CS227502B1 - Method of preparing polyesterpolyols - Google Patents

Description

The invention relates to a process for the production of polyester polyols suitable for the preparation of polyurethanes from petrochemical by-products after a relatively technically undemanding treatment.

Polyester polyols are generally prepared by reacting dicarboxylic or polycarboxylic acids or ioh 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 pTrans · Plast · Inst ·, London 26. 187 (1958); Mod Plastic 9, 145 (1958); Ind. Eng. Chem. 2, 27 (1963)]. Polyesterification is generally carried out at temperatures of 130 to 20 ° C, generally at atmospheric pressure in the presence of a catalyst, while removing the reaction water with an inert gas or azeotropic distillation with xylene.

Another possible method of 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 of catalyst. Thus, for example, alkyd resins are produced from soybean oil (Mleziva J .: Polyesters, SUTL Praha 1964) ) or polyester polyols for polyurethanes from the distillation residue from the production of terephthalic acid

- 2,227,502 and / or dimethyl terephthalate. copyright certificate · ». · The distillation residue from the production of dimethyl terephthalate and / or terephthalic acid contains metals and ioh compounds added to the preceding stages of the production of dimethyl terephthalate, in particular cobalt, manganese, iron, traces of calcium, magnesium, barium, silicon, or other metals, also coming from corrosion of the equipment. Although they act as catalysts for re-esterification, on the other hand, they are very harmful when applying polyester polyols to polyurethanes by significantly shifting the characteristic times of polyurethane preparation and supporting many side reactions of the -NCO group, e.g., trimerization to polymerization. It is therefore necessary to remove metals from the polyol component.

According to the present invention, the process for the preparation of polyester polyols by esterification and / or transesterification of 10 to 100% by weight of the residues from the production of terephthalic acid and / or its dimethyl ester is also possible in admixture with dicarboxylic acids and / or derivatives thereof by dibasic to polyhydric alcohols and / or alkanolamines. 120 DEG C. to 300 DEG C., optionally in the presence of an esterification and / or transesterification catalyst, is generally carried out in an inert atmosphere such that, prior to esterification and / or transesterification, at least some of the metals such as terephthalic acid and / or dimethyl terephthalate cobalt, manganese, iron, heat, nickel and / or metal compounds ·

The advantage of the process according to the invention is the higher quality of the polyester polyol produced, the possibility of its wider use in the production of polyurethanes, and the fact that it regenerates at least part of the oxidation catalyses necessary for the production of dimethyl terephthalate or terephthalic acid.

227 502

The polyester polyols prepared by the process of the invention are suitable raw materials for polyurethanes, in particular rigid polyurethane foams, but also semi-hard and soft polyurethane foams. By removing the metal, in particular cobalt and manganese, from the residues of dimethyl terephthalate or terephthalic acid, the polyol component produced therefrom can then be catalyzed only by activators of polyurethane chemistry and the desired characteristic times can be achieved without compromising the physico-mechanical properties of the final polyurethane product. In this way, the application area of the polyurethanes is greatly expanded, particularly in the manufacture of large blocks, in applications requiring good flow properties, for the volatility of the foam and the tackiness of the foam.

The removal of metals and metal compounds from the distillation residues from the production of terephthalic acid and / or dimethyl terephthalate is carried out by extraction with an organic reagent, the organic reagent may also be a mixture of organic substances, most preferably phosphoric esters, especially trioctyl phosphate, tributyl phosphate ap. More preferably, the extracting agents are organic or inorganic acids, in particular in the form of aqueous solutions or aqueous-alcoholic solutions, in particular sulfuric acid, phosphoric acid, hydrochloric acid, hydrobromic acid, formic acid, acetic acid, oxalic acid and the like. solutions containing extracted metal compounds are relatively easy to regenerate at least the most valuable components, usually in the form of salts, in particular cobalt, manganese, and possibly molybdenum, which can be utilized cautiously, e.g. in the production of terephthalic acid, respectively. dimethyl terephthalate by oxidation of p-xylene. For the production of polyester polyols, the cobalt, manganese and other metal compounds may be used either by the lacquer residue from the production of dimethyl terephthalate and / or terephthalic acid and / or in admixture with dicarboxylic acids, or derivatives such as dicarboxylic anhydrides alkyl esters of dicarboxylic acids and the like.

From viaomocných alcohols are used najmd ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,2-propanediol, 1,4-butanethiol, 1, O-hexanediol, glyeerol _t trimetylolpropén, neopentyl glycol, pentaerythritol, dipentaerythritol, also amino alcohols such as monoethanolamine, diethanolamine, triethanolamine , monoisopropanolamine, diisopropanolamine etc., thioalcohols ·

In the production process of the present invention, esterification is to be understood as meaning also polyesterification, wherein:

Λ in addition to the ester groups, the polyester polyol may also contain * amido groups - CONH

The esterification and / or transesterification of the residues from the production of terephthalic acid and / or its dimethyl ester with polyhydric alcohols or aminoalcohols is carried out in conjunction with an esterification and / or transesterification catalyst, the esterification catalyst being also understood to be a polyesterification catalyst or a esterification catalyst. however, for many purposes, esterification and / or transesterification of the residues of the present invention can also be carried out with non-catalytics, i.e. without the addition of esterification, polyesterification and transesterification catalysts. As esterification, polyesterification, resp. transesterification catalysts include strong mineral acids such as sulfuric acid, phosphoric acid, organic sulfoacids such as benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, but in particular lead, antimony, germanium, tin, titanium, and manganese, The reaction is carried out at temperatures of 120 to 300 ° C, preferably at 160 to 220 ° C. The removal of low-molecular-side by-products of condensation and / or transesterification such as water, methanol and the like is effected by distillation, usually under reduced pressure. but more preferably by blowing through the gas, generally with an inert gas, most often via a footrest, switching off the filling and the temperature at the top of the maz. 100 ° C to prevent the kidnapping of valuable reaction components such as polyhydric alcohols, especially glycols and the like. 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, both the distillation residue and the polyester polyol can be refined, e.g. by treatment with hydrogen peroxide, chlorine or alkali metal hypochlorite, adsorbents and the like. Further details of the method and disadvantages are apparent from the examples.

Example 1

K 1000 g of distillation residues from dimethyl terephthalate production (acid number 62 mg KOH / g, saponification number 472 mg KOH / g, melting point 60 ° C, cobalt content 0,01% w / w, cobalt content in the form of salts 0,25% w / w · Manganese content in the form of salts 0.031% by weight 1000 g of an aqueous solution of sulfuric acid of 2.5% by weight are added and extraction is carried out for 2 hours at 80 ° C. After phase separation, the content of cobalt salts in the residues is reduced to 0 , 01% by weight and manganese salts to 0.002% by weight

Polyester polyol is prepared in a 4-neck 4-volt flask equipped with a stirrer, regulator, temperature, packed riser tempered to 80 ° C and nitrogen inlet. 1000 g of diethylene glycol, 170 g of pentaerythritol and 0.75 g of lead oxide as a trans esterification or pre-esterification catalyst are added to the treated residues from the production of dimethyl terephthalate. The esterification is carried out at 200 [deg.] C. with stirring (revolutions of 4 s ¹ ) and the constant removal of methanol from the reaction medium by means of nitrogen as inert gas at a rate of 40 dm &^lt; ^{-1 &gt};. During the reaction time of 7 h, distillation of 190 cm @ 3 of distillate (methanol content of 90% by weight) is distilled off. ° C 3.8 Pas ·

Example 2

Extraction of bile metals from 1000 g of distillation residue from the production of diemtyl terephthalate (acid number 56 mg KOH / g, saponification number 460 mg KOH / g, dimethyl terephthalate content

8.2% by weight, melting point 55 ° C, cobalt content

0.001% by weight, cobalt content in the form of compounds 0.28% by weight, manganese content 0.001% by weight, manganese compounds 0.05% by weight) are made at a temperature of 90 ° C for 2 hours with 600 g of distilled water acidified 40 g ootic acid · De-distillation residues after distillation of residual water contain 0.03% by weight of cobalt and 0.0005% by weight of manganese in the form of compounds.

Transestarification of the treated residues is carried out in the absence of esterification or transesterification catalyst, in the presence of 1000 g of diethylene glycol and 200 g of glyOerol at 200 ° C. · The reaction time is 10 h. · The dark-colored polyester polyol obtained has an acid number of 0.6 mg KOH / g. , hydroxyl value 450 mg KOH / g and viscosity 3,2 Pas at 25 ° C,

Example 3

By extracting 1200 g of the distillation residues specified in Example 1 with 600 g of trioctyl phosphate at 85 ° C, the cobalt content is reduced to 0.05% by weight and man-%. gan to 0.005% by weight ·

Polyesterpolyol e is prepared by the process according to Example 1 with transesterified and polyestarified residues from the production of diemtyl terephthalate by reaction with 1200 g

- 7 227 502 diethylene glycol and 200 g of trimethylolpropane in the absence of a transesterified and polyesterified catalyst for 10 h · The product is dark with an acid number of 0,8 mg KOH / g, a hydroxyl number of 445 ®g KOH / g and a viscosity

3.2 Waist at 25 ° C ·

Example 4

The content of cobalt, manganese and their compounds in the manufacture of desttlačných zvyškooh The ^ ntylteref terephthalate is gradually reduced om floor ^f and Example 1 · Transesterlfikácia polyesterifikáoia and 1200 g of residue such treated with 217 of ethylene glycol and 250 g of 1,4-butanediol in the presence of 0, 9 g of lead oxide at 210 ° C for 12 h prepare a dark colored polyester polyol with an acid number of 0.8 mg KOH / g and a hydroxyl number of 5 µ, 2 mg KOH / g ·

Example 5

After extraction! 1000 g of distillation residues from the production of terephthalic acid (acid number 457 vag KOR / g, cobalt content of compounds 0,24% w / w, manganese content 0,005% w / w, vanadium content 0,04% w / w),

500 g of hydrobromic acid at a concentration of 10% by weight at 60 ° C for 1 hour contain 0.01% by weight of cobalt and 0.001% by weight of vanadium. Polyesterlfication of the treated residues with 900 g of diethylene glycol and 180 g of trimethylolpropane in the presence of 0, 6 g of tetrabutyl titanate at 205 ° C are terminated after 13 H. The darker polyester polyol has an acid number of 1.9 mg KOH / g, a hydroxyl number of 425 mg KOH / g and a viscosity of 2.4 Pas at 25 ° C.

Claims (2)

OF THE INVENTION 227 502 Process for producing polyester polyols by esterification and / or transesterification of 10 to 100 wt. the residues from the production of terephthalic acid and / or its dimethyl ester also in admixture with dicarboxylic acids and / or derivatives thereof by treatment of dibasic to polyhydric alcohols and / or alkanolamines at a temperature of 120 to 300 ° C, optionally in the presence of an esterification and / or transesterification catalyst, as a rule in an inert atmosphere, characterized in that before esterification and / or transesterification, metals such as cobalt, manganese, iron, chromium, nickel and / or metal compounds are removed at least partially from the distillation residues from the production of terephthalic acid and / or dimethyl terephthalate. . Process according to claim 1, characterized in that metals and / or metal compounds are removed from the distillation residues by extraction with an organic reagent and / or acid, preferably an aqueous acid solution.