The present invention relates to concentrated fabric-softening compositions in liquid form, to be used in the rinse step of the laundry cycle.
Fabric-softening compositions to be added in the rinse step of a laundry cycle are well known in the art and have found wide-scale commercial application.
In addition to achieving excellent fabric-softening performance, it has been, in recent years, the objective of fabric softener manufacturers to provide compositions which have an increased biodegradability.
Accordingly, ester-containing fabric-softening actives have been disclosed, to be used in replacement of, or in combination with, conventional quaternary softening actives. Such ester-containing actives include the imidazoline ester derivatives disclosed in e.g. GB 1,561,808 and further disclosed in e.g. EP-A-345 842.
It has been found, however, that concentrated compositions containing said ester imidazoline compounds have a tendency to develop an odor off-note, on prolonged storage.
The present invention is based on the discovery that such a problem is surprisingly cured by the incorporation in said concentrated compositions of a small amount of chelating agent for heavy metal ions.
In U.S. Patent 3, 756,950 are disclosed fabric-softening compositions containing conventional quaternary ammonium softening actives and an acid salt of amino-carboxylic acid chelating agent, to decrease fabric yellowing.
The present invention encompasses concentrated fabric-softening compositions containing at least 10% by weight, preferably 15 to 25% by weight of an imidazoline ester softening active of the formula :
wherein X and X1 are, independently, C11-C21 hydrocarbyl groups, preferably C13-C17 alkyl, and m and n are, independently, from 2 to 4, preferably 2,
and a Bronstedt acid as levels such as to have a pH below 4, characterized in that, it contains a chelating agent for heavy metal ions, at levels of from 0.01% to 1%, preferably 0.05 to 0.2% of the composition.
The compositions of the present invention contain at least 10%, preferably from 15% to 25% of a substituted imidazoline ester softening compound having the formula
wherein X and X¹ are, independently, C₁₁-C₂₁ hydrocarbyl groups, preferably C₁₃-C₁₇ alkyl, most preferably straight chain C₁₇ alkyl, and m and n are, independently, from 2 to 4, preferably m and n are both 2. The total concentration of softener active cannot exceed about 40% by weight. It will be understood that substituents X and X¹ may optionally be substituted with various groups such as alkoxyl, hydroxyl, or can be branched, but such materials are not preferred herein. In addition X and/or X¹ may optionally be unsaturated (i.e., alkenyl groups). The preferred substituted imidazoline ester softening compounds will hereinafter be referred to as di-alkyl imidazoline ester compounds. Most preferred is ditallow imidazoline ester.
The pH, measured in distilled water at 3% dilution of the present compositions should be not greater than 4, preferably from 2.5-4.
To achieve such a pH, a Bronstedt acid having a pKa value of 6 or less, is present in the present composition.
Examples of suitable acids include the inorganic mineral acids, carboxylic acids, in particular the low molecular weight (C₁-C₅) carboxylic acids, aromatic carboxylic acids, like benzoic acid, and alkylsulfonic acids.
Suitable ionorganic acids include HCl, HBr, H₂SO₄, HNO₃ and H₃PO₄. Suitable organic acids include benzoic acid, formic, acetic, methylsulfonic and ethylsulfonic acid. Preferred acids are phosphoric, formic, and methylsulfonic acid.
The compositions herein comprise a liquid carrier, e.g., water, preferably a mixture of water and a C₁-C₄ monohydric alcohol (e.g., ethanol, propanol, isopropanol, butanol, and mixtures thereof), isopropanol being preferred. These compositions comprise from 60% to 98%, preferably from 70% to 95% of the liquid carrier. Preferably, the amount of the C₁-C₄ monohydric alcohol in the liquid carrier is from 5% to 50% by weight of the softening compounds, the balance of the liquid carrier being water.
The chelating agents are present at levels of from 0.01% to 1% of the compositions herein, preferably from 0.05 to 0.2%.
The chelating agents for heavy metal ions useful herein include any material known in the art for that purpose.
Suitable compounds include the following carboxylic acids and salts thereof : citric acid, tartaric acid, oxydisuccinic acid, ethylene diamine -N,N disuccinic acid, oxydiacetic acid, carboxymethyltartronic acid, carboxymethyloxysuccinic acid, tartrate monosuccinic acid/tartrate disuccinic acid blend at 80:20 weight ratio, as well as 2-dodecenyl succinic acid, and dodecyl succinic acid.
This category also includes polycarboxylic acids and salts thereof, such as polyacrylates and copolymers of maleic and acrylic acids.
Other suitable compounds are the following amino-carboxylic acids and salts thereof, as nitrilotriacetic acid, ethylene diamine tetracetic acid, cyclo ethylene diamine tetracetic acid, trans 1,2 diamino cyclohexane N,N,N',N' tetraacetic monohydrate (CHELCD), hydroxyethylenediamine tetracetic acid, diethylene triaminopentacetic acid, N-glyceryl imino diacetic acid, N(-2 hydroxypropyl) iminodiacetic acid;
Polyamino polyalkylene phosphonic acids and salts thereof such as ethylenediamine tetramethylenephosphonic acid and diethylene triamine pentamethylenephosphonic acid are also suitable as chelating agents hereof.
Fully-formulated fabric softening compositions may optionally contain, in addition to the substituted imidazoline ester softening compounds of the formula herein, the liquid carrier and the acid, one or more of the following ingredients.
The compositions of the present invention can further comprise a di(higher alkyl) quaternary ammonium softening agent. The compositions herein can contain from 0% to 25% (preferably from 0.1% to 10%) of the di(higher alkyl) quaternary ammonium softening agent.
The quaternary softening agents useful herein are selected from the group of
- (i) acyclic quaternary ammonium salts having the formula:
Rapidly biodegradable compounds of formula (i) where R₂, and possibly R₄, are interupted by ester groups, are disclosed in EPA 239 910. - (ii) diamido quaternary ammonium salts having the formula :
- (iii) diamido alkoxylated quaternary ammonium salts having the formula :
- (iv) quaternary imidazolinium compounds having the formula :
Examples of Component (i) are the well-known dialkyldimethylammoniums salts such as ditallowdimethylammonium chloride, ditallowdimethylammonium methylsulfate, di(hydrogenated tallow) dimethylammonium chloride, dibehenyldimethylammonium chloride.
Examples of Component (ii) and (iii) are methylbis(tallowamidoethyl) (2-hydroxyethyl) ammonium methylsulfate and methylbis(hydrogenated tallowamidoethyl) (2-hydroxyethyl) ammonium methylsulfate, wherein R₁ is an acyclic aliphatic C₁₅-C₁₇ hydrocarbon group, R₂ is an ethylene group, R₅ is a methyl group, R₈ is a hydroxyalkyl group and A is a methylsulfate anion; these materials are available from Sherex Chemical Company under the trade names VarisoftR 222 and VarisoftR 110, respectively.
Examples of component (iv) are 1-methyl-1-tallowamino-ethyl-2-tallowimidazolinium methylsulfate and 1-methyl-1-(hydrogenated tallowamidoethyl)methylsulfate.
The ratio of quaternary ammonium salt to cyclicamine should not exceed 10:1, and preferably does not exceed 2:1.
The aqueous dispersion of quaternary softening agent is prepared in a conventional way, typically by injecting the quaternary material in a molten form in a batch containing water, with continuous agitation.
Once this dispersion is prepared, the concentrated composition resulting from steps a) to d) will be added to it;
In case of a continuous process, said concentrated composition will, immediately after step d) be added to the aqueous dispersion of quaternary ammonium compound.
In an alternative and convenient way, the concentrated composition obtained after step d) will first be cooled to a temperature of from 15 to 25°C, (room temperature) and then some time will be allowed for e.g. storage, shipment of the concentrated composition, before it is added to the aqueous dispersion of quaternary softening agent.
In any case, the viscosity of the finished product will be in a range of 20 to 500 cp, preferably 50 to 150 cp.
The co-softening agents for use herein can be selected from fatty acid esters of polyhydric alcohols having up to 8 carbon atoms such as described in DE-A-26 31 114. Examples of the like esters include sorbitan esters and glycerol esters such as sorbitan monostearate, sorbitan monooleate, glycerol mono-di- and tri-fatty acid esters wherein the acid is selected from stearic, oleic, lauric, capric, caprylic, caproic, valeric, butyric, propionic and acetic acid; an individual glycerol can be esterified by identical fatty acid groups or by mixed esters e.g. glycerol monostearatedioleate. Polyethyleneglycol esters monostearate, wherein the polyethyleneglycol moiety has a molecular weight in the range from 200 to 400 are also included in that class. Fatty acid esters of monohydric alcohols having at least 4 carbon atoms such as isobutyl stearate and ethyl hexyl stearate can also be useful.
Additional co-softening agents which can be used are : glycerol, diglycerol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, dihexylene glycol, polyethylene glycol (MW 200-100.000), polypropylene glycol (MW 200-100.000), polyvinylalcohol, polyoxyethylenepolyoxypropylene copolymers, polypropylene glycol (MW 900), glucose methylether, butyldiglycolether, diethyleneglycolmonobutylether, propyleneglycolmonoethyl or ethyl ether, ethylene carbonate, propylene carbonate.
Useful also are alkylpolyglucosides of the general formula R₂O(CnH2nO)t (glucosyl)x wherein R² is alkyl, alkylphenyl, hydroxyalkyl, hydroxyalkylphenyl and mixtures thereof wherein the alkyl chain has from 8 to 18 carbon atoms, t is from 0 to 2 and x from 2 to 7, can also be used in the composition. These glucosides exhibit desirable solvent properties and in addition can confer fiber benefits such as softness.
Lanolins and derivatives and paraffins having from 16 to 20 carbon atoms constitute another example of non-ionic agents which can be used if desired. Low melting oils from animal, vegetable or mineral origin are representative of this class of materials. Carnation oilR, Jojoba oilR and Sunflower oil are specific examples which are found to work.
Another important class of co-softening agents is represented by materials of the general formula :
R₁COOR₂
wherein R₁ is a straight or branched chain alkyl or alkenyl group having from 8 to 23 carbon atoms and R₂ is hydrogen or an alkyl or hydroxyalkyl group having 1-4 carbon atoms.
Highly preferred materials of this class are the C₁₀ to C₂₀ saturated fatty acids, especially lauric acid, myristic acid, palmitic acid and stearic acid.
Also suitable are linear fatty C₈₋₁₈ akanol ethoxylates such as LUTENSOL® compounds available from BASF, as well as branched C₈₋₁₈ akanols such as EXXAL compounds available from EXXON.
Clay materials such as the low ion-exchange-capacity ones describerd in EPA 150.531 can also be used.
The co-softening agents above can be used in combination with cation-active amines, namely primary, secondary and tertiary amines having, at least, one straight-chain organic group of from 12 to 22 carbon atoms. Preferred amines of this class are ethoxyamines, such as monotallow-dipolyethoxyamine, having a total of 2to 30 ethoxygroups per molecule. Suitable are also diamines such as tallow-N,N', N'-tris (2-hydroxyethyl)-1,3-propylenediamine, or C₁₆₋₁₈-alkyl-N-bis(2-hydroxyethyl) amines, examples of above amines are these sold under the trade name GENAMIN C, S, D, and T, by Hoechst.
The co-softening agents above are used at ratios of from 5:1 of 20:1 of quaternary softening agent to co-softening agent.
In the instance for fatty acids are used, a preferred ratio is from 8:1 to 10:1.
Further other optional ingredients for use herein include silicone components such as described in British Patent No. 1,549,180, emulsifiers, preservatives, germicides, dyes, bactericides, stabilizers, brighteners, opacifiers, photoactivators, copolymeric carboxylates having sequestering properties, soil release agents, bleaches, bleach activators, and anti-yellowing agents. Suitable polymeric soil-release agents are disclosed in EP-A-220 156.
These additives are normally incorporated at their conventional low levels e.g. from 0.001% to 5%, in the dilution step of the concentrates herein.
The following examples illustrate the present invention.
The compositions of Example 1 and 2 were stored for 3 weeks at 50°C and compared with similar compositions not containing citric acid, stored under the same conditions; the compositions of Example 1 and 2 did not develop any perfume off-note, contrary to the reference compositions.