DE69625243T2 - FABRIC SOFTENING COMPOSITION - Google Patents

Description

Field of the invention

The present invention relates to a fabric softening composition, in particular the invention relates to aqueous dispersions of fabric softening compositions comprising a water-insoluble quaternary ammonium material and a non-ionic stabilizing agent, which are suitable as rinse-added fabric softening compositions.

Background of the invention

Rinse-added fabric softeners are known. Typically, such compositions contain a water-insoluble quaternary ammonium fabric softener dispersed in water at a level of softening agent of up to about 7% by weight, in which case the compositions are considered dilute, or at levels of from 7% to 50% by weight, in which case the compositions are known as concentrates.

The viscosity of fabric softeners can be seen by the consumer as an important property. For this reason, thickening polymers are added to the compositions, for example EP 0 331 237 (Unilever) discloses the use of hydrophobically modified non-ionic cellulose ether for use as a thickener for fabric conditioning compositions containing quaternary ammonium cations.

Many polymer thickeners have the negative attribute that they are not biodegradable, their addition to the product to be rinsed is technically is difficult and the viscosity of such thickened polymer products usually increases over time.

WO 97/08285 discloses fabric softening compositions based on a mixture of a tertiary amine and a quaternary diester fabric softener, wherein at least about 20% of the hydrocarbon substituent groups present in the tertiary amine and the quaternary diester fabric softener are unsaturated.

WO 97/12952 discloses a detergent composition comprising an amphoteric and/or a non-ionic surfactant together with a substantially water-insoluble fabric softening compound and a detergency enhancer. The amphoteric non-ionic surfactant solubilizes the fabric softening compound.

In US 4 137 180 (Lever Brothers Company) cationic diesters of the formula

wherein R₁, R₂ and R₃ each represent an alkyl or hydroxyalkyl group having 1 to 4 carbon atoms, or a benzyl group, R₁ and R₅ each represent alkyl chains having 11 to 23 carbon atoms, and X⁻ represents a water-soluble anion.

One of the problems associated with fabric softening compositions containing cationic diesters as disclosed in US 4,137,180 is the physical instability of these compounds, which problem is exacerbated at temperatures above or below ambient.

EP 280 550 and EP 507 478 (Unilever) disclose the use of selected non-ionic stabilizing agents to overcome the poor stability. However, we have found that many non-ionic stabilizing agents create a further problem in that their presence creates the viscosity of these fabric softening compositions.

EP 409 504 (Unilever) discloses fabric softening compositions comprising at least 1% w/w of an ester-linked quaternary and an extruder material which may be esters of predominantly linear C8-C28 fatty acids with polyhydric alcohols.

WO 95/27777 discloses rinse conditioners comprising a fabric softening compound and a solubilizing agent applied to a tumble dryer sheet.

We have now found that selected non-ionic stabilizing agents do not destroy the viscosity of fabric softening compositions containing a biodegradable quaternary ammonium material.

Description of the invention

Accordingly, the present invention relates to a fabric softening composition comprising:

a) an aqueous dispersion of a water-insoluble quaternary ammonium material comprising at least one ester bond and two C₁₂₋₂₈ alkyl or alkenyl groups;

b) 0.1% to 2.5% by weight of the total composition of a non-ionic stabilising agent which is a sucrose ester,

wherein the sucrose ester is a mixture of a monoester, diester and a triester, and 56 to 75 weight percent, based on the total weight of sucrose ester, is a sucrose monoester.

Furthermore, a method for producing a liquid fabric softening composition is disclosed, comprising the steps of selecting the following ingredients:

a) a water-insoluble quaternary ammonium material comprising at least one ester bond and two C₁₂₋₂₈ alkyl groups;

b) a non-ionic stabilizing agent which is a mixture of sucrose monoester, sucrose diester and sucrose triester, wherein 56 to 75 percent by weight of the total weight of sucrose ester is a sucrose monoester;

c) other optional components;

then mixing the ingredients with heating to form a melt, followed by dispersing the melt in water to form an aqueous dispersion of the water-insoluble quaternary ammonium material containing from 0.1% to 2.5% by weight based on the total composition of the non-ionic stabilizing agent.

Description of the invention in detail

The present invention is a way to control the viscosity of a fabric conditioning composition containing a biodegradable quaternary ammonium material and a non-ionic stabilizing agent.

Without wishing to be bound by theory, it is believed that the action of the invention occurs essentially through the interaction of the hydrogen bonding elements of the non-ionic stabilizing agent molecules while maintaining the vesicle structure. A vesicle structure in the context of this invention can be defined as a spherical structure with onion-ring bilayers. The presence of such vesicle structures is an important factor in the formation of a composition with a commercially acceptable viscosity.

The preferred amount of the non-ionic stabilizing agent present is 0.1 to 2.5 weight percent.

Particularly preferred non-ionic stabilizing agents are the sucrose esters. The sucrose esters have the additional advantage of imparting additional softening benefits over the cationic softening agent. Examples of suitable sucrose esters include the Crodesta (Trademark (of Croda)) range. Crodestas are sucrose esters esterified with 70/30 mixture of stearic/palmitic acid to form a mixture of monoester, diester and triester. According to the manufacturers, the proportions of monoester are as follows:

Trade name Weight percent Monoester

Crodesta F10 3

Crodesta F20 10

Crodesta F50 29

Crodesta F70 56

Crodesta F110 52

Crodesta F140 57

Crodesta F160 75

We have found that this combination of monoesters and diesters and triesters of sucrose give particularly good softening benefits. Particularly preferred are combinations of monoester, diester and triester containing 56-75% monoester, particularly Crodesta F160, Crodesta F140, Crodesta 110 and Crodesta F70.

The fabric softening compound is suitably a substantially water-insoluble quaternary ammonium material comprising a polar head group and two alkyl or alkenyl chains each having an average chain length greater than or equal to C₁₄ and at least one ester group.

Preferably, the fabric softening compound of the invention has two long chain alkyl or alkenyl chains each having an average chain length greater than or equal to C16. More preferably, at least 50% of each long chain alkyl or alkenyl group has a chain of C18.

It is preferred if the long-chain alkyl or alkenyl groups of the fabric softening compound are predominantly linear.

The fabric softening compounds used in the compositions of the present invention are molecules that provide excellent softening and are characterized by a chain melting Lβ to Lα transition temperature of greater than 25°C, preferably greater than 35°C, most preferably greater than 45°C. This Lβ to Lα transition can be measured by DSC as defined in "Handbook of Lipod Bilayers", D Marsh, CRS Press, Boca Raton Florida, 1990 (pages 137 and 337).

Substantially insoluble fabric softening compounds in the context of this invention are defined as fabric softening compounds having a solubility of less than 1 x 10-3 wt% in demineralized water at 20°C. Preferably, the fabric softening compounds have a solubility of less than 1 x 10-4. More preferably, the fabric softening compounds have a solubility at 20°C in demineralized water of 1 x 10-8 to 1 x 10-6.

It is particularly preferred when the fabric softening compound is a water-insoluble quaternary ammonium material comprising a compound having two C₁₂₋₁₈ alkyl or alkenyl groups attached to the molecule via at least one ester linkage. It is more preferred when the quaternary ammonium material has two ester linkages present. A particularly preferred ester-linked quaternary ammonium material for use in the invention can be represented by the formula:

wherein each R¹ group is independently selected from C₁₋₄alkyl, hydroxyalkyl or C₂₋₄alkenyl groups; and wherein each R² group is independently selected from C₈₋₂₈alkyl or alkenyl groups; X⁻ represents a suitable anion.

T

or

and n is an integer from 0-5 .

Di(tallowyloxyethyl)dimethylammonium chloride is particularly preferred.

A second preferred type of quaternary ammonium material can be represented by the formula:

wherein R¹, X⊃min;, n and R² are as defined above.

Preferred materials of this class, such as 1,2-bis[hardened tallowoyloxy]-3-trimethylammoniumpropane chloride and their preparation processes are described, for example, in US 4,137,180 (Lever Brothers). Preferably, these materials comprise small amounts of the corresponding monoester as described in US 4,137,180, for example 1-hardened tallowoyloxy-2-hydroxy-3-trimethylammoniumpropane chloride.

It is preferred if the quaternary ammonium compound is biodegradable. In the context of this invention, biodegradable means that the degradation leads to substances that are known to be harmless to the environment.

The ratio of quaternary ammonium material to non-ionic stabilizing agent is in the range of 5:0.5 to 5:0.1.

The composition may also contain long chain fatty acid material, for example C8-C24 alkyl or alkenyl monocarboxylic acids or polymers thereof. Preferably saturated fatty acids are used, in particular hardened tallow C16-C18 fatty acids. Preferably the fatty acid is not saponified, more preferably the fatty acid is free from, for example, oleic acid, lauric acid or tallow fatty acid.

The proportion of fatty acid material is preferably more than 0.1%, more preferably more than 0.2% by weight. Particularly preferred are dilute compositions in which the fatty acid material is present at 0.25% to 20% by weight. The weight ratio of the quaternary ammonium compound to the fatty acid material is preferably 1:10 to 10:1.

It is desirable that the viscosities of these textile compositions be in the range of 15 mPa·s to 120 mPa·s at a shear rate of 110 s⁻¹.

The compositions according to the invention preferably have a pH of more than 2, more preferably between 2 and 5.

The composition may also contain one or more optional ingredients selected from the group consisting of non-aqueous solvents, pH buffering agents, perfumes, perfume carriers, fluorescers, colorants, hydrotropes, antifoaming agents, antiredeposition agents, enzymes, optical brighteners, opacity agents, anti-shrinkage agents, pleating agents, antistatic agents and ironing aids.

The composition may also contain non-ionic fabric softening agents such as lanolin and derivatives thereof.

The invention will now be illustrated by the following non-limiting examples.

EXAMPLES

In the examples, all percentages are expressed as percent by weight.

Comparative examples are represented by a letter while examples of the invention are represented by a number.

In the examples, HEQ is 1,2-bis[hydrogenated tallowyloxy]-3-trimethylammonium propane chloride from Hoechst.

Production of textile conditioning composition

Liquid fabric softeners are prepared as follows:

The cationic fabric softening agent and/or fatty acid and/or non-ionic stabilizing agent, if appropriate, are premixed and heated together to form a clear melt. The molten mixture so formed was added to water at 70ºC to 80ºC to form a dispersion over a period of at least one minute with constant stirring.

Viscosity measurements

Viscosity was measured using a Haake RV20 rotoviscometer. Viscosity was reported at a shear rate of 10 s-1. Casson data are obtained using the Casson relation:

τ0.5 = τ00.5 + ην0.5·D0.5

wherein:

τ = shear stress (Pa)

?0 = yield stress (Pa)

η∞ = infinite shear rate viscosity (mPa·s)

D = shear rate (s⊃min;¹)

The Casson data are generated using the Haake RV20 rotoviscometer with a range of shear rates from 0- 1000 s⊃min;1.

Examples 1-2, comparative examples A-D

Compositions were prepared in which to an aqueous dispersion of 5% 6:1 HEQ:fatty acid, 0.5% of the following non-ionic surfactants was added:

Table 1

Example Non-ionic surfactant

A No non-ionic surfactant

B Genapol T-150

C-Tween 80

D Twean 85

1 Crodesta F50

2 Crodesta F110

Genapol, Tween and Crodesta are trademarks.

The effect of non-ionic surfactant type on the viscosity of a dilute quaternary ammonium compound is shown in Table 2. Table 2

It will be seen that the absence of non-ionic surfactant gives the composition a vesicular structure and thus an acceptable viscosity. However, the presence of stabilizing non-ionic surfactant agents not identified in this invention, such as Genapol T-150, Tween 80 and Tween 85, does not allow vesicle formation and thus the viscosity of the composition is unacceptably low. The examples according to the invention allow vesicle formation and have an acceptably high viscosity.

Comparison examples E-G

Compositions were prepared in which 0.5% of the following nonionic surfactants was added to a composition containing an aqueous dispersion of 5% 6:1 dihydrogenated tallow dimethyl ammonium chloride: fatty acid.

Example E non-ionic surfactant

Example F Genapol T-150

Example 6 Crodesta F50

The results are shown in Table 3. Table 3

Table 3 shows that non-ionic stabilizing agents do not destroy the viscosity in formulations containing dihydrogenated tallow dimethyl ammonium chloride.

Examples 3-10, comparison examples A-B

To a base formulation of 5% HEQ: hydrogenated tallow fatty acid 6:1 in water, the following non-ionic stabilizing agents were added:

The plasticizing performance of sugar esters is shown by Table 4. Table 4

95% significance is obtained when the difference (Δ) between the products is 0.9041. 90% significance is obtained when Δ = 0.7565. It is thus demonstrated that the sucrose esters show a significant plasticizing advantage.

Table 5 demonstrates an optimal proportion of monoester present to maximize the plasticizing effect. Table 5

Claims (6)

1. An aqueous fabric softening composition comprising: a) an aqueous dispersion of a water-insoluble quaternary ammonium material comprising at least one ester bond and two C12-28 alkyl or alkenyl groups; b) 0.1% to 2.5% by weight of the total composition of a non-ionic stabilising agent which is a sucrose ester, wherein the sucrose ester is a mixture of a monoester, diester and a triester, and 56 to 75 weight percent, based on the total weight of sucrose ester, is a sucrose monoester. 2. A fabric softening composition according to claim 1, wherein the ratio of quaternary ammonium material to non-ionic stabilizing agent is in the range of 5:0.5 to 5:0.1. 3. A fabric softening composition according to any preceding claim, wherein the viscosity of the composition is in the range of 15 mPa·s to 120 mPa·s at a shear rate of 110 s⁻¹. 4. A fabric softening composition according to any preceding claim, wherein the composition further comprises greater than 0.1% by weight of a fatty acid material. 5. Textile softening composition according to claim 4, wherein the fatty acid material is present at 0.25% to 20% by weight. 6. A process for preparing a liquid fabric softening composition comprising the steps of selecting the following ingredients: a) a water-insoluble quaternary ammonium material comprising at least one ester bond and two C₁₂₋₂₈ alkyl groups; b) a non-ionic stabilizing agent which is a mixture of sucrose monoester, sucrose diester and sucrose triester, wherein 56 to 75 percent by weight of the total weight of sucrose ester is sucrose monoester; c) other optional components; then mixing the ingredients with heating to form a melt, followed by dispersing the melt in water to form an aqueous dispersion of the water-insoluble quaternary ammonium material containing from 0.1% to 2.5% by weight of the total composition of the non-ionic stabilizing agent.