JPH01150519A - Method for manufacturing plastic extrusion member - Google Patents

Abstract

PURPOSE:To obtain a plastic extrusion member without any cooling stripes on its surface and with an excellent appearance by cooling slowly the surface temperature of an extrusion member extruded from a plastic extruder in spraying gas such as air or the like at first to specific temperature, after that, by cooling it gradually in use of warm water and cold water below the specific temperature. CONSTITUTION:A covered electric wire extruded from a die 1 is cooled at first by spraying gas, for instance, air from an air nozzle 3 right behind a die 1. Subsequently, it is cooled by pouring warm water 5' below 100 deg.C from a cooling water spouting device 4a and then cooled by pouring cold water 5 from a cooling water spouting device 4b. This is aimed to prevent the boundary surface of temperature difference such as liquid from generating on a covering member by slowly cooling it at first through gas such as air or the like. By this cooling, the cooling member is cooled at temperature of 100-130 deg.C and subject to be cooled consequently, under the condition lower than the temperature displacement point of the covering member, for instance, by next warm water of 90 deg.C and cold water of 15 deg.C, so that the contraction difference of the covering member becomes considerably low and the generating of cooling stripes does not occur thereupon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing plastic extruded materials such as plastic pipes, plastic rods, or plastic coatings for electric wires and cables.

[Prior Art] Plastic extruded materials extruded from an extruder for plastic pipes, plastic rods, or electric wires/cables are quenched by being poured with cold water, or slowly cooled with hot water of 100°C or less, and then poured with cold water. A cooling method was used. That is, as shown in FIG.
The extruded plastic material 2 is generally quenched by being sprayed with cooling water from the cooling water spouting devices 4a and 4b, and in some cases hot water 5' is sprayed from the cooling water spouting device 4a to cool it slowly. After cooling, cold water 5 was sprayed from a cooling water jetting device 4b to cool the vehicle.

[Problems to be Solved by the Invention] By the way, when the extruded material 2 is cooled with cold water or hot water of 100°C or less, if the extruded material is thick, such as polyethylene, the extruded material The temperature is around 200℃, and cooling shrinkage due to this temperature difference is significant, so cooling stripes appear on the surface of the extruded material after cooling.
I didn't like the appearance.

On the other hand, if the temperature of the extruder is lowered in an attempt to reduce the temperature difference during cooling, the extruded material that is about to solidify near the extrusion surface is forced out or pulled, causing the surface to become rough or torn, resulting in a poor appearance. It has not been possible to manufacture something with this.

Furthermore, in the case of cooling using liquid such as cooling water or hot water as described above, a boundary of temperature difference inevitably occurs in the area where the liquid is applied, so the occurrence of cooling rings is unavoidable.

The present invention has been made in view of these points, and an object of the present invention is to provide a plastic extrusion material, such as an electric wire or cable, which has a good appearance and has no cooling ring on its surface.

[Means for solving the problem] In this A), the extruded material extruded from a plastic extruder is first slowly cooled to a surface temperature of 100 to 130°C by blowing a gas such as air, and then This is a cooling method in which hot water and cold water of 100° C. or lower are used to sequentially cool the product.

[Function] Therefore, the extruded material extruded from a plastic extruder is first slowly cooled by gas without creating a boundary, and then cooled by hot water and cold water by sequentially reducing the temperature difference. The generation of cooling rings caused by temperature differences can be avoided.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention can be applied to the production of all plastic extruded materials such as plastic pipes, plastic rods, and plastic coatings for electric wires and cables.Here, the case of Plastilaf coating for electric wires will be explained. In FIG. 1, a covered wire 2 extruded from a die 1 of a plastic extruder is first cooled by blowing gas, for example air, from an air nozzle 3 immediately after the die 1. Next, hot water 5' of 100'c or less is applied from the cooling water jetting device 4a to cool it, and then cold water 5 from the cooling water jetting device 4b is applied to cool it.

That is, the covered electric wire 2 extruded by a plastic extruder
First, the coating material is slowly cooled with air, and then the coating material is sequentially cooled with hot water and then with cold water so as not to cause a significant temperature difference in the coating material.

This is done by first slowly cooling with a gas such as air.
This is to prevent temperature differences such as those in liquids from occurring at the interface or at the coating material. This cooling reduces the coating material to 100 to 13
After being cooled to a temperature of 0°C, the temperature is lowered below the temperature displacement point circle of the sheathing material, and then it is sequentially cooled with, for example, 90°C hot water and 15°C cold water, so the difference in cooling shrinkage of the sheathing material is It will be significantly smaller than the previous one,
No cooling ring occurs on its surface.

This is best if it is allowed to cool naturally in the air without blowing air, etc. However, since the extruded covered wire is a linear body and it is extruded continuously, it is necessary to support the covered wire. There is. Therefore, it is necessary to provide a fulcrum and sufficiently cool it before coming into contact with it. This method is not practical as it significantly increases the overall length of the device.

The extruded covering material is polyethylene and has an outer diameter of 160 mm.
The following table summarizes the appearance of the surface of the coated wire when a 13 mm thick coating is formed on a mmφ wire body and the coat is cooled.

In the above table, the appearance condition is marked as "X" if the cooling ring or FJ1 is clearly formed, "△" if the cooling ring is formed, or "○" if there are no cooling stripes.

[Effects of the Invention] As explained above, in this invention, the plastic extruded material extruded from the plastic extruder is first slowly cooled to a surface temperature of 100 to 130°C by blowing a gas such as air, and then heated with hot water. Since the extruded material is cooled by a liquid containing cold water, no cooling ring is generated on the extruded material, and a product with a clean appearance can be obtained. Furthermore, it is economical to add a device for blowing gas such as air without increasing the overall length of the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a manufacturing method according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a conventional manufacturing method. 1... Extruder tie 2... Covered electric wire 3... Air nozzle 4a... Hot water jetting device 4b... Cold water jetting device

Claims (1)

[Claims] The plastic extruded material extruded from the plastic extruder is first blown with a gas such as air to bring the surface temperature to 100-1
1. A method for producing a plastic extruded material, which comprises slowly cooling the material to 30° C. and then cooling it using hot water and cold water of 100° C. or lower.