JP2018146485A - Method for evaluating abrasion of rubbers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating abrasion of rubbers.SOLUTION: According to a method for evaluating abrasion of rubbers, a first rubber plate and a second rubber plate are brought into contact with each other, the second rubber plate is pressed against the first rubber plate, one of the first rubber plate and the second rubber plate is fixed, the other rubber plate is vibrated in a direction vertical to a direction of pressing, and the first and second rubbers are abraded against each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for evaluating wear between rubbers.

  Conventionally, as a method for evaluating wear of rubber, for example, a JIS standard wear test method such as JIS K6264-2: 2005 is known. According to the JIS standards as described above, rubber wear is evaluated by wearing rubber with a material different from rubber.

  On the other hand, in a railway vehicle, a product called protective rubber is used at a connecting portion between the front and rear vehicles for the purpose of preventing a person from falling from the platform to the space portion of the connecting portion. A rubber plate is usually used as the protective rubber.

The protective rubber will be described below with reference to the accompanying drawings.
FIG. 4 is a diagram schematically illustrating a state in which the protective rubber is attached to the vehicle. FIG. 5 is a part of a BB cross-sectional view of FIG.
In FIG. 4, protective rubber 12 is attached to each of the front and rear vehicles 1.
In FIG. 5, the end surfaces 14 of the protective rubber 12 are flat. The end surface of the protective rubber (for example, the surface where the two protective rubbers face each other) may be rounded.

As described above, the two protective rubbers between the vehicles face each other. For this reason, there are cases where the edges of the protective rubber come into contact with each other during the operation of the train (for example, on a curved line or in an uneven garage). If a rubber material with poor wear resistance is used for the protective rubber, the protective rubber may cause uneven wear when the protective rubbers are in contact with each other.
For this reason, it is necessary to evaluate the abrasion of rubber by abrading rubbers.
However, as described above, conventionally, wear of rubber has been evaluated by wearing rubber with a material different from rubber.
For this reason, the conventional method for evaluating the wear of rubber cannot sufficiently reproduce the situation of wear of the protective rubber actually used.

  Then, an object of this invention is to provide the evaluation method of abrasion between rubber | gum.

As a result of intensive studies to solve the above problems, the present inventors use a wear evaluation apparatus in which two pedestals capable of fixing a plate-like rubber are installed in a biaxial testing machine that can be displaced in a vertical direction and a horizontal direction, respectively. As a result, it was found that the abrasion between rubbers can be evaluated, and the present invention has been achieved.
The present invention is based on the above knowledge and the like, and specifically, solves the above problems by the following configuration.

1. Bringing the first rubber plate and the second rubber plate into contact with each other;
Pressing the second rubber plate against the first rubber plate;
Fixing the first rubber plate or the second rubber plate;
The other rubber plate is vibrated in the vertical direction with respect to the pressing,
A method for evaluating wear between rubbers, wherein the first rubber and the second rubber are worn (the evaluation method of the present invention).
2. 2. The evaluation method according to 1 above, wherein the end surface of the first rubber plate and the end surface of the second rubber plate are brought into contact with each other.

3. Placing a second rubber plate on the first rubber plate and bringing the first rubber plate and the second rubber plate into contact with each other;
After the step 1, the second rubber plate is pressed against the first rubber plate in the vertical direction, and the second rubber plate is fixed.
After the step 2, with the second rubber plate fixed, the first rubber is vibrated in the horizontal direction, and the first rubber and the second rubber are rubbed together to wear. A method for evaluating wear between rubbers.
In addition, said 3 is one of the suitable aspects of the evaluation method of this invention.

4). In the step 2, the overall height 1 of the first rubber plate and the second rubber plate after the pressing is equal to the total height of the first rubber plate and the second rubber plate before the pressing. 4. The evaluation method according to 3 above, which is 5 to 20 mm smaller than the height 2.
5. 5. The evaluation method according to 3 or 4 above, wherein in the step 3, the amplitude of the vibration is within ± 50 mm, and the amplitude period of the vibration is 0.1 to 0.5 Hz.
6). In the step 1, the first rubber plate and the second rubber plate are set up vertically,
Disposing the second rubber plate on the first rubber plate;
The evaluation method according to any one of 3 to 5, wherein the upper end surface of the first rubber plate and the lower end surface of the second rubber plate are crossed and brought into contact with each other.
7). 7. The evaluation method according to 6 above, wherein an angle between the center line of the first rubber plate and the center line of the second rubber plate is 15 to 45 °.

  According to the present invention, wear between rubbers can be evaluated.

1 is a schematic perspective view of a wear evaluation apparatus used for wear test I in the present invention. 1 is a schematic right side view of a wear evaluation apparatus used for wear test I in the present invention. In a wear evaluation apparatus, it is a typical figure showing the contact angle of an upper and lower rubber board. It is a figure showing typically the state where protection rubber was attached to vehicles. It is a part of BB sectional drawing of FIG.

[Method for evaluating wear between rubbers]
As a specific aspect of the method for evaluating wear between rubbers of the present invention (the evaluation method of the present invention), the wear test I will be described below.
In the present invention, a wear test I used for evaluating wear between rubbers will be described below with reference to the accompanying drawings. The present invention is not limited to the attached drawings.
FIG. 1 is a schematic perspective view of a wear evaluation apparatus used in the wear test I in the present invention.
FIG. 2 is a schematic right side view of the wear evaluation apparatus used in the wear test I in the present invention. 2 is a side view of the wear evaluation apparatus shown in FIG. Moreover, in FIGS. 1-3, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

In FIG. 1, the wear evaluation apparatus 801 includes rubber plates 810 and 812 and fixing portions 814 and 816.
The fixing portion 816 includes two fixing plates 826 and two fasteners 828. The fixing portion 816 sandwiches the rubber plate 812 with the two fixing plates 826 and fixes the rubber plate 812 between the two fixing plates 826 with the two fasteners 828. In the present invention, the fixing part is not particularly limited as long as it can fix the rubber plate. The same applies to the fixing portion 814.
The fixed portion 816 is movable in the vertical direction. The fixed portion 814 is movable in the horizontal direction. Note that a driving device for driving the fixing portion 816 in the vertical direction is omitted. The same applies to the fixing portion 814.

As an operation procedure of the abrasion test I, first, the rubber plate 810 was fixed to the fixing portion 814, and the rubber plate 812 was fixed to the fixing portion 816.
Next, with the fixing portion 814 stationary, the fixing portion 816 is lowered in the vertical direction (arrow 818) to bring the end surface 822 of the rubber plate 810 into contact with the end surface 824 of the rubber plate 812 (corresponding to step 1). .

At the time of the contact, the rubber plate 810 and the rubber plate 812 were crossed and brought into contact with each other.
FIG. 3 is a schematic diagram showing the contact angles of the upper and lower rubber plates in the wear evaluation apparatus. FIG. 3 is a view of only the upper and lower rubber plates in the wear evaluation apparatus observed from above the wear evaluation apparatus.
When the rubber plate 810 and the rubber plate 812 are brought into contact with each other, as shown in FIG. 3, the angle (contact) between the center line (in the lateral direction) of the rubber plate 810 and the center line (in the lateral direction) of the rubber plate 812 The rubber plate 810 and the rubber plate 812 were crossed so that the angle θ) was 30 °.
In the present invention, the first rubber plate and the second rubber plate are arranged so as to intersect with each other in the vertical direction, are brought into contact with each other, and the center line (in the lateral direction) of the first rubber plate is observed from above. And the angle between the center line (in the lateral direction) of the second rubber plate can be changed in the range of 15 to 45 °.

Next, from the state where the rubber plate 810 and the rubber plate 812 were in contact as described above, the fixing portion 816 was further lowered by 10 mm in the direction of the arrow 818, and the rubber plate 810 and the rubber plate 812 were pressed. After the fixing part 816 was lowered by 10 mm, the fixing part 816 and the rubber plate 812 were fixed (corresponding to step 2). Note that the rubber plate 810 and / or the rubber plate 812 may be bent after the fixing portion 816 is lowered by 10 mm.
In step 2, the overall height 1 of the first rubber plate and the second rubber plate after being pressed (pressurized) can be appropriately changed depending on the sizes of the first rubber plate and the second rubber plate.
The total height of the first rubber plate and the second rubber plate used (the total height 2 of the first rubber plate and the second rubber plate before pressing (pressing)) is used, For example, when the height is 20 to 100 cm, the height 1 can be 5 to 20 mm smaller than the height 2.

Next, in a state where the fixing portion 816 and the rubber plate 812 are fixed at the above positions, the fixing portion 814 and the rubber plate 810 are horizontally (in the direction of the double arrow 820) with an amplitude of ± 30 mm, an amplitude period of 0.1 Hz, and an amplitude. A wear test was performed in which the rubber plates 810 and 812 were rubbed with each other with the amplitude (reciprocating) under the condition of 8,000 times (corresponding to step 3).
In the present invention, the number of vibration amplitudes can be changed in the range of 1,000 to 8,000 times.
In the present invention, the amplitude of vibration can be changed within a range of ± 50 mm. The amplitude can be ± 10 mm or more.
In the present invention, the amplitude period of the vibration can be changed within a range of 0.1 to 0.5 Hz.

After completion of the wear test I, the rubber plates 810 and 812 were removed from the wear evaluation apparatus 801, and the weights of the rubber plates 810 and 812 after the wear test I were measured.
The total weight of the rubber plates 810 and 812 after the wear test I was subtracted from the total weight of the rubber plates 810 and 812 before the wear test I, and the obtained value was defined as the wear amount.
The amount of wear (unit: g) is shown in the column of wear test I in Table 1.
In the present invention, the wear amount may be evaluated by a change in volume of the two rubber plates.

<< Rubber board >>
The rubber plate used in the evaluation method of the present invention will be described below.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In this specification, unless otherwise specified, each component can be used alone or in combination of two or more of the substances corresponding to the component. When a component contains two or more types of substances, the content of the component means the total content of the two or more types of substances.

The rubber plate used in the present invention is not particularly limited.
The rubber plate may be a rubber plate.
Examples of the size of the rubber plate include a length of 15 to 25 cm, a width of 25 to 40 cm, and a thickness of 1.5 to 2.5 cm.
Further, the end surface of the rubber plate may be either a flat surface or a curved surface.

  The rubber plate is preferably formed of a rubber composition (composition). As said composition, the composition containing an ethylene-propylene-diene terpolymer and sulfur is mentioned as one of the preferable aspects, for example.

<Ethylene-propylene-diene terpolymer>
The composition contains an ethylene-propylene-diene terpolymer (EPDM).
The ethylene-propylene-diene terpolymer is a copolymer of ethylene, propylene and diene.
Examples of the diene include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, and cyclooctadiene. Of these, dicyclopentadiene is preferred from the viewpoint of excellent rolling processability.

  In the present specification, the solubility parameter (solubility parameter, SP value) is a value obtained by calculation according to its chemical structural formula according to the Small formula described in Encyclopedia of Polymer science and Technology 3.

  The iodine value of EPDM is more preferably from 3 to 25, and even more preferably from 3 to 20, from the viewpoint of chemical resistance and weather resistance. The iodine value is measured according to JIS K6235: 2006.

The Mooney viscosity of EPDM is preferably 30 to 80 and more preferably 50 to 70 from the viewpoint of excellent rolling processability. The Mooney viscosity (ML _{1 + 4} ) is based on JIS K6300-1: 2013, using an L-type rotor with Mooney viscometer, preheating time 1 minute, rotor rotation time 4 minutes, temperature 100 ° C., 2 rpm It was measured under the conditions of

  The amount of diene in EPDM (ratio occupied by repeating units derived from diene in EPDM) is preferably 1 to 15% by mass and more preferably 5 to 11% by mass because of excellent vulcanization properties. preferable. The amount of diene in EPDM is evaluated according to ASTM D 6047.

The weight average molecular weight (Mw) of EPDM is preferably 1.0 × 10 ^{5 to} 2.0 × 10 ⁶ , and preferably 1.5 × 10 ⁵ to 1.5 × 10 ⁵ , because of the excellent balance between rolling processability and vulcanized physical properties. More preferably, it is 5.0 × 10 ⁵ . The weight average molecular weight of EPDM is a standard polystyrene conversion value measured by gel permeation chromatography (GPC) using orthodichlorobenzene as a solvent.

  The production method of EPDM is not particularly limited. For example, a conventionally well-known thing is mentioned.

<Sulfur>
It is mentioned as one of the aspects with preferable that the said composition contains sulfur.
When the above composition contains sulfur, the hardness of the resulting vulcanized rubber can be adjusted to an appropriate range for the use of the outer hood.

The sulfur is not particularly limited as long as it can be used for vulcanization of the rubber composition. For example, a conventionally well-known thing is mentioned.
It does not restrict | limit in particular about the manufacturing method of sulfur.

(Sulfur content)
The content of sulfur is 0.5 to 3.0 parts by mass with respect to 100 parts by mass of EPDM, from the viewpoints of excellent wear resistance and rolling workability, high hardness of vulcanized rubber, and excellent vulcanized physical properties. Is preferable, and 1.0-2.0 mass parts is more preferable.

<Tackifier>
The composition preferably further contains a tackifier, and from the viewpoint of excellent rolling processability and wear resistance, it contains a tackifier having a solubility parameter (solubility parameter, SP value) of 9.5 or more. More preferably.

  The SP value of the tackifier is preferably 10.7 to 12.5, and more preferably 11.0 to 12.0, from the viewpoint that the effect of the present invention is excellent and the wear resistance is excellent.

Examples of the tackifier include alkylphenol resins, resorcin resins, and cresol resins.
Of these, alkylphenol resins are preferred from the viewpoints of excellent effects of the present invention and excellent vulcanization properties.
The number of carbon atoms of the alkyl group contained in the alkylphenols that can constitute the alkylphenol resin is preferably 6 to 12 from the viewpoint of being excellent due to the effects of the present invention and excellent vulcanization properties. The alkyl group can be either linear or branched.

  The method for producing the tackifier is not particularly limited. For example, a conventionally well-known thing is mentioned.

(Content of tackifier)
The content of the tackifier is 2 to 20 parts by mass with respect to 100 parts by mass of the ethylene-propylene-diene terpolymer from the viewpoint of excellent balance of rolling workability, wear resistance and vulcanized physical properties. Is preferable, and 5 to 15 parts by mass is more preferable.

(White filler or carbon black)
From the viewpoint that the composition has excellent reinforcing properties and the color of the rubber can be changed, the composition further includes at least one selected from the group consisting of a white filler and carbon black as one of preferred embodiments. It is done.
When the said composition contains a white filler further, the color of the rubber | gum obtained can be made into white.
When the said composition contains a white filler and carbon black further, the color of the rubber | gum obtained can be made into gray or black by adjusting content of carbon black with respect to a white filler.
Content of a white filler can be 100 mass parts or less with respect to 100 mass parts of ethylene-propylene-diene terpolymers. The same applies to the carbon black content.

(White filler)
Examples of the white filler include titanium oxide and / or silica.
The composition preferably further contains titanium oxide and silica from the viewpoint of excellent rolling processability, wear resistance, and vulcanized physical properties.

(Titanium oxide)
Titanium oxide is not particularly limited. For example, a conventionally well-known thing is mentioned.

(silica)
Silica is not particularly limited. For example, a conventionally well-known thing is mentioned.

(Total amount of titanium oxide and silica)
When the composition further contains titanium oxide and silica, the total amount of titanium oxide and silica is an ethylene-propylene-diene ternary copolymer from the viewpoint of excellent balance of rolling processability, wear resistance, and vulcanized physical properties. 100 mass parts or less are preferable with respect to 100 mass parts of polymers, and 50-85 mass parts is more preferable.

(Carbon black)
Carbon black is not particularly limited. For example, a conventionally well-known thing is mentioned.

(Total amount of white filler and carbon black)
In the case where the composition further contains a white filler (for example, titanium oxide and silica) and carbon black, the total amount of the white filler (for example, titanium oxide and silica) and carbon black depends on the rolling processability, resistance to resistance. From the viewpoint of excellent wear and vulcanized physical properties, 100 parts by mass or less is preferable with respect to 100 parts by mass of the ethylene-propylene-diene terpolymer, and 55 to 85 parts by mass is more preferable.

(Other ingredients)
The composition may further contain an additive. Examples of the additives include polymers other than EPDM, silane coupling agents, anti-aging agents, antioxidants, pigments, dyes, softeners such as paraffin oil, plasticizers, zinc oxide, stearic acid, thixotropic agents. Giving agent, UV absorber, solvent, surfactant (including leveling agent), dispersant, dehydrating agent, rust preventive agent, antistatic agent, thixotropy imparting agent, vulcanization aid, vulcanization accelerator, vulcanization Examples include retarders, alcohols such as diethylene glycol, and the like.

(Method for producing the above composition)
The method for producing the composition is not particularly limited. For example, a method of uniformly mixing the above-described components with a roll, a kneader, an extruder, a universal agitator or the like can be mentioned.

(Sulfur vulcanization)
When the composition contains sulfur, such a composition can be sulfur vulcanized to obtain a vulcanized rubber.
The method of sulfur vulcanization is not particularly limited, and examples thereof include a method of heating the composition (for example, about 160 ° C.). You may pressurize with the said heating.

(Use)
The composition (or (vulcanized) rubber formed using the composition) is suitably used for an outer hood (for example, protective rubber) of a railway vehicle, for example.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
<Production of composition>
The components shown in Table 1 below (excluding sulfur and vulcanization accelerator) were added to the kneader mixer at the ratio (parts by mass) shown in the same table and mixed for about 10 minutes to obtain a mixture.
Next, the mixture obtained as described above is wound around a kneading roll, and sulfur and a vulcanization accelerator shown in Table 1 below are added thereto in a ratio (part by mass) shown in the same table, and about 5 Each composition was kneaded for 1 minute.

<Manufacture of rubber plate>
Each composition (formulations A and B) produced as described above was press-vulcanized at 160 ° C. for 60 minutes, and two rubber plates having a length of 20 cm, a width of 30 cm, and a thickness of 2 cm were prepared for each composition. In each of the rubber plates, one of the sides having a length of 30 cm (the side) is a semicircle having a diameter of 2 cm.
The weight of the two rubber plates obtained as described above was measured.

<Evaluation>
Using the rubber plate produced as described above, the wear test I and the following wear test II were performed. The results are shown in Table 1.

<Abrasion test II (comparative example)>
JIS K6264-2: 2005 11. According to the Taber abrasion test, a rubber abrasion test was performed in which the rubber was abraded with an abrasive wheel.
In the abrasion test II, a sample cut out to a size according to the above JIS from each rubber plate produced as described above was used as a test piece. The thickness of the test piece was 12.7 mm.
Abrasion test II was performed under the conditions of test temperature [room temperature], load [9.8 N], rotational speed of rotating disk [60 rpm], test rotational speed [1,000 times], and polishing seed [H18].

Details of each component shown in Table 1 are as follows.
EPDM: ESPRENE305 (manufactured by Sumitomo Chemical Co., Ltd., ethylene-propylene-dicyclopentadiene terpolymer, Mooney viscosity: 60, ethylene content: 60 mass%, diene content: 7.5 mass%, SP value of 8.0, Iodination 20, weight average molecular weight 3.0 × 10 ⁵ )

・ Silica: Nip seal VN3 (made by Nippon Silica)
-Paraffin oil: Machine oil (made by Showa Shell Sekiyu KK)
・ Titanium oxide: R-650 (manufactured by Sakai Chemical Industry Co., Ltd.)

Alkylphenol resin: tackifier, hitanol 1502Z (manufactured by Hitachi Chemical, p-octylphenol resin, SP value 11.3

Silane coupling agent: BIS- (3- (Triethoxysilyl) propyl) tetrasulfide, trade name KBE-846, manufactured by Shin-Etsu Chemical Co., Ltd.

・ Zinc oxide: Ginbae R (Toho Zinc Co., Ltd.)
・ Stearic acid: LUNAC YA (manufactured by Kao Corporation)
・ Diethylene glycol: manufactured by Nippon Shokubai Co., Ltd.

・ Vulcanization accelerator BZ: Noxeller BZ-P (Ouchi Shinsei Chemical Co., Ltd., dithiocarbamate)
・ Vulcanization accelerator TS: Sunseller TS-G (manufactured by Sanshin Chemical Industry Co., Ltd., Chiuram)
・ Vulcanization accelerator M: Sunseller M-PO (manufactured by Sanshin Chemical Industry Co., Ltd., thiazole)

・ Sulfur: Oil-treated sulfur (5% oil-treated) (Hosoi Chemical Industries)

  As is clear from the results shown in Table 1, in the abrasion test II where the rubber is worn with a material different from the rubber, the amount of wear of the rubber plate of the blend B is larger than that of the blend A.

On the other hand, in the evaluation method of the present invention, the wear amount of the rubber plate of compounding B was less than that of compounding A.
Thus, according to the evaluation method of the present invention, wear between rubbers can be accurately reproduced.

DESCRIPTION OF SYMBOLS 1 Vehicle 12 Protective rubber 14 End surface 801 Wear evaluation apparatus 810, 812 Rubber plate 814, 816 Fixed part 818, 830 Arrow 820 Double arrow 822, 824 End surface 826 Fixed plate 828 Fastener

Claims (7)

Bringing the first rubber plate and the second rubber plate into contact with each other;
Pressing the second rubber plate against the first rubber plate;
Fixing the first rubber plate or the second rubber plate;
The other rubber plate is vibrated in the vertical direction with respect to the pressing,
A method for evaluating wear between rubbers, wherein the first rubber and the second rubber are worn.   The evaluation method according to claim 1, wherein an end face of the first rubber plate and an end face of the second rubber plate are brought into contact with each other. Placing a second rubber plate on the first rubber plate and bringing the first rubber plate and the second rubber plate into contact with each other;
Step 2 after pressing the first rubber plate against the first rubber plate in the vertical direction to fix the second rubber plate after the step 1;
After the step 2, with the second rubber plate fixed, the first rubber is vibrated in the horizontal direction, and the first rubber and the second rubber are rubbed together to wear. A method for evaluating wear between rubbers.   In the step 2, the overall height 1 of the first rubber plate and the second rubber plate after the pressing is equal to the total height of the first rubber plate and the second rubber plate before the pressing. The evaluation method according to claim 3, wherein the evaluation method is 5 to 20 mm smaller than the height 2.   5. The evaluation method according to claim 3, wherein, in the step 3, an amplitude of the vibration is within ± 50 mm, and an amplitude period of the vibration is 0.1 to 0.5 Hz. In the step 1, the first rubber plate and the second rubber plate are vertically set up,
Disposing the second rubber plate on the first rubber plate;
The evaluation method according to any one of claims 3 to 5, wherein an upper end surface of the first rubber plate and a lower end surface of the second rubber plate are crossed and brought into contact with each other. The evaluation method according to claim 6, wherein an angle between a center line of the first rubber plate and a center line of the second rubber plate is 15 to 45 °.