JP2008162018A - Manufacturing method of pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a pneumatic tire enabling efficient production by restricting the kinds of rubber compounds to the utmost in a case that a plurality of kinds of tires, which have treads constituted of a plurality of rubber compounds different in hardness and are different in rubber hardness, are manufactured. <P>SOLUTION: A plurality of unvulcanized tires, which have treads 1 constituted of a combination of a plurality of rubber compounds 8a and 8b mutually different in vulcanization curve and are made the same in the combination, are molded and the rubber compound longest in the vulcanization time until becoming a practical valcanization degree among these rubber compounds is set to a standard. In a case that this standard is a matching cure type rubber compound, a plurality of vulcanization time periods are set between tc(80)-tc(max) and, in the case of a reversion cure type rubber compound and a circulation cure type rubber compound, a plurality of vulcanization time periods of tc(max) or above are set and the unvulcanized tires are respectively vulcanized in these vulcanization time periods. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a pneumatic tire, and more specifically, a pneumatic tire in which a tread is configured by combining a plurality of rubber compounds having different hardnesses is manufactured in a plurality of types including combinations having different hardness differences between tires. The present invention relates to a method for manufacturing a pneumatic tire in which the productivity is improved.

  In general, the tread characteristics of pneumatic tires have a significant effect on tire performance, and it is possible to achieve conflicting characteristics such as the relationship between rolling resistance and frictional resistance on wet road surfaces and the relationship between steering stability and low noise. Often difficult. Conventionally, a multicolor tread pneumatic tire in which a tread is configured by combining a plurality of rubber compounds having different characteristics has been proposed for this purpose.

Patent Document 1 proposes that two types of rubber compounds having different rubber hardnesses are arranged in the center region and the shoulder regions on both sides of the tread so as to achieve both steering stability and low noise. However, if you want to produce multiple types of tires with different rubber hardness differences between tires, you can prepare multiple types of rubber compounds with different compositions. There was a problem that had to be. In addition, when preparing various types of rubber compounds in this way, management becomes more complicated as the number of types increases, and accidents such as miscombination of rubber compounds may occur, so a decrease in productivity is inevitable. There was a problem.
JP 2001-10308 A

  The object of the present invention is to limit the number of types of rubber compounds as much as possible when manufacturing a plurality of types of tires in which the tread is composed of at least two types of rubber compounds having different hardnesses and having different rubber hardness differences between the tires. An object of the present invention is to provide a method for manufacturing a pneumatic tire that enables efficient production.

  In order to achieve the above object, a pneumatic tire manufacturing method according to the present invention includes a pneumatic tire in which a tread is configured by combining a plurality of rubber compounds having different hardnesses, and a plurality of types having different hardness differences between the rubber compounds. In the manufacturing method of a pneumatic tire to be manufactured, the tread is composed of a combination of a plurality of rubber compounds having different vulcanization curves obtained from the rheometer torque defined in JIS K6300-2, and the combination is the same. These unvulcanized tires were molded, and the vulcanization time of these unvulcanized tires was determined based on the rubber compound having the longest vulcanization time until reaching the practical vulcanization degree among the plurality of rubber compounds. Tc (80) to tc (max) when the compound is marching cure rubber compound In the case of a reversion cure rubber compound and a saturation cure rubber compound, a plurality of vulcanization times are set at tc (max) or more. The vulcanized tire is vulcanized.

  According to the present invention, as an unvulcanized tire, the tread is composed of a combination of a plurality of rubber compounds having vulcanization curves different from each other, and a plurality of the same combination is molded, while a plurality of vulcanization times are used as the vulcanization time. Of rubber compounds, the rubber compound having the longest vulcanization time until the practical vulcanization degree is used as a reference, and when the reference is a marching cure rubber compound, a plurality of tc (80) to tc (max) are used. In the case of reversion cure rubber compounds and saturation cure rubber compounds, a plurality of vulcanization times are set at tc (max) or more, and the plurality of unvulcanized times are set for each vulcanization time. Since vulcanized tires are vulcanized, the hardness between rubber compounds while maintaining the same combination of rubber compounds that make up the tread Can to produce a different kind of pneumatic tire. Therefore, since it is not necessary to prepare many types of rubber compounds having different compositions for each tire having different hardness differences, the tire can be produced efficiently.

  FIG. 1 is a cross-sectional view showing an example of a pneumatic tire manufactured by the manufacturing method of the present invention.

  In FIG. 1, the pneumatic tire includes a tread 1, a sidewall portion 2, and a bead portion 3, and a carcass layer 5 is inserted inside the tread 1, and both end portions thereof are inside the tire between a pair of left and right bead cores 4, 4. It is rolled up from the outside. On the outer peripheral side of the carcass layer 5, a belt layer 6 is disposed over the entire circumference of the tire, and belt covers 7 and 7 ′ are disposed on the outer side of the belt layer 6.

  The tread 1 is composed of rubber compounds 8a and 8b having different rubber hardness on the left and right of the tire center. Preferably, it is possible to achieve both steering stability and low noise performance by making the hardness of the rubber compound located outside when the vehicle is mounted larger than that of the inside rubber compound. The difference in rubber hardness between the two compounds can be varied depending on the tire size and application, and can be developed as various types of tires.

  A combination of rubber compounds having different hardnesses may be arranged in the tire width direction as in the above embodiment, or may be stacked in the tire radial direction according to the purpose. Further, rubber compounds having three or more different hardnesses may be disposed.

  As described above, the manufacturing method of the present invention is a pneumatic tire having a tread in which rubber compounds having different hardnesses are combined. As described below, when manufacturing a plurality of types having different hardness differences between rubber compounds, A plurality of types of pneumatic tires having different hardness differences between the rubber compounds can be produced while the tread rubber compounds in the vulcanized tire are kept in the same combination.

  In the present invention, as the rubber compound constituting the tread of the unvulcanized tire, at least two types of rubber compounds having different vulcanization curves obtained from the vulcanization speed defined by the torque of the rheometer defined in JIS K6300-2 are combined. It is. As these rubber compounds, the vulcanization curve may be any of marching cure rubber compounds, reversion cure rubber compounds, and saturation cure rubber compounds, and at least two of these are selected.

In the present invention, the vulcanization curve of the rubber compound is based on JIS K6300-2 “How to obtain vulcanization characteristics using a vibration vulcanization tester”, using a rotorless vulcanization tester as a rheometer, At temperature, the obtained torque is plotted on the vertical axis and the vulcanization time is plotted on the horizontal axis. The test temperature of the rheometer is the same as the temperature at which the tire is actually vulcanized. In such a vulcanization curve, as shown in FIG. 2 (A), the one in which the torque continues to increase with the lapse of the vulcanization time and does not show a clear maximum value (maximum value) _MH is called a marching cure rubber compound. As shown in FIG. 2 (B), the one that gradually decreases after the torque reaches the maximum value _MH is referred to as a reversion cure rubber compound. As shown in FIG. 2 (C), the torque reaches the maximum value M. After reaching _H , the one that keeps its maximum value almost constant is called a saturation cure rubber compound.

Here, the vulcanization time required from the start of vulcanization to the maximum value _MH is represented by tc (max). However, in the case of marching cure rubber compounds, it is defined in JIS K6300-2 as “maximum value at a specific time in a region where the vulcanization curve continues to rise and the inclination of the vulcanization curve is stable”. Therefore, in the present invention, it is set as 60 minutes from among the specific times. That is, in the present invention, the vulcanization time tc (max) in the case of the marching cure rubber compound is 60 minutes.

Moreover, the provisions of JIS K6300-2, when the difference between the minimum value _{M L} and the maximum value _{M H} of the torque is set to _{M E (M E = M H} -M L), the torque from the start of the test, _{M L} + until a 80% _{M E} of the vulcanization time defined as tc (80).

  Whether the rubber compound is a marching cure rubber compound, a reversion cure rubber compound, or a saturation cure rubber compound is mainly determined by blending. Examples of marching cure rubber compounds include SBR / silica compound compounds, examples of saturation cure rubber compounds, such as SBR / carbon black compound compounds, and examples of reversion cure rubber compounds include natural rubber. There are compound compounds.

  As described above, when an unvulcanized tire having a tread composed of a combination of a plurality of rubber compounds having different vulcanization curves is vulcanized, the rubber hardness varies depending on the degree of vulcanization. Is composed of a combination of rubber compounds having different rubber hardness. In addition, by varying the vulcanization time, it is possible to produce a plurality of types of pneumatic tires having different hardness differences between rubber compounds.

  In the present invention, the vulcanization time of the unvulcanized tire is set on the basis of the rubber compound having the longest vulcanization time until the practical vulcanization degree among the plurality of rubber compounds constituting the tread. When the reference rubber compound is a marching cure rubber compound, a plurality of vulcanization times are set between tc (80) to tc (max), and when the reversion cure rubber compound and the saturation cure rubber compound are used. Sets a plurality of vulcanization times at tc (max) or more.

When the tread is composed of multiple rubber compounds with different vulcanization times, it is necessary that all equivalent vulcanization degrees of these multiple rubber compounds have reached the practical vulcanization degree. is there. In the present invention, as a vulcanization time to reach a practical vulcanization degree, in the case of a reversion cure rubber compound and a saturation cure rubber compound, the vulcanization time tc (from the start of vulcanization until the torque reaches the maximum value _MH ) set max), also in the case of marching cure rubber compounds, torque is set to vulcanization time tc (80) to reach _M L + 80% _{M E.}

  Therefore, according to the present invention, the vulcanization time of the unvulcanized tire is set as described above, so that the plurality of rubber compounds constituting the tread all have a practical vulcanization degree, and between the rubber compounds. Plural types of pneumatic tires having different rubber hardness differences can be manufactured.

  FIG. 3A illustrates vulcanization when the tread of the unvulcanized tire is a combination of marching cure rubber compound A and reversion cure rubber compound B.

Since the vulcanization time tc (max) until the rubber compound B reaches the practical vulcanization degree is slower than the vulcanization time tc (80) until the rubber compound A reaches the practical vulcanization degree, the vulcanization time of the rubber compound B is increased. This is a case where three vulcanization times t ₁ , t ₂ , t ₃ are set based on the vulcanization time tc (max), and vulcanization is performed at the respective vulcanization times. By this vulcanization, three types of pneumatic tires with different hardness differences between the rubber compounds are produced.

  If the vulcanization time tc (80) until the rubber compound A reaches the practical vulcanization degree is slower than the vulcanization time tc (max) until the rubber compound B reaches the practical vulcanization degree, the rubber A plurality of vulcanization times are set between the vulcanization times tc (80) to tc (max) of compound A.

  FIG. 3B illustrates vulcanization when the tread of the unvulcanized tire is a combination of marching cure rubber compound A and saturation cure rubber compound C.

Since the vulcanization time tc (max) until the rubber compound C reaches the practical vulcanization degree is slower than the vulcanization time tc (80) until the rubber compound A reaches the practical vulcanization degree, the vulcanization time of the rubber compound C is increased. This is a case where three vulcanization times t ₁ , t ₂ , t ₃ are set based on the vulcanization time tc (max), and vulcanization is performed at the respective vulcanization times. By this vulcanization, three types of pneumatic tires with different hardness differences between the rubber compounds are produced.

  If the vulcanization time tc (80) until the rubber compound A reaches the practical vulcanization degree is slower than the vulcanization time tc (max) until the rubber compound C reaches the practical vulcanization degree, the rubber A plurality of vulcanization times are set between the vulcanization times tc (80) to tc (max) of compound A.

  FIG. 4A illustrates vulcanization when the tread of an unvulcanized tire is a combination of a reversion cure rubber compound B and a saturation cure rubber compound C.

Since the vulcanization time tc (max) until the rubber compound C reaches the practical vulcanization degree is slower than the vulcanization time tc (max) until the reversion cure rubber compound B reaches the practical vulcanization degree, the rubber This is a case where three vulcanization times t ₁ , t ₂ and t ₃ are set on the basis of the vulcanization time tc (max) of Compound C, and vulcanization is performed at the respective vulcanization times. By this vulcanization, three types of pneumatic tires with different hardness differences between the rubber compounds are produced.

  FIG. 4B illustrates vulcanization when the tread of the unvulcanized tire is composed of a combination of the reversion cure rubber compound B and the saturation cure rubber compound C.

Since the vulcanization time tc (max) until the rubber compound B reaches the practical vulcanization degree is slower than the vulcanization time tc (max) until the reversion cure rubber compound C reaches the practical vulcanization degree, the rubber This is a case in which three vulcanization times t ₁ , t ₂ , t ₃ are set based on the vulcanization time tc (max) of Compound B, and vulcanization is performed at the respective vulcanization times. By this vulcanization, three types of pneumatic tires with different hardness differences between the rubber compounds are produced.

  In the present invention, the rubber compound constituting the tread includes carbon black, various resins, vulcanization or crosslinking agent, vulcanization or crosslinking accelerator, various oils, anti-aging agent, plasticizer, and other tire rubber as necessary. Various additives that can be generally blended can be blended. The blending amount of these additives can be a well-known blending amount as long as the object of the present invention is not violated.

  Hereinafter, the present invention will be described with reference to examples, but the scope of the present invention is not limited thereby.

  The pneumatic tire having the tire structure shown in FIG. 1 is subjected to vulcanization molding at a vulcanization temperature of 170 ° C., and the types of rubber compounds used for the left and right treads and the vulcanization time are varied as shown in Table 1 9 Various types of pneumatic tires (Examples 1 to 9) were produced. After standing for 24 hours, left and right tread rubber layers were cut out from each pneumatic tire, and the hardness of the rubber was measured according to JIS K6253 type A. The obtained results are expressed as an index with the hardness of the right rubber compound of Example 1 as 100, and the results are shown in Table 1.

  In Table 1, the composition of three types of rubber compounds (compositions A to C) constituting the left and right treads, the vulcanization rate pattern, and the time tc (max) and tc at 170 ° C. determined in accordance with JIS K6300-2 Table 80 shows (80).

In Table 2, the materials used for each rubber composition are as follows.
・ SBR: Nippon Zeon SBR NIPOL 1712 (styrene content 23.5%)
NR: RSS # 4 Southland Rubber Silica; ZEOSIL 165GR, Rhodia Silica, Korea Co., Ltd. CB: Carbon Black, Tokai Carbon Co., Ltd. Seast KH
・ Coupling agent; Silane coupling agent, Si69 manufactured by Degussa
・ Zinc Hana; 3 types of Zinc Oxide manufactured by Shodo Chemical Co., Ltd. ・ Stearic acid: Beads stearic acid YR manufactured by NOF Corporation
Anti-aging agent: anti-aging agent, SANTOFLEX 6PPD manufactured by Flexis
・ Oil: Extract No. 4 S manufactured by Showa Shell Sekiyu KK
・ Sulfur; Fine powder sulfur and vulcanization accelerator 1 with Jinhua seal oil manufactured by Tsurumi Chemical Co., Ltd .; Noxeller CZ-G manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator 2: PERKACIT DPG GRS manufactured by Flexis

In the manufacturing method of the pneumatic tire of the present invention, it is a sectional view of the tire meridian direction showing an example of a pneumatic tire. (A)-(C) are explanatory drawings which show typically the analysis method of the vulcanization curve in the manufacturing method of the pneumatic tire of the present invention. (A) (B) is explanatory drawing which shows typically the vulcanization curve of the combination of a rubber compound in the manufacturing method of the pneumatic tire of this invention. (A) (B) is explanatory drawing which shows typically the vulcanization curve of the other combination of a rubber compound in the manufacturing method of the pneumatic tire of this invention.

Explanation of symbols

1 tread 8a, 8b rubber compound

Claims (5)

In a pneumatic tire manufacturing method for manufacturing a pneumatic tire configured by combining a plurality of rubber compounds with different hardnesses in a tread, the hardness difference between the rubber compounds is different from each other.
The tread is composed of a combination of a plurality of rubber compounds having different vulcanization curves obtained from the rheometer torque defined in JIS K6300-2, and a plurality of unvulcanized tires having the same combination are molded. The vulcanization time of the unvulcanized tire is based on the rubber compound having the longest vulcanization time until the practical vulcanization degree among the plurality of rubber compounds, and when the reference rubber compound is a marching cure rubber compound, A plurality of vulcanization times are set between tc (80) and tc (max), and in the case of reversion cure rubber compounds and saturation cure rubber compounds, a plurality of vulcanization times are set at tc (max) or more. A method for producing a pneumatic tire in which the unvulcanized tire is vulcanized in each of these vulcanization times.   The method for manufacturing a pneumatic tire according to claim 1, wherein the combination of the plurality of rubber compounds is a marching cure rubber compound and a reversion cure rubber compound.   The method for manufacturing a pneumatic tire according to claim 1, wherein the combination of the plurality of rubber compounds is a saturation cure rubber compound and a marching cure rubber compound or a reversion cure rubber compound.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 3, wherein a combination of a plurality of rubber compounds having different hardnesses is arranged in the tire width direction.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 3, wherein a combination of a plurality of rubber compounds having different hardnesses is arranged in a tire radial direction.

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