JP2016200563A - Evaluation method for sticking friction of rubber material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for precise evaluation of sticking friction of rubber material by using water containing surfactant.SOLUTION: A method for evaluation of sticking friction of rubber material against a frictional surface M comprises a first step of measuring a frictional coefficient at the time of spraying water containing surfactant on the frictional surface M when friction occurs to the rubber material on a first water-sprayed face, a second step of measuring a frictional coefficient at the time of spraying water containing no surfactant on the frictional surface M when friction occurs to the rubber material on a second water-sprayed face, and a third step of calculating the difference between the frictional coefficient measured in the first step and the frictional coefficient measured in the second step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for evaluating adhesion friction of a rubber material capable of evaluating the adhesion friction of a rubber material with high accuracy.

  It is known that the hysteresis friction due to the restoring force accompanying the deformation of the rubber material has a great influence on the friction coefficient of the rubber material. For this reason, conventionally, the friction coefficient of a rubber material has been evaluated by measuring only hysteresis friction.

  However, as a result of various studies by the inventors, it has been found that, in addition to hysteresis friction, the friction coefficient of rubber material also affects the friction coefficient of rubber material. Therefore, in order to accurately evaluate the friction coefficient of the rubber material, it is necessary to accurately evaluate the adhesion friction of the rubber material, but there is a problem that an evaluation method for the adhesion friction of the rubber material has not been established.

JP2012-93108A JP 2007-163142 A

  The present invention has been devised in view of the above problems, and is an evaluation that can evaluate adhesive friction of a rubber material with high accuracy on the basis of watering a surfactant-containing water on a friction surface. The main purpose is to provide a method.

  The present invention is a method for evaluating sticking friction when a rubber material is rubbed against a friction surface, wherein the rubber material contains a surfactant-containing water in which a surfactant is contained in water. A first step of measuring a friction coefficient acting on the rubber material when it is rubbed on the first water sprayed surface, and the rubber material does not contain the surfactant in the water A second step of measuring a friction coefficient acting on the rubber material when water is rubbed on the second water spray surface sprayed on the friction surface; and the friction coefficient measured in the first step and the first step A third step of calculating a difference from the friction coefficient measured in two steps is included.

  In the method for evaluating adhesion friction of a rubber material according to the present invention, it is desirable that the relative speed of the rubber material with respect to the friction surface is 3 to 20 Km / h.

  In the method for evaluating adhesion friction of rubber materials according to the present invention, the surfactant preferably includes at least one of a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant. .

  In the method for evaluating adhesion friction of a rubber material according to the present invention, the surfactant-containing water preferably contains 1% by mass to 60% by mass of the surfactant.

  In the method for evaluating adhesion friction of a rubber material according to the present invention, the friction surface is preferably an asphalt road surface on which a vehicle travels.

  The method for evaluating adhesion friction of a rubber material according to the present invention measures the coefficient of friction that acts on the rubber material when the rubber material is rubbed on the first water spray surface in which surfactant-containing water is sprayed on the friction surface. 1st step, 2nd step which measures the friction coefficient which acts on rubber material when rubbing rubber material on the 2nd watering surface which sprinkled surfactant non-containing water on the friction surface, and 1st step A third step of calculating a difference between the friction coefficient measured in step 2 and the friction coefficient measured in the second step. In the first step, since the generation of adhesive friction is suppressed by the surfactant-containing water, the friction coefficient due to hysteresis friction is measured. In the second step, the coefficient of friction due to hysteresis friction and adhesive friction is measured with the surfactant-free water. For this reason, in the third step, an adhesion friction component is calculated. Therefore, in the method for evaluating the adhesion friction of a rubber material according to the present invention, the adhesion friction of the rubber material can be evaluated with high accuracy.

It is a perspective view of the friction testing machine for enforcing the evaluation method of adhesion friction of rubber material of the present invention. It is a bottom view of the friction tester of FIG. (A), (b) is a side view of a friction testing machine. (A) is a graph showing the friction coefficient-loss tangent of the rubber material when the surfactant is 6% by mass, and (b) is the friction coefficient-loss tangent of the rubber material when the surfactant is 1% by mass. It is a graph showing. (A) is a graph showing the friction coefficient-loss tangent of the rubber material when the surfactant is 60% by mass, and (b) is the friction coefficient-loss tangent of the rubber material when the surfactant is 70% by mass. It is a graph showing. It is a graph showing the friction coefficient-loss tangent of a rubber material when surfactant-free water is used.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The method for evaluating the adhesion friction of the rubber material of the present invention (hereinafter sometimes simply referred to as “evaluation method”) can be used either outdoors or indoors. In the present specification, the adhesive friction refers to friction caused by an adhesive that is peeled off from the rubber material when the rubber material is rubbed.

  As shown in FIG. 1, when the evaluation method is performed outdoors, the friction surface M that rubs the rubber material G is, for example, a road surface formed of asphalt material or concrete material on which the vehicle can travel. . When the evaluation method is performed indoors, for example, a pseudo road surface formed of asphalt material or concrete material can be adopted as the friction surface M.

  The evaluation method according to the present embodiment includes a preparation process K1 for preparing a friction tester 1 that causes the rubber material G to rub against the friction surface M (hereinafter simply referred to as “tester 1”), and a friction tester 1. And an evaluation step K2 for evaluating the adhesion friction of the rubber material G.

  In the preparation step K1 of the present embodiment, a known testing machine 1 is prepared. As the testing machine 1, various types can be adopted as long as it can perform a slip resistance test on a road surface or the like standardized as ASTM (American Materials Testing Association) standard test method 1911E. In the present embodiment, a DF tester manufactured by Nihon Sangyo Co., Ltd. is used.

  The friction tester 1 includes, for example, a tester main body 3 that rubs the rubber material G on the friction surface M, and a watering device 4 that makes the friction surface M wet.

  As shown in FIGS. 1 to 3, the testing machine main body 3 includes a moving means 5 that rotates and moves the rubber material G and a driving means 6 that drives the moving means 5 in this embodiment. The moving means 5 and the driving means 6 are covered with a casing 7 that protects them.

  The moving means 5 includes, for example, a circular and plate-like disk portion 8. The disc portion 8 has a lower side surface 8a facing the friction surface M side and an upper side surface 8b facing away from the lower side surface 8a. A rubber holder 10 having a known structure that holds the rubber material G in a replaceable manner is provided on the lower side surface 8a of the disk portion 8. In the present embodiment, three rubber holders 10 are provided at an equal pitch in the circumferential direction.

  The driving means 6 includes, for example, a support shaft 9 that rotatably supports the disc portion 8. The support shaft 9 of the present embodiment extends upward from the upper side surface 8 b of the disk portion 8.

  For example, a lifting device (not shown) that lifts and lowers the disk portion 8 and a rotating mechanism 11 that rotates the disk portion 8 in the circumferential direction are connected to the support shaft 9. The rubber material G is pressed onto the friction surface M by the lowering of the disc portion 8 by the lifting device. Thereby, a required ground load is given to the rubber material G. The rubber material G is continuously given a frictional force by the rotation of the disc portion 8 by the rotation mechanism 11. As the lifting device, for example, a known structure including a cylinder mechanism is preferable.

  The rotation mechanism 11 includes, for example, an electric motor 13 that rotationally drives the disk portion 8 via a bearing (not shown) that rotatably supports the support shaft 9. The rotation mechanism 11 preferably includes speed control means (not shown) such as an inverter for controlling the rotation speed of the electric motor 13 and thus the peripheral speed of the disk portion 8.

  For measuring the friction coefficient acting on the rubber material G, a measuring device (not shown) having a well-known structure is used. The measuring instrument of this embodiment includes an elastic body that is relatively displaced with respect to the rotational movement of the disk portion 8. Data relating to the amount of displacement of the elastic body and the load acting on the rubber material G are input to the arithmetic processing unit 15, for example, and the friction coefficient and the like are calculated. As the elastic body, for example, a spring-like one is desirable. As the arithmetic processing unit 15, for example, a personal computer or the like is desirable. Various measuring devices such as a load cell may be employed as the measuring device.

  The housing 7 is formed in a rectangular shape in plan view, for example, and includes an upper plate portion 7 a that covers the upper portion of the disc portion 8, a side plate portion 7 b that covers the side of the disc portion 8, and a lower portion of the disc portion 8. It includes an opening 7c for contacting the rubber material G and the friction surface M on the side.

  For example, a rubber seat 16 for stably setting the testing machine 1 on the friction surface M is provided at the bottom of the side plate portion 7 b of the housing 7.

  The watering device 4 includes, for example, a tank 4a that holds an aqueous solution, a watering nozzle 4b that sprays the aqueous solution onto the friction surface M, and a connecting pipe 4c that connects the tank 4a and the watering nozzle 4b via a valve 4d. It is out.

  In the present embodiment, the tank 4a is provided on the upper surface of the upper plate portion 7a of the housing 7. The tank 4a is not limited to such an aspect, and may be provided on the friction surface M, for example. Moreover, the watering nozzle 4b is attached to the side plate part 7b of the housing | casing 7 in this embodiment.

  Moreover, it is desirable that the watering device 4 includes a water amount adjuster (not shown) for adjusting the amount of water spray, that is, the water depth of the friction surface M. The water volume regulator employs a well-known structure, and is controlled by the arithmetic processing unit 15, for example.

  The evaluation process K2 includes a first step S1 to a third step S3. The first step S1 is a step of measuring a friction coefficient acting on the rubber material G when the rubber material G is rubbed on the first watering surface 20a (shown in FIG. 3B). The second step S2 is a step of measuring a friction coefficient acting on the rubber material G when the rubber material G is rubbed on the second water spray surface 20b. The third step S3 is a step of calculating a difference between the friction coefficient measured in the first step S1 and the friction coefficient measured in the second step S2. The first water spray surface 20a is a state in which surfactant-containing water in which a surfactant is contained in water is sprayed on the friction surface M. Further, the second watering surface 20b is a state in which surfactant-free water that does not contain a surfactant in water is sprayed on the friction surface M.

  As shown in FIG. 3A, in the first step S1, first, the rubber material G is attached to the rubber holder 10, and the testing machine 1 is placed on the friction surface M. At this time, in this embodiment, the disc part 8 is lifted upward by the lifting device, and the rubber material G and the friction surface M are kept in a non-contact state. In the first step S1, surfactant-containing water is supplied to the tank 4a.

  As the rubber material G held by the rubber holder 10, various rubber materials can be used. For example, when evaluating the adhesion friction of a tire, it is desirable to use the rubber material G by cutting it out from a tread rubber of a vulcanized tire. The size of the rubber material G may be created in accordance with the size of the disk portion 8. For example, the circumferential length L (shown in FIG. 2) is 5 to 15 mm, and the radial width W is Those having a thickness of 5 to 15 mm and a thickness of 2 to 5 mm are desirable. As the rubber material G, various materials such as vulcanized rubber previously processed into a sheet shape can be adopted.

  Next, the disk portion 8 of the test machine 1 is rotated at a specified speed by driving the electric motor 13. At this time, as shown in FIG. 3B, the surfactant-containing water in the tank 4a is sprinkled from the watering nozzle 4b to the friction surface M, and the friction surface M is formed as the first watering surface 20a. It is preferable that the surfactant-containing water is sprinkled with a predetermined amount of water by the water amount regulator.

  Next, for example, the disk portion 8 is lowered by the lifting device, and the rubber material G and the first water spray surface 20a are pressed with a predetermined ground pressure, whereby a frictional force is generated in the rubber material G. Next, the friction coefficient acting on the rubber material G is measured by the measuring means.

  In such a first step S1, the adhesive (not shown) peeled off from the rubber material G due to friction is smoothly removed from between the rubber material G and the friction surface M due to the viscosity of the surfactant-containing water. . Accordingly, the friction coefficient measured in the first step S1 can measure the friction coefficient mainly due to only the hysteresis friction without sticking friction due to the sticking material.

  In 1st step S1 of this embodiment, after contact with rubber material G and the 1st sprinkling surface 20a, the electric motor 13 of the drive means 6 is stopped and the disc part 8 is rotated by inertial force. The measurement of the friction coefficient is performed, for example, from the time of contact between the rubber material G and the first sprinkling surface 20a until the rubber material G naturally stops rotating due to frictional force.

  A variety of surfactants can be used. For example, a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant can be used to effectively exhibit the above-described action. It is desirable to include at least one of the agents.

  The surfactant-containing water desirably contains 1% by mass to 60% by mass of the surfactant. When the surfactant is less than 1% by mass, the viscosity of the surfactant-containing water becomes small, and there is a possibility that the above-mentioned adhesive cannot be removed smoothly from between the rubber material G and the friction surface M. When the surfactant exceeds 60% by mass, resistance due to the viscosity of the surfactant-containing water increases, and the friction coefficient may not be measured with high accuracy.

  Next, the second step S2 is performed. In the second step S2, first, a new rubber material G is attached to the rubber holder 10, and the tank 4a is filled with surfactant-free water. Since the surfactant-containing water is sprayed on the friction surface M measured in the first step S1, it is desirable that the second step S2 is performed at a place different from the first step S1.

  As the surfactant-free water, for example, tap water is used. On the second sprinkling surface 20b on which such surfactant-free water has been sprinkled, the adhesive material of the rubber material G is difficult to be removed from between the rubber material G and the friction surface M. For this reason, in the second step S2, a friction coefficient resulting from hysteresis friction and adhesive friction is measured.

  Since the method for measuring the friction coefficient in the second step S2 is the same as the method for measuring the friction coefficient in the first step S1, the description thereof is omitted.

  The relative speed of the rubber material G with respect to the friction surface M in the first step S1 and the second step S2 is preferably about 3 to 20 km / h in order to wear the friction coefficient with high accuracy. When the relative speed of the rubber material G is less than 3 km / h, the rubber material G is easily caught on the uneven portion of the friction surface M, and the friction coefficient may not be measured with high accuracy. When the relative speed of the rubber material G exceeds 20 km / h, the adhesive material is removed from between the rubber material G and the friction surface M even on the second sprinkling surface 20b. Measurement may not be possible.

  Next, the third step S3 is performed. The third step S3 is preferably calculated by the arithmetic processing unit 15, for example. In the present embodiment, in the first step S1, a friction coefficient due to hysteresis friction is measured. In the second step S2, a friction coefficient caused by hysteresis friction and adhesive friction is measured. For this reason, in the third step S3, the adhesive friction component is calculated with high accuracy. Therefore, in the method for evaluating the adhesion friction of a rubber material according to the present invention, the adhesion friction of the rubber material can be evaluated with high accuracy.

  In the measurement method according to the first step S1 of the present embodiment, it is proved by the following experimental example that the friction coefficient due to the hysteresis friction can be measured. That is, this is proved by comparing the measurement result of the coefficient of friction acting on the rubber material G with the measurement result of the loss tangent (tan δ) of the rubber material G using the measurement method in the first step S1. The hysteresis friction is proportional to the loss tangent (tan δ).

<Friction test by friction tester>
Six types of rubber materials (rubber a to rubber f) having different compositions were prepared, and the friction coefficient was measured by the evaluation method of the present invention using a DF tester manufactured by Nihon Sangyo Co., Ltd. The result is displayed as an index with the friction coefficient of the rubber a being 100 at each surfactant concentration.
Surfactants (nonionic surfactants and anionic surfactants): Kao Co., Ltd. dishwashing detergent kyutut (registered trademark)
Relative speed of rubber material against friction surface: 7km / h
The test results are shown in Table 1.

<Loss tangent of rubber material (tanδ)>
The loss tangent of the rubber materials (rubber a to rubber f) used in the friction test was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd.
Initial strain 10%
Dynamic strain 2%
10Hz frequency
Table 2 shows the test results.

  Graphs showing the relationship between the rubber friction coefficient and the loss property of the rubber material using the test results are shown in FIGS. The horizontal axis of each figure shows friction loss. The vertical axis of each figure shows the friction coefficient (index). 4 (a) to 5 (a) in which the surfactant is contained in the surfactant-containing water in an amount of 1% to 60% by mass, the surfactant is contained in the surfactant-containing water in an amount of 70% by mass. Compared with FIG. 5B and FIG. 6 of the surfactant-free water, the correlation between the loss tangent and the rubber friction well represents a proportional relationship. For this reason, it is understood that hysteresis friction can be measured with high accuracy by using a surfactant-containing water containing 1 to 60% by mass of a surfactant. In addition, it is estimated that the friction coefficient measured by 2nd step S2 is a friction coefficient resulting from hysteresis friction and adhesion friction.

  Further experiments were carried out by changing the rubber composition and using other preferred surfactants, and showed similar trends. Furthermore, although the relative speed of the rubber material with respect to the friction surface was changed at 3 to 20 km / h, the same result was obtained. Therefore, it can be understood that the adhesion friction can be measured with high accuracy by using the evaluation method of the present invention.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention can be changed and implemented in various aspects, without being limited to the said embodiment.

G rubber material M friction surface 20a first watering surface 20b second watering surface S1 first step S2 second step S3 third step

Claims (5)

A method for evaluating adhesive friction when a rubber material is rubbed against a friction surface,
First, a friction coefficient acting on the rubber material is measured when the rubber material is rubbed on a first water spray surface in which a surfactant-containing water in which a surfactant is contained in water is sprayed on the friction surface. 1 step,
A coefficient of friction acting on the rubber material is measured when the rubber material is rubbed on the second water spray surface where water which does not contain the surfactant in the water is sprinkled on the friction surface. A second step, and
A method for evaluating adhesion friction of a rubber material, comprising a third step of calculating a difference between the friction coefficient measured in the first step and the friction coefficient measured in the second step.   The method for evaluating adhesion friction of a rubber material according to claim 1, wherein a relative speed of the rubber material with respect to the friction surface is 3 to 20 km / h.   The method for evaluating adhesion friction of a rubber material according to claim 1 or 2, wherein the surfactant includes at least one of a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant.   The method for evaluating the adhesion friction of a rubber material according to any one of claims 1 to 3, wherein the surfactant-containing water contains 1% by mass to 60% by mass of the surfactant.   5. The method for evaluating adhesion friction of a rubber material according to claim 1, wherein the friction surface is an asphalt road surface on which a vehicle travels.

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