JP2020066641A - Rubber composition for actuator, vulcanized rubber for actuator and actuator - Google Patents

Abstract

To provide a rubber composition for an actuator and a vulcanized rubber for an actuator, excellent in workability and capable of producing an actuator excellent in an abrasion resistance to a sleeve, and an actuator excellent in an abrasion resistance to a sleeve.SOLUTION: A rubber composition for an actuator includes: a rubber component containing 60 mass% or more and less than 100 mass% diene rubber having a glass transition temperature of -85°C or lower; carbon black having a nitrogen adsorption specific surface area of 75 to 180 m/g and DBP oil absorption of 100 to 140 cm/100 g; a vulcanization accelerator; and sulfur. A content of the carbon black is 30 to 80 pts.mass based on the rubber component 100 pts.mass. A total amount of the vulcanization accelerator and the sulfur is 1.5 pts.mass or more based on the rubber component 100 pts.mass. As a vulcanized rubber characteristic thereof, a tensile elastic modulus is 4.5 MPa or more when elongated at 25°C by 200%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rubber composition for an actuator, a vulcanized rubber for an actuator, and an actuator.

Conventionally, as an actuator for expanding and contracting a tube, a pneumatic tube having a rubber tube (tubular body) that expands and contracts by using air as a fluid and a sleeve (braided reinforcing structure) that covers the outer peripheral surface of the tube An actuator (so-called McKibben type) is widely used (for example, see Patent Document 1).
Further, as an actuator with improved tube durability, an actuator including a tube having a laminated structure of two or more layers composed of a polar rubber layer and a nonpolar rubber layer having different SP values is disclosed (for example, Patent Document 1). 2).

JP 61-236905 A International Publication No. 2018/084123

Both ends of the actuator body formed by the tube and the sleeve are crimped by using a sealing member made of metal.
The sleeve is a tubular structure in which high-tensile fiber such as polyamide fiber or a metal cord is woven, and restricts the expansion motion of the tube within a predetermined range.
Such a pneumatic actuator is used in various fields, and particularly, it is preferably used as an artificial muscle of a care / welfare device, but there is room for improvement in wear resistance to a sleeve.

  An object of the present invention is to provide a rubber composition for an actuator and a vulcanized rubber for an actuator, which are excellent in workability and which can produce an actuator having excellent wear resistance to a sleeve, and an actuator having excellent wear resistance to a sleeve. The problem is to solve the object.

<1> A rubber component containing 60% by mass or more and less than 100% by mass of a diene rubber having a glass transition temperature of −85 ° C. or less,
Nitrogen adsorption specific surface area of 75~180m ² / g, DBP oil absorption comprises carbon black is 100~140cm ³ / 100g, and a vulcanization accelerator and sulfur,
The content of the carbon black is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component, and the total amount of the vulcanization accelerator and the sulfur is more than 1.5 parts by mass,
A rubber composition for an actuator, which has a vulcanized rubber property of having a modulus tensile elastic modulus of 4.5 MPa or more when stretched 200% at 25 ° C.

<2> The rubber composition for an actuator according to <1>, wherein the diene rubber is butadiene rubber.
<3> The rubber composition for an actuator according to <1> or <2>, in which the rubber component contains natural rubber.
<4> Any one of <1> to <3>, wherein a mass ratio (s / a ratio) between the sulfur content s and the vulcanization accelerator content a is 0.95 to 3.0. The rubber composition for an actuator according to item 4.

<5> A vulcanized rubber for an actuator, which uses the rubber composition for an actuator according to any one of <1> to <4>.

<6> A tubular tube that expands and contracts due to hydraulic pressure or air pressure, and a sleeve that is a tubular structure in which cords oriented in a predetermined direction are woven and that covers the outer peripheral surface of the tube. An actuator comprising an actuator main body and using the vulcanized rubber for actuator according to <5> in the tube.

<7> The actuator according to <6>, wherein the tube has a single layer structure.

<8> The actuator according to <6> or <7>, wherein the tube has a layer thickness of 1.0 to 15.0 mm.
<9> The actuator according to <6>, wherein the tube has a multilayer structure.
<10> The actuator according to <9>, wherein the vulcanized rubber for actuator according to <5> is used for the outermost layer of the tube.

  According to the present invention, it is possible to provide a rubber composition for an actuator and a vulcanized rubber for an actuator, which can manufacture an actuator having excellent workability and excellent wear resistance to a sleeve, and an actuator having excellent wear resistance to a sleeve. it can.

3 is a side view of an embodiment of actuator 10. FIG. 3 is a partially exploded perspective view of an embodiment of the actuator 10. FIG. FIG. 4 is a partial cross-sectional view of one embodiment of tube 110.

Hereinafter, the present invention will be described in detail based on its embodiments.
In addition, in the following description, the description of “A to B” indicating a numerical range indicates a numerical range including A and B which are end points, and is “A or more and B or less” (when A <B), or “A “B or more” (when B <A).
Moreover, a mass part and mass% are synonymous with a weight part and weight%, respectively.

<Actuator>
The actuator of the present invention comprises a tubular tube that expands and contracts by hydraulic pressure or air pressure, and a sleeve that is a tubular structure in which cords oriented in a predetermined direction are woven and that covers the outer peripheral surface of the tube. It is an actuator comprising a structured actuator body and using the vulcanized rubber for an actuator of the present invention in the tube.
The vulcanized rubber for actuators of the present invention is the vulcanized rubber of the rubber composition for actuators of the present invention. Details of the rubber composition for actuators and the vulcanized rubber for actuators will be described later.

  Hereinafter, an actuator of the present invention will be described in detail based on an embodiment thereof with reference to the drawings. Note that the same functions and configurations are given the same or similar reference numerals, and description thereof will be omitted as appropriate.

(1) Overall Schematic Configuration of Actuator FIG. 1 is a side view of an actuator 10 according to the present embodiment. As shown in FIG. 1, the actuator 10 includes an actuator body 100, a sealing mechanism 200, and a sealing mechanism 300. Further, the connecting portions 20 are provided at both ends of the actuator 10, respectively.

The actuator body 100 includes a tube 110 and a sleeve 120. The working fluid flows into the actuator body 100 through the fitting 400 and the passage hole 410. Here, the actuator of the present invention may be a hydraulic type or a pneumatic type.
In the case of the hydraulic type, a liquid is used as the working fluid, and examples of the liquid include oil and water. When the actuator of the present invention is used as a hydraulic actuator, the hydraulic actuator may be hydraulic or hydraulic. In the case of the hydraulic type, as the hydraulic oil, the hydraulic oil conventionally used in the hydraulic drive system can be used.
In the case of the pneumatic type, compressed air is used as the working fluid.

  The actuator 10 includes a tube 110 with the vulcanized rubber for actuator of the present invention obtained by vulcanizing the rubber composition for actuator of the present invention. The vulcanized rubber for actuator has a modulus tensile elastic modulus of 4.5 MPa or more when it is expanded by 200% at 25 ° C., and therefore has high durability that can withstand hydraulic drive in which a high pressure is applied to the actuator body 100. Therefore, the actuator 10 is preferably a hydraulic type.

  When the working fluid flows into the tube 110, the actuator body 100 contracts in the axial direction DAX of the actuator body 100 and expands in the radial direction DR. Further, the actuator body 100 expands in the axial direction DAX of the actuator body 100 and contracts in the radial direction DR when the working fluid flows out from the tube 110. The actuator 10 exerts its function as an actuator due to such a change in the shape of the actuator body 100.

  Further, such an actuator 10 is of a so-called McKibben type, and can be applied not only to artificial muscles but also to body limbs (upper limbs, lower limbs, etc.) of a robot that requires higher performance (contraction force). It can be preferably used. The members forming the body limb are connected to the connecting portion 20.

  The sealing mechanism 200 and the sealing mechanism 300 seal both ends of the actuator body 100 in the axial direction DAX. Specifically, the sealing mechanism 200 includes a sealing member 210 and a caulking member 230. The sealing member 210 seals the end of the actuator body 100 in the axial direction DAX. Further, the caulking member 230 caulks the actuator body 100 together with the sealing member 210. An indentation 231 is formed on the outer peripheral surface of the caulking member 230, which is a mark of caulking the caulking member 230 with a jig.

The difference between the sealing mechanism 200 and the sealing mechanism 300 is whether or not the fitting 400 (and the passage hole 410) is provided.
The fitting 400 is protruded so that a hose (pipe line) connected to a driving pressure source of the actuator 10, specifically, a compressor for working fluid can be attached. The working fluid that has flowed in via the fitting 400 passes through the passage hole 410 and flows into the inside of the actuator body 100, specifically, the inside of the tube 110.

FIG. 2 is a partially exploded perspective view of the actuator 10. As shown in FIG. 2, the actuator 10 includes an actuator body 100 and a sealing mechanism 200.
The actuator body 100 is composed of the tube 110 and the sleeve 120 as described above.

The tube 110 is a cylindrical body that expands and contracts due to hydraulic pressure. Since the tube 110 repeatedly contracts and expands due to the working fluid, it repeatedly contacts the sleeve 120. However, since the vulcanized rubber for actuator of the present invention is used for the tube 110, the tube 110 has excellent wear resistance.
The tube 110 may have a single-layer structure or a multi-layer structure.
When the actuator 10 is used as a hydraulic actuator, the tube 110 preferably has a multi-layer structure. By using the inner layer that contacts the flowing liquid as a water-resistant or oil-resistant layer and using the vulcanized rubber for actuator of the present invention as the outermost layer that contacts the sleeve 120, it has durability against the flowing liquid and at the same time, has a durability against the sleeve 120. It can have abrasion resistance.

FIG. 3 is a partial cross-sectional view of one embodiment of tube 110.
The tube 110 shown in FIG. 3 has a two-layer structure including an inner layer 111 located on the inner surface side of the tube and an outermost layer 112 located on the outer surface side of the tube 110 adjacent to the outer side in the radial direction DR of the inner layer 111. Have.

At least one of the inner layer 111 and the outermost layer 112 may contain the vulcanized rubber for actuator of the present invention, and both may contain the vulcanized rubber for actuator of the present invention. When the vulcanized rubber for actuator of the present invention is used for both the inner layer 111 and the outermost layer 112, for example, two kinds of vulcanized rubber for actuator of the present invention having different tensile elastic moduli may be used for each layer.
Among them, as described above, it is preferable that the inner layer that contacts the flowing liquid be a water-resistant or oil-resistant layer and the vulcanized rubber for actuator of the present invention be used as the outermost layer that contacts the sleeve 120. In other words, the outermost layer 112, a radial direction D _R outside of the inner layer 111, which is preferably disposed on the outermost side of the tube 110. The outermost layer 112, that is disposed radially _{D R} outside of the inner layer 111, the outermost layer 112 which is excellent in wear resistance withstand load from the sleeve 120 side, the inner layer 111 is protected and the strength of the entire tube 110 And the durability of the tube 110 is further improved.

Specifically, by making the inner layer 111 a rubber layer containing polar rubber, for example, it has excellent liquid resistance, particularly oil resistance, and has high durability even if the working fluid is oil, for example. .
On the other hand, when the outermost layer 112 is a rubber layer containing the vulcanized rubber for an actuator of the present invention, it bears a load from the sleeve 120 side and has high durability even if it contacts the sleeve 120, for example.
Therefore, since the tube 110 has a laminated structure of two or more layers including the inner layer 111 and the outermost layer 112, it is possible to realize an actuator that has high liquid resistance and durability even when repeatedly expanded and contracted.

  The polar rubber used for the inner layer 111 is not particularly limited. Rubber)), chloroprene rubber (CR), epichlorohydrin rubber, and the like. These polar rubbers may be used alone or in combination of two or more.

The inner layer 111 preferably contains acrylonitrile-butadiene rubber and / or hydrogenated acrylonitrile-butadiene rubber. Among the polar rubbers, the acrylonitrile-butadiene rubber and hydrogenated acrylonitrile-butadiene rubber have particularly high oil resistance and excellent processability. Therefore, when the inner layer 111 contains acrylonitrile-butadiene rubber and / or hydrogenated acrylonitrile butadiene rubber, the oil resistance of the inner layer 111 is further improved. Further, the acrylonitrile-butadiene rubber and the hydrogenated acrylonitrile-butadiene rubber are preferable because the nitrile content, that is, the content of the acrylonitrile unit is 20% by mass to 50% by mass, because the oil resistance is further enhanced. Acrylonitrile-butadiene rubber and / or hydrogenated acrylonitrile butadiene rubber are generally low nitrile type having an acrylonitrile unit content of less than 25% by mass, and medium nitrile type having an acrylonitrile content of 25% by mass or more and less than 35% by mass. , And is classified as a high nitrile type having an acrylonitrile unit content of 35 mass% or more.
The acrylonitrile-butadiene rubber and / or hydrogenated acrylonitrile-butadiene rubber preferably contains two or more types of acrylonitrile-butadiene rubber and / or hydrogenated acrylonitrile-butadiene rubber having different acrylonitrile unit contents. The desired nitrile content can be easily achieved by using two or more types of acrylonitrile-butadiene rubber and / or hydrogenated acrylonitrile-butadiene rubber.
The content ratio of the acrylonitrile-butadiene rubber (NBR) and hydrogenated acrylonitrile butadiene rubber (hydrogenated NBR) in the rubber component of the inner layer 111 is preferably 50 to 100% by mass, and 60 to 90% by mass. Is more preferable.

  Hydrogenated acrylonitrile-butadiene rubber is obtained by adding hydrogen to acrylonitrile-butadiene rubber. Hydrogenated acrylonitrile-butadiene rubber is generally preferable because it has the same oil resistance as acrylonitrile-butadiene rubber and is superior in heat resistance and the like to acrylonitrile-butadiene rubber.

  Among the polar rubbers, chloroprene rubber is preferable because it is excellent in mechanical properties such as tensile strength and elongation and workability.

  Among the polar rubbers, epichlorohydrin rubber is preferable because it is excellent in ozone resistance and adhesiveness.

  The tube 110 shown in FIG. 3 includes only the inner layer 111 and the outermost layer 112, but may have one or more intermediate layers between the inner layer 111 and the outermost layer 112. Examples of the intermediate layer include functional layers containing various functional components such as an adhesive layer that improves the adhesiveness between the inner layer 111 and the outermost layer 112. For the adhesive layer, an appropriate adhesive may be used depending on the properties of the inner layer 111 and the outermost layer 112. For example, "Metalock R-17" manufactured by Toyo Kagaku Kenkyusho Co., Ltd. may be preferably used.

Further, in the present invention, the layer thickness of the tube 110 is preferably 1.0 to 15.0 mm from the viewpoint of durability and operating length of the actuator. When the layer thickness of the tube 110 is 1.0 mm or more, the durability of the tube 110 is excellent. When the layer thickness of the tube 110 is 15.0 mm or less, the tube 110 has excellent expandability and input responsiveness. Excel. The diameter (outer diameter) of the tube 110 can be appropriately selected according to the intended use.
The layer thickness of the tube 110 means the total thickness of the tube 110, and when the tube 110 is a multilayer, it means the total layer thickness of all layers. For example, the tube 110 is if a two-layer structure consisting of an inner layer 111 and the outermost layer 112. shown in FIG. 3, the thickness in the radial direction of the inner layer 111 and the outermost layer 112 _{(D R} direction), thickness of the tube 110 And
The layer thickness of the tube 110 is more preferably 1.5 to 13.0 mm from the viewpoint of further improving the input response and wear resistance of the actuator.

  When the tube 110 has a multi-layer structure, the total thickness of the inner layer 111 is preferably 10% to 90% of the total thickness of the tube 110, more preferably 20% to 80%, and the outermost layer 112. The total thickness is preferably 90% to 10% of the total thickness of the tube 110, and more preferably 80% to 20%. In this case, the liquid resistance and durability of the tube 110 are improved, and the wear resistance of the sleeve 120 is further improved.

  The sleeve 120 has a cylindrical shape and covers the outer peripheral surface of the tube 110. The sleeve 120 is a structure in which cords oriented in a predetermined direction are woven, and a rhombus shape is repeated by intersecting the oriented cords. By having such a shape, the sleeve 120 is pantograph-deformed and follows the tube 110 while restricting the contraction and expansion of the tube 110.

As the cord 121 constituting the sleeve 120, polyamide fibers such as aramid fiber (aromatic polyamide fiber), polyhexamethylene adipamide (nylon 6,6) fiber, polycaprolactam (nylon 6) fiber, polyethylene terephthalate (PET) It is preferable to use a fiber cord made of at least one fiber material selected from fibers, polyester fibers such as polyethylene naphthalate (PEN) fibers, polyurethane fibers, rayon, acrylic fibers, and polyolefin fibers. Among these, from the viewpoint of the strength of the sleeve 120, it is particularly preferable to use a cord made of aramid fiber.
However, the present invention is not limited to such a kind of fiber cord. For example, a high strength fiber such as PBO (polyparaphenylenebenzobisoxazole) fiber or a metal cord composed of an ultrafine filament is used. Good.

The surface of the above-mentioned fiber cord or metal cord may be covered with rubber, a mixture of a thermosetting resin and latex, or the like. When the surface of the cord is covered with these materials, the coefficient of friction of the surface of the cord can be appropriately reduced while improving the durability of the cord.
The solid content of the mixture of the thermosetting resin and the latex is preferably 15% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less. Further, examples of the thermosetting resin include phenol resin, resorcin resin, urethane resin, and the like, and examples of the latex include vinyl pyridine (VP) latex, styrene-butadiene rubber (SBR) latex, acrylonitrile-butadiene rubber (NBR) latex. Etc.

  The sleeve may have a single-layer structure or a multi-layer structure. In the latter case, even if the sleeves are laminated so that the cross-sections are concentric, the sleeves are wound in a spiral shape. It may be of a structured structure.

  In FIG. 2, the sealing mechanism 200 seals the end of the actuator body 100 in the axial direction DAX. The sealing mechanism 200 includes a sealing member 210, a locking ring 220, and a caulking member 230.

  The sealing member 210 has a body portion 211 and a flange portion 212. A metal such as stainless steel can be preferably used as the sealing member 210, but the sealing member 210 is not limited to such a metal, and a hard plastic material or the like may be used.

  The body portion 211 has a circular tubular shape, and a passage hole 215 through which a working fluid passes is formed in the body portion 211. The passage hole 215 communicates with the passage hole 410 (see FIG. 1). The tube 110 is inserted into the body portion 211.

  The collar portion 212 is connected to the body portion 211, and is located closer to the end portion side of the actuator 10 in the axial direction DAX than the body portion 211. The flange portion 212 has a larger outer diameter along the radial direction DR than the body portion 211. The collar portion 212 locks the tube 110 and the locking ring 220 inserted in the body portion 211.

  An uneven portion 213 is formed on the outer peripheral surface of the body portion 211. The uneven portion 213 contributes to suppressing slippage of the tube 110 inserted in the body portion 211. It is preferable that three or more convex portions are formed by the uneven portion 213.

  Further, a small diameter portion 214 having an outer diameter smaller than that of the body portion 211 is formed at a position near the flange portion 212 of the body portion 211.

The locking ring 220 locks the sleeve 120. The sleeve 120 may be folded back to the outside in the radial direction D _R via the locking ring 220.

The outer diameter of the locking ring 220 is larger than the outer diameter of the body portion 211. The locking ring 220 locks the sleeve 120 at the position of the small diameter portion 214 of the body portion 211. That is, the locking ring 220, a radial direction _{D R} outside of the body 211, in a position adjacent to the flange portion 212, locking the sleeve 120.

  Since the locking ring 220 is locked to the small diameter portion 214 smaller than the body portion 211, the locking ring 220 is divided into two in this embodiment. The locking ring 220 is not limited to be divided into two, but may be divided into a larger number of parts, or a part of the divided parts may be rotatably connected.

  As the locking ring 220, the same metal as the sealing member 210 or a hard plastic material can be used.

  The caulking member 230 caulks the actuator body 100 together with the sealing member 210. As the caulking member 230, a metal such as an aluminum alloy, brass and iron can be used. When the caulking member 230 is caulked by a caulking jig, an indentation 231 as shown in FIG. 1 is formed on the caulking member 230.

<Rubber composition for actuator>
The rubber composition for an actuator of the present invention has a rubber component containing a diene rubber having a glass transition temperature of −85 ° C. or less of 60% by mass or more and less than 100% by mass, and a nitrogen adsorption specific surface area of 75 to 180 m ² / g. and a carbon black having DBP oil absorption is 100~140cm ³ / 100g, the content of the carbon black, 30 to 80 parts by mass relative to 100 parts by mass of the rubber component, as vulcanized rubber properties, 25 The modulus of elasticity in modulus when stretched 200% at 40 ° C. is 4.5 MPa or more.
Hereinafter, the rubber composition for actuators may be simply referred to as “rubber composition”.
The vulcanized rubber has excellent wear resistance because the rubber composition for actuators has the above-mentioned constitution.
The reason for this is not clear, but it is presumed that the reason is as follows.

By containing a large amount of -85 ° C. diene rubber, wear powder becomes small, and it takes time to wear a certain amount, and the tensile modulus of elasticity is set to 4.5 MPa or more. It is presumed that the bite is suppressed.
Therefore, it is considered that by using the vulcanized rubber of the rubber composition for an actuator in the actuator (particularly, the tube), the actuator has excellent wear resistance to the sleeve.

[Rubber component]
The rubber composition of the present invention contains a rubber component containing 60% by mass or more and less than 100% by mass of a diene rubber having a glass transition temperature of −85 ° C. or less.
If the rubber component does not contain a diene rubber having a glass transition temperature of −85 ° C. or lower in an amount of 60% by mass or more, the vulcanized rubber is not excellent in abrasion resistance. On the other hand, when the content of the diene rubber in the rubber component is 100% by mass, the workability of the rubber composition deteriorates.
From the viewpoint of abrasion resistance of the vulcanized rubber, the content of the diene rubber having a glass transition temperature of −85 ° C. or less in the rubber component is preferably 65% by mass or more, and 70% by mass or more. Is more preferable, and 75% by mass or more is further preferable. Further, from the viewpoint of workability during kneading (rubber gathering property), the content of the diene rubber having a glass transition temperature of −85 ° C. or less in the rubber component is preferably 95% by mass or less, and 90% by mass or less. It is more preferable that the content is not more than mass%.

Examples of the diene rubber having a glass transition temperature (Tg) of −85 ° C. or lower include polybutadiene rubber (BR; Tg = −110 ° C. to −95 ° C.).
The polybutadiene rubber is not particularly limited as long as it is a polymer of a butadiene-based monomer, and may be one produced by using a plurality of types of butadiene-based monomers.
Examples of the butadiene-based monomer include 1,3-butadiene, 2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. Can be mentioned.

From the viewpoint of strength of the vulcanized rubber and workability of the rubber composition, the weight average molecular weight of the polybutadiene rubber is preferably 400,000 or more, and more preferably 450,000 or more. The upper limit is not particularly limited, but it is preferably 2 million or less.
In the present application, the weight average molecular weight (Mw) is obtained by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent in terms of standard polystyrene.

  The glass transition temperature (Tg) of the polybutadiene rubber is preferably −65 ° C. or lower, and more preferably −90 ° C. or lower. The lower limit of Tg of the polybutadiene rubber is not particularly limited, but is usually -130 ° C or higher. The Tg of the polybutadiene rubber is calculated by the midpoint method by measuring with a differential scanning calorimeter (DSC) at a temperature rising rate of 20 ° C./min.

The rubber component may further include a diene rubber having a glass transition temperature (Tg) of higher than -85 ° C.
Examples of the diene rubber having a Tg exceeding -85 ° C include natural rubber (NR; Tg = -79 ° C to -69 ° C), polyisoprene rubber (IR; Tg = -79 ° C to -69 ° C), styrene- Butadiene copolymer rubber (SBR; Tg = -55 ° C), chloroprene rubber (CR; Tg = -45 ° C to -43 ° C), butyl rubber (IIR; Tg = -75 ° C to -67 ° C), halogenated butyl rubber ( Br-IIR, Cl-IIR), acrylonitrile-butadiene rubber (NBR; Tg = -50 ° C) and the like.
Among the above, the diene rubber having a Tg of higher than −85 ° C. is preferably natural rubber or polyisoprene rubber, and more preferably natural rubber.
As the diene rubber having a Tg of higher than -85 ° C, one type may be used alone, or two or more types may be used.

The content of the diene rubber having a Tg of more than −85 ° C. in the rubber component is preferably 5% by mass or more, and more preferably 10% by mass or more, from the viewpoint of the wear resistance of the vulcanized rubber. , 15% by mass or more, more preferably less than 50% by mass, and even more preferably 45% by mass or less.
From the viewpoint of wear resistance of the vulcanized rubber, the rubber component preferably contains butadiene rubber and natural rubber, and more preferably consists of butadiene rubber and natural rubber.

  The rubber component may include a non-diene rubber. Examples of the non-diene rubber include ethylene propylene rubber (EPDM (also referred to as EPM)), maleic acid-modified ethylene propylene rubber (M-EPM), butyl rubber (IIR), isobutylene and an aromatic vinyl or diene monomer. Examples thereof include polymers, acrylic rubber (ACM), and ionomers.

〔Carbon black〕
The rubber composition of the present invention, as a filler, the nitrogen adsorption specific surface area of 75~180m ² / g, carbon black DBP oil absorption is 100~140cm ³ / 100g, based on 100 parts by mass of the rubber component Contains 30 to 80 parts by mass.
Hereinafter "nitrogen adsorption specific surface area of 75~180m ² / g, DBP oil absorption of carbon black is 100~140cm ³ / 100g" and may be referred to as "carbon black of the present invention".
When the content of the carbon black of the present invention in the rubber composition is less than 30 parts by mass with respect to 100 parts by mass of the rubber component, the vulcanized rubber does not have excellent abrasion resistance, and when it exceeds 80 parts by mass, kneading is performed. The workability at time deteriorates.
From the viewpoint of further improving the wear resistance of the vulcanized rubber, the content of the carbon black of the present invention in the rubber composition is preferably 30 to 70 parts by mass, and 40 to 40 parts by mass with respect to 100 parts by mass of the rubber component. The amount is more preferably 70 parts by mass, further preferably 50 to 70 parts by mass.

When the nitrogen adsorption specific surface area of carbon black is less than 75 m ² / g, the vulcanized rubber is not excellent in abrasion resistance. When the nitrogen adsorption specific surface area exceeds 180 m ² / g, the Mooney viscosity of the rubber composition increases and the workability is poor. From the viewpoint of further improving the workability of the rubber composition while further improving the abrasion resistance of the vulcanized rubber, the nitrogen adsorption specific surface area of carbon black is preferably 85 m ² / g or more, and 95 m ² / g. More preferably, it is more preferably 100 m ² / g or more. From the same viewpoint, the nitrogen adsorption specific surface area of carbon black is preferably 170 m ² / g or less, more preferably 160 m ² / g or less, and further preferably 150 m ² / g or less. .
The nitrogen adsorption specific surface area (N ₂ SA) can be measured by the method described in ASTM-D3037-86.

When DBP oil absorption of carbon black is less than 100 cm ^3/100 g, a vulcanized rubber properties and vulcanized rubber are not excellent in wear resistance. When DBP oil absorption is more than 140cm ^3/100 g increases the Mooney viscosity of the rubber composition is not excellent in workability. From the viewpoint of further improving the workability of the rubber composition while further improving the wear resistance of the vulcanized rubber, the DBP lubrication amount of carbon black is preferably 105 to 135 g / kg, and 110 to 130 g / kg. Is more preferable.
The DBP (dibutyl phthalate) oil absorption is measured by the method described in ASTM-D-3493, and is represented by the volume cm ³ of dibutyl phthalate (DBP) absorbed per 100 g of carbon black.

The carbon black of the present invention preferably has an iodine adsorption amount (IA) of 100 to 170 g / kg, and 110 to 150 g from the viewpoint of further improving the wear resistance of the vulcanized rubber and the input response of the actuator. / Kg is more preferable, and 115-140 g / kg is even more preferable.
The iodine adsorption amount can be measured by a method based on JIS K6221-1982.
Examples of the carbon black satisfying the above physical properties include SAF and ISAF, and ISAF is particularly preferable. These may be used alone or in combination of two or more.

(Other fillers)
The rubber composition of the present invention may contain other fillers, but the abrasion resistance of the vulcanized rubber and the content of the carbon black of the present invention in all the fillers exceed 50% by mass. It is preferably 70% by mass or more, more preferably 90% by mass or more, particularly preferably 100% by mass.
Other fillers include carbon black other than the carbon black of the present invention; metal oxides such as silica, alumina, zirconia and titania; aluminum hydroxide and the like.
When using other fillers, silica is preferable among the above, specifically, wet silica, calcined silica, precipitated silica, crushed silica, fused silica, anhydrous fine silicic acid, hydrous fine silicic acid, hydrous aluminum silicate. , Hydrous calcium silicate, special silica surface-treated with a silane coupling agent, etc. can be used according to the application. As silica, it is preferable to use wet silica.
When the rubber composition of the present invention contains silica, the rubber composition of the present invention may further contain a silane coupling agent.

〔sulfur〕
The rubber composition of the present invention contains sulfur.
From the viewpoint of improving the wear resistance of the vulcanized rubber, the rubber composition of the present invention preferably contains more than 0.8 parts by mass and 1.8 parts by mass or less of sulfur with respect to 100 parts by mass of the rubber component. .
When the content of sulfur in the rubber composition exceeds 0.8 parts by mass with respect to 100 parts by mass of the rubber component, as a vulcanized rubber property, the modulus tensile elastic modulus at 200% elongation at 25 ° C. is 4. It is easy to increase the pressure to 5 MPa or more, and the abrasion resistance of the vulcanized rubber can be improved. When the content of sulfur in the rubber composition is 1.8 parts by mass or less with respect to 100 parts by mass of the rubber component, sulfur bloom can be suppressed.
The content of sulfur in the rubber composition of the present invention is more preferably 1.2 to 1.8 parts by mass, and is 1.4 to 1.7 parts by mass with respect to 100 parts by mass of the rubber component. More preferably.

[Vulcanization accelerator]
The rubber composition of the present invention contains a vulcanization accelerator.
From the viewpoint of improving the wear resistance of the vulcanized rubber, the rubber composition of the present invention preferably contains 0.7 to 1.8 parts by mass of the vulcanization accelerator with respect to 100 parts by mass of the rubber component.
When the content of the vulcanization accelerator in the rubber composition is 0.7 parts by mass or more with respect to 100 parts by mass of the rubber component, the vulcanized rubber has a modulus tensile elasticity of 200% elongation at 25 ° C. The rate can easily be 4.5 MPa or more, and the abrasion resistance of the vulcanized rubber can be improved. When the content of the vulcanization accelerator in the rubber composition is 1.8 parts by mass or less with respect to 100 parts by mass of the rubber component, the vulcanization rate can be easily adjusted.
The content of the vulcanization accelerator in the rubber composition of the present invention is more preferably 0.8 to 1.5 parts by mass, and 0.8 to 1.3 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is a part.

The vulcanization accelerator is not particularly limited, but examples thereof include aldehyde / ammonia-based, guanidine-based, thiourea-based, thiazole-based, sulfenamide-based, thiuram-based, dithiocarbamate-based vulcanization accelerators and the like. Of these, sulfenamide-based vulcanization accelerators are particularly preferable.
Specific examples of the aldehyde / ammonia-based vulcanization accelerator include hexamethylenetetramine (H).
Specific examples of the guanidine vulcanization accelerator include diphenylguanidine and the like.
Specific examples of the thiourea-based vulcanization accelerator include ethylene thiourea.
Specific examples of the thiazole-based vulcanization accelerator include dibenzothiazyl disulfide (DM), 2-mercaptobenzothiazole and its Zn salt.
Specific examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolyl sulfenamide (CZ) and Nt-butyl-2-benzothiazolyl sulfenamide (NS ) And the like.
Specific examples of thiuram-based vulcanization accelerators include tetramethylthiuram disulfide (TMTD) and dipentamethylene thiuram tetrasulfide.
Specific examples of the dithiocarbamate vulcanization accelerator include Na-dimethyldithiocarbamate, Zn-dimethyldithiocarbamate, Te-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate, and pipecoline. Examples include pipecolyl dithiocarbamate.
The vulcanization accelerators may be used alone or in combination of two or more.

In the rubber composition of the present invention, the total amount of the vulcanization accelerator and sulfur is more than 1.5 parts by mass based on 100 parts by mass of the rubber component. That is, the total amount (s + a) of the sulfur content (s) and the vulcanization accelerator content (a) in the rubber composition is 1.5 <s + a (mass) relative to 100 parts by mass of the rubber component. (Part) relationship.
When s + a exceeds 1.5 parts by mass, the modulus tensile elastic modulus when stretched 200% at 25 ° C. can be 4.5 MPa or more, and the vulcanized rubber is excellent in abrasion resistance. s + a is preferably 1.0 part by mass or more.
From the viewpoint of suppressing the occurrence of reversion during overvulcanization, as a vulcanized rubber property, it is easy to set the modulus tensile modulus at 200% elongation at 25 ° C to 4.5 MPa or more, and improve the wear resistance of the vulcanized rubber. Therefore, the mass ratio (s / a ratio) between the content (s) of sulfur and the content (a) of the vulcanization accelerator in the rubber composition is 0.95 or more and 3.0 or less. preferable. From the same viewpoint, the s / a ratio is more preferably 1.1 to 2.5, further preferably 1.3 to 2.0.

  The rubber composition of the present invention, together with the above components, if necessary, a compounding agent usually used in the rubber industry, for example, a softening agent, stearic acid, zinc white, an antiaging agent, etc. It may be appropriately selected and contained within a range that does not harm.

The rubber composition of the present invention comprises a diene rubber having a Tg of −85 ° C. or less, carbon black of the present invention, sulfur, a vulcanization accelerator, and other components, and is blended in a Banbury mixer, a roll, an internal mixer, or the like. It can be produced by kneading with a kneader. It is preferable that the respective components to be blended in the production of the rubber composition of the present invention are blended in the amounts shown as the contents of the respective components in the rubber composition of the present invention.
The kneading of each component may be carried out in one step or in two or more steps.

<Vulcanized rubber for actuator>
A vulcanized rubber for an actuator is obtained by vulcanizing the rubber composition for an actuator of the present invention. The rubber composition for an actuator of the present invention has a modulus of elasticity of modulus of 4.5 MPa or more when stretched by 200% at 25 ° C. as a vulcanized rubber property. Therefore, the vulcanized rubber for an actuator of the present invention is 25 The modulus of elasticity in modulus when stretched 200% at 40 ° C. is 4.5 MPa or more.
The modulus tensile modulus (M200) of the vulcanized rubber when stretched 200% at 25 ° C is 4.5 MPa or more, so that the actuator has high durability that can withstand hydraulic drive in which high pressure is applied to the actuator body. Have.
The modulus tensile elastic modulus (M200) of the vulcanized rubber when stretched 200% at 25 ° C. is preferably 4.5 to 8.5 MPa from the viewpoint of further improving the wear resistance to the sleeve, and 5.5. More preferably, it is ˜7.5 MPa. Further, the modulus tensile elastic modulus (M300) of the vulcanized rubber when stretched 300% at 25 ° C. is preferably 8.0 MPa or more from the viewpoint of further improving the wear resistance to the sleeve.
The vulcanized rubber is obtained by vulcanizing the rubber composition of the present invention at a vulcanizing temperature of 140 to 200 ° C, for example. The vulcanization time is, for example, 5 to 60 minutes.

  Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for the purpose of illustrating the present invention and do not limit the present invention in any way.

<Preparation of rubber composition and preparation of vulcanized rubber test piece>
Each component was blended according to the formulation of Table 1 and kneaded with a Banbury mixer to prepare a rubber composition.
The obtained rubber composition was extruded by a 3-inch roll and further vulcanized and pressed to prepare a vulcanized rubber test piece having a width of 75 mm, a length of 150 mm and a thickness of 2 mm.

Details of the components in Table 1 are as follows.
(1) Rubber component / NR: Natural rubber, RSS # 4
・ BR: Polybutadiene rubber, manufactured by Ube Industries, Ltd., product name "UBEPOL-BR150L"

(2) Carbon black Carbon black 1: nitrogen adsorption surface area ^{_{(N 2 SA): 119m 2}} / g, DBP oil ^absorption: 114 cm 3/100 g
Carbon black 2: Nitrogen adsorption surface area ^{_{(N 2 SA): 29m 2}} / g, DBP oil ^absorption: 89cm 3/100 g
(3) Stearic acid: Shin-Nippon Rika Co., Ltd., trade name "Stearic acid 50S"
(4) Zinc oxide: Toho Zinc Co., Ltd., trade name "Ginrei SR"
(5) Wax: Seiko Chemical Co., Ltd., trade name "Santite S"
(6) Anti-aging agent: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, manufactured by Sumitomo Chemical Co., Ltd., trade name "ANTIGENE6C"
(7) Vulcanization accelerator: NS, N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Noccer NS-F"
(8) Sulfur: product name "Salfax 5" manufactured by Tsurumi Chemical Industry Co., Ltd.

<Production of actuator>
(1) For Example 3, the actuator was manufactured as follows.
1. Preparation of Tube A cylindrical single-layer tube having a length of 300 mm was prepared by processing the obtained rubber composition with an extrusion molding machine.

2. Manufacture of Sleeve Two 2200 dtex aramid fibers were used as the raw yarns, 12 times / 10 cm of lower twist was applied, and further 12 times / 10 cm of upper twist was applied to manufacture an aramid fiber cord having a diameter of 0.7 mm. A mesh-like sleeve produced by braiding 64 aramid fiber cords was prepared. This sleeve was a mesh-like tubular body in which 64 aramid fiber cords were observed on the circumference in the cross section. Specifically, this sleeve has 32 aramid fiber cords arranged at equal intervals in parallel and spirally, and the 32 aramid fiber cords obliquely intersect with each other and arranged at equal intervals in parallel and spirally. The other 32 aramid fiber cords thus produced were alternately knitted into a mesh tubular body, and the angle of each cord with respect to the axial direction of the sleeve was 25 degrees.

3. Manufacture of Actuator An actuator having a structure shown in FIGS. 1 and 2 was manufactured using the tube and the mesh sleeve. The length between the sealing mechanism 200 and the sealing mechanism 300 is 250 mm. As the hydraulic oil for the tube incorporated in the actuator, UF46 manufactured by Cosmo Super Epoch Co., Ltd. was used.
It was confirmed that there was no problem in input responsiveness.

(2) For Examples 1, 2, 4, 5 and Comparative Examples 1 to 6, actuators are manufactured as follows.
1. Preparation of Tube A cylindrical single-layer tube having a length of 300 mm is prepared by processing the obtained rubber composition with an extrusion molding machine.

2. Fabrication of sleeve Two 2200 dtex aramid fibers are used as a raw yarn, 12 times / 10 cm of undertwisting is performed, and further 12 times / 10 cm of overtwisting are performed to produce an aramid fiber cord having a diameter of 0.7 mm. A mesh-like sleeve made by braiding 64 aramid fiber cords is prepared. This sleeve is a mesh-like tubular body in which 64 aramid fiber cords are observed on the circumference in the cross section. Specifically, this sleeve has 32 aramid fiber cords arranged at equal intervals in parallel and spirally, and the 32 aramid fiber cords obliquely intersect with each other and arranged at equal intervals in parallel and spirally. The other 32 aramid fiber cords thus formed are alternately knitted into a mesh-like tubular body, and the angle of each cord with respect to the axial direction of the sleeve is 25 degrees.

3. Manufacture of Actuator An actuator having the structure shown in FIGS. 1 and 2 is manufactured using the tube and the mesh sleeve. The length between the sealing mechanism 200 and the sealing mechanism 300 is 250 mm. UF46 manufactured by Cosmo Super Epoch Co., Ltd. is used as the hydraulic oil for the tube incorporated in the actuator.

<Evaluation>
1. Tensile stress (M200)
The vulcanized rubber test piece was processed into a dumbbell-shaped No. 8 test piece, and based on JIS K 6251 (2017), the modulus tensile elastic modulus at 200% elongation at a measurement temperature of 25 ° C. was obtained.

2. Abrasion resistance With respect to the vulcanized rubber test piece, the amount of abrasion at a slip ratio of 60% at room temperature was measured using a Lambourn abrasion tester.
The reciprocal of the wear amount of the vulcanized rubber test piece of Example 2 was set as 100 and expressed as an index. The larger the index value, the smaller the amount of wear and the better the wear resistance.

3. Workability Regarding the prepared rubber composition, the Mooney viscometer (RPA manufactured by Monsanto Co., Ltd.) was used according to JIS-K6300-1: 2001, and the Mooney of the rubber composition was used under the condition of 130 ° C. using an L-type rotor. The viscosity [ML _{1 +} 4/130 ° C.] was measured.
The value of the Mooney viscosity of the rubber composition was indexed in each Example and Comparative Example with the value of Example 2 being 100, and evaluated according to the following criteria.
(Evaluation criteria)
◯: The index is 100 or more, the flowability of the rubber composition is good, and the workability is excellent.
X: The index is less than 100, the flowability of the rubber composition is poor, and the workability is not excellent.

As can be seen from Table 1, the rubber component of Comparative Example 1 containing 60% by mass or more of a diene rubber having a glass transition temperature of −85 ° C. or less, and the inclusion of the carbon black of the present invention in the rubber composition. The rubber composition of Comparative Example 3 in which the amount is not 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component is not excellent in abrasion resistance of the vulcanized rubber. Furthermore, the rubber composition of Comparative Example 3 has a high Mooney viscosity and is not excellent in workability.
On the other hand, it can be seen that the rubber compositions of the examples have excellent abrasion resistance of the vulcanized rubber.

10: Actuator 20: Connection part 100: Actuator body part 110: Tube 111: Inner layer 112: Outermost layer 120: Sleeve 200: Sealing mechanism 210: Sealing member 211: Body part 212: Collar part 213: Uneven part 214: Small diameter Part 215: Passage hole 220: Locking ring 230: Caulking member 231: Indentation 300: Sealing mechanism 400: Fitting 410: Passage hole D _AX : Axial direction D _R : Radial direction

Claims (10)

A rubber component containing a diene rubber having a glass transition temperature of −85 ° C. or lower in an amount of 60% by mass or more and less than 100% by mass;
Nitrogen adsorption specific surface area of 75~180m ² / g, and carbon black as a DBP oil absorption is 100~140cm ³ / 100g,
A vulcanization accelerator,
Including sulfur,
The content of the carbon black is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component, and the total amount of the vulcanization accelerator and the sulfur is 1.5 parts by mass with respect to 100 parts by mass of the rubber component. More than a section,
A rubber composition for an actuator, which has a vulcanized rubber property of having a modulus tensile elastic modulus of 4.5 MPa or more when stretched 200% at 25 ° C.   The rubber composition for an actuator according to claim 1, wherein the diene rubber is butadiene rubber.   The rubber composition for an actuator according to claim 1, wherein the rubber component contains natural rubber.   The actuator according to any one of claims 1 to 3, wherein a mass ratio (s / a ratio) between the sulfur content s and the vulcanization accelerator content a is 0.95 to 3.0. Rubber composition.   A vulcanized rubber for an actuator, which uses the rubber composition for an actuator according to any one of claims 1 to 4.   Actuator body composed of a tubular tube that expands and contracts due to liquid pressure or air pressure, and a sleeve that is a tubular structure in which cords oriented in a predetermined direction are woven and that covers the outer peripheral surface of the tube. An actuator using the vulcanized rubber for an actuator according to claim 5, further comprising:   The actuator according to claim 6, wherein the tube has a single layer structure.   The actuator according to claim 6 or 7, wherein the layer thickness of the tube is 1.0 to 15.0 mm.   The actuator according to claim 6, wherein the tube has a multilayer structure.   The actuator according to claim 9, wherein the vulcanized rubber for actuator according to claim 5 is used for an outermost layer of the tube.