherein the more polar solvent of the system is water.
9. A composition as claimed in claim 1, wherein the less polar solvent of the
system is perchlorethylene.
10.A process for cleaning soiled fabric comprising treating the soiled fabric with a composition as claimed in claims 1-9.
Dated 10th October 2002.
Of S. Majumdar and Co.
|Indian Patent Application Number||1001/MUM/2001|
|PG Journal Number||13/2008|
|Date of Filing||12-Oct-2001|
|Name of Patentee||HINDUSTAN UNILEVER LIMITED|
|Applicant Address||HINDUSTAN LEVER HOUSE , 165/166 BACKBAY RECLAMATION, MUMBAI-400 020,|
|PCT International Classification Number||C04B14/00|
|PCT International Application Number||N/A|
|PCT International Filing date|