JPS6264822A - Process and apparatus for producing polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester of excellent quality inexpensively in good efficiency, by forming a thin film of a polyester-forming monomer fed from the upper wall of the tank on the wall by effecting a planetary motion of an impeller in a specified direction and at the same time allowing the thin film to flow down along the wall. CONSTITUTION:When a drive shaft 15 is rotated, upper and lower discs 21 and 22 are rotated, a planetary gear 31 coming into mesh with a main gear 20 goes around it and at the same time it is rotated in the same direction. Therefore, a columnar or cylindrical roller impeller 32 kept in the vicinity of the inside wall of the tank performs a planetary motion in which the direction of rotation and that of revolution coincide with each other along the inside wall. A feed solution comprising a polyester-forming monomer and/or its oligomer is sparged in the peripheral direction by means of the lower disc 22 which is rotating and is spread on the inside wall of the tank. During its revolution, the feed solution is sheared by the impeller 32 to refresh its surface and it is allowed to flow down along the inside wall. Therefore, the reaction can be performed very quickly.

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.

Conventional technology Polyester synthetic polymers have 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, high elastic modulus, etc., and is used for clothing, industrial mN, films, containers, etc.
It is used in large quantities as general molded products. 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.However, in order to respond to the diversification of applications in recent years, It has become necessary to produce a wide variety of polymers with different properties for each receiving part. In this case, in order to take advantage of the continuous polymerization method and create polymers for diversified uses,
A small capacity thin film polymerization reactor is used. 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. It is possible to produce large quantities using a horizontal reactor and produce special brands using a small thin film polymerization reactor (tank) that is easy to switch, or to produce large quantities of 7-mer and/or low polymers using tj and polymerize them. In the process, there is a method in which several types of lines are fed in parallel, each line is used with one or several small thin film polymerization devices (tanks) in series, and each line produces different special brands.

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; There are methods to increase the evaporation surface area of living organisms. Among these methods, method (1) is the most desirable because it forcibly stirs the reactants, thereby renewing the surface of the reactants and facilitating the removal of volatile by-products, resulting in a high reaction rate. However, in this method, (A) has a central shaft, and when the stirring blades are installed on this shaft, the parts where the shaft and stirring blades are attached do not get wet due to the polymer, creating a so-called dead space, which prevents debris from adhering to the shaft. There was a drawback that gel-like foreign matter formed over a long period of time.

(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, but since it does not have a central axis, the strength is However, it was not possible to adjust 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. 13240 has been considered, but in this device (1) high speed rotation is not possible because the wall and blade are in contact, and it is difficult to improve the reaction speed. is not enough.

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

(To) It had drawbacks such as a large number of drive gears and a complicated mechanism such as a spherical joint for bringing the walls and blades into contact within the reaction tank.

OBJECT AND CONSTRUCTION OF THE INVENTION The present invention was made against the background of the following circumstances, and its purpose is to obtain a high reaction rate while suppressing decomposition using a thin film polymerization tank, and to reduce the dead space. The aim is to eliminate generated foreign substances and produce 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 polyester by a polyester melt polymerization method that has a high polymerization rate.

That is, the present invention provides a thin film polymerization apparatus for producing polyester by a continuous melt polymerization method, which has one or more cylindrical or cylindrical roller-like stirring blades that rotate closely along a substantially cylindrical vertical tank wall. The polyester monomer and/or its monomer, which is supplied from the section to the tank wall, is stirred by moving the stirring blades in a planetary motion in the circumferential direction along the tank wall so that the rotation direction and the revolution direction are the same. A polyester manufacturing method characterized by forming a polymer in a thin film form on a tank wall surface and flowing it down, and a cylindrical or cylindrical roller-shaped stirring blade that rotates closely along a substantially cylindrical vertical tank wall. This is a polyester manufacturing equipment having a thin film type polymerization tank having one or more of A main drive shaft passes through the section, the main drive shaft plays with the main gear, and is fixed to at least one of the upper and lower disks, and one or more spindles rotate on the upper and lower disks. This polyester manufacturing apparatus is freely installed vertically, has a planetary gear attached to its upper end that meshes with the main gear, and is provided with the stirring blades at its lower part.

In the present invention, when polyester 11-mer and/or its low polymer is introduced into a vertical reactor heated and maintained in a vacuum state to continuously polymerize polyester, a cylindrical or cylindrical roller is used. The main feature is that a thin film is formed on the tank wall and the stirring blade by causing the shaped stirring blade to move planetarily along the tank wall in the circumferential direction with the rotation direction and the revolution direction in the same direction. The total circumferential speed of rotation and revolution speed with respect to the tank wall is 0.3 m/
applying effective shear to the polymer between the tank wall and the stirring blade at high speed by narrowing the clearance between the tank wall and the stirring blade to 5 mm or less, preferably 0.5 to 5 mm; The reaction rate is greatly increased, and the stirring blades wet the entire surface, making it possible to almost completely prevent the generation of dead spaces.

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. Although the main target is
A portion (usually 20 mol % or less) of terephthalic acid or dialkyl terephthalate is added to an oxycarboxylic acid such as an aromatic dicarboxylic acid such as isophthalic acid, phthalic acid, or naphthalene dicarboxylic acid, or an aliphatic dicarboxylic acid such as adipic acid or sepatic acid. An alkyl ester such as an acid may be substituted, and a part or all of ethylene glycol may be replaced with, for example, propylene glycol. HO (CI-12)n (H (n is 3 to 10) such as tetramethylene glycol
) may be substituted with a glycol represented by

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. Salts, etc., and particularly preferred are organic acid salts such as salt-resistant salts, propionates, salicylates, and benzoic acids.

The present invention will be explained below based on the drawings. FIG. 1 is a perspective sectional view of a specific example of a polymerization apparatus according to the present invention.

2 is an enlarged perspective view of the drive mechanism section of FIG. 1. FIG.

In the figure, 11 is a cylindrical tank body with a shaft sealing chamber 14 at the top.
A take-out chamber 36 is provided in the lower part, and an outer cylinder 12 is surrounded over almost the entire outer circumference of the tank body 11, and heating jackets 1 to 13 are formed between the tank body 11 and the outer cylinder 12.

A drive shaft 15 passing through the center of the shaft sealing chamber 14 has a bearing 16.
The upper end of the drive shaft 15 is directly connected to the drive body via a boob (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.

At the top of the tank body 11, a stationary main gear 20 is fixed to the partition plate 18 via bolts 19 and the like. An upper disk 21 and a lower disk 22 of a size close to the inner wall of the tank are arranged at a predetermined interval from above to below, and these main gears 20
, the upper and lower disks 21 and 22 have a through hole 23 in their center.
, 24, 25 are bored, and the through holes 23 to 25 are connected to the drive shaft 1.
5 passes through and reaches the lower disk 22 (it may also pass through the lower disk 22). The drive shaft 15 is the main gear 20
The upper and lower disks 21 and 22 are fixed and integrated with the upper and lower disks 21 and 22 by a key or the like (not shown). Preferably, this fixation is carried out with the upper and lower discs 21.22, but it is also possible to carry out with only one of the upper and lower discs 21.22.

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). A support shaft 30 is rotatably held via provided bearings 28 and 29. 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 roller-shaped stirring blade 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 blades 32 (support shafts 30) are usually installed at equal intervals for balance, but they can also be installed as one.

A large number of diagonal grooves 3 are formed on the outer periphery of the side surface of the lower disk 22 in an uneven manner.
3 is engraved, and a reaction liquid supply nozzle 4J is provided on the inner wall of the opposing tank so that the reaction liquid fed from the supply nozzle 34 hits the uneven portion of the lower disk 22 and is dispersed. The lower disk 22 is adapted to function as a polymer dispersion.

The diagonal grooves (uneven portions) 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 blade 32 normally has a spiral groove 35 formed all around the circumference in order 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 groove may also be formed. Further, the stirring blade 32 is arranged so as to rotate close to the inner wall of the tank, but the distance between them, that is, the outer diameter of the stirring blade 32 (when it has a groove 35, it is a convex surface)
The adhesive clearance between the inner wall of the tank and the inner wall of the tank is preferably 5 mm or less, preferably 0.5 to 5 mm, particularly 0.5 to 3 mm.

If this clearance exceeds 5 mm, short passes will increase, the reaction speed will not increase, and dead spaces will likely occur. Further, if the diameter 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 rate, the stirring blades are moved in a planetary motion so that the direction of rotation and the direction of revolution are the same, and the circumferential speed and rotation speed of the stirring blades are The total speed of orbital speed is 0.3
711/sec, particularly preferably 0.5 rrt/sec or more. Even if the above-mentioned planetary motion is performed at a speed of 0.3 m/sec or more, the two reactions may not proceed sufficiently and it may not be possible to stably obtain a product of excellent quality.

A reaction liquid extraction chamber 36 located at the lower part of the tank body 11 is provided with a nozzle 37 for taking out the reaction liquid at the lower end and a nozzle 38 for vacuum suction at the side part.

In such a device, when the drive shaft 15 is rotated by a drive means (not shown), the upper and lower disks 21, 22 rotate in the direction of the arrow. By this rotation, M
The star gear 31 meshes with the main gear 20 and rotates around it, and at the same time rotates itself in the same direction, so that the stirring blade 32
moves close to the inner wall of the tank and makes a planetary motion along the inner wall of the tank so that the direction of rotation and the direction of revolution are in the same direction.

The tank body 11 is heated to the jacket 13 by heating means such as a heating medium.
．． At the same time as the extraction chamber 36 is heated to a predetermined temperature, the tank body 11 and the like are maintained in a high vacuum by the 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 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 blades 32 that rotate in the same direction as the revolution direction.

In this way, the polymer is coated on the stirring blades 32 and the inner wall of the tank, and moves downward while being subjected to effective shearing due to the clearance between the wall surfaces, while undergoing surface renewal without being resistant. The reaction surface quickly becomes a thin film, 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 (e.g., ethylene glycol in polyester), which is a reaction product in the polymer. You can get speed.

Another advantage is that the buying position is completely wetted, so there is no so-called dead space. For example, as shown in Fig. 4, in the case of a reactor 3 having a central shaft 1 and equipped with stirring blades 2, a thin film-like polymer is produced, but the attachment points for the shaft 1 and stirring blades 2 have roots. There is a disadvantage that the polymer does not get wet, resulting in a so-called dead space, and the adhered particles become gel-like foreign substances over a long period of time.

In addition, in order to be able to change the reaction capacity, etc. (polymer population, intrinsic viscosity difference at the exit, production amount, etc.), there are a plurality of discs, preferably 3 or more, especially 4 to 6, on the upper and lower disks 21 and 22.
It is preferable to provide through holes 26 and 27 so that the stirring blades 32 can be replaced or increased or decreased as needed. It becomes possible to change reaction ability beyond flexibility.

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.

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

Example-1 Dimethyl terephthalate (DMT') 390 parts/hr and ethylene glycol (EG) 280 parts/hr
part/hr to manganese acetate 0.0511101e%/DM
T and zinc acetate 0.01 mole%/DMT catalyst are continuously supplied to the continuous transesterification reactor 5 shown in Fig. 3, and the mixture is heated from 150°C to 250°C while methanol is distilled off to carry out the transesterification reaction. Ta. The residence time was 6 hours.

Then, 0.0% phosphoric acid was added to the resulting transesterification product.
After adding 1 mole%/DM1 and further antimony trioxide (0.03 mole%/r)MT as a polymerization catalyst.

Continuously feed the initial polymerization tank 6 at 50sH (1°26
The reaction was carried out at 0°C for 1 hour to obtain a polymer with [η] = 0.15. Further, this was reacted in a molten state in a medium-term polymerization tank 7 for 5 hours (at 1,280°C for 2 hours), and [η]-〇, 5
of polymer was obtained. Next, this is continuously fed in a molten state to the thin film polymerization tank (device) 10 shown in Fig. 1.
mH(], reacted at 300°C for 20 minutes [η]-
1.0. A polymer with a carboxyl terminal concentration of 13 eq/T was obtained.

Here, two stirring blades with spiral grooves 2 m deep for stirring down the polymer were installed throughout the thin film polymerization tank shown in Figure 1, and the directions of rotation and revolution were in the circumferential direction, and the total speed of these blades was The operation was carried out at a circumferential speed of 0.5 TrL/SeC and a clearance between the stirring blade and the side wall of 2#. 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 replaced with the internal gear type planetary mechanism shown in Japanese Patent Publication No. 13240/1983. It was operated under almost the same conditions (reaction conditions, stirring blade rotation speed, etc.) with the directions of revolution and rotation reversed. The total circumferential speed of the stirrer was 0.05 m/sec, which was faster due to autorotation, but effective stirring was not obtained, and the resulting polymer was [η] = (1,60 m/sec).
However, the reaction speed was not sufficiently high. The rotation speed was further increased to reach the capacity limit, but the total circumferential speed of the stirring blades was 0.15 m/sec or more. I couldn't get anything to surpass it.

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 blade was 0.5 m/88 (i), which was the same as in Example-1.

In this case, the reaction surface area was less than half that of Example-1, and the obtained polymer increased only to [η] -0.65, so that a sufficient reaction rate could not be obtained.

In addition, when this method was continuously operated for one month, gel-like foreign matter was found to be mixed into the polymer. Upon disassembly and inspection, it was discovered 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 in conventional thin film polymerization tanks, and foreign matter, especially gel-like foreign matter generated from dead spaces, can be prevented, and polymers of good quality can be stably produced. It becomes possible to obtain. In addition, since the reaction rate is extremely fast, the resulting polymer can be a high quality polyester with a low concentration of carboxyl terminals and a high polymerization resistance, making it extremely useful as a material for textiles, 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, FIG. 3 is a T-section diagram for explaining the present invention in detail, and FIG. 4 is an explanatory diagram of a conventional device. 11... Tank body, 14... Shaft sealing chamber, 15... Drive shaft. 20...Main gear, 21...''Two-part disc. 22... Lower disk, 30... Support shaft, 31...
planetary gear. 32... Stirring blade, 33... Diagonal groove, 35... Groove. 36... Engraving of the extraction room drawing (Contents - 2 unchanged) Figure 2 F3 Figure 10 + Drawing procedure amendment (released) December 10, 1985

Claims (1)

[Claims] 1. A thin film having one or more cylindrical or cylindrical roller-shaped stirring blades that rotate closely along a substantially cylindrical vertical tank wall when producing polyester by a continuous melt polymerization method. Polyester monomers and/or polyester monomers are supplied from the upper part of the tank wall using a type polymerization apparatus, and the stirring blades are moved in a planetary manner in the circumferential direction along the tank wall so that the rotation direction and the revolution direction are the same. A method for producing polyester, which comprises forming a low polymer in the form of a thin film on the wall of a tank and allowing it to flow down. 2. The method for producing polyester according to claim 1, wherein the peripheral speed of the stirring blade relative to the wall surface is 0.3 m/sec or more. 3. A polyester manufacturing apparatus having a thin film type polymerization tank having one or more cylindrical or cylindrical roller-like stirring blades that rotate closely along a substantially cylindrical vertical tank wall, the upper part of the tank being Circumscribed main gear fixed from top to bottom,
An upper disk and a lower disk are arranged, a main drive shaft passes through the center of these main gears, etc., the main drive shaft plays with the main gear, and the upper and lower disks are fixed to at least one of them. One or more spindles are vertically rotatably installed on the upper and lower disks, a planetary gear that meshes with the main gear is attached to the upper end of the spindle, and the stirring blade is provided at the bottom of the spindle. polyester manufacturing equipment. 4. The polyester manufacturing apparatus according to claim 3, wherein the clearance between the tank wall and the stirring blade is 5 mm or less. 5. The polyester manufacturing apparatus according to claim 3 or 4, wherein the stirring blade has a spiral groove for scraping down or scraping up.