Hose for refrigerant transportation

Abstract

To provide a hose for refrigerant transportation which is excellent in resistance against refrigerant permeability and flexibility, and is excellent in hydrolysis deterioration prevention performance of a hose innermost layer.SOLUTION: A hose for refrigerant transportation is provided, comprising a tubular innermost layer 1, and a rubber layer 2 provided on the outer periphery of the innermost layer 1, wherein a polymer for the innermost layer 1 is a blend polymer (A) composed of the following component (A-1) as a main component and component (A-2), the innermost layer 1 contains the following component (B) in a specific range with respect to 100 pts.mass of the blend polymer (A), and is composed of an alloy where an island phase of the following component (A-2) is dispersed in a sea phase of the following component (A-1). (A-1) Polyamide resin. (A-2) Polyolefinic elastomer. (B) Sulfur-based compound having diphenyl sulfide structure in one molecule.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a refrigerant transport hose that is useful as a hose for transporting a refrigerant for vehicles such as automobiles.

Background Art

[0002] With the strengthening of regulations on the evaporation of ozone-depleting gases, the requirements for the refrigerant barrier property (refrigerant permeability resistance) of refrigerant transport hoses used in automobiles and the like have become stricter. Under such circumstances, conventionally, for the forming material of the innermost layer of a refrigerant transport hose, a highly crystalline resin such as a polyamide resin has been used (see, for example, Patent Documents 1 to 4).

[0003] On the other hand, with the strengthening of regulations on the evaporation of ozone-depleting gases, in recent years, the quality of refrigerants used in automobiles and the like has also been improved. For example, the R-1234yf refrigerant (HFO-1234yf refrigerant) was developed as an alternative refrigerant to the HFC-134a refrigerant, and has a lower ozone depletion coefficient and global warming coefficient than HFC-134a, making it an extremely environmentally friendly refrigerant. Therefore, refrigerant transport hoses used in automobiles and the like are also required to have performance suitable for R-1234yf.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when using a refrigerant composition containing a fluorine compound having a double bond, such as R-1234yf refrigerant, and a lubricating oil (refrigeration oil), under a high-temperature environment, organic acids and inorganic acids are generated due to the decomposition of the fluorine compound and the lubricating oil. And there is a problem that the polyamide resin constituting the innermost layer of the hose is hydrolyzed and deteriorated by contact with the organic acid and the inorganic acid.

[0006] Here, the hose according to Patent Document 1 includes an innermost layer in which a divalent or trivalent metal compound is blended in a polyamide resin, and the hose according to Patent Document 2 includes an innermost layer in which a carbodiimide of an organic compound is blended in a polyamide resin, and the hose according to Patent Document 3 includes an innermost layer in which hydrotalcite is blended in a polyamide resin. With these methods, an improvement in hydrolysis prevention performance (acid resistance) can be seen to some extent. However, for example, as shown in Patent Document 1, when a metal compound (inorganic compound) is added, problems such as the promotion of the curing of the polyamide resin and the decrease in flexibility, or the promotion of the oxidative degradation reaction of the polyamide resin and the significant deterioration of the heat resistance occur. Also, as shown in Patent Document 2, when a carbodiimide of an organic compound is added, problems such as the reaction between its imide group and the carboxy group or hydroxy group of the polyamide resin, and the occurrence of a crosslinking reaction between polymers to obtain a chain extension effect, resulting in a decrease in flexibility occur. Also, as shown in Patent Document 3, when hydrotalcite is added, the hydrolysis prevention performance (acid resistance) cannot be improved unless a large amount of it is added. Due to the addition of a large amount, problems such as a decrease in flexibility and a decrease in moldability such as biaxial kneading and extrusion of the polyamide resin occur. Therefore, there is still room for improvement.

[0007] In addition, in order to solve the above problems, the applicant has already proposed a technique of stably sealing an acid that reacts with a polyamide resin by incorporating an aromatic secondary amine compound having two secondary amino groups in one molecule and a melting point of 100 °C or higher into the innermost layer of a hose made of a polyamide resin, as shown in Patent Document 4. The inventors of the present invention have also been conducting research on material configurations different from those of the hoses shown in Patent Document 4, and as a result, have developed an improved hose with further enhanced hose performance.

[0008] The present invention has been made in view of such circumstances, and an object thereof is to provide a refrigerant transport hose that is excellent in refrigerant permeation resistance, flexibility, etc., and also excellent in the performance of preventing hydrolysis degradation of the innermost layer of the hose.

Means for Solving the Problems

[0009] That is, the inventors of the present invention have conducted intensive research to solve the above problems. In the process of that research, from the viewpoints of refrigerant permeation resistance, flexibility, etc., similar to the hose disclosed in Patent Document 4, the innermost layer of the hose is made of an alloy in which a polyolefin-based elastomer is dispersed in a polyamide resin, and further, in order to enhance the hose strength, flex resistance, and water resistance, it was considered to provide a rubber layer on the outer periphery of the innermost layer. Then, in order to suppress the hydrolysis of the polyamide resin caused by organic acids and inorganic acids generated from the refrigerant, various compounds were added to the innermost layer, and repeated research was conducted on whether the acid that reacts with the polyamide resin could be stably sealed. As a result, when a compound having a diphenyl sulfide bond in the molecule, which functions as a hydrolysis inhibitor, was contained in the innermost layer, even if the content of the compound was small, the hydrogen ions (H +) and negative ions can be effectively captured by the S atom (sulfur atom) in the diphenyl sulfide bond of the compound to form a stable salt. The reason for this is considered to be that the S atom in the diphenyl sulfide bond is electron-rich, and further, steric hindrance is likely to occur around the S atom, resulting in specialization for acid acceptance. And by forming the innermost layer as described above, hydrolysis of the polyamide resin, which is the innermost layer material, is suppressed, so that the refrigerant gas barrier property is improved. Further, since higher performance improvements in hydrolysis resistance, flexibility, etc. were recognized compared to the hose disclosed in Patent Document 4, it was found that the intended purpose could be achieved, and the present invention was reached.

[0010] That is, in order to achieve the above object, the gist of the present invention is as follows [1] to [5]. [1] A refrigerant transport hose including a tubular innermost layer and a rubber layer provided on the outer periphery of the innermost layer, wherein the polymer for the innermost layer is a blend polymer (A) composed of the following component (A-1) and component (A-2) with the following component (A-1) as the main component, the innermost layer contains the following component (B) in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the blend polymer (A), and an alloy in which an island phase of the following component (A-2) is dispersed in a sea phase of the following component (A-1), a refrigerant transport hose. (A-1) A polyamide resin. (A-2) A polyolefin-based elastomer. (B) A sulfur-based compound having a molecular structure represented by the following formula (1) in one molecule. [Chemical formula] [2] The refrigerant transport hose according to [1], wherein the component (A-1) in the innermost layer is at least one aliphatic polyamide resin selected from the group consisting of polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, and polyamide 1010. [3] In the innermost layer, the component (B) is unevenly distributed in the marine phase of the component (A-1). The refrigerant transport hose according to [1] or [2]. [4] Further, the innermost layer contains the following component (C). The refrigerant transport hose according to any one of [1] to [3]. (C) Aromatic amine compound. [5] The refrigerant transport hose according to [4], wherein the component (C) is 2-mercaptobenzimidazole. [Advantages of the Invention]

[0011] The refrigerant transport hose of the present invention includes a tubular innermost layer and a rubber layer provided on the outer periphery of the innermost layer. The innermost layer is made of an alloy in which a polyolefin-based elastomer is dispersed in a polyamide resin, and in the innermost layer, a sulfur-based compound having the molecular structure represented by the formula (1) (a compound having a diphenyl sulfide bond in one molecule) is contained in a specific ratio. Therefore, it is excellent in refrigerant permeation resistance, flexibility, etc., and also excellent in the performance of preventing hydrolysis deterioration of the innermost layer of the hose. As a result, it can be used well not only for conventional refrigerants and water but also for refrigerants that tend to be acidic, such as R-1234yf refrigerant. Further, the refrigerant transport hose of the present invention is also excellent in bending resistance, water resistance, hose strength, etc. due to the rubber layer provided on the outer periphery of the innermost layer. [Brief Description of the Drawings]

[0012]

Figure 1

[0013] Next, a refrigerant transport hose (hereinafter referred to as "this refrigerant transport hose"), which is an embodiment of the present invention, will be described in detail. However, the present invention is not limited to this embodiment.

[0014] As shown in Fig. 1, this refrigerant transfer hose includes a tubular innermost layer 1 and a rubber layer 2 provided on the outer periphery of the innermost layer 1. The polymer for the innermost layer 1 is a blend polymer (A) composed of the following component (A-1) and component (A-2) with the following component (A-1) as the main component. Here, the "main component" of the polymer means 50% by mass or more of the whole polymer. And the innermost layer 1 contains the following component (B) in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the blend polymer (A), and is made of an alloy in which an island phase of the following component (A-2) is dispersed in the sea phase of the following component (A-1). (A-1) Polyamide resin. (A-2) Polyolefin-based elastomer. (B) A sulfur-based compound having the molecular structure shown in the following formula (1) in one molecule.

Chemical formula

[0015] Examples of the polyamide resin (A-1) used as the polymer for the innermost layer 1 include aliphatic polyamide resins such as polyamide 46 (PA46), polyamide 6 (PA6), polyamide 66 (PA66), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 1010 (PA1010), and aromatic polyamide resins such as polyamide 6T (PA6T), polyamide 9T (PA9T), polyamide 10T (PA10T). These can be used alone or in combination of two or more. Among them, aliphatic polyamide resins are preferred because of their excellent flexibility and refrigerant permeability resistance. More preferably, PA46, PA6, PA66, PA610, PA612, PA1010 are used, and even more preferably, PA6 and PA66 are used.

[0016] In the polymer for the innermost layer 1, a polyolefin-based elastomer (A-2) is blended together with the polyamide resin (A-1). Then, as described above, a fine alloy structure is formed in which the island phase (domains) of the polyolefin-based elastomer (A-2) are dispersed in the sea phase (matrix) of the polyamide resin (especially aliphatic polyamide resin) (A-1). Therefore, the refrigerant gas barrier property of the polyamide resin is not impaired, and further improvement effects such as flexibility and durability can be obtained. Such an alloy structure can be confirmed, for example, by observing the innermost layer 1 with a scanning electron microscope (SEM). From the viewpoint of improving hydrolysis resistance, it is preferable that the specific sulfur-based compound (B) is unevenly distributed in the sea phase (matrix) of the (A-1). Such uneven distribution can be confirmed, for example, by energy dispersive X-ray spectroscopy.

[0017] Examples of the polyolefin-based elastomer (A-2) include polyethylene, polypropylene, polymethylpentene, ethylene-butene copolymer, ethylene-propylene copolymer (EPR), ethylene-propylene-diene terpolymer (EPDM), isoprene rubber (IR), styrene-ethylene-butylene-styrene copolymer (SEBS), modified ethylene-butene copolymer, ethylene-ethyl acrylate copolymer (EEA), modified EEA, modified EPR, modified EPDM, ionomer, α-olefin copolymer, modified IR, modified SEBS, halogenated isobutylene-p-methylstyrene copolymer, ethylene-acrylic acid modified product, ethylene-vinyl acetate copolymer, and acid-modified product of ethylene-vinyl acetate copolymer, and mixtures mainly composed of these. These can be used alone or in combination of two or more.

[0018] And in the blend polymer (A) of the polyamide resin (A-1) and the polyolefin-based elastomer (A-2) as described above, the content ratio of the polyamide resin (A-1) and the polyolefin-based elastomer (A-2) is usually in the range of (A-1) / (A-2) = 50 / 50 to 99 / 1 by mass ratio, and it is preferable from the viewpoints of flexibility, durability, etc. that (A-1) / (A-2) is in the range of 50 / 50 to 90 / 10. From the same viewpoints, more preferably, (A-1) / (A-2) is in the range of 60 / 40 to 90 / 10, and even more preferably, (A-1) / (A-2) is in the range of 60 / 40 to 80 / 20.

[0019] Further, the innermost layer 1 contains the following component (B) in a proportion of 0.5 to 20 parts by mass with respect to 100 parts by mass of the blend polymer (A). The proportion of the following component (B) with respect to 100 parts by mass of the blend polymer (A) is preferably in the range of 0.5 to 10 parts by mass, and more preferably in the range of 0.5 to 7.0 parts by mass. When the following component (B) is contained within such a range, the component (B) is sufficiently dispersed in the blend polymer and the moldability is not impaired, so that a good hydrolysis prevention effect (hydrolysis resistance) can be obtained. (B) A sulfur-based compound having the molecular structure represented by the following formula (1) in one molecule.

[0020]

Chemical formula

[0021] The sulfur-based compound (B) is not particularly limited as long as it has the molecular structure represented by the formula (1) in one molecule, but from the viewpoint of favorably expressing the hydrolysis prevention action, etc., its melting point is preferably 30 to 350°C, more preferably 90 to 320°C, and even more preferably 110 to 300°C.

[0022] Further, from the viewpoint of favorably exhibiting the hydrolysis prevention effect and the like, the sulfur-based compound (B) is preferably a compound having a structure in which only a functional group is bonded to the benzene ring having the molecular structure represented by the above formula (1) in addition to a hydrogen atom. Examples of the functional group include a hydroxy group, an alkyl group having 1 to 18 carbon atoms (preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 9 carbon atoms), and the like.

[0023] Specifically, the sulfur-based compound (B) is preferably a compound represented by the following chemical formula (2) (4,4'-thiobis(6-tert-butyl-3-methylphenol)).

[0024] [Chemical formula]

[0025] As the sulfur-based compound (B) as described above, among commercially available products, Nocrack 300 manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. can be preferably used.

[0026] In addition, an aromatic amine compound (C) can be blended with the sulfur-based compound (B) as needed in the material for forming the innermost layer 1. Thus, by using the aromatic amine compound (C) in combination with the sulfur-based compound (B), it acts as a secondary acid scavenger by π-π stacking interaction, and a better acid-receiving effect can be obtained, thereby further enhancing the hydrolysis prevention effect and the like.

[0027] From the viewpoint of favorably exhibiting the hydrolysis prevention effect and the like, the melting point of the aromatic amine compound (C) is preferably 30 to 350°C, more preferably 90 to 320°C, and even more preferably 110 to 300°C.

[0028] Specific examples of the aromatic amine compound (C) include N,N'-di-naphthyl-ρ-phenylenediamine, 2-mercaptobenzimidazole, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, 2-undecylimidazole, styrenated diphenylamine, 4,4',4"-tris(N,N-phenyl-m-tolylamino)triphenylamine, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-(1,3-phenylenediisopropylidene)bisaniiline, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, and the like. These may be used alone or in combination of two or more. Among them, from the viewpoint of obtaining a better hydrolysis prevention effect and the like, N,N'-di-naphthyl-ρ-phenylenediamine, 2-mercaptobenzimidazole, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine are preferable, and in particular, N,N'-di-naphthyl-ρ-phenylenediamine is suitable. Also, from the viewpoint of flexibility and the like, 2-mercaptobenzimidazole is suitable.

[0029] As commercially available aromatic amine compounds of the above type, Nocrack white, Nocrack CD, and Nocrack MB manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. can be preferably used.

[0030] And in the innermost layer 1, it is preferable that the aromatic amine compound (C) is contained in a proportion of 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the blend polymer (A). That is, when the aromatic amine compound (C) is contained within such a range, the component (C) can be sufficiently dispersed in the blend polymer without impairing the moldability, and a good hydrolysis prevention effect can be obtained.

[0031] In addition to the above materials, additives such as fillers, plasticizers, antioxidants, etc. can be appropriately blended into the forming material of the innermost layer 1 as required.

[0032] As the material for forming the rubber layer 2 provided on the outer periphery of the innermost layer 1, for example, halogenated butyl rubbers such as butyl rubber (IIR), chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), fluororubber (FKM), epichlorohydrin rubber (ECO), acrylic rubber, silicone rubber, chlorinated polyethylene rubber (CPE), urethane rubber, etc. are used alone or in combination of two or more. In addition to the above rubber, a crosslinking agent (vulcanizing agent), carbon black, etc. are appropriately blended.

[0033] In particular, it is preferable that the rubber layer 2 is made of a rubber composition containing a peroxide crosslinking agent, because the interlayer adhesion with the innermost layer 1 becomes excellent. An adhesive may be appropriately applied between the innermost layer 1 and the rubber layer 2.

[0034] In FIG. 1, the rubber layer 2 has a single-layer structure, but it may have a laminated structure of two or more layers. When the rubber layer 2 has two or more layers, the rubber compositions forming each layer may be the same or different. In addition, between the two or more rubber layers, a reinforcing layer formed by braiding reinforcing yarns such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid, polyamide (nylon), polyvinyl alcohol (vinylon), rayon, metal wire, etc. by spiral braiding, knit braiding, blade braiding, etc. may be provided.

[0035] Here, the refrigerant transport hose as shown in FIG. 1 can be manufactured, for example, as follows. That is, first, each material for forming the innermost layer 1 described above is melt-mixed at 150°C to 350°C to prepare a resin composition for forming the innermost layer 1. Also, a material for the rubber layer 2 is prepared. Next, the resin composition for forming the innermost layer 1 and the material for the rubber layer 2 are co-extrusion molded into a hose shape. At this time, a mandrel may be used. Also, after the resin composition for forming the innermost layer 1 is extrusion molded into a hose shape first, the rubber layer 2 may be extrusion molded. Then, after vulcanizing this under predetermined conditions (preferably at 170°C for 30 to 60 minutes), the mandrel is removed. In this way, a refrigerant transport hose having the desired layer structure can be manufactured.

[0036] In this refrigerant transport hose, the inner diameter of the hose is preferably in the range of 5 to 40 mm. Also, the thickness of the innermost layer 1 is preferably in the range of 0.05 to 0.50 mm, particularly preferably in the range of 0.10 to 0.20 mm. That is, if the thickness of the innermost layer 1 is too thin, it is difficult to obtain the desired refrigerant permeation resistance, and if the thickness of the innermost layer 1 is too thick, the vibration absorption property may deteriorate. On the other hand, the thickness of the rubber layer 2 is usually set in the range of 1 to 39 mm from the viewpoint of pressure resistance.

[0037] This refrigerant transport hose is suitably used for transporting refrigerants such as carbon dioxide, freon, alternative freon, propane, water, etc. used in air conditioners, radiators, etc., as well as refrigerants that tend to be acidic like R-1234yf refrigerant. And the refrigerant transport hose is preferably used not only for automobiles but also for other transport machines (industrial transport vehicles such as airplanes, forklifts, excavators, cranes, etc., railway vehicles, etc.) and vending machines, etc.

Examples

[0038] Next, the examples of the present invention will be described together with comparative examples. However, the present invention is not limited to these examples.

[0039] First, prior to the examples and comparative examples, the following materials were prepared as the innermost layer materials.

[0040] 〔Polyamide resin 1〕 Polyamide 6 (CM1017, manufactured by Toray Industries, Inc.)

[0041] 〔Polyamide resin 2〕 Polyamide 66 (Leonar 1700S, manufactured by Asahi Kasei Corporation)

[0042] 〔Elastomer〕 Polyolefin-based elastomer (Tafmer MH7010, manufactured by Mitsui Chemicals, Inc.)

[0043] 〔Sulfur-based compound 1〕 4,4’-Thiobis(6-tert-butyl-3-methylphenol) (No Crack 300, melting point: 155°C, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.)

[0044] 〔Sulfur-based compound 2〕 2,2-Thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox-1035, manufactured by BASF SE)

[0045] 〔Aromatic amine compound 1〕 N,N’-Di-naphthyl-ρ-phenylenediamine (No Crack white, melting point: 225°C, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.)

[0046] 〔Aromatic amine compound 2〕 2-Mercaptobenzimidazole (No Crack MB, melting point: 285°C, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.)

[0047] [Examples 1 to 7, Comparative Examples 1 to 4] Each material (innermost layer material) shown in Table 1 below was melt-mixed at 260°C at the ratio shown in Table 1 below to prepare a polyamide resin composition for forming the innermost layer. Next, melt extrusion molding of the polyamide resin composition for forming the innermost layer was performed on a resin mandrel (outer diameter 8 mm). On the outer peripheral surface of the innermost layer (thickness 0.2 mm) thus formed, extrusion molding of EPDM containing a peroxide crosslinking agent was performed and heat-crosslinked to form a rubber layer (thickness 0.5 mm). Then, after the heat crosslinking, the mandrel was removed from this laminated hose body, and the target refrigerant transport hose was produced by cutting the long molded product (see Figure 1).

[0048] Regarding the refrigerant transport hoses of the examples and comparative examples thus obtained, evaluations of each characteristic were performed according to the following criteria. The results are shown together with Table 1 below.

[0049] <Hydrolysis resistance> Test pieces (DIN 53504-S3A dumbbell) collected from the innermost layer of each hose of the examples and comparative examples were put into a mixed solution (concentration 10,000 ppm) prepared by adding 450 μl of water to 45 g of oil (Daphne Hermetic Oil, manufactured by Idemitsu Kosan Co., Ltd.). Subsequently, vacuum pumping was performed on the mixed solution into which the test pieces were put at a low temperature (-35°C) for 30 seconds, 60 g of alternative Freon gas (R-1234yf) was added, and then the mixed solution into which the test pieces were put was left standing in an oven at 140°C for 72 hours. Then, for the test pieces taken out from the mixed solution, a tensile test was performed in accordance with JIS K 6251 at an ambient temperature of 23°C and a tensile speed of 200 mm / min, and the tensile elongation (%) at the time when the test pieces broke was measured. And taking the tensile elongation (%) of Example 1 as 100 in exponential notation, the values of each tensile elongation (%) were converted into an index. As an evaluation of hydrolysis resistance, evaluation was performed according to the following criteria. ○ The value of the index is 70 or more. × The value of the index is less than 70.

[0050] <Flexibility> By injection molding the innermost layer material of each hose in the examples and comparative examples, a test piece for flexural evaluation with a thickness of 6.4 mm, a width of 1.27 mm, and a length of 127 mm was produced. For the test piece, in accordance with ASTM D790, the flexural modulus (MPa) was measured. Then, taking the flexural modulus of Example 1 as 100 in exponential notation, the values of each flexural modulus (MPa) were converted to exponents. As an evaluation of flexibility, it was evaluated according to the following criteria. ○ The value of the exponent is 170 or less. × The value of the exponent exceeds 170.

[0051]

Table 1

[0052] From the results in Table 1 above, it can be seen that all the hoses in the examples are excellent in hydrolysis resistance and flexibility. When the innermost layers of the hoses of Examples 1 to 7 were observed with a scanning electron microscope (SEM), it was confirmed that they were composed of an alloy with a polyamide resin as the sea phase (matrix) and an elastomer as the island phase (domain). Further, when the sea phase and island phase were examined by a scanning electron microscope and energy dispersive X-ray spectroscopy, it was confirmed that in Examples 1 to 7, sulfur-based compound 1 was unevenly distributed in the sea phase.

[0053] On the other hand, the hoses in the comparative examples showed poor hydrolysis resistance.

Industrial Applicability

[0054] The refrigerant transport hose of the present invention is suitably used for transporting refrigerants such as R-1234yf refrigerant which tends to be acidic, as well as carbon dioxide, chlorofluorocarbons, alternative chlorofluorocarbons, propane, water and other refrigerants used in air conditioners, radiators, etc. And the refrigerant transport hose is preferably used not only for automobiles but also for other transport machines (industrial transport vehicles such as airplanes, forklifts, excavators, cranes, etc., railway vehicles, etc.) and vending machines, etc.

Explanation of Signs

[0055] 1 Innermost layer 2 Rubber layer

Claims

1. A refrigerant transport hose comprising a tubular innermost layer and a rubber layer provided on the outer periphery of the innermost layer, wherein the polymer for the innermost layer is a blend polymer (A) composed of the following component (A-1) and component (A-2) with the following component (A-1) as the main component, the innermost layer contains the following component (B) in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the blend polymer (A), and is made of an alloy in which an island phase of the following component (A-2) is dispersed in a sea phase of the following component (A-1), a refrigerant transport hose. (A-1) An aliphatic polyamide resin. (A-2) A polyolefin-based elastomer. (B) A sulfur-based compound having a molecular structure represented by the following formula (1) in one molecule. 【Chemical 1】

2. The refrigerant transport hose according to claim 1, wherein the component (A-1) in the innermost layer is at least one aliphatic polyamide resin selected from the group consisting of polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, and polyamide 1010.

3. The refrigerant transport hose according to claim 1 or 2, wherein in the innermost layer, the component (B) is unevenly distributed in the sea phase of the component (A-1).

4. Furthermore, the refrigerant transport hose according to any one of claims 1 to 3, wherein the innermost layer contains the following component (C). (C) An aromatic amine compound.

5. The refrigerant transport hose according to claim 4, wherein the component (C) is 2-mercaptobenzimidazole.

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