JP6523937B2 - tire - Google Patents

Description

  The present invention relates to a tire in which the surface of tread rubber is protected by a protective layer.

  The surface portion of a pneumatic tire (hereinafter referred to as a tire) mounted on a vehicle such as an automobile is generally made of a rubber material. It is known that rubber materials used for tires deteriorate when exposed to ozone contained in the atmosphere, and cracks and the like are easily generated.

  In particular, when many cracks are generated in the tread and the sidewall that are easily visible at the time of mounting on a vehicle, the appearance of the tire is impaired, which is not preferable. Further, the tread surface portion of the tread in contact with the road surface is repeatedly in contact with the road surface, and the wear progresses gradually, so cracking is hard to occur, but cracking is easily generated in the groove portion of the tread not in contact with the road surface.

  Then, in order to prevent the deterioration of the surface part of the tire by such ozone, the tire which protected the surface parts, such as tread rubber, by the protection layer using the material which has resistance to ozone is proposed (for example, patent) Literature 1). Specifically, it has been proposed to cover the surface portion of tread rubber or the like with a protective layer using urethane resin or the like.

Japanese Patent Publication No. 2003-535762

  However, the tire in which the surface portion is covered with the protective layer as described above has the following problems. That is, when the surface portion of the tire including the tread is coated with a material such as urethane resin, the coefficient of friction (μ) of the tire, particularly, the coefficient of friction on a wet road surface is significantly reduced.

  For example, a tire provided with a protective layer has a braking performance below 70% on a wet road surface as compared to a tire not provided with a protective layer.

  Since the thickness of the protective layer is approximately 500 μm or less, the protective layer of the tread portion of the tread is worn away and disappears if the tire is started to be used and traveled for a certain distance. For this reason, the coefficient of friction also increases. However, at the initial stage of use until the protective layer on the tread portion of the tread disappears, the coefficient of friction is significantly reduced, so that the performance is significantly reduced.

  Of course, it is also conceivable to ship after removing the protective layer of the tread portion of the tread, or to devise a manufacturing process so that the protective layer is not present on the tread portion of the tread. However, such a countermeasure is not preferable because it leads to a further increase in manufacturing cost.

  Therefore, the present invention has been made in view of such a situation, and provides a tire in which the protective layer of the tread portion of the tread disappears early with traveling while preventing deterioration of the surface portion due to ozone. To aim.

  A tire (tire 10) according to one aspect of the present invention includes a tread (tread 20) having a tread surface (tread surface 23) in contact with a road surface and a groove (groove 25) not in contact with the road surface And a protective layer (protective layer 100) for protecting the surface of the tread rubber (tread rubber 21). The protective layer is formed of a non-rubber-based material having resistance to ozone, overlaps the base portion (base portion 110) having a predetermined thickness along the tire radial direction, and the base portion, and is more than the base portion And an anchor portion (an anchor portion 120) which has entered the inside in the tire radial direction. The anchor portion extends along the tire width direction, and in the tread plan view, the width of the anchor portion in the tire circumferential direction is a slender shape shorter than the length of the anchor portion in the tire width direction, and in the tire circumferential direction At least one is formed.

  In one aspect of the present invention, the length of the anchor portion in the tire width direction may be 1/3 or more of the contact width in the tire width direction of the tire.

  In one aspect of the present invention, the anchor portion may terminate in a range on one side in the tire width direction with reference to a tire equator line.

  In one aspect of the present invention, the anchor portion may extend substantially in parallel with the tire width direction.

  In one aspect of the present invention, the width of the anchor portion in the tire circumferential direction may be 5 mm or less.

  In one aspect of the present invention, a ratio T1 / T2 of a thickness T1 of the protective layer at a portion where the base portion and the anchor portion are formed and a thickness T2 of the protective layer where only the base portion is formed May be 1.5 or more and 6.0 or less.

  According to the tire according to one aspect of the present invention, the protective layer of the tread portion of the tread can be eliminated early with traveling while preventing deterioration of the surface portion due to ozone.

FIG. 1 is a partial perspective view of the tire 10. FIG. 2 is a partial cross-sectional view of the tire 10 along the tire width direction. FIG. 3 is a partial development plan view of the tire 10. FIG. 4 is a partially enlarged cross-sectional view along the tire width direction of the tire 10 at the position of line F4-F4 in FIG. FIG. 5 is a partially enlarged cross-sectional view along the tire circumferential direction of the tire 10 at the position of line F5-F5 in FIG.

  Hereinafter, embodiments will be described based on the drawings. In addition, the same or similar reference numerals are given to the same functions or configurations, and the description thereof will be appropriately omitted.

(1) Schematic Configuration of Tire FIG. 1 is a partial perspective view of a tire 10 according to the present embodiment. FIG. 2 is a partial cross-sectional view of the tire 10 along the tire width direction. In FIG. 2, only half of the tire 10 in the tire width direction with respect to the tire equator line CL is illustrated. Specifically, FIG. 2 is a partial cross-sectional view of the tire 10 taken along the line F2-F2 shown in FIG. 3 described later.

  As shown in FIG. 1 and FIG. 2, the tire 10 has a tread 20 in contact with the road surface. Specifically, the tread 20 has a tread portion 23 in contact with the road surface and a groove 25 not in contact with the road surface. The groove 25 is a circumferential groove extending in the tire circumferential direction.

  The groove 25 forms a pattern of the tread 20. Although the pattern of the tread 20 is not limited to the pattern shown in FIG. 1, in order to secure the wet performance, the groove portion 25 occupying a constant ratio to the tread 20 is formed.

  The tread 20 is constituted by a tread rubber 21. As the tread rubber 21, a rubber in which a compounding agent is mixed with an appropriate rubber-based material is used according to the performance required for the tire 10.

  The tire 10 is a pneumatic tire and has a carcass 30 forming a skeleton of the tire 10. The carcass 30 is formed of an organic fiber or metal cord and is locked to the pair of beads 40. The structure of the carcass 30 is not particularly limited, but in general, a radial structure is preferably used.

  The bead 40 is a portion to be combined with a rim wheel (not shown), and secures the tire 10 to the rim wheel. The bead 40 is composed of a bead core and a bead filler. The bead core is formed of a plurality of wires, and the bead filler fills the gap between the carcass 30 folded back at the bead core and the bead core.

  A belt layer 50 is provided between the tread rubber 21 and the carcass 30. The belt layer 50 reinforces the skeleton of the tire 10 by the carcass 30. The belt layer 50 is applied with an appropriate structure according to the application of the tire 10. Generally, the belt layer 50 is configured by a pair of crossing belt layers where tire cords (not shown) cross each other, and a cap layer disposed at an end of the crossing belt layer in the tire width direction.

  As described above, although the specific structure of the tire 10 changes depending on the application, the tire 10 has the protective layer 100 (see FIG. 2) that protects the surface of the tread rubber 21 to improve the appearance quality. It is an object.

  For this reason, the tire 10 can be suitably used for a passenger car (including minivans, SUVs, and minicars) in which quality improvement of the appearance is often required. Of course, if similar requirements exist, the tire 10 may be a car for different applications, for example, a light truck such as a pickup truck, or a tire for a bus.

(2) Shape of Surface of Tread 20 As shown in FIG. 2, a thin protective layer 100 is provided on the surface of the tread 20. Specifically, the protective layer 100 is provided so as to cover the outer surface of the tread rubber 21 in the tire radial direction. That is, the surface of the tread rubber 21 is protected by the protective layer 100.

  In the present embodiment, the protective layer 100 protects not only the surface of the tread rubber 21 but the entire outer surface of the tire 10. Specifically, the protective layer 100 is provided on the shoulder portion SH, the sidewall portion SW, and the outer surface of the bead 40 of the tire 10.

  The protective layer 100 is formed of a non-rubber-based material having resistance to ozone. Specifically, the protective layer 100 prevents the rubber from being in direct contact with ozone in order to prevent the occurrence of cracks in the rubber on the outer surface of the tire 10.

  As described above, the protective layer 100 is preferably a thin film mainly composed of a non-rubber-based component which is not damaged by ozone and is excellent in durability. In the present embodiment, the protective layer 100 can be formed using a urethane foam sheet which is a foamed urethane (urethane resin) sheet.

(3) Configuration of Protective Layer 100 Next, the configuration of the protective layer 100 will be described more specifically. FIG. 3 is a partial development plan view of the tire 10. FIG. 4 is a partially enlarged cross-sectional view along the tire width direction of the tire 10 at the position of line F4-F4 in FIG. FIG. 5 is a partially enlarged cross-sectional view along the tire circumferential direction of the tire 10 at the position of line F5-F5 in FIG.

As shown in FIGS. 3 to 5, the protective layer 100 has a base portion 110 and an anchor portion 120.
The base portion 110 is formed on the entire surface of the tread 20, that is, the entire outer peripheral surface of the tire 10.

  The base portion 110 has a predetermined thickness in the tire radial direction. The predetermined thickness is preferably 30 μm or more and 200 μm or less.

  The anchor portion 120 overlaps the base portion 110. The anchor portion 120 is a portion that is inward in the tire radial direction than the base portion 110 (see FIGS. 4 and 5). Thus, the anchor portion 120 is formed to bite inward in the tire radial direction of the tread rubber 21 more than the base portion 110. The thickness of the anchor portion 120 in the tire radial direction can be, for example, about 600 μm.

  The ratio T1 / T2 (see FIG. 5) between the thickness T1 of the protective layer at the portion where the base portion 110 and the anchor portion 120 are formed and the thickness T2 of the protective layer where only the base portion 110 is formed is 1.5 or more And 6.0 or less, and more preferably 2.0 or more and 3.0 or less.

  The anchor portion 120 extends along the tire width direction. In the present embodiment, the anchor portion 120 extends substantially in parallel with the tire width direction, but may be inclined to some extent with respect to the tire width direction. However, the inclination angle is preferably 45 degrees or less based on the tire width direction in consideration of the early disappearance of the protective layer 100 of the tread portion 23 and other performance (impact on handling etc.), and is 30 degrees or less It is more preferable that

  The anchor portion 120 has an elongated shape in which the width of the anchor portion 120 in the tire circumferential direction is shorter than the length of the anchor portion 120 in the tire width direction in a tread plan view (see FIG. 3).

  Specifically, the anchor portion 120 has an elongated rectangular shape having a width in the tire circumferential direction sufficiently shorter than a length in the tire width direction. The width of the anchor portion 120 in the tire circumferential direction is preferably 5 mm or less.

  In addition, when the anchor part 120 inclines with respect to the tire width direction, the length in the tire width direction of the anchor part 120 means the length occupied in a tire width direction, and the tire peripheral direction of the anchor part 120 The width at means the width occupied in the direction orthogonal to the inclination direction of the anchor portion 120.

  Further, the shape of the anchor portion 120 in the tread plan view is not limited to a rectangular shape, and may be an elliptical shape or the like. Moreover, the surface along the tread width direction of the anchor part 120 may be somewhat uneven.

  At least one anchor portion 120 may be formed in the tire circumferential direction. For this reason, the thickness of the protective layer 100 locally increases in the portion where the base portion 110 and the anchor portion 120 are formed.

  In addition, as the anchor part 120 is shown with a dashed-dotted line in FIG. 3, in the tire circumferential direction, a predetermined space | interval may be provided and it may be formed in multiple numbers.

  The length of the anchor portion 120 in the tire width direction is preferably 1/3 or more of the contact width in the tire width direction of the tire 10. The contact width is the maximum length in the tire width direction in the contact area A shown in FIG. The contact area A is an area of the tread 20 in contact with the road surface in a state where a normal load is applied to the tire 10 set to the normal internal pressure.

  The normal internal pressure is the air pressure corresponding to the maximum load capacity of JATMA (Japan Automobile Tire Association) YearBook. The normal load is a load corresponding to the maximum load capacity. Also, instead of JATMA, overseas corresponding standards may be used.

  The anchor portion 120 may end in a range on one side in the tire width direction with reference to the tire equator line CL. Further, in this case, as shown by the alternate long and short dash line in FIG. 3, the anchor portion 120 is formed on both the one side (inside when the vehicle is attached) and the other side (outside when the vehicle is attached) May be

  In addition, the anchor part 120 may be formed so that it may straddle not only in one side in the tire width direction on the basis of the tire equator line CL but in both. Alternatively, anchor portion 120 may have a length equal to the ground contact width.

(4) Method of Forming Protective Layer 100 As described above, the protective layer 100 can be formed using a urethane foam sheet. Specifically, when vulcanizing and forming the tire 10, the urethane foam sheet cut into the shape of the tire 10 is set on the inner surface of the vulcanization mold.

  When setting a urethane foam sheet, a part which a urethane foam sheet overlaps in a tire peripheral direction is provided, or thickness of a part of urethane foam sheet is thickened. By vulcanizing and molding the tire 10 in which such a foamed urethane sheet is set, the protective layer 100 having the base portion 110 and the anchor portion 120 can be formed on the surface of the tread 20.

  Instead of the urethane foam sheet, a liquid having the same composition as urethane is applied to the outer surface of the tread 20, and the liquid corresponding to the anchor portion 120 is thickly applied to form the protective layer 100. May be

(5) Action / Effect Next, the action and effect of the tire 10 will be described. First, evaluation test results of tires according to comparative examples and examples will be described.

  Table 1 shows the structure of the tire concerning a comparative example and an example, and an evaluation test result.

The test conditions are as follows.
-Tire size: 195/65 R15
・ Setting internal pressure: 220kPa
・ Tire equipped vehicle type: Domestic FF passenger car (Toyota Auris)

  As shown in Table 1, in the tire according to Comparative Example 1, the anchor portion 120 like the tire 10 is not formed, and a protective layer of only the base portion is provided. That is, the thickness of the protective layer is constant without changing in the tire circumferential direction.

  The tire according to Comparative Example 2 and Examples 1 to 5 is provided with a protective layer 100 having a base portion 110 and an anchor portion 120. The number of anchor portions 120 in the tire circumferential direction is one.

  The difference between the tires according to Comparative Example 2 and Examples 1 to 5 is the length and width of the anchor portion 120 along the tire width direction, and the thickness of the protective layer in the portion where the anchor portion 120 is formed. It is ratio T1 / T2 (refer FIG. 5) with T1 and thickness T2 of the protective layer in which only the base part 110 is formed.

  As shown in Table 1, the length of the anchor portion 120 in the tire width direction is indicated by the ratio (1/4 to 1/1) of the contact width (TW) of the tire.

  In the tires according to Example 1 to Example 5, the travel distance until the protective layer 100 formed on the tread portion 23 of the tread 20 disappears is remarkably shortened. The “traveling distance to the disappearance of the protective layer” shown in Table 1 is an index with the traveling distance to the disappearance of the protective layer of the tire according to Comparative Example 1 as 100.

  As described above, in the tire 10 provided with the protective layer 100 having the base portion 110 and the anchor portion 120, a rigid step in the tire circumferential direction occurs at the position of the anchor portion 120. For this reason, when the vehicle on which the tire 10 is mounted travels, the anchor portion 120 in which the rigidity step is generated becomes a core by the vehicle turning back acceleration and deceleration etc., thereby protecting the tread 20 from the tread portion 23 Peeling of the layer 100 is promoted. As a result, the travel distance until the protective layer 100 formed on the tread portion 23 of the tread 20 disappears becomes short.

  That is, according to the tire 10, while the protective layer 100 prevents deterioration of the surface portion of the tire 10 such as the groove 25 due to ozone, the protective layer 100 of the tread portion 23 of the tread 20 disappears early with traveling. Can. For this reason, at the initial stage of use of the tire 10, the time (travel distance) in which the coefficient of friction decreases is significantly reduced, and the performance deterioration can be prevented.

  In particular, since the anchor portion 120 has an elongated shape in which the width in the tire circumferential direction is shorter than the length in the tire width direction of the anchor portion 120, the rigidity step tends to be extremely different in the tire circumferential direction. Are easy to promote.

  As described above, at least one anchor portion 120 may be formed in the tire circumferential direction, but even in such a case, peeling of the protective layer 100 is sufficiently promoted. In the tire 10, only the circumferential groove is formed as the groove portion 25, but in a general tire, a groove extending in the tire width direction is also formed.

  For this reason, if peeling of the protective layer 100 of the part in which the anchor part 120 is formed advances, it will be in the tire circumferential direction divided by the tread 23 which the peeling of the said protective layer 100 advanced, and the groove extended in the tire width direction. A step in the tire radial direction occurs between the tread surface 23 of the adjacent tread 20, and peeling of the protective layer 100 proceeds also on the tread surface 23 of the adjacent tread 20. As a result, peeling of the protective layer 100 proceeds in the entire tire circumferential direction. Of course, even in the case where no groove extending in the tire width direction is formed, although there is a difference in traveling speed, compared to the case where the anchor portion 120 is not formed at all, the rigidity step starting from the anchor portion 120 Peeling of the protective layer 100 proceeds prematurely throughout.

  As described above, the length of the anchor portion 120 in the tire width direction is preferably 1/3 or more of the contact width in the tire width direction of the tire 10. Thereby, as shown in Table 1, the traveling distance until the protective layer 100 disappears can be further shortened.

  Further, the anchor portion 120 may be terminated in a range on one side in the tire width direction based on the tire equator line CL. In this case, it is possible to suppress the material such as the urethane foam sheet necessary for the formation of the anchor portion 120 while advancing the peeling of the protective layer 100 at an early stage.

  In the present embodiment, the anchor portion 120 extends substantially in parallel with the tire width direction. Further, as described above, the width of the anchor portion 120 in the tire circumferential direction is preferably 5 mm or less.

  Thereby, a clear rigid level difference in the tire circumferential direction is generated, and peeling of the protective layer 100 can be advanced at an early stage.

  As described above, the ratio T1 / T2 between the thickness T1 of the protective layer 100 in the portion where the base portion 110 and the anchor portion 120 are formed and the thickness T2 of the protective layer 100 where only the base portion 110 is formed. Is preferably 1.5 or more and 6.0 or less. Thereby, while promoting the exfoliation of the protective layer 100 at an early stage, it is possible to suppress adverse effects on other performances such as quietness and ride comfort.

(6) Other Embodiments Although the contents of the present invention have been described above according to the embodiments, the present invention is not limited to these descriptions, and various modifications and improvements are possible. It is obvious to the trader.

  For example, the protective layer 100 may not necessarily be urethane, as long as it is a non-rubber material having ozone resistance, and for example, polyethylene and polypropylene can be used.

  In the embodiment described above, the protective layer 100 is formed not only on the tread 20 but also on the outer surface of the shoulder portion SH, the sidewall portion SW and the bead 40, but the protective layer 100 is formed only on the outer surface of the tread 20 May be Alternatively, the protective layer 100 may be formed on the tread 20, the shoulder portion SH and the sidewall portion SW which are relatively easy to visually recognize.

  Further, as described above, in the tire 10, only the circumferential groove is formed as the groove portion 25. However, in the tire 10, a groove (width direction groove or lug groove) extending in the tire width direction may be formed. .

  While the embodiments of the present invention have been described above, it should not be understood that the statements and drawings that form a part of this disclosure limit the present invention. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this disclosure.

10 tires
20 tread
21 Tread rubber
23 tread area
25 groove
30 carcass
40 beads
50 belt layers
100 protective layer
110 Base
120 anchor part

Claims (6)

A tread having a tread portion in contact with a road surface and a groove portion not in contact with the road surface;
And a protective layer for protecting the surface of the tread rubber constituting the tread, wherein the tire comprises:
The protective layer is
It is made of non-rubber based material that is resistant to ozone,
A base portion having a predetermined thickness in a tire radial direction;
And an anchor portion which overlaps with the base portion and which is inward of the base portion in the tire radial direction;
The anchor portion is
While extending along the tire width direction,
In the tread plan view, the width of the anchor portion in the tire circumferential direction is a slender shape shorter than the length of the anchor portion in the tire width direction,
The tire formed at least one in the tire circumferential direction.   The tire according to claim 1, wherein a length of the anchor portion in the tire width direction is 1/3 or more of a contact width in the tire width direction of the tire.   The tire according to claim 2, wherein the anchor portion terminates in a range on one side in a tire width direction with reference to a tire equator line.   The tire according to any one of claims 1 to 3, wherein the anchor portion extends substantially in parallel with the tire width direction.   The tire according to any one of claims 1 to 4, wherein a width of the anchor portion in a tire circumferential direction is 5 mm or less.   The ratio T1 / T2 of the thickness T1 of the protective layer at the portion where the base portion and the anchor portion are formed to the thickness T2 of the protective layer where only the base portion is formed is 1.5 or more and 6.0 or less The tire according to any one of claims 1 to 5, which is

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