JPS6033662B2 - Rubber hose for gasoline circulation pipe connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rubber hose for connecting a gasoline circulation pipe, which is mainly used to connect a metal pipe to a metal pipe joint in the engine room of an automobile.

As shown in FIG. 1, a rubber hose 4 conventionally used for this purpose consists of an inner tube rubber layer 1 having gasoline resistance, a reinforcing layer 2 made of fibers, and an outer tube rubber layer 3 having weather resistance.
It is composed of a combination of layered materials, and as shown in Figure 2, both ends are connected to metal pipes 5 in a bent state at the connection part.
It was attached to the outer periphery of the body and fixed with a fastening band 6.

However, in recent years, the automobile industry has developed significantly, and in particular, due to the higher pressure and temperature of fuel due to car exhaust measures, the temperature inside the engine room can vary widely, from more than 100 qo at the top to less than -40 qo at the bottom. In addition, gasoline is oxidized at high temperatures and circulates as sour gasoline (hereinafter referred to as sour gasoline), so automotive fuel system hoses require performance under various harsh conditions compared to conventional hoses. As a result, 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, fluororubber (hereinafter abbreviated as FKM) is a material that satisfies the above performance.
KM has excellent heat resistance, sour gasoline resistance, etc.

However, FKM has poor cold resistance and is very expensive compared to acrylonitrile-butadiene rubber (hereinafter abbreviated as NBR) used as a hose material. The inner tube rubber layer located at
The development of a rubber hose with an inner layer made of a compound of However, what further limits the practical application range of FKM is that FKM does not have good adhesion to other rubber materials such as NBR by normal means, and during use. There was a problem in that peeling occurred and the hose no longer functioned adequately.

The present invention was invented based on the above facts, and provides a rubber hose for connecting a gasoline circulation pipe in which a FKM compound and a NBR compound are firmly bonded without intervening an intermediate layer. It is intended for the purpose of
The gist of this is that the inner tube rubber layer located inside the outer tube rubber layer is combined with an outer layer made of a compound of NBR and an FK
1,8-diazabicyclo[5,4,0]undecene-7 salt of carboxylic acid represented by the following general formula (hereinafter referred to as carboxylic acid DBU) The reason lies in the fact that it has a composition that combines salt and salt.

[R: Alkyl group, phenyl, naphthyl group, etc.] The present invention will be explained in further detail below. In the present invention, the carboxylic acid DBU salts represented by the above general formula that are incorporated into NBR and/or FKM include naphthoic acid, 2-hydroxynaphthoic acid, sorpic acid, 2-ethylhexylic acid, gallic acid, and P-hydroxybenzoic acid. DBU salts of carboxylic acids such as cinnamic acid are used, and among them, DBU salts of naphthoic acid and sorbic acid are particularly preferred.

The blending amount is 0.0% based on the weight part of NBR or FKMIO.
1 to 5 weight, preferably 0.5 to 3 weight. If the amount is too small, there will be no effect on adhesion, and if it is too large, the interlayer adhesion under normal conditions will be good, but the gasoline resistance will deteriorate. Further, from the viewpoint of processability, dispersibility, etc., it is better to blend the carboxylic acid DBU salt in NBR than in FKM, and the effect on adhesion is also preferable.

Although the mechanism of action of carboxylic acid DBU salt is not clear,
It is thought that this promotes co-crosslinking at the interface between NBR and FKM.

In the present invention, in order to further strengthen the adhesion between the inner layer (FKM compound) and the outer layer (NBR compound) of the inner tube rubber layer, metal is added to the NBR compound constituting the outer layer. It is also possible to contain at least one selected from oxides, silica fillers, and epoxy resins.

As the metal oxide, Mg0, P, Al203, etc. are used, but Mg0 is particularly preferable, and the blending amount is NBRIO.
1 to 3 parts by weight based on the weight of .

As the silica-based filler, acidic silica such as Nip Seal VN-3 (trade name; manufactured by Nippon Silica ■) and basic silica such as Carbrex 1120 (trade name; manufactured by Shionogi & Co., Ltd.) are used. Silica is preferred, and the amount is 5 to 8 parts by weight based on NBRIOO parts by weight. Epoxy resins include thermoplastic resins having two or more epoxy groups in one molecule, but a type obtained by the reaction of bisphenol A and epichlorohydrin is preferred, such as Epiquat 828 (trade name; (manufactured by Shell Chemical Co., Ltd.), etc., and the blending amount is 1 to 10 parts by weight based on the weight part of NBRIO.

Examples of the FKM used in the present invention include vinylidene fluoride-propylene hexafluoride copolymer, vinylidene fluoride-propylene hexafluoride-tetrafluoroethylene terpolymer, and the like.

As for NBR used in the present invention, an effect on adhesion can be found by blending carboxylic acid DBU salt, regardless of the bound acrylonitrile content, but when used under harsh conditions such as in automobile fuel hoses, , the content of bound acrylonitrile is preferably in the range of 28 to 4% by weight.

In the present invention, FKM may contain other known auxiliary materials depending on the purpose, such as crosslinking agents (peroxide compounds, polyol compounds, dithiol compounds, amine compounds, etc.), crosslinking accelerators, stabilizers, colorants, plasticizers, and reinforcement. There is no problem in blending agents (force-pump rack, etc.). Also, NB
Similarly, known crosslinking agents, crosslinking accelerators, crosslinking accelerators, stabilizers, plasticizers, fillers (carbon black, etc.) and the like can be blended in R.

FIG. 3 shows one example of application of the present invention, where la is an inner layer made of a FKM compound, lb is an outer layer made of an NBR compound, and the inner tube rubber layer is made of la and lb. Consists of double structure.

2 indicates a reinforcing layer similar to the conventional one, and 3 indicates an outer tube rubber layer.

In addition, as an example of the method for manufacturing the rubber hose of the present invention, the NBR compound kneaded with a cooling roll and the FKM compound obtained in the same manner are co-extruded in two layers using an extruder, or extrusion using two devices is performed. After extruding the outer layer (NBR compound) onto the inner layer (FKM compound layer) using a machine, a fiber reinforced 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°C, time 30-90°C.
minutes are commonly used.

As explained above, the present invention has an FKM compound layer and an NBR layer.
The problem of adhesion with the compound layer has been solved, and the practical application range of FKM can be expanded thereby, which is a great practical benefit.

The present invention will be specifically explained below with reference to Examples, in which a case where a carboxylic acid DBU salt is blended into an NBR mixture will be shown.

The compounding process for forming the FKM compound layer used in the following examples is as shown in Table 1 below. Table 1 [FKM combination prescription 1]
) (parts by weight) *1; Trade name, manufactured by DuPont. The formulation for forming the NBR compound layer is as shown in Table 2 below.

The test piece was made by rolling the FKM compound layer and the NBR compound layer into two sheets each, and stacking them together.
It was vulcanized at ℃×45 min and the following test was conducted.

Table 3 shows the test results. '1' Adhesion under normal conditions...
...According to JISK 6301 '2) Ganlin immersion bond adhesion...Regular gasoline at room temperature x7 or after immersion, according to JISK muscle 01.

Table 2 [NBR blend disposal] (parts by weight) *2; Bound acrylonitrile content 41% by weight (product name: DNIO1, manufactured by Nippon Zeon) *3; Bound acrylonitrile content 31% by weight (product name; DN202, Japan) (manufactured by Zeon ■) Table 3 <Adhesion test results> Furthermore, the previous bait K
The M compound and the NBR compound were co-extruded as the inner and outer layers of the inner tube rubber layer, respectively, and a reinforcing layer made of braided polyester fiber was applied to the outer periphery of the outer tube rubber layer. A rubber hose was manufactured by applying the following steps.

The vulcanization conditions were leaded vulcanization of 16,000×60 h. The thickness of each layer is 0.5 Yanagi for the inner layer, 0.7 Yanagi for the outer layer, and 1.2 Yanagi for the outer tube rubber layer. The following performance tests were conducted on the rubber hose obtained as described above. Table 4 shows the test results. 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. Hose Sour Gasoline Circulation Test One day of lauroyl peroxide and one day of regular gasoline
Create a model sour gasoline dissolved in '00' and
A circulation test between 0qo x 100 cycles was conducted.

(Gasoline was replaced every hour.) Thereafter, the adhesive force between the inner and outer rubber layers of the inner tube rubber layer of the hose was measured.

Table 1 4 Hose performance test results *;Material destruction (rubber breakage)

[Brief explanation of the drawing]

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, la... Inner layer, lb
...Outer layer, 2...Reinforcement layer, 3...
...Outer tube rubber layer, 4...Rubber hose. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. The inner tube rubber layer located inside the outer tube rubber layer is composed of an outer layer made of an acrylonitrile-butadiene rubber compound and an inner layer made of a fluoro rubber compound, and Acrylonitrile-butadiene rubber and/or fluoro rubber contains 1 and 8 carboxylic acids represented by the general formula below.
- A rubber hose for connecting a gasoline circulation pipe, characterized in that it is composed of a diazabicyclo[5.4.0]undecene-7 salt. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [R: alkyl group, phenyl group, naphthyl group, etc.] 2. Compounding at least one selected from metal oxides, silica fillers, and epoxy resins with acrylonitrile-butadiene rubber. A rubber hose for connecting a gasoline circulation pipe according to claim 1. 3. The rubber hose for connecting a gasoline circulation pipe according to claim 2, wherein the silica filler is a basic silica filler. 4 Carboxylic acid 1,8-diazabicyclo[5,4,0
] A rubber hose for connecting a gasoline circulation pipe according to claims 1 to 3, wherein 0.1 to 5 parts by weight of undecene-7 salt is blended with respect to 100 parts by weight of acrylonitrile-butadiene rubber or fluorine rubber. . 5 Carboxylic acid 1,8-diazabicyclo[5.4.0
The rubber hose for connecting a gasoline circulation pipe according to claims 1 to 4, wherein the carboxylic acid of the undecene-7 salt is either naphthoic acid or sorbic acid. 6. A rubber hose for connecting a gasoline circulation pipe according to claims 1 to 5, wherein the acrylonitrile-butadiene rubber has a bound acrylonitrile content of 28 to 46% by weight.