JP5287073B2 - Sorting method of resin pellets - Google Patents

Description

  The present invention relates to a method for sorting resin pellets having a specific shape, and more particularly to a method for separating the shape of thermoplastic resin pellets cut after being discharged from an extruder using a vibrating sieve.

  When the thermoplastic resin and other auxiliary materials are pelletized after being melted, kneaded and discharged by an extruder, the pellet is cut and pelletized in a molten state or a solidified state. In other words, abnormally shaped pellets such as long, thick, and continuous pellets (in which a plurality of pellets are fused) may be mixed.

  In many cases, the pelletized thermoplastic resin is measured and melted in an injection molding machine or the like to be molded into a desired shape. If abnormally shaped pellets are mixed at this time, adverse effects will be exerted on weighing and melting. Therefore, it is necessary to sort non-defective pellets and abnormally shaped pellets.

  In many cases, a vibrating sieve device is used as a conventional technique for sorting out abnormally shaped pellets. As a vibrating screen device for sorting out such particles, horizontal vibrating type, horizontal rotating type, inclined type are used. As a vibration source, a mechanical type, a spring type, an unbalancer rotation type, a vibration motor, an electromagnetic type, and the like are known.

For example, in the selection of a mini-pellet called a masterbatch made of a thermoplastic resin and a pigment in Patent Document 1, the size of the sieve face, the arrangement of the holes, the vibration angle of the pellet having a larger diameter or height We propose a method for efficient sorting by optimization. However, when determining the size of the pores on the sieve surface relative to the size of the pellets, the method of determining the size of the pores on the sieve surface with respect to the larger diameter or height is insufficient to select abnormally shaped pellets. It was.
JP 2002-233824 A

  An object of the present invention is to provide a resin pellet sorting method capable of improving the removal rate of abnormally shaped pellets in the prior art as described above.

The present inventors diligently studied to solve these problems, and found out a method capable of improving the removal rate of abnormally shaped pellets, resulting in the present invention. That is, the resin pellet sorting method of the present invention is as follows.
1. In the method of sorting cylindrical resin pellets on a vibrating screen on a vibrating sieve, when the diameter of the cylindrical resin pellet is D and the length is H, the diagonal length L formed by D and H was less than 5mm than 4 mm, a plurality have a 1.05 to 1.15 times the hole diameter d of the hole with respect to L, and the pitch P of the open width direction of the holes in the sieve surface, 1.8 to 2 A method for sorting resin pellets, characterized by sorting on a sieve surface of 0.0d .
2 . 1 Symbol mounting method of selecting the resin pellets, wherein the frequency of the sifter is 2000～4000Vpm.
3 . 3. The method for sorting resin pellets according to 1 or 2, wherein the sieve has an amplitude of 0.3 to 0.75 mm.

  If the resin pellets are sorted by the resin pellet sorting method of the present invention, the removal rate of abnormally shaped pellets can be improved. In particular, the removal rate of abnormally shaped pellets that deviate from the standard only in the height direction of the pellets can be improved.

  Hereinafter, embodiments of the resin pellet sorting method of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view of a vibration sieve device according to an embodiment of the present invention, which includes a vibration drive unit 1 and an adjustment unit 2 for adjusting the frequency and amplitude thereof. The cut pellets including the abnormally shaped pellets are input from the input unit 3, and the abnormally shaped pellets pass over the upper sieve surface 4 and are discharged from the abnormally shaped pellet discharge port 8. The non-defective pellets pass through the holes on the upper sieve surface 4, pass over the lower sieve surface 5, and are discharged from the non-defective pellet discharge port 7. Powdered material such as debris adhering to the pellets passes through the lower sieve surface 5 and is discharged from the powder discharge port 6.

  When L is 4 mm to 5 mm as shown in FIG. 2, the pore diameter d of the sieve surface needs to be 1.05 to 1.15 times that of L. If it is smaller than 1.05 times, the pellets in the holes, that is, the processing ability may be reduced. If it is 1.15 times or more, the abnormally shaped pellets pass through the holes on the sieve surface and cannot be removed. In particular, triple-length pellets, quadruple-length pellets, and the like that are out of specification only in the height direction of the pellet can be removed. The holes can be efficiently processed if the shape connecting the centers of the three adjacent holes forms an apex of an equilateral triangle.

  Further, the frequency is preferably 2000 to 4000 vpm, and if it is less than 2000 vpm, vibrations are not sufficiently transmitted to the pellets and the processing ability is lowered, which is not preferable. Moreover, when larger than 4000 vpm, since a pellet jumps up on a sieve surface and processing capacity will fall, it is unpreferable.

  The amplitude is the amplitude of the drive unit, and is preferably 0.3 to 0.75 mm. If the amplitude is smaller than 0.3 mm, the pellets are not sufficiently separated, which is not preferable because the processing capacity is lowered. Moreover, when larger than 0.75 mm, since a pellet jumps up a sieve surface and processing capacity will fall, it is unpreferable.

  FIG. 3 is a view of the sieving surface as viewed from the direction perpendicular to the sieving surface, and the pitch P of the holes in the width direction on the sieving surface is preferably 1.8 to 2.0d. If it is smaller than 1.8d, in particular, triple pellets that are out of specification only in the height direction of the pellets, quadruple pellets, etc. will pass through the holes on the sieve surface by their own weight, so they cannot be removed efficiently. Absent. Moreover, when larger than 2.0d, since a big sieve is needed in order to process a pellet, it is unpreferable. Here, the pitch P refers to the length connecting the centers of the holes adjacent in the width direction.

  The vibration source used in the present invention is generally an electromagnetic type, but any vibration source can be used as long as it can generate the vibration frequency and amplitude in the above-mentioned range.

  Further, the angle of the sieve surface is preferably 10 ° to 30 ° with respect to the horizontal plane, and if it is less than 10 °, the pellets do not advance on the sieve surface and the processing capacity is lowered, which is not preferable. On the other hand, if it is larger than 30 °, abnormally shaped pellets are likely to rise and cannot be removed, which is not preferable.

  Next, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples.

  Nylon resin pellets were selected using Isuzu Chemical Industries VS-4 and Isuzu Chemical Industries IS-7 in this example, and Isuzu Chemical Machine VS-4 in Comparative Examples. In this example and a comparative example, a certain amount of abnormally shaped pellets were mixed in a certain amount of non-defective pellets and selected with a vibrating sieve, and the removal rate of abnormally shaped pellets was evaluated. The vibration sieving machine, pellets used, sieving surface, and evaluation method will be described below.

(1) Vibrating sieve The vibrating sieve used in the examples and comparative examples is as follows. In Examples 1 and 3 and Comparative Example 1, VS-4 was used, and in Example 2, IS-7 was used.
・ VS-4 (Isuzu Chemical Co., Ltd.)
Vibration source: Vibration motor
Frequency: 1800 vpm
Amplitude: 1.2 mm
Sieve area: Width 350mm x Length 990mm
・ IS-7 (Isuzu Chemical Co., Ltd.)
Vibration source: Vibration motor
Frequency: 3000 vpm
Amplitude: 0.6 mm
Sieve area: width 650 mm x length 1160 mm

(2) Pellet characteristics The characteristics of the pellets used in the examples and comparative examples are as follows.
Material: Nylon pellets (Toray Industries, Inc. Amilan CM3001G30B1)
Shape: Diameter D = 3.1-3.2mm
Length H = 3.5-3.7mm
Diagonal length L = 4.8-4.9 mm
Amount: 2kg

(3) Sieve surface The sieving surfaces used in the examples and comparative examples are as follows. As the arrangement of the holes on the sieve surface used in the examples and comparative examples, those in which three adjacent holes are arranged so as to form the vertices of an equilateral triangle were used.
Examples 1 and 2: Hole diameter φ5.5 mm (d = 1.12 to 1.15 L)
Pitch 10mm (P = 1.82d)
Example 3: hole diameter φ5.5 mm (d = 1.12 to 1.15 L)
Pitch 9mm (P = 1.64d)
Comparative Example 1: Hole diameter φ6 mm (d = 1.22 to 1.25 L)
Pitch 10 mm (P = 1.67d).

(4) Evaluation method The evaluation in this Example and the comparative example evaluated the non-defective pellet by mixing the abnormally shaped pellet and the number of removed pellets with respect to the number of the mixed pellets. The abnormally shaped pellets were mixed with 40 pieces of 3 times longer pellets that were 3 times longer than the length H of good quality pellets and 4 times longer 4 times longer pellets.

  The results of Examples and Comparative Examples are shown in Table 1. Compared with the comparative example, it can be seen that the removal rate of the abnormally shaped pellets in the example is improved.

The figure seen from the horizontal direction in the apparatus schematic of a vibration sieve. The schematic diagram of a pellet. The figure which looked at the sieving surface from the perpendicular | vertical direction with respect to the sieving surface.

Explanation of symbols

1: Vibration drive unit 2: Adjustment unit 3: Input unit 4: Upper screen surface 5: Lower screen surface 6: Powder discharge port 7: Non-defective pellet discharge port 8: Abnormally shaped pellet discharge port

Claims (3)

In the method of sorting cylindrical resin pellets on a vibrating screen on a vibrating sieve, when the diameter of the cylindrical resin pellet is D and the length is H, the diagonal length L formed by D and H was less than 5mm than 4 mm, a plurality have a 1.05 to 1.15 times the hole diameter d of the hole with respect to L, and the pitch P of the open width direction of the holes in the sieve surface, 1.8 to 2 A method for sorting resin pellets, characterized by sorting on a sieve surface of 0.0d . Selection method of claim 1 Symbol placing resin pellets, wherein the frequency of the sifter is 2000～4000Vpm. 3. The method for sorting resin pellets according to claim 1, wherein the sieve has an amplitude of 0.3 to 0.75 mm.

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