JP2000190325A - Apparatus and method for manufacturing thermoplastic resin pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pelletize a plurality of types of thermoplastic resins having different characteristics by a single cooling and cutting unit. SOLUTION: The apparatus for manufacturing a thermoplastic resin pellet comprises a cooling unit for cooling to solidify a strand group 3 obtained by discharging a thermoplastic resin of a molten state from a discharging unit 2, and a cutter 12 for cutting the cooled and solidified group 3 in the presence of the cooling water. The cooling unit has a cooling tray 4 of the unit 2 side and a conveyor belt 7 of the cutter 12 side. The tray 4 is inclined horizontally at a down gradient directly under the unit 2, disposed to an inlet of the belt 7, and has a cooling water, supplying unit directly under the unit 2 so that the water can flow from its upstream to its downstream. The belt 7 mounts the group 3 and the cooling water on its upper surface to convey them toward the cutter 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for producing thermoplastic resin pellets. More specifically, it is a device used for cooling and solidifying a strand group obtained by discharging a molten thermoplastic resin from a discharging device, cutting and pelletizing, and a single cooling and cutting device. Thermoplastic resin pellet manufacturing equipment capable of manufacturing high-quality thermoplastic resin pellets in high yields by enabling pelletization of multiple types of thermoplastic resins with different characteristics, eliminating the need for complicated replacement work of cooling equipment And a method of manufacturing the same.

[0002]

2. Description of the Related Art As a conventionally known method for producing thermoplastic resin pellets, a molten polymer is extruded into a strand form from a discharge portion (a die) provided in a discharge device, and the strand is taken out in a cooling water bath. After cooling and solidifying, it is pulled out of the cooling water and cut into pellets (cold cut method). Alternatively, the molten polymer is made to flow into a water-cooled tray in the form of strands, and the cooling water and the strands are simultaneously guided to the cutter section and the cooling water A method of cutting a strand underneath is exemplified.

However, when pelletizing by the above method, the length of the cooling water bath or the water-cooling tray is determined according to the melting point, crystallization temperature, glass transition temperature, etc. of the thermoplastic resin depending on the conditions. Need to be adjusted to be the same length.

For example, when cooling a strand of a thermoplastic resin having a low crystallization temperature, if the length of the water-cooled tray is too short, fused pellets or defective cutting pellets will be generated. In the case of cooling a thermoplastic resin strand having a high water content, if the length of the water-cooling tray is too long, the running of the strand is meandering or curved, the pellet shape becomes irregular, and there is a problem that the specification is increased.

[0005] When the amount of the fused pellets or the non-standardized pellets is increased, not only the pellet yield is deteriorated, but also problems such as poor biting of the raw material pellets in the subsequent extrusion and molding steps are caused. Will be.

In order to avoid such a problem, when a plurality of types of thermoplastic resins having different characteristics are to be pelletized by using the same pelletizer, each thermoplastic resin is suitable for each type. It was necessary to prepare several types of water-cooled trays having different lengths, and to replace the water-cooled tray each time the thermoplastic resin to be pelletized was changed.

[0007]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of studying to solve the problems in the prior art described above.

Accordingly, an object of the present invention is to make it possible to pelletize a plurality of types of thermoplastic resins having different characteristics by a single cooling and cutting device, to eliminate a complicated replacement operation of a cooling device, and to provide a high quality thermoplastic resin. An object of the present invention is to provide a thermoplastic resin pellet manufacturing apparatus and a manufacturing method capable of manufacturing resin pellets in high yield.

[0009]

In order to achieve the above-mentioned object, a method for producing thermoplastic resin pellets according to the present invention is directed to a method for manufacturing a thermoplastic resin pellet by discharging a group of strands obtained by discharging a molten thermoplastic resin from a discharge device. An apparatus used for cooling and solidifying, cutting and pelletizing, comprising a cooling section for cooling and solidifying the strand group, and a cutter section for cutting the cooled and solidified strand group in the presence of cooling water. The cooling unit includes a cooling tray on the discharge device side and a conveyor belt on the cutter unit side, and the water-cooled tray is inclined horizontally or directly below the discharge device and sloped downward, so that the entrance of the conveyor belt is And a cooling water supply / supply device provided immediately below the discharge device so that cooling water can flow from upstream to downstream thereof. Put the said strand group to the surface and the cooling water, characterized by being configured to be conveyed to the cutter unit direction.

In the method for producing thermoplastic resin pellets according to the present invention, the elevation angle of the water-cooled tray as viewed from the cutter section side is horizontal or 40 ° or less, and the elevation angle of the transport belt as viewed from the cutter section side is as described above. It is set to be equal to or less than the elevation angle of the water-cooled tray, the conveyor belt is a conveyor system that is not a nip system, and a scraper is arranged on the outlet side of the conveyor belt,
And it is preferable to provide an ejection device for ejecting a fluid in a gap between the scraper and the conveyance belt in a direction opposite to the traveling direction of the conveyance belt from below the gap, and these conditions are applied. Thus, it is possible to expect a better effect.

Further, the method for producing thermoplastic resin pellets of the present invention is characterized in that a group of strands obtained by discharging a molten thermoplastic resin from a discharge device is cooled, solidified, cut and pelletized. The present invention is characterized in that a cutter speed is set higher than a belt speed of a conveyor belt by using a thermoplastic resin pellet manufacturing apparatus.

When the apparatus for producing thermoplastic resin pellets has a scraper disposed at the exit side of the conveyor belt, an injection device provided in the gap between the scraper and the conveyor belt lowers the gap below the gap. And spraying a fluid, preferably water, against the traveling direction of the transport belt.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a thermoplastic resin pellet producing apparatus according to the present invention.

FIG. 1 is a schematic explanatory view showing an example of an apparatus for producing a thermoplastic resin pellet of the present invention.

In FIG. 1, the apparatus for producing thermoplastic resin pellets of the present invention comprises a reaction tank 1 having a discharge device 2 at the bottom.
A cooling unit composed of a water-cooled tray 4 and a transport belt 7;
It is roughly composed of a cutter unit 12.

The reaction tank 1 comprises a polymerization tank or a melting tank, and discharges a molten thermoplastic resin as a strand 3 from a discharge device 2 such as a base provided at a lower part.

The cooling section includes a cooling tray 4 on the side of the discharge device 2.
And the transport belt 7 on the cutter unit 12 side. The water-cooled tray 4 is inclined from the horizontal or directly below the discharge device 2 to a downward slope, and is disposed up to the entrance of the transport belt 7.
A cooling water supply / supply device 5 is provided immediately below the discharge device 2 so that cooling water can flow from upstream to downstream.

The transport belt 7 is configured so that the strand 3 and the cooling water are placed on the upper surface of the belt and can be transported toward the cutter unit 12.

In FIG. 1, reference numeral 6 denotes a spray nozzle provided as necessary to prevent the strand 3 from swinging and to assist in forming a cooling water flow film on the water cooling tray 4. Also, 8
Reference numeral 9 denotes a frame constituting the conveyor belt 7, and 9 denotes a motor for driving the conveyor belt 7.

At the outlet side of the conveyor belt 7, a scraper 1
0 is desirably provided, and when the scraper 10 is provided, the strand 3 can be efficiently separated from the transport belt 7 by the scraper 10. In this case, there is a gap between the scraper 10 and the conveyor belt 7, and the head of the strand smaller than this gap tends to be drawn into the gap by the cooling water accompanying the conveyor belt 7, and this state It is likely to occur at the start of discharge or when a strand break occurs. Therefore, in order to prevent this inconvenience, the cooling water injection device 11 is installed below the gap between the scraper 10 and the conveyor belt 7, and the cooling water jetting device 11 is drawn from below the gap against the traveling direction of the conveyor belt 7 by the fluid accompanying flow. It is desirable to inject a fluid, preferably a cooling water, to the extent that it can overcome.

The length of the water-cooled tray 4 is not particularly limited.
m to 8 m are preferable, and 1 to 5 m is more preferable.

The installation angle of the water-cooling tray 4 is not particularly limited, and may be horizontal or inclined downward from directly below the discharge device 2. The elevation angle of installation from the cutter unit 12 side is horizontal or 40 ° or less. It is desirable that the inclination is 3 ° or more. If the setting elevation angle is too large, the fluctuation due to the subsequent pulling of the conveyor belt 7 may increase, or the running of the strand 3 may become unstable.

It is essential to install a cooling water supply device 5 near the discharge device 2 of the water cooling tray 4. Although there is no particular limitation on the method of flowing the cooling water, it is preferable that the cooling water be supplied from the upstream portion of the water cooling tray 4. Furthermore, it is desirable to attach a spray nozzle 6 above the water-cooling tray 4 to spray cooling water for the purpose of supplementarily increasing the cooling effect or holding down the strand 3.

The transport belt 7 has a strand 3 on the upper part of the belt.
There is no particular limitation as long as it is a facility that puts and cooling water and sends it in the direction of the cutter unit 12, but as a preferred form, at least two rollers are provided, and at least one or more rollers are rotated by driving a motor or the like, There is a conveyor type in which a belt-like belt is rotated by a roller. Note that a nip method in which another transport belt is provided above the transport belt 7 for the purpose of holding the strands 3 may be considered. However, in this case, the winding of the strands 2 is caused. .

The installation angle of the conveyor belt 7 is not particularly limited, but is preferably equal to or less than the installation angle of the water cooling tray 4.

The cutter section 12 is not particularly limited as long as it can pelletize the strand 3 in the presence of cooling water, but preferably has a fixed blade and a rotary blade as a movable blade. The clearance between the fixed blade and the rotary blade is 0.1m
m or less, more preferably 0.06 mm or less,
Most preferably 0.04 mm or less.

When actually operating the thermoplastic resin pellet producing apparatus of the present invention having the above-described structure, first,
The molten thermoplastic resin polymerized in the reaction tank 1 is discharged in a strand shape onto the upper surface of the water-cooled tray 4 by the discharge device 2. At this time, the cooling water is supplied to the upper surface of the water cooling tray 4 from the cooling water supply device 5, and the strand 3
Is flowed downstream without being caught on the upper surface of the water cooling tray 4.

The strand 3 flowing on the water-cooled tray 4
Is transported together with the cooling water by the transport belt 7 in the direction of the cutter 12, and separated from the transport belt 7 by the scraper 10.

The strand 3 separated by the scraper 10 is guided to a cutter unit 12, cut into an appropriate shape by the cutter unit 12, pelletized, and sent to the next step.

In the method for cutting the thermoplastic resin pellets in this manner, the speed of the conveyor belt 7 is preferably 1 to 50 m / min faster than the linear speed of the strand 3 in front of the conveyor belt 7, and preferably 3 to 30 m / min. Minute speed is more preferable, and the absolute speed is preferably 50 to 300 m / min, and more preferably 70 to 250 m / min.

Here, in the method for producing thermoplastic resin pellets of the present invention, it is important that the cutter speed is higher than the speed of the conveyor belt. That is, the cutter speed is preferably 1 to 50 m / min faster than the conveyor belt speed, more preferably 3 to 30 m / min, more preferably 60 to 400 m / min as the absolute speed, and 75 to 400 m / min.
300 m / min is more preferred. If the cutter speed is lower than the speed of the conveyor belt, the strand group is wrapped around the drive belt, and pelletization cannot be performed normally, which is not preferable.

It is also preferable to provide a device for spraying a fluid from below the strand group for the purpose of preventing winding of the conveying belt portion between the conveying belt 7 and the cutter portion 12. The fluid may be a gas or a liquid. In the case of a gas, air, nitrogen, oxygen and the like are preferably used. In the case of a liquid, water and alcohol are preferably used, and air or water is most preferably used.

According to the apparatus and method for producing thermoplastic resin pellets of the present invention, using a single cooling and cutting device, setting conditions such as changing the speed of the conveyor belt and the inclination angle of the cooling tray. In other words, eliminating the complicated replacement work of the cooling device, polyamide-based resin, polyester-based resin, polyolefin-based resin, styrene-based resin,
It is possible to pelletize various thermoplastic resins with different properties such as ABS resin, polyphenylene sulfide resin, acrylic resin and various thermoplastic elastomers, and it is possible to produce high quality thermoplastic resin pellets in high yield. it can.

[0034]

The present invention will be described in more detail with reference to the following examples. The number of parts in the examples means parts by weight.

[Reference Example 1] (A) Preparation of catalyst solution 1,4-butanediol 9 was placed in a 200 ml Erlenmeyer flask.
0 parts by weight of tetra-n-butyl titanate (hereinafter referred to as TB
10 parts by weight (T) was heated to 100 ° C to 110 ° C on a hot plate while mixing and stirring. Thereafter, the temperature was adjusted to 100 ° C. and adjusted.

(B) Production of polybutylene terephthalate 755 parts of terephthalic acid, 1,4-butanediol 511
Parts and 0.450 parts of the catalyst solution prepared in (A) (T
(BT conversion) was charged into a reactor equipped with a rectification column, the inside of the reactor was replaced with nitrogen gas, and the esterification reaction was advanced while gradually raising the temperature from 180 ° C to 230 ° C. The generated water and tetrahydrofuran were purified. Distilled off via a distillation tower.

The obtained reaction product was transferred to an autoclave, and the same catalyst solution as used in the esterification reaction was added.
75 parts were added, the pressure was gradually reduced from normal pressure to 1 mmHg or less over 40 minutes, and the temperature was simultaneously raised to 247 ° C.
The polycondensation reaction was performed at a temperature of 1 ° C./1 mmHg or less until the specified torque was reached. The relative viscosity of the obtained polymer was 26.0 as measured with a 5% o-chlorophenol solution. Also,
The melting point measured by DSC is 230 ° C., and the crystallization temperature is 18
It was 0 ° C. This is called polymer A.

Reference Example 2 Production of Polyester Elastomer 439 parts of terephthalic acid, 190 parts of isophthalic acid, 1,4
-420 parts of butanediol, 181 parts of polytetramethylene ether glycol, and 0.450 parts (in terms of TBT) of the catalyst solution prepared in Reference Example 1 (A) were charged into a reactor equipped with a rectification column, and the inside of the reactor was charged. Replace with nitrogen gas, 180
The esterification reaction was advanced while gradually raising the temperature from 230C to 230C, and the generated water and tetrahydrofuran were distilled off via a rectification column.

The obtained reaction product was transferred to an autoclave, and the same catalyst solution as used in the esterification reaction was added.
75 parts were added, the pressure was gradually reduced from normal pressure to 1 mmHg or less over 40 minutes, and the temperature was simultaneously raised to 247 ° C.
The polycondensation reaction was performed at a temperature of 1 ° C./1 mmHg or less until the specified torque was reached. The relative viscosity of the obtained polymer was 26.0 as measured with a 5% o-chlorophenol solution. Also,
The melting point measured by DSC is 164 ° C, and the crystallization temperature is 90.
° C. This is called polymer B.

[Examples 1 and 2] The apparatus shown in FIG. 1 was placed immediately below the discharge device of each of the reaction tanks for the above-mentioned polymers A and B, and the elevation angle of the cooling tray, the trough length, the temperature of the cooling water, the conveyor belt The pellet length was changed by changing the belt length, speed, and cutter speed of the cutter section as shown in Table 1.

The clearance of the cutter blade is 0.0
It was adjusted to 3 mm.

Table 2 shows the evaluation results of the running property, pelletization yield, and pellet shape of the strand group at this time. In addition,
Each measuring method is as follows.

[Strandability of Strand Group] The state of the strand group in the trough was visually observed.

[Pelletization yield] 4 mesh (opening 4.7 m) based on the total amount of polymer discharged from the discharge device
m) The percentage of the yield of the pellets (% by weight) passed through the sieve was determined.

[Pellet shape] The obtained pellets were visually observed, and oblique cuts and the presence or absence of open-sphere pellets were observed.

[Comparative Examples 1 and 2] Pellets were formed in Examples 1 and 2 under the conditions shown in Table 1 except that the cooling section was a water-cooled tray only. Table 2 also shows the evaluation results of the running performance, pelletization yield, and pellet shape of the strand group in that case.

[0047]

[Table 1]

[Table 2] As is evident from the results in Table 2, the pellets obtained by the thermoplastic resin pellet manufacturing apparatus of the present invention showed a greater number of strand groups for a plurality of types of thermoplastic polymers than the method shown in Comparative Example. Run stably, the pelletization yield is high, and the pellet shape is good.

[0048]

As described above, according to the apparatus and method for manufacturing thermoplastic resin pellets of the present invention, a single cooling and cutting device is used, that is, a complicated replacement operation of the cooling device is eliminated. As a result, various thermoplastic resins having different properties can be pelletized, and high-quality thermoplastic resin pellets can be produced with high yield.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example of an apparatus for producing a thermoplastic resin pellet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Discharge device 3 Strand 4 Water cooling tray 5 Cooling water supply device 6 Spray nozzle 7 Transport belt 8 Frame 9 Drive motor 10 Scraper 11 Cooling water injection device 12 Cutter section

Continued on the front page F term (reference) 4F201 AC01 AK02 AR08 BA02 BC01 BC02 BC12 BC17 BC19 BL08 BL12 BL15 BM06 BQ23 BQ32 BQ57

Claims (8)

[Claims] An apparatus used for cooling and solidifying a strand group obtained by discharging a thermoplastic resin in a molten state from a discharging device to cut and pelletize the strand group, wherein the strand group is cooled and solidified. A cooling unit for performing, and a cutter unit for cutting the group of strands that have been cooled and solidified in the presence of cooling water, wherein the cooling unit includes a cooling tray on the discharge device side and a transport belt on the cutter unit side. The water-cooled tray is horizontally or inclined downwardly from directly below the discharge device, and is disposed up to the entrance of the conveyor belt, and is provided with a cooling water supply device immediately below the discharge device, from upstream to downstream thereof. Cooling water is allowed to flow, and the transport belt is configured such that the strand group and the cooling water are placed on the upper surface of the belt and can be transported toward the cutter unit. An apparatus for cutting thermoplastic resin pellets. 2. The elevation angle of the water-cooled tray viewed from the cutter section side is horizontal or 40 ° or less, and the elevation angle of the transport belt viewed from the cutter section side is set to be equal to or less than the installation elevation angle of the water-cooled tray. The thermoplastic resin pellet cutting device according to claim 1, wherein: 3. The thermoplastic resin pellet cutting apparatus according to claim 1, wherein the conveyor belt is a conveyor system other than a nip system. 4. The apparatus according to claim 1, wherein a scraper is disposed on an outlet side of the conveyor belt.
Item 5. The apparatus for cutting thermoplastic resin pellets according to item 1. 5. An apparatus according to claim 4, wherein an ejection device is provided in a gap between said scraper and said conveyance belt to eject a fluid from below said gap in a direction opposite to a traveling direction of said conveyance belt. An apparatus for cutting thermoplastic resin pellets as described above. 6. The method according to claim 1, wherein a strand group obtained by discharging the molten thermoplastic resin from the discharge device is cooled, solidified, cut and pelletized. A method for producing thermoplastic resin pellets, wherein a cutter speed is set higher than a belt speed of a conveyor belt using an apparatus. 7. The method according to claim 4, wherein the strands obtained by discharging the molten thermoplastic resin from the discharge device are cooled, solidified, cut and pelletized.
Using the manufacturing apparatus according to the above, by a spraying device provided in the gap between the scraper and the conveyor belt, a thermoplastic resin characterized by injecting a fluid from below the gap in a direction opposite to the traveling direction of the conveyor belt Method for producing pellets. 8. The method for producing thermoplastic resin pellets according to claim 7, wherein said fluid is water.