JPH11325330A - Hose for transporting coolant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably reduce permeation/leakage of carbon dioxide by forming a gas impermeable material layer by an organic material in which a coefficient of gas permeability for carbon dioxide at a specific temperature is a specified value, in a hose for transporting coolant which is provided with an internal pipe containing the gas impermeable material layer. SOLUTION: In a hose for transporting coolant 6, an internal pipe 3 constituted of a gas impermeable material layer 1 and an internal pipe elastomer layer 2 laminated on the layer 1 is coated with a reinforcing layer 4 and an external pipe 5. The gas impermeable material layer 1 is formed by an organic material in which a coefficient of gas permeability for carbon dioxide at 100 deg.C is 2×10<-10> cc. cm/cm Hg.cm<2> .sec or below. The gas impermeable material layer 1 is made of at least one polymer selected from among saponified ethylene-vinyl acetate copolymer (ethylene-vinylalcohol copolymers), copolymers of meta- xylylenediamine and adipic acid, polyvinylidene chloride, polyacrylonitrile and polyethylne 2,6-naphthalate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant transport hose suitable for transporting carbon dioxide gas as a refrigerant, for example, a hose for a vehicle cooler or an air conditioner piping.

[0002]

2. Description of the Related Art Conventionally, chlorofluorocarbon (CFC) or hydrochlorofluorocarbon (HCFC) has been used as a refrigerant gas for automotive coolers and air conditioners, and these fluorocarbon gases are transported. As a refrigerant transporting hose, a gas barrier inner layer containing a material having high CFC gas barrier properties, such as nitrile rubber, butyl rubber, or a mixture of polyamide resin and rubber, is provided inside the inner tube for the purpose of preventing CFC gas leakage. The arrangement is used.

[0003] However, these fluorocarbon gases contain chlorine in their structures, and are released into the atmosphere in small quantities during use of the refrigerant and in large quantities upon disposal of the refrigerant, reaching the stratosphere, causing photolysis, and There is a problem that chlorine atoms generated by the destruction of the ozone layer adversely affect the global environment.

[0004] Therefore, hydrofluorocarbon has been proposed as an alternative refrigerant to the above-mentioned chlorofluorocarbon gas, and since it does not contain chlorine atoms, it does not destroy the ozone layer.

However, the above-mentioned hydrofluorocarbons, chlorofluorocarbons, and hydrochlorofluorocarbons all have an extremely large infrared absorption capacity, exhibit a high greenhouse gas effect, and have a global warming potential several hundred to tens of thousands times higher than that of carbon dioxide. Global warming due to the release of these refrigerant gases into the atmosphere is of concern.

Under these circumstances, carbon dioxide, ammonia gas, LP
In recent years, materials that do not contain chlorine such as G and do not destroy the ozone layer and have a significantly lower global warming potential have been studied. Among them, carbon dioxide is most suitable as a refrigerant having various characteristics required for a refrigerant, such as having no adverse effect on the human body by suction or contact, having low flammability, and being chemically and physically stable. .

However, since carbon dioxide has a high solubility in resin and rubber and a very high gas permeability, the above-mentioned conventional refrigerant transport hose, that is, nitrile rubber, butyl rubber, or a mixture of polyamide resin and rubber is used. When a hose using a tube is used, there is a serious drawback in that the leakage of carbon dioxide is large, the refrigerant gas must be replenished frequently, and the tube is not practically used.

In order to prevent the leakage of carbon dioxide, carbon dioxide refrigerant is transported by using a refrigerant transport pipe formed of a metal pipe instead of the conventional refrigerant transport hose having a resin / rubber inner pipe. Although these metal pipes have been studied, these metal pipes may be loosened at the joints between the metal pipe and the directly connected equipment due to vibrations generated from equipment such as a compressor or other equipment (engine, etc.) directly connected. This causes a problem that carbon dioxide leaks out from the crack, and has not been put to practical use.

The present invention has been made in view of the above circumstances,
Refrigerant transport hose that significantly reduces carbon dioxide permeation and leakage, is flexible and absorbs vibrations generated from equipment, etc., and does not crack at the joints with equipment even if subjected to vibration The purpose is to provide.

[0010]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, in a hose for transporting carbon dioxide refrigerant, a specific gas impermeable material was used. By containing a layer in the inner tube, the leakage of carbon dioxide refrigerant is remarkably suppressed, and the vibration from peripheral devices is well absorbed. The present inventors have found that a hose for transporting a refrigerant can be obtained, and have accomplished the present invention.

That is, the present invention relates to a refrigerant transport hose provided with an inner tube containing a gas impermeable material layer, wherein the gas impermeable material layer has a gas permeability coefficient of 2 × for carbon dioxide at 100 ° C. 10 ^-10 cc. cm / cmH
g. cm ² . A hose for transporting a refrigerant, characterized by being formed of an organic material for less than or equal to sec.

In this case, in the present invention, it is possible to adopt a configuration in which the specific gas-impermeable material layer is provided on the inner tube, and the reinforcing layer and the outer tube are sequentially laminated on the outer side of the inner tube. In this case, the mechanical strength of the refrigerant transport hose is further improved,
This makes it possible to transport the refrigerant at a high pressure.

Hereinafter, the present invention will be described in more detail.

The refrigerant transport hose of the present invention has, for example, the structure shown in FIG. The refrigerant transport hose 6 includes an inner tube 3 composed of a gas-impermeable material layer 1 as an inner layer and an inner tube elastomer layer 2 as an outer layer laminated thereon. 5. The gas-impermeable material layer 1 may be formed as an outer layer, or the inner pipe 3 may have three or more layers, and the gas-impermeable material layer 1 may be an intermediate layer.

The gas-impermeable material layer 1 is heated at 100 ° C.
Gas permeability coefficient for carbon dioxide is 2 × 10^-Tenc
c. cm / cmHg. cm^Two. sec or less, preferably
1 × 10 ^-Tencc. cm / cmHg. cm^Two. less than sec
Lower, more preferably 7 × 10^-11cc. cm / cmH
g. cm^Two. It is composed of an organic material for less than sec. What
Note that such a gas permeability coefficient is based on JIS K 7126 “P
Gas permeability test method for plastic films and sheets "
It is a value measured according to. Gas for carbon dioxide
Permeability coefficient is 2 × 10^-Tencc. cm / cmHg. cm^Two.
sec, the usage conditions of the refrigerant transport system
And CO_TwoHoe whose main component is a large refrigerant gas
Out of the refrigerant transport system_TwoRelease
CO_TwoRefrigerant gas whose main component is
Needs to be replenished at the end of the period, reducing the practicality of the refrigerant system
I do.

As the organic material having the above gas permeability coefficient, any material having such a gas permeability coefficient may be used, but it is easy to process into a hose, flexibility after processing, vibration absorption, etc. Saponified ethylene-vinyl acetate copolymer (ethylene-vinyl alcohol copolymer (EVOH)), copolymer of meta-xylylenediamine and adipic acid (MXD6), polyvinylidene chloride And organic resins such as polyacrylonitrile and polyethylene 2,6-naphthalate. These can be used alone or in combination of two or more.

On the other hand, the material forming the inner tube elastomer layer 2 is not particularly limited, but those which do not impair the flexibility of the hose for transporting refrigerant of the present invention are suitable, and various resins and rubbers can be used. Among them, rubbers such as butyl rubber and acrylonitrile butadiene rubber, olefin copolymers,
Thermoplastic elastomers such as olefins, styrenes, polyamides, vinyl chlorides and fluorines are preferred.

When the gas-impermeable material layer 1 and the inner tube elastomer layer 2 are bonded to each other, an adhesive or an adhesive rubber may be used between them, or one or more layers of rubber, an ionomer resin, a thermoplastic elastomer may be used. Alternatively, the bonding can be strengthened through a layer of a thermoplastic resin. As the adhesive used here, any vulcanized adhesive commonly used for rubber, such as a chlorinated rubber-based adhesive, a hydrochloric acid-based rubber-based adhesive, a phenolic resin-based adhesive, and an isocyanate-based adhesive, can be used. . In addition, as an intermediate layer of rubber or the like,
IIR, Cl IIR, Br IIR, NBR, HNB
Rubbers such as R, EPDM, ACM, CR, FKM or resins such as olefins, polyamides, fluorine, and ionomers are suitable.

In the refrigerant transport hose of the present invention, a reinforcing layer 4 and an outer pipe 5 can be provided outside the inner pipe 3,
This further improves the mechanical strength of the hose.

The reinforcing layer 4 is provided outside the inner tube 3 and is made of a material which can withstand the pressure generated by the carbon dioxide medium flowing through the inner tube 3 in strength. Examples of the material having excellent pressure resistance used for the reinforcing layer 4 include various metal wires such as steel wire, copper wire, and aluminum wire, and organic fibers made of vinylon, polyester, nylon, and aramid. The reinforcing layer 4 is formed by winding or braiding a desired shape such as a spiral shape or a blade shape to a required thickness on the outer periphery of the tube 3. In addition,
The reinforcing layer 4 may be formed in multiple layers for the purpose of further improving the pressure resistance, and in this case, an intermediate layer of an adhesive, a resin, or the like can be provided.

The outer tube 5 is provided on the outside of the reinforcing layer 4 for the purpose of preventing the reinforcing layer 4 from scattering and enhancing the environmental resistance required depending on the installation location of the hose, such as weather resistance and heat resistance. Provided. The material constituting the outer tube 5 is preferably a material that meets this purpose and does not impair the flexibility of the entire hose, and examples thereof include resins and rubbers such as styrene-propylene rubber and thermoplastic elastomers.

There are no particular restrictions on the other construction of the hose for transporting refrigerant of the present invention. For example, an adhesive layer or another intermediate layer may be provided between the respective layers.

In the above refrigerant transport hose, the thickness of the gas impermeable material layer is preferably about 0.02 to 0.5 mm in consideration of the carbon dioxide refrigerant permeability and flexibility. When the inner tube elastomer layer is provided, the thickness is preferably about 0.2 to 5.0 mm from the viewpoint of workability and flexibility of the inner tube. Further, it is preferable that the outer tube has a thickness of about 0.5 to 3.0 mm from the viewpoint of a balance between strength and flexibility.

In the hose for transporting refrigerant of the present invention, for example, a gas-impermeable material layer is extruded into a tube shape, an adhesive is applied to the tube surface if necessary, and then an inner tube elastomer layer is formed on the outside of the resin tube. After forming an inner tube by extrusion coating, an organic fiber or the like is wound around the outer periphery of the inner tube to form a reinforcing layer, and the outer periphery of the reinforcing layer is further extruded and coated with a rubber composition to form an outer tube. It can be easily manufactured by arranging and vulcanizing the tube-shaped integrated material into a hose shape. The vulcanization conditions in this case can be 150 ° C. × 90 minutes.

[0025]

The refrigerant transport hose of the present invention has a temperature of 100 ° C.
Gas permeability coefficient for carbon dioxide at 2 × 10
^-10 cc. cm / cmHg. cm ² . Since the inner tube is formed using the gas impermeable material layer made of an organic material for less than or less than sec, it is possible to significantly suppress refrigerant leakage when carbon dioxide is transported as a refrigerant. The refrigerant transport hose of the present invention has sufficient mechanical strength, is excellent in weather resistance, absorbs vibration from peripheral devices well, and causes cracks in the hose joint even after long-term use. Long life without any. Therefore, the refrigerant transport hose of the present invention is extremely useful in transporting a carbon dioxide refrigerant having an extremely low global warming potential and without destroying the ozone layer.

[0026]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 As a saponified ethylene-vinyl acetate copolymer, an ethylene-vinyl alcohol copolymer (ethylene content 32 mol%, trade name "Epearl" manufactured by Kuraray, carbon dioxide permeability coefficient at 100 ° C. 1.2 ×
10 ^-11 cc. cm / cmHg. cm ² . sec) was extruded into a tube having an inner diameter of 7.0 mm and a thickness of 0.1 mm to produce a gas-impermeable material layer. On the other hand, butyl rubber is extruded into a tube having a thickness of 1.4 mm to produce an inner tube rubber layer, which is adhered and coated on the outer periphery of the gas-impermeable material layer tube via an adhesive to form an inner tube. did. A reinforcing layer was provided on the outer periphery of the inner tube rubber layer by coating a braided steel wire having a brass surface on one layer. The tubular material thus obtained is passed through an extruder,
A 1.5 mm-thick ethylene-propylene rubber was provided on the outermost periphery, and the entire tube was vulcanized at 150 ° C. for 90 minutes to form an outer tube, thereby obtaining a refrigerant transport hose of the present invention.

Example 2 An inner tube rubber layer (A) made of acrylonitrile-butadiene rubber, a polyacrylonitrile-based thermoplastic resin (trade name “Barex” manufactured by Mitsui Chemicals, Inc.)
4.2 × 10 ⁻¹¹ carbon dioxide permeability coefficient at 100 ° C.
cc. cm / cmHg. cm ² . sec), and a gas-impermeable material layer (B) made of butyl rubber and an inner tube rubber layer (C) made of butyl rubber are respectively extruded and formed into a tube shape, and these three tubes are formed of (A), (B) and (C). Laminated and bonded in order with an adhesive, inner diameter 7.0 mm, outer diameter 10.0 m
m inner tube was formed. The gas impermeable material layer (B)
Was 0.1 mm in thickness. Next, a reinforcing layer was provided on the outer periphery of the inner tube by coating a braid of a steel wire whose surface was brass-plated in two layers. At this time, a butyl rubber paint was applied and dried between the steel wire braided layers as an intermediate adhesive layer. The tube-like material thus obtained was passed through an extruder, and a 1.5 mm-thick ethylene-propylene rubber was provided on the outermost periphery of the extruder to make the entire tube 150 mm.
An outer tube was formed by vulcanizing at 90 ° C. × 90 minutes to obtain a refrigerant transport hose of the present invention.

[Comparative Example 1] Butyl rubber (carbon dioxide permeation coefficient at 100 ° C. 7.2 × 10 ⁻¹⁰ cc.cm/c)
mHg. cm ² . sec) with an inner diameter of 7.0 mm and an outer diameter of 1
It was molded into a tube of 0.0 mm to form a single-layer inner tube. On the outer periphery of the inner tube, a braided steel wire whose surface was brass-coated was coated in one layer to provide a reinforcing layer. The tube-like material thus obtained is passed through an extruder, and butyl rubber having a thickness of 1.5 mm is provided on the outermost periphery thereof,
The entire tube was vulcanized at 150 ° C. for 90 minutes to form an outer tube, and a transport hose was obtained.

Comparative Example 2 Nylon 6 (gas permeability coefficient at 100 ° C. 2.0 × 10 ⁻⁹ cc.cm/cmHg.
cm ² . sec) with an inner diameter of 7.0 mm and an outer diameter of 7.2 mm
Then, butyl rubber was molded into a tube having a thickness of 1.4 mm, and the two layers were laminated via an adhesive with the nylon layer on the inside to form an inner tube. On the outer periphery of the inner tube, a braided steel wire whose surface was brass-coated was coated in one layer to provide a reinforcing layer. The tubular material obtained in this manner was passed through an extruder, butyl rubber having a thickness of 1.5 mm was provided on the outermost periphery, and the entire tube was vulcanized at 150 ° C. for 90 minutes to form an outer tube. A transport hose was obtained.

[Evaluation] The gas barrier performance of the hoses for transporting refrigerant obtained in Examples and Comparative Examples was evaluated by a hose gas permeation test. In the hose gas permeation test, a test hose is filled with a carbon dioxide refrigerant at a rate of 0.61 g / m ³ and placed in a 100 ° C. atmosphere. Then, the weight after 24 hours and the weight after 96 hours were measured, and the weight difference was 100
C., the amount of refrigerant gas leakage for 72 hours. If the amount of leakage at this time is 10 g / m or more, the amount of leakage is so large that replenishment of the refrigerant must be carried out frequently, which is not practical.

As a result of the measurement, Example 1 was 4.0 g / m and Example 2 was 8.2 g / m. On the other hand, Comparative Example 1 was 20 g /
m and Comparative Example 2 were 80 g / m, the leakage amount was large, and they were not put to practical use.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas impermeable material layer 2 Inner tube elastomer layer 3 Inner tube 4 Reinforcement layer 5 Outer tube 6 Refrigerant transport hose

Claims (3)

[Claims] 1. A refrigerant transport hose having an inner tube containing a gas-impermeable material layer, wherein the gas-impermeable material layer has a gas permeability coefficient of 2 × 10 ⁻¹⁰ cc for carbon dioxide at 100 ° C. . cm / cmHg. cm ² . sec
A refrigerant transport hose formed of the following organic material. 2. The gas-impermeable material layer is selected from a saponified ethylene-vinyl acetate copolymer, a copolymer of meta-xylylenediamine and adipic acid, polyvinylidene chloride, polyacrylonitrile, and polyethylene 2,6-naphthalate. The refrigerant transport hose according to claim 1, wherein the hose is made of at least one polymer. 3. A refrigerant transport hose having an inner tube containing a gas-impermeable material layer, wherein a reinforcing layer and an outer tube are sequentially laminated on the outer periphery of the inner tube. Item 3. The hose for transporting refrigerant according to Item 1 or 2.