JPH0138996B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a rubber hose for connecting a gasoline circulation pipe, which is used for connecting a metal pipe to a metal pipe connection mainly in the engine room of an automobile. (Prior art) In recent years, the automobile industry has developed significantly, especially due to the increase in pressure and temperature of fuel due to measures against vehicle exhaust gas.
The inside of the engine room is over 100℃ above and -40℃ below.
Fuel hoses for automobiles have a higher level of heat resistance than before, as the temperature changes over a very wide range, and gasoline circulates as oxidized gasoline (hereinafter referred to as sour gasoline) at high temperatures. In addition to requiring a balance of cold resistance and cold resistance, a higher level of resistance to sour gasoline is also required. As a result, conventional rubber hoses with inner tube rubber layers made of general-purpose rubber compounds such as unsaturated nitrile-conjugated diene copolymer rubber (hereinafter referred to as NBR) can no longer be used, and hoses with excellent heat resistance and sour gasoline resistance can no longer be used. Plain rubber (hereinafter referred to as FKM) has come to be considered as a material for the inner tube rubber layer. However, although FKM has the above-mentioned excellent properties, it has poor cold resistance and is also very expensive compared to general-purpose rubber such as NBR. rubber layer,
A structure composed of an outer layer made of a compound such as NBR and an inner layer made of a compound FKM is known, and some of it is also in practical use. (Problems to be solved by the invention) However, in such a rubber hose,
Good adhesion of FKM to other rubber materials such as NBR cannot be obtained by normal means, and if sufficient measures are not taken to prevent this, it may peel off during use and lose its function as a hose. There is a problem of insufficient performance, and cost reduction has also become an important issue in the industry. The present invention was invented based on these circumstances, and has not only a good balance between heat resistance and cold resistance, but also a high level of sour gasoline resistance, and there is no fear of adhesive peeling. , also in terms of cost
The purpose of this invention is to provide a rubber hose for connecting gasoline circulation pipes that is cheaper than when FKM is used. (Means for Solving the Problems) In order to achieve the above object, the present invention combines an inner tube rubber layer located inside an outer tube rubber layer with an outer layer made of a blend of NBR and a conjugated diene unit portion. The first gist is a rubber hose composed of an inner layer made of a mixture of hydrogenated NBR (hereinafter referred to as H-NBR), which is partially or completely hydrogenated with silica. The inner tube rubber layer is made of an outer layer made of NBR, and a vinyl chloride resin (hereinafter referred to as PVC) is blended with H-NBR.
A second rubber hose is further provided with an inner layer made of a compound mixed with silica.
The summary is as follows. H-NBR is NBR produced by emulsion polymerization or solution polymerization, and a part or all of the conjugated diene units are hydrogenated using a normal method.
Usually, those having a hydrogenation rate of 50% or more, preferably 80% or more are used. The upper limit of the hydrogenation rate may be 100%, but in this case peroxide vulcanization is applied,
When performing sulfur vulcanization, the hydrogenation rate should be 98% or less. The amount of bonded unsaturated nitrile (ACN) in H-NBR is usually 36 to 50 wt% from the viewpoint of fuel oil resistance or compatibility with PVC, and the blending ratio with PVC is H-NBR/PVC = 85~40/15~60wt
% ratio. Blending silica greatly contributes to improving sour gasoline resistance, and the amount of silica mixed is H-NBR or H-NBR.
-NBR/PVC 100 parts by weight (hereinafter referred to as "parts")
10 parts or more, preferably 20 to 80 parts.
Further, as for the type of silica, both acidic and basic silica can be used, but basic silica has a greater effect of improving sour gasoline resistance. The ACN amount of NBR that makes up the outer layer of the inner tube rubber layer is usually H-NBR (ACN amount 36 to 50 wt%) used for the inner layer because it does not come into direct contact with fuel oil such as gasoline.
Those with low nitrile content compared to, e.g. 28~
36wt% is used. The structure of the inner tube rubber layer is divided into two layers: an inner layer and an outer layer having such an amount of ACN.
With a heavy structure, the inner layer maintains fuel oil resistance, and the outer layer prevents deterioration of the settling property. Various commonly used auxiliary materials such as reinforcing agents (carbon black, etc.), plasticizers, stabilizers, anti-aging agents, etc. are appropriately blended into the above H-NBR or H-NBR/PVC mixture, and further An ionic or peroxide vulcanizing agent is appropriately blended. Regarding heat resistance, it has been improved over conventional NBR by using H-NBR and adding silica.
Cold resistance is improved over conventional NBR by using H-NBR and by using a lower amount of ACN in the outer layer than in the inner layer. Furthermore, since the inner layer and outer layer of the inner tube rubber layer are made of the same type of rubber, they have excellent vulcanization adhesion. (Example) The present invention will be explained in detail below. FIG. 1 is a sectional view showing the structure of the rubber hose of the present invention, in which a fiber braided reinforcing layer 2 is laminated on the outer surface of an inner tube rubber layer 1, and an outer tube rubber layer 3 made of rubber with excellent weather resistance is further laminated on the outer surface of the fiber braid reinforcing layer 2. The rubber hose 4 is constructed by using the rubber hose 4. Moreover, the inner tube rubber layer 1 further consists of an inner layer 1a and an outer layer 1b. Then, as shown in FIG. 2, both ends of the rubber hose 4 are fitted onto the outer periphery of the metal pipe 5 and fixedly attached with a fastening band 6 for use. Next, the present invention will be specifically explained based on Examples. Rubber hoses of Examples and Comparative Examples as shown in Table 1 were manufactured. In each example, the thickness of the inner tube rubber layer is 2
mm (However, in the case of double structure, the inner layer,
Both outer layers were each 1.0 mm. ), the material of the outer tube rubber layer was a compound of epichlorohydrin rubber, its wall thickness was 1.2 mm, and a braided reinforcing layer made of polyester fiber was provided between the inner tube rubber layer and the outer tube rubber layer. The results of evaluating each material property and hose performance of these rubber hoses are also listed in Table-1. The composition of each material used for the inner tube rubber layer is shown in Table 2. In addition, the evaluation method for material properties and hose performance is as follows. (Method for evaluating material properties) (1) Heat aging resistance Compliant with JISK6301. The data shows the rate of change after heat aging at 100°C for 72 hours. (2) Settling property Compliant with JISK6301. Compression set due to heat aging at 100°C for 72 hours was measured. (3) Cold resistance JISK6301 (impact embrittlement test) compliant. (4) Sour gasoline resistance Add 1g of benzoyl peroxide to the vulcanization compound.
and 100 ml of gasoline (warmed to 60°C).
After 48 hours of immersion, the blend was taken out and immersed again in a fresh gasoline mixture having the above composition under the same conditions, then taken out and the elongation was measured. The data indicate the elongation value at which the crack begins. (5) Adhesion Adhesion under normal conditions and after immersion in gasoline (regular gasoline room temperature x 72 hours immersion)
Compliant with JISK6301. (Hose performance evaluation method) (6) Sealing performance A connecting pipe was connected to the end of the rubber hose, and after tightening the rubber hose at a caulking rate of 20%, it was heat aged at 120°C for 72 hours. Thereafter, the assembled product (one end sealed) was immersed in water, nitrogen gas (pressure 20 kg/cm ² ) was blown from the other end, and the presence or absence of air bubbles from the connection between the rubber hose and the connecting pipe was examined. . (7) Sour gasoline resistance Benzoyl peroxide 1 in the rubber hose
Model sour gasoline with a concentration of 100ml of regular gasoline and 100ml of regular gasoline was filled in, and the rubber hose was repeatedly degraded through a 48-hour cycle at 60°C (liquid exchanged every 48 hours), and then the rubber hose was bent 180 degrees and cut open, causing cracks on the inner surface. The time (number of cycles) was investigated. In addition, as for the data, the life of Comparative Example 2 is 1
The relative lifespan ratio is shown. (8) Resistance to gasoline impermeability Regular gasoline or 20% methanol mixed gasoline was filled in a rubber hose, left at 40°C, and the amount of gasoline volatilized from the hose was measured from the weight loss after a certain period of time. (9) Cost The total cost as a rubber hose is shown as a relative cost ratio with Comparative Example 2 set at 1. As is clear from Table 1, Comparative Example 1 is inferior in cost and adhesion to the inner and outer layers, Comparative Examples 2 and 3 are inferior in sour gasoline resistance and heat resistance, Comparative Example 4,
No. 5 has poor sour gasoline resistance, whereas all examples have a good balance between heat resistance and cold resistance, as well as a higher level of sour gasoline resistance, and are free from adhesive peeling. It can be seen that a rubber hose that is cheaper than using FKM can be obtained in terms of cost. (Effects of the Invention) As explained in detail above, the present invention not only has a good balance between heat resistance and cold resistance, but also has a high level of sour gasoline resistance, has no fear of adhesive peeling, and is inexpensive. In general, a rubber hose for connecting gasoline circulation pipes can be obtained that is cheaper than when FKM is used.

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【table】 [Brief explanation of drawings]

FIG. 1 is a cross-sectional view illustrating the structure of the rubber hose of the present invention, and FIG. 2 is a cross-sectional view showing how the rubber hose is used. 1... Inner tube rubber layer, 1a... Inner layer, 1b...
Outer layer, 2... Reinforcement layer, 3... Outer tube rubber layer, 4...
...Rubber hose, 5...Metal pipe, 6...Tightening band.

Claims (1)

[Claims] 1. An inner tube rubber layer located inside the outer tube rubber layer,
An outer layer consisting of a blend of unsaturated nitrile-conjugated diene copolymer rubber, and a blend of hydrogenated unsaturated nitrile-conjugated diene copolymer rubber in which some or all of the conjugated diene units are hydrogenated and silica mixed therein. A rubber hose for connecting a gasoline circulation pipe, characterized by comprising an inner layer consisting of: 2. The inner tube rubber layer located inside the outer tube rubber layer,
The outer layer is made of a blend of unsaturated nitrile-conjugated diene copolymer rubber, and the vinyl chloride resin is blended with the hydrogenated unsaturated nitrile-conjugated diene copolymer rubber in which some or all of the conjugated diene units are hydrogenated. 1. A rubber hose for connecting a gasoline circulation pipe, characterized in that the inner layer is made of a mixture of silica and silica.