JP2007112995A - Apparatus for heat treatment of polyester particle and method for multistage solid-phase polycondensation of polyester particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for heat treatment of polyester particles suitable for practicing crystallization and solid-phase polycondensation by stepwise raising temperature, particularly an apparatus for heat treatment of polyester particles suitable for obtaining a high-molecular weight polyester by carrying out heat treatment of low-molecular weight polyester prepolymer. <P>SOLUTION: The apparatus for the heat treatment of polyester particles is characterized by comprising (1) a first fluidized bed, (2) a first moving bed, (3) a second fluidized bed, and (4) a second moving bed which are disposed in this order along the flow of the particles, the second moving bed having a capacity at least two times the capacity of the first moving bed. The present invention enables relative simplification of melt polycondensation process and leads to reduction of cost of whole polyester production apparatus. The resultant high-molecular weight polyester is applicable to wide fields such as fibers, clothes, molding resins and bottles for beverages. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat treatment apparatus for polyester particles. Specifically, the present invention relates to a heat treatment apparatus suitable for solid-phase polycondensation of particles made of polyester resin through a multi-stage heat treatment process.

  Polyethylene terephthalate (hereinafter abbreviated as PET) is widely used in many materials and products such as fibers, fabrics, molding resins and beverage bottles.

  In order to extract the moldability and mechanical properties necessary for the above applications, it is necessary to increase the molecular weight (intrinsic viscosity) to a predetermined level. Widely used in Solid phase polycondensation is usually carried out by heat-treating the polyester prepolymer obtained by melt polycondensation under an inert gas atmosphere or under reduced pressure. However, since it takes a relatively long time, the production method is more productive. Is desired. As such a method, a method has been proposed in which a polyester prepolymer having a relatively low degree of polymerization is obtained by melt polycondensation, and this prepolymer is subjected to solid phase polycondensation at a high temperature.

  For example, Patent Document 1 discloses that a polyester prepolymer having an average degree of polymerization of about 5 to about 35 (inherent viscosity of about 0.10 to 0.36 dL / g) obtained by melt polycondensation has an apparent crystallite size of 9 nm or more. However, according to our study, the degree of polymerization at the start of solid phase polycondensation is too low, or the crystal grows to form molecules. A satisfactory solid phase polycondensation reaction rate is not always obtained for the purpose of suppressing the movement of the polymer.

  Patent Document 2 describes solid-phase polycondensation of polyester prepolymer particles having an intrinsic viscosity of 0.08 to 0.5 dL / g at a temperature higher than 140 ° C. from the glass transition temperature. In the temperature range where the particle diameter is about 1 mm or more and the particles are not fused together, a sufficient solid phase polycondensation reaction rate cannot always be obtained.

  Further, Patent Document 3 discloses a solid-phase polycondensation method in which the progress of polymerization takes precedence over the progress of crystallization, that is, a temperature in the range of about 205 to 240 ° C. when low molecular weight polyester prepolymer particles are brought into contact with a heat transfer medium. A method of solid-phase polycondensation in an inert gas stream after raising the temperature to less than 10 minutes is disclosed. In the disclosed method, a thermal shock is applied and the temperature is raised in a very short time to a temperature in the range of about 205 to 240 ° C., so that the particles are easily fused together. It is not always a satisfactory method, for example, it is necessary to devise equipment so as not to bring them into contact with each other, and the effect of shortening the solid phase polycondensation time cannot be obtained by this method.

  On the other hand, Patent Document 4 discloses that two or more moving beds are used in the solid-phase polycondensation step. However, the disclosed technique has a medium molecular weight (in terms of intrinsic viscosity, generally 0.5 to 0.00). In the solid phase polycondensation of the 65 dL / g) polyester prepolymer particles, the temperature is raised stepwise so that the particles do not fuse with each other, and the polycondensation reaction rate is not necessarily improved. Also, melt polycondensation equipment for obtaining a medium molecular weight prepolymer is more expensive than equipment for obtaining low molecular weight prepolymers and is not always a satisfactory method.

  Patent Document 5 discloses a continuous crystallization apparatus for a polyester material in which an ejection vortex bed having mixing characteristics and a fluidized bed having piston flow properties are connected to each other. The purpose is mainly to form a polyester having a low crystallization rate, such as a copolyester, into granules having uniform crystallinity and no agglomeration, and no solid-state polymerization apparatus as a subsequent process is described.

Patent Document 6 discloses a continuous multistage heat treatment apparatus characterized in that a fluid passage is formed in a separation wall between a plurality of fluidization regions, and the first region occupies most of the entire volume. Yes. However, as in Patent Document 5, there is no description of a solid phase polymerization apparatus as a subsequent process.
Japanese Patent No. 3626758 JP 2004-67997 A JP-T-2004-537622 US Pat. No. 5,408,035 Japanese Patent No. 3073498 Special Table 2005-500928

  An object of the present invention is to provide a heat treatment apparatus for polyester particles suitable for carrying out crystallization and solid-phase polycondensation by raising the temperature stepwise, in particular, a high molecular weight by heat treating a low molecular weight polyester prepolymer. It is an object of the present invention to provide a heat treatment apparatus for polyester particles suitable for obtaining a polyester.

  As a result of studying the above problems, the present inventor has found that a fluidized bed is effective as a crystallization apparatus for polyester particles, and that a moving bed is effective for solid phase polycondensation. In addition, before the solid-phase polycondensation of the crystallized polyester particles at a high temperature, a solid-phase polycondensation reaction at a high temperature is performed by preliminarily performing a short-term solid-phase polycondensation at a temperature lower than the solid-phase polycondensation temperature. It has been found that the speed increases and the overall reaction time can be shortened. As a result of further studies, it has been found that it is effective to raise the temperature in a short time using a fluidized bed after the preliminary solid-phase polycondensation described above, and the present invention has been achieved.

  That is, the gist of the present invention is an apparatus for heat treatment of polyester particles, and 1) a first fluidized bed, 2) a first moving bed, 3) a second fluidized bed, 4) a second moving along the flow of the particles. Heat treatment for continuous solid-phase polycondensation of polyester particles characterized in that the beds are arranged in this order, and the internal volume of the second moving bed is twice or more the internal volume of the first moving bed Exists in the device.

  Furthermore, the following apparatus examples are given as preferred embodiments of the present invention.

  The first fluidized bed has a fluidized bed region having complete mixing properties arranged on the upstream side and a fluidized bed region having plug flow properties arranged on the downstream side, and the heat treatment apparatus for the polyester particles .

  The heat treatment apparatus for polyester particles, wherein the second fluidized bed is a fluidized bed having plug flow properties.

  The first moving bed and / or the second moving bed has a mechanism for circulating an inert gas, and has a gas inlet at the lower part of the moving bed and a gas outlet at the upper part, respectively. Heat treatment equipment for polyester particles.

  The first moving bed and / or the second moving bed has a plurality of regions divided in the vertical direction, and has a gas inlet at a lower portion of each region and a gas outlet at an upper portion thereof. Heat treatment equipment for polyester particles.

  The polyester characterized in that the first moving bed and / or the second moving bed has a plurality of regions divided in the vertical direction, and has a gas inlet and a gas outlet in the transverse direction of each region. Particle heat treatment equipment.

  The polyester particle heat treatment apparatus has a mechanism for removing organic substances and / or water in the gas in the flow path of the inert gas.

  The polyester particle heat treatment apparatus has a mechanism for condensing and recovering organic substances and / or water in the gas in a flow path of the inert gas.

  The polyester particle heat treatment apparatus, which has a mechanism for burning organic substances in the gas and a mechanism for absorbing water in the gas in this order in the flow path of the inert gas.

  A mechanism for condensing and recovering organic substances and / or water in the gas, a mechanism for burning the organic substances in the gas, and a mechanism for absorbing water in the gas in this order in the distribution path of the inert gas. A heat treatment apparatus for the polyester particles, comprising:

  The first moving bed and / or the second moving bed has a mechanism for flowing the inert gas, and a flow of the inert gas flowing through at least the uppermost region, having a plurality of regions divided in the vertical direction. A mechanism for condensing and collecting organic matter and / or water in the gas in the path, and a mechanism for combusting the organic matter in the gas in a flow path of an inert gas flowing through at least the lowermost region; and The polyester particle heat treatment apparatus has a mechanism for absorbing water in the gas in this order.

  An apparatus for treating polyester particles, comprising a mechanism for condensing and recovering an organic substance in an inert gas and using at least a part of the organic substance as a raw material for producing polyester particles.

  Another gist of the present invention is that the intrinsic viscosity is 0.03 to 0 on the first moving bed by using the heat treatment apparatus described above, and polyester particles having an intrinsic viscosity of 0.18 to 0.40 dL / g. The present invention resides in a multistage solid phase polycondensation method for polyester particles, characterized in that solid phase polycondensation is carried out until it increases by 10 dL / g, and further, solid phase polycondensation is carried out in a second moving bed to an intrinsic viscosity of 0.70 dL / g or more.

  In addition, the gist of the present invention is to condense and recover at least a part of the organic matter produced as a by-product with the solid phase polycondensation using the heat treatment apparatus described above, and use it as a raw material for producing polyester particles. It exists also in the multistage solid-phase polycondensation method of the polyester particle characterized by these.

  The apparatus of the present invention makes it possible to raise the temperature stepwise, and solid phase polycondensation can be performed at high speed without fusing the low molecular weight polyester prepolymer particles. As a result, the melt polycondensation process can be relatively simplified, leading to cost reduction of the entire polyester production apparatus. The resulting high molecular weight polyester has applications in a wide range of fields such as fibers, fabrics, molding resins and beverage bottles.

  Hereinafter, the present invention will be described in detail. The present invention is a heat treatment apparatus for polyester particles, wherein 1) a first fluidized bed, 2) a first moving bed, 3) a second fluidized bed, 4) a second moving bed, A heat treatment apparatus for continuously solid-phase polycondensation of polyester particles arranged in this order and characterized in that the internal volume of the second moving bed is at least twice the internal volume of the first moving bed .

  FIG. 1 shows an example of a heat treatment apparatus of the present invention. In the figure, A is the first fluidized bed, B is the first moving bed, C is the second fluidized bed, D is the second moving bed, and E is the cooler. G-G ′ indicates an inert gas flow path. Thick line lines 1, 2, 3, 4, 5, 6 indicate the flow of polyester particles.

  In FIG. 1, the polyester particles obtained by melt polycondensation are quantitatively and continuously introduced into the first fluidized bed A having complete mixing properties via the line 1 from the upstream process. The first fluidized bed A is maintained at 100 to 200 ° C., preferably 150 to 190 ° C., and the polyester particles are heat-treated for 2 to 30 minutes for crystallization. The first fluidized bed A has a perforated plate and, if necessary, a stirring mechanism, and is heated and fluidized by an inert gas introduced from outside (not shown). Nitrogen is usually used as the inert gas, and the linear velocity of the gas for fluidization depends on the size of the polyester particles, but is usually 0.3 to 2 m / second, preferably 0.5 to 1. About 5m / sec is selected. The first fluidized bed A has a mechanism capable of discharging particles quantitatively and continuously, such as an overflow gate and a rotary valve.

  FIG. 1A shows one fluidized bed (one reactor) with complete mixing, but as another example, it looks like one reactor but has two fluidized bed regions A reactor is mentioned. FIG. 6 is an example of a reactor having a fluidized bed region having complete mixing properties arranged on the upstream side and a fluidized bed region having plug flow properties arranged on the downstream side.

  In this specification, “having complete mixing” means not only in the so-called “ideal complete mixing” state, but also the particles that have entered the reactor are rapidly and substantially uniformly dispersed throughout the reactor. The vector sum of the moving speeds of all the particles in the reactor is substantially 0 (zero) (the moving direction of the particles is substantially random). Usually, in a fluidized bed other than a fluidized bed having “plug flow property” described later, a fluidized bed having complete mixing property can be formed by sufficiently increasing the linear velocity of the fluidized gas. The structure and conditions of the fluidized bed can be appropriately selected within the range in which the effects of the present invention can be obtained according to the size of the reactor used, the physical properties of the polyester particles, and the like.

  Further, in the present specification, “having plug flow property” means not only the state of so-called “ideal extrusion flow (also referred to as“ piston flow ”) but also that the residence time of particles in the reactor is substantially constant. And a vector sum of the moving speeds of all particles in the reactor from the inlet to the outlet of the particles. It is said to be substantially parallel to the vector that heads. Usually, in a fluidized bed, a partition plate is provided in the flow direction, the flow direction is inclined downward, and / or the flow direction of the fluidized gas is changed from the inlet to the outlet of the particles. A fluidized bed having plug flow properties can be formed. The structure and conditions of the fluidized bed can be appropriately selected within the range in which the effects of the present invention can be obtained according to the size of the reactor used, the physical properties of the polyester particles, and the like.

  In FIG. 6, a1 is a horizontal perforated plate, a2 is an inclined perforated plate, b is a stirring mechanism, and c and d are partition plates. The former stage (left reaction chamber divided by the partition plate c) forms a fluidized bed region having complete mixing properties, and the latter stage (right reaction chamber) forms a fluidized bed region having plug flow properties. Such a fluidized bed reactor is effective in avoiding the fusion of the polyester particles.

  The polyester particles discharged from the first fluidized bed A are quantitatively and continuously introduced into the first moving bed B via the line 2. The first moving bed B is maintained at 190 to 230 ° C., preferably 200 to 215 ° C., the polyester particles are heat-treated for 1.5 to 5 hours, and the first stage solid phase polycondensation is performed. The intrinsic viscosity of the polyester particles provided to the first moving bed B is preferably 0.18 to 0.40 dL / g, and the intrinsic viscosity of the polyester particles by solid phase polycondensation is at least 0.03 dL / g, preferably Is processed so as to increase by about 0.05 to 0.10 dL / g. The first moving bed B has a mechanism for discharging the particles quantitatively and continuously, such as a rotary valve, in the lower part, and the polyester particles move downward from above. On the other hand, the inert gas moves from the bottom to the top (countercurrent), from the top to the bottom (cocurrent flow), or from side to side (horizontal direction), with the gas inlet at the bottom and the gas outlet at the top. It is preferable to have. Organic substances and water mainly composed of glycols by-produced by solid phase polycondensation are discharged to the outside (G ′) of the first moving bed B along with the inert gas introduced from the outside G.

  The polyester particles discharged from the first moving bed B are quantitatively and continuously introduced into the second fluidized bed C via the line 3. The second fluidized bed C has a function of rapidly raising the temperature of the polyester particles obtained by the first stage solid phase polycondensation, and is preferably a fluidized bed having plug flow properties. The second fluidized bed C has a perforated plate and, if necessary, a stirring mechanism, and the polyester particles are kept in a fluidized state by an inert gas introduced from the outside (not shown). Meanwhile, the polyester particles are heated to 230-245 ° C. This temperature is 15 ° C. or more higher than the temperature of the first stage solid phase polycondensation, and is the same as the temperature of the subsequent second stage solid phase polycondensation, or 1 to 8 ° C., preferably 3 to 6 ° C. higher. Controlled. This is because it is possible to make it difficult for the polyester particles to fuse with each other in the second moving bed. The residence time of the second fluidized bed C is usually controlled to be within 30 minutes, preferably within 25 minutes, and more preferably within 20 minutes. The effect of the multistage solid phase polycondensation of the present invention is further increased by rapidly raising the temperature with such a residence time. Similar to the first fluidized bed A, the second fluidized bed C has a mechanism capable of discharging particles quantitatively and continuously, such as an overflow gate and a rotary valve.

  The polyester particles discharged from the second fluidized bed C are quantitatively and continuously introduced into the second moving bed D via the line 4, where the second stage solid phase polycondensation is performed. The temperature of the second stage solid phase polycondensation is preferably 15 ° C. or higher and 250 ° C. or lower than the temperature of the first stage solid phase polycondensation. The internal volume of the second moving bed D is set in the range of 2 times or more, preferably 3 to 8 times that of the first moving bed B. It is a reaction space necessary for giving sufficient residence time to the polyester particles. The residence time depends on the temperature, but is usually selected from the range of 5 to 50 hours, preferably 8 to 20 hours. The second moving bed D has the same mechanism as the first moving bed B, and the polyester particles move downward from above. The polyester particles undergo a heat treatment for a predetermined residence time and undergo solid phase polycondensation, and the intrinsic viscosity becomes 0.70 dL / g or more, preferably 0.80 dL / g or more. In addition, organic substances and water mainly composed of glycols by-produced by solid-phase polycondensation are discharged from G ′ to the outside of the second moving bed D along with the inert gas introduced from G. Flow contact). In some cases, an inert gas can be introduced from G ', brought into co-current contact with the polymer particles and discharged from G, but preferably has a gas inlet at the bottom and a gas outlet at the top. The inert gas discharged from the first moving bed B and the second moving bed D is independently or combined and separately led to a gas treatment process, and the contained organic matter and / or water is condensed and recovered. It is preferable to do this. The inert gas after the organic substance and / or water is condensed and recovered can be circulated in the system and reused. Similar to the first moving bed B, the second moving bed D has a mechanism for discharging particles quantitatively and continuously, such as a rotary valve, in the lower part, and the polyester particles move downward from above.

  The polyester particles discharged from the second moving bed D are introduced into the cooler E via the line 5. Cooling is necessary for stabilizing the quality of the polyester particles (product) subjected to solid phase polycondensation. Although the structure of the cooler E is not limited, for example, a fluidized bed having a plug flow property is used, and it is preferable to cool to near room temperature with a residence time of about 10 to 30 minutes. The cooled polyester particles are conveyed through a line 6 to a commercialization process (not shown).

  FIG. 2 shows another example of the heat treatment apparatus of the present invention. In the figure, A1 is a fluidized bed region having complete mixing properties, A2 is a fluidized bed region having plug flow properties, B is a first moving bed, C is a second fluidized bed, D is a second moving bed, and E is a cooler. Respectively.

  In FIG. 2, A1 is a fluidized bed arranged on the upstream side along the flow of the polyester particles, A2 is a fluidized bed arranged on the downstream side, and by joining A1 and A2 in this way, One fluidized bed A is formed. The structure of A1 includes a perforated plate, a stirring mechanism, a partition plate, and the like, and is heated and fluidized by an inert gas introduced from outside (not shown). As the structure of A2, one having plug flow property is preferable. Usually, an inert gas is introduced into A2. The movement of the polyester particles can be assisted by appropriately selecting the gas flow direction. The movement of the polymer particles can also be assisted by inclining the flow direction downward.

  As an advantage of crystallizing the melt-polycondensed polyester particles in such a two-step process (A1 + A2), it is possible to sufficiently crystallize particles having a short residence time in A1 and insufficient crystallization with A2. What can be done. In the crystallization of polyester particles, when a moving bed or a fluidized bed having plug flow properties is installed in the first stage, amorphous particles are unevenly distributed in the apparatus, and as a result, fusion of polyester particles is likely to occur. So it is disadvantageous. An embodiment in which a fully mixed fluidized bed is provided in the first stage is preferable.

  FIG. 3 is an example showing the internal structure of the second moving bed D of the present invention. In the figure, D1 represents the first region of the second moving bed, D2 represents the second region of the second moving bed, and D3 represents the third region of the second moving bed. G1-G1 ', G2-G2', and G3-G3 'indicate inert gas flow paths to the regions D1, D2, and D3, respectively. In FIG. 3, (1) shows an aspect in which the polyester particles and the inert gas are in countercurrent contact, and (2) shows an aspect in which the polyester particles and the inert gas are in contact with each other in a perpendicular direction. In (2), a gas inlet and a gas outlet are installed in the transverse direction of each region D1, D2, D3.

  In FIG. 3, the second moving bed D is divided into three regions in the vertical direction, and has a structure in which a flow path for introducing and discharging an inert gas is provided independently for each division. The polymer particles stay in the second moving bed D for a long time, and a large amount of glycols and water are by-produced. The amount of by-product is not uniform in the vertical direction of the second moving bed D, and usually the amount of by-product glycol is higher toward the upper side. Therefore, by setting the second moving bed D to the structure shown in FIG. 3, the amount of inert gas introduced can be controlled independently in each region, and at the same time, inert gases having different by-product glycol concentrations can be used. There is an advantage that each can be collected independently. In some cases, the temperature of the region can be controlled independently for each section.

  Although FIG. 3 divides the moving floor into three regions in the vertical direction, the number of divisions is not limited and can be divided into 2 to 6 as necessary. The size of each region may be the same or different. The inert gas flow paths may be independent for each region, but some of them may be combined. The first moving bed B can be divided into a plurality of regions in the same manner as the second moving bed D.

  FIG. 4 is an example of a block diagram showing a flow path when an inert gas circulates in the polyester heat treatment apparatus of the present invention. In the figure, A, B, C, D, E and lines 1, 2, 3, 4, 5, 6 are the same as those in FIG. The inert gas discharged from the first fluidized bed A, the first fluidized bed B, the second fluidized bed C, and the second fluidized bed D combines them and removes organic substances and / or water via the line 8. It is led to a condensing device F which is a mechanism, particularly a condensing and collecting mechanism which is a preferred embodiment. Condensed components mainly composed of glycol and water are led to a glycol recovery step from the line 10, and the uncondensed inert gas forms a circulation flow path that is supplied again to each device via the line 9. An inert gas is newly supplied from the line 7 and a part of the circulating gas is discharged outside (not shown). FIG. 4 shows the entire flow path through which the inert gas circulates, and a valve for opening and closing the flow path is omitted. Therefore, it does not necessarily mean that an inert gas is circulating in all of the flow paths.

  FIG. 5 is another example of a block diagram showing a flow path through which an inert gas circulates in the polyester heat treatment apparatus of the present invention. In the figure, H indicates a heat exchanger. It is an example of the optimization design of a heat balance in consideration of the temperature and heat capacity of the inert gas discharged | emitted from each process.

  FIG. 6 is an example of a reactor having a fluidized bed region having complete mixing properties arranged on the upstream side and a fluidized bed region having plug flow properties arranged on the downstream side.

  FIG. 7 is another example of an apparatus diagram for treating the inert gas discharged from the first moving bed and / or the second moving bed. In the figure, J is an ethylene glycol scrubber, K is a catalyst layer, and L is a desiccant layer. The inert gas discharged from the gas discharge channel G ′ comes into counter-current contact with the cold ethylene glycol dripping from the top of the scrubber J, and the organic matter and / or water contained in the gas is condensed. Ethylene glycol containing condensate is withdrawn from the scrubber J via line 11, part of which is led to the purification process via line 14, and the remainder is circulated.

  The ethylene glycol obtained in the purification step is stored in a tank (not shown) and can be recycled as a raw material for producing polyester particles. Ethylene glycol is newly supplied from the line 12, is cooled by the heat exchanger H together with the circulating ethylene glycol, and is supplied to the upper portion of the scrubber J through the line 13. The inert gas from which the condensed components have been removed is introduced into the catalyst layer K via the line 15 and is combusted by the air supplied from the line 16. The inert gas after the combustion treatment passes through the desiccant layer L to remove moisture, and a purified inert gas is obtained via the line 18. The purified inert gas is circulated and used in the inert gas introduction channel G. According to the apparatus of FIG. 7, compared with the apparatus of FIG.4 and FIG.5, the removal of a condensing component (organic substance and / or water) is performed efficiently, and it can circulate and utilize as inert gas with higher purity. it can.

  FIG. 8 is an example of an apparatus diagram for processing the inert gas discharged from the second moving bed in the vertical direction. As shown in FIG. 8, the second moving bed D is divided into two upper and lower regions, and the inert gas discharged from the upper region D1 is treated with the ethylene glycol scrubber J. Because the amount of by-produced ethylene glycol is large, emphasis should be placed on its recovery and in line with its purpose. On the other hand, the inert gas discharged from the lower region D2 of the second moving bed D is processed by the catalyst layer K and the desiccant layer L. This is an apparatus arrangement suitable for circulating an inert gas having a high purity. On the other hand, although not shown, the first moving bed B can also be divided into two upper and lower regions B1 and B2. In this case, since the amount of by-produced ethylene glycol is large in any region, treatment with ethylene glycol scrubber J is preferable.

  Moreover, since the organic substance condensed and recovered from the inert gas as described above contains the diol used in producing the polyester particles as a main component, a part of the raw material for producing the polyester particles. Can be used as In that case, it is preferable that the heat processing apparatus of this invention has a mechanism for using the organic substance condensed and collect | recovered from inert gas as a part of raw material for manufacturing a polyester particle. The method for using the recovered organic substance as a part of the raw material is not particularly limited. For example, in the method for producing a polyester prepolymer described later, it may be used as a part of the raw material for preparing the raw material slurry. By using the recovered organic substance as a part of the raw material for producing the polyester particles, the basic unit for producing the polyester obtained by the solid phase polycondensation method of the present invention is improved, which is more preferable.

  As described above, in the heat treatment apparatus for polyester particles of the present invention, 1) a first fluidized bed, 2) a first moving bed, 3) a second fluidized bed, 4) a second moving bed, a fluidized bed dividing mechanism, a cooler, The auxiliary equipment such as the condensing device, the inert gas circulation channel, and the heat balance optimization design has been described. Next, the polyester particles applied to the device, the heat treatment step including solid phase polycondensation of the polyester particles, etc. Hereinafter, the polyester particles obtained by melt polycondensation are particularly referred to as “polyester prepolymer particles”.

  In the present invention, polyester prepolymer particles obtained by melt polycondensation are heat-treated in an inert gas atmosphere or under reduced pressure to proceed with polycondensation (solid phase polycondensation) in a solid state to efficiently produce a polyester suitable for molding. When producing, use a low molecular weight prepolymer as a prepolymer, perform solid phase polycondensation at a relatively low temperature, then raise the temperature by 15 ° C. or higher until a polyester having a predetermined molecular weight is obtained at a relatively high temperature. It is characterized by performing condensation. By doing so, a higher polycondensation reaction rate can be obtained in the high molecular weight region than when solid-phase polycondensation is performed at a relatively high temperature from the beginning. The reason is not clear, but is estimated as follows.

  That is, when crystallized at a low molecular weight, the mobility of the polyester molecular chain decreases due to the formation of a crystal structure, and some terminal groups are inactivated, but especially when crystallized at a low molecular weight. Since the absolute value of the number of terminal groups to be inactivated increases, the polycondensation reaction rate decreases in the latter half of the solid phase polycondensation. On the other hand, by giving a heat treatment of a temperature difference of 15 ° C. or more in the middle, the solid state is maintained, but the crystal is melted and recrystallized, and an amorphous region having a large number of end groups is formed again. Therefore, it is presumed that some of the inactivated end groups regain activity and the polycondensation reaction rate increases.

  In the present invention, the heat treatment step includes a crystallization step, a first stage solid phase polycondensation step, a temperature raising step, a second stage solid phase polycondensation step, etc., and these are solid in an atmosphere exceeding normal temperature. It is the process of processing a shaped polyester prepolymer particle. In the present invention, intrinsic viscosity is used as an index of molecular weight.

<Polyester prepolymer>
The manufacturing method of the polyester prepolymer used for this invention is not specifically limited, Usually, what is necessary is just to follow the conventional manufacturing method of polyester. Specifically, it is usually produced by subjecting a dicarboxylic acid and / or its ester-forming derivative and a diol to melt polycondensation using a polycondensation catalyst through an esterification reaction and / or a transesterification reaction. . Specifically, for example, dicarboxylic acid and diol are charged into a slurry preparation tank, stirred and mixed to obtain a raw slurry, and water generated by the reaction is distilled under normal pressure to pressure and heating in an esterification reaction tank. After the esterification reaction while leaving, the polyester low molecular weight product (oligomer) as the resulting esterification reaction product is transferred to a polycondensation tank and melted by using a polycondensation catalyst under reduced pressure and heating. A polyester prepolymer is obtained by condensation.

  It does not restrict | limit especially as a polycondensation reaction catalyst of a polyester prepolymer, A well-known catalyst can be used. For example, germanium compounds such as germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, germanium tetraethoxide, germanium tetra-n-butoxide, antimony compounds such as antimony trioxide, antimony pentoxide, antimony acetate, methoxyantimony, Titanium compounds such as tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, titanium oxalate, and titanium potassium oxalate are used alone or in combination. Of these, titanium compounds are preferably used because of their high polycondensation reaction activity. The usage-amount of a catalyst is 1-400 mass ppm normally with respect to the polyester prepolymer obtained.

  In addition, phosphorus compounds such as normal phosphoric acid, normal phosphoric acid alkyl ester, ethyl acid phosphate, triethylene glycol acid phosphate, phosphorous acid, and phosphorous acid alkyl ester can be used as stabilizers. The amount used is preferably 1 to 1000 ppm by mass, particularly preferably 2 to 200 ppm by mass, based on the polyester prepolymer obtained.

  Furthermore, compounds of alkali metals and alkaline earth metals such as lithium acetate, sodium acetate, potassium acetate, magnesium acetate, magnesium hydroxide, magnesium alkoxide, magnesium carbonate, potassium hydroxide, calcium hydroxide, calcium acetate, calcium carbonate are also mentioned. It can also be used with a polycondensation catalyst.

  When the dicarboxylic acid component is an ester-forming derivative of dicarboxylic acid, such as dimethyl terephthalate, having an appropriate melting point, it can be melted without being slurry with diol and then subjected to transesterification with diol. .

  In addition, these are made by any one or more methods of a continuous type, a batch type, and a semi-batch type, and the esterification reaction tank (or transesterification reaction tank) and the melt polycondensation reaction tank are each made up of a single stage or multiple stages. Also good.

  Examples of the process for producing a polyester prepolymer to which the present invention can be particularly preferably applied include a process for producing polyethylene terephthalate and / or polybutylene terephthalate. That is, in the production process, the main component of dicarboxylic acid is terephthalic acid and / or dimethyl terephthalate, and the main component of diol is ethylene glycol and / or 1,4-butanediol. Here, the “main component” means that terephthalic acid accounts for 85 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more of the total dicarboxylic acid component, and ethylene glycol or 1,4-butanediol is It means to occupy 85 mol% or more, preferably 90 mol% or more of the total diol component.

  Examples of dicarboxylic acid components other than terephthalic acid include phthalic acid, isophthalic acid, dibromoisophthalic acid, sodium sulfoisophthalic acid, phenylenedioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and 4,4′-diphenyletherdicarboxylic acid. 4,4'-diphenyl ketone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid and other aromatic dicarboxylic acids, hexahydroterephthalic acid , Alicyclic dicarboxylic acids such as hexahydroisophthalic acid, and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid , Etc. and their ester forms Sex derivatives.

  In addition to diethylene glycol, diol components other than ethylene glycol and 1,4-butanediol include, for example, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, 2-ethyl. Aliphatic diols such as 2-butyl-1,3-propanediol, polyethylene glycol, polytetramethylene ether glycol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, Cycloaliphatic diols such as 4-cyclohexanedimethylol, 2,5-norbornane dimethylol, and xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4′-hydroxy) Phenyl) propane, 2,2-bis (4′-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, and the like, and An ethylene oxide adduct or a propylene oxide adduct of 2,2-bis (4′-hydroxyphenyl) propane may be mentioned.

  The polyester prepolymer obtained by the melt polycondensation reaction is supplied to a die head connected to the melt polycondensation reaction tank via a pipe and / or a gear pump and / or a filter, and from a plurality of die holes provided at the tip of the die. , Discharged in the form of strands or drops. The discharged polyester prepolymer is granulated by, for example, a strand cutter.

  The polyester prepolymer particles used in the present invention usually have an average particle size of preferably 0.5 to 3.0 mm, more preferably 0.6 mm or more, and particularly preferably 0.65 mm or more, while 2.0 mm or less. Is more preferably 1.8 mm or less, and particularly preferably 1.6 mm or less. If the average particle size is less than 0.5 mm, the amount of fine powder increases when the particles are formed, and trouble during transfer is likely to occur in the subsequent steps. When the average particle diameter exceeds 3 mm, the required solid phase polycondensation time tends to be very long regardless of the effect of the present invention.

  Here, the average particle size of the particles is determined by preparing an integrated distribution curve by the dry screening test method described in JISK0069 and taking the value when the integrated percentage is 50% as the average particle size.

  The intrinsic viscosity of the polyester prepolymer used in the present invention is 0.18 to 0.40 dL / g. The lower limit is preferably 0.20 dL / g, and the upper limit is preferably 0.38 dL / g, particularly preferably 0.35 dL / g. If it is less than the lower limit, fine powder is likely to be generated when it is formed into particles, and even if the effects of the present invention are taken into account, the necessary solid phase polycondensation time becomes very long, which is not preferable. When the upper limit is exceeded, expensive equipment for performing high-viscosity liquid stirring and high-vacuum reaction in the melt polycondensation step is required, and the effects of the present invention are diminished.

  The terminal carboxyl group concentration of the polyester prepolymer of the present invention is preferably 100 equivalents / ton or less. More preferably, it is 70 equivalent / ton or less, More preferably, it is 40 equivalent / ton or less, Most preferably, it is 20 equivalent / ton or less. If it exceeds 100 equivalents / ton, the polycondensation reaction rate tends to decrease in the subsequent solid-phase polycondensation step.

<Heat treatment process>
The polyester prepolymer particles obtained as described above are heat-treated in a solid state and subjected to solid phase polycondensation to a predetermined intrinsic viscosity by the method of the present invention. The heat treatment step in the present invention is divided into a plurality of steps such as crystallization, first stage solid phase polycondensation, temperature increase, and second stage solid phase polycondensation. The present invention is an apparatus suitable for performing the above heat treatment step in a continuous manner. The intrinsic viscosity of the polyester obtained in the present invention is preferably 0.70 dL / g or more, particularly preferably 0.80 dL / g or more. When it is less than 0.70 dL / g, the effect of increasing the solid phase polycondensation reaction rate of the present invention does not lead to an improvement in productivity.

  The solid phase polycondensation step of the heat treatment step of the present invention is carried out in a moving bed over at least two stages. The first stage solid phase polycondensation temperature is 190 to 230 ° C, and the lower limit is preferably 195 ° C, more preferably 205 ° C. The upper limit is preferably 220 ° C, more preferably 215 ° C. When it is lower than 190 ° C., the solid phase polycondensation rate in the first stage is reduced, and the load of the second stage solid phase polycondensation, which is a subsequent process, is increased. If it exceeds 230 ° C., the temperature of the second stage exceeds 250 ° C., and the polyester particles are likely to be fused with each other. Further, as described above, the temperature of the second stage solid phase polycondensation is set to a temperature that is 15 ° C. or more higher than the first stage solid phase polycondensation temperature and 250 ° C. or less. If it is less than 15 ° C., the effect of improving the solid phase polycondensation reaction rate of the present invention cannot be obtained.

  The increase in intrinsic viscosity in the first stage is 0.03 dL / g or more, preferably 0.05 dL / g or more. If it is less than 0.03 dL / g, the effect of improving the solid phase polycondensation reaction rate in the second stage cannot be sufficiently obtained. The upper limit of the increase in intrinsic viscosity in the first stage may be set so that the entire heat treatment step takes the shortest time and / or the input heat amount is minimized, and is usually 0.30 dL / g, preferably It is about 0.10 dL / g.

  Further, the difference between the intrinsic viscosity of the polyester at the outlet of the first stage solid phase polycondensation (first moving bed B) and the intrinsic viscosity of the polyester at the inlet of the second stage solid phase polycondensation (second moving bed D) is usually 0. It is preferably .10 dL / g or less, more preferably 0.05 dL / g or less. When the difference in intrinsic viscosity is within this range, the effect of the present invention obtained by raising the temperature from the first stage solid phase polycondensation to the second stage solid phase polycondensation in a short time is sufficiently exhibited. preferable.

  In order to smoothly perform the transition from the first stage solid phase polycondensation to the second stage solid phase polycondensation, a temperature raising step including the second fluidized bed C is provided between the first stage and the second stage. The temperature is preferably 250 ° C. or lower. This is because fusion of polymer particles in the second stage solid phase polycondensation hardly occurs.

  In the method of the present invention, the step of crystallizing the substantially amorphous polyester prepolymer is performed in the first fluidized bed before the first stage solid phase polycondensation step. Crystallization can reduce the fusion of the polyester particles in the subsequent solid phase polycondensation step. The temperature of the first fluidized bed is 100 to 200 ° C, preferably 150 to 190 ° C. If it is less than 100 ° C., it takes a long time to crystallize the prepolymer particles to such an extent that the prepolymer particles do not fuse with each other, thereby reducing the effect of the present invention. When it exceeds 200 ° C., the prepolymer particles tend to be fused with each other.

  The polyester obtained by the method of the present invention can be suitably used for forming raw materials such as fibers, films and bottles. In particular, after forming a preform by injection molding or extrusion molding, it can be made into a bottle used for beverage packaging or the like by stretch blow molding. Moreover, it can be made into a bottle by direct blow molding.

  Moreover, it can be used for various uses, such as a packaging material, by making into a film and a sheet | seat by extrusion molding and extending | stretching molding. Moreover, it can be set as a fiber by extrusion and drawing.

An example of the heat processing apparatus of this invention is shown. The other example of the heat processing apparatus of this invention is shown. It is an example which shows the internal structure of the 2nd moving bed D of this invention. It is an example of the block diagram which shows the circulation path of an inert gas in the heat processing apparatus of the polyester of this invention. It is another example of the block diagram which shows the circulation path of an inert gas in the heat processing apparatus of the polyester of this invention. It is an example of the reactor which combined the fluidized bed which has complete mixing property, and the fluidized bed which has plug flow property. It is another example of the apparatus figure which processes the inert gas discharged | emitted from a 1st moving bed and / or a 2nd moving bed. It is an example of the apparatus figure which divides and processes the inert gas discharged | emitted from a 2nd moving bed to an up-down direction.

Explanation of symbols

A: First fluidized bed A1: Fluidized bed with complete mixing A2: Fluidized bed with plug flowability B: First moving bed C: Second fluidized bed D: Second moving bed D1: Second of the second moving bed 1 area | region D2: 2nd area | region D3 of a 2nd moving bed: 3rd area | region E of a 2nd moving bed E: Cooling machine F: Condensing apparatus GG ', G1-G1', G2-G2 ', G3-G3': Inert gas flow path H: heat exchanger

Line 1: Flow path of polyester prepolymer particles 2: Flow path of crystallized polyester prepolymer particles 3: Flow path of polyester particles after first stage solid phase polycondensation 4: Rapidly heated first stage Polyester particle flow line 5 after the solid phase polycondensation: Polyester particle flow line 6 after the second stage solid phase polycondensation 6: Product flow line 7: New inert gas supply flow line 8: Solid Phase polycondensation exhaust gas flow line 9: Inert gas circulation flow line 10: Condensed component discharge flow path

a1: Horizontal perforated plate a2: Inclined perforated plate b: Stirring mechanism c, d: Partition plate

J: ethylene glycol scrubber K: catalyst layer L: desiccant layer line 11: ethylene glycol scrubber extraction passage line 12: ethylene glycol new supply passage line 13: ethylene glycol circulation passage line 14: ethylene glycol purification passage line 15: Ethylene glycol scrubber inert gas recovery flow path line 16: Air supply flow path line 17: Inert gas flow path line 18 after combustion treatment 18: Purified inert gas flow path

Claims (16)

  A heat treatment apparatus for polyester particles, wherein 1) a first fluidized bed, 2) a first moving bed, 3) a second fluidized bed, and 4) a second moving bed are arranged in this order along the flow of the particles. A heat treatment apparatus for continuously solid-phase polycondensing polyester particles, characterized in that the internal volume of the second moving bed is twice or more the internal volume of the first moving bed.   The first fluidized bed has a fluidized bed region having perfect mixing properties arranged on the upstream side and a fluidized bed region having plug flow properties arranged on the downstream side. Heat treatment equipment for polyester particles.   The heat treatment apparatus for polyester particles according to claim 1 or 2, wherein the second fluidized bed is a fluidized bed having plug flow properties.   The first moving bed and / or the second moving bed has a mechanism for circulating an inert gas, and has a gas inlet at a lower portion of the moving bed and a gas outlet at an upper portion, respectively. Item 4. The heat treatment apparatus for polyester particles according to any one of Items 1 to 3.   The first moving bed and / or the second moving bed has a plurality of regions divided in the vertical direction, and has a gas inlet at a lower portion of each region and a gas outlet at an upper portion thereof. Item 5. The heat treatment apparatus for polyester particles according to any one of Items 1 to 4.   The first moving bed and / or the second moving bed has a plurality of regions divided in the vertical direction, and has a gas inlet and a gas outlet in a transverse direction of each region. The heat processing apparatus of the polyester particle of any one of 1-4.   The heat treatment apparatus for polyester particles according to any one of claims 4 to 6, wherein the inert gas flow path has a mechanism for removing organic substances and / or water in the gas.   The polyester particle heat treatment apparatus according to any one of claims 4 to 6, further comprising a mechanism for condensing and collecting organic substances and / or water in the gas in a flow path of the inert gas.   The flow path of the inert gas has a mechanism for burning organic substances in the gas and a mechanism for absorbing water in the gas in this order, according to any one of claims 4 to 6. The heat processing apparatus of the polyester particle of description.   A mechanism for condensing and recovering organic substances and / or water in the gas, a mechanism for burning the organic substances in the gas, and a mechanism for absorbing water in the gas in this order in the distribution path of the inert gas. It has, The heat processing apparatus of the polyester particle of any one of Claims 4-6 characterized by the above-mentioned.   The first moving bed and / or the second moving bed has a mechanism for flowing the inert gas, and a flow of the inert gas flowing through at least the uppermost region, having a plurality of regions divided in the vertical direction. A mechanism for condensing and collecting organic matter and / or water in the gas in the path, and a mechanism for combusting the organic matter in the gas in a flow path of an inert gas flowing through at least the lowermost region; and The heat treatment apparatus for polyester particles according to any one of claims 4 to 10, further comprising a mechanism for absorbing water in the gas in this order.   The organic substance in the inert gas is condensed and recovered, and at least a part of the organic substance is used as a raw material for producing polyester particles, and has a mechanism for using any one of claims 8, 10 and 11 The processing apparatus of the polyester particle of Claim 1.   The polyester according to claim 1, wherein the first fluidized bed is used as a crystallization step, the first moving bed and the second moving bed are used as a solid phase polycondensation step, and the second fluidized bed is used as a rapid heating step. Particle heat treatment equipment.   The temperature of the 2nd moving bed is 15 degreeC or more higher than the temperature of a 1st moving bed, and is 250 degrees C or less, The heat processing apparatus of the polyester particle of Claim 13 characterized by the above-mentioned.   Using the heat treatment apparatus according to claim 1, polyester particles having an intrinsic viscosity of 0.18 to 0.40 dL / g are solidified on the first moving bed until the intrinsic viscosity increases by 0.03 to 0.10 dL / g. A method for multistage solid phase polycondensation of polyester particles, characterized in that phase polycondensation and solid phase polycondensation to an intrinsic viscosity of 0.70 dL / g or more in a second moving bed. 16. The multistage solid phase weight of polyester particles according to claim 15, wherein at least a part of organic substances by-produced by solid phase polycondensation is condensed and recovered, and used as a raw material for producing polyester particles. Condensation method.