JPS63218348A - Rubber hose - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to rubber hoses, particularly rubber hoses such as fuel rubber hoses used for connecting metal pipes in the engine room of automobiles.

[Conventional technology]

As shown in Fig. 2, fuel rubber hoses have conventionally been made of a three-layer material consisting of an inner tube rubber layer 1 with gasoline resistance, a reinforcing layer 2 of fibers, and an outer tube rubber layer 3 with weather resistance. A combination of pipes 4 is used, and as shown in FIG. 3, both ends thereof are fitted onto the outer periphery of a metal pipe 5 and fixed with a fastening band 6 for installation. However, in recent years, the automobile industry has developed significantly.
In particular, due to the high pressure and high temperature of fuel due to car exhaust measures, the temperature inside the engine room ranges from over 100°C to -40°C.
It is subject to a wide range of temperature changes, down to low temperatures. In addition, automobile fuel rubber hoses are subject to various harsher conditions than conventional ones, such as when gasoline is oxidized and becomes sour gasoline (gasoline is oxidized at high temperatures and contains peroxide) and circulated. The reality is that various performances are required, and it is no longer possible to use conventional rubber hoses with an inner tube rubber layer made of a general-purpose polymer having gasoline resistance.

In addition, gasoline is a finite resource and is expected to be depleted in the future.To deal with this, it is possible to mix alcohol into gasoline and use it as fuel. It is also necessary to provide an inner tube rubber layer that has durability against. From this point of view, a material that satisfies the above performance is fluororubber (hereinafter abbreviated as rFKMJ), and this FKM has excellent heat resistance, sour gasoline resistance, and the like. However, on the other hand, it has poor low temperature characteristics (and is expensive).

For this reason, the inner tube rubber layer located inside the outer tube rubber layer is made into two layers, and the inner layer of the 2N layer is made of the above-mentioned FKM, and the outer layer is made of hydrin rubber or acrylonitrile-butadiene rubber (which has good low temperature characteristics). (hereinafter abbreviated as rNBRJ) (a material with a low nitrile content and good low-temperature properties), but this is still not satisfactory in terms of cost and the like.

[Problem that the invention seeks to solve]

On the other hand, a composite (blend) polymer of acrylic rubber and fluororesin has been developed as a material that has properties similar to the above-mentioned FKM in sour gasoline resistance, etc., and is considerably cheaper than FKM. However, since this blend polymer is a blend, it has a high hardness after vulcanization, and when this blend polymer is used, a problem arises in flexibility as a hose. Therefore, it is inexpensive and has all the characteristics required for fuel rubber hoses.
Moreover, it is desired to provide a rubber hose that has excellent low-temperature properties.

This invention was made in view of the above circumstances, and its purpose is to provide a rubber hose that is inexpensive, has excellent properties such as gasoline resistance, sour gasoline resistance, and heat resistance, and is also excellent in low-temperature properties. do.

[Means for solving problems]

In order to achieve the above object, the rubber hose of this invention has the following features:
Comprising an outer tube rubber layer and an inner tube rubber layer located inside the outer tube rubber layer,
The inner tube rubber layer is composed of a compound containing a small amount of chlorinated polyethylene rubber and chlorosulfonated polyethylene rubber (one of which is the main component), and the outer layer is a compound containing a blend polymer of acrylic rubber and fluororesin as the main component. The structure is formed by an inner layer consisting of.

That is, in constructing a rubber hose using the blended polymer of acrylic rubber and fluororesin, the inventors used the blended polymer as the constituent material of the inner layer of the inner tube rubber layer, and used the blended polymer as the constituent material of the outer layer. The test was conducted using as NBR. As a result, in the structure described above, the plasticizer in the blended polymer migrates into the outer layer made of NBR, and the excellent low-temperature properties of the blended polymer itself are reduced, resulting in a decrease in the low-temperature properties of the entire inner layer. It has become clear that this will occur. Therefore, the present inventors conducted a series of further studies with the aim of preventing the occurrence of such phenomena, and as a result, they decided to use chlorinated polyethylene rubber (hereinafter referred to as rCPE) as a compound for forming the outer layer of the inner tube rubber layer. ) and chlorosulfonated polyethylene rubber (rC
The inventors have discovered that when 5M is used alone or in combination, migration of the plasticizer from the blended polymer of the inner layer can be prevented, and deterioration of the low-temperature properties of the entire inner layer can be prevented, and this invention has been achieved.

The rubber hose of the present invention is obtained by using a compound containing a blend polymer of acrylic rubber and fluororesin as a main component, and a compound containing at least one of CPE and C3M.

The acrylic rubbers used in the blend polymer of acrylic rubber and fluororesin include the following (A) and (B).
), (C) and (D) are preferably used as essential copolymer components.

(A) (meth)acrylic acid alkyl ester.

(B) (meth)acrylic acid-valent group-substituted alkyl ester.

(C) At least one compound selected from a diene compound, a dihydrodicyclopentadienyl group-containing ester of (meth)acrylic acid, an epoxy group-containing ethylenically unsaturated compound, and an active halogen-containing ethylenically unsaturated compound.

(D) Other ethylenically unsaturated compounds copolymerizable with the above (A), (B), and (C).

The (meth)acrylic acid alkyl ester of (A) above is represented by the following general formula (1), and R2 usually consists of 3 to 8 alkyl groups. Specific examples include n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, ? -Ethylhexylacrylate.

The (meth)acrylic acid-valent group-substituted alkyl ester (B) above is represented by the following general formula (2), and R3 includes an alkoxy-substituted alkyl group and a cyano-substituted alkyl group. The alkoxy-substituted alkyl group usually consists of an alkyl group having 1 to 4 carbon atoms substituted with an alkoxy group having 1 to 4 carbon atoms. Moreover, the cyano-substituted alkyl group consists of a cyanoalkyl group having 2 to 12 carbon atoms.

Specific examples of R3 being an alkoxy-substituted alkyl group include methoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, and butoxyethyl acrylate.

Examples include methoxyethoxyethyl acrylate and ethoxyethoxyethyl acrylate.

Specific examples of R3 being a cyanoalkyl group include cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-cyanopropyl (meth)acrylate, Examples include 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate, 2-ethyl-6-cyanohexyl (meth)acrylate, and 8-cyanooctyl (meth)acrylate. Particularly preferred are 2-cyanoethyl acrylate, 3
-Cyanopropyl acrylate 4-cyanobutyl acrylate.

Furthermore, among the above component (C), diene compounds include non-conjugated dienes such as alkylidenenorbornene, alkenylnorbornene, dicyclopentadiene, methylcyclopentadiene and dimers thereof, and conjugated dienes such as butadiene and isoprene. can give. Particularly suitable are alkylidenenorbornene and alkenylnorbornene.

A non-conjugated diene selected from the group consisting of dicyclopentadiene, methylcyclopentadiene and dimers thereof.

Further, among the above component (C), examples of the dihydrodicyclopentadienyl group-containing ester include dihydrodicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyloxyethyl (meth)acrylate, and the like.

In addition, among the above components (C), the epoxy group-containing ethylenically unsaturated compounds include allyl glycidyl ether,
Examples include glycidyl methacrylate and glycidyl acrylate.

Furthermore, among the above components (C), the active halogen-containing ethylenically unsaturated compounds include vinylbenzyl chloride and vinylbenzyl bromide.

2-Chlorethyl vinyl ether, vinyl chloroacetate, vinyl chloropropionate, allyl chloroacetate, allyl chloropropionate 2-chloroethyl acrylate, 2-chloroethyl methacrylate, chloromethyl vinyl ketone, 2-chloroacetoxy-methyl-5 - Examples include norbornene. Among these, vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinylbenzyl chloride,
2-Chlorethyl methacrylate and 2-chloroethyl acrylate give good results.

Examples of other ethylenically unsaturated compounds of component (D) that can be copolymerized with (A), (B), and (C) include acrylic acid, methacrylic acid, and crotonic acid.

Carboxyl group-containing compounds such as 2-pentenoic acid, maleic acid, fumaric acid, and itaconic acid, methacrylates such as methyl methacrylate, octyl methacrylate, alkoxyalkyl acrylates such as methoxyethyl acrylate and butoxyethyl acrylate, and alkyl vinyl ketones such as methyl vinyl ketone. , vinyl ethyl ether,
Vinyl and allyl ethers such as allyl methyl ether, vinyl aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, and vinyltoluene, vinyl nitriles such as acrylonitrile and methacrylonitrile, and vinyl amides such as acrylamide, methacrylamide, and N-methylolacrylamide. , vinyl chloride, vinylidene chloride, alkyl fumarate, etc.

The acrylic rubber in the above blend polymer is the above (
A), (B), (C) and (D) are obtained as essential copolymerization components, and the composition ratio is usually (A).
) is 30-80% (hereinafter abbreviated as "%"), (B) is 20-70%, (C) is 0.5-10%, and (D) is 1-1%.
Set to 30%. When the content of component (A) is below the above range, sufficient heat resistance cannot be obtained, and when it exceeds the above range, the normal physical properties tend to be poor. Furthermore, if the component (B) is below the above range, it will be difficult to obtain sufficient performance in terms of gasoline resistance, sour gasoline resistance, etc. On the other hand, if it exceeds the above range, the normal physical properties will tend to be poor. . Furthermore, if the above-mentioned (C) component and (D) component exceed the above-mentioned range, the balance of gasoline resistance, sour gasoline resistance, heat resistance, etc. will be lost, which is not preferable.

The fluororesin used in the blend polymer of acrylic rubber and fluororesin is polyvinyl fluoride (PVF).
), polyvinylidene fluoride (PDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE). .

In the rubber hose of the present invention, the inner layer of the inner tube rubber layer is formed using a compound mainly composed of a blend polymer of the above-mentioned acrylic rubber and fluororesin, and the compound includes the above-mentioned acrylic rubber, In addition to the fluororesin, usual compounding agents such as reinforcing agents, fillers, plasticizers, softeners, crosslinking agents, stabilizers, etc. are blended as necessary and crosslinked. Furthermore, polymers such as polyvinyl chloride and epichlorohydrin rubber may be blended as necessary.

The rubber hose of the present invention has an outer layer formed of a compound mainly composed of a chlorinated synthetic rubber such as CPE or C3M on the outside of the inner layer obtained using the above compound. , this is a major feature.

The above CPE and C3M have a combined chlorine content of 30 to 50
% is used. That is, by using a synthetic rubber (CPE, C3M) with a high amount of bound chlorine as described above, migration of the plasticizer from the blend polymer of the inner layer can be effectively prevented. Therefore, chlorine-based synthetic rubber (CPE, C3M) in which the amount of combined chlorine is within the above range
It is preferable to use the following in terms of effectiveness.

In addition, as for the compound mainly composed of the above-mentioned chlorinated synthetic rubber (CPE, C3M), conventionally known compounding agents such as reinforcing agents and fillers are added, as in the above-mentioned compound constituting the inner layer of the inner tube rubber layer. etc. can be blended as necessary.

The rubber base of this invention is the above-mentioned chlorinated synthetic rubber (CP
E, CSM), an outer layer consisting of a compound (chlorinated synthetic rubber compound) as the main component, and an inner layer consisting of a compound (blend polymer compound), the main component of which is a blend polymer of acrylic rubber and fluororesin. Such a rubber hose can be manufactured, for example, as follows. That is, a chlorinated synthetic rubber compound kneaded with a cooling roll and a blend polymer compound obtained in the same manner are simultaneously extruded into two layers using an extruder, or an inner layer (blended polymer compound compound) is extruded using two extruders. The inner tube rubber layer is formed by extruding the outer layer (chlorinated synthetic rubber compound layer) on top of the inner tube rubber layer, then the fiber reinforcement layer is formed on top of that, and then the outer tube rubber layer is extruded using an extruder. It can be manufactured by integrating the parts and then vulcanizing and adhering them. The vulcanization conditions in this case are usually set at a temperature of 145 to 170°C for 9 hours and 30 to 90 minutes. The rubber hose thus obtained is shown in FIG. In the figure, 1a shows an inner layer made of a blended polymer compound, 1b shows an outer layer made of a chlorinated synthetic rubber compound, and the inner tube rubber layer has a double structure of the above-mentioned inner layer 1a and outer layer 1b. . 2 is a fiber reinforcing layer similar to the conventional one, and 3 is an outer tube rubber layer.

The rubber hose thus obtained has gasoline resistance,
It has excellent properties such as sour gasoline resistance, sour gasohol resistance, and heat resistance, and is inexpensive, and does not show deterioration in low-temperature properties as seen in blend polymers of acrylic rubber and fluororesin. It has excellent low temperature properties.

〔Effect of the invention〕

Since the rubber hose of the present invention is constructed as described above, it has excellent properties such as gasoline resistance, sour gasoline resistance, sour gasohol resistance, and heat resistance, is inexpensive, and has excellent low-temperature properties. Are better. Therefore, it can sufficiently withstand use under harsh conditions and has the optimum characteristics as a fuel rubber hose for automobiles, etc., which requires high-pressure sealing performance over a long period of time.

Next, examples will be described together with comparative examples.

[Examples 1 to 7, Comparative Example 1.2] First, eight types of chlorinated synthetic rubber compounds shown in Table 1 below were prepared as chlorinated synthetic rubber compounds. In addition, the first
In the table, N is a sulfur-cured product, CP-1 to CP-3
, C3-3 is a peroxide vulcanized product, C3-1, C3
-2 is an amine vulcanized product, and C3-4 is a maleimide vulcanized product.

(The following is a blank space) Next, a blend having the following composition was prepared as a blend polymer blend.

FR-11 (acrylic rubber containing 35% vinylidene fluoride resin (prototype manufactured by Japan Synthetic Rubber Co., Ltd.)): 100 parts by weight stearic acid 1 l5AF
Carbon: 30 Plasticizer (TP-95, manufactured by Thiokol): 25 Vulcanizing agent (Diac Nαl, manufactured by DuPont) 1 In addition, epichlorohydrin rubber was prepared as a material for forming the outer tube rubber layer.

Next, using the above raw materials, an inner tube rubber layer, a fiber reinforced layer, and an outer tube rubber layer were formed by extrusion to manufacture a rubber hose. The structure of the inner tube rubber layer in this case is shown in Table 2 below, and the structure of the outer tube rubber layer is also shown in the same table. In addition, in the same table, A indicates a blend polymer formulation, and N and CP-1 to CP-3, C3-1 to C3-
4 represents the formulation shown in Table 1. Further, C indicates epichlorohydrin rubber.

The rubber hose thus obtained was subjected to bending stress, low temperature bending tests and heat resistance tests. The results are also shown in the same table.

(The following is a blank space) The bending stress and low temperature bending tests in Table 2 were conducted as follows.

(Bending stress) The force required to bend a hose with a length of 200 mm with a radius of curvature of 25 I++++ is shown in g. A larger value indicates less elasticity.

(Low temperature bending test) The above test temperature is shown at which no breakage occurs when the hose is cooled for 5 hours at the test temperature and then wound around a mandrel having a diameter 5 times the outer diameter of the hose.

(Heat Resistance) After aging the hose at 125°C for 1000 hours, it was folded in half at 180° from the middle, and then the hose was cut lengthwise to examine the presence or absence of cracks. Items with cracks×
, Items that are not included are marked with a circle.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a cross-sectional view of a conventional example, and FIG. 3 is a vertical cross-sectional view showing the state in which it is used. 1... Inner tube rubber layer 1a... Inner layer 1b... Outer layer 2... Reinforcement layer 3... Outer tube rubber layer 4... Rubber hose Figure 1 Figure 2 Figure 30

Claims (2)

[Claims] (1) An outer tube comprising an outer tube rubber layer and an inner tube rubber layer located inside the outer tube rubber layer, where the inner tube rubber layer is made of a compound containing at least one of chlorinated polyethylene rubber and chlorosulfonated polyethylene rubber as a main component. 1. A rubber hose, characterized in that it is formed of a layer and an inner layer made of a compound whose main component is a blended polymer of acrylic rubber and fluororesin. (2) The rubber hose according to claim 1, wherein the chlorinated polyethylene rubber or chlorosulfonated polyethylene rubber has a bound chlorine content of 30 to 50% by weight.