KR20120000258A - Modified ethylene propylene diene monomer (m-class) rubber and ethylene propylene diene monomer (m-class) rubber composition for engine mount using the same - Google Patents

Abstract

PURPOSE: An ethylene propylene diene monomer(M-class) rubber composition is provided to have excellent physical properties and excellent heat resistance which can not be obtained from natural rubber materials, thereby useful for engine mounts, etc. CONSTITUTION: A modified ethylene propylene diene monomer(M-class) rubber is grafted of a polyethylene oxide or polystyrene into a maleic anhydride-graft EPDM rubber. The content of maleic anhydride in maleic anhydride-graft EPDM rubber is 0.1-2.0wt%, and the mooney viscosity(ML 1+4 125°C) thereof is 25-35. An ethylene propylene diene monomer rubber composition comprises 3-10 parts by weight of reformed EPDM rubber, 0.5-3.0 parts by weight of cross-linking agent and 0.2-5.0 parts by weight of crosslinking promoter on the basis of 100 parts by weight of EPDM rubber.

Description

Modified ethylene propylene diene monomer (M-class) rubber and Ethylene propylene diene monomer (M-class) rubber composition for engine mount using the same}

The present invention relates to modified EPDM rubber and EPDM rubber compositions for engine mounting using the same.

The engine mount of the vehicle serves to suppress transmission of vibration generated from the engine. Therefore, it must be able to support heavy engines and be durable against repeated fatigue. In addition, since it is mounted in a high temperature engine room, it has a technical feature to ensure heat resistance at the same time.

Conventional engine mount materials have been produced based primarily on natural rubber with excellent mechanical properties. In the case of natural rubber, the normal use temperature is about 70 ℃, but the technology has been developed to be able to use even at a temperature of about 100 ℃ by improving this. The improvement of heat resistance is controlled by the combination of the natural rubber, sulfur and crosslinking accelerators as shown in the Republic of Korea Patent Registration No. 10-0177580, Republic of Korea Patent Publication No. 10-2009-0056087, etc. The focus was on the formulation system study.

However, the engine mount using a conventional natural rubber has a technical limitation that the use temperature is difficult to exceed 100 ℃. Recently, the output of the engine has been rapidly accelerated for the purpose of improving the performance of the vehicle. As a result, the temperature of the engine room is also rapidly increased, and thus, the temperature usually exceeds 130 ° C. In addition, the temperature of the engine room is further increased with the addition of various devices for the purpose of reducing the exhaust gas. Accordingly, a further increase in cost occurs by additionally mounting a heat shield plate to reduce heat loaded on the engine mount, and a problem of mounting damage after long-term driving of the vehicle continues.

Accordingly, a technology for applying ethylene propylene diene monomer (M-class) rubber (EPDM rubber) having excellent heat resistance, weather resistance and ozone resistance to sulfur crosslinking and applying it as a material for engine mounting is disclosed in Korean Patent No. 10-087174, Republic of Korea Patent No. 10-2004-0000852 et al., But the mechanical properties were lower than the natural rubber material.

Accordingly, the present inventors have attempted to solve the above problems, synthesized a novel additive grafted polyethylene oxide or polystyrene to the maleic anhydride-grafted EPDM rubber, and when mixed with the EPDM rubber and sulfur crosslinked, equivalent to more than natural rubber The present invention has been found to be possible to prepare a rubber composition of EPDM material that can reduce the physical property degradation caused by aging even at a high temperature of about 140 ℃ while showing mechanical strength.

Therefore, an object of the present invention is to provide an EPDM rubber composition having excellent mechanical properties such as tensile strength and heat aging resistance.

The present invention is characterized by a modified EPDM rubber obtained by grafting polyethylene oxide or polystyrene to maleic anhydride graft EPDM rubber.

In addition, the present invention with respect to 100 parts by weight of EPDM rubber,

3 to 10 parts by weight of the modified EPDM rubber;

0.5 to 3.0 parts by weight of crosslinking agent; And

0.2 to 5.0 parts by weight of crosslinking accelerator;

An EPDM rubber composition comprising a.

The EPDM rubber composition according to the present invention includes an additive obtained by grafting polyethylene oxide or polystyrene to maleic anhydride graft EPDM rubber, thereby securing excellent mechanical properties equivalent to those of natural rubber materials and exhibiting excellent heat resistance that is difficult to be realized in natural rubber materials. Therefore, it can be usefully applied to the engine mount.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a modified EPDM rubber obtained by grafting polyethylene oxide or polystyrene to maleic anhydride graft EPDM rubber.

The maleic anhydride graft EPDM rubber is preferably 0.1 to 2.0% by weight of grafted maleic anhydride and a Mooney viscosity (ML 1 + 4 125 ° C.) of 25 to 35. When the content of maleic anhydride is less than 0.1% by weight, the graft reaction of polyethylene oxide or polystyrene may not occur smoothly, and when the content of maleic anhydride exceeds 2.0% by weight, there may be a problem of inhibiting the elasticity of EPDM itself. In addition, when the Mooney viscosity is less than 25, there may be a problem of lowering the mechanical strength of the EPDM rubber composition, and when the Mooney viscosity exceeds 35, workability may be deteriorated. Specifically, Royaltuf 498 by Chemtura may be used.

The polyethylene oxide is used to have an amine group at the end of the main chain, it is preferable to use a molecular weight of 1,000 ~ 10,000. If the molecular weight is too small it may not be possible to obtain a sufficient mechanical strength synergistic effect of the EPDM rubber composition according to the graft, if too large may have a problem that the concentration of the terminal functional group is too low. The modified EPDM rubber of the present invention can be prepared by grafting polyethylene oxide to maleic anhydride graft EPDM rubber by imidization reaction of amine of polyethylene oxide with maleic anhydride of EPDM rubber as shown in Scheme 1 below. In the imidization reaction, the weight ratio of polyethylene oxide and maleic anhydride graft EPDM rubber is preferably 5/95 to 50/50. If the amount of polyethylene oxide is used too much, there may be a problem of change in physical properties. Since it may not occur, it is better to select the weight ratio in the above range.

Scheme 1

In Scheme 1, y is an integer of 25 to 250.

It is preferable to use what is represented by General formula (1) obtained by polymerizing a dibenzyl trithiocarbonate and a styrene monomer as said polystyrene. It is preferable to use a polystyrene having a molecular weight of 1,000 to 10,000, if the molecular weight is too small may not obtain a mechanical strength synergistic effect of the rubber composition according to the graft, if the molecular weight is too large, the concentration of the functional group is too low There can be.

[Formula 1]

In Formula 1, a and b are integers of 5 to 50.

The polystyrene is grafted to maleic anhydride graft EPDM rubber by a grafting-onto reaction. Specifically, as shown in Scheme 2 below, the weight ratio of maleic anhydride graft EPDM rubber and the polystyrene is preferably 95/5 to 50/50. If the amount of polystyrene is too large, there may be a problem that a change in physical properties may occur. On the contrary, if the amount of polystyrene is too small, there may be a problem that no reaction occurs.

Scheme 2

In Scheme 2, a and b are integers of 5 to 50.

The invention also relates to an EPDM rubber composition comprising an EPDM rubber, the modified EPDM rubber, a crosslinking agent and a crosslinking accelerator.

The EPDM rubber is used as a matrix resin of the composition, and since there is no double bond in the main chain, it does not form a vulcanized structure on its own and the ethylidene norbornene component, which is a diene component, is introduced. EPDM rubber can be controlled in various ways depending on the polymerization ratio of ethylene and propylene and the content of ethylidene norbornene. In the present invention, it is preferable to use an ethylidene norbornene content of 6 to 9% by weight, an ethylene content of 50 to 70% by weight and a propylene content of 21 to 44% by weight. When the ethylidene norbornene content is less than 6% by weight, there are few reaction sites for rubber vulcanization, so it is difficult to expect the effect of vaporization to obtain the desired mechanical properties. When the content of the ethylidene norbornene is higher than 9% by weight, the workability of the raw material rubber becomes high, resulting in poor processability. There can be. In addition, if the content of ethylene is too small or the content of propylene is too high, the orientation in the molecular structure is difficult, which may cause a problem of mechanical properties deterioration. If the content of ethylene is too high or the content of propylene is too low, dynamic at low temperatures may occur. There may be a problem of poor performance. As a specific example of such EPDM rubber, Keltan 7441 of DSM, etc. can be used.

The modified EPDM rubber component uses a modified EPDM rubber obtained by grafting polyethylene oxide or polystyrene to the maleic anhydride graft EPDM rubber described above. The amount of the modified EPDM rubber is used in an amount of 3 to 10 parts by weight based on 100 parts by weight of EPDM rubber, which is a matrix resin. It is good. When the amount of the modified EPDM rubber is less than 3 parts by weight, the effect of increasing the tensile strength of the composition according to the addition is insignificant, and when used in excess of 10 parts by weight, the crosslinking density of the composition may be excessively increased to reduce elasticity.

The crosslinking agent and the crosslinking accelerator are added to the EPDM rubber to effect crosslinking with sulfur. Sulfur is used as the crosslinking agent, and the amount is preferably added in an amount of 0.5 to 3.0 parts by weight. If the amount is less than 0.5 parts by weight, there may be a problem of deterioration in durability. Difficult to express In addition, the cross-linking accelerator may be used N-cyclohexyl-2-benzothiazyl-sulfenamide, tetra methyl thiuram disulfide or a mixture thereof and the amount is preferably 0.2 to 5.0 parts by weight. If the amount of the cross-linking accelerator is less than 0.2 parts by weight, the vulcanization rate may be lowered, resulting in decreased production efficiency.

The EPDM rubber composition of the present invention may further include additives commonly used in addition to the constituent materials, for example, active agents, vulcanization aids, fillers, and the like. As the active agent, zinc oxide, zinc carbonate, magnesium oxide, or the like may be used, and as a vulcanizing aid, stearic acid, oleic acid, lauric acid, or the like may be used. In addition, the filler is not particularly limited, but preferably carbon black is used.

The EPDM rubber composition of the present invention has excellent mechanical properties equivalent to those of natural rubber materials and at the same time exhibits excellent heat resistance that is difficult to realize in natural rubber materials, and thus can be usefully applied to engine mounts and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

[Example]

Example 1

250 g of maleic anhydride graft EPDM rubber (Chemtura, Royaltuf 498) and 25 g of polyethylene oxide (Huntsman Co., Jeffamine M-2070, number average molecular weight 2000, polydispersity index 1.20) substituted with an amine group at the end of the main chain The mixture was added to a mixer and reacted with stirring at 20 rpm for 1 hour at 120 ° C. After re-precipitating in acetone, the unreacted main chain terminal was extracted with polyethylene oxide substituted with an amine group to recover a modified EPDM rubber grafted polyethylene oxide to maleic anhydride graft EPDM rubber. GPC, NMR and IR analysis showed that the recovered EPDM rubber had a molecular weight of more than 100,000 g / mol and more than 2.5 polyethylene oxide branched to the EPDM rubber chain.

Example 2

1.5 g of dibenzyl trithiocarbonate, 100 g of styrene monomer and 0.96 g of asobisisobutylonitrile (AIBN) as a reaction initiator were charged to a 200 mL Schlenk flask. The functionalized polystyrene represented by Chemical Formula 1 was prepared by reacting the reactor for 10 hours at 60 ° C. using an oil bath having a temperature control while maintaining the reactor in a nitrogen atmosphere.

0.96 g (1.85 x 10 ^-3 mol) of polystyrene, 1 g (8.0 x 10 ^-6 mol) of EPDM rubber (Chemtura, Royaltuf 498) and 0.05 g (1.85 x 10 ^-3 mol) of dicumyl peroxide 40 mL of in xylene was placed in a Schlenk flask and dissolved with stirring. The reaction was carried out while stirring the mixture at 350 rpm for 4 hours at 138 ° C., and then unreacted polystyrene was extracted with acetone, dissolved in tetrahydrofuran (THF) solution, and acetone precipitated again to give maleic anhydride graft EPDM. The modified EPDM rubber in which the polystyrene was grafted to the rubber was recovered. NMR and IR analysis showed that the content of polystyrene grafted to the EPDM rubber was 7% by weight, and at least 3 polystyrene branched to the EPDM rubber chain.

Example 3

The EPDM rubber and the modified EPDM rubber prepared in Example 1 were added to a Banbury mixer, and after 2 minutes of sowing, a crosslinking agent, a crosslinking accelerator, an activator and a vulcanizing aid were added and kneaded, and then dispersed and mixed using a roll mixer. Specific components and amounts used are shown in Table 1 below.

Example 4

The EPDM rubber and the modified EPDM rubber prepared in Example 2 were added to a Banbury mixer and soaked for 2 minutes, followed by carbon black and kneaded for 2 minutes. Thereafter, a crosslinking agent, a crosslinking accelerator, an activator and a vulcanization aid were added and kneaded, and then dispersed and mixed by using a roll mixer. Specific components and amounts used are shown in Table 1 below.

Comparative Example 1

In the same manner as in Example 4, but the rubber composition was formulated without using a modified EPDM rubber. Specific components and amounts used are shown in Table 1 below.

Comparative Example 2

The natural rubber was kneaded for 2 minutes using carbon black and then mixed for 2 minutes using a Banbury mixer. Thereafter, a crosslinking agent, a crosslinking accelerator, an activator, a vulcanizing aid and an anti-aging agent were added and kneaded, and then dispersed and mixed by using a roll mixer. Specific components and amounts used are shown in Table 1 below.

division Content (part by weight) Example 3 Example 4 Comparative Example 1 Comparative Example 2 Raw material rubber Natural rubber - - - 100 EPDM rubber 100 100 100 - Modified EPDM rubber Polyethylene oxide
Graft - 7 - - Polystyrene graft 7 - - - Crosslinking agent sulfur 0.5 2 0.5 0.75 Crosslinking accelerator CZ One 1.2 One 1.2 TT 2 0.3 2 0.3 Active agent Zinc oxide 2.5 2.5 2.5 2.5 Vulcanization Stearic acid 2 2 2 2 Filler Carbon black - 40 40 40 Anti-aging RD - - - 1.5 3C - - - One Natural Rubber: [SMR CV60]
EPDM Rubber: [Keltan 7441, DSM Corporation]
CZ: N-cyclohexyl-2-benzothiazyl-sulfenamide
TT: Tetra methylthiuramdisulfide
Carbon Black: Semi-Reinforced Furnace Black
RD: Polymerized 2,2,4-trimethyl-1,2 dihydroquinoline
3C: N-Phenyl-N'-isopropyl-p-phenylenediamine

Physical property test

The rubber compositions prepared in Examples 3 and 4 and Comparative Examples 1 and 2 were vulcanized by measuring the proper vulcanization time using a rheometer (Monsanto R100) and heating and pressing them at 210 kgf / cm ² at 165 ° C. using a press. To prepare and to test for the following items and the results are shown in Table 2 below.

-Tensile strength and elongation: measured by dumbbell No. 3 in accordance with KS M 6782.

Flexural Crack Test: The incidence and growth rate of flexural cracks were evaluated according to KS M 6791. However, the growth rate was measured the number of times when the crack reaches 5 mm.

-Evaluation of aging properties: Changes in physical properties were recorded after aging at 140 ° C. for 1,000 hours.

-Evaluation of durability after aging: Engine mounts were prepared by the compositions of Examples 3 and 4 and Comparative Examples 1 and 2, and durability after 500 hours of aging at 140 ° C. was evaluated.

division Evaluation results Example 3 Example 4 Comparative Example 1 Comparative Example 2 Psalter Tensile strength (kgf / cm ² ) 225 245 210 230 % Elongation 760 768 780 630 Fatigue Performance 4300 4500 3000 5000 After aging
% Change The tensile strength -16 -15 -17 -85 Elongation -18 -13 -15 -65 product Durability cycle 400000 450000 350000 20000

As shown in Table 2, Comparative Example 1 using only EPDM rubber can be seen that the tensile strength is slightly lower than Comparative Example 2 using natural rubber, Example 1 mixed with modified EPDM rubber of the present invention In case of 2, it can be seen that the tensile strength is increased by about 7 to 16% compared to Comparative Example 1. This can be explained by the increase in the number of possible crosslinking reactions by adding the modified EPDM rubber of the present invention. In other words, as the crosslinking density was increased, the mechanical properties were improved, and accordingly fatigue performance was also improved. In addition, it can be seen that the change in physical properties at a high temperature of 140 ° C., which was difficult to cope with existing natural rubber materials, is within 20%. As a result, it was confirmed that the mechanical properties, which are disadvantages of the existing EPDM rubber, can be compensated and applied as a high heat resistant engine mount.

Claims (7)

Modified EPDM rubber obtained by grafting polyethylene oxide or polystyrene to maleic anhydride graft EPDM rubber.
The modified EPDM rubber according to claim 1, wherein the maleic anhydride graft EPDM rubber has a content of grafted maleic anhydride of 0.1 to 2.0 wt% and a Mooney viscosity (ML 1 + 4 125 ° C) of 25 to 35. .
The modified EPDM rubber according to claim 1, wherein the modified EPDM rubber is prepared by imidization of maleic anhydride of maleic anhydride graft EPDM rubber with an amine group at the main chain terminal of polyethylene oxide having a molecular weight of 1,000 to 10,000. Rubber.
The modified EPDM rubber according to claim 1, wherein the modified EPDM rubber is prepared by the reaction of maleic anhydride graft EPDM rubber with polystyrene represented by the following Chemical Formula 1 having a molecular weight of 1,000 to 10,000:
[Formula 1]

In Formula 1, a and b are integers of 5 to 50.
Per 100 parts by weight of EPDM rubber,
3 to 10 parts by weight of the modified EPDM rubber of any one of claims 1 to 4;
0.5 to 3.0 parts by weight of crosslinking agent; And
0.2 to 5.0 parts by weight of crosslinking accelerator;
EPDM rubber composition comprising a.
6. The EPDM rubber composition according to claim 5, wherein the EPDM rubber has an ethylidene norbornene content of 6 to 9% by weight, an ethylene content of 50 to 70% by weight and a propylene content of 21 to 44% by weight.
6. The EPDM rubber composition according to claim 5, wherein the EPDM rubber composition further comprises an active agent and a vulcanizing aid.