Rubber composition for hoses and hoses

Abstract

The present invention provides a rubber composition that exhibits excellent resistance to compression set in the resulting rubber layer, good adhesion between the resin layer and the rubber layer, good adhesion between the rubber layer and the fiber reinforcement layer, and excellent strength retention between the rubber layer and the adjacent fiber reinforcement layer. [Solution] A rubber composition for hoses and a hose, comprising 30 to 100 parts by mass of one or more types of rubber X selected from the group consisting of brominated copolymer rubber of isomonoolefin and p-alkylstyrene, and halogenated butyl rubber (excluding chlorinated butyl rubber), and 0 to 70 parts by mass of one or more types of rubber Y selected from the group consisting of butyl rubber, chlorinated butyl rubber, and EPDM, wherein per 100 parts by mass of the rubber component, the composition contains 20 parts by mass or more of carbon black, 1.0 to 15 parts by mass of phenolic resin, and 0.1 to 1.0 parts by mass of magnesium oxide.

Description

[Technical Field]

[0001] This invention relates to a rubber composition for hoses and a hose. [Background technology]

[0002] Conventionally, a hose for transporting refrigerants (e.g., an air conditioner hose) is known, for example, in which the innermost layer is a resin layer containing polyamide or the like with low gas permeability, the innermost layer has a rubber layer formed from a rubber composition containing butyl rubber and a resin crosslinking agent (e.g., a phenolic resin), the rubber layer has a reinforcing layer formed from synthetic resin fibers or the like on top of the rubber layer, and the reinforcing layer has an outer tube on top of the reinforcing layer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2010 / 073375 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Hoses used for transporting refrigerants require high resistance to refrigerant permeability in the innermost layer to suppress leakage of internal fluids (e.g., fluorocarbon gases), as well as excellent resistance to compression set in the rubber layer and good adhesion between the innermost resin layer and the rubber layer above it. Furthermore, refrigerant transport hoses are required to have excellent adhesion between the rubber layer and the fiber reinforcement layer. Furthermore, refrigerant transport hoses require high strength in their fiber reinforcement layer in order to withstand high pressure. On the other hand, the required levels for compression set resistance of the rubber layer, adhesion between the innermost resin layer and the rubber layer above it, adhesion between the rubber layer and the fiber reinforcement layer, and high strength of the fiber reinforcement layer have been increasing in recent years. In this context, the present inventors prepared a rubber composition with reference to Patent Document 1 and evaluated it. They found that such a rubber composition has room for further improvement in at least one of the following aspects: the compression set resistance of the resulting rubber layer, the adhesion between the resin layer and the rubber layer, the adhesion between the rubber layer and the fiber reinforcement layer, and the strength retention of the rubber layer and the adjacent fiber reinforcement layer. The inventors believe that the strength of the rubber layer and the adjacent fiber reinforcement layer may not meet current requirements when the rubber layer is formed from a rubber composition containing a phenolic resin or a halogenated copolymer rubber of isomonoolefin and p-alkylstyrene, and the fiber reinforcement layer is formed from polyethylene terephthalate as reinforcing yarn. Because the polarity of the phenolic resin is similar to that of the reinforcing yarn (PET), it penetrates from the rubber layer into the reinforcing yarn, causing the yarn to swell, facilitating the penetration of moisture into the yarn, making hydrolysis more likely, and degrading the reinforcing yarn (fiber reinforcement layer). In addition, acids (e.g., bromic acid (HBr)) generated from the halogenated copolymer rubber of isomonoolefin and p-alkylstyrene degrade the reinforcing yarn (fiber reinforcement layer). The inventors believe that the swelling of the reinforcing yarn and degradation by acid as described above are the reasons why the strength of the rubber layer and the adjacent fiber reinforcement layer does not meet current requirements.

[0005] Therefore, the present invention aims to provide a rubber composition for hoses that exhibits excellent resistance to compression set in the resulting rubber layer, excellent adhesion between the resin layer and the rubber layer, excellent adhesion between the rubber layer and the fiber reinforcement layer, and excellent strength retention between the rubber layer and the adjacent fiber reinforcement layer. The present invention also aims to provide a hose. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the inventors of the present invention discovered that the desired effect can be obtained by including magnesium oxide in a specific range of amounts in the rubber composition, leading to the present invention. The present invention is based on the above findings, and specifically solves the above problems with the following configuration.

[0007] [1] A rubber component comprising 30 to 100 parts by mass of one or more types of rubber X selected from the group consisting of brominated copolymer rubbers of isomonoolefins and p-alkylstyrenes, and halogenated butyl rubber (excluding chlorinated butyl rubber), and having a content of 0 to 70 parts by mass of one or more types of rubber Y selected from the group consisting of butyl rubber, chlorinated butyl rubber, and EPDM, Carbon black 20 parts by mass or more, 1.0 to 15 parts by mass of phenolic resin, A rubber composition for hoses containing 0.1 to 1.0 parts by mass of magnesium oxide. [2] The rubber composition for hoses according to [1], wherein the halogenated butyl rubber is brominated butyl rubber. [3] The rubber composition for hoses according to [1] or [2], wherein the magnesium oxide content is 0.2 to 1.0 parts by mass per 100 parts by mass of the rubber component. [4] The rubber composition for hoses according to any one of [1] to [3], wherein the phenolic resin comprises an alkylphenol formaldehyde resin and / or a brominated alkylphenol formaldehyde resin, and the content of the phenolic resin is 1.0 to 10 parts by mass per 100 parts by mass of the rubber component. [5] The rubber composition for hoses according to any one of [1] to [4], further containing talc, wherein the amount of talc is 30 to 100 parts by mass per 100 parts by mass of the rubber component. [6] The rubber composition for hoses according to [5], wherein the talc content is 1 / 2 or less of the carbon black content. [7] The layers, in order from the innermost layer, are a resin layer, a first rubber layer, a fiber reinforcement layer, and a second rubber layer. The resin layer is adjacent to the first rubber layer, and the first rubber layer is adjacent to the fiber reinforcement layer. The above resin layer is a layer comprising a polyamide and a carboxyl group-containing modified polyolefin. The first rubber layer described above is a layer formed by a cured product of the rubber composition for hoses described in any one of [1] to [6], A hose in which the fiber reinforcing layer is a layer of polyethylene terephthalate fibers. [Advantages of the Invention]

[0008] According to the present invention, it is possible to provide a rubber composition for a hose, in which the obtained rubber layer has excellent compression set resistance, the adhesiveness between the resin layer and the rubber layer, the adhesiveness between the rubber layer and the fiber reinforcing layer, and the strength retention of the fiber reinforcing layer adjacent to the rubber layer. The present invention can provide a hose. [Brief Description of the Drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view showing an example of the hose of the present invention with each layer cut away. [Figure 2] FIG. 2 is a schematic perspective view showing another example of the hose of the present invention with each layer cut away. [Modes for Carrying Out the Invention]

[0010] The present invention will be described in detail below. In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In this specification, unless otherwise specified, each component is not particularly limited with respect to its production method. For example, conventionally known methods can be mentioned. In this specification, unless otherwise specified, each component can use the substances corresponding to the component alone or in combination of two or more. When the component contains two or more substances, the content of the component means the total content of the two or more substances. In this specification, when at least one of the compression set resistance of the obtained rubber layer, the adhesiveness between the resin layer and the rubber layer, the adhesiveness between the rubber layer and the fiber reinforcing layer, and the strength retention of the fiber reinforcing layer adjacent to the rubber layer is more excellent, it may be referred to as "the effects of the present invention are more excellent".

[0011] [Rubber Composition] The rubber composition for a hose of the present invention (the rubber composition of the present invention) is comprising 30 to 100 parts by mass of at least one type of rubber X selected from the group consisting of brominated copolymers of isomonoolefin and p-alkylstyrene, and halogenated butyl rubber (excluding chlorinated butyl rubber), with respect to 100 parts by mass of the rubber component, the content of at least one type of rubber Y selected from the group consisting of butyl rubber, chlorinated butyl rubber, and EPDM being 0 to 70 parts by mass, 20 parts by mass or more of carbon black, 1.0 to 15 parts by mass of a phenolic resin, and 0.1 to 1.0 parts by mass of magnesium oxide, and is a rubber composition for a hose.

[0012] Since the rubber composition of the present invention has such a configuration, it is considered that desired effects can be obtained. In the present invention, regarding the excellent maintainability of the strength of the fiber reinforcing layer adjacent to the rubber layer, magnesium oxide is contained in the rubber composition of the present invention in an amount within a specific range. Since the polarity of magnesium oxide is close to that of the phenolic resin, magnesium oxide attracts the phenolic resin in the rubber composition of the present invention, suppresses the penetration of the phenolic resin into the reinforcing yarn, and is presumed to delay the deterioration (for example, hydrolysis) of the reinforcing yarn. Further, it is presumed that magnesium oxide captures the acid generated from the halogenated copolymer rubber of isomonoolefin and p-alkylstyrene, thereby reducing the attack on the fiber reinforcing layer by the above acid. Next, regarding the compression set resistance, generally, the higher the crosslink density of the rubber obtained, the smaller the compression set. However, when a large amount of magnesium oxide is added to the rubber composition, magnesium oxide delays the crosslinking of the rubber, resulting in a low crosslink density and a deteriorated compression set. On the other hand, the rubber composition of the present invention contains magnesium oxide in an amount within a specific range, so that the crosslinking rate of the rubber can be adjusted within a range considering hose productivity, and the compression set of the rubber layer can be set to a level required for the hose, and it is presumed that the compression set resistance is excellent. Regarding the adhesion between the resin layer and the rubber layer, and the adhesion between the rubber layer and the fiber reinforcement layer, the crosslinking reaction of the rubber in the rubber composition of the present invention and the adhesion reaction between the rubber composition of the present invention and the resin layer or fiber reinforcement layer are competitive reactions. Therefore, it is presumed that by incorporating magnesium oxide into the rubber composition of the present invention, the crosslinking reaction rate in the rubber composition of the present invention can be controlled to an appropriate range in the competitive relationship between the crosslinking reaction and the adhesion reaction, thereby favoring the adhesion reaction between the rubber composition of the present invention and the resin layer and the fiber reinforcement layer. The following describes in detail each component contained in the rubber composition of the present invention.

[0013] [Rubber components] In the present invention, the rubber component includes one or more types of rubber X selected from the group consisting of brominated copolymer rubbers of isomonoolefin and p-alkylstyrene, and halogenated butyl rubber (excluding chlorinated butyl rubber). In the present invention, the content of rubber X in 100 parts by mass of the rubber component is 30 to 100 parts by mass. Furthermore, in the present invention, the content of one or more types of rubber Y selected from the group consisting of butyl rubber, chlorinated butyl rubber, and EPDM is 0 to 70 parts by mass in 100 parts by mass of the rubber component.

[0014] [Rubber X] In the present invention, rubber X is one or more selected from the group consisting of brominated copolymer rubbers of isomonoolefin and p-alkylstyrene, and halogenated butyl rubber (excluding chlorinated butyl rubber). From the viewpoint of achieving superior effects of the present invention (particularly the adhesion between the fiber-reinforced layer and / or the resin layer and the rubber layer), it is preferable that rubber X contains a brominated product of a copolymer rubber of isomonoolefin and p-alkylstyrene.

[0015] [Bromides of copolymer rubber of isomonoolefin and p-alkylstyrene (specific brominated compounds)] In the present invention, the brominated product of the copolymer rubber of isomonoolefin and p-alkylstyrene that rubber X may contain is not particularly limited. In this specification, the brominated product of the copolymer rubber of isomonoolefin and p-alkylstyrene is also referred to as a "specific brominated product." There are no particular restrictions on which of the repeating units constituting the specified brominated product are brominated. One preferred embodiment is that some of the repeating units of the above-mentioned copolymer rubber made of p-alkylstyrene are brominated. In other words, in the above case, the specified brominated product may have, for example, repeating units made of isomonoolefin, repeating units made of unbrominated p-alkylstyrene, and repeating units made of brominated p-alkylstyrene.

[0016] [Isomonoolefin] The isomonoolefin constituting the above-mentioned specific brominated material has a C at its terminus. * It is a hydrocarbon compound having a branched structure of -(CH3)2 and one double bond at another end. Note that if the isomonoolefin has 4 carbon atoms, then the above C * -(CH3)2 C * They can form a double bond.

[0017] • Number of carbon atoms From the viewpoint of achieving superior effects of the present invention, the carbon number of the isomonoolefin is preferably 4 to 7, and more preferably 4.

[0018] Examples of the above-mentioned isomonoolefins include isobutylene (isobutene, 2-methyl-1-propene), 3-methyl-1-butene (isopentene), 4-methyl-1-pentene (isohexene), and 5-methyl-1-hexene (isoheptene). Among the above isomonoolefins, isobutylene is preferred from the viewpoint of providing superior effects of the present invention.

[0019] [p-alkylstyrene] The p-alkylstyrene that constitutes a specific brominated compound is styrene having an alkyl group at the p-position. In the specific brominated product, one preferred embodiment is that a portion of the repeating units of the p-alkylstyrene are brominated at the alkyl group of the p-alkylstyrene.

[0020] Examples of alkyl groups that the above-mentioned p-alkylstyrene may possess include alkyl groups having 1 to 8 carbon atoms, such as methyl groups and ethyl groups. Among these, p-methylstyrene is preferred from the viewpoint of providing superior effects of the present invention.

[0021] (Content of repeating units containing bromine) From the viewpoint of achieving superior effects of the present invention, the content of repeating units having bromine that constitute the specific brominate is preferably 0.8 to 1.5 mol% relative to the total amount of repeating units constituting the specific brominate.

[0022] Examples of specific brominated materials include brominated isobutylene-co-p-methylstyrene rubber (BIMS).

[0023] (Halogenated butyl rubber) In the present invention, the halogenated butyl rubber that rubber X may contain is not particularly limited. However, in the present invention, chlorinated butyl rubber is excluded from the halogenated butyl rubber.

[0024] • Brominated butyl rubber Examples of halogenated butyl rubber include brominated butyl rubber. If rubber X contains halogenated butyl rubber, the halogenated butyl rubber is preferably brominated butyl rubber from the viewpoint of providing superior effects of the present invention.

[0025] When halogenated butyl rubber includes brominated butyl rubber, the brominated butyl rubber is not particularly limited as long as it is a butyl rubber containing bromine. Examples include conventionally known types. Furthermore, the bromine content in the brominated butyl rubber is not particularly limited and can be, for example, 1 to 2.5% by mass. The isoprene content in the brominated butyl rubber can be, for example, 0.6 to 3.0 mol% of the total amount of repeating units constituting the brominated butyl rubber.

[0026] [Rubber X content] In the present invention, the rubber component contains 30 to 100 parts by mass of rubber X per 100 parts by mass of the rubber component. That is, the content of rubber X (total content if there are two or more types of rubber X; the same applies hereinafter) is 30 to 100 parts by mass per 100 parts by mass of the rubber component. From the viewpoint of achieving superior effects of the present invention (particularly the adhesion between the fiber-reinforced layer and / or the resin layer and the rubber layer), the content of rubber X is preferably 60 to 100 parts by mass, more preferably 90 to 100 parts by mass, and even more preferably 100 parts by mass, per 100 parts by mass of the rubber component.

[0027] [Rubber Y] In the present invention, the content of one or more types of rubber Y selected from the group consisting of butyl rubber, chlorinated butyl rubber, and EPDM is 0 to 70 parts by mass per 100 parts by mass of rubber component.

[0028] (Butyl rubber) The butyl rubber that may be contained in the rubber composition of the present invention is not particularly limited. For example, a general isobutylene-isoprene copolymer rubber can be used. The isoprene content in butyl rubber can be, for example, 0.6 to 3.0 mol% of the total amount of repeating units constituting the butyl rubber. Furthermore, butyl rubber does not contain halogens.

[0029] (Chlorinated butyl rubber) The chlorinated butyl rubber that may be contained in the rubber composition of the present invention is not particularly limited as long as it is a butyl rubber containing chlorine. Examples include conventionally known types. Furthermore, the chlorine content in the chlorinated butyl rubber is not particularly limited and can be, for example, 1 to 2.5% by mass. The isoprene content in the chlorinated butyl rubber can be, for example, 0.6 to 3.0 mol% of the total amount of repeating units constituting the chlorinated butyl rubber.

[0030] (EPDM) The EPDM (ethylene-propylene-diene rubber) that may be contained in the rubber composition of the present invention is not particularly limited as long as it is a copolymer of ethylene, propylene, and a diene component as a third component. Examples include conventionally known materials. EPDM has a double bond derived from the above-mentioned diene component. In this invention, EPDM corresponds to the rubber component. Examples of diene components that make up EPDM include non-diene monomers such as ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), and dicyclopentadiene (DCP), with ENB being preferred among them. The content of the diene component in EPDM is preferably 7 to 11% by mass.

[0031] [Rubber Y content] In the present invention, the content of rubber Y in 100 parts by mass of the rubber component is 0 to 70 parts by mass. When the rubber composition of the present invention contains rubber Y, the content of rubber Y (total content if there are two or more types of rubber Y; the same applies hereinafter) should be greater than 0 parts by mass and 70 parts by mass or less in 100 parts by mass of the rubber component. From the viewpoint of achieving superior effects of the present invention (particularly the adhesion between the fiber-reinforced layer and / or the resin layer and the rubber layer), the content of rubber Y is preferably 0 to 40 parts by mass, more preferably 0 to 10 parts by mass, and even more preferably 0 parts by mass, per 100 parts by mass of the rubber component.

[0032] (Other types of rubber) If the total content of rubber X and rubber Y is less than 100 parts by mass per 100 parts by mass of the rubber component, the rubber component may further contain other rubbers other than rubber X and rubber Y. The other rubbers are not particularly limited.

[0033] [Carbon Black] The rubber composition of the present invention contains carbon black (CB). The CB is not particularly limited; for example, conventionally known CBs can be used.

[0034] From the viewpoint of achieving superior effects of the present invention, CB preferably contains carbon black of HAF (High Abration Furnace), FTF (Fine Thermal Furnace), GPF (General Purpose Furnace), or SRF (Semi-Reinforcing Furnace). From the viewpoint of achieving superior effects of the present invention and facilitating mixing of the rubber composition, it is even more preferable that CB contains carbon black of FTF and / or SRF.

[0035] [Carbon black content] In the present invention, the carbon black content is 20 parts by mass or more per 100 parts by mass of the above rubber component. From the viewpoint of achieving superior effects of the present invention, the carbon black content is preferably 40 to 200 parts by mass, more preferably 80 to 150 parts by mass, and even more preferably 100 to 150 parts by mass, per 100 parts by mass of the rubber component.

[0036] [Phenolic resin] The rubber composition of the present invention contains a phenolic resin. The phenolic resin contained in the rubber composition of the present invention can function, for example, as a crosslinking agent for rubber or as a crosslinking aid for specific brominated compounds. The above-mentioned phenolic resin may be alkylated or halogenated, for example. Examples of phenolic resins contained in the rubber composition of the present invention include alkylphenol resins and halogenated alkylphenol resins, and more specifically, alkylphenol formaldehyde resins and brominated alkylphenol formaldehyde resins.

[0037] From the viewpoint of achieving superior effects of the present invention, the phenolic resin preferably contains alkylphenol formaldehyde resin and / or brominated alkylphenol formaldehyde resin, and more preferably contains brominated alkylphenol formaldehyde resin. Examples of alkylphenol formaldehyde resins include condensates of alkylphenol and formaldehyde. Note that alkylphenol formaldehyde resins do not include brominated alkylphenol formaldehyde resins. Examples of brominated alkylphenol formaldehyde resins include condensates of brominated alkylphenol and formaldehyde.

[0038] [Phenolic resin content] In the present invention, the content of phenolic resin (total content if there are two or more types of phenolic resins; the same applies hereinafter) is 1.0 to 15 parts by mass per 100 parts by mass of the above rubber component. From the viewpoint of achieving superior effects of the present invention, the content of the phenolic resin relative to 100 parts by mass of the rubber component is preferably 1 to 10 parts by mass, and more preferably 2 to 7 parts by mass.

[0039] [Magnesium Oxide] The rubber composition of the present invention contains magnesium oxide (MgO). The magnesium oxide contained in the rubber composition of the present invention has a BET specific surface area of ​​20 m², from the viewpoint of achieving superior effects of the present invention. 2 It is preferable that the amount is 1 / g or more, and the BET specific surface area of ​​magnesium oxide is 100 to 200 m². 2 It is more preferable that it be / g. The BET specific surface area of ​​magnesium oxide can be measured, for example, in accordance with JIS Z 8830:2013 (ISO 9277:2010) "Method for measuring the specific surface area of ​​powders (solids) by gas adsorption".

[0040] [Magnesium oxide content] In the present invention, the magnesium oxide content is 0.1 to 1.0 parts by mass per 100 parts by mass of the above rubber component. From the viewpoint of achieving superior effects of the present invention, the magnesium oxide content is preferably 0.2 to 1.0 parts by mass per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of achieving superior effects of the present invention (particularly resistance to compression set), the magnesium oxide content is more preferably 0.2 to 0.8 parts by mass per 100 parts by mass of the rubber component.

[0041] (talc) From the viewpoint of achieving superior effects of the present invention, the rubber composition of the present invention preferably further contains talc. Talc is a mineral composed of magnesium hydroxide and silicate, Mg3Si4O 10 It is a compound represented as (OH)2.

[0042] (Talc content) If the rubber composition of the present invention further contains talc, the amount of talc is preferably 30 to 100 parts by mass, and more preferably 30 to 50 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving superior effects of the present invention.

[0043] (Ratio of talc content to carbon black content) If the rubber composition of the present invention further contains talc, the talc content is preferably 1 / 2 or less (by mass ratio) of the carbon black content, and more preferably 1 / 3 or less (by mass ratio), from the viewpoint of achieving superior effects of the present invention (particularly the compression set resistance of the resulting rubber layer).

[0044] (Total content of carbon black and talc) If the rubber composition of the present invention further contains talc, the total content of carbon black and talc is preferably 70 to 200 parts by mass, and more preferably 120 to 180 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving superior effects of the present invention.

[0045] (Additives) The rubber composition of the present invention may optionally contain further additives, provided that such additives do not impair the effects of the present invention. Examples of additives include fatty acids such as stearic acid, plasticizers such as paraffin oil, zinc oxide, and antioxidants.

[0046] (Zinc oxide) The rubber composition of the present invention preferably further contains zinc oxide (ZnO). Zinc oxide can function as a crosslinking agent for polymers (rubber) that have crosslinking points such as halogens. The zinc oxide is not particularly limited; for example, conventionally known types can be used. From the viewpoint of achieving superior effects of the present invention, the zinc oxide content is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0047] (Method for manufacturing rubber composition) The rubber composition of the present invention is not particularly limited in its manufacturing method. For example, it can be manufactured by mixing the above-mentioned essential components with optional components that can be used as needed, under conditions of, for example, 20 to 130°C.

[0048] (Crosslinking of rubber compositions) The method for crosslinking the rubber composition of the present invention is not particularly limited. The rubber composition of the present invention can be crosslinked (vulcanized) by press vulcanization, steam vulcanization, oven vulcanization (hot air vulcanization), or hot water vulcanization under conditions of 130 to 190°C (temperature conditions) and 0 to 4.0 MPa (pressure conditions). In this invention, crosslinking the rubber composition of the present invention means crosslinking and curing the rubber composition of the present invention (uncrosslinked). Specifically, the rubber components contained in the rubber composition of the present invention should be crosslinked. In this specification, crosslinking may be referred to as vulcanization for convenience.

[0049] (Application) The rubber composition of the present invention exhibits excellent adhesion between the resulting rubber layer and the resin layer, and can therefore be used adjacent to the resin layer. The rubber composition of the present invention exhibits excellent adhesion between the resulting rubber layer and the fiber-reinforced layer, and excellent strength retention between the resulting rubber layer and the adjacent fiber-reinforced layer (e.g., a synthetic resin fiber layer), and can therefore be used adjacent to a fiber-reinforced layer. The rubber composition of the present invention can be used, for example, in hoses, and more specifically, in hoses for transporting refrigerants.

[0050] [hose] The hose of the present invention is It has, in order from the innermost layer, a resin layer, a first rubber layer, a fiber reinforcement layer, and a second rubber layer. The resin layer is adjacent to the first rubber layer, and the first rubber layer is adjacent to the fiber reinforcement layer. The above resin layer is a layer comprising a polyamide and a carboxyl group-containing modified polyolefin. The first rubber layer described above is a layer formed by a cured product of the rubber composition for hoses of the present invention. The above-mentioned fiber-reinforced layer is a layer of polyethylene terephthalate fibers, and this is a hose.

[0051] The hose of the present invention may have one or more fiber-reinforced layers. If the hose of the present invention has multiple fiber-reinforced layers, it may further have intermediate rubber layers between the multiple fiber-reinforced layers.

[0052] The hose configuration of the present invention will be explained with reference to the attached diagrams. The present invention is not limited to the attached diagrams. Reference numerals shown in the diagrams will be indicated in parentheses in the following description. (Figure 1) Figure 1 is a schematic perspective view showing an example of the hose of the present invention, with each layer cut out. In Figure 1, the hose (10) has a resin layer (12), a first rubber layer (18), a fiber reinforcement layer (14), and a second rubber layer (16). The resin layer (12) is the innermost layer of the hose (10). The resin layer (12) and the first rubber layer (18) are adjacent to each other. The first rubber layer (18) and the fiber reinforcement layer (14) are adjacent to each other. The first rubber layer (18) is a rubber layer formed from the rubber composition of the present invention. In Figure 1, the outermost second rubber layer (16) is not particularly limited. For example, a conventionally known rubber layer can be used. Specifically, one preferred embodiment is that the second rubber layer (16) is a rubber layer with excellent weather resistance. In Figure 1, the hose (10) has one fiber reinforcement layer (14) as a fiber reinforcement layer. The fiber reinforcement layer (14) may be, for example, a fiber reinforcement layer formed by braided fibers.

[0053] (Figure 2) Figure 2 is a schematic perspective view showing another example of the hose of the present invention, with each layer cut out. In Figure 2, the hose (20) has a resin layer (22), a first rubber layer (28), fiber reinforcement layers (24) and (25), a second rubber layer (26), and an intermediate rubber layer (27). The resin layer (22) is the innermost layer of the hose (20). The resin layer (22) and the first rubber layer (28) are adjacent to each other. The first rubber layer (28) and the fiber reinforcement layer (24) are adjacent to each other. The first rubber layer (28) is a rubber layer formed from the rubber composition of the present invention. An intermediate rubber layer (27) is positioned between the fiber reinforcement layers (24) and (25). In Figure 2, the outermost second rubber layer (26) is not particularly limited. For example, a conventionally known rubber layer can be used. Specifically, one preferred embodiment is that the second rubber layer (26) is a rubber layer with excellent weather resistance. In Figure 2, the hose (20) has two fiber reinforcement layers, (24) and (25). Examples of fiber reinforcement layers (24) and (25) include fiber reinforcement layers formed from spirally woven fibers.

[0054] [Resin layer] The hose of the present invention has a resin layer. In the hose of the present invention, the resin layer is adjacent to a first rubber layer, which will be described later. In the hose of the present invention, the resin layer is a layer comprising polyamide and a carboxyl group-containing modified polyolefin. [polyamide] Examples of polyamides included in the resin layer include polyamide resins such as nylon 11, nylon 12, nylon 6, nylon 66, nylon 666, nylon 612, nylon 610, and nylon 46. [Carboxyl group-containing modified polyolefin] The carboxyl group-containing modified polyolefin contained in the resin layer can be any modified polyolefin having a carboxyl group (-COOH).

[0055] One preferred embodiment of the above resin layer is that it includes a resin composition containing the above polyamide and the above carboxyl group-containing modified polyolefin as the above polyamide and the above carboxyl group-containing modified polyolefin. Examples of commercially available resin compositions include the Zytel ST series, such as Zytel ST801, Zytel ST811, and Zytel ST811HS, manufactured by DuPont. (Additives) In addition to polyamide and carboxyl group-containing modified polyolefin, the resin layer may further contain, for example, additives. Examples of additives include carbon black, white fillers such as silica, vulcanizing agents or crosslinking agents, vulcanization accelerators or crosslinking accelerators, oils, and antioxidants. The content of the additives can be appropriately selected within a range that does not contradict the objectives of the present invention.

[0056] (Thickness of the resin layer) The thickness of the resin layer is not particularly limited, but it can be, for example, 0.05 to 0.30 mm. (Innermost layer) In a preferred embodiment of the present invention, the hose has a resin layer as the innermost layer of the hose.

[0057] [First rubber layer] The hose of the present invention has a first rubber layer. The hose of the present invention has, in order from the innermost layer, the resin layer, the first rubber layer, and a fibrous resin layer described later, and the first rubber layer is adjacent to the resin layer and the fibrous resin layer. In the hose of the present invention, the first rubber layer is a layer formed from a cured product of the rubber composition for hoses of the present invention. The rubber composition used in the first rubber layer is not particularly limited as long as it is the rubber composition of the present invention. (Thickness of the first rubber layer) The thickness of the first rubber layer is not particularly limited, but can be, for example, 0.2 to 3 mm.

[0058] [Fiber reinforcement layer] The hose of the present invention has a fiber-reinforced layer. In the hose of the present invention, the first rubber layer is adjacent to the fiber-reinforced layer. In the hose of the present invention, the fiber-reinforced layer is a layer formed of polyethylene terephthalate fibers. The fiber-reinforced layer can be any layer formed from polyethylene terephthalate (PET) fibers (reinforcement threads). Examples of polyethylene terephthalate (PET) fibers that form the fiber reinforcement layer include untreated PET fibers and PET fibers treated with RFL (resorcinol-formaldehyde-latex adhesive). Examples of fiber reinforcement layers include those braided into a spiral or blade structure. The hose of the present invention may have one or more fiber-reinforced layers. (Thickness of the fiber reinforcement layer) The thickness of the fiber reinforcement layer (or the thickness of each fiber reinforcement layer if the fiber reinforcement layer consists of multiple layers) is not particularly limited, but can be, for example, 0.3 to 3 mm.

[0059] If the hose of the present invention has multiple fiber-reinforced layers, it is sufficient that one of the multiple fiber-reinforced layers is arranged adjacent to the first rubber layer. If the hose of the present invention has multiple fiber-reinforced layers, the multiple fiber-reinforced layers only need to be arranged between the first rubber layer and the second rubber layer described later.

[0060] (Intermediate rubber layer) If the hose of the present invention has multiple fiber-reinforced layers, it may further have an intermediate rubber layer between the multiple fiber-reinforced layers. If the hose of the present invention further has an intermediate rubber layer, the material of the intermediate rubber layer is not particularly limited as long as it is a rubber composition that has excellent adhesion to the fiber-reinforced layers. The thickness of the intermediate rubber layer can be, for example, 0.1 to 3 mm.

[0061] [Second rubber layer] The hose of the present invention has a second rubber layer. The material of the second rubber layer is not particularly limited. For example, it could be the same as the rubber material used in the outermost layer of a conventional hose. Specifically, one preferred embodiment is that the rubber layer has excellent weather resistance. (Thickness of the second rubber layer) The thickness of the second rubber layer is not particularly limited, but can be, for example, 0.2 to 3 mm. (outermost layer) In the hose of the present invention, the second rubber layer can be the outermost layer of the hose of the present invention.

[0062] The hose of the present invention has, in order from the innermost layer, a resin layer, a first rubber layer, a fiber reinforcement layer, and a second rubber layer. Furthermore, in the hose of the present invention, the resin layer is adjacent to the first rubber layer, and the first rubber layer is adjacent to the fiber reinforcement layer. In other words, in the hose of the present invention, the resin layer, the first rubber layer, and the fiber resin layer are laminated in order from the innermost layer, and the first rubber layer is adjacent to the resin layer and the fiber resin layer.

[0063] In the hose of the present invention, one preferred embodiment is that the resin layer, the first rubber layer, the fiber reinforcement layer, and the second rubber layer are laminated in this order and adjacent to each other. Furthermore, in the case where the hose of the present invention has a plurality of fiber-reinforced layers and an intermediate rubber layer between the plurality of fiber-reinforced layers, one preferred embodiment is that the resin layer, the first rubber layer, N sets of the fiber-reinforced layer and the intermediate rubber layer, the fiber-reinforced layer, and the second rubber layer are laminated in this order and adjacent to each other. The N sets can be 1 to 10.

[0064] (Hose manufacturing method) The manufacturing method of the hose of the present invention is not particularly limited. For example, a resin composition for forming a resin layer, a rubber composition of the present invention for forming a first rubber layer, PET fibers for forming a first fiber reinforcement layer, a rubber composition for an intermediate rubber layer, PET fibers for forming a second fiber reinforcement layer, and a rubber composition for forming a second rubber layer can be laminated on a mandrel in the manner of the desired hose. The laminate can then be crosslinked (vulcanized) by press vulcanization, steam vulcanization, oven vulcanization (hot air vulcanization), or hot water vulcanization at 130 to 190°C for 30 to 180 minutes to integrate the laminate, thereby manufacturing the hose of the present invention. In the above, the hose of the present invention may be manufactured by coating the laminate before crosslinking with a protective film, for example, polymethylpentene, crosslinking as described above, and then peeling the protective film off the crosslinked laminate.

[0065] The hose of the present invention can be used, for example, as a hose for transporting refrigerants. Specific applications of the hose of the present invention include, for example, hoses for car air conditioning systems and hoses for indoor air conditioning systems. [Examples]

[0066] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

[0067] <Manufacturing of rubber compositions> Each rubber composition was produced by mixing the components shown in the tables below in the proportions (parts by mass) indicated in the tables using a stirrer.

[0068] <Rating> The following evaluations were performed using each rubber composition manufactured as described above. The results are shown in the respective tables.

[0069] <Compression set resistance of the rubber layer> Each of the obtained rubber compositions was press-vulcanized for 45 minutes at 153°C and a surface pressure of 3.5 MPa using a press molding machine with a mold having a diameter of 29.05 mm and a thickness of 12.5 mm, to produce disc-shaped test specimens (with a diameter of 29.0 ± 0.5 mm and a thickness of 12.5 ± 0.5 mm). Using the above test specimens, a compression set test was performed in accordance with JIS K6262:2013 under the conditions of a test temperature of 70°C, a test duration of 22 hours, and a compressibility of 25%, and the compression set (%) was measured.

[0070] • Evaluation criteria for compression set In this invention, when the compression set is 60% or less, the resulting rubber layer is evaluated as having excellent compression set resistance. Excellent compression set resistance of the rubber layer means that the hose has excellent sealing properties. The less the compression set is below 60%, the better the compression set resistance of the rubber layer.

[0071] <Maintenance of strength between the rubber layer and the adjacent fiber-reinforced layer> • Sample preparation An unvulcanized sheet with a thickness of 2.5 mm, prepared from each of the rubber compositions obtained as described above, was wound onto an iron mandrel with an outer diameter of 35 mm. Next, twisted polyethylene terephthalate fibers (RFL treated) were wound spirally around the sheet to form a fiber reinforcement layer. Then, another unvulcanized sheet, identical to the above unvulcanized sheet, was laminated onto the fiber reinforcement layer to prepare an unvulcanized hose-shaped test specimen. Next, a curing tape (protective cloth) made of nylon 66 was wrapped around the outside of the unvulcanized hose-shaped test specimen prepared as described above, and oven vulcanization was performed at 160°C for 100 minutes. After vulcanization, the curing tape was removed to obtain a vulcanized hose-shaped test specimen. The vulcanized hose-shaped test specimen has a three-layer structure from the inside out: a rubber layer, a fiber reinforcement layer, and another rubber layer.

[0072] • Heating test As described above, the vulcanized hose-shaped test specimens were placed at 135°C for 96 hours, and after 96 hours, heating was stopped and they were allowed to cool. In the longitudinal central portion of the vulcanized hose-shaped test piece after cooling, the rubber layer on the surface was cut out and peeled off along the circumference of the hose to expose the fiber reinforcement layer. • Measurement of the strength of the fiber reinforcement layer As described above, fibers were extracted from a hose-shaped test specimen after vulcanization, in which the fiber reinforcement layer was exposed. Using an Autograph ASG-X (Shimadzu Corporation), the fibers extracted from the sample were pulled under a tensile speed of 300 mm / min, and the strength of the fibers in the vulcanized hose-shaped test specimen was measured. On the other hand, to determine the strength of the fibers before vulcanization, the twisted polyethylene terephthalate fibers were pulled under conditions of a tensile speed of 300 mm / min using an Autograph ASG-X (Shimadzu Corporation), and the strength of the fibers before vulcanization was measured. The strength obtained as described above was applied to the following formula to determine the strength retention rate of the fiber. Fiber strength retention rate (%) = B / A × 100 A: Strength of the fiber before vulcanization B: Fiber strength of the hose-shaped test specimen after vulcanization • Criteria for evaluating the retention rate of fiber strength In this invention, when the retention rate obtained as described above is 55% or higher, the strength retention of the rubber layer and the adjacent fiber reinforcement layer is evaluated as excellent. The greater the retention rate above 55%, the better the strength retention.

[0073] <Adhesion between the rubber layer and the fiber reinforcement layer> • Sample preparation <Retention of Strength Between the Rubber Layer and the Adjacent Fiber Reinforcement Layer> A vulcanized hose-shaped test specimen was prepared according to the method described above for sample preparation. The hose-shaped test specimen obtained as described above was cut to obtain a cylindrical sample with a length of 35 mm. As described above, the 35 mm long cylindrical sample obtained is a cylindrical laminate in which, from the inside out, a first rubber layer made of the hardened rubber composition, a fiber-reinforced layer of polyethylene terephthalate fibers, and a second rubber layer made of the same hardened rubber composition are laminated together. The second rubber layer is the outermost layer of the 35 mm long cylindrical sample. Furthermore, the second rubber layer covers the outer circumference of the 35 mm long cylindrical sample. Next, for the cylindrical sample described above, a second rubber layer 5 mm wide was removed from each end of the 35 mm long cylindrical sample. After removing the 5 mm wide second rubber layer as described above, a second rubber layer 25 mm wide remained in the center of the surface of the 35 mm long cylindrical sample. As described above, a cylindrical sample Z having a second rubber layer with a width of 25 mm in the center of the surface was obtained. • Measurement of peeling force For the sample Z obtained as described above, the end of the 25 mm wide second rubber layer located in the center of the surface of the sample Z was grasped using a Strograph E3-L (Toyo Seiki Seisakusho Co., Ltd.). The end of the second rubber layer, which was formed after the unvulcanized sheet was wrapped around the hose-shaped test piece and vulcanized, was cut along its longitudinal direction, and the end of the second rubber layer was peeled from the fiber-reinforced layer to a length that could be grasped by the Strograph. The grasped 25 mm wide second rubber layer was then pulled in a direction perpendicular to the axial direction of the cylindrical sample Z under a peeling speed of 50 mm / min, and the force required to peel the 25 mm wide second rubber layer from the sample Z (peeling force) was measured. The average peeling force (in N / mm) was calculated by dividing the obtained peeling force by 25, and this is shown in the "Peeling Force (Average)" column of each table. • Evaluation criteria for peeling force In this invention, when the peel force obtained as described above is 1.2 N / mm or greater, the adhesion between the rubber layer and the fiber reinforcement layer is evaluated as excellent. The greater the peel force is than 1.2 N / mm, the better the adhesion between the rubber layer and the fiber reinforcement layer.

[0074] <Adhesion between resin layer and rubber layer> • Sample preparation As described above, each rubber composition was prepared into two unvulcanized rubber sheets with a thickness of 2 mm. Next, a 0.2 mm thick sheet of Zytel ST811HS (manufactured by DuPont; a resin composition containing polyamide 6 and carboxyl group-containing modified polyolefin) was sandwiched between two of the above unvulcanized rubber sheets to form a three-layer laminate. This laminate was then press-vulcanized at 153°C and a press pressure of 2 MPa for 45 minutes to produce strip-shaped samples with a width of 25 mm and a length of 150 mm. • Measurement of peeling force Using a Strograph E3-L (Toyo Seiki Seisakusho Co., Ltd.), the vulcanized rubber layer (1 layer) and the remaining two layers were each grasped at one end (25 mm wide) of the sample obtained as described above, and pulled up and down under a peeling speed of 50 mm / min to measure the peeling force. The obtained peeling force was divided by 25 to calculate the average peeling force (in N / mm), which is shown in the "Peeling Force (Average)" column of each table. • Evaluation criteria for peeling force In this invention, when the peeling force obtained as described above exceeds 1.2 N / mm, the adhesion between the resin layer and the rubber layer is evaluated as excellent. The greater the peeling force is than 1.2 N / mm, the better the adhesion between the resin layer and the rubber layer.

[0075] [Table 1]

[0076] [Table 2]

[0077] [Table 3]

[0078] [Table 4]

[0079] The details of each component shown in the tables above are as follows: (Rubber X) (Bromide of copolymer rubber of isomonoolefin and p-alkylstyrene) • BIMS: Exxpro 3745, manufactured by Exxonmobil Chemical Company. A brominated copolymer rubber in which p-methylstyrene is a C4 isomonoolefin (isobutylene) and p-methylstyrene, and p-methylstyrene is brominated to bromomethylstyrene. The content of repeating units due to the above bromomethylstyrene was 1.2 mol% of the total amount of repeating units constituting the above BIMS.

[0080] (Halogenated butyl rubber) • Br-IIR: Brominated butyl rubber (bromobutyl rubber represented by the following formula). Trade name: X_Butyl BB X2, manufactured by Alantheo. Bromine content: 1.8% by mass. [ka]

[0081] (Rubber Y) • EPDM: Mitsui EPT4070, manufactured by Mitsui Chemicals, Inc. Diene component: ENB, Diene content: 8.1% by mass, Mooney viscosity at 125°C: 47 • Cl-IIR: Chlorinated butyl rubber. Product name: EXXON Chlorobutyl 1066, manufactured by Nippon Butyl Co., Ltd. Chlorine content: 1.25% by mass • IIR: Butyl rubber. EXXON BUTYL 268, manufactured by Nippon Butyl Co., Ltd.

[0082] (Carbon Black) · HAF Carbon Black: HAF carbon black. Trade name: DASH BLACK N330, manufactured by OCI Company Ltd. DBP absorption 102 ± 5 cm 3 / 100 g, iodine adsorption 81 ± 5 mg / g. · SRF Carbon Black: SRF carbon black. Trade name: Asahi #50, manufactured by Asahi Carbon Co., Ltd. DBP absorption 62 ± 12 cm 3 / 100 g, iodine adsorption 23 ± 5 mg / g.

[0083] · Talc: Trade name ImerFlex T20 (manufactured by Imerys Specialties Japan)

[0084] (Magnesium Oxide) · MgO 150: Magnesium Oxide (trade name KyowaMag 150, BET specific surface area 144 m 2 / g, manufactured by Kyowa Chemical Industry Co., Ltd.) · MgO 30: Magnesium Oxide (trade name KyowaMag 30, BET specific surface area 42 m 2 / g, manufactured by Kyowa Chemical Industry Co., Ltd.)

[0085] · St Acid: Stearic Acid. Trade name Stearic Acid 50S, manufactured by Nisshin Rika Co., Ltd · Paraffin Oil: Y Pure Spin G, manufactured by Cosmo Oil Lubricants Co., Ltd · Zinc Oxide: Zinc Oxide. Three types of zinc oxide, manufactured by Shoindo Chemical Industry Co., Ltd

[0086] (Phenolic Resin) · Phenolic Resin: Product name PR 2500, manufactured by RESONAC. The above PR 2500 is a mixture containing 96% by mass or more of alkylphenol formaldehyde resin, 3.0% by mass of p - octylphenol, toluene, etc. · Br - Phenolic Resin: Brominated alkylphenol formaldehyde resin. Tackiol 250 - I, manufactured by Taoka Chemical Industry Co., Ltd

[0087] As shown in Tables 1-3, Comparative Examples 1, 6, and 9, which do not contain magnesium oxide, Comparative Examples 2, 3, 7, 8, 10, and 11, in which the magnesium oxide content falls outside the specified range, and Comparative Examples 4 and 5, in which the phenolic resin content falls outside the specified range, all exhibited insufficient compression set resistance of the resulting rubber layer, adhesion between the resin layer and the rubber layer, adhesion between the rubber layer and the fiber reinforcement layer, and strength retention between the rubber layer and the adjacent fiber reinforcement layer.

[0088] In contrast, the rubber composition of the present invention exhibits excellent resistance to compression set in the resulting rubber layer, adhesion between the resin layer and the rubber layer, adhesion between the rubber layer and the fiber reinforcement layer, and strength retention between the rubber layer and the adjacent fiber reinforcement layer. The hose of the present invention exhibits excellent resistance to compression set in the rubber layer, adhesion between the resin layer and the rubber layer, adhesion between the rubber layer and the fiber reinforcement layer, and strength retention between the rubber layer and the adjacent fiber reinforcement layer. [Explanation of Symbols]

[0089] 10, 20 hoses 12, 22 Resin layer 14, 24, 25 Fiber reinforced layer 16, 26 Second rubber layer 18, 28 First rubber layer 27 Intermediate rubber layer

Claims

1. A rubber component comprising 30 to 100 parts by mass of one or more types of rubber X selected from the group consisting of brominated copolymer rubbers of isomonoolefins and p-alkylstyrenes, and halogenated butyl rubber (excluding chlorinated butyl rubber), and having a content of 0 to 70 parts by mass of one or more types of rubber Y selected from the group consisting of butyl rubber, chlorinated butyl rubber, and EPDM, per 100 parts by mass of the rubber component: Carbon black 20 parts by mass or more, 1.0 to 15 parts by mass of phenolic resin, A rubber composition for hoses containing 0.1 to 1.0 parts by mass of magnesium oxide.

2. The rubber composition for hoses according to claim 1, wherein the halogenated butyl rubber is brominated butyl rubber.

3. The rubber composition for hoses according to claim 1, wherein the magnesium oxide content is 0.2 to 1.0 parts by mass per 100 parts by mass of the rubber component.

4. The rubber composition for hoses according to claim 1, wherein the phenolic resin comprises an alkylphenol formaldehyde resin and / or a brominated alkylphenol formaldehyde resin, and the content of the phenolic resin is 1.0 to 10 parts by mass per 100 parts by mass of the rubber component.

5. The rubber composition for hoses according to claim 1, further containing talc, wherein the amount of talc is 30 to 100 parts by mass per 100 parts by mass of the rubber component.

6. The rubber composition for hoses according to claim 5, wherein the talc content is 1 / 2 or less of the carbon black content.

7. It has, in order from the innermost layer, a resin layer, a first rubber layer, a fiber reinforcement layer, and a second rubber layer. The resin layer is adjacent to the first rubber layer, and the first rubber layer is adjacent to the fiber reinforcement layer. The aforementioned resin layer is a layer comprising a polyamide and a carboxyl group-containing modified polyolefin. The first rubber layer is a layer formed from a cured product of the rubber composition for hoses described in any one of claims 1 to 6. A hose in which the fiber-reinforced layer is a layer of polyethylene terephthalate fibers.

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