JPS6114241A - Conductive plastic - Google Patents

Abstract

PURPOSE:To obtain a conductive plastic having flexibility and excellent moldability by incorporating carbon black or graphite into a polymer component comprising a high-density PE, a linear low-density PE, and an EVA or an EPM. CONSTITUTION:Carbon black or graphite is incorporated into a polymer component comprising a high-density polyethylene (a), a linear, low-density polyethylene (b), and an ethylene-vinyl acetate copolymer (EVA) and/or a polymer containing an ethylene-propylene rubber (EPM) (c). A high-density polyethylene preferably of an extrusion grade is used since this composition is applied for covering a pipe using an extruder. A linear, low-density polyethylene, EVA, and EPR are used to give suitable flow characteristics of the compound based on a high-density polyethylene.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a conductive plastic that can prevent damage caused by electromagnetic waves entering from the outside by coating underground steel pipes. Out.

[Technical background]

Steel pipes have traditionally been used to house and protect electrical wires, communication cables, and the like.

In such cases, the surface of the steel pipe is usually coated with an anticorrosive coating such as polyethylene to prevent corrosion. The above-mentioned polyester used for anti-corrosion coating
Because the steel pipe exhibits a high insulation characteristic of io + 8 ohms, it floats at an intermediate potential, and electromagnetic waves generated externally pass through it, causing noise to the electric wires, communication cables, etc. housed inside. This has the inconvenience of causing so-called electromagnetic interference when it is transmitted to end equipment.

[Purpose of the invention]

The present invention is based on the fact that the steel pipe itself has good conductivity, and therefore external electromagnetic interference can be reduced by providing grounding between the steel pipe and the ground.

The purpose of this project is to maintain the corrosion prevention function of steel pipes while providing an electrical connection with the underground.

[Summary of the invention]

In order to achieve the above-mentioned purpose, various studies should be carried out.

This is because carbon black and graphite are blended into a polymer component consisting of ■high-density polyethylene, ■linear low-density polyethylene, and ■a polymer containing at least one selected from ethylene-vinyl acetate copolymer and ethylene-propylene rubber. This led to the creation of a conductive plastic.

It is preferable to use extrusion grade high-density polyethylene (hereinafter referred to as HDPE) using an extruder for the purpose of coating since the object to be used is a tube. Linear low-density polyethylene (LLDPE) is used to optimize the flow characteristics (MFR) of the compound based on HDPE.
), ethylene vinyl acetate copolymer (EVA), and ethylene propylene rubber (EPR).

The flow characteristics of the compound are, for example, 190℃, 10kg
When the load condition is 09~1.5L'3m, especially 1.0~
It is preferably set at 1.6g/3", and depending on the corresponding construction conditions, HDPE 18 to 35. LLDPE 56 to 7
0 and EVA or EPR from 10 to 20 (weight ratio).

In the present invention, LLDPE is mainly used to adjust flow characteristics.
EVA and EPR are expected to have flow characteristic adjustment and soft segment characteristics.

Carbon blank and graphite are blended with the polymer components described above, and the former is added to the compound at a weight ratio of 3 to 20. Preferably, the amount is 5 to 15 parts, and the latter is preferably 10 to 25 parts, preferably 10 to 20 parts. The reason for using two types of conductive materials is carbon black, which serves as an internal lubricant and to reduce costs.

Furthermore, the use of graphite is mainly intended to improve conductivity.

The conductive plastic (compound) prepared as described above is kneaded by a conventional method using a roll, kneader, etc. heated to about 150°C, and if it is kneaded by a roll, it is kneaded by a pelletizer, etc. After pelletization, molding or ejection, ``!*=-i-o!IFn (D 'jJ Otri
/y: ``The product is made into a product by hot-cutting it into pellets.

[Embodiments of the invention]

HDPE (Idemitsu Petrochemical System, product name 550p).

LLDPE (manufactured by Mitsui Petrochemicals, product name 2010DJ)
.

EVA (manufactured by Sumitomo Chemical, trade name R5[]1, 1 and 2)
01D) EPR (manufactured by Sumitomo Chemical, trade name 512F'),
Carbon black (manufactured by Lion Akzo, product name EC)
, graphite (manufactured by Tokai Carbon, 200 mesh under) was prepared, a compound was prepared according to the indicated compounding ratio, a sheet was formed from this compound, various properties were measured, and the results are also shown in the table. .

The polymer component, carbon black, and graphite were kneaded for 15 minutes using a pressure kneader (150°C), and the volume resistivity (δ, Ω・m) was kneaded at 150°C. A 3-spaced plate was formed using a held press, a test piece was cut out, and the voltage and current were read using the 4-terminal method.

Flow characteristics (MFR, g15”) are 190℃, 10kg
It shows the amount of ° at the load of , and also the tensile strength (TS).

Yu/cd) and elongation tests (E, Chi) were conducted using No. 1 dumbbells based on JIS.

[Effects of the Invention] The conductive plastic obtained according to the present invention uses plastic as the base material, so if it is used as a coating material, it can enjoy the effects of water resistance and corrosion resistance.
Furthermore, since this plastic is blended with a conductive material, it has conductivity with a volume resistivity of about 10Ω・α or less, is flexible and has good flow characteristics, so it has good moldability and excellent electromagnetic shielding properties. It becomes a coating material.

Note that since no metal is used as the conductive material, it is an inexpensive and lightweight material.

Claims (3)

[Claims] (1) High-density polyethylene, (2) Linear low density polyethylene and (3) A conductive plastic made by blending carbon black and graphite with a polymer component consisting of an ethylene vinyl acetate copolymer and a polymer containing at least one selected from ethylene/propylene rubber.