JP2010071373A - Sealant and method of producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealant usable over a long period even in a high temperature environment by eliminating a defect of the sealant consisting of expanded graphite, superior in durability without causing corrosion in a contacting mating material, capable of satisfying mechanical strength, durability, conformability and flexibility in a well-balanced and compatible manner, further leading to high production efficiency, and easily compatible with large item small scale production. <P>SOLUTION: This sealant is formed by molding a woven composition provided by weaving a plurality of strap-shaped bodies consisting of a string-shaped body formed by bundling as one piece or twisting a belt-shaped piece consisting of a plurality of expanded graphite and a metal wire rod woven so as to coat the outer surface of the string-shaped body. Clay is filled in the eye of textile and the surface is coated with the clay in the woven composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sealing material and a manufacturing method thereof, and more particularly to a sealing material composed of a composite material of expanded graphite, metal and clay, and a manufacturing method thereof.

  Conventionally, asbestos products have been widely used as sealing materials such as gaskets and packings. However, since it has become clear that asbestos has a serious adverse effect on the human body, in recent years, products using alternative materials in place of asbestos have been used.

As a sealing material replacing asbestos products, for example, a sealing material made of expanded graphite is known.
However, expanded graphite is excellent in heat resistance, flexibility, compression recovery property, alkali resistance, water resistance, and the like, but has a drawback of low mechanical strength such as bending strength and tensile strength.
In addition, although expanded graphite is excellent in heat resistance, in the presence of oxygen, oxidative disappearance of expanded graphite is promoted in a temperature range exceeding 400 ° C. Therefore, it becomes difficult for a sealing material made of expanded graphite to maintain a stable sealing property over a long period of time in a high temperature environment exceeding 400 ° C.

On the other hand, a sealing material made of a composite material of expanded graphite and metal has been proposed in order to eliminate the disadvantage that expanded graphite has low mechanical strength.
For example, Patent Document 1 below discloses a sealing material made of a reinforcing material made of a compressed wire mesh and expanded graphite filling the mesh of the reinforcing material.
This sealing material is formed by winding an expanded graphite sheet on the outer periphery of a cylindrical body (A) obtained by spirally winding a laminated sheet obtained by laminating an expanded graphite sheet and a reinforcing material made of a sheet-like wire mesh. The outer surface layer forming member (B) housed in a sheet and formed into a sheet shape is wound (see FIG. 13) and then compression molded.

However, the sealing material disclosed in Patent Document 1 has many drawbacks.
First, in the sealing material of Patent Document 1, in order to prevent oxidative disappearance of expanded graphite, phosphorus pentoxide and phosphate are mixed with expanded graphite. There is a risk of corroding the material (pipe, etc.). Patent Document 1 also discloses a sealing material in which a lubrication slip layer made of a fluororesin (PTFE) is formed on the outer surface. However, PTFE generates fluorine gas when it exceeds about 370 ° C. Cannot be used in a high temperature environment exceeding 400 ° C.
Secondly, since the outer surface layer forming member (B) located on the outer surface of the sealing material has a cut (C), the sealing material may be damaged starting from the cut and causing leakage, which is a problem in terms of durability. There is.
Third, since the wire mesh is composed of a single type of metal wire, the characteristics of the sealing material are greatly affected by the type of metal wire used. For example, when a hard metal wire is used, mechanical strength and durability are improved, but conformability and flexibility are lowered. For this reason, it is difficult to adjust both the mechanical strength and durability, and the conflicting properties such as conformability and flexibility to achieve a good balance.
Fourth, since the manufacturing process is complicated and it is difficult to perform each process automatically and continuously, the production efficiency is low and the manufacturing cost is high.
Fifth, the size of the product is determined by the dimensions of the expanded graphite sheet. Therefore, if you try to change the product size, you must prepare an expanded graphite sheet of a different size each time, which corresponds to high-mix low-volume production. Is difficult.

JP 2001-99325 A

  The present invention has been made to solve the above-described problems, can solve the drawbacks of the sealing material made of expanded graphite, and can be used for a long time even in a high-temperature environment. It does not cause corrosion in the mating material, has excellent durability, and can balance mechanical strength, durability, conformability and flexibility in a well-balanced manner. It is an object of the present invention to provide a sealing material that can be easily applied to small-scale production and a method for manufacturing the same.

  The invention according to claim 1 is composed of a thread-like body formed by bundling or twisting a plurality of strip-shaped pieces made of expanded graphite, and a metal wire knitted so as to cover the outer surface of the thread-like body. A sealing material formed by forming a braided body obtained by knitting a plurality of string-like bodies, wherein the braided body is filled with clay and the surface thereof is covered with clay. Regarding materials.

In the invention according to claim 2, the metal wire is composed of a hard metal wire and a soft metal wire, the Brinell hardness of the hard metal wire is 90 to 240 (kg / mm ² ), and the soft metal wire Brinell hardness is 40-55 (kg / mm < ² >), It is related with the sealing material of Claim 1 characterized by the above-mentioned.

  The invention according to claim 3 relates to the sealing material according to claim 2, wherein the hard metal wire is made of nitridized stainless steel, and the soft metal wire is made of copper.

  The invention according to claim 4 is characterized in that pitches of the stitches of the metal wire knitted so as to cover the outer surface of the filament are 1.5 to 6 mm in the length direction and the width direction, respectively. It is related with the sealing material in any one of claim | item 1 thru | or 3.

  The invention according to claim 5 is the sealing material according to any one of claims 1 to 4, wherein the braided body is a cylindrical body obtained by bag-knitting a plurality of the string-like bodies. About.

  The invention according to claim 6 is characterized in that one end or both ends of the braided body are folded outward, and a gap portion between the folded portion and the unfolded portion is filled with clay. 5. The sealing material according to 5.

  The invention according to Claim 7 is a gasket according to any one of Claims 1 to 6, which is a gasket.

  The invention according to claim 8 relates to the sealing material according to claim 7, which is a spherical gasket.

  In the invention according to claim 9, the expanded graphite sheet is cut into thin strips to form strips made of expanded graphite, and a plurality of the strips are overlapped or covered on the outer surface of the thread-like body. A metal wire is knitted to form a string-like body, and a plurality of the string-like bodies are knitted into a bag to form a tubular braid, and clay particles are dispersed in the braid. A method for producing a sealing material, comprising impregnating a clay dispersion, drying a braided body impregnated with the clay dispersion, and molding the dried braided body with a mold to form a sealing material having a predetermined shape About.

In the invention according to claim 10, the metal wire comprises a hard metal wire and a soft metal wire, the Brinell hardness of the hard metal wire is 90 to 240 (kg / mm ² ), and the soft metal wire Brinell hardness is 40-55 (kg / mm < ² >), It is related with the manufacturing method of the sealing material of Claim 9 characterized by the above-mentioned.

  The invention according to claim 11 is characterized in that the hard metal wire is made of stainless steel, the soft metal wire is made of copper, and a sealing material having a predetermined shape obtained by the molding process using the mold is nitrided. It is related with the manufacturing method of the sealing material of Claim 10.

  The invention according to claim 12 is characterized in that the pitch of the stitches of the metal wire knitted so as to cover the outer surface of the filament is 1.5 to 6 mm in the length direction and the width direction, respectively. It relates to the manufacturing method of the sealing material in any one of claim | item 9 thru | or 11.

  The invention according to claim 13 is characterized in that, before the step of impregnating the braided body with the clay dispersion liquid, one end or both ends of the braided body are folded outward. The present invention relates to a method for manufacturing a material.

  The invention according to claim 14 is characterized in that a clay film obtained from the clay dispersion is interposed in a gap portion between the portion folded outward and the portion not folded back. It relates to the manufacturing method.

  The invention according to claim 15 relates to the method of manufacturing a seal material according to any one of claims 9 to 14, wherein the seal material is a gasket.

  The invention according to claim 16 relates to the method of manufacturing a sealing material according to claim 15, wherein the gasket is a spherical gasket.

According to the first aspect of the present invention, a thread-like body formed by superimposing or twisting strips made of a plurality of expanded graphite, and a metal wire knitted so as to cover the outer surface of the thread-like body, Because it is a sealing material formed by forming a braided body obtained by knitting a plurality of string-like bodies made of, the expanded graphite has excellent properties such as heat resistance, flexibility, compression recovery, alkali resistance, water resistance, etc. While maintaining the above, mechanical strength such as bending strength and tensile strength can be improved by the metal wire.
In addition, since the metal wire is knitted so as to cover the outer surface of the filamentous body made of expanded graphite, the expanded graphite and the metal wire are stronger and more uniform than when the expanded graphite sheet is laminated on the metal wire. Integrated. Therefore, it is possible to reliably exhibit the excellent characteristics of the expanded graphite and the metal wire in a balanced manner.
In addition, the braided body is such that the surface of the material constituting the braided body is covered with a clay film because the braid is filled with clay and the surface is covered with clay. Therefore, it has very high heat resistance, and can be used in a state where high sealing performance is maintained for a long time even in a high temperature environment exceeding 400 ° C. In addition, there is no possibility of corroding the mating material that the sealing material contacts.
In addition, because it is a sealing material formed by braiding a braided body obtained by knitting a plurality of string-like bodies, the sealing material does not have a cut line and does not cause breakage, so it has excellent durability Thus, high sealing performance can be exhibited over a long period of time.

According to the invention which concerns on Claim ² , a metal wire consists of a hard metal wire and a soft metal wire, Brinell hardness of the said hard metal wire is 90-240 (kg / mm < ² >), The said soft metal wire Since the Brinell hardness is 40 to 55 (kg / mm ² ), the excellent mechanical strength and durability of the hard metal wire and the excellent conformability and flexibility of the soft metal wire are made compatible. be able to. Further, by changing the ratio of the number of hard metal wires and soft metal wires, it is possible to easily adjust the balance between mechanical strength and durability, conformability and flexibility.

  According to the third aspect of the invention, the hard metal wire is made of nitridized stainless steel, and the soft metal wire is made of copper, so that excellent mechanical strength is exhibited by the nitridized stainless steel, and copper is more excellent. Familiarity is demonstrated.

  According to the invention which concerns on Claim 4, since the pitch of the stitch of the metal wire knitted so that the outer surface of a filament may be coat | covered is 1.5-6 mm in the length direction and the width direction, respectively, In addition to exhibiting excellent mechanical strength, the expanded graphite that has entered the mesh of the metal wire exhibits excellent conformability.

According to the invention which concerns on Claim 5, since the braided body is a cylindrical body obtained by bag-knitting a plurality of string-like bodies, the process of manufacturing the braided body can be automated. Therefore, production efficiency is increased and manufacturing costs can be kept low.
In addition, since the size of the braided body can be easily and freely changed at the time of manufacture, it is easy to cope with high-mix low-volume production.

  According to the invention of claim 6, one end or both ends of the braided body are folded outward, and the gap between the folded portion and the unfolded portion is filled with clay, whereby the braided body is Since the clay has a multilayer structure on the side surface, the heat resistance and sealability of the sealing material can be greatly improved.

  According to the invention which concerns on Claim 7, it becomes a gasket which has the outstanding characteristic mentioned above.

  According to the invention which concerns on Claim 8, it becomes a spherical gasket which has the outstanding characteristic mentioned above.

According to the invention which concerns on Claim 9, it becomes possible to automate the process of forming a braided body. Therefore, production efficiency is increased and manufacturing costs can be kept low.
Further, since the size of the braided body can be easily and freely changed, it is easy to cope with a large variety of small-quantity production.
Furthermore, the obtained sealing material has the characteristics such as the excellent heat resistance, flexibility, compression recovery, alkali resistance, water resistance and the like possessed by the expanded graphite and the excellent mechanical strength possessed by the metal wire. .
Further, by forming a string-like body by knitting a metal wire so as to cover the outer surface of the filamentous body made of expanded graphite, expanded graphite and the metal wire are compared with the case where an expanded graphite sheet is laminated on the metal wire. It is integrated firmly and without bias. Therefore, it is possible to reliably exhibit the excellent characteristics of the expanded graphite and the metal wire in a balanced manner.
Moreover, the surface of the material which comprises a braided body will be coat | covered with the clay film by impregnating a braided body in a liquid with a clay dispersion liquid. Therefore, it has very high heat resistance and can be used for a long time even in a high temperature environment exceeding 400 ° C. In addition, there is no possibility of corroding the mating material that the sealing material contacts.
In addition, since a braided body is formed by knitting a plurality of string-like bodies to form a sealing material, the sealing material does not have a cut line, and does not break from the cut line, thus exhibiting excellent durability. Can do.

According to the invention which concerns on Claim 10, a metal wire consists of a hard metal wire and a soft metal wire, Brinell hardness of the said hard metal wire is 90-240 (kg / mm < ² >), The said soft metal wire Since the Brinell hardness is 40 to 55 (kg / mm ² ), the excellent mechanical strength and durability of the hard metal wire and the excellent conformability and flexibility of the soft metal wire are made compatible. be able to. Further, by changing the ratio of the number of hard metal wires and soft metal wires, it is possible to easily adjust the balance between mechanical strength and durability, conformability and flexibility.

  According to the eleventh aspect of the present invention, the hard metal wire is made of stainless steel, the soft metal wire is made of copper, and the sealing material having a predetermined shape obtained by the molding process using the mold is nitrided, so that it is nitrided. Stainless steel exhibits excellent mechanical strength, and copper that is not nitrided exhibits excellent conformability.

  According to the invention of claim 12, since the pitch of the stitches of the metal wire knitted so as to cover the outer surface of the filament is 1.5 to 6 mm in the length direction and the width direction, respectively, the metal wire In addition to exhibiting excellent mechanical strength, the expanded graphite that has entered the mesh of the metal wire exhibits excellent conformability.

  According to the invention of claim 13, before the step of impregnating the braided body with the clay dispersion liquid, one end or both ends of the braided body are folded outward to reduce the height of the braided body before molding. It is possible to reduce the size of the mold by reducing the height thereof.

  According to the invention of claim 14, the clay has a multilayer structure on the side surface of the braid by interposing the clay film obtained from the clay dispersion in the gap portion between the portion folded back to the outside and the portion not folded back. Therefore, the heat resistance and sealability of the sealing material can be greatly improved.

  According to the invention which concerns on Claim 15, the gasket which has the outstanding characteristic mentioned above can be manufactured.

  According to the invention which concerns on Claim 16, the spherical gasket which has the outstanding characteristic mentioned above can be manufactured.

Hereinafter, preferred embodiments of a sealing material and a method for producing the same according to the present invention will be described with reference to the drawings as appropriate.
In the following description, a spherical gasket is used as an example of the sealing material according to the present invention. However, the sealing material according to the present invention includes other types of gaskets such as sheet gaskets, packings, joint sheets, and the like. Sealing materials other than these gaskets are also included.

First, the manufacturing method of the sealing material which concerns on this invention is demonstrated.
As a first step, as shown in FIG. 1, a long expanded graphite sheet (1) wound around a roll is cut into a strip shape to form a thin strip (2) made of expanded graphite.

  The expanded graphite sheet (1) is obtained by reacting graphite powder such as natural graphite, pyrolytic graphite, quiche graphite, etc. with concentrated sulfuric acid, concentrated nitric acid, etc. to form an intercalation compound, and then residually decomposing it by washing or the like to obtain a residual compound. The expanded graphite obtained by rapidly heating the expanded graphite can be obtained by a known production method such as a method of forming a flexible sheet by forming with a rolling roll.

The thickness of the expanded graphite sheet (1) is not particularly limited, but is preferably about 0.1 to 0.6 mm.
This is because if the thickness is less than 0.1 mm, sufficient strength cannot be obtained and the strip (2) may break during the subsequent knitting, and if the thickness exceeds 0.6 mm, the knitting is good. This is because it is not preferable in either case.

The density of the expanded graphite sheet (1) is not particularly limited, but a density of about 0.70 to 2.0 g / cm ³ is preferably used.
This is because if the density is less than 0.70 g / cm ³ , the thermal conductivity and the strength may be lowered, and if it exceeds 2.0 g / cm ³ , the flexibility may be lowered.

The width of the strip (2) obtained by cutting the expanded graphite sheet (1) is preferably 2.0 to 8.0 mm.
This is because if the width is less than 2.0 mm, sufficient strength cannot be obtained and the strip (2) may break during the subsequent knitting, and if the width exceeds 8.0 mm, the knitting is good. This is because it is not preferable in either case.

In the second step, as shown in FIG. 2, the thread-like body (20) composed of a plurality (two in the illustrated example) of the strip-like pieces (2) obtained in the first step is the center. The metal wire (3) is knitted so as to cover the outer surface of) to form the string-like body (4).
The thread-like body (20) may be a twisted yarn obtained by twisting a plurality of strips (2), or may simply be piled up without being twisted.
In the illustrated example, the thread-like body (20) is composed of two strip-shaped pieces (2), and the number of metal wires (3) covering the thread-like body (20) is one, but the strip-shaped piece (2 ) May be three or more, and the metal wire (3) may be two or more.
By changing the ratio of the number of strips (2) and metal wire (3), the balance between the properties exhibited by the strips (2) made of expanded graphite and the properties exhibited by the metal wires (3) The sealing material which has the characteristic according to a use application can be obtained.

In this invention, it is preferable to use two types of metal wires, a hard metal wire and a soft metal wire, as the metal wire (3). In this case, two types of metal wires may be overlapped or twisted to form one, and this may be used as a knitting yarn that covers the outer surface of the filamentous body (20).
As the hard metal wire, one having a Brinell hardness of 90 to 240 (kg / mm ² ) is used.
A metal material having such hardness has high mechanical strength such as tensile strength at high temperatures, and also has a high fatigue limit against repeated loads. Further, the metal having such hardness is unlikely to creep at a high temperature.
Accordingly, the hard metal wire can improve the mechanical strength of the sealing material and increase the creep resistance at high temperatures so that stress relaxation does not occur in the sealing material.

Examples of the hard metal wire include carbon steel such as stainless steel and Inconel, nickel, and a nickel alloy.
The diameter of the hard metal wire is preferably 0.05 to 0.35 mm. If the diameter is less than 0.05 mm, there is a risk of breaking when knitting, and if it exceeds 0.35 mm, knitting becomes difficult, which is not preferable in either case.

As the soft metal wire, one having a Brinell hardness of 40 to 55 (kg / mm ² ) is used.
Since the metal material having such hardness is lower in hardness than the counterpart material with which the seal material comes into contact, the counterpart material is not damaged when the seal material is displaced relative to the counterpart material. Further, the metal material having such hardness is excellent in flexibility and can be easily plastically processed.
Therefore, the larger the proportion of the soft metal wire, the easier the knitting process in the second step. Moreover, when the thing obtained from the string-like body (4) obtained by knitting is pressure-molded and used as a sealing material, the sealing material with a dense surface and interior can be obtained.
Further, the metal material having such hardness has good conformability to the counterpart material. Therefore, the sealing property of the sealing material can be improved as the proportion of the soft metal wire increases.
Furthermore, the metal material having such hardness is not easily altered at a temperature of about 400 to 850 ° C. Therefore, the sealing performance of the sealing material can be stabilized at a high temperature.

Examples of the soft metal wire include copper alloys such as copper and monel metal, aluminum, and aluminum alloys.
The diameter of the soft metal wire is preferably 0.05 to 0.35 mm. If the diameter is less than 0.05 mm, there is a risk of breaking when knitting, and if it exceeds 0.35 mm, knitting becomes difficult, which is not preferable in either case.

When using two types of metal wires, a hard metal wire and a soft metal wire, as the metal wire (3), the ratio of the number of both is preferably 1: 1 to 0.3. When this is expressed as a ratio value (number of hard metal wires / number of soft metal wires), it is 1 to about 3.3.
If the ratio value is less than 1, the mechanical strength of the string-like body (4) becomes low. Conversely, if it exceeds 3.3, the knitting process becomes difficult, and the conformability of the string-like body decreases, resulting in a seal. In any case, the sealing performance of the material may be lowered, which is not preferable.

The pitch of the stitches of the metal wire (3) knitted so as to cover the outer surface of the filamentous body (20) is preferably 1.5 to 6 mm in the length direction and the width direction, respectively. FIG. 3 is an explanatory diagram of the stitch pitch length direction (L) and width direction (W).
If the pitch of the stitch of the metal wire (3) is less than 1.5 mm, the expanded graphite does not easily enter the mesh, so that the adaptability and sealability of the seal material cannot be obtained sufficiently. In either case, the strength of the material decreases, which is not preferable.

The knitting method (knitting structure) of the metal wire (3) may be warp knitting or weft knitting, but weft knitting is preferred from the viewpoint of strength.
In the case of weft knitting, the specific form is not particularly limited, and flat knitting, rubber knitting, pearl knitting, tuck knitting, floating knitting, single knitting, double knitting, double knitting, lace knitting, splicing knitting The form of can be adopted.

Since the string-like body (4) formed in the second step is formed from the filamentous body (20) made of expanded graphite and the metal wire (3), it is more familiar than that formed only from the metal wire. The characteristics are greatly improved. In addition, when the braided body obtained from the string-like body (4) in the subsequent process (sixth process) is subjected to pressure molding to form a sealing material, the expanded graphite enters the gaps in the metal wire (3). It can be a sealing material whose inside is very densely packed.
Thus, by using the strip-like piece (2) made of expanded graphite for the string-like body (4), the sealing performance of the sealing material is greatly improved compared to the case where only the metal wire is used. Is possible.

In the second step, the ratio of the number of the strips (2) made of expanded graphite and the metal wire (3) is preferably 1: 0.5 to 5.0. When this is expressed by a ratio value (number of strips / number of metal wires), it is 2 to 0.2.
If the ratio value exceeds 2, the mechanical strength of the sealing material may decrease and the friction may increase. Conversely, if it is less than 0.2, the conformability decreases and the sealing property of the sealing material decreases. In either case, it is not preferable.

The string-like body (4) obtained in the second step is preferably subjected to a step of pressurizing from the surroundings and making it thin by passing through a die before being subjected to the third step. In this step, the string-like body (4) may be twisted.
By passing through such a step before the third step, the strip (2) made of expanded graphite constituting the string-like body (4) and the metal wire (3) can be firmly integrated.

In the third step, as shown in FIG. 4, a plurality of the string-like bodies (4) obtained in the second step are knitted into bags, and then cut into a predetermined length to form a cylinder as shown in FIG. A shaped braid (5) is formed. For bag knitting, a known bag knitting machine can be used.
The diameter of the braided body (5) may be set as appropriate according to the size of the sealing material as the final product, and can be easily and freely changed by the setting of the bag knitting machine. it can.
The height of the braided body (5) (vertical length in FIG. 5) may be set as appropriate according to the dimensions of the sealing material that is the final product, but may be, for example, 15 to 200 mm. In addition, since the sealing material is obtained by press-molding the braided body (5) in the height direction, the height of the braided body (5) is higher than the height of the sealing material that is the final product.

  The number of string-like bodies (4) used for bag knitting is not particularly limited, but is preferably 6 to 50. This is because if the number is less than 6, the braided body (5) becomes rough and the strength is lowered, and if it exceeds 50, the braiding becomes difficult and the cost is increased, which is not preferable in any case.

Since both the second step and the third step described above can be processed continuously and can be automated, the production efficiency can be increased and the manufacturing cost can be kept low.
In addition, since the size of the braided body can be easily and freely changed at the time of manufacture, it is easy to cope with high-mix low-volume production.

In the fourth step, the braided body (5) obtained in the third step is impregnated with a clay dispersion liquid (6) in which clay particles are dispersed in the liquid.
Examples of the liquid in which the clay particles are dispersed include water, alcohol, ether, ethyl acetate, toluene and the like.
The impregnation method of the clay dispersion may be a method of immersing the braid (5) in the clay dispersion (6) as shown in FIG. 6, or applying the clay dispersion (6) to the braid (5). The method of spraying may be used and is not particularly limited.

As the clay, one or more of natural clay, synthetic clay and modified clay can be used.
More specifically, at least one of mica, vermiculite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, isralite, kanemite, illite, sericite, and nontronite is preferably used.

The clay used for the modified clay is natural or synthetic, preferably, for example, mica, vermiculite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, ilarite, kanemite, illite, sericite. One or more of these, more preferably, any of these natural or synthetic products, or a mixture thereof.
Examples of the organic cation used in the modified clay include those containing a quaternary ammonium cation or a quaternary phosphonium cation. In that case, the structure which makes the organic cation composition in modified clay less than 30 weight% is employable.
Moreover, what made the silylating agent react with the modified clay can also be used. In this case, a configuration in which the silylating agent composition is less than 30% by weight based on the total weight of clay and silylating agent can be employed.

Examples of organic substances contained in the modified clay include quaternary ammonium cations, quaternary phosphonium cations, imidazolium cations, and pyridium cations. Although it does not specifically limit as a quaternary ammonium cation, A dimethyl octadecyl type, a dimethyl stearyl benzyl type, and a trimethyl stearyl type are illustrated. Moreover, a quaternary phosphonium cation is illustrated as a similar organic substance. These organic substances are introduced into the clay by ion exchange of the raw clay.
This ion exchange is performed, for example, by dispersing raw clay in water in which excess organic matter is dissolved, stirring for a certain time, solid-liquid separation by centrifugation or filtration, and repeated washing with water. These ion exchange processes may be performed only once or may be repeated a plurality of times. By repeating a plurality of times, the ratio of exchangeable ions such as sodium and calcium contained in the clay by the organic matter increases. The polarity of the modified clay can vary depending on the organic substance used and the exchange ratio, and different polar modified clays have different suitable additives and suitable solvents. At this time, a quaternary ammonium cation chloride is generally used as a reagent used for introducing a quaternary ammonium cation. Chlorine mixed with the introduction of the quaternary ammonium cation is diluted by water washing, but it is difficult to reduce the concentration to 150 ppm or less even if water washing is repeated. However, some electronics applications are extremely reluctant to mix chlorine, and therefore the chlorine concentration may have to be suppressed to 150 ppm or less. In such a case, quaternary ammonium chloride must not be used, and other chlorine-free reagents such as quaternary ammonium bromide, quaternary ammonium cation hydroxide must be used.

The silylating agent contained in the modified clay is not particularly limited, but methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, dodecyl Examples thereof include trimethoxysilane and octadecyltrimethoxysilane.
Also, the method for introducing the silylating agent into the clay is not particularly limited. For example, the raw clay and 2% by weight of the silylating agent are mixed with the raw clay, and these are mixed with a ball mill for one hour. A method of milling can be exemplified.

  The modified clay used in the present invention can be prepared in various polarities depending on the treatment method, and the solvent suitable for preparing the clay dispersion varies depending on the polarity. Examples of the solvent for preparing the clay dispersion include alcohol, ether, ethyl acetate, toluene and the like.

The clay dispersion (6) can be obtained by uniformly dispersing clay particles made of natural or synthetic smectite, or a mixture thereof in a liquid such as water or an organic solvent described above.
The ratio of the solid content contained in the clay is preferably 3 to 15% by weight. The concentration of the clay dispersion is preferably 0.5 to 10% by weight, more preferably 1 to 3% by weight. Furthermore, if necessary, one or more additives can be added to the clay dispersion to be uniformly dispersed or dissolved in the liquid.

  Additives include celluloid, phenolic resin, alkyd resin, urea resin, cellulose acetate, vinyl acetate resin, acrylic resin, styrene resin, vinyl chloride resin, melamine resin, polyethylene, polyurethane resin, vinylidene chloride resin, polyamide resin, unsaturated Polyester, silicon resin, acrylonitrile-styrene resin, fluororesin, epoxy resin, diallyl phthalate resin, acrylonitrile-budadiene-styrene resin, polyethylene terephthalate, polypropylene, polycarbonate, polyacetal, polyimide, polysulfone, polyphenylene ether, polybutylene terephthalate, polyether One or more of sulfone, liquid crystal polymer, polyphenylene sulfide, and polyetherimide can be used.

Further, the clay dispersion liquid (6) includes phosphorus such as red phosphorus and phosphorus pentoxide, primary lithium phosphate, secondary lithium phosphate, primary calcium phosphate, secondary calcium phosphate, primary aluminum phosphate and secondary aluminum phosphate. It is also possible to add one or more of the following phosphates.
By adding these phosphorus and / or phosphate to the clay dispersion, the effect of preventing oxidative disappearance of the expanded graphite under high temperature conditions is improved, and the sealing material containing phosphorus due to the presence of clay is improved. It is also possible to prevent corrosion of the mating material (piping, etc.).

In the fifth step, the braided body impregnated with the clay dispersion obtained in the fourth step is dried.
As shown in FIG. 7, the braided body after drying has the surface of the material (wire material) constituting the braided body covered with a clay film (7). In addition, the mesh is filled with clay.

In the sixth step, the braided body after drying is accommodated in the mold (8) as shown in FIG. 8 and press-molded in the height direction (arrow direction) to obtain a predetermined shape as shown in FIG. Let it be a sealing material (9). FIG. 9A is an external view, and FIG. 9B is a cross-sectional view.
The mold (8) has a known structure used for molding a sealing material such as a gasket and has an internal shape that matches the shape of the sealing material to be the final product.

In the present invention, after the pressure molding in the sixth step, the obtained molded body can be nitrided.
In this case, it is preferable to use two types of metal wires, stainless steel (hard metal wire) and copper (soft metal wire), as the metal wire (3). Moreover, it is preferable that the temperature of a nitriding process shall be 550-650 degreeC.
When nitriding a sealing material containing these two types of metal wires, the mechanical strength of the sealing material is greatly improved by nitriding stainless steel, while copper is not softened and maintains a soft state. Therefore, the conformability of the sealing material is good.
Further, since the nitriding treatment is performed in the absence of oxygen, the expanded graphite does not disappear due to heating in the nitriding treatment step.
The nitriding method is not particularly limited, and a known method such as a gas nitriding method, a salt bath nitriding method, a tuftride method, a gas soft nitriding method, a plasma nitriding method, or the like can be employed.
Among these, the plasma nitriding method using a mixed gas of nitrogen gas and hydrogen gas is suitable for the nitriding treatment of stainless steel.

  The sealing material (9) obtained as a final product is a sealing material according to the present invention, and a spherical gasket is shown in FIG. However, as described above, the sealing material according to the present invention is not limited to the spherical gasket.

The sealing material according to the present invention obtained by the method described above has excellent heat resistance, flexibility, compression recovery property, alkali resistance, water resistance of expanded graphite, and excellent mechanical strength of metal wire. It will be a thing.
Further, by forming a string-like body by knitting a metal wire so as to cover the outer surface of the filamentous body made of expanded graphite, expanded graphite and the metal wire are compared with the case where an expanded graphite sheet is laminated on the metal wire. It is integrated firmly and without bias. Therefore, it is possible to reliably exhibit the excellent characteristics of the expanded graphite and the metal wire in a balanced manner.
Further, by impregnating the braided body with the clay dispersion liquid, the braided body is one in which the knitting is filled with clay and the surface is covered with clay. Therefore, it has very high heat resistance (about 800 to 1000 ° C.) and can be used for a long time even in a high temperature environment exceeding 400 ° C. In addition, there is no possibility of corroding the mating material with which the sealing material comes into contact.
In addition, since a braided body is formed by knitting a plurality of string-like bodies to form a sealing material, the sealing material does not have a cut line, and does not break from the cut line, thus exhibiting excellent durability. Can do.

  Furthermore, when a hard metal wire and a soft metal wire are used as the metal wire, it has both excellent mechanical strength and durability that the hard metal wire has, and excellent adaptability and flexibility that the soft metal wire has. it can. Further, by changing the ratio of the number of hard metal wires and soft metal wires, it is possible to easily adjust the balance between mechanical strength and durability, conformability and flexibility.

In the production method according to the present invention, a step of folding back one end or both ends of the braided body (5) obtained in the third step between the third step and the fourth step (hereinafter referred to as a folding step). Can go through.
FIG. 10 is a diagram showing a state in which one end or both ends of the braided body (5) are folded outward by the folding step, (a) is a diagram in which the upper end is folded, and (b) is a diagram in which the lower end is folded. (C) is a diagram in which both ends (upper and lower ends) are folded.
In the manufacturing method according to the present invention, it is possible to adjust the height of the braided body before molding by folding back one end or the other end of the tubular braided body in this way. That is, the height of the braided body can be adjusted by changing the length (L) of the folded portion (10).
Thus, by passing through the folding step, the height of the braided body can be lowered before the forming step of the subsequent step (sixth step).
Thereby, it is possible to reduce the size of the mold (8) used in the sixth step by reducing the height.

Moreover, in the manufacturing method which concerns on this invention, it passes through the process (henceforth a clay filling process) which fills the clearance gap part between a folding | returning part (10) and the part which is not folded after the folding process mentioned above. Can do.
In the clay filling step, a clay film (11) obtained from the above-described clay dispersion is interposed in the gap portion (see FIG. 11).
The number of clay films (11) to be interposed is not particularly limited, and may be one or more.

The clay film (11) can be produced by the following method.
First, a clay dispersion is prepared by the method described above.
Next, the clay dispersion is allowed to stand horizontally to slowly deposit the clay particles, and the clay thin film is formed by separating the liquid as the dispersion medium and the clay particles by solid-liquid separation means.
Finally, the clay film (11) is obtained by drying the clay thin film under a temperature condition of 110 to 300 ° C.

As the solid-liquid separation means in the above production method, any one of centrifugation, filtration, vacuum drying, freeze vacuum drying, heat evaporation, or a combination of these means is employed.
Among these methods, for example, when using the heating evaporation method, the clay dispersion liquid previously degassed by evacuation is poured into a flat tray, and in a state of maintaining the level, 30 to 70 ° C in a forced air oven, Preferably, the clay film is obtained by drying under a temperature condition of 40 to 50 ° C. for about 3 hours to half a day, preferably 3 to 5 hours.

The clay film thus produced has strength that can be used as a self-supporting film, and the laminate of clay particles is highly oriented.
The highly oriented lamination of clay particles means that the unit structure layers (thickness: about 1 nm) of clay particles are stacked with the same layer surface direction, and have a high periodicity in the direction perpendicular to the layer surface. is doing. In order to obtain such clay particle orientation, a thin and uniform clay dispersion is allowed to stand horizontally, and the clay particles are slowly deposited, and for example, the liquid as a dispersion medium is slowly evaporated to form a film. It is necessary to form in a shape.

The clay film thus obtained has a thickness of 3 to 100 μm, preferably 3 to 30 μm, and has a gas barrier performance of 30 μm and an oxygen permeability of less than 0.1 cc / m ² · 24 hr · atm, hydrogen The transmittance is less than 0.1 cc / m ² · 24 hr · atm. The gas permeability coefficient at room temperature of helium, hydrogen, oxygen, nitrogen, and air is less than 3.2 × 10 ⁻¹¹ cm ² s ⁻¹ cmHg ⁻¹ , and the gas barrier property is not lowered even after heat treatment at 1000 ° C. for 24 hours. I can't see it.
Further, the water shielding property has a water shielding coefficient of 2 × 10 ⁻¹¹ cm / s or less, and the light transmission property is a transmittance of visible light (500 nm) of 75% or more, and the area is as large as 100 × 40 cm or more. It is possible to increase the area and has high heat resistance.

  This clay film has a highly oriented laminate of clay particles and no pinholes. Moreover, it is excellent in flexibility and does not change its structure even at a high temperature of 250 ° C. to 600 ° C. Furthermore, it can be used as a self-supporting film, is a dense material free of pinholes, and has excellent gas / liquid barrier properties.

As described above, such a clay film is interposed in a gap portion of the braided body (5) formed by the folding process in the clay filling process. Thereafter, the braided body (5) is impregnated with the clay dispersion (6) and dried.
In the braided body obtained through the clay filling step, the clay has a multilayer structure on the side surface of the braided body. That is, the clay layer is formed in three layers of the inner surface side, the outer surface side, and the gap portion of the braided body (5). Moreover, the compatibility and compatibility of expanded graphite and clay film are very good.
Therefore, it becomes possible to greatly improve the heat resistance and sealing performance of the sealing material obtained by molding this braided body.

Hereinafter, the effect of the present invention will be made clearer by showing examples of the sealing material according to the present invention. However, the present invention is not limited to the following examples.
<Preparation of Example Sample>
Through the first to sixth steps described above, a spherical gasket (outer diameter φ70 mm, inner diameter φ53.5 mm, height 16 mm) as shown in FIG. 9 was manufactured, and this was used as the spherical gasket of the example. The expanded graphite sheet was 0.38 mm thick, and the width of the strip was 3 mm. As the metal wire, SUS304 (non-nitride) having a diameter of 0.15 mm was used. The pitch of the metal wire mesh (see FIG. 3) was 4.5 mm in the length direction (L) and 3 mm in the width direction (W), and 24 string-like bodies were used in the bag knitting in the third step.
On the other hand, spherical gaskets having the same shape as the examples were manufactured using only expanded graphite, and these were used as the spherical gaskets of the comparative examples.

<Heat-resistant seal test>
As shown in FIG. 12, the spherical gasket (9) of the example is interposed between flanges (made of stainless steel) formed in the vicinity of the ends of two pipes (made of stainless steel, outer diameter φ53 mm). SUS wool (12) packed in the pipe so that the temperature of the flange spherical surface is 700 ° C. is heated for 24 hours with a gas burner (13) by tightening with a load via a spring with a bolt of 588.4 N (60 kgf). After that, the movable portion of the flange spherical surface portion was slid repeatedly 10 times up and down 10 mm each, and then the amount of air leakage was measured when internal pressure (air pressure) 19.6 kPa (0.2 kgf / cm ² ) was applied.
As a result, the air leakage amount was 13.9 ml / min, which was significantly lower than the application standard value of 500 ml / 30 sec for automobile exhaust pipe parts.

<Heat resistance test>
The spherical gaskets of the examples and comparative examples were heated in an electric furnace at 600 ° C. for 24 hours, and the weight before and after heating was measured to calculate the weight reduction rate. The results are shown in Table 1.

  As shown in Table 1, the weight reduction rate of the spherical gasket of the example was 11%, whereas the weight reduction rate of the spherical gasket of the comparative example was 24%. From this result, it was confirmed that the spherical gasket according to the present invention has higher heat resistance than the conventional one.

  INDUSTRIAL APPLICABILITY The present invention can be used as a sealing material for gaskets, packings, joint sheets, and the like used for joints of piping in power plants and chemical plants.

It is explanatory drawing of the 1st process of the manufacturing method of the sealing material which concerns on this invention. It is explanatory drawing of the 2nd process of the manufacturing method of the sealing material which concerns on this invention. It is explanatory drawing of the length direction (L) and the width direction (W) of the pitch of a stitch. It is explanatory drawing of the 3rd process of the manufacturing method of the sealing material which concerns on this invention. It is a figure which shows the braided body obtained by a 3rd process. It is explanatory drawing of the 4th process of the manufacturing method of the sealing material which concerns on this invention. It is a figure which shows the braided body after a 5th process. It is explanatory drawing of the 6th process of the manufacturing method of the sealing material which concerns on this invention. It is a figure which shows an example of the sealing material which concerns on this invention, (a) is an external view, (b) is sectional drawing. It is a figure which shows the state by which the one end or both ends of the braided body were turned outward by the folding | turning process, (a) is a figure of the state by which the upper end was folded, (b) is a figure of the state by which the lower end was folded, c) is a diagram showing a state in which both ends (upper and lower ends) are folded. It is sectional drawing which shows the braided body which passed through the clay filling process. It is a figure explaining the heat-resistant sealing property test method of the spherical gasket which concerns on this invention. It is sectional drawing which shows the state before the pressure molding of the conventional sealing material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Expanded graphite sheet 2 Strip | belt-shaped piece 3 which consists of an expanded graphite sheet 3 Metal wire material 4 String-like body 5 Braided body 6 Clay dispersion liquid 7 Clay film 8 Mold 9 Seal material (spherical gasket)
10 Folded part 11 Clay film 20 Filamentous body

Claims (16)

Knitting a plurality of string-like bodies composed of a filamentous body obtained by superimposing or twisting a plurality of strips made of expanded graphite, and a metal wire knitted so as to cover the outer surface of the filamentous body. A sealing material formed by molding the resulting braided body,
The braided body is a sealing material characterized in that the knitting is filled with clay and the surface is covered with clay. The metal wire consists of a hard metal wire and a soft metal wire,
The Brinell hardness of the hard metal wire is 90 to 240 (kg / mm ² ), and the Brinell hardness of the soft metal wire is 40 to 55 (kg / mm ² ). Sealing material.   The sealing material according to claim 2, wherein the hard metal wire is made of nitridized stainless steel, and the soft metal wire is made of copper.   The pitch of the stitches of the metal wire knitted so as to cover the outer surface of the filamentous body is 1.5 to 6 mm in the length direction and the width direction, respectively. Sealing material.   The sealing material according to any one of claims 1 to 4, wherein the braided body is a cylindrical body obtained by bag-knitting a plurality of the string-like bodies.   6. The sealing material according to claim 5, wherein one end or both ends of the braided body are folded outward, and a gap portion between the folded portion and the unfolded portion is filled with clay.   The sealing material according to claim 1, wherein the sealing material is a gasket.   The sealing material according to claim 7, which is a spherical gasket. Cutting the expanded graphite sheet into thin strips to form strips of expanded graphite,
A string-like body is formed by knitting a metal wire so as to cover the outer surface of the filamentous body obtained by superimposing or twisting a plurality of the strip-like pieces into one,
Forming a tubular braid by bag-knitting a plurality of the string-like bodies;
Impregnating the braided body with a clay dispersion in which clay particles are dispersed in the liquid;
Drying the braided body impregnated with the clay dispersion;
A method for producing a sealing material, wherein the braided body after drying is molded with a mold to form a sealing material having a predetermined shape. The metal wire consists of a hard metal wire and a soft metal wire,
The Brinell hardness of the hard metal wire is 90 to 240 (kg / mm ² ), and the Brinell hardness of the soft metal wire is 40 to 55 (kg / mm ² ). Manufacturing method of the sealing material. The hard metal wire is made of stainless steel, the soft metal wire is made of copper,
The method for producing a sealing material according to claim 10, wherein the sealing material having a predetermined shape obtained by the molding process using the mold is subjected to nitriding treatment.   The pitch of the stitches of the metal wire knitted so as to cover the outer surface of the filamentous body is 1.5 to 6 mm in the length direction and the width direction, respectively. Manufacturing method of the sealing material. Before the step of impregnating the braided body with a clay dispersion,
The method for manufacturing a sealing material according to claim 9, wherein one end or both ends of the braided body are folded outward.   The method for producing a sealing material according to claim 13, wherein a clay film obtained from the clay dispersion is interposed in a gap portion between the portion folded back to the outside and the portion not folded back.   The method for manufacturing a sealing material according to claim 9, wherein the sealing material is a gasket.   The method for manufacturing a sealing material according to claim 15, wherein the gasket is a spherical gasket.

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