RU2385332C2 - Method of producing alkyd resin - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: alkyd resin is obtained using wastes from the pulp and paper industry - distilled tall oil, its fatty acids, a mixture of tall oil with sunflower oil 4-5:1, by reacting them with glycerin or pentaerythritol. The acidic component used is a mixture of terephthalic acid with partially oxidised intermediate products of oxidation of p-xylene (mixture of organic acids, wastes from production of purified terephthalic acid). Production wastes contain the following in wt %: terephthalic acid - 80-85, p-toluic acid - 8-15, benzoic acid - up to 0.4; 4-carboxybenzaldehyde - up to 0.1, the rest-water. The reagents are loaded at the same time. The process is carried out at 250-255°C with release of reaction water through a fusion method.

EFFECT: method enables use of wastes from production of terephthalic acid, which reduces cost of the end product, obtaining alkyd resin in a single step, cutting overall synthesis time to 5 hours while preserving operational characteristics of the resin.

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Description

The invention relates to the synthesis of alkyd resin, which is used as the basis for the manufacture of paints and varnishes.

A known method of producing alkyd resins by alcoholysis of vegetable oils with polyhydric alcohols, followed by the interaction of the products of alcoholysis with dibasic acid or its anhydride [1].

The disadvantage of this method is the long duration of the process, its two-stage process, as well as the use of expensive edible vegetable oils, which leads to an increase in the cost of the final product.

Known [2, 3] is a method for producing alkyd resins, in which the one-stage fatty acid method is used, which provides for the simultaneous loading of all components.

The limited application of this method in industry is associated with the need to use, instead of vegetable oils, unsaturated fatty acids previously obtained by splitting oils. The main disadvantage of [3] is the use of azeotropic distillation of reaction water, which is complicated in hardware design and requires an additional solvent, xylene.

Closest to the claimed invention is a method [4], which provides for the alkyd resin by the interaction of vegetable oils, phthalic anhydride, pentaerythritol when heated to 240-280 ° C with azeotropic distillation of water, distilled tall oil is used as vegetable oil, maleic anhydride is additionally introduced to speed up the process.

The main disadvantage of the prototype method is the use of additional reagents - maleic anhydride to intensify the process, xylene - for azeotropic withdrawal of water, high fat content of the obtained alkyd (> 70%). Also, the authors of this work were not able to carry out the synthesis with simultaneous loading of the starting components, since in this case, even with an acid number of 38 mg KOH / g, the resin was gelled. A satisfactory resin was obtained during the synthesis in two stages.

The objective of the invention is to optimize the composition of alkyd resin while maintaining the performance of its solution in a mixture of organic solvents (alkyd varnish), such as color, viscosity, dry residue, as well as drying speed, hardness and elasticity of the film based on the obtained varnish.

This object is achieved by the fact that in the claimed method for producing alkyd resin, the waste from the pulp and paper industry is used as vegetable oil — distilled tall oil and its fatty acids, as well as a mixture of tall oil with sunflower oil in a ratio of 4 ÷ 5: 1; glycerol and pentaerythritol as the polyhydric alcohol, a mixture of terephthalic acid with unoxidized intermediate products of p-xylene oxidation (a mixture of organic acids - JUICE), which is formed in the process of obtaining purified terephthalic acid and, in fact, is a production waste.

JUICE has the following composition, wt.%:

- terephthalic acid - 80-85;

- p-toluic acid -8-15;

- benzoic acid - up to 0.4;

- 4-carboxybenzaldehyde - up to 0.1;

- the rest is water.

The process is carried out at a temperature of 250-255 ° C with simultaneous loading of the starting reagents with the conclusion of the reaction water by fusion.

All experiments are carried out in a four-necked flask equipped with a stirrer, a thermometer, a reflux air cooler, an inert gas supply, and electric heating. The inert gas is supplied until the synthesis is completed and when the resin is mixed with the solvent.

The invention is illustrated by the following example.

The polyol, JUICE and oil component are loaded into the flask, include mixing and electric heating. The temperature is increased to 250-255 ° C, the reaction mass is maintained to an acid number of not more than 15 mg KOH / g and a satisfactory viscosity of a 50% solution of the resin in a mixture of organic solvents.

Upon completion of the synthesis and cooling of the alkyd to ~ 180 ° C, a 50% solution of the resin in a white spirit: solvent solvent mixture (1: 1) is prepared, its viscosity is measured according to VZ-4, and the color is evaluated on an iodometric scale. Coatings for tests are prepared by applying alkyd resin solutions in a mixture of solvents with a desiccant ZhK-1 to metal plates (up to 3% by weight of varnish). After application by dipping, the varnish coatings are dried at a temperature of 20 ° C for 24 hours, after which they are tested.

Tables 1 and 2 summarize the resin formulations and the norms of the technological regime, table 3 presents the test results of varnish coatings.

Table 1 Alkyd Resin Formulations Components Recipe one 2 3 four 5 Sunflower oil - 12 - - - Tall oil 52 40 - - 60 Tall Oil Fatty Acids - - fifty 60 - JUICE thirty thirty thirty twenty twenty Glycerol eighteen eighteen twenty - - Pentaerythritol - - - twenty twenty

table 2 Technological standards Indicators Recipe one 2 3 four 5 Polycondensation temperature, ° С 250 250 252 255 255 The duration of the polycondensation, h 3,5 3 5 5 5 The viscosity of a 50% solution in a mixture of white spirit - solvent according to VZ-4, s 102 71 62 65 68 Acid number, mg KOH / g 13.3 9,4 8.5 4,5 7.4 Color of a 50% solution in a mixture of white spirit - xylene at MHI mg J _2/100 cm ³ 60 40 40 twenty 40 Table 3 Alkyd Resin Coatings No. p / p Indicators Recipe one 2 3 four 5 one The appearance of the film Transparent Transparent Transparent Transparent Transparent 2 Drying up to st. 3 in 24 hours at 20 ° С Full Full Full Full Full 3 The hardness of the coating according to the pendulum device type TML, conv. units 0.11 0.14 0.10 0.10 0.10 four The elasticity of the film in bending, mm one one one one one 5 Film adhesion, points one one one one one

Based on the obtained varnishes, a primer according to the recipe GF-021 and white enamel - PF-115 were prepared. The test results of the obtained coatings are shown in table 4.

Table 4 Testing results of paints and varnishes No. p / p Indicators Primer Enamel one Appearance - After drying, the film forms a smooth, uniform surface without peeling, pocking, sagging, wrinkles and foreign particles. 3 Adhesion points one one four Drying time to st.3 at 20 ° C 24 24 5 Mass fraction of nonvolatile substances,% 68,2 67.8 6 Conditional viscosity at 20 ° С according to VZ-246, s 120 145 7 The elasticity of the film in bending, mm one one 8 Resistance at 20 ° C to static. exposure to water, h - 24 9 Resistance at 20 ° C to static. the effect of a 3% solution of sodium chloride, h 24 - 10 Resistance at 20 ° C to static. exposure to mineral oil, h 48 - eleven Resistance at 20 ° C to static. exposure to transformer oil, h - 48 12 Resistance at 20 ° C to static. exposure to a 0.5% solution of detergent, min - fifteen 13 The hardness of the coating according to the pendulum device type TML 2124 (pendulum A), rel. units 0.14 0.14

The advantages of the proposed method compared to the prototype are:

1) the use of RNS, a waste product of TPA, as a dibasic acid component instead of phthalic anhydride, which significantly reduces the cost of the final product;

2) obtaining alkyd resins in one stage;

3) the synthesis with the withdrawal of reaction water by the method of fusion, which does not require the introduction of an additional solvent, is simpler in design and maintenance, and also requires less energy.

In addition, the total synthesis time is reduced to 5 hours; the polycondensation temperature with the participation of TPA decreases to 250-255 ° C with its full involvement in the synthesis; losses caused by sublimation of the acid component are reduced; formation of a precipitate in the final product due to the complete conversion of the dibasic acid is excluded. The polycondensation reaction proceeds more deeply, without fear of the onset of gelatinization. The economic effect of the proposed method is obtained by replacing expensive vegetable edible oils with waste from the pulp and paper industry.

Alkyd resins obtained by the proposed method are light and transparent.

Bibliography

1. Solomon D. Chemistry of organic film formers. M .: Chemistry, 1971 - 319 p.

2. Okhrimenko I.S., Varholantsev V.V. Chemistry and technology of film-forming substances. - L .: Chemistry, 1978 - 392 p.

3. AC No. 1183509, C08G 63/50.

4. RU No. 2266921, C08G 63/49, 63/91.

Claims (1)

A method of obtaining an alkyd resin by the interaction of vegetable oil, polyol and an acid component, which consists in the fact that tall oil fatty acids, distilled tall oil and a mixture of tall oil with sunflower oil in a ratio of 4-5: 1 are used as vegetable oil as a polyol - pentaerythritol, glycerin, as an acid component - waste production of purified terephthalic acid, which is a mixture of terephthalic acid with unoxidized intermediate oxidation products of p- xylene (SOK-mixture of organic acids), which has the following composition, wt.%:
terephthalic acid 80-85 p-toluic acid 8-15 benzoic acid up to 0.4 4-carboxybenzaldehyde up to 0.1 rest water,
moreover, the process is carried out at 250-255 ° C in the fatty acid method with simultaneous loading of the starting reagents with the conclusion of the reaction water by fusion.