JPH01112606A - High toughness conductive resin sheet - Google Patents

Abstract

PURPOSE:To perform contraction, pressing, punching, folding, etc., under cold condition by mixing a certain amount of either carbon black solely or both of the carbon black and graphite with a crystalline thermoplastic resin, performing rolling process at a specific temp., and by giving it a certain specified value of tensile strength, tensile rupture energy per unit area, and volume specific resistance. CONSTITUTION:A crystalline thermoplastic resin is mixed with either carbon black solely or both of the carbon black and graphite in a proportion of 100 parts by weight to 25-240 parts by weight. The temp. of the original web at the time of rolling shall exceed the point 80 deg.C below the melting point of the crystalline thermoplastic resin and be under the point 20 deg.C over this melting point. This mixture substance shall be given a tensile strength of 400kg/cm<2> or more, a tensile rupture energy per unit section area of 500kg-cm/cm<2> or more, and a volume specific resistance of 10<-1>-10<7>OMEGA-cm. The crystalline thermoplastic resin shall consist of polyolefin type resin such as polyethylene or polypropylene, which is difficult to have elastic recovery after rolling.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a high-toughness conductive resin sheet material, which has high toughness and can be subjected to processing such as drawing, pressing, punching, and bending, especially in cold conditions. This invention relates to a conductive resin sheet.

[Conventional technology]

Currently, conductive plastic materials are used for antistatic materials, planar heating elements, electrodes for dust collectors, electrodes for batteries, electromagnetic shielding materials, etc., and will continue to be used in the future. It is thought that it will become more widespread. Methods for obtaining such conductive plastics can be divided into filling plastics with conductive fillers, or synthesizing conductive polymers.Currently, conductive plastics are For example, plastics “V” account for the majority of plastics and are being put into practical use.

1.34, No. 12. The former, as seen on pages 19 to 68. Then, the volume stiffness is 10-
As conductive plastics having a resistance of about 1 to 10 7 Ω-c, m, the best known examples are thermoplastic resins filled with carbon black, carbon fibers, metal flakes, metal fibers, etc.

In particular, with a volume resistivity of about 10-1 to 107 Ω-cm,
Examples of materials with high strength and elastic modulus include nylon, ABS, polycarbonate, polybutylene terephthalate, polyphenylene sulfide,
There are products using polyacetal, but these have low elongation and cannot be used in cold drawing, pressing, punching, etc.
It is impossible to perform processing such as bending. On the other hand, materials with a volume resistivity of about 10-1 to 107 Ω-cm and high elongation include those using polyolefin resin as haath resin, and those using ethylene-vinyl acetate as seen in JP-A-61-7681. There are products using copolymers, but these have low strength and modulus of elasticity and are very soft, so they cannot be drawn or drawn in the cold.
When subjected to processing such as pressing, punching, bending, etc., the shape after processing cannot be maintained.

[Problem that the invention seeks to solve]

As described above, a tough conductive resin sheet that combines strength, elastic modulus, and elongation has not been developed.

In view of this point of view, it is an object of the present invention to provide a highly tough conductive resin sheet that not only has excellent conductivity but also can be processed by cold processing such as curving, pressing, punching, and bending. It's about doing.

[Means for solving problems]

That is, the present invention contains carbon blank alone or both carbon black and graphite in a total of 25 to 240 parts by weight per 100 parts by weight of crystalline thermoplastic resin, and the melting point of the resin is -80'C or higher. Rolled at a temperature of -20°C or lower, has a tensile strength of 400 kg/cm2 or higher, and has a tensile energy of failure per unit cross-sectional area of 500 kg-cm/c.
m2 or more and a volume resistivity of 10-1 to 107Ω-c
This is a highly tough conductive resin sheet material characterized by having a thickness of m.

The present invention will be explained in detail below.

First, high toughness in the present invention means that strength, elastic modulus, and elongation are all high, and in particular, tensile strength is 40
0 kg/cm2 or more and the tensile breaking energy per unit cross-sectional area of the sheet is 500 kg/cm2 or more. Note that the tensile strength at breakage indicates the integral value of tensile strength and elongation. In addition, the tensile strength and tensile breaking energy at this time are JIS K
6301 Danhe mountain shape No. 1 test piece was used, the tensile test speed was 50 mm/min, and the chuck opening was 40 mm.
(Direct) is used when the tensile test is performed.

If the tensile strength is less than 400 kg/cm2 or the tensile breaking energy is less than 500 kg-cm/cm2, cracks may occur when cold rolling, drawing, pressing, punching, bending, etc. , it becomes impossible to maintain the shape after processing.

Furthermore, in the present invention, tetraelectricity means 10-' as mentioned above.
This means that there is a volumetric resistance of ~107 Ω-cm, and this range of resistance values was chosen because anything exceeding 107 Ω-cm is considered to be antistatic, which is the object of the present invention. It is difficult to use it for applications such as materials, sheet heating elements, dust collector surface electrodes, battery electrodes, electromagnetic shielding materials, etc., and those that have not yet reached io'''Ω-cm are within the composition range of the present invention. That's because you can't get it.

Next, crystalline thermoplastic resins used in the present invention include polyethylene, polypropylene, nylon-6, nylon-66, polyethylene terephthalate, polybutylene terephthalate, polyacetal, ethylene-vinyl alcohol copolymer, and the like. Preferably, polyolefin resins such as polyethylene and polypropylene are used, which are unlikely to undergo elastic recovery after rolling.

In addition, in the present invention, 2. Only carbon black or both carbon black and graphite are used as the husbandry material. Examples of carbon black include conventionally known Ketschen black, acetylene blank, furnace blank, lamp black, thermal black, channel black, roll black, disk black, and the like. The graphite may be natural graphite or artificial graphite. This graphite itself has higher conductivity than carbon black, and has a particle size of 1 to 600 μm.
In terms of moldability, the particles preferably have an average particle diameter of 2 to 100 μm, more preferably 4 to 80 μm. Furthermore, the above-mentioned carbon black or graphite can be blended into a crystalline thermoplastic resin and kneaded without any treatment on its solid surface, or it can be kneaded by adding an appropriate dispersion aid. It is also possible to coat the surface with a suitable resin and mix it into a crystalline thermoplastic resin as a solid-resin composite powder and knead it.

Methods for coating this solid surface with resin include the commonly known interfacial polymerization method, in 5 in situ polymerization method, in-liquid curing coating method, phase separation method from an aqueous solution, phase separation method from an organic solution, and in-liquid polymerization method. There are drying methods, melt dispersion cooling methods, inclusion exchange methods, powder bed methods, suspension coating methods in liquid, spray drying methods, vacuum deposition methods, electrostatic coalescence methods, etc. A more preferable method is to apply vinyl to the solid surface. A resin solution or A method of contacting with a dispersion liquid can be mentioned.

Next, in the present invention, the blending ratio of the crystalline thermoplastic resin and carbon blank alone or both carbon blank and graphite is 25 to 240 parts by weight per 100 parts by weight of the crystalline thermoplastic resin, preferably L<4;! The amount is 40 to 150 parts by weight. What if the total blending ratio of carbon black alone or both carbon black and graphite exceeds 240 parts by weight? If R kneading is not possible, or if the original fabric can be manufactured by extrusion molding or press molding, cracks may occur in the sheet after rolling, or even if a rolled sheet without cracks can be formed, it will still not work as defined by the present invention. High toughness cannot be obtained.

If the amount is less than 25 parts by weight, high toughness as defined by the present invention can be obtained, but it is not possible to obtain satisfactory physical properties in terms of electrical conductivity.

The high-toughness conductive resin sheet of the present invention can be produced by using an appropriate blender such as a co-kneader, a Banbury mixer, a mixing roll, a pressure kneader, a twin-screw extruder, or a single-screw extruder in a conventional manner. Thermoplastic resin and carbon black alone or both carbon blank and graphite are uniformly mixed and kneaded within the above-mentioned mixing ratio range, preferably formed into pellets, and then formed by extrusion molding, press molding, etc. The raw fabric obtained is rolled by at least one pair of rolls or a press. In roll rolling, uniaxial rolling or biaxial rolling in longitudinal and transverse directions can be performed. In particular, when performing cold processing such as drawing, pressing, punching, etc., it is preferable to perform biaxial rolling because a sheet without anisotropy has better workability. Moreover, the rolling can be carried out in several steps, and even a molded product that has been rolled by -degrees may be rolled again after heating. In this case, the rolling ratio, which indicates the thickness of the original fabric relative to the thickness of the rolled product, is desirably 2 times or more, especially 2 times to 20 times. If the strength exceeds 20 times, a sheet with very high strength can be obtained, but the elongation is low, making processing such as cold drawing, pressing, punching, etc. difficult. Furthermore, the temperature of the original fabric during rolling is an important control item in obtaining the resin sheet of the present invention, and the temperature range is -80°C or higher, the melting point of the crystalline thermoplastic resin used as a matrix, The melting point must be 120°C or less. If rolling is not carried out within this temperature range, it is not possible to orient the crystalline thermoplastic resin, improve the brittleness of the product sheet, and form a tough conductive resin sheet. That is, when rolling is carried out at a temperature lower than the melting point of the crystalline thermoplastic resin -80°C,
Insufficient softening of the resin makes rolling forming difficult, and rolling at temperatures higher than the melting point +20°C results in insufficient orientation of the crystalline thermoplastic resin, improving the brittleness of the resulting component sheet. Not done.

In addition to the above-mentioned resin, carbon black, and graphite, the composition constituting the sheet-like product of the present invention includes mica, glass flakes, talc, calcium carbonate, and various stabilizers for the purpose of modifying molded products. One or more types of antioxidants, inorganic powders such as metal powders, and fibrous materials such as carbon fibers, glass fibers, or metal fibers,
It can be contained as appropriate. In addition, even if it is other than the above-mentioned inorganic powder or fibrous material, it can be appropriately contained as long as it does not impair the properties after rolling.

〔Example〕

Hereinafter, the effects of the present invention will be illustrated in more detail with reference to Examples.

Examples 1 to 3 and Comparative Examples 1 to 2 Furnace plaque was used as a carbon blank with a melting point of 13
It was mixed with 100 parts by weight of high-density polyethylene at 0°C in the proportions shown in Table 1, and mixed with 15 parts by weight using a Banbury mixer.
Mix at 0 to 180°C for 5 minutes, knead again at 140 to 170°C using two rolls, make pellets using a sheet cutter, and use a 40mm extruder to knead the pellets at cylinder temperature. A raw sheet with a width of 100 mm and a thickness of 5 mm was molded under conditions of 160 to 240°C and a die temperature of 200 to 240°C.

These obtained raw sheets were rolled by feeding them between a pair of rolling rolls with a diameter of 170 mm, a rolling blade of 2 Qton, and a temperature of 100° C. to obtain rolled sheets with a thickness of 1 mm in Examples 1 to 3 and Comparative Examples 1 to 2. I got it.

Along the rolling direction from these rolled sheets, JIS
A dumbbell-shaped No. 1 test piece of K 6301 was prepared, and using this test piece, a tensile test was conducted at a tensile test speed of 50 mm/win and a distance between chucks of 40 mm, and the tensile strength, tensile modulus, and elongation rate were determined. , tensile breaking energy and volumetric resistance were measured, and the results are also shown in Table 1.

In addition, regarding the sheet of Comparative Example 2, many cracks were generated in the sheet after rolling, and the physical properties could not be measured.

Further, in order to confirm shape retention, the following test was conducted. That is, using a unidirectional drawing tester whose front and side views are shown in FIGS. 1(a) and 1(b), a short piece of 100 mm in length and IQ mm in width was A planar specimen 3 was held between specimen holders 2 with an interval t = 12 mm and a lower corner radius of curvature r 2 = 2 mm, and kept at room temperature (23°C).
Thickness L+=10mm, tip curvature radius r+=5
A molded product 4 having a molded product depth h as shown in a perspective view in FIG. 2 was prepared by lowering the pressure draft 1 by 15 mm, and the recovery rate at that time was measured. The recovery rate was determined by the following formula.

(15 mm) The molded product depth h at this time is a value measured 24 hours after molding into the shape 4 in FIG. 2, and is 0≦ε<0.
2 is represented by ◯, 0.2≦ε≦1 is represented by △, and those in which cracks occur during molding are represented by ×.

The results are also shown in Table 1.

Examples 4 to 7 and Comparative Examples 3 to 5 Two types of carbonaceous materials, Ketschen black as carbon black and natural graphite with an average particle size of 6 μm as graphite, were added to a loomi part of high-density polyethylene with a melting point of 130°C as shown in Table 1. Mixed in the proportions shown in and under the same conditions as Examples 1 to 3, the width was 1'00 mm, the thickness was 1.5 mm, 2.5 mm, and 5 m.
Three types of raw fabric sorted m were molded and rolled by the same means as in Examples 1 to 3 to obtain rolled sheets with a thickness of 1 mm.

The rolling conditions are as shown in Table 1.

In addition, in the same manner as described above, the material was kneaded into pellets using a Banbury mixer, and an extruded sheet with a width of 100 mrn and a thickness of 1 mm was made using a 40 mm extruder under the conditions of a cylinder temperature of 160 to 240 °C and a goo temperature of 200 to 240 °C. Molded.

The physical properties of these rolled and extruded sheets were measured in the same manner as described above, and the results are also shown in Table 1.

Examples 8 to 9 and Comparative Example 6 As carbon fiber, furnace black was blended with polypropylene 10 (Nffifi part) having a melting point of 170°C in the ratio shown in Table 1, and heated at 180 to 210°C using a Banbury mixer. Mix for 5 minutes, knead again using two rolls at 170-200°C, make pellets using a sheet cutter, and use a 4Qmm extruder to knead the pellets at a cylinder temperature of 180-240°C.
, width 100 under the condition of Gui temperature 200-240℃
mm.

A raw sheet with a thickness of 5 mm was molded.

These obtained raw sheets were fed between a pair of rolling rolls with a diameter of 170 mm, a rolling blade of 2 Qton, and a temperature of 100° C., and rolled to obtain rolled sheets with a thickness of 1 mm shown in Examples 8 and 9.

In addition, in the same way as above, the pellets were kneaded with a Banbury mixer and made into pellets using a 49 mm extruder, and the cylinder temperature was 180 to 240 °C and the goo temperature was 200 to 240 °C. The extruded sheet shown in Example 6 was molded.

The physical properties of these rolled and extruded sheets were measured in the same manner as described above, and the results are also shown in Table 1.

Example 10 and Comparative Example 7 The raw sheets used in Example 5 and Comparative Example 4 were used in Examples 1 to 3.
Using the same rolling rolls as above, rolling was first performed in one direction, and then in a direction perpendicular to that direction. Physical properties similar to those described above were measured for these rolled sheets along the second rolling direction, and the results are also shown in Table 1.

In addition, the following tests were conducted to confirm drawing workability. That is, using a drawing tester as shown in FIG.
Clamp the specimen with a specimen holder 2 with a lower corner radius of curvature r4 = 3 mm,
Diameter d+ = 50mm, tip corner curvature radius r3 = 7mm
The punch 5 is lowered by 50 mm to produce a molded product 4 as shown in Fig. 4, and those with no cracks are marked as ○,
Those in which cracks occur are indicated as ×. The results are also shown in Table 1.

〔Effect of the invention〕

As is clear from the above examples, the present invention provides a resin sheet that not only has excellent conductivity but also exhibits excellent workability in cold drawing, pressing, punching, bending, etc. There are some extremely notable contributions to the development of industry.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are (a) a front view, (b) a side view, and Figure 2 is a unidirectional drawing tester used in the examples.
A perspective view showing a molded product obtained using the testing machine shown in Figure 3.
The figure is a front view showing another drawing tester used in the examples, and FIG. 4 is a front view showing a molded product obtained using the tester shown in FIG. 3. 1-pressure cutting, 2-sample holding, 3-sample, 4-molded product, 5
-Ponchi. Patent applicant Nippon Steel Chemical Co., Ltd. Nippon Steel Corporation

Claims (4)

[Claims] (1) A total of 25 to 240 parts by weight of carbon black or both carbon black and graphite is contained in 100 parts by weight of the crystalline thermoplastic resin, and the melting point of the resin is -8
Rolled at a temperature of 0°C or higher and melting point +20°C or lower, has a tensile strength of 400kg/cm^2 or higher, a tensile breaking energy per unit cross-sectional area of 500kg-cm/cm^2 or higher, and a volume resistivity of 10^- A highly tough conductive resin sheet material having a resistance of ^1 to 10^7 Ω-cm. (2) The highly tough conductive resin sheet according to claim 1, wherein the crystalline thermoplastic resin is a polyolefin resin. (3) The highly tough conductive resin sheet according to claim 1 or 2, wherein the rolling ratio is 2 times or more. (4) The highly tough conductive resin sheet according to any one of claims 1 to 3, wherein the rolling direction is biaxial.