GB1575957A - Process for the preparation of neutral to slightly overbased calcium synthetic sulphonate compositions - Google Patents

Description

(54) PROCESS FOR THE PREPARATION OF NEUTRAL TO SLIGHTLY OVERBASED CALCIUM SYNTHETIC SULFONATE COMPOSITIONS (71) We, WITCO CHEMICAL CORPORATION, a Corporation organised and existing under the laws of the State of Delaware, United States of America, of 277 Park Avenue, New York, State of New York, 10017, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 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 indicator), most advantageous being- those having base numbers in the range of from about 8 to about 10.

Calcium sulfonate compositions which are neutral or have low base numbers have long been known and are described, for example, in U.S. Patent No. 2,402,325. Their properties from an overall standpoint leave much to be desired and methods for their preparation are, not infrequently, somewhat cumbersome. Moreover, the known methods for the production of these compositions have been found not to be satisfactory when certain types of sulfonic acids are used 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 attempts are made to neutralize them 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 unsatisfactory for the uses for which the compositions of the present invention are otherwise well adapted. If the aforementioned synthetic sulfonic acids are first converted into sodium salts and then converted to their calcium salts, satisfactory products are not obtained, emulsification and difficult phase separation problems are encountered and, for all practical purposes, such a procedure is commercially inoperative.

We have now discovered 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, a chloride ion is present 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 lubricating oils, particularly diesel lubricating oils.

According to the present invention there is provided a process of preparing neutral or slightly overbased calcium sulfonate compositions of low viscosity containing from 40 to 50 wt.% calcium sulfonate which comprises reacting, under conditions of agitation, a mixture of (a) oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of from 480 to 540, (b) a nonvolatile liquid oleaginous diluent, (c) calcium oxide or calcium hydroxide, (d) a source of chloride ion to provide a chlorine content of from 0.1 to 0.5 wt. /,, in the composition, and (e) water, and then removing substantially all of the water from the mixture after reaction.

It has been found, surprisingly, that very small proportions or amounts of chloride ion have a marked effect on the viscosity of the neutral or slightly overbased calcium synthetic sulfonate compositions. The process of the present invention does not require the use of hydrocarbon solvents or polar organic solvents such as heptane, hexane, octane, isopropanol or glycols. The process utilizes water which makes it economical. The filterability characteristics and base number values of the compositions obtained are dependent upon and can be controlled to a relatively small extent by the proportions of water utilized and the contact time of the reactants or the reaction mixture with water. Generally speaking, increasing the proportion of water used decreases the viscosity, and the situation is similar with respect to increasing the reaction or digestion time. Increasing the proportion of chloride ion generally decreases the viscosity.

The particular types of synthetic sulfonic acids which are used in the process of the present invention are oil-soluble, have a molecular weight in the range of from 480 to 540, preferably from 510 to 525, and are in the form mainly of dialkylbenzene sulfonic acids, particularly p-dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms.

The alkyl groups may be branched chain or straight chain, or mixtures of branched chain and straight chain groups, but especially preferred are those dialkylbenzene sulfonic acids in which the alkyl groups are highly branched chains.

They are, per se, well known in the art and they are among those disclosed, for example, in U.S. Patents Nos. 3,476,800 and 3,661,622. They are, generally speaking, commonly known as Synthogenes. A particularly suitable commercially available oil-soluble sulfonic acid, for use in the process of the present invention, is "Exxon AS-119" which contains about 89 wt.O/, alkyl benzene sulfonic acids, about 0.2 wt.V0 free sulfuric acid, is substantially free from water, and has a molecular weight of about 510 to 515 calculated as the acid. Generally, the synthetic sulfonic acids which are particularly useful in the process of the present invention should have a content of at least about 85 wt.V0 sulfonic acids, preferably 88 to 92 wit.%; less than about 0.6 wt.V free sulfuric acid, preferably 0. I to 0.3 wit.%; and less than 1.5 wit.0% water, preferably zero to 0.2 wt. /a.

The amount of calcium oxide or calcium hydroxide employed in the process of the invention is generally sufficient to provide an overbased composition having a base number in the range of from 6 to 14.

The source of the chloride ion is preferably calcium chloride. While other chloride salts can be used, for example, barium chloride, magnesium chloride, sodium chloride or potassium chloride, certain of these chlorides tend to cause haziness in the products or other undesirable effects and, therefore, their use is not preferred. The amount of chloride used in the process should be such that the neutral or slightly overbased composition produced contains from 0.1 to 0.5 wt. /n chlorine. More than about 0.5 wt. /n is usually not required and, preferably, the chlorine content is in the range of from 0.2 to 0.4 wt.O/,.

In carrying out the process of the present invention, a nonvolatile diluent inert oleaginous material, preferably a pale, substantially neutral mineral or petroleum oil, is admixed, in a reaction vessel, with the synthetic sulfonic acids. The relative proportions of the diluent and the synthetic sulfonic acid are variable and in no way critical. Generally, the diluent is employed in amounts of from 5 to 10 times by volume, that of the synthetic sulfonic acids. After a period of mixing, lime or calcium hydroxide is added, preferably calcium hydroxide. The amount of the lime or calcium hydroxide used is sufficient to produce a neutral to slightly overbased final product. When lime is used, an adjustment of the amount of water used must be made to a formulation in which the source of calcium is calcium hydroxide. Water is then added together with an aqueous solution of source of the chloride ion, preferably calcium chloride, and mixing is continued.

The temperature of the reaction mixture is raised, generally to 160 to 1800 F, preferably to about 1700F. This is conveniently done, for example, by circulating the reaction mixture through an external heat exchanger and then back into the reaction vessel. An additional amount of the synthetic sulfonic acids is then added at a controlled rate, to avoid exceeding a temperature of about 200"F. The amount of the sulfonic acids added at this stage takes into account the amount initially used and the amount of lime or calcium hydroxide previously added, and mixing is carried out generally over a period of several hours. To raise the temperature of the reaction mixture to the desired extent which, generally, should not exceed about 200"F, the reaction mixture is conveniently continuously circulated through the external heat interchanger and back into the reactor. Mixing is generally continued 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 accomplished by well known procedures but is generally most conveniently effected by heating the reaction mixture to a temperature in the range of from 250 to 3500F 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 variable and various mixing and other equipment can readily be selected.

While the diluent is preferably 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 cottonseed oil and corn oil.

The present invention also provides a neutral or overbased calcium sulfonate composition having a base number in the range of from 0 to 20 which comprises a nonvolatile liquid oleaginous diluent, from 40 to 50 wit.% of the calcium salts of oilsoluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of from 480 to 540 and from 0.1 to 0.5 wt.O/, chlorine derived from a chloride salt, the percentages being based on the weight of the composition, whenever produced by the above process.

Preferably, this composition has a base number in the range of from 6 to 14.

Moreover, this composition generally is constituted by 45 to 48 wt.% of the calcium salts of the synthetic oil-soluble sulfonic acids and from 0.2 to 0.5 wt.% of chlorine, the percentages being based on the weight of the composition.

The following non-limiting Examples illustrate the present invention.

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 531 g of a pale, neutral mineral oil, and air is passed into the oil at the rate of about I liter/minute via a Kontes air flowrater #2PA. The air flow is continued throughout the procedure described below. The oil is heated slowly to about 140"F. Then 66 g (10 wt.%) of Exxon AS-l 19 sulfonic acid, previously heated to about 180"F, is added to the oil to facilitate good mixing of the Ca(OH)2 and water which is next introduced into the flask, 54 g of calcium hydroxide being gradually added along with variable amounts of water as indicated below. The reaction mixture is then heated to about 1800F. and then an additional 593 g of the Exxon AS-I 19, previously heated to about 1800F, is added slowly over a period of about 30 minutes.

The temperature of the reaction mixture is adjusted to about 200"F 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 325"F, 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 shpwn below: Example I Example 2 Example 3 Example 4 Water (grams) 150 90 150 90 Digestion time, minutes 90 90 180 180 % Sediment 3.0 3.0 2.2 2.4 Filtration time, seconds 4% Kenite 700 130 130 105 113 2 /n Kenite 700 123 123 Filtrate Vn 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 Bright Bright Bright Bright The compositions 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 petrolem 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 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 460/n 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 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 2000F and, to this end, the rate of the addition of said 1549 gallons of the sulfonic acid is controlled to avoid exceeding the aforesaid 200"F. 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 200"F 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 petroleum 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 /n 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 170"F. 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 200"F and, to this end, the rate of the addition of said 1484 gallons of the sulfonic acid is controlled to avoid exceeding the aforesaid 200"F. 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 200"F 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.

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 CaCI2 Solution (460/,) " 370 370 370 Filter Aid 350 500 600 Product /a CalciumSulfonate 50.8 50.8 51.5 /n Oil (calculated) - 47 7 47.8 47.1 Base Number 15.3 14.9 15.8 Viscosity, SUS at 2100F 275 251 210 Sediment 0.016 0.010 .004 O/, 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 diluting 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 approximate analyses, the percentages being given by weight: (A) /n Calcium sulfonate 4548 % Chlorine 0.2-0.5 Base Number 6-14 Viscosity SUS at 2100F 150--250 (B) /n Calcium sulfonate 50.3 % Chlorine 0.3 Base Number 15.3 Viscosity SUS at 2100F 275 Generally speaking, concentrate compositions produced according to the present invention desirably contain from about 40 to 50 wit.% of the calcium salt of the synthetic.oil-soluble sulfonic acids.

WHAT WE CLAIM IS: 1. A process of preparing neutral to slightly overbased calcium sulfonate compositions of low viscosity containing from 40 to 50 wit.% calcium sulfonate which comprises reacting, under conditidns of agitation, a mixture of (a) oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of from 480 to 540, (b) a nonvolatile liquid oleaginous diluent, (c) calcium oxide or calcium hydroxide, (d) a source of chloride ion to provide a chlorine content of from 0.1 to 0.5 wt% in the composition and (e) water, and then removing substantially all of the water from the mixture after reaction.

2. A process as claimed in claim 1 wherein the oil soluble sulfonic acids are in the form of a composition containing at least 85 wt.% sulfonic acids, less than 0.6 wt.% sulfuric acid, and less than 1.5 wt.% water.

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

4. A process as claimed in any one of the preceding claims wherein the source of the chloride ion is calcium chloride.

5. A process as claimed in any one of the preceding claims wherein the nonvolatile liquid oleaginous diluent is a mineral oil.

6. A process as claimed in any one of the preceding claims wherein the alkyl groups of the dialkylbenzenes are highly branched groups.

7. A process as claimed in any one of the preceding claims wherein the sulfonic acids have a molecular weight in the range of from 510 to 525.

8. A process as claimed in any one of the preceding claims wherein the amount of calcium oxide or calcium hydroxide employed is sufficient to provide an overbased composition having a base number in the range of from 6 to 14.

9. A process of preparing neutral to slightly overbased calcium sulfonate compositions containing from 40 to 50 wt.% calcium sulfonate which comprises initially admixing (a) oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl radicals contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of about 480 to 540, the amount of ingredient (a) being substantially less than the total thereof to be utilized, with (b) several times the volume of ingredient (a) of a petroleum diluting oil, then admixing therewith (c) calcium hydroxide, (d) water and (e) calcium chloride to provide a chlorine content of 0.1 to 0.5 wt.% in the composition and reacting said admixture at an elevated temperature below 2000F., then gradually adding an additional amount of ingredient (a) substantially in excess of that initially used, the total amount of ingredient (a) and ingredient (c) being such as to provide a base number in the range of from 0 to 20 in the overbased compositions, the amount of ingredient (e) being such as to substantially decrease the viscosity of the overbased compositions, and continuing the reaction, under conditions of agitation, at a temperature below 2000F, and then removing substantially all of the water from the mixture after reaction.

10. A process as claimed in Claim 1 substantially as hereinbefore described with reference to any one of the Examples.

11. A neutral or slightly overbased calcium sulfonate composition whenever prepared by a process as claimed in any one of claims 1 to -i I.

12. A neutral or overbased calcium sulfonate composition having a base number in the range of from 0 to 20 which comprises a nonvolatile liquid oleaginous diluent, from 40 to 50 wt.%, of the calcium salts of oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of from 480 to 540 and from 0. to 0.5 wt.% chlorine derived from a chloride salt, the percentages being based on the weight of the composition, whenever prepared by a process as claimed in any one of claims 1 to 10.

13. A composition as claimed in claim 12 wherein the base number of the composition is in the range from 6 to 14.

14. A composition as claimed in claim 12 or claim 13 wherein the diluent is a mineral oil.

15. A composition as claimed in any one of claims 12 to 14 wherein the chlorine is present as calcium chloride.

16. A composition as claimed in any one of claims 12 to 15 wherein the calcium salt of the synthetic oil-soluble sulfonic acids

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (16)

**WARNING** start of CLMS field may overlap end of DESC **. compositions produced according to the present invention desirably contain from about 40 to 50 wit.% of the calcium salt of the synthetic.oil-soluble sulfonic acids. WHAT WE CLAIM IS:

1. A process of preparing neutral to slightly overbased calcium sulfonate compositions of low viscosity containing from 40 to 50 wit.% calcium sulfonate which comprises reacting, under conditidns of agitation, a mixture of (a) oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of from 480 to 540, (b) a nonvolatile liquid oleaginous diluent, (c) calcium oxide or calcium hydroxide, (d) a source of chloride ion to provide a chlorine content of from 0.1 to 0.5 wt% in the composition and (e) water, and then removing substantially all of the water from the mixture after reaction.

2. A process as claimed in claim 1 wherein the oil soluble sulfonic acids are in the form of a composition containing at least 85 wt.% sulfonic acids, less than 0.6 wt.% sulfuric acid, and less than 1.5 wt.% water.

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

4. A process as claimed in any one of the preceding claims wherein the source of the chloride ion is calcium chloride.

5. A process as claimed in any one of the preceding claims wherein the nonvolatile liquid oleaginous diluent is a mineral oil.

6. A process as claimed in any one of the preceding claims wherein the alkyl groups of the dialkylbenzenes are highly branched groups.

7. A process as claimed in any one of the preceding claims wherein the sulfonic acids have a molecular weight in the range of from 510 to 525.

8. A process as claimed in any one of the preceding claims wherein the amount of calcium oxide or calcium hydroxide employed is sufficient to provide an overbased composition having a base number in the range of from 6 to 14.

9. A process of preparing neutral to slightly overbased calcium sulfonate compositions containing from 40 to 50 wt.% calcium sulfonate which comprises initially admixing (a) oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl radicals contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of about 480 to 540, the amount of ingredient (a) being substantially less than the total thereof to be utilized, with (b) several times the volume of ingredient (a) of a petroleum diluting oil, then admixing therewith (c) calcium hydroxide, (d) water and (e) calcium chloride to provide a chlorine content of 0.1 to 0.5 wt.% in the composition and reacting said admixture at an elevated temperature below 2000F., then gradually adding an additional amount of ingredient (a) substantially in excess of that initially used, the total amount of ingredient (a) and ingredient (c) being such as to provide a base number in the range of from 0 to 20 in the overbased compositions, the amount of ingredient (e) being such as to substantially decrease the viscosity of the overbased compositions, and continuing the reaction, under conditions of agitation, at a temperature below 2000F, and then removing substantially all of the water from the mixture after reaction.

10. A process as claimed in Claim 1 substantially as hereinbefore described with reference to any one of the Examples.

11. A neutral or slightly overbased calcium sulfonate composition whenever prepared by a process as claimed in any one of claims 1 to -i I.

12. A neutral or overbased calcium sulfonate composition having a base number in the range of from 0 to 20 which comprises a nonvolatile liquid oleaginous diluent, from 40 to 50 wt.%, of the calcium salts of oil-soluble alkylbenzene sulfonic acids containing mainly dialkylbenzene sulfonic acids in which the alkyl groups contain predominantly from 12 to 16 carbon atoms and having a molecular weight in the range of from 480 to 540 and from 0. to 0.5 wt.% chlorine derived from a chloride salt, the percentages being based on the weight of the composition, whenever prepared by a process as claimed in any one of claims 1 to 10.

13. A composition as claimed in claim 12 wherein the base number of the composition is in the range from 6 to 14.

14. A composition as claimed in claim 12 or claim 13 wherein the diluent is a mineral oil.

15. A composition as claimed in any one of claims 12 to 14 wherein the chlorine is present as calcium chloride.

16. A composition as claimed in any one of claims 12 to 15 wherein the calcium salt of the synthetic oil-soluble sulfonic acids

constitutes from 45 to 48 wt.% and the chlorine constitutes from 0.2 to 0.5 wt.%, the percentages being based on the weight of the composition. ~~~~~~~~~~~~~~~~~~~~~~~