JPH05193053A - Rubber laminate for fuel - Google Patents

Abstract

PURPOSE:To improve the adhesion of the rubber layer of an inner tube to a fluororubber inside layer and satisfy various capacities as an oil-resistant hose by adding tetraalkylphosphonium benzothiazolium (TRP-BT) to NBR rubber. CONSTITUTION:A rubber laminate for fuel is obtained by providing a first layer composed of a fluororubber compsn. containing a binary or ternary copolymer composed of vinylidene fluoride as raw material rubber and the second layer being in contact with the first layer and composed of an NBR rubber compsn. containing NBR with acrylonitrile content of 20-60wt.% or hydrogenated NBR as a polymer component. At this time, tetraalkylphosphonium benzothiazolium (TRP-BT) represented by formula I is added to the NBR rubber. By adding TRP-BT to the NBR rubber of the second layer, the interlaminar bonding strength of the second and first layers is enhanced and tear strength is also enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a rubber laminate having a multi-layer structure such as a rubber hose for fuel and a diaphragm used in a fuel oil system of an automobile.

[0002]

2. Description of the Related Art In a fuel oil system of an automobile, a rubber laminate having a multi-layer structure such as a rubber hose for fuel and a diaphragm is known. Among them, the conventional NBR rubber innermost layer is hardened and deteriorated due to the oxidation of fuel oil due to the high temperature of the engine room and the high pressure circulation, and the conventional NBR rubber is regulated by the SHED regulation. It has been practiced to laminate and use fluororubber on the surface of the oil resistant layer that comes into contact with gasoline.

However, the NBR layer and the fluororubber layer are usually poor in adhesiveness, and there has been a problem of delamination during actual use and damage associated therewith. Although many proposals have been made to improve the adhesiveness, it is still hard to say that it is perfect. For example, JP-B-55-16830, JP-B-55-16831,
JP-B-55-2336, JP-A-55-51554, JP-A-54-158
No. 481, Japanese Patent Publication No. 57-49391, Japanese Patent Publication No. 59-35787, etc. are all delaminated even in pressure vulcanization by a molding press, and the adhesive strength is further reduced in hose products. , Was difficult to put into practical use.

In addition, JP-A-56-121762 and JP-A-61-14
0692, JP 61-244545, JP 62-46641, JP 62-46642, JP 61-16621, JP 61-1662
Proposals such as No. 2 suggest that at least one of the layers is a peroxide vulcanizate, and even if the interlayer adhesion is sufficient, in order to avoid vulcanization inhibition of oxygen and organic substances during vulcanization, the hose surface It requires a special measure such as coating with lead or resin, and as a result, it has the drawback of increasing costs.

[0005]

Therefore, the present invention does not have such drawbacks, is extremely excellent in the adhesiveness of the inner tube rubber layer to the fluororubber inner layer, is not peroxide vulcanized, and has a low cost. Therefore, the present invention aims to provide a rubber laminate for fuel which can satisfy various performances as an oil resistant hose.

[0006]

[Means for Solving the Problems] As a result of examining the above problems, a rubber laminate for fuel having the following structure was developed. That is, a first layer made of a fluororubber composition and NBR or hydrogenated NB having an acrylonitrile content of 20 to 60% by weight.
A first NBR rubber composition containing R as a polymer component
A laminate having a second layer in contact with a layer, said NBR
A rubber laminate for a fuel, characterized in that a tetraalkylphossonium benzothiazolium (abbreviated as TRP-BT) shown in Chemical Formula 2 below is added to the rubber.

The fluorine-based rubber composition used for the layered body of the first layer is, for example, a binary or ternary copolymer made of vinylidene fluoride, tetrafluoroethylene or hexafluoropropylene, specifically Specifically, polymer components such as vinylidene fluoride-hexafluoropropylene copolymer and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer are used as raw material rubber, carbon black, vulcanization system It is prepared by appropriately mixing auxiliary materials such as chemicals and metal oxides. Preferred vulcanizing agents are polyol vulcanizing agents such as hydroquinone and bisphenol A, and peroxide agents such as dicumyl peroxide and dialkyl peroxide.

On the other hand, the layered body of the second layer which is in contact with the fluorine-containing rubber composition layer of the first layer is composed of the NBR rubber composition according to the present invention. As the NBR polymer, NBR or hydrogenated NBR having an acrylonitrile content of 20 to 60% by weight is used.

This is because when the acrylonitrile content is less than 20% by weight, the volume change rate (swelling) due to fuel immersion is significant, which causes a problem in fuel oil resistance, and when the acrylonitrile content exceeds 60% by weight. This is because the oil resistance is improved, but the cold resistance is deteriorated and there is a problem in workability. Therefore, the rate of holding these ranges is necessary to obtain effective adhesive force with the fluororubber layer and the performance of the entire laminate, and in these relationships, 20 to 60% by weight.
It is desirable that the range is set to. From the same viewpoint, this is also applied to hydrogenated NBR, and in hydrogenated NBR obtained by hydrogenating NBR, by introducing a saturated bond into the NBR main chain by hydrogenation, it is possible to improve the oil resistance of NBR. Therefore, heat resistance, ozone resistance, chemical resistance and mechanical strength can be imparted, which is desirable for the constitution of the present invention.

Various compounding agents such as carbon black, fillers such as fillers, antioxidants, vulcanizing agents, vulcanization accelerators, etc. are added to the NBR polymer as in the conventional case.
A vulcanization aid is blended. Further, if necessary, a softening agent, a plasticizer, a processing aid, a stabilizer, a coloring agent and the like may be appropriately added. Here, the vulcanizing agent and the vulcanization accelerator are organic peroxides, or sulfur compounds, thiazoles, sulfenamides,
Sulfur-promoter combination system such as thiuram type, dithiocarbamate type, vulcanization system with accelerator can be used.
The sulfur-accelerator combination vulcanization system and the accelerator combination vulcanization system are more preferable than the organic peroxide vulcanization because they are less likely to be decomposed by steam vulcanization.

With respect to such NBR rubber composition, the following 2
The component is added as an essential component or a combination component to form the NBR rubber composition of the present invention. First, the addition amount of TRP-BT as an essential component added to the above NBR rubber compounding is 0.2 to 8 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of NBR rubber. The amount of TRP-BT added is
If the amount is less than 0.2 parts by weight, the adhesiveness will be insufficient, and the adhesiveness and tear strength will improve with the addition, but at the same time the Mooney scorch time will gradually decrease and the tensile strength, cold resistance, compression set, etc. will deteriorate. I will do it. If the addition amount is 8 parts by weight or more, scorch progresses and scorch burn occurs. This TRP-BT has the structure shown in Chemical Formula 2 below.

[Chemical 2]

Here, R is represented by an alkyl group (CnH2n + 1). Especially, n = 3-6 is used suitably for this invention.
If the number of n is less than 2, scorching of rubber is promoted and n
If the number is larger than that, the effect of improving adhesion will decrease, and
If the number is 7 or more, there may be a practical problem. Note that each R may have a different number of n.

If necessary, N- along with the TRP-BT
(Cyclohexylthio) phthalimide is used, and this N- (cyclohexylthio) phthalimide has the structure shown in Chemical formula 3 below, and the amount of addition is 0 to 8 parts by weight, preferably 0.5 to 100 parts by weight of NBR rubber. 5 parts by weight. N-
If (cyclohexylthio) phthalimide is not added, the adhesive strength is likely to decrease due to heat aging, and at the same time the Mooney scorch time becomes short, which is a problem in processing. As N- (cyclohexylthio) phthalimide is added, the tensile strength and compression set are slightly lowered, but the scorch resistance is improved. Then, the initial adhesive strength of the laminate is remarkably improved, and after heat aging, the interlayer peeling strength after immersion in warm fuel is sufficiently maintained. However, when the amount added exceeds 8 parts by weight, the degree of vulcanization gradually decreases, the physical properties deteriorate, and the processability also decreases.

[Chemical 3]

[0014]

By adding TRP-BT to the NBR rubber of the second layer, the interlayer adhesion between the second layer of the NBR rubber composition and the first layer of the fluorine-based rubber composition is significantly improved. Tear strength is improved.

When N- (cyclohexylthio) phthalimide is used in combination with TRP-BT, the interlayer adhesion becomes more complete and the interlaminar peel strength against heat deterioration is significantly improved, and the interlaminar peel strength is sufficient even when immersed in fuel oil. And the scorch time is properly maintained.

Further, the first of the above-mentioned fluororubber compositions is used.
1 and a second layer made of an NBR rubber composition containing the above-mentioned components are laminated to form an inner tube rubber layer, and a conventional reinforcing thread layer and an outer tube rubber layer are added to the fuel as illustrated in FIG. The rubber laminate for use has an effect of satisfying various properties such as weather resistance and gasoline resistance as an oil resistant hose. Further, sufficient fuel oil resistance can be obtained in other laminated body diaphragms, lining sheets and the like.

[0017]

EXAMPLES The present invention will be described in detail below based on examples. Examples 1 to 9 Comparative Examples 1 and 2 An oil resistant rubber hose having the structure shown in FIG. 1 was manufactured by the method described below. The unvulcanized fluororubber composition having the composition shown in Table 2 is the inner layer rubber inner layer 1 of the first layer, and the NBR rubber composition having the composition shown in Table 1 is the inner layer rubber outer layer 2 of the second layer. Thus, extrusion molding was performed by a double extruder. The inner rubber hose had an inner diameter of 7.5 mm and a wall thickness of 2.0 mm, of which the inner layer had a wall thickness of about 0.5 mm.

[Table 1]

[0018]

The inner tube rubber hose was braided with a reinforcing yarn layer 3 made of polyester fiber at a braiding angle of 52 °, and the epichlorohydrin rubber composition was extrusion-coated as an outer tube rubber layer 4 on the outer side thereof. A metal mandrel with an outer diameter of 7.5 mm was inserted into this unvulcanized rubber hose using compressed air. The reinforcing yarn layer 3 after the insertion had a substantially static angle. This was vulcanized by direct steam vulcanization at 8 kgf / cm ² for 12 minutes, then the metal mandrel was pulled out, washed and heat treated to obtain a desired oil resistant hose.

Product Peeling Test A sample of the reinforcing hose product obtained by the above-mentioned manufacturing method is cut into a length of 25 mm, and a radial cut is made along the axis to expose the inner layer 1 of the fluororubber inner tube. A test sample was prepared by peeling about 90 ° between the inner layer 1 and the second outer layer 2 of the inner tube made of the NBR rubber composition containing the above components. Then, this test sample was attached to a product peeling test jig in the state shown in FIG. 2, and a peeling test was conducted at 25 ° C. and a pulling speed of 50 mm / min. The test is untreated, immersed in fuel oil C (isooctane / toluene = 50 / 50vol%) after 40 ℃ × 48Hr, 100 ℃, 70 hours and 120 ℃,
Both heat treatments were performed for 70 hours, and the results are shown in Table 3.

From the results shown in Table 3, the effect of improving the initial peel strength by the interlayer adhesion and the interlayer peel strength by the warm fuel immersion of the fuel rubber laminate according to the present invention is clear.

[Table 3]

Examples 10 to 12 In the NBR formulation of Example 8 shown in Table 1, TBP-
Formulations were prepared in which the n number of the alkyl groups shown in the chemical formula 2 of BT was changed to those shown in Table 4 below. Similarly, a fluororubber compound was prepared according to Table 2.

A sheet of the NBR composition having the above composition
(Thickness 2.0 m / m) and a sheet of the fluororubber compound (thickness 0.8
(m / m) unvulcanized rubber is laminated in advance and set in a molding die (50 tons, transfer molding machine) with a gap of 2.0 m / m and vulcanized at 160 ° C for 15 minutes. It was By this vulcanization molding, a NBR sheet thickness of 1.5 m / m and a fluororubber sheet thickness of 0.5 m / m were prepared. This laminated sheet was cut into a shape of an aluminum cup 14 having an inner diameter D = 50 m / m and a flange of about 10 m / m on the periphery, and the fluororubber layer 10 was closed so as to be inside. Then, about 20 cc of gasoline 12 is filled inside, and it is sandwiched by the annular packing 13 corresponding to the flange portion, and the space between them is tightened with the screws equally divided in the circumferential direction.
As described above, the fluororubber / NBR laminate was constantly sealed so that the gasoline was in contact. The aluminum cup of each example thus formed was allowed to stand still in a warm air thermostat at 40 ° C. so that the laminate was on the lower side, and left at 40 ° C. × 70 hr. Then, the state of change in appearance when the laminated body including the fluororubber layer 10 and the NBR rubber layer 11 is removed from the aluminum cup is shown in Table 5.
Summarized in.

From the results shown in Table 5, the alkyl group (C of tetraalkylphossonium benzothiazolium (TRP-BT))
nH2n + 1) is within the range of n = 3-6, fluororubber and N
There is no problem in the adhesiveness of the laminate with BR rubber and the practical usability,
It can be seen that the product performance is also good.

[0025]

[0026]

According to the constitution of the present invention, the adhesion of the laminated body of the fluororubber and the NBR of the present invention is carried out by unvulcanizing the first and second layered bodies laminated as exemplified in the manufacturing method of the oil resistant rubber hose. The rubber layer shows excellent adhesive strength only by vulcanization without using an adhesive. The initial adhesive strength due to the interlayer adhesion of the fluororubber / NBR laminate was increased, the adhesive strength did not decrease even after fuel immersion or aging, the reliability was improved, and an inexpensive rubber laminate was obtained. Therefore, the rubber laminate for fuel according to the present invention includes a rubber hose for fuel or a diaphragm,
Even when the lining sheet for fuel oil storage is in actual use, the quality of the product is highly reliable, and it can be applied to products by laminating various fluororubber layers.
As a result, the improvement effect in terms of performance is enhanced, and excellent cost performance can be realized.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view of an oil resistant rubber hose.

FIG. 2 is a perspective view of a product peeling test jig.

FIG. 3 is a cross-sectional view showing a state of a gasoline resistance test.

[Explanation of symbols]

 1 Inner tube rubber inner layer 2 Inner tube rubber outer layer 3 Reinforcing yarn layer

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[Procedure amendment]

[Submission date] February 27, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Delete

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

[Document name] Statement

[0005]

Therefore, the present invention has been further improved so that the adhesion of the inner tube rubber layer to the inner layer of the fluorocarbon rubber is extremely excellent, the cost is low, and various performances as an oil resistant hose are obtained. It is intended to provide a rubber laminate for fuel which can satisfy the above requirements.

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Claims (2)

[Claims] 1. A first layer comprising a fluororubber composition,
A laminate having a second layer in contact with a first layer comprising an NBR having an acrylonitrile content of 20 to 60% by weight or an NBR rubber composition containing hydrogenated NBR as a polymer component,
A rubber laminate for fuel, characterized in that tetraalkylphossonium benzothiazolium (TRP-BT) represented by the following chemical formula 1 is added to the NBR rubber. [Chemical 1] 2. The rubber laminate for fuel according to claim 1, wherein N- (cyclohexylthio) phthalimide is added together with TRP-BT.