JP2015215314A - Rubber-chipping resistance performance evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily evaluating rubber-chipping resistance performance even on a rubber composition having high rubber-chipping resistance performance.SOLUTION: Provided is a rubber-chipping resistance performance evaluation method in which a strike piece 5 of a pendulum 4 in which the strike piece 5 is provided on an arm 9 supported by a shaft center i is made collide a front face Sa1 of a rubber test piece 2 supported by a support tool, for evaluating rubber-chipping resistance performance on the basis of drop energy of the pendulum 4 and a rubber-chipping state of the rubber test piece 2. The rubber test piece 2 is a rectangular block shape. The strike piece 5 of the pendulum 4 has a lower corner part Q. The lower corner part Q is made collide with the front face Sa1 during or immediately before or after vertical line passage when the arm 9 passes a vertical line X extending from the shaft center i. The rubber test piece 2 is configured so that, a hard bumper plate 13 embedded in the rubber test piece 2 and on a rear side separated from the front face Sa1 by distance L.

Description

  The present invention relates to a method for evaluating the resistance to rubber chipping with accuracy close to the evaluation of tire chipping in the market for rubbers of various compositions.

  As a method for evaluating the resistance to rubber chipping with an accuracy close to the evaluation of the rubber chipping of a tire in the market, the one disclosed in Patent Document 1 below is known. In this evaluation method, a pendulum striking piece is made to collide with a rubber test piece supported by a support, and the resistance to rubber chipping is evaluated from the drop energy of the pendulum and the state of rubber chipping generated in the rubber test piece. Is. In particular, the rubber test piece is formed in a rectangular block shape surrounded by front and rear surfaces, upper and lower surfaces, and both side surfaces, and a slit is formed on the front surface thereof.

JP 2012-251833 A

  However, in the evaluation method as described above, the impact applied to the rubber test piece by the striking piece is dispersed throughout the rubber test piece by elastic deformation of the rubber test piece. For this reason, for example, in the case of a rubber composition having high rubber chipping resistance, there is a possibility that rubber chipping does not occur in the rubber test piece and the rubber chipping performance cannot be evaluated.

  The present invention has been made in view of the above problems, and its main object is to provide a method capable of easily evaluating the resistance to rubber chipping even with a rubber composition having high resistance to chipping.

  According to the present invention, a pendulum is formed by colliding the striking piece of a pendulum provided with a striking piece on the other end of an arm pivotally supported by a horizontal axis on the front surface of a rubber test piece supported by a support. The rubber chipping resistance evaluation method evaluates the rubber chipping resistance performance from the falling energy of the rubber and the state of the rubber chipping of the rubber test piece, wherein the rubber test piece is a rectangle surrounded by the front and rear surfaces, the upper and lower surfaces, and both side surfaces The front surface of the pendulum is supported in parallel with the axial direction in the form of a block, and the striking piece of the pendulum has a lower corner portion where an opposing surface facing the front surface and a lower surface facing downward intersect at the time of collision, When the arm passes through the vertical line extending from the axial center or immediately after passing through the vertical line, the lower corner portion is made to collide with the front surface, and the rubber test piece is in the rubber test piece and from the front surface. Hard at the position with a distance L behind Wherein the impact receiving plate is embedded.

In the rubber chip resistance evaluation method according to the present invention, it is desirable that the impact plate has a Young's modulus of 1.0 × 10 ⁸ Pa or more.

  In the rubber chipping resistance evaluation method according to the present invention, it is desirable that the impact plate is a metal plate.

  In the rubber chipping resistance evaluation method according to the present invention, it is desirable that a collision position where the lower corner portion collides with the front surface has a height H from the upper surface of 1.0 to 5.0 mm.

  In the rubber chipping resistance evaluation method according to the present invention, it is desirable that the receiving plate has a buried depth D from the upper surface at the lower end of 1.4 mm or more of the height H.

  In the rubber chipping resistance evaluation method according to the present invention, the rubber chipping performance is determined by fixing the value of the pendulum drop energy and the distance L of the impact plate to a reference value, and the weight of the rubber chipping of the rubber test piece. It is desirable to evaluate using the size of as an index.

  In the rubber chipping resistance evaluation method according to the present invention, the rubber chipping performance is determined by fixing the value of the drop energy of the pendulum to a reference value, and setting the distance L of the impact plate at which no rubber chipping occurs in the rubber test piece. It is desirable to evaluate as an index.

  In the rubber chipping resistance evaluation method of the present invention, a hard impact plate is embedded in a rubber test piece at a position spaced a distance L from the front surface to the rear. For this reason, when the striking piece collides with the rubber test piece, the impact acting on the front surface of the rubber test piece is concentrated on the rubber portion between the front surface of the rubber test piece and the impact plate. Therefore, in the rubber chipping resistance evaluation method of the present invention, it is possible to easily generate rubber chipping even for a rubber composition having high rubber chipping resistance, with an accuracy close to the evaluation of tire chipping in the market. The rubber chipping resistance can be evaluated.

It is a front view of the testing apparatus used for the evaluation method of this embodiment. It is the perspective view to which the rubber test piece vicinity of FIG. 1 was expanded. It is a side view at the time of an impact piece colliding with a rubber test piece. It is a perspective view of the rubber test piece which rubber | gum lack generate | occur | produced. (A) is a top view of the rubber test piece of another aspect, (b) is a side view of the rubber test piece of another aspect.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a front view of a test apparatus 1 used for the rubber chipping resistance evaluation method of this embodiment. As shown in FIG. 1, a test apparatus 1 includes a support 3 that supports a rubber test piece 2, and a pendulum impact tool 6 that causes a striking piece 5 of a pendulum 4 to collide with the rubber test piece 2 to generate a rubber chip. It has.

  The support 3 is not particularly limited as long as it can support the rubber test piece 2 so as not to move when the striking piece 5 collides with the rubber test piece 2. For example, a so-called vise is used for the support 3 of the present embodiment.

  The pendulum impact tool 6 includes a pendulum 4, a support shaft 8 that pivotally supports the pendulum 4, and a stand 7 that supports the support shaft 8 horizontally. The pendulum 4 includes an arm 9 that is pivotally supported at one end by a support shaft 8 and that can swing around an axis i of the support shaft 8.

  The stand 7 of the present embodiment includes, for example, a base 7A installed on the floor surface and a column 7B rising from the base 7A. Further, the stand 7 of the present embodiment is provided with a display unit 10 that displays the swing angle α of the arm 9 with the vertical line X extending in the vertical direction from the axis i of the support shaft 8 as 0 °.

  The striking piece 5 of this embodiment is attached to the other end of the arm 9. The striking piece 5 includes a striking piece main body 5A on the front side that collides with the rubber test piece 2 and a weight portion 5B on the rear side thereof. For example, the weight 5B is configured such that its weight can be adjusted.

  FIG. 2 shows a perspective view in which the vicinity of the rubber test piece 2 of FIG. 1 is enlarged. As shown in FIG. 2, the striking piece main body 5A of the present embodiment has, for example, an axial width W1 of about 40 mm and a vertical height H1 of about 30 mm. A rectangular block shape having a right-angle length L1 of about 30 mm is shown.

  The striking piece main body 5A has a facing surface K1 facing the rubber test piece 2 at the time of collision, a lower surface K2 facing downward, and a lower corner portion Q where the facing surface K1 and the lower surface K2 intersect. It is desirable that the facing surface K1 and the lower surface K2 intersect at an angle θ of 45 to 100 °, and in this embodiment, an impact piece main body 5A having an angle θ of 90 ° is shown.

  The rubber test piece 2 is formed in a rectangular block shape surrounded by the front and rear surfaces Sa1 and Sa2, the upper and lower surfaces Sb1 and Sb2, and both side surfaces Sc. The rubber test piece 2 of the present embodiment has, for example, an axial width W2 of about 60 mm, a vertical height H2 of about 25 mm, and a length L2 perpendicular to the axial direction of 40 mm. The degree is shown.

  In the rubber test piece 2 of the present embodiment, for example, the lower surface Sb2, the lower portion of the front surface Sa1, and the rear surface Sa2 are held and supported by the support tool 3. The rubber test piece 2 is supported so that the front surface Sa1 is parallel to the opposing surface K1 of the striking piece 5. For example, the rubber test piece 2 is preferably supported on the side surfaces Sc and Sc and supported by the support 3, and the movement when the striking piece 5 collides is further suppressed.

  FIG. 3 shows a side view when the striking piece 5 collides with the rubber test piece 2. In the test apparatus 1 of the present embodiment, as shown in FIG. 3, the striking piece 5 of the pendulum 4 is caused to collide with the upper part of the front surface Sa <b> 1 of the rubber test piece 2 supported by the support 3, and the corner of the rubber test piece 2. Rubber cracks are generated in the portion P. More specifically, the lower corner portion Q of the striking piece 5 is caused to collide with the front surface Sa1 of the test piece 2 when the arm 9 passes through the vertical line X or immediately after passing through the vertical line. Thereby, after rubber | gum chipping generate | occur | produces in the corner part P of the rubber test piece 2, evaluation of rubber | gum chipping resistance is performed from the fall energy of the pendulum 4 and the rubber | gum chipping state of the rubber test piece 2. FIG.

  FIG. 4 shows a perspective view of the rubber test piece 2 in which rubber chipping has occurred. As shown in FIG. 4, the rubber chip state of the rubber test piece 2 is, for example, the maximum width in the axial direction of the portion where the rubber chip has occurred, the maximum depth from the upper surface Sb1, the maximum depth from the front surface Sa1, etc. In this embodiment, the weight of the missing rubber is evaluated as an index. In addition, the weight of the missing rubber is calculated from the weight measured by measuring the weight before and after the occurrence of the rubber missing in the rubber test piece 2, for example.

  As shown in FIG. 2, the rubber test piece 2 has a hard receiving plate 13 embedded therein. The impact receiving plate 13 is embedded at a position spaced a distance L from the front surface Sa1 to the rear surface Sa2 of the rubber test piece 2. For this reason, when the rubber test piece 2 and the impact piece 5 collide, the impact acting on the front surface Sa1 of the rubber test piece 2 is concentrated on the rubber portion between the front surface Sa1 of the rubber test piece 2 and the impact plate 13. Act. Therefore, the rubber chipping resistance evaluation method of the present embodiment can easily generate rubber chipping even for a rubber composition having high rubber chipping resistance, and the accuracy close to the evaluation of tire chipping in the market. The rubber chipping resistance can be evaluated.

  The rubber chipping resistance evaluation method of the present embodiment, which is performed using the test apparatus 1 described above, includes a forming step for forming the rubber test piece 2, a test step for causing the striking piece 5 to collide with the rubber test piece 2, and And an evaluation step for evaluating the rubber chipping resistance performance from the rubber chipping state of the rubber test piece 2.

In the forming step, for example, a highly elastic member having a Young's modulus of 1.0 × 10 ⁸ Pa or more is used as the impact plate 13. Such an impact plate 13 is small in elastic deformation, receives an impact applied to the front surface Sa1 of the rubber test piece 2, and suppresses transmission to the rear surface Sa2 side. As the receiving plate 13 in a more preferable embodiment, for example, a metal plate having a Young's modulus of 1.0 × 10 ⁸ Pa or more is used. Such an impact plate 13 is easy to form and further suppresses the impact applied to the front surface Sa1 from being transmitted to the rear surface Sa2 side, and the impact is transmitted to the front surface Sa1 and the impact plate 13 of the rubber test piece 2. The rubber part in between acts more concentrated.

  In the formation process of the present embodiment, the rubber test piece 2 is formed by, for example, embedding the impact plate 13 in unvulcanized rubber and then vulcanizing. However, the rubber test piece 2 can also be formed, for example, by forming a cut in the vulcanized rubber and attaching the impact plate 13 in the cut.

  As shown in FIG. 3, in the forming step, the receiving plate 13 has an embedding depth D between its lower end and the upper surface Sb <b> 1 of the rubber test piece 2, for example, a height H of 1.4 described later. It is formed to be more than double. Thereby, the impact receiving plate 13 can further suppress the impact applied to the front surface Sa1 from being transmitted to the rear surface Sa2 side, and can suppress the separation from the rubber test piece 2 due to the impact. The upper end of the impact plate 13 may protrude from the upper surface Sb1 of the rubber test piece 2, but in a more preferred embodiment, the upper surface Sb1 is flush with the upper surface Sb1 in order to prevent contact between the impact plate 13 and the impact piece 5. Formed.

  As shown in FIG. 2, in the formation process of the present embodiment, the distance L between the impact plate 13 and the front surface Sa1 is formed in a range of 5 to 15 mm, for example. If the distance L is greater than 15 mm, the rubber test piece 2 formed from a rubber composition having high rubber chipping resistance may not be able to generate rubber chipping. On the contrary, when the distance L is less than 5 mm, the impact receiving plate 13 and the striking piece 5 may come into contact with each other.

  In the formation process of this embodiment, it is desirable that the receiving plate 13 is arranged in parallel with the front surface Sa1 of the rubber test piece 2. However, the impact receiving plate 13 may be inclined with respect to the front surface Sa1 of the rubber test piece 2.

  FIG. 5 (a) shows a plan view of the rubber test piece 2, and FIG. 5 (b) shows a side view of the rubber test piece 2. FIG. As shown in FIG. 5A, the impact plate 13 is disposed so as to be inclined within a range of 30 degrees or less with respect to the axial direction of the front surface Sa1 of the rubber test piece 2 in a plan view, for example. Also good. In this case, the distance L between the slanting receiving plate 13 and the front surface Sa1 of the rubber test piece 2 is the width in the axial direction of the rubber test piece 2 where the central portion in the axial direction of the impact piece main body 5A collides with the front surface Sa1. It is set as the distance L in the center part of W2.

  On the other hand, as shown in FIG. 5 (b), the impact plate 13 is disposed so as to be inclined within a range of 30 degrees or less with respect to the vertical direction of the front surface Sa1 of the rubber test piece 2 in a side view, for example. May be. In this case, the distance L between the inclined receiving plate 13 and the front surface Sa1 of the rubber test piece 2 is the height H in the vertical direction of the rubber test piece 2 where the lower corner portion Q of the striking piece main body 5A collides with the front surface Sa1. Let the distance be L. When the impact receiving plate 13 is inclined more than 30 degrees with respect to the front surface Sa1, the impact receiving plate 13 cannot receive the impact acting on the front surface Sa1, and this impact is detected by the front surface Sa1 and the impact receiving plate 13 of the rubber test piece 2. You may not be able to concentrate on the rubber part between.

  As shown in FIG. 2 or FIG. 4, it is desirable that the thickness t of the receiving plate 13 is formed to be 1.0 mm or more, for example. If the thickness t of the impact plate 13 is less than 1.0 mm, the impact plate 13 may not be able to receive the impact acting on the front surface Sa1. Further, the axial width W3 of the impact receiving plate 13 is desirably larger than, for example, the width W1 of the striking piece main body 5A. In the present embodiment, the width W3 is formed to be approximately the same as the width W2 of the rubber test piece 2. Yes. Even when the width W3 of the impact receiving plate 13 is smaller than the width W1 of the striking piece main body 5A, the impact receiving plate 13 may not be able to receive the impact acting on the front surface Sa1.

  As shown in FIG. 1, in the test process, first, the rubber test piece 2 is supported by the support 3, and the pendulum 4 is arranged at a position of the swing angle α at which the drop energy becomes a preset value. Next, the pendulum 4 is swung down, and the lower corner portion Q of the striking piece 5 is caused to collide with the upper portion of the front surface Sa1 of the rubber test piece 2 as indicated by a virtual line.

  As shown in FIG. 3, the collision position where the lower corner portion Q of the striking piece 5 collides with the front surface Sa1 is such that the height H from the upper surface Sb1 is in the range of 1.0 to 5.0 mm, for example. desirable. When the height H is less than 1.0 mm, the rubber test piece 2 is likely to have a rubber chip, and conversely, when the height H is greater than 5.0 mm, the rubber test piece 2 is less likely to have a rubber chip. In these cases, it may be difficult to accurately evaluate the rubber chipping resistance.

  In the test process of the present embodiment, the lower corner portion Q of the striking piece 5 collides with the upper portion of the front surface Sa1 of the test piece 2 when the arm 9 passes through the vertical line X or immediately before the vertical line passes. In the present embodiment, the rubber test piece 2 is supported by the support 3 so that the distance between the lower corner portion Q and the front surface Sa1 of the rubber test piece 2 when passing through the vertical line is 6.0 mm or less. Here, immediately before the passage of the vertical line means that the arm 9 passes the vertical line X when the striking piece 5 moves a distance of 6.0 mm forward from the passage of the vertical line, and when the vertical line passes. To the hitting piece 5 is moved to a front side by a distance of 6.0 mm.

  Further, in the test process of the present embodiment, it is desirable that the rubber test piece 2 is preheated in order to improve the reproducibility of rubber chipping during actual vehicle travel. The rubber test piece 2 of a more preferable embodiment is preheated so that the temperature at the time of collision is 40 to 150 ° C. in order to reproduce the temperature of the tire during running. As a result, in the test method of the present embodiment, for example, rubber alteration or the like that occurs during running of an actual vehicle due to heating also occurs in the rubber test piece 2, and the reproducibility of rubber chipping by the rubber test piece 2 is further enhanced. Further, the rubber chipping performance can be evaluated with higher accuracy.

  In the test process of this embodiment, the value of the drop energy of the pendulum 4 and the distance L of the impact plate 13 described above are each fixed to a preset reference value. And after a test process is complete | finished, the weight of the rubber | gum chip | piece which generate | occur | produced in the rubber test piece 2 is measured in an evaluation process. In the evaluation process of the present embodiment, the rubber chipping resistance performance of the rubber test piece 2 is evaluated based on the weight of the rubber chipping. According to such an evaluation method, rubber chipping can be easily generated even for a rubber composition having high rubber chipping resistance, and the rubber chipping performance with an accuracy close to the evaluation of tire chipping in the market. Can be evaluated in a short time.

  In the evaluation method of another embodiment, only the value of the drop energy of the pendulum 4 is fixed to the reference value in the test process. Then, a plurality of tests are performed while the distance L of the impact receiving plate 13 is greatly changed stepwise. Thereafter, in the evaluation step, the distance L of the impact receiving plate 13 where the rubber test piece is no longer chipped is determined, and the rubber chip resistance performance of the rubber test piece 2 is evaluated based on the determined distance L. The

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to these embodiment, It can deform | transform and implement in a various aspect.

(Test 1)
Various rubber test pieces for evaluation shown in Table 2 were produced from the rubber composition shown in Table 1. The rubber chipping resistance of these rubber test pieces was evaluated using the following evaluation method A according to the present invention, and compared with evaluation using a conventional evaluation method having no impact plate. The main common specifications are as follows.

Common specifications <Test equipment>
Arm length: 450mm
Swing up angle α: 90 °
Size of hitting piece main body: width W1 = 39 mm, height H1 = 29 mm, length L1 = 29 mm
Hitting piece weight: 3kg
Lower corner angle θ: 90 °
<Rubber specimen>
Size of rubber test piece: width W2 = 59 mm, height H2 = 24 mm, length L2 = 39 mm
Surface temperature: 80 ° C
Each test method is as follows.

<Evaluation method A>
The rubber generated in the rubber test piece was made by striking the hitting piece against each rubber test piece in which an impact plate (material: stainless steel, Young's modulus: 200 GPa, thickness: 1.0 mm) was embedded in the rubber composition of Table 1. The chip weight was measured. The evaluation is based on the reciprocal of the weight of the rubber chip, and is indicated by an index with Example 1 being 100. The larger the value, the better the rubber chip resistance.

<Conventional evaluation method>
According to the test method described in Patent Document 1, the rubber composition shown in Table 1 was used, and a plurality of cuts (length: 7.0 mm, width: 0.2 mm, depth: 7.0 mm, The striking piece was made to collide with a rubber test piece provided with a distance of 13.0 mm), and it was visually confirmed whether or not rubber chipping occurred in the rubber test piece. In the evaluation, the case where the rubber chip was confirmed was shown as “Yes”, and the case where the rubber chip was not confirmed was shown as “No”.

<Market evaluation>
A sample tire is mounted on all wheels of the test vehicle, and one driver rides on a general road including dry asphalt road surface, wet road surface, and rough terrain for 10,000 km. It was done. Evaluation is a rank in which each sample tire was compared based on the state of lack of rubber, and the smaller the numerical value, the better.

(Test 2)
Further, various rubber test pieces for evaluation shown in Table 3 were made from the rubber composition shown in Table 1. The rubber chipping resistance of these rubber test pieces was evaluated using the following evaluation method B according to the present invention.

<Evaluation method B>
Using the rubber composition shown in Table 1, rubber test pieces with different distances L between the receiving plate and the front surface are manufactured as trial pieces, and impact pieces are made to collide with each rubber test piece, resulting in rubber chipping in the rubber test pieces. It was observed visually. As the receiving plate, a material: stainless steel, Young's modulus: 200 GPa, thickness: 1.0 mm was used. In the evaluation, the case where rubber chipping was confirmed was shown as “Yes”, the case where rubber chipping was not confirmed was shown as “no”, and the rubber chipping resistance was better as the rubber chipping was not confirmed.

  From the test results, in the evaluation method of the present invention, the same result as the market evaluation can be obtained by measuring the weight of the rubber chip generated in the rubber test piece or observing the presence or absence of the rubber chip of the rubber test piece. I was able to confirm. Furthermore, in the evaluation method of the present invention, it was confirmed that rubber chipping could occur even in a rubber test piece having high rubber chipping resistance that does not cause rubber chipping in the conventional evaluation method. In the evaluation method B of the present invention, it was also confirmed that the same results as the market evaluation can be obtained by subdividing the distance L between the receiving plate and the front face and setting a plurality of distances.

DESCRIPTION OF SYMBOLS 1 Test apparatus 2 Rubber test piece 3 Support tool 4 Pendulum 5 Strike piece 9 Arm 13 Receiving plate Q Lower corner part Sa1 Front surface X Vertical line i Axis center

Claims (7)

The striking piece of the pendulum provided with a striking piece on the other end of the arm pivoted at one end at a horizontal axis is made to collide with the front surface of the rubber test piece supported by the support, and the pendulum fall energy and The rubber chipping resistance evaluation method for evaluating the rubber chipping resistance performance from the state of the rubber chipping of the rubber test piece,
The rubber test piece has a rectangular block shape surrounded by front and rear surfaces, upper and lower surfaces, and both side surfaces, and the front surface is supported in parallel with the axial direction,
The striking piece of the pendulum has a lower corner portion where a facing surface facing the front surface and a lower surface facing downward intersect at the time of collision, and the arm passes a vertical line passing through a vertical line extending from the axis or a vertical Immediately before passing through the line, the lower corner portion collides with the front surface,
The rubber test piece is characterized in that a hard impact plate is embedded in the rubber test piece and at a distance L from the front side to the rear side. The rubber chipping resistance evaluation method according to claim 1, wherein the impact plate has a Young's modulus of 1.0 × 10 ⁸ Pa or more.   3. The rubber chipping resistance evaluation method according to claim 2, wherein the impact plate is a metal plate.   4. The rubber-resistant chipping according to claim 1, wherein the lower corner portion collides with the front surface at a height H from the upper surface of 1.0 to 5.0 mm. Performance evaluation method.   5. The rubber chipping resistance evaluation method according to claim 4, wherein an embedding depth D of the lower end of the impact plate from the upper surface is 1.4 times or more of the height H.   The rubber chipping resistance is evaluated by fixing the value of the pendulum drop energy and the distance L of the impact plate to a reference value, and using the size of the rubber chipping weight of the rubber test piece as an index. The rubber chipping resistance evaluation method according to any one of claims 1 to 5.   The rubber chipping resistance is characterized in that the value of the pendulum drop energy is fixed at a reference value, and the rubber chipping resistance is evaluated by using the distance L of the impact plate at which no rubber chipping occurs in the rubber test piece as an index. The rubber chipping resistance evaluation method according to any one of claims 1 to 5.

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