JP6317223B2 - Resin pellet manufacturing method and resin pellet manufacturing apparatus - Google Patents

Description

  The present invention relates to a resin pellet manufacturing method and a resin pellet manufacturing apparatus, and is suitable for reducing defective pellets.

  Resin pellets such as engineering plastics are manufactured through a process of extruding a material resin with an extruder. In this step, the resin melted by heating is extruded from an extrusion molding die attached to the extrusion molding machine. The extrusion die is composed of a die head and a die plate. The die head is a portion where the flow path of the resin extruded from the extruder expands, and the die plate is attached to the plurality of die head portions and has a plurality of discharge ports through which the molten resin is discharged.

  Patent Document 1 below describes such an extrusion die. In Patent Document 1, the die head is referred to as an adapter portion, and the die plate is referred to as a die head portion. This extrusion die has 5 to 12 discharge ports. However, the number of protrusions tends to increase due to demands for improving production efficiency. Patent Document 2 below describes an extrusion die having 20 or more projecting ports. In this extrusion die, the width expansion rate of the flow path in the die head is increased in order to increase the number of discharge ports. On the other hand, since the sudden widening of the flow path causes variations in the diameter of the resin discharged from each discharge port, the length of the widened part where the flow path widens and the widening inclination angle of the widened part are in an appropriate range. It is said that.

JP 2007-320056 A Japanese Patent Laid-Open No. 2006-001015

  However, as in Patent Document 2, it was found that when the widening ratio is large due to the large number of discharge ports, the burned pellets containing burned resin are likely to be mixed in the manufactured pellets. These burned pellets include those in which the burned resin is contained in a normal resin to be discharged in a black dot shape, and those that are burned and covered with a thin layer of normal resin.

  Burnt pellets are one of the causes of resin burning in the flow path of the extrusion die. This burn is thought to be promoted as follows. In the production of pellets, the resin that becomes the pellets may contain an epoxy-based additive as a stabilizer or a flame retardant. This epoxy-type additive reacts with the metal (iron) which comprises an extrusion die, and is easy to adhere to the inner wall of an extrusion die. The epoxy additive adhering to the inner wall and the resin as the main component of the pellet cause a crosslinking reaction to increase the viscosity. For this reason, the resin stays and accumulates heat, burns, and a part of the burned resin is peeled off, which causes the burned pellets.

  Then, this invention tends to provide the resin pellet manufacturing method and resin pellet manufacturing apparatus which can reduce a burning pellet.

This invention for solving the said subject is related with the resin pellet manufacturing method which extrudes resin from the die for extrusion molding, and the resin pellet manufacturing apparatus which extrudes resin from the die for extrusion molding. In the resin pellet manufacturing method and the resin pellet manufacturing apparatus, the extrusion die includes an inlet into which molten resin flows, and 20 to 60 die nozzles that discharge the resin and are arranged at predetermined intervals. And a resin flow path is formed in a direction adjacent to the die nozzle between the inlet and the die nozzle and the resin flows in the direction in which the resin flows, and in front of the die nozzle A widened portion that suppresses the spread of the resin flow path, the volume from the widened portion to the front of the die nozzle is Vcm ^3, and the amount per unit time that the resin is discharged from the die nozzle is Qcm ³ / second In case,
1.0Q ≦ V ≦ 3.0Q
It is characterized by satisfying.

In a resin pellet manufacturing apparatus that discharges resin as pellets from 20 to 60 discharge ports, the resin is flowed while spreading in the direction in which the die nozzles are arranged in the widened portion of the extrusion die. In the extrusion die having such a structure, the resin flow path is prevented from spreading before the die nozzle in the widened portion in order to stabilize the discharge of the resin. However, burning tends to occur at a site where the resin flow path changes from a state where the resin flow path expands to a state where the expansion is suppressed. Therefore, in the resin pellet manufacturing method and the resin pellet manufacturing apparatus of the present invention, the volume Vcm ³ from the widened portion in the resin flow path of the extrusion molding die to the front of the die nozzle and the discharge amount Qcm ³ / sec of resin per unit time are as follows. The above formula is satisfied. That is, the average time from the resin flowing into the widened portion to reaching the front of the die nozzle from the extrusion die is set to 1 second to 3 seconds. It has been found that the burn can be reduced by adjusting the time from when the resin flows into the widened portion to when the resin is discharged from the extrusion die. The reason for this is not clear, but can be considered as follows. That is, in the case of an extrusion die having a scale of 20 to 60 die nozzles, the epoxy resin contained in the resin if the time during which the resin stays from the widened portion to the outlet of the die nozzle is 3 seconds or more Additives and the like tend to react with the metal constituting the extrusion die. Therefore, the occurrence of burning at the above-mentioned part can be reduced by setting the time for the resin to remain in the resin flow path within 3 seconds. On the other hand, in an extrusion die having a scale of 20 to 60 die nozzles, the time that the resin stays in the widened portion and the die nozzle is shorter than 1 second means that the resin flows at a high speed. For this reason, it is considered that the resin generates heat due to the shear resistance of the resin, and this heat raises the temperature of the extrusion die and causes burning. Therefore, when the time for the resin to remain in the flow path is 1 second or more, the burn at the above-mentioned part can be reduced.

  In this way, the residence time of the resin from the widened portion of the extrusion die having a scale of 20 to 60 to the front of the nozzle is set to 1 second or more and 3 seconds or less, so that the burnt pellets Can be reduced.

Further, when the sum of the distances between the centers of the discharge ports adjacent to each other is Lcm,
2 cm ² ≦ V / L ≦ 6 cm ²
It is preferable to satisfy.

  In the widened portion of a general extrusion molding die, fluctuations in the flow path height in the direction perpendicular to the resin flow direction and the discharge port arrangement direction are suppressed. Therefore, V / L generally represents the product of the channel height in the widened portion and the channel length, which is the length of the resin flowing in the widened portion. As described above, in the extrusion die having a scale of 20 to 60 die nozzles, the flow path length is correspondingly long. Therefore, when V / L satisfies the above equation, the flow rate of the resin in the widened portion can be more appropriate, and the burn in the widened portion can be further suppressed.

  The resin may contain 0.1 mol / kg or less of epoxy groups. Further, the resin may contain 0.1 mol / kg or less of carboxylic acid anhydride.

  When these resins are used, the reaction with the metal is likely to occur. Therefore, the average time that the resin stays in the flow path of the extrusion die is set to 1 to 3 seconds. Can be reduced.

  As described above, according to the resin pellet manufacturing method and the resin pellet manufacturing apparatus of the present invention, burnt pellets can be reduced.

It is a figure which shows the resin pellet manufacturing apparatus which concerns on embodiment of this invention. It is sectional drawing in the orthogonal | vertical direction of the die for extrusion molding of FIG. 1, and its vicinity. It is sectional drawing in the horizontal direction of the die for extrusion molding of FIG. 1, and its vicinity. It is a figure which planarly views the discharge port of the die for extrusion molding. It is a figure which carries out planar view of the discharge outlet of the die for extrusion molding in case a die nozzle is arranged in a straight line form.

  Hereinafter, preferred embodiments of a resin pellet manufacturing method and a resin pellet manufacturing apparatus according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a resin pellet manufacturing apparatus according to an embodiment of the present invention. In addition, in FIG. 1, the main structures of the resin pellet manufacturing apparatus are shown, and other structures are omitted. As shown in FIG. 1, the resin pellet manufacturing apparatus includes an extruder 1 and an extrusion die 2 as main components.

  The extruder 1 has a cylinder 11, a hopper 12, a flange 14, and a pair of screws 15 arranged in a housing as main components. In FIG. 1, only one of the pair of screws 15 is shown.

  A part of the cylinder 11 is formed with an opening, and the hopper 12 is provided so that a resin can be poured from the opening. Also, the pair of screws rotate about the axis and push toward the extrusion die 2 while kneading the molten resin around the screw 15. Accordingly, a resin flow path is formed between the screw 15 and the cylinder 11. By adjusting the amount of raw material supplied to the hopper 12, the amount per unit time that the resin is extruded is adjusted. Also, the cylinder 11 is formed with a gas vacuum opening 13 for sucking out gas generated from the resin or the like, or a base gas mixed with the resin. Although not particularly illustrated, the cylinder 11 may be formed with other openings for adding additives and fillers. Further, a flange 14 is fixed to an end portion on the discharge side of the cylinder 11. The screw 15 extends into the resin flow path of the flange 14.

  As shown in FIG. 1, the extrusion die 2 is fixed to the extruder 1. 2 is a vertical sectional view of the extrusion die 2 of FIG. 1 and the vicinity thereof, and FIG. 3 is a horizontal sectional view of the extrusion die 2 of FIG. 1 and the vicinity thereof. As shown in FIGS. 2 and 3, the extrusion die 2 includes a die head 20 and a die plate 30.

  The die head 20 is formed with a through hole, and this through hole is a resin flow path. The die head 20 is fixed to the extruder 1 as described above with the resin flow path of the die head 20 connected to the resin flow path in the flange 14 of the extruder 1. Accordingly, the molten resin extruded from the extruder 1 flows into the resin flow path of the die head 20. The ends of the pair of screws 15 are located in the vicinity of the inlet 21 of the die head 20 in the resin flow path of the flange 14. Further, the resin flow path of the die head 20 has a reduced portion 22 whose cross-sectional area decreases as it proceeds from the inlet 21 into the die head 20. The reduced portion 22 is adjacent to the narrowed portion 23 having the smallest cross-sectional area in the resin flow path. The resin flow path is kept constant in the narrow portion 23. Further, the narrow portion 23 is adjacent to the widened portion 24 where the cross-sectional area of the resin flow path suddenly increases on the side opposite to the reduction portion 22 side in the resin flow path. The portion of the widened portion 24 where the resin flow path is most expanded is the outlet of the die head 20, and the die plate 30 is fixed to the outlet.

  The die plate 30 includes a rectifying plate 31, and die nozzles 32 including 20 or more and 60 or less parallel through holes are formed in parallel to each other at a predetermined interval so as to surround the rectifying plate 31. By fixing the die plate 30 to the outlet of the die head 20, the rectifying plate 31 that is a part of the die plate 30 is inserted into the widened portion 24 from the outlet. In this state, the rectifying plate 31 is fixed so as to maintain a constant distance from the inner wall surface of the die head 20 that forms the widened portion 24 in substantially the entire widened portion 24. A space between the inner wall surface of the die head 20 and the current plate 31 in the widened portion 24 is a resin flow path in the widened portion 24, and the resin flow path in the widened portion 24 is connected to the die nozzle 32 adjacent to the die nozzle 32. By fixing the rectifying plate 31 in this manner, the widened portion 24 has a structure in which the resin flow path expands in the direction in which the die nozzles 32 are arranged as the resin flows in the direction in which the resin flows. In addition, the widened portion 24 suppresses the spread of the resin flow path before the die nozzle 32. And the side opposite to the rectifying plate 31 side of the die nozzle 32 is a discharge port for discharging resin.

  FIG. 4 is a plan view of the die plate 30 from the discharge port side. This direction in plan view is a direction in which a plane perpendicular to the longitudinal direction of the die nozzle 32 is seen in plan view. As shown in FIG. 4, a part of the die nozzle 32 of the present embodiment is arranged so that the discharge ports are arranged in two straight lines, and the other part of the die nozzle 32 has the above-mentioned discharge ports having two straight lines. They are arranged in a semicircular shape. Thus, the die nozzle 32 is generally arranged in the track shape of an athletic stadium. Further, when the die plate 30 is viewed in plan from the discharge port side, the rectifying plate 31 is formed so as to be surrounded by the discharge ports of the die nozzles 32 arranged in a track shape as described above. Has a shape in which the end in the width direction of a portion having a certain thickness is circular. Further, the inner wall surface of the die head 20 that forms a portion of the widened portion 24 that contacts the die plate 30 has a track shape surrounding the die nozzle 32. Thus, in this embodiment, since the die nozzle 32 is arranged in a track shape, the widened portion 24 expands in a track shape as it proceeds in the resin flow direction.

  Further, when the distance between the inner wall surface of the die head 20 in the widened portion 24 and the rectifying plate 31 is the height of the resin flow path in the widened portion, the height is substantially constant. The diameter of the die nozzle 32 is made smaller than the height of the resin flow path in the widened portion 24 and is constant over the entire longitudinal direction of the die nozzle 32.

  Next, the resin pellet manufacturing method by the resin pellet manufacturing apparatus will be described.

  From the hopper 12 of the extruder 1, resin to be pelletized is charged. Examples of this resin include resins mainly composed of engineering plastics such as polycarbonate resin, polybutylene terephthalate resin, polyphenylene ether resin, polyacetal resin, polyamide MXD6 resin (polyamide obtained from metaxylylenediamine and adipic acid). Can do.

  The resin is preferably engineering plastics to which a stabilizer is added, and particularly preferably engineering plastics to which an epoxy stabilizer is added. Examples of the epoxy stabilizer include bisphenol A glycidyl ether, epoxidized polybutadiene, epoxidized fatty acid, epoxyhexahydrophthalic acid, epoxidized soybean oil, and epoxidized linseed oil.

  Further, this resin is preferably engineering plastics to which a flame retardant is added, and particularly preferably engineering plastics to which an epoxy flame retardant is added. Examples of the epoxy flame retardant include brominated epoxy oligomers and brominated epoxy polymers.

  When the resin contains an epoxy group as described above, it is preferable to contain an epoxy group of 0.1 mol / kg or less. When the resin contains an epoxy group of 0.1 mol / kg or less, it is possible to further suppress burning. In addition, resin can improve stability and a flame retardance more because a resin contains 0.01 mol / kg or more of epoxy groups.

  The resin is preferably an engineering plastic to which a carboxylic acid anhydride is added, and the carboxylic acid anhydride can function as a compatibilizing agent. Examples of carboxylic acid anhydrides include acetic anhydride, propionic anhydride, succinic anhydride, maleic anhydride, and phthalic anhydride. In this case, the resin preferably contains 0.1 mol / kg or less of carboxylic acid anhydride. When the resin contains 0.1 mol / kg or less of carboxylic acid anhydride, it is possible to further suppress burning. In addition, the compatibility of resin improves more because resin contains 0.01 mol / kg or more of carboxylic acid anhydride.

  In addition to this resin, other engineering plastics, polystyrene, AS resin, ABS resin, HIPS resin, polypropylene and other additives, release agents, additives, talc, mica, kaolin, carbon, graphite, wollast Knight, fillers such as titanium oxide, reinforcing fibers such as glass fiber and carbon fiber, phosphorus flame retardant, silicon flame retardant, antimony oxide, alkali metal salt, brominated polycarbonate, brominated polystyrene, polypentabromobenzyl acrylate A flame retardant such as may be added.

  The charged resin is melted and pushed while being kneaded by the pair of screws 15, and flows from the extruder 1 into the resin flow path from the inlet 21 of the extrusion die 2. In addition, when the other opening which adds an additive and a filler is formed in the cylinder 11, the said stabilizer, a flame retardant, a filler, etc. may be injected from the said other opening.

  The molten resin flowing from the inflow port 21 flows from the reduced portion 22 to the narrowed portion 23 and reaches the widened portion 24. Then, the resin flows along the widened portion 24, flows into the die nozzle 32, and is discharged from the discharge port of the die nozzle 32. The protruding resin is cooled and cut into a predetermined length to obtain resin pellets.

In this case, the widened portion 24 of the resin flow path to the front of die nozzles 32, i.e. the volume of the entrance of the widening section 24 to the entrance of the die nozzle 32 and Vcm ^3, the resin per unit time to be discharged from the discharge port of the die nozzle 32 When the amount is Qcm ³ / sec, the following formula (1) is satisfied.
1.0Q ≦ V ≦ 3.0Q (1)

  That is, the raw material is supplied to the hopper so that the resin can be discharged so as to satisfy the formula (1). Formula (1) indicates that the time during which the resin stays in the widened portion 24 is 1 second or more and 3 seconds or less. It has been found that satisfying this equation can suppress the burning of the resin in the widened portion 24 and the die nozzle 32.

  The reason is considered as follows. In the extrusion molding die 2 used in the resin pellet manufacturing apparatus of this embodiment, the number of die nozzles 32 is 20 to 60. In the extrusion molding die 2 of such a scale, when the time that the resin stays in the widened portion 24 is 3 seconds or more, the epoxy-based additive contained in the resin reacts with the metal constituting the extrusion molding die 2. Tend to. Therefore, the occurrence of the burn can be reduced by setting the time for the resin to remain in the resin flow path within 3 seconds. On the other hand, in the extrusion die 2 having a scale having 20 to 60 die nozzles 32, the depth of the widened portion 24 in the resin flow direction is correspondingly large. Therefore, in the extrusion die 2 as described above, the time that the resin stays in the widened portion 24 where the resin is easily burnt is shorter than 1 second, which means that the resin flows at a high speed. For this reason, it is considered that the resin generates heat due to the shear resistance of the resin, and this heat raises the temperature of the extrusion die and causes burning. Therefore, the occurrence of burning can be reduced when the resin stays in the widened portion 24 for 1 second or longer.

Furthermore, the extrusion molding die 2 satisfies the following formula (2) when the total sum of the intervals (distances between the centers of the discharge ports) of the die nozzles 32 is Lcm.
2 cm ² ≦ V / L ≦ 6 cm ² (2)

  As described above, the height of the resin flow path in the widened portion 24 is substantially constant. Therefore, V / L in the above formula (2) represents the product of the channel height in the widened portion 24 and the channel length, which is the length of the resin flowing in the widened portion 24. In the extrusion die 2 having a scale of 20 to 60 die nozzles as in this embodiment, the flow path length is correspondingly long. Therefore, when V / L satisfies the above formula (2), the flow velocity of the resin in the widened portion 24 can be set to a more appropriate range, and the burn in the widened portion can be further suppressed.

  As described above, according to the resin pellet manufacturing method and the resin pellet manufacturing apparatus of this embodiment, the discharge of the die nozzle 32 from the widened portion 24 of the extrusion die 2 having a scale of 20 to 60 protrusions. Burning of the resin is suppressed up to the outlet, and thus burnt pellets can be reduced.

  As mentioned above, although this invention was demonstrated to the example for embodiment, this invention is not limited to these.

  For example, in the above embodiment, the die nozzle 32 is arranged in a track shape when a plane perpendicular to the longitudinal direction of the die nozzle 32 is viewed in plan view. However, the present invention is not limited to this, and the die nozzles 32 may be arranged in a circular shape or in a linear shape. When the die nozzle 32 is arranged in a circular shape, the rectifying plate 31 has a circular shape perpendicular to the longitudinal direction. FIG. 5 is a plan view of the die plate 30 when the die nozzles 32 are arranged in a straight line from the discharge port side. When the die nozzles 32 are linearly arranged in a line, as shown in FIG. 5, the rectifying plate 31 is linearly inserted into the space in the die head 20 that becomes the widened portion shown in FIG. The rectifying plate 31 has a resin flow path having a shape that becomes the widened portion 24, and the resin flow path has a large height at the end in the width direction. In any case, the flow path height of the widened portion 24 is substantially constant in the resin flow direction.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Example 1>
Resin pellets were produced by a resin pellet production apparatus in which an extrusion molding die was installed in the extruder.

The extrusion molding die had the following specifications in the extrusion molding die shown in FIGS. The narrow part of the resin flow path was circular with a diameter of 45 mm. The widened part has a structure in which the width suddenly widens from the narrow part to the coat hanger, and the widened part is inserted into the widened part by a rectifying plate whose cross-sectional shape is flat and whose both ends in the width direction are semicircular. The cross-sectional shape perpendicular to the resin flow was a track shape having a resin flow path height of 7.5 mm. The die nozzles formed on the die plate are arranged so that the discharge ports are arranged in a straight line and the ends are arranged in a semicircular shape, and the number thereof is 41. The total length L of lines connecting adjacent die nozzles was 98 cm. In the extrusion molding die, the volume V of the space from the start portion of the widened portion to the front of the die nozzle was 420 cm ³ . Therefore, V / L is 4.29 cm ² . This extrusion die was designated as Die A.

  As the extruder, TEX65αII manufactured by Nippon Steel Works was used. The screw used in the extruder was a combination of kneading disks. R disk (5 paddles, 65 mm length), N disk (5 paddles, 65 mm length), L disk (5 paddles, 65 mm length) causing reverse flow in series From the downstream, they were arranged in the order of RRNNL. In addition, a vacuum vent was disposed downstream of the screw kneading position, and a vacuum was drawn to remove low-boiling components.

The resin used for the resin pellets is 99.5 parts by weight of polybutylene terephthalate (trade name 5020C, intrinsic viscosity 1.2 dl / g, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) and bisphenol A glycidyl ether (trade name EP, manufactured by ADEKA Corporation). -17, epoxy equivalent 7 mol / kg) 0.5 parts by weight of a mixture was used. The specific gravity at the time of melting was 1.1 g / cm ³ .

  And the mixture of the said resin was fed to the hopper of the extruder at 1000 kg / hour. And the preset temperature of the cylinder of a resin pellet manufacturing apparatus was 280 degreeC, and the preset temperature of the die head was 320 degreeC. The screw rotation speed was 400 rpm.

  The temperature of the strand coming out of the die nozzle was measured and found to be 328 ° C. The strand was cooled in a water bath and cut with a pelletizer to obtain resin pellets.

This operation was performed for 2 hours to obtain 2000 kg of resin pellets. In this case, the discharge amount Q per second is 252 cm ³ / second. Therefore, V / Q is 1.67 seconds. Thereafter, the burned pellets were sorted from the obtained resin pellets using a foreign matter sorter (Platon II manufactured by Kubota Corporation). In Plato II, two cameras with 5150 pixels were used, the resolution was 0.04 mm, and the threshold was 80%.

  The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 2>
The resin used for the resin pellets is 80 parts by weight of polybutylene terephthalate (trade name 5020C manufactured by Mitsubishi Engineering Plastics Co., Ltd.), brominated epoxy flame retardant (trade name CXB-2000H manufactured by WOOJIN COPOLYMER, epoxy equivalent 0.2 mol / kg). Example 1 was repeated except that the mixture was 20 parts by weight. The specific gravity at the time of melting was 1.1 g / cm ³ .

  Using this material, resin pellets were obtained in the same manner as in Example 1, and burnt pellets were selected. The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 3>
The resin used for the resin pellet is a mixture of 99.5 parts by weight of polycarbonate (trade name S3000F, molecular weight 21500, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) and 0.5 part by weight of bisphenol A glycidyl ether (ADEKA trade name EP-17, Ltd.). Example 1 was the same as in Example 1. The specific gravity at the time of melting was 1.1 g / m ³ .

  Using this material, resin pellets were obtained in the same manner as in Example 1, and burnt pellets were selected. The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 4>
The resin used for the resin pellet is a mixture of 99.0 parts by weight of polybutylene terephthalate (Mitsubishi Engineering Plastics Co., Ltd. trade name 5020C) and 1.0 part by weight of bisphenol A glycidyl ether (ADEKA trade name EP-17) The procedure was the same as in Example 1 except that the above was done. The epoxy group content of this resin was 0.07 mol / kg.

  Using this material, resin pellets were obtained in the same manner as in Example 1, and burnt pellets were selected. The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 5>
Resin pellets were obtained in the same manner as in Example 1 except that the screw rotation speed was 320 rpm and the discharge amount from the die nozzle was 800 kg / hour. In this case, the discharge amount Q is 202 cm ³ / second, and V / Q is 2.08 seconds.

  The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 6>
Resin pellets were obtained in the same manner as in Example 1 except that the screw rotation speed was 240 rpm and the discharge rate from the die nozzle was 600 kg / hour. In this case, the discharge amount Q is 151 cm ³ / second, and V / Q is 2.78 seconds.

  The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 7>
Resin pellets were obtained in the same manner as in Example 1 except that the screw rotation speed was 480 rpm and the discharge rate from the die nozzle was 1200 kg / hour. In this case, the discharge amount Q is 303 cm ³ / second, and V / Q is 1.39 seconds.

  The above specifications and the number of burnt pellets are shown in Table 1. As apparent from Table 1, the number of burnt pellets was 2, and when the die head was confirmed, it was confirmed that brown burnt had occurred at the corner portion of the widened portion inside the die.

<Example 8>
The resin used for the resin pellet is 99.8 parts by weight of polybutylene terephthalate (trade name 5020C, intrinsic viscosity 1.2 dl / g, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) and bisphenol A glycidyl ether (trade name EP-, manufactured by ADEKA Corporation). 17 and epoxy equivalent 7 mol / kg) Resin pellets were obtained in the same manner as in Example 1 except that the mixture was 0.2 parts by weight.

  The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Example 9>
The resin used for the resin pellets was 98.5 parts by weight of polybutylene terephthalate (trade name 5020C, intrinsic viscosity 1.2 dl / g, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) and bisphenol A glycidyl ether (trade name EP-, manufactured by ADEKA Corporation). 17 and epoxy equivalent 7 mol / kg) Resin pellets were obtained in the same manner as in Example 1 except that the mixture was 1.5 parts by weight.

The above specifications and the number of burnt pellets are shown in Table 1. As apparent from Table 1, the number of burnt pellets was 3, and when the die head was confirmed, it was confirmed that brown burnt occurred at the corner portion of the widened portion inside the die.
<Example 10>
The shape of the die head and die plate was changed to that of Example 1. Specifically, the shapes of the current plate and the die plate were changed so that the height of the resin flow path at the widened portion was 3.5 mm. Further, the number of die nozzles was 59, and the total length L of lines connecting adjacent die nozzles was 155 cm. As a result, the volume V of the space from the widened portion of this die head to the front of the die nozzle was 300 cm ³ . Therefore, V / L is 1.94 cm ² . This extrusion die was designated as a die D. Otherwise, resin pellets were obtained in the same manner as in Example 1. Since the discharge amount Q per second is 252 cm ³ / second, V / Q is 1.19 seconds.

The above specifications and the number of burnt pellets are shown in Table 1. As apparent from Table 1, the number of burnt pellets was 2, and when the die head was confirmed, it was confirmed that brown burnt had occurred at the corner portion of the widened portion inside the die.
<Example 11>
The shape of the die head and die plate was changed to that of Example 1. Specifically, the shapes of the current plate and the die plate were changed so that the height of the resin flow path at the widened portion was 6.0 mm. Further, the number of die nozzles was 49, and the total length L of lines connecting adjacent die nozzles was 120 cm. As a result, the volume V of the space from the widened portion of this die head to the front of the die nozzle was 300 cm ³ . Therefore, V / L is 2.50 cm ² . This extrusion die was designated as die E. Otherwise, resin pellets were obtained in the same manner as in Example 1. Since the discharge amount Q per second is 252 cm ³ / second, V / Q is 1.19 seconds.

The above specifications and the number of burnt pellets are shown in Table 1. As is apparent from Table 1, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.
<Example 12>
The shape of the die head and die plate was changed to that of Example 1. Specifically, the shapes of the current plate and the die plate were changed so that the height of the resin flow path at the widened portion was 8.3 mm. The number of die nozzles was 29, and the total length L of the lines connecting the die nozzles adjacent to each other was 76 cm. As a result, the space from the widened portion of this die head to the front of the die nozzle was 420 cm ³ . Therefore, V / L is 5.53 cm ² . This extrusion die was designated as die F. Otherwise, resin pellets were obtained in the same manner as in Example 1. Since the discharge amount Q per second is 252 cm ³ / second, V / Q is 1.67 seconds.

<Example 13>
The shape of the die head and die plate was changed to that of Example 1. Specifically, the shapes of the current plate and the die plate were changed so that the height of the resin flow path at the widened portion was 10.0 mm. Further, the number of die nozzles was 23, and the total length L of lines connecting adjacent die nozzles was 63 cm. As a result, the space from the widened portion of the die head to the discharge port of the die nozzle was 420 cm ³ . Therefore, V / L is 6.67 cm ² . This extrusion die was designated as die G. Otherwise, resin pellets were obtained in the same manner as in Example 1. Since the discharge amount Q per second is 252 cm ³ / second, V / Q is 1.67 seconds.

  The above specifications and the number of burnt pellets are shown in Table 1. As apparent from Table 1, the number of burnt pellets was 2, and when the die head was confirmed, it was confirmed that brown burnt had occurred at the corner portion of the widened portion inside the die.

Table 1 is shown below.

<Comparative Example 1>
The shapes of the die head and die plate were changed from those in Example 1. Specifically, the shapes of the current plate and the die plate were changed so that the height of the resin flow path at the widened portion was 15 mm. Further, the number of die nozzles was 41, and the total length L of lines connecting adjacent die nozzles was 93 cm. As a result, the volume V of the space from the widened portion of the die head to the discharge port of the die nozzle was 800 cm ³ . Therefore, V / L is 8.60 cm ² . This extrusion die was designated as die B. Otherwise, resin pellets were obtained in the same manner as in Example 1. Since the discharge amount Q per second is 252 cm ³ / second, V / Q is 3.17 seconds.

  The above specifications and the number of burnt pellets are shown in Table 2. As is apparent from Table 2, the number of burnt pellets was 8, and when the die head was confirmed, it was confirmed that black burn occurred at the corner portion of the widened portion inside the die.

<Comparative example 2>
The resin used for the resin pellets was a mixture of 80 parts by weight of polybutylene terephthalate (Mitsubishi Engineering Plastics, trade name 5020C) and 20 parts by weight of brominated epoxy flame retardant (trade name CXB-2000H made by WOOJIN COPOLYMER). Obtained a resin pellet as in Comparative Example 1.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 2, the number of burnt pellets was 12.

<Comparative Example 3>
The resin used for the resin pellets was a mixture of 99.5 parts by weight of polycarbonate (manufactured by Mitsubishi Engineering Plastics, product name S3000F) and 0.5 parts by weight of bisphenol A glycidyl ether (manufactured by ADEKA, product name EP-17). Except this, resin pellets were obtained in the same manner as in Comparative Example 1.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 2, the number of burnt pellets was 7.

<Comparative Example 4>
The shape of the die head and die plate was changed to that of Example 1. Specifically, the shapes of the current plate and the die plate were changed so that the height of the resin flow path at the widened portion was 4 mm. The number of die nozzles was 41, and the total length L of lines connecting adjacent die nozzles was 99 cm. As a result, the volume V of the space from the widened portion of the die head to the discharge port of the die nozzle was 225 cm ³ . Therefore, V / L is 2.27 cm ² . This extrusion die was designated as die C. Otherwise, resin pellets were obtained in the same manner as in Example 1. Since the discharge amount Q per second is 252 cm ³ / second, V / Q is 0.89 seconds.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 2, the number of burnt pellets was 6.

<Comparative Example 5>
The resin used for the resin pellets was a mixture of 80 parts by weight of polybutylene terephthalate (Mitsubishi Engineering Plastics, trade name 5020C) and 20 parts by weight of brominated epoxy flame retardant (trade name CXB-2000H made by WOOJIN COPOLYMER). Obtained a resin pellet as in Comparative Example 4.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 2, the number of burnt pellets was 5.

<Comparative Example 6>
The resin used for the resin pellets was a mixture of 99.5 parts by weight of polycarbonate (manufactured by Mitsubishi Engineering Plastics, trade name S3000F) and 0.5 parts by weight of bisphenol A glycidyl ether (ADEKA, trade name EP-17). Except that, resin pellets were obtained in the same manner as in Comparative Example 4.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 2, the number of burnt pellets was 6.

<Comparative Example 7>
Using the same die A as in Example 1, the raw material feeder was adjusted, and the resin mixture was fed to the hopper of the extruder at 520 kg / hour. In this case, the discharge amount Q is 131 cm ³ / second, and V / Q is 3.21 seconds. Except this, resin pellets were obtained in the same manner as in Example 1.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 2, the number of burnt pellets was 5.

Table 2 is shown below.

<Example 14>
The resin used for the resin pellets is 50 parts by weight of polyphenylene ether (Mitsubishi Engineering Plastics, trade name PX100L), 49.5 parts by weight of polyamide (Mitsubishi Chemical, trade name 101NC-10), maleic anhydride (Nippon Shokubai Co., Ltd.) Product) Resin pellets were obtained in the same manner as in Example 1 except that the mixture was 0.5 parts by weight.

  The above specifications and the number of burnt pellets are shown in Table 3. As apparent from Table 3, the number of burnt pellets was 0, and when the die head was confirmed, no resin burn was confirmed.

<Comparative Example 8>
Resin pellets were obtained in the same manner as in Example 14 except that the die B was used.

  The above specifications and the number of burnt pellets are shown in Table 3. As apparent from Table 3, the number of burnt pellets was 5.

<Comparative Example 9>
Resin pellets were obtained in the same manner as in Example 14 except that the dice C was used.

  The above specifications and the number of burnt pellets are shown in Table 2. As apparent from Table 3, the number of burnt pellets was 4.

Table 3 is shown below.

From the above, when the above formula (1) is established between the volume Vcm ³ from the widened portion to the discharge port of the die nozzle and the amount Qcm ³ / sec per unit time that the resin is discharged from the die nozzle, The number was 3 or less, and according to the present invention, it was confirmed that burnt pellets can be reduced.

Further, from Examples 1 to 7, when the above formula (2) is established between the volume Vcm ³ and the distance between the centers of the discharge ports adjacent to each other (distance between die nozzles) Lcm, The number became 0, and it was confirmed that burnt pellets could be further reduced. Therefore, when this condition is satisfied, it has been found that the burn in the widened portion can be further suppressed.

  As described above, according to the present invention, a resin pellet manufacturing method and a resin pellet manufacturing apparatus capable of reducing burnt pellets are provided and can be used in the field of resin molding.

DESCRIPTION OF SYMBOLS 1 ... Extruder 2 ... Extrusion die 11 ... Cylinder 12 ... Hopper 15 ... Screw 20 ... Die head 21 ... Inlet 22 ... Reduction part 23 ... Narrow part 24 ... Widened part 30 ... Die plate 31 ... Rectifying plate 32 ... Die nozzle

Claims (8)

A resin pellet manufacturing method for extruding a resin from an extrusion die,
The extrusion die includes an inflow port through which molten resin flows, 20 to 60 die nozzles from which the resin is discharged and disposed at a predetermined interval, and the inflow between the inflow port and the die nozzle. A widened portion that is formed at a position adjacent to the die nozzle and expands in the direction in which the die nozzles are arranged as the resin flows in the direction of flow, and that prevents the resin channel from spreading before the die nozzle. ,
If the volume of the entrance of the widened portion to the entrance of the die nozzle and Vcm ^3, wherein the resin is a Qcm 3 ^/ sec the amount per unit for discharging time from the die nozzle,
1.0Q ≦ V ≦ 3.0Q
The resin pellet manufacturing method characterized by satisfy | filling. When the total distance between the centers of the discharge ports of the die nozzles adjacent to each other is Lcm,
2 cm ² ≦ V / L ≦ 6 cm ²
The resin pellet manufacturing method according to claim 1, wherein: The resin pellet manufacturing method according to claim 1, wherein the resin is engineering plastics. 4. The resin pellet manufacturing method according to claim 3, wherein the engineering plastic is a polybutylene terephthalate resin. The method for producing resin pellets according to claim 3 or 4, wherein the resin contains an epoxy group of 0.1 mol / kg or less. 6. The resin pellet manufacturing method according to claim 3, wherein the resin contains 0.1 mol / kg or less of carboxylic acid anhydride. A resin pellet manufacturing apparatus for extruding a resin from an extrusion die,
The extrusion die includes an inflow port through which molten resin flows, 20 to 60 die nozzles from which the resin is discharged and disposed at a predetermined interval, and the inflow between the inflow port and the die nozzle. A widened portion that is formed at a position adjacent to the die nozzle and has a widened resin flow path in a direction in which the die nozzle is arranged as it proceeds in the direction in which the resin flows.
If the volume of the entrance of the widened portion to the entrance of the die nozzle and Vcm ^3, wherein the resin is a Qcm 3 ^/ sec the amount per unit for discharging time from the die nozzle,
1.0Q ≦ V ≦ 3.0Q
The resin pellet manufacturing apparatus characterized by satisfy | filling. When the total distance between the centers of the discharge ports of the die nozzles adjacent to each other is Lcm,
2 cm ² ≦ V / L ≦ 6 cm ²
The resin pellet manufacturing apparatus according to claim 7, wherein:

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