CA1095805A

CA1095805A - Thickened acid cleaner

Info

Publication number: CA1095805A
Application number: CA303,639A
Authority: CA
Inventors: Joseph V. Otrhalek; Robert E. Gansser
Original assignee: DIVERSEY Corp (THE)
Current assignee: DIVERSEY Corp (THE)
Priority date: 1977-05-25
Filing date: 1978-05-18
Publication date: 1981-02-17
Also published as: GB1602234A; NL7805696A; FR2392106A1; FR2392106B1; ZA782974B; BE867457A; AU520251B2; AU3641778A

Abstract

THICKENED ACID CLEANER

Abstract of the Disclosure A thickened acid cleaner concentrate composition comprising an aqueous phosphoric acid, an alcohol, or glycol ether, e.g., isopropyl, or mono methyl ether of ethylene glycol, a nonionic surfactant, an anionic surfactant and water is useful in cleaning vehicles such as railroad rolling stock equipment without subsequent neutralization.

Description

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Backg;round of the Invention 1 Field of the Invention This invention relates to a thickened acid cleaner composition and a method of applying the composition to obtain exterior cleaning of vehicles (such as railroad rolling stock) without subsequent neutralization of the acid.

2 Description of the Prior Art Use of acids in cleaning compositions is known. For instance, U. S. Patent 2,257)467 discloses a solidified acid composition for cleaning toilet bowls and the like wherein the composition consists of sodium silicate, water and hydro-chloric acid. Another acid cleaner is disclosed in U. S.
P~tent 3,271,319 wherein it is taught that stains can be removed from glass surfaces by the use of an acid cleaner con-sisting of water, hydrofluoric acid, a carboxymethylcellulose thickener and a small amount, usually less than 1 percent, of an alkyl sulfate or alkyl aryl sulfonate wetting agent.
A still more recent patent, U. S. Patent 3J622,~91, teaches removing aluminide coatings from cobalt base or nickel base superalloys by the use of a hydrofluoric acid and water compo-sition which permissibly includes a low foaming or nonfoaming wetting agent. It is further disclosed that the composition can be thickened by adding a condensation product of ethylene oxide with a molecular weight of 4000 and gum tragacanth.
However, the use of this composition requires a follow-up neutraliza~ion with an alkali solution followed by water rinsing.

~r lO9S805 U S. Patent 3,793,221 teaches the use of a thickened acid cleaner composition comprising an aqueous hydrochloric acid, an organic acid, a nonionic surfactant, an anionic surfactant and water as useful in cleaning vehicles.
Mineral acids have also been used in cleaning com-positions as a defoamer. This technique is illustrated in U. S. Patent 3,650,965 wherein the foaming qualities of non-ionic surfactants for food industry cleaning can be reduced by the use of an organic acid coupled with a mineral acid such as phosphoric acid, the acid component being more than the surfactan~ component.
It has also been known to clean transportation equipment such as trains, boxcars and the like by the use of an acid cleaner to remove siliceous soils followed by an alkaline cleaner to remove organic and oily soils then finally followed by water rinsing Summary of the Invention In accordance with this invention there is provided a thickened acid cleaner concentrate composition comprising:
(1) an aqueous phosphoric acid in an amount from about 7 to about 60 weight percent, (2) a compound selected from the group consisting of aliphatic alcohols, glycol ethers and mixtures tnereof in an amount from about 1 to about 6 weight percent,

(3) a nonionic surfactant in an amount from about 7 to about 23 weight percent, 109~;805 (~) an anionic surfactant in an amount from about 1 to about 7 weight percent and, (5) water in an amount from about 8~ to about 4, weight percent;
all weight percents being based on a total compo-sition, provided that said nonionic surfactant and said anionic surfactant when ta~en together constitute from about 10 to about 30 weight percent of said composition and said nonionîc surfactant constitutes from about 75 to about 90 weight percent of the combined weight of the nonionic and anionic sur~actants The concentrate when diluted with 1 to 2 parts of water per part of concentrate is used to remove siliceous and/or oily soils from metal vehicles without a subsequent alkaline rinsing by flowing on a continuous coat of the cleaner, allowing the cleaner to remain on the surface of the vehicle for a period of time followed by a simple rinsing with water under impingement force pressure.
Description of the Preferred Embodiment The phosphoric acid employed in this invention may be either the 75~0 or 100~ phosphoric acid. It is intended that this is the only acid employed in this composition. In view of regulatory restric ions regarding environmental control and waste plant treatment restrictions acids such as hydroch~oric, sulfuric and organic acids such as oxalic, tartaric or citric are prohibited. Accordingly, phosphoric arid is the preferred acid to be employed in this composition On a weight percent basis the acid cleaner of this invention will contain from about 7 to about 80 percent acid and more preferably the acid content will be from about 20 to~about ~0 weight percent.
The second component of the invented composition is selected from the group consisting of aliphatic alcohols, glycol ethers and mixtures thereof wherein the alcohols con-tain from one to four carbon atoms, the glycol portion of the glycol ether contains from two to nine carbon atoms and the alkyl portion of the glycol ether contains from''one to four carbon atoms. Among the alcohols contemplated are methyl, ethyl, n-propyl, isopropyl, n-butyl,' isobutyl, sec-butyl and tertiary butyl. The preferred alcohols are methyl, ethyl, and isopropyl alcohol The glycol ethers employed may be monomethyl, ethyl, n- and isopropyl, n- and isobutyl ethers of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, di-propylene glycol and tripropylene glycol. The preferred glycol ethers are the alkyl ethers of ethylene glycol The particular surfactants employed in the invented composition in addition to ha~ing a cleaning effect also exhibit unusual thickening properties for this composition.
Therefore the surfactants of this invention are doubly critical The nonionic surfactant is present in an amount from about 7 to about 2~ weight percent of the final composi-tion and more preferably in an amount from about L2 to 18 weight percent.

1095~0~

The nonionic surface active agents which are advan-tageously employed in the compositions of the invention are generally the polyoxyalkylene adducts of hydrophobic bases wherein the oxygen/carbon atom ratio in the oxyalkylene portion of the molecule is greater than 0 40. Those compo-sitions which are condensed with hydrophobic bases ~o provide a polyoxyalkylene portion having an oxygen/carbon atom ratio greater than 0 40 include ethylene oxide, butadiene dioxide and glycidol, mixtures of these alkylene oxides with each other and with minor amounts of propylene oxide, butylene oxide, amylene oxide, styrene oxide,and other higher molec-ular weight alkylene oxides. Ethylene oxide, for example, is condensed with the hydrophobic base in an amount suffi-cient to impart water dispersibility or solubility and surface active properties to the molecule being prepared The exact amount of ethylene oxide condensed with the hydro-phobic base will depend upon the chemical characteristics of the base employed and is readily apparent to those ofordinary skill in the art relating to the synthesis of oxyalkylene surfactant condensates.
Typical hydrophobic bases which can be condensed with ethylene oxide in order to prepare nonionic surface active agents include mono- and polyalkyl phenols, polyoxy-propylene condensed with a base having from about 1 to 6 carbon atoms and at least one reactive hydrogen atom, fatty acids, fatty amides and fatty alcohols. The hydrocarbon 109~805 ethers such as the benzyl or lower alkyl ether of the poly-oxyethylene surfactant condensates are also advanta~eously employed in the compositions of the invention.
Among the suitable nonionic surface active agents are the polyoxyethylene condensates of alkyl phenols having from about 6 to 20 carbon atoms in the alkyl portion and from about 5 to 30 ethenoxy groups in the polyoxyethylene radical The alkyl substituent on the aromatic nucleus may be octyl, diamyl, n-dodecyl, polymerized propylene such as propylene tetramer and trimer, isoctyl, nonyl, etc. The benzyl ethers of the polyoxyethylene condensates of monoalkyl phenols impart good properties to the compositions of the invention and a typical product corresponds to the formula:
C8Hl-~ ~ (OCH2CH2) l50CH2C~sH5 Higher polyalkyl oxyethylated phenols corresponding to the formula:
R

Rl ~ o( CH2CH2Cl) nH

wherein R is hydrogen or an alkyl radical having from about 1 to 12 carbon atoms, Rl and R2 are alkyl radicals having from about 6 to 16 carbon atoms and n has a value from about 5 to 30 are also suitable as nonionic sur~ace active agents.
A typical oxyethy~ated polyalkyl phenol is dinonyl phenol condensed with 1~ moles of ethylene oxide.
.

10958~;

Other suitable nonionic surface active agents are cogeneric mixtures of conjugated polyoxyalkylene compounds containing in their structure at least one hydrophobic oxy-alkylene chain in which the oxygen/carbon atom ratio does not exceed 0.40 and at least one hydrophilic oxyalkylene chain in which the oxygen/carbon atom ratio is greater than 0 40.
Polymers of oxyalkylene groups obtained from propylene oxide, butylene oxide J amylene oxide, styrene oxide, mixtures of suchoxyalkylene groups with each other and with minor amounts of polyoxyalkylene groups obtained from ethylene oxide, butadiene dioxide, and glycidol are illustrative of hydrophobic oxyalkylene chains having an oxygen/carbon atom ratio not exceeding 0 40. Polymers of oxyalkylene groups obtained from ethylene oxide, butadiene dioxide, glycidol, mixtures of such oxyalkylene groups with each other and with minor amounts of oxyalkylene groups obtained from propylene oxide, butylene oxide, amylene oxide and styrene oxide are illustrative of hydrophilic oxyalkylene chains having an oxygen/carbon atom ratio greater than 0.40.
Further suitable nonionic surface active agents are the polyoxyethylene esters of higher fatty acids having from about 8 to 22 carbon atoms in the acyl group and from about 5 to 30 ethenoxy units in the oxyethylene portion.

1~95805 .
Typical products are the polyoxyethylene adducts of tall oil, rosin acids, lauric, stearic and oleic acids and the like Additional non-îonic surface active agents are the polyoxyethylene condensates of higher fatty acid amines and amides having from about 8 to 22 carbon atoms in the fatty alkyl or acyl group and about 10 to 30 ethenoxy units in the oxyethylene portion. Illustrative products are coconut oil fatty acid amides condensed with about 5 to 30 moles of ethylene oxide Other suitable polyoxyalkylene nonionic surface active agents are the alkylene oxide adducts of higher aliphatic alcohols and thioalcohols having from about 8 to 22 carbon atoms inthealipha~ic portionandabout5 to30 inthe oxyalkylene portion Typical products are synthet~c fatty alcohols, such as n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, n-octadecyl and mixtures thereof condensed with 5 to 30 moles of ethylene oxide, a mixture of normal fatty alcohols condensed with 8 to 20 moles of ethylene oxide and capped with benzyl halide or an alkyl halide, a mixture of normal fatty alcohols cond~nsed with 5 to 30 moles of a mixture of ethylene and propylene oxides, a mixture of se~eral fatty alcohols condensed sequentially with 2 to 20 moles of ethylene oxide and 3 to 10 moles of propylene oxide, in either order; or a mixture of normal fatty alcohols condensed with a mixture of propylene and ethylene oxides~ in which the oxygen/carbon atom ratio is losssbs less than 0.~0 follo~ed by a mixture of propylene and ethylene oxides in which the oxygen/carbon atom ratio is greater than 0 40 or a linear secondary alcohol condensed with ~ to 30 moles of ethylene oxidej or a linear secondary alcohol condensed with a mixture of propylene and ethylene oxides, or a linear secondary alcohol condensed with a mixture of ethylene, propylene, and higher alkylene oxides.
Of the foregoing described nonionic surface active agents or surfactants, a particularly preferred group is the polyethylene oxide condensates of alkyl phenols, particularly those having an alkyl group containing from about 6 to 12 carbon atoms in either a straight chain or branch chain configuration with ethylene oxide, the ethylene oxide being present in arnounts equal to ~ to 2~ moles of ethylene oxide per mole of alkyl phenol. This group of surfact~ants is exemplified by octylpheno~ypolyethoxyethanol The second component of the surfactant system of this invented composition is an anionic surfactant which is present in an amount from about 1 to about 7 weight percen~
and more preferably in an amount from about 2 to about percent.
Anionic synthetic non-soap detergents can bebroadly described as organic sulfuric and sulfonic acid reaction products having in their molecular structure an al~yl radical containing from about 8 to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. (Included in the term alkyl is the alkyl portion of higher acyl radicals.) Important examples of the synthetic detergents which form a part of the preferred cornpositions of the present invention are those obtained by sulfating the higher alcohols (C8-Cl3 carbon atoms) produced by reducing the glycerides of tallow or coconut oil; alkyl benzene sulfonates, in which the alkyl group contains from about 9 to about 15 carbon atoms, includ-ing those of the types described in United States Letters Patent Nos. 2,220,099 and 2,477,~8~ (the alkyl radical can be a straight or branched aliphatic chain), alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; coconut oil fatty acid monoglyceride sulfates and sulfonates; sulfuric acid esters of the reaction product of one mole of a higher fatty alcohol (e.g , tallow or coconut oil alcohols) and about 1 to 6 moles of ethylene oxide; sulfuric acid and sulfonic acid esters of the reaction product of one mole of a higher fatty oil (e.g , coconut or castor oil) and about 1 to 6 moles of ethylene oxide; alkyl phenolethylene oxide ether sulfate with about 1 to about 10 units of ethylene oxide per molecule and in which the alkyl radicals contain from 8 to about 12 carbon atoms; the reaction product of fatty acids esterified with isethionic acid where, for example, the fatty acids are derived from coconut oil; fatty acid amide of a methyl tauride in which the fatty acids, for 1095~5 exam?le, are derived from coconut oil; and others known in the art, a num~er being specifically set forth in United States Letters Patent Nos, 2,486,921, 2,486,922 and 2,~96,278, While less preferred the sodium and potassium salts of the foregoing sulfonic and sulfuric acid and/or ester anionic surfactants can also be used, The foregoing anionic surfactants are further exemplified in McCutcheon's Deter~ents & Emulsifiers, 1972 Annual, Allured Publishing Corporation, Ridgewood, New Jersey, Particularly suited for the process and composition of this invention are the alkyl or aryl sulfonic acid anionic surfactants exemplified by a linear alkyl benzene sulfonic acid, When taken together in considering the foregoing nonionic and anionic surfactants, it is critical to ~he success of this invention that the total amount of surfactant present constitute from about 10 to about 30 weight percent of the total cleaner composition and that the noni.onic portion of the total surfactant portion be from about 75 to about 95 weight percent, The final component of the invented clean;ng com- .
position is water which is present in an amount from about 83 to about 4 percent by weight and preferably in an amount from about 80 to about 10 weight percent, In addition to the foregoing ingredients, as is well known in the detergent arts, to the cleaning cOmpGSitiOn can be added such things as dyes, perfumes, corrosion inhib-itors and the like which do not detract from the present, invention, 109S~S

The foregoing acid thickened cleaner concentrate composition is diluted with water at the point of use to obtain the final cleaning composition. This dilution is preferably about 2 parts of water for each part of cleaner;
however, dilution ratios of from about 1 part to about 8 parts of water per part of cleaner concentrate are satis-factory The compositions of this invention are prepared by standard well-known open kettle mixing techniques known in the industry, A convenient charge schedule for preparation of the composition at room temperature would be to charge the water to the vessel, add the alcohol, followed by the nonionic surfactant, then the anionic surfactant and finally the phosphoric acid Should it be desired to add other optional modifiers to the composition such as dyes, perfumes and inhibitors they can be added as !convenient durirlg the preparation of the composition.
The thickened acid cleaner concentrate after dilution is flowed onto the vehicle to be cleaned in an amount to obtain physical coverage of the vehicle so that a thin but continuous film is obtained No brushing, scrub-bing or other similar effort is required The cleaner is allowed to remain at least one minute and preferably five minutes, however, up to ~0 minutes is satisfactory when the vehicle is cleaned during cold weather. It is an advantage l~)9S805 of the present composition that even if the water component of the composition evaporates during the period or applica-tion the cleaner can still be successfully rinsed afterwards.
Rinsing is achieved by the use of water being sprayed on the vehicle with impingement force and is most conveniently achieved by simply passing the vehicle through the spray rinse. For locomotives a water delivery rate of 150 to 200 gallons per minute and at a pressure of 100 to 200 pounds per square inch is satisfactory. Preferably the rinse will be applied at an angle starting at one end of the locomotive and sweeping forward to the other end and then re~ersing the angle and sweeping backward to the point of beginning. While the type of vehicle being washed will dictate the type of equipment being used, the acid cleaner composition of this invention is suitable for trucks and trailers, busses, air-planes, railroad engines, boxcars, passenger cars, cabooses, off-road equipment and similar equipment The acid cleaner composition of this invPntion avoids many of the problems associated with prior art clean-ing compositions For instance, the previously used inert thickeners presented problems in removing the thicl~ener res;-due after the washing, contributed to dry down problems and the simple disposal problem of the thic~ener residue after it was removed from the c~eaned vehicle. Dry do~ of course refers to the drying of the cleaner film prior to lts re-moval. It is recognized o~ course that the acid cleaner can 109S80:;

be used with wa~er of any hardness in contrast to alkaline cleaners which are dependent upon a certain degree of water softness in order to obtain desirable effects, In contrast, the present composition with its novel arrangement of sur-factants has increased cleaning efficiency, requires no , alkaline treatment afterwards, avoids the physical handling problem of the inert thickener residues and additionally facilitates the removal of the organic and oily road soils from the water while the water is in the holding tanks and ponds prior to being discharged into the natural waterways.
The practice of this invention is illustrated by, but not limited by the examples given below, Unless other-wise noted all parts or percents are parts or percents respectively by weight, Example 1 To an open kettle mixing vessel was charged 51 parts of water followed by 2 parts of isopropyl alcohol, Then 12 parts of octylphenoxy polyethoxyethanol (TRITON X-10~ ~ a nonionic surfactant of the ethoxylated monohydric alcohol type was added, With continuing mixing 4,5 parts of linear alkyl benzene sulfonic acid anionic surfactant of the alkane sulfonate type (CALSOFT LAS-99~ was blended in, Finally ~0 parts of 75~ phosphoric acid was added. The completed thick-ened acid cleaner WaS then discharged from the mixing vessel, The foregoing concen,rate was diluted with 2volumes of water and stirred to obtain a uniform mixture, The acid cleaner composition was then applied to a dirty locomotive.
Approximately 3 gallons were applied to the locomotive. The cleaner was allowed to remain on the locomotive for approxi-mately 5 minutes, The locomotive was then rinsed by driving the locomotive forward through a fixed spray at a speed of 5 to 8 miles an hour and then reversing the locomotive and bringing it back through the fixed spr~ys once more so that the water was applied at two different angles, The water pressure and delivery rate was 200 gallons of water per minute at 200 pounds per square inch. When dry the loco-motive was uniformly clean, free of residual siliceous road soils and oily road soils, had no streaks or spots left from the washing and the painted surface was unaffected by the wash treatment, Example 2 ~n this example the cleaning effectiveness of the acid concentrate as prepared in Example 1 at various dilu-tions was compared. Laboratory cleaning of metal coupons was employed, The coupons soiled with oil were cleaned by flow-ing on the cleaner at the dilutions noted below. UpGn standing for 10 minutes the coupons were inspected for dry down, i,e., dryness due to evaporation of water, They were then rinsed and evaluated for cleaning. The cleaning or soil removal was rated on a scale of 0 to 10 with 10 being completely clean, A rating of less than 7 is considered unsatisfactory. The results are tabulated below:

1095~i Concentrated Cleaner Dry Down No Cleaning rat~ 9 Diluted 1:2 with water Dry Down No Cleaning rate 8 Diluted 1:4 with water Dry Down No - Cleaning rate 6

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A thickened acid cleaner concentrate composi-tion comprising:
(1) an aqueous phosphoric acid in an amount from about 7 to about 60 weight percent, (2) a compound selected from the group consisting of aliphatic alcohols, glycol ethers and mixtures thereof in an amount from about 1 to about 6 weight percent, (3) a nonionic surfactant in an amount from about 7 to about 23 weight percent, (4) an anionic surfactant in an amount from about 1 to about 7 weight percent, and (5) water in an amount from about 83 to about 4 weight percent:
all weight percents being based on the total composition, provided that the said nonionic surfactant and the said anionic surfactant when taken together constitute from about 10 to about 30 weight percent of said compo-sition and said nonionic surfactant con-stitutes from about 75 to about 90 weight percent of the combined weight percent of nonionic and anionic surfactants.

2. The composition of claim 1 wherein the ali-phatic alcohols contain from one to four carbon atoms, the glycol portion of the glycol ether contains from two to nine carbon atoms, and the alkyl portion of the glycol ether contains from one to four carbon atoms.

3. The composition of claim 1 wherein the alcohol is isopropyl alcohol.

4. The composition of claim 1 wherein the glycol ether is mono methyl ether of ethylene glycol

5. The composition of claim 1 wherein the nonionic surfactant is an alkyl or alkylaryl polyether alcohol.

6. The composition of claim 1 wherein the anionic surfactant is an alkyl or alkylaryl sulfonic acid.

7 The composition of claim 1 wherein said aqueous phosphoric acid is in an amount from about 20 to about 30 weight percent, said alcohol is in an amount from about 2 to about 4 weight percent, said nonionic surfactant is in an amount from about 12 to 18 weight percent, said anionic surfactant is in an amount from about 2 to about 3 percent and said water is present in an amount from about 64 to about 35 weight percent

8. A thickened acid cleaner composition comprising about 1 to 2 parts of water per part of the thickened acid cleaner concentrate composition of claim 1.

9. A method for cleaning metal vehicles soiled with siliceous and/or oily soils comprising:
(a) applying to the surface of said vehicle a continuous coat of the thickened acid cleaner composition of claim 8, (b) allowing said cleaner composition to remain on the surface of said vehicle for a period of about 1 to about 30 minutes, and (c) rinsing said vehicle twice with water applied with an impinging force so as to mechanically remove the siliceous and oily soil residues.