US3705856A - Additives for alkali cleaning systems - Google Patents

Abstract

LOW FOAMING, COPPER CORROSION INHIBITING, ALL TEMPERATURE ADDITIVES FOR ALKALI CLEANING SYSTEMS CONSISTS OF: (A) A MIXTURE OF SEQUESTERING AGENTS, (B) A MIXTURE OF NONIONIC SURFACTANTS, (C) AN ANIONIC SURFACE ACTIVE AGENT AS A HYDROTROPE, AND (D) WATER. THESE ADDITIVES WHEN EMPLOYED IN TYPICAL USE SOLUTIONS EXHIBIT SYNERGISM IN REGARD TO LOW FOAM CHARACTERISTICS AND COPPER CORROSION INHIBITION.

Description

United States l atent O 3,705,856 ADDITIVES FOR ALKALI CLEANING SYSTEMS Ronald M. Sedliar, Grosse Ile, Otto T. Aepli, Southgate, and Perle N. Burkard, Wyandotte, Mich, assignors to BASF Wyandotte Corporation, Wyaudotte, Mich. No Drawing. Filed Sept. 1, 1970, Ser. No. 68,760 Int. Cl. Clld 7/06 US. Cl. 252-156 Claims ABSTRACT OF THE DISCLOSURE Low foaming, copper corrosion inhibiting, all temperature additives for alkali cleaning systems consists of: (a) a mixture of sequestering agents, (b) a mixture of nonionic surfactants, (c) an anionic surface active agent as a hydrotrope, and ((1) water. These additives when employed in typical use solutions exhibit synergism in regard to low foam characteristics and copper corrosion inhibition.

BACKGROUND OF THE INVENTION 1) Field of the invention The present invention relates to liquid additives for alkali cleaning systems. More particularly, the present invention relates to low foaming, copper corrosion inhibiting additives for caustic soda cleaning systems which are usable over a wide temperature gradient.

(2) Prior art The use of caustic soda-based systems or use solutions for cleaning in breweries, dairies and the like has long been known. Today, the trend in such industries dictate the use of automated cleaning-in-place (CIP) systems which has in turn rendered liquid caustic solutions a prominent and important product. In order to satisfactorily clean, these products must demonstrate detergency, low foam propagation, rinsability and inhibition of hardness precipitation, as well as copper corrosion inhibition in copper brew kettles and the like. Accordingly, the art has taught the incorporation of additives, such as suitable sequestering agents, e.g. sodium gluconate and ethylenediaminetetraacetic acid, wetting agents and the like into caustic soda C-I-P systems to provide efliective in situ cleaning.

However, these types of additives have limited use since they foam excessively in C-I-P systems and generally they are limited to the areas in which they may be used. For example, in connection with breweries because of variations in cleaning temperatures at the cellar, brew house and bottle wash stations, types of soil and construction equipment, e.g., copper kettles, each specific cleaning application requires a specific C-I-P system.

The present invention seeks to obviate this problem by providing an additive useful in liquid caustic C-I-P systems which is low foaming, non-corrosive to copper and capable of performing at a wide temperature variant thereby rendering it extremely useful in breweries and the like.

SUMMARY OF THE INVENTION The present invention resides in a liquid additive for use in liquid caustic cleaning systems. Broadly speaking, the liquid additive consists of an aqueous solution of: (a) a mixture of sequestering agents, (b) a mixture of nonionic surface active agents, and (c) a hydrotrope or solubilizing agent which is an anionic surface active agent.

In preparing a typical use solution containing from about 5,000 to 50,000 p.p.m. of caustic soda the additive is employed in an amount ranging from about 500 p.p.m. to 100,000 p.p.m.

Patented Dec. 12, 1972 For a more comprehensive discussion of the present invention reference is made to the following detailed description and examples thereof.

DESCRIPTION OF THE PREFERRED- EMBODIMENTS The present invention provides a novel liquid additive for liquid caustic soda cleaning systems, preferably, C-I-P systems, and novel use solutions prepared therefrom. As hereinbefore mentioned, the present additives consist of (a) a hydrotrope which is an anionic surfactant, (b) a mixture of sequestering agents,

(c) a mixture of nonionic surfactants, and

(d) water.

It has been found that this additive, which is more particularly described hereinafter, when employed in typical use solutions exhibits synergism in regards to both low foam characteristics and copper corrosion inhibition.

The hydrotrope or solubilizing agent as hereinbefore noted is anionic surfactant which is a phosphate ester, and more precisely an alkylphenol polyglycol ether phosphate.

This product which is more particularly described in US. Pat. No. 3,235,627, the disclosure of which is hereby incorporated by reference, is sold commercially by Rohm and Haas under the name Triton 11-66.

It should be noted that in the reference patent the hydrotrope is referred to as a phosphate ester of a hydroxylic organic compound. In its presently available commercial form, Triton H-66 is provided as a potassium salt of the phosphate ester as a 50% solids aqueous solution and is characterized by a viscosity of centipoises at 25 C., a specific gravity of 1.26, a pH of 8-10 in 5% aqueous solution and a freezing point of 20 C.

The mixture of sequestering agents contemplated for use herein consists of a mixture of (1) a,a',rx"-amil10 tris-(methyl phosphonic acid), a composition corresponding to the formula:

H: P O3H2-CHa-I ICHs-P 01-11, or the potassium or sodium salt thereof, and (2) an alkali metal salt of a sugar acid. By the term sugar acid, as used herein, is meant the fermentation acids as Well as the aldonic and dibasic acids produced from sugars by chemical oxidation. Representative of this class of acids are, for example, lactic acid, citric acid, gluconic acid, 2-ketogluconic acid, glucoheptonic acid, tartaric acid, arabonic acid, galactinic acid, saccharic acid, mucic acid, and the like.

Typical alkali metal salts of the sugar acids are, for example, sodium lactate, sodium citrate, potassium sodium tartrate, sodium arabonate, sodium gluconate, sodium galactonate, sodium Z-ketogluconate, potassium sodium saccharate, sodium mucate and sodium glucoheptonate as well as mixtures thereof. These compounds and their use as sequestering agents is more particularly described by Mehltretter et al., Industrial and Engineering Chemistry, v. 95, No. 12, December 1953, at page 2782, the disclosure of which is hereby incorporated by reference. In the practice of the present invention it is preferred to employ either sodium gluconate or sodium glucoheptonate as the salt of the sugar acid.

In preparing the present additive, the mixture of sequestering agents is prepared such that the weight ratio of alkali metal salt of sugar acid to a,a',a"-amino tris- (methyl phosphonic acid) or potassium or sodium salt thereof ranges from about 15:1 to 25:1 and preferably from about 18:1 to 22:1.

The mixture of nonionic surfactants contemplated for use herein consists of a mixture of (1) the ethoxylatcd and propoxylated adducts of ethylenediamine, such as described in US. Pat. No. 2,979,528, and (2) either an alkoxylated linear aliphatic alcohol or a polyoxyethylenepolyoxypropylene block copolymer, such as described in US. Pat. No. 2,674,619, or mixtures thereof.

It has been found that not all of the above-described nonionic surfactants can be employed herein, but rather only those which exhibit low foam characteristics can be used. Thus, the nonionic surfactants generally described in US. Pat. 'No. 2,979,528, the disclosure of which is hereby incorporated by reference, are restricted to those compounds corresponding to the formula:

having a total molecular weight of from about 900 to 7,800 and wherein is an integer sufficiently large to insure that the ethylene oxide present constitutes a maximum of about 10% by weight of the total molecular weight of the molecule.

These compounds, as are described in the reference patent, are prepared by the sequential addition of propylene oxide and ethylene oxide to ethylenediamine under suitable oxyalkylation conditions.

The alkoxylated linear aliphatic alcohol or ethoxylated linear aliphatic alcohol nonionic surfactants are prepared by the condensation reaction, in the presence of a suitable oxyalkylation catalyst, of ethylene oxide and the alcohol. Generally the alcohols have from about 10 to 20 carbon atoms. These surfactants, which are widely known and commercially available, generally comprise from about 20 to 80% by weight of ethylene oxide, based on the total molecular weight of the surfactant. Sometimes ethoxylated" aliphatic alcohols contain some propylene oxide as well as ethylene oxide when purchased in commercial form. The propylene oxide usually comprises no more than about 30% by weight of the total molecular weight of the product, but more may be present depending on the commercial source of the product. It is the ethylene oxide, though, that enhances the surface active properties of these compounds. Accordingly, as used herein and in the claims appended hereto, the term ethoxylated linear aliphatic alcohol includes the products which contain this minor component, propylene oxide.

The polyoxypropylene-polyoxyethylene block copolymers of U8. Pat. No. 2,674,619, the disclosure of which is hereby incorporated by reference, which are suitable for use herein are those compounds corresponding to the formula:

having a molecular weight of from about 900 to 4,500 and wherein a+c are sufficiently large such that the ethylene oxide comprises from about to of the total molecular weight of the compound. These compounds are generally prepared by the condensation reaction of ethylene oxide and polypropylene glycol, polypropylene glycol being, in turn, the condensation reaction product of propylene oxide and propylene glycol.

In the practice of the present invention the mixtures of nonionic surfactants are prepared or utilized in a weight ratio of (1) to (2) ranging from about 2:1 to 1:2. Preferably a weight ratio of 1:1 is employed in preparing and utilizing the mixture.

In preparing the present additives composition, the ingredients thereof are combined in approximately the following weight proportions; based on 100 parts thereof:

4 Ingredients: Parts by weight Hydrotrope 1.0 to 9.0 1st sequestering agent 0.5 to 3.0 2nd sequestering agent 6.5 to 45.0 1st nonionic surfactant 0.5 to 5.0 2nd nonionic surfactant 0.5 to 5.0 Water 91.0 to 33.0

Thus, it is seen that the present additives consist of (a) from about 1 to 9 percent by weight of hydrotrope, (b) from about 7 to 48 percent by weight of the mixture of sequestering agents,

(c) from about 1 to 10 percent by weight of the mixture of nonionic surfactants, and (d) from about 33 to 91 percent by weight of water.

The additive is prepared by simply mixing the ingredients together, maintaining the hereinbefore described proportions and Weight ratios, at ambient conditions, i.e., room temperatures and pressures, no special handling procedures are necessary.

In preparing a typical use solution employing the present additives, all that is required is the simple addition of the additive to the use solution, with mixing. Generally, a caustic soda use solution will consist of (a) from about 5,000 to 50,000 parts per million (p.p.m.) of liquid caustic, (b) from about 500 to 100,00 ppm. of additive, and (c) the balance being water.

The present additives can also be directly incorporated into a liquid caustic wherein they will be present in an amount ranging from about 0.05% to 10% by weight, based on the weight of the liquid caustic. When added directly to caustic soda, it is preferred to employ from about 0.1% to 5% by weight of additive, based on the weight of the caustic.

In addition to the hereinbefore mentioned properties of the present additives, i.e., synergism in regard to low foam propagation and copper corrosion inhibition, they exhibit another. distinct property in typical brewer-adapted use solutions in that the resulting use solutions work efiicaciously over a wide temperatureg radient. The import of this is readily ackowledged by virtue of the fact that heretofore it was necessary to have separate cleaning systems for the cellar, the brewhouse, and the bottle washing station, due to the different temperatures thereat. The present use solution can be used in all three areas.

For a more complete understanding of the present invention, reference is made to the following examples, which are not to be construed as unduly limiting the invention. In the examples all parts and percentages are by weight, absent indications to the contrary.

EXAMPLE I An additive was prepared in accordance with the present invention by mixing together at about 75 F., the following:

1 Triton 11-66.

a.,a',a.-amino trls-(methyl phosphonic acid).

3 Sodium glucoheptouate.

An ethoxylated adduct of the condensation product or ethylenediamine and propylene oxide having an average molecular weight of from about 2750 to about 3350 and containing about 10% by weight of ethylene oxide.

5 A modified ethoxylated and propoxylated adduct of a fatty alcohol having a molecular weight of about 770, the ethylene oxide and propylene oxide being present in a weight ratio of about 4: 1 and sold commercially by Rohm and Haas under the name Triton DF-12.

EXAMPLE n This example illustrates various additive compositions prepared in accordance with the present invention. These compositions were prepared as described in Example I.

ADDITIVE A Ingredient: Amount, in part Water 87.5 Hydrotrope -2. 1.0 sequestering agent 1 0.5 sequestering agent 2 10.0 Nonionic surfactant A 0.5 Nonionic surfactant C 1 0.5

ADDITIVE B Ingredient: Amount, in parts Water 45.5 Hydrotrope 3.0 sequestering agent 1 2.5 sequestering agent 2 40.0 Nonionic surfactant A 4.5 Nonionic surfactant B 4.5

ADDITIVE C Ingredient: Amount, in parts Water 54.0 Hydrotrope 7.5 sequestering agent 1 1.5 Sequestering agent 2 30.0 Nonionic surfactant A 3.5 Nonionic surfactant B 3.5

1 A polyoxyethylene-polyoxypropylene block copolymer having an average molecular weight of about 2000 and containing about by weight of ethylene oxide.

EXAMPLE III This example illustrates the low foam properties of the additives of the present invention.

From each of the compositions of Examples I and II, a typical aqueous use solution was prepared. Specifically, four 2% by Weight caustic soda solutions had added thereto, respectively, 0.125% by weight of the additive of Example I, 0.5% by weight of additive A, 0.05% by weight of additive B, and 0.25% by Weight of additive C.

Each of the typical use solutions were tested for foam propagation by an aeration foam test. The test essentially comprises filling a one liter graduate cylinder with 300 mls. of test solution. A gas dispersion tube equipped with a fritted glass disc of coarse porosity is then disposed in the graduate such that the base of the tube rests on the bottom of the graduate. Air is then introduced into the graduate through the dispersion tube at a rate of 400 cc. per minute, as determined by a fiowmeter.

With air flowing through the graduate to obtain a reference level, protein soil, in this instance, homogenized whole egg is added to the solution in 10 drop increments using a pipette-type medicine dropper. After five minutes of flowing air through the solution, the volume of foam above the solution is then measured and recorded.

The test is concluded after this procedure has been repeated to the point where either 90 drops of whole egg has been added or when the foam volume exceeds 700 mls.

It has been found that when the foam level is less than 100 mls. in the presence of 60 drops of whole egg (1% egg soil on a volume bases), then a satisfactory low foaming composition is provided.

6 The results of the tests run on the additives of the present invention are set forth below in Table I.

It is seen from the data that over varying concentrations that the additives of the present invention are ef fective foam inhibitors.

EXAMPLE IV This example illustrates the low foam synergistic properties of the present invention.

A series of comparative additives were prepared from the ingredients as set forth in Table II, below. From each of these additives was prepared a typical use solution containing 2% by weight of caustic soda and 0.125 by Weight of additives.

A typical use solution was then prepared as above, but employing 0.125% by Weight of the additives of Example I. Each of the compositions were then tested for foam propagation by the aeration foam'test described in Example III. The results of these tests are set forth in Table III, below.

It can be seen by comparing the'data of the product of Example I with that from the compositions not employing all the ingredients, synergistic foam properties are obtained with the composition of the present invention.

TABLE IL-COMPARATIVE COMPOSITIONS Composition 1 2 3 4 Ingredient:

Water 44. 0 44. 0 49. 0 3B. 0 Hydrotrope- 9.0 9. 0 9. 0 9. 0 sequestering agent:

1 2.0 2. 0 2. 0 2 40. 0 40. 0 40. 0 50. 0 NOIIIgJIQIC surfactant:

1 An ethylene oxide adduct 01 the propylene oxide condensate with ethylenediamine having an average molecular weight oi about 7,500 and containing about 10% by Weight of ethylene oxide.

TABLE III.-FOAM PROPAGATION DATA Foam height, mls. oi-

- Example I Foam height, Mls.

Composition 1 2 3 4 No. drops egg soil:

EXAMPLE V weight of nonionic surfactant B, previously identified, beer copper pick-up tests were run. These tests were repeated using various other compositions typically employed as cleaning compositions for brew kettles, as well as those of the present invention. These compositions were as follows:

(E) A 2% caustic soda solution to which was added 0.25% of the additive of Example I,

(F) A 2% caustic soda solution containing 0.5% of the product of Example I,

(G) A 3% caustic soda solution containing about 450 parts by weight of sodium glucoheptonate, (H) A 3% caustic soda solution containing 5 p.p.m. of

a,a,a"-amino tris-(methyl phosphonic acid).

The test procedure employed was as follows: Copper plates measuring 3.0" x 0.8 x 0.04, were initially cleansed and then immersed in 110 mls. of the test solution in sealed four ounce bottles, for both one hour and five hours at both room temperature and 160 F.

After immersion the copper plates were expunged of any residual alkaline solution by dipping them in 1:1 hydrochloric acid solution, rinsed with copper-free distilled water and then immersed in a commercial beer, having an average copper content of 0.17 p.p.m. for two hours at room temperature.

After the two hour period, aliquot portions of the beer samples were tested for copper content thereby determining the amount of copper in the plates that had been oxidized and/or dissolved. Copper content of the beer was determined by spectrophotometn'c analysis in accordance with the Cuprethol Procedure as described by Brenner et al., American Society of Brewing Chemists Proceedings (1965), at pp. 187 to 193.

The results of these tests are set forth in the following table:

Copper pickup, p.p.m

Room temperature, 160 F., hours hours The data in the table clearly evidences the superior copper corrosion inhibition properties of the products of the present invention since neither of the sequestering agents alone approximate the properties of the combination thereof over the varying temperature parameters.

What is claimed is:

1. A liquid additive composition consisting essentially of:

(a) a hydrotrope which is an alkylphenol polyglycol ether phosphate in potassium salt form having a viscosity of 120 centipoises at 25 C., a specific gravity of 1.26, a pH of 8-10 in 5% aqueous solution and a freezing point of 20 C.;

(b) a mixture of sequestering agents, said mixture consisting of (l) u,ot',ot"-arnino tris-(methyl phosphonic acid) or the potassium or sodium salts thereof, and (2) an alkali metal salt of a sugar acid, or mixtures thereof, the sequestering agents being present in a wherein y is an integer sufficiently large to insure that the ethylene oxide constitutes a maximum of about 10% by weight of the total molecular weight of the molecule, the molecular weight of the molecule ranging from about 900 to 7800 and (2) an ethoxylated linear alcohol having from about 10 to 20 carbon atoms, the ethylene oxide being from about 20 to by weight of the total molecular weight of the molecule, a polyoxyethylene-polyoxypropylene block copolymer corresponding to the formula:

having a molecular weight of from about 900 to 4500 and wherein a;+c are sufficiently large such that the ethylene oxide being from about 0 to 10% of the total molecular weight of the compound or mixtures thereof, the nonionic surfactant mixture being present in a weight ratio of nonionic (1) to nonionic (2) of from about 1:2 to 2:1 and ((1) water.

2. The composition of claim 1 wherein said composition comprises, by weight:

(a) from about 1 to 9 percent of said hydrotrope,

(b) from about 7 to 48 percent of said mixture of sequestering agents,

(c) from about 1 to 10 percent of said mixture of now ionic surfactants, and

(d) from about 33 to 91 percent of water.

3. The composition of claim 1 wherein the alkali metal salt of the sugar acid is selected from the group consisting of sodium gluconate,,sodium glucoheptonate and mixtures thereof.

4. A use solution for cleaning-in-place system consisting of:

(a) 130m about 5,000 to 50,000 p.p.m. of liquid caustic so a,

(b) from about 500 to 100,000 p.p.m. of the additive of claim 1, and

(c) the balance being water.

5. A liquid caustic soda solution containing from about 0.05 to 10% by weight of the additive of claim 1.

References Cited UNITED STATES PATENTS 3,278,446 10/ 1966 Irani 252--545 2,992,187 7/1961 Gershon 252-156 3,235,627 2/1966 Mansfield 252-89 X 2,674,619 4/1954 Lundsted 252- X 2,979,528 4/ 1961 Lundsted 2521 10 X MAYER WEINBLA'IT, Primary Examiner U.S. Cl. X.R;