KR100433767B1 - Apparatus for manufacturing foamed thermoplastic resin pellets - Google Patents

Abstract

The present invention relates to a device for producing a pellet-type thermoplastic resin foam which can form a free-standing pores well and can be continuously foamed, the die having a cylindrical body, and the outer peripheral surface and the outer peripheral surface A top feed forming a plurality of resin flow paths radially disposed at regular intervals between the cylindrical body inner circumferential surfaces of the die, and a plurality of radially formed radially spaced at regular intervals on the cylindrical body of the die along the resin flow paths. Means for continuously cutting and molding the resin extruded through radially extruded holes of the die into pelletized resin foams of a predetermined size, disposed in the extrusion holes of the die and radially extruded holes in the die body. Wherein the means comprises all or part of the length of the die A guide protruding symmetrically from each other with respect to the extrusion holes on a main surface thereof; Operating members slidably inserted along the guide; Both ends are fixed to the upper edges of the surface facing each other of the operating members, the widthwise center is formed to be curved downward to contact the tangential direction of the extrusion holes and a plurality of through holes in communication with the extrusion holes along the longitudinal direction is formed It is configured to include a cutting knife.

The present invention can form a good free-standing pores and can be continuously foamed pellets in bulk without a separate foaming intermediate product forming process.

Description

Apparatus for manufacturing pellet-type thermoplastic resin foam {APPARATUS FOR MANUFACTURING FOAMED THERMOPLASTIC RESIN PELLETS}

The present invention relates to an apparatus for producing a pellet-type thermoplastic resin foam, and more particularly, a die for extruding and foaming a resin material in the radial direction of a cylindrical body and a cutting for continuously cutting and molding the extruded foam from the die into pellets of uniform size and shape. The present invention relates to an apparatus for producing a pellet-type thermoplastic resin foam which is provided so that a relatively high viscosity thermoplastic resin can be inexpensively mass-molded in a small pellet form.

Pellet-type thermoplastic foam has good moldability to products with complex shapes, and features excellent cushioning and durability against repeated impact, hard and smooth surface, excellent chemical resistance and moisture resistance. It is widely used for molding products for various applications such as carrying cases, cushioning materials for shock absorption, cushioning materials for vehicles, buoys, and the like.

Conventionally, such thermoplastic resin foams are usually prepared by melt-extrusion of a linear resin melt-extruded using polystyrene or a copolymer of polystyrene with another resin to form pellets, which are intermediate products, and include warming / pressurization. After the foam molding process was prepared by the method of foam molding to the final foam.

This manufacturing method has been commonly used because it is easy to manufacture pellets, but once the foamable resin pellets have to be made through a two-step manufacturing process of foam molding again, the overall process and equipment are complicated, and using The use of these products is increasingly regulated because they emit pollutant gases when incinerated.

Therefore, in recent years, thermoplastic resin pellets are manufactured using materials such as low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), polypropylene (PP), and the like as thermoplastic resin materials that do not emit polluting gases. Doing.

Since the thermoplastic resin pellets have a high viscosity of resin materials such as LDPE and L-LDPE, they are difficult to be manufactured by conventional cutting methods, and the foaming agent is mixed with plastic particles in a small amount of individual reaction method, and foamed after heating and pressing. Was manufacturing.

To explain this in more detail, the resin pellets are made according to the expansion ratio and the size of the foamed particles, and many small resin pellets are poured into the drum container in order to form the foamed particles therein. It is a method of obtaining foamed particles intermittently by intermittently heating, pressurizing to high pressure, kneading for several minutes (5-30 minutes), and then foaming introductoryly after the foaming agent has sufficiently infiltrated the resin particles.

Therefore, such a small amount of foaming method has a problem that it is difficult to continuously mass-produce the production cost of the foam particles, as well as the size of the foam particles pellets is not uniform.

In general, foams such as polystyrene are not difficult to produce in pellet form, but thermoplastic resins such as low density polyethylene and linear low density polyethylene and polypropylene have high viscosity and are difficult to cut into pellets. The bur is cut in the form of remaining, it is not possible to obtain a good quality pellets and there is a problem that the uniformity is greatly reduced. Therefore, there is a great demand for a means that can economically and practically achieve uniform pelletization while continuously foaming thermoplastic resin having high viscosity.

Accordingly, the present inventors enable continuous foam molding in pellet form while mixing and extruding a thermoplastic resin and a blowing agent, thereby continuously molding the desired pellet-type thermoplastic resin foam directly from the resin material without forming a separate foamable intermediate product. The device has been researched and patented as Korean Patent No. 135899 and also registered as Korean Utility No. 183571. The present invention further improves the manufacturing performance of the desired foam further.

The patent application is a die in which the thermoplastic resin and the blowing agent are melt-mixed and press-supplied from the inlet side to the inside, and a plurality of radial extrusion holes are formed at the outlet side, and one side is fixed to the outlet side end of the die. And a spindle-shaped top feed coupled to the other side so as to extend to the inner center of the die, and a linear foam that is rotatably coupled to the outer side of the die to be extruded and foamed through radial extrusion holes of the die. And a cutter for making a resin foam, wherein the cutter includes plate-shaped blades which tangentially contact an outer circumferential surface of a die in which the radial extrusion holes are formed. It is describing.

However, since the blades should be installed on the outer circumferential surface of the cylindrical die along the length of the die, the blades of each plate-shaped blade of the cutter should be installed correctly to smoothly perform the required cutting action. Very difficult; In addition, the blade blade structure is rotated along the die surface with the blade blade structure in contact with the die surface without any gap, and the blade blade is repeatedly cut in a state where the blade blade receives considerable impact force continuously when cutting the extrudate by the blade blade. This blade blade is liable to be worn and broken prematurely because of this, and noise and vibration are severe; At the same time, the frictional heat generated by the rotating plate blades acts on the die and the extrudate through the die, causing severe frictional heat due to the contact rotation between the die and the blade. At the same time, it is difficult to obtain good foaming conditions, and at the same time, the shape of the foam pellets is irregular due to the influence of airflow by the rotating blades.

The patent application of the patent application is that the cutting means of the configuration of the patented device is composed of a steel wire, for example, to be installed so as to be in close contact with the outer circumferential surface of the die in which the extrusion holes are formed along the curved surface of the outer circumference. In another possible embodiment, two radially adjacent extrusions on the die body are arranged to reciprocate in one direction along the length of the die or vice versa in a portion where the radial extrusion holes of the die body are formed. The working rods formed of a plurality of pairs of holes alternately communicating with the holes and a means capable of driving the same solve the problem of the patented device.

However, in the case of the improved utility model, it is easy to install and minimize the generation of frictional heat when cutting steel is used. Since there is little air flow, it is possible to suppress the deformation of the foam pellets due to the air flow, but the foam by the impact of the steel wire Because of the cutting, the overall shape and size of the obtained pellets were not uniform, and the use of the operating rods resulted in an excellent effect by overcoming the shortcomings of the above-described cutting steels, but did not form good independent pores. In other words, a separate problem has been identified that degrades its value as a packaging material.

The present invention has been made in order to effectively improve the problems and shortcomings of the above-described prior patent invention and pre-registered design to provide a device capable of exhibiting the production performance of a more excellent pellet-type thermoplastic resin foam.

1 is a cross-sectional view of a pellet type thermoplastic resin manufacturing apparatus according to the present invention,

2 is a general configuration diagram of an apparatus according to the present invention,

3 is a partial perspective view of a die portion of the apparatus according to the present invention;

4 is a cross-sectional view taken along the line A-A of FIG.

Figure 5 is a perspective view of the cutting means of the device according to the invention.

Explanation of symbols on the main parts of the drawings

1: dice 2: top feed

3: resin flow path 4: extrusion hole

5: operating member 9: driving motor

10: cutting knife 12: through hole

20: guide

The present invention for achieving the above object is to form a plurality of resin flow paths which are radially arranged at regular intervals between the die having a cylindrical body and the inner circumferential surface of the die and the outer peripheral surface and the inner peripheral surface of the cylindrical body of the die. A plurality of extrusion holes provided in a radial direction at regular intervals in the cylindrical body of the die along a top feed, each resin flow path, and in a portion where radial extrusion holes in the die body are formed. And means for continuously cutting the resin extruded through radially extruded holes of the die into pellet-shaped resin foams of a constant size, the means being extruded to the entire circumference of the die in its entirety or part of its length. A guide protruding symmetrically with respect to the holes; Operating members slidably inserted along the guide; Both ends are fixed to the upper edges of the surface facing each other of the operating members, the widthwise center is formed to be curved downward to contact the tangential direction of the extrusion holes and a plurality of through holes in communication with the extrusion holes along the longitudinal direction is formed Provided is a device for producing a pellet-type thermoplastic resin foam comprising a cutting knife.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

First, the thermoplastic resin which can be applied in the present invention is a conventional polystyrene, styrene-acrylonitrile interpolymer and styrene-ethylene interpolymer, and the like, low density and linear low density polyethylene, polypropylene, ethylene-propylene interpolymer, ethylene-vinyl acetate hybrid Polymers, polyvinyl chloride, and the like, and those made of interpolymers alone or in combination may be used.

In addition, a blowing agent applied to the present invention may be used a volatile or degradable blowing agent. Examples of the highly volatile blowing agent include aliphatic hydrocarbons such as propane, butane, isobutane, and pentane, substituted aliphatic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane, methyl chloride, methylene chloride, dichlorofluoromethane and chlorotri Fluoromethane, dichlorodifluoromethane and the like can be used, and dinitrosopentamethylenetetraamine, trinitrosotrimethylenetriamine, benzene sulfonylhydrazide, azodicarbonamide and the like can be used as the degradable blowing agent. These blowing agents can be used independently or in combination.

The thermoplastic resin, the blowing agent and other additives, etc., are made into the thermoplastic resin foam mixture by passing through an extruder.

That is, in the extruder configured by inserting a mixer between the main extruded part and the cold extruded part, the thermoplastic resin raw material is first supplied to the main extruded part and melted and transferred to the mixer by screw operation. The blowing agent is uniformly dispersed and mixed in the thermoplastic resin by indentation, mixing and stirring.

According to the kind of thermoplastic resin raw material, the main extrusion part is used, for example, in the case of low-density polyethylene, adjusted to a temperature of 100-200 ° C., and the mixer is set at the maximum temperature and pressure.

Thereafter, the foam mixture is continuously foamed into pellet form by the apparatus of the present invention as shown in FIGS.

1 to 5 show the configuration of an apparatus according to an embodiment of the present invention.

The device comprises a die 1 consisting of a cylindrical body of a hollow body and a plurality of resins disposed radially at regular intervals between an outer circumferential surface of the die 1 and an inner circumferential surface of the cylindrical body of the die 1. A top feed 2 for forming the flow paths 3 and a plurality of extrusion holes provided radially at regular intervals along the respective resin flow paths 3 in the cylindrical body of the die 1; 4) pellets of a predetermined size are disposed in the area where the radial extrusion holes 4 in the die 1 body are formed and extruded through the radial extrusion holes 4 of the die 1. And cutting means for continuous cutting and molding into mold resin foams.

The cutting means is configured to achieve the oscillation movement of the operating members 5 and the actuating members 5 disposed to reciprocate the oscillating movement in one direction or the opposite direction along the longitudinal direction of the die 1. It is configured to include drive means.

There may be a variety of means for vibrating the operating members 5 as desired by the present invention. As one possible example, as shown in FIG. 2, rotationally actuated by the driving motor 9 is possible. A circular eccentric cam 32 is installed on the rotation shaft 31, and a crank 33 is connected to the eccentric cam 32 by bearing one end of the same crank 33, and the operating member 5 is installed. Means of connecting the connecting rod 35 between the center of the support plate 34 and the end of the crank 33 by fixing the end of the crank 33 side to the one support plate 34. Can be.

Although the connecting state of the connecting rod 35 is illustrated in FIG. 2 in a schematic manner, an eccentric rotational movement of the eccentric cam 32 on the rotation shaft 31 and a crank 33 along the rotational movement of the eccentric cam 32 are shown. The connection between the connecting rod 35 and the support plate 34 is made through a connecting means, for example a universal joint, in order to enable the oscillating motion of the element to be transmitted in a linear reciprocating motion of the actuating members 5.

3 to 5, the cutting means has a pair of guides 20 protruding symmetrically to both sides of the plurality of extrusion holes 4 formed at regular intervals on the outer circumferential surface thereof in the radial direction of the die 1, The guide 20 is provided with a pair of movable members (5) slidable along the guide 20, both ends of the width of the cutting knife (10) at the upper edge side of the surface facing each other of the operating member (5) It is fixed.

The guide 20 is preferably formed one each at the front and rear ends of the die (1).

The operating member 5 is rotated 90 degrees in order to prevent it from being easily separated from the guide 20 by vibrating forward and backward in the longitudinal direction of the die 1 by the driving of the drive motor 9 described above. It is preferable to form to have a shape.

The upper edge of one side of the operating member 5, that is, the upper edges of the surfaces of the operating member 5 which are disposed around the extrusion hole 4, is inclined to cut the cutting knife 10 to easily bolt ( 14) It is more preferable to have a shape that can be fixed.

The cutting knife 10 preferably uses a heat-treated metal having wear resistance and corrosion resistance. The cutting knife 10 has curved portions 12b having bows curved in a downward direction with respect to the center portion thereof in a width direction, and a plurality of cutting knives 10 in the length direction thereof. The through hole 12, the sealing portion 12c formed between the through holes 12 and the bolt hole 18 has a structure formed.

The curved portion 12b refers to a line connecting width center points in the longitudinal direction of the cutting knife 10.

In addition, the through hole 12 is preferably formed to be approximately 20 to 30 times larger than the diameter of the extrusion hole 4 in consideration of the volume expansion of the foam foamed through the extrusion hole (4).

In addition, the cutting knife 10 is particularly preferably installed so that the curved portion 12b is in contact with the extrusion hole 4 of the die 1 in the tangential direction thereof.

In addition, a portion of the periphery of the through-hole 12 is the center of the pellet to the lower side of the extruded foam pellets when the cutting knife 10 is operated, for example, when oscillating back and forth about 2 ~ 3mm by the operating member 10 Both ends of the pellets cut by squeezing toward the end are sealed to perform a function as the cutting part 12a to maintain the independent pores.

In the operation of the apparatus according to the embodiment of FIGS. 1 to 5, the resin material mixed with the blowing agent is a resin flow path 3 between the die 1 and the top feed 2 located in the center of the die 1. The dies 1 are pressed into the die 1 and extruded out of the die 1 through extrusion holes 4 radially penetrating through the resin flow passages 3 in the radial direction. You lose.

At this time, if any one of the through holes 12 of the through holes 12 on the cutting knife 10 is in a state of communicating with one extrusion hole 4 on the body of the die 1, the remaining extrusion holes adjacent to this ( 4) is blocked by the sealing portion 12c of the cutting knife 10 is in a state where the extrusion of the resin material through it is temporarily stopped.

To this end, the extrusion holes 4 are formed in a pair of two in close proximity to the through hole 12 and the sealing portion 12c.

For example, with reference to FIG. 5, one extrusion hole 4 is formed at the rightmost side along the curved portion 12b of one of the through holes 12 formed in the cutting knife 10 and the other extrusion is adjacent thereto. The holes 4 are preferably located in the closed part 12c outside the through hole 12 so that two sets of extruded holes 4 are separated by almost the diameter of the through hole 12, and a plurality of pairs are formed.

At the same time, when the driving motor 9 is operated, the rotary shaft 31 is rotated by receiving the rotational force of the driving motor 9, and thus the eccentric cam 32 installed on the rotary shaft 31 is rotated ( 31, while the eccentric rotation around the central axis of the crank 33 is connected to the rocking movement is installed, this rocking movement of the crank 33 is transmitted to the support plate 34 through the connecting rod (35). Thus, the operation members 5 having end portions connected to and fixed to the support plate 34 are reciprocally oscillated from side to side in the drawing on the outer peripheral surface of the die 1 body.

The through hole 12 and the sealing portion 12c of the cutting knife 10 interlocked according to the vibrating movement of the operating members 5 are formed in two adjacent extrusion holes 4 formed in pairs of the die 1 body. Opening and closing alternately, the resin material is linearly extruded and foamed toward the outside of the die 1 through the through hole 12 communicated with the extrusion hole 4 of the die (1) body. The linear extruded foam that is extruded to meet the cutting portion 12a of the cutting knife 10 interlocked with the vibration movement of the operating member 5 has a size corresponding to the vibration speed of the operating member 5. After being cut into pellets, it is discharged out of the die 1.

Since a large number of radially extruded holes 4 along each resin flow path 3 are formed in a plurality of radial positions on the body of the die 1, a large amount of pellets is used for each vibration movement of the operating members 5. The type thermoplastic resin foam is formed and discharged outside the die 1.

On the other hand, the cutting part 12a is pressure-cutting the lower side of the extrudate toward the longitudinal center of the extrudates while alternately vibrating in the left and right direction to seal the both ends of the pores generated inside the pellet during foaming to make independent pores.

At this time, the cutting condition is that the extrudate is cooled while being cut while being heated to a melting point (MELTING POINT), so that both ends of the pore portion are closed at the same time as the cutting part 12a.

As described in detail above, the manufacturing apparatus of the present invention provides the following effects.

First, since the cutting knives are cut by the fine vibration, it is possible to form independent pores in the pellet, which has the advantage of maximizing the reliability of the material.

Second, the desired pellet-type thermoplastic foam can be foamed continuously in bulk without a separate foaming intermediate product molding process.

Third, even in the case of high viscosity foaming resin, which was difficult to foam foam due to high viscosity, continuous foaming is possible in pellet form.

Fourth, the generation of noise, vibration, frictional heat and airflow by means of continuously cutting the foam into pellets can further improve the quality and uniformity of the product.

Claims (3)

And a plurality of resin flow paths 3 disposed radially at regular intervals between a die 1 having a cylindrical body and an inner circumference of the die 1 and disposed between the outer circumferential surface and the inner circumferential surface of the cylindrical body of the die 1. A plurality of extruded holes 4 formed in a radial direction at regular intervals in the cylindrical body of the die 1 along the resin flow paths 3 and the top feed 2 to be formed; The resin extruded through the radially extruded holes 4 of the die 1 is disposed in a portion where the radially extruded holes 4 in the body of the die 1 are formed to continuously form pellet-shaped resin foams of a constant size. A guide (20) configured to include cutting means, the means protruding symmetrically from each other about the extrusion holes (4) on the entire peripheral portion of the die (1) or the entire longitudinal direction thereof; Operating members (5) slidably inserted along the guide (20); Both ends are fixed to upper edges of the operating members 5 facing each other, and the center in the width direction is downwardly curved to tangentially contact the extrusion holes 4 and the extrusion holes 4 along the longitudinal direction. Apparatus for producing a pellet-type thermoplastic resin foam, characterized in that it comprises a cutting knife (10) formed with a plurality of through holes (12) communicated with each other. delete The apparatus of claim 1, wherein the through hole (12) has a diameter of 20 to 30 times larger than that of the extrusion hole (4).