JPS5913419Y2 - Liquid fuel hose - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hose for liquid fuel such as gasoline or light oil, and aims to provide a hose with excellent oil resistance and fuel oil impermeability.

Hoses used in the fuel system of gasoline-powered vehicles are exposed to high temperatures in the engine room, so even if oil-resistant materials such as Nidonol rubber are used, they are highly permeable to gasoline.
The permeated gasoline enters the cabin, which not only causes discomfort to the occupants, but is also unfavorable for their health.

Therefore, there is an urgent need to develop a rubber elastic material that is impermeable to gasoline, but no suitable material has been discovered at present.
Various attempts have been made to form a layer impermeable to gasoline or the like within a rubber hose.

For example, there are those in which water, ethylene glycol, etc. are encapsulated as a liquid layer that is difficult for gasoline etc. to pass through, those in which a metal plate is encapsulated, and those in which hard rubber or hard synthetic rubber is partially used.

However, it is difficult to form a continuous layer in a rubber hose with these materials, or even if they are formed, the entire hose loses its flexibility and cannot function as a rubber elastic hose.

Moreover, the method of enclosing a metal plate or the like has the drawback that it requires sizing processing by compression molding, injection molding, etc., which does not improve productivity.

In addition, rubber hoses for city gas and propane gas have been proposed in which the rubber tube is covered with an outer tube made of synthetic resin such as vinyl, but the vinyl tube itself has a wall thickness of 1 mm or more. The purpose is to prevent rubber from deteriorating due to oxidation, and is not intended to prevent permeability of liquid fuel such as gasoline as in the present invention.

The present invention is a liquid fuel hose made by continuously forming a thin oil-impermeable or hardly oil-permeable synthetic resin layer on the outer periphery of an oil-resistant rubber hose, which has an extremely thin synthetic resin coating film with a thickness of 500μ or less By forming this on the surface of the rubber hose, it was possible to significantly reduce liquid fuel permeability without reducing the flexibility of the rubber hose.

The structure of the liquid fuel hose of the present invention will be specifically explained below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a is a partial vertical cross-sectional view of the hose, and b is a cross-sectional view thereof.

In the figure, 1 is a liquid fuel transfer path inside the hose, 2 is an oil-resistant rubber hose layer, and an almost uniform oil-impermeable resin coating 3 (hereinafter simply referred to as resin coating) is coated on the outer surface of this rubber hose layer. Formed by painting.

The rubber hose 2 is made of oil-resistant rubber, such as nitrile rubber NBR, nitrile rubber and polyvinyl chloride blend NBR-PVC, and epichlorohydrin rubber CHR.

The resin coating film 3 is formed by painting as described above.

The method is to remove the oil and fat bones adhering to the surface of the rubber hose 2 by washing with a solvent such as methyl ethyl ketone, apply a polyamide primer with a spray gun, and electrostatically adsorb low melting point nylon powder. '
C. for 10 to 15 minutes to form a thin film.

Or simply apply a synthetic resin liquid and dry it to form a thin film.

The thinner the resin coating film 3 is, the more preferable it is because it does not impair the flexibility of the rubber layer.Actually, a thickness of 50μ or less and about 10μ gives good results, but it is safe to use a thickness of 50 to 200μ.
For thick hoses such as filler hoses of 50 mmφ or more, it is possible to use up to about 500 μm.

As the oil-impermeable synthetic resin to be used, polyamide resins such as 6-nylon, 6-row nylon, 11-nylon, and 12-nylon, especially low melting point copolymer nylon, are undesirable resins in terms of processing and performance. In addition to polyester resins, poacetal resins, cellulose acetate, polyvinylidene fluoride, polyvinyl alcohol, and polyimide resins, thermosetting epoxy resins, unsaturated polyester resins, phenol resins, and the like can also be used.

The effect of thin film coating of these synthetic resins is not limited to the effect of preventing permeation of liquid oil, but also has a remarkable effect on preventing permeation of gasified fuel oil.

The oil permeation prevention effect of the resin coating film 3 specifically explained above is shown in an experimental apparatus as shown in FIG. 3, and the experimental apparatus is shown in FIG. 2.

In other words, aluminum cup 4 is filled with gasoline (toluene 50%).
, isooctane 50%) 5 was injected, and a low melting point nylon thin film with a thickness of 80μ obtained by electrostatic adsorption was formed on a NBR plate with a thickness of 2.1mm as a test piece 6. A simple NBR plate was used as sample X, and with these, an aluminum cup was covered, and gasoline was completely sealed with 72 annular jigs with an inner diameter of 60 mmφ and fixing screws 8, and the gasoline was left at a predetermined temperature. Gasoline amount (cc
) is calculated and the relationship with the number of days is plotted in Figure 3.

Sample X in the figure. The index of Y 20.40 is the measured temperature 20
The temperature is ±5°C and 140±2°C. ■ indicates the case of liquid contact (Fig. 2), and g indicates the case of gas contact (Fig. 2 is turned upside down).

From the results shown in FIG. 3, it is clear that the hose having the structure of the present invention has significantly reduced fuel oil permeability for both liquid and gas, and has excellent gasoline permeation prevention performance.

In addition, it has better flexibility and better band tightening properties than conventional products, and it also has excellent workability because continuous electrostatic adsorption and melting methods can be used during manufacturing.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the liquid fuel hose of the present invention.
is a vertical cross-sectional partial view of the hose, and b is a cross-sectional view thereof. FIG. 2 is a sectional view of the fuel permeability measuring device, and FIG. 3 is a graph showing the relationship between the amount of gasoline permeation and the number of days. 1...Liquid fuel transfer path, 2...Rubber hose layer, 3...
...Oil-impermeable synthetic resin coating film (resin coating film), 4...Aluminum cup, 5...Gasoline, 6...Test sheet,
X: NBR (2.1 mm), Y: Low melting point copolymerized nylon (80μ)-NBR (2.1 mm).

Claims (1)

[Scope of utility model registration request] A liquid fuel hose comprising an oil-resistant rubber hose 2 and an oil-impermeable synthetic resin coating 3 having a thickness of 10 to 500 μm formed on the outer periphery.