CS229429B1 - Method for the producing of polyesterpolyoles - Google Patents

Description

The invention relates to a method for producing polyester polyols from minor petrochemical raw materials.

Polyester polyols are generally prepared by reacting dicarboxylic or polycarboxylic acids or their anhydrides with divalent or polyhydric alcohols, the amount of which depends on the type of raw materials used and the desired properties of the final polyester polyol (Trans, Plast. Inst., London 26. 187 (1958); Mod. Plast. 35, 9, 145 (1958);

Eng. Chem. 2, 27 (1963). Polyesterification is generally carried out at temperatures of 130 to 240 ° C, typically under atmospheric pressure in the presence of a catalyst, while removing the reaction water with an inert gas or azeotropic distillation with xylene.

The disadvantage is the technically demanding and raw material limited production of the starting carboxyl compounds. Another possible preparation is the re-esterification of dicarboxylic acid esters with polyhydric alcohols at temperatures of 180 to 240 ° C in the presence of 0.005 to 0.1% by weight. catalyst. Thus, e.g. soybean alkyd resins (Mleziva J .: Polyesters, SNTL Praha 1964), or polyester polyols from the distillation residue from the manufacture of terephthalic acid or its dimethyl ester (Czech Patent Certificate No. 218 170).

However, even this significant process does not exhaust the possibilities of technical and higher economic recovery of by-products from petrochemical production of oxygen-containing organic compounds.

According to the present invention, the process for producing polyester polyols by esterification and / or transesterification in the presence of acids and esters with substances containing from 2 to 4 hydroxyl groups is carried out in such a way that by-products and / or distillation residues from cyclohexanone β / or cyclohexanol production are oxidized, preferably after pre-purification, they are esterified and / or transesterified with substances containing 2 to 4 hydroxyl groups in an amount of 80 to 180%, calculated on the acid value of the raw materials entering the reaction reduced by the hydroxyl number of the by-products from cyclohexanone and / or cyclohexanol production; to the sum of the acid and saponification numbers of the feedstocks reduced by the hydroxyl number of the by-products from the production of cyclohexanone and / or cyclohexanol.

The calculation of the amount of 2 to 4 hydroxyl groups depends on the procedure used, whether esterification and / or transesterification is used. The saponification number of the by-products from the production of cyclohexanone and / or cyclohexanol is then taken into account in the transesterification.

An advantage of the process for the production of polyester polyols according to the invention is the high technical and economic value of the by-products, generally isolated as a distillation residue from the production of cyclohexanone or cyclohexanol by oxidation of cyclohexane, thereby expanding the raw material base for the production of polyester polyols. A further advantage is that the use of the method according to the invention in connection with the production of cyclohexanone will render the process of producing cyclohexanone virtually waste-free.

By-products with a boiling point generally above the boiling point of cyclohexanol and cyclohexanone, which are generally isolated as a distillation residue from the oxidation of cyclohexane, either alone or in admixture with other oxygen by-products, or dicarboxylic or polycarboxylic acids, or their anhydrides or lactones.

Among the polyhydric alcohols, in particular, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,2-propanediol-1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, amino amino amines, such as monoethanolamine, triethylamine, monoethanolamine are used. , diisopropanolamine and the like, thioalcohols. . ;

Polyesterification and / or transetherification of cyclohexanone and / or cyclohexanol residues by oxidation of cyclohexane is carried out with polyhydric alcohols or aminoalcohols, generally with the aid of a polyesterification and / or transesterification catalyst.

However, for several purposes, the preparation of polyester polyols can be carried out without separately adding polyesterification or transesterification catalysts. In addition, metals and their compounds present in the distillation residue from the previous stages of production, in particular cobalt, possibly other metals, especially transition metals, usually present in low to trace amounts such as manganese, titanium, zinc and others may perform this function.

In some cases, it is expedient to modify the catalyst system by adding other known catalysts having specific effects. If the subsequent application requires that the prepared polyester polyols do not contain any of the metals present in the residues or by-products of the cyclohexanone production, respectively. cyclohexanol by oxidation of cyclohexane, these must be removed beforehand and the polyesterification or transesterification carried out non-catalytically or in the presence of suitable catalysts.

As polyester or resp. transesterification catalysts include strong mineral acids such as sulfuric acid, phosphoric acid, and organic sulfoacids such as benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, but in particular lead, antimony, germanium, tin, titanium, molybdenum, titanium, molybdenum and titanium compounds. . The reaction is carried out by distilling off the water and / or alcohols released by esterification and re-esterification under atmospheric or reduced pressure, by co-treating the usually blown gas, generally inert gas, through a drop catcher, most often through a riser filled with charge to prevent unwanted abduction of valuable reaction components. , such as polyhydric alcohols, in particular glycols and p. The process for producing the polyester polyol according to the invention can be carried out mainly discontinuously, the reaction time being usually 6 to 20 hours, but it can also be carried out semi-continuously and continuously.

In addition, by-products, generally isolated as distillation residues, can be pre-purified, e.g. By the action of hydrogen peroxide, chlorine, resp. alkali metal hypochlorite, adsorbents by hydrotreating or by removing colored impurities by distillation, preferably by film distillation. Many of these processes can also be applied to the final product - polyester polyol. Further details of the preparation process as well as other advantages thereof are apparent from the examples.

Example 1

Polyester polyol is prepared in a 4-neck 4-liter flask equipped with a stirrer, a temperature controller, a step with a temperature of 105 ° C and a inert gas inlet.

To 1000 g of distillation residues from cyclohexanone oxidation (water content 6,4% w / w, acid value 269,2 mg KOH / g, saponification number 416,2 mg KOH / g, hydroxyl value 162 mg KOH / g, bromine number 20 9 g Br / 100 g) was added 850 g of diethylene glycol and 140 g of pentaerythritol ester interchange, and polyesterification is carried out with stirring (speed of rotation 4 with ¹⁾ at 200 DEG C. with continuous removal of low molecular weight products of the reaction from the reaction medium by a stream of inert gas. The reaction yielded 150 coP of distillate (water content 92% by weight, methanol content 6.3% by weight) reaction time is 5.5 h. A dark-colored polyester polyol having an acid number of 1.5 mg KOH / g, a hydroxyl number of 522.1 mg KOH / g and a viscosity of 1.27 Pas at 25 ° C is obtained.

Procedure for calculating raw material consumption

Theoretical alcohol consumption:

Acid number - hydroxyl number of the by-product of cyclohexanone production by cyclohexane oxidation in feed 1000 g = (269.2 mg KOH / g - 162 mg KOH / g) x 1000 g = 107 200 mg KOH. Polyester polyol (having a hydroxyl value of 522.1 mg / g) in an amount of 1.845 g can be expressed as 522.1 mg / g. 1845 g = 963 274.5 mg KOH. Theoretical consumption of alcohols for the preparation of 1,845 g of polyester polyol having a hydroxyl number of 522.1 mg / g = (522.1 mg / g x 1845 g) + + 107,200 mg KOH = 1,070,474.5 mg KOH.

Actual alcoholic beverage:

Amount of alcohols used, expressed in mg KOH:

diethylene glycol = 1,057.4 mg KOH / g x 850 g = 898,790 mg KOH pentaerythritol = 1,648.4 mg KOH / g x 140 g = 230,776 mg KOH c e 1 k o 1 129 566 mg KOH

The actual batch of alcohols is 105.5% of theory.

In the case of changed reaction conditions, for example using reesterification catalysts, the esters present are largely re-esterified, and then a calculation is taken into account taking into account the amount of 2 to 4 hydroxyl groups calculated on the total acidity and saponification value to a reaction reduced by the hydroxyl value (all in mg KOH / g) of the by-products obtained from the oxidation of cyclohexane to cyclohexanone and / or cyclohexanol.

Example 2

Metallic compounds, in particular cobalt, from 1000 g of the distillation residue from the production of cyclohexanone and cycloheanol by oxidation of cyclohexene (acid number 255 mg KOH / g, hydroxyl number 138 mg KOH / g, saponification number 432 mg KOH / g, cobalt content 0.05% % by centrifugation by extraction with 500 g of a 2.3 wt.% aqueous sulfuric acid solution. at 50 ° C for 2 h. After phase separation, the organic layer is neutralized with aqueous ammonium hydroxide solution.

Polyesterfication β pre-esterification of the distillation residues so treated using 800 g of diethylene glycol and 150 g of trimethylolpropane is carried out in the presence of 0.2% tetrabutyl titanate at 205 ° C. The reaction time is 9 h. The obtained dark-colored polyester polyol has an acid number of 0.8 mg KOH / g, a hydroxyl number of 452 mg KOH / g and a viscosity of 1.2 Pas at 25 ° C.

Example 3

By-products from the production of cyclohexanone by oxidation of cyclohexane specified in Example 1 are hydrogenated in a rotating autoclave of 5 turf in the presence of 5% by weight, copper-chromium-calcium (Adkins catalyst) catalyst at 180 ° C and 18 MPa. The bromine number of the product after hydrogenation was reduced by 20.9 to 1.2 g Br / 100 g. After removal of the catalyst, the product obtained is refined by film distillation to obtain 80% by weight of the product. product from natural residues but free from colored impurities and metal salts.

125 g of monoethylene glycol and 0.8 g of tetrabutyl titanate are used as catalysts to polyesterify 1000 g of the distillation residue from cyclohexane oxidation thus treated. The reaction time of the polyesterification is 12 h. The polyester polyester is light in color, has an acid number of 0.6 mg KOH / g and a hydroxyl number of 55.6 mg KOH / g.

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Example 4

80 g of 1,4-butanediol, 65 g of monoethylene glycol and 0.5 g of tetrabutyl titanate as esterification catalyst are used for the polyesterification and re-esterification of 1000 g of distillation residues from cyclohexane oxidation specified in Example 1.

Polyesterification reaction time at 220 ° C with a nitrogen flow rate of 50 dm ^ h ^- 'is 2 hours. The dark polyesterpolyol has an acid number of 2.1 mg KOH / g, a hydroxyl number of 55.2 mg KOH / g and a viscosity at 25 ° C of 7.4 Pas.

Example 5

The residues from the production of cyclohexanone by oxidation of cyclohexane specified in Example 1 are subjected to hydrogenation refining on a nickel catalyst at a temperature of 200 ° C and a pressure of 15 MPa. After refining hydrogenation, the oxidation and hydrogenation catalyst residues are removed by vigorous stirring with half the amount of 5% by weight aqueous sulfuric acid solution. After separation of the aqueous phase, the organic layer is neutralized with ammonium hydroxide and used to prepare the polyester polyol.

For the preparation of the polyester polyol, 1000 g of distillation residues thus treated, 200 g of diethylene glycol and 10 g of trimethylolpropane were used. Using 0.7 g of tetrabutyl titanate and 2.2 g of trietvlamine as a catalyst for the esterification and polyesterification, the reaction time is 9 h. The polyester polyol has an acid number of 0.9 mg KOH / g, a hydroxyl number of 58.5 mg KOH / g and a viscosity of 2.9 Pas at 25 ° C.

Claims (2)

OBJECT OF THE INVENTION 1. Process for the preparation of polyester polyols by esterification and / or transesterification from the presence of acids and esters with substances containing from 2 to 4 hydroxyl groups, characterized in that by-products and / or distillation residues from the production of cyclohexanone and / or cyclohexanol are oxidized with cyclohexane, preferably after pre-purification, they are esterified and / or transesterified with substances containing 2 to 4 hydroxyl groups in an amount of 80 to 180%, calculated on the acid value of the raw materials entering the reaction reduced by the hydroxyl number of the by-products from cyclohexanone and / or cyclohexanol production; the sum of the acid and saponification numbers of the feedstocks reduced by the hydroxyl value of the by-products of the manufacture of cyclohexanone and / or cyclohexanol. Method according to claim 1, characterized in that the pre-purification is carried out by reducing the bromine number and / or by reducing the content of metal compounds and / or by removing color impurities by distillation, preferably by film distillation.