JPH0364534B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for continuously polymerizing polyester, particularly polyethylene terephthalate, using a thin film polymerization reactor.

Prior art The synthetic polymer of polyester has excellent physical properties.
Due to its chemical properties, it is widely used for various purposes. In particular, polyethylene terephthalate has excellent chemical resistance, heat resistance, insulation resistance, high gas barrier properties, high strength, and high elastic modulus, and is used in large quantities for clothing, industrial fibers, films, containers, general molded products, etc. It is used in Traditionally, a switch from batch polymerization to continuous polymerization has been made in order to take advantage of economies of scale and produce at low cost. It has become necessary to produce a wide variety of polymers in small quantities. In this case, a small-capacity thin film polymerization reactor is used in order to take advantage of the continuous polymerization method and produce polymers for diversified applications. For example, as shown in Japanese Patent Application Laid-Open No. 58-96627, the prepolymer from the polymerization machine in the previous stage of the final stage is fed to at least two final polymerization machines connected in parallel, and general-purpose products have conventionally been used. Alternatively, monomers and/or low polymers can be produced in large quantities using a horizontal reactor, and special brands can be produced in a small thin film polymerization reactor (tank) that can be easily switched. feed in parallel to the line, and each line uses one or several small thin film polymerization devices (tanks) in series.
There are methods such as manufacturing different special brands on each line.

In such a thin film polymerization reaction apparatus, the reaction methods include: a method of providing high-speed stirring using a stirring blade, a method of creating a gravity-flowing film using a wet wall, or a method of creating a large number of thin filaments to evaporate volatile by-products. There are methods to increase the surface area. Among these methods, a high reaction rate is obtained by forcefully stirring the reactants, thereby renewing the surface of the reactants and facilitating removal of volatile by-products, which is the most desirable method. However, in this method, (A) If the shaft has a central shaft and the stirring blades are installed on this shaft, the shaft and the mounting part of the stirring blades will not get wet due to the polymer and will become a so-called dead space, where scattered objects will remain for a long period of time. There was a drawback that gel-like foreign matter formed in the process.

(B) In addition, when installing stirring blades in a cage-shaped cylinder that does not have a central axis, it is true that there is less adhesion of polymer particles to the central axis and the blade attachment part, but since it does not have a central axis, the strength However, it was not possible to increase the rotational speed, and therefore the surface area of the thin film polymer was not sufficiently renewed by shearing, making it difficult to significantly improve the reaction rate.

(C) To further eliminate dead space,
A mechanism with planetary motion as shown in Publication No. 48-13240 has been considered, but in this device (i) high speed rotation is not possible because the wall and blade are in contact, and the reaction speed is low. improvement is not sufficient.

(ii) The directions of revolution and rotation are opposite, and the circumferential speeds cancel each other out, so the reaction speed is not sufficiently improved.

(iii) It has disadvantages such as a large number of driving gears and a complicated mechanism such as a spherical joint for bringing the walls and blades into contact within the reaction tank.

Purpose and Structure of the Invention The present invention has been made against the background of the above circumstances, and its purpose is to obtain a high reaction rate while suppressing decomposition using a thin film polymerization tank, and to remove foreign matter generated from a dead space. The aim is to efficiently and inexpensively produce polyester of good quality by eliminating the need for polyester by melt polymerization.

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

That is, in producing polyester by a continuous melt polymerization method, the present invention employs an agitation method in which a cylinder or a cylindrical body that rotates closely along a substantially cylindrical vertical tank wall is formed with multiple spiral grooves. A thin film polymerization apparatus having one or more rollers is used, and the stirring roller is moved in a planetary motion in the circumferential direction along the tank wall so that the rotation direction and the revolution direction are the same, and the polyester monomers supplied from the upper part of the tank wall are The polymer and/or its low polymer are applied to the stirring roller and the inner wall of the tank.
A method for producing polyester characterized by performing a reaction by renewing the surface and applying a shearing force to form a thin film on the wall of a tank while flowing down, and a method for producing polyester that is performed in close proximity along a substantially cylindrical vertical tank wall. A polyester manufacturing apparatus having a thin film type polymerization tank equipped with one or more stirring rollers each having a rotating cylinder or a cylindrical body with multiple spiral grooves, the tank having a circumferential main gear in order from the top; The upper disk, lower disk, and stirring roller are arranged such that the main gear is fixed in the tank, the upper and lower disks and the stirring roller are not fixed, and the main gear, upper and lower disks are mainly driven by their center. A shaft passes through the main drive shaft, the main drive shaft plays with the main gear, the upper and lower disks are fixed to at least one of them, and the upper and lower disks are rotatably moved between the upper and lower disks by one or more support shafts via bearings. This polyester manufacturing apparatus is characterized in that a planetary gear meshing with the main gear is fixed to the upper end of the support shaft, and a stirring roller is fixed to the lower part of the support shaft.

In the present invention, when polyester monomers and/or their low polymers are introduced into a vertical reactor heated and maintained in a vacuum state to continuously polymerize polyester, a spiral multi-row groove is formed. A thin film is formed on the tank wall and the stirring roller by causing a stirring roller made of a column or cylindrical body formed with a cylindrical shape to move planetarily along the tank wall in the circumferential direction with the rotation direction and the revolution direction in the same direction. The main feature is that the total circumferential speed of the stirring blade relative to the tank wall, including rotation and revolution speed, is 0.3 m/sec or more, and the clearance between the tank wall and the stirring blade is 5 mm or less, preferably 0.5 to 5 mm. By narrowing the width, effective shear is applied to the polymer between the tank wall and the stirring blade at high speed, greatly improving the reaction speed, and the stirring roller is completely wetted, almost completely preventing the occurrence of dead space. making it possible to do so.

Additionally, in this case, it is preferable to provide the stirring blade with a groove structure of a scraping type in order to provide a polymer feeding mechanism, but when reacting monomers or low polymers with extremely low melt viscosity, grooves with a scraping type structure are preferably provided. It can be done.

Here, the polyester referred to in the present invention is polyethylene terephthalate obtained by esterifying or transesterifying and polycondensing terephthalic acid or terephthalic acid dialkyl ester (alkyl group usually has 1 to 4 carbon atoms) and ethylene glycol. The main target is terephthalic acid or a part (usually 20 mol% or less) of terephthalic acid dialkyl ester, for example, aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, and aliphatic acids such as adipic acid and sebacic acid. Alkyl esters such as oxycarboxylic acids such as dicarboxylic acids may be substituted, and part or all of ethylene glycol may be replaced with HO such as propylene glycol and tetramethylene glycol.
You may substitute with the glycol represented by ( _CH2 )n(H (n is 3-10).

In the present invention, manganese compounds, zinc compounds, magnesium compounds, etc. are used as transesterification catalysts, but there is no need to limit them as long as they have transesterification ability, and examples include inorganic compounds such as halides and oxides, and organic acids. Among these salts, particularly preferred are organic acid salts such as acetate, propionate, salicylate, and benzoic acid.

The present invention will be explained below based on the drawings. FIG. 1 is a perspective sectional view of a specific example of the polymerization apparatus according to the present invention, and FIG. 2 is an enlarged perspective view of the drive mechanism section of FIG. 1. In the figure, reference numeral 11 denotes a cylindrical tank body, which is provided with a shaft sealing chamber 14 in the upper part and a take-out chamber 36 in the lower part.
2 is surrounded and a heating jacket chamber 13 is formed between the tank body 11 and the tank body 11. A drive shaft 15 passing through the center of the shaft sealing chamber 14 is rotatably supported via a bearing 16, and the upper end of the drive shaft 15 is directly connected to a drive body via a pulley (not shown) or the like. A shaft sealing means 17 such as a mechanical seal is provided at the lower end of the shaft sealing chamber 14 to seal the tank body 11 so as to withstand high vacuum.

Bolts 19 are attached to the partition plate 18 at the top of the tank body 11.
A stationary main gear 20, which is fixed to the main gear 20 through disk 2
1, 22 have through holes 23, 24, 25 in the center.
The drive shaft 15 passes through the through holes 23 to 25 and reaches the lower disk 22 (it may also pass through the lower disk 22). The drive shaft 15 passes through the main gear 20 in an idle state without contacting it,
The upper and lower disks 21 and 22 are fixed and integrated with a key or the like (not shown). This fixation is preferably performed by the upper and lower disks 21 and 22, but the upper and lower disks 21 and 22
It is also possible to use only one of these.

A plurality of through holes 26 and 27 are provided in the upper and lower disks 21 and 22 in correspondence with each other (six holes are equally spaced in FIG. 1). The support shaft 30 is rotatably held via the provided bearings 28 and 29, and both are connected and fixed. A planetary gear 31 that meshes with the main gear 20 is fixed to the upper end of the support shaft 30, and a cylindrical stirring roller 32 is connected to the lower part extending from the lower disk 22 so as to be close to the inner wall of the tank. Two or more stirring rollers 32 (support shafts 30) are usually mounted at equal intervals for balance, but it is also possible to use only one stirring roller 32 (support shaft 30).

A large number of diagonal grooves 33 are carved in an uneven shape on the outer periphery of the side surface of the lower disk 22, and a reaction liquid supply nozzle 34 is provided on the opposing inner wall of the tank, and the reaction liquid fed from the supply nozzle 34 is fed to the lower disk 2.
The reaction liquid is dispersed by hitting the uneven portions of the lower disk 22, and the lower disk 22 has a function as a polymer dispersion.

The diagonal grooves (irregularities) 33 for dispersing the polymer are carved in a direction in which force is applied to the reaction solution downward in response to rotation, and the angle α thereof is preferably about 10 to 30 degrees.

The stirring roller 32 normally has a spiral groove 35 formed around the entire circumference to provide a downward feeding action, but when the reaction liquid has a low viscosity, a spiral groove 35 is formed in the opposite direction to provide a stirring action. A shaped groove may be formed. The stirring roller 32 is arranged so as to rotate close to the inner wall of the tank, but the distance between the two, that is, the clearance between the outer diameter of the stirring roller 32 (the convex surface when it has grooves 35) and the inner wall of the tank is 5 mm or less, preferably 0.5 to 5 mm. It is preferable to set the thickness to 5 mm, especially 0.5 to 3 mm. If this clearance exceeds 5 mm, shot passes will increase, the reaction speed will not increase, and dead spaces will likely occur. Moreover, if it is less than 0.5 mm or if it is in constant contact with the inner wall of the tank, the stirring resistance becomes large and it may become difficult to provide an appropriate circumferential speed to impart effective shear to the reaction liquid. In this case, in order to apply particularly effective shear to the reaction liquid, promote mixing, and accelerate the reaction speed, the stirring roller is moved in a planetary motion so that its rotation direction and revolution direction are the same, and its circumferential speed and rotation speed are It is preferable that the total speed of the rotation speed and the revolution speed is 0.3 m/sec, particularly preferably 0.5 m/sec or more. Even if the above-mentioned planetary motion is performed at a speed of 0.3 m/sec or less, the reaction may not proceed sufficiently and it may not be possible to stably obtain a product of excellent quality.

Reaction liquid extraction chamber 3 located at the bottom of the tank body 11
6 is provided with a nozzle 37 for taking out the reaction liquid at the lower end, and a nozzle 38 for vacuum suction is attached to the side part.

In such an apparatus, when the drive shaft 15 is rotated by a drive means (not shown), the upper and lower disks 21, 22 are rotated in the direction of the arrow as shown in FIG. Due to this rotation, the planetary gear 31 meshes with the main gear 20 and rotates around it, and at the same time rotates itself in the same direction. Therefore, the stirring roller 32 approaches the inner wall of the tank and rotates along the inner wall of the tank in the direction of rotation. Planetary motion is performed so that the direction of revolution is in the same direction.

In the jacket 13, the tank body 11 and the extraction chamber 36 are heated to a predetermined temperature by a heating means such as a heating medium, and at the same time, the tank body 11 and the like are maintained in a high vacuum by a nozzle 38 communicating with the vacuum generating means. The raw material liquid (monomer or prepolymer, hereinafter referred to as polymer) supplied from the nozzle 34 at the top of the tank main body is dispersed almost uniformly in the circumferential direction by the rotating lower disk 22 and applied to the inner wall of the tank.

The polymer flows downward while being sheared by the stirring roller 32 that rotates in the same direction as the revolution direction. In this way, the polymer is coated on the stirring roller 32 and the inner wall of the tank, and moves downward while being subjected to effective shearing due to the clearance with the wall surface while undergoing surface renewal. quickly forms a thin film-like reaction surface, and the reaction takes place very quickly.

As is well known, the rate of polycondensation reactions in polymers is determined by the diffusion of diol (for example, ethylene glycol in polyester), which is a reaction product in the polymer, but by adopting the mechanism described above, the reaction rate can be greatly increased. can be obtained.

Another advantage is that the wings are completely wet,
So-called dead space does not occur. For example, as shown in FIG.
In the case of reactor 3 with It has the disadvantage of becoming a gel-like foreign substance.

In addition, in order to change the reaction capacity, etc. (intrinsic viscosity difference between polymer inlet and outlet, production amount, etc.), there are a plurality of, preferably 3 or more, 4 to 6 transparent membranes in the upper and lower disks 21 and 22. It is preferable to provide the holes 26 and 27 so that the stirring blades 32 can be replaced or increased or decreased as necessary.By doing this, the flexibility of the conventional reaction tank can be improved with the same main body size. It becomes possible to change the reaction ability beyond Tei.

EXAMPLES The method of the present invention will be explained in more detail in the following examples using polyethylene terephthalate, which is a typical thermoplastic polymer, but the present invention is not limited to these examples.

Note that [η] is the intrinsic viscosity determined from the viscosity measured at 35° C. using orthochlorophenol as a solvent.

Example 1 Dimethyl terephthalate (DMT) 390 parts/hr and ethylene glycol (EG) 280 parts/hr manganese acetate 0.05 mole%/DMT, zinc acetate 0.01 mole
%/DMT to the continuous transesterification reactor 5 shown in FIG. 3, and heated from 150° C. to 250° C. while distilling methanol off to carry out the transesterification reaction. The residence time was 6 hours.

Next, 0.1 mol% of phosphoric acid/DMT and 0.03 mol% of antimony trioxide/DMT as a polymerization catalyst were added to the obtained transesterification product, and the mixture was continuously fed to the initial polymerization tank 6 at 50 mmHg and 260°C.
The mixture was reacted for 1 hour to obtain a polymer with [η]=0.15.
Further, this is heated to 5mm in the medium-term polymerization tank 7 while still in a molten state.
The reaction was carried out at 280° C. for 2 hours to obtain a polymer with [η]=0.5. Next, this was continuously fed in a molten state to the thin film polymerization tank (device) 10 shown in Fig. 1, and reacted for 20 minutes at 1 mmHg and 300°C [η]=
1.0, a polymer with a carboxyl terminal concentration of 13 eq/T was obtained.

Here, two stirring rollers with spiral grooves 2 mm deep for stirring down the polymer are installed throughout the thin film polymerization tank shown in Figure 1, and the directions of rotation and revolution are the same, and the total speed of these rollers is The circumferential speed is 0.5 m/sec, and the clearance between the stirring roller and the tank wall is 2.
I drove it as mm. When I disassembled and inspected the aircraft after driving it for a month, I found that there was no dead space in the wings.

Comparative Example 1 The same process as in Example 1 (Fig. 3) was used, but the stirring blade drive mechanism of the polymerization tank was
Almost the same conditions as Example 1 for the internal gear type planetary mechanism shown in the publication (reaction conditions, stirring blade rotation speed, etc.)
I drove it with the directions of revolution and rotation reversed. The total circumferential speed of the stirring blades is faster when rotating, 0.05 m/sec.
However, effective stirring could not be obtained and the resulting polymer could only reach [η]=0.60, meaning that a sufficient reaction rate could not be obtained. The rotation speed was further increased to reach the capacity limit, but the total circumferential speed of the stirring blades was
It should not be more than 0.15m/sec, and the [η] of the polymer
However, no value exceeding 0.64 was obtained.

Comparative Example 2 The same process as in Example 1 (Fig. 3) was used, but the reaction tank was one in which a stirring blade was installed on the central axis as shown in Fig. 4. The circumferential speed of the wing is 0.5
m/sec was set to be the same as in Example-1.

The reaction surface area in this case was less than half that of Example-1, and the resulting polymer increased only up to [η]=0.65, making it impossible to obtain a sufficient reaction rate.

In addition, after continuous operation for one month using this method,
Contamination of gel-like foreign matter into the polymer was observed. Upon disassembly and inspection, it was confirmed that gel-like foreign matter had adhered to the center shaft and the root of the wing, creating a dead space.

Effects of the Invention According to the present invention, the reaction rate is faster than that using a conventional thin film polymerization tank, and foreign matter, especially gel-like foreign matter generated from dead spaces, can be prevented, and polymers of good quality can be stably obtained. becomes possible. Moreover, since the reaction rate is very fast, the resulting polymer can be a high-quality polyester with a low concentration of carboxyl terminals and a high degree of polymerization, making it extremely useful as a material for fibers, films, and other molded products.

[Brief explanation of drawings]

Fig. 1 is a perspective sectional view of a polymerization apparatus showing a specific example of the present invention, Fig. 2 is an enlarged perspective view showing the drive section of Fig. 1, and Fig. 3 is a process diagram for explaining an embodiment of the present invention. , FIG. 4 is an explanatory diagram of a conventional device. 11... Tank body, 14... Shaft sealing chamber, 15... Drive shaft,
20... Main gear, 21... Upper disk, 22... Lower disk, 30... Support shaft, 31... Planetary gear, 32...
Stirring roller, 33...diagonal groove, 35...groove, 36...take-out chamber.

Claims (1)

[Scope of Claims] 1. In producing polyester by continuous melt polymerization, multiple spiral grooves are formed in a cylinder or cylinder that rotates closely along a substantially cylindrical vertical tank wall. Polyester is supplied from the upper part of the tank wall by using a thin film polymerization apparatus having one or more stirring rollers, and moving the stirring roller in a planetary motion in the circumferential direction along the tank wall so that the rotation direction and the revolution direction are the same. The monomer and/or its low polymer is applied to the stirring roller and the inner wall of the tank, and the reaction is carried out by applying surface renewal and shearing force to form a thin film on the tank wall while flowing down. Method of manufacturing polyester. 2. The method for producing polyester according to claim 1, wherein the peripheral speed of the stirring roller relative to the wall surface is 0.3 m/sec or more. 3. A polyester production apparatus having a thin-film polymerization tank equipped with one or more stirring rollers having multiple spiral grooves formed on a cylinder or cylindrical body that rotates closely along a substantially cylindrical vertical tank wall. In the tank, from top to bottom, there are a circumscribed main gear, an upper disk,
The lower disk and stirring roller are arranged such that the main gear is fixed in the tank, and the upper and lower disks and stirring roller are not fixed, and the main drive shaft passes through the center of the main gear and the upper and lower disks. The main drive shaft plays with the main gear, the upper and lower disks are fixed to at least one of them, and the upper and lower disks are rotatably connected and supported by one or more support shafts via bearings. A polyester manufacturing apparatus characterized in that a planetary gear meshing with a main gear is fixed to the upper end of the support shaft, and a stirring roller is fixed to the lower part.