Method for determining specifications of vulcanized rubber components and method for manufacturing rubber products

Abstract

To provide a method capable of more simply determining the specification of a vulcanized rubber member having a desired dynamic friction characteristic, and to provide a production method for a rubber product comprising the vulcanized rubber member having the specification determined by the above method.SOLUTION: A specification determining method is characterized by previously taking hold of a correlation CR of dynamic friction coefficient of a vulcanized rubber member 1 to an object surface 4 with the estimated parameter X calculated by the following formula (1); the estimated parameter X=R2 / (λxE'2xD4)...(1) (R in the formula is the diameter of protrusion on the object surface; λ is a wavelength of that surface; E' is a storage elastic modulus of the rubber member; and D is the external diameter of a rigid grain) and by determining the storage elastic modulus Eo' of the vulcanized rubber member 1 being a selection candidate and the external diameter Do of the rigid grain so that a dynamic friction characteristic of the vulcanized rubber member 1 estimated based on the storage elastic modulus Eo', external diameter Do, protrusion diameter Ro and wavelength λo of the object surface 4 and the estimated parameter X, satisfies a target value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for determining the specifications of a vulcanized rubber component and a method for manufacturing a rubber product, and more specifically to a method for more easily determining the specifications of a vulcanized rubber component having desired dynamic friction characteristics, and a method for manufacturing a rubber product including a vulcanized rubber component having specifications determined by this specification determination method. [Background technology]

[0002] Dynamic friction characteristics are important for some rubber products. For example, the dynamic friction characteristics of tires against the road surface are important, and the dynamic friction characteristics of brake pads against the brake disc are important. To understand these dynamic friction characteristics, dynamic friction tests have traditionally been conducted to measure the dynamic friction coefficient.

[0003] To improve dynamic friction characteristics, it is known that, for example, in tires, tread rubber is blended with rigid particles such as powdered eggshells or crushed seashells (see, for example, Patent Document 1). To select rubber specifications with desired dynamic friction characteristics, it is necessary to prepare many types of test samples with different rigid particles and rubber types and conduct dynamic friction tests. Therefore, there is room for improvement in order to more easily determine the specifications of vulcanized rubber components with desired dynamic friction characteristics. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-167410 Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a method for more easily determining the specifications of a vulcanized rubber component having desired dynamic friction characteristics, and a method for manufacturing a rubber product equipped with a vulcanized rubber component having specifications determined by this specification determination method. [Means for solving the problem]

[0006] To achieve the above-mentioned object, the present invention provides a method for determining specifications for a vulcanized rubber member, which comprises vulcanized rubber and a large number of rigid particles contained within the vulcanized rubber and has a contact surface that slides against a target surface during use. The method comprises the steps of: determining a correlation between the dynamic friction coefficient of the vulcanized rubber member against the target surface and an estimated parameter X calculated using the following equation (1); estimating the dynamic friction characteristics of the candidate vulcanized rubber member against the target surface to be applied based on the storage modulus Eo' of the candidate vulcanized rubber member, the outer diameter Do of the contained rigid particles, the protrusion diameter Ro and wavelength λo of the target surface to be applied, and the estimated parameter X; specifying the storage modulus Eo' and outer diameter Do so that the estimated dynamic friction characteristics satisfy a predetermined target value for the dynamic friction characteristics; and determining the specified storage modulus Eo' and outer diameter Do as the specifications of the candidate vulcanized rubber member. Estimated parameters X=R 2 / (λ·E' 2 D 4 )···(1) Here, R is the diameter of the protrusions on the target surface, λ is the wavelength of the target surface, E′ is the storage modulus of the vulcanized rubber member, and D is the outer diameter of the rigid particle.

[0007] The method for producing a rubber product of the present invention is characterized in that it produces a rubber product including the vulcanized rubber member having specifications determined by the above-mentioned method for determining specifications for a vulcanized rubber member. [Effects of the Invention]

[0008] In the method for determining specifications for a vulcanized rubber member of the present invention, once the storage modulus Eo' and outer diameter Do of the internal rigid particles of a candidate vulcanized rubber member, as well as the protrusion diameter Ro and wavelength λo of the target surface to which the member is to be applied, are known, these data and the correlation CR between the previously determined kinetic friction coefficient and the estimated parameter X can be used to estimate the kinetic friction characteristics of the candidate vulcanized rubber member relative to the target surface to which the member is to be applied. Therefore, since there is no need to perform a kinetic friction test each time the specifications of the candidate vulcanized rubber member or the target surface to which the member is to be applied change, the kinetic friction characteristics can be easily determined. The storage modulus Eo' and outer diameter Do are then specified so that the estimated kinetic friction characteristics satisfy a predetermined target value for the kinetic friction characteristics, and the specified storage modulus Eo' and outer diameter Do are determined as the specifications of the candidate vulcanized rubber member. As a result, the specifications of a vulcanized rubber member having the desired kinetic friction characteristics can be more easily determined.

[0009] In the method for producing a rubber product of the present invention, a vulcanized rubber member having desired dynamic friction characteristics is used as a part of the rubber product, thereby making it possible to obtain rubber products having dynamic friction characteristics suited to the conditions under which each rubber product is used. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an explanatory diagram illustrating a cross-sectional view of a vulcanized rubber member and a target surface. [Figure 2] 2 is an explanatory diagram showing a cross-sectional view of a sliding state between the vulcanized rubber member of FIG. 1 and a target surface. FIG. [Figure 3] FIG. 10 is a graph illustrating the correlation CR between the estimated parameters and the increase in the dynamic friction coefficient. [Figure 4] FIG. 2 is an explanatory diagram illustrating a flow of a procedure for estimating the dynamic friction characteristics of a vulcanized rubber member. [Figure 5] FIG. 10 is an explanatory diagram illustrating a process for calculating a dynamic friction coefficient. [Figure 6] FIG. 2 is an explanatory diagram illustrating a cross-sectional view of the right half of a tire manufactured using the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The method for determining specifications for a vulcanized rubber member and the method for manufacturing a rubber product according to the present invention will be described based on the embodiments shown in the drawings.

[0012] In this specification determination method, the specifications are determined so that the vulcanized rubber member 1 shown in FIG. 1 exhibits desired dynamic friction characteristics. In order to determine the specifications, the dynamic friction characteristics (dynamic friction coefficient μ D ) is estimated.

[0013] The vulcanized rubber member 1 comprises vulcanized rubber 2 and a large number of rigid particles 3 contained within the vulcanized rubber 2, and has a contact surface 1a that slides against a target surface 4 during use. In this embodiment, the lower end surface of the vulcanized rubber member 1 forms the contact surface 1a that comes into contact with and slides against the target surface 4. The type of rubber used for the vulcanized rubber 2 is not particularly limited, and it can be made of any of a variety of general-purpose rubber compositions.

[0014] The rigid particles 3 are particles or aggregates that are harder than the vulcanized rubber 2 and do not substantially deform even when a frictional force acts on them. Specific examples of the rigid particles 3 include aggregates of various silica, carbon, aluminum hydroxide, calcium carbonate, metal particles, etc.

[0015] The target surface 4 is uneven with many tiny protrusions. The distance between the protrusions is expressed as wavelength λ, the radius of the protrusions is expressed as protrusion diameter R, and the height of the protrusions (size of the unevenness) is expressed as amplitude a.

[0016] First, the dynamic friction force generated in the vulcanized rubber member 1 containing a large number of rigid particles 3 will be described.

[0017] 2, when the vulcanized rubber member 1 is pressed against the target surface 4 with a predetermined pressure to bring the contact surface 1a into contact with the target surface 4, the contact surface 1a is pressed into the target surface 4. More specifically, the contact surface 1a is pressed into the protrusions on the target surface 4 (the protrusions are embedded in the contact surface 1a).

[0018] In this state, the vulcanized rubber member 1 is moved relative to the target surface 4 so that the contact surface 1a slides against the target surface 4. The direction of the relative movement is the extension direction of the target surface 4, as shown by the arrow in Figure 2. The vulcanized rubber member 1 moves relative to the contact surface 1a while deforming the area near the contact surface 1a (the area surrounded by the dashed line), and a kinetic friction force is generated as a resistance force during this movement.

[0019] The rigidity of the area near the contact surface 1a is significantly different from that of the surrounding vulcanized rubber 2. Therefore, when the contact surface 1a is slid over the target surface 4, the hysteresis loss of the vulcanized rubber member 1 (the vulcanized rubber 2 in this area) becomes larger than when the rigid particles 3 are not present. As a result, heat generation is promoted around the contact surface 1a, and the kinetic friction force (kinetic friction coefficient μ D ) increases. This increase in dynamic friction caused by deformation in the area near the contact surface is called hysteresis friction, and is thought to occur mainly due to the collapse of aggregates such as silica compounded in the rubber. Recent research has revealed that in addition to the hysteresis loss caused by the collapse of aggregates mentioned above, the presence of rigid particles 3 in the rubber also increases the friction caused by deformation in the area near the contact surface.

[0020] The kinetic friction force (kinetic friction coefficient μ D Through various experiments and analyses by the inventors of the present application, it has been found that the degree of increase in the parameter X can be grasped using the estimation parameter X in the following equation (1). The present invention is characterized in that it utilizes this estimation parameter X. Estimated parameters X=R 2 / (λ·E' 2 D 4 )···(1) In equation (1), R is the protrusion diameter (mm) of the target surface 4, λ is the wavelength (mm) of the target surface 4, E' is the storage modulus (MPa) of the vulcanized rubber member 1, and D is the outer diameter (μm) of the rigid particle 3.

[0021] The storage modulus E' of the vulcanized rubber member 1 can be measured using various known measuring devices (viscoelasticity measuring devices). The measurement conditions for the storage modulus E' may be set to an initial strain of 10%, an amplitude of ±2%, a temperature of 0°C, and a frequency of 20 Hz, in accordance with the provisions of JIS K6394. As long as the measurement conditions are consistently the same, the respective conditions are not limited to these and can be slightly different.

[0022] The outer diameter D of the rigid particles 3 is the average particle diameter of each rigid particle 3. The size Rs of the particles (aggregates) can be calculated by fitting the scattering profile obtained by ultra-small angle X-ray scattering measurement (USAXS) to the Unified-Guinier function of the following equation (2): s The average particle diameter is defined as the outer diameter D. For rigid particles 3 having an outer diameter D of more than 1 μm, the outer diameter D is measured using an optical microscope or the like.

[0023] I(q)=Aexp(-(q 2 Rgg 2 ) / 3)q -p +Bexp(-(q 2 Rgg 2 ) / 3)+Cexp(-(q 2 Rgg 2 ) / 3)×{erf(q·Rss / 6 1 / 2 )} 3Dm ·q -Dm +Dexp(-(q 2 Rgg 2 ) / 3)×E{erf(q·Rss / 6 1 / 2 )} 3(2d-Ds) ·q -(2d-Ds) ···(2) Here, q is the wavenumber, I(q) is the scattering intensity at wavenumber q, A, B, C, D, and E are constants (note that these constants D and E are different values ​​from the outer diameter D and elastic modulus E' mentioned above), p is the exponent, Rss is the size of the particles (aggregates) forming the hierarchical structure, Rgg is the size of the higher-order aggregates, Dm is the mass fractal dimension, Ds is the surface fractal dimension, and d is the Euclidean dimension of the space.

[0024] The rigid particles 3 may be scattered throughout the entire vulcanized rubber member 1, and as in this embodiment, it is desirable that they are scattered evenly at least in the region on the contact surface 1a side of the vulcanized rubber member 1. In this embodiment, the rigid particles 3 are not exposed at all from the contact surface 1a, but they may be exposed.

[0025] Data such as the protrusion diameter R, wavelength λ, and amplitude a of the target surface 4 can be measured using various known devices (surface roughness measuring instruments). While the target surface 4 is depicted in a simplified form in Figure 1, the actual target surface 4 has a more complex shape. Therefore, the protrusion diameter R of the target surface 4 is determined by fitting a quadratic curve to the convex portion of the profile of the surface roughness measurement data, determining the radius from the fitted quadratic curve, and using the average of these radii as a representative value. Furthermore, the wavelength λ is determined by Fourier analysis of the profile of the surface roughness measurement data, and the wavelength at which the amplitude a is maximum is used as a representative value.

[0026] Figure 3 shows the dynamic friction coefficient μ D The correlation CR between the estimated parameter X and the coefficient of dynamic friction μ D This dynamic friction coefficient μ D The degree of increase in the coefficient of dynamic friction μ when the rigid particles 3 are present in the vulcanized rubber member 1 is compared to when the rigid particles 3 are not present. D In this embodiment, the dynamic friction coefficient μ D Therefore, in FIG. 3, when the rigid particles 3 are present in the vulcanized rubber member 1, the dynamic friction coefficient μ D The larger the value, the higher the data is plotted, indicating that there is no difference between the two at the origin of the vertical axis. The vertical axis represents the coefficient of kinetic friction μ D In the present invention, the coefficient of dynamic friction μ D is measured in accordance with the test method specified in JIS K7125, but in order to eliminate the influence of adhesive friction, the value obtained by measuring with a lubricant interposed between the contact surface 1a and the target surface 4 is used.

[0027] Dynamic friction coefficient μ in Figure 4 D According to the correlation CR between the estimated parameter X and the coefficient of dynamic friction μ D In other words, when the value of the estimated parameter X is approximately 1 or less, the dynamic friction coefficient μ D The increase in the coefficient of dynamic friction μ D When the value of the estimated parameter X is approximately greater than 1, the coefficient of dynamic friction μ D It can be seen that increases linearly.

[0028] When the estimated parameter X exceeds the boundary point (the value is approximately 1), it increases as the storage modulus E' decreases, the outer diameter D of the rigid particle 3 decreases, the protrusion diameter R increases, and the wavelength λ decreases, and the kinetic friction coefficient μ D The reason for this is that the smaller the storage modulus E', the more easily the vulcanized rubber 2 deforms, and therefore the more easily the rigid particles 3 penetrate into the irregularities of the target surface 4, and also the smaller the outer diameter D of the rigid particles 3, the larger the protrusion diameter R, and the shorter the wavelength λ, the more easily the rigid particles 3 penetrate into the irregularities of the target surface 4, and the greater the hysteresis loss of the vulcanized rubber member 1 (vulcanized rubber 2).

[0029] In the present invention, the dynamic friction coefficient μ of the vulcanized rubber member 1 with various specifications (the specifications of the vulcanized rubber 2 and the specifications of the rigid particles 3 are varied) against the target surface 4 with various specifications (the projection diameter R and the wavelength λ are varied) D The data obtained by measuring the coefficient of dynamic friction μ of the vulcanized rubber member 1 shown in FIG. D The correlation CR between the estimated parameter X and the parameter X is determined in advance. This correlation CR data is input to and stored in a computing device such as a computer.

[0030] Then, by the procedure illustrated in FIG. 4, the dynamic friction characteristics (dynamic friction coefficient μ DThe data required to estimate this dynamic friction characteristic are the storage modulus Eo of the vulcanized rubber member 1 of the selection candidate, the outer diameter Do of the rigid particles 3, the protrusion diameter Ro of the target surface 4 to be applied, the wavelength λo, and the correlation CR described above that is known in advance.

[0031] Therefore, using the vulcanized rubber member 1 that is a candidate for selection, the storage modulus Eo and the outer diameter Do of the rigid particles 3 are determined. These data are measured and determined using the method described above. In addition, the projection diameter Ro and wavelength λo are determined using the target surface 4 to which the material is applied. These data are also measured and determined using the method described above.

[0032] Next, using the data on the storage modulus Eo, the outer diameter Do of the rigid particles 3, the protrusion diameter Ro, and the wavelength λo, and the data on the correlation CR previously determined, the dynamic friction characteristics (dynamic friction coefficient μ D ) is estimated. The data of the determined storage modulus Eo, outer diameter Do of the rigid particle 3, protrusion diameter Ro, and wavelength λo are input into a calculation device. The calculation device calculates the estimated parameter X based on the input data.

[0033] Next, as shown in FIG. 5, the calculation device substitutes the calculated value of the estimated parameter X into the data of the correlation CR stored in advance to calculate the dynamic friction coefficient μ D When grasping the data of the correlation CR, the dynamic friction coefficient μ of the vulcanized rubber member 1 with various specifications against the target surface 4 with various specifications is calculated. D The data obtained when measuring the coefficient of dynamic friction μ D Therefore, from these existing data, the dynamic friction coefficient μ D The standard data for the degree of increase (standard dynamic friction coefficient μ D ) and taking into account the calculated increase in this data, the dynamic friction characteristics (dynamic friction coefficient μ D ) can be estimated. Dmay be obtained by new measurement.

[0034] Here, the estimated dynamic friction characteristics (dynamic friction coefficient μ D ) is the dynamic friction characteristic (dynamic friction coefficient μ D The storage modulus Eo' and outer diameter Do are specified so as to satisfy the target values ​​of the dynamic friction characteristics (dynamic friction coefficient μ D ) does not satisfy the target value, at least one of the storage modulus Eo' and the outer diameter Do of the vulcanized rubber member 1 of the selection candidate is changed, and the dynamic friction characteristics (dynamic friction coefficient μ D ) is estimated.

[0035] Then, the estimated dynamic friction characteristics (dynamic friction coefficient μ D ) satisfy the target values, the storage modulus Eo' and the outer diameter Do are identified. The identified storage modulus Eo' and the outer diameter Do are determined as the specifications of the vulcanized rubber member 1 as selection candidates. The number of selection candidates for the specifications of the vulcanized rubber member 1 to be determined is not limited to one, and may be multiple.

[0036] According to this embodiment, if the storage modulus Eo' and the outer diameter Do of the internal rigid particles of the vulcanized rubber member 1 of the selection candidate, and the protrusion diameter Ro and wavelength λo of the target surface 4 to which the member is applied are known, these data and the previously known data of the correlation CR can be used to determine the dynamic friction characteristics (dynamic friction coefficient μ D Therefore, it is not necessary to perform a dynamic friction test every time the specifications of the vulcanized rubber member 1 or the specifications of the target surface 4 to which it is applied change. This significantly reduces the number of work steps, making it possible to easily grasp the dynamic friction characteristics.

[0037] In other words, since the dynamic friction characteristics of a wider range of specifications of the vulcanized rubber member 1 can be grasped in a short period of time, the specifications of the vulcanized rubber member 1 having the desired dynamic friction characteristics can be selected more accurately and efficiently depending on the specifications of the target surface 4 to which it is applied.

[0038] The data for the storage modulus Eo, outer diameter Do, projection diameter Ro, and wavelength λo do not have to be actually measured, and may be virtual data. That is, the present invention can be used to determine the dynamic friction characteristics of the vulcanized rubber member 1 based on the set values ​​for the storage modulus Eo, outer diameter Do, projection diameter Ro, and wavelength λo.

[0039] Then, the storage modulus Eo' and the outer diameter Do are specified so that the estimated dynamic friction characteristics meet the preset target values ​​of the dynamic friction characteristics, and the specifications of the vulcanized rubber member 1 are determined. If the vulcanized rubber member 1 meets the determined storage modulus Eo' and outer diameter Do, it will have the desired dynamic friction characteristics (dynamic friction coefficient μ D ) Therefore, the specifications of the vulcanized rubber member 1 having the desired dynamic friction characteristics can be determined more easily. Next, the vulcanized rubber member 1 having the determined specifications is manufactured, and the dynamic friction characteristics are actually measured to confirm whether or not the desired dynamic friction characteristics are achieved.

[0040] Examples of the vulcanized rubber member 1 include tire components (such as tread rubber), brake pads, seals (packing), etc. Therefore, the above-described method for determining specifications will greatly contribute to the development of tires, brake pads, seals, etc. with excellent performance.

[0041] In the method for manufacturing a rubber product of the present invention, a rubber product is manufactured that includes a vulcanized rubber member 1 having specifications determined by the above-described method for determining specifications of a vulcanized rubber member 1. That is, the rubber product is manufactured by providing a desired dynamic friction characteristic (dynamic friction coefficient μ) to a target surface 4 to which the rubber member 1 is applied. D The vulcanized rubber member 1 having the specifications determined to have the above properties is used as a part of the rubber product to manufacture the rubber product.

[0042] 6, if the rubber product to be manufactured is a tire T, the vulcanized rubber member 1 is used as tread rubber. The tire T may be manufactured by a known method, and the vulcanized rubber member 1 having specifications determined by the above-described specification determination method is simply used as the tread rubber.

[0043] In this tire T, a large number of rigid particles 3 are scattered at least in the vicinity of the contact surface 1a of the tread rubber (vulcanized rubber member 1), and therefore the tire T exhibits excellent dynamic friction characteristics. The rigid particles 3 may be scattered throughout the tread rubber (vulcanized rubber member 1). For example, if the target surface 4 to be applied is set to an ice surface, a snow surface, or the like, a tire T can be manufactured that has dynamic friction characteristics suited to these target surfaces 4. In this way, according to the method for manufacturing a rubber product of the present invention, rubber products having dynamic friction characteristics suited to the use conditions of each rubber product can be obtained.

[0044] Dynamic friction coefficient μ of vulcanized rubber member 1 D To increase the value of the estimated parameter X to improve grip performance, for example, it is preferable to increase the value of the estimated parameter X to more than 1, according to the data of the correlation CR shown in Fig. 5. Therefore, the specifications of the vulcanized rubber member 1 as a selection candidate should be as follows:

[0045] The storage modulus Eo' is set, for example, in the range of 30 MPa or less, more preferably 15 MPa or less. The lower limit of the storage modulus Eo' is, for example, about 5 MPa. The storage modulus Eo' can be varied by changing the type of rubber in the vulcanized rubber 2 or by changing the types and amounts of compounding agents blended into the vulcanized rubber 2. Those skilled in the art will understand how much the storage modulus Eo' changes depending on the type of rubber and the types and amounts of compounding agents used, and will therefore be able to obtain a vulcanized rubber member 1 with a desired storage modulus Eo' without extensive trial and error.

[0046] The outer diameter Do of the rigid particles 3 is set smaller than the projection diameter Ro, for example, in the range of 0.010 μm to 0.100 μm, more preferably 0.010 μm to 0.030 μm. The number density (particles / cm 3 ) is, for example, 10 14 Over 10 18 Less than or equal to 10, more preferably 16 Over 10 17 Set it to the following range:

[0047] The specifications of the target surface 4 to be applied are not particularly limited and vary depending on the use of the vulcanized rubber member 1. However, the protrusion diameter Ro is, for example, in the range of 0.1 mm or more, more preferably 1.0 mm or more. The wavelength λo is, for example, in the range of 3.0 mm or less, more preferably 1.5 mm or less.

Example

[0048] A vulcanized rubber member as illustrated in FIG. 1 was manufactured, and the coefficient of kinetic friction μ with respect to the target surface D and the correlation CR with the above-described estimated parameter X were grasped, and the results are shown in Tables 1 and 2. The specifications of the manufactured vulcanized rubber member and the specifications of the target surface are as shown in Tables 1 and 2. In Specifications 1 to 15, silica was used as the rigid particles, and the number density (number / cm 3 ) was on the order of 10 16 to 10 17 and was in a state of being generally evenly dispersed throughout the vulcanized rubber member. The storage modulus E’ was measured in accordance with the provisions of JIS K6394 under the measurement conditions as described in Paragraph 0021. In order to exclude the influence of adhesion friction as described in Paragraph 0026, the numerical value obtained by performing the measurement with a lubricant interposed between the contact surface 1a and the target surface 4 was used. For the outer diameter D, as described in Paragraphs 0022 to 0023, the aggregate size Rss was used. For the protrusion diameter R and the wavelength λ, the representative values as described in Paragraph 0025 were used. In Specification 15 of Table 2, R < D means that the outer diameter D is larger than the protrusion diameter R. In the table, the degree of increase in the coefficient of kinetic friction characteristics is, as described in Paragraph 0026, the difference in the numerical values of the coefficient of kinetic friction μ with respect to the case where no rigid particles are present when rigid particles are present in the vulcanized rubber member. D is the difference in the numerical values.

[0049]

Table 1

[0050]

Table 2

[0051] Specifications 1 to 8 in Table 1 are those in which the value of the estimated parameter X is greater than 1 and the dynamic friction coefficient μ D It can be seen that the coefficient of dynamic friction μ increases compared to when rigid particles are not present. D It can be seen that the coefficient of kinetic friction μ is essentially the same as when there are no rigid particles inside. In other words, the correlation CR that can be grasped based on the data in Tables 1 and 2 is similar to that in Figure 3, and the boundary point is when the value of the estimated parameter X is approximately 1. D Therefore, the coefficient of dynamic friction μ D It can be seen that making the numerical value of the estimation parameter X larger than approximately 1 is effective in increasing the value of the estimation parameter X. [Explanation of symbols]

[0052] 1. Vulcanized rubber material 1a Contact surface 2. Vulcanized rubber 3 Rigid particles 4 Target Surface T Tires (rubber products)

Claims

1. A method for determining specifications for a vulcanized rubber member that includes vulcanized rubber and a large number of rigid particles contained in the vulcanized rubber and has a contact surface that slides against a target surface during use, comprising: The correlation between the dynamic friction coefficient of the vulcanized rubber member with respect to the target surface and an estimated parameter X calculated by the following formula (1) is grasped in advance, a storage modulus Eo' and an outer diameter Do of the rigid particles contained therein, a protrusion diameter Ro and a wavelength λo of the target surface to be applied, and the estimation parameter X, based on which the dynamic friction characteristics of the vulcanized rubber member of the candidate selection candidate relative to the target surface to which the protrusion is applied are estimated; a storage modulus Eo' and an outer diameter Do are specified so that the estimated dynamic friction characteristics satisfy a predetermined target value for the dynamic friction characteristics; and the specified storage modulus Eo' and outer diameter Do are determined as the specifications of the vulcanized rubber member of the candidate selection candidate. Estimated parameters X = R 2 / (λ·E' 2 ・D 4 ) ... (1) Here, R is the diameter of the protrusions on the target surface, λ is the wavelength of the target surface, E′ is the storage modulus of the vulcanized rubber member, and D is the outer diameter of the rigid particle.

2. 2. The method for determining specifications of a vulcanized rubber member according to claim 1, wherein the rigid particles of the selected candidate vulcanized rubber member have an outer diameter Do of 0.010 μm or more and 0.100 μm or less.

3. The number density (number / cm) of the rigid particles of the vulcanized rubber member of the selection candidate 3 ) to 10 14 10 above 18 3. A method for determining specifications of a vulcanized rubber member according to claim 2, wherein:

4. The method for determining specifications of a vulcanized rubber member according to any one of claims 1 to 3, wherein the measurement conditions of the vulcanized rubber member to be selected as a candidate are such that the storage modulus Eo' is 30 MPa or less at an initial strain of 10%, an amplitude of ±2%, a temperature of 0°C, and a frequency of 20 Hz.

5. The method for determining specifications of a vulcanized rubber member according to any one of claims 1 to 4, wherein the projection diameter Ro on the target surface is set to 0.1 mm or more.

6. A method for manufacturing a rubber product, which manufactures a rubber product provided with a vulcanized rubber member having specifications determined by the method for determining specifications for a vulcanized rubber member according to any one of claims 1 to 5.

7. 7. The method for producing a rubber product according to claim 6, wherein the vulcanized rubber member having the determined specifications is a tread rubber, and the rubber product is a tire.

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