JP2005291281A - Hydraulic hose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic hose restricted in load to be applied to environment, and having high adhesiveness between layers and excellent durability. <P>SOLUTION: This hydraulic hose has an inner tube rubber layer, an outer cover rubber layer, and at least one reinforcing layer between the inner tube rubber layer and the outer cover rubber layer. At least one reinforcing layer is provided just under the outer cover rubber layer, and the outer cover rubber layer comprises a rubber component adjusted by polymerizing solution, a vulcanization accelerator and a dehydrating agent. Chlorine is not comprised in each of the layers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic hose such as a construction machine hydraulic hose or a civil engineering hydraulic hose.

  The structure of the hydraulic hose generally has an inner tube rubber layer, a reinforcing layer, and an outer rubber layer from the inside, and an intermediate rubber layer is appropriately provided between them. In such a hydraulic hose, a material mainly composed of chloroprene rubber (CR) is used in consideration of a balance of oil resistance, weather resistance, heat resistance, water resistance and the like.

  Since such a hydraulic hose contains chlorine, dioxins are generated by waste treatment (mainly incineration treatment), and the load on the environment is increased. Therefore, it is desirable to produce a hydraulic hose from a material that does not contain chlorine from the viewpoint of environmental protection. Moreover, since chlorine is not generated at the time of waste processing by not containing chlorine, deterioration of the incinerator can be prevented. Furthermore, if the waste treatment is environmentally friendly and efficient, the reinforcing wire used for the reinforcing layer of the hydraulic hose can be reused.

Therefore, a rubber hose that does not contain chlorine in materials such as an inner tube rubber layer and a jacket rubber layer has been proposed (see, for example, Patent Document 1).
However, since the rubber hose uses a reinforcing thread such as PET for the reinforcing layer, it is unclear whether it can be applied to a hydraulic hose that uses metal for the reinforcing layer.
In addition, in general hydraulic hoses, for example, there is a problem that high adhesion cannot be obtained between the metal reinforcement layer and the outer rubber layer, and the durability is improved by bonding each layer well. From the viewpoint of improvement, it has been clarified by the inventors that it is necessary to further study the composition of the outer rubber layer.
JP 2002-106756 A

This invention is made | formed in view of the said conventional problem, and makes it a subject to achieve the following objectives.
That is, an object of the present invention is to provide a hydraulic hose that has a low environmental load, high adhesion between layers, and excellent durability.

As a result of intensive studies to solve the above problems, the present inventor has found that the following problems can be solved by the present invention.
That is, the present invention is a hydraulic hose having an inner tube rubber layer and an outer rubber layer from the inside, and having at least one reinforcing layer between the inner tube rubber layer and the outer rubber layer,
At least one reinforcing layer is provided directly under the outer rubber layer;
The outer rubber layer contains a rubber component prepared by solution polymerization, a vulcanization accelerator, and a dehydrating agent,
The hydraulic hose is characterized in that each layer does not contain chlorine.

The hydraulic hose of the present invention preferably includes at least one of the following aspects (1) to (6).
(1) It is an embodiment in which the vulcanization accelerator is contained in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component of the outer rubber layer.
(2) It is an embodiment in which the outer rubber layer contains an organometallic acid salt.
(3) At least one intermediate rubber layer is further provided between the inner tube rubber layer and the outer cover rubber layer, and the one intermediate rubber layer is provided immediately above the inner tube rubber layer. And
At least, the rubber composition constituting the intermediate rubber layer provided immediately above the inner tube rubber layer contains a reinforcing filler, a non-reinforcing filler, and sulfur.
(4) The content of the non-reinforcing filler is 60 parts by mass or more with respect to 100 parts by mass of the rubber component, and the content of sulfur is 4 parts by mass or more with respect to 100 parts by mass of the rubber component. It is an aspect.
(5) It is an aspect in which the reinforcing layer is made of a metal linear material, and the linear material is spirally wound on the inner tube rubber layer.

  The hydraulic hose of the present invention has a low environmental load and high adhesion between layers. It is also excellent in durability.

  FIG. 1 shows a laminated structure example of a hydraulic hose according to an embodiment of the present invention. In the example of FIG. 1, the intermediate rubber layer 11, the reinforcing layer 13, the intermediate rubber layer 15, and the reinforcing layer 17 are sequentially formed on the inner tube rubber layer 10, and the outer rubber layer 18 is formed on the outer peripheral reinforcing layer 17. Is formed. Hereinafter, each layer will be described. In addition, each layer of the hydraulic hose of the present invention does not contain chlorine. Further, a thread layer may be formed between the inner tube rubber layer 10 and the intermediate rubber layer 11. The thread layer is provided to protect the inner tube rubber layer, and a material such as PET can be used.

[Coating rubber layer]
The outer rubber layer 18 contains a rubber component prepared by solution polymerization, a vulcanization accelerator, and a dehydrating agent.
By containing these, the adhesiveness between the outer rubber layer and the reinforcing layer can be greatly improved.

The influence of the residue can be eliminated by preparing the rubber component by a solution polymerization method. Here, the solution polymerization method refers to a method as described below. That is, first, butadiene, a solvent, and styrene are mixed with an adjusting device. As the solvent, an organic solvent capable of dissolving butadiene and styrene is used. Thereafter, the polymerization reaction is advanced in a polymerization apparatus, transferred to a coagulation apparatus, and coagulated using a coagulant. SBR (rubber component) is obtained by recovering the solvent and unreacted monomer with a solvent recovery device and then drying.
According to the solution polymerization method, since a residue during polymer polymerization, for example, a coagulant or an emulsifier is hardly generated, adhesion inhibition can be suppressed.
On the other hand, when producing a rubber component by an emulsion polymerization method, rosin acid, fatty acid, etc. resulting from the emulsifier may remain in the rubber component as a residue.

As the vulcanization accelerator, it is preferable to use thiuram in consideration of securing adhesion performance when a reinforcing layer (a linear object such as a wire) is formed by a steam vulcanization method.
As thiuram, tetramethyl thiuram monosulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide, dipentamethylene thiuram tetrasulfide and the like can be used. Moreover, you may use another promoter together as needed. The type of accelerator used in combination is not particularly limited.

  The content of the vulcanization accelerator is preferably 0.5 to 5 parts by mass and more preferably 2 to 3 parts by mass with respect to 100 parts by mass of the rubber component. By setting it as 0.5-5 mass parts, a vulcanization | cure speed | rate can be made into an appropriate range, and adhesiveness can be made favorable.

Moreover, the dehydrating agent can improve the adhesion failure resulting from moisture by removing moisture that enters during vulcanization. As the dehydrating agent, ZnO, CaO, MgO or the like can be used, and it is preferable to use ZnO. ZnO can further improve the effect of improving the adhesion failure by suppressing the dezincification reaction from the wire surface as the reinforcing layer by the dehydrating function.
The content of the dehydrating agent is preferably 1 to 20 parts by mass and more preferably 5 to 10 parts by mass with respect to 100 parts by mass of the rubber component. By setting it as 1-20 mass parts, the improvement effect of adhesion failure can be exhibited more reliably.

The outer rubber layer 18 mainly has a function of protecting the reinforcing layers 13 and 17 and is an environment in which a hydraulic hose is used such as light resistance, heat resistance, oil resistance, ozone crack resistance, flexibility and appearance performance. Select materials considering the above. In particular, select one that does not contain chlorine.
Specific examples of the rubber component include those containing no chlorine, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), ethylene propylene diene terpolymer (EPDM), butyl rubber (IIR), butadiene rubber (BR), styrene butadiene rubber (SBR), VAMAC (a copolymer of ethylene and methyl acrylate, in particular, a copolymer may be used) alone or appropriately blended.
In the present specification, the “rubber component” refers to a component made of the rubber as described above and serving as a base material for each layer.

The outer rubber layer 18 preferably contains various additives.
For example, by including an organic acid metal salt, the adhesiveness between the outer rubber layer 18 and the metal of the reinforcing layer 17 can be further enhanced by the catalytic action of the organic metal salt.
As the organic acid metal salt, an organic acid metal salt containing a transition metal, an organic acid metal salt containing aluminum or an alkali metal is preferable, and any one or more of Co, Zn, Ti, Mo, Zr, Al, and K is used. An organic acid metal salt contained is more preferable, and an organic acid metal salt containing at least Co is more preferable in consideration of improvement in adhesive strength and handleability.
In addition, the said organic acid metal salt may use multiple types together. Specific examples of the organic acid metal salt containing Co include cobalt naphthenate and cobalt stearate.

  The organic acid metal salt (all organic acid metal salts when used in combination) is preferably contained in an amount of 1 to 10 parts by weight, based on 100 parts by weight of the rubber component of the outer rubber layer 18, and 2 to 6 parts by weight. It is more preferable to contain part. By containing 1 to 10 parts by mass, good adhesiveness can be maintained.

If necessary, it is preferable to contain a vulcanization retarder (also referred to as a retarder). Examples of the vulcanization retarder include phthalic anhydride and phthalimide compounds.
In addition, carbon black (C / B), anti-aging agent, zinc white (ZnO), accelerators other than thiuram (DZ; manufactured by Ouchi Shinsei Chemical Co., Ltd.), and the like can be contained.

In particular, accelerators other than thiuram include N-tert-butyl-2-benzothiazolylsulfenamide (also referred to as “NS”), N, N′-dicyclohexyl-2-benzothiazolylsulfenamide (“DZ ), Sulfenamides such as N-cyclohexyl-2-benzothiazolylsulfenamide (also referred to as “CZ”), and thiazoles such as dibenzothiazyl disulfide (also referred to as “DM”). It is done.
The content of the slow-acting accelerator (the total content when a plurality of types are used in combination) is preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the rubber component of the jacket rubber layer 18. More preferably, the content is 5 to 1 part by mass. By containing 0.3 to 2 parts by mass, it is possible to achieve both the adhesion between the rubber and the reinforcing layer and the physical properties of the rubber.

  The thickness of the jacket rubber layer 18 is preferably in the range of 0.5 to 2.5 mm, more preferably in the range of 0.8 to 1.5 mm.

[Inner tube rubber layer]
The material of the inner tube rubber layer 10 is selected mainly in consideration of permeation resistance, and is preferably selected in consideration of moisture permeation resistance, heat resistance and flexibility. That is, it is preferable that the inner tube rubber layer 10 has a function of supporting internal pressure and preventing or reducing permeation of the oil-based fluid and intrusion of moisture from the outside.
As the material constituting the inner tube rubber layer 10, the same material as the outer rubber layer 20 can be appropriately selected and used in consideration of the above functions. In addition, compounding agents such as commonly used processing aids, antioxidants, vulcanizing agents, reinforcing agents, and vulcanization accelerators can be appropriately added to the above materials.
The thickness of the inner tube rubber layer 10 is preferably in the range of 1.0 to 2.0 mm, more preferably in the range of 1.5 to 1.8 mm.

[Reinforcement layer, intermediate rubber layer]
The reinforcing layers 13 and 17 have a two-layer structure in the illustrated embodiment, and the intermediate rubber layer 11 is provided between the inner tube rubber layer 10 and the reinforcing layer 13 and between the reinforcing layer 13 and the reinforcing layer 17. 15 are not limited to two layers, but may be a structure of three or more layers, or a structure of only one layer.

The reinforcing layers 13 and 17 are made of a metal linear object, and the linear object is provided by being wound on the inner tube rubber layer 10 (the intermediate rubber layer when an intermediate rubber layer is provided). It becomes.
Although it does not restrict | limit especially as a metal linear thing (reinforcement material) used for the reinforcement layers 13 and 17, Preferably, a metal wire, for example, the hard steel wire wire which gave the brass plating; Stainless steel wire; It is preferable to use known metal wires;
As described above, the reinforcing layers 13 and 17 may be formed of two or more layers. The number of layers is preferably determined appropriately according to the pressure of the liquid during use, that is, the internal pressure applied to the hose. Although there is no particular limitation on the configuration of the individual layers in the reinforcing layers 13 and 17 in this case, preferably, a configuration in which a metal wire is spirally wound (spiral configuration) as shown in the figure is exemplified. It can also be set as the structure (mesh structure: refer FIG. 2) etc. by which the metal wire was wound by mesh shape. The mesh configuration is mainly used for low pressure applications, and the helical configuration is mainly used for high pressure applications.

  The number of metal linear objects is preferably 8 to 60, more preferably 12 to 36, although it depends on the diameter of the hydraulic hose and the configuration of the reinforcing layer (helical, blade, etc.). Put on.

  Further, the intermediate rubber layers 11 and 17 have a function as a cushioning material that shows durability against the fluid that permeates the inner tube rubber layer 10 and prevents the reinforcing layers from being rubbed. As the rubber polymer constituting the intermediate rubber layers 11 and 17, hydrogenated NBR (HNBR), NBR, SBR, BR, natural rubber (NR), EPDM, and the like can be appropriately combined, and in some cases, can be used alone.

  At least in the rubber composition constituting the intermediate rubber layer 11 provided immediately above the inner tube rubber layer 10, “reinforcing filler, non-reinforcing filler, sulfur” or “reinforcing filler, non-reinforcing filler” It is preferable that a “reinforcing filler, peroxide” is contained. By containing these, while maintaining high adhesion to the reinforcing layer, it prevents bulging, prevents sulfur migration to the inner tube rubber layer 10 (low flow), and improves the durability of the hydraulic hose. Can be made.

  Here, “bulge” refers to a phenomenon in which the rubber appears to swell up near the crimping portion mouth of the connection fitting when used under high temperature conditions (about 100 ° C. or higher).

The bulge generating mechanism will be described with reference to FIGS. 3 to 5 showing a part of the end of the hydraulic hose.
First, at normal temperature, the crimping fitting 30 is attached to the end of the hydraulic hose and crimped (FIG. 3). By crimping, the inner tube rubber layer 10 and the intermediate rubber layer 11 are compressed, and the repulsive force acts in the longitudinal direction of the hydraulic hose (FIG. 4). However, at normal temperature, it is compressed by the adhesive force between the intermediate rubber layer 11 and the reinforcing layer (wire) 13, the physical properties of the intermediate rubber layer 11, and the adhesive force between the intermediate rubber layer 11 and the inner tube rubber layer 10 against the repulsive force. No volume movement occurs. That is, no bulge is generated.

However, if the crimped hydraulic hose is left in a high-temperature atmosphere, the intermediate rubber layer 11 and the inner tube rubber layer 10 expand, which increases the repulsive force. On the other hand, the adhesive force between the intermediate rubber layer 11 and the reinforcing layer 13 that has countered the repulsive force, the physical properties of the intermediate rubber layer 11, and the adhesive force between the intermediate rubber layer 11 and the inner tube rubber layer 10 are due to high temperature and compressive force. ,descend.
As a result, the compressed volume is released from the restraint of the crimping fitting 30, and volume movement occurs. However, the rubber of the hydraulic hose body part opposes the volume movement due to various physical properties and frictional forces. The intermediate rubber layer 11 and the inner rubber layer 10 sandwiched between the two forces are destroyed by the adhesive interface with the reinforcing layer 13 or the intermediate rubber layer 11 itself, and the binding force (adhesive force) to the reinforcing layer 13 is lost. The force is released by generating a bulge at the base of the metal fitting (FIG. 5).

  As described above, when a bulge is generated, fluid easily leaks out from the bulge portion and must be replaced immediately. However, at least the intermediate rubber layer 11 contains the above-described materials, so that the occurrence of bulge can be prevented and the durability of the hydraulic hose can be improved.

The reinforcing filler contributes to the realization of low flow properties mainly through the interaction between the functional group on the filler surface and the polymer.
As the reinforcing filler, it is preferable to use carbon black, silica or the like, and it is more preferable to use carbon black. The content of the reinforcing filler is preferably 20 to 80 parts by mass, and more preferably 40 to 60 parts by mass with respect to 100 parts by mass of the rubber component of the intermediate rubber layer. By setting it as 20-80 mass parts, the rubber hardness after vulcanization (the said rubber hardness contributes to fatigue resistance) and suppression and balance of flow property can be taken.

Non-reinforcing fillers contribute to the realization of low flowability and low setability mainly by the action of calcium carbonate, talc, mica and clay.
As the non-reinforcing filler, it is more preferable to use calcium carbonate.
The content of the non-reinforcing filler is preferably 60 parts by mass or more, more preferably 60 to 200 parts by mass, and more preferably 60 to 120 parts by mass with respect to 100 parts by mass of the rubber component of the intermediate rubber layer. More preferably. By setting it as 60 mass parts or more, low flow property can be improved, maintaining durability of a hydraulic hose favorably.

During vulcanization, sulfur easily migrates from the intermediate rubber layer 11 to the inner tube rubber layer 10, and the sulfur in the intermediate rubber layer 11 decreases, which may cause poor adhesion. Therefore, by including a large amount of sulfur in the intermediate rubber layer 11, even if sulfur shifts from the intermediate rubber layer 11 to the inner tube rubber layer 10, it is possible to suppress poor adhesion due to insufficient sulfur.
The sulfur content is preferably 4 parts by mass or more, more preferably 4 to 10 parts by mass, and more preferably 4 to 6 parts by mass with respect to 100 parts by mass of the rubber component of the intermediate rubber layer 11. Further preferred. By setting it to 4 parts by mass or more, even if sulfur shifts to the inner tube rubber layer, it becomes possible to ensure the physical properties of sulfur in the intermediate rubber layer 11, and more reliably suppress poor adhesion due to lack of sulfur. be able to.

  Moreover, you may contain a peroxide instead of sulfur. The peroxide is applied when a rubber component such as a fully hydrogenated HNBR or a certain kind of VAMAC (for example, D type) that hardly remains is used as the rubber component of the intermediate rubber layer. Partially hydrogenated HNBR and the like can be sulfur vulcanized because double bonds remain, whereas the rubber component cannot be sulfur vulcanized because almost no double bonds remain. It becomes possible to crosslink.

Here, the peroxide is a peroxide of an organic compound, for example, at least ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, etc. One type can be used.
In consideration of practicality, at least one kind of hydroperoxide such as t-butyl hydroperoxide and cumene hydroperoxide; dialkyl peroxide such as di-t-butyl peroxide and dicumyl peroxide; preferable.
In order to avoid the lack of physical properties, the peroxide is preferably contained in an amount of 2 to 8 parts by mass, more preferably 4 to 6 parts by mass with respect to 100 parts by mass of the rubber component of the intermediate rubber layer 11.

A hydraulic hose formed by laminating an inner tube rubber layer, an intermediate rubber layer, a reinforcing layer, and a jacket rubber layer can be manufactured in accordance with common usage.
In particular, the wire spiral hose (hose in which the wire of the reinforcing layer is wound spirally: a spiral configuration) is the final vulcanization, steam that is vulcanized with 140-160 ° C steam while covering the whole with cloth It is preferable to perform vulcanization.
In addition, the wire blade hose (hose in which the wire of the reinforcing layer is entangled and wound around in a mesh shape: mesh structure) is the final vulcanization and is heated by blowing hot air at 130 to 150 ° C while being covered with resin. It is preferable to perform hot air vulcanization.
Furthermore, it is preferable to perform a salt bath vulcanization in which the lean reinforcement first hose (Reinforcement First Hose) is vulcanized in a molten salt at 170 to 190 ° C. in the final vulcanization. It should be noted that since only the inner tube rubber heated to a temperature of about 90 ° C. is extruded, it loses its shape, and in order to prevent this, it is preferable to extrude it on a rod-like material called a mandrel, and to pulverize it after vulcanization.

As a configuration example of the wire blade hose, the one shown in FIG. 2 can be exemplified. That is, the reinforcing layer 12, the intermediate rubber layer 14, and the reinforcing layer 16 are sequentially formed on the inner tube rubber layer 10, and the outer rubber layer 18 is formed on the outer peripheral reinforcing layer 16.
In such a configuration, the outer rubber layer 18 preferably contains an internal adhesive.
In general, when water in the rubber composition disappears due to the inclusion of an antifoaming agent or the like, adhesion failure occurs between the outer rubber layer and the reinforcing layer. However, a high adhesive effect can be exhibited by including an internally added adhesive in the outer rubber layer 18 and vulcanizing at a predetermined temperature. This is thought to be due to a structure that can interact with both copper and polymer on the surface of the sulfided wire.

The internally added adhesive is a maleic anhydride modified product of a polymer chain having a double bond, and is preferably a polybutadiene modified with maleic anhydride. Specifically, Ricobond (RicoBond, manufactured by SARTOMER), Ricon (Ricon, manufactured by SARTOMER), and the like can be preferably used.
The internally added adhesive is preferably contained in an amount of 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component of the outer rubber layer 18. By containing 1 to 10 parts by mass, a high adhesion effect can be exhibited without causing vulcanization inhibition.

  As described above, the hydraulic hose of the present invention does not use any chlorine-containing rubber polymer that generates dioxin at the time of disposal or incineration. Therefore, the load on the environment is small, and components other than the wire can be incinerated, and the remaining wire can be reused as iron scrap.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

[Example 1]
An intermediate rubber layer is formed on the outer peripheral surface of a cylindrical inner tube rubber (thickness: 1.5 mm) made of a compound (compound) based on NBR, and the wire (material: core wire is iron, plating is brass ( A reinforcing layer (thickness: 0.3 mm) was formed by spirally winding copper and zinc)). Thereafter, an intermediate rubber layer (thickness: 0.3 mm) and a reinforcing layer (spiral, thickness: 0.3 mm) were sequentially formed.

On the outer peripheral reinforcing layer, 35 parts by mass of EPDM and 65 parts by mass of SBR prepared by solution polymerization were used as rubber components, and an outer rubber containing the additives shown in Table 1 below was extruded to form an outer rubber layer. Formed.
Thereafter, the whole is covered with a cloth, and steam is blown at 140 ° C. to 150 ° C. to perform vulcanization, and as shown in FIG. 1, the inner tube rubber layer, intermediate rubber layer, reinforcing layer, intermediate rubber layer, reinforcing A hydraulic hose having a layer and a jacket rubber layer in order was produced.

The composition of the intermediate rubber layer is as follows.
(1) Rubber component: SBR: 30 parts by mass, NBR: 70 parts by mass (2) Carbon black: 40 parts by mass (based on 100 parts by mass of rubber component)
(3) Calcium carbonate: 100 parts by mass (based on 100 parts by mass of rubber component)
(4) Cobalt naphthenate: 3 parts by mass (based on 100 parts by mass of rubber component)
(5) 6 parts by mass of sulfur (with respect to 100 parts by mass of the rubber component. However, in the case of an intermediate rubber layer between the reinforcing layer and 3 parts by mass)

(Peeling test)
The peeling test was conducted as described below.
First, as shown in FIG. 6, a set of seven wires 102 was attached to a mold (die) 100 for producing a slab sheet, and three sets of these were attached. Next, an unvulcanized rubber (thickness: 2 mm) 104 having the same composition as that of the outer rubber layer is rolled so as to have the same size as the mold 100, and affixed as shown in FIG. It was put on the attached wire 102. In the state of covering, the mold 100 was put into a vulcanizing press and vulcanized to produce a composite of the rubber 105 and the wire 102. The vulcanization conditions were 1.5 best (1 best was T90 (minute) in Curast).
After the vulcanization is completed, the composite of the rubber 105 and the wire 102 is taken out, and the wires at both ends of the seven wires in one set are bent as shown in FIGS. The book wire was pulled off by hand. As shown in FIG. 8, out of the surface area (Sw) of the five wires peeled off, the area (Sr) where the rubber is adhered is measured, and the area ratio (Sr / Sw × 100 (%)) is calculated. Calculation was made to evaluate adhesion. The results are shown in Table 1 below.
Next, the presence / absence of bulge (bulge test) and durability test (impulse test) were performed on the hydraulic hoses of Examples and Comparative Examples.

(Bulge test)
The bulge test (especially the bulge test for the outer bulge) was performed as described below. First, both ends of the produced hydraulic hose are crimped with metal fittings and left at room temperature for 24 hours. Then, it heated to 80 degreeC hydraulic hose crimped in oven, and it heat-processed by hold | maintaining at 80 degreeC to 150 degreeC every 10 degreeC at each temperature for 1 hour.
After the heat treatment at each temperature, the inside of the hydraulic hose was observed from the clamped metal fitting, and it was confirmed whether or not a bulge was generated near the crimped portion. The case where no bulge occurred at each temperature was accepted (corresponding to “O” in the table), and the case where bulge occurred at any temperature was rejected (corresponding to “X” in the table). . The results are shown in Table 1 below.

(Impulse test)
The impulse test (fatigue resistance test) was performed as described below. First, as shown in FIG. 9, the produced hydraulic hose 202 was attached to an impulse tester (an ultra-high pressure impulse tester manufactured by Kabaya Kogyo Co., Ltd.) via a crimping fitting 204. Under the following test conditions, the fluid was circulated in the direction of the arrow, and then the hydraulic hose 202 to which the crimping bracket 204 was attached was removed. The removed hydraulic hose 202 was dissected, and (1) the state of the crimped portion, (2) the presence or absence of breakage of the wire constituting the reinforcing layer of the hydraulic hose, and (3) the state of the rubber being cut were confirmed. After confirming the above conditions, if there is no problem such as oil leakage, hose disconnection, hose burst, etc., pass (corresponding to “O” in the table), and any decrease has occurred, there is a problem in practical use In some cases, the test was rejected (corresponding to “x” in the table). The results are shown in Table 1 below.

Impulse test conditions:
Fluid: IRM903.
Number of impacts: 1 million times.
Hydraulic pressure: 18 MPa.
Oil temperature ... 100 ° C.

[Examples 2 to 6 and Comparative Example 1]
A hydraulic hose was produced in the same manner as in Example 1 except that the composition of the outer rubber layer was changed to the composition shown in Table 1 below. Further, in the same manner as in Example 1, a peeling test, a bulge test, and an impulse test were performed. The results are shown in Table 1 below.

From Table 1, it was confirmed that no bulge occurred in any of the hydraulic hoses of the examples, and all the impulse tests passed, the adhesion between the layers was good, and the durability was excellent.
In addition, since the hydraulic hose of the example does not contain chlorine in the rubber composition, when treating waste, the load on the environment is small, and the wire can be reused as iron scrap. It is also significant from the viewpoint.

It is a perspective view which shows the laminated structure of the hydraulic hose which concerns on one Embodiment of this invention. It is a perspective view which shows the laminated structure of the hydraulic hose which concerns on other embodiment of this invention. It is explanatory drawing which shows the partial cross section of the edge part of the hydraulic hose for demonstrating the generation mechanism of a bulge. It is explanatory drawing which shows the partial cross section of the edge part of the hydraulic hose for demonstrating the generation mechanism of a bulge. It is explanatory drawing which shows the partial cross section of the edge part of the hydraulic hose for demonstrating the generation mechanism of a bulge. It is explanatory drawing for demonstrating the method of a peeling test. It is explanatory drawing for demonstrating the method of a peeling test. It is explanatory drawing for demonstrating the state of rubber adhesion in a peeling test. It is explanatory drawing for demonstrating the method of an impulse test.

Explanation of symbols

10 ... Inner tube rubber layers 12, 13, 16, 17 ... Reinforcing layers 11, 14, 15 ... Intermediate rubber layer 18 ... Outer rubber layer

Claims (6)

A hydraulic hose having an inner tube rubber layer and an outer rubber layer, and having at least one reinforcing layer between the inner tube rubber layer and the outer rubber layer,
At least one reinforcing layer is provided directly under the outer rubber layer;
The outer rubber layer contains a rubber component prepared by solution polymerization, a vulcanization accelerator, and a dehydrating agent,
A hydraulic hose characterized by not containing chlorine in each layer.   The hydraulic hose according to claim 1, wherein the vulcanization accelerator is contained in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component of the outer rubber layer.   The hydraulic hose according to claim 1 or 2, wherein the outer rubber layer contains an organometallic acid salt. At least one intermediate rubber layer is further provided between the inner tube rubber layer and the outer cover rubber layer, and the one intermediate rubber layer is adjacent to the inner tube rubber layer,
The rubber composition constituting the intermediate rubber layer adjacent to the inner tube rubber layer contains a reinforcing filler, a non-reinforcing filler, and peroxide or sulfur. Item 4. The hydraulic hose according to any one of Items 1 to 3.   The content of the non-reinforcing filler is 60 parts by mass or more with respect to 100 parts by mass of the rubber component, and the content of sulfur is 4 parts by mass or more with respect to 100 parts by mass of the rubber component. The hydraulic hose according to claim 4.   The said reinforcement layer consists of a metal linear thing, and the said linear thing is provided by being wound spirally on the said inner tube | pipe rubber layer, The any one of Claims 1-5 characterized by the above-mentioned. Hydraulic hose according to item.

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