JPH0469479A - Refrigerant transporting hose - Google Patents

Abstract

PURPOSE:To prevent generation of a crack in an adhesive layer so as to improve durability by setting a modulus of shearing elasticity of the adhesive layer, which is used for bonding a gas barrier layer to an inner tube rubber layer, at a room temperature lower than a predetermined value. CONSTITUTION:There is provided an inner tube layer where a gas barrier layer is bonded to a rubber layer with an adhesive layer, thus obtaining a refrigerant transporting hose. If a sample of an impulse test is observed through an electron microscope when a modulus of shearing elasticity of the adhesive layer at a room temperature exceeds 1 X 10<9> dyne/cm<2>, it is found that a crack is first generated in the adhesive layer to grow to breakage. When the modulus of shearing elasticity is lower than the above-mentioned value, an observation result shows that any crack cannot be generated and sufficient durable improvement efficiency can be obtained. Therefore, if the modulus of shearing elasticity is set lower than 1 X 10<9> dyne/cm<2>, permeation of freon gas or water can made small and the transporting hose excellent in durability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a refrigerant transport hose, and more particularly to a refrigerant transport hose suitably used as piping for automobile air conditioners and the like.

[Prior art] In recent years, the ozone layer in the stratosphere, which absorbs ultraviolet rays from the sun that are harmful to the human body and prevents them from reaching the earth's surface, has been destroyed by perchlorofluorocarbons such as fluorocarbon gas R-12. The United Nations Environment Program (UNEP) is planning worldwide regulations on fluorocarbons.

For this reason, composite hoses have been proposed in which a gas barrier layer made of polyamide resin is placed inside the inner tube rubber layer in order to prevent the leakage of fluorocarbon gas, even for refrigerant transport hoses used in the piping of automobile air conditioners, etc. There is. On the other hand, with the recent improvement in the service life of automobiles, it has become necessary to suppress the permeability of moisture from the atmosphere into the circuit through the refrigerant transport hose more than ever before. this is,
For refrigerant transport hoses used in automobile air conditioners,
This is because if moisture enters the air conditioner circuit, it may freeze in circuits such as the evaporator, block the circuit, or enter the circuit and cause hydrolysis of the polyamide resin.

Therefore, in order to suppress moisture permeation, butyl rubber and C5M are used as constituent materials for the inner tube rubber layer.

It has been proposed to use rubber compositions such as EPDM%CPE.

[Invention tries to solve 3! ! ! ! ] Among the above rubber compositions, the one with the lowest moisture permeability is butyl rubber. For adhesion between butyl rubber and polyamide resin,
Conventionally, Hypalon adhesives (for example, Chemlock 252
, 250), etc., but these adhesives usually have a high elastic modulus. For this reason, when a pose made by bonding butyl rubber and polyamide resin with a Hypalon adhesive is subjected to an impulse test, which is a measure of durability, cracks occur in the adhesive layer, and cracks occur in the polyamide resin starting from the cracks. do. For these reasons, ordinary Hypalon adhesives are unsuitable as interlayer adhesives for refrigerant transport hoses.

The present invention has been made in view of the above-mentioned conventional situation,
It is an object of the present invention to provide a refrigerant transport bowl which has low permeation of fluorocarbon gas and moisture and has excellent durability.

[Means for Solving the Problems] The refrigerant transport hose of the present invention includes an inner pipe layer in which a gas barrier layer and a rubber layer are bonded together via an adhesive layer. Is the shear modulus at room temperature 1 x 109 dyne/crr? It is characterized by the following:

The present invention will be explained in detail below.

In the present invention, the shear modulus of the adhesive layer that adheres the gas barrier layer and the inner tube rubber layer at room temperature is 1 x 109d.
If it exceeds yne/cm', a sufficient durability improvement effect cannot be obtained. If the shear modulus is too low, sufficient adhesive force cannot be obtained, so the shear modulus of the adhesive layer at room temperature is lXl0' to lXl09 dyne/cm', especially 1 x
It is preferable that it is 108-1 x 109 dyne/cm'.

Moreover, if the thickness of this adhesive layer is too thick, a sufficient durability improvement effect cannot be obtained. Therefore, it is preferable to keep the thickness of the adhesive layer as thin as possible to ensure sufficient adhesive strength, and in normal cases, the thickness after drying is approximately 0.1 to 4 μm.
In particular, it is preferable to set the thickness to about 0.2 to 3 μm.

In the present invention, the gas barrier layer may be made of a resin having excellent resistance to refrigerant permeation, and its constituent materials include, for example, polyamide resin, polyvinylidene chloride, and the like. In the present invention, the thickness of the gas barrier layer is 0.05 to 0.3 m from the viewpoint of moisture permeation resistance and flexibility.
It is preferable to set it to about m.

In addition, the material of the rubber layer is preferably low moisture permeability Ifthyrcom, C3M, EPDM, CPE, etc., butyl rubber is particularly preferred, and its thickness is 1 to 4 mm, especially 1 It is preferable to set it as .5-3.5 mm.

Note that the type of adhesive is not particularly limited, and is appropriately selected depending on the materials of the gas barrier layer and rubber layer to be bonded. Therefore, when adhering a gas barrier layer made of polyamide resin and a rubber layer made of butyl rubber, use a Hypalon adhesive and the shear modulus of the adhesive layer is 1 x 1.
09dyne/crr? It is preferable to use the following:

Incidentally, the conventionally used Hypalon adhesive is Chemlock 250, and the shear modulus of these adhesive layers is 5 dyne/cm" or more and 109 dyne/c
less than rd.

The refrigerant transport hose of the present invention has the same structure as a conventional refrigerant transport hose, except that the inner tube layer has a gas barrier layer and a rubber layer bonded together via a specific adhesive layer. I can do it.

For example, a structure may be employed in which a reinforcing layer and an outer covering rubber layer are laminated on an inner tube layer formed by bonding a gas barrier layer and a rubber layer (inner tube rubber layer) with an adhesive layer. Furthermore, an intermediate rubber layer can be provided between the outer covering rubber layer and the reinforcing layer, and
It is also possible to have two or more reinforcing layers.

The reinforcing layer may be a layer in which W4 fibers made of vinylon, polyester, nylon, aramid, or the like are coated in a spiral or braided structure. The intermediate rubber layer can be a layer of butyl rubber or the like. Further, the outer covering rubber layer can be formed of a rubber layer such as EPDM or chloroprene. And the thickness of the reinforcing layer is 1.2~2mm
The thickness of the intermediate rubber layer may be 0.2 to 0.6 mm, and the thickness of the outer rubber layer may be 1 to 2 mm.

[Function] The shear modulus of the adhesive layer that adheres the gas barrier layer and the inner tube rubber layer at room temperature is I x 109 dyne/am'
If it is below, there will hardly be any cranking in the adhesive layer even in an impulse test, and therefore a hose for transporting refrigerant with excellent durability will be provided.

[Examples] Examples and comparative examples are given below to illustrate the present invention more specifically, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Examples 1-4. Comparative Examples 1 to 5 Refrigerant transport hoses having the following configurations were manufactured, and the impulse test described below was conducted on each hose to examine the impulse test life. Further, the state of destruction of the adhesive layer after 1000 impulse tests was examined by electron microscopic observation.

The results are shown in Table 1.

Hose structure for Reimorane X Gas barrier layer: polyamide resin Thickness 100μm Adhesive layer: Hypalon adhesive Shear modulus and average thickness after drying are As shown in Table 1.

Inner tube rubber layer Nibutyl rubber thickness 1.6mm Reinforcement layer: vinylon fiber, spiral structure thickness 1.5mm Outer rubber layer: EPDM thickness 1.2mm Impulse test repeated Attach the hose to the pressure tester and run 70 times/min A pressure of 0 to 30 kgf/ei was repeatedly applied, and the number of times until bursting was recorded.

Note that 5AE5W-30 (shell formula X SG) was used as the hydraulic oil, and the ambient temperature and hydraulic oil temperature were 120°C.

From Table 1, the following is clear.

When adhesive layers of the same thickness are provided (Example 1.2, Comparative Example 1.2), the shear modulus of the adhesive layer is 1 x 109d.
If it exceeds yne/cm', early failure will occur in the impulse test. In addition, when samples were taken out after a certain number of impulse tests and the cross-section of the interface including the adhesive layer was observed using an electron microscope, it was found that cracks first appeared in the adhesive layer, which became the starting point for failure. It has been found.

Moreover, this crack is caused by the shear modulus of the adhesive layer being I
Occurs when exceeding 109 dyne/crd, but 1 x
It has also become clear that this phenomenon does not occur below 109 dyne/cm''.

In addition, the shear modulus is 8.75x 10' dyne/c
When rrIf is the same (Examples 1, 3, 4, Comparative Examples 3-
5) If the thickness of the adhesive layer is 5 μm or more, the impulse test life is slightly reduced.

E. Effects of the Invention As detailed above, the refrigerant transport hose of the present invention provides a refrigerant transport hose that has good refrigerant permeation resistance and moisture permeation resistance, and has significantly improved durability. be done.

Such a refrigerant transport hose of the present invention is extremely useful as piping for an automobile air conditioner.

Claims (1)

[Claims] (1) In a refrigerant transport hose comprising an inner tube layer in which a gas barrier layer and a rubber layer are bonded via an adhesive layer, the adhesive layer has a shear modulus of elasticity of 1 x 10^9 dy at room temperature.
A hose for transporting a refrigerant, characterized in that the refrigerant is less than ne/cm^2.