JP4237510B2 - Pneumatic tire - Google Patents

Description

【００５６】
【表２】

【００５７】
表１において、実施例のタイヤは耐久性、高速耐久性を良好に維持し、軽量化を実現することができる。比較例１のＰＥＮの撚りコードを用いたタイヤは、耐久性能は実施例と同等であるが、コード径が従来通り大きくタイヤ軽量化が達成されない。比較例２はＰＥＮテープの厚みが大であるため、トレッド部の薄肉化が実施できず軽量化が未達であり、またテープ側部の接着破壊に起因するセパレーションがベルト部とベルト補強層間に発生して耐久性が劣り、またテープにクラックが生じ強力保持率が低下している。比較例３は、テープ幅が広くベルト層との密着性が悪く、ベルト層とベルト補強層との間にボイドが発生し耐久性の低下が著しい。また比較例４はテープが薄すぎるため素材のモジュラスが活用されずに締め付けによる補強効果が十分に得られず、高速耐久性が劣り、操縦安定性や転がり抵抗にも影響を及ぼしている。
【００５８】
また、表２に示す通り、実施例と素材が異なる同一形状のテープを用いた比較例５，６は、タイヤ径の成長が大きく高速耐久性に悪影響し、故障状態もベルト補強層に起因するものとなり、素材特性の差が顕著に表れてタイヤ性能への影響が明確であることが分かる。
【００５９】
【発明の効果】
以上説明したように、本発明の空気入りタイヤは上記構成としたので、タイヤの軽量化を実現し、かつ高速耐久性を高め、操縦安定性に優れ、さらにロードノイズや転がり抵抗を低減する空気入りタイヤを提供することができる。
【図面の簡単な説明】
【図１】 実施形態の空気入りタイヤの右半断面図である。
【図２】 トレッド部の部分拡大図である。
【図３】 ベルト補強層の構造例を示す概略断面図である。
【符号の説明】
１……空気入りタイヤ
２……トレッド部
３……サイドウォール部
４……ビード部
５……カーカス層
６……ベルト層
７……第１ベルト補強層
８……第２ベルト補強層
１０……テープ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that is lightweight, enhances high-speed durability, has excellent steering stability, and can reduce road noise and rolling resistance.
[0002]
[Prior art]
In a pneumatic radial tire for a passenger car, a tire is used in which a belt reinforcing layer in which an organic fiber cord is wound so as to be substantially parallel to the tire circumferential direction is disposed on the outer circumferential side of the belt layer in the tire radial direction. This belt reinforcing layer reinforces the so-called “tape effect” of the belt layer by tightening the outer periphery of the belt layer and improves the tension and rigidity in the belt circumferential direction, thereby improving high-speed durability and steering stability. It reduces rolling resistance, suppresses vibration transmission from the road surface, and reduces road noise (in-vehicle noise).
[0003]
In recent years, the flattening of tires has rapidly spread with the increase in the speed, output, and quality of automobiles, and as a result, the tire weight and the centrifugal force applied to the tread have increased due to the increased weight of the tread. It affects tire performance such as rolling resistance and road noise, including high-speed durability, and maintains tire performances such as high-speed durability and steering stability at a high level in addition to the conventional weight reduction requirements of tires. It is requested.
[0004]
Conventionally, nylon fiber cords such as nylon 66 have been generally used for this belt reinforcing layer in terms of adhesion to rubber, heat shrinkage properties, etc., but nylon fiber cords have a relatively low tensile modulus (modulus). For this reason, it is difficult to satisfy both the above-described weight reduction of the tire and high demand performance.
[0005]
Therefore, various studies have been made on the use of cords having a higher modulus than conventional nylon fiber cords as cords in the belt reinforcing layer. For example, a radial tire in which a belt reinforcing layer is formed by a fiber cord mainly composed of polyethylene-2,6-naphthalate fiber having a specified elongation measured under specific conditions, and the expansion rate of the belt layer is increased (Patent Document 1) A pneumatic tire in which the belt reinforcing layer is made of a polyester fiber cord and the outermost end in the tire width direction of the belt reinforcing layer is disposed between the first belt layer outer end and the second belt layer outer end. (See Patent Document 2).
[0006]
There has also been proposed a tire in which the cord embedded in the belt layer is made of a polyester monofilament cord and the cord embedded in the belt reinforcing layer is made of a polyester twisted cord (see Patent Document 3).
[0007]
[Patent Document 1]
JP 2001-163209 A
[Patent Document 2]
JP 2002-79806 JP
[Patent Document 3]
Japanese Patent Laid-Open No. 2002-96606
[Problems to be solved by the invention]
However, although the tires described in Patent Documents 1 to 3 can improve high-speed durability and uniformity, reduce road noise, improve driving stability and riding comfort, Are not satisfied at the same time.
[0011]
The present invention has been made in view of the above problems, and provides a pneumatic tire that realizes weight reduction of the tire, enhances high-speed durability, has excellent steering stability, and can reduce road noise and rolling resistance. It is intended to provide.
[0012]
[Means for Solving the Problems]
The pneumatic tire of the present invention has at least two belt layers on the outer peripheral side of the carcass layer in the tread portion, and a belt reinforcing layer composed of at least one layer on the outer side in the tire radial direction of the belt layer. A pneumatic tire disposed so as to cover at least both ends in the direction, wherein the belt reinforcing layer has a thickness of 0.05 to 0.5 mm, a width of 1 to 10 mm, and the width and thickness. A tape made of a polyethylene naphthalate film having a ratio (width / thickness) of 5 to 50 so that the tensile modulus of elasticity is in the range of 10 GPa to 200 GPa so as to be substantially parallel to the tire circumferential direction. It is formed by winding spirally, characterized by comprising.
[0013]
According to the pneumatic tire of the present invention, by forming the belt reinforcing layer with a tape made of a polyethylene naphthalate (hereinafter referred to as PEN) film , the thickness of the belt reinforcing layer is surely reduced and the tread portion is thinned. It is possible to reduce the weight of the tire.
[0014]
In addition, PEN has excellent tensile modulus (modulus), high strength, thermal stability, and other properties that are superior to polyethylene terephthalate (hereinafter referred to as PET) and nylon, and a tape made of PEN is used for the belt reinforcement layer. As a result, the tension and rigidity in the tire circumferential direction are maintained at a high level even under high heat generation during high-speed driving, and the belt layer is secured sufficiently without deteriorating the tightening effect of the belt layer. High-speed durability is improved by suppressing shear strain between layers, steering stability is excellent, rolling resistance is reduced, and vibration transmission from road surface unevenness can be suppressed, and road noise can be reduced.
[0015]
In particular, in the case of the present invention, the tape has a cross-sectional dimension of 0.05 to 0.5 mm in thickness and 1 to 10 mm in width, and the ratio of the width to the thickness (width / thickness) is 5 to 5. The tensile modulus (modulus) is in the range of 10 GPa to 200 GPa. As a result, the weight reduction and the tire performance can be easily obtained, and the tape can be easily wound in a spiral to easily form a belt reinforcing layer, thereby improving the tire productivity.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
FIG. 1 is a right half sectional view of a tire showing a pneumatic tire 1 according to an embodiment. In the figure, 2 is a tread portion, 3 is a sidewall portion, and 4 is a bead portion.
[0018]
The carcass layer 5 is mounted between a pair of left and right bead cores 41 embedded in the bead portion 4, and its end portion 51 is folded and locked from the inside to the outside so as to sandwich the bead filler 42 around the bead core 41. ing. A belt layer 6 including two belt layers 6 a and 6 b intersecting each other is disposed on the outer peripheral side of the carcass layer 5 of the tread portion 2, and further, belt reinforcing layers 7 and 8 are disposed outside the belt layer 6 in the tire radial direction. Is disposed in the circumferential direction so as to cover the belt layer 6.
[0019]
The carcass layer 5 is composed of at least one carcass ply in which fiber cords such as polyester are arranged in a direction substantially perpendicular to the tire circumferential direction.
[0020]
The belt layer 6 includes two belt layers 6a and 6b in which steel cords are arranged at an inclination angle of 15 to 35 ° with respect to the tire circumferential direction, and is disposed in a direction in which the two steel cords cross each other. ing.
[0021]
The belt reinforcement layers 7 and 8 are disposed on the outer side in the tire radial direction of the belt layer 6, and are provided on the outer side of the first belt reinforcement layer 7 and the first belt reinforcement layer 7 that covers the entire width of the belt layer 6 in the width direction. The belt belt 6 is composed of a narrow second belt reinforcing layer 8 that covers both end regions of the belt layer 6.
[0022]
The belt reinforcing layers 7 and 8 are formed of a tape 10 made of a polyethylene naphthalate film so that the tape 10 is substantially parallel to the tire circumferential direction (an angle of 0 to 5 ° with respect to the tire circumferential direction). It is formed by being wound in a spiral shape.
[0023]
As shown in FIG. 2, the belt reinforcing layers 7 and 8 are embedded in the tread rubber so that the width direction of the tape 10 is arranged in parallel with the belt layer 6.
[0024]
The PEN forming the tape 10 is composed of a polymer containing 85 mol% or more, preferably 90 mol% or more of ethylene-2,6-naphthalate. This polymer is disclosed in a known method, for example, JP-A-5-163612. It can be synthesized according to the method described.
[0025]
The tape 10 is formed by, for example, cutting a film having a predetermined thickness, which is formed by a normal film casting method obtained by extrusion molding of a PEN molten resin, or by a biaxial stretching method, into a tape-like narrow width. The method for forming the tape is not particularly limited.
[0026]
The tape 10 has a thickness of 0.05 to 0.5 mm, preferably 0.05 to 0.3 mm. If the thickness is less than 0.05 mm, it is too thin. The tape cannot be fully utilized, the reinforcing effect of the belt layer cannot be exhibited, and it is difficult to obtain a desired tire performance, and it is also difficult to produce a tape having a uniform thickness. On the other hand, if the thickness exceeds 0.5 mm, the thickness of the belt reinforcing layer cannot be reduced, so that the thickness of the tread portion cannot be reduced, and the weight of the tire cannot be reduced. Not only is it likely to cause a failure, but also an adhesive breakage with the rubber at the end of the tape is likely to occur, resulting in the initiation of a peeling failure (separation) from the rubber. Moreover, it becomes difficult to obtain an appropriate elongation of the tread portion in the mold during vulcanization molding, and product defects such as deformation of the tread portion are likely to occur.
[0027]
The tape width is 1 to 10 mm, preferably 2 to 5 mm. If the width is less than 1 mm, the handling of the tape is bad in the manufacturing process such as winding at the time of tire manufacture, and the man-hour for winding the tape in a spiral shape And the productivity of the tape itself is lowered, which is not preferable. If the tape width exceeds 10 mm, it is difficult to attach the tape along the curved surface of the belt layer, and it is difficult to apply the tape. The molding accuracy of the belt reinforcing layer is lowered, resulting in a decrease in durability, and the object of the present invention cannot be achieved.
[0028]
The tape width / thickness ratio is preferably in the range of 5-50, more preferably in the range of 5-40. In the range of 5 to 50, the material characteristics and shape characteristics of the tape are compatible, the belt layer reinforcing effect and bending fatigue resistance can be maintained well, and the above tire performance can be obtained. By making the process easy, molding accuracy can be improved and molding efficiency can be increased.
[0029]
The tensile modulus (modulus) is preferably in the range of 10 GPa to 200 GPa, more preferably 30 GPa to 100 GPa. Furthermore, it is preferable that the decrease in the modulus is small even at high temperatures. The tensile elastic modulus is a value measured at room temperature in accordance with the method defined in JIS K7127.
[0030]
When the modulus of the tape 10 is less than 10 GPa, it is difficult to sufficiently obtain the tension and rigidity in the tire circumferential direction, the high-speed durability and the steering stability cannot be satisfied, and in order to ensure the rigidity, the use amount increases and the tire weight increases. If the cost is increased and the pressure exceeds 200 GPa, the tape becomes too rigid, and separation due to a difference in modulus from rubber tends to occur.
[0031]
Further, the tape 10 is used for a normal tire cord adhesion treatment, for example, a treatment mainly composed of resorcin-formalin-rubber latex (RFL), or an epoxy-based material, in order to improve adhesion to rubber. It is preferable to perform a surface treatment using a treatment agent containing an adhesive.
[0032]
Further, it is preferable that at least one side, preferably both sides, of the tape 10 is rubber-coated, so that the adhesiveness between the tape 10 and the peripheral rubber can be improved and the tire durability can be improved. In particular, this coated rubber can be improved in a higher degree of durability by using an adhesive rubber compound that improves the adhesiveness to the tape 10 through the treatment agent such as the RFL. .
[0033]
As a method of winding the tape 10 on the outer periphery of the belt layer 6 in a spiral shape substantially parallel to the tire circumferential direction (at an angle of 0 to 5 ° with respect to the tire circumferential direction), one tape 10 is wound on the belt. Wrapped in a spiral shape with a predetermined interval in the width direction from one end side of the belt layer 6 with respect to the circumferential surface of the layer 6, and a plurality of tapes 10 are aligned in parallel and covered with rubber to form a ribbon The ribbon may be wound around the outer peripheral surface of the belt layer 6 in a spiral manner.
[0034]
The belt reinforcing layers 7 and 8 are preferably provided so as to protrude outward in the width direction of the belt layer 6 and cover the end of the belt layer 6.
[0035]
The interval between the tapes 10 in the belt reinforcing layers 7 and 8 is not particularly limited, and the end portions of the tapes 10 may be overlapped with each other, or a gap may be provided between the tapes 10 to be wound spirally. However, in order to improve the adhesiveness between the tape 10 and the peripheral rubber in the belt reinforcing layer, an appropriate space is provided between the parallel tapes 10 and a cross-linked portion between the upper and lower rubbers of the tape 10 is provided. It is preferable to keep it. In this case, the tape interval is about 10 to 100% of the tape width, and if the tape interval is narrow, the throwing effect between the rubbers at the cross-linking portion is reduced, and if it is too wide, the reinforcing effect by the tape is not sufficiently exhibited. .
[0036]
By using the PEN tape 10 for the belt reinforcement layers 7 and 8, the cord diameter (thickness) is smaller than that of the conventional nylon or PET fiber cord, thereby reliably reducing the thickness of the belt reinforcement layer and the tread portion. The thickness of the tire can be reduced to reduce the weight of the tire.
[0037]
In addition, the tape 10 has a stable high modulus characteristic at high temperatures and dimensional stability to ensure the tension and rigidity in the tire circumferential direction, and the belt layer tightening effect even under high heat generation during high-speed running, like a conventional nylon cord It can be fully utilized without lowering, and it suppresses the growth in the tire radial direction due to centrifugal force during running, and prevents the belt cord from rising up at the end of the belt layer and the occurrence of shear strain between layers, improving high-speed durability can do.
[0038]
Further, by winding the tape 10 in a spiral shape to form a belt reinforcement layer, the belt layer is tightened to achieve a high “strength” reinforcement effect, improving steering stability and rolling resistance, and tread The circumferential tension of the part increases, making it difficult to spread vibration from the road surface, reducing road noise, and improving the uniformity by reducing the joint part, equal to or better than the tire using conventional nylon cord Performance can be maintained.
[0039]
In addition to the structure shown in FIG. 1, this belt reinforcing layer is composed of one reinforcing layer 9a over the entire width of the belt layer 6 (see FIG. 3 (a)) and two layers of reinforcing in the entire width. Those provided on the layers 9b and 9c (see FIG. 3B), those provided with the two reinforcing layers 9d and 9e only on both end regions of the belt layer (see FIG. 3C), etc. May be.
[0040]
(Example)
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.
[0041]
The pneumatic tires of the examples and comparative examples are radial tires having a tire size of 225 / 50R16, the carcass is 1100 dtex / 2, the number of twisted PET cords with a twist number of 47 × 47 times / 10 cm is 55/5 cm. Two pieces were used, and the belt layer used was a steel cord having a 2 + 2 × 0.25 structure and the number of driven steel cords was 40 pieces / 5 cm, and the two pieces were arranged crossing at an angle of 25 ° with respect to the tire circumferential direction. This is a general radial tire having an internal structure and a tread pattern of a normal pneumatic radial tire.
[0042]
As shown in FIG. 1, the first belt reinforcing layer 7 is provided 5 mm wider than the belt layer 6 at both ends so as to cover the entire width of the belt layer 6, and the second belt reinforcing layer 8 is formed of the belt layer 6. A width of 30 mm is provided so as to cover only both end regions, and a width of 5 mm is widened at both ends, and the tape angle is approximately 0 ° with respect to the tire circumferential direction.
[0043]
The tapes and cords used for the belt reinforcement layer are as follows. In the case of the tapes, the surface of each tape was subjected to an adhesive treatment with an RFL adhesive, and then both sides were coated with 0.1 mm thick adhesive rubber, A single tape or cord is spirally wound around the outer periphery of the belt layer 6 at a predetermined density to form belt reinforcing layers 7 and 8, and each tire is molded, vulcanized and tested in accordance with a conventional method. A radial tire was manufactured.
[0044]
[Tape and cord structure]
Example: PEN having a thickness of 0.1 mm and a width of 3 mm, and the driving density is 7 pieces / 25 mm.
[0045]
Comparative Example 1: 1100 dtex / 2 twisted cord of PEN, the number of twists is 48 × 48 times / 10 cm. The driving density is 19/25 mm.
[0046]
Comparative Example 2: PEN having a thickness of 0.7 mm and a width of 3 mm, and the driving density is 7 pieces / 25 mm.
[0047]
Comparative Example 3: PEN having a thickness of 0.1 mm and a width of 11 mm, and the driving density is 2 pieces / 25 mm.
[0048]
Comparative Example 4: PEN thickness 0.03 mm, width 3 mm tape, driving density is 7 pieces / 25 mm.
[0049]
Comparative Example 5: PET having a thickness of 0.1 mm and a width of 3 mm, and the driving density is 7 pieces / 25 mm.
[0050]
Comparative Example 6: Nylon 66 having a thickness of 0.1 mm and a width of 3 mm, and the driving density is 7 pieces / 25 mm.
[0051]
The tires of the above Examples and Comparative Examples were evaluated for tire weight, durability performance, and high speed durability performance by the following test methods, and the results are shown in Tables 1 and 2. In Comparative Examples 5 and 6, evaluation of durability performance was omitted.
[0052]
Tire weight: The weight of each test tire was measured, and an average value of 10 measurements was obtained.
[0053]
Durability evaluation: Each tire is adjusted to the maximum air pressure of JIS standard in a room at 25 ± 2 ° C and left for 24 hours. After that, the air pressure is readjusted and the tire is loaded with twice the maximum load of JIS standard. The vehicle was run on a 1.707 m drum at a speed of 60 km / h, and the running distance until the failure occurred and the separation failure occurrence position were observed (durability 1). In addition, the tire that stopped traveling at the time of traveling at 17,000 km was disassembled, the separation occurrence state of the belt portion was observed, the tape or cord of the belt reinforcing layer was collected, and the strength retention rate was obtained (durability 2).
[0054]
High-speed durability evaluation: Performed by the step speed method according to the method prescribed in US standard FMVSS No. 109, that is, after passing a running test for a specified time at a specified speed, a product that failed without being recognized and passed 30 The drum running was continued until it broke down by increasing the speed by 8 km / h every minute. The speed (Km / h) at the time of failure occurrence and the elapsed time (minute) at that speed were measured, and the failure state was observed. Further, the maximum temperature (° C.) of the tread portion and the growth amount (mm) of the tire outer diameter at a time point of 260 Km / h were measured.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
In Table 1, the tires of the examples can maintain good durability and high-speed durability, and can realize weight reduction. The tire using the PEN twist cord of Comparative Example 1 has the same durability performance as that of the example, but the cord diameter is large as before, and the weight reduction of the tire is not achieved. In Comparative Example 2, since the thickness of the PEN tape is large, the tread portion cannot be thinned and the weight reduction has not been achieved, and the separation caused by the adhesive breakage of the tape side portion is between the belt portion and the belt reinforcing layer. Occurrence is inferior and durability is inferior, and cracks are generated in the tape and the strength retention is reduced. In Comparative Example 3, the tape width is wide and the adhesion to the belt layer is poor, and voids are generated between the belt layer and the belt reinforcing layer, resulting in a significant decrease in durability. In Comparative Example 4, since the tape is too thin, the modulus of the material is not utilized and the reinforcement effect by tightening cannot be sufficiently obtained, the high-speed durability is inferior, and steering stability and rolling resistance are also affected.
[0058]
In addition, as shown in Table 2, Comparative Examples 5 and 6 using tapes of the same shape that are different from the examples have a large tire diameter growth and adversely affect high-speed durability, and the failure state is also caused by the belt reinforcing layer. Thus, it can be seen that the difference in material characteristics is remarkably exhibited and the influence on the tire performance is clear.
[0059]
【The invention's effect】
As described above, since the pneumatic tire of the present invention has the above-described configuration, the air that realizes weight reduction of the tire, enhances high-speed durability, has excellent steering stability, and further reduces road noise and rolling resistance. An inset tire can be provided.
[Brief description of the drawings]
FIG. 1 is a right half sectional view of a pneumatic tire according to an embodiment.
FIG. 2 is a partially enlarged view of a tread portion.
FIG. 3 is a schematic cross-sectional view showing a structural example of a belt reinforcing layer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire 2 ... Tread part 3 ... Side wall part 4 ... Bead part 5 ... Carcass layer 6 ... Belt layer 7 ... 1st belt reinforcement layer 8 ... 2nd belt reinforcement layer 10 ... …tape

Claims (1)

The tread portion has at least two belt layers on the outer periphery side of the carcass layer, and at least one belt reinforcing layer made of at least one layer on the outer side in the tire radial direction of the belt layer covers at least both ends in the belt layer width direction. A pneumatic tire disposed on
The belt reinforcing layer is made of polyethylene naphthalate having a thickness of 0.05 to 0.5 mm, a width of 1 to 10 mm, and a ratio of width to thickness (width / thickness) of 5 to 50 . tape consisting of a film, the tensile pneumatic tire modulus is characterized by comprising formed by winding the spirally so as to be substantially parallel to the tape in the tire circumferential direction in the range of 10GPa~200GPa .

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