JPS61255928A - Production of polyester of high degree of polymerization - Google Patents

Abstract

PURPOSE:To obtain the titled quality polyester inexpensively in good efficiency, by using a thin-film polymerization tank as the last-stage reaction tank in a continuous melt polymerization process and operating this tank in conditions in which a specified relationship between the average residence time and the internal reaction temperature holds. CONSTITUTION:Terephthalic acid (dialkyl ester) and ethylene glycol are converted into a polyester monomer and/or prepolymer in an esterification tank or transesterification tank and then converted into a polymer of an intermediate MW corresponding to an intrinsic viscosity of 0.3-0.7 in the initial and intermediate polymerization tanks. This polymer is polymerized in a thin-film polymerization tank in which the polymer fed from a sparger 15 in the peripheral direction is formed into a film by rotating impellers 14 arranged concentrically in the direction of the periphery of a reaction tank 13 in conditions in which the average resisdence time theta(min) and the internal reaction temperature T( deg.C) can satisfy the relationship (wherein 280<=T) to obtain the titled polyester of an intrinsic viscosity >=0.8 and a carboxyl end group content <=20 equivalent/ T. This polyester is solidified by cooling, comminuted by means of a cutter and used as, e.g., a fiber for clothing and industrial materials.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a method for producing a polyester with a high degree of polymerization, and a method for producing an aromatic polyester with a high degree of polymerization by a melt polymerization method instead of using the conventional solid phase polymerization method. be.

PRIOR ART Polyester obtained from an aromatic difunctional carboxylic acid component and a glycol component is used for a variety of purposes due to its many excellent properties, especially in fibers, films, and molded products, such as strength and heat resistance. This increases its commercial value, but when it is used for materials that require durability, as well as for industrial fibers, especially tire cords and molded products, especially engineering plastics, it has even higher strength.
Hydrolysis resistance, etc. is required.

By the way, in order to improve the strength of polyester, it is effective to further increase the polymerization degree of K, and to improve the water decomposition resistance, it is effective to reduce the content of terminal carboxyl groups. It is generally well known that the isophase polymerization method is suitable as a method for this purpose.

That is, in solid phase polymerization, a medium molecular weight polymer obtained by ordinary melt polymerization is cooled and solidified, and then finely sized to an appropriate size, and then the particles are heated at a temperature of 5 to 60 degrees Celsius below the melting point under vacuum or under vacuum. This is a method of increasing the degree of polymerization of the polymer by flowing an inert gas, and since the temperature is lower than in the melt polymerization method, there are fewer reactions such as thermal decomposition reactions, and it is possible to obtain polyester with a high degree of polymerization and fewer terminal carboxyl groups. can.

However, since the temperature in such solid phase polymerization is about 25 to 95° C. lower than that in melt polymerization, the polymerization rate is extremely slow, which poses a serious problem in industrial production.

In addition, in the case of the solid phase polymerization method, a medium molecular weight polymer obtained by ordinary melt polymerization is cooled and solidified, and then pulverized into #1 particles of an appropriate size. Due to the energy loss and labor required due to transit, there was also a serious hindrance to industrial production.

On the other hand, there have been attempts to obtain polyesters with a high degree of polymerization by melt polymerization instead of in-phase polymerization. However, depending on the melt polymerization method, the decomposition reaction of polyester becomes noticeable, especially in the high polymerization degree range, and as a result, the solid viscosity does not increase, and the concentration of carboxyl terminals in the polymer increases, resulting in Physical properties are impaired.

Purpose and Structure of the Invention The present invention has been made against the background of the above circumstances.
The objective is to obtain a high reaction rate while suppressing decomposition using a thin film polymerization tank, and to produce a high-polymerization degree polyester of good quality efficiently and inexpensively by a melt polymerization method.

The present inventors have arrived at the present invention as a result of intensive research into a method for producing a high degree of polymerization polyester by a polyester melt polymerization method, which has a fast rate of success.

That is, the present invention uses a thin film polymerization tank as the Mth stage reaction tank to produce a high polymerization degree polyester by a continuous melt polymerization method, and the average residence time of the thin film polymerization tank (
This is a method for producing a highly polymerized polyester, which is characterized in that the operation is performed so that υ and reaction internal temperature (T° C.) satisfy the following relational expression.

0≦480-1,5T However, 280≦T In the present invention, the high polymerization degree polyester is an ester of terephthalic acid or terephthalic acid dialkyl ester (the number of carbon atoms in the alkyl group is usually 1 to 41 it) and ethylene glycol. The main target is polyethylene/dene 7 polymers obtained by esterification or transesterification and polycondensation reactions, but terephthalic acid or a portion of terephthalic acid dialkyl ester (usually 20 mol or less), such as Inphthal #! , phthalic acid, aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sepa-17 acid, and alkyl esters such as oxycarbo/acids such as 4-(β-oxydiethoxy)benzoic acid. Alternatively, part or all of ethylene glycol may be replaced with a glycol represented by HO(CH*)nOH (n is 3 to 10), such as propylene glycol or tetramethylene glycol.

In the present invention, manganese compounds, zinc compounds, magnesium compounds, etc. are used as transesterification catalysts, but as long as they have transesterification ability, they must be particularly limited! For example, halides, inorganic compounds such as #1 compounds, and organic acid salts are preferred, and organic acid salts such as acetates, propionates, salicylates, and benzoates are particularly preferred.

Hereinafter, the present invention will be explained in more detail based on the drawings. 1st
The figure shows a schematic process diagram for carrying out the present invention. In the figure, del/7 talic acid or terephthalic acid difurkyl ester and ethylene glycol are converted into l-& raw material polyester in an esterification tank or transesterification tank 1. A monomer and/or a low polymer thereof is produced.

This polymerization raw material is used in an initial polymerization tank 2 and a middle polymerization tank 3 to produce a polymer having a medium molecular weight according to a conventional method. The intrinsic viscosity of the polymer at this stage is 0.3 to 0.7.

In the method of the present invention, a thin film polymerization tank 4 is then used as the final stage reaction tank to directly produce a polymer having an intrinsic viscosity of 0.8 or more as it is by melt polymerization. After the produced polymer is cooled and solidified, it is finely granulated into appropriate sizes by a cutting machine 5 and used for clothing, industrial fibers, etc., or it is sent to a spinning device 6 without being granulated and directly spun. and used for the above purposes.

In addition, in the conventional method, the polymer that has passed through the initial polymerization tank 2 and the intermediate polymerization tank 3 ft is once granulated and then transferred to the solid phase polymerization reaction tank, where it remains finely granulated at 0.001 gap.
The solid phase polymerization reaction is carried out under ~10'm'H9(1)X9 and/or under nitrogen gas flow.

Here, in the present invention, it is necessary to use a thin film type polymerization tank as the final stage reaction tank, and several types of schematic diagrams are shown in FIGS. 2 to 5 as specific examples thereof. The second figure is a paddle! 11
2. Flow the polymer down to form a thin film! ? FIG. 3 shows a reaction tank 130 in which stirring blades 14 are arranged concentrically in the circumferential direction, and by rotating the stirring blades 14, the polymer is supplied in the circumferential direction from the polymer distribution device 15. This is an example of an apparatus for forming a polymer into a thin film. FIG. 4 shows that at least one cylindrical body 18 that moves along the circumferential direction in contact with or in close proximity to the tank wall 17 of the reaction tank 16 is moved in a planetary motion to form a thin film of polymer on the tank wall 17. FIG. 5 shows a modification of the thin film method in which the polymer is dropped as a large number of thin strand-like filaments 21 from the discharge nozzle 20 arranged at the upper part of the reaction tank 19, increasing the surface area by 7. This is an example of an apparatus that provides the same effect as when forming a thin film. Among these devices, it is preferable to use the device shown in FIG. 3, particularly FIG. 4, which is effective.

The characteristics of these polymerization tanks are thin films (including strands) K
By doing so, the ethylene glycol release area per unit polymer volume was increased by 7, and the reaction was greatly accelerated. As a result of greatly increasing the reaction rate using these thin film polymerization tanks, it has become possible to shorten the residence time of the polymer to 1, and in order to commercialize the polymer before it decomposes, it is possible to achieve high polymerization with fewer carboxy terminals. This makes it possible to obtain polymers of excellent quality.

In addition, in order to obtain a high-quality polyester with a carboxyl terminal of 20 q/T or less, the reaction internal temperature (T″C
) and the average residence time (0 minutes) of the thin film polymerization tank must be operated so that the following relationship is satisfied.

0<θ≦480-1.5 T However, 280≦T If the residence time is longer than this range, the effect of thermal decomposition will be large, and the carboxyl end concentration of the product will be reduced by 20 eq/
It becomes difficult to maintain the temperature below T, and the object of the present invention cannot be achieved.

Incidentally, the reaction internal temperature T° C. may be the average temperature of the polymer in the polymerization tank, but specifically it is preferably the temperature of the polymer killed at the lower part (outlet part) of the polymerization tank.

The method of the present invention will be explained in more detail below using an example using polyethylene terephthalate, which is a typical thermoplastic polymer, but the present invention is not limited to this example.

In addition, [η] is a phenol solvent and 35
This is the intrinsic viscosity determined from the viscosity measured at °C.

Example-1 Dimethyk terephthalate (DMT) 390 parts/hr and ethylene glycol (EG) 280 parts/hr were mixed with manganese acetate 0.05 mole%/DMT, zinc acetate O
, o 1 moleqb/DMT of the catalyst were continuously supplied to the continuous transesterification reactor 1 shown in FIG. 1, and the transesterification reaction was carried out by heating from 150° C. to 250° C. while distilling methanol off. The residence time was 6 hours.

Then, 0.0% of sonic acid was added to the resulting transesterification reaction product.
After adding 3 mole% of trioxide as a polymerization catalyst to 1 mole%/DMT%, it was continuously fed to the initial polymerization tank 2 and heated to 50°C mjig, 26
The reaction was carried out at 0°C for 1 hour to obtain a polymer with (w) = 0.15. Add this to 1 in a molten state. The reaction was carried out in medium-term polymerization tank 3 at 5 mHg and 280°C for 2 hours.
=0.5 polymer was obtained. Next, this was continuously trap-feeded in a molten state to the thin film polymerization tank shown in Figure 4 at 1 wx.
M9. React at 300°C for 20 minutes (η) = 1
．． 0, carboxyl end l1ll! Concentration 13 eq/T
of polymer was obtained.

Example-2 Using the same process as Example-1 (Fig. 1), iIL
Only the final polymerization tank was a thin film polymerization tank shown in Figure 3, and the reaction was carried out at 300°C for 25 minutes using 0.5 to 1 g, [η) =
1.0 and a carboxyl terminal concentration of 17 eq/T was obtained.

Comparative Example-1 The same bath (Fig. 1) as in Example-1 was used, but the particles were made into fine particles upon exiting the middle stage 1 mixing tank 3 for use in solid phase polymerization, and (q) = 0.5 got a tip.

Place the chips in a tumbler batchwise at 230°C.
The reaction was carried out under the condition of 1 m29. It took 23 hours to obtain [ri]=1.0, and the obtained terminal carboxyl group concentration was 25 eq/T.

Comparative Example 2 The same Buxes (Fig. 1) as in Example 1 was used, but as the final polymerization tank, a conventional deaf horizontal #1 fusion polymerization tank was used.
5 tm'd9 and reacted in the dark at 300° C. for 1.5 hours. The obtained polymer had [η]=0.8. The carboxyl terminal concentration was 45 eq/T, and the carboxyl terminal increased due to decomposition without increasing [η].

Comparative Example-3 A reaction was carried out in the same manner as in Example-1, but the operating conditions in the final polymerization tank were changed to 3wM9. The reaction was carried out at 300°C for 40 minutes.

A value of 1.0 was obtained, but the carboxyl terminal concentration was 27·q/ because the reaction time was long relative to the temperature.
It was T.

Effects of the Invention According to the present invention, compared to the conventional solid phase polymerization method (based on
The polymerization time can be greatly reduced, and the trouble of forming vertical grains can be omitted, making it possible to significantly reduce costs in terms of energy and labor. The resulting polymer is a high-quality polyester with a low concentration of carboxyl terminals and is useful as a material for fibers, films, and other molded products.

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram for carrying out the present invention, and FIGS. 2 to 5 are schematic illustrations of a thin film polymerization tank used in the present invention. 2... Initial polymerization tank, 3... Mid-term polymerization tank, 4... Thin film polymerization tank

Claims (1)

[Claims] 1. In producing a polyester with a high degree of polymerization by a continuous melt polymerization method, a thin film polymerization tank is used as the final stage reaction tank, and the average residence time (θ) of the thin film polymerization tank is A method for producing a highly polymerized polyester, which is characterized in that the operation is performed so that the internal reaction temperature (T° C.) satisfies the following relational expression. 0<θ≦480-1.5T However, 280≦T 2. The thin film polymerization tank has stirring blades arranged concentrically in the circumferential direction, and the rotation of the stirring blades causes the flow to flow down along the tank wall. A method for producing a highly polymerized polyester according to claim 1, which comprises forming a thin polymer film. 3. The thin film polymerization tank has one or more cylindrical or cylindrical roller-shaped stirring blades, and the stirring blades are caused to move planetarily in the circumferential direction along the tank wall, so that the polymerization tank flows down to the tank wall in the form of a thin film. A method for producing a high degree of polymerization polyester according to claim 1, which comprises forming a polymer layer.