ZA200305614B

ZA200305614B - Soil release polymers and laundry detergent compositions containing them.

Info

Publication number: ZA200305614B
Application number: ZA200305614A
Authority: ZA
Inventors: Sudhir Achar; Velayudhan Nair Gopa Kumar
Original assignee: Unilever Plc
Priority date: 2001-03-02
Filing date: 2003-07-21
Publication date: 2004-07-21
Also published as: GB0110778D0

Description

) SOIL RELEASE POLYMERS AND LAUNDRY DETERGENT ] COMPOSITIONS CONTAINING THEM i

TECHNICAL FIELD

The present invention relates to a novel modified polysaccharide and a process for its preparation. The polysaccharide of the invention provides improved detergency benefits, enhanced release of specific soils and specific benefits to the fabric when used in detergent formulations or rinse compositions.

BACKGROUND OF THE INVENTION

When laundry fabrics are washed with a detergent, to give complete cleaning, the detergent must first remove the soil particles from the fabric and suspend them in the soil solution and then prevent soil particles and other insoluble particles from re-depositing on the fabric during the washing and rinsing of the fabric. Since conventional detergent formulations give incomplete soil removal, additives need to be added to improve soil removal and ease the release of soil and/or to prevent re-deposition of the soil.

Polymers can be added to detergent formulations to enhance . soil removal from the fabric as well as prevent re-deposition of soil. Soil release polymers (SRPs) adsorb onto a fabric . surface assisting soil removal while anti-redeposition polymers (ARDs) stabilise the soil in the wash solution thus preventing redeposition of the soil.

Most soil release polymers disclosed in the prior art are . synthetic polymers. Examples of these polymers are hydrophilic polyesters and cross-linked acrylic polymers.

Anti-redeposition polymers known in the art are sodium carboxymethyl cellulose and methyl cellulose amongst others.

Soil release polymers disclosed in the literature address the problem of removal of oily or fatty soils from polyester and cotton, in particular polyester while anti-redeposition polymers conventionally address the problem of redeposition of particulate soils.

Polysaccharides are biodegradable, natural polymers with extensive hydroxyl groups. Polysaccharides can be readily modified to give polymers with desired characteristics and such modified polysaccharides have been used extensively in the chemical industry. Modified polysaccharides have been used in detergent formulations as anti-redeposition agents, builders and to encapsulate detergent actives, amongst other functions. However, their use in detergents is limited to conventional molecules well known in the art.

In addition to improved detergency, it is also desirable to impart properties like stiffness and anti-wrinkling benefits to the fabric. Smoothness of the fabric after washing is another desired attribute. While natural polymers like . starch can be used for stiffening and some rinse conditioners are known to impart smoothness and anti-wrinkling benefits, * it has so far not been possible to impart all these benefits along with soil release, anti-redeposition and detergency improvement.

‘ Thus, there is a need in the detergent industry for polymer additives that can improve detergency as well as impart other desirable properties. The applicants have now found that certain phosphated, hydrophobically modified polysaccharides give benefits when incorporated into laundry treatment compositions. The polymers can be used as rinse conditioners, improving consequent soil removal, imparting a stiff feel to the fabric and giving anti-wrinkling and improved ironability benefits. The modified polysaccharides can also be incorporated into detergent formulations and give superior detergency for cotton, polyester and their blends and impart smoothness to the fabric.

PRIOR ART

JP 56 112901A (Kyoritsu Yuki Kogyo) discloses a wet process to make a starch phosphate by reacting a phosphoric acid and an epihalohydrin with starch in the presence of an alkali or alkaline earth metal hydroxide. The starch phosphate can be used as a detergent builder.

GB 2 322 137A (Unilever) discloses the hydrophobic modification of starch (starch is the hydrophilic segment) and its use as a soil release polymer, in particular for . detergency of oily soil from polyester fabric. Hydrophobic modification was carried out by graft copolymerising starch \ with hydrophobic monomers.

WO 01/88075A (Unilever), published 11 November 2001, describes polysaccharides that are modified by (a)

\ hydrophobic modification and (b) carboxylation and/or sulphonation, as soil release polymers for detergent formulations.

GB 1 568 688 (Stadex) and US 5 334 287 (Hartmann et al/

BASF) are disclosures in a non-laundry context of graft copolymers of polysaccharides, including starch.

DEFINITION OF THE INVENTION

According to a first aspect of the invention, a phosphated, hydrophobic graft copolymer of polysaccharide having the general formula I is provided: === ==(6)——(6)——(G)——(G)----- m

R wherein R is a hydrophobic vinyl polymer, R’ represents a phosphate group or its salt and G is a monosaccharide or substituted monosaccharide.

According to a second aspect of the invention, there is ) 30 provided a process for the preparation of a phosphated, hydrophobic graft copolymer of polysaccharide as defined in the previous paragraph, which process comprises (a) reacting a polysaccharide with an ethylenically unsaturated monomer to form a copolymer having a polysaccharide backbone

A

- 5 = ) carrying grafted hydrophobic vinyl polymeric groups derived from the ethylenically unsaturated monomer, (b) before or ¢ after step (a), reacting the polysaccharide or copolymer with a phosphating agent.

According to a third aspect of the invention, there are provided fabric treatment and detergent compositions as defined below.

DETAILED DESCRIPTION OF THE INVENTION

All parts and percentages are by weight unless otherwise indicated.

The phosphated, hydrophobic graft copolymer of polysaccharide of the current invention has the general structure given in formula I.

The Phosphate Group

The phosphate group is attached to the polysaccharide backbone through the hydroxyl group, either primary or secondary. It is not essential that the phosphate group be present on each of the sugar rings.

In a first embodiment the phosphate group, R’, has the . general formula II: ——0—P—0 / \ (II)

Xi X wherein each of Xj; and X3, which may be the same or different, is selected from ONa, OH, Cl or OG where G is another polysaccharide backbone thereby providing a cross-linked polymer.

In an alternative second embodiment the phosphate group, R’, has the general formula III: —O— PRY. (III) 7 \

Y,4 | Ys;

Ya

Wherein each of Yj, Y2, Y3 and Y4, which may be the same or different, is selected from Cl or OG where G is another polysaccharide backbone thereby providing a cross-linked polymer.

The groups R’ are derived from reaction with a phosphating agent. Preferred examples of phosphating agents are phosphoric acid, sodium tripolyphosphate (STPP), tetrasodium pyrophosphate, phosphorous pentachloride, phosphoryl chloride, sodium trimetaphosphate, polymeric sodium orthophosphates or their mixtures thereof. Preferably STPP is used as a phosphating agent. ’ The ratio by weight of the polysaccharide to the phosphate substituent is from 1:1 to 1:0.001, more preferably from 1:0.5-1:0.01 and most preferably from 1:0.3 to 1:0.1.

- 7 =

The Polysaccharide

In formula I, G, the repeating unit of the polysaccharide, is a monosaccharide or substituted monosaccharide. It is preferable that G is a monosaccharide.

The polysaccharide is preferably chosen from starch, modified starches, cellulose, guar gum, and tamarind gum but is not limited by the same. More preferably the polysaccharide is starch. The starch can be any native starch and includes those derived from wheat, rice, oat, tapioca, maize, potato, sorghum, arrowroot or their mixtures thereof. Alternatively, acid or enzymatically degraded starch or oxidised starch or their mixtures or their mixtures thereof with the native starches can also be used.

When starch is the preferred polysaccharide, it may be in the native form or gelatinised form. The term gelatinisation refers to rupture of the starch granule at elevated temperatures in presence of water.

It is not essential to remove any unreacted polysaccharide that may be present in the final product obtained by graft copolymerisation and esterification of the polysaccharide. . The Hydrophobic Vinyl Polymer . The hydrophobic modification is provided by a hydrophobic vinyl polymer (R in formula I) grafted onto the polysaccharide backbone. The hydrophobic vinyl polymer can be attached to the polysaccharide backbone through the hydroxyl group or through any of the carbon atoms on the monosaccharide or substituted monosaccharide. The polymer chains can be present at irregular intervals on the polysaccharide chain and it is not critical that they be present at regular intervals. If the homopolymer is formed, it may be present without impairing detergency.

The polymers of vinyl monomers like hydrophobic acrylic monomers, vinyl acetate, styrene and substituted styrenes are especially preferred. The molecular weight of each of the hydrophobic vinyl polymer chains is preferably 500- 5,000,000, more preferably from 2000-500,000 and most preferably from 5000-100, 000.

The amount of the hydrophobic vinyl polymer is from 0.01 to 10% by weight of the polysaccharide, more preferably from 1 to 5% by weight of the polysaccharide.

Preferably, hydrophobic acrylic monomers are used for graft copolymerisation. The hydrophobic acrylic polymers suitable for the present invention are shown in formula IV.

I I

— " (IV) : Ra Ry’ n wherein each of R; and R1 , which may be the same or , different, represents -H, -CH3 or -CyHs, and wherein each of Rz and Ry’, which may be the same or different, represents -COOCH3, —-COOCzHg or -COOCs3H7.

Particularly preferred is poly (methyl methacrylate) wherein

Ry = R1’=-CH3 and R; = Rp, = -COOCH3.

Optional Cationic Modification

Optionally, the soil release polymer of the invention may be treated with a cationic reagent. Examples of suitable cationic reagents are tertiary amino compounds, quaternary ammonium compounds and quaternary imidazolinium compounds and include epoxy propyl trimethyl ammonium chloride, 3-chloro-2- hydroxy propyl trimethyl ammonium chloride, 3-chloro-2- hydroxy propyl dimethyl dodecyl ammonium chloride and 3- chloro-2-hydroxy propyl dimethyl octadecyl ammonium chloride amongst others.

Preferably, the amount of the cationic substituent should not exceed 15% by weight with respect to the polysaccharide.

The polymers so prepared are especially useful for improving detergency from cotton.

Polymer Mixtures

Optionally, the soil release polymers of the invention may be mixed with other polymers to give a further improvement in detergency. Examples of such polymers are hydrophilic

- 1 0 - polyesters like GEROL (Trade Mark) and REPEL-O-TEX (Trade

Mark) and cross linked acrylic polymers like K-SAM-GE 500F (Trade Mark) and SANWET (Trade Mark). Especially preferred polymers are cross-linked acrylic polymers.

Examples of Preferred Modified Polysaccharides

The following formulae are representative examples of the hydrophobic, phosphated polysaccharides of the invention.

In the drawings, R has the meaning given previously, and most preferably represents

I" i)

TU "

R; R2 n where Rj preferably represents -CH3z and Rz preferably represents -COOCH3 and R’ has the meaning given previously and most preferably represents

OR

NaO ONa obtained when STPP is used as a phosphating agent.

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’ Preparation of the Phosphated, Hydrophobic Polysaccharides

The modified polysaccharides of the invention are prepared by a) reacting a polysaccharide with an ethylenically unsaturated monomer to form a copolymer having a polysaccharide backbone carrying grafted hydrophobic vinyl polymeric groups derived from the ethylenically unsaturated monomer, and b) before or after step (a), reacting the polysaccharide or copolymer with a phosphating agent.

It is not particularly relevant for the present invention as to which step is carried out first. Preferably, the step of graft copolymerisation of the polysaccharide is carried out first, followed by phosphation.

Both graft copolymerisation and phosphation of the polysaccharide can take place through the primary and/or the secondary hydroxyl groups on the polysaccharide backbone.

Graft copolymerisation can also be initiated by H abstraction from the monosaccharide residue.

Graft copolymerisation may be carried out by contacting a redox initiator, such as ferrous ammonium sulphate and hydrogen peroxide or ceric ammonium nitrate and dilute nitric acid, with the polysaccharide in an aqueous medium. A . preferred temperature range is 20-60°C, more preferably from 30-40°c. It is preferable to add an entrainer, an example of which is urea. When the ferrous ammonium sulphate and hydrogen peroxide system is used as the redox initiator, it is preferable also to add ascorbic acid. The hydrophobic monomer is added and subsequent polymerisation takes place to yield the polymer of the invention.

The hydrophobic graft copolymer so prepared is preferably reacted with a phosphating reagent selected from phosphoric acid, sodium tripolyphosphate (STPP), tetrasodium pyrophosphate, phosphorous pentachloride, phosphoryl chloride, sodium trimetaphosphate, polymeric sodium orthophosphates and mixtures thereof. It is most preferable to use STPP as a phosphating agent.

The ratio by weight of the polysaccharide to the phosphate substituent is from 1:1 to 1:0.001, more preferably from 1:0.5-1:0.01 and most preferably from 1:0.3 to 1:0.1.

Optionally the process may include treatment with a cationic reagent as discussed previously.

Several methods are known in the art to make phosphated polysaccharides. Methods as disclosed in Modified Starches,

Properties and uses, ed. O0.B. Wurzburg, 1986, page 98-103, . while being specifically directed towards modified starches, remain suitable for the invention.

In a preferred method of phosphating the polysaccharide, an acidic solution of STPP, of pH not greater than 6.5, is sprayed onto the polysaccharide or the graft copolymerised polysaccharide. The moisture content is then reduced to 25% or below and the mixture heated at a temperature of at least 35°C for at least 30 minutes.

When the polymer of the invention is prepared from native starch, it is preferred to prepare a slurry of the polymer in water followed by a conventional method of drying like drum drying or spray drying. The polymer so obtained is in a cold water soluble form.

Fabric Treatment Compositions

The polymers of the invention can be used in fabric treatment compositions such as rinse conditioners and can be conveniently supplied in the form of a powder, paste, flakes or a solution. In use, they can be applied as a solution to the fabric. When supplied as a solution, they may be suitably supplied in the form of aqueous compositions.

Preferably the fabric treatment compositions contain from 0 to 60 wt%, more preferably from 1 to 60 wt%, of a fabric treatment agent and the amount of the polymer, or a polymer mixture as previously described, is from 0.001 to 10%, more preferably from 0.25 to 5%. Optionally, other rinse conditioners, fabric softeners, perfumes and required ' stabilisers may also be added to the fabric treatment composition. In addition, optical brightening agents, colourants, opacifiers, hydrotropes, viscosity control agents and other anti-static agents and ironing aids may be present without affecting the performance of the polymer of the invention.

] Once the rinse conditioner is applied, subsequent washing will result in improved detergency. The polymers also impart stiffening akin to that of native polysaccharides like starch and guar gum and additionally impart anti- wrinkling benefits to the fabric.

Detergent Compositions

The polymer can also be incorporated into detergent compositions using conventional methods. When used in detergent formulations, the polymers give improved detergency and also impart a smooth feel to the fabric.

The detergent formulations may also contain, as in conventional formulations, detergent actives (surfactants) and builders.

The detergent composition may be in the form of a powder, bar, paste or liquid. Preferably the detergent composition contain from 0.001 to 10%, preferably from 0.25 to 5% of the polymer, or a polymer mixture as previously described.

The surfactant is generally chosen from anionic, nonionic, cationic, amphoteric and zwitterionic surfactants and mixtures thereof. It is preferred that from 5 to 60 wt% of ] the surfactant is incorporated in the formulation, more preferably from 5 to 40 wt%. Optionally the detergent : composition may also contain from 1 to 50 wt% of a detergency builder.

: Other ingredients include sequestrants, dye-transfer inhibitors, perfumes, bleaches, enzymes, fluorescers, optical brighteners, fungicides, germicides and hydrotropes.

Detergent Ingredients

Anionic surfactants which can be used in the compositions of the invention are both soap and non-scap detergents compounds. Especially suitable anionic detergent active compounds are water soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphur acid ester radicals and mixtures thereof.

Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to vield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

Suitable amphoteric detergent-active compounds that optionally can be employed are derivatives of aliphatic } secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilizing group, for instance sodium 3- dodecylamino-propionate, sodium 3-dodecylaminopropane

- 20 -~- sulphonate and sodium N-2-hydroxydodecyl-N-methyltaurate.

Suitable cationic detergent-active compounds are quaternary ammonium salts having an aliphatic radical of from 8 to 18 carbon atoms, for instance cetyltrimethyl ammonium bromide.

Suitable zwitterionic detergent-active compounds that optionally can be employed are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water- solubilising group, for instance 3-(N-N-dimethyl-N- hexadecylammonium), propane-l-sulphonate betaine, 3- (dodecylmethyl sulphonium) propane-l-sulphonate betaine and 3-(cetylmethylphosphonium) ethane sulphonate betaine.

Further examples of suitable detergent-active compounds are compounds commonly used as surface-active agents given in the well-known textbooks "Surface Active Agents", Volume I by Schwartz and Perry and "Surface Active Agents and

Detergents", Volume II by Schwartz, Perry and Berch.

The detergency builders which may be used in the formulation are preferably inorganic and suitable builders include alkali metal aluminosilicates (zeolites), alkali metal carbonate, sodium tripolyphosphate (STPP), tetrasodium pyrophosphate . (TSPP), citrates, sodium nitrilotriacetate (NTA) and combinations of these. Builders are preferably used in an : amount ranging from 1 to 50% by wt. Zeolite if used as builder is present at levels not exceeding 10% by wt.

The polymers of the invention are incorporated at the level of 0.001-10% by weight of the detergent composition, preferably 0.5-5% by weight of the detergent composition.

It is not always essential to incorporate the polymer of the invention in the detergent formulation. The polymers of the invention can be used as part of a fabric washing kit, as part of a sachet or can be microencapsulated.

The invention is illustrated further by the following non- limiting Examples.

EXAMPLES

Example 1

Preparation of Starch Phosphate 150 g of sodium tripolyphosphate (STPP) was dissolved in 260 ml of 2N HCl. The pH of the resultant solution was 4.

The resulting solution was sprayed on to 1 kg of starch and mixed well. The mixture was allowed to dry in air to a moisture content of 15%. The mixture was further dried in an oven to a moisture content of 10%. :

The phosphate content was estimated by colorimetry to be 1.53%.

A slurry of the polymer so obtained was made and the slurry was then drum dried to obtain the cold water soluble form of the polymer.

—_ 22 pu

This polymer could be converted to a phosphated, hydrophobic polysaccharide in accordance with the invention.

Example 2

Preparation of starch-graft-poly (methyl methacrylate) (Starch-g-MMA) 100 g urea was dissolved in 1 litre of distilled water in a flask equipped with a stirrer and a thermometer. 1 kg of tapioca starch, 1 g ferrous ammonium sulphate, 5 g ascorbic acid and 50 ml methyl methacrylate were added sequentially and the mixture was stirred. 10 ml hydrogen peroxide solution (30% w/v) was then added, the reaction mixture stirred and then filtered. The reaction was conducted at 30°C. The hydrophobic graft copolymer of starch-graft- poly (methyl methacrylate) obtained was repeatedly washed with water and then dried at 100°C.

Monomer conversion: 97%

Grafting efficiency: 93%

The monomer conversion refers to the total amount of the monomer that is converted into the polymer. The grafting efficiency refers to the total amount of polymer present as grafted side chains, the remaining being present as the homopolymer.

A slurry of the polymer so obtained was made and the slurry was then drum dried to obtain the cold water dispersible form of the polymer.

This polymer could be converted, by treatment with a phosphating agent, to a phosphated, hydrophobic polysaccharide in accordance with the invention (see Example 3 below).

Example 3

Preparation of starch phosphate-graft- poly (methyl methacrylate) (Starch-Phosphate-g-PMMA) 150 g of sodium tripolyphosphate (STPP) was dissolved in 260 ml of 2N HCl. The pH of the resultant solution was 4.

The resulting solution was sprayed on to 1 kg of the starch- graft-poly (methyl methacrylate) as prepared above and mixed well. The mixture was allowed to dry in air to a moisture content of 15%. The mixture was further dried in an oven to a moisture content of 10%. The phosphorus content was determined by colorimetry to be 1.5%.

A slurry of the polymer so obtained was made and the slurry was then drum dried to obtain the cold water soluble form of ) the polymer.

Example 4 :

Preparation of cationic starch phosphate-graft- poly (methyl methacrylate) (Cat Starch-Phosphate-g-PMMA)

A mixture of 73 g of a quaternary ammonium reagent, 1- chloro-2-hydroxy-trimethyl ammonium propyl chloride (QUAB 188 (Trade Mark), ex Degussa, 69% solids) and sodium hydroxide maintained at sub- ambient temperature was sprayed on to 100 g of the polymer prepared in Example 3. The product was then heated at about 90°C for 3 hours. The measured level of nitrogen was 0.117%.

Examples 5-7 and Comparative Examples A to D

Detergent Formulations

Detergent formulations of the invention and outside the invention were formulated.

A control detergent formulation without polymer was formulated (Comparative Example A). ) Detergent formulations incorporating starch phosphate and S- g-MMA were formulated (Comparative Examples B and C respectively).

Formulations incorporating the polymers of Example 3 and 4 were also prepared (Examples 5 and 6).

A Detergent formulation comprising K-SAM GE S00F (Trade Mark) (ex Kolon Chemical Co. Ltd., Korea) (Comparative Example D) and a formulation comprising a blend of the polymer of

Example 1 and K-SAM GE 500F (Trade Mark) (Example 7) were also prepared.

The formulation details are presented in Table 1.

‘ Table 1

I =

ETE DE DDE

Linear alkyl benzene : | 20 sulphonate rom rps | wm rom ces |e

Meee | w

CE IE

Ye 8 0) EN EA rena BEDEEED rr I I i

Sere) Io I I EE

Ee I el I 0 EE

CE — XC

Determination of Detergency Improvement

For determining detergency improvement, commercially available fabrics presoiled with a mixture of oily and particulate soil were used. WFK 30D was pre-soiled polyester, WFK 20D was presoiled polyester-cotton blend and

WFK 10D was pre-soiled cotton. The soil was a mixture of sebum and soot. The fabrics were obtained from Global

Resources Management Pvt. Ltd., Madras.

} Initial reflectance measurements of the fabrics were taken at 460 nm on a Milton Roy Color Scan II.

The fabrics (WFK 30D and WFK 10D) were cut into test swatches of 10 X 10 cm. and washed using the detergent compositions of

Example A (Control formulation) and Examples 3-8. Ten replicates were maintained for each example. Detergent solutions of concentration 5 g/l were used for the washing.

Test swatches were washed in a tergo-to-meter in the detergent solution for a period of 15 minutes. Reflectance measurements were taken at 460 nm for the washed pieces. The difference in reflectance of the soiled fabrics before and after washing was noted and represented as AR460*.

Improvement in detergency was determined as follows:

Improvement in detergency (AAR460*) = AR460* of the Example-

AR460* of Comparative Example A.

The results of the tergo-to-meter washes following the above detergency test procedure for removal of soil from WFK 30D, 20D and 10D is presented in Table 2.

Table 2

Detergency Improvement (AR460%*)

Example J wFK 30D | WFK20D WFK 10D

EE EE EE

CH CECH CR EC

CO CCH EN

CNN EH CO CN

CE EXCH CR CN

EA EXCH CE CO

The data presented in Table 2 shows that the formulation containing the polymer of the invention, starch phosphate-g-

PMMA (Example 5) shows superior detergency than a formulation containing starch phosphate (Comparative

Example B) or starch -g-PMMA (Comparative Example C).

Formulation containing the cationic starch phosphate -g -

PMMA (Example 6) shows good benefits on polyester and polyester blends. ) 15 Adding a cross-linked acrylic polymer, K-SAM GE 500F (Trade Mark), to the formulation (Example 7) gives a further : improvement in detergency, especially on polyester and polycotton.

' Example 8 and Comparative Examples E and F

Stiffness and Anti-wrinkling Benefits of Starch Phosphate-g-

PMMA

The polymers of the invention were evaluated for benefits when used as rinse conditioners. Cotton and poly-cotton were used in the study. A panel of 28 members evaluated the polymer for stiffness and good ironing (anti-wrinkling benefit) in a paired comparison test.

Prior to the study, the fabrics were desized by washing with a detergent. The detergent concentration was 3 g/litre.

Fabrics were then washed with the polymer of Example 3. An aqueous solution of the polymer (5g/litre) was used as the rinse conditioner (Example 8). A commercially available cold water soluble starch (5g/litre) was also evaluated in the study (Comparative Example E).

Example 8 was compared with Comparative Example E and an untreated control fabric washed with water (Comparative

Example F). The fabrics were dried after the treatment and ironed.

The stiffness and ironing benefit, ascertained visually, were assessed in a paired comparison test. The data are presented in Table 3 and Table 4.

Table 3

Attribute | No. of respondents giving a high | Statistical rank (out of a total of 28) Significance \

Example 8 Comparative :

Example E

Stiffness 16 12 Not significant 1 . .

Table 4

Attribute No. of respondents giving a high | Statistical rank (out of a total of 28) Significance

Example 8 Comparative

Example F fronting Benetit

A statistical significance of 95% and above indicate that the product is clearly perceived by the panel to be superior. When the statistical significance is indicated as not significant it means that there is no particular preference for a product.

- 31 =~ ' Table 3 shows that the polymer of the invention provides superior ironing benefits as compared to a commercial starch without compromising on stiffness.

Table 4 shows that the polymer of the invention, starch phosphate-g-PMMA is clearly superior in stiffness and ironing benefits as compared to a control.

Claims

' 1. Phosphated, hydrophobic polysaccharide which is a graft copolymer of a polysaccharide having phosphate substituents with an ethylenically unsaturated monomer, characterised in that the copolymer has a polysaccharide backbone carrying grafted hydrophobic vinyl polymeric groups derived from the ethylenically unsaturated monomer, and phosphate substituents.
2. Phosphated, hydrophobic polysaccharide according to claim 1, characterised in that it has the general formula I: i A R wherein R is a hydrophobic vinyl polymer, R' represents a phosphate group or its salt and G is a monosaccharide or substituted monosaccharide.
3. Phosphated, hydrophobic polysaccharide according to claim 2, characterised in that R’ has the general . formula II: RK? Xi Xo wherein each of Xi and X», which may be the same or different, is selected from ONa, OH, Cl or OG where G is another polysaccharide backbone thereby providing a cross-linked polymer.
4. Phosphated, hydrophobic polysaccharide according to claim 2, characterised in that R’ has the general formula III: —O0——P—Y, / IN Y4 Ys Y2 wherein each of Y;, Ys, ¥Y3 and Y4, which may be the same or different, is selected from Cl or OG where G is another polysaccharide backbone thereby providing a cross-linked polymer.
5. Phosphated, hydrophobic polysaccharide according to any one of claims 2 to 4, characterised in that R’ is obtained by reaction of the polysaccharide with a phosphating agent selected from phosphoric acid, sodium tripolyphosphate (STPP), tetrasodium phosphate, phosphorus pentachloride, phosphoryl chloride, sodium trimetaphosphate, polymeric sodium orthophosphates and mixtures thereof, preferably STPP.
6. Phosphated, hydrophobic polysaccharide according to any preceding claim, characterised in that the ratio by weight of the polysaccharide to the phosphate substituent is from 1:1 to 1:0.001, preferably from

1:0.5 to 1:0.01, more preferably from 1:0.3 to 1:0.1.
7. Phosphated, hydrophobic polysaccharide according to any preceding claim, characterised in that the polysaccharide is selected from starch, modified starches, cellulose, guar gum, and tamarind gum, preferably starch.
8. Phosphated, hydrophobic polysaccharide according to any one of claims 2 to 7, characterised in that the

. hydrophobic vinyl polymer has a molecular weight from 500 to 5,000,000, preferably from 2000 to 500,000, more preferably from 5000 to 100,000.