Tire

Abstract

To provide a tire in which a density of a black color can be increased more than before to enhance contrast and which is excellent in formability.SOLUTION: In a tire 1, a pattern region 7 is formed visibly, as a site that is different from a circumference of at least a portion of an outer surface of a side wall 3, on the portion. A plurality of protrusions 110 protruding from a reference surface 7a are formed on the pattern region 7. The protrusion 110 has a recessed part 111 having a mortar-shaped inner surface, a cone-shaped trunk part 112 forming an outer periphery of the protrusion 110 and extending in a cone shape in a protruding direction of the protrusion 110 from the reference surface 7a, and an outer edge part 113 surrounding the circumference of the recessed part 111. A protruding height of the protrusion 110 is 0.6 mm or more and 1.4 mm or less, and a depth of the recessed part 111 is 30% or more and 70% or less of the protruding height of the protrusion 110.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a tire having a pattern area on at least a portion of the outer surface of the sidewall for displaying, for example, an insignia or a design. [Background technology]

[0002] Conventionally, tires have been known that have a pattern area in which a large number of minute protrusions are arranged in a portion of the tire sidewall (for example, Patent Document 1, etc.). Such pattern areas absorb light by repeatedly reflecting incident light between the protrusions, which makes the area appear darker than the surrounding outer surface of the sidewall, improving contrast. By providing this type of pattern area, the tire can be improved in terms of design effect and appearance, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-131904 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the tire disclosed in Patent Document 1, the minute protrusions are arranged in a lattice-shaped portion surrounded by rib-shaped protrusions, which makes the structure complex and difficult to manufacture, and therefore there is a risk that the desired shape may not be obtained, which may result in a poor appearance.

[0005] An object of the present disclosure is to provide a tire that has a higher black density than conventional tires, thereby achieving high contrast, and that has good moldability. [Means for solving the problem]

[0006] The pneumatic tire disclosed herein is a tire having a pattern area on at least a portion of the outer surface of a sidewall, which is visibly different from the surrounding area of ​​the portion, and the pattern area has a plurality of protrusions protruding from a reference surface, each of which has a recess with a cone-shaped inner surface, a cone-shaped body that forms the outer periphery of the protrusion and extends in a cone-like shape from the reference surface in the direction in which the protrusion protrudes, and an outer edge that surrounds the recess, and the protrusion height of the protrusion is 0.6 mm or more and 1.4 mm or less, and the depth of the recess is 30% or more and 70% or less of the protrusion height of the protrusion. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a tire that has a higher black density than conventional tires, thereby achieving high contrast, and that has good moldability. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view of a tire 1 according to a first embodiment. [Figure 2] 1 shows an example of a tire molding die for vulcanizing and molding a tire 1 according to an embodiment. [Figure 3] FIG. 2 is a perspective view showing a plurality of protrusions 110 arranged in a pattern region 7. [Figure 4] 4 is a plan view showing a plurality of protrusions 110 arranged in the pattern region 7, taken along the arrow T in FIG. 3. FIG. [Figure 5] 5 is a cross-sectional view of a plurality of protrusions 110 arranged in the pattern region 7 taken along the position of the arrow AA in FIG. 4. FIG. [Figure 6] FIG. 10 is a cross-sectional view showing an example in which the outer edge portion 113 is configured as a flat surface. [Figure 7] 10 is a table summarizing the experimental results. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a side view of a tire 1 according to a first embodiment. The tire 1 is a so-called pneumatic tire whose inner cavity is filled with a predetermined air pressure. The tire 1 of the embodiment is a pneumatic tire for passenger cars including light cars and SUVs. Note that the configuration of the tire 1 of the embodiment can also be applied to pneumatic tires for other vehicle types, such as light trucks, trucks, and buses.

[0011] First, an overview of the configuration of the tire 1, mainly related to its side surface, will be described with reference to FIG. 1. FIG. 1 is a side view of the tire 1 as viewed from the direction of the tire rotational axis X. In the following description, the tire axial direction, tire circumferential direction, and tire radial direction are as follows: The tire axial direction is the direction in which the tire rotational axis X extends, and in FIG. 1 refers to the front-to-back direction of the page. When viewed from the tire radial direction, the tire axial direction is the left-to-right direction, and therefore may also be referred to as the left-to-right direction. The tire circumferential direction is an arc line centered on the tire rotational axis X, and is the direction along the rotational direction of the tire 1, and is indicated by arrow G in FIG. 1. The tire radial direction is the direction perpendicular to the tire rotational axis X, and is arbitrarily indicated by arrow Y in FIG. 1.

[0012] As shown in Fig. 1, the tire 1 includes a bead 2, a sidewall 3 extending radially outward from the bead 2 away from the tire rotational axis X in the tire radial direction, and a tread 4. Each of the bead 2 and the sidewall 3 is provided on one side of the tire 1 shown in Fig. 1 on one side of the tire 1, and on the other side of the tire 1 not shown in Fig. 1 away from the tire axial direction, i.e., a pair of left and right bead 2 and sidewall 3. The tread 4 is disposed between the left and right sidewalls 3 on the outer sides in the tire radial direction. The outer peripheral surface of the tread 4 includes a tread surface that comes into contact with the road surface.

[0013] The tire 1 is mainly composed of multiple types of rubber that form the beads 2, sidewalls 3, and tread 4. A carcass ply that forms the framework of the tire 1 is disposed on the inner cavity side of the rubber that forms the entire tire 1, and an inner liner that maintains air pressure is disposed on the inner cavity side of the carcass ply. An annular reinforcing belt is embedded inside the rubber that forms the tread 4 (the carcass ply, inner liner, and reinforcing belt are not shown). In addition to these components, various other components may be provided as necessary for the function of the tire 1.

[0014] As shown in Fig. 1, the sidewall 3 has an annular decorative area 5 on its outer surface 3a, spanning the entire circumference in the tire circumferential direction. The decorative area 5 is an area of ​​a constant width sandwiched between an inner arc line 5a on the inner side in the tire radial direction and close to the tire rotation axis X, and an outer arc line 5b on the outer side in the tire radial direction than the inner arc line 5a. The inner arc line 5a and the outer arc line 5b may be lines formed by concavities, convexities, or steps on the outer surface 3a of the sidewall 3, or may be imaginary lines that do not actually exist.

[0015] The decorative area 5 on the outer surface 3a of the sidewall 3 may be located radially outward of the maximum tire width position or may be located at a position that includes the maximum tire width position. The maximum tire width position refers to the position between the outer surfaces 3a of the left and right sidewalls 3 that has the longest axial length.

[0016] The tire 1 has a pattern area 7 provided in a part of the outer surface 3a of the sidewall 3 in a state where it is visibly different from the surrounding area of ​​the part. The pattern area 7 is provided in the sidewall rubber, which is a black rubber member that forms the outer surface of the sidewall 3.

[0017] As shown in FIG. 1 , the annular decorative region 5 is provided with marking portions 6A at two opposing locations across the tire rotation axis X. The marking portions 6A are formed by a plurality of characters arranged in the tire circumferential direction. These characters indicate at least one mark such as the manufacturer's name, product name, or brand. Each character may be formed with a concave or convex border, or the entire character may be formed in a concave or convex shape. For example, each character in the marking portion 6A is provided as a pattern region 7 of the embodiment.

[0018] 1, pattern portions 6B are provided in two locations in the annular decorative area 5, sandwiched between two emblem portions 6A in the circumferential direction. The pattern portions 6B are provided with a pattern that resembles a parallelogram curved to imitate the annular decorative area 5. For example, each pattern in the pattern portions 6B is also provided as a pattern area 7 of the embodiment.

[0019] The shape of the pattern area 7 is not limited to these, and may be any shape, or a shape depicting marks such as the manufacturer name, product name, brand, etc. mentioned above, or a shape depicting other numbers, letters, etc., etc.

[0020] Each of the pattern regions 7 in the embodiment has a reference surface 7a that follows the profile of the sidewall 3. A plurality of protrusions 110, which will be described later, are formed on this reference surface 7a. The pattern region 7 is an area that is provided in a state where it can be visually recognized as a part that is different from the surrounding area of ​​the pattern region 7 by forming a plurality of protrusions 110. Note that the reference surface 7a may protrude axially outward from the profile of the sidewall 3, may be recessed axially inward from the profile of the sidewall 3, or may be a surface that is in the same position as the profile of the sidewall 3 in the tire axial direction.

[0021] Fig. 2 shows an example of a tire molding mold for vulcanizing and molding the tire 1 of the embodiment. Fig. 2 is a meridian cross-sectional view of such a tire molding mold 10 taken along the axial direction of the tire 1 to be molded.

[0022] The tire mold 10 shown in FIG. 2 includes a plurality of sectors 11 arranged circumferentially along the outer periphery of the tire 1, a pair of side plates 12 arranged on both axial sides of an annular body formed by combining the plurality of sectors 11, and a pair of bead rings (not shown). During vulcanization molding, an unvulcanized tire 1a that will become the tire 1 is set inside the tire mold 10, as indicated by the dashed line in FIG. 2. The combination of the sectors 11, the side plates 12, and the bead rings forms a mold for molding the tire 1, and the outer surface of the entire tire 1 is formed by the inner surfaces of the mold, i.e., the inner surfaces 11a of the sectors 11, the inner surfaces 12a of the side plates 12, and the inner surfaces of the bead rings. During vulcanization molding, a bladder (not shown) is placed inside the unvulcanized tire 1a to press the unvulcanized tire 1a against the inner surface of the tire mold 10. The tread 4 is mainly formed by the plurality of sectors 11, and the sidewalls 3 are mainly formed by the pair of side plates 12. The bead 2 is formed by the pair of bead rings, and the entire inner surface of the tire 1 is formed by the bladder.

[0023] The tire molding mold 10 vulcanizes the unvulcanized tire 1a to form the rubber shape of the entire tire 1, and also forms a plurality of protrusions 110, which will be described next, in the pattern region 7 described above.

[0024] FIG. 3 is a perspective view showing multiple protrusions 110 arranged in the pattern region 7. FIG. 4 is a plan view showing multiple protrusions 110 arranged in the pattern region 7, taken along the arrow T in FIG. 3. FIG. 5 is a cross-sectional view of the multiple protrusions 110 arranged in the pattern region 7, taken along the arrow AA in FIG. 4. The multiple protrusions 110 are arranged to protrude from the reference surface 7a of the pattern region 7, but FIGS. 3 to 5 show the multiple protrusions 110 protruding from a UV development reference surface 7b obtained by UV development of the reference surface 7a of the pattern region 7. FIG. 5 also shows a cross section of only one protrusion 110. The UV development reference surface 7b is a surface obtained by two-dimensionally developing the outer surface 3a of the three-dimensional sidewall 3.

[0025] A plurality of protrusions 110 are arranged so as to protrude from the reference surface 7a substantially axially outward of the tire. In this embodiment, the protrusions 110 are arranged regularly in a plurality of rows as shown in FIG. 4. Specifically, in one row, the protrusions 110 are arranged closely and at equal intervals (equal pitch), and adjacent rows are arranged in a close-packed arrangement with the relative positions of the protrusions 110 shifted by half a pitch. Note that the arrangement of the protrusions 110 is not limited to a close-packed arrangement, and may be arranged, for example, at a predetermined interval without being closely spaced, or may be arranged randomly within a range that maintains a predetermined arrangement density. The protrusion 110 has a recess 111, a conical body portion 112, and an outer edge portion 113.

[0026] The recess 111 is located at the center of the protrusion 110 when the protrusion 110 is viewed from above (the direction of the arrow T in FIG. 3), and has a mortar-shaped (conical) inner surface. The bottom of the recess 111 is formed into a minute curved surface that is formed into a substantially hemispherical inner surface shape.

[0027] The conical body 112 forms the outer periphery of the protrusion 110. The conical body 112 extends in a conical shape from the reference plane 7a in the direction in which the protrusion 110 protrudes. Here, "conical" refers to a shape that diverges toward the end, such as a conical surface. Furthermore, in the cross-sectional shape shown in FIG. 5 , which is perpendicular to the reference plane 7a, the inclined surface of the conical body 112 and the inclined surface of the recess 111 are preferably symmetrical, and this is also the case for the protrusion 110 of this embodiment. Here, the symmetry between the inclined surface of the conical body 112 and the inclined surface of the recess 111 means that they are in an axisymmetric relationship in the cross-sectional shape shown in FIG. 5 . Therefore, if the angle between the inclined surface of the conical body 112 and the reference plane 7a is θ and the angle between the inclined surface of the recess 111 and the reference plane 7a is α, then the relationship θ = α is satisfied. By achieving this relationship, the angle of reflection of light at the conical body 112 and the angle of reflection of light at the recess 111 become approximately the same, making it easy to perform optical design including light absorption and making the light absorption effect uniform.

[0028] The outer edge 113 surrounds the recess 111 and forms the tip of the protrusion 110. In the example shown in Fig. 5, the outer edge 113 is formed in a curved shape that smoothly connects the recess 111 and the conical body 112. For example, in the cross section shown in Fig. 5, the outer edge 113 can be configured to smoothly connect the recess 111 and the conical body 112 with a radius of curvature R of approximately 0.01 mm.

[0029] Furthermore, the outer edge portion 113 is not limited to a curved shape and may be configured as a flat surface. Fig. 6 is a cross-sectional view showing an example in which the outer edge portion 113 is configured as a flat surface. For example, the outer edge portion 113 may be configured as a flat surface parallel to the reference plane 7a as shown in Fig. 6.

[0030] A portion of the light that reaches the recess 111 of the protrusion 110 is reflected by the inclined surface of the recess 111, and the reflected light is further reflected repeatedly inside the recess 111. As this repetition of light reflection occurs within the recess 111, the light that reaches the recess 111 is gradually attenuated and absorbed. Furthermore, a portion of the light that reaches the conical body 112 of the protrusion 110 is reflected by the inclined surface of the conical body 112, and a portion of the reflected light reaches and is reflected by the conical body 112 of another nearby protrusion 110, repeating this process. As this repetition of light reflection occurs at the conical body 112 of multiple protrusions 110, the light that reaches the conical body 112 is gradually attenuated and absorbed. Therefore, since a portion of the light incident on the pattern region 7 having a plurality of protrusions 110 is absorbed and does not exit to the outside, when the pattern region 7 having a plurality of protrusions 110 is visually observed, the pattern region 7 appears darker than the outer surface 3a of the sidewall 3, which reflects the light around the pattern region 7.

[0031] Here, the light absorption effect varies depending on the dimensions of each part of the protrusion 110. In addition to the light absorption effect, stable manufacturing in the manufacturing process is also required. Because the shape of the protrusion 110 is a repetition of fine shapes, there is a risk that the shape cannot be stably formed into the desired shape. Therefore, multiple test pieces with different shapes and dimensions of each part of the protrusion 110 were produced, and experiments were conducted to verify the light absorption and molding accuracy.

[0032] FIG. 7 is a table summarizing the experimental results. As shown in FIGS. 5 to 7, the maximum outer diameter of the protrusion 110 is D1, the maximum inner diameter of the recess 111 is D2, the height of the protrusion 110 from the reference plane 7a is H1, and the depth of the recess 111 is H2. Also, the angle formed by the slope of the conical body 112 and the reference plane 7a in the cross section shown in FIGS. 5 and 6 is θ. In the experiment, Examples 1 to 3 and a comparative example were prepared, and actual test pieces were fabricated and compared. The design values ​​and measured values ​​of each test piece are shown in FIG. 7. Also, in FIG. 7, the ratio (H2 / H1) of the depth H2 of the recess 111 to the height H1 of the protrusion 110 is shown as the depth ratio.

[0033] Furthermore, FIG. 7 shows the measured values ​​of D2 and H1, as well as the lightness index. This lightness index was measured using a color reader CR-20 manufactured by Konica Minolta Japan, Inc. The sample was large enough to cover the measurement opening (φ8 mm). The observation light source was D65, and the L component value of the L*a*b* display system (color space) was used as the lightness index. The smaller the lightness index, the more black it appears (the black density increases and the contrast increases), so for the purpose of achieving a black appearance in this embodiment, a smaller lightness index is desirable. Specifically, to achieve the effect of appearing black, a lightness index of 15 or less is desirable, and a lightness index of 10 or less is even more desirable.

[0034] Furthermore, the forming accuracy evaluation value is shown in Figure 7. This forming accuracy evaluation value is the value obtained by dividing the actual measured value of H1 by the design value of H1, and the closer this forming accuracy evaluation value is to 1.00, the higher the forming accuracy is, and it is desirable that it is between 0.85 and 1.15.

[0035] As shown in FIG. 7, the molding accuracy evaluation values ​​for Examples 1 to 3 and the Comparative Example were all within the range of 0.85 to 1.15, indicating good moldability. On the other hand, the Comparative Example had a brightness index of 17.6, indicating an insufficient effect of appearing black. Furthermore, Examples 1 and 2 had brightness indexes less than 9.0, indicating a very high effect of appearing black. From these results, it can be said that the protrusion height H1 of the protrusions 110 is preferably 0.6 mm to 1.4 mm, and more preferably 1.0 mm to 1.3 mm. Furthermore, it can be said that the depth of the recesses 111 is preferably 30% to 70% of the protrusion height H1 of the protrusions 110 (depth ratio of 0.3 to 0.7).

[0036] Furthermore, it is more desirable that the shape of the outer edge portion 113 be curved rather than flat. This is because if the outer edge portion 113 were flat, more light would be reflected in the same direction at the outer edge portion 113, reducing the effect of appearing black. Furthermore, if the radius of curvature of the curved surface of the outer edge portion 113 is large, it is expected that the adverse effect of reducing the effect of appearing black due to reflected light would be more likely to occur, similar to when the surface is flat. Therefore, it is desirable that the radius of curvature of the curved surface of the outer edge portion 113 is small, and the radius of curvature R is preferably 0.02 mm or less, and more preferably 0.01 mm or less.

[0037] Furthermore, the angle θ formed by the inclined surface of the conical body 112 and the reference plane 7a is preferably 60° or more and 80° or less, and more preferably 65° or more and 75° or less.

[0038] The tire 1 according to the present embodiment described above provides the following effects.

[0039] (1) The tire 1 according to this embodiment is a tire 1 having a pattern region 7 provided on at least a portion of the outer surface of a sidewall 3 in a state where it is visible as a region different from the surrounding area of ​​the portion, and the pattern region 7 has a plurality of protrusions 110 protruding from a reference surface 7a, and the protrusions 110 have a recess 111 having a cone-shaped inner surface, a cone-shaped body portion 112 that forms the outer periphery of the protrusion 110 and extends in a cone-shaped manner from the reference surface 7a in the direction in which the protrusion 110 protrudes, and an outer edge portion 113 that surrounds the recess 111, and the protrusion height of the protrusion 110 is 0.6 mm or more and 1.4 mm or less, and the depth of the recess 111 is 30% or more and 70% or less of the protrusion height of the protrusion 110.

[0040] This makes it possible to provide a tire with a higher black density than before, achieving high contrast, and with good moldability.

[0041] (2) In the tire 1 described in (1), the outer edge portion 113 is formed in a curved shape that smoothly connects the recess 111 and the conical body portion 112.

[0042] This increases the black density and further enhances the effect of high contrast. In addition, since the change in the degree of light reflection depending on the viewing angle is small, the change in the degree of blackness (brightness) can be reduced.

[0043] (3) In the tire 1 described in (2), the radius of curvature of the outer edge portion 113 is 0.02 mm or less.

[0044] This increases the black density and further enhances the effect of increasing contrast.

[0045] (4) In the tire 1 described in (1) or (2), the inclination angle of the conical body portion 112 with respect to the reference plane 7a is equal to or greater than 60° and equal to or less than 80°.

[0046] This increases the black density and further enhances the effect of increasing contrast.

[0047] (5) In the tire 1 described in (1) or (2), the protrusion 110 has a cross section perpendicular to the reference plane 7a, in which the inclined surface of the conical body portion 112 and the inclined surface of the recessed portion 111 are symmetrical.

[0048] This allows easy optical design including light absorption, and also makes it possible to make the light absorption effect uniform.

[0049] (Variations) The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible, and these are also within the scope of the present disclosure.

[0050] (Variation 1) In the embodiment, an example has been described in which the inclined surface of the conical body 112 and the inclined surface of the recess 111 are both conical surfaces. However, this is not limiting, and for example, at least one of the inclined surface of the conical body 112 and the inclined surface of the recess 111 may be formed as a pyramidal surface such as a square pyramid or a triangular pyramid.

[0051] (Modification 2) In the embodiment, an example has been described in which the radius of curvature in the cross section of the outer edge portion 113 is constant when the outer edge portion 113 is a curved surface. However, the present invention is not limited to this, and the outer edge portion 113 may have a shape that combines multiple different curved surfaces.

[0052] The embodiments and modifications may be used in combination as appropriate, but detailed description thereof will be omitted. The present disclosure is not limited to the above-described embodiments. [Explanation of symbols]

[0053] 1 tire 1a Unvulcanized tires 1s side 2 beads 3 Sidewall 3a outer surface 4 Tread 5. Decoration Area 5a Inner arc line 5b Outer arc line 6A Mark section 6B Pattern section 7 Pattern Area 7a Reference plane 7b UV development reference plane 10 Tire molding mold 11 sectors 11a Inner surface 12 Side Plate 12a Inner surface 110 Protrusion 111 recess 112 Conical body 113 outer edge

Claims

1. A tire having a pattern area provided on at least a portion of the outer surface of a sidewall in a state where it is visible as a part different from the surrounding area of ​​the part, The pattern area is provided with a plurality of protrusions protruding from a reference surface, The protrusion is a recess having a mortar-shaped inner surface; a cone-shaped body portion that forms the outer periphery of the protrusion and extends in a cone shape from a reference plane in a direction in which the protrusion protrudes; an outer edge portion surrounding the recessed portion, The protrusion has a protruding height of 0.6 mm or more and 1.4 mm or less, The tire, wherein the depth of the recess is 30% or more and 70% or less of the protruding height of the protrusion.

2. 2. The tire according to claim 1, The tire, wherein the outer edge portion is formed in a curved shape that smoothly connects the recess and the conical body portion.

3. 3. The tire according to claim 2, The radius of curvature of the outer edge is 0.02 mm or less.

4. The tire according to claim 1 or 2, The inclination angle of the conical body portion with respect to the reference plane is equal to or greater than 60° and equal to or less than 80°.

5. The tire according to claim 1 or 2, In the protrusion, the inclined surface of the conical body portion and the inclined surface of the recessed portion are symmetrical in a cross section perpendicular to the reference plane.

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