JPH02147327A - Cord for reinforcing rubber hose - Google Patents

Abstract

PURPOSE:To obtain excellent fatigue resistance and the durability against the peeling from rubber, even when high pressure is repeatedly applied by a method in which the composite film which is composed of polyester and has the core component in a specified ratio and further has a specified strength, elongation, initial tensile resistance and dry heat shrinkage factor is twisted and formed. CONSTITUTION:The content of polyester core component of composite fiber is 30-90wt%, and the composite fiber has the high strength >=7.5g/d, the initial tensile resistance >=60g/d, the elongation <=20% and the dry heat shrinkage factor <=7%. Oriented yarns are twisted on arranged, thereby obtaining an untreated cord, and after it has been treated with the adhesive having resorcin as main component, the treated cord is obtained by treating under heating. An inner rubber layer is extrusion-molded on the outer periphery of the flexible mandrel made of resin rubber, and is put in a vulcanizing can, and then the inner rubber layer is vulcanized on semivulcanized, and further the intermediate rubber layer is extrusion-molded on the outer periphery of the inner rubber layer. The treated cord composed of said composite fiber is applied onto the outer periphery of the intermediate rubber layer. Thus, the fiber reinforced layer is formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cord for reinforcing a rubber hose.
Specifically, the present invention relates to a rubber hose reinforcing cord made of a core-sheath type composite fiber whose main components are polyester as a core component and polyamide as a sheath component.

[Prior Art] A hose using a reinforcing cord made of polyester IN whose main repeating unit is polyethylene terephthalate as a reinforcing material is disclosed in, for example, JP-A-62-1598.
It is described in Publication No. 82.

[Problems to be Solved by the Invention] In the case of a rubber hose using a rubber reinforcing cord made of a polyester core component as a reinforcing material, as described in JP-A-62-159882, it has excellent dimensional stability and is superior to ordinary Although it is effectively used as a water supply hose, as the performance of fluid equipment increases, the pressure of the working fluid increases, causing fatigue of the polyester fibers and separation of the rubber and polyester fibers, causing the hose to deteriorate in a relatively short period of time. It has been found that damage problems occur, particularly when repeated pressure is applied to the hose, and result from the cords rubbing against each other.

The object of the present invention is to solve the problems in the prior art mentioned above, and in particular, to provide a material that has extremely excellent fatigue resistance and durability against peeling from rubber even when high pressure is applied repeatedly. The object of the present invention is to provide a rubber hose reinforcing cord having dimensional stability and heat resistance, and a rubber hose reinforced using the rubber hose reinforcing cord.

[Means and Effects for Solving the Problems] The present invention has the following features: (1) A cord for reinforcing a rubber hose, in which the miscellaneous material forming the cord has a core component made of polyester containing ethylene terephthalate as a main component; It is a core-sheath type composite fiber with a sheath component mainly composed of polyamide surrounding the core component, the proportion of the core component consisting of polyester is 30 to 90% by weight, and the strength of the composite fiber is 7.3 o/d. or more, elongation is 20% or less, initial tensile resistance is 580/d or more,
A rubber hose reinforcing cord characterized by being made of twisted composite fibers with a dry heat shrinkage rate of 7% or less.

(2) The rubber hose reinforcing cord according to item (1), characterized in that the terminal modulus of the composite fiber is 20 o/d or less and the initial tensile resistance is 90 g/d or more.

(3) In (1) above, the polyester forming the core component of the composite fiber has an intrinsic viscosity (η) of 0.8 or more, a birefringence of 160 x 10°3 to 190 x 10', and a density of 1.39.
50/cm3 or more, the peak temperature of the melting curve measured by DSC is 247°C or more, the sulfuric acid relative viscosity (ηr) of the polyamide forming the sheath component is 2.8 or more, and the birefringence is 50
x10-1 or more, a density of 1,1400/cIR" or more, and both the core component and sheath component have a highly oriented and highly crystalline fiber structure.

It is in.

The rubber hose reinforcing cord according to the present invention is a composite fiber made of polyester as a core component and polyamide as a sheath component. properties, and the exfoliation durability of the polymer at the core-sheath composite interface, and these properties depend on the specific birefringence, density, and
and DSC melting peak temperature, and polyester core component I
! It can be expressed by a parameter consisting of a combination of high initial tensile resistance and low terminal modulus.

The polyester that is the core component of the composite fiber has an ultimate viscosity r
! By setting X(η) to 0.7 or more, preferably 0°8 or more, the strength of the composite Il miscellaneous material can be increased to 7.5 q/d or more.

Similar to the polyester core component, the polyamide sheath component polymer also requires a high degree of polymerization in order to obtain a high-strength conjugate fiber, and the relative viscosity of the sulfuric acid is 2.8 or more, preferably 3.0 or more.

Copper salts and other organic and inorganic compounds are added to the polyamide sheath component as thermal oxidative deterioration inhibitors. In particular, copper salts such as iodized steel, copper acetate, copper chloride, and copper stearate should be used at 30 to 500 ppm as copper, and alkali metal halides such as potassium iodide, sodium iodide, and potassium bromide should be added at 0.0 ppm.
It is preferable to contain 1 to 0.5% of heavy chain and/or 0.01 to 0.1% by weight of an organic or inorganic phosphorus compound.

The ratio of the polyester core component of the composite fiber is 30 to 90
Weight%. When the polyester component is less than 30% by weight, the polyester component effectively utilizes the modulus and dimensional stability. ilN, and a desirable rubber hose reinforcing cord cannot be obtained.

On the other hand, if the polyester core component accounts for 90ffi or more, when the composite fiber is used as a cord for reinforcing a rubber hose and the cord is used as a tensile material for a rubber hose, the adhesion to the rubber is poor, and the rubber hose in the rubber has poor adhesion. It is not possible to improve the heat resistance of the reinforcing cord.

In the composite m-fiber, both the polyester core component and the polyamide sheath component are highly oriented and crystallized, and the birefringence of the polyester core component is 160 x 104 to 190 x 10.
It is desirable to keep it within the range of 160X1
If it is less than 0', the strength of the composite fiber may not be 7.50/d or more, and the initial tensile resistance may not be 60 g/d or more.

Moreover, if it exceeds 190 x 10', dimensional stability and fatigue resistance may not be improved.

On the other hand, the birefringence of the polyamide sheath component is 50X10-3 or more, usually 55X10'' or more, which is highly oriented.
If it is less than 0x10-1, it is difficult to obtain a composite material having high strength and high initial tensile resistance.

The birefringence of the core-sheath composite mH can be measured as follows. That is, the sheath portion is directly measured using a transmission interference microscope, and the core portion is measured using a transmission interference microscope after dissolving the polyamide sheath component in formic acid, sulfuric acid, fluorinated alcohol, or the like.

It is desirable that the polyester core component has a density of 1.395q/ClA3 or more and the polyamide sheath component has a density of 1.140o/13 or more, and that they are highly crystallized.By having a density of each of the above specific ratios or more, the composite 1Itd1
It has excellent dimensional stability and fatigue resistance, and when the cord is made into a rubber hose reinforcing cord and used as a tensile member of a rubber hose, the heat resistance in the rubber of the tensile member is significantly improved.

The density of the polyester core component can be determined by dissolving and removing the polyamide sheath component with formic acid, sulfuric acid, fluorinated alcohol, etc., and the density of the polyamide sheath component can be calculated from the density of the composite fiber and the density of the polyester core. can.

The peak temperature of the DSC melting curve showing the characteristics of the crystal structure of the polyester core component in the composite m-fiber is 247 ° C.
The temperature is preferably 248° C. or higher. The higher the peak temperature, the larger the crystal and/or the better the crystal integrity and the more stable the mei structure. The melting peak temperature of the polyester core component fiber is 24
If the temperature is less than 7℃, the desired modulus, dimensional stability,
and fatigue resistance may not be obtained.

Another feature that reflects the rough structure of the composite fiber is that the polyester core component iIN has a high initial tensile resistance of 90 (1/d or more) and a low terminal modulus of 20 g/d or less.High initial tensile resistance The characteristics of polyester fibers, which have high elasticity and low terminal modulus, are that there is little loss of strength during the rubber hose processing process.
It is associated with improved fatigue resistance. Terminal modulus is the value obtained by dividing the stress increment between the point on the SS curve subtracted by 2.4% from the breaking elongation and the breaking point by 2.4 x 10-2 in the tensile test of m-fiber. 0/d), and the conditions of the tensile test are J 13-Ll 017 8° Composite! characterized by the above! I miscellaneous is 7°50
It has high strength of /d or more, initial tensile resistance of 60Q/d or more, and elongation of 20% or less.

More preferable properties of the composite fiber are strength of 80/d or more, initial tensile resistance of 70 Q/d or more, and elongation of 8 to 16%, which can be achieved by appropriately combining the above conditions.

The composite I1M is manufactured by the novel method described below.

In order to obtain the polymer physical properties of the polyester core component described above, a polymer consisting essentially of polyethylene terephthalate and having an intrinsic viscosity (η) of 0.75 or more, usually 0.85 or more is used. Furthermore, in order to obtain l1M with excellent heat resistance, it is important to spin a polymer with a low concentration of carboxyl end groups. For example, techniques such as adopting a low-temperature polymerization method or adding a sequestering agent during the polymerization or spinning process are applied, and examples of the sequestering agent include oxazolines, epoxies, carbodiimides, ethylene carbonate, oxalate esters, and malon. Acid esters, etc.

The polyamide sheath component polymer has a sulfuric acid relative viscosity of 2°8 or more,
Usually, a polymer with a high polymerization degree of 3.0 or more is used.

It is preferable to use two extruder type spinning machines for melt spinning the polymer. The polyester and polyamide polymers melted by each extruder are introduced into a composite spinning pack, and spun into a composite fiber with polyester in the core and polyamide in the sheath through a composite spinning nozzle.

The spinning speed is 1500 m/min or more, preferably 2000 m/min.
The speed should be at least 1/min. Immediately below the spinneret, 10cIR or more, 200°C or more within 1m, preferably 26
A heated atmosphere of 0°C or higher is created by providing a heat insulating cylinder, a heating cylinder, etc. After passing through the above heating atmosphere, the spun yarn is quenched and solidified with cold air, and then, after being applied with an oil agent, it is taken off by a take-off roll that controls the spinning speed. Control of the heating atmosphere directly below the spinneret is important in order to maintain spinnability during high-speed spinning. The taken-off undrawn yarn is usually continuously drawn without being wound up. The birefringence of the undrawn yarn sampled on a take-up roll for the purpose of understanding the physical properties of the undrawn yarn before stretching is that the polyamide sheath part is 20x10-3 or more, preferably 30x10-3 or more, and the polyester core part is also 20x10 or more. Preferably 30X10-3 or more and f! It is oriented to the degree.

The adoption of high-speed spinning improves the modulus, dimensional stability, and
This brings about the effect of improving fatigue resistance, but surprisingly, the durability of the core-sheath composite interface is significantly improved. Unlike the conventional low-speed spinning method, in which a highly hygroscopic and crystallized polyamide component is combined with an amorphous polyester component, in the B-speed spinning method, the polyamide component,
It is thought that the fact that both the polyester components are in a state where oriented crystallization progresses, and that the stretching ratio after spinning is small can contribute to the durability of the composite interface.

Next, the undrawn yarn is continuously heated to 180°C or higher, preferably 2°C.
It is hot stretched at a temperature of 00°C or higher.

The stretching is carried out in two or more stages, usually three or more stages, and the stretching ratio is in the range of 1.4 to 3.5 times. The use of such high-temperature thermal stretching according to the present invention also contributes to improving the composite interface durability. The stretching temperature in the third stage of the stretching is low, for example 160
When stretched at temperatures below 180 °C, interfacial delamination between the polyester core component and polyamide sheath component may occur during rubber hose processing and when the rubber hose is repeatedly used at high pressure.

As a method for obtaining the rubber boce according to the present invention using the composite fiber according to the present invention, for example, the obtained drawn yarn is heated or pulled together to form an untreated cord, and the untreated cord is treated with resorcin, formalin, or latex. After being treated with an adhesive whose main ingredients are Then, an inner rubber layer is extruded on the outer periphery of a flexible mandrel made of resin or rubber, placed in a vulcanizing can, and the inner rubber layer is vulcanized or semi-vulcanized. An intermediate rubber layer is extrusion molded on the outer periphery of the inner rubber layer, and a fiber reinforced layer is molded on the outer periphery of the intermediate rubber layer using a treated cord made of the composite van according to the present invention. The outer rubber layer is extruded and the whole is put into the vulcanizing can again and vulcanized as a unit.

Further, when the IN reinforcing layer is formed into a plurality of layers, insulation is formed between the first fiber reinforcing layer and the second fiber reinforcing layer.

[Example] Example-1 and 2) Comparative Examples 1 to 4 Intrinsic viscosity (η) 1.05, carboxyl end group concentration 10
．． 5eQ/10”Q polyethylene terephthalate (
PET) and 0.02% by weight of iodized steel and 0.02% by weight of potassium iodide.
1 wt.
) were each melted using a 40φ Ktruder-type spinning machine, introduced into a composite spinning pack, and spun from a core/sheath composite spinneret into a composite yarn of polyethylene terephthalate in the core and polyamide in the sheath.

The proportions of the core component and sheath component were varied as shown in Table 1. The cap used had a hole diameter of 0.4 mφ and a number of holes of 120. Polyethylene terephthalate and polyamide were melted at a temperature of 295°C and 290°C, respectively, and the spinning pack temperature was set at 300°C for spinning. 15c right below the base! A R heating cylinder was attached and the cylinder was heated to an atmospheric temperature of 290°C. The ambient temperature is the ambient temperature m degrees measured at a position 10 clI below the mouth surface and 1 cIRIll from the outermost thread. Goodness 40 under the heating cylinder
A 0#lII annular chimney was installed, and cold air was blown at 40 m/min at 25°C from around the yarn at right angles to the yarn.
Cooled. After applying an oil agent, the yarn speed was controlled with a take-up roll rotating at the speed shown in Table 1, and then the yarn was drawn continuously without being wound up. The film was stretched in three stages using five pairs of Nernon type rolls, then subjected to a relaxation heat treatment of 3% and then wound up. The stretching conditions were a take-up roll temperature of 60°C and a first stretching roll temperature of 120°C.
, the temperature of the second stretching roll was 190°C, the temperature of the third stretching roll was 225°C, the tension adjustment roll after stretching was not heated,
The stage stretching ratio was 70% of the total stretching ratio, and the remainder was divided into two stages for stretching. The yarn was produced by varying the spinning speed, total draw ratio, etc., and the discharge amount was changed in accordance with the spinning speed and draw ratio so that the fineness of the drawn yarn was about 500 denier (Example 1.2) Comparative example 1, 2). Three of the obtained drawn yarns were combined to have a denier of 1,500.

The spinning conditions, the obtained drawn yarn properties, and the Allff structural parameters were determined using polyethylene terephthalate (PET)1.
1M (1500-288-7020) (Comparative Example 3) and nylon 661a fiber (1260-204-1781)
A comparative test was conducted on (Comparative Example 4). Each condition and fiber properties are as shown in Table 1.

(Hereinafter, blank spaces) Using each of the fibers shown in Table 1 above, these llH were twisted and twisted by 407/10 cm in opposite directions to obtain a raw cord of 1500/2. However, comparative example 3
N66 has a twist number of 39T/10cII and a twist of 1260/10cII.
2 raw code. This raw cord was applied with an adhesive and heat-treated in a conventional manner using a dipping hoe manufactured by Riller Co., Ltd. to obtain a dip cord.

The dip liquid contained an adhesive component consisting of 20% resorcinol, formalin, and latex, and was adjusted so that about 4% of the adhesive component adhered to the cord. Heat treatment is 225℃ and 80℃
The process was performed while stretching the dip cord so that its intermediate elongation was approximately 5%. Nylon 66 was stretched under the same heat treatment conditions so that the intermediate elongation was approximately 9%. In addition, PET was subjected to two-bath adhesion treatment using a conventional method, and heat treatment was performed at 240°C for 120 seconds, resulting in an intermediate elongation of approximately 5.
%.

Regarding the thus obtained dip cord, a test piece was made embedded in rubber in the same manner as when used as a tensile member for a rubber hose, and heat resistance, adhesion, fatigue resistance, etc. in rubber were evaluated. The results were as shown in Table 2.

(Left below) The rubber hose reinforcing cord according to the present invention has a modulus and dimensional stability equal to or higher than that of conventional polyester fiber cords, and also has a higher modulus and dimensional stability than conventional polyester fiber cords. This shows that it is a high-strength cord with significantly improved heat resistance, heat-resistant adhesion, and fatigue resistance.

Furthermore, the rubber hose reinforcing cord according to the present invention has significantly improved modulus and dimensional stability compared to conventional nylon m-fiber cords.

[Effects of the Invention] The rubber hose reinforcing cord according to the present invention has a modulus equal to or higher than that of conventional polyester and improved dimensional stability, and can be applied to a rubber hose in which a reinforcing cord made of conventional polyester is embedded. In comparison, the heat resistance and adhesion in the rubber of the cord embedded in the rubber hose according to the present invention, especially the heat resistance adhesion after high temperature history, and the fatigue resistance are significantly improved, so that the rubber hose has improved durability against repeated fatigue. The properties are extremely good.

Claims (3)

[Claims] (1) In a cord for reinforcing rubber hoses, the fibers forming the cord have a core-sheath type composite in which a core component is polyester mainly composed of ethylene terephthalate, and a sheath component mainly composed of polyamide surrounds the core component. A fiber, the proportion of the core component made of the polyester is 30 to 90% by weight, the strength of the composite fiber is 7.3 g/d or more, the elongation is 20% or less, and the initial tensile resistance is 58 g/d or more. ,
A rubber hose reinforcing cord characterized by being made of twisted composite fibers with a dry heat shrinkage rate of 7% or less. (2) In the rubber hose reinforcing cord according to claim (1), the terminal modulus of the composite fiber is 20.
A rubber hose reinforcing cord characterized by having an initial tensile resistance of 90 g/d or more. (3) In claim (1), the polyester forming the core component of the composite fiber has an intrinsic viscosity (η) of 0.
8 or more, birefringence is 160 x 10^-^3 ~ 190 x 10
^-^3, density is 1.395g/cm^3 or more, DSC
The peak temperature of the melting curve measured by
is 2.8 or more, birefringence is 50 x 10^-^3 or more, density is 1.140 g/cm^3 or more, and both the core component and sheath component have a highly oriented and highly crystalline fiber structure. Cord for reinforcing rubber hoses.