KR101118021B1 - Extruding System for Manufacturing of Extruded Articles with Brilliant Gloss - Google Patents

Abstract

The present invention includes an extruder for plasticizing and extruding thermoplastic resin, a drawer for taking an extruded product at a predetermined speed, and a cutter for cutting the extruded product to a predetermined length, and is continuously located at a nozzle portion of the extruder. It consists of performing high gloss surface treatment on the surface of the extrudate simultaneously with extrusion by forming a steep temperature gradient between the hot die and the cold die which have a temperature difference between the end temperature of the hot die and the starting temperature of the cold die of 30 to 200 ° C. Relates to an extrusion system.

Description

Extruding System for Manufacturing of Extruded Articles with Brilliant Gloss}

1 is a schematic diagram of a conventional extrusion cooling system;

2 is a schematic cross-sectional view of an extrusion die and a vacuum cooling device of the extrusion cooling system of FIG. 1;

3 is a schematic diagram of an extrusion cooling system according to one embodiment of the present invention;

4 is a schematic cross-sectional view of an extrusion die and a vacuum cooling apparatus of an extrusion cooling system according to another embodiment of the present invention.

The present invention relates to an extrusion system for the production of high gloss extrudates, and more particularly, to an extruder for plasticizing and extruding a thermoplastic resin, a take-off for extruding the extrudate at a predetermined speed, and a predetermined length of the extrudate. And a cutting machine for cutting the die, wherein a hot die and a cold die are continuously formed at the nozzle portion of the extruder, and a rapid temperature gradient is formed at a temperature change interval between the hot die and the cold die, and the hot die at the temperature gradient. The end point temperature of the die and the starting point temperature of the low-temperature die have a temperature difference of 30 to 200 ° C., and a high gloss surface treatment is applied to the surface of the extrudate at the same time as the extrusion with a temperature change rate of 2 to 40 ° C./mm according to the progress direction in the temperature change section. It relates to an extrusion system to perform.

1 is a schematic view of a conventional general extrusion cooling system, and FIG. 2 is a partial schematic view of an extrusion die and a vacuum unit in the extrusion cooling system according to FIG. 1.

Referring to these drawings, the extruder 10, the extrusion die 20, the vacuum cooling device 30, the take-out machine 40, and the cutter 50 are arranged in the order of the traveling direction of the extrudate.

That is, the extrudate extruded in a molten state through the extruder 10 for plasticizing and extruding the mixed extrusion raw material by the stirrer 11 is external heating means along the nozzle 21 to form a predetermined shape. The extrudate is discharged in the state of high temperature from the extrusion die 20 through the extrusion die 20 in which 22 was mounted. At this time, in order to cool the profile of the shape extruded from the die at a high temperature and to solidify the shape, it is passed through the vacuum cooling device 30 and cut into the desired length by the cutter 50 via the take-off 40. As a result, an extrusion molded product can be produced.

However, since such extruded moldings have a low surface gloss, various methods have been used, such as adding a separate gloss agent or performing a surface treatment process to give high gloss to the surface of the extrudate.

For example, the method of adding glossiness by adding a hot wire to the die end part according to the shape of an extrudate is used. However, this method has a problem in that extrusion failure due to overheating occurs. As another example, the method of polishing the surface of the extrudate or the coating of a high gloss material is required as a surface treatment device as an additional step, so that not only increase the cost but also significantly reduce productivity, and the coating according to the surface treatment is uniform. There are many problems, such as the generation of defective products.

On the other hand, the vacuum cooling device 30 is a device for cooling the extrudate by circulating the refrigerant by the cooling water circulator 31, having a very long process length of about 3 to 6 m, bar space constraints Extrusion speed is about 3 to 5 m / min in the case of a large, vacuum cooling device, and there is a serious problem such as greatly reducing the production efficiency because there is a limit to increasing the take-up speed by vacuum cooling.

In this regard, Korean Patent No. 0538773 combines an auxiliary mold member having an air passage communicating with the outside at equal intervals with an extruded member, thereby immediately discharging gas and air generated from the inside during foam molding to high outside foaming. Disclosed is a technique related to an extrusion molding system for improving the efficiency according to the present invention, wherein the cooling water is circulated through the cooling water circulation hole at the same time as the foam molding to rapidly cool the outer surface of the molded product so that the surface treatment is performed. It includes.

However, the above technique does not disclose the specific details of the method of quenching the outer surface of the molded article, and according to the experiments of the inventors of the present application, in the extrusion molding system having the configuration in which the sizing member is provided at the front end of the mold member, As a very moderate temperature gradient was formed by heat conduction, it was confirmed that high gloss could not be exhibited even if the surface treatment of the extrudate was partially performed.

US Patent Application Publication No. 2004-0159966, on the other hand, is a method for producing an extrudate having a smooth surface, in which an extrusion die having a molten resin flow tube and a sizing device having a shaping flow channel having a smooth inner wall surface are combined. At least one heat conductive member is mounted in the extrusion die in the vertical direction of the molten resin flow tube, and the distal end portion of the heat conductive member is tapered through the shape flow tube so that the extrudate passes through the end portion of the heat conductive member. By keeping the molten portion inside the extrudate, while the extrudate solidifies by passing through the form flow tube of the sizing die, the surface of the extrudate is pressurized against the inner wall of the form flow tube to form a smooth outer surface due to the expansion pressure of the melt portion. Disclosed is a technique.

However, since the extrusion die and the sizing device are directly coupled to the above technique, despite the presence of a heat insulating portion, the thermal conductivity can not be fundamentally blocked, and thus has a very gentle temperature gradient, thereby giving a high gloss to the surface of the extrudate. Can not. In addition, the present invention provides a very complicated device in which a heat conduction member is installed inside the flow tube, but the heat conduction member lowers the flow flow characteristics of the extrudate, and thus the final manufactured extrudate does not have uniform physical properties. It is practically very difficult to mount the member stably, and there are many problems such as an increase in the installation cost, and thus there is a limit in practical use.

Further, as a technique for increasing the speed of extrusion molding, Japanese Patent Application Laid-Open No. 2001-113587 discloses that in order to prevent defects in the extrudate due to the thinning of the solidified layer when the extrusion speed is increased, By making the cross-sectional area of the resin passage smaller than the cross-sectional area of the molded part at the point where the solidification starts, the flow rate of the molten resin inside the solidified layer is faster than the speed at which the solidified layer pushes the wall surface of the sizing apparatus, thereby improving the extrusion molding speed. Suggesting.

However, the technique also has to be formed separately to reduce the cross-sectional area of the resin passage, there are a number of problems, such as lowering the flow flow characteristics of the extrudate, the process is complicated, the equipment cost increases.

In addition, Japanese Patent Application Laid-Open Publication No. 2002-086544 discloses, in order to solve the problem that the center of the extrudate is partially unsolidified and the extrusion rate cannot be improved, the process of cooling the hot extrudate is divided into two processes. A technique for mitigating a temperature gradient is disclosed. However, according to the above technique, since the temperature lowering section is lengthened, the length of the solidification process becomes very long, and thus, the speed of the extrusion process is lowered and there is a problem that the problem of space waste cannot be fundamentally solved.

Therefore, there is a high demand for a technology that can provide high gloss on the surface of the extrudate by a continuous process to the extrusion product, while preventing waste of space and manufacturing cost and increasing production efficiency.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

The inventors of the present application, after repeated in-depth studies and various experiments, the hot die and the cold die are continuously formed at the nozzle portion of the extruder, and a rapid temperature gradient is formed between the hot die and the cold die in the temperature change section. Based on this temperature gradient, when the end point temperature of the hot die and the start point temperature of the low temperature die are configured to have a predetermined temperature difference, it is found that high gloss surface treatment can be performed on the surface of the extrudate at the same time as extrusion, thereby completing the present invention. It came to the following.

Accordingly, the extrusion system according to the present invention includes an extruder for plasticizing and extruding a thermoplastic resin, a drawer for taking an extruded product at a predetermined speed, and a cutter for cutting the extruded product to a predetermined length, and the nozzle of the extruder. In the region, a relatively hot die ("hot die") and a relatively low die ("cold die") are continuously formed, and a rapid temperature gradient is formed in a temperature change section formed between the hot die and the cold die. In the temperature gradient, the end point temperature of the hot die and the start point temperature of the low temperature die have a temperature difference of 30 to 200 ° C., and a rate of change of temperature according to the direction of travel in the temperature change section is 2 to 40 ° C./mm. At the same time, the surface of the extrudate is subjected to high gloss surface treatment.

Extrusion system according to the present invention can be subjected to a high gloss surface treatment on the surface of the extrudate at the same time as extrusion, do not add a varnish or surface treatment process separately, do not use a vacuum cooler or use only a vacuum cooler of the minimum process length In this way, space waste of the extrusion system can be minimized, and the reduction of the extrusion speed can be prevented, thereby reducing the manufacturing cost and greatly improving the production efficiency.

That is, the extrudate rapidly solidifies due to the rapid temperature difference between the hot die and the cold die, and thus the density _C of the extrudate in the low temperature die becomes higher than the density _H of the extrudate in the hot die. Therefore, the moving speed V _C of the extrudate in the low temperature die is lower than the moving speed V _H of the extrudate in the high temperature die, and a rapid solidification occurs from the surface of the extrudate in contact with the low temperature die, and at this part, Since the pressure is generated by the strong shearing force, a large pressure is exerted on the extrudate in the low temperature die, and it is estimated that a gloss is formed on the surface of the extrudate by a kind of pressure pulling force.

The extrusion system according to the present invention forms an abrupt temperature gradient in the temperature change section formed between the end point temperature of the hot die and the cold die, where the "temperature change section" is formed between the hot die and the cold die. It refers to a section in which the temperature changes rapidly, which serves to prevent heat exchange between the hot die and the cold die.

Due to the sharp temperature gradient, the extrudate solidifies rapidly, resulting in a higher density of extrudate _C in the lower die than the density _H of the extrudate in the hot die. Therefore, since the moving speed V _C of the extrudate in the low temperature die is lower than the moving speed V _H of the extrudate in the high temperature die, a larger pressure is applied to the extrudate in the low temperature die by this difference. It is estimated that gloss is formed on the surface of an extrusion molding by a kind of pushing force. In addition, since the skin portion of the extrudate is solidified in a dense state, deformation of the extrudate does not occur even when an unsolidified portion is present in a part of the center portion of the extrudate, and there is no need to separately go through the vacuum cooling device.

The end point temperature of the hot die and the start point temperature of the cold die have a temperature difference of 30 to 200 ° C. as defined above. If the temperature difference exceeds 200 ° C., the extrusion may not be performed smoothly due to the rapid solidification of the extrudate, and thus the manufacturing process may not proceed.

The temperature change rate according to the advancing direction of the extrudate in the temperature change section, for the high gloss effect of the extrudate and the smooth progress of the process, should be 2 to 40 ℃ / mm in the calculation of the following formula (1). In addition, the length of the temperature change section is preferably 1 to 150 mm.

T _L = (T _H -T _C ) / L (1)

Where T _L is the rate of change of temperature, T _H is the end point temperature of the hot die, T _C is the start point temperature of the cold die, and L is the length of the temperature change section.

When the rate of change of temperature is less than 2 ° C./mm or exceeds 150 mm, the rate of change of temperature is moderated between the hot die and the cold die, and thus the solidification of the extrudate gradually occurs so that the density of the extrudate is lowered to give surface gloss. It is not preferable because it cannot be exhibited.

On the other hand, the larger the rate of change of temperature is preferable, the shorter the length of the temperature change section is preferable, but expensive equipment is required to set a very large temperature change rate and a very short temperature change section. Therefore, the temperature change rate and the length of the temperature change section are preferably set as described above.

In order to set the temperature as described above, the high temperature die and the low temperature die may include separate temperature control means.

Specifically, the end portion of the hot die may preferably include a heating means for preventing the temperature drop. The heating means may be formed inside the hot die or may be formed together inside and outside the hot die. It does not specifically limit as said heating means, For example, a normal electric heating element etc. can be used.

The end point temperature of the hot die may be appropriately adjusted according to the type of extrusion raw material to be extruded, and preferably, may be 150 to 250 ℃. When the end temperature of the hot die is less than 150 ° C., the extrudate solidifies gradually, and thus it may not have a dense density. Thus, the desired surface gloss cannot be exhibited. On the other hand, when the temperature exceeds 250 ° C., the deterioration of the thermoplastic resin It is not preferable because it may occur.

In addition, it is preferable that a cooling means for preventing a temperature rise is included in the viewpoint portion of the cold die. The cooling means may be formed only inside the cold die, or may be formed together inside and outside the cold die. The cooling means is not particularly limited, and for example, a cooling device such as a pipeline through which a refrigerant flows can be used.

The viewpoint temperature of the low temperature die may be appropriately adjusted according to the type of the thermoplastic resin, it is preferably maintained at a level slightly higher than the melting point or softening point of the thermoplastic resin, more preferably, may be 40 to 150 ℃. If the low temperature die temperature is less than 40 ° C., the manufacturing process is difficult to proceed due to rapid solidification. On the contrary, if it exceeds 150 ° C., the temperature difference with the high temperature die is small and the solidification of the extrudate is insufficient. This is because the gloss cannot be obtained.

The thermoplastic resin is not particularly limited as long as it is an extrudable thermoplastic resin such as polyethylene, acrylic resin, vinyl chloride resin, vinyl acetate resin, vinylacetyl resin, polyamide resin, and celluloid resin, and preferably acrylonitrile-butadiene-styrene ( ABS) copolymer, polycarbonate (PC), polyvinylchloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), polyester, polypropylene, and one or more selected from the group consisting of nylon It may be a polymer.

In addition, the thermoplastic resin includes an unfoamed foam and a foam, and when producing the foam using the extrusion cooling system according to the present invention, it may be preferably a fine foam. Such a fine foam is preferably, as disclosed in the applicant's Korean Patent Application No. 2005-115637, the pores of the skin portion of the fine foam has a finer structure than the pores of the core portion, It may be dense and have similar mechanical properties as the non-foamed sheet. The contents of this application are incorporated herein by reference.

The temperature change of each of the hot die and the cold die is preferably 5 ° C., more preferably maintained within ± 2 ° C. This is because when the temperature change exceeds ± 5 ° C., a uniform extrudate cannot be obtained and the mechanical properties of the extrudate are lowered.

On the other hand, when the high temperature die and the low temperature die is integrally included in one extrusion die (Die), it is more efficient because the length of the temperature change section can be minimized.

In one preferred example, a short process length vacuum cooler may optionally be included between the extruder and the take-off.

In other words, if the extrudate solidified in a low temperature die is additionally cooled and solidified, it may be optionally passed through a vacuum cooler. The vacuum cooler has a relatively short process length. Compared with the vacuum cooling device, the process length may be shorter than 3 to 6 m so that the process length may be short, and preferably, the process length may be 2 m or less.

In some cases, it may be configured to further include a coolant circulator (chiller) for supplying the coolant to the vacuum cooler and / or cooling means. The cooling water circulator is generally connected to a cooling water tank, and is cooled in the extrudate by repeating a process in which cooling water is introduced and circulated through the inlet formed on one side of the vacuum cooler and / or cooling means and discharged through the outlet formed on the other side. This is done.

The cooling water circulator is not particularly limited, and a known cooling water circulator may be used, and its configuration and principle are known in the art, and thus description thereof is omitted herein.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

Hereinafter, the present invention will be further described with reference to the drawings, but the scope of the present invention is not limited thereto.

Figure 3 schematically shows an extrusion cooling system according to an embodiment of the present invention, Figure 4 is a partial schematic view of the extrusion die and vacuum cooling apparatus of the extrusion cooling system according to another embodiment of the present invention. Is shown.

Referring to these drawings, the extrusion cooling system is configured in the order of the extruder 100, the extrusion die 200, the vacuum cooling device 300, the take-off 400 and the cutter 500 according to the direction of the extrudate. .

Specifically, the extrusion raw material mixed by the stirrer 110 is melt plasticized while passing through the extruder 100, and is extruded into a predetermined shape through the extrusion die 200.

The extrusion die 200 is a high temperature die 250 with the internal heating means 220 and a low temperature die 260 with the cooling means 230 mounted therein in succession to the high temperature die 250. consist of.

A temperature change section exists between the high temperature die 250 and the low temperature die 260. The rapid temperature gradient causes rapid solidification from the surface of the extrudate in contact with the low temperature die 260, thereby causing the extrudate to The surface solidifies to a dense density. Therefore, pressure is generated due to the strong shear force with the surface of the extrudate at this portion, and also due to the solidification of the extrudate as described above, a difference in extrusion speed is caused in the hot die 250 and the cold die 260. Accordingly, when a large pressure is applied to the extrudate, the surface of the extrudate exhibits high gloss by a kind of force of attraction.

On the other hand, optionally, if the extrudate requires further cooling and solidification, the extrudate passed through the low temperature die 260 may be passed through the vacuum cooling device 300, wherein the vacuum cooling device 300 is about 2 m It can have a short process length below. Therefore, it is possible to prevent the space waste of the extrusion system, to reduce the manufacturing cost, and to increase the extrusion speed as the process length is reduced, the production efficiency is very excellent. Meanwhile, the coolant circulator 310 is connected to the low temperature die 260 and / or the vacuum cooling device 300 so that the refrigerant may be circulated to cool and solidify the extrudate.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

[Examples 1 to 4]

A extrusion apparatus and an extrusion die in which a temperature controllable high temperature die, a temperature change section, and a low temperature die are integrally mounted are mounted on a twin screw extruder to prepare an extrusion apparatus for extruding a thermoplastic resin. At this time, the length of the hot die was 125 mm, the length of the temperature change section was 27 mm, and the length of the cold die was 40 mm. 98 parts by weight of hard polyvinyl chloride (PVC) compound (manufactured by LG Chemical) was introduced into the extruder to completely plasticize the PVC, and then 2 parts by weight of nitrogen was injected into the barrel of the extruder using a high pressure pump, and a mixture of single phase Was molded to prepare a PVC sheet having a thickness of 2 mm and a width of 100 mm.

The extruder conditions were such that the temperature of the barrel was 190 ° C-180 ° C-175 ° C, and the temperature of the adapter was maintained at 130 ° C. In addition, the conditions of the high temperature die, the temperature change section, and the low temperature die are summarized in Table 1 below.

Comparative Example 1

Instead of using an extrusion die in which a temperature-controlled high temperature die, a temperature change section, and a low temperature die are integrally formed, a conventional extrusion die composed of only a high temperature die is used, and cooling is performed using a vacuum cooling device of about 4 m in length. A PVC sheet was produced in the same manner as in Example 1, except that it was performed. The conditions of the hot die are shown in Table 1 below.

TABLE 1

Experimental Example 1

In Example 1 to 4 and Comparative Example 1, the extrusion rate was measured in the process of extruding the PVC sheet, and the results are shown in Table 1 above.

As shown in Table 1, it can be seen that the extrusion speed of Examples 1 to 4 without using the vacuum cooling device is equivalent to the extrusion speed of Comparative Example 1 using the conventional vacuum cooling device, or about 10 to 15%. .

Experimental Example 2

The glossiness of the PVC sheet of Examples 1 to 4 and the PVC sheet of Comparative Example 1 was measured using the specular gloss measurement method of KS L 2405, and the results are shown in Table 2 below. Gloss measurement instrument was used Gardner's micro-tri-gloss meter.

TABLE 2

As shown in Table 2, the glossiness of the PVC sheet of Examples 1 to 4 was very high in all areas of 20 °, 60 °, 85 ° compared to the glossiness of the PVC sheet of Comparative Example 1, in particular The glossiness measured at 20 ° was found to increase more than two times.

Therefore, the process of manufacturing a high gloss extrudate can be given a surface gloss by a series of extrusion process without going through a separate glossing process, it can also improve the extrusion speed, it is confirmed that the productivity can be greatly improved It was.

While the above has been described above with reference to embodiments according to the present invention, those of ordinary skill in the art to which the present invention pertains can make various applications and modifications within the scope of the present invention. will be.

As described above, in the extrusion system according to the present invention, that is, the hot die and the cold die are continuously formed in the nozzle portion of the extruder, and the hot die is formed so as to form a sharp temperature gradient in the temperature change section between the hot die and the cold die. By setting the end point temperature of the die and the starting point temperature of the low temperature die to a predetermined temperature difference, it is possible to produce an extruded molding having a high gloss surface without adding a separate polish or surface treatment process, and may not include a vacuum cooling device. Therefore, it is possible to prevent the waste of space, to reduce the cost of extrusion production, and to improve the extrusion speed, which is very excellent in terms of production efficiency.

Claims (13)

It includes an extruder for plasticizing and extruding thermoplastic resin, a drawer for drawing the extruded product at a predetermined speed, and a cutter for cutting the extruded product to a predetermined length, and the nozzle portion of the extruder has a relatively hot die (" Hot die ") and a relatively low die (" cold die ") are continuously formed, and the end point temperature of the hot die and the start point temperature of the cold die have a temperature difference of 30 to 200 캜, and the hot die and the The temperature change rate according to the advancing direction in the temperature change section between the low temperature dies is 2 to 40 ° C./mm in the calculation of Equation 1 below, and the extrusion system is characterized in that the high gloss surface treatment is performed on the surface of the extrudate simultaneously with the extrusion. T _L = (T _H -T _C ) / L (1) Where T _L is the temperature change rate, T _H is the end point temperature of the hot die, T _C is the start point temperature of the cold die, and L is the length of the temperature change section. The extrusion system according to claim 1, wherein the temperature change section has a length of 1 to 150 mm. The extrusion system according to claim 1, wherein the end portion of the hot die includes a heating means for preventing a temperature drop. The extrusion system of claim 1, wherein the end point temperature of the hot die is 150 to 250 ° C. 2. The extrusion system according to claim 1, wherein cooling means for preventing a temperature rise are included at the time point of the cold die. 2. The extrusion system of claim 1, wherein the starting temperature of the cold die is between 40 and 150 degrees Celsius. The extrusion system of claim 1, wherein the temperature change of the hot die and the cold die is 5 ° C. 2. An extrusion system according to claim 1, wherein a vacuum cooler of short process length is optionally included between the extruder and the drawer. 9. The extrusion system of claim 8, wherein the vacuum cooler has a length of 2 m or less. 6. An extrusion system according to claim 5, further comprising a cooling water circulator for supplying cooling water to said cooling means. The method of claim 1, wherein the thermoplastic resin is acrylonitrile-butadiene-styrene (ABS) copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), Extrusion system, characterized in that one or more polymers selected from the group consisting of polyester, polypropylene, and nylon. The extrusion system according to claim 1, wherein the thermoplastic resin is mixed with a blowing agent to produce an extruded molding of the micro-foam. 10. The extrusion system of claim 8, further comprising a coolant circulator for supplying coolant to the vacuum cooler.

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