WO2024250137A1

WO2024250137A1 - Method for evaluating efficacy of detergent composition for preventing formation of secondhand stain on fabrics

Info

Publication number: WO2024250137A1
Application number: PCT/CN2023/098276
Authority: WO
Inventors: Xiaoyi Ren; Ming Tang; Renae Dianna Fossum; Ye Tian; Jiemin SHEN; Yanli Zhang; Di YUAN; Xiaobin CHU
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2023-06-05
Filing date: 2023-06-05
Publication date: 2024-12-12
Anticipated expiration: 2025-12-05
Also published as: CN119125514A

Abstract

A method of evaluating the efficacy of a detergent composition for preventing formation of a secondhand stain (also called "cross-contamination stain" ) on fabrics is provided.

Description

METHOD FOR EVALUATING EFFICACY OF DETERGENT COMPOSITION FOR PREVENTING FORMATION OF SECONDHAND STAIN ON FABRICS

FIELD OF THE INVENTION

The present invention relates to a method of evaluating the efficacy of a detergent composition for preventing formation of a secondhand stain (also called “cross-contamination stain” ) on fabrics.

BACKGROUND OF THE INVENTION

As detergent products are evolving, consumer needs in terms of cleaning have been well met. However, there are still some other unmet consumer needs in the field of laundry. Particularly, one of the unsolved issues is that most clothes become grayer/darker and less colorful after a period of usage when washed multiple times. Even though clothes look clean after washing, they do not look as new and colorful as the original ones. In other words, clothes look “old” as time passes.

The reasons that underly the issue as mentioned above are quite complex. Previous research was conducted to understand the mechanism behind such issue. For example, the phenomenon of soil redeposition was identified as one of the reasons resulting in the above issue and a number of actives including soil redeposition polymer (SRP) have been developed to mitigate the above issue. However, the efficacy of such SRP is not satisfied by consumers. Therefore, there is a need for understanding more about this issue and developing additional approaches to solve the above-mentioned issue.

SUMMARY OF THE INVENTION

The present inventors surprisingly identified that one of important reasons for the above-mentioned issue is that the clothes were contaminated by a mix of stain sources during the washing process, especially during mixed washing. The present inventors name the stains formed by such mix of stain sources during wash as a secondhand stain (also called “across-contamination stain” ) . Similarly as secondhand smoke, so-called secondhand stain refers to a stain caused by a passive process, i.e. the washing of the fabric, but not an active process, i.e., common usage. Particularly, the present inventors discovered that the secondhand stain is formed by a mixture of clay soil and body soil as well as optionally a dye (also called “asecondhand soil” ) during the mixed washing loads of clothes. In mixed washing, clothes of male and females, outer clothes and inter clothes, and clothes having a light color and a dark color are mixed. In this case, different stain sources e.g. clay soil including particles of SiO2 and/or metal oxides, body soil including lipids and proteins as well as dyes are present together in the washing liquor. Different from a simple soil redeposition, clay soil and body soil as well as optionally a dye in the mixed washing can constitute a complex washing liquor in which these ingredients may interact with each other. Such washing liquor containing the secondhand soil may comprise smaller particles (e.g. sub-micron and/or nano-scale particle size) that can penetrate deeply into the interstices of the fabric or yarn or even located deeply in internal pores of fibre. They cannot be easily seen by consumers and also by analytical devices, but they may contribute to the issue that clothes turn grey and/or dull after washing.

Based on the surprising discovery as mentioned above, the present inventors have developed a method of evaluating the efficacy of a detergent composition for preventing formation of a secondhand stain on fabrics, the method comprising the steps of: A) providing a secondhand soil composition, a fabric, and the detergent composition to be evaluated; B) adding the secondhand soil composition, the fabric and the detergent composition to be evaluated into water to form a washing liquor; C) washing the fabric in the washing liquor; and D) measuring Whiteness Maintenance Index of the fabric, wherein the secondhand soil composition comprises clay soil and body soil in which the weight ratio of the clay soil to the body soil is from 5: 1 to 1: 3.

In some embodiments according to the present application, the weight ratio of the clay soil to the body soil is from 4: 1 to 1: 3, preferably from 3: 1 to 1: 2.5, more preferably from 2: 1 to 1: 2.5, and most preferably from 1: 1 to 1: 2.5.

In some embodiments according to the present application, the secondhand soil composition further comprises a dye which is at a level of from 0.001 wt%to 1.5%, or from 0.01wt%to 1wt%, preferably from 0.03wt%to 0.5wt%, more preferably from 0.05wt%to 0.3wt%, by the total weight of the secondhand soil composition.

In some embodiments according to the present application, the secondhand soil composition is present in the washing liquor at a level of from 0.03g/L to 15g/L, preferably from 0.1g/L to 10g/L, more preferably from 0.3g/L to 5g/L, even more preferably from 0.5g/L to 2g/Lfor example 0.1g/L, 0.2g/L, 0.3g/L, 0.4g/L, 0.5g/L, 0.7g/L, 1g/L, 1.5g/L, 2g/L, 2.5g/L, 3g/L or any ranges therebetween.

In some embodiments according to the present application, in the washing liquor the clay soil is present at a level of from 0.05g/L to 12g/L, preferably from 0.2g/L to 5g/L, more preferably from 0.3g/L to 2g/L, for example 0.05g/L, 0.3g/L, 1.0g/L, 2.0g/L or any ranges therebetween.

In some embodiments according to the present application, in the washing liquor the body soil is present at a level of from 0.05g/L to 12g/L, preferably from 0.2g/L to 5g/L, more preferably from 0.3g/L to 2g/L, for example 0.05g/L, 0.3g/L, 1.0g/L, 2.0g/L or any ranges therebetween.

In some embodiments according to the present application, in the washing liquor the dye is present at a level of from 0.0005g/L to 1g/L, preferably from 0.001g/L to 0.5g/L, more preferably from 0.005g/L to 0.2g/L, for example 0.0001g/L, 0.0002g/L, 0.0005g/L, 0.001g/L, 0.002g/L, 0.003g/L, 0.004g/L, 0.01g/L, 0.02g/L, 0.03g/L, 0.04g/L, 0.05g/L, 0.1g/L, 0.2g/L or any ranges therebetween.

In some embodiments according to the present application, the clay soil has an average particle size of from 0.03μm to 50μm, preferably from 0.1μm to 30μm, more preferably from 0.2μm to 10μm, most preferably from 0.5μm to 5μm, for example 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or any ranges therebetween.

In some embodiments according to the present application, the detergent composition is determined as having the efficacy for preventing formation of secondhand stain when the Whiteness Maintenance Index of the fabric is from 0.1 to 8, preferably from 0.3 to 7, more preferably from 0.5 to 6.5, most preferably from 0.5 to 6, as measured in accordance with Test 1: Whiteness Maintenance Index Test for Secondhand Stain.

In some embodiments according to the present application, the fabric is selected from the group consisting of cotton, polycotton, regenerated cotton, synthetically modified cotton, linen, wool, polyester, nylon, elastane, silk, acrylic, and any combinations thereof, preferably the fabric is cotton, polycotton, regenerated cotton, synthetically modified cotton, polyester, nylon, elastane or any combinations thereof.

In some embodiments according to the present application, the detergent composition comprises a treatment adjunct which is preferably selected from the group consisting of a surfactant system, fatty acids and/or salts thereof, enzymes, encapsulated benefit agents, soil release polymers, hueing agents, builders, chelating agents, dye transfer inhibiting agents, dispersants, enzyme stabilizers, anti-oxidants, catalytic materials, bleaching agents, bleach catalysts, bleach activators, polymeric dispersing agents, soil removal/anti-redeposition agents, polymeric grease cleaning agents, amphiphilic copolymers, brighteners, suds suppressors, dyes, hueing agents, perfume, structure elasticizing agents, fabric softeners, carriers, fillers, hydrotropes, solvents, anti-microbial agents and/or preservatives, neutralizers and/or pH adjusting agents, processing aids, rheology modifiers and/or structurants, opacifiers, pearlescent agents, pigments, anti-corrosion and/or anti-tarnishing agents, and mixtures thereof.

In some embodiments according to the present application, the secondhand stain is a stain on fabrics which is formed during the washing of the fabric, preferably wherein the secondhand stain is a stain on fabric which is formed by a mixture of clay soil and body soil as well as optionally dye (s) during the washing of the fabric.

In some embodiments according to the present application, the Whiteness Maintenance Index of the fabric is determined by measuring L*AB and calculating ΔE as the Whiteness Maintenance Index, preferably wherein the Whiteness Maintenance Index of the fabric is determined in accordance with Test 1: Whiteness Maintenance Index Test for Secondhand Stain.

In another aspect, the present application is related to a method for preventing formation of secondhand stain on fabrics, the method comprising the steps of:

A) providing fabrics;

B) treating the fabrics with a detergent composition comprising from about 0.05%to about 15%, preferably from about 0.1%to about 5%, more preferably from about 0.2%to about 3%, by weight of the detergent composition, of a polyalkylene oxide graft copolymer comprising:

a) polyalkylene oxide component as a graft base in which the polyalkylene oxide has a number average molecular weight of from 1000 to 20,000 Daltons and is based on ethylene oxide, propylene oxide, butylene oxide or mixtures thereof,

b) polyvinyl ester component as side chains in which the polyvinyl ester is derived from a saturated monocarboxylic acid containing from 1 to 6 carbon atoms and/or a methyl or ethyl ester of acrylic or methacrylic acid, and

c) polyvinylpyrrolidone as side chains,

wherein the weight ratio of (a) : (c) is from 1: 0.1 to 1: 2, and

wherein the amount, by weight, of (a) is greater than the amount of (b) .

In another aspect, the present application is related to a method for laundering fabric, the method comprising the steps of:

A) providing mixed fabrics and a detergent composition;

B) adding the mixed fabrics and the detergent composition into water to form a washing liquor; and

C) washing the mixed fabrics in the washing liquor,

wherein the detergent composition comprises from about 0.05%to about 15%, preferably from about 0.1%to about 5%, more preferably from about 0.2%to about 3%, by weight of the detergent composition, of a polyalkylene oxide graft copolymer comprising:

c) polyvinylpyrrolidone as side chains,

wherein the weight ratio of (a) : (c) is from 1: 0.1 to 1: 2, and

wherein the amount, by weight, of (a) is greater than the amount of (b) .

In one embodiment according to the present application, the mixed fabrics refer to fabrics with different types of stains. Preferably, the mixed fabrics are selected from the group consisting of a mixture of clothes of male and females, a mixture of outer clothes and inter clothes, a mixture of clothes having a light color and a dark color, and any combinations thereof.

In one embodiment according to the present application, in the graft copolymer, a) the polyalkylene oxide comprises and preferably consists of ethylene oxide units or ethylene oxide and propylene oxide units, and b) the polyvinyl ester comprises and preferably consists of vinyl acetate.

In one embodiment according to the present application, in the graft copolymer, the polyalkylene oxide has a number average molecular weight of from 2000 to 15,000 Daltons; and/or, the weight ratio of (a) : (b) is from 1.0: 0.1 to 1.0: 0.99, preferably from 1.0: 0.3 to 1.0: 0.9; and/or, the polyalkylene oxide graft polymer has a weight average molecular weight of from 4,000 Da to 100,000 Da.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

As used herein, the articles including “a” and “an” when used in a claim, are understood to mean one or more of what is claimed or described.

As used herein, the terms “comprise” , “comprises” , “comprising” , “include” , “includes” , “including” , “contain” , “contains” , and “containing” are meant to be non-limiting, i.e., other steps and other ingredients which do not affect the end of result can be added. The above terms encompass the terms “consisting of” and “consisting essentially of” .

As used herein, when a composition is “substantially free” of a specific ingredient, it is meant that the composition comprises less than a trace amount, alternatively less than 0.1%, alternatively less than 0.01%, alternatively less than 0.001%, by weight of the composition, of the specific ingredient.

As used herein, the term “laundry detergent composition” means a composition for cleaning soiled materials, including fabrics. Such compositions may be used as a pre-laundering treatment, a post-laundering treatment, or may be added during the rinse or wash cycle of the laundering operation. The laundry detergent composition compositions may have a form selected from liquid, powder, unit dose such as single-compartment or multi-compartment unit dose, pouch, tablet, gel, paste, bar, or flake. Preferably, the laundry detergent composition is a liquid or a unit dose composition. The term of “liquid laundry detergent composition” herein refers to compositions that are in a form selected from the group consisting of pourable liquid, gel, cream, and combinations thereof. The liquid laundry detergent composition may be either aqueous or non-aqueous, and may be anisotropic, isotropic, or combinations thereof. The term of “unit dose laundry detergent composition” herein refers to a water-soluble pouch containing a certain volume of liquid wrapped with a water-soluble film.

As used herein, the term "secondhand stain" means a stain on fabrics which is not formed during the usage of the fabric, but during the washing of the fabric. Particularly, during washing process, various stain/soils/dyes are removed from fabric surface to washing liquor, and then become a complex mixture (e.g. a mixture containing clay soil and body soil as well as optionally dyes) which may contaminate other clothes washed in the washing liquor.

As used herein, the term "secondhand soil" means soils in the washing liquor during laundry process. The secondhand soil may lead to the formation of secondhand stain on fabrics during the laundry process.

As used herein, the term "secondhand soil composition" means a combination comprising at least clay soil and body soil which may stimulate the formation of a secondhand soil on fabrics in a washing liquor. The clay soil and the body soil may be present in a mixture or spatially separate. In the case that the clay soil and body soil are present separately, they can be separately added into water to form a washing liquor together with the detergent composition and the fabric. In some embodiments, the secondhand soil composition may further comprise a dye.

As used herein, the term "body soil" means body oils, dead skin flakes, sweat, desquamation, dander, sebum or any combinations thereof. There are some commercially available body soil, e.g. JB03 from Sino light inspection &certification Co. Ltd.

As used herein, the term "alkyl" means a hydrocarbyl moiety which is branched or unbranched, substituted or unsubstituted. Included in the term "alkyl" is the alkyl portion of acyl groups.

As used herein, the term “main surfactant” refers to a surfactant that is present in a composition at an amount that is greater than any other surfactant contained by such composition. Similarly, the term “main anionic surfactant” refers to an anionic surfactant that is present in a composition at an amount that is greater than any other anionic surfactant contained by such composition

As used herein, the term “majority surfactant” refers to a surfactant that is present in a composition at an amount that is at least 50%by weight of the total surfactant content in such composition. Similarly, the term “majority anionic surfactant” refers to an anionic surfactant that is present in a composition at an amount that is at least 50%by weight of the total anionic surfactant content in such composition.

As used herein, the term “washing liquor” refers to the typical amount of aqueous solution used for one cycle of laundry washing, preferably from 1 L to 50 L, alternatively from 1 L to 20 L for hand washing and from 20 L to 65 L for machine washing.

As used herein, the term “fabric” is used non-specifically and may refer to any type of natural or artificial fibers, including natural, artificial, and synthetic fibers, such as, but not limited to, cotton, linen, wool, polyester, nylon, silk, acrylic, and the like, as well as various blends and combinations.

Detergent Composition

The detergent compositions of the present disclosure may be selected from the group of detergent powder compositions, light duty liquid detergents compositions, heavy duty liquid detergent compositions, detergent gels commonly used for laundry, bleaching compositions, laundry additives, fabric enhancer compositions, unit dose articles, and mixtures thereof.

The composition may be in any suitable form. The composition may be in the form of a liquid composition, a granular composition, a single-compartment pouch, a multi-compartment pouch, a sheet, a pastille or bead, a fibrous article, a tablet, a bar, flake, or a mixture thereof. The composition can be selected from a liquid, solid, or combination thereof.

The composition can be an aqueous liquid laundry detergent composition. For such aqueous liquid laundry detergent compositions, the water content can be present at a level of from 5.0 %to 95 %, preferably from 25 %to 90 %, more preferably from 50 %to 85 %by weight of the liquid detergent composition.

The pH range of the detergent composition may be preferably from 6.0 to 8.9, more preferably from pH 7 to 8.8.

The detergent composition can also be encapsulated in a water-soluble film, to form a unit dose article. Such unit dose articles comprise a detergent composition of the present invention, wherein the detergent composition comprises less than 20%, preferably less than 15%, more preferably less than 10%by weight of water, and the detergent composition is enclosed in a water-soluble or dispersible film. Such unit-dose articles can be formed using any means known in the art. Suitable unit-dose articles can comprise one compartment, wherein the compartment comprises the liquid laundry detergent composition. Alternatively, the unit-dose articles can be multi-compartment unit-dose articles, wherein at least one compartment comprises the liquid laundry detergent composition.

Polyalkylene oxide graft copolymers

The detergent composition may comprise one or more polyalkylene oxide graft copolymers. The graft copolymer can be present at a level of from about 0.01%to about 15%, preferably from about 0.05%to about 10%, more preferably from about 0.1%to about 5%, and most preferably from about 0.2%to about 3%, e.g. 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 1%, 2%, or 3%, by weight of the composition.

In a particularly embodiment, the polyalkylene oxide graft copolymer comprises: (a) polyalkylene oxide which has a number average molecular weight of from 1000 to 20,000 Daltons and is based on ethylene oxide, propylene oxide, and/or butylene oxide, (b) polyvinyl ester component as side chains, and (c) polyvinylpyrrolidone as side chains. Particularly, the polyvinyl ester component is derived from a saturated monocarboxylic acid containing from 1 to 6 carbon atoms and/or a methyl or ethyl ester of acrylic or methacrylic acid.

In a particularly embodiment, the weight ratio of component a) to component b) is from 1: 0.1 to 1: 0.99, preferably from 1: 0.3 to 1: 0.9.

In a particularly embodiment, the weight ratio of component a) to component c) is from 1: 0.1 to 1: 2, preferably from 1: 0.3 to 1: 1.

In a particularly embodiment, in the polyalkylene oxide graft copolymer, from 1.0 mol%to 60 mol%, preferably from 20 mol%to 60 mol%, more preferably from 30 mol%to 50mol%of the grafted-on monomers of component (b) are hydrolyzed.

In a particularly embodiment, the polyalkylene oxide comprises or consists of ethylene oxide units or ethylene oxide units and propylene oxide units.

In a particularly embodiment, the polyvinyl ester comprises vinyl acetate.

Suitable polyalkylene oxides may be based on homopolymers or copolymers, with homopolymers being preferred. Suitable polyalkylene oxides may be based on homopolymers of ethylene oxide or ethylene oxide copolymers having an ethylene oxide content of from 40 mol%to 99 mol%. Suitable comonomers for such copolymers may include propylene oxide, n-butylene oxide, and/or isobutylene oxide. Suitable copolymers may include copolymers of ethylene oxide and propylene oxide, copolymers of ethylene oxide and butylene oxide, and/or copolymers of ethylene oxide, propylene oxide, and at least one butylene oxide. The copolymers may include an ethylene oxide content of from 40 to 99 mol%, a propylene oxide content of from 1.0 to 60 mol%, and a butylene oxide content of from 1.0 to 30 mol%. The graft base may be linear (straight-chain) or branched, for example a branched homopolymer and/or a branched copolymer.

Branched copolymers may be prepared by addition of ethylene oxide with or without propylene oxides and/or butylene oxides onto polyhydric low molecular weight alcohols, for example trimethylol propane, pentoses, or hexoses.

The alkylene oxide unit may be randomly distributed in the polymer or be present therein as blocks.

The polyalkylene oxides of component (a) may be the corresponding polyalkylene glycols in free form, that is, with OH end groups, or they may be capped at one or both end groups. Suitable end groups may be, for example, C1-C25-alkyl, phenyl, and C1-C14-alkylphenyl groups. The end group may be a C1-alkyl (e.g., methyl) group. Suitable materials for the graft base may include PEG 1000, PEG 2000, PEG 4000, PEG 6000, PEG 8000, PEG 10000, PEG 12000, and/or PEG 20000, which are polyethylene glycols, and/or MPEG 2000, MPEG 4000, MPEG 6000, MPEG 8000 and MEG 10000 which are monomethoxypolyethylene glycols that are commercially available from BASF under the tradename PLURIOLand/or block copolymers made from ethylene oxide-propylene oxide-ethylene oxide (EO-PO-EO) or from propylene oxide-ethylene oxide-propylene oxide (PO-EO-PO) such as PE 6100, PE 6800 or PE 3100 commercially available from BASF under the tradename PLURONIC.

The polyalkylene oxides may be grafted with N-vinylpyrrolidone as the monomer of component (b) . Without wishing to be bound by theory, it is believed that the presence of the N-vinylpyrrolidone ( “VP” ) monomer in the graft copolymers according to the present disclosure provides water-solubility and good film-forming properties compared to otherwise-similar polymers that do not contain the N-vinylpyrrolidone monomer. The vinyl pyrrolidone repeat unit has amphiphilic character with a polar amide group that can form a dipole, and a non-polar portion with the methylene groups in the backbone and the ring, making it hydrophobic.

The polyalkylene oxides may be grafted with a vinyl ester as the monomer of component (c) . The vinyl ester may be derived from a saturated monocarboxylic acid, which may contain 1 to 6 carbon atoms, or from 1 to 3 carbon atoms, or from 1 to 2 carbon atoms, or 1 carbon atom. Suitable vinyl esters may be selected from the group consisting of vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl iso-valerate, vinyl caproate, or mixtures thereof. Preferred monomers of component (c) include those selected from the group consisting of vinyl acetate, vinyl propionate, or mixtures thereof, preferably vinyl acetate.

Conventionally, molecular weights are expressed by their “K-values, ” which are derived from relative viscosity measurements. The graft copolymers may have a K value of from 5.0 to 200, optionally from 5.0 to 50, determined according to H. Fikentscher in 2%strength by weight solution in dimethylformamide at 25C.

Particularly preferred graft copolymers of the present invention have a polyethylene oxide backbone grafted with one or more side chains of polyvinyl acetate. More preferably, the weight ratio of the polyethylene oxide backbone over the polyvinyl acetate side chains ranges from about 1: 0.2 to about 1: 10, or from about 1: 0.5 to about 1: 6, and most preferably from about 1: 1 to about 1: 5. One example of such preferred amphiphilic graft copolymers is the Sokalan^TM HP22 polymer, which is commercially available from BASF Corporation. This polymer has a polyethylene oxide backbone grafted with polyvinyl acetate side chains. The polyethylene oxide backbone of this polymer has a number average molecular weight (Mn) of about 6,000 g/mol (equivalent to about 136 ethylene oxide units) , and the weight ratio of the polyethylene oxide backbone over the polyvinyl acetate side chains is about 1: 3. The number average molecular weight (Mn) of this polymer itself is about 24,000 g/mol.

Surfactant system

The composition according to the present disclosure may comprise from 1%to 99%, preferably from 4%to 80%, preferably from 6%to 50%, more preferably from 10%to 30%, e.g., 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%or any ranges therebetween, by weight of the composition, of a surfactant system. Particularly, the surfactant system may comprise an anionic surfactant and a nonionic surfactant.

Particularly, the anionic surfactant may comprise linear alkylbenzene sulfonate (LAS) , alkyl ethoxylated sulfates (AES) , alkyl sulfates (AS) , methyl ester sulfonates (MES) , alkyl ether carboxylates (AEC) , or any combinations thereof, preferably the anionic surfactant is selected from the group consisting of C₆-C₂₀ linear alkylbenzene sulfonate (LAS) , C₆-C₂₀ alkyl ethoxylated sulfates (AES) , C₆-C₂₀ alkyl sulfates (AS) , and any combinations thereof; and/or

Particularly, the nonionic surfactant may comprise alkyl alkoxylated alcohols, alkyl alkoxylated phenols, alkyl polysaccharides, polyhydroxy fatty acid amides, alkoxylated fatty acid esters, and any combinations thereof, preferably the nonionic surfactant is selected from the nonionic surfactants represented by Formula (1) :
R¹²-X- [ (EO) _s/ (PO) _t] -R¹³ ... (1)

wherein, R¹² is linear or branched alkyl having from 8 to 18 carbon atoms, X is -O-or -C (O) O-, R¹³ is hydrogen or alkyl having from 1 to 6 carbon atoms, s represents average repeats of EO, t represents average repeats of PO, s is from 3 to 20, t is from 0 to 6, EO represents ethylene oxide, PO represents propylene oxide, EO and PO may be arranged in mixture.

The anionic surfactant suitable for the composition in the present invention may be selected from the group consisting of C₆-C₂₀ linear alkylbenzene sulfonates (LAS) , C₆-C₂₀ alkyl sulfates (AS) , C₆-C₂₀ alkyl alkoxy sulfates (AAS) , C₆-C₂₀ methyl ester sulfonates (MES) , C₆-C₂₀ alkyl ether carboxylates (AEC) , and any combinations thereof. For example, the laundry detergent composition may contain a C₆-C₂₀ alkyl alkoxy sulfates (AA_xS) , wherein x is about 1-30, preferably about 1-15, more preferably about 1-10, most preferably x is about 1-3. The alkyl chain in such AA_xS can be either linear or branched, with mid-chain branched AA_xS surfactants being particularly preferred. A preferred group of AA_xS include C₁₂-C₁₄ alkyl alkoxy sulfates with x of about 1-3. In some embodiments, the composition comprises from 1%to 30%, preferably from 2%to 25%, more preferably from 3%to 20%, for example, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, or any ranges therebetween, by weight of the composition of the anionic surfactant.

The nonionic surfactant suitable for the composition in the present invention may be selected from the group consisting of alkyl alkoxylated alcohols, alkyl alkoxylated phenols, alkyl polysaccharides, polyhydroxy fatty acid amides, alkoxylated fatty acid esters, sucrose esters, sorbitan esters and alkoxylated derivatives of sorbitan esters, and any combinations thereof. Non- limiting examples of nonionic surfactants suitable for use herein include: C₁₂-C₁₈ alkyl ethoxylates, such asnonionic surfactants available from Shell; C₆-C₁₂ alkyl phenol alkoxylates wherein the alkoxylate units are a mixture of ethyleneoxy and propyleneoxy units; C₁₂-C₁₈ alcohol and C₆-C₁₂ alkyl phenol condensates with ethylene oxide/propylene oxide block alkyl polyamine ethoxylates such asavailable from BASF; C₁₄-C₂₂ mid-chain branched alkyl alkoxylates, BAEx, wherein x is from about 1 to about 30; alkylpolysaccharides, specifically alkylpolyglycosides; polyhydroxy fatty acid amides; and ether capped poly (oxyalkylated) alcohol surfactants. Also useful herein as nonionic surfactants are alkoxylated ester surfactants such as those having the formula R¹C (O) O (R₂O) nR³ wherein R¹ is selected from linear and branched C₆-C₂₂ alkyl or alkylene moieties; R² is selected from C₂H₄ and C₃H₆ moieties and R³ is selected from H, CH₃, C₂H₅ and C₃H₇ moieties; and n has a value between about 1 and about 20. Such alkoxylated ester surfactants include the fatty methyl ester ethoxylates (MEE) and are well-known in the art. In some particular embodiments, the alkoxylated nonionic surfactant contained by the laundry detergent composition of the present invention is a C₆-C₂₀ alkoxylated alcohol, preferably C₈-C₁₈ alkoxylated alcohol, more preferably C₁₀-C₁₆ alkoxylated alcohol. The C₆-C₂₀ alkoxylated alcohol is preferably an alkyl alkoxylated alcohol with an average degree of alkoxylation of from about 1 to about 50, preferably from about 3 to about 30, more preferably from about 5 to about 20, even more preferably from about 5 to about 9. In some embodiments, the composition comprises from 1%to 30%, preferably from 2%to 25%, more preferably from 3%to 20%, for example, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, or any ranges therebetween, by weight of the composition of the nonionic surfactant.

The ratio of anionic surfactant to nonionic surfactant may be between 0.01 and 100, preferably between 0.05 and 20, more preferably between 0.1 and 10, and most preferably between 0.2 and 5.

In some embodiments, the anionic surfactant comprises a C₆-C₂₀ linear alkylbenzene sulfonate surfactant (LAS) , preferably C₁₀-C₁₆ LAS, and more preferably C₁₂-C₁₄ LAS. In other embodiments, the anionic surfactant comprises a C₆-C₂₀ alkyl alkoxy sulfates (AAS) , preferably C₁₀-C₁₆ AAS, and more preferably C₁₂-C₁₄ AAS. In other embodiments, the anionic surfactant comprises a C₆-C₂₀ alkyl sulfates (AS) , preferably C₁₀-C₁₆ AS, and more preferably C₁₂-C₁₄ AS.

In some particular embodiments of the present invention, the anionic surfactant may be present as the main surfactant, preferably as the majority surfactant, in the composition. Preferably, the ratio of anionic surfactant to nonionic surfactant may be between 1.05 and 100, preferably between 1.1 and 20, more preferably between 1.2 and 10, and most preferably between 1.3 and 5. Particularly, the anionic surfactant may comprise C₆-C₂₀ linear alkylbenzene sulfonates (LAS) .

In some particular embodiments of the present invention, the nonionic surfactant may be present as the main surfactant, preferably as the majority surfactant, in the composition. Preferably, the ratio of anionic surfactant to nonionic surfactant may be between 0.01 and 0.95, preferably between 0.05 and 0.9, more preferably between 0.1 and 0.85, and most preferably between 0.2 and 0.8. Particularly, the nonionic surfactant may comprise C₆-C₂₀ alkoxylated alcohol.

The laundry detergent composition of the present invention may further comprise a cationic surfactant. Non-limiting examples of cationic surfactants include: quaternary ammonium surfactants, which can have up to 26 carbon atoms include: alkoxylate quaternary ammonium (AQA) surfactants; dimethyl hydroxyethyl quaternary ammonium compounds; dimethyl diisopropyl quaternary ammonium compounds; dimethyl hydroxyethyl lauryl ammonium chloride; polyamine cationic surfactants; and amino surfactants, specifically amido propyldimethyl amine (APA) .

The laundry detergent composition of the present invention may further comprise an amphoteric surfactant. Non-limiting examples of amphoteric surfactants include: amine oxides, derivatives of secondary and tertiary amines, derivatives of heterocyclic secondary and tertiary amines, or derivatives of quaternary ammonium, quaternary phosphonium or tertiary sulfonium compounds. Preferred examples include: C₆-C₂₀ alkyldimethyl amine oxides, betaine, including alkyl dimethyl betaine and cocodimethyl amidopropyl betaine, sulfo and hydroxy betaines, such as N-alkyl-N, N-dimethylammino-1-propane sulfonate where the alkyl group can be C₈-C₁₈ or C₁₀-C₁₄.

Other ingredients

The laundry detergent composition according to the present disclosure may further comprise from 0.01%to 10%, preferably from 0.1%to 5%, more preferably from 0.2%to 3%, most preferably from 0.3%to 2%, by weight of the composition, of a surfactant boosting polymer, preferably polyvinyl acetate grafted polyethylene oxide copolymer.

The laundry detergent composition herein may comprise adjunct ingredients. Suitable adjunct materials include but are not limited to: builders, chelating agents, rheology modifiers, dye transfer inhibiting agents, dispersants, enzymes, and enzyme stabilizers, anti-oxidants, catalytic materials, bleach activators, hydrogen peroxide, sources of hydrogen peroxide, preformed peracids, polymeric dispersing agents, clay soil removal/anti-redeposition agents, brighteners, suds suppressors, dyes, photobleaches, perfumes, perfume microcapsules, structure elasticizing agents, fabric softeners, carriers, hydrotropes, processing aids, solvents, hueing agents, structurants and/or pigments. The precise nature of these adjunct ingredients and the levels thereof in the laundry detergent composition will depend on the physical form of the composition and the nature of the cleaning operation for which it is to be used.

In some embodiments, the laundry detergent composition according to the present disclosure may further comprise from 0.01%to 10%, preferably from 0.1%to 5%, more preferably from 0.2%to 4%, most preferably from 0.3%to 3%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%or any ranges thereof, by weight of the composition, of a fatty acid.

Composition Preparation

The laundry detergent composition of the present invention is generally prepared by conventional methods such as those known in the art of making laundry detergent compositions. Such methods typically involve mixing the essential and optional ingredients in any desired order to a relatively uniform state, with or without heating, cooling, application of vacuum, and the like, thereby providing laundry detergent compositions containing ingredients in the requisite concentrations.

Method of Use

Another aspect of the present invention is directed to a method of using the laundry detergent composition to treat mixed fabrics. Such method can deliver a benefit for preventing the formation of secondhand stain. The method comprises the step of administering from 5 g to 120 g of the above-mentioned laundry detergent composition into a laundry washing basin comprising water to form a washing solution. The washing solution in a laundry washing basin herein preferably has a volume from 1 L to 65 L, alternatively from 1 L to 20 L for hand washing and from 10 L to 65 L for machine washing. The temperatures of the laundry washing solution preferably range from 5℃ to 60℃.

The dosing amount in the method herein may be different depending on the washing type. In one embodiment, the method comprises administering from about 5 g to about 60 g of the laundry detergent composition into a hand washing basin (e.g., about 2-4 L) . In an alternative embodiment, the method comprises administering from about 5 g to about 100 g, preferably from about 10 g to about 65 g of the laundry detergent composition into a washing machine (e.g., about 10-45 L) .

Test Method

Test 1: Whiteness Maintenance Index Test for Secondhand Soil Composition

Whiteness Maintenance Index test is conducted by using Tergotometer (Model: NE6-COP, from Copley Scientific Ltd) as below:

Clay soil: Arizona dust clay having an average particle size of around 0.5-2μm, available from Shanghai Rainbow Technology Ltd Co., 0.75g/L

Body soil: JB03 nil carbon black, available from Sino light inspection &certification Co. Ltd., 0.15g/L to 2.25g/L

Dye: Reactive Red 3BS and Reactive Black WNN, available from Zhejiang Longsheng Ltd. Co.

The weight ratio of clay soil to body soil is from 5: 1 to 1: 3, preferably 1: 2.

The dose of dyes is from 5 ppm to 300 ppm, preferably 12 ppm Reactive Red and 30 ppm Reactive Black.

Water volume: 0.8L

Water type: city water

Detergent composition Concentration: 2000 ppm

Fabric Tracer: 10cm x 10cm with-brightener PCW13 (50%Cotton 50%Polyester, purchased from Danxin Textile Co. Beijing, China) , 2 pieces, which were pre-stripped with China National Standard powder detergent (from Taiyuan, China) in DI water by 6 times

Measure the L*ab (and then calculate ΔE which is designated as Whiteness Maintenance Index) of the fabric tracers before washing.

1, Add city water

2, Add HDL and dissolve for 1 minutes.

3, Add the clay soil and dissolve for 3 minutes.

4, Add the body soil (and optionally dyes) and dissolve for 5 minutes, in which a dye solution is formulated by respectively adding dye powder into RO water in advance.

5, Put in fabric tracers and start stirring (main wash) .

6, The main wash time is 10 minutes.

7, Rinse once after the main wash.

8, The rinse time is 3 minutes.

9, Remove the fabrics from the rinse container and natural air.

10, Measure the L*ab of the tracer washed with detergent and the clay by using IA measurement, and calculate the ΔE.

Test 2: Conventional Clean Test

Clay soil (Arizona dust clay having an average particle size of around 0.5-2μm) , available from Shanghai Rainbow Technology Ltd Co., 0.75g/L

Water volume: 0.8L

Water type: city water

Detergent composition Concentration: 2000 ppm

1, Add city water

2, Add HDL and dissolve for 1 minutes.

3, Add the clay soil and dissolve for 3 minutes.

4, Put in fabric tracers and start stirring (main wash) .

5, The main wash time is 10 minutes.

6, Rinse once after the main wash.

7, The rinse time is 3 minutes.

8, Remove the fabrics from the rinse container and natural air.

9, Measure the L*ab of the tracer washed with detergent and the clay by using IA measurement, and calculate the ΔE.

Test 3: Whiteness Grade test data

The score of from -2 to 2 was given by five panelists to observe the whiteness of the fabric between Test Sample and Reference Sample, in which negative number means that panelists have a high rating for Reference Sample, positive number means that panelists have a high rating for Test Sample and 0 point means no difference between Samples.

EXAMPLES

Synthesis Example 1: Synthesis of Graft Copolymer

A graft copolymer which is PVP/PVAc-g-PEG at a weight ratio of 20: 30: 50 ratio with a weight average molecular weight 16, 800 Dalton was prepared as follows.

A polymerization vessel equipped with stirrer and reflux condenser was initially charged with 720g of PEG (6000 g/mol) and 60g 1, 2-propane diol (MPG) under nitrogen atmosphere. The mixture was homogenized at 70℃.

Then, 432 g of vinyl acetate (in 2 h) , 288 g of vinylpyrrolidone in 576 g of MPG (in 5 h) , and 30.2 g of tert. -butyl perpivalate in 196.6 g MPG (in 5.5 h) were metered in. Upon complete addition of the feeds, the solution was stirred at 70℃ for 1 h. Subsequently, 3.8 g tert. -butyl perpivalate in 25.0 g MPG (in 1.5 h) were metered in followed by 0.5 h of stirring.

The volatiles were removed by vacuum stripping. Then, 676.8 g deionized water were added and a steam distillation was conducted at 100℃ for 1 h.

The temperature of the reaction mixture was reduced to 80℃ and 160.6 g of aqueous sodium hydroxide solution (50 %, 40 mol%respective VAc) was added with maximum feed rate. Upon complete addition of the sodium hydroxide solution, the mixture was stirred for 1 h at 80℃ and subsequently cooled to ambient temperature.

The resulting graft copolymer is characterized by a K-value of 24. The solid content of the final solution is 45 %.

Example 1: Establishment of Method for Evaluating Prevention of Formation of Secondhand Stain

In order to understand the reasons why clothes turn grey and/or dull after washing, an analysis of washing liquor was conducted for consumers who reported the issue as mentioned above. 30 samples of washing liquor were collected from 30 consumers. Soil levels and soil compositions in the washing liquor samples were determined. The average total soil level was 200 mg/L which is much higher than the soil level (～ 60mg/L) used in standard laundry cleaning test (SBL2004) . The composition of soil is shown below. Proteins and lipids usually come from body soil. In standard laundry cleaning test (SBL2004) , proteins and lipids are underrepresented.

Table 1

Furthermore, the particle size was determined for the washing liquor samples. The median particle size is 41μm which is much smaller than the average particle size of soil (～77 μm) used in standard laundry cleaning test (SBL2004) .

As such, it was realized by the present inventors that the presence of secondhand soil (i.e., soil in the washing liquor containing the mixture of clay soil and body soil as well as optionally dyes) might be the reason of clothes turning grey and/or dull after washing. In other words, the secondhand soil in the washing liquor leads to the formation of secondhand stain on fabrics. Accordingly, the present inventors developed a method of evaluating the efficacy of a detergent composition for preventing formation of secondhand stain on fabrics, in which the combination of clay soil and body soil at a certain ratio (e.g. from 5: 1 to 1: 3) as well as optionally a dye is added into the washing liquor to simulate the formation of secondhand stain. Particularly, four Secondhand Soil Compositions (SSC) , SSC 1 to 4, were formulated as shown below.

Table 2

1 Clay soil: Arizona dust clay having an average particle size of around 0.5-2μm, available from Shanghai
Rainbow Technology Ltd Co., .
2 Body soil: JB03 nil carbon black, available from Sino light inspection &certification Co. Ltd.

In order to test if the Secondhand Soil Compositions can simulate the formation of secondhand stain during the washing, a sample liquid detergent composition (Sample 1) based on National Standard Liquid (NSL) laundry detergent was tested by using SSC 1 in accordance with Test 1: Whiteness Maintenance Index Test for Secondhand Soil Composition and Test 2: Conventional Clean Test. The results indicate that although the cleaning performance of Sample 1 under the conventional condition (i.e., the test result according to Test 2) is very good, the cleaning performance of Sample 1 for secondhand soil composition (i.e., the test result according to Test 1) is quite poor (3.4 vs. 13.8) , which is consistent with the experiences of consumers. Thus, the Secondhand Soil Compositions are useful in evaluating prevention of formation of secondhand stain.

Table 3

Example 2: Improved Secondhand Stain Prevention in Laundry Detergent Composition Containing Polyalkylene Oxide Graft Copolymer

Two (2) sample liquid laundry detergent compositions were prepared containing the following ingredients, in which Sample 2 contains a polyalkylene oxide graft copolymer while Sample 3 does not contain such graft copolymer.

Table 4

1 Polyalkylene oxide graft copolymer described in Synthesis Example 1 with PVP/PVAc-g-PEG at a
weight ratio of 20: 30: 50 ratio with a weight average molecular weight 16,800 Dalton.

In accordance with Test 1: Whiteness Maintenance Index Test for Secondhand Soil Composition as described hereinabove, △E for Samples 2 and 3 were measured by using SSC 1 to SSC 4 as mentioned in Example 1. Surprisingly, sample 2 containing a graft copolymer shows significantly improved secondhand stain prevention compared to Sample 3 without such graft copolymer, as shown in the Table 5 below.

Table 5

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm. ”

Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

A method of evaluating the efficacy of a detergent composition for preventing formation of a secondhand stain on fabrics, the method comprising the steps of:

A) providing a secondhand soil composition, a fabric, and the detergent composition to be evaluated;

B) adding the secondhand soil composition, the fabric and the detergent composition to be evaluated into water to form a washing liquor;

C) washing the fabric in the washing liquor; and

D) measuring Whiteness Maintenance Index of the fabric,

wherein the secondhand soil composition comprises clay soil and body soil in which the weight ratio of the clay soil to the body soil is from 5: 1 to 1: 3.
The method according to Claim 1, wherein the weight ratio of the clay soil to the body soil is from 4: 1 to 1: 3, preferably from 3: 1 to 1: 2.5, more preferably from 2: 1 to 1: 2.5, and most preferably from 1: 1 to 1: 2.5.
The method according to Claim 1 or 2, wherein the secondhand soil composition is present in the washing liquor at a level of from 0.03g/L to 15g/L, preferably from 0.1g/L to 10g/L, more preferably from 0.3g/L to 5g/L, even more preferably from 0.5g/L to 2g/L.
The method according to any one of Claims 1 to 3, wherein the secondhand soil composition further comprises a dye which is at a level of from of from 0.001wt%to 1.5wt%, preferably from 0.03wt%to 0.5wt%, more preferably from 0.05wt%to 0.3wt%, by the total weight of the secondhand soil composition.
The method according to Claim 4, wherein in the washing liquor the clay soil is present at a level of from 0.05g/L to 12g/L, preferably from 0.2g/L to 5g/L, more preferably from 0.3g/L to 2g/L; and/or

wherein in the washing liquor the body soil is present at a level of from 0.05g/L to 12g/L, preferably from 0.2g/L to 5g/L, more preferably from 0.3g/L to 2g/L; and/or

wherein in the washing liquor the dye is present at a level of from 0.0005g/L to 1g/L, preferably from 0.001g/L to 0.5g/L, more preferably from 0.005g/L to 0.2g/L.
The method according to any of preceding claims, wherein the fabric is selected from the group consisting of cotton, polycotton, regenerated cotton, synthetically modified cotton, linen, wool, polyester, nylon, elastane, silk, acrylic, and any combinations thereof.
The method according to any of preceding claims, wherein the fabric is cotton, polycotton, regenerated cotton, synthetically modified cotton, polyester, nylon, elastane, or any combinations thereof.
The method according to any of preceding claims, wherein the detergent composition comprises a treatment adjunct which is preferably selected from the group consisting of a surfactant system, fatty acids and/or salts thereof, enzymes, encapsulated benefit agents, soil release polymers, hueing agents, builders, chelating agents, dye transfer inhibiting agents, dispersants, enzyme stabilizers, anti-oxidants, catalytic materials, bleaching agents, bleach catalysts, bleach activators, polymeric dispersing agents, soil removal/anti-redeposition agents, polymeric grease cleaning agents, amphiphilic copolymers, brighteners, suds suppressors, dyes, hueing agents, perfume, structure elasticizing agents, fabric softeners, carriers, fillers, hydrotropes, solvents, anti-microbial agents and/or preservatives, neutralizers and/or pH adjusting agents, processing aids, rheology modifiers and/or structurants, opacifiers, pearlescent agents, pigments, anti-corrosion and/or anti-tarnishing agents, and mixtures thereof.
The method according to any of preceding claims, wherein the secondhand stain is a stain on fabric which is formed during the washing of the fabric, preferably wherein the secondhand stain is a stain on fabric which is formed by a mixture of clay soil and body soil as well as optionally a dye during the washing of the fabric.
The method according to any of preceding claims, wherein the Whiteness Maintenance Index of the fabric is determined by measuring L*AB and calculating ΔE as the Whiteness Maintenance Index, preferably wherein the Whiteness Maintenance Index of the fabric is determined in accordance with Test 1: Whiteness Maintenance Index Test for Secondhand Soil Composition.
A method for preventing formation of a secondhand stain on fabrics, the method comprising the steps of:

A) providing fabrics;

B) treating the fabrics with a detergent composition comprising from about 0.05%to about 15%, preferably from about 0.1%to about 5%, more preferably from about 0.2%to about 3%, by weight of the detergent composition, of a polyalkylene oxide graft copolymer comprising:

a) polyalkylene oxide component as a graft base in which the polyalkylene oxide has a number average molecular weight of from 1000 to 20,000 Daltons and is based on ethylene oxide, propylene oxide, butylene oxide or mixtures thereof,

b) polyvinyl ester component as side chains in which the polyvinyl ester is derived from a saturated monocarboxylic acid containing from 1 to 6 carbon atoms and/or a methyl or ethyl ester of acrylic or methacrylic acid, and

c) polyvinylpyrrolidone as side chains,

wherein the weight ratio of (a) : (c) is from 1: 0.1 to 1: 2, and

wherein the amount, by weight, of (a) is greater than the amount of (b) .
A method for laundering fabric, the method comprising the steps of:

A) providing mixed fabrics and a detergent composition;

B) adding the mixed fabrics and the detergent composition into water to form a washing liquor; and

C) washing the mixed fabrics in the washing liquor,

wherein the detergent composition comprises from about 0.05%to about 15%, preferably from about 0.1%to about 5%, more preferably from about 0.2%to about 3%, by weight of the detergent composition, of a polyalkylene oxide graft copolymer comprising:

a) polyalkylene oxide component as a graft base in which the polyalkylene oxide has a number average molecular weight of from 1000 to 20,000 Daltons and is based on ethylene oxide, propylene oxide, butylene oxide or mixtures thereof,

b) polyvinyl ester component as side chains in which the polyvinyl ester is derived from a saturated monocarboxylic acid containing from 1 to 6 carbon atoms and/or a methyl or ethyl ester of acrylic or methacrylic acid, and

c) polyvinylpyrrolidone as side chains,

wherein the weight ratio of (a) : (c) is from 1: 0.1 to 1: 2, and

wherein the amount, by weight, of (a) is greater than the amount of (b) .