JPH01286829A - Hose for refrigerant - Google Patents

Abstract

PURPOSE:To reduce drastically permeation of a refrigerant even in case of HFC 22, by a method wherein at least one side out of an inner pipe layer and outer pipe layer is formed of polyblend of a linear polymer of specific polyamide and elastomer. CONSTITUTION:The subject hose is provided with an inner pipe layer 11 and reinforcing layer 3, outer pipe layer at need and at least the one side inner pipe layer 11 out of the inner and outer pipe layers is made specific polyblend by blending mechanically a specific linear polymer and elastomer. The specific linear polymer is a matter to be obtained by performing polycondensation of aliphatic saturated diamine and aliphatic dicarboxylic acid or polyamide having the same structure as that. Refrigerant resistant of specific polyamide is particularly favorable as compared with that of wide use polyamide. In the case where the whole of the inner pipe layer is formed of the specific polyblend, it is preferable ordinally to make the specific polyamide a compound ratio so that the same becomes a sea phase from viewpoint of fluorocarbon gas resistance and permedability of a hose.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a refrigerant hose provided with an inner pipe layer, a reinforcing layer, and optionally an outer pipe layer.

<Prior Art> Here, a refrigerant hose provided with an outer tube layer will be described as an example, but the same applies to a refrigerant hose that is not provided with an outer tube layer, that is, the reinforcing layer is the outer circumferential surface.

Generally, halogenated hydrocarbons called fluorocarbons are used as refrigerants. A conventional refrigerant hose has an inner pipe layer 1, a reinforcing layer 3,
The structure consisted of an outer tube layer 5.

Here, the inner tube layer 1 is made of synthetic rubber such as NBR, which is considered to have good refrigerant resistance (permeation resistance, shadow resistance), and the reinforcing layer 3
is made of synthetic fiber such as polyester (ex, PUT), and the outer tube layer 5 is made of synthetic rubber such as EPDM-CR-C3M, which has good weather resistance.

However, in a refrigerant hose with this configuration, the refrigerant easily permeates through the refrigerant and the refrigerant decreases during use, resulting in a significant drop in cooling efficiency. It has been proposed to form a thin cylindrical layer made of polyamide (nylon 6, nylon 11, nylon 12).

<Problems to be Solved by the Invention> However, the present inventors have investigated the above-mentioned nylon 6 and nylon 12 for Freon 22, which has a larger latent heat of vaporization than Freon 12 used in general air conditioning (the chlorine of Freon 12 is hydrogen). When the permeation resistance was measured against the material (replaced with the hose), it was found that the hose did not have sufficient permeation resistance even when the wall thickness was about 0.5 mm, which inhibited the flexibility of the hose.

(See Comparative Examples 2 and 3 in Table 1.) Therefore, in the case of a refrigerant hose for Freon 22, in order to obtain sufficient permeation resistance, the thin cylindrical layer made of polyamide must be thick (approximately 1.0 mm thick in the case of nylon 6). or above),
In order to impart flexibility, it is necessary to take measures to impart flexibility, such as corrugating the polyamide cylindrical thin layer as described in the above-mentioned publication, which is troublesome and impractical.

Means for Solving the Problems> As a result of intensive development efforts by the present inventors in order to solve the above problems, the present inventors were able to come up with a refrigerant hose having the following configuration.

In a refrigerant hose equipped with an inner tube layer, a reinforcing layer, and an outer tube layer if necessary, all or part of at least one of the inner tube layer and the outer tube layer is formed of a polyblend of a linear polymer and an elastomer. A refrigerant hose, characterized in that the linear polymer is one obtained by polycondensing an aliphatic saturated diamine having a benzene ring and an aliphatic saturated dicarboxylic acid, or a polyamide having the same structure.

<Aspects of implementation> Each aspect of the present invention is shown in FIGS. 1 to 4. Figure 1 shows inner tube layer 1.
1, the inner thin layer 11a of the inner tube layer 11 in FIG.
FIG. 3 shows the outer thin layer jib of the inner tube layer 11, and FIG. 4 shows the inner and outer thin layers 11a and ttb of the inner tube layer 11. Polyblend).

The above-mentioned specific linear polymer is an aliphatic saturated diamine having a benzene ring (hereinafter referred to as "benzene ring-containing aliphatic diamine").
) and an aliphatic saturated dicarboxylic acid, or a polyamide (
(hereinafter referred to as "specific polyamide").

That is, it has a repeating unit having the following structure.

However, R: alkylene group having 1 to 4 carbon atoms, n, m: 1
A natural number of ~4 In the above, the benzene ring-containing aliphatic diamine specifically includes ω, ω′-diaminoxylene, ω, ω′
-diaminodiethylbenzene, ω, ω'-diaminodibutylbenzene (all including 0, m, and p forms), and the like.

Furthermore, examples of the aliphatic saturated dicarboxylic acids include malonic acid, succinic acid, glutaric acid, and adipic acid.

Specific polyamides that can be used in the present invention include, for example,
It is preferable to use the one sold by Toyobo ■ under the trade name rMXD6J. This rMXD6J is obtained by condensation polymerization of ω, ω'-diaminoxylene and adipic acid.

As confirmed by the present inventors, the above-mentioned specific polyamide has much better refrigerant resistance (particularly permeation resistance) than the above-mentioned general-purpose polyamide (see examples in Table 1).

The refrigerant permeation amount in Table 1 is calculated by submerging a gas permeation cell with test pieces of 1 a+mt each in an oil bath and heating it to 80°C.After the pressure gauge shows about 40 kgf/ai', measure the gas permeation cell with a manometer. The amount of permeation when connected and the permeation rate becomes constant is calculated for one year.

The elastomer material has a flexural modulus of 10100 DO/r
It is a rubber-like or soft polymer having a weight of less than 5,000 g/co+', preferably less than 5,000 g/co+', and thermoplastic elastomers such as polyester, polyamide, polyolefin, polystyrene, and ionomer can be used. especially,
Among polyolefins, 5EBS is preferably acid-modified by graft polymerization with an aliphatic unsaturated dicarboxylic acid such as maleic acid (hereinafter referred to as "acid-modified 5EBSJ").Here, rsEBsJ refers to hard A soft segment in the middle of a polystyrene block segment is polyolefin (ethylene/butylene; EB).

Furthermore, in addition to the above-mentioned thermoplastic elastomers, examples of elastomer materials include IIR, EPDM, C5M,
Synthetic rubbers such as NR, SBR%CM%C01ECO, CR can also be used. In particular, among these synthetic rubbers,
Acid-modified EPDM as above (hereinafter referred to as "acid-modified EP")
It is called DMJ.

) is desirable.

The above specified polyamide and elastomer are mechanically blended to form a specified polyblend, but at this time, carbon black, lubricants, desensitizers, stabilizers, and other various fillers are usually added to the rubber. may be used in combination.

The blending ratio of the specific polyamide and elastomer is appropriately set depending on the performance required of the refrigerant hose (balance of refrigerant resistance, refrigerant permeation resistance, and flexibility). For example, when the entire inner tube layer is made of a specific polyblend as shown in Figure 1, from the standpoint of the hose's resistance to fluorocarbon gas permeability,
Usually, it is preferable to set the blending ratio so that the specific polyamide forms the sea phase.

In addition, as shown in Figures 2 to 4, when the thin layer is made of a specific polyblend, the thin layer has little effect on the hose flexibility, but the refrigerant permeation resistance is relatively reduced. Usually, it is preferable to set the blending ratio to be approximately half or more of the specific polyamide. Further, the method for producing the refrigerant hose of the present invention, which can be used by crosslinking part or all of the specific polyamide or specific polyblend, is as follows.

In the case of the hose shown in Fig. 1, the inner tube layer 1 is extruded by a conventional method, the reinforcing layer 3 is formed by plaiding or spiraling, the outer tube layer 5 is extruded on top of the reinforcing layer 3, and the outer tube layer 5 is extruded through a vulcanization process. do.

Note that the materials used for reinforcement/W3 are those listed above, but if higher heat resistance is required, synthetic fibers with good heat resistance such as para-aramid, aramid, carbon, and glass fiber may be used. May be used. The material used for the outer tube layer is the above-mentioned specified polyblend or the above-mentioned rubber with good weather resistance.In the case of the hose shown in Fig. 2, the extrusion head is heated and melted or kneaded with the above-mentioned specified polyblend material. After forming the inner thin layer 11a by extruding it onto a mandrel, the inner tube layer 11 is extruded by a conventional method, the reinforcing layer 3 is formed by plaiding or spiraling, and the outer tube layer 5 is extruded thereon and vulcanized. After going through the process, the mandrel is pulled out and manufactured.

Here, the thickness of the cylindrical thin layer is usually set to 0.05 to 0.5 ml11 in view of the balance between refrigerant permeation resistance and hose flexibility. In the above, the cylindrical thin layer may be formed by wrapping a tape-shaped polymeric material around the mandrel and heating and melting it in the vulcanization process. It may also be formed by pouring a molten material into the inside of a hose by dipping or otherwise cooling and solidifying the material. If it is difficult to melt and bond the cylindrical thin layer and the inner tube layer, it is desirable to interpose an adhesive layer between the two layers. The material of the inner tube I is EPDM, C3M, NR%SBR, CM%CR, I
IR, Co, ECO, etc. can be used.

In addition, the materials used for the reinforcing layer and the outer tube layer are as mentioned above, but if heat resistance is required for the reinforcing layer, heat-resistant fibers such as loose aramid, aramid, carbon, and glass fiber are used. It is desirable to use it.

In the case of the hose shown in FIG. 3, the manufacturing method is basically the same as that shown in FIG.
It is slightly different because it is above 1. That is, the specific polyblend material is extruded onto the inner tube layer 1 formed by extrusion, or
Alternatively, a thin cylindrical layer is formed by coating by dipping or the like.

In addition, in the case of this configuration, since the inner tube jilt comes into direct contact with the refrigerant, the inner tube layer material is preferably chlorinated polyethylene rubber (CM), which has excellent refrigerant swelling resistance.
In the case of the hose shown in the figure, the methods described for the hose shown in Figures 2 and 3 above may be combined as appropriate.

The location of the thin layer is not limited to the side, but can also be placed in the middle of the inner tube layer, in the reinforcing layer itself (by impregnating it), and even inside, in the middle, or outside of the outer tube layer. good.

<Operations and Effects of the Invention> As described above, the refrigerant hose of the present invention is provided with an inner pipe layer, a reinforcing layer, and optionally an outer pipe layer, in which at least one of the inner pipe layer and the outer pipe layer is provided. All or part of one is formed from a polyblend of a linear polymer and an elastomer, and the linear polymer is obtained by polycondensing an aliphatic saturated diamine having a benzene ring and an aliphatic saturated dicarboxylic acid. Or, since it is characterized by being made of a specific polyamide having the same structure as that, it exhibits the following effects.

Since the layer made of the specific polyblend is present in the inner tube layer or the outer tube layer, the permeation of the refrigerant can be significantly reduced not only when the refrigerant is Freon 12 but also when the refrigerant is Freon 22.

<Examples> Examples carried out in order to better understand the present invention will be described below together with conventional examples.

Hoses having the structure of the present invention shown in FIG. 2 or having the conventional structure shown in FIG. 5 were manufactured with the specifications shown in Table 2, and the following physical property tests were conducted on each hose.

(1) Freon gas permeability 2 Japan Refrigeration and Air Conditioning Industry Association Standards (Freon 22) JRA2001-1976
The study was conducted based on Section 5-8 (however, the test temperature was 80°C).

(2) Flexibility: From the following relationship, the amount of deflection δ was measured and the bending rigidity El was determined.

δ = amount of deflection (cn+) EI = bending rigidity (kg - country) (3) Lightness: The hose was cut into a length of 1 m, and its weight was measured.

The test results are shown in Table 2, and it can be seen that the hoses of each example exhibit far superior fluorocarbon gas permeability compared to the conventional example. Note that when the blending ratio of the specific polyamide is less than 65% (Example 3), the resistance to fluorocarbon gas permeability becomes worse than in other Examples. In addition, the combination of specific polyamide and elastomer is made into specific polyamide/acid-modified 5EBS.
In the case of (Example 5), it has a thinner wall (about 1/3) and equivalent fluorocarbon gas permeability than other combinations, specific polyamide/acid-modified EPDM (Example 4),
When the thickness of the thin layer made of the specific polyamide/acid-modified 5EBS polyblend exceeds 0.5 mm, the flexibility of the hose rapidly decreases (see Examples 2, 5, 6, and 7).

Table 1

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing refrigerant hoses according to embodiments of the present invention, and FIG. 5 is a cross-sectional view showing an example of a conventional refrigerant hose. 1.11... Inner tube layer, 3... Reinforcement layer, 5... Outer tube layer, 11a/flb... Thin layer. Patent application Toyoda Gosei Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] A refrigerant hose comprising an inner pipe layer, a reinforcing layer, and optionally an outer pipe layer, wherein the whole or part of at least one of the inner pipe layer and the outer pipe layer is made of a linear polymer. and an elastomer, and the linear polymer is one obtained by polycondensing an aliphatic saturated diamine having a benzene ring and an aliphatic saturated dicarboxylic acid, or a polyamide having the same structure. A refrigerant hose featuring: