SU667148A3 - Method of producing poly(terephthalate)ethylene - Google Patents

Description

one

The invention relates to the production of polyethylene terephthalate, used for the production of fibers, films and other molded products.

A method of producing polyethylene terephthalate is known by esterifying terephthalic acid with ethylene glycol and polycondensation. The esterification is carried out in the melt, and the polycondensation in the solid phase ii.

However, when implementing this method, it is necessary to harden the reaction melt before polycodensation and grind it into particles of the required size.

The purpose of the invention is to simplify the process.

This object is achieved in that in the method for producing polyethylene terephthalate by esterification of terephthalic acid with ethylene glycol and polikondeisatsii esterification and polycondensation is carried out simultaneously in the solid phase, the ethylene vapors fed into the reaction mixture until the sootnoshakn between reacted and unreacted glycol tereftoshevoy acid 0.97: 1 respectively .

The advantage of the process according to the invention is that the reaction of the interaction of terephthalic acid with ethylene glycol and polycondensation takes place at the same time within the packed layer, so that o) one of a large amount of melting and unreacted terephthalic acid - both are present in the intermediate stage of the process, and oligomer species with a lower melting point are present in a smaller amount.

The presence of a catalyst for the formation of ester will react to

positive results. Such a catalyst can be introduced in. Solid

0 terephthalic acid before it reacts. If the catalyst is volatile, then it can be introduced into the reaction mixture or it can be maintained at the required level of its concentration.

Claims (1)

5 by evaporation in a stream of inert gas, which is then passed while being in contact with terephthalic acid. Preferred catalysts for the formation of ester are those which are typically used to accelerate polycondensation reactions in the preparation of polyesters, for example, surium, germanium, tin and titanium compounds. It is important to have a Balancing Behavior ykhkadu reaction of ester formations due to ethylene glycol and a polycondensation reaction so that the concentration of oligomeric varieties with a low melting point would remain small. The temperature at which Teikoe balancing can be achieved depends on the structure of the polymer, the vapor feed rate and the concentration of the catalyst; nevertheless, these temperatures are usually within 160-240 ° C. In the case of a separate, independent, step-by-step process to produce a powdered product, the temperature during this final operation can be raised if the melting point of the product is high enough. It follows that the process corresponding to the invention under consideration may be carried out in such a way as to increase the reaction temperature as the degree of conversion leading to increases. polymer formation. In this case, the temperature in the last stage may exceed 240 ° C. If ethylene glycol is supplied to the packed layer for an excessively long period of time, the packed layer melts due to the reaction of ethylene glycol with high melting types of polymeric materials that are already available. & as a result of this reaction, high-melting varieties turn down melting oligomeric varieties having a hydroxyl / adrenaline ripynntil For this reason, it is important to stop feeding ethylene glycol to the packed layer before excessive amounts of such varieties having a low melting point are formed. ; It is permissible and practical to vary the feed rate of ethylene glycol as the reaction proceeds, in particular to reduce the feed rate as the increase in concentration between the reacted glycol units and the total number of units of terephthalic acid and staining ether in the packed layer. If cKOjpbcTb of ethylene glyco 1H supply to the upper layer is too small, then the total time spent for the reaction becomes excessively large. On the other hand, if the feed rate is unnecessarily high, then the balance between the reaction of forming nbgb of ether due to ethylene glycol and the polycondensation reaction is shifted along the directions of the terephthalic acid derivatives to be 0.97: 1. Powder polymerization of the residual low molecular weight polyethylene terephthalate at a temperature in the atmosphere to the first of these reactions so that low melting oligomeric species are formed in excessive concentration and melting takes place. The higher the melting point of the resulting polyester, the higher the feed rate can be tolerated without fear of melting. When preparing polyesters for the process in question, it is applicable, after stopping the supply of ethylene glycol, to continue the polymerization of the solid product as individual particles in order to obtain a higher molecular weight. Hot product after stopping such filing. A mixture of high melting polymer varieties and kis; 7, including non-reactive source material, with further chemical treatment, leveling occurs, resulting in a solid product containing high melting polymer varieties. It is feasible and practical to resume resuming the supply of ethylene glycol for a short period during or after the said alignment, meaning that the ratio between the Number of units of reacted glycol to the total number of units of terephthalic acid and ester in the packed layer does not increase than 637-1. The process may be carried out on a periodic basis. It is permissible to carry out the process continuously, for example, by continuously feeding terephthalic acid into the first stage of a multistage reactor. In the examples below, in accordance with the invention, all parts are by weight. Example 1. 65 parts of terephthalic acid in the form of particles having an average size of about 100 microns are mixed with 0.13 parts of tetraisopropyl titanate and heated in a reactor operating on the pseudo-fluidized bed principle at a temperature in a stream of nitrogen (7.5 parts per minute). Ethylene glycol vapors (5.07 parts were shnutyu) served in a stream of nitrogen for 20 hours. Extraction of the resulting material in the form of separate particles with a dilute sodium carbonate solution to remove carboxylic acids yielded 26 parts of polyethylene terephthalate, having an average molecular weight of 1028. the reaction product is the ratio of units of ethylene glycol derivatives and; pure nitrogen gives a polymer that is pressed at a temperature. A transparent film is obtained (11-n rac. In ortho-chlorophenol at a temperature of 25 ° C). Example 2. 65 parts of terephthalic acid left in the form of particles having an average particle size of 100 microns are mixed with 0.13 parts of tetraisopropyl titanate and 0.65 parts of three-n-butylphosphine oxide and heated in a fluidized way. layer at a temperature in a stream of nitrogen (7.5 parts per minute). Ethylene glycol vapor (5.5 parts per minute) is fed to the nitrogen stream for 20 hours. The product contains 45 parts of low molecular weight polyethylene terephthalate, with cannabis acids. After heating at a temperature in an atmosphere of pure nitrogen for 20 hours, all the material in the reactor is converted into polyethylene terephthalate in the form of individual particles. The polymer is processed into a transparent film. This example clarifies the importance of limiting the flow of ethylene glycol before all carboxylic acid reacts so that the desired shape is maintained as separate particles. Example 3. 65 parts of terephthalic acid in the form of particles having an average particle size of 100 microns are mixed with 0.13 parts of tetraisopropyl titanate and heated in a reactor operating on the principle of a fluidized bed at a temperature of 6 volts in a stream of nitrogen (7.5 parts per minute). Pairs of ethylene glycol (7.8 parts per minute) are fed to the nitrogen stream over. 20 hours The product is obtained in the form of a transparent molten mass. This example shows that the supply of glycol in the mass of a solid reactant for an unnecessarily long period of time leads to glycolysis and the formation of a molten monomer product. Thus, when implementing the proposed method, the process of obtaining polyethylene terephthalate is simplified (excluding the stage of intermediate curing of the reaction melt and its grinding into parts of the required size). The method of producing poly (ethylene terephthalate) by esterifying terephthalic acid with dylene glycol and polycondensations, characterized in that, in order to simplify the process, the esterification and polycondensation are carried out simultaneously in the solid phase, while the steam glycol glycol is fed into the reaction mixture until the ratio between the curriculum and the curcu- racy of the temperature between the glycer glycol and the polyester condensation is carried out simultaneously in the solid phase, while the steam glycol glycol is fed into the reaction mixture until the ratio between the curriculum and the curcu- racy is carried out simultaneously in the flow range between the curriculum and vane gas are carried out simultaneously in the solid phase. acid Oh, 97g, respectively. Sources of information, received attention in the examination 1. UK patent No. 1066162, cl. C 3 AND, 1967,