DE102016013584A1 - Hose for conducting a refrigerant - Google Patents

Abstract

A hose for guiding a refrigerant which is excellent in refrigerant permeation resistance and heat resistance, and excellent in the resistance to extraction with a refrigerant or lubricating oil flowing in the hose is provided. The tube for conducting a refrigerant comprises: a tubular innermost layer (1) formed of a fluororesin, a polyamide resin layer (2) disposed so as to contact an outer circumferential surface of the innermost layer (1) a first rubber layer (3a) disposed so as to be in contact with an outer peripheral surface of the polyamide resin layer (2), a reinforcing layer (4) disposed so as to contact an outer circumferential surface of the first rubber layer (3a) and a second rubber layer (3b) disposed so as to be in contact with an outer peripheral surface of the reinforcing layer (4), the polyamide resin layer (2) being made of a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 or less is trained.

Description

TECHNICAL AREA

The present disclosure relates to a hose for conducting a refrigerant, which serves as a hose for conducting a refrigerant for a vehicle, such. As an automobile, is suitable.

STATE OF THE ART

In recent years, in the context of stricter regulations regarding the release of an ozone layer-depleting gas, the requirements for refrigerant barrier properties (refrigerant permeation resistance) of a hose for conducting a refrigerant to be used for an automobile or the like have become strict. Accordingly, z. For example, a resin having a high crystallinity, such as. As a polyamide resin, used as a formation material for an innermost layer of the tube for conducting a refrigerant.

DOCUMENT OF THE PRIOR ART

Patent Document

• PTL 1: JP 2002-181254 A

SUMMARY OF THE INVENTION

However, a polyamide resin has a problem that, particularly in a high-temperature environment, its oligomer component tends to be extracted with a refrigerant or lubricating oil flowing in a hose. The temperature of the inside of an engine compartment is high, and thus there is a tendency that such a problem as described above occurs. In addition, if such an oligomer component z. B. accumulates in a valve in a refrigerant pipe, a problem in that the flow of the refrigerant is interrupted.

The present disclosure has been made in view of these circumstances, and an object is to provide a hose for conducting a refrigerant having excellent refrigerant permeation resistance and heat resistance and having excellent resistance to extraction with a refrigerant or lubricating oil contained in the hose flows.

In order to achieve the above object, according to an embodiment of the present invention, there is provided a hose for conducting a refrigerant having the following structure: a hose for conducting a refrigerant, comprising: a tubular innermost layer formed of a fluororesin, a polyamide resin layer is disposed so as to be in contact with an outer peripheral surface of the innermost layer, a first rubber layer disposed so as to contact an outer peripheral surface of the polyamide resin layer, a reinforcing layer arranged to be connected to an outer peripheral surface of the polyamide resin layer first rubber layer in contact, and a second rubber layer which is arranged so that it is in contact with an outer peripheral surface of the reinforcing layer, wherein the polyamide resin layer of a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 o who is less educated.

That is, the inventors have made extensive investigations to solve the problems. In the course of the investigations, in order to obtain a tube having excellent heat resistance and refrigerant permeation resistance, the present inventors conducted investigation of the arrangement of a polyamide resin layer formed of a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 or less. However, when the polyamide resin layer is used as the innermost layer, there is a concern about extraction of an oligomer component with a refrigerant or a lubricating oil as described above, and thus the inventors made a study on the further arrangement of a fluororesin layer on the inner peripheral surface of the polyamide resin layer , Moreover, in order to improve the bending resistance, heat resistance, water resistance, strength and the like required for a hose for conducting a refrigerant, the inventors have studied on lamination of a first rubber layer, a reinforcing layer and a second rubber layer in FIG the above order on the outer peripheral surface of the polyamide resin layer. As a result, the inventors have found that the desired object can be achieved, and thus the resulting hose can have excellent performance as a hose for conducting a refrigerant, and thus have obtained the present disclosure.

According to the present disclosure, the tube for guiding a refrigerant may be provided, comprising: the tubular innermost layer formed of a fluorine resin, the polyamide resin layer disposed so as to contact an outer circumferential surface of the innermost layer, the first one A rubber layer disposed so as to be in contact with an outer peripheral surface of the polyamide resin layer, the reinforcing layer arranged to contact an outer circumferential surface of the first rubber layer, and the second rubber layer arranged to be is in contact with an outer peripheral surface of the reinforcing layer, wherein the polyamide resin layer is formed of a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 or less. Accordingly, the hose has excellent refrigerant permeation resistance and heat resistance, and has excellent resistance to extraction with a refrigerant or lubricating oil flowing in the hose. Therefore, the problem that an extract (the oligomer component of the polyamide resin) accumulates in a refrigerant piping so that the flow of the refrigerant is interrupted can be eliminated. Moreover, the rubber layer construction described above is employed, and thus, the tube for conducting a refrigerant of the present disclosure also has excellent bending resistance, water resistance, strength, and the like.

In particular, when the innermost layer is formed of a fluorine resin having a melt viscosity of 500 Pa · s to 3000 Pa · s, the flexibility of the tube becomes even better.

In addition, when the innermost layer is formed of at least one fluororesin selected from the group consisting of an ethylene-tetrafluoroethylene copolymer (ETFE), a polyvinylidene fluoride (PVDF), an ethylene-tetrafluoroethylene-hexafluoropropylene copolymer (EFEP), a tetrafluoroethylene Perfluoro (alkyl vinyl ether) chlorotrifluoroethylene copolymer (CPT), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and a chlorotrifluoroethylene-ethylene copolymer (ECTFE), the balance between the flexibility and the extraction resistance of the tube becomes even better.

In addition, when the innermost layer is formed of at least one resin selected from the group consisting of a maleic anhydride-modified fluororesin, an itaconic anhydride-modified fluororesin, and a citraconic anhydride-modified fluororesin, the interlayer adhesion with the polyamide resin layer becomes even better.

Moreover, if the innermost layer has a thickness in the range of 0.05 mm to 0.25 mm, the flexibility of the tube becomes even better without impairing its extraction resistance.

Moreover, when the innermost layer has a modulus of elasticity in the range of 600 MPa to 900 MPa, the bending resistance of the tube becomes even better.

Moreover, when the outer peripheral surface of the innermost layer disposed at an interface with the polyamide resin layer has hydroxyl groups, the interlayer adhesion between the polyamide resin layer and the innermost layer becomes even better.

Moreover, when the polyamide resin layer is formed of at least one polyamide resin selected from the group consisting of polyamide 6, polyamide 610 and polyamide 66, the refrigerant permeation resistance of the hose becomes even better.

In addition, when the polyamide resin layer is a polyamide resin layer in which an island phase dispersed in an elastomer is formed, the flexibility and the like of the tube become even better.

Moreover, when the tube is formed so that the thickness of the innermost layer is equal to or greater than the thickness of the polyamide resin layer, the flexibility and the like of the tube become even better.

Moreover, when the tube is formed so that the elastic modulus of the innermost layer is equal to or greater than the modulus of elasticity of the polyamide resin layer, the flexibility and the like of the tube become even better.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 4 is an explanatory view schematically showing a cross section of a tube for conducting a refrigerant of the present disclosure. FIG.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described in detail. It should be noted that the present disclosure is not limited to these embodiments.

As it is in the 1 10, a tube for conducting a refrigerant of the present disclosure is a tube for conducting a refrigerant, comprising: a tubular innermost layer 1 formed of a fluororesin, a polyamide resin layer 2 which is disposed so as to communicate with the outer peripheral surface of the innermost layer 1 in contact, a first layer of rubber 3a which is disposed so as to be in contact with the outer peripheral surface of the polyamide resin layer 2 is in contact, a reinforcing layer 4 which is disposed so as to be in contact with the outer peripheral surface of the first rubber layer 3a in contact, and a second rubber layer 3b which is disposed so as to be in contact with the outer peripheral surface of the reinforcing layer 4 in contact, wherein the polyamide resin layer 2 is formed of a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 or less.

The fluororesin layer, which serves as the formation material for the innermost layer 1 is not specifically limited. However, in view of improving the flexibility of the hose, it is preferable to use a fluororesin having a melt viscosity of 500 Pa · s to 3000 Pa · s, and a fluororesin having a melt viscosity of 800 Pa · s to 2000 Pa · s is more preferably used. The melt viscosity is a melt viscosity according to JIS K 7199 measured with a capillary rheometer under conditions of 280 ° C and a shear rate of 121.6 s ^-1 .

Moreover, in view of the balance between the flexibility and the extraction resistance of the hose, an ethylene-tetrafluoroethylene copolymer (ETFE), a polyvinylidene fluoride (PVDF), an ethylene-tetrafluoroethylene-hexafluoropropylene copolymer (EFEP), a tetrafluoroethylene-perfluoro (alkyl vinyl ether ) -Chlorotrifluoroethylene copolymer (CPT), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and a chlorotrifluoroethylene-ethylene copolymer (ECTFE) are preferably used. Moreover, one kind of these fluororesins are used alone or two or more kinds thereof are used in combination.

Moreover, with respect to the interlayer adhesion of the innermost layer 1 with the polyamide resin layer 2 a maleic anhydride-modified fluororesin, an itaconic anhydride-modified fluororesin or a citraconic anhydride-modified fluororesin is used as the fluororesin. The same resins as those described above are used as a suitable fluororesin which provides a basis for the modification.

When a modified fluororesin is used as described above, the innermost layer becomes 1 and the polyamide resin layer 2 preferably subjected to a coextrusion molding, so that the interlayer adhesion with the polyamide resin layer 2 can be further improved.

In addition, the interlayer adhesion with the polyamide resin layer becomes 2 even better if the outer peripheral surface of the innermost layer 1 Has hydroxyl groups. The hydroxyl groups are introduced by the outer peripheral surface of the innermost layer 1 is subjected to a plasma treatment, and this can be confirmed by an X-ray photoelectron spectroscopy.

As described above, a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 or less is used as the polyamide resin layer forming material 2 used. A polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 6 to 10 is preferably used. The value of Ca can be determined by calculating the number of carbon atoms per nitrogen atom from the number of nitrogen atoms and the number of carbon atoms in a molecule of the polyamide resin.

Examples of the polyamide resin as described above include polyamide 6 (Ca = 6), polyamide 610 (Ca = 8), polyamide 46 (Ca = 5), polyamide 66 (Ca = 6), polyamide 1010 (Ca = 10), polyamide 612 (Ca = 9), polyamide 1012 (Ca = 11), polyamide 6T (Ca = 7), polyamide 6T / 6I (Ca = 7), polyamide 66 / 6T (Ca = 7), polyamide 66 / 6T / 6I (Ca = 7), polyamide 6T / 2MPMDT (Ca = 7), polyamide 9T (Ca = 8.5), polyamide 10T (Ca = 9) and polyamide 11T (Ca = 9.5). One kind of these polyamide resins are used alone or two or more kinds thereof are used in combination. Of these, polyamide 6, polyamide 610 and polyamide 66 are suitably used because then the refrigerant permeation resistance of the hose becomes even better.

In addition, the polyamide resin layer 2 Preferably, a polyamide resin layer in which an island phase is dispersed, which is formed of an elastomer, since then the flexibility and the like of the hose are still better. Examples of the elastomer include an ethylene-α-olefin copolymer, an ionomer resin, a modified polyolefin (e.g., a maleic anhydride-modified ethylene-butene copolymer), a polyetheramide elastomer, a polyesteramide elastomer, a polyetheresteramide elastomer, a polyetherester elastomer, an acrylic rubber , an ethylene-propylene-based rubber, a butyl rubber, a nitrile rubber, a fluororubber, and a silicone rubber. Of these, an ethylene-α-olefin copolymer is preferred in view of flexibility and impact resistance.

When such a polyamide resin layer having a sea-island structure as described above is formed, the polyamide resin and the elastomer serving as the materials thereof are preferably in a weight ratio of polyamide resin / elastomer in view of the refrigerant permeation resistance of the hose "Mixed from 95/5 to 55/45.

The formation material for the polyamide resin layer 2 optionally in a suitable manner with an additive such. As a filler, a plasticizer or an anti-aging agent are mixed.

A forming material for each of the rubber layers on the outer periphery of the polyamide resin layer 2 (a first rubber layer 3a and a second rubber layer 3b ) is z. Example, a rubber such as a butyl rubber (IIR), a halogenated butyl rubber, such as. A chlorinated butyl rubber (CI-IIR) or a brominated butyl rubber (Br-IIR), an acrylonitrile-butadiene rubber (NBR), a chloroprene rubber (CR), an ethylene-propylene-diene rubber (EPDM), an ethylene Propylene rubber (EPM), a fluororubber (FKM), an epichlorohydrin rubber (ECO), an acrylic rubber, a silicone rubber, a chlorinated polyethylene rubber (CPE) or a urethane rubber suitably mixed with a vulcanizing agent, carbon black or the like , Of these, a butyl rubber (IIR) or a halogenated butyl rubber is suitably used since the hose becomes better in low refrigerant permeability and becomes excellent from the outside in terms of resistance to water. In addition, one kind of these materials are used alone or two or more kinds of them are used in combination.

In addition, as it can in the 1 is shown, the reinforcing layer 4 between the first rubber layer 3a and the second rubber layer 3b is arranged, for. By braiding a reinforcing yarn made of a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), an aramid, a polyamide (nylon), a polyvinyl alcohol (vinylon), a rayon, a metal wire or the like, by spiral braiding, knitted braid , Litzenflechten or the like are formed.

Such a hose described above for conducting a refrigerant of the present disclosure, as shown in the 1 is shown, for. B. be prepared in the manner described below. That is, first, the material for the innermost layer 1 and the material for the polyamide resin layer 2 , which have been described above, prepared. Next, the material for the innermost layer 1 and the material for the polyamide resin layer 2 subjected to coextrusion molding into a tube shape. In this case, a thorn can be used. In addition, if the innermost layer 1 of a material having poor interlayer adhesion with the polyamide resin layer 2 is formed, the following method can be used: The material for the innermost layer 1 is subjected in advance to extrusion molding into a tube shape and its outer peripheral surface is subjected to a plasma treatment, whereupon the polyamide resin layer 2 is extrusion molded. Then, the extrusion molding of the first rubber layer 3a on the outer peripheral surface of the polyamide resin layer 2 performed and then the reinforcing layer 4 formed by the outer peripheral surface of the layer 3a z. B. is subjected to a strand braiding with a reinforcing yarn. Further, the extrusion molding of the second rubber layer becomes 3b on the outer peripheral surface of the reinforcing layer 4 carried out. Then, the resulting tube under predetermined conditions (preferably 170 ° C × 30 minutes to 60 Minutes) and then the mandrel is removed. In this way, a hose for guiding a refrigerant having a desired layer structure can be manufactured.

In the tube for conducting a refrigerant of the present disclosure, the tube inner diameter is preferably within a range of 5 mm to 40 mm. In addition, the thickness of the innermost layer is 1 within the range of preferably from 0.05 mm to 0.25 mm, more preferably from 0.1 mm to 0.2 mm. This is due to the following reasons: When the thickness of the innermost layer 1 is excessively low, it becomes difficult to obtain a desired extraction resistance, and when the thickness of the innermost layer 1 is excessively large, the flexibility of the hose may be impaired.

In addition, the tube is preferably formed such that the thickness of the innermost layer 1 equal to the thickness of the polyamide resin layer 2 or larger than this, since then the flexibility and the like of the hose become better.

In addition, the tube is preferably formed such that the elastic modulus of the innermost layer 1 within the range of 600 MPa to 900 MPa, because then the bending resistance of the hose is better. The modulus of elasticity is determined according to ASTM D 790 measured.

In addition, the tube is preferably formed such that the elastic modulus of the innermost layer 1 equal to the modulus of elasticity of the polyamide resin layer 2 or larger than this, since then the flexibility and the like of the hose become better.

The hose for conducting a refrigerant of the present disclosure is preferably used as a hose for conducting a refrigerant such as a refrigerant. Carbon dioxide, a chlorofluorocarbon, an alternative chlorofluorocarbon or propane used in an air conditioner cooler or the like. The hose for conducting a refrigerant is preferably used not only for an automobile, but also for any other transportation machine (for example, an industrial transport vehicle such as an airplane, a forklift, an excavator or a crane, or a rail vehicle) or the like.

Next, examples of the present disclosure will be described along with comparative examples. However, the present disclosure is not limited to these examples.

First, before the Examples and Comparative Examples, the following materials were prepared as resin layer materials. In each of the following materials, the melt viscosity is a melt viscosity that is in accordance with JIS K 7199 was measured with a capillary rheometer under the conditions of 280 ° C and a shear rate of 121.6 s ^-1 . In addition, Ca represents the average number of carbon atoms per nitrogen atom in a polyamide resin.

[Fluororesin 1]

A polymerization tank with a stirrer and an internal volume of 13 liters was purged of air and 8500 g of 1-hydrotridecafluorohexane, 3650 g of 1,3-dichloro-1,1,2,2,3-pentafluoropropane and 26 g of CH ₂ = CH (CF ₂ ) ₄ F were introduced into the tank. 2100 grams of tetrafluoroethylene (hereinafter sometimes referred to as "TFE") and 1.2 grams of ethylene (hereinafter sometimes referred to as "E") were pressed into the polymerization tank and the temperature in the polymerization tank was raised to 66 ° C. 48 milliliters of a 0.5% by mass solution of tert-butyl peroxypivalate in 1-hydrotridecafluorohexane, which serves as a polymerization initiator, was introduced into the tank to initiate the polymerization. Then, a monomer mixed gas having a composition "TFE / E" of 70/30 (molar ratio) was continuously introduced into the tank such that the pressure became constant during the polymerization, and CH ₂ = CH (CF ₂ ) ₄ F was continuously introduced into the tank so that its content became 0.7 mol% with respect to the mixed monomer gas composed of TFE and E. 3 hours after the initiation of the polymerization, at the time when 900 g of the mixed monomer gas was introduced, the temperature in the polymerization tank was lowered to room temperature, and the tank was purged to normal pressure. The thus-obtained slurry was subjected to suction filtration with a glass filter and dried at 120 ° C for 15 hours to obtain 950 g of an ethylene-tetrafluoroethylene copolymer (ETFE1).

Then, the ETFE1 obtained in the manner described above and a maleic acid-modified ETFE having a melt viscosity of 1200 Pa · s (AH-2000, manufactured by Asahi Glass Co., Ltd.) were used. in a weight ratio "ETFE1: AH-2000" of 2: 1, so that a fluororesin 1 having a melt viscosity of 600 Pa · s was obtained.

[Fluororesin 2]

The ETFE1 obtained in the manner described above and a maleic acid-modified ETFE having a melt viscosity of 1200 Pa · s (AH-2000, manufactured by Asahi Glass Co., Ltd.) were used in a weight ratio "ETFE1: AH-2000" of FIG : 2, so that a fluororesin 2 having a melt viscosity of 800 Pa · s was obtained.

[Fluororesin 3]

A maleic acid-modified ETFE having a melt viscosity of 1200 Pa · s (AH-2000, manufactured by Asahi Glass Co., Ltd.) was used.

[Fluororesin 4]

A maleic acid-modified ETFE having a melt viscosity of 1200 Pa · s (AH-2000, manufactured by Asahi Glass Co., Ltd.) and an ETFE having a melt viscosity of 1700 Pa · s (C88AXP, manufactured by Asahi Glass Co., Ltd ) were mixed in a weight ratio "AH-2000: C88AXP" of 2: 1 so that a fluororesin 4 having a melt viscosity of 1400 Pa · s was obtained.

[Fluororesin 5]

An ETFE having a melt viscosity of 1700 Pa · s (C88AXP, manufactured by Asahi Glass Co., Ltd.) was used.

[Polyamide resin 1]

A polyamide 6 (Ca: 6) (CM1017, manufactured by Toray Industries, Inc.) was used.

[Polyamide resin 2]

A polyamide 610 (Ca: 8) (CM2006, manufactured by Toray Industries, Inc.) was used.

[Polyamide resin 3]

A polyamide 12 (Ca: 12) (30308, manufactured by Ube Industries, Ltd.) was used.

[Elastomer 1]

An ethylene-α-olefin copolymer (TAFMER MH7020, manufactured by Mitsui Chemicals, Inc.) was used.

[Example 1]

An innermost layer (thickness: 0.15 mm) formed of the fluororesin 1 and an outer layer (thickness: 0.15 mm) formed of a mixture of the polyamide resin 1 and the elastomer 1 (mixture having a Weight ratio "Polyamide Resin 1 / Elastomer 1" of 70/30) were subjected to coextrusion molding on a metal mandrel (outer diameter 12.7 mm). Then, a first rubber layer (thickness: 1.6 mm) was formed on the outer peripheral surface of the outer layer (polyamide resin layer) by extrusion molding an EPDM. Thereafter, a reinforcing layer was formed on the outer peripheral surface of the rubber layer by braiding an aramid yarn. Further, a second rubber layer (thickness: 1.0 mm) was formed on the outer peripheral surface of the reinforcing layer by extrusion molding an EPDM. Then, vulcanization was carried out, and then the mandrel was removed from the resulting laminated tubular body, whereupon an elongated molded article was cut. In this way, a desired hose for conducting a refrigerant has been prepared (refer to FIGS 1 ). Examination of the outer layer (polyamide resin layer) with an electron microscope confirmed that an island phase formed of the elastomer 1 was dispersed.

[Example 2]

The fluororesin 2 was used as the material for the innermost layer instead of the fluororesin 1. Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1.

[Example 3]

The fluororesin 3 was used as the material for the innermost layer instead of the fluororesin 1. Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1.

[Example 4]

The fluororesin 4 was used as the material for the innermost layer instead of the fluororesin 1. Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1.

[Example 5]

A mixture of the polyamide resin 2 and the elastomer 1 (mixture having a weight ratio "polyamide resin 2 / elastomer 1" of 70/30) was used in place of the mixture of the polyamide resin 1 and the elastomer 1 as the material for the outer layer polyamide resin layer). Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1. Examination of the outer layer (polyamide resin layer) with an electron microscope confirmed that an island phase formed of the elastomer 1 was dispersed.

[Example 6]

An innermost layer (thickness: 0.15 mm) formed of the fluorine resin 5 was subjected to extrusion molding on a metal mandrel (outer diameter 12.7 mm), and then the outer peripheral surface of the innermost layer was subjected to a plasma treatment. Thereafter, an outer layer (thickness: 0.15 mm) formed of a mixture of the polyamide resin 1 and the elastomer 1 (mixture having a weight ratio "polyamide resin 1 / elastomer 1" of 70/30) was extrusion-molded onto the outer peripheral surface subjected to the innermost layer. Then, a first rubber layer (thickness: 1.6 mm) was formed on the outer peripheral surface of the outer layer (polyamide resin layer) by extrusion molding an EPDM. Thereafter, a reinforcing layer was formed on the outer peripheral surface of the rubber layer by braiding an aramid yarn. Further, a second rubber layer (thickness: 1.0 mm) was formed on the outer peripheral surface of the reinforcing layer by extrusion molding an EPDM. Then, vulcanization was carried out, and then the mandrel was removed from the resulting laminated tubular body, whereupon an elongated molded article was cut. In this way, a desired hose for conducting a refrigerant was prepared. Examination of the outer layer (polyamide resin layer) with an electron microscope confirmed that an island phase formed of the elastomer 1 was dispersed.

Comparative Example 1

An innermost layer (thickness: 0.15 mm) formed of a mixture of the polyamide resin 1 and the elastomer 1 (mixture having a weight ratio "polyamide resin 1 / elastomer 1" of 70/30) was extrusion-molded onto a metal mandrel (Outer diameter 12.7 mm) subjected. Then, a first rubber layer (thickness: 1.6 mm) was formed on the outer peripheral surface of the innermost layer by extrusion molding an EPDM. Thereafter, a reinforcing layer was formed on the outer peripheral surface of the rubber layer by braiding an aramid yarn. Further, a second rubber layer (thickness: 1.0 mm) was formed on the outer peripheral surface of the reinforcing layer by extrusion molding an EPDM. Then, vulcanization was carried out, and then the mandrel was removed from the resulting laminated tubular body, whereupon an elongated molded article was cut. In this way, a desired hose for conducting a refrigerant was prepared.

Comparative Example 2

An innermost layer (thickness: 0.15 mm) formed of a mixture of the polyamide resin 3 and the elastomer 1 (mixture having a weight ratio "polyamide resin 3 / elastomer 1" of 70/30) was extrusion-molded onto a metal mandrel (Outer diameter 12.7 mm) subjected. Then, a first rubber layer (thickness: 1.6 mm) was formed on the outer peripheral surface of the innermost layer by extrusion molding an EPDM. Thereafter, a reinforcing layer was formed on the outer peripheral surface of the rubber layer by braiding an aramid yarn. Further, a second rubber layer (thickness: 1.0 mm) was formed on the outer peripheral surface of the reinforcing layer by extrusion molding an EPDM. Then, vulcanization was carried out, and then the mandrel was removed from the resulting laminated tubular body, whereupon an elongated molded article was cut. In this way, a desired hose for conducting a refrigerant was prepared.

Comparative Example 3

A mixture of the polyamide resin 3 and the elastomer 1 (mixture having a weight ratio "polyamide resin 3 / elastomer 1" of 70/30) was used in place of the mixture of the polyamide resin 1 and the elastomer 1 as the material for the outer layer (polyamide resin layer). Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1.

Comparative Example 4

A polyolefin resin (B241, manufactured by Prime Polymer Co., Ltd.) was used instead of the fluororesin 1 as the material for the innermost layer. Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1.

Comparative Example 5

A maleic acid-modified polyolefin resin (ADMER QF551, manufactured by Mitsui Chemicals, Inc.) was used in place of the fluororesin 1 as the material for the innermost layer. Other than the above, a desired tube for conducting a refrigerant was prepared in the same manner as in Example 1.

The thus obtained tubes for conducting a refrigerant of Examples and Comparative Examples were evaluated for their respective properties according to the following criteria. The results are shown together in Tables 1 and 2 below.

<< >> Kältemitteldurchdringungsbeständigkeit

Each of the tubes of Examples and Comparative Examples was cut in its longitudinal direction and then punched in a disk shape to prepare a sample sheet. Then, the opening portion of a cup filled with an alternative chlorofluorocarbon gas (HFC-134a) at a low temperature (-35 ° C or lower) was sealed with the sample layer, and the resultant assembly was allowed to stand in an oven at 90 ° C. Then, the reduction amounts of the alternative chlorofluorocarbon gas in the beaker were plotted against time, and the permeation amount of the alternative chlorofluorocarbon gas per day with respect to the permeation area of the sample layer (HFC-134a permeation coefficient, mg.mm/cm ² .day) was determined from the slope of Plots calculated. A tube with a permeation rate of the alternative chlorofluorocarbon gas per day of 0.3 mg.mm/cm ² .day) or less was rated o.

<< modulus >>

The modulus of elasticity (MPa) of the resin layer (the innermost layer or the outer layer) of a hose for conducting a refrigerant was determined according to FIG ASTM D 790 measured.

<< extraction resistance >>

A mixed liquid of 50 g of a refrigerant (HFC-134a) and 30 g of an oil (Daphne Hermetic Oil) was filled in a hose for passing a refrigerant having a hose length of 400 mm, and Opening portions at both ends of the hose were plugged. Thereafter, the tube was allowed to stand in an oven at 150 ° C for 168 hours. Thereafter, a removed extracted liquid was applied to filter paper and dried, and the presence or absence of an extract on the filter paper was examined with a microscope. A tube in which the extract was not detected was rated o, and a tube where the extract was detected was rated x.

<< heat resistance >>

A test piece ( Dumbbell JIS No. 5 ) made of a material for the resin layer (innermost layer or outer layer) of a tube for conducting a refrigerant was allowed to stand for thermal aging for 168 hours at 150 ° C in a Geer oven. Thereafter, the specimen was bent through 180 ° and, by examining the appearance of the specimen, it was evaluated whether or not an abnormality such as anomaly was caused. For example, the occurrence of a crack or sag in which the specimen was absent or not. A tube in which the abnormality was not detected from each of the test pieces of the innermost layer and the outer layer was evaluated as ○, and a hose in which the anomaly was found in at least one of the test pieces of the innermost layer and the outer layer was included x rated.

<< interlayer adhesion >>

A hose for conducting a refrigerant was cut to have a width of 10 mm. In this way, a strip-shaped sample was prepared. Then, the resin layers (the innermost layer and the outer layer) of each sample were partially peeled off each other, and each of the detached portions was set in a chuck of a tensile tester, followed by measurement of the 90 ° peel strength (N / cm) under the conditions of an ambient temperature of 23 ° C and a pulling speed of 25 mm / min was performed. A tube in which the peel strength was 30 N / cm or more was evaluated as ○, and a tube in which the peel strength was less than 30 N / cm was evaluated as x.

<< flexibility >>

A hose for conducting a refrigerant was wound around a tubular cylinder (mandrel) having a diameter of 200 mm, and then evaluated for its flexibility on the basis of the extent to which the hose was wound. The tubing was rated o if the resin layer of the tubing did not kink (compress) due to wrapping.

<< WITH Test >>

A hose for conducting a refrigerant was cut to have a width of 10 mm. In this way, a strip-shaped sample was prepared. Then each sample was subjected to an MIT test JIS P 8115 subjected to an ambient temperature of 120 ° C, a load of 250 g, a bending angle of 135 ° and a test cycle of 175 cpm. A tube in which the tearing of the sample did not occur even in a number of reciprocating 10,000 or more was rated o. Table 1 example 1 2 3 4 5 6 Kältemitteldurchdringungsbeständigkeit O O O O O O Young's modulus (MPa) Innermost layer 600 700 800 900 600 700 outer layer 600 600 600 600 600 600 extraction resistance O O O O O O heat resistance O O O O 0 O Interlayer adhesion O O O O O O flexibility O O O O O O WITH Test O O O O O O Table 2 Comparative example 1 2 3 4 5 Kältemitteldurchdringungsbeständigkeit O O O O O Young's modulus (MPa) Innermost layer 600 600 600 700 700 outer layer - - 600 600 600 Extraktionsbesändigkeit x x O O O heat resistance O x x x x Interlayer adhesion - - O x O flexibility O O O O O WITH Test O O O O O

As apparent from the results of the table, each of the tubes of the examples is excellent in the refrigerant permeation resistance and the heat resistance and excellent in the extraction resistance. In addition, each of the tubes of Examples had very good interlayer adhesion between the resin layers and had satisfactory results in the flexibility and the MIT test.

In contrast, the tubes of Comparative Examples 1 and 2 had poor results in terms of extraction resistance and the like. The tube of Comparative Example 3 comprising the outer layer made of the mixture of polyamide 12 had a poor result in evaluation of heat resistance. The tube of Comparative Example 4 comprising the innermost layer made of the polyolefin resin had poor results in evaluation of heat resistance and interlayer adhesion. The tube of Comparative Example 5 comprising the innermost layer made of the acid-modified polyolefin resin had a poor result in the evaluation of heat resistance.

The hose for conducting a refrigerant of the present disclosure is preferably used as a hose for conducting a refrigerant such as a refrigerant. Carbon dioxide, a chlorofluorocarbon, an alternative chlorofluorocarbon or propane used in an air conditioner cooler or the like. The hose for conducting a refrigerant is preferably used not only for an automobile, but also for any other transportation machine (for example, an industrial transport vehicle such as an airplane, a forklift, an excavator or a crane, or a rail vehicle) or the like.

Although specific forms of embodiments of the present disclosure have been described above for a better understanding, the foregoing description has been given by way of example only and is not to be construed as limiting the scope of the present disclosure. It is intended that various modifications that would be obvious to those skilled in the art could be made without departing from the scope of the disclosure.

LIST OF REFERENCE NUMBERS

1

Tubular innermost layer

2

Polyamide resin layer

3a

First rubber layer

3b

Second rubber layer

4

reinforcing layer

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2002-181254 A [0003]

Cited non-patent literature

• JIS K 7199 [0022]
• ASTM D 790 [0037]
• JIS K 7199 [0041]
• ASTM D 790 [0065]
• Dumbbell JIS No. 5 [0067]
• JIS P 8115 [0070]

Claims (11)

Hose for conducting a refrigerant, comprising: a tubular innermost layer formed of a fluorine resin, a polyamide resin layer disposed so as to be in contact with an outer peripheral surface of the innermost layer, a first rubber layer disposed so as to be in contact with an outer peripheral surface of the polyamide resin layer, a reinforcing layer disposed so as to be in contact with an outer circumferential surface of the first rubber layer, and a second rubber layer disposed so as to be in contact with an outer circumferential surface of the reinforcing layer, wherein the polyamide resin layer is formed of a polyamide resin having an average number Ca of carbon atoms per nitrogen atom of 10 or less. A hose for conducting a refrigerant according to claim 1, wherein the innermost layer is formed of a fluorine resin having a melt viscosity of 500 Pa · s to 3000 Pa · s. A hose for conducting a refrigerant according to claim 1 or 2, wherein the innermost layer is formed of at least one fluororesin selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a polyvinylidene fluoride, an ethylene-tetrafluoroethylene-hexafluoropropylene copolymer, a Tetrafluoroethylene-perfluoro (alkyl vinyl ether) -chlorotrifluoroethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and a chlorotrifluoroethylene-ethylene copolymer. A tube for conducting a refrigerant according to any one of claims 1 to 3, wherein the innermost layer is formed of at least one resin selected from the group consisting of a maleic anhydride modified fluororesin, an itaconic anhydride modified fluororesin and a citraconic anhydride modified fluororesin, is selected. A tube for conducting a refrigerant according to any one of claims 1 to 4, wherein the innermost layer has a thickness in the range of 0.05 mm to 0.25 mm. A hose for conducting a refrigerant according to any one of claims 1 to 5, wherein the innermost layer has a modulus of elasticity in the range of 600 MPa to 900 MPa. A hose for conducting a refrigerant according to any one of claims 1 to 6, wherein the outer peripheral surface of the innermost layer, which is disposed at an interface with the polyamide resin layer, has hydroxyl groups. A hose for conducting a refrigerant according to any one of claims 1 to 7, wherein the polyamide resin layer is formed of at least one polyamide resin selected from the group consisting of polyamide 6, polyamide 610 and polyamide 66. A hose for conducting a refrigerant according to any one of claims 1 to 8, wherein the polyamide resin layer comprises a polyamide resin layer in which an island phase is dispersed, which is formed of an elastomer. A tube for conducting a refrigerant according to any one of claims 1 to 9, wherein the tube for guiding a refrigerant is formed so that the thickness of the innermost layer is equal to or greater than the thickness of the polyamide resin layer. A tube for conducting a refrigerant according to any one of claims 1 to 10, wherein the tube for conducting a refrigerant is formed so that the elastic modulus of the innermost layer is equal to or greater than the elastic modulus of the polyamide resin layer.

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