JP2007051257A - Sealing material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing material which can prevent a cut-through phenomenon, while preventing infiltration leak. <P>SOLUTION: This belt-like sealing material 15 produced by laminating drawn porous polytetrafluoroethylene films 11 and laminating non-porous fluororesin films 12 between the layers of the laminate and/or on the surfaces of the laminate is characterized in that the width W and the thickness t of the belt-like sealing material 15 satisfy a relation of W≥t, and an angle θ formed between the lamination surface 13 of the drawn porous polytetrafluoroethylene film and the width direction of the sealing material is 1 to 45°. The angleθ, the width W, and the thickness t may preferably satisfy the relation of the following expression (1) or (2). W>t/tanθ (1), W>h/sinθ+t/tanθ (2) [(h) is a distance between the non-porous fluororesin films 12]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealing material (such as a gasket) used for sealing a surface contact portion of a flange portion of a pipe or a container (including a tank), a manhole cover, and other industrial equipment.

  In the fields of medicine, food, chemistry, and the like, polytetrafluoroethylene (PTFE) sealing materials having excellent corrosion resistance are widely used for joint portions of pipes through which corrosive fluid flows.

  For example, a sealing material made of unstretched polytetrafluoroethylene (hereinafter sometimes referred to as “sintered PTFE”) manufactured by a sintering method is used. However, since sintered PTFE is hard, it has low conformability (followability) to fine irregularities of the joints (flange, etc.) of the pipe, and a phenomenon called interface leakage in which fluid leaks from the interface between the joint and the seal material occurs. There is a case. In particular, glass-lined joints have relatively large irregularities and are likely to cause interface leakage.

  As a PTFE sealing material excellent in conformability (concave / concave followability), a sealing material made of expanded porous polytetrafluoroethylene (hereinafter sometimes abbreviated as “ePTFE”) has attracted attention. For example, Patent Document 1 discloses a sheet-like gasket in which ePTFE films are laminated. Patent Document 2 discloses a tape-shaped sealing material in which ePTFE is laminated. The sealing material (gasket) currently disclosed by these patent documents 1-2 is shown in FIG.1 and FIG.2. FIG. 1 is a partially cutaway schematic perspective view showing a state in which a sealing material (gasket) 10 is attached to a flange 20, and FIG. 2 is an enlarged sectional view showing a seal portion. As shown in FIGS. 1 and 2, the sealing material 10 of Patent Documents 1 and 2 is laminated so that the ePTFE film 11 is parallel to the flange surface 21. The sealing material 10 made of ePTFE is softer than that made of sintered PTFE, can be easily deformed in the thickness direction of the sealing material 10, and can prevent leakage from the flange surface 21 (interface leakage). However, since the ePTFE film 11 has a porous structure, there is a risk of leakage (penetration leakage) passing through the inside of the sealing material 10.

Therefore, in Patent Document 3, as shown in FIG. 3, the ePTFE film 11 is laminated so as to be orthogonal to the flange surface 21. Thus, if the ePTFE film 11 is orthogonally crossed with respect to the flange surface 21, the penetration leak can be prevented by inserting the dense PTFE 12 therebetween.
Japanese Utility Model Publication No. 3-89133 (Claim 1, FIG. 3) US Pat. No. 5,964,465 (FIG. 4) JP 2002-243041 A

  However, if the ePTFE film 11 is orthogonal to the flange surface 21, as shown in FIG. 4, when the flange 20 is tightened, the ePTFE film 11 is buckled by the pressing force, and the width of the gasket is widened. There is. If the width of the gasket is widened, the tightening pressure on the seal surface may be reduced, causing interface leakage. Moreover, if the gasket protrudes into the piping, there is a concern that the fluid flow may be disturbed. Further, in the case of a flange having a large unevenness such as a glass lining flange, the tightening load is concentrated on the convex portion 22 of the flange as shown in FIG. Therefore, depending on the size of the protrusion 22 and the tightening load, the gasket 10 may be torn in the width direction (this phenomenon is referred to as “cut-through phenomenon”).

  The present invention has been made by paying attention to the above-described circumstances, and its purpose is to provide a sealing material capable of preventing the spread phenomenon of the gasket (particularly the cut-through phenomenon) while suppressing permeation leakage. There is to do.

  As a result of intensive studies to solve the above problems, the inventors of the present invention laminated the ePTFE film so that the ePTFE film 11 is inclined with respect to the flange surface 21, and between the layers and / or the surface of the laminate. Furthermore, when a non-porous fluororesin film (such as dense PTFE) is laminated, it has been found that the penetration of the sealing material in the width direction can be suppressed while preventing permeation leakage, and the present invention has been completed.

  That is, in the band-shaped sealing material of the present invention, a stretched porous polytetrafluoroethylene film is laminated, and a nonporous fluororesin film is laminated between the layers and / or the surface of the laminate. In the present invention, the width W and the thickness t of the belt-shaped sealing material satisfy the relationship of W ≧ t, and the laminated surface of the stretched porous polytetrafluoroethylene and the width direction of the sealing material are formed. The angle θ is 1 to 45 °.

The angle θ, the width W, and the thickness t may preferably satisfy the relationship of the following formula (1) or formula (2).
W> t / tan θ (1)
W> h / sin θ + t / tan θ (2)
(In the formula, h represents an interval between nonporous fluororesin films)
The strip-shaped sealing material may be formed in a closed ring shape by connecting a start end and a termination end in the longitudinal direction.

  The strip-shaped sealing material is, for example, (1) stretched porous polytetrafluoroethylene so that a nonporous fluororesin film is disposed between and / or on the surface of a laminate of stretched porous polytetrafluoroethylene films. The film and the nonporous fluororesin film are laminated, and (2) while maintaining the angle formed by the laminated surface of the obtained laminate and the slit blade at a predetermined angle θ (where θ = 1 to 45 °) The laminate can be manufactured by slitting at a predetermined interval t. When the width of the slit body is wide, while maintaining a predetermined interval W along a plane that is substantially parallel to the polytetrafluoroethylene laminate line appearing on the slit surface of the slit body and substantially perpendicular to the slit surface. And the said strip | belt-shaped sealing material can be manufactured by further slitting the said slit body, satisfying the relationship of W> = t.

  According to the sealing material of the present invention, the angle θ formed by the laminating surface of the ePTFE film and the width direction of the sealing material is set to 1 to 45 °, and the nonporous fluororesin is formed between the layers and / or the surface of the ePTFE film laminate. Since the films are laminated, the penetration leakage can be prevented while suppressing the spread of the sealing material in the width direction.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

[Sealant]
FIG. 6 is a schematic perspective view showing an example of the strip-shaped sealing material of the present invention.
6 has a laminated porous polytetrafluoroethylene (ePTFE) film 11 laminated thereon, and a non-porous fluororesin film (dense PTFE film in the illustrated example) so as to be parallel to the ePTFE film. 12 is inserted. As shown in FIG. 7, the strip-shaped sealing material 15 is used by attaching a flange surface 21 after connecting a longitudinal start end 14 a and a termination end 14 b to form a closed ring.

  In the present invention, the width W and the thickness t of the strip-shaped sealing material 15 satisfy the relationship of W ≧ t, and the laminated surface 13 of the ePTFE film 11 and the width (W) direction of the sealing material 15 are It is important that the angle θ to be formed is in the range of 1 to 45 °. When the ePTFE film 11 is inclined with respect to the flange surface 21 as described above, the spread of the sealing material in the width direction can be suppressed, and the cut-through phenomenon can be prevented. Further, since a non-porous fluororesin film (such as a dense PTFE film) 12 is interposed between the ePTFE films 11 laminated in an inclined manner, permeation leakage can be prevented.

In order to reliably prevent permeation leakage, it is desirable that the nonporous fluororesin film 12 penetrates from the bottom surface to the top surface of the sealing material 15. As shown in the cross-sectional view of FIG. 8, in order for the nonporous fluororesin film 12 to penetrate from the bottom surface 16 to the top surface 17, a length of t / tan θ is necessary in the width direction. It is desirable that W satisfies the following formula (1a).
W> t / tan θ (1a)

  The thickness t of the sealing material 15 is usually set in the range of about 0.5 mm or more (preferably 1 mm or more, more preferably 1.5 mm or more), 10 mm or less (preferably 7 mm or less, more preferably 5 mm or less). it can.

  The non-porous fluororesin film 12 does not necessarily need to be interposed between the layers of the laminate of the PTFE film 11, and may be disposed (laminated) on the surface of the laminate. It may be provided (laminated).

  Further, the nonporous fluororesin film 12 may be a single sheet or a plurality of sheets. When the belt-shaped sealing material 15 is manufactured by a mass production method described later, a plurality of nonporous fluororesin films 12 are arranged (laminated) with a predetermined interval.

In the mass production type band-shaped sealing material 15 in which a plurality of non-porous fluororesin films 12 are arranged at predetermined intervals, the non-porous fluororesin film 12 remains on the bottom surface 16 even when the width W of the sealing material 15 is t / tan θ. To the upper surface 17 in some cases. For example, in the example shown in the cross-sectional view of FIG. 9, the nonporous fluororesin film 12 is exposed to the side surface 18 in the middle and does not penetrate from the bottom surface 16 to the top surface 17. In order to ensure penetration regardless of the arrangement position, in addition to the t / tan θ, h / sin θ (where h represents the interval between the nonporous fluororesin films 12), the sealing material It is necessary to increase the width W of 15 (see FIG. 10). That is, the width W of the sealing material 15 needs to satisfy the relationship of the following formula (2a).
W> h / sin θ + t / tan θ (2a)

  The interval h is, for example, about 10 mm or less, preferably about 7 mm or less, and more preferably about 5 mm or less. As the interval h is made smaller, penetration leakage can be prevented more reliably. Furthermore, the lower limit of the width W that satisfies the expression (2a) can be lowered, and the sealing material 15 can be easily designed. However, if the distance h is too small, the flexibility of the sealing material 15 decreases. Therefore, it is recommended that the interval h be, for example, 1 mm or more, preferably 1.5 mm or more, more preferably 2 mm or more.

  Note that the sealing material 15 of the present invention does not necessarily satisfy the relationship of the formula (2a). If the formula (2a) is satisfied, the non-porous fluororesin film 12 penetrates from the bottom surface 16 to the top surface 17 with a probability of 100%. However, since the width becomes thick, the manufacturing cost per one increases. Also, the types of flanges that can be applied are reduced. Therefore, the width of the sealing material 15 may be determined by comparing these merits and demerits.

Although there is a demerit that the width is further increased, the formula (1a) and the formula (2a) are rewritten as follows when the risk of seepage leakage is further reduced.
W> t / tan θ + ΔW (1b)
W> h / sin θ + t / tan θ + ΔW (2b)

  In the equation, ΔW indicates a margin (safety) when setting the width W, and it is assumed that a problem that may occur when the sealing material 15 is attached to the flange 20 is ensured even if the problem occurs. This is a term added for the purpose of preventing permeation leakage. This ΔW will be described in more detail with reference to FIGS. 11 and 12. 11 is a schematic cross-sectional view showing an example of a state in which the sealing material 15 of FIG. 8 is attached to the flange 20, and FIG. 12 is a schematic cross-sectional view showing an example of a state in which the sealing material 15 of FIG. is there. Both of the illustrated examples are based on the possibility that portions (ΔWa, ΔWb) that are not in contact with the flange surface 21 may occur on both the outer peripheral side and the inner peripheral side of the sealing material 15. And if this non-contact part part generate | occur | produces, even if the width | variety W is set like said Formula (1a), (2a), an osmosis | permeation leak may arise. Therefore, in the formulas (1b) and (2b), the width W of the sealing material 15 is the minimum value obtained from the formula (1a) or the formula (2a) (t / tan θ in the case of the formula 1a; h / sin θ + t in the case of the formula 1b. / Tan θ) is made wider by the total length of the non-contact portion (ΔWa + ΔWb = ΔW). Thus, if the width W of the sealing material 15 is increased, the non-porous fluororesin film 12 can function more reliably even if a non-contact portion occurs, and the permeation leakage can be prevented more reliably.

  The larger the ΔW (safety) is set, the more reliably the permeation leakage can be prevented. On the other hand, the upper limit of the width W of the sealing material 15 is restricted according to the width of the flange surface and the like, and if ΔW is excessively increased, the manufacturing cost of the sealing material increases. Accordingly, ΔW is set within a range of, for example, 0.5 mm or more (particularly 1 mm or more) or 5 mm or less (particularly 3 mm or less).

  Further, it is recommended that the strip-shaped sealing material 15 of the present invention has a ratio of thickness t to width W (t / W) of, for example, 0.05 or more (preferably 0.1 or more, particularly 0.12 or more). Is done. If the ratio t / W is too small, the belt-like sealing material 15 tends to stand up with respect to the flange surface 21 when the belt-like sealing material 15 is annularly attached to the flange surface 21, and it is difficult to maintain a flat state. Become. On the other hand, the greater the ratio t / W, the easier the ePTFE film 11 buckles when the flange is tightened. Therefore, the ratio t / W is preferably 1 or less, more preferably 0.5 or less, and particularly 0.3 or less.

By the way, when the relationship of the formula (1a) is satisfied, as is clear from the formula (1a), the ratio t / W is less than tan θ. Therefore, if θ is set so that tan θ is 1 or less (preferably 0.5 or less, particularly 0.3 or less), t / W is within the above range (1 or less, more preferably 0.5 or less, especially 0.3 or less). From the above, θ is 45 ° (= tan ⁻¹ 1) or less, more preferably 27 ° (≈tan ⁻¹ 0.5) or less, particularly 17 ° (≈tan ⁻¹ 0.3) or less. Recommended.

Further, when the relationship of the formula (1a) is satisfied, tan θ must be greater than t / W. Therefore, when t / W is within the above range (0.05 or more, preferably 0.1 or more, particularly 0.12 or more), tan θ is also the same numerical range (0.05 or more, preferably 0.1 or more, particularly 0.12 or more). Therefore, θ needs to be 2 ° (≈tan ⁻¹ 0.05) or more, preferably 5 ° (≈tan ⁻¹ 0.1) or more, preferably 6 ° (≈tan ⁻¹ 0.12) or more. is there.

  When satisfying the relationship of the expression (2a), if θ is small, the width W may become very large, which may be inconvenient. Therefore, it is recommended that θ is preferably 10 ° or more (particularly 15 ° or more).

  The sealing material of the present invention is not limited to a belt-like material, and may be a closed ring material. This closed annular seal material can be manufactured by connecting the longitudinal direction start end 14a and the end end 14b of the strip-shaped seal material. In this strip-shaped sealing material, the width direction of the sealing material is parallel to the flange surface 21.

  The ring shape of the closed annular seal material is not particularly limited, and can be appropriately designed depending on the shape of the surface to be sealed (flange surface, etc.). For example, the ring shape (circular, elliptical, track shape, etc.) It may be any of an annular shape (rectangular shape etc.).

  In the sealing material of the present invention, the ePTFE film 11 is formed by mixing and molding a fine powder of polytetrafluoroethylene (PTFE) and a molding aid, removing the molding aid, stretching at a high temperature and a high speed, and further required. It refers to a film obtained by firing. The ePTFE film 11 may be uniaxially stretched or biaxially stretched. Microscopically, a uniaxially stretched PTFE film has fine island-like nodes (folded crystals) that are substantially perpendicular to the stretch direction, and interdigital fibrils that connect the nodes (the folded crystals are unwound by stretching). There is a microscopic feature in that the linear molecular bundle drawn out in this manner is oriented in the stretching direction. In addition, the biaxially stretched PTFE film has a spider web-like fibrous structure in which fibrils spread radially, nodes connecting the fibrils are scattered in islands, and there are many spaces defined by the fibrils and nodes. There are microscopic features in the points.

  The average pore diameter of the ePTFE film 11 can be appropriately set according to the draw ratio, and is, for example, 5.0 μm or less, preferably 1.0 μm or less. As the average pore size is reduced, the lamination adhesion between the films can be increased, and the permeation leakage can be reduced. The lower limit of the average pore diameter is not particularly limited, but is usually 0.05 μm or more (particularly 0.5 μm or more). If the average pore diameter of the ePTFE film 11 is less than 0.05 μm, the flexibility of the sealing material is impaired and the sealing performance may be deteriorated. The average pore diameter is a value measured using a Coulter Porometer manufactured by Coulter Electronics.

The porosity of the ePTFE film 11 can also be appropriately set according to the draw ratio, and is, for example, 10% or more, preferably 30% or more. When the porosity of the ePTFE film 11 is less than 10%, the flexibility of the sealing material is impaired, and the sealing performance may be deteriorated. The sealing material 15 can be softened as the porosity increases. However, the larger the porosity, the more likely the penetration leakage occurs. Therefore, the upper limit of the porosity is, for example, 95% or less, preferably about 85% or less. The porosity is calculated from the following formula based on the apparent density ρ _{1 of} PTFE film (unit: g / cm ³ , measured according to JIS K 6885) and the density ρ _{2 of} PTFE (2.2 g / cm ³ ). Is a value calculated based on
Porosity (%) = (ρ ₂ −ρ ₁ ) / ρ ₂ × 100

  The thickness of the ePTFE film 11 is not particularly limited, and is, for example, about 5 μm or more (particularly 15 μm or more) and 200 μm or less (particularly 100 μm or less). When the thickness of the ePTFE film 11 is less than 5 μm, the number of laminated ePTFE films for obtaining a sealing material having a predetermined thickness t increases, and the productivity decreases. Further, when the thickness of the ePTFE film 11 exceeds 200 μm, the number of laminated ePTFE films for obtaining a seal material having a predetermined thickness t is reduced, and the position and number of the nonporous fluororesin film 12 are restricted. Occurs.

  Examples of the fluororesin used for the nonporous fluororesin film 12 include PTFE, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). . A preferred fluororesin is PTFE. Examples of non-porous PTFE films include sintered PTFE films, unstretched PTFE films, and ePTFE films that have been densified by compression or the like (dense PTFE film). A preferred nonporous PTFE film is a dense PTFE film. Non-porous (dense) means that the through-holes are reduced to the extent that fluid cannot permeate, and is a concept different from the porosity.

  It is desirable that an adhesive layer is formed on the bottom surface 16 and / or the top surface 17 of the sealing material of the present invention (such as the belt-shaped sealing material 15, its closed ring body, and closed ring sealing material). If the adhesive layer is formed, the sealing material can be easily attached to the surface to be sealed. The adhesive layer is not particularly limited as long as the sealing material can be fixed to the surface to be sealed, but an adhesive is preferable because the sealing material can be reattached. As the pressure-sensitive adhesive, conventionally known pressure-sensitive adhesives such as acrylic and rubber can be used, but acrylic pressure-sensitive adhesives are preferable because they are excellent in heat resistance. Although a liquid thing may be apply | coated as an adhesive and a sheet | seat or a tape-like thing may be affixed, the adhesive tape laminated | stacked on the release paper is used preferably. Adhesive tape has the advantage that it can be easily attached to the sealing material in the manufacturing process of the sealing material, and it can be applied while peeling the release paper when the sealing material is applied to the surface to be sealed. Therefore, there is an advantage that handling is easy. The width of the adhesive layer can be set, for example, within a range of about 2/3 or less (preferably 1/2 or less) and 1/10 or more (preferably 1/4 or more) with respect to the width W of the sealing material. When the width of the adhesive exceeds 2/3 of the width W of the sealing material, the adhesive layer easily comes into contact with the fluid, and the sealing performance may be lowered depending on the heat resistance and chemical resistance of the adhesive layer itself. If the width of the adhesive layer is less than 1/10 of the width W of the sealing material, the adhesiveness may not be exhibited so as to facilitate the pasting operation.

[Method of manufacturing sealing material]
The strip-shaped sealing material 15 of the present invention can be mass-produced, for example, as shown in FIG. That is, in the example of FIG. 13, the laminated body of ePTFE films has a narrow width and looks like a band when viewed from above (that is, when the width of the band-shaped sealing material 15 is W, the width is W × cos θ The laminated body 31) is used. The strip-shaped laminate 31 can be manufactured by laminating the ePTFE film 11 while sandwiching the nonporous fluororesin film 12 and then cutting it to a predetermined width W × cos θ. Alternatively, the ePTFE film 11 having a width W × cos θ can be manufactured by laminating the nonporous fluororesin film 12 with the non-porous fluororesin film 12 interposed therebetween. The belt-like sealing material 15 can be formed by slitting the belt-like laminate 31 at a predetermined interval t while keeping the angle formed by the laminated surface of the obtained belt-like laminate 31 and the slit blade 34 at a predetermined value θ. In the illustrated example, the band-shaped laminate 31 is directed to the side at an angle θ (θ is an angle between the tilted ePTFE laminate surface and the pre-tilt ePTFE laminate surface), and the laminate surface before the tilt (non-tilt) The belt-shaped sealing material 15 is manufactured by slitting with a slit blade (slit surface) 34 parallel to the surface) while maintaining a predetermined interval t. The slit blade 34 is predetermined with respect to the laminated surface of the ePTFE film. The slit may be made while the angle θ is inclined and the interval between the slit blades 34 is kept at t. Further, after the slit, as shown in FIG. 14, both side portions 33, 33 of the slit body 32 may be trimmed as necessary.

  The strip-shaped sealing material 15 can be mass-produced not by using the strip-shaped laminate 31 having a width of W × cos θ but using a laminate having a width wider than that of the strip-shaped laminate 31. 15-17 is a figure for demonstrating the manufacturing method of the strip | belt-shaped sealing material 15 using the wide laminated body 41. FIG. In the method of this illustrated example, a wide laminate 41 is manufactured by laminating the ePTFE film 11 while sandwiching the nonporous fluororesin film 12. As shown in FIG. 15, the slit blade (first slit surface) 42 is inclined at a predetermined angle θ with respect to the laminated surface 13 of the ePTFE film 11 and the interval between the slit blades (first slit surface) 42 is set to t. The first slit body 43 as shown in FIG. 16 can be manufactured by slitting the laminated body 41 while maintaining the above. Next, a surface 44 which is substantially parallel to the ePTFE laminated line 13 appearing on the slit surface 42 of the first slit body 43 and is substantially orthogonal to the slit surface 42 is set as the second slit surface 44, and this second The second slit body 45 as shown in FIG. 17 can be manufactured by further slitting the first slit body 43 while maintaining the predetermined interval W along the slit surface 44. The second slit body 45 corresponds to the above-described band-shaped sealing material 15.

  In addition, the above-mentioned laminated body (the strip | belt-shaped laminated body 31, the wide laminated body 41, etc.) is normally manufactured by heat-processing (baking process etc.), after laminating | stacking each film. Each film can be integrated by heat treatment.

  The belt-like sealing material 15 may be used as it is attached to the surface to be sealed, or may be processed into a closed annular sealing material in advance. When the belt-like sealing material 15 is used by being attached to the surface to be sealed, the belt-like sealing material is attached along the surface to be sealed while being bonded with an adhesive such as an adhesive tape, and finally the longitudinal direction start and end of the sealing material are attached. Connect and close the ring. The connection method for closing the ring is not particularly limited, but it is preferable to connect the strip-shaped sealing material 15 by cutting the starting end and the terminal end so as to form a taper and overlapping the tapered surfaces. In this case, the connecting portion is integrated by tightening pressure, but may be connected by adhesion using an adhesive or an adhesive tape.

  The closed annular seal material can be manufactured by connecting the longitudinal start and end of the strip-shaped seal material 15. For connection, a known technique such as heat fusion, ultrasonic fusion, adhesion with an adhesive or a pressure-sensitive adhesive can be used. Further, the connecting portion may be subjected to a taper process or the like as necessary.

  Since the sealing material of the present invention as described above can prevent the spread of the width of the sealing material while suppressing permeation leakage, and can also prevent the cut-through phenomenon, in addition to the flange surface 21, various fastening surfaces (particularly, It can be advantageously used to seal glass linings.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

Example 1
(1) Production of ePTFE Film 11 Solvent naphtha (22 parts by weight) was mixed with 100 parts by weight of polytetrafluoroethylene powder (fine powder) obtained by emulsion polymerization, and the obtained paste resin was formed into a film. The molded body is heated to a temperature higher than the boiling point of the solvent naphtha (in this example, 200 ° C.) to evaporate and remove the solvent naphtha, and then biaxially at a temperature lower than the melting point of polytetrafluoroethylene (in this example, 300 ° C.). The ePTFE film 11 having a thickness of 60 μm and a porosity of 80% was prepared by stretching (stretching ratio in the take-up direction: 2 times, draw ratio in the direction orthogonal to the take-up direction: 10 times). The stretching was performed at a speed at which the film extended at a rate of 10% or more per second (about 10% in this example).

(2) Manufacture of non-porous fluororesin film 12 The above ePTFE films are stacked three times, and the pressure is applied (2.4 kN / cm) and temperature (70 ° C.) with a roll to crush the pores. A dense ePTFE film (non-porous fluororesin film) 12 having a thickness of 50 μm was prepared.

(3) Production of Laminate 41 A laminate was produced using the ePTFE film 11 and the nonporous fluororesin film 12 as shown in FIGS. That is, the ePTFE film 11 was wound 220 times in total on a stainless steel hollow mandrel 50 having an outer diameter of 1,000 mm. However, first, the nonporous fluororesin film 12 is wound once, and thereafter, every time the ePTFE film 11 is wound 55 times, the nonporous fluororesin film 12 is inserted for one turn, so that a total of four turns ( 4 layers of nonporous fluororesin film 12 was laminated.

The wound body 51 thus produced was placed in an oven and baked at 365 ° C. for 60 minutes. After firing, the wound body 51 was taken out of the oven and cooled to room temperature. When the inner diameter is D ₁ , the outer diameter is D ₂ , and the axial length is L ₁ , the shape of the wound body 51 is about 1,000 mm (D ₁ ) × 1,020 mm (D ₂ ). × 1,500 mm (L ₁ ) (see FIG. 18).
After cooling, the wound body 51 was cut open in the axial direction to obtain a flat plate body 52 of about 1,500 mm (L ₁ ) × 3,000 mm (L ₂ ) × 10 mm (L ₃ ) (see FIG. 19).

The flat plate 52, while the distance L ₁ direction 50 mm, by cutting the L ₂ direction, the cutting body 53 about _{50mm (L 1) × 3,000mm (} L 2) × 10mm (L 3) Obtained (see FIG. 20). The cut 53 using six, by thermocompression bonding in the laminating direction (L ₃ direction) Again a temperature above the melting point of PTFE of ePTFE film, about _{50mm (L 1) × 3,000mm (} L 2) A laminated body 41 of × 50 mm (L ₃ ) was obtained (see FIG. 21). The reason why the length L ₃ is 50 mm instead of 60 mm (= 10 mm × 6) is due to the pressure of pressure bonding.

(4) Manufacture of the strip-shaped sealing material 15 The laminated body 41 obtained as described above is inclined at an angle θ (θ = 5 ° in Example 1) with respect to the slit blade 42 and slit at intervals of 3 mm (FIG. 22). reference). By trimming both side portions of the obtained slit body and slitting again with a width of 20 mm (see FIGS. 22 and 17), a belt-like sealing material 15 was obtained.

Examples 2-4 and Comparative Examples 1-2
The angle θ between the laminate 41 and the slit blade 42 is set to 15 ° (Example 2), 30 ° (Example 3), 45 ° (Example 4), 0 ° (Comparative Example 1), or 90 ° (Comparison). Except for Example 2), a strip-shaped sealing material 15 was produced in the same manner as in Example 1.

  The buckling resistance and cut-through resistance of the strip-shaped sealing material obtained as described above were examined by Test 1 and Test 2 below.

[Test 1]
The strip-shaped sealing material 15 was cut to a length of 100 mm, and a load of 40 kN (about 20 MPa in terms of surface pressure) was applied in the thickness t direction for 60 minutes at room temperature. The width W ′ and the thickness t ′ of the sealing material after unloading were measured, and the compression characteristic Z and the flow characteristic K were obtained based on the following formula.
Z = t ′ / t × 100
(T 'indicates the thickness of the sealing material after the test, and t indicates the thickness of the sealing material before the test)
K = W'-W
(W ′ indicates the width of the sealing material after the test, and W indicates the width of the sealing material before the test)
It can be said that the greater the compression characteristic Z is, the less buckling occurs, and the smaller the flow characteristic K is, the less likely that cut-through occurs.

[Test 2]
A double-sided adhesive tape [manufactured by Sumitomo 3M Co., Ltd., “# 9458”] was affixed to the bottom surface of the belt-shaped sealing material 15. The strip-shaped sealing material 15 was mounted on the surface to be sealed 26 of the platen 25 shown in FIG. 23 while peeling the release paper of the double-sided adhesive tape affixed to the strip-shaped sealing material 15. The center of the strip-shaped sealing material 15 is substantially along the φ240 mm line of the sealing surface 26, and the start and end of the strip-shaped sealing material 15 are joined with a double-faced transfer tape [Sumitomo 3M Co., Ltd., “# 9458”]. The ring was closed (inner diameter 220 mm, outer diameter 260 mm). The start end and the end end are preliminarily taper cut at an angle of 30 ° in order to facilitate joining of the end portions.

  After affixing the sealing material 15, a platen having the same shape was placed and the sealing material 15 was sandwiched. These were set on a press plate heated to 200 ° in advance, and a load of 157 kN (about 20 MPa in terms of surface pressure) was applied for 30 minutes, and the presence or absence of a cut-through phenomenon was visually confirmed.

The results are shown in Table 1 and FIG.

  As is apparent from Table 1 and FIG. 24, the cut-through phenomenon and the buckling phenomenon are less likely to occur as the angle θ decreases. However, when the angle θ is 0 °, it is not possible to prevent permeation leakage. Therefore, it can be said that the angle θ is preferably about 1 to 45 °.

FIG. 1 is a schematic perspective view showing an example of a conventional sealing material. FIG. 2 is a partially enlarged sectional view of FIG. FIG. 3 is a schematic sectional view showing another example of a conventional sealing material. FIG. 4 is a schematic cross-sectional view showing an example of a usage state of the sealing material of FIG. FIG. 5 is a schematic cross-sectional view showing another example of the usage state of the sealing material of FIG. FIG. 6 is a schematic perspective view showing an example of the strip-shaped sealing material of the present invention. FIG. 7 is a schematic perspective view showing an example of a usage state of the strip-shaped sealing material of FIG. FIG. 8 is a schematic cross-sectional view showing another example of the strip-shaped sealing material of the present invention. FIG. 9 is a schematic cross-sectional view showing still another example of the strip-shaped sealing material of the present invention. FIG. 10 is a schematic cross-sectional view showing another example of the strip-shaped sealing material of the present invention. FIG. 11 is a schematic cross-sectional view showing still another example of the strip-shaped sealing material of the present invention. FIG. 12 is a schematic sectional view showing another example of the belt-like sealing material of the present invention. FIG. 13 is a first schematic view (perspective view) showing an example of a method for producing a strip-shaped sealing material of the present invention. FIG. 14 is a second schematic view (perspective view) showing an example of a method for producing the belt-shaped sealing material of the present invention. FIG. 15 is a first schematic view (perspective view) showing another example of the method for producing the strip-shaped sealing material of the present invention. FIG. 16 is a second schematic view (perspective view) showing another example of the method for producing the strip-shaped sealing material of the present invention. FIG. 17 is a third schematic view (perspective view) showing another example of the method for producing the strip-shaped sealing material of the present invention. FIG. 18 is a first view (perspective view) for explaining a method of manufacturing the belt-shaped sealing material of the embodiment. FIG. 19 is a second view (perspective view) for explaining the manufacturing method of the belt-shaped sealing material of the embodiment. FIG. 20 is a third view (perspective view) for explaining the method for manufacturing the belt-shaped sealing material of the embodiment. FIG. 21 is a fourth view (perspective view) for explaining the method for manufacturing the belt-shaped sealing material of the embodiment. FIG. 22 is a fifth view (perspective view) for explaining the method for manufacturing the belt-shaped sealing material of the embodiment. FIG. 23 is a two-view drawing (plan view, side view) for explaining a test method for the strip-shaped sealing material obtained in the example. FIG. 24 is a graph showing the relationship between the predetermined angle θ, the compression characteristic Z, and the flow characteristic K in the belt-shaped sealing material.

Explanation of symbols

11: Stretched porous polytetrafluoroethylene (ePTFE) film 12: Nonporous fluororesin film 13: ePTFE film laminated surface 14a: Start end 14b of strip-shaped seal material 15: End of strip-shaped seal material 15: Strip-shaped seal material 31: Strip-shaped laminate Body 41: Laminated bodies 34, 42, 44: Slit blade (slit surface)
43: 1st slit body

Claims (9)

A stretched porous polytetrafluoroethylene film is laminated, and a non-porous fluororesin film is laminated on the interlayer and / or the surface of the laminate,
The width W and the thickness t of the strip-shaped sealing material satisfy the relationship of W ≧ t, and the angle θ formed by the laminated surface of the stretched porous polytetrafluoroethylene film and the width direction of the sealing material is A strip-shaped sealing material characterized by being 1 to 45 °. The strip-shaped sealing material according to claim 1, wherein the angle θ, the width W of the sealing material, and the thickness t of the sealing material satisfy the relationship of the following formula (1).
W> t / tan θ (1) A plurality of the non-porous fluororesin films are laminated while maintaining a predetermined interval h,
The strip-shaped sealing material according to claim 1, wherein the interval h, the angle θ, the width W of the sealing material, and the thickness t of the sealing material satisfy the relationship of the following formula (2).
W> h / sin θ + t / tan θ (2)   The strip | belt-shaped sealing material of Claim 3 whose said space | interval h is selected from the range of 1-10 mm.   The band-shaped sealing material according to any one of claims 1 to 4, wherein the angle θ is 15 to 45 °.   A closed annular seal material in which the longitudinal direction start and end of the belt-shaped seal material according to claim 1 are connected to form a closed annular shape. A closed annular sealing material in which a stretched porous polytetrafluoroethylene film is laminated, and a nonporous fluororesin film is laminated on the interlayer and / or the surface of the laminate,
An angle θ formed by the width W and the thickness t of the closed annular band sealing material satisfying the relationship of W ≧ t, and the laminated surface of the expanded porous polytetrafluoroethylene and the width direction of the sealing material are formed. Is 1 to 45 °, a closed annular seal material. Laminated porous polytetrafluoroethylene film and nonporous fluororesin film are laminated so that a nonporous fluororesin film is disposed between and / or on the surface of the laminate of stretched porous polytetrafluoroethylene film The manufacturing process for the belt-like laminate
A slit process for slitting the belt-like laminate at a predetermined interval t while maintaining the angle formed by the laminated surface of the obtained belt-like laminate and the slit blade at a predetermined angle θ selected from a range of 1 to 45 °,
A method for producing a strip-shaped sealing material including: Laminated porous polytetrafluoroethylene film and nonporous fluororesin film are laminated so that a nonporous fluororesin film is disposed between and / or on the surface of the laminate of stretched porous polytetrafluoroethylene film Laminate manufacturing process,
A first slitting step of slitting the laminated body at a predetermined interval t while maintaining an angle formed by the laminated surface of the obtained laminated body and the slit blade at a predetermined angle θ selected from a range of 1 to 45 °;
After the slit body is manufactured by the first slit process, a predetermined interval W is set along a plane that is substantially parallel to the polytetrafluoroethylene laminated line appearing on the slit surface of the slit body and substantially orthogonal to the slit surface. A second slitting step for further slitting the slit body while maintaining and satisfying the relationship of W ≧ t,
A method for producing a strip-shaped sealing material including:

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