JP7279409B2 - pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire provided with a two-dimensional cord on the sidewall portion of the tire.

In recent years, it has been proposed to provide a two-dimensional code in which information is recorded on the sidewall portion of a pneumatic tire (hereinafter simply referred to as a tire). Since the two-dimensional code can contain more information than the one-dimensional code, various information can be contained in the two-dimensional code to manage tires. In particular, it has been proposed to provide a two-dimensional code composed of a pattern of dark and light elements on the tire side surface by imprinting a predetermined pattern of dot holes on the tire side surface (side wall portion) (Patent document 1).

The two-dimensional code, which is formed by imprinting a predetermined pattern of dot holes on the tire side surface, does not disappear unless the tire side surface is worn, so that the tire can be managed effectively.

WO2005/000714

The readability of information recorded in the information recording code may deteriorate depending on the brightness of the surroundings and the way the light is applied. Reading of the information recording code means reading of the information recording code by an information recording code reader, for example, a portable terminal, and deterioration of readability means that the reading is more likely to fail. Therefore, the information recording code is required to have high readability.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pneumatic tire with improved readability compared to information recording codes provided on conventional tires.

One aspect of the present invention is a pneumatic tire,
A side rubber provided on each of the sidewall portions of the pneumatic tire so as to cover the carcass ply of the pneumatic tire from the outside of the tire,
The surface of the side rubber is provided with a two-dimensional code in which a pattern is formed by two types of mutually identifiable shading elements,
The two-dimensional code is
a light portion formed on the side rubber portion to be the light element of the light and dark element and having a surface arithmetic mean roughness Ra of 3.2 μm or less;
a dark portion in which dot holes are engraved in the portion of the side rubber that becomes the dark element of the light and dark element ,
A pair of recesses extending in the tire radial direction are provided in the side rubber portions on both sides of the two-dimensional cord in the tire circumferential direction.

With respect to the recess depth D of the recess from the surface of the bright portion, 0.5 mm < D < 5 mm,
It is preferable that the width W of the recess along the tire circumferential direction satisfies 0.5 mm<W<D.

It is preferable that the depth D of the concave portion exceeds 1 mm, and the hole depth of the dot hole is 0.3 to 1.0 mm.
It is preferable that the two-dimensional cord is positioned inside in the tire radial direction of the tire radial position of the pneumatic tire where the tire maximum width is positioned.

According to the pneumatic tire of the present invention, readability is improved as compared with information recording codes provided on conventional tires.

It is a figure showing an example of composition of a pneumatic tire of one embodiment. (a), (b) is a figure explaining an example of the two-dimensional code of one Embodiment. It is a figure explaining a pair of recessed part. It is a figure explaining a pair of recessed part. It is a figure explaining a pair of convex part of a tire mold. It is a figure explaining the modification of the two-dimensional code of FIG.2(b).

The pneumatic tire of this embodiment will be described in detail below. This embodiment includes various embodiments described later.
In this specification, the tire width direction is a direction parallel to the rotation axis AX of the pneumatic tire. The tire width direction outer side is the side away from the tire equator line CL (see FIG. 1) representing the tire equatorial plane in the tire width direction. Further, the inner side in the tire width direction is the side closer to the tire equator line CL in the tire width direction. The tire circumferential direction is the direction in which the pneumatic tire rotates around the rotation axis AX. The tire radial direction is a direction orthogonal to the rotation axis AX of the pneumatic tire. The tire radial direction outer side refers to the side away from the rotation axis AX. Moreover, the inner side in the tire radial direction refers to the side closer to the rotation axis AX.

The two-dimensional code referred to in this specification is a matrix display type code that has information in two directions, as opposed to a one-dimensional code (bar code) that has information only in the horizontal direction. As a two-dimensional code, for example, QR code (registered trademark), Data Matrix (registered trademark), Maxicode, PDF-417 (registered trademark), 16K code (registered trademark), 49 code (registered trademark), Aztec code (registered trademark) ), SP Code(R), VeriCode(R), and CP Code(R).

(pneumatic tire)
FIG. 1 is a diagram showing an example of the configuration of a pneumatic tire 10 (hereinafter simply referred to as tire 10) according to one embodiment. FIG. 1 shows a profile section on one side in the tire width direction with respect to the tire equator line CL.

The tire 10 includes a tread portion 10T having a tread pattern, a pair of bead portions 10B on both sides in the tire width direction, and a pair of sides provided on both sides of the tread portion 10T and connected to the pair of bead portions 10B and the tread portion 10T. and a wall portion 10S. The tread portion 10T is a portion that contacts the road surface. The sidewall portions 10S are portions provided so as to sandwich the tread portion 10T from both sides in the tire width direction. The bead portion 10B is a portion connected to the sidewall portion 10S and positioned radially inward of the sidewall portion 10S.

The tire 10 has a carcass ply 12, a belt 14, and a bead core 16 as skeleton materials, and a tread rubber 18, a side rubber 20, a bead filler rubber 22, and a rim cushion around these skeleton materials. It mainly has a rubber 24 and an inner liner rubber 26 .

The carcass ply 12 is composed of a carcass ply material in which organic fibers are coated with rubber and wound between a pair of annular bead cores 16 to form a toroidal shape. The carcass ply 12 is wound around the bead core 16 and extends outward in the tire radial direction. A belt 14 composed of two belt members 14a and 14b is provided outside the carcass ply 12 in the tire radial direction. The belt 14 is made of a belt material in which a rubber-coated steel cord is arranged at a predetermined angle, for example, 20 to 30 degrees, with respect to the tire circumferential direction. is longer than the width of the upper belt material 14b in the tire width direction. The steel cords of the two layers of belt materials 14a and 14b extend obliquely in opposite directions with respect to the tire circumferential direction. For this reason, the belt materials 14a and 14b are interlaced layers, which suppress the expansion of the carcass ply 12 due to the filled air pressure.

A tread rubber 18 is provided outside the belt 14 in the tire radial direction, and side rubbers 20 are connected to both ends of the tread rubber 18 to form sidewall portions 10S. A rim cushion rubber 24 is provided at the inner end in the tire radial direction of the side rubber 20 and contacts the rim on which the tire 10 is mounted. On the outside of the bead core 16 in the tire radial direction, a bead is sandwiched between a portion of the carcass ply 12 before being wound around the bead core 16 and a portion of the carcass ply 12 after being wound around the bead core 16. A filler rubber 22 is provided. The bead filler rubber 22 extends outward in the tire radial direction from the bead core 16 side along the carcass ply 12 . An inner liner rubber 26 is provided on the inner surface of the tire 10 facing the air-filled tire cavity area surrounded by the tire 10 and the rim.
In addition, between the belt material 14b and the tread rubber 18, a three-layer belt cover 30 made of organic fibers covered with rubber is provided to cover the belt 14 from the outside in the tire radial direction. The belt cover 30 may be provided as required, and is not essential. The number of layers of the belt cover 30 is also not limited to three, and may be one or two.
A two-dimensional cord 40 is provided on the surface of the sidewall portion 10S of the tire 10 as described above. In FIG. 1, the arrangement position of the two-dimensional code 40 is indicated by a thick line.

(Sidewall part 10S, two-dimensional code 40)
FIG. 2(a) is a diagram illustrating an example of the two-dimensional code 40 of one embodiment provided on the surface of the sidewall portion 10S of the tire 10. FIG. FIG. 2B is a diagram illustrating an example of the two-dimensional code 40. As shown in FIG.
A two-dimensional code 40 is imprinted on the surface of the side rubber 20 of one of the sidewall portions 10S by irradiating a laser beam. The two-dimensional code 40 is formed by forming a dot pattern with two kinds of dark and light elements formed so as to be mutually identifiable by unevenness of the surface. The two-dimensional code 40 is formed by converging a laser beam on the surface of the sidewall portion 10S, concentrating light energy, locally heating the side rubber 20 and sublimating it, and imprinting a plurality of minute dot holes 40a on the surface. pattern. As shown in FIG. 2(b), the dot holes 40a forming the dot pattern have a cross section that gradually decreases along the depth direction. The dot holes 40a are circular or square holes on the tread surface. In the case of a perfect circle, the diameter is 0.1 to 1.0 mm, and the hole depth D is 0.3 to 1.0 mm. is.

In the two-dimensional code 40, one dot hole is marked by a laser beam in the unit cell area of the dark area among the unit cells that divide the dark and light elements of the two-dimensional code. No dot holes are provided in the unit cell area of the light area among the unit cells. That is, the two-dimensional code 40 corresponds to a plurality of rectangular unit cell areas of the same size divided into a lattice, and dot holes are arranged so that each dot hole forms one unit cell area with a dark and light element. has an imprinted configuration. In FIG. 2(a), the dark area of the unit cell area is indicated by a black area.

The two-dimensional code 40 shown in FIG. 2(a) is a QR code (registered trademark) and includes a dot pattern area 42 in which a dot pattern is formed with two types of shading elements. In the dot pattern area 42, the dot holes 40a are formed in the bright portions 46 formed in the portion of the side rubber 20 that is the light element of the shading element, and the dot holes 40a are formed in the portion of the side rubber 20 that is the dark element of the shading element as described above. and a dark area 48 . Around the dot pattern area 42, a blank area 44 composed of light elements surrounded by light elements among the density elements is provided. (In FIG. 2(a), a frame line is shown in order to clarify the outer edge of the blank area 44). The blank area 44 is configured similarly to the bright portion 46 of the dot pattern area 42 . The width w of the blank area 44 is preferably 4 to 5 times the dimension size of the unit cell area in the dot pattern area 42, for example. For example, blank area 44 is preferably 15-25% of the width of dot pattern area 42 .
Since the two-dimensional code 40 shown in FIG. 2(a) is a QR code (registered trademark), the dot pattern area 42 includes a data cell area 42a displaying the data cells of the QR code (registered trademark) and a cutout symbol. and a clipped symbol area 42b.

In the example shown in FIG. 2B, the dot hole 40a forming the dot pattern of the two-dimensional code 40 has a hole cross section that gradually becomes smaller along the depth direction and forms a sharp angular shape at the hole bottom. there is However, the hole bottom need not have a sharp angular shape, and may have a planar shape, for example.

In the present embodiment, the bright portion 46 has a surface arithmetic mean roughness Ra of 3.2 μm or less. Since the surface of the side rubber 20 having a small arithmetic mean roughness Ra is a specular surface, the light reflectance is high. Therefore, the bright portion 46 of the two-dimensional code 40 looks bright. On the other hand, the dark portion 48 is a portion in which the dot holes 40a are formed, and looks dark due to shadows formed in the dot holes 40a. Since the two-dimensional code 40 including the bright portion 46 and the dark portion 48 has a large contrast between the bright portion 46 and the dark portion 48, the initial readability of the two-dimensional code 40 is improved. The above surface of the bright portion 48 means the flat surface of the side rubber 20 that faces the outside in the tire width direction, more specifically, the direction perpendicular to the extending direction of the side rubber 20 along the side surface of the tire 10 .
In addition, since the bright portion 46 has a small arithmetic mean roughness Ra and a small surface area, it is less likely to deteriorate due to irradiation with ultraviolet rays than when the arithmetic mean roughness Ra is large. The occurrence and propagation of cracks in is suppressed. Therefore, it is easy to distinguish the light and dark elements, and readability after long-term use is improved.

In this specification, arithmetic mean roughness Ra means arithmetic mean roughness Ra measured based on JIS B0601. Specifically, the arithmetic mean roughness Ra is obtained using a roughness curve measured using a roughness measuring machine and a high-pass filter with a cutoff value λc.

The arithmetic mean roughness Ra of the bright portion 46 is preferably 2.4 μm or less, more preferably 1.6 μm, from the viewpoint of improving the readability of the two-dimensional code 40 by increasing the reflectance on the surface of the bright portion 46. Below, it is particularly preferably 0.8 μm or less.

According to one embodiment, the surface of the bright portion 46 is preferably a surface (mold transfer surface) onto which the shape of the mirror-finished wall surface of the tire mold is transferred. An arithmetic average roughness Ra of 3.2 μm or less on the surface of the bright portion 46 is obtained, for example, by such a mold transfer surface. The wall surface of the tire mold means the surface of the inner wall of the tire mold with which the unvulcanized rubber that becomes the side rubber 20 contacts during tire molding. Mirror finishing can be performed by polishing the wall surface of the tire mold by a conventionally known method. The range to be mirror-finished includes at least the region of the side rubber 20 where the two-dimensional code 40 is formed, and is preferably a region wider than the region where the two-dimensional code 40 is formed (e.g. 130% area). That is, the two-dimensional code 40 can be produced efficiently by preliminarily forming the entire side rubber 20 portion on which the two-dimensional code 40 is to be formed, including the portion of the side rubber 20 that becomes the dark portion 48, as a mold transfer surface. be able to. The dot holes formed in the dark portion 48 can be provided on the surface of the side rubber 20, which is the mold transfer surface. The arithmetic mean roughness Ra of the mirror-finished tire mold wall is, for example, 2.4 μm or less, preferably 1.6 μm or less, and more preferably 0.8 μm or less.

Further, according to one embodiment, the surface of the light portion 46 is a surface (fluid transfer surface) formed by vulcanizing the surface of unvulcanized rubber that will be the side rubber 20 in contact with gas or liquid. preferable. Specifically, the surface of the bright portion 46 is formed by performing vulcanization in a state in which a gas or liquid is interposed between the surface of the unvulcanized rubber that becomes the side rubber 20 and the wall surface of the tire mold. can get. Since the surface of such a bright portion 46 is a smooth surface and has a high light reflectance, readability of the two-dimensional code 40 is improved. In addition, air is used for gas, for example. For example, oil is used as the liquid. The method of making the fluid transfer surface is described in greater detail below. The arithmetic average roughness Ra of the wall surface of the tire mold, which is the fluid transfer surface, is, for example, 2.4 μm or less, preferably 1.6 μm or less, and more preferably 0.8 μm or less.

According to one embodiment, as shown in FIGS. 3 and 4 , a pair of grooves extending in the tire radial direction are recessed with respect to the surface of the bright portion 46 and are provided in the side rubber 20 on both sides of the two-dimensional cord 40 in the tire circumferential direction. It is preferable to have a recess 50 of 3 and 4 are diagrams illustrating an example of a pair of recesses 50, and FIG. 3 shows only one recess 50. FIG. The recessed portion 50 shown in FIG. 4 extends continuously along the tire radial direction and has a groove-like shape. Note that in FIG. 4, the dot pattern area 42 of the two-dimensional code 40 shows only the outline. Such a concave portion 50 is formed by transferring the shape of a pair of convex portions 64 provided on the wall surface of the tire mold 60 to the side rubber 20 as shown in FIG.

Here, a method of molding the tire 10 using the tire mold 60 shown in FIG. 5 will be described. FIG. 5 is a diagram illustrating a pair of protrusions 64 of the tire mold 60. As shown in FIG. The pair of projections 64 are formed from the tire circumferential direction both sides of the wall surface 62 for molding the unvulcanized rubber that will become the side rubber 20 , where the side rubber 20 portion on which the two-dimensional cord 40 is formed contacts. , project in the normal direction of the wall surface 62 and extend continuously in the radial direction of the tire mold. The wall surface 62 has a curved surface corresponding to the curved shape of the surface of the side rubber 20 . Therefore, when the tire mold 60 is arranged so that the wall surface 62 faces upward, fluid such as oil can be accumulated in the space between the pair of projections 64 . When the unvulcanized rubber flows into the wall surface 62 containing the fluid, the fluid intervenes between the wall surface 62 and the unvulcanized rubber, and vulcanization is performed in this state to form a fluid transfer surface. . In this way, the entire area of the side rubber 20 where the two-dimensional code 40 is to be formed, including the portion of the side rubber 20 that becomes the dark portion 48, is preliminarily used as a fluid transfer surface, so that the two-dimensional code 40 can be produced efficiently. It can be carried out. The dot holes formed in the dark portion 48 can be provided on the surface of the side rubber 20, which is the fluid transfer surface.

By molding the tire 10 in this way, the wall surface 62 and the unvulcanized rubber are more likely to be separated than when molding is performed using a tire mold that does not have the pair of protrusions 64. A fluid layer is stably interposed between them, and a fluid transfer surface can be formed on the surface of the side rubber 20 . Further, by molding the tire 10 as described above, the tire 10 in which the fluid transfer surface is formed on the surface of the side rubber 20 can be repeatedly manufactured regardless of the state of the surface of the wall surface 62. If the surface of the wall surface 62 is dirty, even if the arithmetic mean roughness Ra of the wall surface 62 is small, it will not be accurately transferred to the tire 10 when unvulcanized rubber is molded without the interposition of a fluid. The arithmetic mean roughness Ra of 46 becomes large.

In molding using the tire mold 60 described above, it is also easy to interpose a gas such as air between the unvulcanized tire and the wall surface 62 instead of the fluid. When the unvulcanized tire flows into the tire mold 60, the flow of the rubber is partially blocked by the pair of protrusions 64, and the unvulcanized rubber flows between the pair of protrusions 64 at a delayed timing. This allows air to accumulate between the unvulcanized rubber and the wall surface 62 . Further, for example, after the unvulcanized rubber has flowed into the tire mold, the unvulcanized rubber positioned between the pair of protrusions 64 and the wall surface 62 are interposed through holes (not shown) provided in the mold 60 . It can also be filled with gas.

According to one embodiment, the tire 10 satisfies 0.5 mm<D<5 mm for the recess depth D of the recess 50 from the surface of the bright portion 46, and the width W of the recess along the tire circumferential direction is 0. .5mm<W<D is preferably satisfied. The concave portion 50 having such dimensions satisfies 0.5 mm<H<5 mm for the height H of the convex portion 64 from the surface of the wall surface 62, and 0.5 mm<0.5 mm for the width W of the concave portion along the tire circumferential direction. It can be produced using a tire mold provided with a pair of protrusions 64 that satisfy W<H. The height H is the maximum height of the convex portion 64 in the example shown in FIG.
If the height H of the protrusions 64 is less than 0.5 mm, it is difficult to obtain the effect of retaining the layer of gas or liquid between the pair of protrusions 64 . If the height H of the protrusion 64 exceeds 5 mm, cracks generated from the bottom of the recess 50 of the tire 10 may grow and reach the carcass ply 12 . Therefore, the durability of the tire 10 may deteriorate. In addition, foreign matter such as mud tends to clog the recessed portion 50 that has been transferred, and the side rubber 20 on which the two-dimensional code 40 is formed may be deformed, degrading readability.
Further, if the width W of the protrusion 64 is less than 0.5 mm, the metal material forming the protrusion 64 is likely to deform. Further, when the recessed portion 50 is deformed, the stress generated at the bottom (groove bottom) of the recessed portion 50 is not dispersed and tends to concentrate locally, and cracks are likely to occur from the bottom of the recessed portion 50 of the tire 10 . If the width W of the protrusion 64 exceeds the height of the protrusion 64, the effect obtained by the large width W cannot be increased.

In the tire 10, the recess depth D of the recess 50 preferably satisfies 1 mm<D<4 mm, and the width W satisfies 1 mm<W<0.8D. Further, the tire 10 preferably satisfies 1 mm<D<4 mm for the recess depth D of the protrusion 64 and 1 mm<W<0.8D for the width W of the protrusion 64 .

According to one embodiment, as shown in FIG. 1, the two-dimensional cord 40 is preferably located radially inward of the tire radial position where the tire maximum width is located. Since the hard rubber which becomes the bead filler rubber 22 is arranged in the portion of the raw tire which becomes the bead portion 10B, the raw rubber is hardly swelled when pressed against the tire mold from the inside of the tire 10 by the bladder. Therefore, the portion of the unvulcanized rubber that becomes the side rubber 20 near the bead portion 10B flows closer to the wall surface of the tire mold later than the portion of the surrounding unvulcanized rubber. Air tends to accumulate between the wall surface of the rubber and the unvulcanized rubber. Thus, it is easy to obtain a fluid transfer surface inside the tire radial direction position of the tire maximum width.

(Modification)
A modification of the tire 10 will be described with reference to FIG. FIG. 6 is a diagram explaining a modification of the two-dimensional code of FIG. 2(b).
Unlike the tire 10 described above, the tire according to the modification does not have dot holes in the dark portions 48 of the two-dimensional code 40, but instead has a surface arithmetic mean roughness Ra larger than that of the bright portions 46. ing. In the tire 10 of the present embodiment, as described above, the arithmetic mean roughness Ra of the surface of the bright portion 46 is 3.2 μm or less, and the light reflectance on the surface of the bright portion 46 is high. The dark portion 48 that can be distinguished from the bright portion 46 can be easily formed by adjusting the arithmetic mean roughness Ra without forming the dark portion. In this modification, the dark portion 48 has a surface arithmetic mean roughness Ra larger than that of the bright portion 46 , and the light reflectance on the surface is lower than that of the bright portion 46 . Since the two-dimensional code 40 including the bright portion 46 and the dark portion 48 has a large contrast between the bright portion 46 and the dark portion 48, the initial readability of the two-dimensional code 40 is improved. Thus, in this modification, since it is not necessary to provide deep holes such as dot holes, the occurrence and propagation of cracks on the surface of the two-dimensional code 40 are suppressed, and the dark and light elements can be easily distinguished. readability is improved.

According to one embodiment, the surface of the dark portion 48 is preferably the roughened surface of the side rubber 20 (roughened surface). The surface roughening can be performed by a known method such as blasting or processing by laser beam irradiation (laser processing). When the surface is roughened by blasting, for example, the projection material is projected while masking the area of the surface of the side rubber 20 excluding the surface of the side rubber 20 that will be the dark portion 48 . The roughened surface of the side rubber 20 can also be obtained by transferring the roughened wall surface of the tire mold to the surface of the side rubber 20 . Such roughening treatment of the wall surface of the tire mold can also be performed by using a method such as blasting or laser processing. For the surface roughening, for example, as described above, the entire portion of the side rubber 20 on which the two-dimensional code 40 is formed is previously formed as a mold transfer surface or a fluid transfer surface, and then the side rubber 20 that becomes the dark portion 48 is roughened. The two-dimensional code 40 can be produced efficiently by roughening only the region of .

According to one embodiment, the difference in arithmetic mean roughness Ra between the surface of the bright portion 46 and the surface of the dark portion 48 is preferably 3 μm or more. Due to such a difference in arithmetic mean roughness Ra, the contrast between the bright portion 46 and the dark portion 48 is further increased, and the readability of the two-dimensional code 40 is improved. The difference in arithmetic mean roughness Ra is preferably 5 μm or more, more preferably 7 μm or more.

According to one embodiment, the surface arithmetic mean roughness Ra of the dark portion 48 is preferably 6.4 μm or more. Since the dark portion 48 having such an arithmetic mean roughness Ra has a large difference in light reflectance compared to the bright portion 46, the contrast between the bright portion 46 and the dark portion 48 is even greater, and the readability of the two-dimensional code 40 is improved. improves. The arithmetic mean roughness Ra of the surface of the dark portion 48 is preferably 7.2 μm or more, more preferably 8.0 μm or more.

(Comparative example, example)
In order to confirm the effect of the above-described embodiment, a tire 10 (tire size: 195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195/195) 65R15 91H) were prepared, and the readability test of the two-dimensional code 40 of the tire 10 was conducted. The tire configuration of the tire 10 was the configuration shown in FIG.
Table 1 shows specifications of the tire 10 in which dot holes are formed in dark areas. The dot holes 40a of the two-dimensional code 40 are circular holes with an inner diameter of 0.5 mm. The size of the QR code (registered trademark) was 15 mm×15 mm. Table 2 shows the specifications of the tire 10 in which dot holes are not formed in dark areas and the arithmetic mean roughness Ra is adjusted.
Specifically, 10 tires 10 were prepared for each of the examples and the comparative examples, and the two-dimensional code 40 was read by the portable terminal while variously changing the illumination light. The ratio of the number of correct readings to the number of readings of the two-dimensional code 40 was taken as the reading rate. The initial reading rate was based on Comparative Example 1 (the reading rate of Comparative Example 1 was taken as an index of 100), and the reading rates of Examples 1 to 7 were indexed. In addition, the reading rates of Examples 11 to 14 were indexed using Comparative Example 2 as a reference (the reading rate of Comparative Example 2 was set to 100). A higher index means an improved reading rate.

Specifications and evaluation results are shown in Tables 1 and 2 below.
In the table, the column of "dark area" indicates the form of the surface of the dark area, "dot hole" indicates that the dark area was made into a dot hole, and "rough surface" indicates the surface of the dark area that has been roughened by blasting. indicates that
The column of "bright part preparation method" indicates the method of preparing the surface of the bright part, "non-mirror surface" indicates that it was prepared using the roughened wall surface of the tire mold, and "mirror surface" indicates that the tire "Air layer" indicates that air was interposed (created an air layer) between the unvulcanized rubber and the tire mold.
“Presence/absence of concave portion” indicates whether or not a pair of concave portions is formed on both sides of the two-dimensional cord in the tire circumferential direction. That is, it indicates whether or not the concave portion is formed using a tire mold having a pair of convex portions on the wall surface.
It should be noted that a negative value for the "concave depth D" indicates that a convex portion was provided instead of the concave portion. That is, it indicates whether or not the protrusion is formed using a tire mold having a pair of groove-shaped recesses on the wall surface.
In Table 2, "difference in roughness" indicates the difference in arithmetic mean roughness Ra between the surface of the bright portion and the surface of the dark portion.

From the comparison between Comparative Example 1 and Examples 1 to 7, when dot holes are formed in the dark portion, the initial readability is improved by the surface arithmetic mean roughness Ra of the bright portion being 3.2 μm or less. Recognize.
From the comparison between Example 4 and Example 5, when the concave portion is formed, that is, by creating an air layer using a tire mold provided with the convex portion, the arithmetic mean roughness Ra of the bright portion is reduced, It can be seen that the initial readability is improved.
From the comparison of Example 5 and Example 6, it can be seen that by satisfying 0.5 mm<D<5 mm and 0.5 mm<W<D with respect to the recess depth D and width W of the recess, that is, such a recess It can be seen that by forming an air layer using a convex portion having dimensions such that .theta.

From the comparison between Comparative Example 2 and Examples 11 to 14, when the arithmetic average roughness Ra of the surface of the dark area is made larger than that of the bright area, the arithmetic average roughness Ra of the surface of the bright area is 3.2 μm or less. , the initial readability is improved.
From the comparison between Example 11 and Examples 12 to 14, it can be seen that the initial readability is further improved when the difference in arithmetic mean roughness Ra between the surface of the bright portion and the surface of the dark portion is 3 μm or more.

Although the pneumatic tire of the present invention has been described in detail above, the pneumatic tire of the present invention is not limited to the above embodiments or examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course you can.

10 pneumatic tire 10T tread portion 10S sidewall portion 10B bead portion 12 carcass ply 14 belts 14a, 14b belt material 16 bead core 18 tread rubber member 20 side rubber member 22 bead filler rubber member 24 rim cushion rubber member 26 inner liner rubber member 30 belt Cover 40 Two-dimensional code 42 Dot pattern area 42a Data cell area 42b Symbol area 44 Blank area 46 Bright part 48 Dark part 50 Concave part 60 Tire mold 62 Wall surface 64 Convex part

Claims (4)

A pneumatic tire,
A side rubber provided on each of the sidewall portions of the pneumatic tire so as to cover the carcass ply of the pneumatic tire from the outside of the tire,
The surface of the side rubber is provided with a two-dimensional code in which a pattern is formed by two types of mutually identifiable shading elements,
The two-dimensional code is
a light portion formed on the side rubber portion to be the light element of the light and dark element and having a surface arithmetic mean roughness Ra of 3.2 μm or less;
a dark portion in which dot holes are engraved in the portion of the side rubber that becomes the dark element of the light and dark element ,
A pneumatic tire, wherein a pair of concave portions extending in the tire radial direction are provided in the side rubber portions on both sides of the two-dimensional cord in the tire circumferential direction. With respect to the recess depth D of the recess from the surface of the bright portion, 0.5 mm < D < 5 mm,
The pneumatic tire according to claim 1 , wherein a width W of the recess along the tire circumferential direction satisfies 0.5 mm<W<D. The pneumatic tire according to claim 2, wherein the recess depth D of the recess exceeds 1 mm, and the hole depth of the dot hole is 0.3 to 1.0 mm. The pneumatic tire according to any one of claims 1 to 3 , wherein the two-dimensional cord is positioned inside in the tire radial direction of a tire maximum width position of the pneumatic tire.

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