GB2375356A

GB2375356A - Cationic fabric softening compositions

Info

Publication number: GB2375356A
Application number: GB0111542A
Authority: GB
Inventors: Francesca Rosiello; Anthony Sidoti; Roberto Vanin
Original assignee: Reckitt Benckiser NV
Current assignee: Reckitt Benckiser NV
Priority date: 2001-05-11
Filing date: 2001-05-11
Publication date: 2002-11-13
Also published as: WO2002092742A1; EP1392806B1; DE60207854D1; ES2249571T3; EP1392806A1; ATE312154T1; DE60207854T2; GB0111542D0

Abstract

Fabric softening compositions comprise 3-20 wt. % a cationic fabric softener, 1-10 wt. % a fabric co-softener and at least 1 wt. % a hydrotrope. They are of medium viscosity, transparent and free from organic solvents and show good softening performance.

Description

Fabric Softening Composition The present invention relates to fabric softening compositions, particularly transparent conditioners.

Fabric softening compositions are known in the art for imparting benefits such as softness and/or antistatic properties to the treated fabric. However, nowadays, consumer acceptance of fabric softening compositions is determined not only by the performance achieved with these products but also by the aesthetics associated therewith. Viscosity of the product is therefore an important aspect of the successful formulation of such commercial products, stable low to medium viscosities being highly preferred by consumers. By medium viscosities, it is meant viscosities of 0.5cps to 5000 cps, preferably 200 to 2,000.

To fulfil such need, fatty acids have been incorporated into fabric softening compositions. Such a disclosure can be found in the pending Application EP 95870104.7.

Accordingly, it is an object of the invention to provide a softening composition with medium viscosity. It is a further feature of the invention that preferably the softening composition is transparent.

The Applicant has now found that the provision of specific cationic surfactants in combination with certain co-softening cationic surfactants produces fabric conditioners of medium viscosity which are transparent, free from organic solvents and perform well on softening fabrics.

Certain formulations show low sensitivity to shear, particularly by inclusion of a small amount of a nonionic surfactant.

By"low sensitivity to shear", it is meant that the viscosity of the initially produced product stays close to its initial value over time. In other words, the fabric softening composition displays Newtonian rheology characteristics.

Certain mono C6-22 alkyl, or alkenyl, quaternerised amines are well known in the art for use in producing fabric conditioners without the need for solvents to produce a transparent composition. However, such amines have weaker fabric softening properties compared with di, tri C6-22 alkyl, or alkenyl quaternerised amines.

We have found that certain fabric co-softeners can be added which still make transparent compositions but which give improved fabric softening properties. Medium viscosity liquids are produced, preferably which have low sensitivity to shear, by the addition of specific preferred thickeners. The performance of these fabric softening compositions is not compromised by higher viscosities, being highly dispersible without the normal hydration gelling that can occur with more viscous surfactant systems. The softening profile is as good as, if not even better then that from traditional systems.

The present invention is a fabric softening composition comprising: a) a cationic fabric softener in an amount of 3 % to 20 % by weight, b) 1 % to 10 % by weight of a fabric co-softener

c) 0% to 5% by weight of a hydrotrope, preferably 0.1% to 2. 5% by weight.

In another aspect of the invention, there is provided a method for treating fabrics which comprises the step of contacting said fabrics in the rinse cycle with an aqueous medium containing said composition.

Cationic fabric softener A cationic fabric softener is an essential ingredient of the invention. Typical levels of said fabric softener components within the softening compositions are 3 % to

20 % by weight, preferably from 4 % to 15 % by weight, and more preferably from 4 % to 10 % by weight of the composition.

The preferred, typical cationic fabric softening components include the water-dispersable quaternaryammonium fabric softeners. Preferred cationic softeners include the following: quaternary ammonium compounds and amine precursors herein have the formula (I), below:

wherein Q is selected from-CH2-,-O-C (O)-,-C- (0)-0- and -0-C (0)-0- (preferably-CH2-) ;

R1, R2 and R3 are independently selected from Cl-C4 alkyl or C1-C4 hydroxyalkyl or H (typically methyl); Tl is C6-C22 alkyl or alkenyl (typically alkyl) ; n is an integer from 1 to 4 (preferably n is 2); and X- is a softener-compatible anion.

Non-limiting examples of softener-compatible anions include chloride or methyl sulfate, preferably chloride.

The alkyl, or alkenyl, chain T1 must contain at least 10 carbon atoms, preferably at least 14 carbon atoms, more preferably at least 16 carbon atoms. The chain may be straight or branched.

Conventionally T1 may be tallow, especially hydrogenated tallow.

Specific examples of quaternary ammonium compounds suitable for use in the aqueous fabric softening compositions herein include: hydrogenated tallow trimethyl ammonium X, wherein X- is preferably chloride.

The level of unsaturation of the chain can be measured by the Iodine Value (IV) of the corresponding fatty acid, which in the present case should preferably be in the range of from 5 to 100 with two categories of compounds being distinguished, having a IV below or above 25.

In fact, the anion is merely present as a counterion of the positively charged quaternary ammonium compounds. The nature of the counterion is not critical at all to the practice of the present invention. The scope of this invention is not considered limited to any particular anion. By"amine precursors thereof"is meant the secondary or tertiary amines corresponding to the above

quaternary ammonium compounds, said amines being substantially protonated in the present compositions due to the pH values.

For the preceding fabric softening agents, especially with biodegradable fabric softening agents, the pH of the liquid compositions herein is a preferred parameter of the present invention. Indeed, it influences the stability of the quaternary ammonium or amine precursors compounds, especially in prolonged storage conditions.

The pH, as defined in the present context, is measured in the neat compositions at 20 C. For optimum hydrolytic stability of these compositions, the neat pH, measured in the above-mentioned conditions, must be in the range of from 2 to 5. The pH of these compositions herein can be regulated by the addition of a Bronsted acid.

Examples of suitable acids include the inorganic mineral acids, carboxylic acids, in particular the low molecular weight (Cl-C5) carboxylic acids, and alkylsulfonic acids.

Suitable inorganic acids include HCl, H2S04, HN03 and H3P04. Suitable organic acids include formic, acetic, citric, methylsulfonic and ethylsulfonic acid. Preferred acids are citric, hydrochloric, phosphoric, formic, methylsulfonic acid, and benzoic acids. Especially preferred is citric acid.

The softening composition of the invention will also comprise a liquid carrier. Suitable liquid carriers are selected from water, organic solvents and mixtures thereof. The liquid carrier employed in the instant compositions is preferably at least primarily water due to its low cost relative availability, safety, and environmental compatibility. The level of water in the liquid is preferably at least 80 %, most preferably at least 90 %, by weight of the carrier. Preferably the

liquid carrier is at least 20 %, most preferably at least 30 %, by weight of the composition. Mixtures of water and low molecular weight, e. g. , < 200, organic solvent, e. g., lower alcohol such as ethanol, propanol, iso-propanol or butanol are useful as the carrier liquid. Low molecular weight alcohols include monohydric, dihydric (glycol, etc. ) trihydric (glycerol, etc. ), and higher polyhydric (polyols) alcohols could also be used.

Hydrotrope Use of hydrotropes usually aid in the solubility or dispersability of different surfactants in aqueous solution. This usually has the side effect of lowering the viscosity of the resulting mixture. Surprisingly, we have found that the use of a small amount of hydrotrope in our compositions causes a viscosity increase. Whilst not being bound by theory we believe this is likely due to the complex formed between the anionic hydrotrope salt and the cationic surfactant. The complex is soluble and clear in solution and provides a viscosity increasing matrix.

Examples of suitable and preferred hydrotropes are the alkali metal salts of cumene and xylene sulfonate, ideally the sodium salt.

Fabric Co-softener Among the suitable co-softeners are amines of formula (II)

at least one, and preferably no more than two, of R3, R4 and R are C16-22 alkyl or alkenyl (preferably alkenyl), preferably C17-19 ideally C, 8 ; and the remaining group (s), if any, are CI-4 hydroxyalkyl or hydrogen, preferably Ci-4 hydroxyalkyl, ideally hydroxyethyl. A preferred compound is oleylbis (2-hydroxyethyl) amine.

Other co-softeners include, but are not limited to; amine oxides, betaines and alkali metal soaps. The preferred fatty acid precursors contain a high proportion of unsaturation, with oleyl groups being the most preferred.

Optional The composition may also contain optional components which may be suitable for further improving the aesthetic appearance of the fabrics treated therewith. Suitable optional components include polyethylene glycols, additional fabric softening components, enzymes, cyclodextrin/perfume complexes and free perfume delivery systems, and mixtures thereof, preferably in the form of an alkali metal salt, ideally sodium.

Polyethylene glycol A polymeric material which can optionally be included is polyethylene glycol (PEG). When used, PEG may provide an increase in the viscosity stability upon storage of the composition of the invention. Typical molecular weight ranges for these purposes range from 500 to 100,000. preferably from 1,000 to 50,000, more preferably from 1,500 to 10,000. A most preferred molecular weight is 4,000. When present, typical levels of polyethylene glycols are from 0.01 to 1 % by weight, preferably from 0.05 % to 0.5 % by weight of the composition.

Additional Components The composition may also optionally contain additional components such as surfactant concentration aids, electrolyte concentration aids, stabilisers, such as well known antioxidants and reductive agents, emulsifiers, bacteriocides, colorants, perfumes, preservatives, optical brighteners, anti ionisation agents, chelants, natural and synthetic extracts and antifoam agents.

Stabilisers Stabilisers may also optionally be added. When used, said stabiliser will help achieving the desired finished product viscosity as well as stabilising the finished product upon storage. Stabilisers are typically selected from single long chain alkyl cationic surfactants, nonionic alkoxylated surfactants, amine oxides, fatty acids, and mixtures thereof, typically used at a level of from 0 to 15 % by weight of the composition.

Electrolyte Stabilisers Inorganic viscosity control agents which can also act like or augment the effect of the stabilisers, include water-soluble, ionisable salts which can also optionally be incorporated into the compositions of the present invention. Incorporation of these components to the composition must be processed at a very slow rate.

A wide variety of ionisable salts can be used. Examples of suitable salts are the halides of the Group IA and IIA metals of the Periodic Table of the Elements, e. g., calcium chloride, magnesium chloride, sodium chloride, potassium bromide, and lithium chloride. The ionisable salts are particularly useful during the process of mixing the ingredients to make the compositions herein, and later to obtain the desired viscosity. The amount of ionisable salts used depends on the amount of active ingredients used in the compositions and can be adjusted according to the desires of the formulator. Typical levels of salts used to control the composition viscosity are from 20 to 2000 parts per million (ppm), preferably from 20 to 1100 ppm, by weight of the composition.

Alkylene polyammonium salts can be incorporated into the composition to give viscosity control in addition to or in place of the water-soluble, ionisable salts above. In addition, these agents can act as scavengers, forming ion pairs with anionic detergent carried over from the main wash, in the rinse, and on the fabrics, and may improve softness performance. These agents may stabilise the viscosity over a broader range of temperature, especially

at low temperatures, compared to the inorganic electrolytes.

Specific examples of alkylene polyammonium salts include 1-lysine monohydrochloride and 1,5-diammonium 2-methyl pentane dihydrochloride. The present invention also encompasses a method for treating fabrics which comprises the step of contacting said fabrics in the rinse cycle with an aqueous medium containing a composition as defined hereinbefore. Preferably, the aqueous medium is at a temperature between 2 to 40 C, preferably between 5 to 25 C.

The invention is illustrated in the following non limiting examples, in which all percentages are on an active weight % basis unless otherwise stated.

SOFTNESS IMPROVEMENT The use of a cationic surfactant of formula (I) usually gives a relatively low performance compared with standard ditallow Esterquat.

We have tested the softness performance of formulations with monoalkyl cationic versus a standard, commercially available fabric softening composition based on ditallow Esterquat.

Terry cloths were washed with the different Fabric Softeners, then, when dry, were judged by a group of panelists.

The panelists were asked to assign a number from 0 (very harsh) to 7 (very soft) to the test swatches.

Products tested and results:

ACTIVE MATTER Product A Product B Product C Commercial Softener monoalkyl cationic (alkyl 3 % 3 % 3 %/ trimethyl ammonium chloride) Cocoamidepropyl betaine 3 Alkyl dimethyl amine oxide/2. 1%// Oleylbis (2-hydroxyethyl) amine//1. 85%/ Ditallow Esterquat///5. 4% DOSE/Washing 68 ml 68 ml 68 ml 84 ml Cationic/washing 2. 04 ml 2.04 ml 2. 04 ml 4.536 AVERAGE SCORE 2. 5 3. 1 4. 2 4. 8 As is plainly evident, 1,85 % of an amine fabric cosoftener of formula (II) greatly increases the softness performance of a monoalkyl cationic fabric softener.

VISCOSITY IMPROVEMENT To increase the viscosity of the formulation, and, at the same time, maintain the clarity of the product is very difficult.

The following chart lists the thickeners evaluated:

THICKENERS % VISCOSITY DRAWBACKS Cps Brookfield LVT1 12 rpms Rohagit KF720 - Polyelectrolyte 0.5 125 Hard to Cationic based on Methacrylammide dissolve Rohagit KL280-Acrylic Polymer0. 5 10 Yellow 2.5 42 Orange Acusol 882-polyethylene glycol 0.5 2 modified 2.5 4.5 Acusol 884-starch modified 0. 5 10 Opaque Xanthan Gum (various MW) 0. 02/Insoluble 0. 5 I Cocoamidopropyl betaine 1. 2 24 PVP-Polyvinyl pyrrolidone 1 3 Yellow Polyflos SA 4W - Hydroxyalkyl 0.3 115 Hard to polygalattomannane dissolve Carbopol - Polyacrylic Acid Polygel K100-Cationic Plymer 0.5 15 opaque

There are two Polymers that give increased viscosities: Rohagit KF720 and Polyflos SA 4W. Unfortunately, they are very expensive and require great effort and time to dissolve in the formulations.

We have found that the addition of a hydrotope, such as Sodium Cumene Sulphonate (SCS) and Sodium Xylene Sulphonate (SXS), can be used as thickeners: Sodium cumene sulphonate (active 40%) at a 2% level increase the viscosity of the formulation from 10 cps to 500-700 cps.

RAW MATERIALS Reference Sample 1 Sample 2 Sample 3 Sample 4 Quartamin THL (alkyl 6 6 6 6 6 trimethyl ammonium chloride-50% active) Perfume 0. 95 0. 95 0. 95 0. 95 0. 95 Eltesol SCS- (40% Na/1 1. 5 2/ Cumene Sulphonate) Eltesol SXS- (40% Na////2 Xylene Sulphonate) Water balance Balance balance balance Balance Viscosity (LVT1 6) rpm 15 18 12 500 200 APPEARANCE CLEAR CLEAR CLEAR CLEAR CLEAR Additional examples include:

Trade Name Raw Material Sample 5 Sample Sample description 6 7 Quartamin THL (alkyl trimethyl ammonium chloride Softener Active 6 6 6 - 50% active) Ethomeen S712 (Dioleyl amine) Co-softener 1. 8 1. 8 1. 8 Eltesol SC40 (Na cumene sulfonate-40% active) Hydrotrope 2 2. 5 3. 0 Perfume Fragrance 0. 95 0. 95 0.95 Citric acid PH adjuster 0. 6 0. 6 0. 6 Preservative BIT Preservative 0. 05 0. 05 0. 05 Natural Extracts 0. 025 0. 025 0.025 Water Viscosity (LVT1) 6 rpm 600 cps 700 300 Appearance CLEAR CLEAR OPAQUE

As can be seen, increasing the hydrotrope level above 2.5% results in decreased viscosity and opacity, both undesirable features of the present invention.

Claims

Claims 1. A fabric softening composition comprising: a) a cationic fabric softener in an amount of 3 % to 20 % by weight, b) 1 % to 10 % by weight of a fabric co-softener c) at least 1% by weight of a hydrotrope.
2. A fabric softening composition as claimed in claim 1 wherein the cationic fabric softener is 4 % to 10 % by weight of the composition.
3. A fabric softening composition as claimed in claim 1 or 2 wherein quaternary ammonium compounds and amine precursors herein have the formula (I), below:

wherein Q is selected from-CH2-,-O-C (O)-,-C- (0)-0- and - 0-C (0)-0- (preferably-CH2-) ; 1 2 3 R1, R2 and R3 are independently selected from C1-C4 alkyl or C1-C4 hydroxyalkyl or H (preferably methyl); T1 is C6-C22 alkyl or alkenyl (preferably alkyl) ; n is an integer from 1 to 4 (preferably n is 2); and X- is a softener-compatible anion.

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4. A fabric softening composition as claimed in claim 3 wherein the softener-compatible anion X- is chloride or methyl sulfate, preferably chloride.
5. A fabric softening composition as claimed in any claim from 1 to 4 wherein the alkyl or alkenyl chain T1 must contain at least 10 carbon atoms, preferably at least 14 carbon atoms, more preferably at least 16 carbon atoms.
6. A fabric softening composition as claimed in any claim from 1 to 5 wherein the hydrotrope is cumene sulphonate or xylene sulphonate, preferably in the form of an alkali metal salt, ideally sodium and at a level of 0-5%, preferably 2%.
7. A fabric softening composition as claimed in any claim from 1 to 6.
8. A fabric softening composition as claimed in any claim from 1 to 6 wherein the fabric co-softener is a compound of formula (II)
9. at least one, and preferably no more than two, of R3, R4 and R5 are C16-22 alkyl or alkenyl (preferably alkenyl), preferably C17-I9 ideally CIs ; and the

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remaining group (s), if any, are Cl-4 hydroxyalkyl or hydrogen, preferably Cl-4 hydroxyalkyl, ideally hydroxyethyl.
10. A fabric softening composition as claimed in claim 8 wherein the fabric co-softener is oleylbis (2- hydroxyethyl) amine.
11. A method for treating fabrics which comprises the step of contacting said fabrics in the rinse cycle with an aqueous medium containing said composition.