JPH0739481B2 - Method for producing polybutylene terephthalate polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing polybutylene terephthalate (hereinafter referred to as PBT), and more specifically to terephthalic acid (hereinafter referred to as “PBT”).
TPA) and 1,4-butanediol (hereinafter referred to as BG)
In the direct polymerization method (hereinafter referred to as the direct weight method) with and, it relates to a method for producing a PBT with less turbidity by applying a new catalyst.

[Prior Art] Generally, as a method for producing PBT, as in the case of polyethylene terephthalate (hereinafter referred to as PET), a polymerization method via an ester exchange reaction between an alkyl ester of TPA, particularly dimethyl terephthalate and BG, and TPA and BG. It is known that the so-called direct weight method, in which after the esterification with
In the former, there is a decrease in economic efficiency due to the bypass of the process, while in the latter, BG is easily converted to tetrahydrofuran, and even under suitable manufacturing conditions as PET, it is not suitable for the esterification or polycondensation reaction of PBT at all. there were.

A number of proposals have been made to date for the problem of PBT. Most of them are organic titanium compounds (JP-A-48-4794), organic tin compounds (JP-B-55-34829) as esterification reaction catalysts of TPA and BG,
Alternatively, it was a combination of an organic titanium compound and an organic tin compound (Japanese Patent Publication No. 55-3010).

However, in the direct esterification reaction by the reaction between TPA and BG, water of reaction is produced, and since the reaction field is acidic, water is produced together with tetrahydrofuran (hereinafter referred to as THF) by the dehydration cyclization reaction of BG.

Organic titanium compounds represented by titanic acid esters have excellent catalytic activity for the esterification reaction, but
Since it has an essential drawback that it is easily hydrolyzed by water and easily deactivated, the catalyst activity cannot be maintained in the above-mentioned reaction field, and not only the esterification reaction but also the subsequent In the polycondensation reaction process to be performed, a complicated means such as supplementing a catalyst commensurate with the deactivated content is newly required. An example thereof is addition of an organic titanium compound in the first half and the second half of the esterification reaction (JP-A-49-57092).

The catalyst residue hydrolyzed and deactivated by the water produced by the titanate ester catalyst in the esterification reaction or polycondensation reaction process becomes insoluble in the esterification product or the polymer, This may cause deterioration of transparency and deterioration of solution haze in the case of a polymer in a solution state. The insoluble matter in such a polymer sometimes becomes a foreign matter, and when it is remarkable, it has a problem that it causes unevenness in strength or a decrease in strength of a molded product or a yarn.

Here, the problem of a known titanate ester as an esterification reaction catalyst of TPA and BG, for example, a tetraalkyl titanate represented by Ti (OR) ₄ (where R is an alkyl group) will be specifically explained. The esterification reaction between BG and BG, as shown in the above-mentioned JP-A-48-47594,
Although BG / TPA (molar ratio) can be carried out at 1.2 to 3.0, actually, when the tetraalkyl titanate catalyst is used, the esterification reaction rate is large when BG / TPA (molar ratio) is large, and Although the transparency of the obtained polymer is also excellent, the production of by-product THF due to the decomposition of BG is significantly increased. On the other hand, when BG / TPA (molar ratio) is small, the esterification reactivity deteriorates. Moreover, the transparency of the polymer is also reduced, and particularly when the BG / TPA (molar ratio) is 1.8 or less, the transparency is remarkably reduced.

As a method of producing TPA, which is one raw material of the direct weight method, various economically advantageous methods have been proposed. In recent years, most of them have been produced by a method based on air oxidation of p-xylene. Since TPA contains acetic acid that is mixed in during the manufacturing process, it is sufficiently purified, but usually about 0.003 to 0.3% by weight of acetic acid remains after the purification.

On the other hand, PBT has a concentration of 1.2 to 3.
BHBT obtained by esterification using BG in an excess amount of 0 mol and an organotitanium compound as a catalyst at high temperature,
It is produced by a method of polycondensation under high vacuum. Here from an economic point of view, BG used in excess in the esterification process
Is usually distilled and recovered by a polycondensation reaction. Therefore, it is of great industrial or commercial significance to recycle the recovered BG as a part of the raw material for manufacturing PBT.

However, when TPA containing acetic acid is used in this esterification step, acetic acid easily reacts with BG to form B.
It is converted to G monoacetate and a small amount of diacetate compound, a glycol ester of acetic acid. Since the boiling points of this glycol ester of acetic acid and BG are extremely close to each other, it is not possible to easily separate them in the recovery of BG. Therefore, if the recovered BG is used as a raw material as it is, acetic acid and / or a glycol ester component of acetic acid naturally accumulate in the recovered BG.

When BG containing such acetic acid and its glycol ester is fed to the esterification as a raw material, the esterification and the subsequent polycondensation reaction are significantly delayed, and in extreme cases, the esterification reaction may not be completed. It has been found that not only significantly impairs the economics of PBT manufacturing, but also reduces the quality of the polymer. Although the reason for the delayed phenomenon of the esterification reaction is not clear, the titanium-based compounds that are effective and widely used as catalysts for the PBT synthesis reaction are not hydrolyzed by water themselves in the presence of acetic acid and the like. It is considered that the main cause is that the catalyst activity is accelerated and the catalytic activity is deactivated.

[Problems to be Solved by the Invention] An object of the present invention is to provide an industrial production method of high-quality PBT with less turbidity, from a dicarboxylic acid mainly containing TPA and a glycol mainly containing BG. Still another object is to provide an industrial production method of PBT with less turbidity, using TPA containing acetic acid and BG containing acetic acid and / or its glycol ester as raw materials.

[Means for Solving Problems] The above object of the present invention is to provide polybutylene from a dicarboxylic acid component mainly containing TPA and a glycol component mainly containing BG via an esterification reaction and a polycondensation reaction. In the production of terephthalate, a titanic acid ester represented by the following general formula (I) and an alkanolamine represented by the general formula (II) are added in an esterification reaction step of a polybutylene terephthalate polymer. Manufacturing method.

(R ₁ O) nTi (OR ₂ ) _4- n (I) Here, R ₁ and R ₂ are aliphatic, alicyclic or aromatic hydrocarbons having 1 to 10 carbon atoms, and n is 1 to 3 Is the number of (including decimals).

Here, L ₁ , L ₂ and L ₃ are hydrogen atoms, alkyl groups, allyl groups,
Alternatively, it represents -X-OH, and at least one of L _{1 to} L ₃ is -X-OH, and X is a C _{1 to} C ₆ aliphatic hydrocarbon residue.

Can be achieved by

The configuration of the present invention will be specifically described below.

As the dicarboxylic acid in the present invention, at least 50 mol% is TPA.
Those containing 3% by weight or less and 0.01% by weight or more of acetic acid are also used. Examples of the dicarboxylic acid other than TPA include isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylethanedicarboxylic acid, diphenyletherdicarboxylic acid, sebacic acid, oxalic acid, 1,4-cyclohexanedicarboxylic acid, dodecanedioic acid and adipic acid. The copolymerization component such as aromatic, aliphatic or alicyclic dicarboxylic acid can be used in an amount of less than 50 mol%, but is not limited thereto.

Further, as a glycol component, at least 50 mol%
BG, as the glycol component other than BG, for example, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, 1,6-hexane glycol, cyclohexane 1,4-dimethynol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, And these modified products and the like can be used within 50 mol%.

The molar ratio of these BG-based glycol components to TPA-based dicarboxylic acid components is 1.8 or less, preferably 1.05 to 1.7. If it exceeds 1.8, a large amount of THF is produced as a by-product due to the decomposition of BG, which lowers the cost of raw materials and impairs the economical efficiency, which is not preferable.

The esterification or polycondensation reaction catalyst in the present invention is a titanic acid ester represented by the above formula (I), and specifically, methyl ester of titanic acid, tetra-n-propyl ester, tetraisopropyl ester, tetra-n.
-Butyl ester, tetraisobutyl ester, tetra-tert-butyl ester, cyclohexyl ester, phenyl ester, benzyl ester, tolyl ester,
Alternatively, they are mixed alkyl esters of these. Of these, tetra-n-propyl ester, tetraisopropyl ester, and tetra-n-butyl ester are particularly preferable.

These titanic acid esters may be used alone or in combination of two or more, and the same or different organic titanium compounds may be used at the time of esterification and polycondensation reaction. It may be added together with the organic solvent. The organic solvent in this case is usually ethanol, isopropanol, n-propanol, n-butanol, i-butanol, 2-ethylhexanol,
Ethylene glycol, BG, etc. are used.

Further, the addition amount of the titanic acid ester is usually 0.005 to 0.5% by weight, preferably 0.01 to 0, with respect to the finally obtained polymer.
2% by weight.

Further, the titanate ester may be added all at once before the esterification reaction or in portions during the reaction.

General formula (II) used in combination with such titanate ester
Examples of the alkanolamine represented by are: monoethanol, diethanolamine, triethanolamine,
2-methylaminoethanol, 2-ethylaminoethanol, 2-butylaminoethanol, 2-dimethylaminoethanol, 2-diethylaminoethanol, 2-dibutylaminoethanol, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, Examples include aminopropanol, dimethylaminopropanol, 2-aminobutanol, diethylaminopentyne, -2-ol-4, triisopropanolamine, 2-amino-2-methylpropanol, dicyclohexylaminopropanol and diphenylaminoethanol. Of these, those mainly containing aliphatic alkanolamines are preferable, and diethanolamine, triethanolamine, N-methyl-diethanolamine and the like are particularly preferable.

These alkanolamines may be used alone or in combination of two or more, and the same or different alkanolamines may be used at the time of esterification and polycondensation reaction. It may be added together with the organic solvent.

The amount of the alkanolamine added is usually 0.005 to 0.5% by weight, preferably 0.01 to 0.2, based on the finally obtained polymer.
% By weight.

The alkanolamine may be added all at once before the esterification reaction or in divided additions during the reaction, but in order to obtain PBT with less turbidity, it is represented by the above formula (I) in the reaction system. When the titanic acid ester is present, it is necessary to consider the timing of addition so that a considerable amount of the alkanolamine represented by the general formula (II) is always present.

Here, if desired, a known reaction catalyst may be used in combination with the titanic acid ester represented by the formula (I) and the alkanolamine represented by the general formula (II).
In particular, in the present invention, the titanic acid ester added at the time of esterification includes an organic tin compound, for example, (R is an alkyl or aryl group, X ₁ is a monovalent group selected from the group consisting of alkyl, aryl, acyloxy, cycloalkyl, hydroxy, halogen, and X ₂
When used in combination with a tin compound represented by oxygen or sulfur), the polymer transparency effect is more excellent, and the generation of THF due to the decomposition of BG is significantly suppressed. At this time, the ratio of the titanium compound and the tin compound in the present invention is Sn / Ti (atomic ratio) of 0.05.
It is particularly effective in the range of up to 2.0. The clarification effect of the polymer possessed by the tin compound is explained as a result of suppressing the conversion of BG to THF and decreasing the production of water.

In carrying out the present invention, the esterification reaction temperature is 180-240.
The temperature is preferably in the range of 0 ° C., and may be maintained at a constant temperature from the start of the esterification reaction to the completion of the reaction, or the reaction temperature may be raised after the reaction is started. Good.

Here, the completion of the esterification reaction means the time when the esterification reaction rate reaches about 95% or more.

The esterification reaction pressure is usually in the range of 200 to 760 mmHg, but it is more effective to carry out the esterification reaction under reduced pressure in order to suppress the decomposition of BG.

For the same purpose, 0.4 to 1.3 mol of BG was added to 1 mol of the dicarboxylic acid mainly containing TPA to start the esterification reaction, and then the required amount of BG was additionally added to carry out the esterification reaction. It may be completed and then polycondensed.

In this case, it is usual to use a method in which the reaction pressure is started from a weak depressurized state and the degree of depressurization is increased during the reaction.

The esterification reaction product continues to undergo a polycondensation reaction,
For this method, the polycondensation conditions used for the production of ordinary PBT may be applied as they are. Therefore, in this case, other polycondensation catalysts, matting agents, optical brighteners, stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, crystal nucleating agents, etc. can be added as required. Is.

EFFECTS OF THE INVENTION The present invention provides a method in which the titanic acid is used in a system having the contradictory effects of hydrolysis resistance and esterification reaction activity in the presence of a large amount of water, such as in the production of direct weight PBT. The combined use of an ester and an alkanolamine can give PBT having a remarkably small turbidity in a relatively small range of a BG / TPA molar ratio of 1.8 or less. Even when TPA, which is the main raw material of PBT, contains acetic acid that accelerates the hydrolysis of the titanium compound, the esterification and polycondensation reaction can be performed by the combined use of the titanate ester and the alkanolamine as in the present invention. Can be performed smoothly, and PBT with extremely low turbidity can be provided.

The effect of the present invention is that the titanic acid ester represented by the above (I) is originally likely to act promptly upon contact with water to become an insoluble matter (substance causing turbidity). By adding it, the effect on water is mitigated and the insoluble matter (turbidity-causing substance) is less likely to be generated without impairing the original reaction activity of the titanate ester.
That is, it is considered to play a role of protecting the titanium compound, which is weak against water, from water. As a result, it is possible to obtain a PBT-based polymer having excellent transparency without lowering the original excellent reaction activity of the titanate ester.

Hereinafter, the present invention will be described with reference to examples.

In this example, “parts” means “parts by weight”, “intrinsic viscosity” means a value measured at 25 ° C. in orthochlorophenol, and “solution haze” means a polymer chip in 40 ml of a mixed solvent of phenol and ethane tetrachloride (60:40 wt%). 5 g of the polymer solution was heated and dissolved, and the polymer solution was placed in a 30 mm quartz cell and measured with an integrating sphere type haze meter (manufactured by Nippon Seimitsu Optical Co., Ltd.).

Example 1 755 parts of TPA containing 0.08% by weight of acetic acid, 696 parts of BG (BG / TP
A molar ratio 1.7) and tetra-n-butyl titanate 0.50
Parts and 0.50 parts of diethanolamine were charged into a reactor equipped with a rectification column, the esterification reaction was started at 180 ° C. under normal pressure, the temperature was gradually raised, and finally 230 ° C. was reached. The reaction was completed 3 hours and 25 minutes after the start of the esterification reaction. The amount of by-product THF at this time was 94 parts. A part of the obtained reaction product was transferred to an autoclave, and the titanium compound was further added with 0.05 part and diethanol 0.05 parts per 100 parts of the produced polymer.
Then, 5 parts and 5 parts were additionally added, the pressure was gradually reduced at 245 ° C., and the polycondensation reaction was performed at 1 mmHg or less. Intrinsic viscosity is 0 after 3 hours and 35 minutes.
A polymer having an excellent melt transparency of 90 was obtained. The solution haze of the polymer was 0.2%.

Comparative Example 1 In Example 1, 0.5 parts each of tetra-n-butyl titanate was added as an esterification or polycondensation reaction catalyst,
As a result of carrying out the reaction, the reaction was completed with esterification time of 3 hours and 45 minutes, accompanied by by-product THF of 95 parts. The polycondensation time was 3 hours and 50 minutes. The transparency of the produced polymer when melted was slightly poor, and the solution haze of the polymer was 8% and the intrinsic viscosity was 0.90.

Example 2 529 parts of TPA (acetic acid content of 0.02 wt%), isophthalic acid (IP
A) (acetic acid content 0.03 wt%) 226 parts and BG327 parts [BG /
(TPA + IPA) molar ratio 0.8] and tetra-n as catalyst
-Butyl titanate 0.50 parts, triethanolamine 0.50
Part, and 0.50 part of monobutyltin hydroxide were charged into a reactor equipped with a rectification column, and an esterification reaction was started at 180 ° C under a reduced pressure of 500 mmHg, and the temperature was gradually raised and 164 parts of BG (BG / dibasic base). An acid molar ratio of 0.4) was continuously added. 3 hours and 24 minutes after the start of the esterification reaction (at this time, the temperature is 240
The reaction was completed after (.degree. C.). The reaction rate at this time was 98.4%. A part of the obtained reaction product was transferred to an autoclave, 0.05 part of the titanium compound was further added to 100 parts of the produced polymer, and 0.02 part of phosphorous acid was added, and the pressure was gradually reduced at 245 ° C. and the weight was reduced to 1 mmHg or less. A condensation reaction was performed. 3 hours 2
After 0 minutes, a polymer having an intrinsic viscosity of 0.91 and excellent melt transparency was obtained. The solution haze of the polymer was 0.6%.

Comparative Example 2 In Example 2, the esterification or polycondensation reaction was carried out without addition of triethanolamine. As a result, the esterification time was 3 hours and 40 minutes, the polycondensation time was 3 hours and 45 minutes, and the intrinsic viscosity was 0.
90 polymers were obtained. The polymer in the molten state was slightly cloudy and the solution haze was 12%.

Example 3 TPA (acetic acid content 0.15 wt%) 755 parts, BG 614 parts (BG / TPA molar ratio 1.5), tetra-n-butyl titanate 0.90 parts, triethanolamine 0.90 parts, and monobutylhydroxytin oxide 0.6 parts. The mixture was charged into a reactor equipped with a rectification column and the esterification reaction was carried out in the same manner as in Example 1. The reaction was completed 3 hours and 15 minutes after the start of the esterification reaction. A part of the obtained reaction product was transferred to an autoclave, and 0.05 part each of the titanium compound and alkanolamine and 0.01 part phosphoric acid were added to 100 parts of the produced polymer.
The polycondensation reaction was carried out in the same manner as in. After 3 hours and 27 minutes, a polymer having an intrinsic viscosity of 0.91 and excellent melt transparency was obtained. The solution haze of the polymer was 0.5%.

Comparative Example 3 As a result of carrying out the esterification or polycondensation reaction in Example 3 without adding triethanolamine, the esterification reaction was completed 4 hours and 15 minutes after the start of the reaction. A part of the product was transferred to an autoclave, and 0.05 parts of tetra-n-butyl titanate and phosphoric acid were added to 100 parts of the produced polymer, respectively.
And 0.01 part were added and the polycondensation reaction was carried out in the same manner as in Example 3. After 4 hours and 5 minutes, a polymer having an intrinsic viscosity of 0.90 was obtained. The solution haze of the polymer was 14%.

Example 4 1132 parts of TPA (acetic acid content of 0.15 wt%), polycondensation distillate obtained in Example 3 (BG 86.1%, ester of acetic acid and BG 1.6)
%, Water 6.3% and THF 5.9%) 175 parts and
To 840 parts of BG, 1.40 parts of tetra-n-butyl titanate, 1.40 parts of triethanolamine, and 0.90 parts of monobutylhydroxytin oxide were charged in a reactor equipped with a rectification column, and esterification was carried out under the same conditions as in Example 3, Subsequently, the polycondensation reaction was carried out under the same conditions as in Example 3.

In this way, the reaction of circulating and reusing the BG distilled from the polycondensation reaction step was repeated 10 times, and the composition of the polycondensation distillate was BG 71%, BG ester of acetic acid 14%, water 9% and THF became 6%. 165 parts of this distillate was mixed with 780 parts of BG and used as the BG component for esterification. The esterification was performed for 3 hours and 30 minutes (esterification reaction rate 98.3%) and polycondensation for 3 hours and 30 minutes to obtain a unique property. Viscosity 0.91, polymer solution haze
0.8% polymer was obtained. In this case, the amount of acetic acid and its glycol ester present in the esterification reaction system was 1.05% by weight in terms of acetic acid (vs. TPA).

Comparative Example 4 In Example 4, the esterification or polycondensation reaction was repeated 10 times in the same manner as in Example 4 except that triethanolamine was not added, and the distillate from the polycondensation reaction was repeatedly used. Viscosity 0.90 (Polymer solution haze 0.8
%) Was required for 4 hours and 25 minutes of esterification (esterification reaction rate 98.0%) and 4 hours and 35 minutes of polycondensation time. In that case, the amount of acetic acid and its glycol ester present in the esterification reaction system is 1.09 in terms of acetic acid.
The polymer solution haze was 16% by weight (vs. TPA).

Claims (5)

[Claims] 1. When producing polybutylene terephthalate from an esterification reaction and a polycondensation reaction from a dicarboxylic acid component mainly containing terephthalic acid and a glycol component mainly containing 1,4-butanediol, A method for producing a polybutylene terephthalate polymer, which comprises adding a titanate represented by the following general formula (I) and an alkanolamine represented by the general formula (II) in an esterification reaction step. (R ₁ O) nTi (OR ₂ ) _4- n (I) where R ₁ and R ₂ are aliphatic, alicyclic or aromatic hydrocarbons having 1 to 10 carbon atoms, and n is 1 to 3 Is the number of (including decimals) Here, L ₁ , L ₂ , and L ₃ represent a hydrogen atom, an alkyl group, an allyl group, or —X—OH, at least one of L _{1 to} L ₃ is —X—OH, and X is C. an aliphatic hydrocarbon residue of ₁ -C _6. 2. A process for producing a polybutylene terephthalate polymer according to claim (1), wherein the alkanolamine is an alkanolamine represented by the following general formula (III). Here, L ₁ , L ₂ , and L ₃ represent a hydrogen atom, an alkyl group, an allyl group, or —CH ₂ CH ₂ —OH, and at least one of L _{1 to} L ₃ is —CH ₂ CH ₂ —OH. Is. 3. A polybutylene terephthalate polymer according to claims (1) and (2), wherein the titanate ester and the alkanolamine are each added in an amount of 0.005 to 0.5% by weight based on the produced polymer. Manufacturing method. 4. A method for producing a polybutylene terephthalate polymer according to claims (1) and (2), wherein the terephthalic acid contains acetic acid in an amount of about 0.3 or less by weight. 5. The dicarboxylic acid component mainly comprising terephthalic acid according to claims (1) to (3),
The esterification reaction system with glycol mainly consisting of 4-butanediol contains about 0.01 to 10% by weight of acetic acid and its glycol ester derived from impurities in terephthalic acid per dicarboxylic acid unit weight in terms of acetic acid. How to make a coalesce.