JPH0376661B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a low-temperature plasma treatment method for plain-woven tire cords, and particularly to a method for treating plain-woven tire cords using reinforcing materials such as polyester fibers and aromatic polyamide fibers. The purpose of the present invention is to provide a treatment method that improves the adhesion to rubber by subjecting objects to low-temperature plasma treatment, and which enables them to be used for tire processing immediately after plasma treatment. (Prior art) Conventionally, nylon, vinylon, rayon, etc. have been used as reinforcing materials for tire cord plain-woven materials, but polyester fibers, aromatic polyamide fibers, etc. have attracted attention as reinforcing materials with higher strength, and various Consideration has been made. However, although polyester fibers and aromatic polyamide fibers have excellent properties such as tensile strength, impact resistance, elongation resistance, dimensional stability, heat resistance, water resistance, chemical resistance, and weather resistance, However, it has poor adhesion to rubber and cannot provide sufficient strength as a tire reinforcing material. For this reason, various studies have been made to improve the adhesion to rubber, but a sufficient improvement effect has not yet been achieved. For example, JP-A No. 55-1393 discloses that a cord-like material made of twisted fibers such as polyamide fibers is treated with plasma to improve its adhesion. When weaving for molding, untreated areas are exposed on the surface due to a high degree of untwisting, etc., resulting in disadvantages that reduce the effectiveness of the treatment. This is due to the basic reason that the effect of plasma treatment only affects the surface, and in tire cords made of fine fibers twisted together, only the fibers on the surface of the cord are treated, and the parts hidden inside are treated. Since it is not treated, it has the disadvantage that untreated fibers are exposed to the surface due to high degree of untwisting. (Structure of the Invention) The present inventors have conducted extensive research in view of the above technical problems, and have found that by treating the surface of the plain woven tire cord with low-temperature plasma of an inorganic gas, the rubber of the plain woven tire cord can be The present invention was completed by confirming that the adhesion of the tire cord was significantly improved and that this low-temperature plasma-treated tire cord plain woven material could be immediately and continuously used for tire processing. That is, the present invention introduces an inorganic gas into a vacuum processing tank equipped with a discharge electrode inside to create a reduced pressure atmosphere of 0.001 Torr to 10 Torr, and while continuously passing a tire cord plain woven material between the electrodes. , a low-temperature plasma of the inorganic gas is generated by glow discharge, and the discharge voltage is 3000 V or more and the discharge current is 5.
This invention relates to a low-temperature plasma treatment method for a tire cord plain woven material, characterized in that the plain woven material is treated with a temperature maintained at . The density is from 20/5cm to 70/
The present invention relates to a blind-like plain weave structure in which the weft yarns are in the range of 5 cm and the weft yarns intersecting at right angles to the weft yarns are in the range of 2.0 yarns/5 cm to 6.0 yarns/5 cm. The present invention will be explained in detail below. The tire cord plain woven material targeted by the present invention is particularly preferably made of warp yarns twisted with polyester fibers or aromatic polyamide fibers, and the weft yarns of 20 to 30 counts or 50D (denier). )~250D thin thread is used, and the warp thread density ranges from 20 threads/5cm to 70 threads/
5cm, weft thread density from 2.0/5cm to 6.0/5cm
It is a woven fabric with a plain weave structure with a width of 100cm to 200cm and a number of stitches. The warp thread density is arbitrarily selected depending on the thickness and strength of the tire cord, but if the warp thread density is too low, it will be practically difficult to maintain the form of the fabric, and if it is too high, it will become difficult to maintain the shape of the fabric. If the warp cord spacing becomes narrow and rubber is coated after plasma treatment, the rubber will not penetrate between the cords, which is disadvantageous for adhesion, so the density must be within the above range. On the other hand, the weft yarn density needs to be within the above range for the purpose of preventing untwisting of the warp yarn cord and maintaining the flatness of the fabric, and if it is less than 2.0 threads/5 cm, untwisting of the cord cannot be suppressed. However, the weft yarns are likely to be cut during continuous treatment, making it difficult to stably obtain the desired treated fabric. Setting the number to 6.0 threads/5 cm or less is not preferable because it is not practically necessary to maintain the shape of the fabric, and it increases the contact area between the warp and weft threads, which is not affected by the low-temperature plasma treatment. . In addition, in the warp yarns of both edges of the fabric, two to two cords are alternately arranged in the S direction and the Z direction in the top weave direction.
It is preferable to insert 10 sets in order to prevent uneven processing due to curling of the ears during processing. Further, as described above, it is preferable for the weft used in the woven fabric to be a thin yarn of 20 to 30 count or 50D to 250D from the viewpoint of adhesion. Cords used for warp yarn are usually coated with a so-called cord oil at the stage of manufacturing the yarn, but if too much oil adheres, it will not only disturb the atmosphere of the plasma treatment but also produce by-products, resulting in adhesion. Not good. Therefore, it is preferable that the amount of oil applied to the cord used is 1.0% or less. As described above, it is desirable to use polyester fibers or aromatic polyamide fibers as the cords constituting the plain woven material, and examples of the aromatic polyamide fibers include polyparaphenylene terephthalamide, polymethaphenylene terephthalamide, Examples include fibers such as polyparabenzamide. The method of low-temperature plasma treatment of tire cord plain-woven materials involves introducing an inorganic gas into a vacuum treatment tank equipped with a discharge electrode inside the tank to create a reduced pressure atmosphere of 0.001 Torr to 10 Torr, and treating tire cord plain-woven materials between the electrodes. This is carried out by generating a low-temperature plasma of the inorganic gas by causing a glow discharge while passing an object continuously. Plasma discharge methods can be broadly classified into external electrode type, afterglow type, internal electrode type, etc., but in order to exert the treatment effect as far inside the plain woven material as possible and to achieve the effect in a short time, it is necessary to , which is equipped with electrodes inside the processing tank, and the pressure of the gas atmosphere inside the processing tank is as above.
A range of 0.001 Torr to 10 Torr is desirable. Inorganic gases introduced into the vacuum processing tank include helium, neon, argon, nitrogen, oxygen, air,
Examples include nitrous oxide, nitric oxide, nitrogen dioxide, carbon monoxide, and carbon dioxide.
The types are not limited, and two or more types may be mixed and used. Oxygen plasma is particularly effective for the purpose of the present invention, and therefore it is desirable to use oxygen gas or a gas containing at least 10% by volume of oxygen gas as the inorganic gas. Incidentally, an organic compound gas may be mixed with these inorganic gases, but the mixing ratio should be kept to a small amount. The conditions for performing glow discharge include, for example, keeping the inside of the vacuum processing tank at a reduced pressure in the range described above, and applying a frequency of 10KHz to 10KHz between the input electrode and the earth electrode.
It is sufficient to apply a power of 10W to 100KW at a high frequency of 100KMHz, which allows stable glow discharge to occur. Note that, in addition to the above-mentioned high frequency, low frequency, microwave, or direct current can be used as the discharge frequency band. If the gas pressure in the treatment tank is 10 Torr or more, the temperature rise during glow discharge will be significant, and the surface of the plain woven material to be treated may be altered and the treatment effect may be impaired, so it is not preferable; In this case, glow discharge is unstable and it is difficult to perform normal processing. Note that a discharge voltage and a discharge current are generated between the electrodes during discharge, and in order to make the treatment effect more noticeable, it is necessary to adjust the discharge voltage to 3000 V or more and the discharge current to a range of 5 to 30 A. The preferred treatment time for plain woven materials is from several seconds to several tens of seconds, which effectively imparts adhesive properties. There are no particular restrictions on the structure of the electrodes installed in the vacuum processing tank, and various structures such as rod-like, flat-plate, and ring-like structures can be used, but in order to eliminate thermal effects, internally cooled Preferably, electrodes are used. The material of the electrode is preferably copper, iron, aluminum, stainless steel, etc. In order to maintain stable low-temperature plasma, the input electrode is often provided with an insulating coating having a withstand voltage of 10,000 V/mm or more. Preferable coating materials include enamel coat, glass tube coat, and ceramic coat. As with the input electrode, the grounding (earth) electrode may be made of copper, iron, aluminum, or stainless steel and may have any structure or shape such as a rod, flat plate, or drum, but there is no particular need to coat the surface. For example, the inner wall of the metal processing tank may be used as the ground electrode. In any case, it is preferable that the ground-side electrode be sufficiently cooled to eliminate the thermal effects of discharge. The distance between the input electrode and the ground electrode is preferably 1 to 30 cm, preferably 3 to 15 cm, and 30 cm or more in order to stably perform glow discharge and provide sufficient adhesiveness to the plain woven material. This makes it difficult to synchronize the power input such as high frequency, making it impossible to stably supply sufficient power, and the effect of imparting adhesive properties is also small. On the other hand, if the distance is too small, the thermal influence will be large and the surface of the plain woven material will change in quality. Specific embodiments of treating the plain woven material by the method of the present invention are as shown in each drawing. FIG. 1 is a sectional view schematically showing a low-temperature plasma processing apparatus for carrying out the method of the present invention. In the figure, 1 is a vacuum processing tank, 2 and 2' are drum-shaped ground electrodes, and 3
indicates an input electrode. The wound plain woven material 4 passes through a drive roller 5 and a vacuum chamber 6, enters the vacuum processing tank 1 , moves sequentially over the surfaces of the ground electrodes 2 and 2', and undergoes low-temperature plasma treatment on both sides. After this, it passes through a vacuum chamber 6' and a driving roller 5' and is wound up as a roll 4'. Instead of winding it up as a roll 4', it can also be directly used for tire processing. 2, 3, and 4B schematically illustrate different devices, and 11 in FIG.
is a vacuum processing tank, 12 is a ground electrode, 13 is an input electrode, 21 in Fig. 3 is a vacuum processing tank (used at the same time as a ground electrode), 22 is input power, 31 in Fig. 4 B is a vacuum processing tank , 32 represents a ground electrode, and 33 represents an input electrode, respectively. Note that FIG. 3 shows a case where a plain woven material passes between input electrodes arranged in two rows and is subjected to low-temperature plasma treatment. Figure 4A shows an external electrode type device.
41 is a vacuum processing tank, and 42 is a high frequency coil. Next, a specific example will be given. Example 1 [Preparation of plain woven tire cord] 1500d/2 (40Z x 40S times/10cm) polyester cord was used as warp thread, warp thread density was 50 threads/5cm,
The weft yarn density is 4.0 threads/5cm and the number of strokes is
A plain woven tire cord with a width of 160 cm was produced using 30 count polynosic yarn. [Low-temperature plasma treatment] The plain woven material was subjected to low-temperature plasma treatment using the apparatus shown in FIG. That is, O ₂ gas is introduced into the vacuum processing tank at a rate of 2/min, the pressure inside the tank is maintained at 0.1 torr by reducing the pressure, and while the plain woven material is continuously passed between the electrodes, 110KHz is applied to the input electrode. ,
Low-temperature plasma treatment was performed by applying 40KW of power and causing glow discharge. A glass tube coated rod-shaped electrode was used as the input electrode, and a water-cooled drum electrode was used as the ground electrode placed at a distance of 5 cm, and the plain woven material was processed while passing over this drum electrode. The time that the plain woven material stayed between the electrodes was 10 seconds, and the discharge voltage and discharge current generated between the electrodes were respectively
It was 5.5KV, 20A. Discharge voltage and discharge current: When measuring high frequency output, the output voltage is measured by a voltage divider - rectifier - DC voltmeter circuit and the peak value of the output voltage is measured, and the output current is measured by a current transformer - current/voltage converter - DC voltmeter circuit. By providing this circuit, the effective value of the output current is measured. (In a current/voltage converter, the heater is heated by the input current, and the temperature of the heater, which rises in proportion to the input current, is detected by a thermocouple and converted to mV. Therefore, the measured current shows the effective value. ) Comparative Example 1 When plasma treatment was carried out in the same manner as in Example 1 except that the pressure in the vacuum treatment tank was maintained at 20 Torr and discharge was performed, the surface of the plain woven material became slightly hard, and Example 1 Adhesion to rubber was lower than in the case of . Example 2 A plain woven material was produced in the same manner as in Example 1 using 1500d/2 (30Z x 30S times/10cm) polyparaphenylene terephthalamide multifilament,
A low temperature plasma treatment was performed using the apparatus shown in FIG.
In other words, O ₂ 2/min, Ar 3/min in the vacuum treatment tank
/min, the inside of the tank was maintained at 0.5 torr, and while the plain woven material was passed continuously between the electrodes, high-frequency power of 13.56 MHz and 5 KW was applied to the input electrode to cause glow discharge, resulting in low-temperature plasma treatment. . Note that a hollow-coated flat plate type electrode was used as the input electrode, and a water-cooled drum electrode was used as the ground electrode placed at a distance of 10 cm, and the plain woven material was processed while passing over this drum electrode. The time the plain woven material stayed between the electrodes was 50 seconds, and the discharge voltage and discharge current generated between the electrodes were respectively
It was 4.0KV and 15A. Example 3 A plain woven material produced in the same manner as in Example 1 was
Low-temperature plasma treatment was performed using the apparatus shown in the figure. That is, O ₂ is introduced into the vacuum treatment tank at a rate of 1/min and N ₂ is introduced at a rate of 1/min, the inside of the tank is maintained at 0.2 Torr, and the plain woven material is continuously passed between the input electrodes.
Low-temperature plasma treatment was performed by applying a power of 110 KHz and 20 KW to cause glow discharge. The input electrodes were five glass tube-coated rod-shaped electrodes arranged vertically and in parallel at intervals of 10 cm, and the inner wall of the processing tank was used as a ground electrode, and the plain woven material was processed while passing between the input electrodes. The residence time between the electrodes was 50 seconds, the discharge voltage at this time was 4.0KV, and the discharge current was 25A. Example 4, Comparative Example 2 A plain woven material produced in the same manner as in Example 2 was subjected to low temperature plasma treatment using the apparatus shown in FIG. 4 A (Comparative Example 2) or B (Example 4) and compared. In either case, O ₂ was introduced into the vacuum treatment tank at a rate of 100ml/min to
A low temperature plasma was generated and processed by maintaining the temperature at 0.7 Torr and applying a power of 110 KHz and 2 KW.
In the case of the apparatus shown in Figure 2, the distance between the electrodes was 5 cm, and cooled flat plate electrodes were used for both electrodes. In either case, the plasma treatment time was 3 minutes, and the discharge voltage and discharge current generated between the electrodes were 3.3KV and 3.3KV, respectively.
It was 18A. Warp threads (tire cords) were collected from the plain woven fabrics subjected to plasma treatment in Examples 1 to 4, Comparative Example 1, and Comparative Example 2 described above, and cords not subjected to plasma treatment were collected for comparison. The cords were sampled and embedded in rubber compositions A and B shown below with a cord length of 8 mm and vulcanized at 150°C for 30 minutes.The adhesion strength was examined in a pull-out test to measure the force with which the cord was pulled out from the vulcanized rubber. Table 1 shows the results. As can be seen from this data, the adhesiveness of the method of the present invention was clearly improved compared to the untreated cord and the comparative example cord, and the rubber composition contained hexamethylenetetramine (formalin donor) and resorcinol (acceptor). ) (rubber composition B), even better adhesion can be obtained. [Rubber composition A] NR (RSS#3) 70 parts by weight SBR 1500 20 IR 2200 10 Zinc white 5 Stearic acid 2 Carbon black (GPF) 50 Poly(2,2,4-trimethyldihydroquinoline) 2 Paraffin oil 5 Sulfur 3 N-cyclohexyl-2-benzothiazyl sulfenamide 1 [Rubber composition B] NR (RSS#1) 100 parts by weight Zinc white 5 Stearic acid 3 Carbon black ( HAF) 40 Hydrous silicic acid 10 Poly(2,2,4-trimethyldihydroquinoline) 1 Paraffin oil 5 Resorcinol 3 Hexamethylenetetramine 2 Sulfur 3 N-oxydiethylene-2-benzothiadylsulfate Phenamide 0.5 〃 [Table]

[Brief explanation of drawings]

Figures 1, 2, 3, and 4B schematically show a low-temperature plasma processing apparatus for carrying out the method of the present invention, and Figure 4A shows a diagram for comparison. 1 schematically shows a processing device. 1 ... Vacuum processing tank, 2, 2'... Drum type ground electrode, 3... Input electrode, 4... Plain woven material, 4'...
...Low temperature plasma treated plain woven material, 5,5'...
...Drive roller, 6,6'...Vacuum chamber.

Claims (1)

[Claims] 1 Inorganic gas is introduced into a vacuum processing tank equipped with a discharge electrode inside to create a reduced pressure atmosphere of 0.001 Torr to 10 Torr. Between the electrodes, a large number of cords are arranged in the longitudinal direction, and their density is 20 Torr. Book/70 from 5cm
Glow discharge is carried out while continuously passing through a tire cord plain-woven material with a blind-like plain-woven structure in which the weft yarns are in the range of 2.0 yarns/5 cm to 6.0 yarns/5 cm and are intersected at right angles. A low-temperature plasma treatment method for a plain-woven tire cord material, comprising: generating low-temperature plasma of the inorganic gas, and treating the plain-woven material by maintaining a discharge voltage of 3000 V or more and a discharge current of 5 to 30 A.