JPH0464502B2 - - 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 higher pressure and higher temperatures of fuel due to measures against car exhaust emissions, the temperature inside the engine room can vary widely from high temperatures of over 100 degrees Celsius to low temperatures of below -40 degrees Celsius. It is becoming more and more popular. 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
Although it has been attempted to use thin FMK and form the outer layer with hydrin rubber or NBR (a material with low nitrile content and good low-temperature properties), this method is still unsatisfactory in terms of cost, etc. It's not a thing. [Problems to be solved by the invention] On the other hand, a composite material of acrylic rubber and fluororesin ( Blend) polymers have been developed. However, since this blend polymer is a blend body, 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 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 these circumstances, and is inexpensive, gasoline resistant, sour gasoline resistant,
The purpose of the present invention is to provide a rubber hose that has excellent properties such as heat resistance and also has excellent low-temperature properties. [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 made of acrylonitrile. - formed of an outer layer made of a compound mainly composed of butadiene rubber, and an inner layer made of a compound mainly composed of a blend polymer of acrylic rubber and fluororesin; The compound contains more than 15 parts by weight per 100 parts by weight of acrylonitrile-butadiene rubber with an acrylonitrile content of 30 to 55% by weight.
It is composed of a compound containing 80 parts by weight or less of a plasticizer. 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 NBR. As a result, in the structure described above, the plasticizer in the blend polymer migrates into the NBR outer layer, reducing the excellent low-temperature properties of the blend polymer itself, resulting in a decrease in the low-temperature properties of the entire inner layer. It became clear. Therefore, the present inventors conducted a series of further studies aimed at preventing the occurrence of such phenomena, and as a result, acrylonitrile (hereinafter referred to as "AN") was developed as a compound for forming the outer layer of the inner tube rubber layer. A formulation that uses NBR with a content of 30 to 55% by weight (hereinafter referred to as "%") and contains more than 15 parts and less than 80 parts of a plasticizer per 100 parts by weight (hereinafter referred to as "parts") of NBR. The inventors have discovered that using a plasticizer prevents the plasticizer from migrating from the blended polymer of the inner layer, thereby preventing deterioration of the low-temperature properties of the entire inner layer, and has thus arrived at the present invention. The rubber hose of this invention is made of a compound mainly composed of a blended polymer of acrylic rubber and fluororesin, and 15 parts of NBR with an AN content of 30 to 55%.
It is obtained using a formulation containing more than 80 parts of plasticizer. 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 copolymerizable 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-
Examples include 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. The acyno-substituted or alkyl group is 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 (meth)acrylate, 2-cyanopropyl (meth)acrylate
Acrylate, 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate,
Examples include 2-ethyl-6-cyanohexyl (meth)acrylate and 8-cyanooctyl (meth)acrylate. Particularly preferred are 2-cyanoethyl acrylate, 3-cyanopropyl acrylate, and 4-cyanobutyl acrylate. Further, among the above-mentioned 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. 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 dihydrodicyclopentadienyloxyethyl (meth)acrylate. Furthermore, among the above components (C), examples of the epoxy group-containing ethylenically unsaturated compound include allyl glycyl 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-
Chlorethyl vinyl ether, vinyl chloroacetate, vinyl chloropropionate, allyl chloroacetate, allyl chloropropionate,
2-chloroethyl acrylate, 2-chloroethyl methacrylate, chloromethyl vinyl ketone,
Examples include 2-chloroacetoxy-methyl-5-norbornene. Among these, vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinylbenzyl chloride,
2-Chlorethyl methacrylate and 2-chloroethyl acrylate give good results. Other ethylenically unsaturated compounds of component (D) that can be copolymerized with (A), (B), and (C) include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, and maleic acid. , carboxyl group-containing compounds such as fumaric acid and 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, acrylonitrile,
Vinyl nitrile such as methacrylonitrile, vinylamide such as acrylamide, methacrylamide, N-methylolacrylamide, vinyl chloride,
Examples include vinylidene chloride and alkyl fumarate. The acrylic rubber in the above blend polymer is obtained as essential copolymerization components of (A), (B), (C), and (D), and the composition ratio is usually 30 to 80% of (A). %, (B) 20-70%, (C) 0.5-10
%, (D) is set to 1 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 components (C) and (D) exceed the above-mentioned ranges, the balance of gasoline resistance, sour garine resistance, heat resistance, etc. will be lost, which is not preferable. Examples of the fluororesin used in the above blend polymer of acrylic rubber and 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 PVC and epichlorohydrin rubber can be blended as necessary. The rubber hose of this invention has an outer layer made of a special NBR compound containing a large amount of plasticizer on the outside of the inner layer obtained using the above-mentioned compound. It is a characteristic. As the above-mentioned NBR, one having an AN content of 30 to 55% is used. There are no particular restrictions on plasticizers, and they have been used conventionally.
Examples include synthetic plasticizers such as DBP, DOP, and TCP, and polyhydric alcohols such as ethylene glycol and diethylene glycol. The amount of these plasticizers used needs to be set at a ratio of more than 15 parts and less than 80 parts per 100 parts of NBR having the above AN content. In other words, by forming the outer layer using NBR with the above AN content and a blend of plasticizer in the above ratio with respect to NBR, plasticization from the blended polymer of the inner layer can be achieved for the first time. The above AN
If the content and proportion of the plasticizer are out of the above range, the effects of the present invention cannot be obtained. Regarding the above-mentioned compound consisting of NBR and plasticizer, conventionally known compounding agents such as reinforcing agents, fillers, etc. may be added as necessary, as in the above-mentioned compound constituting the inner layer of the inner tube rubber layer. Can be blended. The rubber hose of this invention has an outer layer made of a compound mainly composed of NBR (NBR compound) and a compound mainly composed of a blend polymer of acrylic rubber and fluororesin (blend polymer compound). It is equipped with an inner layer,
Such a rubber hose can be manufactured, for example, as follows. That is, an NBR blend kneaded with a cooling roll and a similarly obtained blended polymer blend are simultaneously extruded into two layers using an extruder, or an inner layer (blended polymer blend) is extruded using two extruders. An inner tube rubber layer is formed by extruding an outer layer (NBR compound layer) on top of the inner tube rubber layer, a fiber reinforcement layer is then formed on top of the inner tube rubber layer, and an outer tube rubber layer is further extruded using an extruder to integrate the inner tube rubber layer. It can then be manufactured by vulcanization bonding. 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 an NBR compound, and the inner tube rubber layer is the inner layer 1 made of a blended polymer compound.
It has a double structure consisting of a layer a and an 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 obtained in this way has excellent properties such as gasoline resistance, sour gasoline resistance, and heat resistance, and is inexpensive, as well as being similar to that seen in blended polymers of acrylic rubber and fluororesin. No deterioration in low-temperature properties was observed, and the material had 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, and heat resistance, is inexpensive, and has excellent low-temperature properties. Are better. Therefore, it can withstand use under severe 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 5, Comparative Examples 1 and 2 First, six types of NBR blends shown in Table 1 below were prepared as NBR blends.

[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 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, epichlordrin 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-1
to N-6 indicate the NBR formulations shown in Table 1. Further, C indicates epichlorohydrin rubber. Regarding the rubber hose obtained in this way,
Bending stress and low temperature bending tests 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.

[Brief explanation of drawings]

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 its usage. 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 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 an outer layer made of a compound mainly composed of acrylonitrile-butadiene rubber, and an acrylic rubber and fluororesin. and an inner layer consisting of a blend containing a blend polymer as a main component, and the above-mentioned blend containing acrylonitrile-butadiene rubber as a main component is based on 100 parts by weight of acrylonitrile-butadiene rubber having an acrylonitrile content of 30 to 55% by weight. A rubber hose characterized in that it is composed of a compound containing more than 15 parts by weight and less than 80 parts by weight of a plasticizer.