JP2551649B2 - How to connect the hose to the fitting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for coupling a hose and a fitting having practical performance without leakage, for transporting a refrigerant such as Freon gas or for transporting a fuel such as gasoline and light oil. Regarding

<Prior Art> Freon gas, particularly dichlorodifluoromethane (hereinafter referred to as CFC12), has been generally used as a refrigerant for a cooler attached to a vibrating object such as a car cooler. However, it has become clear that CFC12 destroys the ozone layer, which causes skin cancer, and the use of CFC12 has been restricted. Therefore, trifluoromonofluoroethane (hereinafter,
It is called HFC134a. ) Is considered as one of the alternative candidates.

While it is urgent to confirm the safety of this refrigerant, there is an increasing need for a safer method of transporting the gas and to make it maintenance-free.

As a hose used for transporting a refrigerant or for transporting a fuel, an inner tube of the hose is used as a rubber having oil resistance and low permeability of refrigerant or fuel, such as NBR or CSM. More recently, in order to improve permeation resistance, a rubber / resin inner tube multi-layer structure with a thermoplastic resin such as nylon resin in the innermost layer of the hose inner tube / rubber such as NBR, CSM, IIR in the outer layer of the inner tube A hose is proposed.

<Problems to be Solved by the Invention> FIG. 1 is a cross-sectional perspective view of a typical rubber / resin composite hose used in the present invention, and FIG. 2 is a connection state of a hose and a nipple of a fitting. An example is shown.

The hose 10 includes an outer rubber layer 40, a reinforcing layer 30, and an inner rubber layer 20.
It has a multi-layered structure including b and the innermost resin layer 20a.

Further, the fitting 50 is connected to the inside of the hose with a nipple 50b, and is compressed from the outside of the hose with a socket 50a.
It is designed to crimp between 0 and the fitting.

In particular, the above-mentioned hose is provided with the thin resin layer 20a as the innermost layer, so that it has a function of significantly reducing the amount of gas permeation such as freon. However, if this thin layer resin is used for a long time at a temperature higher than the normal temperature (140 to 160 ° C), it will be stressed by the nipple part of the fitting, and the working pressure (15 to Even at 30 kgf / cm ² ) or less, there was a drawback that leakage would occur.

After aging a conventional hose at a certain temperature for a certain time and aging, pressure was applied to the hose to check whether leakage occurred (airtight test), and the results are shown in Table 1.

From this result, if the hose is left under high temperature for a long time due to an unexpected situation, gas in the hose may leak, safety, and maintenance-free may not be sufficient even if only a slight internal pressure is applied. Recognize.

As a technique to prevent this leakage, there is a method in which the shape of the fitting is trapezoidal groove, sawtooth shape and bamboo saw shape nipple, and the crimping shape of the socket is wave tightening or flat tightening. However, stable performance has not been obtained.

Further, a method of using packings such as an o-ring and a sleeve has been considered, but it is not practical because it has a drawback that it moves when the nipple is inserted into the hose.

There is also a method of applying an adhesive, but in the case of chlorinated rubber cement or the like, the resin in the innermost layer of the hose is deteriorated and cracks may occur, which may impair the leak prevention effect.

As described above, in any case, the conventional leak prevention techniques have drawbacks in reliability, easiness of processing, and cost, and have not been put into practical use.

The present invention has been made in view of the above facts and in response to industrial requirements, and in a hose having a thermoplastic resin in at least the innermost layer, a refrigerant such as CFC12 or HFC134a or a fuel such as gasoline leaks. It is an object of the present invention to provide a highly reliable method for joining a hose and a fitting without doing so.

<Means for Solving the Problems> That is, the present invention relates to a method for joining a hose having a thermoplastic resin layer as at least the innermost layer and its joint fitting, in which the innermost thermoplastic resin layer and the nipple of the joint fitting are joined together. At the joint, at least one unvulcanized rubber selected from the group consisting of chlorosulfonated polyethylene (CSM), chlorinated butyl rubber (Cl-IIR) and brominated butyl rubber (Br-IIR), and its vulcanization A method for joining a hose and a fitting, which comprises an unvulcanized rubber composition containing an agent and an organic solvent and having a minimum viscosity of 45 to 120 at 125 ° C. measured by a Mooney viscometer. Is.

Further, the unvulcanized rubber composition, with respect to the area of the joint portion of the hose and nipple, in the portion excluding the area portion of 15% from the tip of the nipple, the area of the joint portion of the hose and nipple, 15 ~ 85 It is preferable to interpose so as to cover the area of%.

It is preferable that the thermoplastic resin layer is a polyamide resin, the hose further has a chlorinated butyl rubber layer as an outer layer, has a low Freon gas permeability, and is used for refrigerant transportation. Further, these rubbers are used alone or in combination with other rubbers in some cases as long as the gist of the present invention is not impaired.

The unvulcanized rubber composition to be interposed is a cement containing the unvulcanized rubber composition.

 The present invention will be described in detail below.

As shown in FIG. 2, the bonding method of the present invention is such that an unvulcanized rubber composition 6 is provided between a hose 10 having a thermoplastic resin layer in at least the innermost layer 20a and a nipple 50b of a joint fitting 50 thereof.
Connect with 0 interposed.

The components of the unvulcanized rubber composition are the balance of properties required for the innermost layer and the hose joint with the nipple, and the oil resistance, water impermeability, gas impermeability, etc. of the unvulcanized rubber composition itself. Considering the leak prevention performance of chlorosulfonated polyethylene (CSM), chlorinated butyl rubber (Cl-I
IR) or brominated butyl rubber (Br-IIR).

The rubber composition contains a vulcanizing agent and a solvent in addition to rubber. Furthermore, fillers, reinforcing agents, plasticizers, lubricants, antioxidants, etc. are usually blended, and also vulcanization accelerators, softeners, tackifiers, antioxidants, peptizers, dispersants,
A processing aid and the like may be added, but the minimum viscosity at 125 ° C. measured by a Mooney viscometer is 45 to 120.

Although more specifically exemplified below, the unvulcanized rubber composition used in the present invention is not limited thereto.

The vulcanizing agent varies depending on the type of rubber, but in the case of CSM (chlorosulfonated polyethylene), for example, a metal oxide, a metal peroxide or an organic acid is used as the vulcanizing agent.

Specifically, magnesium oxide, lead oxide, metal oxides such as tribasic lead maleate, organic peroxides, hydrogenated rosin, resin acids such as abietic acid, and organic acids such as fatty acids such as stearic acid and lauric acid. The acid is given.

In the case of IIR (butyl rubber), modified phenol resin, quinone dioxime, alkylphenol formaldehyde resin, p-quinone dioxime, p,
p'-dibenzoylquinone dioxime, tetrachloro-
p-benzoquinone etc. are mentioned.

Fillers and reinforcing agents include carbon black, titanium oxide, white carbon (silicic acid-based fillers), inorganic fillers such as magnesium silicate and barium sulfate, and organic fillers such as phenol resin and high styrene resin. It is illustrated.

Examples of the plasticizer include dibasic acid esters, glycol derivatives, glycerin derivatives, paraffin derivatives, and epoxy derivatives, and specifically, trimellitic acid esters, dioctyl phthalate, di-n-butyl sebacate, and the like.

Examples of the lubricant include stearic acid, metallic soap of stearic acid, wax, polyethylene and the like.

The unvulcanized rubber composition used in the present invention has a minimum viscosity of 45 to 120, preferably 50 to 100 at 125 ° C by a Mooney viscometer.
Is used.

If it is less than 45, the effect of preventing leakage between the nipple and the resin of the hose after heat aging is insufficient and it cannot be put to practical use, and it is too soft and the workability is poor, and sticking to the mixer or roll occurs. , Productivity and quality stability are poor.

On the other hand, if it exceeds 120, cross-linking due to heat generation proceeds during the mixing process and so-called burns are likely to occur, so that the desired cement cannot be obtained due to the difficulty in working.

Generally, the minimum viscosity measured by a Mooney viscometer is a measure of the plasticity of an unvulcanized rubber composition, and as shown in Table 1 above, there is no leakage at 120 ° C. in the airtight test after heat aging, which is a problem. In the present invention, the minimum viscosity of 125 ° C. measured by a Mooney viscometer is used as a standard for conformity due to the flow of the unvulcanized rubber composition into the shape of the part to be interposed in the connection between the hose and the nipple in order to leak at a temperature of more than 0 ° C. Using.

When the unvulcanized rubber composition is placed at a high temperature of 125 ° C. or higher, the heat causes crosslinking to proceed, the strength of the composition is increased, and resistance to bonding and distortion between the hose and the nipple becomes stronger. On the other hand, even at a temperature below the crosslinking temperature (for example, 80 ° C.), if the unvulcanized rubber composition has a minimum viscosity of 45 ° C. at 125 ° C. measured by a Mooney viscometer, it is sufficient for the purpose of the present invention even before the crosslinking. It has sufficient bond strength and resistance to strain.

Further, the unvulcanized rubber composition, with respect to the area of the joint portion of the hose and nipple, in the portion excluding the area portion of 15% from the tip of the nipple, the area of the joint portion of the hose and nipple, 15 ~ 85 % So as to cover the area.

If it is less than 15%, the coating area ratio will be incomplete and leakage will occur easily, and if it exceeds 85%, the leakage prevention effect will be exhibited, but as a result, 15% will be covered from the tip of the nipple, so the gas inside the hose Such a fluid and the unvulcanized rubber composition come into contact with each other, the unvulcanized rubber composition dissolves in the gas (fluid), or the gas is discolored, which adversely affects the system using the hose. In the worst case, there is a risk of failure.

The method of interposing the unvulcanized rubber composition is performed by melting in an organic solvent to form a cement and applying it.

To make the unvulcanized rubber composition into a cement, a solvent such as toluene, xylene, MEK, ethyl acetate or hexane is used. The concentration may be any as long as it can be worked,
The usual concentration is preferably 5 to 50% by weight. When the unvulcanized rubber composition is applied in the form of cement, it is excellent in that a uniform thin film can be formed and the thickness can be finely adjusted easily. The thickness of the unvulcanized rubber composition coated between the nipple and the hose is preferably 0.05 mm or more and 0.2 mm or less.

If it is less than 0.05 mm, the cement-like composition in the stress concentration portion moves when the socket is crimped, and the leak preventing effect cannot be exhibited, and if it exceeds 0.2 mm, the workability of hose insertion is deteriorated, which is not preferable.

The thermoplastic resin for the innermost layer of the hose may be any as long as it serves the purpose of preventing permeation, and a hose made of nylon 6, nylon 6.66 copolymer, nylon 11, nylon 12, etc. is generally known. However, it is more preferable to use a polyamide resin containing nylon 6 and / or a nylon 6.66 copolymer as an essential component, JP-A-63-125885 and the like.

A polyamide resin containing nylon 6 and / or a nylon 6.66 copolymer as an essential component has been widely used as a hose inner tube material because of its good permeation resistance of CFC12. Nylon 6 and nylon 6/66 copolymer may be used alone or as a mixed resin.

Examples of other polyamide resins include nylon 8, nylon 10, 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 includes nylon 6, nylon 11, nylon 12, nylon 6/66 copolymer, and nylon 6/12. From a copolymer or the like, the polyether segment is composed of polytetramethylene glycol, polypropylene glycol, polyethylene glycol or the like.
Also, by combining the components of the polyamide segment and the polyether segment, various degrees of flexibility, melting point,
Copolymers having oil resistance are obtained, and these copolymers may be used.

<Example> The present invention will be described more specifically based on an example.

(Examples 1 to 7, Comparative Examples 1 to 3) Unvulcanized rubber compositions were blended in the composition as shown in Table 2, mixed with a mixing roll at 60 ° C. for 15 minutes, and analyzed by a Mooney viscometer. The minimum viscosity of the unvulcanized rubber composition at 125 ° C. was measured.

The unvulcanized rubber compositions of Examples 1 to 6 and Comparative Examples 1 to 3 used toluene as a solvent, and the unvulcanized rubber compositions of Example 7 used n-hexane as a solvent. A solvent was added so that the concentration of the rubber composition would be 30% by weight and dissolved to obtain cement. The number of times of application of cement was adjusted so that the film thickness after drying was 0.05 mm and 0.1 mm.

On the other hand, as a method for manufacturing the hose, known means can be applied.

 The method for producing the hose used in the present invention will be described below.

First, using a resin extruder, a resin (nylon 6 / nylon 11 / polyolefin) that forms the inner tube of the hose from the extrusion head on a nylon 11 mandrel with an outer diameter of 10.6 mm to which a release agent has been previously added Extruded to thickness to form a resin tube.

The mandrel having the resin tube formed was passed through a rubber extruder, and IIR rubber was extruded on the resin tube to a thickness of 2.0 mm to form a rubber inner tube outer layer.

On the inner tube formed as described above, braid polyester reinforcement yarn appropriately using a knitting structure, and using a rubber extruder on it an Cl-IIR rubber outer tube with a thickness of 1.5 mm. Formed.

Further, pressure vulcanization was performed at a temperature of 150 ° C. for 60 minutes, and after cooling, the mandrel was pulled out to manufacture a hose for use in the present invention.

The aluminum fittings used in the past were used as the fittings.

The cement is applied to a nipple, then a hose is inserted, and the socket is tightened at a pressure of 60 kgf / cm ² , whereby the unvulcanized rubber composition is interposed between the nipple and the hose innermost layer resin, and Joined fittings.

As a test of air tightness, this hose was
After allowing to stand for a period of time and cooling to room temperature, the hose was allowed to stand still in water, each pressurization as shown in Table 2 was applied, and it was visually observed whether leakage occurred.

If no leakage occurred, it was rated as O, and if leakage occurred, it was rated as X. If a leak occurred, the test was stopped there.

 The results are shown in Table 2.

(Examples 8 to 12, Comparative Examples 4 to 6) Using the cements of the unvulcanized rubber compositions of Examples 1 to 5 and Comparative Examples 1 to 3, the hose and the joint fitting were joined in the same manner as above. did.

After leaving this hose at each temperature and time condition shown in Table 3 and allowing it to stand still in water in the same manner as described above, each internal pressure shown in Table 3 was applied, and the presence or absence of leakage was evaluated in the same manner as above.

 The results are shown in Table 3.

(Examples 13 to 15 and Comparative Examples 7 to 9) The cement of the unvulcanized rubber composition of Example 3 was used and the area ratio (%) of the cement applied to the nipple was adjusted as shown in Table 4. The coating area ratio (%) is the ratio of the cement coating area to the joint area of the hose and the nipple, and the coating is applied in the tip direction of the nipple until the predetermined coating area ratio is reached, with the nipple position corresponding to the end of the hose as the base point. .

After that, the hose and the fitting were joined by the same method as described above, left standing in an atmosphere at 160 ° C. for 24 hours, and an airtight test was conducted by the same method as described above.

Furthermore, the following oil-encapsulated heat aging test and crepe test during nipple insertion were performed.

<Oil-filled heat aging test> According to the method described in JIS K6349 7.4 (2), temperature 1
It was treated at 20 ° C for 168 hours.

 Then, the oil inside was taken out and the color of the oil was visually observed.

<Meccle test when inserting nipple> A sample in which a hose is inserted into a nipple is prepared, the hose portion on the nipple of the sample is divided into two in the longitudinal direction, and the state of the unvulcanized rubber composition in the nipple portion is visually observed. did.

 The results are shown in Table 4.

Examples 1 to 5 and Comparative Examples 1 to 3 show the relationship between the minimum viscosity at 125 ° C. by a Mooney viscometer of the unvulcanized rubber composition interposed between the nipple and the hose innermost resin layer and the leakage prevention effect. It is a thing.

In Examples 1 to 5, the minimum viscosity of the unvulcanized rubber composition measured by the Mooney viscometer at 125 ° C. is within the range disclosed in the present invention, and all of them have a good leakage preventing effect.

In Comparative Examples 1 and 2, the unvulcanized rubber composition has a minimum viscosity of 125 ° C. measured by a Mooney viscometer lower than the range of the present invention, so that leakage occurs at ²⁰ to 40 kgf / cm ² , and the leakage prevention effect is insufficient. Therefore, it cannot be put to practical use.

Comparative Example 3 is an unvulcanized rubber composition obtained by removing the plasticizer having a viscosity decreasing effect from Example 5, and the minimum viscosity at 125 ° C. measured by the Mooney viscometer is obviously higher than the minimum viscosity range of the present invention. Therefore, the mixture was burned during the mixing and could not be used in the subsequent tests.

In Example 6, the unvulcanized rubber composition interposed between the nipple and the innermost resin layer of the hose was an unvulcanized rubber composition of carbon black-blended chlorosulfonated polyethylene, and Example 7 is Similarly, an unvulcanized rubber composition of butyl rubber is used. Since all of them are in the range of the minimum viscosity of 125 ° C. measured by the Mooney viscometer of the present invention, they show a good leak preventing effect.

Examples 8 to 12 and Comparative Examples 4 to 6 are for confirming the effect of the present invention under other temperature conditions and the leakage prevention limit pressure, and the Examples show good leakage at any temperature of 80 to 160 ° C. It shows the prevention effect, and the leak prevention limit pressure becomes higher as the minimum viscosity of 125 ° C measured by the Mooney viscometer becomes higher.
It is higher and supports the mechanism of action of the present invention.

On the other hand, Comparative Examples 4 to 5 have a Mooney viscometer of 125 ° C.
Since the lowest viscosity is lower than the range of the present invention, the leakage prevention effect becomes insufficient at a temperature higher than 120 ° C. Therefore, this means that the temperature measured by the Mooney viscometer of the present invention is 125
It also supports the validity of being in ° C.

In Examples 13 to 15 and Comparative Examples 7 to 9, the arrangement position and area of the unvulcanized rubber composition with respect to the nipple were examined.

Each of Examples 13 to 15 has a good leakage prevention effect, and does not cause discoloration of the oil or cause clogging at the time of inserting the nipple to impair workability or reliability of the leakage prevention effect.

On the other hand, in Comparative Example 7, since the coating area ratio is small, a sufficient leakage preventing effect cannot be obtained when the coating thickness is thin.
Further, Comparative Examples 8 to 9 have sufficient leakage prevention effect,
It is not suitable for practical use, because it causes discoloration of oil and smearing of the coating film.

Therefore, the nipple covering position by the unvulcanized rubber composition is a portion excluding the area portion of 15% from the tip of the nipple, with respect to the area of the joint portion of the hose and the nipple, and
The covered area is the area of the connecting part of the hose and nipple,
It can be seen that it is necessary to be 15 to 85%.

<Effects of the Invention> According to the present invention, even after use at high temperature, leakage of fluid such as gas, fuel and oil from the joint between the hose and the fitting does not occur, and even if it is used at high temperature for a long time, Since the performance is maintained, it is highly reliable and contributes to high performance resource saving.

Further, the conventional fittings can be used as they are, and in the case of cement-like coating, a thin film with high thickness accuracy can be formed, and cost increase is small and mass production is easy.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view of a typical hose used in the present invention. FIG. 2 is a cross-sectional view showing a connected state of the hose and the fitting of the present invention. Explanation of symbols 10 …… Hose, 20a …… Resin layer, 20b …… Inner layer, 30 …… Reinforcing layer, 40 …… Outer rubber layer, 50 …… Fitting fitting, 50a …… Socket, 50b …… Nipple, 60 …… Unvulcanized rubber composition, 70 …… Hose end, 80 …… Nipple tip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 58-177684 (JP, U) JP 53-13806 (JP, B2) JP 58-53235 (JP, B2) JP 53- 436898 (JP, B2) Japanese Patent Sho 58-24678 (JP, B2)

Claims (3)

(57) [Claims] 1. A method of connecting a hose having at least an innermost layer with a thermoplastic resin layer and a joint fitting thereof, wherein the joint between the innermost layer of the thermoplastic resin and the nipple of the joint fitting is chlorosulfonated polyethylene (CSM). , Chlorinated butyl rubber (Cl-IIR) and brominated butyl rubber (Br-IIR)
At least one unvulcanized rubber selected from the group consisting of:
A method for connecting a hose and a fitting, which comprises connecting the unvulcanized rubber composition containing the vulcanizing agent and an organic solvent and having a minimum viscosity of 45 to 120 at 125 ° C. by a Mooney viscometer. 2. The thermoplastic resin layer is a polyamide resin layer, the hose further has a chlorinated butyl rubber layer as an outer layer, has a low Freon gas permeability, and is used for refrigerant transportation. A method for connecting a hose and a fitting according to claim 1. 3. The area of the joint between the hose and the nipple, excluding the area of 15% from the tip of the nipple, with respect to the area of the joint between the hose and the nipple. The method for joining a hose and a fitting according to claim 1 or 2, wherein the hose is fitted so as to cover an area of 15 to 85%.