JP6761718B2 - How to make a hose - Google Patents

Description

The present invention relates to a method for manufacturing a bent pipe hose used as a fuel hose, a water hose, an air hose, or the like.

A hose used as a fuel hose, a water-based hose, an air hose, or the like for an automobile is usually manufactured by extruding a rubber material into a hose shape and inserting it into a mandrel and vulcanizing it. The vulcanization is generally carried out under pressure by batch production using a steam can (see, for example, Patent Document 1).

JP-A-2002-225042 Japanese Unexamined Patent Publication No. 2009-121545

However, considering the production efficiency of the hose, continuous production such as performing vulcanization by assembly line is more efficient than performing the vulcanization process by batch production. Further, if the hose can be molded without using the mandrel, it is considered that the production efficiency is further improved because the man-hours for producing the mandrel and removing the mold from the mandrel are eliminated.

However, if vulcanization is carried out in continuous production as described above, it is difficult to carry out vulcanization in a closed space, and as a result, vulcanization is carried out under atmospheric pressure, which causes a problem of rubber foaming. The rubber foaming occurs due to moisture, vulcanization gas, volatile components, etc. in the rubber composition, but since vulcanization by batch production is performed while pressurizing in a closed space, rubber foaming can be suppressed. Vulcanization under atmospheric pressure cannot suppress rubber foaming. When such rubber foaming occurs, there arises a problem that the appearance of the hose is impaired and a problem that the hose performance is hindered such that the elongation of the rubber is shortened (see, for example, Patent Document 2).

In the hose disclosed in Patent Document 2, the problem of rubber foaming is structurally solved by embedding a fiber cord for venting gas along the longitudinal direction of the hose. However, such a hose has a problem that it is difficult to continuously produce such a hose by an assembly line, and more labor and cost are required to bury the fiber cord.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing a hose, which is excellent in hose production efficiency and can solve the problem of rubber foaming during vulcanization.

In order to achieve the above object, the present invention comprises a step of hollowly extruding a rubber composition into a hose having a single-layer structure and then continuously vulcanizing the extruded product under atmospheric pressure. The gist of the hose manufacturing method is a hose manufacturing method using a rubber composition having a minimum torque value of 0.2 Nm or more at 150 ° C. as the rubber composition.

That is, the present inventors have conducted intensive studies to solve the above problems. In the process of the research, the rubber composition is hollow-extruded into a hose shape without using a mandrel, and then vulcanized under atmospheric pressure, and the rubber foaming during the vulcanization is the rubber strength (rubber stress). We considered suppressing it. As a result of repeating various experiments, when a rubber composition having a minimum torque value (ML value) of 0.2 Nm or more at the vulcanization temperature is used as the rubber composition, rubber foaming during the vulcanization is performed. It was found that the rubber strength can be suppressed, and the present invention has been reached.

As described above, the method for producing a hose of the present invention includes a step of hollowly extruding a rubber composition into a hose and then vulcanizing it under atmospheric pressure. The rubber composition has a vulcanization temperature. A rubber composition having a minimum torque value (ML value) of 0.2 Nm or more is used. Therefore, the production efficiency of the hose is excellent, and the problem of rubber foaming during vulcanization can be solved. Since the problem of rubber foaming during vulcanization is solved as described above, in the manufacturing method of the present invention, there is a problem of poor appearance of the hose due to foaming, and hose performance such as shortening of rubber elongation due to foaming. The problem of deterioration can be solved.

In particular, if the rubber composition is hollow-extruded into a hose and then continuously vulcanized under atmospheric pressure, the target hose can be continuously and efficiently produced.

Further, when the rubber composition having a 10% vulcanization time (T10) of 0.1 to 7.0 minutes at the vulcanization temperature is used, the problem of rubber foaming during vulcanization can be further solved. it can.

Further, vulcanization under atmospheric pressure is performed by at least one crosslinking method selected from the group consisting of superheated steam vulcanization, UHF vulcanization, electron beam crosslinking, molten salt crosslinking, hot air furnace, and infrared heating crosslinking. As a result, the problem of rubber foaming during vulcanization can be solved.

Further, when a rubber composition containing a dehydrating agent such as calcium oxide is used as the rubber composition, the problem of rubber foaming during vulcanization can be further solved.

Further, as the rubber composition, at least one selected from the group consisting of a blend polymer (NBR-PVC) of acrylonitrile butadiene rubber and polyvinyl chloride, acrylonitrile butadiene rubber (NBR) and ethylene propylene diene rubber (EPDM) is used. If a rubber composition containing a main component and the minimum torque value at the brewing temperature is 0.2 Nm or more is used, the cost can be reduced because the main component is a general-purpose polymer. Become superior in terms of points.

Then, when the hollow extrusion molding of the rubber composition is performed while unevenly thickening and the hollow curved tube hose shape is formed by using the uneven thickness to form a bent portion, the curved tube hose is continuously and efficiently manufactured. can do.

Next, embodiments of the present invention will be described in detail.

As described above, the method for producing a hose of the present invention includes a step of hollowly extruding a rubber composition into a hose shape and then vulcanizing it under atmospheric pressure, and the rubber composition is added as the rubber composition. A rubber composition having a minimum torque value (ML value) of 0.2 Nm or more at the vulcanization temperature is used. The hollow extrusion molding is usually performed without using a mandrel, but a mandrel may be used if necessary. Further, it is preferable that the hollow extrusion molding and the subsequent vulcanization step are continuously performed from the viewpoint of production efficiency.

Then, by using the rubber composition showing the minimum torque value (ML value) as described above, the problem of rubber foaming during vulcanization under atmospheric pressure can be solved, so that rubber foaming is suppressed. High quality hose can be produced efficiently. From the same viewpoint as above, the minimum torque value (ML value) of the rubber composition is preferably in the range of 0.2 N · m or more, and more preferably in the range of 0.3 to 0.8 N · m. Is. The minimum torque value (ML value) of the rubber composition is a value obtained by reading the value at which the torque is minimized by the method of JIS K 6300-2 vulcanization curve analysis, and the torque is, for example, a rotor. It can be measured with a torqueless type leometer or the like. The above "vulcanization temperature" differs depending on the rubber type. For example, in the case of a blend polymer (NBR-PVC) of acrylonitrile butadiene rubber and polyvinyl chloride, the temperature is 140 to 160 ° C., and the acrylonitrile butadiene rubber (NBR) The temperature is 140 to 160 ° C., the temperature is 140 to 160 ° C. for ethylene propylene diene rubber (EPDM), 150 to 170 ° C. for hydrogenated acrylonitrile butadiene rubber (H-NBR), and acrylic rubber (Acrylic rubber). ACM) is 150-170 ° C, ethylene acrylate rubber (AEM) is 150-170 ° C, chlorinated polyethylene (CM) is 150-170 ° C, and chlorosulfonated polyethylene (CSM). ), The temperature is 140 to 160 ° C., the fluorine rubber (FKM) is 150 to 170 ° C., and the chloroprene rubber (CR) is 140 to 160 ° C.

In particular, if the hollow extrusion molding of the rubber composition is performed while unevenly thickening and the hollow curved tube hose shape is formed by using the uneven thickness to form a bent portion, the curved tube hose can be continuously and efficiently manufactured. can do. Further, by performing hollow extrusion molding while making the thickness uneven as described above, it is possible to manufacture a hose of a curved tube without using a mandrel or a mold. As described above, when the rubber composition is hollow-extruded into a curved tubular shape while being unevenly thickened without using a mandrel or a mold, the obtained unvulcanized rubber hose is affected by the weight and shrinkage of the rubber. There is a concern that the hose may be bent back easily and hose shape retention may be hindered. However, by using the rubber composition having the above physical properties, such a problem can be solved. .. In particular, when the green strength of the rubber composition at 60 ° C. is 0.6 MPa or more, it becomes more excellent from the viewpoint of maintaining the shape of the unvulcanized rubber hose. From the same viewpoint, the green strength is more preferably 0.8 MPa or more. For the green strength of the rubber composition, a JIS No. 1 dumbbell was collected from an unvulcanized sheet preformed using the rubber composition, and a tensile test was conducted in an atmosphere of 60 ° C., and the tensile strength at 25% elongation was obtained. The measured value of stress (M (modulus) 25) was adopted.

Further, after the rubber composition is hollowly extruded into a hose shape, the extruded product is cut to a predetermined length and continuously vulcanized under atmospheric pressure to continuously produce a hose of the desired length. This is preferable because it can be efficiently produced.

Further, when the rubber composition having a 10% vulcanization time (T10) at the vulcanization temperature of 0.1 to 7.0 minutes (6 seconds to 7 minutes) is used, the vulcanization rate is faster. Therefore, the rate at which the rubber strength is increased is high, and the effect of suppressing rubber foaming is further enhanced, which is preferable. From the same viewpoint, the 10% vulcanization time (T10) is more preferably 0.5 to 4.5 minutes (30 seconds to 4 minutes and 30 seconds). The 10% vulcanization time (T10) of the rubber composition is the minimum torque value (ML value) from the time showing the minimum torque value (ML value) by the method of vulcanization curve analysis of JIS K 6300-2. The time until the torque value rises to 10% of the torque difference between the torque value and the maximum torque value (MH value) is read.

Further, vulcanization under atmospheric pressure is performed by at least one crosslinking method selected from the group consisting of superheated steam vulcanization, UHF vulcanization, electron beam crosslinking, molten salt crosslinking, hot air furnace, and infrared heating crosslinking. Since the vulcanization rate of the rubber composition can be increased, the rate at which the rubber strength is increased can be increased, and thus the effect of suppressing rubber foaming becomes higher, which is preferable. The UHF vulcanization means vulcanization by a microwave continuous rubber vulcanization apparatus (UHF). In addition, since it is necessary to give a large amount of energy to the initial vulcanization, superheated steam vulcanization and UHF vulcanization are preferable, and for post-vulcanization, cross-linking with a hot air furnace is performed in order to vulcanize into the rubber. preferable. In the present invention, the vulcanization under atmospheric pressure is not limited to the above-mentioned crosslinking method, and an applicable crosslinking method such as crosslinking by a heating furnace may be performed.

Further, it is preferable to use a rubber composition containing a dehydrating agent as the rubber composition because the problem of rubber foaming caused by evaporation of water in the rubber composition can be effectively solved. As the dehydrating agent, for example, calcium oxide, calcium chloride, silica gel and the like may be used alone or in combination of two or more. Of these, calcium oxide is preferable because it is more excellent in the dehydrating effect of water in the rubber composition. Further, from the viewpoint of obtaining the above effects, the content ratio of the dehydrating agent is preferably in the range of 3 to 20 parts by weight with respect to 100 parts by weight of the rubber component.

Further, as the rubber composition, as described above, a rubber composition having a minimum torque value at the brewing temperature of 0.2 Nm or more is used, and the main component of the rubber composition ( As the rubber component), a blend polymer (NBR-PVC) of acrylonitrile butadiene rubber and polyvinyl chloride, acrylonitrile butadiene rubber (NBR), ethylene propylene diene rubber (EPDM), hydrogenated acrylonitrile butadiene rubber (H-NBR), acrylic Rubber (ACM), ethylene acrylate rubber (AEM), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), fluororubber (FKM), chloroprene rubber (CR) and the like are used. These may be used alone or in combination of two or more. Of these, NBR-PVC, NBR, and EPDM, which are excellent in versatility, are preferably used. The "main component" has a great influence on the characteristics of the entire rubber composition, and in the present invention, it means 20% by weight or more of the total.

In addition to the rubber that is the main component of the rubber composition, the above rubber composition includes a cross-linking agent, a vulcanization accelerator, a vulcanization aid, a retarder, a plasticizer, a co-cross-linking agent, a surface modifier, and an anti-aging agent, if necessary. , Carbon black and other fillers are mixed and kneaded using a kneader such as a kneader, a rubbery mixer or a roll. The minimum torque value at the vulcanization temperature is 0.2 Nm. It is necessary to adjust the composition of each material so as to be as described above. The cross-linking agent used for rubber vulcanization may be a sulfur-based cross-linking agent or a peroxide-based cross-linking agent, but in the production method of the present invention, when the sulfur-based cross-linking agent is used. The effect of suppressing rubber foaming due to the vulcanization gas is well observed.

The hose obtained by the method for manufacturing a hose of the present invention as described above has a single-layer structure, but if necessary, a rubber layer, a resin layer, and a reinforcing thread layer are formed on the outer periphery of the hose having the single-layer structure. Therefore, it may be used as a hose having a multi-layer structure.

The thickness of the innermost layer of the hose (in the case of a single-layer structure, the thickness thereof) is preferably 1 to 15 mm, particularly preferably 2 to 10 mm. The inner diameter of the hose is preferably 6 to 60 mm, particularly preferably 15 to 40 mm. That is, by setting the hose within this range, the dimensional stability required for the hose can be advantageously obtained.

The above hoses can be used for all hoses according to the type of rubber component that is the polymer. For example, fuel hoses such as filler hoses, evaporator hoses, breather hoses, radiator hoses, heater hoses, drain hoses, etc. It can be used as an air hose for water-based hoses, turbo air hoses, vacuum brake hoses, etc. Further, if the hose is a curved tube hose, it becomes easy to bend, so that the hose can be more easily assembled to a vehicle or a system. The hose is suitably used for transport aircraft such as automobiles, tractors, cultivators, and ships, and systems and equipment that require the functions of these hoses.

Next, Examples will be described together with Comparative Examples. However, the present invention is not limited to these examples.

First, the materials shown below were prepared prior to Examples and Comparative Examples.

[NBR-PVC]
Nipol DN508SCR (NBR-PVC oiled with 5% by weight), manufactured by Zeon Corporation

[Vulcanization aid]
2 types of zinc oxide, manufactured by HakusuiTech Co., Ltd.

〔stearic acid〕
Lunac S-70V, manufactured by Kao Corporation

[Anti-aging agent 1]
Antage RD, manufactured by Kawaguchi Chemical Industry Co., Ltd.

[Anti-aging agent 2]
Antage 3C, manufactured by Kawaguchi Chemical Industry Co., Ltd.

[Carbon Black 1]
Asahi # 60, manufactured by Asahi Carbon Co., Ltd.

[Carbon Black 2]
Asahi # 52, manufactured by Asahi Carbon Co., Ltd.

[Plasticizer]
ADEKA Sizar RS-700, manufactured by ADEKA

[Vulcanization accelerator 1]
Accelerator TMT, manufactured by Kawaguchi Chemical Industry Co., Ltd.

[Vulcanization accelerator 2]
Accelerator M, manufactured by Kawaguchi Chemical Industry Co., Ltd.

[Vulcanization accelerator 3]
Accelerator TRA, manufactured by Kawaguchi Chemical Industry Co., Ltd.

[Vulcanization accelerator 4]
Accelerator CZ, manufactured by Kawaguchi Chemical Industry Co., Ltd.

[Crosslinking agent]
Sulfur, manufactured by Tsurumi Chemical Industry Co., Ltd.

[Calcium oxide]
CML-21, manufactured by Omi Chemical Industry Co., Ltd.

[Retarder]
Anscorch CTP, manufactured by Kawaguchi Chemical Industry Co., Ltd.

<< Examples 1 to 5, Comparative Examples 1 to 4 >>
Each of the above components was blended at the ratio shown in Table 1 below (NBR-PVC is the ratio excluding the oil added) and kneaded using a Banbury mixer and an open roll to prepare a rubber composition. Specifically, the components excluding the cross-linking agent and the vulcanization accelerator are kneaded with a rubbery mixer and released when the temperature reaches 150 ° C. to obtain a master batch, and then the cross-linking agent and vulcanization are added to the master batch. Accelerators were blended in the proportions shown in the table, and these were kneaded with an open roll to prepare a rubber composition.

The physical properties of the rubber compositions of Examples and Comparative Examples thus obtained were measured according to the following criteria. The results are also shown in Table 1 below.

<ML value>
The torque of the rubber composition at 150 ° C. is measured by the vulcanization curve analysis method of JIS K 6300-2 with a rotorless rheometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the minimum torque value (ML value) is read. It was.

<Green strength>
A JIS No. 1 dumbbell was collected from an unvulcanized sheet obtained by preforming at 100 ° C. using the above rubber composition, and a tensile test was conducted in an atmosphere of 60 ° C., and the value of tensile stress at 25% elongation. (M (modulus) 25) was measured. Then, the value was taken as the green intensity (MPa).

<T10>
According to the method of vulcanization curve analysis of JIS K 6300-2, the minimum torque value (ML value) and the maximum torque value (MH value) are determined from the time when the rubber composition shows the minimum torque value (ML value) at 150 ° C. The time required for the torque value to rise to 10% of the torque difference was read, and the value was defined as T10.

≪Growth≫
A test piece was cut out from a vulcanized sheet obtained by vulcanizing in a hot air furnace at 160 ° C. for 40 minutes using the above rubber composition, and a tensile test was carried out in accordance with JIS K 6251. %) Was measured.

Using the rubber compositions of Examples and Comparative Examples in which the above physical properties are the values shown in Table 1 below, rubber hoses were prepared according to the following criteria, cross-sectional observation was performed, and evaluation was performed. The results are also shown in Table 1 below.

≪Cross section observation≫
Using the above rubber composition, the rubber composition was hollow-extruded into a tubular shape (cylindrical shape) having an inner diameter of 30 mm and a wall thickness of 4 mm, and then cut into a length of 300 mm. The unvulcanized rubber hose thus obtained was vulcanized with hot air at 160 ° C. for 40 minutes under atmospheric pressure using a hot air furnace to obtain a rubber hose. Then, the obtained rubber hose was cut, and the cross section thereof was observed with an optical microscope (manufactured by KEYENCE) in a viewing range of 20 mm × 3.7 mm, and the number of foams having a diameter of 0.1 mm or more was counted.

From the results in the above table, the rubber composition used as the material of the hose of the example has an ML value of 0.2 Nm or more at the vulcanization temperature, so that the rubber composition is vulcanized under atmospheric pressure. Nevertheless, the cross-sectional observation did not show a number of rubber foams that interfered with the appearance of the hose. In addition, since the rubber foaming was suppressed as described above, the elongation was also suppressed. In addition, the rubber composition used as the material of the hose of the example had high green strength and did not settle after hollow extrusion molding.

On the other hand, the rubber composition, which is the material of the hose of the comparative example, has an ML value of less than 0.2 Nm at the vulcanization temperature, so that the hose looks and stretches when vulcanized under atmospheric pressure. As a result, a large number of rubber foams (the number of foams having a diameter of 0.1 mm or more exceeds 15 in a viewing range of 20 mm × 3.7 mm) were observed so as to hinder the condition.

The method for manufacturing the hose of the present invention is, for example, manufacturing a fuel hose such as a filler hose, an evaporator hose, a breather hose, a water hose such as a radiator hose, a heater hose, and a drain hose, and an air hose such as a turbo air hose and a vacuum brake hose. It can be applied as a method. The hoses obtained by the above manufacturing method can be used for transport aircraft such as automobiles, tractors, cultivators, and ships, and systems and equipment that require the functions of these hoses.

Claims (7)

In a method for producing a hose, which comprises a step of hollowly extruding a rubber composition into a hose having a single-layer structure and then continuously vulcanizing the extruded product under atmospheric pressure, the rubber composition is 150. A method for manufacturing a hose, which comprises using a rubber composition having a minimum torque value of 0.2 Nm or more at ° C. Above for the rubber composition, between the vulcanizing 10% in degree of vulcanization used as a 0.1 to 7.0 minutes The process of claim 1 Symbol mounting of the hose. Claimed that vulcanization under atmospheric pressure is carried out by at least one crosslinking method selected from the group consisting of superheated steam vulcanization, UHF vulcanization, electron beam crosslinking, molten salt crosslinking, hot air furnace, and infrared heating crosslinking. Item 3. The method for manufacturing a hose according to Item 1 or 2 . The method for producing a hose according to any one of claims 1 to 3 , wherein a rubber composition containing a dehydrating agent is used as the rubber composition. The method for manufacturing a hose according to claim 4 , wherein the dehydrating agent is calcium oxide. The main component of the rubber composition is at least one selected from the group consisting of a blend polymer (NBR-PVC) of acrylonitrile butadiene rubber and polyvinyl chloride, acrylonitrile butadiene rubber (NBR) and ethylene propylene diene rubber (EPDM). The method for producing a hose according to any one of claims 1 to 5 , wherein the rubber composition is used and the minimum torque value at the vulcanization temperature is 0.2 Nm or more. The method according to any one of claims 1 to 6 , wherein the hollow extrusion molding of the rubber composition is performed while unevenly thickening, and the hollow curved tube hose shape is formed by forming a bent portion using the uneven thickness. How to make a hose.