U.S. patent application number 16/098819 was filed with the patent office on 2019-07-04 for rubber member, tire, and method of manufacturing rubber member.
The applicant listed for this patent is Chitose Institute of Science and Technology, National University Corporation Hokkaido University, Tohoku Techno Arch Co., Ltd., The Yokohama Rubber Co., LTD.. Invention is credited to Toshihiko Arita, Yuji Hirai, Yasutaka Matsuo, Takahiro Okamatsu, Masatsugu Shimomura.
Application Number | 20190202244 16/098819 |
Document ID | / |
Family ID | 60203060 |
Filed Date | 2019-07-04 |
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United States Patent
Application |
20190202244 |
Kind Code |
A1 |
Okamatsu; Takahiro ; et
al. |
July 4, 2019 |
Rubber Member, Tire, and Method of Manufacturing Rubber Member
Abstract
A vehicle tire, as a rubber member, includes, on at least a part
of the surface thereof, a fine ridged/grooved structure formed via
transfer from a mold and having fine ridged/grooved portions
arranged at a constant arrangement pitch, wherein a region in which
the fine ridged/grooved structure is provided is visually
recognizable by a different structural color from the colors of
other regions. The fine ridged/grooved structure is formed on a
sidewall portion of the vehicle tire, and the region in which the
fine ridged/grooved structure is provided is formed in a shape to
display predetermined information.
Inventors: |
Okamatsu; Takahiro;
(Hiratsuka-shi, Kanagawa, JP) ; Shimomura; Masatsugu;
(Chitose-shi, Hokkaido, JP) ; Hirai; Yuji;
(Chitose-shi, Hokkaido, JP) ; Matsuo; Yasutaka;
(Sapporo-shi, Hokkaido, JP) ; Arita; Toshihiko;
(Sendai-shi, Miyagi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Yokohama Rubber Co., LTD.
Chitose Institute of Science and Technology
National University Corporation Hokkaido University
Tohoku Techno Arch Co., Ltd. |
Minato-ku, Tokyo
Chitose-shi, Hokkaido
Sapporo-shi, Hokkaido
Sendai-shi, Miyagi |
|
JP
JP
JP
JP |
|
|
Family ID: |
60203060 |
Appl. No.: |
16/098819 |
Filed: |
May 2, 2017 |
PCT Filed: |
May 2, 2017 |
PCT NO: |
PCT/JP2017/017216 |
371 Date: |
November 2, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 3/04 20130101; C08L
19/00 20130101; C08L 7/00 20130101; B60C 13/00 20130101; C08L 9/00
20130101; B29D 2030/726 20130101; B60C 1/0025 20130101; B29D 30/72
20130101; B29C 59/02 20130101; B60C 1/00 20130101; B60C 13/001
20130101; C08K 3/36 20130101 |
International
Class: |
B60C 13/00 20060101
B60C013/00; B29D 30/72 20060101 B29D030/72; B60C 1/00 20060101
B60C001/00; C08L 7/00 20060101 C08L007/00; C08L 19/00 20060101
C08L019/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2016 |
JP |
2016-092388 |
Claims
1. A rubber member comprising: a fine ridged/grooved structure on
at least a part of a surface of the rubber member, the fine
ridged/grooved structure formed via transfer from a mold and having
fine ridged/grooved portions arranged at a constant arrangement
pitch; a region in which the fine ridged/grooved structure is
provided being visually recognizable by a structural color
different from colors of other regions.
2. The rubber member according to claim 1, wherein the arrangement
pitch or ridge/groove height of the fine ridged/grooved portions is
determined based on a wavelength of visible light, the wavelength
corresponding to a color visually recognizable as the structural
color.
3. The rubber member according to claim 1, wherein the arrangement
pitch or ridge/groove height of the fine ridged/grooved portions is
equal to or smaller than 650 nm.
4. A tire made of a rubber member described in claim 1.
5. The tire according to claim 4, wherein the fine ridged/grooved
structure is formed on a sidewall portion, and the region in which
the fine ridged/grooved structure is provided is formed in a shape
to display predetermined information.
6. The tire according to claim 5, wherein the sidewall portion
contains a diene rubber, a carbon black, and a silica, and the
diene rubber contains from 30 to 70 mass % of natural rubber and/or
isoprene rubber, a nitrogen adsorption specific surface area of the
carbon black is from 20 to 60 m.sup.2/g, a content of the carbon
black is from 5 to 45 parts by mass per 100 parts by mass of the
diene rubber, a content of the silica is from 15 to 55 parts by
mass per 100 parts by mass of the diene rubber, and a total content
of the carbon black and the silica is from 30 to 60 parts by mass
per 100 parts by mass of the diene rubber.
7. A method of manufacturing the rubber member described in claim
1, the method comprising: forming a mask on which pattern
structures are arranged at the constant pitch; arranging the mask
on a substrate made of a metal or a semiconductor material and
etching the substrate; and adhering unvulcanized rubber to the
substrate, vulcanizing the unvulcanized rubber to form vulcanized
rubber, and transferring the fine ridged/grooved structure to a
surface of the vulcanized rubber.
8. The method of manufacturing the rubber member according to claim
7, further comprising determining the arrangement pitch of the fine
ridged/grooved portions based on a wavelength of visible light, the
wavelength corresponding to the color visually recognizable as the
structural color, wherein in the forming the mask, the pitch of the
pattern structures is determined based on the arrangement pitch
determined in the determining the arrangement pitch.
9. The method of manufacturing the rubber member according to claim
7, further comprising determining a ridge/groove height of the fine
ridged/grooved portions based on a wavelength of visible light, the
wavelength corresponding to the color visually recognizable as the
structural color, wherein in the etching, an etching time of the
substrate is appropriately controlled to match the ridge/groove
height of the ridged/grooved portions with the ridge/groove height
determined in the determining the ridge/groove height.
10. The rubber member according to claim 2, wherein the arrangement
pitch or ridge/groove height of the fine ridged/grooved portions is
equal to or smaller than 650 nm.
11. A tire made of a rubber member described in claim 10.
12. The tire according to claim 11, wherein the fine ridged/grooved
structure is formed on a sidewall portion, and the region in which
the fine ridged/grooved structure is provided is formed in a shape
to display predetermined information.
13. The tire according to claim 12, wherein the sidewall portion
contains a diene rubber, a carbon black, and a silica, and the
diene rubber contains from 30 to 70 mass % of natural rubber and/or
isoprene rubber, a nitrogen adsorption specific surface area of the
carbon black is from 20 to 60 m.sup.2/g, a content of the carbon
black is from 5 to 45 parts by mass per 100 parts by mass of the
diene rubber, a content of the silica is from 15 to 55 parts by
mass per 100 parts by mass of the diene rubber, and a total content
of the carbon black and the silica is from 30 to 60 parts by mass
per 100 parts by mass of the diene rubber.
14. A method of manufacturing the rubber member described in claim
10, the method comprising: forming a mask on which pattern
structures are arranged at the constant pitch; arranging the mask
on a substrate made of a metal or a semiconductor material and
etching the substrate; and adhering unvulcanized rubber to the
substrate, vulcanizing the unvulcanized rubber, and transferring
the fine ridged/grooved structure to a surface of the vulcanized
rubber.
15. The method of manufacturing the rubber member according to
claim 14, further comprising determining the arrangement pitch of
the fine ridged/grooved portions based on a wavelength of visible
light, the wavelength corresponding to the color visually
recognizable as the structural color, wherein in the forming the
mask, the pitch of the pattern structures is determined based on
the arrangement pitch determined in the determining the arrangement
pitch.
16. The method of manufacturing the rubber member according to
claim 14, further comprising determining the ridge/groove height of
the fine ridged/grooved portions based on a wavelength of visible
light, the wavelength corresponding to the color visually
recognizable as the structural color, wherein in the etching, an
etching time of the substrate is appropriately controlled to match
the ridge/groove height of the ridged/grooved portions with the
ridge/groove height determined in the determining the ridge/groove
height.
Description
TECHNICAL FIELD
[0001] The present technology relates to a rubber member, and a
tire, which have a region that produce a color via a structural
color, and a method of manufacturing the rubber member.
BACKGROUND ART
[0002] In the related art, to impart information such as
alphanumerics and marks to the surface of a rubber product such as
a tire, ink has been deposited to the rubber surface by means of an
inkjet printer, to print the information thereon.
[0003] Alternatively, a structure color produced by a fine
structure that is equal to or smaller than a light wavelength has
been known and applied to various fields.
[0004] For example, Japan Unexamined Patent Publication No.
2009-192676 discloses a color filter that produces structural
colors. Japan Patent No. 4925025 discloses the technique of
calculating a distortion of an object by measuring a change in
produced structural colors (wavelength change). In Japan Unexamined
Patent Publication No. 2009-192676, the fine structure that
produces the structural colors is formed by stamping, and in Japan
Patent No. 4925025, the structural color is produced by
periodically arranging microparticles on the surface of an elastic
body.
[0005] In a case where information is printed on a tire by the use
of an inkjet printer as in the above-described related art, the ink
is gradually peeled off from the rubber surface due to expansion
and contraction (deflection) of the rubber during driving. Thus, it
is difficult to maintain the printed information to be visually
recognizable for an extended period of time.
[0006] As described above, the structural color has been applied to
various field. However, the method of forming the fine structure
that produces the structural color by stamping and the method of
laminating a plurality of layers to produce the structural color,
as described in Japan Unexamined Patent Publication No.
2009-192676, are applied to products having a thin-film structure,
such as a color filter. Additionally, such methods often serve to
produce the structural color by utilizing transmitted light
(diffracted light) and therefore, cannot be directly applied to a
less transparent rubber member such as a tire.
[0007] Further, the method of arranging microparticles to produce
the structural color as described in Japan Patent No. 4925025
cannot be easily applied to members requiring heating that may
cause deformation of the members, such as vulcanization in the tire
manufacturing process.
SUMMARY
[0008] The present technology imparts information that will be
visually recognizable for an extended period of time on the surface
of the rubber member.
[0009] A rubber member according to the technology includes a fine
ridged/grooved structure on at least a part of the surface of the
rubber member, the fine ridged/grooved structure formed via
transfer from a mold and having fine ridged/grooved portions
arranged at a constant arrangement pitch; a region in which the
fine ridged/grooved structure is provided is visually recognizable
by a different structural color from the colors of other
regions.
[0010] In the rubber member according to a further aspect of the
technology, the arrangement pitch or ridge/groove height of the
fine ridged/grooved portions is determined based on a wavelength of
visible light, the wavelength corresponding to the color visually
recognizable as the structural color.
[0011] In the rubber member according to a further aspect of the
technology, the arrangement pitch or ridge/groove height of the
fine ridged/grooved portions is equal to or smaller than 650
nm.
[0012] A tire is made of a rubber member according to a further
aspect of the technology.
[0013] In the tire, the fine ridged/grooved structure is formed on
a sidewall portion, and the region in which the fine ridged/grooved
structure is provided is formed in a shape to display predetermined
information.
[0014] In the tire, the sidewall portion contains a diene rubber, a
carbon black, and a silica, the diene rubber contains from 30 to 70
mass % of natural rubber and/or isoprene rubber, a nitrogen
adsorption specific surface area of the carbon black is from 20 to
60 m.sup.2/g, a content of the carbon black is from 5 to 45 parts
by mass per 100 parts by mass of the diene rubber, a content of the
silica is from 15 to 55 parts by mass per 100 parts by mass of the
diene rubber, and a total content of the carbon black and the
silica is from 30 to 60 parts by mass per 100 parts by mass of the
diene rubber.
[0015] A method of manufacturing a rubber member according to the
technology includes: forming a mask on which pattern structures are
arranged at the constant pitch; arranging the mask on a substrate
made of a metal or a semiconductor material and etching the
substrate; and adhering unvulcanized rubber to the substrate,
vulcanizing the unvulcanized rubber, and transferring the fine
ridged/grooved structure to the surface of the vulcanized
rubber.
[0016] The method of manufacturing the rubber member according to a
further aspect of the technology further includes determining the
arrangement pitch of the fine ridged/grooved portions based on a
wavelength of visible light, the wavelength corresponding to the
color visually recognizable as the structural color, and in the
forming the mask, the pitch of the pattern structures is determined
based on the arrangement pitch determined in the determining the
arrangement pitch.
[0017] The method of manufacturing the rubber member according to a
further aspect of the technology further includes determining the
ridge/groove height of the fine ridged/grooved portions based on a
wavelength of visible light, the wavelength corresponding to the
color visually recognizable as the structural color, and in the
etching, an etching time of the substrate is appropriately
controlled to match the ridge/groove height of the ridged/grooved
portions with the ridge/groove height determined in the determining
the ridge/groove height.
[0018] According to the technology, in at least a part of the
rubber member, a structural color exhibits a color that is
different from the colors of other regions. Thus, the durability of
an indicator on the rubber surface is advantageously improved
compared to a case where the indicator is drawn using ink or the
like.
[0019] According to the technology, information may be indicated in
any color on the surface of the rubber member by appropriately
modifying the arrangement pitch or ridge/groove height of the fine
ridged/grooved portions.
[0020] According to the technology, information may be displayed in
any color including red.
[0021] According to the technology, information may be indicated in
the structural color on the tire surface. Thus, the indicator is
advantageously employed with high durability against wear caused by
the use of the tire.
[0022] According to the technology, information may be
advantageously indicated in the structural color with high
durability on the sidewall portion.
[0023] The sidewall portion is easily visually recognizable in the
tire from outside and has conventionally been used to indicate
various information about the tire.
[0024] According to the technology, information may be
advantageously indicated in the structural color on the surface of
rubber having high resistance to deformation, which is suitable for
the sidewall portion.
[0025] According to the technology, in at least a part of the
rubber member, a region can be formed, in which a structural color
exhibits a color that is different from the colors of other
regions. Thus, the durability of the indicator on the rubber
surface is advantageously improved compared to a case where the
indicator is drawn using ink or the like.
[0026] According to the technology, the arrangement pitch of the
fine ridged/grooved portions may be advantageously set to any
dimension.
[0027] According to the technology, the ridge/groove height of the
fine ridged/grooved portions may be advantageously set to any
dimension.
BRIEF DESCRIPTION OF DRAWINGS
[0028] FIG. 1 is a side view illustrating a vehicle tire 10
according to an embodiment.
[0029] FIGS. 2A and 2B are partial enlarged views of a logo mark
204.
[0030] FIG. 3 is a table showing the results of the durability test
on the present technology and the conventional art.
DETAILED DESCRIPTION
[0031] A rubber member, a tire, and a method of manufacturing the
rubber member according to a preferred embodiment of the present
technology are described in detail below with reference to
accompanying drawings.
[0032] In the present embodiment, an example of application of the
rubber member according to the present technology to a vehicle tire
is described.
[0033] FIG. 1 is a side view illustrating a vehicle tire 10
according to the embodiment of the technology.
[0034] The vehicle tire 10 includes a tread portion 14 having a
tread surface that makes a contact with a road surface, a bead
portion 16 engaged with a wheel (not illustrated), and a sidewall
portion 12 that connects the tread portion 14 to the bead portion
16 and constitutes a tire side surface.
[0035] In the tread portion 14, wear resistance is important, while
in the sidewall portion 12, the resistance to deformation caused by
loads during driving is important. Thus, the composition in the
sidewall portion 12 is different from that of the tread portion
14.
[0036] Describing in more detail, in the present embodiment, the
sidewall portion 12 contains a diene rubber, a carbon black, and a
silica, the diene rubber contains from 30 to 70 mass % of natural
rubber and/or isoprene rubber, a nitrogen adsorption specific
surface area of the carbon black is from 20 to 60 m.sup.2/g, a
content of the carbon black is from 5 to 45 parts by mass per 100
parts by mass of the diene rubber, a content of the silica is from
15 to 55 parts by mass per 100 parts by mass of the diene rubber,
and a total content of carbon black and silica is from 30 to 60
parts by mass per 100 parts by mass of the diene rubber.
[0037] Various information is indicated on the sidewall portion
12.
[0038] Examples of the information indicated on the sidewall
portion 12 include a manufacturer name 202 of the vehicle tire 10,
a logo mark 204, a tire brand name 206, a tire dimension 208, a
uniformity mark 214, and a light point mark 216. Examples of the
information also include a tire serial number and a rotation
direction.
[0039] Among the above-described information, the uniformity mark
214 and the light point mark 216 are imparted using ink or the
like, after the completion (vulcanization) and inspection of
individual tires.
[0040] The manufacturer name 202, the manufacturer logo mark 204,
the tire brand name 206, and the tire dimension 208 are imparted by
transferring ridges/grooves formed on a mold during vulcanization
of the vehicle tire 10.
[0041] The information transferred from the ridges/grooves of the
mold, other than the logo mark 204, has the same color as the whole
vehicle tire 10, and is visually recognizable by the ridges/grooves
on the surface of the sidewall portion 12.
[0042] In contrast, the logo mark 204 is in a different color such
as the manufacturer's corporate color, and visually recognizable
from the color of the vehicle tire 10.
[0043] FIG. 2 are partial enlarged views of the logo mark 204. FIG.
2A is a perspective view, and FIG. 2B is a cross-sectional view
taken along A-A.
[0044] A fine ridged/grooved structure 30 is provided on the entire
region of the logo mark 204.
[0045] The fine ridged/grooved structure 30 is configured such that
fine ridged/grooved portions 34 are arranged on a tire surface 32
at a constant arrangement pitch. The region in which the fine
ridged/grooved structure 30 is provided is visually recognizable
due to a different structural color from other regions.
[0046] The fine ridged/grooved portions described herein refer to
various known structures used to produce the structural color, such
as protrusions and holes. In the present embodiment, they are fine
projections protruding from the tire surface 32 that is a curved
surface (or a flat surface).
[0047] The arrangement pitch described in the present embodiment
refers to a distance between centers of adjacent fine projections,
that is, pitch. As represented by a sign L in FIG. 2B, the pitch
corresponds to a total length of each one of the projections and
each one of the recessed portions along the surface of the rubber
member (tire).
[0048] The constant arrangement pitch described herein refers to
various known pitches used to produce the structural color, and may
be a constant value over the entire fine ridged/grooved structure
30, or may vary continuously or gradually.
[0049] The arrangement pitch or the ridge/groove height of the fine
ridged/grooved portions 34 is determined based on a wavelength of
visible light, which corresponds to the color visually recognizable
as the structural color. In other words, the wavelength
corresponding to the color to be exhibited as the structural color
is selected from a wavelength range of the visible light, and a
specific dimension of the arrangement pitch or the ridge/groove
height of the fine ridged/grooved portions 34 is determined
according to the principle of resonance grating.
[0050] In the present embodiment, the arrangement pitch or the
ridge/groove height of the fine ridged/grooved portions 34 is set
to be equal to or smaller than 650 nm, for example. This is because
the experiments conducted by the present inventors demonstrated
that the structural color is recognizable for the fine
ridged/grooved structure 30 having the arrangement pitch or the
ridge/groove height of 650 nm or less.
[0051] In the present embodiment, the fine ridged/grooved portions
34 include a cylinder extending perpendicularly to the tire surface
32. A top surface 3402 of the cylinder is a perfect circle, the
diameter R of which is about 5 .mu.m. A distance S between the
adjacent cylinders is 1 .mu.m, and the arrangement pitch is about 6
.mu.m. For the sake of convenience, FIG. 2 do not illustrate the
elements in actual ratio.
[0052] Here, the present inventors made a plurality of rubber
members, wherein a height (ridge/groove height) H of each of the
fine ridged/grooved portions 34 from the tire surface 32 is
different for each of the tires, while the arrangement pitch of the
fine ridged/grooved portions 34 as well as the diameter of the
cylindrical fine ridged/grooved portions 34 are fixed to the
constant values. As a result, following structural colors were
visually recognized in decreasing order of recognizable area. The
reason why a plurality of colors are visually recognized is that
the structural color varies depending on a viewing angle.
[0053] Ridge/groove height of 650 nm: red, magenta
[0054] Ridge/groove height of 607 nm: magenta, red, orange
[0055] Ridge/groove height of 577 nm: magenta, orange
[0056] Ridge/groove height of 536 nm: orange, magenta
[0057] Ridge/groove height of 500 nm: yellow, green, orange
[0058] As the ridge/groove height was smaller, the color became
more bluish.
[0059] In this manner, information may be indicated in any color on
the rubber surface by adjusting the arrangement pitch or the
ridge/groove height of the fine ridged/grooved portions 34. For
example, to indicate the logo mark 204 in red, the ridge/groove
height may be set to about 650 nm.
[0060] Next, a method of manufacturing the rubber member producing
the structural color will be explained.
[0061] The below-described method of manufacturing the rubber
member includes a step of forming a mold having fine pattern
structures (step 1 and step 2: mold forming step) and a step of
adhering unvulcanized rubber to the mold, vulcanizing the
unvulcanized rubber, and transferring a fine ridged/grooved
structure to the rubber surface (step 3: transferring step).
[0062] Prior to the following steps, the color of the structural
color to be formed on the rubber member is determined, and the
arrangement pitch or the ridge/groove height of the fine
ridged/grooved portions is determined based on the wavelength of
visible light, which corresponds to the determined color (color
visually recognizable as the structural color on the rubber member)
(an arrangement pitch determining step or a ridge/groove
determining step).
[0063] (Step 1) A mask on which pattern structures are arranged at
a constant pitch is formed to form the fine ridged/grooved
structure 30 on the rubber surface (mask forming step).
[0064] First, a chromium (Cr) film of about 80 nm is formed on a
mask forming substrate (silicon substrate) using a sputtering
device. Next, a positive-type electron beam resist is coated on the
chromium film by spin-coating (3 seconds at 300 rpm followed by 60
seconds at 4000 rpm). Then, the substrate coated with the electron
beam resist is pre-baked for 3 minutes on a hot plate at
150.degree. C., and is subjected to exposure and patterning by an
electron beam lithographic device. After that, the substrate is
immersed in a developing solution for 60 seconds to be developed.
In a case where the arrangement pitch of the fine ridged/grooved
portions is determined based on the wavelength of visible light
corresponding to the color visually recognized as the structural
color, that is, the arrangement pitch of the fine ridged/grooved
portions is used as a parameter for determining the structural
color being produced, the arrangement pitch of the pattern
structures in the patterning is determined based on the arrangement
pitch determined in the arrangement pitch determining step. After
development, the substrate is immersed in a mixed-acid chromium
etching solution for about 60 seconds to selectively dissolve off
the exposed Cr, thereby making a mask (photo mask).
[0065] (Step 2) A mask is placed on a substrate made of a metal or
semiconductor material, and the substrate is etched (etching
step).
[0066] In the present embodiment, a single-crystal silicon
substrate is used as the above-mentioned substrate. The substrate
is cleaned with ultrasonic cleaning for 5 minutes in acetone and
methanol in this order, and a positive photoresist is coated on the
substrate by spin-coating (3 seconds at 300 rpm and then, 60
seconds at 5000 rpm). Next, the spin-coated substrate is pre-baked
on a hot plate at 95.degree. C. for 90 seconds. The pre-baking
evaporates off an organic solvent present in the resist and thus
can improve the resist adhesion to the substrate. Subsequently, the
substrate coated with the photoresist is exposed using a mask
aligner and the photo mask manufactured in the step 1, and is
immersed in a developing solution to dissolve off the exposed
section for patterning.
[0067] After patterning, the substrate is etched using a dry
etching device (passivation gas: C.sub.4F.sub.8, 80 sccm, etching
gas: SF.sub.6, 130 sccm, Bosch process) to manufacture a mold
(silicon mold). In a case where the ridge/groove height of the fine
ridged/grooved portions is determined based on the wavelength of
visible light corresponding to the color visually recognizable as
the structural color, that is, the ridge/groove height of the fine
ridged/grooved portions is used as a parameter for determining the
reproduction of the structural color, the ridge/groove height of
the ridge/groove portions can be matched with the ridge/groove
height determined in the ridge/groove height determining step by
appropriately controlling an etching time of the substrate.
[0068] In the above-mentioned step 1 and step 2 (mold forming
step), the mold having the fine ridged/grooved structure is
manufactured by photolithography. However, the method of
manufacturing the rubber member according to the present technology
is not limited to this, and may be various known methods.
[0069] (Step 3) Unvulcanized rubber was adhered to the etched
substrate (mold), the unvulcanized rubber is vulcanized, and the
fine ridged/grooved structure is transferred to the rubber surface
(transferring step).
[0070] Unvulcanized rubber is placed on a silicon mold, is softened
at 80.degree. C. for 10 minutes and then, is pressed and vulcanized
at 160.degree. C. for 10 minutes.
[0071] After vulcanization, the vulcanized rubber is peeled off
from the silicon mold, and the transfer of the fine ridged/grooved
structure to the rubber surface is confirmed. The region in which
the fine ridged/grooved structure is formed is visually
recognizable due to being colored differently from the other
regions (flat regions) on the rubber surface, that is, the
structural color of the fine ridged/grooved structure.
[0072] A durability test is performed on the logo mark 204 thus
formed in the structural color, and a logo mark printed using an
inkjet printer according to the conventional art. Specifically,
surfaces (rubber surfaces) of the logo marks thus formed are rubbed
100 times with a cotton cloth, and the surface state and color
change are visually observed.
[0073] FIG. 3 shows results of the durability test. The table in
FIG. 3 shows a sample number, a color producing method, a
ridge/groove height, a visually recognized color (color
production), and a durability test result. In columns of the
durability test results, an unchanged sample in terms of the
surface state and color is designated as "Pass", and a decolorized
sample is designated as "Fail".
[0074] As illustrated in FIG. 3, after the durability test, the
logo mark printed using the inkjet printer (Comparative Example 2)
can not be visually recognized due to peeling off of the ink, while
there is no change in visual state of the logo marks formed in
structural colors (Examples 1 to 3 and Comparative Example 1).
[0075] In Comparative Example 1, among the logo marks formed in the
structural color, the ridge/groove height of the logo mark is 680
nm, which is out of range for producing the structural color
described above (equal to or smaller than 650 nm). Thus, no color
is produced.
[0076] As has been described, in the vehicle tire 10 according to
the embodiment, at least a part of the rubber member is indicated
in the different structural color from the colors of other regions,
which advantageously improves the durability of indication on the
rubber surface compared to the drawing in ink or the like.
[0077] In addition, information may be displayed in any color on
the surface of the rubber member by appropriately changing the
arrangement pitch or the ridge/groove height of the fine
ridged/grooved portions 34.
[0078] In the present embodiment, the fine ridged/grooved portions
34 include a cylindrical projection. However, no such limitation is
intended, and the fine ridged/grooved portions may have various
known shapes, which are capable of producing the structural color.
For example, the fine ridged/grooved portions 34 may include a
conical projection or a grid-like projection. Additionally, the
fine ridged/grooved structure 30 may include a hole or a grid-like
groove formed on the rubber surface. Also in this case, the holes
may be cylindrical or conical, and furthermore, microparticles or
the like may be arranged on the bottom portion of the conical hole
(apex of the cone).
[0079] In the present embodiment, the example of the rubber member
according to the present technology applied to the vehicle tire is
described. However, no such limitation is intended, and the rubber
member according to the present technology is suitable as various
known rubber members, in particular, any member vulcanized in a
manufacturing process.
[0080] In the present embodiment, only the logo mark 204 is
indicated in the structural color. However, no such limitation is
intended, and other information displayed on the sidewall portion
12 of the vehicle tire 10 may be also indicated in the structural
color. The fine ridged/grooved structure 30 may be formed on the
entire rubber member, such that the entire rubber member is
visually recognizable in the structural color.
[0081] In the present embodiment, the present technology is applied
to information indicated on the sidewall portion 12 of the vehicle
tire 10. However, no such limitation is intended, and the present
technology may be applied to information indicated on other
portions of the vehicle tire 10.
* * * * *