Method for producing a layered clay mineral, method for producing a sheet containing the layered clay mineral, and method for producing a sealing material

Abstract

To provide a method for producing a layered clay mineral in which the degree of freedom of a manufacturing method is improved in manufacturing a sheet, a seal material or the like.SOLUTION: A method for producing a layered clay mineral includes a slurry-forming step in which the swellable layered clay mineral is dispersed in a solvent to form a slurry, and a first ion-exchange step in which at least a part of a first cation in the interlayer of the swellable layered clay mineral is exchanged with K+ ion which is a second cation. The first ion exchange step is performed using a cation exchange resin.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The disclosure in the present application relates to a method for manufacturing a layered clay mineral, a method for manufacturing a sheet containing the layered clay mineral, and a method for manufacturing a sealing material.

Background Art

[0002] Sealing materials such as gaskets and packings are used for pipe flanges and the like in various industries. As gaskets, sheet gaskets, spiral gaskets, serrated gaskets, and the like are known.

[0003] A spiral gasket is formed by winding a hoop material and a filler material in a stacked state. A serrated gasket generally has a large number of concentric grooves with different diameters dug on both sides of a metal body in the radial direction at substantially equal pitches, and the cross section has a serrated (saw) tooth shape.

[0004] For example, Patent Document 1 describes a gasket using a delaminated clay mineral with high sealing performance. Further, Patent Document 2 describes that a sealing material with excellent water resistance can be obtained by using a layered clay mineral in which Na + ions are exchanged with K + ions or the like. Furthermore, Patent Document 3 describes that by ion-exchanging Na + and Li + between the layers of synthetic fluorine mica with K + , Ba 2+ , Pb 2+ or the like, a sheet with high heat resistance and high mechanical strength can be obtained without using organic substances such as adhesives and binders.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, Patent Documents 2 and 3 describe that the properties of the obtained sheet can be improved by performing ion exchange between the layers of the layered clay mineral. By the way, Patent Document 2 describes a method of producing a slurry in which cations between layers are replaced with cations in an aqueous solution by putting a swellable layered clay mineral into an aqueous solution containing cations and stirring, forming a mica exfoliation by freeze-drying the formed slurry, and producing a sheet by putting the formed mica exfoliation into a mold and compressing it. Further, Patent Document 3 describes a method of producing a sheet by spreading a sol in which synthetic swellable fluorophlogopite is dispersed in water on a stainless steel plate, drying, and dehydrating after washing a slurry of ion-exchanged synthetic swellable fluorophlogopite by a filtration method. However, Patent Documents 2 and 3 do not describe directly producing a sheet from a cation-exchanged slurry. In addition to the production methods described in Patent Documents 2 and 3, for example, it is preferable that the degree of freedom of the sheet production method is higher, such as directly producing a sheet from a cation-exchanged slurry, and it is desired to provide a slurry therefor.

[0007] The disclosure in the present application is made to solve the above problems. As a result of intensive research by the present inventors, (1) when producing a slurry using an aqueous solution containing K ions as a cation and simply replacing it with a continuous production method such as a doctor blade method, K ions remain in the sealing material, and the remaining K ions have an adverse effect on heat resistance; (2) when using a cation exchange resin to exchange at least a part of the cations between the layers of the swellable layered clay mineral with K ions, the amount of K ions remaining in the slurry decreases; (3) as a result, even if the slurry is dried as it is to produce a sealing material, the K remaining in the sealing material + ions are used to produce a slurry and simply replaced with a continuous production method such as a doctor blade method, K + ions remain in the sealing material, and the remaining K + ions have an adverse effect on heat resistance; (2) when using a cation exchange resin to exchange at least a part of the cations between the layers of the swellable layered clay mineral with K + ions, the amount of K + ions remaining in the slurry decreases; (3) as a result, even if the slurry is dried as it is to produce a sealing material, the K remaining in the sealing material+ Since the amount of ions decreases, it has been newly found that, in addition to the conventional production method, a sealing material can be continuously produced from a slurry by a continuous production method.

[0008] That is, the object of the disclosure in the present application is to provide a method for producing a layered clay mineral, a method for producing a sheet containing a layered clay mineral, and a method for producing a sealing material. [Means for Solving the Problems]

[0009] The disclosure in the present application relates to the following methods for producing a layered clay mineral, a method for producing a sheet containing a layered clay mineral, and a method for producing a sealing material.

[0010] (1) A method for producing a layered clay mineral, the method for producing the layered clay mineral comprising: a slurry formation step of dispersing a swellable layered clay mineral in a solvent to form a slurry; a first ion exchange step of exchanging at least a part of the first cation between the layers of the swellable layered clay mineral with a K + ion which is a second cation; and the first ion exchange step is carried out using a cation exchange resin A method for producing a layered clay mineral. (2) The method for producing a layered clay mineral according to (1) above, wherein the swellable layered clay mineral is a synthetic clay mineral. The method for producing a layered clay mineral according to (1) above. (3) The method for producing a layered clay mineral according to (2) above, wherein the synthetic clay mineral is selected from the group consisting of smectite, vermiculite, modified vermiculite, and synthetic fluoromica. The method for producing a layered clay mineral according to (2) above. (4) The method for producing a layered clay mineral according to (3) above, wherein the synthetic clay mineral is synthetic fluoromica. The method for producing a layered clay mineral according to (3) above. (5) The method for producing a layered clay mineral according to any one of (1) to (4) above, wherein the cation exchange resin is a strongly acidic cation exchange resin. The method for producing a layered clay mineral according to any one of (1) to (4) above. (6) After the first ion exchange step, a second ion exchange step is further included. In the second ion exchange step, using an anion exchange resin, F - ions contained in the slurry after the first ion exchange step are adsorbed onto the anion exchange resin. The method for producing a layered clay mineral according to (4) above. (7) After the first ion exchange step, a cation exchange resin removal step of removing the cation exchange resin from the slurry is further included. The method for producing a layered clay mineral according to any one of (1) to (6) above. (8) After the second ion exchange step, an anion exchange resin removal step of removing the anion exchange resin from the slurry is further included. The method for producing a layered clay mineral according to (6) above. (9) A method for producing a sheet containing a layered clay mineral, the method for producing the sheet comprising: a drying step of drying a slurry containing a layered clay mineral produced by the production method according to any one of (1) to (8) above. The method for producing a sheet. (10) The drying step is performed by drying while continuously stretching the slurry. The method for producing a sheet according to (9) above. (11) A method for producing a sealing material, the method for producing the sealing material comprising: a step of incorporating a sheet produced by the method for producing a sheet according to (9) or (10) above as a part of a gasket. The method for producing a sealing material. [Advantages of the Invention]

[0011] The production method disclosed in the present application can reduce the amount of K + ions contained in the slurry after at least a part of the first cations in the interlayer of the swellable layered clay mineral is exchanged with K + ions which are the second cations. Therefore, when producing a sheet, a sealing material, etc. using a slurry containing a layered clay mineral exchanged with K + ions, the degree of freedom of the production method is improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0013] Hereinafter, the method for producing a layered clay mineral, the method for producing a sheet containing the layered clay mineral, and the method for producing a sealing material will be described in detail.

[0014] (First Embodiment of the Method for Producing a Layered Clay Mineral) The first embodiment of the method for producing a layered clay mineral is a slurry forming step of dispersing a swelling layered clay mineral in a solvent to form a slurry, and a first ion exchange step of exchanging at least a part of the first cations existing between the layers of the swelling layered clay mineral with K + ions which are second cations, and includes wherein the first ion exchange step is carried out using a cation exchange resin.

[0015] The layered clay mineral disclosed in this application is obtained by replacing at least a part of the first cations (ions that impart swelling properties to the clay mineral) present between the layers of the swelling layered clay mineral with K + ions (minerals that impart non-swelling properties to the clay mineral), which are the second cations. Examples of the first cations that impart swelling properties to the layered clay mineral include, but are not limited to, Na + ions, Ca 2+ ions, Mg 2+ ions, Li + ions, and the like.

[0016] The swelling layered clay mineral is not particularly limited as long as it contains the above-mentioned first cations that impart swelling properties between the layers. The swelling layered clay mineral may be either a natural clay mineral or a synthetic clay mineral. Examples include mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite, nontronite, and the like. From the viewpoints of purity and quality stability rather than from the technical viewpoints disclosed in this application, synthetic clay minerals are preferred. Examples of synthetic clay minerals include, but are not limited to, smectite (the first cation is Na + ions, Ca 2+ ions, Mg 2+ ions), vermiculite (the first cation is Mg 2+ ions), modified vermiculite (the first cation is Li + ions), and synthetic fluoromica (the first cation is Na + ions), and the like. Among them, from the viewpoints of high heat resistance and moldability, synthetic fluoromica is preferred.

[0017] Synthetic fluoromica, which is an example of the swelling layered clay mineral, can be represented by the following formula (1). αMF·βLF·γ(aMgF2·bMgO)·δSiO2 Formula (1) (In the formula, M is an interlayer ion and represents one or more selected from K + , Ba 2+ and Pb 2+ , L is an interlayer ion, and is Na + or Li+ wherein α and β are 0<α≦2, 0≦β<2, and α+β is 0.1 to 2, γ is 2 to 3.5, δ is 3 to 4, a and b are each 0 to 1, and a+b=1. In an embodiment of the method for producing a layered clay mineral, the interlayer ion L (corresponding to the first cation) of the synthetic fluorine mica represented by the above formula (1) is a second cation K + is exchanged with ions.

[0018] The solvent for dispersing the swellable layered clay mineral to form a slurry is not particularly limited as long as it can be dried and does not adversely affect the heat resistance, etc., of the sheet after drying. Examples include protic solvents such as water and alcohol.

[0019] Cation exchange resins convert the primary cations contained between the layers of the swelling layered clay mineral into secondary cations, such as K. + There are no particular limitations as long as the resin can be exchanged for ions. For example, a strong acid cation exchange resin having a sulfo group, a weak acid cation exchange resin having a carboxyl group, etc. are listed. + By adsorbing ions, a cation exchange resin (sometimes referred to as "K-type ion exchange resin") used in the first embodiment can be provided. Strongly acidic K-type ion exchange resins are capable of ion exchange independent of the pH of the slurry. On the other hand, weakly acidic K-type ion exchange resins can be used in a narrower pH range than strongly acidic K-type ion exchange resins. It is only necessary to appropriately determine whether a strongly acidic or weakly acidic K-type ion exchange resin is to be used, taking into consideration the pH of the slurry. From the viewpoint of manufacturing costs, etc., it is preferable to use a strongly acidic cation exchange resin, since it has small volume expansion and contraction, is highly durable, and can be used repeatedly.

[0020] For the layered clay mineral, exfoliated bodies obtained by exfoliating the clay mineral can be used. Such exfoliated bodies may be single-layered, but are usually exfoliated bodies with multiple layers laminated. Such layered clay minerals (exfoliated bodies) are usually flaky and have a thickness of 0.5 nm to 1000 nm. For example, the thickness is 1 nm to 800 nm, 3 nm to 500 nm, 5 nm to 100 nm, or 10 nm to 50 nm. A thinner thickness is preferable as it improves the sealing property. The degree of exfoliation of this exfoliated body is strongly correlated with the thickness of the laminate or the bulk density of the laminate, meaning that the smaller the bulk density, the thinner the exfoliated laminate.

[0021] The first ion exchange step may be carried out simultaneously with the slurry formation step, for example, by introducing and stirring a swellable layered clay mineral and a K-type ion exchange resin into a container. In that case, after carrying out the first ion exchange step, a cation exchange resin removal step for removing the K-type ion exchange resin in the slurry may be carried out. Alternatively, first, a slurry formation step of dispersing a swellable layered clay mineral in a solvent to form a slurry may be carried out, and then the first ion exchange step may be carried out by introducing and passing the formed slurry through a column filled with a K-type ion exchange resin. In that case, since the first cation is exchanged with the second cation when the slurry passes through the column, the cation exchange resin removal step is unnecessary. As described above, the "slurry formation step" and the "first ion exchange step" may be carried out simultaneously or separately. When described herein as "including the slurry formation step and the first ion exchange step", both simultaneous and separate performance of the "slurry formation step" and the "first ion exchange step" are included.

[0022] By exchanging the first cation with the second cation, the resulting layered clay mineral has reduced swelling property, thus improving water resistance. The ratio of exchanging the first cation with the second cation may be appropriately set according to the required degree of non-swelling property. Although not limited, for example, it is sufficient if 20% or more of the first cation is exchanged with the second cation. When the swelling layered clay mineral and the K-type ion exchange resin are charged and stirred in a container, the ratio of the first cation exchanged with the second cation can be adjusted by adjusting the amount of the K-type ion exchange resin charged and the stirring time. Also, when the slurry is charged and passed through a column filled with the K-type ion exchange resin, the time for the slurry to pass through the column can be adjusted by adjusting the size of the column.

[0023] The first embodiment of the method for producing a layered clay mineral has the following effects. (1) As shown in the examples and comparative examples described below, the less the amount of K + ions remaining in the slurry, the more the structural change due to crystal precipitation is suppressed when the sealing material produced from the slurry is used at a high temperature. As a result, since it becomes difficult for the sealing property of the sealing material to deteriorate, a sealing material with high heat resistance can be obtained. In the dehydration by freeze-drying described in Patent Document 2, the K + ions remaining in the slurry are not discharged during the dehydration process. Therefore, the K + ions remaining in the sheet (sealing material) are not reduced. Also, the manufacturing method described in Patent Document 2 requires time for dehydration by freeze-drying, and the manufacturing method described in Patent Document 3 requires time for washing by filtration of the slurry, so there is a problem of poor manufacturing efficiency. On the other hand, in the manufacturing method according to the first embodiment, since a cation exchange resin (K-type ion exchange resin) is used, the K + ions remaining in the slurry after ion exchange are very small. Therefore, the slurry after the first ion exchange step can be used not only in the conventional manufacturing method but also in continuous manufacturing methods for drying the moisture of the slurry, such as the casting method and the doctor blade method. Therefore, the degree of freedom in the manufacturing method of the sheet (sealing material) using the slurry after the first ion exchange step is increased. (2) As described in (1) above, in the first embodiment, a slurry of layered clay mineral with a small amount of remaining K + ions can be obtained. In addition to the use for producing sheets (sealing materials), for example, the slurry itself can also be used as a heat-resistant coating material.

[0024] (Second Embodiment of the Method for Producing Layered Clay Mineral) Next, a second embodiment of the method for producing layered clay mineral will be described. The second embodiment of the method for producing layered clay mineral uses synthetic fluoromica as the swellable layered clay mineral, and after the first ion exchange step, further, using an anion exchange resin, F contained in the slurry after the first ion exchange step - is adsorbed onto the anion exchange resin by performing a second ion exchange step. Except for this, it is the same as the first embodiment of the method for producing layered clay mineral. Therefore, in the second embodiment, the description will focus on the points different from the first embodiment, and the repeated explanations for the matters already described in the first embodiment will be omitted. Thus, even if not explicitly described in the second embodiment, it goes without saying that in the second embodiment, the matters already described in the first embodiment can be adopted.

[0025] When synthetic fluoromica is used as the swellable layered clay mineral, a part of the fluorine in the synthetic fluoromica elutes into the slurry. The fluorine eluted into the slurry has no effect on the heat resistance of the sealing material produced from the slurry. However, in recent years, due to the impact on the environment, there has been a movement to minimize halogens such as fluorine remaining in the product. Also, F - ions are also known to have the potential to corrode stainless steel (Toshio Shibata et al., "Stress Corrosion Cracking Evaluation of Sensitized 304 Stainless Steel in NaF Solution by SSRT", Zairyo-to-Kankyo, 42, 15 - 19 (1993)).

[0026] In the second embodiment of the method for producing layered clay mineral, when synthetic fluoromica is used as the swellable layered clay mineral, after the first ion exchange step, F eluted into the slurry -By performing a second ion exchange step of adsorbing ions onto an anion exchange resin, F ions remaining in the slurry are reduced. -

[0027] The anion exchange resin is not particularly limited as long as it can adsorb F ions contained in the slurry. For example, strongly basic anion exchange resins having a quaternary ammonium group, weakly basic anion exchange resins having a primary to tertiary amino group, etc. can be mentioned. - - The anions exchanged by adsorbing F ions are not particularly limited as long as they do not affect the sealing properties of the sealing material. For example, OH etc. can be mentioned. Considering the pH of the slurry, it is sufficient to appropriately determine whether to use a strongly basic or weakly basic anion exchange resin. -

[0028] Depending on the type of materials used (such as swellable layered clay minerals and solvents), in addition to F ions, anions such as Cl and SO4 may remain in the slurry. When the second ion exchange step is performed, anions such as Cl and SO4 contained in the slurry can also be reduced. Therefore, the second ion exchange step is particularly useful when synthetic fluoromica is used as the swellable layered clay mineral, but it may also be performed when other than synthetic fluoromica is used. Hereinafter, the anions remaining in the slurry such as F, Cl, and SO4 may be collectively described simply as "anions". - - 2- - 2- - - 2-

[0029] ​​​​​​​​​​​It is preferable that the amount of anions contained in the slurry be small. As for how much to remove anions, considering manufacturing costs and the like, the contact time between the slurry and the anion exchange resin may be appropriately adjusted. When the anion exchange resin is charged into and stirred in a container filled with the slurry, after the second ion exchange step, an anion exchange resin removal step for removing the anion exchange resin from the slurry may be carried out. Of course, when the slurry is charged into a column filled with the anion exchange resin and the second ion exchange is carried out, the anion exchange resin removal step is unnecessary.

[0030] The second embodiment of the method for producing a layered clay mineral has the following effects in addition to the effects achieved by the first embodiment. (1) Corrosive F - ions and SO4 2- , F which is a halogen - and Cl - and other anions can be reduced. Therefore, the environmental load can be reduced, and when a sealing material manufactured from the slurry is used, corrosion of flanges and metal pipes can be reduced.

[0031] (Embodiment of the method for producing a sheet containing a layered clay mineral) Next, an embodiment of the method for producing a sheet containing a layered clay mineral will be described. The method for producing a sheet includes a drying step of drying a slurry containing a layered clay mineral produced by the method for producing a layered clay mineral (hereinafter, a sheet produced by the method for producing a sheet containing a layered clay mineral may sometimes be simply referred to as a "sheet"). The drying step is not particularly limited as long as the moisture contained in the slurry can be dried. For example, the slurry may be freeze-dried as described in Patent Document 2 and then formed into a sheet, or the slurry may be directly poured into a mold and dehydrated to produce the sheet in batch units. Further, it may be carried out by drying while continuously spreading the slurry on a flat plate or the like by a casting method, a doctor blade method, or the like (continuous manufacturing method).

[0032] The density of the sheet is preferably 0.5 to 2.5 g / cm 3 , more preferably 1.0 to 2.2 g / cm3 and more preferably 1.2 to 2.0 g / cm 3 . In the present application, a sheet having a density exceeding 1.4 g / cm 3 can be used.

[0033] The sheet preferably has a porosity of 40% or less, more preferably 35% or less, still more preferably 30% or less, and particularly preferably 25% or less when compressed at a surface pressure of 34 MPa. The lower limit is not limited but is usually 1% or more. When the porosity is small, the sealing property is improved. The porosity can be adjusted by the thickness of a single piece of the layered clay mineral or the like. The porosity can be measured by the following method. <Porosity> A sample with a diameter of 30 mm is punched out from the sheet and weighed. Next, the punched-out sample is compressed at a surface pressure of 34 MPa, the thickness at that time is measured, and the volume during compression is determined from the sample size. From the sample weight and the volume during compression, the density during compression is calculated. The true density of the sheet is measured in accordance with JIS R1620. From the density during compression and the true density, the porosity is calculated by the following formula. Porosity (%) = 100 - density during compression / true density × 100

[0034] The sheet may contain, in addition to the layered clay mineral, a binder or the like as long as the effects of the sheet disclosed in the present application are not impaired. The sheet can be composed of 90% by weight or more, 95% by weight or more, 98% by weight or more, or 100% by weight of the layered clay mineral. Also, the sheet can be composed of 90% by weight or more, 95% by weight or more, 98% by weight or more, or 100% by weight of the layered clay mineral and the binder.

[0035] Examples of the binder include, for example, rubber adhesives and the like. More specifically, acrylonitrile-butadiene rubber, styrene-butadiene rubber, polybutadiene rubber, silicone rubber, acrylic rubber, natural rubber, butyl rubber, chloroprene rubber, ethylene-propylene rubber, fluororubber, urethane rubber, acrylic adhesives, silicone adhesives and the like can be mentioned. Among them, acrylonitrile-butadiene rubber and silicone rubber are preferred. By including a binder, flexibility can be imparted to the sheet.

[0036] When a binder is included, the amount of the binder is preferably 0.3 to 20% by weight of the sheet. If it is less than 0.3% by weight, the purpose of imparting flexibility may be insufficient, and if it exceeds 20% by weight, properties such as sealing properties may be impaired. More preferably, it is 0.5 to 15% by weight, and even more preferably, it is 1 to 10% by weight.

[0037] The thickness of the sheet may be appropriately adjusted according to the purpose. Although not limited, for example, about 0.1 to 10 mm can be mentioned.

[0038] The sheet can be used for various industries, exhaust pipes of automobiles, etc., sealing materials for various pipes, for example, gaskets, packings and the like. The sheet may be used as the sealing material itself, or the sheet may be used as a part of the sealing material. Examples of using the sheet as a part of the sealing material include gaskets such as spiral and sawtooth shapes, and laminates in which the sheet is adhered to other members using an adhesive. Examples of other members to which the sheet is adhered include, for example, steel plates, SUS plates, aluminum plates, glass cloths, alkaline earth silicate cloths, expanded graphite sheets, fluororesin sheets and the like.

[0039] (Embodiment of the method for manufacturing a sealing material) Next, with reference to FIGS. 1 to 3, embodiments of a method for manufacturing a sealing material will be described. FIGS. 1 to 3 show an example in which the sealing material is a gasket and a sheet is used as part of the gasket. FIG. 1 is a schematic cross-sectional view of a spiral gasket. FIG. 2 is a schematic cross-sectional view of a sawtooth-shaped gasket installed on a flange. FIG. 3 is a schematic cross-sectional view of a spiral gasket. An embodiment of the method for manufacturing a sealing material includes a step of incorporating a sheet as part of the gasket (hereinafter, may be described as the "incorporation step"). Once the sheet is incorporated as part of the gasket, the sheet may be incorporated at any stage of manufacturing the gasket.

[0040] One or both surfaces of the gasket body portion of the gasket are covered with a sheet containing a layered clay mineral. Examples of the gasket include a spiral gasket including a spiral gasket body portion formed by laminating a hoop material and a filler material and winding them in a spiral shape, or a sawtooth-shaped gasket including a sawtooth-shaped gasket body portion having grooves with a sawtooth cross-section formed on one or both surfaces of the body portion.

[0041] As another type of gasket, an example is given in which a sheet is used for at least a part of the filler material in a spiral gasket body portion formed by laminating a hoop material and a filler material and winding them in a spiral shape.

[0042] As shown in FIG. 1, the spiral gasket 1 has a structure in which a spiral gasket body portion 30 formed by laminating a hoop material 20 and a filler material 10 and winding them in a spiral shape is sandwiched between an outer ring 50 and an inner ring 40. Sheets 70 are laminated on both surfaces of the annular surface (exposed surface) of the spiral gasket body portion 30. Preferably, an inner peripheral empty winding portion 22 around which the hoop material 20 is wound is formed on the inner periphery of the gasket body portion 30. Also preferably, an outer peripheral empty winding portion 24 around which the hoop material 20 is wound is formed on the outer periphery of the gasket body portion 30.

[0043] The spiral gasket may include an inner ring 40 and an outer ring 50 as shown in FIG. 1, or may include only the outer ring 50, or may include only the inner ring 40. Further, although the sheet 70 covers both of the annular surfaces of the gasket main body 30, it may cover only one surface. Furthermore, in FIG. 1, the sheet 70 covers the entire annular surface of the gasket main body 30, but it may cover a part of the gasket main body 30.

[0044] When the surface of the gasket main body is covered with the sheet 70 (incorporation step), the covering method is not particularly limited, but it can be carried out, for example, by using an adhesive such as glue. Also, instead of adhering, it may be sufficient to simply place the sheet on the exposed surface.

[0045] The spiral gasket 1 has its surface of the gasket main body 30 covered with the sheet 70, which improves the compatibility with various pipe joints (flanges) etc. and reduces leakage from the contact surface. In addition, it can prevent the burnout of the filler material, thus improving the sealing performance of the gasket itself.

[0046] As shown in FIG. 2, the serrated gasket 2 has sheets 70 laminated on both surfaces of the annular surface of the serrated gasket main body 60. A plurality of concentric grooves 61 with different diameters are formed in the serrated gasket main body 60. That is, as shown in FIG. 2, grooves 61 are formed between adjacent teeth (serrated teeth) 62.

[0047] The serrated gasket 2 allows the sheet 70 to flow into the groove portion formed between the serrated teeth by tightening, and exhibits excellent sealing performance even at low surface pressure. Also, since the sheet is bonded to the surface (incorporation step), it has good compatibility with the flange surface, and since the tips of the serrated teeth do not directly contact the flange, the flange surface is not damaged.

[0048] The serrated gasket 2 may be provided with an outer ring and / or an inner ring (not shown) in the same manner as the spiral gasket.

[0049] The spiral gasket shown in Fig. 3 is different from the spiral gasket 1 shown in Fig. 1 in that at least a part of the filler material 10 of the spiral gasket 1 contains a sheet and it is not necessary to be covered with the sheet 70. For the same members as the spiral gasket 1 shown in Fig. 1, the same reference numerals are given and the description is omitted.

[0050] The filler material 12 used in the spiral gasket 3 shown in Fig. 3 is a tape-shaped or a plurality of strip-shaped sheets. This sheet is the same as the sheet 70 shown in Fig. 1, but since it is used as the filler material 12, the thickness is usually about 0.05 to 1.0 mm. In the example shown in Fig. 3, all of the filler material 12 is formed of the sheet disclosed in the present application, but a sheet may be used for a part of the filler material 12. The incorporation process may be carried out by overlapping the hoop material 20 and the filler material 12 and winding them in a spiral shape.

[0051] Examples are given below to explain specific examples of the embodiments disclosed in the present application, but they are not intended to limit or restrict the scope of the embodiments disclosed in the present application.

Example

[0052] 1. Production of layered clay mineral and production of sheet <Example 1 (without the second ion exchange step)> [Preparation of K-type ion exchange resin] To 5000 mL of HPR1200 H (manufactured by Organo Corporation), which is an H-type strongly acidic cation exchange resin, 2.0 kg of a 3 mol / L aqueous potassium hydroxide solution was added and stirred for 1 hour. The ion exchange resin was washed with distilled water.

[0053] [Adjustment of slurry] (1) As the swelling layered clay mineral, 1.3 kg of sodium tetrasilicate mica "MEB-1" (manufactured by Katakura Koppu Agri Co., Ltd., 8 wt%), which is synthetic fluoromica, was used, and 4375 mL of the above K-type ion exchange resin was added and stirred for 1 hour. (2) The K-type ion exchange resin was separated using a sieve with an opening of 250 μm. (3) The above (1) and (2) were repeated again. (4) Distilled water was added and stirred to obtain a uniform slurry of layered clay minerals adjusted to a concentration of 5 wt%. (5) While stirring, it was heated and concentrated at a liquid temperature of 80 °C and adjusted to a concentration of 18 wt%. (6) 45 wt% of NBR latex was added so that the solid content of the layered clay mineral : solid content of NBR = 96 : 4, and it was stirred to obtain a uniform slurry.

[0054] [Adjustment of Sheet] The slurry obtained in the above [Adjustment of Slurry] was formed with a doctor blade device and dried at 100 °C for 15 hours to produce a sheet.

[0055] <Example 2 (with a second ion exchange step)> [Preparation of K-type ion exchange resin], [Adjustment of slurry], and [Adjustment of sheet] were carried out in the same procedure as in the above <Example 1>, except that the following (3-1) and (3-2) were carried out between (3) and (4) in the [Adjustment of slurry] of the above <Example 1>.

[0056] (3-1) IRA402BL OH (manufactured by Organo Corporation), which is an anion exchange resin, was added to the slurry formed in (3) above and stirred for 1 hour. (3-2) The anion exchange resin was separated using a sieve with an opening size of 250 μm.

[0057] <Comparative Example 1> [Adjustment of Slurry] (1) As the swelling layered clay mineral, 1.3 kg of sodium tetrasilicate mica "MEB-1" (manufactured by Katakura Koppu Agri Co., Ltd., 8 wt%), which is synthetic fluorine mica, was used, and 0.88 kg of an 11.8 wt% potassium hydroxide aqueous solution was added and stirred. (2) 24 g of 45 wt% NBR latex was added, and it was further stirred so that the slurry became uniform. [Adjustment of Sheet] (1) The slurry was poured onto filter paper set in a dehydration forming device, and a cake was produced by filtration forming. (2) The obtained cake was dried at 100 °C for 2 hours to prepare a sheet.

[0058] <Comparative Example 2> In the procedure (2) of [Slurry Adjustment] of Comparative Example 1, except that 1.0 kg of a 21.8 wt% potassium hydroxide aqueous solution was used instead of 0.88 kg of an 11.8 wt% potassium hydroxide aqueous solution, [Slurry Adjustment] and [Sheet Adjustment] were carried out in the same procedure as in Comparative Example 1.

[0059] <Comparative Example 3> Using the slurry obtained in [Slurry Adjustment] of Comparative Example 1, instead of [Sheet Adjustment] of Example 1, a sheet was prepared by [Sheet Adjustment] of Example 1.

[0060] The following evaluations were performed on the obtained sheets. The results are shown in Table 1. The diagonal column in Table 1 means that the data was not obtained.

[0061] [Water Resistance] A sheet punched to a diameter of 20 mm was immersed in pure water at 25 °C for 24 hours. It was visually judged whether the sheet shape was maintained after immersion. When the shape was maintained, it was marked as ○, and when it was not maintained, it was marked as ×. A photograph after 24 hours is shown in Figure 4.

[0062] [Residual Amount of Alkali Metal Ions] The sheet was pulverized, put into an aluminum cell, pressure-molded, and subjected to fluorescence X-ray analysis (ZSXPrimusII / Rigaku). The analyzed value in terms of oxide was divided by the molecular weight, and the elemental ratio was calculated from the following formula. JPEG0007713906000001.jpg24126

[0063] [Change in Crystal Form] A sheet punched out to a diameter of 20 mm was heated at a rate of 200 °C / hr until it reached 550 °C, and then heated for 15 hours. Also, a sheet punched out to a diameter of 20 mm was heated at a rate of 200 °C / hr until it reached 750 °C, and then heated for 105 hours. The temperature was decreased by natural cooling. Then, platinum sputtering was performed and observation was carried out using a scanning electron microscope. Scanning electron micrographs of the sheets prepared in Example 1, Example 2, and Comparative Example 1 when heated to 550 °C are shown in FIG. 5. Scanning electron micrographs of the sheets prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 when heated to 750 °C are shown in FIG. 6.

[0064] [Amount of eluted fluoride ions] It was measured by absorption analysis using the lanthanum alizarin complexone method.

[0065] 2. Manufacture of sealing material (spiral gasket) and evaluation of sealing performance [Manufacture of sealing material (spiral gasket)] Using the sheets prepared in Example 1 and 2 and Comparative Examples 1 to 3 above, a sealing material was manufactured by the following procedure. (1) A hoop material of a SUS316 thin plate in the form of a tape with a thickness of 0.2 mm and a width of 5.3 mm was drawn into a substantially V shape and then spot welded to the outer peripheral portion of the inner ring made of SUS316. (2) After winding only the hoop material three times, the sheets prepared in Example 1 and 2 and Comparative Examples 1 to 3 were sandwiched as a filler material, overlapped with each other, wound four times, and finally, only the hoop material was wound three times and then spot welded in the same manner as at the start of winding. (3) Finally, an outer ring made of SUS316 was attached to produce a spiral gasket.

[0066] [Method for evaluating sealing performance of spiral gasket] The sealing performance of the spiral gasket was measured by the pressure drop method and evaluated by the leakage amount. Specifically, it was carried out by the following procedure. The results are shown in Table 1. (1) The manufactured spiral gasket was used as a test piece, which was sandwiched between a predetermined flange (RF flange, material: SUSF304, nominal pressure: 150LB, nominal diameter 2·1 / 2, surface roughness Ra = 2.1μm), and tightened with a clamping surface pressure of 78 MPa. (2) To measure the volume inside the flange, nitrogen gas was supplied to the inner diameter side of the test piece so that the internal pressure became 1 MPa, and the valve was closed and sealed. A pipe (206.18 cm 3 ) whose internal volume of the piping container had been measured in advance was connected to this, and the internal pressure was released. The residual pressure at this time was measured, and the internal volume of the piping container was calculated from the following formula. JPEG0007713906000002.jpg47141(3) After performing the above (2), the flange was installed in a high-temperature and high-humidity chamber (Super High Temp Oven SSPH-101, manufactured by Espec Corporation), and in an air atmosphere, the temperature was raised from 40°C at a rate of 5°C / min, (a) The temperature was raised to 550°C and heated and held for 105 hours, (b) The temperature was raised to 750°C and heated and held for 105 hours, and then cooled to near room temperature by natural cooling. Note that the above (a) and (b) use the same sheet of the same example (comparative example), but are heated separately for different spiral gaskets. (4) Next, nitrogen gas was supplied to the inner diameter side of the test piece so that the internal pressure became 1 MPa, the time for the internal pressure to drop to 0.9 MPa was measured, and the leakage amount in the surface direction was calculated from the following formula. Note that all the tests were carried out in a room at 23 ± 0.5°C. JPEG0007713906000003.jpg57136

[0067]

Table 1

[0068] From the results shown in Table 1 and Figures 4 to 6, the following results were confirmed. (1) The Na + ions (the first cation) of the swelling layered clay mineral were replaced with K +By exchanging with ions (divalent cations), the sheets of Examples 1 and 2 and Comparative Examples 1 and 3 had sufficient water resistance. (2) When a sheet was produced by the doctor blade method from the slurry that had undergone the first ion exchange using an aqueous potassium hydroxide (KOH) solution of Comparative Example 3, the amount of K + ions remaining in the sheet was significantly higher compared to Examples 1 and 2. This is because, as in Comparative Example 1, the sheet was produced by the doctor blade method without removing K + ions by dehydration, so the K + ions remaining in the slurry remained in the sheet as they were. On the other hand, in Examples 1 and 2, since the first ion exchange step was carried out using a K-type ion exchange resin, the amount of K + ions remaining in the sheet was extremely small. (3) In Comparative Examples 1 and 2, since the amount of K + ions remaining in the sheet was large, there were more crystal form changes compared to Examples 1 and 2, and as a result, the sealing property deteriorated. From these results, using a K-type ion exchange resin in the first ion exchange step not only has the effect of improving the convenience of sheet production, but also has the combined effect of improving the sealing property (heat resistance) of the produced sheet. (4) The amount of residual alkali metal ions shown in Comparative Example 1 is the K + ions and Na +This is the amount of ions remaining in the sheet even after ion removal. On the other hand, the remaining alkali metal ion amounts in Examples 1 and 2 are considered to directly reflect the amount of ions contained in the slurry after the first ion exchange step, and this amount is even less than that in Comparative Example 1. Therefore, it was confirmed that by using the method for producing a layered clay mineral disclosed in the present application, a slurry with an extremely small amount of alkali metal ions remaining after the first ion exchange step can be provided. For example, by further dehydrating the slurries prepared in Examples 1 and 2, the remaining alkali metal ions contained in the sheet can be further reduced. Therefore, by using the slurry prepared by the method for producing a layered clay mineral disclosed in the present application, the manufacturing method of the sheet can be selected according to the performance required for the sheet (sealing material). (5) From the comparison between Examples 1 and 2, it was confirmed that the F - ions contained in the sheet do not affect the sealing property (heat resistance). Furthermore, by using an anion exchange resin to adsorb the F - ions contained in the slurry after the first ion exchange step onto the anion exchange resin, it was confirmed that the F - ions remaining in the sheet can be reduced.

Industrial Applicability

[0069] The slurry prepared by the method for producing a layered clay mineral disclosed in the present application can be used as a sealing material for sealing fluids such as water, oil, steam, and gas in equipment and various pipe joints in a high-temperature and high-pressure state in petroleum refining, petrochemical plants, LNG plants, power plants, steel mills, etc.

Explanation of Symbols

[0070] 1,3 spiral gasket 2 serrated gasket 10,12 filler material 20 hoop material 30 spiral gasket body part 40 inner ring member 50 outer ring member 60 serrated gasket body part 61 groove 62 tooth 70 sheet 100 flange

Claims

1. A method for producing a layered clay mineral, wherein the method for producing the layered clay mineral comprises: a slurry formation step of dispersing a swellable layered clay mineral in a solvent to form a slurry; A first ion exchange step of exchanging at least a part of the first cations present between the layers of the swellable layered clay mineral with K ＋ ions which are second cations; ＋ and (provided that, except for performing a step of reducing ions in the slurry by treating the slurry with an ion exchange resin or a semipermeable membrane before performing the first ion exchange step). the first ion exchange step is performed using a cation exchange resin; the swellable layered clay mineral is synthetic fluoromica; after the first ion exchange step, further comprising a second ion exchange step; in the second ion exchange step, using an anion exchange resin to adsorb F− ions contained in the slurry after the first ion exchange step to the anion exchange resin A method for producing a layered clay mineral.

2. The cation exchange resin is a strongly acidic cation exchange resin The method for producing a layered clay mineral according to claim 1.

3. further comprising a cation exchange resin removal step of removing the cation exchange resin from the slurry after the first ion exchange step The method for producing a layered clay mineral according to claim 1.

4. further comprising an anion exchange resin removal step of removing the anion exchange resin from the slurry after the second ion exchange step The method for producing a layered clay mineral according to claim 1.

5. A method for producing a sheet containing a layered clay mineral, wherein the method for producing the sheet comprises: a drying step of drying a slurry containing a layered clay mineral produced by the production method according to any one of claims 1 to 4 A method for producing a sheet.

6. The drying step is performed by drying while continuously stretching the slurry The method for producing a sheet according to claim 5.

7. A method for producing a sealing material, wherein the method for producing the sealing material comprises: a step of incorporating a sheet produced by the method for producing a sheet according to claim 5 as a part of a gasket A method for producing a sealing material.

8. A method for producing a sealing material, wherein the method for producing the sealing material comprises: a step of incorporating a sheet produced by the method for producing a sheet according to claim 6 as a part of a gasket A method for producing a sealing material.

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