JP2006052502A - Fiber cord for rubber hose reinforcement and rubber hose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rubber hose that has excellent properties of a polyethylene naphthalate fiber in comparison with a conventional polyester fiber, namely, makes the best use of high tenacity, high modulus of elasticity and high heat resistance, is inexpensive and has excellent vibration absorption properties. <P>SOLUTION: The rubber hose is obtained by using a reinforcing fiber as a reinforcing layer. The reinforcing fiber is obtained by treating a polyethylene naphthalate with a first treating agent containing a polyepoxide compound or treating the fiber in the stage of spinning or drawing with a treating agent containing a polyepoxide compound, making a twisted yarn cord and treating the twisted yarn cord with a resorcinol-formaldehyde-rubber latex (RFL). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber hose made of polyethylene naphthalate fiber having excellent dimensional stability and excellent vibration absorption as a reinforcing material for a rubber hose. More specifically, the present invention relates to a rubber hose in which a reinforcing fiber layer is braided with polyethylene naphthalate fibers having high modulus and reduced thermal shrinkage and excellent dimensional stability.

Polyester fibers have high strength and high Young's modulus, and are widely used as rubber reinforcing fibers for tires, hoses, belts, and the like as applications that make use of them. In particular, in hose reinforcement applications, it is required to have high strength against reinforcing fibers, good dimensional stability, good adhesion to rubber, and excellent fatigue properties. Polyester fibers having an excellent balance of properties are widely used (for example, Patent Documents 1 to 3).
However, in recent years, rubber hoses used in automobile engine rooms and brake system piping are required to have high physical properties for fibers for reinforcing the rubber hoses as the engine rooms become more compact and heated. It became so. Also, in terms of automobile comfort, vibration absorption performance is also important for rubber hoses in order to reduce vibration noise generated in the engine room. For example, aramid fibers may be applied to the reinforcing layer in order to improve durability and heat resistance by increasing the elastic modulus of the reinforcing layer, but there is a disadvantage that the cost increases.
Japanese Patent Laid-Open No. 09-132817 Japanese Patent Laid-Open No. 10-110390 Japanese Patent Laid-Open No. 11-286876

  The present invention is to provide a rubber hose that has excellent properties of polyethylene naphthalate fiber, that is, high strength, high elastic modulus, and high heat resistance, is inexpensive and has excellent vibration absorption characteristics as compared with conventional polyester fibers. It is what.

The present invention relates to a rubber hose using a reinforcing fiber as a reinforcing layer, wherein the reinforcing fiber is obtained by treating a polyethylene naphthalate fiber with a first treating agent containing a polyepoxide compound, or spinning or stretching the fiber. The present invention relates to a rubber hose characterized in that it is a fiber cord treated with a treating agent containing a polyepoxide compound at the stage, then formed into a twisted cord, and further treated with resorcin / formalin / rubber latex (RFL).
Here, the rubber hose of the present invention is a fiber reinforced rubber hose having a reinforcing layer composed of reinforcing fibers between the inner rubber layer and the outer rubber layer, and the reinforcing fiber is the rubber hose reinforcing cord, The reinforcing layer preferably has a spiral structure or a blade structure.
The rubber hose of the present invention preferably has a loss tangent (tan δ) at 10 Hz to 100 Hz of 0.02 or more in a temperature range of 0 to 100 ° C.

  The rubber hose using the fiber cord for reinforcing the rubber hose made of the polyethylene naphthalate fiber of the present invention as the fiber reinforcing layer has higher heat resistance, higher elastic modulus and higher strength than the conventional polyester fiber reinforced rubber hose. In addition, it exhibits an excellent effect in reducing vibration noise.

  The polyethylene naphthalate forming the polyethylene naphthalate fiber used in the present invention comprises at least 90 mol%, preferably at least 95 mol%, of ethylene-2,6-naphthalate units in all repeating units. Polyethylene naphthalate may contain other suitable units (third component) in a proportion of less than 10 mol% in all repeating units. Examples of the third component include (a) compounds having two ester-forming functional groups, such as aliphatic dicarboxylic acids such as oxalic acid, succinic acid, sebacic acid, and dimer acid, cyclopropanedicarboxylic acid, and hexahydroterephthalic acid. Arocyclic dicarboxylic acid, phthalic acid, isophthalic acid, naphthalene-2,7-dicarboxylic acid, diphenylcarboxylic acid and other aromatic dicarboxylic acids, diphenyl ether dicarboxylic acid, diphenylsulfonic acid, diphenoxyethanedicarboxylic acid, 3,5- Carboxylic acid such as sodium dicarboxybenzene sulfonate, glycolic acid, p-oxybenzoic acid, oxycarboxylic acid such as p-oxyethoxybenzoic acid, propylene glycol, trimethylene glycol, diethylene glycol, tetramethylene glycol, hexamethyl Glycol, neopentylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, p, p'-dihydroxyphenylsulfone, 1,4-bis (β-hydroxyethoxy) benzene, 2,2- Oxy compounds such as bis (p-β-hydroxyethoxyphenyl) propane and polyalkylene glycol, functional derivatives thereof, high polymerization compounds derived from the above carboxylic acids, oxycarboxylic acids, oxy compounds or functional derivatives thereof And (b) a compound having one ester-forming functional group, such as benzoic acid, benzyloxybenzoic acid, and methoxypolyalkylene glycol. Furthermore, (c) a compound having three or more ester-forming functional groups, such as glycerin, pentaerythritol, trimethylolpropane, etc. can be used within the range where the polymer is substantially linear. Needless to say, these polyesters may contain matting agents such as titanium dioxide, and stabilizers such as phosphoric acid, phosphorous acid, and esters thereof.

  Moreover, the single yarn fineness of the polyethylene naphthalate fiber used for this invention is 2-5 dtex, Preferably it is 3-4 dtex. When the single yarn fineness exceeds 5 dtex, the stress applied to the single yarn when twisted into a cord is increased, not only the strength is decreased, but also the fatigue resistance is decreased. On the other hand, if it is less than 2 dtex, the convergence of single yarns is excessively increased and the contact area between the single yarns is increased, so that when it is made into a twisted yarn cord, it becomes hard and the fatigue resistance is also lowered.

  The polyethylene naphthalate forming the fiber of the present invention preferably has an intrinsic viscosity of 0.7 dL / g or more. More preferably, it is 0.7-1.0 dL / g. Here, the intrinsic viscosity referred to in the present invention is a value obtained from the viscosity measured at 35 ° C. by dissolving the fiber in a mixed solvent of phenol and orthodichlorobenzene (volume ratio 6: 4). If the intrinsic viscosity is less than 0.7 dL / g, the strength and toughness of the fiber tend to decrease. On the other hand, fibers having an intrinsic viscosity exceeding 1.0 dL / g tend to have a poor spinning process and are difficult to produce.

  Further, the polyethylene naphthalate fiber used in the present invention preferably has a strength per dtex (cN / dtex) of 8 or more, more preferably 8.0 to 9.5, and particularly preferably 8.5 to 9. 0 is desirable. If the strength is less than 8 cN / dtex, the strength tends to be inferior.

  Polyethylene naphthalate fiber having such strength can be produced by a conventionally known method for producing polyester fiber. More specifically, for example, an undrawn yarn obtained by melt-spinning polyethylene naphthalate, a method of winding and then drawing separately after spinning, or a method of drawing continuously without winding up the undrawn yarn, etc. It can be manufactured by a method. The resulting fiber has a high modulus and excellent dimensional stability.

  In the present invention, a smoothing agent may be attached to the polyethylene naphthalate fiber, and the adhesion amount of the smoothing agent component to the fiber weight is preferably 0.2 to 0.6% by weight, A preferable adhesion amount is 0.3 to 0.5% by weight. When the adhesion amount of the smoothing agent is less than 0.2% by weight, not only the smoothness of the original yarn is lost and the yarn forming and post-processing properties are deteriorated, but also the cord after the adhesive treatment is hardened and the fatigue resistance. May get worse. On the other hand, if it exceeds 0.6% by weight, the adhesiveness may decrease.

  Specific examples of the smoothing agent component include hydrocarbons such as mineral oil, esters of higher alcohols and higher fatty acids such as butyl stearate, oleyl laurate, isostearyl palmitate, oleyl oleate, dioctyl sebacate, dioctyl azelate, Esters of higher alcohols and aliphatic dibasic acids such as dioleyl adipate, esters of dihydric alcohols and higher fatty acids such as neopentyl glycol dilaurate, diethylene glycol dilaurate, diethylene glycol diolate, glycerol triolate, trimethylolpropane decanate, etc. Trihydric alcohol and higher fatty acid esters, pentaerythritol tetraoleate and other higher alcohols and higher fatty acid esters, dioleyl phthalate, trioctyl trimellime Over DOO, an ester of a higher alcohol and aromatic carboxylic acids such as tetraoctyl pyromellitate and the like.

  In addition, the polyethylene naphthalate fiber used in the present invention may be attached with an emulsifier, and the amount of the emulsifier attached to the fiber weight is preferably 0.05 to 0.15% by weight. Preferably it is 0.08 to 0.12% by weight. When the adhesion amount of the emulsifier is less than 0.05% by weight, the wettability of the raw yarn with respect to water decreases, and in particular when using an aqueous adhesive, it may be difficult to uniformly apply the adhesive. . On the other hand, if it exceeds 0.15% by weight, the adhesiveness may decrease.

  Specific examples of the emulsifier component include higher alcohol alkylene oxide adducts, alkylphenol ethylene oxide (hereinafter referred to as EO) adducts, polyethylene glycol esters, and polyhydric alcohol ester ethylene oxide adducts. More specifically, hydrogenated castor oil ethylene oxide (EO) 5-25 mol adduct, hydrogenated castor oil ethylene oxide (EO) 5-25 mol adduct trioleate, hydrogenated castor oil ethylene oxide (EO) 5-25 mol Adduct dioleate, castor oil ethylene oxide (EO) 5-25 mol adduct trioleate, castor oil ethylene oxide (EO) 5-25 mol adduct dioleate, hydrogenated castor oil ethylene oxide (EO) 5-25 mol adduct distearate Castor oil ethylene oxide (EO) 5-25 mol adduct tristearate, castor oil ethylene oxide (EO) 5-25 mol adduct distearate, trimethylolpropane (EO) 15-25 mol adduct dioleate, trimethylolpropane (EO) 15-25 mole adduct di Tearate, sorbitol (EO) 15-40 mol adduct pentaoleate, sorbitol (EO) 15-40 mol adduct tetrastearate, sorbitol (EO) 15-40 mol adduct trioleate, pentaerythritol (EO) 15-40 Mole adduct triolate, pentaerythritol (EO) 15-40 mol adduct tristearate, hydrogenated castor oil ethylene oxide (EO) 5-25 mol adduct stearate maleate compound and the like.

  The above-mentioned smoothing agent and emulsifier may be applied by any conventionally known method, but is generally applied by an oiling roller at the stage of undrawn yarn immediately after spinning.

The fiber cord for rubber hose of the present invention is obtained by treating the polyethylene naphthalate fiber as described above with a first treatment agent containing a polyepoxy compound, or treating with a polypolyepoxy compound at the time of spinning or drawing at the stage of fiber production. Has been.
Here, the adhesion amount of the epoxy compound is preferably 0.05 to 0.3% by weight, more preferably 0.1 to 0.2% by weight with respect to the fiber weight of the polyethylene naphthalate fiber. is there. If the adhesion amount is less than 0.05% by weight, the adhesiveness is lowered. On the other hand, if it exceeds 0.3% by weight, the cord after the adhesive treatment is hardened and the fatigue resistance is lowered.

The epoxy compound attached to the fiber of the present invention preferably has two or more epoxy groups in one molecule. For example, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol Examples thereof include glycidyl ether compounds such as polyglycerol glycidyl ether, and these may be used alone or in combination of two or more. These epoxy compounds are usually applied on the fiber as an aqueous solution or aqueous dispersion, but it is preferable to use an epoxy group curing catalyst in combination.
Preferred examples of the epoxy group curing catalyst include amine compounds and acid anhydrides. In particular, amines such as aliphatic polyamines, modified aliphatic polyamines, aromatic polyamines, modified aromatic polyamines, alicyclic polyamines, modified alicyclic polyamines, polyamidoamines, modified polyamidoamines, and tertiary amines are preferred. These compounds may be used alone or in combination of two or more.
In addition, since the thing which has an emulsifying effect | action among these compounds also acts as an above-mentioned emulsifier component, the adhesion amount of the thing is contained in the emulsifier adhesion amount.

  The epoxy compound and the epoxy curing catalyst can be applied to the unstretched yarn before stretching or the stretched yarn after stretching even if they are mixed and applied separately, for example, to the unstretched yarn before stretching. Any method may be employed such as applying an epoxy compound after stretching, or applying an epoxy compound after applying an epoxy curing catalyst to the drawn yarn. However, from the viewpoint of the stability of the oil agent, a method of separately providing the epoxy compound and the epoxy curing catalyst is more preferable. At this time, in the adhesion treatment liquid, other treatment agent components described above, for example, normal oil agent components, mineral oil, smoothing agents such as fatty acid esters, higher alcohol ethylene oxide adducts, hardened castor oil ethylene oxide adducts, etc. In order to achieve the object of the present invention, the final amount of the smoothing agent component and the emulsifier component should be within the above-mentioned range. Is important to. By optimizing the adhesion amount of the smoothing agent component and the emulsifier component, the epoxy film as the adhesion mediating layer is uniformly and firmly formed, and the RFL adhesive layer used for subsequent adhesion to the rubber is uniform. Since it adheres, high adhesion and fatigue resistance in rubber are finally obtained.

  Moreover, it is preferable that the adhesion amount of components other than the smoothing agent, the emulsifier and the epoxy compound is as low as possible. Furthermore, in order to accelerate the curing of the epoxy compound, it is more preferable to heat-treat the polyethylene naphthalate fiber after spinning at 40 ° C. or more for 2 days or more.

  Such polyethylene naphthalate fiber for reinforcing rubber is further twisted to form a pretreatment cord for reinforcing rubber.

  Here, the twist coefficient (TM) of the twisted cord is preferably 1 or more. The twist coefficient (TM) is defined by the following formula (1).

TM = 0.00323 × (denier of yarn) ^1/2 × (twist number / 10 cm) (1)
The total fineness of the yarn used is preferably about 550 to 11,000 dtex. A multifilament yarn of 550 to 3,300 dtex is generally used as the twisted yarn cord. The generated code is usually in the range of 1,100 to 20,000 dtex. There are two methods for producing a twisted cord: one is twisting one yarn in one direction and the other is twisting two or more yarns like a rope. When two or more yarns are twisted together, each yarn is preliminarily twisted with the same number of twists, and then these yarns are aligned and the upper twists of approximately the same number of twists are applied in the opposite direction. In this case, the twist coefficient is calculated by using the total fineness of the yarns combined as the total fineness, and using the value of the lower twist or the higher twist as the number of twists.

  After forming the twisted yarn cord, a tension heat treatment is performed at an elongation of 4 to 30% at a temperature of 100 to 350 ° C. to relax the molecules of the rigid polyethylene naphthalate, and at the same time, between yarns generated during twisting It is preferable to remove the strain between the single yarns. This is only effective for rigid polyethylene naphthalate fibers and has little effect on conventional hot melt polymers such as polyethylene terephthalate, nylon 6 or nylon 66. This is because polyethylene terephthalate, nylon 6 or nylon 66 has a sufficiently flexible molecular skeleton, so even when twisted yarns with a high twisting coefficient are applied, single yarns and yarns can follow flexibly, and the elongation of the yarn is 10 to 20%. This is because the strain at the time of twisting can be absorbed. Since the yarn elongation of the polyethylene naphthalate fiber having a high elastic modulus is 5 to 12%, the tension heat treatment is a processing under extremely high tension. The heat treatment temperature when tensioning the twisted cord is preferably 100 to 350 ° C. More preferably, it is 150-300 degreeC. When the temperature is less than 100 ° C., the increase in strength of the twisted cord is small. On the other hand, when the temperature exceeds 350 ° C., the fiber deteriorates. The heater can be a contact type hot plate or a non-contact type cylindrical or slit type heater.

  The elongation percentage is preferably 4 to 30%. Here, the expansion rate is defined as follows. That is, when the drawing speed at which the twisted cord is unwound from the bobbin is V0, and the roll speed at which the twisted cord is drawn after the tension heat treatment is Vh, the elongation rate is obtained by the following equation (2).

Elongation rate = [(Vh−V0) / V0] × 100 (2)
The expansion may be performed in one stage or may be performed in two or more stages. There are two methods of tension heat treatment: a method in which the twisted cord is stretched and then heat treated, and a method in which the heat treatment is performed at the same time while being substantially stretched. However, the latter method is preferable because the elongation rate can be increased. The twisted cord that has been subjected to the tension heat treatment may be wound while being naturally cooled, or may be wound after being cooled once with a cooling roll.

  If the elongation rate is less than 4%, the tension is insufficient and the strength of the twisted cord is not improved so much. On the other hand, when the elongation rate exceeds 30%, the polyethylene naphthalate fiber is overstrained, and troubles such as broken yarns occur. The optimization of the elongation rate is affected by the twisting coefficient and the processing temperature. However, when the twisting coefficient is high or when the processing temperature is high, the strength and modulus of the twisted cord are likely to increase when the elongation rate is increased. The tension heat treatment may be performed as an independent process, or may be performed continuously while performing chemical treatment in other processing steps.

The fiber cord for reinforcing a rubber hose of the present invention is obtained by treating the twisted cord thus obtained with an adhesive containing RFL (resorcin / formalin / latex).
Here, RFL is used in a molar ratio of resorcin to formaldehyde of 1: 0.1 to 1: 8, preferably 1: 0.5 to 1: 5, more preferably 1: 1 to 1: 4. .
The mixing ratio of resorcin / formalin and rubber latex is preferably in the range of 1: 1 to 1: 5, preferably 1: 3 to 1:12 in terms of solid content. The type of rubber latex is selected depending on the rubber type of the adherend.

  Examples of rubber latex include polybutadiene latex, natural rubber latex, styrene / butadiene copolymer latex (PB), vinylpyridine / styrene / butadiene / terpolymer latex (VP), nitrile rubber latex, hydrogenated nitrile rubber latex, and chlorosulfonation. Polyethylene latex, chloroprene rubber latex and the like can be used in combination. In addition, as shown in Japanese Examined Patent Publication No. 57-21857, the general formula

(Wherein R ′ is an aromatic or aliphatic hydrocarbon residue, n is 0, 1 or 2) and is reacted with an oxime, phenol, caprolactam, etc. In some cases, the blocked isocyanate obtained is added.
The ethylene urea compound is usually added in an amount of 0.5 to 30% by weight with respect to RFL in the form of an aqueous dispersion. After being treated with RFL, it may be treated with rubber paste containing the same kind of rubber as the rubber matrix.

After the above RFL treatment, it is dried at 80 to 150 ° C. for 0.5 to 5 minutes, and then heat treated and cured at 150 to 260 ° C. for 0.5 to 5 minutes.
The amount of RFL attached to the fiber cord is adjusted to 1 to 10% by weight.

Thus, by subjecting the twisted cord obtained as described above to adhesion treatment with an adhesive containing RFL, it is possible to obtain a rubber molded article such as a rubber hose having excellent adhesion and excellent durability. A possible rubber hose reinforcing fiber cord is obtained.
As described above, the rubber molded product of the present invention includes a rubber hose, a belt, a tire, and the like, depending on the type of fiber cord.

The fiber cord for reinforcing a rubber hose of the present invention is useful as a reinforcing layer of a rubber hose.
In particular, in a fiber reinforced rubber hose having a fiber reinforcing layer made of reinforcing fibers between an inner rubber layer and an outer rubber layer, the reinforcing cord has the structure of the reinforcing layer using the rubber hose reinforcing cord of the present invention as the reinforcing fiber. A rubber hose having a spiral structure or a blade structure has a high modulus, a reduced thermal shrinkage ratio, and excellent dimensional stability, which is a preferred embodiment.

  That is, the fiber cord for reinforcing a rubber hose of the present invention obtained as described above is a known technique, for example, the obtained fiber cord is subjected to a predetermined density by a brader on an inner layer made of tube rubber. Arrange at an angle. Next, after an interlayer rubber sheet is disposed thereon, the fiber cord is again disposed by a blader, and this is performed a predetermined number of times. Finally, after an outer layer made of a cover rubber for protecting the outer reinforcing fiber is disposed, this is steam vulcanized in, for example, a steam vulcanizer to form a rubber hose. The fiber cords may be arranged in a spiral structure.

  Here, as the rubber of the inner layer, the interlayer, and the outer layer, NBR, CR, hydrogenated NBR (HNBR), CSM, etc. are used for the inner layer, and NBR for the interlayer, NBR, CR, CSM for the outer layer, etc. Is used.

The rubber hose of the present invention preferably has a loss tangent (tan δ) at 10 Hz to 100 Hz of 0.02 or more in a temperature range of 0 to 100 ° C.
Here, the loss tangent is the ratio of the energy dissipated as heat during one cycle of vibration to the maximum energy stored. The larger the value, the greater the internal loss and the better vibration absorption performance. It can be said that.
If each loss tangent is less than 0.02, vibration absorption performance is inferior, and the effect of reducing vibration and noise generated in the engine room is reduced.

Hereinafter, the present invention will be specifically described by way of examples, but is not limited thereto.
[Example 1, Comparative Examples 1-2]
A multifilament composed of polyethylene naphthalate fibers (PEN) manufactured by Teijin Techno Products Co., Ltd. and having a total fineness of 1,100 dtex and 350 filaments was twisted at 10 T / 10 cm to obtain a twisted cord. The cord is previously treated with a treatment liquid containing polyepoxide compound in a multifilament (Denacol EX-313 manufactured by Nagase) (heat treatment condition after treatment = 230 ° C., the amount of fibers attached is 0.07% by weight in terms of solid content) ), And then twisted cord, and RFL adhesive (10 parts by weight of resorcin, 15 parts by weight of 35% by weight formalin, 3 parts by weight of caustic soda, 250 parts by weight of water, ripened for 5 hours at room temperature) , 40 wt% vinylpyridine SBR rubber latex and 60 wt% natural rubber latex were mixed at a weight ratio of 1: 1 to obtain an adhesive solution) (heat treatment conditions after treatment = dry at 100 ° C. for 2 minutes) And heat treatment at 230 ° C. for 2 minutes).
A rubber hose was produced by a conventional method using the obtained fiber-treated cord as a reinforcing material and NBR as rubber for the inner layer, the interlayer, and the outer layer.
As comparative examples, except that polyethylene terephthalate fiber ("Tetron") (PET) manufactured by Teijin Techno Products Co., Ltd. and aramid fiber ("Twaron") (Aramid) manufactured by Teijin Twaron Co., Ltd. were used In the same manner as in No. 1, a rubber hose was obtained. Table 1 shows the comparison results of heat resistance, dimensional stability index, durability, vibration absorption, and cost in the obtained rubber hose.
Each test was performed as follows.

(1) heat resistance;
After leaving the rubber hose in the constant temperature layer at 150 ° C., the rubber hose was taken out at regular intervals and pressurized with nitrogen in water to confirm gas leakage.
(2) dimensional stability;
The ratio of dimensional change was determined by measuring the length of the hose before and after the treatment by allowing it to stand for 30 days while passing wet steam with a pressure of 5 kg / cm ² and a temperature of 150 ° C.
(3) Durability;
The pressure was 5 kg / cm ² , the temperature was 150 ° C., and the wet hose steam was passed through for 30 days.
(4) vibration absorption;
Using a viscoelasticity measuring device (VES-HC type) manufactured by Iwamoto Seisakusho, the loss tangent (tan δ) at a frequency of 10 Hz to 100 Hz was measured and judged according to the following criteria.
A: Loss tangent exceeds 0.03.
○: Loss tangent is 0.025 to 0.03
Δ: Loss tangent is less than 0.02 to 0.025 ×: Loss tangent is less than 0.02

The rubber hose of the present invention is a fiber reinforced rubber hose having a fiber reinforcing layer between an inner rubber layer and an outer rubber layer, wherein the reinforcing fiber is polyethylene naphthalate (PEN). Polyethylene naphthalate fiber is less expensive than aramid fiber, has higher heat resistance, higher elastic modulus, and higher strength than polyethylene terephthalate, and has high internal loss at room temperature and excellent vibration absorption characteristics. For this reason, the rubber hose of the present invention is particularly useful for a rubber hose used in an engine room of an automobile or for brake system piping.

Claims (3)

  A rubber hose comprising a reinforcing fiber as a reinforcing layer, wherein the reinforcing fiber is obtained by treating a polyethylene naphthalate fiber with a first treating agent containing a polyepoxide compound, or at the stage of spinning or drawing of the fiber. A rubber hose characterized by being a fiber cord which is treated with a treating agent containing a compound, then formed into a twisted cord, and further treated with resorcin / formalin / rubber latex (RFL).   A fiber-reinforced rubber hose having a reinforcing layer made of reinforcing fibers between an inner rubber layer and an outer rubber layer, wherein the reinforcing fiber is the fiber cord according to claim 2 and the structure of the reinforcing layer is spiral. The rubber hose according to claim 2, which is a structure or a blade structure. The rubber hose according to claim 1 or 2, wherein a loss tangent (tan δ) at 10 Hz to 100 Hz is 0.02 or more in a temperature range of 0 to 100 ° C.