JP3208921B2 - Hose for transporting refrigerant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant transport hose suitable as a refrigerant transport piping hose for a car cooler or an air conditioner of an automobile.

[0002]

2. Description of the Related Art
As a refrigerant transport hose, a composite hose in which a gas barrier layer made of a resin layer is arranged inside an inner tube rubber has been proposed for the purpose of preventing gas leakage of Freon as a refrigerant.

In this case, the resin forming the resin layer includes:
(A) Freon R-134a gas barrier property, (b) flexibility enough to be used as a hose, (c) resistance to high temperature refrigerating machine oil flowing in piping (heat resistant oil resistance), (d) high temperature in engine room The ability to withstand the conditions (heat resistance) is required.

In recent years, in order to satisfy these performances, it has been proposed to use a resin which has been subjected to the following treatment for a resin layer. (1) Blend an olefin resin such as an ionomer with a nylon resin. (2) Blend an acid-modified ethylene-propylene rubber (EPR) or an acrylic elastomer having reactivity with an amide group or a carboxyl group in nylon with a nylon resin.

However, although the method (1) can impart flexibility to the nylon, the ionomer melts at around 100 ° C., which is the actual operating temperature range of the resin. In addition, the ionomer is easily attacked by polyalkylene glycol (PAG) oil, which is a refrigerating machine oil for Freon R-134a.

In the method (2), the diffusion coefficient and the solubility of all elastomers except for the butyl rubber in the Freon R-134a gas are extremely large at 100.degree. When the elastomer is mixed in a large amount, the gas barrier property of the resin is deteriorated. Furthermore, EPR has good heat resistance PAG property but is inferior in heat resistance, and acrylic elastomer has good heat resistance but swells in PAG at high temperature, and is inferior in heat PAG property. Have.

As described above, even if a gas barrier layer is formed from the above-described resin, a hose for transporting a refrigerant having sufficiently satisfactory performance cannot be obtained.

[0008] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a refrigerant transport hose excellent in CFC R-134a gas barrier properties, flexibility, heat-resistant oil resistance and heat resistance, and excellent in high-temperature durability fatigue resistance.

[0009]

According to the present invention, in order to achieve the above object, the innermost layer comprises a sea phase mainly composed of a nylon resin, isobutylene and paramethyl in which a part of hydrogen atoms in the molecule are halogenated. Resin having a sea-island structure with an island phase containing a crosslinked product of a copolymer of styrene (hereinafter abbreviated as halogenated IB-PMS copolymer) with a crosslinking agent such as zinc white The present invention provides a refrigerant transport hose formed of a layer.

[0010]

The refrigerant transporting hose of the present invention has the following effects because the innermost layer is formed of a resin layer having a specific sea-island structure.

(1) Halogenated IB-P used for resin layer
MS copolymers have the same compatibility as conventional ionomers and acid-modified elastomers because the side chain halogen groups react with the amide groups in the nylon resin. Excellent in nature.

(2) The halogenated IB-PMS copolymer can provide flexibility higher than that of a conventional acid-modified elastomer due to its molecular structure having a structure similar to that of butyl rubber, and has a practical use temperature. R-13 around 100 ℃
4a The gas permeability coefficient is as small as 1/5 to 1/10 of that of a conventional olefin resin or elastomer.

For this reason, the hose of the present invention is excellent in flexibility and has a reaction force of 2.2 k in a hose flexibility test described later.
g · f or less, and the workability of attaching hoses and pipes is high.

In addition, the 100% modulus of the inner tube rubber is 2
0-60kg / cm^Two 100% modulus of outer rubber
15-60 kg / cm^TwoUnder the conditions, hose and piping
If the goal is to improve the workability of installing
The target value of the reaction force measured by the above test method is the hose size
It is as follows separately.

In the case of a hose having an inner diameter of 11 mm and an outer diameter of 19 mm 2.2 kg · f or less In the case of a hose having an inner diameter of 14 mm and an outer diameter of 22 mm 3.4 k
g · f or less 3.5k for a hose with an inner diameter of 15mm and an outer diameter of 23mm
g / f or less 6.4k for a hose with an inner diameter of 19mm and an outer diameter of 27mm
g ・ f or less

Further, the hose of the present invention comprises Freon R-134.
(a) The refrigerant leakage is small, and the gas permeation amount is 4 g / m / 72Hr or less in the gas permeation resistance test described later.

(3) Due to the above-mentioned molecular structure, the halogenated IB-PMS copolymer hardly swells in PAG even at high temperatures due to a large difference in polarity from PAG oil, Excellent in nature. For this reason, the hose of the present invention is resistant to PAG refrigerating machine oil flowing in the piping, and does not crack the inner layer resin.

(4) The operations of (1) to (3) are as follows.
It can also be achieved in uncrosslinked halogenated IB-PMS copolymers. However, the uncrosslinked halogenated IB-PMS copolymer has no problem in durability fatigue under ordinary temperature conditions lower than 140 ° C., but the halogenated IB-PMS copolymer exists in the nylon 6 in an uncrosslinked state. 140 ° C
When the high temperature endurance fatigue was evaluated by a high temperature impulse test in which pulse-like repetitive strain was applied under such a high temperature, the halogenated IB-PMS copolymer caused a molecular flow in nylon 6, and therefore, an interface with nylon 6 Cracks may occur due to the load, and the hose may be broken through the cracks. In contrast, halogenated IB-P
When an MS copolymer is used in combination with a crosslinking agent thereof, for example, zinc white, the halogenated IB-PMS copolymer undergoes a heteromolecular reaction between a side chain halogen group and an amide group in the nylon resin to react with the nylon. At the same time as having appropriate compatibility, a crosslinking reaction is caused in the molecule (halogenated IB-PMS molecules) by blending a crosslinking agent with the unreacted halogen group with nylon. The resulting polymer alloy is finely dispersed as soft crosslinked elastomer particles as an island phase,
Even at high temperatures, the halogenated IB-PMS copolymer molecules do not fluidize due to the presence of the strong crosslinks, and can maintain the same morphology as at low temperatures. It is greatly improved as compared with the case where the PMS copolymer is used.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a hose for transporting refrigerant according to one embodiment of the present invention. In this hose, an inner tube layer 3 composed of a resin layer 1 and an inner tube rubber layer 2 has an intermediate rubber layer 4 containing a reinforcing thread. It is covered with a jacket rubber 5 through the intermediary. In addition,
The hose has a resin layer 1 and an inner tube rubber layer 2 if necessary.
And an adhesive layer can be provided therebetween.

In the present invention, the resin layer, which is the innermost gas barrier layer, has a sea phase composed of a nylon resin such as nylon 6 or nylon 66 and an island phase composed of a halogenated IB-PM.
It is formed of a resin having a sea-island structure composed of an S copolymer alone or a mixture of the copolymer and a nylon resin such as nylon 12 further added with a crosslinking agent such as zinc white.

Here, in the halogenated IB-PMS copolymer, isobutylene and a part of hydrogen atoms in the molecule are substituted by halogen atoms such as bromine atom and chlorine atom as described in JP-A-2-150408. And a brominated IB-PMS copolymer. Although the halogenation ratio is not particularly limited, the halogen content in the paramethylstyrene molecule is 10 to 80.
% (% By weight, the same applies hereinafter), particularly preferably in the range of 20 to 70%. If the content is less than 10%, the compatibility with nylon may deteriorate, and if it exceeds 80%, the heat resistance may deteriorate.

Further, the polymerization ratio of isobutylene and paramethylstyrene is preferably 2 to 20% (weight%, the same applies hereinafter) of paramethylstyrene, particularly preferably 5 to 10%. When the polymerization ratio of paramethylstyrene exceeds 20%, Tg (glass transition point) becomes high, and the properties of the rubber may be lost. On the other hand, when it is less than 2%, the crosslinking efficiency may be deteriorated.

Further, in the above resin, halogenated IB-
The blending ratio of the PMS copolymer is based on the total amount of the nylon resin (the total amount of the nylon resin such as nylon 12 in the sea phase and the island phase when the nylon resin such as nylon 12 is mixed) and the copolymer. On the other hand, it is desirably 15 to 40%. If the compounding ratio is less than 15%, sufficient flexibility may not be provided, and if it exceeds 40%, halogen R
-134a The gas permeability increases, which may result in poor cooling capacity and the need to replenish the refrigerant several times.

When nylon 12 is blended in the island phase, the blending ratio of nylon 12 is 5 to 20% based on the total amount of all nylon resin and halogenated IB-PMS copolymer.
It is preferable that

Next, zinc white is preferably used as a crosslinking agent. In addition to zinc white, sulfur, sulfur chloride, alkylphenol disulfide, tetrakis-2-ethylhexylthiuram disulfide (TEHT), tetrakis-
1-isopropylpentylthiuram disulfide, tetrakis-1-ethyl-3-methylpentylthiuram disulfide, tetrakis-1-ethylhexylthiuram disulfide, tetraoctylthiuram disulfide (T
OTD), other organic sulfur-containing compounds, metal oxides, quinone dioximes, organic polyamines, modified phenol resins and the like are also used. The amount of the crosslinking agent required for crosslinking is 0.5 to 5% based on the halogenated IB-PMS copolymer.
In particular, it is preferably set to 0.5 to 2%. The blending amount is 0.
If the amount is less than 5%, the crosslinking reaction hardly occurs, so that the high-temperature durability may not be improved. If the amount exceeds 5%, the crosslinking is sufficiently performed, but an extra crosslinking agent is mixed in the nylon. In some cases, nylon is deteriorated, and improvement in high-temperature durability is not observed.

Further, in addition to zinc white, a crosslinking aid (accelerator)
May be added, for example, EZ (Zinc diet)
yl dithiocarbamate), TS (Te
tramethylthiuram monosulf
ide), TRA (Dimethyldiphenyl)
thiuram disulfide), MBT (2-
Mercaptobenzothiazole, MB
TS (Dibenzothiazyl disulfi)
de), NOBS (N-oxydiethylene-
benzothiazyl-sulfenamide
e), Barnock R (manufactured by Ouchi Shinko Chemical Co., Ltd.) and the like are preferably used.

The amount of the crosslinking aid is not particularly limited, but is preferably 0.5 to 3%.

In the above resin, if necessary, additives such as a heat-resistant agent, an anti-aging agent and a processing aid may be added to the sea phase or the island phase in addition to the nylon resin and the halogenated IB-PMS copolymer. Can be added in a range that does not hinder.

In the present invention, such a resin can be produced, for example, by the following method. . (1) A master batch is prepared by kneading nylon 6 and a halogenated IB-PMS copolymer or a halogenated IB-PMS copolymer, nylon 12 and a cross-linking agent at a predetermined blending ratio. Knead nylon 6. (2) nylon 6, halogenated IB-PMS copolymer,
A crosslinking agent and, if necessary, nylon 12 are blended, and this blend is kneaded with a twin-screw extruder or the like.

The other structure of the refrigerant transport hose of the present invention is not particularly limited, and a normal refrigerant transport hose configuration can be employed. For example, in the refrigerant transport hose shown in FIG. 1, the rubber constituting the inner tube rubber layer 2 is acrylonitrile butadiene rubber (NBR), ethylene-propylene-diene terpolymer (EPD).
M), butyl rubber (IIR), chloroprene rubber (C
R), chlorinated butyl rubber (Cl-IIR), hydrogenated N
BR (H-NBR), a halogenated IB-PMS copolymer, or a rubber obtained by blending at least two types of these rubbers can be used.

Further, in the intermediate rubber layer 4 containing the reinforcing yarn, a fiber made of a material such as vinylon, polyester, nylon, or aramid can be used as the reinforcing yarn, and the fiber can be coated with a spiral or blade structure. it can. The intermediate rubber layer can be a layer such as butyl rubber. In addition, as for the reinforcing yarn, the rubber layer may be omitted and only the reinforcing yarn may be stacked.

The outer rubber 5 is made of, for example, EPDM, C
R, H-NMR, halogenated IB-PMS copolymer, I
It can be formed by a rubber layer such as IR and CL-IIR.

In the present invention, the resin layer 1 has a thickness of 0.05 to 0.3 mm in consideration of the balance between the Freon transmission resistance and the flexibility.
It is preferable to set the degree. It is preferable that the inner tube rubber layer 2 has a thickness of 1 to 4 mm in view of a balance between moisture permeability and flexibility. Further, the thickness of the intermediate rubber layer 4 including the reinforcing yarn is 1.4.
It is preferable that the thickness of the outer rubber 5 is 1 to 2 mm.

Hereinafter, the present invention will be described more specifically with reference to experimental examples. The components used for the inner tube rubber, the intermediate rubber, and the outer rubber are as shown in Tables 1 to 3, respectively. However, the symbols in the table indicate the following. IIR = butyl rubber EPDM = ethylene-propylene-diene terpolymer DM = Noxeller DM (Ouchi Shinko Chemical Co., Ltd.) TT = Noxeller TT (Ouchi Shinko Chemical Co., Ltd.) M = Noxeller M (Ouchi Shinko Chemical Co., Ltd.) ) Barnock R = morpholine disulfide

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

Experimental Example A hose similar to the refrigerant transport hose shown in FIG. 1 was manufactured by the following method. That is, first, Table 4
Nylon 6, Nylon 12, brominated IB-PMS copolymer, zinc white, EZ (Z
inc dithyl dithiocarbama
te) was kneaded to form a masterbatch, and the masterbatch and nylon 6 were kneaded to form a pellet, and then extruded into a tube with a thickness of about 100 μ on a mandrel using an extruder to form a resin layer 1. . The nylon 6 and nylon 12 used here were grade 1030B and grade 3035B manufactured by Ube Industries, Ltd., respectively.
It is. The brominated IB-PMS copolymer is XP-50 grade 89-1 manufactured by Exxon Chemical Company.

On this, an adhesive was applied and dried as required, and the inner tube rubber layer 2 (1.5 m thick) having the composition shown in Table 1 was further added.
m, 11.0 mm inner diameter), followed by a reinforcing thread (vinylon) and an intermediate rubber layer 4 having the composition shown in Table 2, and further covering the outer rubber 5 having a composition shown in Table 3 (thickness: 1. 1m
m, outer diameter of 19.0 mm) to extrude a hose. In addition, vulcanization conditions are 140-170 degreeC and 30-120.
Went in minutes. Using the hose thus manufactured, each test was performed by the following method. The results are shown in Tables 4 to 6. (A) Gas permeation resistance 5 hoses conforming to JRA (Japan Refrigeration and Air Conditioning Industry Association standard)
It was cut into 00 mm, sealed with Freon with an internal volume of 60%, and sealed at both ends. It was left at a temperature of 100 ° C. for 96 hours, and the gas permeation amount between 24 hours and 96 hours was measured.
The numerical value was converted at 72 Hr. 4 g / m / 72 Hr or less was evaluated as ○, and a value larger than 4 g / m / 72 Hr was evaluated as x. (B) Flexibility test As shown in FIG. 2, the rollers 6 were arranged at a span of 200 mm, and the above-mentioned hose 7 was placed thereon. The central part of the distance between the rollers was pressed to bend until the hose kinked, and the maximum pressure (kg · f) generated at that time was measured. A value of 2.2 kg · f or less was evaluated as ○, and a value larger than 2.2 kg · f was evaluated as ×. (C) High-temperature impulse test The experimental conditions were based on JRA (Japan Refrigeration and Air Conditioning Industry Association Standard).
The temperature was raised, and the internal pressure was raised, under the following conditions. Oil and ambient temperature: 140 ° C. Internal pressure: 36 (kg / cm ² ) Pressurization cycle: 60 CPM Cycle number of cycles: 500,000 times and 1,000,000 times, the inside of the hose was visually inspected for cracks. The case where there was no abnormality such as crack was evaluated as ○, and the case where there was abnormality was evaluated as ×.

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Table 6]

From the results shown in Tables 4 to 6, the refrigerant transport hose of the present invention has excellent gas permeability and flexibility, and
Impulse endurance test at high temperature of 140 ° C
It was confirmed that it was able to clear 0,000 times and was excellent in high-temperature durability performance.

[0044]

The hose for transporting refrigerant of the present invention has good flexibility, good workability, and excellent gas permeation resistance.
134a has high gas barrier properties and excellent heat-resistant PAG oil properties, and is extremely excellent in high-temperature durability fatigue even under high-temperature conditions exceeding 140 ° C. Therefore, the hose of the present invention
It is suitable as a hose for a refrigerant transport pipe of an automobile car cooler or an air conditioner.

[Brief description of the drawings]

FIG. 1 is a schematic view of a hose for transporting refrigerant according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a flexibility test method in an experimental example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin layer 2 Inner tube rubber layer 3 Inner tube layer 4 Intermediate rubber layer containing a reinforcing thread 5 Outer rubber 6 Roller 7 Hose

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-B Hei 2-32515 (JP, B2) JP-B Hei 7-116339 (JP, B2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F16L 11/08 B32B 1/08 B32B 25/08 B32B 27/34

Claims (3)

(57) [Claims] 1. An inner layer comprising a sea phase mainly composed of a nylon resin, an island phase containing a copolymer of isobutylene and paramethylstyrene in which a part of hydrogen atoms in the molecule is halogenated, and a crosslinking agent. A hose for transporting refrigerant, which is formed from a resin layer having a sea-island structure. 2. The hose according to claim 1, wherein the content of the copolymer is 15 to 40% by weight based on the total amount of all the nylon resin and the copolymer. 3. The hose according to claim 1, wherein the copolymer is crosslinked by adding 0.5 to 5% by weight of zinc white as a crosslinking agent to the copolymer.