EP2031050A1

EP2031050A1 - A process for cleaning fabrics

Info

Publication number: EP2031050A1
Application number: EP07120469A
Authority: EP
Inventors: Shubhadeep Banerjee; Kaushik Bose; Deeleep Kumar Rout; Ritesh Kumar Sinha
Original assignee: Unilever NV
Current assignee: Unilever NV
Priority date: 2007-08-29
Filing date: 2007-11-12
Publication date: 2009-03-04

Abstract

The present invention provides a process for cleaning a fabric including the step of contacting the fabric with two components sequentially, in any order, wherein;
a. the first component includes an organic acid with molecular weight greater than 200 and having at least two carboxylic acid groups, and;

the second component includes an alkaline material.

Description

Technical Field

The invention relates to a process for cleaning fabrics. It particularly relates to a multi-step process for cleaning fabrics.

Background and Prior Art

Conventional process of cleaning fabrics is typically a single step process of contacting a fabric with a detergent formulation in presence of water. Typically, this process involves soaking fabrics in a soak solution of commercially available detergent formulations in water, followed by washing, and then followed by rinsing to get rid of excess water, dirt and leftover surfactant. The steps of washing and rinsing are usually aided by means of agitation, provided either manually as in hand-wash or mechanically as in machine wash. In conventional processes, cleaning performance deteriorates with increase in water hardness, or with decrease in wash temperature. Conventional processes also require longer time and consumption of high quantity of water.
Alternate processes of cleaning fabrics in which the fabric is treated sequentially with at least two cleaning components are also known in the art.
GB338121 (1930 ) describes a process of washing by adding together or one after another two components to the wash where the first component comprises saponifiable fatty acids such as oleic acid, palmitic acid, or stearic acid and the second component comprises alkaline saponifying agents such as sodium carbonate, sodium bicarbonate or sodium hydroxide.
The above process involves fatty acids which are not readily soluble in water and solvents are used to solubilize fatty acids to facilitate their uniform application to fabrics. Other approach is use of an emulsifying agent for forming an aqueous emulsion to facilitate uniform application of fatty acids to fabrics.
FR1460904 (1966 ) describes a process of washing fabrics in which aqueous emulsion of saponifiable fatty acids is combined with the alkaline wash solution. Fatty acids are preferably selected from oleic acid or low-melting fatty acid mixture and emulsifying agent is a low HLB nonionic surfactant.
GB333177 (1930 ) describes a process of washing consisting of successively treating the material to be washed with a dilute emulsion of saponifiable fatty acids and with a dilute alkali to generate soap in-situ.
GB501422 (1939 ) describes a process for washing articles with a fatty acid component and an alkali component where the aqueous fatty acid emulsion comprises methyl cyclohexanol.
The cleaning using the two-step processes described above which involve fatty acid is relatively less efficacious. Further, it is difficult to uniformly apply water-insoluble fatty acid on fabric unless it is dissolved in a solvent or emulsified using an emulsifying agent.
Therefore, another approach is to use water-soluble organic acids instead of fatty acids in a two-step wash process.
GB2315762 (Procter and Gamble, 1998) describes a detergent composition comprising a detergent surfactant, a dicarboxylic acid source and an alkaline source. Dicarboxylic acid source is selected from fumaric acid, malic acid, maleic acid, tartaric acid, malonic acid, or a salt or ester thereof.
EP11767501 (Procter and Gamble, 2002) describes a process of washing a fabric by successively treating the fabric, in any order, with a first component and a second component which are capable of generating heat upon contact. The components are selected such that contact of the components is a part of an exothermic process of either a physical or a chemical nature and results in generation of heat. A list of exothermic processes is given and includes dissolution of organic/inorganic salts, oxidation/reduction, hydration of substantially anhydrous compounds and acid/base reactions. In acid-base reactions, the acids, whether organic or inorganic, are preferably strong acids with pKa less than 4, or more preferably less than 2. Preferred organic acids include choloro acetic acid, dichloro acetic acid, acetic acid, oxalic acid, formic acid, lactic acid or mixtures thereof.
The use of strong acids which are water soluble helps in eliminating problems related to use of insoluble fatty acids as there is no need to use solvents or emulsifying agents. However, strong acids are difficult to handle, store and keep out of reach of minors. For consumers who prefer hand-wash, it is particularly problematic to handle strong acids and keep them out of reach of children. Further, packaging of strong acids is another issue which may lead to leaking or may require expensive packaging materials. In context of washing machines, strong acids such as mineral acids may not be compatible with the material of construction of washing machines. Strong acids may also cause damage to expensive and delicate fabrics or textile accessories like buttons and elastic.
In view of the problems associated with prior art described above, one of the objectives of the present invention is to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
Another object of the present invention is to provide a process for cleaning fabrics which causes relatively less damage to fabrics.
Yet another object of the present invention is to provide a process for cleaning fabrics which can be used to effectively remove particulate soils.
Yet another object of the present invention is to provide a process for cleaning fabrics which may be carried out in absence of conventional surfactants.
Present inventors have surprisingly found that a two-step cleaning process involving successive treatment of fabric with specific organic acids and an alkali provides good cleaning and yet causes relatively less damage to fabrics.

Summary of the invention

According to the present invention there is provided a process for cleaning a fabric including the step of contacting the fabric with two components sequentially, in any order, wherein;

a. the first component includes an organic acid with molecular weight greater than 200 and having at least two carboxylic acid groups, and;
b. the second component includes an alkali.

Preferably the pKa of the acid is greater than 4.

Detailed description of the invention

The first component

The first component includes an organic acid that has a molecular weight greater than 200, and has at least two carboxylic acid groups.
The organic acid is 0.01-100%, preferably 0.01-10%, more preferably 0.1-5% by weight of the first component.
The pKa of the acid is preferably greater than 4, more preferably greater than 4.1 and most preferably greater than 4.5.
The molecular weight of the organic acid is preferably greater than 200, more preferably greater than 300, and most preferably greater than 1000. According to a preferred aspect, molecular weight of organic acid is preferably from 200 to 5000000, more preferably from 300 to 4000000, most preferably from 1000 to 1000000.
Preferably, the acid is selected from a polycarboxylic acid or an oligomer of C12-C30 unsaturated fatty acid.
Polycarboxylic acid is particularly preferred. polycarboxylic acid has preferably greater than three, more preferably greater than 10, most preferably greater than 25 carboxylic acid groups. Preferred polycarboxylic acids include polyacrylic acid, polymethacrylic acid, polymaleic acid, polyacrylic/polymaleic acid co-polymers, and poly amino acid. Non-limiting examples of poly amino acids include poly gamma glutamic acid and polyaspartic acid. Polyacrylic acid is particularly preferred.
According to another aspect, organic acid is an oligomer of C12-C30 unsaturated fatty acid. The term unsaturated fatty acid as used herein means a fatty acid with at least on carbon-carbon double bond. The term oligomer as used herein refers to a polymer comprising two to five monomer units. A dimer of an unsaturated fatty acid is particularly preferred in the process of the present invention.
The organic acid can be water-insoluble or water-soluble. Examples of preferred water-insoluble acids include dimer of C12-C30 unsaturated fatty acid. When the organic acid is water-insoluble, the first component comprises 0-99.99%, preferably 90-99.99%, more preferably 95-99.99% non-aqueous carrier. The non-aqueous carrier preferably comprises solvents capable of dissolving the water-insoluble organic acid. Commonly used organic non-chlorinated and chlorinated solvents can be used. Some non-limiting examples of solvents that can be used according to the present invention include methanol, acetone, chloroform, and dichloromethane. Alternatively, water-insoluble acid may be emulsified in an aqueous medium using an emulsifying agent.
According to a preferred aspect, organic acid is water-soluble. When the organic acid is water-soluble, the first component comprises 0-99.99%, preferably 90-99.99%, more preferably 95-99.99% aqueous carrier. The aqueous carrier preferably comprises water. The aqueous carrier may further comprise conventional detergent ingredients. It is preferred that the conventional detergent ingredients included in the aqueous carrier of the first component are not alkaline. Some examples of ingredients that can be added with the first component include optical brighteners (e.g., Tinopal® CBSX/Photine®)), electrolytes (e.g., sodium chloride, sodium sulphate, sodium citrate), perfume, and soil release polymers (e.g. sodium carboxymethyl cellulose and Gerol), acid-compatible phosphonic acid builders (methylenephosphonic acid, phosphonobutane tricarboxylic acid).
The first component may be a solid, liquid, paste, gel or any other suitable format. Preferably, the first component is liquid.

The second component

The second component includes an alkaline material. The alkaline material according to the present invention includes any material that has an alkaline pH when mixed with water. When mixed with water, the alkaline material has a pH of greater than 7.5, preferably greater than 8.5, more preferably greater than 9 and most preferably greater than 10.
Alkaline material can be inorganic or organic. Preferably, the alkaline material is inorganic. Preferably, inorganic alkaline material is selected from carbonate, bicarbonate, phosphate or hydroxide of an alkali metal, alkaline earth metal or ammonium. Particularly preferred inorganic alkaline material is selected from carbonate, bicarbonate, phosphate or hydroxide of an alkali metal. Amongst alkali metals, sodium is particularly preferred. The most preferred alkaline material is selected from sodium carbonate, sodium tripolyphosphate or mixture thereof.
According to another aspect, alkaline material is selected from organic bases. Some non-limiting examples of organic bases include C1-C10 amines, C1-C10 alkanolamines and urea.
The alkaline material is 0.1-100%, preferably 0.1-20%, more preferably 0.1-5% by weight of the second component.
The second component includes 0-99.9%, preferably 80-99.9%, more preferably 95-99.9% by weight an aqueous carrier. The aqueous carrier preferably comprises water. The aqueous carrier may further comprise of conventional detergent ingredients. It is preferred that the conventional detergent ingredients included in the aqueous carrier of the second component are not acidic.
Conventional detergent ingredients that can be included in the aqueous carrier of the second component include zeolite, co-builders such as CP5, phosphonates such as salts of phosphonobutane tricarboxylic acids, and reductive bleaches such as sodium sulphite.
The second component may be used in a solid, liquid, paste, gel or any other suitable format. According to one of the preferred aspect the second component is used in the solid form.

Conventional surfactants

Either of the components may include a surfactant conventionally used in the detergent formulations. The surfactant can be anionic, non-ionic, cationic or mixture thereof. Anionic surfactants can include soaps as well as non-soap detergents.
According to an alternate and referred aspect, each of the components, i.e. the first and the second component, are substantially free of surfactant.

Optional ingredients

Conventional detergent formulations comprise several ingredients for specific functions. Such ingredients include fluorescer, soil-release polymer, builder, bleach, and optical bleach, brightener, and particulate fillers. It is envisaged by the present inventors that one or both the components comprise ingredients used in conventional detergent formulations. It is preferred however that the first component does not comprise alkaline ingredients and the second component does not comprise acidic ingredients.

Packaging of the two components

It is envisaged that the two components are packaged in a variety of ways so as to make it convenient for the consumer. Accordingly, both the components may be individually packaged. Alternatively, both the components can be packaged in a two-compartment packaging such that the two components are separated from each other by a barrier material.
When both the components are in liquid form, they can be preferably packaged in a two-compartment bottle or pouch such that the two components are separated from each other by a barrier material. Preferably, the packaging has individual dispensing means to allow dispensing of each of the component separately. According to a preferred aspect, the dispensing means include spraying means for convenient local application on specific area of fabric.
When any of the components is in particulate solid form, it can be packaged in a sachet. In a preferred aspect, the sachet is for single dosage. Alternately, any of the components, when in solid form, can be in form of a shaped solid such as a bar or stick. The bar or stick form may be conveniently used for local application to fabrics.

Format of use of the process

The process of the present invention can be conveniently used as a hand-wash process, as it causes relatively less damage to hands as compared to the prior art methods.
Alternatively, the process can be used in the washing machines.
It is envisaged that the process of the present invention can be practiced in many forms.
According to one aspect, the fabric is first soaked in a container containing first component, removed from the container, and dipped into the second component. Alternatively, the fabric is first soaked in a container containing the second component, removed from the container, and dipped into the first component.
According to one of the aspects, the fabric is soaked in the first component comprising an organic acid and aqueous carrier, and then washed with detergent powder comprising an alkaline material. Preferably, the first component is sprayed on or contacted with a localized stain and then washed with a detergent powder or bar comprising an alkaline material. According to this aspect, the method can be used for pre-treatment of localized stains.
According to another aspect, the fabric is sprayed with one of the components and then dipped or soaked in the other component.
It is one of the preferred aspects of the invention that the ratio of weight of the component that is contacted with the fabric later, to the weight of the component that is contacted with the fabric earlier, is greater than 1, preferably greater than 5, more preferably greater than 10 and most preferably greater than 20.
According to yet another preferred aspect, the process of cleaning is carried out in a washing machine capable of sequentially releasing the two components.

Order of contact

The fabric is contacted with the first component and the second component, in any order. Fabric may be contacted with the first component and followed by contacting with the second component. Alternatively, the fabric may be contacted with the second component, and followed by contacting with the first component.
When the fabric is contacted with the second component after the first component, the alkalinity of the second component causes slimy or slippery feel resulting into usage of larger amounts of water during rinsing. It is preferred that the fabric is contacted with the second component before contacting with the first component. The preferred order of contact provides an advantage of usage of relatively less water for rinsing, and also results into perception of better sensory and less damage to hands; particularly in a hand-washing process.
The term "liquor to cloth ratio" (or L/C ratio) as used herein means the ratio of mass of liquid to the mass of fabric in contact with the liquid.
The liquor to cloth ratio can be anywhere from 1 to 150, during the step of contacting with any one of the components that includes aqueous carrier. The liquor to cloth ratio during contact with any one of the components is preferably less than 20, more preferably less than 10 and most preferably less than 5. When the liquor to cloth ratio from about 2 to about 4 is used in each step of the process, superior cleaning is obtained with relatively less usage of water

Advantages of the process

The process according to the present invention has some advantages over the processes of the prior art.
The process of the present invention can be carried out at a temperature between 0-90 °C, preferably between 5-60 °C, more preferably between 10-50 °C. It is one of the advantages of the present invention that superior cleaning is obtained even at relatively low wash temperature.
The process of the present invention can be carried out in soft water as well as hard water. It is one of the advantages of the present invention that superior cleaning is obtained with water that has relatively high water hardness.
The process of the present invention can be used for removing spots or stains from a localized area of a fabric.
The process for cleaning fabrics according to the present invention is particularly suitable for cleaning delicate garments or accessories such as buttons, lace and elastic as it causes relatively less damage.

Examples

The invention will be now illustrated with non-limiting examples. The examples are by way of illustration only and do not limit the scope of the invention in any manner.

Materials and methods

Details of the materials used are given in Table 1.

Table 1: Materials used

Material	Source	Form used
Test fabric WFK10A	WFK, Germany	10 cm by 10 cm swatch
Test fabric WFK10D	WFK, Germany	10 cm by 10 cm swatch
Particulate soil test monitor	Prepared from desized cotton/ WFK10A by method described below.	10 cm by 10 cm swatch
Surf Excel® Quickwash detergent powder	INDIA	1.5 to 18 g/L in water
Rin Advanced® detergent powder	INDIA	3 to 4.5 g/L in water
Polyacrylic acid molecular weight 1800-40,000,00	Sigma-Aldrich, India	0.1-20 g/L in water
Water	Deionized water, unless specified otherwise
Hard Water		24 and 48 °FH (French Hardness) water prepared by dissolving CaCl₂ and MgCl₂ (2:1) in DI water
Hydrochloric acid	Merck	0.0001 N
sodium carbonate	Merck	0.1-5 g/L in water
Sodium tripolyphosphate	Rolex Chem Industries, India	0-3 g/L in water,
Conventional detergent powder	Composition given below	1.5-18 g/L

Composition of conventional detergent powder used in \the examples

Linear alkylbenzene sulfonic acid - sodium salt 24%, fatty alcohol 7 ethoxylate 1%, sodium tripolyphosphate 35.4%, sodium carbonate 28.1%, sodium carboxymethyl cellulose (SCMC) 1.6% poly(sodium acrylate-co-maleate (CP5®) 0.5%, High surface area calcite (FORCAL-U®) 2.1%, sodium sulphite 3.1%, water - balance

Protocol of preparing particulate soil test monitors

Particulate soil composition: China clay 90%, silica 5%, carbon soot (collected from diesel engine fumes) 2.5% and iron oxide 2.5%
5 g of the above soil was taken in 500 mL of deionized water and stirred in a Silverson® mixer at 6000 rpm for 15 minutes and then sonicated for 90 minutes. Volume of the suspension was taken such that it was sufficient to submerge the sonicator probe. Fabric test monitors (10 cm 10 cm swatch of WFK 10A or desized cotton) were slowly dipped into the suspension (suspension was continuously stirred with a glass rod). After removing from the suspension, the fabrics were placed on a clean board and rolled with a clean glass rod to uniformly distribute the soil. The fabrics were then dried and used.

Cleaning Protocols

The soiled fabric swatches (10 cm x 10 cm) were first treated with the first component comprising organic acid, followed by contacting with the second component comprising alkaline material. Experiments were also carried out where order of contacting was reversed, i.e. the second component was contacted with fabric and the wetted fabric was then contacted with the first component. All experiments were carried out with 5 fabric swatches and the results reported are for 5 replicates, unless specified otherwise.
When the acid used was water soluble, the first component was in form of aqueous solution. Water insoluble acids were dissolved in chloroform. The first component was contacted with the fabric swatch by pipetting the solution on to fabric (2 mL per swatch). The wetted fabrics were then soaked in the second component (in form of aqueous solution of alkali). Sodium carbonate, sodium tripolyphosphate and mixtures thereof were used as alkali (0.1-3 g/L sodium carbonate and 0.1 - 3 g/L sodium tripolyphosphate). The soaking in the second component was for a time period of 30 minutes directly in the washing pot of tergetometer (Instrument marketing services Inc., Fairfield, NJ 07004) or launderometer (Linitest) without agitation. Soaking time of 30 minutes was used in the experiments, unless specified otherwise. Wash liquor to cloth ratio (by weight) was maintained at 50 in the tergetometer. In launderometer, the wash liquor to cloth ratio (by weight) was varied from 10 to 50. The wash time duration was 15 minutes. The agitation in the tergetometer was provided by a vertical spindle rotating at an angular speed of 75 RPM and in the launderometer by a tumbling mechanism at a speed of 45 RPM. In launderometer, nine steel balls of about 4 mm diameter were added in each launderometer pot for providing additional agitation to fabric during tumbling action. The washing was followed by two rinses of 2 minutes each. The washed clothes were dried in a tumble drier (IFB make) for 15-30 minutes.
All experiments were carried out with deionized water (0 °FH) and at a temperature of 25 °C, unless specified otherwise.

Measurement of cleaning efficacy

Reflectance of fabrics was measured as an indicator of cleaning efficacy. Reflectance measurements, at 460 nm wavelength, before and after wash were carried out with the help of Gretag Macbeth reflectometer (Color Eye 7000A). The UV component of the incident light was blocked by appropriate filter devices, built in the system, in order to avoid any possible artifacts on account of fluorescence emitted by fluorescer molecules if present on fabric. Measurements of reflectance are based on 5 swatches, and expressed as: mean ± standard deviation.

Measurement of assessing damage to fabrics

Breaking strength of fibers was used as a measure of damage to fabrics. Texture analyzer (Instron Series IX) (TA Instruments, TA-HDi) was used for measurement of strength of fibers. Individual fibers were drawn out from the washed fabrics. A single fiber was attached to the fixture meant for tensile strength measurement and axial tension was applied. A 5 kg load cell was used for the experiment. Care was taken so that the fiber was stretched between the load cell and the bottom fixture prior to the application of axial tension. The load cell was pulled upward at a rate of 1 mm/s till the fiber withstood the applied tension. When the applied tension exceeded that of the tensile strength of the fiber, the fiber snapped and the corresponding tension at the break was noted.

Effect of pKa of acid

Experiments were carried out as reported in the procedure, under following conditions.

Apparatus :	Tergetometer
Fabric used :	Particulate soil test monitor (cotton)
Volume of first component :	10 mL
Second Component :	0.3 g/L sodium carbonate + 0.2 g/L sodium tripolyphosphate
Volume of second component :	400 mL
Soaking time :	30 minutes
Order of contact :	first component followed by second component

Following table gives the effect of type of acid used (mineral acid vs. polyacrylic acid) as the first component and corresponding cleaning results obtained. Example 1 is within the scope of the present invention whilst the comparative example 1-A is outside the scope of the present invention. Table 2: Effect of type of acid used on cleaning efficacy

Example no First Component Cleaning Efficacy (ΔR460*)

1 Polyacrylic acid, molecular weight 1800, 2.8 g/L, pKa = 4.8, 17 ± 0.4

1-A Hydrochloric acid 0.05 N (pKa < 4) 14 ± 0.5
It is clear from the results that cleaning efficacy of acid used in the present invention is better than that of an acid used in the prior art.
Further, the breaking strength was measured for fibers cleaned using the process of example 1 and the comparative example 1-A. The results are given in Table 3. Table 3: Effect of type of acid used on damage

Example No. Breaking strength of fiber (N/m)

1 123 ± 12

1-A 90 ± 14
It is clear from the table that the breaking tensile strength of the fiber is lower for the fabrics washed with mineral acid (hydrochloric acid) and alkali system of the prior art, in comparison with the fabrics washed by the process of the present invention. The result indicates that the process of the present invention causes relatively less damage to the fabrics as compared to the prior art processes, whilst providing improved cleaning benefits.

Effect of number of carboxylic acid groups

Following table gives the type of acid used in the first component and cleaning results obtained. Example 2 is within the scope of the present invention and comparative example 2-A is outside the scope of the present invention.

Table 4: Effect of number of carboxylic acid groups

Example no	First Component	Cleaning Efficacy (Δ*R460)**
2	16 g/L dimer acid(Dilinoleic acid) in chloroform, molecular weight = 556, Number of carboxylic acid groups per mole = 2	20.1±0.4
2-A	16 g/L fatty acid mixture (lauric:oleic acid:isostearic = 1:1:0.5 by wt.) in chloroform, average molecular weight = 251, no of carboxylic acid groups per mole = 1	16.9±0.4

It is clear from the results that cleaning efficacy of fatty acid dimmer comprising two carboxylic acid groups is better than that of a fatty acid used in the prior art.

Effect of order of addition of the components

Apparatus :	Tergetometer
Fabric used :	Particulate soil test monitor (cotton)
First component :	Polyacrylic acid, molecular weight 1800, 0.0027 g dissolved in water (volume given in Table 5)
Second Component :	0.12 g sodium carbonate + 0.08 g sodium tripolyphosphate in water (volume given in Table 5)
Soaking time in the component contacted later:	30 min

Following table gives the effect of various sequences of addition of the two components

Table 5: Effect of order of addition

Example no	Order of contact of components with fabric	Cleaning Efficacy (Δ*R460)**
3	First component (10 mL) followed by second component (400 mL)	16±0.4
4	Second component (10 mL) followed by first component (400 mL)	17±1
5	Fist component (10 mL) followed by second component (10 mL), followed by addition of 390 mL water	18±1
3-A	First component (10 mL) contacted with second component (400 mL) in a container, followed by immersion of fabric in the container	11.1±0.6

Examples 3, 4, and 5 are within the scope of the invention and example 3-A is outside the scope of the invention.
It is clear from the results that better cleaning efficacy is obtained regardless of order of contact of components with fabric using the multi-step process of the present invention as compared with the conventional cleaning process.

Cleaning efficacy at low wash temperature

Experiments were carried out as reported in the procedure, with the wash temperature maintained at about 5 °C.

Apparatus :	Tergetometer
Fabric used :	WFK 10A particulate soil test monitor in Examples 6, 6-A and 6-B, WFK 10D in examples 7, 7-A and 7-B
First component :	Polyacrylic acid, molecular weight 1800; 2.7 g/L solution
Volume of first component :	10 mL
Second Component :	0.8 g/L sodium carbonate + 1.0 g/L sodium tripolyphosphate
Volume of second component :	400 mL
Soaking time :	30 min

Following table gives the cleaning efficacy at low temperature. Example 6 is within the scope of the invention whilst comparative examples 6-A and 6-B are examples of conventional method of cleaning using commercially available detergent powders. The amount of first and second components used in example 6 and the amount of commercially available detergent powders used in examples 6-A and 6-B are chosen so that the cost of washing is identical. Examples 7, 7-A and 7-B are similar to corresponding examples 6, 6-A and 6-B, respectively except that the fabric used is WFK10D.

Table 6: Cleaning efficacy at low wash temperature (about 5 °C)

Example	Cleaning method	Cleaning Efficacy (Δ*R460)**
6	Similar to example 3	18.3 ± 0.8
6-A	Surf Excel® quickwash detergent powder, 3 g/L, L/C = 50	16.8 ± 1.2
6-B	Rin Advanced® detergent powder 4.5 g/L, L/C = 50	13.8 ± 1.1
7	Similar to example 3	18.6 ± 0.9
7-A	Surf Excel® quickwash detergent powder, 3 g/L, L/C = 50	16.2 ± 1.5
7-B	Rin Advanced Powder 4.5 g/L, L/C = 50	11.2 ±1

It is clear from the result that the cleaning process of the invention gives a better cleaning efficacy at low temperature as compared to conventional cleaning methods for same cost per wash.

Effect of water hardness on cleaning efficacy

Experiments were carried out as reported in the procedure.

Apparatus :	Tergetometer
Fabric used :	Particulate soil test monitor (cotton)
First component :	Polyacrylic acid, molecular weight 1800, 2.7 g/L solution
Volume of first component:	10 mL
Second Component :	0.8 g/L sodium carbonate + 1.0 g/L sodium tripolyphosphate
Volume of second component :	400 mL
Soaking time :	30 min

Table 7: Effect of water hardness

Example	Cleaning method	Water hardness (FH)	*Cleaning Efficacy (ΔR460)**
8	Similar to example 3	0	21 ± 0.3
8-A	Conventional detergent powder*, 3 g/L, L/C = 50	0	16.8 ± 0.6
9	Similar to example 3	24	16.6 ± 0.4
9-A	Similar to example 8-A	24	11 ± 0.4
10	Similar to example 3	48	13.4 ± 0.3
10-A	Similar to example 8-A	48	9.4 ± 0.4

From the results, it is clear although the cleaning efficacy reduces with the increase in water hardness, the cleaning efficacy of the process of the present invention is better than that of conventional cleaning processes in hard water.

Effect of soaking time

Experiments were carried out as reported in the procedure, except that the soaking time was 0 instead of 30 minutes

Apparatus :	Launderometer
Fabric used :	Particulate soil test monitor (cotton)
First component :	Polyacrylic acid, molecular weight 1800, 2.7 g/L solution
Volume of first component :	10 mL
Second Component :	0.8 g/L sodium carbonate + 1.0 g/L sodium tripolyphosphate (volume = 400 mL)
Volume of second component :	400 mL
Soaking time :	0 min

Table 8: Effect of eliminating soaking time

Example	Cleaning method	Cleaning Efficacy (Δ*R460)**
11	Similar to example 3	18.8 ± 0.8
11-A	Conventional detergent powder, 3 g/L, L/C = 50	15.2 ± 0.3

From the results, it is apparent that the cleaning efficacy of the process of the invention is better than that of the conventional washing process even when soaking time is eliminated.

Additional examples of acids and alkalis

Following additional examples of the first and the second component are given below.
Experiments were carried out as reported in the procedure.

Apparatus :	Tergetometer
Fabric used :	WFK10D in Examples 12-19 and 19-A, Particulate soil test monitor (WFK10A) in Examples 20-25 and 25-A
First component :	Polyacrylic acid, 2.7 g/L in all examples except Example 25 in which the concentration is 14 g/L, molecular weight given in Table 9 for each Example
Volume of first component :	10 mL
Second Component :	sodium carbonate + sodium tripolyphosphate (STPP), concentrations given Table 9.
Volume of second component :	400 mL
Soaking time :	30 min

Table 9: Examples of acids and alkalis

In all examples PAA stands for Polyacrylic acid.

Ex No	Mol. Wt. of polyacrylic acid ( )	Second Component (concentration in g/L)	Cleaning Efficacy (Δ*P460 )**
12	1800	0.8 g/L sodium carbonate + 1 g/L sodium tripolyphosphate	19 ± 0.2
13	2000	0.8 g/L sodium carbonate + 1 g/L sodium tripolyphosphate	19 ± 0.2
14	450000	0.8 g/L sodium carbonate + 1 g/L sodium tripolyphosphate	20 ± 0.2
15	4000000	0.8 g/L sodium carbonate + 1 g/L sodium tripolyphosphate	20 ± 0.29
16	1800	0.65 g/L MgCO₃ +1 g/L sodium tripolyphosphate	18.3 ± 2
17	1800	sodium tripolyphosphate 1 g/L	21.0 ± 0.9
18	1800	sodium tripolyphosphate 2.5 g/L	22.6 ± 1.0
19	1800	sodium tripolyphosphate 4 g/L	22.0 ± 1.0
19-A	-* *	-* *	13 ± 0.2
20	1800	sodium tripolyphosphate 2.5 g/L	19.0±0.5
21	1800	sodium tripolyphosphate 1 g/L	20.0 ± 1
22	1800	sodium tripolyphosphate 4 g/L	20.0 ± 0.5
23	1800	0.82 g/L Sodium carbonate, 0.2 g/L sodium tripolyphosphate	19 ± 1.6
24	1800	0.3 g/L Sodium carbonate, 0. 2 g/L sodium tripolyphosphate	19.8± 0.8
25	1800	0.8 g/L sodium carbonate, 1 g/L sodium tripolyphosphate	20.1 ± 0.5
25-A	-**	-**	14 ± 0.2

** Cleaning with conventional detergent, 3 g/L, L/C= 50.

Examples 12-15 demonstrate the range of molecular weights of polycarboxylic acid that can be used in the process of the present invention. It is also seen that the cleaning efficacy improves with the increase in molecular weight of acid used. Examples 16-19 demonstrate the types of alkalis and concentrations thereof that can be used according to the present invention. Example 19-A, which is a conventional cleaning method, is outside the scope of the present invention and is a comparative example for examples 12-19. Examples 20-25 are further examples according to the present invention which demonstrate superior cleaning over comparative example 25-A.
It will be appreciated that the illustrated examples demonstrate that the process of the present invention allows relatively better cleaning, particularly of particulate soils, with relatively less damage to fabrics without using conventional surfactants.

Claims

A process for cleaning a fabric including the step of contacting the fabric with two components sequentially, in any order, wherein;
a. the first component includes an organic acid with molecular weight greater than 200 and having at least two carboxylic acid groups, and;

b. the second component includes an alkaline material.
A process as claimed in claim 1 wherein pKa of said acid is greater than 4.
A process as claimed in claim 1 or claim 2 wherein said acid is selected from a polycarboxylic acid or an oligomer of C12-C30 unsaturated fatty acid.
A process as claimed in claim 3 wherein said acid is polycarboxylic acid.
A process as claimed in claim 4 wherein said acid is polyacrylic acid.
A process as claimed in any one of the preceding claims wherein said molecular weight is from 200 to 5,000,000.
A process as claimed in claim 6 wherein said molecular weight is from 1000 to 1,000,000.
A process as claimed in any one of the preceding claims wherein said alkaline material is organic or inorganic.
A process as claimed in claim 8 wherein said alkaline material is inorganic.
A process as claimed in claim 9 wherein said alkaline material is selected from carbonate, bicarbonate, phosphate or hydroxide of an alkali metal.
A process as claimed in claim 10 wherein said alkaline material is selected from sodium carbonate, sodium, tripolyphosphate or mixture thereof.
A process as claimed in any one of the preceding claims wherein said acid is 0.01-100% by weight of the first component.
A process as claimed in any one of the preceding claims wherein said alkaline material is 0.01-100% by weight of the second component.
A process as claimed in any one of the preceding claims wherein each of the components is substantially free of surfactant.
A process as claimed in any one of the preceding claims wherein fabric is contacted with the second component before contacting with the first component.