JPH0637579B2 - Anti-vibration rubber manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used for a vibration-proof elastic support provided in an engine mount portion of an automobile and a vibration-proof sheet laid to prevent vibration of a compressor. The present invention relates to a method for producing a vibration-proof rubber.

[Conventional technology]

In this type of anti-vibration rubber, compounding reinforcing fibers into the rubber is a known technique, and is disclosed in JP-B-47-7.
137 and Japanese Patent Laid-Open No. 59-4636,
It is disclosed that the reinforcing fibers are short fibers having high strength, and the short fibers are kneaded into rubber.

In addition, as a short fiber which is recently kneaded into rubber as described above,
Aramid (aromatic polyamide) fibers, which have high strength, high elastic modulus and low density, are often used.

[Problems to be solved by the invention]

However, the conventional anti-vibration rubber disclosed in Japanese Patent Publication No. 47-7137 has a thickness of 2 to 50 μm.
m, generally 10 to 20 μm, was simply dispersed in the rubber as it was, and the short fibers merely served as a reinforcing material.

Further, since the surface of the above-mentioned aramid fiber is chemically inactive, in order to enhance the bondability with the rubber when compounded in rubber, low temperature plasma or resorcin It is said to require surface treatment with formalin latex (RFL), and therefore
When the above-mentioned aramid fiber is used as the short fiber, there is a problem that an extremely expensive facility is required, the facility cost is high, the treatment cost is high, and the production efficiency is low due to the increase in the number of steps. . In addition, since the short fibers to be blended in the rubber base material are surface-treated in advance, the wettability between the rubber base material and the short fibers is poor, and the short fibers are not uniformly dispersed in the rubber base material. The vulcanization unevenness of the rubber occurs due to the mixture of the narrowed portion and the portion having a low fiber dispersion ratio. Therefore, the composition of the anti-vibration rubber becomes inhomogeneous, and a fatal drawback is exposed for the anti-vibration rubber that a constant anti-vibration effect cannot be obtained.

The present invention has been made in view of the above circumstances, while aiming to reduce manufacturing costs such as equipment costs and processing costs and improve manufacturing efficiency, short fibers are uniformly dispersed in a rubber base material to form fibers. It is an object of the present invention to provide a method for producing a vibration-proof rubber that can promote fibrillation and obtain a vibration-proof rubber excellent not only in mechanical properties but also in physical properties.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the method for producing a vibration-proof rubber according to the present invention includes a mixture containing a polar group-containing rubber as a base material,
A short fiber having an amide bond is left untreated on its surface 1
˜20% by weight and primary kneading to cut and open the short fibers and disperse in the mixture, and then:
It is characterized in that the vulcanizing agent is dispersed and the short fibers are oriented by secondarily kneading the mixture containing the short fibers in such a dispersed state with the vulcanizing agent.

[Operation] According to the present invention, short fibers whose surface has not been treated are added to a mixture containing rubber as a base material and kneaded. Therefore, manufacturing costs such as equipment costs and processing costs required for surface treatment of short fibers are reduced. Not only can it be significantly reduced, but the production efficiency can be improved by omitting the surface treatment step. In addition, since it is a short fiber that has not been surface-treated, it has good wettability with both when it is added to the mixture, and the short fibers are uniformly dispersed in the mixture and there is no uneven vulcanization. An anti-vibration rubber having various compositions can be obtained. Moreover, during the kneading of the mixture of the short fiber and the rubber as the base material, the friction between the two causes the short fiber to be cut and opened to promote fibrillation, and the surface of the short fiber is activated by such fibrillation. Since the polar group of the rubber interacts with the activated surface, the binding force between the short fiber and the mixture containing the rubber as the base material is increased, the load is increased, and the fatigue resistance is also improved. Further, since the vibration energy is consumed by the friction between the fibrillated short fibers, it is also excellent in soundproofing and vibrationproofing.

[Example] Hereinafter, an example of a method for producing a vibration-proof rubber according to the present invention will be described. FIG. 1 is a flow chart showing the manufacturing process of the vibration-proof rubber of Examples 1 and 2 described below, and the procedure of extracting fibrillated short fibers and various physical property tests.

Example 1 As shown in Table 1 below, Example 1 is a carboxylated nitrile rubber Nipol 1072 manufactured by Nippon Zeon Co., Ltd. (hereinafter, c-NBR) as a rubber having a polar group as a base material.
Is added to a mixture A obtained by adding a compound such as carbon to this c-NBR, and is Kevlar # 2 as shown in an electron micrograph in FIG. 2 which is an aramid fiber of DuPont.
This is a composition in which 15% by weight of the short fibers C of 9 was left untreated on the surface.

The short fiber C of Kevlar # 29 has a fiber length of 5 mm and a fiber diameter of 12 μm. The Kevlar # 29 short fibers C have a columnar microfibril structure, and are easily fibrillated by being primarily kneaded with the mixture A containing the c-NBR as a base material by a Banbury mixer, so that the mixture A contains Disperse into. Therefore, the short fibers C are contained in the mixture A in this dispersed state, and the surface is cracked due to cracks. Then, the vulcanizing agent B is added to the mixture A containing the short fibers C in this way, and the secondary kneading is performed along with the roll-out by the open roll to disperse the vulcanizing agent B and orient the short fibers C. I do. Then, after rolling out in this manner, the vibration-proof rubber of Example 1 can be obtained by die press vulcanization molding under the conditions of a temperature of 160 ° C., a pressure of 40 kg / cm ² , and a time of 55 minutes.

FIG. 3 shows that the kneading time of the mixture A containing c-NBR as a base material and the supporting fiber C as described above by the Banbury mixer was 2.5 minutes for one cycle, and this cycle was repeated twice, ten times, respectively. Total time obtained by repeating 20 times,
That is, Example 1 obtained as 5 minutes, 25 minutes, and 50 minutes
For the three types of anti-vibration rubbers corresponding to, the stress-strain curves obtained when the tensile angles with respect to the grain direction were 0 °, 45 ° and 90 °, respectively, and the comparative examples shown in Table 1 containing no short fibers The stress-strain curve of the anti-vibration rubber of 1 is shown. As is clear from FIG. 3, the anti-vibration rubber of the present invention containing short fibers shows a higher stress than that containing no short fibers at any kneading time, and the load load You can see that

4 (a), (b), and (c) show three types of anti-vibration rubbers corresponding to Example 1, and after the kneading with the Banbury mixer was completed, the short fibers in which fibrils were generated by this kneading were extracted. It is an electron micrograph that I saw. These Figure 4 (a),
As is clear from (b) and (c), the short fibers are cut and opened as the kneading time is lengthened, and the fibrillation of the submicron order is progressing, and the stress shown in FIG. From the strain curve, it can be seen that the more the fibrillation progresses, the larger the applied load becomes.

FIGS. 5 (a), (b), and (c) show the tensile fracture surfaces of each of the three types of anti-vibration rubbers corresponding to the first embodiment in the tensile test in the grain direction. It is the taken electron micrograph. As shown in FIGS. 5 (a), (b) and (c),
Extend the kneading time to promote fibrillation of short fibers, and
It is observed that the more the cracked fine short fibers are dispersed in the mixture containing NBR as the base material, the smoother the fracture surface becomes and the higher the fatigue resistance is.

Next, as shown in FIG. 6, the vibration-proof rubber of Example 1 and the vibration-proof rubber of Comparative Example 1 containing no short fibers shown in Table 1 were respectively used.
Immerse it in toluene for 8 hours, then width, depth,
It is a comparative table of the swelling test which measured the height direction and the volume and showed the increase rate with respect to the initial value. As is clear from FIG. 6, the increase rate of Example 1 is smaller than that of Comparative Example 1 regardless of which values are compared, and the vibration-proof rubber of Example 1 has a high bonding strength and weather resistance. It turns out to be excellent.

(Example 2) Next, c-NBR in Example 1 described above as a base material.
An example of using Nipol 1032 (hereinafter referred to as NBR), a nitrile rubber manufactured by Nippon Zeon Co., in place of First, the same compound as in the case of using c-NBR as the base material in Example 1 was added, and c-NBR was changed to N in Table 1 described above.
A mixture A ′ is obtained which has just been replaced by BR. Then, the short fibers C of Kevlar # 29 were added to this mixture A ′ under the same conditions as in Example 1 and the surface thereof was left untreated, and the mixture was subjected to primary kneading. Subsequent kneading yields three types of anti-vibration rubber with different kneading times.

FIG. 7 is based on the c-NBR shown in FIG. 3, which is obtained by setting the pulling angles for the grain direction to 0 °, 45 ° and 90 ° for these three types of anti-vibration rubber. The stress-strain curve corresponding to the case of the anti-vibration rubber and the stress-strain curve of the anti-vibration rubber which uses NBR which does not contain a short fiber as a base material are shown.

This FIG. 7 also shows that the anti-vibration rubber containing the short fibers according to the present invention has a higher stress than in the case where the short fibers are not contained. However, when comparing FIG. 3 and FIG. 7, the anti-vibration rubber having the c-NBR as the base material shown in FIG. 3 is better than the anti-vibration rubber having the NBR as the base material shown in FIG. It can be seen that higher stress is shown and the decrease in stress due to the tension angle is gentle. This is because the surface of the short fibers activated by the fibrillation is c-NBR, whereas only the CN group in NBR interacts as a polar group in the anti-vibration rubber of Example 2 using NBR as a base material. In the antivibration rubber of Example 1 as the base material, it is presumed that the carboxyl group in the rubber molecular chain of c-NBR also interacts with the surface of the short fibers to further increase the binding force between the rubber and the short fibers. To be done.

8 (a), (b), and (c) are electron micrographs of the fibril-formed short fibers extracted in the mixture A ', which are c-NBR.
This corresponds to FIGS. 4 (a), (b), and (c) when using as a base material. In addition, FIGS. 9 (a), (b) and (c) show tensile tests in the grain direction on three types of vibration-proof rubbers obtained by changing the kneading time of the mixture A'and short fibers. FIG. 5 is an electron micrograph of the tensile fracture surface, showing the case of using c-NBR as a base material.
It corresponds to (a), (b), and (c). Further, FIG. 10 shows a vibration-proof rubber of Example 2 and a vibration-proof rubber of Comparative Example 2 containing the same mixture A ′ and vulcanizing agent B as those of the vibration-proof rubber of Example 2 but containing no short fiber. Were soaked in toluene for 48 hours respectively, and then the width direction, the depth direction, the height direction, and the volume were measured, and in the comparison table of the swelling test showing the rate of increase with respect to the initial value of each vibration-proof rubber, This corresponds to FIG. 6 in the first embodiment.

As shown in FIGS. 8 (a), (b) and (c) to FIG. 10, even when the mixture A ′ containing NBR as the base material was used, the short fiber fibril formation was caused with the lapse of kneading time. Progresses (see FIGS. 8 (a), (b), and (c)), and along with this, improvement in fatigue resistance is recognized (see FIGS. 9 (a), (b), and (c)). Further, the anti-vibration rubber of Example 2 has a higher binding force than that of Comparative Example 2, and when the same mixture A ′ is used, the one containing fibril-formed short fibers is far superior in weather resistance. I understand.

As described above, the anti-vibration rubber according to the present invention uses NB as the base material.
Even when R is used, a very remarkable effect on the physical properties can be obtained.

Next, in the method for producing a vibration-proof rubber according to the present invention, the content of the short fiber having an amide bond, which is mixed in the mixture containing the rubber as a base material, will be described. FIG. 11 shows that 20% by weight of short fibers of Kevlar # 29 were added to the mixture A containing the c-NBR as a base material and used in Example 1, respectively.
The stress-strain curve was obtained for the vibration-proof rubber according to the present invention that was kneaded at 5% by weight, 10% by weight and 5% by weight, with the tensile angles to the grain direction being 0 ° C and 90 ° C. As shown in FIG. 11, it is observed that the tensile strength increases as the content of short fibers increases. However, in the method for producing the vibration-insulating rubber according to the present invention, when the content of the short fibers is more than 20% by weight, the elongation tends to be extremely small, and the vibration-proofing function tends to deteriorate. In addition, there is a phenomenon that it becomes difficult to uniformly disperse the short fibers. On the other hand, if the content of the short fibers is less than 1% by weight, the effect of containing the short fibers does not occur. Therefore, by setting the content of the short fibers to be 1 to 20% by weight, the effect as the anti-vibration rubber according to the present invention can be obtained.

It should be noted that the present invention is not limited to the above examples, and the base rubber has other polar groups such as chloroprene rubber, epichlorosedrin rubber, chlorosulfonated polyethylene rubber and polyurethane rubber. Rubber can also be used. Further, as long as the short fibers are fibers having an amide bond having a fibril structure, other fibers such as silk may be used.

〔The invention's effect〕

As described above, in the method for producing the vibration-proof rubber according to the present invention, the mixture of the rubber as the base material is kneaded by adding the short fibers which have not been subjected to the surface treatment. The manufacturing cost such as the processing cost can be remarkably reduced, and the manufacturing efficiency can be improved by omitting the surface treatment step. In addition, since it is a short fiber that has not been surface-treated, it has good wettability with both when it is added to the mixture, and evenly disperses the short fibers in the mixture to eliminate the occurrence of uneven vulcanization and to achieve a uniform An anti-vibration rubber having various compositions can be obtained. Moreover, during the kneading of the mixture of the short fibers and the rubber as the base material, the friction between the two causes the short fibers to be cut and opened to promote fibrillation, and the surface of the short fibers is activated by such fibrillation. , The polar group of rubber interacts with the activated surface, so that the binding force between the mixture of short fiber and rubber as the base material can be increased, the load load can be increased, and the fatigue resistance can be improved. Since it can be manufactured, and has high strength and excellent weather resistance, it can be effectively used as a wide range of anti-vibration rubber such as anti-vibration elastic support equipment mounted on an engine mount part or the like. Further, since the vibration energy is consumed by the friction between the fibrillated short fibers, it also has an excellent soundproofing and vibrationproofing effect.

[Brief description of drawings]

FIG. 1 is a flow chart showing the manufacturing process of the vibration-proof rubber of Examples 1 and 2, FIG. 2 is an electron micrograph of short fibers of Kevlar # 29, and FIG. 3 is the stress of the vibration-proof rubber of Example 1. Strain curves, FIGS. 4 (a), (b), and (c) are electron micrographs of fibril-formed short fibers, and FIGS. 5 (a), (b), and (c) are the results of Example 1. An electron micrograph showing the shape of short fibers on the tensile fracture surface of the vibration proof rubber, FIG. 6 is a table showing the results of the swelling test of the vibration proof rubber of Example 1, and FIG. 7 is the stress of the vibration proof rubber of Example 2. −
Strain curves, FIGS. 8 (a), (b), and (c) are electron micrographs of fibril-formed short fibers, and FIGS. 9 (a), (b), and (c) are vibration isolation of Example 2. An electron micrograph showing the shape of the short fibers on the tensile fracture surface of the rubber, FIG. 10 is a table showing the results of the swelling test of the vibration isolating rubber of Example 2, and FIG. 11 is a diagram showing the method for producing the vibration isolating rubber according to the present invention. FIG. 3 is a stress-strain curve of a vibration-proof rubber produced by changing the content of short fibers.

Claims (2)

[Claims] A short fiber having an amide bond is added to a mixture containing a rubber having a polar group as a base material in an amount of 1 to 20% by weight without surface treatment, and the mixture is primarily kneaded to obtain the short fiber. Dispersing the vulcanizing agent and short fibers by cutting and opening the fibers to disperse them in the mixture, and then adding a vulcanizing agent to the mixture containing the short fibers in such a dispersed state and secondarily kneading the mixture. A method for producing a vibration-proof rubber, which comprises performing the orientation of 2. The method for producing an antivibration rubber according to claim 1, wherein aramid fibers having a columnar microfabric structure are used as the short fibers.