Patent Application
20080064618
The following description is of exemplary embodiments only and is not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and relative amounts of components described without departing from the scope of the invention as set forth in the appended claims.
The present invention relates to a composition for laundering fabrics that exhibits low sudsing and enhanced whiteness retention. The liquid laundry detergent compositions of the present invention include anionic surfactant components, preferably sulfonate and sulfate compounds, together totally from about 1.5-14%, nonionic surfactant from about 0.5% to about 5%, fatty acid soaps from about 0.05-2%, polyacrylate polymer from about 0.1-1%, and silicate from about 0.5-5%. In accordance with another exemplary embodiment, a liquid laundry detergent composition is provided with these components along with carbonate builder present at up to about 4%.
Anionic surfactants that are useful in the compositions of the present invention are the alkyl benzene sulfonates. Suitable alkyl benzene sulfonates include the sodium, potassium, ammonium, lower alkyl ammonium and lower alkanol ammonium salts of straight or branched-chain alkyl benzene sulfonic acids. Alkyl benzene sulfonic acids useful as precursors for these surfactants include decyl benzene sulfonic acid, undecyl benzene sulfonic acid, dodecyl benzene sulfonic acid, tridecyl benzene sulfonic acid, tetrapropylene benzene sulfonic acid and mixtures thereof. Preferred sulfonic acids, functioning as precursors to the alkyl benzene sulfonates useful for compositions herein, are those in which the alkyl chain is linear and averages about 8 to 16 carbon atoms (C8-C16) in length. Examples of commercially available alkyl benzene sulfonic acids useful in the present invention include Calsoft® LAS-99, Calsoft®°LPS-99 or Calsoft® TSA-99 marketed by the Pilot Chemical Company. Most preferred for use in the present invention is sodium dodecylbenzene sulfonate, most easily available by the in-situ neutralization of the above mentioned sulfonic acids with caustic (NaOH) in the compositions of the present invention, or available as the sodium salt of the sulfonic acid, for example Calsoft® F-90, Calsoft® P-85, Calsoft® L-60, Calsoft® L-50, or Calsoft® L-40. Also of use in the present invention are the ammonium salts, lower alkyl ammonium salts and the lower alkanol ammonium salts of linear alkyl benzene sulfonic acid, such as triethanol ammonium linear alkyl benzene sulfonate including Calsoft® T-60 marketed by the Pilot Chemical Company. The preferred level of sulfonate surfactant in the present invention is from about 0.5% to about 4%. Most preferred is to use dodecylbenzene sulfonic acid (LAS) at a level of from about 1% to about 3% (which will react in-situ to sodium dodecyl benzene sulfonate in the final composition).
Also with respect to the anionic surfactants useful in this composition, the alkyl ether sulfates, also known as alcohol ether sulfates, are preferred. Alcohol ether sulfates are the sulfuric monoesters of the straight chain or branched alcohol ethoxylates and have the general formula R—(CH2CH2O)x—SO3M, where R—(CH2CH2O)x— preferably comprises C7-C21 alcohol ethoxylated with from about 0.5 to about 9 mol of ethylene oxide (x=0.5 to 9 EO), such as C12-C18 alcohols containing from 0.5 to 9 EO, and where M is alkali metal or ammonium, alkyl ammonium or alkanol ammonium counterion. Preferred alkyl ether sulfates for use in one embodiment of the present invention are C8-C18 alcohol ether sulfates with a degree of ethoxylation of from about 0.5 to about 9 ethylene oxide moieties and most preferred are the C12-C18 alcohol ether sulfates with ethoxylation from about 1.5 to about 9 ethylene oxide moieties, with 7 ethylene oxide moieties being most preferred. It is understood that when referring to alkyl ether sulfates, these substances are already salts (hence “sulfonate”), and most preferred and most readily available are the sodium alkyl ether sulfates (also referred to as NaAES). Commercially available alkyl ether sulfates include the CALFOAM® alcohol ether sulfates from Pilot Chemical, the EMAL®, LEVENOL® and LATEMAL® products from Kao Corporation, and the POLYSTEP® products from Stepan, however most of these have fairly low EO content (e.g., average 3 or 4-EO). Alternatively the alkyl ether sulfates for use in the present invention may be prepared by sulfonation of alcohol ethoxylates (i.e., nonionic surfactants) if the commercial alkyl ether sulfate with the desired chain lengths and EO content are not easily found, but perhaps where the nonionic alcohol ethoxylate starting material may be. For example, sodium lauryl ether sulfate (“sodium laureth sulfate”, having about 3 ethylene oxide moieties) is very readily available commercially and quite common in shampoos and detergents, however, this is not the preferred level of ethoxylation for use in the present invention. For example it may be more practical to sulfonate a commercially available nonionic surfactant such as Neodol® 25-7 Primary Alcohol Ethoxylate (a C12-C15/7EO nonionic from Shell) to obtain the C12-C15/7EO alkyl ether sulfate that may have been more difficult to source commercially. The preferred level of C12-C18 alkyl ether sulfate with 1.5 to about 9 ethylene oxide moieties in the present invention is from about 1% to about 10%. Most preferred is a level of from about 3% to about 8%.
Most preferred for use in the compositions of the present invention is a mixture of both types of anionic surfactants described above. That is, it is preferable to incorporate both the linear alkyl benzene sulfonate and alcohol ether sulfate surfactants in the same compositions. Most preferable is to incorporate sodium dodecyl benzene sulfonate and a C12-C18 sodium alkyl ether sulfate with 0.5 to 9 ethylene oxide moieties together in the compositions of the present invention, and to incorporate a total sulfonate and alkyl ether sulfate level of from about 1.5% to about 14%, most preferably from about 2% to about 12%.
The compositions of the present invention preferably include nonionic surfactant. Nonionic surfactants are particularly good at removing oily soils from fabrics. Nonionic surfactants useful in the present invention include ethoxylated and/or propoxylated, primary alcohols having 10 to 18 carbon atoms and on average from 4 to 10 mol of ethylene oxide (EO) and/or from 1 to 10 mol of propylene oxide (PO) per mole of alcohol. Further examples are alcohol ethoxylates containing linear radicals from alcohols of natural origin having 12 to 18 carbon atoms, e.g., from coconut, palm, tallow fatty or oleyl alcohol and on average from 4 to about 9 EO per mole of alcohol. In formulating the liquid detergent composition of the present invention, nonionic surfactants of the alcohol ethoxylate type are useful since a proper HLB balance can be achieved between the hydrophobic and hydrophilic portions of the surfactant. Most useful as a nonionic surfactant in the present invention is the C14-C15 alcohol ethoxylate-7EO, mentioned above as a useful precursor to the corresponding sulfate, and at a preferred level of from about 0.5% to about 5%.
The fatty acids that find use in the present invention may be represented by the general formula R—COOH, wherein R represents a linear or branched alkyl or alkenyl group having between about 8 and 24 carbons. It is understood that within the compositions of the present invention, the free fatty acid form (the carboxylic acid) will be converted to the alkali metal salt in-situ (that is, to the fatty acid soap, or the more formally the “carboxylate salt”), by the excess alkalinity present in the composition. As used herein, “soap” means salts of fatty acids. Thus, after mixing and obtaining the compositions of the present invention, the fatty acids will be present in the composition as R—COOM, wherein represents a linear or branched alkyl or alkenyl group having between about 8 and 24 carbons and M represents an alkali metal such as sodium or potassium. The fatty acid soap, which is a desirable component having suds reducing effect in the washer, (and especially advantageous for side loading or horizontal tub laundry machines), is preferably comprised of higher fatty acid soaps. That fatty acids that are added directly into the compositions of the present invention may be derived from natural fats and oils, such as those from animal fats and greases and/or from vegetable and seed oils, for example, tallow, hydrogenated tallow, whale oil, fish oil, grease, lard, coconut oil, palm oil, palm kernel oil, olive oil, peanut oil, corn oil, sesame oil, rice bran oil, cottonseed oil, babassu oil, soybean oil, castor oil, and mixtures thereof. Fatty acids can be synthetically prepared, for example, by the oxidation of petroleum, or by hydrogenation of carbon monoxide by the Fischer-Tropsch process. The fatty acids of particular use in the present invention are linear or branched and containing from about 8 to about 24 carbon atoms, preferably from about 10 to about 20 carbon atoms and most preferably from about 14 to about 18 carbon atoms. Preferred fatty acids for use in the present invention are tallow or hydrogenated tallow fatty acids. Preferred salts of the fatty acids are alkali metal salts, such as sodium and potassium or mixtures thereof and, as mentioned above, preferably the soaps generated in-situ by neutralization of the fatty acids with excess alkali from the silicate. Other useful soaps are ammonium and alkanol ammonium salts of fatty acids, with the understanding that these soaps would necessarily be added to the compositions as the preformed ammonium or alkanol ammonium salts and not neutralized in-situ within the compositions of the present invention, (in the instant invention, in-situ neutralization of the fatty acids will necessarily generate sodium or potassium salts, or mixtures thereof of the fatty acids, due to the presence of the silicate having excess alkali). The fatty acids that may be included in the present compositions will preferably be chosen to have desirable detergency and effective suds reducing effect. Of course, for compositions wherein foaming is desirable soap content is omitted or lowered or a lower fatty acid soap, e.g., sodium laurate, may be used instead, but this is not the preferred strategy for the compositions of the present invention where suds suppression is desired. Most preferably in the present invention is to add tallow fatty acid, such as EMERY® 536 FATTY ACID from Cognis, (which comprises a complicated distribution of C14-C18 saturated and unsaturated fatty acids) at a level of from about 0.05% to about 2% and allow the fatty acids to neutralize in-situ to the soap in the alkaline composition.
The compositions of the present invention contain one or more silicate substances to reverse the deleterious fabric-graying effects of the added fatty acids in the compositions. The preferred silicate is an alkali metal silicate salt (the alkali metal salts of silicic acid) with the sodium and potassium silicate salts being the most preferred. The alkali metal silicates that are useful may be in a variety of forms that can be described by the general formula M2O:SiO2, wherein M represents the alkali metal and in which the ratio of the two oxides varies. Most useful alkali metal silicates will have a SiO2/M2O weight ratio of from about 1.6 to about 4. These silicates provide alkalinity to the composition (and to the resulting laundry wash liquor) and this alkalinity is far in excess of what is required to neutralize the small amounts of added fatty acids in the compositions to their corresponding alkali metal salts (soaps). Preferred silicates include the Sodium Silicate Solutions from PQ Corporation, such as A®1647 Sodium Silicate Solution, a 46.8% active solution of sodium silicate having a SiO2/Na2O ratio of about 1.6. Also of use in the compositions of the present invention are the potassium silicates, such as the Kasil® products from PQ Corporation. For example, Kasil®1 Potassium Silicate Solution is of use in the present invention and is a 29.1% solution of potassium silicate having a SiO2/K2O ratio of about 2.5. It is preferable to use either sodium or potassium silicate at a level of from about 0.5% to about 5% in the compositions of the present invention.
The compositions of the present invention include a water-soluble polymer such as a polycarboxylate. Particularly suitable polymeric polycarboxylates are derived from acrylic acid, and this polymer and the corresponding neutralized forms include and are commonly referred to as polyacrylic acid, 2-propenoic acid homopolymer or acrylic acid polymer, and sodium polyacrylate, 2-propenoic acid homopolymer sodium salt, acrylic acid polymer sodium salt, poly sodium acrylate, or polyacrylic acid sodium salt. Preferred in the compositions of the present invention is sodium polyacrylate with average molecular weight from about 2,000 to 10,000, more preferably from about 4,000 to 7,000 and most preferably from about 4,000 to 5,000. Soluble polymers of this type are known materials, for example the sodium polyacrylates and polyacrylic acids from Rohm and Haas marketed under the trade name Acusol®. Of particular use in the present invention is the average 4500 molecular weight sodium polyacrylate and the preferred level for use in the composition is from about 0.1% to about 1%.
The compositions of the present invention preferably contain alkali metal carbonate builder at a level of from about 0.1% to about 4%. Most useful in the present invention is sodium carbonate, however potassium carbonate may be used as well. It is well known that sodium carbonate is available in several forms including an anhydrous form as well as three hydrated forms. The hydrated forms include monohydrate, heptahdrate and decahydrates. Any of the commercially available forms of sodium or potassium carbonate find use in the present invention.
Optional ingredients may include other anionic surfactants in addition to alkyl benzene sulfonate and the alkyl ether sulfates mentioned above, particularly for example alkyl sulfates. Additionally, other nonionic surfactants such as the amphoteric surfactants and alkylpolyglycoside surfactants may find use in the compositions of the present invention. Optional too are other builder components besides the silicates and carbonates mentioned previously, lending an additional source of alkalinity or hard water chelation such as borates, tetrasodium ethylenediamine tetraacetate-EDTA, phosphates, zeolite, NTA and the like, bleaching agents (oxygen or chlorine based), optical brighteners, dye fixatives, enzymes, binders, carrier materials and auxiliary ingredients, and minor amounts of perfumes, dyes, solvents, etc. (e.g. cationic surfactants, softening or antistatic agent, water, thickeners, emulsifiers, acids, bases, salt, polymer, bleach catalysts, peroxygen compounds, inorganic or organic absorbents, clays, surface modifier polymer, pH-control agents, other chelants, active salts, abrasives, preservatives, colorants, anti-redeposition agents, opacifiers, anti-foaming agents, cyclodextrines, rheology-control agents, vitamins, oils, nano-particles, visible plastic particles, visible beads, etc.).
With the necessary and optional ingredients thus described, exemplary embodiments of the liquid laundry detergent compositions of the present invention, with and without silicate, with each of the components set forth in weight percent, are shown as Formulations 1-5 in Table 1:
To demonstrate the effectiveness of the fatty acid in controlling the suds level of the compositions of the present invention, a foam height measurement was conducted for some of these formulations. The test method used was simply a visual evaluation of the foam height on the clear window of an HE washing machine. The window of the machine was marked off in 5 even spaces, with 5 representing the very top of the window. Foam heights are expressed as foam to these levels marked on the window, thus lower values are preferred and represent suds suppression. The results are shown in Table 2 demonstrate that formulas 1-3 are very low sudsings.
To demonstrate the whiteness retention when washing with the compositions of the present invention, the following wash conditions were used. Fabric swatches (3 in×3 in) were laundered four times repeatedly in the presence of large amounts of soil, namely 2.6 mL of synthetic sebum soils and 11 mL of clay soils in a 1-liter bath of wash liquor. This repeated soil-laden washing correlates to about 25-30 regular wash cycles for a normal white garment of similar fiber construction. Whiteness of the swatches is then measured spectrophotometrically versus an unwashed white swatch control and is represent as a percent (%) of the original. Differences of 0.5 or greater are visually significant. The results are shown in Table 3 for two types of fabric.
The table above shows the increase in whiteness maintenance for a formulation incorporating the silicate. It is believed that the silicate mitigates the deleterious effects of the added fatty acid soaps. Most striking is the difference in performance on polyester/cotton between Formulas 1 and 4, wherein the only difference between the two compositions is the presence of the silicate.
