Non-chlorinated low alkalinity high retention cleaners

Abstract: Non-chlorinated, low alkalinity, high retention liquid hard surface cleaner concentrate and use solutions containing amine oxide surfactant, an anionic surfactant, a hydrophobically modified polymer surfactant, a thinner, and alkali are provided, which form viscous solutions upon dilution and which in cleaning operations, are capable of producing gel-like foams. The composition synergistically exhibits exceptional cleaning performance without the need of chlorine or high levels of caustic.

Description: The present invention pertains to the field of hard surface cleaners. More particularly, the invention pertains to hard surface cleaners which thicken upon dilution forming a gel-like foam during cleaning operations. In recent years, it has become increasingly desirable to utilize hard surface cleaners which have high viscosities to increase surface contact time, particularly on non-horizontal surfaces. Such liquid products are highly viscous compositions which are used as such, without dilution, or at most modestly diluted. Examples of such products are disclosed in U.S. Patent Nos. 3,622,391; 3,793,221; 3,843,548; and 4,005,027, and West German Patent DE 3,940,604. Most recently, attention has been focused upon the development of relatively low viscosity concentrates which thicken, or increase their viscosity, upon dilution to working concentrations. Such concentrates are cost effective due to their decreased packaging, transportation, and storage costs. Such concentrates are particularly useful for cleaning operations in the food industry. Several publications address thickening technology, for example H. Hoffmann, Progr. Colloid Polym. Sci. 84, pp 24-35 (1991); H. Hoffmann, Progr. Colloid Polym. Sci. 83 16-28 (1990); T. Imac and S. Ikada, Coll. and Pol. Sci. 13 134 (1985). Thickening technology is further described in European Patents EP 0 265 979, and EP 0 276 501; Great Britain Patent GB 2071688, and West German Patent DE 2359095. In European patent application EP 0 314 232 compositions are described which thicken upon dilution, and which contain a primary surfactant which may be, inter alia, an amine oxide surfactant or a co-surfactant thereof which may be anionic. However, these compositions, in order to perform their intended function, contain relatively large amounts of amine oxide surfactants, i.e. from 8 to greater than 18 weight percent in the concentrate. The concentrates are then diluted to form working solutions containing from 5 to 15 weight percent of the concentrate. Such compositions are not economical in view of the large concentration of surfactant required of both the concentrate and the working solution. Furthermore, both the final use viscosity as well as the cleaning efficiency is less than desirable. In order to compensate, chlorine bleaches must be added, raising environmental concerns. According to the present invention there is provided an aqueous chlorine-free concentrate suitable for dilution with water to form a viscous cleaning solution, comprising; (a) an amine oxide having the formula: wherein R is C 10 -C 18 alkyl and wherein each R 1 , independently, is selected from the group consisting of methyl, ethyl, and 2-hydroxyethyl; (b) an alkyl anionic surfactant selected from the group consisting of the ammonium and alkali metal salts of the alkyl sulfates, olefin sulfonates, alkylether sulfates, alkylaryl sulfonates, alkylarylether sulfates, alkylarylether sulfonates and mixtures thereof, wherein said alkyl groups are minimally C 12 when aryl groups are not present, and wherein said alkylaryl groups are minimally C 16 , and wherein said ether groups comprise a polyoxyalkylene group containing from 2 to 4 C 2 to C 4 alkylene oxide residues; (c) a hydrophobically modified polymer surfactant; (d) a thinner selected from the group consisting of methanol, ethanol, isopropanol propylene glycol methylether, dipropylene glycol methylether, and nonionic surfactants prepared by oxyalkylating an alkylphenol or fatty alcohol with from 4 to 10 C 2 -C 3 alkylene oxide moieties; and (e) an alkali, characterised in that the hydrophobically modified polymer surfactant is a hydrophobe-containing polyacrylate polymer. The aqueous concentrates of the present invention have relatively low viscosity but are also suitable for preparing viscous use solutions at low actives concentration. A further advantage of the aqueous concentrates of the invention is that upon dilution they develop into gel-like foams which enhance the residence time of the detergent solution on the surfaces to be cleaned, and which exhibit superior cleaning ability. Furthermore, the concentrates and use solutions of the present invention are free of chlorine and have low alkalinity so as to provide safe handling. The compositions of the present invention may further comprise chelating and/or sequestering agents, caustic soda or caustic potash, and comprise preferably a minor quantity of a thinner, which is either a solvent, a nonionic surfactant or both. The amine oxide surfactant used in the present aqueous concentrates corresponds to formula: where R is an alkyl group having from 10-18 carbon atoms, and each R 1 is, independently, methyl, ethyl, or 2-hydroxethyl. Preferably, R is from 12 to 16 carbon atoms, i.e. coconut, lauryl, or myristyl. Most preferably R is C 12 . Each R 1 is independently, preferably, methyl or 2-hydroxyethyl. The amount of amine oxide surfactant in the concentrate is preferably from 1 to 9 percent, by weight, of the total weight of the concentrate, more preferably, from 2 to 7 weight percent. The anionic surfactant is an alkali metal or- ammonium salt of an alkylsulfate, olefinsulfonate, alkylethersulfate, alkylarylsulfonate, alkylarylethersulfate, alkyl aryl ether sulfonates and mixtures thereof, wherein the alkyl group is minimally C 12 when aryl groups are not present, the alkylaryl group is minimally C 16 , and the ether groups comprise a polyoxyalkylene group containing from 2 to 4 C 2 to C 4 alkylene oxide residues. Preferably, the alkyl groups are straight chain alkyl groups. The amount of anionic surfactant is preferably from 1 to 8 percent by weight, more preferably, from 2 to 6 percent by weight relative to the total weight of the concentrate. Preferably, the chain length of the alkyl group of the anionic surfactant should be approximately equal to that of the amine oxide. The ratio of amine oxide surfactant to anionic surfactant ranges preferably from 4:1 to 1:4, preferably from 1.5:1 to 1:1.5. The hydrophobically modified polymer contains a hydrophobic portion and a hydrophilic portion. The hydrophobically-modified polymer surfactant is a hydrophobe-containing polyacrylate polymer, e.g. a co-polymer or a terpolymer of an acrylate or an acrylic acid, such as methylacrylate, methylmethacrylate, octyl acrylate and the like, alkokylated acrylates, alkyl alkoxylated acrylates, alkylaryl alkoxylated acrylates where the alkyl group was from 8 to 18 carbon atoms, and the alkoxy group is lower alkylene oxide, such as ethylene oxide, propylene oxide or butylene oxide, as well as mixtures of the aforementioned compounds. Preferred hydrophobically modified polymers are supplied by Rohm and Haas under the name ACUSOL TM . Preferred are ACUSOL TM 810 and ACUSOL TM 820. Likewise, the polymers supplied by Alco Chemical under the name Alcogum, such as the Alco SL and L series and, in particular, Alcogum SL-70 and Alcogum L-30 may be used. The amount of hydrophobically modified polymer is preferably from 1 to 5 percent, more preferably 2 to 4 percent, by weight, relative to the total weight of the concentrate. The chelating or sequestering agents suitable for use in the invention are the alkali metal salts of ethylenediamine tetraacetic acid (EDTA), nitrilotriacetic acid, and like compounds; anionic polyelectrolytes such as the polyacrylates, maleates, sulfonates and their copolymers, and alkali metal gluconates. Also suitable as chelating agents are the organophosphonates such as 1-hydroxyethylidene-1, 1-diphosphonic acid, amino (trimethylenephosphonic acid), hexamethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylene phosphonic acid), and 1,2-phosophonobutane-1,2,4-tricarboxylic acid. Such chelating agents are preferably used in the range of from 0.2 to 2.5 percent, by weight, and preferably 0.4 to 2 percent, by weight, relative to the weight of the concentrate. A solvent or non-ionic surfactant "thinner" is a necessary component of the subject invention. Among the solvents suitable as thinners are methanol, ethanol, isopropanol, propylene glycol methyl ether and dipropylene glycol methylether. Non-ionic surfactant thinners are alkylphenol oxyalkylates or fatty alcohol oxyalkylates containing from 4 to 10 oxyalkylene groups. Mixtures of these thinners are advantageously used. The amount of thinner ranges preferably from 1 to 5 percent, by weight, preferably 1.5 to 3.5 percent, by weight, relative to the total weight of the concentrate. An alkali is also a necessary part of the final composition. The alkali may be derived from soda ash, potash, sodium hydroxide, or potassium hydroxide. Calculated on the basis of a 50 weight percent solution of sodium hydroxide, the amount of alkali is preferably from 2 to 20 percent, more preferably from 8 to 12 percent, by weight, relative to the total weight of the concentrate. Thus, the final concentrate may contain, in percent by weight, the following components: Weight Percent Components Overall Preferable Amine oxide 1-9 3-8 Anionic surfactant 1-8 3-7 Hydrophobically modified polymer 1-5 2-4 Chelating agent 0.2-2.5 0.4-2 Thinner 1-5 1.5-3.5 Alkali 2-20 8-12 Water Remainder Remainder To prepare the concentrates of the subject invention, the ingredients are added to water one at a time and agitated until thoroughly mixed before addition of the next ingredient. In use, the concentrates of the subject invention are diluted to working concentrations of from 2 to 6 percent of the concentrate per total weight of the working solution. The following examples will further illustrate the preparation and performance of the preferred compositions in accordance with the present invention. However, it is to be understood that these examples are given by way of illustration and not limitation. In these example parts means parts by weight, unless otherwise noted. Example I A mixture of 82.9 parts water, 1.9 parts myristyl dimethylamine oxide, 0.4 parts octylphenoxy polyethoxy ethanol (HLB = 13.5), 1.5 parts sodium lauryl sulfate, 1.5 parts isopropyl alcohol, 3.8 parts Acusol-820, and 8.0 parts caustic soda 50 percent solution, was blended in a mixing vessel equipped with a suitable agitator. The ingredients were added one at a time and mixed thoroughly before each addition. The finished product was a transparent and homogeneous liquid concentrate. The Brookfield viscosity of a 10 percent solution was 500 cps (LV #2, 12 rpm). Example II A mixture of 78.1 parts water, 2.5 parts myristyl dimethylamine oxide, 0.5 parts octyl phenol ethoxylate (10 ethylene oxide groups), 2.5 parts isopropyl alcohol, 1.9 parts sodium lauryl sulfate, 3.5 parts Acusol 820, and 11.0 parts caustic soda 50 percent solution, was blended in the same manner as in Example 1. The finished product was a transparent and homogenous liquid concentrate. The Brookfield viscosity of 10 percent solution was 950 cps. (LV #2, 12 rpm) Example III A mixture of 77.1 parts water, 0.5 parts octylphenoxy polyethoxy ethanol (HLB = 13.5), 2.1 parts myristyl dimethylamine oxide, 1.8 parts sodium lauryl sulfate, 2.5 parts isopropyl alcohol, 2.0 parts Acusol 810, 3.0 parts Acusol 820, and 11.0 parts of a 50 percent caustic soda solution, was blended as described in the previous examples. The finished product was a viscous translucent and homogeneous liquid concentrate. The Brookfield viscosity of a 10 percent solution was 550 cps (LV #2, 12 rpm). Example IV A mixture of 73.4 parts water, 2.6 parts myristyl dimethylamine oxide, 2.1 parts sodium lauryl sulfate, 2.5 parts dipropylene glycol methyl ether, 0.9 parts polyacrylate (M.W. 4500), 4.5 parts Acusol 820, and 14.0 parts caustic soda, 50 percent solution, was blended as described previously. The finished product was a viscous, however, pumpable liquid concentrate. The Brookfield viscosity of a 10 percent solution was 2200 cps (LV #3, 12 rpm). Example V A mixture of 74.3 parts deionized water, 2.5 parts Dipropylene glycol methyl ether, 2.1 parts sodium lauryl sulfate, 2.6 parts myristyl dimethylamine oxide,- 2.0 parts Acusol 460N, 4.0 parts Acusol 820, and 12.5 parts caustic soda 50 percent solution, was mixed as previously described. The finished product was a clear, transparent and homogeneous liquid. The Brookfield viscosity of a 5% solution was 80 cps (LV #2, 30 rpm) and that of a 10 percent solution was 3400 cps (LV #3, 12 rpm). Example VI To the test the efficacy of the cleaners hereof it was necessary to first determine the gel retention strength, i.e. the degree of adherence to the surface to be cleaned. The gel strength or retention of cleaning chemicals adhering to surfaces can be tested by applying cleaners at working concentrations on stainless steel coupons (0.0762 m x 0.1524 m), allowing the excess solution to drain, and then weighing the coupons. The weight difference establishes the amount of cleaner solution adhered the to surface of the coupon. This indicates the difference in ability of cleaners to cling to the surface. Another test procedure that is quite reliable is viscosity measurement. In this method, the Brookfield viscosity measurement is done on a 10 percent w/w solution of samples to be tested at a specified temperature. The Brookfield Viscosity Procedure, generally involves the following steps: a. Prepare a 10 percent w/w of samples to be tested. b. Allow the test solutions to stand for 20 minutes to recover their viscosity. Since these solutions are thixotropic, they must be allowed to recover after being sheared through mixing. c. Adjust the temperature of test solutions to the same temperature at @ 22 - 25°C. d. Measure viscosity of the test solutions at exactly 10 seconds after the spindle has started. For the results from Brookfield Viscosity measurement to be reliable and reproducible, variables such as temperature, concentration, rest time, and measurement time must be controlled. Using the above Brookfield Viscosity Procedure, the cleaner concentrates of the examples hereof were tested for gel retention. The following sets forth the results of the tests. Test Results on Gel Retention Thickening Technology Brookfield Viscosity of a 10% w/w solution, cps Present Invention Example 1 500 (LV #2, 12 rpm) Example 2 950 (LV #2, 12 rpm) Example 3 550 (LV #2, 12 rpm) Example 4 2200 (LV #2, 12 rpm) Example 5 3400 (LV #3, 12 rpm) This result was, then, compared to a series of solutions from amine oxide-based concentrates and cationic-based cleaner concentrates. The formulation for amine oxide based compounds were as follows: Ingredient, amt. Cleaner 1 Cleaner 2 Cleaner 3 Water, soft 45.0 44.0 32.0 EDTA, sequestrant 5.0 6.0 Myristal dimethyl amine oxide 11.0 11.0 10.0 Sodium xylene sulfonate 6.0 4.0 8.0 Sodium lauryl sulfate 10.0 10.0 9.0 Caustic, 30% 20.0 16.0 Sodium hydroxide Potassium hydroxide 10.0 Sodium Silicate 11.0 1,2, phosphonobutane - 1.0 1,2,4 - tricarboxylic acid Sodium hypochlorite 24.0 dipropylene glycol methyl ether 3.0 4.0 The cationic-based concentrates are commercially available from Diversey Corp. as Shuregel 4 and 5, and are denoted CLEANER 4 and CLEANER 5, respectfully, below. The results of the tests were as follows: GEL RETENTION Cleaner Amine Oxide Based Brookfield Viscosity of a 10% w/w Solution, cps Cleaner 1 110 (LV #2, 30 rpm) Cleaner 2 60 (LV #2, 30 rpm) Cleaner 3 95 (LV #2, 30 rpm) Catonic-Based Cleaner 4 265 (LV #2, 30 rpm) Cleaner 5 160 (LV #2, 30 rpm) The data shows the excellent gel retention of the cleaners hereof when contrasted with the amine oxide-based and cationic-based. Example VII The present high retention cleaners were then tested for cleaning efficacy. The testing was conducted on a stainless steel panel (0.9144 m x 1.8288 m) using raw chicken as soil. The procedure used was as follows: a. Raw chicken, with skin on, was rubbed on the surface of a stainless steel coupon. b. The coupon was rinsed with cold water. c. A 5 percent w/w cleaning solution to be tested was prepared and transferred into a SHURFOAM 1401 tank. SHURFOAM 1401 is a foam applicator from Diversey Corp. which requires pre-dilution of cleaners. Cleaning solutions were applied by air pressure and foam consistency was adjusted. d. The foamed cleaner was sprayed on the soiled surface. e. The cleaner and soil on the surface was rinsed with cold water after 15 minutes. f. The sheeting effect and cleanliness on the surface was visually observed. Using a 3 percent w/w use solution of the concentrate of Example V a stainless steel panel was tested for cleaning using the above-defined procedure. It was observed that the soiled surface was absolutely cleaned. There was no sign of fat residues left on the surface. Rinsibility was excellent. Using a 5 percent w/w solution of the Cleaner 3 product, the outlined cleaning procedure was, again, repeated. It was observed that the soiled surface was quite clean. Only a few tiny fat spots on the surface. Rinsibility was very good. Using a sample of Cleaning 4, the test procedure outlined above was repeated. In this case, it was observed that the detergency was poor. Poor sheeting and soil were, also, noted. The amount of soil left on the surface was almost similar to the soiled surface prior to cleaning. From the above it is to be appreciated that the present cleaners exhibit good cleaning performance.

Claims: An aqueous chlorine-free concentrate suitable for dilution with water to form a viscous cleaning solution, comprising; (a) an amine oxide having the formula: wherein R is C 10 -C 18 alkyl and wherein each R 1 , independently, is selected from the group consisting of methyl, ethyl, and 2-hydroxyethyl; (b) an alkyl anionic surfactant selected from the group consisting of the ammonium and alkali metal salts of the alkyl sulfates, olefin sulfonates, alkylether sulfates, alkylaryl sulfonates, alkylarylether sulfates, alkylarylether sulfonates and mixtures thereof, wherein said alkyl groups are minimally C 12 when aryl groups are not present, and wherein said alkylaryl groups are minimally C 16 , and wherein said ether groups comprise a polyoxyalkylene group containing from 2 to 4 C 2 to C 4 alkylene oxide residues; (c) a hydrophobically modified polymer surfactant; (d) a thinner selected from the group consisting of methanol, ethanol, isopropanol, propylene glycol methylether, dipropylene glycol methylether and nonionic surfactants prepared by oxyalkylating an alkylphenol or fatty alcohol with from 4 to 10 C 2 -C 3 alkylene oxide moieties; and (e) an alkali, characterised in that the hydrophobically modified polymer surfactant is a hydrophobe-containing polyacrylate polymer. A composition according to claim 1, further comprising a chelating agent. A composition according to claim 2, wherein the chelating agent is selected from the group consisting of the alkali metal salts of ethylenediamine tetraacetic acid, nitrilotriacetic acid, polyacrylates, polymaleates, polysulfonates, co-polymers and terpolymers of the acrylates, maleates and sulfonates, as well as mixtures of the chelating agents. A composition according to claim 2, wherein the chelating agent is an organophosphonate chelating agent. A composition according to claim 4, wherein the organophosphonate chelating agent is selected from the group consisting of 1-hydroxyethylidene-1,1 diphosphonic acid, amino (trimethylenephosphonic acid), hexamethylenediaminetetra (methylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and 1,2-phosphonobutane-1,2,4-tricarboxylic acid. A composition according to any one of the preceding claims, wherein the amine oxide is present in an amount of from 1 to 9 weight percent; the anionic surfactant is present in an amount of from 1 to 8 weight percent; and the hydrophobically modified polymer surfactant is present in an amount of from 1 to 5 weight percent. A composition according to any one of the preceding claims, which, after dilution with water at a ratio of 1 part by weight of said composition to 9 parts water by weight, has a viscosity of 400 cps or more. A composition according to claim 7, wherein the said viscosity is 1000 cps or more. A process for cleaning hard surfaces, which process comprises (a) applying to a soiled surface a composition as claimed in any one of the preceding claims diluted with from 94 to 98 parts by weight of water; and (b) rinsing the said surface with water.

Inventors: RATANA KANLUEN
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1993
Main classification: C11D1
IPC codes: C11D1, C11D3