JP2005076010A - Oligomer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oligomer capable of giving an excellent color tone and a low content of ether bonds as a by-product to polytrimethylene terephthalate obtained therefrom, and to provide a method for producing the oligomer, excellent in stability of continuous reaction processes. <P>SOLUTION: An ester and/or the oligomer thereof are obtained from a lower alcohol ester of terephthalic acid and 1,3-propanediol, wherein the ester and/or the oligomer satisfy requisites (1) to (5) as follows: main repeating units thereof are composed of trimethylene terephthalate; (2) an average polymerization degree thereof is in the range of 1.5 to 7; (3) cyclic oligomers are contained in a range of 0 to 2.2 wt% based on the ester and/or the oligomer which are obtained from the lower alcohol ester of terephthalic acid and the 1,3-propanediol; (4) hydroxy groups are contained in a range of 92 to 100 mol wt% based on total end groups of the ester and/or the oligomer which are obtained from the lower alcohol ester of terephthalic acid and the 1,3-propanediol; and (5) bis(3-hydroxypropyl)ether is contained in the range of 0-0.3 wt%. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to an oligomer of polytrimethylene terephthalate and a method for producing the same. More specifically, since there are few troubles due to scattering of cyclic oligomers and lower alcohol esters of terephthalic acid, the stability of the continuous reaction process is excellent, the color tone of the resulting polytrimethylene terephthalate is excellent, and there are few by-product ether bonds. The oligomer and its manufacturing method.

  Polytrimethylene terephthalate (hereinafter abbreviated as PTT) is made into a fiber by melt spinning, and has a soft texture derived from a low elastic modulus, excellent resilience, easy dyeability and properties similar to nylon. It is an epoch-making fiber that has properties similar to polyethylene terephthalate fibers such as and wear resistance, dimensional stability, and yellowing resistance, and is being applied to clothing, carpets, etc., taking advantage of its characteristics. In addition, because of the ease of processing due to the high crystallization speed, dimensional stability, and yellowing resistance, application development has also been promoted for resins and films, and PTT has received much attention. It is a polymer.

PTT is similar in chemical structure to polyethylene terephthalate (hereinafter abbreviated as PET) and polybutylene terephthalate (hereinafter abbreviated as PBT), and a lower alcohol ester of terephthalic acid and 1,3-propanediol. Can be polymerized in a molten state using an organotitanium compound as a catalyst to obtain a polymer.
However, in a continuous reaction that produces PTT on an industrial scale, the by-product gas line of the transesterification reaction or polycondensation reaction may be clogged due to the adhesion of low molecular weight compounds that did not become noticeable in small-scale batch reactions. I understood. For example, if clogging occurs in the vacuum line of the by-product gas line of the polycondensation reaction, the reaction pressure in the polycondensation process becomes high, so that the by-product 1,3-propanediol is difficult to escape from the reaction system. The average degree of polymerization of the resulting polymer will be small. In order to remove the adhering low molecular weight compounds, it can be removed with a removal device provided in the vacuum line, but even in that case, the average polymerization degree is reduced until the removal device is completely operated, resulting in production loss. End up. In severe cases, the vacuum line may have to be dismantled, in which case production losses can last for several days. Such a problem of clogging of the vacuum line is an important issue in both the process stability and the quality stability in the continuous reaction.

  The main low-molecular compounds adhering to the by-product gas line are cyclic oligomers mainly composed of a raw material lower alcohol ester of terephthalic acid and a cyclic dimer. When a large amount of the lower alcohol ester of terephthalic acid as raw material adheres to the by-product gas line, the reaction rate of the transesterification reaction is small, and there are many unreacted lower alcohol esters of terephthalic acid in the reaction product. is there. Therefore, in order to reduce the concentration of the lower alcohol ester of terephthalic acid, it is necessary to increase the reaction rate of the transesterification reaction. As a result, the average degree of polymerization of the reaction product is increased. Moreover, when many cyclic oligomers adhere to a by-product gas line, it is a case where many cyclic oligomers exist in a reaction material. In order to reduce the concentration of the cyclic oligomer, the cyclic oligomer has an equilibrium value of about 2.5% by weight with respect to the reactant when the PTT exceeds a certain average degree of polymerization. It is necessary to reduce the average degree of polymerization.

  Thus, the idea of reducing the concentration of the lower alcohol ester of terephthalic acid and the cyclic oligomer in the reaction product adhering to the by-product gas line is contradictory. In order to reduce the average degree of polymerization and increase the transesterification reaction rate, the raw material molar composition ratio (hereinafter abbreviated as G value) of 1,3-propanediol to the lower alcohol ester of terephthalic acid is increased. Thus, low molecular compounds adhering to the by-product gas line are reduced, but a large amount of bis (3-hydroxypropyl) ether (hereinafter abbreviated as BHPE) generated by the side reaction is incorporated into the PTT skeleton as a copolymer. As a result, PTT obtained by the subsequent polycondensation reaction has poor thermal stability and weather resistance.

There are several proposals regarding the continuous reaction of PTT. (For example, refer to Patent Documents 1 and 2) However, in these proposals, since there is no recognition of the problem of clogging due to adhesion of low-molecular compounds in by-product gas lines in continuous reaction, when we actually conducted a supplementary test, Cyclic oligomers and unreacted lower alcohol esters of terephthalic acid adhered to the by-product gas line, and side reaction BHPE increased.
Thus, in the continuous reaction of PTT, there is no problem of clogging due to adhesion of low molecular weight compounds to the by-product gas line, and it is obtained from a lower alcohol ester of terephthalic acid and 1,3-propanediol with little side reaction and Or there has never been a proposal for oligomers.
International Publication No. 2000/64962 Pamphlet International Publication No. 2001/58982 Pamphlet

  The problem to be solved by the present invention is that there is little scattering of low-molecular compounds in the transesterification step and polycondensation reaction step of the continuous reaction process of PTT, so that the stability of the continuous reaction process can be ensured and obtained. It is to provide an oligomer in which the resulting PTT is reduced in side reaction BHPE and to provide a production method thereof.

  In order to solve the above-mentioned problems, the present inventors have intensively studied the physical properties of PTT oligomers by paying attention to the stability of the continuous reaction process and the quality of the obtained PTT. As a result, the transesterification step and the polycondensation reaction can be performed only when the physical properties of the oligomer of PTT are within a specific range, such as the average degree of polymerization, the concentration of cyclic oligomers, the proportion of hydroxyl groups of terminal groups, and the concentration of by-produced ether bonds It was found out that the by-product gas distillation line in the process could be blocked, PTT having excellent color tone and low ether bond concentration was obtained. As a result of further detailed studies, the present invention has been achieved.

That is, the present invention is an ester and / or oligomer obtained from a lower alcohol ester of terephthalic acid and 1,3-propanediol satisfying the following (1) to (5).
(1) The main repeating unit is composed of trimethylene terephthalate.
(2) The average degree of polymerization is in the range of 1.5-7.
(3) The cyclic oligomer is in the range of 0 to 2.2% by weight based on the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol.
(4) The hydroxyl group is in the range of 92 to 100 mol% among all terminal groups of the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol.
(5) Bis (3-hydroxypropyl) ether is in the range of 0 to 0.3% by weight.

(1) will be described. The PTT targeted by the present invention is one in which the main repeating unit is composed of a trimethylene terephthalate unit of the following formula [1]. Specifically, the repeating unit of trimethylene terephthalate is 80 to 100% by weight, and 0 to 20% by weight is the other copolymer component as long as the object of the present invention is not impaired. Examples of such copolymer components include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 4-sodium sulfo-2,6-naphthalenedicarboxylic acid, 3,5-dicarboxylic acid benzenesulfonic acid tetramethylphosphonium salt, Esters such as 3,5-dicarboxylic acid benzenesulfonic acid tetrabutylphosphonium salt, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentamethylene glycol A forming monomer may be mentioned.

  Next, (2) will be described. The average degree of polymerization needs to be in the range of 1.5-7. By making the average degree of polymerization greater than 1.5, an increase in BHPE can be suppressed in the subsequent polycondensation step. In order to suppress the increase in BHPE, the higher the average degree of polymerization, the better. Conversely, by making the average degree of polymerization smaller than 7, the concentration of the cyclic oligomer can be reduced, so that the blockage of the byproduct gas line can be reduced. More preferably, the average degree of polymerization is in the range of 2 to 5 from both aspects of suppression of BHPE and reduction of cyclic oligomer concentration.

  Next, (3) will be described. The cyclic oligomer is in the range of 0 to 2.2% by weight based on the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol. When the amount of the cyclic oligomer is less than 2.2% by weight, the amount of the cyclic oligomer scattered in the by-product gas line is reduced, and the by-product gas line is hardly blocked. In particular, since the frequency of clogging in the vacuum line of the polycondensation process is reduced, troubles such as pressure fluctuations are reduced, and as a result, the average degree of polymerization, BHPE, color tone and the like of the obtained PTT are stabilized. Preferably, it is 0 to 2.0% by weight, and more preferably 0 to 1.7% by weight.

  Next, (4) will be described. Of all the terminal groups of the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol, the hydroxyl group is in the range of 92-100 mol%. If it is 92 mol% or more, since the scattering of unreacted lower alcohol ester of terephthalic acid in the transesterification reaction process or the polycondensation reaction process is reduced, the blockage of the by-product gas line is reduced. Stabilized. Preferably it is 95 mol-100%.

Next, (5) will be described. It is necessary that BHPE is in the range of 0 to 0.3% by weight. When BHPE is 0.3% by weight or less, the BHPE of PTT obtained by the subsequent polycondensation decreases. As a result, PTT excellent in heat resistance and weather resistance can be obtained. Fibers, films, and molded products obtained by processing using such PTT also have excellent heat resistance and weather resistance. From the viewpoint of heat resistance and weather resistance, it is preferable that BHPE is small. Preferred BHPE is 0 to 0.15 wt%, more preferably in the range of 0 to 0.08 wt%. Next, esters obtained from lower alcohol esters of terephthalic acid and 1,3-propanediol and A method for producing the oligomer will be described. The production method of the present invention is characterized by satisfying the following requirements when an ester and / or an oligomer thereof are produced by reacting a lower alcohol ester of terephthalic acid with 1,3-propanediol in the presence of a catalyst. This is a continuous transesterification method.

(1) The number of transesterification reaction tanks is in the range of 2-4.
(2) The molar ratio of 1,3-propanediol to the lower alcohol ester of terephthalic acid is in the range of 1.2 to 1.7.
(3) The reaction temperature of the first transesterification reaction tank is in the range of 170 ° C to 200 ° C, and the transesterification rate of the reactant obtained from the reaction tank is in the range of 75 to 90%.
(4) The reaction temperature of the final transesterification reaction tank is in the range of 200 ° C to 235 ° C, and the transesterification rate of the reactant obtained from the reaction tank is in the range of 92 to 100%.
(5) The reaction pressure of all the transesterification reaction tanks is in the range of 80 kPa to 120 kPa.
(6) The addition amount of the titanium compound catalyst to the transesterification reaction tank is in the range of 30 to 150 ppm as a titanium element with respect to the lower alcohol ester of terephthalic acid.

In the continuous transesterification reaction of the present invention, raw materials 1,3-propanediol and lower alcohol ester of terephthalic acid are constantly supplied to the transesterification reaction tank, and the oligomer is discharged from the oligomer discharge part of the transesterification reaction tank. Which is distinct from the batch reaction method.
Specific examples of the lower alcohol ester of terephthalic acid used in the present invention include dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, and dibutyl terephthalate.

Hereinafter, (1) to (6) will be described in detail.
First, (1) will be described. In the continuous transesterification reaction, the number of reaction tanks in the transesterification reaction process must be 2 to 4 tanks. By setting the number of reaction tanks in the transesterification step to two or more, the reaction temperature can be increased stepwise, so that scattering of the lower alcohol ester of terephthalic acid in the first tank can be suppressed. Further, side reaction BHPE can be suppressed by increasing the reaction temperature stepwise. Moreover, construction cost and running cost can be suppressed by using 4 tanks or less. A preferable number of transesterification reaction tanks is 2 to 3 tanks.

  Next, (2) will be described. The molar ratio of 1,3-propanediol to the lower alcohol ester of terephthalic acid ranges from 1.2 to 1.7. By making the molar ratio 1.2 or more, it becomes easy to increase the reaction rate of the transesterification reaction, and as a result, the concentration of the lower alcohol ester of unreacted terephthalic acid can be reduced. Blockage by terephthalic acid lower alcohol ester in the by-product gas line can be suppressed. Moreover, even when the transesterification reaction rate is increased by setting the molar ratio to 1.2 or more, the average polymerization of the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol obtained. Since the degree becomes smaller, the concentration of the cyclic oligomer becomes smaller, and the amount of the cyclic oligomer adhering to the by-product gas line of the polycondensation reaction can be reduced. Conversely, BHPE can be suppressed by setting the molar ratio to 1.7 or less. A preferred molar ratio is in the range of 1.3 to 1.6.

  Next, (3) will be described. The temperature of the first transesterification reaction tank is 170 ° C to 200 ° C, and the transesterification rate of the reactant obtained from the reaction tank is in the range of 75 to 90%. By setting the temperature of the first transesterification reaction tank to 170 ° C. or higher, the reaction rate increases and the residence time can be shortened. Conversely, by setting the temperature to 200 ° C. or lower, it is possible to suppress clogging of the raw material terephthalic acid lower alcohol ester into the by-product gas line. By making the transesterification rate of the first reactant 75% or more, it is possible to suppress clogging of the raw material terephthalic acid lower alcohol ester into the by-product gas line. If the transesterification rate is 90% or less, the reaction can be performed in a relatively short time, so that BHPE can be suppressed. Accordingly, the initial reaction temperature is in the range of 170 ° C to 200 ° C, more preferably in the range of 175 ° C to 195 ° C. The transesterification rate must be in the range of 75 to 90%, preferably 80 to 85%.

Next, (4) will be described. The reaction temperature in the final reaction vessel of the transesterification reaction vessel is 20
It is in the range of 0 ° C. to 235 ° C., and the transesterification rate is in the range of 92 to 100%. By setting the reaction temperature to 200 ° C. or higher, the reaction time can be shortened, and the transesterification rate can be set to 92% or higher. As a result, adhesion of unreacted lower alcohol ester of terephthalic acid to the by-product gas line can be reduced. Conversely, an increase in BHPE can be suppressed by setting the temperature to 235 ° C. or lower. From the viewpoint of suppressing the scattering of the lower alcohol ester of terephthalic acid and suppressing the increase in BHPE, the reaction temperature of the final reaction vessel is in the range of 200 ° C to 235 ° C, and more preferably in the range of 210 ° C to 230 ° C.

  Next, (5) will be described. The transesterification reactor pressure ranges from 80 kPa to 120 kPa. By setting the pressure in the transesterification reaction tank to 80 kPa or more, it is possible to reduce the unreacted lower alcohol ester of terephthalic acid from being scattered in the methanol distillation line, and 1,3-propanediol as a raw material is outside the reaction system. Can be prevented from being distilled off. On the contrary, by making it 120 kPa or less, a by-product becomes easy to distill out of the system, and the reaction can be advanced promptly. Thus, from the viewpoint of suppressing the evaporation of the raw materials and promptly proceeding the reaction, the pressure in the reaction vessel must be 80 kPa to 120 kPa, and preferably in the range of 90 kPa to 110 kPa.

  Next, (6) will be described. The addition amount of the titanium compound catalyst to the transesterification reactor is in the range of 30 to 150 ppm in terms of titanium element with respect to the lower alcohol ester of terephthalic acid. By making it 30 ppm or more with titanium element, the transesterification reaction time can be shortened, the increase in BHPE obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol obtained can be suppressed, and the color tone Deterioration can be prevented. On the contrary, by setting it to 150 ppm or less, the deterioration of the color tone considered to be caused by the titanium compound of the catalyst can be reduced. From the viewpoint of reaction rate and quality, the amount of titanium element must be in the range of 30 to 150 ppm, and preferably in the range of 50 to 120 ppm. Moreover, as a titanium compound used here, titanium alkoxides, such as titanium tetrabutoxide and titanium isopropoxide, are preferable.

Next, a preferred method for adding a catalyst of the present invention will be described.
The titanium compound catalyst is preferably mixed with 1,3-propanediol before the transesterification reaction. If the titanium compound catalyst is directly added to the transesterification reaction tank, the inlet of the titanium compound catalyst is likely to be clogged due to precipitation of the titanium compound catalyst, and it is difficult to stably add the catalyst. In order to suppress precipitation, it is preferable to reduce the concentration of the titanium compound catalyst by mixing with 1,3-propanediol. Moreover, it is preferable that the temperature of 1, 3- propanediol at the time of mixing a titanium compound catalyst is the range of -20 degreeC-30 degreeC.

  The titanium compound catalyst is generally used as a catalyst such as polyethylene terephthalate or polybutylene terephthalate, but the titanium compound catalyst may be mixed with ethylene glycol or butanediol as a raw material at a temperature exceeding 30 ° C. Although it is very difficult to precipitate, 1,3-propanediol is precipitated when mixed at a temperature exceeding 30 ° C. In particular, the higher the temperature, the more intense the precipitation. The deposited titanium compound catalyst not only reduces the activity of the catalyst but also becomes a foreign substance. If a fiber is formed using PTT containing foreign matter, problems such as thread breakage occur. We have found that it is preferable to mix at a low temperature in order to suppress precipitation. The temperature is 30 ° C. or lower, and by setting the temperature to 30 ° C. or lower, precipitation of the titanium compound catalyst can be suppressed. By setting the temperature of 1,3-propanediol to −20 ° C. or higher, the viscosity of 1,3-propanediol can be lowered, and mixing with the titanium compound catalyst can be sufficiently performed. The temperature of 1,3-propanediol when adding the titanium compound catalyst is in the range of -20 ° C to 30 ° C, more preferably in the range of 0 ° C to 10 ° C.

  The concentration of the catalyst with respect to 1,3-propanediol is preferably in the range of 0.03 to 1.0% by weight. By setting it as 0.03 weight% or more, the addition amount of the titanium compound catalyst used by transesterification can be increased, As a result, transesterification time can be shortened. Moreover, it becomes easy to suppress precipitation of a titanium compound catalyst by setting it as 1.0 weight% or less. As a result, it can be suppressed that it becomes a foreign substance in the obtained PTT. From the viewpoint of ensuring the reaction rate and suppressing precipitation, the concentration of the titanium compound catalyst relative to 1,3-propanediol is preferably in the range of 0.03 to 1.0% by weight. More preferably, it is 0.08 to 0.2% by weight.

  When mixing the titanium compound catalyst and 1,3-propanediol, the titanium compound catalyst may be added to 1,3-propanediol in a stirred state or in a fluidized state by piping or a static mixer. preferable. By doing in this way, precipitation of a titanium compound catalyst is suppressed. As a result, a decrease in the activity of the catalyst is suppressed or it is difficult to become a foreign substance.

Hereinafter, the polycondensation reaction for obtaining PTT using the oligomer of the present invention will be described in detail.
The lower alcohol ester of terephthalic acid obtained by transesterification and the oligomer obtained from 1,3-propanediol and / or its oligomer are reacted under high temperature and high vacuum. The reaction temperature is preferably 240 to 275 ° C. from the viewpoint of the reaction rate and the color tone of the polymer. In addition, it is preferable that the reaction pressure is reduced stepwise by using a plurality of reaction vessels. Ultimately, a high vacuum of 10 to 300 Pa is preferable because a reaction rate and a high degree of polymerization can be obtained. Further, if necessary, the titanium compound catalyst added by the transesterification reaction can be further added even at the stage of the polycondensation reaction. The amount is preferably 0.03 to 0.3% by weight as the total amount added in the transesterification reaction and polycondensation reaction with respect to the obtained PTT, from the viewpoint of reaction rate and color tone. . The PTT obtained by the polycondensation reaction is discharged in a strand form from the discharge portion of the polycondensation reaction tank, and can be obtained in the form of pellets after cooling with water or the like.

  In this invention, you may mix various additives other than an organic titanium compound catalyst as needed. For example, in order to improve the color tone, it is preferable to add a phosphorus compound at an arbitrary stage until the start of the polycondensation process. For example, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, phosphoric acid, phosphorous acid and the like are added, and the addition amount is 0.001 to PTT. Addition of 2% by weight, preferably 0.02-1% by weight, is preferable from the viewpoint of hue, heat resistance, and high-temperature coloring suppression. Moreover, as a coloring inhibitor, cobalt compounds, such as cobalt acetate and cobalt formate, and a commercially available fluorescent brightener may be added, and 0.0001 to 0.1% by weight of PTT is preferably added.

  Also, at any stage until the polycondensation process begins, matting agents such as titanium oxide, heat stabilizers, antifoaming agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent A brightener or the like may be copolymerized or mixed. In particular, when titanium oxide used as a matting agent is used, the average particle size is preferably 0.01 to 0.7 μm, and preferably 0.01 to 3% by weight per polymer weight.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, it cannot be overemphasized that this invention is not limited at all by an Example etc. The main measurement values in the examples were measured by the following methods.
(1) Intrinsic Viscosity This intrinsic viscosity [η] uses an Ostwald viscosity tube, and the ratio ηsp / C between the specific viscosity ηsp and the concentration C (g / 100 milliliters) is set to zero using 35 ° C. and o-chlorophenol. Extrapolated and determined according to the following formula:
[Η] = lim (ηsp / C)
C → 0
(2) Color tone evaluation of polymer Color measurement was performed using a fine PTT and a color computer of Suga Test Instruments Co., Ltd. b * indicates yellowishness and blueness. Yellowishness increases as the numerical value increases from 0, and conversely, when it becomes negative, blueness increases.

(3) Quantification of BHPE in PTT 2 g of refined PTT is added to 25 ml of a 2N potassium hydroxide methanol solution, and solvolysis is performed over 4 hours under reflux. BHPE in the methanol solution was quantified by gas chromatography. The gas chromatography column uses DURABOND DB-WA x 0.25 mm x 30 m (0.25 μm), and helium is measured as a carrier gas at a temperature of 20 ° C./min from 150 to 230 ° C. while flowing 100 ml / min of helium. did.

(4) Evaluation of ratio of hydroxyl terminal to all terminals, transesterification rate, cyclic oligomer concentration, average degree of polymerization PTT oligomer or PTT polymer is deuterated hexafluoroisopropanol / deuterated chloroform = 1/1 (volume ratio). And was measured under the following conditions by each magnetic resonance spectrum method. Moreover, when signal intensity required when calculating | requiring each evaluation value was set to AD, it computed from the integrated value of the following chemical shift ranges.
A = Signal intensity derived from benzene ring of main chain skeleton: 8.0 to 8.1 ppm
B = Signal intensity derived from a methylene group adjacent to the hydroxyl end: 3.83 to 3.87 ppm
C = Signal intensity derived from methyl group terminal: 3.9 to 4.0 ppm
D = Signal intensity derived from benzene ring of cyclic oligomer: 7.6 to 7.7 ppm
Calculation of the ratio of hydroxyl end to all ends

Since all carboxyl groups and allyl groups at the end are minute, it is assumed to be composed of two types of methyl group and hydroxyl group, and is calculated from the following formula.
Ratio of hydroxyl terminal to all terminals = (B / 2) / (B / 2 + C / 3) × 100 (%)
In addition, the transesterification rate is the same as the ratio of hydroxyl terminal to all terminals.
Cyclic oligomer concentration Cyclic oligomer concentration = D / A x 100 (%)
Average degree of polymerization Average degree of polymerization = 2 × (A / 4) / (B / 2 + C / 3)
Apparatus: FT-NMR DPX-400
Observation nucleus: 1H
Observation frequency: 400 MHz
Chemical shift reference value: Tetramethylsilane was 0 pppm.
Total number of times: 256 Waiting time: 3 seconds Solvent: Deuterated hexafluoroisopropanol / deuterated chloroform = 1/1 (volume ratio)
Sample concentration: 5% by weight
Measurement temperature: room temperature

[Example 1]
Dimethyl terephthalate (hereinafter abbreviated as DMT) was maintained at a temperature of 175 ° C., and was supplied in a molten state to the first reaction vessel in the transesterification step at a supply rate of 0.81 kg / min. Moreover, after putting 1,3-propanediol into a catalyst addition tank with a stirring blade cooled to 5 ° C., after confirming that the temperature of 1,3-propanediol reached 5 ° C., the stirring blade was set at 200 rpm. While rotating at the rotational speed, titanium butyl titanate was gradually added to prepare 1,3-propanediol containing 0.137 wt% titanium catalyst. The 1,3-propanediol was fed at a feed rate of 0.476 kg / min to the first reaction vessel in the vertical transesterification step with a stirring blade. At this time, the molar ratio of 1,3-propanediol to dimethyl terephthalate (hereinafter abbreviated as G value) was 1.5.

  The temperature of the reaction vessel in the first transesterification step was 180 ° C. and normal pressure, and the residence time in this reaction vessel was 1 hour 50 minutes. The rotation speed of the stirring blade was 200 rpm. At this time, methanol was distilled from the reaction vessel in the transesterification step at a rate of 0.210 kg / min. The reaction liquid such as an ester composed of dimethyl terephthalate and 1,3-propanediol and unreacted monomer discharged at a rate of about 1.08 kg / min from the discharge section of the reaction vessel in the first transesterification step continues. , And supplied to the reaction vessel of the second transesterification step of the same type as the first.

  The reaction temperature of the reaction vessel in the second transesterification step was set to 225 ° C. and the residence time was 1 hour. The amount of methanol distilled from the reaction vessel in the second transesterification step was 0.05 kg / min. Moreover, the pressure of the reaction tank of the 1st and 2nd transesterification process was performed at 101 kPa. The average degree of polymerization of the reaction product at the end of the second transesterification step was 2.2. Moreover, the ratio of the hydroxyl terminal with respect to all the terminals was 97 mol%, and the amount of cyclic oligomers was 1.5 weight%. Further, BHPE of the reaction product was 0.08% by weight.

  The reaction liquid discharged from the reaction vessel in the second transesterification step was continuously supplied to the reaction vessels in the first to third polycondensation steps. The first polycondensation reaction tank has a reaction temperature of 255 ° C., a pressure of 4 kPa, a residence time of 60 minutes, the rotation speed is 200 rpm, and the reaction tank of the second polycondensation step has a reaction temperature of 255 ° C., a pressure of 0.1 kPa, and a residence time of 60 minutes. The polycondensation reaction was carried out so that the rotational speed was 70 rpm, the reaction tank in the third polycondensation step had a reaction temperature of 258 ° C., a pressure of 0.07 kPa, and a residence time of 120 minutes. In the reaction tanks of the first and second polycondensation steps, a polycondensation reaction was performed using a vertical reaction tank in which a motor for driving the stirring blades is located above the reaction tank.

  Thereafter, the reaction tank in the third final polycondensation step was a horizontal reaction tank having a horizontal stirring axis, and the rotation speed was 8 rpm. PTT was discharged from the horizontal reaction tank at a rate of about 0.86 kg / min (about 1.24 t / day), cooled with 20 ° C. water, and a PTT having an average maximum length of 4 mm was obtained with a tip cutter. The intrinsic viscosity (hereinafter abbreviated as [η]) of the obtained PTT was 0.9 dl / g. Further, the by-product gas line of the transesterification reaction step and the polycondensation step was not clogged due to adhesion of low molecular weight compounds during the continuous reaction period of 30 days. The b * of the obtained PTT was 4.0, and BHPE was 0.3% by weight.

[Example 2]
The same procedure as in Example 1 was conducted except that the feed rate of 1,3-propanediol containing the catalyst was 0.413 kg / hr and the G value was 1.3. The total methanol distilled off from the first and second transesterification reaction tanks was 0.25 kg / hr. The average degree of polymerization of the reaction product at the end of the second transesterification step was 3.2. Moreover, the ratio of the hydroxyl terminal with respect to all the terminals was 94 mol%, and the amount of cyclic oligomers was 1.9 weight%. Further, BHPE of the reaction product was 0.06% by weight. [Η] of PTT of PTT obtained by the subsequent polycondensation reaction was 0.89 dl / g. Moreover, there was no obstruction | occlusion by a low molecular weight compound during the continuous reaction period of 30 days. The b * of the obtained PTT was 4.0, and BHPE was 0.25% by weight.

[Example 3]
In order to examine the influence of the temperature of the transesterification reaction, the same operation as in Example 1 was performed except that the reaction temperature of the first transesterification reaction tank was 195 ° C. and the reaction temperature of the second transesterification reaction tank was 230 ° C. It was. The average degree of polymerization of the reaction product at the end of the second transesterification step was 2.8. Moreover, the ratio of the hydroxyl terminal with respect to all the terminals was 98.9 mol%, and the amount of cyclic oligomers was 2.0 weight%. Further, BHPE of the reaction product was 0.09% by weight. [Η] of PTT of PTT obtained by the subsequent polycondensation reaction was 0.88 dl / g. Moreover, there was no obstruction | occlusion by a low molecular weight compound during the continuous reaction period of 30 days. The obtained PTT had b * of 5.0 and BHPE was 0.6% by weight.

[Example 4]
In order to examine the effect of the transesterification pressure, the same procedure as in Example 1 was performed except that the reaction pressure in the first transesterification reaction tank was 90 kPa. The average degree of polymerization of the reaction product at the end of the second transesterification step was 3.2. Moreover, the ratio of the hydroxyl terminal with respect to all the terminals was 95.0 mol%, and the amount of cyclic oligomers was 2.0 weight%. Further, BHPE of the reaction product was 0.05% by weight. [Η] of PTT of PTT obtained by the subsequent polycondensation reaction was 0.89 dl / g. Moreover, there was no obstruction | occlusion by a low molecular weight compound during the continuous reaction period of 30 days. The obtained PTT had b * of 5.0 and BHPE of 0.3% by weight.

[Comparative Example 1]
In order to examine the influence of the number of reaction vessels in the transesterification reaction, the same procedure as in Example 1 was carried out except that the number of transesterification reactions was 1, the reaction temperature was 240 ° C., and the residence time was 1 hour 30 minutes. . As a result, the transesterification rate after completion of the transesterification reaction was 89%, the average degree of polymerization was 1.8, and the cyclic oligomer was 0.9%. Further, BHPE was 0.05%. Thereafter, the polycondensation reaction was carried out in the same manner as in Example 1. As a result, [η] of the obtained PTT was 0.88 dl / g, b * was 4.2, and BHPE was 0.2% by weight. . Further, during the continuous reaction period, the by-product gas line was blocked due to the scattering of low molecular weight compounds on the 10th day, and the degree of vacuum deteriorated, so the operation was stopped.

[Comparative Example 2]
In order to examine the influence of the raw material composition, in order to reduce the molar ratio of 1,3-propanediol to DMT as 1.198, the feed rate of 1,3-propanediol containing the catalyst of Example 1 was set to 0.38 kg. / Min. As a result, the transesterification rate after completion of the transesterification reaction was 91%, the average degree of polymerization was 7.1, and the cyclic oligomer was 2.1% by weight. BHPE was 0.13%. Thereafter, polycondensation reaction was performed in the same manner as in Example 1. As a result, [η] of the obtained PTT was 0.87 dl / g, b * was 4, and BHPE was 0.19 wt%. Further, during the continuous reaction period, the by-product gas line was blocked due to the scattering of low molecular weight compounds on the 12th day, and the degree of vacuum deteriorated, so the operation was stopped.

[Comparative Example 3]
In order to examine the influence of the reaction temperature of the first transesterification reaction tank, the reaction was performed in the same manner as in Example 1 except that the reaction temperature of the first transesterification reaction tank of Example 1 was set to 205 ° C. As a result, the transesterification rate after completion of the transesterification reaction was 99%, the average degree of polymerization was 3.2, and the cyclic oligomer was 2.0%. Further, BHPE was 0.18%. Thereafter, the polycondensation reaction was performed in the same manner as in Example 1. As a result, [η] of the obtained PTT was 0.88 dl / g, b * was 5.8, and BHPE was as high as 0.8% by weight. Met. Moreover, there was no obstruction | occlusion by a low molecular weight compound during the continuous reaction period of 30 days.

[Comparative Example 4]
In order to see the influence of the reaction temperature of the final transesterification reaction tank, it was carried out in the same manner as in Example 1 except that the reaction temperature of the second transesterification reaction tank in Example 1 was changed to 195 ° C. As a result, the transesterification rate after completion of the transesterification reaction was 85%, the average degree of polymerization was 1.9, and the cyclic oligomer was 0.8%. The BHPE was 0.03%. Thereafter, the polycondensation reaction was carried out in the same manner as in Example 1. As a result, [η] of the obtained PTT was 0.85 dl / g, b * was 3.3, and BHPE was 0.11% by weight. . Further, during the continuous reaction period, the by-product gas line was blocked due to the scattering of low molecular weight compounds on the 9th day, and the degree of vacuum deteriorated, so the operation was stopped.

  A lower alcohol ester of terephthalic acid composed of a lower alcohol ester of terephthalic acid and 1,3-propanediol, an ester obtained from 1,3-propanediol and an oligomer thereof, and an unreacted lower alcohol ester of terephthalic acid and a cyclic oligomer Therefore, the frequency of blockage of the vacuum line in the subsequent polycondensation reaction is reduced. As a result, it becomes effective as a stable production technique in continuous polymerization. Moreover, since the obtained PTT is excellent in color tone and has few ether bonds as a by-product, a product having excellent thermal stability can be obtained.

Claims (5)

An ester obtained from a lower alcohol ester of terephthalic acid and 1,3-propanediol and / or an oligomer thereof satisfying the following requirements (1) to (5).
(1) The main repeating unit is composed of trimethylene terephthalate.
(2) The average degree of polymerization is in the range of 1.5-7.
(3) The cyclic oligomer is in the range of 0 to 2.2% by weight based on the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol.
(4) The range of 92-100 mol% of hydroxyl groups among all terminal groups of the ester and / or oligomer obtained from the lower alcohol ester of terephthalic acid and 1,3-propanediol.
(5) Bis (3-hydroxypropyl) ether is in the range of 0 to 0.3% by weight. In the transesterification reaction in which the lower alcohol ester of terephthalic acid and 1,3-propanediol are reacted in the presence of a titanium compound catalyst to form the ester and / or oligomer thereof according to claim 1, the following (1) to A continuous transesterification method characterized by satisfying the requirement of (6).
(1) The number of transesterification reaction tanks is in the range of 2-4.
(2) The molar ratio of 1,3-propanediol to the lower alcohol ester of terephthalic acid is in the range of 1.2 to 1.7.
(3) The reaction temperature of the first transesterification reaction tank is in the range of 170 ° C. to 200 ° C., and the transesterification rate of the reactant obtained from the reaction tank is in the range of 75 to 90%.
(4) The reaction temperature of the final transesterification reaction tank is in the range of 200 ° C to 235 ° C, and the transesterification rate of the reactant obtained from the reaction tank is in the range of 92 to 100%.
(5) The reaction pressure of all the transesterification reaction tanks is in the range of 80 kPa to 120 kPa.
(6) The addition amount of the titanium compound catalyst to the transesterification reaction tank is in the range of 30 to 150 ppm as a titanium element with respect to the lower alcohol ester of terephthalic acid. The continuous transesterification method according to claim 2, wherein the addition method of the titanium compound catalyst has the following requirements (1) to (4).
(1) A titanium compound catalyst and 1,3-propanediol are mixed before the transesterification reaction.
(2) The temperature of 1,3-propanediol when mixing the titanium compound catalyst is -20 ° C or higher and 30 ° C or lower.
(3) The concentration of the titanium compound catalyst with respect to 1,3-propanediol is in the range of 0.03 to 1% by weight.
(4) Mixing by adding a titanium compound catalyst to 1,3-propanediol in a fluid state. A process for producing polytrimethylene terephthalate, comprising subjecting a lower alcohol ester of terephthalic acid obtained in claim 2 or 3 and an ester and / or oligomer of 1,3-propanediol to a polycondensation reaction. Polytrimethylene terephthalate obtained from claim 4.