JP2005343685A - Connection method for tire cord - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection method for a tire cord for connecting two cords in a short time by a simple method and letting them pass smoothly in a process without causing cord cutting. <P>SOLUTION: End parts 11a, 12a of two cords are arranged in a butting manner, an outer peripheral part of the cord including a butting part 14 is covered with unvulcanized rubber 2, and then a rubber covered layer 3 is vulcanized and molded in a channel of a mold with a channel having predetermined channel inside diameter to form a connection part 13 and connect the tire cord 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tire cord connecting method for connecting two cord ends.

  As a reinforcing material for the carcass layer and belt layer of pneumatic tires, use a topping sheet that aligns the tire cords without using wefts and is covered with rubber to improve the weight and uniformity of the tires. It has been practiced to improve the high-speed durability by forming a reinforcing layer of the belt layer by spirally winding in the tire circumferential direction.

As a single tire cord used for such an application, a tire cord that is elongated by connecting a short cord is used, and continuous operation of the process is achieved. Various methods have been proposed in the past for connecting the connecting cords so that the connecting portions of the connecting cords can pass through the process smoothly without causing cord breakage in a production line such as a die process (Patent Documents 1 and 2).
JP 2003-247129 A JP 2003-301340 A

  However, the technique described in Patent Document 1 connects the base yarn through an auxiliary yarn having a thickness of ½ or less of the base yarn, and high pressure air is blown onto the overlapping portion of the auxiliary yarn and the base yarn. It is necessary to entangle each other. Further, the technique described in Patent Document 2 is to divide both ends of the fiber yarn into a plurality of portions once, and entangle the yarns by the number of divided portions equal to the divided number to join the yarns. This requires a complicated work of air entanglement of the divided portions, and in any case, it is necessary to prevent the yarn at the entangled portion from loosening, and skill in connecting the yarn is required.

  The present invention is a tire cord connection method that can connect two tire cords in a simple manner to make the tire cord long, and in a production line having a dice process having a limited diameter, etc. It is an object of the present invention to provide a tire cord connecting method that allows a tire cord that has been used to pass smoothly without causing a cord break or the like in the process.

  The present invention relates to a tire cord connecting method, characterized in that two cord end portions are arranged in abutting manner, a rubber coating layer covering the outer periphery of the cord including the abutting portion is vulcanized and a tire cord is connected. It is.

  According to the tire cord connecting method of the present invention, the cord outer periphery including the butting portion is covered and connected with the rubber coating layer formed by vulcanization so that the cord is untwisted or the cord shape of the connecting end is changed. Manufacture tire cords that are easy to pass through without the need for skill and without troublesome work such as trimming and air entanglement, and without causing protrusions and filaments to jump out of the cord connection part be able to.

  In the present invention, in the abutting portion, the cord ends are arranged in a non-contact manner, so that the rubber filled in the non-contact space portion shows the connection strength of the cord, and the strength of the cord connection portion is increased. Can be increased.

  In the tire cord connection method of the present invention, the outer peripheral portion of the cord including the abutting portion is coated with unvulcanized rubber, and then the rubber coating layer is vulcanized in a groove of a grooved mold having a predetermined groove shape. By connecting the tire cord, it is possible to easily form a rubber coating layer having a predetermined cross-sectional shape that improves processability by vulcanizing operation in the mold, and to stabilize the processability of the connection cord. it can.

  In this case, since the grooved mold has a plurality of grooves, a plurality of tire cords can be connected at the same time, and the cord connection efficiency can be improved.

  The outer diameter of the rubber coating layer is preferably in the range of 1.05 to 1.20 times the tire cord body diameter, and the cord connecting portion is cut by a dicing process or a grooved roll or derailed from the groove. Preventing and securing process passability.

Then, by the 0.99 ° C. T ₉₀ of vulcanized rubber composition forming the rubber coating layer is within 3 minutes, it is possible to improve the work efficiency and shortening the work time required for cable connection.

  According to the tire cord of the present invention, in a production line having a dice process or the like having a limited diameter, it is possible to smoothly pass a connected tire cord without causing a cord break or the like in the process. This tire cord can be easily obtained, and an infinite length tire cord can be obtained by repeating the connection at the end of the cord. As a result, in the topping process of a single cord using an extruder or a calendar device, troubles such as cord breakage can be prevented and continuous operation can be performed, and the production efficiency of a topping sheet without weft is remarkably improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1-8 shows the tire cord 1 which concerns on embodiment of this invention, and an example of the connection method.

  As the tire cord used in the present invention, organic fiber cords such as polyester, nylon, aramid, rayon and the like are suitable, and two tires represented by 1100 dtex / 2, 1670 dtex / 2, 1670 dtex / 3, etc. composed of a large number of filaments. A twisted or triple twisted cord that has been subjected to an adhesive treatment with an RFL treatment liquid and a heat treatment is used.

  Here, the tire cord 1 shown in the drawing is a tire cord having a two-strand structure (for example, 1670 dtex / 2), the two cord ends 11a and 12a of the two cords 11 and 12 are butted against each other, and the butted portion 14 is formed. The rubber coating layer 3 is formed on the outer peripheral portions on both sides in the cord axial direction with the butting portion 14 as a center to form the cord connecting portion 13, which is a single continuous tire cord.

  That is, as shown in FIG. 2, after covering the outer peripheral portions on both sides in the cord axis direction with the unrubber layer 2 around the butting portion 14, the unvulcanized rubber layer 2 is vulcanized as shown in FIG. 3. The cylindrical rubber coating layer 3 along the outer periphery of the cord is vulcanized and molded, and the rubber coating layer 3 is vulcanized and bonded to the outer periphery of the cords 11 and 12 so that the two cords 11 and 12 are connected. Is.

  Since the butt portion 14 is accommodated in the vulcanized rubber layer 3, the cord connection portion 13 prevents the stepped portion of the butt portion 14 and the whiskers of the filaments unraveled from the end portion of the cord. The passability can be maintained well. In the figure, the unvulcanized rubber layer 2 and the vulcanized rubber coating layer 3 are shown in a transparent state for convenience.

  Both cord end portions 11a and 12a of the cords 11 and 12 forming the abutting portion 14 are end portions 11b and 12b (FIG. 4 (a)) cut at an inclination with respect to the cord axis as shown in FIG. Further, the end portion may be a filament 11c, 12c (same (b)), and both end portions may have different shapes and cross sections. In the present invention, as described above, It is possible to eliminate the failure of the connecting portion due to the irregular cross-sectional shape of the cord end.

  In the tire cord connection method of the present invention, the cord end portions 11a and 12a may be arranged in a non-contact state 14a as shown in FIG. Thereby, the rubber filled in the non-contact space portion 14a by vulcanization becomes continuous with the rubber coating layer 3 on the outer periphery of the cord and shows the connection strength of the cord 1, and the cord end portions 11a and 12a come into contact with each other. The connection strength can be increased as compared with the case where no rubber is interposed.

  The length of the non-contact portion is about 0.3 to 2.5 mm. If this length is too long, a difference in rigidity occurs in the cord axis direction, which may cause a process trouble based on the difference.

  The connecting portion 13 covered with the unvulcanized rubber 2 can be vulcanized in a mold to vulcanize and mold the rubber coating layer 3. Further, the rubber coating layer 3 can be formed by vulcanization by irradiation with high frequency, electron beam or radiation.

  In the case of mold vulcanization, a grooved mold having a predetermined groove shape is used, and the cord connecting portion 13 covered with the unvulcanized rubber layer 2 is vulcanized in the groove to vulcanize and mold the rubber coating layer 3. It is preferable because the outer shape of the rubber coating layer 3 and the vulcanization speed are stabilized to facilitate the connection of the tire cord 1. In addition, what is necessary is just to remove the burr | flash produced in the case of this vulcanization operation with a soot.

  The groove of the grooved mold is preferably a linear groove having a predetermined cross-sectional shape, preferably a circular cross-section, and the connecting portion 13 is smooth when passing through a die hole or a grooved roll. Process passability can be improved.

  In the case of this mold vulcanization, since the grooved mold has a plurality of grooves, a plurality of tire cords can be connected simultaneously, and the connection efficiency of the cords can be improved.

  Further, the outer diameter of the cord connecting portion 13 is set so that the cord connecting portion prevents the cord from being cut or derailed from the groove in a dicing process or a grooved roll and the like so as to ensure process passability. It is preferably in the range of 1.05 to 1.20 times. What is necessary is just to adjust the coating | coated thickness of the unvulcanized rubber 2, the groove shape of a grooved mold, and an internal diameter so that it may adapt to the outer diameter range of this connection part 13. FIG.

  In the present invention, the method for forming the coating layer of the unvulcanized rubber 2 on the outer peripheral portion around the butted portion 14 is not limited at all, and as shown in FIG. 12 wraps the rubber sheet 2a along the axial direction, 12 wraps the ribbon-shaped rubber sheet 2b while overlapping one side as shown in FIG. 7, and two rubber sheets 2c and 2d as shown in FIG. The method of pinching from both sides of the cord is mentioned. In the case of vulcanization molding of a grooved mold, the method shown in FIG. 8 is the simplest, and a method in which a rubber sheet 2c is laid on the mold side and a cord is arranged to cover the rubber sheet 2d can be adopted. The connecting portion 13 can be finished in a predetermined shape by simply removing the burrs after vulcanization.

  The length of the rubber coating layer 3 is about 5 to 20 times the cord diameter on one side of the abutting portion 14, and the length depends on the cord structure such as the cord material and diameter and the blending prescription of the rubber material. The strength can be determined as appropriate in consideration of the strength of 13 and workability.

In addition, the rubber composition used for the rubber coating layer 3 of the present invention preferably has T _{90 in} vulcanization at 150 ° C. within 3 minutes, shortening the vulcanization time required for cord connection and improving work efficiency. Of course, in the cord preparation work process, the cord connection in the middle of the tire production line is possible in a short time, and the production efficiency is not lowered.

Thus, to shorten the pressure of the rubber coating layer 3 vulcanization is the T ₉₀ as 3 minutes or less, a diene rubber such as natural rubber and the rubber component, 30 to 50 parts by weight of HAF grade carbon black, sulfur A blending formulation such as 1 to 3 parts by weight and 0.2 to 3 parts by weight of a dithiocarbamate vulcanization accelerator may be employed. T ₉₀ is measured by a vulcanization tester such as a rheometer or a curast meter.

  As a result, the coating layer of the unvulcanized rubber 2 adheres to the outer peripheral portions of the cords 11 and 12 by vulcanization at both side portions of the cord abutting portion 14, and bites into the cord twists to exhibit the anchoring effect and It is possible to obtain the tire cord 1 in which the connecting portion 13 is formed by the vulcanized and bonded rubber coating layer 3.

  Further, the tensile strength of the connecting portion 13 is secured to 50% or more, preferably 60% or more of the tensile strength of the main body cord to prevent cord breakage due to catching or cord tension during topping. If the cord connecting portion 13 has sufficient durability, it may be incorporated into the product tire as it is. If the durability is insufficient, the connecting portion 13 may be removed and used. Whether or not the connecting portion 13 can be used in a tire can be determined based on the use as a strength member such as a carcass and the use or part as a rigid member such as a belt reinforcing layer.

  In addition, by setting the outer diameter of the connecting portion 13 in the above range, the topping sheet surface does not bulge or dent, and not only improves the appearance of the seat but also improves tire performance such as uniformity. can do.

  The tire cord 1 obtained in this manner is further lengthened by repeating this connection, and can be made into an infinite length tire cord, which is passed through a die hole or a ridge opened in the base. By arranging a plurality of lines at a predetermined pitch by means such as supplying to an extruder or calender device and topping the rubber, process troubles such as cord breakage and derailment from the calender roll groove occur during processing. Thus, a long topping sheet having no weft can be obtained.

  Further, the tire cord 1 is directly wound around the tire circumferential direction at an angle of approximately 0 ° in the tire molding process, and the tire cord 1 is covered with a tread or a side rubber to be vulcanized and integrated, so that It can be used as a reinforcing cord for a belt reinforcing layer, a belt end reinforcing layer, a side reinforcing layer or the like that does not cause a joint portion in the direction.

  EXAMPLES The present invention will be further described below with reference to examples, but it goes without saying that the present invention is not limited to these examples.

  The cords of Examples and Comparative Examples in which connection portions were formed according to the following connection method using a treated tire cord of polyester 1670 dtex / 2 (twist number 38 × 38 times / 10 cm, cord diameter 0.65 mm), The working time required for connection, the outer diameter (maximum diameter) and tensile strength of the connection part were measured in accordance with JIS L1017. The working time is 100 in Example, and the outer diameter and tensile strength are shown in Table 1 in index notation with Comparative Example 4 being 100.

The formulation of the rubber composition used in the examples is as follows. 100 parts by weight of natural rubber (RSS # 3), 45 parts by weight of carbon black (“N330” manufactured by Tokai Carbon Co., Ltd.), 2.5 parts by weight of sulfur (manufactured by Shikoku Kasei), vulcanization accelerator (“Noxeller manufactured by Ouchi Shinsei Chemical Industry) PZ ") 2.5 parts by weight, zinc white (Mitsui Metals" Zinc Flower 1 ") 2 parts, stearic acid (manufactured by Nippon Oil & Fats) 2 parts by weight, anti-aging agent (Monsanto" 6PPD ") 1 part by weight . T ₉₀ of the rubber composition after vulcanization at 150 ° C. is 2 minutes as measured by a rheometer manufactured by Monsanto.

[Connection method]
Example 1: A cord abutting portion with which both end portions are in contact is sandwiched from above and below with an unvulcanized rubber sheet having a thickness of 0.7 mm, a width of 4 mm, and a length of 20 mm as shown in FIG. Using a split mold having a linear groove (diameter 0.75 mm), vulcanization was carried out at 150 ° C. for 2 minutes to form a connecting portion by a rubber coating layer shown in FIG.
-Example 2: As shown in FIG. 5, a non-contact part having a width of 1 mm is provided in the cord abutting part, and the non-contact space part shown in FIG. 5 is filled with rubber in the same manner as in Example 1. Formed.

Comparative Example 1: Both ends of the cord were overlapped with a length of 20 mm, and the overlapped portion was pressure-bonded in the grooved mold at 150 ° C. to form a connection portion by welding.
Comparative Example 2: A cyanoacrylate-based one-pack type instantaneous adhesive (Aron Alpha 201 manufactured by Toa Gosei Co., Ltd.) was applied to the cord abutting portion, and both ends of the cord were bonded together to form a connection portion.
Comparative Example 3: A 15 mm length of each cord end was broken into filaments, and a connection portion was formed by an air joint method.
-Comparative example 4: It is a main body code | cord | chord which does not include a connection part.

  Next, as shown in the schematic diagram of the interior 9 of the extruder head of FIG. 9, using a single cord of each example and comparative example including a connecting portion every 200 m on average, a large number of cords 91 are arranged at a constant pitch. A topping device having a base 93 having a harmonica-shaped die hole 95 through which a cord for arrangement is inserted, a base 92 for determining the rubber thickness of the topping sheet, and an extruder (not shown) for supplying topping rubber is used. Then, it was processed into a topping sheet 94 having a cord driving density of 23/25 mm, a topping thickness of 1.1 mm, and a sheet width of 10 cm.

  The processability of each cord through the die hole 95 (hole diameter 0.8 mm) in this topping process was evaluated. There is no cord breakage and there is no problem in the process passability, and no code breakage occurs, but there is a code runout when passing through the connecting part, resulting in a partial end number disorder in the topping sheet and a slight change in process passability Table 1 shows “△” when there is a problem and “x” when code breakage frequently occurs and cannot be used.

  Further, using the single cords of the examples and comparative examples including the connecting portion every 100 m on average, the belt is formed by winding the cord in a spiral shape in the tire circumferential direction with a secondary molding machine of a green tire (size, 205 / 60R15). In the step of forming the reinforcing layer, the passability of a grooved roll for supplying a single cord on the belt was evaluated. The roll groove has a V-shaped cross section, a maximum groove width of 0.9 mm, a groove depth of 0.3 mm, a roll outer diameter of 150 mm, and a cord tension of 300 g.

  The processability of each cord when it passes through a roll with a groove is “O” when there is no cord derailment from the groove and there is no problem with the processability, but there is no cord derailment, but cord runout occurs when it passes through the connection. Table 1 shows “Δ” when the end of the belt reinforcement layer is partially disturbed and there is a slight problem in process passability, and “x” indicates that the cord is derailed frequently and cannot be used.

  The cord connecting portions of Examples 1 and 2 have a tensile strength of 60% or more of the main body cord and an outer diameter within a predetermined range, and have good processability without causing any problems in processability. On the other hand, in Comparative Example 1 and Comparative Example 2, cord breakage occurs frequently when passing through the hole of the base due to insufficient strength of the connection part, and in Comparative Example 3, the connection part is caught in the hole of the base and end disturbance due to the shake of the cord is caused. Occurred. Further, the cord of Comparative Example 3 has a large outer diameter of the connecting portion, and frequent derailment from the grooved roll, resulting in poor process passability. It can be seen that the cord of the example in which the connecting portion according to the present invention is formed has a short working time to form the connecting portion and is excellent in process passage.

  The tire cord of the present invention is a single cord alone or by efficiently producing a weft-free topping sheet using a topping device such as an extruder, and the like for each part of a pneumatic tire such as a carcass, a belt, a belt reinforcing layer, and a sidewall. Can be used as a reinforcing material. Moreover, it can utilize also as reinforcing materials, such as industrial articles other than a tire, parts for vehicles, for example, a V belt, a conveyor belt, an air spring, and a flexible coupling for motor vehicles.

It is a front view which shows before the connection of the tire cord of embodiment. It is a schematic diagram explaining formation of a connection part same as the above. It is a front view which shows a connection part same as the above. It is a code front view which shows the state of a tire cord edge part. It is a code front view (rubber coating layer shows a section) which shows a connection part in which a code end is in a non-contact state. It is a code front view showing an example of formation of an unvulcanized rubber layer. It is a code front view showing other examples of unvulcanized rubber layer formation. It is a code front view showing other examples of unvulcanized rubber layer formation. It is the schematic which shows the inside of an extruder die.

Explanation of symbols

1,11,12..Tire cord 11a, 12a .... Cord end 2 .... Unvulcanized rubber 3 .... Rubber coating layer 13 ... Connecting part 14 ... Abutting part

Claims (6)

A tire cord connection method comprising: arranging two cord end portions in a butted manner, vulcanizing and forming a rubber coating layer covering a cord outer peripheral portion including the butted portion, and connecting the tire cord. The tire cord connection method according to claim 1, wherein in the abutting portion, the cord end portions are arranged in a non-contact manner. The outer periphery of the cord including the butt portion is coated with unvulcanized rubber, and then the rubber coating layer is vulcanized and connected to a tire cord in a groove of a grooved mold having a predetermined groove shape. The method for connecting tire cords according to claim 1 or 2. The tire cord connection method according to claim 3, wherein the grooved mold has a plurality of grooves. The tire cord connection method according to any one of claims 1 to 4, wherein an outer diameter of the rubber coating layer is in a range of 1.05 to 1.20 times a tire cord main body diameter. Connection method for tire cord according to claim 1, wherein the T ₉₀ at 0.99 ° C. vulcanized rubber composition forming the rubber coating layer is within 3 minutes.

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