JPS5834490B2 - Polyester polymerization reaction equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves the condensation polymerization of linear saturated polyesters, more specifically, the production of polyesters by condensation polymerization under alkylene glycol elimination conditions, in which volatile substances other than alkylene glycol are produced as by-products. The present invention relates to a polymerization reaction apparatus suitable for adding such additives and carrying out condensation polymerization.

Conventionally, dicarboxylic acids such as succinic acid, adipic acid, sepatic acid, terephthalic acid, isophthalic acid, diphenyl dicarboxylic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfonic acid, diphenoxymethane dicarboxylic acid, diphenoxyethane dicarboxylic acid, stilbene dicarboxylic acid acids, one or more aliphatic and aromatic dicarboxylic acids such as diphenylethanedicarboxylic acid, and glycols such as ethylene glycol, trimethylene glycol, propylene gelicol, futhylene gelicol, cyclohexane-1,2-diol, cyclohexane One or two of -1,3-diol, neopentylene gellicol, ■, 4-cyclohexane dimethylol, etc.
Polyesters consisting of more than one species are known.

Among these, it is well known that polyesters obtained from terephthalic acid, naphthalene dicarboxylic acid, and ethylene glycol or tetramethylene glycol have great industrial value as fiber ξ films, resins, etc.

In general, polyesters made of dicarboxylic acids and glycols are made into bis-containers by, for example, transesterification reactions between lower dialkyl esters of dicarboxylic acids and glycols, addition reactions between dicarboxylic acids and alkylene oxides, and ester reactions between dicarboxylic acids and glycols. - The first step of reaction to produce hydroxyalkyl dicarboxylate and/or its low polymer, and the initial condensation product is heated under reduced pressure and/or in an inert gas stream to remove glycol, resulting in polycondensation and high polymerization. It is produced by a second stage reaction of coalescence.

Although the polycondensation reaction proceeds without a catalyst, in that case the reaction is extremely slow, so generally a catalyst such as antimony dioxide or titanium alkoxide is used to improve the polycondensation reaction rate.

However, even if a catalyst is used, this polycondensation reaction takes quite a long time and is carried out at a high temperature of 200'C to 350°C, so side reactions such as thermal decomposition cannot be avoided.
As a result, only a polyester with a high terminal carboxyl group content and poor thermal stability is obtained.

For example, when industrially producing polyethylene terephthalate, 0. 270 under high vacuum of lmmHg to 0.5mmHg
It is necessary to react at a high temperature of 0C to 290C for 2 to 10 hours.

Therefore, in order to increase production at a certain level, huge equipment is required, and it is impossible to avoid an increase in the amount of terminal carboxyl groups in the resulting polymer due to prolonged exposure to high temperatures.

In order to overcome this drawback, one or more types of diaryl carbonates, diaryl dicarboxylic acid esters, aryl orthocarbonates, aryl orthoesters, etc. are added during the polycondensation reaction process of polyester to form terminal carboxyl groups in an extremely short reaction time. Improved polyester production processes are known that produce low amounts of high degree of polymerization polyesters.

Such a method is extremely effective in obtaining a high-quality polyester with a high degree of polymerization, but since the above-mentioned aryl esters and aryl orthoesters are added, phenols and, in some cases, ethylene carbonate and hydroxyl are added during the condensation polymerization. There was a drawback that various troubles occurred during the production and distillation of alkyl formates and subsequent distillation and recovery operations.

In other words, in conventional polymerization reactors, one series of distillation, condensation, and recovery systems is provided corresponding to each polymerization tank, and all distillates are treated in a single path. If the components of the distillate change from glycols to mixed components with phenols, etc., they tend to stick to distillation pipes, condensers, etc., causing problems such as deterioration of vacuum suction and reduction in condensing capacity. There was a drawback that this occurred.

In addition, the single distillation route causes contamination of distillate, and since the boiling points of glycols and phenols are close, separation and purification is extremely difficult and complicated. There was a defect that increased the amount of glycols that were discarded, leading to an increase in production costs.

The present inventors have investigated a polymerization reaction apparatus that eliminates the possibility of contamination of phenols with glycols even when polymerization is carried out by adding the above-mentioned aryl esters and aryl orthoesters. As a result, we have arrived at the present invention.

That is, the present invention cools and collects the distillate generated from the polymerization tank when performing condensation polymerization by adding additives that produce volatile substances other than alkylene glycol as by-products in the polyester polycondensation reaction process. In such a polymerization reaction apparatus, a plurality of condensers with different cooling temperatures are provided, and the distillation pipe of the polymerization tank is forcibly kept warm and connected to each of the condensers through a flow path switching means, so that the distillate is It is characterized in that the condenser is switched and used according to changes in the components.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is a process diagram showing a specific example of the present invention, which is applied to a polyester polymerization reaction in which phenols other than glycols are generated during the reaction process.

In FIG. 1, 1 is a polymerization tank having a stirring blade 2, 3 is a driving device for the stirring blade, 4 is an additive supply tank, and 5 is a jacket-type distillation pipe that is forcibly kept warm by heating fluid. The flow path is branched by a switching valve 6, and one side is connected to a low temperature condenser 7 and the other side is connected to a high temperature condenser 8.

The low and high temperature condensers 7 and 8 are both multi-tube type, and the former is supplied with 20°C cooling water, and the latter is supplied with 40°C hot water as a cooling liquid.

9 is a pot for removing condensate such as phenols, 10.11
1 is a glycol removal pot, and 12 is a vacuum suction tube connected to a vacuum generator (not shown).

Bis-β is placed in the polymerization tank 1 of the polymerization reactor having such a configuration.
-Hydroxyethyl terephthalate and its low polymer are charged and a condensation polymerization reaction is carried out, and the resulting glycol distillate is passed from the distillation pipe 5 through the switching valve 6 to the low temperature condenser 7, and as in the conventional case, the distillate is sent to the take-out box N0, Collected on 11th.

After the polymerization reaction proceeds under these conditions, when a certain condition is reached, diphenyl terephthalate is introduced as an additive from the supply tank 4, and at the same time, the switching valve 6 is operated and the distillate flow path is switched to the high temperature condenser 8 side. .

Therefore, the subsequent distillate is taken out from the high-temperature condenser 8 and placed in a pot 9.
Therefore, troubles such as contamination or clogging as described above are completely prevented, and a stable polymerization reaction is carried out.

In other words, the lower the cooling temperature of the low-temperature condenser 7 is, the better in order to increase the recovery rate of glycols and the degree of polymerization vacuum, and industrial water or recycled recycled water is usually used from an economical and facility standpoint. However, phenols and the like have extremely strong adhesive properties compared to glycols, and under similar conditions, they will adhere and grow due to rapid cooling during condensation, causing problems such as blockage.

However, since the cooling conditions for such adhesion during condensation are relaxed by the high temperature condenser 8 heated above a certain temperature, the above-mentioned troubles can be completely prevented.

In addition, in the polycondensation reaction of polyester, most of the glycols produced as by-products are distilled off during the initial polycondensation, particularly before the intrinsic viscosity of the polyester reaches 0.2, and thereafter only a very small amount of glycols is removed.

Therefore, if the above-mentioned additives are added at a stage where the intrinsic viscosity is relatively high, the by-products such as phenols will adhere to or remain in the distillation tube and will not be washed away by the large amount of glycols generated. However, it will contaminate the glycols generated during the initial polycondensation of the next batch.
In the present invention, the distillation tube 5 is forcibly kept warm (heated) to prevent adhesion and retention, and there is no chance of contamination as described above.

Figure 2 shows another embodiment of the present invention, in which the high-temperature condenser is a spray condenser 13, and a circulation tank 14 with built-in heating and cooling means is installed so that the condensate can be recycled alone or together with a solvent. It is something.

Reference numerals 15 and 16 designate switching valves provided individually, and the rest are the same as in FIG. 1.

The additives used in this example refer to general additives that are added during the polycondensation reaction, particularly after the intrinsic viscosity of the polyester reaches 0.2, and produce volatile compounds as by-products, such as diphenyl carbonate and diphenyl. terephthalate,
Diphenylnaphthalene dicarboxylate, diphenyl oxalate, polyethylene oxalate, di-n-butyl nexalate, phenyl orthocarbonate, hexaphenyl orthoterephthalate, triphenoxy-acetic acid phenyl ester, di-P-chlorophenyl terephthalate, di-P-cushary Examples include butylphenylnafucrene-2,6-dicarboxylate, β-nafbuthiorthocarbonate, and the like.

Bis-hydroxyalkyl dicarboxylate and/or
Examples of low polymers thereof include bis-β-hydroxyethyl terephthalate, bis-δ-hydroxytetramethylene terephthalate, bis-β-hydroxyethyl-
Naphthalene 2,6 dicarboxylate, bis-δ-hydroxytheramethylene naphthalene 2,6-dicarboxylate, bis-β-hydroxyethyl 44/diphenyl dicarboxylate, etc., and/or mixtures thereof and low polymers thereof. In some cases, one part of the dicarboxylic acid and one part of the glycol may be replaced with other types.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 194 dimethyl terephthalate was added to the polymerization tank 1 shown in Figure 1.
parts, 130 parts of ethylene glycol, 0.0 parts of calcium acetate.
Bis-β-human, loxethyl terephthalate and its low polymer obtained by subjecting 176 parts to a Tennis chill exchange reaction at a temperature of 140°C to 230°C, antimony dioxide as a catalyst, 0.088% phosphorous acid as a stabilizer, 0.
082 parts and heated at 240-260°C under atmospheric pressure.
Under high vacuum from 760 to BmiHg 275 to 2800 for 5 minutes
The molds were matched for 90 minutes at c.

Ethylene glycol distilled during this time was condensed in a low-temperature cooler 7 and collected in take-out pots 10 and 11.

After that, the switching valve 6 (three-way valve) was connected to the high temperature condenser 8 side, and 1.9 parts of diphenyl terephthalate in the reaction system was added under vacuum.The intrinsic viscosity of the polyester was 0.94 in 60 minutes. Met.

Here, the polymerization tank 1 was pressurized to 3.0 kg/- and 172 parts of polyethylene terephthalate was taken out from the lower part.

Thereafter, ethylene glycol was taken out from the take-out pots 10 and 11, and a phenol/glycol mixture was taken out from the take-out pot 9.

Thereafter, the same amounts of bis-β-hydroxyethyl terephthalate and its low polymer catalyst stabilizer as above were charged again to polymerization tank 1, and polycondensation was carried out in the same manner.

However, the amount of diphenyl terephthalate added was 2.1 parts.

After the completion of the reaction, no phenol was detected in the ethylene glycol taken out from the take-out pots 10 and 11, and 2.4 parts of a glycol/phenol mixture having a phenol content of 32% by weight was taken out from the take-out pot 9.

During this time, hot water with a water temperature of 40°C was used as a cooling fluid in the high temperature condenser 8, and cold water with a water temperature of 20°C was used in the low temperature condenser 7.

Further, the distillation tube 5 was heated and kept warm with a heating medium at 220°C.

The above operation was repeated 100 times, but the distillation tube 5
There was no trace of distillate adhering to the high temperature condenser 8.

Comparative Example For comparison, the same condensation polymerization as in the example was carried out with the switching valve 6 set to the low-temperature condenser 7 side, and the distillate was transferred to the take-out pot 11 before the additive was supplied, and to the take-out pot 10 after the additive was supplied. 0.4% of phenol, which should not originally be present, was detected in the ethylene glycol taken out from the take-out pot 11 after the completion of the condensation polymerization of the second batch, and 6.4% of phenol was detected from the take-out pot 10. Ta.

In addition, when the cooling temperature of both the low and high temperature condensers was set to 20°C and the same procedure as in the example was carried out, the degree of vacuum from the low condenser 7 side deteriorated from around 2° batches, and when the low temperature condenser 7 was disassembled after 30 batches, distillation occurred. The inlet of the cooling pipe was almost completely blocked by something attached to it.

As described above, in the present invention, a plurality of condensers having different cooling temperatures are provided, and the distillation pipe of the polymerization tank is forcibly kept warm, and is branched into communication with each of the condensers via the flow path switching means. Optimal condensation and separation can be carried out without troubles such as blockage and contamination due to distillate in response to changes in distillate components, and especially in the case of a batch system, it has the great effect of allowing stable condensation and polymerization reactions to be carried out repeatedly.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a specific example of the present invention, and FIG. 2 is a process diagram showing another specific example. 1 is a polymerization tank, 4 is an additive supply tank, 5 is a distillation pipe, 6 is a switching valve, 7 is a low temperature condenser, 8 is a high temperature condenser, 9.10,1
1 is a take-out pot, 13 is a spray set condenser, 14 is a circulation tank, and 15 and 16 are switching valves.

Claims (1)

[Claims] 1 A polyester in which additives that produce volatile substances other than alkylene glycol as by-products are added during the polyester polycondensation reaction process, and the distillate generated from the polymerization tank during polycondensation is cooled and collected in a condenser. In this polymerization reaction apparatus, a plurality of condensers with different cooling temperatures are provided, and the distillate pipe of the polymerization tank is forcibly kept warm and branched into communication with each of the condensers via a flow path switching means, and the distillate components are 1. A polyester polymerization reaction apparatus characterized in that a condenser is switched in accordance with changes in the amount of water.