WO2002092742A1

WO2002092742A1 - Fabric softening composition

Info

Publication number: WO2002092742A1
Application number: PCT/GB2002/002166
Authority: WO
Inventors: Francesca Rosiello; Anthony Sidoti; Roberto Vanin
Original assignee: Reckitt Benckiser N.V.; Reckitt Benckiser (Uk) Limited
Priority date: 2001-05-11
Filing date: 2002-05-10
Publication date: 2002-11-21
Also published as: EP1392806B1; DE60207854D1; ES2249571T3; GB2375356A; EP1392806A1; ATE312154T1; DE60207854T2; GB0111542D0

Abstract

The present invention relates to fabric softening compositions, preferably translucent, clear or transparent conditioners, which in addition to a cationic fabric softener comprise a fabric co-softener, and a hydrotope.

Description

Fabric Softening Composition

The present invention relates to fabric softening compositions, preferably translucent, clear or transparent conditioners, which in addition to a cationic fabric softener comprise a fabric co-softener, and a hydrotope .

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.

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.

Clear fabric softeners are usually achieved through the use of high concentrations of organic solvents. Viscous solutions are usually prepared by the addition of gelling/thickening agent. However we have found that certain clear compositions can be produced without the use of organic solvents, without the need to add a thickening/gelling system. The reduction or elimination of a thickening/gelling system will reduce the cost of the formulation. In addition the organic solvents used to produce clear fabric softening compositions have a negative odour.

Accordingly, it is an object of the invention to provide a softening composition with a medium viscosity, able to provide fabric softening, static control, water dispersibility, rewettability and aesthetic fragrance benefits. It is a further feature of the invention that, preferably, the softening composition is clear.

Clear fabric softener compositions containing high levels of organic solvent are well know in the art as described on Patents WO 96/19552 or WO 01/02522 or WO 96/09365 or US 5656585 or WO 99/09122 or US 5747443.

A person skilled in the art can produce clear fabric softener compositions by the combination of quaternary ammonium compound with organic solvents. These compositions generally have high organic solvent concentrations which are needed to provide clarity, but have a high negative odour and, usually, poor softening performance .

Furthermore these compositions have a low viscosity in the absence of a thickening/gelling system.

Aqueous viscous cleaning compositions including: a) inorganic or organic acid, b) a cationic detergent, c) a water insoluble or partially soluble covalent compound such us an ester of an inorganic acid, a fatty acid or an ester of a fatty acid, a carboxylic acid ester or amine- oxide and d) anionic sulfonate, are described on Patents GB 1240469 or EP 0 265 979.

Clear single phase fabric softeners comprising an anionic surfactant having an alkyl radical containing at least eight carbon atoms, a cationic surfactant and an effective amount of propylene glycol and an alkali metal salt of benzene, toluene or xylene sulfonate are described in US 4751009.

The present invention is based on the surprising discovery that it is possible to obtain a stable clear medium viscosity fabric softener that performs well on softening fabrics, which comprises a cationic surfactant, a co-softening agent and a hydrotope, such as an alkali metal salt of a benzene, cumene, toluene or xylene sulfonate.

By medium viscosity, it is meant a viscosity of 50 cps to 5000 cps, preferably 200 to 2,000 cps, as measured on a Brookfield LV, spindle 2, 12 rpm and at 20°C.

The performance of these fabric softening compositions is not compromised by their higher viscosity, they are highly dispersible into water without the normal hydration gelling that can occur with some viscous surfactant systems. The softening performance is as good as, if not better than, 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 hydrotropej preferably 0.1% to 2.5% by weight.

In another aspect of the invention, there is provided a method of treating fabric which comprises the step of contacting said fabric in the rinse cycle of a fabric washing machine with an aqueous medium containing a composition as defined herein.

Cationic fabric softener

A cationic fabric softener is an essential ingredient of the invention. Typical levels of the cationic fabric softener 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 cationic fabric softening components include the water-dispersible quaternary ammonium fabric softeners or an amine precursor thereof. Preferred quaternary ammonium compounds herein are of formula (I) :

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

-0-C(0)-0- (preferably -CH₂-) ;

R¹, R² and R³ are independently selected from Cι-C₄ alkyl or Cι-C₄ hydroxyalkyl or H (typically methyl) ;

T¹ is C₆-C₂₂ alkyl or alkenyl (typically alkyl) ; n is an integer from 0 to 4 (preferably n is 2) ; and

X^" is a softener-compatible anion.

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

The alkyl, or alkenyl, chain TI should contain at least 5 carbon atoms, preferably at least 13 carbon atoms, more preferably at least 15 carbon atoms . The chain may be straight or branched.

A specific example of a quaternary ammonium compound suitable for use in the aqueous fabric softening compositions herein is 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.

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 precursor thereof" it is meant the secondary or tertiary amine 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, the pH 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, is ideally 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 (Cι-C₅) carboxylic acids, and alkylsulfonic acids. Suitable inorganic acids include HCl , H₂S0₄, HN0₃ and H₃PO₄. 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, 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

(by "low molecular weight" we mean less than 200) organic solvent may be used. Preferred low molecular weight organic solvents are; monohydric alcohol, such as ethanol , propanol, iso-propanol or butanol ; dihydric alcohol, such as glycol; trihydric alcohols, such as glycerol, and polyhydric (polyol) alcohols.

Hydrotrope

Hydrotropes aid in the solubility or dispersibility 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 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 a benzene, cumene, toluene and xylene sulfonate, ideally the sodium salt. Fabric Co-softener

Fabric co-softeners are understood by the skilled person as non-quarternary hydrophilic compounds which are added to boost softening performance .

Among the suitable co-softeners are amines of formula (ID R³ R⁴

\ / N

(ID

R³

at least one, and preferably no more than two, of R³, R⁴ and R⁵ are Cι_6-22 alkyl or alkenyl (preferably alkenyl) , preferably C17-1₉ ideally Cχ₈; and the remaining group (s), if any, are Cι_-4 hydroxyalkyl or hydrogen, preferably Cι_-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, example include, but are not limited by, surfactant concentration aids, electrolyte concentration aids, 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, non- ionic 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

As is plainly evident, 1,85 % of an amine fabric co- softener 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:

There are two Polymers that give increased viscosities: Rohagit KF720 and Polyflos SA 4W. Unfortunately, they have disadvantage of being very expensive and are difficult to dissolve in the formulations.

We have found that the addition of a hydrotrope, 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 increases the viscosity of the formulation from 10 cps to 500-700 cps.

Additional examples include

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

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 hydrotrope

A fabric softening composition as claimed in claim 1 wherein the cationic fabric softener is 4 % to 10 % by weight of the composition.

A fabric softening composition as claimed in claim 1 or 2 wherein the cationic fabric softener is quaternary ammonium compounds having the formula (I), below:

wherein Q is selected from -CH₂-, -0-C(0)-, -C- (0) -

0- and -0-C(0)-0- (preferably -CH₂-);

R¹, R² and R³ are independently selected from Cι-C₄ alkyl or Cι-C₄ hydroxyalkyl or H (preferably methyl) ;

T¹ is C₆-C₂₂ alkyl or alkenyl (preferably alkyl ) ; n is an integer from 0 to 4 (preferably n is 2) ; and

X^" is a softener-compatible anion.

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 claim 3 and 4 wherein the alkyl or alkenyl chain TI should contain at least 5 carbon atoms, preferably at least 13 carbon atoms, more preferably at least 15 carbon atoms .

6. A fabric softening composition as claimed in any claim from 1 to 5 wherein the hydrotrope is a benzene sulfonate, cumene sulfonate, toluene sulfonate or xylene sulfonate, in the form of an alkali metal salt, ideally sodium.

7. A fabric softening composition as claimed in any claim from 1 to 6 wherein the hydrotrope is at a level of 0.1 to 2.5%w/v.

A fabric softening composition as claimed in any claim from 1 to 6 wherein the fabric co-softener is a compound of formula (II)

R^J R⁴

\ /

N

(ID

R⁵

at least one, and preferably no more than two, of R³, R⁴ and R⁵ are Cι_6-22 alkyl or alkenyl (preferably alkenyl) , preferably Cι_7-ι₉ ideally Cι₈; and the remaining group (s), if any, are Cι_-4 hydroxyalkyl or hydrogen, preferably Cι_-4 hydroxyalkyl , ideally hydroxyethyl .

9. A fabric softening composition as claimed in claim 8 wherein the fabric co-softener is oleylbis(2- hydroxyethyl ) amine .

10. A method of treating fabric which comprises the step of contacting the fabric in the rinse cycle of a fabric washing machine with an aqueous medium containing a fabric softening composition as defined in any claim from 1 to 9.