JP2013063728A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for improving side-cut resistance performance of a pneumatic tire used especially as a tire for a heavy load.SOLUTION: The pneumatic tire includes a pair of right and left bead portions 11 and side wall portions 12, and a tread part 13 continuing between both of the side wall portions, and includes a carcass 2 as a skeleton formed of at least one carcass ply extending over between the pair of the bead portions in a toroidal shape. A reinforcing member 5, which is formed of reinforcing fibers treated with plating or adhesive and rubber for covering the reinforcing fibers, is arranged on an outer side of the side wall portion in a tire width direction of the carcass ply. The reinforcing fibers are oriented substantially in a tire circumferential direction. At least one end of the reinforcing fibers is terminated within the reinforcing member, and two or more reinforcing fibers are overlapped at least partially in a projection image in which the reinforcing fiber is projected in the tire width direction.

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly, to a heavy duty pneumatic tire used in heavy duty vehicles such as trucks and buses.

  Conventionally, in a pneumatic tire, reinforcement has been carried out by arranging a reinforcing member formed by aligning organic fiber cords or steel cords in a certain direction and rubberizing at each part from the bead portion to the tread portion. It has been broken. For example, Patent Document 1 discloses that a side reinforcing layer formed by impregnating a rubber component in an organic fiber cord is disposed between a carcass layer and a belt layer of a sidewall.

  Further, as an improved technique for reinforcing the sidewall portion, for example, Patent Document 2 discloses a pneumatic radial tire in which a fiber reinforcing member in which a nonwoven fabric made of monofilament fibers is covered with rubber is installed in the vicinity of the carcass layer. Patent Document 3 discloses a pneumatic radial tire in which a reinforcing layer formed by covering a nonwoven fabric with rubber is provided inside and outside the radial width of the radial carcass, and the radial carcass is sandwiched between these reinforcing layers. It is disclosed. Furthermore, Patent Documents 4 and 5 disclose pneumatic safety tires in which rubber-filament fiber composites are disposed on the sidewall portions in order to improve run-flat running performance. Furthermore, in Patent Document 6, a steel filament is provided in at least a part of a region outside the carcass and extending from the belt layer end to the outer end in the tire radial direction of the bead filler. There is disclosed a pneumatic tire provided with a rubber-steel filament composite layer that is dispersed and embedded in at least two directions.

JP 2006-142877 A (Claims etc.) JP-A-8-40023 (Claims etc.) JP 2002-331808 A (Claims etc.) JP-A-11-129712 (Claims etc.) Japanese Patent Laid-Open No. 11-240307 (claims, etc.) JP 2011-1111050 A (Claims etc.)

  By the way, with respect to sidewall portions, car car plies often break down in passenger car tires. There are many troubles caused by entering. This is because a heavy duty tire has a larger air pressure and load applied to the carcass cord than a passenger tire. Therefore, although the purpose of reinforcing the sidewall portion is different between the tire for a passenger car and the heavy load tire, conventionally, a study on a reinforcing member paying attention to such a point has not been sufficiently performed.

  Therefore, an object of the present invention is to provide a technique for solving the above-described problems and improving the side cut resistance more particularly in a pneumatic tire used as a heavy duty tire.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by arranging a reinforcing member having a specific structure using a reinforcing fiber that satisfies a predetermined condition in the sidewall portion, and the present invention has been completed. It came to do.

That is, the present invention has a pair of left and right bead portions and sidewall portions, and a tread portion continuous between both sidewall portions, and at least one sheet extending in a toroid shape between the pair of bead portions. In a pneumatic tire having a carcass ply made of carcass ply,
A reinforcing member comprising a reinforcing fiber plated or adhesive-treated and a rubber covering the reinforcing fiber is disposed outside the side wall portion of the carcass ply in the tire width direction. Are substantially oriented in the tire circumferential direction, at least one end of the reinforcing fiber is terminated in the reinforcing member, and two or more of the reinforcing fibers are in a projected part in which the reinforcing fiber is projected in the tire width direction. It is characterized by overlapping at least partly.

In the present invention, the weight density of the reinforcing member is preferably 50 g / m ² or more and 1500 g / m ² or less. In the present invention, the length of the reinforcing fiber is preferably in the range of 10 mm to 80 mm. Furthermore, in the present invention, the diameter of the reinforcing fiber is preferably in the range of 0.07 mm to 0.60 mm. Furthermore, inorganic fibers can be suitably used as the reinforcing fibers.

  According to the present invention, by adopting the above-described configuration, it is possible to realize a pneumatic tire, particularly a heavy-duty pneumatic tire, which has further improved side-cut resistance compared to the conventional art.

1 is a cross-sectional view in the width direction showing a heavy duty pneumatic tire as an example of the pneumatic tire of the present invention. It is a schematic diagram which shows an example of the reinforcement member which concerns on this invention. It is a schematic diagram which shows the dispersion state of the reinforcing fiber in a comparative example.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows a cross-sectional view in the width direction of a heavy duty pneumatic tire as an example of the pneumatic tire of the present invention. The illustrated tire includes a pair of left and right bead portions 11, a sidewall portion 12 that extends outward in the tire radial direction from the bead portion 11, and a tread portion 13 that is continuous between both sidewall portions 12. A carcass 2 composed of a single carcass ply extending in a toroid shape between a pair of bead cores 1 embedded in the bead portion 11 is used as a skeleton. Further, at least two, in the illustrated example, three belt layers 3 and a belt protective layer 4 are sequentially disposed on the outer side in the tire radial direction of the crown portion of the carcass 2.

  In the tire of the present invention, the reinforcing member 5 made of reinforcing fibers and rubber covering the reinforcing fibers 5 is annularly formed in the tire circumferential direction in at least a part of the side wall portion 12 outside the carcass ply in the tire width direction. It is characterized in that it is disposed. FIG. 2 is a schematic view showing an example of a reinforcing member according to the present invention. This figure shows a dispersion state of the reinforcing fibers when viewed from a direction perpendicular to the surface of the reinforcing member. As shown in the figure, the reinforcing member according to the present invention includes reinforcing fibers 21 plated with adhesive or an adhesive and rubber 22. Further, the reinforcing fiber 21 is oriented in one direction as shown, and at least one end thereof terminates in the reinforcing member, that is, has a length that does not continuously extend between the widthwise ends of the reinforcing member. Made of short fibers. Further, as shown in the drawing, the reinforcing fiber 21 has two or more projection parts when the reinforcing fiber 21 is projected in the tire width direction, that is, the projection part when the reinforcing member is viewed from the outer surface side of the sidewall part 12. The reinforcing fibers 21 are embedded in the rubber 22 so as to overlap at least partly. The reinforcing member according to the present invention has a planar shape having a thickness.

  By adopting such a configuration, it has become possible to use the end material that has conventionally become waste as the reinforcing fiber 21 of the reinforcing member, and it has become possible to effectively use the waste material. In addition, unlike the conventional cord reinforcing layer, the reinforcing member according to the present invention does not require a process such as a stranded wire or draw rolling, and thus is easy to manufacture, and is excellent in cost. ing. Furthermore, in the reinforcing member according to the present invention, since the cross-sections of the reinforcing fibers do not line up at the end portions, there is no problem of separation starting from the reinforcing member end portions.

  In the present invention, as shown in the drawing, a reinforcing member in which the reinforcing fibers 21 are oriented substantially in one direction is used, and the reinforcing members are arranged so that the orientation direction of the reinforcing fibers 21 is the tire circumferential direction. As described above, by using the reinforcing member in which the reinforcing fibers 21 are substantially oriented in the tire circumferential direction, the side cut resistance is improved, and cracks are generated from between the carcass cords, which is peculiar in heavy duty tires. This makes it possible to effectively suppress the occurrence of failures. Therefore, in the present invention, due to the effect of improving the side cut resistance due to the arrangement of the reinforcing member, the side cut resistance is remarkably increased even when the sidewall portion is made thinner to reduce the weight of the tire. The decrease can be suppressed. That is, in this case, it is possible to reduce the cost while maintaining the tire performance by using the reinforcing member using the waste material having no direct material cost while reducing the amount of rubber used in the tire.

Here, in the present invention, the fact that the reinforcing fibers 21 are substantially oriented in the tire circumferential direction means that a certain degree of distribution occurs in the orientation direction of the reinforcing fibers 21 in the production of the reinforcing member. It means that the error range is included. Specifically, for example, a range within ± 60 ° is preferable as an angle formed by the orientation direction of the reinforcing fiber 21 with respect to the tire circumferential direction, and more preferably within ± 20 °. It is. Considering only the improvement of the side cut resistance, it is most preferable that the orientation direction of the reinforcing fiber 21 is 0 ° with respect to the tire circumferential direction, but in this case, the extensibility at the time of molding deteriorates. In fact, the above-mentioned angle is preferably in the range of 10 to 20 ° because other problems such as shortening of the shoulder contact length may occur. In the present invention, since the reinforcing fibers 21 are substantially oriented in the tire circumferential direction, the arrangement length of the reinforcing fibers 21 in the tire radial direction is within 30 mm. The orientation of the reinforcing fiber can be evaluated based on the value of the standard deviation θσ of the angle θi formed by the orientation direction of the reinforcing fiber in the reinforcing member and the direction corresponding to the tire circumferential direction. The average value θave and the standard deviation θσ of the angle θi are calculated based on the following equations, respectively. If this standard deviation θσ is within 15 °, the orientation is good.

In the present invention, it is preferable to use a reinforcing member having a basis weight density of 50 g / m ^{2 to} 1500 g / m ² , particularly 300 g / m ^{2 to} 1000 g / m ² . When the basis weight is less than 50 g / m ² , the rigidity of the reinforcing member is lowered, and the side cut resistance performance is lowered. On the other hand, if the basis weight exceeds 1500 g / m ² , there is a possibility that breakage due to fretting of the reinforcing fibers and wild wires may occur. Here, in the present invention, the basis weight density of the reinforcing member means the total weight of the reinforcing fibers per unit area in one layer of the reinforcing member. That is, the total weight (g) of the reinforcing fibers 21 per layer of the reinforcing member included per unit area (1 m ² ) is the basis weight density in the present invention.

  The diameter of the reinforcing fiber is preferably 0.07 mm to 0.60 mm, particularly 0.12 mm to 0.34 mm. If the diameter of the reinforcing fiber is too small, the cost in the wire drawing process for obtaining a thin wire diameter increases, and the number of reinforcing fibers to be spread increases, resulting in an increase in cost. On the other hand, if the diameter of the reinforcing fiber is too large, the bending rigidity increases and the longitudinal spring increases.

  Further, the length of the reinforcing fiber is preferably in the range of 10 mm to 80 mm, and particularly preferably 25 mm to 50 mm. If the length of the reinforcing fiber is too short, the man-hour for cutting increases. On the other hand, if the length of the reinforcing fiber is too long, the moldability deteriorates.

  In the present invention, it is not necessary for all the reinforcing fibers used for the reinforcing member to have a single length and diameter, and a mixture of reinforcing fibers having a plurality of types of lengths and diameters may be used. It is preferable to use a material having a length and diameter within the above range. In particular, if the length of the reinforcing fiber is too long, the uniformity of the reinforcing member is impaired, which is not preferable because the uniformity of the tire shape and the tire rigidity in the circumferential direction, which is a component that determines uniformity, is deteriorated. In addition, the cross-sectional shape of the reinforcing fiber is basically circular, but a polygonal shape such as an ellipse or a triangle may be used.

  The region where the reinforcing member is disposed in the sidewall portion may be at least a part of the region from the end of the belt layer 3 to the vicinity of the upper end of the bead core 1, but preferably along the carcass ply, It arrange | positions in the range from the position which overlaps with the arrangement | positioning area | region of cushion rubber about 10 mm to the position which overlaps the arrangement | positioning area | region of stiffener rubber 6 and about 10 mm. Thereby, the side cut resistance of the whole side wall part can be improved.

  In the present invention, any material may be used as the reinforcing fiber, and it can be appropriately selected from various materials usually used for tire reinforcing members. Specifically, for example, inorganic fibers include metal fibers such as steel filaments and glass fibers, and organic fibers include aromatic polyamide fibers, fatty acid polyamide fibers, polyester fibers, polyparaphenylenebenzeneoxazole fibers, and polyvinyl alcohol-based synthetics. Examples thereof include fibers and carbon fibers. In the present invention, among the above, it is preferable to use inorganic fibers, particularly steel filaments, as the short fibers.

  The above-mentioned reinforcing fibers made of inorganic fibers or organic fibers are used in the manufacturing process of tire reinforcing cords, such as end materials (waste made from residual yarn) generated in the post-plating wire drawing process or stranded wire process, It can be manufactured from mill ends generated in the cord rolling process. In the present invention, since such a conventionally discarded scrap material can be used, the cost can be greatly reduced as compared with the conventional one, and the waste can be reduced. is there.

  That is, a metal cord such as a steel cord is manufactured by unwinding a filament from a plurality of reels around which a single filament wire subjected to a plating process is wound, and twisting a filament bundle using tension. A non-metallic cord made of organic fibers or the like is manufactured by performing a dipping process in which an adhesive is applied to a twisted filament bundle. When manufacturing a metal twisted cord, when any one of the reels is emptied, the remaining filaments are discarded even if they remain on the other reels. Also, the adjustment portion at the end of the cord is discarded when the manufacturing process is stopped for adjustment and then restarted. Furthermore, since both the metal cord and the non-metallic cord use the tension to manufacture the reinforcing member, the cord end portion that cannot physically secure the tension is also discarded. In the present invention, the reinforcing member can be formed by effectively using the end material of the cord generated in each process in manufacturing the tire.

  In addition, the technique which improves on-ice performance by containing the very micro fiber about 5.0 mm or less in length, usually 2 mm-3 mm in a tread rubber as a short fiber is known well conventionally. However, in consideration of the effective use of the waste material as described above, if the end material of the cord is cut into micro short fibers and used, the number of manufacturing steps and cost increase. In the present invention, if the reinforcing fibers to be used do not have a certain length and basis weight, the reinforcing fibers do not intersect with each other, or even if they intersect, a sufficient reinforcing effect on strength and rigidity cannot be obtained. Therefore, it is preferable to use a reinforcing fiber having the above length, basis weight density, and the like. However, if only short reinforcing fibers or only long reinforcing fibers are used, a sufficient reinforcing effect may not be obtained or there may be a problem in durability.

  Moreover, since the said reinforcing fiber is embed | buried in rubber | gum and forms a reinforcement member, in order to ensure adhesiveness with rubber | gum, it needs to be plated or adhesive-treated. That is, in the present invention, when the reinforcing fiber is a metal fiber, a plated one is used, and when the reinforcing fiber is an organic fiber, an adhesive-treated one is used. In a metal fiber such as a steel filament, for example, when general Cu + Zn plating is performed, Cu during plating plays a role of adhering rubber and reinforcing fiber when forming a reinforcing member. When the surface of the metal cord is not plated, the rubber and the reinforcing fiber are easily peeled off, and there is a concern that the progress of peeling easily occurs along the reinforcing fiber. Accordingly, in the present invention, when metal fibers are used as the reinforcing fibers, it is necessary to use plated ones, and even when a stranded wire cord is used as a raw material, single wires must be plated. is there. When the metal cord is made of a copper wire, the copper wire itself has an adhesive effect, so that plating is not necessary. In addition, in the case of non-metallic cords made of organic fibers, etc., by using an adhesive dipped in accordance with a conventional method, as with plated metal cords, adhesion to rubber is ensured. Is possible.

  Here, there is no restriction | limiting in particular as plating provided in the metal fiber surface as a reinforcement fiber, Brass, bronze, Cu, Zn plating, etc. may be sufficient. In particular, when the above-mentioned waste scraps are used as the reinforcing fibers, since these are already plated, there is an advantage that good adhesion to rubber can be obtained without further plating.

  The rubber used for the reinforcing member can be appropriately selected from rubber types conventionally used for tire reinforcing member applications, and is not particularly limited. Moreover, there is no restriction | limiting in particular about the thickness of reinforcement member itself, Although it can determine suitably according to the target reinforcement performance, For example, it is 3.0 mm or less, Preferably you may be 0.8-1.5 mm. be able to.

The reinforcing member in which the reinforcing fibers are oriented substantially in one direction as described above can be manufactured, for example, as follows.
That is, first, a sheet of unvulcanized rubber having a predetermined thickness is prepared, and a bundle of reinforcing fibers cut to a predetermined length is entirely transferred onto the rubber sheet from a predetermined amount and a predetermined height on the rubber sheet. Drop to a uniform density. At this time, a guide body having a portion that opens in the vertical direction above the rubber sheet, has a width along the longitudinal direction of the rubber sheet that is narrower at the lower end than the upper end, and gradually decreases from the upper end toward the rubber sheet. The reinforcing fiber is dropped on the rubber sheet through the guide body. As a result, the reinforcing fibers fall on the rubber sheet in a state of being oriented in the width direction of the rubber sheet along the shape of the lower opening of the guide body, so that the reinforcing fibers are substantially oriented in one direction. The reinforcing member which is made can be obtained. The guide body also has an effect of preventing the density of the reinforcing fibers that are blown off from being dispersed more widely than necessary, and can be designed according to the width of the rubber sheet disposed below. In particular, the guide body preferably has a portion where the width does not vary following the portion where the width along the longitudinal direction of the rubber sheet gradually decreases, thereby more reliably orienting the reinforcing fibers. be able to.

  Next, an unvulcanized rubber sheet is placed on the dropped reinforcing fiber, whereby a reinforcing member in which the reinforcing fiber is embedded in the rubber can be manufactured. At this time, by moving the lower rubber sheet in one direction at a predetermined speed, the density of the reinforcing fiber in the reinforcing member can be determined by the ratio of the amount of the reinforcing fiber falling and the moving speed of the rubber sheet. it can.

  Here, as a method for dropping the predetermined amount of reinforcing fibers, a bundle of reinforcing fibers cut in advance is transported by a belt conveyor or the like and dropped onto a predetermined portion on the rubber sheet, as well as uncut. A method of dropping the reinforcing fiber while cutting may be used. In the latter case, the work of untangling the reinforcing fibers and the work of supplying a bundle of reinforcing fibers in a constant amount at a constant time are not required, and therefore the reinforcing member can be manufactured more efficiently.

  Since the reinforcing member according to the present invention can be easily manufactured in one process as described above, it is easier to manufacture and consumes less energy than a conventional reinforcing member that requires a large number of steps for manufacturing. There is an advantage that the manufacturing cost is low.

  In the tire of the present invention, it is only important that the reinforcing member is arranged such that the orientation direction is the tire radial direction, and other details of the tire structure and the material of each member are not particularly limited. It can be configured by appropriately selecting from conventionally known ones.

  For example, the carcass 2 is made of rubber coated steel cord, and it is necessary to arrange at least one piece. However, two or more pieces may be arranged, and usually around the bead core 1 as shown in the figure. The tire is folded back from the inside to the outside and locked. Further, the belt layer 3 is formed by rubber-covering a plurality of steel cords arranged in parallel at an angle of, for example, 15 to 55 ° with respect to the tire circumferential direction, and is three in the illustrated example. However, usually at least two sheets are arranged so as to cross each other. Furthermore, one or more belt protective layers 4 can be disposed on the outer side of the belt layer 3 in the tire radial direction.

  Further, in the illustrated tire, a tread pattern is appropriately formed on the surface of the tread portion 13, and an inner liner (not shown) is formed in the innermost layer. Moreover, as gas with which a tire is filled, normal or air with changed oxygen partial pressure, or inert gas such as nitrogen can be used.

Hereinafter, the present invention will be described in more detail with reference to examples.
Stiffener rubber at a tire size of 275 / 80R22.5 from a position overlapping the cushion rubber (not shown) region by about 10 mm along the carcass ply on the outer side in the tire width direction of the carcass ply on the side wall. Reinforcing members satisfying the conditions shown in the following table are annularly arranged in the tire circumferential direction in a range up to a position that overlaps with the arrangement region of about 10 mm, and the heavy duty pneumatic tires of the examples and comparative examples are Produced. This reinforcing member was composed of a steel filament plated according to a conventional method and a rubber covering the steel filament, and the thickness was 1.0 mm. In each embodiment, the steel filament does not continuously extend between the end portions in the width direction of the reinforcing layer, that is, at least one end thereof terminates in the reinforcing layer, and the steel filament extends in the tire width direction. In the projected portion, the two or more reinforcing fibers overlapped at least partially.

  One carcass ply (cord material: steel cord) was used. Also, the belt layer (cord material: steel cord) is 3 sheets, and 1 to 3 belts from the inside in the tire radial direction, respectively, 52 ° (1 belt) and 18 ° (2, 3 belts) with respect to the tire circumferential direction The crossing was arranged sequentially at an angle of.

Further, as Conventional Example 1, a tire without a reinforcing member was produced.
Each of the obtained test tires was evaluated according to the following. The results are also shown in the table below.

<Side cut resistance>
The side cut resistance of each test tire was evaluated by measuring the load at which a failure occurred by changing the load when the tire was brought into contact with the protrusion in an actual vehicle test. The results are shown as an index with the load at which the failure of the test tire of Conventional Example 1 occurs as 100.

＊１）図３に示すような補強繊維の分散状態を意味する。

* 1) Means a dispersed state of reinforcing fibers as shown in FIG.

  From the results in the above table, in the test tires of the respective examples in which the reinforcing members satisfying the conditions of the present invention are arranged in the sidewall portions, the side cut resistance is compared with the tire of the conventional example 1 in which no reinforcing member is arranged. It was confirmed that the performance was improved. On the other hand, in the test tire of Comparative Example 1 in which the reinforcing fibers were randomly arranged, sufficient side cut resistance was not obtained.

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass 3 Belt layer 4 Belt protective layer 5 Reinforcement member 6 Stiffener rubber 11 Bead part 12 Side wall part 13 Tread part 21 Reinforcing fiber 22 Rubber

Claims (5)

A carcass composed of at least one carcass ply having a pair of left and right bead portions and sidewall portions, and a tread portion continuous between the two sidewall portions, and extending in a toroid shape across the pair of bead portions. In the pneumatic tire as a framework,
A reinforcing member comprising a reinforcing fiber plated or adhesive-treated and a rubber covering the reinforcing fiber is disposed outside the side wall portion of the carcass ply in the tire width direction. Are substantially oriented in the tire circumferential direction, at least one end of the reinforcing fiber is terminated in the reinforcing member, and two or more of the reinforcing fibers are in a projected part in which the reinforcing fiber is projected in the tire width direction. A pneumatic tire characterized by overlapping at least partly. The pneumatic tire according to claim 1, wherein the weight density of the reinforcing member is 50 g / m ² or more and 1500 g / m ² or less.   The pneumatic tire according to claim 1 or 2, wherein a length of the reinforcing fiber is in a range of 10 mm to 80 mm.   The pneumatic tire according to any one of claims 1 to 3, wherein a diameter of the reinforcing fiber is in a range of 0.07 mm to 0.60 mm.   The pneumatic tire according to any one of claims 1 to 4, wherein the reinforcing fiber is an inorganic fiber.

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