KR20120019272A - Ethylene propylene diene monomer (m-class) rubber composition for air intake hose - Google Patents

Abstract

PURPOSE: An EPDM rubber composition is provided to have excellent oil resistance, negative pressure resistance, vibration resistance, etc, thereby not discharging harmful hydrochloric acid, etc. CONSTITUTION: An EPDM rubber composition comprises 200-250 parts by weight of carbon black, 0,3-0.8 parts by weight of sulfur, and as a vulcanization accelerator, 0.5-1 parts by weight of dipentamethylenethiuram tetrasulfide, 0.5-1 parts by weight of zinc di-n-butyldithiocarbamate, 0.5-1 parts by weight of tetramethyl-thiuram disulfide and 1.5-2.5 parts by weight of 2-mercaptobenzothiazole, and as a plasticizer 50-60 parts by weight of a paraffin oil and 50-60 parts by weight of ester oil, and as an antioxidant, 1-2.5 parts by weight of α-dimethylbenzyl-diphenylamine 1-2.5 parts by weight of 2-mercaptobenzoimidazole and 1-2.5 parts by weight of trimethyl dihydroquinoline polymer, on the basis of 175 parts by weight of EPDM rubber containing oil.

Description

EPDM rubber composition for automobile air intake hose {Ethylene propylene diene Monomer (M-class) rubber composition for Air intake hose}

The present invention relates to an EPDM rubber composition for automobile air intake hose, the EPDM rubber composition of the present invention exhibits excellent physical properties in terms of oil resistance, pressure resistance and vibration resistance.

In general, various methods have been developed to secure durability of the air intake hose rubber mounted on the intake system of an automobile.

Currently, air intake hose rubber materials for automobiles are made of materials having good oil resistance such as epichlorohydrin rubber, chlorinated polyethylene rubber, and thermoplastic elastomer. . However, epichlorohydrin rubber is expensive in terms of material cost, and chlorinated polyethylene rubber is not used in overseas automobile manufacturers due to the bad working environment at the factory due to the generation of chlorine gas which is harmful to workers in the molding process.

On the other hand, in the case of general general EPDM rubber materials applied to automotive cooling hoses and weather strips, EPDM rubber has a low molecular weight (Mw) of about 200,000, a wide molecular weight distribution, and the content of EPDM rubber when vulcanized. It is composed of about 30 to 50% by weight in the composition, and the content of carbon black is about 15 to 20% by weight. However, the rubber composition vulcanized in this way is difficult to satisfy the oil resistance performance required by the air inlet hose. This is because EPDM rubber vulcanizates themselves are mineral oil-based fluids and synthetic hydrocarbon lubricants, and polymers that are not resistant to petroleum fuels. When the air inlet hose formed by the composition of the existing EPDM rubber composition is mounted on a vehicle, the vehicle is driven by blow-by gas, especially engine oil and fuel oil mixture oil, which flows through the breather hose and the cylinder head cover. As a result, the air inlet hose swells before the desired driving distance, causing cracks. This phenomenon of swelling can be reproduced in the laboratory, and the evaluation to confirm the oil resistance performance of the compounded rubber can be confirmed by changing the physical properties by immersing the test specimen in No. 3 oil specified in ASTM, and general general EPDM rubber 110 to 130%, accompanied by a decrease in hardness, tensile strength and elongation. In order to improve oil resistance performance, high-charging formulations filled with 40% by weight or more of carbon black in the entire rubber composition should be carried out. Finding the rubber is very important. Since high molecular weight raw material rubber is used, excellent physical properties and carbon black filling rate can be increased. However, the raw material rubber having a high molecular weight has a problem of poor mixing workability.

Accordingly, the present inventors have tried to solve the problems described above, using a high molecular weight EPDM rubber containing oil as the raw material rubber, the specific ratio of the inorganic filler, vulcanization accelerator, plasticizer, anti-aging agent with sulfur The present invention has been completed by knowing that it is possible to prepare a new EPDM material that can prevent cracking and damage due to swelling while satisfying the mechanical properties of the air inlet hose by adding and crosslinking. That is, an object of the present invention is to provide a rubber composition for automobile air intake hoses with improved oil resistance.

The present invention

Per 175 parts by weight of oil-containing EPDM rubber

200 to 250 parts by weight of carbon black;

Sulfur 0.3 to 0.8 parts by weight;

0.5-1 weight part of dipentamethylenethiuram tetrasulfide, a vulcanization accelerator, 0.5-1 weight part of zinc di-n-butyldithiocarbamate, 0.5-1 weight part of tetramethyl-thiuram disulfide and 2-mercaptobenzothia Sol 1.5 to 2.5 parts by weight;

50 to 60 parts by weight of a plasticizer paraffin oil and 50 to 60 parts by weight of ester oil; And

1 to 2.5 parts by weight of an anti-aging agent α-dimethylbenzyl-diphenylamine, 1 to 2.5 parts by weight of 2-mercaptobenzoimidazole and 1 to 2.5 parts by weight of trimethyl dihydroquinoline polymer;

An EPDM rubber composition comprising a.

The EPDM rubber composition according to the present invention has low manufacturing cost by using EPDM rubber which is a general purpose rubber as a raw material rubber, and does not emit harmful chlorine gas to workers, thereby improving the working environment, and having oil resistance, pressure resistance and vibration resistance. Since it is excellent, it can be usefully applied as a hose for automobile air intake.

The present invention uses a high molecular weight EPDM rubber containing oil as a raw material rubber, and high-charge blending of carbon black in the vulcanization compounding, oil resistance, pressure resistance, vibration resistance required for workability and air inlet hose during molding A satisfactory EPDM rubber composition is disclosed.

EPDM rubber containing oil, which is a raw material rubber, has a molecular weight (Mw) of 1,000,000 to 1,500,000 and preferably contains 70 to 80 parts by weight of oil with respect to 100 parts by weight of EPDM rubber. Oil is added during the synthesis of EPDM rubber, and the oils used include paraffinic white oils, paraffinic process oils, naphthenic process oils, and aromatic process oils. It is preferable to use paraffin type white oil which is excellent in workability and little discoloration by environmental change. When the molecular weight of the EPDM rubber is less than 1,000,000, the carbon black, which is an inorganic filler, may not be filled to a high content, and thus the oil resistance of the composition may be degraded. If the molecular weight is too high, the mixing workability may be reduced. In addition, if the content of the oil is out of the above range there may be a problem that the dispersibility of the material during the mixing operation is inferior. In the case of a high molecular weight EPDM rubber having a molecular weight of usually 400,000 or more, the mixing workability is not good, but it is possible to ensure good mixing workability by containing the oil itself within the above range. Commercialized products satisfying these properties include KEP-980 of Kumho Polychem Co., Ltd.

The carbon black is used as an inorganic filler to improve oil resistance, and may use one or more selected from fast extruding furnace (FEF), medium thermal (MT), and high abrasion furnace (HAF). Preferably, FEF with less shrinkage deformation during extrusion, low heat generation and stable surface, MT with high particle size, thermal stability and processability, and HAF with excellent physical balance and excellent workability and high wear resistance are used. Good to do. The content is preferably used in an amount of 200 to 250 parts by weight based on 175 parts by weight of the raw material rubber. When the content is less than 200 parts by weight, the content of the raw material rubber in the composition may increase, resulting in a drop in oil resistance. It is difficult to mold the product because of the problem of sex. In the case of mixing and using the three kinds of carbon black, FEF 100 ~ 130 parts by weight, MT 40 ~ 50 parts by weight, and HAF 60 ~ 70 parts by weight based on the product performance, workability, and physical properties with respect to 175 parts by weight of raw rubber It is preferable to use. In the present invention, unlike the conventional EPDM rubber composition, it is possible to satisfy the durability, that is, oil resistance required by the air inlet hose material by filling the carbon black as described above.

The sulfur is used as a crosslinking agent, and the precursor is preferably at least one selected from powdered sulfur, insoluble sulfur, and precipitated sulfur. In the present invention, using 0.3 to 0.8 parts by weight based on 175 parts by weight of the raw material rubber, if the amount is too small, there is not enough cross-linking may be a problem in durability, if exceeding 0.8 parts by weight may cause scorch in the molded product.

The vulcanization accelerator acts as an activator of other vulcanization accelerators, replaces a part of sulfur, and is excellent in aging resistance and heat resistance. Zinc di-n-butyldithiocarbamate, stabilize the properties of vulcanized rubber, non-contaminating tetramethyl-thiuram disulfide, and acidic accelerator 2-mercaptobenzothiazole, which exhibits flat vulcanizability and has excellent aging resistance and physical properties, is mixed and used. The amount used is 0.5-1 part by weight of dipentamethylenethiuram tetrasulfide, 0.5-1 part by weight of zinc di-n-butyldithiocarbamate, 0.5-1 part by weight of tetramethyl-thiuram disulfide, based on 175 parts by weight of raw material rubber, And it is preferable that it is 1.5-2.5 weight part of 2-mercaptobenzothiazoles. If the amount of vulcanization accelerator is used too little, the promotion efficiency is low, and the physical properties of the product itself may be affected by incomplete vulcanization when forming the product.On the contrary, when the amount is too high, there may be a problem of heat resistance and scorch of the product due to excessive crosslinking reaction. In particular, excessive use of dipentamethylenethiuram tetrasulfide may cause discoloration of the molded article.

As the plasticizer, a mixture of paraffin oil and ester oil is used, and the amount of the plasticizer is preferably 50 to 60 parts by weight based on 175 parts by weight of the raw rubber. If the content of the plasticizer is too small, there is a problem in workability, which causes problems in flowability during extrusion molding. Too much can cause bleaching in molded articles.

As the anti-aging agent, α-dimethylbenzyl-diphenylamine having excellent antioxidant effect, 2-mercaptobenzoimidazole without discoloration and contamination, and degradation of heat A mixed trimethyl dihydroquinoline polymer (Polymerized trimethyl dihydroquinoline) is used. Specifically, it is preferable to use 1 to 2.5 parts by weight of each of the three anti-aging agents based on 175 parts by weight of the raw material rubber. If the amount is too small, there may be a problem in heat aging resistance, and when used too much, It is better to select the above range since discoloration may occur.

In addition to the essential components, a processing aid commonly used to increase crosslinking efficiency may be further added as necessary. Specific examples thereof may include stearic acid, zinc oxide, and magnesium oxide. In the case of using a processing aid, it is preferable to use 12 parts by weight or less with respect to 175 parts by weight of raw rubber, but when used in excess, problems may occur in heat resistance due to overcrosslinking. In addition, graphite, molybdenum disulfide, wax, or the like may be further added as other additives.

The product to which the EPDM rubber composition of the present invention is applied can be manufactured by the following method. EPDM rubber containing oil is introduced into the mixer and then kneaded by adding carbon black to the composition ratio. Thereafter, sulfur, a vulcanization accelerator, a plasticizer and an anti-aging agent may be added to the composition ratio, and may be manufactured by injection molding at a vulcanization condition of a vulcanization temperature of 160 to 180 ° C. and a vulcanization time of 2 to 3 minutes.

The EDPM rubber composition of the present invention is capable of high filling of carbon black by using EPDM rubber containing oil as a raw material rubber, and thus has excellent oil resistance, internal pressure resistance, and vibration resistance. Therefore, it can be usefully applied to automobile air intake hoses, etc., which were difficult to apply to conventional EPDM rubber materials.

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 and 2 and Comparative example  1-4

doing The rubber composition of the formulation as shown in Table 1 was injection molded to prepare an air inlet hose. Comparative Examples 1-4 are mix | blending of the composition for cooling system hoses using general general purpose EPDM rubber.

division Parts by weight Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 EPDM
Rubber KEP-980 175 175 - 175 - - KEP-570F - - 100 - - - Royalene 645 - - - - 175 175 weapon
Filler FEF 100 130 170 180 80 40 MT 40 40 - 55 55 80 HAF 70 70 - - 70 40 Calcium carbonate - - 55 - - - sulfur 0.5 0.3 0.8 0.7 0.3 0.3 cure
accelerant TRA One One 0.3 - 1.6 One BZ 0.8 0.8 One 2.5 0.8 0.5 TT One 0.7 2.4 0.8 0.5 1.5 M 2.5 2 - - 2 2 Plasticizer Paraffin oil 50 50 70 40 45 45 Ester oil 50 50 - - 40 70 Aging
Inhibitor CD 2 2 - - 2 2 MB 2 2 - One 2 2 RD 1.5 1.5 - One 1.5 1.5 Processing
pharmacy Stearic acid One One One 2 One One Zinc oxide - 10 7 10 - - Vulcanization Condition 160 ℃, 3 minutes 160 ℃, 3 minutes 150 ℃, 20 minutes 160 ℃, 12 minutes 160 ℃, 5 minutes 160 ℃, 5 minutes KEP-980: 75 parts by weight of paraffinic white oil based on 100 parts by weight of EPDM rubber, molecular weight 1,000,000 [Kumho Polychem Co., Ltd.]
KEP-570C: No oil, molecular weight 400,000 [Kumho Polychem Co., Ltd.]
Royalene 645: 75 parts by weight of paraffin-based process oil, based on 100 parts by weight of EPDM rubber, molecular weight 500,000 [UNIROYAL]
FEF: Carbon Black [N550, Corax Co., Ltd.]
MT: Carbon Black [N990, Corax Co., Ltd.]
HAF: Carbon Black [N330, Corax Co., Ltd.]
Hwang: [Miwon Corporation]
TRA: dipentamethylenethiuram tetrasulfide [NOC company]
BZ: zinc di-n-butyldithiocarbamate [Rhein-hemie company]
TT: Tetramethyl-thiuram disulfide [Rhein-hemie company]
M: 2-mercaptobenzothiazole [Ohuchi Shinko Kagaku Co., Ltd.]
Paraffin oil, ester oil [Michang Petroleum Co., Ltd.]
CD: α-dimethylbenzyl-diphenylamine [Ohuchi Shinko Chemical Co., Ltd.]
MB: 2-mercaptobenzoimidazole [RTVANDERBILT]
RD: trimethyl dihydroquinoline polymer

Material property evaluation

The property evaluation method was carried out to evaluate the properties of the air inlet hose material according to the MS263-79, the Hyundai Air Intake Hose Material Specification. The specific test method was carried out by pressing and vulcanizing a thin sheet (150 x 150 mm, 2 to 4 mm thick) made under the same mixing conditions as the air inlet hose mixture, and then punching it with a rubber test piece specified by our company. Physical properties were measured according to ASTM D395 (compressed permanent shrinkage), ASTM D412 (tensile), ASTM D573 (air heat aging), and ASTM D471 (fluid aging). The results are shown in Table 2 below.

Evaluation item (HMC standard) Standard value Example Comparative example One 2 One 2 3 4 condition
Properties Hardness (Hs) 75 ± 5 70 70 71 75 72 73 Tensile Strength (Mpa) 8 MIN 11 12 10 9.3 12 9.3 % Elongation 200 MIN 255 260 215 257 256 303 100% Modulus (Mpa) 4 MIN 5.2 5.4 3 4.3 3.6 3.8 Tear strength (Kn / m) 15 MIN 30 32 21 27 40 27 Heat resistance
(110 ℃, 1000 hr) Hardness change (Hs) +14 MAX +5 +5 +13 +11 +6 +7 Tensile Strength Change (%) -20 MAX -3 -2 -23 +24 +11 -17 Elongation rate of change (%) -69 MAX -36 -31.7 -34 +53 -21 -40 Heat resistance
(130 ° C, 168 hr) Hardness change (Hs) +14 MAX +7 +7 +13 +13 +8 +8 Tensile Strength Change (%) ± 20 MAX -5 -0.2 -19 +30.8 -3.8 -11 Elongation rate of change (%) -60 MAX -26 -23.4 -54 -66.7 -37.8 -33.4 Fuel resistance
(Fuel C, 23 ° C.,
70 hr) Hardness change (Hs) -35 MAX -23 -22 -37 -27 -23 -24 Tensile Strength Change (%) -50 MAX -44 -42.3 -48 -52.5 -37 -45 Elongation rate of change (%) -60 MAX -35.2 -36.5 -50 -51.5 -51 -35 Volume change rate (%) +65 MAX +56.6 +57.3 +145 +46.9 +67 +59 Oil resistance
(No. 3, 130 ° C,
168 hr) Hardness change (Hs) -50 MAX -30 -29 -47 -38 -27 -38 Tensile Strength Change (%) -50 MAX -35.1 -37.1 -57 -57.8 -59.6 -57 Elongation rate of change (%) -60 MAX -11.5 -9.4 -29 -28.1 -38.9 -41.7 Volume change rate (%) +75 MAX +63 +61 +150 +73.5 +63.9 +68.6 Alcohol resistant
(Fuel B +
15% methanol,
23 ° C., 70 hr) Hardness change (Hs) -40 MAX -19 -20 -43 -24 -35 -34 Tensile Strength Change (%) -40 MAX -30.5 -32.2 -56 -35.9 -18 -21 Elongation rate of change (%) -45 MAX -28.1 -26.3 -50 -40.1 -45 -39.3 Volume change rate (%) +70 MAX +44.4 +45.3 +163 +30.7 +69 +64 Compressed permanently reduced rate (120 ℃, 70 hr) 60 MAX 30 32 45 55 33 54

Hose Performance Evaluation

In order to evaluate the performance of the air inlet hoses manufactured in Examples 1 to 2 and Comparative Examples 2 to 4, the internal pressure and the negative pressure tightness were tested under the following test conditions according to the ES28138-03, which is the performance standard of the Hyundai air intake hose. The test results are shown in Table 3 below.

1) Initial aging test

Each of the prepared hoses was aged at 140 ° C. for 1 hour and then tested at 100 ° C. in a hose under a pressure of -80 mmHg.

2) Heat aging test

Each of the prepared hoses were aged at 140 ° C. for 70 hours, then left at room temperature for 3 hours, then aged at 140 ° C. for 1 hour, and then tested at 100 ° C. under a pressure of -80 mmHg.

3) Cold and cold vibration fatigue test

The manufactured hose was subjected to five cycles of the atmosphere temperature at -40 ° C to 120 ° C over 60 hours while oscillating at an amplitude of ± 25 mm and a frequency of 5 Hz, followed by aging at 140 ° C for 1 hour, and then in the hose at 100 ° C. Tested at pressure -80 mmHg conditions.

4) Low temperature vibration fatigue test

Each of the prepared hoses were aged at 140 ° C. for 70 hours, and then subjected to vibration fatigue at -25 ° C. for 6 hours at an amplitude of ± 15 mm and a frequency of 5 Hz. Tested under conditions.

Hose condition Test Items Test result Example 1 Example 2 Comparative Example 2 Comparative Example 3 Comparative Example 4 Early aging Internal pressure 5.1% 4.9% 13.5% 2.4% 4.0% 97.2% 96.3% 99.3% 99.5% 99.0% Negative pressure No leak No leak 2.38 mL / min No leak No leak Heat Aging Internal pressure 3.3% 1.3% 12.6% 2.1% 2.7% 97.2% 97.5% 99.6% 99.5% 99.1% Negative pressure No leak No leak 2.54 mL / min No leak No leak Exterior No crack No crack No crack No crack No crack Heat Aging
after
Cold-resistant vibration fatigue Internal pressure 5.1% 4.5% 3.5% 2.0% 1.6% 95.0% 95.1% 85% 99.6% 99.3% Negative pressure No leak No leak 2.55 mL / min No leak No leak Exterior No crack No crack Crack Crack Crack Low temperature vibration fatigue Internal pressure 4.5% 4.2% 13.1% 2.3% 2.9% 95.2% 94.5% 99.4% 99.5% 99.0% Negative pressure No leak No leak 2.19 mL / min No leak No leak Exterior No crack No crack No crack No crack No crack ※ Required component
Internal pressure: Outer diameter change 10% or less, Outer diameter restoration rate 90% or more
Negative pressure tightness: 10 mL / min or less

As shown in the results of Tables 2 and 3, in the case of Comparative Example 1 using the KEP-570F, a general-purpose EPDM rubber, it can be seen that the fuel oil resistance, oil resistance, and alcohol oil physical properties are greatly decreased even though the carbon black is highly charged. . This is because EPDM rubber has low resistance to fuel oil. In addition, in Comparative Example 2, in which dipentamethylenethiuram tetrasulfide and 2-mercaptobenzothiazole were not used as a vulcanization accelerator, there was a problem in heat resistance due to incomplete vulcanization and poor oil resistance. In Comparative Example 3 and Comparative Example 4 using Royalene 645 as the raw material rubber, even though the raw material rubber contained oil, oil resistance was not good due to the difference in the molecular weight of the raw material rubber, and Comparative Example 4 was low in carbon black. Results In comparison with Comparative Example 3, physical properties were lower in terms of internal pressure resistance and vibration resistance. In Examples 1 and 2, by optimizing the content of the specific raw material rubber, carbon black, vulcanization accelerator and plasticizer, the results satisfy the oil resistance, pressure resistance, vibration resistance, and heat resistance required for the air inlet hose material.

As a result, the EPDM rubber composition in which the EPDM rubber containing oil is selected as the raw material rubber and the carbon black is high-filled, and a specific vulcanization accelerator and the like are added and crosslinked at an optimum ratio together with sulfur are conventional EPDM. Unlike the rubber composition, oil resistance, pressure resistance, and vibration resistance were excellent, and thus, it could be confirmed that it is applicable to a material of a car air intake hose.

Claims (3)

Per 175 parts by weight of oil-containing EPDM rubber
200 to 250 parts by weight of carbon black;
Sulfur 0.3 to 0.8 parts by weight;
0.5-1 weight part of dipentamethylenethiuram tetrasulfide, a vulcanization accelerator, 0.5-1 weight part of zinc di-n-butyldithiocarbamate, 0.5-1 weight part of tetramethyl-thiuram disulfide and 2-mercaptobenzothia Sol 1.5 to 2.5 parts by weight;
50 to 60 parts by weight of a plasticizer paraffin oil and 50 to 60 parts by weight of ester oil; And
1 to 2.5 parts by weight of an anti-aging agent α-dimethylbenzyl-diphenylamine, 1 to 2.5 parts by weight of 2-mercaptobenzoimidazole and 1 to 2.5 parts by weight of trimethyl dihydroquinoline polymer;
EPDM rubber composition comprising a.
According to claim 1, wherein the carbon black is based on 175 parts by weight of oil-containing EPDM rubber FEF (Fast Extruding Furnace) 100 ~ 130, MT (40 ~ 50 parts by weight) and HAA (High Abrasion Furnace) 60 ~ EPDM rubber composition, characterized in that the mixture of 70 parts by weight.
The EPDM rubber composition according to claim 1, further comprising 7 to 12 parts by weight of a processing aid based on 175 parts by weight of the oil-containing EPDM rubber.