STABLE BIODEGRADABLE FABRIC SOFTENING COMPOSITIONS CONTAINING LINEAR ALKOXYLATED ALCOHOLS

Abstract: Shelf-stable/biodegradable fabric softening compositions are provided comprising mixtures of a quarternary ammonium salt containing at least one ester linkage, a linear alkoxylated alcohol, and a liquid carrier. These biodegradable compositions have improved product stability and dispersability, as well as excellent fabric softening characteristics.

Description: The present invention relates to textile treatment compositions. In particular, it relates to textile treatment compositions for use in the rinse cycle of a textile laundering operation to provide fabric softening/static control benefits, the compositions being characterized by excellent storage stability and viscosity characteristics, as well as biodegradability. The compositions herein can also be used in hair conditioner compositions. BACKGROUND OF THE INVENTION Textile treatment compositions suitable for providing fabric softening and static control benefits during laundering are well-known in the art and have found wide-scale commercial application. Conventionally, rinse-added fabric softening compositions contain, as the active softening component, substantially water-insoluble cationic materials having two long alkyl chains. Typical of such materials are di-tallow di-methyl ammonium chloride and imidazolinium compounds substituted with two stearyl groups. These materials are normally prepared in the form of a dispersion in water. It is generally not possible to prepare such aqueous dispersions with more than about 10% of cationic materials without encountering intractable problems of product viscosity and stability, especially after storage at elevated temperatures, such that the compositions are unpourable and have inadequate dispensing and dissolving characteristics in rinse water. This physical restriction on softener concentration naturally limits the level of softening performance achievable without using excessive amounts of product, and also adds substantially to the costs of distribution and packaging. Accordingly, it would be highly desirable to prepare physically-acceptable textile treatment compositions containing much higher levels of water-insoluble cationic softener materials. It would also be desirable to have fabric softening compositions which are storage-stable, and also which are biodegradable. However, materials which may be biodegradable are often difficult to formulate as stable liquid compositions. It is an object of this invention to provide a storage-stable, biodegradable fabric softening composition. It is a further objective to provide such materials in the form of liquid products, including concentrates, suitable for use in the rinse cycle of a textile laundering operation. These and other objects are obtained using the present invention, as will be seen from the following disclosure. Cationic softener materials are normally supplied by the manufacturer in the form of a slurry containing about 70%-80% of active material in an organic liquid such as isopropanol, sometimes containing a minor amount of water (up to about 10%). Retail fabric softening compositions are then prepared by dispersion of the softener slurry in warm water under carefully controlled conditions. The physical form and dispersibility constraints of these industrial concentrates, however, are such as to preclude their direct use by the domestic consumer; indeed, they can pose severe processing problems even for the industrial supplier of retail fabric softening compositions. The use of various quaternized ester-amines as cationic fabric softening agents is known in the art. See, for example, EP-A-22 562 or U.S. Patent 4,339,391, Hoffmann, et al., issued July 13, 1982, for a series of quaternized ester-amines which function as fabric softeners. Various quaternized ester-amines are commercially available under the tradenames SYNPROLAM R FS from ICI and REWOQUAT R from REWO. Unfortunately, although quaternized ester-amines are believed to be rapidly biodegradable, they are more subject to hydrolysis than are conventional cationic softening agents (e.g., ditallow dimethyl ammonium chloride and analogs thereof) and hence can encounter hydrolytic stability problems upon prolonged shelf storage. The product stability and viscosity problems becoming increasingly more unmanageable in concentrated aqueous dispersions. Various solutions to the problems of preparing concentrated fabric softening compositions suitable for consumer use have been addressed in the art. See, for example, U.S. Patents 4,426,299, issued January 17, 1984, and 4,401,578, issued August 30, 1983, Verbruggen, which relate to paraffin, fatty acids and ester extenders in softener concentrates as viscosity control agents. European Patent 0,018,039, Clint, et al., issued March 7, 1984, relates to hydrocarbons plus soluble cationic or nonionic surfactants in softener concentrates to improve viscosity and stability characteristics. U.S. Patent, 4,454,049, MacGilp, et al., issued June 12, 1984, discloses concentrated liquid textile treatment compositions in the form of isotropic solutions comprising water-insoluble di-C₁₆-C₂₄ optionally hydroxy-substituted alkyl, alkaryl or alkenyl cationic fabric softeners, at least about 70% of the fabric softener consisting of one or more components together having a melting completion temperature of less than about 20°C, a water-insoluble nonionic extender, especially C₁₀-C₄₀ hydrocarbons or esters of mono- or polyhydric alcohols with C₈-C₂₄ fatty acids, and a water-miscible organic solvent. The concentrates have improved formulation stability and dispersibility, combined with excellent fabric softening characteristics. U.S. Patent 4,439,330, Ooms, issued March 27, 1984, teaches concentrated fabric softeners comprising ethoxylated amines. U.S. Patent 4,476,031, Ooms, issued October 9, 1984, teaches ethoxylated amines or protonated derivatives thereof, in combination with ammonium, imidazolinium, and like materials. The use of alkoxylated amines, as a class, in softener compositions is known (see, for example, German Patent Applications 2,829,022, Jakobi and Schmadel, published January 10, 1980, and 1,619,043, Mueller et al., published October 30, 1969, and U.S. Patents 4,076,632, Davis, issued February 28, 1978, and 4,157,307, Jaeger and Davis, issued June 5, 1979). U.S. Patent 4,422,949, Ooms, issued December 27, 1983, relates to softener concentrates based on ditallow dimethyl ammonium chloride (DTDMAC), glycerol monostearate and polycationics. In GB-A-2,007,734, Sherman et al., published May 23, 1979, fabric softener concentrates are disclosed which contain a mixture of fatty quaternary ammonium salts having at least one C₈-C₃₀ alkyl substituent and an oil or substantially water-insoluble compound having oily/fatty properties. The concentrates are said to be easily dispersed/emulsified in cold water to form fabric softening compositions. Concentrated dispersions of softener material can be prepared as described in EP-A-406 and GB-A-1,601,360, Goffinet, published October 28, 1981, by incorporating certain nonionic adjunct softening materials therein. A dilute solution for fabric softening and antistatic treatment as described in EP-A-159 920 can be prepared by incorporating alkoxylated fatty compounds as softener adduct. As can be seen, the various solutions to the specific problem of preparing fabric softening compositions in concentrated form suitable for consumer use have not been entirely satisfactory. It is generally known (for example, in U.S. Patent No. 3,681,241, Rudy, issued August 1, 1972) that the presence of ionizable salts in softener compositions does help reduce viscosity, but this approach is ineffective in compositions containing more than about 12% of dispersed softener, in as much as the level of ionizable salts necessary to reduce viscosity to any substantial degree has a seriously detrimental effect on product stability. It has now been discovered that the product stability and viscosity characteristics of concentrated fabric softener compositions containing quaternized ester- amine softening agents can be significantly improved, both at normal and higher temperatures, by the addition thereto of defined levels of certain linear alkoxylated (i.e., ethoxylated and/or propoxylated) alcohols. The value of the linear alkoxylated alcohols disclosed herein for enhancing the long term viscosity characteristics and stability of these cationic fabric softener compositions has hitherto not been recognized in the art. SUMMARY OF THE INVENTION The present invention relates to a shelf-stable/biodegradable fabric softening composition comprising: (a) from 11% to 25% by weight of a quaternized ester-amine softening compound having the formula and mixtures thereof; wherein each R substituent is a short chain C₁-C₆ alkyl or hydroxyalkyl group, or mixtures thereof; R¹ is or C₁₃-C₁₉ hydrocarbyl group; R² is a C₁₃-C₂₁ hydrocarbyl group and X⁻ is a softener compatible anion; (b) from about 0.1% to about 10% of a linear alkoxylated alcohol selected from the group consisting of the condensation products of C₈-C₁₈ linear fatty alcohols with from about 1 to 10 moles of ethylene oxide or propylene oxide, and mixtures thereof; and (c) at least 60% of a liquid carrier. While not intending to be limited by theory, it is believed that the ester moieties lend biodegradability to these softening compounds whereas the addition of a linear alkoxylated (i.e., ethoxylated and/or propoxylated) fatty alcohol to the fabric softening composition greatly reduces the ester hydrolysis rate of the softening compounds, thereby improving the composition's shelf stability. In fact, the linear alkoxylated fatty alcohol provides sufficient hydrolytic stability that the ester-amine softening compounds can be stably formulated as liquid compositions, under the conditions disclosed hereinafter. The desirable viscosity characteristics of these compositions allows them to be formulated as concentrates. Moreover, since the fabric softening compounds used in these compositions are cationic, these compositions provide not only fiber and fabric softness, but also anti-static benefits. The present invention encompasses liquid fabric softening and antistatic compositions, comprising at least 11% by weight of a fabric softening compound of the above-disclosed formula, a linear alkoxylated alcohol (preferably ethoxylated), a liquid carrier, e.g., water, preferably a mixture of a C₁-C₄ monohydric alcohol and water. Such liquid compositions are preferably formulated at a pH of from about 2.0 to about 5.0 to provide good storage stability. The preferred liquid compositions herein have the softening compound present as particles dispersed in the liquid carrier. The particles are preferably sub-micrometer size, generally having average diameters in the range of about 0.10-0.50 micrometers. In addition to enhancing the compositions' hydrolytic stability, the linear alkoxylated alcohol also stabilizes the dispersions against settling. Importantly, the liquid compositions herein are substantially free (generally, less than about 1%) of free (i.e., unprotonated) amines, since free amines can catalyze decomposition of the quaternized ester-amine softening compounds, on storage. If minor amounts of amines are present, they should be protonated with acid during the formulation of the compositions. Strong acids, such as H₃PO₄ and HCl, can be used for this purpose. The low viscosities exhibited by dispersions of particles of the softening compounds herein allow them to be formulated as water-dilutable fabric softener "high concentrates" which contain from about 11% to about 25% by weight of the fabric softener compound. Such high concentrates may be conveniently packaged in pouches, which can be diluted with water by the user to produce "single-strength" softeners (typically, 3-5% concentration of softener active). The invention also encompasses a method of softening fibers (including hair) or fabrics, or imparting an antistatic finish thereto, comprising contacting said fibers or fabrics with a composition of the above-disclosed type or its diluted form. All percentages, ratios and proportions herein are by weight, unless otherwise specified. DETAILED DESCRIPTION OF THE INVENTION The compositions of the present invention comprise a mixture of a quaternary amine fabric softening agent containing at least one ester linkage, a linear alkoxylated alcohol, and a liquid carrier. Quaternized Ester-Amine Softening Compound The present invention contains as an essential component from about 11% to about 25% of a quaternized ester-amine softening compound having the formula wherein each R substituent is a short chain (C₁-C₆, preferably C₁-C₃) alkyl or hydroxyalkyl group, e.g., methyl (most preferred), ethyl, propyl, hydroxyethyl, and the like, or mixtures thereof; R¹ is or a long chain C₁₃-C₁₉ hydrocarbyl substituent, preferably C₁₆-C₁₈ alkyl, most preferably straight-chain C₁₈ alkyl; R² is a long chain C₁₃-C₂₁ hydrocarbyl substituent, preferably C₁₃-C₁₇ alkyl, most preferably C₁₅ straight chain alkyl. The counterion X⁻ is not critical herein, and can be any softener-compatible anion, for example, chloride, bromide, methylsulfate, formate, sulfate, nitrate and the like. It will be understood that substituents R, R¹ and R² may optionally be substituted with various groups such as alkoxyl, hydroxyl, or can be branched, but such materials are not preferred herein. The preferred compounds can be considered to be mono- and di- ester variations of ditallow dimethyl ammonium chloride (DTDMAC) which is a widely used fabric softener. The above compounds used as the active softener and antistatic ingredient in the practice of this invention are prepared using standard reaction chemistry. For example, in a typical synthesis of a mono-ester variation of DTDMAC, an amine of the formula RR¹NCH₂CH₂OH is esterified at the hydroxyl group with an acid chloride of the formula R²C(O)Cl, then quaternized with an alkyl halide, RX, to yield the desired reaction product (wherein R, R¹ and R² are as defined in the present application). A method for the synthesis of a preferred mono-ester softening compound is disclosed in detail hereinafter. However, it will be appreciated by those skilled in the chemical arts that this reaction sequence allows a broad selection of compounds to be prepared. As illustrative, nonlimiting examples there can be mentioned the following quaternized mono-ester amines (wherein all long-chain alkyl substituents are straight-chain): [CH₃]₂[C₁₈H₃₇] ⊕ NCH₂CH₂OC(O)C₁₅H₃₁Br ⊖ [CH₃]₂[C₁₃H₂₇] ⊕ NCH₂CH₂OC(O)C₁₇H₃₅C1 ⊖ [C₂H₅]₂[C₁₇H₃₅] ⊕ NCH₂CH₂OC(O)C₁₃H₂₇Cl ⊖ [C₂H₅][CH₃][C₁₈H₃₇] ⊕ NCH₂CH₂CH₂OC(O)C₁₄H₂₉CH₃SO₄ ⊖ [C₃H₇][C₂H₅][C₁₆H₃₃] ⊕ NCH₂CH₂OC(O)C₁₅H₃₁Cl ⊖ [iso-C₃H₇][CH₃][C₁₈H₃₇] ⊕ NCH₂CH₂OC(O)C₁₅H₃₁l ⊖ Similarly, in a typical synthesis of a di-ester variation of DTDMAC, an amine of the formula RN(CH₂CH₂OH)₂ is esterified at both hydroxyl groups with an acid chloride of the formula R²C(O)Cl, then quaternized with an alkyl halide, RX, to yield the desired reaction product (wherein R and R² are as defined in the present application). A method for the synthesis of a preferred di-ester softening compound is disclosed in detail hereinafter. However, it will be appreciated by those skilled in the chemical arts that this reaction sequence allows a broad selection of compounds to be prepared. As illustrative, nonlimiting examples there can be mentioned the following (wherein all long-chain alkyl substituents are straight-chain): Since the foregoing compounds (both mono- and di- esters) are somewhat labile to hydrolysis, they should be handled rather carefully when used to formulate the compositions herein. For example, stable liquid compositions herein are formulated at a pH in the range of about 2.0 to about 5.0, preferably about pH 3.5 ± 0.5. The pH can be adjusted by the addition of a Bronsted acid. Examples of suitable Bronsted acids include the inorganic mineral acids, carboxylic acids, in particular the low molecular weight (C₁-C₅) carboxylic acids, and alkylsulfonic acids. Suitable inorganic acids include HCl, H₂SO₄, HNO₃ and H₃PO₄. Suitable organic acids include formic, acetic, methylsulfonic and ethylsulfonic acid. Preferred acids are hydrochloric and phosphoric acids. Synthesis of a quaternized mono-ester amine softening compound Synthesis of the preferred biodegradable, quaternized mono-ester amine softening compound used herein is accomplished by the following two-step process: Step A. Synthesis of Amine 0.6 mole of octadecyl ethanol methyl amine is placed in a 3-liter, 3-necked flask equipped with a reflux condenser, argon (or nitrogen) inlet and two addition funnels. In one addition funnel is placed 0.4 moles of triethylamine and in the second addition funnel is placed 0.6 mole of palmitoyl chloride in a 1:1 solution with methylene chloride. Methylene chloride (750 mL) is added to the reaction flask containing the amine and heated to 35°C (water bath). The triethylamine is added dropwise, and the temperature is raised to 40-45°C while stirring over one-half hour. The palmitoyl chloride/methylene chloride solution is added dropwise and allowed to heat at 40-45°C under inert atmosphere overnight (12-16 h). The reaction mixture is cooled to room temperature and diluted with chloroform (1500 mL). The chloroform solution of product is placed in a separatory funnel (4 L) and washed with sat. NaCl, dil. Ca(OH)₂, 50% K₂CO₃ (3 times) , and, finally, sat. NaCl. The organic layer is collected and dried over MgSO₄, filtered and solvents are removed via rotary evaporation. Final drying is done under high vacuum (33.33 Pa). ANALYSIS TLC (thin layer chromatography) : solvent system (75% diethyl ether: 25% hexane) Rf = 0.7. IR (CCl₄): 2910, 2850, 2810, 2760, 1722, 1450, 1370 cm⁻¹ ¹H-NMR (CDCl₃): δ2.1-2.5 (8H), 2.1 (3H), 1.20 (58H), 0.9 (6H) ppm (relative to tetramethylsilane = 0 ppm). Step B: Quaternization 0.5 mole of the octadecyl palmitoyloxyethyl methyl amine, prepared in Step A, is placed in an autoclave sleeve along with 200-300 mL of acetonitrile (anhydrous). The sample is then inserted into the autoclave and purged three times with He (2.17 MPa (16275 mm Hg/21.4 ATM.)) and once with CH₃Cl. The reaction is heated to 80°C under a pressure of 0.48 MPa (3604 mm Hg/4.7 ATM). CH₃Cl and solvent is drained from the reaction mixture. The sample is dissolved in chloroform and solvent is removed by rotary evaporation, followed by drying on high vacuum (33.33 Pa (0.25 mm Hg)). Both the C₁₈H₃₇ and C₁₅H₃₁ substituents in this highly preferred compound are n-alkyl. ANALYSIS TLC (5:1 chloroform:methanol) : Rf = 0.25. IR (CCl₄): 2910, 2832, 1730, 1450 cm⁻¹ ¹H-NMR (CDCl₃): δ4.0-4.5 (2H), 3.5 (6H), 2.0-2.7 (6H), 1.2-1.5 (58H), 0.9 (6H) ppm (relative to tetramethylsilane = 0 ppm). ¹³C-NMR (CDCl₃): δ172.5, 65.3, 62.1, 57.4, 51.8, 33.9, 31.8, 29.5, 28.7, 26.2, 22.8, 22.5, 14.0 (relative to tetramethylsilane = 0 ppm). Synthesis of a quaternized di-ester amine softening compound The preferred biodegradable, quaternized di-ester amine fabric softening compound used in the present invention may be synthesized using the following two-step process: Step A. Synthesis of Amine 0.6 mole of methyl diethanol amine is placed in a 3-liter, 3-necked flask equipped with a reflux condenser, argon (or nitrogen) inlet and two addition funnels. In one addition funnel is placed 0.8 moles of triethylamine and in the second addition funnel is placed 1.2 moles of palmitoyl chloride in a 1:1 solution with methylene chloride. Methylene chloride (750 mL) is added to the reaction flask containing the amine and heated to 35°C (water bath). The triethylamine is added dropwise, and the temperature is raised to 40-45°C while stirring over one-half hour. The palmitoyl chloride/methylene chloride solution is added dropwise and allowed to heat at 40-45°C under inert atmosphere overnight (12-16 h). The reaction mixture is cooled to room temperature and diluted with chloroform (1500 mL). The chloroform solution of product is placed in a separatory funnel (4 L) and washed with sat. NaCl, dil. Ca(OH)₂, 50% K₂CO₃ (3 times) , and, finally, sat. NaCl. The organic layer is collected and dried over MgSO₄ and filtered. Solvents are removed via rotary evaporation. Final drying is done under high vacuum (33.33 Pa (0.25 mm Hg)). ANALYSIS TLC (thin layer chromatography) : solvent system (75% diethyl ether: 25% hexane) Rf = 0.75. IR (CCl₄): 2920, 2850, 1735, 1450, 1155, 1100 cm⁻¹ ¹H-NMR (CDC1₃): δ 3.9-4.1 (2H), 2.1-2.8 (8H), 2.3 (3H), 1.25 (52H), 1.1 (6H), 0.8 (6H) ppm (relative to tetramethylsilane = 0 ppm). Step B: Quaternization 0.5 moles of the methyl diethanol palmitate amine from Step A is placed in an autoclave sleeve along with 200-300 mL of acetonitrile (anhydrous). The sample is then inserted into the autoclave and purged three times with He (2.17 MPa (16275 mm Hg/21.4 ATM.)) and once with CH₃Cl. The reaction is heated to 80°C under a pressure of 0.48 MPa (3604 mm Hg/4.7 ATM.) CH₃Cl for 24 hours. The autoclave sleeve is then removed from the reaction mixture. The sample is dissolved in chloroform and solvent is removed by rotary evaporation, followed by drying on high vacuum (33.33 Pa (0.25 mm Hg)). ANALYSIS TLC (5:1 chloroform:methanol) : Rf = 0.35. IR (CCl₄): 2915, 2855, 1735, 1455, 1150 cm⁻¹. ¹H-NMR (CDCl₃): δ4.5-5.0 (2H), 4.0-4.4 (4H), 3.7 (6H) 2.0-2.5 (4H), 1.2-1.5 (52H), 0.9 (6H) ppm (relative to tetramethylsilane = 0 ppm). ¹³C-NMR (CDCl₃): δ172.8, 63.5, 57.9, 52.3, 33.8, 31.8, 31.4, 29.6, 24.6, 22.6, 14.1 ppm (relative to tetramethylsilane = 0 ppm). Linear Alkoxylated Alcohol The present invention contains, as an essential component, from about 0.1% to about 10%, preferably from about 0.1% to about 3%, of a linear alkoxylated alcohol. The linear alkoxylated alcohol improves the chemical stability of the fabric softening composition by reducing the ester hydrolysis rate of the quaternized ester-amine softening compound contained therein. In addition, the linear alkoxylated alcohol improves the physical stability of such compositions by stabilizing the particulate dispersions of the softening compounds against settling. Linear alkoxylated alcohols useful in the present invention are selected from the group consisting of the condensation products of C₈-C₁₈ linear fatty alcohols with from about 1 to about 10 moles of ethylene oxide (most preferred) or propylene oxide and mixtures thereof (including linear ethoxylated-propoxylated alcohols). Examples of linear ethoxylated fatty alcohols of this type include Neodol 23-3 (the condensation product of C₁₂-C₁₃ linear alcohol with 3 moles ethylene oxide), Neodol 91-2.5 (the condensation product of C₉-C₁₁ linear alcohol with 2.5 moles ethylene oxide), Neodol 45-9 (the condensation product of C₁₄-C₁₅ linear alcohol with 9 moles of ethylene oxide), Neodol 45-7 (the condensation product of C₁₄-C₁₅ linear alcohol with 7 moles of ethylene oxide), Neodol 45-4 (the condensation product of C₁₄-C₁₅ linear alcohol with 4 moles of ethylene oxide), all of which are marketed by Shell Chemical Company, and Kyro EOB (the condensation product of C₁₃-C₁₅ linear alcohol with 9 moles ethylene oxide), marketed by The Procter & Gamble Company. Preferred are the condensation products of C₁₀-C₁₅ linear alcohols with from about 2 to about 5 moles of ethylene oxide, most preferred are the condensation products of C₁₂-C₁₃ linear alcohols with 3 moles ethylene oxide (e.g., Neodol 23-3). If desired, the compositions herein can further be stablized against settling by the use of standard non-base emulsifiers, especially nonionic emulsifiers. Such nonionics and their usage levels, have been disclosed in U.S. Patent 4,454,049, MacGilp, et al, issued June 12, 1984. Specific examples of nonionic emulsifiers suitable for use in the compositions herein include fatty acid esters of glycerol (preferably glycerol monostearate) and fatty alcohols (e.g., stearyl alcohol). The standard nonionic emulsifers, if used, are typically used at levels of from 0.1% to about 2.5% by weight of the composition. Mixtures of glycerol monostearate with a linear ethoxylated alcohol are particularly preferred. Liquid Carrier 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 88.9%, preferably from about 70% to 88.9% of the liquid carrier. Preferably, the amount of the C₁-C₄ monohydric alcohol in the liquid carrier is from about 5% to about 50% by weight of the quaternized ester-amine softening compound, the balance of the liquid carrier being water. The softening compounds used in this invention are insoluble in such water-based carriers and, thus, are present as a dispersion of fine particles therein. These particles are sub-micrometer in size and are conveniently prepared by high-shear mixing which disperses the compounds as fine particles. A method of preparation of a preferred dispersion is disclosed in detail in Examples I-IV hereinafter. Again, since the softening compounds are hydrolytically labile, care should be taken to avoid the presence of base, and to keep the processing temperatures and pH within the ranges specified hereinafter. Optional Ingredients Fully-formulated fabric softening compositions may contain, in addition to the rapidly biodegradable quaternary ester-amine compounds of the formula herein, linear alkoxylated fatty alcohol and liquid carrier, one or more of the following optional ingredients. Conventional quaternary ammonium softening agents The compositions of the present invention can further comprise a conventional di(higher alkyl) quaternary ammonium softening agent. The compositions herein can contain from 0% to about 25% (preferably from about 0.1% to about 10%) of the conventional di(higher alkyl)quaternary ammonium softening agent. By "higher alkyl", as used in the context of the quaternary ammonium salts herein, is meant alkyl groups having from about 8 to about 30 carbon atoms, preferably from about 11 to about 22 carbon atoms. Examples of such conventional quaternary ammonium salts include: (i) acyclic quaternary ammonium salts having the formula; wherein R₂ is an acyclic aliphatic C₁₅-C₂₂ hydrocarbon group R₃ is a C₁-C₄ saturated alkyl or hydroxyalkyl group, R₄ is selected from R₂ and R₃, and A is an anion; (ii) diamido quaternary ammonium salts having the formula: wherein R₁ is an acyclic aliphatic C₁₅-C₂₂ hydrocarbon group, R₂ is a divalent alkylene group having 1 to 3 carbon atoms, R₅ and R₈ are C₁-C₄ saturated alkyl or hydroxyalkyl groups, and A is an anion; (iii)diamido alkoxylated quaternary ammonium salts having the formula: wherein n is equal to from about 1 to about 5, and R₁, R₂, R₅ and A are as defined above; (iv) quaternary imidazolinium compounds having the formula: wherein R₁ = C₁₅-C₁₇ saturated alkyl, R₂ = C₁-C₄ saturated alkyl or H, Z = NH or O, and A is an anion. Examples of Component (i) are the well-known dialkyldimethylammonium salts such as ditallowdimethylammonium chloride, ditallowdimethylammonium methylsulfate, di(hydrogenated tallow) dimethylammonium chloride, dibehenyldimethylammonium chloride. Examples of Components (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 Varisoft® 222 and Varisoft® 110, respectively. Examples of Component (iv) are 1-methyl-1-tallowamino-ethyl-2-tallowimidazolinium methylsulfate and 1-methyl-1-(hydrogenated tallowamidoethyl)-methylsulfate. Free amines The liquid compositions herein should be substantially free (generally less than about 1%) of free (i.e. unprotonated) amines. Care should be taken that if minor amounts of these amines are used to enhance the dispersion stability of the compositions, they are protonated with acid during formulation, otherwise the free amines may catalyze decomposition of the biodegradable quaternary ammonium compounds during storage. Minor amounts of protonated amines, typically from about 0.05% to about 1.0%, namely primary, secondary and tertiary amines having, at least, one straight-chain organic group of from about 12 to about 22 carbon atoms may be used in the compositions of the present invention to enhance dispersion stability. Preferred amires of this class are ethoxyamines, such as monotallow-dipolyethoxyamine, having a total of from about 2 to about 30 ethoxy groups per molecule. Also suitable are diamines such as tallow-N,N', N'-tris (2-hydroxyethyl)-1,3-propylenediamine, or C₁₆-C₁₈-alkyl-N-bis(2-hydroxyethyl)amines. Examples of the above compounds are those marketed under the trade names GENAMIN R C, S, O and T, by Hoechst. Di-(higher alkyl) cyclic amine The compositions herein optionally comprise from 0% to about 25% (preferably from about 0.1% to about 10%) by weight of the composition of a di(higher alkyl) cyclic amine fabric softening agent of the formula: wherein n is 2 or 3, preferably 2; R₁ and R₂ are, independently, a C₈-C₃₀ alkyl or alkenyl, preferably C₁₁-C₂₂ alkyl, more preferably C₁₅-C₁₈ alkyl, or mixtures of such alkyl radicals. Examples of such mixtures are the alkyl radicals obtained from coconut oil, "soft" (non-hardened) tallow, and hardened tallow. Q is CH or N, preferably N. wherein T is O or NR₅, R₅ being H or C₁-C₄ alkyl, preferably H, and R₄ is a divalent C₁-C₃ alkylene group or (C₂H₄O) m , wherein m is from about 1 to about 8. Silicone Component The fabric softening compositions herein optionally contain an aqueous emulsion of a predominantly linear polydialkyl or alkyl aryl siloxane in which the alkyl groups can have from one to five carbon atoms and may be wholly or partially fluorinated. These siloxanes act to provide improved fabric feel benefits. Suitable silicones are polydimethyl siloxanes having a viscosity, at 25°C, of from 1 to 1000 cm²/sec., preferably from 10 to 120 cm²/sec. It has been found that the ionic charge characteristics of the silicone as used in the present invention are important in determining both the extent of deposition and the evenness of distribution of the silicone and hence the properties of a fabric treated therewith. Silicones having cationic character show an enhanced tendency to deposit. Silicones found to be of value in providing fabric feel benefits having a predominantly linear character and are preferably polydialkyl siloxanes in which the alkyl group is most commonly methyl. Such silicone polymers are frequently manufactured commercially by emulsion polymerization using a strong acid or strong alkali catalyst in the presence of a nonionic or mixed nonionic anionic emulsifier system. In addition to providing improved fabric feel benefits, the silicone components also improve the water absorbency of the fabrics treated with the softening compositions herein. The optional silicone component embraces a silicone of cationic character which is defined as being one of: (a) a predominantly linear di-C₁-C₅ alkyl or C₁-C₅ alkyl aryl siloxane, prepared by emulsion polymerization using a cationic or nonionic surfactant as emulsifier; (b) an alpha-omega-di-quaternized di-C₁-C₅ alkyl or C₁-C₅ alkyl aryl siloxane polymer; or (c) an amino-functional di-C₁-C₅ alkyl or alkyl aryl siloxane polymer in which the amino group may be substituted and may be quaternized and in which the degree of substitution (d.s.) lies in the range of from about 0.0001 to about 0.1, preferably from about 0.01 to about 0.075 provided that the viscosity at 25°C of the silicone is from 1 to 1000 cm²/sec. The fabric softening compositions herein may contain up to about 15%, preferably from about 0.1% to about 10%, of the silicone component. Thickening Agent Optionally, the compositions herein contain from 0% to about 3%, preferably from about 0.01% to about 2%, of a thickening agent. Examples of suitable thickening agents include: cellulose derivatives, synthetic high molecular weight polymers (e.g., carboxyvinyl polymer and polyvinyl alcohol), and cationic guar gums. The cellulosic derivatives that are functional as thickening agents herein may be characterized as certain hydroxyethers of cellulose, such as Methocel R , marketed by Dow Chemicals, Inc.; also, certain cationic cellulose ether derivatives, such as Polymer JR-125 R , JR-400 R , and JR-30M R , marketed by Union Carbide. Other effective thickening agents are cationic guar gums, such as Jaguar Plus R , marketed by Stein Hall, and Gendrive 458 R , marketed by General Mills. Preferred thickening agents herein are selected from the group consisting of methyl cellulose, hydroxypropyl methylcellulose, or hydroxybutyl methylcellulose, said cellulosic polymer having a viscosity in 2% aqueous solution at 20°C of from 15 to 75,000 g/(m·sec). Soil Release Agent Optionally, the compositions herein contain from 0% to about 10%, preferably from about 0.2% to about 5%, of a soil release agent. Preferably, such a soil release agent is a polymer. Polymeric soil release agents useful in the present invention include copolymeric blocks of terephathalate and polyethylene oxide or polypropylene oxide, and the like. A preferred soil release agent is a copolymer having blocks of terephthalate and polyethylene oxide. More specifically, these polymers are comprised of repeating units of ethylene terephthalate and polyethylene oxide terephthalate at a molar ratio of ethylene terephthalate units to polyethylene oxide terephthalate units of from about 25:75 to about 35:65, said polyethylene oxide terephthalate containing polyethylene oxide blocks having molecular weights of from about 300 to about 2000. The molecular weight of this polymeric soil release agent is in the range of from about 5,000 to about 55,000. Another preferred polymeric soil release agent is a crystallizable polyester with repeat units of ethylene terephthalate units containing from about 10% to about 15% by weight of ethylene terephthalate unit together with from about 10% to about 50% by weight of polyoxyethylene terephthalate units, derived from a polyoxyethylene glycol of average molecular weight of from about 300 to about 6,000, and the molar ratio of ethylene terephthalate units to polyoxyethylene terephthalate units in the crystallizable polymeric compound is between 2:1 and 6:1. Examples of this polymer include the commercially available materials Zelcon® 4780 (from Dupont) and Milease® T (from ICI). Highly preferred soil release agents are polymers of the generic formula: in which X can be any suitable capping group, with each X being selected from the group consisting of H, and alkyl or acyl groups containing from about 1 to about 4 carbon atoms. n is selected for water solubility and generally is from about 6 to about 113, preferably from about 20 to about 50. u is critical to formulation in a liquid composition having a relatively high ionic strength. There should be very little material in which u is greater than 10. Furthermore, there should be at least 20%, preferably at least 40%, of material in which u ranges from about 3 to about 5. The R¹ moieties are essentially 1,4-phenylene moieties. As used herein, the term "the R¹ moieties are essentially 1,4-phenylene moieties" refers to compounds where the R¹ moieties consist entirely of 1,4-phenylene moieties, or are partially substituted with other arylene or alkarylene moieties, alkylene moieties, alkenylene moieties, or mixtures thereof. Arylene and alkarylene moieties which can be partially substituted for 1,4-phenylene include 1,3-phenylene, 1,2-phenylene, 1,8-naphthylene, 1,4-naphthylene, 2,2-biphenylene, 4,4-biphenylene and mixtures thereof. Alkylene and alkenylene moieties which can be partially substituted include ethylene, 1,2-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexamethylene, 1,7-heptamethylene, 1,8-octamethylene, 1,4-cyclohexylene, and mixtures thereof. For the R¹ moieties, the degree of partial substitution with moieties other than 1,4-phenylene should be such that the soil release properties of the compound are not adversely affected to any great extent. Generally, the degree of partial substitution which can be tolerated will depend upon the backbone length of the compound, i.e., longer backbones can have greater partial substitution for 1,4-phenylene moieties. Usually, compounds where the R¹ comprise from about 50% to about 100% 1,4-phenylene moieties (from 0 to about 50% moieties other than 1,4-phenylene) have adequate soil release activity. For example, polyesters made according to the present invention with a 40:60 mole ratio of isophthalic (1,3-phenylene) to terephthalic (1,4-phenylene) acid have adequate soil release activity. However, because most polyesters used in fiber making comprise ethylene terephthalate units, it is usually desirable to minimize the degree of partial substitution with moieties other than 1,4-phenylene for best soil release activity. Preferably, the R¹ moieties consist entirely of (i.e., comprise 100%) 1,4-phenylene moieties, i.e., each R¹ moiety is 1,4-phenylene. For the R² moieties, suitable ethylene or substituted ethylene moieties include ethylene, 1,2-propylene, 1,2-butylene, 1,2-hexylene, 3-methoxy-1,2-propylene and mixtures thereof. Preferably, the R² moieties are essentially ethylene moieties, 1,2-propylene moieties or mixtures thereof. Inclusion of a greater percentage of ethylene moieties tends to improve the soil release activity of compounds. Surprisingly, inclusion of a greater percentage of 1,2-propylene moieties tends to improve the water solubility of the compounds. Therefore, the use of 1,2-propylene moieties or a similar branched equivalent is desirable for incorporation of any substantial part of the soil release component in the liquid fabric softener compositions. Preferably, from about 75% to about 100%, more preferably from about 90% to about 100%, of the R² moieties are 1,2-propylene moieties. The value for each n is at least about 6, and preferably is at least about 10. The value for each n usually ranges from about 12 to about 113. Typically, the value for each n is in the range of from about 12 to about 43. A more complete disclosure of these highly preferred soil release agents is contained in European Patent Application 185,427, Gosselink, published June 25, 1986. Viscosity Control Agents Viscosity control agents can be used in the compositions of the present invention (preferably in concentrated compositions). Examples of organic viscosity modifiers are fatty acids and esters, fatty alcohols, and water-miscible solvents such as short chain alcohols. Examples of inorganic viscosity control agents are water-soluble ionizable salts. A wide variety of ionizable 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. Calcium chloride is preferred. The ionizable 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 ionizable 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 about 20 to about 3,000 parts per million (ppm), preferably from about 20 to about 2,000 ppm, by weight of the composition. Bactericides Examples of bactericides used in the compositions of this invention include glutaraldehyde, formaldehyde, 2-bromo-2-nitropropane-1,3-diol sold by Inolex Chemicals under the trade name Bronopol®, and a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazoline-3-one sold by Rohm and Haas Company under the trade name Kathon® CG/ICP. Typical levels of bacteriocides used in the present compositions are from about 1 to about 1,000 ppm by weight of the composition. Other Optional Ingredients The present invention can include other optional components conventionally used in textile treatment compositions, for example, colorants, perfumes, preservatives, optical brighteners, opacifiers, fabric conditioning agents, surfactants, stabilizers such as guar gum and polyethylene glycol, anti-shrinkage agents, anti-wrinkle agents, fabric crisping agents, spotting agents, germicides, fungicides, anti-oxidants such as butylated hydroxy toluene, anti-corrosion agents, and the like. In the method of this invention, fabrics or fibers are contacted with an effective amount, generally from about 20 ml to about 200 ml (per 3.5 kg of fiber or fabric being treated), of the compositions herein in an aqueous bath. Of course, the amount used is based upon the judgment of the user, depending on concentration of the composition, fiber or fabric type, degree of softness desired, and the like. Typically, about 120 mls. of a 5% dispersion of the softening compounds are used in a 25 l laundry rinse bath to soften and provide antistatic benefits to a 3.5 kg load of mixed fabrics. Preferably, the rinse bath contains from about 25 ppm to about 100 ppm of the fabric softening compositions herein. The following examples illustrate the practice of the present invention but are not intended to be limiting thereof. EXAMPLE I A storage stable biodegradable fabric softening composition of the present invention is made as follows: 20 g of the biodegradable mono-ester amine softener compound and 5 g of isopropanol are mixed and heated to 80°C to form a fluidized "melt". 4.8 g of GMS and 2 g Neodol R 23-3 are then added to the melt to form a homogeneous molten mixture. The molten mixture is then poured into a 400 g water seat with high shear mixing. The water is preheated to 70°C, and 20 ppm blue dye and 100 ppm bronopol R added to the water prior to mixing. About 1 g of isopropanol is evaporated from the molten mixture before it is poured into the water. The dispersion is mixed for 25 minutes at 7000 rpm (Tekmar R high shear mixer). During mixing the temperature of the dispersion is maintained within 70-75°C by a cooling water bath. The pH is adjusted by the addition of 1 ml of 0.1N HC1. The resulting dispersion has a viscosity of 50 g/(m·sec) (at 25°C) and a pH of 4.0. The average particle size in the dispersion is 0.20 micrometer. EXAMPLE II A storage stable biodegradable fabric softening composition of the present invention is made as follows: 20 g of the biodegradable mono-ester amine softener compound and 5 g of isopropanol are mixed and heated to 75°C to form a fluidized "melt". 4 g of GMS and 4 g of Neodol R 23-3 are then added to the melt to form a homogeneous molten mixture. The molten mixture is then poured into a 365 g water seat with high shear mixing. The water is preheated to 70°C. 0.6 g of isopropanol is evaporated from the molten mixture before it is poured into the water. The dispersion is mixed for 20 minutes at 7200 rpm (Tekmar R high shear mixer). The pH is adjusted by the addition of 1 ml of 0.1 N HCl. The resulting dispersion has a viscosity of 48 g/(m·sec) (at 25°C) and a pH of 4.0. The average particle size is 0.17 micrometer. EXAMPLE III A storage stable biodegradable fabric softening composition of the present invention is made as follows: Ingredient Percent (wt.) (CH₃)₂-N⁺ -[CH₂CHOC(O)C₁₅H₃₁]₂Cl⁻ 4.5% Isopropanol 0.6% Glyceryl Monostearate (GMS) 1.2% Neodol R 23-3 0.3% Polydimethylsiloxane (PDMS) 0.1% 0.1 N HCl 0.25% Water Balance 18 g of the biodegradable di-ester amine softener compound and 2.4 g of isopropanol are mixed and heated to 75°C to form a fluidized "melt". 4.8 g of GMS and 1.2 g of Neodol R 23-3 are then added to the melt to form a homogeneous molten mixture. The molten mixture is then poured into a 375 g water seat with high shear mixing. The water is preheated to 70°C. The dispersion is mixed for 15 minutes at 7000 rpm (Tekmar R high shear mixer). After the dispersion cools down to about 30°C, 0.4 g of PDMS is added to the dispersion with low shear mixing (3000 rpm for 3 minutes). The pH is adjusted by the addition of 1 ml of 0.1 N HCl. The resulting dispersion has a viscosity of 88 g/(m·sec) (at 25°C) and a pH of 3.9. The average particle size in the dispersion is 0.19 micrometer. EXAMPLE IV A storage stable biodegradable concentrated fabric softening composition of the present invention is made as follows: Ingredient Percent (wt.) (CH₃)₂-N⁺ -[CH₂CHOC(O)C₁₅H₃₁]₂Cl⁻ 15% Isopropanol 2.5% Glycerol Monostearate (GMS) 1.0% Neodol R 23-3 0.5% CaCl₂ 0.06% 0.1 N HCl 0.25% Water Balance 30 g of the biodegradable di-ester amine softener compound and 5 g of isopropanol are mixed and heated to 75°C to form a fluidized melt. 2 g of GMS and 1 g of Neodol R 23-3 are then added to the melt to form a homogeneous molten mixture. The melt is then poured into a 165 g water seat with high shear mixing. The water is preheated to 60°C. The dispersion is mixed for 15 minutes at 7000 rpm (Tekmar R high shear mixer). 6 ml of 2% CaCl₂ aqueous solution is added to the dispersion during mixing to prevent the dispersion from gelling. During mixing the dispersion's temperature is maintained at about 60°C. The pH is adjusted by the addition of 0.5 ml of 0.1 N HCl. The resulting dispersion has a viscosity of 210 g/(m·sec) (at 25°C) and a pH of 3.8. The average particle size in the dispersion is 0.26 micrometers. In a convenient mode, this concentrated composition is packaged in a simple plastic pouch, which is opened and poured into 4X its volume of water prior to use to prepare a "single strength" softener composition, thereby saving on packaging and shipping costs, as well storage space. Typically, the liquid fabric softening compositions in the above examples are added to the rinse cycle of conventional washing machines. When multiple rinses are used, the fabric softening composition is preferably added to the final rinse. The amount added to the rinse cycle is generally from about 20 ml to about 200 ml (per 3.5 kg of fabric being treated) of the compositions of Examples I-III (and the diluted version of Example IV). In all of the above examples, substantially similar results are obtained when Neodol R 23-3 is replaced, in whole or in part, with Neodol R 45-9 (the condensation product of C₁₄-C₁₅ linear alcohol with 4 moles of ethylene oxide), Neodol R 45-7 (the condensation product of C₁₄-C₁₅ linear alcohol with 7 moles of ethylene oxide), Neodol R 91-2.5 (the condensation product of C₉-C₁₁ linear alcohol with 2.5 moles ethylene oxide), Neodol R 45-4 (the condensation product of C₁₄-C₁₅ linear alcohol with 4 moles of ethylene oxide), and Kyro R EOB (the condensation product of C₁₃-C₁₅ linear alcohol with 9 moles ethylene oxide). Similar results are obtained in Examples I and II when the biodegradable quaternary mono-ester amine softening compound is replaced, in whole or in part, with any of the following biodegradable quaternary mono-ester amine softening compounds: [CH₃]₂[C₁₈H₃₇] ⊕ NCH₂CH₂OC(O)C₁₅H₃₁Br ⊖ [CH₃]₂[C₁₃H₂₇] ⊕ NCH₂CH₂OC(O)C₁₇H₃₅C1 ⊖ [C₂H₅]₂[C₁₇H₃₅] ⊕ NCH₂CH₂OC(O)C₁₃H₂₇Cl ⊖ [C₂H₅][CH₃][C₁₈H₃₇] ⊕ NCH₂CH₂OC(O)C₁₄H₂₉CH₃SO₄ ⊖ [C₃H₇][C₂H₅][C₁₆H₃₃] ⊕ NCH₂CH₂OC(O)C₁₅H₃₁Cl ⊖ [iso-C₃H₇][CH₃][C₁₈H₃₇] ⊕ NCH₂CH₂OC(O)C₁₅H₃₁l ⊖ In Examples III and IV, similar results are obtained when the biodegradable quaternary di-ester softening compound is replaced, in whole or in part, with any of the following biodegradable quaternary di-ester softening compounds: Similar results are also obtained when isopropanol in the above examples is replaced, in whole or in part, with ethanol, propanol, butanol, or mixtures thereof and when HCl is replaced, in whole or in part, with H₃PO₄. Importantly, the above biodegradable compositions display excellent softening characteristics on both natural and synthetic fabrics, low viscosity at both normal and elevated temperatures, and good product stability and dispersibility, compared with compositions containing no linear ethoxylated alcohol.

Claims: A liquid fabric softening and antistatic composition comprising a quaternary ester-amine softening compound having the formula and mixtures thereof; wherein each R substituent is a C₁-C₆ alkyl or hydroalkyl group or mixtures thereof; R¹ is or a C13-C19 hydrocarbyl group; R² is a C13-C21 hydrocarbyl group; and X- is a softener compatible anion; and a liquid carrier, characterized in that the composition contains : (a) from 11% to 25%, by weight of said quaternized ester-amine softening compound (b) from 0.1% to 10% by weight, of a linear alkoxylated alcohol selected from the group consisting of the condensation products of C8-C18, preferably C10-C15, linear fatty alcohols, with from 1 to 10 moles, preferably from 2 to 5 moles , of ethylene oxide or propylene oxide, and mixtures thereof; and (c) at least 60 % of the liquid carrier A composition according to Claim 1 which contains from 0.1% to 3% of a linear ethoxylated alcohol selected from the group consisting of the condensation products of C₁₂-C₁₃ linear alcohols with 3 moles of ethylene oxide. A composition according to Claim 1 or Claim 2 wherein the liquid carrier comprises a mixture of a C₁-C₄ monohydric alcohol, or mixtures thereof, preferably isopropanol, together with water, the amount of the monohydric alcohol being from 5% to 50% by weight of the softening compound. A composition according to any one of Claims 1 to 3 which is formulated at a pH of from 2.0 to 5.0. A composition according to any one of Claims 1 to 4 wherein the softening compound is present as particles, preferably having an average diameter in the range of from 0.1 to 0.5 micrometers, dispersed in the C₁-C₄ monohydric alcohol and water mixture. A composition according to any one of Claims 1 to 5 which is substantially free of unprotonated amines. A composition according to any one of Claims 1 to 6 which additionally contains from 0.1% to 2.5% of a fatty acid ester of glycerol, preferably glycerol monostearate. A composition according to any one of Claims 1 to 7 wherein the quaternized ester-amine softening compound is A composition according to any one of Claims 1 to 7 wherein the quaternized ester-amine softening compound is A composition according to any one of Claims 1 to 9 which additionally contains from 20 to 3,000 ppm of a salt selected from the group consisting of calcium chloride, magnesium chloride, sodium chloride, potassium chloride, lithium chloride, and mixtures thereof. A composition according to any one of Claims 1 to 10 which additionally contains from 0.1% to 10% of a conventional di-(higher alkyl) quaternary ammonium softening agent. A method of softening or providing an antistatic finish to fibers or fabrics, which method comprises contacting said fibers or fabrics with an effective amount of a composition according to any one of Claims 1 to 11.

Inventors: CHANG, NIENYUAN JAMES
Applicants: THE PROCTER & GAMBLE COMPANY
Application year: 1988
Main classification: C11D1
IPC codes: A61K8, D06M13, D06M15, C11D1, C11D3, A61Q5