JP3166390B2 - Hose for automotive fuel piping - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automotive fuel piping hose used for low-pressure hoses such as an evaporative hose, a breather hose, and a fuel hose for connecting an automobile gasoline tank to an engine.

[0002]

2. Description of the Related Art A fuel pipe of an automobile generally comprises a metal pipe and a hose connecting the metal pipes. Examples of such a hose include an evaporative hose connecting the gasoline tank to the engine, a breather hose used for the air vent portion of the gasoline tank, and a low-pressure fuel hose connecting the engine to the gasoline tank. The hose includes, for example, an inner tube rubber layer made of acrylonitrile-butadiene rubber (NBR), a reinforcing yarn layer made of braided or spiral knitted polyester yarn around the inner tube rubber layer, and an outer periphery of the reinforcing yarn layer. And an outer tube rubber layer made of a rubber elastic material. As the rubber elastic material, in the case of a low-pressure fuel hose, chloroprene rubber (CR), epichlorohydrin rubber (CHC), chlorosulfonated polyethylene rubber (CSM), or the like is used. Further, as the evaporation hose and the breather hose, a mixture of CR, CHC, CSM, NBR and polyvinyl chloride (PVC) is used.

[0003]

As for these hoses, a phenomenon has occurred in which vaporized gasoline permeates through the hose and leaks to the outside. Recently, the number of automobiles has been particularly increasing, and the deterioration of the environment due to gasoline leaking from such hoses has become a major problem. Therefore, it has been enacted to regulate the amount of vaporized gasoline leaking from such automobiles. In particular, since 1994, in California, the United States, the amount of permeated unburned evaporated gasoline from evaporation hoses has been strictly regulated. That is, about 1/1 of the conventional gasoline permeation amount
It is regulated to 0 or less. In addition, the standard line for fuel efficiency is scheduled to be more strictly regulated from 1996, and a reduction in weight is demanded from the viewpoint of improving fuel efficiency. For these reasons, a hose using a fluorine resin (FKM) instead of NBR, which is a material for forming the inner tube rubber layer, has been proposed. The hose made of this FKM can suppress the permeation amount of vaporized gasoline, but the cost is high because the FKM is expensive. Therefore, those having excellent gasoline permeation resistance in place of the above-mentioned FKM are being studied. However, in place of FKM, even though it has excellent gasoline permeability resistance, it has poor rigidity due to high rigidity.
There are various problems such as inferior kink resistance (buckling resistance), inferior assembling workability that it is difficult to insert into a metal pipe, and inferior sealing performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a low-cost automobile fuel hose having excellent gasoline permeability, flexibility, kink resistance, assembling workability, and sealability. The purpose is to provide.

[0005]

In order to achieve the above object, an automotive fuel piping hose according to the present invention comprises an inner layer, an intermediate layer formed on the outer periphery of the inner layer, and an outer layer formed on the outer layer of the intermediate layer. An automotive fuel pipe hose having an outer layer, wherein the inner layer is formed of a polyamide resin,
The intermediate layer is formed of a polyamide resin elastomer containing the following (A) and (B) as main components, and the outer layer is formed of a rubber elastic material. (A) Hydrogenated acrylonitrile-butadiene rubber. (B) Polyamide resin.

[0006]

In other words, the present inventors have conducted a series of studies in order to obtain a hose for automobile fuel piping which is excellent not only in gasoline permeability but also in kink resistance, assembly workability and flexibility. As a result, a polyamide resin having excellent gasoline permeability is used as the material for forming the inner layer, a rubber elastic material having high kink resistance is used for the outer layer, and a gasoline-resistant material is used as a material for forming the intermediate layer formed between the two layers. The present inventors have found that the intended purpose can be achieved by using a specific polyamide resin elastomer having permeability and flexibility, and reached the present invention.

Next, the present invention will be described in detail.

The automotive fuel piping hose of the present invention comprises an inner layer made of a polyamide resin, an intermediate layer made of a specific polyamide resin elastomer on the outer periphery of the inner layer, and a rubber elastic material formed on the outer periphery of the intermediate layer. It has a three-layer structure of outer layers.

As a material for forming the inner layer, a polyamide resin having excellent gasoline permeation resistance is used. Examples of the polyamide resin include nylon 6, nylon 1
1, nylon 12, nylon 66 and the like.

As the intermediate layer forming material, a specific polyamide resin elastomer is used. Flexibility is imparted by using this specific polyamide resin elastomer. In addition, since the specific polyamide resin elastomer has the property of a conductive function, it can be prevented from being charged. The specific polyamide resin elastomer is water
Acrylonitrile-butadiene rubber (hereinafter referred to as “hydrogenated
( NBR )) The main component is (A) and a polyamide resin (B). As the polyamide resin,
Nylon 6, nylon 11, nylon 12, and the like . These may be used alone or together. Also,
In combination with the hydrogenated NBR, ethylene-propylene-die
A rubber component such as rubber (EPDM) may be used. The hydrogenated NBR is obtained by adding a hydrogen atom to a double bond portion in a molecule of acrylonitrile-butadiene rubber, and the flexibility of the polyamide resin can be improved by using the hydrogenated NBR. . This hydrogenated NB
As R, generally used ones can be used, and usually, the amount of bound acrylonitrile is 25 to 5
It is preferable to use about 5% by weight (hereinafter abbreviated as "%") of which about 90% or more of the double bond portion is hydrogenated. The mixing ratio of the rubber component (A) and the polyamide resin (B) is A / B in weight ratio.
= 10/90 to 70/30. That is, when the compounding ratio of the rubber component is less than 10 (the polyamide resin exceeds 90), the gasoline permeation resistance is good, but the flexibility is poor, and the compounding ratio of the rubber component is 70.
(Polyamide resin is less than 30), the flexibility is good, but the gasoline permeation resistance tends to be inferior.

[0011] In the above polyamide resin elastomer, a polyamide resin (B) and the upper Kisui added NB R (A)
If compatibility is poor, as the upper Kisui hydrogenated NBR, 10
%, Maleic acid is added (maleic acid-modified one) at a ratio not exceeding%, whereby the compatibility between the two can be effectively improved. in this way,
Preferably with 10% or less of the rubber material is maleic acid is added at a ratio of maleic acid contained in the hydrogenation NBR is cause by gel occurs during more than the extrusion molding of 10%, not be able to molding This is undesirable.

Further, in addition to the hydrogenated NBR (A) and the polyamide resin (B), a vulcanizing agent may be blended for vulcanizing the hydrogenated NBR (A). Examples of the vulcanizing agent include sulfur, peroxide, phenol resin, and quinoid. Further, a plasticizer can be blended. Examples of the plasticizer include benzenesulfonic acid amide. When the vulcanizing agent is blended, the blending ratio is preferably set to 0 to 5 parts with respect to 100 parts by weight of hydrogenated NBR (A) (hereinafter abbreviated as "part"). The mixing ratio of the plasticizer is preferably set to a ratio of 0 to 20% in the polyamide resin (B). That is, when the content of the plasticizer exceeds 20%, the plasticizer is extracted by gasoline flowing in the pipe,
This is because the extract tends to clog the injectors and the like in the piping system.

In addition to the above vulcanizing agents and plasticizers, various additives such as a vulcanization accelerator, an antioxidant, and a processing aid can be appropriately compounded as required.

Examples of the rubber elastic material which is a material for forming the outer layer formed on the outer periphery of the intermediate layer include NBR rubber, terpolymer of epichlorohydrin-ethylene oxide-allyl glycidyl ether (ECO), and chlorosulfonated polyethylene. Rubber (CSM), rubbery chlorinated polyethylene (CPE), acrylic rubber (ACM), chloroprene rubber (CR), EPDM, isobutylene-isoprene rubber (IIR), halogenated butyl rubber, and the like.

The automotive fuel pipe hose of the present invention is manufactured, for example, as follows. That is, first, an inner layer tubular body is extruded from a polyamide resin as a raw material onto a mandrel by an extrusion molding machine. Next, hydrogenated NBR
Then, a specific polyamide resin elastomer is produced by blending the polyamide resin and other additives at a predetermined ratio.
Using this specific polyamide resin elastomer, a specific polyamide resin elastomer is extruded on the outer peripheral surface of the inner layer tubular body to form an intermediate layer. Then, an outer layer is formed by extruding a rubber elastic material on the outer periphery of the intermediate layer, and then integrated by heat vulcanization to extract a mandrel, thereby manufacturing a three-layer automotive fuel pipe hose. The vulcanization conditions in this case are usually at a temperature of 150
１６０160 ° C., time 30３０60 minutes. Also,
A three-layer hose may be simultaneously extruded by an extruder.

FIG. 1 is a partially cutaway view of the hose for an automobile fuel pipe obtained as described above, and FIG. 2 is a sectional view thereof. In the figure, 1 is an inner layer made of a polyamide resin, 2 is an intermediate layer made of a specific polyamide resin elastomer, and 3 is an outer layer made of a rubber elastic material. In the hose for an automotive fuel pipe of the present invention, the thickness of each layer is set in the range of 1 to 10 with the thickness of the inner layer 1 as 1 based on the thickness of the inner layer 1. It is preferable that the thickness of the outer layer is set in a range of 1 to 35, where the thickness of the inner layer 1 is 1. As described above, by forming the inner layer 1, which is inferior in flexibility, to be thinner than the other layers (the intermediate layer 2 and the outer layer 3), excellent flexibility can be improved. Specifically, the inner layer 1 has a thickness of 0.1 to 0.1 mm.
It is preferable that the thickness is set within a range of 5 mm, the intermediate layer 2 is set within a range of 0.1 to 1.5 mm, and the outer layer 3 is set within a range of 1.0 to 3.8 mm. Particularly preferably, the inner layer 1 is 0.1
mm, the middle layer 2 is 0.3 mm, and the outer layer 3 is 2.8 mm.

[0017]

As described above, the automotive fuel piping hose according to the present invention has an inner layer made of a polyamide resin,
It has a three-layer structure in which an intermediate layer made of a specific polyamide resin elastomer is formed, and an outer layer made of a rubber elastic material is formed on the outer periphery of the intermediate layer. The specific polyamide resin elastomer is hydrogenated N
Because of the flexibility provided by the BR, the overall flexibility of the hose is improved, and the thickness of the polyamide resin in the inner layer can be reduced. An improvement in kink resistance can be realized. Further, since the specific polyamide resin elastomer has a conductive function, it is possible to prevent static electricity generated by friction between fuel such as gasoline and the inner wall of the hose. As a result, generation of spark is prevented. Therefore, ignition of the leaked gasoline based on the spark can be avoided, and the safety can be greatly improved.

Next, examples will be described together with comparative examples.

First, a polyamide resin elastomer was prepared prior to the examples.

[Preparation of polyamide resin elastomer] Polyamide resin (PA) and hydrogenated NB shown in Table 1 below
R, and further, various additives were blended in the proportions shown in the same table, and heated and melted to produce a polyamide resin elastomer.
In Table 1 below, PA6 is nylon 6, P6
A11 is nylon 11.

[0021]

[Table 1]

[0022]

Examples 1 to 4 Using the polyamide resin elastomers shown in Table 1 above and the raw materials shown in Table 2 below, hoses for automobile fuel piping having a three-layer structure shown in FIG. The flexural modulus of the inner layer and the intermediate layer and the hardness of the outer layer were measured and shown in the same table. The bending elastic modulus was measured based on a three-point bending test method in a plastic bending test method. The hardness was measured according to JIS standards.

[0023]

[Table 2]

[0024]

Comparative Example 1 Using a mixture of NBR and PVC (mixing ratio (weight ratio): NBR / PVC = 70/30), a single-layer automotive fuel pipe hose was produced by an extruder.

[0025]

Comparative Example 2 A tubular inner layer made of a polyamide resin was formed by an extruder, and an outer layer made of a rubber elastic material was formed on the tubular inner layer to produce a two-layered automotive fuel hose.

With respect to the hoses for automobile fuel pipes of Examples 1 to 4 and Comparative Examples 1 and 2 thus obtained, gasoline permeability, kink resistance, flexibility, airtightness, assembly workability, pressure resistance The properties were measured and evaluated. Then, from the above measurement results, each hose was comprehensively evaluated in three steps. That is,
○ indicates excellent, △ indicates normal, and × indicates inferior. The results are shown in Table 3 below. The evaluation of each of the above properties was measured according to the following method.

[Gasoline Permeation Resistance] As shown in FIG. 3, a sample (hose) 10 cut to a specified length (free length 500 mm) is fitted into two pipes 13 and 14 of a fuel tank 12 and clamped by a clamp 15. Fixed. Next, the fuel tank 12 has a capacity of 8 tanks.
The sample fuel (regular gasoline) 11 is filled up to 5%, and the fuel
It was left for 168 hours in a thermostat at ℃. Then, after standing, the sample 10 was removed from the fuel tank 12 and
The two ends of the sample 10 are fitted into two pipes 17 and 18 formed on the upper surface of the fuel tank 16 shown in FIG.
Fixed at 5. Next, the fuel tank 16 was filled with about 100 cc of new prescribed gasoline 11, and the inside of the sample 10 was made into a gasoline vapor shape. Then, in this state, the entire weight was measured in a constant temperature bath at 40 ° C. every 24 hours for 3 days.
Then, the gasoline permeation amount was calculated by the following equation.

Θ = [Wn−W (n−1)] / S In the above equation, Θ represents the amount of permeation per day (g / m ² / da).
y), S is the area (m ² ) of the outer surface of the sample 500 mm, W
n is the mass (g) of the sample set state after n days, and n is an integer of 0 to 3.

[0029] And, those of less than 100g / m ² / day is one of ^{○, 100~300g / m 2 / day} △,
Those exceeding 300 g / m ² / day were indicated as x.

[Kink Resistance] As shown in FIG. 5, a loop is formed using a sample (hose) 19 having a length of 1 m, the crossing portion is held by hand, and the sample 19 is pulled in the direction of the arrow for one minute. Held. After the holding, the outer diameter D ₁ (mm) of the sample 19 in the R portion was measured, and the holding ratio was obtained. Next, the diameter of the ring at the R portion where the kink was obtained by further reducing the diameter of the ring was determined. The retention was calculated by the following equation.

Retention (%) = (D ₁ / D) × 100 In the above formula, D is the outer diameter (m) of the initial sample (hose).
m). However, both D ₁ and D are samples (hose)
It is the minor diameter of the outer diameter.

Then, those kinked with R less than 70R are indicated by ○, those kinked by R in the range of 70R to 100R are indicated by Δ, and those kinked by R larger than 100R are indicated by ×.

[Flexibility] A sample (hose) having a length of 150 mm was prepared and measured based on a three-point bending test method in a plastic bending test method. That is, as shown in FIG.
The pressure wedge 22 was lowered from the center of the hose 21 at a speed of 30 mm / min, and the relationship between the displacement and the load at this time was measured.

The load at a displacement of 10 mm is 15
Those having a weight of less than kgf / cm ² are ○, 15 to 35 kgf / c
△ for m ² , × for 35 kgf / cm ²
Displayed as

[Airtightness] As shown in FIG. 7, a 300 mm long sample (hose) 2
3 were attached and fixed to the pipe portion 25 of the fixing jig 24. Then, air (or an inert gas) was sent from the direction of the arrow to the hole at the end of the fixing jig 24 to fill the inside of the hose 23 with a specified pressure and dipped in the water tank. After a lapse of a prescribed time, the presence or absence of leakage of the pressurized gas was examined.

The specified pressure is 10 kgf / cm ²
Higher ones ○, of those ^{2~10kgf / cm 2 △, 2kgf /} cm 2 less than what is displayed as ×.

[Assembling workability] As shown in FIG. 8, a sample (hose) 26 having a length of 50 mm was used.
Is set upright, and the pipe 28 attached to the compression tester 27 is connected to the hose 26 at a speed of 30 mm / min in the direction of the arrow.
Inserted in. The maximum load during the insertion was measured.

Those having a weight of less than 15 kgf are rated as ○, 15
~ 30kgf is △, and over 30kgf is ×
Displayed as

[Pressure Resistance] A hose having a length of 300 mm was attached to a burst tester, and a sample (hose) was filled with a pressurized liquid (water or oil). Then, the pressure was measured at a pressure of 70 kgf / cm ² per minute and the pressure at the time of rupture was measured.

[0040] and, more than 50kgf / cm ² is ○, those of 10~50kgf / cm ² △, 10kg
Those with less than f / cm ² were indicated as x.

[Ignition Resistance] A charge of 30 to 50 kV was applied to each hose, a metal needle was brought close to the hose, and a spark phenomenon was confirmed. When no spark was generated, it was evaluated as ○, and when spark was generated, it was evaluated as x.

[0042]

[Table 3]

From the results shown in Table 3 above, the comparative example is poor in either gasoline permeation resistance or kink resistance. On the other hand, it can be seen that the products of Examples have excellent kink resistance, flexibility, airtightness, workability in assembling, pressure resistance and ignition resistance, while having gasoline permeability resistance.

[Brief description of the drawings]

FIG. 1 is a cutaway view showing a configuration of an embodiment of a vehicle fuel pipe hose of the present invention.

FIG. 2 is a longitudinal sectional view of the hose.

FIG. 3 is an explanatory diagram showing a method for measuring and evaluating gasoline permeation resistance of a hose for an automobile fuel pipe.

FIG. 4 is an explanatory view showing a method for measuring and evaluating gasoline permeation resistance of a hose for automobile fuel piping.

FIG. 5 is an explanatory view showing a method for measuring and evaluating kink resistance of a hose for an automobile fuel pipe.

FIG. 6 is an explanatory view showing a method for measuring and evaluating the flexibility of a hose for an automobile fuel pipe.

FIG. 7 is an explanatory diagram showing a method for measuring and evaluating the airtightness of a hose for an automobile fuel pipe.

FIG. 8 is an explanatory view showing a method for measuring and evaluating the workability of assembling a hose for an automobile fuel pipe.

[Explanation of symbols]

 1 inner layer 2 middle layer 3 outer layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-192189 (JP, A) JP-A-4-145284 (JP, A) JP-A-6-238827 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 F16L 9/00-9/22 F16L 11/00-11/24 WPI / L (QUESTEL) EPAT (QUESTEL)

Claims (2)

(57) [Claims] An automotive fuel piping hose comprising: an inner layer; an intermediate layer formed on the outer periphery of the inner layer; and an outer layer formed on the outer periphery of the intermediate layer, wherein the inner layer is formed of a polyamide resin. And the above intermediate layer has the following (A)
And (B) a polyamide resin elastomer, wherein the outer layer is formed of a rubber elastic material. (A) Hydrogenated acrylonitrile-butadiene rubber. (B) Polyamide resin. 2. The thickness of each layer is based on the inner layer, the thickness of the intermediate layer is set in the range of 1 to 10 with the thickness of the inner layer being 1, and the thickness of the outer layer is 1 to 35 with the thickness of the inner layer being 1. The automotive fuel pipe hose according to claim 1, wherein the hose is set within the range.