JPH0464503B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] 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. [Prior Art] Conventionally, as shown in Fig. 2, rubber hoses for fuel have an inner tube rubber layer 1 having gasoline resistance.
, fiber reinforcing layer 2 and weather-resistant outer tube rubber layer 3
As shown in FIG. It's getting old. However, in recent years, the automobile industry has developed significantly, and in particular, due to the higher pressure and higher temperature of fuel due to measures against car exhaust, the temperature inside the engine compartment has a very wide range of changes from high temperatures of over 100 degrees Celsius to constant temperatures of below -40 degrees Celsius. I am starting to receive this. In addition, automobile fuel rubber hoses are subject to various harsher conditions than conventional ones, such as when gasoline is oxidized and circulated as sour gasoline (gasoline is oxidized at high temperatures and contains peroxide). The reality is that various performances are required, and it is becoming impossible 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, fluorocarbon rubber (hereinafter abbreviated as "FKM") is a material that satisfies the above performance.
Excellent sour gasoline resistance. 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 further made into two layers, and the inner layer of the two layers is
It has been attempted to use thin FKM and form the outer layer with hydrin rubber or acrylonitrile-butadiene rubber (hereinafter abbreviated as "NBR") << low nitrile content and good low-temperature properties >>, which have good low-temperature properties. Note that this method is still not satisfactory in terms of cost and the like. [Problems to be solved by the invention] On the other hand, a composite of acrylic rubber and fluororesin ( Blend) polymers have been developed. However, this blend polymer
Since it is a blend, it has a high hardness after vulcanization, and when this is used, there is a problem with the flexibility of the hose. Therefore, it is desired to provide a rubber hose that is inexpensive, has all the characteristics required for a fuel rubber hose, and also has excellent low-temperature characteristics. This invention was made in view of the above circumstances, and its purpose is to provide a rubber hose that is inexpensive and 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 the Problems] In order to achieve the above object, the rubber hose of the present invention includes an outer tube rubber layer and an inner tube rubber layer located inside the outer tube rubber layer, and the inner tube rubber layer is chlorinated. It is formed of an outer layer made of a compound mainly composed of at least one of polyethylene rubber and chlorosulfonated polyethylene rubber, and an inner layer made of a compound mainly composed of a blend polymer of acrylic rubber and fluororesin. The composition is that there is. That is, in constructing a rubber hose using the blended polymer of the acrylic rubber and fluororesin, the present inventors used the blended polymer as the constituent material of the inner layer of the inner tube rubber layer, and changed the composition of the outer layer. Tests were conducted using NBR as the material. As a result, in the structure described above, the plasticizer in the blend polymer migrates into the outer layer made of NBR, reducing the excellent low-temperature properties of the blend polymer itself, and causing 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 developed a compound for forming the outer layer of the inner tube rubber layer, using chlorinated polyethylene rubber (hereinafter referred to as " CPE) and chlorosulfonated polyethylene rubber (hereinafter referred to as "CSM"), alone or in combination, prevent plasticizer migration from the blended polymer of the inner layer and improve the low-temperature properties of the entire inner layer. This invention was achieved by discovering that the deterioration of the condition can be prevented. The rubber hose of the present invention is obtained by using a blend containing a blend polymer of acrylic rubber and fluororesin as a main component, and a blend containing at least one of CPE and CSM. The acrylic rubber used in the above blend polymer of acrylic rubber and fluororesin is a multicomponent copolymer rubber obtained by using the following (A), (B), (C) and (D) as essential copolymer components. It is preferable to use one consisting of: (A) (Meth)acrylic acid alkyl ester. (B) (Meth)acrylic acid monovalent 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 that can be copolymerized with (A), (B), and (C) above. The (meth)acrylic acid alkyl ester in (A) above is represented by the following general formula (1) [R ₁ is H or CH ₃ , R ₂ is an alkyl group. ], and R ₂ usually consists of 3 to 8 alkyl groups. A specific example of this is n
-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, and 2-ethyl-hexyl acrylate. In addition, the (meth)acrylic acid monovalent group-substituted alkyl ester of (B) above is represented by the following general formula (2). [R ₁ is H or CH ₃ , R ₃ is an alkyl group having a substituent. ], and examples of R ₃ include an alkoxy-substituted alkyl group and a cyano-substituted alkyl group. An alkoxy-substituted alkyl group usually has 1 to 4 carbon atoms substituted with an alkoxy group having 1 to 4 carbon atoms.
It consists of an alkyl group. Further, the cyano-substituted alkyl group consists of a cyanoalkyl group having 2 to 12 carbon atoms. Specific examples of R ₃ being an alkoxy-substituted alkyl group include methoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate,
Examples include methoxyethoxyethyl acrylate and ethoxyethoxyethyl acrylate. In addition, as a specific example of R ₃ being a cyanoalkyl group,
Cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (methane)acrylate, 2-cyanopropyl (meth)acrylate, 3-cyanopropyl (meth)acrylate
Examples include 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, and 4-cyanobutyl acrylate. Furthermore, among the above components (C), diene compounds include non-conjugated dienes such as alkylidenenorbornene, alkenylnorbornene, dicyclopentadiene, methylcyclopentadiene and dimers thereof, and conjugated dienes such as butadiene and isoprene. . Particularly preferred are non-conjugated dienes selected from the group consisting of alkylidenenorbornene, alkenylnorbornene, dicyclopentadiene, methylcyclopentadiene and dimers thereof. In addition, among the above components (C), the dihydrodicyclopentadienyl group-containing esters include dihydrodicyclopentadienyl (meth)acrylate,
Examples include dihydrocyclopentadinyloxyethyl (meth)acrylate. Further, among the above-mentioned component (C), examples of the epoxy group-containing ethylenically unsaturated compound include allyl glycidyl ether, glycidyl methacrylate, and glycidyl acrylate. Furthermore, among the above components (C), the active halogen-containing ethylenically unsaturated compounds include vinylbenzyl chloride vinylbenzyl bromide, 2-chloroethyl vinyl ether, vinyl chloroacetate, vinyl chloropropionate, allyl chloroacetate, Allyl chlorpropionate, 2
-Chlorethyl acrylate, 2-chloroethyl methacrylate, chloromethyl vinyl ketone, 2
-chloroacetoxy-methyl-5-norbornene and the like. Among these, vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinylbenzyl chloride,
-Chlorethyl methacrylate, 2-chloroethyl acrylate gives good results. Other ethylenically unsaturated compounds copolymerizable with (A), (B), and (C) of component (D) above include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, Compounds containing carboxyl groups such as maleic acid, fumaric acid, itaconic acid, methyl methacrylate,
Methacrylates such as octyl methacrylate, alkoxyalkyl acrylates such as methoxyethyl acrylate, butoxyethyl acrylate,
Alkyl vinyl ketones such as methyl vinyl ketone, vinyl and allyl ethers such as vinyl ethyl ether, allyl methyl ether, styrene,
Vinyl aromatic compounds such as α-methylstyrene, chlorostyrene, vinyltoluene, vinyl nitriles such as acrylonitrile and methacrylonitrile,
Examples include vinylamides such as acrylamide, methacrylamide, and N-methylolacrylamide, vinyl chloride, vinylidene chloride, and alkyl fumarates. The acrylic rubber in the above blend polymer is obtained by using the above (A), (B), (C), and (D) as essential copolymer components, and the composition ratio is usually 30 to 30% of (A). 80% by weight (hereinafter abbreviated as "%"), (B)
is set at 20-70%, (C) at 0.5-10%, and (D) at 1-30%. 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. Also,
When the content of component (B) is below the above range, it becomes difficult to obtain sufficient performance in terms of gasoline resistance, sour gasoline resistance, etc. On the other hand, when it exceeds the above range, normal physical properties tend to be poor. Furthermore, if the above-mentioned components (C) and (D) exceed the above ranges, the balance of gasoline resistance, sour gasoline resistance, heat resistance, etc. will be lost, which is not preferable. The fluororesins used in the blend polymer of the above acrylic rubber with fluororesin include polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-hexafluoroethylene. Examples include propylene 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, ordinary 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 this invention has CPE, CSM on the outside of the inner layer obtained using the above-mentioned formulation.
The outer layer is formed from a compound whose main component is a chlorinated synthetic rubber such as chlorine-based synthetic rubber, and this is a major feature. For the above CPE and CSM, the amount of combined chlorine is 30~
50% is used. That is, by using a synthetic rubber (CPE, CSM) 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, from the viewpoint of effectiveness, it is preferable to use a chlorinated synthetic rubber (CPE, CSM) in which the amount of bound chlorine is within the above range. In addition, regarding the compound mainly composed of the above-mentioned chlorinated synthetic rubber (CPE, CSM), as with the compound constituting the inner layer of the inner tube rubber layer, conventionally known compounding agents such as reinforcing agents and fillers may be added. etc. can be blended as necessary. The rubber hose of this invention has an outer layer made of a compound (chlorinated synthetic rubber compound) mainly composed of the above-mentioned chlorinated synthetic rubber (CPE, CSM), and a blended polymer of acrylic rubber and fluororesin as its main component. and an inner layer consisting of a blended polymer blend (blended polymer blend), and 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. An inner tube rubber layer is formed by extruding an outer layer (a chlorinated synthetic rubber compound layer) on top of the material layer, a fiber reinforced layer is then formed on top of the inner tube rubber layer, and an outer tube rubber layer is further extruded using an extruder. It can be manufactured by integrating and then vulcanizing and adhering. The vulcanization conditions in this case are usually set at a temperature of 145 to 170°C and a time of 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 excellent properties such as gasoline resistance, sour gasoline resistance, sour gasohol resistance, and heat resistance, is inexpensive, and is made of a blend of acrylic rubber and fluororesin. There is no deterioration in low-temperature properties as seen with polymers, and it has excellent low-temperature properties. [Effects 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, and is inexpensive. It also has excellent low temperature properties. Therefore, it can sufficiently withstand use under harsh conditions, and has the optimum characteristics for automobile fuel rubber hoses, etc., which require high-pressure sealing performance over a long period of time. Next, examples will be described together with comparative examples. Examples 1 to 7, Comparative Examples 1 and 2 First, as a chlorinated synthetic rubber compound, the following
Eight types of chlorinated synthetic rubber compounds shown in the table were prepared. In Table 1, N is a sulfur-cured product, CP-1 to CP-3, CS-3 are peroxide-cured products, CS-1 and CS-2 are amine-cured products, and CS- 4 is a maleimide vulcanized product.

[Table] Next, a blend of 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 ISAF carbon: 30 Plasticizer (manufactured by Thiokol Co., Ltd., TP-95): 25 〃 Vulcanizing agent (manufactured by Dupont, Diac No. 1)
:1 In addition, epichlorohydrin rubber was prepared as a material for forming the outer tube rubber layer. Next, using the above raw materials, the fiber reinforced layer of the inner tube rubber layer and the 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 and CS-1 to CS-4 indicate the formulations shown in Table 1. Further, C indicates epichlorohydrin rubber. Regarding the rubber hose obtained in this way,
Bending stress, low temperature bending test and heat resistance test were conducted. The results are also shown in the same table.

【table】

[Table] The bending stress and low temperature bending tests shown in Table 2 were conducted as follows. <<Bending Stress>> The force required to bend a 200 mm long hose with a curvature radius of 25 mm is expressed 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>> The hose was aged at 125°C for 1000 hours, then folded in half at 180° from the middle, and then cut open lengthwise to examine the presence of cracks. Those with cracks are marked with an ×, and those with no cracks are marked with an ○.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, and FIG.
The figure is a cross-sectional view of a conventional example, and FIG. 3 is a vertical cross-sectional view showing how 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.

Claims (1)

[Scope of Claims] 1 A compound comprising an outer tube rubber layer and an inner tube rubber layer located inside the outer tube rubber layer, the inner tube rubber layer 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 an outer layer made of a material 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.