JP3139198B2 - 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 economy has been more strictly regulated since 1996, and there is a demand for weight reduction from the viewpoint of improving fuel economy. because of 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. But F
As for the alternative to KM, even if it has excellent gasoline permeability resistance, it has high rigidity, so it is inferior in flexibility, inferior in kink resistance (buckling resistance), and hard to insert into metal pipes. Inferior and poor 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, a hose for an automotive fuel pipe according to the present invention is a hose for an automotive fuel pipe having an inner layer and an outer layer formed on the outer periphery of the inner layer. The inner layer is formed by the following component (A), the outer layer is formed by a rubber elastic material, and the thickness of the inner layer is 1 with respect to the inner diameter of the hose.
/ 30 or more, and the thickness of the outer layer is set to 1/6 or more with the inner diameter of the hose being 1. (A) A polyamide resin elastomer containing the following (a) and (b) as main components. (A) At least one of an ethylene-propylene-diene rubber and a hydrogenated acrylonitrile-butadiene rubber. (B) Nylon 6.

[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, when an outer layer made of a rubber elastic material is formed on the outer periphery of an inner layer formed of a polyamide resin elastomer containing nylon 6 and a specific rubber material as a main component,
The inner layer formed of the above polyamide resin elastomer has excellent gasoline permeation resistance due to the properties of nylon 6, and since it is compounded with a specific rubber material, it has excellent flexibility and sealability. Further, by using a rubber elastic material for the outer layer, kink resistance is improved and assembling workability is also improved. Further, the present inventors have found that the flexibility of the entire hose is improved by forming the thickness of the inner layer relatively thinner than the inner diameter of the hose and forming the thickness of the outer layer thicker than that of the inner layer. did.

Next, the present invention will be described in detail.

[0008] The hose for an automotive fuel pipe according to the present invention has an inner layer formed of a polyamide resin elastomer (component A) containing a specific rubber material (a) and nylon 6 (b) as main components, and a rubber on the outer periphery of the inner layer. And an outer layer formed of an elastic material. In the present invention,
The above-mentioned main component is intended to include the case where only the main component is included.

The inner layer is obtained by using a polyamide resin elastomer (component A) containing a specific rubber material (a) and nylon 6 (b) as main components. Examples of the specific rubber material (a) include ethylene-propylene-diene rubber (EPDM) and hydrogenated acrylonitrile-butadiene rubber (hereinafter, referred to as “hydrogenated NBR”), and are used alone or in combination. 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. . As the hydrogenated NBR, generally used ones can be used, and usually, the amount of bound acrylonitrile is 25 to 55% by weight (hereinafter, “%”).
Abbreviated as), and 90 double bond portions.
% Or more is preferably used. Examples of the nylon 6 (b) include conventionally known nylons, which are generally obtained by ring-opening polymerization of ε-caprolactane. It is preferable that the mixing ratio of the specific rubber material (a) and the nylon 6 (b) is set at a ratio of a / b = 10/90 to 70/30 by weight. That is, the mixing ratio of nylon 6 is 3
If it is less than 0 (the rubber material exceeds 70), the flexibility, kink resistance, assembling workability and sealability are extremely excellent, but the gasoline permeability resistance is inferior, and the mixing ratio of nylon 6 exceeds 90 (the rubber material is (Less than 10), the gasoline permeability resistance is extremely excellent, but the flexibility, kink resistance, assembling workability and sealability tend to be inferior.

In the present invention, the rubber material (a) of EPDM and hydrogenated NBR and the nylon 6
When the compatibility of (b) is poor, the EPDM and the hydrogenated NBR to which maleic acid is added at a ratio not exceeding 10% (maleic acid-modified one) are used, so that both EPDM and hydrogenated NBR are compatible. The solubility can be improved effectively. As described above, it is preferable to use a rubber material to which maleic acid is added at a ratio of 10% or less.
If the content of maleic acid in the hydrogenated NBR exceeds 10%, a gel is generated at the time of extrusion molding, and molding may not be performed.

Further, in addition to the specific rubber material (a) and nylon 6 (b), a vulcanizing agent may be blended for vulcanizing the rubber material. Examples of the vulcanizing agent include sulfur, peroxide, phenol resin, quinoid, and polyamine. Further, a plasticizer can be blended. Examples of the plasticizer include n-benzenesulfonic acid amide. When the vulcanizing agent is compounded, the compounding ratio is preferably set to 0 to 5 parts by weight based on 100 parts by weight of the rubber material (hereinafter abbreviated as "part"). Further, the mixing ratio of the plasticizer is preferably set to a ratio of 0 to 20% in nylon 6.
That is, when the content of the plasticizer exceeds 20%, the plasticizer is extracted by gasoline flowing in the pipe, and the extract tends to clog the injectors and the like in the piping system.

In addition to the above-mentioned vulcanizing agents and plasticizers, various additives such as vulcanization accelerators, anti-aging agents, processing aids and the like can be appropriately compounded as required.

The outer layer is formed by using a rubber elastic material. As the rubber elastic material, CR, CSM, a mixture of NBR and PVC, CHC, ethylene-propylene-diene rubber (EPDM), chlorinated polyethylene rubber (CP
E), acrylic rubber (ACM) and the like.

The automotive fuel pipe hose of the present invention is manufactured, for example, as follows. That is, first, a rubber material (a), nylon 6 (b), and various additives are blended, heated and melted, and uniformly mixed to prepare a polyamide resin elastomer (component A) as an inner layer forming material. Then, the polyamide resin elastomer (component A) is extruded into a tubular shape by an extruder. Next, the outer peripheral surface of the polyamide resin elastomer tubular body produced by extrusion molding is treated with an adhesive.
Next, a rubber elastic material is extruded on the surface treated with the adhesive while the inside of the inner layer is pressurized with air to form an outer layer made of rubber. Then, by heating and vulcanizing at a predetermined temperature, the automotive fuel pipe hose 1 having a two-layer structure as shown in FIG. 1 is manufactured. In the figure, 2 is an inner layer made of a specific polyamide resin elastomer, and 3 is an outer layer made of a rubber elastic material.

In the automotive fuel pipe hose 1 thus obtained, assuming that the inner diameter of the hose is 1, the thickness of each layer is preferably set to 1/30 or more as a relative value. The thickness of the outer layer 3 is preferably set to 1/6 or more. Specifically, when the inner diameter of the hose 1 is 3.0 to 15.0 mm, the thickness of the inner layer 2 is 0.1 mm.
It is preferable to set the thickness of the outer layer 3 to 1.5 mm.
Is preferably set in the range of 1.5 to 4.0 mm. Particularly preferably, the thickness of the inner layer 2 is 0.3 to 0.1.
5 mm, and the thickness of the outer layer 3 is 2.7 to 2.9 mm.

Further, the automotive fuel pipe hoe according to the present invention is provided.
In the first, from a specific polyamide resin elastomer
Flexural modulus of the inner layer 2 of 1000 to 7000 kgf /
cm ^TwoIs preferably set in the range. Particularly preferred
Is 4000-5000kgf / cm^TwoIt is. Also go
The hardness of the outer layer 3 made of elastic material is 45 to 75 (Hs).
It is preferable to set, particularly preferably 60 to 70
(Hs). Set the characteristics of each layer as described above.
With kink resistance, flexibility, airtightness,
A hose excellent in (insertability into a pipe) etc. can be obtained.
Swell.

The automobile fuel pipe hose 1 having the two-layer structure in which the inner layer 2 and the outer layer 3 are formed as described above is used by being fitted to a metal pipe 4 as shown in FIG. 2, for example.

[0018]

As described above, the automotive fuel piping hose of the present invention has a rubber elastic material on the outer peripheral surface of the inner layer formed of nylon 6 and a polyamide resin elastomer (component A) containing a rubber material as a main component. It has a two-layer structure in which an outer layer is formed. Moreover, the thickness of the inner layer and the thickness of the outer layer are set to predetermined values based on the inner diameter of the hose. For this reason, the thickness of the inner layer is set to be thin, and the material for forming the inner layer has excellent flexibility while having excellent gasoline permeation resistance, and also has excellent kink resistance, airtightness, assembly workability and pressure resistance. I have. Therefore, the hose for automobile fuel piping of the present invention is most suitable 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, and has a very high use value.

Next, examples will be described together with comparative examples.

First, a polyamide resin elastomer was prepared prior to the examples. [Production of polyamide resin elastomer] Polyamide resin (PA), hydrogenated NBR and EPD shown in Table 1 below
M and various additives were blended at the ratios shown in the same table, and heated and melted to produce a polyamide resin elastomer. In Table 1 below, PA6 is nylon 6
It is.

[0021]

[Table 1]

[0022]

Examples 1 to 9 and Comparative Examples 1 to 3 Using the raw materials shown in Tables 2 to 4 below, hoses for automobile fuel piping were obtained according to the above-mentioned production method. In addition, the thickness and flexural modulus of the inner layer, the thickness and hardness (JIS hardness) of the outer layer, and the inner diameter of the hose are also shown in Tables 2 to 4 below. The vulcanization conditions are as follows:
Set at 150 ° C. for 35 minutes. The flexural modulus of the inner layer was measured as follows. That is, based on a three-point bending test method in a plastic bending test method, a predetermined size (length: 80 ± 5 mm, width: 10 ±
(0.5 mm, thickness: 4 ± 0.2 mm). Then, using the apparatus shown in FIG. 3, the test piece 7 was bridged over two support tables 6, and the pressure wedge 5 was lowered from the center at a constant speed (30 mm / min). The load-deflection curve at this time was recorded on a chart paper, and the bending elastic modulus was calculated by the following equation.

E = L ³ / (4 × bh ³ ) × F / Y The meaning of each symbol in the above formula is shown below. E: Flexural modulus (kgf / cm ² ) L: Distance between fulcrums (cm) b: Width of test piece (cm) h: Thickness of test piece (cm) F: Arbitrary part of the first straight line of load-deflection curve (Kgf) Y: Deflection at load F (cm)

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

Comparative Example 4 A single-layer automotive fuel pipe hose made of a polyamide resin containing a plasticizer was prepared.

[0028]

Comparative Example 5 An inner tubular body was extruded using NBR,
Next, a reinforcing yarn layer was formed on the outer periphery of the inner layer tubular body by braiding a polyester yarn. Then, an outer layer was extruded on the outer periphery of the reinforcing yarn layer using CR. Thus, a hose for a vehicle fuel pipe was manufactured.

The hoses for automobile fuel piping obtained as described above were measured and evaluated for gasoline permeation resistance, kink resistance, flexibility, airtightness, assembling workability, and pressure resistance. In addition, the flexural modulus of the inner layer of the automotive fuel pipe hose as an example was measured. Then, from the above measurement results, each hose was comprehensively evaluated in three steps. That is, ○ was excellent, △ was normal, and × was inferior. The results are shown in Tables 5 to 7 below. The evaluation of each of the above properties was measured according to the following method.

[Gasoline Permeation Resistance] As shown in FIG.
A sample (hose) 10 cut to a specified length (free length 500 mm) is supplied to two pipes 13 and 1 of a fuel tank 12.
4 and fixed by a clamp 15. Then, the fuel tank 12 is filled with a sample fuel (regular gasoline) 11 up to 85% of the tank capacity, and the fuel 11 is brought into contact with the entire surface of the sample 10 in a 40 ° C. constant temperature bath.
It was left for 8 hours. Then, after standing, the sample 10 was removed from the fuel tank 12, and the fuel tank 1 shown in FIG.
The two ends of the sample 10 were fitted into two pipes 17 and 18 formed on the upper surface of 6, and were fixed with the clamp 15. 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.

[0032] 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.
A loop was made using a sample (hose) 19m, and the intersection was held by hand, and the sample 19 was pulled in the direction of the arrow and held for 1 minute. After holding, the outer diameter D ₁ (m
m) was measured to determine the retention. 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 equation, 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.

Those kinked with R less than 70R are indicated by ○, those kinked with 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 the sample was subjected to the bending test method for plastics.
It was measured based on the point bending test method. That is, as shown in FIG. 7, the hose 21 is bridged between the two support bases 20 and the pressure wedge 22 is extended from the center of the hose 21 by 30 mm / m.
The sample was lowered at a speed of "in", and the relationship between the displacement and the load at this time was measured.

When the load at a displacement of 10 mm is 1.
Those with less than 5 kgf / cm ² are ○, 1.5-3.0 kg
Those with f / cm ² were indicated as Δ, and those with more than 3.0 kgf / cm ² were indicated as ×.

[Airtightness] As shown in FIG.
Both ends of a sample (hose) 23 mm were fixed to a pipe 25 of a 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.
A sample (hose) 26 of 0 mm was set upright, and a pipe 28 attached to a compression tester 27 was moved at a speed of 3 in the direction of the arrow.
It was inserted into the hose 26 at 0 mm / min. 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, 70kgf / min
The pressure at the time of rupture by applying a pressure at a pressure rise rate of cm ² was measured.

[0043] 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.

[0044]

[Table 5]

[0045]

[Table 6]

[0046]

[Table 7]

From the results of Tables 5 to 7, the product of the example is
It can be seen that while having excellent gasoline permeation resistance, it also has excellent kink resistance, flexibility, airtightness, workability in assembling, and pressure resistance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view showing an example of the configuration of a vehicle fuel pipe hose of the present invention.

FIG. 2 is an explanatory sectional view showing a usage state of the hose for automobile fuel piping of the present invention.

FIG. 3 is an explanatory view showing a method for measuring a bending elastic modulus of a hose inner layer portion.

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 diagram showing a method for measuring and evaluating gasoline permeation resistance of a hose for automobile fuel piping.

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

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

FIG. 8 is an explanatory diagram showing a method for measuring and evaluating the airtightness of a hose for an automobile fuel pipe.

FIG. 9 is an explanatory view showing a method for measuring and evaluating the workability of assembling a fuel hose for an automobile fuel pipe.

[Explanation of symbols]

 1 Hose for automotive fuel piping 2 Inner layer 3 Outer layer

Continuation of the front page (56) References WO 94/19638 (WO, A1) (58) Fields investigated (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 (3)

(57) [Claims] 1. An automotive fuel piping hose comprising an inner layer and an outer layer formed on the outer periphery of the inner layer, wherein the inner layer is formed by the following component (A), and the outer layer is formed of a rubber elastic material. Formed, and the thickness of the inner layer is set to a dimension of 1/30 or more with the inner diameter of the hose being 1;
The hose for an automobile fuel pipe, wherein the thickness of the outer layer is set to 1/6 or more with the inner diameter of the hose being 1. (A) A polyamide resin elastomer containing the following (a) and (b) as main components. (A) At least one of an ethylene-propylene-diene rubber and a hydrogenated acrylonitrile-butadiene rubber. (B) Nylon 6. 2. The automotive fuel piping hose according to claim 1, wherein the component (A) is modified with maleic acid. 3. The thickness of the inner layer is set to 1/30 to 1/4 with respect to the inner diameter of the hose, and the thickness of the outer layer is set to 1/2 to 1/6 with the inner diameter of the hose as 1. The hose for an automotive fuel pipe according to claim 1 or 2, which is set.