JP4839348B2 - Anti-vibration rubber and motor fixing mount - Google Patents

Abstract

The invention provides a vibration-damping rubber and a motor-fixing mount, which exhibit good processability, and exhibit improved heat dissipation properties (thermal conductivity) while maintaining a low compression permanent deformation even at high temperatures, by blending specific amounts of acetylene black and graphite into NBR rubber. A vibration-damping rubber is characterized by comprising a NBR composition containing 10 to 120 parts by weight of graphite, 10 to 80 parts by weight of acetylene black and 100 parts by weight of NBR rubber. The NBR composition preferably has a hardness of 75 or less as measured according to JIS K6253 (using a durometer A), having a compression permanent deformation of 36% or less as measured after an aging and heat resistance test at 100 DEG C for 70 hours according to JIS R6262 (using a large test piece), having a tan delta (10 Hz) of 0.3 or more, and also having heat dissipation properties such that the measured value of a thermal conductivity test is 60 DEG C or more. And a motor-fixing mount preferably is composed of the vibration-damping rubber interposed between plates.

Description

  The present invention relates to an anti-vibration rubber and a motor fixing mount, and more particularly, an anti-vibration rubber having good processability and capable of improving heat dissipation (thermal conductivity) while maintaining compression set even at high temperatures. It relates to a motor fixing mount.

  In order to suppress vibration and noise caused by a motor such as an OA device, a motor fixing mount in which a vibration-proof rubber is generally sandwiched between a motor and a support member that supports the motor is used.

  Conventionally, it has been proposed to use a material having good thermal conductivity for the purpose of releasing heat generated when the motor is driven in the vibration-proof rubber (Patent Documents 1 and 2).

  In Patent Documents 1 and 2, silicone rubber or other synthetic rubber is used as the rubber material.

  However, silicon rubber is weak in strength and has a problem in that it stably supports the motor for a long period of time. Also, in other synthetic rubbers, outgassing may be a problem for polymers containing chlorine or the like.

Therefore, it is conceivable to use NBR rubber that is inexpensive and relatively excellent in strength stability as a rubber material that does not have the above problems.
JP-A-6-143485 JP-A-5-168193

  However, in order to improve the thermal conductivity, when a commonly known thermal conductive filler such as graphite or acetylene black is blended with NBR, the compression set of the rubber composition deteriorates due to high use conditions. There has been a problem that rubber is easily flattened.

  For example, when graphite or acetylene black is blended alone as a thermally conductive filler, for example, if only acetylene black is blended, processability is poor (Comparative Example 1), and if only graphite is blended, heat dissipation is poor (Comparative Example). 2, Comparative Example 3).

  Further, when graphite and acetylene black are used in combination, for example, if graphite is added in the range of 10 to 120 parts by weight and acetylene black is less than 10 parts by weight, sufficient heat dissipation cannot be obtained (Comparative Example 7). Further, when acetylene black is added in an amount of more than 80 parts by weight, the hardness of the molded product becomes too high or the moldability deteriorates. Furthermore, when acetylene black is blended in the range of 10 to 80 parts by weight and the graphite is less than 10 parts by weight, sufficient heat dissipation cannot be obtained (Comparative Example 8), and when graphite is blended more than 120 parts by weight. After all, the hardness of the molded product becomes too high and the compression set is deteriorated.

  In addition, in order to mass-produce the anti-vibration rubber and the motor fixing mount of the present invention, good workability is required.

  Therefore, the problem of the present invention is that even if a specific amount of acetylene black and graphite is blended with NBR rubber, the workability is good and the heat dissipation (thermal conductivity) is maintained while the compression set is kept low even at high temperatures. An object of the present invention is to provide an anti-vibration rubber and a motor fixing mount capable of improving the vibration resistance.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
For fixing a motor, characterized in that the anti-vibration rubber comprising an NBR composition containing 10 to 120 parts by weight of graphite and 10 to 80 parts by weight of acetylene black is sandwiched between plates per 100 parts by weight of NBR rubber. mount.

  According to the present invention, even if graphite and acetylene black, which are heat conductive fillers, are blended with NBR rubber by a specific blending method, workability (roll processability, kneadability) is good and compression is performed even at high temperatures. An anti-vibration rubber and a motor fixing mount that can improve heat dissipation (thermal conductivity) in a state where the permanent set is kept low can be provided.

  Furthermore, the present invention can improve heat dissipation (thermal conductivity) and simultaneously improve material strength and vibration isolation performance while maintaining a low compression set.

  Embodiments of the present invention will be described below.

  The NBR composition used in the present invention is characterized by containing 10 to 120 parts by weight of graphite and 10 to 80 parts by weight of acetylene black as a heat conductive filler with respect to 100 parts by weight of NBR rubber.

  For NBR rubber, the minimum Mooney viscosity measured by Mooney scorch test (at 125 ° C., residual heat 1 minute, L-shaped rotor) in accordance with JIS K6300 is 60 M or less in terms of moldability and roll processability. preferable.

  The NBR rubber used in the present invention can be obtained as a commercial product, and examples of the commercial product include Nipol DN3350 manufactured by Nippon Zeon Co., Ltd.

  As the graphite, those having an average particle diameter of 20 μm or less are preferable. Here, the average particle diameter is measured by a centrifugal sedimentation method. An average particle size of 20 μm or less is preferable from the viewpoint of high filling into rubber. A more preferable average particle diameter of graphite is in the range of 5 to 15 μm.

  In the present invention, two or more types having different average particle diameters may be blended.

  The graphite of the present invention is available as a commercial product, and examples of the commercial product include “Graphite A-0”, “Graphite G-6S”, and “Graphite CPS-3S” manufactured by Chuetsu Graphite Industries.

  As a compounding quantity of graphite, it is the range of 10-120 weight part with respect to 100 weight part of NBR rubber, Preferably it is the range of 30-100 weight part, More preferably, it is the range of 50-80 weight part. When the blending amount is less than 10 parts by weight, sufficient heat dissipation cannot be obtained. When the blending amount is more than 120 parts by weight, there is a problem that the hardness of the molded article becomes too high and the compression set is deteriorated.

  Next, as acetylene black, those having an average particle size of 50 nm or less are preferably used. The average particle diameter is measured by a dynamic scattering method. An average particle size of 50 nm or less is preferable from the viewpoint of high filling into rubber.

  The acetylene black of the present invention can be obtained as a commercial product, and examples of the commercial product include “DENKA BLACK” manufactured by Denki Kagaku Kogyo Co., Ltd. As a compounding quantity, it is the range of 10-80 weight part with respect to 100 weight part of NBR rubber, Preferably it is the range of 20-50 weight part, More preferably, it is the range of 30-40 weight part. When the blending amount is less than 10 parts by weight, the heat dissipation is poor. When the blending amount is more than 80 parts by weight, the hardness becomes too high, which causes a problem in roll processability such as roll floating during production, and also a problem in rubber kneading. .

  In the present invention, the use of acetylene black among carbon blacks is particularly advantageous in that high heat dissipation can be obtained and compression set can be improved.

  In the composition of the present invention, various reinforcing agents, anti-aging agents, fillers, vulcanizing agents, vulcanization accelerators and the like can be appropriately blended as long as the effects of the present invention are not impaired.

  Examples of vulcanizing agents include sulfur, organic sulfur-containing compounds, organic vulcanizing agents such as oximes (for example, quinonedioxime compounds), organic peroxides, metal oxides, organic polyvalent amine compounds, and modified phenolic resins. Can be mentioned.

  These vulcanizing agents are preferably in the range of about 0.2 to 10 parts by weight, more preferably about 0.5 to 8 parts by weight, per 100 parts by weight of rubber.

  Examples of sulfur include powdered sulfur, precipitated sulfur, and colloidal sulfur.

  Examples of organic sulfur-containing compounds include tetramethylthiuram, disulfide, selenium dimethyldithiocarbamate, and the like.

  Examples of the organic peroxide include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, benzoyl peroxide, cumyl peroxide, 1 , 3-di (tert-butylperoxy) isopropylbenzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, m-toluoyl peroxide, dipropionyl peroxide and the like.

  Examples of the metal oxide include zinc white and magnesium oxide.

  In the present invention, various additives such as stabilizers, tackifiers, mold release agents, pigments, flame retardants, lubricants and the like can be added. In addition, a small amount of thermoplastic resin or rubber can be added to improve wear and moldability. Furthermore, short fibers and the like can be added within a range that does not impair the effects of the present invention in order to improve strength and rigidity.

  The NBR composition used in the present invention is prepared by, for example, using the above-mentioned compound with a heating kneader, for example, a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, a Brabender, a kneader, a high shear mixer, or the like. Then, it can be produced by melting and kneading, adding a vulcanizing agent, a vulcanizing auxiliary, etc., mixing these necessary components at the same time, and heating and kneading.

  Molding (vulcanization) is performed by heating at about 150 to 200 ° C. for about 3 to 60 minutes using a known method, for example, an injection molding machine, a compression molding machine, a vulcanizing press, and the like. Secondary crosslinking is also performed by heating at about 150 to 250 ° C. for about 1 to 24 hours.

  An example of the vibration isolating rubber of the present invention and a motor fixing mount using the same will be described with reference to the drawings.

  FIG. 1 is a sectional view showing a state in which a motor fixing mount according to the present invention is fixed to a motor and a bracket, and FIG. 2 is a sectional view showing a motor fixing mount 2 in FIG.

  As shown in FIG. 1, the motor 1 is supported by a bracket 3 that is a support member via a motor fixing mount 2.

  4 is an anti-vibration rubber, which is composed of the NBR composition. The anti-vibration rubber 4 can use the above-mentioned NBR composition as it is, or may contain other components, but is preferably used as it is. The layer configuration may be a single layer or a plurality of layers.

  Reference numeral 5 denotes a plate, 5a denotes a screw hole, 6 denotes an operating shaft, and 7 denotes an insertion hole.

  In addition, the NBR composition used in the present invention has a hardness (durometer A) of 75 or less according to JIS K6253, and when used as a vibration-proof rubber or a motor fixing mount, it is easy to create a thin one. Become.

  Furthermore, the NBR composition used in the present invention has a compression set (after a large test piece) after heat aging at 100 ° C. for 70 hours in accordance with JIS K6262 of 36% or less, and the rubber composition is difficult to sag. Become.

  Furthermore, since the tan δ (10 Hz) is 0.3 or more, the NBR composition used in the present invention is excellent in vibration-proof performance. Furthermore, since the measured value by a thermal conductivity test will be 60 degreeC or more, it is excellent also in heat dissipation.

  The NBR composition capable of obtaining such characteristics contains 10 to 120 parts by weight of graphite and 10 to 80 parts by weight of acetylene black as a heat conductive filler with respect to 100 parts by weight of the NBR rubber, thereby allowing heat conduction. Even if a filler is blended, processability (roll processability, kneadability) is good, and heat dissipation is improved while maintaining compression set without damaging rubber when used at high temperatures Furthermore, the material strength and the vibration isolating performance can be improved at the same time.

  Further, the motor fixing mount of the present invention can have good heat dissipation while stably supporting the motor for a long time even when used in a place where heat is applied.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited by this Example.

Example 1
<Blend ingredients and blending amounts>
Polymer: NBR rubber
(Nipol DN3350 manufactured by Nippon Zeon Co., Ltd.
; Bonded AN amount 33%, ML center value 50) ・ ・ 100 parts by weight Reinforcing agent: Precipitated silica (Nip seal VN3 manufactured by Tosoh Silica Industry Co., Ltd.) ・ 14 parts by weight
: Graphite (particle size 5μm)
(Nippon Electric-Graphite A-0 manufactured by Bonn) ・ ・ 35 parts by weight
: Graphite (particle size 10 μm)
(Graphite G-6S, manufactured by Chuetsu Graphite Industry Co., Ltd.) 35 parts by weight
: Acetylene black (Denka Black granule manufactured by Denki Kagaku Kogyo Co., Ltd.)
・ ・ 35 parts by weight Vulcanization accelerator: Zinc flower (Zinc oxide, manufactured by Sakai Chemical Industry Co., Ltd.) ・ ・ 5 parts by weight
: Stearic acid (Stearan TST manufactured by Miyoshi Oil & Fat Co., Ltd.)
.. 1 part by weight anti-aging agent: TMDQ (2,2,4-trimethyl-1,2-dihydroquinoline polymer)
(Seiko Chemical non-flex RD) ・ ・ 2 parts by weight
: IPPD
(N-isopropyl-N'-phenyl-p-phenylenediamine)
(Antage 3C manufactured by Kawaguchi Chemical Co., Ltd.) ・ ・ 2 parts by weight Processing aid: Wax (Suntech R, Seiko Chemical Co., Ltd.) ・ ・ 1.5 parts by weight Plasticizer: Phenyl ester of alkyl sulfonic acid
(Melan Mall made by LANXESS) ・ ・ 15 parts by weight
: Liquid nitrile rubber (NBR)
(Nipol 1312 manufactured by Nippon Zeon Co., Ltd.) 30 parts by weight Vulcanizing agent: Sulfur (colloidal sulfur manufactured by Tsurumi Chemical Co., Ltd.) 1 part by weight Vulcanizing accelerator: TMTM (tetramethylthiuram monosulfide)
(Accelerator TS manufactured by Kawaguchi Chemical Industry Co., Ltd.) 1.65 parts by weight
: MBTS (dibenzothiazyl disulfide)
(Nouchira DM manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) ... 2.2 parts by weight

  Kneader kneading is performed on all raw materials except the above vulcanizing agent and vulcanization accelerator, a master batch is prepared at a discharge temperature of 100 ° C., and then the vulcanizing agent and vulcanization accelerator are mastered by roll kneading. It was added to the batch to prepare the desired rubber composition. A test sample was prepared by press vulcanizing the rubber composition at a vulcanization temperature of 180 ° C. for 6 minutes.

<Evaluation method>
1. Workability Kneader kneadability and roll processability were evaluated.

  The evaluation criteria were ○ if the kneader kneadability was good and x if it was poor. If the roll processability is very good, it is evaluated as “Good”, if it is appropriate (a level that causes no problem in practical use), “Floating”, “adhesion”, etc. are noticeable. (Float) indicates that the float appears remarkably, and (Viscosity) indicates that the adhesion appears remarkably.

2. Mooney scorch test In accordance with JIS K6300, the test temperature was 125 ° C., the preheating time was 1 minute, and the test was conducted with an L-shaped rotor, and the minimum Mooney viscosity Vm and scorch times t5 and t35 were determined.

3. Tensile test and hardness test The tensile test was based on JIS K6251 and the hardness test was measured based on JIS K6253.

4). Compression set test The compression set after heat aging at 100 ° C. for 70 hours was measured with a large test piece in accordance with JIS K6262.

5. Dynamic viscoelasticity measurement Initial strain 10%, frequency 10Hz, dynamic strain 7%, measured at a temperature of 25 ° C using a viscoelastic spectrometer.

6). Heat dissipation test The test method of the heat dissipation test will be described with reference to FIG.

  A thermocouple 23 (Keyence Co., Ltd., multi-input data) set on the upper part of a compression ball by leaving a large test piece 22 on an 80 ° C. hot plate 20 (hot plate device 21: Rotorless Mooney Viscometer RLM-1 manufactured by Toyo Seiki Seisakusho) The temperature reached after 1 hour was measured by the collection system. In actual measurement, since the reached temperature of the rubber becomes constant after about 30 minutes, the average reached temperature from 30 minutes to 1 hour after the start of measurement was defined as the reached temperature after 1 hour. The temperature reached and the temperature of the hot plate were also measured at the same time to correct the ultimate temperature.

A: Rubber arrival temperature B: Hot plate measurement temperature C: Measurement air temperature
Corrected rubber arrival temperature = A + (80−B) − (C−average temperature from all measurements)
The corrected rubber temperature was calculated by the following formula.

Example 2
A rubber sample was prepared in the same manner as in Example 1 except that 70 parts by weight of G-6S alone was added from the combined use of A-0 and G-6S, and an evaluation test was performed.

Example 3
A rubber sample was prepared and evaluated in the same manner as in Example 1 except that 70 parts by weight of G-6S alone and 65 parts by weight of acetylene black were added from the combined use of A-0 and G-6S. A test was conducted.

Example 4
A rubber sample was prepared in the same manner as in Example 1 except that 105 parts by weight of G-6S alone was added from the combination of A-0 and G-6S, and an evaluation test was performed.

Comparative Example 1
A rubber sample was prepared in the same manner as in Example 1 except that no graphite was used and 105 parts by weight of acetylene black was added, and an evaluation test was performed.

Comparative Example 2
A rubber sample was prepared in the same manner as in Example 1 except that 105 parts by weight of A-0 alone was added from the combined use of A-0 and G-6S, and acetylene black was not used. It was.

Comparative Example 3
A rubber sample was prepared in the same manner as in Example 1 except that 105 parts by weight of G-6S alone was added from the combined use of A-0 and G-6S, and acetylene black was not used. It was.

Comparative Example 4
In Example 1, without using graphite and acetylene black, a rubber sample was prepared in the same manner as in Example 1 except that 105 parts by weight of carbon black (Show Black N330 manufactured by Cabot Japan Co., Ltd.) was added, and an evaluation test was performed.

Comparative Example 5
A rubber sample was prepared in the same manner as in Example 1 except that 105 parts by weight of magnesium oxide (Pyroxuma 5301 manufactured by Kyowa Chemical Industry Co., Ltd.) was added without using graphite and acetylene black.

Comparative Example 6
In Example 1, a rubber sample was prepared in the same manner as in Example 1 except that 350 parts by weight of magnesium oxide (Pyroxuma 5301 manufactured by Kyowa Chemical Industry Co., Ltd.) was added without using graphite and precipitated silica, and an evaluation test was performed. .

Comparative Example 7
A rubber sample was prepared and evaluated in the same manner as in Example 1 except that 70 parts by weight of G-6S alone and 5 parts by weight of acetylene black were added from the combined use of A-0 and G-6S. A test was conducted.

Comparative Example 8
A rubber sample was prepared and evaluated in the same manner as in Example 1 except that 5 parts by weight of G-6S alone and 35 parts by weight of acetylene black were added from the combined use of A-0 and G-6S. A test was conducted.

  Table 1 shows the composition and evaluation results of Examples and Comparative Examples.

<Evaluation>
Preferred test values for each evaluation test are as follows.

2. Mooney viscosity: 60M or less Hardness: 75 or less 4. Compression set: within 36% Dynamic viscoelasticity tan δ: 0.3 or more Heat dissipation: 60 ° C. or higher From Table 1, Examples 1, 2, 3, and 4 show preferable values for heat dissipation, other physical properties, and workability.

  In Comparative Example 1, rubber hardness and Mooney viscosity are increased, and deterioration of workability is observed.

  In Comparative Example 2, Comparative Example 3, Comparative Example 7 and Comparative Example 8, the heat dissipation was slightly lower than the expected value.

  In Comparative Example 4, the heat dissipation performance was considerably lower than the expected value.

  In Comparative Example 5, the compression set was extremely deteriorated and no improvement in heat dissipation was observed.

  In Comparative Example 6, although heat dissipation was very good, it was difficult to maintain compression set, and the physical property values deteriorated.

The figure which shows the state which fixed the mount of one Embodiment of this invention to the motor and the bracket. Sectional view of the mounting portion of FIG. Diagram showing thermal conductivity measurement method

Explanation of symbols

1: Motor 2: Motor fixing mount
3: Bracket
4: Anti-vibration rubber 5: Plate 5a: Screw hole 6: Operating shaft
7: Insertion hole 20: Hot plate 21: Hot plate device 22: Large test piece (test piece)
23: Thermocouple

Claims (1)

For fixing a motor, characterized in that the anti-vibration rubber comprising an NBR composition containing 10 to 120 parts by weight of graphite and 10 to 80 parts by weight of acetylene black is sandwiched between plates per 100 parts by weight of NBR rubber . mount.

Images