CA1082676A

CA1082676A - Preparation of neutral to slightly overbased calcium synthetic sulfonate compositions

Info

Publication number: CA1082676A
Application number: CA271,238A
Authority: CA
Inventors: Mack W. Hunt; Charles L. Pitzer
Original assignee: Witco Chemical Corp
Current assignee: Witco Corp
Priority date: 1976-04-27
Filing date: 1977-02-07
Publication date: 1980-07-29
Also published as: IT1075801B; DE2702983A1; BE853967A; GB1575957A; FR2349573A1; JPS52130804A

Abstract

PREPARATION OF NEUTRAL TO SLIGHTLY OVERBASED
CALCIUM SYNTHETIC SULFONATE COMPOSITIONS
Abstract of the Disclosure Preparation of novel neutral to slightly overbased calcium synthetic sulfonate compositions by a novel process wherein said compositions are fluid and filterable.

Description

The present invention relates to the preparation of neutral to slightly overbased calcium synthetic sulfonate compositions. Such compositions are useful as additives for diesel lubricating oils where they function to inhibit corrosion when used as fuels or lubricants and serve to maintain engine cleanliness in internal combustion engines. The overbased compositions of the present invention have base numbers in the range from 0 to about 20 (calculated in terms of mg. KOH/g.
when titrated in 50~ alcohol using phenolphthalein as the in-dicator), most advantageous being those having base numbers in the range of from about 8 to about 10.
Broadly speaking, calcium sulfonate compositions which are neutral or have low base numbers have heretofore long been known to the art, illustrative of which is U.S. Patent No. 2,402,325. Their properties from an overall standpoint leave much to be desired and methods for the preparation there-of are, not infrequently, somewhat cumbersome. Moreover, here-tofore known methods for the production of such compositions have been found not to be satisfactory when certain types of sulfonic acids are sought to be utilized in producing said compositions. Thus, in the case of synthetic sulfonic acids of the character described below, the use of which is involved in the present invention, if they are sought to be directly neutralized with basic calcium salts or compounds, such as lime or calcium hydroxide, undesired gelatinous products are formed which are solid at room temperature and are unsatis-. . .. . . . - . : . . .... . ~,: .. ......... .. ~ . : : : ., .. : . . .: . .,:;: .. ,:: . . ,. .: .

~Q~Z676 factory for the uses for which the compositions of the present invention are otherwise well adapted. If the aforesaid syn-thetic sulfonic acids are first converted into sodium salts and then sought to be metathesized to the calcium salts of said sulfonic acids, satisfactory products are not obtained, emulsification and difficult phase separation problems are en-countered and, for all practical purposes, such a procedure is commercially inoperative.
The present invention is based on the discovery that if, in the carrying out of the neutralization of the sulfonic acids of the type here involved with a basic calcium salt or ~
compound, especially calcium hydroxide, there is present a "
chloride ion in appropriate amounts, the process proceeds well and enables the preparation of a fluid, filterable, neutral or slightly overbased, as may be desired, sulfonate composition ~
which is excellently adapted for use as an additive for lubri- ~ `
cating oils, particularly diesel lubricating oils. It has been found, surprisingly, that very small proportions or amounts of chloride ion have a striking or dramatic effect on the viscosity of the finished neutral to slightly overbased calcium synthetic sulfonate compositions. The process of the present invention does not require, in the carrying out thereof, the use of hydrocarbon solvents or polar organic solvents as, for instance, heptane, hexane or octane, isopropanol, glycols, etc. The process utilizes water which renders it quite economical. The exact filterability characteristics and base number values of ;
the compositions obtained are dependent upon and can be con-trolled to a relatively small extent by the proportions of water utilized and the contact time of the reactants or the reaction mixtùre with water. Generally speaking, increasing e proportions of water used somewhat decreases the viscosity, and the situation is similar with respect to increasing the -;`

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reaction or digestion time. Increasing the proportion of chloride ion or, in other words, increasing the proportion of, say, calcium chloride, decreases the viscosity, subject to what is set forth hereafter.
The particular types of synthetic sulfonic acids which are used in the practice of the present invention are oil-soluble, have a molecular weight in the range of about 480 and 540, especially about 510 to about 525, and are in the form mainly of dialkylbenzene sulfonic acids, particularly p-dialky-lbenzene sulfonic acids in which the alkyl radicals contain predominately from 12 to 16 carbon atoms. The alkyl radicals may be branch chained or straight chain, or mixtures of branched chain and straight chain, but especially preferred are those dialkylbenzene sulfonic acids in which the alkyl radicals are highly branched chain. They are, per se, well known to the art and they are among those disclosed, ``

~2676 -4 1 for instance, in such U.S. Patents as Nos. 3,476,800 and 3,661,622.
They are, generally speaking, commonly known as Synthogen~s. A
particularly suitable commercially available oil-soluble sulfonic acid, for use in the production of the compositions of the present invention, is the product identified as "Exxon AS-ll9" ttrade mark) which contains about 89 wt.% sulfonic acids, about 0.2`wt.
free sulfuric acid, and is very low in water content, being, indee~, substantially free from water, and having a molecular weight of about 510-515 calculated as the acid. Generally speaking, the aforesaid types of synthetic sulfonic acids which are paxticularly useful in the practice of the present invention ~hould have a content of at least about 85 wt.% sulfonic acids, be~r still 88-92 wt.~; less than about 0.6 wt.% free sulfuric acid, better still 0.1 to 0.3 wt.%; and less than about 1.5 wt.%
water, better still essentially zero to 0.2 wt.~.

The source of the chloride ion is especially calcium chloride.
While other chloride salts can be used as, for instance, barium chloride or magnesium chloride, or sodium chloride or potassium chloride, certain of such chlorides tend to cause haziness in the ~inished compositions or other undesirable effects and, therefore, their use is not preferable despite the fact that the addition o the chloride ion through their use serves to achieve various of ~he objectives o the present invention. The amount of chloride salt addsd in the carrying out of t~e proce.~ shoul- he such that . ~:

:
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-- lV82676 the finished neutral or slightly overbased composition contains from about 0.1 to about 0.5 wt.~ chlorine. More than about 0.5 wt.~ is usually not needed and, preferably, the proportions of chlorine content are in the range of 0.2 to 0.4 wt.~.
In carrying out the process of the present invention, a nonvolatile diluent inert oleaginous material, particularly a pale, substantially neutral mineral or petroleum oil, is admixed, in a reactor vessel, with the synthetic sulfonic acids.
The relative proportions of the diluent and the synthetic sulfonic acid are variable and in no way critical but, usually, the diluent will be employed in amounts, by volume, several times, usually from about 5 to 10 ~imes, that of the synthetic sulonic acids. After a suitable period o mixing, lime or calcium hydroxide is added, particularly calcium hydroxide, `
under conditions of mixing, the amount of the lime or calcium hydroxide being sufficient to produce a neutral to slightly overbased composition in the final composition. Where lime is used, an adjustment as to the amount of water to be used is made in a ormulation wherein the source of calcium would be calcium hydroxide. In any event, water is then added to-gether with an aqueous solution of the chloride ion source, notably calcium chloride, and mixing is continued, and the temperature o the reaction mixture is raised, generally to about 160-180F, preferably to about 170F. This is conven-~5 iently done, or instance, by circulating the reaction mixturethrough an external heat exchanger and then back into the reactor vessel. Then an additional amount of the synthetic sulfonic acids is added at a controlled rate, to avoid exceed- ~ -ing a temperature of about 200F, said amount of the sulfonic acids taking into account the amount initial~y used and the amount of lime or calcium hydroxide previously added, and mixing is carried out generally over a period of several hours.

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6~6 To raise the temperature of the reaction mixture to ~he desired extent which, generally, should not exceed about 200F, the reaction mixture is conveniently continuously circulated through the external heat interchanger and back into the reactor. Mixing is continued generally for a period of about 1 or 2 hours or more. Upon completion of the reaction, the reaction mixture is desirably dehydrated to produce a final composition substantially free of water. This can be accom-plished by procedures well known to the art but is generally most conveniently done by heating the reaction mixture to a temperature in the range of about 250-350F and stripping by blowing with air or with an inert gas such as nitrogen. It will be understood that the order of mixing of the reactants is vaxiable and various mixing and other equipment can readily be selected as will be apparent to those versed in the art.
While, as indicated above, it is particularly desir-able that the diluent be a pale, substantially neutral mineral or petroleum oil, other nonvolatile liquid diluents which can be used include synthetic lubricating oils; animal oils such as lard oil and sperm oil; and vegetable oils such as cotton-seed oil and corn oil.
The following examples are illustrative of the practice of the present invention but are in no way limitatlve thereof since variations can readily be made in light of the guiding principles and teachings disclosed above.
Examples 1-4 A 3-liter flask equipped with thermometer, straight ; glass tube in the center neck, condenser and connection of~
said glass tube to a source of air for agitating the reaction mixture is charged with 531g of a pale, neutral mineral oil, and air is passed into the oil at the rate of about 1 liter/

minute via a Kontes air flowrater #2PA. The air flow is ~82676 continued throughout the procedure described below. The oil is heated slowly to about 1400F. Then 66g (10 wt.%) of Exxon AS-ll9 sulfonic acid, previously heated to about 1800F, is added to the oil to facilitate good mixing of the Ca(OH)2 and water which is next introduced into the flask, 54g of calcium hydroxide being gradually added along with variable amounts of water as indicated below. The reaction mixture is then heated to about 180F and then an additional 593g of the Exxon AS-ll9, previously heated to about 180F, is added slowly over a period of about 30 minutes. The temperature of the reaction mixture is adjus~ed to about 2000F and maintained for about 1-1/2-3 hours as set out below. The water is then removed from said reaction mixture by heating to about 325F, followed by air stripping at said temperature. In these first four examples, the only variables are the quantities of water used and the digestion times involved. The results are shown be]ow:
Example 1 Example 2 Example 3 Example 4 Water 150 90 150 90 Digestion time, 90 90 180 180 minutes % Sediment 3.0 3.0 2.2 2.4 Filtration time, seconds 4~ Kenite 700 130 130 105 113 2% Kenite 700 - - 123 123 Filtrate ~ Sediment 0.03 0.03 0.03 0.01 ~`
Base Number 10.8 10.5 12.8 12.4 ~ Active 46 46 46 46 Appearance BrightBright Bright Bright The compositior~s resulting from Examples 1-4 are ~ ~-excellent.
Example 5 171 gallons of a synthetic sulfonic acid (Exxon AS-119) and 1472 gallons of a pale, substantially neutral petro-leum diluting oil are charged to a reactor fitted with an air -~z~
inlet for effectting agitation or mixing of the ingredients.
The air is turned on and mixing is effected thereby for a period of about 15 minutes. Then 1100 pounds of calcium hydroxide are added and air mixing is carried out for about 15 minutes. Then 280 gallons of water and 30 gallons of a 46~
water solution of calcium chloride are added. The contents of the reactor are circulated through an external heat exchanger, and then back into the reactor, to raise the temperature of said reactor contents to about 170F. Then 1549 gallons of the aforesaid synthetic sulfonic acid are gradually added over a period of several hours to the reactor while continuing the circulation through the heat exchanger. The temperature of the reaction mixture is controlled so that it does not exceed 200F and, to this end, the rate of the addition of said 1549 gallons of the sulfonic acid is controlled to avoid exceeding `
the aforesaid 200F. After all of the sulfonic acid is added the contents of the reactor are air mixed for about 15 minutes, and circulation and recirculation through the heat exchanger and the reactor is continued for a period of 2 hours with the reaction mixture being maintained at about 2000F while also being air mixed. After the completion of the reaction, the product is heated and blown with air to dehydrate it, and then filtered.
Example 6 .
171 gallons of a synthetic sulfonic acid (Exxon AS-119) and 1410 gallons of a pale, substantially neutral petro-leum diluting oil are charged to a reactor fitted with an air inlet for effecting agitation or mixing of the ingredients.
The air is turned on and mixing is effected thereby for a period of about 15 minutes. Then 1000 pounds of calcium hydroxide are added and air mixing is carried out for about 15 minutes. Then 260 gallons of water and 30 gallons of a 46%

iL~8Z676 water solution of calcium chloride are added. The contents of the reactor are circulated through an external heat exchanger, and then back into the reactor, to raise the temperature of said reactor contents to about 1700F. Then 1484 gallons of the aforesaid synthetic sulfonic acid are gradually added over a period of several hours to the reactor while continuing the circulation through the heat exchanger. The temperature of the reaction mixture is controlled so that it does not exceed 200F and, to this end, the rate of the addition of said 1484 gallons of the sulfonic acid is controlled to avoid exceeding the aforesaid 200F. After all of the sulfonic acid is added `~
the contents of the reactor are air mixed for about 15 minutes, and circulation and recirculation through the heat exchanger and the reactor is continued for a period of 2 hours with the lS reaction mixture being maintained at about 200F while also being air mixed. After the completion of the reaction, the ~ "
product is heated and blown with air to dehydrate it, and then filtered.
Examples 7-9 The following Examples are carried out in the manner disclosed in Example 5, using the following ingredients in the stated amounts and resulting in the indicated compositions or products. ~ `

~08;~676 Ingredients (pounds) Example 7 Example 8 Example 9 Exxon Sulfonic Acid 13,311 13,311 12,823 Diluting Oil 9,974 9,974 9,554 Ca(OH)2 1,100 1,100 1,000 Water 2,342 2,342 2,169 CaC12 Solution (46%) 370 370 370 Filter Aid 350 500 600 Product % Calcium Sulfonate 50.8 50.8 51.5 % Oil (calculated) 47.7 47.8 47.1 :
Base Number 15.3 14.9 15.8 Lbs./Gal. 7.76 7.76 7.76 Viscosity, SUS at 210F 275 251 210 Sediment 0.016 0.010 .004 : 15 % Water 0.4 0.4 0.4 % Chlorine 0.3 0.3 0.3 The compositions of Examples 7, 8 and 9 can readily be diluted to a lower use concentration of active material, as by dilu-ting with mineral oils such as the diluting oil, illustratively by adding 5,142 pounds of such diluting oil to each of said compositions whereby to produce compositions falling within the analysis range of the (A) compositions as set forth below.
Typical filtered compositions made in accordance with the present invention correspond to the following approxi-mate analyses, the percentages being given by weight: .
(A) % Calcium sulfonate 45-48 % Chlorine 0.2-0.5 Base Number 5-14 Viscosity, SUS at 210F 150~250 ~2~;'7~;
(B) % Calcium sulfonate 50.3 ~ Chlorine 0.3 Base Number 15.3 Viscosity SUS at 210F 275 Generally speaking, concentrate compositions produced accord-ing to the present invention desirably contain from about 40 to 50 wt.~ of the calcium salt of the synthetic oil-soluble sulfonic acids.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process of preparing fluid, filterable neutral to slightly overbased calcium synthetic sulfonate compositions in which said overbased compositions have base numbers from zero up to about 20, which comprises initially admixing (a) oil-soluble synthetic sulfonic acids having a molecular weight in the range of about 480 and 540 and being in the form of alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids and in which the alkyl radicals contain predominately from 12 to 16 carbon atoms, the amount of said (a) ingredient being substan-tially less than the total thereof to be utilized, with (b) several times the volume of said (a) ingredient of a mineral diluting oil, then admixing therewith (c) calcium hydroxide, (d) water and (e) calcium chloride and reacting said admixture at an elevated temperature but not exceeding about 200°F, then gradually adding an additional amount of the (a) ingredient sub-stantially in excess of that initially used at a rate and under conditions whereby the temperature of the resulting mixture does not exceed about 200°F, the total amount of the (a) ingredient and the (c) ingredient being such as to provide in the overbased compositions a base number in the range of zero up to about 20 and a content from about 40 to 50 weight% of calcium salt of said sulfonic acids in the compositions, the amount of said (e) ingre-dient being such that the finished compositions contain from about 0.1 to about 0.5 weight% chlorine, and continuing the reaction, under conditions of agitation at a temperature not exceeding about 200°F, and then removing substantially all of the water from the reacted mixture.

2. The process of claim 1, in which the oil-soluble sulfonic acids are in the form of a composition containing at least about 85 weight% sulfonic acids, less than about 0.6 weight% sulfuric acid, and less than about 1.5 weight% water.

3. The process of claim 2, in which the oil-soluble sulfonic acids are in the form of a composition containing from 88-92 wt.% sulfonic acids, from 0.1 to 0.3 wt.% sulfuric acid, and 0 to 0.2% water.

4. The process of claim 1, in which the alkyl groups of the alkylbenzenes are highly branch chains, the said sulfonic acids having a molecular weight in the range of about 510-515, and in which the overbased compositions prepared have a base number in the range of about 6 to 14.