JPS6371330A - Manufacture of super high-molecular weight polyethylene pipe - Google Patents

Abstract

PURPOSE:To cool and solidify a pipe and form the pipe of superior mechanical strength by heat compressing molten super high-molecular weight polyethylene with a sizing die controlled at a fixed temperature, lowering the temperature gradually and adjusting the outer circumferential surface temperature of a formed pipe extruded out of the sizing die at most at a specified temperature. CONSTITUTION:Super high-molecular weight polyethylene is melted with a hydraulic plunger-type ram extruder setting, for instance, setting the temperature of heaters C1 and C2 of a cylinder 2 at 200 deg.C, the temperature of a heater D2 of a heating die at 220 deg.C, and the unevenness is adjusted by a bolt 14 of a sizing die 12. In order to lower the temperature of molten resin, whose unevenness has been adjusted, gradually from 220 deg.C, a heater D3 is set at 110 deg.C or lower, and a water-cooling jacket is used as a cooling machine 13, providing, for instance, a pipe of 95 deg.C of surface temperature at the outlet of a die. The pipe thus provided has a good external appearance and its mechanical strength is equivalent to that of a compression molded sheet.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing ultra-high molecular weight polyethylene pipes, such as pipe materials used as lining resin for resin lining rolls, pipe materials for resin rollers, The present invention relates to a method for manufacturing ultra-high molecular weight polyethylene pipes used as pipe materials for resin bearings or pipe materials for transporting slurry such as earth and sand.

(Conventional technology) Ultra-high molecular weight polyethylene with a molecular weight of 100 degrees or more has excellent properties such as impact resistance, abrasion resistance, self-lubricating properties, and chemical resistance, but compared to general-purpose thermoplastic resins Since it has an extremely high melt viscosity and poor fluidity, it is extremely difficult to mold it by conventional screw extrusion molding or injection molding. For this reason, pipes are generally formed by compression molding, but this forming method cannot be applied when continuously forming pipes, so conventionally known methods include extrusion molding using a ram extruder equipped with a mandrel. . An extrusion molding method using a screw extruder using a special molding die has also been proposed.

(Problems to be Solved by the Invention) However, when molding is performed using a ram extruder equipped with a mandrel, the accuracy of pipe thickness deviation is poor, and the linearity in the center direction is also poor.

Furthermore, it has the disadvantage that it is difficult to form a pipe with an inner diameter of φ10w or less.

On the other hand, molding using a screw extruder has the disadvantage that the extruded pipe has a reduced mechanical strength because the molten ultra-high molecular weight polyethylene is subjected to shear stress by the screw, causing molecular chains to break and the molecular weight to decrease.

The present invention aims to improve these points and provide a method for forming a pipe with good thickness unevenness accuracy and excellent mechanical strength.

(Means for solving the problem) Using a ram extruder equipped with a pipe-forming gou consisting of a sizing die capable of uneven thickness cleavage via a spider gou and a mandrel inserted and fixed into the heating gou. In a method for manufacturing an ultra-high molecular weight polyethylene vibrator, ultra-high molecular weight polyethylene heated and melted in a ram extruder is heated and compressed using a sizing die whose temperature is controlled to a predetermined temperature, and thickness unevenness is adjusted. The present invention provides a method for producing an ultra-high molecular weight polyethylene pipe, in which the temperature is gradually lowered toward 100° C. or less, and the temperature of the outer circumferential surface of the formed pipe extruded from a sizing die is adjusted to 100° C. or less, and the pipe is cooled and solidified.

Next, a ram extruder used in the production method of the present invention will be explained. First, the ram extruder (1) shown in FIG.
), a ram (3) reciprocating within the cylinder (2);
It consists of a raw material supply section (4) and a gooey attachment flange (5). The pipe forming die (6) attached to this ram extruder (1) has a mounting flange (7) for connecting and fixing the pipe forming guide (6) to the ram extruder +1) as shown in Fig. 2. , a heating die (8) for controlling the temperature of the ultra-high molecular weight polyethylene resin heated and melted in the ram extruder using a heater (Dl), and a spider die (9) for regulating the inner diameter of the pipe and supporting the mandrel 011.
), and a sizing die (2) for compressing and fusing the molten resin separated by the spider α and forming it into a pipe shape.

The above sizing die (■) is equipped with a heater (D3) on the spider die (9) side and a cooler (p) on the resin outlet side, and allows for uneven thickness adjustment by slightly moving the sizing die (+2) with the bolt (14). There is.

Next, we will explain a method for manufacturing ultra-high molecular weight polyethylene vibes using the ram extruder (1) equipped with the pipe-forming die (6). 3 million or more, or 1 million or more according to the viscosity method, such as Hoechst's Ho
5talen GUR.

Mitsui Petrochemical Industries - Hize Million
x Million), and formulations containing various additives can also be used.

First, ultra-high molecular weight polyethylene powder is supplied to the raw material supply section (4
) and the temperature of cylinder (2) is 150-25
After the temperature is adjusted to a temperature range of 0° C., the heated and molten state is extruded by the ram (3) toward the pipe-forming die (6).

The resin heated and melted in this way is heated to a temperature of 150°C to 250°C by a heater (DI).
8) Pass through the spider die (9) spider a
The resin separated by the spider α is compressed into a pipe shape while reducing its diameter at the entrance of the sizing die (2). In this case, unlike melts of general-purpose resins, ultra-high molecular weight polyethylene has a high melt viscosity (it must be heated and compressed between the spider die (9) and the sizing die (■) to erase the spider marks caused by the spider die (9). be.

This heating temperature is adjusted with a heater (D2) and is usually 150
~250°C, the compression ratio is 1.1 to 5.0, preferably 1
．． It is in the range of 3 to 3.0. If compression is insufficient, the melt will not be sufficiently fused, leaving spider marks or, in extreme cases, not being formed into a pipe shape, and if compression is excessive, extrusion will not be possible. The uneven wall thickness of the pipe is made by adjusting the position of the sizing die ① (by adjusting the position of the bolt).

The above compression ratio is the ratio of the cross-sectional area Sl of the resin flow path at the connection part of the spider ○ to the resin flow in the sizing die (■), that is, 31/S2.

In addition, the resin compressed into a pipe shape at the entrance of the sizing die ■ enters the sizing die ■ whose temperature is controlled at 150 to 250℃ on the spider side, but if this temperature exceeds 250℃, thermal deterioration of the resin will occur. Moreover, the temperature difference between the outlet side and the cooled outlet side becomes extremely large, which is not preferable because the resin is rapidly cooled and internal stress remains.

On the other hand, if the sizing die temperature on the spider side is lowered to less than 150°C, insufficient fusion will occur.

The resin thus formed into a pipe shape passes through a sizing die (2) having a constant diameter and is extruded out of the die. The ratio of the inner diameter of F], that is, L/
It is preferable that D is 5 or more; if it is less than 5, the resin will be insufficiently fused, and if it exceeds 20, the pressure inside the die will be undesirably excessive.

Heater (D3), cooler (1 m is for fusing the ultra-high molecular weight polyethylene in the sizing die, and then sequentially lowering the temperature to bring the pipe surface temperature at the die outlet to 110°C or less. .

The mandrel α1) is used to regulate the inner diameter of the pipe, and if it is made longer than the sizing die and its tip extends outside the die, the tip of the extruded pipe will not get caught inside, and the extrusion direction of the pipe will be adjusted to the sizing die. This is preferable because it is pressed along the center line.

(Example) Ultra-high molecular weight polyethylene (trade name: ) (ostaten
GUR412, manufactured by Hoechst) in the cylinder (2)
The temperature of the heaters (C+, C2) of the heating die is set to 200℃, and the temperature of the heater (D2) of the heating die is set to 220℃. Adjust. The temperature of the molten resin with uneven thickness is gradually lowered from 220°C.
The heater (D3) is set at 130°C, and a water cooling jacket is used as a cooler (total) to keep the surface temperature at the die outlet to 95°C.
C pipe was obtained. The obtained pipe dimensions are outer diameter φ22
゜Ofl, inner diameter φ8.6, thickness deviation accuracy is 6.7±0゜1
m, the appearance is good, and the mechanical strength is as shown in the table.
It was equivalent to a compression molded plate.

(Effects of the Invention) As described above, the method of the present invention involves heating and melting ultra-high molecular weight polyethylene in a ram extruder to a temperature range of 150 to 250°C, and then melting the ultra-high molecular weight polyethylene using a sizing die in which the temperature of the spider and the spider side is controlled at 150 to 250°C. The pipe is heated and compressed at the same time as the uneven thickness is adjusted, and then the temperature is gradually lowered to bring the outer surface temperature of the pipe to 1.
It is a material that solidifies by cooling to 10 degrees Celsius or below, which allows pipes with good thickness unevenness and excellent mechanical strength to be formed.It is also possible to form pipes with an inner diameter of φlOn or less, and is a pipe material used as a lining resin. Alternatively, it is possible to manufacture an ultra-high molecular weight polyethylene pipe that is passed through a pipe material for transporting earth and sand slurry.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a ram extruder used in the manufacturing method of the present invention, FIG. 2 is a sectional view of a pipe-forming die, and FIG. 3 is a sectional view taken along line AA in FIG. (11... Ram extruder (6)... Pipe forming die (8)... Heating die (9)... Spider die aΦ... Spider (10... Mandrel ■...
Sizing die patent applicant Mitsuboshi Belting Co., Ltd. Figure 3 procedural amendment (voluntary) May 5, 1988

Claims (1)

[Claims] 1. Manufacture ultra-high molecular weight polyethylene pipes using a ram extruder equipped with a pipe-forming die consisting of a sizing die that can adjust thickness unevenness through a spider die and a mandrel inserted and fixed into the heating die. In this method, ultra-high molecular weight polyethylene heated and melted in a ram extruder is heated and compressed in a sizing die controlled to a predetermined temperature, and uneven thickness is adjusted, and then the temperature is gradually lowered toward the tip of the sizing die. 1. A method for producing an ultra-high molecular weight polyethylene pipe, characterized in that the outer peripheral surface of a molded pipe extruded from a sizing die is adjusted to 110° C. or lower, and the pipe is cooled and solidified.