JPS58225144A - Conductive resin composition for blow molding - Google Patents

Abstract

PURPOSE:To obtain titled composition with good blow moldability, capable of affording molded articles of high impact resistance, by incorporating a linear low-density polyethylene or a butyl rubber in a polyolefin resin containing a conductive carbon black to adjust so as to give a specific swelling ratio. CONSTITUTION:A conductive resin composition comprising (A) a polyolefin resin selected from high-density polyethylene, low-density polyethylene, and polypropylene and (B) a conductive carbon black is incorporated with (C) 5-50wt%, based on the final composition, of a linear low-density polyethylene or a butyl rubber to adjust the resulting swelling ratio a [a=b/2.095, where b is an extraded strand diameter (m/m)] to give a valve >=1.2 when measured under a load of 10kg. Said polyolefin resin is preferably a high-density polyethylene with a melt index 0.2-3.0g/10min.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive resin composition for blow molding and injection blow molding. Conductive resin compositions have come to be widely used as cases for parts of LSIs and ICs.

LSI and IC parts are destroyed when exposed to static electricity or radio wave interference during transportation or storage, so to avoid this, storage cases made of conductive resin compositions are often used.

On the other hand, injection molding has recently been replaced by blow molding for the purpose of reducing weight and saving material labor.

However, conductive resin compositions in which conductive carbon black is dispersed at a high concentration in low-density polyethylene (low-density polyethylene, high-density polyethylene, etc.) have poor stability in the parison produced during molding, and drawdown occurs, resulting in poor molding processability. Therefore, the obtained molded product also has uneven thickness and holes.

In addition, a considerable amount of carbon black was added to improve electrical conduction, which caused the overall molded product to become brittle. In particular, the hinge part (bending part) of the case needs to have good bending strength and flexibility.
Therefore, it was difficult to apply conventional methods to these blow molding processes.

In view of the above, the inventors of the present invention have conducted various studies in order to obtain a conductive resin composition that has good Brie molding processability and high impact resistance strength of molded products, and as a result, they have added conductive carbon black to polyolefin resin. Regarding the blended conductive resin composition, in the swelling ratio obtained using its melt index, a = 1.2 (a =
b/2.095 b; Extruded strand diameter (I
X) As a result of adding various resins, rubbers, etc., the addition of linear low density polyethylene (hereinafter referred to as L-LDPR) or butyl rubber results in a conductive product with excellent moldability and strength of the molded product. The present invention was achieved by discovering that it is possible to obtain a synthetic resin composition. That is, the present invention provides a conductive resin composition comprising one or more polyolefin resins selected from high-density polyethylene, low-density polyethylene, and polypropylene mixed with conductive case black. It is characterized by containing low-density polyethylene or butyl rubber so that the swelling ratio a (a = b / 2.095b; extruded strand diameter %) is 1.2 or more when measured under a 10 Kf load. This is a conductive resin composition for blow molding.

Among the high-density polyethylene, low-density polyethylene and polypropylene used in the present invention, particularly preferred is high-density polyethylene with a melt index and a mass of 0.2 to 3.0 (f/10 min).

In the present invention, the amount of L-LDPE added to the polyolefin resin for 9F is 5 to 50% by weight, preferably 5 to 30% by weight.

Furthermore, the butyl rubber used in the present invention has a specific gravity of 0.90.
y.

~0.92 and the viscosity average molecular weight is 40.000~3
50,000. Its blending amount is 5 in the composition.
-50% by weight, preferably 5-20% by weight.

Further, the conductive carbon black used in the present invention may be any one of furnace black, acetylene black, channel black, etc., and the amount thereof is 5 to 50% by weight in the composition, preferably 5 to 40% by weight. be.

In addition, in the present invention, in addition to the above-mentioned components, an ethylene-α olefin copolymer, an antioxidant, a lubricant, etc. may be added as necessary.

When blow molding is performed using the conductive resin composition of the present invention, the parison has good stability, no drawdown occurs, and the molding process can be performed under favorable conditions. Therefore, the overall strength of the molded product was high, and in particular, the hinge part maintained a predetermined constant thickness, and therefore the hinge stability was good.

The surface resistance of this molded product was 10 5 to 10 6 Ω, and the volume resistivity was 10 Ω α, making it suitable for practical use as a case for preventing static electricity.

On the other hand, when conventional conductive resin compositions are blow molded under the same conditions, the parison is unstable and drawdown occurs, resulting in holes and uneven thickness, resulting in poor molded products. I couldn't.

□ Hereinafter, the present invention will be specifically explained with reference to Examples.

The parts in Examples and Comparative Examples mean parts by weight.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 The formulations of the previous gH Examples and Comparative Examples were placed in a 704 Banbury mixer and heated at 180 to 200°C for 5 minutes. Knead. Next, this mixed wire material was subjected to a mixing roll at a temperature of 130 to 140°C and kneaded for 5 minutes to form a material with a thickness of about 2% and a width of about 3.
00% is drawn out into a plate shape, and this is made into square pellets using a square pelletizer.0 The square pellets are further heated to 90% e1 at a temperature of 180 to 200°C.
2.5-3.0% cylindrical pellets are obtained by extrusion using a vented extruder.

This cylindrical pellet was measured for 4 f as a measurement sample, and a melt indexer (temperature: 190°C, orifice diameter: 2.095°C) was measured.
After preheating for 5 minutes, extrude the strand with a load of 1 OI4.
The diameter of the 01 I understand that.

(1) In Examples 1 to 3 according to the present invention, the swelling ratios all showed a value of 1.2 or more, but in Comparative Examples 1 to 4
In all cases, the score was 1.2 or less.

Furthermore, blow molding machine (screw diameter 65%, L/1) ='
20, maximum parison diameter 100'X), and using the cylindrical pellets of Examples 1 to 3, Varisin 2 was molded through die 1 as shown in FIG. No phenomenon occurred, the diameter of Varisin 2 hardly changed, and no drawdown occurred.

On the other hand, when the cylindrical pellets of Comparative Examples 1 to 4 were passed through the die 1 to form a parison 2 in the same manner as described above as shown in FIG. 2, the diameter of the parison became tapered.
The occurrence of drawdown was confirmed. Furthermore, parison 2 had holes and uneven thickness.

In addition, using the cylindrical pellets of Examples 1 to 3 and Comparative Examples 1 to 40, molded products having a hinge part were molded using the same blow molding machine as described above, and the moldability of the hinge part was evaluated.
In other words, we conducted one observation to determine whether the thickness of the hinge part was molded to a desired constant thickness, or whether there were holes or uneven thickness in the hinge part, and it was found that Example 1
-3, as shown in Table 1, no holes or uneven thickness occurred, and the thickness of the hinge portion was also constant.

On the other hand, in Comparative Examples 1 to 4, as shown in Table 1, the thickness of the hinge portion was unstable, and the holes and uneven thickness were severe.

In Table 1, the mark ○ means that the moldability of the hinge part is good and no holes or uneven thickness are observed, the mark Δ means that uneven thickness has occurred, and the mark × indicates that there are holes. It means that the thickness and unevenness of the flesh are severe.

Table 1

[Brief explanation of drawings]

FIG. 1 shows a molded state of a parison according to the composition of the present invention, and FIG. 2 shows a molded state of a parison according to a comparative example. 1...Dice, 2...Parison Patent Applicant: Inunichisei Kakogyo Co., Ltd.

Claims (1)

[Claims] A conductive resin composition comprising one or more polyolefin resins selected from high-density polyethylene, low-density polyethylene, and polypropylene mixed with conductive carbon black, wherein the composition further includes linear low-density polyethylene or butyl rubber. A conductive material for blow molding, characterized in that the swelling ratio a (a=b/2.095 b; extruded strand diameter X) is 1.2 or more when measuring a 10# load. resin composition.