JP2002105184A - Method for continuously producing high-molecular weight polybutylene succinate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a high-molecular weight polybutylene succinate from 1,4-butanediol and succinic acid or its derivative. SOLUTION: A prepolymer formed by a prepolymerization process is further subjected to polycondensation by using a horizontal polymerizer which has a horizontally arranged cylindrical reactor, two rotary trunnions installed side by side at both ends of the reactor in the longer direction and lattice type mixing blades connected to plural rodlike rectangular frames each laid between the rotary trunnions at both ends of the reactor. The horizontal polymerizer is equipped with a rotation mechanism for holding and rotating the two rotary trunnions in such a way that the tip of the rodlike rectangular frame of one mixing blade is passed in close vicinity to the center of the rotation of the other mixing blade.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing polybutylene succinate having a high molecular weight by polycondensing 1,4-butanediol with succinic acid or a derivative thereof. This high molecular weight polybutylene succinate is useful as a material for films, sheets, fibers and other molded articles.

[0002]

2. Description of the Related Art Conventionally, high molecular weight polyesters used for films, sheets, fibers, and other molded products include:
Most aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate were used.

In recent years, from the viewpoint of environmental protection and the like, aliphatic polyesters generally considered to have biodegradability have attracted attention. As a method for producing this aliphatic polyester, an aliphatic dicarboxylic acid and an aliphatic diol are directly esterified, or an alkyl ester of an aliphatic dicarboxylic acid or its anhydride is transesterified with an aliphatic diol to prepare a glycol. Obtaining an ester or a low polymer thereof,
Then, a method is known in which this is heated and stirred under high vacuum to perform polycondensation.

[0004] In such a polycondensation reaction, the molecular weight is increased by removing the eliminated component out of the system. As a method for this, it is common to set the system at high temperature and high vacuum and distill off the desorbed components. For example, JP-A-5-31
No. 0898 discloses that a glycol component is esterified with an aliphatic dicarboxylic acid, and the produced polyester diol is subjected to a temperature of 180 to 230 ° C.
A method for producing a high-molecular-weight aliphatic polyester by performing a glycol removal reaction under a high vacuum of 005 to 0.1 mmHg is disclosed. However, it is not enough to bring the system to high vacuum conditions, and the surface area of the polycondensation reactant is sufficiently increased,
And the surface needs to be updated effectively. This is because the components eliminated in the surface layer of the reactant are more easily distilled off. Particularly in the second half of the polycondensation reaction, the viscosity of the reactant increases, and it becomes difficult to diffuse the desorbed components in the reactant. Therefore, the surface area of the reactant is increased by mechanical stirring to effectively renew the surface. It is necessary. When a polymerization apparatus equipped with a conventional stirring blade is used, such a surface area is not secured and effective surface renewal is not performed, so that the reaction does not proceed sufficiently and a high-molecular-weight aliphatic polyester is obtained. The problem that it cannot be performed arises. With low molecular weight polybutylene succinate, film or sheet molding is difficult.

When polybutylene succinate is obtained by polycondensation of 1,4-butanediol and succinic acid, the polybutylene succinate is subjected to high temperature and high vacuum as disclosed in JP-A-5-310898. In the case of polycondensation, a problem arises in that the once formed polyester is decomposed to generate a large amount of by-products such as tetrahydrofuran. It is very difficult for an actual manufacturing facility to maintain a high vacuum state in a state in which a large amount of volatile components are generated, and even if it can be realized, troubles frequently occur in the vacuum line. It will be inevitable. If efficient stirring can secure the surface area of the reactants and effectively renew the surface,
Even under a low vacuum of 0 mmHg (133 Pa) or more, the desorbed components are easily removed, and high-molecular-weight polybutylene succinate can be efficiently produced.

Furthermore, Japanese Patent Application Laid-Open No. Hei 5-310898 exemplifies the use of a batch polymerization process to increase the molecular weight. However, in order to increase the molecular weight to a level that can be endured as a product, a high-temperature and long-time reaction is required. The product is susceptible to history, and the appearance and thermal stability of the product deteriorate. In order to improve this, a manufacturing method requiring a short residence time at a high temperature is required.

[0007] With the recent increase in demand for biodegradable plastics, it is urgently necessary to secure a supply amount. Batch polymerization processes are inefficient in terms of equipment costs, utility costs, and operability, and there is an urgent need to establish a continuous process capable of mass production.

[0008]

Accordingly, an object of the present invention is to provide a method for efficiently and industrially producing a high molecular weight polybutylene succinate from 1,4-butanediol and succinic acid or a derivative thereof. To provide.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have esterified 1,4-butanediol with succinic acid or a derivative thereof and polycondensed to a predetermined molecular weight. The obtained prepolymer is continuously supplied to a horizontal polymerization apparatus having a specific structure of stirring blades to promote polycondensation, the molecular weight is extremely large, the desorbed components are sufficiently distilled off, and the moldability is excellent. The present inventors have found that polybutylene succinate can be efficiently produced, and have completed the present invention.

That is, the present invention relates to a method for producing polybutylene succinate having a high molecular weight by polycondensing 1,4-butanediol with succinic acid or a derivative thereof. A pre-polymerization step of polycondensing a diol with succinic acid or a derivative thereof to produce a polymer having a polystyrene-equivalent weight average molecular weight of 100,000 or more; (2) a horizontally disposed cylindrical container; It has two rotary ear shafts juxtaposed at both ends in the longitudinal direction, and a grid-type stirring blade connecting a plurality of rod-shaped rectangular frames attached between the rotary ear shafts at both ends of the container. Using a horizontal polymerization apparatus having a rotation mechanism for rotating the two rotating ear shafts while holding them so that the tip of the rod-shaped rectangular frame of one stirring blade passes close to the rotation center of the other stirring blade. Before And a main polymerization step of further polycondensing the polymer produced in the prepolymerization step to produce a high-molecular-weight polybutylene succinate having a weight average molecular weight of 200,000 or more in terms of polystyrene, a method for producing a high-molecular weight polybutylene succinate. To provide.

The prepolymerization step (1) comprises a first prepolymerization step (1a) in which 1,4-butanediol and succinic acid or a derivative thereof are esterified to form a prepolymer having a hydroxyl group at a terminal. A second prepolymerization step (1b) of polycondensing the prepolymer generated in the first prepolymerization step to generate a polymer having a weight average molecular weight of 100,000 or more in terms of polystyrene can be included. The main polymerization step can be performed, for example, at a temperature of 200 to 250 ° C. and a pressure of normal pressure to 0.2 mmHg (26.6 Pa). In addition, succinic acid, dimethyl succinate, or succinic anhydride can be used as succinic acid or a derivative thereof.

[0012]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, 1,4-butanediol is polycondensed with succinic acid or a derivative thereof to produce a high-molecular-weight polybutylene succinate having a polystyrene equivalent weight average molecular weight of 200,000 or more. Examples of succinic acid or a derivative thereof include succinic acid; succinic esters such as dimethyl succinate and diethyl succinate; and succinic anhydride. Among these, succinic acid, dimethyl succinate and succinic anhydride are preferred. Succinic acid or a derivative thereof can be used alone or in combination of two or more.

In the production method of the present invention, a small amount of a glycol component other than 1,4-butanediol may be used, and a small amount of a dicarboxylic acid component other than succinic acid or a derivative thereof may be used.

Examples of the glycol component other than 1,4-butanediol include ethylene glycol,
2-propanediol, 1,3-propanediol,
1,2-butanediol, 1,3-butanediol,
2,3-butanediol, 1,5-pentanediol,
1,2-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, neopentyl glycol, 2,2-diethyl-
Aliphatic glycols having a linear or branched alkylene group such as 1,3-propanediol; epoxides corresponding to 1,2-glycol; trihydric or higher alcohols such as trimethylolpropane; diepoxides And the like. Among these, trimethylolpropane and the like are preferable.

The amount of the glycol component other than 1,4-butanediol used is about 0 to 20 mol% (for example, 0.1 to 20 mol%), preferably 0 to 5 mol% (for example, of the total glycol component). , 0.2 to 5 mol%).

The dicarboxylic acid component other than the succinic acid or a derivative thereof includes a linear or branched dicarboxylic acid such as adipic acid, suberic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, and dimer acid. Dicarboxylic acids having a chain alkylene group; esters of the above dicarboxylic acids such as dimethyl adipate and dimethyl malonate; acid anhydrides such as maleic anhydride, itaconic anhydride and adipic anhydride; malic acid, tartaric acid, citric acid and the like And the like. Among these, an adipic acid derivative such as adipic acid or dimethyl adipate is preferred.

The amount of the dicarboxylic acid component other than succinic acid, dimethyl succinate and succinic anhydride used is about 0 to 35 mol% (for example, 0.5 to 35 mol%), preferably 0 to 35 mol% of the whole dicarboxylic acid component. ~ 25 mol% (for example,
25 mol%).

The amount of the glycol component used in the polymerization varies depending on the desired physical properties of the polyester, but is generally from 1.02 to 1: 1 based on 1 mol of the dicarboxylic acid component.
It is about 5 mol, preferably about 1.03 to 1.2 mol.

The polymerization is usually carried out in the presence of a catalyst.
The catalysts can be used alone or in combination of two or more. As the catalyst, a wide range of catalysts used for transesterification can be used. For example, as the catalyst, a protic acid such as sulfuric acid, p-toluenesulfonic acid, phosphoric acid or a derivative thereof, or Li, Mg, Ca, Ba, La, Ce,
Ti, Zr, Hf, V, Mn, Fe, Co, Ir, N
a metal compound containing a metal such as i, Zn, Ge, or Sn, for example, an organic metal compound such as an organic acid salt, a metal alkoxide, or a metal complex (such as acetylacetonate); a metal oxide, a metal hydroxide, or a carbonate; Examples thereof include inorganic metal compounds such as phosphates, sulfates, nitrates, and chlorides. Among these metal compound catalysts, titanium compounds, particularly titanium tetraethoxide, titanium tetraisopropoxide,
Organic titanium compounds such as titanium alkoxides such as titanium tetrabutoxide are preferred. The use amount of these metal compound catalysts is about 0.005 to 1 mol, preferably 0.01 to 1 mol, per 100 mol of succinic acid or a derivative thereof.
It is about 0.3 mol.

In the method of the present invention, the above-mentioned metal compound catalyst (for example, an organic titanium compound) is used as a catalyst.
An organic or inorganic phosphorus compound may be used in combination.
When the above metal compound and an organic or inorganic phosphorus compound are used in combination, a high molecular weight polymer can be obtained in a short polymerization time.

Examples of the organic or inorganic phosphorus compounds include the following. (A) Phosphoric acid and its organic esters Commercially available products include phosphoric acid; alkyl or aryl acid phosphates (where the alkyl or aryl group has a methyl, isopropyl, butyl, octyl, phenyl, naphthyl group, etc.) and the like. is there.

(B) Phosphonic acid and its organic esters Commercially available products include methylphosphonic acid, ethylphosphonic acid, arylphosphonic acids such as phenylphosphonic acid and naphthylphosphonic acid, and dibutylbutylphosphonate. Examples of the aromatic ring of the arylphosphonic acid include an alkyl group (eg, a C _1-4 alkyl group such as a methyl group), a halogen atom (eg, a fluorine atom and a chlorine atom), and an alkoxy group (eg, a C _1-4 alkoxy group such as a methoxy group). And a substituent such as a nitro group.

(C) Phosphorous acid and organic esters thereof Examples thereof include dibutyl hydrogen phosphite, triphenyl phosphite, diphenyl isodecyl phosphite, and tris isodecyl phosphite.

When a metal compound catalyst and an organic or inorganic phosphorus compound are used in combination as a catalyst, the amount of the organic or inorganic phosphorus compound to be used is 1 to 100 moles relative to the metal compound catalyst (for example, an organic titanium compound). %, Preferably about 5 to 33 mol%.

In the method of the present invention, a high molecular weight polybutylene succinate is produced through a prepolymerization step (1) and a main polymerization step (2). FIG. 1 is a flow sheet showing an example of a production flow in the method of the present invention.

In the pre-polymerization step (1), in the first pre-polymerization step (1a), succinic acid is supplied from the weighing hopper 1;
1,4-butanediol is supplied from the 1,4-butanediol storage tank (1,4-BG storage tank) 2 and the catalyst is supplied from the catalyst mixing tank 3 to the first prepolymerization tank 4 at predetermined temperature and pressure. An esterification reaction is performed to produce a prepolymer having a terminal hydroxyl group. Water and volatile components by-produced in the first pre-polymerization step (1a) are condensed by a condenser and stored in the condensed liquid receiving tank 16.

In the second prepolymerization step (1b), the prepolymer obtained in the first prepolymerization step (1a) is supplied to the second prepolymerization tank 5, where it is further polycondensed at a predetermined temperature and pressure. In this step, the molecular weight is increased mainly by a transesterification reaction (deglycol reaction) between the prepolymers, and an aliphatic polyester having a polystyrene equivalent weight average molecular weight of 100,000 or more is generated. The produced prepolymer is discharged from the second prepolymerization tank 5, cooled in a water tank 6, cut into a desired shape (for example, pellets) by a cutter 7, transferred to a silo 8, and sent to a main polymerization step (2). Can be 1,4-Butanediol and other volatile components by-produced in the second prepolymerization step (1b) are condensed by the condenser and stored in the condensate receiving tank 16.

The water stored in the condensate receiving tank 16, 1,4-
By-products such as butanediol and tetrahydrofuran can be separated and recovered by supplying them to distillation columns 17 and 18 as necessary. The catalyst may be used from the stage of the first prepolymerization step (1a) as in this example, but may be added at the stage of the second prepolymerization step (1b). The polymerization is usually a bulk polymerization in both the first prepolymerization step (1a) and the second prepolymerization step (1b).

As the first pre-polymerization tank 4, a polymerization apparatus usually used when producing polyester by esterification can be used. As such a polymerization apparatus, for example, a vertical stirring tank provided with a stirring blade having a vertical rotation axis (for example, a paddle blade, a helical ribbon blade, or the like) can be used.

The polymerization temperature in the first prepolymerization step (1a) is 140 to 250 ° C., preferably about 145 to 245 ° C. If the temperature is lower than 140 ° C., the reaction rate is low and the practicability is poor. If the temperature exceeds 250 ° C., the produced polymer may be thermally decomposed. The pressure is usually
At normal pressure, the pressure in the system is reduced in the latter half of the reaction, for example, 5 mmHg to 100 mmHg (6
(65 Pa to 13300 Pa).

In the first prepolymerization step (1a), for example, the weight average molecular weight in terms of polystyrene is from 1,000 to 1,
About 0.000 prepolymer is obtained.

As the second pre-polymerization tank 5, a polymerization apparatus usually used for producing polyester or a high-viscosity polymerization apparatus can be used. As such a polymerization apparatus, for example, a vertical stirring tank provided with a stirring blade having a vertical rotation axis (for example, a double helical ribbon blade, a twisted lattice blade, or the like) is exemplified.

The polymerization temperature in the second prepolymerization step (1b) is from 200 to 250 ° C., preferably from about 210 to 240 ° C. If the polymerization temperature is too low, the reaction time will be prolonged, and the production efficiency tends to decrease. On the other hand, if the polymerization temperature is too high, the polymer may be colored or a decomposition product may be easily generated. The reaction time is about 5 to 10 hours.

In the second prepolymerization step (1b), for example, a prepolymer having a weight average molecular weight of 100,000 or more in terms of polystyrene is obtained. If the weight average molecular weight in terms of polystyrene in the second prepolymerization step (1b) is less than 100,000, pelletization is difficult.

In the main polymerization step (2), the prepolymer pelletized in the pre-polymerization step (1) is sent from a silo 8 to an extruder 10 by a quantitative feeder 9 and melt-extruded. Is continuously charged.

One of the main features of the present invention is that, in the main polymerization step (2), a cylindrical container placed horizontally and two rotating ears juxtaposed at both longitudinal ends in the container. Axis and
A grid-type stirring blade connected to a plurality of rod-shaped rectangular frames attached between rotating ear shafts at both ends of the container, and the two rotating ear shafts are rod-shaped rectangular frames of one stirring blade. Is to use a horizontal polymerization apparatus 11 provided with a rotation mechanism for rotating the tip while keeping it so as to pass close to the rotation center of the other stirring blade.

FIG. 2 is a partially sectional plan view showing an example of the horizontal polymerization apparatus 11. FIG. 3 is a sectional view taken along the line III-III of FIG. 2, and FIG. 4 is a perspective view showing a stirring blade of the horizontal polymerization apparatus 11 of FIG.

The polymerization apparatus 11 is installed substantially horizontally, and is provided with a cylindrical container 31 provided with a heating device (such as a heating medium jacket) (not shown), and both ends in the longitudinal direction of the container 31. Two rotating ear shafts 32a and 32b
Between the left and right rotating ear shafts 32a, 32a, and 32
b, 32b, and lattice-type stirring blades 34a and 34b. The rotating ear shafts 32a and 32b are supported by bearings 35 fixed to the side surface of the container 31, and one of the left and right rotating ear shafts is a driving device (not shown).
It is connected to. The lattice type stirring blades 34a and 34b are
Each is formed by connecting a plurality of rod-shaped rectangular frames 33a and 33b with a phase angle of 90 degrees. Further, the stirring blades 34a and 34b are provided with rotating ear shafts 32a and 32b.
When viewed from the direction, the rod-shaped rectangular frames 33a and 33b have a phase angle of 45 degrees with each other, and the tip of one of the rod-shaped rectangular frames 33a and 33b has the other rod-shaped rectangular frames 33b and 33b.
a so as to pass as close as possible to the center of rotation of the container 3a.
1. Rotate at the same speed in opposite directions to each other so as to lift the reaction solution from the bottom to the top inside the container 31 near the inner wall surface. The container 31 has an inlet nozzle 36 and an exhaust nozzle 3
7, and an outlet nozzle (not shown) provided on the opposite side of the exhaust nozzle 37. It is desirable to provide a preheater (not shown) in front of the inlet nozzle 36. The exhaust nozzle 37 is connected to a vent conduit leading to a pressure reducing means (not shown), and the inside of the container 31 is kept at a reduced pressure.

The ratio of the vertical and horizontal lengths of the bar-shaped rectangular frames 33a and 33b is, for example, about 1/3 to 3/1. Rod-shaped rectangular frame 3
The connection number of 3a and 33b is, for example, about 4 to 12. The phase angle between adjacent rod-shaped rectangular frames is not limited to 90 degrees,
For example, an appropriate angle such as 30 degrees, 45 degrees, or 60 degrees can be adopted. Further, the rod-shaped rectangular frame is formed at an appropriate angle in two or more directions when viewed from the direction of the rotating ear axis (for example, 1).
A stirrer may be formed by connecting adjacent rod-shaped rectangular frames with an appropriate (for example, 60 °) phase angle (formed at three angles at an angle of 20 degrees).

In this polymerization apparatus, the stirring blades 34a, 34b
Of the rod-shaped rectangular frames 33a, 33b pass close to the center of rotation of the opposing rod-shaped rectangular frames 33b, 33a, and the stirring action is performed by the rod-shaped structure. Adhesion and scaling of the polymer), and the dead space can be extremely reduced.
Further, the flow of the entire reaction solution in the container 31 can be maintained in a state close to the piston flow, and a good surface renewal effect can be obtained, so that polybutylene succinate having excellent quality can be efficiently obtained. .

The prepolymer produced in the second prepolymerization step (1b) is supplied to the inlet nozzle 3 of the horizontal polymerization apparatus 11
6 and supplied into the container 31 and heated by a heating device (not shown). The supplied polybutylene succinate moves toward the outlet nozzle while being stirred and mixed by the stirring blades 34a and 34b, and is taken out of the pipe using the pump 12 from the outlet nozzle. During this time, the polycondensation reaction further proceeds, and a high-molecular-weight polybutylene succinate having a polystyrene equivalent weight average molecular weight of 200,000 or more is obtained. The produced prepolymer is discharged from the main polymerization apparatus 11, cooled in a water tank 13, and
In 4, the product is cut into a desired shape (for example, a pellet shape), transferred to the silo 15, and packed in a bag to produce a product.
The molecular weight of polybutylene succinate can be adjusted by the reaction temperature, liquid residence time, and the like. 1,4- by-product of the reaction
Volatile substances such as butanediol are discharged from the exhaust nozzle 37 and can be purified and recovered by using a distillation column similar to the above, if necessary.

The number of the horizontal polymerization apparatus 11 may be one.
More than two groups (for example, about two or three groups) may be provided in series.

The polymerization temperature in the main polymerization step (2) is, for example, about 200 to 260 ° C., preferably about 210 to 240 ° C. If the polymerization temperature is too low, the residence time becomes long because the molecular weight is increased, and the production efficiency tends to be reduced. On the other hand, if the polymerization temperature is too high, the polymer is likely to be colored and decomposition products are likely to be generated. The reaction pressure is, for example, normal pressure to 0.2 mm.
Hg (26.6 Pa), preferably 10 to 0.2 mmH
g (133 to 26.6 Pa).

In the main polymerization step (2), the weight average molecular weight in terms of polystyrene is, for example, 200,000 or more, preferably 2,000,000.
10,000 or more, more preferably 220,000 or more (for example, about 220,000 to 250,000) of polybutylene succinate can be obtained.

Incidentally, after an appropriate stage of the above process or after the main polymerization process (2), if necessary, a crystal nucleating agent, a pigment, a dye, a heat stabilizer, an antioxidant, a weathering agent, a lubricant, an antistatic agent , Fillers, reinforcing agents, flame retardants, plasticizers, other polymers and the like may be added.

The high molecular weight polybutylene succinate obtained by the production method of the present invention can be formed into films, sheets, fibers, foams, and other molded products by conventional molding methods such as injection molding, hollow molding, and extrusion molding. can do.
Further, since the high molecular weight polybutylene succinate obtained by the production method of the present invention has biodegradability, trash bags, agricultural films, containers for cosmetics and detergents, fishing lines,
It is suitable for applications such as fishing nets, ropes, surgical threads, food packaging materials, medical containers and the like.

[0047]

According to the method of the present invention, a high molecular weight polybutylene succinate having a weight average molecular weight of 200,000 or more in terms of polystyrene is efficiently produced from 1,4-butanediol and succinic acid or a derivative thereof. it can.

[0048]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The weight average molecular weight in terms of polystyrene was determined by gel permeation chromatography (GPC).

Example 1 An aliphatic polyester was produced according to the production flow shown in FIG. (Preliminary polymerization step) In a nitrogen atmosphere, 1,4-4-staged stirred tank equipped with paddle blades (first preliminary polymerization tank) was placed.
36.25 kg of butanediol, 43.18 k of succinic acid
g, 72.7 g of titanium tetraisopropoxide and 5.1 g of phenylphosphonic acid were collectively charged. Under normal pressure, 14
The mixture was stirred at a temperature of 5 to 225 ° C. to perform an esterification reaction. When the amount of the distillate exceeded 13.0 kg, the first prepolymerization step was completed, and the reaction solution was transferred to a jacketed vertical stirring tank equipped with double helical blades (second prepolymerization tank). The reaction solution in the second prepolymerization tank was stirred at a temperature of 225 to 240 ° C., and finally the pressure was reduced to 1.4 mmHg (186 Pa), and the mixture was stirred for 6 hours to perform a deglycolization reaction (ester exchange reaction). . The reaction product was discharged from the second prepolymerization tank, cooled in a water tank, and cut with a cutter to obtain a pellet-shaped polyester (yield: 55.0 kg). The weight average molecular weight in terms of polystyrene of the prepolymer produced in this prepolymerization step was 1370,000. (Main Polymerization Step) The prepolymer pellets obtained in the pre-polymerization step are fed to a predetermined amount extruder by a quantitative feeder and melted. 11: Hitachi, Ltd. “Hitachi lattice wing polymerization machine” (trade name), material stainless steel]
Were continuously fed. The reaction liquid in the main polymerization tank is 225 to 2
The mixture was stirred at a temperature of 35 ° C. under a reduced pressure of 0.5 mmHg (66.5 Pa), and the glycol removal reaction (ester exchange reaction) was continuously performed with an average residence time of 1 hour. The reaction product was continuously discharged from the main polymerization tank, and cooled in a water tank and cut by a cutter to obtain a pellet-like polyester.
The weight average molecular weight of this polyester in terms of polystyrene was 210,000.

Comparative Example 1 In Example 1, the first prepolymerization step was similarly terminated.
In the second prepolymerization step, a deglycol-reaction was carried out for 8 hours at a temperature of 225 to 240 ° C. and a final pressure reduction of 0.5 mmHg (66.5 Pa) in a polymerization apparatus equipped with a double helical stirring blade. . The reaction product was discharged from the polymerization tank, cooled in a water tank, and cut with a cutter to obtain pelleted polyester (yield: 55.0 kg). The weight average molecular weight in terms of polystyrene of the polyester obtained at this time was 90,000, and although the degree of pressure reduction in the vertical polymerization tank was increased and the reaction time was prolonged as compared with Example 1, a predetermined molecular weight was obtained. Did not reach.

Example 2 A prepolymer obtained by performing prepolymerization in the same manner as in Example 1 was used to prepare a horizontal polymerization apparatus [polymerization apparatus 11: manufactured by Hitachi, Ltd .; Hitachi Lattice Blade Polymerizer "(trade name), stainless steel], and continuously supply the reaction solution at a temperature of 230 to 240 ° C and a pressure of 1.0 m.
The mixture was stirred under a reduced pressure of mHg (133 Pa), and a deglycolization reaction (ester exchange reaction) was continuously performed with an average residence time of 1 hour. The reaction product was continuously discharged from the main polymerization tank, and cooled in a water tank and cut by a cutter to obtain a polyester in the form of pellets. The weight average molecular weight in terms of polystyrene of this polyester was 2190,000.

Example 3 A prepolymer obtained by performing prepolymerization in the same manner as in Example 1 was used to prepare a horizontal polymerization apparatus [polymerization apparatus 11: manufactured by Hitachi, Ltd .; Hitachi Lattice Blade Polymerizer "(trade name), material stainless steel], and continuously supply the reaction solution at a temperature of 225 to 235 ° C. and a pressure of 1.5 m.
The mixture was stirred under a reduced pressure of mHg (200 Pa), and a deglycolization reaction (ester exchange reaction) was continuously performed with an average residence time of 1.8 hours. The reaction product was continuously discharged from the main polymerization tank, and cooled in a water tank and cut by a cutter to obtain a polyester in the form of pellets. The weight average molecular weight in terms of polystyrene of this polyester was 224,000.

Example 4 A prepolymer obtained by performing prepolymerization in the same manner as in Example 1 was used to prepare a horizontal polymerization apparatus [polymerization apparatus 11: manufactured by Hitachi, Ltd .; Hitachi Lattice Blade Polymerizer ”(trade name), material stainless steel], and supply the reaction solution at a temperature of 230 to 240 ° C and a pressure of 1.5 m.
The mixture was stirred under a reduced pressure of mHg (200 Pa), and a deglycolization reaction (ester exchange reaction) was continuously performed with an average residence time of 1.8 hours. The reaction product was continuously discharged from the main polymerization tank, and cooled in a water tank and cut by a cutter to obtain a polyester in the form of pellets. The polystyrene equivalent weight average molecular weight of this polyester was 262,000.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an example of a production flow in the method of the present invention.

FIG. 2 is a partially sectional plan view showing an example of a horizontal polymerization apparatus used in the main polymerization step of the present invention.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a perspective view showing a stirring blade of the horizontal polymerization apparatus of FIG.

[Explanation of symbols]

 4 First pre-polymerization tank 5 Second pre-polymerization tank 11 Main polymerization tank 32a, 32b Rotating ear axis 33a, 33b Rectangular rectangular frame 34a, 34b Grid-type stirring blade 36 Inlet nozzle 37 Exhaust nozzle

Continued on the front page (72) Inventor Kazuo Nakayama 2-74-42, Kariya-cho, Ushiku City, Ibaraki Prefecture (72) Inventor Shigeyuki Yoshida 500-418, Kamiyobe, Yobe-ku, Himeji-shi, Hyogo 161-21-2105 Shimonoda, Shima-ku, Himeji-shi F-term (reference) 4J029 AA03 AB04 AC01 AD01 AE02 AE03 BA05 CA04 HA01 HB01 HB03A KB02 KB16 KC01 KE05 KE12 LA10

Claims (4)

[Claims] 1. A method for producing polybutylene succinate having a high molecular weight by polycondensing 1,4-butanediol with succinic acid or a derivative thereof, comprising:
A prepolymerization step of polycondensing butanediol with succinic acid or a derivative thereof to produce a polymer having a polystyrene-equivalent weight-average molecular weight of 100,000 or more; (2) a horizontally disposed cylindrical container; Has two rotating ear shafts arranged in parallel at both ends in the longitudinal direction, and a grid-type stirring blade connected to a plurality of rod-shaped rectangular frames attached between the rotating ear shafts at both ends of the container. A horizontal polymerization apparatus having a rotation mechanism for rotating the two rotary ear shafts while holding the two rotating ear shafts such that the tip of the rod-shaped rectangular frame of one stirring blade passes close to the rotation center of the other stirring blade. Using, the polymer produced in the pre-polymerization step is further polycondensed,
A main polymerization step of producing a high-molecular-weight polybutylene succinate having a polystyrene-equivalent weight-average molecular weight of 200,000 or more. 2. The pre-polymerization step (1) comprises the step (1a)
A first prepolymerization step in which 1,4-butanediol and succinic acid or a derivative thereof are esterified to form a prepolymer having a hydroxyl group at a terminal; and (1b) a prepolymer formed in the first prepolymerization step. 2. A method for producing high-molecular-weight polybutylene succinate according to claim 1, further comprising a second prepolymerization step of performing polycondensation to produce a polymer having a weight-average molecular weight in terms of polystyrene of 100,000 or more. 3. The method for producing a high molecular weight polybutylene succinate according to claim 1, wherein the main polymerization step is performed at a temperature of 200 to 250 ° C. and a pressure of normal pressure to 0.2 mmHg (26.6 Pa). 4. The method for producing high molecular weight polybutylene succinate according to claim 1, wherein the succinic acid or a derivative thereof is succinic acid, dimethyl succinate or succinic anhydride.