KR20240057956A - ethylene-propylene Diene Rubber Composition with excellent Processing stability and Mechanical properties - Google Patents

Abstract

The present disclosure relates to an ethylene-propylene-diene rubber (EPDM) composition. As it contains a specific vulcanization accelerator composition, the vulcanization speed is fast and thus the processing efficiency is high. It has a high cross-linking density and has excellent mechanical properties, while at the same time processing stability, which is a trade-off. There is an advantage that it can also be improved.

Description

{ethylene-propylene Diene Rubber Composition with excellent processing stability and mechanical properties}

The present disclosure relates to an ethylene-propylene-diene rubber composition having excellent processing stability and mechanical properties.

Ethylene-propylene-diene rubber is the third most consumed product in the world after styrene butadiene rubber and butadiene rubber. It has excellent weather resistance, ozone resistance, and electrical insulation, and exhibits physical properties such as low compression strain, high strength, and high elongation. For this reason, it is widely used in the automobile industry, construction industry, electronics and electrical industries.

Various additives are added to rubber during processing, and the mechanical, chemical, thermal properties or processing characteristics of rubber may vary depending on the type and content of the additives. Common additives include organic/inorganic fillers, vulcanization agents, vulcanization accelerators, and plasticizers. In particular, the vulcanization accelerator not only improves work efficiency by promoting the vulcanization reaction of rubber, but also affects the crosslink density of rubber, thereby improving mechanical properties. However, when a vulcanization accelerator is used to improve processing efficiency and crosslinking density, the vulcanization reaction may occur too quickly, which may result in a decrease in the processing stability of the composition.

Therefore, there is an urgent need for research and development on rubber compositions that have high processing efficiency and excellent physical properties due to the short curing time of rubber products, while also providing excellent processing stability.

The purpose of the present disclosure is to provide a rubber composition that has a fast vulcanization rate, high crosslinking density, and excellent mechanical properties while exhibiting excellent processing stability.

The present disclosure provides a rubber composition comprising ethylene-propylene-diene rubber (EPDM), an inorganic filler, sulfur, and a vulcanization accelerator composition, wherein the vulcanization accelerator composition includes 4,4'-dithiodimorpholine (DTDM), zinc It is characterized by being composed of ethyldithiocarbamate (ZDEC), 1,3-diphenylguanidine (DPG), tetramethyl thiuram disulfide (TMTD), and 2-mercaptobenzothiazole (MBT).

According to one embodiment, the vulcanization accelerator composition may be included in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the ethylene-propylene-diene rubber.

According to one embodiment, the sulfur may be included in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the ethylene-propylene-diene rubber.

According to one embodiment, 4,4'-dithiodimorpholine may be included in an amount of 50 to 150 parts by weight based on 100 parts by weight of sulfur.

According to one embodiment, the zinc diethyldithiocarbamate may be included in an amount of 50 to 200 parts by weight based on 100 parts by weight of sulfur.

According to one embodiment, the total weight of the 4,4'-dithiodimorpholine and zinc diethyldithiocarbamate may be 100 to 300 parts by weight based on 100 parts by weight of sulfur.

According to one embodiment, the weight ratio of 4,4'-dithiodimorpholine to zinc diethyldithiocarbamate may satisfy 0.5 to 1.5:1.

According to one embodiment, the rubber composition may satisfy the following conditions (1) to (3).

(1) Δt30 > 3min.

(2) Degree of vulcanization > 10.5 lb-in

(3) tc90 <2 min.

(In conditions (1) to (3) above,

Δt30 is the Delta Mooney scorch time measured at a temperature of 180°C for the rubber composition before vulcanization, and the degree of vulcanization (Cure State) is based on ASTM D 2084 at a temperature of 180°C. It is the difference between the torque at the highest point and the torque at the lowest point measured, and tc90 is the vulcanization time, which is the time during which the entire vulcanization reaction progresses to 90%.)

According to one embodiment, the 1,3-diphenylguanidine may be included in an amount of 30 to 150 parts by weight based on 100 parts by weight of sulfur.

According to one embodiment, the tetramethyl thiuram disulfide may be included in an amount of 30 to 150 parts by weight based on 100 parts by weight of sulfur.

According to one embodiment, the 2-mercaptobenzothiazole may be included in an amount of 10 to 80 parts by weight based on 100 parts by weight of sulfur.

According to one embodiment, the inorganic filler may be included in an amount of 5 to 120 parts by weight based on 100 parts by weight of the ethylene-propylene-diene rubber.

According to one embodiment, the rubber composition includes zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, stearic acid, zinc stearate, palmitic acid, It may further include one or a combination of two or more selected from the group consisting of linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, and derivatives thereof.

The present disclosure can provide a rubber molded article manufactured from the above-described rubber composition.

The present disclosure is an ethylene-propylene-diene rubber (EPDM) composition containing a vulcanization accelerator composition, which exhibits the effect of improving processing stability while having a fast vulcanization speed, high crosslinking density, and excellent mechanical properties by including the vulcanization accelerator composition. You can. Specifically, the rubber composition can simultaneously realize excellent processing stability and mechanical properties by exhibiting Mooney scorch time difference, degree of vulcanization, tensile strength, and vulcanization time within a specific range.

The advantages and features of the present invention and methods for achieving them will become clear with reference to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. “And/or” includes each and every combination of one or more of the mentioned items.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings that can be commonly understood by those skilled in the art in the technical field to which the present invention pertains. When it is said that a part "includes" a certain element throughout the specification, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary. The singular also includes the plural, unless specifically stated in the phrase.

As a result of continuous research by the present applicant to produce a rubber composition that is excellent in both vulcanization speed and processing stability, which are conventional trade-offs, in the case of an ethylene-propylene-diene rubber composition containing a vulcanization accelerator composition according to an embodiment, the vulcanization speed is The present invention was completed by discovering that the processing efficiency is fast, the crosslinking density is high, so the mechanical properties are excellent, and the processing stability is also excellent.

The present disclosure provides a rubber composition comprising ethylene-propylene-diene rubber (EPDM), an inorganic filler, sulfur, and a vulcanization accelerator composition, wherein the vulcanization accelerator composition includes 4,4'-dithiodimorpholine (DTDM), zinc It is characterized by being composed of ethyldithiocarbamate (ZDEC), 1,3-diphenylguanidine (DPG), tetramethyl thiuram disulfide (TMTD), and 2-mercaptobenzothiazole (MBT).

According to one embodiment, the vulcanization accelerator composition may be included in an amount of 0.5 to 20 parts by weight, specifically 1 to 15 parts by weight, and more specifically 3 to 8 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene rubber.

According to one embodiment, the sulfur may be included in an amount of 0.05 to 5 parts by weight, specifically 0.1 to 5 parts by weight, and more specifically 1 to 3 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene rubber.

According to one embodiment, the 4,4'-dithiodimorpholine may be included in an amount of 10 to 300 parts by weight, specifically 50 to 150 parts by weight, and more specifically 60 to 100 parts by weight, based on 100 parts by weight of sulfur.

According to one embodiment, the zinc diethyldithiocarbamate may be included in an amount of 10 to 400 parts by weight, specifically 50 to 200 parts by weight, and more specifically 60 to 100 parts by weight, based on 100 parts by weight of sulfur.

According to one embodiment, the total weight of the 4,4'-dithiodimorpholine and zinc diethyldithiocarbamate is 50 to 500 parts by weight, specifically 100 to 300 parts by weight, based on 100 parts by weight of sulfur. Specifically, it may be included in 150 to 250 parts by weight.

According to one embodiment, the weight ratio of 4,4'-dithiodimorpholine to zinc diethyldithiocarbamate is 0.1 to 5:1, specifically 0.5 to 1.5:1, more specifically 0.5 to 1.2:1. can be satisfied.

When the 4,4'-dithiodimorpholine and zinc diethyldithiocarbamate satisfy the above-mentioned content or/and weight ratio, the degree of vulcanization is high, the tensile strength is excellent, the vulcanization speed is fast, and processing stability is high. An excellent rubber composition can be provided.

According to one embodiment, the 1,3-diphenylguanidine may be included in an amount of 10 to 200 parts by weight, specifically 30 to 150 parts by weight, and more specifically 50 to 100 parts by weight, based on 100 parts by weight of sulfur.

According to one embodiment, the tetramethyl thiuram disulfide may be included in an amount of 10 to 200 parts by weight, specifically 30 to 150 parts by weight, and more specifically 50 to 100 parts by weight, based on 100 parts by weight of sulfur.

According to one embodiment, the 2-mercaptobenzothiazole may be included in an amount of 5 to 150 parts by weight, specifically 10 to 80 parts by weight, and more specifically 30 to 50 parts by weight, based on 100 parts by weight of sulfur.

According to one embodiment, the ethylene-propylene-diene rubber (EPDM) may be a commercially available EPDM rubber raw material. In addition, it may further include, but is not limited to, natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, and mixtures thereof.

According to one embodiment, the inorganic filler may be an inorganic filler commonly used in rubber production or a commercially available product without limitation. Specifically, the inorganic filler may be carbon black. The carbon black includes furnace carbon black such as SAF (N110), ISAF (220), HAF (N330), MAF, FEF (N550), SRF, GPF (N660), APF, FF, CF, SCF and ECF; Acetylene carbon black; Thermal carbon blacks such as FT and MT (M990); Channel carbon black such as EPC, MPC and CC; and graphite; etc. may be used, and the carbon black may have an average particle diameter of 5 to 500 nm, specifically 20 to 350 nm, and more specifically 30 to 80 nm, but is not limited thereto.

According to one embodiment, the inorganic filler may be included in an amount of 1 to 200 parts by weight, specifically 5 to 120 parts by weight, and more specifically 50 to 100 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene rubber.

According to one embodiment, the rubber composition includes zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, stearic acid, zinc stearate, palmitic acid, It may further include one or a combination of two or more selected from the group consisting of linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, and derivatives thereof. Specifically, the zinc oxide and the stearic acid can be used together, and in this case, the zinc oxide is dissolved in the stearic acid to form an effective complex with the vulcanization accelerator according to one embodiment, producing sulfur that is advantageous for the vulcanization reaction. It has the advantage of facilitating the vulcanization reaction of rubber. At this time, the total weight of the zinc oxide and stearic acid may be 0.1 to 10 parts by weight, specifically 2 to 8 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene rubber. Additionally, the weight ratio of zinc oxide to stearic acid may be 1 to 10:1, specifically 2 to 8:1, but is not limited thereto.

According to one embodiment, the rubber composition may further include one or more additives selected from anti-aging agents and softeners.

The softener may be added to improve the plasticity and processability of the rubber composition or to lower the hardness of the vulcanized rubber, and is, for example, selected from the group consisting of paraffinic oil, aromatic oil, naphthenic oil, and combinations thereof. Any one may be appropriately selected and used, but is not limited thereto.

The anti-aging agent can be added to suppress the chain reaction in which rubber is naturally oxidized by oxygen. For example, the anti-aging agent may be amine-based, phenol-based, quinoline-based, imidazole-based, carbamic acid metal salt, wax, and combinations thereof. Any one selected from the group may be appropriately selected and used, but is not limited thereto.

According to one embodiment, the rubber composition may further include a vulcanization accelerator other than the vulcanization accelerator composition described above, as long as it does not impair the desired physical properties such as tensile strength, degree of vulcanization, and processing stability (Δt30). However, when zinc N,N-dibutyldithiocarbamate (ZDBC) is included, the processing stability of the rubber composition cannot be secured, so the rubber composition is zinc N,N-dibutyldithiocarbamate (ZDBC). ZDBC) may not be substantially included.

According to one embodiment, the rubber composition has a Delta Mooney scorch time (Δt30) greater than 2 minutes (min.), specifically 2.5 minutes to 5 minutes (min.), more specifically 3 minutes ( min.) may be exceeded. The specific measurement method is the same as described later, and when the Mooney scorch time is in the above-mentioned range, rapid vulcanization reaction is suppressed during processing, thereby ensuring excellent processing stability.

According to one embodiment, the rubber composition may have a cure state measured according to ASTM D 2084 greater than 10.0 lb-in, specifically 10.3 to 15 lb-in, and more specifically greater than 10.5 lb-in. there is. The specific measurement method is the same as described later, and when the degree of vulcanization is in the range described above, mechanical properties such as tensile strength, modulus, and hardness can be improved.

According to one embodiment, the rubber composition may have a vulcanization time (tc90), which is the time at which 90% of the entire vulcanization reaction progresses, of less than 3 minutes, specifically less than 2 minutes, and more specifically 1.3 to 1.8 minutes. The specific measurement method is the same as described later, and when the vulcanization time (tc90) is in the above-mentioned range, the vulcanization reaction progresses quickly, increasing the vulcanization speed, and thus the time required for work is shortened, thereby improving vulcanization efficiency. there is.

In addition, in the past, if the vulcanization time was short, processing stability deteriorated, but in the case of a rubber composition containing a vulcanization accelerator composition according to an embodiment, processing stability is complementary to a short vulcanization time, and at the same time, the degree of vulcanization is high and tensile strength is improved. It has the advantage of excellent mechanical properties such as strength.

According to one embodiment, the rubber composition may simultaneously satisfy the following conditions (1) to (3).

(1) Δt30 > 3min.

(2) Degree of vulcanization > 10.5 lb-in

(3) tc90 < 2min.

(In conditions (1) to (3) above,

Δt30 is the Delta Mooney scorch time measured at a temperature of 180°C for the rubber composition before vulcanization, and the degree of vulcanization (Cure State) is based on ASTM D 2084 at a temperature of 180°C. It is the difference between the torque at the highest point and the torque at the lowest point measured, and tc90 is the vulcanization time, which is the time during which the entire vulcanization reaction progresses to 90%.)

When the vulcanization accelerator composition according to one embodiment is included, the vulcanization speed and processing stability, which were conventionally in a conflicting relationship, can be simultaneously improved, and a rubber composition that simultaneously satisfies the conditions (1) to (3) above can be manufactured. there is. In addition, when the 4,4'-dithiodimorpholine and zinc diethyldithiocarbamate satisfy the above-mentioned content or/and weight ratio, the above-described effect can be more significantly realized.

The present disclosure can provide a rubber molded article manufactured from the above-described rubber composition. The rubber composition can be subjected to a vulcanization reaction according to a commonly used or known method. For example, a vulcanization reaction can be performed for a certain period of time at a temperature of 120°C or higher, specifically 150°C or higher, and commonly used or known processing methods such as extrusion and injection can be used. The rubber composition can be vulcanized under certain conditions to form a rubber elastomer with improved mechanical strengths such as tensile strength, 100% modulus, elongation, and hardness.

According to one embodiment, the rubber molded article may have a tensile strength measured according to ASTM D 412 of 180 kgf/cm2 or more, specifically 190 to 300 kgf/cm2, and more specifically 200 kgf/cm2 or more, The specific measurement method is the same as described later.

According to one embodiment, the rubber molded article may have a 100% modulus measured according to ASTM D 412 of 5 kgf/cm2 or more, specifically 15 to 30 kgf/cm2, and more specifically 20 kgf/cm2 or more. , the specific measurement method is the same as described later.

According to one embodiment, the rubber molded product may have an elongation of 550% or more, specifically 560 to 800%, as measured according to ASTM D 412, and the specific measurement method is the same as described later.

According to one embodiment, the rubber molded product may have a hardness of HS 40 or higher, specifically, HS 50 or higher, and the specific measurement method is the same as described later.

The rubber molded product according to one embodiment is manufactured from a rubber composition that has a fast vulcanization speed and a high degree of vulcanization, and at the same time has excellent processing stability, and exhibits mechanical strengths such as excellent tensile strength, 100% modulus, elongation, and hardness, enabling high workability. Efficiency, excellent processing stability, and excellent mechanical properties can be achieved.

Hereinafter, the present invention will be described in detail through examples. However, these are intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to the following examples.

[Physical property evaluation method]

1. Delta Mooney scorch time (Δt30) [min.]

For the rubber composition in the state before vulcanization according to the examples and comparative examples, after preheating for 1 minute at a temperature of 180°C, the viscosity over time was recorded using a Mooney viscometer (Alpha Technologies, MV2000), and the viscosity was measured in Mooney units rather than the lowest viscosity. After measuring the time required to rise by 5 points (t5) and the time required to rise by 35 points (t35), the difference between them was calculated as [Δt30=t35-t5] and recorded as the Mooney Scorch time difference (Δt30). The longer the difference value, the better the processing stability.

2. Cure State [lb-in]

For the rubber compositions in the pre-vulcanization state according to the Examples and Comparative Examples, the change in torque value over time at a temperature of 180°C was measured with a moving die rheometer (Alpha Technologies, MDR2000) in accordance with ASTM D 2084, and the maximum point was The difference between the torque at the maximum torque (MH) and the torque at the lowest point (minimum torque, ML) was calculated as [Cure State=MH-ML] and expressed as the degree of curing. The larger the difference, the higher the degree of curing.

3. Vulcanization time (tc90) [min.]

The time for 90% of the overall vulcanization reaction of the rubber composition according to the Examples and Comparative Examples to proceed was measured at 180°C with a moving die rheometer (Alpha Technologies, MDR2000) in accordance with ASTM D 2084. The shorter the vulcanization time, the higher the vulcanization rate. was evaluated as fast.

4. Mechanical properties

After the rubber composition according to the Examples and Comparative Examples was vulcanized at 180°C for 5 minutes, the tensile strength at break [kgf/cm2], elongation at break [%], and 100% modulus [kgf/cm2] was measured. The measuring device used was a universal testing machine (UTM, Instron 3312), and the specimen was prepared with a dumbbell die C type, and was measured under the conditions of a crosshead speed of 500 mm/min and a 100 kgf load cell.

The hardness (HS) of the rubber compositions according to Examples and Comparative Examples was measured using a spring-type hardness meter (Shore A) after vulcanization under the same conditions.

[Examples and Comparative Examples] Preparation of rubber composition

In a Banbury Mixer at 85°C, 175 parts by weight of EPDM (Suprene 675WF, including EPDM rubber: oil = 100:75), 80 parts by weight of carbon black (N550), 5 parts by weight of zinc oxide (ZnO), and stearic acid ( SA) 1 part by weight was kneaded sequentially at 2-minute intervals and then kneaded for 10 minutes while maintaining 155°C to prepare a rubber compound, which was left at room temperature for 24 hours. Subsequently, sulfur (S-80 (80 wt%)) and a vulcanization accelerator composition were added to the rubber mixture at a temperature of 60°C and kneaded according to Table 1 below to prepare the final rubber composition, according to the physical property evaluation method described above. The physical properties were evaluated and are shown in Table 2.

(part by weight) Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 S-80 1.80 1.80 1.80 1.80 1.80 1.80 DTDM 1.50 1.50 1.50 - 1.50 - DPTT - - - - - 1.50 ZDEC 1.50 2.50 1.50 1.50 - - ZDBC - - 2.50 2.50 2.50 1.50 DPG 1.25 1.25 1.25 1.25 1.25 1.25 TMTD 1.25 1.25 1.25 1.25 1.25 - TMTM - - - - - 1.25 MBT 0.75 0.75 0.75 0.75 0.75 - DM - - - - - 0.75 Total 8.05 8.05 10.55 9.05 9.05 8.05

-DPTT: dipentamethylenethiuram tetrasulphide

-DM: dibenzothiazole disulfide

-TMTM: tetramethylthiuram monosulphide

Properties Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 importance 1.051 1.050 1.054 1.049 1.051 1.052 Δt30[min.] 3.16 3.02 2.33 1.74 2.81 2.03 Curing degree [lb-in] 10.63 10.66 10.61 10.16 10.4 10.31 tc90[min.] 1.57 1.52 1.58 1.2 1.7 1.3 Tensile strength [㎏f/㎠] 200.9 202.3 186 187.6 185.7 139.2 Elongation [%] 575.9 570.4 554.1 588.6 583.9 522 100% modulus [㎏f/㎠] 21.3 20.8 21.5 19.8 20.3 15.8 Hardness [Shore A] 53.6 53.9 52.5 51.1 52.7 55.1

As shown in Tables 1 and 2, Examples 1 and 2 have excellent mechanical properties with a vulcanization degree of 10.5 lb-in or more and a tensile strength of 200 kgf/cm2 or more, and Δt30 was measured for more than 3 minutes, indicating that processing was possible. It was confirmed that stability was excellent.

Comparing Example 1 with Comparative Example 1, it can be seen that elongation and processing stability cannot be secured when ZDBC is added, and when comparing Example 1 with Comparative Example 2, when DTDM is not included, the degree of vulcanization It was found that was insufficient, indicating low tensile strength and hardness, and Δt30 was measured too low, making it impossible to secure processing stability. Additionally, when comparing Example 1 with Comparative Example 3, it was found that when ZDEC was not included, low tensile strength and Δt30 were exhibited, resulting in insufficient mechanical strength and processing stability. In particular, through comparison with Examples and Comparative Examples, as the 4,4'-dithiodimorpholine (DTDM) and zinc diethyldithiocarbamate (ZDEC) were combined, the degree of vulcanization, vulcanization density, and tensile strength It was confirmed that mechanical strength and processing stability can be achieved simultaneously by improving strength and showing a high Δt30.

This allows 4,4'-dithiodimorpholine (DTDM), zinc diethyldithiocarbamate (ZDEC), 1,3-diphenylguanidine (DPG), tetramethyl thiuram disulfide (TMTD) and 2-mer When a rubber composition is manufactured using a vulcanization accelerator composition made of captobenzothiazole (MBT), the vulcanization speed is fast, the processing efficiency is good, and the crosslinking density is high, so it has excellent mechanical properties, but at the same time, there is a trade-off with the vulcanization speed in the past. It was confirmed that processing stability, which is a trade-off, was also improved in a complementary manner.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand the technical idea of the present invention. It will be understood that it can be implemented in other specific forms without changing the essential features. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (14)

A rubber composition comprising ethylene-propylene-diene rubber (EPDM), an inorganic filler, sulfur, and a vulcanization accelerator composition,
The vulcanization accelerator composition includes 4,4'-dithiodimorpholine (DTDM), zinc diethyldithiocarbamate (ZDEC), 1,3-diphenylguanidine (DPG), tetramethyl thiuram disulfide (TMTD), and A rubber composition consisting of 2-mercaptobenzothiazole (MBT). According to paragraph 1,
The vulcanization accelerator composition is a rubber composition comprised in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the ethylene-propylene-diene rubber. According to paragraph 1,
A rubber composition wherein the sulfur is contained in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the ethylene-propylene-diene rubber. According to paragraph 2,
The rubber composition containing 4,4'-dithiodimorpholine in an amount of 50 to 150 parts by weight based on 100 parts by weight of sulfur. According to paragraph 2,
A rubber composition containing 50 to 200 parts by weight of zinc diethyldithiocarbamate based on 100 parts by weight of sulfur. According to clause 5,
A rubber composition in which the total weight of the 4,4'-dithiodimorpholine and zinc diethyldithiocarbamate is 100 to 300 parts by weight based on 100 parts by weight of sulfur. According to clause 5,
A rubber composition wherein the weight ratio of 4,4'-dithiodimorpholine to zinc diethyldithiocarbamate satisfies 0.5 to 1.5:1. In clause 7,
The rubber composition satisfies the following conditions (1) to (3).
(1) Δt30 > 3min.
(2) Degree of vulcanization > 10.5 lb-in
(3) tc90 < 2min.
(In conditions (1) to (3) above,
Δt30 is the Delta Mooney scorch time measured at a temperature of 180°C for the rubber composition before vulcanization, and the degree of vulcanization (Cure State) is measured according to ASTM D 2084 at a temperature of 180°C. It is the difference between the torque at the highest point and the torque at the lowest point measured, and tc90 is the vulcanization time, which is the time during which the entire vulcanization reaction progresses to 90%.) According to paragraph 2,
A rubber composition containing 30 to 150 parts by weight of 1,3-diphenylguanidine based on 100 parts by weight of sulfur. According to paragraph 2,
A rubber composition containing 30 to 150 parts by weight of tetramethyl thiuram disulfide based on 100 parts by weight of sulfur. According to paragraph 1,
A rubber composition containing 10 to 80 parts by weight of 2-mercaptobenzothiazole based on 100 parts by weight of sulfur. According to paragraph 1,
The inorganic filler is a rubber composition comprised in an amount of 5 to 120 parts by weight based on 100 parts by weight of the ethylene-propylene-diene rubber. According to paragraph 1,
The rubber composition includes zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, stearic acid, zinc stearate, palmitic acid, linoleic acid, oleic acid, and lauric acid. A rubber composition further comprising one or a combination of two or more selected from the group consisting of acids, dibutyl ammonium oleate, and derivatives thereof. A rubber molded article manufactured from the rubber composition of any one of claims 1 to 13.