JPH0649029U - Fiber reinforced rubber hose - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a well-balanced fiber-reinforced rubber hose that has excellent heat resistance, cold resistance, compression set resistance, and oil resistance, as well as excellent sealability, insertability, and yield. The purpose is to A reinforcing rubber hose comprising an inner coat layer, a fiber reinforcing layer and an outer coat layer, wherein the inner coat layer and / or the outer coat layer is a carboxyl group-containing acrylic copolymer elastomer and a carboxyl group-containing ethylene-acrylate copolymer elastomer. Was formed of a rubber composition blended at a ratio of 10 to 30% by weight, and the fiber reinforcing layer was formed of aromatic polyamide fibers.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rubber hose having a fiber reinforced layer interposed between an inner cover layer and an outer cover layer, and more specifically, supplies or discharges oil such as engine oil, PSF, ATF, or air containing these. The present invention relates to an oil-based hose for automobiles, a radiator hose, etc., and various fiber-reinforced rubber hoses for hydraulic pressure used at low pressure.

[0002]

[Prior art]

 Conventionally, flexible rubber hoses used as automobile parts such as engine oil cooler hoses, return hoses for power steering oils, hoses for automatic transmissions (torque converter hoses), etc. are required to have high performance. Is coming. In other words, in addition to heat resistance, oil resistance, etc., due to the effects of the recent increase in temperature in the engine room of automobiles, the upgrading of oil to higher grades due to these temperatures, and the acceleration of oil deterioration Balanced qualities such as sealing properties are more strict than ever before.

Here, the sealing property refers to the ability to prevent the medium used from seeping or leaking from between the rubber hose and the nipple when the rubber hose is inserted into a pipe or a nipple and a clip is attached to the outside. . Therefore, the seal property in this invention excludes the structure in which the rubber hose is inserted between the nipple and the sleeve to crimp the sleeve. Of the rubber hoses for automobiles, low pressure rubber hoses with relatively low operating pressure are targeted. For the inner layer and / or outer layer of such a conventional rubber hose, NBR or an acrylic copolymer elastomer, and further an ethylene-acrylate copolymer elastomer have been conventionally used. Further, vinylon yarn or nylon yarn is generally used for the fiber reinforcing layer.

[0004]

[Problems to be Solved by the Invention] However, the fiber-reinforced rubber hose having the above structure has the following problems. That is, although the acrylic copolymer elastomer is excellent in heat resistance and oil resistance, it has problems in cold resistance, kneading and extrusion processability. In particular, the epoxy group-containing acrylic copolymer has a long vulcanization time, Poor mechanical strength. On the other hand, the active chlorine group-containing acrylic copolymer is excellent in vulcanization characteristics and mechanical strength, but has problems such as deterioration of the fiber reinforcing layer. Further, although the ethylene-acrylate copolymer elastomer is excellent in heat resistance, cold resistance and extrusion processability, contrary to the above-mentioned acrylic copolymer elastomer, it has a problem of poor oil resistance. Thus, it was not possible to obtain a balanced quality.

Further, the vinylon yarn or the nylon yarn used for the fiber reinforcing layer has the following problems. That is, there is a problem that the reinforcing yarn is inferior in sealing property between the metal fitting and the rubber hose, and is greatly deteriorated due to the heat shrinkage and the effect of the rubber additive. The factors that deteriorate the sealability are that the inner diameter of the rubber hose is large relative to the outer diameter of the nipple, and the outer diameter of the hose changes (expansion rate) when pressure is applied to the inside of the hose. Is an uneven surface and is not smooth, and the like. Therefore, in order to improve the sealing property, the above factors may be removed. However, if the above factors are to be removed, the following problems will occur.

That is, if the inner diameter of the hose is reduced from the first factor, the force of inserting the hose into the nipple is increased and the workability of assembling the hose is deteriorated. In the work of assembling a hose on an automobile assembly line, the hose insertion force is required to be 8 kgf or less, preferably 6 kgf or less. Further, from the second factor, it is considered that the amount of yarn in the fiber reinforcing layer is increased in order to suppress the change in the outer diameter of the hose. That is, the yarn amount per unit area may be increased. However, if the amount of yarn is increased, the flexibility of the rubber hose deteriorates, so that the performance of the rubber hose, which connects the parts and absorbs the vibration between the phases, is deteriorated. Furthermore, as the amount of yarn increases, not only does the cost increase, but the anchoring effect of rubber on the reinforcing layer decreases, and the adhesion between the rubber layer and the reinforcing layer (interlayer adhesion) deteriorates. .

Further, for the third factor, the hose inner surface and outer surface may be formed to be smooth. It is considered that the unevenness of the inner and outer surfaces of the hose is due to the heat shrinkability of the reinforcing yarn forming the fiber reinforcing layer. The heat shrinkage of the reinforcing yarn increases the variation in the inner and outer diameters of the rubber hose and deteriorates the sealing property due to the formation of the uneven surface. That is, there is always a vulcanization step in the manufacturing process of the rubber hose, and the vulcanization temperature thereof is usually 150 ° C to 200 ° C. Therefore, the conventionally used reinforcing yarn shrinks greatly and causes irregularities called yarns on the inner and outer surfaces of the hose. In particular, when the reinforcing yarn is roughly wound or braided, the uneven surface is conspicuous. When the uneven surface is formed, when the clip is inserted into the nipple and the clip is assembled, the surface pressure on the nipple is not constant and the sealing property is naturally deteriorated. When the reinforcing yarn is wound in a spiral shape, a concave surface is formed in a spiral shape on the inner surface and the outer surface of the hose. The medium used leaks through the spiral concave surface.

In order to prevent the sealing property from being deteriorated due to the heat shrinkage of the reinforcing yarn, a reinforcing yarn subjected to a low shrinkage treatment may be used. However, conventionally used nylon yarns have improved heat shrinkage, but have a higher intermediate elongation. As a result, the rate of change in outer diameter during pressurization increases, and the sealability decreases. Further, vinylon fiber (PVA) has poor heat resistance, and when used in a curved hose such as the hose, there is a problem that the vinylon fiber exposed at the end is dissolved by vulcanization heat or steam.

Further, when a reinforcing yarn having a large heat shrinkage is used for a bent hose, there is a problem that the yield is low. In other words, after vulcanization and molding, the ratio of the parts that are cut off at both ends and discarded in order to obtain a predetermined product shape is extremely large. Many bent hoses are vulcanized and molded by inserting bent iron cores of a specified shape, but if reinforcing yarn with a high heat shrinkage is used, the unvulcanized rubber hose must be inserted long in anticipation of the shrinkage. In particular, the shrinkage rate in the straight line area becomes large, and the heat shrinkage rate changes due to the difference in the bent shape. In order to solve such a problem, a reinforcing yarn subjected to a low shrinkage treatment may be used, but the shrinkage cannot be sufficiently prevented.

The present invention has been made in view of the present situation, and is excellent in heat resistance, cold resistance, compression set resistance, and oil resistance, and is also excellent in sealing property, insertability, and yield. An object of the present invention is to provide a fiber reinforced rubber hose.

[0011]

[Means for Solving the Problems]

 The present invention has the following configuration in order to achieve the above object. That is, in a reinforced rubber hose comprising an inner coat layer, a fiber reinforcing layer and an outer coat layer, the inner coat layer and / or the outer coat layer is a carboxyl group-containing acrylic copolymer elastomer and a carboxyl group containing ethylene-acrylate copolymer elastomer. Was blended to form a rubber composition having a blending ratio of the carboxyl group-containing ethylene-acrylate copolymer elastomer of 10 to 30% by weight, and the fiber reinforcing layer was formed of an aromatic polyamide fiber.

The carboxyl group-containing acrylic copolymer elastomer in the present invention includes, for example, a carboxyl group-containing acrylic copolymer elastomer obtained by copolymerizing a carboxyl group-containing monomer, and a carboxyl group-containing ethylene-vinyl acetate. A copolymer elastomer may be used. The carboxyl group-containing acrylic copolymer elastomer can be produced by a conventionally known method for copolymerizing an acrylic copolymer elastomer, for example, suspension polymerization method or emulsion polymerization method.

As the carboxyl group-containing acrylic elastomer, an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, n- or iso-propyl acrylate is used as the alkyl acrylate, and particularly ethyl acrylate and N-butyl acrylate is preferred. As the carboxyl group-containing monomer, for example, acrylic acid, methacrylic acid, vinyl acetic acid, maleic acid and the like are used, and among them, acrylic acid, methacrylic acid, maleic acid monoalkyl ester and cinnamic acid are preferable. One or more of these carboxyl group-containing monomers are used in a proportion of about 20 to 0.1% by weight of the total copolymer as a whole. Such a carboxyl group-containing acrylic copolymer elastomer has improved vulcanizability and is superior to conventional active chlorine group- or epoxy group-containing acrylic copolymers in the balance of properties such as compression set and cold resistance. It is a material.

Further, the carboxyl group-containing ethylene-acrylate copolymer elastomer can be produced by a conventionally known high-pressure polymerization method. The carboxyl group-containing ethylene / acrylate copolymer elastomer is described in, for example, US Pat. No. 3,850,872, and is a material excellent in cold resistance, heat resistance, and processability as compared with conventional acrylic copolymer elastomers. .

A rubber composition according to the present invention comprises a rubber composition having a carboxyl group-containing acrylic copolymer elastomer and a carboxyl group-containing ethylene-acrylate copolymer elastomer, and having excellent characteristics of both. It is characterized by having done. The blending ratio was 10 to 30% by weight of the carboxyl group-containing ethylene-acrylate copolymer elastomer. When the blending ratio is 10% by weight or less, the extrusion processability, particularly the extrusion speed, is slow, the extruded surface becomes poor, and the kneading processability is also poor. On the other hand, if the blending ratio is 30% by weight or more, oil resistance, compression set, mechanical strength, and shape retention due to heat during molding deteriorate.

Further, the fiber reinforcing layer interposed between the inner coating layer and the outer coating layer is formed of an aromatic polyamide fiber. The inventors of the present invention have made intensive efforts to develop the solution to the problems of the invention, and the aromatic polyamide fiber has high strength and does not shrink due to vulcanization temperature. I found that there is. That is, by using an aromatic polyamide fiber having a small intermediate elongation, it is possible to suppress a change in the outer diameter of the rubber hose when an internal pressure is applied to the rubber hose, and as a result, a fiber reinforced rubber hose having excellent sealing properties. I was able to get The aromatic polyamide fiber may be either para-based or meta-based. Examples of the para-aromatic polyamide fiber include polyparaphenylene terephthalamide (PPTA) and copolyparaphenylene.3.4 'oxydiphenylene terephthalamide, and the like, and the meta-aromatic polyamide fiber is polymeta Examples include phenylene isophthalamide.

[0017]

[Function of the device]

 By blending the carboxyl group-containing acrylic copolymer elastomer with the carboxyl group-containing ethylene-acrylate copolymer elastomer in an amount of 10 to 30% by weight, the extrusion processability and kneading processability could be improved. In addition, the aromatic polyamide fiber does not heat-shrink at the temperature during vulcanization and has a small intermediate elongation. Therefore, the inner and outer surfaces of the hose were smooth, and the change in outer diameter when pressure was applied to the inside of the hose was small, and a rubber hose excellent in sealability and insertability was obtained.

[0018]

【Example】

 Hereinafter, the present invention will be described in detail based on embodiments. First, the blend ratio of the carboxyl group-containing acrylic copolymer elastomer and the carboxyl group-containing ethylene-acrylate copolymer elastomer will be described. In the examples, KNOXTITE (trade name) manufactured by Nippon Mektron Co., Ltd. was used as the acrylic copolymer elastomer containing a carboxyl group, and Vemac (trade name) manufactured by DuPont was used as an ethylene-acrylate copolymer elastomer containing a carboxyl group. It was used. The results obtained are shown in Table 1.

[0019]

[Table 1]

In Table 1, the extrusion processability and the hose crushability are obtained by using a plastic coder manufactured by Brabender as an extruder, L / D = 10/1, die temperature 90 ° C., barrel temperature 70 ° C., screw rotation speed. Extrusion was carried out under the condition of 30 rpm, and the extrudability was evaluated on a comprehensive scale of 5 grades: surface texture at the time of extrusion, edge shape retention, and extrusion speed. The larger the number, the better, 5 is excellent, 4 is good, 3 is normal, 2 is acceptable, and 1 is not acceptable. The hose crushability was evaluated by using the plastic coder and measuring the crush after a tube having an inner diameter of 10 mm and an outer diameter of 12 mm extruded by a tubing die for 20 minutes in an oven at 150 ° C. The kneading workability was evaluated on the basis of a total of 5 grades, namely, the tackiness of the material on the roll surface when the material was kneaded with an 8-inch roll (all water cooled), the hardness of the kneading material, and the workability. The evaluation method is the same as that for extrusion processability. The viscosity is an evaluation when a tester manufactured by Monsanto Corporation (MONSANTO Processability Tester) is used and extruded at 90 ° C. and a shear rate of 200 sec ⁻¹ . Furthermore, the methods for measuring hardness (JIS-A), tensile strength at break, elongation at break, compression set, and rate of change in volume were measured according to JIS K6301.

As is clear from the above results, the higher the blending ratio of the carboxyl group-containing ethylene-acrylate copolymer elastomer is, the better the extrusion processability is, but the kneading processability and the hose crushability are deteriorated. As shown in Examples 3 to 5, kneading workability and hose crushability were improved when the blending ratio was 10 to 30% by weight.

Next, examples of sealing and insertability will be shown. As for the sealing property, as shown in FIG. 1, one end was connected to the hydraulic pump 10 side, the other end was fitted with a nipple 11 and fixed with a plate clip 12. For the nipple 11, a JASO M101-75 "metal tube for automobile piping" bulge type nominal diameter 8 was used. Water is used as the medium, and the pressure is increased step by step by 1 kgf / cm ² (0.0981 MPa), and the pressure at the time when water seeps or leaks between the hose and the nipple, or when the nipple comes off It was evaluated by pressure. The obtained results are shown in Table 2.

[0023]

[Table 2]

As is clear from Table 2 above, it is understood that the example is superior to the comparative example in both the sealability and the insertability. The rate of change in the outer diameter of the hose when pressurized at 1 MPa was also extremely low in the examples, indicating that the intermediate elongation of the reinforcing yarn was small. Conventionally, the sealing property has been mainly considered in a high-pressure rubber hose using a joint fitting having a sleeve, and therefore, the low-pressure rubber hose is also held by a tightening force of a leaf spring clip or the like. However, the tightening force of the leaf spring clip is limited, and it was not possible to satisfy the sufficient sealing performance. Therefore, in this invention, we focused on the reinforcing yarn to be interposed in the rubber layer, and decided to use aromatic polyamide fiber that does not shrink heat at the temperature during vulcanization and has a small intermediate elongation.

Further, the yield due to the change in the thermal contraction rate of the bent hose was examined. The yield here is the ratio of the part that is cut and discarded at both ends after vulcanization to the product. As the bending hose, as shown in Fig. 2, a central hose was used, and a straight hose was used at both ends. In the figure, 14 is a bent iron core, and 15 is a rubber hose. The greater the heat shrinkage of the reinforcing yarn used, the greater the shrinkage of the hose, especially in the straight portions at both ends. Table 3 shows the results of molding conditions and shrinkage of the hose.

[0026]

[Table 3]

From the results in Table 3, in the examples, the hose length hardly changed even after vulcanization. Therefore, it is not necessary to cut the unvulcanized rubber hose in advance in consideration of the shrinkage rate, insert the bent hose into a bent iron core, and cut the hose to a predetermined size after vulcanization. Since cutting after vulcanization is omitted, yield can be improved and cost can be reduced by omitting the cutting process.

[0028]

[Effect of device]

 In this invention, the inner coat layer and / or the outer coat layer is formed of a rubber composition in which a carboxyl group-containing acrylic copolymer elastomer is blended with a carboxyl group-containing ethylene-acrylate copolymer elastomer in a proportion of 10 to 30% by weight. As a result, a rubber hose excellent in heat resistance, cold resistance, compression set resistance and oil resistance was obtained. Furthermore, since the fiber reinforced layer was formed of aromatic polyamide fiber, a fiber reinforced rubber hose excellent in sealing property, insertability and yield was obtained.

[Submission date] June 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

[Table 1]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

[0020] In Table 1, the extrusion processability and the hose collapse resistance, L / D = 10/1 , die temperature 90 ° C., a barrel temperature of 70 ° C., extruded by Gabedai under conditions of screw rotation speed 30 rpm, extrusion processability Was comprehensively evaluated on the basis of 5 grades of surface texture at the time of extrusion, edge shape retention, and extrusion speed. The larger the number, the better, 5 is excellent, 4 is good, 3 is normal, 2 is acceptable, and 1 is not. The hose crushability was evaluated by using the plastic coder and measuring the crush after a tube having an inner diameter of 10 mm and an outer diameter of 12 mm extruded by a tubing die for 20 minutes in an oven at 150 ° C. The kneading workability was evaluated on the basis of a total of 5 grades, namely, the tackiness of the material on the roll surface when the material was kneaded with an 8-inch roll (all water cooling), the hardness of the kneading material, and the workability. The evaluation method is the same as that for extrusion processability. Viscosity is 90 ° C. , shear rate is 200 sec- ¹ , and apparent viscosity when extruded with a capillary die . Furthermore, the methods for measuring hardness (JIS-A), tensile strength at break, elongation at break, compression set, and rate of change in volume were each in accordance with JIS K6301.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a test method for sealing property.

FIG. 2 is a front explanatory view showing the shape of a bent hose in a yield test.

[Explanation of symbols]

 10 Water pressure pump 11 Nipple 12 Leaf spring clip

Claims (1)

[Scope of utility model registration request] 1. A reinforcing rubber hose comprising an inner coat layer, a fiber reinforced layer and an outer coat layer, wherein the inner coat layer and / or the outer coat layer is a carboxyl group-containing acrylic copolymer elastomer and a carboxyl group-containing ethylene-acrylate copolymer. A rubber composition is blended with a combined elastomer, and the blend ratio of the carboxyl group-containing ethylene-acrylate copolymer elastomer is 10 to 30% by weight, and the fiber reinforcing layer is formed of aromatic polyamide fibers. Fiber hose rubber hose characterized by.