JPS5822097B2 - Method for producing bis-(β-hydroxyethyl) terephthalate and/or its low polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing bis-(β-hydroxyethyl) terephthalate and/or its low polymer (hereinafter referred to as BHET).

Specifically, the present invention relates to an improvement in a method for producing BHET by directly reacting terephthalic acid (hereinafter abbreviated as TPA) and ethylene glycol (hereinafter abbreviated as TEG).

As an industrial method for producing polyester mainly composed of polyethylene terephthalate, which is useful as a material for fibers, films, molded products, etc., TPA or a mixture of TPA and another third component is directly reacted with EG, and then polycondensation is performed. Direct polymerization methods are known.

However, since TPA is poorly soluble in EG, the reaction between TPA and EG inevitably results in a heterogeneous reaction.

In particular, when the reaction is carried out with a relatively small amount of EG, for example, less than twice the molar amount of TPA, TPA becomes moist lumpy or muddy due to EG, reducing the heat transfer effect, and as a result, the temperature rises to the reaction humidity. It takes a lot of time.

On the other hand, when the reaction is carried out using a large excess of EG, the above-mentioned drawbacks are improved, but the etherification reaction occurs as a side reaction and diethylene glycol (hereinafter abbreviated as DEC) is produced as a by-product, resulting in softening of the resulting polyester. There were drawbacks such as a decrease in the score and deterioration of other physical properties.

For this reason, various improvement methods have been proposed in the past, but
None of these methods can necessarily be said to be industrially satisfactory.

As a production method that achieves a sufficient reaction rate and produces less by-product DEC, [TPA is dissolved or suspended in a liquid third component under reaction conditions to a TPA solution or suspension at a temperature higher than the dew point of EG]. Method 1 of reacting gaseous EG (
(Japanese Patent Publication No. 46-22463) further develops the above method by saying,
"A method of partially condensing a gas containing G and circulating the resulting partial condensate to a reactor and/or raw material feed thread" (JP-A-49-800
No. 33) is known.

As a result of intensive research to improve the above method to make it more industrially advantageous, the present inventors found that during esterification, the partial pressure of EG in the gas phase of the reaction system was maintained within a certain range to carry out the reaction. The present inventors have discovered that by subjecting BHET to a polycondensation reaction, the softening point of the resulting polyester is improved and the reaction rate of the polycondensation is significantly increased.

That is, the present invention involves reacting terephthalic acid and ethylene glycol with a solution or suspension of terephthalic acid in which terephthalic acid is dissolved or suspended in a liquid third component under reaction conditions at a humidity higher than the dew point of ethylene glycol. Sebisu (β
- In the method for producing hydroxyethyl terephthanate and/or its low polymer, the partial pressure of ethylene glycol in the gas phase within the reaction system is adjusted from 400 mmHg to 15 mmHg.
A method for producing bis-(β-hydroxyethyl→teV phthanate and/or a low polymer thereof) characterized in that the reaction is carried out while maintaining the temperature in the range of 0 mmHg.

The present invention will be explained in detail below.

In the process of the present invention, a solution or suspension of TPA is typically prepared by mixing powdered TPA with liquid EG, then feeding this slurry into a reactor and mixing with a liquid third component under reaction conditions.

The third component that dissolves or suspends TPA is:

BHET is the most commonly used, but it reacts with EG to form BHET.
Other TPA derivatives capable of producing HET can also be used, such as dimethyl terephthalate, monomethyl terephthalate, methyl ethyl terephthanate, diethyl terephthalate, and the like.

. The amount of these third components to be used may be at least the amount that forms a solution or suspension of TPA under the reaction conditions;
It is preferable to use approximately the same weight as A or more.

To carry out the present invention, the TP prepared as described above is used.
A solution or suspension of A under reaction conditions.

The EG contained in the TPA solution or suspension is kept at a temperature above the dew point of the EG, or the EG contained in the TPA solution or suspension is vaporized or
This is done by introducing G.

The introduced EG does not necessarily have to be in a gaseous state, and may be introduced in a liquid state and then vaporized.

Usually dissolved in TPA. Vaporize the EG contained in a liquid or suspension.

Although the reaction in the method of the present invention is carried out at a temperature above the dew point of EG under the reaction conditions, it is advisable to carry out the reaction at normal pressure from the viewpoint of operation and equipment.

The humidity in this case is preferably selected from the range of EG's boiling point (197°C) or higher, preferably from 220 to 290°C.

Of course, the reaction can be carried out under increased pressure or reduced pressure, as long as EG is not substantially present in liquid form and the partial pressure of EG in the gas phase in the reaction system is in the range of 440 mmHg to 150 mmHg. can.

In the present invention, the partial pressure of EG in the gas phase within the reaction system is reduced to 400%.
It is an essential requirement to maintain it within the range of mmHg to 150rfLrILHg.

Most of the gases present in the gas phase in the reaction system are TPA and E.
Water and excess EG are by-produced during the esterification of G, and various methods can be used to maintain the partial pressure of EG in the gas phase within the above range.

For example, 0 A method of continuously adding EG according to the amount of by-produced filtrate depending on the esterification rate 0 A method of continuously adding EG according to the amount of by-produced filtrate 0 A method of adding EG continuously according to the amount of by-produced filtrate 0 A method of adding EG continuously according to the amount of by-produced filtrate 0 Method for adjusting the continuous withdrawal amount of the circulating liquid when separating the generated gas and circulating the separated EG to the reactor θ Separating the gas generated from the reactor in a reactor equipped with a demultiplexer. A method for adjusting the partial condensation rate in the partial condenser when circulating the Naro partial condensate mainly from EG to the reactor. Examples include a method of diluting EG in the gas phase within the reaction system, but any method may be used. mmHg to 150 mm) (Any method that can maintain the temperature at g) may be used.

In the present invention, when the partial pressure of EG in the gas phase in the reaction system is 40017XiHg or more, the esterification reaction rate becomes faster, but the softening point of the polyester is or the reactivity of polycondensation is not achieved.

On the other hand, if it is less than 150 mmHg, the esterification reaction rate becomes slow, which is not preferable from an industrial standpoint.

The reaction in the method of the present invention may be carried out either in the presence or absence of a catalyst.

When a catalyst is used, any known catalyst effective for esterification can be used.

The amount used varies depending on the type of catalyst, but usually TPA
A weight ratio of 0.001 to 0.5 is suitable.

BHET produced in the present invention is usually obtained as a low polymer with an average degree of polymerization of 4 to 8 molecules, but depending on the reaction conditions, it can be obtained as a monomer or a relatively high molecular weight low polymer. In some cases.

Although the method of the present invention is suitable for continuous production, it is of course possible to satisfactorily achieve the object of the present invention even in a batch method.

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 unless it exceeds the gist thereof.

In addition, in the examples, parts indicate parts by weight.

In addition, the intrinsic viscosity [η] is phenol:tetrachloroethane (
1:1) solvent at 30°C.

Example 1 B synthesized by a known method from a stirrer-equipped reactor KTPA and EG having a separation column in which the reflux liquid is directly refluxed to the reactor.
100 parts of HET was charged and maintained at 250°C and normal pressure.

A slurry obtained by pre-mixing 100 parts of powdered TPA and 48 parts of EG was continuously charged into this reactor for 4 hours to carry out a reaction.

During this time, the gas evaporated from the reactor is separated from the EG component in the separation column, and the water is taken out of the system from the top of the separation column, and the EG component is transferred to the reactor.The partial pressure of EG in the gas phase of the reactor becomes 38 parts mmHg. Excess refluxed EG was extracted in liquid form from the bottom of the separation column and refluxed.

After the completion of slurry preparation, the same temperature and pressure were maintained for an additional 30 minutes to obtain a transparent BHET.

Esterification rate of this product (carboxyl group of TPA)
is ivy at 95.5%.

100 parts of this BHET was transferred to a vacuum polycondensation chamber, and antimony trioxide was added at a weight ratio of 0.03 to the BHET, the pressure was reduced to 10 mmHg in 1 hour, and then polycondensation was carried out at 280° C. under high vacuum.

The polycondensation time required for this was 4 hours.

The obtained polyester had a [η] of 0466 and a softening point of 260.0°C.

Example 2 The procedure of Example 1 was repeated, except that the slurry was charged for 4 hours and 30 minutes, and the partial pressure of EG in the gas phase of the reactor was 300 mmHg. The reaction was carried out in the same manner.

When polycondensation was carried out using the obtained BHET under the same conditions as in Example 1, the time required for polycondensation was 3 hours 30 minutes.
The [η] of polyester is 0.66, and the softening point is 2.
The temperature was 61.0°C.

Example 3 The procedure was the same as in Example 1, except that the slurry was charged for 5 hours and 30 minutes, and excess EG was extracted from the bottom of the separation column so that the partial pressure of EG in the gas phase of the reactor was 200 mmHg. The reaction was carried out.

The time required for polycondensation of the obtained BHET (the conditions of the polycondensation stage were the same as in Example 1) was 3 hours and 15 minutes, and the [η] of the polyester was 0.66, and the softening point was 262.1°C. Met.

Example 4 The apparatus shown in Example 1 was charged with 00 parts of BHETl synthesized from TPA and EG by a known method, and maintained at 250°C and normal pressure.

A slurry obtained by previously mixing 100 parts of powdered TPA and 39.2 parts of EG was charged into this reactor for 5 hours and a reaction was carried out.

During this time, the gas evaporated from the reactor was separated in a separation column, the by-produced filtrate was taken out of the system from the top of the separation column, and the entire amount of EG was circulated to the reactor.

In this case, the partial pressure of EG in the gas phase of the reactor is 250 mm.
It was Hg.

Clear BHE after holding for 30 minutes after slurry preparation
I got a T.

When this BHET was polycondensed in the same manner as in Example 1, the polycondensation time was shortened to 3 hours and 25 minutes, the [η] of the polyester was 0.66, and the softening point was 261.
．． The temperature was 5°C.

Example 5 100 parts of BHET synthesized from TPA and EG by a known method was charged into the same apparatus as used in Example 1, and heated at 260°C.
The pressure was maintained at normal pressure.

A slurry prepared by mixing 100 parts of powdered TPA and 43 parts of EG was charged into this reactor in advance at a rate of 36 parts/hr.

The gas evaporated from the reactor was separated in a separation column, and the by-product water was extracted from the top of the separation column at a rate of 5.2 parts/hr, and the partial pressure of EG in the gas phase of the reactor was adjusted to 380 mmHg IL. Excess refluxed EG was continuously extracted in liquid form from the bottom of the separation thread.

On the other hand, the reaction solution was poured into the overflow tube at 29 parts/hr.
, I extracted it with .

The esterification rate of this BHET was 95%.

100 parts of the BHET thus obtained were transferred to a vacuum condensation table can, and antimony trioxide was added to the BHET by weight of 003, and the pressure was reduced to 10 mmHg for 1 hour.
It was heated to 80°C to cause polycondensation.

The polycondensation time required for this was 3 hours and 40 minutes.

Furthermore, the obtained polyester had a [η] of Q, 66, and a softening point of 261.0°C.

Example 6 The apparatus used in Example 1 was charged with 100 parts of BHET synthesized from TPA and EG by a known method and maintained at 260°C and normal pressure.

In this reactor, 100 parts of powder TPA, 43 parts of EG and 16 parts of water were added.
A slurry obtained by pre-mixing the two parts was continuously charged for 4 hours and a reaction was carried out.

During this time, the gas evaporated from the reactor was separated in a separation column, the by-product water was taken out of the system from the top of the separation column, and the entire amount of EG was circulated to the reactor.

In this case, the partial pressure of EG in the gas phase of the adder is 200m71L
It was Hg.

After slurry preparation is completed, keep it under the opening conditions for 30 minutes and make a transparent B.
I got HET.

This BHET was polycondensed in the same manner as in Example 1.

The polycondensation time in this case is 3 hours and 20 minutes, the [η] of the polyester is 0.66, and its softening point is 261.5°C.
Met.

Comparative Example 1 The apparatus shown in Example 1 was charged with 100 parts of BHET synthesized from TPA and EG by a known method and maintained at 250° C. and atmospheric pressure.

A slurry obtained by pre-mixing 100 parts of powdered TPA and 63.5 parts of EG was continuously charged into this reactor for 4 hours to carry out a reaction.

During this time, the gas evaporated from the reactor was separated in the separation column, water produced as a by-product was taken out from the top of the separation column, and the entire amount of EG was circulated to the reactor.

In this case, the partial pressure of EG in the gas phase of the reactor is 550 mm.
It was Hg.

After slurry preparation, a transparent BHET was obtained.
were polycondensed in the same manner as in Example 1.

In this case, the polycondensation time was 4 hours and 40 minutes, the [η] of the polyester was 066, and its softening point was 259.3°C.
Met.

Comparative Example 2 The same reaction as in Example 1 was carried out except that the slurry was charged for 3 hours and 30 minutes and EG was not extracted from the lower part of the separation column.

When polycondensation was carried out using the obtained BHET under the same conditions as in Example 1, the time required for polycondensation was 4 hours 30 minutes.
The [η] of the polyester was 0.66, and the softening point was 259.5°C.

Comparative Example 3 The reaction was the same as in Example 1, except that the slurry was charged for 7 hours and 30 minutes, and excess EG was extracted from the bottom of the separation column so that the partial pressure of EG in the gas phase of the reactor was 140 mmHg. When this was carried out, the esterification reaction was slow and transparent.
ET was not obtained.

Example 7 100 parts of powder TPA and E were used as a slurry to be charged into the reaction system.
Using a slurry obtained by pre-mixing EG with 93.3 parts, this slurry was prepared in 4 hours and 30 minutes, and the entire amount of gas generated from the reactor was extracted outside the reaction system, and the partial pressure of EG was adjusted to 300 mmHg. The same reaction as in Example 1 was carried out except for the following adjustments.

When polycondensation was carried out using the obtained BHET under the same conditions as in Example 1, the time required for polycondensation was 4 hours, the [η] of the polyester was 066, and the softening point was 2610 ° C. .

Example 8 100 parts of powder TPA and E were used as a slurry to be charged into the reaction system.
The same reaction as in Example 7 was carried out except that a slurry obtained by pre-mixing 74.7 parts of G and 74.7 parts was used and the slurry was charged over a period of 5 hours and 30 minutes.

The EG partial pressure in the gas phase at this time was 230 mmHg.

When polycondensation was carried out using the obtained BHET under the same conditions as in Example 1, the time required for polycondensation was 3 hours and 1 hour.
5 minutes, polyester [η] is 066, softening point is 262
．． The temperature was 1°C.

Example 9 Esterification reaction The same reaction as in Example 1 was carried out except that the humidity was 260° C. and the slurry was charged for 3 hours and 30 minutes.

The EG partial pressure in the gas phase at this time was 230 mmHg.

When polycondensation was carried out using the obtained BHET under the same conditions as in Example 1, the time required for polycondensation was 3 hours.
The [η] of polyester is 0.66, and the softening point is 262.
．． The temperature was 2°C.

Comparative Example 4 A slurry obtained by pre-mixing 100 parts of powdered TPA and 168 parts of EG was used as a slurry to be charged into the reaction system.
Example 7 except that this slurry was prepared for 3 hours.
A similar reaction was carried out, and the EG partial pressure in the gas phase was 4.
It was 80 mmHg.

When polycondensation was carried out using the obtained BHET under the same conditions as in Example 1, the time required for polycondensation was 4 hours and 40 minutes.
The [η] of the polyester was 0.66, and the softening point was 259.5°C - Table 1 below shows the results of Examples 1 to 9 and Comparative Examples 1 to 4.

Claims (1)

[Claims] 1 Bis(β- In the method for producing (hydroxyethyl) terephthalate and/or its low polymer, the partial pressure of ethylene glycol in the gas phase in the reaction system is adjusted from 400 yu+, Hg to 150 mmI (g
Bis-(
A method for producing β-hydroxyethyl) terephthalate and/or a low polymer thereof.