JPH0230858B2 - GASORINJUNKANYOKANSETSUZOKUYOGOMUHOOSU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber hose for connecting a gasoline circulation pipe, which is used for connecting an engine and a gasoline tank in the engine room of an automobile. Conventionally, rubber hoses 4 used for such purposes
As shown in FIG. 1, it is composed of a combination of three layers of materials: an inner tube rubber layer 1 having gas-resistant properties, a fiber reinforcing layer 2, and an outer tube rubber layer 3 having weather resistance. As shown in FIG. 2, both ends of the rubber hose 4 were fitted onto the outer periphery of the metal pipe 5 in a bent state at the connection part, and fixed with a fastening band 6. However, in recent years, the automobile industry has developed significantly, and in particular, due to the increase in pressure and temperature of fuel due to measures against car exhaust, the inside of the engine compartment can reach temperatures of over 100 degrees Celsius at the top and - at the bottom.
Automotive fuel system hoses have different characteristics compared to conventional ones, as the temperature changes over a very wide range of 40℃ or less, and gasoline circulates as oxidized gasoline (hereinafter referred to as sour gasoline) at high temperatures. Various performances under various severe conditions are required, and conventional rubber hoses having an inner tube rubber layer 1 made of a general-purpose polymer having gasoline resistance can no longer be used. Against this background, fluorocarbon rubber (hereinafter abbreviated as FKM) is the material that satisfies the above performance.
In fact, FKM has excellent durability and sour gasoline resistance. However, FKM has inferior occlusion resistance and is very expensive compared to acrylonitrile-butadiene rubber (hereinafter abbreviated as NBR) used as a hose material, so in practice it cannot be used inside the outer tube rubber layer. The inner tube rubber layer located in the
The development of a rubber hose with an inner layer made of a compound of However, the practical applicability of the above FKM is limited by the problem that the adhesion between FKM and NBR is poor, which causes separation between the two layers during use, resulting in the hose not functioning satisfactorily. . Therefore, in order to solve such problems,
Improvements in adhesion between FKM and NBR are being investigated. However, a formulation of NBR with excellent adhesion to FKM (using sulfur as a crosslinking agent)
If the
The tightening force of the tightening member (sleeve, etc.) applied to the outer surface of the hose at the seal part decreases, causing the tightening member to rotate or the hose to come off from the metal pipe, which may eventually lead to fuel leakage such as gasoline during use. This poses a serious practical problem in that the hose may not function properly as a hose. The present invention was invented based on the above circumstances, and it improves the setting property of the BNR compound without reducing the adhesion between the FKM compound and the NBR compound. The purpose is to provide a rubber hose for connecting pipes for gasoline circulation, and its gist is that the inner tube rubber layer located inside the outer tube rubber layer is replaced with an outer layer made of a compound of NBR. , FKM, and a quinone compound was blended with the NBR in combination with sulfur and an organic peroxide as a crosslinking agent to construct the hose. Hereinafter, the present invention will be explained in further detail. The inner tube rubber layer in the present invention has a multilayer structure consisting of an inner layer and an outer layer, and the inner layer is
It is composed of a blend of FKM such as vinylidene fluoride-propylene hexafluoride copolymer, vinylidene fluoride-propylene hexafluoride-ethylene tetrafluoride terpolymer, and the outer layer contains sulfur and organic fluoride as a crosslinking agent. It is composed of a mixture of NBR combined with an oxide and a quinone compound. The reason why the NBR composition, which is a feature of the present invention, has the above structure is that when only sulfur is used as a crosslinking agent, the adhesiveness with FKM is improved but the setting property is poor; We focused on the fact that when only an organic peroxide is used as an agent, the tendency is opposite to that of a sulfur vulcanization system. The vulcanization curve of the NBR formulation was developed using two-stage vulcanization, i.e., an initial sulfur vulcanization to ensure good adhesion with FKM, followed by an organic peroxide vulcanization to increase the crosslink density. This is because good settling properties can be ensured. What is important here is to incorporate the quinone compound into the above-mentioned combined vulcanization system. Such quinone compounds have the function of scavenging radicals generated by thermal decomposition of organic peroxides, and in the coexistence of sulfur, organic peroxides, and quinone compounds, sulfur vulcanization initially occurs. (during this time, organic peroxide vulcanization is suppressed by the quinone compound), and then, after the quinone compound is all consumed in reaction with the organic peroxide, organic peroxide vulcanization occurs. . The quinone compound in the present invention includes p
-benzoquinone, tolquinone, t-butyl-p-
Compounds such as benzoquinone and hydroquinone are used, and the amount of compounding is 1 equivalent of organic peroxide.
0.1 to 0.9 equivalents are used, preferably 0.3 to 0.7 equivalents. In addition, as the organic peroxide in the present invention,
Those commonly used in rubber such as dicumyl peroxide, 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,3-di(t-butylperoxyisopropyl)benzene. is used, and the blending amount is usually about 1 to 8 parts by weight per 100 parts by weight of NBR. In addition, the sulfur commonly used as a crosslinking agent for rubber is used, and the amount of sulfur is NBR100.
It is usually about 0.5 to 5 parts by weight. The NBR used in the present invention can have a wide range of combined acrylonitrile content, but it is preferably in the range of 28 to 46% by weight when used under severe conditions such as automotive fuel hoses. . However, since the setting property is improved compared to the conventional method, it becomes possible to apply NBR with a high bonded acrylonitrile content, which originally has poor setting property. Furthermore, in the present invention, metal oxides, epoxy resins, and silica fillers can be included in the NBR mixture as necessary to ensure better adhesion with FKM. As the metal oxide, MgO, PbO, Al ₂ O ₃ , etc. are used, but MgO is particularly preferred, and the amount to be mixed is determined.
1 to 10 parts by weight is used per 100 parts by weight of NBR. The epoxy resin includes thermoplastic resins having two or more epoxy groups in one molecule, but the type obtained by the reaction of bisphenol A and epichlorohydrin is preferred, and Epicote 828 (trade name; (manufactured by Ciel Chemical) is used, and the blending amount is 5 to 20 parts by weight per 100 parts by weight of NBR. As a silica filler, NIPSEAL VN-
Acidic silica such as 3 (trade name; manufactured by Nippon Silica Co., Ltd.) and Carplex 1120 (trade name; manufactured by Shionogi & Co., Ltd.)
Basic silica, such as those manufactured by NBR Co., Ltd., is used, but basic silica is preferred, and the amount used is 5 to 80 parts by weight per 100 parts by weight of NBR. In addition, in the present invention, in order to improve adhesiveness,
In addition, carboxylic acid 1,8-
Diazabicyclo[5,4,0]undecene-7 salt (hereinafter referred to as carboxylic acid DBU salt) can also be blended. Such carboxylic acid DBU salts include naphthoic acid, 2-hydroxy-naphthoic acid, sorbic acid,
DBU of carboxylic acids such as 2-ethylhexylic acid, gallic acid, P-hydroxy-benzoic acid, cinnamic acid, etc.
Salts are used, but among them, DBU salts of naphthoic acid and sorbic acid are particularly preferred, and the blending amount is
1 to 5 parts by weight is used per 100 parts by weight of NBR. Incidentally, from the viewpoint of processability, dispersibility, etc., it is better to blend such carboxylic acid DBU salt into NBR than to FKM, and it is also preferable to have an effect on adhesion. In the present invention, FKM includes known injection materials,
For example, crosslinking agents (organic peroxides, polyol compounds, dithiol compounds, amine compounds, etc.), crosslinking accelerators, stabilizers, colorants, plasticizers, reinforcing agents (carbon black, etc.), etc. are blended, and in NBR, Similarly, known crosslinking accelerators, crosslinking accelerators, stabilizers, plasticizers, reinforcing agents, etc. are blended. Figure 3 shows one example of application of the present invention, in which 1a is an inner layer made of a blend of FKM, 1b is an inner layer made of a blend of FKM;
indicates the outer layer made of an NBR compound, and the inner tube rubber layer has a double structure of 1a and 1b. 2 indicates a reinforcing layer similar to the conventional one, and 3 indicates an outer tube rubber layer. An example of the method for producing the rubber hose of the present invention is to simultaneously extrude the NBR compound kneaded using a cooling roll and the FKM compound obtained in the same manner using an extruder, or to extrude the same using two extruders. After extruding the outer layer (NBR compound) onto the inner layer (FKM compound layer) using a machine, a fiber reinforcement layer is formed on top of that, and then the outer tube rubber layer is extruded using an extruder to integrate and vulcanize. It makes it adhere. Vulcanization conditions include temperature 145~170℃, time 30~
90 minutes is commonly used. As explained above, according to the present invention, the adhesiveness between the FKM compound layer (inner layer) and the NBR compound layer (outer layer) constituting the inner tube rubber layer is not reduced, and the NBR compound layer can be easily bonded. This makes it possible to provide a rubber hose for connecting gasoline circulation pipes that has improved sealability and long-term sealing reliability, and the practical application range of FKM can be expanded. Hereinafter, the present invention will be explained in more detail with reference to Examples. The formulations constituting the FKM compound layer used in the following examples are as shown in Table 1, and the formulations constituting the NBR compound layer are as shown in Table 2. The test piece was prepared by laminating the FKM compound layer and the NBR compound layer into sheets of 2 mm each, stacking them together, vulcanizing them at 160°C for 45 minutes, and conducting the following adhesion test. Table 3 shows the test results. (1) Adhesion under normal conditions: According to GIS K6301 (2) Adhesion after immersion in gasoline: After immersion in regular gasoline at room temperature for 72 hours, according to JIS K6301. Regarding the setting property, a compression set test was conducted at 100°C for 72 hours using a compression set test piece (vulcanized at 160°C for 45 minutes) based on JIS K6300.
The results are also listed in Table-3. Furthermore, the above-mentioned FKM compound and NBR compound were coextruded as the inner and outer layers of the inner tube rubber layer, respectively, and a reinforcing layer made of braided polyester fibers was applied around the outer circumference of the inner tube rubber layer. A rubber hose was made by applying layers. The vulcanization conditions were leaded vulcanization at 160°C for 60 minutes. The thickness of each layer is 0.5 mm for the inner layer, 0.7 mm for the outer layer, and 1.2 mm for the outer tube rubber layer. The following performance tests were conducted on the rubber hose obtained as described above. Table-4
The test results are shown below. The numbers of the comparative examples and examples in Table 4 correspond to the numbers of the comparative examples and examples shown in Table 3 above. (1) Horse Sour Gasoline Circulation Test A model sour gasoline was prepared by dissolving 1 g of lauroyl peroxide in 100 ml of regular gasoline, and a circulation test at 40°C for 1000 hours was conducted. (Gasoline was replaced every 168 hours.) Thereafter, the adhesive strength between the inner and outer rubber layers of the inner tube of the hose was measured. (2) Hose sealability test: 10% caulking rate with tightening member (sleeve)
After heat aging the hose for a predetermined time (heat aging at 120°C) at (hose outer diameter reduction rate), water was sealed inside the hose, and the pressure was further increased with nitrogen gas, and the occurrence of liquid leakage was examined. As is clear from Tables 3 and 4, according to the present invention, the setting property of the NBR compound layer can be improved without reducing the adhesiveness between the FKM compound layer and the NBR compound layer. This was confirmed in hose performance tests, and we were able to provide a hose with long-term sealing reliability.

[Table] *1; Product name, manufactured by DuPont

【table】

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional hose, FIG. 2 is a vertical cross-sectional view showing how the hose is used, and FIG. 3 is a cross-sectional view of an embodiment of the hose of the present invention. 1... Inner tube rubber layer, 1a... Inner layer, 1b...
Outer layer, 2... Reinforcement layer, 3... Outer tube rubber layer, 4...
...Rubber hose.

Claims (1)

[Claims] 1 The inner tube rubber layer located inside the outer tube rubber layer,
It is composed of an outer layer made of a blend of acrylonitrile-butadiene rubber and an inner layer made of a blend of fluorine rubber. A rubber hose for connecting pipes for gasoline circulation, characterized by containing the following.