JP6972942B2 - Pressure sensor - Google Patents

Description

The present invention relates to a pressure sensitive sensor.

For example, a vehicle is equipped with an automatic opening / closing device that electrically moves a door panel. The automatic switchgear is equipped with a pressure-sensitive sensor to detect when a foreign object or a human body is pinched or touched at the opening / closing part between the peripheral edge of the vehicle entrance / exit and the door panel (the automatic opening / closing device). For example, see Patent Document 1).

The pressure-sensitive sensor generally faces a long hollow insulator in which a hollow portion is continuously formed in the longitudinal direction and a hollow insulator that is separated from each other so as to be in contact with each other when the hollow insulator is elastically deformed. It is configured to include a plurality of electrode wires to be arranged. The electrode wire has a conductive coating formed from a conductive resin composition on the outer periphery of the conductor. In the pressure-sensitive sensor, when the hollow insulator is elastically deformed in response to the external pressure due to contact with the foreign matter, the electrode wires in the hollow portion come into contact with each other and the resistance value changes, so that the foreign matter comes into contact. Is detected.

Since the conductive coating of hollow insulators and electrode wires requires flexibility and resilience from elastic deformation from the viewpoint of obtaining the desired sensitivity in a pressure-sensitive sensor, a rubber composition is generally used as a material for forming them. Is used. The rubber composition is based on a rubber component such as an ethylene-propylene-diene copolymer or silicone rubber, and a conductivity-imparting agent such as carbon black is blended in the case of imparting conductivity.

When the hollow insulator or the conductive coating is formed of the rubber composition, a cross-linking treatment is performed after molding in order to obtain a desired elastic modulus. As the cross-linking treatment, there is a method of cross-linking with hot air, a hot press, high pressure steam, or the like. However, if these cross-linking treatments are performed in a separate process from the molding of the rubber composition, the number of steps increases, and even if the cross-linking treatment is performed on the same line as the molding, the cross-linking treatment takes time, which may increase the manufacturing cost. There is.

Therefore, instead of the rubber component, it is considered to use an elastomer component that does not require a cross-linking treatment after molding. For example, styrene-based thermoplastic elastomers have been studied (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-158336 Japanese Unexamined Patent Publication No. 2012-119309

By the way, an outer layer as a protective member is provided on the outer periphery of the hollow insulator. This outer layer is required to have not only properties as a protective member but also flexibility and resilience from elastic deformation as in the case of hollow insulators and conductive coatings. Therefore, as a material for forming the outer layer, thermoplastic polyurethane having excellent mechanical properties has been studied.

However, when the outer layer is formed from the composition containing the thermoplastic polyurethane, the adhesiveness to the hollow insulator formed from the composition containing the styrene-based thermoplastic elastomer may not be sufficiently ensured. In a pressure-sensitive sensor, the terminal may be sealed with resin for the purpose of improving the waterproofness inside the sensor, but if the adhesiveness between the hollow insulator and the outer layer is insufficient, the injection-molded resin will be used. By invading the interface, poor appearance and poor dimensions occur.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a pressure-sensitive sensor having excellent adhesion between a hollow insulator and an outer layer.

According to one aspect of the invention
An elastically deformable long hollow insulator in which hollow portions are continuously formed in the longitudinal direction,
A conductive coating is provided on the outer periphery of the conductor, which is provided along the inner peripheral surface of the hollow portion in the longitudinal direction and is arranged so as to be separated from each other so as to come into contact with each other when bent due to elastic deformation of the hollow insulator. Multiple electrode wires provided and
With an outer layer, which is formed to cover the outer circumference of the hollow insulator,
The hollow insulator is formed from the insulating composition (A) containing the styrene-based thermoplastic elastomer (a1).
A pressure sensitive sensor is provided in which the outer layer is formed of an insulating composition (C) containing a thermoplastic polyurethane (c1) and an acid-modified polymer (c2) modified with an unsaturated carboxylic acid or a derivative thereof.

According to the present invention, a pressure-sensitive sensor having excellent adhesion between the hollow insulator and the outer layer can be obtained.

(A) is a perspective view showing a schematic configuration of a pressure-sensitive sensor according to an embodiment of the present invention, and (b) is a cross-sectional view perpendicular to the longitudinal direction of the pressure-sensitive sensor. It is sectional drawing which shows the state which the pressure sensitive sensor was deformed by the external pressure. It is a schematic diagram explaining the test method which evaluates the adhesiveness between an electrode wire and a hollow insulator in a pressure sensitive sensor, and compression resistance in a high temperature environment in an Example. It is a schematic diagram when the terminal of a pressure sensitive sensor is sealed with a mold resin.

<One Embodiment of the present invention>
Hereinafter, the pressure sensor according to the embodiment of the present invention will be described with reference to the drawings. 1A is a perspective view showing a schematic configuration of a pressure-sensitive sensor according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view perpendicular to the longitudinal direction of the pressure-sensitive sensor. FIG. 2 is a cross-sectional view showing a state in which the pressure sensitive sensor is deformed by external pressure. The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[Rough configuration of pressure sensor]
As shown in FIGS. 1 (a) and 1 (b), the pressure-sensitive sensor 10 of the present embodiment includes an elastically deformable long hollow insulator 14 in which the hollow portion 15 is continuously formed in the longitudinal direction. On the outer periphery of the conductor 11, which is provided along the inner peripheral surface of the hollow portion 15 in the longitudinal direction and is spaced apart from each other so as to come into contact with each other when bent due to the elastic deformation of the hollow insulator 14. It is a long cable-like object including a plurality of electrode wires 13 provided with a conductive coating 12 and an outer layer 16 formed so as to cover the outer periphery of the hollow insulator 14.

The hollow insulator 14 is formed of the insulating composition (A) described later, and the hollow portion 15 is continuously formed in the longitudinal direction to form a substantially cylindrical shape, whereby the pressure-sensitive sensor 10 receives external pressure. It is sometimes configured to be elastically deformable.

The hollow insulator 14 may have a hollow portion 15, and its shape and thickness are not particularly limited. The hollow portion 15 may have a size that can accommodate a plurality of electrode wires 13 so as not to come into contact with each other, and can be appropriately changed according to the number of electrode wires 13.

A pair of electrode wires 13 are arranged on the inner peripheral surface of the hollow portion 15 of the hollow insulator 14 so as to be held by the hollow insulator 14. The pair of electrode wires 13 are arranged to face each other at a distance from each other so as not to come into contact with each other in the hollow portion 15. Further, in the present embodiment, as shown in FIG. 1A, the pair of electrode wires 13 are spirally wound along the inner peripheral surface of the hollow portion 15 in the longitudinal direction in the pressure sensitive sensor 10. They are arranged so as to face each other at any position in the longitudinal direction.

As shown in FIG. 1 (b), the electrode wire 13 includes a conductor 11 and a conductive coating 12 formed from the conductive composition (B) described later.

As the conductor 11, a commonly used metal wire, for example, a copper wire, an annealed copper wire, a copper alloy wire, an aluminum wire, a gold wire, a silver wire, or the like can be used. Further, in order to improve the heat resistance, a metal wire having a metal plating such as tin, nickel, silver and gold on the outer periphery thereof may be used. Further, a collective twisted conductor obtained by twisting metal wires can also be used. The outer diameter of the conductor 11 is not particularly limited, and may be appropriately changed according to the electrical characteristics required for the electrode wire 13.

A conductive coating 12 is provided on the outer periphery of the conductor 11. The conductive coating 12 is formed of the conductive composition (B) described later, and is made conductive when the electrode wires 13 are bent and the electrode wires 13 come into contact with each other due to the deformation of the hollow insulator 14 due to the external pressure. The thickness of the conductive coating 12 may be appropriately changed according to the conductivity and flexibility required for the electrode wire 13.

An outer layer 16 is provided on the outer periphery of the hollow insulator 14. The outer layer 16 is formed of the insulating composition (C) described later, and covers and protects the hollow insulator 14. The thickness of the outer layer 16 may be such that the hollow insulator 14 is covered and protected while maintaining flexibility.

In the pressure sensor 10, for example, two electrode wires 13 drawn from one terminal are connected via a resistor, and a feeding unit (not shown) is connected to the two electrode wires 13 drawn from the other terminal. It is connected and configured to supply current to the electrode wire 13. Then, as shown in FIG. 1 (b), when no external pressure is applied to the pressure sensitive sensor 10, the current supplied from the feeding unit to one electrode wire 13 passes through the resistor to the other electrode wire 13. Flow to. On the other hand, as shown in FIG. 2, when an external pressure is applied to the pressure-sensitive sensor 10, the hollow insulator 14 at the location where the external pressure is applied is elastically deformed, and the electrode wire in the hollow portion 15 is deformed due to the deformation. When the 13 is bent, the electrode wires 13 come into contact with each other, and a current flows from the contact portion. As a result, the resistance value fluctuates, and if the feeding unit supplies a current at a constant voltage, the current value changes. Then, by detecting the change in the current value, it is detected that the external pressure is applied to the pressure sensitive sensor 10.

[Material for forming each member]
Subsequently, each forming material of the hollow insulator 14 constituting the pressure-sensitive sensor 10, the conductive coating 12 of the electrode wire 13, and the outer layer 16 will be described.

(Material for forming hollow insulator)
As described above, in this embodiment, in order to omit the cross-linking treatment of the hollow insulator 14, the hollow insulator 14 is replaced with the rubber composition that requires the cross-linking treatment, and an elastomer composition that does not require the cross-linking treatment is used. To form. As this elastomer composition, an insulating composition (A) containing a styrene-based thermoplastic elastomer (a1) is used from the viewpoints of mechanical properties, heat resistance, flexibility, and resilience from elastic deformation (compression resistance). ..

The styrene-based thermoplastic elastoma (a1) (hereinafter, also simply referred to as the component (a1)) includes a polymer block made of a styrene-based monomer (for example, polystyrene) as a hard segment and a polymer block made of an olefin as a soft segment. , A block copolymer or a random copolymer having. Specifically, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene-butadiene-styrene block copolymer (SIBS), and hydrogen thereof. Styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), etc. added Can be used. These may be used alone or in combination of two or more.

The heat resistance of the styrene-based thermoplastic elastoma (a1) increases as the number of unsaturated bonds in the molecular chain decreases. Therefore, from the viewpoint of improving the heat resistance of the hollow insulator 14, double bonds to the molecular chain are obtained by hydrogenation. Is preferable, and specifically, SEBS, SEPS, SEEPS and the like are preferable.

The styrene-based thermoplastic elastomer (a1) is used even when the hollow insulator 14 is repeatedly deformed in a high-temperature environment from the viewpoint of enhancing the operability (high-temperature operability) of the pressure-sensitive sensor 10 in a high-temperature environment. It is preferable that the original shape can be restored, and the compression set at 70 ° C. is preferably 30% or less. If the compression set becomes large, when the hollow insulator 14 is repeatedly deformed, the electrode wires 13 remain in contact with each other without being restored, and the pressure sensor 10 may not operate normally. By setting the content to 30% or less, the high temperature operability of the pressure sensor 10 can be maintained high. The compression set at 70 ° C. here is measured in accordance with JIS K6262.

The styrene content and molecular weight of the styrene-based thermoplastic elastomer (a1) are not particularly limited.

Further, the insulating composition (A) may contain a rubber component, a crystalline resin, or the like in addition to the styrene-based thermoplastic elastomer (a1).

Further, the insulating composition (A) is a processing aid, an oil, a flame retardant, a flame retardant, a cross-linking aid, an ultraviolet absorber, an antioxidant, a copper damage inhibitor, a lubricant, a filler, as needed. Other additives such as compatibilizers, stabilizers and colorants may be included.

(Material for forming conductive coating)
The conductive coating 12 does not come off from the hollow insulator 14 even if the process of deforming the hollow insulator 14 and restoring it to the original state is repeated in order to make the pressure sensor 10 function for a long period of time. Adhesiveness is required. In the present embodiment, in order to obtain the desired adhesiveness, the conductive coating 12 is formed by using the same elastomer component as the hollow insulator 14, and a conductivity-imparting agent is blended to impart predetermined conductivity. Is preferable. That is, the conductive coating 12 is preferably formed from the conductive composition (B) containing the styrene-based thermoplastic elastomer (b1) and the conductive agent (b2).

As the styrene-based thermoplastic elastomer (b1) (hereinafter, also simply referred to as the component (b1)) that forms the conductive coating 12, the same styrene-based thermoplastic elastomer (a1) that forms the hollow insulator 14 is used. be able to.

The conductivity-imparting agent (b1) imparts conductivity to the styrene-based thermoplastic elastomer (b1). The conductivity-imparting agent (b1) is not particularly limited, and for example, carbon black can be used. As the carbon black, furnace black, ketjen black, acetylene black, channel black, thermal black, lamp black and the like can be used. These may be used alone or in combination of two or more. Among carbon blacks, Ketjen black is preferable. According to Ketjen Black, excellent conductivity can be obtained with a small amount of compounding, so that the amount of compounding to the conductive coating 12 can be reduced to maintain high flexibility. The particle size is not particularly limited.

The blending amount of the conductivity-imparting agent (b1) may be appropriately changed according to the conductivity required for the conductive coating 12, but is 10 parts by mass to 100 parts by mass with respect to 100 parts by mass of the styrene-based thermoplastic elastomer (b1). It is preferably a part. By setting the amount to 10 parts by mass or more, the desired conductivity can be obtained in the conductive coating 12. By setting the content to 100 parts by mass or less, it is possible to prevent the conductive composition (B) from becoming hard due to the blending of the conductivity-imparting agent (b1), and the conductive coating 12 as well as the processability of the conductive composition (B). Can maintain high flexibility and wear resistance.

As with the insulating composition (A), the conductive composition (B) may contain a rubber component other than the styrene-based thermoplastic elastomer (b1), a crystalline resin, or the like, and may contain the above-mentioned other additives. It may be included.

(Material for forming the outer layer)
The outer layer 16 is required to have mechanical properties that can protect the hollow insulator 14, flexibility, and high adhesiveness to the hollow insulator 14. In the present embodiment, the thermoplastic polyurethane (c1) (hereinafter, also simply referred to as the (c1) component) is used from the viewpoint of mechanical properties and flexibility, and the (c1) component is a styrene-based thermoplastic that forms the hollow insulator 14. The affinity with the elastomer (b1) is low, and sufficient adhesion with the hollow insulator 14 cannot be obtained. Therefore, in the present embodiment, the component (c1) is blended with an acid-modified polymer (c2) modified with an unsaturated carboxylic acid or a derivative thereof (hereinafter, also simply referred to as a component (c2)) to improve the adhesiveness. ing.

The thermoplastic polyurethane (c1) is obtained by reacting a diol component, a diisocyanate component, and a chain extender, if necessary, and particularly contributes to the mechanical properties and flexibility of the outer layer 16. As the component (c1), polyester-based polyurethane (adipate-based, caprolactone-based, polycarbonate-based, etc.) and polyether-based polyurethane can be used. From the viewpoint of moisture resistance and heat resistance, polyether polyurethane is preferable.

Examples of the diol component constituting the thermoplastic polyurethane (c1) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-. 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10- An aliphatic diol such as decanediol; an alicyclic diol such as cyclohexanedimethanol and cyclohexanediol can be used. These may be used alone or in combination of two or more.

Examples of the diisocyanate component constituting the thermoplastic polyurethane (c1) include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, cyclohexylmethane diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene. An aliphatic or alicyclic diisocyanate such as diisocyanate, isopropyridenebis (4-cyclohexamethylene), methylcyclohexane diisocyanate, isophorone diisocyanate, 2,4- or 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, Fragrances such as 3-methyldiphenylmethane-4,4'-diisocyanate, m- or p-phenylenediocyanate, chlorophenylene-2,4-diisocyanate, naphthalene-1,5-diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, etc. Diisocyanate or the like can be used. These may be used alone or in combination of two or more.

The acid-modified polymer (c2) is a polymer modified with an unsaturated carboxylic acid or a derivative thereof, and enhances the adhesiveness of the outer layer 16 to the hollow insulator 14.

Examples of the polymer constituting the acid-modified polymer (c2) include polypropylene, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, ethylene-butene-1 copolymer, and ethylene-hexene-1. Polymers, ethylene-octene-1 copolymers, polybutene, poly-4-methyl-pentene-1, ethylene-butene-hexene ternary copolymers, ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers , Ethylene-ethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, and crystalline resins such as ethylene-glycidyl methacrylate copolymers, ethylene-propylene-diene copolymers, ethylene-propylene copolymers, ethylene-butene. Use rubbers such as -1-diene copolymers, ethylene-octene-1-diene copolymers, acrylonitrile butadiene rubbers, and acrylic rubbers, and thermoplastic elastomas such as polyolefins, styrenes, polyesters, and polyamides. be able to.
As the unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like can be used, and as the derivative of the unsaturated carboxylic acid, there are metal salts, amides, esters, anhydrides and the like of the unsaturated carboxylic acid. Of these, maleic anhydride is preferable.

As the acid-modified polymer (c2), the compression set at 70 ° C. is 70 among the above components from the viewpoint of reducing the compression set of the outer layer 16 at high temperature and maintaining the high temperature operability of the pressure sensitive sensor 10. % Or less is preferable. According to such a component (c2), when the outer layer 16 is formed by mixing with the thermoplastic polyurethane (c1) having a relatively small compression set, the compression set can be reduced to 60% or less. Since the volume per unit length of the pressure-sensitive sensor 10 (so-called amount of grain) of the outer layer 16 is smaller than that of the hollow insulator 14, the compression set may be larger than that of the hollow insulator 14, but 60 By setting the content to% or less, the high temperature operability of the pressure sensor 10 can be maintained higher. The crystallinity and molecular weight of the acid-modified polymer (c2) may be in the range where the compression set is 70% or less.

The content of the thermoplastic polyurethane (c1) and the acid-modified polymer (c2) in the insulating composition (C) forming the outer layer 16 is not particularly limited, but the component (c1) is 30 parts by mass to 99 parts by mass. It is preferable that the component (c2) is contained in an amount of 1 part by mass to 70 parts by mass in a total of 100 parts by mass. Adhesion to the hollow insulating layer can be ensured by setting the blending amount of the component (c2) to 1 part by mass or more, while the mechanical properties and flexibility inherent in the component (c1) are set to 70 parts by mass or less. The sex can be maintained high. From the viewpoint of obtaining a good balance of adhesiveness, mechanical properties and flexibility at a high level, it is preferable that the component (c1) is 40 parts by mass to 95 parts by mass and the component (c2) is 5 parts by mass to 60 parts by mass.

The insulating composition (C) may contain the above-mentioned other additives as in the insulating composition (A) and the conductive composition (B).

[Manufacturing method of pressure sensor]
Subsequently, a method of manufacturing the pressure sensitive sensor 10 will be described.

First, the electrode wire 13 provided with the conductive coating 12 on the outer periphery of the conductor 11 is prepared. The electrode wire 13 is produced, for example, by extruding a conductive composition (B) containing a styrene-based thermoplastic elastomer (b1) and a conductive agent (b2) onto the outer periphery of the conductor 11 to form a conductive coating 12.

Subsequently, around one long spacer, two electrode wires 13 and four long spacers are arranged so as to be separated from each other so that the electrode wires 13 do not come into contact with each other. Are twisted together to form a core. In the core, the two electrode wires 13 are spirally opposed to each other along the longitudinal direction of the spacer.

Subsequently, the insulating composition (A) containing the styrene-based thermoplastic elastomer (a1) is extruded on the outer periphery of the core to form a substantially cylindrical insulator covering the core. Further, the insulating composition (C) containing the thermoplastic polyurethane (c1) and the acid-modified polymer (c2) is extruded from the outer periphery of the insulator to form the outer layer 16. In the present embodiment, since the insulator and the outer layer 16 are formed of the elastomer component, no cross-linking treatment is required.

Then, by pulling out the spacer from the insulator, the hollow insulator 14 continuously formed in the longitudinal direction is formed. In the hollow insulator 14, the two electrode wires 13 are spirally wound along the inner peripheral surface of the hollow portion 15 in the longitudinal direction, and are arranged so as to face each other so as not to come into contact with each other.

From the above, the pressure-sensitive sensor 10 of the present embodiment is obtained.

<Effects of this embodiment>
In the pressure-sensitive sensor 10 of the present embodiment, the hollow insulator 14 is formed of an insulating composition (A) containing a styrene-based thermoplastic elastomer (a1), and the outer layer 16 is made of a thermoplastic polyurethane (c1) and an acid. It is formed of an insulating composition (C) containing a modified polymer (c2). By blending the component (c2) with the component (c1) to form the outer layer 16, the adhesiveness to the hollow insulator 14 containing the component (a1) can be enhanced. Further, according to the component (a1), since it is not necessary to perform the crosslinking treatment, the number of manufacturing steps of the pressure sensitive sensor 10 can be reduced and the cost can be reduced. Therefore, according to the present embodiment, a pressure-sensitive sensor 10 having excellent adhesion between the hollow insulator 14 and the outer layer 16 can be obtained without the need for cross-linking treatment.

Further, in the present embodiment, the conductive coating 12 of the electrode wire 13 is formed of the conductive composition (B) containing the styrene-based thermoplastic elastomer (b1) and the conductive agent (b2). That is, the conductive coating 12 and the hollow insulator 14 are formed of the same elastomer component. As a result, the adhesiveness between the hollow insulator 14 and the conductive coating 12 can be enhanced, and the peeling of the electrode wire 13 from the hollow insulator 14 can be suppressed even when the pressure-sensitive sensor 10 is repeatedly operated. .. Therefore, the long-term reliability of the pressure-sensitive sensor 10 can be improved.

The insulating composition (C) forming the outer layer 16 is 100 parts by mass in total of 30 parts by mass to 99 parts by mass of the thermoplastic polyurethane (c1) and 1 part by mass to 70 parts by mass of the acid-modified polymer (c2). It is preferable to contain a portion. As a result, it is possible to maintain high mechanical properties and flexibility inherent in the component (c1) in the outer layer 16 while ensuring the adhesiveness of the outer layer 16 to the hollow insulator 14.

It is preferable that the thermoplastic polyurethane (c1) is a polyether polyurethane. As a result, the moisture and heat resistance of the outer layer 16 can be enhanced, and the high temperature operability of the pressure sensor 10 can be enhanced.

The acid-modified polymer (c2) preferably has a compression set of 70% or less at 70 ° C. according to JIS K6262. As a result, the compression set in the outer layer 16 can be set to 60% or less, the compression set in a high temperature environment can be reduced, and the high temperature operability and long-term reliability of the pressure sensor 10 can be improved.

The styrene-based thermoplastic elastomer (a1) preferably has a compression set of 30% or less at 70 ° C. according to JIS K6262. As a result, the compression set of the hollow insulator 14 in a high temperature environment can be reduced, and the high temperature operability and long-term reliability of the pressure sensitive sensor 10 can be improved.

In the hollow portion 15 of the hollow insulator 14, it is preferable that the plurality of electrode wires 13 are spirally opposed to each other so as not to come into contact with each other. By spirally winding the plurality of electrode wires 13 over the longitudinal direction of the pressure-sensitive sensor 10, the electrode wires 13 can be arranged to face each other at any position in the longitudinal direction of the pressure-sensitive sensor 10. Therefore, even when the number of electrode wires 13 is reduced to two in order to increase the flexibility of the pressure sensor 10, the sensitivity of the pressure sensor 10 can be maintained.

<Other embodiments>
Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment and can be appropriately modified without departing from the gist thereof.

In the above-described embodiment, the case where the two electrode wires are arranged so as to be spirally wound over the longitudinal direction has been described, but the number of the electrode wires and the arrangement thereof are not particularly limited. For example, four electrode wires may be used and arranged linearly so that they do not come into contact with each other.

Further, in the above-described embodiment, the case where the hollow insulator and the outer layer are extruded separately has been described, but the two layers are simultaneously extruded on the outer periphery of the core in which the electrode wire and the spacer are twisted. You may.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

The materials used in this example are as follows.

The following three types were used as the styrene-based thermoplastic elastomer (a1).
(A1-1) Ingredient: Styrene-based thermoplastic elastomer (“AR-1050” manufactured by Aronkasei Co., Ltd., compression set (70 ° C. × 24h) 12%)
(A1-2) Component: Styrene-based thermoplastic elastomer (“AR-AR-720” manufactured by Aronkasei Co., Ltd., compression set (70 ° C. × 24h) 28%)
(A1-3) Ingredients: Styrene-based thermoplastic elastomer (“AR-750” manufactured by Aronkasei Co., Ltd., compression set (70 ° C. × 24h) 31%)

As the olefin-based thermoplastic elastomer, “LVG9608N” manufactured by RIKEN TECHNOS CORPORATION (compression set (70 ° C. × 24 h) 15%) was used.

The following was used as the conductive material (B) containing the styrene-based thermoplastic elastomer (b1) and the conductivity-imparting agent (b2).
Conductive styrene-based thermoplastic elastomer ("AR-EL2-D30B" manufactured by Aronkasei Co., Ltd., containing carbon black)

As the thermoplastic polyurethane (c1), an ether-based polyurethane (“Elastran 1180A, compression set (70 ° C. × 24h) 45%” manufactured by BASF Japan Ltd.) was used.

The following was used as the acid-modified polymer (c2).
(C2-1) Component: Maleic anhydride copolymerized ethylene ethyl acrylate (“Bondain LX4110” manufactured by Arkema Co., Ltd., compression set (70 ° C. × 24h) 48%)
(C2-2) Component: Maleic anhydride-modified SEBS ("Tough Tech H1041" manufactured by Asahi Kasei Chemicals Co., Ltd., compression set (70 ° C. x 24h) 70%)
(C2-3) Component: Maleic anhydride-modified ethylene vinyl acetate ("Modic AP A515" manufactured by Mitsubishi Chemical Corporation, compression set (70 ° C. x 24h) 81%)

<Manufacturing of pressure sensor>
First, an electrode wire was prepared. Specifically, a conductive styrene-based thermoplastic elastoma is extruded on the outer circumference of a twisted conductor having an outer diameter of 0.127 mm composed of seven copper strands so that the outer diameter of the wire is 0.8 mm, and an electrode wire is formed. Made. Subsequently, around one spacer wire having the same outer diameter, two electrode wires are placed around it, four spacer wires having the same outer diameter are placed around the center, and two spacer wires are provided between the electrode wires in the circumferential direction. The core was made by arranging them so as to be sandwiched and twisting them together. Then, the insulating composition (A) used for the hollow insulator having the composition shown in Table 1 and the insulating composition (C) used for the outer layer are simultaneously extruded to the outer periphery of the core, and the outer diameter of the hollow insulator is 4 mm and the outer layer is formed. Was extruded so that the thickness of each was 0.3 mm. Then, the wire for the spacer was pulled out to manufacture a pressure-sensitive sensor.

In Examples 1 to 11 and Comparative Examples 1 and 2, as shown in Table 1 below, pressure-sensitive sensors were produced in the same manner except that the material for forming the hollow insulator or the material for forming the outer layer was appropriately changed.

<Evaluation method>
The produced pressure-sensitive sensor was evaluated by the following method.

(Adhesion between hollow insulator and electrode wire)
As shown in FIG. 3, for the adhesiveness between the hollow insulator and the electrode wire, a stainless steel round bar 20 having a diameter of 4 mm is arranged at right angles to the pressure sensor 10, and the pressure sensor 10 and the round bar 20 are brought into contact with each other. A test was conducted in which the pressure sensor 10 was repeatedly compressed from the state of being in a state of being evaluated. Specifically, the stroke length is 2 mm, the frequency is 1 Hz, the number of compressions is 10,000 times, and the pressure-sensitive sensor 10 is repeatedly compressed. I observed. In this embodiment, if it is not peeled off, it is judged to be acceptable and marked as 〇, and if it is peeled off, it is judged to be rejected and marked as ×.

(Adhesion between hollow insulator and outer layer)
The adhesiveness between the hollow insulator and the outer layer was evaluated by preparing the sample shown in FIG. Specifically, the hollow portion of one terminal of the pressure sensitive sensor 10 is sealed with a UV curable resin, and a polyamide resin (“Lenny 1002F” manufactured by Mitsubishi Engineering Plastics Co., Ltd., glass fiber: 30% by mass) is injection molded. The molded body 30 was formed. The molded body 30 had a diameter of 15 mm, a length of 20 mm, and an insertion length of the pressure sensor 10 of 15 mm. In this embodiment, if the appearance is good after molding, it is judged to be acceptable, and if the polyamide resin flows between the hollow insulator and the outer layer and the appearance is poor, it is judged to be unacceptable. Notated.

(Compression set of outer layer)
A sheet sample was separately prepared with the same composition as the outer layer of the pressure-sensitive sensor, and the compression set according to JIS K6262 was measured for this sheet sample. In this example, the test temperature was 70 ° C. and the test time was 24 hours. The lower the value of compression set, the more the original shape is restored.

(Compression resistance in high temperature environment)
As shown in FIG. 3, a stainless steel round bar 20 having a diameter of 4 mm is arranged at a right angle to the pressure sensor 10, and the pressure sensitive sensor 10 and the round bar 20 are compressed by 2 mm from the contact state, and this state is maintained. It was left in a constant temperature bath at 90 ° C. for 24 hours. After 24 hours had passed, the mixture was cooled to room temperature, the round bar 20 was removed from the pressure sensor 10, and the presence or absence of continuity between the electrode lines was measured using an ohmmeter. Those without continuity were regarded as acceptable, and those with contact between the electrode wires and conduction were regarded as rejected. If it failed, the test temperature was lowered by 10 ° C. and the test was carried out until it passed. The higher the passing temperature, the better the compression resistance in a high temperature environment.

<Evaluation result>
The evaluation results are shown in Table 1. As shown in Table 1, in Examples 1 to 11, it was confirmed that high adhesiveness could be obtained between the hollow insulator and the outer layer without performing the cross-linking treatment. In addition, it was confirmed that high adhesiveness can be obtained because both the conductive coating and the hollow insulator are formed of a styrene-based thermoplastic elastomer.
According to Examples 1 to 3, it was confirmed that the smaller the compression set of the elastomer component contained in the hollow insulator, the better the compression resistance of the pressure-sensitive sensor in a high temperature environment.
According to Examples 1, 4 and 5, the smaller the compression set of the acid-modified polymer (c2) contained in the outer layer, the smaller the compression set in the outer layer, and thus the compression resistance of the pressure sensor in a high temperature environment. It was confirmed that the sex could be improved.
According to Examples 4, 6 and 7, the smaller the amount of the acid-modified polymer (c2) contained in the outer layer and the higher the ratio of the thermoplastic polyurethane (c1), the smaller the compression set in the outer layer can be, and the more the feeling. It was confirmed that the compression resistance of the pressure sensor in a high temperature environment can be improved. The blending amount of the component (c2) may be 100 parts by mass in total with the component (c1), but the compression resistance of the pressure-sensitive sensor can be improved while maintaining the adhesiveness between the hollow insulator and the outer layer. From the viewpoint of increasing, it was confirmed that 1 part by mass to 10 parts by mass should be used.
As shown in Examples 8 to 11, the ratio of the acid-modified polymer (c2) to the thermoplastic polyurethane (c1) may be increased. According to Examples 8 and 9, when (c2-1) was used as the acid-modified polymer, the compounding amount was 40 parts by mass to 60 parts by mass with respect to 100 parts by mass in total with the component (c1). It was confirmed that the same evaluation results as in Example 1 were obtained. According to Examples 10 and 11, when (c2-2) is used as the acid-modified polymer, even if the blending amount is 40 parts by mass to 60 parts by mass with respect to 100 parts by mass in total with the component (c1), it is hollow. It was confirmed that the pressure-sensitive sensor can obtain compression resistance while maintaining the adhesiveness between the insulator and the outer layer.

On the other hand, in Comparative Example 1, since the hollow insulator was formed of the olefin-based thermoplastic elastomer instead of the styrene-based thermoplastic elastomer (a1), not only the adhesiveness to the outer layer containing the thermoplastic polyurethane (c1) could not be obtained. It was confirmed that sufficient adhesiveness could not be obtained even with the electrode wire.
Further, in Comparative Example 2, it was confirmed that since the acid-modified polymer (c2) was not blended in the outer layer, sufficient adhesiveness could not be obtained with the hollow insulator containing the styrene-based thermoplastic elastomer (a1). rice field.

As described above, in the pressure-sensitive sensor, the hollow insulator is formed of the insulating composition (A) containing the styrene-based thermoplastic elastomer (a1), and the outer layer is formed of the thermoplastic polyurethane (c1) and the acid-modified polymer (c2). ) Is formed in the insulating composition (C), so that the desired adhesiveness can be obtained between the hollow insulator and the outer layer. Further, by forming the conductive coating of the electrode wire with the insulating composition (B) containing the styrene-based thermoplastic elastomer (b1), desired adhesion can be obtained between the hollow insulator and the electrode wire. Further, since the component (a1) does not need to be subjected to a crosslinking treatment, the crosslinking treatment can be omitted in the manufacture of the pressure-sensitive sensor, and the number of steps can be reduced. Therefore, according to the present invention, it is possible to obtain a pressure-sensitive sensor that does not require a cross-linking treatment and has excellent adhesiveness and long-term reliability between the hollow insulator and the outer layer.

<Preferable Aspect of the Present Invention>
Hereinafter, preferred embodiments of the present invention will be described.

<Appendix 1>
An elastically deformable long hollow insulator in which hollow portions are continuously formed in the longitudinal direction,
Conductive to the outer periphery of the conductor, which is provided along the inner peripheral surface of the hollow portion in the longitudinal direction and is arranged so as to be separated from each other so as to come into contact with each other when bent due to elastic deformation of the hollow insulator. Multiple electrode wires provided with a coating and
An outer layer formed so as to cover the outer periphery of the hollow insulator is provided.
The hollow insulator is formed of an insulating composition (A) containing a styrene-based thermoplastic elastomer (a1).
The outer layer is a pressure sensitive sensor formed of an insulating composition (C) containing a thermoplastic polyurethane (c1) and an acid-modified polymer (c2) modified with an unsaturated carboxylic acid or a derivative thereof.

<Appendix 2>
In the pressure sensor of Appendix 1, preferably
The insulating composition (C) forming the outer layer contains 30 parts by mass or more and 99 parts by mass or less of the thermoplastic polyurethane (c1) and 1 part by mass or more and 70 parts by mass or less of the acid-modified polymer (c2). Is contained in 100 parts by mass in total.

<Appendix 3>
In the pressure sensor of Appendix 2, preferably
The insulating composition (C) forming the outer layer contains 40 parts by mass or more and 95 parts by mass or less of the thermoplastic polyurethane (c1) and 5 parts by mass or more and 60 parts by mass or less of the acid-modified polymer (c2). Is contained in 100 parts by mass in total.

<Appendix 4>
In the pressure-sensitive sensors of Attachments 1 to 3, preferably
The thermoplastic polyurethane (c1) is a polyether polyurethane.

<Appendix 5>
In the pressure-sensitive sensors of Appendix 1 to 4, preferably
The acid-modified polymer (c2) has a compression set of 70% or less at 70 ° C. according to JIS K6262.

<Appendix 6>
In the pressure-sensitive sensors of Addendums 1 to 5, preferably
The outer layer has a compression set of 60% or less at 70 ° C. according to JIS K6262.

<Appendix 7>
In the pressure-sensitive sensors of Addendums 1 to 6, preferably
The styrene-based thermoplastic elastomer (a1) has a compression set of 30% or less at 70 ° C. according to JIS K6262.

<Appendix 8>
In the pressure-sensitive sensors of Addendums 1 to 7, preferably
The styrene-based thermoplastic elastomer (a1) does not contain a double bond in the molecular chain.

<Appendix 9>
In the pressure sensor of Appendix 8, preferably
The styrene-based thermoplastic elastoma (a1) is a styrene-ethylene-butylene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, and a styrene-ethylene-ethylene-propylene-styrene block copolymer. At least one.

<Appendix 10>
In the pressure-sensitive sensors of Addendums 1 to 9, preferably
The plurality of electrode wires are spirally arranged to face each other so as not to come into contact with each other in the hollow portion.

10 Pressure sensor 11 Conductor 12 Conductive coating 13 Electrode line 14 Hollow insulator 15 Hollow part 16 Outer layer 20 Round bar 30 Molded body

Claims (2)

An elastically deformable long hollow insulator in which hollow portions are continuously formed in the longitudinal direction,
Conductive to the outer periphery of the conductor, which is provided along the inner peripheral surface of the hollow portion in the longitudinal direction and is arranged so as to be separated from each other so as to come into contact with each other when bent due to elastic deformation of the hollow insulator. Multiple electrode wires provided with a coating and
An outer layer formed so as to cover the outer periphery of the hollow insulator is provided.
The hollow insulator is formed of an insulating composition (A) containing a styrene-based thermoplastic elastomer (a1) having a compressive strain of 12% or more and 31% or less at 70 ° C. according to JIS K6262.
The outer layer is modified with a thermoplastic polyurethane (c1) formed of a polyether polyurethane and an unsaturated carboxylic acid or a derivative thereof, and is an acid having a compression set of 48% or more and 81% or less at 70 ° C. in accordance with JIS K6262. Formed from the insulating composition (C) comprising the modified polymer (c2),
The styrene-based thermoplastic elastoma (a1) forming the hollow insulator is a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-isoprene-butadiene-styrene block copolymer, and the like. Formed from at least one of a styrene-ethylene-butylene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, and a styrene-ethylene-ethylene-propylene-styrene block copolymer.
The insulating composition (C) forming the outer layer contains 90 parts by mass or more and 99 parts by mass or less of the thermoplastic polyurethane (c1) and 1 part by mass or more and less than 10 parts by mass of the acid-modified polymer (c2). A pressure-sensitive sensor containing 100 parts by mass in total. Wherein the plurality of electrode lines are opposed to helically as not to contact each other at the hollow portion, the pressure sensor according to claim 1.

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