JPS62225524A - Production of polybutylene terephthalate polymer having high polymerization degree - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having excellent transparency in a short time, by carrying out the polycondensation of terephthalic acid with butanediol in the presence of a polyhydric alcohol using an organic titanium compound and a lithium compound as catalysts. CONSTITUTION:The objective polymer can be produced by the direct polycondensation of (A) a dicarboxylic acid component composed mainly of terephthalic acid and (B) a glycol component composed mainly of 1,4-butanediol in the presence of (C) 0.005-0.5wt% (based on the produced polymer) polyhydric alcohol of formula (R is methylol, etc.) (e.g. 1,1,1-trimethylolethane), (D) 0.005-0.5wt% organic titanium compound (e.g. methyl titanate, etc.) based on the produced polymer in terms of titanium atom and (E) 0.0002-0.3wt% lithium compound (e.g. lithium acetate) based on the produced polymer.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing a highly polymerized polybutylene terephthalate polymer (hereinafter referred to as PBT), and more specifically, a method for producing a highly polymerized polybutylene terephthalate polymer (hereinafter referred to as PBT), and more specifically, , 4-butanediol (hereinafter referred to as BG) as the main starting material (hereinafter referred to as direct polymerization method), the application of a new catalyst results in less turbidity, good transparency, and a high degree of polymerization. Regarding the manufacturing method of PBT.

[Prior art] Conventionally, in the production method of PBT, especially in the so-called direct loading method in which TPA and BG are esterified and then polymerized, BG is easily converted to tetrahydrofuran (hereinafter referred to as TI-IF), which is Not only is this a problem in terms of cost, but even the production conditions suitable for polyesters such as polyethylene terephthalate are not at all compatible with the esterification or polycondensation reaction of PBT.

Various proposals have been made to solve this problem with PBT, but most of them are based on organic titanium compounds (Japanese Unexamined Patent Publication No. 48-471) as catalysts for the esterification reaction between TPA and BG.
594) or a combination of an organic titanium compound and an organic tin compound (Japanese Patent Publication No. 55-300).
10) etc.

By the way, in the esterification reaction between TPA and BG, reaction water is produced, and since the reaction field is acidic, water is produced together with tetrahydrofuran by the dehydration cyclization reaction of BG. In such esterification reactions, organotitanium compounds represented by titanate esters exhibit excellent catalytic activity, but on the other hand, they have the essential drawbacks of being susceptible to hydrolysis and being easily deactivated. was.

For this reason, it is difficult for the organic titanium compound to maintain its excellent catalytic activity. Therefore, the amount of catalyst to be added should be increased in advance by taking into account the amount of deactivation during the reaction process, or Complicated measures such as adding a corresponding amount were required. An example of this is adding an organic titanium compound in portions to the first and second half of the esterification reaction (JP-A-49-57092).

By the way, today's production of PBH is economical.

In today's world where efficiency is strongly required, a highly active reaction catalyst has been desired due to the need to produce PBT with a high degree of polymerization in a shorter time than ever before. By increasing the amount of the organic titanium compound catalyst mentioned above, especially the titanate ester catalyst, it is possible to shorten the reaction time to some extent, but on the other hand, a new problem arises in that the resulting polymer becomes noticeably colored. Therefore, there is a limit to the amount of catalyst that can be increased. On the other hand, hydrolysis of organotitanium compound catalysts not only deactivates the catalytic ability, but also causes the resulting hydrolysis products to cloud the reaction system in an undissolved state, resulting in a significant decrease in the transparency of the resulting polymer. This will result in a loss.

Therefore, in order to produce PBT with good transparency and a high degree of polymerization in a short time by the direct loading method, it is necessary to deactivate the organic titanium compound catalyst by hydrolysis in the esterification reaction or polycondensation reaction. How to suppress this has been an important consideration in this technical field.

[Problems to be Solved by the Invention] An object of the present invention is to suppress deactivation due to hydrolysis of an organic titanium compound, particularly a titanate ester catalyst, in the production of PBT with a high degree of polymerization by a direct loading method. It is an object of the present invention to provide PBT with a high degree of polymerization which has excellent transparency and shortens the time required for the process. Another purpose is TPA containing an impurity amount of acetic acid.

Another object of the present invention is to provide an industrial method for producing highly polymerized PBH with excellent transparency using BG containing impurity amounts of acetic acid and/or its glycol ester as a raw material.

[Means for Solving the Problems] The above object of the present invention is to perform an esterification reaction and a polycondensation reaction from a dicarboxylic acid component mainly consisting of terephthalic acid and a glycol component mainly consisting of 1,4-butanediol. When producing PBT via this method, it can be achieved by using an organic titanium compound and a lithium compound as a reaction catalyst in the presence of a polyhydric alcohol represented by the following general formula (I).

(However, R is a hydrocarbon group or a methylol group.) Hereinafter, the structure of the present invention will be specifically explained. Below, the combined use of an organic titanium compound and a lithium compound as a reaction catalyst will be described.

That is, in the present invention, as a reaction catalyst.

First, an organic titanium compound is used, and the organic titanium compound particularly preferably used here is (R10). T!
(OR2> 4-0 [Here, R1 and R2 have a carbon number of 1 to
10 aliphatic, alicyclic, aromatic hydrocarbons, n is 1 to 3
numbers (including decimals). ] It is a titanate ester shown by. Specifically, titanic acid methyl ester, tetraisopropyl ester, tetraisopropyl ester, te-1-n-butyl ester, tetraisobutyl ester, tetra-tert-
These include butyl ester, cyclohexyl ester, phenyl ester, benzyl ester, tolyl ester, or a mixed ester thereof. Among these, tetra-n-propyl ester, tetraisopropyl ester, and tetraisobutyl ester are particularly preferably used.

Such an organic titanium compound is usually added in an amount of about 0.005 to 0.5% by weight, preferably 0.01 to 0.2% by weight, based on the titanium atomic weight of the produced polymer, before or at the initial stage of the esterification reaction. added. In addition, the organic titanium compound has an excellent catalytic effect not only on the esterification reaction but also on the polycondensation reaction, so that it can be used in the latter stage of the esterification reaction.

Alternatively, a method of additionally adding it before the beginning of the polycondensation reaction is preferably employed.

At this time, if the amount of the organic titanium compound added is less than 0.005% by weight, the effect as a catalyst for the esterification reaction or polycondensation reaction will be insufficient, and the esterification reaction time will be particularly long, and the THF (7) by-product will be The amount also increases. On the other hand, the amount added is 0
．． If it exceeds 5@m%, the catalytic effect will be saturated, and disadvantages such as warpage and decreased transparency of the polymer will occur, which is not preferable.

In addition, in order to further increase the esterification reactivity and suppress the by-product of THE, monoalkyltin compounds, monoaryltin compounds, dialkyltin compounds, diaryltin compounds, trialkyltin compounds, triaryltin compounds, tetra An organic tin compound such as an alkyltin compound can be used within a range of 0.05 to 2.0 as the molar ratio of tin atoms to titanium atoms in the organic titanium compound.

Next, the lithium compound to be used in combination with the organic titanium compound is preferably one that is soluble in the reaction system, such as lithium acetate or lithium oxalate.

Weak acid salts of lithium such as lithium citrate, lithium benzoate, lithium carbonate, lithium sulfate, lithium borate, lithium phosphate, lithium chloride.

Examples include inorganic acid salts such as lithium hydroxide, lithium alcolade, lithium fetchi-1, and the like.

Among these, particularly preferred are weak acid salts of lithium.

Such a lithium compound may coexist with the organic titanium compound particularly in the polycondensation reaction system, and therefore, it can be used simultaneously with the organic titanium compound or separately from before the esterification reaction to the initial stage of the polycondensation reaction. 0 for the generated polymer
．． 0002-0.3% by weight, preferably 0.001-0
．． It is added in an amount of 2% by weight, or so that the lithium atomic ratio to the titanium atoms of the organic titanium compound present in the polycondensation system is 0.1 or more.

At this time, the amount of lithium compound added was 0.002% by weight.
If it is less than 0.3% by weight, the desired improvement in polycondensation reactivity cannot be achieved; on the other hand, if it is added in excess of 0.3% by weight.

Not only does the catalytic action become saturated, but the thermal decomposition of the polymer tends to be accelerated, which is undesirable.

Next, in the present invention, a specific polyhydric alcohol must be used for the reaction catalyst, especially the organic titanium compound. That is, as mentioned above, the organic titanium compound has 2
Originally, when it comes into contact with water, it acts quickly and tends to become an insoluble substance (a substance that causes turbidity), but by having polyhydric alcohol present there, the catalytic activity of the organotitanium compound is not impaired.

Reduces the effect on water and insoluble substances (substances that cause turbidity)
In other words, the polyhydric alcohol acts to protect the titanium compound, which is weak against water, from water, and it is thought that the excellent catalytic activity inherent to the organic titanium compound can be maintained.

The polyhydric alcohol in this case is a polyhydric alcohol represented by the above formula (I>, specifically 1,1.1-
Examples include, but are not limited to, trimethylolethane, 1,1.1-trimethylolpropane, and pentaerythritol.

These polyhydric alcohols may be used alone or in combination of two or more, and may also be esterified.

The same type of polyhydric alcohol or different types of polyhydric alcohols may be used during the polycondensation reaction, and the polyhydric alcohol may also be added together with a suitable organic solvent such as BG.

The polyhydric alcohol usually has a concentration of 0°005 to the produced polymer.
It is added in an amount ranging from ~0.5% by weight, preferably from 0.01 to 0.2% by weight, and may be added all at once before the esterification reaction, or added in portions during the reaction. In order to obtain PBT with less turbidity, it is desirable to add polyhydric alcohol so that it is always present wherever the organic titanium compound is present in the reaction system.

Next, configurations of the present invention other than those described above will be described.

In the present invention, dicarboxylic acid is at least 50 mol% TPA, and the TPA includes not only ordinary so-called high-purity TPA but also acetic acid with impurities (approximately 0.3% by weight or less). Examples of dicarboxylic acids other than TPA include isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenylethanedicarboxylic acid, oxalic acid, 1,4-cyclohexane dicarboxylic acid, dodecane dicarboxylic acid, and adipine. Copolymerized components such as aromatic, aliphatic, and cycloaliphatic dicarboxylic acids such as acids can be used, but are not limited to less than 50 mole percent.

In addition, as a glycol component, at least 50 mol%
is necessary for BG, and examples of glycol components other than BG include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, 1,6-
Hexane glycol, cyclohexane 1,4-dimethynol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and modified products thereof can be used within 50 mol%.

In the esterification reaction using dicarboxylic acid and glycol as the main starting materials, the reaction conditions include the molar ratio of glycol to dicarboxylic acid used at the start of the reaction (
glycol/dicarboxylic acid) is preferably 1.8 or less, preferably 1.05 to 1.7. If it exceeds 1.8, a large amount of THF as a by-product due to the decomposition of BG will be produced, which will impair economic efficiency such as an increase in raw material cost 1-, which is not preferable.

In addition, at this time, the esterification reaction may be started by setting the molar ratio of glycol to dicarboxylic acid to 0.4 to 1.3, and then the remaining BG of the total required amount may be added to complete the esterification reaction. can.

Further, the temperature condition is preferably within the range of 180 to 240°C; particularly, if the temperature is too high, the decomposition of 8G becomes severe and the amount of THF by-produced increases, which is not preferable. Also, this temperature is maintained from the start of the esterification reaction until its completion.
The reaction may be carried out at a constant temperature, or the reaction temperature may be raised at any time from the start of the reaction.

Furthermore, the pressure conditions are usually 200 to 760 mm.
Although the reaction is carried out within the range of lIO, it is more effective to carry out the reaction under reduced pressure in order to suppress the decomposition of BG and the hydrolysis of the organic titanium compound. In addition, the reaction pressure at this time may be started from a weakly reduced pressure state, and a method may be adopted in which the degree of reduced pressure is increased from the middle of the reaction. The esterification reaction product obtained in this way is subsequently subjected to a polycondensation reaction, but the polycondensation reaction conditions are not particularly limited, and the reaction conditions used for the production of ordinary PBT can be adopted as they are. I can,
For example, under reduced pressure below immlq, temperature 230~2
For example, the reaction is carried out at 50°C.

In addition, various additives such as matting agents, optical brighteners, stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, crystal nucleating agents, etc. may be added to the extent that the original characteristics of PBT are not impaired. It may be added as appropriate.

[Effects of the Invention] As mentioned above, the present invention can be applied to the production of PBT using the direct loading method.
In particular, organic titanium compound catalysts have the contradictory characteristics of having poor hydrolysis resistance but excellent esterification reaction activity in the presence of specific polyhydric alcohols in reaction sites with a large amount of water. The gist of the invention is to use a lithium compound catalyst with remarkable polycondensation reaction activity, which results in extremely low turbidity, in other words, excellent transparency.
Moreover, PBT with a high degree of polymerization can be obtained in a short time.

Furthermore, even if TPA, which is the main raw material of PBT, contains acetic acid as an impurity, which promotes the hydrolysis of paid titanium compounds, it will degrade in the presence of specific polyhydric alcohols. with titanium compounds.

Highly polymerized PBT with excellent reaction activity and synergistic action with lithium compound catalysts, allowing smooth esterification and polycondensation reactions, significantly less turbidity, and good transparency.
is obtained.

The present invention will be specifically described below with reference to Examples.

In this example, 2 parts means parts by weight, and intrinsic viscosity was measured in orthochlorophenol at 25°C.

Rough solution haze is a mixture of phenol and tetrachloroethane (60
: 40wt%) Polymer chip 5.4 in mixed solvent 40d
g was dissolved by heating, and the polymer solution was placed in a 30IIII quartz cell and measured using an integrating sphere type haze meter (manufactured by Nippon Seimitsu Kogaku).

Examples 1 to 5, Comparative Examples 1 to 6 755 parts of TPA (containing acetic acid @0.02% by weight), BG6
96 parts, a polyhydric alcohol, a titanium compound, and a lithium compound shown in Table 1 are charged into a reactor equipped with a rectification column, and the temperature is gradually raised from 180°C to 230°C to undergo an esterification reaction to produce the product. The water and T I-IF were drained through a rectifier. After starting the esterification reaction,
The time required for the reaction to complete was 3.0 to 3.5 hours.

A part of the obtained reaction product was transferred to an autoclave, and the titanium compound and lithium compound shown in Table 1 were added thereto, and the pressure was gradually reduced from normal pressure to 1.0 mmf1g or less over 1 hour, and at the same time, the temperature was heated to 245°C. Increase the temperature to 245℃
A polycondensation reaction was carried out for 3.5 hours at 1mmt1g or less.

Table 1 shows the amount of by-product THF, degree of polymerization (intrinsic viscosity) and transparency (solution haze) of the obtained polymer in this case.

As is clear from these results, the synergistic effect of the polyhydric alcohol, titanium compound, and lithium compound in the present invention is significantly recognized regarding the degree of polymerization and transparency of the polymer.

Examples 6-10, Comparative Examples 7-12 755 parts of TPA, 348 parts of BG, shown in Table 2.

A polyhydric alcohol, a titanium compound, a lithium compound, and 0.05% by weight (based on the polymer) of monobutyltin oxide (monobutyl hydroxytin oxide in Examples 9 and 10) were added to a reactor equipped with a rectification column. The esterification reaction was started at 180° C. and a reduced pressure of 500 mmHg, and while the temperature was gradually raised, 186 parts of BG was continuously added. The produced water and THF were drained through a rectification column.

The time required from the start of the esterification reaction to the completion of the reaction was 3.0 to 3.5 hours (temperature at the completion of the esterification reaction: 240°C).

A part of the obtained reaction product was transferred to an autoclave, and a polyhydric alcohol, a titanium compound, a lithium compound, and 0.02% (based on polymer) phosphorous acid as shown in Table 2 were added, and the reaction was carried out. A polycondensation reaction was carried out in the same manner as in Example 1.

Table 2 shows the by-product T+-(Fffi), the polymerization degree (intrinsic viscosity) and transparency (solution haze) of the obtained polymer in this case.

(Hereafter, margin)

Claims (1)

[Claims] (1) A dicarboxylic acid component mainly consisting of terephthalic acid, and 1
When producing polybutylene terephthalate from a glycol component mainly containing , 4-butanediol through an esterification reaction and a polycondensation reaction, the following general formula (I
) A method for producing a highly polymerized polybutylene terephthalate polymer with good transparency, characterized by using an organic titanium compound and a lithium compound as a reaction catalyst in the presence of a polyhydric alcohol represented by (a). (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R is a hydrocarbon group or a methylol group.)