KR20120126165A - Rubber compound for car engine mount enhanced vds by mixing epdm with hybrid vulcanization system - Google Patents

Abstract

PURPOSE: A rubber composition for an automotive engine mount is provided to enhance thermal resistance and to maintain a low dynamic ratio by enhancing a dynamic characteristic. CONSTITUTION: A rubber composition for automotive engine mount comprises 0.4-1.5 parts by weight of sulfur, 0.5-3.5 parts of N-cyclohexyl-2-benzothiazyl-sulfenamide, 0.5-3.5 parts of tetramethylthiuram disulfide, 2-8 parts of a peroxide cross-linker, 15-30 parts of SRF(semi-reinforcing furnace) carbon black, 10-20 parts of FEF(fast extrusion furnace) carbon black, and 4-6 parts of paraffinic oil based on an EPDM mixture which blends EPDM 1 which does not include oil and EPDM 2 which includes oil at the weight ratio of 1:3. As additives, 2-7 parts by weight of activated zinc, 1-3 parts of stearic acid, 1-2 parts of SUN 682(Sunprax) and 2-4 parts of 13 C (N-phenyl-N'-isopropyl-p-phenylenediamine) are included.

Description

RUBBER COMPOUND FOR CAR ENGINE MOUNT ENHANCED VDS BY MIXING EPDM WITH HYBRID VULCANIZATION SYSTEM}

The present invention relates to a rubber composition for an automobile engine mount having improved durability by applying a hybrid vulcanization system to EPDM, and more particularly, having a mechanical property equivalent to that of existing natural rubber, and ensuring heat resistance that can be used even at least 140 ° C. The present invention relates to a rubber composition for automobile engine mounts having improved durability by applying a hybrid vulcanization system to EPDM, which satisfies the dynamic magnification characteristics required by the mount and at the same time creep resistance.

In general, the anti-vibration rubber, which supports the engine of the vehicle and serves to suppress the transmission of vibration generated from the engine to the rider, is a very important factor in the technology development related to the noise vibration (N.V.H) of the automobile.

Among them, the engine mount is one of the important parts that must simultaneously have high static stiffness and low dynamic stiffness to suppress the transmission of vibration to support the weight of the engine and the transmission.

For example, engine mounts for automobiles require power plant positioning, flow control, and vibration noise isolation. In particular, it is an important part for minimizing the transmission of the impact generated on the irregular road surface to the vehicle body and increasing the ride comfort and driving stability of the vehicle.

Such an engine mount is advantageous to have a smaller dynamic ratio (dynamic / static characteristic) in order to secure the position of the engine and to suppress vibration transmission, and has a higher attenuation. In addition, due to the characteristics of the engine mount, fatigue resistance is required due to vibration generated on the road surface of the engine and when driving. That is, since repeated heavy loads are input while the vehicle is driving, durability of the rubber to withstand them is required at the same time.

As a result, the engine mount must have technical characteristics that must simultaneously secure low dynamic power, fatigue resistance, heat resistance, and creep resistance.

In order to satisfy such complex requirements, engine mounts have been manufactured using natural rubber having excellent mechanical properties as a basic raw material, and compounds including fillers, vulcanizing agents, vulcanizing agents, anti-aging agents, and the like.

Therefore, the physical properties of the engine mount vary greatly depending on the purity of the natural rubber used and the type of additives.

However, the engine mount of a car is located in a high temperature engine room and is always exposed to high temperatures. Recently, the engine room temperature has risen sharply as environmental requirements such as high performance of the car and regulation of exhaust environment have been strengthened. Engine mounts manufactured from rubber are becoming increasingly difficult to meet heat resistance requirements.

Particularly, in the case of automobiles used in high temperature areas, the use temperature exceeds 100 ℃ and the fatal aging of rubber occurs. Natural rubber contains a double bond that is susceptible to heat, so the range of use does not exceed 100 ℃. Have

Therefore, CR (Chloroprene rubber) and EPDM (Ethylene propylene diene rubber), which have good heat resistance, have been considered as next-response polymers, but are difficult to apply to engine mounts due to mechanical properties, low temperature characteristics, and high dynamic characteristics.

In this regard, Patent Publication No. 10-2004-0000852 "Rubber Composition for Engine Mount" has been disclosed.

The disclosed technique focuses mainly on the heat-resistant part of the above-mentioned disadvantages, and is sulfur (S) as a vulcanizing agent in EPDM, N-Cyclohexyl-2-benzothiazyl-sulfenamide (CBS) and Tetra methylthiuram disulfide (TT) as fillers Carbon black is added to improve heat resistance.

However, the disclosed technology is still disadvantageous in terms of dynamic magnification due to its high dynamic characteristics, and an improvement thereof has been required.

In addition, in order to manufacture an engine mount having long durability and long life, heat resistance and creep resistance must be satisfied. However, the disclosed technology has been insufficient in this regard.

The present invention has been made in view of the above-mentioned problems in the prior art, and has been created to solve this problem, and has the same level of mechanical properties as natural rubber and has heat resistance usable at 140 ° C. or higher, and above all, the dynamic characteristics are improved. It is possible to manufacture engine mounts with excellent vibration suppression ability by maintaining dynamic magnification, and at the same time, it provides excellent durability and rubber composition for automobile engine mounts with improved durability by applying hybrid vulcanization system to EPDM, which can achieve long life with excellent creep resistance. There is a purpose.

The present invention provides a means for achieving the above object, with respect to 100 parts by weight of EPDM blend blending EPDM 1 not containing oil and EPDM 2 including oil in a weight ratio of 1: 3; Sulfur: 0.4-1.5 parts by weight, CZ, TT: 0.5-3.5 parts by weight, peroxide crosslinking agent: 2-8 parts by weight, SRF: 15-30 parts by weight, FEF: 10-20 parts by weight, paraffin oil: 4-6 Including, by weight, other additives, activated zinc: 2-7 parts by weight, stearic acid: 1-3 parts by weight, SUN682 (sunprax): 1-2 parts by weight, 13C (N-Phenyl-N'-isopropyl -p-phenylenediamine): Provides a rubber composition for automobile engine mount applying a hybrid vulcanization system to EPDM, characterized in that the composition is added by 2-4 parts by weight.

In this case, the EPDM includes 4-6 wt% of ethylidene norbornene (ENB) and 50-70 wt% of ethylene, and has a Mooney viscosity of 50 to 60 ml based on the total weight of EPDM.

In addition, the peroxide crosslinking agent is also characterized in that TBPDB (Di-t-butyl peroxy di-siopropyl benzene).

According to the present invention, by applying a hybrid vulcanization system, the mechanical properties are maintained at the same level as natural rubber, but the heat resistance is improved, long life is possible, the dynamic properties are improved, the vibration transmission is excellent, and the creep resistance is improved, and the durability is excellent. The effect which made the engine mount for automobiles possible can be acquired.

Hereinafter, preferred embodiments according to the present invention will be described in detail.

First, EPM refers to a random copolymer composed of ethylene unit (E) and propylene unit (P). Herein, the introduction of a diene monomer as a three component for vulcanization is called EPDM.

The EPDM has various properties such as average molecular weight, molecular weight distribution, ethylene / propylene ratio, type of termonomer, branching, and the like, and thus the physical properties and processability of the final product can be varied. Due consideration should be given to the relationship between structure and physical properties, the appropriate EPDM grade should be selected.

EPDM has been used mainly for weather strips and oil seals based on its excellent ozone resistance, weather resistance and chemical resistance. EPDM, which has a disadvantage in dynamic or damping properties, is applied to engine mounts that require these characteristics. This could not be done.

Therefore, in order to satisfy the requirements of dynamic characteristics and attenuation performance, it is important to select EPDM base polymer, and to select and mix vulcanizing agent and filler in what kind and to what content.

The overall characteristics of EPDM are excellent ozone resistance, chemical resistance, heat resistance, etc. because there is no double bond in the main chain. In particular, compressive shrinkage, high temperature performance, low temperature flexibility, and the like largely depend on the composition and blending of the polymer.

On the other hand, EPDM contains a small amount of unsaturated groups in the molecular side chain, but the vulcanization rate is slow due to less unsaturation compared to natural rubber and diene rubber, and has a disadvantage in that fatigue performance and dynamic properties are lower than those of natural rubber. Therefore, the development of EPDM rubber compositions for engine mounts aims at improving the overall physical properties required for automotive engine mounts through the selection of base polymers and compound designs.

In addition, the physical properties of EPDM rubber are greatly influenced by EPDM grades and vulcanization systems.

EPDM's vulcanization systems can be broadly divided into sulfur vulcanization and peroxide vulcanization.

EPDM applied by Sulfur vulcanization determines heat resistance and durability according to sulfur content and ENB content. Less sulfur is used to improve heat resistance, but the durability is lowered. Therefore, accelerator and compounding ratio must be properly adjusted. do.

In addition, when the ENB content is reduced, the heat resistance is improved, but due to the decrease in the crosslinking point, it is necessary to adjust appropriately to improve the crosslinking density by reducing the durability of mechanical properties.

On the other hand, the peroxide vulcanization method has better heat resistance and compression set than the vulcanization method, but shows low mechanical properties and tear strength.

Therefore, in order to use EPDM as an anti-dust rubber for engine mount, it is necessary to develop an optimum vulcanization system to satisfy mechanical properties, heat resistance, and creep resistance at the same time, and in the present invention, a hybrid method using a vulcanization method and a peroxide method for this purpose. Was adopted.

In addition, EPDM rubber according to the present invention is used by blending two different grades of KEP (Kumho Polychem), ENB (ethylidene norbornene) content is 4 ~ 6wt%, ethylene (ethylene) content Silver 50 ~ 70wt%, Mooney viscosity (mooney viscosity) of 50 ~ 60ML is used.

In this case, the first grade (oil) means a rubber to which 100PHr is added.

These EPDM rubbers have high molecular weight and ethylene content in order to achieve excellent mechanical properties, and also use ENB type diene monomer in order to vary the vulcanization rate and accelerator selection range.

In this case, the ENB type diene monomer is preferably a rubber with a low ENB content to improve the heat resistance.

To this end, ENB (5-ethylkdene-2-norbornene), one of the structural factors of EPDM, increases the crosslinking point during sulfur vulcanization as the content increases, causing deterioration of properties such as scorch stability, heat resistance and ozone resistance. The low ENB content was selected, and the composition ratio of ethylene and propylene is a factor that greatly affects the processability of unvulcanized rubber and the physical properties of vulcanized rubber. When the ethylene content is less than 50wt%, the mechanical properties decrease. In addition, when it exceeds 70wt%, the low temperature dynamic characteristics are deteriorated, so EPDM containing 50 to 70wt% of ethylene is selected as the raw material rubber to increase the mechanical strength and the filling property as much as possible.

In addition, blending two different grades of EPDM rubber (EPDM 1, EPDM 2) to compose the composition according to the present invention complements the disadvantages and limitations of a single EPDM, frees cross-linking design, It is possible to satisfy the performance required by the engine mount.

In the present invention, the rubber composition should always be available at 140 ° C. or higher, and at the same time, the dynamic properties may be improved to lower the dynamic ratio, and at the same time, durability should be satisfied.

In this case, EPDM 1 does not contain oil, and EPDM 2 contains oil, and it is preferable that they are blended in a weight ratio of EPDM 1: EPDM 2 1: 3. For example, if 40g of EPDM 1 is selected, 120g of EPDM 2 is selected and blended with each other to constitute EPDM, which is a raw material rubber, which is a standard of other compounding components used in the present invention.

Here, the blending ratio of EPDM 1 and EPDM 2 is preferably maintained at 1: 3 by weight, and additives were added as follows with respect to 100 parts by weight of the EPDM raw material rubber thus blended.

At this time, the additive to be added is a term used in the field to which the present invention belongs, and refers to a crosslinking agent, an accelerator, a filler (reinforcement agent), a softener, an active agent, a vulcanizing aid, an anti-aging agent (an agent) and the like.

In addition, EPDM, which is vulcanized only with conventional sulfur, easily meets the required performance in terms of mechanical properties and fatigue performance, but it is difficult to meet the requirements of heat resistance and compression set. The material is heat resistant and the compression set satisfies the requirements, but not the mechanical properties and fatigue performance.

Therefore, to manufacture the anti-vibration rubber composition for the engine mount using a hybrid vulcanization system that can find the optimum point to satisfy all mechanical properties, fatigue performance, heat resistance, compression set, etc. There is a major feature of the present invention.

Therefore, in the hybrid crosslinking system, the vulcanization crosslinking system part according to the vulcanization method is monosulfide crosslink (monosulfide crosslink) because the heat resistance decreases when the polysulfide crosslnk (%) content is increased to improve the heat resistance of EPDM rubber. %) 0.4 to 1.5 parts by weight of sulfur was added to 100 parts by weight of the blended EPDM rubber in order to increase the content.In this case, to improve the fatigue performance, which is a disadvantage caused by the increase of the monosulfide crosslink (%) content. As an accelerator, CZ (N-Cyclohexyl-2-benzothiazyl-sulfenamide) and TT (Tetra methylthiuram disulfide) are adjusted to 0.5 to 3.5 parts by weight, respectively.

It should be limited to the above range because the accelerator content is less than 3.5 parts by weight, the scorch stability is poor and the workability is poor, and when the content is less than 0.5 parts by weight, the vulcanization time is too long and the productivity is lowered. When it is used in parts by weight, the durability of the rubber is lowered to satisfy the required level, and when it exceeds 1.5 parts by weight, it does not satisfy the heat resistance to the required use limit temperature.

As a peroxide crosslinking system, a rubber material crosslinked with a peroxide has a relatively simple crosslinking reaction, has high modulus, low permanent compression rate, and high heat resistance.

Common types of peroxides include DCP (Dicumyl peroxdie), DTBPH (2,5-dimethyl-2, 5-di-t-butyl peroxyhane) and TBPDB (Di-t-butyl peroxy di-siopropyl benzene). TBPDB, which has no high temperature vulcanization and blooming, and has excellent heat resistance, is used. If the content is less than 2 parts by weight, it is impossible to improve heat resistance and permanent compressibility due to the decrease in crosslinking density. Since it worsens the dust-proof performance, it should be limited to 2-8 parts by weight.

In addition, activated zinc may be used as a vulcanizing activator, which has a smaller particle size and a greater active effect than conventional zinc oxide, which may increase the crosslinking density, but when the content is less than 2 parts by weight, it causes a decrease in productivity. When it exceeds 7 parts by weight, it is appropriate to add 2 to 7 parts by weight since it inhibits scorch stability and causes a problem in workability.

In addition, a filler (= reinforcing agent) should be used in addition to the above-mentioned accelerator, and preferred fillers include carbon black, and these also have a low copper magnification and high attenuation since they have a large influence on the copper magnification and loss coefficient depending on the grade. The selection of the appropriate grade is very important.

Carbon black, which is used as a filler, is an important factor in determining the mechanical and dynamic properties of rubber and has different properties depending on particle diameter, structure, and surface activity.

In particular, in the case of carbon black, the smaller the structure and the larger the particle size, the smaller the magnification and tanδ, and the higher the magnification of the loss, the larger the magnification, regardless of the type and amount of carbon.

Therefore, in the present invention, it is possible to use SRF (Semi Reinforcing Furnace) having a low structure development, a large particle size, and FEF (Fast Extruding Furnace) having a small particle diameter and a developed structure to complement mechanical properties. The disadvantages of ratings can be overcome.

To this end, the SRF is 15 to 30 parts by weight, and the FEF should be added 10 to 20 parts by weight.

Further, a softener is further added. The softener is a paraffinic oil for improving heat resistance, and a high viscosity and low aromatic content is used, and 4-6 parts by weight is added to 100 parts by weight of the blended EPDM raw material rubber.

In addition, additives that may be added in the present invention include, for example, active agents, vulcanizing aids and preservatives (antiaging agents) and the like, which may be added as it is within the conventional content range.

For example, 1 to 3 parts by weight of stearic acid (Stearic acid) is preferable as the vulcanizing aid, if less than 1 part by weight, the crosslinking reaction is delayed, and when it is more than 3, the crosslinking reaction is accelerated, resulting in poor scorch stability.

In addition, SUN682 (product name as sunprax) is preferably 1 to 2 parts by weight, but when it is less than 1, ozone resistance is a problem, and when it is more than 2, an improvement in ozone resistance cannot be expected.

In addition, 13C (N-Phenyl-N'-isopropyl-p-phenylenediamine), 2,4 parts by weight is suitable as a defoaming agent. Difficult to do

In addition, the EPDM rubber composition of the present invention can be prepared according to a manufacturing method commonly used in this field, and can be prepared by, for example, a conventional mechanical kneading method.

Hereinafter, examples will be described.

In order to confirm the properties of the composition according to the present invention, specimens made of a rubber composition prepared as shown in Table 1 were prepared, and these were compared and analyzed.

At this time, the specimen is prepared by mixing carbon black, vulcanizing activator, vulcanizing aid, vulcanizing agent, and softener at the same time with EPDM using Banbury mixer for 3 minutes, mixing for 3 minutes to prepare final CMB (unvulcanized rubber). After the CMB was mixed with a vulcanizing agent and a promoter using a ROLL mixer.

The rubber composition thus prepared was measured using a rheometer (Rheometer, large diameter engineering) to measure the appropriate cure time, and then heated and pressurized to 160 kgf / cm 2 using a press to prepare a vulcanized specimen.

In addition, to evaluate the rubber specimens and products manufactured as described above, the following items were tested to evaluate the results.

-Hardness: measured with dumbbell type 3 according to KS M 6784

-Tensile strength and elongation: measured with dumbbell type 3 in accordance with KS M 6782

-Evaluation of aging properties: Record changes of properties after aging 1000 hours at 140 ℃

-Compression set: Change rate after 22 hours aging at 100 ℃ according to KS M 6518

-Evaluation of durability after aging: The engine mount is manufactured with composition to evaluate durability after 50 hours of aging at 120 ℃, 130 ℃ and 140 ℃.

In addition, the evaluation result was as Table 2.

As shown in Table 2, Example 3 to which a hybrid vulcanization system is applied is improved in comparison with those of Examples 1 and 2 as well as the existing natural rubber composition (conventional example) and a single EPDM composition (comparative example). It was confirmed that it exhibits heat resistance, durability, and a compression set.

In particular, as the SRF content increased compared to a single EPDM composition (comparative example), it was confirmed that the composition ratio of the composition was improved. Examples 1 to 3 applying the hybrid crosslinking system (hybrid vulcanization systme) showed heat resistance and permanent compression resistance ( It can be seen that the compression set is significantly improved.

Through this, it was possible to finally confirm that the mechanical properties and dynamic characteristics of the existing EPDM rubber can be complemented and can be applied as a high heat resistant engine mount.

Claims (3)

100 parts by weight of the EPDM blend blending EPDM 1 without oil and EPDM 2 with oil in a weight ratio of 1: 3;
Sulfur: 0.4-1.5 parts by weight,
CZ, TT: 0.5-3.5 parts by weight, respectively
Peroxide crosslinking agent: 2-8 parts by weight,
Semi Reinforcing Furnace (SRF): 15-30 parts by weight,
Fast Extruding Furnace (FEF): 10-20 parts by weight,
Paraffin oil: 4-6 parts by weight;
As other additives, activated zinc: 2-7 parts by weight, stearic acid: 1-3 parts by weight, SUN682 (sunprax): 1-2 parts by weight, 13C (N-Phenyl-N'-isopropyl-p-phenylenediamine): 2 Rubber composition for automobile engine mount applying a hybrid vulcanization system to EPDM, characterized in that -4 parts by weight is added.
The method of claim 1, further comprising:
The EPDM includes 4-6 wt% of ethylidene norbornene (ENB) and 50-70 wt% of ethylene, and a Mooney viscosity of 50-60 ml based on the total weight of EPDM, using a hybrid vulcanization system in EPDM. Rubber composition for automotive engine mount applied.
The method of claim 1, further comprising:
The peroxide crosslinking agent is TBPDB (Di-t-butyl peroxy di-siopropyl benzene) rubber composition for an automobile engine mount applying a hybrid vulcanization system to EPDM, characterized in that.