JP2017120122A - Hose and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hose produced by extrusion molding and excellent in dimensional stability, and to provide a method for producing the same.SOLUTION: In the hose made of a rubber composition containing cellulose short fiber, the cellulose short fiber 2 is oriented in parallel with a longitudinal direction of the hose 1. The method for producing the hose includes a step of hollow-extrusion molding the rubber composition containing the cellulose short fiber into a hose-shape without using a mandrel and vulcanizing it.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hose used as a fuel hose, an aqueous hose, an air hose, and the like, and a method for producing the hose.

  In fuel hoses used for automobile fuel pipes and the like, a polymer (NBR-PVC) obtained by thermally melting polyvinyl chloride in acrylonitrile butadiene rubber is preferably used as the hose material because of its high fuel barrier properties. . Normally, the hose is manufactured by extruding a rubber material into a hose shape and then bending it using a mandrel. However, in recent years, there is a manufacturing method in which the rubber material is hollow-extruded into a hose shape without using a mandrel. In addition, a technique has also been developed in which a hollow tube hose is manufactured without using a mandrel or a mold by performing hollow extrusion molding with uneven thickness (see, for example, Patent Document 1).

Japanese Patent No. 3374513

  However, when the rubber material is extruded into a hose shape as described above, there is a problem that the dimensional accuracy is reduced due to the occurrence of swell (thickening during extrusion). Conventionally, such swell has been dealt with by pulling an unvulcanized rubber hose during extrusion. However, in such a countermeasure, there is a problem that dimensional accuracy is lowered because shrinkage due to heat during vulcanization increases. Furthermore, in hollow extrusion molding that does not use a mandrel, shrinkage cannot be suppressed by the mandrel when vulcanized, and therefore higher dimensional stability is required. Accordingly, there is a need for a rubber hose with high dimensional stability that addresses these problems.

  In addition, as described above, the hose made of NBR-PVC is useful as a fuel hose because of its excellent fuel barrier property. However, in order to further improve the fuel barrier property, NBR-PVC with a high nitrile amount is used. When is used, there is a problem that the hose sags easily because it is easily softened by heat during vulcanization. This problem is noticeable when a hose is manufactured by hollow extrusion molding, and a solution to this problem is required.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a hose excellent in dimensional stability by extrusion molding and a method for producing the hose.

  In order to achieve the above object, the present invention provides a hose comprising a rubber composition containing short cellulose fibers, wherein the short cellulose fibers are oriented parallel to the longitudinal direction of the hose. One gist.

  The present invention is also a method for producing a hose according to the first aspect, comprising a step of vulcanizing a rubber composition containing short cellulose fibers by hollow extrusion molding into a hose shape without using a mandrel. The manufacturing method of the hose is the second gist.

  That is, the present inventors have intensively studied to solve the above problems. In the course of the study, we examined adding fillers to the rubber composition, which is a hose material, until dimensional stability of the hose can be obtained. However, in order to add the filler until the dimensional stability of the hose can be obtained, a large amount of filler must be added, and problems such as deterioration of extrudability and deterioration of flexibility of the hose are newly introduced. As a result, a filler specialized in improving the dimensional stability of the hose was examined without causing such problems. As a result, when cellulose short fibers were used as a filler, it was found that they have good affinity with the rubber component and show good dispersibility in the rubber component. Even if the cellulose short fibers are not added in a large amount, the cellulose short fibers are oriented in parallel to the longitudinal direction of the hose during the extrusion of the hose, so that the rubber composition flows during the extrusion. Since it shows the action of restraining the extrusion direction in the extrusion direction, problems such as swell caused by the disturbance of the flow of the rubber composition during extrusion can be eliminated, and further, shrinkage during vulcanization can be suppressed, and further, I found out that the reinforcement to the tsunami will also increase. From these facts, it was found that the hose of the present invention in which the short cellulose fibers are oriented in parallel to the longitudinal direction of the hose is a rubber hose having high dimensional stability, and has reached the present invention.

  In addition, in the manufacture of the above-mentioned hose, if the hose is hollow-extruded and vulcanized without using a mandrel, the occurrence of an avatar on the inner peripheral surface of the hose that is sometimes seen during vulcanization using a mandrel can be eliminated. I found out. In addition, the avatar is a bubble mark generated when the water and the release agent accumulated between the mandrel used at the time of manufacturing the hose and the inner peripheral surface of the hose evaporate, and the elastic force of the rubber is lost to the force. In the fuel hose, it can cause fuel leakage. Then, as in the present invention, when a rubber composition containing short cellulose fibers is hollow-extruded into a hose shape without using a mandrel, problems such as swell frequently observed in conventional hollow extrusion molding, The problem of shrinkage during vulcanization and the problem of sag during vulcanization can also be solved. Further, by performing hollow extrusion while making the thickness uneven, it is possible to produce a bent tube hose without using a mandrel or a mold.

  As described above, the hose of the present invention is a hose made of a rubber composition containing cellulose short fibers, in which the cellulose short fibers are oriented parallel to the longitudinal direction of the hose. Therefore, it is excellent in dimensional stability by extrusion molding, and a rubber hose with high dimensional accuracy can be obtained.

  In particular, when the average fiber length of the cellulose short fibers is in the range of 50 to 500 μm, the dimensional stability is further improved.

  Moreover, when the content ratio of the short cellulose fiber in the rubber composition is in the range of 3 to 120 parts by weight with respect to 100 parts by weight of the rubber component, deterioration of extrusion processability, deterioration of extruded skin, deterioration of hardness and elongation. A hose with good dimensional stability can be obtained without causing problems such as deterioration in flexibility of the hose.

  The rubber component in the rubber composition is selected from the group consisting of a blend polymer of acrylonitrile butadiene rubber and polyvinyl chloride (NBR-PVC), acrylonitrile butadiene rubber (NBR), and ethylene-propylene-diene rubber (EPDM). If it is at least one, it is a general-purpose polymer, so that it is excellent in terms of cost reduction.

Further, when the hose of the present invention is made of the rubber composition further containing a dehydrating agent, the problem of rubber foaming caused by evaporation of water in the rubber composition can be effectively solved.
Further, when the hose of the present invention is further composed of the rubber composition having a minimum torque value (ML value) at a vulcanization temperature of 0.2 N · m or more and the rubber composition containing a dehydrating agent, the rubber composition The problem of rubber foaming caused by generation of vulcanized gas in the product and evaporation of moisture can be effectively solved.

  Further, when the hose has a single layer structure, it is excellent in that the manufacturing cost is reduced due to the ease of manufacture.

  In addition, if the hose is a bent tube hose and the outer wall thickness of the bent portion is thicker than the inner wall thickness, the hose can be easily bent inside the R portion. In some cases, it may become superior.

  Moreover, in the manufacture of the above-mentioned hose, when a hollow hose is formed by extrusion without using a mandrel and vulcanized, generation of avatars on the inner peripheral surface of the hose that is sometimes seen during vulcanization using a mandrel can be eliminated. . Then, as in the present invention, when a rubber composition containing short cellulose fibers is hollow-extruded into a hose shape without using a mandrel, problems such as swell frequently observed in conventional hollow extrusion molding, The problem of shrinkage during vulcanization and the problem of sag during vulcanization can also be solved. Further, by performing hollow extrusion while making the thickness uneven, it is possible to produce a bent tube hose without using a mandrel or a mold.

  In the above-described hose manufacturing method, when a rubber composition having a minimum torque value of 0.2 N · m or more at the vulcanization temperature is used as the rubber composition, there is a problem particularly when vulcanizing under atmospheric pressure. The problem of rubber foaming can be solved.

  In the above-described hose manufacturing method, if a rubber composition having a 10% vulcanization time of 0.1 to 7.0 minutes at the vulcanization temperature is used as the rubber composition, the rubber at the time of vulcanization is used. The problem of foaming can be solved more.

  In addition, when the rubber composition further containing a dehydrating agent is used as the rubber composition in the above-described hose manufacturing method, the problem of rubber foaming due to the evaporation of moisture in the rubber composition is effective. Can be eliminated.

It is explanatory drawing which shows an example of the hose of this invention.

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

  The hose of the present invention is a hose made of a rubber composition containing cellulose short fibers, wherein the cellulose short fibers 2 are oriented parallel to the longitudinal direction of the hose 1 as shown in FIG. It is. This “parallel” indicates that it is within 30 ° with respect to the longitudinal direction of the hose. In addition, the arrow part of illustration is a principal part enlarged view which shows the cross-sectional state (orientation state of the cellulose short fiber 2) of the longitudinal direction of the hose 1. FIG. The orientation of the cellulose short fibers can be confirmed by halving the hose in the longitudinal direction and observing the cross section with an SEM (electron microscope).

  The rubber component in the rubber composition includes a blend polymer of acrylonitrile butadiene rubber and polyvinyl chloride (NBR-PVC), 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. Among these, NBR-PVC, NBR, and EPDM that are excellent in versatility are preferably used.

  Cellulose short fibers blended in the rubber composition are short in fiber length of cellulose fibers and can be used as a filler in the material of the hose of the present invention, and are effective in improving the dimensional stability of the hose. It works. And it is preferable that the average fiber length of the said cellulose short fiber is 50-500 micrometers from a viewpoint of the improvement effect of the dimensional stability of a hose. More preferably, short cellulose fibers having an average fiber length of 190 to 370 μm, and more preferably 270 to 330 μm cellulose short fibers are used. That is, if the average fiber length is too short, it is difficult to obtain the effect of improving the dimensional stability required for the present invention. If the average fiber length is too long, the extrudability deteriorates and the hose flexibility deteriorates. This is because problems such as these occur. In addition, the average fiber diameter of the said cellulose short fiber is 10-30 micrometers normally. And the average fiber length and average fiber diameter of the said cellulose short fiber can be measured by SEM (electron microscope) observation etc., for example.

  Further, the content ratio of the short cellulose fibers in the rubber composition is in the range of 3 to 120 parts by weight with respect to 100 parts by weight of the rubber component, deterioration of extrusion processability, deterioration of extruded skin, deterioration of hardness and elongation. From the viewpoint of obtaining a hose having good dimensional stability without causing problems such as deterioration of the flexibility of the hose due to the above. From the same viewpoint, the content ratio of the cellulose short fibers is more preferably in the range of 4 to 50 parts by weight, and still more preferably in the range of 5 to 20 parts by weight. That is, when the content ratio of the cellulose short fibers is too small, it is difficult to obtain the effect of improving the dimensional stability required for the present invention. When the content is too large, the extrudability deteriorates, the extruded skin deteriorates, and the hose becomes flexible. This is because problems such as deterioration of sex will occur.

  The rubber composition which is the material of the hose of the present invention includes a crosslinking agent, a vulcanization accelerator, a vulcanization aid, a retarder, a plasticizer, a co-crosslinking agent, a surface, as necessary, together with the rubber component and the short cellulose fiber. It can be prepared by blending a modifier, an anti-aging agent, a dehydrating agent, a filler such as carbon black, and the like and kneading them using a kneader such as a kneader, a Banbury mixer, or a roll.

  As described above, it is preferable to use a rubber composition containing a dehydrating agent 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 are used alone or in combination of two or more. Among these, calcium oxide is preferable because it is more excellent in the dehydration effect of moisture in the rubber composition. From the viewpoint of obtaining the above effects, the content 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.

  And the hose of this invention can be produced as follows, for example using the rubber composition prepared as mentioned above. That is, first, the rubber composition prepared as described above is extruded into a tubular shape (cylindrical shape) to produce an unvulcanized hose. In addition, the hose of the present invention is characterized by excellent dimensional stability without using a mandrel during the above extrusion molding, but if necessary, a rubber composition may be extruded on the mandrel. . And after extrusion-molding as mentioned above, a desired hose can be obtained by vulcanizing by steam vulcanization or the like under a predetermined condition (140 to 160 ° C. × 30 to 60 minutes).

  In the hose manufacturing method of the present invention, if a hose is hollow-extruded and vulcanized without using a mandrel, the occurrence of an avatar on the inner peripheral surface of the hose that is sometimes seen during vulcanization using a mandrel is eliminated. be able to. Then, as in the present invention, when a rubber composition containing short cellulose fibers is hollow-extruded into a hose shape without using a mandrel, problems such as swell frequently observed in conventional hollow extrusion molding, The problem of shrinkage during vulcanization and the problem of sag during vulcanization can also be solved. Further, by performing hollow extrusion while making the thickness uneven, it is possible to produce a bent tube hose without using a mandrel or a mold.

  By the way, when hollow extrusion molding is performed while uneven thickness is applied as described above, the obtained unvulcanized rubber hose is likely to be bent back and sag due to the stress of the rubber and its own weight, and the shape of the unvulcanized rubber hose is maintained. Although the problem of causing trouble is concerned, such a problem can be solved by using a rubber composition having a green strength of 0.6 MPa or more at 60 ° C. of the rubber composition. From the same viewpoint, the green strength is preferably 0.8 MPa or more. The green strength of the rubber composition was determined by taking a JIS No. 1 dumbbell from an unvulcanized sheet preliminarily molded using the rubber composition, performing a tensile test in an atmosphere of 60 ° C., and stretching at 25% elongation. A value (M (modulus) 25) obtained by measuring the stress was adopted.

  Further, in the above-described hose manufacturing method, when a rubber composition having a minimum torque value of 0.2 N · m or more at the vulcanization temperature is used as the rubber composition, there is a problem particularly during vulcanization under atmospheric pressure. This is preferable because the problem of foaming rubber can be solved. The minimum torque value (ML value) of the rubber composition is more preferably in the range of 0.3 to 0.8 N · m from the same viewpoint as described above. In addition, the minimum torque value (ML value) of the rubber composition is a value obtained by reading a value at which the torque is minimum by the method of vulcanization curve analysis of JIS K 6300-2. It can be measured with a loess-type rheometer or the like. The above-mentioned “vulcanization temperature” varies depending on the rubber type. For example, in the case of a blend polymer of acrylonitrile butadiene rubber and polyvinyl chloride (NBR-PVC), it is 140 to 160 ° C., and acrylonitrile butadiene rubber (NBR). 140-160 ° C. for ethylene-propylene-diene rubber (EPDM), 140-160 ° C. for hydrogenated acrylonitrile butadiene rubber (H-NBR), 150-170 ° C., acrylic rubber (ACM) is 150 to 170 ° C, ethylene acrylate rubber (AEM) is 160 ° C, chlorinated polyethylene (CM) is 150 to 170 ° C, and chlorosulfonated polyethylene (CSM) In the case of 140-160 ° C., and fluoro rubber (FKM) Can is 150-170 ° C., when the chloroprene rubber (CR) is 140 to 160 ° C..

  Furthermore, in the above-described hose manufacturing method, when a rubber composition having a 10% vulcanization time of 0.1 to 7.0 minutes (6 seconds to 7 minutes) at the vulcanization temperature is used as the rubber composition, Since the speed of vulcanization is higher, the speed at which the rubber strength is increased is faster, which is preferable because the problem of rubber foaming during vulcanization can be solved more. From the same viewpoint, the 10% vulcanization time (T10) is more preferably 0.5 to 4.5 minutes (30 seconds to 4 minutes 30 seconds). The 10% vulcanization time (T10) of the rubber composition is determined from the time when the minimum torque value (ML value) is obtained by the method of vulcanization curve analysis of JIS K 6300-2, and the minimum torque value (ML value). 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.

  In the present invention, the problem of rubber foaming means a problem that the appearance of the hose is impaired due to foaming, or a problem that hose performance is hindered such as a short stretch of rubber.

  It is preferable that the hose of the present invention thus obtained has a single-layer structure from the viewpoint of easy manufacturing and lower processing costs. In addition, the hose is a bent tube hose, and the outer wall thickness of the bent shape portion is formed to be thicker than the inner wall thickness. This is preferable from the viewpoint of assembly.

  Further, the hose of the present invention may be formed as a multi-layered hose by forming a rubber layer, a resin layer, and a reinforcing yarn layer on the outer periphery of the single-layered hose obtained as described above, if necessary. Absent.

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

  The hose of the present invention can be used for all hoses depending on the type of the rubber component that is a polymer thereof. For example, fuel hoses such as filler hoses, evaporation hoses, and breather hoses, radiator hoses, heater hoses, and drains. It can be used as an air hose such as a water-based hose such as a hose, a turbo air hose, or a vacuum brake hose. And the said hose is used suitably for transport systems, such as a motor vehicle, a tractor, a cultivator, a ship, and the system and installation which require the function of these hoses.

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

  First, prior to the examples and comparative examples, the following materials were prepared.

[NBR-PVC]
Nipol DN508SCR (NBR-PVC with 5% oil added) manufactured by Nippon Zeon

[NBR]
Nipol DN003, manufactured by Nippon Zeon

[EPDM]
Esprene 505A manufactured by Sumitomo Chemical Co., Ltd.

[Carbon black 1]
Toast Carbon Co., Ltd., Seast V

[Carbon black 2]
Cabot Corporation, Show Black IP200

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

[Zinc oxide]
2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.

[Plasticizer 1]
Made by ADEKA, Adeka Sizer RS-107

[Plasticizer 2]
Made by Idemitsu Oil Co., Diana Process PW-380

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

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

[Surface modifier]
Emaster 510P, manufactured by Riken Vitamin

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

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

[Vulcanization accelerator 3]
Made by Sanshin Chemical Industry Co., Ltd., Sunseller TT-G

[Vulcanization accelerator 4]
Sunseller TET-G, manufactured by Sanshin Chemical Industry Co., Ltd.

[Vulcanization accelerator 5]
Sunseller CZ-G, manufactured by Sanshin Chemical Industry Co., Ltd.

[Vulcanization accelerator 6]
Nouchira BZ-G made by Ouchi Shinsei Chemical Co., Ltd.

[Vulcanization accelerator 7]
Accelerator M, manufactured by Kawaguchi Chemical Industry Co., Ltd.

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

[Crosslinking agent 1]
Sanshin Chemical Industry Co., Ltd., Sunmix S-80NBR

[Crosslinking agent 2]
Sulfax T-10, manufactured by Tsurumi Chemical Co., Ltd.

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

[Cellulose fiber 1]
Cellulose fibers with an average fiber length of 370 μm and an average particle diameter of 25 μm (manufactured by Nippon Paper Industries Co., Ltd., KC Flock W-50GK)

[Cellulose fiber 2]
Cellulose fiber with an average fiber length of 300 μm and an average particle diameter of 25 μm (manufactured by Nippon Paper Industries Co., Ltd., KC Flock W-100GK)

[Cellulose fiber 3]
Cellulose fibers with an average fiber length of 190 μm and an average particle diameter of 16 μm (manufactured by Nippon Paper Industries Co., Ltd., KC Flock W-400G)

〔silica〕
Tosoh Silica Co., Ltd., Nipsil ER

<< Examples 1 to 16, Comparative Examples 1 and 2 >>
Each of the above components was blended in the proportions shown in Tables 1 and 2 below (NBR-PVC is a proportion excluding oil), and kneaded using a Banbury mixer and an open roll to prepare a rubber composition. Specifically, the components excluding the crosslinking agent and the vulcanization accelerator are kneaded with a Banbury mixer and released when the temperature reaches 150 ° C. After obtaining a master batch, the crosslinking agent and the 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.

  Using the rubber compositions of Examples and Comparative Examples thus obtained, rubber hoses were produced according to the following criteria, and each characteristic at that time was evaluated. These results are shown in Tables 1 and 2 below.

≪Vulcanization shrinkage≫
Each rubber composition was hollow-extruded into a tubular shape (cylindrical shape) with an inner diameter of 30 mm and a wall thickness of 4 mm, and then cut into a length of 300 mm. Two unvulcanized rubber hoses thus obtained were prepared, and a straight metal mandrel having an outer diameter of 30 mm was inserted into one, and a mandrel was not inserted into the other. Then, these unvulcanized rubber hoses were pressure vulcanized with steam at 160 ° C. for 20 minutes to obtain rubber hoses.
In addition, the rubber hose in which the mandrel was inserted and vulcanized as described above was defined as “with mandrel”, and the rubber hose vulcanized without the mandrel inserted was defined as “without mandrel”. Then, the vulcanization shrinkage rate of the rubber hose in the case of “with mandrel” and in the case of “without mandrel” was determined by the following formula (1). And the thing whose vulcanization shrinkage rate is 6.5% or less was evaluated as (circle), and the thing whose vulcanization shrinkage rate exceeds 6.5% was evaluated as x.
Vulcanization shrinkage ratio (%) = [(length of unvulcanized rubber hose−length of rubber hose after vulcanization) / length of unvulcanized rubber hose] × 100 (1)

≪Swell≫
The rate of change in the thickness of the hollow extruded product (rubber hose) with respect to the space between the die and the spindle when each rubber composition was subjected to hollow extrusion molding was determined by the following formula (2). And the thing with the change rate of 1-1.24 was evaluated as (circle), and the thing with a change rate exceeding 1.24 was evaluated as x. Rate of change = thickness of hollow extruded product / [(die size−spindle size) / 2)] …… (2)

≪Hardness≫
A test piece was cut out from the rubber hose produced at the time of the above “vulcanization shrinkage” evaluation, and the hardness (JIS-A) of the test piece was measured according to JIS K 6253. And the thing whose hardness is 80 or less was evaluated as (double-circle), and the thing 90 or less was evaluated as (circle).

≪Elongation≫
A test piece was cut out from the rubber hose produced at the time of the above “vulcanization shrinkage” evaluation, a tensile test was performed according to JIS K 6251, and an elongation (%) at break was measured. And the thing whose elongation was 150% or more was evaluated as (circle).

  From the results shown in Tables 1 and 2, it can be seen that the hose of the example is excellent in dimensional stability because the vulcanization shrinkage is small and the occurrence of swell is suppressed. In addition, when the hose of the example was halved in the longitudinal direction and the cross section was observed with an SEM (electron microscope), it was found that the cellulose short fibers were oriented parallel to the longitudinal direction of the hose. .

  On the other hand, the hose of Comparative Example 1 had a higher vulcanization shrinkage rate and a swell as compared with the hose of the Example, resulting in poor dimensional stability. The hose of Comparative Example 2 contains silica and has a slightly higher vulcanization shrinkage and swell than the hose of the Example, resulting in poor dimensional stability.

  In addition, in the rubber hose of the example and the comparative example, when a rubber hose in which the mandrel was inserted and vulcanized and the inner peripheral surface of the hose was visually observed, no avatar was found on the inner peripheral surface of the rubber hose of the example. Bubble marks (avatars) were found on the inner peripheral surface of the rubber hose of the comparative example.

  As further experiments, the following physical properties were measured and evaluated using the rubber compositions of Examples 14, 15 and 16. The results are also shown in Table 3 below.

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

<Green strength>
From an unvulcanized sheet obtained by preforming at 100 ° C. using the rubber composition, a JIS No. 1 dumbbell was collected, subjected to a tensile test in an atmosphere at 60 ° C., and a tensile stress value at 25% elongation. (M (modulus) 25) was measured. And the value was made into green strength (MPa).

<T10>
By 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 calculated from the time when the rubber composition at 150 ° C. exhibits the minimum torque value (ML value). The time until the torque value increased to 10% of the torque difference was read, and the value was defined as T10.

<Elongation>
Using the rubber composition, a test piece was cut out from a vulcanized sheet obtained by atmospheric pressure vulcanization in a hot air oven at 160 ° C. for 40 minutes, and a tensile test was performed in accordance with JIS K 6251. Elongation (%) was measured.

≪Section observation≫
The rubber composition was hollow extruded into a tubular shape (cylindrical shape) with 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 subjected to hot air vulcanization 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 visual field 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 shown in Table 3, the rubber composition as the material of the hose of Examples 14 and 15 has an ML value at the vulcanization temperature of 0.2 N · m or more. Therefore, in spite of vulcanization under atmospheric pressure, a number of rubber foams that hindered the appearance of the hose were not observed from cross-sectional observation. In addition, since foaming of rubber was suppressed as described above, the result was that elongation was also suppressed. In particular, the rubber composition which is the material of the hose of Example 15 further contains calcium oxide which is a dehydrating agent, resulting in the suppression of rubber foaming. Moreover, the rubber composition which is the material of the hose of Examples 14 and 15 had high green strength, and no settling occurred after hollow extrusion molding.

  On the other hand, the rubber composition that is the material of the hose of Example 16 has an ML value at a vulcanization temperature of less than 0.2 N · m. Many rubber foams were observed during vulcanization.

  The hose of the present invention can be used, for example, as a fuel hose such as a filler hose, an evaporation hose, or a breather hose, a water hose such as a radiator hose, a heater hose or a drain hose, or an air hose such as a turbo air hose or a vacuum brake hose. it can. And the said hose can be used for systems and equipment which require the function of these hoses, such as transport machines, such as a motor vehicle, a tractor, a cultivator, and a ship.

1 hose 2 cellulose short fiber

Claims (11)

  A hose comprising a rubber composition containing cellulose short fibers, wherein the cellulose short fibers are oriented parallel to the longitudinal direction of the hose.   The hose according to claim 1, wherein an average fiber length of the short cellulose fibers is in the range of 50 to 500 µm.   The hose according to claim 1 or 2, wherein the content ratio of the short cellulose fibers in the rubber composition is in the range of 3 to 120 parts by weight with respect to 100 parts by weight of the rubber component.   The rubber component in the rubber composition is at least selected from the group consisting of a blend polymer of acrylonitrile butadiene rubber and polyvinyl chloride (NBR-PVC), acrylonitrile butadiene rubber (NBR), and ethylene-propylene-diene rubber (EPDM). It is one, The hose as described in any one of Claims 1-3.   The hose according to any one of claims 1 to 4, further comprising the rubber composition containing a dehydrating agent.   The hose according to any one of claims 1 to 5, wherein the hose has a single-layer structure.   The hose according to any one of claims 1 to 6, wherein the hose is a curved pipe hose, and the outer wall thickness of the bent shape portion is formed to be thicker than the inner wall thickness.   It is a manufacturing method of the hose as described in any one of Claims 1-7, Comprising: The process of carrying out the hollow extrusion molding of the rubber composition containing a cellulose short fiber to a hose shape without using a mandrel, and vulcanizing | curing is provided. A method of manufacturing a hose characterized by   The method for producing a hose according to claim 8, wherein a rubber composition having a minimum torque value at a vulcanization temperature of 0.2 N · m or more is used as the rubber composition.   The method for producing a hose according to claim 8 or 9, wherein a rubber composition having a 10% vulcanization time of 0.1 to 7.0 minutes at the vulcanization temperature is used as the rubber composition.   The method for producing a hose according to any one of claims 8 to 10, wherein the rubber composition further containing a dehydrating agent is used as the rubber composition.

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