US3312624A - Stable alkali soluble surfactants - Google Patents

Description

United States Patent Ofifice 3,312,624 STABLE ALKALI SOLUBLE SURFACTANTS Jean Dupre, Levittown, Pa., and Richard C. Mansfield,

Cherry Hill, N.J., assignors to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Mar. 12, 1965, Ser. No. 439,473 17 Claims. (Cl. 252-135) This application is a continuation-impart of our application Ser. No. 195,966 which was filed on May 18, 1962, and has since been abandoned.

This invention relates to improvements in the art of cleaning objects, particularly those made of metal, glass, etc.

Broadly stated, the invention pertains to alkaline cleaning and, more particularly, to surfactants for use in alkaline metal cleaning baths.

An object of the invention is to improve the cleaning efiiciency of alkaline metal cleaners.

Other objects of the invention Will in part be obvious and will in part be disclosed hereinafter.

Alkaline cleaners are the most Widely used means in industry for cleaning metal, glass, certain plastics, etc. They are primarily used to prepare metals such as steel, brass, and copper for plating, painting, enameling, rustproofing, pickling, and other operations. Such preparation includes the removal of various types of soil such as cutting oils, grinding, buffing, stamping, and drawing compounds used in various metal forming operations, as well as rust preventatives, lubricating greases, and various forms of dirt. The alkaline cleaning solutions may be used for soaking, spraying, or electrolytic types of cleaning. Of these, the soaking or tank cleaning technique is most important because of its Widespread use in industry.

In the soaking method of cleaning, the article to be cleaned usually is dipped in or slowly transported through a hot alkaline solution with little or no agitation present. The cleaning formulations employed generally consist of between about 88 to 99 percent by weight of various alkalies, such as caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripo-lyphosphate, sodium orthosilicate, tetrapotassium pyrophosphate, and tetrasodium pyrophosphate, and from about 1 to 12 percent by weight of a surfactant. Previously, the most widely used surfactants for this purpose have been alkylaryl sulfonates and rosin soaps. Usually, the concentration of the cleaning formulations (alkali plus surfactant) in the tank or bath is maintained between 2 and percent of the cleaning solution, and the temperature of the bath is kept at about 80-100 C.

As oil, grease, and other soils are caused to be separated from the part being cleaned in the tank, a scum-like layer collects at the top of the bath. If the surfactant employed is not thoroughly soluble in the hot alkaline solution, it also will tend to accumulate in this surface layer. When the accumulation of scam in the surface layer becomes so great that it tends to coat the otherwise clean part as it is withdrawn from the bath, it becomes necessary to skim the soil and undissolved surfactant from the top of the tank. Each time this is done, a considerable amount of the surfactant is removed and, of course, this tends tolower the concentration of the effective cleaning agents in the bath to a point Where the operation of the bath becomes unsatisfactory much sooner than it other- 3,312,624 Patented Apr. 4, 1967 wise would if such losses could be minimized or eliminated. Another problem is the fact that, should the soil remain dispersed and thus not require skimming, the oiled-out surfactant on the surface Will be objectionable since it tends to contaminate the cleaned object as it is removed. One obvious solution to these problems is to employ only surfactants that are soluble in hot alkaline solutions.

In addition to (l) solubility in hot alkaline solutions, other important requisites of alkaline cleaners include (2) stability on solid caustic and other alkalies and (3) stability in highly alkaline solutions. It is also desirable that there be essentially no discoloration on solid caustic and other alkalies. No known prior art detergents, which are very effective metal cleaners, have all of the above listed important properties as Well. The present invention, by comparison, provides an extremely eflicient metal cleaner that possesses all of these characteristics to an unusually high degree.

The attainment of the above general objects and specific properties has been made possible through a unique process by which novel compositions have been prepared. The compositions may be defined as blends of about to of M and about 25 to 10% N Where M=the reaction product (and salts thereof) of R(CH CH O) H and polyphosphoric acid and N=R (CH CH O) R In the above formulas R and R =C :alkoxy groups or alkylphenoxy groups with C alkyl groups,

R =alkyl group of about 1 to 8 carbons, and

x and 1:5 to 25, respectively.

Only when the blends are formed from certain ratios of their components can a useful combination of the above-described properties be obtained. The results of fonrning these critical combinations are unobvious and unpredictable from mere knowledge of the properties of each component, for each ingredient has certain limitations which appear to indicate a lack of utility for the purpose desired. For example, the phosphated portion is highly soluble in hot alkaline solutions, and satisfactorily stable on alkali and in alkaline solutions, but is not an effective cleaner. By contrast, the alkyl-terminated portion is a highly effective cleaner and is stable, 'but is not sufiiciently soluble in built alkaline solutions. But, when blended together in accordance with the present invention, the end products are highly soluble in concentrated hot alkaline solutions, stable on alkali and in alkaline solutions, and very effective as a cleaning agent.

The use of the divalent phosphate terminating group in part M of the unique blends affords the desired solubility and stability factors in a satisfactory manner which is incapable of achievement by other anionic components such as the sulfated, sulfonated or carboxymethylated analogs of the phosphate component. For part N other types of non-ionic components also do not give the desired properties. Blends with unterminated non-ionics, such as alkylphenoxy polyethoxy compounds, have proven nnstable. Non-ionics terminated with amides or esters are not stable on caustic or in alkaline solutions and are of questionable value as cleaners. Only the blends terminated with an alkyl group (ether linkage) provide both stability on caustic and satisfactory detergency with adequate solubility.

Part M of the unique blend, it should be pointed out, is a novel phosphate ester made according to a novel process disclosed in co-pending application Ser. No. 255,173 which was filed on Jan. 31, 1963 by Richard C. Mansfield. (That application, incidentally, is a continuation-in-part of Ser. No. 195,952 which was filed on May 18, 19 62 and since abandoned.) Although not all of phosphate esters disclosed in those applications are useful in the present situation, a large number of them are. In any event, the contents of the specifications of both appli cations are incorporated herein by reference since they disclose in detail the process of making many products which are employed in the present invention.

In brief, the novel phosphate ester, M, which consists of at least 85% primary phosphate (i.e. monoester phosphate) components, is prepared by reacting from 5 acids with a phosphoric acid anhydride content correthe sponding to about 73 to 85 percent expressed as P 0 In Table I, which follows, data are given comparing the performance characteristics of the present inventive composition, those of the components of our novel blend, those of several commonly used and widely accepted surfactants, as well as those of prior art materials with chemical compositions that are somewhat analogous to the composition of the present invention. None of the compositions B to J, inclusive, show the desirable combination of properties represented by A, specifically, good detergency (greater than under test conditions), adequate solubility (i.e., soluble in greater than 5% hot caustic solution), and stability on solid caustic and in caustic solution.

TABLE I Solubility Max. Percent NaOH Detergency, Stability 3 on Stability 4 in Discoloration 5 Composition in which 1% Percent Solid NaOH Caustic Solution on Solid Surf. is Soluble Cleaning Caustic from -100 C.

11. 0 Very slight. 15.0 None. 0 Slight 4. 0 None. 0 Considerable.

4. 0 None. 5. 5 Considerable. 7. 7 Very slight. 6. 7 18.0

1 A=Blend of 8 parts Cs n @o-wmomomr 03H, and 2 parts D Sodium dodecylbenzene sulfonate.

@oomommm Tall oil soap.

I=A phosphated non-ionic surfactant prepared by the reaction of an octylphenoxy (polyethoxyhm etha- 1.101 a (1 P 0 by the procedure described in U.S. Patent 3,004,056.

I =A sodium dodecyl diphenyl ether disulfonatc.

K=A blank 1 Removal of mineral oil (Sun 150 Brightstock) from solvent precleaned steel panels. The panels are rotated for 5 minutes at 28 rpm. in a bath of 5% of a base (madeirorn 40% NaOH, 28.5% Na COa, 31.5% sodium metasilicate pentahydrate) and 0.1% active surfactant maintained at 82 0. Each value represents the average percent of clean area on both sides of 3 panels.

a Two (2) percent surfactant (active) was blended on crystal flake caustic and stored in open jars for 23 weeks at 60 C.; detergeney was evaluated before and after storage in order to determine stability.

4 One (1) percent surfactant (active) was stored in caustic solutions (5-10%) at C. for 2-3 weeks. The cloud point was measured before and after storage.

6 Two (2) percent surfactant (active) was blended on crystal flake caustic and stored at 25 C. in a sealed container for at least one week.

*Does not give a clear solution from (iii- C. in water (0% NaOH).

As indicated above, the compositions of the present invention are comprised of blends of 75-90% of M (the phosphorylated component) and 2510% of N (the alkyl-terminated component). These ratios are critical to 6 The table does not reflect it, but, after thestability tests were run, detergency tests were run again to see how much of an effect the exposure to caustic had upon the compositions detersive abilities. For example, the blend the successful [functioning of the present invention. With of components A, at the 80/20 ratio, showed no change less than percent of component N inadequate deterfrom substantially 75% cleaning after storage on solid gency is obtained. With more than percent of N caustic at C. for 2-3 weeks on a 0.1% active surfacthe solubility of the end product in builder solutions is tant basis. A blend of component A, at the /30 ratio, inadequate. Table II, which follows, shows the imporshowed 87% cleaning initially at 0.1% active surfactant. tance of having the ratio of M:N within the desig- 10 After storage on solid caustic at 60 C. for four weeks, nated limits. detergency was not significantly changed.

TABLE II Solubility Percent NaOH Components 1 Ratio in which 1% Detergeucy, Stability 3 on Stability 4 in Diseoloration 5 of Blen M:N Sm-iactant Percent Solid Caustic Caustic Soluon Solid M and N Gives Clear Cleaning tion Caustic Solution from 60 100 O.

100/0 15.0 30 Yes None. /10 12.2 54 Yes Very slight. 80/20 11.0 73 Yes Do. 70/30 4.0 74 Yes Do. 0 86 Yes Slight. 80/20 8.8 73 No Moderate. 80/20 11.0 73 Yes Very slight. 80/20 11.8 83 Yes Do. 80/20 11.5 77 Yes Do. 80/20 9.6 89 Yes Do. 80/20 13.7 57 Yes Do. 80/20 10.5 65 Yes Do. 80/20 7.0 2 Yes" Do. 80/20 8.6 33 Yes Do. 80/20 16.0 77 Yes. Do. 80/20 4.0 86 No Slight.

iA=Ca 11 O-(CH2CH: )10 a 2/Cs 17O-(C 2CHsO)mCHa B=CBH11 O-(CH2CHa )m 0aH2/CaHi1 --O-(CH2CH20)mH C=CaH11 O(CH2OHRO)I&P03H2/C8H17@O (CH2CH2O 16CHZ D=08H17 O-(CHaCHzOhaPOaHnIGEHi1 -O(CH2CHz0)1uCnH5 H E=CsH11 V O CH-, CH2 )1ePOaHz/CaHnQO-(CHzCHaOhaCLHn F=CaH11 O-(CH2CH2O)zaPO3H2/CsHi1--O(CH;;CH:0) CH G=CsHi1 '0(CH2CH20)IOPO3H2ICEHI7 -O-(CH2CHaO)wCHa H= eH1o 0-(0Ht0th0)Foam/001% o omomo)mon, v

I=C12H2s O-(CHaCHzO) POQH2ICmH25 O(CH1CH7O):CH3

.I=C12H2s O-(CHzCHzO)14FosHz/C12 25-O-(CH2CHzO)14CHa K=C4H9 L=l;-C1zH25NH(CH2CHgO)15FosHzlt-cuHz NH(CH2CH2 )15CH3 H See footnotes in Table I above. .D oes not give a clear solution from 60100 C. in water (0% NaOH).

, In the test for detergency in Table II, a value of 50 or As another example, note the blend of component B higher is considered acceptable. All the detergency values which lacks the alkyl-terminated portion and, therefore, represent tests made before the stability tests were run. 75 is outside the scope of the present invention. It shows a detergency value of 73 for its 80/20 ratio of components, which is acceptable. When the same composition was altered to a 70/30 ratio, and tested on a 0.1% active surfactant level, it detergency value was 93 before being tested on solid caustic. However, after one week of exposure at 60 C. to the caustic, the detergency value dropped to 42, showing clearly the importance of the alkyl-terminated portion of the composition.

Compositions which include components A, at the 100/0 ratio, and also I, J and L are examples of other materials which are outside the ranges of the compositions of the present invention. Each is shown to illustrate the unacceptable detergency or stability on caustic, or solubility in NaOH, which results if the proper formulation is not made as herein disclosed.

The novel compositions can be prepared by either of two procedures. In Method I the non-ionic phosphate and the non-ionic alkyl-terminated ether can be prepared separately and then blended together. In Method II the non-ionic surfactant and the non-ionic alkyl-terminated ether can be blended together first and then the blend is phosphated. Method II is preferred since it has the advantage of terminating by phosphati-on any hydroxyl groups remaining in the non-ionic alkyl-terminated ether. Substantially complete termination of hydroxyl groups by either alkyl groups or phosphate groups i essential for good stability of the product on solid caustic. When Method II is used, the mixture of non-ionics can be prepared, of course, by simply partially alkylating the nonionic surfactant.

When Method I is used, a mixture of 1 mol of the non-ionic surfactant and about 1 to about 2 mols of polyphosphoric acid is first heated to about 80-110 C. until the cloud point in caustic solution ceases to rise. A pre- 'ferred range is about 1.0 to 1.3 mols of polyphosphoric acid to 1 mol of non-ionic surfactant. The indicated mols of polyphosphoric acid is based upon the percentage of phosphoric acid anhydride, expressed a percent P in the polyphosphoric acid. A more complete disclosure as to the nature of Method I and the resultant products therefrom is set forth in co pending application Ser. No. 255,173 and its since abandoned parent application Ser. No. 195,952, both cited above. The phosphorylated product made in this first step of Method I is then, in step 2, mechanically blended with the non-ionic alkylterminated ether component which has itself been prepared by the Well-known reaction of an alkyl halide with a non-ionic surface-active material in the presence of a base.

In the preferred Method II, the non-ionic surfactant and the alkyl-terminated non-ionic surfactant are mixed together and the blend is phosphated with a polyphosphoric acid at 80-110" C. It is necessary, as in Method I, to use about 1-2 mols of the polyphosphoric acid for each hydroxyl equivalent present in the mix, with 11.3 mols being prefer-red. In both methods greater amounts of the polyphosphoric acid give darker products, and this is generally to be avoided particularly since they are unnecessary for complete termination. Lesser amounts result in incomplete termination and usually require prolonged heating to get the reaction to go to completion.

Optionally, small amounts of an oxidizing agent, such as hydrogen peroxide, can be added before the phosphation step to give lighter colored products, if desired. An additional option, instead of using an oxidizing agent, is to use a reducing agent such as hydrazine hydrate.

Illustrative of the practice of this invention are the following examples. It should be understood, of course, that they are merely explanatory and are not limiting. The true limits of the invention, and those within which we agree to be bound, are thoe defined by the claims which follow the examples, it being understood that there will be many optional modes of practicing our invention wfithout having to depart from the spirit and scope there- 0 8 Example I To 91.4 parts (0.10 m.) of 20% methylated OPE (p-t-octylphenol +16 mols ethylene oxide) was added with stirring 34.4 parts (0.20 m. as P 0 of Victor 115% ortho equivalent polyphosphoric acid. The temperature was raised to 100 C. and the mixture stirred for 7 hours at 100105 C. The cloud point was measured periodically in 14% aqueous sodium hydroxide solution. There was no further rise after the 7 hours, the cloud point being 69 C. The mixture was cooled and bottled.

Example II To 63.7 parts (0.10 m.) of p-t-butylphenol-E was added in a nitrogen atmosphere with stirring at 40 C. during 5 minutes 33.8 g. (0.20 m.) of Victor 115 ortho equivalent polyphosphoric acid. The mixture was heated to 105 C. during another 20 minutes and then stirred at 105-l10 C. for 1%. hours. There was no change in cloud point during the last hour of heating. The cloud point was 61 C. in 20% aqueous sodium hydroxide solution. The mixture was cooled and bottled.

Portions of this material were mechanically mixed with portions of the methyl ether of p-t-b-utylphenol-E in the desired ratios to evaluate alkali solubility, stability and cleaning of various soils from metal as previously described.

We claim:

1. A stable alkali-soluble surfactant consisting essentially of a blend of about percent to about 90 percent of a component M with about 25 percent to about 10 percent of a component N, where M is a surface-active composition, which contains upwards of primary phosphate esters, of the class consisting of the condensation product, and the salts of said product, of the reaction of and polyphosphoric acid, N is R (CH CH O) R R and R are members of the class consisting of alkoxy groups having from 10 to 15 C atoms in the alkyl portion thereof, and alkylphenoxy groups having 4 to 10 C atoms in the alkyl portion thereof,

R is a C to C alkyl group, and

x and 1 each is a number in the range of from about 5 to about 25; V the said phosphate ester, M, being prepared by reacting from about 0.6 mol to about 2.0 mols of polyphosphoric acid with each mol of said condensation product; and the said polyphosphoric acid being a mixture of phosphoric acids with a phosphoric acid anhydride content corresponding to about 73 to 85 percent expressed as P O 2. The surfactant of claim 1 in which M essentially is a divalent phosphate-terminated alkylphenoxypolyethoxy compound whose alkylphenoxy portion contains an alkyl group having 4 to 10 C atoms and whose polyethoxy portion contains 5 to 25 condensed ethylene oxide units; and N is a lower alkyl terminated alkylphenoxypolyethoxy compound whose alkylphenoxy portion contains an alkyl group having 4-10 C atoms, whose polyethoxy portion contains 5 to 25 condensed ethylene oxide units, and whose alkyl-terminated portion contains l-8 C atoms.

3. The surfactant of claim 1 in which M essentially is a divalent phosphate-terminated alkoxypolyethoxy compound whose alkoxy portion contains an alkyl group having 10-15 C atoms and whose polyethoxy portion contains 525 condensed ethylene oxide units; and N is a lower alkyl terminated alkoxypolyet-hoxy compound whose alkoxy portion contains an alkyl group having 10- 15 C atoms, whose polyethoxy portion contains 5 to 25 condensed ethylene oxide units, and whose alkyl-terminated portion contains 1-8 C atoms.

9 4. The surfactant of'claim 1 in which M by heating together the non-ionic surfactant R (CHgCHgO H with polyphosphoric acid to about 80-110 C. until the cloud point in caustic solution ceases to rise, and N is prepared by reacting an alkyl halide, R X, with in the presence of a base, the value for R being the same as the value for R, and the values for R, R and x being the same as in claim 1, and X is a halogen.

5. The process of manufacturing the surfactant defined by claim 1 in which the non-ionic surfactant R(CH CH O) H is blended with the non-ionic alkyl terminated ether R (CH CH O) R and the blend is then phosphated with the polyphosphoric acid.

6. The surfactant of claim 4 in which the polyphosphoric acid is used in quantities of between 1 and 2 moles of it for each mole of the non-ionic surfactant 7. The process of claim 5 in which the polyphosphoric acid is used in quantities of between about 1 and 2 mols of it for each mol of the non-ionic surfactant and the phosphorylation is carried out of about 80-110 C.

8. The surfactant of claim 4 in which a small amount of hydrogen peroxide is added before the phosphation step to provide lighter colored products.

9. The process of claim 7 in which a small amount of hydrogen peroxide is added before the phosphation step to provide lighter colored products.

10. The surfactant of claim 4 in which a small amount of hydrazine hydrate is added before the phosphation step to provide lighter colored products.

11. The process of claim 7 in which a small amount of hydrazine hydrate is added before the phosphation step to provide lighter colored products.

12. A cleaning composition consisting essentially of a mixture of about 88 to 99 percent by weight of an alkali metal salt from the class consisting of caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripolyphosphate, sodium orthosilicate, tetrasodium pyrophosphate and tetrapotassium pyrophosphate, and about 1 to 12 percent by weight of the surfactant of claim 1.

13. A cleaning composition consisting essentially of a mixture of about 88 to 99 percent by weight of an alkali metal salt from the class consisting of caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripolyphosphate, sodium orthosilicate, tetrasodium pyrois prepared at a temperature phosphate and tetrapotassium pyrophosphate, and about 1 to 12 percent by weight of the surfactant of claim 2.

14. A cleaning composition consisting essentially of a mixture of about 88 to 99 percent by weight of an alkali metal salt from the class consisting of caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripolyphosphate, sodium orthosilicate, tetrasodium pyrophosphate and tetrapotassium pyrophosphate, and about 1 to 12 percent by weight of the surfactant of claim 3.

15. A cleaning bath essentially consisting of an aqueous alkaline solution having dissolved therein a mixture of about 88 to 99 percent by weight of an alkali metal salt from the class consisting of caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripolyphosphate, sodium orthosilicate, tetrapotassium pyrophosphate and tetrasodium pyrophosphate, and at least about 1 to 12 percent by weight of the surfactant of claim 1.

16. A cleaning bath essentially consisting of an aqueous alkaline solution having dissolved therein a mixture of about 88 to 99 percent by weight of an alkali metal salt from the class consisting of caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripolyphosphate, sodium orthosilicate, tetrapotassium pyrophosphate and tetrasodium pyrophosphate, and at least about 1 to 12 percent by weight of the surfactant of claim 2.

17. A cleaning bath essentially consisting of an aqueous alkaline solution having dissolved therein a mixture of about 88 to 99 percent by weight of an alkali metal salt from the class consisting of caustic soda, sodium metasilicate, soda ash, trisodium phosphate, sodium tripolyphosphate, sodium orthosilicate, tetrapotassium pyrophosphate and tetrasodium pyrophosphate, and at least about 1 to 12 percent by weight of the surfactant of claim 3.

References Cited by the Examiner UNITED STATES PATENTS 1,970,578 8/1934 Sch-oeller et a1. 252-89 X 2,178,831 11/1939 Bruson 25289 X 2,213,477 9/1940 Sleindorff et a1. 25289 X 2,577,503 12/1951 Baird et a1 252-89 X 3,004,057 10/1961 Nunn et al. 252-89 X 3,033,889 5/1962 Chiddix et al. 25289 X OTHER REFERENCES Concise Chemical and Technical Dictionary, Bennett (1962), Chemical Pub. Co., NY. (2nd ed.) pp. 482 and 479 relied on.

LEON D. ROSDOL, Primary Examiner.

JULIUS GREENWALD, SAMUEL H. BLECH,

Examiners.

J. T. FEDIGAN, Assistant Examiner.

Claims (2)

1. A STABLE ALKALI-SOLUBLE SURFACTANT CONSISTING ESSENTIALLY OF A BLEND OF ABOUT 75 PERCENT TO ABOUT 90 PERCENT OF A COMPONENT "M" WITH ABOUT 25 PERCENT TO ABOUT 10 PERCENT OF A COMPONENT "N," WHERE "M" IS A SURFACE-ACTIVE COMPOSITION, WHICH CONTAINS UPWARDS OF 85% PRIMARY PHOSPHATE ESTERS, OF THE CLASS CONSISTING OF THE CONDENSATION PRODUCT, AND THE SALTS OF SAID PRODUCT, OF THE REACTION OF

12. A CLEANING COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE OF ABOUT 88 TO 99 PERCENT BY WEIGHT OF AN ALKALI METAL SALT FROM THE CLASS CONSISTING OF CAUSTIC SODA, SODIUM METASILICATE, SODA ASH, TRISODIUM PHOSPHATE, SODIUM TRIPOLYPHOSPHATE, SODIUM ORTHOSILICATE, TETRASODIUM PYROPHOSPHATE AND TETRAPOTASSIUM PYROPHOSPHATE, AND ABOUT 1 TO 12 PERCENT BY WEIGHT OF THE SURFACTANT OF CLAIM 1.