JPH072365B2 - Manufacturing method of plastic extruded material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a plastic extruded material such as a plastic pipe, a plastic rod, or a plastic coating for electric wires / cables.

[Prior Art] A plastic extruded material extruded from an extruder for a plastic pipe, a plastic rod, or an electric wire / cable is chilled by being cooled with cold water, or is gradually cooled with warm water of 100 ° C or lower and then cooled with cold water. The method of cooling was used. That is, as shown in FIG. 2, the plastic extruded material 2 extruded from the die 1 of the extruder is the cooling water ejection device.
In general, cooling water is sprinkled from 4a and 4b to quench the water. In some cases, the quench water spouting device 4a is sprinkled with hot water 5 ', and after slowly cooling, the cooling water spouting device 4b is cooled to cool water 5. It was hung and cooled.

[Problems to be Solved by the Invention] However, when the extruded material 2 is cooled with cold water or hot water of 100 ° C. or less as described above, when the extruded material is thick such as polyethylene, the extruded material is extruded. The temperature of the material is
At around 200 ° C., the cooling shrinkage due to this temperature difference was significant, and a cooling stripe pattern was formed on the surface of the extruded material after cooling, which was not desirable in appearance.

On the other hand, if the temperature of the extruder is lowered to reduce the temperature difference until cooling, the extruded material that is about to solidify in the vicinity of the extrusion surface is forced to be extruded or pulled, so that the surface becomes rough or torn and a good appearance is obtained. It was not possible to manufacture what has.

Further, in the above-described cooling using a liquid such as cooling water or warm water, the boundary of the temperature difference inevitably occurs in the portion where the liquid is applied, so that the generation of cooling stripes is unavoidable.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a plastic extruded material such as an electric wire / cable that has a good appearance without cooling stripes on the surface.

[Means for Solving the Problem] In the present invention, the extruded material extruded from the plastic extruder is first blown with a gas such as air to gradually cool the surface temperature to 100 to 130 ° C., and then 100 ° C. or less. This is a cooling method in which the hot water and the cold water are sequentially cooled.

[Operation] Therefore, the extruded material extruded from the plastic extruder is first gradually cooled by the gas without causing a boundary, and then cooled by the liquid of the hot water and the liquid of the cold water with the temperature difference being gradually reduced. It is possible to avoid the generation of cooling stripes caused by this.

[Embodiment] Hereinafter, the method of the present invention will be described with reference to the drawings. INDUSTRIAL APPLICABILITY The present invention can be applied to the production of all plastic extruded materials such as plastic pipes, plastic rods, or plastic coatings of electric wires / cables, but here, the case of plastic coatings of electric wires will be described. In FIG. 1, the covered electric wire 2 extruded from the die 1 of the plastic extruder is first cooled immediately after the die 1 by blowing gas from the air nozzle 3, for example, air. More specifically, the air 6 is blown to the surface of the covered electric wire 2 toward the side of hot water 5'to be described later and to the covered electric wire 2 at a predetermined angle with respect to the axial direction. As a result, the air 6 reaching the surface of the covered electric wire 2 evenly spreads to the portion cooled by the hot water 5 ', and effectively cools the covered electric wire 2 without causing a boundary. Next, cooling water jetting device
4a is cooled by applying warm water 5'of 100 ° C. or less, and then is cooled by applying cold water 5 from the cooling water jetting device 4b.

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

This is done by gradually cooling with a gas such as air,
This is because a boundary surface of a temperature difference such as liquid does not occur on the coating material. By this cooling, the coating material is cooled to a temperature of 100 to 130 ° C., and while being lowered from the temperature displacement point of the coating material, it is successively subjected to the following cooling by hot water of 90 ° C. and cold water of 15 ° C., for example. The difference in cooling shrinkage of the coating material is significantly smaller than that in the past, and no cooling stripes occur on the surface.

This is best if it can be naturally cooled in the air without blowing air or the like, but the extruded covered electric wire is a linear body, and since it is continuously extruded, it is necessary to support the covered electric wire. . Therefore, it is necessary to provide a fulcrum and sufficiently cool it before contacting it. This method is therefore impractical as it significantly increases the overall length of the device.

The extruded covering material is polyethylene and the outer diameter is 160 mm.
The appearance of the surface of the coated electric wire when a 13 mm-thick coating is formed on a φ linear body and cooled is shown in the following table.

In the above table, the appearance state is indicated by x when the cooling stripes are clearly formed, by Δ when the cooling stripes are formed, and by ○ when the cooling stripes are not formed.

[Effects of the Invention] As described above, in the present invention, a plastic extruded material extruded from a plastic extruder is first blown with a gas such as air to gradually cool the surface temperature to 100 to 130 ° C, and then hot water. In addition, since the cold water is cooled sequentially by the liquid by the liquid without causing a boundary, a clean appearance can be obtained without any cooling stripes on the extruded material. Further, it is economical to install a device for blowing a gas such as air without increasing the overall length of the device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a production method of an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing a conventional production method. 1 …… Extruder die 2 …… Coated electric wire 3 …… Air nozzle 4a …… Hot water jetting device 4b …… Cold water jetting device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsunetaro Sugaya 5-1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd. Hidaka factory (56) References Japanese Patent Laid-Open No. 20-20270 A) JP-A-61-293828 (JP, A)

Claims (1)

[Claims] 1. A surface of a plastic extruded material extruded from a plastic extruding machine, in which an air nozzle provided in the vicinity of the extruded material directs a gas such as air toward a hot water side described later and in an axial direction of the plastic extruded material. On the other hand, it is characterized in that it is sprayed at a predetermined angle, the surface temperature is gradually cooled to 100 to 130 ° C without causing a boundary, and then further cooled by using hot water and cold water of 100 ° C or less. Manufacturing method of plastic extruded material.