JP2014189128A - Tire cord reed screen cloth and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire cord reed screen cloth capable of improving rolling workability in a tire manufacturing process and improving uniformity of a tire, and to provide a pneumatic tire using the same.SOLUTION: Provided is a tire cord reed screen cloth 1 having a body part 2 and ear parts 3 disposed on both sides of the body part 2. Plural rayon cords 2a are arranged in the body part 2, and cords 3a are arranged in the respective ear parts 3, the cords 3a including at least three pieces of lyocell fiber. The tire cord reed screen cloth 1 is used for a carcass layer of a pneumatic tire.

Description

  The present invention relates to a tire cord woven fabric mainly composed of rayon cords and a pneumatic tire using the same, and more specifically, it is possible to improve rolling processability in a tire manufacturing process and to improve tire uniformity. The present invention relates to a woven tire cord and a pneumatic tire using the same.

  As a carcass material for a pneumatic tire, a kite fabric including a plurality of aligned rayon cords is used. A woven fabric made of rayon cord has a feature of high rigidity, and is therefore preferably used particularly in high-performance tires.

  However, woven fabrics made of rayon cords are disadvantageous in that they are easily affected by ambient temperature and humidity, and cord arrangement is disturbed due to shrinkage. In particular, the disorder of the cord arrangement in the cocoon fabric is caused by the shrinkage of the ears exposed to the outside in the opposite direction of the woven fabric wound in a roll shape, and such a phenomenon is generally called an ear hanging phenomenon. And if disorder | damage | failure arises in the code | cord | chord arrangement | sequence of a cocoon fabric, there exists a problem that the rolling workability at the time of coat | covering rubber | gum with a cocoon fabric will deteriorate, and the uniformity of the tire obtained will deteriorate. Of course, if the code arrangement of the woven fabric is greatly disturbed, it is also necessary to discard the woven fabric as a defective product.

  By the way, as a technique for improving the flatness of the cocoon fabric, the total fineness of the cord constituting the ear portion of the woven fabric is made substantially the same as the total fineness of the cord of the main body portion, and the lower thread of the cord of the ear portion is used as the main body portion. The cord has a fineness smaller than the lower thread of the cord and increases the number, and the cord of the ear portion has a twist in the same direction as the cord of the main portion and the cord of the main portion has a twist in the opposite direction Have been proposed (see, for example, Patent Document 1).

  However, even if such a configuration is applied to a woven fabric made of rayon cords that are easily affected by ambient temperature and humidity, it is not possible to prevent disturbance of the cord arrangement due to contraction of the cords at the ears.

JP 2006-63486 A

  An object of the present invention is to provide a tire cord-woven fabric and a pneumatic tire using the same, which can improve the rolling processability in the tire manufacturing process and improve the uniformity of the tire.

  In order to achieve the above object, a tire cord woven fabric of the present invention is a tire cord woven fabric having a main body portion and ear portions located on both sides of the main body portion, and a plurality of rayon cords are arranged on the main body portion. On the other hand, a cord including at least three lyocell fibers is arranged in each ear.

  On the other hand, the pneumatic tire according to the present invention is characterized in that the above tire cord fabric is used for a carcass layer.

  In the present invention, a rayon cord is arranged in the main body portion, while a cord containing lyocell fiber is arranged in each ear portion. The lyocell fiber has a feature that the dimensional change due to moisture absorption is small compared to the rayon fiber. Therefore, by arranging a cord containing at least three lyocell fibers in each ear portion, the cord arrangement is prevented from being disturbed due to the shrinkage of the ear portion, and the rolling workability of the tire cord-woven fabric in the tire manufacturing process is improved. Furthermore, the uniformity of the pneumatic tire using the tire cord-woven fabric can be improved.

In the present invention, the ratio D ₁ / D ₀ between the total fineness D _{1 of the} cords containing lyocell fibers arranged in the ear portion and the total fineness D ₀ of the rayon cords arranged in the main body portion is 0.6 to 0.8. It is preferable that it exists in the range. After tire cord cord fabric is cut are rubberized to a predetermined length, but are spliced by overlapping ear portions, a total fineness D ₁ of the code containing lyocell fibers arranged in the ear unit main body portion By making it smaller than the total fineness D _{0 of the} rayon cords arranged in the above, it is possible to avoid excessive increase in rigidity and thickness of the splice part, and to improve the uniformity of the pneumatic tire.

Moreover, it is preferable that the twist coefficient K represented by the following formula (1) of the cord including the lyocell fiber arranged in the ear portion is in the range of 2900 to 3300.
K = T√D (1)
However, T: Number of twists of the cord (times / 10cm)
D: Total fineness of cord (dtex)

  In this way, by increasing the twist coefficient K of the cord including the lyocell fiber arranged in the ear portion and lowering the elastic modulus, it is possible to prevent the rigidity of the splice portion from becoming excessively large, and to improve the uniformity of the pneumatic tire. Can be improved. In particular, the twist coefficient K of the cord including the lyocell fiber arranged in the ear portion is preferably larger than the twist coefficient K of the rayon cord arranged in the main body portion.

It is a top view which shows the tire cord woven fabric which consists of embodiment of this invention. It is sectional drawing which shows the state which spliced the tire code | cord textile of FIG. It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a tire cord-woven fabric according to an embodiment of the present invention.

  As shown in FIG. 1, the tire cord woven fabric 1 is composed of a main body portion 2 located at the center in the fabric width direction and ear portions 3 located on both sides of the main body portion 2. A plurality of rayon cords 2a extending in the longitudinal direction of the fabric are arranged in the main body 2, and a cord 3a including at least three lyocell fibers extending in the longitudinal direction of the fabric is arranged in each ear portion 3. The rayon cord 2a of the main body portion 2 and the cord 3a including the lyocell fiber of the ear portion 3 constitute a kite fabric together with the weft yarn extending in the fabric width direction.

  In this way, when the rayon cord 2a is arranged in the main body portion 2 and the cord 3a including at least three lyocell fibers is arranged in each ear portion 3, the ear portion in the tire cord woven fabric 1 wound in a roll shape Even if the cable 3 is exposed for a long period of time, the cord 3a including the lyocell fiber of the ear part 3 contracts due to the influence of the ambient temperature and humidity even in a hot and humid environment such as summer. This makes it difficult to prevent the code arrangement from being disturbed by the contraction of the ear 3. As a result, the rolling processability of the tire cord / woven fabric 1 in the tire manufacturing process can be improved, and further, the uniformity of a pneumatic tire using the tire cord / woven fabric 1 can be improved.

  Here, it is necessary to arrange the cords 3a including at least 3, preferably 3 to 10, lyocell fibers in each ear portion 3. If the number of cords 3a including lyocell fibers in each ear 3 is less than 3, the effect of improving the rolling processability and uniformity becomes insufficient. In addition, even if the number of cords 3a including lyocell fibers in each ear portion 3 exceeds 10, the improvement effect beyond that cannot be expected, and only the number of cords 3a including expensive lyocell fibers increases. is there.

  The cord 3a including the lyocell fiber may be a cord of a lyocell fiber alone or a composite cord of rayon fiber and lyocell fiber. By including at least lyocell fiber, rolling processability and uniformity can be improved as compared with the cord of rayon fiber alone.

In the tire cord-woven fabric 1, the ratio D ₁ / D ₀ between the total fineness D _{1 of the} cord 3 a including lyocell fibers arranged in the ear portion 3 and the total fineness D ₀ of the rayon cord 2 a arranged in the main body portion 2. Is preferably in the range of 0.6 to 0.8. As shown in FIG. 2, the tire cord woven fabric 1 is rubberized and cut to a predetermined length, and then spliced by overlapping the ear portions 3, 3, but the lyocell arranged in the ear portion 3. It is made smaller than the total fineness D ₀ rayon cord 2a that the total fineness D ₁ is arranged in the main body portion 2 of the code 3a (shown in hatching) comprising fibers, other partial stiffness and thickness of the splice portion It is possible to avoid becoming excessively large compared to the above, and to improve the uniformity of the pneumatic tire. In particular, if the rigidity of the splice part becomes excessively large compared to other parts, a depression is formed along the splice part in the sidewall part when the pneumatic tire is filled with internal pressure. It is possible to suppress the formation of a recess in the wall portion.

Here, if the ratio D ₁ / D ₀ is less than 0.6, the rigidity of the splice part is lower than that of the other parts, so that the effect of improving the uniformity is reduced. The improvement effect is reduced.

The total fineness D ₀ of the rayon cord 2a arranged in the main body 2 and the total fineness D ₁ of the cord 3a including lyocell fibers arranged in the ear portion 3 are not particularly limited. As the woven fabric, the total fineness D ₀ of the rayon cord 2a is preferably 3000 dtex to 4000 dtex, and the total fineness D ₁ of the cord 3a including the lyocell fiber is preferably 2440 dtex to 3680 dtex.

Further, when the twist coefficient K represented by the following formula (1) is obtained, the twist coefficient K of the rayon cord 2a arranged in the main body 2 is normally in the range of 2500 to 2850, whereas the ear 3 The twist coefficient K of the cord 3a including the lyocell fiber arranged in the range is preferably in the range of 2900 to 3300. In particular, the twist coefficient K of the cord 3 a including the lyocell fiber arranged in the ear portion 3 is preferably larger than the twist coefficient K of the rayon cord 2 a arranged in the main body portion 2.
K = T√D (1)
However, T: Number of twists of the cord (times / 10cm)
D: Total fineness of cord (dtex)

  Thus, by increasing the twist coefficient K of the cord 3a including the lyocell fiber arranged in the ear portion 3 and lowering the elastic modulus, it is possible to avoid excessive increase in the rigidity of the splice portion, and to improve the uniformity of the pneumatic tire. Mitty can be improved.

  Here, when the twist coefficient K of the cord 3a including the lyocell fiber arranged in the ear portion 3 is less than 2900, the rigidity of the cord 3a is too high, so that the improvement of uniformity is lowered. The rigidity is too low, so the improvement in uniformity is reduced.

  FIG. 1 shows a pneumatic radial tire according to an embodiment of the present invention, in which 11 is a tread portion, 12 is a sidewall portion, and 13 is a bead portion. Between the pair of left and right bead portions 13, 13, at least one carcass layer 14 including a plurality of reinforcing cords extending in the tire radial direction is mounted, and an end portion of the carcass layer 14 is located inside the tire around the bead core 15. It is folded back to the outside. A bead filler 16 made of a rubber composition having a high hardness is disposed on the outer periphery of the bead core 15, and the bead filler 16 is wrapped by the carcass layer 14.

  A plurality of belt layers 17 are embedded on the outer peripheral side of the carcass layer 14 in the tread portion 11. These belt layers 17 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. On the outer peripheral side of the belt layer 17, at least one belt cover layer 18 in which reinforcing cords are arranged at an angle of 5 ° or less with respect to the tire circumferential direction is disposed for the purpose of improving high-speed durability. . It is desirable that the belt cover layer 18 has a jointless structure in which a strip material formed by aligning at least one reinforcing cord and covering with rubber is continuously wound in the tire circumferential direction. Further, the belt cover layer 18 may be disposed so as to cover the entire width direction of the belt layer 17, or may be disposed so as to cover only the outer edge portion of the belt layer 17 in the width direction.

  As a material for the carcass layer 14 of the pneumatic tire configured as described above, the tire cord-woven fabric 1 shown in FIG. 1 is used. More specifically, the carcass layer 14 is composed of the tire cord woven fabric 1 that is spliced so that the ears overlap each other. Thereby, the uniformity of a pneumatic tire can be improved. In particular, the rayon cord 2a and the cord 3a including lyocell fiber are similar in physical properties as a reinforcing material, and this point is also advantageous in improving uniformity.

  FIG. 3 illustrates a typical internal structure of a pneumatic tire, but is not limited thereto. In particular, in FIG. 3, one carcass layer is mounted between the bead portions, but a plurality of carcass layers may be mounted. In FIG. 3, the carcass layer is wound around the bead core, but the end structure of the carcass layer is not particularly limited.

  In manufacturing pneumatic tires of tire size 215 / 60R16, pneumatic structures of conventional examples, comparative examples 1 and examples 1 to 6 in which the structure of the tire cord / woven fabric used as the material of the carcass layer is different as shown in Table 1 I made a tire.

  In the conventional example, rayon cords are arranged on the main body and ears of the tire cord / woven fabric, and in Comparative Examples 1 and Examples 1-6, the ear portions are arranged on the main body of the tire cord / woven fabric. The cords containing lyocell fibers are arranged in the same, and the number of cords containing lyocell fibers in each ear is different.

  For these conventional examples, Comparative Example 1 and Examples 1 to 6, the rolling processability of the tire cord knit fabric and the uniformity of the pneumatic tire were evaluated by the following evaluation method, and the results are also shown in Table 1. .

Rollability:
Each tire cord bag fabric was stored in a warehouse for 30 days in a rolled state, and then the rolling processability when the tire cord bag fabric was coated with rubber was evaluated. The evaluation results are indicated by “◯” when the rolling process can be performed smoothly, and “△” when the rolling speed needs to be reduced in order to ensure good passability when performing the rolling process. The case where wrinkles occurred on the rolled material even when the rolling speed was reduced was indicated by “x”.

Uniformity:
The internal pressure of each test tire was set to 230 kPa, and the depth of a minute recess formed in the sidewall portion along the splice portion of the carcass layer was measured. The evaluation results are shown as an index with the conventional example being 100. The smaller the index value, the better the uniformity.

  As is apparent from Table 1, in Comparative Example 1, the number of cords including lyocell fibers in each ear is less than 3, so that an improvement effect on rolling workability and uniformity is obtained in comparison with the conventional example. I couldn't.

  On the other hand, in Example 1, since the number of cords including lyocell fibers in each ear is 3 or more, rolling workability and uniformity improvement effects were obtained in comparison with the conventional example. However, even if the number of cords including lyocell fibers in each ear portion was more than 10 as in Example 2, no further effect was obtained. When a cord made of a single lyocell fiber is used in the ear as in Example 3, the rolling processability is further improved, but the cord rigidity increases due to the increase in lyocell fiber, so the effect of improving uniformity is It was suppressed. In Example 4, since the total fineness of the cord including the lyocell fiber arranged in the ear portion was reduced, the effect of further improving the uniformity was obtained with the reduction in the rigidity and thickness of the splice portion. In Example 5, since the twist coefficient of the cord including the lyocell fiber arranged in the ear portion was increased, a further improvement effect of uniformity was obtained with a decrease in the cord elastic modulus. However, when the twist coefficient of the cord including the lyocell fiber arranged in the ear portion as in Example 6 exceeds 3300, the rigidity of the splice portion is excessively lowered, so that the effect of improving the uniformity is suppressed.

DESCRIPTION OF SYMBOLS 1 Tire cord woven fabric 2 Main part 2a Rayon cord 3 Ear part 3a Cord containing lyocell fiber

Claims (5)

  A tire cord woven fabric having a main body portion and ear portions located on both sides of the main body portion, wherein a plurality of rayon cords are arranged in the main body portion, and each ear portion includes at least three lyocell fibers A tire cord woven fabric characterized in that The ratio D ₁ / D ₀ of the total fineness D _{1 of the} cord including the lyocell fiber arranged in the ear portion and the total fineness D ₀ of the rayon cord arranged in the main body portion is in the range of 0.6 to 0.8. The tire cord woven fabric according to claim 1, wherein The tire cord-woven fabric according to claim 1 or 2, wherein a twist coefficient K represented by the following formula (1) of the cord including the lyocell fiber arranged in the ear portion is in the range of 2900 to 3300. .
K = T√D (1)
However, T: Number of twists of the cord (times / 10cm)
D: Total fineness of cord (dtex)   4. The tire cord woven fabric according to claim 3, wherein a twist coefficient K of a cord including lyocell fibers arranged in the ear portion is larger than a twist coefficient K of a rayon cord arranged in the main body portion.   A pneumatic tire using the tire cord knit fabric according to claim 1 for a carcass layer.

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