JPH1041683A - Pressure-molded conductive body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure-molded conductive body which is high in electrical conductivity and electromagnetic shielding properties, by a method wherein conductive powder is filled into a small cylindrical film material and extruded from the film material at pressure-molding to form a network structure composed of a large number of conductive powder aggregates. SOLUTION: Conductive powder 4 is attached to, filled into, or mixed with the inner and the outer wall of small cylindrical base materials 1 to 3 through the intermediary of binder, whereby the conductive powder 4 is filled into the small cylindrical base materials 1 to 3. When the small cylinder base materials 1 to 3 filled with conductive powder are pressed, conductive powder is extruded from both the edges of the cylindrical film 1 or from both the ends and cuts of the curled film 2 and the spiral film 3 to turn into powder aggregates. At this point, conductive powder attached to the inner and the outer wall of the small cylinders 1 to 3 or conductive powder sandwiched in between the small cylinders 1 to 3 is brought into contact with the conductive powder aggregates to form a network structure composed of reticulate conductive powder aggregates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a property as an electromagnetic wave shielding member and can be used for various building materials (for example, walls,
The present invention relates to a pressure-formed body having conductivity that can be applied to plate materials such as floors and ceilings.

[0002]

2. Description of the Related Art Shielding electromagnetic waves that cause interference from the source to the outside to prevent reception interference due to reflected waves of radio waves from high-rise buildings (hereinafter simply including radio wave absorption, Various inventions have been made to achieve electromagnetic wave shielding. For example,
A conductive paint obtained by adding a conductive powder such as carbon, ferrite, and metal powder to the paint is disclosed in JP-A-63-301270.
Cement, mortar, concrete, and the like, to which conductive powder is added to form a conductive cement, a conductive mortar, a conductive concrete, and the like are described in JP-A-4-352395 and the like. Various electromagnetic wave shielding members were made. In addition to these, an electromagnetic wave shield panel obtained by laminating a ferrite layer such as a ferrite-based molded article is disclosed in
No. 73678. Furthermore, Japanese Patent Application No. 3-1
No. 74742 discloses a building material board formed by adding a conductive powder to a waste magnetic tape and a binder.

[0003]

In the above-mentioned molded article to which conductive powder is added using a binder such as cement as described above, since the conductive powder is simply scattered in the matrix, the conductivity and the electromagnetic wave shielding are reduced. A sufficient effect on the properties was not obtained, and a conductive fiber or a conductive wire net was used in combination with the conductive powder. Further, when the amount of the conductive powder added is increased in order to improve the electromagnetic wave shielding property, problems such as a decrease in the strength of the member itself arise. In addition, when a conductive layer (magnetic layer) such as a ferrite-based molded body is laminated and used,
The production was laborious and not economical.

[0004] As a result, a film-shaped substrate of an appropriate size is used, formed into a small cylinder, and once filled with a conductive powder, the conductive powder is removed from the substrate during pressure molding. When extruded to form a large number of conductive powder masses in a pressed body, they form a network structure in the binder.
The present inventors have found that a pressure-molded body having higher conductivity and electromagnetic wave shielding properties can be obtained as compared with molded bodies simply scattered, and have completed the present invention.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a high strength of shielding electromagnetic waves by using a low-cost member and a disposal member, a conductive powder and a binder, and is applicable to a building material board. It is an object of the present invention to provide a simple method for obtaining a certain pressure-formed body.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a press-formed body containing a conductive powder, a small cylindrical base material, and a binder for binding the conductive powder and the small-cylindrical base material. A conductive powder mass formed by being extruded from a small cylindrical substrate, or a mixture mass of a conductive powder and a binder alone,
Or by being scattered in contact with each other, and / or by contacting the conductive powder mass or the mixture mass with the conductive powder attached to the surface of the small cylindrical substrate,
This is achieved by a press-formed body having a conductive network structure formed by chaining in a network and having a volume resistivity of 10 ² Ω · cm or less.

[0007] The present invention has been made in order to solve the above-mentioned problems.
A cylindrical, curled, spiral or other film-shaped member is used as a main substrate (hereinafter, collectively referred to as a small cylindrical substrate in the present specification). First, the small cylindrical substrate and a binder are sufficiently kneaded. (1-10 minutes, preferably 3-5 minutes), then add conductive powder and knead them again. At this time, the binder adhering to the surface of the small cylindrical substrate and the conductive powder adhere to each other, and excess conductive powder enters the small cylindrical substrate. Then, at the time of pressure molding, the small cylindrical base material is once crushed (or broken) by the press pressure, and the conductive powder that has entered the small cylindrical base material is extruded to the outside,
The conductive powder that becomes the conductive powder mass and / or adheres to the small cylindrical substrate surface forms a conductive network structure in the binder. Further, by controlling the pressing pressure, it is possible to increase or decrease the conductivity of the molded body, control the mechanical strength (strength control as required), and control the void ratio.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a pressure-formed body having conductivity according to an embodiment of the present invention will be described.

According to the present invention, there is provided a press-formed body having conductivity, in which a large number of conductive powders (including layered ones) are formed, and the conductive powder agglomerates each other and / or These and the conductive powder are linked in a network to form a conductive network structure. In order to form a lump of conductive powder, a small cylindrical substrate such as a tubular film 1, a curled film 2, and a spiral film 3 as shown in FIG. 1A is used. That is, as shown in FIG. 1B, a conductive powder is attached, filled or filled on the inner and outer peripheral walls of the small cylindrical substrates 1 to 3 (any one or several of them) via a binder. The mixing allows the conductive powder 4 to enter the inside of the small cylindrical substrates 1 to 3.

When the small cylindrical substrates 1 to 3 filled with the conductive powder are pressurized, both ends of the cylindrical film 1, or both ends of the curled film 2, the spiral film 3, and the cuts are formed. Then, the conductive powder 4 is extruded into a powder mass. This conductive powder mass is used as a binder (matrix)
A large number of them are formed therein to form a press-formed body. In addition, the conductive powder attached to the inner or outer peripheral wall of the small cylindrical substrates 1 to 3 or the conductive powder sandwiched between the small cylindrical substrates 1 to 3 comes in contact with each conductive powder mass. Thus, a network structure connected in a network is formed.

Hereinafter, the small cylindrical substrate, conductive powder, binder, and the method of forming the pressed body used in the production of the pressed body will be sequentially described in detail.

Various types of small cylindrical substrates can be applied. As shown in FIG. 1A, conductive powder can be contained in a hollow interior, and can be extruded by applying pressure. Any shape can be used. For example, it may be a cylindrical shape such as a cylindrical shape, a curl shape having both ends opened, a spiral shape, a spiral shape, or a bag shape having only one open end. If necessary, a material having pores formed on the surface of a small cylindrical substrate may be used. The material of the small cylindrical substrate is not particularly limited as long as it has plasticity or elasticity (including flexibility) when pressed, but is made of a thermoplastic resin or a thermosetting resin and has elasticity. Is preferred. For example, when a commercially available product is used, a product obtained by cutting a cylindrical beverage straw can be used. The size of the small cylindrical substrate is not particularly limited. For example, when used as a raw material for a building material board, it is cylindrical and has an inner diameter of 1 to 5 mm and a thickness of 0.2.
It is preferable to cut a piece having a length of 0.5 mm from a piece having a length of 0.5 mm.

Further, the small cylindrical substrate is disclosed in Japanese Patent Application No. Hei.
It is also preferable to use a waste magnetic tape such as a video tape and a cassette tape disclosed in Japanese Patent No. 174742.
This is because when these magnetic tapes are cut or crushed to a length of 1 to 50 mm and heated at 100 to 200 ° C., a difference in thermal expansion occurs between the base material of the tape and the magnetic layer, and the magnetic tape contracts in a curl shape.

If the length of the small cylindrical base material is less than 1 mm, it is difficult to form a network structure by pressurized and extruded conductive powder mass. In addition, when using a cylindrical shape, if the length exceeds 50 mm, the network structure becomes large, and it becomes difficult to form a stable conductive network by kneading with a binder and uniform pressing.
It is not desirable to use a pressed body as a building material board. In order to improve the adhesion of the conductive powder, it is desirable to roughen the surface of the small cylindrical substrate. If the inner diameter of the base material is less than 1 mm, the conductive powder hardly enters the inside. If the inner diameter exceeds 5 mm, the ratio of voids inside increases, leading to a decrease in strength after pressure molding, which is not preferable. If the thickness of the small cylindrical substrate is less than 0.02 mm, the material is weak,
The small cylindrical substrate is easily damaged at the time of kneading or pressing, and if it exceeds 0.5 mm, it is difficult to extrude the conductive powder from the substrate by pressing, which is not desirable.

As the conductive powder, various powders such as metal powders such as gold, silver, copper, iron, aluminum and stainless steel, graphite, nickel, carbon black and ferrite can be used. Among them, expanded graphite is desirable because excellent conductivity can be obtained with a small amount. The fineness of the expanded graphite is not particularly limited, but is preferably from 0.04 to 0.06 g / cc in bulk density.

The binder is a resin such as polyurethane, melanin, epoxy, phenol, urea, or acrylic, or a rubber such as latex, and it is necessary to use a material that can be cured and molded at room temperature or by heating. However, the binder may be used in any state of liquid and powder.

The mixing ratio of the small cylindrical substrate, the conductive powder, and the binder is preferably 5 to 70 parts by weight of the conductive powder and 3 to 70 parts by weight of the binder with respect to 100 parts by weight of the small cylindrical substrate. If the conductive powder is less than 5 parts by weight, sufficient conductivity cannot be obtained. If the amount exceeds 70 parts by weight, the strength of the press-formed body is reduced. Incidentally, a desirable ratio in the expanded graphite is:
5 to 20 parts by weight. If the binder is less than 3 parts by weight, sufficient strength cannot be obtained. If the amount exceeds 70 parts by weight, it becomes difficult to form a conductive network structure, and the conductivity decreases.

Next, a method of manufacturing a press-formed body according to the present embodiment will be described.

(1) Method 1 A small cylindrical base material cut to a predetermined size, a conductive powder and a binder are kneaded at a predetermined mixing ratio. In this case, it is preferable to first knead the small cylindrical substrate and the binder, then add the conductive powder and knead again. By this kneading, the conductive powder or a mixture of the conductive powder and the binder is filled to some extent in the inside (hollow portion) of the small cylindrical base material. The kneading time is preferably 3 minutes or more. If the time is short, the conductive powder and the mixture will not fill the inside of the small cylindrical substrate.

(2) Method 2 A conductive powder or a mixture of a conductive powder and a binder is filled in a small cylindrical base material which has been cut to a predetermined size in advance, and the remaining amount is determined based on the predetermined mixing ratio. The conductive powder and the binder are uniformly kneaded. In this case, the kneading order and the kneading time are not limited.

Next, the kneaded material obtained by the method 1 or 2 is put in a mold and subjected to pressure molding. Although the type of the mold is not limited, for example, a nonwoven fabric bag 6 as shown in FIG.
Is preferred in forming a conductive network structure. The nonwoven fabric bag 6 shown in FIG. 2A is made of polyester, the size of the bag is 2050 mm in depth depth a and 1000 mm in width b, an opening 7 is provided on one side, and the other bottom is sewn. As shown in FIG. 2B, a mixture of the small cylindrical base material, the conductive powder and the binder is filled into the nonwoven fabric bag 6 through the opening 7, and the opening 7 is sealed as shown in FIG. 2C. Thereafter, as shown in FIG. 2D, the mixture is pressure-formed by a hot press 8 together with the nonwoven fabric bag 6.

The pressure molding may be either normal temperature pressing or warm pressing (hot pressing). The pressure may be such that the conductive powder or the mixture of the conductive powder and the binder filled in the small cylindrical substrate can be sufficiently extruded. When a curled discarded magnetic tape shrink piece is used as the small cylindrical substrate, it is preferably about 5 to 10 N / mm ² . The heating temperature for hot pressing is 10
0-200 ° C is preferred.

For example, as a small cylindrical substrate, a length of 20 m
m of curled waste magnetic tape shrinkable pieces of
A hot-pressed mixture of 30 to 50 parts by weight of urea resin with respect to 00 parts by weight has a bending strength of 3 N / m.
Since as high as m ² or more, it can be used as building boards as insulation combined formwork panels. The press-formed body obtained by pressing is cut to an effective maximum width. Then, as shown in FIG. 2E, for example, 9
It is cut into a board 9 of 10 mm × 1820 mm. Since this press-formed body forms a conductive network structure by the conductive powder mass extruded at the time of pressurization, it shows high conductivity. Therefore, it can be used as a building wall material, a floor material, a roof material and the like as an electromagnetic wave shield panel member.

As described above, the press-formed body of the present embodiment has high bending strength by being formed by hot pressing, and can be used as a conductive or electromagnetic wave shielding building material board. When the small cylindrical base material has high elasticity, voids are formed inside the small cylindrical base material after pressurization, so that effects such as light weight, heat insulating properties, sound absorbing properties, etc. are generated, and conductivity, electromagnetic wave shielding properties are obtained. In addition to the above, it is possible to manufacture a board having these features. in this case,
The bulk density is preferably 0.4 or more.

FIG. 3 shows a photomicrograph of the pressure-formed body having conductivity in the present embodiment. This press-formed body is obtained by filling the above-mentioned curled video tape with expanded graphite. The same thickness at the center of the photo, the curled one is crushed and the one that extends in layers is the video tape, and the lump extruded from the curl cut is the conductive powder lump. is there. The portion surrounded by the video tape and the conductive powder mass is a void.

As described above, the conductive powder mass extruded from the inside of the video tape to the outside and the bonding between the conductive powder masses are combined with the conductive powder and the binder adhered to the surface portion of the curled video tape. The contained conductive powder is
They form a network and are chained and formed in a pressure-formed body. This network structure effectively shields the electromagnetic waves.
Therefore, as described above, it is possible to obtain a press-molded article having high electromagnetic wave shielding properties without using a conductive fiber or a conductive wire mesh which has been conventionally used.

[0027]

【Example】

(1) Material Small cylindrical base material Heat treatment at 100-200 ° C, and use magnetic tape (TD
(Company K) curled pieces with a length of 5 to 15 mm or less. B. A commercially available polyvinyl chloride straw having an inner diameter of 1 to 5 mm cut into a length of 5 to 20 mm. Expanded graphite (Nippon Kasei) b. Ferrite powder (Toda Kogyo) Binder X. Urea resin (Dainippon Ink and Chemicals) Y. Phenolic resin (Sumitomo Durres) Non-woven fabric Polyester (Toray) Equipment Mixing equipment (Einrich)

(2) Manufacture of press-formed body Kneading a. Method 1 With the composition shown in Table 1, 20 mm x 910 mm x 1820 m
Each press-formed body having a size of m was manufactured. In the kneading, first, the small cylindrical base material and the binder were kneaded for 3 minutes, and then the conductive powder was added and further kneaded for 5 minutes. b. Method 2 With the composition shown in Table 1, 20 mm x 910 mm x 1820 m
Each press-formed body having a size of m was manufactured. The conductive powder was filled in the small cylindrical base material, and if there was any remaining conductive powder in order to further obtain the surface adhesion effect at each mixing ratio, the conductive powder and the binder were kneaded for 5 minutes. 75 liters of the kneaded material obtained by the above method 1 or method 2 are put into a nonwoven fabric bag having a size of 1000 mm × 2050 mm, and a temperature of 150 ± 5 ° C. and a pressure of 10 N / cm ² are added to the nonwoven bag.
Hot pressing was performed for 0 minutes, and the four sides of the obtained plate were trimmed to complete a press-formed body.

(3) Method for evaluating physical properties Confirmation of formation of conductive network structure Microscopic observation with a SEM manufactured by Hitachi, Ltd. and confirmation of formation of a conductive network structure were performed. The results are shown in Table 1 and an example is shown in FIG. Test Examples 1 to 17 in Table 1 relate to the present invention, and Test Examples 18 to 20 are comparative examples.

[0030]

[Table 1]

Table 1 shows the results obtained by the Advandes method. Bending strength Table 1 shows the results of the same test conducted in accordance with JIS K-7221.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

For example, in the above-described embodiment, the conductive powder is put into all the small cylindrical substrates and pressurized in order to form the conductive powder mass at both ends of the small cylindrical substrate. The size of the network structure may be controlled by mixing, in various proportions, a material in which conductive powder is adhered only to the surface of a small cylindrical base material, or a material in which conductive powder is placed inside. In this case, the non-cylindrical material having the conductive powder adhered only to the surface may be of any shape.

[0034]

According to the present invention, it is possible to obtain a pressure-molded article having a high electromagnetic wave shielding property without using conductive fibers or conductive wire netting, and without laminating magnetic layers. In addition, if the non-woven fabric is used as a mold at the time of molding, the pressed molded article can correspond to various shapes such as a curved surface. Further, by hot-pressing, a material having a high bending strength can be obtained, and therefore, its utility value as a building material board is high. It is also very economical to use a waste material such as a waste magnetic tape to obtain a small cylindrical substrate.

[Brief description of the drawings]

FIG. 1A is a perspective view of a small cylindrical base material used for manufacturing a press-formed body according to an embodiment of the present invention. B is a perspective view showing a state where conductive powder is filled in the small cylindrical base material.

FIG. 2A is a plan view of a non-woven bag for filling a mixture of a small cylindrical base material, a conductive powder, and a binder for manufacturing a press-formed body according to an embodiment of the present invention.
B is a side view showing a state where the nonwoven fabric bag is filled with the mixture. C, after filling the mixture in the nonwoven bag,
It is a side view which shows the state which sealed the nonwoven fabric bag. D is a side view showing that the non-woven fabric filled with the mixture is hot-pressed together with the non-woven fabric. E, after pressing the non-woven bag,
It is a perspective view which shows the board which is the cut pressure molding.

FIG. 3 is a diagram showing a micrograph of a press-formed body manufactured according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical film 2 Curled film 3 Spiral film 4 Conductive powder 6 Nonwoven fabric bag 7 Opening 8 Hot press 9 Board

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29K 105: 26 (72) Inventor Kensuke Kasahara 2-6-2 Higashikanda, Chiyoda-ku, Tokyo Fuji Chemical (72) Inventor Toshiya Nagai 2-6-2 Higashi Kanda, Chiyoda-ku, Tokyo Fuji Chemical Co., Ltd.

Claims (6)

[Claims] 1. A press-formed body comprising a conductive powder, a small cylindrical base material, and a binder for binding the conductive powder, and extruded from the small cylindrical base material by pressurization during pressure forming. The formed conductive powder mass or the mixture mass of the conductive powder and the binder is scattered singly or in contact with each other, and / or the conductive powder mass or the mixture mass and the surface of the small cylindrical substrate The conductive powder attached to each other is in contact with each other to form a conductive network structure linked in a network and has a volume resistivity of 10%.
^A pressure-formed body having a conductivity of ² Ω · cm or less. 2. The compounding ratio of the conductive powder, the small cylindrical substrate, and the binder is 5 to 70 parts by weight of the conductive powder and 3 to 70 parts by weight of the binder with respect to 100 parts by weight of the small cylindrical substrate. Item 2. A pressure-formed body having electrical conductivity according to Item 1. 3. The small cylindrical substrate is cut or crushed to a length of 1 to 50 mm of a waste magnetic tape such as a video tape or a cassette tape, heated at 100 to 200 ° C., and shrunk in a curl shape. The pressure-formed body having conductivity according to claim 1 or 2, wherein the pressure-formed body has electrical conductivity. 4. The pressure-formed compact having conductivity according to claim 1, wherein the conductive powder is expanded graphite. 5. The binder according to claim 1, wherein the binder is a resin such as polyurethane, melamine, epoxy, phenol, urea, or acrylic, or a rubber such as latex, and is a material that can be cured and molded at room temperature or by heating.
5. A pressure-formed body having electrical conductivity according to 4. 6. The pressure-molded body having a bending strength of 3 N / mm.
6. The pressure-formed body having conductivity according to claim 1, which is ² or more.