JPH0464506B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a refrigerant transport hose, and particularly to a hose used for piping of an automobile's car cooler or air conditioner. [Prior Art] As a hose for transporting a refrigerant such as Freon gas, the hose shown in FIG. 2, for example, is known. This hose consists of an inner tube layer 1, a fiber reinforced layer 2, and an outer tube layer 3.
It has a three-layer structure, and the inner tube layer 1 is usually made of acrylonitrile-butadiene copolymer (NBR).
The fiber reinforcing layer 2 is made of polyester fiber, vinylon fiber, etc., and the outer tube layer 3 is made of chlorosulfonated polyethylene (CSM) or the like.
is ethylene-propylene-diene rubber (EPDM)
It is formed by. Reference numeral 15 denotes a spiking hole, which extends from the surface of the outer tube layer 3 to the fiber reinforced layer 2, and allows permeated Freon gas etc. from the inner tube layer 1 to escape to the outside and accumulates between each layer (when gas accumulates, the area swells and causes delamination) ). In this way, a hose that is entirely formed of a rubber layer except for the fiber reinforcement layer 2 is flexible and easy to pipe, has good sealing properties with fittings such as nipples, and maintains airtightness. It has the following advantages. However, rubber materials generally have gas permeability,
The above hose also has the disadvantage that gas leakage occurs when a low molecular weight gas such as Freon gas is used as the refrigerant. On the other hand, nylon 6, which has excellent gas impermeability,
There are also known hoses whose innermost layer is made of polyamide resin such as . As shown in Fig. 3, this hose is divided into two layers, the part corresponding to the inner tube layer 1 shown in Fig. 2, the inner layer being a resin layer 4 made of polyamide resin, and the outer layer being made of rubber such as NBR. The rubber layer 5 consists of: A fiber reinforcing layer 2 and an outer tube layer 3 are formed in this order on the outer periphery. In FIG. 3, 15 is a spiking hole. Since the innermost layer of this hose is made of polyamide resin such as nylon 6, which has excellent gas impermeability, gas does not pass therethrough even if it is a low molecular weight gas. However, due to the rigidity of the polyamide resin, the hose itself lacks flexibility, and the polyamide resin in the innermost layer is deteriorated by metal ions derived from the metal in the piping system. In order to prevent such metal ion deterioration of polyamide resin, the hose has an inner rubber layer formed on the inner peripheral surface of the resin layer 4 made of polyamide resin using rubber made of NBR, CSM, chlorinated polyethylene (CPE), etc. is proposed. In this way, the resin layer 4 made of polyamide resin
By forming an inner rubber layer on the inner periphery of the piping system, the inner rubber layer comes into contact with the metal of the piping system and the resin layer 4 does not come into contact with the resin layer 4, thereby preventing metal ion deterioration of the resin layer 4. However, since the inner rubber layer is not as gas-impermeable as the resin layer 4 made of polyamide resin, the refrigerant gas passes through it and remains at the interface between the inner rubber layer and the resin layer.
This causes problems such as delamination between the inner rubber layer and the resin layer and gas deterioration of the inner rubber layer. [Problems to be Solved by the Invention] As described above, all conventional hoses have advantages and disadvantages as hoses for transporting refrigerant, and the reality is that they are not of sufficient quality. This invention was made in view of the above circumstances, and it is an object of the present invention to provide a refrigerant transport hose that has excellent gas impermeability and sealing properties, and does not cause delamination between the inner gas layer and the resin layer. purpose. [Means for Solving the Problems] In order to achieve the above object, the refrigerant transport hose of the present invention includes an inner pipe layer, an outer pipe layer outside the inner pipe layer,
It has a fiber reinforced layer interposed between both layers, the inner tube layer has a multilayer structure, and the inner layer of the inner tube layer is made of halogenated rubber made by halogenating α-olefin-alkyl acrylate copolymer rubber, making it gas impermeable. A synthetic resin with high properties is used as a layer outside the inner layer and adjacent to the inner layer. [Function] That is, as a result of repeated research focused on improving the gas impermeability of the inner rubber layer that constitutes the innermost layer of the hose, the present inventors found that α-olefin
When the inner rubber layer is made of a halogenated rubber obtained by halogenating alkyl acrylate copolymer rubber, the inner rubber layer itself becomes highly gas impermeable, and delamination between the inner rubber layer and the resin layer can be prevented. Moreover, the present invention was achieved by discovering that the rubber elasticity of the rubber itself is not impaired, and the sealing properties against nipples and the like are sufficiently maintained. Next, this invention will be explained in detail. The refrigerant transport hose of the present invention has a configuration as shown in FIG. In the figure, reference numeral 10 denotes an inner rubber layer, which is made of halogenated rubber obtained by halogenating ethylene-ethyl acrylate copolymer rubber. 11 is an intermediate resin layer, 12 is an outer rubber layer, 1
3 is a fiber reinforced layer, 14 is an outer tube rubber layer, and 15 is a spiking hole from the outer tube rubber layer 14 to the fiber reinforced layer 13.
It extends to Inner rubber layer 10, intermediate resin layer 11 of this invention,
The outer rubber layer 12 corresponds to the inner tube rubber layer 1 shown in FIG. The inner rubber layer 10 is made of halogenated rubber obtained by halogenating α-olefin-alkyl acrylate copolymer rubber, and is rich in rubber elasticity and at the same time is rich in refrigerant gas impermeability. . The above α-olefin-
The alkyl acrylate copolymer rubber uses an olefin having 2 to 4 carbon atoms such as ethylene, propylene, butylene as an α-olefin component, and methyl acrylate,
It is manufactured by a conventionally known method using an alkyl acrylate having 1 to 4 carbon atoms such as ethyl acrylate, propyl acrylate, butyl acrylate. Increasing the number of carbon atoms above makes the copolymer more flexible, but at the same time impairs gas impermeability, which limits the carbon chain length. Moreover, the ratio of α-olefin and alkyl acrylate in that case is set within the range of 95/5 to 60/40 (molar ratio). Halogenation of such copolymer rubber is also carried out by conventionally known methods, and the halogen elements used at that time include chlorine,
Bromine etc. are used. When halogenating in this way, the above-mentioned elements are set to be contained in the resulting halogenated rubber in an amount of 20 to 60% by weight (hereinafter abbreviated as [%]). That is, if the content of halogen elements such as chlorine and bromine is below the above range, gas impermeability will be lacking,
On the contrary, if it exceeds the above range, the rubber elasticity tends to be impaired. The intermediate resin layer 11 formed around the outer periphery of the inner rubber layer 10 has considerably more rigidity than a rubber material, and has the role of blocking the permeation of low molecular weight gases. Furthermore, if the fiber reinforced layer 13 is directly formed on the surface of the intermediate resin layer 11, the outer rubber layer 12 formed on the outer periphery of the intermediate resin layer 11 will lack elasticity, making it difficult to bend the refrigerant transport hose. This is formed in view of the fact that the inner surface of the hose will kink (buckle) and will not recover when the intermediate resin layer 1
It has the role of elastically supporting 1. The outer rubber layer 12 is made of a rubber material that is used in ordinary refrigerant transport hoses. Examples of the above-mentioned rubber materials include acrylonitrile-butadiene copolymer (NBR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CPE), epichlorohydrin rubber (CHC),
Chloroprene rubber (CR), chlorinated butyl rubber (Cl
-IIR), ethylene-propylene-diene rubber (EPDM), etc. The intermediate resin layer 11 sandwiched between the inner rubber layer 10 and the outer rubber layer 12 is made of polyamide resin such as nylon 6, ethylene-vinyl acetate, etc. from the viewpoint of gas impermeability and the presence or absence of a softening effect due to moisture absorption. It is preferable to use a saponified copolymer, a vinyl chloride-vinylidene chloride copolymer, or the like. The fiber reinforcing layer 13 may be one that is used in ordinary hoses, and may be made by braiding synthetic fibers such as polyester fibers and aramid fibers, or by braiding or spiral knitting yarns mainly made of natural fibers such as cotton fibers. It is formed. The outer tube rubber layer 14 is a layer exposed to the outside, and from the viewpoint of weather resistance, heat resistance, and water permeability,
Preferably, EPDM is used. However, there is no problem in using other rubber materials. The refrigerant transport hose of the present invention can be manufactured by laminating the above-mentioned layers, for example, in the following manner. (1) An unvulcanized rubber composition for forming the inner rubber layer 10 is extruded onto a rubber mandrel from an extrusion molding machine to obtain a tubular body. (2) Next, a resin adhesive dissolved in a solvent is applied to the outer circumferential surface of the tube, and then heated molten resin for forming the intermediate resin layer 11 is extruded onto it and cooled. (3) After applying a resin adhesive dissolved in a solvent to the outer peripheral surface of the intermediate resin layer 11, a rubber composition for forming the outer rubber layer 12 is extruded thereon to obtain a three-layer structure tube. (4) After applying rubber glue to the outer circumferential surface of the outer rubber layer 12 (unvulcanized), the yarn for the fiber reinforcement layer 13 is braided or the like to form the fiber reinforcement layer 13. (5) After applying rubber glue to the outer peripheral surface of the fiber reinforcing layer 13, a rubber composition for forming the outer tube rubber layer 14 is extruded onto it. (6) After vulcanizing and bonding the laminated tubes to integrate them, remove the mandrel. The vulcanization conditions are as follows:
Usually, the temperature is set at 145-170℃ and the time is set at 30-90 minutes. In the above manufacturing method, the thickness of the inner rubber layer 10 is
It is set to about 0.1 to 1.5 mm, preferably about 0.3 to 1.0 mm. That is, if the thickness is too thin, the sealing performance will be poor, and if it is too thick, the diameter of the inner rubber layer 10 will increase, so the diameter of the intermediate resin layer 11 formed on the outer periphery will also increase, and the resin itself of the intermediate resin layer 11 will become larger. This is because the resin layer 11 acts as bending resistance due to its increased rigidity, impairing the flexibility of the refrigerant transport hose of the present invention. The thickness of the intermediate resin layer 11 itself is 0.05 to 0.5 mm,
In particular, it is suitable to set it to about 0.1 to 0.3 mm. That is, if it is too thin, gas will easily pass through it, and if it is too thick, the rigidity will increase and the flexibility of the hose itself will deteriorate. Furthermore, the thickness of the outer rubber layer 12 needs to be set to be thick enough to reduce the kink property caused by the intermediate resin layer 11 and the fiber reinforced layer 13, and is set to a thickness of 1 to 3.
mm, preferably about 1.5 to 2.5 mm. Further, the thickness of the outer tube rubber layer 14 is 1.0 to 2.5 mm,
It is preferably about 1.2 to 2.0 mm. That is,
In order to improve water permeability, it is preferable to increase the wall thickness, but if the wall thickness is made too thick, it becomes difficult to use. Therefore, the outer tube rubber layer 14
The thickness is preferably within the above range. In the above embodiment, the outer rubber layer 12 is formed on the outer periphery of the resin layer, but depending on the case, this outer rubber layer 12 may be omitted. The refrigerant transport hose obtained in this way is
The resin layer, which has excellent gas impermeability, is not exposed directly to the inside and is protected by the inner rubber layer, so there is no risk of deterioration due to metal ions, etc. Furthermore, since the inner rubber layer itself has excellent gas impermeability, a situation in which refrigerant gas permeates through the inner rubber layer and stagnates at the interface between the inner rubber layer and the resin layer does not occur. Therefore, there is no delamination caused by refrigerant gas.
Furthermore, the inner rubber layer has rubber elasticity and tightly adheres to metal joints such as nipples, so it also exhibits excellent sealing properties. [Effects of the Invention] As described above, the refrigerant transport hose of the present invention maintains sufficient gas impermeability and has excellent sealing properties. Moreover, since the inner layer of the inner tube layer itself is highly impermeable to refrigerant gas, a situation in which refrigerant gas permeates through the inner layer and remains at the interface between the inner layer and the resin layer does not occur. Therefore,
It has a long life and is ideal for car cooler and air conditioner hoses that require sealing performance and gas impermeability over a long period of time. Next, examples will be described together with comparative examples. Examples 1 to 6, Comparative Examples 1 and 2 First, 90 mol% ethylene, ethyl acrylate
Ethylene-ethyl acrylate copolymer rubber was produced by charging raw materials at a ratio of 10 mol % and reacting them by a conventionally known method. Furthermore, a chlorinated rubber of ethylene-ethyl acrylate copolymer having a chlorine content of 40% was produced by reacting with chlorine using a known method. A halogenated rubber composition was prepared by blending the copolymer rubber (polymer) thus obtained and other raw materials as shown below. (Halogenated rubber composition) Polymer ethylene 90 mol% Ethyl acrylate 10 mol% 100 parts by weight MgO 5 Stearic acid 1 Vulcanizing agent Triazine 3 Next, butylene-ethyl acrylate copolymer and ethylene-butyl acrylate were prepared in the same manner. A halogenated rubber composition as described above was obtained by producing a copolymer chlorinated rubber, and using this and the materials shown in Table 1 below, Example products and A comparative hose was created.

【table】

[Table] A peel test of the inner rubber layer 10 was performed on each of the hoses thus obtained. The results are shown in Table 2 below. The evaluation was carried out in the following manner. <High-temperature unsealing peel test after permeation of refrigerant> Freon 12 (R-12) is sealed in a hose, both ends are sealed, and the hose is left at a temperature of 80 to 100°C for 168 hours, and then degassed. The pressure inside the hose is suddenly reduced due to this gas release, so if there is a peeled part in the inner rubber layer, that part will swell inward due to the sudden pressure reduction. The presence or absence of this swelling was visually inspected and evaluated. <Peeling Test on Actual Equipment Operation Test> After the hose was assembled into a refrigeration cycle device and operated continuously for 300 hours, 600 hours, and 700 hours, the presence or absence of blisters due to peeling of the inner rubber layer inside the hose was examined.

[Table] *1: Gas accumulates at the interface and peels off.
*○: No peeling.
From the above results, it can be seen that in all of the example products, the inner rubber layer did not peel off and was firmly attached to the resin layer on the outer peripheral surface.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing the structure of this invention, Fig. 2
The figure is a longitudinal sectional view showing a conventional product, and FIG. 3 is a longitudinal sectional view showing another conventional product. 1... Inner tube rubber layer, 10... Inner rubber layer, 11
...Intermediate resin layer, 12...Outer rubber layer, 13...
Fiber reinforcement layer, 14...outer tube rubber layer.

Claims (1)

[Claims] 1 Halogenated rubber comprising an inner tube layer, an outer tube layer outside the inner tube layer, and a fiber reinforcing layer interposed between both layers, the inner tube layer has a multilayer structure, and is made by halogenating α-olefin-alkyl acrylate copolymer rubber. A hose for transporting a refrigerant, characterized in that the inner layer of the inner pipe layer is made of a synthetic resin with high gas impermeability, and the layer outside the inner layer and adjacent to the inner layer is made of a synthetic resin with high gas impermeability. .