JP2013136336A - Tire and tire forming mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire which enhances on-ice performance and on-snow performance, and a tire forming mold for use in manufacturing (molding) of the tire.SOLUTION: In the tire, a plurality of protrusions are formed on at least a part of a tread of a tread part; and an outside diameter of the protrusion is in the range of 5-70 μm, and has a size of over zero times to 100 times or less of a distance between the protrusions. The tire forming mold has a tread molding surface for molding the tread of the tread part of the tire; a plurality of recesses are formed on at least a part of the tread molding surface; and an outside diameter of the recess is in the range of 5-70 μm, and has a size of over zero times to 100 times or less of a distance between the recesses.

Description

  The present invention relates to a tire and a tire molding die, and more particularly, to a tire excellent in performance on ice and on snow, and a tire molding die used for manufacturing the tire.

Conventionally, various devices have been made for winter tires in order to improve performance on ice and performance on snow.
For example, in Patent Document 1, by providing a plurality of sipes in each block formed in the tread portion, the edge component in the ground contact surface is increased and the snow biting effect is improved, so that the snow / ice road surface (frozen road surface or Techniques for improving running performance on snowy road surfaces have been proposed.
Further, for example, in Patent Document 2, in a tire having a tread rubber having a so-called cap-and-base structure composed of a cap rubber and a base rubber, the water removal performance is greatly improved by using foamed rubber as the cap rubber. Technologies for improving the performance on ice and on snow have been proposed.

  Further, for example, in Patent Document 3, as shown in FIG. 1A, with respect to the surface property of the tread portion 1 of the tire, the surface roughness is obtained by providing a protruding portion 2 having a sharp tip on the surface of the tread portion. There has been proposed a technique for increasing the on-ice performance and on-snow performance of a tire by increasing the friction and increasing the frictional force between the tire surface and the road surface.

JP 2002-192914 A JP-A-11-301217 JP 2009-67378 A

However, in the technique of providing sipes in the block described in Patent Document 1, if the number of sipes is increased too much, the rigidity of the block decreases and the block collapses easily. There was a problem that performance on ice and performance on snow deteriorated.
Moreover, in the technique using foamed rubber for the cap rubber described in Patent Document 2, the rigidity of the entire block may be lowered due to the use of foamed rubber, and the wear resistance of the tire is not always sufficient.
Furthermore, in the technique of providing a protrusion with a sharp tip on the surface of the tread described in Patent Document 3, since the rigidity of the protrusion is low, the tire is particularly large when the load on the front wheel is increased due to the nose dive of the vehicle. When a load is applied, the projection may be crushed and desired performance may not be obtained. That is, in the technique in which the protruding portion having a sharp tip is provided on the surface of the tread portion, as shown in FIG. 1B, the protruding portion 2 is crushed by contact with the road surface T, and the volume of the water removal gap 3 is reduced. However, as a result of the reduction in water removal, desired performance on ice and performance on snow may not be obtained. Therefore, the technique described in Patent Document 3 has room for further improvement in performance on ice and performance on snow.
In addition, as a result of repeated investigations by the inventors on tires employing the techniques described in Patent Documents 1 to 3, the cause of these conventional tires is not clear, but sufficient on-ice performance and especially when new. It was also found that there was a problem that performance on snow could not be obtained. Therefore, the techniques described in Patent Documents 1 to 3 have room for improving the performance on ice and the performance on snow especially when the tire is new.

  An object of the present invention is to solve the above problems, and to provide a tire with improved performance on ice and performance on snow, and a mold for molding a tire used for manufacturing (molding) the tire. To do.

The inventor has intensively studied to solve the above problems.
As a result, the present inventor can further improve the on-ice performance and on-snow performance of the tire by suppressing a decrease in block rigidity and a decrease in water removal if a predetermined microstructure is formed on the surface of the tread portion, and The inventors have found that sufficient performance on ice and performance on snow can be exhibited even when a tire is new, and the present invention has been completed.

This invention is made | formed based on said knowledge, The summary structure is as follows.
The tire of the present invention has a plurality of protrusions formed on at least a part of the tread surface, the outer diameter of the protrusions is 5 to 70 μm, and is 0 times the distance between the protrusions. It is characterized by being super 100 times or less. Thus, if a plurality of protrusions are formed on at least a part of the tread surface (the surface that contacts the road surface during traveling), the frictional force between the tire surface and the road surface can be reduced while suppressing a decrease in block rigidity. It can be increased to improve the on-ice performance and the on-snow performance of the tire. Moreover, if the outer diameter of the protrusions is in the range of 5 to 70 μm and more than 0 times and not more than 100 times the distance between the protrusions, it is possible to suppress a reduction in water removal.
Here, in the present invention, the “outer diameter” refers to the maximum diameter of the protrusion in a plan view. In the present invention, the “distance between protrusions” refers to the shortest distance between adjacent protrusions. The “outer diameter” and “distance between the protrusions” can be measured, for example, by photographing the tread surface with a scanning electron microscope.

The tire molding die of the present invention is a tire molding die having a tread surface molding surface for molding the tread portion tread surface of the tire, and a plurality of recesses in at least a part of the tread surface molding surface. The outer diameter of the recesses is 5 to 70 μm, and is more than 0 times and not more than 100 times the distance between the recesses. In this way, a plurality of recesses are formed in at least a part of the tread surface, and the outer diameter of the recesses is in the range of 5 to 70 μm and more than 0 times and not more than 100 times the distance between the recesses. This is because a tire having a large number of protrusions having a predetermined outer diameter on at least a part of the tread surface can be molded with excellent performance on ice and performance on snow.
Here, in the present invention, the “outer diameter” refers to the maximum diameter of the concave portion in plan view. In the present invention, “distance between recesses” refers to the shortest distance between recesses adjacent to each other. The “outer diameter” and “distance between the recesses” can be measured, for example, by photographing the tread surface molding surface with an electron microscope.

  ADVANTAGE OF THE INVENTION According to this invention, the tire mold which can shape | mold the tire which improved on-ice performance and on-snow performance, and this tire can be provided.

(A) It is a schematic sectional drawing which shows typically the tread part tread of the conventional tire. (B) It is a schematic sectional drawing which shows typically a mode that a tread part tread of a tire and a road surface contact at the time of load load of a tire. It is a tire width direction sectional view of the tire concerning one embodiment of the present invention. It is a figure which expands and shows typically the shape of a part of tread part tread of the tire shown in Drawing 2, (a) is a top view, and (b) is a tire width direction sectional view. It is a SEM image (scanning electron microscope image) of the tread part tread of an example of the tire of the present invention. 1 is a schematic partial perspective view schematically illustrating a part of a tire molding die according to an embodiment of the present invention. It is a figure which expands and shows typically the shape of a part of tread surface molding surface of the metal mold | die for tire shown in FIG. 5, (a) is a top view, (b) is a width direction sectional drawing. (A)-(c) is another example of the partial shape of the tread part tread of a tire.

  Hereinafter, the tire and the tire molding die of the present invention will be described. The tire according to the present invention is characterized in that a predetermined fine structure is formed on at least a part of a tread surface (surface that contacts the road surface), and a surface property (tread surface property) of the tread portion is a predetermined property. . The tire molding die according to the present invention is used for manufacturing the tire according to the present invention, and has a predetermined inner surface of the mold, specifically, at least a part of a tread surface molding surface for molding the tread portion tread surface of the tire. It is characterized in that the microstructure of the tread surface molding surface is formed to have a predetermined property.

<Tire>
FIG. 2 is a sectional view in the tire width direction of one embodiment of the tire of the present invention.
As shown in FIG. 2, the tire 20 of the present embodiment includes a pair of bead portions 4, a pair of sidewall portions 5 that extend outward from each bead portion 4 in the tire radial direction, and the sidewall portions 5. And a tread portion 6 extending across.
Further, the tire 20 of the present embodiment includes a carcass 7 straddling a toroidal shape between a pair of bead cores 4a embedded in the pair of bead portions 4, and a two-layer belt disposed on the outer side in the tire radial direction of the carcass 7. A belt 8 composed of layers 8a and 8b. Further, a tread rubber made of non-foamed rubber is disposed outside the belt 8 in the tire radial direction.

Here, in the tire 20, microprojections having a predetermined shape are formed on at least a part (all in this embodiment) of the tread surface. Specifically, FIG. 3A shows an enlarged plan view of the tread surface 6a of the tread portion 6, FIG. 3B shows an enlarged cross-sectional view along the tire width direction on the tread portion tread surface 6a side, and FIG. As shown in the SEM photograph of the surface of the tread surface, the tire according to the present embodiment has a large number of minute protrusions 9 having an outer diameter D of 5 to 70 μm on the entire tread surface 6a. In the tire according to the present embodiment, the protrusion 9 has an outer diameter D in the range of more than 0 times and not more than 100 times the shortest distance L between the adjacent protrusions 9.
FIG. 3 shows a case where the protrusion 9 is a hemispherical protrusion, but in the tire of the present invention, the protrusion is a truncated cone or truncated pyramid, as shown in FIG. A trapezoidal cross section as shown in FIG. 7, a rectangular shape such as a cylinder or a prism, and a truncated hemispherical shape as shown in FIG. 7C. It can be of various shapes.

And in this tire 20, since many protrusions 9 are formed on the tread surface of the tread, it is possible to sufficiently improve the on-ice performance and on-snow performance of the tire while suppressing a decrease in block rigidity and a decrease in water removal. Can do.
That is, since the tire 20 has a large number of protrusions 9, the water film on the road surface is removed using the gaps between the protrusions 9 at the time of contact with the road surface (water removal is demonstrated). be able to. Moreover, the frictional force between the tread portion tread surface and the road surface can be increased, and the on-ice performance and on-snow performance of the tire can be improved.
Furthermore, in this tire 20, since the outer diameter D of the protrusion 9 is 5 μm or more, the rigidity of the protrusion 9 can be ensured, and even when a large load is applied to the tire, the protrusion 9 Is difficult to be crushed and water removal can be secured. Furthermore, in this tire 20, since the outer diameter D of the protrusions 9 is 70 μm or less, even when a large number of protrusions 9 are formed, the volume of the gaps between the protrusions 9 is ensured to remove water. Can be increased.
Further, in the tire 20, since the outer diameter D of the protrusion 9 is more than 0 times the shortest distance L between the adjacent protrusions 9, the frictional force between the tread portion tread surface and the road surface is sufficiently increased. In addition, it is possible to secure the rigidity of the protruding portion 9 and enhance water removal. Further, in the tire 20, since the outer diameter D of the protrusions 9 is 100 times or less the shortest distance L between the protrusions 9, the void volume between the protrusions 9 can be ensured and water removal can be improved. it can.
In the tire 20, since the minute protrusions 9 having a predetermined outer diameter D are arranged at predetermined intervals, it is possible to suppress the reduction of water removal and improve the performance on ice and the performance on snow. There is no need to form an excessive number of sipes or use foam rubber. The cause of the tire 20 is not clear, but sufficient on-ice performance and on-snow performance can be exhibited even when it is new (unused state).

Therefore, according to the tire 20, it is possible to further suppress the on-ice performance and the on-snow performance of the tire even when it is new by suppressing the decrease in block rigidity and the decrease in water removal.
In the tire of the present invention, a protrusion having an outer diameter D of less than 5 μm or more than 70 μm may be formed on the tread surface. In this case, the protrusion of the protrusion having an outer diameter D of less than 5 μm or more than 70 μm may be formed. The number is preferably 10% or less of the total number of protrusions. This is because if the protrusions having an outer diameter D of less than 5 μm or more than 70 μm are 10% or less of the total protrusions, the effect obtained by forming the protrusions can be sufficiently increased. Incidentally, in the tire of the present invention, when the outer diameter D is less than 5 μm or more than 70 μm is formed on the tread surface, the outer diameter D is the shortest distance L between the protrusions in all the protrusions. It is preferably more than 0 times and 100 times or less. If the outer diameter D of all the protrusions is more than 0 times and not more than 100 times the shortest distance L, the frictional force between the tread surface and the road surface can be sufficiently increased, and water removal can be improved. Because it can.
The “number of protrusions having an outer diameter D of less than 5 μm or more than 70 μm” can be measured by photographing the tread surface with an electron microscope.

Here, in the tire 20, it is preferable that the outer diameter D of the protruding portion 9 is 10 to 20 μm. This is because if the protrusion 9 has an outer diameter of 10 μm or more, the rigidity of the protrusion 9 can be increased and sufficient water removal can be ensured. In addition, if the outer diameter D of the protrusions 9 is 20 μm or less, even when a large number of protrusions 9 are formed, a sufficient volume of voids between the protrusions 9 can be secured to enhance water removal. Because you can.
Further, in the tire 20, the outer diameter D of the protrusions 9 is preferably 30 to 100 times the shortest distance L between the protrusions 9. If the outer diameter D of the protrusion 9 is 30 times or more the minimum distance L, the frictional force between the tread surface and the road surface can be increased sufficiently, and the rigidity of the protrusion 9 can be secured and removed. This is because the aqueous property can be increased. Further, if the outer diameter D of the protrusion 9 is 100 times or less of the shortest distance L, the volume of the gap between the protrusions 9 can be secured and water removal can be enhanced.

  Moreover, in this tire 20, it is preferable that the shape of the projection part 9 is hemispherical. This is because if the shape of the protrusion 9 is hemispherical, the protrusion 9 is not easily crushed and water removal can be ensured.

Furthermore, in the tire 20, it is preferable that the height H of the protrusion 9 formed on the tread surface is 1 to 50 μm. This is because if the height H of the protrusions 9 is 1 μm or more, a sufficient volume of the gaps between the protrusions 9 can be secured and water removal can be enhanced. Further, if the height H of the protrusion 9 is 50 μm or less, the rigidity of the protrusion 9 can be increased and sufficient water removal can be ensured.
Note that the height of the solid foam-like protrusion 9 is such that the first virtual plane perpendicular to the tire radial direction line extending through the tip (the outer end in the tire radial direction) of the solid foam-like protrusion 9 and the solid foam The distance along the tire radial direction between the second virtual plane closest to the first virtual plane among the virtual planes that are in contact with the outer contour line of the protrusion 9 and are orthogonal to the tire radial direction line. .
In addition, the height of the protrusion part 9 can be measured with SEM and a microscope.

Moreover, in this invention, it is preferable that many protrusion parts formed in at least one part of a tread part tread are solid foam-like protrusion parts whose outer diameter D is 5-70 micrometers. Thus, if a large number of solid foam-like protrusions are formed on at least a part of the tread surface, the frictional force between the tire surface and the road surface can be further increased while further suppressing the block rigidity. Further, the on-ice performance and on-snow performance of the tire can be further improved. Moreover, if the outer diameter of a solid foam-like projection part is set within a range of 5 to 70 μm, a reduction in water removal can be further suppressed. That is, by forming a large number of solid foam-like projections, the water film on the road surface is removed by utilizing the gaps between the solid foam-like projections at the time of contact with the road surface (exhibiting water removal). be able to. Moreover, the frictional force between the tread portion tread surface and the road surface can be increased, and the on-ice performance and on-snow performance of the tire can be further improved.
Furthermore, since the shape of the solid foam-like protrusion is a solid foam (for example, hemispherical), it is easy to apply a force evenly to the solid foam-like protrusion, and when a large load is applied to the tire. Even if it exists, a solid foam-like projection part is hard to be crushed, and also water removal can be ensured.
Further, since the outer diameter D of the solid foam-like protrusion is 5 μm or more, the rigidity of the solid foam-like protrusion can be ensured, and even when a large load is applied to the tire, the solid foam-like protrusion can be solid. It is difficult for the foamy protrusions to be crushed, and water removal can be ensured. Furthermore, since the outer diameter D of the solid foam-like protrusions is 70 μm or less, even when a large number of protrusions are formed, the volume of the voids between the solid foam-like protrusions is ensured, and water removal is performed. Can be increased.
For the same reason, in the present invention, the outer diameter D of the solid foam projection is more preferably 10 to 20 μm. That is, if the outer diameter of the solid foam projection is 10 μm or more, the rigidity of the solid foam projection can be further increased and sufficient water removal can be ensured. Further, if the outer diameter D of the solid foam projections is 20 μm or less, the volume of the space between the solid foam projections can be further increased even when a large number of solid foam projections are formed. This is because it is possible to ensure water removal and enhance water removal.
Here, in the present invention, the “solid foam projection” is a projection made of a solid foam, and the “solid foam” is, for example, hemispheric, Shapes such as a hemisphere, a truncated cone, a truncated pyramid, a cylinder, and a prism are included.

In the tire of the present invention, it is preferable that a large number of protrusions having an outer diameter D of 70 μm or less are uniformly formed on at least a part of the tread surface.
In this way, if a large number of protrusions are uniformly formed on at least a part of the tread surface, the friction between the tire surface and the road surface can be suppressed while suppressing a decrease in block rigidity in all directions. The force can be increased, and the on-ice performance and on-snow performance of the tire can be improved. Moreover, if the outer diameter of the protrusion is set to 70 μm or less, it is possible to suppress a decrease in slow water.
That is, by forming a large number of protrusions uniformly, the above-described water removal and frictional force can be improved in all directions. Furthermore, by setting the outer diameter of the protrusions to 70 μm or less, as described above, the volume of the gaps between the protrusions can be ensured, and the slow water can be increased.
“Uniform” means that the number density of the protrusions is the same regardless of the cross section of the tread surface. Specifically, “uniform” means that the number density of protrusions when viewed in a cross section where the number density is maximum is three times the number density of protrusions when viewed in a cross section where the number density is minimum. Indicates the following.

Further, in the tire according to the present invention, a large number of protrusions having a convex shape outward in the tire radial direction are formed on at least a part of the tread surface, and the protrusion has a center of curvature on the inner side in the tire radial direction from the tread surface. And the radius of curvature of the protrusion is preferably 1 μm or more and 70 μm or less.
In this way, if a large number of protrusions are formed on at least a part of the tread surface, the frictional force between the tire surface and the road surface is increased while suppressing the decrease in block rigidity, and the on-ice performance of the tire is increased. And the performance on snow can be improved. Further, in this tire, the protrusion has a convex shape on the outer side in the tire radial direction, has a curvature center on the inner side in the tire radial direction from the tread surface, and further has a curvature radius of 1 μm or more. The shape of the part is a highly rigid shape. On the other hand, since the radius of curvature of the protrusions is 70 μm or less, it is possible to secure the volume of the gaps between the protrusions and suppress the reduction in water removal.
In addition, it is preferable that the curvature radius of the projection part 9 is 1 micrometer or more and 50 micrometers or less. This is because if the radius of curvature of the protrusion 9 is 1 μm or more, the rigidity of the protrusion 9 can be increased and sufficient water removal can be ensured. Further, if the radius of curvature of the protrusions 9 is 50 μm or less, even if a large number of protrusions 9 are formed, a sufficient volume of voids between the protrusions 9 can be secured to improve water removal. Because it can.
Here, in the present invention, the “curvature radius” means 0.5 times the maximum diameter of the protrusion in the tire width direction sectional view. However, it shall be seen in the cross section where the curvature radius is maximum. The “curvature radius” can be measured, for example, by photographing the cross section of the protrusion with an electron microscope. Note that the “projection shape in the tire radial direction” includes, for example, shapes such as a hemisphere and a truncated hemisphere.
In the tire of the present invention, the tread portion tread may have a center of curvature on the inner side in the tire radial direction from the tread portion tread, and a protrusion having a curvature radius of less than 1 μm or more than 70 μm may be formed. In this case, it is preferable that the number of protrusions having a center of curvature on the inner side in the tire radial direction from the tread surface and having a radius of curvature of less than 1 μm or more than 70 μm is 10% or less of the total number of protrusions. If the center of curvature is located on the inner side in the tire radial direction from the tread surface, and the projection radius is less than 1 μm or more than 70 μm is 10% or less of the total projection, the effect obtained by the formation of the projection is sufficiently large. Because it can be done.
Incidentally, “the number of protrusions having a radius of curvature of less than 1 μm or more than 70 μm” can be measured by photographing the tread portion with an electron microscope.

Here, it is preferable that the ten-point average roughness Rz of the tread surface of the tire on which the hemispherical protrusion is formed is 1.0 to 50 μm.
This is because when Rz is 1.0 μm or more, a void for water removal can be secured, while when Rz is 50 μm or less, a contact area with the road surface can be secured. is there. By these, the performance on ice and the performance on snow of a tire can further be improved.
Here, “ten-point average roughness Rz” is measured in accordance with the provisions of JIS B0601 (1994), and is obtained with a reference length of 0.8 mm and an evaluation length of 4 mm. is there.

Moreover, it is preferable that the average space | interval S of the local peak of the projection part formed in the tread part tread of a tire is 5.0-100 micrometers.
This is because, when the average interval S is 5.0 μm or more, a void for water removal can be ensured, and on the other hand, when the average interval S is 100 μm or less, a contact area with the road surface is ensured. Because you can. By these, the performance on ice and the performance on snow of a tire can further be improved.
Here, the “average distance between local peaks” is measured in accordance with JIS B0601 (1994), and the reference length is 0.8 mm and the evaluation length is 4 mm.

Further, the distribution of the outer diameters of the protrusions is 50 to 60% for protrusions having an outer diameter of 5 μm to less than 30 μm, 15 to 20% for protrusions having an outer diameter of 30 μm to less than 50 μm, and 50 μm to 70 μm of outer diameters on a number basis. The following protrusions are preferably 10 to 20%.
This is because the protrusions can be arranged densely, thereby increasing the contact area and improving the on-ice performance and on-snow performance of the tire.
In addition, although the protrusion part with an outer diameter of less than 5 micrometers or more than 70 micrometers may be contained, it is preferable that it is 10% or less of the whole number.

  And the tire mentioned above can be manufactured using the following molds for tire molding, without being specifically limited. The tire molding using the following tire molding die can be performed according to a conventional method.

<Tire molds>
FIG. 5 is a schematic partial perspective view showing a part of a tire molding die used for molding the tire of the present invention.
As shown in FIG. 5, the mold 10 has a molding surface 11 for vulcanizing and molding a tire.
This molding surface 11 has a tread surface molding surface 11a that forms a tread portion tread surface. In the illustrated example, a side wall molding surface 11b that molds the outer surface of the sidewall portion and a bead portion molding that molds the outer surface of the bead portion. It also has a surface 11c.
Although this shaping | molding surface 11 is not specifically limited, For example, it can form with aluminum.
The tread portion tread having the above-described surface property of the tire of the present invention can be formed by a tire molding die 10 including a tread surface molding surface 11a having a surface property corresponding to the surface property. Specifically, FIG. 6A shows an enlarged plan view of the tread forming surface 11a, and FIG. 6B shows an enlarged cross-sectional view along the width direction on the tread forming surface 11a side of the mold 10. The tire molding die 10 according to the present embodiment has a large number of minute hemispherical concave portions 12 having an outer diameter d of 5 to 70 μm on the entire tread surface molding surface 11 a of the die 10. Further, in the tire molding die 10 according to the present embodiment, the outer diameter d of the recess 12 is in the range of more than 0 times and not more than 100 times the shortest distance l between the recesses 12 adjacent to each other.
FIG. 6 shows the case where the concave portion 12 is a hemispherical concave portion. However, in the mold of the present invention, the concave portion 12 has a truncated hemispherical shape, a truncated cone shape, a truncated pyramid shape, and a cylindrical shape. Alternatively, it may be a prismatic recess.
That is, in the vulcanizing process of the tire using the mold 10, the hemispherical concave shape of the tread surface molding surface 11a of the mold 10 is transferred as the projection shape of the tread surface of the tire. And the tread part tread of the manufactured tire is hemispherical, the outer diameter D is 5 to 70 μm, and the protruding part 9 is more than 0 times and not more than 100 times the distance L between the adjacent protruding parts 9. Is formed. Therefore, a tire excellent in performance on ice and on snow can be formed.
In the mold according to the present invention, recesses having an outer diameter d of less than 5 μm or more than 70 μm may be formed on the tread surface. In this case, the number of recesses having an outer diameter d of less than 5 μm or more than 70 μm. Is preferably 10% or less of the total number of recesses. This is because a sufficient number of protrusions can be formed on the tread surface of the tire if the recesses having an outer diameter d of less than 5 μm or more than 70 μm are 10% or less of all the recesses. Incidentally, in the mold according to the present invention, when a recess having an outer diameter d of less than 5 μm or more than 70 μm is formed on the molding surface of the tread, the outer diameter d is 0 of the shortest distance l between the recesses in all the recesses. It is preferable that it is more than 100 times and less than 100 times. This is because if the outer diameter d of all the recesses is more than 0 times and not more than 100 times the shortest distance l, projections can be formed at appropriate intervals on the tread surface of the tire.
The “number of recesses having an outer diameter d of less than 5 μm or more than 70 μm” can be measured by photographing the tread molding surface with an electron microscope.
Hereinafter, a method for forming the tread surface molding surface 11a of the mold 10 will be described.

The tread surface molding surface 11a can be formed by a projection material projection process in which a projection material having a specific shape is projected and collided with the molding surface. The tire molding die obtained through this projecting material projecting step has a tread surface molding surface having an outer diameter d of 5 to 70 μm as described above and more than 0 times the shortest distance l between the adjacent recesses 12. Since the tire has a large number of recesses 12 within a range of 100 times or less, the tread surface of the tire vulcanized using this mold has an outer diameter D of 5 to 70 μm as described above, and In addition, a large number of protrusions having a distance L between adjacent protrusions 9 that is greater than 0 times and not more than 100 times the distance L are provided.
Here, in the projection material projecting step, the tread surface molding surface 11a (entire surface or part) is preferably formed by projecting and colliding a spherical projection material having a sphericity of 15 μm or less.
This is because, by setting the sphericity of the projection material to 15 μm or less, it is possible to form a large number of concave portions having desired properties on the molding surface of the mold of the mold, and the tire molded using this mold This is because the tread surface can be formed into a desired surface shape.

The sphericity of the projection material is more preferably 10 μm or less.
If the sphericity of the projection material is set to 10 μm or less, it is possible to easily form a large number of concave portions having desired properties on the molding surface of the mold, so that the tread surface of the tire formed using the mold is used. This is because it is possible to form a tire having more excellent performance on ice and performance on snow by forming a large number of protrusions having a desired shape.
The sphericity of the projection material is more preferably 5 μm or less.
This is because a recess having a desired property can be more easily formed on the tread surface molding surface of the mold.

Here, it is preferable that the average particle diameter of the projection material used for a projection material projection process is 10 micrometers-1 mm.
Because, by setting the average particle size of the projection material to 10 μm or more, it becomes easier to obtain a mold having a desired concave shape on the tread surface molding surface, and in the projection material projection step, when projecting under high pressure This is because the projection material can be prevented from being scattered around. On the other hand, by setting the average particle diameter of the projection material to 1 mm or less, it is possible to prevent the mold surface from being worn at an early stage.
For the same reason, the average particle diameter of the projection material is more preferably 20 μm to 0.7 mm, and further preferably 30 μm to 0.5 mm.
Here, the “average particle size” is a photograph of the projection material taken by SEM, and 10 projection materials are taken out arbitrarily, and the average of the diameter of the inscribed circle and the diameter of the circumscribed circle in contact with each of the projection materials is calculated. The value obtained by averaging these values with the ten projectiles shall be referred to.

Moreover, it is preferable that the Mohs hardness of a projection material shall be 2-10.
This is because by setting the Mohs hardness of the projection material to 2 or more, it becomes easier to obtain a mold having a desired concave shape on the tread surface molding surface. On the other hand, by setting the Mohs hardness of the projection material to 10 or less, it is possible to reduce the early damage to the mold.
For the same reason, the Mohs hardness of the projection material is more preferably 3.0 to 9.0, and even more preferably 5.0 to 9.0.
Further, the Mohs hardness of the tread surface molding surface of the tire molding die is preferably 2.0 to 5.0, and the difference in the Mohs hardness between the tread surface molding surface of the tire molding die and the projection material is It is preferable that it is 3.0-5.0.

Furthermore, the specific gravity of the projection material is preferably 0.5-20.
This is because by setting the specific gravity of the projection material to 0.5 or more, it is possible to improve the workability by suppressing the scattering of the projection material in the projection process. On the other hand, by setting the specific gravity of the projection material to 20 or less, energy for accelerating the projection material can be reduced, and early wear of the mold can be suppressed.
For the same reason, the specific gravity of the projection material is more preferably 0.8-18, and further preferably 1.2-15.

  Here, the material of the projection material is not particularly limited, but for example, it is preferable to use gyricon, iron, cast steel, ceramics, or the like.

Moreover, in a projection material projection process, it is preferable to project a projection material on the tread surface shaping | molding surface of the said metal mold | die with 100-1000 kPa high pressure air for 30 second-10 minutes.
Because, by projecting the projection material at 100 kPa or more for 30 seconds or more, the tread surface can be uniformly formed into the desired shape described above, while the projection material is projected at 1000 kPa or less and 10 minutes or less. This is because it is possible to suppress damage to the tread surface molding surface.
In addition, it is preferable to set the projection speed of the projection material to 0.3 to 10 (m / s) by adjusting the specific gravity and the projection pressure of the projection material, and to 0.5 to 7 (m / s). More preferred.
At this time, the distance between the projection nozzle of the projection material and the tire molding die is preferably 50 to 200 (mm).
Here, the projection time of the above-mentioned projection material means the projection time per mold, for example, when molding a tire using nine molds, nine molds for molding one tire It is preferable to project the projecting material onto the mold surface of the mold for a total of 270 seconds to 90 minutes.
In addition, the projection of the projection material onto the tread surface molding surface of one mold can be performed while shifting the position projected by the operator while considering the shape of the mold. In this way, the projection material can be projected more uniformly.

Here, in this metal mold | die 10, it is preferable that the outer diameter d of the recessed part 12 is 10-20 micrometers. This is because if the outer diameter d of the recess 12 is 10 to 20 μm, the protruding portion 9 having an outer diameter D of 10 to 20 μm can be formed on the tread surface of the tire. Note that the outer diameter d of the recess 12 can be controlled by adjusting the particle size of the projection material. Specifically, when the particle diameter of the projection material is increased, the outer diameter d can be increased.
Further, in the mold 10, the outer diameter d of the recess 12 is preferably 30 to 100 times the shortest distance l between the recesses 12. If the outer diameter d of the recess 12 is 30 to 100 times the shortest distance l, the protrusion 9 having an outer diameter D of 30 to 100 times the shortest distance L between the protrusions 9 is formed on the tread surface of the tire. Because it can. The shortest distance l between the recesses 12 can be controlled by adjusting the particle size of the projection material. Specifically, the distance l can be reduced by increasing the particle size of the projection material.

  Moreover, in this metal mold | die 10, it is preferable that the shape of the recessed part 12 is hemispherical. This is because if the shape of the recess 12 is hemispherical, the hemispherical protrusion 9 can be formed on the tread surface of the tire. In addition, the shape of the recessed part 12 can be controlled by adjusting the particle size, the injection speed, and the projection angle of the projection material.

Furthermore, in this mold 10, the depth h of the recess 12 is preferably 1 to 50 μm. This is because if the depth h of the recess 12 is 1 to 50 μm, the protrusion 9 having a height of 1 to 50 μm can be formed on the tread surface of the tire. Note that the depth h of the recess 12 can be controlled by adjusting the projection speed of the projection material. Specifically, the depth h can be increased by increasing the projection speed of the projection material.
Here, the depth of the concave portion 12 is in contact with the third virtual plane perpendicular to the radial line extending through the deepest portion (radial outer end) of the concave portion 12 and the outer contour line of the concave portion 12 and the radial line. A distance along the radial direction between the fourth virtual plane closest to the third virtual plane among the virtual planes orthogonal to the first virtual plane. Incidentally, the “radial direction” refers to a radial direction of an annular tread surface molding surface, that is, a direction corresponding to a tire radial direction of a tire molded using the mold 10.
In addition, the depth of the recessed part 12 can be measured with SEM and a microscope.

Here, the mold of the present invention is a mold for molding a tire, and has a tread surface molding surface for molding a tread portion tread surface of the tire, and at least a part of the tread surface molding surface has an outer diameter. It is preferable to have a large number of broken bubble-shaped recesses of 5 to 70 μm. In this way, if a large number of bubble-breaking concave portions having an outer diameter d of 5 to 70 μm are formed on at least a part of the tread surface, the solid foam shape having an outer diameter D of 5 to 70 μm on at least a part of the tread surface. This is because it is possible to form a tire having a large number of protrusions and having excellent performance on ice and performance on snow.
Here, in the present invention, the “bubble-breaking concave portion” is a shape corresponding to the outer shape of the foam, which is formed at the place where the foam was located when the foam broke. Refers to a recess. The “bubble-breaking recess” includes, for example, recesses such as a hemisphere, a truncated hemisphere, a truncated cone, a truncated pyramid, a cylinder, and a prism.
In the mold of the present invention, a bubble-shaped recess having an outer diameter d of less than 5 μm or more than 70 μm may be formed on the tread molding surface. In this case, the outer diameter d is less than 5 μm or more than 70 μm. It is preferable that the number of broken bubble-shaped concave portions is 10% or less of the total number of broken bubble-shaped concave portions. A sufficient number of solid foam-like protrusions can be formed on the tread surface of the tire if the bubble-breaking recess having an outer diameter d of less than 5 μm or more than 70 μm is 10% or less of the total bubble-breaking recess. Because.
Incidentally, the “number of bubble-shaped recesses having an outer diameter d of less than 5 μm or more than 70 μm” can be measured by photographing the tread surface with an electron microscope.
Here, in this metal mold | die 10, it is preferable that the outer diameter d of a bubble-shaped recessed part is 10-20 micrometers. This is because if the outer diameter d of the broken bubble-shaped recess is 10 to 20 μm, solid foam-like protrusions having an outer diameter D of 10 to 20 μm can be formed on the tread surface of the tire.
Note that the outer diameter d of the bubble-breaking concave portion can be controlled by adjusting the particle size of the projection material. Specifically, when the particle diameter of the projection material is increased, the outer diameter d can be increased.
Moreover, in this metal mold | die, it is preferable that the shape of a bubble-shaped recessed part is a hemisphere. This is because if the shape of the bubble-breaking concave portion is hemispherical, a hemispherical solid foam-like protrusion can be formed on the tread surface of the tire. Note that the shape of the bubble-breaking concave portion can be controlled by adjusting the particle size, spray speed, and projection angle of the projection material.

Furthermore, the tire molding die of the present invention is a tire molding die having a tread surface molding surface for molding the tread portion tread surface of the tire, and at least a part of the tread surface molding surface has an outer diameter. Preferably has a large number of recesses of 70 μm or less.
As described above, when a large number of recesses having an outer diameter of 70 μm or less are uniformly formed on at least a part of the tread surface, the ice surface having a large number of protrusions having an outer diameter of 70 μm or less on at least a part of the tread surface. This is because a tire excellent in performance and performance on snow can be molded.
Here, the tread surface molding surface of the mold preferably has a large number of recesses having an outer diameter of 20 μm or less on at least a part of the tread surface molding surface. In this way, a large number of protrusions having an outer diameter of 20 μm or less can be uniformly formed on at least a part of the tread surface of the formed tire, and a tire excellent in performance on ice and on snow can be formed. Because you can.
Here, in the present invention, “uniform” means that the number density of recesses is the same regardless of the cross section of the tread surface molding surface. Specifically, “uniform” means that the number density when viewed in a section where the number density of recesses is maximum is not more than 3 times the number density when viewed in a section where the number density is minimum. It shall be said.
The outer diameter d of the recess 12 can be controlled by adjusting the particle size of the projection material. Specifically, when the particle diameter of the projection material is increased, the outer diameter d can be increased.
In addition, the uniform formation of the recesses on the tread surface can be achieved by reducing the particle size of the projection material.

In addition, the tire molding die of the present invention is a tire molding die having a tread surface molding surface for molding a tread portion tread surface of the tire, and a recess is formed on at least a part of the tread surface molding surface. It is preferable that a large number of the recesses have a center of curvature outside the mold (inside in the radial direction of the annular mold 10), and the curvature radius of the recess is 1 μm or more and 70 μm or less.
Thus, at least a part of the tread part tread surface is formed on at least a part of the tread part tread surface by forming a plurality of recesses having a curvature center outside the mold and a curvature radius of 1 μm or more and 70 μm or less on at least a part of the tread surface molding surface. This is because it is possible to form a tire that has a center of curvature on the inner side in the tire radial direction from the tread portion tread surface and has a large number of protrusions with a radius of curvature of 1 μm or more and 70 μm or less and excellent in ice performance and snow performance.
In addition, it is more preferable that the tread surface molding surface of the mold has a plurality of concave portions having a curvature center outside the mold and having a curvature radius of 1 μm or more and 50 μm or less on at least a part of the tread surface molding surface. At least a part of the tread portion tread of the formed tire has a center of curvature on the inner side in the tire radial direction from the tread portion tread, and a protrusion having a convex shape outward in the tire radial direction with a radius of curvature of 1 μm to 50 μm. This is because the tire can be molded so as to have a large number of tires, and a tire having further excellent performance on ice and performance on snow can be formed.
Here, in the present invention, the “curvature radius” means 0.5 times the maximum diameter of the recess in the tire width direction sectional view. However, it shall be seen in the cross section where the curvature radius is maximum. The “curvature radius” can be measured, for example, by photographing the cross section of the recess with an electron microscope. The “concave portion” mentioned here includes shapes such as a hemispherical shape and a truncated hemispherical shape.
In addition, the curvature radius of the recessed part 12 can be controlled by adjusting the particle size, projection angle, etc. of a projection material. Specifically, when the particle diameter of the projection material is increased, the radius of curvature can be increased.
Incidentally, the mold of the present invention may have a center of curvature outside the mold and a recess having a radius of curvature of less than 1 μm or more than 70 μm. In this case, the center of curvature is outside the mold. The number of recesses having a curvature radius of less than 1 μm or more than 70 μm is preferably 10% or less of the total number of recesses. If the concave portion having a center of curvature outside the mold and having a radius of curvature of less than 1 μm or more than 70 μm is 10% or less of the total concave portion, a sufficient number of protrusions can be formed on the tread surface of the tire. Because.
Incidentally, “the number of recesses having a radius of curvature of less than 1 μm or more than 70 μm” can be measured by photographing the tread surface with an electron microscope.

Here, it is preferable that the ten-point average roughness Rz of the tread surface molding surface of the mold is 1.0 to 50 μm. This is because a tire having a 10-point average roughness Rz of the tread portion tread of 1.0 to 50 μm can be formed.
In addition, by setting the average particle size of the projection material used in the projection material projecting step to 50 to 400 μm, it is possible to obtain a tire molding die having a tread surface molding surface having a ten-point average roughness Rz in the above range. .

Moreover, it is preferable that the average space | interval of the local peak of the recessed part of the tread surface molding surface of a metal mold | die is 5.0-100 micrometers. This is because the tire can be molded with an average distance S between the local peaks of the protrusions formed on the tread surface of the tire being 5.0 to 100 μm.
In addition, the tire molding die provided with the tread surface molding surface which has the average space | interval S of said range can be obtained by making the average particle diameter of the projection material used in a projection material projection process into 50-400 micrometers.

In addition, the distribution of the outer diameters of the recesses on the molding surface of the tread of the mold is 50-60% for recesses with an outer diameter of 5 μm or more and less than 30 μm, 15-20% for recesses with an outer diameter of 30 μm or more and less than 50 μm, and It is preferable that the concave portion having a diameter of 50 μm or more and 70 μm or less is 10 to 20%. In addition, although you may have a recessed part whose outer diameter is less than 5 micrometers or more than 70 micrometers, it is preferable that it is 10% or less of the whole number.
The outer diameter distribution of the protrusions is 50 to 60% for protrusions having an outer diameter of 5 μm to less than 30 μm, 15 to 20% for protrusions having an outer diameter of 30 μm to less than 50 μm, and 10 protrusions having an outer diameter of 50 μm to 70 μm. This is because it is possible to form a tire that is ˜20%.
In addition, the particle size distribution of the projection material used in the projection material projection step is 10 to 20% for the projection material of 50 μm or more and less than 200 μm, 50 to 60% for the projection material of 200 μm or more and less than 300 μm, and 300 μm or more and 400 μm on the basis of the number. By setting the following projection material to 10 to 20%, it is possible to obtain a tire molding die including a tread surface molding surface having a concave portion with an outer diameter distribution in the above range. Note that a projection material having a particle size of less than 50 μm and more than 400 μm may be included.

  As mentioned above, although embodiment of this invention was described with reference to drawings, the tire of this invention and the metal mold | die for tire shaping are not limited to the example mentioned above, The tire and the metal mold | die for tire shaping | molding of this invention are used. Can be modified as appropriate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all.

(Manufacture of tire molds)
A projection material (ceramic system) is projected on the tread molding surface of an aluminum tire molding mold by changing the projection conditions (projection pressure, projection speed, etc.), and the tread molding surface having the surface properties shown in Table 1 is used. The tire molding dies 1 to 4 were produced. In addition, the surface property of the tread surface molding surface of the produced mold was measured using an SEM and a microscope.

(Tire manufacturing)
Tires 1 to 4 having a tire size of 205 / 55R16 were produced using the produced tire molding dies 1 to 4 respectively according to a conventional method. And the surface property of the tread part tread of the produced tire was measured using SEM and a microscope. The results are shown in Table 2.
Further, the performance on ice and the performance on snow of each tire produced were evaluated by the following evaluation methods. The results are shown in Table 2.

<Performance on ice>
The tire immediately after fabrication was assembled into the applicable rim, filled with the regular internal pressure prescribed in JATMA and mounted on the vehicle. Then, the friction coefficient on ice was measured on a freezing road under the condition of a speed of 30 km / h with the load per front wheel being 4.3 kN. The friction coefficient on ice of each tire was indexed with the friction coefficient on ice of the tire 1 being 100. Table 2 shows the results. In Table 2, the larger the numerical value, the greater the coefficient of friction on ice and the better the performance on ice.
<Snow performance>
The tire immediately after fabrication was assembled into the applicable rim, filled with the regular internal pressure prescribed in JATMA and mounted on the vehicle. Then, the friction coefficient on snow was measured under the condition of a speed of 30 km / h on a snowy road with a load per front wheel set to 4.3 kN. The tire friction coefficient on snow of the tire 1 was set to 100, and the friction coefficient on snow of each tire was evaluated as an index. Table 2 shows the results. In Table 2, the larger the numerical value, the greater the friction coefficient on snow and the better performance on snow.

  As shown in Table 2, it can be seen that the tire according to the example is superior in performance on ice and on snow than the tires according to the comparative example and the conventional example.

  ADVANTAGE OF THE INVENTION According to this invention, the tire mold which can shape | mold the tire which improved on-ice performance and on-snow performance, and this tire can be provided.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Protrusion part 3 Space | gap 4 Bead part 4a Bead core 5 Side wall part 6 Tread part 6a Tread surface 7 Carcass 8 Belt 8a, 8b Belt layer 9 Protrusion part 10 Mold 11 Molding surface 11a Tread surface molding surface 11b Side wall part molding surface 11c Bead forming surface 12 Recess 20 Tire T Road surface

Claims (2)

A plurality of protrusions are formed on at least a part of the tread surface,
The outer diameter of the protrusion is 5 to 70 μm, and is more than 0 times and not more than 100 times the distance between the protrusions. A mold for tire molding,
It has a tread molding surface that molds the tread part tread of the tire,
A plurality of recesses are formed on at least a part of the tread surface,
An outer diameter of the recess is 5 to 70 μm, and is more than 0 times and not more than 100 times the distance between the recesses.