RU2259993C1 - Method for preparing calcium stearate - Google Patents

Abstract

FIELD: chemical technology.

SUBSTANCE: invention relates to a method for preparing calcium stearate used for stabilization of plastic masses, in manufacture of paint and varnish materials, vitamin and medicinal preparations. Preparing calcium stearate is carried out by interaction of stearic acid and calcium oxide or hydroxide in the equimole ratio of reagents. The process is carried out in the solid phase under atmosphere pressure and intensive stirring without heating in the presence of zeolite of CaX type taken in the amount 6.7-16 wt.-%. Method provides simplifying technology due to a single stage process and improvement of economical indices.

EFFECT: improved preparing method.

7 tbl, 3 ex

Description

The invention relates to a method for producing calcium stearate used to stabilize plastics based on polyvinyl chloride, perchlorovinyl resin and artificial leather. In addition, calcium stearate is used as a desiccant in the manufacture of paints and varnishes, for the production of vitamins and medicines.

A known industrial method for producing calcium stearate. The method includes the following steps:

1. Obtaining the sodium salt of stearic acid by reaction

C ₁₇ H ₃₅ COOH + NaOH -> C ₁₇ H ₃₅ COONa + H ₂ O

2. Obtaining calcium stearate by the exchange reaction of sodium stearic acid and calcium chloride

2С ₁₇ Н ₃₅ COONa + CaCl ₂ -> (С ₁₇ Н ₃₅ COO) ₂ Са + 2NaCl

3. Washing the suspension of calcium stearate.

4. Drying of calcium stearate in a vacuum-row dryer.

[Technological regulation "Production of calcium stearate No. 123-01-90, Sterlitamak"]. Using this technology, calcium stearate is obtained at the Luminofor plant in Stavropol and the chemical plant in Kineshma.

The disadvantages of this method are:

1. The complexity of the technology due to the two-stage process and the formation of a large amount of wastewater. 2588 kg of wastewater containing about 200 kg of mineral salts are formed per 1 ton of finished product.

2. The energy intensity of the process due to the presence of the drying stage under vacuum.

3. Irreversible loss of caustic soda in the form of NaCl discharged by wastewater, which leads to unjustified increase in the cost of the method and environmental degradation of the method.

A known method of producing calcium stearate [RF Patent 2124495, 01/10/99. bull. No. 1].

The essence of the known method is as follows:

1. Stearic acid is pre-dissolved at 70-75 ° C in a 4-6-fold excess relative to the mass of stearic acid in an aqueous-alcoholic solution with a volume ratio of alcohol: water (1.5 ... 0.5) :( 0 , 5 ... 1,5), respectively. As an alcohol-water solution, solutions of C ₁ -C ₄ alcohols are used, the dissolution time is 30-40 minutes.

2. The resulting mixture is subjected to interaction with an 18-25% aqueous solution of calcium hydroxide. The molar ratio of stearic acid and an aqueous solution of calcium hydroxide 2: (1.3 ... 1.5). The reaction time is 2 hours.

3. The finished product with an acid number of 2 mg KOH / g is filtered off, washed with water and dried with hot air at 80-90 ° C. The product yield is 99.2%.

The disadvantages of this method are:

1. The complexity of the technology due to the multi-stage synthesis, including: the dissolution of stearic acid in alcohol, the stage of synthesis of calcium stearate, the stage of filtration and the stage of drying of the finished product.

2. Irretrievable losses of the alcohol-water solution and the process in excess of calcium hydroxide lead to a rise in the cost of the process. In the known method does not indicate the possibility of reuse of alcohol-water solution. If we assume the reuse of alcohol-water solution, then there is a need for solvent regeneration, which is associated with losses and complication of the process.

3. The energy intensity of the process due to the presence of the stage of drying of the finished product.

The closest in technical essence and the achieved result is a method of producing calcium stearate by the interaction of stearic acid and calcium hydroxide by heating and vigorous stirring. The peculiarity of the method consists in carrying out the process in the presence of a solvent, acetone or a water-acetone mixture (with an acetone content of at least 25% (mass.)) Taken in a 4-6-fold excess relative to the mass of stearic acid with an equimolar ratio of stearic acid and hydroxide calcium at a temperature of 40-50 ° C.

The reaction time is 1 hour. After synthesis, the reaction mass is cooled, filtered under vacuum and dried in an oven at a temperature not exceeding 100 ° C [RF Patent 2156758, C 07 C 51/41, 53/126, 09/27/2000. Bull. No. 27].

The disadvantages of this method are:

1. The complexity of the technology, due to the multi-stage process (synthesis of calcium stearate; filtering the reaction mass; drying the finished product). In addition, an explosive solvent, acetone, is used in the process.

2. The energy intensity of the process associated with the stage of drying of calcium stearate and the need to heat the reaction mass to a temperature of 40-50 ° C.

3. Irreversible loss of solvent - an aqueous solution of acetone, because the method does not involve the reuse of an aqueous solution. Even in the case of reuse of the solvent, there is a need for regeneration of the solvent, which leads to loss of solvent and the complexity of the technology.

4. The duration of the process. The reaction time is 1 hour. In addition, the process time is increased due to the presence of a drying step.

Drying calcium stearate is time consuming and energy intensive. Although the prototype does not indicate the drying time, according to the authors of the invention, it is 3-4 hours under vacuum, depending on the water content in the paste.

5. Insufficient raw material base (use only stearic acid and calcium hydroxide).

The objective of the invention is the simplification of technology, the intensification, cheaper process and the expansion of the raw material base for the production of calcium stearate.

EFFECT: one-step synthesis, simplification of the process technology by eliminating the stages of preparation of reagents and filtering the resulting product, reducing the energy intensity of the process by eliminating the heating of the reaction mass and drying of the finished product, eliminating the use of explosive substances.

The specified technical result in the implementation of the invention is achieved by the fact that in the known method for producing calcium stearate by the interaction of stearic acid and calcium oxide or hydroxide with an equimolar reagent ratio and intensive stirring, the feature is that the process is carried out in the solid phase without heating in the presence of a CaX type zeolite adsorbent in the amount of 6.7-16% (mass.).

The method is as follows.

The synthesis of calcium stearate is carried out in a 62-ML laboratory ball mill, which has the following characteristics: usable volume - 1 l, initial material fineness - (0-3) mm, final material fineness - less than 0.075 mm, weight of loaded balls - 1.5-2 kg, the diameter of the balls is 12-20 mm, the diameter of the drum is 150 mm, the length of the drum is 100 mm and the rotation speed of the drum is 112 rpm.

The quality of the CaX zeolite used in the synthesis corresponds to TU 38.10281-88 and has the following chemical composition: Al ₂ O ₃ - 33% (mass.), SiO ₂ - 49.7% (mass.), Na ₂ O - 8.9 % (mass.), CaO - 8.4% (mass.). The calcium content in the zeolite is 6.0% (mass.). Static absorption capacity in water - 29.4% (mass.). Density - 3000 kg / m ³ .

Quality of stearic acid, corresponds to GOST 6484-96, and has the following characteristics: Appearance - White powder, transparency at a temperature of 70 ° C - Transparent, Iodine number - J 3 g _2/100 g, mass fraction neomylyamyh substances - 0.5% (w .), pour point - 69 ° С, acid number - 201 mg KOH / g, saponification number - 204 mg KOH / g, mass fraction of moisture - 0.1% (mass.).

Calcium hydroxide is used with a basic substance content of 99.2% (mass.).

Calcium oxide is used with a basic substance content of 99.5% (mass.).

The method involves the use of the above reagents with other quality indicators.

1. Scheme of the process using stearic acid, calcium hydroxide and CaX zeolite

The reaction water released during the synthesis adsorbs CaX zeolite, thereby achieving a double effect: there is no need to dry calcium stearate and the reaction time is reduced due to a shift in the reaction equilibrium towards the formation of reaction products due to a decrease in the concentration of water in the reaction zone.

2. Scheme for the synthesis of calcium stearate when using stearic acid, calcium oxide and CaX zeolite:

Zeolite CaX works similarly to the description in paragraph 1.

The estimated amount of stearic acid and calcium oxide or hydroxide are charged to the reactor. The amount of CaX zeolite is calculated depending on the amount of reaction water and the static water adsorption capacity of the zeolite. The reactor is sealed. The synthesis is carried out for 30 minutes with vigorous stirring. After the product is unloaded and analyzed for compliance with TU-6-22-05800165-722-93 or the requirements given in the reference book "Chemical additives to polymers" - M .: Chemistry, 1973, p.126 (see table 1).

Get 4 samples with different quality indicators. The results of the analysis are shown in table 2.

As can be seen from table 2, the quality indicators of calcium stearate of all four samples meet the requirements of TU 6-22-05800165-722-93 and the requirements given in the reference book "Chemical additives to polymers" - M .: Chemistry, 1973, p.126.

Table 1. Name of indicator Norms TU 6-22-05800165-722-93 The requirements given in the directory "Chemical additives to polymers" - M .: Chemistry, 1973, p.126. Top grade First grade 1. Appearance Homogeneous white powder without fur. impurities Homogeneous powder with a yellowish tint without fur. impurities White or slightly yellowish powder, insoluble in water 2. Mass fraction of Ca ²⁺ , NB 6.0-6.8 5.8-6.8 6.0-7.0 3. Acid number, KOH / g, n.b. 2.0 2,5 2.0 4. Mass fraction of moisture,%, n.b. 3.0 3.0 1 5. Udel. electrical conductivity of water extract, cm / m at 25 ° С, n.b. 0.05 0.06 0.05 6. Melting point, ° C, within - - 125-140 7. The remainder on the sieve No. 0315,%, NB - - 0.5 Table 2. Name of indicator Prototype Calcium Stearate No. 1 Number 2 No. 3 Number 4 1. Appearance Homogeneous white powder without fur. impurities 2. Mass fraction of Ca ²⁺ , NB 6.0 6.0 6.0 6.0 3. Acid number, KOH / g, n.b. 1.7 1.3 1,5 1,1 4. Mass fraction of moisture,%, n.b. 2,5 0.9 2.9 0.8 5. The plot. electrical conductivity of water extract, cm / m at 25 ° С, n.b. 0.05 0.05 0.05 0.05 6. Melting point, ° C, within - 138 - 137 7. The remainder on the sieve No. 0315,%, NB - 0.1 - 0.1

Note.

1. A prototype of calcium stearate No. 1 was obtained by the interaction of stearic acid and calcium hydroxide, taken in an equimolar ratio, in the presence of 10.3% (mass.) Of CaX zeolite. Ambient temperature 18 ° С.

2. A prototype of calcium stearate No. 2 was obtained by the interaction of stearic acid and calcium hydroxide, taken in an equimolar ratio, in the presence of 16% (wt.) Zeolite CaX. Ambient temperature 22 ° С.

3. A prototype of calcium stearate No. 3 was obtained by the interaction of stearic acid and calcium hydroxide, taken in an equimolar ratio, without using CaX zeolite. The reaction time is 1.8 hours. Ambient temperature 22 ° С.

4. A prototype of calcium stearate No. 4 was obtained by the interaction of stearic acid and calcium oxide, taken in an equimolar ratio, in the presence of 6.7% (mass.) Of CaX zeolite. Ambient temperature 25 ° C.

Calcium stearate according to TU-6-22-05 800165-722-93 is used as a heat stabilizer in the processing of polyvinyl chloride. Therefore, further obtained prototypes of calcium stearate that meet the requirements of TU were tested in various processes for processing PVC resins. The test results of the prototypes of calcium stearate are presented in tables 3-6. Prototypes were tested in the formulations of PVC films and in the formulations of cable compounds.

Table 3.
Test results of prototypes of calcium stearate in the formulation of PVC film for greenhouses and greenhouses. Name of indicator Norm according to TU 2293-393-00203447-99 Calcium stearate according to TU 6-22-05800165-722-93 Prototype Calcium Stearate No. 1 Number 2 No. 3 Number 4 1. The tensile strength, MPa (kgf / cm ² ) along 15,2 328 337 331 330 332 (155) across 13,2 270 275 271 270 272 (135) 2. The relative elongation at break,%, nm 170 276 3. The temperature of brittleness, ° C, not higher minus 35 -35 -35 -35 -35 -35 4. Transmittance,%, not less 80 88 86 87 88 87 5. Thermostability at 170 ° C, min - 32 41 45 35 38

Table 4.
The test results of prototypes of stearate in the formulation of plasticized PVC film technical GOST 16272-79. Name of indicator Norm for brand OH, premium Calcium stearate according to TU 6-22-05800165-722-93 Prototype Calcium Stearate No. 1 Number 2 No. 3 Number 4 1. Elongation at break,% not less 200 241 227 220 240 221 2. The temperature of brittleness, ° C, not higher -20 -25 -25 -25 -25 -25 3. Thermostability at 170 ° C, min - thirty 45 45 45 45 4. Tensile strength, MPa (kgf / cm ² ), not less than along 18.0 (183) 207 215 211 208 212 across 15 (153) 100 103 102 100 101 Table 5.
The test results of prototypes of stearate in the formulation of PVC compound for insulation and protective shells of wires and cables GOST 5960-72. Name of indicator Norm for brand I40-13 Calcium stearate according to TU 6-22-05800165-722-93 Prototype Calcium Stearate No. 1 Number 2 No. 3 Number 4 1 2 3 4 5 6 7 1. Specific volume electric resistance at 20 ° С, Ohm · cm, not less 1 · 10 ¹³ 6.410 ¹³ 5.710 ¹³ 5.510 ¹³ 6.210 ¹³ 5.710 ¹³ 2. Specific volume electric resistance at 70 ° С, Ohm · cm, not less 2 · 10 ¹⁰ 4.210 ¹¹ 1.2 · 10 ¹¹ 1.710 ¹¹ 3.7 · 10 ¹¹ 1.810 ¹¹ 3. Tensile strength, MPa (kgf / cm ² ), not less 17.6 (180) 24.0 26.0 27,2 24.0 26.2 4. Relative elongation at break,%, not less 200 326 310 301 320 305 Continuation of table 5. 1 2 3 4 5 6 7 5. The temperature of brittleness, ° C, not higher -40 -40 -40 -40 -40 -40 6. Losses in mass at 160 ° C for 6 hours,% no more 2.0 1.91 1.8 1.8 1.8 1.8 7. Light fastness at 70 ° С, h, not less 1000 1000 980 980 1000 980 8. Flammability: method A, s, no more, method B,% thirty 5 4 4 4 4 9. Hardness at 20 ° C, 1.47 1.49 1.4 1.4 1.48 1.4 MPa (kgf / cm ² ), not less (fifteen) 10. Hardness at 70 ° C, 0.78 0.78 0.7 0.7 0.78 0.7 MPa (kgf / cm ² ), not less (8) 11. Water absorption,% no more 0.32 0.11 0.3 0.3 0.12 0.3 12. Softening point, ° C 180 ± 10 173 180 180 173 180 13. Density, g / cm ³ 1.27-1.35 1.28 1.3 1.3 1.28 1.3 14. Color fastness in a vesometer at 70 ° С, h, not less 96 96 98 98 96 98 15. Preservation of relative elongation at break after exposure at (100 ± 2) ° С for 7 days,% not less 75 95 90 90 94 91 Table 6.
Test results of prototypes of stearate in the formulation of PVC compound for insulation and protective sheaths of wires and cables GOST 5960-72 grade 0-40, premium. Name of indicator Norm for brand 0-40, premium Calcium stearate according to TU 6-22-05800165-722-93 Prototype Calcium Stearate No. 1 Number 2 No. 3 Number 4 1 2 3 4 5 6 7 3. Specific volume electric resistance at 20 ° С, Ohm · cm, not less 5 · 10 ¹⁰ 5.710 ¹² 4.210 ¹² 4.210 ¹² 5.010 ¹² 4.010 ¹² Continuation of table 6 1 2 3 4 5 6 7 4. Tensile strength, MPa (kgf / cm ² ), not less than 14.7
(150) 178 180 180 178 180 5. Elongation at break,%, not less than 300 361 358 358 360 358 6. Fragility temperature, ° С, not higher -40 -40 -40 -40 -40 -40 7. Losses in mass at 160 ° C for 6 hours,%, no more 3.0 1.65 1,52 1,50 1,67 1,52 8. Light fastness at 70 ° С, h, not less 1500 1500 1480 1480 1500 1480 9. Flammability: method A, s, no more, method B,% thirty 4 3 3 4 3 10. Hardness at 20 ° С, MPa (kgf / cm ² ), not more than 0.88-1.47
(9-15) 0.5 0.6 0.6 0.5 0.6 11. Hardness at 70 ° C, MPa (kgf / cm ² ), not more than 0.58-0.98
(6-10) 0.68 0.7 0.75 0.67 0.7 12. Water absorption,%, no more 0.35 0.11 0.2 0.2 0.12 0.2 13. Softening point, ° C 170 ± 10 165 170 170 165 170 14. Density, g / cm ³ 1.22-1.33 1.35 1.36 1.36 1.35 1.36 15. Tear resistance, kN / m (kgf / cm), not less 44.1 (45) 70 71 71 70 71 16. Color fastness in a vesometer at 70 ° C, h, not less 96 96 97 97 96 97 17. Preservation of elongation at break after exposure at (100 ± 2) ° С for 7 days,%, no less than 80 97.1 98 98 97.0 98

As the test results show, the calcium stearate obtained according to the invention is not inferior to calcium stearate according to TU and can be used as a heat stabilizer in the processing of PVC resin.

Example 1. The example shows the implementation of the process using calcium hydroxide. In a ball mill load 500 g of stearic acid with an acid number of 205 g KOH / g and 65.6 g of technical calcium hydroxide. The content of Ca (OH) ₂ is 99.2%. The reagent ratio is equimolar. Next, 65.0 g of CaX zeolite, which is 10.3% of the total reaction mass, is loaded into the mill. The amount of zeolite is calculated based on the amount of reaction water released during the process. Under conditions of 100% conversion of Ca (OH) ₂ , 31.64 g of water is released during the reaction, which is 5.6% (mass.) Of the reaction mass. According to TU 6-22-05800165-722-93, the moisture content in calcium stearate should not exceed 3% (mass.). Based on this, it is necessary to adsorb about 3% (mass.) Of moisture during the process, which is about 17.0 g. The adsorption capacity of the zeolite in water is 29.4% and the amount of loaded zeolite is 65.0 g.

After loading the components, the reactor is sealed and the reaction mass is stirred for 35 minutes. The reaction is carried out at atmospheric pressure and room temperature at 18 ° C. A white powder is obtained without mechanical impurities. The acid number of the obtained product is 1.7 g KOH / g, which indicates the end of the synthesis. The product yield is quantitative and the quality corresponds to TU 6-22-05800165-722-93.

Example 2. The example shows the implementation of the process using calcium oxide. 500 g of stearic acid with an acid number of 205 g KOH / g and 49.6 g of technical calcium hydroxide are charged into a ball mill. The CaO content is 99.5%. The reagent ratio is equimolar. Next, 39.0 g of CaX zeolite, which is 6.6% of the total mass of substances loaded into the reactor, are loaded into the mill.

Under these conditions, as a result of the interaction of stearic acid and calcium oxide during the complete conversion of the reagents, about 16 g of water is released, which is 2.9% of the weight of the loaded stearic acid and calcium oxide.

According to the requirements given in the directory "Chemical additives to polymers" - M .: Chemistry, 1973, p. 126, the moisture content should not exceed 1% (mass.), Therefore, it is necessary to adsorb 2% (mass.) Of moisture, which is 11 , 0 g of water.

For adsorption of 11.0 g of water, given the static adsorption capacity of the CaX zeolite, the amount of zeolite loaded is 39.0 g (6.6% of the total weight of the loaded reagents).

After loading the components, the reactor is sealed and the reaction mass is stirred for 16 minutes. The reaction is carried out at atmospheric pressure and room temperature 25 ° C. A white powder is obtained without mechanical impurities. The acid number of the obtained product is 1.6 mg KOH / g, which indicates the end of the synthesis. The product yield is quantitative and the quality corresponds to TU 6-22-05800165-722-93.

Example 3. The example shows the influence of the mixing time of the reaction mass on the performance of the process. The process is carried out analogously to examples 1 and 2. The results are summarized in table 7.

Table 7. Mixing time min Acid number, mg KOH / g of the product obtained on the basis of Ca (OH) ₂ Acid number, mg KOH / g of CaO-based product 5 180.0 170.0 10 90.0 110.0 fifteen 45.0 61.0 twenty 1.7 28.0 25 8.0 11.0 thirty 2.9 3.0 35 1.9 2.0 40 1,1 1,1

As can be seen from the results, the mixing time affects the degree of conversion (as judged by the decrease in acid number). Under these conditions, the reaction time of 30-35 minutes is optimal.

The advantages of the proposed method:

1. The process is carried out in one stage, raw materials are loaded into the reactor and the finished product is unloaded.

2. The energy intensity of the process is reduced, because the process is carried out without heating the reaction mass and there is no need for an energy-intensive stage of drying the finished product.

3. The reaction time is reduced by 1.7-2 times, which leads to an intensification of the process.

4. The raw material base of the process is expanding, i.e. it becomes possible to use calcium oxide in the process.

Claims (1)

The method of producing calcium stearate by the interaction of stearic acid and calcium oxide or hydroxide with an equimolar reagent ratio and vigorous stirring, characterized in that the process is carried out in the solid phase at atmospheric pressure and a temperature of 18-25 ° C in the presence of a CaX type zeolite in the amount of 6.7- 16 wt.%.