JP4572657B2 - 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 polyketone fiber as a reinforcing cord.

  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 utilized, and in particular, sufficient performance has not been achieved in terms of improving the load durability and high-speed durability of the tire. is the current situation.
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 manufacturing method of the pneumatic radial tire of the present invention that achieves the above-described object is as follows. 1. The tension ratio Th / Tn between the tension Th during the heat setting and the tension Tn during the normalizing is set to 1 to 2, and the cord size after the heat tension treatment is set to be 2. Elongating 5 to 5.0% longer, forming an unvulcanized tire using the polyketone fiber cord after the heat tension treatment as a tire reinforcing part, and vulcanizing the unvulcanized tire It is.

In the present invention, the polyketone fiber cord, in particular be 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, in the heating tension treatment after applying the RFL solution to the polyketone fiber cord, the cord dimensions before and after the heating tension treatment are set by setting the tension ratio Th / Tn at the time of heat setting and normalizing to 1-2. Since the elongation is 2.5 to 5.0%, the heat-shrinkage stress at the time of vulcanizing the unvulcanized tire allows the polyketone fiber cord to be in a tension state without relaxing the vulcanized tire. Therefore, the high strength and high modulus properties of polyketone fibers are reflected in the tires to improve the rigidity of pneumatic radial tires, improve load durability and high speed durability, and further improve steering stability. Can do.

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 twisted cord for a tire reinforcing portion, an RFL liquid (resorcin-formalin-latex liquid) as an adhesive is applied in advance in order to improve the adhesion to rubber. 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 conventional heat tension treatment step after application of the general RFL liquid, the dimensions of the twisted cord are adjusted to be kept constant before and after the treatment. However, the heating tension treatment step performed in the present invention is preferably more than 1 by adjusting the tension ratio Th / Tn between the tension Th in the heat set zone and the tension Tn in the normalizing zone to 1-2. By adjusting to 2 or less, the cord dimension after the heat tension treatment is elongated 2.5 to 5.0% longer than the dimension before the treatment. If the tension ratio Th / Tn is smaller than 1, it is difficult to extend the RFL treated cord to 2.5% or more, and if it is larger than 2, the elongation amount is larger than 5.0%. Later tires will be distorted.

  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.

The RFL-treated cord obtained by extending the length as described above is used for a carcass layer and / or a belt reinforcing layer as a tire reinforcing portion to form an unvulcanized tire, and then the unvulcanized tire is made of gold. Set to mold and vulcanize to make product tire. The tire reinforcing portion that applies the RFL treatment code, a carcass layer and / or the belt reinforcing layer.

  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 cord (carcass cord) of the carcass layer 4 is disposed 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. The two belt layers 6 are each made of a steel cord and intersect 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.

For such a pneumatic radial tire, when the unvulcanized tire is molded, the polyketone fiber cord after the RFL treatment described above is used for the carcass layer 4 and / or the belt reinforcing layer 7 as the tire reinforcing portion , and the unvulcanized tire is used. Sulfur tires are formed. As described above, the polyketone fiber cord after the RFL treatment is 2.5 to 5.0% longer than the cord size after the heat-tension treatment when the unvulcanized tire is vulcanized. A large heat shrinkage stress is generated by heating, and the tire is in a tension state after vulcanization. Since the polyketone fiber cord has high strength and high elastic modulus characteristics, the tension of the pneumatic radial tire becomes high by maintaining the tension in this way. Therefore, load durability and high speed durability are achieved. Can be improved. In addition, steering stability can be improved.

Examples 1-5, Comparative Examples 1-3
The tire size is 205 / 65R15 94H Y390L, and the number of carcass layers, the type of carcass cord, the amount of cord elongation after heat tension treatment, and the tension ratio between heat setting and normalizing are as shown in Table 1. Eight different types of pneumatic radial tires (Examples 1 to 5 and Comparative Examples 1 to 3) were produced.

  With respect to these eight 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.

なお、タイヤを解体した結果によると、比較例１のタイヤではコード切れが発生しており、また比較例２のタイヤではコードが蛇行していた。

According to the result of dismantling the tire, cord breakage occurred in the tire of Comparative Example 1, and the cord meandered in the tire of Comparative Example 2.

Examples 6 and 7, Comparative Examples 4 and 5
The tire size is set to 205 / 65R15 94H Y390L, and the types of reinforcement cords of the belt reinforcement layer, the amount of cord extension after heat tension treatment, and the tension ratio between heat setting and normalizing are changed as shown in Table 2. Four types of pneumatic radial tires (Examples 6 and 7, Comparative Examples 4 and 5) were produced.

  For these four 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 5 as 100. The larger the index value, the better.

[High-speed durability]
A test drum having a drum diameter of 1707 mm was used, and after the completion of the JIS high-speed durability test as defined in JIS D-4230, the distance traveled until the tire was broken by accelerating by 10 km / hr every 30 minutes was measured.

なお、タイヤを解体した結果によると、比較例４のタイヤでは破壊部にコードが露出していた。

According to the result of dismantling the tire, the cord of the tire of Comparative Example 4 was exposed at the fracture portion.

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)

After applying RFL liquid to a polyketone fiber cord having a single yarn fineness of 0.5 to 7 dtex, when performing heat-setting and normalizing heating tension, the tension Th during the heat setting and the tension Tn during the normalizing The tension ratio Th / Tn is set to 1 to 2, the cord dimension after the heat tension treatment is elongated 2.5 to 5.0% longer than the cord dimension before the heat tension treatment, and the polyketone after the heat tension treatment A method for manufacturing a pneumatic radial tire, in which an unvulcanized tire having a carcass layer formed using a fiber cord is molded, and the unvulcanized tire is vulcanized. After applying RFL liquid to a polyketone fiber cord having a single yarn fineness of 0.5 to 7 dtex, when performing heat-setting and normalizing heating tension, the tension Th during the heat setting and the tension Tn during the normalizing The tension ratio Th / Tn is set to 1 to 2, the cord dimension after the heat tension treatment is elongated 2.5 to 5.0% longer than the cord dimension before the heat tension treatment, and the polyketone after the heat tension treatment Using a fiber cord, an unvulcanized tire having a belt reinforcing layer formed by winding the polyketone fiber cord around the circumference of at least both ends of the belt layer in the tire circumferential direction is formed, and the unvulcanized tire is added. A method for manufacturing a pneumatic radial tire to be vulcanized. After applying RFL liquid to a polyketone fiber cord having a single yarn fineness of 0.5 to 7 dtex, when performing heat set and normalizing heat tension treatment, the tension Th during the heat setting and the tension Tn during the normalizing The tension ratio Th / Tn is set to 1 to 2, the cord dimension after the heat tension treatment is elongated 2.5 to 5.0% longer than the cord dimension before the heat tension treatment, and the polyketone after the heat tension treatment An unvulcanized tire is formed by using a fiber cord as a carcass layer and a belt reinforcing layer formed by winding the polyketone fiber cord around at least both ends of the belt layer in the tire circumferential direction. The method for producing a pneumatic radial tire according to claim 1, wherein the tire is vulcanized .

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