JPS5932494B2 - Conductive resin composition - Google Patents

Description

Detailed Description of the Invention The present invention uses styrene in addition to polystyrene as the resin component.
The present invention relates to a conductive resin composition containing an isoprene-styrene block copolymer, and particularly to a conductive resin composition that has excellent moldability and good mechanical properties such as impact strength and bending strength.

In recent years, conductive resin compositions have been widely used as materials for antistatic cases, such as cases for industrial C parts.

Since IC parts break when exposed to static electricity during transportation or storage, they must be stored in a case made of a conductive resin composition to prevent static electricity. Conventionally, a resin composition prepared by adding and mixing conductive carbon black to a styrene resin has been used as the conductive resin composition.

However, although such conductive resin compositions maintain the desired conductivity, they are not only inferior in moldability but also inferior in mechanical properties such as impact strength and bending strength, and are not preferred in practice. In particular, IC cases require long molded products by profile extrusion, and for this reason, the conductive resin composition used for this molding has particularly excellent moldability and mechanical properties. This is strongly desired. An object of the present invention is to provide a conductive resin composition which has excellent moldability and mechanical properties, and which has improved the drawbacks of the prior art.

In order to achieve the above object, according to the present invention, in a conductive resin composition containing polystyrene and conductive carbon black, a styrene-isoprene-styrene block copolymer is further added to the composition based on the total composition weight. 5～
It is characterized by containing 90% by weight.

Hereinafter, the present invention will be specifically explained in detail.

The polystine used in the present invention may be of any type, and one example is the high-impact polystyrene resin "Styron 470" manufactured by Asahi Tau Co., Ltd., and the amount used can also be any suitable amount.

As the conductive carbon black used in the present invention, various carbon blacks having conductivity can also be used,
Specifically, Furness Black, Acetylene Black,
Examples of the product names include carbon black "Ketschen Black EC" manufactured by Lion Corporation and carbon black "Denka Black" manufactured by Denki Kagaku Kogyo Co., Ltd..

This amount has good conductivity (VR value is 10-107Ωc).
m) from 5 to 60% by weight of the total composition weight to retain
Preferably it is 5 to 40% by weight. Furthermore, the styrene-isoprene-styrene block copolymer used in the present invention includes, for example, SIS thermoplastic elastomer "Califlex TR-1107" manufactured by Shinil Kagaku Co., Ltd., and the amount used is 5 to 50% of the total weight of the composition. The amount is 90% by weight, preferably 10-60% by weight.

The amount used is less than 5% by weight, or 9% by weight.
If the amount is greater than 0% by weight, the resulting composition will not be able to exhibit good moldability or excellent mechanical properties, which is undesirable. The composition of the present invention contains the above-mentioned three components as essential components, and in particular, the greatest effect lies in containing a predetermined amount of styrene-isoprene-styrene block copolymer for the two components of polystyrene and conductive carbon black. It is manufactured by thoroughly mixing the three components described above using a conventionally known mixing method, for example, using a Banbury mixer, a kneader, an extruder, a double roll, etc., and forming the mixture into pellets.

In addition to the above-mentioned three components, the composition of the present invention may contain other components, such as antioxidants, heat stabilizers, lubricants, etc., in any appropriate amounts as necessary.

The composition of the present invention produced in this way has little deformation even when subjected to profile extrusion molding, has a smooth surface, and can be manufactured into long products, and therefore has excellent moldability and the molded product obtained. It has high impact strength and bending strength, and therefore has good mechanical properties.

Further, even when the composition of the present invention is injection molded, there are few so-called flow marks, and molded products with complicated shapes can be obtained. Hereinafter, the present invention will be explained in further detail with reference to Examples.

Example 1 As shown in Tables 1 and 2, predetermined amounts of various ingredients were thoroughly kneaded in a Banbury mixer, formed into a sheet using two rolls, and then pelletized in a square pelletizer to form sample JKl. ~11 was obtained.

In addition, each sample in Table 1 (Samples 1 to 6) is a composition according to the present invention, and each sample in Table 2 (Samples 7 to 11) does not use a styrene-isoprene-styrene block copolymer. It is a conventional composition. Styron 470: Asahi Tau high impact polystyrene resin star rack≠20
0: ABS resin Sunrex C manufactured by Asahi Tau Co., Ltd.; AS resin Butt Envelope Black EC manufactured by Mitsubishi Monsanto Chemical Co., Ltd.; Carbon Black Denka Black manufactured by Lion Corporation; Carbon Black Califlex TR-1107 manufactured by Denki Kagaku Kogyo Co., Ltd.;
SIS thermoplastic elastomer manufactured by Ciel Chemical Co., Ltd. Evaluation tests regarding extrusion moldability and mechanical properties were conducted on each of the samples described above, and the results are shown in Table 3.

Evaluation of extrusion moldability is from 30 to non-vent extruder and 5C
Tt×1m77! A belt extrusion die was used, and the extrusion stability, appearance of the molded product, and dimensional stability were comprehensively evaluated.

In Table 3, the mark ◎ indicates "very good", the mark ○ indicates "good", and the mark x indicates "poor". Mechanical properties were evaluated by measuring the impact strength and bending strength of the molded product.

The impact strength was evaluated by the degree of cracking of the molded product when the molded product was cut into a predetermined length with a cutter during the molding process of the long product. In Table 3, the mark ◎ means "no cracking at all", the mark O means "almost no cracking", the mark △ means "slightly cracking", and the mark X means "completely cracking". In addition, the bending strength of the molded product is 20C.
It was cut to the length of TL and evaluated by the degree of cracking when stress such as bending and twisting was applied. In Table 3, the O mark indicates "almost no cracking" and the x mark indicates "completely cracking". From Table 3, samples 1 to 6 of the composition of the present invention show good values for extrusion moldability, impact strength, and bending strength, but
Conventional compositions that do not use styrene-isoprene-styrene block copolymers (samples black 7 to 11) do not have any of the above-mentioned values. It can be seen that both the mechanical properties and the mechanical properties are excellent.

Example 2 Samples 12 to 17 were obtained in the same manner as in Example 1 by blending various components in predetermined amounts as shown in Table 4.

Each of these samples was evaluated in terms of extrusion moldability and mechanical properties in the same manner as in Example 1, and the results are shown in Table 5. Table 1 shows that the composition of the present invention exhibits good extrusion moldability and mechanical properties when the amount of the styrene-isoprene-styrene block copolymer is in the range of 5 to 90% by weight. The amount of styrene-isoprene-styrene block copolymer is 5 to 90% by weight.
It can be seen that the range is within the range of .

Claims (1)

[Claims] 1. A conductive resin composition containing polystyrene and conductive carbon black, which further contains 5 to 90% by weight of a styrene-isoprene-styrene block copolymer based on the total composition weight, and has excellent moldability. and a conductive resin composition with good mechanical properties.