EP1080172B1

EP1080172B1 - Stable quaternary ammonium compositions

Info

Publication number: EP1080172B1
Application number: EP99929121A
Authority: EP
Inventors: David William Unilever Res. Port SL. THORNTHWAITE; Christopher Unilever Res. Port Sunlight WHALEY
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1998-05-18
Filing date: 1999-05-12
Publication date: 2005-05-04
Anticipated expiration: 2019-05-12
Also published as: HUP0101902A2; CN1280389C; AR019556A1; ES2241289T3; TR200003385T2; BR9910550A; DE69925119D1; HUP0101902A3; AU4604599A; CA2329959A1; GB9810656D0; BR9910550B1; CA2329959C; EP1080172A1; CN1301292A; DE69925119T2; WO1999060082A1

Description

Technical field

The present invention relates to the stability of quaternary ammonium materials, in particular it relates to maintaining stable quaternary ammonium materials containing at least one ester group, in the raw material form or as a solution in a suitable solvent.

Background and prior art

Quaternary ammonium materials both solid or liquid are used extensively in fabric softener compositions. Typically such compositions contain a water insoluble quaternary ammonium fabric softening agent dispersed in water at a level of quaternary ammonium softening agent up to 8% by weight in which case the compositions are considered dilute or at levels from 8 to 50% in which case the compositions are considered concentrates.
The problem associated with quaternary ammonium materials containing at least one ester group is their instability on storage.
The problem is particularly noticeable in the storage of these materials at variable temperatures over time, especially at elevated temperatures eg in the region of 40-90°C, such as 50-85°C.
The instability of both such solid and liquid quaternary ammonium material may manifest itself by the discolouration of such material during storage at various temperatures.
The amount of discolouration is generally an indication of the level of decomposition occurring over time. This decomposition is of greatest concern when quaternary ammonium material is stored at temperatures above their melting points.
Instability may also manifest itself by alkyl halide appearance in the sample, indicating decomposition of the quaternary ammonium material. Instability may be referred to as caused by, or indicated by, de-quaternisation of the quaternary ammonium material.
In the past, stability of quaternary ammonium compounds has been improved by the storage of compounds at low temperatures, i.e. temperatures well below the melting points of the compounds being stored. Also, the addition of anti-oxidants has been used to counteract decomposition.
EP 299 176 (Kao) discloses soft-finishing agents comprising a di-long chained quaternary ammonium salt containing a single ester group and a decyldimethyl amine.
EP 499 282 (Hoechst) discloses compositions comprising a quaternary ammonium compound and an aliphatic amine.
EP 332 270 (Unilever) discloses compositions comprising a quaternary ammonium fabric softening agent, an amine and an amphoteric material.
DE 2454465 (Hoechst AG) discloses powder-based material with disinfecting components.
US 5543067 (P & G) discloses softening compositions comprising a mixture of an ester-functional quaternary ammonium compound and a polyhydroxy compound.
DE 4307186 (Henkel) discloses dilute aqueous softening compositions.
DE 19629666 (Henkel) discloses softening compositions comprising diester quaternary ammonium compounds and glycerine.
US 5282983 (Kao) discloses aqueous fabric softener compositions comprising a softener material obtained by neutralising a di-long chain type tertiary amine compound.
EP 0547723 (Colgate-Palmolive) discloses free-flowing spraydried particulate fabric softening compositions comprising 45 to 85% by weight of urea.
US 4851138 (Akzo) discloses a detergent compatible granular fabric softening composition comprising a water soluble quaternary ammonium compound and an amide,
Surprisingly, we have found that low and high temperature stability of the aforementioned solid or liquid quaternary ammonium compounds may be improved by the addition of at least one stabilising agent selected from specific group of compounds which improve the stability of the composition.

Definition of the invention

Thus according to one aspect of the invention there are provided improved stable compositions comprising a quaternary ammonium material of formula
where each R¹ group is methyl; and each R² group is tallowyl; X^- is chloride,
T is
and
n is 2
characterised in that they further comprise one or more stabilising agent(s) chosen from;
a) urea
b) urea derivatives
c) one or more organic compounds having at least one free lone pair of electrons chosen from;
i) primary amines RNH₂, where R is a C_3-17 alkyl, alkenyl, hydroxyalkyl or substituted derivative thereof,
ii) secondary amines, and/or
iii) tertiary amines NR¹R²R³ wherein R¹R²R³ are independently C₁ -C₂₂ alkyl, alkenyl or hydroxyalkyl groups or substituted derivatives thereof, and wherein when both R¹ and R² are -CH₂CH₂OH or both R¹ and R² are -CH₂CH₂OCOR⁴, R⁴CO is C_16-18, then R³ is not a methyl group
d) glycerol
Such compositions show improved stability at varying temperatures.
In a second aspect of the present invention there is provided a process of stabilising the aforementioned quaternary ammonium material by the addition of one or more stabilising agents as defined above, at levels as defined above.
According to a further aspect of the invention is provided a solid rinse conditioner comprising a composition as defined above.
According to a further aspect of the invention is provided a liquid rinse conditioner made by dilution of a composition as defined above with water.
According to a further aspect of the invention is provided a method of reducing the alkyl halide levels in the aforementioned quaternary ammonium material over time by the addition of a stabilising as defined herein, at levels as defined herein.

Detailed description of the invention

The quaternary ammonium materials of the invention preferably do not contain substantial amounts of non- ester containing material. Preferably the ester containing quaternary ammonium material is used in the absence of non-ester group quaternary ammonium containing material. However where necessary small amounts eg less than 20% by weight based on the amount of total quaternary ammonium material, preferably less than 10% may be present.
The problems identified above have especially been found to be associated with quaternary ammonium materials with two or three electron withdrawing groups attached to the quaternary nitrogen atom through a hydrocarbyl (alkyl) chain of one or two carbon atoms, and, one or two short alkyl chains, (especially methyl) also directly attached to the nitrogen atom. This arrangement is shown in formula (A) below. Compounds of type A having two methyl groups and two electron withdrawing groups attached to the quaternary nitrogen atom through an alkyl chain of two carbon atoms are of particular application in the present invention. Such compounds having a chloride counterion have been found to especially benefit from the present invention.
It is believed that the problems identified above are most common in quaternary ammonium materials having an ester linking group and one or two methyl groups attached directly to the quaternary nitrogen atom, a chloride counterion, and two electron withdrawing groups separately linked to the quaternary nitrogen atom. The compounds of general formula A may suffer most from the problems identified above and are especially preferred according to the invention.
The ester-linked quaternary ammonium material for use in the invention is represented by the formula:
wherein each R¹ group is methyl; and wherein each R² group is tallowyl; X^- is chloride
T is
and
n is 2.
Di(tallowyloxyethyl) dimethyl ammonium chloride, available from Hoechst, is especially preferred, also Di(hardened tallowyloxyethyl)dimethyl ammonium chloride, ex Hoechst).
It is also preferred that the quaternary ammonium compound used in the present invention is substantially anhydrous, meaning containing less than 10% water in the context of the present invention.
The quaternary ammonium material may contain optional additional components, as known in the art, in particular, low molecular weight solvents, for instance isopropanol and/or ethanol, and co-actives such as nonionic softeners, for example fatty acid or sorbitan esters.
Any of the above-mentioned stabilising agents may be used according to the invention.
The stabilising agent is added to the composition of the present invention at levels of 0.05 to 10% by weight of the weight of the quaternary ammonium material, more preferably 0.5 to 8.5% and even more preferably 0.75 to 7.5%, eg 1 to 5%.
In the tertiary amine stabilising agents the R¹R²R³ substituents include OCOR4 substituents wherein R⁴ is a C₁₂-C₂₂ alkyl or alkenyl chain.
A combination of glycerol and a quaternary ammonium compound of general formula (A), especially DEQ, has been found to be advantageous.
The most preferred stabilising agents are urea and tertiary amines where R¹ and R² are C₁ - C₂ alkyl groups and R³ is a C₂ - C₄ hydroxyalkyl group eg N,N-dimethyl ethanolamine (DMEA).
The stabilising agent may be introduced to the quaternary ammonium material at any stage during its manufacture or after manufacture, eg on storage. The stabilising agent may be added in any form, as a powder direct to the molten quaternary ammonium material or as a solution in a suitable solvent, for instance isopropanol.
The addition of the stabilising agent can take place during the synthesis of the quaternary ammonium material preferably following the quaternisation step. The addition may alternatively, or additionally, be made during storage of the quaternary ammonium material.
The stabilising agent is most effectively introduced at any stage following the quaternisation step of the synthesis of the quaternary ammonium material.
The composition is in a liquid, molten or semi molten form containing less than 10% by weight of water. These compositions may be incorporated into a solid rinse conditioner which is preferably in a powdered or granular form. The compositions may also be diluted with water to produce a liquid rinse conditioner.

Examples

The invention will now be illustrated by the following examples. Further examples within the scope of the present invention will be apparent to the skilled person in the art.

Example 1

Urea was added to the quaternary ammonium material as a powder and heated to 82°C. The combined material was stored for three days.

The reflectance was measured on a datacolor international Spectraflash SF600 plus reflectometer after 3 days storage at 82°C.

	R540 after 3 days at 82°C
DEQ (control)	19.8
DEQ + 3.6% urea	25.1
DEQ + 7.3% urea	27.4
DEQ is di(2-[hardened tallow]oxyl oxyethyl) dimethyl ammonium chloride ex Hoechst. It includes approximately 10% mono ester and minor amounts of unquaternised amine/amine salt as well as approximately 2% fatty acid and 14% isopropanol.

These results show that addition of urea to compositions comprising a quaternary ammonium compound counteracts decomposition at particularly high temperatures. This is indicated by the greatly increased R540 reflectance values found for samples of quaternary ammonium compound stored in admixture with urea.
The following examples show the reduction in decomposition of the quaternary ammonium material by the reduction in liberation of alkyl halide on incorporation of a stabilising agent in accordance with the present invention.
Alkyl halide is produced by the following decomposition reaction: R₂ Me₂ N⁺Cl^- → R₂NMe+ MeCl R¹ Me₃ N⁺Cl^- → R¹NMe₂+ MeCl where R is a C₈ to C₂₂ hydrocarbyl group, optionally interrupted by functional groups, e.g. ester [O-CO., CO.O], amide, ether, amine, carbonate), optionally branched, optionally unsaturated and R¹ is a C₈ to C₄₀ hydrocarbyl group similarly defined.

Example 2

Urea was mixed with DEQ prior to heating at 82°C.

The chloromethane levels were determined by capillary gas chromatography.

Formulation	MeCl (ppm) after 3 days at 82°C
DEQ (control)	283
DEQ plus 3.6% urea	52
DEQ plus 7.3% urea	24
DEQ is di(2-[hardened tallow]oxyl oxyethyl) dimethyl ammonium chloride ex Hoechst. It includes approximately 10% mono ester and minor amounts of unquaternised amine/amine salt as well as approximately 2% fatty acid and 14% isopropanol.

Example 3

DMEA was added to the DEQ following storage of the DEQ overnight at 82°C. Chloromethane was determined by gas chromatography after a further day at 82°C.

Formulation	MeCl (ppm) after storage at 82°C
DEQ (control)	80 (1 day)
DEQ plus 0.76% DMEA	32 (1 day)
DEQ plus 2.28% DMEA	5 (30 minutes)
DEQ plus 2.28% DMEA	2 (1 day)
DMEA is N,N-dimethylethanol amine (99% ex Aldrich)

All examples above demonstrate that the addition of DMEA reduces the level of methyl chloride generation over time in quaternary ammonium material stored at high temperatures. The level of decomposition is reduced thus resulting in more stable quaternary ammonium material. Furthermore the result after 30 minutes for the addition of DMEA shows the rapid and excellent effect thereof upon the level of methyl chloride.

Example 4

Glycerol was added at a level of 7.5% by weight to a sample of DEQ to produce example 4A. A control sample of DEQ which did not contain any glycerol (Comparative example 4B) and example 4A were sealed in separate Gas Chromatograph (GC) vials and were stored at 80.5°C. At the end of the storage period the level of 'total' methyl chloride in each sample was measured. The results are given below.

Example 'Total' MeCl (ppm) after 9 days storage at 80.5°C.

4A 173

4B (comparative) 378
The above results demonstrate the ability of the stabilising agent, here glycerol, to reduce the level of MeCl in a quaternary ammonium material on closed, high temperature, storage. The level of MeCl measured here is the 'total' level in a sealed system.

Claims

Stable compositions comprising a quaternary ammonium material of formula
where each R¹ group is methyl; and each R² group is tallowyl; X^- is chloride,
T is
and
n is 2
characterised in that they further comprise one or more stabilising agent(s) chosen from;

a) urea

c) urea derivatives

c) one or more organic compounds having at least one free lone pair of electrons chosen from;

i) primary amines RNH₂, where R is a C_3-17 alkyl, alkenyl, hydroxyalkyl or substituted derivative thereof,

ii) secondary amines, and/or

iii) tertiary amines NR¹R²R³ wherein R¹R²R³ are independently C₁ -C₂₂ alkyl, alkenyl or hydroxyalkyl groups or substituted derivatives thereof, and wherein when both R¹ and R² are -CH₂CH₂OH or both R¹ and R² are -CH₂CH₂OCOR⁴, R⁴CO is C_16-18, then R³ is not a methyl group

d) glycerol

with the proviso that the composition is in a liquid, molten or semi-solid form containing 10% or less water, wherein the stabilising agent is present at levels of 0.05 to 10% by weight of the weight of the quaternary ammonium material, preferably 0.5 to 8.5%, even more preferably 0.75 to 5%.
A composition according to claim 1 wherein the stabilising agent is urea or a tertiary amine wherein R¹ and R² are C₁-C₂ alkyl groups and R³ is a C₂ - C₄ hydroxyalkyl, preferably N-N-dimethyl ethanolamine.
A process of stabilising the quaternary ammonium material of claim 1 via the steps of adding at least one stabilising agent of claim 1 to the quaternary ammonium material, wherein the stabilising agent is present at levels of 0.05 to 10% by weight of the quaternary ammonium material, preferably 0.5 to 8.5%, even more preferably 0.75 to 5%.
Process according to claim 3 wherein addition of the stabilising agent occurs during the manufacture of the quaternary ammonium material, preferably following the quaternisation step in the synthesis of the quaternary ammonium material.
Process according to either claim 3 or claim 4 wherein addition of the stabilising agent occurs after manufacture of the quaternary ammonium material, preferably during storage thereof.
A solid rinse conditioner comprising a composition as defined in claim 1 or claim 2, preferably in granular or powdered form.
A liquid rinse conditioner made by dilution of a composition as defined in claim 1 or claim 2, with water.
Method of reducing the alkyl halide levels in the quaternary ammonium material of claim 1 group over time by the addition of a stabilising agent as defined in claim 1, wherein the stabilising agent is present at levels of 0.05 to 10% by weight of the quaternary ammonium material, preferably 0.5 to 8.5%, even more preferably 0.75 to 5%.