KR20190108992A - Vibration Proof Rubber Composition - Google Patents

Abstract

The present invention relates to a vibration proof rubber composition and, more specifically, to a vibration proof rubber composition preventing degradation of physical properties while maximizing vibration isolation and maintaining durability by limiting the specific types of butadiene rubber and the content with natural rubber. According to the present invention, the vibration proof rubber composition comprises: 100 parts by weight of raw rubber consisting of 55-80 wt% of natural rubber and 20-45 wt% of 1,2-butadiene rubber; 35-55 parts by weight of carbon black; 4.5-8 parts by weight of a cross-linking activator; 0.7-1.0 parts by weight of sulfur; 1.5-1.9 parts by weight of a cross-linking accelerator; 2-3.5 parts by weight of an anti-aging agent; and greater than 0 and less than 3 parts by weight of a plasticizer.

Description

Vibration Proof Rubber Composition

The present invention relates to an anti-vibration rubber composition, by limiting the specific type of butadiene rubber and the content of the natural rubber, to an anti-vibration rubber composition to maximize the vibration insulation and at the same time prevent the degradation of physical properties to maintain durability.

Anti-vibration rubber in the automotive field refers to rubber used to prevent vibration noise (NVH). Anti-vibration rubber prevents the transmission of vibration from the motor, engine, etc. to the outside by using the property of absorbing the kinetic energy of rubber well. Bushes such as stabilizer bar bushes and suspension bushes in the automotive field must have sufficient durability against large external force applied from the outside to improve the NVH performance of the car to improve ride comfort.

In particular, the anti-vibration rubber used in the suspension must satisfy sufficient durability against the large external force applied from the outside and satisfy the opposite characteristics of excellent vibration insulation effect. Higher spring characteristics of the bush provide better handling, while NVH (Noise, Vibration, Harshness) performance is reduced, while lower spring characteristics of the bush improve NVH performance, resulting in better ride comfort, while handling and ride. The performance is degraded and you should tune and use it properly.

In addition, rubber bushes, which connect the links constituting the vehicle suspension and serve to absorb vibrations generated on the road surface, are used to support the vehicle and absorb vibrations transmitted from various directions. At this time, since the high load is applied to these rubber bushes, the hardness of the rubber bush is intentionally increased in order to improve driving and handling performance of the vehicle. Therefore, in order to manufacture a rubber bush of high hardness, a method in which a large amount of sulfur is used as a crosslinking agent or a large amount of filler is used. However, when a large amount of sulfur is added, the crosslinked structure is destroyed by heat generated during vulcanization. Therefore, the method of increasing the filler, such as carbon black, has been mainly used.

However, when a large amount of carbon black is blended, there is a problem in that a dispersion of the quality is generated because the mixing with the rubber is not performed well to obtain an even dispersion of the filler. In addition, when a certain amount or more of the filler is compounded, a phenomenon in which the physical properties thereof are deteriorated appears, and thus there is a problem such that it is difficult to satisfy the required performance of the product.

Furthermore, sulfur, vulcanization accelerators, activators, antioxidants, dispersants, processing oils and carbon blacks are included in the raw material rubbers using natural rubber together with synthetic rubber such as styrene butadiene rubber in specific content ratios. Rubber compositions for bushes having improved properties such as damping properties have also been used.

However, the rubber composition is a high Cis BR rubber having a cis content of 98% or more, and the molecules have very low spin-rotation energy and thus have high motility and repulsion property, thereby improving the rubber's dynamic performance, that is, vibration insulation performance. Due to physical mixing due to natural rubber, physical properties were degraded due to phase dualization.

In addition, MB (2-mercaptobenzimidazole) used as an anti-aging agent in the prior art affects the crosslinking properties due to reaction with the accelerator during vulcanization, adversely affecting the final rubber material quality. Accordingly, it is necessary to improve the rubber physical properties to maintain the vibration insulation performance while maintaining durability.

Accordingly, consideration of a composition to which other types of BR rubbers are added is required, and the present invention is devised to maximize the vibration insulation and to prevent the deterioration of rubber properties to maintain durability.

The present invention has been made to solve the above-mentioned problems of the prior art, to maximize the vibration insulation, but to a rubber composition that prevents the deterioration of rubber properties to maintain the durability, the detailed types of butadiene rubber (BR) and natural The purpose is to improve the physical properties by limiting the content with the rubber.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description of the present invention. .

According to the present invention for solving the above problems of the prior art, 100 parts by weight of the raw rubber consisting of 55 to 80% by weight of natural rubber and 20 to 45% by weight of 1,2-butadiene rubber; 35 to 55 parts by weight of carbon black; 4.5 to 8 parts by weight of crosslinking activator; Sulfur 0.7 to 1.0 parts by weight; 1.5 to 1.9 parts by weight of crosslinking accelerator; Antioxidants 2 to 3.5 parts by weight; And more than 0, not more than 3 parts by weight of a plasticizer; It provides a dustproof rubber composition comprising a.

In the present invention, the carbon black is preferably a mixture of FEF and HAF.

In the present invention, the FEF is preferably 25 to 35 parts by weight.

In the present invention, the HAF is preferably 10 to 20 parts by weight.

In the present invention, the crosslinking activator preferably comprises zinc oxide and stearic acid.

In the present invention, the zinc oxide is preferably 3 to 5 parts by weight.

In the present invention, the stearic acid is preferably 1.5 to 3 parts by weight.

In the present invention, the content ratio of the sulfur / crosslinking accelerator is preferably 0.37 ~ 0.66.

In the present invention, the crosslinking accelerator preferably includes CBS, which is a primary crosslinking accelerator, and TMTD, which is a secondary crosslinking accelerator.

In the present invention, the CBS is preferably 0.5 to 0.7 parts by weight.

In the present invention, the TMTD is preferably 1 to 1.2 parts by weight.

In the present invention, the anti-aging agent preferably includes TMQ and IPPD.

In the present invention, the TMQ is preferably 1.5 parts by weight.

In the present invention, the IPPD is preferably 1 to 2 parts by weight.

According to the anti-vibration rubber composition of the present invention, by limiting the content of 1,2-BR and NR to the suspension bush, it provides an effect of improving vibration insulation, increasing rubber properties and improving low temperature elasticity.

1 is a graph showing the results of evaluating the viscoelastic properties of the examples according to the present invention and the comparative example according to the prior art.
Figure 2 is a graph showing the repeated fatigue failure step of the rubber.
Figure 3 is a graph showing the repeated fatigue failure step of the embodiment according to the present invention and the comparative example according to the prior art.

Hereinafter, preferred embodiments of the present invention will be described in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described herein are only one of the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, and various equivalents and modifications that may substitute them at the time of the present application may be used. It should be understood that there may be.

In the rubber composition, the chemical basis for mixing NR / BR is that BR rubber sends Tg at a lower temperature than pure NR, while expanding the rubbery region of the polymer and increasing the flexibility and elasticity region.

Butadiene rubber used in the past is Cis-1,4-Nd (Neodymium Butadiene), a high Cis BR rubber with a cis content of 98% or more. It is effective to increase, but physical incompatibility in the composition is inferior in the physical properties of the rubber (Phase) dualization (Phase) there was a problem that the physical properties decrease.

In addition, the problems according to the prior art (1,4-BR), the physical properties in terms of physical mixing in a single polymer phase (Phase) dualization of the physical properties, and in terms of dynamic properties of the crystallization zone in the low temperature region modulus There was no particular advantage for the reduction. In addition, the presence of the shoulder region has a disadvantage in that the vibration at low temperature / high frequency.

In order to solve this problem, the present invention is a mixture of 1-2BR rubber, the 1,2-BR rubber while maintaining the advantages of the conventional butadiene rubber as it is, while improving the mixing properties and NR and improved physical properties and low temperature There is an advantage of improving elasticity.

That is, the present invention relates to an anti-vibration rubber composition that maximizes vibration insulation and prevents degradation of rubber properties to maintain durability.

In other words, the present invention uses butadiene rubber as 1,2-BR, rather than conventional 1,4-BR. The 1,2-BR rubber maintains the conventional advantages as it is, and has the advantage of improving rubber properties and improving low temperature elasticity by improving the mixing with natural rubber.

Table 1 below shows the rubber compositions of Examples 1 to 4 according to the present invention and the prior art.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example stomach
synthesis
article
castle Polymer NR 70 50 85 100 70 1,2-BR - 50 15 - 30 1,4-BR 30 - - - - Carbon black HAF (N330) 22 20 20 20 20 FEF (N550) 23 25 25 25 25 Aging
Inhibitor TMQ 2 1.5 1.5 1.5 1.5 MB One - - - - IPPD - One One One One 6PPD 1.5 - - - - Antilux500 One 2 2 2 2 Activator ZnO 5 3 3 3 3 St-acid 2 3 3 3 3 Plasticizer Mineral oil - 3 3 3 3 Sulfur / accelerator Sulfur 1.5 0.7 0.7 0.7 0.7 CBS One 0.5 0.5 0.5 0.5 TMTD - One One One One TBzTD One - - - - Total content (phr) 161 160.7 160.7 160.7 160.7

Raw material rubber according to the present invention is used by mixing natural rubber (Natural Rubber, CV60-based) and butadiene rubber (Butadiene Rubber), the raw material 100 weight of the rubber consisting of 55 to 80% by weight and 20 to 45% by weight of butadiene rubber It is desirable to disclaim. At this time, the butadiene rubber is preferably 1,2-butadiene rubber (1,2-vinyl content: 10% or more / 1,4-cis content: less than 40%).

At this time, the 1,2-BR rubber is preferably used in 20 to 45% by weight. When the 1,2 BR rubber is used in less than 20% by weight, it is difficult to improve the dynamic characteristics unique to BR rubber, that is, decrease the dynamic stiffness, reduce internal heat generation, and when it exceeds 45% by weight, mechanical properties such as tensile strength, elongation and stiffness. This deterioration problem occurs.

Carbon black, a filler according to the present invention, is added to improve the rigidity and dynamic performance, and the FEF (N550 series, d = 42nm, density 20.0 lb / ft3 to 24.0 lb / ft3, oil content 115 cm3 / 100g to 127 cm3 / 100g) ) And HAF (N330 series, d = 32nm, density 22.1 lb / ft 3 to 25.2 lb / ft 3, oil content 96 cm 3 / 100g to 108 cm 3 / 100g) can be used in combination.

The FEF is preferably used in 25 to 35 parts by weight. When less than 25 parts by weight, it is difficult to improve dynamic properties (reduce dynamic rigidity, reduce internal heat generation) and deteriorate moldability during manufacturing. If more than 35 parts by weight, there is a disadvantage that the mechanical properties are lowered.

The HAF is preferably used in 10 to 20 parts by weight. If it is less than 10 parts by weight, mechanical properties are lowered, and if it is more than 20 parts by weight, it is difficult to expect an improvement in dynamic properties.

The crosslinking activator in the dustproof rubber composition according to the present invention may include ZnO (zinc oxide) and Stearic Acid (stearic acid).

The zinc oxide is preferably used in 3 to 5 parts by weight. If it is less than 3 parts by weight, the crosslinking activity is lowered, the mechanical properties and fatigue durability of the formulation is lowered. If it is more than 5 parts by weight, it is difficult to ensure stable blending time and temperature conditions increase the rate of dispersion between formulations.

The stearic acid is preferably used in 1.5 to 3 parts by weight. If less than 1.5 parts by weight, the crosslinking activity is lowered, the mechanical properties and fatigue durability of the formulation is lowered, if more than 3 parts by weight it is difficult to ensure a stable mixing time and temperature conditions there is a problem that the rate of dispersion between formulations increases.

Sulfur, which is a crosslinking medium according to the present invention, is preferably included in an amount of 0.7 to 1.0 parts by weight. In addition, as a crosslinking accelerator according to the present invention, 0.5 to 0.7 parts by weight of N-Cyclohexyl 2-Benzothiazolesulfenamide (CBS) used as a delayed primary crosslinking accelerator and 1 to 1.2 parts by weight of tetramethylthiuram disulfide (TMTD) as an accelerating secondary crosslinking accelerator It is preferable to use a part. It is preferable to use said primary and secondary crosslinking accelerators simultaneously in the composition.

Meanwhile, the content ratio (Sulfur / Accelerator) of sulfur and crosslinking accelerator determines the structure of the crosslinking system. In the case of the effective vulcanization (content ratio <1), the heat resistance of the compound is increased but the fatigue strength is lowered. In the case of general vulcanization (content ratio> 1), the fatigue strength of the compound is increased, but the heat resistance is deteriorated and the anti-effectiveness is increased. In the case of sulfur, the formulation shows intermediate properties.

In the present invention, the sulfur / crosslinking accelerator ratio is preferably 0.37 to 0.66. In other words, the effective vulcanization system is adopted, and the heat resistance is increased at a ratio of 0.75, which is a conventional compound, and the conflicting fatigue strength (physical property) is sufficiently complemented by using 1,2-BR rubber.

The anti-aging agent in the composition according to the present invention may include TMQ (2, 2, 4-Trimethyl-1, 2-dihydroquinoline), IPPD (N-isopropyl-N'phenyl-p-phenylenediamine). Furthermore, Antilux® 500 (Rhein Chemie) may further be included.

The TMQ is preferably 1.5 parts by weight as a strong anti-aging agent without addition reaction with an accelerator. If it is more than 1.5 parts by weight, there is a fear of deterioration of physical properties due to surface blooming. The IPPD is an ozone anti-aging agent has the advantage of excellent stability even at high heat and long-term effect, it is preferable to use in 1 to 2 parts by weight. If it is more than 2 parts by weight, there is a fear of deterioration of physical properties due to surface blooming. The Antilux® 500 is a general purpose paraffinic ozone anti-aging agent is preferably 2 parts by weight.

In addition, a plasticizer in the composition may be added. The plasticizer helps to improve compoundability (compound-ability), additive dispersion, it is preferred to use more than 0 up to 3 parts by weight. If it exceeds 3 parts by weight, there is a fear that the physical properties of the final formulation is lowered.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example Properties
evaluation
result Miga
Properties Tmax (dNm) 7.62 9.97 7.62 6.86 8.15 Tmin (dNm) 1.06 1.35 1.06 1.26 1.20 T90 (min) 3.21 4.19 3.21 3.06 3.56 Ts2 (min) 1.15 1.12 1.15 1.02 1.16 state
Properties Hardness (Hs) 61 65 60 61 60 Tensile Strength (kgf / ㎠) 201 180 226 290 221 Elongation (%) 560 550 640 680 640 Aging
Properties
(70 ℃ / 1000Hr) Hardness change (Hs) 7 8 6 6 6 Tensile Strength Change Rate (%) -7 -26 -18 -15 -18 Elongation rate of change (%) -23 -35 -23 -19 -25 characteristic
evaluation Modulus of elasticity (MPa)
(G '@ 1Hz) -20 ℃ 3.50 0.76 3.07 3.32 1.48 24 ℃ 2.14 0.46 2.35 2.67 1.28 Fatigue Durability Assessment (cycle)
(150N ± 150N, 1Hz, RT) 2465 1999 1850 2532 2861

Table 2 shows the results of evaluation of durability characteristics such as state properties and heat resistance. Comparative Examples 1 to 4 show evaluation results according to the prior art, and it can be seen from Table 2 that the physical properties are significantly lower than those of Examples. That is, when compared with the Comparative Examples 1 to 4, it can be confirmed that the Example shows the most excellent physical properties, vibration performance and fatigue durability.

On the other hand, the anti-vibration rubber composition according to the present invention is preferably a rubber Shore A hardness of 55Hs to 65Hs.

1 is a graph showing the results of evaluating the viscoelastic properties of the examples according to the present invention and the comparative example according to the prior art.

Referring to FIG. 1 in more detail, Comparative Example 1 has a shoulder region where modulus increases at low temperature (-40 to -20 ° C) due to phase dualization of rubber due to the addition of 1,4-BR. do. The shoulder region is a material cause of deterioration of vibration insulation in the low / high frequency region of the component. (3.50MPa@-20℃)

More specifically, Comparative Example 4 is a pure NR composition without the addition of BR rubber, but the low-temperature shoulder region does not appear, but due to the high modulus (2.67 MPa @ 24 ° C) it can be said that there is no effect of improving the vibration insulation.

In Comparative Example 3, 15 parts by weight of 1,2-BR was added, but the low temperature shoulder region did not appear, but there was no improvement.

In Comparative Example 2, 50 parts by weight of 1,2-BR was added, and thus the low temperature shoulder region did not appear, and the modulus change was very low, and thus the vibration was improved. In particular, in Comparative Example 2 it can be confirmed that Table 2 above that the tensile strength is 20% lower than Comparative Example 1.

On the contrary, in the embodiment, the low-temperature shoulder portion was not detected by the addition of 30 parts by weight of 1,2-BR, and showed a very low modulus variation, resulting in a large vibration insulation effect (1.28 MPa @ 24 ° C).

2 is a graph showing the cyclic fatigue failure step of rubber. 2 has a total of five regions. In more detail, the five regions are described as: an extension region in which a sudden decrease in rubber characteristics due to an initial load (displacement), a stable region in which rubber characteristics are found to be stabilized by displacement, and a crack is first generated inside or outside. This is the first crack generation area, the crack propagation area, the crack propagation area where energy accompanies suddenly upon destruction, and the complete crack area where cracks are fully developed by cracks being further enhanced.

Evaluation results according to FIG. 2 are the same as in FIG. 3. Figure 3 is a graph showing the repeated fatigue failure step of the embodiment according to the present invention and the comparative example according to the prior art.

Referring to FIG. 3 in more detail, Comparative Example 1 has a durability of 2465 cycles with a 1,4-BR addition composition. Comparative Example 4 is a pure NR composition without addition of BR rubber, and has a durability of 2532 cycles. Comparative Example 3 has a durability of 1850 cycles with a 15 wt% additive composition of 1,2-BR. Comparative Example 2 has a durability of 1999 cycles with a 50 wt% addition composition of 1,2-BR. In particular, Comparative Example 2 has the largest static characteristic change rate (Δk ′, slope), which can be confirmed that the deterioration is the largest. In contrast, the Example has a durability of 2861 cycles with a 30 wt% addition composition of 1,2-BR, and it is confirmed that the initial crack initiation point (complete break point) is also the slowest.

As such, the present invention relates to an optimal formulation for maintaining long-term durability and improving NVH performance as it relates to the anti-vibration rubber composition of the suspension bush in order to improve vehicle ride comfort, steering stability, and impact shock.

That is, the present invention relates to an anti-vibration rubber composition that maximizes vibration insulation and prevents degradation of rubber properties to maintain durability. According to the present invention, by limiting the content ratio of the butadiene rubber (BR) to the specific type and the natural rubber, there is an advantage that it is possible to improve the deterioration of physical properties that were conventionally inappropriate.

In other words, the present invention uses the 1,2-BR butadiene rubber, not the conventional 1,4-BR, the 1,2-BR rubber maintains the advantages of the prior art, and is mixed with natural rubber It is effective in improving rubber properties and improving low temperature elasticity.

The present invention has been described above in connection with specific embodiments of the present invention, but this is only an example and the present invention is not limited thereto. Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and within the equivalent scope of the technical spirit of the present invention and the claims to be described below. Various modifications and variations are possible.

Claims (14)

100 parts by weight of raw rubber consisting of 55 to 80% by weight of natural rubber and 20 to 45% by weight of 1,2-butadiene rubber;
35 to 55 parts by weight of carbon black;
4.5 to 8 parts by weight of crosslinking activator;
Sulfur 0.7 to 1.0 parts by weight;
1.5 to 1.9 parts by weight of crosslinking accelerator;
Antioxidants 2 to 3.5 parts by weight; And
Plasticizer greater than 0 and 3 parts by weight or less;
Dustproof rubber composition comprising a.
The method of claim 1,
The carbon black is dustproof rubber composition, characterized in that the mixture of FEF and HAF.
The method of claim 2,
The FEF is 25 to 35 parts by weight dustproof rubber composition, characterized in that.
The method of claim 2,
The HAF is dustproof rubber composition, characterized in that 10 to 20 parts by weight.
The method of claim 1,
Wherein the crosslinking activator comprises zinc oxide and stearic acid.
The method of claim 5,
The zinc oxide is dustproof rubber composition, characterized in that 3 to 5 parts by weight.
The method of claim 5,
The stearic acid is dustproof rubber composition, characterized in that 1.5 to 3 parts by weight.
The method of claim 1,
Dust-resistant rubber composition, characterized in that the content ratio of the sulfur / crosslinking accelerator is 0.37 ~ 0.66.
The method of claim 1,
The crosslinking accelerator is a dust-proof rubber composition, characterized in that it comprises a primary crosslinking accelerator CBS and a secondary crosslinking accelerator TMTD.
The method of claim 9,
The CBS is dust-proof rubber composition, characterized in that 0.5 to 0.7 parts by weight.
The method of claim 9,
The TMTD is dustproof rubber composition, characterized in that 1 to 1.2 parts by weight.
The method of claim 1,
The anti-aging agent dustproof rubber composition, characterized in that it comprises TMQ and IPPD.
The method of claim 12,
The TMQ is dustproof rubber composition, characterized in that 1.5 parts by weight.
The method of claim 12,
The IPPD is dustproof rubber composition, characterized in that 1 to 2 parts by weight.

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