JP4569259B2 - Manufacturing method of pneumatic radial tire - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic radial tire, and more particularly to a method for manufacturing a pneumatic radial tire using a polyketone fiber cord as a tire reinforcing portion.

  Polyketone fiber is expected to be used for various industrial materials because it has higher strength and higher modulus than nylon fiber and polyester fiber, as well as high heat resistance and dimensional stability. Yes. Many attempts have been made to use this polyketone fiber for tire cords by paying attention to such characteristics (Patent Document 1, Patent Document 2, etc.).

However, in the conventional proposals, none of the excellent properties of the polyketone fiber are fully utilized, and particularly in terms of improving the load durability and high-speed durability of the tire. The current situation is not reached.
JP 2002-309442 A JP 2002-307908 A

  An object of the present invention is to provide a method for manufacturing a pneumatic radial tire that solves the above-described conventional problems and improves load durability and high-speed durability by utilizing the characteristics of polyketone fibers.

  The method for producing a pneumatic radial tire according to the present invention that achieves the above object includes a polyketone fiber cord having a heat shrinkage stress at 105 ° C. of 0.150 cN / dtex or less and a heat shrinkage stress at 150 ° C. of 0.449 cN / dtex or more. An unvulcanized tire using a tire reinforcing portion is molded, and the unvulcanized tire is molded by vulcanization.

In the present invention, the polyketone fiber cord, in particular are used for the carcass layer and / or the belt reinforcing layer. Among the tire reinforcing portion, thereby to further improve the load durability and high-speed durability of a pneumatic radial tire Can do.

  As described above, an unvulcanized tire using a polyketone fiber cord having a heat shrinkage stress at 105 ° C. of 0.150 cN / dtex or less and a heat shrinkage stress at 150 ° C. of 0.449 cN / dtex or more for the tire reinforcing portion. Therefore, a large heat shrinkage stress is generated during vulcanization molding, and the polyketone fiber cord is brought into a tensioned state without relaxing in the vulcanized tire. Therefore, the high strength and high modulus properties of polyketone fibers are fully reflected in the tire, improving the rigidity of pneumatic radial tires, improving load durability and high-speed durability, and further improving steering stability. Can be made.

In the present invention, the polyketone fiber refers to a fiber composed of a polymer defined by the following formula.
_{- (CH 2 -CH 2 -CO)} n - (R-CO-) m - ··· (1)
1.05 ≧ (n + m) /n≧1.00 (2)

  Fiber formation of the polyketone polymer is difficult in the melt spinning method because the characteristics of the polyketone are lost, and the wet spinning method is preferably employed. According to the wet spinning method, a desired polyketone fiber having high strength and high elasticity can be obtained. For example, the tensile strength is 7 cN / dtex or more, preferably 10 cN / dtex or more, and further 15 cN / dtex or more. Further, the tensile elastic modulus can be 100 cN / dtex or more, preferably 150 cN / dtex or more, and more preferably 250 cN / dtex or more.

  In this invention, when the said polyketone fiber is used for a tire reinforcement part, it is made into the form of the twisted cord which twisted together several filaments. The twisted cord is formed by combining a plurality of filaments having a required strength and elastic modulus by spinning and drawing to give a lower twist, and further combining the plurality of filaments to give an upper twist.

  The thickness of the single yarn filament constituting the twisted cord, that is, the single yarn fineness, is preferably 0.5 to 7 dtex, more preferably 1 to 4.5 dtex. The total fineness is preferably 500 to 4000 dtex. When the single yarn fineness is less than 0.5 dtex, fuzz frequently occurs in the spinning process, the twisting process, the weaving process, and the like, resulting in a decrease in cord strength. On the other hand, if it is thicker than 7 dtex, the polyketone fiber can be obtained by wet spinning, so that it becomes a skin core structure and is liable to cause fibrillation, which also causes a decrease in cord strength.

In order to use the above-mentioned twisted cord for a tire reinforcing part which is a carcass layer and / or a belt reinforcing layer , an RFL liquid (resorcin-formalin-latex liquid) is applied as an adhesive in order to improve adhesion to rubber in advance. Is done. The composition of the RFL solution is not particularly limited. For example, resorcin can be 0.1 to 10% by weight, formalin can be 0.1 to 10% by weight, and latex can be 1 to 28% by weight.

  In the RFL liquid treatment method for a twisted cord, an RFL liquid is applied to the twisted cord, and then a heat tension treatment is performed for drying and fixing the RFL liquid to obtain an RFL treated cord. The heating tension treatment step is composed of heat setting and normalizing, each generally having a configuration in which a conveying roller is provided in a heating oven, and any known equipment can be used. The twisted cord after the application of the RFL liquid passes through the heat set zone and the normalizing zone, whereby dry fixing (fixing) of the RFL liquid to the twisted cord and imparting physical properties are performed.

  In the present invention, the polyketone fiber cord used for the tire reinforcing portion may have a heat shrinkage stress at 105 ° C. of 0.150 cN / dtex or less and a heat shrinkage stress at 150 ° C. of 0.449 cN / dtex or more. is necessary. When the heat shrinkage stress at 105 ° C. is larger than 0.150 cN / dtex, heat shrinkage stress is generated at the initial stage of the vulcanization process for forming into a predetermined shape, making it difficult to ensure uniformity of the tire shape. Conversely, when the heat shrinkage stress at 150 ° C. is less than 0.449 cN / dtex, the heat shrinkage force when vulcanizing an unvulcanized tire is insufficient, and the polyketone fiber cord is loosened in the vulcanized tire. It is difficult to improve the tire rigidity in a tension state.

  The heat shrinkage stress in the polyketone fiber cord as described above is such that the tension per cord in the heat set zone is 0.20 cN / dtex or more and 1.50 cN / dtex or less in the heating tension treatment step described above. The ratio Th / Tn between the tension Th in the set zone and the tension Tn in the normalizing zone is in the range of 1-2, and the dimensional change before and after the treatment is -1.5 to the length before the treatment. It can be obtained by heating and tensioning to 4.0%.

  In the present invention, the heating temperature in the heat setting and normalizing is not particularly limited. For example, it can be 120 to 250 ° C. in heat setting and 120 to 270 ° C. in normalizing.

As described above, the RFL-treated cord specified by the heat shrinkage stress at 105 ° C. and 150 ° C. is used for a tire reinforcing portion which is a carcass layer and / or a belt reinforcing layer to form an unvulcanized tire, and then By setting a vulcanized tire in a mold and vulcanizing it, a product tire excellent in load durability and high-speed durability can be obtained.

  FIG. 1 is a half sectional view showing an example of a pneumatic radial tire manufactured in the present invention.

  Reference numeral 1 denotes a tread portion, 2 denotes a sidewall portion, 3 denotes a bead portion, and 4 denotes a carcass layer. Both ends of the carcass layer 4 are folded around the bead core 5 from the inside to the outside of the tire. The carcass layer 4 may be a single layer or a plurality of layers. The reinforcing cords (carcass cords) constituting the carcass layer 4 are arranged at an angle of 90 ° ± 10 ° with respect to the tire circumferential direction.

  Two belt layers 6 are arranged on the outer periphery of the carcass layer 4 so as to make one round of the tire, and each of the two belt layers 6 is made of a steel cord and intersects with each other. Further, belt reinforcing layers 7 formed by spirally winding reinforcing cords in the tire circumferential direction are arranged on both ends of the belt layer 6.

  In such a pneumatic radial tire, in the step of forming an unvulcanized tire, the polyketone fiber cord having the above-described heat shrinkage stress characteristic is used for forming the carcass layer 4 and / or the belt reinforcing layer 7. When the unvulcanized tire formed in this way is vulcanized, the polyketone fiber cord generates a large heat shrinkage stress due to heat during vulcanization, and is in a tension state in the vulcanized tire. Since the polyketone fiber cord has the characteristics of high strength and high elastic modulus, maintaining the tension state in this way keeps the pneumatic radial tire highly rigid, so that the load durability and high speed are high. Durability can be improved. In addition, steering stability can be improved.

Hereinafter, based on an Example, this invention is demonstrated concretely.
In each of the following examples and comparative examples, the heat shrinkage stress in the polyketone fiber cord is the same liquid in the RFL liquid treatment of the twisted cord of the polyketone fiber cord as in the conditions described in paragraphs 0015 to 0016. In the heating and tension treatment process of drying and fixing, the tension per cord in the heat set zone is 0.20 cN / dtex or more and 1.50 cN / dtex or less, and the tension Th in the heat set zone and the normalizing zone The ratio Th / Tn to the tension Tn at 1 to 2 is in the range of 1 to 2, and the dimensional change before and after the treatment is −1.5 to 4.0% with respect to the length before the treatment. Polyketone fiber cords having respective heat shrinkage stresses were obtained by applying heat tension treatment under various conditions within the range of conditions. The heating temperature in heat setting and normalizing was 120 to 250 ° C. in heat setting and 120 to 270 ° C. in normalizing.
Examples 1-4, Comparative Examples 1-2
The tire size is 205 / 65R15 94H Y390L, the tire structure is the same as in FIG. 1 , the carcass cord is polyester fiber, 1670 dtex / 2, and the reinforcing cords constituting the belt reinforcing layer are made different as shown in Table 1. Further, six types of pneumatic radial tires (Examples 1 to 4 and Comparative Examples 1 and 2) were manufactured.

  For these six types of pneumatic radial tires, the high speed durability was measured by the following measurement method, and the measured values were displayed as an index with Comparative Example 1 as 100. The larger the index value, the better.

[High-speed durability]
Using a test drum having a drum diameter of 1707 mm, after the completion of the JIS high-speed durability test according to JIS D-4230, the distance traveled by acceleration at 10 km / hr every 30 minutes until the tire broke was measured.

実施例５〜７、比較例３
タイヤサイズが２０５／６５Ｒ１５ ９４Ｈ Ｙ３９０Ｌ、タイヤ構造が図１で、ベルト補強層の補強コードが６６ナイロン９４０ｄｔｅｘ／２である点を共通にし、カーカス層を構成する補強コードを表１に記載のように異ならせた４種類の空気入りラジアルタイヤ（実施例５〜７、比較例３）を製作した。

Examples 5-7, Comparative Example 3
The tire size is 205 / 65R15 94H Y390L, the tire structure is the same as in FIG. 1, and the reinforcement cord of the belt reinforcement layer is 66 nylon 940 dtex / 2, and the reinforcement cords constituting the carcass layer are as shown in Table 1. Four different types of pneumatic radial tires (Examples 5 to 7, Comparative Example 3) were produced.

  With respect to these four types of pneumatic radial tires, load durability and steering stability were measured by the following measurement methods, and the measured values were displayed as an index with Comparative Example 3 as 100. The larger the index value, the better.

[Load durability]
The test tire was assembled on a rim of 15 × 6 JJ at an air pressure of 180 kPa, a constant speed of 81 km / hr on a drum with a diameter of 1707 mm, 4 hr at 85% of the maximum load corresponding to the pneumatic conditions specified by JATMA, and then the maximum The vehicle travels 6 hours at 90% of the load and 24 hours at the maximum load. If there is no failure so far, 115% of the maximum load is 4 hours, then 130% of the maximum load is 2 hours, 145% of the maximum load is 4 hours, and further, the travel distance until failure is measured at 160% of the maximum load is measured.

[Maneuvering stability]
The test tire is assembled on a rim of 15 x 6 JJ with an air pressure of 230 kPa, mounted on a passenger car with a displacement of 2.5 liters, and the feelings when five trained test drivers run on the test course are scored. Expressed by the average of 5 people.

実施例８〜９、比較例４〜５
タイヤサイズが２０５／６５Ｒ１５ ９４Ｈ Ｙ３９０Ｌ、タイヤ構造が図１で、ベルト補強層の補強コードが６６ナイロン９４０ｄｔｅｘ／２である点を共通にし、カーカス層を構成する補強コードを表１に記載のように異ならせた４種類の空気入りラジアルタイヤ（実施例８〜９、比較例４〜５）を製作した。

Examples 8-9, Comparative Examples 4-5
The tire size is 205 / 65R15 94H Y390L, the tire structure is the same as in FIG. 1, and the reinforcement cord of the belt reinforcement layer is 66 nylon 940 dtex / 2, and the reinforcement cords constituting the carcass layer are as shown in Table 1. Four different types of pneumatic radial tires (Examples 8 to 9, Comparative Examples 4 to 5) were produced.

  With respect to these four types of pneumatic radial tires, load durability and steering stability were measured by the same measurement method as described above, and the measurement values were displayed as an index with Comparative Example 5 being 100. The larger the index value, the better.

なお、タイヤを解体した結果では、比較例４のタイヤではコードが蛇行していた。

As a result of dismantling the tire, the cord of the tire of Comparative Example 4 meandered.

1 is a half sectional view showing an example of a pneumatic radial tire of the present invention.

Explanation of symbols

1 Tread 4 Carcass Layer 6 Belt Layer 7 Belt Reinforcement Layer

Claims (3)

An unvulcanized tire using a polyketone fiber cord having a heat shrinkage stress at 105 ° C. of 0.150 cN / dtex or less and a heat shrinkage stress at 150 ° C. of 0.449 cN / dtex or more as a carcass layer is molded, A method for producing a pneumatic radial tire by vulcanizing and molding a tire. Formed by winding a polyketone fiber cord having a heat shrinkage stress at 105 ° C. of 0.150 cN / dtex or less and a heat shrinkage stress at 150 ° C. of 0.449 cN / dtex or more around at least both ends of the belt layer in the tire circumferential direction. A method for producing a pneumatic radial tire, comprising molding an unvulcanized tire used for the belt reinforcing layer and vulcanizing the unvulcanized tire. The unvulcanized tire has a polyketone fiber cord having a heat shrinkage stress at 105 ° C. of 0.150 cN / dtex or less and a heat shrinkage stress at 150 ° C. of 0.449 cN / dtex or more of at least one of a carcass layer and a belt layer. 2. The method for producing a pneumatic radial tire according to claim 1 , wherein the pneumatic tire is an unvulcanized tire used for both belt reinforcing layers formed by winding the outer circumference of both ends in the tire circumferential direction.

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