Method for manufacturing a brake hose

Abstract

Suppress a decrease in the adhesion between the reinforcing layer and the rubber layer of the brake hose. 【Solution means】A method for manufacturing a brake hose having an inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an outer rubber layer in this order from the inside, the method comprising: laminating an unvulcanized inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an unvulcanized outer rubber layer in this order from the inside; and subjecting the laminate to steam vulcanization at 115°C or higher and 140°C or lower and at a gauge pressure of 0.07 MPaG or higher and 0.26 MPaG or lower to bring the inner rubber layer and the outer rubber layer into a semi-vulcanized state in a first vulcanization step; and after the first vulcanization step, subjecting the laminate to vulcanization at 180°C or higher and 190°C or lower using hot air or warm air to completely vulcanize the inner rubber layer and the outer rubber layer in a second vulcanization step.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a brake hose.

Background Art

[0002] In vehicles such as automobiles, a hydraulic brake system that operates the brake by applying pressure to the brake fluid is widely adopted. In general, the transmission of hydraulic pressure to the brake is performed via a brake hose. Patent Document 1 discloses a hydraulic brake hose having an inner rubber layer, a first reinforcing yarn layer, a second reinforcing yarn layer, and an outer rubber layer in this order from the inside. Patent Document 1 discloses a brake hose in which the inner rubber layer is formed of an ethylene-propylene-diene rubber (EPDM) composition, the first reinforcing yarn layer and the second reinforcing yarn layer are formed of reinforcing yarns made of polyvinyl alcohol-based (hereinafter referred to as PVA), and the outer rubber layer is formed of an ethylene-propylene-diene rubber (EPDM) composition.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When each layer of the brake hose expands, the hydraulic pressure is not quickly transmitted to the brake, resulting in a decrease in the responsiveness of the brake. In addition, the brake hose tends to have a large expansion amount at high temperatures. Therefore, it is desired to improve the low expandability of each layer of the brake hose at high temperatures.

[0005] The inventors of the present application have found that in the brake hose disclosed in Patent Document 1, by using a reinforcing yarn containing polyethylene terephthalate (PET) instead of PVA as the material of the first reinforcing yarn layer and the second reinforcing yarn layer, the low expansibility at high temperatures can be improved. On the other hand, when using a reinforcing yarn containing PET, compared with the case of using a reinforcing yarn made of PVA disclosed in Patent Document 1, it has been found that the adhesiveness between the reinforcing yarn layer (the first reinforcing yarn layer, the second reinforcing yarn layer) and the rubber layer (the inner rubber layer, the outer rubber layer) adjacent thereto is low. When the adhesiveness between the reinforcing yarn layer and the rubber layer adjacent thereto is low, the performance of the hose tends to deteriorate. In particular, due to bending of the hose or the like, the rubber layer and the reinforcing yarn layer are likely to shift. When the rubber layer and the reinforcing yarn layer shift, cracks are likely to occur in the reinforcing yarn layer, and the durability may decrease.

[0006] By the way, in the manufacturing process of the brake hose as disclosed in Patent Document 1, the rubber layer (the inner rubber layer, the outer rubber layer) is vulcanized. When the rubber layer is vulcanized, the rubber layer and the adjacent reinforcing yarn layer adhere to each other. As vulcanization methods, there are methods of vulcanizing the rubber layer by immersing the hose in a heat medium such as oil, methods of vulcanizing the rubber layer with steam, and the like. In such methods, for the purpose of suppressing damage to the outer rubber layer during vulcanization and making the layers adhere closely to each other, the hose is coated with resin before vulcanization, the hose coated with resin is vulcanized, and the resin is removed from the hose after vulcanization. However, in recent years, there has been a demand for vulcanization without coating the resin from the viewpoint of treating the resin after use and the like.

[0007] When the inventors of the present application produced a brake hose in which the materials of the first reinforcing yarn layer and the second reinforcing yarn layer of the brake hose disclosed in Patent Document 1 were reinforcing yarns containing polyethylene terephthalate (PET) that improves low expansibility at high temperatures, the hose was vulcanized without coating the hose with resin. As a result, the obtained brake hose had low adhesiveness between the reinforcing yarn layer (first reinforcing yarn layer, second reinforcing yarn layer) and the rubber layer (inner rubber layer, outer rubber layer) adjacent thereto. Although the cause is not clear, in addition to using PET with low adhesiveness as the reinforcing yarn, vulcanization without coating with resin allowed the heat medium or steam to penetrate from the outermost layer to the inside during vulcanization, presumably reducing the adhesiveness.

[0008] An object of the present invention is to provide a method for manufacturing a brake hose with good adhesiveness between a rubber layer and a reinforcing layer even when using a reinforcing yarn containing polyethylene terephthalate (PET) with low adhesiveness to the rubber layer in the reinforcing layer of the brake hose and further vulcanizing the hose without coating it with resin.

Means for Solving the Problems

[0009] The method for manufacturing a brake hose disclosed in this specification is a method for manufacturing a brake hose having an inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an outer rubber layer in that order from the inside, and includes an unvulcanized inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an unvulcanized outer rubber layer in that order from the inside. Unvulcanized The laminate is subjected to steam vulcanization at 115°C or higher and 140°C or lower, and at a gauge pressure of 0.07 MPaG or higher and 0.26 MPaG or lower. For 7 to 10 minutes, while exposing the outer rubber layer By doing so, the inner rubber layer and the outer rubber layer are brought into a semi-vulcanized state. to obtain a semi-vulcanized laminate A first vulcanization step, and after the first vulcanization step, the Semi-vulcanized laminate is vulcanized at 180°C or higher and 190°C or lower using hot air or warm air. 、 By doing so, the inner rubber layer and the outer rubber layer are completely vulcanized. For 15 to 21 minutes, while exposing the outer rubber layer A second vulcanization step, and is provided with. to obtain a vulcanized laminate

[0010] ​Further, the inner rubber layer and the outer rubber layer may contain ethylene-propylene rubber.

[0011] Further, in the above manufacturing method, before vulcanizing the laminate in the first vulcanization step, Unvulcanized a mandrel is present inside the laminate, and in the first vulcanization step Unvulcanized the laminate is steam-vulcanized with the mandrel present in the laminate, and in the second vulcanization step, In this case the Unvulcanized laminate is vulcanized with the mandrel present in the laminate, and after the second vulcanization step, Unvulcanized a mandrel extraction step of extracting the mandrel from the laminate may be further provided. Semi-vulcanized the Semi-vulcanized laminate is vulcanized with the mandrel present in the laminate, and after the second vulcanization step, Vulcanized the mandrel is extracted from the laminate. Also, in the first vulcanization step, while the mandrel and the inner rubber layer are opposed to each other, the unvulcanized laminate may be steam-vulcanized, and in the second vulcanization step, while the mandrel and the inner rubber layer are opposed to each other, the semi-vulcanized laminate may be vulcanized using hot air or warm air. Also, after the first vulcanization step, the second vulcanization step may be carried out following the first vulcanization step.

Advantages of the Invention

[0012] To provide a method for manufacturing a brake hose in which a reinforcing yarn containing polyethylene terephthalate (PET) having low adhesiveness to a rubber layer is used for the reinforcing layer of the brake hose, and even when the hose is vulcanized without being coated with a resin, the adhesiveness between the rubber layer and the reinforcing layer is good.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described. Note that the embodiments described below are examples of embodying the present invention and do not limit the present invention.

[0015] The method according to this embodiment is a method for manufacturing a brake hose. The brake hose has an inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an outer rubber layer in this order from the inside. FIG. 1 shows an example of a brake hose.

[0016] The brake hose 100 shown in FIG. 1 has an inner rubber layer 1, a first reinforcing layer (reinforcing layer) 2, an intermediate rubber layer 3, a second reinforcing layer (reinforcing layer) 4, and an outer rubber layer 5 in this order from the inside. These are cylindrical. The brake hose 100 is used, for example, as a brake hose for a vehicle.

[0017] The inner rubber layer 1 is the innermost layer of the brake hose 100. The inner rubber layer 1 contains ethylene-propylene rubber. Examples of ethylene-propylene rubber include ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber (EPDM). The inner rubber layer 1 may contain one type of ethylene-propylene rubber or two or more types of ethylene-propylene rubber. Further, the inner rubber layer 1 may contain materials other than ethylene-propylene rubber. The inner rubber layer 1 is obtained, for example, by extrusion molding or the like.

[0018] The first reinforcing layer 2 is formed of reinforcing yarns containing polyethylene terephthalate (PET). The reinforcing yarns may contain materials other than PET. Examples of materials other than PET include, for example, polyvinyl alcohol (PVA)-based fibers, polyester-based fibers, polyamide-based fibers, aramid-based fibers, glass fibers, metal fibers, and the like. The first reinforcing layer 2 is formed by winding and knitting the reinforcing yarns around the inner rubber layer 1. The knitting method is not particularly limited, and examples include spiral knitting, blade knitting, and the like.

[0019] The intermediate rubber layer 3 is a layer between the first reinforcing layer 2 and the second reinforcing layer 4. The intermediate rubber layer 3 contains ethylene-propylene rubber, butyl rubber, or a combination of these rubbers. Examples of ethylene-propylene rubber are the same as those described for the inner rubber layer 1. The intermediate rubber layer 3 may contain one type of ethylene-propylene rubber or two or more types of ethylene-propylene rubber. Examples of butyl rubber include butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and the like. The intermediate rubber layer 3 may contain one type of butyl rubber or two or more types of butyl rubber. The intermediate rubber layer 3 may contain materials other than ethylene-propylene rubber and butyl rubber. The intermediate rubber layer 3 is obtained, for example, by coating by extrusion molding or the like.

[0020] The second reinforcing layer 4 is formed of reinforcing yarns containing polyethylene terephthalate (PET). The reinforcing yarns may contain materials other than PET. Examples of materials other than PET include, for example, polyvinyl alcohol (PVA)-based fibers, polyester-based fibers, polyamide-based fibers, aramid-based fibers, glass fibers, metal fibers, and the like. The second reinforcing layer 4 is formed by winding and knitting the reinforcing yarns around the intermediate rubber layer 3. The knitting method is not particularly limited, and examples include spiral knitting, blade knitting, and the like.

[0021] The outer rubber layer 5 is the outermost layer of the brake hose 100. The outer rubber layer 5 contains ethylene-propylene rubber. Examples of ethylene-propylene rubber are the same as those described for the inner rubber layer 1. The inner rubber layer 1 may contain one type of ethylene-propylene rubber or two or more types of ethylene-propylene rubber. The outer rubber layer 5 may contain materials other than ethylene-propylene rubber. For example, the outer rubber layer 5 may contain, in addition to ethylene-propylene rubber, one or two or more of chloroprene rubber (CR), isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), halogenated butyl rubber, and acrylonitrile-butadiene copolymer rubber (NBR). The outer rubber layer 5 is obtained, for example, by extrusion molding or the like.

[0022] In the brake hose 100 shown in FIG. 1, there is an intermediate rubber layer 3 between the first reinforcing layer 2 and the second reinforcing layer 4, but a brake hose without the intermediate rubber layer 3 may also be used. Also, when the intermediate rubber layer 3 does not exist, two reinforcing layers (the first reinforcing layer 2 and the second reinforcing layer 4) may exist between the inner rubber layer 1 and the outer rubber layer 5, or only one reinforcing layer may exist.

[0023] Next, a method for manufacturing the brake hose will be described. Here, the description will be made using the reference numerals of the brake hose 100 shown in FIG. 1.

[0024] FIG. 2 shows an example of an apparatus used for manufacturing the brake hose.

[0025] The first vulcanizing apparatus 20 shown in FIG. 2 is an apparatus for steam-vulcanizing an object. The first vulcanizing apparatus 20 has a first vulcanizing tube 21, a second vulcanizing tube 22, and a direction switching device 23. The first vulcanizing tube 21 and the second vulcanizing tube 22 are long in one direction. One end of the first vulcanizing tube 21 and one end of the second vulcanizing tube 22 are connected to the direction switching device 23. The direction switching device 23 is a device that changes the traveling direction of the object so that the object that has passed through the first vulcanizing tube 21 enters the second vulcanizing tube 22.

[0026] The interiors of the first vulcanization tube 21 and the second vulcanization tube 22 are filled with steam. Due to the steam, the interiors of the first vulcanization tube 21 and the second vulcanization tube 22 are at a temperature of 115°C or higher and 140°C or lower, and a gauge pressure of 0.07 MPaG or higher and 0.26 MPaG or lower. It is more preferable that the interiors of the first vulcanization tube 21 and the second vulcanization tube 22 are at a temperature of 130°C or higher and 140°C or lower, and it is more preferable that the gauge pressure is 0.17 MPaG or higher and 0.26 MPaG or lower. The first vulcanization tube 21 and the second vulcanization tube 22 are used to steam-vulcanize the object.

[0027] Note that the interior of the direction switching device 23 may also be at the same temperature and pressure as the interiors of the first vulcanization tube 21 and the second vulcanization tube 22 by steam. For example, the interior of the direction switching device 23 may be at a temperature of 115°C or higher and 140°C or lower, and a gauge pressure of 0.07 MPaG or higher and 0.26 MPaG or lower by steam.

[0028] The second vulcanization device 30 shown in FIG. 2 is a device for vulcanizing an object by hot air or warm air. The interior of the second vulcanization device 30 is at a temperature of 180°C or higher and 190°C or lower by hot air or warm air. It is more preferable that the interior of the second vulcanization device 30 is at a temperature of 183°C or higher and 188°C or lower. The second vulcanization device 30 is, for example, an oven.

[0029] Hereinafter, a method for manufacturing the brake hose 100 shown in FIG. 1 using the first vulcanization device 20 and the second vulcanization device 30 shown in FIG. 2 will be described.

[0030] The laminate 110 shown in FIG. 2 has an unvulcanized inner rubber layer 1, a first reinforcing layer 2, an unvulcanized intermediate rubber layer 3, a second reinforcing layer 4, and an unvulcanized outer rubber layer 5 in this order from the inside. is an unvulcanized laminate . There is a mandrel 10 inside the laminate 110. The mandrel 10 is used when manufacturing the laminate 110. For example, after extruding the unvulcanized inner rubber layer 1 onto the outer peripheral surface of the mandrel 10 and braiding reinforcing yarns on the outer peripheral surface of the inner rubber layer 1 to form the first reinforcing layer 2, the unvulcanized intermediate rubber layer 3 is coated on the outer peripheral surface of the first reinforcing layer 2. After forming the second reinforcing layer 4 by braiding reinforcing yarns on the outer peripheral surface of the intermediate rubber layer 3,The second reinforcing layer 4 Extrude the unvulcanized outer surface rubber layer 5 onto the outer peripheral surface of The second reinforcing layer 4 . The laminate 110 is not coated with resin or the like.

[0031] With the mandrel 10 present in the laminate 110, place the laminate 110 into the first vulcanization tube 21. In the conventional vulcanization method, the laminate 110 is coated with resin, and the resin-coated laminate 110 is placed into the first vulcanization tube 21. However, in this embodiment, the laminate 110 is not coated with resin before vulcanization. Place the laminate 110 that is not coated with resin into the first vulcanization tube 21.

[0032] While the laminate 110 is passing through the first vulcanization tube 21, the inner surface rubber layer 1, the intermediate rubber layer 3, and the outer surface rubber layer 5 are vulcanized. The laminate 110 that has passed through the first vulcanization tube 21 enters the direction switching device 23, changes its traveling direction, and enters the second vulcanization tube 22. If the inside of the direction switching device 23 has the same temperature and pressure as the inside of the first vulcanization tube 21 and the inside of the second vulcanization tube 22 due to steam, the laminate 110 is also vulcanized within the direction switching device 23. Thereafter, the laminate 110 passes through the second vulcanization tube 22. While the laminate 110 is passing through the second vulcanization tube 22, the inner surface rubber layer 1, the intermediate rubber layer 3, and the outer surface rubber layer 5 are vulcanized. The lengths of the first vulcanization tube 21 and the second vulcanization tube 22 are, for example, 140 to 150 m. The traveling speed of the laminate 110 inside the tube is, for example, 15 to 20 m / min. The laminate 110 is vulcanized in the first vulcanization device 20 for, for example, 7 to 10 minutes.

[0033] The laminate that has come out of the second vulcanization tube 22 The object is , the inner surface rubber layer 1, the intermediate rubber layer 3, and the outer surface rubber layer 5 are in a semi-vulcanized state Semi-vulcanized laminate . "The inner surface rubber layer 1, the intermediate rubber layer 3, and the outer surface rubber layer 5 are in a semi-vulcanized state" means that the rubber contained in the inner surface rubber layer 1, the rubber contained in the intermediate rubber layer 3, and the rubber contained in the outer surface rubber layer 5 are in a semi-vulcanized state. "The rubber is in a semi-vulcanized state" means that the rubber is not in an unvulcanized state and is not completely vulcanized, indicating a state between the unvulcanized state and the completely vulcanized state of the rubber.

[0034] Thus, the first vulcanization device 20 makes the laminate 110 (Unvulcanized laminate) into a semi-vulcanized state of the laminate (semi-vulcanized laminate) (first vulcanization step).

[0035] Subsequently, the semi-vulcanized laminate (Semi-vulcanized laminate) is completely vulcanized by the second vulcanization device 30 (second vulcanization step). By completely vulcanizing the inner rubber layer 1, the intermediate rubber layer 3, and the outer rubber layer 5, the laminated The object is brake hose 100 is formed. Here, "completely vulcanizing the inner rubber layer 1, the intermediate rubber layer 3, and the outer rubber layer 5" means completely vulcanizing the rubber contained in the inner rubber layer 1, the rubber contained in the intermediate rubber layer 3, and the rubber contained in the outer rubber layer 5. In the second vulcanization device 30, for example, the laminate The object is is vulcanized for 15 to 21 minutes.

[0036] After completely vulcanizing the inner rubber layer 1, the intermediate rubber layer 3, and the outer rubber layer 5, the brake hose 100 is taken out from the second vulcanization device 30, and the mandrel 10 is removed from the brake hose 100 (mandrel removal step).

[0037] According to the above method, the following effects can be obtained. The first reinforcing layer 2 and the second reinforcing layer 4 shown in FIG. 1 use reinforcing yarns containing polyethylene terephthalate (PET) with low adhesiveness to the inner rubber layer 1, the intermediate rubber layer 3, and the outer rubber layer 5. Also, in the above method, the laminate 110 is vulcanized without being coated with resin. Although conditions are in place that tend to reduce the adhesiveness between such rubber layers (inner rubber layer 1, intermediate rubber layer 3, outer rubber layer 5) and the reinforcing layers (first reinforcing layer 2, second reinforcing layer 4), by vulcanizing the laminate 110 in two stages under the above vulcanization conditions, a brake hose 100 with good adhesiveness between the rubber layers (inner rubber layer 1, intermediate rubber layer 3, outer rubber layer 5) and the reinforcing layers (first reinforcing layer 2, second reinforcing layer 4) can be manufactured.

[0038] When vulcanizing fluororubber, silicone rubber, or rubber that is difficult to vulcanize, for example, two vulcanization steps such as primary vulcanization and secondary vulcanization are required. However, for rubbers other than these, it is common to vulcanize the rubber in a single vulcanization step without performing two vulcanization steps. This is because if two vulcanization steps are performed on such rubbers, the temperature of the hose may vary, which may cause the vulcanization state to become unstable. In the present embodiment, instead of using rubbers that require two vulcanization steps for the inner rubber layer 1, the intermediate rubber layer 3, and the outer rubber layer 5, a rubber layer using a rubber that is normally vulcanized in a single vulcanization step is used. For example, a case where ethylene-propylene rubber or the like is used for the rubber layer. In such a case, it has been found that by vulcanizing the laminate 110 in two stages under the above vulcanization conditions, the rubber layers (inner rubber layer 1, intermediate rubber layer 3, outer rubber layer 5) can be brought into a vulcanization state equivalent to that in the case of normal single vulcanization.

[0039] Also, in the above embodiment, as shown in FIG. 2, the laminate 110 is vulcanized with the mandrel 10 present in the laminate 110. Thereby, the shape of the hose can be maintained even during vulcanization. In particular, in the first vulcanizing device 20, since the pressure is high, the shape of the laminate 110 is likely to collapse. Also, due to the influence of steam, hot air, or warm air, the shape of the laminate 110 is likely to collapse. However, since the mandrel 10 allows the laminate 110 to be vulcanized while maintaining the hose shape, a brake hose 100 having a hose shape can be obtained.

[0040] On the other hand, since the mandrel 10 is present inside the inner rubber layer 1, the inner inner rubber layer 1 and the intermediate rubber layer 3 are difficult to be vulcanized. However, in the present embodiment, since rubbers that require two vulcanization steps are not used, even when the laminate 110 is vulcanized with the mandrel 10 present, all the rubber layers including the inner rubber layer 1, the intermediate rubber layer 3, and the outer rubber layer 5 can be completely vulcanized, and a brake hose 100 with the hose shape maintained can be obtained.

[0041] Next, the experiment in which the above findings were obtained will be described.

[0042] (Experiment 1) In the method for manufacturing a brake hose described in the above embodiment, the brake hose was manufactured by changing the temperature conditions and pressure conditions in the first vulcanization step. Table 1 shows the temperature conditions and pressure conditions in the first vulcanization step. The conditions shown in Table 1 are the conditions under which all rubber layers could be semi-vulcanized in the first vulcanization step. In the first vulcanization step, two vulcanization tubes of 70 to 75 m were used, and the traveling speed of the laminate in the vulcanization tube was set to 15 to 20 m / min. In the second vulcanization step, the inside of the apparatus was heated to 180°C to 190°C by hot air, and the laminate was vulcanized for 15 to 21 minutes.

[0043] In this experiment, the first vulcanization step and the second vulcanization step were carried out with the mandrel present in the laminate. After the second vulcanization step, the mandrel was removed from the brake hose.

[0044] [Table 1]

[0045] In order to examine the adhesiveness between the rubber layer and the reinforcing layer, the outer rubber layer of the manufactured brake hose was peeled off. The force required to peel off 1 cm of the outer rubber layer was defined as the adhesive force [N / cm]. From previous experience, it has been found that when the adhesive force is 35 N / cm or more, the rubber layer and the reinforcing layer are less likely to shift even when the hose is bent. Therefore, when the adhesive force is 35 N / cm or more, it is determined that the adhesiveness is high, and it is indicated as "〇" in Table 2. In addition, when the adhesive force is less than 35 N / cm but 30 N / cm or more, the rubber layer and the reinforcing layer are less likely to shift, but in Table 1, it is indicated as "△". When the adhesive force is less than 30 N / cm, it is indicated as "×" in Table 1. Table 1 shows the determination results. Also, Fig. 3 shows the relationship between the adhesive force and the vulcanization pressure. The vulcanization pressure shown in Fig. 3 is the vulcanization pressure in the first vulcanization step.

[0046] From Table 1 and FIG. 3, it was found that when the vulcanization temperature in the first vulcanization step is 115°C or higher and 140°C or lower, and the vulcanization pressure is 0.07 MPaG or higher and 0.26 MPaG or lower in gauge pressure, the adhesiveness between the rubber layer and the reinforcing layer adjacent thereto is high.

[0047] (Experiment 2) In the method for manufacturing a brake hose described in the above embodiment, the brake hose was manufactured by changing the vulcanization temperature in the second vulcanization step. Table 2 shows the temperature conditions in the second vulcanization step. The vulcanization time in the second vulcanization step is 15 to 21 minutes.

[0048] In the first vulcanization step, the laminate was vulcanized with the vulcanization temperature being 115°C or higher and 140°C or lower, and the vulcanization pressure being 0.07 MPaG or higher and 0.26 MPaG or lower in gauge pressure. Also, two vulcanization tubes of 70 to 75 m were used, and the traveling speed of the laminate in the vulcanization tube was 15 to 20 m / min. In this experiment as well, the laminate was vulcanized with the mandrel present in the laminate. After the second vulcanization step, the mandrel was removed from the brake hose.

[0049]

Table 2

[0050] To examine the vulcanization state of the rubber layer, the outer rubber layer sampled from the manufactured brake hose was pulled in the axial direction of the brake hose, and the force when the outer rubber layer was stretched 100% was defined as the 100% modulus [N]. Similarly, the inner rubber layer sampled from the manufactured brake hose was pulled in the axial direction of the brake hose, and the force when the inner rubber layer was stretched 100% was defined as the 100% modulus [N]. Table 2 shows the 100% moduli [N] of the outer rubber layer and the inner rubber layer. FIG. 4 shows the relationship between the 100% modulus [N] of the outer rubber layer and the vulcanization temperature. FIG. 5 shows the relationship between the 100% modulus [N] of the inner rubber layer and the vulcanization temperature. The vulcanization temperatures shown in FIGS. 4 and 5 are the vulcanization temperatures in the second vulcanization step.

[0051] Table 2, FIGS. 4 and 5 show, for comparison, the 100% moduli [N] of the outer rubber layer and the inner rubber layer of three types of brake hoses manufactured by a conventional vulcanization method. The conventional vulcanization method is a method of coating a laminate with a resin before vulcanization and subjecting the resin-coated laminate to steam vulcanization. The range of the 100% modulus [N] of the outer rubber layer of these three types of brake hoses was 35 N or more and 42 N or less, and the range of the 100% modulus [N] of the inner rubber layer was 67 N or more and 75 N or less. If the 100% modulus [N] is within the range of the 100% moduli [N] of these three types, it can be said that the rubber layer is in a vulcanized state comparable to that in the case of implementing the conventional vulcanization method.

[0052] From Table 2 and FIG. 4, it was found that when the vulcanization temperature in the second vulcanization step was 180°C or more and 190°C or less, the 100% modulus [N] of the outer rubber layer was within the range of the 100% modulus [N] of the conventional vulcanization method. Also, from Table 2 and FIG. 5, it was found that when the vulcanization temperature in the second vulcanization step was 180°C or more and 190°C or less, the 100% modulus [N] of the inner rubber layer was within the range of the 100% modulus [N] of the conventional vulcanization method. From this, it was found that by vulcanizing the laminate at 180°C or more and 190°C or less in the second vulcanization step after the first vulcanization step, a vulcanized state equivalent to that in the case of implementing the conventional vulcanization method can be achieved.

[0053] From the above, a laminate having an inner rubber layer, a reinforcing layer containing polyethylene terephthalate (PET), and an outer rubber layer in this order from the inside is steam-vulcanized in the first vulcanization step at 115°C or more and 140°C or less and a gauge pressure of 0.07 MPaG or more and 0.26 MPaG or less, and in the second vulcanization step, vulcanized at 180°C or more and 190°C or less using hot air or warm air. It was found that even when the hose is vulcanized without being coated with a resin, a brake hose with high adhesiveness equivalent to that of a brake hose manufactured by the conventional vulcanization method can be manufactured. Also, it was found that even when a reinforcing yarn containing PET with low adhesiveness to the rubber layer is used for the reinforcing layer, a brake hose with high adhesiveness between the rubber layer and the reinforcing layer can be manufactured.

[0054] As described above, the embodiments of the present invention have been described with reference to the drawings. However, the specific configuration should be considered not to be limited to these embodiments. The scope of the present invention is shown not by the above description but by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

[0055] For example, in the above embodiments and experiments, as shown in FIG. 2, the laminate 110 was vulcanized with the mandrel 10 present in the laminate 110. However, the laminate 110 may be vulcanized without the mandrel 10 being present in the laminate 110.

Explanation of Reference Numerals

[0056] 1 Inner rubber layer 2 First reinforcing layer (reinforcing layer) 3 Intermediate rubber layer 4 Second reinforcing layer (reinforcing layer) 5 Outer rubber layer 10 Mandrel 20 First vulcanizing device 21 First vulcanizing pipe 22 Second vulcanizing pipe 23 Direction switching device 30 Second vulcanizing device 100 Brake hose 110 Laminate

Claims

1. A method for manufacturing a brake hose having an inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an outer rubber layer in this order from the inside, comprising the steps of: a first vulcanization step of steam vulcanizing an unvulcanized laminate having, from the inside, an unvulcanized inner rubber layer, a reinforcing layer containing polyethylene terephthalate, and an unvulcanized outer rubber layer at 115° C. or higher and 140° C. or lower at a gauge pressure of 0.07 MPaG or higher and 0.26 MPaG or lower for 7 to 10 minutes while exposing the outer rubber layer, thereby obtaining a semi-vulcanized laminate in which the inner rubber layer and the outer rubber layer are in a semi-vulcanized state; a second vulcanization step of vulcanizing the semi-vulcanized laminate by using hot or warm air at 180° C. or more and 190° C. or less for 15 to 21 minutes while exposing the outer rubber layer to the outside, thereby obtaining a vulcanized laminate in which the inner rubber layer and the outer rubber layer are completely vulcanized; A method for manufacturing a brake hose, comprising:

2. The inner rubber layer and the outer rubber layer contain ethylene propylene rubber. The method for manufacturing a brake hose according to claim 1 .

3. Before vulcanizing the unvulcanized laminate in the first vulcanization step, a mandrel is present inside the unvulcanized laminate, In the first vulcanization step, the unvulcanized laminate is vulcanized by steam in a state where the mandrel is present in the unvulcanized laminate; In the second vulcanization step, the semi-vulcanized laminate is vulcanized in the presence of the mandrel, The method further includes a mandrel removal step of removing the mandrel from the vulcanized laminate after the second vulcanization step.

3. The method for manufacturing a brake hose according to claim 1 or 2.

4. In the first vulcanization step, the unvulcanized laminate is vulcanized by steam vulcanization with the mandrel and the inner rubber layer facing each other; In the second vulcanization step, the semi-vulcanized laminate is vulcanized using hot air or warm air with the mandrel and the inner rubber layer facing each other. The method for manufacturing a brake hose according to claim 3 .

5. After the first vulcanization step, the second vulcanization step is carried out following the first vulcanization step.

3. The method for manufacturing a brake hose according to claim 1 or 2.

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