Resin composition and hose

Abstract

The purpose of the present invention is to provide a resin composition having good oil resistance, adhesiveness with a resin member, and excellent durability. In order to solve this problem, this resin composition contains a polyamide, an olefin elastomer, and a compound having a piperidine structure, and is characterized in that the compound having the piperidine structure has repeating units including the piperidine structure and has a molecular weight of 1000-5000, and the content of the compound having the piperidine structure is 100 parts by mass per 100 parts by mass of the total content of the polyamide and the olefin elastomer. And the content of the compound having a piperidine structure is 0.1-6 parts by mass.

Description

Technical Field

[0001] The present disclosure relates to a resin composition and a hose. Background Art

[0002] A refrigerant delivery hose is a component used in vehicle air conditioning systems and other applications. Since fluorine-based refrigerants and lubricating oil flow inside the refrigerant delivery hose, high gas barrier properties are required from both performance and environmental perspectives. Therefore, the material forming the innermost surface layer is usually a polyamide resin layer, which provides excellent gas barrier properties and excellent vibration durability, including impact resistance performance and the like. An inner tube rubber layer is provided on this layer, and a reinforcing yarn layer made of organic fibers such as PET is provided on the inner tube rubber layer. Finally, a rubber layer made of weather-resistant rubber such as EPDM is provided (as disclosed in Patent Document 1 or other documents).

[0003] However, the above polyamide resin is prone to deterioration due to refrigerants such as Freon and oil from the compressor. Even when an olefin-based elastomer is used as the material for the innermost surface layer, this deterioration problem has not been solved, highlighting the need for further improvement in durability.

[0004] For example, if even a trace amount of acidic components are present in the air conditioning system, the polyamide resin composition may undergo significant deterioration under high-temperature and high-pressure operating conditions, which may render them unsuitable for use. Such acidic components may include extreme pressure additives found in the compressor oil sealed together with the refrigerant. Therefore, depending on the type of oil used in the air conditioning system and environmental conditions, conventional refrigerant delivery hoses may not achieve practical durability and become unusable.

[0005] To prevent such deterioration and enhance the durability of the innermost surface layer, techniques involving adding an inorganic acid scavenger to the polyamide resin composition have been developed.

[0006] For example, Patent Document 1 discloses a technique in which one or more metal compounds selected from the group consisting of hydroxides, oxides, and carbonates of divalent or trivalent metals are included in a refrigerant delivery hose having a gas barrier layer made of a polyamide resin composition.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] PTL 1: JP 2007-15245A

[0010] PTL 2: JP 2010-249316 A Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] According to the technology in PTL 1, deterioration of the gas barrier layer caused by the refrigerant and the compressor oil is prevented, thereby improving the durability of the refrigerant delivery hose.

[0013] However, in the technology of PTL 1, since the resin composition forming the innermost surface layer contains an inorganic acid scavenger, there are problems such as a decrease in moldability and a decrease in adhesiveness to the inner tube rubber due to uneven dispersion of the inorganic acid scavenger in the resin composition. In addition, there is a concern that water may be generated by the acid scavenger when capturing the acid, which may hinder the full exertion of the hydrolysis inhibition effect, and further improvement in durability is desired. Alternatively, a technique of using an organic acid scavenger as the acid scavenger can also be considered. However, in this case, there is a concern that the oil resistance of the innermost surface layer may decrease.

[0014] Therefore, an object of the present invention is to provide a resin composition having good adhesiveness to a rubber member, good oil resistance, and excellent durability.

[0015] In addition, another object of the present invention is to provide a hose having good adhesiveness between the innermost surface layer and the inner tube rubber and good oil resistance, in which deterioration caused by the refrigerant or oil is suppressed, and excellent durability is obtained.

[0016] Means for Solving the Problems

[0017] The present inventors have conducted extensive research to solve the above problems, and as a result, have found that by introducing a compound having a certain piperidine structure into the resin composition in addition to polyamide and an olefin-based elastomer and limiting its content within a certain range, it is possible to maintain good adhesiveness to a rubber member while capturing acid and suppressing hydrolysis. This has achieved excellent durability and also improved oil resistance.

[0018] The gist of the present disclosure for solving the above problems is as follows.

[0019] The resin composition of the present disclosure contains polyamide, an olefin-based elastomer, and a compound having a piperidine structure,

[0020] The compound having a piperidine structure has a repeating unit containing a piperidine structure and a molecular weight of 1000 to 5000, and

[0021] The content of the compound having a piperidine structure is 0.1 to 6 parts by mass with respect to 100 parts by mass of the total content of polyamide and the olefin-based elastomer.

[0022] By having the above characteristics, excellent adhesiveness to a rubber member, good oil resistance, and excellent durability can be achieved.

[0023] In addition, in the resin composition of the present disclosure, the content ratio of polyamide to olefin-based elastomer (polyamide / olefin-based elastomer) is preferably 80 / 20 to 50 / 50. This is because the barrier property, flexibility, and impact resistance are in good balance.

[0024] Furthermore, in the resin composition of the present disclosure, the olefin-based elastomer is preferably selected from the group consisting of ethylene-butene copolymers, EEA, EPR, and EPDM and their derivatives. This is because the flexibility and impact resistance can be further improved without causing a decrease in the barrier property and other properties.

[0025] In addition, in the resin composition of the present disclosure, the compound having a piperidine structure preferably has more than 4 methyl groups in the piperidine structure. This is because even better durability and oil resistance can be achieved.

[0026] Furthermore, in the resin composition of the present disclosure, the compound having a piperidine structure preferably contains at least 2,2,6,6-tetramethylpiperidine in the piperidine structure. This is because even better durability and oil resistance can be achieved.

[0027] Furthermore, in the resin composition of the present disclosure, the compound having a piperidine structure preferably further contains a triazine structure in the repeating unit. This is because even better durability and oil resistance can be achieved.

[0028] In addition, in the resin composition of the present disclosure, it is preferable to use the composition for the innermost surface layer of a hose, and more preferably the hose is a refrigerant delivery hose. This is because the improved effects of durability and oil resistance are significantly exhibited.

[0029] The hose of the present disclosure contains the above-mentioned resin composition of the present disclosure.

[0030] By having the above characteristics, excellent adhesion between the innermost surface layer and the inner tube rubber and good oil resistance can be achieved, and deterioration caused by refrigerant and oil can be suppressed, thereby achieving excellent durability as well.

[0031] Effects of the Invention

[0032] According to the present disclosure, a resin composition having good adhesion to a rubber member, good oil resistance, and excellent durability can be provided.

[0033] Furthermore, according to the present disclosure, a hose can be provided in which the adhesion between the innermost surface layer and the inner tube rubber is good and the oil resistance is good, and deterioration caused by refrigerant or oil is suppressed, resulting in excellent durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the drawings:

[0035] Figure 1A perspective view schematically showing an embodiment of the hose of the present disclosure. Detailed Description

[0036] Embodiments of the present disclosure are described below. These descriptions are provided for the purpose of exemplifying the present disclosure and do not limit the present disclosure in any way. Additionally, in the present disclosure, two or more embodiments can be arbitrarily combined.

[0037] <Resin Composition>

[0038] The resin composition of the present disclosure contains a polyamide, an olefin-based elastomer, and a compound having a piperidine structure.

[0039] Hereinafter, each component constituting the resin composition of the present invention is described.

[0040] (Polyamide)

[0041] The resin composition of the present disclosure contains a polyamide.

[0042] By including a polyamide as a main component, the gas barrier property and refrigerant barrier property can be improved.

[0043] The polyamide is a polyamide resin mainly containing amino acids, lactams, or diamines and dicarboxylic acids as main constituent components. Specific examples of these constituent components include lactams such as ε-caprolactam, heptalactam, and ω-laurolactam; amino acids such as ε-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid; diamines such as tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,2,4- / 2,4,4-trimethylhexamethylene diamine, 5-methylnonamethylene diamine, m-xylene diamine, p-xylene diamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(p-aminocyclohexyl)methane, bis(p-aminocyclohexyl)propane, isophorone diamine; and dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and dimer acid. These constituent components can be used alone or as a mixture of two or more for polymerization, and the resulting polyamide resin can be a homopolymer or a copolymer.

[0044] Preferred polyamide resins include, for example, polycaprolactam (nylon 6), polyhexamethylene adipamide (nylon 66), polybutylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polyhexamethylene adipamide / terephthalic acid hexamethylene diamine copolymer (nylon 66 / 6T), and polycaprolactam / polyhexamethylene adipamide copolymer (nylon 6 / 66). These polyamide resins can be used alone or as a mixture of two or more.

[0045] The degree of polymerization of the polyamide is not particularly limited, and any polyamide having a relative viscosity (hereinafter sometimes simply referred to as "relative viscosity") in the range of 1.5 to 5.0 at 25°C in a sulfuric acid solution having a concentration of 1 wt% can be arbitrarily used.

[0046] In addition, the polyamide may have an end group concentration, which is adjusted by adding one or more monocarboxylic acid compounds and / or dicarboxylic acid compounds or monoamine compounds and / or diamine compounds to the polyamide at any stage.

[0047] It should be noted that the content of the polyamide in the resin composition of the present disclosure is not particularly limited and can be appropriately adjusted according to the desired properties. For example, from the viewpoint of improving the barrier properties of the resin composition, it is preferable that the polyamide accounts for 50% by mass or more, more preferably 55% by mass or more, of the entire resin composition.

[0048] (Olefin-based elastomer)

[0049] The resin composition of the present disclosure further contains an olefin-based elastomer in addition to the polyamide. By including the olefin-based elastomer, not only can barrier properties be imparted, but also flexibility and impact resistance can be imparted.

[0050] Here, examples of the olefin-based elastomer include, for example, ethylene-butene copolymer, EPR (ethylene-propylene copolymer), modified ethylene-butene copolymer, EEA (ethylene-ethyl acrylate copolymer), modified EEA, modified EPR, modified EPDM (ethylene-propylene-diene terpolymer), ionomer, α-olefin copolymer, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butene-styrene copolymer), halogenated isobutene-p-methylstyrene copolymer, ethylene-acrylic acid modified polymer, ethylene-vinyl acetate copolymer, acid-modified forms thereof, and mixtures mainly composed of these. They can be used alone or in combination of two or more.

[0051] Among the above olefin-based elastomers, the olefin-based elastomer is preferably selected from the group consisting of ethylene-butene copolymer, EEA, EPR, and EPDM, and derivatives thereof. This is because flexibility and impact resistance can be further improved without causing a decrease in barrier properties and other properties.

[0052] In particular, an olefin-based elastomer modified with an acid anhydride such as maleic anhydride, an alkyl ester of acrylic acid such as glycidyl methacrylate, an epoxy type, and a modified form thereof is preferred as the olefin-based elastomer because they can form a fine alloy structure with the polyamide resin as the base polymer.

[0053] The content of the olefin-based elastomer in the resin composition of the present disclosure is not particularly limited. However, if the amount is too low, the improvement effects of flexibility and impact resistance provided by the olefin-based elastomer cannot be fully obtained, and if the amount is too high, the gas barrier property decreases. Therefore, the content is preferably 10% by mass or more, and more preferably 20% by mass or more.

[0054] In addition, the content ratio of polyamide to olefin-based elastomer (polyamide / olefin-based elastomer) in the resin composition of the present disclosure is preferably 80 / 20 to 40 / 60, more preferably 75 / 25 to 50 / 50, and particularly preferably 70 / 30 to 55 / 45 in terms of mass ratio. By setting the polyamide / olefin-based elastomer ratio within the above range, the gas barrier property, flexibility, and impact resistance can be well balanced at a higher level. If the content ratio of polyamide is too low, the gas barrier property decreases, and if the content ratio of the olefin-based elastomer becomes too low, there is a risk of decreased flexibility and impact resistance. Therefore, the above range is determined.

[0055] In the case of using a modified elastomer such as an acid-modified elastomer as the olefin-based elastomer, the effect of not requiring low specific energy and high mixing technology during kneading (dispersion) is achieved. However, if the blending amount is too high, gelation of the resin will occur, resulting in appearance defects such as surface roughness (fish eyes) during extrusion. Therefore, when using a modified elastomer as the olefin-based elastomer, the content of the modified elastomer in the polyamide resin composition is preferably 40% by mass or less, for example, 5 to 40% by mass. In particular, in the present disclosure, a composition in which 40 to 100% by mass of the olefin-based elastomer is an acid-modified elastomer can be preferably used.

[0056] In addition, in order to ensure the compatibility between polyamide and olefin-based elastomer, in other words, in order to achieve a good dispersion state, at least a part of the elastomer is preferably modified with maleic anhydride or the like. In order to obtain a good dispersion morphology, the average acid value (acid modification rate) of the whole elastomer used is preferably 0.8 mgCH 3 ONa / g or more.

[0057] In addition, as the acid value of the elastomer increases, the dispersion morphology improves. However, as the acid value increases, the viscosity of the obtained polyamide resin composition increases, impairing the molding processability. Therefore, in order to reduce the increase in viscosity caused by the increase in acid value, within the range where a good dispersion state can be obtained, the acid value of the elastomer is preferably as low as possible, and the average acid value of the whole elastomer used is preferably 7.5 mgCH 3 ONa / g or less.

[0058] In addition, even when the average acid value is the same, when the acid value of the modified elastomer contained in the elastomer used is high, even if the average acid value decreases, gel-like foreign substances may still occur by mixing such a modified elastomer with an unmodified elastomer, and the gel-like foreign substances are presumed to be caused by local overreaction during extrusion. Therefore, the acid value of the modified elastomer used is preferably 15.0 mgCH 3 ONa / g or less.

[0059] In this way, although including an olefin-based elastomer in the resin composition improves flexibility, impact resistance, etc., a decrease in gas barrier properties is inevitable. However, by adopting a fine alloy structure between the polyamide and the elastomer, particularly by dispersing the island phase of the elastomer in the sea phase of the polyamide and further dispersing the polyamide resin in a scattered manner in the island phase of the elastomer, a decrease in gas barrier properties due to the inclusion of the elastomer can be suppressed, which is preferable.

[0060] (Compound having a piperidine structure)

[0061] In addition, the resin composition of the present disclosure contains a compound having a piperidine structure in addition to the above polyamide and olefin-based elastomer.

[0062] Here, the compound having a piperidine structure has a repeating unit containing a piperidine structure and a molecular weight of 1000 to 5000.

[0063] Such a compound having a piperidine structure can neutralize acids. Therefore, the resin composition of the present disclosure inhibits hydrolysis and can achieve excellent durability and oil resistance. In addition, since the compound having a piperidine structure exhibits high dispersibility in the resin composition and does not produce water as a byproduct when neutralizing acids, compared with the case of using an inorganic acid scavenger, it provides excellent durability and also prevents a decrease in the adhesiveness to the rubber component.

[0064] The reason for limiting the molecular weight of the compound having a piperidine structure to 1000 to 5000 is that by setting the molecular weight to 1000 or more, even if a part of the molecule of the compound having a piperidine structure splits, the above effects of inhibiting hydrolysis and improving durability can be maintained. In addition, by setting the molecular weight to 5000 or less, a decrease in the processability of the resin composition can be prevented. From a similar viewpoint, the molecular weight of the compound having a piperidine structure is preferably 1500 to 4000, more preferably 2000 to 3500.

[0065] In addition, the piperidine structure refers to a structure in which one carbon atom in six methylenes of cyclohexane is replaced by nitrogen and one hydrogen is removed, and the piperidine structure may have various substituents.

[0066] Compounds having a piperidine structure have repeating units containing a piperidine structure, and when used together with the above polyamide and olefin-based elastomer, they can impart excellent durability and oil resistance.

[0067] Here, the compound having a piperidine structure preferably contains four or more methyl groups in the piperidine structure. This is to suppress gelation caused by reaction with the carboxylic acid at the end of the polyamide.

[0068] Examples of piperidines having four or more methyl groups include, for example, 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentamethylpiperidine, and the following compounds.

[0069] [Chemical Formula 1]

[0070]

[0071] In addition, the compound having a piperidine structure preferably further contains a triazine structure in the repeating unit. This is because even better durability and oil resistance can be achieved.

[0072] Examples of compounds containing both a piperidine structure and a triazine structure in the repeating unit include, for example, the following compounds.

[0073] [Chemical Formula 2]

[0074]

[0075] [Chemical Formula 3]

[0076]

[0077] In the resin composition of the present disclosure, the content of the compound having a piperidine structure is 0.1 to 6 parts by mass relative to 100 parts by mass of the total content of the polyamide and the olefin-based elastomer. When the content of the compound having a piperidine structure is 0.1 part by mass or more relative to 100 parts by mass of the total content of the polyamide and the olefin-based elastomer, a sufficient durability improvement effect can be obtained. When the content is 6 parts by mass or less relative to 100 parts by mass of the total content of the polyamide and the olefin-based elastomer, a decrease in the adhesiveness to the rubber component can be suppressed.

[0078] From a similar viewpoint, the content of the compound having a piperidine structure is preferably 0.3 to 5 parts by mass, more preferably 0.4 to 4.5 parts by mass, and even more preferably 0.5 to 4 parts by mass relative to 100 parts by mass of the total content of the polyamide and the olefin-based elastomer.

[0079] (Other Components)

[0080] The resin composition of the present disclosure may further contain additives (other components) such as lubricants, antistatic agents, anti-aging agents, antioxidants, colorants, nucleating agents, fillers, reinforcing materials, heat-resistant agents, and light-resistant agents as needed.

[0081] <Hose>

[0082] Next, the hose of the present disclosure will be described.

[0083] The hose of the present disclosure contains the resin composition of the present disclosure described above.

[0084] By providing a member made of the resin composition of the present disclosure, good adhesiveness to rubber parts and good oil resistance can be achieved, and hydrolysis can be suppressed, thereby improving durability.

[0085] The hose of the present disclosure is a refrigerant delivery hose, and the resin composition of the present disclosure described above is preferably used as the innermost surface layer of the hose.

[0086] This is because good adhesiveness between the inner tube rubber and the innermost surface layer and good oil resistance can be maintained, and deterioration caused by refrigerants and oils can be suppressed, so that the durability is excellent.

[0087] Here, Figure 1 is a schematic perspective view showing an embodiment of the refrigerant delivery hose of the present disclosure. The innermost surface layer 2 of the refrigerant delivery hose 1 is made of the resin composition of the present disclosure described above, and an inner layer rubber layer 3 is formed around its outer periphery. A first reinforcing yarn layer 4, an intermediate rubber layer 5, a second reinforcing yarn layer 6, and an outer coating rubber layer 7 are formed in sequence. The inner diameter of the hose 1 is not particularly limited, but is usually about 6 to 20 mm, particularly about 8 to 19 mm.

[0088] The innermost surface layer 2 is made of the resin composition of the present disclosure. The composition of the resin composition of the present disclosure is as described above. From the viewpoint of gas barrier properties, the thickness of such an innermost surface layer 2 is preferably high, but an increase in thickness reduces the flexibility of the hose. Therefore, the thickness of the innermost surface layer 2 can be set to about 50 to 500 μm, particularly about 100 to 450 μm.

[0089] It should be noted that the refrigerant delivery hose of the present disclosure may further include an inner rubber layer (not shown) formed on the inner side of the innermost surface layer 2.

[0090] As the rubber for forming the inner rubber layer 3 and the outer coating rubber layer 7, the rubbers commonly used include butyl rubber (IIR), chlorinated butyl rubber (Cl-IIR), chlorinated polyethylene, chlorosulfonated polyethylene, brominated butyl rubber (Br-IIR), isobutene-bromo-p-methylstyrene copolymer, EPR (ethylene-propylene copolymer), EPDM (ethylene-propylene-diene terpolymer), NBR (nitrile rubber), CR (neoprene), hydrogenated NBR, acrylic rubber, ethylene-acrylic rubber (AEM), blends of two or more of these rubbers, or blends with polymers having one of these rubbers as the main component. Butyl-based rubbers or EPDM-based rubbers are preferably used. Commonly used fillers, processing aids, anti-aging agents, vulcanizing agents, vulcanization accelerators and other compounding ingredients can be blended into these rubbers.

[0091] It should be noted that the rubbers of the inner rubber layer 3 and the outer coating rubber layer 7 can be of the same type or different types.

[0092] In addition, there is no particular limitation on the rubber of the intermediate rubber layer 5 as long as it has good adhesiveness to the inner rubber layer 2 and the outer coating rubber layer 7.

[0093] In addition, an adhesive can be inserted between the inner rubber layer 3 and the innermost surface layer 2.

[0094] From the viewpoint of flexibility, the thickness of the inner rubber layer 3 is preferably about 0.5 to 4 mm. The thickness of the intermediate rubber layer 5 is preferably about 0.1 to 0.6 mm, and the thickness of the outer coating rubber layer 7 is preferably about 0.5 to 2 mm.

[0095] The first reinforcing yarn layer 4 is formed by helically winding reinforcing yarns, and the second reinforcing yarn layer 6 is formed by helically winding reinforcing yarns in the opposite direction to the reinforcing yarns of the first reinforcing yarn layer 4.

[0096] There is no particular limitation on the material of these reinforcing yarns as long as commonly used materials are adopted. Generally, polyester, wholly aromatic polyester, nylon, vinylon, rayon, aramid, polyarylate, polyethylene naphthalate and twisted yarns of these materials are used.

[0097] The refrigerant delivery hose of the present disclosure can be manufactured according to conventional methods. For example, the materials of the gas barrier layer 2 and the inner rubber layer 3 are extruded on a mandrel and laminated to a predetermined thickness, the reinforcing yarn layer 4 is wound, the intermediate rubber layer 5 is extruded and laminated, the reinforcing yarn layer 6 is wound, and then the outer coating rubber layer 7 is extruded and laminated, and then vulcanization is carried out at 140 to 170 °C for 30 to 120 minutes to manufacture the hose.

[0098] The compounds described in this specification may be partially or wholly derived from fossil resources, may be derived from biological resources such as plant resources, or may be derived from renewable resources. In addition, they may be derived from a mixture of any two or more of fossil resources, biological resources, and renewable resources.

[0099] Examples

[0100] The following examples are provided to further explain the present disclosure; however, these examples are for illustrative purposes and do not limit the present disclosure in any way. In the examples, unless otherwise specified, amounts are expressed in parts by mass.

[0101] (Samples 1 - 13)

[0102] According to the formulations summarized in Table 1, various samples of the resin composition were prepared by kneading using a twin-screw kneader manufactured by Toyo Seiki Seisaku-sho, Ltd. at 240 °C (above the melting point of the polyamide resin).

[0103] It should be noted that the content of each component in Table 1 is expressed in parts by mass relative to the total content (100 parts by mass) of the polyamide and the olefin-based elastomer.

[0104] (Evaluation)

[0105] The following evaluations were performed on the various samples of the obtained resin composition. The evaluation results are summarized in Table 1.

[0106] (1) Initial elongation at break (Eb)

[0107] After preparing test pieces from the various samples of the resin composition, a tensile testing machine manufactured by Shimadzu Corporation was used to elongate the specimens at a speed of 200 mm / min to measure the elongation at break (%).

[0108] The measurement results of the elongation at break (Eb) are summarized in Table 1. The higher this value, the better the evaluation of the initial elongation at break.

[0109] (2) Retention rate of elongation at break (ΔEb) after refrigerant and oil test

[0110] After preparing test pieces from the various samples of the resin composition, a refrigerant and oil test was performed under the following conditions.

[0111] Subsequently, a tensile testing machine manufactured by Shimadzu Corporation was used to elongate the specimen at a speed of 200 mm / min to measure the elongation at break (%). After the measurement, the ratio of the obtained value to the initial elongation at break (Eb) was calculated (elongation at break after refrigerant and oil tests / initial elongation at break × 100%), and this ratio was maintained as the elongation at break retention rate (ΔEb) after refrigerant and oil tests.

[0112] The calculation results of the elongation at break retention rate (ΔEb) after refrigerant and oil tests are summarized in Table 1. The results show excellent durability and oil resistance.

[0113] (Refrigerant and oil tests)

[0114] A tensile test piece with a thickness of 0.35 mm was placed in a pressure-resistant container, and 47 g of polyalkylene glycol with a water content adjusted to 2000 ppm was added. Then, the pressure-resistant container was frozen for 1 hour and decompressed for 3 minutes. Next, 47 g of R-134a was added as a refrigerant, and the container was placed at 150 °C for 1 week.

[0115] [Table 1]

[0116]

[0117] *1: Total amount of nylon 6 containing at least "UBE Nylon 1011FB"

[0118] *2: "Tafmer MH7010" manufactured by Mitsui Chemicals, Inc.

[0119] *3: "Tafmer A-1050S" manufactured by Mitsui Chemicals, Inc.

[0120] *4: Total amount of antioxidants containing "Adekstab AO-80", "Adekstab CDA-10", and "SUMILIZER TP-D"

[0121] *5: "Chimassorb 2020FDL" manufactured by BASF Japan Ltd.

[0122] *6: "Chimassorb 944FDL" manufactured by BASF Japan Ltd.

[0123] *7: Reactive polystyrene containing an oxazoline group, "Epocross RPS" manufactured by Nippon Shokubai Co., Ltd.

[0124] *8: Carbodilite, "HMV-5CA-LC" manufactured by Nisshinbo Chemical Inc.

[0125] *9: "OGSOL MF-11" manufactured by Osaka Gas Chemical Co., Ltd.

[0126] *10: "Light Amide WH-510K" manufactured by KYOEISHACHEMICAL Co., LTD.

[0127] *11: "Bal-7220" manufactured by Marubishi Oil Chemical Corporation

[0128] It can be understood from the results in Table 1 that the samples in the examples showed excellent elongation at break retention rates after the refrigerant and oil tests compared to the samples in the comparative examples.

[0129] Industrial Applicability

[0130] According to the present disclosure, a resin composition having good adhesiveness to a rubber member, good oil resistance, and excellent durability can be provided.

[0131] In addition, according to the present disclosure, a hose having good adhesiveness between the innermost surface layer and the inner tube rubber, good oil resistance, and excellent durability, which suppresses deterioration caused by a refrigerant or oil, can be provided.

[0132] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)]

[0133] The SDGs were proposed to achieve a sustainable society. One embodiment of the present disclosure can be considered a technology that contributes to goals such as "Goal 7: Affordable and Clean Energy", "Goal 12: Responsible Consumption and Production", and "Goal 13: Climate Action".

[0134] Explanation of Reference Numerals

[0135] 1 Refrigerant delivery hose

[0136] 2 Innermost surface layer

[0137] 3 Inner rubber layer

[0138] 4, 6 Reinforcing yarn layer

[0139] 5 Intermediate rubber layer

[0140] 7 Outer coating rubber layer

Claims

1. A resin composition comprising a polyamide, an olefin-based elastomer, and a compound having a piperidine structure, wherein the compound having a piperidine structure has a repeating unit containing a piperidine structure and a molecular weight of 1,000 to 5,000, and the content of the compound having a piperidine structure is 0.1 to 6 parts by mass based on 100 parts by mass of the total content of the polyamide and the olefin-based elastomer.

2. The resin composition according to claim 1, wherein the content ratio of the polyamide to the olefin-based elastomer, i.e., polyamide / olefin-based elastomer, is 80 / 20 to 40 / 60.

3. The resin composition according to claim 1 or 2, wherein the olefin-based elastomer is at least one selected from the group consisting of ethylene-butene copolymers, EEA, EPR, and EPDM and their derivatives.

4. The resin composition according to claim 1 or 2, wherein the compound having a piperidine structure has more than 4 methyl groups in the piperidine structure.

5. The resin composition according to claim 1 or 2, wherein the compound having a piperidine structure contains at least 2,2,6,6-tetramethylpiperidine in the piperidine structure.

6. The resin composition according to claim 1 or 2, wherein the compound having a piperidine structure further contains a triazine structure in the repeating unit.

7. The resin composition according to claim 1 or 2, which is used for the innermost surface layer of a hose.

8. The resin composition according to claim 7, wherein the hose is a refrigerant delivery hose.

9. A hose comprising the resin composition according to claim 1 or 2.

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