JP2005351364A - Rubber hose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber hose of which a gas barrier layer is made from polyamide of metaxylene diamine, exhibiting high gas barrier performance and sufficient flexibility. <P>SOLUTION: A rubber hose 1 comprises a rubber layer and a gas barrier layer. The gas barrier layer 2 is made from polyamide of mataxylene diamine. The rubber hose 1 can comprise a composite layer consisting of a rubber layer such as an inside rubber layer (innermost layer rubber) 3 inside the gas barrier layer 2, an outside rubber layer (inner tube rubber) 4 outside the gas barrier layer 2, an intermediate rubber layer (intermediate rubber )5, and an armoring rubber layer (armoring rubber) 6 and reinforcing layers (reinforcing thread) 7 and 8 as well as the gas barrier layer 2. The rubber hose 1 is excellent in gas barrier property, and sufficiently satisfies sealing requirement at a caulking part as well as vibration resistance and heat resistance requirements. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber hose composed of a composite layer including a rubber layer and a gas barrier layer, and more particularly to an automobile cooler hose and a high pressure line rubber hose.

  As a refrigerant transport line for automobiles, a rubber hose is generally used because the refrigerant does not leak and at the same time vibration absorption performance is required.

  Refrigerant transport hoses used for automobile applications are roughly classified into high-pressure lines and low-pressure lines. The high-pressure line is a line that supplies high-temperature refrigerant that has been compressed by a compressor into a gas-liquid mixed state to the condenser at high pressure. The low-pressure line is a line for returning the low-pressure / low-temperature refrigerant evaporated by the evaporator to the compressor.

  The amount of refrigerant leakage is remarkable in the high-pressure line due to the mechanism, and countermeasures are required. For this reason, various hose structures used for automobile cooler hoses (high-pressure lines) are known (for example, see Patent Document 1) and are mass-produced.

  FIG. 2 is a perspective view showing an internal structure of one conventional cooler hose. The cooler hose 21 includes, from the inside, a gas leakage prevention layer 22 made of nylon, an inner tube rubber 23, a reinforcing thread 24, an intermediate rubber 25, a reinforcing thread 26, and a jacket rubber 27. The gas leakage prevention layer 22 is an innermost layer in order to prevent refrigerant leakage, and is made of a nylon resin that has excellent gas barrier properties and dynamic durability such as impulse resistance.

On the other hand, the progress of resin materials has been remarkable. Recently, conventional resin materials such as polyamide (Mitsubishi Gas Chemical Co., Ltd. “MX Nylon”) made of ethylene / vinyl alcohol copolymer (EVOH) and metaxylenediamine are used. A resin material having a gas barrier performance which is not present in the industry has begun to spread industrially (for example, see Non-Patent Document 1).
JP 2004-35708 A Mitsubishi Gas Chemical Co., Ltd., “MX Nylon” Web Catalog ”, [online], [Search June 3, 2004], Internet <URL http://www.mgc.co.jp/aromatic/nmxd6/catalog /index.html>

  Nowadays, environmental problems have been greatly taken up, and the global warming potential of Freon gas R-134a, which is used as a refrigerant in automobile coolers, is becoming a problem. In response to this trend, a new fluoridation gas emission control plan was adopted by the EU in mid-2003, and automobiles and other companies have significantly increased the amount of refrigerant leakage from cooler hoses as original equipment (OE). Reductions are a major concern. For this reason, in the gas barrier layer which has polyamide currently used as a main component, gas barrier performance is not enough and a fundamental review is required.

  Polyamides composed of the meta-xylenediamine described above (“MX nylon”, etc., hereinafter may be simply referred to as “MX-PA”) have excellent gas barrier performance, and particularly good for chlorofluorocarbon gas. It is a very attractive material for providing a hose that exhibits gas barrier performance and meets environmental regulations.

  However, usually, a resin material having high gas barrier performance has a drawback that the hardness is remarkably increased, and it is difficult to apply the resin material to applications requiring flexibility.

  An object of the present invention is to obtain a rubber hose whose gas barrier layer is made of polyamide of metaxylenediamine. Moreover, the subject of this invention is providing the rubber hose which exhibits sufficient softness | flexibility with high gas barrier performance.

  The present invention relates to a rubber hose comprising a rubber layer and a gas barrier layer, wherein the gas barrier layer is made of metaxylenediamine polyamide.

  According to the present invention, by forming the gas barrier layer of the rubber hose from polyamide of metaxylenediamine, the rubber hose can exhibit extremely high gas barrier performance. In addition, such a gas barrier layer can exhibit sufficient flexibility in the rubber hose, although it has relatively high rigidity.

An embodiment for carrying out the present invention will be described.
(1) Rubber hose A rubber hose and a gas barrier layer are provided. The rubber hose is not particularly limited, and can be a composite layer including a reinforcing layer, an intermediate rubber layer, a jacket rubber layer, and the like. The rubber hose can be used for various applications. Desired gas barrier properties (or referred to as air permeation resistance) can be exhibited. The rubber hose can have desired flexibility, dynamic durability, and the like. It can be used as a refrigerant transport hose, in particular, an automobile cooler hose, or these or other various high-pressure line hoses.

(2) Gas barrier layer As mentioned earlier, MX-PA is a very rigid material and cannot be put into practical use simply by replacing the polyamide layer of a conventional automotive cooler hose with the MX-PA layer. It was considered. Therefore, the present inventors have developed a flexible formulation of MX-PA by a laminated structure with a flexible and durable polyamide (hereinafter sometimes simply referred to as “PA”) or alloying with polyolefin. Yes.

  However, in the laminated structure of MX-PA with PA, there is a problem of capital investment and technical difficulty in production in forming the laminated body, and even in the softening recipe, the MX-PA phase and the olefin In order to obtain a finely dispersed structure with the phase, high manufacturing technology is required.

  As described above, the refrigerant transport hoses currently on the market use a resin layer for the purpose of ensuring gas barrier properties as the innermost layer. It was thought that applying MX-PA with a structure in which a resin is arranged in the innermost layer is not practical because MX-PA is inferior in flexibility.

  Since the present inventor has excellent CFC gas barrier performance, MX-PA can be applied with a thin film thickness, and therefore, by arranging rubber in the innermost layer or directly adhering to rubber, etc. It has been found that a rubber hose having excellent gas barrier performance can be obtained with a gas barrier layer made of MX-PA alone, and sufficient flexibility as a rubber hose can be secured.

  The gas barrier layer is made of metaxylenediamine polyamide (MX-PA). MX-PA is not particularly limited, and various polyamides can be used. For example, MX-PA is a crystalline polyamide obtained from a polycondensation reaction between metaxylenediamine (MXDA) and adipic acid.

  The film thickness can be set thinner than that of conventional nylon due to the high gas barrier property of MX-PA. For example, the film thickness is 20 to 150 μm, preferably 35 to 80 μm. In the gas barrier layer having a thickness within such a range, a sufficient gas barrier property (air permeability resistance) can be obtained, and further, the rubber hose can be provided with sufficient flexibility, dynamic durability, and the like.

(3) Inner rubber layer The rubber hose can have an inner rubber layer inside the gas barrier layer. The inner rubber layer can be provided so as to contact the inner side of the gas barrier layer. The inner rubber layer can form the innermost layer of the rubber hose. If the innermost layer is a resin, in order to secure sufficient sealing performance when crimping with a nipple, it depends largely on the application of the adhesive, but by using the innermost layer as rubber, the amount of adhesive required It can suppress, and it can be made to make a sealing performance secure and cost reduction.

  When the inner rubber layer is the innermost layer of the rubber hose, the inner rubber layer is in contact with the fluid such as a refrigerant, and is excellent in water resistance and liquid resistance (oil, chemicals, etc.), and causes problems due to leakage, permeation, etc. It is preferable that it is made of a rubber material that is not allowed to be removed.

  The inner rubber layer can be adhered to the gas barrier layer by various means. Preferably, the inner rubber layer and the gas barrier layer are bonded by a direct bonding technique without applying an adhesive or the like. The present inventor has developed a direct adhesion technique between a rubber member and a resin member in a previous study.

  By using such a technique, the inner rubber layer can be directly bonded to the gas barrier layer. Such adhesion forms a bond by interaction between the inner rubber layer and the gas barrier layer. The bond by interaction can be composed of at least one kind of physical bond such as entanglement of molecular chains, chemical bond such as cross-linking, hydrogen bond and coordination bond.

  In direct bonding, the inner rubber layer can be made of a rubber composition containing resorcin and a compound that becomes a methylene donor. The compound serving as a methylene donor may be at least one of an amine compound and a formaldehyde compound. Preferably, the amine compound is hexamethylenetetramine, hexamethylenediamine or the like, particularly preferably hexamethylenetetramine. The formaldehyde compound can be selected from the group consisting of formalin, paraformaldehyde, trioxane and the like.

  The rubber composition is not particularly limited as a rubber component, and various general-purpose polymers can be blended. For example, as the rubber component, nitrile butadiene rubber (hereinafter referred to as “NBR”), hydrogenated nitrile butadiene rubber (hereinafter referred to as “HNBR”), chlorinated butyl rubber (hereinafter referred to as “Cl-IIR”). And at least one polymer selected from the group consisting of halogenated butyl rubber such as brominated butyl rubber (hereinafter referred to as “Br-IIR”), regular butyl rubber (hereinafter simply referred to as “IIR”), and the like. Can be used. Preferably, the rubber composition is mainly composed of a highly polar polymer such as NBR.

  The rubber composition can contain silica, a silane coupling agent, and the like. Thereby, in addition to the coupling | bonding by interaction between the rubber | gum and a gas barrier layer, stable adhesion | attachment can be obtained by the hydrogen bond by silica etc., or a dehydration condensation reaction. The rubber composition is a known vulcanization agent such as an amine-based anti-aging agent, carbon black, oil, microwax, a filler such as zinc oxide, a vulcanizing agent, a vulcanization accelerator, and a vulcanization acceleration aid. Systems such as vulcanization systems such as sulfur, peroxide and zinc white can be used.

  Direct adhesion between the inner rubber layer and the gas barrier layer can be performed by bringing the rubber composition and MX-PA into contact with each other and heating. When such a rubber composition is brought into contact with MX-PA at the time of heating such as vulcanization or molding, the resorcin (R) and the compound (D) serving as a methylene donor in the rubber composition form an RD polymer, and RD The polymer forms a bond by interaction with the functional group of MX-PA. The bond by the RD polymer can also be formed by contact between the rubber composition and molten MX-PA. Preferably, the bond by interaction is formed by simultaneously proceeding the vulcanization reaction of the rubber composition and the formation reaction of the RD polymer.

(4) Outer rubber layer The rubber hose can be provided with an outer rubber layer outside the gas barrier layer. The outer rubber layer can be provided in contact with the outer side of the gas barrier layer. Similar to the inner rubber layer described above, it can be made of a rubber composition containing a compound that forms resorcin and a methylene donor, silica, and the like, and can form a bond by interaction with the gas barrier layer. The outer rubber layer can also be formed by adhering the aforementioned rubber composition to molten MX-PA.

(5) Reinforcing layer The rubber hose can be provided with a reinforcing layer. The reinforcing layer can be provided outside the outer rubber layer. The reinforcing layer can be made of reinforcing fibers. As the reinforcing fiber, a fiber made of cotton, vinylon, nylon, polyester, polyethylene terephthalate (PET) or the like, or a steel such as a hard steel wire is used depending on the purpose of pressure resistance. The reinforcing fiber can form a reinforcing layer by braiding, spiraling, cloth winding or the like. When a plurality of reinforcing layers are provided, an intermediate rubber layer can be provided between them in order to prevent fiber damage due to abrasion. The intermediate rubber layer can be made of various rubbers, for example, an IIR rubber composition.

(6) Outer Rubber Layer The rubber hose can be provided with an outer rubber layer in the outermost layer. The jacket rubber layer can have weather resistance. Since the outer rubber layer is exposed to the outside air, a rubber material resistant to chemicals such as oil, acid and alkali can be used according to ozone resistance, oxidation resistance deterioration, and use. The outer rubber layer can be made of a rubber material that can withstand abrasion, vibration, and bending, and colored rubber can be used in some cases. The outer rubber layer can be made of an EPDM (ethylene / propylene / diene terpolymer) rubber composition having excellent weather resistance.

  The outer rubber layer can be composed of RD blending (blending of resorcin and a compound serving as a methylene donor) of rubber such as NBR rubber, HNBR rubber, and HNBR / NBR mixed rubber. Such a jacket rubber layer can improve the weather resistance of the rubber hose by bonding the rubber layer such as the outer rubber layer to rubber-rubber. The structure of the rubber hose is an inner rubber layer (RD blend) -gas barrier layer-outer rubber layer-weather-resistant outer rubber layer (RD blend).

  In the case of the gas barrier structure hose, the weather resistance can also be improved by applying an adhesive on the gas barrier layer and coating the weather resistant outer rubber layer thereon. The structure of such a rubber hose is an inner rubber layer (RD blend) -gas barrier layer-adhesive-weather-resistant outer rubber layer (RD blend).

The present invention will be described in more detail with reference to the drawings.
FIG. 1 is a perspective view showing an internal structure of a rubber hose as an example of the present invention.
The rubber hose 1 includes a gas barrier layer 2, and the gas barrier layer 2 is made of polyamide of metaxylenediamine. The rubber hose 1 includes a gas barrier layer 2, an inner rubber layer (innermost layer rubber) 3 inside the gas barrier layer 2, an outer rubber layer (inner tube rubber) 4 outside the gas barrier layer 2, and an intermediate rubber layer (intermediate rubber) 5. And a rubber layer such as an outer rubber layer (outer rubber) 6 and a composite layer including a reinforcing layer (reinforcing yarn) 7 and 8. The rubber hose 1 is excellent in gas barrier properties and can sufficiently satisfy the caulking portion sealing performance, vibration durability, heat resistance, and the like.

The present invention will be described based on examples.
(Example 1)
An automobile cooler hose as shown in FIG. 1 was produced. This hose includes an inner rubber layer, a gas barrier layer, an outer rubber layer, a reinforcing layer, an intermediate rubber layer, a reinforcing layer, and an outer rubber layer from the inside.

  As the inner rubber layer, a rubber material (RH blend) containing resorcin (R) and hexamethylenetetramine (H) as a main component is a highly polar polymer such as NBR. On the inner rubber layer, a polyamide (MX-PA) layer (thickness 50 μm) made of metaxylenediamine is disposed as a gas barrier layer. Further, on the gas barrier layer, the same rubber material (RH blending) as that of the inner rubber layer is again disposed as the outer rubber layer. Two reinforcing layers made of organic fibers such as PET are disposed on the outer rubber layer, and an intermediate rubber layer made of a normal rubber material such as IIR is disposed therebetween. An ordinary rubber material having excellent weather resistance such as EPDM is disposed on the reinforcing layer. These are vulcanized, and finishing such as cutting and printing is performed as necessary.

(Example 2)
In Example 1, an automobile cooler hose is manufactured in the same manner as in Example 1 except that the thickness of the MX-PA layer is 150 μm.

(Comparative Example 1)
In Example 1, the inner rubber layer is not used, the innermost layer is a gas barrier layer (thickness 250 μm) made of a normal polyamide 6 (PA6) resin, and the outer rubber layer is made of a normal rubber material such as IIR. A rubber hose is produced in the same manner as in Example 1 except that it is formed.
(Comparative Example 2)
In Comparative Example 1, a rubber hose is produced in the same manner as in Comparative Example 1 except that the gas barrier layer has a laminated structure of a PA6 resin (thickness 250 μm) or the like and an MX-PA layer (thickness 50 μm).

The hoses obtained in the examples and comparative examples are tested for gas barrier properties, flexibility and dynamic durability. The results are shown in Table 1.
The gas barrier property is measured as the amount of refrigerant decrease when the refrigerant HFC-134a is sealed at 0.6 g / cm ³ in a hose and left at 90 ° C. for 96 hours. The index of the amount of transmission with respect to Comparative Example 1 exceeds 0.6 and is 1.0 or less.
Flexibility is determined by measuring the bending load when wound around a mandrel having a radius of 100 mm by a half circle, ◎ 10N or less, ◎ 10N to 15N or less ◯, 15N or more 20N or less Δ, and 20N or more ×.
For dynamic durability, PAG (polyalkylene glycol) oil is sealed inside the hose, and after pre-aging at 130 ° C for 30 days, the hose is attached upside down with a mounting span of 270 mm. Repeated pressure test is performed on the medium.
・ Implemented 150,000 times at an ambient temperature of 130 ° C., pressure 0 ← → 3.5 MPa, pressure cycle 15 cpm, no oil leakage, no appearance abnormality, no airtight abnormality in 3.5 MPa airtight test with nitrogen gas The case is ◎.
・ Ambient temperature 110 ° C, pressure 0 ← → 3.5 MPa, pressure cycle 15 cpm, 150,000 cycles, no oil leakage, no appearance abnormality, no airtight abnormality in 3.5 MPa airtight test with nitrogen gas The case is ◯.
・ After 150,000 cycles at an ambient temperature of 110 ° C., a pressure of 0 ← → 3.5 MPa, and a pressure cycle of 15 cpm, an oil leak, an abnormal appearance, or a leak test of 3.5 MPa with nitrogen gas is detected. The case where it did is made x.

  As shown in Table 1, the rubber hoses of Examples 1 and 2 are provided with an unprecedented gas barrier layer composed of an MX-PA layer, and exhibit sufficient gas barrier properties. In particular, in Example 1, flexibility and dynamic durability are also satisfactory. Comparative Example 1 uses a conventional PA6 resin layer as a gas barrier layer, and is inferior in gas barrier properties. Comparative Example 2 was developed in another application by the present inventors and uses a laminated structure of a PA6 resin layer and an MX-PA layer for the gas barrier layer. Although the rubber hose of Comparative Example 2 shows good gas barrier properties, flexibility and dynamic durability, it requires a laminated structure for the gas barrier layer, and there are other problems of capital investment and technical difficulties in production. Yes.

  In the present invention, by using a rubber layer (RD blend) or the like that directly adheres to MX-PA, MX-PA having excellent gas barrier performance but relatively high rigidity can be applied as it is in a rubber hose that requires flexibility. Since it is possible to achieve both high gas barrier performance and flexibility, it is possible to provide a rubber hose that is advantageous in terms of cost performance. According to the present invention, a new structure and a high-performance rubber product can be expected.

It is a perspective view which shows the internal structure of the rubber hose of one example of this invention. It is a perspective view which shows the internal structure of the cooler hose for motor vehicles of 1 prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber hose 2 Gas barrier layer 3 Inner rubber layer 4 Outer rubber layer 5 Intermediate rubber layer 6 Outer rubber layer 7, 8 Reinforcement layer

Claims (6)

  A rubber hose comprising a rubber layer and a gas barrier layer, wherein the gas barrier layer is made of metaxylenediamine polyamide.   The rubber hose according to claim 1, wherein the rubber hose includes an inner rubber layer in contact with the gas barrier layer.   The rubber hose according to any one of claims 1 to 3, wherein the rubber hose includes an outer rubber layer in contact with the gas barrier layer.   The rubber hose according to claim 2 or 3, wherein the gas barrier layer forms a bond by interaction with the inner rubber layer or the outer rubber layer.   The rubber hose according to any one of claims 2 to 4, wherein the inner rubber layer or the outer rubber layer is made of a rubber composition containing resorcin and a compound serving as a methylene donor.   The rubber hose according to claim 5, wherein the rubber composition contains a highly polar polymer as a main component, and the methylene donor is hexamethylenetetramine.

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