Hydrophobic pattern of tire tread grooves

Abstract

A tread for a pneumatic tire includes a plurality of grooves, the grooves including a groove surface (122) and a plurality of elements (410) spaced apart from one another in an arrangement on the groove surface (122). Each element (410) has a shape that defines a volume, the shape including a first cross-sectional shape (425) in a plane (420) parallel to the groove surface (122) and a second cross-sectional shape (435) in a plane (430) perpendicular to the groove surface (122). The arrangement includes a void volume in the space between the elements (410) and a porosity between 0.5 and 0.75, the porosity being defined as the ratio of the void volume to the total volume of the elements (410) in the arrangement.

Description

[Technical Field]

[0001] This invention relates to a hydrophobic pattern in the tread grooves of a tire, and consequently to a tread with high drainage performance. [Background technology]

[0002] Some research in the field of pneumatic tires focuses on obtaining treads that improve wet grip performance.

[0003] As is known to those skilled in the art, the grip of a tread on a wet road surface is due to the tread's ability to remove the layer of water that forms between the road surface and the tread. This layer of water inevitably impairs the effective grip of the tread on the road surface.

[0004] The tread has grooves to facilitate the removal of water layers. In fact, the grooves in the tread carry out a drainage process.

[0005] In this regard, it is important to explain how the wet performance of a pneumatic tire is influenced by the first drainage process, in which the layer of water between the tread and the road surface is removed from the tread, and the contact process, in which the tread blocks adhere to the road surface. The shorter the drainage process and the more water is removed, the more efficient the wet grip becomes.

[0006] As is well known, a solution to shorten the drainage process and increase the amount of water discharged is to increase the volume of grooves in the tread. While this solution succeeds in shortening and making the drainage process more effective, it reduces the contact surface between the tread and the road surface, resulting in disadvantages to the contact process itself, and consequently to braking and steering. Furthermore, it is known that increasing the volume of grooves can negatively affect the wear resistance of the tread.

[0007] In the tire industry, it is known that certain groove structures in the tread can be advantageous in more quickly draining water. Such solutions are highly advantageous because they only involve the groove surface and not the number and / or dimensions of the grooves, and therefore do not reduce the contact surface between the tread itself and the road surface.

[0008] There is still a need to improve the groove surface of the tire tread to provide better hydrophobicity and enhance drainage. [Overview of the project]

[0009] According to a first aspect of the present invention, a tread for a pneumatic tire is provided, the tread is, It includes multiple grooves, and the grooves are groove surface and Multiple elements that are spaced apart from each other in their arrangement on the groove surface and Includes, Each element has a shape that defines its volume, and the shape is A first cross-sectional shape in a plane parallel to the groove surface, wherein the minimum dimension of the first cross-sectional shape defined on the groove surface is such that the width w of the element's bottom is 0.1 mm ≤ w ≤ 3 mm, and the first cross-sectional shape is such that A second cross-sectional shape in a plane perpendicular to the groove surface, wherein the maximum dimension of the second cross-sectional shape from the bottom to the top of the groove surface is defined by the height h of the element, where 0.1 mm ≤ h ≤ 3 mm, and the second cross-sectional shape is defined by The aspect ratio obtained by dividing height h by width w is at least 1 and at most 30. Includes, The arrangement is, The volume of voids in the space between elements, A void ratio of 0.5 to 0.75, defined as the ratio of the void volume to the total volume of the element in the arrangement. Includes.

[0010] The inventors have understood that it is possible to change the physical properties of the groove surface of a tread in at least one of the groove surfaces of a pneumatic tire by arranging elements at intervals. In particular, by incorporating elements into the groove surface, it is possible to change the hydrophobicity of the groove surface.

[0011] Within the scope of the present invention, the hydrophobicity of a surface corresponds to the contact angle formed by a static water droplet when in contact with said surface. Thus, a contact angle greater than 90° corresponds to a hydrophobic surface, and a contact angle less than 90° corresponds to a hydrophilic surface.

[0012] It will be understood that the space between the elements is defined by the three-dimensional space available between the elements in the arrangement, i.e., between the plane of the groove surface and the plane crossing the tops of the elements (these two planes are separated by a height h). The elements may be regarded as protrusions from the groove surface, even if they are created by removing material from the initial groove surface, i.e., by lowering the groove surface. The groove surface is the lowest surface within the groove when the tread is viewed from the outside. The void volume may thus be regarded as minus the total volume of the elements. In other words, the void volume is defined as the total available area between the elements multiplied by its height h. The void volume can be defined regardless of whether the elements are formed by adding material to the initial groove surface or by removing material from the initial groove surface.

[0013] It will be understood that the porosity is defined as the ratio of the total void volume to the total volume of the elements in the arrangement, e.g., the total void volume divided by the total element volume in any total volume of the arrangement on the groove surface. For example, if the porosity is 0.5, the volume of the elements will be twice the void volume within the arrangement. As the porosity increases, the total void volume increases and the space between adjacent elements increases, so that it is expected that the contact angle brought about by the elements will increase, at least when the arrangement is newly formed.

[0014] However, it has been found beneficial to limit the porosity to 0.75 so that the relative volume of the elements remains greater than the void volume. The inventors have noticed that the volume of the elements is important for their durability, and increasing their volume provides resistance to aging, otherwise, corrosion of the elements over time tends to reduce the hydrophobicity of the groove surface. Therefore, the porosity is selected between 0.5 and 0.75. This is because it has been found that this provides a balance between good hydrophobicity when the arrangement is newly formed and resistance to aging over the service life of the tread. In some preferred embodiments, the porosity is selected, for example, between 0.55 and 0.75, between 0.6 and 0.75, between 0.65 and 0.75, between 0.7 and 0.75, between 0.5 and 0.7, between 0.5 and 0.65, between 0.5 and 0.6, between 0.5 and 0.55.

[0015] The placement of a plurality of elements on the groove surface means that they are physically distinct from the groove surface, for example, protruding from the surface or created by embossing on the surface. The elements present on the groove surface have the effect of modifying the hydrophobicity of the surface. In some embodiments, the plurality of elements are placed on at least two, for example, at least three of the plurality of groove surfaces. In some embodiments, the plurality of elements are placed on substantially all of the groove surface, for example, the groove surface is completely covered with elements. In a preferred embodiment, the elements protrude from the groove surface. Preferably, the elements are spaced apart from each other in the arrangement of the elements protruding on the groove surface.

[0016] It will be understood that a groove may have one or more groove surfaces. For example, a groove may have a bottom surface and two side wall surfaces, and the groove may have a substantially U-shaped cross-section in a plane perpendicular to the surface of the tire tread. However, it will be understood that a groove may have any suitable and / or desirable cross-section, and thus may include any suitable and / or desirable number of surfaces. In some embodiments, a groove may include only straight surfaces having, for example, a polygonal cross-section. In some embodiments, a groove may include a curved surface, for example, a semicircular cross-section. In some embodiments, a groove may include any suitable and / or desirable combination of curved and / or straight surfaces, for example, a bullet shape having straight sides and a curved (e.g., dome-shaped) bottom surface.

[0017] It will be understood that the hydrophobicity of a groove surface can be directly influenced by one or more of the element size (e.g., element volume), element shape (e.g., first and second cross-sectional shapes, aspect ratio), and the space between adjacent elements (e.g., void volume). The porosity may therefore be considered the primary parameter of the subject, as it links the element volume with the void volume defined by the space between elements.

[0018] Depending on the embodiment, the second cross-sectional shape may be any suitable and / or desirable shape. The overall shape of the element may be, for example, generally cylindrical, conical, cubic, rectangular, polygonal, pyramidal, parabolic, or hyperbolic. In a series of embodiments, the second cross-sectional shape is square or rectangular. Thus, the overall shape of the element may be cylindrical or triangular prism.

[0019] According to a second aspect of the present invention, a tread for a pneumatic tire is provided, the tread is, It includes multiple grooves, and the grooves are groove surface and Multiple elements that are spaced apart from each other in their arrangement on the groove surface and Includes, Each element has a cylindrical or triangular prism shape that defines its volume. The arrangement is, The volume of voids in the space between elements, A void ratio of 0.5 to 0.75, defined as the ratio of the void volume to the total volume of the element in the arrangement. Includes.

[0020] In the embodiment of this second aspect, the arrangement of the groove surface includes a plurality of cylindrical and / or triangular prism-shaped elements. This has been found to increase the contact angle between the water droplet and the surface to a point that ensures a shorter drainage process. Indeed, as is known to those skilled in the art, the larger the contact angle between the water droplet and the surface, the more water tends to be discharged from the surface, and thus the shorter the drainage process.

[0021] At least some embodiments of this second aspect may include one or more features of the first aspect. In some embodiments of this second aspect, the cylindrical or triangular prism shape includes a first cross-sectional shape in a plane parallel to the groove surface, where the minimum dimension of the first cross-sectional shape defined on the groove surface defines the width w of the element, and 0.1 mm ≤ w ≤ 3 mm. In some embodiments of this second aspect, the cylindrical or triangular prism shape includes a second cross-sectional shape in a plane perpendicular to the groove surface, where the maximum dimension of the second cross-sectional shape from the groove surface defines the height h of the element, and 0.1 mm ≤ h ≤ 3 mm. In some embodiments of this second aspect, the cylindrical or triangular prism shape includes an aspect ratio of height h divided by width w, which is at least 1 and at most 30.

[0022] The inventors have generally found that as the volume of an element increases, the surface area of ​​the element's top increases, the contact angle (for example, of the groove surface containing the element) decreases, and the apparent hydrophobicity of the groove surface decreases when a new element is formed. Therefore, it can be assumed that minimizing the volume of an element increases the contact angle, and consequently improves the hydrophobicity of the tread. Reducing the volume of an element also tends to increase the space between elements, thereby increasing the porosity.

[0023] However, the inventors also understood that the hydrophobicity imparted to the groove surface by the elements can change as the elements corrode due to the aging and deterioration of the tire tread, for example, from the use of tires on roads. The inventors found that it is beneficial to limit the porosity so that the volume of the elements is not too small compared to the void volume. They found that a larger volume of elements generally resulted in a smaller change in the contact angle over time.

[0024] Therefore, the inventors understood that the smaller the volume of the element, the lower its resistance to aging, which in turn leads to more rapid corrosion and can affect the hydrophobicity imparted by the element. However, predicting how aging will affect the geometric shape of the element and, consequently, the hydrophobicity of the groove surface is not straightforward. The inventors understood that a compromise could be found between maximizing the volume of the element to improve resistance to aging and minimizing the surface area of ​​the protrusion apex.

[0025] In some embodiments of the first aspect, the second cross-sectional shape may be any suitable and / or desirable shape. However, the inventors have found that a compromise can be found by selecting elements such that the second cross-sectional shape has a greater dimension at the bottom (e.g., adjacent to the groove surface) than at the top (e.g., the surface that will come into contact with water). The inventors have found that by widening the bottom of the element, for example by reducing the surface area of ​​the top of the element, the element volume can be increased without negatively affecting the hydrophobicity of the surface. As a result, the inventors have found that it is desirable to configure the elements such that the second cross-sectional shape is not rectangular, such that the element is a non-columnar structure (rather than an element shape having a constant width from the bottom to the top of the element). Such elements do not have a cylindrical or triangular prism shape.

[0026] Each element has a shape that may include more than one second cross-sectional shape in a plane perpendicular to the groove surface, for example, if the first cross-sectional shape has both width and length. The second cross-sectional shape that has the greatest influence on the hydrophobicity of the groove surface is the second cross-sectional shape that includes the minimum dimension defined on the groove surface, i.e., the second cross-sectional shape that includes the width w of the element at its bottom. Thus, in a preferred embodiment, the second cross-sectional shape includes a width w and a height h, and the width w at the bottom of the second cross-sectional shape is greater than the corresponding width w' at the top of the second cross-sectional shape. In other words, the second cross-sectional shape tapers from its bottom (on the groove surface) to its top surface (furthest from the groove surface). Preferably, the second cross-sectional shape is selected not to be rectangular or square.

[0027] This is considered novel and original in itself. Therefore, viewed from a third aspect, the present invention provides a tread for a pneumatic tire, the tread is, It includes multiple grooves, and the grooves are groove surface and Multiple elements that are spaced apart from each other in their arrangement on the groove surface and Includes, Each element is, A first cross-sectional shape in a plane parallel to the groove surface, wherein the minimum dimension of the first cross-sectional shape defined on the groove surface is the first cross-sectional shape that defines the width w of the bottom of the element, A second cross-sectional shape in a plane perpendicular to the groove surface, wherein the maximum dimension of the second cross-sectional shape from the bottom to the top of the groove surface is defined by the second cross-sectional shape and the height h of the element. Having a shape that includes, The second cross-sectional shape includes a width w and a height h, where the width w at the bottom of the second cross-sectional shape is greater than the corresponding width w' at the top of the second cross-sectional shape.

[0028] By widening the bottom of the elements, their volume can be increased without negatively affecting the surface hydrophobicity provided by the top of the second cross-sectional shape. The inventors have found that such elements improve resistance to aging. Therefore, advantageously, the inventors have found that arranging elements with a second cross-sectional shape having a wide bottom achieves a good compromise between maximizing the volume of the elements to improve resistance to aging and minimizing the contact area between the elements and static water droplets. It will be understood that the corresponding width w' at the top of the second cross-sectional shape is measured in the same orientation as the width w at the bottom.

[0029] At least some embodiments of this third aspect may include one or more features of the first aspect. In some embodiments of this third aspect, the shape of each element defines a volume, and the arrangement includes a void volume in the space between elements and a void ratio of 0.5 to 0.75, where the void ratio is defined as the ratio of the void volume to the total volume of the elements in the arrangement. In some embodiments of this third aspect, the width w of the element is selected such that 0.1 mm ≤ w ≤ 3 mm. In some embodiments of this third aspect, the height h of the element is selected such that 0.1 mm ≤ h ≤ 3 mm. In some embodiments of this third aspect, the shape includes an aspect ratio of height h divided by width w, which is at least 1 and up to 30.

[0030] Furthermore, the inventors found that the greater the curvature of the upper surface of the element (e.g., the surface in contact with the water droplet), the greater the contact angle of the static water droplet. Therefore, for example, the inventors found that the contact angle formed between a static water droplet and a groove containing a columnar element arrangement (e.g., including a second rectangular cross-sectional shape) is smaller (e.g., less hydrophobic) than the contact angle formed between the static water droplet and an element arrangement containing a second cross-sectional shape having a curved, filleted, rounded, or chamfered apex. This effect is further observed as the radius of curvature of the fillet (e.g., the degree of rounding of the apex) increases, or as the slope of the bevel (e.g., a chamfered or curved surface) decreases (e.g., as the rounding increases or the slope decreases, the contact angle formed between the static water droplet and the element increases, and e.g., becomes more hydrophobic).

[0031] In some embodiments, the second cross-sectional shape may have, for example, straight sides and generally taper from its base to its apex. For example, the second cross-sectional shape may generally be triangular, a truncated triangle, or a trapezoid. However, the inventors have further found that it is beneficial to avoid angles between the sides and the apex of the second cross-sectional shape. As described above, in some preferred embodiments, the second cross-sectional shape includes a curved, filleted, rounded, or chamfered apex. In at least some embodiments, the second cross-sectional shape tapers from its base to its apex and includes sides extending from the base to the apex, and a curved or angled transition between the sides and the apex, with the apex being flat. The sides may extend from the base to the apex at an angle of about 90° (e.g., a column with a filleted or chamfered apex) or at an interior angle of 25° to 85° (e.g., a triangle with a truncated apex). The sides can be straight or curved.

[0032] In some preferred embodiments, the second cross-sectional shape may generally be semicircular, parabolic, hyperbolic, or semi-elliptic. Depending on the embodiment, the second cross-sectional shape is generally parabolic or hyperbolic (for example, the overall shape of the element is a parabolic or hyperbolic surface, such as a continuous curved structure with the tip cut off at the bottom).

[0033] In some embodiments, the second cross-sectional shape is a polygon, preferably with a flattened or rounded top (for example, to create a gradual change from the side to the top of the shape). In some embodiments, the second cross-sectional shape is a polygon with four sides, for example, a square or rectangle with four interior angles greater than 90° and two interior angles of 90° or less (for example, preferably the two angles of 90° or less are at the bottom of the cross section adjacent to the groove surface), for example, a trapezoid. In some embodiments, the second cross-sectional shape is a rounded trapezoid. In some embodiments, the second cross-sectional shape is a polygon with six sides, for example, a square or rectangle with a chamfered edge on the top surface of the element. In some embodiments, the second cross-sectional shape includes a curved edge that transitions from the side to the top, for example, a square or rectangle with a filleted top to create a gradual change from the side to the top surface of the element. In some embodiments, the second cross-sectional shape is a truncated or flattened hyperbola, for example, the hyperbola shape includes, for example, a flattened apex with the tip truncated at its narrowest point, such that the width of the bottom of the cross-section is greater than the width of the apex. In some embodiments, the second cross-sectional shape is a truncated or flattened parabola, for example, the parabola shape includes a flattened apex. In some embodiments, the second cross-sectional shape may include at least one straight edge and at least one curved edge.

[0034] Preferably, the apex of the second cross-sectional shape includes a flat apex without sharp corners, for example, the apex includes a curved side or rounded edge, and the three-dimensional element includes a rounded shape where it transitions from a flat top surface to a side surface. For example, in some embodiments, the planar apex may transition to the bottom of the shape by a sine or conical function, such that the width of the bottom of the element is greater than that of the apex.

[0035] In some embodiments, the second cross-sectional shape is a plane perpendicular to the groove surface and perpendicular to the circumferential direction. In some embodiments, the second cross-sectional shape is a plane perpendicular to the groove surface and parallel to the circumferential direction.

[0036] In some embodiments, the height h is at least 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm. In some embodiments, the height h is up to 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm. In some embodiments, the height h is between 0.1 mm and 1 mm. In some other embodiments, the height h is up to 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

[0037] In some embodiments, the aspect ratio of the element is greater than 1, for example, the second cross-sectional shape has a height, h greater than the width, w of the first cross-sectional shape. In preferred embodiments, the aspect ratio of the element is substantially greater than 1, for example, the ratio of height, h to width, w is at least 1.5, 2, 3, or 4.

[0038] Each element includes a first cross-sectional shape in a plane parallel to the groove surface. Depending on the embodiment, the first cross-sectional shape may be any suitable and / or desirable geometric shape. For example, the first cross-sectional shape may be a square, a circle, an ellipse, a rectangle, a triangle, a polygon, a mathematical symbol, an algebraic symbol, an irregular polygon, e.g., a polyomino, e.g., a tetromino, e.g., a pentomino. The first cross-sectional shape may be selected or modified independently of the second cross-sectional shape, and it will be understood that as a result, the element may have a variety of different three-dimensional shapes.

[0039] In some embodiments, the width w is at least 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm. In some embodiments, the width w is up to 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm. In some embodiments, the width w is between 0.1 mm and 1 mm. In some other embodiments, the width w is up to 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

[0040] In some embodiments, the first cross-sectional shape generally has a certain width and may be, for example, a point-like element. In some other embodiments, the first cross-sectional shape may have a length l greater than the width w. For example, the first cross-sectional shape may be an elongated rectangle (optionally having a curved, filleted, rounded, or chamfered top). More generally, in some embodiments, the first cross-sectional shape is an elongated strip defining a length l much greater than the width w. In some embodiments, the length l is at least 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. In some embodiments, the length l is up to 5 mm, 10 mm, 15 mm, or 20 mm. In some embodiments, the length l is up to 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, or 100 mm. In some embodiments, the length l is between 1 mm and 100 mm.

[0041] In some embodiments, the elongated strip may extend partially or entirely along the circumferential direction of the groove. For example, in some embodiments, the first cross-sectional shape may be an elongated rectangle or strip that connects to itself and forms a loop along the groove surface. In some embodiments, the strip may have an aspect ratio of length l to width w of 7:1 or greater, for example, 10:1 or greater, for example, 15:1 or greater. In some embodiments, the elongated rectangle may have an aspect ratio of 7:1 to X:1, where X is equal to πd / w, where d is the diameter of the tread and w is the groove width. This means that for a large tread with a diameter of about 1000 mm and a groove width of 20 mm, for example, X is 157. In some other embodiments, the elongated strip may extend at an angle other than 0 with respect to the circumferential direction of the groove, for example, at an angle of at least 30°, 40°, 45°, 50°, 60°, 70°, 80°, or at an angle of about 90° (i.e., perpendicular to the circumferential direction of the groove).

[0042] More generally, it will be understood that the first cross-sectional shape may have any suitable and / or desirable orientation with respect to the groove surface. In some embodiments, the first cross-sectional shape may have a longitudinal axis oriented parallel to the outer circumference of the tire and the groove surface. For example, when the first cross-sectional shape is rectangular, the rectangle may be oriented to form a continuous line extending around the outer circumference of the tire. In some embodiments, the first cross-sectional shape may have a longitudinal axis adjusted perpendicular to the groove wall surface; for example, the first cross-sectional shape may extend across the width of the groove. In some embodiments, the first cross-sectional shape may extend diagonally across the groove; for example, a line or elongated rectangle may extend diagonally across the groove surface.

[0043] To ensure that the element exhibits resistance to aging, the element volume is preferably about 0.1 mm 3 Larger. Depending on the embodiment, the element is 0.2 mm 3 Larger, for example, 0.25 mm 3 Larger, for example, 0.3 mm 3 Larger, for example, 0.35 mm 3Larger, for example, 0.4 mm 3 Larger, for example, 0.45 mm 3 Larger, for example, 0.5 mm 3 Larger, for example, 0.55 mm 3 Larger, for example, 0.6 mm 3 It may have a larger element volume. The inventors have found that when the element volume is increased to be larger than 0.1 mm 3 it becomes easier to maintain a relatively large contact angle even when the tire is subject to aging, but when the volume is too large, the effect tends to level off. When the element volume increases, as described below, the porosity of the pattern can be affected. Therefore, the element has a maximum of about 0.5 mm 3 , for example, a maximum of about 0.6 mm 3 , for example, a maximum of about 0.7 mm 3 , for example, a maximum of about 0.8 mm 3 , for example, a maximum of about 0.9 mm 3 , for example, a maximum of about 1.0 mm 3 , for example, a maximum of about 1.1 mm 3 , for example, a maximum of about 1.2 mm 3 , for example, a maximum of about 1.3 mm 3 , for example, a maximum of about 1.4 mm 3 , for example, a maximum of about 1.5 mm 3 and may have an element volume of up to about 1.5 mm. In some embodiments, the element may have an element volume of 0.1 - 1.5 mm 3 .

[0044] In some embodiments, as described above, the element may extend not in a dot shape but instead in the form of an elongated strip having a length l much larger than the width w. In the case of such an element, the element volume is X times the range of 0.1 - 1.5 mm 3 where X is πd with respect to the diameter d of the tread.

[0045] It will be understood that the void volume is determined by the arrangement via the spacing of the elements, i.e., the spacing between the elements. The spacing between adjacent elements in the arrangement may be defined by at least a first nearest neighbor spacing, s. In some embodiments, the arrangement may be further characterized by a second nearest neighbor spacing, s2, where the second nearest neighbor spacing is greater than the first nearest neighbor spacing. Such nearest neighbor spacings may be defined for either random or regular arrangements.

[0046] In some embodiments, the arrangement of multiple elements is random. In such arrangements, the elements may be spaced apart from one another at a defined average interval, despite the randomness of the arrangement. In some embodiments, the arrangement of multiple elements is regular. Regular arrangements may occur alone, or they may be repeated, for example, in a pattern. In some preferred embodiments, the arrangement of multiple elements is a regular pattern. It will be understood that the elements may be arranged in any suitable and / or desirable pattern. In some embodiments, the pattern may be, for example, an isotropic pattern, identical in all directions. In some embodiments, the pattern may be anisotropic, for example, the pattern may have different nearest neighbor spacings in different directions.

[0047] In some embodiments, the pattern may be isotropic. For example, the pattern may be a cubic pattern, where each element (e.g., a central element) is spaced equally apart from four nearest elements, and three nearest elements form an angle of either 90 degrees or 180 degrees, for example, forming a repeating square pattern. In some embodiments, the pattern may be a repeating diamond pattern, where each element (e.g., a central element) is spaced equally apart from four nearest elements, and three nearest elements form an angle of either less than 90 degrees or less than 180 degrees. In some embodiments, the pattern may be a repeating hexagonal pattern, where each element is spaced equally apart from six nearest elements.

[0048] In some embodiments, the pattern may be anisotropic. For example, the pattern may be a rectangular pattern, where each element (e.g., a central element) has two nearest neighbor elements at 180 degrees to the central element and two second nearest neighbor elements at 180 degrees to the central element, and the first nearest neighbor spacing is smaller than the second nearest neighbor spacing. For example, the pattern may be a parallelogram pattern, where each element (e.g., a central element) has two nearest neighbor elements at 180 degrees to the central element and two second nearest neighbor elements at 180 degrees to the central element, and the angles formed between any first nearest neighbor element, the central element and any second nearest neighbor element are not 90 degrees.

[0049] It will be understood that the pattern may be defined with respect to the central position of the first cross-sectional shape, such that the first nearest neighbor spacing, s, is calculated from the center of the first cross-sectional area. Therefore, the pattern arrangement is completely independent of the first cross-sectional shape of the element.

[0050] In some embodiments, the elements are spaced apart in the arrangement at typical or average intervals of 50 to 500 μm, e.g., 100 to 500 μm, e.g., greater than 100 μm, e.g., greater than 200 μm, e.g., greater than 300 μm, e.g., greater than 400 μm, e.g., less than 500 μm, e.g., less than 400 μm, e.g., less than 300 μm, e.g., less than 200 μm, e.g., less than 100 μm. In some embodiments, the elements are spaced apart in the arrangement at typical or average intervals of 0.5 mm to 1.5 mm. In some other embodiments, the elements are spaced apart in the arrangement at typical or average intervals of up to 2 mm, 2.5 mm, or 3 mm. In various embodiments, the arrangement is an isotropic pattern, and this interval is the first nearest neighbor interval.

[0051] It will be understood that elements may be formed by any suitable and / or desirable method. For example, elements may be formed on the groove surface by removing material from the groove surface by, for example, drilling, milling, ion milling, machining, electrical discharge machining, laser engraving, laser etching, plasma etching, chemical etching, photolithography, X-ray lithography, electron beam lithography, etching with plasma, gas, or liquid, probe microscopy, atomic force microscopy, nanoindentation microscopy, or evaporation. For example, elements may be formed on the groove surface by replacing material on the groove surface by, for example, embossing, stamping, molding, or forging. For example, elements may be formed on the groove surface by depositing material on the groove surface by, for example, chemical vapor deposition, physical vapor deposition, electroplating, 3D metal printing, additive manufacturing, or electrospinning.

[0052] Depending on the embodiment, laser engraving technology may be used. The present invention therefore extends to a method for creating a tread, according to any one of the embodiments disclosed herein, which utilizes laser engraving technology.

[0053] Depending on the embodiment, molding techniques are used. The present invention therefore extends to a method for creating a tread, according to any one of the embodiments disclosed herein, which uses molding techniques. The present invention further extends to a mold configured for creating a tread, according to any one of the embodiments disclosed herein.

[0054] Depending on the embodiment, the elements may be formed on the groove surface using molding or casting techniques, and the mold may include a negative of the element pattern created by any suitable and / or desired technique. For example, the mold may be formed by one or more suitable techniques such as drilling, milling, ion milling, machining, electrical discharge machining, electroplating, laser etching, 3D metal printing, additive manufacturing, plasma etching, chemical etching, photolithography, X-ray lithography, electron beam lithography, embossing, stamping, molding, forging, etching by plasma, gas, or liquid, probe microscopy, atomic force microscopy, nanoindentation microscopy, chemical vapor deposition, physical vapor deposition, evaporation, and electrospinning.

[0055] In some embodiments, the arrangement of multiple elements is substantially identical across the groove surface. This can help ensure reliable hydrophobic performance. In some embodiments, multiple different arrangements may exist within a single groove. For example, the bottom surface of the groove (e.g., a groove surface substantially parallel to the outer surface of a pneumatic tire) may include a first arrangement of elements, and the walls of the groove (e.g., a groove surface substantially perpendicular to the surface of a pneumatic tire) may include a second arrangement of elements, where the first and second arrangements are different. In some embodiments, the first and second arrangements may include elements having the same first and / or second cross-sectional shape and / or aspect ratio and / or volume, but the elements may be spaced differently in the first and second arrangements. In some embodiments, the spacing of elements in the first and second arrangements may be identical, but the elements may have different first and / or second cross-sectional shapes and / or aspect ratios and / or volumes. It will be understood that these parameters may be interrelated by a defined range with respect to porosity.

[0056] In some embodiments, a single groove surface may include multiple arrangements of elements. For example, a groove surface may include an array of arrangements. For example, a groove surface may include a first arrangement extending along the circumferential direction of the groove and a second arrangement extending parallel to the first arrangement, and the groove surface may include two different arrangements extending along the circumferential direction of the groove (e.g., around the outer circumference of the tire). In some embodiments, the first arrangement may be arranged to extend across the width of the groove, and the second arrangement may be arranged to extend across the width of the groove adjacent to the first arrangement, and the array may include alternating two different arrangements along the circumferential direction of the groove. In various embodiments, a groove surface may include any suitable and / or desired number and configuration of arrangements, one, two or more arrangements.

[0057] In some embodiments, the grooves extend along the circumferential direction of the tread (e.g., summer tires). In other embodiments, the grooves are arranged in a V-shape and extend at an angle to the circumferential direction of the tread (e.g., winter tires).

[0058] In some embodiments, the grooves have a width ranging from 0.2 to 20 mm. In some embodiments, the grooves have a depth of at least 1 mm, preferably at least 1.6 mm, and more preferably at least 2 mm. In some embodiments, the grooves have a depth of 2 to 3 mm.

[0059] The disclosures herein relate to grooves formed in the treads of pneumatic tires. The hydrophobicity of the groove surface is therefore considered in light of groove surfaces made of rubber material or rubber-based polymer material. In some embodiments, the tread is made of a diene rubber compound. Diene rubbers such as natural rubber, isoprene rubber, and butadiene rubber contain repeating units derived from diolefins having conjugated carbon double bonds. The properties of synthetic diene rubbers can be specially adjusted by copolymerization of diolefin monomers with other monomers, and synthetic diene rubbers are used in a wide range of applications, including tire treads. Styrene-butadiene rubber (referred to herein as "SBR") is an example of butadiene rubber produced by polymerization of styrene and butadiene. In some embodiments, the tread is made of a silica-containing diene rubber compound, such as an SBR-silica compound.

[0060] A typical SBR-silica rubber compound is prepared according to the following composition (where "phr" is the weight relative to 100 units of rubber weight):

[0061] [Table 1]

[0062] S-SBR has a styrene content of 10-45% and a vinyl content of 20-70%, with a density of 800-1500 × 10⁻¹⁰, respectively. 3 and 500~900×10 3 This polymer is obtained through a solution polymerization process at an average molecular weight.

[0063] BR is a polymer made of polybutadiene.

[0064] Silica is approximately 170m 2 It is a filler with a surface area of ​​ / g and is sold by EVONIK under the name Ultrasil VN3.

[0065] The carbon black is N134.

[0066] The silane binder is sold by EVONIK under the name SI75.

[0067] TBBS is an abbreviation for N-tert-butyl-2-benzothiadylsulfenamide, a compound used as a vulcanization accelerator.

[0068] DPG is an abbreviation for diphenylguanidine compound, which is used as a vulcanization accelerator.

[0069] Some embodiments of the present invention will be further described below with reference to the non-limiting examples and accompanying drawings. [Brief explanation of the drawing]

[0070] [Figure 1] This diagram shows the tread pattern of a pneumatic tire containing multiple grooves. [Figure 2] Figure 1 shows a detailed view of the tread, where the grooves include multiple elements in their arrangement on the groove surface. [Figure 3A] These are detailed diagrams of the tread grooves shown in Figures 1 and 2, along the AA distance. [Figure 3B] Three surfaces: Cross-sectional views of the groove along the AA distance shown in Figures 1 and 2, including two walls and a bottom. [Figure 4] This figure shows the shape of the elements in their arrangement on the groove surface according to one embodiment of the present invention. [Figure 5] This figure shows the relationship between the contact angle of a water droplet interacting with a surface and the volume of the element placed on the surface, when the element on the surface is new. [Figure 6] This figure shows the relationship between the contact angle of water droplets interacting with the surface and the volume of the element placed on the surface after the element has deteriorated over time. [Figure 7] This figure shows the combinations of data shown in Figures 5 and 6. [Figure 8] This figure shows the relationship between the true contact area of ​​the element and the contact angle formed between the water droplet and the surface containing the element. [Figure 9]This figure shows the arrangement of elements in a first cross-sectional plane according to one embodiment of the present invention. [Figure 10] A represents the corresponding void volume formed by the arrangement of elements shown in B, according to one embodiment of the present invention. [Figure 11] This figure shows the relationship between the contact angle of a water droplet interacting with a surface and the spacing parameter for the arrangement of elements on that surface. [Figure 12] This figure shows the relationship between the contact angle of a water droplet interacting with a surface and the porosity formed by the elements placed on that surface. [Figure 13] This figure shows the combination of data shown in Figures 11 and 12. [Figure 14] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D is a detailed view of the top of the second cross-sectional shape. [Figure 15] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D is a detailed view of the top of the second cross-sectional shape. [Figure 16] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D is a detailed view of the curved side of the second cross-sectional shape. [Figure 17] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D shows a detailed view of the transition to the side and top of the second cross-sectional shape. [Figure 18] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D shows a detailed view of the transition to the side and top of the second cross-sectional shape. [Figure 19]Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D shows a detailed view of the transition to the side and top of the second cross-sectional shape. [Figure 20] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element. Figure D shows a detailed view of the transition to the side and top of the second cross-sectional shape. [Figure 21] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element in one plane of the groove. Figure D shows the second cross-sectional shape of the element in the second plane of the groove. [Figure 22] Figure A shows an element on a groove surface according to one embodiment of the present invention. Figure B shows the first cross-sectional shape of the element. Figure C shows the second cross-sectional shape of the element in one plane of the groove. Figure D shows the second cross-sectional shape of the element in the second plane of the groove. Figure E shows the element in the second cross-sectional plane. [Figure 23] This figure shows a tire tread groove having the elements shown in Figure 22, which are oriented along the longitudinal axis in the circumferential direction. [Figure 24] This figure shows a tire tread groove having the elements shown in Figure 22, oriented along a longitudinal axis perpendicular to the circumferential direction. [Figure 25] Figures A to G show the first cross-sectional shape, second cross-sectional shape, and 3D shape of multiple elements according to various embodiments of the present invention. [Modes for carrying out the invention]

[0071] Figure 1 shows the tread 110 of a pneumatic tire 100, which includes a plurality of grooves 120 extending along the outer circumference of the tread 110 parallel to the circumferential direction 130.

[0072] Figure 2 shows details of the tread 110 shown in Figure 1, and the groove 120 includes multiple elements arranged along the groove surface, shown as dots within the groove 120.

[0073] Figures 3A and 3B show details of the groove 120 along the AA distance shown in Figures 1 and 2. Since the groove 120 has a U-shaped cross-section in an axis perpendicular to the circumferential axis, the groove 120 includes three groove surfaces 122: two walls 122b, 122c and a bottom 122a. The groove 120 has a width 124 perpendicular to the circumferential direction and a width 126 extending along the circumferential direction.

[0074] Figure 4 shows one embodiment of an element 410 in arrangement 400 on the groove surface 122. The element 410 may be described in terms of its cross-sectional shape in a first cross-sectional plane 420 and a second cross-sectional plane 430. Since the first cross-sectional plane 420 is a plane parallel to the groove surface, the first cross-sectional shape 425 of the element 410 is essentially the area of ​​the element's contact portion on the groove surface, thereby defining the width w of the element 410. Since the second cross-sectional plane 430 is a plane perpendicular to the groove surface and perpendicular to the circumferential axis, the second cross-sectional shape 435 of the element 410 defines the height h of the element 410. In this embodiment, the second cross-sectional shape 435 of the element 410 remains the same even if the second cross-sectional plane 430 is rotated by 90°. In other words, the element 410 is not elongated but point-like.

[0075] In the embodiment shown in Figure 4, the first cross-sectional shape 425 is square, and the second cross-sectional shape 435 is a truncated hyperbola with smooth, continuous curved sides and two parallel upper and lower edges. This is an example, but the element 410 may have a variety of different shapes, as can be seen from the following description.

[0076] Figure 5 shows the inverse relationship between the newly formed element volume and the contact angle formed between the static water droplet and the groove containing multiple elements 410.

[0077] As can be seen from Figure 5, as the element volume increases, the contact angle formed between element 410 and the static water droplet decreases, and for example, the hydrophobicity of the surface gradually decreases. As can be seen from the trend shown in Figure 5, eventually the element volume reaches a volume at which further increases in volume do not lead to a significant decrease in the contact angle, and for example, the functional relationship plateaus at approximately 136 degrees in the data shown in Figure 5. This is thought to be because, when the volume becomes very large, the surface becomes essentially continuous from the perspective of the element, and the contact angle approaches the contact angle that would have been observed if there were no element.

[0078] As shown in Figure 5, in order to obtain a groove surface 122 that exhibits good hydrophobicity, an element 410 with the smallest element volume is desirable, for example, 0.1 mm. 3 It is clear that the structure will approach a needle-like shape with a volume less than [amount missing].

[0079] Figure 6 shows the same relationship as shown in Figure 5 (for example, the relationship between element volume and the contact angle formed between a static water droplet and multiple elements), but it is for an aged surface rather than a new surface (as shown in Figure 5). As can be seen from the data in Figure 6, the element volume is 0.15 mm 3 Below this level, the contact area formed between the static water droplet and the element 410 of the present invention decreases rapidly (for example, hydrophobicity decreases).

[0080] The data points shown in Figure 6 directly correspond to the data points shown in Figure 5. For example, data point A in Figure 5 and A' in Figure 6 correspond to element 410, which is approximately 0.15 mm. 3 It has a volume of when newly formed (Figure 5), and when element 410 deteriorates over time, 75% of its material volume is lost, approximately 0.03 mm. 3 The contact angle for the same element 410 is measured for two different periods, when it has a volume (Figure 6).

[0081] Figure 7 shows data combined from Figures 5 and 6, illustrating how the relationship between element volume and the contact angle formed with static water droplets changes with element volume.

[0082] Figures 5, 6, and 7 show that elements 410, which have a smaller volume when new, are more affected by aging degradation in their hydrophobicity. Elements with smaller volumes (e.g., data points A / A', B / B', and C / C') initially exhibit the highest hydrophobicity (Figure 5), but their hydrophobicity decreases more rapidly than that of larger volumes. Thus, the effects of aging degradation and the hydrophobicity of surface 122 when new present conflicting requirements for element volume.

[0083] On the other hand, when new, the element volume is larger (for example, 0.5 mm as shown by data points D and E). 3 However, because the effects of aging are small, the change in hydrophobicity after aging is small (as shown by data points D' and E'). For example, Figure 6 shows that after aging, D' and E' of element 410 maintain approximately the same hydrophobicity (e.g., contact angle with water) even after approximately 75% of the element volume has been lost.

[0084] From Figure 7, 0.1 mm 3 It can be seen that elements 410 with a volume of less than 0.1 mm² suffer a dramatic decrease in contact angle after the aging of the tread 110. Therefore, the element volume is 0.1 mm². 3 Larger is beneficial.

[0085] The inventors understood that maximizing the volume of element 410 is important to improve resistance to aging and to maintain hydrophobicity even as the tire tread ages. The object of the present invention is therefore to provide an arrangement (e.g., pattern) for the groove surface 122 that maximizes the element volume while minimizing the contact area (and thus the contact angle) between element 410 and water droplets.

[0086] The solution envisioned by the present invention is to provide an element 410 having a base wider than its top, including, for example, inclined sides and / or curved or angled top surfaces (e.g., filleted sides, e.g., chamfered, e.g., sloped). The top surface of each element may be considered to represent its true contact area with water droplets in contact with the groove.

[0087] Figure 8 shows the relationship between the true contact area of ​​element 410, normalized for a columnar surface including a flat top, and the contact angle formed with a static water droplet. Thus, it will be understood that 100% surface area represents the structure of the columnar element with straight edges and the flat top surface (including, for example, a second cross-sectional shape of a rectangle or square). Consequently, the true contact area decreases as the corners of the cross-sectional shape at the surface in contact with the water droplet are rounded and the flat top gradually decreases.

[0088] As described above, as the degree of rounding of the corners of the element's second cross-sectional shape increases and the contact area decreases, the contact angle increases (for example, the hydrophobicity of the upper surface gradually increases).

[0089] The inventors therefore understood that by rounding or angling the sides of the element shape, a surface with desirable hydrophobicity can be obtained while maintaining a large element volume that improves resistance to aging degradation.

[0090] Figure 9 shows a cross-section (in a first cross-sectional plane 420 parallel to the groove surface) of an element pattern according to one embodiment of the present invention. In the illustrated pattern (e.g., a cubic pattern), element 411 is shown to have both a first nearest element 412 and a second nearest element 413, where the first nearest element has a spacing distance s shorter than the second nearest element spacing s'. In the illustrated cubic pattern, the second nearest element 413 defines a square around a central element 411 (e.g., the central element 411 is located at the center of the square), and the first nearest element 412 is located along the midpoint of the side of the square defined by the second nearest element 413.

[0091] The nearest neighbor spacings s, s' are defined as the distance between the centers of the first cross-sectional shapes of the elements 411, for example, the distance between the center of the first cross-sectional shape of the central element 411 and the center of the cross-sectional shapes of the first and / or second nearest neighbor elements.

[0092] Figure 10B shows a three-dimensional representation of the groove surface 122 and (for example) a plurality of conical elements 410 in a protruding arrangement on the groove surface 122. In this example, the arrangement includes a cubic pattern. The total volume of the elements 410 in the arrangement is the sum of (1 / 3)Ah for all the conical elements 410, where A is the area of ​​the base on the groove surface 122 and h is the height of the conical elements 410. Figure 10A shows a three-dimensional void volume 415 formed as a negative volume of the total element volume, for example, the void volume is the volume formed by the space between the elements 410. As shown in Figure 10A, the void volume 415 does not occupy the same volume or space as the total element volume, and the void volume 415 may be considered to fit around the elements 410 and form an actual volume up to height h across the groove surface 122. For example, the void volume and element volume have a key-and-key fit. It will be understood that the void volume 415, when combined with the total element volume, does not have to completely fill the available volume of the groove (for example, the groove shown in Figures 3A and 3B).

[0093] Figure 11 shows the functional relationship (in millimeters) between the contact angle formed between a static water droplet and a plurality of elements 410 according to one embodiment of the present invention, and the space between the elements 410. As can be seen from the data shown, as the void area decreases, for example, the spacing s between the elements 410 decreases, and the contact angle between the static water droplet and the elements 410 becomes smaller. Thus, the inventors have surprisingly found that it is advantageous to increase the void volume between the elements 410 according to the present invention.

[0094] Figure 12 shows the functional relationship between the contact angle formed between a static water droplet and a plurality of elements 410 according to one embodiment of the present invention, and the porosity of the element pattern arranged on the surface. Similar to Figure 11, it can be seen that as the porosity increases and the elements 410 are gradually spaced apart, the contact angle increases and the hydrophobicity of the surface increases.

[0095] From both Figures 11 and 12, it can be seen that the relationship between the contact angle and the one-dimensional and three-dimensional space between elements on the surface is sinusoidal. Therefore, it can be understood that it is preferable to select the spacing between elements and the element volume that allows for the optimal porosity.

[0096] Figure 13 shows how the optimization between porosity and element volume is determined by combining the data from Figures 12 and 6. As can be seen from Figure 13, the optimal range between porosity and element volume can be obtained by determining where the curve corresponding to the relationship between porosity and contact angle intersects with the curve corresponding to the relationship between element volume and contact angle. Therefore, in the example shown in Figure 13, the optimal range is a porosity of 50% to 65% and a diameter of 0.2 to 0.6 mm. 3 It may be determined that the pattern includes the element volume of the element.

[0097] Figures 14 to 22 show various embodiments of the element shape in various cross-sections and angles according to several embodiments of the present invention. All elements depicted herein have a height h of 0.6 mm, as just one example.

[0098] Figure 14A shows element 410a on groove surface 122 according to one embodiment of the present invention, having a first nearest neighbor spacing s of 1.2 mm. Figure 14B shows first cross-sectional shape 425a of element 410a on first cross-sectional plane 420, which is a square with a width w of 0.6 mm. Figure 14C shows second cross-sectional shape 435a of element, which is an irregular hexagon with two sets of parallel sides and two chamfered corners, for example, the second cross-sectional shape is substantially a quadrangular prism with a chamfered apex (i.e., two chamfered corners between the sides and the apex). Figure 14C also shows that the width w at the bottom of the second cross-sectional shape 435a is greater than the corresponding width w' at the apex of the second cross-sectional shape. Figure 14D shows detail of one of the chamfered corners, which is cut at a 45° angle with respect to the side and top of the shape, and the chamfer depth is 0.15 mm.

[0099] Figures 15A-D show elements 410b on the groove surface 122. The elements shown in Figure 15 are substantially identical to those shown in Figure 14, except that instead of being chamfered (as shown in Figure 14), they have rounded (e.g., filleted) top corners with a radius of curvature of 0.15 mm. However, because the radius of curvature is equal to the depth of the chamfer (e.g., 0.15 mm), the contact area of ​​the flat top surface is the same for both elements shown in Figures 14 and 15. The second cross-sectional shape 435b shown in Figure 15C is columnar with a filleted top, and it can be seen that the width w at the bottom of the second cross-sectional shape 435b is greater than the corresponding width w' at the top of the second cross-sectional shape 435b.

[0100] Figure 16 shows an element 410c on the groove surface 122 having a square first cross-sectional shape 425c with a first nearest neighbor spacing of 1.2 mm and a width of 0.6 mm, similar to Figures 14 and 15. Unlike Figures 14 and 15, element 410c has a second cross-sectional shape 435c corresponding to a truncated hyperbola, having two parallel edges connected, for example, by two non-parallel concave curved edges. Figure 16C shows that the width w at the bottom of the second cross-sectional shape 435c is greater than the corresponding width w' at the top of the second cross-sectional shape 435c. Figure 16D shows that the curved side surface has a depth of 0.15 mm and the bottom of element 410c has a width of 0.3 mm (for example, the area of ​​the top surface of element 410c is one-quarter of the area of ​​the bottom).

[0101] Figure 17 shows element 410d on the groove surface 122, which is a combination of the elements shown in Figures 14 and 16. For example, the second cross-sectional shape 435d includes a truncated hyperbolic shape with a chamfered top, and the chamfer depth is 0.15 mm. The first cross-sectional shape 425d is a square with a width of 0.9 mm, and the width of the top surface (e.g., the square root of the surface area of ​​the element in contact with the water droplet) is 0.3 mm. Figure 17C shows that the width w at the bottom of the second cross-sectional shape 435d is greater than the corresponding width w' at the top of the second cross-sectional shape 435d.

[0102] Figure 18 shows element 410e on groove surface 122, which is a combination of elements shown in Figures 15 and 16, for example, the second cross-sectional shape 435e includes a truncated hyperbolic shape with a filleted upper end having a radius of curvature of 0.15 mm. The first cross-sectional shape 425e is a square with a width of 0.9 mm, and the width of the top surface (e.g., the square root of the surface area of ​​the element in contact with the water droplet) is 0.3 mm. C in Figure 18 shows that the width w at the bottom of the second cross-sectional shape 435e is greater than the corresponding width w' at the top of the second cross-sectional shape 435e.

[0103] Figure 19A shows element 410f on groove surface 122 according to one embodiment of the present invention, having a first nearest neighbor spacing s of 1.0 mm. Figure 19B shows first cross-sectional shape 425f of element 410f on first cross-sectional plane 420, which is a square with a width w of 0.6 mm. Figure 19C shows second cross-sectional shape 435f of element, which is a flattened parabola, for example, a parabola with a flattened apex having two parallel edges parallel to the groove surface 122 and two convex curved surfaces extending between the apex and the sides with a depth of 0.15 mm. Figure 19C shows that the width w at the bottom of the second cross-sectional shape 435f is greater than the corresponding width w' at the apex of the second cross-sectional shape 435f.

[0104] Figure 20 shows the same element 410g as shown in Figure 19, the only difference between the two embodiments being that the first nearest neighbor spacing s is 1.2 mm in Figure 20 (compared to 1.0 mm in Figure 19). C in Figure 20 shows that the width w at the bottom of the second cross-sectional shape 435g is greater than the corresponding width w' at the top of the second cross-sectional shape 435g.

[0105] Figures 14 to 20 illustrate elements that have an overall point-like shape, while Figures 21 and 22 show examples of elongated elements.

[0106] Figure 21 shows an element 410h in a groove surface 122 according to one embodiment of the present invention, having a first nearest neighbor spacing s of 0.4 mm and a second nearest neighbor spacing s' of 2 mm (shown in Figure 21B). Figure 21B shows the first cross-sectional shape 425h of the element 410h in a first cross-sectional plane 420h, which is a rectangular elongated strip having a width w of 0.2 mm and a length l of 1.8 mm. It will be understood that the longitudinal axis of the element may be oriented in any suitable and / or desired direction, for example, parallel or perpendicular to the circumferential direction of the tread.

[0107] Figures 21C and 21D show different second cross-sectional shapes of element 410h in two planes perpendicular to the groove surface 122. If element 410h is oriented along a longitudinal axis parallel to the circumferential direction, it will be understood that Figure 21D represents the second cross-sectional shape 435h. On the other hand, if element is oriented along a longitudinal axis perpendicular to the circumferential axis, Figure 21C represents the second cross-sectional shape 435h. In Figure 21D, the second cross-sectional shape is a rectangle with an aspect ratio of approximately 5. Although not shown, the top of the rectangle may be rounded or chamfered, as disclosed herein.

[0108] Figure 22 shows an element 410i in a groove surface 122 according to one embodiment of the present invention, having a first nearest neighbor spacing s of 0.4 mm and a second nearest neighbor spacing s' of 2 mm. Figure 22B shows the first cross-sectional shape 425i of the element 410i in a first cross-sectional plane 420, which is a rectangular elongated strip having a width w of 0.2 mm and a length l of 1.8 mm. It will be understood that the longitudinal axis of the element may be oriented in any suitable and / or desired direction, for example, parallel or perpendicular to the circumferential direction of the tread.

[0109] Figure 22C shows that the second cross-sectional shape of element 410i in one plane perpendicular to the groove surface 122 is rectangular. Figures 22D and E show that the second cross-sectional shape of element 410i in the other plane perpendicular to the groove surface 122 is trapezoidal. In Figures 22D and E, the second cross-sectional shape is a trapezoid with an aspect ratio of approximately 4. Although not shown, the apex of the trapezoid may be rounded or chamfered, as disclosed herein. Figures 22D and E also show that the width w at the bottom of the second cross-sectional shape 435i is greater than the corresponding width w' at the top of the second cross-sectional shape 435i.

[0110] Figures 23 and 24 show two possible orientations of the elements shown in Figures 21 and 22 on the groove surface. For example, the elongated rectangular elements may be oriented so that the longitudinal axis of the first cross-sectional shape is parallel to the outer circumference of the tire (Figure 23). Alternatively, the longitudinal axis of the first cross-sectional shape may be oriented perpendicular to the outer circumference of the tire, for example, extending from groove wall to groove wall and / or from the bottom to the tread surface.

[0111] Figures 25A-G show the first cross-sectional shape (left), second cross-sectional shape (center), and 3D shape (right) of several elements according to various embodiments of the present invention. All elements are shown having a width w defined for the first cross-sectional shape (left) and a height h defined for the second cross-sectional shape (center). Thus, it will be understood that the width w is defined as the minimum dimension of the first cross-sectional shape, and the height h is defined as the maximum extended dimension of the second cross-sectional shape.

[0112] Figure 25A shows an element having a square first cross-sectional shape and a flattened parabolic second cross-sectional shape (for example, an element with a shape similar to the elements shown in Figures 19 and 20).

[0113] Figure 25B shows an element having a rectangular first cross-sectional shape and a Gaussian second cross-sectional shape with a truncated or flattened tip, such as a Gaussian curve with a flat apex, or two parallel surfaces of different widths and a sinusoidal edge transitioning between them.

[0114] Figure 25C shows an element that resembles a rounded cone, having a first circular cross-sectional shape and a second parabolic cross-sectional shape (for example, with the tip cut off at the bottom).

[0115] Figure 25D shows an element having a first triangular cross-sectional shape and a second substantially triangular cross-sectional shape with a rounded apex, such that the three-dimensional shape is a rounded triangular pyramid.

[0116] Figure 25E shows an element having a hexagonal first cross-sectional shape and a parabolic second cross-sectional shape (for example, with the tip cut off at the bottom).

[0117] Figure 25 shows an element F having a circular first cross-sectional shape and a rectangular second cross-sectional shape, such that its three-dimensional shape is a cylinder.

[0118] Figure 25G shows an element having a triangular first cross-sectional shape and a rectangular second cross-sectional shape, such that the three-dimensional element shape is a triangular prism.

Claims

1. This is a tread for pneumatic tires, It includes multiple grooves, The groove is groove surface and Multiple elements arranged on the groove surface with space between them, Includes, Each of the aforementioned elements has a shape that defines its volume, and the shape is A first cross-sectional shape in a plane parallel to the groove surface, wherein the minimum dimension of the first cross-sectional shape defined on the groove surface is such that the width w of the bottom of the element is 0.1 mm ≤ w ≤ 3 mm, and A second cross-sectional shape in a plane perpendicular to the groove surface, wherein the maximum dimension of the second cross-sectional shape from the bottom to the top of the groove surface defines the height h of the element, where 0.1 mm ≤ h ≤ 3 mm, and the second cross-sectional shape is generally parabolic or hyperbolic. The aspect ratio obtained by dividing the height h by the width w is at least 1 and at most 30. Includes, The aforementioned arrangement is, The void volume in the space between the elements, A porosity of 0.5 to 0.75, defined as the ratio of the void volume to the total volume of the elements in the arrangement, Tread, including

2. The tread according to claim 1, wherein the second cross-sectional shape includes the width w and the height h, and the width w at the bottom of the second cross-sectional shape is greater than the corresponding width w' at the top of the second cross-sectional shape.

3. This is a tread for pneumatic tires, It includes multiple grooves, The groove is groove surface and Multiple elements arranged on the groove surface with space between them, Includes, Each of the aforementioned elements is: A first cross-sectional shape in a plane parallel to the groove surface, wherein the minimum dimension of the first cross-sectional shape defined on the groove surface is the first cross-sectional shape that defines the width w of the bottom of the element, A second cross-sectional shape in a plane perpendicular to the groove surface, wherein the maximum dimension of the second cross-sectional shape from the bottom to the top of the groove surface is defined by the second cross-sectional shape that defines the height h of the element. Having a shape that includes, The second cross-sectional shape includes the width w and the height h, wherein the width w at the bottom of the second cross-sectional shape is greater than the corresponding width w' at the top of the second cross-sectional shape, and the second cross-sectional shape is generally parabolic or hyperbolic. The second cross-sectional shape is a tread having a curved, filleted, rounded, or chamfered top.

4. The tread according to any one of claims 1 to 3, wherein the second cross-sectional shape generally tapers from the bottom to the top.

5. The tread according to claim 1 or 2, wherein the second cross-sectional shape includes a curved, filleted, rounded, or chamfered top.

6. The tread according to any one of claims 1 to 5, wherein the first cross-sectional shape has a length l greater than the width w.

7. The tread according to any one of claims 1 to 6, wherein the first cross-sectional shape is an elongated strip defining a length l that is much larger than the width w.

8. Each of the aforementioned elements is approximately 0.1 mm ３ A tread according to any one of claims 1 to 7, having a shape that defines a larger volume.

9. The tread according to any one of claims 1 to 8, wherein the arrangement of the plurality of elements is a regular pattern.

10. The tread according to any one of claims 1 to 9, wherein the elements are spaced apart from each other in the arrangement at typical or average intervals of 50 μm to 1.5 mm.

11. A method for creating a tread according to any one of claims 1 to 10, using molding technology.

12. A mold configured for producing the tread according to any one of claims 1 to 10.

13. A method for creating a tread according to any one of claims 1 to 10, using laser engraving technology.

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