KR20180103751A - Method for preparing thermoplastic polymer particle - Google Patents

Abstract

The present invention provides a production method of thermoplastic polymer particles which comprises the following steps: supplying a thermoplastic polymer resin to an extruder and extruding the same; supplying the extruded thermoplastic polymer resin and air to a nozzle, bringing the thermoplastic polymer resin into contact with air to granulate the thermoplastic polymer resin, and then discharging the thermoplastic polymer resin particles; and supplying the discharged thermoplastic polymer particles to a cooler to cool the thermoplastic polymer particles, and then obtaining the cooled thermoplastic polymer particles. According to the present invention, the mixture of impurities except for the resin components in the thermoplastic polymer particles can be effectively prevented, and the obtained thermoplastic polymer particles can be widely utilized.

Description

METHOD FOR PREPARING THERMOPLASTIC POLYMER PARTICLE [0002]

The present invention relates to a process for producing thermoplastic polymer particles.

Polymer resins in particle form are widely used throughout the industry. These polymer resin particles are produced through a process of granulating the polymer resin raw material.

Generally, as a method of granulating the thermoplastic polymer resin, a pulverization method represented by freezing and crushing; A solvent dissolution method in which the compound is dissolved in a high-temperature solvent, cooled and then precipitated or dissolved in a solvent, and then a poor solvent is added to precipitate; And a melt-kneading method in which a thermoplastic resin and an emulsion resin are mixed in a mixer to form a composition having a thermoplastic resin in a dispersed phase in a continuous phase of a thermoplastic resin and a non-dispersible resin, and then the emulsion resin is removed to obtain thermoplastic resin particles.

There is a problem that it is difficult to ensure the uniformity of particles of the thermoplastic polymer resin particles produced when the particles are produced through the pulverization method. In addition, since liquid nitrogen is used during the cooling of the pulverization method, a high cost is required in comparison with the particle obtaining step. When a compounding process in which a pigment, an antioxidant or the like is added to the thermoplastic polymer resin material is added, productivity is lowered as compared with the continuous particle obtaining process because the process is performed in batch mode. In the case of producing particles through the solvent dissolution method and the melt-kneading method, other components such as a solvent can be detected as impurities in addition to the thermoplastic resin particles. In the case of incorporating impurities in the processing, it is not only difficult to produce pure particles of thermoplastic polymer resin purely, but also there is a high possibility that the physical properties and shape of the particles may be deformed, and it is difficult to finely control the particles.

Accordingly, there is a need in the art for a process for producing thermoplastic polymer particles which can solve the above-mentioned problems.

Japanese Patent Application Laid-Open No. 2001-288273 Japanese Patent Application Laid-Open No. 2000-007789 Japanese Laid-Open Patent Publication No. 2004-269865

The present invention relates to a method for producing thermoplastic polymer particles by extruding a thermoplastic polymer resin, bringing the extruded resin into contact with air and atomizing the thermoplastic polymer resin, and cooling the thermoplastic polymer particles to effectively prevent impurities from entering the particle except for the resin component, And to provide a method for producing thermoplastic polymer particles that can be controlled so as to have physical properties that can be utilized.

According to a first aspect of the present invention,

The present invention relates to a method for producing a thermoplastic resin composition, comprising: feeding a thermoplastic polymer resin to an extruder and extruding the same; Supplying an extruded thermoplastic polymer resin and air to a nozzle, bringing the thermoplastic polymer resin into contact with air to granulate the thermoplastic polymer resin, and then discharging the thermoplastic polymer resin particles; And feeding the discharged thermoplastic polymer particles to a cooler to cool the thermoplastic polymer particles, and then obtaining cooled thermoplastic polymer particles.

In one embodiment of the present invention, when the extruded thermoplastic polymer resin and the air are supplied to the nozzle, air is supplied to the central part and the outer part based on the cross section of the nozzle, and the extruded thermoplastic polymer resin is supplied to the center And the outer frame portion.

In one embodiment of the present invention, the cross-sectional area ratio of the extruded thermoplastic polymer resin supplied between the center portion and the outer frame portion, to which air supplied to the outer frame portion and air are supplied, is 1: 1 to 10: 1.

In one embodiment of the present invention, the distal end of the nozzle is maintained at a temperature calculated by the following equation.

[formula]

Terminal temperature = glass transition temperature (T _g ) + (thermal decomposition temperature (T _d ) - glass transition temperature (T _g )) × A

In the above formula, the glass transition temperature and the thermal decomposition temperature are values for the thermoplastic polymer, and A is 0.5 to 1.5.

The method for producing thermoplastic polymer particles according to the present invention can uniformly and effectively control the physical properties such as the size and shape of the particles without the addition of the thermoplastic polymer resin as a raw material and other components other than air.

Therefore, the particles produced by the production method according to the present invention are effectively processed when the particles are applied to products in various fields, because the impurities other than the thermoplastic polymer are effectively excluded from the particles and the inner and the inner physical properties are improved.

1 is a process flow chart schematically showing a method for producing thermoplastic polymer particles according to the present invention.
FIG. 2 is a cross-sectional view of a nozzle discharge portion showing a supply position of a thermoplastic polymer resin and air to a nozzle according to an embodiment of the present invention. FIG.

The embodiments provided in accordance with the present invention can be all achieved by the following description. It is to be understood that the following description is of a preferred embodiment of the present invention and that the present invention is not necessarily limited thereto.

In the following description, for the numerical range, the expressions "to" are used to mean both of the upper and lower limits of the range. When the upper and lower limits are not included, Quot; over, "" below," or "abnormal"

The present invention provides a method for producing a thermoplastic polymer particle in which a thermoplastic polymer resin whose physical properties are controlled by temperature and pressure is granulated by bringing it into contact with air, without adding any additional components such as a solvent. Fig. 1 schematically shows a process flow chart for the above manufacturing method. The method comprises: (S100) supplying a thermoplastic polymer resin to an extruder and extruding the extruded thermoplastic polymer resin; Supplying the extruded thermoplastic polymer resin and air to a nozzle, bringing the thermoplastic polymer resin into contact with air to granulate the thermoplastic polymer resin, and discharging the thermoplastic polymer resin particles (S200); And supplying the discharged thermoplastic polymer particles to a cooler to cool the thermoplastic polymer particles, and then obtaining cooled thermoplastic polymer particles (S300). Each step of the above manufacturing method will be described in detail below.

In order to produce the thermoplastic polymer particles according to the present invention, first, a thermoplastic polymer resin as a raw material is fed to an extruder and extruded. By extruding the thermoplastic polymer resin, the thermoplastic polymer resin has properties suitable for particle processing in the nozzle. The thermoplastic polymer resin used as a raw material is not particularly limited as long as it is a material capable of being granulated according to the production method of the present invention, but it is preferable that the thermoplastic polymer resin has a weight average molecular weight of 10,000 to 200,000 g / mol in consideration of proper physical properties of the produced particles have. According to an embodiment of the present invention, the thermoplastic polymer resin may be selected from the group consisting of polylactic acid (PLA), thermoplastic polyurethane (TPU), polyethylene (PE), polypropylene (PP), poly Polyether sulfone, poly (methyl methacrylate) (PMMA), ethylene vinyl alcohol copolymer (EVOH), and combinations thereof. .

The extruder to which the thermoplastic polymer resin is supplied heats and pressurizes the thermoplastic polymer resin to control physical properties such as viscosity of the thermoplastic polymer resin. The type of the extruder is not particularly limited as long as it is possible to control the physical properties suitable for granulation in the nozzle. According to one embodiment of the present invention, the extruder can be used with a biaxial screw extruder for efficient extrusion. The inside of the extruder may be maintained at 150 to 450 캜, preferably 170 to 400 캜, more preferably 200 to 350 캜. If the internal temperature of the extruder is less than 150 ° C, the viscosity of the thermoplastic polymer resin is high, which is not suitable for the granulation in the nozzle, and the flowability of the thermoplastic polymer resin in the extruder is low. If the internal temperature of the extruder is higher than 450 ° C., the flowability of the thermoplastic polymer resin is high and efficient extrusion is possible. However, it is difficult to control fine physical properties when the thermoplastic polymer resin is granulated in the nozzle.

The amount of the thermoplastic polymer resin to be extruded can be easily controlled by controlling the physical properties of the thermoplastic polymer resin in consideration of the size of the extruder. According to one embodiment of the present invention, the thermoplastic polymer resin is extruded at a rate of 1 to 10 kg / hr. The viscosity of the extruded thermoplastic polymer resin may be 0.5 to 20 Pa · s, preferably 1 to 15 Pa · s, more preferably 2 to 10 Pa · s. If the viscosity of the thermoplastic polymer resin is less than 0.5 Pa · s, it is difficult to process particles in the nozzle. If the viscosity of the thermoplastic polymer resin is more than 20 Pa · s, the flowability of the thermoplastic polymer resin in the nozzle is low. The temperature of the extruded thermoplastic polymer resin may be 150 to 450 캜.

The thermoplastic polymer resin extruded from the extruder is supplied to the nozzle. Along with the thermoplastic polymer resin, air is also supplied to the nozzles. The air contacts the thermoplastic polymer resin in the nozzle to granulate the thermoplastic polymer resin. The nozzle is supplied with high-temperature air so that the properties of the thermoplastic polymer resin can be properly maintained. According to an embodiment of the present invention, the temperature of the air may be 250 to 600 ° C, preferably 270 to 500 ° C, and more preferably 300 to 450 ° C. When the temperature of the air is lower than 250 ° C or higher than 600 ° C, the physical properties of the surface of the thermoplastic polymer resin in contact with air can be changed to an undesirable direction when the thermoplastic polymer particles are produced. In particular, when the temperature of the air exceeds 600 ° C, excessive heat is supplied to the contact surface with the air, and the decomposition of the polymer may occur on the surface of the particles.

The thermoplastic polymer resin and air supplied to the nozzle are set at the supply position so that the thermoplastic polymer particles can have an appropriate size and shape and the formed particles can be evenly dispersed. Fig. 2 shows a cross-sectional view of the nozzle discharging portion. The supplying position of the thermoplastic polymer resin and air according to one embodiment of the present invention will be described in detail with reference to Fig. For the sake of specific explanation in the present specification, the positions of the nozzles are expressed as " injection portion ", " discharge portion ", and " distal portion ". The " injection part " of the nozzle means the position where the nozzle starts, and the " discharge part " of the nozzle means the position where the nozzle ends. The " end portion " of the nozzle means the position from the two thirds of the nozzle to the discharge portion. Here, the zero point of the nozzle is the injection part of the nozzle, and one point of the nozzle is the discharge part of the nozzle.

As shown in Fig. 2, the thermoplastic polymer resin and the cross section perpendicular to the flow direction of air are circular. The air is supplied through a first air flow (40) supplied to the center of the circle and a second air flow (20) supplied to the circular outer frame. The thermoplastic polymer resin flows through the first air flow (40) Is supplied between the second air flow (20). (The thermoplastic polymer resin flow 30, the first air flow 40 and the second air flow 20) from the time when the thermoplastic polymer resin and air are supplied to the injection portion of the nozzle to just before the discharge portion of the nozzle And is separated by the structure inside the nozzle. Immediately before the discharge portion of the nozzle, the thermoplastic polymer resin flow and the second air flow are merged to make air contact with the thermoplastic polymer resin, whereby the thermoplastic polymer resin is granulated. Alternatively, the first air flow is separated by a nozzle internal structure from the thermoplastic polymer resin flow and the second air flow until the thermoplastic polymer resin and air are discharged from the nozzle. The first air flow serves to prevent the particles of the thermoplastic polymer resin that have been granulated by the second air flow from adhering to the discharge portion of the nozzle and disperse the discharged particles evenly before being supplied to the cooler after discharge from the nozzle .

The thermoplastic polymer resin extruded from the extruder is supplied to the above-mentioned position of the nozzle, and the flow rate of the air supplied to the nozzle can be adjusted according to the flow rate of the extruded thermoplastic polymer resin. According to one embodiment of the present invention, the air is supplied to the nozzle at a flow rate of 1 to 300 m ³ / hr, preferably 30 to 240 m ³ / hr, more preferably 60 to 180 m ³ / hr. Within the flow rate range of the air, the air is separately supplied into the first air flow and the second air flow. As described above, the thermoplastic polymer resin is granulated by the second air flow, in which the ratio of the thermoplastic polymer resin to the second air flow as well as the temperature of the second air flow can determine the physical properties of the particles. According to one embodiment of the present invention, the cross-sectional area ratio of the thermoplastic polymer resin to the second air flow is 1: 1 to 10: 1, preferably 1.5: 1 to 8: 1, more preferably May be from 2: 1 to 6: 1. When the ratio of the thermoplastic polymer resin to the second air flow is controlled within the above range, the thermoplastic polymer particles of appropriate size and shape having high usability can be produced.

Since the thermoplastic polymer resin in the nozzle is granulated, the inside of the nozzle is adjusted to a temperature suitable for the thermoplastic polymer resin to be granulated. Since the rapid temperature rise can change the structure of the polymer in the thermoplastic polymer resin, the temperature from the extruder to the discharge portion of the nozzle can be raised stepwise. Therefore, the internal temperature of the nozzle is set to be higher than the internal temperature of the extruder on average. Since the temperature for the distal end of the nozzle is separately defined below, the internal temperature of the nozzle herein means an average temperature of the remaining part of the nozzle except for the distal end of the nozzle, unless otherwise specified. According to one embodiment of the present invention, the interior of the nozzle may be maintained at 250 to < RTI ID = 0.0 > 450 C. < / RTI > If the internal temperature of the nozzle is less than 250 ° C., sufficient heat is not transferred to the thermoplastic polymer resin to satisfy the properties during the granulation. If the internal temperature of the nozzle exceeds 450 ° C., excessive heat is supplied to the thermoplastic polymer resin, Can be changed.

The distal end of the nozzle may be maintained at a temperature higher than the average temperature inside the nozzle to improve the extrinsic and intrinsic properties of the resulting particle. The temperature at the distal end of the nozzle may be determined between the glass transition temperature (T _g ) and the thermal decomposition temperature (T _d ) of the thermoplastic polymer, and may be determined in accordance with the following equation.

[formula]

Terminal temperature = glass transition temperature (T _g ) + (thermal decomposition temperature (T _d ) - glass transition temperature (T _g )) × A

Here, A may be 0.5 to 1.5, preferably 0.65 to 1.35, more preferably 0.8 to 1.2. If A is less than 0.5, it is difficult to expect the improvement of the external and internal physical properties of the particles due to the temperature rise of the nozzle. If A is more than 1.5, the heat substantially transferred to the thermoplastic polymer at the end of the nozzle is excessively increased The structure of the thermoplastic polymer can be modified. The glass transition temperature and the thermal decomposition temperature may vary depending on the kind of polymer, degree of polymerization, structure, and the like. According to one embodiment of the present invention, a thermoplastic polymer having a glass transition temperature of -40 to 250 캜 and a thermal decomposition temperature of 270 to 500 캜 may be used. Since the distal end of the nozzle is maintained above the average temperature of the nozzle, additional heating means may be provided at the distal end of the nozzle, as the case may be.

The thermoplastic polymer particles discharged from the nozzle are supplied to the cooler. The nozzle and the cooler can be positioned apart, in which case the discharged thermoplastic polymer particles are primarily cooled by ambient air before being fed to the cooler. In the nozzle, not only the thermoplastic polymer particles but also the high-temperature air are discharged together. By separating the nozzle and the cooler, the high-temperature air can be discharged to the outside rather than the cooler. According to one embodiment of the present invention, the cooler is positioned with the nozzle at a distance of 100 to 500 mm, preferably 150 to 400 mm, more preferably 200 to 300 mm. When the distance is shorter than the above distance, a large amount of high-temperature air is injected into the cooling chamber to lower the cooling efficiency. When the distance is longer than the distance, the amount of cooling by the ambient air becomes large, Is not achieved. In addition, when the thermoplastic polymer particles are discharged from the nozzle, the spray angle may be in the range of 10 to 60 °. When the thermoplastic polymer particles are discharged at the corresponding angle, the effect according to the separation between the nozzle and the cooler can be doubled.

The cooler can cool the thermoplastic polymer particles by supplying low-temperature air into the cooler to bring the thermoplastic polymer particles into contact with the air. The low-temperature air forms a rotating air stream in the cooler, and the residence time of the thermoplastic polymer particles in the cooler can be sufficiently secured by the rotating air stream. The flow rate of the air supplied to the cooler can be adjusted according to the supply amount of the thermoplastic polymer particles, and according to one embodiment of the present invention, the air can be supplied to the cooler at a flow rate of 1 to 10 m ³ / min. The air may preferably have a temperature of -30 to -20 占 폚. By supplying the cryogenic air into the cooler in comparison with the thermoplastic polymer particles supplied to the cooler, the thermoplastic polymer particles are rapidly cooled, and the internal structure of the high temperature thermoplastic polymer particles can be appropriately maintained. When the thermoplastic polymer particles are actually applied for the production of a product, they are reheated again, and the reheated thermoplastic polymer has properties favorable to processing. The thermoplastic polymer particles cooled by the low-temperature air are cooled down to 40 ° C or lower, and the discharged particles are collected through a cyclone or a bag filter.

The method for producing thermoplastic polymer particles according to the present invention can uniformly and effectively control the physical properties such as the size and shape of the particles without the addition of the thermoplastic polymer resin as a raw material and other components other than air. Therefore, the particles produced by the production method according to the present invention are effectively processed when the particles are applied to products in various fields, because the impurities other than the thermoplastic polymer are effectively excluded from the particles and the inner and the inner physical properties are improved.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the present invention is not limited thereto.

Example

Example  1: According to the manufacturing method of the present invention Polylactic acid  Manufacturing of particles

Polylactic acid (Natureworks, 2003D, Mw: about 200,000g / mol, a glass transition temperature (T _g): about 55 ℃, the thermal decomposition temperature (T _d): about 300 ℃) to 100% by weight twin screw extruder (diameter (D ) = 32 mm, length / diameter (L / D) = 40). The biaxial screw extruder was set to a temperature condition of about 220 ° C and an extrusion amount of about 5 kg / hr to conduct extrusion. The extruded polylactic acid resin has a viscosity of about 10 Pa · s and the extruded polylactic acid resin is applied to a nozzle set at an internal temperature of about 300 ° C. and a terminal temperature of about 350 ° C. Respectively. In addition, air at about 350 캜 was supplied to the nozzle at a flow rate of about 1 m ³ / min. The air was supplied to the central portion and the outer frame portion of the nozzle cross section, and the extruded polylactic acid resin was supplied between the central portion and the outer frame portion of the nozzle to which the air was supplied. The cross-sectional area ratio of the extruded polylactic acid resin supplied between the air supplied to the outer portion and the air supplied to the outer portion was about 4.5: 1. The polylactic acid resin supplied to the nozzle was atomized by contact with hot air, and the atomized particles were ejected from the nozzle. The spray angle from the nozzle was about 45 °, and the sprayed particles were supplied to a cooling chamber (diameter (D) = 1,100 mm, length (L) = 3,500 mm) spaced about 200 mm from the nozzle. Also, before the sprayed particles were supplied, the cooling chamber was adjusted so as to form a rotating air stream by injecting air at about -25 DEG C at a flow rate of about 6 m < ³ > / min. Particles cooled sufficiently below 40 캜 in the cooling chamber were collected through a cyclone or bag filter.

Example  2: Preparation of thermoplastic polyurethane particles according to the production method of the present invention

The thermoplastic polyurethane resin as a starting material a ^{(Lubrizol, Pearlthane TM D91M80, Mw} : about 160,000g / mol, a glass transition temperature (T _g):: about -37 ℃, the thermal decomposition temperature (T _d) of about 290 ℃) 100% by weight The particles were produced in the same manner as in Example 1, except that they were used.

Comparative Example  1: According to freezing grinding system Polylactic acid  Manufacturing of particles

The same polylactic acid resin as in Example 1 was fed through a hopper into a screw feeder. The moisture was removed while moving the raw material through the screw, and then the raw material was introduced into a grinder supplying liquid nitrogen at -130 ° C. A pin crusher-type crusher was used as the crusher. The particle size was controlled via a pulverizing sizing pin. The atomized particles were collected through a crusher and collected through a cyclone.

Experimental Example  1: Evaluation of physical properties of particles

The physical properties of the particles prepared according to Examples 1 and 2 and Comparative Example 1 were measured and are shown in Table 1 below.

Average particle diameter (占 퐉) ^{1 )} Aspect ratio ^{2 )} Sphericity ^{3 )} Example 1 14.2 1.02 + - 0.01 0.98 ± 0.01 Example 2 102.6 1.01 + - 0.01 0.99 ± 0.01 Comparative Example 1 10.8 1.43 + - 0.41 0.74 + 0.18

1) Using an ImageJ (National Institutes of Health (NIH)) at room temperature, calculate the average particle size of the powder aggregate. The long axis of each particle was taken as the particle diameter, and the number average value of each particle diameter was taken as the average particle diameter for the aggregate of particles.

2), 3) Image processing using the same apparatus - Binary images were converted to binary images, and the degree of sphericalization of individual particles was numerically analyzed. The formation of particles was analyzed and the aspect ratio and sphericity were derived by equations 1 and 2.

According to the above Table 1, the thermoplastic polymer particles according to Examples 1 and 2 have a shape approximate to a sphere by measuring an aspect ratio and a degree of sphericity close to 1, while the thermoplastic polymer particles according to Comparative Example 1 have an aspect ratio and a spherical shape The degree of haze was measured as a value slightly different from 1, and it did not have a shape close to the spherical shape.

As in Comparative Example 1, the thermoplastic polymer particles produced by the conventional freezing and pulverizing method do not satisfy the aspect ratio and sphericity close to the spherical shape, so that the thermoplastic polymer particles in the future can be handled in comparison with the thermoplastic polymer particles of Examples 1 and 2 It is not easy.

Experimental Example  2: DSC  analysis

The particles prepared according to Examples 1 and 2 and Comparative Example 1 were subjected to DSC analysis and shown in Table 2 below. Specifically, the DSC curve was obtained by raising the temperature from 0 ° C to 200 ° C at a heating rate of 10 ° C / min using a differential scanning calorimeter (DSC, Perkin-Elmer, DSC8000). The difference between the glass transition temperature (T _g ), the melting point (T _m ), the cold crystallization temperature (T _cc ) and the heat absorption amount (ΔH 1) and the calorific value (ΔH 2) was derived from each DSC curve.

T _g (° C) T _m (° C) T _cc (캜) ? H1 -? H2 (J / g) Example 1 55 140 98 36 Example 2 -37 136 34 6 Comparative Example 1 59 146 - 42

According to Table 2, the thermoplastic polymer particles of Example 1 exhibited a peak of a cold crystallization temperature at 98 ° C, and the thermoplastic polymer particles of Example 2 showed a cold crystallization temperature peak at 34 ° C, It was confirmed that the temperature of the thermoplastic polymer particles did not show such a cold crystallization temperature peak.

Further, in the case of Embodiment 1, the difference between the heat absorption amount ΔH1 and the heat generation amount ΔH2 is about 36 J / g. In Embodiment 2, the difference between the heat absorption amount ΔH1 and the heat generation amount ΔH2 And the difference is about 6 J / g. It was confirmed that the difference between the heat absorption amount (ΔH1) and the heat generation amount (ΔH2) was about 42 J / g in the case of Comparative Example 1, unlike in Example 1. It is understood that the polylactic acid particles of Example 1 have a relatively high calorific value because they have a characteristic of generating heat before the particles are melted by the cold crystallization phenomenon.

When the thermoplastic polymer particles have a cold crystallization temperature peak as in Examples 1 and 2 and the heat treatment is performed using such particles, the thermoplastic polymer particles have an advantage that they can be processed at a lower temperature than the processing temperature of the thermoplastic polymer particles of Comparative Example 1 .

Comparative Example  2: Depending on the solvent polymerization method Polylactic acid  Manufacturing of particles

Lactic acid was added to the xylene solvent, and the mixture was stirred. Then, a tin-based catalyst and a polyol were charged and polymerized at a temperature of about 140 ° C. The polymer was dissolved in chloroform, precipitated in methanol, and dried to finally produce polylactic acid particles having a size of 10 mu m.

Comparative Example  3: Preparation of Thermoplastic Polyurethane Particles by Solvent Polymerization

An ester or ether-based polyol was added to the dimethylformamide solvent and stirred, and then a diisocyanate was added to synthesize a prepolymer. Thereafter, a reactive mono-molecular diol or a diamine-based chain extender was added at a temperature of 80 ° C to finally produce a thermoplastic polyurethane particle having a size of 400 μm.

Experimental Example  3: Analysis of impurities in particles

The impurity contents of the particles prepared according to Example 1 and Comparative Examples 2 and 3 were analyzed and are shown in Table 3 below. Specifically, the residual solvent in the particles was measured by means of a GC / FID apparatus (manufacturer: Agilent, model name: 7890A) and heavy metals in the particles were measured by ICP / MS apparatus (manufacturer: Perkinelmer, model name: Nexion 300). The impurity content in Table 3 is the sum of the residual solvent content in the particles and the heavy metal content.

Content of impurities (ppm) Example 1 3 Comparative Example 2 61 Comparative Example 3 53

According to Table 3, the particles of Comparative Examples 2 and 3 had a significantly higher content of impurities as compared with the particles of Example 1 due to residual solvents in the particles and the like because solvents were used in the production of the particles. On the other hand, the particles of Example 1 had almost no impurities such as residual solvent except for a trace amount of impurities introduced from the device during the production of the particles.

It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

10: Nozzles
20: second air flow
30: Thermoplastic polymer resin flow
40: first air flow

Claims (12)

(1) feeding a thermoplastic polymer resin to an extruder and extruding the same;
(2) feeding the extruded thermoplastic polymer resin and air to a nozzle, bringing the thermoplastic polymer resin into contact with air to granulate the thermoplastic polymer resin, and then discharging the thermoplastic polymer resin particles; And
(3) feeding the discharged thermoplastic polymer particles to a cooler to cool the thermoplastic polymer particles, and then cooling the thermoplastic polymer particles to obtain cooled thermoplastic polymer particles.
The method according to claim 1,
Wherein the inside of the extruder is maintained at 150 to 450 ° C in the step (1).
The method according to claim 1,
Wherein the extruded thermoplastic polymer resin supplied to the nozzle in the step (2) has a melt viscosity of 0.5 to 20 Pa · s.
The method according to claim 1,
The thermoplastic polymer resin extruded in the step (2) is supplied to the nozzle at a flow rate of 1 to 10 kg / hr, and the air is supplied to the nozzle at a flow rate of 1 to 300 m ³ / hr. .
The method according to claim 1,
Wherein the air is supplied to the nozzle at a temperature of 250 to 600 ° C in the step (2).
The method according to claim 1,
In the step (2), air is supplied to the center part and the outer frame part based on the cross section of the nozzle, and the extruded thermoplastic polymer resin is supplied between the central part and the outer part to which air is supplied. Way.
The method of claim 6,
Sectional area ratio of the extruded thermoplastic polymer resin supplied between the center portion and the outer frame portion, to which air supplied to the outer frame portion and the air are supplied, based on the cross section at the discharge portion of the nozzle in the step (2) : 1. ≪ / RTI >
The method according to claim 1,
Wherein the inside of the nozzle is maintained at 250 to 450 ° C in the step (2).
The method of claim 8,
Wherein the end portion of the nozzle is maintained at a temperature calculated by the following equation in the step (2): < EMI ID =

[formula]
Terminal temperature = glass transition temperature (T _g ) + (thermal decomposition temperature (T _d ) - glass transition temperature (T _g )) × A

In the above formula, the glass transition temperature and the thermal decomposition temperature are values for the thermoplastic polymer, and A is 0.5 to 1.5.
The method according to claim 1,
Wherein the ejection angle of the thermoplastic polymer resin in the nozzle in the step (2) is 10 to 60 °.
The method according to claim 1,
Wherein the cooler is spaced apart from the discharging portion of the nozzle and the discharged thermoplastic polymer particles are primarily cooled by ambient air before the cooler is charged.
The method of claim 11,
Wherein the inside of the cooler is maintained at -30 to -20 占 폚 in the step (3).

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