JPS63126299A - Molded article for shielding - 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 (Field of Industrial Application) The present invention relates to a molded product for shielding, particularly a molded product for electromagnetically shielding electric wires.

(Prior art and problems to be solved by the invention) Conventionally, metal tubes have been used to shield electric wires, but metal tubes have drawbacks such as being difficult to bend, heavy, and difficult to cut. , there is a need for more convenient and easy-to-use materials. The present invention provides a novel shield molding that does not have the drawbacks of the metal tubes described above, is easy to use, can be manufactured efficiently, and can be freely shaped and sized.

(Means for Solving the Problems) The molded product for wire shielding of the present invention is made of a thermoplastic polymer in which a conductive filler is dispersed, and in which conductive wires that are continuous in the length direction are embedded. In the molded product, whether the molded product is (a) in the form of a hollow tube capable of storing electric wires therein or in the form of a hollow tube that can be opened and closed; or (D)
It is characterized by being in the form of a sheet or tape that can be used by attaching an electric wire = t-S.

FIGS. 1 to 5 are cross-sectional views of molded shields showing specific examples of the present invention, in which the shaded area (1) is the shield layer, that is, the polymer containing the conductive filler.

Figure 1 shows a thermoplastic polymer (1
), and one conductive wire (2) that is continuous in the length direction is embedded. The hollow part (3) is a space for accommodating the conducting wire to be shielded.

Figure 2 shows two hollow parts (3a, 3a,
3 b), and two (2) continuous conductors in the length direction.
a, 2b) and a protective layer (5) on the outside.

FIG. 3 shows an example of a tubular molded product that can be opened and closed, and is a convenient example in which electric wires can be easily loaded into and taken out from the hollow portion (3). FIGS. 4 and 5 show examples of sheet-like or tape-like molded products, which can be used by being wrapped around electric wires or the like.

FIG. 6 is a perspective view showing an example of the use of the tubular molded product as shown in FIG. 1, in which eight electric wires (4) are inserted and stored. FIG. 7 shows an example of the use of an openable and closable tubular product as shown in FIG. 3, and seven electric wires (4) are housed inside. The joint portion may be left as it is, or may be bonded by an appropriate method.For example, the joint portion may be coated with an adhesive, covered with a polyethylene tape, etc., and the coating may be peeled off for bonding (self-adhesive type). Alternatively, it may be tied with thread, wire, etc., or may be wrapped with adhesive tape. Similarly, for example, two semicircular moldings can be put together to form a cylindrical object, which is also considered an openable and closable tube and is as convenient as the molding shown in Figure 3. . FIG. 8 shows an example of the use of the tape-shaped molded product shown in FIG. 4, in which the tape-shaped molded product is wound in a helical shape around seven electric wires (4). As described above, the molded product of the present invention can be used in a manner such as storing an electric wire to be shielded in the hollow portion, or wrapping or winding the electric wire with a sheet-like or tape-like material.

The longitudinally continuous conductor (2) is of great importance.

In other words, the shielding molding is connected to sockets, terminals, grounding parts, and other metals at the ends and other parts by soldering, etc., but by soldering to the conductor (2), it is possible to connect with high strength and low connection resistance. You can.

If this RvA (21 is not available), it is impossible or extremely difficult to solder directly to the shield layer. There are also methods of connecting with conductive adhesive, wrapping metal wires, or sandwiching them between metal plates. Both of these methods are troublesome and inefficient, and have the drawbacks that the contact becomes uncertain, tends to come off easily, and increases the contact resistance.

Another effect of the conductive wire (2) is to reduce the longitudinal resistance of the shielding layer and increase its electrical conductivity, thus increasing the shielding effect. A mixture of a thermoplastic polymer and a conductive filler can be rendered thermoplastic by appropriate mixing ratios and mixing methods. However, in a range that provides good thermoplasticity (melt fluidity), although there is a shielding effect, the electrical resistance tends to be higher than that of metals, and the shielding effect tends to be low. Further, when the shield portion is used as a conductor on the negative side of an electric signal, for example, if the resistance of the shield layer is large, the attenuation of the electric signal becomes large over a long distance. The shielded wire including the conductor (2) of the present invention is easy to solder at the connection part (soldering to the conductor (2)), has low grounding resistance and transmission resistance, and has a high shielding effect, and has a high shielding effect, and is highly effective for signal transmission. It has the excellent feature of little loss. For example, it has a volume resistivity (hereinafter referred to as specific resistance) of 1 Ω and a resistance of YK Ω per 1 m. By burying one copper wire with a diameter of 0.3 mm in this, the resistance per meter can be reduced to 0.3 Ω or less, greatly strengthening the shielding effect and reducing transmission loss.

FIG. 2 shows an example in which a protective layer (5) is provided on the outside of the shield layer (1), and as the protective layer, for example, various polymers or knitted fabrics can be used as required.

The number of conducting wires (2) may be one or multiple (for example, 2-10, especially 2-5). It may be a single wire, or it may be a bundle of many wires or a twisted wire. The cross section may be circular or non-circular, and may be ribbon-shaped, tape-shaped, triangular, star-shaped, or other arbitrary shapes. As the material of the conducting wire, metals, alloys, etc. used for conducting wires are suitable. In terms of transmission loss, shielding ability, and grounding resistance, the electrical resistance of the conductor (2) is preferably equal to or lower than that of the shield layer. That is, the resistance of the conducting wire (2) with a length of 1 m is equal to or less than the resistance of the shield layer with a length of 1 m, preferably 172 or less, and most preferably 115 or less. For example, 5! L
The resistance per meter of wire (2) is preferably IKΩ or less, and 1
00Ω or less is particularly preferable, and 1Ω or less is most preferable.

Shield layer f1. l must be conductive. Generally, the lower the specific resistance, the better the shielding ability.

The specific resistance must be 1000Ω・cm or less, and 100Ω
・cm or less is preferable, and 1Ω·cm or less is most preferable. The thickness of the shield layer is arbitrary, but usually 0.3 to 10
Those with a diameter of about mm, particularly about 0.5 mm to 5 mm, are often used.

The conductive fillers used in the shield layer include short metal fibers,
Examples include metal fine particles, carbon fibers, carbon blanks, etc., but metal fibers are most preferred in terms of shielding effect. The metal fiber has a diameter (D) of 0.1 to 300 μm,
Especially about 1 to 200 μm, length L) 10 μm to 20
About mm, especially about 0.1 to 10 mm, L/D=100
The above are preferred.

The cross section of the metal fibers may be circular or non-circular. Non-circular shapes are often preferable because they have lower contact resistance and better shielding effects. A longer length is preferable from the viewpoint of conductivity and shielding effect, but from the viewpoint of moldability it is preferably 10 mm or less, particularly preferably 5 mm or less, and most preferably 3 mm or less. Diameter 0 for 4-shaped
．． 1 mm or less, especially 50I! m or less, L/D is 5~
100 is often used. Thickness O in flake form
, 1 to 100 μm, and a length of about 0.1 to 3 mm is preferably used. Examples of metals forming the metal fibers and metal particles include copper, zinc, tin, iron, aluminum, silver, nickel, and alloys containing these ingredients, such as brass, brass, stainless steel, and duralumin. Of course, in addition to the above materials, any material can be used in the present invention as long as it has excellent R conductivity, is chemically stable, has no toxicity, and can be molded into a fibrous or fine particle shape. The mixing ratio varies depending on the shape, size, mixing method, etc., but for fibrous, flake, and acicular fillers, the volume mixing ratio is 5 to 50%, especially 5 to 30%.
, most often from 5 to 20%, which often provides adequate resistivity and fluidity. For fine particles such as granular fillers, favorable results are often obtained at a volumetric mixing ratio of 5 to 60%, particularly 10 to 40%.

Another example of a conductive filler is carbon fiber. As the mixing ratio increases, the specific resistance decreases, but the melt fluidity tends to decrease. Appropriate resistivity and fluidity are often obtained at a carbon blank weight mixing ratio of 5 to 40%, particularly 15 to 35%.

In addition to the above, examples of conductive fillers include carbon fibers and semiconductor particles. Carbon fibers have the disadvantage of being easily folded during mixing, but for example, carbon fibers with a diameter of 10 μm to 15 μm and a length of 0
．． 5-40% (weight) of 5-5 mm, especially 1
Appropriate specific resistance and fluidity can often be obtained by mixing 0 to 30%. Glass fibers having this other-electroconductive film (metal coating, etc.) can also be used.

Further, inorganic semiconductor fine particles such as tin oxide, zinc oxide, indium oxide, copper sulfide, and particles of titanium oxide, silica, zinc oxide, and the like having a conductive film of metal or semiconductor can also be used. Of course, it is also effective to use a combination of two or more of the above various conductive fillers (for example, fibrous and granular ones).

Generally, the conductive effect of R-conducting fillers is most effective when they are fibrous.
The second type is needle-shaped, and granular ones tend to be inferior. (Even if it is granular, it has good R-electrification properties if it has good chain-forming properties.) Therefore, it is necessary to mix a relatively large amount of granular material, which tends not only to have poor fluidity but also to make the product less flexible. .

That is, from the standpoint of imparting excellent flexibility to the product (molded product), fibrous fillers in the form of dragon are preferred, followed by those in the form of needles and flakes.

The thermoplastic polymer forming the shield layer is polyamide,
Polyester, polyurethane, polyolefin, polyvinyl, polyether, polycarbonate and all other thermoplastics can be used. In addition, from the viewpoint of the flexibility of the product, those mixed with or copolymerized with a plastic component and those exhibiting rubber-like elasticity are particularly preferred. For example, vinyl chloride containing a plasticizer, thermoplastic polyurethane (elastic) natural rubber, various synthetic rubbers, block copolymer elastomer ethylene/vinyl acetate copolymer, acrylonitrile/butadiene/styrene copolymer, vinyl chloride/vinylidene chloride Copolymers, polyal; block copolymers of 1-lene ethers (e.g., polyethylene oxide, boebutylene oxide, etc.) and polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, etc.); similarly polyalkylene ethers and polyamides (e.g., nylon 6);
, nylon 66, polyhexamethylene terephthalamide, etc.). Of course, stabilizers, fluidity improvers, dispersants, colorants, etc. can be added as a subsidiary.

The above-mentioned thermoplastic polymer can be melt-molded by utilizing its thermoplasticity, and if necessary, can be cross-linked (for example, cross-linked by radiation) after molding. Of course, heat resistance and strength can be improved by crosslinking or the like.

The shield molding of the present invention can be efficiently produced very easily by melt molding. For example, the shielding layer component (a mixture of conductive filler and thermoplastic polymer) and optionally the protective layer component (e.g. a thermoplastic polymer such as vinyl chloride) are melted separately and placed together with the conducting wire (e.g. copper wire). It is possible to extrude the material from the extrusion die while removing the material and mold it at the same time. In the case of a structure having a space as shown in FIG. 2, the space can be formed by supplying a gas such as nitrogen or air during extrusion, if necessary.

(Effects of the Invention) The shield wire of the present invention can be used in ordinary audio equipment, high frequency equipment, televisions and other ultra-high frequency equipment, computers and other light electrical equipment, connection lines thereof, communication lines such as telephones, other light electrical applications, and power cables. It can be used in an extremely wide range of applications, including other high-voltage applications. especially? j [It is possible to easily store, open and inspect complicated multi-line cables, and because it is lighter and more flexible than conventional metal pipes, it is suitable for use in moving objects such as aircraft, automobiles, ships, small equipment, and homes. It is extremely useful in fields such as electrical equipment, signals, communications, computing, and measurement.

(Example) The present invention will be explained below with reference to Examples.

Example 1 It has a triangular cross section with a diameter of approximately 50 μm, contains 15% (volume ratio) of brass fibers with a length of 2 mm, and has a specific resistance of 0.3 Ω・cm.
The conductive polymer CPI is made from soft (plasticizer-containing) vinyl chloride.
shall be. A copper wire with a diameter of 0.5 mm is used as the conductor (2), and C
A shield tube STI as shown in FIG. 1 was obtained by melt extrusion at 210° C. using PI for the shield layer fil. The outer diameter of STI is 12 mm, the inner diameter is 8 mm,
The thickness of the part where the conducting wire (2) is buried is 3 mm.

For comparison, a similar shield tube obtained without embedding the conducting wire (2) is designated as Sr1. The shield layer of s"ri exposes the copper wire (2) at both ends and can be easily soldered, but
The shield layer of r1 could not be soldered. The resistance of STI with a length of 1 m was 0.02Ω, but that of SW2 was 18Ω.

A vinyl chloride-coated electric wire (resistance 0.01 Ω per meter) is passed through the 30 m long STI, and a microphone (dynamic type) is attached to one end of this electric wire and one end of the conductor of the shield tube STI. Connect the conductor and ST
Connect the other end of the lead wire of l to the input terminal of the loudspeaker amplifier 11 h'
t (the S T I conductor was grounded), and it worked well as a loudspeaker without any noise. Sr1 in one direction
(However, the Sr1 shield layer is connected with conductive adhesive) A considerable amount of noise (so-called induced hum) was generated, and the microphone's intensity decreased, which is probably due to transmission loss).The S/N ratio decreased. His voice was so low that it was difficult to hear him. Next, when two electric wires were placed in Sr1 and the shield layer was grounded on the amplifier side, almost no decrease in sensitivity was observed, but some noise remained and the shielding effect was insufficient.

Example 2 The CPI of Example 1 was used, and the conductor (2) had a diameter of 0 and 1.
Using two strands of 12 7 mm copper wires, a shield tape ST3 having a thickness of 1 mm, 3 cm, and a cross section as shown in FIG. 5 was obtained by extrusion molding. Wrapping ST3 around a bundle of wires in the multiplier is done by grounding the conductive wire (2) to prevent both noise generation (electromagnetic wave radiation) and noise mixing into the signal (induction, etc.). The effect was recognized.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views showing specific examples of the molded product of the present invention, and FIGS. 6 to 8 are perspective views showing examples of use of the molded product of the present invention. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) A molded product for a wire shield made of a thermoplastic polymer with a conductive filler dispersed therein and in which a conductive wire that is continuous in the length direction is embedded, the molded product (a) housing the wire inside; A molded article for an electric wire shield, characterized in that it is in the form of a hollow tube that can be opened and closed, or (b) in the form of a sheet or tape that can be used by being wrapped around electric wires.