JP2010006365A - Automotive tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automotive tire capable of reducing the influence of a magnetic field arising from the magnetization of steel cords used as a reinforcement for a belt layer. <P>SOLUTION: In a crown region of a carcass 11, a plurality of layered steel belts 13 are provided. Each of the steel belts 13 is configured to cover a plurality of steel cords 15 with rubber. An outer-circumferential surface of the steel belt 13 on an outermost layer in the tire radial direction R has a tread 17. The tread 17 includes two layers composed of an inner under tread 18 inside in the tire radial direction R and a cap tread 19 laminated on the outer-circumferential surface of the under tread. At least one of rubber constituting the steel belts 13, the under tread 18 and the cap tread 19 is formed of rubber containing a high permeability material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an automobile tire having a steel belt formed by coating a plurality of steel cords with rubber, and more particularly, to an automobile tire in which the magnetism generated from the steel cord is shielded from leaking outside the tire.

  Conventionally, steel belts have been used as reinforcing belts for automobile tires. This steel belt is generally a rubber belt in which a plurality of steel cords as reinforcing materials are arranged in parallel so as to extend in the direction along the outer peripheral surface of the tire and obliquely with the tire equatorial plane. It is also common practice to stack two or more steel belt layers so that the oblique directions of the steel cords with respect to the tire equatorial plane are opposite to each other to form a so-called cross belt structure.

  As a material of this steel cord, a high carbon steel wire containing 0.7 to 1.2 wt% of carbon is generally used. Since this high carbon steel wire is a ferromagnetic material, the steel cord may be magnetized during the manufacturing process of the tire or during use of the tire. Tires magnetized with steel cords generate a variable magnetic field due to rotation when the vehicle is running. Therefore, countermeasures are being considered from the viewpoints of the influence on the in-vehicle electronic devices and the environmental viewpoint.

  For example, Patent Documents 1 to 4 listed below disclose methods for reducing the magnetic field generated from a tire by demagnetizing the tire. In particular, Patent Document 1 discloses a device that enables demagnetization of a tire in use while being mounted on a vehicle. Further, in Patent Document 5 below, a plurality of oblique belt layers each configured such that the magnetization direction of the steel cord in the belt layer is a constant direction are set so that the magnetization directions thereof are opposite to each other. A tire in which a magnetic field formed outside is reduced by forming a cross belt structure by laminating the layers is disclosed.

JP 2006-100349 A JP 2005-88817 A JP 2006-82007 A JP 2006-86316 A No. 2004/066512

  As described above, various techniques have been proposed for tire demagnetization. However, even if the steel cord of the belt layer is demagnetized once, it may be magnetized again during the subsequent use of the tire. Therefore, a tire that has a weak magnetic field even when magnetized and is difficult to magnetize during use is desired. In addition, even when demagnetization is performed in a state of being mounted on a vehicle, it is advantageous to apply a tire that generates a weak magnetic field and is not easily magnetized.

  An object of the present invention is to provide an automobile tire in which the above-mentioned problems are solved and the influence of a magnetic field generated due to magnetization of a steel cord used as a reinforcing material for a belt layer is reduced.

  The vehicle tire of the present invention (Claim 1) is a vehicle tire having a steel belt formed by coating a plurality of steel cords with rubber, and at least a part of the rubber member constituting the vehicle tire is high. It is made of rubber containing a magnetic permeability material.

  According to a second aspect of the present invention, there is provided an automobile tire according to the first aspect, wherein at least a part of the rubber constituting the steel belt is made of the high permeability material-containing rubber.

  According to a third aspect of the present invention, there is provided an automobile tire according to the first or second aspect, wherein at least a part of the rubber constituting the tread portion is made of the high permeability material-containing rubber.

  The automobile tire according to claim 4 is the tire according to claim 3, wherein the tread portion is formed by laminating a plurality of rubber sheets, and at least one of the rubber sheets other than the outermost layer in the tire radial direction. Is made of the high magnetic permeability material-containing rubber.

  According to a fifth aspect of the present invention, there is provided an automobile tire according to any one of the first to fourth aspects, wherein at least a part of the rubber constituting the sidewall portion is made of a rubber having a high magnetic permeability material.

  The automobile tire of the present invention (Claim 6) has a high magnetic permeability for shielding magnetism generated from the steel cord in an automobile tire having a steel belt formed by coating a plurality of steel cords with rubber. It has the magnetic shielding layer which consists of a coating-film layer or plating layer containing a material, It is characterized by the above-mentioned.

  The automobile tire according to claim 7 is characterized in that, in claim 6, the magnetic shield layer is present inside the automobile tire.

  An automobile tire according to an eighth aspect is characterized in that, in the seventh aspect, the magnetic shield layer is formed on at least a part of the surface of the steel belt.

  The automobile tire according to claim 9 is characterized in that, in claim 7 or 8, the magnetic shield layer is formed on at least a part of the surface of the rubber member constituting the tread portion.

  The automobile tire according to claim 10 is the tire according to claim 9, wherein the tread portion is formed by laminating a plurality of rubber sheets, and the magnetic shield is formed on a part or all of the surface of the rubber sheet of at least one layer. A layer is formed.

  The automobile tire according to claim 11 is characterized in that, in any one of claims 7 to 10, the magnetic shield layer is formed on at least a part of the surface of the rubber member constituting the sidewall portion. To do.

  The automobile tire according to claim 12 is the tire according to any one of claims 1 to 5, wherein the high magnetic permeability material is contained in the high magnetic permeability material-containing rubber in a direction in which magnetization is difficult. Features.

  According to a thirteenth aspect of the present invention, in the automobile tire according to any one of the first to fifth aspects, the high magnetic permeability material has a flat shape.

  According to a fourteenth aspect of the present invention, in the thirteenth aspect of the present invention, in the thirteenth aspect, the flat-shaped high magnetic permeability material-containing rubber is contained in at least the rubber constituting the sidewall portion.

  The automobile tire according to claim 15 is the tire according to any one of claims 6 to 11, wherein the magnetic shield layer is formed of the coating film layer, and the high-permeability material is aligned with a direction in which magnetization is difficult. It is contained in the layer.

  A tire for an automobile according to a sixteenth aspect is the tire according to any one of the sixth to eleventh aspects, wherein the high magnetic permeability material has a flat shape.

  According to the automobile tire of the present invention (Claim 1), since at least a part of the rubber member constituting the automobile tire is made of a rubber having a high magnetic permeability material, the magnetism directed from the steel cord to the outside of the tire is the high permeability. Shielded by magnetic material containing rubber.

  As described in claim 2, the rubber covering the steel cord of the steel belt may be a rubber having a high magnetic permeability material. In this case, the magnetism from the steel cord toward the outside of the tire is satisfactorily shielded by the high permeability material-containing rubber of the rubber belt that is in the immediate vicinity of the steel cord.

  According to a third aspect of the present invention, at least a part of the rubber constituting the tread portion may be composed of rubber having a high magnetic permeability material. Since the tread portion is located outside the steel cord in the tire radial direction, the magnetism from the steel cord in the tire radial direction is well shielded.

  Further, as in claim 4, the tread portion is formed by laminating a plurality of rubber sheets, and at least one of the rubber sheets other than the outermost layer in the tire radial direction contains a high magnetic permeability material. It may be rubber. In this case, since the rubber sheet made of rubber having a high magnetic permeability material does not wear due to friction with the road surface or the like, the magnetic shielding effect is stably maintained for a long time. In addition, a shielding effect becomes more favorable by setting it as the structure which made the high magnetic permeability material containing rubber sheet several layers, and interpose the non-high magnetic permeability material containing rubber sheet between these.

  According to a fifth aspect of the present invention, at least a part of the rubber constituting the sidewall portion may be a high magnetic permeability material-containing rubber.

  According to the automobile tire of the present invention (Claim 6), since it has a magnetic shield layer made of a coating layer or a plating layer containing a high magnetic permeability material, the magnetism generated from the steel cord is shielded by this magnetic shield layer. The

  According to a seventh aspect of the present invention, it is preferable that the magnetic shield layer is present inside the automobile tire. In this case, since the rubber sheet made of the high magnetic permeability material-containing rubber is not worn by friction with the road surface or the like, the magnetic shielding effect is stably maintained for a long time.

  As in claim 8, a magnetic shield layer may be formed on at least a part of the surface of the steel belt. In this case, the magnetism from the steel cord toward the outside of the tire is well shielded by the magnetic shield layer immediately adjacent to the steel cord.

  As in claim 9, a magnetic shield layer may be formed on at least a part of the surface of the rubber member constituting the tread portion. In this case, since the magnetic shield layer is located outside the steel cord in the tire radial direction, the magnetism from the steel cord toward the tire radial direction is well shielded.

  Further, as in claim 10, the tread portion is formed by laminating a plurality of rubber sheets, and a magnetic shield layer may be formed on a part or all of the surface of at least one rubber sheet. In this case, the shielding effect is further improved by providing a laminated structure in which a plurality of magnetic shield layers and rubber sheets are alternately laminated in the tire radial direction.

  As in the eleventh aspect, a magnetic shield layer may be formed on at least a part of the surface of the rubber member constituting the sidewall portion.

  According to a twelfth aspect of the present invention, the high magnetic permeability material may be contained in the high magnetic permeability material-containing rubber so as to align the direction in which magnetization is difficult. Thereby, the magnetic shielding effect of the high magnetic permeability material can be further improved.

  As in the thirteenth aspect, the high magnetic permeability material may have a flat shape. In this case, the magnetic shielding effect of the high magnetic permeability material can be further improved by orienting the flat high magnetic permeability material. In addition, by setting the direction in which magnetization is difficult to be a flat thickness direction, the density of the high permeability material is improved with respect to the direction in which magnetization is difficult, and the magnetic shielding effect is further improved. In flat high permeability materials, if the direction that is hard to magnetize is the thin direction of the flat shape, aligning the direction that is hard to magnetize into the rubber, and even if it is contained in the rubber, even in the same rubber thickness Many high magnetic permeability materials can be contained, and the magnetic shielding effect of the high magnetic permeability material can be further improved.

  As in the fourteenth aspect, the flat high magnetic permeability material-containing rubber may be contained in at least the rubber constituting the sidewall portion. Since this flat high permeability material also functions as a reinforcing material for the sidewall portion, the magnetic shielding effect is improved and the strength of the sidewall portion is also improved. Here, when a high permeability material is considered as a filler for the rubber of the matrix as a mechanism for improving the strength, the strength increases as the aspect ratio increases. Therefore, the strength is improved by the flat shape.

  According to the fifteenth aspect, the magnetic shield layer may be formed of the coating layer, and the high permeability material may be contained in the coating layer in a direction in which it is difficult to magnetize. Thereby, the magnetic shielding effect of the high magnetic permeability material can be further improved.

  As in the sixteenth aspect, the high magnetic permeability material may have a flat shape. In this case, the magnetic shielding effect of the high magnetic permeability material can be further improved by orienting the flat high magnetic permeability material. In addition, for example, when the tire is molded and the coating film is in a semi-solidified state and proceeds to a vulcanization (post) process, the long side is perpendicular to the direction in which the pressure is applied by the flexibility of the shielding material (the thickness direction of the member) It becomes easy to orient and shield performance improves.

It is sectional drawing of the tire for motor vehicles concerning embodiment. It is drawing explaining the manufacturing method of the tire for motor vehicles of FIG. It is drawing explaining the manufacturing method of the tire for motor vehicles of FIG. It is drawing explaining the manufacturing method of the tire for motor vehicles of FIG. It is drawing explaining the manufacturing method of the tire for motor vehicles of FIG. It is sectional drawing of the steel belt vicinity of the tire for motor vehicles which concerns on different embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a radial cross-sectional view of an automobile tire according to an embodiment, and FIGS. 2 and 3 are cross-sectional views illustrating a green tire forming step in the method of manufacturing an automobile tire of FIG. FIG. 5 is a cross-sectional view for explaining a grooving process in the method for manufacturing an automobile tire shown in FIG. 1, and FIG. 5 is a cross-sectional view for explaining a vulcanization process in the method for manufacturing an automobile tire shown in FIG.

First Embodiment (Embodiments of Claims 1 to 5)]
In the first embodiment, as will be described in detail below, at least a part of the rubber member constituting the automobile tire 1 of FIG. 1 is composed of rubber having a high magnetic permeability material.

  As shown in FIG. 1, an automobile tire 1 includes a pair of bead portions 5 (only one bead portion 5 is shown in FIG. 1) that can be fitted to a rim 3 of a tire wheel. The parts 5 each have a bead core 7 and a bead filler 9 disposed outside the bead core 7 in the tire radial direction R. The bead core 7 is formed by coating a steel wire with rubber.

  One end of a toroidal carcass 11 is connected to the bead core 7 in one bead part 5, and the other end of the carcass 11 is connected to the bead core 7 in the other bead part 5. Both ends of the carcass 11 are connected to each bead core 7 by being folded back from the inside in the tire width direction W so as to wind the bead core 7 around. The carcass 11 is formed by covering a plurality of cords (not shown) extending in the radial direction with rubber.

  A plurality of layers (three layers in FIG. 1) of steel belts 13 are provided on the outer peripheral surface of the crown region of the carcass 11. Each steel belt 13 is formed by covering a plurality of steel cords 15 extending in a direction perpendicular to the tire radial direction R and oblique to the tire circumferential direction C with rubber.

  A tread portion 17 is provided on the outer peripheral surface (upper surface in FIG. 1) of the steel belt 13 as the outermost layer in the tire radial direction R. In the present embodiment, the tread portion 17 includes two layers of an under tread portion 18 on the inner side in the tire radial direction R and a cap tread portion 19 laminated on the outer peripheral surface of the under tread portion 18. A plurality of circumferential main grooves 21 extending in the tire circumferential direction C are formed in the tread portion 17.

  Sidewall portions 23 are respectively provided between the tread portion 17 on one side surface of the carcass 11 and the one bead portion 5 and between the tread portion 17 and the other bead portion 5 on the other side surface of the carcass 11. An inner liner 25 is provided on the inner side surface of the carcass 11 to prevent air leakage.

  In the present embodiment, at least a part of the rubber member that constitutes the automobile tire 1 is made of high permeability material-containing rubber. For example, the rubber covering the steel cord 15 of the steel belt 13, the under tread portion 18, the cap tread portion 19, the sidewall portion 23, the rubber covering the cord of the carcass 11, the bead filler 9, and the steel wire of the bead core 7. At least one part of the rubber | gum which coat | covers, and the inner liner 25 is comprised with the high magnetic permeability material containing rubber | gum.

  In particular, it is preferable that at least one part of the rubber covering the steel cord, the under tread part 18 and the cap tread part 19 of the steel belt 15 is made of a high magnetic permeability material-containing rubber. Since these rubber members are located outside the steel cord 15 in the tire radial direction R, the magnetism from the steel cord 15 toward the outside in the tire radial direction R is shielded. For this reason, it is possible to satisfactorily prevent the magnetism from leaking into the vehicle-mounted electronic device or the vehicle interior.

  In particular, it is preferable that at least one part of the rubber covering the steel cord and the under tread part 18 of the steel belt 15 is made of a high magnetic permeability material-containing rubber. Since these rubber members are present inside the automobile tire 1, they are not worn due to friction with the road surface during use, and the magnetic shielding effect is stably maintained over a long period of time.

  In addition, the whole rubber member may be made of a high magnetic permeability material-containing rubber, or a part thereof may be made of a high magnetic permeability material-containing rubber. For example, when the cap tread portion 19 is made of a high magnetic permeability material-containing rubber, the inner side in the tire radial direction R is preferably made of a high magnetic permeability material-containing rubber. In this case, the high magnetic permeability material-containing rubber is not worn due to friction with the road surface, etc., so that the magnetic shielding effect is maintained.

  The high magnetic permeability material of the high magnetic permeability material-containing rubber includes oxides such as Mn—Zn ferrite, Ni—Zn ferrite, Cu—Zn ferrite, iron, cobalt, nickel, or any or all of these. Amorphous alloy containing, silicon steel such as flat silicon iron (Fe-4Si), supermalloy (Fe-79Ni-5Mo), 78 permalloy (Fe78-78.5Ni), 45 permalloy (Fe45Ni), hard palm (Fe- 79Ni-9Nb), mumetal (Fe-77Ni-2Cr-5Cu) and other metals such as permalloy, alpalm (Fe-16Al), permendur (Fe-50Co), flat sendust (Fe-5Al-10Si) Preferably used.

  The content of the high magnetic permeability material is, for example, 400 to 800 parts by mass, particularly 500 to 700 parts by mass, especially 600 to 650 parts by mass with respect to 100 parts by mass of rubber. If it is less than 400 parts by mass, there is a problem in terms of the magnetic shielding effect, and if it exceeds 800 parts by mass, there is a problem in terms of workability with rubber.

  As a form of this high magnetic permeability material, a fine powder form and a flake form are preferable in terms of workability with rubber.

  When the high magnetic permeability material is spherical, the particle diameter is preferably from 0.1 to 50 μm, particularly preferably from 0.5 to 20 μm, particularly preferably from 1 to 10 μm. If the particle size is too large, there is a problem in terms of mechanical strength of the rubber, and if it is too small, there is a problem in terms of processability with rubber.

  When the high magnetic permeability material is flat, the average particle size is preferably 0.1 μm to 20 μm, particularly preferably 0.5 to 10 μm, the thickness is preferably 0.1 to 5 μm, particularly preferably 0.2 to 1 μm, and the aspect ratio is 1 to 1. 10 2 to 5 are particularly preferable. If the average particle size is too large, there is a problem in terms of the mechanical strength of the rubber, and if it is too small, there is a problem in terms of processability with the rubber. When the thickness is too large, the aspect ratio becomes small, and thus there is a problem that the magnetic shielding properties are lowered along with the orientation. In addition, when the thickness is too small, there is a problem that the material is destroyed during strong shearing such as kneading and the shape cannot be maintained. When the aspect ratio is 2 or more, the magnetic shielding effect is improved. When the aspect ratio is 2 or less, since the magnetic anisotropy is not sufficient, the shielding effect is small.

  In addition, an average particle diameter and average thickness are based on the particle size distribution measurement and electron microscope observation of a wet method.

  This high magnetic permeability material can be produced, for example, by an atomizing method such as a water atomizing method or a gas atomizing method, whereby a high magnetic permeability material of a granular powder with uniform particle size can be obtained. Further, by flattening the granular powder with an attritor, ball mill, stamp mill or the like, a flat high magnetic permeability material can be obtained.

  In order to contain this high magnetic permeability material so as to be oriented in the high magnetic permeability material-containing rubber, it may be solidified under pressure while the rubber is softened at a high temperature of 150 ° C. or higher. Usually, this operation is performed in a rubber vulcanization process or the like.

  When the sidewall portion 23 is a high permeability material-containing rubber containing the flat shape high permeability material, the flat shape high permeability material functions as a reinforcing member. And the strength of the sidewall portion 23 is improved.

  In the high magnetic permeability material-containing rubber, the magnetic shielding effect is further improved by arranging the high magnetic permeability material in the rubber in the same direction in which it is difficult to magnetize. As described above, as described above, a flat high magnetic permeability material may be oriented in the high magnetic permeability material-containing rubber. In addition, it is also possible to use a method in which magnets are arranged so that the lines of magnetic force are aligned perpendicular to the direction in which pressure is applied and solidified in a magnetic field oriented state.

  Next, an example of a method for manufacturing the automobile tire 1 shown in FIG. 1 will be described.

  The manufacturing method of the automobile tire 1 includes a green tire molding process, a grooving process, and a vulcanization process. Details of each step are as follows.

<Green tire molding process>
As shown in FIG. 2, the green tire 1u is molded using a cylindrical molding drum 27 whose central portion can be expanded and contracted in the drum radial direction.

  First, an unvulcanized inner liner 25u is stuck on the outer peripheral surface of the molding drum 27, and an unvulcanized carcass 11u is stuck on the unvulcanized inner liner 25u.

  Next, an unvulcanized bead core 7u and an unvulcanized bead filler 9u are set in the vicinity of one end of the unvulcanized carcass 11u, and the vicinity of one end of the carcass 11u is folded back so as to enclose them. One bead portion 5u of sulfur is formed. Similarly, by setting an unvulcanized bead core 7u and an unvulcanized bead filler 9u in the vicinity of the other end of the unvulcanized carcass 11u, and folding back the vicinity of the other end of the carcass 11u so as to entrain them. The other uncured bead portion 5u is formed.

  Further, unvulcanized sidewalls (unvulcanized sidewall rubber) 23u are attached to positions adjacent to the respective bead portions 5u in the unvulcanized carcass 11u. Thereafter, as shown in FIG. 3, the central portion of the molding drum 27 is expanded and moved in the drum radial direction to form an unvulcanized carcass 11u in a toroid shape, and a green case is molded. FIG. 2 shows a state before the central portion of the molding drum 27 is expanded and moved in the drum radial direction, and FIG. 3 shows a state after the central portion of the molding drum 27 is expanded and moved in the drum radial direction. Shows the state.

  After the green case is molded, the unvulcanized steel belt 13u is pasted around the crown region of the unvulcanized carcass 11u so as to be wound in a plurality of layers (three layers in this embodiment). Next, an unvulcanized tread portion 17u is formed by laminating and winding an unvulcanized undertread rubber sheet 18u and a cap tread rubber sheet 19u on an unvulcanized belt 13u. In this way, the green tire 1u is molded.

  In the present embodiment, at least a part of the unvulcanized rubber member is a high permeability material-containing rubber. For example, at least one of the unvulcanized sidewall 23u, the unvulcanized steel belt 13u, the unvulcanized undertread rubber sheet 18u, and the unvulcanized cap tread rubber sheet 19u is made of a high magnetic permeability material. .

<Grooving process>
After the green tire molding process is completed, the molding drum 27 in a state where the green tire 1u is pasted is used as a known grooving device (grooving device) described in, for example, JP-A-8-80582 and JP-A-4-68137. Is set to (not shown).

  Then, as shown in FIG. 4, an unvulcanized tread is formed by cutting the outer circumferential surface of the unvulcanized tread portion 17u with the cutter 29 of the grooving device and rotating the green tire 1u in the tire circumferential direction C. A primary circumferential main groove 21u extending in the tire circumferential direction C is formed on the outer circumferential surface of the portion 17u. Further, by changing the position of the cutter 29 in the tire width direction W and repeating the same operation, a plurality of primary circumferential main grooves 21u are formed in the unvulcanized tread portion 17u.

<Vulcanization process>
After the grooving process is completed, the green tire 1u is vulcanized using the vulcanization mold 33.

  As shown in FIG. 5, a plurality of annular groove forming protrusions 31 are provided on the inner surface. The green tire 1u is set in the vulcanization mold 33 so that each primary circumferential main groove 21u engages with the corresponding groove forming protrusion 31.

  The detailed configuration of the vulcanization mold 33 is as follows.

  Here, the vulcanization mold 33 includes an annular plate-shaped lower mold 35 and an upper mold 37 that are arranged facing each other vertically, and a peripheral wall-shaped sector mold 39 that is disposed between these outer peripheral portions. Yes. The lower mold 35 is installed on a fixed frame (not shown) in the vulcanizer. The upper mold 35 mainly molds one sidewall portion 23 and one bead portion 5. The upper mold 37 is installed on an elevating frame (not shown) that can be raised and lowered in the vulcanizer. The upper mold 37 mainly molds the other sidewall portion 23 and the other bead portion 5. The sector mold 39 is provided on the lower mold 35. The sector mold 39 mainly molds the tread portion 17. The sector mold 39 is segmented so as to be able to expand and contract in the radial direction of the mold, and the plurality of groove forming protrusions 31 described above are formed on the inner surface of the sector mold 39.

  After setting the green tire 1u in the vulcanizing mold 33, the green tire 1u is vulcanized while being pressurized from the inside by the bladder 41, whereby the automobile tire 1 is molded.

[Second Embodiment (Embodiments of Claims 6 to 11)]
In the first embodiment, at least a part of the rubber member constituting the automobile tire 1 is made of rubber having a high magnetic permeability material, but instead of or together with this, a high You may provide the magnetic shielding layer which consists of a coating-film layer or a plating layer containing a magnetic permeability material.

  For example, as shown in FIG. 6, a magnetic shield layer 40 made of a coating layer or a plating layer containing a high magnetic permeability material may be provided on the surface of the steel belt 13.

  In order to manufacture the automobile tire having the magnetic shield layer 40, in the method for manufacturing the automobile tire 1 shown in FIG. 1, as the unvulcanized steel belt 13u, a magnetic shield composed of a coating layer or a plating layer on the surface. What provided the layer 40 should just be used.

  When the magnetic shield layer 40 is formed of a coating layer, for example, a paint in which a powder made of a high magnetic permeability material is dispersed in a binder base material made of a resin such as polyurethane is used as an unvulcanized steel belt 13u. What is necessary is just to apply | coat to the surface of.

  The concentration of the high magnetic permeability material in the paint is preferably 40 to 80% by mass, particularly 55 to 70% by mass. If it is less than 40% by mass, there is a problem in terms of the magnetic shielding effect, and if it exceeds 70% by mass, there are problems in terms of the coating property of the paint and the strength / durability of the material.

  The dimensions, manufacturing method, and flattening method of the high magnetic permeability material are the same as those in the first embodiment.

  When the high-permeability material in the paint has a flat shape, the flat high-permeability material is oriented so that the thickness direction is the film thickness direction of the coating layer in the drying process after application of the paint. To do.

  In this coating layer, the magnetic shielding effect of the coating layer is further improved by aligning the direction of difficulty in magnetization of the high permeability material into the coating layer. As the method, as described above, a flat high magnetic permeability material is oriented in the coating layer.

  When the magnetic shield layer 40 is composed of a plating layer, for example, the surface of the unvulcanized steel belt 13u is plated by a low-temperature plating method as disclosed in JP-A-2007-123598. Can be applied.

  In the above embodiment, the magnetic shield layer 40 is provided on the entire surface of the steel belt 13, that is, the upper surface, the lower surface and the side surface in FIG. 4. However, the magnetic shield layer 40 is provided on a part of the surface of the steel belt 13. It may be provided. For example, the magnetic shield layer 40 may be provided on the top and side surfaces of the steel belt 13.

  Further, a magnetic shield layer may be provided at a location other than the surface of the steel belt 13 in the automobile tire. For example, a magnetic shield layer may be provided on the inner peripheral surface and outer peripheral surface of the under tread portion 18 in FIG. 1, the inner peripheral surface of the cap tread portion 19, the inside of the sidewall portion 23, and the like.

  The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment.

  For example, in FIG. 1, the tread portion 17 has a two-layer structure of an undertread portion 18 and a cap tread portion 19. An intermediate tread portion (not shown) is provided between the undertread portion 18 and the cap tread portion 19. ) May be provided in one or more layers. In this case, at least one layer of the intermediate tread portion may be a rubber having a high magnetic permeability material, and a magnetic shield layer comprising a coating layer or a plating layer containing the high magnetic permeability material on the surface of at least one layer of the intermediate tread portion. May be provided. Further, the tread portion 17 may have a single layer structure.

  In the automobile tire 1 of FIG. 1, cushion rubber may be provided on both sides of the steel belt 13 in the tire width direction W. In order to provide the cushion rubber, first, an unvulcanized carcass 11u is connected so as to be connected to an end portion on the center side in the tire width direction (left and right direction in the drawing) of the left unvulcanized sidewall 23u in FIG. An unvulcanized left cushion rubber is provided on the top. Similarly, an unvulcanized right cushion rubber is provided on the unvulcanized carcass 11u so as to be connected to the central end portion in the tire width direction of the right unvulcanized sidewall 23u in FIG. The unvulcanized steel belt 13u is wound between these unvulcanized cushion rubbers. Thereafter, an automobile tire may be molded as described with reference to FIGS. The cushion rubber may be a rubber having a high magnetic permeability material, and a magnetic shield layer made of a coating layer or a plating layer containing the high magnetic permeability material may be provided on at least a part of the surface of the cushion rubber. .

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

[Examples 1 to 5 and Comparative Examples 1 and 2]
<Preparation of sample>
A rubber sheet (length 150 mm × width 100 mm × thickness 2 mm) was obtained by kneading and mixing high permeability powder with natural rubber as shown in Table 1 and press molding.

  The details of the high permeability powder in Table 1 are as follows.

Mn—Zn ferrite powder: BSF-547 manufactured by Toda Kogyo Co., Ltd., average particle diameter of 3.2 μm
High silicon steel powder: Sanyo Special Steel Co., Ltd. Fe-50Ni, powder average particle size 4.5 μm
Sendust powder: Sanyo Special Steel PST4-FM60, average particle size 7.6 μm
78 Permalloy powder: Average particle size 8.5 μm
Flat 78 permalloy powder: manufactured by Pacific Sowa, PC-78,
Average particle size 5.2 μm, average aspect ratio 2.7

  The average particle size of the powder was measured using a laser dispersion type particle size distribution analyzer. The average thickness was measured by using a SEM by embedding the powder in a resin while the powder was oriented in the flat direction by a magnet, polishing the cross section. The average aspect ratio was calculated as the ratio of the average particle diameter to the average thickness (average particle diameter / average thickness). The flat 78 permalloy powder is obtained by subjecting a granular powder produced by a water atomizing method to a flattening process by collision pulverization by a jet mill process.

  Further, a steel belt member (length 400 mm × width 80 mm × thickness 2 mm) obtained by coating a plurality of steel cords arranged in parallel with natural rubber was manufactured. As a material of the steel cord, a high carbon steel wire containing 0.8 wt% carbon was used.

  This steel belt member was magnetized as follows.

  As a magnet for magnetizing the steel belt member, a ferrite magnet having a length of 200 mm, a width of 30 mm, a thickness of 5 mm, and a residual magnetic flux density of 2000 gauss magnetized in the thickness direction was used. The length direction of the magnet is perpendicular to the cord driving direction of the steel belt member, and the width direction of the magnet is parallel to the cord driving direction of the steel belt member, and the magnet is held in contact with the central portion of the steel belt member for 10 seconds. After that, the magnet was magnetized so as to be away from the steel belt member.

  Three rubber sheets were placed side by side in a row on the upper surface of the steel belt member magnetized in this manner, covering the entire upper surface of the steel belt member. A sample was thus obtained.

<Measurement of magnetic field>
The magnetic field distribution over the entire surface of the sample (the surface on the side where the rubber sheet is disposed) was measured. As a measuring instrument, a 421 type transparse probe manufactured by Lakeshore was used. Based on the measurement result of the magnetic field distribution, the average value and the fluctuation range of the magnetic field distribution (difference between the maximum value and the minimum value in the magnetic field distribution) were calculated. This average value was indicated by an index with the average value of Comparative Example 1 as 100. In addition, this variation value is indicated by an index with the variation range of Comparative Example 1 as 100. The results are shown in Table 1.

  As apparent from Table 1, it was confirmed that by covering the upper surface of the steel belt member with a rubber sheet made of high permeability material-containing rubber, the magnetism was well shielded and the generated magnetic field of the tire steel belt could be suppressed.

  Further, as apparent from the comparison between Example 3 and Example 4, when the content of the high magnetic permeability material is the same amount, the magnetic shielding effect is better when the shape of the high magnetic permeability material is flat. Was confirmed to be high.

[Examples 6 to 10 and Comparative Examples 3 and 4]
<Preparation of sample>
The tire size 185 having the structure shown in FIGS. 1 to 5 is formed by using the high permeability material-containing rubber shown in Table 2 for the members shown in Table 2 and using natural rubber for the other tire members. A / 70R14 pneumatic radial tire was produced. The details of the high magnetic permeability powder in Table 2 are the same as in Examples 1 to 3 and Comparative Examples 1 and 2.

  Before producing this pneumatic radial tire, the unvulcanized steel belt 13u was magnetized by the following procedure.

  As a magnet for magnetizing the unvulcanized steel belt 13u, a ferrite magnet having a length of 200 mm, a width of 30 mm, a thickness of 5 mm and a residual magnetic flux density of 2000 gauss magnetized in the thickness direction was used. The length direction of the magnet is perpendicular to the cord driving direction of the steel belt member, the width direction of the magnet is parallel to the cord driving direction of the unvulcanized steel belt 13u, and the magnet is brought into close contact with the central portion of the belt 13u. After being held for 2 seconds, the magnet was magnetized so as to move away from the belt 13u.

  The steel belt 13 has a so-called cross belt structure.

<Measurement of magnetic field>
The magnetic field distribution over the entire surface of the sample (the surface on the side where the rubber sheet is disposed) was measured. As a measuring instrument, a 421 type transparse probe manufactured by Lakeshore was used. Based on the measurement result of the magnetic field distribution, the average value and the fluctuation range of the magnetic field distribution (difference between the maximum value and the minimum value in the magnetic field distribution) were calculated. This average value is indicated by an index with the average value of Comparative Example 3 as 100. In addition, this variation value is indicated by an index with the variation range of Comparative Example 3 as 100. The results are shown in Table 2.

  As is clear from Table 2, the magnetism from the steel belt 13 is well shielded by covering the lowermost part of the tire undertread part 18 or the upper part of the sidewall part 23 with a rubber sheet made of rubber having a high magnetic permeability material. It was confirmed that the magnetic field generated by the steel belt could be suppressed.

  Further, as is clear from the comparison between Example 8 and Example 12, when the content of the high magnetic permeability material is the same, the magnetic shielding effect is better when the shape of the high magnetic permeability material is flat. Was confirmed to be high.

DESCRIPTION OF SYMBOLS 1 Car tire 11 Carcass 13 Steel belt 15 Steel cord 17 Tread part 18 Under tread part 19 Cap tread part 40 Magnetic shield layer

Claims (16)

In an automobile tire having a steel belt formed by coating a plurality of steel cords with rubber,
An automobile tire characterized in that at least a part of a rubber member constituting the automobile tire is made of a rubber having a high magnetic permeability material.   2. The automobile tire according to claim 1, wherein at least a part of rubber constituting the steel belt is made of the high permeability material-containing rubber.   3. The automobile tire according to claim 1, wherein at least a part of the rubber constituting the tread portion is made of the high permeability material-containing rubber. In Claim 3, the tread portion is formed by laminating a plurality of rubber sheets,
Of the rubber sheet, at least one of the layers other than the outermost layer in the tire radial direction is made of the high magnetic permeability material-containing rubber.   5. The automobile tire according to claim 1, wherein at least a part of the rubber constituting the sidewall portion is made of a rubber having a high magnetic permeability material. In an automobile tire having a steel belt formed by coating a plurality of steel cords with rubber,
An automobile tire comprising a magnetic shield layer made of a coating layer or a plating layer containing a high magnetic permeability material for shielding magnetism generated from the steel cord.   The automobile tire according to claim 6, wherein the magnetic shield layer is present inside the automobile tire.   8. The automobile tire according to claim 7, wherein the magnetic shield layer is formed on at least a part of the surface of the steel belt.   9. The automobile tire according to claim 7 or 8, wherein the magnetic shield layer is formed on at least a part of the surface of the rubber member constituting the tread portion. In Claim 9, the tread portion is formed by laminating a plurality of rubber sheets,
An automobile tire characterized in that the magnetic shield layer is formed on a part or all of the surface of at least one rubber sheet.   11. The automobile tire according to claim 7, wherein the magnetic shield layer is formed on at least a part of a surface of a rubber member constituting the sidewall portion.   6. The automobile tire according to claim 1, wherein the high magnetic permeability material is contained in the high magnetic permeability material-containing rubber in a direction in which magnetization is difficult.   The automobile tire according to any one of claims 1 to 5, wherein the high magnetic permeability material has a flat shape.   14. The automobile tire according to claim 13, wherein the flat-shaped high-permeability material-containing rubber is contained in at least rubber constituting the sidewall portion. In any one of Claims 6 thru | or 11, the said magnetic shield layer consists of the said coating-film layer,
The automobile tire, wherein the high magnetic permeability material is contained in the coating layer in a direction in which it is difficult to magnetize.   The automobile tire according to any one of claims 6 to 11, wherein the high magnetic permeability material has a flat shape.

Images