Multilayered rubber hose and method for manufacturing the same

Abstract

The present invention provides a multi-layer hose that can suppress delamination while ensuring resistance to refrigerant permeation and POE (Polyoxyl Enzyme) emissions, and a method for manufacturing the same. [Solution] The inner rubber multilayer hose 1 comprises an inner rubber layer 11, an intermediate resin layer 12, an intermediate rubber layer 13, a fiber reinforcement layer 14, and an outer rubber layer 15, in that order from the inside. The intermediate resin layer 12 contains polyamide resin, and the inner rubber layer 11 has a first layer 11a containing ethylene propylene rubber and a second layer 11b containing butyl rubber, the second layer 11b being located outside the first layer 11a.

Description

Technical Field

[0001] The present invention relates to an inner rubber multi-layer hose and a method for manufacturing the same.

Background Art

[0002] There is a multi-layer hose used for transporting the refrigerant of a car air conditioner or the like. In Patent Document 1, as a multi-layer hose, a composite flexible hose laminated in the order of the innermost layer, the intermediate rubber layer, the fiber reinforcing layer, and the outer rubber layer from the inside is disclosed. By including a polyamide resin in the innermost layer, gas barrier properties for suppressing the permeation of the refrigerant, that is, refrigerant permeation resistance, are ensured.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The patentee of Patent Document 1 also manufactures a multi-layer hose called a barrier hose in which a layer containing butyl rubber is further added inside the innermost layer containing a polyamide resin. In an eco-car such as a hybrid car, a compressor is installed as an air conditioning system, and a polyol ester (POE)-based lubricant may be used as the lubricant. Since butyl rubber has poor compatibility with a POE-based lubricant, when a POE-based lubricant is used, the butyl rubber in the innermost layer that comes into contact with the lubricant may swell, resulting in problems. On the other hand, ethylene propylene rubber is more excellent in POE resistance than butyl rubber.

[0005] To ensure POE resistance, it is conceivable to use ethylene propylene rubber instead of butyl rubber in the innermost layer. However, there is another problem: the ethylene propylene rubber layer and the polyamide resin layer have poor adhesive compatibility.

[0006] The object of the present invention is to provide a multi-layer hose that can suppress delamination while ensuring resistance to refrigerant permeation and POE (Polyoxyl Enzyme) emissions, and a method for manufacturing the same. [Means for solving the problem]

[0007] (1) The inner rubber multilayer hose disclosed herein comprises, in order from the inside out, an inner rubber layer, an intermediate resin layer, another intermediate rubber layer, a fiber reinforcement layer, and an outer rubber layer. The intermediate resin layer contains a polyamide resin, and the inner rubber layer has a first layer containing ethylene propylene rubber and a second layer containing butyl rubber, the second layer being disposed on the outside of the first layer.

[0008] In this configuration, refrigerant permeability resistance is ensured by the intermediate resin layer containing polyamide resin, and POE resistance is ensured by the first layer of the inner rubber layer containing ethylene propylene rubber.

[0009] A layer containing butyl rubber has better adhesion to a layer containing polyamide resin than a layer containing ethylene propylene rubber. In the above configuration, a second layer containing butyl rubber is interposed between the first layer containing ethylene propylene rubber and the intermediate resin layer containing polyamide resin. Since an intermediate resin layer containing polyamide resin, which has good adhesion to the second layer, is laminated on top of the second layer containing butyl rubber, delamination between the second layer and the intermediate resin layer can be suppressed.

[0010] Furthermore, layers made of rubber have good adhesive properties. With the above configuration, a second layer made of rubber is laminated on top of a first layer made of rubber, so delamination between the first and second layers can be suppressed.

[0011] (2) In the inner rubber multilayer hose of (1), the ethylene propylene rubber may be ethylene propylene diene rubber (EPDM), and the butyl rubber may be halogenated butyl rubber.

[0012] This configuration makes the material easier to vulcanize, improving adhesion and further suppressing delamination.

[0013] (3) A manufacturing method disclosed herein is a method for manufacturing an inner rubber multilayer hose according to (1) or (2), comprising: a continuous extrusion molding step of forming a hose intermediate having the inner rubber layer, the intermediate resin layer, and the intermediate rubber layer in order from the inside by extruding the inner rubber layer, the intermediate resin layer, and the intermediate rubber layer in a series of steps in succession; a braiding step of forming the fiber reinforcement layer by braiding reinforcing threads onto the outer surface of the hose intermediate; an extrusion molding step of forming a second hose intermediate by extruding the outer rubber layer onto the outer surface of the fiber reinforcement layer; and a vulcanization step of vulcanizing the second hose intermediate.

[0014] This configuration allows for the suppression of contamination by sequentially extruding the inner rubber layer, the intermediate resin layer, and the intermediate rubber layer in a single, continuous process. Contamination refers to the inclusion of foreign matter or impurities in the product or manufacturing process. By suppressing contamination, adhesion is improved, and delamination between layers can be prevented.

[0015] (4) In the method for manufacturing the inner rubber multilayer hose described in (3), the first layer and the second layer constituting the inner rubber layer may be extruded simultaneously in the continuous extrusion molding step.

[0016] This configuration allows for greater suppression of contamination during the extrusion molding of the inner rubber layer. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a multi-layer hose that can suppress delamination while ensuring resistance to refrigerant permeation and POE (Polyoxyl Enzyme) emissions, and a method for manufacturing the same.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic perspective view showing the configuration of the inner rubber multi-layer hose 1 according to an embodiment of the present invention. [Figure 2] It is a flowchart of the manufacturing method of the inner rubber multi-layer hose 1 shown in FIG. 1. [Figure 3] It is a schematic view showing the configuration of an extruder etc. used in the continuous extrusion molding process of the manufacturing method shown in FIG. 2. [Figure 4] It is a table showing the experimental results of the examples.

Modes for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0020] The inner rubber multi-layer hose 1 shown in FIG. 1 is a hose for transporting the refrigerant of an air conditioner. The inner rubber multi-layer hose 1 is suitable for an air conditioner for an automobile, but may also be used for other air conditioners etc.

[0021] As shown in FIG. 1, the inner rubber multi-layer hose 1 includes an inner rubber layer 11, an intermediate resin layer 12, an intermediate rubber layer 13, a fiber reinforcing layer 14, and an outer rubber layer 15 in order from the inside (innermost layer side). The inner rubber layer 11 includes an inner first layer 11a and an outer second layer 11b. The inner rubber layer 11 is obtained, for example, by extrusion molding etc. Specifically, the inner rubber layer 11 may be obtained by multi-layer extrusion molding in which the two layers of the first layer 11a and the second layer 11b are extruded simultaneously.

[0022] The first layer 11a is the innermost layer (innermost layer) of the inner rubber multilayer hose 1. The first layer 11a is directly exposed to the refrigerant and lubricating oil passing through the inner rubber multilayer hose 1. The lubricating oil is the lubricating oil for the compressor used to compress the refrigerant. Polyol ester (POE) based lubricating oil may be used as the lubricating oil. Other lubricating oils may also be used. The first layer 11a is a rubber layer containing ethylene propylene rubber that has oil resistance, and in particular, POE resistance. It is preferable to use ethylene propylene diene rubber (EPDM) as the ethylene propylene rubber. This allows for the selection of various vulcanizing agents depending on the conditions, without being limited to peroxide vulcanization, etc. However, it is not limited to this; for example, the ethylene propylene rubber may be ethylene propylene rubber (EPM). The first layer 11a may contain one type of ethylene propylene rubber, or it may contain two or more types of ethylene propylene rubber. Furthermore, the first layer 11a may contain materials other than ethylene propylene rubber. For example, the first layer 11a may contain rubber other than ethylene propylene rubber, fillers, processing aids, antioxidants, vulcanizing agents, vulcanization accelerators, etc. By using rubber containing propylene rubber in the first layer 11a, swelling of the inner rubber layer 11 due to lubricating oil can be suppressed.

[0023] The second layer 11b is provided on the outside of the first layer 11a. The second layer 11b is provided to improve the adhesion between the inner rubber layer 11 and the intermediate resin layer 12. The second layer 11b is a rubber layer containing butyl rubber. It is preferable to use halogenated butyl rubber (brominated butyl rubber (BIIR), chlorinated butyl rubber (CIIR), etc.) as the butyl rubber. This allows for co-vulcanization with the first layer 11a when ethylene propylene diene rubber is used as the first layer 11a, further improving the adhesion between the first layer 11a and the second layer 11b. However, it is not limited to this, and for example, the butyl rubber may be regular butyl rubber (IIR). The second layer 11b may contain one type of butyl rubber, or two or more types of butyl rubber. In addition, the second layer 11b may contain materials other than butyl rubber. For example, the second layer 11b may contain rubber other than butyl rubber, fillers, processing aids, antioxidants, vulcanizing agents, vulcanization accelerators, etc. Butyl rubber has better adhesion to the polyamide resin contained in the intermediate resin layer 12 than ethylene propylene rubber contained in the first layer 11a. Therefore, by providing a second layer 11b containing butyl rubber, the interlayer adhesion between the inner rubber layer 11 and the intermediate resin layer 12 can be improved. In addition, because butyl rubber has higher gas barrier properties than ethylene propylene rubber, the refrigerant permeability resistance of the inner rubber layer 11 can be improved.

[0024] The intermediate resin layer 12 is provided on the outside of the inner rubber layer 11. The intermediate resin layer 12 contains a polyamide resin. As the polyamide resin, for example, one of the following may be used: polyamide 6, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, polyamide 612, polyamide MXD6, and two or more copolymers thereof, or two or more may be mixed and used. The intermediate resin layer 12 may also contain components other than polyamide.

[0025] The intermediate rubber layer 13 is provided on the outside of the intermediate resin layer 12. The intermediate rubber layer 13 contains rubber. For example, butyl rubber may be used as the rubber contained in the intermediate rubber layer 13. The intermediate rubber layer 13 may contain one type of butyl rubber, or two or more types of butyl rubber. In addition, the intermediate rubber layer 13 may contain materials other than butyl rubber. For example, the intermediate rubber layer 13 may contain rubber other than butyl rubber, fillers, processing aids, antioxidants, vulcanizing agents, vulcanization accelerators, etc.

[0026] The fiber reinforcement layer 14 is provided on the outside of the intermediate rubber layer 13. The fiber reinforcement layer 14 is provided, for example, to improve pressure resistance against internal pressure from a compressor and to provide mechanical strength. The fiber reinforcement layer 14 is formed by winding reinforcing yarn around the intermediate rubber layer 13 and braiding it. The braiding method is not particularly limited and examples include spiral braiding and braiding. Examples of reinforcing yarns include polyethylene terephthalate, polyvinyl alcohol, polyester, polyamide, aramid, steel wire, and glass fiber.

[0027] The outer rubber layer 15 is provided on the outside of the fiber reinforcement layer 14. The outer rubber layer 15 contains rubber. For example, ethylene propylene rubber may be used as the rubber contained in the outer rubber layer 15. The outer rubber layer 15 may contain one type of ethylene propylene rubber, or it may contain two or more types of ethylene propylene rubber. In addition, the outer rubber layer 15 may contain materials other than ethylene propylene rubber. For example, the outer rubber layer 15 may contain rubber other than ethylene propylene rubber, fillers, processing aids, antioxidants, vulcanizing agents, vulcanization accelerators, etc.

[0028] The thickness of the inner rubber layer 11 (first layer 11a, second layer 11b), the thickness of the intermediate resin layer 12, the thickness of the intermediate rubber layer 13, the thickness of the fiber reinforcement layer 14, and the thickness of the outer rubber layer 15 are not particularly limited. Here, "thickness" refers to the dimensions of the radial cross-section of the inner rubber multi-layer hose 1.

[0029] (Manufacturing method) Next, an example of a manufacturing method for the inner rubber multi-layer hose 1 will be described.

[0030] As shown in Figure 2, the manufacturing method for the inner rubber multi-layer hose 1 comprises a continuous extrusion molding process (S1), a braiding process (S2), an extrusion molding process (S3), and a vulcanization process (S4). The continuous extrusion molding process (S1) is a process in which the inner rubber layer 11, the intermediate resin layer 12, and the intermediate rubber layer 13 are extruded sequentially in a series of steps. In the continuous extrusion molding process (S1), a hose intermediate body is formed which has the inner rubber layer 11, the intermediate resin layer 12, and the intermediate rubber layer 13 in that order from the inside.

[0031] In the example of the continuous extrusion molding process (S1) shown in Figure 3, continuous extrusion molding is performed using the first extruder 21, the second extruder 22, and the third extruder 23. The continuous extrusion molding process (S1) is a batch process that manufactures hose intermediates using the first extruder 21, the second extruder 22, and the third extruder 23.

[0032] The first extruder 21 is a multilayer extruder that simultaneously extrudes multiple different materials to form a single composite structure. For example, the first extruder 21 is configured to form a multilayer structure by concentrically stacking multiple different materials within a co-extrusion die. In this embodiment, using the first extruder 21, a material containing ethylene propylene rubber, which will become the first layer 11a, and a material containing butyl rubber, which will become the second layer 11b, are simultaneously extruded in a stacked state onto a mandrel coated with a release agent. By co-extruding the first layer 11a and the second layer 11b in this way, the interlayers of the inner rubber layer 11 are well bonded.

[0033] Then, the second extruder 22 extrudes the intermediate resin layer 12 onto the inner rubber layer 11 extruded by the first extruder 21. Then, the third extruder 23 extrudes the intermediate rubber layer 13 onto the intermediate resin layer 12 extruded by the second extruder 22. In this way, a hose intermediate body having the inner rubber layer 11, the intermediate resin layer 12, and the intermediate rubber layer 13 in that order from the inside out is formed in a batch process having a series of extrusion steps. By extruding the inner rubber layer 11, the intermediate resin layer 12, and the intermediate rubber layer 13 in that order in a single step, interlayer contamination can be suppressed. Also, because the extrusion steps are performed continuously, the material for the intermediate resin layer 12 is extruded onto the surface of the inner rubber layer 11 while the temperature of the inner rubber layer 11 is still high, and the material for the intermediate rubber layer 13 is extruded onto the surface of the intermediate resin layer 12 while the temperature of the intermediate resin layer 12 is still high. At higher temperatures, molecular mobility increases, leading to greater entanglement between layers, thus improving the interlayer adhesion of the hose intermediate.

[0034] The braiding process (S2) is a process in which a fiber reinforcement layer 14 is formed by braiding reinforcing threads onto the outer surface of the hose intermediate formed in the continuous extrusion molding process (S1) using a braiding machine (not shown). For example, an adhesive may or may not be used for braiding the reinforcing threads.

[0035] The extrusion molding process (S3) is a process in which an outer rubber layer 15 is formed on the fiber reinforcement layer 14 by extrusion molding to form a second intermediate hose. In the extrusion molding process (S3), rubber (for example, butyl rubber) is extruded onto the fiber reinforcement layer 14 using an extruder (not shown) to form the outer rubber layer 15. In other words, when the extrusion molding process (S3) is completed, a second intermediate hose is formed, which has an inner rubber layer 11, an intermediate resin layer 12, an intermediate rubber layer 13, a fiber reinforcement layer 14, and an outer rubber layer 15 in that order from the inside.

[0036] The vulcanization step (S4) is a step in which the second intermediate hose formed in the extrusion molding step (S3) is vulcanized. In the vulcanization step (S4), the inner rubber layer 11, the intermediate rubber layer 13, and the outer rubber layer 15 of the second intermediate hose are vulcanized. The vulcanization method is preferably, but not limited to, steam vulcanization. For example, the vulcanization method may be hot air vulcanization or the like.

[0037] Although embodiments of the present invention have been described above, these are merely illustrative examples and do not particularly limit the present invention. Specific configurations and other aspects can be modified as appropriate. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferred actions and effects resulting from the present invention, and the actions and effects according to the present invention are not limited to those described in the embodiments. [Examples]

[0038] Next, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0039] (Example 1) An inner rubber multilayer hose 1 was manufactured, comprising, in order from the inside out, an inner rubber layer 11, an intermediate resin layer 12, an intermediate rubber layer 13, a fiber reinforcement layer 14, and an outer rubber layer 15. The inner rubber layer 11 is composed of a first layer 11a containing ethylene propylene rubber and a second layer 11b containing butyl rubber. Ethylene propylene diene rubber (EPDM) was used as the first layer 11a of the inner rubber layer 11. Brominated butyl rubber (BIIR) was used as the second layer 11b of the inner rubber layer 11. The first layer 11a and the second layer 11b of the inner rubber layer 11 were obtained by simultaneously extruding them using a multilayer extruder. A polyamide resin was used as the intermediate resin layer 12. Brominated butyl rubber (BIIR) was used as the intermediate rubber layer 13. The fiber reinforcement layer 14 was formed by wrapping reinforcing yarn (PET fiber) made of polyethylene terephthalate around the intermediate rubber layer and knitting it using a braiding technique. Ethylene propylene diene rubber (EPDM) was used as the outer rubber layer 15. By laminating the material in this manner and vulcanizing it with steam, a multi-layered rubber hose 1 with an inner diameter of 15.9 mm, an outer diameter of 23.6 mm, and a wall thickness of 3.85 mm was manufactured.

[0040] (Comparative Example 1) Comparative Example 1 is as follows: An inner rubber single-layer hose was manufactured, comprising, from the inside out, an inner rubber layer, an intermediate resin layer, another intermediate rubber layer, a fiber reinforcement layer, and an outer rubber layer, in that order. The inner rubber layer is a single layer of ethylene propylene diene rubber (EPDM). A polyamide resin was used as the intermediate resin layer. Brominated butyl rubber (BIIR) was used as the intermediate rubber layer. The fiber reinforcement layer was formed by wrapping reinforcing threads (PET fibers) made of polyethylene terephthalate around the intermediate rubber layer and then braiding them together. Ethylene propylene diene rubber (EPDM) was used as the outer rubber layer. By laminating the material in this manner and vulcanizing it with steam, a single-layer inner rubber hose with an inner diameter of 15.9 mm, an outer diameter of 23.6 mm, and a wall thickness of 3.85 mm was produced.

[0041] The following experiments were conducted using Example 1 and Comparative Example 1 described above.

[0042] (Experiment 1: POE resistance test) The test specimens used in Experiment 1 were prepared by using the inner rubber (EPDM) from Example 1 and Comparative Example 1. They were vulcanized from an unvulcanized state of 2 mm thickness using a press, and then punched out to a size of 20 mm x 30 mm. These specimens were subjected to a POE resistance test by immersion in polyol ester (POE) heated to 100°C for 70 hours, in accordance with JIS K6258. Three specimens were tested for each example. The volume was measured before and after the test, and the volume change rate was calculated. The target value was for the volume change rate to fall within a range of plus or minus 5%.

[0043] As shown in Figure 4, the results of Experiment 1 showed that the volume change rate of all specimens in Example 1 was in the range of 0% to 1%, which falls within the target range. Thus, it was shown that the first layer 11a of the inner rubber layer 11 of Example 1 ensures POE resistance. In addition, the volume change rate of all specimens in Comparative Example 1 was also in the range of 0% to 1%.

[0044] (Experiment 2: Adhesion Test) The test specimens used in Experiment 2 were cut from Example 1 and Comparative Example 1, which were prepared as described above, into strips measuring 10 mm in width and 100 mm in length. For the test specimen of Example 1, an adhesion test was performed on the rubber layers of the inner rubber layer 11 (ethylene propylene rubber and butyl rubber) in accordance with JIS K6256-1. In addition, for the test specimen of Example 1, an adhesion test was performed on the second layer and the intermediate resin layer (butyl rubber and polyamide resin) of the inner rubber layer in accordance with JIS K6256-1. Furthermore, for the test specimen of Comparative Example 1, an adhesion test was performed on the inner rubber layer and the intermediate resin layer (ethylene propylene rubber and polyamide resin) in accordance with JIS K6256-1. Three test specimens were used for each test.

[0045] As shown in Figure 4, the results of Experiment 2 showed that in Comparative Example 1, the inner rubber layer (ethylene propylene rubber) and the intermediate resin layer (polyamide resin) delaminated at the interface. In Example 1, however, the rubber layers of the inner rubber layer 11 (ethylene propylene rubber and butyl rubber) did not delaminate from each other, but rubber cohesive failure occurred at the layer holding area. Also in Example 1, the second layer 11b and the intermediate resin layer 12 (butyl rubber and polyamide resin) of the inner rubber layer 11 did not delaminate, but rubber cohesive failure occurred at the layer holding area. Thus, in Example 1, rubber cohesive failure occurred before interface delamination, indicating good interfacial adhesion.

[0046] (Experiment 3: Refrigerant permeability) Refrigerant permeability tests were conducted in accordance with SAE J2064. SAE J2064 is a standard established by the SAE (Society of Automotive Engineers) concerning hoses and other components used in automotive air conditioning systems. From Example 1 and Comparative Example 1, which were prepared as described above, test samples with a hose length of 107 cm were used. HFO-1234yf (manufactured by Mitsui DuPont Fluorochemicals) was filled into these test samples to 70% of the hose's internal volume, and an internal pressure of 2.52 MPa was applied for 25 days at 80°C. Four test samples were used for each test. The decrease in the mass of the refrigerant in the test samples was measured, and the refrigerant permeability per unit surface area of ​​the inner surface of the hose was calculated. The target value for refrigerant permeability was 1.5 kg / m³. 2 It must be less than / year.

[0047] As shown in Figure 4, the results of Experiment 3 showed that the refrigerant permeability of all the test samples in Example 1 was 0.2-0.3 kg / m³. 2 The values ​​were found to be within the range of / year, and within the range of the target value. Thus, it was shown that the inner rubber multilayer hose 1 of Example 1 has the effect of suppressing refrigerant permeability. Furthermore, for all the test samples of Comparative Example 1, the refrigerant permeability was 0.2 to 0.3 kg / m³. 2 It was within the range of / year. [Explanation of Symbols]

[0048] 1: Multi-layered hose with inner rubber 11: Inner rubber layer 11a: 1st layer 11b: 2nd layer 12: Intermediate resin layer 13: Intermediate rubber layer 14: Fiber-reinforced layer 15: Outer rubber layer

Claims

1. It comprises an inner rubber layer, an intermediate resin layer, another intermediate rubber layer, a fiber reinforcement layer, and an outer rubber layer, in that order from the inside out. The aforementioned intermediate resin layer contains a polyamide resin. The inner rubber layer is A first layer containing ethylene propylene rubber, A second layer comprising butyl rubber, the second layer being disposed on the outside of the first layer, A multi-layered hose with an inner rubber construction.

2. In the inner rubber multilayer hose according to claim 1, The aforementioned ethylene propylene rubber is ethylene propylene diene rubber (EPDM), The butyl rubber is a halogenated butyl rubber. Multi-layered hose with inner rubber.

3. A method for manufacturing an inner rubber multilayer hose according to claim 1 or 2, A continuous extrusion molding process to form a hose intermediate having the inner rubber layer, the intermediate resin layer, and the intermediate rubber layer in order from the inside out, by extruding the inner rubber layer, the intermediate resin layer, and the intermediate rubber layer in a series of continuous steps, A braiding step in which reinforcing threads are braided onto the outer surface of the hose intermediate to form the fiber reinforcement layer, An extrusion molding step to form the outer rubber layer on the outer surface of the fiber reinforcement layer by extrusion molding to form a second intermediate hose, A vulcanization step for vulcanizing the second intermediate hose, A method for manufacturing a multi-layered hose with an inner rubber surface.

4. In the method for manufacturing an inner rubber multilayer hose according to claim 3, In the continuous extrusion molding process, the first layer and the second layer constituting the inner rubber layer are extruded simultaneously. A method for manufacturing a multi-layered hose with an inner rubber core.

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