JP2003200422A - Method for manufacturing resin pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing resin pellets in which rod-like bodies can be extrusion-molded without increasing mechanical loading of an extrusion molding machine and pellets can be formed without cutting the rod- like bodies and furthermore, the pellets are prevented from being stuck together and accumulated on the underside of a blade and the like of a cutting machine and production efficiency and the quality of the pellets are improved. <P>SOLUTION: The rod-like resin 40 is extruded from through-holes 14 of a die plate 13 of the extrusion molding machine and water is sprayed into misty condition onto the extruded rod-like resin from a water mixing air nozzle 15 and it is cut into a specified dimension under a water atmosphere by means of a rotating blade 22 of a cutting machine 20 to form the pellets 60 and the formed pellets 60 are made to fall down into a running water to cool them and the water is separated from the cooled pellets 60 by means of a centrifugal separation type dehydrator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a manufacturing method for manufacturing pellets of polyolefin resin.

[0002]

2. Description of the Related Art Conventionally, in order to easily handle a thermoplastic molding resin, an antioxidant, a colorant,
Various compounding agents such as stabilizers and lubricants are kneaded and molded to produce granular pellets.

Such pellets are manufactured by extruding a heated resin into a rod-shaped body having a diameter of several mm by an extruder and a die plate, and cutting it into a length of several mm by a breaking machine. However, a polyolefin resin such as polyethylene has a wide softening temperature range and the degree of decrease in melt viscosity due to a decrease in temperature is small, so that the pellets are fused together during the cooling process. For this reason, the resin may be extruded as a rod-shaped body in water and then ruptured to obtain pellets,
It is generally practiced to extrude a resin in the form of a rod and then break it in water to obtain pellets, or to break the resin extruded in the form of a rod in the air to make pellets and then cool with water.

[0004]

However, in the conventional method of extruding a resin as a rod-shaped body in water and then breaking it to obtain pellets, the die plate is water-cooled, so that the viscosity of the extruded resin increases. However, there is a problem that the mechanical load of the extrusion molding machine such as increasing the extrusion pressure of the extrusion molding machine is increased, and it is difficult to produce a rod-shaped body with high efficiency. In addition, the method of extruding the resin as a rod and breaking it in water to obtain pellets is because the resin before water cooling is a rod and the viscosity is low, the rod is easy to cut, and it is necessary to monitor the rod. There is a problem that is. Furthermore, the method of breaking the resin extruded as a rod in the air into pellets and water cooling is because when the continuous extrusion molding is performed at high speed, the die plate and the breaking machine become high temperature due to self-heating of the resin. However, there is a problem that the pellets are deposited on the back of the blade of the breaking machine and the like, and the pellets become defective due to dropping.

Therefore, it is an object of the present invention to extrude a rod without increasing the mechanical load of the extruder, to produce pellets without cutting the rod, and to use a blade of a breaking machine. It is an object of the present invention to provide a method for producing resin pellets, which can prevent mutual deposition of pellets on the back and back of a member and improve the production efficiency and quality of the pellets.

[0006]

In order to achieve the above-mentioned object, the present invention comprises an extrusion step of pressing a resin toward a die plate by an extruder to produce a rod-shaped resin, and the extruded rod-shaped resin. In the method for producing resin pellets, which includes a cutting step of cutting the resin into predetermined dimensions to produce pellets, and a cooling step of cooling the pellets obtained by the cutting step, the cutting step includes spraying mist-like water. Performed in a water atmosphere, the cooling step includes a step of cooling the pellets cut into predetermined dimensions by the cutting step into running water to separate water from the cooled pellets. A method for producing a characteristic resin pellet is provided.

Also, the method for producing resin pellets is characterized in that the step of separating water from the pellets is performed by a centrifugal separator type dehydrator.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for producing resin pellets according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a resin pellet manufacturing apparatus used in the method for manufacturing resin pellets according to the present invention.

The resin pellet manufacturing apparatus has the following structure. The extrusion molding machine 10 is composed of a cylinder 11 and a screw 12 that rotates inside the cylinder, and a die plate 13 having a plurality of through holes 14 is attached to the tip of the cylinder 11. A breaker 20 including a motor 21 and a rotary blade 22 attached to a tip of a rotary shaft 23 rotated by the motor 21 near the through hole 14 of the die plate 13, and the rotary blade 2.
Water mixing air nozzle 15 that sprays mist-like water toward 2
Is provided. The melt-kneaded resin 50 is fed into the cylinder 11 from a melt-kneader (not shown).

The cooling water supply port 1 is provided below the rotary blade 22.
8 is provided, the cooling water 19 is inclined so that the cooling water 19 naturally flows, and a cooling pipe 30 through which the cooling water flows at a predetermined depth is arranged. The end of the cooling pipe 30 is a centrifugal separation type dehydrator. 40
Are linked to. On the dehydrator 40 side of the cooling cylinder 30, a preliminary dewatering net 31 for adjusting the cooling water 19 entering the dehydrator 40 is provided.

The centrifugal type dehydrator 40 has a large number of holes 41.
A propeller blade 43 that is rotated by a motor 47 is provided inside the opened cylinder 42. A dehydrator drainage port 44 for discharging the separated water is provided below the dehydrator 40. A dehydrated pellet outlet 45 for taking out dried and dehydrated pellets is provided above the dehydrator 40.

A method of manufacturing resin pellets will be described. The resin 40 melted and kneaded in the cylinder 11 of the extrusion molding machine 10 is pressed against the die plate 13 side as the screw 12 rotates, and is extruded as a rod-shaped body from the through hole 14 of the die plate 13. The resin 50 extruded as a rod-shaped body is cut into a predetermined size by the rotary blade 22 rotated by the motor 21, and the pellet 6
0 is obtained. At this time, since mist-like water is sprayed from the water mixing air nozzle 15 toward the rotary blade 22,
The resin 50 extruded in a rod shape is cut in a water atmosphere. As a result, water droplets adhere to the surface of the generated pellets 60 and the surface of the pellets 60 is cooled, so that the pellets 60 do not adhere to each other or adhere to the back of the rotary blade 22 of the breaking machine 20.

Further, the atomized water has a much lower heat-removing effect than the case where the water is directly applied to the die plate 13, so that the temperature of the die plate 13 is not affected. Therefore, the productivity of the pellets 60 is not reduced by increasing the extrusion pressure of the extruder.

The pellet 60 whose surface has been cooled has a cooling cylinder 3 through which cooling water 19 introduced from a cooling water supply port 18 flows.
It falls to 0. The pellets 60 are carried to the dehydrator 40 while being cooled to the inside by the cooling water 19. Pellet 6
Pellets 6 by dropping 0 into the cooling water 19.
It is possible to prevent 0 deformation and mutual adhesion.

In the dehydrator 40, pellets 6 coming in from below the dehydrator 40 are rotated by rotating propeller blades 43 arranged inside a cylinder 42 having a large number of holes 41.
The pellet 60 is pushed upward while separating water on the surface of 0, and the dehydrated / dried pellet 60a is discharged from the dry pellet outlet 45. The pellets in the dehydrator are not shown. The separated water is discharged from the hole 41 to the outside of the cylinder 42, and from the dehydrator drain port 44 to the outside of the dehydrator 40 as indicated by an arrow 46.

When the amount of the cooling water 19 supplied from the cooling water supply port 18 is excessive as compared with the dehydrating capacity of the dehydrator 40, a preliminary dewatering net for adjusting the cooling water 19 entering the dehydrator 40. 31 is provided.

The resin used to produce pellets according to the present invention is
In addition to polyolefin resins such as ethylene-ethyl acrylate copolymer (EEA) and ethylene-vinyl acetate copolymer (EVA), rubber materials such as ethylene propylene diene rubber (EPDM) and rubber materials containing polyolefin are also manufactured. can do.

Here, in the case of producing resin pellets having a low melting point which are easily adhered to each other, the amount of water in the water-mixed air and the amount of cooling water are increased to suppress the pellets or the water content which are difficult to be dehydrated. If you want to produce pellets you need,
Measures such as reducing the amount of water in the water-mixed air and cooling water and heating the cooling water. By changing the cooling conditions in this way, it is possible to deal with various resins.

[0020]

As described above, according to the method for producing resin pellets of the present invention, when the resin extruded in the shape of a rod is cut into pellets, after spraying water-mixed air, the pellets are placed in running water. Since it was dropped and cooled, and water was separated from the cooled pellets, a rod-shaped body can be extruded without increasing the mechanical load of the extruder, and pellets can be generated without cutting the rod-shaped body. Furthermore, it was possible to prevent mutual deposition of pellets on the back of the blade of the breaking machine, etc., and to manufacture resin pellets with improved pellet production efficiency and quality.

[Brief description of drawings]

FIG. 1 is a view showing a resin pellet manufacturing apparatus used in a resin manufacturing method according to the present invention.

[Explanation of symbols]

10 Extruder 11 cylinders 12 screws 13 Dice plate 14 through holes 15 Water mixing air nozzle 18 Cooling water supply port 19 cooling water 20 breaking machine 21 motor 22 rotary blades 23 rotation axis 30 cooling tubes 31 Preliminary dewatering net 40 resin 40 dehydrator 41 holes 42 cylinders 43 Propeller-shaped blades 44 Dewatering machine drain 45 Dry pellet outlet 46 arrow 47 motor 50 resin 60 pellets 60a pellet

Claims (2)

[Claims] 1. An extrusion step of pressing a resin toward a die plate by an extruder to produce a rod-shaped resin, and a cutting step of cutting the extruded rod-shaped resin into a predetermined size to produce pellets. In the method for producing resin pellets, including a cooling step of cooling the pellets obtained by the cutting step, the cutting step is performed in a water atmosphere in which mist-like water is sprayed, and the cooling step includes the cutting. The pellets cut into a predetermined size by the step are dropped into running water and cooled,
A method for producing resin pellets, comprising the step of separating water from the cooled pellets. 2. The method for producing resin pellets according to claim 1, wherein the step of separating water from the pellets is performed by a centrifugal separator dehydrator.