KR101646271B1 - 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

The present invention relates to a modified EPDM rubber and an EPDM rubber composition for an engine mount using the modified EPDM rubber. More particularly, the present invention relates to a modified EPDM rubber obtained by grafting polyethylene oxide or polystyrene to a maleic anhydride grafted EPDM rubber and an EPDM rubber composition using the modified EPDM rubber. The EPDM rubber composition of the present invention can be applied to an engine mount and the like because the EPDM rubber composition of the present invention has mechanical properties superior to those of a natural rubber material and exhibits excellent heat resistance which is difficult to realize in a natural rubber material.

Description

TECHNICAL FIELD [0001] The present invention relates to a modified EPDM rubber and an EPDM rubber composition for an engine mount using the modified EPDM rubber and an ethylene-propylene diene monomer (M-class)

The present invention relates to a modified EPDM rubber and an EPDM rubber composition for an engine mount using the same.

The engine mount of the vehicle serves to suppress the transmission of vibration generated in the engine. Therefore, it must be able to support heavy engines and have endurance performance against repeated fatigue. In addition, it is equipped in a high-temperature engine room, so it has a technical feature that heat resistance performance must be secured at the same time.

Conventional engine mount materials have been manufactured based on natural rubber having excellent mechanical properties. In the case of natural rubber, the normal use temperature is about 70 캜, but the technology has been developed so that it can be used at a temperature of about 100 캜. As shown in Korean Patent No. 10-0177580 and Korean Patent Laid-Open No. 10-2009-0056087, the improvement in heat resistance can be achieved by controlling the blending amount of natural rubber, sulfur and crosslinking accelerator, The focus of this study was on the study of the formulation system.

However, conventional engine mounts using natural rubber have a technical limitation that the use temperature does not exceed 100 캜. Recently, in order to improve the performance of the vehicle, the output of the engine has been rapidly increased, and the temperature of the engine room has rapidly risen. Further, the temperature of the engine room is further increased by adding various devices for the purpose of reducing the exhaust gas. As a result, a cost increase is caused by further mounting a heat plate to reduce the heat applied to the engine mount, and the problem of mount failure after long-term operation of the vehicle continues.

Accordingly, a technology for applying sulfur-crosslinked EPDM rubber (ethylene propylene diene monomer (M-class) rubber) having excellent heat resistance, weather resistance and ozone resistance as an engine mount material is disclosed in Korean Patent No. 10-087174, Patent No. 10-2004-0000852, etc. However, there is a problem in that the mechanical properties are lower than the natural rubber materials.

Accordingly, the present inventors have made efforts to solve the above problems, and as a result, they have found that a novel additive in which polyethylene oxide or polystyrene is grafted to an EPDM rubber grafted with maleic anhydride is synthesized and mixed with EPDM rubber, It is possible to produce an EPDM rubber composition capable of reducing the deterioration of physical properties due to aging even at a high temperature of about 140 ° C. while exhibiting mechanical strength. Thus, the present invention has been completed.

Accordingly, an object of the present invention is to provide an EPDM rubber composition excellent in 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 a maleic anhydride grafted EPDM rubber.

Further, the present invention relates to a rubber composition comprising 100 parts by weight of an EPDM rubber,

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

0.5 to 3.0 parts by weight of a crosslinking agent; And

0.2 to 5.0 parts by weight of a crosslinking accelerator;

And an EPDM rubber composition.

The EPDM rubber composition according to the present invention contains an additive which is obtained by grafting polyethylene oxide or polystyrene to a maleic anhydride-grafted EPDM rubber, thereby securing mechanical properties equal to or more than that of a natural rubber material and exhibiting excellent heat resistance Therefore, it can be effectively applied to an engine mount or the like.

Hereinafter, the present invention will be described in detail.

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

The maleic anhydride grafted EPDM rubber is grafted with maleic anhydride on an EPDM rubber having 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. The maleic anhydride grafted EPDM rubber preferably has a maleic anhydride content of 0.1 to 2.0% by weight and a Mooney viscosity (ML 1 + 4 125 ° C) of 25 to 35. If the content of maleic anhydride is less than 0.1% by weight, the graft reaction of polyethylene oxide or polystyrene may not be smoothly performed. If the content of maleic anhydride exceeds 2.0% by weight, the elasticity of EPDM itself may be deteriorated. If the Mooney viscosity is less than 25, the mechanical strength of the EPDM rubber composition may be deteriorated. If the Mooney viscosity is more than 35, the workability may be deteriorated. Specifically, Royaltuf 498 manufactured by Chemtura may be used.

The polyethylene oxide preferably has an amine group at the end of its main chain and preferably has a molecular weight of 1,000 to 10,000. If the molecular weight is too small, the effect of increasing the mechanical strength of the EPDM rubber composition due to the graft may not be obtained. If the molecular weight is too large, the concentration of the terminal functional group may become too low. The modified EPDM rubber of the present invention can be produced by grafting polyethylene oxide onto an anhydrous maleic acid grafted EPDM rubber by imidization reaction of maleic anhydride with an amine group of polyethylene oxide and an EPDM rubber as shown in Reaction Scheme 1 below. In the imidization reaction, the weight ratio of polyethylene oxide to maleic anhydride-modified EPDM rubber is preferably 5/95 to 50/50. If the amount of polyethylene oxide is too large, there may be a problem of property change. If too small, It is preferable to select the weight ratio of the above range.

[Reaction Scheme 1]

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

It is preferable to use the polystyrene represented by the formula (1) obtained by the polymerization reaction of dibenzyltithiocarbonate and styrene monomer. If the molecular weight is too small, the effect of increasing the mechanical strength of the rubber composition due to the graft may not be obtained. If the molecular weight is too large, the concentration of the functional group becomes too low .

[Chemical Formula 1]

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

The polystyrene is grafted onto a maleic anhydride-grafted EPDM rubber by grafting-onto reaction. Specifically, as shown in Reaction Scheme 2, the weight ratio of the maleic anhydride-grafted EPDM rubber to the polystyrene is preferably 95/5 to 50/50. If the amount of polystyrene used is too large, there may be a problem that the physical properties may change. On the other hand, if the amount is too small, there is a problem that the reaction does not occur.

[Reaction Scheme 2]

In the above Reaction Scheme 2, a and b are an integer of 5 to 50.

The present 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. Since the EPDM rubber does not have a double bond in the main chain, the ethylidene norbornene component, which is a diene component, can not be vulcanized by itself. The EPDM rubber can control various properties and processability depending on the polymerization ratio of ethylene and propylene and the content of ethylidene norbornene. In the present invention, the EPDM rubber has a Mooney viscosity (ML 1 + 4 125 ° C) of 25 to 35, an ethylidene norbornene content of 6 to 9% by weight, an ethylene content of 50 to 70% 44% by weight is preferably used. When the content of ethylidene norbornene is less than 6% by weight, reaction sites for rubber vulcanization are few and reaction effects for obtaining desired mechanical properties are not expected. When the content is more than 9% by weight, the viscosity of the starting rubber increases, . If the content of ethylene is too low or the content of propylene is too high, the orientation in the molecular structure may be difficult and mechanical properties may be deteriorated. If the ethylene content is too high or the propylene content is too low, There may be a problem that performance is deteriorated. As a specific example of such EPDM rubber, Keltan 7441 of DSM can be used.

As the modified EPDM rubber component, the modified EPDM rubber obtained by grafting polyethylene oxide or polystyrene to the maleic anhydride-modified EPDM rubber of the present invention is used, and the amount of the modified EPDM rubber used is 3 to 10 parts by weight based on 100 parts by weight of the EPDM rubber It is good. If the amount of the modified EPDM rubber is less than 3 parts by weight, the effect of increasing the tensile strength of the composition upon addition is insignificant. If the amount of the modified EPDM rubber is more than 10 parts by weight, the crosslinking density of the composition excessively increases.

The crosslinking agent and the crosslinking accelerator are added to the EPDM rubber in order to perform crosslinking by sulfur. As the crosslinking agent, sulfur is preferably used, and the amount of the crosslinking agent is preferably 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 durability deterioration. When the amount is more than 3.0 parts by weight, It is difficult to express. As the crosslinking accelerator, N-cyclohexyl-2-benzothiazyl-sulfenamide, tetramethylthiuram disulfide or a mixture thereof may be used, and the amount thereof is preferably 0.2 to 5.0 parts by weight. If the amount of the crosslinking accelerator is less than 0.2 parts by weight, the vulcanization rate may be lowered and the production efficiency may be lowered. If the amount of the crosslinking accelerator is more than 5.0 parts by weight, the vulcanization rate may become too high.

The EPDM rubber composition of the present invention may further contain additives commonly used in addition to the above-mentioned constituent materials, for example, active agents, vulcanization auxiliary agents, fillers and the like. As the activator, zinc oxide, zinc carbonate, magnesium oxide and the like can be used. As the vulcanization aid, stearic acid, oleic acid, lauric acid and the like can be used. The filler is not particularly limited, but carbon black is preferably used.

The EPDM rubber composition of the present invention can be applied to an engine mount and the like because the EPDM rubber composition of the present invention has mechanical properties superior to those of a natural rubber material and exhibits excellent heat resistance which is difficult to realize in a natural rubber material.

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-grafted 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) And the mixture was reacted at 120 DEG C for 1 hour while stirring at 20 rpm. After the acetone was reprecipitated, the unreacted polyethylene oxide in which the terminal of the main chain was substituted with an amine group was extracted, and the modified EPDM rubber obtained by grafting polyethylene oxide onto the maleic anhydride-grafted EPDM rubber was recovered. GPC, NMR and IR analysis showed that the recovered EPDM rubber had a molecular weight of at least 100,000 g / mol and at least 2.5 polyethylene oxide groups branched on the EPDM rubber chain.

Example 2

1.5 g of dibenzyltithiocarbonate, 100 g of styrene monomer and 0.96 g of azobisisobutyronitrile (AIBN) as a reaction initiator were placed in a 200 mL Schlenk flask. The functionalized polystyrene represented by the above formula (1) was prepared by reacting at 60 ° C for 10 hours using an oil bath in which the temperature of the reactor was maintained in a nitrogen atmosphere.

1 g (8.0 x 10 ^-6 mol) of the prepared polystyrene, 1.85 x 10 ^-3 mol of EPDM rubber (Chemtura, Royaltuf 498) and 0.05 g (1.85 x 10 ^-3 mol) of dicumyl peroxide were dissolved in a solvent Was dissolved in 40 ml of xylene in a Schlenk flask while stirring. The reaction was carried out at 138 DEG C for 4 hours at 350 rpm. The unreacted polystyrene was extracted with acetone, dissolved in tetrahydrofuran (THF) solution, and acetone was precipitated again to obtain a maleic anhydride-grafted EPDM A modified EPDM rubber grafted with polystyrene to rubber was recovered. NMR and IR analysis showed that the content of polystyrene grafted to the EPDM rubber was 7% by weight and that of the polystyrene branched on the EPDM rubber chain was 3 or more.

Example 3

The EPDM rubber and the modified EPDM rubber prepared in Example 1 were put into a Banbury mixer, and after the Soviet Union for 2 minutes, a crosslinking agent, a crosslinking accelerator, an activator and a vulcanizing auxiliary were added and kneaded, followed by dispersion and mixing using a roll mixer. Specific constituent materials and amounts used are shown in Table 1 below.

Example 4

The EPDM rubber and the modified EPDM rubber prepared in Example 2 were put into a Banbury mixer, and after 2 minutes of Soviet Union, carbon black was added and kneaded for 2 minutes. Then, a crosslinking agent, a crosslinking accelerator, an activator and a vulcanization auxiliary agent were added and kneaded, followed by dispersion and mixing using a roll mixer. Specific constituent materials and amounts used are shown in Table 1 below.

Comparative Example 1

A rubber composition was prepared in the same manner as in Example 4 except that the modified EPDM rubber was not used. Specific constituent materials and amounts used are shown in Table 1 below.

Comparative Example 2

The natural rubber was kneaded for 2 minutes using a Banbury mixer after the Soviet Union and carbon black was added for 2 minutes. Then, a crosslinking agent, a crosslinking accelerator, an activator, a vulcanization auxiliary agent and an antioxidant were added and kneaded, followed by dispersion and mixing using a roll mixer. Specific constituent materials and amounts used are shown in Table 1 below.

division Content (parts by weight) Example 3 Example 4 Comparative Example 1 Comparative Example 2 Raw rubber Natural rubber - - - 100 EPDM rubber 100 100 100 - Modified EPDM rubber Polyethylene oxide
Graft - 7 - - Polystyrene graft 7 - - - Cross-linking 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 Activator Zinc oxide 2.5 2.5 2.5 2.5 Vulcanization auxiliary Stearic acid 2 2 2 2 Filler Carbon black - 40 40 40 Antioxidant RD - - - 1.5 3C - - - One Natural rubber: [SMR CV60]
EPDM rubber: [Keltan 7441, DSM]
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

Property measurement test

The rubber compositions prepared in Examples 3 and 4 and Comparative Examples 1 and 2 were measured by using a Rheometer (Monsanto R100) for optimum flow time and then heated and pressed at 165 ° C at 210 kgf / cm ² using a press, And the following items were tested. The results are shown in Table 2 below.

- Tensile strength and elongation: Measured with dumbbell type 3 according to KS M 6782.

- Flexural Cracking Test: The occurrence of flex cracking and the growth rate were evaluated according to KS M 6791. However, the growth rate was measured the number of times when the crack reached 5 mm.

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

- Durability performance evaluation after aging: An engine mount was manufactured with the compositions of Examples 3 and 4 and Comparative Examples 1 and 2, and the durability performance after aging at 140 ° C for 500 hours 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 (cycle) 4300 4500 3000 5000 After aging
Rate of change (%) The tensile strength -16 -15 -17 -85 Elongation -18 -13 -15 -65 product Durability performance (cycle) 400000 450000 350000 20000

As shown in Table 2, it can be seen that Comparative Example 1 using EPDM rubber alone had a somewhat lower tensile strength than Comparative Example 2 using natural rubber. In Example 1 where the modified EPDM rubber of the present invention was mixed And 2, the tensile strength increase effect is about 7 to 16% as compared with Comparative Example 1. [ This can be explained by the fact that the number of possible crosslinking reactions increased by adding the modified EPDM rubber of the present invention. That is, the mechanical properties are improved by increasing the cross-link density, and thus the fatigue performance is simultaneously improved. In addition, it can be seen that the change in physical properties at a high temperature of 140 ° C, which is difficult to cope with the conventional natural rubber material, is within 20%. As a result, it was confirmed that it is possible to compensate the mechanical properties, which is a disadvantage of the conventional EPDM rubber, and to apply it as a high heat resistant engine mount.

Claims (7)

A maleic anhydride grafted EPDM rubber, a modified EPDM rubber grafted with polyethylene oxide or polystyrene,
The maleic anhydride grafted EPDM rubber is grafted with 0.1 to 2.0% by weight of maleic anhydride in an EPDM rubber having 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 However,
Wherein the maleic anhydride grafted EPDM rubber has a Mooney viscosity (ML 1 + 4 125 ° C) of 25 to 35.
delete The modified EPDM rubber according to claim 1, wherein the modified EPDM rubber is prepared by imidizing maleic anhydride of maleic anhydride-grafted EPDM rubber and amine groups at the main chain ends 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 produced by reacting a maleic anhydride-grafted EPDM rubber with polystyrene having a molecular weight of 1,000 to 10,000,
[Chemical Formula 1]

In Formula 1, a and b are an integer of 5 to 50.
With respect to 100 parts by weight of EPDM rubber,
3 to 10 parts by weight of the modified EPDM rubber of any one of claims 1, 3 and 4;
0.5 to 3.0 parts by weight of a crosslinking agent; And
0.2 to 5.0 parts by weight of a crosslinking accelerator;
≪ / RTI >
6. The process of claim 5, wherein the EPDM rubber has an ethylidene norbornene content of 6 to 9 wt%, an ethylene content of 50 to 70 wt%, a propylene content of 21 to 44 wt%, a Mooney viscosity (ML 1 + 4 125 Lt; 0 > C) is 25 to 35.
6. The EPDM rubber composition according to claim 5, wherein the EPDM rubber composition further comprises an activator and a vulcanization aid.