JPS59140281A - Electroconductive gasket - 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 The present invention relates to conductive gaskets, and more particularly to gaskets that prevent electromagnetic interference (Em') to electrical devices inside an enclosure.

EMI gaskets are used to seal all connections between mating surfaces where it is necessary to prevent the penetration of electromagnetic or electrostatic energy. In addition to the need in this regard, the gasket is often required to also act as a weatherproof seal between mating surfaces. Conventional methods for achieving the above requirements use an elastic material with conductive particles encapsulated throughout its volume, either as a elastomer-loaded conductive granule or as a wire across a gasket.

However, this type of gasket is associated with numerous problems. Regarding gaskets containing metal wires, there is the issue of whether electrical and mechanical properties are compatible from the perspective of corrosion resistance, and the problem is that deformation of the wires shortens the life of the gasket and causes loss of contact between mating surfaces. occurs frequently. To obtain good electrical properties, it is necessary to load conductive particles on both sides. Obtain bidirectional conductivity (such that the conductivity in the plane perpendicular to the mating plane is typically 50 s/m and in the plane at said mating plane 90' 00 s/m). A common optical material used for this purpose is silver. However, the use of silver means that the gas kerato is expensive and relatively heavy, making it unsuitable for use in aircraft doors, where the present invention may be readily applicable. When carbon-based granules are used, the interference resistance of the granules (typically O-0.4 s/m in the plane perpendicular to the mating plane and 4 s/m in the plane of the mating plane) increases. Because it is thick, its conductivity is poor.

All types of gaskets are composed of electrically conductive elements, either in the form of granules, flakes or wires. In the case of wires, because of the alignment method in the elastomeric matrix, contact can only occur in one direction, so both ends of the wire must be in contact with their respective mating surfaces in order to function. When using conductive elements in the form of particles or flakes for the conductive tracks to be constructed, the conductive elements must be in contact with other conductive elements in at least two places so that current can flow therethrough. The probability of contact at a point increases with an increase in the lateral-to-lateral ratio of the conductive element.

Because conductive elements in the form of flakes or granules have a very low coefficient of inertia, they must be highly loaded to form conductive tracks.

However, it has been found that when long fibers with a high side-to-side ratio are used, conductive tracks can be easily constructed even at low loadings.

Therefore, the present invention provides an FJ for electrical equipment inside an enclosure.
A conductive gasket for preventing JI interference, the conductive gasket being formed from an elastic material and having a dedicated (orbital) track within the gasket, the track having a cross-to-lateral ratio and made of conductive fibers. do.

The present invention is characterized in that an elongated inner mandrel is surrounded by an elongated outer mold, and the space between said mandrel and the mold is filled with a mixture of an elastic material, a hardening agent, and carbon fibers, said carbon fibers being preferably attached to the mandrel. The mixture is cured by being oriented along the length of the mandrel, the outer mold being removed, and the cured mixture wJ being cut in a direction perpendicular to the longitudinal direction of the mandrel. All conductive gaskets that can be obtained
provide law.

In a preferred embodiment, the fibers are carbon fibers, preferably with a metal coating, and the gasket is provided with upper and lower conductive holes.

Embodiments of the invention will now be described with reference to the accompanying drawings.

The present invention may be coated with a metal (such as silver, tin, nickel or copper) as a method of increasing fiber-to-fiber contact and improving conductivity due to the lower side-to-side ratio. Carbon fibers are used, which can provide very good excretion values (up to 20,008 m/m for a loading of 5% carbon fibers) in the plane of the total interpolation plane.
-10,000 (only 5 s,/m for 5% carbon fiber loading) does not provide a sufficiently good conductivity in the plane perpendicular to the phase plane.The reason for this is that the mixing and curing of the gasket This is because, as a characteristic, the fibers themselves are not aligned in the plane of the mating surface.Therefore, it is preferable to carry out a certain pre-treatment on the surface of the rod in order to completely improve the conductivity in this plane.

In the first embodiment, a special surface layer or surface treatment is applied to the mixture of cut fibers and elastic material to improve the electrical conductivity. These surface layers may be made of coated or uncoated knit woven carbon fiber cloth, plain woven carbon fiber cloth, carbon fiber felt, carbon fiber paper, or the like.

Thus providing high conductivity values, for example knitted carbon fiber fabrics with @'l coated fibers have a conductivity of 1 B, 6 s/ in the direction perpendicular to the plane at the mating plane.
m, in the plane of the mating plane it provides a conductive value of 12158 ha. The gasket according to the present invention is lightweight and relatively inexpensive compared to a gasket loaded with silver particles, and also has excellent electrical and mechanical properties in terms of corrosion due to the use of carbon fiber synthetic material8. .

In this type of gasket, the frugality of the fibers used is important. For good mixing, the fiber feldspar should be approximately
1J or less is preferable, but it is preferable that the amount of debris is not large enough to completely lose the advantage of the conventional ratio of the fibers. A preferred minimum length of 172 mm has been found to give a good-looking sweetfish.

A preferred range of fiber diameters is between 5 and 20 microns, with a diameter of 7 microns found to provide adequate results. However, in special applications, fibers up to 200 microns in diameter can be used. A very thin plating layer of 1 to 4 microns is applied to the fiber diameter.

The blending of fibers, elastomeric materials and curing agents is practically essential.

The shorter the mixing time, the better the gasket properties, assuming better distribution of both the fibers and the curing agent. This is because the fibers tend to break during the mixing process, especially when thick elastic materials are used in hard gaskets, such as those used between bolt joint surfaces.

The mixture may also contain a filling powder to impart rigidity to the finished gasket, and optionally a dye if desired to color the finished gasket.

In such cases, the mixing time while the fibers are being used is such that the filler is added before adding hardeners or fibers, to reduce the noise.
Mix the elastic material and dye until well mixed.

In addition to the curing agent, a foaming agent may be added to the gasket so as to form bubbles across its width. Such gaskets are much more compressible than gaskets without bubbles.
).

In the first example of making a gasket truck with a Shore A hardness of 55, the selected elastic material is Sylgard (5YLGARD) 1.
70 and its viscosity is 1500 centivoise and 40
It was between 0.00 centiboise. The elastic material was mixed with a curing agent at a mixing ratio of 1:1, with 7 mm thick carbon fibers added at a Ni ratio of 5%. The mixing time was 5 minutes at a speed of 60 to 120 revolutions per minute. Using the obtained mixture, a gasket having a Shore A hardness of about 55 was made as described below.

In the second example of creating a gasket with a Shore A hardness of approximately 25, the elastomeric material chosen was 'RHORDO'.
R8IL) R,T,V, 581 and its initial viscosity was 20,000 centivoise. This elastic material is 1
Hardener and 7 mm carbon fiber were added in a ratio of 00:3 at 5% by weight and mixed for 6 minutes at a speed of between 60 and 120 beats per minute. The resulting mixture was used to make a gasket as described below.

However, it is also possible to mix fibers of different lengths in a matrix of elastic material, as described above, in order to obtain electrical bonding and electrical properties in a plane perpendicular to the mating plane. The loadings found to be optimal and used to meet the aforementioned conductivity values were between 4 and 7% by weight. For long fibers, it is possible to reduce the loading to 2%, and it is also possible to use additives to load fibers with loadings up to 10%.

There is also the possibility of treating the surface of the gasket by sand blasting or shot blasting. This method removes excess elastic material from the gasket surface,
The fibers are exposed. The fibers may or may not be plated. An alternative to this treatment method is to roughen the inner surface of the mold in which the gasket is made.

This method produces the same result as plastering the surface of the gasket.

The outer surface of the gasket may include a "bleed" cloth that is later torn away to expose the carbon fibers at the surface. Electrical properties vary depending on the fabric's surface finish, thickness, and absorbency. For example, fiberglass or metallized cloth can be used.

The carbon fiber surface layer described above as a paper, cloth or mat can be coated on the mold in its hand-finished state (rather than coating the individual fibers) before being encapsulated in the gasket.

This metal coating holds the V fibers together and further improves electrical contact.

The surface layer can be comprised of carbon fiber coated with various metals on either side of the gasket.

This method provides galvanic compatibility to overcome corrosive effects when opposing structures are gasketed together in order to carry current, e.g. a hatch made of aluminum alloy (e.g. a hatch made of carbon fiber composite material) surrounded by a stem cover. I beg you. In this case) the unplated carbon fiber surface layer of the gasket contacts the synthetic surface, and the tin-plated carbon fiber layer contacts the aluminum surface. In this way, the Luvaney interface is moved to the inside of the gasket, which is not important because water does not penetrate that far.

The interior of the gasket may be filled with other carbon fiber materials in addition to cut fibers. Automotive elements can be constructed in such a way that the majority of the fibers move "through the thickness" to achieve maximum electrical conductivity. Three-dimensional thick materials, ie velvet materials, can be used for such purposes, but must be mixed with a matrix rubber rather than by the mixing method described above.

Carbon fiber fiber optic material can be used to "seal the gasket in place." These consist of a thin layer (usually) of polysulfide rubber that is squeezed onto the surface where the gap filler gun is attached, and this layer is a thin sealing layer that is tightly bonded to each other, such as in aircraft bonded skin panels. form. It is often advantageous for this layer to be electrically conductive, and carbon fiber optical fibers are one way to accomplish this goal.

Due to the inherent stiffness of carbon fiber optical fibers, the material is much stiffer in all dimensions than its parent elastomer matrix.

This inherent stiffness is distributed through the carbon fiber optic in a uniform flow pattern and can have a significant effect on the elastic properties of the material even at relatively low loadings (such as about 5% coulometric). It is possible and necessary. In purchasing tests, the inclusion of carbon fibers in the material creates a material with excellent mechanical recovery, i.e. when the material is deformed by pressure, it rapidly returns to its original dimensions as soon as the pressure is released. indicated that it would return to It has been found that this is also true when the pressure is applied uniformly over the surface of the material or when the pressure is applied locally to only a portion of the material.

A surface layer of carbon fiber material improves this situation with respect to the pressure applied to the surface where the carbon fibers are interposed. Again, this may be due to the inherent stiffness of carbon fiber.
This is also because the material is cohesive in either the cloth or the knitted fabric, thereby distributing the locally applied pressure.

Apart from electrical applications, the advantage of these materials is that they provide a gasket that can withstand high closing forces and recover to its original state once the pressure is released, thereby providing a good recovery when the closing force is reapplied. This means that there is no need to replace the gasket to maintain this condition. Also, if the material had not recovered, electrical contact would be lost, but since the material has recovered, the gasket is electrically conductive in the sense that it provides good electrical contact even when the closing force is reapplied. My shoulders are stiff at all times.

By adjusting the length of the fibers, the width and height of the material, the above properties can be utilized, thereby making the weather resistant seal more efficient, and by making other adjustments, the above properties can be improved.
Can be used for g, m, ■ gaskets and weather-resistant seals.

The method for manufacturing the gasket will be explained below with reference to FIGS. 1 to 4.

Referring to FIG. 1, a mold is shown in which an inner mandrel 10 is surrounded by an outer mold (not shown) and the space therebetween is filled with a matrix 12 of carbon fiber/elastic material. The inner mandrel defines the inner dimension χ of the gasket. The material is fed from one end into the space between the inner and outer molds so that the fibers are aligned in the direction of the arrow. This mass of material is then shaped so that once the apparatus has cooled the material is removed into cuts 14' to obtain gaskets of the desired dimensions. The inner mandrel 10 may be of any shape, from circular to complex, depending on the particular purpose. The same is true for the outer mold (not shown). This method allows the fibers to be oriented at right angles to the plane of the mating surface to which the gasket is to be attached. When the gasket is cut, the edges of the gasket in a plane perpendicular to the mating surfaces are erect. This is because fibers protrude from these surfaces and make electrical contact with the mating surfaces. Various cutting techniques can vary the average length of the fibers protruding from the face of the gasket, thus tailoring it to the final application.

This can be done, for example, by water jet cutting.

There are two alternative ways to create gasket materials by aligning the fibers in the correct direction. The first method is to put the mixture wJ into a shallow mold 2o, in which the heating direction of the fibers is horizontal, and once cured, the material is removed from the mold and its length δ (Fig. 2) By cutting the strip 22 along , it is possible to obtain a strip in which the fibers are in the correct orientation when turned 90 degrees. By directing the mixture of materials through a portion of the mold or by combing the mixture before curing, the fiber orientation is better controlled. The strip and mold #8 can be matched so that the final strip size of the gasket is compatible with the particular application.

The second primary method of obtaining strips of gasket material is to make slices 14 of the material made in FIG. 1, as shown in FIG. Long strips of material are created by cutting in a spiral from the outside to the inside. The cutting and forming parameters can also be tailored to suit the particular application.

It has been found that extremely good conductivity can be obtained even with a low carbon fiber loading rate. The preferred gasket tested included a nickel-plated carbon fiber (5% by weight loading) in a silicone matrix. This gasket has a resistance of approximately 400 s/in the plane perpendicular to the mating surfaces (more than 10 times faster than the best silver-loaded gaskets measured).
It was found that the conductivity was m.

Using the coaxial short fittings proposed in the S, A, E Standard (Muddle at S, A, E Committee AE4 in Sandego, October 8, 1979).

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Figure 4 shows the results of measuring the blocking effectiveness of various filled elastic materials.

In addition, the hardness of the gasket can be adjusted to suit specific applications due to its excellent air resistance and R, E, L, and cut characteristics. This implementation can be accomplished in one of several ways. First, the hardness of the elastic material matrix can be changed, so the gasket made according to the hardness of the elastic material formed in the base material can be made harder, smoother, or softer. The second method is C, which changes the carbon fiber loading rate, although it can result in undesirable gasket electrical properties. A sixth method is to add a filler other than carbon fiber, which has the effect of making the gasket χ harder, such as by applying glue. It is also possible to create a cavity filled with gas to create a gasket with a higher pressure.

If you want to make a hard gasket using hard cricon, if you add a low percentage of silica by weight and maximize the carbon fiber loading, the gasket will have good creep resistance and have a Shore A hardness of about 75 can be achieved.

Even at high loading rates, the gasket has advantages, especially in weight, compared to silver-loaded gaskets. This is extremely useful for applications where weight is important, such as the space industry or equipment that can be carried by humans.
There is C.

By having sufficient elasticity, the gasket also acts as a weatherproof seal. However, if the hardness of the gasket is too thick, the closing force will need to be relatively large. Since portions of the gasket are likely to be exposed to the outside environment, it is important that the mechanical and electrical compatibility of the gasket closely match that of the mating surfaces. This means that
As previously mentioned, this can be accomplished by plating the carbon fibers with a suitable metal that is compatible with the material forming the mating surfaces. For carbon fiber composites, plating is not necessary and unplated carbon fibers can be used.

It is also possible to use other elastic materials as an alternative to the 7-recon rubber. For example, fluorosilicone or nitrile rubber can be used. The result of this is that it provides the gasket with much more robustness against the effects of agents that may be present in the external environment of the aircraft, for example.

In addition to being used as tetraconducting gaskets, these materials also have potential for use as thermally conductive gaskets. The four-dimensional properties of the parallel plating and carbon fiber station are also useful in transferring heat to the appropriate heat sink.

[Brief explanation of the drawing]

Figure 1 shows the inner mandrel and the gasket taken out from the mandrel. Figure 2 shows the second molding method. Figure 6 shows the sixth molding method. FIG. 4 and FIG. 4 are graphs showing the effective stock versus frequency. In Figure 2, 10...P'91111 mandrel 12...Material matrix 14...Slice 20...Tongue-
Rudo 22... Obi agent Haru Asamura Continuing from page 1 Priority claim @ April 26, 1983 ■ United Kingdom (GB
)■8311332 0 Inventor William George Howell 7 Northants Green Two-Tone Cycamo Drive, United Kingdom @-R Akira Nicolas James Logie Pax West Lycomb Portway, United Kingdom Drive 4 Mr. Commissioner of the Japan Patent Office 1, Display of the case 1982 Patent No. 201161! 2. Name of the invention: Conductivity is Schedule 3. Relationship with the case of the person making the amendment: Patent applicant address/name: Fledge Overseas Limited (name) 4. Agent 5: Date of amendment order (Showa year/month) 1" 8. Contents of the amendment. As shown in the attached sheet, engraving of the specification (no change in content) Procedures' written amendment (method) Showa (2nd month, δ/Sunset) Mr. Commissioner of the Japan Patent Office 1, Indication of the case Showa, β year patent application No. 7 No. 2, Title of the invention 3, Person making the amendment 1 Relationship with patent applicant address 4, agent 5, date of amendment order 1920, month η day 6, Number of inventions increased by amendment 7, subject of amendment

Claims (1)

[Claims] 1) A conductive gasket for preventing electromagnetic (EM) interference with a gas filter inside a sealed body, the gasket being made of an elastic material and having a horizontal and vertical ratio. The guide 1iE
1. A conductive gasket characterized in that a conductive track formed from sterile fibers exists inside the gasket. 2. A conductive gasket according to claim 1, wherein the conductive fibers having both horizontal and vertical dominant ratios are secondary fibers. 3) A conductive gasket according to claim 2, in which carbon fibers are coated with a metal. 4) A conductive gasket according to any one of Claims 1 to 6, in which conductive holes are provided on both sides of the gasket in order to improve the performance. 5) Any one of claims 1 to 4 reeds
A four-ridge gasket according to item 1, wherein the diameter of the secondary fiber is in the range of 5 to 20 microns, and the length is in the range of 1/2 to 10 mm, where t-=i. 6) Any one of claims 11 to 5
[Patented 4-ton gasket. 7) Any one of claims 2nd to 6th song
2. A conductive gasket according to item 1, characterized in that the charcoal-$ fiber constitutes 4 to 7% of the gasket in terms of weight ratio. 8) In the gasket according to any one of claims 2, 6, 5, 6, or 7, the excess 9# injection material is removed, and carbon, I Both sides of the fibers: A conductive gasket characterized by sand blasting or shot blasting the entire area around the four holes of the gasket to expose the fibers. 9) In the gasket according to claim 4, the temperature is
, t'#a, a conductive gasket in which the conductive layer is made of metal-coated paper, cloth, or mat. 10) In the gasket as claimed in claim 6, the carbon fibers coated with metal are used on both sides of the gasket to overcome the problem of carbanic compatibility. Gasket. 11) In the gasket according to claim 1, fibers having a high horizontal-to-lateral ratio are formed into a three-dimensional coffin material, and the elastic material is immersed and hardened to form the gasket. 12. Conductive gasket according to claim 1)
In the method of manufacturing, an elongated inner mandrel is surrounded by an elongated outer mold, and an elastic material, a hardening agent, and a carbon fiber mixture preferably oriented over the length of the mandrel are interposed between the mandrel and the mold group.
8-w is filled, the mixture is cured, the outer mold is removed, and a gasket is made by cutting the cured mixture in a direction perpendicular to the longitudinal direction of the mandrel @ scarlet. How to make a conductive gasket with all its features. 13) In the method according to claim 12, a mixture in which the fibers are properly distributed and has an excessive length tM is obtained by using an elastic material, a hardening agent? Manufacturing a conductive gasket characterized by mixing carbon fibers and carbon fibers [7]. 14) In the method for making a gasket according to claim 1, the cutting method is selected to create a gasket with fibers protruding from the surface of the gasket so as to provide a good texture during use. A method of making a conductive gasket characterized by: