KR20080053535A - Extruding cooling system - Google Patents

Abstract

An extrusion cooling system is provided to cool and harden an extruded product when being extruded by using high and low temperature dies installed side by side at a nozzle part of an extruder. An extrusion cooling system comprises an extruder, a winder(400), a cutter, a heating unit(220), a cooling unit(230), and low and high temperature dies(250,260). The extruder extrudes plasticized extruded material. The winder winds an extruded product at a predetermined speed. The cutter cuts the extruded product by a predetermined size. The low and high temperature dies are installed at a nozzle part of the extruder side by side. Because the final temperature of the high temperature die is different from the initial temperature of the low temperature die by 30~200°C based on 2~40°C/mm of sudden variation rate of temperature, the extruded product cools off and hardens as soon as being extruded.

Description

Extruding Cooling System

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.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion cooling system, and more particularly, to an extrusion machine for plasticizing and extruding an extrusion raw material, a drawer for taking an extrusion molding at a predetermined speed, and a cutter for cutting the extrusion molding to a predetermined length. In the extrusion cooling system, a hot die and a low temperature die having a temperature difference of 30 to 200 ° C. with the hot die are continuously formed at the nozzle portion of the extruder, thereby cooling and shape solidifying the extrudate simultaneously with the extrusion. The present invention relates to an extrusion cooling system, which may not include a vacuum cooling device, so that space constraints may be overcome, manufacturing costs may be reduced, and extrusion speed may be increased, thereby greatly improving production efficiency. .

FIG. 1 schematically shows a conventional extrusion cooling system, and FIG. 2 shows a partial schematic of an extrusion die and a calibration 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.

In order to produce the extrudate, the extrusion raw material is first mixed with the stirrer 11, and the mixed mixture is extruded in a molten state by passing through the extruder 10, along the nozzle 21 to form a predetermined shape. The extrudate passes through the extrusion die 20 equipped with the external heating means 22 and flows out of the extrusion die 20 at a high temperature. Then, to cool the profile of the shape extruded from the die in a high temperature state and to pass the vacuum cooling device 30 to solidify the shape, it is cut through the take-out 40 to the desired length by the cutter 50. By this, an extrusion molding can be manufactured.

In this extrusion cooling system, 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, The space constraints are large, and the extrusion speed is about 3 to 5 m / min when subjected to the vacuum cooling device, there is a serious problem, such as greatly reducing the production efficiency because there is a limit to increase the take-up speed by vacuum cooling.

On the other hand, in connection with an extrusion molding apparatus for thermoplastic resins, Japanese Patent Application Laid-Open No. 2002-086544 has conventionally performed a cooling process having a relatively rapid temperature gradient, whereby the center of the extrudate becomes partially unsolidified, thereby improving the extrusion molding speed. In order to solve the problem that could not be solved, by performing a sequential cooling by performing the process of cooling the high-temperature extrudate in two times, to disclose a technique for reducing the temperature gradient to improve the speed and productivity of the extrusion process . That is, by cooling the melt extrudate first to 150 to 180 ° C. and subsequently to 60 to 140 ° C., a cooling process of a gentle continuous temperature gradient is proposed. However, in the above technique, the temperature is lowered to the temperature of the hot die by cooling, resulting in an increase in the length of the lowering section, and the length of the solidification process becomes very long, thereby reducing the speed of the extrusion process and fundamentally eliminating the problem of waste of space. There is a problem that can not be solved.

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.

After extensive research and various experiments, the inventors of the present application have continuously placed a hot die and a cold die at a nozzle portion of an extruder in an extrusion cooling system including an extruder, a drawer, and a cutter, and When set to a predetermined temperature difference of the rapid temperature gradient, the extrudate can be cooled and the shape solidified at the same time as the extrusion, and taken out by a take-out to improve the extrusion speed, and can optionally include a vacuum cooling device of short process length. Therefore, it has been found that the manufacturing cost can be reduced, and the production efficiency can be greatly improved, and the present invention has been completed.

Extrusion cooling system according to the present invention for achieving this object includes an extruder for plasticizing and extruding the extrusion raw material, a take-out to take the extrusion molding at a predetermined speed, and a cutter for cutting the extrusion molding to a predetermined length; In the nozzle portion of the extruder, 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 starting point temperature of the cold die are It is set to have a temperature difference of 30 to 200 ° C. at a rapid temperature change rate of 2 to 40 ° C./mm, and the extrudate is cooled and solidified at the same time as extrusion.

Therefore, the extrusion cooling system according to the present invention can perform the cooling and solidification of the extrudate simultaneously with the extrusion by the sharp temperature difference between the hot die and the cold die, and thus the extrusion speed can be improved. In addition, even when such a rapid temperature difference is formed, the temperature of the hot die is not lowered. Therefore, various problems that may occur due to a lower temperature of the high temperature die are lowered to a temperature of the high temperature die and thus a longer temperature drop section. . Moreover, the present invention can produce extrudates of desired physical properties even without using a vacuum cooling device or using a very short length vacuum cooling device, thereby minimizing waste of space in the extrusion system, and as a result, It can reduce the cost and greatly improve the production efficiency.

The end point temperature of the hot die and the start point temperature of the cold die according to the present invention, as defined above, is composed of a temperature difference of 30 to 200 ℃ at a rapid temperature change rate of 2 to 40 ℃ / mm, such a rapid Due to the temperature difference, the skin portion of the extrudate is solidified stably, so that even if an unsolidified portion is present in a part of the center of the extrudate, deformation of the extrudate does not occur, and there is no need to go through the vacuum cooling device separately.

If the temperature change rate is less than 2 ℃ / mm or the temperature difference is less than 30 ℃, the solidification is not achieved and the density of the extrudate is lowered and the surface properties of the extrudate is lowered, the extrudate of the desired physical properties may not be obtained . Conversely, if the rate of change of temperature exceeds 40 ° C./mm or the temperature difference exceeds 200 ° C., the manufacturing process may be difficult to proceed due to fluidity deterioration due to too rapid solidification of the extrudate and expensive equipment is required to set such conditions. It may not be desirable.

The section showing a sudden temperature difference between the hot die and the cold die by such a temperature change rate may be referred to as a "temperature change section" below.

The temperature change rate described above may be defined as a change in temperature according to the advancing direction of the extrudate in the temperature change section, which may be expressed by Equation 1 below.

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.

As the rate of temperature change in the temperature change section is higher, the density of the extrudate applied to the extrudate can be solidified in a denser state, so that an extrudate having excellent surface characteristics can be manufactured.

The length of the temperature change section may preferably be 1 to 150 mm in length. The shorter the temperature change section is, the more preferable it is. If it exceeds 150 mm, even if the temperature difference between the hot die and the cold die is set large, the rate of change of the temperature is small, which may cause the problems described above.

As a result, the temperature change section defined as above serves to prevent heat exchange between the hot die and the cold die so that a sharp temperature difference can be maintained between the hot die and the cold die.

Preferred examples of the method for setting the steep temperature difference between the hot die and the cold die include heating means for preventing the temperature drop at the end portion of the hot die, and cooling means for preventing the temperature rise at the time point of the cold die. The structure containing these is mentioned.

The heating means may be formed inside the hot die, or may be formed together inside and outside the hot die, and the kind thereof is not particularly limited. For example, a conventional electric heating element may be used.

Like the heating means, the cooling means may be formed only inside the low temperature die, or may be formed together inside and outside the low temperature die, and the kind thereof is not particularly limited, and for example, a pipeline through which a refrigerant flows. Cooling apparatuses, such as these, 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 point temperature of the hot die is less than 150 ° C., the extrudate may solidify slowly, and thus may not have a dense density, which may cause deformation of the extrudate and lower surface characteristics. On the other hand, when it exceeds 250 degreeC, since there exists a possibility that degradation of an extrusion raw material may occur, it is not preferable.

The temperature of the start point of the low temperature die can be appropriately adjusted according to the type of extrusion raw material, it is preferably maintained at a level slightly higher than the melting point or softening point of the extrusion raw material, more preferably, may be 40 to 150 ℃. If the starting temperature of the cold die 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 hot die decreases and the solidification of the extrudate is insufficient. This is because an additional relatively long vacuum cooler is required for the solidification.

However, even if the end point temperature of the hot die and the start point temperature of the cold die are determined in the above ranges, the temperature difference between them is 30 to 200 ° C. at a rapid temperature change rate of 2 to 40 ° C./mm, as defined above. It should be set to have.

The high temperature die and the low temperature die are preferably configured to be integrally included in one extrusion die. In this case, since the length of the temperature change section can be minimized, it is effective.

Further, the cold die may be one or more, for example, when the discharge rate of the melt is increased, it may include two or more cold die to increase the contact time of the cold die and the extrudate.

In the extrusion cooling system according to the present invention, the use of a vacuum cooler is not basically required, but in some cases, a short process length vacuum cooler may be selectively included between the extruder and the take-off. That is, it may be configured to selectively pass through a vacuum cooler when cooling and solidification are required in addition to the extrudate solidified in the low temperature die.

However, the vacuum cooler in the extrusion cooling system of the present invention is a device having a relatively short process length, for example, so as to significantly shorten the process length compared to a conventional vacuum cooling device, preferably 2 m or less It may have a process length of.

In one preferred example, it may be configured to further include a coolant circulator (chiller) for supplying the coolant to the vacuum cooler and / or cooling means. Therefore, cooling water is supplied by the cooling water circulator to circulate the refrigerant, thereby cooling the extrudate.

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.

The extrusion raw material is not particularly limited as long as it is an extrudable resin, preferably a thermoplastic resin or a thermoplastic resin-based composite, and may be plasticized by heating and melting in the extruder.

The thermoplastic resin is preferably acrylonitrile-butadiene-styrene (ABS) copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), polyester It may be one or two or more polymers selected from the group consisting of, polypropylene, and nylon, but is not limited thereto.

The extrudate according to the invention comprises unfoamed and foamed, and when the foam is produced using the extrusion cooling system according to the invention, it may preferably be 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 a foam having a dense density and similar mechanical properties to the non-foamed sheet. The contents of this application are incorporated herein by reference.

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 schematic diagram of a part of the extrusion die and vacuum cooling apparatus of the extrusion cooling system according to another embodiment of the present invention. .

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.

The end point temperature of the high temperature die 250 and the starting point temperature of the low temperature die 260 are set to have a temperature difference of 30 to 200 ° C at a rapid temperature change rate of 2 to 40 ° C / mm. That is, the internal heating means 220 of the high temperature die 250 and the cooling means 230 of the low temperature die 260 are installed at a very close distance, causing such a rapid temperature difference.

The molten plasticizer is taken out by the taker 40 while being made solidified when extruded from the extrusion die 200.

Optionally, if the extrudate requires further cooling and solidification, the extrudate passed through the cold die 260 can be passed through the vacuum chiller 300, where the vacuum chiller 300 is about 2 m. It can have a short process length below. Therefore, it is possible to prevent the waste of space, 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 detail by way of examples, but the scope of the present invention is not limited thereto.

[Examples 1 to 4]

An extrusion cooling system in which an extrusion die and an adapter in which a temperature-controllable hot die and a low-temperature die were integrally mounted was mounted on a twin screw extruder to prepare an extrusion cooling system. At this time, the length of the hot die was 125 mm, the length of the cold die was 40 mm, and the length of the temperature change section of the hot die and the cold die was 27 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, by using a high pressure pump, 2 parts by weight of nitrogen was injected into the barrel of the extruder to form a single phase mixture. To prepare a PVC sheet having a thickness of 2 mm, width 100 mm.

The conditions of the extruder were such that the sequential temperature of the barrels were 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

Except using the extrusion die formed by integrally controlling the hot die and the low temperature die, the conventional extrusion die composed of only the hot die was used, except that the cooling was performed by using a vacuum cooling device having a length of about 4 m. Then, a PVC sheet was manufactured in the same manner as in Example 1. 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%. . That is, since the vacuum cooling device is not used, it is possible to solve the spatial waste during extrusion and to improve the extrusion speed, thereby increasing the productivity significantly.

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 cooling system according to the present invention, the hot die and the cold die are continuously formed at the nozzle portion of the extruder, and the end point temperature of the hot die and the start point temperature of the cold die have a difference in a sharp temperature gradient. By constructing, it is not necessary to use a vacuum cooler to prevent space wastage, to reduce the cost of extrusion production, and to improve the extrusion speed can be obtained a very excellent effect in terms of production efficiency.

Claims (12)

It includes an extruder for plasticizing and extruding extruding raw materials, a take-off for taking the extruded molding at a predetermined speed, and a cutter for cutting the extruded molding to a predetermined length, and the nozzle portion of the extruder has a relatively hot die (" Hot die ") and relatively low die (" cold die ") are formed continuously, and the end point temperature of the hot die and the starting temperature of the cold die are 30 to 200 at a rapid temperature change rate of 2 to 40 DEG C / mm. An extrusion cooling system configured to have a temperature difference of 占 폚, wherein the extrudate is cooled and solidified at the same time as extrusion. The extrusion cooling system according to claim 1, wherein the length representing the temperature change rate is 1 to 150 mm. 2. The extrusion cooling according to claim 1, wherein a heating means for preventing a temperature drop is included at an end point of the hot die, and cooling means for preventing a temperature rise are included at a time point of the cold die. system. 4. The extrusion cooling system according to claim 3, wherein the heating means is an electric heating element, and the cooling means is a cooling device in which a refrigerant flows. 2. The extrusion cooling system according to claim 1, wherein the end point temperature of the hot die is 150 to 250 deg. The extrusion cooling system of claim 1 wherein the cold die temperature is from 40 to 150 ° C. 2. The extrusion cooling system according to claim 1, wherein the hot die and the cold die are integrally contained in one extrusion die. 2. The extrusion cooling system according to claim 1, wherein a vacuum cooler having a process length of 2 m or less is optionally included between the extruder and the take-off. 9. An extrusion cooling system according to claim 3 or 8, further comprising a coolant circulator for supplying cooling water to said cooling means and / or vacuum cooler. 2. The extrusion cooling system according to claim 1, wherein the extrusion raw material is a thermoplastic resin or a thermoplastic resin based composite, and is melted and plasticized by heating in the extruder. The extrusion cooling system of claim 1 wherein the extrudate is a fine foam. The method of claim 11, wherein the thermoplastic resin is acrylonitrile-butadiene-styrene (ABS) copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), Extrusion cooling system, characterized in that one or more polymers selected from the group consisting of polyester, polypropylene, and nylon.

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