JPH01101374A - Electrically conductive powdery molding material - Google Patents

Abstract

PURPOSE:To obtain an electrically conductive powdery molding material having low specific resistance and small variation of specific resistance in a lot and between lots, by mixing a powdery polymer material with electrically conductive powder. CONSTITUTION:The objective electrically conductive powdery molding material is produced by the dry-mixing of (A) a powdery polymer material preferably produced by crushing a thermosetting resin such as phenolic resin or melamine resin to particle size of finer than 200 mesh and (B) conductive powder, e.g. highly conductive powder having a specific resistance of <=10<2>OMEGA.cm (e.g. electrically conductive powder such as carbon black, graphite or ketjenblack, or carbon fiber, etc.) or semiconductive particles having a specific resistance of 10<2>-10<10>OMEGA.cm using Henschel mixer or ball mill, etc. The molding material is composed of the particle 8 of the component A covered with the particles 9 of the component B. A low and uniform specific resistance can be attained in the present material because of good and uniform contact state between the particles 9 of the powdery component B.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a powdered conductive molding material.

[Conventional technology]

Conventional conductive polymer molding materials are produced by roll-kneading polymer materials and conductive powder, forming them into sheets, and then forming them into pellets. It has the disadvantage that there is large variation between lots.

[Problem that the invention seeks to solve]

Therefore, a molded article formed using such a conductive molding material also exhibits the defects of the molding material itself.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a powdery conductive molding material that has a low resistivity and small variations in resistivity within and between lots.

[Means for solving problems]

In order to achieve the above object, the powdery conductive molding material of the present invention has a structure in which a powdery polymeric material and a conductive powder are mixed.

[Effect]

The inventors used conventional roll kneading and sheeting.

When using conductive molding material obtained through pelletization,
In the process of conducting repeated research to determine the cause of the problem of high resistivity and wide variation, it was discovered that the conductive powder was not uniformly dispersed within the pellets. It was also found that this was caused by the conductive powder being unevenly distributed on the outer periphery side of the pellet or unevenly distributed on the center side depending on the kneading method of roll kneading. When pellets with such uneven distribution of conductive powder are used, when molding the pellet, the contact state between the conductive powders will differ depending on the manner of uneven distribution of the conductive powder.
It was found that this caused variations in the resistivity of the conductive layer and increased the resistivity. Furthermore, as a result of repeated research, we found that by making a polymer molding material into a powder form without rolling it, and mixing this powdered polymer material with conductive powder to make the conductive molding material itself into a powder form, The inventors have discovered that all of the above problems can be solved and have arrived at this invention.

The powdered electrically conductive molding material of the present invention is obtained using a powdered polymer material and electrically conductive powder.

The above-mentioned powdered polymer material is preferably one obtained by pulverizing a thermosetting resin such as a phenol resin or a melamine resin using a conventionally known pulverizing method, but in some cases, pulverizing a thermoplastic resin or rubber may also be used. Can be done. The particle size of such a powdered polymeric material is preferably 200 mesh or less.

In addition, examples of conductive powder include carbon black, graphite,
Highly conductive powder such as conductive carbon black such as Ketchen black or carbon fiber with a specific resistance of 10"Ω・CII+ or less, conductive zinc white, conductive tin, etc. 10" to 10
'Ω' cm, T i Oz, Fe, 03 etc.
04 to 106 Ω'cm, and even SnO, Z
Conductive metal oxides or metal oxides having a conductivity of 10 6 to 1 OR Ω·cm such as nO can also be used. If the former is used, a conductive molding material is obtained, and if the latter is used, a semiconductive molding material is obtained. Thus, in the present invention, materials exhibiting semiconductivity are also included in the scope of conductive molding materials. Further, the conductive powder includes not only powder or granular powder, but also fine fiber flakes such as carbon fiber. The powdery conductive molding material of the present invention can be obtained by dry mixing the powdery polymer material and conductive powder using a Henschel mixer, a ball mill, or the like.

The powdered conductive molding material thus obtained is
As shown in the figure, the conductive powder particles 9 are attached to the outer periphery of the particles 8 of the powdered polymer material, and the contact between the conductive powder particles 9 is good and uniform, resulting in a specific resistance. is small, and variations in resistivity within and between lots are reduced. In contrast, conventional roll kneading,
The molding material obtained through sheeting and pelletizing is
As shown in the figure, the conductive powder particles 9 are incorporated into the pellet 10, and the conductive powder particles 9 are not in smooth contact with each other, so the specific resistance increases. ing. Furthermore, the distribution state of the conductive powder particles 9 within the bellet 10 is greatly affected by roll kneading and the like, and therefore tends to be unevenly distributed, causing variations in resistivity.

〔Effect of the invention〕

As described above, the powdered conductive molding material of the present invention does not incorporate conductive powder into the polymeric material.- The polymeric material is powdered, and this and the conductive powder are mixed to form a powder. Because of the shape, the conductive powder particles are distributed around the outer periphery of the particles of the powdered polymer material, and the contact between the conductive powder particles is improved and the specific resistance is reduced. Also,
Since the conductive powder particles are distributed around the outer periphery of the polymeric material particles and are less likely to be unevenly distributed, variations in resistivity within and between lots are reduced. In particular, when trying to obtain semiconductivity by using semiconducting particles of about 10" to IQ + 6 Ω cm as conductive powder, it is difficult to control the ridges to a constant semiconductivity. According to the method of this invention, since the contact state of the conductive powder particles is improved,
Using particles with relatively high resistivity such as tin oxide and zinc oxide,
The semiconductivity can be easily controlled within a set range.

Next, examples will be described together with comparative examples.

〔Example〕

The phenol resin and other components were blended in the following proportions.

[Blending ratio]

Phenol resin 100 parts by weight Curing agent (hexamine) 13 Ca (0 [l)2
2 〃Wallast Night
10 〃Glass fiber 50 〃Asbestos 10 〃Auxiliary agent
2 Next, the above-mentioned mixture was sufficiently roll-kneaded and then formed into a sheet, which was then pulverized using a conventionally known pulverizer to reduce the particle size to 50 μm.
It was set to about.

On the other hand, the following was prepared as a conductive powder.

*Semi-conductive region Next, mix the above-mentioned fine powder assembly of the polymeric material and conductive powder in a ratio that will give a predetermined conductivity value, to obtain the desired powdered conductive molding material. Ta.

Using the conductive molding material thus obtained, a molded sheet with dimensions of 10100 x 100 x 1 was made by compression molding, and its specific resistance was determined and shown in Figures 3 to 5. In this case, we used a conventional product made by using the same conductive powder as the practical product, roll-kneaded it, made it into a sheet, and made it into pellets as it was, and as a control, we showed a sheet-like molded product that was compression-molded in the same way as the practical product. ing. In FIGS. 3 to 5, curve A shows the specific resistance of the implemented product, and curve B shows the specific resistance of the conventional product. As is clear from the comparison between curves A and B, it can be seen that even if conductive powders from the same manufacturer are used, the conductivity of the different products is higher.

In addition, for the separate products using Ketchen Black, 100 x 100 x 1a + m is made by compression molding.
20 Sheets 1- were made, and their specific resistance is shown in FIG. 6 in comparison with that of 20 conventional molded sheets manufactured in the same manner as above. In the figure, the band-like curve A is the actual product, and the band-like curve B is the comparative product. As is clear from the comparison of both curves A and B, it can be seen that the variations in resistivity of the different products are small.

Similarly, C-3nO□, F in the semiconductive region
The specific resistance of a sheet formed from ZnO in the same manner as above was compared with that of a sheet manufactured in the same manner as before using the same amount of conductive powder.
This is shown in Figures 9 to 9. In these figures, curve A
is the actual product, and curve B is the comparative product. As is clear from the comparison between curves A and B, even in the semiconductive region, high conductivity can be achieved with a small amount of the product.

Next, 20 sheet-shaped molded products were made using C-3nO in the same manner as above, and their specific resistance was determined and compared with that of 20 conventional products manufactured in the same manner as above. Shown in the figure. In FIG. 10, the band-like curve A is a different product for actual use, and the band-like curve B is a different product for comparison. curves A and B
As is clear from the comparison, it can be seen that the variations in resistivity of the different products are small.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the distribution state of conductive powder particles of the powdered conductive molding material of the present invention, FIG. 2 is an explanatory diagram of the distribution state of conductive powder particles of a conventional example, and FIGS. Figure, Figure 5,
Figures 6, 7, and 8. FIG. 9 and FIG. 10 are resistivity curve diagrams. 8...Polymer material particles 9...Conductive powder particles Patent applicant Tokai Rubber Industries Co., Ltd. Agent Patent attorney Yukihiko Saikei Figure 1 112 Figure ■7・V"/. 113 Figure IF4 Figure 5 Figure 6 V'''°'° Figure 79 OT Figure 10

Claims (2)

[Claims] (1) Powdered conductive molding material made of a mixture of powdered polymer material and conductive powder. (2) The powdery conductive molding material according to claim 1, wherein the powdery polymer material has a particle size of 200 mesh or less.