CS244568B1 - Process for producing polyester polyols - Google Patents

Abstract

The subject of the invention is the production of polyester polyols, particularly suitable for the production of poly-. of urethanes, by esterification and/or preesterification. distillation residues from the production of cyclohexanone and/or cyclohexanol by oxidation of cyclohexane, usually contaminated with organic colored compounds and metal compounds and with their subsequent pre-esterification with diols to polyols. The process is carried out in two stages, whereby in the first stage distillation residues from the production of cyclohexanol and/or cyclohexanone are partially or completely esterified and/or transesterified with at least one aliphatic alcohol Ci to C4, while the formed at least partially esterified products are separated by distillation and in the second stage they are transesterified with at least one diol and/or one polyol. In addition to polyurethane chemistry, the prepared polyester polyols can also be used as polymer plasticizers.

Description

244568 3 4

BACKGROUND OF THE INVENTION The present invention relates to the production of high-quality polyol polyols, particularly suitable for the production of polyurethanes, by using secondary oxygenated organic products from a petrochemical process.

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 nature of the materials used and the desired properties of the resulting product. The dicarboxylic or polycarboxylic acids used are: oxalic, malonic, succinic, glucan, adipic, pimelic, corkic, azelaic, sebacic, maleic, fumaric, glucosonic, alpha-hydroxymuconic, alpha- butyl-a-ethylglutaric, alpha-beta-diethylsuccinate, isophthalic, terephthalic, trimellitic, pyrometil, trimezinic and 1,4-cyclohexanedicarboxylic acid. In technical practice, high purity adipic acid is most commonly used (Trans.Plast. Inst., London 26, 187, 1958; Mod. Plast. 35, 9, 145, 1958; Ind. Eng, Chem. 2, 27, 1963; BIOS Final Report No 1498; DombrovE., Polyurethanes SNTL, Prague, 1961, p.32).

Despite the obvious advantages of such pure starting dicarboxylic or polycarboxylic acids, it is disadvantageous only for a number of applications, the considerable technical and energy demands of their production, and the limited sources of pure raw materials for their production and the need for technically demanding equipment. This limits the application possibilities of polyester polyols for the manufacture of mass use products. Alcohols include polyvalent aliphatic and aromatic alcohols, especially ethylene glycol, diethylene glycol, propylene glycol, di-propylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, trimethylene glycol, 1,4-tetramethylene glycol, 1,2-butylene glycol, 1,4 - butanediol, 1,3-pentanediol, 1,6-hexanediol, 1,7-heptanediol, glycerol, 1,1,1-trimethylolpropane, 1,1,1-trimethylolethenopentylglycol, 1,2,6-hexanetriol, dibromonopentyl glycol, 1,10-decanediol, pentaerythritol, 2,2-bis-4-hydroxycyclohexylpropane and others (BIOS Final ReportNo 1498, No 1165; Brit. Pat. 882 603; Brit.pat. 927 175).

Synthesis, respectively. the production of polyester polyols is usually carried out at temperatures of 130 to 240 ° C at atmospheric pressure or near atmospheric pressure, typically the presence of catalysts and the removal of the reaction water by inert gas, or azeotropic distillation with xylene. The particular process for preparing polyester polyols by re-esterification of dicarboxylic acid esters is not practiced because it requires a further step of preparing dicarboxylic acid esters, which is technically and economically more expensive. Such a process is usually used only for the production of polyesters by the re-esterification of natural oils, e.g. soybean oil with polyhydric alcohols in the production of alkyd resins for the paint lacquer industry or in the production of polyethylene terephthalate. C in the presence of 0.005% to 0.1% wt. catalyst (Mleziva J .: Polyesters, SNTL Prague, 1964). An important utilization of low-yield petrochemical raw materials is the preparation of polyester polyols from distillation residues from the production of cyclohexanone and cyclohexanol by oxidation of cyclohexane according to Certificate No. 229 429. However, the distillation residues are dark and contain a relatively large number of metal compounds, especially used as oxidation catalysts for the oxidation of cyclohexane. The polyester polyols obtained can therefore be used mainly in application areas where the color is not dark. However, the disadvantage of the produced polyol polyols is the high metal content, respectively. their compounds, which cause difficulties in the preparation of polyurethanes by a prepolymer process. An important benefit of the pre-application of distillation residues from the production of cyclohexanone and / or cyclohexanol is the further preparation of polyesters with the removal of color impurities and metals according to U.S. Pat. The obtained product is light-colored, free of metal compounds, but is unsuitable for application to polyurethanes by its structure and by lack of hydroxyl groups. The advantages of the known processes make use of the technical problems of the present invention.

According to the present invention, there is provided a process for the preparation of polyester polyols, particularly suitable for the preparation of polyurethanes, by esterification and / or pre-esterification of the distillation residues from the cyclohexanone product and / or cyclohexanol oxidation of cyclohexane, usually contaminated with color compounds and metal compounds and subsequently esterified with diols to polyols. in the presence of an esterification and / or pre-esterification catalyst and optionally by means of other substances, it takes place in two stages, wherein in the first stage at least one aliphatic alcohol C1 to C4 is partially or completely esterifying the distillation residues from the production of cyclohexanol and / or cyclohexanone by oxidation of cyclohexane, the at least partially esterified products being formed by distillation, preferably under reduced pressure, and / or evaporation under reduced pressure from the thin layers, optionally refining and in the other stupnisa preest they erify and / or polyesterifix at least one diol and / or at least one polyol. An advantage of the process for the production of polyester polyols according to the invention is the higher technical and economic recovery of the distillation residue from the production of cyclohexanone and / or cyclohexanol by catalytic oxidation of the cyclohexanone. The main advantage is the fact that the core product is light, does not contain metal compounds, which is particularly advantageous in those cases where the presence of metals for application in polyurethane or coating materials is undesirable. In the preparation of polyester polyols, either the lower alcohol esters prepared by the esterification of the distillation residues from the production of cyclohexanol and the cyclohexanone by oxidation of the cyclohexane with lower C1 to C1 alcohols and subsequent removal of color impurities and metal soaps can be used. It may also be a mixture of these lower alcohol esters with other ester or polyester and polyester polyols, or mixtures of known, mainly aliphatic dicarboxylic or polycarboxylic acids or their anhydrides and / or lactones in the amounts required to achieve the desired properties product.

The proposed process for the production of polyester polyols can be accelerated by known esterification catalysts, pre-esterifications, respectively. transesterification and polyesterification in amounts necessary to achieve a technically and economically advantageous rate of reactants without undesired side reactions. In some cases, esters of lower alcohols are preferred to, or after, removal of metal compounds and color impurities, e.g. refining hydrogenation to remove unsaturated compounds. The hydrogenation hydrogenation is carried out under the catalytic effect of hydrogenation catalysts, in particular on the base of Pt, Pd, Ni, Cu, Cr, Zn (usually in the form of metal or oxide on supports), which mainly catalyze the hydrogenation of the double bonds.

The polyester polyols of the present invention can be produced without the use of, or the presence of, auxiliaries, including solvents, usually aliphatic or aromatic hydrocarbons, then polyester polyol stabilizers, especially prior to oxidation (although esterification, transesterification and polyesterification are effected by vehicles in an inert atmosphere, to which non-staining antioxidants, phosphorous acid, hypophosphites, and the like are present. The weight or molar proportions of the individual components may vary depending on their quality and the desired properties of the final product. Further details of the method of the invention as well as other advantages are apparent from the examples. Example 1

1000 g of methanol and 1300 g of distillation residues from the production of cyclohexanone and cyclohexanol by cyclohexane oxidation with this characteristic are weighed in a 5 dm 3 rotary autoclave: saponification number = 416.2 mg KOH / g; hydroxyl number 188.1 mg KOH / g; bromine number = 20.9 g Bn / 100 g; density at 20 ° C = 37 1137 kg. m-3.

The autoclave is heated to a reaction temperature of 220 ° C and reacted at a pressure of 5.7 MPa for 2 hours. Upon completion of the esterification by atmospheric distillation, the reaction water and unreacted methanol are removed by distillation of 610 g of the fraction containing predominantly methyl esters and dimethyl esters of carboxylic acids, i.e. esters formed from methanol and distillation residues from cyclohexanone production, under reduced pressure. and cyclohexanol by oxidation of cyclohexane.

1000 g of said methanol esters prepared by the above process from the production of cyclohexanone and cyclohexanol by cyclohexane oxidation, with a wash-out number of 405 mg / g, a hydroxyl number of 150 mg KOH / are then weighed into a 2-gallon flask. g, acidity number 1.2 mg KOH / g and dynamic viscosity 2.1 mPa. s, 650 g of diethylene glycol and 80 g of pentaerythritol are added. The reaction is carried out with a catalytic effect of tetrabutyl butitanate in an amount of 0.3% by weight. at 200 ° C, for 8 h, a pale polyester polyol product having a hydroxyl number of 420 mg KOH / g, an acid number of 0.95 KOH / g, a saponification number of 303 mgKOH / g and a dynamic viscosity of 174.9 mPa is obtained. at 25 ° C. Example 2

1000 g of esters prepared from lower alcohols and distillation residues from cyclohexanone and cyclohexanol oxidation of cyclohexane were weighed into a 2 dm 3 flask as described in Example 1. To this were added 55 g of monoethylene glycol, 60 g of 1.4. -butanediol and 1.1 g of tetrabutyl titanate catalyst. The reaction was run in a flask equipped with a column filled with Raschig rings and condenser at 210 ° C for 10 h. Prepare a bright polyester polyol having an acid value of 0.6 milligrams KOH / g, a hydroxyl number of 56.2 milligrams. KOH / g and a dynamic viscosity of 2.1Pa. s at 25 ° C. Example 3

1000 g of lower alcohol esters specified and prepared according to the procedure of Example 1 are weighed into a 2 dm 3 flask. Then 125 g of diethylene glycol, 8 g of trimethylolpropane and 1.2 g of tetrabutyl titanate are added and re-esterified under the conditions of Example 2. The polyesterpolyol product prepared had an acid value of 0.8 mg KOH / g, a hydroxyl number of 55.3 mgKOH / g viscosity 2.6 Pa. s at 25 ° C. acid value = 269.2 mg KOH / g; EXAMPLE 4 1000 g of the fraction containing the predominant methyl esters and dimethyl esters of carboxylic acids prepared according to Example 1 were quenched by hydrogenation in a 5 dmc autoclave in the presence of 5 wt. Raney nickel, at 100 SC and 1 MPa hydrogen for 2 hours. The bromine number of the product after refining drops from 15.8 milligrams. Br / 100 g to 1.6 mg Br / 100 g.

1000 g of refined lower alcohol esters are then weighed into a 2 dm 3 flask, 125 g of diethylene glycol, 8 g of trimethylolpropane, 1.2 g of tetrabutyl zirconate and 1.2 g of sodium hypophosphite are added. The reaction takes place at 210 DEG C., for 18 hours. The polyester polyol obtained is very light colored, has an acid number of 0.6 mg KOH / g and a hydroxyl number of 52.8 mg KOH / g. Example 5

Following the procedure described in Example 1, by reacting 1440 g of ethanol and 1300 g of distillation residue from the production of cyclohexanone by oxidation of cyclohexane, followed by distillation, 550 g of a fraction containing predominantly ethyl esters and dimethyl esters of carboxylic acids are recovered.

1050 g of the obtained fraction are then weighed into a 2 din3 flask, 125 g of diethylene glycol, 8 g of trimethylolpropane and 1 ml of 50% sodium hydroxide solution are added. Reaction at 200 DEG C. for 23 hours yields a polyester polyol having an acid number of 1.5 mg KOH / g and a hydroxyl number of 56.4 mg KOH / g. Example 6

1500 g of isopropyl alcohol and 1000 g of distillation residues from the production of cyclohexanone and cyclohexanol by oxidation of cyclohexane with the characteristics described in Example 1 were weighed into a 5 dm 3 rotary autoclave. The autoclave was heated to a reaction temperature of 220 ° C and 4.5 MPa re. -agulates the mixture for 4.5 hours. After the esterification is complete, the reaction water and unreacted isopropyl alcohol are removed by distillation at atmospheric pressure. Then 680 g of the fraction containing predominantly isopropyl esters and diisopropyl esters of carboxylic acids present in the distillation residues from the preparation of cyclohexanone and cyclohexanol by the oxidation of cyclohexane are distilled off under reduced pressure.

Thereafter, 1000 g of the obtained acid fraction of 12.4 mg, / g, the hydroxyl number of 171 mg KOH / g, the saponification number 380 mgKOH / g are added to the flask of 2 dm @ 3, 140 g of diethylene glycol, 1 14 g of GTB is re-esterified and re-esterified at 220 DEG C. for 20 h. A polyester-polyol product of 4.2 mg KOH / g, saponification number of472 mg KOH / g and hydroxyl number of 48 mgKOH / g is obtained. Example 7

300 g of n-butanol, 1000 g of distillation residue from cyclohexanone and cyclohexanol by oxidation of cyclohexane, 7.8 g of p-toluenesulphonic acid were weighed into a 3 l sulphonation flask equipped with an esterification tube. The esterification takes place at the boiling point of the mixture, usually at 110 to 200 ° C, at atmospheric pressure. After the esterification is complete, unreacted butanol is removed by distillation under atmospheric pressure to give the product with an acid value of? = 2.6 mg KOH / g, OH = 14.8 mg KOH and saponification = 376 mg KOH / g. Then, 600 g of the fraction containing predominantly butyl esters or dibutyl esters of carboxylic acids present in the cyclohexanone and cyclohexanol distillation residues of cyclohexanol are distilled off under reduced pressure. 1000 g of the obtained fraction with an acid value of 25.6 mg KOH / g and saponification, a hydroxyl number of 82 mg KOH / g, a saponification number of 385.4 mg KOH / g were weighed into a 2 dm3 flask, 110 g of ethylene glycol, 1 was added, 2 g of tert-butyl titanate and the mixture is esterified and re-esterified at 210 ° C for 16 hours. The polyester polyol was obtained with an acid number of 1.8 mg KOH / g, a saponification number of 480 mg KOH / g and a hydroxyl number of 53 mg KOH / g.

Claims (1)

SUBJECT Process for producing polyester polyols, particularly suitable for the production of polyurethanes, by esterification and / or transesterification of distillation residues from the production of cyclohexanone and / or cyclohexanol by oxidation of cyclohexane, usually contaminated with colored compounds and metal compounds, followed by their esterification with diols to polyols in the presence of esterification and / or a transesterification catalyst and, where appropriate, excipients, characterized in that it is carried out in two stages, BACKGROUND OF THE INVENTION, the distillation residues from the production of cyclohexanol and / or cyclohexanone are partially or completely esterified by the at least one aliphatic alcohol C1 to C8, by oxidation of cyclohexane, the at least partially esterified products formed being distilled off, preferably under reduced pressure and / or evaporated under reduced pressure. of thin layers, if necessary, are more refined, and in the second stage they are re-esterified and / or polyesterified by at least one diol and / or at least one polyol.