JP2006069390A - Pneumatic radial tire for high-speed heavy load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve cut resistance by increasing the strength of a protective layer cord and enhance the constructing property of a protective layer at the time of manufacturing in a pneumatic radial tire for a high-speed heavy load. <P>SOLUTION: The pneumatic radial tire for the high-speed heavy load has a belt layer disposed between a tread rubber layer of contacting part of a road surface and a carcass layer embedded in a coated rubber positioned at the inner side of the tire radial direction from the tread rubber layer and a protective layer 35 to cover the outer side belt layer in the tire radial direction from the belt layer. The protective layer 35 is constituted so that a ribbon-like member 33 having a ribbon-like shape is formed by continuously being wound to the belt layer in spiral-like, and the ribbon-like member 33 is arranged by a plurality of organic fiber belt cords extended in wave-like shape or zigzag-like shape along the tire circumferential direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic radial tire for high-speed heavy loads that is mounted on an aircraft or the like and is rotated at a high speed while being loaded with a heavy load.

  In general, as one of the required performances of a high-speed heavy-duty pneumatic radial tire mounted on an aircraft or the like, securing cut resistance against foreign matters on the road surface can be mentioned. In other words, in an aircraft tire, there is a case where a foreign object is stepped on to reach a burst or peel-off, and further, a fragment of the tire may cause damage to the airframe, so that improvement of cut resistance is an important issue.

  An important element for improving cut resistance is the design of a protective layer. Conventionally, as a technique for reinforcing the protective layer, a technique using a Kevlar cord for the protective layer is known (see, for example, Patent Documents 1 and 2). Kevlar cords have higher cut resistance because they are stronger than nylon cords used for belt plies and the like.

  Further, in the techniques disclosed in Patent Documents 1 and 2, the wave belt structure is used for the protective layer, and the protective layer is not subjected to a load due to the tension. Therefore, the cut resistance is further improved.

  However, even a protective layer using a Kevlar cord has a limit in improving cut resistance, and in recent years, further improvement in cut resistance has been demanded.

Therefore, in order to further improve the cut resistance, a method for suppressing the diameter growth rate due to the internal pressure has been introduced. As a method for suppressing such a diameter growth rate, not only nylon fibers but also Kevlar fibers are used for the belt cord, and a technique for increasing the resistance to internal pressure has been introduced. As another method of suppressing the diameter growth rate due to the internal pressure, a method of suppressing the diameter growth rate by adopting a structure in which more belt cords are arranged at the center portion than at the shoulder portion has been proposed.
JP-A-3-7601 JP-A-5-294107

  However, simply increasing the strength of the belt cord makes the belt cord hard and difficult to handle. For this reason, since the workability at the time of manufacture deteriorates, it is difficult to put a high-speed heavy-duty pneumatic radial tire having such a belt cord into practical use.

  That is, when the belt cord is hard, the belt cord is difficult to wind at a location where the diameter difference from the center portion is large, such as a shoulder portion, and workability is deteriorated.

  Further, when the belt cord becomes hard, the deformation ratio of the belt cord becomes small with respect to the deformation of the tread rubber. For this reason, the distortion around the belt cord is increased, and the belt cord and the tread rubber are easily peeled off. In particular, at the joint portion (belt cord end portion) of the protective layer, there has been a problem that separation of the belt cord and the tread rubber is increased, resulting in separation and peeling off.

  On the other hand, in the structure in which more belt cords are arranged in the center part than in the shoulder part as described above, it is necessary to reduce the crown radius in order to obtain such a structure. There was a problem that the diameter difference became large and it was difficult to wind the belt cord during production.

  Therefore, the present invention has been made in view of the above-described problems, and is capable of improving the workability of the protective layer at the time of manufacture while increasing the strength of the protective layer cord and improving the cut resistance. An object is to provide a heavy-duty pneumatic radial tire.

  In order to solve the above-described problems, the first feature of the present invention is that a tread rubber layer (tread rubber layer 26) serving as a contact portion with a road surface, and a covering rubber positioned on the inner side in the tire radial direction from the tread rubber layer are provided. A high-speed heavy load having a main belt (belt layer 29) disposed between the buried carcass layer (carcass layer 21) and a protective layer (protective layer 35) covering the main belt on the outer side in the tire radial direction from the main belt. In the heavy duty pneumatic radial tire (pneumatic radial tire 11), the protective layer is formed by winding a ribbon-like body (ribbon-like body 33) having a ribbon-like shape around the main belt in a spiral manner. The ribbon-like body is configured by arranging a plurality of organic fiber belt cords (waved belt cords 33a) extending in a wavy or zigzag shape along the tire circumferential direction. The gist that you are.

  According to this feature, the protective layer that protects the main belt is hard so as to increase the tensile breaking strength of the protective layer by forming a so-called spiral winding in which a ribbon-like body is continuously spirally wound around the main belt. Even when a belt cord having low flexibility is used as a ribbon-like body, the workability of the protective layer can be improved. As a result, even when applied to a high-speed heavy-duty pneumatic radial tire with a small crown radius, it is possible to prevent a difference in diameter between the shoulder portion and the center portion, and the belt cord in the shoulder portion. The problem that the (ribbon-like body) becomes difficult to wind can be solved.

  In addition, since the protective layer is formed by spiral winding of a ribbon-like body, the adhesiveness between the protective layer and the main belt (case) can be improved, and the joint portion formed at the end of the belt cord or the like Therefore, failures such as separation and peel-off that have occurred in this portion can be suppressed, and durability can be improved.

  A second feature of the present invention is that, in the first feature of the present invention, the main belt tensile rupture strength is 6.3 cN / dtex or more, which is the tensile rupture strength of the main belt, Elongation rate at a load of 0.3 cN / dtex is 0.2 to 2.0%, Elongation rate at a load of 2.1 cN / dtex in the extension direction is 1.5 to 7.0%, and 3 in the extension direction The gist is that the elongation at the time of 2 cN / dtex loading is 2.2 to 9.3%, and the protective layer has a tensile breaking strength equal to or higher than the main belt tensile breaking strength.

  According to such a feature, while maintaining the pressure resistance required for a pneumatic radial tire for high-speed heavy loads, growth in the tire radial direction at the time of tire internal pressure filling is suppressed, so that the cut resistance of the radial tire is reduced. Can be prevented.

  According to a third feature of the present invention, in the first feature of the present invention, the main belt has a thickness at a central portion in the tread width direction of the main belt as G0, and the main belt has a maximum width of 2 / When the thickness at the width position of 3 is G2, the gist is that these relationships are 0.35 ≦ G2 / G0 ≦ 0.85.

  According to such a feature, by setting G2 / G0 to be 0.35 or more, it is possible to prevent the belt cord or the like located in the vicinity of the shoulder portion from being burdened by excessive tension, and to prevent the pressure resistance performance from being lowered. be able to. Further, by setting G2 / G0 to 0.85 or less, it becomes possible to effectively utilize the belt layer disposed at the width position of 2/3 of the maximum width of the main belt from the central portion of the main belt. . In other words, when G2 / G0 exceeds 0.85, the belt layer disposed at the position is not effectively utilized, and the weight of the pneumatic radial tire for high-speed heavy load increases as the belt layer at other positions is strengthened. However, this increase in weight can be suppressed.

  A fourth feature of the present invention is the separation member according to the first feature of the present invention, wherein the protective layer and the main belt are separated from each other with a predetermined distance between the protective layer and the main belt. The gist of the invention is that the protective layer is formed by winding a belt cord coated with a resin extruded at a high temperature around the separation member.

  According to this feature, since the protective layer can be molded at a high temperature, the workability in forming the protective layer can be further enhanced.

  A fifth feature of the present invention is that, in the first feature of the present invention, the organic fiber is formed by spinning a polymer dope obtained by polymerizing diaminoresorcin and terephthalic acid in polyphosphoric acid by dry and wet. The main point is that the PBO (poly p-phenylene benzobisoxazole) fiber is used.

  According to such a feature, the PBO fiber expresses about twice the strength of the conventional para-aramid fiber, so that the strength and elastic modulus of the protective layer can be increased, and the cut resistance can be improved more reliably. be able to.

  According to the present invention, for example, in a high-speed heavy-duty pneumatic radial tire that is mounted on an aircraft or the like and rotated at a high speed while being loaded with a heavy load, the strength of the protective layer cord is increased and the cut resistance is improved. The workability of the protective layer during production can be improved.

(Configuration of pneumatic radial tire for high speed heavy load)
A high-speed heavy-duty pneumatic radial tire according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a high-speed heavy-load pneumatic radial tire according to this embodiment.

  In the figure, a pneumatic radial tire 11 is a pneumatic radial tire for high-speed heavy loads that is mounted on an aircraft or the like, and a tread portion 15 (tread rubber layer) that serves as a contact portion with a road surface, and a covering of the tread portion 15. A belt layer 29 (main belt) is disposed between the carcass layer 21 embedded in rubber.

  The pneumatic radial tire 11 includes a pair of bead portions 13 each having a bead core 12 embedded therein, and sidewall portions 14 formed from the bead portions 13 toward the outer side in the tire radial direction.

  The carcass layer 21 is a toroid-shaped reinforcing member that extends from one bead portion 13 to the other bead portion 13. The carcass layer 21 is composed of two or more carcass plies 22 that overlap each other, in this embodiment, six layers of carcass plies 22. Of the carcass ply 22, four layers on the inner layer side are turned up around the bead core 12, and two layers on the outer layer side are extended to the bead core 12 along the outer side of the folded portion. Down ply.

  A tread rubber layer 26 is disposed on the outer side of the carcass layer 21 in the tire radial direction, and a plurality of circumferential grooves 27 extending along the tire circumferential direction are formed in the tread rubber layer 26. In the present embodiment, a belt cord made of a large number of nylon fibers or aramid fibers that are substantially orthogonal to the tire equator line E (extends in the radial direction) is embedded in the carcass ply 22.

  Furthermore, in this embodiment, as shown in FIG. 1, end portions in the tread width direction of the belt layer 29, specifically, both side end portions in the tread width direction of the belt ply 31 located on the innermost side in the tire radial direction, An interposed rubber 45 extends continuously in the circumferential direction between the carcass layer 21, specifically, the outermost carcass ply 22. The thickness of the interposed rubber 45 provided at both end portions in the tread width direction becomes thinner toward the inner side in the tread width direction. In the present embodiment, a separation member 46 is interposed between the belt layer 29 and the protective layer 35.

  The protective layer 35 is located on the outer side in the tire radial direction from the belt layer 29 and covers the belt layer 29. On the other hand, as shown in FIG. 1, the belt layer 29 is an annular member disposed between the carcass layer 21 and the tread rubber layer 26, and the belt layer 29 (main belt) according to this embodiment is a tire. The belt ply is composed of a plurality of layers laminated in the radial direction. The plurality of belt plies include a four-layer belt ply 31 located on the side close to the carcass layer 21 and a four-layer belt ply 32 disposed on the outer side in the tire radial direction.

  The belt ply 31 and the belt ply 32 are configured by arranging a plurality of belt cords formed of Kevlar fibers or the like and covered with rubber.

  Further, the belt layer 29 has a belt layer tensile breaking strength which is a tensile breaking strength of the belt layer 29 of 6.3 cN / dtex or more, and an elongation rate under a load of 0.3 cN / dtex in the extension direction of the belt layer 29. 0.2 to 2.0%, the elongation at the time of 2.1 cN / dtex in the stretching direction is 1.5 to 7.0%, and the elongation at the time of 3.2 cN / dtex in the stretching direction is 2. 2 to 9.3%.

  In contrast, the protective layer 35 has a tensile breaking strength equal to or higher than the belt layer tensile breaking strength.

  Further, the protective layer 35 is formed by winding a belt-like body 33 (not shown in FIG. 1) having a ribbon-like shape around the belt layer 29 in a spiral manner.

  Further, the belt layer 29 has a thickness at the central portion in the tread width direction of the belt layer 29 as “G0” and a thickness at a width position that is 2/3 of the maximum width of the belt layer 29 from the central portion as “G2”. In addition, these relationships are 0.35 ≦ G2 / G0 ≦ 0.85.

  A separation member 46 is provided between the protective layer 35 and the belt layer 29 to separate the protective layer 35 and the belt layer 29 from each other with a predetermined interval. In the present embodiment, the separation member 46 is made of a rubber-based material having a thickness of 2.0 to 5.0 mm.

  FIG. 2 is a partial front view showing the configuration of the protective layer 35 according to the present embodiment. FIG. 2 is a view in which the protective layer 35 positioned on the inner side in the tire radial direction from the tread rubber layer 26 is captured from the direction facing the tread surface of the pneumatic radial tire 11. In the present embodiment, the protective layer 35 is formed by winding the belt-like body 33 around the belt layer 29 in a spiral shape, and has a so-called spiral shape.

  In the present embodiment, the angle formed by the outer contour line in the longitudinal direction at the winding start portion of the ribbon-like body 33 and the tire equator line E is approximately 0 degrees, that is, substantially parallel to the tire equator line E. . In addition, the ribbon-like body 33 is not joined to the new ribbon-like body 33 in the middle of covering the belt layer 29, and one ribbon-like body 33 is continuously formed from the start to the end of winding. The belt layer 29 is wound around.

  The ribbon 33 is wound around the belt layer 29 while gradually moving in the tread width direction so that a gap is not generated between the wound ribbons 33 every time the circumferential direction of the belt layer 29 is made. It is done.

  As shown in FIG. 1, in the present embodiment, the pneumatic radial tire 11 is composed of one protective layer 35, but may be composed of a plurality of protective layers 35.

  FIG. 3 is a schematic configuration diagram of the ribbon-like body 33. As shown in the figure, the ribbon-like body 33 is configured by arranging a plurality of organic fiber corrugated belt cords 33a extending in a corrugated shape along the tire circumferential direction. Each corrugated belt cord 33a is coupled by a coupling rubber 33b.

  The belt cord used for the ribbon-like body 33 is not limited to the wave-like belt cord 33a. For example, a zigzag belt cord may be used instead of the wave-like belt cord 33a.

  The ribbon-like body 33 is coated with a resin extruded at a high temperature, and the protective layer 35 is formed by winding the ribbon-like body 33 on the separation member 46.

In the present embodiment, PBO (poly p-phenylene benzobisoxazole) fibers represented by xylon (trade name) and the like are used as the material of the protective layer 35 (specifically, the material of the wavy belt cord 33a). ing. PBO fiber is one of polybenzazoles, which are heterocycle-containing polymers. As shown in the chemical formula below, PBO fiber is wet and dry against a polymer dope obtained by polymerizing diaminoresorcin and terephthalic acid in polyphosphoric acid. Manufactured by spin spinning, and has about twice the strength and elastic modulus of para-aramid.

  The physical characteristics of this PBO fiber are higher in strength and elastic modulus than the conventional fiber, as can be seen from the stress-strain curve shown in FIG. 4, and as shown in the TGA chart of FIG. The decomposition temperature is 650 ° C., which is about 100 ° C. higher than that of para-aramid fiber.

  Further, the mechanical properties due to heat resistance of the PBO fiber show an elastic modulus of 70% at room temperature even at 400 ° C., as shown in FIG. The value shown in FIG. 6 is a storage elastic modulus measured using a dynamic viscoelasticity measuring apparatus. As shown in FIG. 7, the temperature dependence of the strength is confirmed to decrease linearly as the temperature rises, but the strength of 40% of the room temperature is maintained even at 500 ° C. As an organic fiber, high heat resistance is ensured.

  Furthermore, it shows in FIG. 8 about the dimensional stability of a PBO fiber. FIG. 8 shows the measurement results of room temperature creep under a 50% load of the tensile strength. As shown in the figure, the creep rate of the PBO fiber becomes a value of 1/2 or less under a load nearly twice that of the para-aramid fiber. In addition, as shown in FIG. 9, the chemical stability of the PBO fiber is as resistant to acid as the para-aramid fiber even at room temperature. In the bleaching agent, as shown in FIG. In contrast to complete degradation, the PBO fibers are found to be stable with a strength of 90% or more after 300 hours.

The characteristics of the PBO fibers described above are summarized as shown in Table 1 below.

(Operation and effect of pneumatic radial tire for high speed heavy load)
According to the pneumatic radial tire for high speed and heavy load according to the present embodiment described above, the protective layer 35 for protecting the belt layer 29 is formed by spirally winding the ribbon-like body 33, so that the tensile breaking strength of the protective layer 35 is increased. Even in the case of using a hard, low-flexible belt cord or the like to increase the workability of the protective layer 35, the workability of the protective layer 35 can be improved.

  Further, by making the protective layer 35 spirally wound, the adhesiveness between the protective layer 35 and the tread rubber layer 26 can be improved, and the joint portion formed at the end portion of the belt cord or the like is eliminated. It is possible to suppress failures such as separation and peel-off that have occurred in the portion and improve durability.

  In this embodiment, the belt layer 29 has a tensile strength at break of 6.3 cN / dtex, which is the tensile strength at break of the belt layer 29, and the elongation at the time of load of 0.3 cN / dtex in the extension direction of the belt layer 29 is 0.2 to 2.0%, the elongation at the time of 2.1 cN / dtex in the stretching direction is 1.5 to 7.0%, and the elongation at the time of 3.2 cN / dtex in the stretching direction is 2. The tensile breaking strength of the protective layer 35 is the tensile breaking strength of the belt layer 29 or higher.

  As a result, while maintaining the required pressure resistance performance of the pneumatic radial tire 11, it is possible to suppress the growth in the tire radial direction at the time of filling the tire internal pressure, and to prevent the cut resistance of the pneumatic radial tire 11 from being lowered. .

  Furthermore, in the belt layer 29 according to the present embodiment, the thickness “G0” of the belt layer 29 in the center portion in the tread width direction and the thickness in the width position of 2/3 of the maximum width of the belt layer 29 from the center portion in the tread width direction. The relationship with “G2” is 0.35 ≦ G2 / G0 ≦ 0.85.

  For this reason, it is possible to prevent the belt cord or the like located near the shoulder portion of the pneumatic radial tire 11 from being subjected to an excessive tension, and to prevent the pressure resistance performance from being lowered. In addition, it is possible to effectively utilize the belt layer disposed at the width position of 2/3 of the maximum width of the main belt. In other words, when G2 / G0 exceeds 0.85, the belt layer disposed at the position is not effectively utilized, and the weight of the pneumatic radial tire for high-speed heavy load increases as the belt layer at other positions is strengthened. However, this increase in weight can be suppressed.

  In the present embodiment, since the PBO fiber represented by xylon or the like is used as the belt cord (corrugated belt cord 33a) forming the protective layer 35, the strength and elastic modulus of the protective layer 35 can be increased. Thus, the cut resistance can be improved more reliably.

  Further, in the present embodiment, since the separation member 46 is interposed between the protective layer 35 and the belt layer 29, the protective layer 35 and the belt layer 29 are maintained while keeping the distance between the protective layer 35 and the belt layer 29 constant. And the adhesiveness can be increased. Further, at the time of manufacture, a belt cord coated with a resin extruded at a high temperature can be wound around the separation member 46, and the belt cord can be molded in a hot state for protection. The workability in forming the layer 35 can be further enhanced.

(Test results)
Next, the test results of the pneumatic radial tire 11 which is the pneumatic tire for high speed heavy load according to the present embodiment described above will be described. In the test, a conventional high-speed heavy-duty pneumatic tire having the specifications shown in Table 2 (conventional example), a comparative example, and a high-speed heavy-duty pneumatic tire according to the present embodiment (example) were used. And a T / O test.

  In the cut resistance test, the center part of the tread of a high-speed heavy-duty pneumatic tire that rotates at a speed of 20 km / h is stepped on a cutter with a sharp edge of 30 mm in height and 300 mm in width. The tread depth (cut depth) was measured.

  In the T / O test, under normal internal pressure and load conditions, the rotational speed of the pneumatic tire for high speed and heavy load is increased over about 1 minute until reaching the rotational speed corresponding to 380 km / h, peel off, etc. The presence or absence of occurrence was confirmed.

  As a result, in the cut resistance test, the cut resistance of Examples and Comparative Examples (band winding) was good. Moreover, in the T / O test, the examples and comparative examples (spiral winding) were in a good state with no occurrence of peel-off or the like.

1 is a cross-sectional view of a high-speed heavy-load pneumatic radial tire according to an embodiment of the present invention. It is a partial front view which shows the structure of the protective layer which concerns on embodiment of this invention. It is a block diagram of the ribbon-shaped body which forms the protective layer which concerns on embodiment of this invention. It is a graph which shows the stress-strain curve of a PBO fiber. It is a graph which shows the decomposition | disassembly behavior by the thermo mass analysis of PBO fiber. It is a graph which shows the temperature change of the storage elastic modulus of a PBO fiber. It is a graph which shows the temperature change of the tensile strength of a PBO fiber. It is a graph which shows the creep characteristic of a PBO fiber. It is a graph which shows the intensity | strength retention after immersion of the concentrated sulfuric acid (60%) of a PBO fiber. It is a graph which shows the strength retention after immersion of the sodium hypochlorite aqueous solution of PBO fiber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Pneumatic radial tire, 12 ... Bead core, 13 ... Bead part, 14 ... Side wall part, 15 ... Tread part, 21 ... Carcass layer, 22 ... Carcass ply, 26 ... Tread rubber layer, 27 ... Circumferential groove, 29 ... belt layer, 31, 32 ... belt ply, 33 ... ribbon-like body, 33a ... corrugated belt cord, 33b ... binding rubber, 35 ... protective layer, 45 ... interposition rubber, 46 ... separation member, E ... tire equator line

Claims (5)

A main belt is disposed between a tread rubber layer serving as a ground contact portion with a road surface and a carcass layer embedded in a covering rubber positioned on the inner side in the tire radial direction from the tread rubber layer, and the outer side in the tire radial direction from the main belt. In a pneumatic radial tire for high speed heavy load having a protective layer covering the main belt
The protective layer is formed by continuously winding a ribbon-like body having a ribbon-like shape around the main belt,
The high-speed heavy-load pneumatic radial tire is characterized in that the ribbon-like body is formed by arranging a plurality of organic fiber belt cords extending in a wavy or zigzag shape along a tire circumferential direction. The main belt tensile rupture strength, which is the tensile rupture strength of the main belt, is 6.3 cN / dtex or more, and the elongation rate at a load of 0.3 cN / dtex in the extension direction of the main belt is 0.2-2. 0%, elongation at 2.1 cN / dtex in the direction of elongation is 1.5 to 7.0%, and elongation at 3.2 cN / dtex in the direction of elongation is 2.2 to 9.3% And
The pneumatic radial tire for high-speed heavy loads according to claim 1, wherein the protective layer has a tensile breaking strength equal to or higher than the main belt tensile breaking strength. When the thickness of the main belt at the central portion in the tread width direction of the main belt is G0, and the thickness at the width position of 2/3 of the maximum width of the main belt from the central portion is G2, these relationships are:
0.35 ≦ G2 / G0 ≦ 0.85
The pneumatic radial tire for high-speed heavy loads according to claim 1. Between the protective layer and the main belt, a separation member is provided for separating the protective layer and the main belt at a predetermined interval,
2. The high-speed heavy-duty pneumatic radial tire according to claim 1, wherein the protective layer is formed by winding a belt cord coated with a resin extruded at a high temperature around the separation member.   The organic fiber is a PBO (poly p-phenylene benzobisoxazole) fiber formed by spinning a polymer dope obtained by polymerizing diaminoresorcin and terephthalic acid in polyphosphoric acid by dry and wet processes. The pneumatic radial tire for high-speed heavy loads according to claim 1.

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