JP2012158156A - Method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pneumatic tire the deterioration in the external appearance of which can be suppressed.SOLUTION: The pneumatic tire includes: a carcass which extends from a tread to beads of both sides via sidewalls and comprises a carcass ply obtained by covering an array 12 of carcass cords 11 with topping rubber 13; and an inner liner which is arranged additionally at the inside of the carcass and comprises air-impermeable rubber for forming an inner cavity face of the pneumatic tire. The method for producing the pneumatic tire comprises steps of: covering one-side S1 surface of the array 12 of carcass cords 11 with the first topping rubber 13A and covering the other-side S2 surface of the array 12 of carcass cords 11 with the second topping rubber 13B which has Mooney viscosity higher than that of the first topping rubber 13A to form a raw carcass ply 16; and sticking unvulcanized inner liner rubber to the side of the second topping rubber 13B of the raw carcass ply 16.

Description

  The present invention relates to a method for manufacturing a pneumatic tire capable of suppressing a decrease in tire appearance.

  Conventionally, a pneumatic tire is provided with an inner liner made of a low air permeability rubber such as butyl rubber on the inner surface of a carcass ply in which an array of carcass cords is covered with a topping rubber. Such an inner liner is useful for maintaining the tire internal pressure. Related literature includes the following (see Patent Document 1 below).

JP 2006-159944 A

  However, in the pneumatic tire as described above, the rubber flow during vulcanization causes a so-called open thread in which the inner liner enters between the array of carcass cords, and the yarn appearance appears, thereby impairing the tire appearance. was there.

  The present invention has been devised in view of the actual situation as described above. One surface of the carcass cord array is coated with a first topping rubber, and the other surface of the carcass cord array is covered with the first surface. Basically including a step of forming a raw carcass ply by coating with a second topping rubber having a Mooney viscosity larger than that of the topping rubber and a step of attaching an inner liner to the second topping rubber side of the raw carcass ply The main object of the present invention is to provide a method for manufacturing a pneumatic tire capable of suppressing deterioration of the tire appearance due to open threads or the like.

  According to the first aspect of the present invention, a carcass comprising a carcass ply in which an array of carcass cords is covered with a topping rubber and extends from a tread portion to a bead portion on both sides through a sidewall portion, A method of manufacturing a pneumatic tire comprising an inner liner made of air-impermeable rubber that is attached to an inner side and forms a tire lumen surface, wherein a surface on one side of the array of carcass cords is a first one. Covering the other side of the array of carcass cords with a second topping rubber having a Mooney viscosity greater than that of the first topping rubber to form a raw carcass ply, Pasting the uncured inner liner rubber to the second topping rubber side of the raw carcass ply. To.

  The invention according to claim 2 is the method for producing a pneumatic tire according to claim 1, wherein the raw carcass ply is bonded to the inner liner rubber without being irradiated with EBR.

  The invention according to claim 3 is the method for producing a pneumatic tire according to claim 1 or 2, wherein the raw carcass ply has a maximum thickness of 0.5 to 1.5 mm.

  According to a fourth aspect of the present invention, the Mooney viscosity of the second topping rubber is 110 to 200% of the Mooney viscosity of the first topping rubber. The pneumatic according to any one of the first to third aspects A tire manufacturing method.

  The invention according to claim 5 is the pneumatic tire according to any one of claims 1 to 4, wherein a minimum thickness of the second topping rubber to the carcass cord is 0.1 to 0.5 mm. It is a manufacturing method.

  A pneumatic tire manufactured by the manufacturing method of the present invention includes a carcass made of a carcass ply in which an array of carcass cords extending from a tread portion to a bead portion on both sides through a sidewall portion and covered with a topping rubber, and the inside of the carcass And an inner liner made of an air-impermeable rubber that forms the inner surface of the tire.

  In addition, the method for manufacturing a pneumatic tire covers one surface of the carcass cord array with the first topping rubber, and the other surface of the carcass cord array has a Mooney viscosity higher than that of the first topping rubber. A step of forming a raw carcass ply by covering with a large second topping rubber; and a step of attaching an inner liner to the second topping rubber side of the raw carcass ply.

  In such a pneumatic tire manufacturing method, since the inner liner is bonded to the second topping rubber side with less rubber flow, the inner liner is prevented from entering between the carcass cord arrays during vulcanization. In addition, deterioration of the tire appearance due to open threads or the like can be suppressed. Further, the first topping rubber disposed on the side having less influence on the open thread has a small Mooney viscosity, and has a relatively good rubber flow compared to the second topping rubber. Therefore, the first topping rubber has good processability at the time of kneading and molding, and helps to minimize the deterioration of productivity.

It is sectional drawing which shows the pneumatic tire manufactured by the manufacturing method of this embodiment. It is AA sectional drawing of FIG. It is sectional drawing explaining the process of bonding an unvulcanized inner liner rubber to a raw carcass ply. It is sectional drawing of a raw carcass ply.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a pneumatic tire 1 manufactured by the manufacturing method of the present embodiment includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to bead portions 4 on both sides, and the carcass 6. It is configured as a radial tire for a passenger car including a belt layer 7 disposed on the outer side in the tire radial direction and inside the tread portion 2, and an inner liner 9 attached to the inner side of the carcass 6 and forming the tire lumen surface 10s. ing.

  The carcass 6 is composed of at least one carcass ply 6A, in this embodiment, one carcass ply 6A. The carcass ply 6A is folded back from the inner side to the outer side in the tire axial direction around the bead core 5 extending from the main body 6a and extending from the main body 6a to the bead core 5 of the bead part 4 through the sidewall part 3 and the bead part 4. And the folded portion 6b.

  Further, a bead apex 8 made of hard rubber extending from the bead core 5 to the outer side in the tire radial direction is disposed between the main body portion 6a and the folded portion 6b, and the bead portion 4 is appropriately reinforced.

  Further, the carcass ply 6A is arranged at an angle of, for example, 80 to 90 degrees with respect to the tire equator C (shown in FIG. 1), as shown in an enlarged view in FIG. The carcass cord 11 includes an array 12 and a topping rubber 13 that covers both surfaces of the array 12. As the carcass cord 11, for example, an organic fiber cord such as polyester, nylon, rayon, or aramid is suitably employed.

  As shown in FIGS. 1 and 2, the belt layer 7 includes at least two belt cords 14 arranged at a small angle of, for example, 10 to 40 degrees with respect to the tire equator C, in this embodiment, the tire radius. Two belt plies 7A and 7B inside and outside are overlapped in the direction so that the belt cords 14 cross each other. Further, although a steel cord is employed for the belt cord 14 of the present embodiment, a highly elastic organic fiber cord such as aramid or rayon can also be used as necessary.

  The inner liner 9 is disposed in almost the entire region of the tire lumen surface 10s across the bead cores 5 and 5 in a toroidal shape. The inner liner 9 is made of, for example, air-impermeable butyl rubber containing 50 parts by weight or more of halogenated butyl in the rubber, and is useful for maintaining the tire internal pressure.

  In the pneumatic tire 1 of the present embodiment, as shown in FIG. 2, the topping rubber 13 of the carcass ply 6A is arranged on the tire outer surface side in the main body portion 6a of the carcass ply 6A. And a second topping rubber 13B disposed on the inner liner 9 side in the main body 6a and harder than the first topping rubber 13A. In the unvulcanized state, the second topping rubber 13B has a Mooney viscosity larger than that of the first topping rubber 13A.

  The Mooney viscosity is one of indices indicating rubber flowability during vulcanization of unvulcanized rubber. The smaller the Mooney viscosity, the better the rubber flow during vulcanization, and the higher the Mooney viscosity, the worse the rubber flow. Accordingly, the second topping rubber 13B has less rubber flow during vulcanization than the first topping rubber 13A. Therefore, in the pneumatic tire 1 of the present embodiment, the rubber of the inner liner 9 plasticized during vulcanization molding is prevented from moving by the second topping rubber 13B having a small rubber flow because the Mooney viscosity is large, and the carcass cord Entry between 11 is suppressed. Therefore, the pneumatic tire of the present embodiment can effectively prevent deterioration of the tire appearance due to open threads or the like.

  Further, the first topping rubber 13A has a small Mooney viscosity, and has a relatively good rubber flow compared to the second topping rubber. Therefore, the first topping rubber has good workability during kneading and molding, and deterioration of workability and productivity due to the use of the second topping rubber 13B can be minimized.

  As shown in FIG. 3, such a tire 1 includes a step of forming a sheet-like raw carcass ply 16 (hereinafter referred to as “raw carcass ply forming step”), a raw carcass ply 16, an inner liner rubber 17, and the like. And a step of bonding (hereinafter referred to as “bonding step”).

  In the raw carcass ply forming step, as shown in an enlarged view in FIG. 4, the surface of one side S1 of the array 12 of the carcass cord 11 is covered with a sheet-like first topping rubber 13A, and the array The surface of the other side S2 of 12 is covered with a second topping rubber 13B having a Mooney viscosity M2 which is larger than the Mooney viscosity M1 of the first topping rubber 13A, whereby the raw carcass ply 16 is formed. The first topping rubber 13 </ b> A and the second topping rubber 13 </ b> B can be attached to the array body 12 at the same time by using, for example, a biaxial extrusion topping device, and the boundary surface thereof is substantially the carcass cord 11. Can be located on the center line of the array.

  According to the Mooney viscosity test described in JIS K6300 “Physical test method for unvulcanized rubber”, the “Mooney viscosity” is L-shaped and preheated at 130 ° C. for 1 minute. Is a value measured after rotating for 4 minutes.

  In the bonding step, as shown in FIG. 3, first, a sheet-like inner liner rubber 17 is wound around the outer peripheral surface of the molding drum 20, and the raw carcass ply 16 is placed outside the inner liner rubber 17. The second topping rubber 13B (shown in FIG. 4) is bonded to the inner liner rubber 17 side. In the present embodiment, unvulcanized raw chafer rubber 21 is disposed on both outer edges of the inner liner rubber 17 in the drum axial direction.

  Although not shown, a bead core setting step of inserting a bead core and a raw bead apex rubber into a carcass winding body 18 including a raw carcass ply 16 and an inner liner rubber 17 as in a conventional manufacturing method, the carcass A bulging step for bulging the wound body 18 in a toroidal shape, a joining step for pressing the tread ring against the carcass wound body 18 to form a green tire, and a vulcanization molding of the green tire with a vulcanization mold The tire 1 of FIG. 1 is manufactured through the sulfurization process. And in the said raw tire, since the inner liner rubber 17 is affixed facing the 2nd topping rubber 13B with little rubber flow at the time of a vulcanization, as mentioned above, the carcass cord 11 in a vulcanization process is carried out. Intrusion between the array bodies 12 is suppressed.

  In order to effectively exhibit the above action, the Mooney viscosity M2 of the second topping rubber 13B is preferably 110% or more, more preferably 120% or more of the Mooney viscosity M1 of the first topping rubber 13A. When the Mooney viscosity M2 becomes small, there is a possibility that the above-described effects cannot be sufficiently exhibited. Conversely, when the Mooney viscosity M2 increases, a large rigidity step is formed between the first and second topping rubbers 13A and 13B after vulcanization, and the durability performance may be reduced. From such a viewpoint, the Mooney viscosity M2 is preferably 200% or less, more preferably 180% or less of the Mooney viscosity M1.

  From the same viewpoint, the Mooney viscosity M2 of the second topping rubber 13B is preferably 45 or more, more preferably 50 or more, and preferably 80 or less, more preferably 75 or less. Further, the minimum thickness W1 of the second topping rubber 13B to the carcass cord 11 is preferably 0.1 mm or more, more preferably 0.15 mm or more, and preferably 0.5 mm or less, more preferably 0. .4mm or less is desirable.

  In the manufacturing method according to the present embodiment, as described above, it is possible to effectively prevent a decrease in tire appearance due to an open thread or the like, and therefore, the maximum thickness W2 of the raw carcass ply 16 is formed to be smaller than that in the related art. Can do. Thereby, since the raw carcass ply 16 can reduce the amount of rubber | gum of the topping rubber 13, it can reduce tire mass and manufacturing cost.

  The maximum thickness W2 of the raw carcass ply 16 is preferably 0.5 mm or more, and more preferably 0.7 mm or more. When the maximum thickness W2 is reduced, the rigidity of the carcass ply 6A (shown in FIG. 1) is excessively reduced, and the durability performance may be reduced. Conversely, if the maximum thickness W2 is increased, the tire mass may be excessively increased. From such a viewpoint, the maximum thickness W2 is preferably 1.5 mm or less, and more preferably 1.3 mm or less.

  Further, the raw carcass ply 16 can effectively prevent the inner liner rubber 17 from entering during vulcanization. For this reason, it is preferable that the raw carcass ply 16 is bonded to the inner liner rubber 17 without irradiating the raw carcass ply 16 with an electron beam in advance and performing EBR irradiation that is vulcanized or semi-vulcanized. Thereby, the manufacturing method of this embodiment can suppress the increase in a manufacturing process and the enlargement of a manufacturing facility, and can suppress manufacturing cost significantly.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

Pneumatic tires having the basic structure shown in FIG. 1 were manufactured according to the manufacturing method of the present invention with the specifications shown in Table 1, and their performance was evaluated. For comparison, pneumatic tires (Comparative Example 1 and Comparative Example 2) made of one type of topping rubber were also manufactured and tested in the same manner. The common specifications are as follows.
Tire size: 215/45 R17
Rim size: 17 × 7J
The test method is as follows.

<Tire appearance>
After manufacturing each test tire, the open thread was visually observed and evaluated by a five-point method. A larger value indicates that open threads can be prevented and the appearance of the tire is better.

<Manufacturing cost>
The manufacturing cost required to manufacture one tire is indicated by an index with Comparative Example 1 as 100. The smaller the numerical value, the smaller the manufacturing cost and the better.

<Tire mass>
The mass per pneumatic tire was measured. The smaller the value, the better.

<Durability>
Each test tire was assembled on the rim, filled with an internal pressure of 200 kPa, and run on a drum tester at a speed of 80 km / h, and the running distance until the tire broke was examined. In the evaluation, the travel distance was displayed as an index with Comparative Example 1 as 100. The larger the value, the better.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tire manufactured by the manufacturing method of the example can suppress deterioration of the tire appearance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 6 Carcass 6A Carcass ply 9 Inner liner 11 Carcass cord 12 Array 13 Topping rubber 13A First topping rubber 13B Second topping rubber 16 Raw carcass ply

Claims (5)

A carcass made of a carcass ply in which an array of carcass cords is covered with a topping rubber, from the tread portion to the bead portion on both sides through the sidewall portion,
A pneumatic tire manufacturing method comprising an inner liner made of air-impermeable rubber that is attached to the inside of the carcass and forms a tire lumen surface,
A surface on one side of the array of carcass cords is covered with a first topping rubber, and a surface on the other side of the array of carcass cords has a Mooney viscosity higher than that of the first topping rubber. Forming a raw carcass ply by covering with rubber;
And a step of bonding an unvulcanized inner liner rubber to the second topping rubber side of the raw carcass ply.   The method of manufacturing a pneumatic tire according to claim 1, wherein the raw carcass ply is bonded to the inner liner rubber without being irradiated with EBR.   The method for manufacturing a pneumatic tire according to claim 1 or 2, wherein the raw carcass ply has a maximum thickness of 0.5 to 1.5 mm.   The method for producing a pneumatic tire according to any one of claims 1 to 3, wherein the Mooney viscosity of the second topping rubber is 110 to 200% of the Mooney viscosity of the first topping rubber.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein a minimum thickness of the second topping rubber to the carcass cord is 0.1 to 0.5 mm.

Images