The present invention relates to ester quat compositions with good dispersibility at temperatures of 30°C or lower. The compositions should be of particular value in the formation of fabric softeners for use in laundering procedures.
Quaternary ammonium salts of alkanolamines esterified with an average of two fatty acid moieties per molecule, commonly referred to as ester quats, have found broad use as fabric softeners. One problem with the use of these compounds is that they are typically difficult to disperse in water or aqueous solutions at temperatures below about 40°C. This can make the preparation of formulations more difficult and expensive.
One attempt to address problems of ester quat dispersibility was made by
Despite the efforts that have been made, there is still a need for improved ester quat compositions that can be easily dispersed in water or aqueous solutions at low temperatures and that maintain the ability to act effectively as fabric softeners.
The present invention is directed to compositions that contain ester quats with good dispersibility at low temperatures. The compositions may be used as fabric softeners in laundry processes.
In its first aspect, the invention is directed to a fabric softener active composition, containing one or more ester quats of formula (I):
- wherein R1, R2 and R3 are hydrogen or a group C(O)R5;
- R5 is an alkyl or alkenyl group comprising 11 to 21 carbon atoms;
- A- is a fabric softener compatible anion;
- R4 is methyl or ethyl.
The fabric softener compatible anion A- is preferably methyl sulfate or ethyl sulfate and most preferably methyl sulfate. Group R4 is preferably methyl.
On a normalized weight percent basis, 33-38% of the ester quats are monoesters, i.e. R1 is a group C(O)R5 and R2 and R3 are hydrogen; 52-55% are diesters, i.e. R1 and R2 are a C(O)R5 group and R3 is hydrogen; and 7-12% are triesters, i.e. R1, R2 and R3 are a group C(O)R5. The normalized weight percent basis is the sum of the weights of monoesters, diesters and triesters.
The R5 groups can be derived from a pure fatty acid R5COOH or a mixture of fatty acids of formula R5COOH, where R5 is a branched or unbranched alkyl or alkenyl group and preferably is unbranched. Examples of suitable saturated fatty acids are palmitic acid and stearic acid. Examples of suitable monounsaturated fatty acids are oleic acid and palmitoleic acid. It is also preferred that the alkyl or alkenyl chains of group R5 in formula (I) have an average chain length of 15 to 17 carbon atoms. The average chain length is calculated on the basis of the weight fraction of individual fatty acids in the mixture of fatty acids. For branched chain fatty acids the chain length refers to the longest consecutive chain of carbon atoms.
The iodine value of the R5 groups, calculated for the free fatty acid R5COOH, is from 65 to 85, preferably from 65 to 75 and most preferably about 70. The iodine value is a measure of the degree of unsaturation of esterified fatty acid carbon chains, i.e., the amount of iodine in grams consumed by the reaction of the double bonds of 100 g of fatty acid. The iodine value can be determined by the method of ISO 3961. The R5 groups preferably have a polyunsaturation level of less than 10%. The iodine value range of R5 groups described herein provides liquidity and dispersibility at temperatures below 30 °C, as well as good softening performance. The combination of the range of monoester content and the iodine value is of particular importance. In the iodine range of 65 to 85 and in particular of 65 to 75, monoester values below about 33 wt% tend to result in compositions that are too viscous for convenient use in the procedures described herein and generally assume a paste-like structure. As diester values increase substantially above 55 wt%, dispersibility at temperatures below about 30 °C tends to decrease.
Preferably, the cis to trans ratio of the unsaturated bonds of R5 alkenyl groups is less than 12:1 and, more preferably, between 5:1 and 9:1.
The fabric softener active compositions should contain 10-25% of an alcoholic solvent such as ethanol, 2-propanol, glycerol, ethylene glycol, propylene glycol, dipropylene glycol or a C1-C4 alkyl monoether of ethylene glycol.
At a temperature of greater than 15 °C and up to at least 25 °C, the fabric softener active composition is in the form of a transparent liquid.
The ester quats according to formula (I) should preferably be present in fabric softening active compositions at a level above 50%. These fabric softener active compositions may be used combined with water and other components to form aqueous fabric softeners that can be used in the laundering of fabrics.
Liquid aqueous fabric softener compositions can be made by mixing the fabric softener active compositions described above with water or an aqueous solution at a temperature of 0-30 °C, preferably 5-25 °C and more preferably 15-25 °C. After mixing, the aqueous fabric softener compositions will typically have 2-30 % by weight of ester quats according to formula I. The fabric softening active composition or aqueous solution may also optionally include additives such as viscosity aids, preservatives, or thickeners. Fragrant aqueous fabric softeners may be made by including a perfume in the fabric softener active composition and then mixing this with an aqueous solution according to the procedure described above or by concurrently mixing fabric softening active composition and perfume with water or an aqueous solution.
As a fabric softener, the ester quat compositions described herein may be used either as a liquid aqueous fabric softener composition in the rinse cycle of washing machines or as a dryer activated composition that is added at the time that fabrics are tumble dried. In the latter case, the fabric softeners will generally be in the form of dryer sheets comprised of a substrate of non-woven material impregnated with an aqueous dispersion of the fabric softening active compositions described herein. Examples of substrate sheets include, but are not limited to, cellulose fibers or synthetic fibers, particularly polyester, nylon, or polypropylene fibers.
The ester quats of the present invention can be made by esterifying triethanolamine with free fatty acids or triglycerides, optionally in the presence of a solvent or catalyst. A molar ratio of fatty acid to amine of from 1.40:1 to 1.70:1, and preferably from 1.45:1 to 1.60:1, may be used. The reaction can be carried out at a temperature of from 90 to 220 °C. The most preferred molar ratio of fatty acid to amine is 1.50 to 1. The reaction can be stopped by cooling to a temperature below about 80°C. Water may be removed by distillation from the reaction mixture, optionally with a reduction of pressure.
The average fatty acid chain length and iodine value are important for achieving a combination of good performance and good dispersibility at temperatures of 5-30 °C. Fatty acids used in the esterification should have an average chain length of from 12-22 carbons and an iodine value of from 65 to 85, preferably from 65 to 75. They may be either synthetic or from a natural source such as, for example, tallow, canola, soybean or palm oil. Average chain length is calculated on the basis of the weight fraction of individual fatty acids in the mixture. The required iodine value can be obtained by using a fatty acid mixture of natural origin that already has the desired value, by mixing compositions of different iodine values or by partial hydrogenation of a fatty acid mixture or a triglyceride mixture having a higher iodine value. The cis-trans-ratio of double bonds of unsaturated fatty acid moieties is preferably between 5:1 and 9:1.
In a second step, the triethanolamine fatty acid esters are quaternized with a suitable quaternizing reagent such as dimethyl sulfate. The molar ratio of quaternizing reagent to amine should generally be from 0.90 to 0.97 and the reaction should be carried out at a temperature of from 60 to 100°C until the total amine value of the reaction mixture is in the range from 1 to 8 mg KOH/g. The total amine value is determined by non-aqueous titration with perchloric acid according to method Tf 2a-64 of the American Oil Chemists Society and is calculated as mg KOH per g sample.
Alcoholic solvent is added during or after the quaternizing reaction described above so that the final ester quat active composition has 10-25 % solvent by weight.
The fabric softening active compositions described above are mixed with water or an aqueous solution to form aqueous fabric softener compositions that may be used in laundering procedures. Effective mixing may take place at 5-30°C, preferably at 5-25°C and more preferably at 15-25 °C. Mixing may take place under conditions of low shear and in the absence of any other agents that promote dispersion. This will result in the formation of a liquid dispersion at the temperature at which mixing occurs, e.g., at 15-20°C. In contrast to the fabric softening active composition, the resulting aqueous fabric softener composition is in general opaque. Other ingredients that may be added to aqueous compositions include, but are not limited to, fragrances, preservatives, thickeners, dyes, and optical brighteners.
The compositions described herein can be used in a wide variety of cleaning procedures but it is believed that they will be of particular value in clothes washing procedures. Typically, these cleaning operations involve an initial step in which dirt is removed using detergents, followed by a rinse procedure in which detergent that has been applied is removed. It is in the latter, rinse step, that the compositions described herein would usually be used.
The fabric softening active compositions described above may be mixed with water or an aqueous solution and applied to a non-woven substrate to make a dryer activated sheet suitable for use in tumble dryers. Such dryer activated sheets are prepared by mixing fabric softening active compositions with water to form an aqueous dispersion, which is subsequently brought into contact with or applied to the substrate. The aqueous dispersion may optionally contain further ingredients including, but not limited to, nonflammable solvents, auxiliary surfactants, preservatives, viscosity aids, and fragrances.
The dryer activated sheets described above can be used after the washing and rinsing procedure during the drying cycle in tumble dryers. The dryer sheet is added to the tumble dryer along with damp laundry. During the drying cycle, the composition is distributed to the fabric to provide a softening and antistatic effect as well as optionally delivering fragrance and further active ingredients.
The invention is illustrated by the following nonlimiting examples.
All examples were carried out with triethanolamine ester quat fabric softener actives that were prepared by esterification of triethanolamine with fatty acid, followed by quaternization with dimethyl sulfate. The fabric softener actives contained ethanol as solvent unless specified otherwise. Fatty acids, their iodine value and fraction of polyunsaturated fatty acids, and molar ratios of fatty acid (FA) to triethanolamine (TEA) used for preparing the TEA ester quats are listed in table 1. The alcohol content, the normalized contents of monoester quat (MEQ), diester quat (DEQ) and triester quat (TEQ) as determined by NMR, and the appearance of the fabric softener actives are listed in table 2. The mixture of 50 wt-% oleic and 50 wt-% tallow fatty acid had a cis to trans ratio of olefinic bonds of about 7.
**Solvent is dipropylene glycol n-butyl ether
Deionized water is heated to 50 °C and stirred with an overhead mixer at 500 min-1. The fabric softener active, preheated to 50 °C and in a molten state, is added in a slow, steady manner. Calcium chloride as a 25 % active solution is added as necessary to maintain a defined vortex. Once the fabric softener active addition is complete, the dispersion is stirred at 50 °C for 10 minutes at 500 min-1, and then allowed to cool with continued stirring. Calcium chloride solution is added as necessary to control viscosity during the cooling period. Upon reaching 30 °C, optional ingredients such as fragrance, thickener, and preservatives may be added followed by an additional mixing time of 10 minutes. Final adjustments to viscosity are made by adding calcium chloride solution.
Deionized water is equilibrated to 25 °C and stirred with an overhead mixer at 500 min-1. The fabric softener active equilibrated to 25 °C is added in a slow, steady manner. Calcium chloride as a 25% active solution is added as necessary to maintain a defined vortex. Once the fabric softener active addition is complete, the dispersion is stirred at 25 °C for 10 minutes at 500 min-1. After mixing, optional ingredients such as fragrance, thickener, and preservatives may be added followed by an additional mixing time of 10 minutes. Final adjustments to viscosity are made by adding calcium chloride solution.
Table 3 summarizes the results that were obtained with products A to L following these fabric softener formulation procedures, using the dispersion temperatures and fabric softener active contents given. Actives contents indicated as target could not be reached, as the mixture gelled before all fabric softener active was added.
All references cited herein are fully incorporated by reference. Having now fully described the invention, it will be understood by those of skill in the art that the invention may be practiced within a wide and equivalent range of conditions, parameters and the like, without affecting the scope of the invention or any embodiment thereof.