JP2703932B2 - Monochlorodifluoromethane gas low permeability hose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a low-permeability monochlorodifluoromethane gas having a balanced practical performance for transporting a refrigerant such as freon gas or transporting a fuel such as gasoline or light oil. About hoses.

<Prior art> Conventionally, as a hose used for the above-described refrigerant transportation or fuel transportation, an inner tube of the hose is made of rubber having oil resistance and low permeability of refrigerant and fuel, for example, nitrile rubber. A formed hose, a hose in which the inner tube is formed from two layers of rubber and resin, and the like have been proposed.

By the way, Freon gas, especially dichlorodifluoromethane (hereinafter, referred to as CFC12) is generally used as a refrigerant for a cooler attached to a vibrating object such as a car cooler.
Has been used. However, CFC12 destroyed the ozone layer,
It became clear that skin cancer was induced,
The use of CFC12 has been banned. Therefore,
It has been used as a refrigerant for stationary coolers,
There has been a move to use monochlorodifluoromethane (HCFC22), which has low ozone depletion potential, as one of the alternatives.

However, compared to CFC12, HCFC22 has a major drawback in that it easily penetrates NBR and nylon resin, which are widely used as conventional hose materials.On the other hand, when other resins are used, the stress and crack resistance required for hoses is reduced. Properties cannot be satisfied.

Therefore, a hose having low permeability of HCFC22 and having physical properties required for the hose, such as stress crack resistance and flexibility, has not been known so far.

<Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned facts, and has been made in response to an industrial demand. The present invention has low permeability to a refrigerant such as HCFC22 or a fuel such as gasoline and has a low stress resistance. -An object of the present invention is to provide a monochlorodifluoromethane gas low-permeability hose having both cracking properties and flexibility.

<Means for Solving the Problems> The present invention relates to a hose comprising an inner tube, a reinforcing layer, and an outer tube, wherein the inner tube comprises at least three layers of an inner layer, an intermediate layer, and an outer layer, and one of the layers is a nylon-based layer. A low-permeability monochlorofluoromethane gas hose characterized by comprising a resin and one of the other layers comprising an ethylene-vinyl alcohol copolymer.

Here, in a hose composed of an inner tube, a reinforcing layer, and an outer tube, the inner tube has at least three of an inner layer, an intermediate layer, and an outer layer.
A stress-crack preventing layer comprising a polyamide resin containing nylon 11 and / or nylon 12 as an essential component; an intermediate layer comprising a permeation preventing layer comprising an ethylene-vinyl alcohol copolymer; and an outer layer. Is formed of a rubber layer made of rubber, and is preferably a monochlorodifluoromethane gas low-permeability hose.

Further, in a hose comprising an inner tube, a reinforcing layer and an outer tube, the inner tube comprises at least three layers of an inner layer, an intermediate layer and an outer layer, and the inner layer of the inner tube comprises 40 to 80 parts by weight of nylon 6
And / or nylon 6.66 copolymer, 5 to 30 parts by weight of nylon 11 and / or nylon 12, and 10 to 40
It is characterized in that a stress / crack preventing layer comprising a resin composition comprising parts by weight of a polyolefin resin, an intermediate layer comprising a permeation preventing layer comprising an ethylene / vinyl alcohol copolymer, and an outer layer comprising a rubber layer comprising a rubber. Monochlorodifluoromethane gas low permeability hose is preferred.

Further, it is preferable that a nylon-based resin layer is formed between the intermediate layer and the outer layer of the inner tube.

Preferably, a polyamide / polyether copolymer layer is formed between the inner layer and the intermediate layer and / or between the intermediate layer and the outer layer of the inner tube.

In addition, a polyamide-polyether copolymer layer is formed between the inner layer and the intermediate layer and between the intermediate layer and the outer layer of the inner tube, and between the polyamide-polyether copolymer layer and the intermediate layer, It is preferable that a nylon-based resin layer is formed at least at one position between the polyamide / polyether copolymer layer and the outer layer.

 Hereinafter, the present invention will be described in detail.

In the monochlorodifluoromethane gas low permeability hose of the present invention, the inner tube has at least three layers of an inner layer, an intermediate layer and an outer layer.
Consists of layers.

The present invention is intended to combine these layers with an appropriate material so as to achieve a desired balance between stress crack resistance, low permeability of monochlorofluoromethane gas, and flexibility. Hereinafter, the configuration of each layer will be described.

The material forming the inner tube is preferably a nylon resin, an ethylene / vinyl alcohol copolymer, a rubber, and a polyamide / polyether copolymer.

Table 1 shows typical properties of each of the above materials. Table 1 shows that the ethylene / vinyl alcohol copolymer is excellent not only in the impermeability of dichlorodifluoromethane gas but also in the impermeability of monochlorodifluoromethane gas.

The monochlorodifluoromethane gas low-permeability hose of the present invention is formed by combining the properties of each material, and particularly has an ethylene-vinyl alcohol copolymer as a permeation preventing layer.More preferably, the inner layer of the inner tube is The stress crack preventing layer, the intermediate layer is a permeation preventing layer, and the outer layer is a rubber layer.

As is clear from Table 1, the material of the inner layer of the hose inner tube, which is the stress crack preventing layer, is a polyamide resin (nylon resin b) containing nylon 11 and / or nylon 12 as an essential component. Is preferred,
Alternatively, a resin composition comprising 40 to 80 parts by weight of nylon 6 and / or nylon 6.66 copolymer, 5 to 30 parts by weight of nylon 11 and / or nylon 12, and 10 to 40 parts by weight of polyolefin resin (Nylon resin c)
It is preferable that

Specific examples of the polyamide-based resin (nylon-based resin b) containing nylon 11 and / or nylon 12 as an essential component include nylon 11 and nylon 12 alone or mixed resin, and 60% by weight or more of nylon 11 and / or Blend polymers of nylon 12 with less than 40% by weight of other polyamide-based resins, for example, nylon 6, and the like.

Also, a resin composition comprising 40 to 80 parts by weight of nylon 6 and / or nylon 6.66 copolymer, 5 to 30 parts by weight of nylon 11 and / or nylon 12, and 10 to 40 parts by weight of polyolefin resin In (nylon-based resin c), the polyolefin may be an α-olefin copolymer, and specific examples of the polyolefin include polyethylene, polypropylene, and ethylene / propylene copolymer.

If necessary, other additives such as an antioxidant may be added to the resin composition (for example, 0.03 to 0.5% by weight of a heat-resistant agent and 3 to 10% by weight of a plasticizer).

In addition, the above compounding ratio is such that the resin composition has a stress-resistant property.
It is limited in order to have both cracking properties and flexibility.

As is apparent from Table 1, the material of the hose inner tube serving as the permeation preventing layer is preferably an ethylene / vinyl alcohol copolymer, which is preferably used as the intermediate layer.

Specific examples include EVAL EP-F101 and EVAL EP, which are random copolymers of ethylene and vinyl alcohol.
-H101, EVAL EP-E105 (both manufactured by Kuraray Co., Ltd.)
And the like.

The rubber used as the outer layer of the hose inner tube, which contributes to flexibility, generally uses a rubber composition.

Specifically, acrylonitrile-butadiene rubber (NB
R), chlorosulfonated polyethylene (CSM), ethylene-propylene-diene terpolymer rubber (EPDM), butyl rubber (IIR), chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), hydrin rubber (CHR, CHC),
Rubber compositions such as acrylic rubber (ACM) can be mentioned, and considering the balance of the hose properties with the inner layer and the intermediate layer, oil resistance, moisture impermeability, etc., NBR, CSM, EPDM,
Rubber compositions of CHR, CHC, IIR, Cl-IIR, Br-IIR are preferred.

The rubber composition contains a vulcanizing agent, a filler, a reinforcing agent, a plasticizer, an antioxidant, and the like, in addition to the rubber.
Vulcanization accelerator, softener, tackifier, lubricant, peptizer,
A dispersant, a processing aid and the like may be blended.

The hose inner tube is made of a polyamide resin (nylon resin a) containing nylon 6 and / or a nylon 6.66 copolymer as an essential component, and nylon resins a and b in Table 1 as other materials. It is also preferable to use a polyamide resin (nylon resin d) and a polyamide / polyether copolymer other than those shown as c.

Polyamide resins containing nylon 6 and / or a nylon 6.66 copolymer as an essential component have been used extensively as hose inner tube materials because of their low permeability to CFC12. 6, nylon 6
· 66 copolymers alone or mixed resins, etc .;

Other polyamide resins (nylon resin d) include, for example, nylon 8, nylon 10, and nylon 610.
And the like.

The polyamide / polyether copolymer is a block copolymer composed of a polyamide segment and a polyether segment, and the polyamide segment is composed of nylon 6, nylon 11, nylon 12, nylon 6.66 copolymer, and nylon 6.12. From the copolymer and the like, the polyether segment is composed of polytetramethylene glycol, polypropylene glycol, polyethylene glycol and the like.

By combining the components of the polyamide segment and the polyether segment, copolymers having various degrees of flexibility, melting point and oil resistance have been obtained.

As specific examples, PEBAX 5533ST01, PEBAX5562MA00, P
EBAX 5512MN00 (all manufactured by Atochem Co., Ltd.) and DAIAMID-PAE E47 (Daicel Huls Co., Ltd.).

In the present invention, the polyamide-polyether copolymer is used mainly for improving interlayer adhesion, which is considered to be because the polyamide-polyether copolymer has good wettability to resin and rubber and also has good chemical affinity. .

As described above, in the monochlorodifluoromethane gas low-permeability hose of the present invention, the inner layer of the inner tube is made of a polyamide resin containing nylon 11 and / or nylon 12 having stress crack resistance as an essential component (a nylon resin). b) or 40 to 80 parts by weight of nylon 6 and / or
Alternatively, a resin composition (nylon resin c) comprising a nylon 6.66 copolymer, 5 to 30 parts by weight of nylon 11 and / or nylon 12, and 10 to 40 parts by weight of a polyolefin resin, It is preferable that the permeable ethylene / vinyl alcohol copolymer and the outer layer are formed of a flexible rubber.

By forming an inner tube with this combination and forming a reinforcing layer and an outer layer on the outside, a book that has both the required physical properties as a hose such as stress crack resistance and flexibility and low permeability of monochlorodifluoromethane gas. The monochlorodifluoromethane gas low permeability hose of the invention is obtained.

If it is desired to increase the flexibility of the hose, the ethylene-vinyl alcohol copolymer layer (intermediate layer) should be thin.

The ethylene / vinyl alcohol copolymer is generally co-extruded with another resin. In order to make the ethylene / vinyl alcohol copolymer layer thin, for example, it is preferable to co-extrude by providing another resin layer on both sides thereof,
Therefore, between the intermediate layer and the outer layer, a nylon resin a,
As b, c and d, it is preferable to provide layers of the above-mentioned various resins, blend polymers, or polyamide / polyether copolymers.

In addition, the above-mentioned nylon-based resins a, b, c, d and ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol copolymer and rubber, and the above-mentioned nylon-based resins a, b, c, d and rubber Adhesion between them is slightly weak. On the other hand, the polyamide / polyether copolymer has good adhesiveness with any of these. Therefore, it is more preferable to provide a polyamide / polyether copolymer layer at a predetermined position between the inner layer and the intermediate layer and / or between the intermediate layer and the outer layer. Thereby, together with the structural integration of the hose inner tube, the mechanical strength, durability and the like of the hose can be improved.

Further, as a preferred example of the layer structure of the inner tube of the monochlorodifluoromethane gas low permeability hose of the present invention, a polyamide / polyether copolymer layer is provided between the inner layer and the middle and between the middle layer and the outer layer of the inner tube. A layer of nylon resin a, b, c, d is formed at least one place between the polyamide / polyether copolymer layer and the intermediate layer and between the polyamide / polyether copolymer layer and the outer layer. Are formed.

In order to increase the flexibility of the hose, the ethylene-vinyl alcohol copolymer layer of the intermediate layer is made thinner as described above. However, when the intermediate layer is thin, the inner layer, the intermediate layer, and the outer layer have three layers. In a five-layer hose inner tube in which a polyamide / polyether copolymer layer is provided between each layer in order to improve adhesiveness, the impermeability, particularly HCFC22 impermeability, may be insufficient. Therefore, in the above example, as shown in Table 1, following the ethylene-vinyl alcohol copolymer,
FC22 impermeable nylon resin a, c, d or nylon resin b layer between the polyamide-polyether copolymer layer and the intermediate layer, and between the polyamide-polyether copolymer layer and the outer layer And at least one place between them to compensate for impermeability.

As described above, the nylon-based resin layer and the polyamide / polyether copolymer layer are formed between the inner layer and the intermediate layer of the hose inner tube, and the intermediate layer and the outer layer in order to provide required properties of the hose. It is provided at a predetermined position between them, but an example of their combination and an inner tube made by combining those materials, and a hose or a JIS-1 dumbbell consisting of an inner tube, a reinforcing layer, and an outer tube manufactured by a method described later. Table 2 shows the characteristics evaluated by using.

In addition, the thickness of each layer of the inner pipe, the monochlorodifluoromethane gas low permeability hose of the present invention has the required physical properties as a hose such as stress resistance, crack resistance, flexibility, etc. and monochlorodifluoromethane gas low permeability,
The inner layer of the inner tube is 0.02 to 0.50 mm, preferably 0.05 to 0.25 mm, the middle layer is 0.005 to 0.150 mm, preferably 0.01 to 0.08 mm, and the outer layer is 0.02 to 0.50 mm, preferably 0.05 to 0.25 mm. Other layers, each 0.01 to 0.50 mm, preferably
0.02 to 0.25 mm. Inner tube (resin layer) excluding inner tube outer layer
Is 0.8 mm or less, preferably 0.5 mm or less for practical reasons.

As a method for producing the monochlorodifluoromethane gas low permeability hose of the present invention, known means can be applied.

Using multiple extruders prepared according to the type of resin,
The resin forming the inner tube of the hose is extruded from a common multi-layer extrusion head to which each extruder is connected, on a mandrel to which a release agent has been previously applied, thereby forming a resin tube having a multi-layer structure. The mandrel on which the resin tube is formed is passed through a rubber extruder, and rubber is extruded onto the resin tube to form a rubber inner tube outer layer. If necessary, a rubber layer can be formed after applying an adhesive such as a chlorinated rubber-based resin, a phenolic resin-based resin, or an HRH-based resin to the surface of the resin tube by spraying or the like.

A reinforcing yarn is braided on the inner tube formed as described above using a braiding machine, and a rubber outer tube is formed thereon using a rubber extruder. The mandrel on which the inner tube, the reinforcing layer and the outer tube are formed in this manner is heated at 130 to 170 ° C., preferably
The hose of the present invention can be obtained by heating under pressure within the temperature range of 140 to 160 ° C., vulcanizing the rubber layer, cooling, and finally pulling out the mandrel.

<Examples> The present invention will be specifically described based on examples.

The hoses having the layer constitution shown in Table 3 (Examples 1 to 20, Comparative Examples 1 to 3) were produced by the method already described, and using these hoses, the amount of permeation of the freon gas, the hose flexibility and the refrigerant were changed to resin / The adhesion durability between the resins with respect to the decrease in the adhesion between the resins, which reached the resin interface and was caused by the expansion of the refrigerant due to the temperature change, was measured and tested by the following method.

In addition, JIS No. 1 dumbbells were manufactured, and the dumbbells were used to evaluate stress and crack resistance by the following method.

 The results are shown in Table 4.

(Method of measuring freon gas permeation amount) According to JRA2001 (Japan Refrigeration and Air Conditioning Industry Association Standard) JRA standard.

The refrigerant is hosed to a fitting assembly hose with an inner diameter of 11.2 mm, a total thickness of the inner tube of 2 mm, an outer tube of 2 mm, and a hose length of 0.45 m having a reinforcing layer made of rayon between the inner tube and the outer tube. 0.6 ± 0.1 gram per 1 cm ^{3 of} internal volume. 96 to 100 ° C
After leaving for 24 hours, the weight loss (gas permeation amount) between 24 hours and 96 hours is measured, and the value is converted to g / m / 72 hours.

The leakage rate of CFC12 gas in the rubber hose is 20 to 25 g / m / 72 hours, and the refrigerant replacement cycle of the rubber hose is about two years. On the other hand, for maintenance free, the replacement cycle
10 years are needed. Therefore, for maintenance-free operation, the amount of gull leakage is reduced regardless of the type of gas.
It must be less than 5 g / m / 72 hours.

(Test Method for Stress Crack Resistance) Stress crack is a stress crack phenomenon of a resin material generated by metal ions (especially zinc ions) eluted from a pipe or metal ions present in lubricating oil.
It is known that chlorides of metal ions, especially zinc chloride, affect stress cracks.

50% on JIS-1 dumbbell (using extruded tube)
An aqueous solution of zinc chloride was added dropwise and left in an atmosphere at 100 ° C.
Observation and dropping are repeated every 4 hours, and the number of days until a crack occurs at the center of the dropping point is evaluated.

The number of days of occurrence of cracks in the resin hose tube using the nylon 6 type inner tube is 2 to 2.5 days, and the refrigerant replacement cycle of the resin hose tube is about 2 years. On the other hand, a replacement cycle of 10 years is required for maintenance-free operation. Therefore, in order to be maintenance-free, it is necessary that the number of crack occurrence days is 13 days or more.

(Test method for hose flexibility) The inner diameter is 11.2 mm, the total thickness of the inner tube is 2 mm, the outer tube is 2 mm, and a hose with a reinforcing layer made of rayon between the inner and outer tubes is used. The hose is bent along an arc having a radius of and the bending stress is measured. The bending radius is 10 times the outer diameter of the hose.
The measurement is started at a magnification of 10 times (10D), and the bending stress is measured up to 3 times (n = 2).

From the curve obtained by plotting the relationship between the bending stress and the bending radius obtained as a result, a numerical value at a specified radius (4 times) is read.

Generally, the flexibility of a rubber hose is at a level of 2.1 kgf, and some hoses having a resin tube structure are at a level of 6 to 7 kgf.

In the case of a hose with such a resin tube structure, workability is clearly poor when attaching the hose to equipment in a narrow space such as an engine room, and empirically, workability is good if the bending stress is 3.5 kgf or less. Become.

The vibration absorption also has a correlation with the flexibility, but this relationship is non-linear, and when the bending stress becomes about 3.5 kgf or more, the reaction force rapidly increases and the vibration absorption becomes extremely poor. Therefore, the bending stress of the hose is preferably 3.5 kgf or less.

(Test Method for Bond Durability Between Resins) This is a method for testing the bond durability between resins when a refrigerant is passed through a hose.

Freon is a gas at high temperatures but liquid at low temperatures. When the freon causes a phase change of the gaseous liquid in accordance with the temperature change, the pressure in the hose changes, and in a hose having poor adhesion between resins, blisters are generated early and delamination occurs.

 The test method is as follows.

The inner diameter of the inner tube is 11.2 mm, the total thickness of the inner tube is 2 mm, the outer tube is 2 mm, and a fitting assembly hose having a reinforcing layer made of rayon between the inner tube and the outer tube has a refrigerant / refrigerator oil = 100/15 The above composition was put in an amount of 70% of the volume in the hose, and both ends of the hose were closed. After leaving it at high temperature (120 ° C) for 48 hours,
C) for 12 hours. One cycle of each of high temperature and low temperature (total of 60 hours) is regarded as one cycle, and the evaluation is performed by the number of cycles until blisters are generated.

Empirically, for maintenance free, it is necessary that the number of cycles before blistering is 10 or more.

As is evident from Table 4, the monochlorodifluoromethane gas low-permeability hoses of the present invention all have low HCFC22 permeability, and have sufficient stress-crack resistance, flexibility, and sufficient resin-bonding durability. I have. Therefore, the car
When used as a hose for transporting a refrigerant such as a cooler, it can be maintenance-free.

On the other hand, conventional hoses have high permeability to HCFC22 and cannot be said to have sufficient performance in terms of stress crack resistance and flexibility.

<Effect of the Invention> According to the present invention, it is possible to obtain a monochlorodifluoromethane gas low-permeability hose having impermeability, stress crack resistance, and flexibility.

The monochlorodifluoromethane gas low permeability hose of the present invention has not only low permeability of fuel such as gasoline, but also
Although the destructive power of the ozone layer is small, HCFC22, which had not been able to be used as a refrigerant for coolers attached to vibrating objects such as cars and coolers, was low because there was no resin to prevent its permeation. So it is clear that the ozone layer will be destroyed
HCFC22 can be used as an alternative refrigerant to CFC12.

Claims (11)

(57) [Claims] 1. A hose comprising an inner tube, a reinforcing layer and an outer tube, wherein the inner tube comprises at least three layers of an inner layer, an intermediate layer and an outer layer, one of which comprises a nylon resin, A monochlorodifluoromethane gas low permeability hose characterized in that one layer is made of an ethylene / vinyl alcohol copolymer. 2. A hose comprising an inner tube, a reinforcing layer and an outer tube, wherein the inner tube comprises at least three layers of an inner layer, an intermediate layer and an outer layer, and the inner layer contains nylon 11 and / or nylon 12 as an essential component. Stress crack prevention layer comprising a polyamide resin,
A low permeability hose for monochlorodifluoromethane gas, characterized in that a permeation preventing layer made of a vinyl alcohol copolymer and said outer layer are formed of a rubber layer made of rubber. 3. The hose of claim 2, wherein a nylon resin layer is formed between an intermediate layer and an outer layer of the inner tube. 4. The monofluorofluoromethane gas low permeability according to claim 2, wherein a polyamide / polyether copolymer layer is formed between the inner layer and the intermediate layer or between the intermediate layer and the outer layer of the inner tube. hose. 5. A low-permeability monochlorofluoromethane gas according to claim 2, wherein a polyamide / polyether copolymer layer is formed between the inner layer and the intermediate layer and between the intermediate layer and the outer layer of the inner tube. hose. 6. The polyamide / polyether copolymer according to claim 2, wherein a polyamide / polyether copolymer layer is formed between the inner layer and the intermediate layer and between the intermediate layer and the outer layer of the inner tube. Between the layer and the intermediate layer, and between polyamide and
A low-permeability monochlorofluoromethane gas hose having a nylon-based resin layer formed in at least one place between a polyether copolymer layer and an outer layer. 7. A hose comprising an inner tube, a reinforcing layer, and an outer tube, wherein the inner tube comprises at least three layers of an inner layer, an intermediate layer, and an outer layer, and the inner layer of the inner tube comprises 40 to 80 parts by weight of nylon 6 And / or nylon 6.66 copolymer, 5 to 30 parts by weight of nylon 11 and / or nylon 12, and 10
A stress / crack preventing layer comprising a resin composition comprising a polyolefin resin of up to 40 parts by weight, an intermediate layer comprising a permeation preventing layer comprising an ethylene / vinyl alcohol copolymer, and an outer layer comprising a rubber layer comprising a rubber. Monochlorodifluoromethane gas low permeability hose characterized by the following. 8. The hose of claim 7, wherein a nylon-based resin layer is formed between an intermediate layer and an outer layer of said inner tube. 9. The monofluorofluoromethane gas low permeability according to claim 7, wherein a polyamide / polyether copolymer layer is formed between the inner layer and the intermediate layer or between the intermediate layer and the outer layer of the inner tube. hose. 10. The polyamide tube according to claim 7, wherein said polyamide tube is provided between said inner layer and said intermediate layer and between said intermediate layer and said outer layer.
A monochlorodifluoromethane gas low permeability hose having a polyether copolymer layer formed thereon. 11. The polyamide / polyether copolymer layer according to claim 7, wherein a polyamide / polyether copolymer layer is formed between the inner layer and the intermediate layer and between the intermediate layer and the outer layer of the inner tube. And the middle layer, and polyamide /
A low-permeability monochlorofluoromethane gas hose having a nylon-based resin layer formed in at least one place between a polyether copolymer layer and an outer layer.