JPS6248741A - Electrically-conductive rubber composition of light color - Google Patents

Abstract

PURPOSE:An electrically-conductive rubber composition of light color causing a little drop in electrical conductivity in preservation and in use such as washing, etc., having no occurrence of rust, capable of producing all colors, obtained by blending rubber with a dihydric alcohol. CONSTITUTION:100pts.wt. natural rubber or any of various kinds of synthetic rubber is blended with 5-40pts.wt. dihydric alcohol having 50-6,000 average molecular weight, such as methylene glycol, ethylene glycol, diethylene glycol, polyethylene glycol or its mixture to give the aimed electrically-conductive rubber composition.

Description

DETAILED DESCRIPTION OF THE INVENTION C. Industrial Application Field The present invention relates to a brightly colored rubber composition in which a chemical is added to rubber to impart conductivity.

[Prior Art] Rubber is generally an electrical insulator, which causes dust to adhere to it due to static electricity, fires caused by sparks when charged static electricity discharges, and computer malfunction accidents. Since there are various problems such as the occurrence of electrical conductivity, attempts have been made to impart conductivity to rubber. In addition, it has developed into new fields by adding functions by adding conductivity while taking advantage of rubber's elasticity, strength, and other various properties.

Conventionally, carbon black has been the most common composition for imparting electrical conductivity to rubber, but it is black in color and cannot provide a bright color. Other than carbon black, those using metal oxides and their chlorides (JP-A-Sho Go-832H)
Although a bright color can be obtained, there is a problem because when chloride comes out on the rubber surface, it rusts metals such as iron.

[Problems to be Solved by the Invention] As mentioned above, conventionally, when trying to impart conductivity to rubber, there is a problem of rust in light colors other than black.

I had no choice but to use black carbon black. The present invention solves these problems, has high fashionability without reducing conductivity, does not rust, has little decrease in conductivity during storage, washing, etc., and is black in color. It is an object of the present invention to provide a light-colored conductive rubber composition that can produce all other colors. This light colored conductive rubber composition is also useful in anti-static work shoes.

[Means for Solving the Problems] The present invention is characterized by the addition of 5 to 40 parts by weight of dihydric alcohol to 100 parts by weight of rubber. It is characterized by: Here, as the rubber, natural rubber and various synthetic rubbers can be used.

Examples of dihydric alcohols include methylene glycol, ethylene glycol, diethylene glycol, and polyethylene glycol (e.g., average molecular weight of 400, 1000.40
00.8000. 10,000 or 20,000 polyethylene glycol) or a mixture thereof. The dihydric alcohol is added to the rubber by a conventional method such as using an A-R machine.

[Example] Hereinafter, the present invention will be explained in detail using examples.

Acrylic Nitrile Butadiene La Verne Co., Ltd., Ni-Ball 1042 (trademark)) (hereinafter N
The following describes a product in which diethylene glycol and polyethylene glycol 4000 (average molecular weight 4000) (manufactured by Lion Corporation) are added to BR (referred to as BR). Table 1 is a table showing the blending ratios of Comparative Example A and Examples 1 to 3.

Mix the compounded chemicals shown in Table 1 using a roll machine,
After aging for 24 hours, the sheet is made into a sheet with a thickness of about 21111 mm again using a roll machine, and press-vulcanized at 150 degrees Celsius for 20 minutes. The bottom two rows of Table 1 show the results of measuring the volume resistivity and surface resistance of samples 24 hours or more after vulcanization. The measuring device was 887AB manufactured by John Kruk, and the voltage generators 2853 and 2861 manufactured by Yokogawa Electric were used, and the measurement was performed at a voltage of 500 V and humidity of 50%.

The samples of Examples 1, 2, and 3 were immersed in running water at room temperature for 22 hours, dried at 50 degrees C for 30 minutes, cooled for 2 hours in a desiccator at room temperature and 50% humidity, and measured for volume resistivity and surface resistance. was measured and repeated five times to perform a running water test.
The results are shown in Figures 1 and 2.

The test results show that the conductivity under normal conditions of the diethylene glycol-added product is better than that of the polyethylene glycol-added product, but there is a tendency for the conductivity to decrease as the immersion time in running water increases. This is thought to be the result of diethylene glycol being dissolved by water and flowing out. On the other hand, polyethylene glycol has worse conductivity than diethylene glycol under normal conditions, but there is almost no decrease in conductivity even when driftwood is left for a long time. For these reasons, by using diethylene glycol and polyethylene glycol in combination to provide a molecular weight distribution, it is possible to improve the rate of decrease under normal conditions and due to water.

It should be noted that if the dihydric alcohol is less than 5 parts by weight per 100 parts by weight of rubber, it will have almost no effect, and if it is more than 50 parts by weight, it will float on the surface and the properties as a rubber will greatly deteriorate, which is not preferable. 5 to 40 parts by weight are suitable.

Table 2 shows another example (Example 4) according to the present invention and the composition according to JP-A-80-63236 mentioned above (Comparative Example B).
).

The sample of Example 4 was made as follows. Using a 6-inch roll, close the roll at a temperature of 50 to 60 degrees C and apply N
After stranding only BR for 5 minutes, set the roll interval to 3 times, wrap NBR, and mix one-half of the total amount of silica, zinc white, dioctyl phthalate, polyethylene glycol, and Glauber's salt. . Next, diethylene glycol water, which has been pre-mixed with diethylene glycol and water, is mixed with the remaining half of the silica and poured onto the roll. When about half of this has been kneaded, tetramethylthiuram monosulfide and Add dibenzothiazole,
Also, all other chemicals are mixed in and removed from the roll, the roll is closed again, and the roll is passed through three times.The roll interval is set to 5 layers, and the cut is cut out.This is aged for 24 hours, and then the roll machine is used again. A sheet approximately 2mm thick, 150
Press vulcanization was carried out at a temperature of 20° C. for 20 minutes, and the volume resistivity and surface resistance of the second sample were measured after 24 hours or more had elapsed after vulcanization. The result is second
As shown in the bottom two lines of the table.

Next, after immersing the sample in running water at room temperature for 22 hours,
The sample was dried at 0 degrees Celsius for 30 minutes, cooled for 2 hours in a desiccator at room temperature and 50% humidity, and the volume resistivity was measured, which was repeated 5 times to conduct a running water test.

The results are shown in Figure 3.

In addition, the sample was dried for 22 hours in a gear oven at 50 degrees Celsius, cooled for 1 hour in a desiccator at room temperature and 50% humidity, and the volume resistivity was measured, which was repeated 5 times to conduct a drying test. . The results are shown in Figure 4.

Furthermore, an iron plate was plastered and the surface was polished, and as a new surface, a sample was placed on the plate, one weight was placed on it, and the plate was left at room temperature to perform a rust generation test.

Table 3 shows the area ratio of generated rust.

From the above results, Example 4 according to the present invention is equivalent to Comparative Example B with no significant difference in volume resistivity in running water test and dry test, but the rust occurrence situation was I find that an example is better. Although Comparative Example B has a formulation that causes less conductivity deterioration during storage and use such as washing, it can be seen that the composition according to the present invention is even better.

The composition according to the present invention can produce all kinds of colors as a rubber without reducing conductivity if a pigment is mixed in the composition, improves fashionability, and meets JIST-8103 (static electricity). The product was able to fully satisfy the standards for antistatic work shoes.

[Effects of the Invention] Since the present invention is configured as described above, the light-colored conductive rubber composition according to the present invention has conductivity, and this conductivity is maintained during storage and during use such as washing. It has the effect that it has little deterioration, does not cause rust, can produce not only black but also all other colors, and can produce highly fashionable products. Therefore, the light-colored conductive rubber composition according to the present invention is used for various purposes, but is particularly useful for manufacturing work shoes for preventing static electricity.

[Brief explanation of the drawing]

Figures 1 and 2 show the running water test results of Example 1.2.3, Figure 83 shows the running water test results of Example 4 and Comparative Example B, and Figure 4 shows the running water test results of Example 4 and Comparative Example. It is a figure showing the drying test result of B. Agent Patent Attorney Elementary School 1) Chi Zetsu 1 Figure 2 Figure 2 Jou g 1 2J 45th No. 3
Figure 4

Claims (2)

[Claims] (1) Add 5 to 40 parts of dihydric alcohol to 100 parts by weight of rubber.
1. A light-colored conductive rubber composition, characterized in that the composition is made by adding parts by weight. (2) The light-colored conductive rubber composition according to claim 1, wherein the dihydric alcohol is a dihydric alcohol having an average molecular weight of 50 to 6,000.