JPS60133604A - Moldable conductive material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Uses and purposes of inventions] The present invention relates to a novel moldable conductive material.

Conventional conductive +, l )'3+ is made of metals such as copper, aluminum, silver, nickel, etc. Although metal materials have excellent rolling workability and wire drawability, their processing power is extremely high (human beings).Furthermore, as the size of metal materials increases, their bending properties rapidly deteriorate. It has a nature.

Another disadvantage of metal materials is that they have a high density and are inferior in light weight.

The present invention has been made based on this point, and its purpose is to provide a conductive material that has excellent moldability, bending properties, and light weight.

[Summary of the Invention] The gist of the present invention is to form a rubber mixture in a predetermined shape with volume expansion, which is made by blending at least 15 parts by weight of expandable graphite with 100 parts by weight of natural rubber or synthetic rubber. A moldable conductive material characterized by being heat-treated at a temperature of 180° C. or higher after being placed in a restraining container.

In the present invention, expandable graphite refers to a graphite intercalation compound. In other words, graphite is a hexagonal crystal of carbon made up of layers of six-membered ring polymers, but the bonding force between each layer is very weak, and there are various chemical substances between the layers. can be combined.

For example, by reacting sulfuric acid, an alkali metal, a halogen compound, etc., a graphite intercalation compound in which a sulfate radical, an alkali metal, a halogen, etc. are bonded between layers can be obtained.

In many of these graphite intercalation compounds, when heated to a temperature of 180'C or higher, the space between the layers on the six-membered ring polymerization surface expands, and the volume expands tens to hundreds of times. It has the property of The most widely used expandable graphite is
It is acid-treated graphite with sulfate groups bonded to it. Acid-treated graphite is obtained by wet-oxidizing graphite in a solution consisting of a mixed acid and an oxidizing agent. As a mixed acid, C is a mixed acid of concentrated sulfuric acid and concentrated nitric acid, and as an oxidizing agent, C is potassium chlorate, potassium dichromate,
Preferably, potassium permancate or the like is used.

In the present invention, the amount of expandable graphite is reduced to 15 parts by weight or more per 100 parts by weight of natural rubber or synthetic rubber, because rubber compositions containing 15 parts by weight or less of expandable graphite are heat-treated. This is because it does not exhibit b conductivity.

The volumetric expansion suppressing container used in the present invention is one that can contain a rubber mixture and undergo -C heat treatment. Appropriate materials for the volumetric expansion suppression container include ceramics and heat-resistant metals. In addition, the internal volume of the volumetric expansion suppression container is 1 of the volume of the rubber mixture enclosed.
~8 times is appropriate.

That is, if the internal volume of the volumetric expansion suppressing container is less than 1 times the volume of the rubber mixture, it is difficult to enclose it, and if it is more than 8 times the volume, the expansion becomes large and no conductivity is exhibited.

The heat treatment temperature of the rubber mixture was increased to 180'C or higher.
This is because the expanding action of expandable graphite does not occur below 180°C. Also, Prelude 1! I! II; Since thermal decomposition gas is generated more easily than the rubber mixture, it is appropriate to provide an appropriate amount of decomposition gas in the volumetric expansion suppression container.

The effects of the present invention are such that a rubber mixture containing at least 15 parts by weight of expandable graphite per 100 parts by weight of natural rubber or synthetic rubber is heated to 180°C after being placed in a volumetric expansion suppression container of a predetermined shape. Heat treatment at the above temperature brings out the expansion power of the expandable graphite, which causes the hexagonal crystals of graphite to intertwine with each other, thereby exhibiting flexibility and conductivity. Furthermore, the rubber component of natural rubber or synthetic rubber is stable up to 180°C;
At temperatures above 0° C., thermal decomposition and carbonization occur, and the carbides produced come into contact with hexagonal graphite crystals and synergistically improve C conductivity.

J3. In the present invention, the rubber mixture may contain, in addition to expandable graphite, a vulcanizing agent, a vulcanization accelerator, a filler, a lubricant, etc.

Example L" Next, examples of the moldable conductive material of the present invention will be described together with comparative examples.

As a comparative example, a rubber composition containing 100 parts by weight of trill rubber, 12 parts by weight of expandable graphite, 15 parts by weight of dioctyl phthalate, 5 parts by weight of zinc white, 2 parts by weight of stearin R, and 0.8 parts by weight of sulfur was prepared with a diameter of 10 mmψ, After extruding to a length of 100 cm, it was vulcanized at 160°C for 10 minutes. The obtained vulcanized rubber has an inner diameter of 1
The molded product was placed in a 2 mm ψ, 105 cm long ceramic tube with 3 mm ψ exhaust ports at both ends (fixed with a plastic ceramic lid, and then heat-treated in an electric furnace at 800°C for 1 hour to form a molded product. I got it.

Comparative Example 2 21 - 100 parts by weight of Lil rubber, 30 parts by weight of expandable graphite,
A rubber composition containing 15 parts by weight of dioctyl phthalate, 5 parts by weight of zinc white, 2 parts by weight of stearic acid, and 0.8 parts by weight of sulfur was extruded to a diameter of 10 mmψ and a length of 100 cm, and then vulcanized at 160°C for 10 minutes. did. The obtained vulcanized rubber was placed in a ceramic tube with an inner diameter of 12 #ψ and a length of 105 cm.
Both ends of the product were fixed with ceramic lids equipped with exhaust ports of 3 mm ψ, and in this state heat treatment was performed in an electric furnace at 160° C. for 1 hour to obtain a molded product.

Example 1 ゛21~100 parts by weight of Lil rubber, 30 parts by weight of expandable graphite,
A rubber composition containing 15 parts by weight of dioctyl phthalate, 5 parts by weight of zinc white, 2 parts by weight of Stearin R, and 0.8 parts by weight of sulfur was extruded to a diameter of 10 mmψ and a length of 100 cm, and then vulcanized at 160°C for 10 minutes. . The obtained vulcanized rubber was placed in a ceramic tube with an inner diameter of 12 s + + ψ and a length of 105 cm, and both ends of the tube were fixed with ceramic lids with 3 mm ψ exhaust ports. A molded product was obtained by heat treatment for a period of time.

Example 2 100 parts by weight of 21-ryl rubber, 30 parts by weight of expandable graphite,
A rubber composition consisting of -C containing 15 parts by weight of dioctyl phthalate, 5 parts by weight of zinc white, 12 parts by weight of stearin, and 0.8 parts by weight of sulfur was extruded to a diameter of 10 mmψ and a length of 100 cm, and then heated at 160°C for 10 minutes. Vulcanized. The obtained vulcanized rubber was placed in a ceramic tube with an inner diameter of 12 mmφ and a length of 105 cm, and both ends of the tube were fixed with ceramic lids with 111 holes of 3 mmφ in diameter. A molded article was obtained by heat treatment for a period of time.

Example 3 21 - A rubber composition comprising 100 parts by weight of Lil rubber, 30 parts by weight of expandable graphite, 15 parts by weight of dioctyl phthalate, 5 parts by weight of zinc white, 2 parts by weight of stetunophosphoric acid, and 0.8 parts by weight of sulfur. It was extruded to a diameter of 10 cm and a length of 100 cm, and then vulcanized at 160°C for 10 minutes. The obtained vulcanized rubber was placed in a ceramic tube with an inner diameter of 12 mmφ and a length of 105 cm, and both ends of the tube were fixed with pyramid lids equipped with 3 mmφ exhaust ports.
A molded product was obtained by heat treatment for 0 hours.

Example 4 A rubber composition containing 100 parts by weight of nitrile rubber, 60 parts by weight of expandable graphite, 15 parts by weight of di-A-cutyl phthalate, 5 parts by weight of di-lead chlorine, 12 ΦM parts of thearine, and 183 parts by weight of sulfur. After extruding the product to a diameter of 10 mmψ and a length of 100 cm, it was vulcanized at 160° C. for 10 minutes. The obtained vulcanized rubber was placed in a ceramic tube with an inner diameter of 12 mmφ and a length of 105 cm, both ends of which were fixed with ceramic lids equipped with exhaust ports of 3 mmφ. A molded product was obtained by heat treatment for 1 hour.

Example 5 100 parts by weight of nitrile rubber, 120 parts by weight of fat-swellable graphite,
A rubber composition prepared by blending dioctyl phthalate-h 1 b 111 (5 parts by weight of zinc white, 2 parts by weight of stearic acid, and 0.8 parts by weight of sulfur) was prepared into a rubber composition having a diameter of 10 mm and a length of 100 cm.
After extrusion, it was vulcanized at 160°C for 10 minutes. The obtained vulcanized rubber was placed in a ceramic tube with an inner diameter of 12 mmψ and a length of 105 cm, and both ends of
1. With ceramic lid. ! A molded product was obtained by heat-treating the molded product in an electric furnace at 800° C. for 1 hour.

The volume resistivity d3 and bending properties of the molded products obtained in the comparative examples and examples thus obtained were measured.

The following table shows the test results. The volume resistivity was tested in accordance with the Japan Rubber Association standard-23o1 "Volume resistivity test method for conductive rubber and plastics". Furthermore, the bending properties were evaluated by fixing one end of the obtained molded product and applying a load of 10 q to the other end (J), and evaluating the molded product as good if it bends and poor if it does not bend.

As is clear from the test results, although Comparative Example 1 has good bending properties, it has no electrical conductivity, and Comparative Example 2 also has electrical conductivity, which is inferior to the other ten bending properties. On the other hand, in the embodiment of the present invention, 1! □7 Formable conductive month is conductive, but bending 'r:j f'l or JQ is good.

[Effect of the invention" The moldability conductivity of the present invention is based on the rubber mixture.

Light i(+, Q
Good conductivity and inexpensive conductivity + AN'l
There are many things that can be done that are of no practical use.

Claims (1)

[Claims] It is made by blending at least 15 parts by weight of expandable graphite with 100 parts by weight of natural rubber or synthetic rubber. A moldable conductive material characterized by placing a rubber mixture in a volumetric expansion inhibiting container of predetermined dimensions, and then heat-treating the volumetric expansion inhibiting container containing the rubber mixture at a temperature of at least 180°C. material.