US3748353A

US3748353A - Method of improving detergency of alkylphenol polysulfonates by base precipitation and separation

Info

Publication number: US3748353A
Application number: US00124424A
Authority: US
Inventors: E Hannah
Original assignee: Chevron Research and Technology Co
Current assignee: Chevron USA Inc
Priority date: 1971-03-16
Filing date: 1971-03-16
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24

Abstract

PROCESS FOR ENHANCING THE DETERGENCY OF LINEAR ALKYLPHENOL POLYSULFONATE DETERGENT ACTIVES CONTAINING FROM 25 TO 50 MOL PERCENT OF PARA-ALKYL MATERIALS WHICH COMPRISES MIXING SUFFICIENT BASE WITH THE MATERIAL IN AQUEOUS SOLUTION TO FORM A PRECIPITATE AND REMOVING THE PRECEIPITATE.

Description

United States Patent METHOD OF HVIPROVING DETERGENCY 0F ALKYLPHENOL POLYSULFONATES BY BASE PRECIPITATION AND SEPARATION Eric D. Hannah, Mill Valley, Califl, assignor to Chevron Research Company, San Francisco, Calif. No Drawing. Filed Mar. 16, 1971, Ser. No. 124,424 Int. Cl. Clld 1/22 US. Cl. 260-512 R 6 Claims ABSTRACT OF THE DISCLOSURE Process for enhancing the detergency of linear alkylphenol polysulfonate detergent actives containing from to 50 mol percent of para-alkyl materials which comprises mixing suflicient base with the material in aqueous solution to form a precipitate and removing the precipitate.

BACKGROUND OF THE INVENTION This invention is concerned with a process for producing heavy duty detergents which perform effectively in the absence of phosphate builders.

The concern over increasing growth of algae in the nations streams and lakes has caused a search to be made for detergents which will perform without the use of additional phosphate building compounds such as sodium polyphosphate. These materials are believed to be a cause of the algae growth and consequent eutrophication.

In US. patent application Ser. No. 34,886, filed May 5, 1970, there are disclosed and claimed polysulfonated alkylphenols which perform the desired heavy duty phosphate-free washing quite effectively. These compounds are of the formula:

in which R is linear alkyl of 16 to 22 carbon atoms, X is H or a water-soluble salt-forming cation, n is at least 1.5, and not more than 25 mol percent of the sulfonated alkylphenols have R attached on the aromatic nucleus in a position para to OX.

These materials are produced by the sulfonation of appropriate alkylphenols followed by neutralization with a suitable salt-forming cation. Thus the salt-forming cation X may be alkali metal, alkaline earth metal, ammonium, or various organic cations. The alkylphenols used must have a low para-alkyl content (less than 25 mol percent) and thus are usually prepared by specific alkylation processes which produce high ortho content compounds. Included among the ortho alkylation techniques are thermal alkylation and the utilization of various catalysts such as aluminum, magnesium, hydrogen fluorine-treated aluminum silicate, alkyl sulfonic acids, etc.

Phenol alkylation using conventional acidic catalysis such as the Friedel-Crafts catalysts, including aluminum chloride, zinc chloride, ferric chloride, etc., produces alkylphenols in which the para isomer content is generally from to 50%. Upon sulfonation these materials do not form satisfactory detergents. It is therefore desirable to provide a method for improving the products derived from the conventionally produced alkylphenol mixtures into useful, effective detergents.

SUMMARY OF THE INVENTION A process is provided for converting linear alkylphenol polysulfonate mixtures having a high proportion of para alkyl content into mixtures having improved detergency,

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the mixtures produced being suitable for use as heavy duty detergent actives. This is accomplished by mixing base with an aqueous solution of alkylphenol polysulfonates of the formula in which R is linear alkyl of 16 to 22 carbon atoms, from about 25 to about 50 mol percent of which is attached in a position para to OX, X is H or a Water-soluble saltforming cation, and n is at least 1.5, the base being added in sufficient quantity to form a precipitate, and separating the precipitate which forms. The separation of the precipitate may be accomplished by filtration, centrifugation, or other conventional techniques for separating solid and liquid phases.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The aqueous solution of polysulfonate should have a concentration of between about 1 and 50 weight percent, preferably between about 5 and 25 weight percent.

Bases which can be added to raise the pH of the solution to the proper range include the oxides and hydroxides of alkali metals and alkaline earth metals as well as various organic base materials. The preferred materials are the alkali metal hydroxides and oxides. The preferred material is sodium hydroxide. The bases may be added directly to the solution or may themselves be in aqueous solution when added.

As previously noted, the precipitate which forms upon base addition can be removed by any suitable technique, e.g. settling and decantation, filtration or centrifugation. However, it is preferred that the precipitated material be removed by centrifugation, as, due to the gelatinous nature of some of the precipitates, filtration is rather difficult to perform.

The alkylphenols which are employed to produce the polysulfonates which in turn are employed in the processes of this invention are those derived by the alkylation of phenol with olefins, halides, or alcohols using conventional acid catalysis. The catalysts which are employed are typically the Friedel-Crafts type catalysts including aluminum chloride, zinc chloride, ferric chloride, etc., and other acidic catalysts such as activated clay and hydrogen fluoride. The alkylphenols produced by alkylation with these materials typically have para alkyl contents of between about 35 and 50% The sulfonation of the alkylphenols to produce the feed compounds of this invention may be accomplished by any suitable method. Thus, sulfonating agents which may be reacted with the alkylphenol include chlorosulfonic acid, oleum, or sulfuric acid. It is only important that enough sulfonating agent be employed to incorporate an average of at least 1.5, preferably 1.6 atoms of sulfur (in the form of sulfonate groups) into each molecule. That is, over one-half of the molecules are disulfonated. Each sulfonate group incorporated into these alkylphenols can be measured as a surface active site by titration. This number is referred to as active group incorporation (AGI). Sulfonation with oleum is preferred.

The sulfonation is usually accomplished with a ratio of at least 2 and preferably from 4 to 10 mols of available S0 from the sulfonating agent to one mol of the alkylphenol. The use of a solvent is ordinarily not required in carrying out the sulfonation. The alkylphenol and the sulfonating agent are simply mixed and the reaction is allowed to proceed. maintaining the temperature of the reaction mixture within the desired limits. The time required for disulfonation will be dependent upon the reaction temperature, the sulfonating agent, the ratio of sulfonating agent to alkylphenol, and the total quantity of reactants present. The reaction is usually etfected at a temperature in the range of to 150 0., preferably 25 to 100 C.

The processes of the invention are described in the following examples:

EXAMPLE 1 Precipitation of alkylphenol polysulfonates by a base TABLE I Alkylphenol disulfonate Percent ofpH at .Alkyl chain initial length o-Alkyl p-Alkyl clouding ca. 65 ca. 35 9. 6

62 38 9. 5 ca. 65 ea. 35 9. 4 67 33 9. 6 95 5 It was noted that each of the materials in which the phenol contained over 25% of the p-alkyl isomer formed a precipitate while the materials having less than this amount of p-alkyl isomer did not form a precipitate even at a pH of 13.5.

EXAMPLE 2 Isolation of a high detergency alkylphenol polysulfonate by base addition The feed stock for this experiment was an aqueous solution containing 6.7% by weight of alkylphenol polysulfonate in which the alkyl groups contained from 18 to 20 carbon atoms, and were attached about 62% ortho and 38% para. The sulfonates contained an average of 1.8 sulfonate groups per molecule. Four 40-ml. portions were placed in four centrifuge tubes. To each tube was added 3 ml. of 2.5 N NaOH and all were centrifuged. A heavy oily brown layer of about 1 ml. volume settled to the bottom in each tube. The supernatant liquid was separated and analyzed. The concentration of the polysulfonate in the supernatant solution was found to be about 3.6% based on original volume. Therefore, 54% of the original active remained in solution and the separated precipitate contained 46% of the active. Detergency of the original composition and of both the precipitate and filtrate materials were determined by the following procedure.

Detergency of the compounds produced by the process of the present invention is measured by their ability to remove natural sebum soil from cotton cloth. By this method, small swatches of cloth, soiled by rubbing over face and neck, are washed with test solutions of detergents in a miniature laboratory washer. The quantity of soil removed by this washing procedure is determined by measuring the reflectances of the new cloth, the soiled cloth, and the washed cloth, the results being expressed as percent soil removal. Because of variations in degree and type of soiling, in water and in cloth, and other unknown variables, the absolute value of percent soil removal is not an accurate measure of detergent eifectiveness and cannot be used to compare various detergents. Therefore, the art has developed the method of using relative detergency ratings for comparing detergent effectiveness.

The relative detergency ratings are obtained by comparing and correlating the percent soil removal results from solutions containing the detergents being tested with the results from two defined standard solutions. The two standard solutions are selected to represent a detergent system exhibiting relatively high detersive characteristics and a system exhibiting relatively low detersive characteristics. The systems are assigned detergency ratings of 6.3 and 2.2 respectively.

By washing portions of each soiled cloth with the standardized solutions, as well as with two test solutions, the results can be accurately correlated. The two standard solutions are identical in formulation but are employed at different hardnesses.

STANDARD SOLUTION FORMULATION The standard exhibiting high detersive characteristics (Control B) is prepared by dissolving the above formulation (1.0 g.) in one liter of 50 p.p.m. hard water (calculated as calcium carbonate and /a magnesium carbonate). The low detersive standard (Control A) contained the formulation (1.0 g.) dissolved in one liter of p.p.m. water (same basis).

A miniature laboratory washer is so constructed that four diiferent solutions can be used to wash different parts of the same swatch. This arrangement ensures that all four solutions are working on identical soil (natural facial soil). Relative detergency ratings (RDRs) are calculated from soil removals (SRs) according to the equation:

RDR=22 +4.1

A further refinement in the determination of relative detergency ratings was developed. In this method, instead of employing two standard formulations, one of the formulations used in preparing the four test solutions had a known relative detergency rating (RDR) which had been determined by the above formula. Relative detergency ratings of the other three formulations were then determined by comparing the percent soil removal (SR) of these formulations with that of the known formulation.

Table II presents detergency data on a group of the products obtained in Example 2 including the original mixture, the precipitate, the filtrate, and for comparison the detergency rating is given for a linear alkylbenzene sulfonate (LAS) having from 11 to 14 carbon atom straight chain alkyl groups. The LAS data are given both with and without phosphate builder.

Each formulation tested comprised 25 weight percent of the test material along with 1% carboxymethylcellulose, 7% sodium silicate, 8% water, and 59% sodium sulfate. The LAS comparison formulations were prepared in the same way, except that in the phosphate-containing example only 20% of LAS was used and most of the sodium sulfate was replaced by an equal amount of sodium triphosphate, thereby producing a formulation having 40% triphosphate and 19% sulfate, both as sodium salts. The test results were obtained at a pH of 7 except for the two LAS examples, which were run at a pH of 9 (without phosphate) and 10 (with phosphate).

LAS (20%) sodium triphosphate (40%).. 5.7 3.7 Example 2:

Original mixture 4. 7 0. 2

Preclpitate 2. 8 0.

ate 5. 2. 2

It may be noted that the relative detergency of the filtrate of Example II is significantly better than that of the original material. This improvement is obtained by base precipitation and removal of the precipitate (which displayed essentially no detergency in hard Water).

While the character of this invention has been described in detail with numerous examples, this has been done by way of illustration only and without limitation of the invention. It will be apparent to those skilled in the art that modifications and variations of the illustrative examples may be made in the practice of the invention within the scope of the following claims.

What is claimed is:

1. A method for improving the heavy duty detergency of an alkylphenol polysulfonate of the formula in which R is linear alkyl of 16 to 22 carbon atoms and from about 25% to being attached in a position para to OX, X is H or a alkali metal, alkaline earth metal or ammonium cation, n is an average of at least 1.5, said method comprising the steps of mixing sufficient base With an aqueous solution containing from 1 to 50 weight percent of said polysulfonate to form a precipitate in the solution, and separating the precipitate from the solution and recovering th'e supernatant liquid.

2. The method of claim 1 in which the base employed in an alkali metal oxide or hydroxide.

3. The method of claim 2 in which the base is sodium hydroxide.

4. The method of claim 1 in which the polysulfonate is present in the aqueous solution in an amount of from about 1 to 25 weight percent.

5. The method of claim 4 in which the polysulfonate is present in the aqueous solution in an amount of from about 5 to 15 weight percent.

6. The method of claim 1 in which the precipitate is separated from the aqueous solution by centrifugation.

References Cited UNITED STATES PATENTS 2,249,757 7/ 1941 Flett 260512 2,205,946 6/1940 Flett 260--512 2,205,948 6/1940 Flett 260512 2,233,408 3/1941 Flett 260505 2,283,199 5/ 1942 Flett 260505 LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US. Cl. X.R. 25 25 5 8