WO1999054380A1 - Method for producing polyester alcohols, and polyester alcohols - Google Patents

Abstract

The invention relates to a method for producing polyester alcohols and polyester alcohols produced according to said method, in accordance with the preamble of claim 1. The aim of the invention is to provide a method for producing polyester alcohols with a wide viscosity range by transesterification using waste materials. To this end polyester waste is reacted, at elevated temperatures and in a single reaction step, with a resin containing hydroxyl and ester groups in the presence of the metallo-organic compounds contained therein and possibly glycols and/or aliphatic dicarboxylic acids. The resin containing hydroxyl and ester groups and used according to the invention is a mixture which contains oligohydroxy esters and is an undesirable by-product of polyester condensations and which at present has to be disposed of as waste.

Description

 Process for the production of polyester alcohols and polyester alcohols

description

The invention relates to a process for the production of polyester alcohols and polyester alcohols which are produced by this process, according to the preamble of claim 1.

The depolymerization of polyesters, primarily polyethylene terephthalate (PET), by reaction with alcohols is known. This so-called alcoholysis is generally carried out with monoalcohols or dialcohols such as glycols at elevated temperature, catalysts often being added to the reaction mixture in order to achieve acceptable reaction times. If the reaction is carried out without a catalyst, longer reaction times and / or higher temperatures are generally required. So z. Such a depolymerization process by glycolysis by UR Vaidya, VM Nadkarni, polyester polyols for polyurethanes from PET waste, in J. Appl. Polym. Be. 35: 775-785 (1988). Thereafter, PET fiber waste with different amounts of ethylene glycol is converted to oligomeric diols in the presence of zinc acetate at temperatures between 170 ° C and 200 ° C in about 10 hours. With adipic acid and toluenesulfonic acid, these further become polyesters converted. Ultimately, the excess of ethylene glycol leads to a depolymerization up to the stage of bis (2-hydroxyethyl) terephthalate and its reaction with adipic acid.

The depolymerization of the PET can be accelerated by the reaction under pressure and the addition of typical transesterification catalysts, so that the process can be carried out on a large technical scale. The main goal of these depolymerization processes is the recovery of dimethyl terephthalate, see e.g. B. DE 26 57 044 and US 5051528. Since the PET wastes in the melt of bis- (2-hydroxyethyl) terephthalate or of oligomers or their mixtures dissolve relatively quickly and with prolonged exposure to temperature up to an oligomer melt takes place, this is then condensed back into the polymer. In order to obtain salable products, clean and pretreated waste with a known composition and origin is required for glycolysis.

By reacting with various glycols, starting materials for polyurethanes are obtained, the depolymerization being the fastest in the case of ethylene glycol, while lower reaction rates were found with propylene glycol, diethylene glycol and neopentyl glycol (see: UR Vaidya, VM Nadkarni, polyester polyols from PET waste: effect of glycol type on kinetics of polyesterification in J. Appl. Polym. Sci. 3_8, 1179-1190; 1991). According to UR Vaidya, VM Nadkarni, Unsaturated polyester resins from PET waste: 1. Synthesis and characterization, in Ind. Engng. Chem. Res. 26, 194-198 (1987) obtained by reaction with maleic anhydride, which can be used in polyester resins.

EP 0113507 describes the production of polyester alcohols on two different polyester waste streams. The process relates to a waste stream from dimethyl terephthalate production, which consists of dimethyl terephthalate and the by-products of the substituted benzene, while the second waste stream consists of residues from the production of PET. The first waste stream is reacted with an alkylene glycol and the two streams are then reacted together, so that a polyester polyol is produced therefrom. EP 0154079 describes a process for the production of terephthalate polyols in which PET waste is reacted with glycols and the ethylene glycol formed during the reaction is distilled off. Higher functional alcohols, e.g. B. N-methylglucoside, triethanolamine, diethanolamine or glycerol can be added.

Polyester polyols produced by these processes generally have a viscosity which is too high for machine processing, so that it is desirable to obtain polyester polyols based on terephthalic acid with a lower viscosity and the same good properties. A serious deficiency of the previously known processes and the OH-functional products produced thereafter is therefore their high viscosity, which makes processing in polyurethane systems with conventional technology difficult or even impossible. A disadvantage of all processes is that they only use primary materials for the implementation and can therefore only work economically if high-quality and pure end products are produced.

The object of the invention is to provide a process for the production of polyester alcohols with a wide viscosity range by transesterification using waste materials and polyester alcohols and their use.

According to the invention the object is achieved in that polyester wastes are reacted with a resin containing hydroxyl and ester groups in the presence of the organometallic compounds they contain at elevated temperature in one reaction step. The resin containing hydroxyl and ester groups used according to the invention is an oligohydroxyester-containing mixture which is formed as an undesirable by-product in the case of polyester condensation and which currently has to be disposed of as waste. This mixture containing oligohydroxy esters is generally a highly viscous to solid distillation product from polyester production at room temperature, in which a substantial proportion of organometallic compounds are dissolved as residues of transesterification catalysts. The mixture containing oligohydroxy esters has a different composition due to the production conditions of the polyester and essentially consists of low molecular weight esters of dicarboxylic acids, for PET it is terephthalic acid and glycols, for PET it is ethylene glycol and / or diethylene glycol, from free ethylene glycol, diethylene glycol and de ^¬ ren higher homologues, such of organometallic compounds. B. of titanium, antimony, bismuth, Ger ^¬ manium, magnesium, calcium, lead, zinc, tin or cobalt, and from free terephthalic acid.

A typical composition of a mixture containing oligohydroxy esters, which can be obtained in the production of PET, is e.g. B .:

40-80 mass% terephthalic acid, 5-30 mass% bound ethylene glycol, 1-20 mass% free ethylene glycol, 1-20 mass% bound diethylene glycol, 1-15 mass% free diethylene glycol,

0 - 10% by mass of longer-chain ethylene glycols, 0.5 - 5% by mass of organometallic compounds.

To control the properties of the polyester alcohols prepared according to the invention, further glycols and / or triols or tetrols, di- and / or polycarboxylic acids or their anhydrides can be added to the reaction mixture.

Furthermore, the reaction mixture to control the properties of the reaction product, and thus also the plastics made therefrom, higher-functional alcohols, for. B. glycerol, trimethylolpropane, pentaerythritol and / or hexanetriol, with the aim of producing branched polyester alcohols.

The ratio of the polyester is preferably too

Oligohydroxyesters are between 0.1: 1 and 1: 0.1, the range between 0.5: 1 and 1: 0.5 is particularly preferred. Furthermore, a reaction mixture is preferred in which the ratio of PET to oligohydroxyester is between 0.6: 1 and 1: 0.6 and which also contains between 5 and 50% by mass of a glycol, in particular diethylene glycol, oligoethylene glycol or dipropylene glycol .

Another preferred variant is to mix the PET in a mixture of oligohydroxyester, diglycol and a triol in the ratio PET: oligohydroxyester: glycol: triol = (0.5-1): (0.5-1): (0.5 01 - 0.2): (0.01 - 0.1) to convert to a branched polyester alcohol.

In a further development of the invention, between 5 and 25% by weight of an aliphatic dicarboxylic acid and / or its anhydrides is additionally added to the glycolysis mixture of glycols, oligoesters and / or polyethylene terephthalate during the transesterification reaction.

It has been found that the viscosity of polyols based on polyethylene terephthalate can be significantly reduced by the fact that during the reaction with glycols, the transesterification or glycolysis, apart from glycols and / or oligoesters, a certain one, but distinctly compared to terephthalic acid a smaller molar amount of adipic acid or of another aliphatic dicarboxylic acid or its anhydrides is added. The viscosities found without this addition are in the range of 15,000 to 350,000 Pas (20 ° C) based on literature and based on our own experience. For processing such polyester polyols on foams However, viscosities below 5000 mPas (20 ° C) are required. The viscosity can be reduced to 1,000 mPas (20 ° C) by adding aliphatic dicarboxylic acids in certain proportions, which are calculated on the polyethylene terephthalate.

Advantageous quantitative ratios of polyethylene terephthalate to aliphatic dicarboxylic acid are in particular in the range from 5 to 25% by weight of the latter. This means a molar ratio of terephthalic acid or another aromatic di- or tricarboxylic acid to aliphatic dicarboxylic acid in a ratio between 12.5: 1 and 2.5: 1. In particular, the range between 10: 1 and 4: 1 is found to be advantageous because the viscosity can be easily regulated in it by adding the aliphatic dicarboxylic acid.

The polyester alcohols are prepared in one or more stages. The number of stages is primarily dependent on the type of starting materials and the desired speed of implementation. In the one-step process, either a glycol, a glycol mixture or an oligoester condensate or a mixture of glycols and oligoester condensates is placed in a reaction vessel and heated to a first reaction temperature. At this temperature, which is generally between 150 and 220 ° C, the polyethylene terephthalate in the form of shredded material, chips, granules, ground material or powder is then added and dissolved. After complete dissolution, the temperature is raised to the second reaction temperature, which is generally between 180 and 280 ° C. lies. After the reaction temperature has been increased, the aliphatic dicarboxylic acid is added in several steps, small amounts of water being drawn off via a condenser. Depending on the dicarboxylic acid to be added, two to ten dosing steps are required. A dosage in four stages which lie in the first half of the total reaction time is preferred. The duration of the reaction at the second reaction temperature is between three and twelve hours, with reaction times of four to eight hours being preferred.

The multi-stage process can in turn be a two-stage, three-stage or four-stage method. A higher number of process stages (cascades) is not favorable for economic reasons, but an infinite number of stages are possible for carrying out the process. The multi-stage process is used in particular when a high percentage of polyethylene terephthalate is to be incorporated and / or when this polyethylene terephthalate is contaminated by other plastics or contains them for various reasons. Of these processes, the two-step process is particularly preferred.

The two-stage process can be operated in two basic embodiments. The application of these process variants is primarily dependent on the starting material available. In the two-stage process, polyethylene terephthalate waste is used in particular. These can be used as pure regrind (e.g. from beverage bottles) or as made with other plastics. mixed shredder goods are available. In a first basic embodiment of the process, the glycol mixture or the mixture of glycols and oligoester condensate are placed in a reaction extruder at temperatures between 150 and 200 ° C. and the polyethylene terephthalate waste is metered in by a separate feed. The processing with residence times of 0.5 to 5 minutes and the high shear forces of the extruder screw (s) achieve a homogenization of the reaction mixture. The non-soluble or dispersible plastic parts are separated by means of a screening device when leaving the extruder. The homogeneous mixture is placed in a second reaction vessel and heated to temperatures of 180 to 280 ° C in this. As soon as the reaction temperature is reached, the aliphatic dicarboxylic acid is metered in in several proportions, as has been described for the one-step process.

In a second basic embodiment, the glycol or the mixture of glycols and / or oligoester condensates are placed in a first reaction vessel and heated to a predetermined dissolution temperature between 150 and 250 ° C. and then the polyester, in particular polyethylene terephthalate waste, is added in the desired ratio. The mixture is stirred at reaction temperatures of 150 to 250 ° C until the polyester has completely dissolved. Other polymers can disperse or suspend in the solution. Some of the foreign plastics contained in the polyester waste, especially PVC and styrene polymers, will remain unchanged in the 10

is removed through a sieve and the mixture is pumped into a second reactor for transesterification. In this second reaction vessel, the transesterification is carried out at temperatures between 180 and 280 ° C within 3 to 12 hours. As soon as the reaction temperature is reached, the aliphatic dicarboxylic acid is metered in in several steps, as has been described for the one-step process.

After completion of the transesterification, the polyester alcohols produced according to the invention are filled directly into storage or storage containers without further processing. The essential product data are the hydroxyl number (OHZ) and the viscosity. The OHZ is between 125 and 400, the viscosity between 1200 and 12,000 mPas (20 ° C) depending on the embodiment of the process.

Suitable glycols for the process are ethylene glycol and its oligomers, especially diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols with an average molecular weight of 200, 300, 400, 600, 800, 1000; Propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycols with an average molecular weight of 200, 300, 400, 600, 800, 1000; 1,4-butanediol, polybutylene glycols of average molecular weights between 200 and 1000 and 1,6-hexanediol.

Suitable aliphatic dicarboxylic acids are in particular adipic acid, furthermore malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, fumaric acid, maleic acid, azelaic acid, cyclohexanedicarboxylic acids or the anhydrides of the acids 11

form, e.g. B. succinic anhydride or maleic anhydride.

Oligohydroxyester condensates are an undesirable by-product of polyester condensations and are currently being disposed of as waste. They are generally highly viscous to solid distillation products from polyester production at room temperature, in which a substantial proportion of organometallic compounds are dissolved as residues of transesterification catalysts. Due to the production conditions of the polyesters, the oligoester condensates have a different composition and essentially consist of low molecular weight esters of dicarboxylic acid, for PET of terephthalic acid, with the glycols, for PET, ethylene glycol and / or diethylene glycol, free ethylene glycol, diethylene glycol and their higher homologues, organometallic compounds such. B. of titanium, antimony, bismuth, germanium, magnesium, calcium, lead, zinc, tin or cobalt, and free dicarboxylic acid, in PET terephthalic acid.

The oligohydroxy esters are used for the polyester alcohols, in particular in relation to the polyester between 1: 4 and 4: 1 and the glycol or glycol mixture from 2: 7: 1 to 7: 2.5: 0.5. Since these areas are very large and allow many variants, some typical relationships are described in the examples. However, these are not to be seen as the limits of the possible variations, since these are determined solely by the required properties of the polyester alcohols. 12

The process according to the invention enables linear and branched polyester alcohols with hydroxyl numbers from 150 to 600 and viscosities (at 20 ° C.) from 3000 to 500,000 mPas to be produced, which have an increased aromatic content compared to previous products. This means that they can be used in particular for high-quality and flame-retardant polyurethanes.

Furthermore, the polyester alcohols according to the invention are advantageously used for the production of rigid polyisocyanate foams. In addition, by incorporating unsaturated dicarboxylic acids (maleic acid, fumaric acid) or their anhydrides, unsaturated polyester alcohols can be produced, which can be used advantageously in the production of paints, coatings and adhesives.

A major advantage of the invention is that polyester waste, in particular PET, polybutylene terephthalate, etc., with other waste, in particular the condensation residues from polyester synthesis, from glycerol production (glycerol pitch), from trimethylolpropane production (TMP pitch) or from the polyether synthesis (distilled glycol mixture) can be converted into high-quality raw materials without additional catalysts and, to a greater extent, new glycols having to be used for the synthesis, so that there is an ecological as well as an economic progress. Furthermore, by using the method according to the invention, in particular the polycondensation residues not previously used with the therein 13

contained catalyst residues, which arise in the technical polyester synthesis, made usable and recycled.

The polyols produced by the process according to the invention are notable for high stability during storage and good miscibility with the additives in polyurethane systems. The reason for these desired good properties is the broad molar mass distribution achieved by the production process according to the invention, both of the terephthalate esters themselves and of the alkylene glycol units arranged in them. While the degree of polymerization of PET is in the order of 90 to 100, that of the oligohydroxy esters is 2 to 4. Due to the transesterification, with the participation of the organometallic catalyst residues contained in the oligohydroxy esters, the alkylene glycols present in it result in rapid chain cleavage on the ester groups and thereby causes a reduction in the degree of polymerization. Since these transesterification reactions are equilibrium reactions, the chain splitting takes place according to statistical laws. The oligohydroxy esters do not reach higher degrees of polymerization, but remain in the mixture as comparatively low molecular weight polyester polyols. The degrees of polymerization of PET achieved by the transesterification reach values between 40 and 5, so that a broad molar mass distribution is achieved, which is confirmed by gel permeation chromatography. The combination of a broad molecular weight distribution and incorporation of an alkylene glycol mixture into the polymer chains, thereby replacing the short-chain ethylene glycol with higher homologs, leads to the desired, invented 14

Properties according to the invention which cannot be obtained from the oligohydroxyesters or from the PET by a direct depolymerization by transesterification with only one glycol, since in these cases products of a completely different molar composition and molar mass distribution arise which are still crystallizable and are therefore not stable .

The process according to the invention and the products according to the invention can moreover be produced in a wide viscosity range by different ratios of the starting materials. The viscosity set depends on the intended use. The viscosity for the production of rigid foams should be in the range of 4,000 to 10,000 mPas (20 ° C), while that for coatings and lacquers can be in the range up to 25,000, that for hot melt adhesives up to 100,000. One area of application of great interest is rigid polyurethane and polyisocyanurate foams. For machine technology processing, viscosities of around 3,000 mPas (20 ° C) are required, which cannot be achieved using the previous methods. In contrast, the process according to the invention even allows viscosities below 1000 mPas (20 ° C.) to be set.

The invention is explained in more detail using the following exemplary embodiments.

example 1

In a 6 1 stirred reactor with heating, thermometer, stirrer, column with column head and condenser 15

2.85 kg of oligohydroxyester are added to the sat drain, cooler and inert gas flushing and melted. A clear, highly viscous product is obtained at 65 ° C. The temperature is raised to 150 ° C. At this temperature, 1.85 kg of PET waste (obtained by crushing film waste after the gelatin layer has been removed) is added over the course of two hours. The temperature is slowly increased to 220 ° C and the reaction water is drawn off at the top of the column. The temperature is held at 220 ° C for a further two hours until no more water is produced. The pressure in the reactor is then reduced to 100 mbar in order to remove water residues and volatile components. A crystal-clear, highly viscous liquid with a hydroxyl number of 228 mg KOH / g and a viscosity of 68,000 mPas (20 ° C.) is obtained.

Example 2

The approach of Example 1 is repeated with the following amounts:

2.45 kg oligohydroxyester

2.55 kg of PET waste (from ground beverage bottles).

The reaction is also carried out at 220 ° C., however, this temperature is maintained for 3 hours after the PET addition has ended. The product is a highly viscous syrup with a hydroxyl number of 189 mg KOH / g and a viscosity of 165,000 mPas (20 ° C). 16

Example 3

The approach of Example 1 is repeated with the following amounts:

2.35 kg oligohydroxyester

2.17 kg of PET waste (shredded film waste).

The reaction is also carried out at 220 ° C., however, this temperature is held for 3 hours after the addition of PET has ended and the pressure is then applied at 200 bar. The product is a viscous liquid with a hydroxyl number of 253 mg KOH / g and a viscosity of 22,000 mPas (20 ° C).

Example 4

The approach of Example 3 is repeated with 1.15 kg of diethylene glycol, but otherwise under the same conditions. The product is a viscous liquid with a hydroxyl number of 326 mg KOH / g and a viscosity of 11,600 mPas (20 ° C).

Example 5

The approach of example 3 is carried out in further variants:

Input materials (in kg) A B C D

Oligohydroxyester 2.20 2.20 2.20 2.00

PET waste 2.20 2.50 2.80 3.00

Diethylene glycol 1.00 1.10 1.20 1.00

Viskosität (mPas, 20°C) 14.700 15.900 19.400 36.500 17Hydroxyl number (mg KOH / g) 297 303 289 271

Viscosity (mPas, 20 ° C) 14,700 15,900 19,400 36,500 17

Example 6

The approach of Example 3 is carried out with the following composition:

Oligohydroxyester 1.95 kg

PET waste 2.20 kg

Diethylene glycol 0.95 kg glycerine pitch 0.56 kg

However, the reaction is completed within 3.5 hours at 230 ° C. after the PET addition has ended.

The product has a hydroxyl number of 307 mg KOH / g and a viscosity of 42,000 mPas (20 ° C).

Example 7

The approach of Example 6 is repeated, but 0.44 kg of triethylolpropane (TMP) are used instead of the glycerol pitch. The reaction is otherwise carried out under the same conditions. The product is a highly viscous liquid with a hydroxyl number of 301 mg KOH / g and a viscosity of 38,600 mPas (20 ° C).

Example 8

The approach of Example 7 is repeated with the following amounts:

Oligohydroxyester 2.15 kg

PET waste 1.90 kg

Diethylene glycol 1.20 kg TMP 0.60 kg 18th

However, the reaction is completed within 3.5 hours at 230 ° C. after the PET addition has ended. The product has a hydroxyl number of 341 mg KOH / g and a viscosity of 28,700 mPas (20 ° C).

Example 9

The approach of Example 8 is repeated with the following amounts:

Oligohydroxyester 2.10 kg

PET waste 1.90 kg

Diethylene glycol 1.40 kg TMP 0.30 kg

However, the reaction is completed within 3.5 hours at 230 ° C. after the PET addition has ended.

The product has a hydroxyl number of 385 mg KOH / g and a viscosity of 11,350 mPas (20 ° C).

Example 10

In the apparatus of Example 1, a batch is carried out as follows: 0.58 kg of maleic anhydride and 1.30 kg of diethylene glycol are added to 2.05 kg of melted oligohydroxyester at 80 ° C. and the temperature is raised to 150 ° C. Now 1.75 kg of polyester waste (from shredded films and fibers) are added within 1.5 hours and the temperature is slowly increased to 220 ° C. The reaction is brought to an end within 3 hours while slowly raising the temperature to 228 ° C. While the temperature is slowly rising 19

190 ° C is reduced, the pressure in the reactor is continuously reduced to 125 mbar. Obtained ei ^¬ NEN unsaturated polyester alcohol having the Hy ^¬ droxylzahl 168 mg KOH / g and a viscosity of 68,000 mPas (20 ° C), which is used to adhesives and thereby to free radical polymerization in the presence of Benzoylpero- hydroxide.

Example 11

In a 90 liter reaction vessel, 23.5 kg of oligomeric residues of the polyester condensation (polyether terephthalate production) are melted at about 140 ° C within one hour. 16.5 kg of diethylene glycol are then mixed in with stirring. In this reaction mixture you wear within 15 min. 25 kg of PET waste (fibers, granules or shredded material). The temperature is raised to 190 ° C. in 30 minutes. At this temperature, the batch is stirred for 2-3 hours. The water of reaction formed, released residual water and released ethylene glycol are separated off via a side outlet of the reactor cooler. When the reaction is complete, the mixture is cooled to 120 ° C. and drained off. The resulting product has a hydroxyl number of 347 mg KOH / g and a viscosity of 14,630 mPas (20 ° C).

Example 12

23.5 kg of oligomeric residues of the polyester condensation (polyethylene enterephthalate production) are placed in a 90 l reaction vessel at about 140 ° C. 20th

melted within an hour. Then 22 kg of dipropylene glycol are mixed in with stirring. In this reaction mixture you wear within 15 min. 34 kg of PET waste (fibers, granules or shredded material). The temperature is raised to 220 ° C. in 30 minutes. The mixture is stirred at this temperature for 3 h. After completion of the reaction, the mixture is cooled to 110 ° C. and drained off through a sieve. The resulting product has a hydroxyl number of 362 mg. KOH / g and a viscosity of 9,800 mPas (20 ° C).

Example 13: Repetition of the batch from example 1 with 10% by weight of aliphatic dicarboxylic acid

2.5 kg of oligohydroxyester are introduced into a 6 1 stirred reactor with heating, thermometer, stirrer, column with column head and condensate discharge, cooler and inert gas flushing and melted. A clear, highly viscous product is obtained at 65 ° C. The temperature is raised to 190 ° C. At this temperature, 200 g of adipic acid and, after one hour, 1.8 kg of PET waste (obtained by comminuting film waste after the gelatin layer has been removed) are added over the course of two hours. The temperature is slowly increased to 220 ° C. and water of reaction formed is drawn off at the top of the column. The temperature is held at 220 ° C for a further two hours until no more water is produced. The pressure in the reactor is then reduced to 100 mbar in order to remove water residues and volatile components. A clear, viscous liquid with a hydroxyl number is obtained 21

of 267 mg KOH / g and a viscosity of 6,450 mPas (20 ° C).

Example 14: Approach with aliphatic dicarboxylic acid and glycol

2.2 kg of oligohydroxyester are placed in a 6 1 stirred reactor with heating, thermometer, stirrer, column with column head and condensate discharge, cooler and inert gas flushing and melted. A clear, highly viscous product is obtained at 65 ° C. 320 g of dipropylene glycol and 120 g of adipic acid are added to this. The temperature is raised to 190 ° C. and held at this temperature for one hour. At this temperature, 2.0 kg of PET waste (obtained by crushing beverage bottles) is then added within one hour. The temperature is slowly increased to 220 ° C. and water of reaction formed is drawn off at the top of the column. The temperature is held at 220 ° C for a further two hours until no more water is produced. The pressure in the reactor is then reduced to 100 mbar in order to remove water residues and volatile components. A clear, viscous liquid with a hydroxyl number of 319 mg KOH / g and a viscosity of 4,680 mPas (20 ° C.) is obtained.

Example 15: Approach with aliphatic dicarboxylic acid

In a 90 1 stirred reactor with thermal oil heating,

Propeller stirrer, column with column head and condensate discharge, cooler and inert gas flushing 22

Added 26 kg of oligohydroxyester and melted. A clear, highly viscous product is obtained at 110 ° C. 2.8 kg of dipropylene glycol and 2.9 kg of adipic acid are added to this. The temperature is raised to 190 ° C. and held at this temperature for one hour. At this temperature, 47.5 kg of PET waste (obtained by crushing beverage bottles) are then added within one hour. The temperature is slowly increased to 220 ° C. and water of reaction formed is drawn off at the top of the column. The temperature is held at 220 ° C for a further three hours until no more water is produced. The pressure in the reactor is then reduced to 100 mbar in order to remove water residues and volatile components. 15 ml are distilled off. A clear, viscous liquid with a hydroxyl number of 312 mg KOH / g and a viscosity of 4,920 mPas (20 ° C.) is obtained.

Example 16: Approach with aliphatic dicarboxylic acid

26 kg of oligohydroxyester are added to a 90 liter stirred reactor with thermal oil heater, propeller stirrer, column with column head and condensate discharge, cooler and inert gas flushing and melted. A clear, highly viscous product is obtained at 110 ° C. 3.2 kg of dipropylene glycol and 3.5 kg of maleic acid are added to this while flushing with nitrogen. The temperature is raised to 190 ° C. and held at this temperature for one hour. At this temperature, 47.5 kg of PET waste (obtained by crushing beverage bottles) are then added within one hour. The temperature is slowly increased to 220 ° C and 23

water of reaction formed is withdrawn at the top of the column. The temperature is held at 220 ° C for a further three hours until no more water is produced. The pressure in the reactor is then reduced to 100 mbar in order to remove water residues and volatile components. 12 ml are distilled off. A clear, viscous liquid with a hydroxyl number of 315 mg KOH / g and a viscosity of 5,620 mPas (20 ° C.) is obtained.

Example 17: Preparation of a PET polyol according to the invention

26.7 kg of liquid waste from polyester production with the following composition are placed in a 1201 stainless steel reactor with propeller stirrer, gas inlet and gas outlet, heat exchanger / cooler and two filler necks:

2.7% monoethylene glycol,

7.8% diethylene glycol,

4.9% triethylene glycol, 2.2% tetraethylene glycol, 69.2% dimeric terephthalic acid ethylene condensate, 12.7% trimeric terephthalic acid ethylene condensate, 0.5% Sb and Ge compounds.

This mixture is heated to 180 ° C. 4.75 kg of diethylene glycol, 2.3 kg of polyethylene glycol 200 and 7.8 kg of maleic acid are first added to this mixture with stirring. The temperature is raised to 200 ° C within one hour. Then 73.3 kg of PET waste are added within 30 minutes, which have the following composition: 24

91.2% PET,

4, 7% PVC,

3.3% HDPE, 0.8% PS.

The temperature is raised to 215 ° C during the addition. After the addition has ended, the mixture is stirred at 215-220 ° C. for 3.5 hours. No distillation products are detected in the nitrogen stream. At the end of the reaction time, the pressure is reduced to 100 mbar and volatile constituents are distilled off (23 ml); then it is cooled to 130 ° C. and filled through a filter. The PET polyol has a hydroxyl number of 316 and a viscosity of 4,950 mPas (20 ° C).

Claims

25 patent claims 1. A process for the preparation of polyester alcohols by catalytic reaction of polyesters with compounds containing hydroxyl groups at elevated temperature, characterized in that polyester wastes are reacted with mixtures containing oligohydroxy esters obtained as a by-product in polycondensation reactions. 2. The method according to claim 1, characterized in that that the oligohydroxy ester-containing mixtures are used in untreated form. 3. The method according to claim 1 or 2, characterized in that catalysts and / or glycols are additionally added to the mixture containing oligohydroxy esters. 4. The method according to any one of claims 1 to 3, characterized in that an oligohydroxy ester used in the PET production, metal-organic catalysts containing distillation product is used. 26 5. The method according to any one of claims 1 to 4, characterized in that a distillation product of polyethylene terephthalate which is highly viscous to solid, contains catalyst and contains glycol is added at ambient temperature. 6. The method according to any one of claims 1 and 5, characterized in that esters of terephthalic acid with ethylene glycol and diethylene glycol, from free ethylene glycol, from free diethylene glycol, higher oligoethylene glycols and organometallic compounds are added in different weight ratios. 7. The method according to any one of claims 1 to 6, characterized in that 40-80 mass% terephthalic acid, 5-30 mass% bound ethylene glycol, 1-20 mass% free ethylene glycol, 1-20 mass% bound diethylene glycol, 1-15 mass% free diethylene glycol, 0 - 10% by mass of longer-chain ethylene glycols and 0.5 - 5% by mass of organometallic compounds are added. 8. The method according to any one of claims 1 to 7, characterized in that organometallic compounds based on titanium, antimony, bismuth, germanium, magnesi- 27 um, calcium, lead, zinc, tin and / or cobalt are added. 9. The method according to any one of claims 1 to 8, characterized in that polyester waste contained in a mixture of oligohydroxyester mixture, diols and / or polyols, dicarboxylic acids and / or their anhydrides at a temperature of 150 to 250 ° C within 2 up to 20 hours first under normal pressure and then, if necessary, under reduced pressure. 10. The method according to any one of claims 1 to 9, characterized in that 5 to 65 parts by weight of polyester waste in a mixture of 5 to 65 parts by weight of oligohydroxyester, 5 to 45 parts by weight of diethylene glycol, dipropylene glycol, polyethylene glycol and / or polypropylene glycol and 0 to 30 parts by weight Alcohols such as 1,4-butanediol, glycerol, trimethylolpropane, hexanetriol, pentaerythritol, dipropylene glycol, oligopropylene glycols and / or oligoethylene glycol are reacted. 11. The method according to any one of claims 1 and 10, characterized in that 5 to 40 parts by weight of a carboxylic acid, a dicarboxylic acid or an anhydride are added to the reaction mixture. 28 12. The method according to any one of claims 1 to 11, characterized in that the dicarboxylic acid is phthalic acid, adipic acid or maleic acid. 13. The method according to any one of claims 1 to 12, characterized in that the alcohol component used exclusively or partially glycerol pitch, trimethylolpropane pitch or other distillation residues of polyhydric alcohols. 14. The method according to any one of claims 1 to 13, characterized in that the polyester alcohols are prepared in one or more stages. 15. The method according to any one of claims 1 to 14, characterized in that for the preparation of the polyester alcohols in a two-stage process, the glycol mixture or the mixture of glycols and oligohydroxy esters in a reaction extruder at temperatures between 150 and 200 ° C and the by a separate feed Polyethylene terephthalate wastes are metered in, the insoluble or dispersible plastic components are separated off when leaving the extruder by means of a screening device, the homogeneous mixture is placed in a second reaction vessel and in this at temperatures of 180 29 heated to 280 ° C and the aliphatic dicarboxylic acid is added in several proportions. 16. The method according to any one of claims 1 to 14, characterized in that for the preparation of the polyester alcohols in a two-stage process, the glycol or the mixture of glycols and / or oligohydroxyesters in a first reaction vessel and placed between a predetermined solution temperature 150 and 250 ° C heated, the polyester added in the desired ratio, the mixture at temperatures of 150 to 250 ° C until the polyester completely dissolves, the solids content is removed through a sieve and the mixture is pumped into a second reactor for transesterification is transesterified in this second reaction vessel at temperatures between 180 and 280 ° C within 3 to 12 hours and the aliphatic dicarboxylic acid is metered in at the reaction temperature in several steps. 17. The method according to any one of claims 1 to 16, characterized in that for the preparation of the polyester alcohols in a two-stage process oligohydroxy esters in relation to the polyester between 1: 4 and 4: 1 and the glycol or glycol mixture of 2: 7: 1 to 7 : 2.5: 0.5 can be used. 30th 18. polyester alcohols from terephthalic acid, ^further di and / or polycarboxylic acids, glycols and / or triols, characterized by the preparation, by the process according to claims 1 to 17. 19. Low viscosity polyester alcohols based on polyethylene terephthalate and glycols or glycol mixtures and / or oligoester condensates, which can be prepared from the glycolysis mixture of glycols, oligohydroxyesters and / or polyethylene terephthalate and an aliphatic dicarboxylic acid and / or their anhydrides according to Claims 1 to 17. 20. Polyester alcohols according to claim 19, characterized in that the polyester alcohol contains between 5 and 25% by weight of aliphatic dicarboxylic acid and / or its anhydride and contains it in condensed form. 21. Polyester alcohols according to claim 19 or 20, characterized in that the molar ratio of terephthalic acid or another aromatic di- or tricarboxylic acid to aliphatic dicarboxylic acid is in the ratio between 12.5: 1 and 2.5: 1. 31 22. Polyester alcohols according to one of claims 19 to 21, characterized in that the molar ratio of terephthalic acid or another aromatic di- or tricarboxylic acid to aliphatic dicarboxylic acid is in the ratio between 10: 1 and 4: 1. 23. Polyester alcohols according to one of claims 19 to 22, characterized in that the hydroxyl number is between 125 and 400 and the viscosity is between 1200 and 12,000 mPas (20 ° C). 24. Use of the polyester alcohols according to claims 18 and 19 for the production of polyurethanes, polyurethane polyureas, polyurethane polyisocyanurates, polyisocyanurates or unsaturated polyester resins. 25. Use of the polyester alcohols according to claims 18 and 19 for the production of rigid polyurethane foams, rigid polyisocyanurate foams, polyurethane adhesives or polyester adhesives.