JPS5938888B2 - Improved fuel hose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improved high performance fuel hoses and methods of manufacturing the same.

In the automotive industry, there is a need for improved fuel hose performance to withstand highly aromatic fuels, sulfur-containing gasolines, fuel permeation losses, and more severe service conditions.

For example, conventional nitrile rubber fuel hose tubing filled with carbon black is limited to heat aging resistance of 70 hours at 100 degrees Celsius, and General Motors' new specifications call for even more stringent testing standards. According to the improved fuel hose of the present invention, the heat aging resistance is 7 at 125°C.
Extended to 20 hours, preferably 1000 hours, fuel extraction methanol insolubles are reduced and -40°C performance can be achieved initially and even after exposure to petroleum and fuels.

By using an acrylonitrile/butadiene bonded antioxidant nitrile rubber inner tube with a coating of compounded chlorosulfonated polyethylene, the above advantages can be retained while maintaining an optimal balance between fuel permeation losses and low temperature flexibility. The fuel hose of the present invention comprises at least one layer of a nitrile rubber fuel-resistant tube bound to an antioxidant, or a chlorosulfonated tube, with or without reinforcement wrapped in braid or spiral fabric or filament. Coated with a heat and ozone resistant exterior compound such as polyethylene or other materials.

Using an antioxidant-bound nitrile polymer containing 22-32%, preferably 28-30% acrylonitrile, -40°C flex performance can be achieved.

Antioxidant-bonded nitrile rubbers containing 32-43% acrylonitrile have excellent fuel permeation loss resistance, and those containing 34-38% acrylonitrile polymer have excellent permeation resistance and low temperature flex properties. Preferred for balancing and optimizing.

This antioxidant-bonded nitrile rubber that prevents decomposition by ozone is mainly formulated with an inorganic filler containing enough carbon black for the purpose of coloring, and has good heat resistance, low-temperature flexibility, and is free from fuel-extracted methanol-insoluble matter. Preference is given to those plasticized with plasticizers selected to contribute to the presence of plasticizers.

When adding a conventional antioxidant, choose one that is compatible with the antioxidant binding system. As the lubricant and processing aid, those that are less likely to insolubilize the fuel are preferred. Vulcanization accelerator and zinc oxide activator cure systems with no or very little free sulfur are preferred for long-term heat resistance. The term antioxidant-bonded nitrile rubber 1 is used to describe a known terpolymer obtained from butadiene, acrylonitrile and N(4-anilinophenyl)methacrylamide or acrylamide, and is manufactured by Chemigurn H
It is available as R-765 nitrile rubber.

Chlorosulfonated polyethylene is known and Hyp
It is available as alOn (registered trademark of DuPont).

For every 100 parts of chlorosulfonated polyethylene, about 25 to 125 parts of filler, 3 to 8 parts of magnesium oxide, 3 to 8 parts of hydrocarbon plasticizer, and 0.5 to 0.5 to sulfur-type accelerator are added.
The resulting blended chlorosulfonated polyethylene is useful as a coating for hoses. The nature of the invention can be more easily understood by reference to the following examples.

In the examples, parts and percentages are by weight unless otherwise specified. Examples: Typical examples of bonded antioxidant nitrile rubber compounded to make hoses by extrusion molding as tubes are as follows: 1.2 parts of sulfur-type rubber promoter, sulfenamide-type promoter per 100 parts of masterbatch. Typically, 1.2 parts of the curing agent and a small amount of a scorch inhibitor, such as dithiomorpholine, are mixed to form a curing agent mixture.

This curing agent mixture is fed into an extruder and extruded into a hand tube. This tube was then coated with a compounded chlorosulfonated polyethylene commercially available under the DuPont registered trademark HypaION to a thickness of 0.5 to 1 cm! Coat n. The coated tube is then cured at 163° C. for 25 minutes to yield an improved hose. This improved hose provides 125% less heat in a circulating air oven compared to conventional hoses with nitrile rubber tubes and chlorosulfonated polyethylene coatings.
It was found that the practical life at ℃ was improved. Also, according to this novel hose, anti-methanol extractive properties,
It was also found that the characteristic values at -40°C were improved. In another embodiment of the invention, the bonded antioxidant nitrile rubber extruded tube can be wrapped with a reinforcing member, such as a nylon or polyester fabric or filament, before being coated with the chlorosulfonated polyethylene coaching.

This reinforced hose is particularly desirable when a pressurized system is required. Although several exemplary embodiments and details have been shown to illustrate the invention, it will be apparent to those skilled in the art that various changes may be made without departing from the spirit or scope of the invention.

Claims (1)

[Scope of Claims] 1. An improved fuel hose comprising an inner layer made of at least one nitrile rubber bound to an antiozonant and an outer sheath made of chlorosulfonated polyethylene. 2. The improved fuel hose of claim 1, wherein the fuel hose contains a reinforcing member. 3. The improved fuel hose of claim 1, wherein the nitrile rubber contains butadiene and 22-43% acrylonitrile.