JP2010265352A - Method and apparatus for producing polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology that can produce a polyester of high quality excellent in heat resistance and homogeneity by controlling condensation-polymerization and radical polymerization properly. <P>SOLUTION: The method for producing polyester involves using an aliphatic glycol and an aliphatic dicarboxylic acid as main components, adding thereto at least one of an unsaturated glycol, whose straight chain carbon number is equal to the aliphatic glycol and the total carbon number is ≤1, and an unsaturated dicarboxylic acid, whose straight chain carbon number is equal to the aliphatic glycol and the total carbon number is ≤1, and synthesizing a straight chain polymer having weight average molecular weight of at least 20,000 by condensation polymerization followed by esterification reaction under environment of reduced pressure, and then forming crosslinking between unsaturated carbons in the polymer by performing radical polymerization reaction by addition of a radical polymerization initiator and by mixing using a biaxial stirrer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for producing a polyester polymer such as polybutylene succinate.

  In recent years, biomass-derived polyester has attracted attention from the viewpoint of oil removal. Among them, polyethylene succinate (PES), polytrimethylene terephthalate (PTT), polybutylene succinate (PBS) and the like are synthesized by condensation polymerization of glycol and dicarboxylic acid such as polyethylene terephthalate. These are synthesized using at least one of aliphatic glycols (ethylene glycol, 1,3-propanediol, 1,4-butanediol) or succinic acid which is a dicarboxylic acid. For example, PBS described below is a bioplastic having biodegradability synthesized by a polymerization reaction of 1,4-butanediol (1,4-BDO), which is a bio-derived material, and succinic acid (FIG. 1). . PBS is attracting attention as an alternative material for general-purpose plastics manufactured from petroleum-derived materials such as polypropylene and polyethylene, but compared with these, improvement in heat resistance and impact resistance is a problem. One means for improving these is a method of increasing the degree of crosslinking of the resin. As an example, Patent Document 1 describes a technique for increasing the degree of crosslinking of PBS using a polyvalent isocyanate. In this method, 1,4-butanediol and succinic acid are esterified, then a catalyst is added and a polycondensation reaction is performed under reduced pressure, and then a polyvalent isocyanate is added and mixed to obtain FIG. A heat-resistant property and the like are improved by introducing a cross-linked structure with urethane bonds into the polymer. However, since the polyvalent isocyanate added as a resin modifier has a molecular structure greatly different from that of the PBS skeleton, the homogeneity and crystallinity of the plastic may be lowered.

  Similarly, Patent Document 2 discloses a technique using malic acid as a modifying agent for PBS. The degree of crosslinking is increased by adding malic acid to 1,4-butanediol and succinic acid and conducting an esterification reaction, followed by condensation polymerization under reduced pressure and introducing the crosslinked structure shown in FIG. 3 into the polymer. This method is superior in terms of plastic homogeneity because malic acid having a molecular structure similar to that of succinic acid, which is a raw material for PBS, is used as a modifier. However, since the degree of crosslinking is increased only by condensation polymerization, if the reaction conditions are not precisely controlled, it is difficult to control the growth of side chains, and the increase in molecular weight is hindered by the cyclic polymerization of hydroxy groups in the polymer. There is a case.

  On the other hand, Patent Document 3 and Non-Patent Document 1 report a technique for increasing the degree of crosslinking of PBS using unsaturated dicarboxylic acid. According to this document, 1,4-butanediol, succinic acid, and itaconic acid and fumaric acid, which are unsaturated dicarboxylic acids having the same linear carbon number as succinic acid, are mixed and esterified in a flask. The molecular weight is increased by the condensation polymerization reaction. By adding and mixing a radical polymerization initiator such as benzoyl peroxide to this, the carbon double bond existing in the itaconic acid skeleton part in the polymer is cleaved, and radical polymerization is performed, so that the material shown in FIG. The cross-linked structure shown is introduced. This method is superior in terms of homogeneity because an acid having a carbon number and molecular structure similar to those of succinic acid is used as a modifier. Moreover, since radical polymerization is performed after increasing the molecular weight by condensation polymerization, the problem of gelation which becomes a problem during the condensation polymerization reaction can be avoided. However, it is necessary to mix a radical polymerization initiator with a high-viscosity polymer whose viscosity has been increased by condensation polymerization in the flask, which is problematic in terms of mixing speed and uniformity of both, and the average polymerization degree of radical polymerization. The distribution may not be stable.

Japanese Patent No. 2825969 JP 2008-94888 A Japanese Patent No. 2699802

Naozumi Teramoto et.al., Crosslinking and biodegradation of poly (butylene succinate) prepolymers containing itaconic or maleic acid units in the main chain, J. Appl Polymer Sci, 2005, 95 (6), 1473-1480

  An object of the present invention is to provide a technique capable of producing a high-quality polyester excellent in heat resistance and homogeneity by appropriately controlling condensation polymerization and radical polymerization.

  As a result of investigations to solve the above problems, the inventors of the present invention mixed and esterified aliphatic glycol, aliphatic dicarboxylic acid, and unsaturated glycol and / or unsaturated dicarboxylic acid, and then polymerized the polymer by condensation polymerization. After the molecular weight is sufficiently increased and the viscosity is increased, a radical polymerization initiator is added, and a polymerizer equipped with a biaxial agitator (hereinafter referred to as a biaxial polymerizer) having excellent stirring and mixing performance with respect to a high-viscosity fluid. The above-mentioned problems can be solved by mixing in the above method, and the present invention has been completed.

  That is, the present invention includes the following.

(1) Unsaturated glycols and aliphatic dicarboxylic acids having aliphatic glycols and aliphatic dicarboxylic acids as main raw materials, and having the same number of straight chain carbon atoms as aliphatic glycols and a total carbon number difference of 1 or less. Is added to and mixed with at least one unsaturated dicarboxylic acid having the same number of straight-chain carbon atoms and a total carbon number difference of 1 or less, followed by esterification and subsequent polycondensation reaction under reduced pressure. A linear polymer of 20,000 or more is synthesized, a radical polymerization reaction is performed by adding a radical polymerization initiator and mixing using a biaxial stirrer to form a bridge between unsaturated carbons in the polymer. , Production method of polyester.

(2) Production of polyester according to (1), characterized in that the aliphatic glycol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, and the additive is itaconic acid or fumaric acid. Method.

(3) A raw material adjusting tank for mixing at least one of aliphatic glycol and aliphatic dicarboxylic acid as main raw materials and unsaturated glycol and unsaturated dicarboxylic acid as additives, and oligomer by esterifying the mixture An esterification tank for producing a polyester, a catalyst addition apparatus for adding a catalyst to the oligomer, and a polyester production apparatus having a condensation polymerization tank for condensation-polymerizing the oligomer to produce a polymer, wherein a radical is provided after the condensation polymerization tank. A polyester production apparatus comprising: a polymerization initiator addition apparatus and a biaxial polymerization apparatus, or at least one biaxial polymerization apparatus equipped with a radical polymerization initiator addition apparatus as a condensation polymerization tank.

(4) A twin-screw stirrer provided in the twin-screw polymerization vessel is provided with two stirring shafts having a stirring blade having a surface substantially perpendicular to the flow of the molten polymer. The rotation direction of the agitation shaft is the same, the rotation axis of the agitation does not have an axis, or the agitation blades provided on each of the agitation shafts are in opposite directions with a phase difference of 90 degrees from each other. The polyester production apparatus according to (3), wherein at least one condition for rotation is satisfied.

(5) The polyester production apparatus according to (3), wherein the biaxial agitator provided in the biaxial polymerization apparatus is a biaxial agitator that does not have an actual axis at the rotation center of agitation.

  According to the present invention, a polymer excellent in uniformity, thermal stability, high temperature strength, and low colorability can be obtained. Moreover, since radical polymerization is performed after performing condensation polymerization, inhibition of increase in the molecular weight of the polymer due to side chain cyclic polymerization, which is a problem during the condensation polymerization reaction, can be suppressed.

The molecular structure of PBS is shown. The cross-linked structure introduced into PBS by polyvalent isocyanate is shown. The cross-linked structure introduced into PBS by malic acid is shown. The cross-linked structure introduced into PBS by itaconic acid is shown. An embodiment of the polyester manufacturing apparatus of the present invention is shown. 1 shows an embodiment of an intermediate condensation polymerization tank (wheel blade polymerizer) used in the polyester production apparatus of the present invention. 1 shows an embodiment of a twin-screw stirrer (glasses blade polymerizer) used in the polyester production apparatus of the present invention. 1 shows an embodiment of a twin-screw stirrer (high shear blade polymerizer) used in the polyester production apparatus of the present invention. An embodiment of the polyester manufacturing apparatus of the present invention is shown. An embodiment of the polyester manufacturing apparatus of the present invention is shown. 1 shows an embodiment of a twin-screw stirrer (lattice blade polymerizer) used in the polyester production apparatus of the present invention. An embodiment of the polyester manufacturing apparatus of the present invention is shown. An embodiment of the polyester manufacturing apparatus of the present invention is shown. An embodiment of the polyester manufacturing apparatus of the present invention is shown. An embodiment of the polyester manufacturing apparatus of the present invention is shown. An embodiment of the polyester manufacturing apparatus of the present invention is shown.

  In one embodiment, the present invention relates to an unsaturated glycol having an aliphatic glycol and an aliphatic dicarboxylic acid as a main raw material, and an aliphatic glycol and an aliphatic glycol having the same straight chain carbon number and a total carbon number difference of 1 or less as an additive. And at least one unsaturated dicarboxylic acid having the same straight chain carbon number as that of the aliphatic dicarboxylic acid and a total carbon number difference of 1 or less, and mixing, esterification reaction and subsequent polycondensation under reduced pressure environment A linear polymer having a weight average molecular weight of 20,000 or more is synthesized by a reaction, and a radical polymerization reaction is performed by adding a radical polymerization initiator and mixing using a biaxial stirrer to form a bridge between unsaturated carbons in the polymer. It is related with the manufacturing method of polyester characterized by the above-mentioned.

  In the polyester production method of the present invention, aliphatic glycol, aliphatic dicarboxylic acid, and unsaturated glycol and / or unsaturated glycol are mixed and esterified, and the molecular weight of the polymer is sufficiently increased by condensation polymerization to increase the viscosity. Thereafter, a radical polymerization initiator is added, and mixing is performed in a polymerization apparatus provided with a biaxial stirrer having excellent stirring / mixing performance for a high-viscosity fluid. The polyester production method of the present invention is a method for continuously producing polyester.

  In the polyester production method of the present invention, since the stirring and mixing properties in the radical polymerization step are improved, it is possible to increase the molecular weight of the polymer and the melt viscosity associated therewith in the condensation polymerization step. Further, since the radical polymerization initiator can be uniformly dispersed by mixing using a biaxial stirrer, radical polymerization can be promoted uniformly, and the distribution of the degree of crosslinking of the polymer is also made uniform. With these effects, the uniformity, thermal stability, high temperature strength, and low colorability of the polymer can be improved efficiently. In addition, by improving the mixing property and uniformity, it is possible to avoid an event in which the concentration of the radical polymerization initiator is uneven and the catalyst is locally insufficient, so the amount added must be reduced to the minimum required amount. Can do. At that time, since the steps are divided into condensation polymerization and radical polymerization, inhibition of polymer cyclization and increase in molecular weight due to simultaneous occurrence of linear polymerization and side chain polymerization can be suppressed.

  In the method for producing a polyester of the present invention, first, an aliphatic glycol and an aliphatic dicarboxylic acid and an additive, an unsaturated glycol and / or an unsaturated dicarboxylic acid, are mixed to perform an esterification reaction. The esterification reaction is carried out under a pressure of about atmospheric pressure and a nitrogen atmosphere at a temperature of 185 to 240 ° C. for 1 to 5 hours, preferably at a temperature of 200 to 230 ° C. for 2 to 3 hours.

  Next, a condensation polymerization catalyst is added to the oligomer obtained by the esterification reaction, and the condensation polymerization reaction is carried out under reduced pressure. The addition amount of the condensation polymerization catalyst is usually 100 to 5,000 ppm, preferably 500 to 2,000 ppm based on the aliphatic dicarboxylic acid. A polycondensation reaction proceeds by transesterification at the end of the oligomer to produce a polymer. As the condensation polymerization catalyst, a wide range of catalysts used for transesterification can be used. For example, as the catalyst, a metal compound containing a metal such as Li, Mg, Ca, Ba, La, Ce, Ti, Zr, Hf, V, Mn, Fe, Co, Ir, Ni, Zn, Zr, Ge, and Sn , For example, organic metal compounds such as organic acid salts, metal alkoxides and metal complexes (such as acetylacetonate), inorganic materials such as metal oxides, metal hydroxides, carbonates, phosphates, sulfates, nitrates and chlorides Metal compounds are exemplified. Among these metal compound catalysts, titanium compounds, particularly organic titanium compounds such as titanium alkoxides such as titanium tetraethoxide, titanium tetraisopropoxide, and titanium tetrabutoxide are preferable. A catalyst can be used individually or in combination of 2 or more types.

  A linear polymer having a weight average molecular weight of 20,000 or more, preferably 20,000 to 50,000, more preferably 20,000 to 30,000 is synthesized by a condensation polymerization reaction. A radical polymerization reaction is performed by mixing using a stirrer to form a bridge between unsaturated carbons in the polymer. The radical polymerization reaction is performed at 130 to 240 ° C., preferably 130 to 160 ° C. for 0.5 to 2 hours under a pressure of about atmospheric pressure and a nitrogen atmosphere, and the molecular weight is about 2 to 3 times in terms of weight average. Increase.

  The addition amount of the radical polymerization initiator is usually 1 to 10 wt%, preferably 2 to 5 wt% with respect to the unsaturated dicarboxylic acid. The radical polymerization initiator is not particularly limited, but superoxides such as di-α-cumyl peroxide, cumene hydroperoxide, and t-butyl peroxybenzoate are preferable.

  In the present invention, the biaxial stirrer is not limited as long as it stirs by rotation about two stirring shafts, and includes a case where an actual shaft is not provided at the rotation center. The biaxial stirrer is a biaxial stirrer in which stirring blades having a plane perpendicular to the flow of the molten polymer are provided on two stirring shafts, and the rotation directions of the stirring shafts are the same. Or at least one condition that the stirring blades provided on each of the stirring shafts rotate in the opposite direction with a phase difference of 90 degrees from each other, or have an actual shaft at the rotation center of the stirring It is preferable to use those not present. By using a biaxial polymerization apparatus provided with these biaxial stirrers, the mixing of radical polymerization initiators and radical polymerization can be carried out more uniformly and efficiently. The biaxial polymerization vessel is preferably a horizontal polymerization vessel in which the stirring axis of the stirrer is substantially horizontal.

  Such a biaxial polymerization apparatus includes a high shear blade polymerization apparatus (Japanese Patent Laid-Open No. 8-252822), a lattice blade polymerization apparatus (Japanese Patent No. 1899479), and a spectacle blade polymerization apparatus (Japanese Patent No. 4112908) manufactured by Hitachi Plant Technology. )

  The high shear blade polymerizer is provided with two stirring shafts substantially having a vertical surface with respect to the flow of the molten polymer, and the rotation directions of the stirring shafts are the same. A shaft stirrer is provided. At that time, the gap width between adjacent stirring blades is usually as small as 1 cm or less. As a result, the melt in the gap between the stirring blades that normally rotate at a high speed of 10 rpm or more is stretched in the upside down direction by the blades, thereby obtaining a large shear stress. The stretched melt then reaches the melt liquid level in the polymerization vessel and coalesces. By this stretching and subsequent coalescence, that is, folding, an additive such as a radical polymerization initiator can be mixed in the melt with high viscosity in a very short time. This makes it possible to minimize the residence time of the polymer in the polymerization vessel in the radical polymerization step, and contributes to the reduction of the polymer coloring associated with thermal degradation.

  The twin-screw stirrer provided in the spectacle blade polymerizer is a twin-screw stirrer in which two stirring shafts are provided with stirring blades having a surface substantially perpendicular to the flow of the molten polymer, A stirrer in which eyeglass-like stirring blades provided on each of the stirring shafts rotate in opposite directions with a phase difference of 90 degrees from each other. In other words, the biaxial stirrer provided in the spectacle blade polymerizer is one in which spectacle-shaped stir blades are installed alternately vertically and horizontally with respect to two stirring shafts. The stirring shaft rotates in the direction of meshing with each other (reverse direction). Along with this, the melt is stretched left and right by the adjacent stirring blades, and then reaches the melt liquid level in the polymerization vessel and unites. . This stretching and subsequent coalescence, i.e. folding, makes it possible to mix. Adjacent stirring blades installed on the opposite stirring shaft are 90 degrees out of phase with respect to the installation direction. This makes it possible to scrape off the melt adhering to the opposite stirring shaft with the stirring blade (self-cleaning function). The viscosity of the melt handled by the spectacle blade polymerizer is preferably about 100 to 3,000 Pa · s. Therefore, the spectacle blade polymerizer is advantageously used when the condensation polymerization reaction is not completely completed in the condensation polymerization tank and the condensation polymerization reaction and the radical polymerization reaction proceed simultaneously.

  The biaxial stirrer provided in the lattice blade polymerizer is a stirrer that does not have an axis at the rotation center of stirring although the rotation direction of the stirring shaft is opposite. The lattice blade polymerizer is suitably used for mixing a polymer having a high viscosity, for example, a polymer having a viscosity of 500 to 5000 Pa · s. Since the stirrer of the lattice blade polymerizer does not have a shaft at the center of rotation, a part of the polymer does not adhere to the shaft and cannot be mixed. Similarly to the spectacle blade polymerizer, the melt is stretched left and right by the adjacent stirring blades that rotate in the meshing direction (reverse direction), and then reaches the melt level in the polymerizer. To do. By this stretching and subsequent coalescence, that is, folding, it becomes possible to mix an additive such as a radical polymerization initiator in the high-viscosity melt. Although the mixing effect due to the shear stress is slightly inferior to that of the high shear blade polymerizer, the adhesion of the polymer on the stirring shaft and the accompanying co-rotation phenomenon (the stirring speed is larger) In addition, when the viscosity of the melt rises significantly, the effect of gravity acting on the polymer lifted by the blade is smaller than the viscosity force, so that the melt is not mixed in the circumferential direction of the stirring blade ) And polymer thermal decomposition / coloring suppression performance is further improved.

  In the method of the present invention, since an unsaturated glycol and / or an unsaturated dicarboxylic acid is added to an aliphatic glycol and an aliphatic dicarboxylic acid and then subjected to radical polymerization, radical polymerization is performed. It is possible to suppress polymer gelation and molecular weight increase inhibition due to cyclic polymerization of end groups, which is a problem when increasing the molecular weight only by condensation polymerization of the above polymers, increasing the degree of crosslinking and molecular weight of the polymer, and heat resistance It is possible to improve high temperature strength. Only one or both of unsaturated glycol and unsaturated dicarboxylic acid may be added.

  The addition amount of the unsaturated glycol is usually 1 to 30 mol%, preferably 5 to 10 mol% with respect to the aliphatic glycol, and the addition amount of the unsaturated dicarboxylic acid is usually 1 to 30 mol% with respect to the aliphatic dicarboxylic acid. , Preferably 5 to 10 mol%.

  When an unsaturated glycol is added as an additive, an aliphatic glycol that is a main raw material is equal to a straight chain carbon number and the total carbon number difference is 1 or less. Also, when an unsaturated dicarboxylic acid is added as an additive, an aliphatic dicarboxylic acid that is a main raw material is equal to the straight chain carbon number and the total carbon number difference is 1 or less. Here, the straight carbon number means the number of carbon atoms contained in the shortest chain connecting two hydroxyl groups of aliphatic glycol, and the carbon atom contained in the shortest chain connecting two carboxyl groups of aliphatic dicarboxylic acid. The number of The difference in total carbon number of 1 or less means that the difference between the number of all carbon atoms contained in the aliphatic glycol and the number of all carbon atoms contained in the unsaturated glycol is 1 or 0, and that the aliphatic dicarboxylic acid The difference between the number of all carbon atoms contained in the acid and the number of all carbon atoms contained in the unsaturated dicarboxylic acid is 1 or 0. By adding the unsaturated dicarboxylic acid and / or unsaturated diol as described above as an additive, the degree of crosslinking and molecular weight can be increased by radical polymerization without distorting the polymer skeleton, thereby improving the uniformity of the polymer. it can.

  Examples of the aliphatic glycol include aliphatic glycols having 3 to 6 carbon atoms, preferably 4 to 5 carbon atoms. Specific examples include 1,4-butanediol and 1,5-pentanediol. Examples of the aliphatic dicarboxylic acid include aliphatic glycols having 3 to 6 carbon atoms, preferably 4 to 5 carbon atoms. Specific examples include succinic acid and glutaric acid. Specific examples of combinations of aliphatic glycols and unsaturated glycols, and combinations of aliphatic dicarboxylic acids and unsaturated dicarboxylic acids are listed in the following table.

  When PBS is produced using 1,4-butanediol as an aliphatic diol and succinic acid as an aliphatic dicarboxylic acid as main raw materials, itaconic acid and / or fumaric acid having the same carbon skeleton as succinic acid as an unsaturated dicarboxylic acid Since the crosslinking degree and molecular weight can be increased by radical polymerization without distorting the PBS main body skeleton, the uniformity of the polymer can be improved.

  In the method of the present invention, since the weight average molecular weight of the linear polymer is increased to 20,000 or more in the condensation polymerization stage, the heat resistance and high temperature strength of the polymer can be improved, and radical polymerization is started. Since the addition amount of the agent can be reduced, deterioration and decomposition of the polymer can be suppressed. On the other hand, since the molecular weight is increased at the condensation polymerization stage, the viscosity of the polymer is increased, but the high viscosity polymer and the radical polymerization initiator can be rapidly mixed by mixing using a biaxial stirrer. Can do. As a result, the distribution of the degree of crosslinking in the polymer can be made uniform, so that a technique capable of polymerizing a high-quality polymer excellent in heat resistance and homogeneity can be provided.

  The present invention also relates to a polyester production apparatus for carrying out the above polyester production method. The polyester production apparatus of the present invention comprises at least a raw material adjusting tank for mixing at least one of an aliphatic glycol and an aliphatic dicarboxylic acid as main raw materials, and an unsaturated glycol and an unsaturated dicarboxylic acid as additives, and the mixture described above. Esterification tank for esterifying the oligomer to form an oligomer, a catalyst addition device for adding a catalyst to the oligomer, and a condensation polymerization tank for condensation polymerization of the oligomer to produce a polymer, and radical polymerization at the latter stage of the condensation polymerization tank An initiator addition device and a biaxial polymerization vessel are provided, or at least one biaxial polymerization vessel provided with a radical polymerization initiator addition device as a condensation polymerization tank is provided.

  The aliphatic glycol and aliphatic dicarboxylic acid as the main raw material, the unsaturated glycol and unsaturated dicarboxylic acid as the additive, the biaxial polymerizer, the catalyst and the reaction conditions are as described for the polyester production method. The polyester production apparatus of the present invention is an apparatus for continuously producing polyester.

  In the raw material adjusting tank, aliphatic glycol and aliphatic dicarboxylic acid as raw materials and unsaturated glycol and / or unsaturated dicarboxylic acid as additives are mixed and stirred at a predetermined ratio. The raw material slurry obtained in this way is supplied to an esterification tank, and esterification reaction is performed. The outer periphery of the esterification tank usually has a jacket structure in order to keep the reaction solution at the reaction temperature, and a heat medium can be circulated through the jacket.

  The oligomer obtained by the esterification reaction is sent to a condensation polymerization tank. At this time, the condensation polymerization catalyst is added by the catalyst ignition device. It is preferable to add a condensation polymerization catalyst after the esterification reaction tank. Thereby, deactivation of the catalyst due to moisture generated in the esterification reaction can be suppressed. Further, the residence time can be strictly controlled by line-mixing the condensation polymerization catalyst. In the polycondensation tank, the polycondensation reaction proceeds by a transesterification reaction at the end of the oligomer to produce a polymer.

  It is preferable to provide a plurality of condensation polymerization tanks. For example, it can be provided in three stages of an initial condensation polymerization tank, an intermediate condensation polymerization tank, and a final condensation polymerization tank, or in two stages of an initial polymerization tank and a final polymerization tank. The condensation polymerization tank is not particularly limited, and for example, a lattice blade polymerization device, a high shear force polymerization device, a spectacle blade polymerization device, and a wheel blade polymerization device can be used. The wheel blade polymerizer is equipped with a plurality of wheel-shaped stirrer blades perpendicular to the stirring shaft, and the melt is lifted by a plurality of scraping plates installed perpendicularly to the wheel blades and their circumferences. Then, it is repeatedly dropped by gravity and united with the liquid surface, and stirring is advanced. The scraper plate installed vertically around the wheel blades also has a function of peeling off the melt adhering to the inner wall surface of the polymerization vessel. The melt handled in the wheel-blade polymerizer is usually in a viscosity region of about 1 to 300 Pa · s, which is not so high, and it is desirable to install a multistage weir in the polymerizer from the viewpoint of securing plug flow properties. In the condensation polymerization tank, the condensation polymerization reaction is carried out until a linear polymer having a weight average molecular weight of 20,000 or more is synthesized.

  The polyester production apparatus of the present invention includes a radical polymerization initiator addition apparatus and a biaxial polymerization apparatus in the subsequent stage of the condensation polymerization tank, or a biaxial polymerization apparatus equipped with a radical polymerization initiator addition apparatus as the condensation polymerization tank. At least one is provided.

  When the radical polymerization initiator addition device and the biaxial polymerization vessel are provided in the subsequent stage of the condensation polymerization tank, the reaction solution after the final condensation polymerization is sent to the biaxial polymerization vessel as the radical polymerization vessel. In that case, a radical polymerization initiator is added with the addition apparatus of a radical polymerization initiator. The radical polymerization initiator may be added from a supply line immediately before the radical polymerization tank, or may be added from the upper part of the radical polymerization tank toward the melt surface. Considering that the radical polymerization reaction starts instantaneously immediately after the addition of the radical polymerization initiator, the latter method of starting the reaction and mixing simultaneously is desirable. The biaxial polymerization vessel as the radical polymerization vessel is preferably the above-mentioned lattice blade polymerization device, high shear force polymerization device, or spectacle blade polymerization device.

  In the case where at least one biaxial polymerization reactor equipped with a radical polymerization initiator addition device is provided as a condensation polymerization tank, it is not necessary to provide a radical polymerization tank separately from the condensation polymerization tank. A polymerization reaction and a radical polymerization reaction are carried out. In this embodiment, when there is only one condensation polymerization tank, the condensation polymerization tank becomes a biaxial polymerization reactor equipped with a radical polymerization initiator addition device, and when there are a plurality of condensation polymerization tanks, Preferably, the final stage polycondensation tank is a biaxial polymerization apparatus equipped with a radical polymerization initiator addition device. Adding a radical polymerization initiator from the position where the weight average molecular weight of the polymer reaches 20,000 or more, preferably 20,000 to 50,000, more preferably 20,000 to 30,000 inside the condensation polymerization tank. Thus, the radical polymerization tank can be omitted.

  Hereinafter, 1,4-butanediol as an aliphatic diol and succinic acid as an aliphatic dicarboxylic acid are used as main raw materials, and PBS is produced using itaconic acid having the same carbon skeleton as succinic acid as an unsaturated dicarboxylic acid. A specific example will be described with reference to the drawings. A polymer can be similarly produced when other main raw materials and additives are used.

  FIG. 5 is a block diagram of the PBS manufacturing apparatus of the present invention. (111) is a raw material adjustment tank in which 1,4-butanediol, which is a raw material of PBS, succinic acid, and itaconic acid, which is an additive (modifier), are mixed and stirred at a predetermined ratio. The amount of itaconic acid added is 1 to 30 mol%, preferably 5 to 10 mol%, based on succinic acid. 1,4-butanediol as a liquid is charged into the raw material adjusting tank from the charging port (101), and succinic acid and itaconic acid as powders are charged into the raw material adjusting tank from the charging ports (102) and (103) using a hopper. Since the succinic acid and itaconic acid that have been charged do not dissolve in 1,4-butanediol, they are dispersed while stirring with the stirring blade (112) of the raw material adjusting tank (111). When the particle size of succinic acid and itaconic acid is large and the sedimentation rate is high, the raw material slurry is passed through the circulation line (104) using the raw material slurry circulation pump (121) installed at the lower part of the raw material adjustment tank (111). A method of circulating and preventing sedimentation is effective.

  The raw material slurry adjusted to a predetermined composition is supplied to the esterification tank (211) using the raw material slurry feed pump (131), and at a pressure of about atmospheric pressure and a temperature of 185 to 240 ° C. under a nitrogen atmosphere. The esterification reaction is performed for 1 to 5 hours, preferably at a temperature of 200 to 230 ° C. for 2 to 3 hours. Although not shown, the outer peripheral portion of the esterification tank (211) has a jacket structure in order to keep the reaction liquid at the reaction temperature, and a heat medium can be circulated through the jacket. The water generated by the esterification is in the form of a vapor, which is sent to the overhead system (201) and condensed together with the vaporized 1,4-butanediol and the reaction by-product tetrahydrofuran.

  The prepolymer having undergone the esterification reaction is fed to the initial condensation polymerization tank (311) using a prepolymer feed pump (221). At this time, a polycondensation catalyst is added from a polycondensation catalyst supply line (203) serving as a catalyst addition device, which joins the prepolymer supply line (202) at the latter stage of the esterification tank. There are two reasons why the catalyst is added from the downstream piping of the esterification reaction tank. The first reason is to suppress the deactivation of the catalyst due to moisture generated in the esterification reaction, and the second reason is that the residence time can be strictly controlled by line mixing. The addition amount of the catalyst is 100 to 5,000 ppm, preferably 500 to 2,000 ppm with respect to succinic acid.

  The mixture of the raw material liquid and the polycondensation catalyst is stored in the initial polycondensation tank (311) at a vacuum degree of 650 to 10,000 Pa, 210 to 250 ° C. for 1 to 5 hours, preferably a vacuum degree of 1,000 to 3,000 Pa, 220. The polycondensation reaction is performed at ˜240 ° C. for 2 to 4 hours. The degree of polymerization of the reaction solution is about 20-40. The acceleration of the polymerization reaction is due to the transesterification reaction at the terminal of the oligomer, and it is necessary to devolatilize 1,4-butanediol which is a by-product generated at that time. The produced 1,4-butanediol is volatilized and removed together with the low molecular weight polymer centered on the oligomer and the water produced by the esterification reaction of some terminal groups.

  The prepolymer supplied from the lower part of the initial condensation polymerization tank (311) is also discharged from the outlet at the lower part, but it is necessary to control the residence time in the continuous processing, so the prepolymer is discharged from the supply port. A cylindrical partition plate is provided so as not to perform a shortcut. As a result, the residence time can be controlled, so that a high-quality polyester having a uniform molecular weight distribution can be produced. The initial condensation polymerization tank (311) has a stirring blade shape as shown in FIG. 6 so that the inside and the outside of the cylindrical partition plate can be uniformly mixed with the same stirring blade, and the outer peripheral portion has a jacket structure. The reaction temperature can be optimally controlled by a heating medium. The liquid feed to the initial condensation polymerization tank (311) is controlled by controlling the number of revolutions of the raw material feed pump (221) so that the liquid level of the initial condensation polymerization tank (311) can be maintained at a predetermined height. 1,4-Butanediol generated by the condensation polymerization reaction, tetrahydrofuran as a by-product, volatilized oligomer and low-molecular monomer are evacuated to the overhead system (301). Although not shown, the overhead system is processed by a vacuum system including a catch pot, a condenser, a cold trap, an ejector, or a vacuum pump. When maintaining a vacuum with an ejector, what is driven by 1,4-butanediol as a raw material is desirable. Thereby, what was used with the ejector can be returned to a polymerization raw material, and a raw material yield can be improved.

  The reaction liquid after the completion of the initial condensation polymerization is sent to the intermediate condensation polymerization tank (411) by the liquid feed pump (321). In the intermediate condensation polymerization tank (411), the condensation polymerization reaction is carried out for 1 to 3 hours at a vacuum degree of 300 to 2,000 Pa and 220 to 250 ° C. Thereby, the polymerization degree of the reaction solution is about 60 to 130. FIG. 6 shows an example in which a uniaxial wheel blade polymerization vessel is employed as the intermediate condensation polymerization tank (411). The intermediate condensation polymerization tank (411) has a jacket structure, and the reaction temperature can be optimally controlled by a heating medium. In addition, the liquid feeding amount of the liquid feeding pump (321) is controlled so that the liquid level of the intermediate condensation polymerization tank is constant. Further, 1,4-butanediol generated by the condensation polymerization reaction, tetrahydrofuran as a by-product, oligomers, and low molecular weight monomers are treated in the same manner as the overhead system of the initial condensation polymerization tank, and thus description thereof is omitted.

  The amount of liquid fed to the reaction liquid after the completion of the intermediate polymerization is adjusted by the liquid feed pump (421) so that the liquid level of the final condensation polymerization tank (511) maintains a predetermined value. In the final condensation polymerization tank (511), condensation polymerization is carried out for 1 to 3 hours at a degree of vacuum of 50 to 400 Pa, 220 to 250 ° C. Thereby, the polymerization degree of the reaction solution becomes about 100 to 200. In this embodiment, a biaxial spectacle blade polymerizer (FIG. 7) is used for the final condensation polymerization tank (511). In addition, the volatile component generated in the condensation polymerization reaction is evacuated to the overhead system (501) and treated in the same manner as the overhead system of the intermediate condensation polymerization tank.

  The reaction solution after the final polycondensation is sent to the radical polymerization tank (611) using a feed pump (521). At that time, the radical polymerization initiator is combined with the final polymerization polymer supply line (502) immediately before the radical polymerization tank (611), from the radical polymerization initiator supply line (503) as an addition device for the radical polymerization initiator. Added. Or it adds toward the liquid level of a melt from the upper part of a radical polymerization tank. The addition amount of the radical polymerization initiator is desirably reduced to 1 to 10 wt%, preferably 2 to 5 wt% with respect to succinic acid. This embodiment of FIG. 5 is an example in which a high shear force polymerization apparatus (FIG. 8) is used as the radical polymerization tank (611). In addition, as shown in FIG. 9, it is possible to omit the intermediate condensation polymerization tank by carrying out the condensation polymerization reaction in the intermediate condensation polymerization tank in the initial condensation polymerization tank (311) or the final polymerization tank (511). .

  FIG. 10 shows an example of the polyester production apparatus of the present invention using the lattice blade polymerizer shown in FIG. 11 in the radical polymerization tank. FIG. 12 shows an example of the polyester production apparatus of the present invention in which the intermediate condensation polymerization tank of the polyester production apparatus of FIG. 10 is omitted. FIG. 13 is an example of the polyester production apparatus of the present invention using the spectacle blade polymerizer shown in FIG. 7 in the radical polymerization tank. FIG. 14 shows an example of the polyester production apparatus of the present invention in which the intermediate condensation polymerization tank of the polyester production apparatus of FIG. 13 is omitted. FIG. 15 shows that the radical polymerization tank is omitted by increasing the molecular weight in the final condensation polymerization tank to 20,000 or more, which improves heat resistance and impact resistance, and the molecular weight of the polymer in the final condensation polymerization tank is 20,000 or more. It is an example of the polyester manufacturing apparatus of this invention which adds a radical polymerization initiator from the position which reached | attained. FIG. 16 is an example of the polyester production apparatus of the present invention in which the intermediate condensation polymerization tank of the polyester production apparatus of FIG. 15 is omitted.

  In the radical polymerization reaction, polymerization is performed at a pressure of about atmospheric pressure and a nitrogen atmosphere at 130 to 240 ° C., preferably 130 to 160 ° C. for 0.5 to 2 hours, and the molecular weight is about 2 to 3 times in terms of weight average. Increase to. In this case, in consideration of generation of reaction heat accompanying radical polymerization reaction and avoidance of reaction runaway, polymerization at a temperature not higher than the melting point of PBS is desirable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the scope of the present invention is not limited to this.

(Example)
PBS was manufactured using the apparatus of FIGS. 5, 6, 7, and 8 using succinic acid and 1,4-butanediol as main raw materials and itaconic acid as an additive. Succinic acid and 1,4-butanediol were the same weight, and the amount of itaconic acid added was 10 mol% with respect to succinic acid. These mixtures were esterified at a temperature of 210 ° C. for 5 hours under a 1 atm nitrogen atmosphere. After completion of esterification, 1,000 ppm of titanium tetrabutoxide as an amount with respect to succinic acid was added to the obtained oligomer as a catalyst, and initial polycondensation was performed at a vacuum degree of 2,000 Pa and 230 ° C. for 3 hours. The obtained prepolymer was supplied to a wheel blade polymerizer, and subjected to intermediate condensation polymerization at a vacuum degree of 400 Pa and 240 ° C. for 2 hours. The obtained prepolymer was supplied to a spectacle blade polymerizer, and final condensation polymerization was performed at 100 Pa, 240 ° C. for 2 hours. As a result, a polymer having a weight average molecular weight of 30,000 and a melt viscosity of about 1,000 Pa · s was obtained. While supplying the obtained polymer to a high shear blade polymerizer, at the polymer supply port position of the polymerizer, 10 wt% of benzoyl peroxide was added and mixed as a radical polymerization initiator from above the liquid level and mixed at 1 atm. Under a nitrogen atmosphere, radical polymerization was performed at 140 ° C. for 1 hour. As a result, the molecular weight was doubled by weight average, and PBS excellent in heat resistance and impact resistance could be synthesized.

(Comparative example)
Of the devices used in the examples, the spectacle blade polymerizer, which is the final condensation polymerization tank, is deleted, and a wheel different from that used in intermediate condensation polymerization instead of the high shear blade polymerizer, which is a radical polymerizer, is used. PBS was polymerized under the same polymerization conditions using a blade polymerization apparatus. As a result, a prepolymer having a weight average molecular weight of 5,000 was obtained at the end of the intermediate condensation polymerization, and the molecular weight after radical polymerization was doubled on a weight average basis. The obtained polymer had a smaller molecular weight than the examples, and was inferior in heat resistance and impact resistance.

101… 1,4-butanediol supply line
102… Itaconic acid supply line
103… Succinic acid supply line
104… Raw material slurry circulation line
105… Raw material slurry supply line
111… Raw material adjustment tank
112… stirring blade
121… Raw material slurry circulation pump
131… Raw material slurry supply pump
201… Overhead system of esterification tank
202… Prepolymer supply line
203… Condensation polymerization catalyst supply line
211… Esterification tank
221… Prepolymer pump
301… Initial condensation polymerization tank overhead system
302… Initial polycondensation polymer supply line
311… Initial condensation polymerization tank
321… Liquid pump for initial condensation polymer
401… Intermediate condensation polymerization tank overhead system
402… Supply line for intermediate condensation polymer
411… Intermediate condensation polymerization tank
421… Intermediate condensation polymerization polymer feed pump
501… Overhead system of final condensation polymerization tank
502… Final condensation polymer supply line
503… Radical polymerization initiator supply line
511… Final condensation polymerization tank
521… Final polycondensation polymer feed pump
601… Radical polymerization tank overhead system
602… Radical polymerization polymer discharge line
611… Radical polymerization tank

Claims (5)

  An aliphatic glycol and an aliphatic dicarboxylic acid are used as main raw materials, and as an additive, an aliphatic glycol and an aliphatic glycol and an aliphatic dicarboxylic acid having a total carbon number difference equal to or less than 1 At least one unsaturated dicarboxylic acid having the same carbon number and a total carbon number difference of 1 or less is added and mixed, and an esterification reaction and a subsequent polycondensation reaction in a reduced pressure environment result in a weight average molecular weight of 20,000. The above-mentioned linear polymer is synthesized, a radical polymerization reaction is performed by adding a radical polymerization initiator and mixing using a biaxial stirrer to form a bridge between unsaturated carbons in the polymer. Production method.   The method for producing a polyester according to claim 1, wherein the aliphatic glycol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, and the additive is itaconic acid or fumaric acid.   A raw material adjusting tank for mixing at least one of aliphatic glycol and aliphatic dicarboxylic acid as main raw materials and unsaturated glycol and unsaturated dicarboxylic acid as additives, and esterifying the mixture to produce oligomers An esterification tank, a catalyst addition apparatus for adding a catalyst to the oligomer, and a polyester production apparatus having a condensation polymerization tank for producing a polymer by condensation polymerization of the oligomer, wherein a radical polymerization initiator is provided downstream of the condensation polymerization tank. An apparatus for producing polyester, comprising: an addition device and a biaxial polymerization device, or at least one biaxial polymerization device equipped with a radical polymerization initiator addition device as a condensation polymerization tank.   The biaxial stirrer provided in the biaxial polymerizer is a biaxial stirrer in which stirring blades having a surface perpendicular to the flow of the molten polymer are provided on two stirring shafts. The rotating direction of the stirring shafts is the same, or at least one condition that the stirring blades provided on each of the stirring shafts rotate in the opposite direction with a phase difference of 90 degrees is satisfied. The polyester manufacturing apparatus according to claim 3.   The polyester manufacturing apparatus according to claim 3, wherein the biaxial agitator provided in the biaxial polymerization apparatus is a biaxial agitator having no actual axis at the rotation center of agitation.

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