EP0920486A2

EP0920486A2 - Aqueous laundry softening agent with high zeta potential

Info

Publication number: EP0920486A2
Application number: EP97927127A
Authority: EP
Inventors: Ansgar Behler; Anneliese Wilsch-Irrgang; Theodor Völkel; Bernhard Guckenbiehl
Original assignee: Henkel AG and Co KGaA
Current assignee: Cognis IP Management GmbH
Priority date: 1996-06-14
Filing date: 1997-06-04
Publication date: 1999-06-09
Anticipated expiration: 2017-06-04
Also published as: WO1997047716A3; DE19623764A1; DE59706021D1; ES2171950T5; EP0920486B2; ATE212050T1; ES2171950T3; WO1997047716A2; EP0920486B1

Abstract

Aqueous softening dispersions which, in relation to the weight of the dispersion, contain 0.5 to 20 wt % of at least one non-ionic fat, 0.2 to 10 wt % of a water-soluble or insoluble cationic emulsifier and possibly upon to 10 wt % of a non-ionic emulsifier, in which the weight ratios between fat and emulsifiers is between 10:1 and 0.5:1, exhibit a good soft-care effect if the zeta potential of the dispersion is at least +30 mV at 25 DEG C and a pH of 7.

Description

Aqueous fabric softener with high zeta potential

The present invention relates to aqueous dispersions which contain fatty substances and emulsifiers as fabric softeners, which are distinguished by a high positive zeta potential of the dispersion.

Textile treatment agents which have a soft-care effect on laundry are well known. They are usually used in the last rinse of a machine wash and give the laundry a pleasant, soft feel, since they have a pronounced sorption capacity on a wide variety of fiber surfaces. The coating of the fibers with the long-chain molecules leads to a sliding effect between the fibers and thus prevents the water or dry rigidity that is responsible for the hard grip of the fabric. A possible adsorption mechanism for drawing up softening materials consists in the electrostatic attraction between the e.g. due to washing alkali negatively charged fiber surface and positively charged plasticizer particles. Statements about the size and the sign of the surface charge can be obtained by measuring the so-called zeta potential, which is the galvanic voltage across the diffuse electrochemical double layer at the phase boundary between the surface of a solid, for example a dispersed plasticizer, and a liquid. for example, the wash liquor.

Water-insoluble quaternary ammonium compounds which contain two long-chain alkyl or alkenyl radicals are usually used as textile-softening active substances. Frequently used compounds are ditallow dimethyl ammonium chloride or disartyl dimethyl ammonium chloride. However, since such compounds are considered to be ecologically questionable, increasingly used are difatty acid trialkanolamine ester salts which are obtained by reacting a trialkanolamine with technical fatty acids and subsequent quaternization, such as, for example, methyl-N- (2-hydroxyethyl) -N, N-di ( tallow acyl oxyethyl) ammonium methosulfate.

Usually, fabric softeners are offered in the form of aqueous dispersions. The problem arises here that the viscosity of the dispersion increases with an increasing proportion of active substance, which makes handling by the consumer more difficult, and Furthermore, the stability of such products is insufficient. In order to overcome such problems, for example, EP 043 622 B1 proposed an aqueous stable dispersion which contains 8 to 22% by weight of a water-insoluble cationic textile softener, and a viscosity-regulating system containing 0.5 to 6 % By weight C ₁₀ . ₂₄ - hydrocarbons, Cιo- ₂₄ fatty acids or Cιo- ₂₄ fatty acid esters from fatty acids with short-chain alcohols or Cιo- ₂ 4-fatty alcohols and 0.05 to 1 wt .-% of a water-soluble cationic polymer. However, the addition of polymers for viscosity control often leads to reduced performance of the fabric softener. Agents without polymeric viscosity regulators are described in DE 36 02 089 C2. In addition to conventional cationic textile softeners, the compositions contain a fatty alcohol with 10 to 24 carbon atoms, the weight ratio between cationic softeners to fatty alcohols being between 3.5: 1 and 6: 1. Ethoxylated amines are used as emulsifiers. Solid agents are known from German patent application 42 32 448 A1 which contain quaternary difatty acid trialkanolamine salts and a hydroxy compound selected from the group of fatty alcohols, fatty alcohol polyglycol ethers, polyol fatty acid partial esters and carbohydrates and which are suitable for the production of liquid, aqueous plasticizer compositions (with 1 up to 50% by weight of active substance). The weight ratio between quaternary esteramine salt and hydroxy compound should be between 9: 1 and 1: 1. However, a disadvantage of these agents is that relatively large amounts of ecologically unsatisfactory nitrogen-containing compounds are still used. In contrast, EP 497 769 A2 proposes acidic, aqueous fabric softeners which contain pentaerythritol esters as a softening component in amounts between 1 and 25% by weight and 0.1 to 10% by weight of a nonionic emulsifier and are therefore ecologically harmless are. However, the agents disclosed in this document can also contain up to 0.5% by weight of quaternized ammonium compounds. Such compositions, however, only have zeta potentials of at most +27 mV at pH = 7.

Despite these different approaches to producing stable, easy-to-handle textile softener dispersions, there is still a need to improve the existing formulations in terms of performance and ecological behavior. The object of the invention was therefore to produce stable, aqueous textile softener dispersions based on largely biodegradable ingredients with advantageous ecotoxicological properties. It has now been found that combinations of biodegradable, water-insoluble fatty substances with emulsifiers in specific proportions leads to efficient means if the zeta potential of the aqueous dispersions exceeds a certain value.

The invention therefore relates to fabric softening agents in the form of an aqueous dispersion of an anti-fouling component, the softening agent, based on the weight of the softening agent, consisting of 0.5 to 20% by weight of at least one nonionic fatty substance and 0.2 to 10% by weight .-% of a water-soluble and / or water-insoluble katio¬ African emulsifier and 0 to 10 wt .-% of a nonionic emulsifier, the weight ratio between fat and emulsifiers between 10: 1 and 0.5: 1 and the proviso that Zeta potential of the aqueous dispersion at a pH of 7 and a temperature of 25 ° C is at least + 30 mV.

In order to obtain agents with the desired zeta potentials, it is advantageous first of all to completely disperse the fatty substance with a suitable amount of nonionic emulsifier in water and then to set the zeta potential by adding the cationic emulsifier.

Measuring the zeta potential is a common method for characterizing solid / liquid dispersions (RJ Hunter, Zeta Potential in Colloid Science, pages 150 to 162, Academic Press, New York 1981). Dispersed particles can become electrically charged, for example through the adsorption of ions on their surface. As a result, an electrical double layer forms on the surface of these electrically charged particles, which is firmly bonded to the particles and causes an apparent increase in volume. This solid layer is enveloped by a movable and diffuse ion layer. The potential Ψo on the particle surface now drops within the solid ion layer with the thickness δ line¬ ar to the value ψ _δ in order to decrease exponentially to the value 0 in the diffuse layer. The potential difference between the inner solid ion layer ψ _δ and the point within the diffuse ion layer at which the potential has decreased to 1 / e ^• ψ _δ is called the zeta potential.

The zeta potential can be determined directly from the direction and speed of migration of the dispersed particles in the electric field (M. Hoffmann, H. Krömer, R. Kuhn, Polymeranalytik II, Georg Thieme Verlag, Stuttgart 1977, pages 260 to 264) , using the following relationship: f -π- v- η ζ =

E-ε ζ = zeta potential (in mV) ε = dielectric constant of the dispersing agent v = electrophoretic migration rate (in cm / s) η = viscosity of the dispersing agent (poise, 1 poise = 0.1 Pa • s)

E = field strength (in mV) f = numerical factor (friction factor), which depends on the shape of the particles, their conductivity and the size of the particles compared to the thickness of the diffuse double layer

Depending on the size of the particles to be examined, the migration speed is measured either by means of light microscopic observation or, in particular in the case of smaller particles, by means of laser correlation spectroscopy (W. Demtröder, laser spectroscopy: basics and techniques, 2nd edition, Springer-Verlag, Berlin 1991, chapters 12.7 to 12.7.2).

The high positive zeta potential of the dispersions means that the dispersed particles can completely absorb onto the negatively charged fibers and that the fibers are completely coated with hydrophobic, long-chain alkyl residues, which has a good softening effect. Agents are particularly suitable that have the highest possible zeta potential over a wide pH range, as is present in the wash liquor. Particularly preferred are dispersions according to the invention which not only have a zeta potential of at least + 30 mV at a pH of 7, but also at a pH of 8, which is often achieved in the wash liquor during the wash cycle show at least a zeta potential of + 25 mV (temperature 25 ° C each). Dispersions whose zeta potential shows at least + 40 mV at a temperature of 25 ° C. and a pH of 7 are particularly preferred.

The dispersions according to the invention contain at least one fatty substance in amounts between 0.5 and 20% by weight, preferably between 2 and 12% by weight and in particular between 4 and 6% by weight, based on the total amount of the agent, and the cationic emulsifier in amounts between 0.2 and 10% by weight, preferably between 0.3 and 8% by weight, in particular between 0.4 and 6% by weight, and optionally a nonionic emulsifier in amounts up to 10% by weight. It is essential that the weight ratio between fat and emulsifier is between 10: 1 and 0.5: 1 and the amounts of the ingredients are adjusted so that the zeta potential of the dispersion at a pH of 7 and 25 ° C is at least + 30 mV. Only then is it possible for softening substances to be absorbed onto the textile fibers in sufficient quantities, by one to achieve a good softening effect. Particularly preferred dispersions have a weight ratio between fat and emulsifiers of between 1: 1 and 8: 1, and in particular between 2: 1 and 6: 1.

In the context of these applications, fatty substances are understood to mean solid fats, fatty alcohols, waxes and hydrocarbons at normal temperature (20 ° C.). These include, for example, hardened fats and oils of animal and vegetable origin, as well as non-cyclic, branched and unbranched hydrocarbons with 12 to 30 carbon atoms. Examples of such compounds are tetradecane, hexadecane, octadecane and octa-decene. The fatty substances are preferably selected from the group of the fatty acid esters of fatty acids with 12 to 22 carbon atoms with mono- or polyhydric alcohols with 1 to 22 carbon atoms, as well as fatty acids or fatty alcohols with 12 to 22 carbon atoms and mixtures of these substances. In particular, mono- or diesters of fatty acids with pentaerythritol, Monoester and diesters of Cι ₂ - ₁ 8 acids with Gly or cerin Monoester of Cι ₂ .ιβ acids with Cι preferably ₂ -i ₈ fatty alcohols.

Examples of such compounds are lauric, myristic, palmitic or stearic acid and methyl and ethyl esters of these acids. For example, decanol, dodecanol, tetradecanol, pentadecanol, hexadecanol or octadecanol and mixtures of these alcohols are used as fatty alcohol. Examples of preferred fatty substances are technical pentaerythritol distearic acid esters or glycerol monostearic acid esters as well as technical fatty alcohols.

In the context of the present application, cationic emulsifiers are understood to mean compounds which are selected from the group of the quaternary ammonium compounds of the formulas (I) and (II),

R - X ^"

where R is an acyclic alkyl radical having 12 to 24 carbon atoms, R ^{1 is} a saturated C ₁ -C 4 alkyl or hydroxyalkyl radical, R ^{2 is} either R or R ¹ and COR ^{3 is} an aliphatic acyl radical having 12 to 22 carbon atoms is 0, 1, 2 or 3 double bonds and R ⁴ is H or OH, where n is 1, 2 or 3 and X is either a halide, methosulfate, metophosphate or phosphate ion, as well as mixtures of these compounds. Compounds which contain alkyl radicals having 16 to 18 carbon atoms are particularly preferred.

Examples of cationic surfactants of the formula (I) are didecyldimethylammonium chloride, ditallow dimethylammonium chloride or dihexadecylammonium chloride. Examples of compounds of the formula (II) are methyl-N- (2-hydroxyethyl) -N, N-di (tallow acyl-oxyethyl) ammonium methosulfate, bis- (palmitoyl) ethyl-hydroxyethyl-methyl-ammonium methosulfate or methyl-N, N-bis (acyloxyethyl) -N- (2-hydroxyethyl) ammonium methosulfate. In addition to the compounds of the formulas (I) and (II), it is also possible to use short-chain, water-soluble, quaternary ammonium compounds, such as, for example, trihydroxyethylmethylammonium methosulfate or cetyltrimethylammonium chloride. Protonated alkylamine compounds which have a softening effect and the non-quaternized, protonated precursors of the cationic emulsifiers are also suitable.

If quaternized compounds of the formula (II) are used which have unsaturated alkyl chains, preference is given to the acly groups whose corresponding fatty acids have an iodine number between 5 and 25, preferably between 10 and 25 and in particular between 15 and 20 and which have a cis / trans isomer ratio (in% by weight) of 30:70, preferably greater than 50:50 and in particular greater than 70:30.

In addition to the quaternary compounds described above, other known compounds can also be used, such as quaternary imidazolinium compounds of the formula (III)

where R ^{5 is} a saturated alkyl radical having 12 to 18 carbon atoms, R ^{6 is} an alkyl radical having 1 to 4 carbon atoms or H and Z is an NH group or oxygen and A is an anion.

Further suitable quaternary compounds are described by formula (IV) + (R ⁷ ) ₃ N— (CH ₂ ) _n - CH— OOCR ⁸

CH _? - OOCR ⁸

(IV) where R ⁷ each independently represents a C _1-4 alkyl, alkenyl or hydroxyalkyl group, R ⁸ each independently represents a C _8-28 alkyl group and n is a number between 0 and 5.

In the context of this application, nonionic emulsifiers are understood to mean compounds which are selected from the group of the alkoxylated fatty acids with 12 to 22 carbon atoms, the alkoxylated fatty acid esters from fatty acids with 12 to 22 carbon atoms with alcohols with 1 to 10 carbon atoms and the alkoxylated fatty alcohols with 12 up to 22 carbon atoms, the alkoxylated compounds having HLB values between 3 and 20, and fatty acid amides and monoalkanolamides from C ₂ -C ₂₂ fatty acids with amines or alkanotamines with 1 to 9 carbon atoms, and alkyl glycosides or glucamides, are selected. Preferably, alkoxylated compounds having an HLB value of between 3 and 20, preferably between 8 and 14. Example of the present invention, nonionic emulsifiers are C _{_12-1} 8- fatty alcohols with 7 EO, cetyl / stearyl alcohol with 20 EO or fatty acid. The alkyl glycosides used are compounds of the general formula RO (G) _x in which R denotes a primary straight-chain or methyl-branched, in particular methyl-branched aliphatic radical having 8 to 22, preferably 12 to 18, C atoms and G is the symbol which stands for a glycose unit with 5 or 6 carbon atoms, preferably for glucose. The degree of oligomerization x, which indicates the distribution of monoglycosides and oligoglycosides, is any number between 1 and 10; x is preferably 1.2 to 1.4.

Fatty acid N-alkylglucamides such as are represented by the formula (IV) are preferably used as glucamides,

10

OH OH OH

R CO-N-CH -CH-CH-CH-CH-CH OH (IV)

2 2

OH 10 9 wherein R is hydrogen or an alkyl group and R CO is the acyl radical of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, arachic acid , Gadoleic acid, behenic acid or erucic acid or their technical mixtures. Particularly preferred are fatty acid N-alkyl glucamides of formula (IV) / ι by reductive amination of glucose with methylamine and subsequent acylation with lauric acid or coconut oil fatty acid C ₁₂ ₄ a corresponding derivative are obtained respectively.

In addition to the ingredients mentioned above, the agents according to the invention can also contain other substances customary in textile softeners. These include, for example, organic solvents such as ethanol or isopropyl alcohol, fungicides, enzymes, for example cellulase, dyes, optical brighteners, lecithin, UV absorbers, preservatives, soil repellents, pearlescent agents or fragrances. The agents may further contain electrolytes, preferably sodium, magnesium or calcium chloride, and pH adjusting agents such as e.g. organic and inorganic acids.

The dispersions according to the invention are prepared in a manner known per se by mixing the ingredients with the necessary amount of water, then heating to a temperature of 60 ° C. and mixing for 5 to 30 minutes in a high-speed mixer. The aqueous white rinse dispersions thus obtained have a pH between 2 and 7, preferably between 3 and 6.

Examples

The aqueous dispersions mentioned in Examples 1 to 8 were prepared by introducing the corresponding fatty substances with the emulsifiers and water and heating them to 80 ° C. with thorough mixing. After the raw materials had been homogeneously dispersed, the cationic emulsifier was added with thorough mixing. The dispersion was cooled to 30 ° C. with moderate stirring and then the remaining constituents, such as, for example, perfume oils, were metered in.

The zeta potentials of the aqueous dispersions and the assessment of the gripping effect can be found in Table 1.

The determination of the gripping effect was carried out on prewashed terry towels, which were equipped with the agents to be examined and then dried in the air. For this purpose, the test fabrics were treated in a glass drum with the agents to be examined (concentration 15 g / kg dry wash, water hardness 16 ° d, liquor ratio 1: 5) for 5 minutes, the drum being set in reversing movements. The cloths were assessed by a test panel (5 people) in terms of grip. The laundry handle was given as an average of three determinations in grades (0 = hard, 6 = soft), grades from 3.8 being rated as good.

The zeta potential was measured using a Malvern-Zetazisers ^® 3 at a temperature of 25 ° C. To determine the zeta potential, the respective dispersion was diluted 1: 400 with 0.001 molar potassium chloride solution and then the pH was adjusted to the desired value using hydrochloric acid or sodium hydroxide. The values given represent mean values from 5 measurements.

The dispersions according to the invention, with a small proportion of quaternary N-containing compounds, had good grip properties which are comparable with the performance of conventional plasticizers which contain only cationic N-containing salts as the finishing component.

For comparison, the two examples 7 and 8 not according to the invention and a commercial plasticizer 9 based on a known quaternary esteramine salt were investigated. Although 7 has a combination of fatty substance and cationic and nonionic emulsifier, the zeta potential at pH = 7 is below + 30 mV. 8 represents a combination of a cationic and two nonionic emulsifiers without the addition of a fatty substance according to the invention. Example 10 shows that the combination tion of the ingredients according to the invention does not necessarily lead to dispersions with high zeta potential.

For all of the example compositions, the absence of amounts means up to 100% by weight of water and minor other constituents (electrolytes, perfume oil, auxiliaries, etc.).

example 1

1.26 wt .-% of C16 fatty alcohol ₁ 8

0.70% by weight methyl laurate +12 EO

0.54 wt% bis (palmytoyl) ethyl hydroxyethyl methyl ammonium methosulfate

Example 2

5.00% by weight di-Ciβ-iβ-alkyl-pentaerythritol ester

0.36% by weight of trimethyl hexadecyl ammonium chloride

0.30 wt .-% C ₁₂ ι ₆ fatty alcohol-1,4-glycoside

Example 3

7.70 wt .-% Di-C _16-i ₈ alkyl pentaerythritol ester

0.82% by weight tallow amine + 2 EO adduct (commercial product Genamin ^® T 020, Hoechst)

1.25% by weight tris (oligooxyethyl) alkylammonium phosphate

Example 4

5.00 wt .-% Di-Cι ₆ .i8-alkyl-pentaerythritol ester

1.08% by weight of methyl-N- (2-hydroxyethyl) -N, N-di (tallow acyloxyethyl) ammonium methosulfate

0.56% by weight of methyl laurate +12 EO

Example 5

4.00% by weight of C ₁₆ fatty alcohol

1.35% by weight of methyl-N- (2-hydroxyethyl) -N, N-di (tallow acyloxyethyl) ammonium methosulfate

0.75% by weight of methyl laurate +12 EO

Example 6

4.00% by weight glycerol mono-di-palmitate

0.90% by weight of methyl laurate +12 EO

Example 7

5.00 wt .-% di-C _{_16-1} 8-alkyl-pentaerythritol ester

0.17% by weight of methyl-N, N-bis (acyloxyethyl) -N- (2-hydroxyethyl) ammonium methosulfate

1.26% by weight of methyl laurate +12 EO Example 8

2.50% by weight of C ₁₂ .i6-fatty alcohol-1,4-glycoside

0.19% by weight of methyl-N, N-bis (acyloxyethyl) -N- (2-hydroxyethyl) ammonium methosulfate

0.84% by weight of methyl laurate +12 EO

Example 9

4.50% by weight of methyl N- (2-hydroxyethyl) -N, N-di (tallow acyloxyethyl) ammonium methosulfate

Example 10

5.00% by weight di-Ciβ-iβ-alkyl-pentaerythritol ester

1.28 wt .-% Cι ₂ -i ₈ fatty alcohol +7 EO

0.82 wt .-% tallow amine 2 EO-adduct (Genamin ^® T 020, Fa. Hoechst)

0.50% by weight of methyl N- (2-hydroxyethyl) -N, N-di (tallow acyloxyethyl) ammonium methosulfate

Table 1

Zeta potential [mV]

Composition pH = 7 pH = 8 note

1 52 52 4.7

2 41 38 3.9

3 42 30 4.7

4 45 45 4.8

5 52 41 4.7

6 52 44 4.3

7 24 27 2.6

8 - 35 - 32 1, 5

9 65 65 5.0

10 27 23 3.5

Claims

claims

1. Fabric softener in the form of an aqueous dispersion of a softening component, characterized in that the softening component, based on the weight of the fabric softener, from 0.5 to 20 wt .-% of at least one nonionic fat and 0.2 to 10 wt .-% of one water-soluble and / or water-insoluble cationic emulsifier and 0 to 10% by weight of a nonionic emulsifier, the weight ratio between fat and emulsifiers being between 10: 1 and 0.5: 1 and the proviso that the zeta potential of the aqueous dispersion at a pH of 7 and a temperature of 25 ° C is at least + 30 mV.

2. Laundry softener according to claim 1, characterized in that the water-insoluble nonionic fat is selected from the group of fatty acid esters of fatty acids with 12 to 22 carbon atoms with mono- or polyhydric alcohols with 1 to 22 carbon atoms, and fatty acids and fatty alcohols with 12 to 22 carbon atoms and mixtures of these substances.

3. fabric softener according to one of claims 1 or 2, characterized in that as the fatty substance mono- or diesters of fatty acids with pentaerythritol, monoesters and diesters of C ₂ - ₁₈ fatty acids with glycerol or monoesters of C ₂ -iδ fatty acids with C _{2 -} ₁ 8 fatty alcohols is included.

4. Fabric softener according to one of claims 1 to 3, characterized in that the water-insoluble cationic emulsifier is selected from the group of the quaternary ammonium compounds of the formulas (I) or (II)

R - X ^"

(D (II) where R is an acyclic alkyl radical having 12 to 24 carbon atoms, R ^{1 is} a saturated C ₁ -C ₄ alkyl or hydroxyalkyl radical, R ^{2 is} either R or R ¹ and COR ^{3 is} an aliphatic acyl radical having 12 to 22 carbon atoms is 0, 1, 2 or 3 double bonds, and R ⁴ is H or OH, where n is 1, 2 or 3 and X is either a halide, methosulfate or metophosphate ion, and mixtures of these compounds.

5. fabric softener according to one of claims 1 to 4, characterized in that the nonionic emulsifier is selected from the group of alkoxylated fatty acids with 12 to 22 carbon atoms, alkoxylated fatty acid esters from fatty acids with 12 to 22 carbon atoms with alcohols with 1 to 10 carbon atoms, alkoxylated Fatty alcohols with 12 to 22 carbon atoms, the alkoxylated compounds having HLB values between 3 and 20, and fatty acid amides and monoalkanolamides from C ₂ -C ₂₂ fatty acids with amines or alkanotamines with 1 to 9 carbon atoms, and also alkyl glycosides or glucamides.

6. fabric softener according to one of claims 1 to 5, characterized in that the aqueous dispersion at pH = 7 and a temperature of 25 ° C has a zeta potential of at least + 40 mV.

7. fabric softener according to one of claims 1 to 6, characterized in that the aqueous dispersion at pH = 8 and a temperature of 25 ° C has a zeta potential of at least + 25 mV.

8. fabric softener according to one of claims 1 to 6, characterized in that the weight ratio between fat and emulsifier is between 1: 1 and 8: 1, preferably between 2: 1 and 6: 1.