JPS58108242A - Electrically conductive resin composition - Google Patents

Abstract

PURPOSE:To prepare a composition having excellent dimensional accuracy, high electric conductivity, and extremely good heat resistance, rigidity, impact resistance and moldability, by compounding a specific propylene polymer with a specific talc and carbon black. CONSTITUTION:The objective composition is prepared by compounding (A) a propylene polymer resin or a composition of the resin with a synthetic rubber, containing 10-50wt% component extractable with xylene at 23 deg.C wherein the propylene content in the extractable component is >=30%, with (B) talk having an average particle diameter of 0.5-20mu determined by the light transmission using a liquid-phase sedimentation method, and (C) carbon black. The ratio of (A)/(A)+(B) is 25-90%, (B)/(A)+(B) is 75-10%, and (C)/(A)+(B) is 2-100%. Preferably the component (A) is crystalline propylene-ethylene block copolymer, the component (B) is talc having an impurity content of <=0.9%, and the component (C) is SCF (super conductive furnace) or ECF (electric conductive furnace).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides extremely excellent dimensional accuracy by blending a specific propylene polymer resin, optionally with synthetic rubber, and talc and carbon black. , Concerning a resin composition that has heat resistance, mechanical properties, and dramatically improved conductivity.It is known that a conductive resin can be obtained by blending carbon black with a thermoplastic resin.
Regarding polypropylene, conductive resin compositions containing carbon black have been studied and some have been put into practical use.

However, conventional carbon black-containing polypropylene has extremely poor dimensional accuracy and has major drawbacks such as sink marks and warpage.Also, in order to provide a high degree of conductivity, the carbon black compound has a high concentration or specific surface area. However, since it is necessary to make paper containing carbon black, it has disadvantages such as poor mechanical properties and moldability, and the range of applications is extremely limited.

In light of this problem, the inventors of the present invention have conducted extensive studies and found that
By adding a specific propylene polymer, in some cases synthetic rubber, and adding talc of a specific particle size to the round string material, it is possible to make paper with extremely good dimensional accuracy, heat resistance, mechanical properties,
The present invention was completed based on the discovery that a propylene electrolyte composite composition containing nine carbon blacks can be obtained with excellent moldability and dramatically improved conductivity.

That is, the present invention does not contain the following components (a) to (C); Also(
The conductive resin composition contains 2 to 100 parts by weight of component (a) + (b) 10 oil.

('a) 7' propylene polymer resin, optionally extracted, and a composition in which synthetic rubber is blended with (1) 23°C
(2) The propylene content in the extracted soluble matter is 30% by weight or more.
．． Talc (C) carbon black having a diameter of 5 to 20 μm.Thus, the composition of the present invention has excellent dimensional accuracy, high electrical conductivity, and has outstanding heat resistance, hardness, impact resistance, moldability, etc. As a result of its high conductivity, it has excellent electromagnetic wave shielding properties. The composition of the present invention having such characteristics is extremely suitable for the housing field of electronic equipment and wheel equipment that needs to avoid electromagnetic interference, the field of electrostatic protection materials for ICs, etc. The component ra) used in the present invention is a propylene polymer resin polymerized using a Ziegler-Natsuta type catalyst, which is suitable for a wide range of fields such as containers, thin batteries, and surface heating elements. A composition in which a synthetic rubber is blended with this, (t) a soluble content in xylene at 23°C is 10 to 50% by weight, and (2) a propylene content in this extracted soluble content is 30% by weight. 5 or more - Here, as the propylene polymer resin, a propylene homopolymer or a crystalline copolymer resin of propylene and an α-olefin (including ethylene) other than propylene N is suitable. .

Preferably, the a-olefin has 2 to 12 carbon atoms other than propylene.

The majority of the constituent units of the crystalline propylene copolymer resin are propylene, and specifically, for example, crystalline propylene/ethylene block or random copolymer, crystalline propylene/butene block or random copolymer,
6 sheets of crystalline propylene/hexene block or random copolymer, crystalline propylene/heptene block or random copolymer, crystalline propylene/ethylene/butene copolymer, etc., especially those with an ethylene content of 30% by weight or less Crystalline propylene/ethylene block copolymers are preferred.

Such propylene polymer resins can be appropriately selected from commercially available ones.

In addition, as the synthetic rubber used in the present invention, Example t is ethylene-propylene copolymer rubber (EPM, EPDM).
), styrene-butadiene copolymer rubber (SDR, SB
S block copolymer) or its hydrogenated product, imprene rubber, isoprene-imbutylene rubber, etc.

Among these, ethylene/propylene copolymer rubber is preferred.In particular, compositions consisting of crystalline propylene/ethylene block copolymer and ethylene/propylene copolymer rubber are preferred in terms of quality balance. preferable.

In addition, to measure the xylene soluble content at 23°C, put 3 tons of sample into 1000ml of boiling xylene, let it cool to 23°C, and then
This is done by filtering, separating the soluble content, and measuring its weight.

The propylene content in the extracted soluble matter is measured by separating the xylene in the extracted soluble matter and then detecting the precipitate with an infrared spectrophotometer. The talc that can be used in the invention, which is a component (a), has an average particle size of 0.5 to 20 tones.

Preferred talc has an average particle size of 0.5 to 5μ and a top
The particle size distribution of talc, which has a coarse particle content of 10 weight or less and a specific surface area of 15,000 al12 or more, is measured by a light transmission method using a liquid phase sedimentation method. As a measuring device, there is a new CP type manufactured by Takashi Seisakusho.

The average particle size is the particle size at the 50% point on the particle size distribution integral curve. The surface area is measured using a constant pressure ventilation type specific surface area measuring device, such as the powder specific surface area measuring device 5S-1oo manufactured by Takasu Seisakusho, based on the so-called air permeation method, which is a conventional method.

Such talc is made by crushing naturally produced talc (hydrated magnesium silicate) into a fine powder, and the total amount of iron and aluminum as impurities is 0.911r.
The product obtained by finely pulverizing and classifying talc from China, which has a content of 1% or less, is of good quality.

The talc used in the present invention may be used without surface treatment, but it is also possible to use one that has been surface treated with various surface treatment agents. Surface treatment agents include waxes such as low molecular weight polyethylene and low molecular weight polypropylene, saturated higher fatty acids such as stearic acid and palmitic acid,
Anastomotic high RD fatty acid gold such as magnesium stearonate
ill*, unsaturated higher fatty acids such as oleic acid, unsaturated higher fatty acid metal salts such as oleic-magnesium, titanate coupling agents with isopropyl triisostere and tscutitanate, silane coupling agents, polyoxyethylene alkyl ethers Various surfactants such as
As carbon black, which is one component, general carbon black such as furnace black and channel black can be used.In particular, carbon black with a large surface area, S, C,
F.

(5uper Conductive Furnace
), F:, C, F.

(Electric Conductive li'u
rnace) and Ketjenblack (trade name of AKZO) are advantageous in that a high degree of conductivity can be obtained with a small amount of blending. The specific surface area is gsow//f or more, especially 9
Ketjen black of 00-/f or more is particularly preferable in that it can impart a high degree of conductivity with a very small amount of addition.The present invention uses the above-mentioned components (a), (b), and (C). However, their blending ratios are (a) 25-90% by weight based on (a) + (b), (1!) 75-10% by weight based on the same standard, and (C) (→+ (b) 10
A range of 2 to 100 parts by weight is suitable for 0 parts by weight.

If the amount of component (b) talc is less than the above range, there will be no improvement in dimensional accuracy or conductivity, and if it exceeds the above range, mechanical properties may deteriorate.

If the blending amount of component (c) carbon black is less than the above range, the electrical conductivity will be poor, and if it exceeds the above range, 1.
Mechanical properties may deteriorate, which may be undesirable. Carbon black with a large specific surface area provides a high degree of conductivity at a relatively low concentration within the above blending range.

Among these, those with a specific surface area of 5 soj/f or more, especially 90
Ketjen black of oi/f or higher provides a high degree of conductivity in extremely low concentration regions.

Additional components may also be incorporated into the composition of the present invention. Additional components include phenolic, sulfur, and phosphorus antioxidants; higher fatty acid derivatives such as metal salts, amides, and esters; organic or inorganic pigments; ultraviolet absorbers;
Antistatic agent; copper damage inhibitor; neutralizing agent; antifoam agent; flame retardant: thermoplastic resins and fillers other than those used in the present invention. It may also be used in the form of a rubber compound.

Among thermoplastic resins other than those used in the present invention, in particular, when an ethylene polymer having a density of 0.945 t/cd or more and having a unique interaction with the carbon black surface is used, the conductivity of the composition is improved. further improves.

As fillers other than talc, in addition to general-purpose fillers such as calcium carbonate, mica, and glass*#, other conductive fillers such as graphite, carbon fiber, metal fiber, and metal powder can be used.

The composition of the present invention is produced using a conventional mixing machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, or a Brabender plastogram.

The conductive resin composition of the present invention significantly improves the extremely poor dimensional accuracy, which is a major drawback of conventional conductive polypropylene resin compositions, and also has better conductivity than conventional conductive polypropylene resin compositions. This is an epoch-making development that has been dramatically improved.

Particularly preferably, component (a) has (1) an extractable content of 15 to 50% by weight at 23°C x t/h, and (
2) The propylene content in this extracted soluble matter is 35 g#"
Using 50 to 80 wt% of a crystalline copolymer resin of propylene and other α-olefins, or a resin composition in which synthetic rubber is blended with it, as the component (b). , 20 to 50 pieces of talc with an average particle size of 0.5 to 20μ
Weight% and carbon black of component (C) (a)
+ (b) When the composition is composed of 4 to 50 parts by weight per 0 parts by weight, the dimensional accuracy is particularly good, the molding shrinkage rate is 0.6% or less, and the molded product has no sink marks or warpage. It has revolutionary properties as a crystalline propylene polymer-based conductive resin composition.

Example 1 Crystals obtained by copolymerizing propylene and ethylene using a Ziegler-Natsuta catalyst and having an ethylene content of 13% by weight, a melt flow rate of 15 f710 minutes containing 21 weight % of xylene extractables at 23° C. A polypropylene/ethylene block copolymer (2) was obtained. 2 in this (4)
The propylene content in the soluble matter extracted with xylene at 3°C was 50% by weight.

This (4) powder contains 65 parts by weight, the average particle diameter is 2.811. OOO+-j/l
35 parts by weight of fine talc (containing a total of 0.1% by weight of iron and aluminum as impurities) and 8 parts by weight of talc (with a specific surface area of 1. 000 m'/f) and 0.2 parts by weight of 2.6-di-t-goglu-4-methylphenol were mixed uniformly in a super mixer, and then in a twin-screw extrusion machine with a diameter of 30 mm. AN and pellets and 17.

This pellet is made into a screw in-line injection molding machine.
A test piece was molded at 60°C and evaluated.

For comparison, the propylene/ethylene block copolymer ① had a melt flow rate of tst, /l.

Crystalline propylene homopolymer (O, talc/D
Various proportions of Ketjenblack 0 were mixed with 100 parts by weight of these and 8 parts by weight of Ketjenblack 0 were mixed and mixed and injection molded in the same manner as before, and the test pieces were evaluated.

These results are shown in Table 1. As can be seen from the results in this table, the dimensional accuracy of the examples was dramatically superior to that of the comparative examples, and the conductivity was also good.

(Left below) Example 2 Crystalline propylene/ethylene polymer obtained by copolymerizing propylene and ethylene using a Ziegler-Natsuta catalyst
100 parts by weight of Tsuku copolymer and 100 parts by weight of ethylene-propylene copolymer rubber (IP07P) were mixed and kneaded to obtain an ethylene content of 10 parts by weight at 23°C, and a xylene-extractable content of 18 parts by weight.
A propylene/ethylene copolymer composition containing % by weight was obtained.

The propylene content in the xylene-extracted portion of this composition at 23° C. was 45% by weight.

A copolymer composition (total) of jin, an average particle size of 1.3 tones, a coarse particle content of 5 tones or more of 4%, and a specific surface area of 28,000 dl.
lf of fine powder talc manufactured from Chinese talc in various proportions, and further 8 parts by weight of Ketjen black (specific surface area 1.0
OOj/l) were mixed, kneaded, and injection molded into test pieces in the same manner as in Example 1, and the physical properties were measured. Propylene homopolymer ■ and 18 parts by weight of ethylene-propylene copolymer rubber (Mitsubishi Yuka 11EP07P) were mixed and kneaded to give a xylene extract at 23°C (propylene content 28% by weight) of 18% by weight.075% by weight 1 part and 25 parts by weight of the same talc as above, and then o+cn
A mixture of 100 parts by weight of Ketjenblack, which was the same as that used on the type 8 bone part, was mixed and kneaded and then injection molded in the same manner as above, and the test pieces thereof were evaluated.

As can be seen from the results summarized in Table 2, the compositions of the examples had extremely superior dimensional accuracy and conductivity, and had good heat resistance, - resistance, and impact resistance, compared to those of the comparative examples. (Space below) Example 3 60 parts by weight of the crystalline propylene/ethylene block copolymer (A) of Example 1, 40 parts by weight of fine talc, and 15 parts by weight based on 100 parts by weight of the total amount of these. Ketjen black and 0.2 parts by weight of 2.6-di-t-butyl-4-methylphenol were mixed and kneaded to form pellets in the same manner as in Example 1, and the pellets were injection molded to form a computer. The molded housing has good electromagnetic shielding properties, and has excellent cutting and dimensional accuracy.
The moldability, heat resistance, and mechanical properties were also good.

Example 4 When a similar experiment was conducted in Example 3 using 40 parts by weight of Cmbot CX S-99 (Furnace Black trade name manufactured by Cabot) in place of 15 parts of Ketjen Black, electromagnetic shielding properties, A computer housing with extremely excellent dimensional accuracy and heat resistance was obtained.

Patent applicant: Mitsubishi Yuka Co., Ltd. Agent: Patent Attorney Hidetoshi Furukawa

Claims (1)

[Claims] The following components (a) to (C) are blended in Table 9, and the components (a) and (b) are each 25 to 25 on the basis of (a) + (b).
90% by weight and 75 to 10% by weight, and (c) component (a) + (6) 1 o. A conductive resin composition containing 2 to 100 parts by weight of keratin and 1% by weight. (a) 7' Robylene polymer resin, optionally blended with synthetic rubber;
(2) The propylene content in the extracted soluble matter of the kernels is 30% by weight or more; and (b) The average particle size as measured by a light transmission method using a liquid phase sedimentation method is 0.5.
~20μ talc (c) carbon black