DE1213825B - Process for the production of transparent, colloidal dispersions of calcium carbonate in oil - Google Patents

Description

Process for the production of transparent, colloidal dispersions of calcium carbonate in oil The invention relates to a method of manufacture of transparent dispersions of calcium carbonate in oils; especially colloids Dispersions in which the particle size is below about 0.1 [.

It is known in the lubrication of internal combustion engines and the like, that the formation of coal sludge deposits is connected with the oxidation of the oil and is accelerated by various catalysts. Come as catalysts in particular acids are considered here, which are formed in the oil by oxidation or which are absorbed by the oil, e.g. B. from the combustion of sulfur and halogen compounds in internal combustion engines. It is also known that -if the acids immediately are neutralized - the speed of coal sludge formation is greatly reduced can be so that the life of the oil in the engine is well beyond the life of a oil that is not protected by neutralizing agents can be extended. It is it has also been found that calcium carbonate is one of the most effective neutralizing agents for this purpose, as it is highly insoluble in water, reacts neutrally, but is able to neutralize all acids occurring in the lubricating oils, that are stronger than carbonic acid. It is therefore said that calcium carbonate Has "reserve alkalinity".

To take advantage of the valuable protective properties of calcium carbonate, it is necessary that the calcium carbonate in oil in such finely divided The condition is that it is the mode of operation of the engine in which the oil acts as a lubricant is used, does not bother. This makes it necessary that the particle size is sufficient is small so that the oil appears transparent to the naked eye. aside from that it is necessary that the oil can be easily filtered through the usual filter media, such as B. filter paper is. Accordingly, particle sizes are below 0.1 # desirable. When larger particles are present in the oil, they make the oil cloudy or cloudy, and there is also a great risk that the bearing surfaces will wear off and that the coarse particles will settle in the oil if you stand for a long time.

Numerous methods have already been described that are used for the production of a calcium carbonate to serve the above-mentioned properties. Most these methods consist in the fact that calcium carbonate is obtained from solutions of calcium salts precipitates in the presence of emulsifiers. Here, the emulsifiers act as Peptizers that agglomerate the particles and coagulate the emulsion impede. In the process of U.S. Patent 2,839,470, an emulsion is obtained of calcium hydroxide in a lubricating oil in the presence of an emulsifying agent such as e.g. B of an oil-soluble sulfonate, produced and from it by the action of carbon dioxide Calcium carbonate precipitated. In this process, water is essential, and it is it is also necessary to precisely control the amount of water added in order to achieve a satisfactory, to obtain transparent and filterable oil.

Another method avoids the presence of water through Use of alcohols, in particular lower alcohols with 1 to 6 carbon atoms. This method is described, for example, in U.S. Patent 2,865,956 and in U.S. Patent No. 2,865,956 Canadian Patent 574161. Calcium hydroxide, Oil and emulsifiers, such as. B. petroleum sulfonate or alkyl salicylate, with carbon dioxide treated. It has also been found in U.S. Patent 2,956,018 that, when calcium hydroxide with carbon dioxide in the presence of a lower alcohol with 1 up to 5 carbon atoms is treated, a complex compound can be obtained, those in a hydrocarbon oil containing a dispersant such as. B. Calcium sulfonate, contains, can be dispersed, the desired transparent dispersions from calcium carbonate. This process is mechanical with numerous Afflicted with difficulties, which consist in the fact that the particles have the tendency at to bake the heated surfaces and deteriorate, causing agglomeration occurs with the formation of undesirable large particles that are not present in lubricating oils and which are due to their practically non-filterable particle size must remove from the oil with great difficulty.

It has already been found earlier that when calcium oxide according to the method of U.S. Patent 2,865,956 is the only effective one Alcohol is methanol. It has also been found that when using calcium oxide the reaction must be carried out in the absence of water. Further it was found that the activity of calcium oxide depends to a large extent on its production method and that the calcium oxide obtained by roasting calcium hydroxide, that obtained by calcium obtained from calcium carbonate (limestone) at higher temperatures is much more effective than the common calcium oxide of commerce that is obtained by roasting calcium carbonate (Limestone), is usually obtained at a much higher temperature. The abbreviation For the sake of this, this process is referred to here as the "methanol process".

With this given prior art, the invention is based on a process for the production of transparent, colloidal dispersions of calcium carbonate in oil from where carbon dioxide in a suspension of active calcium oxide in anhydrous Introduced methanol and the reaction product with oil and an oil-soluble emulsifier is mixed. In a method of this type, there is now the characteristic of the present The invention consists in that finely divided calcium carbonate obtained by calcining Calcium oxide mixes with the anhydrous methanol, 5 to 50% of the amount used to convert the Oxyds in carbonate introduces the required amount of carbon dioxide, then the oil and the oil-soluble dispersant is added and further carbon dioxide is added with thorough mixing to complete the reaction, followed by the methanol by distillation is removed and the product is optionally treated with water and then is drained again. This way of working, which is marked in this way, has the great advantage that the activity of calcium oxide in the first phase of the reaction to a great extent is increased so that practically complete absorption in the second reaction phase of calcium oxide can be reached through the oil and water. This is why an essential advantage, since unreacted (undissolved) calcium oxide is filtered off from the oil must be, which causes high costs and extraordinary difficulties with especially if, after treatment with water, the oxide turns into a colloidal one Hydroxyd was transferred. Some of these suspensions of calcium hydroxide in oil, in particular with a particle size of 1 to 100, are practically unfilterable, if there are particles with a statistical size distribution.

It is therefore preferred, preferably only 10 to 30% of the stoichiometric quantities of carbon dioxide required to convert calcium oxide into calcium carbonate to be used, whereby the purity of the calcium oxide, which is usually 90 to 95% must be billed. In the case of pre-carbonization, the amount can of the methanol to one-half to twice the volume of the oil dispersant can be reduced without gel formation. After adding oil and dispersing agent there is no longer any fear of a further tendency to gel formation, and the reaction with The carbon dioxide proceeds rapidly as a result of the activating effect of the carbon dioxide treatment before adding the oil and the dispersant.

The calcium oxide should be ground so finely that it can pass through a sieve can be sieved with 40 meshes per centimeter. Even finer ground oxide, that a sieve with 79 or even 115 meshes per centimeter passes is even more more advantageous because it mixes more easily with the liquid reaction components: In - the activation stage of the procedure, the ratio of calcium oxide is to methanol usually 10 to 30 parts by weight of calcium oxide per 100 parts by weight Methanol.

In most cases this relates to the one according to the invention Process manufactured product based on dispersions of calcium carbonate in lubricating oils based on petroleum and mainly in oils in the range of engine oil viscosity SAE 5 up to SAE 60. However, other oils can also be used for special purposes. for example hydraulic oils with viscosities down to 100 Saybolt seconds at 38 ° C and synthetic hydrocarbon oils of polyolefin character, in particular Polypropylene and polybutylene. The procedure is also based on oils that are not made Hydrocarbons exist, applicable, for example to polyethers and esters. Of the latter, the esters of dibasic acids, for example dinonyl, Dilauryl and dioctyl adipate, azelate, sebacate, phthalate and the like are mentioned. The fat ones Oils such as B. fatty acid glycerides and glycol esters, can also according to the invention can be used as well as the esters of trimthylolpropane and similar polyfunctional ones Alcohols.

Preferred dispersants for the purposes of the present invention are oil-soluble sulfonates, especially petroleum sulfonates, which are usually called "mahogany sulfonates" are designated. Alkylnaphthalene sulfonates, such as. B. Dinonylnaphthalene sulfonate, can also be used as dispersants, as can the alkylbenzenesulfonates with at least 20 carbon atoms.

Alkylation products of benzene or naphthalene with olefins from the Thermal cracking of paraffin waxes can also be sulfonated and used as a dispersant can be used for the method of the invention. Alkyl salicylic acids with more than 20 carbon atoms are also suitable as dispersants, as are higher molecular ones Fatty acids, for example oleic acid, stearic acid, arachidonic acid and erucic acid. The naphthenic acids obtained by extracting petroleum with alkali are also suitable dispersants. The same applies to the resin acids, such as. B. Abientic acid, which are used in the form of their metal salts. Generally get Sulphonic acids, phosphonic acids and carboxylic acids with more than 12 carbon atoms and especially 20 to 60 carbon atoms are used.

Although the dispersants are in the form of free acids, which subsequently by which calcium oxide is neutralized in the process of the invention is used it is preferable to use the dispersants in the form of their metal salts, preferably used as calcium salts, although also Salts with Barium, magnesium, lithium or potassium are suitable. The amount of dispersant depends on the product to be obtained and to a large extent determines the final one Amount of calcium carbonate that can be introduced. So it was found that at Use of petroleum mahogany sulfonate in the form of calcium soap in one concentration from about 40% in the lubricating oil up to 33% calcium oxide can be introduced, an oil containing a sulphated ash content of approximately 50% is obtained. The sulphated ash is obtained by burning a sample of the oil in a known manner and obtained by treating the ash with an excess of sulfuric acid, wherein all calcium and other metals present in the final smoke be converted into sulfates.

Essential to the process of the invention is methanol, which is free of water and other alcohols. It was found that propyl alcohol and butyl alcohol, if they are present in small amounts, the methanol will poison and the reaction inhibit. Methanol that contains less than 1 percent water by volume is required and it is desirable that the water content does not exceed 0.5%. Of course the other substances used, such as the dispersant and the hydrocarbon solvent, be practically anhydrous.

When carrying out the method according to the invention, it is essential to work with thorough mixing. Because of the high viscosity of some of the oils used, it is desirable to increase the viscosity by adding a diluent, such as B. a petroleum-derived diluent or heavy gasoline to reduce. Numerous diluents can be used for this purpose, for example Stoddard thinner or kerosene. Because of the ease of removal through Distillation, however, it is generally recommended to use a gasoline that has a narrow boiling range, e.g. B. from about 120 to 150 ° C. An aromatic Hydrocarbon fraction obtained from petroleum and its volatility Xylene equivalent can also be used. Aromatic solvents such as z. B. benzene, toluene and xylene, and chlorine-containing solvents such as carbon tetrachloride and trichlorethylene, which are easily removed from the lubricating oil for reuse can also be used. Usually this will be the diluent used in amounts from 1/2 to 2 volumes of the volume of the oil to be processed.

The dispersant and the diluent are expediently with mixed with the oil before mixing with the methanol and calcium oxide. the The reaction is exothermic and it is therefore generally desirable to start the reaction to begin at a temperature below the boiling point of methanol in order to achieve the Reduce cooling needed during the process, especially when the reaction is carried out at atmospheric pressure. However, it is convenient to start the reaction at a temperature of 21 ° C or above, as the reaction starts at low Temperatures is usually too slow for practical use. cooling can either through a cooling coil or by evaporating the methanol from the Reaction, whereby the vapors are condensed and recovered for the process, take place.

Since it is necessary that the oil is clear and free of suspended solid components, a filtration is expediently carried out as the last stage, after the methanol and the diluent have previously been removed. Heating the oil to a temperature of 204 ° C is generally sufficient to remove the diluent, unless a very high boiling diluent, such as. B. kerosene was used. In the latter case, heating is in the. Vacuum recommended. To remove the diluent, it is also possible, if appropriate, to distill with steam. The filtration and clarification of the oil is expediently carried out by mixing with a suitable filter aid, such as. B. kieselguhr executed.

After the reaction of carbon dioxide, calcium oxide, oil, dispersant and methanol has ended and the methanol has been removed by distillation, it is recommended that the product be treated with water, usually hot water or steam. The water treatment, which is expediently carried out before the hydrocarbon diluent is removed, has the purpose of converting it into a type of oil-in-water emulsion and at the same time removing the methanol which appears to be combined with the calcium and dispersant. The water treatment has the beneficial effect of reducing the viscosity of the product which, without water treatment, often has gelatinous properties and sometimes turns into a grease-like solid on standing. The amount of water used is usually 1 to 20 percent by volume of the oil.

The following examples serve to illustrate the process according to the invention. Comparative Example 1 For this example, a calcium oxide was used which had been obtained by calcining limestone in a continuous shaft furnace at 1204 ° C. This oxide reacts very quickly with water to form calcium hydroxide. 30 g of the finely ground oxide were mixed with 100 cc of anhydrous methanol, 200 cc of gasoline (boiling point 121 ° C.) and 200 g of a calcium mahogany soap containing about 40% soap in a lubricating oil. The mixture was stirred rapidly while passing in a stream of carbon dioxide and maintaining the temperature at 49 to 54 ° C. As a result of the reaction, the temperature rose very slightly and the supply of carbon dioxide was continued for 2 hours. The mixture was then quickly filtered off on a suction filter and the methanol was evaporated from the filtrate by heating to a temperature of 104.degree. Water was added, the solvent was removed from the emulsion obtained and the mixture was dehydrated at 171 ° C. and the oil was finally filtered while it was still hot. When titrated with a standard acid solution, the alkali value was 1.4 (milligrams KOH per gram) with phenolphthalein as the indicator, and 124 with methyl orange as the indicator. The theoretical alkali value for this amount of oxide (15%) is 230. Only about 54% of the oxide reacts: under these conditions, if all the components of the mixture were mixed before the introduction of the carbon dioxide and no precarbonization of the oxide was used. These results show. that much of the calcium oxide used in the reaction was: inactive. COMPARATIVE EXAMPLE 2 The calcium oxide used was obtained by roasting limestone at a temperature of 13500 ° C. It showed the following analysis: aluminum oxide. . . . . . . . . . . . . . 0.5% Fe203 ....:. _. . "... '...... -. ....... 0.05% Ca0 .... -_ _...". . . . . . . . . . . ... . . . . 95.7% MgO. . :. . . . . . . . . . . 2.00 / 0 C03. . . . . . . . ... . . ... . . . . . . . . . ,, 0.31 / 0 silicon dioxide and insoluble fractions 07% The oxide was used up to a sieve fineness of. 115 stitches per. Milled centimeters and used in the following reaction: 25 g of the oxide were mixed with 150 cc of warm methanol; 100 g of: a calcium mahogany soap, containing about 3% soap in a lubricating oil, diluted with 100 cc were added Xylene and rapidly mixed with the oxide and methanol in a Waring turbine mixer while carbon dioxide was bubbled in. The temperature was held at 61.1 ° C. with high-speed mixing for 10 minutes. The speed was then reduced to half. and the introduction of the carbon dioxide continued for a further hour, during which the temperature dropped to 51.1 ° C. The mixture was then heated to 104 ° C. in a vessel on a stimulating plate to drive off the methanol; it was then filtered. The filtrate was not clear. It was filtered repeatedly using standard Super-Cel, then treated with water to form an emulsion and then dehydrated at 193 ° C. The oil was then filtered and titrated. The alkali value was 98 with methyl orange as an indicator, while the theoretical alkali value for the amount of calcium used is 329, which indicates that the oxide was only converted to about 30%. The oil was cloudy and, when diluted with heavy gasoline, gave a pulpy solution. Example 3 40 g (0.68 mol, based on 95% purity) calcium oxide were mixed with 150 cc of methanol and 75 cc of VM&P naphtha. With stirring, carbon dioxide was added to the mixture at a rate of 11 / min. For 1 minute The temperature rose from 51.6 to 60.0 ° C. 150 g of calcium mahogany soap (40% in 60% lubricating oil) were then quickly added to the activated oxide mixture and the mixture was diluted with 75 cc of gasoline, after 10 minutes Stirring with the introduction of carbon dioxide (11 / min.), The temperature rose to 64.0 ° C. and then fell. After 25 minutes, the reaction was complete. During the reaction, a further 50 cc of methanol were added and a further 100 cc of gasoline was added to reduce the - to compensate for losses caused by evaporation. — The mixture was heated on a hot plate with some difficulties caused by sticking and caking. At 93.3 ° C., when most of the methanol had evaporated, 25 cc was added Add water to break the coagulated gel chen, and received a thin emulsion. This was heated up to 129.4 ° C to remove the water. Subsequently, a clear solution was filtered, which was heated to 176.7 ° C. to remove the solvent, a clear red oil being obtained. The alkali value of this oil (indicator: methyl orange) was 256, which corresponds to 75% of theory (340). This shows the advantage that the calcium dioxide can be activated by means of carbon dioxide in methanol. The amount of carbon dioxide used for activation was 6.61 / o of the stoehiometric equivalent for the carbonization of the calcium oxide, Example 4 In this example, 9.3 kg of the same calcium oxide as in Example 13 were slurried in 37.851 anhydrous methanol. Carbon dioxide was introduced; to 2.27 kg were absorbed, the temperature rising to 57.8 ° C. Then 45.4 kg of a solution. a lubricating oil containing about 35% of a calcium mahogany sulfonate added, diluted with 75.71 xylene (solvent naphtha B). The supply of carbon dioxide was continued. The following samples were taken, which were filtered and worked up to a solvent-free oil: Total amount of the supplied alkali Carbon dioxide "methyl orange 3.36 kg 132 7.26 kg. 164 " 9.07 kg 192 " At the end of the reaction after 4 hours, the temperature dropped to 32.8 ° C. The end product was clear, could be filtered quickly and was gel-free. Activation of calcium oxide in methanol consumed 25% of the total amount of carbon dioxide used.

Example 5 To 118661 methanol and 139101 xylene; recovered from one of the preceding batches was added 1360 kg of calcium oxide (95% CaO) (obtained by calcining limestone at 1204 ° C.), ground so finely that it was sieved through a sieve of 115 meshes per centimeter could be. 181.4 kg of carbon dioxide was bubbled into the suspension with thorough mixing by centrifugal pumping the mixture from the bottom of the jar and back into the jar. The carbon dioxide was introduced into the circulation zone and was completely absorbed by the suspension over the course of 15 minutes. This corresponds to 18% of the stoichiometrically required amount for the conversion of the oxide into the carbonate. 9712.31 of a solution of calcium mahogany sulfonate in oil, diluted with 50% xylene, were then added to the suspension of the activated oxide. The solution of the sulfonate in the lubricating oil (4856.11) contained 35% calcium sulfonate. The addition time was approximately 5 minutes. Carbon dioxide was then passed into the mixture over the course of 55 minutes until a total of 635 kg of carbon dioxide had been added. The temperature rose from 26.7 to 60.0 ° C. during this process. It was therefore cooled in order to avoid distilling off the methanol. At the end of the reaction, the methanol was distilled off by heating to 135 ° C., a portion of the xylene being removed at the same time, which enabled the methanol to be completely distilled off. The distillate contained 26-28% xylene. The reaction mixture was then cooled to 87.8 ° C. 2651 water was added to break the gel structure in the product. The water was then removed by heating to 121 ° C., the product was cooled and filtered with the aid of kieselguhr. The clear solution of the oil was then heated and treated with steam to remove the solvent. The resulting oil had an alkali value of 7 with phenolphthalein as an indicator and 265 with methyl orange as an indicator. The specific weight was 1.08 corresponding to 4.08 kg / 3.7851. EXAMPLE 6 A stream of carbon dioxide was passed into a mixture of 200 cc of methanol and 30 g of calcium oxide obtained by calcining limestone and ground to a sieve fineness of 115 meshes per centimeter. for a period of 2 minutes. The temperature rose from 32.2 to 47.2 ° C. 100 g of a 35% strength solution of calcium mahogany sulfonate in lubricating oil, which had been diluted with 100 cc of xylene, were then added to the batch. Vigorous stirring of the mixture was continued while the carbon dioxide was bubbled in. The temperatures observed are given below. Time in minutes 1 (3 I 7 1 9 13 Temperature, ° C ...... 53.3 57.8 62.2 60.0 48.9 Additional xylene was added during the reaction as soon as the mixture thickened.

13 minutes after adding the sulfonate to the pretreated lime and Methanol, the methanol was evaporated by heating to a temperature of 98.9 ° C. Then 30 cc of water was added with stirring. The thick oil granulated immediately and then turned into a thin liquid emulsion, which through Heating could be dehydrated without gelling. The oil was at 204.4 ° C with Filtered with the help of diatomaceous earth. Alkali versus phenolphthalein 33, versus Methyl orange 343. Theoretical value for calcium oxide of 95% purity 370; percentage Calcium oxide consumption 93.4 0/0.

An oil is not understood here to mean a viscous liquid that immiscible with water and animal, mineral, vegetable or synthetic Can be of origin.

If the methanol is removed from the reaction mixture, it is sometimes desirable to mix by introducing hydrocarbon vapors, such as B. Vapors of VM&P naphtha or xylene to be avoided, being avoided the product must stick to the hot surfaces, sometimes before the water treatment can happen. Paraffinic gasoline is not completely miscible with methanol. Therefore, the methanol layer can be easily separated and used again.

In a device for continuous activation, it is advisable to prepare a slurry of calcium oxide in methanol, e.g. From 36.3 kg to 378.5 liters, and to introduce carbon dioxide into the stream of the slurry while the slurry is pumped through a mixer and a reaction vessel containing oil and a dispersant. In this way, the activation stage can be carried out in a few seconds, for example 5 to 300 seconds, and the risk of gel formation before the oil is added is also avoided. The carbon dioxide can be added in the form of a gas or a liquid. In the latter case, the liquid gasifies immediately on contact with the suspension of calcium oxide in methanol, and part of the heat of reaction is absorbed by the latent heat of vaporization of the carbon dioxide. The activation reaction can be easily controlled by increasing the temperature, usually about 16 to 32 ° C.

Claims (4)

Claims: 1. Process for the production of transparent, colloidal Dispersions of calcium carbonate in oil by introducing carbon dioxide into a Suspension of active calcium oxide in anhydrous methanol and mixing of the reaction product with oil and an oil-soluble emulsifier, characterized in that finely divided, calcium oxide obtained by calcining calcium carbonate with the anhydrous Methanol mixes, 5 to 50% of the amount needed to convert the oxide to carbonate Amount of carbon dioxide introduces, then the oil and the oil-soluble dispersant added and, with thorough mixing, further carbon dioxide to complete it initiates the reaction, whereupon the methanol is removed by distillation, and if necessary, the product is treated with water and then dehydrated again will. 2. The method according to claim 1, characterized in that as a dispersant a calcium salt of an oil-soluble sulfonic acid is used. 3. Procedure according to Claim 1, characterized in that a hydrocarbon diluent in is added in such an amount that the viscosity of the oil is reduced. 4. The method according to claim 1, characterized in that to 10 to 30 parts by weight Calcium oxide applies 100 parts by weight of methanol, when using calcium mahogany -Sulfonate as a dispersant, a weight ratio of oxide to oil and sulfonate of approximately one fifth to one third and water in amounts of 1 to 20 percent by volume, based on the oil, adds. Publications considered: German Auslegeschriften No. 1142 851, 1063 587; French Patent No. 824 842; USA: patents No. 2 956 018, 2 865 956.