JP4765748B2 - Method for producing polyester particles and method for producing polyester resin particles - Google Patents

Description

    The present invention relates to a method for producing polyester particles having a low degree of polymerization and polyester particles, and further relates to a method for producing polyester resin particles by solid-phase polycondensation of the polyester particles and polyester resin particles. Specifically, a method of cutting a polyester having a low polymerization degree after forming into a strand, a manufacturing method capable of stably forming polyester particles at high speed and a polyester having a substantially elliptical column shape Concerning particles. In addition, the polyester particles of a small particle size suitable for performing solid phase polycondensation at a high speed substantially having the shape of an elliptic cylinder have high polymerization degree and excellent processability by solid phase polycondensation. The present invention relates to a method for efficiently producing polyester resin particles and polyester resin particles.

    Polyesters typified by polyethylene terephthalate are excellent in mechanical properties, thermal properties, electrical properties, etc., so they are widely used in molded products such as fibers, films, sheets, bottles, etc. is doing. Polyesters used in these applications usually undergo esterification and / or transesterification of a dicarboxylic acid and / or its ester-forming derivative and a diol, followed by a melt polycondensation reaction and, if necessary, further solid-phase polycondensation. It is manufactured by.

    The polyester after the melt polycondensation reaction is usually granulated into particles having a particle size of about 1 mm to several mm in order to produce a product or to be used for solid phase polycondensation. As a granulation method, the melt-polycondensed polyester is usually discharged into a gas phase from a die plate having a plurality of pores (die holes) to form a strand, and then continuously cooled with water or after water cooling A method of cutting a strand with a rotating tooth and a fixed tooth having a rotation axis substantially orthogonal to the discharge direction (hereinafter sometimes referred to as a “strand cutting method”) is superior from the viewpoint of production efficiency. It has been implemented.

    However, a polyester having a relatively low intrinsic viscosity after the melt polycondensation reaction, such as a polyester having an intrinsic viscosity of about 0.3 dL / g or less, is used in order to use the polyester for a special purpose or to be used for solid phase polycondensation. In the case of granulation, it is known that since the melt viscosity is low, it is difficult to take a strand shape, and the strand after cooling is fragile, so that it is extremely difficult to granulate by the strand cutting method. Therefore, as a method for granulating such low intrinsic viscosity polyester, for example, Patent Documents 1 and 2 each propose a particle formation method other than the strand cut method.

    On the other hand, as a method for improving the strand cutting method, Patent Document 3 discloses that a plurality of strands of a molten thermoplastic resin material are extruded from a multi-die toward an inclined trough including a cooling water flow, brought into contact with the water in the trough, A method is described in which it is conveyed downward and rapidly cooled and then cut into particles with a strand cutter. Here, the linear velocity of the cooling water flow flowing down the trough is made larger than the linear velocity at which the strand is pushed out of the die, and it is newly formed by passing through a strand cutter connected directly to the end of the trough together with the strand. A method is disclosed for passing the strand end through the device along a path similar to the path taken by the preceding strand.

    The method disclosed here is an excellent method for making a thermoplastic resin material as a general molding material into particles (pelletization). However, in a polyester low polymer having a very low melt viscosity, strand running can be performed. It is not stable and it is difficult to form particles. In addition, in order to increase the solid-phase polycondensation reaction rate, particles to be subjected to solid-phase polycondensation may be required to have a small particle size. It is even more difficult to obtain.

    Patent Document 4 discloses a method of cutting a ribbon, gut, and sheet of a polyester having a low polymerization degree having an intrinsic viscosity of 0.32 to 0.40 dL / g after stretching at a draw ratio of less than 2 by roll-to-roll stretching. ing. In this method, as shown in FIGS. 1 and 2 of the document, when the intrinsic viscosity is 0.35 or less, the appropriate stretch ratio range is extremely narrow and cannot be used practically.

    Patent Document 5 discloses a method in which a molten polymer whose main component is polyester is formed into a pellet-shaped molding material, and the molten strand polymer discharged from the die is 0.10 to 0.50 in the atmosphere. It is described that after cooling for 2 seconds, it is contacted with cooling water and solidified into a pellet. However, the method disclosed herein cannot always obtain good pellets from low melt viscosity polyesters.

    Further, Patent Document 6 discloses cylindrical particles made of polyester having an internal viscosity of about 0.20 to 0.45 dL / g and a method for producing the same. In the method disclosed herein, the molten strands are passed through a narrow air gap, i.e., an air gap of less than about 4 inches (less than about 0.10 m), before quenching with a cooling medium. It is a requirement to obtain. However, with this method, it is difficult to stably granulate a low-viscosity polyester, and in particular, a substantially elliptic cylinder shape suitable for performing solid-phase polycondensation at a high speed in the present application is obtained. It is difficult to efficiently produce small-sized polyester particles having low viscosity polyester.

As described above, in the strand cutting method, there is no known specific method for efficiently converting low-polyester polyester.
Japanese Patent Application Laid-Open No. 51-066346 Japanese National Patent Publication No. 10-512510 Japanese Patent Publication No. 55-016806 Japanese Patent Publication No. 50-024359 Japanese Patent No. 29993369 WO2004 / 035284

    SUMMARY OF THE INVENTION In view of the above-mentioned background art, an object of the present invention is a method for efficiently producing polyester particles having a small particle diameter from a polyester having a low polymerization degree and a low melt viscosity by a strand cut method, and a polyester particle having a substantially elliptic cylinder shape. Is to provide. Further problems of the present invention are a method for producing polyester resin particles having a high degree of polymerization by solid-phase polycondensation of the polyester particles having a substantially elliptical column shape, and a polyester having a substantially elliptical column shape. It is to provide resin particles.

That is, the gist of the present invention is a polyester characterized in that the following steps (1) to (3) are sequentially performed, and the take-off speed ratio represented by the following formula of the strand polyester is 1.5 to 100: to exist in the manufacture how the particles.
(1) A step of discharging a molten polyester having a melt viscosity of 0.5 Pa · s to 50 Pa · s into a strand from a die hole having a hole diameter converted to a diameter of a circle having an area equal to the die hole area of 0.7 to 3 mm (2 ) A step of bringing the obtained strand-shaped polyester into contact with a cooling liquid fluid and guiding it to the cutter together with the liquid fluid (3) A step of cutting the strand-shaped polyester guided to the cutter

Other aspects of the present invention exist in the manufacture how the polyester resin particles, characterized in that the polyester particles having the shape of the substantially elliptical cylinder, subjected to solid phase polycondensation reaction.

  According to the present invention, polyester having a low degree of polymerization can be stably formed into particles, and in particular, polyester particles having a substantially small elliptical column shape and a uniform low degree of polymerization can be efficiently obtained. it can. In addition, if small particles with a specific shape are used, solid phase polycondensation can be carried out at a high speed in the solid phase polycondensation step, so that high polymerization suitable for packaging materials such as bottles and fibers for industrial materials. It is possible to efficiently obtain polyester resin particles having excellent processing characteristics at a high degree.

Hereinafter, although the structure of this invention is demonstrated, these are typical illustrations and are not limited to these.
The present invention relates to a method for efficiently producing polyester particles from a polyester having a low melt viscosity by a strand cutting method, and polyester particles having a substantially elliptical column shape, and also having a substantially elliptical column shape. The present invention relates to a method for producing polyester resin particles having a high degree of polymerization by solid-phase polycondensation of polyester particles and polyester resin particles having a substantially elliptic cylinder shape.

The method for producing polyester particles of the present invention (hereinafter sometimes referred to as a particle formation method) is a method of forming polyester particles having a low intrinsic viscosity from a polyester having a low polymerization degree and a low melt viscosity by a strand cutting method under predetermined operating conditions. In particular, it is a method for efficiently producing polyester particles having a substantially elliptic cylinder shape. That is, the method of the present invention sequentially comprises the following steps (1) to (3), and the take-up speed ratio represented by the following formula of the strand-like polyester is 1.5 to 100: It is a manufacturing method.
(1) A step of discharging a molten polyester having a melt viscosity of 0.5 Pa · s to 50 Pa · s into a strand from a die hole having a hole diameter converted to a diameter of a circle having an area equal to the die hole area of 0.7 to 3 mm (2 ) A step of bringing the obtained strand-shaped polyester into contact with a cooling liquid fluid and guiding it to the cutter together with the liquid fluid (3) A step of cutting the strand-shaped polyester guided to the cutter

  According to the particle formation method of the present invention, particles having a desired shape can be efficiently obtained from a polyester having a low polymerization degree after a melt polycondensation reaction having a melt viscosity at the time of discharge of 0.5 Pa · s to 50 Pa · s. Therefore, it is not necessary to increase the degree of polymerization in the melt polycondensation reaction, and expensive equipment for performing high viscosity liquid stirring and high vacuum reaction in the melt polycondensation step is not required. Further, according to the method of the present invention, it is possible to obtain small particle size particles substantially having an elliptical column shape, and when this small particle size polyester particle is subjected to solid phase polycondensation, Since the polycondensation rate can be increased, it is also a very useful method capable of efficiently producing polyester resin particles having a high degree of polymerization.

  Here, the melt viscosity is a complex viscosity when the polyester to be granulated is measured with a dynamic viscoelasticity measuring device (rheometer) at a shear rate of 10 rad / s at the temperature of the molten polyester when discharged from the die hole. That is.

The polyester used in the step (1) in the particle forming method of the present invention has a melt viscosity of 0.5 Pa · s to 50 Pa · s of the polyester when discharged from the die hole to the strand, that is, the strand-like polyester. The lower limit is preferably 1.5 Pa · s, more preferably 2.5 Pa · s. The upper limit is preferably 20 Pa · s, more preferably 10 Pa · s. If the melt viscosity of the polyester is less than the lower limit, the melt viscosity when discharged from the die hole is too low, and a stable strand may not be obtained and may break. When the upper limit is exceeded, the die hole diameter required to obtain polyester particles having a small particle size is small, so that it becomes difficult for the polyester to pass through the die hole and the stability of the operation is lacking. Further, in order to obtain a polyester having a high melt viscosity, expensive equipment for performing high viscosity liquid stirring and high vacuum reaction in the above-described melt polycondensation step is required, which is not preferable.
The melt viscosity of the polyester particles obtained by the granulation method of the present invention is equivalent to the melt viscosity of the strands.

  In the granulation method of the present invention, the strand take-off speed ratio (hereinafter represented by r) is the linear velocity (v1 [m / s]) of the molten polyester when discharged from a die hole, represented by the following formula: ) To the linear velocity (v2 [m / s]) of the strand immediately before being cut.

r = (v2 [m / s]) / (v1 [m / s])
here,
v1 [m / s] = (discharge weight per unit time (s: second) per hole (s: second) / polyester density [kg / m ³ ]) / (die hole outlet area [m ² ])
It is.
v2 [m / s] is the linear velocity of the strand immediately before being cut by the cutter, and is usually the same as the linear velocity of the strand when it is cut by the cutter. ), The number of rotations (R [1 / s]) and the length in the discharge direction of the particles after cutting (L [m]).
v2 [m / s] = RnL [m / s]

Moreover, when the take-up roll is installed in order to take up the strand before the cutter, it can be calculated according to the following formula from the rotation speed of the take-up roll as a tangential component of the rotational speed of the take-up roll side surface. .
v2 [m / s] = (take-off roll diameter [m]) × (revolution speed of take-up roll [1 / s]) × (circumference ratio)
In particular, a device in which a take-up roll is installed in order to stably guide the strand to the cutter is preferably used before the cutter, and in that case, a method of obtaining v2 [m / s] from the number of rotations of the take-up roll. Is convenient and preferably used.

  The take-off speed ratio r is adjusted so that the strand is guided to the cutter together with the cooling liquid fluid and appropriately cut. The adjusting method can be performed, for example, by changing the flow rate of the liquid fluid that moves together with the strands and / or by changing the rotational speed of the take-up roll that takes up the strands just before being cut by the cutter.

  The lower limit value of the take-off speed ratio r is 1.5, preferably 2. If it is less than 1.5, the strand discharged from the die hole will not stably move with the liquid fluid, and the strand will meander or become too thick and subsequent cutting with a cutter will not be smooth. The diameter may not be uniform, and irregular shaped particles having a particularly large particle size may be generated. The upper limit of the take-up speed ratio r is 100, preferably 50, more preferably 20. If it exceeds 100, the strand may be too thin and difficult to cut with a cutter, or the strand may break easily before being guided to the cutter.

  In the granulating method of the present invention, the melted polyester is discharged into a strand shape by introducing the melted polyester to a die head through an extruder, a gear pump, or a pipe connected to a pressurized melt polycondensation reaction tank. Further, it can be discharged in a strand form from one or a plurality of die holes provided at the tip of the die head. The hole shape of the die hole can be, for example, a circle, an ellipse, a polygon, a star, or some of these shapes (semi-circle, semi-ellipse, etc.), or a combination of these (a semi-circle at each end of the rectangle) Etc.). The size of the hole of the die hole is preferably 0.7 to 5.0 mm in terms of the diameter of a circle having an area equal to the area of the hole of the die hole. When the thickness is less than 0.7 mm, the discharge pressure becomes too high, and the discharge becomes difficult and the strands are easily broken. On the other hand, if it exceeds 5.0 mm, it is difficult to optimize the take-up speed ratio r and it is difficult to obtain small-diameter particles.

  Further, when the molten polyester is discharged in a strand form from the die hole, the linear velocity (v1 [m / s]) of the molten polyester discharged from the die hole is preferably 0.1 to 3 m / s. If the linear velocity of the polyester discharged from the die hole is less than 0.1 m / s, the take-up speed ratio r tends to be too large and the strands tend to be too thin, and proper cutting with a cutter tends to be difficult. If the linear velocity exceeds 3 m / s, the take-up velocity ratio r is small and the strands are thick, and it tends to be difficult to obtain particles having a small particle size.

Moreover, it is preferable that the discharge direction of the molten polyester when discharging the molten polyester in a strand form from the die hole is within an angle formed between the horizontal direction and a direction inclined 70 ° downward from the horizontal direction. When the discharge direction is within this angular range, the strand bending angle is small at the contact point at which the discharged strand polyester contacts the liquid fluid, and therefore, the strand vibration is small and particles can be obtained stably. Here, the discharge direction of the molten polyester is the inclination of the tangent line in the vicinity of the die plate of the arc drawn by the strand.
A preferable discharge direction is an angle range inclined by 60 ° downward from the horizontal direction and the horizontal direction, and more preferably an angle range inclined by 50 ° downward from the horizontal direction and the horizontal direction.

  In the step (2) of the granulating method of the present invention, the strand polyester discharged from the die hole is brought into contact with a cooling fluid fluid, and the strand polyester is guided to the cutter together with the fluid fluid. The liquid fluid is not particularly limited as long as it has the ability to cool the strand discharged in a molten state and can move with the strand. As the liquid fluid, use of water is safe in terms of handling, it is easy to obtain a liquid with few foreign matters, and it is inexpensive and suitable. The linear velocity of the liquid fluid is preferably about 0.5 to 10 times the linear velocity v2 of the strand immediately before cutting, more preferably 1 to 2 times.

  The temperature of the liquid fluid to be used, for example, water is appropriately selected according to the temperature at the time of melting of the polyester, the melting point, the softening point, the glass transition point, the strand discharge angle, the thickness, etc. Is selected from 25 ° C. or higher and 95 ° C. or lower, preferably 90 ° C. or lower. If the temperature is lower than 5 ° C, the strands may be cooled too rapidly, and vibration due to shrinkage strain may occur, or vacuum voids may be formed in the strands. If the temperature exceeds 95 ° C, the cooling becomes insufficient and the strands are fused. Or the particles after cutting may be fused with each other. In particular, when the polyester is polyethylene terephthalate, the lower limit of the water temperature is preferably 10 ° C., more preferably 40 ° C., and the upper limit is preferably 70 ° C., more preferably 65 ° C.

  In the granulation method of the present invention, the strand-like polyester discharged from the die hole comes into contact with the liquid fluid. At the time of contact, the die-hole discharge port and the contact point between the strand-like polyester and the liquid fluid (when water is used as the liquid fluid) Is also preferably 10 to 500 mm. When the linear distance is within this range, the arrangement and adjustment of the equipment are easy, and there are few problems of strand vibration and strand breakage, and the polyester can be stably formed into a strand shape, thereby stably. Particles can be obtained.

  In particular, in order to obtain particles having a preferable shape and particle size described later, the lower limit of the linear distance between the discharge port of the die hole and the contact point between the strand-like polyester and the liquid fluid is 100 mm, more preferably 130 mm, especially Preferably, the upper limit is 150 mm and the upper limit is 500 mm. When the linear distance is within this range, it becomes possible to sufficiently stretch the strand before the strand-shaped molten polyester contacts the liquid fluid, and more stably fine polyester particles having an average particle diameter of 2 mm or less. Since it can obtain, it is especially preferable.

The moving speed of the liquid fluid guided to the cutter together with the strand-like polyester is determined by the linear velocity of the strand.
The length of the cooling part (for example, the water cooling part) of the strand by the liquid fluid varies depending on the temperature of the discharged strand polyester, the size of the strand, etc., but is usually 0.5 to 10 m. The cooling section has an inclination of 5 ° to 80 °, preferably 8 ° to 60 °, and more preferably 10 ° to 45 ° in order to smoothly guide the strand and liquid fluid to the cutter. Therefore, it is preferable because particles can be obtained stably.

  In the step (3) in the granulation method of the present invention, the strand-like polyester led to the cutter is cut, but the strand-like polyester only needs to be cooled to a level that can be cut by the liquid fluid.

  The polyester used for producing small particles by the granulation method of the present invention is not particularly limited as long as the melt viscosity at the time of discharge is 0.5 Pa · s to 50 Pa · s, but dicarboxylic acid and / or ester thereof. A melted polyester obtained by performing an esterification reaction and / or a transesterification reaction between a formable derivative and a diol and further performing a melt polycondensation reaction is preferably used as it is.

  The intrinsic viscosity of the polyester to be granulated according to the present invention is equivalent to the intrinsic viscosity of the strand-like polyester discharged from the die hole in a molten state, and is preferably 0.20 to 0.40 dL / g. The lower limit is more preferably 0.25 dL / g, and the upper limit is more preferably 0.35 dL / g, and particularly preferably 0.32 dl / g. A polyester having a polymerization degree such that the intrinsic viscosity is less than the lower limit tends to make it difficult to obtain a stable strand because the melt viscosity is too low when discharged from a die hole. Exceeding the upper limit makes it difficult to pass through a small-diameter die hole necessary to obtain small-diameter polyester particles, and requires expensive equipment for high-viscosity liquid stirring and high-vacuum reaction in the melt polycondensation reaction process described above. This is not preferable.

  The polyester used in the granulation method of the present invention is a melt polycondensation reaction using a polycondensation catalyst through an esterification reaction and / or a transesterification reaction between a dicarboxylic acid and / or an ester-forming derivative thereof and a diol. However, the method is not particularly limited, and basically known polyester production methods can be employed. For example, a dicarboxylic acid component such as terephthalic acid and a diol component such as ethylene glycol and butylene glycol are charged into a slurry preparation tank and stirred and mixed to form a raw material slurry, which is heated at normal to pressurized pressure in an esterification reaction tank After the esterification reaction while distilling off water generated by the reaction, the polyester low molecular weight product (oligomer) as the obtained esterification reaction product is transferred to a polycondensation reaction tank and heated under reduced pressure. And a method of obtaining a polyester by melt polycondensation reaction using a polycondensation catalyst.

If the dicarboxylic acid component is an ester-forming derivative of a dicarboxylic acid, such as dimethyl terephthalate, having a melting point close to the polycondensation reaction temperature, it is melted without slurry with the diol and then transesterified with the diol. Can also be provided.
As a method of performing the above reactions, any of a continuous method, a batch method, and a semi-batch method may be used, and these methods may be combined. Moreover, the esterification reaction tank (or transesterification reaction tank) and the melt polycondensation reaction tank may each be one stage or multistage.

  The polyester particles obtained by the granulation method of the present invention are suitably used in a process of crystallization after granulation and further solid phase polycondensation. Therefore, the granulation method of the present invention is suitably applied to a step of producing a polyester resin, for example, a polyethylene terephthalate resin and / or a polybutylene terephthalate resin by performing such solid phase polycondensation. That is, it is a process for producing a polyester resin in which the main component of dicarboxylic acid as a polyester raw material is terephthalic acid and / or dimethyl terephthalate, and the main component of diol is ethylene glycol and / or 1,4-butanediol. Here, “main component” means that terephthalic acid accounts for 85 mol% or more of the total dicarboxylic acid component, and ethylene glycol or 1,4 butanediol accounts for 85 mol% or more of the total diol component.

  In the method for producing polyester used in the present invention, a polycondensation catalyst is usually used for the melt polycondensation reaction. The polycondensation catalyst to be used is not particularly limited, and a conventionally known catalyst can be usually used as a polycondensation catalyst for producing a polyester resin. For example, a germanium compound, an antimony compound, a titanium compound, a manganese compound, a zinc compound, an aluminum compound, a tungsten compound, and the like are used. Among these, one or more metal compounds selected from a germanium compound, an antimony compound, and a titanium compound are used. Is preferred.

  As the molten polyester in the granulation method of the present invention, the polyester obtained by the above melt polycondensation reaction is solidified and then remelted before being used as a raw material in the particle production method of the present invention. Even if it uses, the thing of the molten state obtained by the melt polycondensation reaction may be used as it is. The method of solidifying the polyester obtained by the melt polycondensation reaction is not so preferable because the operation required to make pellets at that stage and the energy required for remelting are required, and the melted polycondensation reaction is not preferred. It is preferable to obtain a polyester and use the polyester as it is as a raw material for the granulation method of the present invention.

  The polyester obtained by the melt polycondensation reaction is preferably supplied to a die head connected to the melt polycondensation reaction tank via a pipe and discharged from a plurality of die holes provided at the tip of the die. The discharged strand-like polyester is granulated by the method of the present invention. Note that a gear pump or a filter may be provided in the pipe between the melt polycondensation reaction tank and the die head as required.

The polyester particles obtained by the granulation method of the present invention preferably have an average particle size of 0.5 mm or more, more preferably 0.6 mm or more, particularly preferably 0.65 mm or more, and 2.0 mm or less. Preferably, it is 1.8 mm or less, more preferably 1.6 mm or less. Particles that are made into particles by the production method of the present invention and have an average particle diameter in this range are more preferable because the solid phase polycondensation rate when the polyester particles are subjected to solid phase polycondensation is high. When the size of the particles is in the range of the lower limit or more, trouble is unlikely to occur during the subsequent process or pneumatic transportation, which is more preferable. Moreover, when it is in the range of the upper limit or less, it is more preferable because troubles of crushing and fine powder generation at the time of granulation hardly occur and a solid phase polycondensation reaction time required to reach a desired molecular weight can be shortened.
Here, the average particle diameter of the particles is determined by preparing an integrated distribution curve by the dry screening test method described in JIS K0069, and taking the value when the integrated percentage is 50% as the average particle diameter.

  The polyester particles obtained by the granulation method of the present invention preferably have a substantially elliptic cylinder shape. The “substantially elliptic cylinder shape” represents a shape including an elliptic cylinder, a rectangular parallelepiped, and an intermediate shape thereof. Here, the “elliptical column” is a column having a cut surface having an elliptical shape, and the “cuboid” is a column having a cut surface having a rectangle. The “intermediate shape” means that the cut surface is inscribed in a rectangle having a long side and a short side equal to the major axis and minor axis of the cut surface, for example, at least a part of the four corners of the rectangle is an arc shape. In this application, it is expressed as `` an elliptic cylinder that is almost a rectangular parallelepiped '' or `` an elliptic cylinder that is close to a shape with semi-cylinders attached to both ends of the rectangular parallelepiped ''. To do. The polyester particles of the present invention are preferable in that the specific surface area (surface area / volume) of the particles is increased and the solid phase polycondensation rate is relatively increased by having the shape as described above.

  Preferred polyester particles obtained by the granulation method of the present invention have a length of 0.5 mm or more, 2.5 mm or less, more preferably 2 mm or less, and particularly preferably 1.5 mm or less. The major axis of the cut surface is 0.5 mm or more, 2.5 mm or less, more preferably 2 mm or less, particularly preferably 1.5 mm or less, and the minor axis of the cut surface is 0.3 mm or more, 2 mm or less. More preferably, it is 1.5 mm or less, and particularly preferably 1.2 mm or less.

Preferred polyester particles have an intrinsic viscosity of 0.20 to 0.40 dL / g, a length of 0.5 to 2.5 mm, and a major axis and a minor axis of the cut surface of 0.5 to 2.5 mm, 0, respectively. 3 to 2 mm, and has a substantially elliptical cylindrical shape.
Particularly preferred sizes and shapes of the polyester particles are 0.5 to 1.5 mm in length, 0.5 to 1.5 mm and 0.3 to 1.2 mm in the major axis and minor axis of the cut surface, respectively. It has a substantially elliptical cylindrical shape. In the case of such a shape, since the specific surface area of the particles is increased, the solid phase polycondensation rate is relatively increased as compared with the cylindrical particles as described in Patent Document 6, which is advantageous in the production of the polyester resin. is there.

  The polyester particles obtained by the granulation method of the present invention are preferably further subjected to solid phase polycondensation. In particular, when polyester resin particles having crystallinity are desired, the polyester particles are subjected to a solid phase polycondensation step. Thus, polyester resin particles having a higher degree of polymerization can be produced. The polyester resin particles thus produced are polyester resin particles having more preferable physical properties in terms of molding processability, mechanical properties of the obtained molded product, and the like.

  The polyester particles of the present invention, for example, the polyester particles obtained by the above granulation method, are subjected to a solid phase polycondensation step to produce polyester resin particles, but the specific method of the solid phase polycondensation is not particularly limited. Various methods can be performed as necessary. As a known method, for example, after performing crystallization and drying treatment by fluidizing polyester particles in an inert gas stream at 120 to 180 ° C. for 0.5 to 12 hours, it is usually 180 ° C. or more and polyester. And a method of continuously carrying out in a moving bed under an inert gas flow at a temperature not higher than 5 ° C. below the melting point. The solid phase polycondensation time may be set according to the intrinsic viscosity of the target polyester resin, and is usually about 1 to 50 hours. The intrinsic viscosity after solid phase polycondensation is usually 0.70 dL / g, preferably 0.72 dL / g, more preferably 0.74 dL / g, and the upper limit is usually 1.50 dL / g, preferably 1 .45 dL / g, more preferably 1.40 dL / g. When the intrinsic viscosity of the polyester resin particles obtained by the production method of the present invention is within this range, the polyester resin particles are more preferable because the molded article formed by molding the polyester resin particles is excellent in mechanical strength and melt moldability.

  In particular, in the production of a polyester resin by solid phase polycondensation according to the present invention, it is preferable to solid-phase polycondensate polyester particles having a particularly preferable size and shape obtained by the granulation method of the present invention as described above. In this case, slight shrinkage due to crystallization occurs, but the polyester resin after solid phase polycondensation has an intrinsic viscosity of 0.70 dL / g or more, a length of 0.5 mm to 1.5 mm, and a cut surface. It is the most preferable granular polyester resin having a substantially elliptical column shape having a major axis and a minor axis of 0.5 mm to 1.5 mm and 0.3 mm to 1.2 mm, respectively. The polyester resin having such a size and shape of the present invention can be subjected to solid-phase polycondensation in a short time when it is produced, and the melting time when the polyester resin of the present invention is thermoformed. It is more preferable because it can be short.

The polyester resin particles produced by the solid phase polycondensation method of the present invention are excellent in mechanical strength and melt moldability, and after forming a preform by injection molding or extrusion molding, filling of beverages by stretch blow molding, etc. It can be suitably used as a bottle used in the above. It can also be made into a bottle by direct blow molding.
Further, the polyester resin particles can be suitably used for various applications such as packaging materials by forming into a film or sheet by extrusion molding or stretch molding, and can also be suitably used as a fiber by extrusion / stretch molding.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
In addition, the physical-property evaluation method in this invention is as follows.

<Intrinsic viscosity>
About 0.25 g of the sample (polymer) is added to about 25 mL of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio 1/1), and the concentration becomes 1.00 × 10 ⁻² kg / L. After being dissolved at 140 ° C., the sample solution was cooled to 30 ° C., and a sample solution having a concentration of 1.00 × 10 ⁻² kg / L with a fully automatic solution viscometer (“2CH type DJ504” manufactured by Sentec). And the falling seconds of only the solvent were measured and calculated by the following formula.

[η] = [(1 + 4K _H η _SP ) ^0.5 −1] / (200K _H C)
Here, η _sp = η / η ₀ −1, η is the sample solution drop seconds, η ₀ is the solvent drop seconds, C is the polymer solution concentration (kg / L), and K _H is the Huggins constant. It is. K _H adopted the 0.33.

<Melt viscosity>
After the sample was vacuum-dried at 120 ° C. for 14 hours, a test piece having a diameter of 25 mm and a thickness of 2 mm was produced at a temperature of 280 ° C. using a press molding machine (“Mini Press” manufactured by Toyo Seiki Seisakusho). The sample was stored in a desiccator until immediately before the measurement.
As a measuring device, a dynamic viscoelasticity measuring device (“ARES100 type” manufactured by TA Instruments Co., Ltd.) was used, and a detector was a full scale type of 10 g. A parallel plate having a diameter of 25 mm was used as a measurement jig, and the plate interval was 1.5 mm. The measurement procedure is as follows.

After heating the heating oven to the measurement temperature, the sample is inserted between the parallel plates, the heating oven is closed, the sample is confirmed to have melted, the upper plate is lowered and brought into close contact with the sample, and the plate interval is 1 Compressed to .55 mm.
Next, the heating oven was opened to remove the sample protruding from the plate, the heating oven was closed again, the plate interval was set to 1.50 mm, and it was confirmed that the measurement temperature was stable, and measurement was started. The strain during measurement was 30%. The time from sample insertion to the start of measurement was 8 minutes.
In this way, the complex viscosity at the temperature of the molten polyester when discharged from the die hole at a shear rate of 10 rad / s was measured, and this was taken as the melt viscosity.

<Average particle size>
It was measured by a dry sieving test method described in JIS K0069.

Polyesters used for the production of the polyester particles described in Examples 1 to 6 and Comparative Example 1 were produced as follows.
<Polyester production>
A slurry preparation tank having an agitator, an ethylene glycol charging pipe and a terephthalic acid charging pipe; a pipe for transferring the slurry to the first esterification tank; an agitator, a separation tower, a raw material receiving port, a catalyst charging pipe and a reactant transfer pipe Complete mixing type first and second esterification reaction tanks; piping for transferring the esterification reaction product (oligomer) to the melt polycondensation reaction tank; complete mixing type having a stirrer, separation tower, oligomer receiving port and catalyst charging pipe First melt polycondensation reaction tank; plug flow type second and third melt polycondensation reaction tanks having stirrer, separation tower, polymer receiving port; strand cutting using a continuous polyester production apparatus equipped with a polyester extraction pipe A polyester having a low polymerization degree was prepared. Specifically, it is as follows.

[Polyester A: Raw material A]
In a slurry preparation tank, a terephthalic acid / ethylene glycol (molar ratio 1: 1.5) slurry to which normal phosphoric acid was added so that the concentration of phosphorus in the obtained polyester was 22 ppm by weight as phosphorus atoms was prepared. Also, 400 parts by weight of bis- (betahydroxyethyl) terephthalate was charged into the first esterification tank and melted in a nitrogen atmosphere, and the temperature was 262 ° C. and the pressure was 96 kPaG (hereinafter, G represents relative pressure to atmospheric pressure). The slurry prepared in the slurry preparation tank is continuously charged at 135 parts by weight / hour and the average residence time as polyester is 4.5 hours, and generated from the separation tower. While performing the esterification reaction while distilling off water, the reaction solution was continuously transferred to the esterification second reaction tank.

In the second esterification reactor, an antimony trioxide ethylene glycol solution (with a temperature of 260 ° C., a pressure of 5 kPaG, a residence time of 1.5 hours, and an antimony trioxide concentration of 183 ppm by weight as antimony atoms) Concentration: 1.8% by weight as the concentration of antimony atoms) was continuously added to carry out the esterification reaction, and the mixture was continuously transferred to a fully mixed first melt polycondensation reaction tank through a transfer pipe. In the first melt polycondensation reaction tank, the reaction was carried out at a pressure of 2.5 kPaA (hereinafter, A indicates an absolute pressure), a temperature of 273 ° C., and a residence time of 1.0 hour in the polycondensation reaction tank. The polyester was taken out and cooled and solidified through an extraction pipe in the middle of a transfer pipe to the second melt polycondensation reaction tank.
The intrinsic viscosity of the obtained polyester was 0.215 dL / g.

  This cooled and solidified polyester is compressed and crushed by passing it between two stainless steel rolls that have parallel rotation axes and are arranged in close proximity, with irregularities on the surface and rotating in different directions, four times. Amorphous polyester particles having a particle size ranging from 0.1 mm to 3.36 mm were obtained. This amorphous polyester particle is referred to as “raw material A”.

[Polyester B: Raw material B]
The reaction up to the first melt polycondensation reaction tank was performed in the same manner as in the production method of the raw material A, and the obtained polyester was transferred to the second melt polycondensation reaction tank. In the second melt polycondensation reaction tank, a melt polycondensation reaction was performed at a pressure of 2.0 kPaA, a temperature of 280 ° C. and a residence time of 1.0 hour, and the obtained polyester was transferred to the third melt polycondensation reaction tank through a transfer pipe. . In the third melt polycondensation reaction tank, the melt polycondensation reaction was performed at a pressure of 1.5 kPaA, a temperature of 280 ° C., and a residence time of 1.2 hours. The obtained polyester was extracted and led to a die head through piping, taken out in a strand form from the die hole, solidified with water, and then cut with a cutter to obtain polyester particles having an intrinsic viscosity of 0.403 dL / g and an average particle size of 3 mm. . This polyester particle is referred to as “raw material B”.

<Particle formation of polyester>
The raw material A and the raw material B obtained by the above method are put into an inert oven in which nitrogen is circulating, dried at a temperature of 180 ° C. for 3 hours, mixed at a predetermined ratio shown in Table 1, and 45 mmφ biaxial extrusion The product was supplied to a machine and discharged in a strand form from a die plate at a resin temperature of 280 ° C. This strand-shaped polyester was made into particles by a strand cut method using a pelletizer (P-USG200) manufactured by Reuters Automatic. In other words, strand polyester is transported to the cutter together with water while being contacted and cooled with water at a predetermined temperature. At that time, it is picked up by a pair of take-up rolls installed in front of the cutter, supplied to the cutter, and fixed. Polyester particles were obtained by cutting with a cutter having teeth and rotating teeth. At that time, the water-cooled length was 2 m, the slope of the water-cooled portion was an angle of 20 ° with respect to the horizontal plane, and the number of rotating teeth was 60.
The operating conditions such as the strand discharge linear velocity and the take-off velocity ratio in each example are collectively shown in Table 1.

Example 1
The raw material A was continuously supplied to an extruder at 48 kg / hour and melted, and discharged at a resin temperature of 280 ° C. in a strand form from a die plate having six 2 mmφ circular die holes. The discharge direction was an angle of 45 ° downward from the horizontal direction. The discharge linear velocity of the polyester calculated with the density of the polyester at a resin temperature of 280 ° C. as 1.23 kg / L is 0.58 m / sec.

  The strand-shaped polyester is used in a state where the linear distance (hereinafter referred to as “air-cooling distance”) between the discharge port of the die hole and the contact point (water landing point) of the strand-shaped polyester with water becomes 140 mm. It was made to land on the cooling zone, conveyed while being cooled with water at 50 ° C., taken up by a take-up roll, and supplied to the cutter. The strand take-up speed was 2.33 m / sec, and the take-up speed ratio was 4.0. The cutter was granulated by adjusting the ratio of the number of rotations of the take-up roll and the rotating teeth so that the length in the take-up direction of the particles was 1.5 mm.

  As a result, elliptical columnar polyester particles having a length of 1.5 mm and a substantially rectangular parallelepiped shape having a major axis and a minor axis of 1.5 mm and 0.7 mm, respectively, were obtained. The average particle size of these particles was 1.5 mm. The amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 3% by weight. Further, the melt viscosity of the particles at 280 ° C. was 1.7 Pa · s, and the intrinsic viscosity was 0.205 dL / g. The operating conditions and results are shown in Table 1.

(Example 2)
The polyester was granulated in the same manner as in Example 1 except that the operating conditions were changed as shown in Table 1. As a result, elliptical columnar polyester particles having a length of 1.5 mm and a substantially rectangular parallelepiped shape having a major axis and a minor axis of 1.5 mm and 0.8 mm, respectively, were obtained. The average particle size of these particles was 1.5 mm. The amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 3% by weight. The operating conditions and results are shown in Table 1.

(Example 3)
The polyester was granulated in the same manner as in Example 1 except that the operating conditions were changed as shown in Table 1. As a result, elliptical columnar polyester particles having a length of 1.5 mm and a long and short diameter of the cut surface of 1.4 mm and 0.7 mm, respectively, which are almost a rectangular parallelepiped were obtained. The average particle size of these particles was 1.5 mm. The amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 2% by weight. The operating conditions and results are shown in Table 1.

Example 4
The polyester was granulated in the same manner as in Example 1 except that the operating conditions were changed as shown in Table 1. As a result, elliptical columnar polyester particles having a length of 1.5 mm and a long and short diameter of the cut surface of 1.4 mm and 0.9 mm, respectively, which are almost rectangular parallelepiped were obtained. The average particle size of these particles was 1.5 mm. The amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 2% by weight. The operating conditions and results are shown in Table 1.

(Example 5)
In Example 1, the die plate is changed to a die plate having two circular die holes of 3 mmφ, the cooling water temperature is 61 ° C., the number of rotations of the rotating teeth of the cutter is adjusted, and the length in the particle take-up direction is 1 Particleization was performed in the same manner as in Example 1 except that the operation conditions were changed as shown in Table 1 and the operation conditions were changed as shown in Table 1. As a result, an elliptical columnar polyester particle having a length of 1.25 mm and a substantially rectangular parallelepiped having a major axis and a minor axis of the cut surface of 1.2 mm and 0.8 mm, respectively, was obtained. The average particle size of these particles was 1.2 mm. The generated amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 1% by weight. The operating conditions and results are shown in Table 1.

(Comparative Example 1)
Polyester particles were tried in the same manner as in Example 1 except that the operating conditions were changed as shown in Table 1. As a result, the strands meandered, a large number of irregularly shaped particles and uncut strands were generated, and stable granulation could not be performed. The operating conditions and results are shown in Table 1.

(Example 6)
The polyester particles obtained in Example 5 are put into an inert oven in which nitrogen is circulated, crystallized at a temperature of 180 ° C. for 2 hours, and subsequently subjected to solid phase polycondensation at 230 ° C. for 12 hours to obtain a high molecular weight polyester. Particles were obtained. The particles had an elliptical columnar shape with a length of 1.2 mm, a major axis and a minor axis of the cut surface of 1.2 mm and 0.8 mm, respectively, and an intrinsic viscosity of 0.845 dL / g.

(Example 7)
Using the polyester continuous production apparatus used in <Polyester Production>, an esterification reaction between a dicarboxylic acid and a diol is performed, and a melted polycondensation reaction is performed to obtain a melted polyester, and the resulting melted state This polyester was used as it was in the production of the particles to produce polyester particles having a low polymerization degree. Specifically, it is as follows.

  In a slurry preparation tank, a terephthalic acid / ethylene glycol (molar ratio 1: 1.5) slurry containing tetra-n-butyl titanate in an amount of 8 ppm by weight as titanium with respect to the obtained polyester was prepared. In addition, 400 parts by weight of bis- (betahydroxyethyl) terephthalate was charged in the first esterification tank and melted in a nitrogen atmosphere, and was maintained in a temperature of 262 ° C. and a pressure of 96 kPaG. The slurry was continuously charged at 135 parts by weight / hour and the average residence time as polyester was 4.5 hours, and the reaction liquid was added while conducting esterification while distilling off the water produced from the separation tower. It was continuously transferred to the esterification second reaction tank.

In the second esterification reactor, the esterification reaction is carried out at a temperature of 260 ° C. and a pressure of 5 kPaG with a residence time of 1.5 hours, and the reaction product is continuously transferred to the fully mixed first melt polycondensation reactor through a transfer pipe. did.
In the first melt polycondensation reaction tank, the reaction was performed at a temperature of 270 ° C. and a pressure of 4.0 kPaA at a residence time of 1.0 hour, and the reaction product was continuously transferred to the second melt polycondensation reaction tank through a transfer pipe. . In the second melt polycondensation reaction tank, a melt polycondensation reaction was performed at a temperature of 270 ° C. and a pressure of 4.0 kPaA at a residence time of 1.0 hour, and the reaction product was transferred to the third melt polycondensation reaction tank through a transfer pipe. . In the third melt polycondensation reaction tank, the melt polycondensation reaction was carried out at a temperature of 270 ° C. and a pressure of 4.0 kPaA with a residence time of 1.2 hours.

  The molten polyester thus obtained was directly led to a die head through a gear pump and an extraction pipe, taken out in a strand form from the die hole, cooled with water, and then granulated with a pelletizer (P-USG100) manufactured by Reuter Automatic. The particle forming method is a strand cutting method. Specifically, the strand-shaped polyester is transported in the cutter direction with water while being cooled by contacting with water, and sandwiched between a pair of take-up rolls installed in front of the cutter. The polyester particles were obtained by picking up and supplying to the cutter and cutting with a cutter having fixed teeth and rotating teeth. At that time, the water-cooled length was 2 m, the slope of the water-cooled part was an angle of 20 ° with respect to the horizontal plane, and the number of rotating teeth was 60.

Here, the discharge amount of the molten polyester is 126 kg / hour, the temperature is 270 ° C., and it is discharged in the form of a strand from a die plate having 4 circular die holes of 3 mmφ with an angle of 45 ° downward from the horizontal direction. It was. The polyester discharge linear velocity calculated by setting the density of the polyester at a resin temperature of 270 ° C. to 1.23 kg / L is 1.01 m / sec.
This strand-like polyester was landed in the cooling zone (water cooling part) of the strand cutter in a state where the air cooling distance was 170 mm, conveyed while being cooled with water at 50 ° C., taken up by a take-up roll, and supplied to the cutter. The strand take-up speed was 3.00 m / sec, and the take-up speed ratio was 3.0. The cutter was made into particles by adjusting the ratio of the number of rotations of the take-up roll and the rotating teeth so that the length in the take-up direction of the particles was 1.0 mm.

  As a result, elliptical columnar polyester particles having a length of 1.0 mm and a major axis and a minor axis of the cut surface of 1.9 mm and 1.3 mm, respectively, having a shape similar to a shape in which half cylinders are attached to both ends were obtained. The average particle size of the particles was 1.8 mm. The amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 0.02% by weight. Further, the melt viscosity of the particles at 270 ° C. was 9.1 Pa · s, and the intrinsic viscosity was 0.290 dL / g. The operating conditions and results are shown in Table 2.

(Example 8)
Polyester was granulated in the same manner as in Example 7 except that the operating conditions were changed as shown in Table 2 by changing the discharge amount of molten polyester at 98 kg / hour. As a result, elliptical columnar polyester particles having a length of 1.0 mm and a major axis and a minor axis of the cut surface of 1.6 mm and 1.2 mm, respectively, having a shape similar to a shape in which half cylinders are attached to both ends, were obtained. The average particle size of these particles was 1.5 mm. The generation amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm generated in this granulating step was 0.01% by weight. The operating conditions and results are shown in Table 2.

Example 9
Polyester was granulated in the same manner as in Example 7 except that the operating conditions were changed as shown in Table 2 by changing the discharge amount of the molten polyester at 61 kg / hour. As a result, elliptical columnar polyester particles having a length of 1.0 mm and a major axis and a minor axis of the cut surface of 1.3 mm and 0.9 mm, respectively, having a shape similar to a shape in which half cylinders are attached to both ends, were obtained. The average particle size of these particles was 1.3 mm. The generation amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm generated in this granulating step was 0.01% by weight. The operating conditions and results are shown in Table 2.

(Example 10)
Polyester was granulated in the same manner as in Example 7 except that the operating conditions were changed as shown in Table 2. As a result, elliptical columnar polyester particles having a length of 1.0 mm and a major axis and a minor axis of the cut surface of 2.5 mm and 1.8 mm, respectively, having a shape similar to a shape in which half cylinders are attached to both ends were obtained. The average particle size of these particles was 2.2 mm. The generation amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 0.03% by weight. The operating conditions and results are shown in Table 2.

(Comparative Example 2)
Polyester particles were tried in the same manner as in Example 7 except that the operating conditions were changed as shown in Table 2. As a result, since the strands meandered, together with elliptical columnar polyester particles having a length of 1.0 mm and a major axis and a minor axis of the cut surface of 3.1 mm and 1.9 mm, respectively, and a shape close to a shape with semi-cylinders attached to both ends of a rectangular parallelepiped Obliquely cut products and irregularly shaped particles having a length of 10 mm or more were obtained. The amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm was 4% by weight. The operating conditions and results are shown in Table 2.

(Comparative Example 3)
Change the discharge direction of the molten polyester from the horizontal direction to 90 ° angle (vertically downward), change the air cooling distance of the strand polyester to 58mm, change the cooling water temperature to 20 ° C, and take up the strand speed Was changed to 1.00 m / sec, the take-up speed ratio was changed to 1.0, the length in the take-up direction of the particles was changed to 3.0 mm, and the operating conditions were changed as shown in Table 2. Other than that, polyester particles were tried in the same manner as in Example 7. As a result, since the strands meandered, along with columnar polyester particles having a length of 3.0 mm and a diameter of the cut surface of 3.0 mm, crushed products of particles, oblique cut products, and deformed particles having a length of 10 mm or more Obtained. The amount of these irregularly shaped particles generated was 10% by weight. Moreover, most of the obtained particles had bubbles inside because the cooling water temperature was low and the strands were thick. The operating conditions and results are shown in Table 2.

(Example 11)
By changing the temperature of the second and third melt polycondensation reaction tanks to 275 ° C., the temperature of the molten polyester at the time of discharge is changed to 275 ° C., the die plate is changed to one with 10 hole holes, and the molten polyester The polyester was granulated in the same manner as in Example 7 except that the discharge amount was changed to 78 kg / hour and the operating conditions were changed as shown in Table 2. As a result, elliptical columnar polyester particles having a length of 1.0 mm and a major axis and a minor axis of the cut surface of 1.0 mm and 0.7 mm, respectively, having a shape similar to a shape in which semi-columns are attached to both ends, were obtained. The average particle size of these particles was 1.0 mm. The generation amount of irregularly shaped particles that did not pass through a sieve having an aperture of 2.8 mm, generated in this granulating step, was 0.03% by weight. The operating conditions and results are shown in Table 2.

(Example 12)
The polyester particles obtained in Example 9 are put into an inert oven in which nitrogen is circulating, crystallized at a temperature of 180 ° C. for 2 hours, and subsequently subjected to solid phase polycondensation at 230 ° C. for 12 hours to obtain a high molecular weight polyester. Particles were obtained. This particle has an elliptical columnar shape close to a shape in which semi-cylinders are attached to both ends of a substantially rectangular parallelepiped having a length of 0.9 mm and a major axis and a minor axis of the cut surface of 1.3 mm and 0.9 mm, respectively, and the intrinsic viscosity is 0. 866 dL / g.

(Comparative Example 4)
Among the polyester particles obtained in Comparative Example 3, particles having a relatively good shape were selected, put into an inert oven in which nitrogen was circulated, and crystallized at a temperature of 180 ° C. for 2 hours. As a result, most of the particles were ruptured by the influence of the internal bubbles and became irregular shaped particles. The particles obtained in Comparative Example 3 were not suitable for solid phase polycondensation.

Claims (12)

A process for producing polyester particles, wherein the following steps (1) to (3) are sequentially performed, and the take-off speed ratio represented by the following formula of the strand-like polyester is 1.5 to 100.
(1) A step of discharging a molten polyester having a melt viscosity of 0.5 Pa · s to 50 Pa · s into a strand from a die hole having a hole diameter converted to a diameter of a circle having an area equal to the die hole area of 0.7 to 3 mm (2 ) A step of bringing the obtained strand-shaped polyester into contact with a cooling liquid fluid and guiding it to the cutter together with the liquid fluid (3) A step of cutting the strand-shaped polyester guided to the cutter
      The method for producing polyester particles according to claim 1, wherein the liquid fluid is water having a temperature of 5 to 95 ° C. The polyester particles according to claim 1 or 2 , wherein the molten polyester has a linear velocity (v1 [m / s]) of 0.1 to 3 m / sec when discharging the molten polyester in a strand form from a die hole. Manufacturing method. Discharge direction of the molten polyester when discharging the molten polyester from the die holes in a strand shape, claims 1 to 3, characterized in that in the angle formed by the horizontal and 70 ° tilted direction from the horizontal direction downwardly The manufacturing method of the polyester particle of any one of these. When the strand-like polyester discharged from the die hole is brought into contact with the liquid fluid, the linear distance between the discharge hole of the die hole and the contact point between the strand-like polyester and the liquid fluid is 10 to 500 mm. Item 4. The method for producing polyester particles according to any one of Items 1 to 3 . The average particle diameter of a polyester particle is 0.6-2.0 mm, The manufacturing method of the polyester particle of any one of the Claims 1 thru | or 5 characterized by the above-mentioned.
The method for producing polyester particles according to any one of claims 1 to 6 , wherein the shape of the polyester particles is substantially an elliptic cylinder shape. The polyester particles are substantially elliptical cylinders having a length of 0.5 mm to 2.5 mm and a major axis and a minor axis of the cut surface of 0.5 mm to 2.5 mm and 0.3 mm to 2 mm, respectively. The manufacturing method of the polyester particle of Claim 7 . As a molten polyester, a polyester in a molten state obtained by performing an esterification reaction and / or a transesterification reaction of a dicarboxylic acid and / or an ester-forming derivative thereof and a diol, and further performing a melt polycondensation reaction is used as it is. method for producing polyester particles according to any one of claims 1 to 8, characterized in. The method for producing polyester particles according to any one of claims 1 to 9 , wherein the intrinsic viscosity of the polyester used in the step (1) is 0.20 to 0.40 dL / g. The method for producing polyester particles according to any one of claims 1 to 10 , wherein the polyester is polyethylene terephthalate and / or polybutylene terephthalate. Depending on the production method of the polyester particles according to any one of claims 1 to 11 to manufacture a port Riesuteru particles, process for producing a polyester resin particle, characterized by subjecting the polyester particles to a solid phase polycondensation reaction .