JP2007107619A - Pipe arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe arrangement which allows damage detection by securing continuity between a nail or the like and a conductive member when the nail is hammered in. <P>SOLUTION: The pipe arrangement 1 is composed by providing an insulating inner layer 2, and a conductive or semiconductive outer layer 3 covering at least one part of a surface of the inner layer 2. The outer layer 3 is composed by including an elastic body. For example, the elastic body composing the outer layer 3 is formed by conductive rubber or a fiber structure body, and a reinforcement is attached to its inner side as needed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pipe disposed under a floor of a building, and more particularly to a pipe capable of detecting damage that may occur in the pipe when nails or screws are driven.

  In recent years, as water pipes for water supply or hot water supply that are arranged under the floors of various buildings such as apartment houses, instead of conventional metal water pipes, resin water pipes formed of cross-linked polyethylene or the like have been used. It has become widespread. This resin water pipe is less expensive than metal water pipes, has many advantages that it is lightweight, excellent in workability, and does not cause metal rust.

  On the other hand, resin water pipes have poor penetration strength compared to metal water pipes, so various fixtures such as nails and screws for fixing floor boards etc. were mistakenly placed in water pipes. In some cases, water pipes can open and leak water. Such damage to water pipes is difficult to detect because it cannot be visually observed, especially after construction of floor boards and the like.

  Therefore, in order to solve such problems, conventionally, techniques for electrically detecting damage to water pipes have been proposed. For example, Japanese Patent Laid-Open No. 4-327088 discloses that at least the outer surface of a synthetic resin tube main body is coated with a conductive material. When a nail is driven into this synthetic resin tube, the conductive material, the nail, and the conductive material covering the inner surface of the synthetic resin tube main body or the water flowing inside the synthetic resin tube main body are electrically connected. Since it is connected, damage to the water pipe can be detected by electrically detecting this (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 4-327088

  However, in such a conventional water pipe flaw detection technique, the outer surface of the water pipe is covered with a metal material or a resin material. Therefore, when a nail is driven into the water pipe from an orthogonal direction, the opening force of the nail The metal material or the resin material is plastically deformed or torn due to (wide pore force or lateral pressure). Since the plastically deformed metal material or resin material has almost no binding force against the nail that is driven in, the gap formed between the nail and the nail cannot be closed, and the electrical contact with the nail is lost. Therefore, there is a problem that it is impossible to secure electrical connection between the metal material or resin material and the nail. In particular, when the water pipe is repeatedly subjected to various vibrations, the nail hole is further expanded, making it difficult to ensure conduction. Thus, although the conventional water pipe flaw detection technology has been theoretically constructed, it cannot actually ensure conduction, and is impractical.

  The present invention has been made in view of the above, and when a nail or the like is driven in, provides a pipe capable of ensuring the conduction between the nail and the conductive member and performing damage detection. The purpose is to do.

  In order to solve the above-described problems and achieve the object, the pipe according to claim 1 includes an insulating inner layer and a conductive or semiconductive outer layer covering at least a part of the surface of the inner layer. It is piping provided, Comprising: The said outer layer was comprised including the elastic body, It is characterized by the above-mentioned.

  The pipe according to claim 2 is the pipe according to claim 1, characterized in that the elastic body is a conductive rubber.

  The pipe according to claim 3 is the pipe according to claim 2, wherein the conductive rubber is any one of silicone rubber, ethylene propylene terpolymer, or urethane sponge.

  Further, the pipe according to claim 4 is the pipe according to claim 1, wherein the elastic body is a fiber structure having elasticity.

  The pipe according to claim 5 is the pipe according to claim 4, wherein the fiber structure is a carbon fiber felt.

  Further, the pipe according to claim 6 is the pipe according to any one of claims 1 to 5, wherein the outer layer, the elastic body, and a reinforcing body that reinforces the elastic body from the inside of the elastic body. It is characterized by comprising.

  Further, the pipe according to claim 7 is the pipe according to claim 2, wherein the outer layer comprises a silicone rubber as the elastic body and a reinforcing body that reinforces the elastic body from the inside of the elastic body. It is characterized by comprising silicone rubber having a tensile strength greater than that of the silicone rubber as the elastic body.

  The pipe according to claim 8 is the pipe according to claim 2, wherein the outer layer includes an ethylene propylene terpolymer as the elastic body and a reinforcing body that reinforces the elastic body from the inside of the elastic body. An ethylene propylene terpolymer having a tensile strength greater than that of the ethylene propylene terpolymer as the elastic body.

  The pipe according to claim 9 is the pipe according to claim 2, wherein the outer layer comprises a conductive rubber as the elastic body and a reinforcing body that reinforces the elastic body from the inside of the elastic body. It is characterized by comprising a cloth material.

  Moreover, the piping according to claim 10 is the piping according to any one of claims 1 to 9, wherein the inner layer is a crosslinked polyethylene simple substance composition, a composite composition of non-crosslinked polyethylene and crosslinked polyethylene, It contains vinyl chloride or polybutene.

  Further, the pipe according to claim 11 is the pipe according to any one of claims 1 to 10, wherein the conductive or semiconductive conductive means capable of contacting a fluid flowing inside the inner layer, Insulating means for insulating the conducting means and the outer layer from each other.

  According to the first aspect of the present invention, since the outer layer includes the elastic body, even when the outer layer is opened by a nail or the like, the outer layer is not deformed plastically, and the original shape is generated by the elastic force. The gap between the nail and the nail is almost closed, so that the continuity can be ensured. Accordingly, it is possible to provide a pipe to which the damage detection method can be practically applied.

  According to the second aspect of the present invention, the elastic body is formed of conductive rubber, so that even when the elastic body is opened by a nail or the like, the conductive rubber is not deformed plastically by its elastic force. The shape is restored and the gap with the nail is substantially closed, so that electrical conductivity can be ensured.

  According to the third aspect of the present invention, the restoring force can be further enhanced by forming the conductive rubber with a material having an excellent opening area ratio.

  Further, according to the present invention, the elastic body is formed of the fiber structure, so that the fiber structure is not deformed plastically by the elastic force even when it is opened by a nail or the like. The shape is restored and the gap with the nail is substantially closed, so that electrical conductivity can be ensured.

  Moreover, according to this invention of Claim 5, a restoring force can be heightened further by forming a fiber structure with the material excellent in the opening area rate especially.

  Moreover, according to this invention of Claim 6, the restoring force of an elastic body can be raised further by reinforcing an elastic body with a reinforcement body. Alternatively, it is possible to reduce the thickness of the elastic body and reduce the amount of the elastic body that is expensive to manufacture.

  According to the seventh aspect of the present invention, both conductivity and strength are obtained by reinforcing silicone rubber prioritizing conductivity with silicone rubber prioritizing tensile strength. Can do.

  Further, according to the present invention, the conductivity and strength of the ethylene propylene terpolymer with priority on conductivity are reinforced with the ethylene propylene terpolymer with priority on tensile strength. You can get both.

  Moreover, according to this invention of Claim 9, both electroconductivity and intensity | strength can be obtained by reinforcing the electroconductive conductive rubber with the cloth material with high intensity | strength.

  According to the invention of claim 10, the inner layer is formed by using a crosslinked polyethylene simple substance composition, a composite composition of non-crosslinked polyethylene and crosslinked polyethylene, vinyl chloride, or polybutene. Pipes suitable for water supply and hot water supply can be formed.

  Moreover, according to this invention of Claim 11, by providing a conduction | electrical_connection means and an insulation means, piping can be utilized for a flaw detection detection as it is.

  Embodiments of piping according to the present invention will be described below in detail with reference to the accompanying drawings. [I] First, the basic concept common to each embodiment was explained, then [II] the specific contents of each embodiment were explained, and [III] Finally, modifications to each embodiment were explained. To do. However, the present invention is not limited to each embodiment.

[I] Basic concept common to the embodiments First, the basic concept common to the embodiments will be described. The piping according to each embodiment is arranged under the floor of various buildings such as an apartment house, a detached house, or an accommodation facility, and is used as a water pipe for flowing tap water. is there. As a specific example, it can be used as a cross-linked polyethylene pipe for water supply as defined in JISK6787. However, the installation position and the purpose of use are not limited to this, and an arbitrary fluid can be made to flow at an arbitrary position.

  One of the features of this pipe is that the outer layer is formed of an elastic body in a pipe having an insulating inner layer and a conductive or semiconductive outer layer. In other words, the inner layer is covered with an elastic body having conductivity or semiconductivity, so that even when a nail or the like is accidentally struck, the outer layer tries to recover by elastic force, so there is a gap between the nail and the nail. The nail and the outer layer are in close contact with each other to maintain their electrical conductivity. The specific composition of such a conductive elastic body is arbitrary as long as it has elasticity, and examples thereof include conductive rubber and a fiber structure. Conventionally, conductive rubber has been used as a heating element for preventing dew condensation in electronic devices, a connector between electronic devices, a pressure-sensitive conductive device of a computer or a mobile phone, or an electromagnetic wave shield. These are usage methods that pay attention to the characteristics when the conductive rubber is energized or when a planar pressure is applied. We focused on the restoring force when the fiber structure was covered (when nails were placed). That is, when conductive rubber or fiber structure is opened by a nail or the like, it is restored to its original shape by its elastic force without plastic deformation, and the gap with the nail is substantially closed, which is useful for ensuring conductivity. It is. Furthermore, the present applicant has newly found a composition of conductive rubber and a fiber structure suitable for ensuring such conductivity.

[II] Specific Contents of Each Embodiment Next, specific contents of each embodiment according to the present invention will be described.

[Embodiment 1]
First, the first embodiment will be described. 1 is a cross-sectional view of a pipe according to the first embodiment, and FIG. 2 is a vertical cross-sectional view of the pipe of FIG. As shown in these drawings, the pipe 1 is configured to include an inner layer 2 and an outer layer 3, and a base 4, an insulating washer 5, and a metal ring 6 are attached to one end thereof.

(Inner layer 2)
Among these, the inner layer 2 is a cylinder that allows fluid to pass through the inside. The specific material of the inner layer 2 is arbitrary as long as it has insulating properties. For example, the entire inner layer 2 is formed of a crosslinked polyethylene single-component composition (single-layer tube), or the inner side of the inner layer 2 is crosslinked. It is formed as a composite composition formed of a polyethylene layer and an outer side formed of a non-crosslinked polyethylene layer (double-layer tube). As this cross-linked polyethylene, for example, water cross-linked polyethylene formed by cross-linking polyethylene having an active silane group in the molecule by contacting with water can be used. As such a crosslinked polyethylene, for example, trade name “LINKLON” manufactured by Mitsubishi Chemical Corporation can be used. In addition, a known piping material such as vinyl chloride or polybutene can be used for the inner layer 2.

(About outer layer 3)
The outer layer 3 covers substantially the entire outer surface of the inner layer 2 and is formed of a conductive or semiconductive elastic body. As such an elastic body, for example, conductive rubber and a fiber structure having elasticity can be cited. The details of each material will be described later, but in any material, conductivity sufficient to form a conductive state that can be detected during execution of the damage detection method described later (for example, resistivity 10 ⁻⁶ ohm · m or less). Or what has semiconductivity (for example, resistivity 10 < ^-6 > -10 < ⁷ > ohm * m or less) is used. The outer layer 3 is made of any material having elasticity. As the degree of the elastic force, when the outer layer 3 is opened by the nail 10, the elastic layer has a restoring force to restore the original shape by the elastic force without being plastically deformed. The thing which can ensure the electrical conductivity between the nail 10 and the outer layer 3 is calculated | required by substantially plugging.

(About the base 4 and the insulating washer 5)
The base 4 can contact a fluid flowing in the inner layer 2 and is made of metal and has conductivity, and corresponds to the conduction means in the claims. The base 4 includes an insertion port 4 a having a diameter smaller than that of the inner layer 2. The insertion port 4 a is inserted into the inner layer 2, and water W flowing inside the inner layer 2 can be introduced into the base 4. These insertion openings and the inner layer 2 (and the outer layer 3) are fastened by a metal ring 6. The insulating washer 5 is for insulating the base 4 and the outer layer 3 from each other, and corresponds to the insulating means in the claims. The insulating washer 5 is formed in an annular shape from an insulating member such as a synthetic resin, and is interposed between the outer layer 3 and the base 4 to insulate the outer layer 3 and the base 4 from each other.

(Damage detection method)
In such a configuration, the lead wire 11 is connected to the metal ring 6 (or the outer layer 3) and the base 4 and the lead wire 11 is connected to the continuity tester 12 to detect whether the pipe 1 is damaged. it can. That is, when the pipe 1 is not damaged, the continuity tester 12 does not detect continuity because the metal ring 6 (or the outer layer 3) and the base 4 are insulated from each other by the insulating washer 5. On the other hand, if the pipe 1 is damaged due to the nail 10 being accidentally hit or the like, the outer layer 3 (or the metal ring 6) passes through the nail 10 or the water W leaked from the inner layer 2 to the inner layer 2. It conducts with water W inside. At the same time, since the water W is also conducted with the base 4, as a result, the outer layer 3 (or the metal ring 6) and the base 4 become conductive with each other, and this state is detected by the conduction tester 12. Thus, based on the presence / absence of continuity detection by the continuity tester 12, the presence / absence of damage in the pipe 1 can be detected. In particular, since the outer layer 3 is formed of conductive rubber, even when the outer layer 3 is opened by the nail 10, the outer layer 3 is restored to its original shape by its elastic force without plastic deformation. As the gap is substantially closed, electrical conductivity can be ensured.

(Material of outer layer 3-conductive rubber)
Next, the material (composition) of the outer layer 3 will be described in more detail. As described above, the outer layer 3 can be formed of conductive rubber or a fiber structure. First, the conductive rubber will be described. In FIG. 3, the material of the conductive rubber applicable to the outer layer 3 is shown. As shown in FIG. 3, the conductive rubber includes (1) a rubber molded product, (2) a thermoplastic elastomer, (3) a sponge-like molded product made of these rubber molded product or thermoplastic elastomer, or (4 ) Urethane sponge (or urethane sponge rubber).

(About the material of the outer layer 3-conductive rubber-rubber molded product)
Among these, the rubber molded product is formed by mixing a rubber component, which is a raw material, with a compounding agent such as a crosslinking agent or a filler and crosslinking the mixture. Here, the rubber component as a raw material is roughly classified into natural rubber (NR) and synthetic rubber (abbreviations in parentheses are based on ASTM (American Society For Testing and Materials) standard, the same applies hereinafter). . Synthetic rubber includes styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), ethylene propylene terpolymer (EPDM), silicone rubber ( Q), urethane rubber (U), epichlorohydrin rubber (ECO), or acrylic rubber (ACM). A plurality of types of natural rubber or synthetic rubber may be mixed.

  In addition, as a part of the filler, a conductive filler for obtaining conductivity can be used. Examples of such conductive fillers include carbon-based conductive fillers, metal-based conductive fillers, and inorganic oxide conductive fillers. Carbon-based conductive fillers include carbon black (as specific examples, trade name “Ketjen Black EC” manufactured by Lion Corporation, trade name “Toka Black # 5500” manufactured by Tokai Carbon Co., Ltd., Electrochemical Industry Co., Ltd. Product name “acetylene black” manufactured by Showa Cabot Co., Ltd. or “Vulcan XC-72” manufactured by Showa Cabot Co., Ltd.), graphite (graphite) powder, carbon fiber (short carbon material, fiber powder. Specific examples include Osaka Gas The product name “Powder DonaCarbo” manufactured by Chemical Co., Ltd.) and carbon fine particles (specific examples include the product name “Mesocarbon Microbeads” manufactured by Osaka Gas Chemical Co., Ltd. In addition, as specific examples of metallic conductive fillers Are copper powder (product number Cu-At-100), copper alloy powder (product number Bro-Q), tin manufactured by Fukuda Metal Foil Powder Co., Ltd. The powder (product number Sn-At-250) and iron powder (product number Cu-Fe-Mn-At-100) can be mentioned, and specific examples of the inorganic oxide conductive filler include Otsuka Chemical Co., Ltd. Zinc oxide or titanium dioxide manufactured by Mitsubishi Materials Co., Ltd. can be used which is obtained by surface doping with a conductive tin compound, etc. Such various conductive fillers are other elastic materials in the first embodiment. It can also be applied to the body.

  As a method for producing a rubber molded product performed using such a material, a method similar to the conventional method can be basically used. That is, using a normal rubber kneading roll, a rubber component and another compounding agent are kneaded to make a compound (compounded rubber dough). Then, this compound is tubing with an extruder or sheeted with a calendar roll. Then, these are cross-linked with a predetermined jig or mold for about 60 minutes with a steam pressure vulcanizer at about 150 ° C. to make a cross-linked tube, or using a mold with an electric heat press at about 170 ° C. A rubber sheet is formed by crosslinking for about 15 to 20 minutes. The pipe 1 can be formed by measuring dimensions and volume resistance, finishing, and mounting and fixing to the outer periphery of the inner layer 2.

(Material of outer layer 3—conductive rubber—thermoplastic elastomer)
As the thermoplastic elastomer, a thermoplastic elastomer (TPE: Thermoplastic Elastomers), which is a raw material, is mixed with a conductive filler and injection molded, or a sheet molded product using a calender roll can be used. As this thermoplastic elastomer, a polystyrene, polyolefin, polyurethane, or polyester-based one having a low-temperature rigid temperature of about −50 to −30 ° C. and a softening temperature of about 65 ° C. to 150 ° C. should be used. Can do. In addition, as a conductive filler, the thing similar to what can be used for conductive rubber can be used.

(About the material of the outer layer 3-conductive rubber-sponge-like molded product)
Further, as the sponge-like molded product, a sponge-like product obtained by blending each of the above-described rubber molded product or thermoplastic elastomer with a foaming agent and heating and foaming it can be used.

(Material for outer layer 3-conductive rubber-urethane sponge)
Moreover, as urethane sponge (or urethane sponge rubber), a liquid rubber is used as a rubber component (starting material), and a cross-linking agent containing a conductive filler and a foaming component is mixed. And a sponge-like molded article can be used by heating and foaming this, or taking in the air bubbled by the mechanical means as a microbubble at the time of a crosslinking reaction.

(About the material of the outer layer 3-fiber structure)
Next, the material of the fiber structure will be described in more detail. The fiber structure in the first embodiment is an aggregate (or aggregate, cotton collection) of fiber materials, and is mainly composed of conductive or semiconductive carbon fibers, Includes what are called mats and felts. Such a fiber structure has an irregular curling property possessed by carbon fibers, three-dimensionalization (three-dimensionalization) by needle punching, etc. It is characterized by high resilience. The pipe 1 can be formed by forming such a fiber structure into a sheet shape and mounting and fixing it on the outer periphery of the inner layer 2.

(About test results)
Next, various test results conducted by the applicant will be described. Here, after explaining the results of the rebound resilience test and the continuity test conducted mainly to confirm the effect of the first embodiment, the material of the elastic body suitable mainly for the purpose of the first embodiment is described. The result of the opening test performed for specifying will be described.

(Test result-impact resilience test)
First, the results of the impact resilience test will be described. It is known that the elasticity includes rubber elasticity (entropy elasticity) and energy elasticity. Rubber elasticity (entropic elasticity) is elasticity that can be stored as energy for the elastic body to sufficiently absorb and return to an external force when an external force is applied to the elastic body. On the other hand, energy elasticity is elasticity in which, when an external force is applied to the elastic body, this energy is not stored in the elastic body, and the energy is changed due to plastic deformation or destruction of the elastic body. Here, since the first embodiment is to restore the gap with the nail 10 using the elastic force of the outer layer 3, it is preferable that the rubber elasticity is large. The magnitude of this rubber elasticity was confirmed as follows from the results of the impact resilience test.

  FIG. 4 shows the result of the impact resilience test (note that the manufacturer name and product number of the product used as the sample are shown in the figure. The same applies to each figure showing the test results). Here, according to a test method based on JIS-K6255, two types of representative materials used in conventional flaw detection techniques (resin material PET (Polyethylene Terephthalate) and metal material aluminum), Using two types of materials (ethylene propylene terpolymer and silicone rubber) exemplified in the first embodiment as samples, tests were conducted at two test temperatures of 20 ° C. and 50 ° C. As a result, the resilience of the material exemplified in the first embodiment is 51 to 58%, and the resilience increases as the temperature rises, and this represents the entropy elasticity itself. The conventional material has a rebound resilience of 18-49%, which is remarkably lowered with a rise in temperature, and shows just energy resilience, which correlates with extremely low opening restoring force. From these, it was confirmed that according to the first embodiment, high rubber elasticity can be secured.

(Test result-continuity test)
Next, the results of the continuity test will be described. FIG. 5 is a side view showing the test state when nailing, and FIG. 6 is a plan view showing the test state when pulling out the nail. As shown in the figure, a conductive rubber 7 as a sample is placed on the upper surface of a wooden base 20 having a sufficient thickness, and a metallic nail (or screw) 10 is vertically applied to the conductive rubber 7 from above. Was placed at a predetermined depth. In this state, continuity between the end of the conductive rubber and the nail (or screw) 10 was measured with a continuity tester (not shown).

  FIG. 7 shows the results of the continuity test. Here, a typical material (aluminum which is a metal material) used in conventional flaw detection technology and a material (silicone rubber) exemplified in the first embodiment are used as samples, and a nail is driven. The test was performed 10 times each when the screw was placed. As a result, the conductivity of the conventional metal material was 70 to 80%, whereas the conductivity of the silicone rubber was 100%, and it was confirmed that high conductivity can be secured according to the first embodiment. It was done.

(Test result-opening test)
Finally, the results of the opening test will be described. As shown in FIGS. 5 and 6, a nail 10 having a predetermined outer diameter is placed on the conductive rubber 7 from above, and then the nail 10 is pulled out from the conductive rubber 7. Then, when the nail 10 is placed in the conductive rubber 7, a hole having the same diameter as the outer diameter D1 of the nail 10 is formed. However, by pulling out the nail 10, the conductive rubber is restored and the hole is formed. The diameter is reduced to D2. In this test, the ratio (opening area ratio = (S1 / S2) × 100 (%)) of the flat area S1 of the hole having the diameter D2 after the reduction and the cross-sectional area S2 of the nail 10 is calculated. The resilience was determined. That is, the smaller the opening area ratio, the higher the restoring force of the sample.

  FIG. 8 shows the results of the opening test. Here, two types of representative materials used in the conventional flaw detection technology (aluminum which is a metal material and a conductive plastic which is a resin material) and a plurality of materials exemplified in the first embodiment The test was conducted five times each for the case where the diameter of the nail 10 was 2.5 mm and 5.0 mm. As a result, the average opening area ratio of the conventional material was 49.62 to 104.46% (the opening area ratio of 100% or more is caused by the opening of the nail 10 and the hole is torn. The average opening area ratio of the material exemplified in the first embodiment is 0.00 to 48.12%, which is high according to the first embodiment. It was confirmed that resilience could be secured.

  In particular, in the case of a nail having a diameter of 2.5 mm, which is usually used for construction of flooring, the average opening area ratio of the conductive rubber and the fiber structure is 9.49% at the maximum, which is remarkable compared to conventional materials It was confirmed that it has a strong resilience. Therefore, by forming the outer layer 3 with each material exemplified in the first embodiment, the gap between the nail 10 can be substantially closed with a high restoring force, and the conductivity between the nail 10 is further increased. It has been found that it can be surely secured.

[Embodiment 2]
Next, the specific content of Embodiment 2 which concerns on this invention is demonstrated. In the second embodiment, the outer layer 3 is formed in a two-layer structure of an elastic body (hereinafter referred to as an outer layer surface material) and a reinforcing body (hereinafter referred to as an outer layer inner surface material). The configuration of the second embodiment is substantially the same as the configuration of the first embodiment except where otherwise specified, and the same configuration as that of the first embodiment is used in the first embodiment. The same reference numerals are attached as necessary, and the description thereof is omitted.

  Here, the outer layer 3 having both conductivity and strength is formed, for example, by reinforcing rubber that prioritizes conductivity with rubber or cloth material that is inferior in conductivity but high in strength. The combination of such materials is arbitrary, but in the following, when (1) the outer layer surface material and the outer layer inner surface material are formed of two types of silicone rubber having different tensile strengths, etc., (2) the outer layer surface When the material and outer layer inner material are made of ethylene propylene terpolymers with different tensile strength, etc., (3) When the outer layer surface material is made of conductive rubber and the outer layer inner surface material is made of cloth material These will be described sequentially.

(In the case of two types of silicone rubber)
First, the case where the outer layer surface material and the outer layer inner surface material are formed of two types of silicone rubbers having different tensile strengths will be described. Here, for example, the silicone rubber constituting the outer layer surface material has a thickness of about 1 mm and the silicone rubber constituting the outer layer inner surface material has a thickness of about 0.5 mm. An outer layer 3 of 1.5 mm is formed. The silicone rubber constituting the outer layer surface material has a composition that prioritizes conductivity, for example, product number KE3601SB-U (hardness: 62 durometer A, tensile strength 7.0 MPa) manufactured by Shin-Etsu Chemical Co., Ltd. Is used. On the other hand, as the silicone rubber constituting the inner surface material of the outer layer, a material giving priority to tensile strength over conductivity, for example, product number SEP855B-U (hardness: 63 durometer A, tensile strength, manufactured by Shin-Etsu Chemical Co., Ltd.) 13.0 MPa), or by increasing the cross-linking agent by several parts by weight, or by adding about several parts by weight of the co-cross-linking agent to improve hardness and tensile strength.

  The integral cross-linking molding method of these two types of silicone rubber will be described. First, a silicone rubber compound (uncrosslinked compounded rubber) for the outer layer surface material and a silicone rubber compound for the outer layer inner surface material are each sheeted with a calender roll and cut into a predetermined size. Then, the outer layer surface material and the outer layer inner surface material are directly overlapped with each other, set in the cavity of the compression mold, and the mold is put into an electric heating press and heated and crosslinked at a predetermined pressure and a predetermined temperature. . Then, the cross-linked sheet (integrated cross-linked molded sheet) taken out from the mold is cut into a predetermined size, and the outer layer 3 is completed.

  The advantages of such a method are as follows. In other words, conductive silicone rubber is designed with priority given to the stable development of its conductivity, so its rubber strength is of a very weak class, and the opening force during nailing There is a possibility of tearing. In order to prevent this, it is conceivable to design silicone rubber by giving priority to improving the rubber strength, but in this case, the conductivity is not stably developed and the conduction necessary for damage detection is not achieved. The possibility of not being obtained arises. For this reason, as mentioned above, like SEP rubber (EPDM modified with silicone rubber), a compound whose composition is close to that of silicone rubber and has high strength, and a compound with improved cross-linking density, etc. By simultaneously and integrally forming the outer layer surface material prioritizing conductivity, the advantages of both the conductivity by the outer layer surface material and the rubber strength by the outer layer inner surface material can be obtained, which is very effective. In addition, the silicone rubber used as the reinforcing body can improve the tensile strength per unit volume by adjusting the blending of the crosslinking agent and the co-crosslinking agent as described above, but the same per unit volume. The tensile strength of the entire silicone rubber may be improved by increasing the thickness of the tensile strength silicone rubber. For example, the silicone rubber of the reinforcing body may have a thickness of 2 mm or more. The thickness of such a silicone rubber can be determined in consideration of its moldability, wrapping property, or cost (in addition, the point that the thickness may be increased in this way is ethylene as a reinforcing body to be described later) The same applies to propylene terpolymers).

(In the case of two ethylene propylene terpolymers)
Next, a case where the outer layer surface material and the outer layer inner surface material are formed of ethylene propylene terpolymers having different tensile strengths will be described. However, structures and methods that are not particularly explained are the same as in the case of two types of silicone rubber. As the ethylene propylene terpolymer constituting the outer layer surface material, one giving priority to conductivity (for example, hardness: about 60 to 63 durometer A, tensile strength of about 10.0 MPa) is used. On the other hand, as the ethylene propylene terpolymer constituting the outer layer inner surface material, the tensile strength can be increased by adding about several tens parts by weight of filler or about several parts by weight of a crosslinking agent or a co-crosslinking agent to the outer layer surface material. An improved material (for example, hardness: about 70 durometer A and tensile strength of about 18.0 MPa) is used. Then, these two types of silicone rubbers are integrally cross-linked in the same manner as in the case of the two types of silicone rubbers to form the outer layer 3.

(For conductive rubber and cloth materials)
Finally, a case where the outer layer surface material is formed of conductive rubber and the outer layer inner surface material is formed of a cloth material will be described. However, structures and methods that are not particularly explained are the same as in the case of two types of silicone rubber. As the conductive rubber for the outer surface material, for example, acrylonitrile butadiene rubber (NBR) is used. Moreover, as a cloth material of the outer layer inner surface material, for example, a very small woven cloth (for example, 66 nylon woven cloth) that is thin and has a longitudinal elongation and a lateral elongation of 10 to 20% or less is used.

  A method for joining the conductive rubber and the cloth material will be described. First, a so-called co-glue (rubber paste) is prepared by dissolving NBR compound (uncrosslinked rubber) in advance to about several tens of percent in a xylene-based mixed solvent. This rubber paste is applied to a nylon woven fabric several times using a brush and dried. Alternatively, a commercially available NBR type cross-linking adhesive is applied to a nylon woven fabric and dried. And this nylon woven fabric is cut | judged, this is piled up with the NBR compound seated with the calender roll, and it sets to a compression metal mold | die. Thereafter, as in the case of the two types of silicone rubbers, a rubber sheet reinforced with a nylon woven fabric is completed by simultaneous integral cross-linking molding.

[III] Modifications to Embodiments Although the embodiments of the present invention have been described above, the specific configuration and means of the present invention are within the scope of the technical idea of each invention described in the claims. Can be arbitrarily modified and improved. Hereinafter, such a modification will be described.

(About problems to be solved and effects of the invention)
First, the problems to be solved by the invention and the effects of the invention are not limited to the above-described contents, and the present invention solves the problems not described above or has the effects not described above. There are also cases where only some of the described problems are solved or only some of the described effects are achieved. For example, even when the flaw detection cannot be performed completely, the problem of the present application is solved as long as the realization rate is increased as much as possible as compared with the conventional piping.

(Regarding the formation of outer layer)
Moreover, the outer layer 3 may be formed only on a part of the outer surface in addition to being formed on the entire outer surface of the inner layer 2. In FIG. 9, the example which formed the outer layer 3 only in a part of outer surface of the inner layer 2 is shown as a perspective view (however, the nozzle | cap | die 4 is abbreviate | omitted). As shown in FIG. 9, for example, when it is known in advance which of the inner layers 2 is arranged toward the floor material, the outer surface corresponding to the floor material (for example, the upper surface side of the inner layer 2) The outer layer 3 may be formed only on the outer surface arranged so as to come to the center, and the nail 10 placed on the floor material may be inserted into the outer layer 3. Although not shown, the outer layer 3 may be formed only on a part of the inner layer 2 in the longitudinal direction. In these cases, even if the material cost and molding cost of the outer layer 3 are high, the cost can be reduced as much as possible, and the cost of the entire pipe can be reduced.

(About materials of each part)
In addition, the materials, compositions, dimensions, shapes, molding conditions, and the like of each part described above are examples, and can be arbitrarily changed. For example, the base 4 may be made of a semiconductive material instead of a metal.

  The piping according to the present invention is used as piping for hot water supply for water supply, and is a piping to which a damage method using conductivity can be applied with high feasibility.

It is a cross-sectional view of piping which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view of piping of FIG. It is a figure which shows the material of the conductive rubber applicable to an outer layer. It is a figure which shows the result of a rebound resilience test. It is a side view which shows the test state at the time of nailing. It is a top view which shows the test state at the time of nail extraction. It is a figure which shows the result of a continuity test. It is a top view which shows the result of an opening test. It is a perspective view which shows the example which formed the outer layer only in a part of outer surface of the inner layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piping 2 Inner layer 3 Outer layer 4 Base 4a Insertion port 5 Insulating washer 6 Metal ring 7 Conductive rubber 10 Nail 11 Lead wire 12 Conduction tester 20 Wooden stand

Claims (11)

A pipe comprising an insulating inner layer and a conductive or semiconductive outer layer covering at least a part of the surface of the inner layer,
The outer layer includes an elastic body;
Piping characterized by The elastic body is a conductive rubber;
The piping according to claim 1. The conductive rubber is one of silicone rubber, ethylene propylene terpolymer, or urethane sponge,
The piping according to claim 2. The elastic body is a fiber structure having elasticity;
The piping according to claim 1. The fiber structure is a carbon fiber felt;
The piping according to claim 4. The outer layer is composed of the elastic body and a reinforcing body that reinforces the elastic body from the inside of the elastic body,
The piping according to any one of claims 1 to 5, wherein: The outer layer constitutes a silicone rubber as the elastic body and a reinforcing body that reinforces the elastic body from the inside of the elastic body, and has a higher tensile strength than the silicone rubber as the elastic body Made up of rubber,
The piping according to claim 2. The outer layer constitutes an ethylene propylene terpolymer as the elastic body and a reinforcing body that reinforces the elastic body from the inside of the elastic body, and has a tensile force larger than that of the ethylene propylene terpolymer as the elastic body. That composed of a strong ethylene propylene terpolymer,
The piping according to claim 2. The outer layer is composed of conductive rubber as the elastic body, and a cloth material constituting a reinforcing body that reinforces the elastic body from the inside of the elastic body,
The piping according to claim 2. The inner layer contains a crosslinked polyethylene simple substance composition, a composite composition of non-crosslinked polyethylene and crosslinked polyethylene, vinyl chloride, or polybutene,
The piping according to any one of claims 1 to 9, wherein: Conductive or semiconductive conducting means capable of contacting fluid flowing in the inner layer;
Insulating means for insulating the conducting means and the outer layer from each other;
The pipe according to any one of claims 1 to 10, wherein the pipe is provided.

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