JPH04201536A - Multi-stage apparatus for extruding molten resin - Google Patents

Abstract

PURPOSE:To speedily cool molten resin within respective resin pipes by constituting time apparatus wherein molten resin extruded from a first extruder is dividingly flowed into a plurality of resin pipes, and then cooled by coolant that runs in the outside of respective resin pipes. CONSTITUTION:Molten resin D extruded from the extruding port G of a first extruder A is dividingly flowed into a plurality of resin pipes 3 provided in a transferring pipe K. For this reason, the cross-sectional area of molten resin running in respective resin pipe 3 is small, and thus the flow rate thereof is also small. Furthermore, since coolant passages S formed outside respective resin pipes 3 are led, molten resin D in respective resin pipe 3 is cooled promptly without causing the dispersion of temperature. Moreover, coolant S flowing in cooling passages 4 is changed forcibly in its flowing direction by partitions 5 and coolant passageways 6 formed thereon, as a result, it is not likely to become stagnant, and thereby molten resin D in all resin pipes 3 is cooled at nearly uniform temperature.

Description

[Detailed description of the invention] [Industrial application field]

The multi-stage molten resin extrusion apparatus of the present invention is used, for example, to extrude and coat the outer periphery of a core wire with resin during the production of crosslinked polyethylene insulated cables.

[Conventional technology]

Conventionally, when manufacturing a crosslinked polyethylene insulated cable, for example, the following method is used. As shown in Fig. 4, the pellet-shaped resin material C supplied to the hopper B of the first extrusion mA is heated to an appropriate temperature and melted, and an anti-aging agent E with a melting point of 170°C is added to the molten resin.
This molten resin is passed through the screen pack J set on the breaker plate H on the side of the extrusion port G to remove foreign substances mixed in the molten resin. Remove. At this time, if the temperature of the molten resin is low, the anti-aging agent E will not melt sufficiently, so the anti-aging agent E cannot be uniformly kneaded into the molten resin. Since the mesh is as fine as 100 to 500, the resistance when passing through the screen pack J made of molten resin is large, and if the temperature becomes extremely low, there is a risk that the screen pack J will be torn due to the resistance. Therefore, the temperature of the melt @resin in the first extrusion 41A is usually about 17
It is set to a high temperature of about 0°C. This molten resin is supplied to the supply port M of the second extruder 11L through the transfer pipe shown in FIG. be included. It is then supplied to a crosshead P, where the outer periphery of the core wire Q is coated by extrusion, thereby completing a crosslinked polyethylene insulated cable. At this time, if the temperature of the molten resin remains at about 170°C, the molten resin is likely to burn when the crosslinking agent N is injected, so the molten resin is not supplied to the second extruder. n
It is necessary to lower the temperature of the molten resin to below about 135° C. before it is heated. Therefore, conventionally, as shown in Fig. 4, a heat exchange medium (refrigerant) S is passed through a refrigerant passage R provided on the outer periphery of the transfer pipe through which the molten resin passes, and the entire molten resin is extruded. was forcibly cooled from the outside. By the way, the resin without the crosslinking agent has a temperature of 170°C.
Although there is no need to worry about burning, the molten resin becomes too soft and it becomes difficult to extrude and coat the outer periphery of the core wire with a uniform thickness, which tends to cause uneven thickness.

[Problem to be solved by the invention]

However, in the conventional extrusion l#Lm method, the refrigerant passage S is provided only at the outermost periphery of the transfer pipe, so that the molten resin passing through the center of the transfer pipe is sufficiently cooled. The temperature of the refrigerant S must be lowered considerably, but there is a problem in that if the temperature is lowered too much, the molten resin DtJS in the outer portion of the transfer pipe will solidify. To solve this difficult problem, set the temperature of refrigerant S relatively high,
The length of the transfer pipe may be increased so that the molten resin is gradually cooled by the refrigerant S while passing through the pipe. However, doing so poses the problem of increasing the size of the entire multi-stage molten resin extrusion device.

[Purpose of the invention]

It is an object of the present invention to provide a multi-stage molten resin extrusion system that can quickly cool the melted resin to a uniform temperature by eliminating variations in the temperature of the melted resin in the transfer pipe to be cooled, and that can reduce the size of the entire device. The goal is to provide equipment.

[Means to solve the problem]

As shown in FIGS. 1 to 3, the multistage molten resin extrusion apparatus of the present invention is configured to transfer molten resin extruded from a first extruder A to a second extruder through a transfer pipe K. In the multi-stage molten resin extrusion apparatus, a plurality of resin pipes 3 are arranged in the transfer pipe, through which the molten resin extruded from the first extruder A branches, and each of the resins is A refrigerant passage 4 through which the refrigerant S flows is formed on the outside of the conduit 3, and two or more partition plates 5 are provided in the refrigerant passage 4, in which a part thereof is provided with a refrigerant passage port 6 through which the refrigerant S passes, It is characterized in that the positions of the refrigerant passage ports 6 of the partition plates 5 are shifted so that the direction of flow of the refrigerant S is changed.

[Effect]

In the multi-stage molten resin extrusion device of the present invention, as shown in FIGS. Since the flow is divided into the resin pipes 3, the film area of the molten resin flowing inside each resin pipe 3 is small, the device is also small, and the refrigerant flows into the refrigerant flow path 4 formed outside each resin pipe 3. Since the refrigerant S is flowing, the temperature of the molten resin in each resin pipe line 3 does not vary (it is quickly cooled down. Since the flow direction is forcibly changed by the refrigerant passage port 6 formed therein, stagnation does not easily occur, and the molten resin in all the resin pipes 3 is cooled to a substantially uniform temperature.

[Example] Figures 1 to 3 show an example of a multi-stage molten resin extrusion apparatus of the present invention. In Fig. 1, A is the first extruder, B is the hopper of the extruder A, C is the pelletized resin material supplied to the hopper B, D is the melted resin that has been melted and kneaded, and F is the hopper of the extruder A. - Screw in extruder A, G is the extrusion port of extruder A, H is the breaker provided on the interpolation port G side, plate J is the screen back set on the same breaker plate H, E
T is an anti-aging agent to be kneaded into the molten resin, and T is a pump for supplying the anti-aging agent E. In addition, L is the second extruder, M is the supply port 9N of the same extruder, and the extruder 11 is
The crosslinking agent injected into L, U is the pump for injecting the same crosslinking agent N, P is the crosshead to which the molten resin extruded from the same extrusion $1L is supplied, and Q is covered with the same molten resin. This is the core wire. These may be existing ones or ones improved for the present invention. K shown in FIGS. 1 to 3 connects the first extruder A and the second extruder iL, and transfers the molten resin extruded from the extrusion port G of the first extruder A to the second extruder This is a transfer pipe line for transferring to the supply port M of the extrusion 41L. A refrigerant supply pipe 10 and a refrigerant discharge pipe 11 connected to a refrigerant circulation device 12 are attached to this transfer pipe K, and as shown in FIGS. One closing plate 1 is attached to the outside of the refrigerant discharge pipe 1, and the other closing plate 2 is attached to the outside of the refrigerant discharge pipe 1.
is installed. Reference numeral 3 shown in FIGS. 2 and 3 indicates a plurality of resin pipes which are passed through between the two closing plates 1 and 2, and this is where the molten resin extruded into the transfer pipes flows. It branches and flows. As this resin conduit 3, a pipe or the like having an inner diameter of about 1/3 to 1150 of the inner diameter of the cylinder of the extruder and a wall thickness of about 1/3 to 1150 of the inner diameter of the cylinder of the extruder is used. 3 metal pipes of 12 mm and 2 ROM wall thickness
One in the center of the transfer pipe, six around it (second row), and 12 around it (third row).
, 18 pieces (fourth row) were arranged concentrically and equally spaced around it. 4 shown in FIGS. 2 and 3 is a refrigerant flow path formed outside the resin pipe 3, specifically between the outer periphery of the resin pipe 3 and the inner periphery of the transfer pipe. is formed. This is for cooling the molten resin passing through the resin conduit 3 through the flow of the refrigerant S supplied from the refrigerant supply pipe IO. The refrigerant S is discharged from the refrigerant discharge pipe 11. Reference numeral 5 shown in FIGS. 2 and 3 indicates two or more partition plates provided within the refrigerant flow path 4. A refrigerant passage port 6 through which the refrigerant S passes is formed in a part of the partition plate 5 . These partition plates 5 are installed with the positions of the refrigerant passage ports 6 shifted so that the flow direction of the refrigerant S changes as shown in FIG. The temperature of the molten resin in the resin conduit 3 of each row was compared between the multi-stage molten resin extrusion apparatus of this example and the multi-stage molten resin extrusion apparatus without the partition plate, and is shown in the table below. As is clear from this table, in the extrusion apparatus of the present invention, there is little variation in the temperature of the R8 melt resin in the resin pipe lines 3 of each row, and the resin is cooled to a nearly uniform temperature. In this embodiment, only the case where the molten resin is cooled will be described in detail, but the multi-stage molten resin extrusion apparatus of the present invention cools the molten resin extruded from the first extruder A, for example. It can also be used to add force before being supplied to the extruder, and in that case, a heating medium may be used as a heat exchange medium instead of the refrigerant S, and its use is particularly limited. isn't it.

【Effect of the invention】

In the multi-stage molten resin extrusion apparatus of the present invention, the first extrusion 11
The molten resin extruded from A is divided into a plurality of resin pipes 3, and is cooled by the refrigerant S flowing outside each resin pipe 3, so that the molten resin in each resin pipe 3 is is rapidly cooled down. Moreover, the flow direction of the refrigerant S can be changed by the partition plate 5 and the refrigerant passage port 6 without stagnation.
The molten resin in all the resin pipes 3 is cooled to a substantially uniform temperature. Therefore, the length of the transfer pipe can be shortened, and the entire multistage molten resin extrusion apparatus can be downsized.

[Brief explanation of the drawing]

FIG. 1 is an overall structural diagram showing an embodiment of the multi-stage molten resin extrusion device of the present invention, FIG. 2 is a partial cross-sectional perspective view of the transfer pipe section of the same device, and FIG. FIG. 4 is an overall structural diagram showing an example of a conventional multi-stage molten resin extrusion device. 3 is a resin pipe line 4 is a medium flow path (refrigerant flow path) 5 is a partition plate 6 is a medium passage port (refrigerant passage port) A is the first extruder, the molten resin is transferred to the second transfer pipe Extruder S is a heat exchange medium (refrigerant) Fig. 2

Claims (1)

[Claims] In a multi-stage molten resin extrusion device in which molten resin extruded from a first extruder is transferred to a second extruder through a transfer pipe, the molten resin extruded from the first extruder is transferred into the transfer pipe. A plurality of resin pipes are arranged in which the molten resin branches and flows, and a medium flow path through which a heat exchange medium flows is formed on the outside of each resin pipe. A multistage device characterized by having two or more partition plates provided with medium passage ports through which the medium passes, the positions of the medium passage ports of the partition plates being shifted so that the flow direction of the heat exchange medium changes. Type molten resin extrusion equipment.